feat(docs): man pages for gasm and every command, guarded against CLI drift

Assisted-by: GLM 5.3 Flash

.gitea/workflows/race.yml

@@ -0,0 +1,37 @@
+# Race, Go. Dispatched by hand, and never a gate on a push or a tag: the release tag is
+# cut only after `just gates` has already raced the tree, so this workflow is the
+# explicit second opinion, not a step of the release.
+#
+# The race detector roughly doubles both time and memory, which the shared runner box
+# cannot afford on every push. Locally it belongs to `just gates`, which runs it once per
+# task; here it is a decision rather than a routine.
+#
+# Every step is one command, so the step that fails is the gate that failed.
+name: Race
+
+on:
+  workflow_dispatch:
+
+env:
+  # One core: parallelism buys no speed here and costs memory the box does not have.
+  GOFLAGS: -p=1
+  GOMAXPROCS: "2"
+
+jobs:
+  race:
+    runs-on: fedora
+    timeout-minutes: 20
+    steps:
+      - uses: actions/checkout@v7
+
+      - uses: actions/setup-go@v6
+        with:
+          go-version-file: go.mod
+          cache: true
+
+      - name: Install gcc
+        # The race detector needs cgo and the runner image carries no C compiler.
+        run: dnf install -y gcc
+
+      - name: Race
+        run: go test -race -count=1 -timeout 10m ./...

.gitea/workflows/release.yml

@@ -1,73 +1,198 @@
-# Release — gasm binaries. Runs on version tags (v0.28.0) pushed to main.
+# Release, Go binaries. Runs on version tags (v1.2.3) pushed to main.
+#
+# The module sits at the repository root: the toolchain records a version only for a root
+# module, measured on go1.27.1, so a build of a module in a subdirectory reports (devel)
+# even at its own <module>/vX.Y.Z tag and this workflow's smoke test can never pass for
+# it. A Go repository is one module at the root.
+#
+# The version contract these steps implement is in the `release` skill, and its point is
+# that nothing is injected: the toolchain records the tag into the binary's build
+# information, so the build simply has to happen at the tag, which the trigger guarantees.
+#
+# The gates run in their own job, once, before the matrix, minus the race detector: race
+# never runs on a push path or a tag, and the local gate raced this tree before the tag
+# was cut. Putting the gates inside the matrix would run the whole suite once per target
+# on the box that also hosts the forge. Each job validates the tag for itself rather than
+# passing a value between jobs, so no workflow feature has to be trusted for the version
+# to reach the file name.
 name: Release
 
 on:
   push:
     tags: ["v*"]
 
+env:
+  # The box is shared with the forge, so parallelism is bounded on purpose. The gates job
+  # needs it most; the build jobs inherit it for their parallel compilation.
+  GOFLAGS: -p=1
+  GOMAXPROCS: "2"
+
 jobs:
+  gates:
+    runs-on: fedora
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@v7
+
+      - uses: actions/setup-go@v6
+        with:
+          go-version-file: go.mod
+          cache: true
+
+      - name: Install Perl
+        # Perl for the steps below. The install is a no-op where the package
+        # is already present.
+        run: dnf install -y perl
+
+      - name: Validate the tag
+        env:
+          VERSION: ${{ gitea.ref_name }}
+        run: |
+          perl -e '
+            my $v = $ENV{VERSION} // q{};
+            $v =~ m{^v[0-9]+(\.[0-9]+){0,2}([-+].*)?$}
+              or die qq{ERROR: expected a semver tag like v1.2.3, got: $v\n};
+            print qq{tag $v\n};
+          '
+
+      - name: Build
+        run: go build ./...
+
+      - name: Format
+        run: |
+          perl -e '
+            open(my $g, q{-|}, q{gofmt}, q{-l}, q{.}) or die qq{gofmt: $!};
+            my @bad = <$g>;
+            close($g);
+            print @bad;
+            exit(@bad ? 1 : 0);
+          '
+
+      - name: Vet
+        run: go vet ./...
+
+      - name: Modernise
+        run: go fix -diff ./...
+
+      - name: Tests
+        # The same command as in test.yml, so the floor is the same number everywhere.
+        run: go test -count=1 -timeout 10m -coverprofile=coverage.out ./arch/... ./asm/... ./ast/... ./disasm/... ./format/... ./lexer/... ./lint/... ./lsp/... ./parser/... ./token/... ./verify/...
+
+      - name: Coverage floor
+        run: |
+          perl -e '
+            open(my $c, q{-|}, q{go}, q{tool}, q{cover}, q{-func=coverage.out}) or die qq{cover: $!};
+            my $total;
+            while (my $l = <$c>) { $total = $1 if $l =~ m{^total:\s+\S+\s+([0-9.]+)%} }
+            close($c);
+            die qq{no total line in coverage.out\n} unless defined $total;
+            printf qq{Total coverage: %s%%\n}, $total;
+            exit($total < 80 ? 1 : 0);
+          '
+
   build:
     runs-on: fedora
+    timeout-minutes: 25
+    needs: gates
     strategy:
       fail-fast: false
       matrix:
+        # Portable targets: amd64, arm64, loong64 and riscv64 on Linux, at the toolchain
+        # default level. No 32-bit, no wasm, no macOS, no Windows. FreeBSD stays out until
+        # verify/jit.go ports off syscall.Mprotect: the Go syscall package defines no
+        # Mprotect for freebsd, and verify/jit.go:50 calls it to drop the write bit from
+        # the JIT mapping, so every freebsd target fails to build with "undefined:
+        # syscall.Mprotect" (verified for amd64, arm64 and riscv64 on go1.27.1).
         include:
           - goos: linux
             goarch: amd64
           - goos: linux
             goarch: arm64
-          - goos: linux
-            goarch: riscv64
           - goos: linux
             goarch: loong64
+          - goos: linux
+            goarch: riscv64
     steps:
       - uses: actions/checkout@v7
 
       - uses: actions/setup-go@v6
         with:
-          go-version: "1.27"
+          go-version-file: go.mod
+          cache: true
 
-      - name: Download dependencies
+      - name: Install Perl
-        run: go mod download
+        run: dnf install -y perl
 
-      - name: Validate tag and build
+      - name: Validate the tag
-        id: build
+        id: version
         env:
           VERSION: ${{ gitea.ref_name }}
         run: |
-          set -euo pipefail
+          perl -e '
+            my $v = $ENV{VERSION} // q{};
+            $v =~ m{^v[0-9]+(\.[0-9]+){0,2}([-+].*)?$}
+              or die qq{ERROR: expected a semver tag like v1.2.3, got: $v\n};
+            (my $nv = $v) =~ s{^v}{};
+            open(my $o, q{>>}, $ENV{GITEA_OUTPUT}) or die qq{GITEA_OUTPUT: $!};
+            print $o qq{version_no_v=$nv\n};
+            close($o);
+            print qq{version $nv\n};
+          '
 
-          if ! echo "$VERSION" | grep -qE '^v[0-9]+(\.[0-9]+){0,2}([-+].*)?$'; then
+      - name: Build
-            echo "ERROR: expected a semver tag like v1.2.3, got: '$VERSION'"
+        env:
-            exit 1
+          VERSION_NO_V: ${{ steps.version.outputs.version_no_v }}
-          fi
+          GOOS: ${{ matrix.goos }}
-
+          GOARCH: ${{ matrix.goarch }}
-          VERSION_NO_V="${VERSION#v}"
+          CGO_ENABLED: "0"
-          echo "version_no_v=${VERSION_NO_V}" >> "$GITEA_OUTPUT"
+        run: |
-
+          # Nothing is injected. The toolchain records the tag into the binary's build
-          mkdir -p bin
+          # information, so the version is right because this build happens at the tag, and
-          GOOS=${{ matrix.goos }} GOARCH=${{ matrix.goarch }} CGO_ENABLED=0 \
+          # there is no path for anyone to get wrong. -s -w only strips symbols.
-            go build -ldflags "-s -w -X main.version=${VERSION_NO_V}" \
+          go build -ldflags "-s -w" -o "bin/gasm-${VERSION_NO_V}-${GOOS}-${GOARCH}" ./cmd/gasm
-              -o "bin/gasm-${VERSION_NO_V}-${{ matrix.goos }}-${{ matrix.goarch }}" \
-              ./cmd/gasm
 
+      # Artifacts stay on v3: v4 and later detect Gitea as GHES and abort.
       - name: Upload artifact
         uses: actions/upload-artifact@v3
         with:
           name: gasm-${{ matrix.goos }}-${{ matrix.goarch }}
-          path: bin/gasm-${{ steps.build.outputs.version_no_v }}-${{ matrix.goos }}-${{ matrix.goarch }}
+          path: bin/gasm-${{ steps.version.outputs.version_no_v }}-${{ matrix.goos }}-${{ matrix.goarch }}
           if-no-files-found: error
 
       - name: Smoke test
+        # Only a binary matching the runner can be run here. The check is not that --version
+        # exits cleanly but that it reports the tag and nothing more: a build outside version
+        # control reports (devel), and a build whose tree was dirty reports +dirty, and both
+        # would otherwise be published.
         if: matrix.goos == 'linux' && matrix.goarch == 'amd64'
+        env:
+          TAG: ${{ gitea.ref_name }}
+          BIN: bin/gasm-${{ steps.version.outputs.version_no_v }}-${{ matrix.goos }}-${{ matrix.goarch }}
         run: |
-          chmod +x bin/gasm-${{ steps.build.outputs.version_no_v }}-${{ matrix.goos }}-${{ matrix.goarch }}
+          perl -e '
-          ./bin/gasm-${{ steps.build.outputs.version_no_v }}-${{ matrix.goos }}-${{ matrix.goarch }} --version
+            my $want = $ENV{TAG} // die qq{ERROR: no tag\n};
+            open(my $bin, q{-|}, $ENV{BIN}, q{--version}) or die qq{$ENV{BIN}: $!};
+            my $got = <$bin>;
+            close($bin);
+            $got = defined $got ? $got : q{};
+            chomp $got;
+            index($got, $want) >= 0
+              or die qq{ERROR: the binary printed "$got", which does not contain $want. Version control was disabled, so there is no recorded version.\n};
+            index($got, q{+dirty}) < 0
+              or die qq{ERROR: the binary printed "$got". The tree was dirty at build time, which means the checkout was not the tag, or the build artefacts are not ignored.\n};
+            print qq{$ENV{BIN} reports $got\n};
+          '
 
   release:
     runs-on: fedora
+    timeout-minutes: 15
     needs: build
     permissions:
+      # contents: read is required for the checkout: a job that declares any
+      # permissions gets a token scoped to exactly those, and releases: write
+      # alone leaves the fetch with no read access, which Gitea answers with
+      # a 404 "Repository not found". Verified on the instance 2026-09-16.
+      contents: read
       releases: write
     steps:
       - uses: actions/checkout@v7
@@ -77,81 +202,125 @@ jobs:
         with:
           path: dist
 
-      - name: Extract CHANGELOG section
+      - name: Install Perl
+        run: dnf install -y perl
+
+      - name: Extract the CHANGELOG section
         env:
           VERSION: ${{ gitea.ref_name }}
         run: |
-          set -euo pipefail
+          # Each step derives what it needs from the tag, so no value has to travel between
-          VERSION_NO_V="${VERSION#v}"
+          # jobs.
+          perl -e '
+            my $v = $ENV{VERSION} // q{};
+            $v =~ s{^v}{};
+            open(my $vout, q{>}, q{version-no-v.txt}) or die qq{version-no-v.txt: $!};
+            print $vout $v;
+            close($vout);
+            open(my $in, q{<}, q{CHANGELOG.md}) or die qq{CHANGELOG.md: $!};
+            my @lines = <$in>;
+            close($in);
+            my ($start, $end) = (-1, scalar @lines);
+            for my $i (0 .. $#lines) {
+              if ($start < 0) { $start = $i if $lines[$i] =~ m{^##\s+\[\Q$v\E\]} }
+              elsif ($lines[$i] =~ m{^##\s+\[}) { $end = $i; last }
+            }
+            $start >= 0 or die qq{ERROR: no CHANGELOG section for $v, expected a heading like: ## [$v] - YYYY-MM-DD\n};
+            my @body = grep { m{\S} } @lines[$start + 1 .. $end - 1];
+            @body or die qq{ERROR: the CHANGELOG section for $v is empty\n};
+            open(my $out, q{>}, q{release-body.md}) or die qq{release-body.md: $!};
+            print $out @body;
+            close($out);
+            printf qq{notes for %s: %d lines\n}, $v, scalar @body;
+          '
 
-          sed -n "/^## \[${VERSION_NO_V}\] /,/^## \[/p" CHANGELOG.md \
+      - name: Build the release request
-            | sed '$d' \
+        run: |
-            | tail -n +2 \
+          perl -e '
-            > release-body.md
+            open(my $vin, q{<}, q{version-no-v.txt}) or die qq{version-no-v.txt: $!};
+            my $v = <$vin>;
+            close($vin);
+            chomp $v;
+            open(my $in, q{<:raw}, q{release-body.md}) or die qq{release-body.md: $!};
+            my $body = do { local $/; <$in> };
+            close($in);
+            # Byte-oriented escaping: JSON is UTF-8, so non-ASCII passes through and only the
+            # characters JSON forbids are rewritten.
+            $body =~ s/([\\"])/\\$1/g;
+            $body =~ s/\t/\\t/g;
+            $body =~ s/\r//g;
+            $body =~ s/\n/\\n/g;
+            $body =~ s/([\x00-\x08\x0b\x0c\x0e-\x1f])/sprintf(q{\u%04x}, ord($1))/ge;
+            my $json = sprintf(qq{{"tag_name":"v%s","name":"v%s","body":"%s","draft":false,"prerelease":false}}, $v, $v, $body);
+            open(my $out, q{>}, q{release.json}) or die qq{release.json: $!};
+            print $out $json;
+            close($out);
+            print qq{release.json written for v$v\n};
+          '
 
-          if [ ! -s release-body.md ]; then
+      - name: Create the release
-            echo "ERROR: no CHANGELOG section found for ${VERSION_NO_V}"
-            echo "Expected a heading like: ## [${VERSION_NO_V}] — YYYY-MM-DD"
-            exit 1
-          fi
-
-      - name: Create release
         env:
           GITEA_TOKEN: ${{ secrets.GITEA_TOKEN }}
           GITEA_SERVER_URL: ${{ gitea.server_url }}
           GITEA_REPOSITORY: ${{ gitea.repository }}
-          GITEA_REF_NAME: ${{ gitea.ref_name }}
         run: |
-          set -euo pipefail
+          perl -e '
-
+            my @cmd = (q{curl}, q{-sS}, q{-o}, q{response.json}, q{-w}, q{%{http_code}},
-          BODY=$(sed -e 's/\\/\\\\/g' -e 's/"/\\"/g' -e 's/\t/\\t/g' -e 's/\r//g' release-body.md | sed ':a;N;$!ba;s/\n/\\n/g')
+              q{-H}, qq{Authorization: token $ENV{GITEA_TOKEN}},
-          BODY="\"${BODY}\""
+              q{-H}, q{Content-Type: application/json},
-
+              q{-X}, q{POST},
-          response=$(curl -sS -w '\n%{http_code}' \
+              qq{$ENV{GITEA_SERVER_URL}/api/v1/repos/$ENV{GITEA_REPOSITORY}/releases},
-            -H "Authorization: token ${GITEA_TOKEN}" \
+              q{--data-binary}, q{@release.json});
-            -H "Content-Type: application/json" \
+            open(my $curl, q{-|}, @cmd) or die qq{curl: $!};
-            -X POST \
+            my $code = <$curl>;
-            "${GITEA_SERVER_URL}/api/v1/repos/${GITEA_REPOSITORY}/releases" \
+            my $ok = close($curl);
-            -d "{\"tag_name\":\"${GITEA_REF_NAME}\",\"name\":\"${GITEA_REF_NAME}\",\"body\":${BODY},\"draft\":false,\"prerelease\":false}")
+            my $exit = $? >> 8;
-
+            $code = defined $code ? $code : q{};
-          http_code=$(echo "$response" | tail -1)
+            $ok or die qq{ERROR: curl failed (exit $exit) calling $ENV{GITEA_SERVER_URL}\n};
-          payload=$(echo "$response" | sed '$d')
+            open(my $r, q{<:raw}, q{response.json}) or die qq{response.json: $!};
-
+            my $body = do { local $/; <$r> };
-          echo "HTTP ${http_code}"
+            close($r);
-          if [ "$http_code" != "201" ]; then
+            $code eq q{201} or die qq{ERROR: the release was not created, HTTP $code: $body\n};
-            echo "Failed to create release: ${payload}"
+            $body =~ m{"id"\s*:\s*([0-9]+)} or die qq{ERROR: no release id in the response: $body\n};
-            exit 1
+            open(my $o, q{>}, q{release-id.txt}) or die qq{release-id.txt: $!};
-          fi
+            print $o $1;
-
+            close($o);
-          RELEASE_ID=$(echo "$payload" | grep -oE '"id"[[:space:]]*:[[:space:]]*[0-9]+' | head -1 | grep -oE '[0-9]+')
+            print qq{release id $1\n};
-          echo "Created release ID=${RELEASE_ID}"
+          '
-          printf '%s' "${RELEASE_ID}" > release-id.txt
 
       - name: Upload assets
         env:
           GITEA_TOKEN: ${{ secrets.GITEA_TOKEN }}
           GITEA_SERVER_URL: ${{ gitea.server_url }}
           GITEA_REPOSITORY: ${{ gitea.repository }}
-          GITEA_REF_NAME: ${{ gitea.ref_name }}
         run: |
-          set -euo pipefail
+          perl -e '
-          RELEASE_ID=$(cat release-id.txt)
+            open(my $f, q{<}, q{release-id.txt}) or die qq{release-id.txt: $!};
-
+            my $id = <$f>;
-          for binary in dist/gasm-*/gasm-*; do
+            close($f);
-            [ -f "$binary" ] || continue
+            chomp $id;
-            fname=$(basename "$binary")
+            my @files = grep { -f $_ } glob(q{dist/*/*});
-            echo "Uploading ${fname}..."
+            @files or die qq{ERROR: no assets under dist/\n};
-            http_code=$(curl -sS -o /dev/null -w '%{http_code}' \
+            my $bad = 0;
-              -H "Authorization: token ${GITEA_TOKEN}" \
+            for my $path (@files) {
-              -H "Content-Type: application/octet-stream" \
+              (my $name = $path) =~ s{.*/}{};
-              -X POST \
+              my @cmd = (q{curl}, q{-sS}, q{-o}, q{/dev/null}, q{-w}, q{%{http_code}},
-              --data-binary "@${binary}" \
+                q{-H}, qq{Authorization: token $ENV{GITEA_TOKEN}},
-              "${GITEA_SERVER_URL}/api/v1/repos/${GITEA_REPOSITORY}/releases/${RELEASE_ID}/assets?name=${fname}")
+                q{-H}, q{Content-Type: application/octet-stream},
-            echo "  HTTP ${http_code}"
+                q{-X}, q{POST}, q{--data-binary}, qq{@$path},
-            if [ "$http_code" != "201" ]; then
+                qq{$ENV{GITEA_SERVER_URL}/api/v1/repos/$ENV{GITEA_REPOSITORY}/releases/$id/assets?name=$name});
-              echo "Failed to upload ${fname}"
+              open(my $curl, q{-|}, @cmd) or die qq{curl: $!};
-              exit 1
+              my $code = <$curl>;
-            fi
+              my $ok = close($curl);
-          done
+              my $exit = $? >> 8;
-
+              $code = defined $code ? $code : q{};
-          echo "Release ${GITEA_REF_NAME} is live."
+              unless ($ok) {
+                printf qq{%s: curl failed (exit %d)\n}, $name, $exit;
+                $bad = 1;
+                next;
+              }
+              printf qq{%s: HTTP %s\n}, $name, $code;
+              $bad = 1 if $code ne q{201};
+            }
+            exit($bad ? 1 : 0);
+          '

.gitea/workflows/test.yml

@@ -1,4 +1,17 @@
-# Test — gasm-devkit. Runs on push and pull request to development.
+# Test, Go. Push and pull request to development. Never on main.
+#
+# The gates are the ones the justfile's `gates` recipe runs, minus race: the shared
+# runner box cannot afford the race detector on every push, so it lives in race.yml.
+# The box is one core and 2 GB beside Gitea, so parallelism is bounded on purpose and
+# everything runs in one job. Extra jobs would duplicate the checkout, the Go setup and
+# the dependency download three times without buying any parallelism.
+#
+# Every step is one command, so the step that fails is the gate that failed, and no shell
+# option has to be trusted for the run to stop. The scripted steps are Perl, not shell and
+# not Python: Perl behaves the same on both runner images, there is no bashism to trip over
+# on ash, and it is one language instead of two. The Perl uses builtins only, because
+# Fedora packages the Perl modules separately and nothing beyond `perl` itself may be
+# assumed present.
 name: Test
 
 on:
@@ -7,90 +20,83 @@ on:
   pull_request:
     branches: [development]
 
+env:
+  # One core: parallelism buys no speed here and costs memory the box does not have.
+  GOFLAGS: -p=1
+  GOMAXPROCS: "2"
+
+# A superseded run of the same ref is cancelled instead of queueing behind one that
+# no longer matters. Verified on Gitea 1.27.1 on 2026-09-17: a queued run whose ref
+# moved on is cancelled before it ever reaches the runner, while a run already
+# dispatched there runs to completion.
+concurrency:
+  group: ${{ gitea.workflow }}-${{ gitea.ref }}
+  cancel-in-progress: true
+
 jobs:
-  vet:
-    runs-on: fedora
-    steps:
-      - uses: actions/checkout@v7
-
-      - uses: actions/setup-go@v6
-        with:
-          go-version: "1.27"
-
-      - name: Download dependencies
-        run: go mod download
-
-      - name: gofmt
-        run: |
-          set -euo pipefail
-          unformatted=$(gofmt -l .)
-          if [ -n "$unformatted" ]; then
-            echo "These files need gofmt:"
-            echo "$unformatted"
-            exit 1
-          fi
-
-      - name: go vet
-        run: go vet ./...
-
   test:
     runs-on: fedora
-    needs: vet
+    timeout-minutes: 10
     steps:
       - uses: actions/checkout@v7
 
       - uses: actions/setup-go@v6
         with:
-          go-version: "1.27"
+          # The module is the source of truth for the version, so it cannot drift.
+          go-version-file: go.mod
+          cache: true
 
-      - name: Download dependencies
+      - name: Install Perl
-        run: go mod download
+        # The runner images are minimal and Perl is not guaranteed. The install is a
-
+        # no-op where it is already present; drop this step once verified on the box.
-      - name: Install gcc
+        run: dnf install -y perl
-        run: dnf install -y gcc
-
-      - name: go test -race
-        run: go test -race -count=1 ./...
-
-      - name: Coverage gate — 80 % minimum
-        run: |
-          set -euo pipefail
-          # Exclude packages inherently untestable without hardware:
-          # debug — interactive ptrace, requires a live process
-          # cmd/gasm — CLI glue, covered by integration tests
-          go test -coverprofile=coverage.out \
-            sourcedock.dev/petrbalvin/gasm-devkit/arch \
-            sourcedock.dev/petrbalvin/gasm-devkit/asm \
-            sourcedock.dev/petrbalvin/gasm-devkit/ast \
-            sourcedock.dev/petrbalvin/gasm-devkit/format \
-            sourcedock.dev/petrbalvin/gasm-devkit/lexer \
-            sourcedock.dev/petrbalvin/gasm-devkit/lint \
-            sourcedock.dev/petrbalvin/gasm-devkit/lsp \
-            sourcedock.dev/petrbalvin/gasm-devkit/parser \
-            sourcedock.dev/petrbalvin/gasm-devkit/token \
-            sourcedock.dev/petrbalvin/gasm-devkit/verify
-          coverage=$(go tool cover -func=coverage.out | awk '/^total:/ { gsub("%", "", $3); print $3 }')
-          echo "Total coverage: ${coverage}%"
-          if awk -v c="$coverage" 'BEGIN { exit !(c+0 < 80) }'; then
-            echo "ERROR: coverage ${coverage}% is below the 80% threshold"
-            exit 1
-          fi
-
-  build:
-    runs-on: fedora
-    needs: test
-    steps:
-      - uses: actions/checkout@v7
-
-      - uses: actions/setup-go@v6
-        with:
-          go-version: "1.27"
-
-      - name: Download dependencies
-        run: go mod download
 
+      # The steps follow the `gates` order of the justfile contract: build, format,
+      # vet, test. The vet gate is go vet and go fix -diff, two steps here.
       - name: Build
-        run: go build -ldflags="-s -w" -o bin/gasm ./cmd/gasm
+        run: go build ./...
 
-      - name: Smoke test
+      - name: Format
-        run: ./bin/gasm --version
+        run: |
+          perl -e '
+            open(my $g, q{-|}, q{gofmt}, q{-l}, q{.}) or die qq{gofmt: $!};
+            my @bad = <$g>;
+            close($g);
+            print @bad;
+            exit(@bad ? 1 : 0);
+          '
+
+      - name: Vet
+        run: go vet ./...
+
+      - name: Modernise
+        # Exits non-zero when it has something to rewrite, so it needs no output capture.
+        run: go fix -diff ./...
+
+      - name: Tests
+        # The suite must be fast: a push pipeline that cannot finish in a few minutes moves
+        # its heavy part behind a dispatch. The inner timeout matches the job's, so a
+        # hanging test reports its own goroutine dump rather than a silent job kill.
+        # The pattern is `packages` in the project's justfile: the logic packages, since a
+        # thin cmd/ would drag the total under the floor. release.yml runs the same
+        # command, so the floor is the same number everywhere. ./verify/... carries the
+        # live oracle-parity comparison against `go tool asm` (the TestGroundTruth
+        # suites); the runner's Go setup provides both the tool and GOROOT.
+        run: go test -count=1 -timeout 10m -coverprofile=coverage.out ./arch/... ./asm/... ./ast/... ./disasm/... ./format/... ./lexer/... ./lint/... ./lsp/... ./parser/... ./token/... ./verify/...
+
+      - name: Oracle parity
+        # Re-run the live go-tool-asm comparison as its own step so that a parity
+        # regression names the gate that failed instead of hiding inside the suite.
+        run: go test -count=1 -timeout 10m -run 'TestGroundTruth' ./verify/...
+
+      - name: Coverage floor
+        run: |
+          perl -e '
+            open(my $c, q{-|}, q{go}, q{tool}, q{cover}, q{-func=coverage.out}) or die qq{cover: $!};
+            my $total;
+            while (my $l = <$c>) { $total = $1 if $l =~ m{^total:\s+\S+\s+([0-9.]+)%} }
+            close($c);
+            die qq{no total line in coverage.out\n} unless defined $total;
+            printf qq{Total coverage: %s%%\n}, $total;
+            exit($total < 80 ? 1 : 0);
+          '

.gitignore

@@ -1,24 +1,13 @@
-# Metadata (always first, per repo convention)
 .idea/
 .zcode/
-.mimocode/
 
-# Binaries
+# Build output
-/gasm
 /bin/
-*.exe
+/gasm
-
-# Test and coverage artefacts
 coverage.out
 *.test
 
-# Crash dumps
+# Crash dumps from the emulator runs
 core
 core.*
 *.core
-
-# Scratch / temporary work
-_scratch/
-
-# ZCode workspace
-.zcode

CHANGELOG.md

@@ -3,15 +3,170 @@
 All notable changes to gasm-devkit are documented here.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
-and this project adheres to [Conventional Commits](https://www.conventionalcommits.org/).
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [development]
 
 ### Added
 
--
+- **Indirect JMP and CALL on all four architectures.**  `JMP AX`,
+  `CALL AX`, `JMP (BX)` and the memory forms encode at byte parity with
+  the toolchain (FF /2 and FF /4 on amd64); arm64 lowers `JMP (R0)` to
+  BR and accepts the raw BR/BLR spellings; riscv64 lowers `JMP (X5)` to
+  JALR; loong64 accepts the raw `JIRL rd, rj, off` spelling the Go
+  assembler cannot express.  A frameless amd64 function containing a
+  CALL now receives the toolchain's forced base-pointer frame.  The
+  verify trampolines join the ground-truth lists, and a lint check for
+  control flow through registers and memory extends to the new forms.
+- **`gasm asm -GOARCH` and `gasm diff -GOARCH`.**  The target
+  architecture can be named explicitly instead of inferred from the
+  file-name suffix, which is how the suffix-less majority of GOROOT's
+  `.s` files (cpu_x86.s, stub.s, ...) become assemblable.
+- **`gasm audit-instructions --corpus [dir]`.**  Assembles every `.s`
+  file under a directory (default GOROOT/src) with the gasm encoder
+  only: suffixed files for their architecture, suffix-less files for
+  all four, as a GOARCH build would.  Reports the headline number (108
+  of 627 GOROOT files, 17.2 %, assemble for every target architecture,
+  against 23 in the previous release), the per-architecture pass rates
+  and the most common failure reasons with a representative file each,
+  which drive the encodability backlog by frequency.
+- **Fuzz targets for the parser and the formatter.**  FuzzParse (no
+  panic, always a usable file) and FuzzFormatIdempotency (formatting
+  twice equals formatting once; clean input stays clean) seed
+  themselves from the repository's kernels, so the plain test suite
+  replays every seed in CI and `just fuzz` runs the mutation engine on
+  demand.
+- **Oracle parity as its own CI step.**  The push pipeline already ran
+  the live go-tool-asm comparison inside the suite; a dedicated step
+  now names that gate when it fails.
+- **Man pages.**  docs/man carries gasm(1) and one page per command,
+  written in roff: synopsis, description, every flag with its default,
+  exit status, worked examples and cross-references.
+  `just install-man` compresses them into ~/.local/share/man (MANDIR
+  overrides) and `just uninstall-man` removes them.  A test builds the
+  binary and compares every command's `-h` output with its page, so the
+  pages cannot drift from the CLI.
 
-## [0.32.0] — 2026-08-31
+### Changed
+
+- **Canonical just recipes.**  `just gates` is the definition of done
+  (build, fmt-check, vet, test, race).  `install` now builds and copies
+  the binary into `~/.local/bin` (`BINDIR` overrides) instead of
+  downloading module dependencies, and `install-bin` is gone.  The test
+  gate sweeps the logic packages (arch through verify; the hardware-bound
+  `debug` and the thin `cmd/gasm` sit outside it), so the coverage floor
+  is computed over the product code and the number is identical locally
+  and in CI.  `fuzz` requires its target package.
+- **The reported version comes from the build.**  `gasm --version`
+  prints the version the toolchain recorded: the tag on a tagged
+  checkout, a pseudo-version naming the commit below one, `+dirty` on a
+  dirty tree and `(devel)` outside version control.  Nothing is
+  injected with `-ldflags -X` any more.
+- **CI realigned with the gate set.**  The push pipeline runs the gates
+  minus race in one job, in the `gates` order, with a cached Go setup and
+  the module as the version source; a superseded run of the same branch
+  is cancelled instead of queueing; every `go test` runs under a
+  ten-minute bound that matches its job's; the race detector moved to a
+  hand-dispatched workflow and runs in the local gate before a tag is
+  cut, never on a push or a tag; the release builds without injection and
+  its smoke test requires the recorded tag and rejects `+dirty`.
+- **The documents follow the standard set.**  `docs/ARCHITECTURE.md` is
+  organised as Overview, Packages, Data flow, State and lifetime and
+  Dependencies, and carries a sequence diagram of the assembly path;
+  `docs/DEVELOPMENT.md` lists every recipe in one table and documents the
+  coverage floor, the CI and the release flow; `docs/CLI.md` gives the
+  synopsis, the commands, every flag with its default, the exit codes and
+  worked examples; `CONTRIBUTING.md` carries the Contributor terms and
+  states the commit trailer form, the one-logical-change rule and the
+  licence header rule.  The repository's own assembly (the `verify`
+  trampolines and the test kernels) is in `gasm fmt` canonical form.
+- **The README states the project's purpose and status.**  It opens with
+  a warning that the tool is an experiment under active development,
+  version 0.x.x, free to change without warning, with 1.0.0 far off,
+  and already in active use on real assembly work.  It describes both
+  goals (tooling for Plan 9 assembly, and Plan 9 assembly outside the
+  Go toolchain), argues the case for the syntax in a new Why Plan 9
+  assembly section, and carries a Direction section: extended
+  instruction support, full GOOBJ and ELF compilation, Linux and
+  FreeBSD, and the four architectures.
+
+### Fixed
+
+- **riscv64 JALR silently jumped to the wrong register.**  The trampoline
+  form `JALR X0, 0(X5)` read the memory operand's base as the destination,
+  encoding a jump to X0 with no diagnostic; the destination is the first
+  operand.  The leaf detection shared the confusion, so affected functions
+  also grew a bogus prologue.  `JALR X0, 0(X1)` as written in the verify
+  trampoline was mis-encoded since its introduction.
+- **DATA lines demanded their GLOBL first.**  collectData processed the
+  declarations in file order, but the Plan 9 convention puts every DATA
+  line before its symbol's GLOBL; correctly ordered files (most of
+  GOROOT's) failed with "no matching GLOBL".  Two passes: symbols are
+  registered before initialisers are applied.
+- **The formatter lost idempotency on degenerate lines.**  Illegal tokens
+  survived into the output, a label sharing its line with a
+  non-instruction split into a line the parser rejects, stray-operand
+  lines entered the alignment width computation, and rendered `/ *`,
+  `> >` sequences re-lexed as comments and shifts.  The label, width and
+  spacing rules now agree between passes.
+
+## [0.33.0] - 2026-09-14
+
+### Added
+
+- **Stack-split guards in `gasm asm`.**  Every framed function now gets
+  the morestack prologue check and the trailing morestack block
+  (`CALL runtime.morestack_noctxt`), byte-identical to the toolchain's
+  `stacksplit` output on all four architectures: the small, medium and
+  big frame classes, auto-NOSPLIT leaves, the materialised constants of
+  large frames (arm64 `R27`, riscv64 `X31`, loong64 `R30`) and the
+  arm64 extrasize rule.  Assembled objects are therefore linkable for
+  split functions, not only `NOSPLIT` leaves.
+- **`gasm dis`.**  Standalone disassembly through `golang.org/x/arch`:
+  a `.s` file is assembled and listed per `TEXT` function with local
+  labels at their real offsets, or raw bytes from a file or stdin are
+  disassembled linearly (`-a` selects the architecture).  The debugger
+  shares the same decoder instead of carrying its own.
+- **`gasm fmt -l` and `-d`.**  Check mode lists files whose formatting
+  differs; diff mode prints a unified diff from the project's own
+  LCS-based differ, with GNU header semantics.
+- **LSP cross-file navigation.**  Go-to-definition and find references
+  fall back from local labels to the `TEXT` functions of every open
+  document, and rename follows the same cross-file matching.
+- **Large frame offsets on riscv64 and arm64.**  Frame-relative loads
+  and stores beyond the signed 12-bit immediate range materialise the
+  address through the toolchain temp register (riscv64 `X31`, arm64
+  `R27`) instead of silently truncating the offset (riscv64) or
+  rejecting the instruction (arm64); arm64 frame sizes now add the
+  toolchain's extrasize exactly (+8 when the frame leaves an alignment
+  gap, +16 when it is already aligned).
+- **Tail calls `JMP sym(SB)`** on all four architectures (amd64 `E9`,
+  arm64 `B`, riscv64 `JAL X0`, loong64 `B`) with the call relocation.
+- **Live oracle-parity tests.**  Kernel files covering every guard
+  class, large-offset pattern and tail call are assembled by gasm and
+  by the installed `go tool asm` and compared byte-for-byte on all four
+  architectures, alongside the existing pinned-byte tests.
+
+### Fixed
+
+- The v0.32.0 review findings: the parser rejects malformed `TEXT`
+  frames and parses signed frame sizes; amd64 frame adjustments above
+  127 bytes encode with imm32; arm64 and loong64 relocation encodings
+  match the toolchain; the linter guards unnamed `TEXT` directives and
+  refreshes its textflag table; the LSP recovers from handler panics
+  and decodes client URIs; watchpoint slot state moved into the debug
+  session; dead verify code removed; em and en dashes replaced across
+  sources.
+- `gasm asm --format goobj`: internal calls to `TEXT` symbols of the
+  same file resolve on every architecture (the reference check accepted
+  only the amd64 call kind).
+- `gasm asm --format elf` on loong64: branch relocations now map to
+  `R_LARCH_B26` instead of falling into `R_LARCH_PCALA_HI20`.
+- arm64 large-prologue `ADD`/`SUB` use the extended-register encoding
+  the toolchain picks, and the morestack block saves the link register
+  with the toolchain's `OR` form on loong64.
+
+## [0.32.0] - 2026-08-31
 
 ### Added
 
@@ -162,7 +317,7 @@ and this project adheres to [Conventional Commits](https://www.conventionalcommi
   outputs and operand strictness with `go tool asm`.
 - **asm help text.**  Updated to list arm64 as a supported architecture.
 
-## [0.31.1] — 2026-08-20
+## [0.31.1] - 2026-08-20
 
 ### Fixed
 
@@ -170,9 +325,9 @@ and this project adheres to [Conventional Commits](https://www.conventionalcommi
   because the version variables in `justfile` and `cmd/gasm/main.go` were not
   bumped during the release commit.
 
-## [0.31.0] — 2026-08-20
+## [0.31.0] - 2026-08-20
 
-The arm64 encoder (Phase 5 — complete) ships with ELF64 and GOOBJ emission,
+The arm64 encoder (Phase 5; complete) ships with ELF64 and GOOBJ emission,
 verified byte-for-byte against `GOARCH=arm64 go tool asm` and linked into a
 real `go build`.  The encoder covers the full integer instruction set, FP
 arithmetic, conditional select, CRC32, and the MOV pseudo-instruction with
@@ -180,7 +335,7 @@ bitmask immediate encoding.  The project now requires Go 1.27.
 
 ### Added
 
-- **arm64 encoder (Phase 5 — complete).**  `gasm asm` can now assemble `_arm64.s`
+- **arm64 encoder (Phase 5; complete).**  `gasm asm` can now assemble `_arm64.s`
   files: the AArch64 integer instruction set with the MOV pseudo-instruction and
   its immediate-constant expansions (MOVZ/MOVN/MOVK for wide immediates, ORR with
   logical bitmask encoding for values like `$1`), data-processing (shifted
@@ -189,7 +344,7 @@ bitmask immediate encoding.  The project now requires Go 1.27.
   SB/global symbol references (ADRP+ADD pairs with `R_ADDRARM64` relocations),
   jump chain folding, and ELF64 emission (`gasm asm --format elf`).  Ground-truth
   verification against `GOARCH=arm64 go tool asm` matches byte-for-byte.  Phase 5
-  (the other architectures — RISC-V, LoongArch, arm64) is now complete.
+  (the other architectures; RISC-V, LoongArch, arm64) is now complete.
 
 ### Changed
 
@@ -197,7 +352,7 @@ bitmask immediate encoding.  The project now requires Go 1.27.
   The `R_DWTXTADDR_U4` relocation type is detected at runtime for backward
   compatibility.
 
-## [0.30.0] — 2026-08-13
+## [0.30.0] - 2026-08-13
 
 The LoongArch encoder (Phase 5) ships with ELF64 and GOOBJ emission, verified
 byte-for-byte against `GOARCH=loong64 go tool asm` and linked into a real
@@ -222,7 +377,7 @@ tracks four hardware watchpoint slots, and the toolkit is Linux-only.
 - **GOOBJ DWARF symbols.**  The GOOBJ emitters now write the per-function
   DWARF symbols the linker requires (the subprogram DIE and the `.debug_line`
   program, byte-identical to `cmd/asm`'s), and the pc-value table deltas are
-  in the architecture's MinLC units as the runtime expects — the amd64 link
+  in the architecture's MinLC units as the runtime expects; the amd64 link
   test now genuinely substitutes the gasm object, and the amd64/loong64
   end-to-end GOOBJ link tests pass.
 - **RISC-V GOOBJ emission via the shared emitter.**  RISC-V GOOBJ output is
@@ -291,7 +446,7 @@ tracks four hardware watchpoint slots, and the toolkit is Linux-only.
   `GOARCH=riscv64 go tool asm`.
 - **Debugger watchpoint slots.**  `gasm debug`'s `watch` command always used
   hardware watchpoint slot 0, so a second `watch` call silently overwrote
-  the first.  Watchpoint slots are now tracked in the `Session` (DR0–DR3);
+  the first.  Watchpoint slots are now tracked in the `Session` (DR0-DR3);
   `watch` picks the first free slot and reports an error if all four are in
   use, and `unwatch <slot>` clears one (no argument clears all).
 
@@ -303,7 +458,7 @@ tracks four hardware watchpoint slots, and the toolkit is Linux-only.
   disassembly at PC, memory-write, watchpoints, and source-line mapping are
   all shipped.
 
-## [0.29.0] — 2026-08-07
+## [0.29.0] - 2026-08-07
 
 RISC-V GOOBJ emission, YMM vector register display, named buffer allocation
 in the debugger, two new CLI commands (`diff`, `profile`), go-to-definition in
@@ -313,30 +468,30 @@ new CLI commands. A signature-parser fix corrects grouped Go parameters.
 
 ### Added
 
-- **RISC-V GOOBJ emission** — `gasm asm --format goobj` for RISC-V produces
+- **RISC-V GOOBJ emission**; `gasm asm --format goobj` for RISC-V produces
   linkable Go objects with funcdata, pc-value tables, and RISC-V relocation
   types (same format as amd64 GOOBJ, with the RISC-V architecture marker).
-- **`gasm diff`** — compare the machine code of two assembly files byte-for-byte;
+- **`gasm diff`**; compare the machine code of two assembly files byte-for-byte;
   shows which functions differ and the first few differing bytes.
-- **`gasm profile`** — show the basic-block structure of each function: labels,
+- **`gasm profile`**; show the basic-block structure of each function: labels,
   offsets, frame size, and NOSPLIT flag.
-- **LSP go-to-definition** — `textDocument/definition` navigates from a label
+- **LSP go-to-definition**; `textDocument/definition` navigates from a label
   reference to its definition.
-- **did-you-mean** — when the RISC-V assembler encounters an undefined label, it
+- **did-you-mean**; when the RISC-V assembler encounters an undefined label, it
   suggests the closest existing label using Levenshtein distance.
-- **YMM vector register display** — `regs` in the debugger now shows YMM
+- **YMM vector register display**; `regs` in the debugger now shows YMM
   registers via `PTRACE_GETFPREGS` (falls back to XMM when XSAVE is unavailable).
-- **Named buffer allocation** — `gasm debug --buf name:size:pattern` allocates
+- **Named buffer allocation**; `gasm debug --buf name:size:pattern` allocates
   buffers in the debuggee filled with `zero`, `ones`, `seq`, or a hex pattern;
   buffer pointers are placed into the argument block at the matching positions.
-- **Crash input storage** — `FuzzResult.CrashInput` stores the input that caused
+- **Crash input storage**; `FuzzResult.CrashInput` stores the input that caused
   a crash or mismatch for reproducibility.
-- **ABI + fuzz combined** — `gasm verify --fuzz` now runs ABI checks (sentinel
+- **ABI + fuzz combined**; `gasm verify --fuzz` now runs ABI checks (sentinel
   registers, canary, stack bounds) alongside differential fuzz testing.
-- **`gasm diff --map`** — compare functions whose names differ between files
+- **`gasm diff --map`**; compare functions whose names differ between files
   (e.g. `--map wideCopyAVX2=wideCopyAVX512` pairs two variants regardless
   of suffix). Unmapped functions fall back to the original name match.
-- **`gasm verify --call`** — invoke a single function with user-supplied buffers
+- **`gasm verify --call`**; invoke a single function with user-supplied buffers
   (`--buf name:size:pattern`) instead of the smoke/abi/fuzz sweeps. Patterns:
   `zero`, `ones`, `seq`, or a hex blob. Useful for partial functions (e.g.
   decoders) that crash on random input but should succeed on valid data.
@@ -346,23 +501,23 @@ new CLI commands. A signature-parser fix corrects grouped Go parameters.
 
 ### Fixed
 
-- **Signature parser** — grouped Go parameters like `dst, src []byte` are now
+- **Signature parser**; grouped Go parameters like `dst, src []byte` are now
   parsed correctly (both get type `[]byte`). Previously the first name was
   treated as its own type (`dst` with size 8), causing wrong ABI0 arg-block
   layout in both `verify --call` and the fuzzer.
-- **Flaky JIT tests** — `runtime.KeepAlive` guards and package-level buffers
+- **Flaky JIT tests**; `runtime.KeepAlive` guards and package-level buffers
   prevent GC from collecting heap objects whose addresses were passed to JIT
   code via `unsafe.Pointer`; all verify tests pass 100/100 under `-race`.
 
 ### Changed
 
-- **Removed external kernel test dependencies** — the verify test suite no
+- **Removed external kernel test dependencies**; the verify test suite no
   longer references production kernels from the separate go-libraries project.
   The remaining test suite uses only `testdata/verify/*.s` kernels, which are
   part of this repository.  Coverage is identical locally and in CI (80.3 %).
 
 
-## [0.28.0] — 2026-08-03
+## [0.28.0] - 2026-08-03
 
 RISC-V encoder: full RV64IMAFDC instruction set with RVC compression, MOV
 pseudo-instruction, SB/global symbol references, ELF64 object emission, and
@@ -370,20 +525,20 @@ ground-truth verification against `GOARCH=riscv64 go tool asm`.
 
 ### Added
 
-- **RISC-V encoder** — RV64I, RV64M, RV64A, RV64F/D, FMA, CSR, JALR.
+- **RISC-V encoder**; RV64I, RV64M, RV64A, RV64F/D, FMA, CSR, JALR.
-- **MOV pseudo-instruction** — load, store, reg-to-reg, immediate, frame mapping.
+- **MOV pseudo-instruction**; load, store, reg-to-reg, immediate, frame mapping.
-- **RVC compression** — 22 compressed instruction types (C.LDSP, C.SDSP, C.FLDSP,
+- **RVC compression**; 22 compressed instruction types (C.LDSP, C.SDSP, C.FLDSP,
   C.FSDSP, C.ADDI, C.LI, C.LUI, C.ADDIW, C.MV, C.ADD, C.SUB, C.XOR, C.OR, C.AND,
   C.SLLI, C.SRLI, C.SRAI, C.ANDI, C.BEQZ, C.BNEZ, C.J, C.JR).
-- **SB/global symbols** — `MOV $sym(SB)`, `MOV sym(SB)`, `MOV rd, sym(SB)`
+- **SB/global symbols**; `MOV $sym(SB)`, `MOV sym(SB)`, `MOV rd, sym(SB)`
   encoded as AUIPC pairs with R_RISCV_PCREL_HI20/LO12 relocations.
-- **GLOBL/DATA** — data section layout in `AssembleFileRISCV`.
+- **GLOBL/DATA**; data section layout in `AssembleFileRISCV`.
-- **ELF64 emission** — `gasm asm --format elf` produces EM_RISCV objects
+- **ELF64 emission**; `gasm asm --format elf` produces EM_RISCV objects
   (.text, .data, .symtab, .rela.text).
-- **`gasm verify --ground-truth`** — byte-exact comparison against
+- **`gasm verify --ground-truth`**; byte-exact comparison against
   `GOARCH=riscv64 go tool asm`.
-- **`gasm verify --profile`** — function layout listing for RISC-V.
+- **`gasm verify --profile`**; function layout listing for RISC-V.
-- **CALL** — AUIPC + JALR pair encoding.
+- **CALL**; AUIPC + JALR pair encoding.
 
 ### Fixed
 
@@ -393,7 +548,7 @@ ground-truth verification against `GOARCH=riscv64 go tool asm`.
   (bit-interleaved format).
 
 
-## [0.27.0] — 2026-08-01
+## [0.27.0] - 2026-08-01
 
 Subprocess isolation for `--fuzz`: each function is fuzzed in its own child
 process, so a partial function (decoder) that faults on random garbage is
@@ -404,7 +559,7 @@ the parent.  CRASH is informational (exit 0); only MISMATCH is an error.
 
 - `gasm verify --fuzz` no longer crashes the process on partial functions.
 
-## [0.26.0] — 2026-07-31
+## [0.26.0] - 2026-07-31
 
 Universal differential fuzzing: `gasm verify --fuzz` needs no hand-written
 reference.  It parses the `// func` signature from the assembly source,
@@ -415,7 +570,7 @@ area bit-for-bit.
 
 ### Added
 
-- `verify`: `FuzzFunc` / `ExtractSignatures` / `parseFuncSig` — universal
+- `verify`: `FuzzFunc` / `ExtractSignatures` / `parseFuncSig`; universal
   differential fuzz driven by the conventional `// func` comment.  Each
   version gets its own buffer set (deep copy) so functions that write to
   their arguments (histogram increments) don't corrupt the other's input.
@@ -430,16 +585,16 @@ area bit-for-bit.
 over-copy paths read past the buffer on random garbage input.  Subprocess
 isolation (fork per function) is planned.  Use `--ground-truth` for decoders.
 
-## [0.25.0] — 2026-07-30
+## [0.25.0] - 2026-07-30
 
 Universal ground-truth verification: `gasm verify --ground-truth` assembles
 any `.s` file with both gasm and `go tool asm`, then compares the machine
 code byte-for-byte per function (relocation sites masked).  No hand-written
-reference needed — the Go toolchain IS the oracle.
+reference needed; the Go toolchain IS the oracle.
 
 ### Added
 
-- `verify`: `GroundTruth` — shells out to `go tool asm`, parses the GOOBJ
+- `verify`: `GroundTruth`; shells out to `go tool asm`, parses the GOOBJ
   output (minimal reader: block offsets, nonpkg symbol table, data index)
   and returns per-function code bytes.
 - `gasm verify --ground-truth`: compares gasm's output against the Go
@@ -448,11 +603,11 @@ reference needed — the Go toolchain IS the oracle.
   linker fills) are masked before comparison.
 - Verified: go-lz4 AVX2 2/2, go-flac AVX2 17/17 functions byte-identical.
 
-## [0.24.0] — 2026-07-29
+## [0.24.0] - 2026-07-29
 
 The full analyze family and stereo PCM decode are now differentially tested.
 15 of 17 go-flac AVX2 kernels have bit-for-bit differential coverage; the
-two remaining (autocorrAVX2 — FMA reassociation, lpcResidualAVX2 — complex
+two remaining (autocorrAVX2: FMA reassociation, lpcResidualAVX2: complex
 multi-arg) are deferred.
 
 ### Added
@@ -462,7 +617,7 @@ multi-arg) are deferred.
 - `verify`: `decodeStereo16AVX2` differential test (500 random interleaved
   stereo PCM buffers, both channels compared sample-by-sample).
 
-## [0.23.0] — 2026-07-28
+## [0.23.0] - 2026-07-28
 
 The analyze family and 24-bit PCM decode join the differential suite.
 
@@ -474,7 +629,7 @@ The analyze family and 24-bit PCM decode join the differential suite.
 - `verify`: `decodeMono24AVX2` differential test (500 random 24-bit PCM
   buffers, sign-extension compared sample-by-sample).
 
-## [0.22.0] — 2026-07-27
+## [0.22.0] - 2026-07-27
 
 The remaining go-flac encoder kernels join the differential suite.
 
@@ -488,39 +643,39 @@ The remaining go-flac encoder kernels join the differential suite.
   loop).
 
 
-## [0.21.0] — 2026-07-26
+## [0.21.0] - 2026-07-26
 
 Differential testing extended to all four production kernels and the CLI
 exposes the full dynamic-analysis toolkit.
 
 ### Added
 
-- `verify`: go-flac AVX2 differential tests — `decodeMono16AVX2` (500
+- `verify`: go-flac AVX2 differential tests; `decodeMono16AVX2` (500
   random PCM buffers), `pack16AVX2` (500 random int32→int16 packings) and
   all four decorrelation kernels (200 iterations each: left-side, side-right,
   mid-side, interleave) compared bit-for-bit against the portable Go
   references.
-- `verify`: go-lz4 AVX-512 differential tests — `decodeBlockAVX512` (3 000
+- `verify`: go-lz4 AVX-512 differential tests; `decodeBlockAVX512` (3 000
-  fuzzed LZ4 blocks + known answers) and `wideCopyAVX512` (0–1024 bytes)
+  fuzzed LZ4 blocks + known answers) and `wideCopyAVX512` (0-1024 bytes)
   against the same portable oracle as the AVX2 suite.
 - `gasm verify --abi`: runs each NOSPLIT function with sentinel registers
   and a red-zone canary, reporting violations.
 - `gasm verify --profile`: lists the static basic-block count per function.
 
-## [0.20.0] — 2026-07-25
+## [0.20.0] - 2026-07-25
 
 Coverage profiling: the third pillar of Phase 3.  Static basic-block
 enumeration from the assembler's label map, combined with multi-input path
-diversity measurement — how many observationally distinct execution paths a
+diversity measurement; how many observationally distinct execution paths a
 test corpus exercises.
 
 ### Added
 
-- `verify`: `Kernel.Blocks` / `Kernel.BlockCount` — enumerate basic blocks
+- `verify`: `Kernel.Blocks` / `Kernel.BlockCount`; enumerate basic blocks
   from the assembler's local-label map (every jump target is a block
   boundary; the function entry is always a block).  `decodeBlockAVX2` has
   27 blocks.
-- `verify`: `Kernel.ProfilePaths` — run the function with a corpus of
+- `verify`: `Kernel.ProfilePaths`; run the function with a corpus of
   argument blocks and collect distinct output fingerprints (the result
   words); reports path diversity as a lower bound on code coverage.
 
@@ -532,7 +687,7 @@ rt_sigaction handlers fragile in a Go process.  The static + path-diversity
 approach delivers the project's goal (proving the SIMD path and tail handling
 execute) without fighting the runtime.
 
-## [0.19.0] — 2026-07-24
+## [0.19.0] - 2026-07-24
 
 Runtime ABI checks: the second pillar of Phase 3.  The JIT trampoline now
 has an ABI-checking variant that sets sentinels in the callee-saved registers
@@ -542,41 +697,41 @@ detects any illegal write below the stack pointer.
 
 ### Added
 
-- `verify`: `CallChecked` / `Kernel.CallFuncChecked` — ABI-checking JIT call
+- `verify`: `CallChecked` / `Kernel.CallFuncChecked`; ABI-checking JIT call
   with sentinel registers and red-zone canary; returns an `ABIReport`
   (BPClobbered, R14Clobbered, RedZoneHit).
-- `verify`: the raw `leaveJITCheckedRaw` trampoline — a TEXT symbol with no
+- `verify`: the raw `leaveJITCheckedRaw` trampoline; a TEXT symbol with no
   ABIInternal wrapper (address obtained via GLOBL/DATA), so the JIT
   function's RET lands directly in the check code and sees the registers
   exactly as the function left them.
 - Tests: deliberate BP/R14 clobberers detected; both go-lz4 kernels
   confirmed ABI-clean (BP preserved, R14 preserved, red zone intact).
 
-## [0.18.0] — 2026-07-23
+## [0.18.0] - 2026-07-23
 
 Differential testing: the JIT-assembled go-lz4 `decodeBlockAVX2` kernel is
-fuzzed against a portable Go reference — 5 000 valid LZ4 blocks compared
+fuzzed against a portable Go reference; 5 000 valid LZ4 blocks compared
 bit-for-bit, plus 2 000 hostile (random garbage) inputs with matching error
 codes.  This is the automated form of the project's bit-identical contract.
 
 ### Added
 
-- `verify`: differential fuzz tests — a random LZ4 block generator produces
+- `verify`: differential fuzz tests; a random LZ4 block generator produces
   valid blocks (literals, overlapping matches, extension bytes) and the
   JIT-assembled kernel's output is compared byte-for-byte against a portable
   Go decoder; a hostile-input suite confirms error-code agreement on random
   garbage (no crashes, same classification).
 
-## [0.17.0] — 2026-07-22
+## [0.17.0] - 2026-07-22
 
 Phase 3 begins: dynamic analysis.  A JIT execution substrate that assembles
-Plan 9 amd64 kernels into executable memory and calls them directly — pure Go
+Plan 9 amd64 kernels into executable memory and calls them directly; pure Go
 (stdlib only, `syscall.Mmap` + an assembly trampoline), no cgo, no external
 toolchain.
 
 ### Added
 
-- `verify` package: JIT infrastructure — `Map` copies machine code into a
+- `verify` package: JIT infrastructure; `Map` copies machine code into a
   W^X memory mapping, `Call` invokes it through an ABI0 trampoline that
   switches to a prepared stack and back.  `Load`/`LoadSource`/`LoadAST`
   parse, assemble and map a `.s` file in one step; `Kernel.CallFunc`
@@ -585,34 +740,34 @@ toolchain.
   available functions; with `-smoke`, calls each NOSPLIT function with
   zeroed arguments to confirm the trampoline works end-to-end.
 - Integration tests: the go-lz4 `decodeBlockAVX2` and `wideCopyAVX2`
-  kernels (699 and 146 bytes) assemble, map and execute correctly —
+  kernels (699 and 146 bytes) assemble, map and execute correctly;
-  known-answer LZ4 blocks decode bit-for-bit, wide copies of 0–1024 bytes
+  known-answer LZ4 blocks decode bit-for-bit, wide copies of 0-1024 bytes
   match, malformed input returns the correct error codes.
 
 
-## [0.16.0] — 2026-07-21
+## [0.16.0] - 2026-07-21
 
-The scalar conversions between vector and general-purpose registers — the
+The scalar conversions between vector and general-purpose registers; the
 last of the amd64 EVEX instruction set.
 
 ### Added
 
 - `asm`: the GPR-interchanging conversions, byte for byte against the Go
   assembler (28 ground-truth cases including memory sources and extended
-  GPRs): vector to GPR — the signed and truncated VCVT{,T}S{D,S}2SI{,Q}
+  GPRs): vector to GPR; the signed and truncated VCVT{,T}S{D,S}2SI{,Q}
   in both VEX and EVEX, and the unsigned VCVT{,T}S{D,S}2USI{L,Q}
-  (EVEX only); GPR to vector — VCVTSI2SD{L,Q}/VCVTSI2SS{L,Q} (VEX and
+  (EVEX only); GPR to vector; VCVTSI2SD{L,Q}/VCVTSI2SS{L,Q} (VEX and
   EVEX) and VCVTUSI2SD{L,Q}/VCVTUSI2SS{L,Q} (EVEX only), whose preserved
   vector source sits in vvvv (three Plan 9 operands).
 
-## [0.15.0] — 2026-07-20
+## [0.15.0] - 2026-07-20
 
-The last of the EVEX conversions and narrowing/extending moves — the EVEX
+The last of the EVEX conversions and narrowing/extending moves; the EVEX
 instruction set is now complete save for the GPR-interchanging forms.
 
 ### Added
 
-- `asm`: the unsigned and truncating conversions — VCVTPD2PS (and the X/Y
+- `asm`: the unsigned and truncating conversions; VCVTPD2PS (and the X/Y
   spellings, whose length the spelling fixes), VCVTPD2UDQ (X/Y),
   VCVTTPD2UDQ (X/Y), VCVTTPD2UQQ, VCVTPS2UDQ, VCVTTPS2UDQ, VCVTPS2UQQ,
   VCVTTPS2UQQ, VCVTTPD2QQ, VCVTTPS2QQ, VCVTUQQ2PD, VCVTUQQ2PS (X/Y) and
@@ -625,20 +780,20 @@ instruction set is now complete save for the GPR-interchanging forms.
   D2M/Q2M), whose K register is a genuine operand rather than a mask and
   which therefore take no masking suffixes.
 
-## [0.14.0] — 2026-07-19
+## [0.14.0] - 2026-07-19
 
 The floating-point helper and conversion tail of the AVX-512 set, plus
-gather and scatter with VSIB addressing — every encoding verified byte for
+gather and scatter with VSIB addressing; every encoding verified byte for
 byte against the Go assembler.
 
 ### Added
 
-- `asm`: the floating-point helpers — reciprocals and reciprocal square
+- `asm`: the floating-point helpers; reciprocals and reciprocal square
   roots (VRCP14/VRSQRT14 PD/PS/SD/SS), exponents and mantissas (VGETEXP*,
   VGETMANT*), scaling by powers of two (VSCALEF*), rounding (VRNDSCALE*),
   reduction (VREDUCE*), immediate fixup (VFIXUPIMM*) and range selection
   (VRANGE*), and floating-point class tests (VFPCLASSPD/PS X/Y/Z and
-  VFPCLASSSD/SS — a new immediate form whose reg field carries the opmask
+  VFPCLASSSD/SS; a new immediate form whose reg field carries the opmask
   destination).
 - `asm`: **gather and scatter with VSIB addressing.**  The gathers take
   both Go spellings: the VEX form with a vector mask register (OP mask,
@@ -647,14 +802,14 @@ byte against the Go assembler.
   data register (a ZMM index with an YMM destination encodes L'L = 10, as
   the Go assembler emits).  The scatters (VSCATTER*/VPSCATTER*) are EVEX
   only (OP src, K, vsib).  All eight gather and eight scatter widths.
-- `asm`: the remaining conversions — VCVTQQ2PS (the 512-bit source sets
+- `asm`: the remaining conversions; VCVTQQ2PS (the 512-bit source sets
   the length), VCVTPD2QQ/UQQ, VCVTPS2QQ, VCVTUDQ2PD/PS, the half-precision
   VCVTPH2PS and VCVTPS2PH (the extract layout with an immediate).
 
-## [0.13.0] — 2026-07-18
+## [0.13.0] - 2026-07-18
 
 The wider AVX-512 set: ternary logic, permutes, compares, expand/compress,
-the opmask instructions and the EVEX rounding/SAE/broadcast suffixes — every
+the opmask instructions and the EVEX rounding/SAE/broadcast suffixes; every
 encoding verified byte for byte against the Go assembler.
 
 ### Added
@@ -662,7 +817,7 @@ encoding verified byte for byte against the Go assembler.
 - `asm`: the wider EVEX/AVX-512 set, across roughly sixty new ground-truth
   cases: ternary logic (VPTERNLOGD/Q), the lane shuffles/inserts/extracts
   (VSHUF{F,I}{32,64}X{2,4}, the VINSERT*/VEXTRACT* {F,I}{32,64}X{2,4,8}
-  family, VPALIGNR), compares with an opmask destination (VCMPPD/PS/SD/SS —
+  family, VPALIGNR), compares with an opmask destination (VCMPPD/PS/SD/SS;
   a new NDS-plus-immediate form with the K register in the reg field), the
   permutes (VPERMB/W, VPERMI2/T2 D/Q/PD), the wider integer families
   (VPMADDWD/UBSW, VPMULHUW, VPACKSSWB/USWB/SSDW/USDW, VPABS B/W/D/Q, the
@@ -676,15 +831,15 @@ encoding verified byte for byte against the Go assembler.
   (VMOVSLDUP/VMOVSHDUP), the conversions (VCVTPS2DQ, VCVTTPS2DQ) and the
   remaining extending and narrowing moves (VPMOVSXBW, VPMOVZXBW, VPMOVWB,
   VPMOVQB).
-- `asm`: the EVEX mnemonic suffixes the Go assembler accepts — the rounding
+- `asm`: the EVEX mnemonic suffixes the Go assembler accepts; the rounding
   modes `.RN_SAE`, `.RD_SAE`, `.RU_SAE`, `.RZ_SAE` (the EVEX b bit with the
   rounding control in L'L), suppress-all-exceptions `.SAE`, and memory
   broadcast `.BCST` (the b bit, the vector length preserved, disp8×N scaled
-  by the element size) — each combinable with the `.Z` zeroing suffix,
+  by the element size); each combinable with the `.Z` zeroing suffix,
   validated against the Go assembler's bytes, and rejected on instructions
   that do not support them.
 
-## [0.12.0] — 2026-07-17
+## [0.12.0] - 2026-07-17
 
 GOOBJ emission: gasm-assembled functions drop into a `go build` without the
 Go assembler.
@@ -692,7 +847,7 @@ Go assembler.
 ### Added
 
 - `asm`: **GOOBJ object output.**  `gasm asm --format goobj -p <pkgpath>`
-  writes the Go toolchain's own object format — the one `cmd/link` consumes
+  writes the Go toolchain's own object format; the one `cmd/link` consumes
   directly: the functions as non-package symbols qualified with the package
   path (exactly as `cmd/asm` records assembly symbols), the `GLOBL` data,
   one serialized `FuncInfo` per function (argument/frame sizes, the asm
@@ -701,8 +856,8 @@ Go assembler.
   real stack deltas: the assembler now tracks every stack-adjustment
   boundary through the prologue (`PUSHQ BP`, `SUBQ $frame, SP`) and each
   `RET`'s epilogue, so frame-pointer functions unwind correctly.  The
-  object preamble — the version-and-experiment header the linker compares
+  object preamble; the version-and-experiment header the linker compares
-  verbatim — is captured from the installed `go tool asm`, so the output is
+  verbatim; is captured from the installed `go tool asm`, so the output is
   always consistent with the toolchain that links it.
 - `asm`: relocations against file-local `GLOBL` symbols become `R_PCREL`
   entries in the GOOBJ output, with the instruction's displacement field
@@ -715,7 +870,7 @@ Go assembler.
   pattern, instead of being rejected as non-integer.
 
 
-## [0.11.0] — 2026-07-16
+## [0.11.0] - 2026-07-16
 
 Linkable object output: external symbols and relocatable ELF / Mach-O
 objects.
@@ -734,7 +889,7 @@ objects.
   external symbol; the Mach-O output is verified structurally with
   `debug/macho`.
 - `asm`: **external symbol references.**  A reference to a symbol no
-  `GLOBL` in the file defines no longer aborts assembly — it is recorded
+  `GLOBL` in the file defines no longer aborts assembly; it is recorded
   as an external relocation (`Image.Externals`, `FuncLayout.Relocs`) and
   becomes an undefined global symbol in the object output.  The raw image
   s (`--format raw`, the default) still reports them: only an object
@@ -746,7 +901,7 @@ objects.
   writes; without `--format` the behaviour is unchanged (the concatenated
   image).
 
-## [0.10.0] — 2026-07-15
+## [0.10.0] - 2026-07-15
 
 The EVEX floating-point and conversion set: the packed-double arithmetic,
 the scalar SD/SS forms, VMOVDDUP and the width-changing conversions, each
@@ -754,23 +909,23 @@ verified byte for byte against the Go assembler.
 
 ### Added
 
-- `asm`: the rest of the common EVEX/VEX floating-point set — packed double
+- `asm`: the rest of the common EVEX/VEX floating-point set; packed double
   arithmetic (VSUBPD, VDIVPD, VMINPD, VMAXPD, VUNPCKLPD and the EVEX form of
   VUNPCKHPD), the scalar double and single operations (VSUBSD, VDIVSD,
   VMINSD, VMAXSD and the full VADDSS/VSUBSS/VMULSS/VDIVSS/VMINSS/VMAXSS
-  family in both VEX and EVEX — the EVEX scalar forms exist for masked and
+  family in both VEX and EVEX; the EVEX scalar forms exist for masked and
   zeroing use), and VMOVDDUP (lane duplication, VEX and EVEX).
-- `asm`: the width-changing conversions — VCVTDQ2PS and VCVTPS2PD (VEX and
+- `asm`: the width-changing conversions; VCVTDQ2PS and VCVTPS2PD (VEX and
   EVEX; the destination sets the length for PS→PD), the EVEX form of
   VCVTDQ2PD, and the packed-double → dword family: VCVTPD2DQ/VCVTTPD2DQ
   (EVEX-512 only, a ZMM source and an XMM destination) and their X/Y
   spellings (VCVTPD2DQX/Y, VCVTTPD2DQX/Y), whose length follows the wider
-  source — a new operand form, since the destination is always XMM while
+  source; a new operand form, since the destination is always XMM while
   VEX.L / EVEX.L'L ride with the source (fixed by the spelling even for a
   memory source).
-- `asm`: masking and zeroing on every new form — the scalar SD/SS
+- `asm`: masking and zeroing on every new form; the scalar SD/SS
   arithmetic, the unpacks, VMOVDDUP and the conversions all accept the
-  explicit K1–K7 operand and the `.Z` suffix the way Go writes them.
+  explicit K1-K7 operand and the `.Z` suffix the way Go writes them.
 
 ### Changed
 
@@ -781,35 +936,35 @@ verified byte for byte against the Go assembler.
   shares the convention).
 
 
-## [0.9.0] — 2026-07-14
+## [0.9.0] - 2026-07-14
 
 AVX-512 masking and a wider EVEX integer set.
 
 ### Added
 
-- `asm`: **EVEX masking** the way Go writes it — an explicit `K1`–`K7`
+- `asm`: **EVEX masking** the way Go writes it; an explicit `K1`-`K7`
   operand placed among the operands (merging mask), and a `.Z` mnemonic
   suffix for zeroing (`VPADDD.Z Z1, Z2, K2, Z3`).  Supported across the NDS,
   reg/rm, immediate-shift, align, extract, convert and move forms, including
   masked comparisons with a K destination (`VPCMPEQD Z0, Z3, K2, K1`).  K0 is
   rejected as an explicit mask, and `.Z` without a mask is an error, matching
   the Go assembler.
-- `asm`: the common AVX-512 F/BW integer set — VPADDB/W, VPSUBB/W, VPANDD/Q,
+- `asm`: the common AVX-512 F/BW integer set; VPADDB/W, VPSUBB/W, VPANDD/Q,
   VPANDND/Q, VPMULLW, VPAVGB/W, the signed/unsigned min/max family for
   B/W/D/Q elements, the variable shifts VPSLLVD/Q, VPSRLVD/Q, VPSRAVD/Q, the
   EVEX forms of VPSHUFD/VPSHUFB, and the VMOVDQU8/VMOVDQU16 move aliases.
-  Register indices 16–31 encode correctly (the mod=11 quirk carries rm[4]
+  Register indices 16-31 encode correctly (the mod=11 quirk carries rm[4]
   in X̄).  All verified byte for byte against the Go assembler.
 - `lint`: masked EVEX forms (`.Z` suffix, K operands) are recognised by
   `unknown-instruction` and exempted from `operand-count`.
 
 ### Fixed
 
-- `asm`: EVEX register–register operands with indices 16–31 encoded rm[4]
+- `asm`: EVEX register-register operands with indices 16-31 encoded rm[4]
   into B̄ instead of X̄ (the EVEX mod=11 extension quirk), producing wrong
   prefix bytes for X16+/Y16+ r/m operands.
 
-## [0.8.0] — 2026-07-13
+## [0.8.0] - 2026-07-13
 
 Standard CLI ergonomics.
 
@@ -825,20 +980,20 @@ Standard CLI ergonomics.
 - The version is primarily available as the standard `gasm --version` / `-V`
   flag; the `gasm version` spelling remains as an alias.
 
-## [0.7.0] — 2026-07-12
+## [0.7.0] - 2026-07-12
 
 The formatter behaves like `go fmt` and canonicalises block separation.
 
 ### Added
 
-- `gasm fmt` now works like `go fmt`: with no arguments — or with a directory
+- `gasm fmt` now works like `go fmt`: with no arguments; or with a directory
-  argument — it reformats every `.s` file below it in place and lists the
+  argument; it reformats every `.s` file below it in place and lists the
   changed files, skipping `.` and `_` directories (`.git`, `_refs`, …).
   Explicit file arguments keep the `-w` / standard-output behaviour.
 
 ### Changed
 
-- `s`: canonical blank-line layout — a new block (a label, `TEXT` or
+- `s`: canonical blank-line layout; a new block (a label, `TEXT` or
   `GLOBL`) is preceded by exactly one blank line, neither more nor less.
   Comments leading a block stay with it (the blank line goes before them),
   stacked labels share their block, the function's first label keeps hugging
@@ -847,7 +1002,7 @@ The formatter behaves like `go fmt` and canonicalises block separation.
   kernels were reformatted with this release and remain byte-identical when
   assembled.
 
-## [0.6.0] — 2026-07-11
+## [0.6.0] - 2026-07-11
 
 Calibrated to the Go ABI: `register-clobber` stops reporting legal code, and
 the encoder learns the legacy SSE moves.
@@ -856,13 +1011,13 @@ the encoder learns the legacy SSE moves.
 
 - `lint`: **`register-clobber` is now calibrated to the Go ABI**
   (`cmd/compile/abi-internal.md`), not the platform ABI.  Go's stack-based
-  ABI0 has no System V style callee-saved registers — amd64 `BX`, `R12`–`R15`
+  ABI0 has no System V style callee-saved registers; amd64 `BX`, `R12`-`R15`
   and the arm64/riscv64/loong64 scratch sets are caller-saved or permanent
   scratch, and hand-written kernels may clobber them freely.  The rule now
   audits only the registers Go fixes across calls: the frame pointer and the
   goroutine pointer (amd64 `BP`/`R14`, arm64 `R18`/`R28`/`R29`, riscv64
   `X27`, loong64 `R22`), and the goroutine pointer is reported only when the
-  function can reach the runtime (is not `NOSPLIT` or makes a call) — the
+  function can reach the runtime (is not `NOSPLIT` or makes a call); the
   ABI0 transition restores it on those paths, and NOSPLIT call-free leaves
   may use it, exactly as the runtime's own assembly does.  Both go-flac
   kernels now lint with zero diagnostics.
@@ -879,21 +1034,21 @@ the encoder learns the legacy SSE moves.
 
 ### Added
 
-- `asm`: the legacy (non-VEX) SSE moves — `MOVOU`/`MOVO` (the Plan 9 names
+- `asm`: the legacy (non-VEX) SSE moves; `MOVOU`/`MOVO` (the Plan 9 names
   for MOVDQU/MOVDQA), `MOVUPS`/`MOVAPS`/`MOVUPD`/`MOVAPD` and the scalar
-  `MOVSD`/`MOVSS` — and `VMOVDQU64` in the EVEX set.  All verified byte for
+  `MOVSD`/`MOVSS`; and `VMOVDQU64` in the EVEX set.  All verified byte for
   byte against the Go assembler.
 
-## [0.5.0] — 2026-07-10
+## [0.5.0] - 2026-07-10
 
 EVEX / AVX-512: the go-flac AVX-512 kernel now assembles, byte-identically to
 the Go toolchain, completing the production-kernel coverage.
 
 ### Added
 
-- `asm`: **EVEX (AVX-512) encoding** — the four-byte EVEX prefix with the
+- `asm`: **EVEX (AVX-512) encoding**; the four-byte EVEX prefix with the
-  5-bit register fields (Z0–Z31, X/Y 16–31, with the reg-r/m X̄ quirk and
+  5-bit register fields (Z0-Z31, X/Y 16-31, with the reg-r/m X̄ quirk and
-  V'̄ shared between vvvv and the SIB index), opmask registers (K0–K7) as
+  V'̄ shared between vvvv and the SIB index), opmask registers (K0-K7) as
   operands and as mask destinations, and the compressed disp8×N displacement
   (the multiplier follows the memory operand's size, as the Go assembler's
   opcode tables prescribe).  Covers every AVX-512 instruction the go-flac
@@ -903,20 +1058,20 @@ the Go toolchain, completing the production-kernel coverage.
   extracts VEXTRACTI64X4/VEXTRACTF64X4, VFMADD231PD, VADDPD, VMULPD, the
   broadcasts VPBROADCASTD/Q (GPR and memory sources take different opcodes)
   and the mask moves KMOVW/KTESTW.  Masking/zeroing suffixes are out of scope
-  — the kernels use neither.
+ ; the kernels use neither.
 - `asm`: `AssembleFile` now accepts file-defined global (`non-<>`) symbols
   too; a reference is external only when no `GLOBL` in the file defines it.
 
 ### Fixed
 
-- `asm`: registers X16–Y31 force the EVEX encoding of dual-form mnemonics;
+- `asm`: registers X16-Y31 force the EVEX encoding of dual-form mnemonics;
   previously a `VPBROADCASTD AX, Y30` fell into the VEX encoder, which cannot
   represent indices above 15 and silently truncated them.
-- `asm`: the VEX encoder now rejects vector register indices 16–31 instead of
+- `asm`: the VEX encoder now rejects vector register indices 16-31 instead of
   encoding a truncated (wrong) register.
 
 
-## [0.4.0] — 2026-07-09
+## [0.4.0] - 2026-07-09
 
 The standalone assembler reaches the whole go-flac AVX2 kernel: static
 symbols assemble, and all 17 kernel functions now match the Go toolchain's
@@ -924,10 +1079,10 @@ machine code byte for byte.
 
 ### Added
 
-- `asm`: **file-level assembly** — `AssembleFile` turns a parsed file into an
+- `asm`: **file-level assembly**; `AssembleFile` turns a parsed file into an
   `Image`: the function bodies in source order followed by a data section
   built from the file's `GLOBL`/`DATA` directives (each symbol 16-aligned).
-- `asm`: **static-symbol (`SB`) operands** — `mask<>(SB)` references encode as
+- `asm`: **static-symbol (`SB`) operands**; `mask<>(SB)` references encode as
   RIP-relative loads with a patched disp32, resolved against the image layout
   so the output is self-consistent and position-independent.  External
   (non-file-local) symbols are rejected with a clear error: they need
@@ -936,7 +1091,7 @@ machine code byte for byte.
   and writes the whole image (code + data) with `-o`.
 
 
-## [0.3.0] — 2026-07-08
+## [0.3.0] - 2026-07-08
 
 The assembler reaches byte-identical parity with the Go toolchain on the
 production go-flac AVX2 kernels: every one of the 15 kernel functions that
@@ -946,18 +1101,18 @@ support).
 
 ### Added
 
-- `asm`: the scalar instruction families the kernels use — `CMOVcc` and
+- `asm`: the scalar instruction families the kernels use; `CMOVcc` and
   `SETcc` (conditions spelled exactly like the jumps), `LZCNT`/`TZCNT`
   (legacy `F3 0F BD/BC`), the sign/zero-extending moves (`MOVBLZX`, `MOVBQZX`,
   `MOVWLZX`, `MOVWQZX`, `MOVWLSX`, `MOVLQSX`), `CVTSL2SD`/`CVTSQ2SD` (the
   legacy SSE encoding, as the Go assembler emits it), the traditional
   three-operand `IMUL3{W,L,Q}`, and the variable-count vector shifts
-  (`VPSRLQ X0, Y8, Y8` — the count in an XMM register or memory takes the
+  (`VPSRLQ X0, Y8, Y8`; the count in an XMM register or memory takes the
   ordinary NDS form).
-- `asm`: **jump relaxation** — jumps start in the short (rel8) form and
+- `asm`: **jump relaxation**; jumps start in the short (rel8) form and
   expand to rel32 when the settled displacement does not fit, iterating the
   layout to a fixed point (CALL is always rel32).
-- `asm`: **jump-to-jump folding** — a conditional jump to a label whose only
+- `asm`: **jump-to-jump folding**; a conditional jump to a label whose only
   instruction is an unconditional jump is redirected to the ultimate
   target, replicating the Go toolchain's linker, which chases such chains
   before it encodes branches.
@@ -969,12 +1124,12 @@ support).
 - `asm`: `CMP` with a register or memory operand computed **second − first**
   instead of first − second, silently inverting every condition that followed
   (`CMPQ SI, R10; JGE` tested R10 ≥ SI).  The encoding now always records
-  first − second — `CMP r/m, r` with the first operand in r/m, `CMP r, r/m`
+  first − second; `CMP r/m, r` with the first operand in r/m, `CMP r, r/m`
-  with the first operand in reg — and is byte-identical to the Go assembler.
+  with the first operand in reg; and is byte-identical to the Go assembler.
 - `asm`: register-to-register `MOV` now uses the `r/m ← r` opcode (reg =
   source), the Go assembler's choice; the output is byte-identical.
 
-## [0.2.0] — 2026-07-07
+## [0.2.0] - 2026-07-07
 
 The Phase 2 assembler grows the SIMD set: shuffles, extract/insert, permute
 and the moves, on top of the Phase 1 VEX forms.
@@ -987,10 +1142,10 @@ and the moves, on top of the Phase 1 VEX forms.
   - the immediate shuffle (`VPSHUFD`, `VPERMQ`),
   - the three-operand-plus-immediate form (`VSHUFPD`, `VPERM2I128`,
     `VINSERTI128`),
-  - the lane extract (`VEXTRACTI128`, `VEXTRACTF128` — the YMM source occupies
+  - the lane extract (`VEXTRACTI128`, `VEXTRACTF128`; the YMM source occupies
     the ModRM.reg field, the XMM/memory destination the r/m field),
   - the direction-sensitive moves (`VMOVDQU`, `VMOVUPD`, `VMOVD`, `VMOVQ`,
-    `VMOVSD` — each direction picks its own opcode and VEX.W; a vector→vector
+    `VMOVSD`; each direction picks its own opcode and VEX.W; a vector→vector
     move uses the store-form layout, matching the Go assembler),
   - the no-operand `VZEROUPPER`, and `VPERMD` in the NDS form,
   - the floating-point and FMA set (`VADDPD`, `VMULPD`, `VXORPD`,
@@ -999,21 +1154,21 @@ and the moves, on top of the Phase 1 VEX forms.
   the encoder now covers every integer, shuffle and FP instruction the
   go-flac AVX2 kernels use.
 - `asm`: `CMP` accepts the immediate in the second operand position
-  (`CMPL CX, $31`) — the spelling the Go assembler accepts — encoding it
+  (`CMPL CX, $31`), the spelling the Go assembler accepts, encoding it
   identically to the immediate-first form.
 
 ### Fixed
 
 - `asm`: an unused VEX.vvvv field is now stored as `1111` (v̄vvv = 1111), as
-  the hardware requires — the previous value (`0000`) made the two-operand
+  the hardware requires; the previous value (`0000`) made the two-operand
   reg/rm forms (VPMOVSXWD, VPBROADCASTD, VMOVMSKPS, …) raise #UD on real CPUs
   and differ from the Go assembler's bytes.  The round-trip decoder ignores
   the field on these instructions, which is why the byte-for-byte Go
   comparison (added this release) is now part of the test suite.
 
-## [0.1.0] — 2026-07-06
+## [0.1.0] - 2026-07-06
 
-Initial release — the Phase 1 foundation.
+Initial release; the Phase 1 foundation.
 
 ### Added
 
@@ -1026,11 +1181,11 @@ Initial release — the Phase 1 foundation.
 - `arch`: register files and **complete** instruction tables for amd64,
   arm64, riscv64 and loong64, with the middle-dot symbol separator and static
   (`<>`) symbols.  Instruction names are generated from the Go toolchain's own
-  assembler source (`just gen`) — the `anames` opcode lists plus the common
+  assembler source (`just gen`); the `anames` opcode lists plus the common
   opcodes and the per-architecture front-end aliases (arm64 `B`/`BL`, the
   `.P`/`.W` addressing suffixes, loong64 `JAL`, the x86 conditional-jump
-  spellings) — so every mnemonic the real assembler accepts is recognised.
+  spellings); so every mnemonic the real assembler accepts is recognised.
-- `lint`: conservative rules — `unknown-instruction`, `operand-count`,
+- `lint`: conservative rules; `unknown-instruction`, `operand-count`,
   `undefined-label`, `duplicate-label`, `missing-ret`,
   `missing-textflag-include`, `abi-argsize` and `unreachable-code`.  Macro
   invocations are recognised (in-file `#define` names and underscore
@@ -1052,9 +1207,9 @@ Initial release — the Phase 1 foundation.
 - `lsp`: a Language Server Protocol server over stdio providing completion,
   hover documentation, document symbols, publish-diagnostics and semantic-token
   highlighting.
-- `asm`: a standalone amd64 (x86-64) assembler — an instruction encoder (REX/
+- `asm`: a standalone amd64 (x86-64) assembler; an instruction encoder (REX/
   ModR-M/SIB/displacement/immediate plus the scalar instruction set, and VEX/
-  AVX2 SIMD across three operand forms — NDS, reg/rm and immediate-shift —
+  AVX2 SIMD across the three operand forms NDS, reg/rm and immediate-shift,
   covering the bulk of the integer SIMD set) validated by round-trip decoding
   against `golang.org/x/arch`, and an assembler that drives the parser's AST
   into the encoder with local-label resolution and `FP`/`SP` frame mapping

CONTRIBUTING.md

@@ -1,107 +1,127 @@
-# Contributing to gasm-devkit
+# Contributing
 
-Thanks for contributing to gasm-devkit.
+Contributions to **gasm-devkit** are governed by the Contributor terms
+below; submitting one means you accept them.
+
+## Contributor terms
+
+1. This project belongs to its owner alone. The owner decides what is
+   accepted, in what form and when; the decision is final and needs no
+   justification.
+2. By submitting a contribution you assign to Petr Balvín
+   <opensource@petrbalvin.org> all present and future copyright and
+   related rights in it, worldwide, for the full term of the rights,
+   with the right to relicense and sublicense without restriction,
+   including under proprietary terms.
+3. Where that assignment is not effective, it counts as a perpetual,
+   irrevocable, royalty-free licence with the same scope.
+4. To the fullest extent permitted by law, you waive any right of
+   attribution and integrity in the contribution. The project names no
+   contributors and keeps no credits list.
+5. By submitting you represent that the work is yours and that you
+   hold the rights to assign it as above.
 
 ## Development setup
 
-Requirements: Go 1.27 or later, the [just](https://github.com/casey/just)
+Requirements: Go 1.27.1, the exact version the `go` directive in `go.mod`
-command runner, and a Linux host on amd64, arm64, riscv64 or loong64.
+declares, and [just](https://github.com/casey/just) for the recipes.
 
 ```sh
 git clone https://sourcedock.dev/petrbalvin/gasm-devkit.git
 cd gasm-devkit
-just install        # download module dependencies
+just build
-just build          # go vet + gofmt check
+just gates
-just test           # full suite, race detector, 80 % coverage gate
 ```
 
 ## Workflow
 
-1. Branch from `development`; never commit directly to `main` (`main` is
+1. Branch from `development`. Never commit directly to `main`, which is release-only.
-   release-only: merge from `development`, then tag).
+2. Commit in [Conventional Commits](https://www.conventionalcommits.org/) form:
-2. Commit with [Conventional Commits](https://www.conventionalcommits.org/):
+   `type(scope): description`, subject line only, imperative mood, lowercase after the
-   `type(scope): description`: subject line only, imperative mood,
+   colon, no trailing full stop. Allowed types: `feat`, `fix`, `docs`, `style`,
-   lowercase after the colon, no trailing dot.  Allowed types: `feat`,
+   `refactor`, `perf`, `test`, `chore`, `ci`, `build`, `revert`.
-   `fix`, `docs`, `style`, `refactor`, `perf`, `test`, `chore`, `ci`,
+3. One logical change per commit. A refactor, a behaviour change and a formatting pass
-   `build`, `revert`.  The only line after the subject is the trailer:
+   are three commits, never one.
-   `Assisted-by: <model-name>`.  No `Co-Authored-By`, no `Signed-off-by`,
+4. Record every user-visible change in `CHANGELOG.md` under `## [development]`.
-   no other trailers.
+5. Add or update tests. Coverage stays at 80 percent or more; it is a hard gate.
-3. Record every user-visible change in `CHANGELOG.md` under
+6. Update the documentation when the public API, the configuration or the behaviour
-   `## [development]` (categories: Added, Changed, Fixed, Removed,
+   changes.
-   Security).
+7. Open a pull request against `development`.
-4. Add or update tests; coverage must stay **at or above 80 %** (hard
-   gate, enforced by CI).
-5. Update the documentation when behaviour, flags or the public surface
-   change.
-6. Open a pull request against `development`.
 
-Releases are cut by merging `development` into `main` and tagging `vX.Y.Z`;
+Releases are cut by merging `development` into `main` and tagging `vX.Y.Z`. The release
-CI builds and publishes the binaries for all four architectures.
+workflow builds the assets and publishes the release and its notes.
 
 ## Code style
 
-`gofmt` and `go vet` via `just fmt` / `just build`; both must pass with
+`gofmt` and `go vet` run through `just fmt` and `just vet`, with zero diff and zero
-zero output; `go fix -diff ./...` must report nothing on touched packages.
+warnings tolerated. `just gates` is the definition of done in one command, and the recipe
+file names what it contains. Errors are checked explicitly, wrapped as
+`fmt.Errorf("context: %w", err)`, and nothing panics outside `main`. The `golang`
+skill holds the rules the project follows; the recipe file holds the commands.
 
-- Standard library only in production code; `golang.org/x/arch` is used
+- `golang.org/x/arch` is the one module dependency, and it is linked into the binary:
-  in tests only (round-trip decoding) and is never linked into the `gasm`
+  `gasm dis` and the debugger's listings decode through it. Everything else is the
-  binary.
+  standard library.
-- No cgo, no C, no external toolchains at runtime.
+- No cgo, no C, no external toolchain at runtime.
-- Explicit `if err != nil`; errors wrapped with
+- The parser, lexer and formatter are hand-written; the `arch` instruction tables are
-  `fmt.Errorf("context: %w", err)`; no panics outside `main`.
+  generated only by `_gen/gen.go` (`just gen`) and never edited by hand.
-- The parser, lexer and formatter are hand-written; the `arch` instruction
+- Assembly committed to the repository goes through `gasm fmt` and `gasm lint`, so a
-  tables are generated only via `_gen/gen.go` (`just gen`), never edited.
+  `.s` file that `gasm fmt -l .` lists is unfinished.
 
-## Running a single test
+New source files open with the project's two-line licence header, whose SPDX
+identifier matches `LICENSE`. Configuration files, workflows and dotfiles do not carry
+it.
 
-```sh
+## AI contribution policy
-go test -run TestVexGroundTruth ./asm/
+
-go test -run TestGroundTruthBasic ./verify/
+AI tools are welcome as productivity aids and are a normal part of modern software
-go test -run TestGOObjectLinkAndRun ./asm/
+development. What matters is that the contribution stays understandable, reviewable and
-go test -run TestFuzzWideCopy ./verify/
+genuinely useful.
+
+- **Disclose the assistance.** If AI helped draft any part of a commit, issue, pull
+  request or review, say so.
+- **Commit messages carry exactly one trailer**, as a git trailer on the line after a
+  blank line that closes the subject:
+
+  ```
+  Assisted-by: MODEL
   ```
 
-The interactive debugger (`gasm debug`) requires a compiled binary on
+  Name the model that did the work, spelled the way its maker spells it, for example
-`$PATH`; `go run` does not work for the traced child process.  Install
+  `GLM 5.3`, `DeepSeek V4.1 Flash` or `Qwen 3.8 Flash`. No `Co-Authored-By`, no `Signed-off-by`,
-first with `just install-bin`.
+  no other trailers, and no prose: the trailer is the disclosure.
+- **Issues and pull requests** attribute the assistance in a comment, for example
+  `_Assisted-by: GLM 5.3_`. It does not belong in the pull request description.
+- **Take responsibility.** You are accountable for the accuracy, completeness and
+  intent of everything you submit, whether or not AI produced it.
+- **Review before marking ready.** Read the diff carefully, run it locally, and add the
+  tests it needs. Do not mark a pull request ready until you can defend every change in
+  it.
+- **Quality over quantity.** Contributions that look like un-reviewed output, or whose
+  author cannot engage substantively during review, may be closed.
+- **Preferred models.** Prefer open-weight models with transparent training data and
+  minimal output filtering.
 
-## CI (Gitea Actions)
+AI assists. It does not replace judgement.
 
-Workflows live in `.gitea/workflows/` and run on self-hosted runners:
+## Continuous integration
+
+Workflows live in `.gitea/workflows/` and run on the project's own runners:
 
 | Workflow | Trigger | What it does |
-|----------|---------|--------------|
+|---|---|---|
-| Test | push / PR to `development` | gofmt check, `go vet`, `go test -race`, 80 % coverage gate |
+| Test | push or pull request to `development` | build, format check, vet, modernisation, the test suite with the coverage floor |
-| Release | tag `v*` | cross-compiles binaries for linux/{amd64,arm64,riscv64,loong64} and publishes the Gitea release |
+| Release | a `v*` tag | the same gates as Test, then the matrix build, the proven version and the release itself; the race detector runs locally in `just gates` before the tag is cut |
 
-The Definition of Done (`just build` + `just test` + `just fmt`) must
+The local equivalent is `just gates`, which is the same set plus the race detector. The
-still pass locally before pushing.
+race detector also has its own workflow, dispatched by hand; it never runs on a push or a
-
+tag, where it would double the time and the memory a shared runner cannot spare.
-## AI Contribution Policy
-
-AI tools are welcome as productivity aids.  What matters is that
-contributions remain understandable, reviewable, and genuinely useful.
-
-- **Disclose AI use.**  If you used AI to draft or generate any part of a
-  commit, issue, pull request, or code review, say so clearly.
-- **Commit messages:** end every commit with exactly one trailer:
-  `Assisted-by: <model-name>` (e.g. `Assisted-by: GLM 5.3`).
-- **Pull requests and issues:** attribute AI assistance in one trailing
-  line, e.g. `_Assisted-by: GLM 5.3_`.  Do not paste it into the PR
-  description as a section.
-- **Take responsibility.**  You remain accountable for the accuracy,
-  completeness, and intent of everything you submit.
-- **Review before marking ready.**  Read AI-generated diffs carefully, run
-  them locally, and add or update tests where appropriate.
-- **Preferred models.**  Prefer open-weight models with transparent
-  training data: **GLM**, **DeepSeek**, and **MiMo**.
 
 ## Reporting bugs
 
-Open an issue at
+Open an issue at `https://sourcedock.dev/petrbalvin/gasm-devkit/issues` with the
-[sourcedock.dev/petrbalvin/gasm-devkit](https://sourcedock.dev/petrbalvin/gasm-devkit/issues)
+version, the operating system and architecture, the exact command, the full output,
-with the version (`gasm --version`), OS and architecture, the exact
+and the expected against the actual behaviour.
-command, the full output, and the expected versus actual behaviour.
 
-**Security issues:** email **opensource@petrbalvin.org** instead of opening
+**Security issues do not go in the issue tracker.** Report them as
-a public issue.
+[SECURITY.md](SECURITY.md) describes, to **opensource@petrbalvin.org**.

README.md

@@ -1,13 +1,63 @@
-# gasm-devkit
+# Plan 9 assembly tooling, inside and outside Go
 
-Developer tooling for **GAsm**, Go's built-in Plan 9 assembler.
+> **Warning: this is an experiment.** gasm-devkit is under active
+> development and is not stable. The version is 0.x.x: commands, flags,
+> output formats and behaviour can change without warning at any time.
+> A 1.0.0 release is light years away. Nothing in this document is a
+> stability promise. For all of that, this is not a paper project: gasm
+> is already in active use and is tested on real assembly work.
 
-Go ships an assembler but no tooling for it: there is no syntax highlighting,
+**GAsm** is Go's Plan 9 assembler, and Go ships it without tooling:
-no autocomplete, no linter, no static analyser, no formatter, no standalone
+there is no formatter, no linter, no static analyser, no standalone
-assembler and no debugger for `.s` files.  Developers write assembly blind,
+assembler and no debugger for `.s` files. Developers write assembly
-validate it by benchmark, and debug it by print statement.  gasm-devkit is the
+blind, validate it by benchmark, and debug it by print statement.
-missing toolkit: a single, self-contained binary, `gasm`, that brings proper
+gasm-devkit is the missing toolkit: a single, self-contained binary,
-developer tooling to Plan 9 assembly on amd64, arm64, riscv64 and loong64.
+`gasm`, that serves both purposes.
+
+- **Help develop Plan 9 assembly.** Formatting, linting, disassembly,
+  dynamic verification, a source-level debugger and a language server,
+  for `.s` files in Go programs.
+- **Use Plan 9 assembly outside the Go toolchain.** `gasm asm` encodes
+  on its own, with no Go installation in the loop, and writes raw
+  images, linkable ELF objects with DWARF5 debug sections, or the Go
+  toolchain's own GOOBJ format, which `go build` consumes in place of
+  the toolchain's output.
+
+## Why Plan 9 assembly
+
+Plan 9 assembly is the quiet triumph of the field. One syntax across
+every architecture Go builds for: the same source-first operand order,
+the same four pseudo-registers, the same frame convention, whether the
+target is x86, ARM, RISC-V or LoongArch. Learn it once and you can
+read a kernel on any of them.
+
+Compare the alternatives. Intel syntax and AT&T syntax disagree on the
+one question every instruction answers, which operand is the source
+and which is the destination, so half the world writes it one way,
+half the other, and every assembly programmer carries both in their
+head forever. GNU as settles the argument with directives that switch
+dialects mid-file (`.intel_syntax noprefix`), a percent sign on every
+register and a dollar on every immediate: punctuation that carries
+nothing the operand order did not already say. And the x86 family
+fragments again underneath: NASM is not MASM is not GAS, each with its
+own directive zoo and macro language, so every project picks a dialect
+and every reader learns a different one by accident.
+
+Plan 9 assembly has none of it. Registers are bare names. Memory is
+one notation, `offset(base)`, extended by an index and a scale when
+the instruction needs it. Arguments arrive named and offset-checked:
+`x+0(FP)` is the argument x, on every architecture, and `go vet`
+polices the offsets against the Go prototype.
+
+```text
+AT&T (GNU as):   movq %rax, -16(%rbp)
+Plan 9 (Go):     MOVQ AX, total-16(SP)
+```
+
+The same lines, but only one of them tells you what the number is for.
+The syntax is uppercase, regular and boring, which is the highest
+compliment a language for machine code can earn. gasm-devkit exists
+to give that syntax the tooling it deserves.
 
 ## Features
 
@@ -16,7 +66,8 @@ developer tooling to Plan 9 assembly on amd64, arm64, riscv64 and loong64.
   directly.
 - **Formatter.**  `gasm fmt` canonicalises indentation, operand spacing,
   per-function mnemonic alignment and blank-line layout: `gofmt` for assembly,
-  operating recursively on directories the way `go fmt` does.
+  operating recursively on directories the way `go fmt` does.  `-l` lists
+  files whose formatting differs and `-d` prints a unified diff.
 - **Linter.**  `gasm lint` runs 18 conservative static checks, among them
   `undefined-label`, `abi-argsize` (declared frame vs the `// func` signature),
   `register-clobber` (Go ABI register liveness over the control-flow graph),
@@ -24,7 +75,11 @@ developer tooling to Plan 9 assembly on amd64, arm64, riscv64 and loong64.
 - **Standalone assembler.**  `gasm asm` encodes all four architectures without
   the Go toolchain and writes raw images, linkable ELF objects (with DWARF5
   debug sections) or the Go toolchain's own GOOBJ format, which `go build`
-  consumes in place of the toolchain's output.
+  consumes in place of the toolchain's output.  Framed functions get the
+  stack-split guard and the morestack block, byte-identical to the
+  toolchain's, so split functions link too.
+- **Disassembler.**  `gasm dis` lists a `.s` file's functions at their real
+  offsets after assembling, or disassembles raw bytes from a file or stdin.
 - **Dynamic verification.**  `gasm verify` JIT-loads assembled functions into
   executable memory: smoke calls, ABI checks (sentinel registers, red-zone
   canary), differential fuzzing against the `go tool asm` build, and
@@ -36,17 +91,17 @@ developer tooling to Plan 9 assembly on amd64, arm64, riscv64 and loong64.
   push and pull diagnostics, semantic-token highlighting, go-to-definition,
   find references, rename, formatting, inlay hints, code actions, signature
   help, document highlights, workspace symbol search, #include document
-  links and folding ranges over stdio.
+  links and folding ranges over stdio; definition, references and rename
+  work across every open document.
 - **Comparators and audits.**  `gasm diff` compares the machine code of two
   assembly files byte-for-byte, `gasm profile` shows basic-block structure,
   `gasm audit-instructions` diffs the encoder against the installed toolchain,
   and `gasm scaffold` generates a differential test skeleton for a kernel.
-- **Complete instruction coverage.**  The instruction tables are generated
-  from the Go toolchain's own assembler source, so the toolkit recognises
-  every mnemonic the real assembler accepts; `just gen` refreshes them.
 
 ### Architecture support
 
+Four architectures, the four that matter in practice:
+
 | Architecture | GOARCH      | File suffix  | Instructions recognised                     |
 |--------------|-------------|--------------|---------------------------------------------|
 | AMD64        | `amd64`     | `_amd64.s`   | 1600 + common opcodes + traditional aliases |
@@ -57,27 +112,64 @@ developer tooling to Plan 9 assembly on amd64, arm64, riscv64 and loong64.
 "Common opcodes" are the instructions shared by every architecture (`RET`,
 `JMP`, `NOP`, `CALL`, `TEXT`, `FUNCDATA`, `PCDATA`, ...).  AMD64 additionally
 carries the traditional conditional-jump spellings (`JZ`, `JNZ`, `JA`, `JC`,
-...) that the assembler accepts as aliases.  Regenerating the tables is one
+...) that the assembler accepts as aliases.  The tables are generated from
-command (`just gen`) and requires only a Go installation; the committed output
+the Go toolchain's own assembler source (`just gen` refreshes them), so
-has no runtime dependency on the toolchain.
+every mnemonic the real assembler accepts is recognised; what the encoder
+can emit today is narrower, and a recognised but unencodable instruction is
+reported as an explicit error, never as a wrong byte.
+
+The same measurement runs over GOROOT's whole assembly corpus:
+`gasm audit-instructions --corpus` reports 108 of 627 files (17.2 %)
+assembling for every target architecture today, with the top failure
+reasons per architecture; the number moves with every release.
+
+## Direction
+
+The plan, in the order it is being worked:
+
+- **Extended instruction support.**  Two layers. First, encoding
+  coverage for every mnemonic the Go toolchain itself accepts, closed in
+  order of how often real code needs each instruction;
+  `gasm audit-instructions` measures the gap. Second, the larger work:
+  an extended instruction set the toolchain does not know at all. The
+  toolchain-derived tables stay generated and untouched; only the
+  extended instructions are hand-maintained, with their own spellings
+  and encoders, verified by execution on real hardware because the
+  toolchain offers no ground truth to compare against. The gaps exist
+  on every architecture, amd64 included.
+- **Full GOOBJ and ELF compilation.**  The destination is a complete,
+  standalone compilation path: linkable ELF objects for consumers outside
+  Go, and GOOBJ objects that `go build` links directly.  Through GOOBJ, a
+  Go program will be able to use machine instructions that the Go
+  toolchain itself does not support; through ELF, Plan 9 assembly becomes
+  usable outside Go entirely.
+- **Platforms: Linux and FreeBSD.**  Linux is supported today on all four
+  architectures and is where the binary builds.  FreeBSD follows: the
+  JIT's executable-memory mapping and the ptrace debugger layer are the
+  two pieces of porting work.  Other unix systems may follow those two.
+- **Four architectures, no more.**  amd64, arm64, riscv64 and loong64.
+  No others are planned.
 
 ## Install
 
 Prebuilt binaries for linux/amd64, linux/arm64, linux/riscv64 and
 linux/loong64 are on the
 [releases page](https://sourcedock.dev/petrbalvin/gasm-devkit/releases).
-From source (Go 1.27 or later):
+From source (Go 1.27.1):
 
 ```sh
 go install sourcedock.dev/petrbalvin/gasm-devkit/cmd/gasm@latest
 ```
 
-Or from a repository checkout, with the development version stamped:
+Or from a repository checkout:
 
 ```sh
-just install-bin
+just install
 ```
 
+The installed binary reports the version the toolchain recorded: the tag
+on a tagged checkout, a pseudo-version naming the commit below one.
+
 ## Quick start
 
 ```sh
@@ -102,9 +194,13 @@ gasm verify --call add --args a=2,b=3 hello_amd64.s   # JIT-call it with argumen
 ```sh
 gasm fmt                                # reformat every .s below here, like go fmt
 gasm fmt    -w kernel_amd64.s           # canonicalise one file in place
+gasm fmt    -l *.s                      # list files whose formatting differs
+gasm fmt    -d kernel_amd64.s           # print a unified diff instead
 gasm lint   *.s                         # static checks
 gasm asm --format elf -o k.o k.s        # assemble to a linkable ELF object
 gasm asm --format goobj -p pkg/path -o k.o k.s   # Go object, consumed by go build
+gasm dis k.s                            # assemble, then list each function
+gasm dis -a amd64 - < dump.bin          # disassemble raw bytes from stdin
 gasm verify --ground-truth k.s          # byte-for-byte vs go tool asm
 gasm verify --fuzz k.s                  # differential fuzz vs the go tool asm build
 gasm debug --func name k.s              # interactive debugger
@@ -132,9 +228,9 @@ infers the target architecture from the file-name suffix
 ## Development
 
 ```sh
-just install      # download module dependencies
+just build        # compile, zero errors and zero warnings
-just build        # go vet + gofmt check, zero errors and zero warnings
+just test         # the suite, no cache, the 80 % coverage floor
-just test         # full suite, race detector, 80 % coverage gate
+just gates        # build, fmt-check, vet, test, race: the definition of done
 just fmt          # gofmt the tree
 just gen          # regenerate the instruction tables from the Go toolchain
 ```
@@ -145,14 +241,16 @@ recipe.
 
 ## Documentation
 
-- [docs/ARCHITECTURE.md](docs/ARCHITECTURE.md): components and data flow
 - [docs/CLI.md](docs/CLI.md): full command reference
+- man pages: `just install-man` installs gasm(1) and one page per command
+  into ~/.local/share/man (MANDIR overrides); `just uninstall-man` removes
+  them
+- [docs/ARCHITECTURE.md](docs/ARCHITECTURE.md): components and data flow
 - [docs/DEVELOPMENT.md](docs/DEVELOPMENT.md): development setup and recipes
-- [docs/DECISIONS.md](docs/DECISIONS.md): deferred design decisions
 - [CHANGELOG.md](CHANGELOG.md): release history
 
 ## Licence
 
-BSD-3-Clause — see [LICENSE](LICENSE).
+BSD-3-Clause; see [LICENSE](LICENSE).
 
 Copyright © 2026 [Petr Balvín](https://petrbalvin.org)

SECURITY.md

@@ -0,0 +1,40 @@
+# Security policy
+
+## Supported versions
+
+Security fixes go to the newest release and to the `development` branch. Older
+releases do not receive them.
+
+| Version | Supported |
+|---|---|
+| 0.33.0 | yes |
+| older releases | no |
+
+## Reporting a vulnerability
+
+**Do not open a public issue for a security problem.** A public report tells everyone
+about the flaw before there is a fix. Report it privately to
+**opensource@petrbalvin.org**.
+
+Include:
+
+- the version or commit you tested, and the platform
+- what the problem is, and what an attacker gains from it
+- the smallest reproducer you have, ideally a test or a single command
+- a suggested fix, if you have one
+
+## What to expect
+
+- A human reads the report, and you get an acknowledgement.
+- You are kept informed while the fix is being made, and told when it ships.
+- The fix is released before the details are published, and the timing is agreed with
+  you.
+- The reporter is credited in the release notes unless they ask otherwise.
+
+## Out of scope
+
+- Findings that require the attacker to already run code as the user, or to have local
+  access.
+- Missing hardening with no demonstrated impact.
+- Flaws in a third-party dependency: report them to that project, and to this one only
+  when this project's use of it makes them reachable.

arch/arm64.go

@@ -29,7 +29,7 @@ func arm64Registers() []Register {
 		regs = append(regs, Register{Name: name, Class: class, Desc: desc})
 	}
 
-	// General-purpose integer registers R0–R30.
+	// General-purpose integer registers R0-R30.
 	for i := 0; i <= 30; i++ {
 		add(fmt.Sprintf("R%d", i), GPR, "64-bit general-purpose register")
 	}

asm/arm64_assemble.go

@@ -12,17 +12,21 @@ import (
 
 // assembleARM64 assembles an AArch64 (arm64) TEXT function body into machine
 // code.  Every instruction is 4 bytes; the MOV pseudo-instruction and the
-// immediate-arithmetic forms expand to 2–4 instructions when the immediate
+// immediate-arithmetic forms expand to 2-4 instructions when the immediate
 // does not fit, so the layout is computed in two passes (sizes, then encoding
 // with resolved branch targets).
 //
 // The emitted bytes match the Go toolchain's arm64 assembler, which is the
 // ground-truth oracle: prologue/epilogue, FP/SP frame mapping, branch
 // encodings and the MOV immediate expansions all follow cmd/internal/obj/
-// arm64's asmout cases.
+// arm64's asmout cases.  One deliberate difference: the stack-growth guard
+// (the morestack check in the prologue and the call back into the runtime in
+// the epilogue) is not emitted, so the bytes match only for NOSPLIT functions
+// or zero-frame leaves, where the toolchain emits no guard either.
 func assembleARM64(t *ast.Text) ([]byte, map[string]int, []Reloc, []LineEntry, []SpadjStep, error) {
 	fi := arm64ComputeFrame(t)
 	prologue := arm64Prologue(fi)
+	guardLen := arm64GuardLen(fi)
 	chain := arm64JumpChain(t)
 	resolve := func(name string) string {
 		if r, ok := chain[name]; ok {
@@ -35,14 +39,14 @@ func assembleARM64(t *ast.Text) ([]byte, map[string]int, []Reloc, []LineEntry, [
 	var spadj []SpadjStep
 
 	// The prologue (3 instructions when a small frame, 4 for large)
-	// raises the SP delta by autosize.
+	// raises the SP delta by autosize.  The guard prefix shifts its PC.
 	if fi.autosize != 0 {
-		spadj = append(spadj, SpadjStep{PC: arm64PrologueSpadjPC(fi), Value: fi.autosize})
+		spadj = append(spadj, SpadjStep{PC: guardLen + arm64PrologueSpadjPC(fi), Value: fi.autosize})
 	}
 
 	// Pass 1: label offsets from the instruction sizes.
 	offsets := map[string]int{}
-	pos := len(prologue)
+	pos := guardLen + len(prologue)
 	for _, stmt := range t.Body {
 		switch s := stmt.(type) {
 		case *ast.Label:
@@ -52,9 +56,25 @@ func assembleARM64(t *ast.Text) ([]byte, map[string]int, []Reloc, []LineEntry, [
 		}
 	}
 
-	// Pass 2: encode.  Relocation offsets are recorded function-relative.
+	// Pass 2: encode.  The guard prefix precedes the prologue; its branches
-	out := append([]byte(nil), prologue...)
+	// target the morestack block at the end of the function, whose position
-	pc := len(prologue)
+	// the first pass has settled.
+	bodyLen := 0
+	{
+		p := guardLen + len(prologue)
+		for _, stmt := range t.Body {
+			if in, ok := stmt.(*ast.Instr); ok {
+				p += arm64InstrSize(in, fi)
+			}
+		}
+		bodyLen = p - (guardLen + len(prologue))
+	}
+	var out []byte
+	if fi.needSplit {
+		out = append(out, arm64GuardBytes(fi, guardLen+len(prologue)+bodyLen)...)
+	}
+	out = append(out, prologue...)
+	pc := guardLen + len(prologue)
 	preCount := len(relocs)
 	var lines []LineEntry
 	for _, stmt := range t.Body {
@@ -67,7 +87,12 @@ func assembleARM64(t *ast.Text) ([]byte, map[string]int, []Reloc, []LineEntry, [
 			return nil, nil, nil, nil, nil, fmt.Errorf("%s: %w", in.Mnemonic.Text, err)
 		}
 		for j := preCount; j < len(relocs); j++ {
-			relocs[j].Off += pc - len(prologue)
+			// Make the relocation offsets function-relative: each instruction
+			// records its reloc offset relative to its own start, and pc is
+			// that instruction's offset from the function start (prologue
+			// included).  After shifts by the same amount.
+			relocs[j].Off += pc
+			relocs[j].After += pc
 		}
 		preCount = len(relocs)
 		lines = append(lines, LineEntry{Offset: pc, Line: in.Pos().Line})
@@ -79,6 +104,12 @@ func assembleARM64(t *ast.Text) ([]byte, map[string]int, []Reloc, []LineEntry, [
 		out = append(out, code...)
 		pc += len(code)
 	}
+	if fi.needSplit {
+		block, blReloc := arm64MoreStackBlock(pc)
+		out = append(out, block...)
+		relocs = append(relocs, blReloc)
+		pc += len(block)
+	}
 	return out, offsets, relocs, lines, spadj, nil
 }
 
@@ -191,7 +222,7 @@ func encodeARM64Instr(instr *ast.Instr, pc int, offsets map[string]int, fi arm64
 			return nil, fmt.Errorf("WORD expects 1 operand, got %d", len(ops))
 		}
 		return a64wordLE(uint32(immFromOperand(ops[0]))), nil
-	case "B":
+	case "B", "JMP":
 		return encodeARM64Branch(mnem, ops, pc, offsets, false, relocs, resolve)
 	case "BL", "CALL":
 		return encodeARM64Branch(mnem, ops, pc, offsets, true, relocs, resolve)
@@ -205,6 +236,11 @@ func encodeARM64Instr(instr *ast.Instr, pc int, offsets map[string]int, fi arm64
 		return encodeARM64BranchCond(mnem, enc.op, ops, pc, offsets, resolve)
 	}
 
+	// Unconditional register branches (BR, BLR).
+	if enc, ok := a64InstrTable[mnem]; ok && enc.format == a64FUncondBranch {
+		return encodeARM64RegBranch(mnem, enc.op, ops)
+	}
+
 	// ADD/SUB immediate.
 	if mnem == "ADD" || mnem == "ADDW" || mnem == "SUB" || mnem == "SUBW" ||
 		mnem == "CMP" || mnem == "CMPW" || mnem == "CMN" || mnem == "CMNW" {
@@ -306,8 +342,27 @@ func encodeARM64Branch(mnem string, ops []*ast.Operand, pc int, offsets map[stri
 	}
 	op := ops[0]
 
-	// External symbol reference: BL sym(SB).
+	// Register-indirect: JMP (R0) is BR R0, CALL (R0) is BLR R0.  The
-	if link && op.Addr.Sym != nil && op.Addr.Sym.Pseudo == "SB" {
+	// toolchain's spelling carries no offset and no index; anything else
+	// is reported rather than silently dropped.
+	if op.Addr.Sym == nil && op.Addr.Base != "" {
+		if op.Addr.Offset != 0 || op.Addr.Index != "" {
+			return nil, fmt.Errorf("%s: invalid indirect branch operand %q", mnem, op.Raw)
+		}
+		rn := arm64RegNum(op.Addr.Base)
+		if rn < 0 {
+			return nil, fmt.Errorf("%s: unknown branch register %q", mnem, op.Addr.Base)
+		}
+		opc := uint32(0) // BR
+		if link {
+			opc = 1 // BLR
+		}
+		return a64wordLE(a64UncondBranch(opc, uint32(rn), 0)), nil
+	}
+
+	// Symbol reference: BL sym(SB), or B sym(SB) for a tail call, against a
+	// relocation (R_CALLARM64 either way).
+	if op.Addr.Sym != nil && op.Addr.Sym.Pseudo == "SB" {
 		if relocs != nil {
 			*relocs = append(*relocs, Reloc{
 				Off:    0,
@@ -317,8 +372,12 @@ func encodeARM64Branch(mnem string, ops []*ast.Operand, pc int, offsets map[stri
 				Kind:   RelArm64Branch,
 			})
 		}
-		// Emit BL with zero offset; the linker fills in the target.
+		// Emit B/BL with zero offset; the linker fills in the target.
-		return a64wordLE(a64Branch(1, 0)), nil
+		bop := uint32(0) // B
+		if link {
+			bop = 1 // BL
+		}
+		return a64wordLE(a64Branch(bop, 0)), nil
 	}
 
 	target := resolve(arm64Label(op))
@@ -337,6 +396,19 @@ func encodeARM64Branch(mnem string, ops []*ast.Operand, pc int, offsets map[stri
 	return a64wordLE(a64Branch(bop, int32(rel))), nil
 }
 
+// encodeARM64RegBranch encodes BR/BLR through a register operand:
+// BR Xn = 0xd61f0000 | Rn<<5, BLR Xn = 0xd63f0000 | Rn<<5.
+func encodeARM64RegBranch(mnem string, baseOp uint32, ops []*ast.Operand) ([]byte, error) {
+	if len(ops) != 1 {
+		return nil, fmt.Errorf("%s expects 1 operand, got %d", mnem, len(ops))
+	}
+	rn := arm64RegNum(operandRegName(ops[0]))
+	if rn < 0 {
+		return nil, fmt.Errorf("%s expects a register operand", mnem)
+	}
+	return a64wordLE(uint32(baseOp) | 31<<16 | uint32(rn)<<5), nil
+}
+
 // encodeARM64BranchCond encodes a conditional branch (B.cond) to a label.
 func encodeARM64BranchCond(mnem string, baseOp uint32, ops []*ast.Operand, pc int, offsets map[string]int, resolve func(string) string) ([]byte, error) {
 	if len(ops) != 1 {
@@ -462,7 +534,7 @@ func encodeARM64AddSubImm(mnem string, ops []*ast.Operand) ([]byte, error) {
 
 // ---- MOV pseudo-instruction ----
 
-// encodeARM64Mov encodes the MOV family — the load/store/immediate workhorse
+// encodeARM64Mov encodes the MOV family, the load/store/immediate workhorse
 // of Go's arm64 assembly.  MOV is an alias of MOVD (the width mnemonics
 // select the access width).  The forms, mirroring the toolchain:
 //
@@ -562,9 +634,9 @@ func arm64MovSize(mnem string, ops []*ast.Operand, fi arm64FrameInfo) int {
 		}
 		_, off := arm64MemWithFrame(mem, fi)
 		// Scaled unsigned offset fits if aligned and in range.
-		lt := a64LoadTable[mnem]
+		lt, ok := a64LoadTable[mnem]
-		if lt.size == 0 {
+		if !ok {
-			lt.size = 3 // default to64-bit for MOV
+			lt = a64LoadTable["MOVD"] // the MOV pseudo is a 64-bit access
 		}
 		scale := int32(1) << uint(lt.size)
 		if off >= 0 && off%scale == 0 && off/scale < 4096 {
@@ -573,7 +645,10 @@ func arm64MovSize(mnem string, ops []*ast.Operand, fi arm64FrameInfo) int {
 		if off >= -256 && off <= 255 {
 			return 4 // unscaled
 		}
-		return 12 // materialise offset + LDR/STR
+		if _, _, _, ok := arm64SplitOffset(off, scale); ok {
+			return 8 // ADD base, REGTMP + access
+		}
+		return 12 // literal pool range: encoding reports it as unsupported
 	default:
 		return 4 // register move
 	}
@@ -793,33 +868,53 @@ func encodeARM64MemOp(mnem string, mem *ast.Operand, reg int, load bool, fi arm6
 	}
 
 	scale := int32(1) << uint(lt.size)
-	if load {
-		// Try scaled unsigned offset first.
-		if off >= 0 && off%scale == 0 {
-			imm12 := uint32(off / scale)
-			if imm12 < 4096 {
-				return a64wordLE(a64LSU(uint32(lt.size), uint32(lt.V), uint32(lt.opc), imm12, uint32(rn), uint32(reg))), nil
-			}
-		}
-		// Try unscaled (9-bit signed).
-		if off >= -256 && off <= 255 {
-			return a64wordLE(a64LSUnscaled(lt.size, lt.V, lt.opc, off, rn, reg)), nil
-		}
-		// Large offset: materialise in R20 (TMP) and use register-offset.
-		return nil, fmt.Errorf("%s: offset %d out of range", mnem, off)
-	}
-	// Store: same encoding but opc bits indicate store.
 	storeOpc := a64StoreOpc(lt)
-	if off >= 0 && off%scale == 0 {
+	var opc int
-		imm12 := uint32(off / scale)
+	if load {
-		if imm12 < 4096 {
+		opc = lt.opc
-			return a64wordLE(a64LSU(uint32(lt.size), uint32(lt.V), uint32(storeOpc), imm12, uint32(rn), uint32(reg))), nil
+	} else {
+		opc = storeOpc
 	}
+	// Scaled unsigned offset first, then the unscaled ±255 form.
+	if off >= 0 && off%scale == 0 && off/scale < 4096 {
+		return a64wordLE(a64LSU(uint32(lt.size), uint32(lt.V), uint32(opc), uint32(off/scale), uint32(rn), uint32(reg))), nil
 	}
 	if off >= -256 && off <= 255 {
-		return a64wordLE(a64LSUnscaled(lt.size, lt.V, storeOpc, off, rn, reg)), nil
+		return a64wordLE(a64LSUnscaled(lt.size, lt.V, opc, off, rn, reg)), nil
 	}
-	return nil, fmt.Errorf("%s: offset %d out of range", mnem, off)
+	// Large offset: materialise the base in REGTMP (R27) the way the
+	// toolchain does and access what remains.
+	addImm, addShift, access, ok := arm64SplitOffset(off, scale)
+	if !ok {
+		return nil, fmt.Errorf("%s: offset %d out of range (literal pool not supported)", mnem, off)
+	}
+	return a64WordsLE(
+		a64AddSub(1, 0, 0, addShift, uint32(addImm), 31, 27), // ADD $addImm<<shift, SP, R27
+		a64LSU(uint32(lt.size), uint32(lt.V), uint32(opc), uint32(access/scale), 27, uint32(reg)),
+	), nil
+}
+
+// arm64SplitOffset decomposes an out-of-range frame offset for a REGTMP
+// base: an ADD (plain, or shifted left by 12) brings SP near the target and
+// the access covers what remains.  ok is false when no decomposition exists
+// (offsets at or beyond 16 MiB, where the toolchain falls back to a literal
+// pool).
+func arm64SplitOffset(off int32, scale int32) (addImm, addShift uint32, access int32, ok bool) {
+	if off < 0 {
+		return 0, 0, 0, false
+	}
+	// Plain ADD: bring SP to within the largest scaled access.
+	l := min(off, 4095*scale)
+	l -= l % scale
+	if a := off - l; a <= 4095 {
+		return uint32(a), 0, l, true
+	}
+	// Shifted ADD: cover everything but the bits the access imm12 carries.
+	rest := off &^ (0xFFF * scale)
+	if rest >= 0 && rest>>12 <= 4095 {
+		return uint32(rest >> 12), 1, off - rest, true
+	}
+	return 0, 0, 0, false
 }
 
 // ---- static symbol references (ADRP + offset) ----
@@ -839,7 +934,9 @@ func encodeARM64SBAddr(sym *ast.Symbol, rd int, relocs *[]Reloc) []byte {
 	)
 }
 
-// encodeARM64SBLoad emits ADRP R20, 0; LDR Rd, [R20, 0] with relocations.
+// encodeARM64SBLoad emits ADRP R27, 0; LDR Rd, [R27, 0] with relocations,
+// matching the toolchain: the scratch register is REGTMP (R27) and the pair
+// carries R_ARM64_PCREL_LDST64.
 func encodeARM64SBLoad(sym *ast.Symbol, rd int, mnem string, relocs *[]Reloc) ([]byte, error) {
 	lt, ok := a64LoadTable[mnem]
 	if !ok {
@@ -847,17 +944,17 @@ func encodeARM64SBLoad(sym *ast.Symbol, rd int, mnem string, relocs *[]Reloc) ([
 	}
 	if relocs != nil {
 		*relocs = append(*relocs,
-			Reloc{Off: 0, After: 0, Name: sym.Name, Kind: RelArm64Addr, Addend: sym.Offset},
+			Reloc{Off: 0, After: 8, Name: sym.Name, Kind: RelArm64LDST64, Addend: sym.Offset},
-			Reloc{Off: 4, After: 4, Name: sym.Name, Kind: RelArm64Addr, Addend: sym.Offset},
 		)
 	}
 	return a64WordsLE(
-		a64ADR(1, 0, 0, 20), // ADRP R20, 0
+		a64ADR(1, 0, 0, 27), // ADRP R27, 0
-		a64LSU(uint32(lt.size), uint32(lt.V), uint32(lt.opc), 0, 20, uint32(rd)), // LDR Rd, [R20, #0]
+		a64LSU(uint32(lt.size), uint32(lt.V), uint32(lt.opc), 0, 27, uint32(rd)), // LDR Rd, [R27, #0]
 	), nil
 }
 
-// encodeARM64SBStore emits ADRP R20, 0; STR Rs, [R20, 0] with relocations.
+// encodeARM64SBStore emits ADRP R27, 0; STR Rs, [R27, 0] with relocations,
+// matching the toolchain's R27 scratch and R_ARM64_PCREL_LDST64 pair.
 func encodeARM64SBStore(sym *ast.Symbol, rs int, mnem string, relocs *[]Reloc) ([]byte, error) {
 	lt, ok := a64LoadTable[mnem]
 	if !ok {
@@ -866,13 +963,12 @@ func encodeARM64SBStore(sym *ast.Symbol, rs int, mnem string, relocs *[]Reloc) (
 	storeOpc := a64StoreOpc(lt)
 	if relocs != nil {
 		*relocs = append(*relocs,
-			Reloc{Off: 0, After: 0, Name: sym.Name, Kind: RelArm64Addr, Addend: sym.Offset},
+			Reloc{Off: 0, After: 8, Name: sym.Name, Kind: RelArm64LDST64, Addend: sym.Offset},
-			Reloc{Off: 4, After: 4, Name: sym.Name, Kind: RelArm64Addr, Addend: sym.Offset},
 		)
 	}
 	return a64WordsLE(
-		a64ADR(1, 0, 0, 20), // ADRP R20, 0
+		a64ADR(1, 0, 0, 27), // ADRP R27, 0
-		a64LSU(uint32(lt.size), uint32(lt.V), uint32(storeOpc), 0, 20, uint32(rs)), // STR Rs, [R20, #0]
+		a64LSU(uint32(lt.size), uint32(lt.V), uint32(storeOpc), 0, 27, uint32(rs)), // STR Rs, [R27, #0]
 	), nil
 }
 
@@ -1092,7 +1188,7 @@ func encodeARM64CSEL(mnem string, baseOp uint32, ops []*ast.Operand) ([]byte, er
 		return a64wordLE(baseOp | uint32(rn)<<16 | invCond<<12 | uint32(rn)<<5 | uint32(rd)), nil
 	}
 
-	// CSEL cond, Rn, Rm, Rd (4 operands) — condition first.
+	// CSEL cond, Rn, Rm, Rd (4 operands), condition first.
 	// Go assembler syntax: CSEL cond, Rn, Rm, Rd
 	// ARM64 encoding: Rm in bits[20:16], Rn in bits[9:5], Rd in bits[4:0].
 	if len(ops) != 4 {

asm/arm64_encode.go

@@ -9,7 +9,7 @@ package asm
 // an opcode constant, and the format selects the bit layout.  The opcode
 // constants and formats are transcribed from the Go toolchain's own arm64
 // backend (cmd/internal/obj/arm64), so the emitted bytes match `go tool asm`
-// exactly — the ground-truth oracle for the verify suite.
+// exactly, the ground-truth oracle for the verify suite.
 //
 // All AArch64 instructions are 32 bits, little-endian.  The formats used here
 // (per the ARM Architecture Reference Manual):
@@ -28,7 +28,7 @@ package asm
 //	ADR/ADRP        p<<31 | 0x10<<24 | immlo<<29 | immhi<<5 | Rd
 
 // arm64RegNum returns the 5-bit register number for an AArch64 register name:
-// R0–R30 (integer), F0–F31 (floating point), and the ABI aliases the
+// R0-R30 (integer), F0-F31 (floating point), and the ABI aliases the
 // runtime's assembly uses.  Returns -1 for an unrecognised name.
 func arm64RegNum(name string) int {
 	switch name {
@@ -99,7 +99,7 @@ func arm64RegNum(name string) int {
 	case "SP":
 		return 31 // SP and ZR share encoding 31; context determines meaning
 	}
-	// F0–F31.
+	// F0-F31.
 	if len(name) >= 1 && name[0] == 'F' {
 		n := 0
 		for i := 1; i < len(name); i++ {

asm/arm64_encode_test.go

@@ -572,3 +572,42 @@ func leWords(b []byte) []uint32 {
 	}
 	return w
 }
+
+// TestArm64IndirectBranch pins the indirect branch forms in a leaf function:
+// JMP (Rn) lowers to BR Rn, matching the toolchain's spelling, and the raw
+// BR/BLR mnemonics encode directly (a gasm superset the toolchain's front
+// end does not accept).  CALL (Rn) shares the BLR path and its non-leaf
+// prologue parity is covered by the ground-truth kernel.
+func TestArm64IndirectBranch(t *testing.T) {
+	src := `#include "textflag.h"
+
+TEXT ·f(SB), NOSPLIT, $0-0
+	JMP (R0)
+	BR R5
+	BLR R6
+	RET
+`
+	f, errs := parser.Parse("test_arm64.s", src)
+	if len(errs) > 0 {
+		t.Fatalf("parse: %v", errs)
+	}
+	img, err := AssembleFileARM64(f)
+	if err != nil {
+		t.Fatalf("AssembleFileARM64: %v", err)
+	}
+	want := []uint32{
+		0xd61f0000, // BR R0
+		0xd61f00a0, // BR R5
+		0xd63f00c0, // BLR R6
+		0xd65f03c0, // RET (BR LR)
+	}
+	got := leWords(img.Code)
+	if len(got) != len(want) {
+		t.Fatalf("word count = %d, want %d", len(got), len(want))
+	}
+	for i := range want {
+		if got[i] != want[i] {
+			t.Errorf("word %d = %08x, want %08x", i, got[i], want[i])
+		}
+	}
+}

asm/arm64_frame.go

@@ -63,6 +63,12 @@ type arm64FrameInfo struct {
 	args     int  // the declared -argsize
 	noSplit  bool // the NOSPLIT flag
 	leaf     bool // no call instructions in the body
+
+	// Stack-split guard state: needSplit mirrors the toolchain, which skips
+	// the check for NOSPLIT functions and auto-marks leaf functions with an
+	// autosize below StackSmall as NOSPLIT.
+	needSplit  bool
+	splitClass int // 0: <=StackSmall, 1: <=StackBig, 2: >StackBig
 }
 
 // arm64ComputeFrame derives the frame layout for a TEXT function.
@@ -80,15 +86,68 @@ func arm64ComputeFrame(t *ast.Text) arm64FrameInfo {
 
 	if fi.frame != 0 || !fi.leaf {
 		fi.autosize = fi.frame + 8 // space for the saved LR
-		if fi.autosize%16 != 0 {
+		// The toolchain always adds an extrasize: 8 when the total leaves a
-			// The toolchain aligns to 16: if autosize%16 == 8, add 8;
+		// 16-byte alignment gap, another 16 when already aligned.
-			// otherwise add whatever is needed.
+		switch fi.autosize % 16 {
+		case 8:
+			fi.autosize += 8
+		case 0:
+			fi.autosize += 16
+		default:
+			// The toolchain rejects unaligned frames; round up so such
+			// sources still assemble.
 			fi.autosize += 16 - (fi.autosize % 16)
 		}
 	}
+	switch {
+	case fi.noSplit:
+	case fi.autosize < stackSmall && fi.leaf:
+		// Auto-NOSPLIT, as the toolchain's leaf mark concludes.
+	default:
+		fi.needSplit = true
+		switch {
+		case fi.autosize <= stackSmall:
+			fi.splitClass = 0
+		case fi.autosize <= stackBig:
+			fi.splitClass = 1
+		default:
+			fi.splitClass = 2
+		}
+	}
 	return fi
 }
 
+// arm64GuardLen returns the byte length of the stack-split guard prefix
+// (zero when the function needs no guard).  The big class materialises
+// framesize-StackSmall into REGTMP, whose MOVZ/MOVK sequence length varies.
+func arm64GuardLen(fi arm64FrameInfo) int {
+	if !fi.needSplit {
+		return 0
+	}
+	switch fi.splitClass {
+	case 0:
+		return 12
+	case 1:
+		return 16
+	default:
+		n, err := arm64LoadImmLen(int64(fi.autosize - stackSmall))
+		if err != nil {
+			return 0
+		}
+		return 4 + n + 4 + 4 + 4 + 4
+	}
+}
+
+// arm64LoadImmLen returns the byte length of the MOVZ/MOVK sequence that
+// loads v into a register.
+func arm64LoadImmLen(v int64) (int, error) {
+	b, err := encodeARM64LoadImm(27, v, "MOVD")
+	if err != nil {
+		return 0, err
+	}
+	return len(b), nil
+}
+
 // arm64IsLeaf reports whether a function contains no call instructions
 // (BL/CALL), matching the toolchain's LEAF mark.
 func arm64IsLeaf(t *ast.Text) bool {
@@ -119,12 +178,47 @@ func arm64Prologue(fi arm64FrameInfo) []byte {
 		)
 	}
 	// Large frame: SUB $autosize, SP, R20; STP (FP,LR), -8(R20); ADD $0, R20, SP; SUB $8, SP, FP
-	return a64WordsLE(
+	ws := arm64SubImmWords(uint32(fi.autosize), 20)
-		a64AddSub(1, 1, 0, 0, uint32(fi.autosize), 31, 20), // SUB $autosize, SP, R20
+	ws = append(ws,
 		a64LSP(2, 0, 0, -1, 30, 20, 29),  // STP FP, LR, [R20, #-8] (opc=2 for 64-bit pair)
 		a64AddSub(1, 0, 0, 0, 0, 20, 31), // ADD $0, R20, SP (= MOV R20, SP)
 		a64AddSub(1, 1, 0, 0, 8, 31, 29), // SUB $8, SP, FP (op=1 for SUB)
 	)
+	return a64WordsLE(ws...)
+}
+
+// arm64SubImmWords emits SUB $imm, SP, Rd: the immediate form when the value
+// fits the imm12 field (plain, or shifted left by 12 when it is a multiple
+// of 4096); otherwise the toolchain materialises it into REGTMP (R27) and
+// subtracts the register in the extended-register form.
+func arm64SubImmWords(imm uint32, rd uint32) []uint32 {
+	if imm <= 0xFFF {
+		return []uint32{a64AddSub(1, 1, 0, 0, imm, 31, rd)}
+	}
+	if imm <= 4095<<12 && imm&0xFFF == 0 {
+		return []uint32{a64AddSub(1, 1, 0, 1, imm>>12, 31, rd)}
+	}
+	mov, err := encodeARM64LoadImm(27, int64(imm), "MOVD")
+	if err != nil {
+		mov = nil
+	}
+	return append(wordsOf(mov), arm64DPExtWords(arm64OpSub, 27, 31, rd))
+}
+
+// arm64AddImmWords emits ADD $imm, SP, Rd with the same imm12, shifted-imm12
+// and REGTMP fallback ladder.
+func arm64AddImmWords(imm uint32, rd uint32) []uint32 {
+	if imm <= 0xFFF {
+		return []uint32{a64AddSub(1, 0, 0, 0, imm, 31, rd)}
+	}
+	if imm <= 4095<<12 && imm&0xFFF == 0 {
+		return []uint32{a64AddSub(1, 0, 0, 1, imm>>12, 31, rd)}
+	}
+	mov, err := encodeARM64LoadImm(27, int64(imm), "MOVD")
+	if err != nil {
+		mov = nil
+	}
+	return append(wordsOf(mov), arm64DPExtWords(arm64OpAdd, 27, 31, rd))
 }
 
 // arm64Return returns the bytes for a RET: the epilogue (restore FP/LR and
@@ -134,10 +228,8 @@ func arm64Return(fi arm64FrameInfo) []byte {
 	if fi.autosize != 0 {
 		if fi.leaf {
 			// Leaf with frame: ADD $autosize-8, SP, FP; ADD $autosize, SP, SP
-			ws = append(ws,
+			ws = append(ws, arm64AddImmWords(uint32(fi.autosize-8), 29)...)
-				a64AddSub(1, 0, 0, 0, uint32(fi.autosize-8), 31, 29), // ADD $autosize-8, SP, FP
+			ws = append(ws, arm64AddImmWords(uint32(fi.autosize), 31)...)
-				a64AddSub(1, 0, 0, 0, uint32(fi.autosize), 31, 31),   // ADD $autosize, SP, SP
-			)
 		} else if fi.autosize <= 0xf0 {
 			// Non-leaf small frame: LDR FP, [SP, #-8]; LDR.P LR, [SP], #autosize
 			ws = append(ws,
@@ -148,8 +240,8 @@ func arm64Return(fi arm64FrameInfo) []byte {
 			// Large frame: LDP -8(SP), (FP, LR); ADD $autosize, SP, SP
 			ws = append(ws,
 				a64LSP(2, 0, 1, -1, 30, 31, 29), // LDP FP, LR, [SP, #-8] (opc=2 for 64-bit pair)
-				a64AddSub(1, 0, 0, 0, uint32(fi.autosize), 31, 31), // ADD $autosize, SP, SP
 			)
+			ws = append(ws, arm64AddImmWords(uint32(fi.autosize), 31)...)
 		}
 	}
 	// RET: BR LR (0xd65f03c0)
@@ -235,3 +327,83 @@ func arm64PostLoad(size, V int, imm9 int32, rn, rt int) uint32 {
 	return uint32(size)<<30 | 7<<27 | uint32(V)<<26 | 1<<22 |
 		1<<10 | (uint32(imm9)&0x1FF)<<12 | uint32(rn&31)<<5 | uint32(rt&31)
 }
+
+// Data-processing (shifted register) base opcodes for the guard blocks.
+const (
+	arm64OpAdd  = 1<<31 | 0<<30 | 0<<29 | 0x0b<<24
+	arm64OpSub  = 1<<31 | 1<<30 | 0<<29 | 0x0b<<24
+	arm64OpSubs = 1<<31 | 1<<30 | 1<<29 | 0x0b<<24
+)
+
+// arm64DPSRWords builds one data-processing (shifted register) word:
+// OP Rm, Rn, Rd in the Go assembler's operand order.
+func arm64DPSRWords(base uint32, rm, rn, rd uint32) uint32 {
+	return base | rm<<16 | rn<<5 | rd
+}
+
+// arm64DPExtWords builds one data-processing (extended register) word, the
+// form the toolchain picks when a large immediate was materialised into
+// REGTMP before the operation: base | 1<<21 | Rm<<16 | UXTX<<13 | Rn<<5 | Rd.
+func arm64DPExtWords(base, rm, rn, rd uint32) uint32 {
+	return base | 1<<21 | rm<<16 | 3<<13 | rn<<5 | rd
+}
+
+// wordsOf converts little-endian instruction bytes back to words.
+func wordsOf(b []byte) []uint32 {
+	ws := make([]uint32, 0, len(b)/4)
+	for i := 0; i+4 <= len(b); i += 4 {
+		ws = append(ws, uint32(b[i])|uint32(b[i+1])<<8|uint32(b[i+2])<<16|uint32(b[i+3])<<24)
+	}
+	return ws
+}
+
+// arm64GuardBytes emits the stack-split guard prefix; blockStart is the
+// function-relative byte address of the morestack block the branches target.
+func arm64GuardBytes(fi arm64FrameInfo, blockStart int) []byte {
+	// MOVD 16(R28), R16 (g.stackguard0)
+	ws := []uint32{a64LSU(3, 0, 1, 2, 28, 16)}
+	br := func(from int, cond uint32) uint32 {
+		return a64BranchCond(int32((blockStart-from)>>2), cond)
+	}
+	switch fi.splitClass {
+	case 0:
+		// CMP R16, RSP in the exact encoding go tool asm emits for it.
+		ws = append(ws, 0xeb3063ff)
+		ws = append(ws, br(8, a64CondLS))
+	case 1:
+		ws = append(ws, a64AddSub(1, 1, 0, 0, uint32(fi.autosize-stackSmall), 31, 17))
+		ws = append(ws, arm64DPSRWords(arm64OpSubs, 16, 17, 31)) // CMP R16, R17
+		ws = append(ws, br(12, a64CondLS))
+	default:
+		mov, err := encodeARM64LoadImm(27, int64(fi.autosize-stackSmall), "MOVD")
+		if err != nil {
+			mov = nil
+		}
+		ws = append(ws, wordsOf(mov)...)
+		ml := len(mov) / 4
+		ws = append(ws, arm64DPExtWords(arm64OpSubs, 27, 31, 17)) // SUBS R17, RSP, R27
+		ws = append(ws, br(8+ml, a64CondLO))
+		ws = append(ws, arm64DPSRWords(arm64OpSubs, 16, 17, 31)) // CMP R16, R17
+		ws = append(ws, br(8+ml+8, a64CondLS))
+	}
+	return a64WordsLE(ws...)
+}
+
+// arm64MoreStackBlock emits the trailing block: MOVD R30, R3 (save LR),
+// BL runtime.morestack_noctxt, B back to the function start.  The BL carries
+// the R_CALLARM64 relocation.
+func arm64MoreStackBlock(blockStart int) ([]byte, Reloc) {
+	ws := []uint32{
+		1<<31 | 1<<29 | 0x0a<<24 | 30<<16 | 31<<5 | 3, // MOVD R30, R3
+		a64Branch(1, 0), // BL, patched by the linker
+	}
+	bPC := blockStart + 8
+	ws = append(ws, a64Branch(0, int32(-bPC>>2))) // B back to the entry
+	reloc := Reloc{
+		Off:   blockStart + 4,
+		After: blockStart + 8,
+		Name:  "runtime\u00b7morestack_noctxt",
+		Kind:  RelArm64Branch,
+	}
+	return a64WordsLE(ws...), reloc
+}

asm/arm64_reloc_test.go

@@ -0,0 +1,126 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+package asm
+
+import (
+	"encoding/binary"
+	"testing"
+
+	"sourcedock.dev/petrbalvin/gasm-devkit/parser"
+)
+
+// parseArm64File is a helper assembling one arm64 source file.
+func parseArm64File(t *testing.T, src string) *Image {
+	t.Helper()
+	f, errs := parser.Parse("k_arm64.s", src)
+	if len(errs) > 0 {
+		t.Fatalf("parse: %v", errs)
+	}
+	img, err := AssembleFileARM64(f)
+	if err != nil {
+		t.Fatalf("assemble: %v", err)
+	}
+	return img
+}
+
+// TestArm64RelocOffsetsIncludePrologue pins the function-relative relocation
+// offsets of a framed function: the offsets used to exclude the prologue, so
+// every relocation landed on a prologue instruction in the GOOBJ/ELF output.
+// The function calls an external, so it is a non-leaf and carries the
+// stack-split guard (12 bytes, small class) before the prologue.
+func TestArm64RelocOffsetsIncludePrologue(t *testing.T) {
+	img := parseArm64File(t, "TEXT \u00b7f(SB), $16-0\n"+
+		"\tBL ext\u00b7foo(SB)\n"+
+		"\tMOVD $gdata(SB), R5\n"+
+		"\tMOVD $extsym(SB), R6\n"+
+		"\tRET\n"+
+		"GLOBL gdata(SB), $8\n")
+	fn := img.Funcs[0]
+
+	// Layout: 12-byte guard, 12-byte prologue, BL (24), ADRP+ADD (28, 32),
+	// ADRP+ADD (36, 40), 12-byte epilogue with RET, 12-byte morestack block.
+	want := []struct {
+		off      int
+		after    int
+		name     string
+		kind     RelocKind
+		external bool
+	}{
+		{24, 28, "foo", RelArm64Branch, true},
+		{28, 28, "gdata", RelArm64Addr, false},
+		{32, 32, "gdata", RelArm64Addr, false},
+		{36, 36, "extsym", RelArm64Addr, true},
+		{40, 40, "extsym", RelArm64Addr, true},
+		{60, 64, "runtime\u00b7morestack_noctxt", RelArm64Branch, true},
+	}
+	if len(fn.Relocs) != len(want) {
+		t.Fatalf("relocs = %d, want %d", len(fn.Relocs), len(want))
+	}
+	for i, w := range want {
+		r := fn.Relocs[i]
+		if r.Off != w.off || r.After != w.after || r.Name != w.name || r.Kind != w.kind || r.External != w.external {
+			t.Errorf("reloc %d = {off %d after %d name %q kind %d ext %v}, want {off %d after %d name %q kind %d ext %v}",
+				i, r.Off, r.After, r.Name, r.Kind, r.External, w.off, w.after, w.name, w.kind, w.external)
+		}
+	}
+
+	// The BL with a zero offset sits exactly at the first reloc site.
+	code := img.Code[fn.Offset : fn.Offset+fn.Size]
+	if w := binary.LittleEndian.Uint32(code[24:28]); w != 0x94000000 {
+		t.Errorf("BL word = %08x, want 94000000", w)
+	}
+}
+
+// TestArm64SBLoadStoreMatchesToolchain pins the ADRP scratch register
+// (REGTMP, R27) and the LDST64 relocation kind for sym loads and stores,
+// against the bytes go tool asm emits for MOVD sym(SB), R5.
+func TestArm64SBLoadStoreMatchesToolchain(t *testing.T) {
+	img := parseArm64File(t, "TEXT \u00b7ld(SB), NOSPLIT, $0\n"+
+		"\tMOVD sym(SB), R5\n"+
+		"\tMOVD R5, sym(SB)\n"+
+		"\tRET\n"+
+		"GLOBL sym(SB), $8\n")
+	fn := img.Funcs[0]
+	code := img.Code[fn.Offset : fn.Offset+fn.Size]
+
+	// go tool asm: ADRP 0(PC), R27 (9000001b); MOVD (R27), R5 (f9400365);
+	// ADRP 0(PC), R27; MOVD R5, (R27) (f9000365).
+	for off, want := range map[int]uint32{0: 0x9000001b, 4: 0xf9400365, 8: 0x9000001b, 12: 0xf9000365} {
+		if got := binary.LittleEndian.Uint32(code[off : off+4]); got != want {
+			t.Errorf("word at %d = %08x, want %08x", off, got, want)
+		}
+	}
+
+	if len(fn.Relocs) != 2 {
+		t.Fatalf("relocs = %d, want 2", len(fn.Relocs))
+	}
+	for i, w := range []struct{ off, after int }{{0, 8}, {8, 16}} {
+		r := fn.Relocs[i]
+		if r.Kind != RelArm64LDST64 {
+			t.Errorf("reloc %d kind = %d, want RelArm64LDST64 (%d)", i, r.Kind, RelArm64LDST64)
+		}
+		if r.Off != w.off || r.After != w.after {
+			t.Errorf("reloc %d = {off %d after %d}, want {off %d after %d}", i, r.Off, r.After, w.off, w.after)
+		}
+	}
+}
+
+// TestArm64GOObjRelocTypes checks that GOOBJ emission succeeds with the new
+// relocation kinds in play; the detailed layout is covered by the goobj tests.
+func TestArm64GOObjRelocTypes(t *testing.T) {
+	img := parseArm64File(t, "TEXT \u00b7ld(SB), NOSPLIT, $0\n"+
+		"\tMOVD sym(SB), R5\n"+
+		"\tMOVD R5, sym(SB)\n"+
+		"\tRET\n"+
+		"GLOBL sym(SB), $8\n")
+	obj, err := img.GOObjectAARCH64("testpkg", "k_arm64.s")
+	if err != nil {
+		t.Fatalf("GOObjectAARCH64: %v", err)
+	}
+	if len(obj) == 0 {
+		t.Fatal("empty object")
+	}
+	// The detailed layout is covered by the goobj tests; here we only pin
+	// that emission succeeds with the new relocation kinds in play.
+}

asm/assemble.go

@@ -22,6 +22,11 @@ import (
 // FP/SP frame-relative operands, and local-label jumps.  SB (global symbol)
 // operands require relocations and are not yet supported; the SIMD (VEX/AVX2)
 // integer and shuffle/extract/permute/move set is in.
+//
+// Like the other architectures, the stack-growth guard (the morestack check
+// in the prologue and the call back into the runtime in the epilogue) is not
+// emitted: the bytes match go tool asm only for NOSPLIT functions or
+// zero-frame leaves, where the toolchain emits no guard either.
 func Assemble(t *ast.Text) ([]byte, map[string]int, error) {
 	code, _, labels, _, _, err := assemble(t, nil)
 	return code, labels, err
@@ -31,7 +36,7 @@ func Assemble(t *ast.Text) ([]byte, map[string]int, error) {
 // the set of static symbols a GLOBL in the same file defines.  A nil link
 // rejects SB operands outright (single-function assembly cannot resolve
 // them).  When allowExternal is set, a reference to a symbol no GLOBL in the
-// file defines is recorded as an external relocation instead of failing —
+// file defines is recorded as an external relocation instead of failing
 // the object-file emitters resolve it at link time.
 type linkInfo struct {
 	symbols       map[string]bool
@@ -46,6 +51,7 @@ type sbPatch struct {
 	after  int
 	name   string
 	addend int64
+	kind   RelocKind
 }
 
 // spadjStep is one stack-adjustment boundary within a function: Value is the
@@ -70,13 +76,18 @@ func assemble(t *ast.Text, link *linkInfo) ([]byte, []sbPatch, map[string]int, [
 		return name
 	}
 
-	// Layout: iterate jump sizes to a fixed point.
+	// Layout: iterate jump sizes to a fixed point.  The stack-split guard
+	// prefix and the trailing morestack block participate in the iteration:
+	// their conditional branches relax from rel8 to rel32 when the body
+	// outgrows the short form.
 	long := make([]bool, len(t.Body))
 	sizes := make([]int, len(t.Body))
 	offsets := map[string]int{}
 	pcs := make([]int, len(t.Body))
+	var guardJBlong, guardJBElong, moreJMPlong bool
 	for {
-		pos := len(fi.prologue)
+		guard := fi.guardLen(guardJBlong, guardJBElong)
+		pos := guard + len(fi.prologue)
 		for i, stmt := range t.Body {
 			switch s := stmt.(type) {
 			case *ast.Label:
@@ -91,6 +102,7 @@ func assemble(t *ast.Text, link *linkInfo) ([]byte, []sbPatch, map[string]int, [
 				pos += sz
 			}
 		}
+		bodyLen := pos - (guard + len(fi.prologue))
 		// Expand any short jump whose displacement no longer fits rel8.
 		changed := false
 		for i, stmt := range t.Body {
@@ -116,25 +128,75 @@ func assemble(t *ast.Text, link *linkInfo) ([]byte, []sbPatch, map[string]int, [
 				changed = true
 			}
 		}
+		// The guard's conditional branches target the morestack block, which
+		// starts right after the body: the JBE measures from the end of the
+		// guard, so its displacement is the prologue plus the body.
+		if !guardJBElong && !fits8(int64(len(fi.prologue)+bodyLen)) {
+			guardJBElong = true
+			changed = true
+		}
+		if fi.splitClass == 2 && !guardJBlong {
+			// The underflow JB sits before the CMPQ; its displacement spans
+			// the rest of the guard plus the prologue and the body.
+			jbLen := 2
+			if guardJBlong {
+				jbLen = 6
+			}
+			rest := fi.guardLen(guardJBlong, guardJBElong) - (9 + 3 + 7 + jbLen)
+			if !fits8(int64(rest + len(fi.prologue) + bodyLen)) {
+				guardJBlong = true
+				changed = true
+			}
+		}
+		// The morestack JMP returns to the function start, so its
+		// displacement is the negated distance from its own end.
+		if !moreJMPlong {
+			jmpLen := 2
+			if moreJMPlong {
+				jmpLen = 5
+			}
+			if !fits8(-int64(guard + len(fi.prologue) + bodyLen + 5 + jmpLen)) {
+				moreJMPlong = true
+				changed = true
+			}
+		}
 		if !changed {
 			break
 		}
 	}
 
-	// Pass 2: emit.
+	// Pass 2: emit.  The guard comes first, then the prologue, the body and
-	out := append([]byte(nil), fi.prologue...)
+	// the morestack block.
+	guardLen := fi.guardLen(guardJBlong, guardJBElong)
+	bodyLen := 0
+	{
+		pos := guardLen + len(fi.prologue)
+		for i, stmt := range t.Body {
+			if _, ok := stmt.(*ast.Instr); ok {
+				pos += sizes[i]
+			}
+		}
+		bodyLen = pos - (guardLen + len(fi.prologue))
+	}
+	var out []byte
 	var patches []sbPatch
+	if fi.needSplit {
+		guard, tlsPatch := buildGuard(fi, int32(len(fi.prologue)+bodyLen), int32(fi.guardLen(guardJBlong, guardJBElong)-(9+3+7+2)+len(fi.prologue)+bodyLen))
+		out = append(out, guard...)
+		patches = append(patches, tlsPatch)
+	}
+	out = append(out, fi.prologue...)
 	var steps []spadjStep
 	var lines []LineEntry
 	if fi.useFP {
 		// PUSHQ BP saves the return-address-relative base (+8); the MOVQ
 		// changes nothing; SUBQ $size, SP completes the frame.
 		steps = append(steps,
-			spadjStep{1, 8},
+			spadjStep{guardLen + 1, 8},
-			spadjStep{len(fi.prologue), 8 + fi.size},
+			spadjStep{guardLen + len(fi.prologue), 8 + fi.size},
 		)
 	}
-	pos := len(fi.prologue)
+	pos := guardLen + len(fi.prologue)
 	for i, stmt := range t.Body {
 		s, ok := stmt.(*ast.Instr)
 		if !ok {
@@ -156,11 +218,32 @@ func assemble(t *ast.Text, link *linkInfo) ([]byte, []sbPatch, map[string]int, [
 		if len(code) != sizes[i] {
 			return nil, nil, nil, nil, nil, fmt.Errorf("%s: size mismatch (%d vs %d)", s.Mnemonic.Text, len(code), sizes[i])
 		}
+		if strings.ToUpper(s.Mnemonic.Text) == "CALL" {
+			for k := range ps {
+				ps[k].kind = RelCall
+			}
+		}
 		patches = append(patches, ps...)
 		lines = append(lines, LineEntry{Offset: pos, Line: s.Pos().Line})
 		out = append(out, code...)
 		pos += len(code)
 	}
+	if fi.needSplit {
+		// The morestack block: CALL runtime.morestack_noctxt, then a JMP
+		// back to the function entry.
+		jmpLen := 2
+		if moreJMPlong {
+			jmpLen = 5
+		}
+		jmpDisp := -int64(pos + 5 + jmpLen)
+		suffix, callPatch := buildMoreStack(int32(jmpDisp))
+		callPatch.off += pos
+		callPatch.after = pos + 5
+		patches = append(patches, callPatch)
+		out = append(out, suffix...)
+		pos += len(suffix)
+	}
+	_ = pos
 	return out, patches, offsets, steps, lines, nil
 }
 
@@ -224,16 +307,48 @@ type frameInfo struct {
 	spAdjust int64 // x-N(SP) becomes (spAdjust - N)(SP)
 	prologue []byte
 	epilogue []byte
+
+	// Stack-split guard state (matching the toolchain's stacksplit): needSplit
+	// is false for NOSPLIT functions and for leaf functions whose frame is
+	// below StackSmall, which the toolchain auto-marks NOSPLIT.
+	needSplit  bool
+	splitClass int // 0: <=StackSmall, 1: <=StackBig, 2: >StackBig
+	framesize  int // the size the guard checks: frame+8 for framed functions
 }
 
+// Stack-frame size classes from runtime/stack.go.
+const (
+	stackSmall = 128
+	stackBig   = 4096
+)
+
+// sbPatch gains a kind so the emitters can tell CALL and TLS patches from
+// plain PC-relative displacements.
+
 // computeFrame derives the frame layout, matching the Go assembler's default
-// (a frame pointer is used whenever the function has a non-zero frame).
+// (a frame pointer is used whenever the function has a non-zero frame).  It
+// also decides whether the function needs the stack-split guard, mirroring
+// obj6: a NOSPLIT function never splits, and a leaf function whose frame is
+// below StackSmall is auto-marked NOSPLIT.  One deliberate deviation: the
+// toolchain treats zero-argument runtime calls (duffcopy and friends) as
+// leaf-compatible; here any CALL makes the function a non-leaf.
 func computeFrame(t *ast.Text) frameInfo {
 	fi := frameInfo{}
 	if t.Frame != nil && t.Frame.Imm.HasVal {
 		fi.size = int(t.Frame.Imm.Val)
 	}
-	if fi.size > 0 {
+	if fi.size == 0 && hasCall(t) {
+		// The toolchain gives a frameless function containing a CALL an
+		// 8-byte frame for the pushed base pointer: the prologue saves BP
+		// with no stack adjustment, every RET pops it back, FP references
+		// pass one extra slot, and the virtual SP is the hardware SP.
+		fi.size = 8
+		fi.useFP = true
+		fi.fpAdjust = int64(fi.size) + 16 // return address + saved BP + args base
+		fi.spAdjust = 0
+		fi.prologue = []byte{0x55, 0x48, 0x89, 0xE5} // PUSHQ BP; MOVQ SP, BP
+		fi.epilogue = []byte{0x5D}                   // POPQ BP
+	} else if fi.size > 0 {
 		fi.useFP = true
 		fi.fpAdjust = int64(fi.size) + 16 // frame + saved BP + return address
 		fi.spAdjust = int64(fi.size)
@@ -242,9 +357,141 @@ func computeFrame(t *ast.Text) frameInfo {
 	} else {
 		fi.fpAdjust = 8 // return address only
 	}
+
+	noSplit := false
+	for _, f := range t.Flags {
+		if strings.EqualFold(f, "NOSPLIT") {
+			noSplit = true
+		}
+	}
+	// The toolchain's autoffset: the frame plus the saved base pointer.
+	framesize := fi.size
+	if framesize > 0 {
+		framesize += 8
+	}
+	switch {
+	case noSplit:
+	case framesize < stackSmall && !hasCall(t):
+		// Auto-NOSPLIT, as the toolchain's leaf search concludes.
+	default:
+		fi.needSplit = true
+		fi.framesize = framesize
+		switch {
+		case framesize <= stackSmall:
+			fi.splitClass = 0
+		case framesize <= stackBig:
+			fi.splitClass = 1
+		default:
+			fi.splitClass = 2
+		}
+	}
 	return fi
 }
 
+// hasCall reports whether the function body contains a CALL instruction.
+func hasCall(t *ast.Text) bool {
+	for _, stmt := range t.Body {
+		in, ok := stmt.(*ast.Instr)
+		if !ok {
+			continue
+		}
+		if strings.ToUpper(in.Mnemonic.Text) == "CALL" {
+			return true
+		}
+	}
+	return false
+}
+
+// guardLen returns the byte length of the stack-split guard prefix.  The
+// final conditional branch (JBE, and JB in the big class) is 2 bytes in the
+// short form and 6 in the long form.
+func (fi frameInfo) guardLen(jbLong, jbeLong bool) int {
+	if !fi.needSplit {
+		return 0
+	}
+	jb, jbe := 2, 2
+	if jbLong {
+		jb = 6
+	}
+	if jbeLong {
+		jbe = 6
+	}
+	switch fi.splitClass {
+	case 0:
+		return 9 + 4 + jbe
+	case 1:
+		return 9 + 8 + 4 + jbe
+	default:
+		return 9 + 3 + 7 + jb + 4 + jbe
+	}
+}
+
+// moreLen returns the byte length of the trailing morestack block: the CALL
+// (always rel32) plus the JMP back to the function start.
+func moreLen(jmpLong bool) int {
+	jmp := 2
+	if jmpLong {
+		jmp = 5
+	}
+	return 5 + jmp
+}
+
+// buildGuard emits the stack-split guard prefix.  jbeDisp and jbDisp are the
+// already-computed displacements of the conditional branches that jump to the
+// morestack block (unused in classes without them).  The TLS load carries a
+// R_TLS_LE patch site at offset 5.
+func buildGuard(fi frameInfo, jbeDisp, jbDisp int32) ([]byte, sbPatch) {
+	out := []byte{
+		0x64, 0x4c, 0x8b, 0x34, 0x25, // MOVQ FS:0, R14
+		0, 0, 0, 0, // TLS slot offset, filled by the linker
+	}
+	tls := sbPatch{off: 5, after: 9, kind: RelTLSLE}
+	jmp := func(op8, op32 byte, disp int32) []byte {
+		if disp >= -128 && disp <= 127 {
+			return []byte{op8, byte(disp)}
+		}
+		return append([]byte{0x0F, op32}, le32(int64(disp))...)
+	}
+	switch fi.splitClass {
+	case 0:
+		// CMPQ SP, 16(R14)
+		out = append(out, 0x49, 0x3b, 0x66, 0x10)
+		out = append(out, jmp(0x76, 0x86, jbeDisp)...)
+	case 1:
+		// LEAQ -(framesize-StackSmall)(SP), R12; CMPQ R12, 16(R14)
+		out = append(out, 0x4c, 0x8d, 0xa4, 0x24)
+		out = append(out, le32(-int64(fi.framesize-stackSmall))...)
+		out = append(out, 0x4d, 0x3b, 0x66, 0x10)
+		out = append(out, jmp(0x76, 0x86, jbeDisp)...)
+	default:
+		// MOVQ SP, R12; SUBQ $(framesize-StackSmall), R12; JB; CMPQ R12, 16(R14)
+		out = append(out, 0x49, 0x89, 0xe4)
+		out = append(out, 0x49, 0x81, 0xec)
+		out = append(out, le32(int64(fi.framesize-stackSmall))...)
+		out = append(out, jmp(0x72, 0x82, jbDisp)...)
+		out = append(out, 0x4d, 0x3b, 0x66, 0x10)
+		out = append(out, jmp(0x76, 0x86, jbeDisp)...)
+	}
+	return out, tls
+}
+
+// buildMoreStack emits the trailing block: CALL runtime.morestack_noctxt
+// (patched by the linker) and a JMP back to the function start.
+func buildMoreStack(jmpDisp int32) ([]byte, sbPatch) {
+	out := []byte{0xE8, 0, 0, 0, 0}
+	call := sbPatch{off: 1, after: 5, name: "runtime\u00b7morestack_noctxt", kind: RelCall}
+	out = append(out, jmpBytes(jmpDisp)...)
+	return out, call
+}
+
+// jmpBytes encodes a near JMP in the short or long form.
+func jmpBytes(disp int32) []byte {
+	if disp >= -128 && disp <= 127 {
+		return []byte{0xEB, byte(disp)}
+	}
+	return append([]byte{0xE9}, le32(int64(disp))...)
+}
+
 // prologueBytes emits: PUSHQ BP; MOVQ SP, BP; SUBQ $size, SP.
 func prologueBytes(size int) []byte {
 	out := []byte{0x55, 0x48, 0x89, 0xE5} // PUSHQ BP; MOVQ SP, BP
@@ -258,14 +505,11 @@ func epilogueBytes(size int) []byte {
 }
 
 func subSP(size int) []byte { // SUBQ $size, SP
+	// imm8 holds -128..127; anything larger takes the imm32 form, exactly as
+	// the Go assembler encodes it (verified for 8, 128, 200 and 255).
 	if size >= -128 && size <= 127 {
 		return []byte{0x48, 0x83, 0xEC, byte(int8(size))}
 	}
-	// 128..255 do not fit SUB's unsigned imm8, but the Go assembler
-	// switches to ADDQ $-size, SP whose sign-extended imm8 does.
-	if size >= -255 && size <= 255 {
-		return []byte{0x48, 0x83, 0xC4, byte(int8(-size))}
-	}
 	return append([]byte{0x48, 0x81, 0xEC}, le32(int64(size))...)
 }
 
@@ -282,6 +526,16 @@ func addSP(size int) []byte { // ADDQ $size, SP
 func instrSize(s *ast.Instr, fi frameInfo, long bool, link *linkInfo) (int, error) {
 	mnem := strings.ToUpper(s.Mnemonic.Text)
 	if isJumpMnemonic(mnem) {
+		if (mnem == "CALL" || mnem == "JMP") && isSBCall(s) {
+			return 5, nil // opcode + rel32, always the long form
+		}
+		if (mnem == "CALL" || mnem == "JMP") && indirectJumpTarget(s) {
+			code, err := encodeIndirectJump(s, mnem)
+			if err != nil {
+				return 0, err
+			}
+			return len(code), nil
+		}
 		return jumpSize(mnem, long), nil
 	}
 	code, _, err := encodeInstr(s, 0, nil, fi, false, nil, link)
@@ -331,6 +585,33 @@ func encodeInstr(s *ast.Instr, pc int, offsets map[string]int, fi frameInfo, lon
 	var ps []sbPatch
 	var err error
 	if isJumpMnemonic(mnem) {
+		if (mnem == "CALL" || mnem == "JMP") && isSBCall(s) {
+			// CALL/JMP sym(SB): a rel32 call (or tail call) against a
+			// static or external symbol, resolved by the file-level layout
+			// or the linker.
+			code, ps, err = encodeSBCall(s, link)
+			if err != nil {
+				return nil, nil, err
+			}
+			for i := range ps {
+				ps[i].kind = RelCall
+			}
+			body := pc + len(prefix)
+			for i := range ps {
+				ps[i].off += body
+				ps[i].after = body + len(code)
+			}
+			return append(prefix, code...), ps, nil
+		}
+		if (mnem == "CALL" || mnem == "JMP") && indirectJumpTarget(s) {
+			// JMP/CALL through a register or memory: no relocation and no
+			// label to resolve, the operand fully determines the bytes.
+			code, err = encodeIndirectJump(s, mnem)
+			if err != nil {
+				return nil, nil, err
+			}
+			return append(prefix, code...), nil, nil
+		}
 		code, err = encodeJump(s, mnem, pc+len(prefix), offsets, long, resolve)
 	} else {
 		code, ps, err = encodeNormal(s, fi, link)
@@ -412,6 +693,37 @@ func encodeJump(s *ast.Instr, mnem string, pc int, offsets map[string]int, long
 	}
 }
 
+// isSBCall reports whether the CALL operand is a symbol reference.
+func isSBCall(s *ast.Instr) bool {
+	return len(s.Operands) == 1 && s.Operands[0].Kind == ast.OpAddr &&
+		s.Operands[0].Addr.Sym != nil && s.Operands[0].Addr.Sym.Pseudo == "SB"
+}
+
+// encodeSBCall encodes CALL sym(SB) as E8 rel32 with a patch site.
+func encodeSBCall(s *ast.Instr, link *linkInfo) ([]byte, []sbPatch, error) {
+	o, err := operandFromAST(s.Operands[0], 8, frameInfo{}, link)
+	if err != nil {
+		return nil, nil, err
+	}
+	m, ok := o.(sbMem)
+	if !ok {
+		return nil, nil, fmt.Errorf("CALL: unsupported operand")
+	}
+	opcode := []byte{0xE8}
+	if strings.ToUpper(s.Mnemonic.Text) == "JMP" {
+		opcode = []byte{0xE9} // a tail call, no return address pushed
+	}
+	e := &enc{}
+	if err := e.emit(&instr{opcode: opcode, modrm: -1, sib: -1, disp: le32(0), sb: &sbRef{name: m.name, addend: m.addend}}); err != nil {
+		return nil, nil, err
+	}
+	ps := make([]sbPatch, len(e.patches))
+	for i, p := range e.patches {
+		ps[i] = sbPatch{off: p.off, name: p.name, addend: p.addend, kind: RelCall}
+	}
+	return e.out, ps, nil
+}
+
 // labelName extracts a local-label name from a jump operand.
 func labelName(op *ast.Operand) (string, bool) {
 	if op.Kind == ast.OpAddr && op.Addr.Sym != nil && op.Addr.Sym.Pseudo == "" &&
@@ -421,6 +733,44 @@ func labelName(op *ast.Operand) (string, bool) {
 	return "", false
 }
 
+// indirectJumpTarget reports whether the JMP/CALL operand addresses a
+// register or a memory location rather than a label or a static symbol.
+// A bare identifier is a register when the register table knows the name and
+// a label otherwise, which is exactly how the parser cannot distinguish them.
+func indirectJumpTarget(s *ast.Instr) bool {
+	if len(s.Operands) != 1 || s.Operands[0].Kind != ast.OpAddr {
+		return false
+	}
+	a := s.Operands[0].Addr
+	if a.Base != "" || a.Index != "" {
+		return true
+	}
+	if a.Sym != nil && a.Sym.Pseudo == "" && a.Sym.Name != "" {
+		if _, ok := ParseReg(a.Sym.Name); ok {
+			return true
+		}
+	}
+	return false
+}
+
+// encodeIndirectJump assembles a JMP/CALL through a register or memory
+// operand, which carries no relocation and no label to resolve.
+func encodeIndirectJump(s *ast.Instr, mnem string) ([]byte, error) {
+	ops := make([]Operand, len(s.Operands))
+	for i, op := range s.Operands {
+		o, err := operandFromAST(op, 8, frameInfo{}, nil)
+		if err != nil {
+			return nil, err
+		}
+		ops[i] = o
+	}
+	e := &enc{}
+	if err := e.encodeIndirectBranch(mnem, ops); err != nil {
+		return nil, err
+	}
+	return e.out, nil
+}
+
 // spReg is the hardware stack pointer used to realise FP/SP pseudo-operands.
 var spReg = Reg{idx: 4, size: 8}
 

asm/assemble_test.go

@@ -4,6 +4,7 @@
 package asm
 
 import (
+	"bytes"
 	"strings"
 	"testing"
 
@@ -201,8 +202,8 @@ TEXT ·withframe(SB), NOSPLIT, $16-16
 }
 
 // TestAssembleVexKernel assembles the horizontal-sum reduction the go-flac
-// kernels end with — exercising the VEX moves, shuffle and extract forms
+// kernels end with; exercising the VEX moves, shuffle and extract forms
-// through the full parser → encoder path — and checks the output is
+// through the full parser → encoder path; and checks the output is
 // byte-identical to the Go assembler's.
 func TestAssembleVexKernel(t *testing.T) {
 	fn := firstText(t, `
@@ -351,3 +352,26 @@ TEXT ·pf(SB), NOSPLIT, $0
 		t.Errorf("PREFETCHT0 bytes: got %s, want 0f 18 0b", hex)
 	}
 }
+
+// TestSubSPEncodings pins the prologue SUB against the bytes go tool asm
+// emits for SUBQ $size, SP: imm8 for -128..127, the imm32 form for anything
+// larger.  The intermediate 129..255 range used to encode an ADD with a
+// truncated immediate, moving SP the wrong way.
+func TestSubSPEncodings(t *testing.T) {
+	for _, tt := range []struct {
+		size int
+		want []byte
+	}{
+		{8, []byte{0x48, 0x83, 0xEC, 0x08}},
+		{127, []byte{0x48, 0x83, 0xEC, 0x7F}},
+		{128, []byte{0x48, 0x81, 0xEC, 0x80, 0x00, 0x00, 0x00}},
+		{200, []byte{0x48, 0x81, 0xEC, 0xC8, 0x00, 0x00, 0x00}},
+		{255, []byte{0x48, 0x81, 0xEC, 0xFF, 0x00, 0x00, 0x00}},
+		{4096, []byte{0x48, 0x81, 0xEC, 0x00, 0x10, 0x00, 0x00}},
+	} {
+		got := subSP(tt.size)
+		if !bytes.Equal(got, tt.want) {
+			t.Errorf("subSP(%d) = %x, want %x", tt.size, got, tt.want)
+		}
+	}
+}

asm/elf.go

@@ -12,7 +12,7 @@ import (
 // Image: a .text section holding the function bodies, a .data section
 // holding the GLOBL initialisers, a symbol table with one symbol per TEXT
 // and GLOBL (file-local <> symbols are STB_LOCAL, the rest STB_GLOBAL), and
-// a .rela.text relocation table — one R_X86_64_PC32 entry per static-symbol
+// a .rela.text relocation table, one R_X86_64_PC32 entry per static-symbol
 // reference, internal references resolving against the local data symbols
 // and external ones against undefined globals.  The output links with the
 // system toolchain (cc/ld) the way a hand-assembled .o would.
@@ -43,6 +43,7 @@ const (
 	stInfoShift = 4
 
 	rX8664PC32    = 2
+	rX8664TPOFF32 = 20
 )
 
 // elfSym is one symbol-table entry in construction.
@@ -71,7 +72,7 @@ func (img *Image) ELFObject() ([]byte, error) {
 
 	// Build the symbol table: the null entry and the two section symbols
 	// come first, then the local symbols (static TEXT and GLOBL), then the
-	// globals (exported TEXT and GLOBL, and the undefined externals) — ELF
+	// globals (exported TEXT and GLOBL, and the undefined externals), ELF
 	// requires every local to precede every global, and sh_info records the
 	// boundary.  symIdx maps a symbol name to its index for the relocations.
 	var locals, globals []elfSym
@@ -125,11 +126,19 @@ func (img *Image) ELFObject() ([]byte, error) {
 	type elfRela struct {
 		off    uint64
 		sym    int
+		typ    uint32
 		addend int64
 	}
 	var relas []elfRela
 	for _, fn := range img.Funcs {
 		for _, r := range fn.Relocs {
+			var typ uint32 = rX8664PC32
+			if r.Kind == RelTLSLE {
+				// R_X86_64_TPOFF32 resolves to the local-exec TLS offset and
+				// carries no symbol.
+				relas = append(relas, elfRela{off: uint64(fn.Offset + r.Off), sym: 0, typ: rX8664TPOFF32})
+				continue
+			}
 			idx, ok := symIdx[r.Name]
 			if !ok {
 				return nil, fmt.Errorf("relocation references unknown symbol %q", r.Name)
@@ -137,6 +146,7 @@ func (img *Image) ELFObject() ([]byte, error) {
 			relas = append(relas, elfRela{
 				off: uint64(fn.Offset + r.Off),
 				sym: idx,
+				typ: typ,
 				// R_X86_64_PC32 computes S + A − P with P the patch site; the
 				// assembler measures the symbol from the instruction end,
 				// After − Off bytes past the field, so the addend carries
@@ -218,7 +228,7 @@ func (img *Image) ELFObject() ([]byte, error) {
 	shstrOff := len(out)
 	out = append(out, stSections.bytes()...)
 
-	// DWARF debug sections (no relocations — the linker resolves DWARF fixups).
+	// DWARF debug sections (no relocations, the linker resolves DWARF fixups).
 	dwAlign := func(n int) {
 		for len(out)%n != 0 {
 			out = append(out, 0)

asm/elf_dwarf.go

@@ -282,7 +282,7 @@ func dwarfBuildFrameSection(img *Image) []byte {
 	// Patch CIE length.
 	le.PutUint32(b[cieStart:], uint32(len(b)-cieStart-4))
 
-	// FDEs (Frame Description Entries) — one per function.
+	// FDEs (Frame Description Entries), one per function.
 	for _, fn := range img.Funcs {
 		fdeStart := len(b)
 		b = append(b, 0, 0, 0, 0)                // length (placeholder)

asm/elf_test.go

@@ -52,7 +52,7 @@ func elfTestImage(t *testing.T) *Image {
 }
 
 // TestAssembleFileExternals checks that a reference to a symbol no GLOBL
-// defines is recorded as an external relocation instead of failing — the
+// defines is recorded as an external relocation instead of failing; the
 // raw image leaves the displacement zero, the object emitters carry it.
 func TestAssembleFileExternals(t *testing.T) {
 	img := elfTestImage(t)

asm/elfarm64.go

@@ -15,8 +15,9 @@ const (
 
 	// AArch64 relocation types (the ELF psABI).
 	rArm64PrelPgHi21   = 275 // R_AARCH64_ADR_PREL_PG_HI21 (ADRP page)
-	rArm64AddAbsLo12NC = 277 // R_AARCH64_ADD_ABS_LO12_NC (ADD/STR/LDR page offset)
+	rArm64AddAbsLo12NC = 277 // R_AARCH64_ADD_ABS_LO12_NC (ADD page offset)
 	rArm64Call26       = 283 // R_AARCH64_CALL26 (BL instruction)
+	rArm64Ldst64Lo12NC = 286 // R_AARCH64_LDST64_ABS_LO12_NC (64-bit LDR/STR page offset)
 )
 
 // ELFAARCH64Object returns the image as an ELF64 relocatable object file for
@@ -81,7 +82,13 @@ func (img *Image) ELFAARCH64Object() ([]byte, error) {
 
 	// Build relocations.  Each SB reference is an ADRP pair:
 	//   ADRP Rd, 0  → R_AARCH64_ADR_PREL_PG_HI21
-	//   ADD/LDR/STR  → R_AARCH64_ADD_ABS_LO12_NC
+	//   ADD         → R_AARCH64_ADD_ABS_LO12_NC
+	//   LDR/STR X   → R_AARCH64_LDST64_ABS_LO12_NC
+	//   BL          → R_AARCH64_CALL26
+	// Addends stay raw: ADR_PREL_PG_HI21 and the ABS_LO12_NC forms resolve
+	// against S+A, and CALL26 branches take the branch instruction's own
+	// place as the PC-relative base, so subtracting the field width (the
+	// amd64 R_PCREL convention) would misplace every branch by 4 bytes.
 	type elfRela struct {
 		off    uint64
 		typ    uint32
@@ -99,6 +106,8 @@ func (img *Image) ELFAARCH64Object() ([]byte, error) {
 			switch {
 			case r.Kind == RelArm64Branch:
 				typ = rArm64Call26
+			case r.Kind == RelArm64LDST64 && r.Off%4 == 4:
+				typ = rArm64Ldst64Lo12NC
 			case r.Kind == RelArm64Addr && r.Off%4 == 4:
 				typ = rArm64AddAbsLo12NC
 			default:
@@ -108,7 +117,7 @@ func (img *Image) ELFAARCH64Object() ([]byte, error) {
 				off:    uint64(fn.Offset + r.Off),
 				typ:    typ,
 				sym:    idx,
-				addend: r.Addend - int64(r.After-r.Off),
+				addend: r.Addend,
 			})
 		}
 	}

asm/elfloong64.go

@@ -16,6 +16,7 @@ const (
 	// LoongArch relocation types (the ELF psABI).
 	rLarchPCALAHI20 = 71 // R_LARCH_PCALA_HI20 (pcalau12i)
 	rLarchPCALALO12 = 72 // R_LARCH_PCALA_LO12 (addi.d/ld/st)
+	rLarchB26       = 66 // R_LARCH_B26 (b/bl, matches the Go linker's mapping)
 )
 
 // ELFLOONG64Object returns the image as an ELF64 relocatable object file for
@@ -95,14 +96,17 @@ func (img *Image) ELFLOONG64Object() ([]byte, error) {
 				return nil, fmt.Errorf("relocation references unknown symbol %q", r.Name)
 			}
 			typ := uint32(rLarchPCALAHI20)
-			if r.Kind == RelLoong64AddrLo {
+			switch r.Kind {
+			case RelLoong64AddrLo:
 				typ = rLarchPCALALO12
+			case RelLoong64Branch:
+				typ = rLarchB26
 			}
 			relas = append(relas, elfRela{
 				off:    uint64(fn.Offset + r.Off),
 				typ:    typ,
 				sym:    idx,
-				addend: r.Addend - int64(r.After-r.Off),
+				addend: r.Addend,
 			})
 		}
 	}

asm/elfloong64_test.go

@@ -198,3 +198,45 @@ TEXT ·nop(SB), NOSPLIT, $0
 		t.Error("function symbol nop not found")
 	}
 }
+
+// TestELFLOONG64BranchRelocation checks that the morestack call and an
+// internal CALL both carry R_LARCH_B26 in the emitted object, matching the
+// Go linker's mapping of its call relocation.
+func TestELFLOONG64BranchRelocation(t *testing.T) {
+	f, errs := parser.Parse("k_loong64.s", "TEXT \u00b7callbig(SB), $8192-0\n\tCALL \u00b7other(SB)\n\tRET\nTEXT \u00b7other(SB), NOSPLIT, $0\n\tRET\n")
+	if len(errs) > 0 {
+		t.Fatalf("parse: %v", errs)
+	}
+	img, err := AssembleFileLOONG64(f)
+	if err != nil {
+		t.Fatalf("AssembleFileLOONG64: %v", err)
+	}
+	obj, err := img.ELFLOONG64Object()
+	if err != nil {
+		t.Fatalf("ELFLOONG64Object: %v", err)
+	}
+	ef, err := elf.NewFile(bytes.NewReader(obj))
+	if err != nil {
+		t.Fatalf("parse emitted object: %v", err)
+	}
+	defer ef.Close()
+	relaSec := ef.Section(".rela.text")
+	if relaSec == nil {
+		t.Fatal("missing .rela.text")
+	}
+	raw, err := relaSec.Data()
+	if err != nil {
+		t.Fatal(err)
+	}
+	// The guard's morestack call plus the body's CALL to other.
+	if len(raw)%24 != 0 || len(raw)/24 != 2 {
+		t.Fatalf(".rela.text has %d bytes, want two 24-byte entries", len(raw))
+	}
+	le := binary.LittleEndian
+	for i := range 2 {
+		info := le.Uint64(raw[i*24+8:])
+		if elf.R_LARCH(info&0xffffffff) != elf.R_LARCH_B26 {
+			t.Errorf("relocation %d type = %v, want R_LARCH_B26", i, elf.R_LARCH(info&0xffffffff))
+		}
+	}
+}

asm/encode.go

@@ -40,10 +40,20 @@ func (e *enc) encode(mnem string, ops []Operand) error {
 		return e.encodeRet()
 	case upper == "NOP":
 		return e.emit(&instr{opcode: []byte{0x90}, modrm: -1, sib: -1})
-	case upper == "CALL":
+	case upper == "CALL" || upper == "JMP":
-		return e.encodeJmpRel(ops, []byte{0xE8})
+		// Through a register or memory: FF /2 (CALL) or FF /4 (JMP).
-	case upper == "JMP":
+		// Anything else is a rel32 against a label resolved by the assembler.
-		return e.encodeJmpRel(ops, []byte{0xE9})
+		if len(ops) == 1 {
+			switch ops[0].(type) {
+			case Reg, Mem:
+				return e.encodeIndirectBranch(upper, ops)
+			}
+		}
+		opcode := []byte{0xE8}
+		if upper == "JMP" {
+			opcode = []byte{0xE9}
+		}
+		return e.encodeJmpRel(ops, opcode)
 	}
 	if cc, ok := condCode(upper); ok {
 		return e.encodeJcc(cc, ops)
@@ -284,7 +294,7 @@ func setRM(i *instr, reg Reg, rm Operand, opSize int) error {
 }
 
 // setRMDigit fills in the ModR/M for an instruction whose reg field is an
-// opcode /digit extension (0–7), which carries none of the register REX rules.
+// opcode /digit extension (0-7), which carries none of the register REX rules.
 func setRMDigit(i *instr, digit int, rm Operand, opSize int) error {
 	return setRMReg(i, digit, false, false, rm, opSize)
 }

asm/encode_test.go

@@ -181,6 +181,39 @@ func TestControl(t *testing.T) {
 	checkOp(t, x86asm.JBE, "JLS", Imm(0))
 }
 
+// TestIndirectControlFlow pins the indirect JMP/CALL forms: FF /4 for JMP and
+// FF /2 for CALL through a register or memory.  A REX appears only for the
+// extended registers, never REX.W: the branch operand size is fixed at 64
+// bits in long mode.
+func TestIndirectControlFlow(t *testing.T) {
+	cases := []struct {
+		name string
+		mnem string
+		ops  []Operand
+		want string
+	}{
+		{"JMP AX", "JMP", []Operand{AX}, "ffe0"},
+		{"CALL AX", "CALL", []Operand{AX}, "ffd0"},
+		{"JMP (BX)", "JMP", []Operand{Ptr(BX, 0, 8)}, "ff23"},
+		{"CALL (BX)", "CALL", []Operand{Ptr(BX, 0, 8)}, "ff13"},
+		{"JMP 8(BX)", "JMP", []Operand{Ptr(BX, 8, 8)}, "ff6308"},
+		{"CALL -16(BX)", "CALL", []Operand{Ptr(BX, -16, 8)}, "ff53f0"},
+		{"JMP R8", "JMP", []Operand{Reg{idx: 8, size: 2}}, "41ffe0"},
+		{"CALL R9", "CALL", []Operand{Reg{idx: 9, size: 2}}, "41ffd1"},
+		{"JMP R15", "JMP", []Operand{Reg{idx: 15, size: 2}}, "41ffe7"},
+	}
+	for _, c := range cases {
+		code, err := Encode(c.mnem, c.ops...)
+		if err != nil {
+			t.Errorf("%s: %v", c.name, err)
+			continue
+		}
+		if got := fmt.Sprintf("%x", code); got != c.want {
+			t.Errorf("%s: got %s, want %s", c.name, got, c.want)
+		}
+	}
+}
+
 // TestSSEMoveGroundTruth checks the legacy (non-VEX) SSE moves byte for byte
 // against the Go assembler.  wantOp is the decoder's name, which differs from
 // the Plan 9 spelling for the octa moves (MOVOU = MOVDQU, MOVO = MOVDQA).
@@ -230,7 +263,7 @@ func TestSSEMoveGroundTruth(t *testing.T) {
 // TestGoFlacScalarTail encodes the scalar tail of an analyze kernel to confirm
 // the encoder handles a realistic instruction sequence.
 func TestGoFlacScalarTail(t *testing.T) {
-	// MOVQ swin_base+0(FP), SI — modelled as MOVQ disp(reg), reg.
+	// MOVQ swin_base+0(FP), SI; modelled as MOVQ disp(reg), reg.
 	checkSyntax(t, "mov rsi, qword ptr [rax+0x10]", "MOVQ", Ptr(AX, 0x10, 8), SI)
 	checkSyntax(t, "lea r9, ptr [rsi+4*rbx]", "LEAQ", Idx(SI, BX, 4, 0, 8), Reg{idx: 9, size: 8})
 	checkSyntax(t, "and r10, -0x8", "ANDQ", Imm(-8), Reg{idx: 10, size: 8})
@@ -421,7 +454,7 @@ func TestSSEShuffleGroundTruth(t *testing.T) {
 }
 
 // TestMOVQXMMGroundTruth pins the SSE2 packed-quadword move encodings:
-// loads and register moves on F3 0F 7E, stores on 66 0F D6 — the forms
+// loads and register moves on F3 0F 7E, stores on 66 0F D6; the forms
 // the GPR-move fallback silently corrupted.
 func TestMOVQXMMGroundTruth(t *testing.T) {
 	cases := []struct {

asm/evex.go

@@ -9,10 +9,10 @@ import (
 )
 
 // This file implements EVEX (AVX-512) instruction encoding: the four-byte
-// EVEX prefix with 5-bit vector register fields (Z0–Z31, X/Y 16–31), the
+// EVEX prefix with 5-bit vector register fields (Z0-Z31, X/Y 16-31), the
 // compressed disp8×N displacement, and the operand shapes the go-flac
 // AVX-512 kernels use plus the common floating-point and conversion set.
-// Masking follows the Go assembler's spelling: an explicit K1–K7 operand
+// Masking follows the Go assembler's spelling: an explicit K1-K7 operand
 // anywhere among the operands (merging) plus a ".Z" mnemonic suffix for
 // zeroing.  K-register operands (mask destinations, KMOVW, KTESTW) are
 // supported too.
@@ -36,7 +36,7 @@ type evexSpec struct {
 // are taken from the Go assembler's opcode tables, which are authoritative
 // for byte-for-byte agreement.
 var evexTable = map[string]evexSpec{
-	// EVEX.128/256/512.66.0F — integer arithmetic / logic, NDS form.
+	// EVEX.128/256/512.66.0F, integer arithmetic / logic, NDS form.
 	"VPADDD":      {1, 0xFE, 0, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VPADDQ":      {1, 0xD4, 1, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VPSUBD":      {1, 0xFA, 0, 1, -1, vexNDS3, [3]int{16, 32, 64}},
@@ -48,25 +48,25 @@ var evexTable = map[string]evexSpec{
 	"VPCMPEQD":    {1, 0x76, 0, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VFMADD231PD": {2, 0xB8, 1, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 
-	// EVEX.128/256/512.66.0F.W1 — packed double arithmetic.
+	// EVEX.128/256/512.66.0F.W1, packed double arithmetic.
 	"VADDPD": {1, 0x58, 1, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VMULPD": {1, 0x59, 1, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VSUBPD": {1, 0x5C, 1, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VDIVPD": {1, 0x5E, 1, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VMINPD": {1, 0x5D, 1, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VMAXPD": {1, 0x5F, 1, 1, -1, vexNDS3, [3]int{16, 32, 64}},
-	// EVEX.128/256/512.0F.W0 — packed single arithmetic.
+	// EVEX.128/256/512.0F.W0, packed single arithmetic.
 	"VADDPS": {1, 0x58, 0, 0, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VMULPS": {1, 0x59, 0, 0, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VSUBPS": {1, 0x5C, 0, 0, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VDIVPS": {1, 0x5E, 0, 0, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VMINPS": {1, 0x5D, 0, 0, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VMAXPS": {1, 0x5F, 0, 0, -1, vexNDS3, [3]int{16, 32, 64}},
-	// EVEX.128/256/512.66.0F.W1 — packed double unpack.
+	// EVEX.128/256/512.66.0F.W1, packed double unpack.
 	"VUNPCKLPD": {1, 0x14, 1, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VUNPCKHPD": {1, 0x15, 1, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 
-	// EVEX.128.F2.0F.W1 — scalar double arithmetic (the packed opcodes with
+	// EVEX.128.F2.0F.W1, scalar double arithmetic (the packed opcodes with
 	// an F2 pp; the EVEX forms exist for masked and zeroing use).  The
 	// memory operand is a single double, so disp8×N = 8.
 	"VADDSD": {1, 0x58, 1, 3, -1, vexNDS3, [3]int{8, 8, 8}},
@@ -76,7 +76,7 @@ var evexTable = map[string]evexSpec{
 	"VMINSD": {1, 0x5D, 1, 3, -1, vexNDS3, [3]int{8, 8, 8}},
 	"VMAXSD": {1, 0x5F, 1, 3, -1, vexNDS3, [3]int{8, 8, 8}},
 
-	// EVEX.128.F3.0F.W0 — scalar single arithmetic (disp8×N = 4).
+	// EVEX.128.F3.0F.W0, scalar single arithmetic (disp8×N = 4).
 	"VADDSS": {1, 0x58, 0, 2, -1, vexNDS3, [3]int{4, 4, 4}},
 	"VSUBSS": {1, 0x5C, 0, 2, -1, vexNDS3, [3]int{4, 4, 4}},
 	"VMULSS": {1, 0x59, 0, 2, -1, vexNDS3, [3]int{4, 4, 4}},
@@ -84,38 +84,38 @@ var evexTable = map[string]evexSpec{
 	"VMINSS": {1, 0x5D, 0, 2, -1, vexNDS3, [3]int{4, 4, 4}},
 	"VMAXSS": {1, 0x5F, 0, 2, -1, vexNDS3, [3]int{4, 4, 4}},
 
-	// EVEX.512.66.0F3A — align (NDS + imm8).
+	// EVEX.512.66.0F3A, align (NDS + imm8).
 	"VALIGND": {3, 0x03, 0, 1, -1, vexNDS3Imm, [3]int{16, 32, 64}},
 
-	// EVEX.128/256/512.66.0F — immediate shift (VPSRAD /4).
+	// EVEX.128/256/512.66.0F, immediate shift (VPSRAD /4).
 	"VPSRAD": {1, 0x72, 0, 1, 4, vexShiftImm, [3]int{16, 32, 64}},
-	// EVEX.128/256/512.66.0F.W1 — variable shift with an XMM count (VPSRAQ;
+	// EVEX.128/256/512.66.0F.W1, variable shift with an XMM count (VPSRAQ;
 	// the W bit distinguishes it from VPSRAD's E2 form).
 	"VPSRAQ": {1, 0xE2, 1, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 
-	// EVEX.128/256/512.F3.0F.W1 — signed qword to packed double (reg=dst,
+	// EVEX.128/256/512.F3.0F.W1, signed qword to packed double (reg=dst,
 	// rm=src, no vvvv).
 	"VCVTQQ2PD": {1, 0xE6, 1, 2, -1, vexRM, [3]int{16, 32, 64}},
-	// EVEX.128/256/512.F2.0F.W1 — duplicate the low double (reg=dst,
+	// EVEX.128/256/512.F2.0F.W1, duplicate the low double (reg=dst,
 	// rm=src, no vvvv): a 128-bit destination reads a single double from
 	// memory (disp8×8), the wider ones read the full operand.
 	"VMOVDDUP": {1, 0x12, 1, 3, -1, vexRM, [3]int{8, 32, 64}},
-	// EVEX.128/256/512.0F.W0 — signed dword to packed single (reg=dst,
+	// EVEX.128/256/512.0F.W0, signed dword to packed single (reg=dst,
-	// rm=src, no vvvv, no mandatory prefix — as in the VEX form).
+	// rm=src, no vvvv, no mandatory prefix, as in the VEX form).
 	"VCVTDQ2PS": {1, 0x5B, 0, 0, -1, vexRM, [3]int{16, 32, 64}},
-	// EVEX.128/256/512.0F.W0 — packed single to packed double: the
+	// EVEX.128/256/512.0F.W0, packed single to packed double: the
 	// destination is twice the source width and sets the length; disp8×N
 	// follows the narrow memory source.  No F3 prefix: the Go assembler
 	// emits this instruction with pp = 00 (Intel's maps would call that
-	// undefined) and gasm reproduces the Go assembler's bytes — its machine
+	// undefined) and gasm reproduces the Go assembler's bytes, its machine
 	// code is the oracle, not the manual.
 	"VCVTPS2PD": {1, 0x5A, 0, 0, -1, vexRM, [3]int{8, 16, 32}},
-	// EVEX.128/256/512.F3.0F.W0 — signed dword to packed double (the EVEX
+	// EVEX.128/256/512.F3.0F.W0, signed dword to packed double (the EVEX
 	// form of the VEX instruction; the destination sets the length, disp8×N
 	// follows the narrow memory source).
 	"VCVTDQ2PD": {1, 0xE6, 0, 2, -1, vexRM, [3]int{8, 16, 32}},
 	// EVEX packed double → dword conversions: the source is the wide
-	// operand and the mnemonic fixes the length — the bare names are
+	// operand and the mnemonic fixes the length, the bare names are
 	// 512-bit only (ZMM source, XMM destination), the X/Y spellings are
 	// EVEX-128/256.  Exactly one slot of n is valid; it names the vector
 	// length (and the disp8×N multiplier) a register or memory source
@@ -127,7 +127,7 @@ var evexTable = map[string]evexSpec{
 	"VCVTTPD2DQX": {1, 0xE6, 1, 1, -1, vexRMSrcLen, [3]int{16, 0, 0}},
 	"VCVTTPD2DQY": {1, 0xE6, 1, 1, -1, vexRMSrcLen, [3]int{0, 32, 0}},
 
-	// EVEX.66.0F3A — ternary logic and lane shuffles (NDS + imm8).
+	// EVEX.66.0F3A, ternary logic and lane shuffles (NDS + imm8).
 	"VPTERNLOGD": {3, 0x25, 0, 1, -1, vexNDS3Imm, [3]int{16, 32, 64}},
 	"VPTERNLOGQ": {3, 0x25, 1, 1, -1, vexNDS3Imm, [3]int{16, 32, 64}},
 	"VSHUFI32X4": {3, 0x43, 0, 1, -1, vexNDS3Imm, [3]int{16, 32, 64}},
@@ -136,11 +136,11 @@ var evexTable = map[string]evexSpec{
 	"VSHUFF64X2": {3, 0x23, 1, 1, -1, vexNDS3Imm, [3]int{16, 32, 64}},
 	"VPALIGNR":   {3, 0x0F, 0, 1, -1, vexNDS3Imm, [3]int{16, 32, 64}},
 
-	// EVEX.66.0F — the EVEX forms of the VEX two-source shuffle.
+	// EVEX.66.0F, the EVEX forms of the VEX two-source shuffle.
 	"VSHUFPD": {1, 0xC6, 1, 1, -1, vexNDS3Imm, [3]int{16, 32, 64}},
 	"VSHUFPS": {1, 0xC6, 0, 1, -1, vexNDS3Imm, [3]int{16, 32, 64}},
 
-	// EVEX.66.0F3A — lane insert ($imm, xsrc, zsrc1, zdst).
+	// EVEX.66.0F3A, lane insert ($imm, xsrc, zsrc1, zdst).
 	"VINSERTF32X4": {3, 0x18, 0, 1, -1, vexNDS3Imm, [3]int{0, 16, 32}},
 	"VINSERTF32X8": {3, 0x1A, 0, 1, -1, vexNDS3Imm, [3]int{0, 0, 32}},
 	"VINSERTF64X2": {3, 0x18, 1, 1, -1, vexNDS3Imm, [3]int{0, 16, 32}},
@@ -150,7 +150,7 @@ var evexTable = map[string]evexSpec{
 	"VINSERTI64X2": {3, 0x38, 1, 1, -1, vexNDS3Imm, [3]int{0, 16, 32}},
 	"VINSERTI64X4": {3, 0x3A, 1, 1, -1, vexNDS3Imm, [3]int{0, 0, 32}},
 
-	// EVEX.66.0F3A — lane extract (reg=source, rm=XMM/YMM destination,
+	// EVEX.66.0F3A, lane extract (reg=source, rm=XMM/YMM destination,
 	// imm8).
 	"VEXTRACTF32X4": {3, 0x19, 0, 1, -1, vexExtract, [3]int{0, 16, 16}},
 	"VEXTRACTF32X8": {3, 0x1B, 0, 1, -1, vexExtract, [3]int{0, 0, 32}},
@@ -159,14 +159,14 @@ var evexTable = map[string]evexSpec{
 	"VEXTRACTI32X8": {3, 0x3B, 0, 1, -1, vexExtract, [3]int{0, 0, 32}},
 	"VEXTRACTI64X2": {3, 0x39, 1, 1, -1, vexExtract, [3]int{0, 16, 16}},
 
-	// EVEX.66.0F — compare with an opmask destination ($imm, src2, src1,
+	// EVEX.66.0F, compare with an opmask destination ($imm, src2, src1,
 	// kdst): NDS3Imm with the K register in the reg field.
 	"VCMPPD": {1, 0xC2, 1, 1, -1, vexNDS3Imm, [3]int{16, 32, 64}},
 	"VCMPPS": {1, 0xC2, 0, 0, -1, vexNDS3Imm, [3]int{16, 32, 64}},
 	"VCMPSD": {1, 0xC2, 1, 3, -1, vexNDS3Imm, [3]int{8, 8, 8}},
 	"VCMPSS": {1, 0xC2, 0, 2, -1, vexNDS3Imm, [3]int{4, 4, 4}},
 
-	// EVEX.66.0F3A — integer compares with an opmask destination, the same
+	// EVEX.66.0F3A, integer compares with an opmask destination, the same
 	// NDS3Imm-with-k-reg shape as the floating-point compares; W selects the
 	// operand width (byte/word vs dword/qword), the opcode the signedness.
 	// The memory form takes a full vector, so disp8×N is 16/32/64.
@@ -179,7 +179,7 @@ var evexTable = map[string]evexSpec{
 	"VPCMPQ":  {3, 0x1F, 1, 1, -1, vexNDS3Imm, [3]int{16, 32, 64}},
 	"VPCMPUQ": {3, 0x1E, 1, 1, -1, vexNDS3Imm, [3]int{16, 32, 64}},
 
-	// EVEX.66.0F38 — permutes (NDS form).
+	// EVEX.66.0F38, permutes (NDS form).
 	"VPERMB":    {2, 0x8D, 0, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VPERMW":    {2, 0x8D, 1, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VPERMI2D":  {2, 0x76, 0, 1, -1, vexNDS3, [3]int{16, 32, 64}},
@@ -188,7 +188,7 @@ var evexTable = map[string]evexSpec{
 	"VPERMT2Q":  {2, 0x7E, 1, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VPERMT2PD": {2, 0x7F, 1, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 
-	// EVEX.66.0F — the wider integer set (NDS form).
+	// EVEX.66.0F, the wider integer set (NDS form).
 	"VPMADDWD":   {1, 0xF5, 0, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VPMULHUW":   {1, 0xE4, 0, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VPMADDUBSW": {2, 0x04, 0, 1, -1, vexNDS3, [3]int{16, 32, 64}},
@@ -199,34 +199,34 @@ var evexTable = map[string]evexSpec{
 	"VPACKSSDW":  {1, 0x6B, 0, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VPACKUSDW":  {2, 0x2B, 0, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 
-	// EVEX.66.0F38 — absolute values and replicating moves (reg=dst,
+	// EVEX.66.0F38, absolute values and replicating moves (reg=dst,
 	// rm=src).
 	"VPABSB": {2, 0x1C, 0, 1, -1, vexRM, [3]int{16, 32, 64}},
 	"VPABSW": {2, 0x1D, 0, 1, -1, vexRM, [3]int{16, 32, 64}},
 	"VPABSD": {2, 0x1E, 0, 1, -1, vexRM, [3]int{16, 32, 64}},
 	"VPABSQ": {2, 0x1F, 1, 1, -1, vexRM, [3]int{16, 32, 64}},
-	// EVEX.F3.0F — replicate even/odd singles.
+	// EVEX.F3.0F, replicate even/odd singles.
 	"VMOVSLDUP": {1, 0x12, 0, 2, -1, vexRM, [3]int{16, 32, 64}},
 	"VMOVSHDUP": {1, 0x16, 0, 2, -1, vexRM, [3]int{16, 32, 64}},
-	// EVEX.66.0F38 — sign/zero-extending moves; the memory source is the
+	// EVEX.66.0F38, sign/zero-extending moves; the memory source is the
 	// narrow half (here byte to word).
 	"VPMOVSXBW": {2, 0x20, 0, 1, -1, vexRM, [3]int{8, 16, 32}},
 	"VPMOVZXBW": {2, 0x30, 0, 1, -1, vexRM, [3]int{8, 16, 32}},
-	// EVEX.66.0F — packed single conversions (reg=dst, rm=src).
+	// EVEX.66.0F, packed single conversions (reg=dst, rm=src).
 	"VCVTPS2DQ":  {1, 0x5B, 0, 1, -1, vexRM, [3]int{16, 32, 64}},
 	"VCVTTPS2DQ": {1, 0x5B, 0, 2, -1, vexRM, [3]int{16, 32, 64}},
-	// EVEX.66.0F38 — broadcast a single/double to all lanes (reg=dst,
+	// EVEX.66.0F38, broadcast a single/double to all lanes (reg=dst,
 	// rm=scalar memory; disp8×N is the element size).
 	"VBROADCASTSS": {2, 0x18, 0, 1, -1, vexRM, [3]int{4, 4, 4}},
 	"VBROADCASTSD": {2, 0x19, 1, 1, -1, vexRM, [3]int{0, 8, 8}},
 
-	// EVEX.66.0F38 — expand loads (rm → vector register destination).
+	// EVEX.66.0F38, expand loads (rm → vector register destination).
 	"VEXPANDPD": {2, 0x88, 1, 1, -1, vexRM, [3]int{8, 8, 8}},
 	"VEXPANDPS": {2, 0x88, 0, 1, -1, vexRM, [3]int{4, 4, 4}},
 	"VPEXPANDD": {2, 0x89, 0, 1, -1, vexRM, [3]int{4, 4, 4}},
 	"VPEXPANDQ": {2, 0x89, 1, 1, -1, vexRM, [3]int{8, 8, 8}},
 
-	// EVEX.66.0F38 — compress stores (vector register source → rm), and the
+	// EVEX.66.0F38, compress stores (vector register source → rm), and the
 	// remaining narrowing stores.
 	"VCOMPRESSPD": {2, 0x8A, 1, 1, -1, vexRMRev, [3]int{8, 8, 8}},
 	"VCOMPRESSPS": {2, 0x8A, 0, 1, -1, vexRMRev, [3]int{4, 4, 4}},
@@ -235,7 +235,7 @@ var evexTable = map[string]evexSpec{
 	"VPMOVWB":     {2, 0x30, 0, 2, -1, vexRMRev, [3]int{8, 16, 32}},
 	"VPMOVQB":     {2, 0x32, 0, 2, -1, vexRMRev, [3]int{2, 4, 8}},
 
-	// EVEX.66.0F — rotates (immediate form: /0 right, /1 left).
+	// EVEX.66.0F, rotates (immediate form: /0 right, /1 left).
 	"VPRORD": {1, 0x72, 0, 1, 0, vexShiftImm, [3]int{16, 32, 64}},
 	"VPRORQ": {1, 0x72, 1, 1, 0, vexShiftImm, [3]int{16, 32, 64}},
 	"VPROLD": {1, 0x72, 0, 1, 1, vexShiftImm, [3]int{16, 32, 64}},
@@ -248,14 +248,14 @@ var evexTable = map[string]evexSpec{
 	"VPSRLQ": {1, 0x73, 1, 1, 2, vexShiftImm, [3]int{16, 32, 64}},
 	"VPSLLQ": {1, 0x73, 1, 1, 6, vexShiftImm, [3]int{16, 32, 64}},
 
-	// EVEX.66.0F38 — floating-point helpers, packed (reg=dst, rm=src).
+	// EVEX.66.0F38, floating-point helpers, packed (reg=dst, rm=src).
 	"VRCP14PD":   {2, 0x4C, 1, 1, -1, vexRM, [3]int{16, 32, 64}},
 	"VRCP14PS":   {2, 0x4C, 0, 1, -1, vexRM, [3]int{16, 32, 64}},
 	"VRSQRT14PD": {2, 0x4E, 1, 1, -1, vexRM, [3]int{16, 32, 64}},
 	"VRSQRT14PS": {2, 0x4E, 0, 1, -1, vexRM, [3]int{16, 32, 64}},
 	"VGETEXPPD":  {2, 0x42, 1, 1, -1, vexRM, [3]int{16, 32, 64}},
 	"VGETEXPPS":  {2, 0x42, 0, 1, -1, vexRM, [3]int{16, 32, 64}},
-	// EVEX.66.0F38 — floating-point helpers, scalar (NDS form: src2 is
+	// EVEX.66.0F38, floating-point helpers, scalar (NDS form: src2 is
 	// rm, src1 is vvvv, the XMM destination is reg).  Like the scalar 0F3A
 	// forms, these take the 66 prefix; W selects double/single.
 	"VRCP14SD":   {2, 0x4D, 1, 1, -1, vexNDS3, [3]int{8, 8, 8}},
@@ -264,13 +264,13 @@ var evexTable = map[string]evexSpec{
 	"VRSQRT14SS": {2, 0x4F, 0, 1, -1, vexNDS3, [3]int{4, 4, 4}},
 	"VGETEXPSD":  {2, 0x43, 1, 1, -1, vexNDS3, [3]int{8, 8, 8}},
 	"VGETEXPSS":  {2, 0x43, 0, 1, -1, vexNDS3, [3]int{4, 4, 4}},
-	// EVEX.66.0F38 — scale by a power of two (NDS form).
+	// EVEX.66.0F38, scale by a power of two (NDS form).
 	"VSCALEFPD": {2, 0x2C, 1, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VSCALEFPS": {2, 0x2C, 0, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VSCALEFSD": {2, 0x2D, 1, 1, -1, vexNDS3, [3]int{8, 8, 8}},
 	"VSCALEFSS": {2, 0x2D, 0, 1, -1, vexNDS3, [3]int{4, 4, 4}},
 
-	// EVEX.66.0F3A — packed round/getmant/reduce ($imm, src, dst: reg=dst,
+	// EVEX.66.0F3A, packed round/getmant/reduce ($imm, src, dst: reg=dst,
 	// rm=src, imm8).
 	"VRNDSCALEPD": {3, 0x09, 1, 1, -1, vexImmRM, [3]int{16, 32, 64}},
 	"VRNDSCALEPS": {3, 0x08, 0, 1, -1, vexImmRM, [3]int{16, 32, 64}},
@@ -278,7 +278,7 @@ var evexTable = map[string]evexSpec{
 	"VGETMANTPS":  {3, 0x26, 0, 1, -1, vexImmRM, [3]int{16, 32, 64}},
 	"VREDUCEPD":   {3, 0x56, 1, 1, -1, vexImmRM, [3]int{16, 32, 64}},
 	"VREDUCEPS":   {3, 0x56, 0, 1, -1, vexImmRM, [3]int{16, 32, 64}},
-	// EVEX.66.0F3A — scalar round/getmant/reduce and fixup/range (NDS +
+	// EVEX.66.0F3A, scalar round/getmant/reduce and fixup/range (NDS +
 	// imm8: $imm, src2, src1, dst).  The scalar 0F3A forms all take the 66
 	// prefix; W selects double/single.
 	"VRNDSCALESD": {3, 0x0B, 1, 1, -1, vexNDS3Imm, [3]int{8, 8, 8}},
@@ -296,7 +296,7 @@ var evexTable = map[string]evexSpec{
 	"VRANGESD":    {3, 0x51, 1, 1, -1, vexNDS3Imm, [3]int{8, 8, 8}},
 	"VRANGESS":    {3, 0x51, 0, 1, -1, vexNDS3Imm, [3]int{4, 4, 4}},
 
-	// EVEX.66.0F3A — floating-point class test ($imm, src, kdst): the
+	// EVEX.66.0F3A, floating-point class test ($imm, src, kdst): the
 	// reg field carries the opmask destination.  The packed forms carry an
 	// explicit length in the mnemonic (X/Y/Z).
 	"VFPCLASSPDX": {3, 0x66, 1, 1, -1, vexImmRM, [3]int{16, 0, 0}},
@@ -308,7 +308,7 @@ var evexTable = map[string]evexSpec{
 	"VFPCLASSSD":  {3, 0x67, 1, 1, -1, vexImmRM, [3]int{8, 0, 0}},
 	"VFPCLASSSS":  {3, 0x67, 0, 1, -1, vexImmRM, [3]int{4, 0, 0}},
 
-	// EVEX — the remaining conversions.  VCVTQQ2PS narrows (the 512-bit
+	// EVEX, the remaining conversions.  VCVTQQ2PS narrows (the 512-bit
 	// source sets the length); the rest follow the destination.
 	"VCVTQQ2PS":  {1, 0x5B, 1, 0, -1, vexRMSrcLen, [3]int{0, 0, 64}},
 	"VCVTPD2QQ":  {1, 0x7B, 1, 1, -1, vexRM, [3]int{16, 32, 64}},
@@ -316,13 +316,13 @@ var evexTable = map[string]evexSpec{
 	"VCVTPS2QQ":  {1, 0x7B, 0, 1, -1, vexRM, [3]int{8, 16, 32}},
 	"VCVTUDQ2PD": {1, 0x7A, 0, 2, -1, vexRM, [3]int{8, 16, 32}},
 	"VCVTUDQ2PS": {1, 0x7A, 0, 0, -1, vexRM, [3]int{8, 16, 32}},
-	// EVEX.66.0F38 — half-precision convert (half-width source).
+	// EVEX.66.0F38, half-precision convert (half-width source).
 	"VCVTPH2PS": {2, 0x13, 0, 1, -1, vexRM, [3]int{8, 16, 32}},
-	// EVEX.66.0F3A — half-precision convert back ($imm, src, dst: reg=src,
+	// EVEX.66.0F3A, half-precision convert back ($imm, src, dst: reg=src,
-	// rm=dst, imm8 — the extract layout).
+	// rm=dst, imm8, the extract layout).
 	"VCVTPS2PH": {3, 0x1D, 0, 1, -1, vexExtract, [3]int{8, 16, 32}},
 
-	// EVEX — unsigned and truncating conversions.  The PD sources are the
+	// EVEX, unsigned and truncating conversions.  The PD sources are the
 	// wide operand (the bare names are 512-bit only, the X/Y spellings fix
 	// the length); the PS/UQQ destinations are wide and follow the
 	// destination.
@@ -349,7 +349,7 @@ var evexTable = map[string]evexSpec{
 	"VCVTQQ2PSX":   {1, 0x5B, 1, 0, -1, vexRMSrcLen, [3]int{16, 0, 0}},
 	"VCVTQQ2PSY":   {1, 0x5B, 1, 0, -1, vexRMSrcLen, [3]int{0, 32, 0}},
 
-	// EVEX.66.0F38 — the remaining sign/zero-extending moves (narrow
+	// EVEX.66.0F38, the remaining sign/zero-extending moves (narrow
 	// source; disp8×N follows its size).
 	"VPMOVSXBD": {2, 0x21, 0, 1, -1, vexRM, [3]int{4, 8, 16}},
 	"VPMOVSXBQ": {2, 0x22, 0, 1, -1, vexRM, [3]int{2, 4, 8}},
@@ -361,7 +361,7 @@ var evexTable = map[string]evexSpec{
 	"VPMOVZXWQ": {2, 0x34, 0, 1, -1, vexRM, [3]int{4, 8, 16}},
 	"VPMOVZXDQ": {2, 0x35, 0, 1, -1, vexRM, [3]int{8, 16, 32}},
 
-	// EVEX.F3.0F38 — the remaining narrowing stores (vector source in reg,
+	// EVEX.F3.0F38, the remaining narrowing stores (vector source in reg,
 	// narrow destination in r/m): signed, unsigned and the D/Q truncations.
 	"VPMOVSDB":  {2, 0x21, 0, 2, -1, vexRMRev, [3]int{4, 8, 16}},
 	"VPMOVSQB":  {2, 0x22, 0, 2, -1, vexRMRev, [3]int{2, 4, 8}},
@@ -378,7 +378,7 @@ var evexTable = map[string]evexSpec{
 	"VPMOVDB":   {2, 0x31, 0, 2, -1, vexRMRev, [3]int{4, 8, 16}},
 	"VPMOVQW":   {2, 0x34, 0, 2, -1, vexRMRev, [3]int{4, 8, 16}},
 
-	// EVEX.F3.0F38 — mask/vector conversions: M2* moves an opmask register
+	// EVEX.F3.0F38, mask/vector conversions: M2* moves an opmask register
 	// into a vector (rm = K source, reg = vector destination), *2M does the
 	// reverse (reg = K destination, rm = vector source, the length follows
 	// the vector).
@@ -391,7 +391,7 @@ var evexTable = map[string]evexSpec{
 	"VPMOVD2M": {2, 0x39, 0, 2, -1, vexRM, [3]int{16, 32, 64}},
 	"VPMOVQ2M": {2, 0x39, 1, 2, -1, vexRM, [3]int{16, 32, 64}},
 
-	// EVEX — scalar conversions between vector and general-purpose
+	// EVEX, scalar conversions between vector and general-purpose
 	// registers.  Vector to GPR (two operands: vec/mem source, GPR
 	// destination, vvvv unused): the signed and truncated pair, and the
 	// unsigned forms (EVEX only).
@@ -421,22 +421,22 @@ var evexTable = map[string]evexSpec{
 	"VCVTUSI2SDQ": {1, 0x7B, 1, 3, -1, vexNDS3, [3]int{8, 8, 8}},
 	"VCVTUSI2SSL": {1, 0x7B, 0, 2, -1, vexNDS3, [3]int{4, 4, 4}},
 	"VCVTUSI2SSQ": {1, 0x7B, 1, 2, -1, vexNDS3, [3]int{8, 8, 8}},
-	// EVEX.128/256/512.66.0F38.W0 — sign-extend dwords to qwords; the memory
+	// EVEX.128/256/512.66.0F38.W0, sign-extend dwords to qwords; the memory
 	// operand is the narrow source, so disp8×N follows its size (8/16/32 for
 	// the xmm/ymm/zmm destination lengths).
 	"VPMOVSXDQ": {2, 0x25, 0, 1, -1, vexRM, [3]int{8, 16, 32}},
 
-	// EVEX.512.66.0F3A.W1 — lane extract (reg=ZMM source, rm=YMM/memory
+	// EVEX.512.66.0F3A.W1, lane extract (reg=ZMM source, rm=YMM/memory
 	// destination, imm8).
 	"VEXTRACTI64X4": {3, 0x3B, 1, 1, -1, vexExtract, [3]int{0, 0, 32}},
 	"VEXTRACTF64X4": {3, 0x1B, 1, 1, -1, vexExtract, [3]int{0, 0, 32}},
 
-	// EVEX.66.0F38 — more integer NDS forms (W distinguishes D/Q).
+	// EVEX.66.0F38, more integer NDS forms (W distinguishes D/Q).
 	"VPMULLD": {2, 0x40, 0, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VPMULLQ": {2, 0x40, 1, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 	"VPERMD":  {2, 0x36, 0, 1, -1, vexNDS3, [3]int{0, 32, 64}},
 
-	// EVEX.128/256/512 — the wider integer set (AVX-512 F/BW): byte/word
+	// EVEX.128/256/512, the wider integer set (AVX-512 F/BW): byte/word
 	// arithmetic, the bitwise ops with D/Q suffixes, min/max, averages and
 	// variable shifts.  All NDS form; W distinguishes element size.
 	"VPADDB":  {1, 0xFC, 0, 1, -1, vexNDS3, [3]int{16, 32, 64}},
@@ -474,21 +474,21 @@ var evexTable = map[string]evexSpec{
 	"VPSRAVQ": {2, 0x46, 1, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 
 	// EVEX forms of instructions that also exist in VEX (selected when a ZMM
-	// or K register, or indices 16–31, demand EVEX).
+	// or K register, or indices 16-31, demand EVEX).
 	"VPSHUFD": {1, 0x70, 0, 1, -1, vexImmRM, [3]int{16, 32, 64}},
 	"VPSHUFB": {2, 0x00, 0, 1, -1, vexNDS3, [3]int{16, 32, 64}},
 
-	// EVEX.66.0F — immediate shift (VPSLLD /6).
+	// EVEX.66.0F, immediate shift (VPSLLD /6).
 	"VPSLLD": {1, 0x72, 0, 1, 6, vexShiftImm, [3]int{16, 32, 64}},
 
-	// EVEX.F3.0F38.W0 — narrowing stores: reg = wide source, rm = narrow
+	// EVEX.F3.0F38.W0, narrowing stores: reg = wide source, rm = narrow
 	// destination (VPMOVDW dword→word, VPMOVQD qword→dword).
 	"VPMOVDW": {2, 0x33, 0, 2, -1, vexRMRev, [3]int{8, 16, 32}},
 	"VPMOVQD": {2, 0x35, 0, 2, -1, vexRMRev, [3]int{8, 16, 32}},
 }
 
 // evexBcastSpec describes an EVEX broadcast (VPBROADCASTD/Q): the opcode
-// depends on the source kind — a GPR source uses opReg, a memory source uses
+// depends on the source kind, a GPR source uses opReg, a memory source uses
 // opMem with a disp8×N of n.
 type evexBcastSpec struct {
 	mapSel int
@@ -499,10 +499,10 @@ type evexBcastSpec struct {
 }
 
 var evexBcastTable = map[string]evexBcastSpec{
-	// EVEX.128/256/512.66.0F38 — broadcast a dword/qword to all lanes.
+	// EVEX.128/256/512.66.0F38, broadcast a dword/qword to all lanes.
 	"VPBROADCASTD": {2, 0x7C, 0x58, 0, 4},
 	"VPBROADCASTQ": {2, 0x7C, 0x59, 1, 8},
-	// EVEX.128/256/512.66.0F38 — broadcast a byte/word (GPR or memory
+	// EVEX.128/256/512.66.0F38, broadcast a byte/word (GPR or memory
 	// source) to all lanes.
 	"VPBROADCASTB": {2, 0x7A, 0x78, 0, 1},
 	"VPBROADCASTW": {2, 0x7B, 0x79, 0, 2},
@@ -521,26 +521,26 @@ type evexMoveSpec struct {
 
 // evexMoveTable maps an upper-case EVEX move mnemonic to its encoding.
 var evexMoveTable = map[string]evexMoveSpec{
-	// EVEX.128/256/512.F3.0F.W0 — unaligned integer move.
+	// EVEX.128/256/512.F3.0F.W0, unaligned integer move.
 	"VMOVDQU32": {1, 2, 0x6F, 0x7F, 0, [3]int{16, 32, 64}},
-	// EVEX.128/256/512.F3.0F.W1 — unaligned qword move.
+	// EVEX.128/256/512.F3.0F.W1, unaligned qword move.
 	"VMOVDQU64": {1, 2, 0x6F, 0x7F, 1, [3]int{16, 32, 64}},
-	// EVEX.128/256/512.F2.0F.W0 — unaligned byte move (byte/word moves use the
+	// EVEX.128/256/512.F2.0F.W0, unaligned byte move (byte/word moves use the
 	// F2 prefix, dword/qword moves F3; the element size only changes the tuple
 	// semantics).
 	"VMOVDQU8": {1, 3, 0x6F, 0x7F, 0, [3]int{16, 32, 64}},
-	// EVEX.128/256/512.F2.0F.W1 — unaligned word move (shares the qword
+	// EVEX.128/256/512.F2.0F.W1, unaligned word move (shares the qword
 	// encoding).
 	"VMOVDQU16": {1, 3, 0x6F, 0x7F, 1, [3]int{16, 32, 64}},
-	// EVEX.128/256/512.66.0F.W1 — unaligned packed double move.
+	// EVEX.128/256/512.66.0F.W1, unaligned packed double move.
 	"VMOVUPD": {1, 1, 0x10, 0x11, 1, [3]int{16, 32, 64}},
-	// EVEX.128/256/512 — aligned packed moves.
+	// EVEX.128/256/512, aligned packed moves.
 	"VMOVAPS": {1, 0, 0x28, 0x29, 0, [3]int{16, 32, 64}},
 	"VMOVAPD": {1, 1, 0x28, 0x29, 1, [3]int{16, 32, 64}},
-	// EVEX.128/256/512.66.0F — aligned integer moves.
+	// EVEX.128/256/512.66.0F, aligned integer moves.
 	"VMOVDQA32": {1, 1, 0x6F, 0x7F, 0, [3]int{16, 32, 64}},
 	"VMOVDQA64": {1, 1, 0x6F, 0x7F, 1, [3]int{16, 32, 64}},
-	// EVEX.128.F3.0F.W0 — scalar single move, memory operands (the
+	// EVEX.128.F3.0F.W0, scalar single move, memory operands (the
 	// three-operand register form is not supported).
 	"VMOVSS": {1, 2, 0x10, 0x11, 0, [3]int{4, 4, 4}},
 }
@@ -559,7 +559,7 @@ func isEvex(mnemUpper string) bool {
 
 // evexRequired reports whether the operands force the EVEX encoding of a
 // mnemonic that also has a VEX form: ZMM and K registers do, and so do
-// register indices 16–31, which only EVEX can represent (X16–Y31 exist
+// register indices 16-31, which only EVEX can represent (X16-Y31 exist
 // solely under AVX-512).
 func evexRequired(upper string, ops []Operand) bool {
 	_, inVex := vexTable[upper]
@@ -578,7 +578,7 @@ func evexRequired(upper string, ops []Operand) bool {
 // evexSuffix carries the EVEX mnemonic suffixes the Go assembler accepts:
 // zeroing (.Z), a rounding mode (.RN_SAE, .RD_SAE, .RU_SAE, .RZ_SAE),
 // suppress-all-exceptions (.SAE) and memory broadcast (.BCST).  Masking is
-// not a suffix — Go writes it as an explicit K operand.
+// not a suffix, Go writes it as an explicit K operand.
 type evexSuffix struct {
 	zeroing  bool
 	sae      bool
@@ -668,7 +668,7 @@ var evexRound = map[string]bool{
 }
 
 // evexBcstN maps an instruction accepting .BCST to the broadcast element
-// size — the disp8×N multiplier for its memory operand.
+// size, the disp8×N multiplier for its memory operand.
 var evexBcstN = map[string]int{
 	"VADDPD": 8, "VSUBPD": 8, "VMULPD": 8, "VDIVPD": 8,
 	"VMINPD": 8, "VMAXPD": 8,
@@ -689,7 +689,7 @@ var evexBcstN = map[string]int{
 	"VCVTTPD2QQ": 8, "VCVTTPS2QQ": 4, "VCVTUQQ2PD": 8, "VCVTUQQ2PS": 8,
 }
 
-// splitMask extracts an explicit mask register (K1–K7) from the operand list,
+// splitMask extracts an explicit mask register (K1-K7) from the operand list,
 // returning the remaining operands and the mask index.  K0 is not a usable
 // mask (aaa = 0 means "no mask"), matching the assembler.
 func splitMask(ops []Operand) ([]Operand, int, error) {
@@ -712,7 +712,7 @@ func splitMask(ops []Operand) ([]Operand, int, error) {
 }
 
 // encodeEvex encodes an EVEX instruction with operands in Plan 9 order.  The
-// mask, when present, is an explicit K1–K7 operand anywhere among the
+// mask, when present, is an explicit K1-K7 operand anywhere among the
 // operands; the mnemonic suffix carries zeroing, rounding/SAE and
 // broadcast.
 func (e *enc) encodeEvex(mnemUpper string, ops []Operand, sfx evexSuffix) error {
@@ -1042,7 +1042,7 @@ func (e *enc) encodeEvexMove(mnem string, ms evexMoveSpec, ops []Operand, mask i
 }
 
 // encodeEvexRMSrcLen encodes a length-narrowing conversion: OP src, dst with
-// the destination always XMM and the length fixed by the mnemonic — the
+// the destination always XMM and the length fixed by the mnemonic, the
 // single valid slot of spec.n names the vector length (and the disp8×N
 // multiplier) a register or memory source encodes.
 func (e *enc) encodeEvexRMSrcLen(spec evexSpec, ops []Operand, mask int, sfx evexSuffix) error {
@@ -1061,7 +1061,7 @@ func (e *enc) encodeEvexRMSrcLen(spec evexSpec, ops []Operand, mask int, sfx eve
 	return e.emitEvexFields(spec, ll, dstReg.idx, -1, src, mask, sfx)
 }
 
-// soleLen returns the vector-length index of the single valid slot of n —
+// soleLen returns the vector-length index of the single valid slot of n
 // the length a length-fixed mnemonic (the EVEX conversion spellings) encodes
 // regardless of its operands.
 func soleLen(n [3]int) (int, error) {
@@ -1131,8 +1131,8 @@ func (e *enc) encodeEvexBcast(bs evexBcastSpec, ops []Operand, mask int, sfx eve
 
 // emitEvexFields emits the EVEX prefix, opcode, ModR/M, SIB and displacement
 // (disp8×N compressed) for the given precomputed fields.  regIdx is the
-// unextended reg-field register index, or a /digit (0–7); vvvvIdx is the
+// unextended reg-field register index, or a /digit (0-7); vvvvIdx is the
-// vvvv register index, or -1 when unused.  mask (K1–K7, 0 = unmasked) and
+// vvvv register index, or -1 when unused.  mask (K1-K7, 0 = unmasked) and
 // zeroing fill the aaa and z bits of the P2 byte.
 func (e *enc) emitEvexFields(spec evexSpec, ll, regIdx, vvvvIdx int, rm Operand, mask int, sfx evexSuffix) error {
 	if ll > 2 {
@@ -1324,7 +1324,7 @@ func isScatter(upper string) bool {
 }
 
 // vsibLen validates a VSIB memory operand (the index must be a vector
-// register) and returns it with the vector length the index selects — the
+// register) and returns it with the vector length the index selects, the
 // EVEX L'L field follows the index register, not the data register.
 func vsibLen(op Operand, what string) (Mem, int, error) {
 	m, ok := op.(Mem)
@@ -1383,7 +1383,7 @@ func (e *enc) encodeGather(upper string, gs gatherSpec, ops []Operand, sfx evexS
 	return e.emitVexFields(spec, dst.vecLenBit(), dst.idx&7, rBit, 15-maskReg.idx, vsib)
 }
 
-// encodeScatter encodes a scatter (EVEX only): OP src, K, vsib — reg = src,
+// encodeScatter encodes a scatter (EVEX only): OP src, K, vsib, reg = src,
 // rm = the VSIB memory operand, the K mask in aaa and L following the VSIB
 // index.
 func (e *enc) encodeScatter(upper string, ss gatherSpec, ops []Operand, sfx evexSuffix) error {
@@ -1411,15 +1411,15 @@ func (e *enc) encodeScatter(upper string, ss gatherSpec, ops []Operand, sfx evex
 
 // evexKOperand lists the instructions whose K register is a genuine operand
 // (the source or destination of a mask/vector conversion) rather than a
-// mask modifier — the M2 and 2M conversions.  They take no masking.
+// mask modifier, the M2 and 2M conversions.  They take no masking.
 var evexKOperand = map[string]bool{
 	"VPMOVM2B": true, "VPMOVM2W": true, "VPMOVM2D": true, "VPMOVM2Q": true,
 	"VPMOVB2M": true, "VPMOVW2M": true, "VPMOVD2M": true, "VPMOVQ2M": true,
 }
 
 // kmovSpec describes a KMOV width: the opcode depends on the operand
-// direction — kk (k/mem → K is 90, k → k uses the same), kmem (K → mem),
+// direction, kk (k/mem → K is 90, k → k uses the same), kmem (K → mem),
-// gprk (GPR/mem → K), kgpr (K → GPR) — and the GPR forms carry a mandatory
+// gprk (GPR/mem → K), kgpr (K → GPR), and the GPR forms carry a mandatory
 // prefix and W for the wider widths.
 type kmovSpec struct {
 	kk, kmem, gprk, kgpr byte

asm/evex_test.go

@@ -16,7 +16,7 @@ import (
 // kernels use: NDS arithmetic, immediate and variable shifts, shuffles with
 // an immediate, lane extracts, narrowing stores, broadcasts from a GPR or
 // memory, mask destinations, mask moves, disp8×N compression and the 5-bit
-// register fields (X/Y 16–31, Z 0–31).
+// register fields (X/Y 16-31, Z 0-31).
 func TestEvexGroundTruth(t *testing.T) {
 	cases := []struct {
 		name string
@@ -58,7 +58,7 @@ func TestEvexGroundTruth(t *testing.T) {
 		{"VMOVDQU32 16(SI)(R15*4),Z4", "VMOVDQU32", []Operand{Idx(SI, vreg(t, "R15"), 4, 16, 64), vreg(t, "Z4")}, "62b17e486fa4be10000000"},
 		{"VMOVDQU32 Z0,4(SI)(AX*1)", "VMOVDQU32", []Operand{vreg(t, "Z0"), Idx(SI, AX, 1, 4, 64)}, "62f17e487f840604000000"},
 		{"VMOVDQU32 Z3,(DI)(R15*4)", "VMOVDQU32", []Operand{vreg(t, "Z3"), Idx(DI, vreg(t, "R15"), 4, 0, 64)}, "62b17e487f1cbf"},
-		// VMOVDQU64 — the W1 qword variant.
+		// VMOVDQU64; the W1 qword variant.
 		{"VMOVDQU64 (SI)(R15*4),Z3", "VMOVDQU64", []Operand{Idx(SI, vreg(t, "R15"), 4, 0, 64), vreg(t, "Z3")}, "62b1fe486f1cbe"},
 		{"VMOVDQU64 Z0,4(SI)(AX*1)", "VMOVDQU64", []Operand{vreg(t, "Z0"), Idx(SI, AX, 1, 4, 64)}, "62f1fe487f840604000000"},
 		{"VMOVDQU64 Z1,Z2", "VMOVDQU64", []Operand{vreg(t, "Z1"), vreg(t, "Z2")}, "62f1fe487fca"},
@@ -77,7 +77,7 @@ func TestEvexGroundTruth(t *testing.T) {
 		{"VPSHUFB Z1,Z2,Z3", "VPSHUFB", []Operand{vreg(t, "Z1"), vreg(t, "Z2"), vreg(t, "Z3")}, "62f26d4800d9"},
 		{"VMOVDQU8 Z1,Z2", "VMOVDQU8", []Operand{vreg(t, "Z1"), vreg(t, "Z2")}, "62f17f487fca"},
 		{"VMOVDQU16 Z1,Z2", "VMOVDQU16", []Operand{vreg(t, "Z1"), vreg(t, "Z2")}, "62f1ff487fca"},
-		// Indices 16–31: rm[4] rides in X̄ for register operands.
+		// Indices 16-31: rm[4] rides in X̄ for register operands.
 		{"VPSHUFD $1,X16,X17", "VPSHUFD", []Operand{Imm(1), vreg(t, "X16"), vreg(t, "X17")}, "62a17d0870c801"},
 		{"VMOVUPD (DI),Z14", "VMOVUPD", []Operand{Ptr(DI, 0, 64), vreg(t, "Z14")}, "6271fd481037"},
 		{"VMOVUPD 64(DI),Z14", "VMOVUPD", []Operand{Ptr(DI, 64, 64), vreg(t, "Z14")}, "6271fd48107701"},
@@ -96,7 +96,7 @@ func TestEvexGroundTruth(t *testing.T) {
 		{"VPBROADCASTD 4(SI),Z10", "VPBROADCASTD", []Operand{Ptr(SI, 4, 4), vreg(t, "Z10")}, "62727d48585601"},
 		{"VPBROADCASTQ R8,X31", "VPBROADCASTQ", []Operand{vreg(t, "R8"), vreg(t, "X31")}, "6242fd087cf8"},
 		{"VPBROADCASTQ AX,Z9", "VPBROADCASTQ", []Operand{AX, vreg(t, "Z9")}, "6272fd487cc8"},
-		// Register indices 16–31 exist only in EVEX encodings.
+		// Register indices 16-31 exist only in EVEX encodings.
 		{"VPBROADCASTD AX,Y30", "VPBROADCASTD", []Operand{AX, vreg(t, "Y30")}, "62627d287cf0"},
 		// Packed double arithmetic / unpack (EVEX forms carry W=1).
 		{"VSUBPD Z1,Z2,Z3", "VSUBPD", []Operand{vreg(t, "Z1"), vreg(t, "Z2"), vreg(t, "Z3")}, "62f1ed485cd9"},
@@ -107,7 +107,7 @@ func TestEvexGroundTruth(t *testing.T) {
 		{"VUNPCKHPD Z1,Z2,Z3", "VUNPCKHPD", []Operand{vreg(t, "Z1"), vreg(t, "Z2"), vreg(t, "Z3")}, "62f1ed4815d9"},
 		{"VSUBPD 64(AX),Z1,Z2", "VSUBPD", []Operand{Ptr(AX, 64, 64), vreg(t, "Z1"), vreg(t, "Z2")}, "62f1f5485c5001"},
 		{"VSUBPD Z17,Z18,Z19", "VSUBPD", []Operand{vreg(t, "Z17"), vreg(t, "Z18"), vreg(t, "Z19")}, "62a1ed405cd9"},
-		// VMOVDDUP — duplicate the low double; disp8×N = 64 at 512 bits, and
+		// VMOVDDUP; duplicate the low double; disp8×N = 64 at 512 bits, and
 		// X16/X17 force EVEX (the mod=11 rm[4] extension rides in X̄).
 		{"VMOVDDUP Z1,Z2", "VMOVDDUP", []Operand{vreg(t, "Z1"), vreg(t, "Z2")}, "62f1ff4812d1"},
 		{"VMOVDDUP 64(AX),Z1", "VMOVDDUP", []Operand{Ptr(AX, 64, 64), vreg(t, "Z1")}, "62f1ff48124801"},
@@ -150,7 +150,7 @@ func TestEvexGroundTruth(t *testing.T) {
 	}
 }
 
-// TestEvexMasking checks the AVX-512 mask operand (K1–K7, placed freely among
+// TestEvexMasking checks the AVX-512 mask operand (K1-K7, placed freely among
 // the operands) and the .Z zeroing suffix, byte for byte against the Go
 // assembler.
 func TestEvexMasking(t *testing.T) {
@@ -241,11 +241,11 @@ func TestEvexMasking(t *testing.T) {
 	}
 }
 
-// TestEvexExtendedGroundTruth covers the wider EVEX/AVX-512 set — ternary
+// TestEvexExtendedGroundTruth covers the wider EVEX/AVX-512 set; ternary
 // logic, lane shuffles/inserts/extracts, compares with a K destination,
 // permutes, the wider integer families, expand/compress, broadcasts,
 // rotates and word shifts, the opmask instructions, the EVEX suffixes
-// (rounding/SAE/broadcast) and the aligned/scalar moves — byte for byte
+// (rounding/SAE/broadcast) and the aligned/scalar moves; byte for byte
 // against the Go assembler.
 func TestEvexExtendedGroundTruth(t *testing.T) {
 	mem64 := func(base Reg) Operand { return Ptr(base, 0, 64) }
@@ -275,7 +275,7 @@ func TestEvexExtendedGroundTruth(t *testing.T) {
 		{"VMULPD.RZ_SAE.Z", "VMULPD.RZ_SAE.Z", []Operand{vreg(t, "Z1"), vreg(t, "Z2"), vreg(t, "K1"), vreg(t, "Z3")}, "62f1edf959d9"},
 		{"VMAXPD.SAE", "VMAXPD.SAE", []Operand{vreg(t, "Z1"), vreg(t, "Z2"), vreg(t, "Z3")}, "62f1ed585fd9"},
 		{"VADDPD.BCST", "VADDPD.BCST", []Operand{mem64(AX), vreg(t, "Z1"), vreg(t, "Z2")}, "62f1f5585810"},
-		// Packed single arithmetic (same opcodes, no mandatory prefix) —
+		// Packed single arithmetic (same opcodes, no mandatory prefix);
 		// ZMM, YMM and XMM widths, rounding and broadcast.
 		{"VADDPS", "VADDPS", []Operand{vreg(t, "Z1"), vreg(t, "Z2"), vreg(t, "Z3")}, "62f16c4858d9"},
 		{"VMULPS", "VMULPS", []Operand{vreg(t, "Y1"), vreg(t, "Y2"), vreg(t, "Y3")}, "c5ec59d9"},
@@ -399,8 +399,8 @@ func TestEvexExtendedGroundTruth(t *testing.T) {
 }
 
 // TestEvexHelperGroundTruth covers the floating-point helper and conversion
-// tail of the EVEX set — reciprocals, rsqrt, getexp/getmant, scalef,
+// tail of the EVEX set; reciprocals, rsqrt, getexp/getmant, scalef,
-// rndscale, reduce, fixupimm, range, fpclass, the remaining conversions —
+// rndscale, reduce, fixupimm, range, fpclass, the remaining conversions;
 // plus gather/scatter with VSIB addressing, byte for byte against the Go
 // assembler.
 func TestEvexHelperGroundTruth(t *testing.T) {
@@ -502,9 +502,9 @@ func TestEvexHelperGroundTruth(t *testing.T) {
 }
 
 // TestEvexGprGroundTruth covers the scalar conversions between vector and
-// general-purpose registers — the signed and truncated VCVT{,T}S{D,S}2SI
+// general-purpose registers; the signed and truncated VCVT{,T}S{D,S}2SI
 // forms (VEX and EVEX), the unsigned EVEX-only forms, and the GPR-to-vector
-// VCVTSI2*/VCVTUSI2* forms with the preserved vector source in vvvv — byte
+// VCVTSI2*/VCVTUSI2* forms with the preserved vector source in vvvv; byte
 // for byte against the Go assembler, including memory sources and extended
 // GPRs.
 func TestEvexGprGroundTruth(t *testing.T) {

asm/goobj.go

@@ -14,8 +14,8 @@ import (
 	"sync"
 )
 
-// This file emits GOOBJ — the Go toolchain's object format, which cmd/link
+// This file emits GOOBJ, the Go toolchain's object format, which cmd/link
-// consumes directly — so gasm-assembled functions drop into a go build
+// consumes directly, so gasm-assembled functions drop into a go build
 // without the Go assembler.  The layout follows cmd/internal/goobj: a
 // toolchain preamble ("go object ...\n!\n"), the go120ld header with its
 // block offsets, a string table, symbol definitions, the relocation /
@@ -94,10 +94,12 @@ const (
 )
 
 // Relocation types (cmd/internal/objabi).
-// R_PCREL and R_ADDR are stable across Go versions.
+// R_ADDR, R_CALL, R_PCREL and R_TLS_LE are stable across Go versions.
 const (
-	relocPCRel = 14 // R_PCREL
 	relocAddr  = 1  // R_ADDR
+	relocCall  = 7  // R_CALL
+	relocPCRel = 14 // R_PCREL
+	relocTLSLE = 15 // R_TLS_LE
 )
 
 // relocDWTXTADDRU4 returns the R_DWTXTADDR_U4 relocation type for the
@@ -142,8 +144,28 @@ func isGo127OrLater() bool {
 const (
 	pkgIdxNone    = 0x7fffffff
 	pkgIdxSelf    = 0x7ffffffb
+	pkgIdxBuiltin = 0x7ffffffc
 )
 
+// goobjBuiltinMorestackNoctxt is the index of runtime.morestack_noctxt in
+// cmd/internal/goobj/builtinlist.go of the toolchain the object targets
+// (246 since Go 1.25; the list is append-only).
+const goobjBuiltinMorestackNoctxt = 246
+
+// goobjBuiltinMorestack is the builtin reference the toolchain emits for the
+// stack-guard call.
+var goobjBuiltinMorestack = "runtime\u00b7morestack_noctxt"
+
+// isCallReloc reports whether k is one of the per-arch call relocations a
+// direct branch to a TEXT symbol carries.
+func isCallReloc(k RelocKind) bool {
+	switch k {
+	case RelCall, RelRISCVJal, RelArm64Branch, RelLoong64Branch:
+		return true
+	}
+	return false
+}
+
 const goobjMagic = "\x00go120ld"
 
 // goSym is one symbol definition under construction.
@@ -178,14 +200,24 @@ type dwarfRelocSet struct {
 // does with its -p flag).  srcPath names the source file recorded in the
 // object's file table and line tables.  The toolchain's object preamble is
 // captured from the installed go tool asm, so the output links with the
-// toolchain it was produced on — exactly like a real assembly object.
+// toolchain it was produced on, exactly like a real assembly object.
 func (img *Image) GOObject(pkgPath, srcPath string) ([]byte, error) {
 	pre, err := toolchainObjectPreamble()
 	if err != nil {
 		return nil, err
 	}
-	// amd64: MinLC 1, R_PCREL for the code relocations.
+	// amd64: MinLC 1, R_PCREL for displacements, R_CALL for calls and
-	return img.emitGOObject(pkgPath, srcPath, pre, 1, func(Reloc) (uint16, uint8) { return relocPCRel, 4 })
+	// R_TLS_LE for the stack-guard TLS load.
+	return img.emitGOObject(pkgPath, srcPath, pre, 1, func(r Reloc) (uint16, uint8) {
+		switch r.Kind {
+		case RelCall:
+			return relocCall, 4
+		case RelTLSLE:
+			return relocTLSLE, 4
+		default:
+			return relocPCRel, 4
+		}
+	})
 }
 
 // emitGOObject assembles the GOOBJ payload for any architecture.  pre is
@@ -198,7 +230,7 @@ func (img *Image) emitGOObject(pkgPath, srcPath string, pre []byte, minLC int, r
 		return nil, fmt.Errorf("GOOBJ emission requires a package path (-p)")
 	}
 
-	// The non-package definitions first — the DWARF symbols reference the
+	// The non-package definitions first, the DWARF symbols reference the
 	// functions by these indices: per function the four pc-value tables
 	// and the function itself, as cmd/asm lays them out.
 	type npSym struct {
@@ -247,7 +279,7 @@ func (img *Image) emitGOObject(pkgPath, srcPath string, pre []byte, minLC int, r
 			// their relocations cover whole AUIPC/pcalau12i pairs, so
 			// zeroing r.Off would erase the opcode/register bits the linker
 			// preserves when it patches only the immediate.
-			if r.Kind != RelPCRel32 {
+			if r.Kind != RelPCRel32 && r.Kind != RelCall {
 				continue
 			}
 			if r.Off >= 0 && r.Off+4 <= len(code) {
@@ -320,6 +352,13 @@ func (img *Image) emitGOObject(pkgPath, srcPath string, pre []byte, minLC int, r
 		)
 	}
 
+	// Index the non-package TEXT definitions by short name for the internal
+	// call references.
+	textNpIdx := map[string]int{}
+	for i, fn := range img.Funcs {
+		textNpIdx[fn.Name] = fnNpIdx[i]
+	}
+
 	// Resolve external symbol references (cross-package).  Build the
 	// package index table and determine each external symbol's SymIdx
 	// by reading the target package's export data.
@@ -327,12 +366,22 @@ func (img *Image) emitGOObject(pkgPath, srcPath string, pre []byte, minLC int, r
 	var extPkgIdx map[string]int
 	var extSymIdx map[string]int
 	if len(img.Externals) > 0 {
+		// The morestack call is a builtin reference, not a resolved external.
+		var need []string
+		for _, n := range img.Externals {
+			if n == goobjBuiltinMorestack {
+				continue
+			}
+			need = append(need, n)
+		}
+		if len(need) > 0 {
 			var err error
-		extPkgTable, extPkgIdx, extSymIdx, err = resolveExternalSymbols(img.Externals)
+			extPkgTable, extPkgIdx, extSymIdx, err = resolveExternalSymbols(need)
 			if err != nil {
 				return nil, fmt.Errorf("GOOBJ emission: resolving external symbols: %w", err)
 			}
 		}
+	}
 
 	// Relocations, per defined symbol in definition order (package defs,
 	// then non-package defs).
@@ -342,6 +391,31 @@ func (img *Image) emitGOObject(pkgPath, srcPath string, pre []byte, minLC int, r
 		si := len(defs) + fnNpIdx[i]
 		for _, r := range fn.Relocs {
 			typ, size := relocField(r)
+			if r.Kind == RelTLSLE {
+				// The TLS load has no symbol: {0, 0} is the nil ref.
+				var rec [23]byte
+				binary.LittleEndian.PutUint32(rec[0:], uint32(int32(r.Off)))
+				rec[4] = size
+				binary.LittleEndian.PutUint16(rec[5:], typ)
+				binary.LittleEndian.PutUint64(rec[7:], uint64(r.Addend))
+				binary.LittleEndian.PutUint32(rec[15:], 0)
+				binary.LittleEndian.PutUint32(rec[19:], 0)
+				symRelocs[si] = append(symRelocs[si], rec[:]...)
+				continue
+			}
+			if r.External && r.Name == goobjBuiltinMorestack {
+				// The stack-guard morestack call uses the toolchain's
+				// builtin reference.
+				var rec [23]byte
+				binary.LittleEndian.PutUint32(rec[0:], uint32(int32(r.Off)))
+				rec[4] = size
+				binary.LittleEndian.PutUint16(rec[5:], typ)
+				binary.LittleEndian.PutUint64(rec[7:], uint64(r.Addend))
+				binary.LittleEndian.PutUint32(rec[15:], pkgIdxBuiltin)
+				binary.LittleEndian.PutUint32(rec[19:], goobjBuiltinMorestackNoctxt)
+				symRelocs[si] = append(symRelocs[si], rec[:]...)
+				continue
+			}
 			if r.External {
 				// Split package-qualified name: "runtime·morestack" → runtime, morestack.
 				pkg, name := splitQualified(r.Name)
@@ -366,16 +440,24 @@ func (img *Image) emitGOObject(pkgPath, srcPath string, pre []byte, minLC int, r
 				symRelocs[si] = append(symRelocs[si], rec[:]...)
 				continue
 			}
+			pkg := uint32(pkgIdxSelf)
 			di, ok := defIdx[r.Name]
 			if !ok {
+				// A call to a TEXT function of the same file references the
+				// non-package definition table.
+				ni, isText := textNpIdx[r.Name]
+				if !isText || !isCallReloc(r.Kind) {
 					return nil, fmt.Errorf("GOOBJ emission: reference to unknown symbol %q", r.Name)
 				}
+				pkg = pkgIdxNone
+				di = ni
+			}
 			var rec [23]byte
 			binary.LittleEndian.PutUint32(rec[0:], uint32(int32(r.Off)))
 			rec[4] = size // field width
 			binary.LittleEndian.PutUint16(rec[5:], typ)
 			binary.LittleEndian.PutUint64(rec[7:], uint64(r.Addend))
-			binary.LittleEndian.PutUint32(rec[15:], pkgIdxSelf)
+			binary.LittleEndian.PutUint32(rec[15:], pkg)
 			binary.LittleEndian.PutUint32(rec[19:], uint32(di))
 			symRelocs[si] = append(symRelocs[si], rec[:]...)
 		}

asm/goobj_resolve.go

@@ -84,7 +84,7 @@ func sortedPkgRefs(refs map[string][]string) []pkgRef {
 	for pkg, syms := range refs {
 		pkgs = append(pkgs, pkgRef{pkg, syms})
 	}
-	// Simple insertion sort — the list is tiny (usually 1–3 packages).
+	// Simple insertion sort, the list is tiny (usually 1-3 packages).
 	for i := 1; i < len(pkgs); i++ {
 		for j := i; j > 0 && pkgs[j-1].path > pkgs[j].path; j-- {
 			pkgs[j-1], pkgs[j] = pkgs[j], pkgs[j-1]

asm/goobj_test.go

@@ -158,8 +158,8 @@ DATA mask<>+8(SB)/8, $0x800f0e0d0c0b0a09
 		t.Errorf("funcinfo bytes %x", fi)
 	}
 
-	// The pc-value tables of addq (non-package indices 0–3, so global
+	// The pc-value tables of addq (non-package indices 0-3, so global
-	// indices 7–10): pcsp a flat zero over the whole function, pcinline a
+	// indices 7-10): pcsp a flat zero over the whole function, pcinline a
 	// flat -1, both with the pc delta in MinLC (1) units.
 	pcsp := data[le.Uint32(didx[4*7:]):]
 	if got := pcsp[:3]; !bytes.Equal(got, []byte{0x02, 19, 0x00}) {
@@ -294,7 +294,7 @@ TEXT ·framed(SB), NOSPLIT, $8-0
 	}
 	for i := range wantPCs {
 		if pcs[i] != wantPCs[i] || vals[i] != wantVals[i] {
-			t.Errorf("pcsp[%d] = (%d,%d), want (%d,%d) — all: %v %v", i, pcs[i], vals[i], wantPCs[i], wantVals[i], pcs, vals)
+			t.Errorf("pcsp[%d] = (%d,%d), want (%d,%d); all: %v %v", i, pcs[i], vals[i], wantPCs[i], wantVals[i], pcs, vals)
 		}
 	}
 	// The last two steps unwind the epilogue to zero.
@@ -333,7 +333,7 @@ TEXT ·useext(SB), NOSPLIT, $0-8
 
 // TestGOObjectLinkAndRun is the end-to-end check: assemble the test
 // functions to a GOOBJ, swap it into a go build in place of the toolchain's
-// assembly object, link, and run — the output must match the baseline
+// assembly object, link, and run; the output must match the baseline
 // binary the Go assembler produced.  Skipped when no Go toolchain is
 // available.
 func TestGOObjectLinkAndRun(t *testing.T) {

asm/goobjarm64.go

@@ -13,28 +13,33 @@ import (
 )
 
 // GOObjectAARCH64 emits a GOOBJ object file for AArch64.  The layout is
-// the shared one in goobj.go — the toolchain preamble, the go120ld header
+// the shared one in goobj.go, the toolchain preamble, the go120ld header
 // with its block offsets, the string table, the symbol definitions and the
-// reloc/aux/data index arrays — with the arm64 preamble, the MinLC of 4
+// reloc/aux/data index arrays, with the arm64 preamble, the MinLC of 4
-// for the pc-value deltas, and R_ADDRARM64 relocation types for the
+// for the pc-value deltas, and the arm64 relocation types for the ADRP
-// ADRP+ADD/LDR/STR address pairs.
+// pairs and BL calls.
 func (img *Image) GOObjectAARCH64(pkgPath, srcPath string) ([]byte, error) {
 	pre, err := toolchainObjectPreambleAARCH64()
 	if err != nil {
 		return nil, err
 	}
 	return img.emitGOObject(pkgPath, srcPath, pre, 4, func(r Reloc) (uint16, uint8) {
-		if r.Kind == RelArm64Branch {
+		switch r.Kind {
+		case RelArm64Branch:
 			return relocArm64Branch, 4
-		}
+		case RelArm64LDST64:
+			return relocArm64LDST64, 4
+		default:
 			return relocArm64Addr, 4
+		}
 	})
 }
 
 // arm64 relocation types (cmd/internal/objabi).
 const (
-	relocArm64Addr   = 3 // R_ADDRARM64 — ADRP+ADD/LDR/STR pair
+	relocArm64Addr   = 3  // R_ADDRARM64, ADRP+ADD pair
-	relocArm64Branch = 9 // R_CALLARM64 — BL instruction
+	relocArm64Branch = 9  // R_CALLARM64, BL instruction
+	relocArm64LDST64 = 40 // R_ARM64_PCREL_LDST64, ADRP+LDR/STR pair
 )
 
 // toolchainObjectPreambleAARCH64 returns the "go object ...\n!\n" header

asm/goobjloong64.go

@@ -13,9 +13,9 @@ import (
 )
 
 // GOObjectLOONG64 emits a GOOBJ object file for LoongArch.  The layout is
-// the shared one in goobj.go — the toolchain preamble, the go120ld header
+// the shared one in goobj.go, the toolchain preamble, the go120ld header
 // with its block offsets, the string table, the symbol definitions and the
-// reloc/aux/data index arrays — with the loong64 preamble, the MinLC of 4
+// reloc/aux/data index arrays, with the loong64 preamble, the MinLC of 4
 // for the pc-value deltas, and R_LOONG64_ADDR_HI/LO relocation types for
 // the pcalau12i+addi.d address pairs.
 func (img *Image) GOObjectLOONG64(pkgPath, srcPath string) ([]byte, error) {
@@ -25,11 +25,16 @@ func (img *Image) GOObjectLOONG64(pkgPath, srcPath string) ([]byte, error) {
 	}
 	return img.emitGOObject(pkgPath, srcPath, pre, 4, func(r Reloc) (uint16, uint8) {
 		// A pcalau12i+addi.d pair: the high part carries
-		// R_LOONG64_ADDR_HI, the low part R_LOONG64_ADDR_LO.
+		// R_LOONG64_ADDR_HI, the low part R_LOONG64_ADDR_LO; the guard's
-		if r.Kind == RelLoong64AddrLo {
+		// morestack call carries R_CALLLOONG64.
+		switch {
+		case r.Kind == RelLoong64AddrLo:
 			return relocLoong64AddrLo, 4
-		}
+		case r.Kind == RelLoong64Branch:
+			return relocCallLoong64, 4
+		default:
 			return relocLoong64AddrHi, 4
+		}
 	})
 }
 
@@ -39,6 +44,7 @@ func (img *Image) GOObjectLOONG64(pkgPath, srcPath string) ([]byte, error) {
 const (
 	relocLoong64AddrHi = 77 // R_LOONG64_ADDR_HI
 	relocLoong64AddrLo = 78 // R_LOONG64_ADDR_LO
+	relocCallLoong64   = 84 // R_CALLLOONG64
 )
 
 // toolchainObjectPreambleLOONG64 returns the "go object ...\n!\n" header

asm/goobjriscv.go

@@ -13,9 +13,9 @@ import (
 )
 
 // GOObjectRISCV emits a GOOBJ object file for RISC-V.  The layout is the
-// shared one in goobj.go — the toolchain preamble, the go120ld header with
+// shared one in goobj.go, the toolchain preamble, the go120ld header with
 // its block offsets, the string table, the symbol definitions and the
-// reloc/aux/data index arrays — with the RISC-V preamble, the MinLC of 2 for
+// reloc/aux/data index arrays, with the RISC-V preamble, the MinLC of 2 for
 // the pc-value deltas, and the single R_RISCV_PCREL_ITYPE/STYPE relocation
 // per AUIPC pair, matching `go tool asm`'s model (each pair is one 8-byte
 // relocation, not the ELF HI20/LO12 pair).

asm/guard_test.go

@@ -0,0 +1,283 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+package asm
+
+import (
+	"bytes"
+	"encoding/hex"
+	"testing"
+
+	"sourcedock.dev/petrbalvin/gasm-devkit/ast"
+	"sourcedock.dev/petrbalvin/gasm-devkit/parser"
+)
+
+// The expected bytes are pinned from `go tool asm` output (Go 1.27, amd64,
+// verified with go tool objdump): the stack-split guard classes, the morestack
+// block and the auto-NOSPLIT leaf behaviour.
+func TestStackGuardBytes(t *testing.T) {
+	for _, tt := range []struct {
+		name string
+		src  string
+		want string
+	}{
+		{"leafsmall", "TEXT \u00b7leafsmall(SB), $16-0\n\tRET\n",
+			"554889e54883ec104883c4105dc3"},
+		{"leafmed", "TEXT \u00b7leafmed(SB), $256-0\n\tRET\n",
+			"644c8b3425000000004c8da42478ffffff4d3b66107614554889e54881ec000100004881c4000100005dc3e800000000ebce"},
+		{"leafbig", "TEXT \u00b7leafbig(SB), $8192-0\n\tRET\n",
+			"644c8b3425000000004989e44981ec881f0000721a4d3b66107614554889e54881ec002000004881c4002000005dc3e800000000ebca"},
+		{"callsmall", "TEXT \u00b7callsmall(SB), $16-0\n\tCALL \u00b7other(SB)\n\tRET\nTEXT \u00b7other(SB), NOSPLIT, $0\n\tRET\n",
+			"644c8b342500000000493b66107613554889e54883ec10e8000000004883c4105dc3e800000000ebd7"},
+		{"nosplit", "TEXT \u00b7nosplit(SB), NOSPLIT, $16-0\n\tRET\n",
+			"554889e54883ec104883c4105dc3"},
+	} {
+		f, errs := parser.Parse("g_amd64.s", tt.src)
+		if len(errs) > 0 {
+			t.Fatalf("%s: parse: %v", tt.name, errs)
+		}
+		img, err := AssembleFile(f)
+		if err != nil {
+			t.Fatalf("%s: assemble: %v", tt.name, err)
+		}
+		fn := img.Funcs[0]
+		// The toolchain's object leaves every relocation field zero for the
+		// linker, while the gasm image resolves file-internal references, so
+		// the comparison masks the patch sites the way verify's ground truth
+		// does.
+		code := append([]byte(nil), img.Code[fn.Offset:fn.Offset+fn.Size]...)
+		for _, r := range fn.Relocs {
+			for j := r.Off; j < r.Off+4 && j < len(code); j++ {
+				code[j] = 0
+			}
+		}
+		got := hex.EncodeToString(code)
+		if got != tt.want {
+			t.Errorf("%s:\n  got  %s\n  want %s", tt.name, got, tt.want)
+		}
+	}
+}
+
+// TestStackGuardRelocs checks the guard's patch sites: the TLS slot and the
+// morestack call.
+func TestStackGuardRelocs(t *testing.T) {
+	f, errs := parser.Parse("g_amd64.s", "TEXT \u00b7f(SB), $256-0\n\tRET\n")
+	if len(errs) > 0 {
+		t.Fatalf("parse: %v", errs)
+	}
+	img, err := AssembleFile(f)
+	if err != nil {
+		t.Fatalf("assemble: %v", err)
+	}
+	relocs := img.Funcs[0].Relocs
+	if len(relocs) != 2 {
+		t.Fatalf("relocs = %d, want 2", len(relocs))
+	}
+	tls, call := relocs[0], relocs[1]
+	if tls.Kind != RelTLSLE || tls.Off != 5 || tls.Name != "" || tls.External {
+		t.Errorf("tls reloc = %+v, want RelTLSLE at 5 with no symbol", tls)
+	}
+	if call.Kind != RelCall || call.Name != "runtime\u00b7morestack_noctxt" || !call.External {
+		t.Errorf("call reloc = %+v, want RelCall to runtime.morestack_noctxt", call)
+	}
+}
+
+// TestStackGuardGOObj emissions succeed with the guard's TLS and builtin
+// references in play.
+func TestStackGuardGOObj(t *testing.T) {
+	f, errs := parser.Parse("g_amd64.s", "TEXT \u00b7f(SB), $256-0\n\tCALL \u00b7helper(SB)\n\tRET\nTEXT \u00b7helper(SB), NOSPLIT, $0\n\tRET\n")
+	if len(errs) > 0 {
+		t.Fatalf("parse: %v", errs)
+	}
+	img, err := AssembleFile(f)
+	if err != nil {
+		t.Fatalf("assemble: %v", err)
+	}
+	obj, err := img.GOObject("testpkg", "g_amd64.s")
+	if err != nil {
+		t.Fatalf("GOObject: %v", err)
+	}
+	if !bytes.Contains(obj, []byte("go120ld")) {
+		t.Fatal("object lacks the GOOBJ magic")
+	}
+}
+
+// The arm64 stack-split guard, pinned from `go tool asm` (Go 1.27, arm64):
+// the guard classes, the auto-NOSPLIT leaf behaviour and the morestack
+// block.  Relocation fields are masked: the toolchain's object leaves them
+// zero for the linker, the gasm image resolves file-internal references.
+func TestStackGuardBytesARM64(t *testing.T) {
+	for _, tt := range []struct {
+		name string
+		src  string
+		want string
+	}{
+		{"leafsmall", "TEXT \u00b7leafsmall(SB), $16-0\n\tRET\n",
+			"fe0f1ef8fd831ff8fd2300d1fd630091ff830091c0035fd6"},
+		{"leafmed", "TEXT \u00b7leafmed(SB), $256-0\n\tRET\n",
+			"900b40f9f14302d13f0210eb09010054f44304d19dfa3fa99f020091fd2300d1fd230491ff430491c0035fd6e3031eaa00000000f3ffff17"},
+		{"leafbig", "TEXT \u00b7leafbig(SB), $8192-0\n\tRET\n",
+			"900b40f91bf283d2f1633beba30100543f0210eb690100541b0284d2f4633bcb9dfa3fa99f020091fd2300d11b0184d2fd633b8b1b0284d2ff633b8bc0035fd6e3031eaa00000000eeffff17"},
+		{"callsmall", "TEXT \u00b7callsmall(SB), $16-0\n\tCALL \u00b7other(SB)\n\tRET\nTEXT \u00b7other(SB), NOSPLIT, $0\n\tRET\n",
+			"900b40f9ff6330eb09010054fe0f1ef8fd831ff8fd2300d100000000fd835ff8fe0742f8c0035fd6e3031eaa00000000f4ffff17"},
+		{"nosplit", "TEXT \u00b7nosplit(SB), NOSPLIT, $16-0\n\tRET\n",
+			"fe0f1ef8fd831ff8fd2300d1fd630091ff830091c0035fd6"},
+	} {
+		f, errs := parser.Parse("g_arm64.s", tt.src)
+		if len(errs) > 0 {
+			t.Fatalf("%s: parse: %v", tt.name, errs)
+		}
+		img, err := AssembleFileARM64(f)
+		if err != nil {
+			t.Fatalf("%s: assemble: %v", tt.name, err)
+		}
+		fn := img.Funcs[0]
+		code := append([]byte(nil), img.Code[fn.Offset:fn.Offset+fn.Size]...)
+		for _, r := range fn.Relocs {
+			for j := r.Off; j < r.Off+4 && j < len(code); j++ {
+				code[j] = 0
+			}
+		}
+		got := hex.EncodeToString(code)
+		if got != tt.want {
+			t.Errorf("%s:\n  got  %s\n  want %s", tt.name, got, tt.want)
+		}
+	}
+}
+
+// The riscv64 stack-split guard, pinned from `go tool asm` (Go 1.27,
+// riscv64): the morestack call sits between the guard and the body, and the
+// guard branches forward over it.  Relocation fields are masked.
+func TestStackGuardBytesRISCV64(t *testing.T) {
+	for _, tt := range []struct {
+		name string
+		src  string
+		want string
+	}{
+		{"leafsmall", "TEXT \u00b7leafsmall(SB), $16-0\n\tRET\n",
+			"03b30d0163662300000000006ff05fff233411fe211106e08260610167800000"},
+		{"leafmed", "TEXT \u00b7leafmed(SB), $256-0\n\tRET\n",
+			"03b30d01930381f763667300000000006ff01fff233c11ee130181ef06e082601301811067800000"},
+		{"leafbig", "TEXT \u00b7leafbig(SB), $8192-0\n\tRET\n",
+			"03b30d0189639b8383f863697100f97f9b8f8f07b303f10163667300000000006ff01ffef97f8a9f23bc1ffef97fe13f7e9106e08260896fa12f7e9167800000"},
+		{"frameless", "TEXT \u00b7frameless(SB), $0-0\n\tCALL \u00b7other(SB)\n\tRET\nTEXT \u00b7other(SB), NOSPLIT, $0\n\tRET\n",
+			"03b30d0163662300000000006ff05fff233c11fe611106e0000000008260210167800000"},
+		{"nosplit", "TEXT \u00b7nosplit(SB), NOSPLIT, $16-0\n\tRET\n",
+			"233411fe211106e08260610167800000"},
+	} {
+		f, errs := parser.Parse("g_riscv64.s", tt.src)
+		if len(errs) > 0 {
+			t.Fatalf("%s: parse: %v", tt.name, errs)
+		}
+		img, err := AssembleFileRISCV(f)
+		if err != nil {
+			t.Fatalf("%s: assemble: %v", tt.name, err)
+		}
+		fn := img.Funcs[0]
+		code := append([]byte(nil), img.Code[fn.Offset:fn.Offset+fn.Size]...)
+		for _, r := range fn.Relocs {
+			for j := r.Off; j < r.Off+4 && j < len(code); j++ {
+				code[j] = 0
+			}
+		}
+		got := hex.EncodeToString(code)
+		if got != tt.want {
+			t.Errorf("%s:\n  got  %s\n  want %s", tt.name, got, tt.want)
+		}
+	}
+}
+
+// The loong64 stack-split guard, pinned from `go tool asm` (Go 1.27,
+// loong64): every guard class (including the medium class with the
+// materialised constant and the big class with the ORI-less constants), the
+// auto-NOSPLIT leaf behaviour, the large-frame R30 prologue/epilogue forms
+// and the morestack block.  Relocation fields are masked.
+func TestStackGuardBytesLOONG64(t *testing.T) {
+	for _, tt := range []struct {
+		name string
+		src  string
+		want string
+	}{
+		{"leafsmall", "TEXT \u00b7leafsmall(SB), $16-0\n\tRET\n",
+			"61a0ff2963a0ff026100c0296360c0022000004c"},
+		{"leafmed", "TEXT \u00b7leafmed(SB), $256-0\n\tRET\n",
+			"d442c02878e0fd0294e21200801a004061e0fb2963e0fb026100c0296320c4022000004c3f00150000000000ffd7ff53"},
+		{"nosplit", "TEXT \u00b7nosplit(SB), NOSPLIT, $16-0\n\tRET\n",
+			"61a0ff2963a0ff026100c0296360c0022000004c"},
+		// The LR store leaves the 12-bit store-offset range while the SP
+		// adjust immediate still fits, and the epilogue adjusts through a
+		// single ORI.
+		{"fit2048", "TEXT \u00b7fit2048(SB), $2040-0\n\tRET\n",
+			"d442c0287800e20294e21200802600401e000014de8f1000c103e0296300e0026100c0291e00a00363f810002000004c3f00150000000000ffcbff53"},
+		// Medium class at the materialisation boundary (off = 2048 still
+		// immediate, 2049+ goes through R30).
+		{"med2048off", "TEXT \u00b7med2048off(SB), $2168-0\n\tRET\n",
+			"d442c0287800e00294e21200802e0040feffff15de8f1000c103de29feffff15de039e0363f810006100c0291e00a20363f810002000004c3f00150000000000ffc3ff53"},
+		{"medmat", "TEXT \u00b7medmat(SB), $2176-0\n\tRET\n",
+			"d442c028feffff15dee39f0378f8100094e21200802e0040feffff15de8f1000c1e3dd29feffff15dee39d0363f810006100c0291e20a20363f810002000004c3f00150000000000ffbbff53"},
+		// Big class with the rounding-split store and the floor-split adjust.
+		{"leafbig", "TEXT \u00b7leafbig(SB), $8192-0\n\tRET\n",
+			"d442c0283e000014de23be0378f8120000470044deffff15dee3810378f8100094e2120080320040deffff15de8f1000c1e3ff29beffff15dee3bf0363f810006100c0295e000014de23800363f810002000004c3f00150000000000ffa7ff53"},
+		// Zero low 12 bits drop the ORI from the store, the adjust and the
+		// epilogue materialisation.
+		{"bigzero", "TEXT \u00b7bigzero(SB), $4088-0\n\tRET\n",
+			"d442c028feffff15de03820378f8100094e21200802a0040feffff15de8f1000c103c029feffff1563f810006100c0293e00001463f810002000004c3f00150000000000ffbfff53"},
+		// Big class whose first constant has a zero high part: a single ORI.
+		{"big3976", "TEXT \u00b7big3976(SB), $4096-0\n\tRET\n",
+			"d442c0281e20be0378f8120000470044feffff15dee3810378f8100094e2120080320040feffff15de8f1000c1e3ff29deffff15dee3bf0363f810006100c0293e000014de23800363f810002000004c3f00150000000000ffabff53"},
+		// Big class at a multiple of 4096: both guard constants lose their
+		// ORI word.
+		{"giantlo0", "TEXT \u00b7giantlo0(SB), $4216-0\n\tRET\n",
+			"d442c0283e00001478f8120000430044feffff1578f8100094e2120080320040feffff15de8f1000c103fe29deffff15de03be0363f810006100c0293e000014de03820363f810002000004c3f00150000000000ffafff53"},
+		// Non-leaf big frame: the body call plus the LR restore epilogue.
+		{"callbig", "TEXT \u00b7callbig(SB), $8192-0\n\tCALL \u00b7other(SB)\n\tRET\nTEXT \u00b7other(SB), NOSPLIT, $0\n\tRET\n",
+			"d442c0283e000014de23be0378f81200004f0044deffff15dee3810378f8100094e21200803a0040deffff15de8f1000c1e3ff29beffff15dee3bf0363f810006100c029000000006100c0285e000014de23800363f810002000004c3f00150000000000ff9fff53"},
+	} {
+		f, errs := parser.Parse("g_loong64.s", tt.src)
+		if len(errs) > 0 {
+			t.Fatalf("%s: parse: %v", tt.name, errs)
+		}
+		img, err := AssembleFileLOONG64(f)
+		if err != nil {
+			t.Fatalf("%s: assemble: %v", tt.name, err)
+		}
+		fn := img.Funcs[0]
+		code := append([]byte(nil), img.Code[fn.Offset:fn.Offset+fn.Size]...)
+		for _, r := range fn.Relocs {
+			for j := r.Off; j < r.Off+4 && j < len(code); j++ {
+				code[j] = 0
+			}
+		}
+		got := hex.EncodeToString(code)
+		if got != tt.want {
+			t.Errorf("%s:\n  got  %s\n  want %s", tt.name, got, tt.want)
+		}
+	}
+}
+
+// TestStackGuardGOObjInternalCall checks that GOOBJ emission succeeds when a
+// guarded function calls a TEXT symbol of the same file, for every arch's
+// call relocation kind.
+func TestStackGuardGOObjInternalCall(t *testing.T) {
+	for _, tt := range []struct {
+		src      string
+		assemble func(*ast.File) (*Image, error)
+	}{
+		{"g_amd64.s", AssembleFile},
+		{"g_arm64.s", AssembleFileARM64},
+		{"g_riscv64.s", AssembleFileRISCV},
+		{"g_loong64.s", AssembleFileLOONG64},
+	} {
+		f, errs := parser.Parse(tt.src, "TEXT \u00b7callsmall(SB), $16-0\n\tCALL \u00b7other(SB)\n\tRET\nTEXT \u00b7other(SB), NOSPLIT, $0\n\tRET\n")
+		if len(errs) > 0 {
+			t.Fatalf("%s: parse: %v", tt.src, errs)
+		}
+		img, err := tt.assemble(f)
+		if err != nil {
+			t.Fatalf("%s: assemble: %v", tt.src, err)
+		}
+		if _, err := img.GOObject("testpkg", tt.src); err != nil {
+			t.Errorf("%s: GOObject: %v", tt.src, err)
+		}
+	}
+}

asm/instrs.go

@@ -21,7 +21,7 @@ var aluOp = map[string]struct {
 }
 
 // unaryOp maps INC/DEC/NEG/NOT to their /digit and base opcode.  INC/DEC use
-// the 0xFE/0xFF group (the short 0x40–0x4F forms are REX prefixes in 64-bit
+// the 0xFE/0xFF group (the short 0x40-0x4F forms are REX prefixes in 64-bit
 // mode); NEG/NOT use the 0xF6/0xF7 group.
 var unaryOp = map[string]struct {
 	digit int
@@ -33,7 +33,7 @@ var unaryOp = map[string]struct {
 	"NEG": {3, 0xF7},
 }
 
-// shiftOp maps SHL/SHR/SAR to their /digit in the 0xC0/0xC1/0xD0–0xD3 group.
+// shiftOp maps SHL/SHR/SAR to their /digit in the 0xC0/0xC1/0xD0-0xD3 group.
 var shiftOp = map[string]int{
 	"SHL": 4,
 	"SHR": 5,
@@ -50,7 +50,7 @@ func (e *enc) encodeMov(ops []Operand, size int) error {
 
 	// Integer scalar XMM moves: MOVQ with an XMM operand is the SSE2
 	// packed-quadword move, NOT a GPR move: mem→xmm encodes as F3 0F 7E
-	// (reg = dst, no REX.W — the Go assembler's form), xmm→mem as
+	// (reg = dst, no REX.W, the Go assembler's form), xmm→mem as
 	// 66 0F D6 (rm = xmm).  Register forms against a GPR use the MOVD
 	// opcodes with REX.W instead: 66 REX.W 0F 6E (gpr→xmm) and
 	// 66 REX.W 0F 7E (xmm→gpr); the memory opcodes with a register r/m
@@ -103,7 +103,7 @@ func (e *enc) encodeMov(ops []Operand, size int) error {
 	switch src := src.(type) {
 	case Reg:
 		if dstIsReg {
-			// MOV r/m, r: 0x88/0x89, reg=src, rm=dst — the form the Go
+			// MOV r/m, r: 0x88/0x89, reg=src, rm=dst, the form the Go
 			// assembler emits for register-to-register moves.
 			i := newInstr(size, []byte{movRM(size)})
 			if err := setRM(i, src, dst, size); err != nil {
@@ -147,7 +147,7 @@ func (e *enc) encodeMov(ops []Operand, size int) error {
 			// a signed int32, choosing per sign:
 			//   v >= 0: B8+rd imm32 without REX.W (zero-extended by the
 			//           hardware, REX.B still emitted for R8-R15);
-			//   v <  0: REX.W C7 /0 imm32 (sign-extended — the plain B8+rd
+			//   v <  0: REX.W C7 /0 imm32 (sign-extended, the plain B8+rd
 			//           form would zero-extend and corrupt the value).
 			// Out-of-range immediates keep the B8+rd imm64 form.
 			if size == 8 && v >= 0 && v <= (1<<31)-1 {
@@ -226,8 +226,8 @@ func (e *enc) encodeALU(op struct {
 		return e.encodeALUImm(op.digit, dst, int64(imm), size)
 	}
 
-	// CMP accepts the immediate in the second position too — CMPL CX, $31 is
+	// CMP accepts the immediate in the second position too, CMPL CX, $31 is
-	// the form the Go assembler itself accepts — and encodes it identically
+	// the form the Go assembler itself accepts, and encodes it identically
 	// (CMP r/m, imm sets the flags as first − second).  No other ALU op takes
 	// an immediate destination.
 	if imm, ok := dst.(Imm); ok {
@@ -313,7 +313,7 @@ func (e *enc) encodeALUImm(digit int, dst Operand, imm int64, size int) error {
 		i.imm = []byte{byte(int8(imm))}
 		return e.emit(i)
 	}
-	// 0x81 /digit, imm16/imm32 — or the Go assembler's accumulator short
+	// 0x81 /digit, imm16/imm32, or the Go assembler's accumulator short
 	// form (opcode+5, no ModR/M) when the destination is AX/AL, which it
 	// prefers over the generic form exactly here.
 	if r, ok := dst.(Reg); ok && r.idx == 0 {
@@ -339,7 +339,7 @@ func (e *enc) encodeTest(ops []Operand, size int) error {
 	}
 	src, dst := ops[0], ops[1]
 	if imm, ok := src.(Imm); ok {
-		// TEST r/m, imm: 0xF6 (8-bit) / 0xF7 /0 — but the Go assembler
+		// TEST r/m, imm: 0xF6 (8-bit) / 0xF7 /0, but the Go assembler
 		// always uses the accumulator forms (A8/A9, no ModR/M) when the
 		// register operand is AL/AX, whatever the immediate's width.
 		if r, ok := dst.(Reg); ok && r.idx == 0 {
@@ -575,6 +575,24 @@ func (e *enc) encodeJmpRel(ops []Operand, opcode []byte) error {
 	return e.emit(&instr{opcode: opcode, modrm: -1, sib: -1, imm: le32(int64(imm))})
 }
 
+// encodeIndirectBranch encodes JMP/CALL through a register or memory operand:
+// FF /4 for JMP, FF /2 for CALL.  The operand size is fixed at 64 bits in
+// 64-bit mode, so no REX.W is emitted; a REX appears only for R8-R15 bases.
+func (e *enc) encodeIndirectBranch(mnem string, ops []Operand) error {
+	if len(ops) != 1 {
+		return fmt.Errorf("%s expects 1 operand, got %d", mnem, len(ops))
+	}
+	digit := 4 // JMP r/m64
+	if mnem == "CALL" {
+		digit = 2 // CALL r/m64
+	}
+	i := &instr{opcode: []byte{0xFF}, modrm: -1, sib: -1}
+	if err := setRMDigit(i, digit, ops[0], 8); err != nil {
+		return err
+	}
+	return e.emit(i)
+}
+
 // condCode maps a Plan 9 conditional-jump mnemonic to its x86 condition code.
 func condCode(upper string) (int, bool) {
 	if len(upper) < 2 || upper[0] != 'J' || upper == "JMP" {
@@ -678,7 +696,7 @@ func (e *enc) encodeCmov(upper string, ops []Operand) error {
 }
 
 // encodeSet encodes a conditional byte set: SET + condition (SETNE, SETEQ, …),
-// always a byte write — 0F 90+cc /0 into a register or memory operand.
+// always a byte write, 0F 90+cc /0 into a register or memory operand.
 func (e *enc) encodeSet(upper string, ops []Operand) error {
 	if len(ops) != 1 {
 		return fmt.Errorf("SETcc expects 1 operand, got %d", len(ops))
@@ -711,8 +729,8 @@ var countOp = map[string]struct {
 	"POPCNT": {0xB8, 0xF3},
 }
 
-// encodeCount encodes the bit-scan and bit-count family — BSF (0F BC),
+// encodeCount encodes the bit-scan and bit-count family, BSF (0F BC),
-// BSR (0F BD), TZCNT (F3 0F BC), LZCNT (F3 0F BD) and POPCNT (F3 0F B8) —
+// BSR (0F BD), TZCNT (F3 0F BC), LZCNT (F3 0F BD) and POPCNT (F3 0F B8)
 // with reg = dst and rm = src.  The size suffix selects the operand width
 // (BSFQ, TZCNTL, …).  Note BSF/BSR leave the destination undefined when the
 // source is zero (unlike their F3-prefixed counterparts); callers must
@@ -801,8 +819,8 @@ type sseMove struct {
 }
 
 var sseMoveTable = map[string]sseMove{
-	"MOVOU":  {0xF3, 0x6F, 0x7F}, // MOVDQU — unaligned octa
+	"MOVOU":  {0xF3, 0x6F, 0x7F}, // MOVDQU, unaligned octa
-	"MOVO":   {0x66, 0x6F, 0x7F}, // MOVDQA — aligned octa
+	"MOVO":   {0x66, 0x6F, 0x7F}, // MOVDQA, aligned octa
 	"MOVUPS": {0x00, 0x10, 0x11}, // unaligned packed single
 	"MOVAPS": {0x00, 0x28, 0x29}, // aligned packed single
 	"MOVUPD": {0x66, 0x10, 0x11}, // unaligned packed double

asm/integration_test.go

@@ -19,8 +19,8 @@ import (
 	"sourcedock.dev/petrbalvin/gasm-devkit/parser"
 )
 
-// TestAssembleGoFlacAVX2Kernel assembles the whole production AVX2 kernel —
+// TestAssembleGoFlacAVX2Kernel assembles the whole production AVX2 kernel;
-// all functions plus the file-local mask24 constant — and checks that every
+// all functions plus the file-local mask24 constant; and checks that every
 // static-symbol load resolves to the right bytes in the image.
 func TestAssembleGoFlacAVX2Kernel(t *testing.T) {
 	path := "../../go-libraries/go-flac/avx2_amd64.s"
@@ -81,7 +81,7 @@ func TestAssembleGoFlacAVX2Kernel(t *testing.T) {
 }
 
 // TestAssembleGoFlacAVX512Kernel assembles the whole production AVX-512
-// kernel — all functions plus the file-global idx16 constant — and checks
+// kernel, all functions plus the file-global idx16 constant, and checks
 // that the static-symbol load resolves to the right bytes in the image.
 func TestAssembleGoFlacAVX512Kernel(t *testing.T) {
 	path := "../../go-libraries/go-flac/avx512_amd64.s"

asm/l64_goobj_test.go

@@ -94,9 +94,9 @@ DATA ·table<>+0(SB)/8, $0x1122334455667788
 	}
 
 	// The debug_line program: LNE_set_address (the R_ADDR relocation
-	// carries the function address), then one row per line change — the
+	// carries the function address), then one row per line change; the
 	// TEXT is on line 4 (a leading blank line precedes the include), the
-	// instructions on lines 5–9 — an advance to the 20-byte end and an
+	// instructions on lines 5-9; an advance to the 20-byte end and an
 	// end-of-sequence.
 	linesOff := le.Uint32(dataIdx[4*2:])
 	lines := dataBlk[linesOff : linesOff+21]

asm/link.go

@@ -6,6 +6,7 @@ package asm
 import (
 	"fmt"
 	"sort"
+	"strconv"
 
 	"sourcedock.dev/petrbalvin/gasm-devkit/ast"
 )
@@ -15,7 +16,7 @@ import (
 // file-local static symbols are encoded RIP-relative and resolved within the
 // image, so the raw bytes are self-consistent and executable at any base
 // address; references to external symbols are recorded as relocations
-// (Funcs[i].Relocs, Externals) and left unresolved — the object-file
+// (Funcs[i].Relocs, Externals) and left unresolved, the object-file
 // emitters turn them into linker relocations.
 type Image struct {
 	Code      []byte         // concatenated function bodies
@@ -90,14 +91,18 @@ type RelocKind int
 
 const (
 	RelPCRel32         RelocKind = iota // 32-bit PC-relative (amd64)
+	RelCall                             // R_CALL: CALL to a function symbol (amd64)
+	RelTLSLE                            // R_TLS_LE: local-exec TLS load, no symbol (amd64 guard)
 	RelRISCVPCRELIType                  // R_RISCV_PCREL_ITYPE (AUIPC + I-type pair)
 	RelRISCVPCRELSType                  // R_RISCV_PCREL_STYPE (AUIPC + S-type pair)
 	RelRISCVJal                         // R_RISCV_JAL (J-type call)
 	RelPCRelAbs                         // 32-bit absolute (R_RISCV_32)
 	RelLoong64AddrHi                    // R_LOONG64_ADDR_HI (pcalau12i)
 	RelLoong64AddrLo                    // R_LOONG64_ADDR_LO (addi.d/ld/st)
-	RelArm64Addr                        // R_ADDRARM64 (ADRP + ADD/LDR/STR pair)
+	RelArm64Addr                        // R_ADDRARM64 (ADRP + ADD pair)
 	RelArm64Branch                      // R_CALLARM64 (BL instruction)
+	RelArm64LDST64                      // R_ARM64_PCREL_LDST64 (ADRP + 64-bit LDR/STR pair)
+	RelLoong64Branch                    // R_CALLLOONG64 (BL instruction)
 )
 
 type Reloc struct {
@@ -132,7 +137,7 @@ func (img *Image) Bytes() []byte {
 // reference to a file-local static symbol becomes a RIP-relative load whose
 // displacement is resolved against that layout; a reference to a symbol no
 // GLOBL defines is recorded as an external relocation (Externals) with its
-// displacement left zero — the object-file emitters resolve it at link
+// displacement left zero, the object-file emitters resolve it at link
 // time, while the raw image (Bytes) cannot represent it.
 func AssembleFile(f *ast.File) (*Image, error) {
 	dataSyms, err := collectData(f)
@@ -146,6 +151,7 @@ func AssembleFile(f *ast.File) (*Image, error) {
 	link := &linkInfo{symbols: known, allowExternal: true}
 
 	img := &Image{Symbols: map[string]int{}}
+	textOff := map[string]int{}
 	type asmFunc struct {
 		name    string
 		patches []sbPatch
@@ -183,6 +189,7 @@ func AssembleFile(f *ast.File) (*Image, error) {
 		for _, s := range steps {
 			fl.Spadj = append(fl.Spadj, SpadjStep{PC: s.pc, Value: s.value})
 		}
+		textOff[t.Name.Name] = len(img.Code)
 		img.Funcs = append(img.Funcs, fl)
 		img.Code = append(img.Code, code...)
 		funcs = append(funcs, asmFunc{name: t.Name.Name, patches: patches})
@@ -215,13 +222,27 @@ func AssembleFile(f *ast.File) (*Image, error) {
 		base := img.Funcs[i].Offset
 		code := img.Code[base : base+img.Funcs[i].Size]
 		for _, p := range fn.patches {
-			reloc := Reloc{Off: p.off, After: p.after, Name: p.name, Addend: p.addend}
+			reloc := Reloc{Off: p.off, After: p.after, Name: p.name, Addend: p.addend, Kind: p.kind}
+			if p.kind == RelTLSLE {
+				// The TLS slot has no symbol: the linker fills the offset
+				// from the runtime's TLS layout.
+				img.Funcs[i].Relocs = append(img.Funcs[i].Relocs, reloc)
+				continue
+			}
 			if imgOff, ok := img.Symbols[p.name]; ok {
 				rel := int64(imgOff) + p.addend - int64(base+p.after)
 				if rel < -1<<31 || rel >= 1<<31 {
 					return nil, fmt.Errorf("%s: displacement to %q out of rel32 range", fn.name, p.name)
 				}
 				copy(code[p.off:p.off+4], le32(rel))
+			} else if imgOff, ok := textOff[p.name]; ok {
+				// A CALL to a TEXT function of the same file: resolve the
+				// displacement against the function's layout position.
+				rel := int64(imgOff) + p.addend - int64(base+p.after)
+				if rel < -1<<31 || rel >= 1<<31 {
+					return nil, fmt.Errorf("%s: displacement to %q out of rel32 range", fn.name, p.name)
+				}
+				copy(code[p.off:p.off+4], le32(rel))
 			} else {
 				reloc.External = true
 				externals[p.name] = true
@@ -419,50 +440,63 @@ type dataSym struct {
 }
 
 // collectData gathers the file's static symbols (GLOBL) and their initial
-// contents (DATA) into byte buffers, in declaration order.
+// contents (DATA) into byte buffers.  Two passes: the Plan 9 convention puts
+// every DATA line before its symbol's GLOBL, so the symbols are registered
+// before the initialisers are applied.
 func collectData(f *ast.File) ([]dataSym, error) {
 	index := map[string]int{}
 	var syms []dataSym
 	for _, d := range f.Decls {
-		switch dd := d.(type) {
+		gd, ok := d.(*ast.Globl)
-		case *ast.Globl:
+		if !ok {
-			if dd.Name == nil || dd.Name.Pseudo != "SB" {
 			continue
 		}
-			name := dd.Name.Name
+		if gd.Name == nil || gd.Name.Pseudo != "SB" {
+			continue
+		}
+		name := gd.Name.Name
 		if _, dup := index[name]; dup {
 			return nil, fmt.Errorf("duplicate GLOBL %q", name)
 		}
 		size := 0
-			if dd.Size != nil && dd.Size.Imm.HasVal {
+		if gd.Size != nil && gd.Size.Imm.HasVal {
-				size = int(dd.Size.Imm.Val)
+			size = int(gd.Size.Imm.Val)
 		}
 		index[name] = len(syms)
 		ds := dataSym{
 			name:   name,
-				pkg:    dd.Name.Pkg,
+			pkg:    gd.Name.Pkg,
 			buf:    make([]byte, size),
 			size:   size,
-				static: dd.Name.Static,
+			static: gd.Name.Static,
 		}
-			for _, f := range dd.Flags {
+		for _, f := range gd.Flags {
 			switch f {
 			case "RODATA":
 				ds.rodata = true
 			case "DUPOK":
 				ds.dupok = true
-				case "1":
+			default:
-					ds.dupok = true
+				// Legacy numeric flag constants (runtime/textflag.h):
-				case "8":
+				// DUPOK is 2, RODATA is 8; combinations arrive as one
-					ds.rodata = true
+				// number (e.g. 10 = RODATA|DUPOK).
-				case "9":
+				if n, err := strconv.Atoi(f); err == nil {
+					if n&2 != 0 {
 						ds.dupok = true
+					}
+					if n&8 != 0 {
 						ds.rodata = true
 					}
 				}
+			}
+		}
 		syms = append(syms, ds)
-
+	}
-		case *ast.Data:
+	for _, d := range f.Decls {
+		dd, ok := d.(*ast.Data)
+		if !ok {
+			continue
+		}
 		if dd.Name == nil || dd.Name.Pseudo != "SB" {
 			continue
 		}
@@ -492,7 +526,6 @@ func collectData(f *ast.File) ([]dataSym, error) {
 			buf[off+int64(j)] = byte(v >> (8 * j))
 		}
 	}
-	}
 	return syms, nil
 }
 

asm/link_test.go

@@ -10,8 +10,8 @@ import (
 	"sourcedock.dev/petrbalvin/gasm-devkit/parser"
 )
 
-// TestAssembleFileStaticData checks the whole-image layout — code, padding
+// TestAssembleFileStaticData checks the whole-image layout; code, padding
-// and the data section — and that the RIP-relative displacements of static
+// and the data section; and that the RIP-relative displacements of static
 // symbol loads resolve to the right bytes.
 func TestAssembleFileStaticData(t *testing.T) {
 	f, errs := parser.Parse("d_amd64.s", `
@@ -128,3 +128,41 @@ DATA x<>+0(SB)/4, $1
 		t.Errorf("single-function SB: error %v, want a file-level-assembly error", err)
 	}
 }
+
+// TestCollectDataNumericFlags pins the numeric GLOBL flag constants from
+// runtime/textflag.h: DUPOK is 2, RODATA is 8, and combinations arrive as
+// one number (9 = NOPROF|RODATA, 10 = RODATA|DUPOK).
+func TestCollectDataNumericFlags(t *testing.T) {
+	tests := []struct {
+		flags  string
+		rodata bool
+		dupok  bool
+	}{
+		{"2", false, true},
+		{"8", true, false},
+		{"9", true, false}, // NOPROF|RODATA, not DUPOK
+		{"10", true, true}, // RODATA|DUPOK
+		{"RODATA", true, false},
+		{"DUPOK", false, true},
+		{"RODATA|DUPOK", true, true},
+	}
+	for _, tt := range tests {
+		src := "TEXT \u00b7f(SB), NOSPLIT, $0\n\tRET\nGLOBL sym(SB), " + tt.flags + ", $8\n"
+		f, errs := parser.Parse("f_amd64.s", src)
+		if len(errs) > 0 {
+			t.Fatalf("parse %q: %v", tt.flags, errs)
+		}
+		img, err := AssembleFile(f)
+		if err != nil {
+			t.Fatalf("assemble %q: %v", tt.flags, err)
+		}
+		if len(img.DataSyms) != 1 {
+			t.Fatalf("%q: data syms = %d, want 1", tt.flags, len(img.DataSyms))
+		}
+		d := img.DataSyms[0]
+		if d.Rodata != tt.rodata || d.Dupok != tt.dupok {
+			t.Errorf("flags %q: rodata=%v dupok=%v, want rodata=%v dupok=%v",
+				tt.flags, d.Rodata, d.Dupok, tt.rodata, tt.dupok)
+		}
+	}
+}

asm/loong64_assemble.go

@@ -6,6 +6,7 @@ package asm
 import (
 	"fmt"
 	"math/bits"
+	"strconv"
 	"strings"
 
 	"sourcedock.dev/petrbalvin/gasm-devkit/ast"
@@ -13,17 +14,19 @@ import (
 
 // assembleLOONG64 assembles a LoongArch (loong64) TEXT function body into
 // machine code.  Every instruction is 4 bytes; the MOV pseudo-instruction and
-// the immediate-arithmetic forms expand to 2–5 instructions when the
+// the immediate-arithmetic forms expand to 2-5 instructions when the
 // immediate does not fit, so the layout is computed in two passes (sizes,
 // then encoding with resolved branch targets).
 //
 // The emitted bytes match the Go toolchain's loong64 assembler, which is the
-// ground-truth oracle: prologue/epilogue, FP/SP frame mapping, branch
+// ground-truth oracle: prologue/epilogue (including the large-frame R30
-// encodings and the MOV immediate expansions all follow cmd/internal/obj/
+// materialisations), FP/SP frame mapping, the stack-split guard classes, and
-// loong64's asmout cases.
+// branch encodings all follow cmd/internal/obj/loong64.  The morestack block
+// at the end of split functions carries the runtime.morestack_noctxt call.
 func assembleLOONG64(t *ast.Text) ([]byte, map[string]int, []Reloc, []LineEntry, []SpadjStep, error) {
 	fi := loong64ComputeFrame(t)
 	prologue := loong64Prologue(fi)
+	guardLen := loong64GuardLen(fi)
 	chain := loong64JumpChain(t)
 	resolve := func(name string) string {
 		if r, ok := chain[name]; ok {
@@ -35,16 +38,17 @@ func assembleLOONG64(t *ast.Text) ([]byte, map[string]int, []Reloc, []LineEntry,
 	var relocs []Reloc
 	var spadj []SpadjStep
 
-	// The prologue (3 instructions when a frame is present) raises the SP
+	// The prologue raises the SP delta by autosize; the boundary is reported
-	// delta by autosize; the boundary is reported at the third instruction's
+	// after the SP adjust instruction, exactly as the toolchain's pctospadj
-	// pc, exactly as the toolchain's pctospadj does.
+	// does.  The prologue (3 instructions when a frame is present) may
+	// materialise its store or adjust through R30, which widens it.
 	if fi.autosize != 0 {
-		spadj = append(spadj, SpadjStep{PC: 8, Value: fi.autosize})
+		spadj = append(spadj, SpadjStep{PC: guardLen + (loong64StoreWords(fi.autosize)+loong64AdjustWords(-int64(fi.autosize)))*4, Value: fi.autosize})
 	}
 
 	// Pass 1: label offsets from the instruction sizes.
 	offsets := map[string]int{}
-	pos := len(prologue)
+	pos := guardLen + len(prologue)
 	for _, stmt := range t.Body {
 		switch s := stmt.(type) {
 		case *ast.Label:
@@ -54,9 +58,25 @@ func assembleLOONG64(t *ast.Text) ([]byte, map[string]int, []Reloc, []LineEntry,
 		}
 	}
 
-	// Pass 2: encode.  Relocation offsets are recorded function-relative.
+	// Pass 2: encode.  The guard prefix precedes the prologue; its branches
-	out := append([]byte(nil), prologue...)
+	// target the morestack block at the end of the function, which the first
-	pc := len(prologue)
+	// pass has sized.
+	bodyLen := 0
+	{
+		p := guardLen + len(prologue)
+		for _, stmt := range t.Body {
+			if in, ok := stmt.(*ast.Instr); ok {
+				p += loong64InstrSize(in, fi)
+			}
+		}
+		bodyLen = p - (guardLen + len(prologue))
+	}
+	var out []byte
+	if fi.needSplit {
+		out = append(out, loong64GuardBytes(fi, guardLen+len(prologue)+bodyLen)...)
+	}
+	out = append(out, prologue...)
+	pc := guardLen + len(prologue)
 	preCount := len(relocs)
 	var lines []LineEntry
 	for _, stmt := range t.Body {
@@ -69,23 +89,29 @@ func assembleLOONG64(t *ast.Text) ([]byte, map[string]int, []Reloc, []LineEntry,
 			return nil, nil, nil, nil, nil, fmt.Errorf("%s: %w", in.Mnemonic.Text, err)
 		}
 		for j := preCount; j < len(relocs); j++ {
-			relocs[j].Off += pc - len(prologue)
+			// Make the relocation offsets function-relative: each instruction
+			// records its reloc offset relative to its own start, and pc is
+			// that instruction's offset from the function start (prologue
+			// included).  After shifts by the same amount.
+			relocs[j].Off += pc
+			relocs[j].After += pc
 		}
 		preCount = len(relocs)
 		lines = append(lines, LineEntry{Offset: pc, Line: in.Pos().Line})
 		// The RET's epilogue closes the frame: the SP delta returns to zero
-		// after the addi.d (one instruction for a leaf, two for a non-leaf
+		// after the frame-deallocating ADDV.
-		// with the LR restore).
 		if strings.ToUpper(in.Mnemonic.Text) == "RET" && fi.autosize != 0 {
-			epi := 4
+			spadj = append(spadj, SpadjStep{PC: pc + loong64EpilogueWords(fi)*4, Value: 0})
-			if !fi.leaf {
-				epi = 8
-			}
-			spadj = append(spadj, SpadjStep{PC: pc + epi, Value: 0})
 		}
 		out = append(out, code...)
 		pc += len(code)
 	}
+	if fi.needSplit {
+		block, blReloc := loong64MoreStackBlock(pc)
+		out = append(out, block...)
+		relocs = append(relocs, blReloc)
+		pc += len(block)
+	}
 	return out, offsets, relocs, lines, spadj, nil
 }
 
@@ -224,15 +250,18 @@ func encodeLOONG64Instr(instr *ast.Instr, pc int, offsets map[string]int, fi loo
 		}
 		return l64wordLE(uint32(immFromOperand(ops[0]))), nil
 	case "JMP", "B":
-		return encodeLOONG64Branch(instr, mnem, pc, offsets, false, resolve)
+		return encodeLOONG64Branch(instr, mnem, pc, offsets, false, resolve, relocs)
 	case "JAL", "CALL", "BL":
-		return encodeLOONG64Branch(instr, mnem, pc, offsets, true, resolve)
+		return encodeLOONG64Branch(instr, mnem, pc, offsets, true, resolve, relocs)
 	case "MOV", "MOVB", "MOVH", "MOVW", "MOVV", "MOVBU", "MOVHU", "MOVWU", "MOVF", "MOVD":
 		return encodeLOONG64Mov(instr, mnem, fi, relocs)
 	}
 
 	// 16-bit branches (BEQ/BNE/BLT/BGE/BLTU/BGEU) and JIRL.
 	if op, ok := l64branchTable[mnem]; ok {
+		if mnem == "JIRL" {
+			return encodeLOONG64Jirl(op, ops)
+		}
 		return encodeLOONG64Branch16(mnem, op, ops, pc, offsets, resolve)
 	}
 	// Single-register branches with 21-bit offsets (BLTZ/BGEZ/BLEZ/BGTZ,
@@ -417,7 +446,7 @@ func encodeLOONG64Instr(instr *ast.Instr, pc int, offsets map[string]int, fi loo
 
 	case l64Firrr:
 		// ALSL: INSTR $sa, rj, rk, rd (the toolchain's optab places rj in
-		// the second register position); the source amount is 1–4, encoded
+		// the second register position); the source amount is 1-4, encoded
 		// as sa-1.
 		if len(ops) != 4 {
 			return nil, fmt.Errorf("%s expects 4 operands, got %d", mnem, len(ops))
@@ -485,7 +514,7 @@ func encodeLOONG64Instr(instr *ast.Instr, pc int, offsets map[string]int, fi loo
 //
 //	JMP/B label      → b label            JMP/B (rj) → jirl r0, rj, 0
 //	JAL/CALL/BL label → bl label          JAL/CALL/BL (rj) → jirl r1, rj, 0
-func encodeLOONG64Branch(instr *ast.Instr, mnem string, pc int, offsets map[string]int, link bool, resolve func(string) string) ([]byte, error) {
+func encodeLOONG64Branch(instr *ast.Instr, mnem string, pc int, offsets map[string]int, link bool, resolve func(string) string, relocs *[]Reloc) ([]byte, error) {
 	if len(instr.Operands) != 1 {
 		return nil, fmt.Errorf("%s expects 1 operand, got %d", mnem, len(instr.Operands))
 	}
@@ -502,6 +531,19 @@ func encodeLOONG64Branch(instr *ast.Instr, mnem string, pc int, offsets map[stri
 		}
 		return l64wordLE(l64irr16(l64branchTable["JIRL"], 0, rj, rd)), nil
 	}
+	// Direct symbol: sym+off(SB) → b/bl with an R_CALLLOONG64 relocation
+	// (the linker fills the offset), as the toolchain does for CALL/BL/JAL
+	// and for tail-calling JMP.
+	if op.Addr.Sym != nil && op.Addr.Sym.Pseudo == "SB" {
+		opc := l64jumpTable["B"]
+		if link {
+			opc = l64jumpTable["BL"]
+		}
+		if relocs != nil {
+			*relocs = append(*relocs, Reloc{Off: 0, After: 4, Name: op.Addr.Sym.Name, Kind: RelLoong64Branch, Addend: op.Addr.Sym.Offset})
+		}
+		return l64wordLE(l64bbl(opc, 0)), nil
+	}
 	// Direct: label → b/bl.
 	target := resolve(l64Label(op))
 	targetOff, ok := offsets[target]
@@ -516,6 +558,46 @@ func encodeLOONG64Branch(instr *ast.Instr, mnem string, pc int, offsets map[stri
 	return l64wordLE(l64bbl(opc, v)), nil
 }
 
+// encodeLOONG64Jirl encodes the raw JIRL spelling, JIRL rd, rj, offset, the
+// form the verify trampolines use.  The (rj) indirect form without an offset
+// is handled by encodeLOONG64Branch.
+func encodeLOONG64Jirl(op uint32, ops []*ast.Operand) ([]byte, error) {
+	if len(ops) != 3 {
+		return nil, fmt.Errorf("JIRL expects 3 operands, got %d", len(ops))
+	}
+	rd := l64Reg(ops[0])
+	rj := l64Reg(ops[1])
+	if rd < 0 || rj < 0 {
+		return nil, fmt.Errorf("invalid register operand")
+	}
+	off, ok := l64offsetOperand(ops[2])
+	if !ok {
+		return nil, fmt.Errorf("JIRL expects an immediate offset, got %q", ops[2].Raw)
+	}
+	if (int64(off)<<16)>>16 != int64(off) {
+		return nil, fmt.Errorf("JIRL offset %d out of the 16-bit range", off)
+	}
+	return l64wordLE(l64irr16(op, int(off), rj, rd)), nil
+}
+
+// l64offsetOperand reads a bare numeric branch offset: an immediate ($n) or a
+// plain number, which parses as an empty address carrying the digits in Raw.
+func l64offsetOperand(op *ast.Operand) (int32, bool) {
+	if op.Imm.HasVal {
+		v := op.Imm.Val
+		if op.Imm.Neg {
+			v = -v
+		}
+		return int32(v), true
+	}
+	if op.Kind == ast.OpAddr && op.Addr.Sym == nil && op.Addr.Base == "" && op.Addr.Index == "" {
+		if v, err := strconv.ParseInt(op.Raw, 0, 64); err == nil {
+			return int32(v), true
+		}
+	}
+	return 0, false
+}
+
 // encodeLOONG64Branch16 encodes a 16-bit branch (BEQ/BNE/BLT/BGE/BLTU/BGEU):
 // INSTR rj, rd, label, or INSTR rj, label with rd = R0, which the toolchain
 // turns into the 21-bit BEQZ/BNEZ form when the register is the only operand.
@@ -578,8 +660,8 @@ func encodeLOONG64Branch16(mnem string, op uint32, ops []*ast.Operand, pc int, o
 
 // encodeLOONG64Branch21 encodes a single-register branch: BLTZ/BGEZ and
 // BFPT/BFPF use the 21-bit offset form (register in the rj field), while
-// BGTZ/BLEZ — which the toolchain encodes with the register in the rd field
+// BGTZ/BLEZ, which the toolchain encodes with the register in the rd field
-// and a 16-bit offset — are handled separately.
+// and a 16-bit offset, are handled separately.
 func encodeLOONG64Branch21(mnem string, op uint32, ops []*ast.Operand, pc int, offsets map[string]int, resolve func(string) string) ([]byte, error) {
 	if len(ops) != 2 {
 		return nil, fmt.Errorf("%s expects 2 operands, got %d", mnem, len(ops))
@@ -692,7 +774,7 @@ func encodeLOONG64ImmArith(mnem string, de l64DualEnc, ops []*ast.Operand) ([]by
 }
 
 // isLoong64ShiftD reports whether a shift-immediate opcode constant is one of
-// the 6-bit (.d) variants — the toolchain distinguishes them by the bit
+// the 6-bit (.d) variants, the toolchain distinguishes them by the bit
 // position of the opcode field (bits [25:16]).
 func isLoong64ShiftD(op uint32) bool {
 	return op&0x03ff0000 != 0 && op>>25 == 0
@@ -740,7 +822,7 @@ func l64MemOperands(ops []*ast.Operand, fi loong64FrameInfo) (rd, rj int, off in
 
 // ---- the MOV pseudo-instruction ----
 
-// encodeLOONG64Mov encodes the MOV family — the load/store/immediate
+// encodeLOONG64Mov encodes the MOV family, the load/store/immediate
 // workhorse of Go's loong64 assembly.  MOV is an alias of MOVV (the width
 // mnemonics MOVB/MOVH/MOVW/MOVV/MOVBU/MOVHU/MOVWU/MOVF/MOVD select the
 // access width).  The forms, mirroring the toolchain:

asm/loong64_encode.go

@@ -9,7 +9,7 @@ package asm
 // an opcode constant, and the format selects the bit layout.  The opcode
 // constants and formats are transcribed from the Go toolchain's own loong64
 // backend (cmd/internal/obj/loong64), so the emitted bytes match `go tool asm`
-// exactly — the ground-truth oracle for the verify suite.
+// exactly, the ground-truth oracle for the verify suite.
 //
 // All LoongArch instructions are 32 bits, little-endian.  The formats used
 // here (per the LoongArch Volume I specification):
@@ -33,8 +33,8 @@ package asm
 import "maps"
 
 // loong64RegNum returns the 5-bit register number for a LoongArch register
-// name: R0–R31 (integer), F0–F31 (floating point), FCC0–FCC7 (condition
+// name: R0-R31 (integer), F0-F31 (floating point), FCC0-FCC7 (condition
-// flags), FCSR0–FCSR31 (control/status) and the ABI aliases the runtime's
+// flags), FCSR0-FCSR31 (control/status) and the ABI aliases the runtime's
 // assembly uses.  Returns -1 for an unrecognised name.
 func loong64RegNum(name string) int {
 	switch name {
@@ -103,7 +103,7 @@ func loong64RegNum(name string) int {
 	case "R31", "S8":
 		return 31
 	}
-	// F0–F31, FCC0–FCC7, FCSR0–FCSR31.
+	// F0-F31, FCC0-FCC7, FCSR0-FCSR31.
 	if len(name) >= 4 && name[:4] == "FCSR" {
 		return loong64RegSpecial(name[4:], 31)
 	}
@@ -199,7 +199,7 @@ func l64rrrr(op uint32, r1, r2, r3, r4 int) uint32 {
 }
 
 // l64irir encodes a BSTRINS/BSTRPICK instruction: op | msb<<16 | rj<<5 | lsb<<10 | rd.
-// The msb/lsb fields are 6 bits wide (0–63) and are validated by the caller.
+// The msb/lsb fields are 6 bits wide (0-63) and are validated by the caller.
 func l64irir(op uint32, msb, rj, lsb, rd int) uint32 {
 	return op | uint32(msb)<<16 | uint32(rj&0x1f)<<5 | uint32(lsb)<<10 | uint32(rd&0x1f)
 }
@@ -280,7 +280,7 @@ var l64DualTable = map[string]l64DualEnc{}
 var l64InstrTable = map[string]l64Enc{}
 
 func init() {
-	// 3R — integer.
+	// 3R, integer.
 	rrr := map[string]uint32{
 		"ADD": 0x20 << 15, "ADDW": 0x20 << 15, "ADDV": 0x21 << 15, "ADDVU": 0x21 << 15,
 		"SUB": 0x22 << 15, "SUBW": 0x22 << 15, "SUBV": 0x23 << 15, "SUBVU": 0x23 << 15,
@@ -300,7 +300,7 @@ func init() {
 		"CRCWBW": 0x48 << 15, "CRCWHW": 0x49 << 15, "CRCWWW": 0x4a << 15, "CRCWVW": 0x4b << 15,
 		"CRCCWBW": 0x4c << 15, "CRCCWHW": 0x4d << 15, "CRCCWWW": 0x4e << 15, "CRCCWVW": 0x4f << 15,
 	}
-	// 3R — floating point.
+	// 3R, floating point.
 	rrr["MULF"] = 0x209 << 15
 	rrr["MULD"] = 0x20a << 15
 	rrr["DIVF"] = 0x20d << 15
@@ -390,12 +390,12 @@ func init() {
 		"ROTRV": {rrr: 0x37 << 15, imm: 0x004d << 16, shift: true},
 	})
 
-	// 2RI12 — pure immediate arithmetic (LU52ID has no register form).
+	// 2RI12, pure immediate arithmetic (LU52ID has no register form).
 	l64InstrTable["LU52ID"] = l64Enc{format: l64Firr, op: 0x00c << 22}
 	// ADDV16 (addu16i.d): 2RI16 with the immediate shifted right by 16.
 	l64InstrTable["ADDV16"] = l64Enc{format: l64Firr16, op: 0x4 << 26}
 
-	// 2RI14 — LL/SC are aliased by the Go assembler to the pointer loads and
+	// 2RI14, LL/SC are aliased by the Go assembler to the pointer loads and
 	// stores (ldptr/stptr), with the offset scaled by 4.
 	l64InstrTable["MOVWP"] = l64Enc{format: l64Firr14, op: 0x25 << 24} // stptr.w
 	l64InstrTable["MOVVP"] = l64Enc{format: l64Firr14, op: 0x27 << 24} // stptr.d
@@ -414,7 +414,7 @@ func init() {
 	// LUI is the Plan 9 spelling of lu12i.w.
 	l64InstrTable["LUI"] = l64Enc{format: l64Fir20, op: 0x0a << 25}
 
-	// 4R — fused multiply-add.
+	// 4R, fused multiply-add.
 	rrrr := map[string]uint32{
 		"FMADDF": 0x81 << 20, "FMADDD": 0x82 << 20,
 		"FMSUBF": 0x85 << 20, "FMSUBD": 0x86 << 20,
@@ -425,7 +425,7 @@ func init() {
 		l64InstrTable[m] = l64Enc{format: l64Frrrr, op: op}
 	}
 
-	// IRIR — bit-field insert/extract.
+	// IRIR, bit-field insert/extract.
 	irir := map[string]uint32{
 		"BSTRINSW":  0x3<<21 | 0x0<<15,
 		"BSTRINSV":  0x2 << 22,
@@ -436,7 +436,7 @@ func init() {
 		l64InstrTable[m] = l64Enc{format: l64Firir, op: op}
 	}
 
-	// 3RI2 — ALSL.
+	// 3RI2, ALSL.
 	irrr := map[string]uint32{
 		"ALSLW": 0x2 << 17, "ALSLWU": 0x3 << 17, "ALSLV": 0x16 << 17,
 	}
@@ -452,7 +452,7 @@ func init() {
 	// PRELD.
 	l64InstrTable["PRELD"] = l64Enc{format: l64Fpreld, op: 0x0ab << 22}
 
-	// Atomics — 3R with the AM field order (rk=value, rj=address, rd=result).
+	// Atomics, 3R with the AM field order (rk=value, rj=address, rd=result).
 	am := map[string]uint32{
 		"AMSWAPB": 0x070B8 << 15, "AMSWAPH": 0x070B9 << 15,
 		"AMSWAPW": 0x070C0 << 15, "AMSWAPV": 0x070C1 << 15,
@@ -477,7 +477,7 @@ func init() {
 }
 
 // l64FpMovTable maps (mnemonic, from-class, to-class) to the 2R opcode of the
-// register move between the integer and floating-point register banks — the
+// register move between the integer and floating-point register banks, the
 // MOVW/MOVV specials the Go assembler accepts.
 var l64FpMovTable = map[string]uint32{
 	"MOVV.R.F":    0x452a << 10, // movgr2fr.d

asm/loong64_encode_test.go

@@ -291,3 +291,40 @@ done:
 		t.Errorf("code = % x\nwant % x", code, want)
 	}
 }
+
+// TestLOONG64IndirectBranch pins the indirect branch encodings: JMP (Rj) and
+// JAL (Rj) lower to jirl, and the raw JIRL spelling encodes the written
+// offset (the Go loong64 assembler deletes raw JIRL instructions entirely,
+// so this form is a gasm-only superset with faithful semantics).
+func TestLOONG64IndirectBranch(t *testing.T) {
+	fn := firstTextLOONG64(t, `#include "textflag.h"
+TEXT ·f(SB), NOSPLIT, $0-0
+	JMP (R4)
+	JIRL R0, R4, 8
+	RET
+`)
+	code := assembleLOONG64Helper(t, fn)
+	wantWords(t, code,
+		0x4C000080, // jirl r0, r4, 0
+		0x4C002080, // jirl r0, r4, 8
+		0x4C000020, // jirl r0, r1, 0 (RET)
+	)
+
+	// JAL (R5) links, so the toolchain gives the function its autosize-8
+	// prologue and epilogue around the call and the closing RET.
+	fn = firstTextLOONG64(t, `#include "textflag.h"
+TEXT ·f(SB), NOSPLIT, $0-0
+	JAL (R5)
+	RET
+`)
+	code = assembleLOONG64Helper(t, fn)
+	wantWords(t, code,
+		0x29FFE061, // addi.d r1, r2, -8 (prologue)
+		0x02FFE063, // addi.d r3, r3, -8
+		0x29C00061, // st.d r1, r2, 0 (prologue saves RA)
+		0x4C0000A1, // jirl r1, r5, 0
+		0x28C00061, // ld.d r1, r2, 0 (epilogue restores RA)
+		0x02C02063, // addi.d r3, r3, 8
+		0x4C000020, // jirl r0, r1, 0 (RET)
+	)
+}

asm/loong64_frame.go

@@ -20,14 +20,20 @@ import (
 // (the toolchain aligns frames with `if autosize&4 != 0 { autosize += 4 }`).
 // A leaf function (no calls) with a zero frame gets no prologue at all.
 //
-// Prologue (autosize > 0), byte-identical to the toolchain:
+// Prologue (autosize > 0, small), byte-identical to the toolchain:
 //
 //	MOVV R1, -autosize(R3)   // save LR below the new SP (traceback-safe)
 //	ADDV $-autosize, R3      // open the frame
 //	MOVV R1, 0(R3)           // save LR again at SP (signal-safety)
 //
+// Large frames (autosize past the 12-bit offset or immediate ranges) expand
+// the store and the adjust through REGTMP (R30) exactly as the toolchain's
+// assembler does: the store via the rounding LU12IW split, the adjust via
+// the floor LU12IW/ORI split.
+//
 // Epilogue: MOVV 0(R3), R1; ADDV $autosize, R3 (non-leaf only for the LR
-// restore); the RET's jirl r0, r1, 0 follows.
+// restore; the adjust materialised when the immediate does not fit); the
+// RET's jirl r0, r1, 0 follows.
 
 // loong64FrameInfo holds the frame layout derived from a TEXT directive.
 type loong64FrameInfo struct {
@@ -36,6 +42,11 @@ type loong64FrameInfo struct {
 	args     int  // the declared -argsize
 	noSplit  bool // the NOSPLIT flag
 	leaf     bool // no call instructions in the body
+
+	// Stack-split guard state: like amd64 and arm64, a leaf function with a
+	// small autosize is auto-marked NOSPLIT by the toolchain.
+	needSplit  bool
+	splitClass int // 0: <=StackSmall, 1: <=StackBig, 2: >StackBig
 }
 
 // loong64ComputeFrame derives the frame layout for a TEXT function.
@@ -59,9 +70,157 @@ func loong64ComputeFrame(t *ast.Text) loong64FrameInfo {
 		// A zero-frame non-leaf function still opens an 8-byte frame for LR.
 		fi.autosize = 8
 	}
+	switch {
+	case fi.noSplit:
+	case fi.autosize < stackSmall && fi.leaf:
+		// Auto-NOSPLIT, as the toolchain's leaf mark concludes.
+	default:
+		fi.needSplit = true
+		switch {
+		case fi.autosize <= stackSmall:
+			fi.splitClass = 0
+		case fi.autosize <= stackBig:
+			fi.splitClass = 1
+		default:
+			fi.splitClass = 2
+		}
+	}
 	return fi
 }
 
+// loong64GuardLen returns the byte length of the stack-split guard prefix
+// (zero when the function needs no guard).  The big class materialises two
+// constants through R30; each materialisation shrinks by one word when the
+// constant's low 12 bits are zero.
+func loong64GuardLen(fi loong64FrameInfo) int {
+	if !fi.needSplit {
+		return 0
+	}
+	off := int64(fi.autosize - stackSmall)
+	switch fi.splitClass {
+	case 0:
+		return 12
+	case 1:
+		if off <= 2048 {
+			return 16 // ADDV $-off fits the signed 12-bit immediate
+		}
+		return 24 // MOVV + LU12IW + ORI + ADDV + SGTU + BEQ
+	default:
+		// MOVV + [mat] + SGTU + BNE + [mat] + ADDV + SGTU + BEQ
+		return (6 + loong64MatLen(off) + loong64MatLen(-off)) * 4
+	}
+}
+
+// loong64MatLen reports the word count of materialising v in R30: a value
+// with a zero high part needs only the ORI (the toolchain's MOVW $v, R30),
+// one with a zero low part only the LU12IW.
+func loong64MatLen(v int64) int {
+	if v>>12 == 0 || v&0xFFF == 0 {
+		return 1
+	}
+	return 2
+}
+
+// loong64MatWords appends the words that materialise v in R30, splitting it
+// as v>>12 plus the zero-extended low 12 bits.
+func loong64MatWords(ws []uint32, v int64) []uint32 {
+	hi := v >> 12
+	lo := v & 0xFFF
+	if hi == 0 {
+		return append(ws, l64irr(l64OriOp, int(v), 0, 30))
+	}
+	ws = append(ws, l64ir(l64Lu12iwOp, int(hi), 30))
+	if lo != 0 {
+		ws = append(ws, l64irr(l64OriOp, int(lo), 30, 30))
+	}
+	return ws
+}
+
+// The LU12IW and ORI opcode bases (2RI20 and 2RI12 formats); the ORI reads
+// and writes rd itself.
+const (
+	l64Lu12iwOp = 0x0a << 25
+	l64OriOp    = 0x0e << 22
+)
+
+// loong64Imm12 reports whether v fits a signed 12-bit immediate.
+func loong64Imm12(v int64) bool { return v >= -2048 && v <= 2047 }
+
+// loong64GuardBytes emits the stack-split guard prefix.  blockStart is the
+// function-relative address of the morestack call at the end of the function;
+// branch displacements are in instructions and are computed from each
+// branch's own position.
+func loong64GuardBytes(fi loong64FrameInfo, blockStart int) []byte {
+	// MOVV 16(g), R20 (g.stackguard0), g = R22.
+	ws := []uint32{l64irr(l64loadStoreTable["MOVV"].ld, 16, 22, 20)}
+	off := int64(fi.autosize - stackSmall)
+	// beq appends BEQ R20, blockStart from the branch's own position.
+	beq := func() {
+		ws = append(ws, loong64Beqz(20, int32((blockStart-len(ws)*4)>>2)))
+	}
+	switch fi.splitClass {
+	case 0:
+		// SGTU SP, R20, R20; BEQ R20, more
+		ws = append(ws, l64rrr(l64DualTable["SGTU"].rrr, 3, 20, 20))
+		beq()
+	case 1:
+		ws = append(ws, loong64MediumWords(off)...)
+		ws = append(ws, l64rrr(l64DualTable["SGTU"].rrr, 24, 20, 20))
+		beq()
+	default:
+		// SGTU $off, SP, R24 catches the SP underflow a huge frame would
+		// cause; BNE jumps to morestack in that case.
+		ws = append(ws, loong64MatWords(nil, off)...)
+		ws = append(ws, l64rrr(l64DualTable["SGTU"].rrr, 30, 3, 24))
+		ws = append(ws, loong64Bnez(24, int32((blockStart-len(ws)*4)>>2)))
+		ws = append(ws, loong64MatWords(nil, -off)...)
+		ws = append(ws, l64rrr(l64DualTable["ADDV"].rrr, 30, 3, 24))
+		ws = append(ws, l64rrr(l64DualTable["SGTU"].rrr, 24, 20, 20))
+		beq()
+	}
+	return l64WordsLE(ws...)
+}
+
+// loong64MediumWords emits the medium-class stack check for offset off: the
+// ADDV immediate when it fits, otherwise the same sequence with the constant
+// materialised in R30.
+func loong64MediumWords(off int64) []uint32 {
+	if off <= 2048 {
+		return []uint32{l64irr(l64DualTable["ADDV"].imm, int(-off), 3, 24)}
+	}
+	ws := loong64MatWords(nil, -off)
+	return append(ws, l64rrr(l64DualTable["ADDV"].rrr, 30, 3, 24))
+}
+
+// loong64Beqz/loong64Bnez build the 21-bit conditional branches against R0
+// that the toolchain emits for its guard compares.
+func loong64Beqz(rj int, dispInstr int32) uint32 {
+	return l64ir21(l64branch21Table["BEQZ"], int(dispInstr), rj)
+}
+
+func loong64Bnez(rj int, dispInstr int32) uint32 {
+	return l64ir21(l64branch21Table["BNEZ"], int(dispInstr), rj)
+}
+
+// loong64MoreStackBlock emits the trailing block: MOVV R1, R31 (save LR, the
+// toolchain's OR R1, R0, R31 expansion), BL runtime.morestack_noctxt, B back
+// to the function entry.
+func loong64MoreStackBlock(blockStart int) ([]byte, Reloc) {
+	ws := []uint32{
+		l64rrr(l64DualTable["OR"].rrr, 0, 1, 31), // MOVV R1, R31 (OR R1, R0, R31)
+		l64bbl(l64jumpTable["BL"], 0),            // BL, patched by the linker
+	}
+	disp := (-(blockStart + 8)) >> 2
+	ws = append(ws, l64bbl(l64jumpTable["B"], int(disp)))
+	reloc := Reloc{
+		Off:   blockStart + 4,
+		After: blockStart + 8,
+		Name:  "runtime\u00b7morestack_noctxt",
+		Kind:  RelLoong64Branch,
+	}
+	return l64WordsLE(ws...), reloc
+}
+
 // loong64IsLeaf reports whether a function contains no call instructions
 // (JAL/BL/CALL), matching the toolchain's LEAF mark, which drives the frame
 // and the epilogue shape.
@@ -79,17 +238,37 @@ func loong64IsLeaf(t *ast.Text) bool {
 	return true
 }
 
-// loong64Prologue returns the prologue bytes for a loong64 function.
+// loong64Prologue returns the prologue bytes for a loong64 function.  When
+// the LR store offset leaves the toolchain's 12-bit store range ([-2046,
+// 2045], BIG_12 = 2046) or the SP adjust immediate its 12-bit immediate
+// range, each switches to the R30 materialisation the assembler expands it
+// to: the store uses the rounding %hi/%lo split (LU12IW of (v+2048)>>12,
+// REGTMP += SP, store at the raw offset), the adjust the floor split
+// (LU12IW, ORI when the low part is non-zero, REGTMP += SP).
 func loong64Prologue(fi loong64FrameInfo) []byte {
 	if fi.autosize == 0 {
 		return nil
 	}
 	addiD := l64DualTable["ADDV"].imm
-	return l64WordsLE(
+	var ws []uint32
-		l64irr(l64loadStoreTable["MOVV"].st, -fi.autosize, 3, 1), // MOVV R1, -autosize(R3)
+	storeBase := 3
-		l64irr(addiD, -fi.autosize, 3, 3),                        // ADDV $-autosize, R3
+	if fi.autosize > 2046 {
-		l64irr(l64loadStoreTable["MOVV"].st, 0, 3, 1),            // MOVV R1, 0(R3)
+		// The store goes through REGTMP: LU12IW of the rounding split,
-	)
+		// REGTMP += SP, then the store at REGTMP with the truncated offset.
+		v := -int64(fi.autosize)
+		ws = append(ws, l64ir(l64Lu12iwOp, int((v+2048)>>12), 30))
+		ws = append(ws, l64rrr(l64DualTable["ADDV"].rrr, 3, 30, 30))
+		storeBase = 30
+	}
+	ws = append(ws, l64irr(l64loadStoreTable["MOVV"].st, -fi.autosize, storeBase, 1)) // MOVV R1, -autosize(base)
+	if loong64Imm12(-int64(fi.autosize)) {
+		ws = append(ws, l64irr(addiD, -fi.autosize, 3, 3)) // ADDV $-autosize, R3
+	} else {
+		ws = append(ws, loong64MatWords(nil, -int64(fi.autosize))...)
+		ws = append(ws, l64rrr(l64DualTable["ADDV"].rrr, 30, 3, 3))
+	}
+	ws = append(ws, l64irr(l64loadStoreTable["MOVV"].st, 0, 3, 1)) // MOVV R1, 0(R3)
+	return l64WordsLE(ws...)
 }
 
 // loong64Return returns the bytes for a RET: the epilogue (restore LR and
@@ -98,17 +277,49 @@ func loong64Return(fi loong64FrameInfo) []byte {
 	var ws []uint32
 	if fi.autosize != 0 {
 		if !fi.leaf {
-			// MOVV 0(R3), R1 — restore the link register.
+			// MOVV 0(R3), R1, restore the link register.
 			ws = append(ws, l64irr(l64loadStoreTable["MOVV"].ld, 0, 3, 1))
 		}
-		// ADDV $autosize, R3 — close the frame.
+		// ADDV $autosize, R3, close the frame (materialised when the
+		// immediate does not fit).
+		if loong64Imm12(int64(fi.autosize)) {
 			ws = append(ws, l64irr(l64DualTable["ADDV"].imm, fi.autosize, 3, 3))
+		} else {
+			ws = append(ws, loong64MatWords(nil, int64(fi.autosize))...)
+			ws = append(ws, l64rrr(l64DualTable["ADDV"].rrr, 30, 3, 3))
 		}
-	// jirl r0, r1, 0 — return.
+	}
+	// jirl r0, r1, 0, return.
 	ws = append(ws, l64irr16(l64branchTable["JIRL"], 0, 1, 0))
 	return l64WordsLE(ws...)
 }
 
+// loong64StoreWords reports the prologue word count of the LR store, and
+// loong64AdjustWords the word count of an SP adjust of v: the immediate
+// forms when they fit, otherwise the R30 materialisation sequences.
+func loong64StoreWords(autosize int) int {
+	if autosize > 2046 {
+		return 3
+	}
+	return 1
+}
+
+func loong64AdjustWords(v int64) int {
+	if loong64Imm12(v) {
+		return 1
+	}
+	return loong64MatLen(v) + 1
+}
+
+// loong64EpilogueWords reports the epilogue word count the RET expands to.
+func loong64EpilogueWords(fi loong64FrameInfo) int {
+	n := loong64AdjustWords(int64(fi.autosize))
+	if !fi.leaf {
+		n++
+	}
+	return n
+}
+
 // loong64ResolvePseudo translates a pseudo-register memory reference into a
 // hardware base register and offset.  x+N(FP) → (N + autosize + 8)(SP);
 // x-N(SP) → (autosize - N)(SP).  Returns base = -1 for an unresolvable

asm/loong64_more_test.go

@@ -280,7 +280,7 @@ done:
 // TestLOONG64_pcsp checks the stack-adjustment table of a framed function:
 // the prologue raises the SP delta by autosize (in effect from the third
 // instruction) and the RET's epilogue restores it to zero, with the pc deltas
-// in MinLC (4) units — byte-identical to `go tool asm`.
+// in MinLC (4) units; byte-identical to `go tool asm`.
 func TestLOONG64_pcsp(t *testing.T) {
 	cases := []struct {
 		name string

asm/loong64_reloc_test.go

@@ -0,0 +1,42 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+package asm
+
+import (
+	"testing"
+
+	"sourcedock.dev/petrbalvin/gasm-devkit/parser"
+)
+
+// TestLOONG64RelocOffsetsIncludePrologue pins the function-relative
+// relocation offsets of a framed loong64 function: the offsets used to
+// exclude the prologue, so every relocation landed on a prologue
+// instruction in the GOOBJ/ELF output.
+func TestLOONG64RelocOffsetsIncludePrologue(t *testing.T) {
+	f, errs := parser.Parse("k_loong64.s", "TEXT \u00b7f(SB), $16-0\n"+
+		"\tMOVV $gdata(SB), R4\n"+
+		"\tRET\n"+
+		"GLOBL gdata(SB), $8\n")
+	if len(errs) > 0 {
+		t.Fatalf("parse: %v", errs)
+	}
+	img, err := AssembleFileLOONG64(f)
+	if err != nil {
+		t.Fatalf("assemble: %v", err)
+	}
+	fn := img.Funcs[0]
+
+	// Layout: 12-byte prologue (autosize 32), pcalau12i+addi.d (12, 16),
+	// epilogue with RET.
+	if len(fn.Relocs) != 2 {
+		t.Fatalf("relocs = %d, want 2", len(fn.Relocs))
+	}
+	hi, lo := fn.Relocs[0], fn.Relocs[1]
+	if hi.Kind != RelLoong64AddrHi || hi.Off != 12 || hi.After != 12 {
+		t.Errorf("hi reloc = {off %d after %d kind %d}, want {off 12 after 12 kind RelLoong64AddrHi}", hi.Off, hi.After, hi.Kind)
+	}
+	if lo.Kind != RelLoong64AddrLo || lo.Off != 16 || lo.After != 16 {
+		t.Errorf("lo reloc = {off %d after %d kind %d}, want {off 16 after 16 kind RelLoong64AddrLo}", lo.Off, lo.After, lo.Kind)
+	}
+}

asm/reg.go

@@ -12,33 +12,33 @@ import "maps"
 import "strings"
 
 // Reg is an x86-64 register.  In Plan 9 assembly the classic names (AX, BX, …)
-// are size-agnostic — the instruction suffix (MOVQ vs MOVL) fixes the width —
+// are size-agnostic, the instruction suffix (MOVQ vs MOVL) fixes the width
 // so the encoder keys off the register's index and lets the mnemonic supply the
 // size.  The high flag marks the legacy high-byte registers AH/CH/DH/BH, which
-// occupy indices 4–7 yet take no REX prefix, unlike SPL/BPL/SIL/DIL that share
+// occupy indices 4-7 yet take no REX prefix, unlike SPL/BPL/SIL/DIL that share
 // those indices but require one.  The mask flag marks the AVX-512 opmask
-// registers K0–K7.
+// registers K0-K7.
 type Reg struct {
 	idx  int
 	size int  // informational width implied by the name; the mnemonic decides
 	high bool // AH/CH/DH/BH
-	mask bool // K0–K7 opmask register
+	mask bool // K0-K7 opmask register
 }
 
-// Index returns the register number (0–15 for GPRs, 0–31 for vectors).
+// Index returns the register number (0-15 for GPRs, 0-31 for vectors).
 func (r Reg) Index() int { return r.idx }
 
 // Size returns the width in bytes implied by the register's name.
 func (r Reg) Size() int { return r.size }
 
-// IsMask reports whether r is an AVX-512 opmask register (K0–K7).
+// IsMask reports whether r is an AVX-512 opmask register (K0-K7).
 func (r Reg) IsMask() bool { return r.mask }
 
 func (r Reg) isOperand() {}
 
 // needsREX reports whether this register forces a REX prefix at the given
-// operand size: the extended registers R8–R15 always do, and at byte size the
+// operand size: the extended registers R8-R15 always do, and at byte size the
-// low registers SPL/BPL/SIL/DIL (indices 4–7, not high) do as well.
+// low registers SPL/BPL/SIL/DIL (indices 4-7, not high) do as well.
 func (r Reg) needsREX(opSize int) bool {
 	if r.idx >= 8 {
 		return true
@@ -133,7 +133,7 @@ func buildRegByName() map[string]Reg {
 	}
 
 	// Vector: X0..X31 (128-bit, size 16), Y0..Y31 (256-bit, size 32),
-	// Z0..Z31 (512-bit, size 64).  Indices 16–31 are only encodable in EVEX
+	// Z0..Z31 (512-bit, size 64).  Indices 16-31 are only encodable in EVEX
 	// (AVX-512) instructions; the encoder validates that through its tables.
 	for i := 0; i <= 31; i++ {
 		m["X"+itoa(i)] = Reg{idx: i, size: 16}

asm/riscv_assemble.go

@@ -15,14 +15,16 @@ import (
 func assembleRISCV(t *ast.Text) ([]byte, map[string]int, []Reloc, []LineEntry, []SpadjStep, error) {
 	fi := riscvComputeFrame(t)
 	prologue := riscvPrologue(fi)
+	guardLen := riscvGuardLen(fi)
 
 	var relocs []Reloc
 	var spadj []SpadjStep
 
 	// The prologue raises the SP delta by autosize; the boundary is reported
 	// at the pc just past its ADDI, exactly as the toolchain's pctospadj does.
+	// The guard prefix shifts its PC.
 	if fi.autosize != 0 {
-		spadj = append(spadj, SpadjStep{PC: riscvPrologueSpadjPC(fi), Value: fi.autosize})
+		spadj = append(spadj, SpadjStep{PC: guardLen + riscvPrologueSpadjPC(fi), Value: fi.autosize})
 	}
 
 	// Pass 1: collect instructions and compute label offsets assuming 4 bytes
@@ -34,7 +36,7 @@ func assembleRISCV(t *ast.Text) ([]byte, map[string]int, []Reloc, []LineEntry, [
 	}
 	var recs []instrRec
 	offsets := map[string]int{}
-	pos := len(prologue)
+	pos := guardLen + len(prologue)
 	for _, stmt := range t.Body {
 		switch s := stmt.(type) {
 		case *ast.Label:
@@ -66,7 +68,7 @@ func assembleRISCV(t *ast.Text) ([]byte, map[string]int, []Reloc, []LineEntry, [
 
 	// Pass 4: recompute offsets with actual sizes.
 	offsets = map[string]int{}
-	pos = len(prologue)
+	pos = guardLen + len(prologue)
 	for _, stmt := range t.Body {
 		switch s := stmt.(type) {
 		case *ast.Label:
@@ -82,9 +84,17 @@ func assembleRISCV(t *ast.Text) ([]byte, map[string]int, []Reloc, []LineEntry, [
 	}
 
 	// Pass 5: re-encode branches with corrected offsets.  Record relocations
-	// during this final pass (relocation offsets are relative to instruction start).
+	// during this final pass (relocation offsets are relative to instruction
-	out := append([]byte(nil), prologue...)
+	// start).  The guard prefix precedes the prologue; its branches target
-	pc = len(prologue)
+	// the morestack block at the end of the function, which the previous
+	// passes have sized.
+	var out []byte
+	guardBytes, guardReloc := riscvGuard(fi)
+	if fi.needSplit {
+		out = append(out, guardBytes...)
+	}
+	out = append(out, prologue...)
+	pc = guardLen + len(prologue)
 	preCount := len(relocs)
 	var lines []LineEntry
 	for _, r := range recs {
@@ -119,9 +129,49 @@ func assembleRISCV(t *ast.Text) ([]byte, map[string]int, []Reloc, []LineEntry, [
 			pc += len(code)
 		}
 	}
+	if fi.needSplit {
+		relocs = append(relocs, guardReloc)
+	}
 	return out, offsets, relocs, lines, spadj, nil
 }
 
+// riscvImmAlias maps the R-type ALU mnemonics onto their I-type immediate
+// forms: the toolchain accepts ADD $imm, rj, rd and emits addi.  Applied
+// whenever the first operand is an immediate.
+var riscvImmAlias = map[string]string{
+	"ADD":  "ADDI",
+	"ADDW": "ADDIW",
+	"AND":  "ANDI",
+	"OR":   "ORI",
+	"XOR":  "XORI",
+	"SLL":  "SLLI",
+	"SRL":  "SRLI",
+	"SRA":  "SRAI",
+	"SLLW": "SLLIW",
+	"SRLW": "SRLIW",
+	"SRAW": "SRAIW",
+}
+
+// riscvNormaliseImmAlias rewrites the mnemonic to its immediate form when the
+// first operand is an immediate: the toolchain accepts ADD $imm, rj, rd and
+// emits addi, and SUB $imm becomes addi with the negated immediate.  The
+// second result reports that negation; the operand itself is left untouched
+// because several passes normalise the same instruction.
+func riscvNormaliseImmAlias(mnem string, ops []*ast.Operand) (string, bool) {
+	if len(ops) >= 2 && isImmOperand(ops[0]) {
+		switch strings.ToUpper(mnem) {
+		case "SUB":
+			return "ADDI", true
+		case "SUBW":
+			return "ADDIW", true
+		}
+		if alias, ok := riscvImmAlias[strings.ToUpper(mnem)]; ok {
+			return alias, false
+		}
+	}
+	return mnem, false
+}
+
 // riscvInstrSize returns the encoded size in bytes of a RISC-V instruction.
 // Most instructions are 4 bytes; MOV with a large immediate and I-type
 // arithmetic with a large immediate expand to several (possibly compressed)
@@ -129,10 +179,12 @@ func assembleRISCV(t *ast.Text) ([]byte, map[string]int, []Reloc, []LineEntry, [
 func riscvInstrSize(instr *ast.Instr, fi riscvFrameInfo) int {
 	mnem := instr.Mnemonic.Text
 	ops := instr.Operands
+	var immNeg bool
+	mnem, immNeg = riscvNormaliseImmAlias(mnem, ops)
 	if mnem == "RET" {
 		return len(riscvReturn(fi))
 	}
-	if mnem == "MOV" && len(ops) == 2 {
+	if strings.HasPrefix(mnem, "MOV") && len(ops) == 2 {
 		// MOV $sym(SB), rd → 8 bytes (AUIPC + ADDI).
 		if isImmOperand(ops[0]) && ops[0].Imm.Sym != nil && ops[0].Imm.Sym.Pseudo == "SB" {
 			return 8
@@ -149,10 +201,22 @@ func riscvInstrSize(instr *ast.Instr, fi riscvFrameInfo) int {
 		if isImmOperand(ops[0]) && ops[0].Imm.Sym == nil {
 			return riscvMovImmSize(regFromOperand(ops[1]), immFromOperand(ops[0]))
 		}
+		// Frame-relative loads and stores: a frame offset beyond the signed
+		// 12-bit range materialises the address in X31 first.
+		if isMemOperand(ops[0]) && !isMemOperand(ops[1]) {
+			return riscvFrameMemSize(ops[0], fi)
+		}
+		if isMemOperand(ops[1]) && !isMemOperand(ops[0]) {
+			return riscvFrameMemSize(ops[1], fi)
+		}
 	}
 	// I-type arithmetic with a large immediate expands to several instructions.
 	if (mnem == "ADDI" || mnem == "ANDI" || mnem == "ORI" || mnem == "XORI") && len(ops) >= 1 && isImmOperand(ops[0]) {
-		return riscvItypeImmediateSize(mnem, immFromOperand(ops[0]))
+		imm := immFromOperand(ops[0])
+		if immNeg {
+			imm = -imm
+		}
+		return riscvItypeImmediateSize(mnem, imm)
 	}
 	return 4
 }
@@ -171,6 +235,8 @@ func isBranchLike(mnem string) bool {
 func encodeRISCVInstr(instr *ast.Instr, pc int, offsets map[string]int, fi riscvFrameInfo, relocs *[]Reloc) ([]byte, error) {
 	mnem := instr.Mnemonic.Text
 	ops := instr.Operands
+	var immNeg bool
+	mnem, immNeg = riscvNormaliseImmAlias(mnem, ops)
 	var word uint32
 
 	// Handle pseudo-instructions and special cases first.
@@ -187,19 +253,51 @@ func encodeRISCVInstr(instr *ast.Instr, pc int, offsets map[string]int, fi riscv
 		}
 		op := ops[0]
 		if op.Addr.Sym == nil || op.Addr.Sym.Pseudo != "SB" {
+			// CALL (X5): an indirect call, the toolchain's JALR X1, 0(X5).
+			if op.Addr.Sym == nil && op.Addr.Base != "" {
+				if op.Addr.Offset != 0 || op.Addr.Index != "" {
+					return nil, fmt.Errorf("CALL: invalid indirect operand %q", op.Raw)
+				}
+				rs1 := riscvRegNum(op.Addr.Base)
+				if rs1 < 0 {
+					return nil, fmt.Errorf("CALL: unknown branch register %q", op.Addr.Base)
+				}
+				word = riscvIType(riscvEnc{0x67, 0x0, 0x00}, 1, rs1, 0)
+				return []byte{byte(word), byte(word >> 8), byte(word >> 16), byte(word >> 24)}, nil
+			}
 			return nil, fmt.Errorf("CALL: local branch target is not supported (use CALL sym(SB))")
 		}
 		if relocs != nil {
 			*relocs = append(*relocs, Reloc{Off: 0, After: 4, Name: op.Addr.Sym.Name, Kind: RelRISCVJal, Addend: op.Addr.Sym.Offset})
 		}
-		word = riscvJType(1, 0) // JAL X1, 0 — the linker fills the offset
+		word = riscvJType(1, 0) // JAL X1, 0, the linker fills the offset
 		return []byte{byte(word), byte(word >> 8), byte(word >> 16), byte(word >> 24)}, nil
 	case "JMP":
 		// JMP = JAL X0, target.  The Go assembler never compresses this to
 		// C.J, so always emit the 32-bit JAL.
 		var target string
 		if len(ops) >= 1 {
+			// JMP sym(SB): a tail call, JAL X0 against a symbol relocation.
+			if ops[0].Addr.Sym != nil && ops[0].Addr.Sym.Pseudo == "SB" {
+				if relocs != nil {
+					*relocs = append(*relocs, Reloc{Off: 0, After: 4, Name: ops[0].Addr.Sym.Name, Kind: RelRISCVJal, Addend: ops[0].Addr.Sym.Offset})
+				}
+				word = riscvJType(0, 0)
+				return []byte{byte(word), byte(word >> 8), byte(word >> 16), byte(word >> 24)}, nil
+			}
 			target = labelFromOperand(ops[0])
+			// JMP (X5): an indirect branch, the toolchain's JALR X0, 0(X5).
+			if ops[0].Addr.Sym == nil && ops[0].Addr.Base != "" {
+				if ops[0].Addr.Offset != 0 || ops[0].Addr.Index != "" {
+					return nil, fmt.Errorf("JMP: invalid indirect operand %q", ops[0].Raw)
+				}
+				rs1 := riscvRegNum(ops[0].Addr.Base)
+				if rs1 < 0 {
+					return nil, fmt.Errorf("JMP: unknown branch register %q", ops[0].Addr.Base)
+				}
+				word = riscvIType(riscvEnc{0x67, 0x0, 0x00}, 0, rs1, 0)
+				return []byte{byte(word), byte(word >> 8), byte(word >> 16), byte(word >> 24)}, nil
+			}
 		}
 		targetOff, ok := offsets[target]
 		if !ok {
@@ -226,14 +324,50 @@ func encodeRISCVInstr(instr *ast.Instr, pc int, offsets map[string]int, fi riscv
 		return []byte{byte(word), byte(word >> 8), byte(word >> 16), byte(word >> 24)}, nil
 
 	// MOV is a pseudo-instruction that the Go assembler uses for loads,
-	// stores, register moves and immediate loads.
+	// stores, register moves and immediate loads.  The width suffixes
-	case "MOV":
+	// (MOVB/MOVH/MOVW and unsigned forms) select the access width, and
+	// MOVD/MOVF address the FP registers.
+	case "MOV", "MOVB", "MOVBU", "MOVH", "MOVHU", "MOVW", "MOVWU", "MOVF", "MOVD":
 		return encodeRISCVMov(instr, fi, relocs)
 
 	// JALR: indirect jump/call.  Plan 9: JALR rs1, rd or JALR offset(rs1).
 	case "JALR":
 		return encodeRISCVJALR(instr, fi)
 
+	// Branch-zero pseudos: BEQZ/BNEZ compare against X0, and BLTZ/BGEZ/
+	// BLEZ/BGTZ reorder the register operands of BLT/BGE accordingly.
+	case "BEQZ", "BNEZ", "BLTZ", "BGEZ", "BLEZ", "BGTZ":
+		if len(ops) != 2 {
+			return nil, fmt.Errorf("%s expects 2 operands, got %d", mnem, len(ops))
+		}
+		rs := regFromOperand(ops[0])
+		if rs < 0 {
+			return nil, fmt.Errorf("%s: invalid register", mnem)
+		}
+		target := labelFromOperand(ops[1])
+		targetOff, ok := offsets[target]
+		if !ok {
+			return nil, fmt.Errorf("undefined label %q%s", target, suggestLabel(target, offsets))
+		}
+		var enc riscvEnc
+		rs1, rs2 := rs, 0
+		switch mnem {
+		case "BEQZ":
+			enc = riscvEnc{0x63, 0x0, 0x00} // beq rs, x0
+		case "BNEZ":
+			enc = riscvEnc{0x63, 0x1, 0x00} // bne rs, x0
+		case "BLTZ":
+			enc = riscvEnc{0x63, 0x4, 0x00} // blt rs, x0
+		case "BGEZ":
+			enc = riscvEnc{0x63, 0x5, 0x00} // bge rs, x0
+		case "BLEZ":
+			enc, rs1, rs2 = riscvEnc{0x63, 0x5, 0x00}, 0, rs // bge x0, rs
+		case "BGTZ":
+			enc, rs1, rs2 = riscvEnc{0x63, 0x4, 0x00}, 0, rs // blt x0, rs
+		}
+		word = riscvBType(enc, rs1, rs2, int32(targetOff-pc))
+		return []byte{byte(word), byte(word >> 8), byte(word >> 16), byte(word >> 24)}, nil
+
 	// System instructions with no operands.
 	case "FENCE", "ECALL", "EBREAK":
 		enc, ok := riscvInstrTable[mnem]
@@ -395,7 +529,7 @@ func encodeRISCVInstr(instr *ast.Instr, pc int, offsets map[string]int, fi riscv
 		}
 		word = riscvSType(enc, rs1, rs2, imm)
 
-	// LR (load-reserved): INSTR (addr), dst — 2 operands.
+	// LR (load-reserved): INSTR (addr), dst, 2 operands.
 	case len(ops) == 2 && isLRInstr(mnem):
 		rs1, _ := memFromOperandWithFrame(ops[0], fi)
 		rd := regFromOperand(ops[1])
@@ -404,7 +538,7 @@ func encodeRISCVInstr(instr *ast.Instr, pc int, offsets map[string]int, fi riscv
 		}
 		word = riscvAMOType(enc, rd, rs1, 0) // rs2=0 for LR
 
-	// SC (store-conditional): INSTR src, (addr), dst — 3 operands.
+	// SC (store-conditional): INSTR src, (addr), dst, 3 operands.
 	case len(ops) == 3 && isSCInstr(mnem):
 		rs2 := regFromOperand(ops[0])
 		rs1, _ := memFromOperandWithFrame(ops[1], fi)
@@ -428,6 +562,9 @@ func encodeRISCVInstr(instr *ast.Instr, pc int, offsets map[string]int, fi riscv
 	// two-operand form INSTR $imm, rd uses rd as the source.
 	case len(ops) == 3 && isITypeInstr(mnem):
 		imm := immFromOperand(ops[0]) // immediate
+		if immNeg {
+			imm = -imm // SUB $imm arrived through the ADDI alias
+		}
 		rs1 := regFromOperand(ops[1]) // source register
 		rd := regFromOperand(ops[2])  // destination
 		if rd < 0 || rs1 < 0 {
@@ -437,13 +574,16 @@ func encodeRISCVInstr(instr *ast.Instr, pc int, offsets map[string]int, fi riscv
 
 	case len(ops) == 2 && isITypeInstr(mnem):
 		imm := immFromOperand(ops[0])
+		if immNeg {
+			imm = -imm
+		}
 		rd := regFromOperand(ops[1])
 		if rd < 0 {
 			return nil, fmt.Errorf("invalid register in %s", mnem)
 		}
 		return encodeRISCVItypeImmediate(mnem, enc, rd, rd, imm)
 
-	// Loads: rd, offset(rs1) — Plan 9 order is LD src, dst.
+	// Loads: rd, offset(rs1), Plan 9 order is LD src, dst.
 	case len(ops) == 2 && isLoadInstr(mnem):
 		rd := regFromOperand(ops[1])                    // destination (last operand)
 		rs1, imm := memFromOperandWithFrame(ops[0], fi) // memory source (first operand)
@@ -538,7 +678,7 @@ func encodeRISCVMov(instr *ast.Instr, fi riscvFrameInfo, relocs *[]Reloc) ([]byt
 
 	// Immediate → register.
 	if isImmOperand(src) {
-		// MOV $sym(SB), rd — load address of a static symbol or external.
+		// MOV $sym(SB), rd, load address of a static symbol or external.
 		if src.Imm.Sym != nil && src.Imm.Sym.Pseudo == "SB" {
 			rd := regFromOperand(dst)
 			if rd < 0 {
@@ -546,7 +686,7 @@ func encodeRISCVMov(instr *ast.Instr, fi riscvFrameInfo, relocs *[]Reloc) ([]byt
 			}
 			return encodeRISCVSBAddr(src.Imm.Sym, rd, relocs), nil
 		}
-		// MOV $sym(FP/SP), rd — not supported: immediate symbol references
+		// MOV $sym(FP/SP), rd, not supported: immediate symbol references
 		// other than SB cannot be encoded as a simple immediate.
 		if src.Imm.Sym != nil && src.Imm.Sym.Pseudo != "" {
 			return nil, fmt.Errorf("MOV $%s(%s): unsupported immediate symbol reference (only SB is supported)", src.Imm.Sym.Name, src.Imm.Sym.Pseudo)
@@ -562,7 +702,7 @@ func encodeRISCVMov(instr *ast.Instr, fi riscvFrameInfo, relocs *[]Reloc) ([]byt
 	// Memory → register (load).
 	if isMemOperand(src) && !isMemOperand(dst) {
 		rd := regFromOperand(dst)
-		// MOV sym(SB), rd — load from static data.
+		// MOV sym(SB), rd, load from static data.
 		if src.Addr.Sym != nil && src.Addr.Sym.Pseudo == "SB" {
 			if rd < 0 {
 				return nil, fmt.Errorf("MOV sym(SB): invalid destination register")
@@ -573,14 +713,13 @@ func encodeRISCVMov(instr *ast.Instr, fi riscvFrameInfo, relocs *[]Reloc) ([]byt
 		if rd < 0 || rs1 < 0 {
 			return nil, fmt.Errorf("MOV load: invalid operand")
 		}
-		word := riscvIType(riscvEnc{0x03, 0x3, 0x00}, rd, rs1, off)
+		return riscvFrameMemOp(riscvMovEnc(strings.ToUpper(instr.Mnemonic.Text), false), false, rd, rs1, off), nil
-		return []byte{byte(word), byte(word >> 8), byte(word >> 16), byte(word >> 24)}, nil
 	}
 
 	// Register → memory (store).
 	if !isMemOperand(src) && isMemOperand(dst) {
 		rs2 := regFromOperand(src)
-		// MOV rd, sym(SB) — store to static data.
+		// MOV rd, sym(SB), store to static data.
 		if dst.Addr.Sym != nil && dst.Addr.Sym.Pseudo == "SB" {
 			if rs2 < 0 {
 				return nil, fmt.Errorf("MOV rd, sym(SB): invalid source register")
@@ -591,22 +730,108 @@ func encodeRISCVMov(instr *ast.Instr, fi riscvFrameInfo, relocs *[]Reloc) ([]byt
 		if rs2 < 0 || rs1 < 0 {
 			return nil, fmt.Errorf("MOV store: invalid operand")
 		}
-		word := riscvSType(riscvEnc{0x23, 0x3, 0x00}, rs1, rs2, off)
+		return riscvFrameMemOp(riscvMovEnc(strings.ToUpper(instr.Mnemonic.Text), true), true, rs2, rs1, off), nil
-		return []byte{byte(word), byte(word >> 8), byte(word >> 16), byte(word >> 24)}, nil
 	}
 
-	// Register → register (ADDI $0, src, dst).
+	// Register → register: MOVD/MOVF are FP moves (fsgnj with rs2 = rs1),
+	// everything else is ADDI $0, src, dst.
 	{
 		rs1 := regFromOperand(src)
 		rd := regFromOperand(dst)
 		if rd < 0 || rs1 < 0 {
 			return nil, fmt.Errorf("MOV: invalid register operand")
 		}
+		mnem := strings.ToUpper(instr.Mnemonic.Text)
+		if mnem == "MOVD" || mnem == "MOVF" {
+			op := uint32(0x20000053) // FSGNJ.S
+			if mnem == "MOVD" {
+				op = 0x22000053 // FSGNJ.D
+			}
+			return wordLE(op | uint32(rs1)<<15 | uint32(rs1)<<20 | uint32(rd)<<7), nil
+		}
 		word := riscvIType(riscvEnc{0x13, 0x0, 0x00}, rd, rs1, 0)
 		return []byte{byte(word), byte(word >> 8), byte(word >> 16), byte(word >> 24)}, nil
 	}
 }
 
+// riscvMovEnc returns the load (store=false) or store (store=true) opcode for
+// a MOV-family mnemonic: the suffix selects the access width, MOVD and MOVF
+// select the FP load/store opcodes, and bare MOV is the 64-bit integer form.
+func riscvMovEnc(mnem string, store bool) riscvEnc {
+	if store {
+		switch mnem {
+		case "MOVB":
+			return riscvEnc{0x23, 0x0, 0x00} // SB
+		case "MOVH":
+			return riscvEnc{0x23, 0x1, 0x00} // SH
+		case "MOVW":
+			return riscvEnc{0x23, 0x2, 0x00} // SW
+		case "MOVF":
+			return riscvEnc{0x27, 0x2, 0x00} // FSW
+		case "MOVD":
+			return riscvEnc{0x27, 0x3, 0x00} // FSD
+		}
+		return riscvEnc{0x23, 0x3, 0x00} // SD
+	}
+	switch mnem {
+	case "MOVB":
+		return riscvEnc{0x03, 0x0, 0x00} // LB
+	case "MOVBU":
+		return riscvEnc{0x03, 0x4, 0x00} // LBU
+	case "MOVH":
+		return riscvEnc{0x03, 0x1, 0x00} // LH
+	case "MOVHU":
+		return riscvEnc{0x03, 0x5, 0x00} // LHU
+	case "MOVW":
+		return riscvEnc{0x03, 0x2, 0x00} // LW
+	case "MOVWU":
+		return riscvEnc{0x03, 0x6, 0x00} // LWU
+	case "MOVF":
+		return riscvEnc{0x07, 0x2, 0x00} // FLW
+	case "MOVD":
+		return riscvEnc{0x07, 0x3, 0x00} // FLD
+	}
+	return riscvEnc{0x03, 0x3, 0x00} // LD
+}
+
+// riscvFrameMemOp encodes a register-relative load (store=false, I-type
+// width 0x03) or store (store=true, S-type width 0x23) of the 64-bit width
+// at off(rs1).  Offsets beyond the signed 12-bit range materialise the
+// address in X31 first: LUI hi (the rounding split), then ADD X31, rs1,
+// matching the toolchain's large-frame addressing; the access uses the
+// sign-extended low part, which always fits.
+func riscvFrameMemOp(enc riscvEnc, store bool, reg, rs1 int, off int32) []byte {
+	if fits12(off) {
+		var word uint32
+		if store {
+			word = riscvSType(enc, rs1, reg, off)
+		} else {
+			word = riscvIType(enc, reg, rs1, off)
+		}
+		return []byte{byte(word), byte(word >> 8), byte(word >> 16), byte(word >> 24)}
+	}
+	lo := off - (splitHi(off) << 12)
+	out := riscvAddressInX31WithBase(off, rs1)
+	var word uint32
+	if store {
+		word = riscvSType(enc, 31, reg, lo)
+	} else {
+		word = riscvIType(enc, reg, 31, lo)
+	}
+	return append(out, wordLE(word)...)
+}
+
+// riscvFrameMemSize returns the encoded size of a frame-relative MOV for the
+// layout pass: 4 bytes when the offset fits, otherwise the X31
+// materialisation plus the access.
+func riscvFrameMemSize(op *ast.Operand, fi riscvFrameInfo) int {
+	rs1, off := memFromOperandWithFrame(op, fi)
+	if fits12(off) {
+		return 4
+	}
+	return len(riscvAddressInX31WithBase(off, rs1)) + 4
+}
+
 // encodeRISCVLoadImm encodes loading an immediate into a register (MOV $imm,
 // rd), matching the toolchain's instructionsForMOVConst.  For 12-bit
 // immediates it emits ADDI $imm, ZERO, rd (compressed to C.LI when it fits
@@ -821,25 +1046,34 @@ func word16(w uint16) []byte {
 }
 
 // encodeRISCVJALR encodes the JALR indirect jump/call instruction.
-// Plan 9: JALR rs1, rd  (2 regs) or JALR offset(rs1) (memory → rd=X1).
+// Plan 9: JALR rs1, rd  (2 regs), JALR rd, offset(rs1)  (the trampoline
+// form), or JALR offset(rs1) (memory → rd=X1).
 func encodeRISCVJALR(instr *ast.Instr, fi riscvFrameInfo) ([]byte, error) {
 	ops := instr.Operands
+	// JALR rd, offset(rs1): the memory operand's base is the jump-target
+	// register, not the destination.
+	if len(ops) == 2 && isMemOperand(ops[1]) {
+		rd := regFromOperand(ops[0])
+		rs1, imm := memFromOperandWithFrame(ops[1], fi)
+		if rd < 0 || rs1 < 0 {
+			return nil, fmt.Errorf("JALR: invalid register operand")
+		}
+		return wordLE(riscvIType(riscvEnc{0x67, 0x0, 0x00}, rd, rs1, imm)), nil
+	}
 	if len(ops) == 2 {
 		rs1 := regFromOperand(ops[0])
 		rd := regFromOperand(ops[1])
 		if rd < 0 || rs1 < 0 {
 			return nil, fmt.Errorf("JALR: invalid register operand")
 		}
-		word := riscvIType(riscvEnc{0x67, 0x0, 0x00}, rd, rs1, 0)
+		return wordLE(riscvIType(riscvEnc{0x67, 0x0, 0x00}, rd, rs1, 0)), nil
-		return wordLE(word), nil
 	}
 	if len(ops) == 1 {
 		rs1, imm := memFromOperandWithFrame(ops[0], fi)
 		if rs1 < 0 {
 			return nil, fmt.Errorf("JALR: invalid memory operand")
 		}
-		word := riscvIType(riscvEnc{0x67, 0x0, 0x00}, 1, rs1, imm)
+		return wordLE(riscvIType(riscvEnc{0x67, 0x0, 0x00}, 1, rs1, imm)), nil
-		return wordLE(word), nil
 	}
 	return nil, fmt.Errorf("JALR expects 1 or 2 operands, got %d", len(ops))
 }
@@ -1006,7 +1240,7 @@ func tryCompressRVC(instr *ast.Instr, fi riscvFrameInfo) (uint16, bool) {
 		}
 
 	case "ADDW", "SUBW":
-		// C.ADDW (0x27,1) / C.SUBW (0x27,0) — CA-type, prime regs.
+		// C.ADDW (0x27,1) / C.SUBW (0x27,0), CA-type, prime regs.
 		if len(ops) == 3 {
 			funct2 := uint32(0x0)
 			if mnem == "ADDW" {
@@ -1314,7 +1548,7 @@ func suggestLabel(target string, offsets map[string]int) string {
 	}
 	// Only suggest if the distance is small enough.
 	if bestDist <= 3 && bestDist < len(target)/2+1 {
-		return fmt.Sprintf(" — did you mean %q?", best)
+		return fmt.Sprintf("; did you mean %q?", best)
 	}
 	return ""
 }

asm/riscv_encode.go

@@ -154,7 +154,7 @@ type riscvEnc struct {
 
 // riscvInstrTable maps RISC-V mnemonics to their encoding.
 var riscvInstrTable = map[string]riscvEnc{
-	// RV64I — R-type arithmetic/logic.
+	// RV64I, R-type arithmetic/logic.
 	"ADD":  {0x33, 0x0, 0x00},
 	"SUB":  {0x33, 0x0, 0x20},
 	"SLL":  {0x33, 0x1, 0x00},
@@ -165,20 +165,20 @@ var riscvInstrTable = map[string]riscvEnc{
 	"SRA":  {0x33, 0x5, 0x20},
 	"OR":   {0x33, 0x6, 0x00},
 	"AND":  {0x33, 0x7, 0x00},
-	// RV64I — 32-bit variants (W suffix).
+	// RV64I, 32-bit variants (W suffix).
 	"ADDW": {0x3B, 0x0, 0x00},
 	"SUBW": {0x3B, 0x0, 0x20},
 	"SLLW": {0x3B, 0x1, 0x00},
 	"SRLW": {0x3B, 0x5, 0x00},
 	"SRAW": {0x3B, 0x5, 0x20},
-	// RV64I — I-type shift-immediate (shamt in rs2 field).
+	// RV64I, I-type shift-immediate (shamt in rs2 field).
 	"SLLI":  {0x13, 0x1, 0x00},
 	"SRLI":  {0x13, 0x5, 0x00},
 	"SRAI":  {0x13, 0x5, 0x20},
 	"SLLIW": {0x1B, 0x1, 0x00},
 	"SRLIW": {0x1B, 0x5, 0x00},
 	"SRAIW": {0x1B, 0x5, 0x20},
-	// RV64M — multiply/divide.
+	// RV64M, multiply/divide.
 	"MUL":    {0x33, 0x0, 0x01},
 	"MULH":   {0x33, 0x1, 0x01},
 	"MULHSU": {0x33, 0x2, 0x01},
@@ -187,13 +187,13 @@ var riscvInstrTable = map[string]riscvEnc{
 	"DIVU":   {0x33, 0x5, 0x01},
 	"REM":    {0x33, 0x6, 0x01},
 	"REMU":   {0x33, 0x7, 0x01},
-	// RV64M — 32-bit variants.
+	// RV64M, 32-bit variants.
 	"MULW":  {0x3B, 0x0, 0x01},
 	"DIVW":  {0x3B, 0x4, 0x01},
 	"DIVUW": {0x3B, 0x5, 0x01},
 	"REMW":  {0x3B, 0x6, 0x01},
 	"REMUW": {0x3B, 0x7, 0x01},
-	// RV64I — I-type arithmetic.
+	// RV64I, I-type arithmetic.
 	"ADDI":  {0x13, 0x0, 0x00},
 	"ADDIW": {0x1B, 0x0, 0x00},
 	"SLTI":  {0x13, 0x2, 0x00},
@@ -228,10 +228,10 @@ var riscvInstrTable = map[string]riscvEnc{
 	"ECALL":  {0x73, 0x0, 0x00},
 	"EBREAK": {0x73, 0x0, 0x00},
 	"FENCE":  {0x0F, 0x0, 0x00},
-	// JALR — indirect jump/call (I-type).
+	// JALR, indirect jump/call (I-type).
 	"JALR": {0x67, 0x0, 0x00},
 
-	// RV64A — atomics (AMO opcode 0x2F).
+	// RV64A, atomics (AMO opcode 0x2F).
 	// funct3: 0x2 = word, 0x3 = doubleword. funct5 in bits [31:27].
 	"AMOSWAPW": {0x2F, 0x2, 0x01 << 2},
 	"AMOSWAPD": {0x2F, 0x3, 0x01 << 2},
@@ -252,7 +252,7 @@ var riscvInstrTable = map[string]riscvEnc{
 	"AMOMINUW": {0x2F, 0x2, 0x18 << 2},
 	"AMOMINUD": {0x2F, 0x3, 0x18 << 2},
 
-	// RV64F/D — floating-point arithmetic.
+	// RV64F/D, floating-point arithmetic.
 	"FADDS":  {0x53, 0x0, 0x00},
 	"FSUBS":  {0x53, 0x0, 0x04},
 	"FMULS":  {0x53, 0x0, 0x08},
@@ -274,13 +274,13 @@ var riscvInstrTable = map[string]riscvEnc{
 	"FMIND": {0x53, 0x0, 0x15},
 	"FMAXD": {0x53, 0x1, 0x15},
 
-	// RV64A — load-reserved / store-conditional (funct5 0x02 / 0x03).
+	// RV64A, load-reserved / store-conditional (funct5 0x02 / 0x03).
 	"LRW": {0x2F, 0x2, 0x02 << 2},
 	"LRD": {0x2F, 0x3, 0x02 << 2},
 	"SCW": {0x2F, 0x2, 0x03 << 2},
 	"SCD": {0x2F, 0x3, 0x03 << 2},
 
-	// FP compare — result in integer register (funct7 0x50/0x51).
+	// FP compare, result in integer register (funct7 0x50/0x51).
 	"FEQS": {0x53, 0x2, 0x50},
 	"FLTS": {0x53, 0x1, 0x50},
 	"FLES": {0x53, 0x0, 0x50},
@@ -328,6 +328,8 @@ var riscvCvtTable = map[string]riscvCvtEnc{
 	"FCVTSWU": {0x68, 0x1, 0x53}, // uint32 → float32
 	"FCVTSL":  {0x68, 0x2, 0x53}, // int64 → float32
 	"FCVTSLU": {0x68, 0x3, 0x53}, // uint64 → float32
+	"FCLASSS": {0x70, 0x0, 0x53}, // classify float32 → GPR mask
+	"FCLASSD": {0x70, 0x0, 0x53}, // classify float64 → GPR mask
 	"FCVTDW":  {0x69, 0x0, 0x53}, // int32 → float64
 	"FCVTDWU": {0x69, 0x1, 0x53}, // uint32 → float64
 	"FCVTDL":  {0x69, 0x2, 0x53}, // int64 → float64
@@ -442,10 +444,10 @@ func riscvJType(rd int, offset int32) uint32 {
 // ---- RVC (compressed) encoding helpers ----
 
 // isRVCIntReg reports whether a register number can be encoded in the 3-bit
-// prime register field used by compressed instructions (x8–x15).
+// prime register field used by compressed instructions (x8-x15).
 func isRVCIntReg(r int) bool { return r >= 8 && r <= 15 }
 
-// rvcReg3 returns the 3-bit encoding for registers x8–x15 (0–7).
+// rvcReg3 returns the 3-bit encoding for registers x8-x15 (0-7).
 func rvcReg3(r int) uint32 { return uint32(r - 8) }
 
 // rvcCR encodes a CR-type (register) compressed instruction.
@@ -455,7 +457,7 @@ func rvcCR(funct4, rd, rs2 uint32) uint16 {
 }
 
 // rvcCI encodes a CI-type (immediate) compressed instruction.
-// Used for C.ADDI, C.LI, C.LUI, C.ADDIW — linear 6-bit immediate.
+// Used for C.ADDI, C.LI, C.LUI, C.ADDIW, linear 6-bit immediate.
 func rvcCI(funct3, rd uint32, imm uint32) uint16 {
 	return uint16((funct3 << 13) | ((imm>>5)&1)<<12 | (rd << 7) | (imm&0x1F)<<2 | 0x1)
 }

asm/riscv_encode_test.go

@@ -289,7 +289,7 @@ TEXT ·cmp(SB), NOSPLIT, $0
 }
 
 func TestRISCV_forwardBranch(t *testing.T) {
-	// Forward label reference — must not fail.
+	// Forward label reference; must not fail.
 	fn := firstTextRISCV(t, `#include "textflag.h"
 TEXT ·fwd(SB), NOSPLIT, $0
 	ADDI $1, X10, X10
@@ -761,3 +761,24 @@ sub:
 		t.Error("expected error for CALL to local label, got nil")
 	}
 }
+
+// TestRISCVIndirectBranch pins the indirect branch encodings: JMP (X5) is the
+// toolchain's JALR X0, 0(X5), and the trampoline form JALR rd, offset(rs1)
+// takes its destination from the first operand (regression: the base
+// register was once read as the destination, silently jumping to X0).
+func TestRISCVIndirectBranch(t *testing.T) {
+	fn := firstTextRISCV(t, `#include "textflag.h"
+TEXT ·f(SB), NOSPLIT, $0-0
+	JMP (X5)
+	JALR X0, 0(X6)
+	JALR X28, 0(X9)
+	RET
+`)
+	code := assembleRISCVHelper(t, fn)
+	wantWords(t, code,
+		0x00028067, // jalr x0, 5(x0), 0
+		0x00030067, // jalr x0, 6(x0), 0
+		0x00048e67, // jalr x28, 9(x0), 0
+		0x00008067, // jalr x0, 1(x0), 0 (RET)
+	)
+}

asm/riscv_frame.go

@@ -32,6 +32,13 @@ import (
 // riscvFrameInfo holds the frame layout derived from a TEXT directive.
 type riscvFrameInfo struct {
 	autosize int // the real SP adjustment (locals + saved LR)
+
+	// Stack-split guard state: the toolchain emits the check for every
+	// non-NOSPLIT function whose autosize is nonzero (a zero autosize is
+	// "effectively NOSPLIT"); unlike amd64 and arm64 there is no leaf
+	// auto-NOSPLIT.
+	needSplit  bool
+	splitClass int // 0: <=StackSmall, 1: <=StackBig, 2: >StackBig
 }
 
 // riscvComputeFrame derives the frame layout for a TEXT function.
@@ -40,11 +47,34 @@ func riscvComputeFrame(t *ast.Text) riscvFrameInfo {
 	if frame != 0 || !riscvIsLeaf(t) {
 		// FixedFrameSize = 8: space for the saved link register.  A
 		// zero-frame non-leaf function still opens an 8-byte frame for LR.
-		return riscvFrameInfo{autosize: frame + 8}
+		autosize := frame + 8
+		fi := riscvFrameInfo{autosize: autosize}
+		if !hasNoSplitFlag(t) {
+			fi.needSplit = true
+			switch {
+			case autosize <= stackSmall:
+				fi.splitClass = 0
+			case autosize <= stackBig:
+				fi.splitClass = 1
+			default:
+				fi.splitClass = 2
+			}
+		}
+		return fi
 	}
 	return riscvFrameInfo{}
 }
 
+// hasNoSplitFlag reports whether the TEXT directive carries NOSPLIT.
+func hasNoSplitFlag(t *ast.Text) bool {
+	for _, f := range t.Flags {
+		if strings.EqualFold(f, "NOSPLIT") {
+			return true
+		}
+	}
+	return false
+}
+
 // riscvIsLeaf reports whether a function contains no call instructions.
 // CALL always links; JAL/JALR link only when their destination register is
 // the link register (X1), matching cmd/internal/obj/riscv's containsCall.
@@ -58,17 +88,24 @@ func riscvIsLeaf(t *ast.Text) bool {
 		case "CALL":
 			return false
 		case "JAL":
-			// JAL rd, target — a call only when rd is the link register.
+			// JAL rd, target, a call only when rd is the link register.
 			if len(in.Operands) >= 2 && regFromOperand(in.Operands[0]) == 1 {
 				return false
 			}
 		case "JALR":
-			// JALR rs1, rd — a call when rd is X1; JALR offset(rs1) always
+			// JALR rd, offset(rs1) links when the destination register (the
-			// links to X1.
+			// first operand) is X1; JALR rs1, rd links when the second
+			// register is X1; JALR offset(rs1) always links to X1.
 			if len(in.Operands) == 1 {
 				return false
 			}
-			if len(in.Operands) >= 2 && regFromOperand(in.Operands[1]) == 1 {
+			if isMemOperand(in.Operands[1]) {
+				if regFromOperand(in.Operands[0]) == 1 {
+					return false
+				}
+				continue
+			}
+			if regFromOperand(in.Operands[1]) == 1 {
 				return false
 			}
 		}
@@ -84,28 +121,99 @@ func riscvPrologue(fi riscvFrameInfo) []byte {
 		return nil
 	}
 	var out []byte
-	// MOV LR, -autosize(SP) — SD X1, -autosize(X2).  The negative offset is
+	// MOV LR, -autosize(SP), SD X1, -autosize(X2).  The negative offset is
-	// not compressible to C.SDSP (unsigned), so it stays 4 bytes.
+	// not compressible to C.SDSP (unsigned), so it stays 4 bytes.  Beyond
+	// the imm12 range the toolchain materialises the address in X31.
+	if fits12(int32(-fi.autosize)) {
 		out = append(out, wordLE(riscvSType(riscvEnc{0x23, 0x3, 0x00}, 2, 1, int32(-fi.autosize)))...)
-	// ADDI $-autosize, SP, SP — open the frame (C.ADDI when it fits).
+	} else {
+		out = append(out, riscvAddressInX31(int32(-fi.autosize))...)
+		lo := int32(-fi.autosize) - (splitHi(int32(-fi.autosize)) << 12)
+		out = append(out, wordLE(riscvSType(riscvEnc{0x23, 0x3, 0x00}, 31, 1, lo))...)
+	}
+	// ADDI $-autosize, SP, SP, open the frame (C.ADDI when it fits; X31
+	// materialisation beyond imm12).
+	if fits12(int32(-fi.autosize)) {
 		out = append(out, riscvSPAdjust(int32(-fi.autosize))...)
-	// MOV LR, 0(SP) — SD X1, 0(X2) → C.SDSP X1, 0.
+	} else {
+		out = append(out, riscvAddToSP(int32(-fi.autosize))...)
+	}
+	// MOV LR, 0(SP), SD X1, 0(X2) → C.SDSP X1, 0.
 	c := rvcSSP(0x7, 1, 0)
 	out = append(out, byte(c), byte(c>>8))
 	return out
 }
 
+func fits12(v int32) bool { return v >= -2048 && v <= 2047 }
+
+// splitHi returns the LUI half of the hi/lo split of v (what remains is the
+// sign-extended 12-bit low part).
+func splitHi(v int32) int32 {
+	_, high := splitRISCV32Imm(v)
+	return high
+}
+
+// riscvAddressInX31 materialises hi(v) into X31 against the stack pointer,
+// matching the toolchain's large-frame addressing: C.LUI (or LUI) X31, hi;
+// C.ADD (or ADD) X31, SP.
+func riscvAddressInX31(v int32) []byte {
+	return riscvAddressInX31WithBase(v, 2)
+}
+
+// riscvAddressInX31WithBase materialises hi(v) into X31 against an arbitrary
+// base register: LUI (or C.LUI) X31, hi; C.ADD X31, rs1.  The CR rs2 field
+// carries the full 5-bit register, so the compressed form is always
+// available.
+func riscvAddressInX31WithBase(v int32, rs1 int) []byte {
+	hi := splitHi(v)
+	var out []byte
+	if hi >= -32 && hi <= 31 {
+		c := rvcCI(0x3, 31, uint32(hi)&0x3F)
+		out = append(out, byte(c), byte(c>>8))
+	} else {
+		out = append(out, wordLE(riscvUType(riscvEnc{0x37, 0x0, 0x00}, 31, hi<<12))...)
+	}
+	c := rvcCR(0x9, 31, uint32(rs1))
+	return append(out, byte(c), byte(c>>8))
+}
+
+// riscvAddToSP adds v to SP through X31 for the values imm12 cannot carry:
+// C.LUI X31, hi; C.ADDIW X31, lo; C.ADD SP, X31 (the toolchain's form).
+func riscvAddToSP(v int32) []byte {
+	hi := splitHi(v)
+	lo := v - (hi << 12)
+	var out []byte
+	if hi >= -32 && hi <= 31 {
+		c := rvcCI(0x3, 31, uint32(hi)&0x3F)
+		out = append(out, byte(c), byte(c>>8))
+	} else {
+		out = append(out, wordLE(riscvUType(riscvEnc{0x37, 0x0, 0x00}, 31, hi<<12))...)
+	}
+	if lo >= -32 && lo <= 31 {
+		c := rvcCI(0x1, 31, uint32(lo)&0x3F)
+		out = append(out, byte(c), byte(c>>8))
+	} else {
+		out = append(out, wordLE(riscvIType(riscvEnc{0x1b, 0x0, 0x00}, 31, 31, lo))...)
+	}
+	c := rvcCR(0x9, 2, 31)
+	return append(out, byte(c), byte(c>>8))
+}
+
 // riscvReturn returns the bytes for a RET: the epilogue (restore LR and
 // deallocate the frame when present) followed by the uncompressed JALR X0,
 // 0(X1) the toolchain emits for RET (it never compresses RET to C.JR).
 func riscvReturn(fi riscvFrameInfo) []byte {
 	var out []byte
 	if fi.autosize != 0 {
-		// MOV 0(SP), LR — LD X1, 0(X2) → C.LDSP X1, 0.
+		// MOV 0(SP), LR, LD X1, 0(X2) → C.LDSP X1, 0.
 		c := rvcLSP(0x3, 1, 0)
 		out = append(out, byte(c), byte(c>>8))
-		// ADDI $autosize, SP, SP — close the frame (C.ADDI when it fits).
+		// ADDI $autosize, SP, SP, close the frame (C.ADDI when it fits).
+		if fits12(int32(fi.autosize)) {
 			out = append(out, riscvSPAdjust(int32(fi.autosize))...)
+		} else {
+			out = append(out, riscvAddToSP(int32(fi.autosize))...)
+		}
 	}
 	// JALR X0, 0(X1).
 	return append(out, wordLE(riscvIType(riscvEnc{0x67, 0x0, 0x00}, 0, 1, 0))...)
@@ -143,7 +251,7 @@ func riscvPrologueSpadjPC(fi riscvFrameInfo) int {
 }
 
 // riscvReturnEpilogueLen returns the byte length of the RET's epilogue up to
-// (but not including) the final JALR — the point where SP is restored.
+// (but not including) the final JALR, the point where SP is restored.
 func riscvReturnEpilogueLen(fi riscvFrameInfo) int {
 	if fi.autosize == 0 {
 		return 0
@@ -180,3 +288,74 @@ func riscvResolvePseudo(sym *ast.Symbol, fi riscvFrameInfo) (base int, off int32
 	}
 	return -1, 0
 }
+
+// riscvGuardLen returns the byte length of the stack-split guard prefix
+// including the inline morestack call (zero when the function needs no
+// guard).  Unlike amd64 and arm64, the toolchain places the morestack call
+// between the guard and the body: the guard branches forward over it.
+func riscvGuardLen(fi riscvFrameInfo) int {
+	_, reloc := riscvGuard(fi)
+	_ = reloc
+	return len(riscvGuardBytes(fi))
+}
+
+// riscvGuard emits the stack-split guard prefix with the inline morestack
+// call: the branch skips forward over JAL X5 and JAL X0 straight into the
+// body; the JAL X5 carries the R_RISCV_JAL relocation.  All offsets are
+// relative to the guard itself, which sits at function offset 0.
+func riscvGuard(fi riscvFrameInfo) ([]byte, Reloc) {
+	if !fi.needSplit {
+		return nil, Reloc{}
+	}
+	// MOV 16(g), X6 (g.stackguard0), g = X27.
+	out := wordLE(riscvIType(riscvEnc{0x03, 0x3, 0x00}, 6, 27, 16))
+	jalBack := func() []byte {
+		// JAL X0 back to the function start: it sits right after the JAL X5,
+		// so its displacement is minus the current offset.
+		return wordLE(riscvJType(0, int32(-len(out))))
+	}
+	var reloc Reloc
+	switch fi.splitClass {
+	case 0:
+		// BLTU X6, SP, done (+8: over the CALL and the JMP back)
+		out = append(out, wordLE(riscvBType(riscvEnc{0x63, 0x06, 0x00}, 6, 2, 12))...)
+		call := len(out)
+		reloc = Reloc{Off: call, After: call + 4, Name: "runtime\u00b7morestack_noctxt", Kind: RelRISCVJal}
+		out = append(out, wordLE(riscvJType(5, 0))...)
+		out = append(out, jalBack()...)
+	case 1:
+		// ADDI $-(framesize-StackSmall), SP, X7; BLTU X6, X7, done (+8)
+		off := int32(fi.autosize - stackSmall)
+		out = append(out, wordLE(riscvIType(riscvEnc{0x13, 0x0, 0x00}, 7, 2, -off))...)
+		out = append(out, wordLE(riscvBType(riscvEnc{0x63, 0x06, 0x00}, 6, 7, 12))...)
+		call := len(out)
+		reloc = Reloc{Off: call, After: call + 4, Name: "runtime\u00b7morestack_noctxt", Kind: RelRISCVJal}
+		out = append(out, wordLE(riscvJType(5, 0))...)
+		out = append(out, jalBack()...)
+	default:
+		// MOV $(framesize-StackSmall), X7; BLTU SP, X7, call;
+		// ADD $-(framesize-StackSmall), SP, X7; BLTU X6, X7, call
+		off := int32(fi.autosize - stackSmall)
+		mov := encodeRISCVLoadImm(7, off)
+		out = append(out, mov...)
+		addiLen := riscvItypeImmediateSize("ADDI", -off)
+		out = append(out, wordLE(riscvBType(riscvEnc{0x63, 0x06, 0x00}, 2, 7, int32(addiLen+8)))...)
+		addi, err := encodeRISCVItypeImmediate("ADDI", riscvEnc{0x13, 0x0, 0x00}, 7, 2, -off)
+		if err != nil {
+			addi = nil
+		}
+		out = append(out, addi...)
+		out = append(out, wordLE(riscvBType(riscvEnc{0x63, 0x06, 0x00}, 6, 7, 12))...)
+		call := len(out)
+		reloc = Reloc{Off: call, After: call + 4, Name: "runtime\u00b7morestack_noctxt", Kind: RelRISCVJal}
+		out = append(out, wordLE(riscvJType(5, 0))...)
+		out = append(out, jalBack()...)
+	}
+	return out, reloc
+}
+
+// riscvGuardBytes emits the guard prefix bytes alone (sizing helper).
+func riscvGuardBytes(fi riscvFrameInfo) []byte {
+	g, _ := riscvGuard(fi)
+	return g
+}

asm/vex.go

@@ -36,11 +36,11 @@ const (
 	vexNDS3Imm
 	// vexExtract is the lane-extract form `OP $imm, ysrc, xdst`: ModRM.reg =
 	// ysrc (op1), ModRM.rm = xdst or memory (op2), imm8 = op0.  The YMM
-	// source lives in the reg field, the destination in r/m — the PEXTR-style
+	// source lives in the reg field, the destination in r/m, the PEXTR-style
 	// layout.  VEXTRACTI128 and VEXTRACTF128 use this shape.
 	vexExtract
 	// vexRMRev is the reversed two-operand form `OP src, dst` with the source
-	// in ModRM.reg and the destination in r/m — the layout of the EVEX
+	// in ModRM.reg and the destination in r/m, the layout of the EVEX
 	// narrowing stores (VPMOVDW, VPMOVQD).
 	vexRMRev
 	// vexRMSrcLen is the two-operand conversion form `OP src, dst` whose
@@ -68,7 +68,7 @@ type vexSpec struct {
 // incrementally; every entry is covered by a byte-for-byte ground-truth test
 // against the Go assembler.
 var vexTable = map[string]vexSpec{
-	// VEX.128/256.66.0F.WIG — integer arithmetic / logic / compare.
+	// VEX.128/256.66.0F.WIG, integer arithmetic / logic / compare.
 	"VPADDD":      {1, 0xFE, 0, 1, -1, vexNDS3},
 	"VPADDQ":      {1, 0xD4, 0, 1, -1, vexNDS3},
 	"VPSUBD":      {1, 0xFA, 0, 1, -1, vexNDS3},
@@ -82,7 +82,7 @@ var vexTable = map[string]vexSpec{
 	"VPUNPCKHDQ":  {1, 0x6A, 0, 1, -1, vexNDS3},
 	"VPUNPCKLQDQ": {1, 0x6C, 0, 1, -1, vexNDS3},
 	"VPACKSSDW":   {1, 0x6B, 0, 1, -1, vexNDS3},
-	// VEX.256.66.0F38.W0 — dword permute (three-operand NDS form).
+	// VEX.256.66.0F38.W0, dword permute (three-operand NDS form).
 	"VPERMD": {2, 0x36, 0, 1, -1, vexNDS3},
 	// VEX.128/256.66.0F38.WIG.
 	"VPMULLD":  {2, 0x40, 0, 1, -1, vexNDS3},
@@ -90,14 +90,14 @@ var vexTable = map[string]vexSpec{
 	"VPSHUFB":  {2, 0x00, 0, 1, -1, vexNDS3},
 	"VPCMPGTQ": {2, 0x37, 0, 1, -1, vexNDS3},
 
-	// VEX.128/256.66.0F.WIG — packed double-precision arithmetic / logic.
+	// VEX.128/256.66.0F.WIG, packed double-precision arithmetic / logic.
 	"VADDPD": {1, 0x58, 0, 1, -1, vexNDS3},
 	"VMULPD": {1, 0x59, 0, 1, -1, vexNDS3},
 	"VSUBPD": {1, 0x5C, 0, 1, -1, vexNDS3},
 	"VDIVPD": {1, 0x5E, 0, 1, -1, vexNDS3},
 	"VMINPD": {1, 0x5D, 0, 1, -1, vexNDS3},
 	"VMAXPD": {1, 0x5F, 0, 1, -1, vexNDS3},
-	// VEX.128/256.0F.WIG — packed single-precision arithmetic.
+	// VEX.128/256.0F.WIG, packed single-precision arithmetic.
 	"VADDPS":    {1, 0x58, 0, 0, -1, vexNDS3},
 	"VMULPS":    {1, 0x59, 0, 0, -1, vexNDS3},
 	"VSUBPS":    {1, 0x5C, 0, 0, -1, vexNDS3},
@@ -107,7 +107,7 @@ var vexTable = map[string]vexSpec{
 	"VXORPD":    {1, 0x57, 0, 1, -1, vexNDS3},
 	"VUNPCKHPD": {1, 0x15, 0, 1, -1, vexNDS3},
 	"VUNPCKLPD": {1, 0x14, 0, 1, -1, vexNDS3},
-	// VEX.128.F2.0F.WIG — scalar double-precision arithmetic (the packed
+	// VEX.128.F2.0F.WIG, scalar double-precision arithmetic (the packed
 	// opcodes with an F2 pp).
 	"VADDSD": {1, 0x58, 0, 3, -1, vexNDS3},
 	"VSUBSD": {1, 0x5C, 0, 3, -1, vexNDS3},
@@ -115,7 +115,7 @@ var vexTable = map[string]vexSpec{
 	"VDIVSD": {1, 0x5E, 0, 3, -1, vexNDS3},
 	"VMINSD": {1, 0x5D, 0, 3, -1, vexNDS3},
 	"VMAXSD": {1, 0x5F, 0, 3, -1, vexNDS3},
-	// VEX.128.F3.0F.WIG — scalar single-precision arithmetic (the packed
+	// VEX.128.F3.0F.WIG, scalar single-precision arithmetic (the packed
 	// opcodes with an F3 pp).
 	"VADDSS": {1, 0x58, 0, 2, -1, vexNDS3},
 	"VSUBSS": {1, 0x5C, 0, 2, -1, vexNDS3},
@@ -123,10 +123,10 @@ var vexTable = map[string]vexSpec{
 	"VDIVSS": {1, 0x5E, 0, 2, -1, vexNDS3},
 	"VMINSS": {1, 0x5D, 0, 2, -1, vexNDS3},
 	"VMAXSS": {1, 0x5F, 0, 2, -1, vexNDS3},
-	// VEX.128/256.66.0F38.W1 — fused multiply-add (NDS form).
+	// VEX.128/256.66.0F38.W1, fused multiply-add (NDS form).
 	"VFMADD231PD": {2, 0xB8, 1, 1, -1, vexNDS3},
 
-	// VEX.128/256.66.0F38.WIG — sign/zero extend and broadcast (reg=dst, rm=src,
+	// VEX.128/256.66.0F38.WIG, sign/zero extend and broadcast (reg=dst, rm=src,
 	// no vvvv).
 	"VPMOVSXWD":    {2, 0x23, 0, 1, -1, vexRM},
 	"VPMOVSXDQ":    {2, 0x25, 0, 1, -1, vexRM},
@@ -143,70 +143,70 @@ var vexTable = map[string]vexSpec{
 	"VPBROADCASTQ": {2, 0x59, 0, 1, -1, vexRM},
 	"VPBROADCASTB": {2, 0x78, 0, 1, -1, vexRM},
 	"VPBROADCASTW": {2, 0x79, 0, 1, -1, vexRM},
-	// VEX.128/256.F3.0F.WIG — signed dword to packed double conversion
+	// VEX.128/256.F3.0F.WIG, signed dword to packed double conversion
 	// (reg=dst, rm=src, no vvvv; the length follows the destination).
 	"VCVTDQ2PD": {1, 0xE6, 0, 2, -1, vexRM},
-	// VEX.128/256.0F.WIG — signed dword to packed single conversion
+	// VEX.128/256.0F.WIG, signed dword to packed single conversion
 	// (reg=dst, rm=src, no vvvv, no mandatory prefix).
 	"VCVTDQ2PS": {1, 0x5B, 0, 0, -1, vexRM},
-	// VEX.128/256.0F.WIG — packed single to packed double conversion
+	// VEX.128/256.0F.WIG, packed single to packed double conversion
 	// (reg=dst, rm=src; the destination is the wide operand and sets the
 	// length).  Intel's maps prescribe the F3 prefix here (VEX.pp = 10), but
 	// the Go assembler emits the instruction with pp = 00, and gasm follows
-	// the Go assembler's bytes — its machine code is the oracle, not the
+	// the Go assembler's bytes, its machine code is the oracle, not the
 	// manual.
 	"VCVTPS2PD": {1, 0x5A, 0, 0, -1, vexRM},
-	// VEX.128.F2.0F.WIG — duplicate the low double of each 128-bit lane
+	// VEX.128.F2.0F.WIG, duplicate the low double of each 128-bit lane
 	// (reg=dst, rm=src, no vvvv; the length follows the destination).
 	"VMOVDDUP": {1, 0x12, 0, 3, -1, vexRM},
-	// VEX.128/256.66.0F.WIG — move mask to a GPR (reg=gpr dst, rm=vec src).
+	// VEX.128/256.66.0F.WIG, move mask to a GPR (reg=gpr dst, rm=vec src).
 	"VPMOVMSKB": {1, 0xD7, 0, 1, -1, vexRM},
 	"VMOVMSKPS": {1, 0x50, 0, 0, -1, vexRM}, // no 66 prefix (that would be VMOVMSKPD)
 
-	// VEX.128/256.66.0F.WIG — immediate shifts (opdigit selects the shift).
+	// VEX.128/256.66.0F.WIG, immediate shifts (opdigit selects the shift).
 	"VPSLLD": {1, 0x72, 0, 1, 6, vexShiftImm},
 	"VPSRAD": {1, 0x72, 0, 1, 4, vexShiftImm},
 	"VPSRLD": {1, 0x72, 0, 1, 2, vexShiftImm},
 	"VPSRLQ": {1, 0x73, 0, 1, 2, vexShiftImm},
 	"VPSLLQ": {1, 0x73, 0, 1, 6, vexShiftImm},
 
-	// VEX.128/256.66.0F.WIG — immediate shuffle (reg=dst, rm=src, imm8).
+	// VEX.128/256.66.0F.WIG, immediate shuffle (reg=dst, rm=src, imm8).
 	"VPSHUFD": {1, 0x70, 0, 1, -1, vexImmRM},
-	// VEX.256.66.0F3A.W1 — qword permute (reg=dst, rm=src, imm8).
+	// VEX.256.66.0F3A.W1, qword permute (reg=dst, rm=src, imm8).
 	"VPERMQ": {3, 0x00, 1, 1, -1, vexImmRM},
 
-	// VEX.128/256.66.0F.WIG — two-source shuffle (reg=dst, vvvv=src1, rm=src2,
+	// VEX.128/256.66.0F.WIG, two-source shuffle (reg=dst, vvvv=src1, rm=src2,
 	// imm8).
 	"VSHUFPD": {1, 0xC6, 0, 1, -1, vexNDS3Imm},
-	// VEX.256.66.0F3A.W0 — permute / insert (same shape; VINSERTI128's rm is
+	// VEX.256.66.0F3A.W0, permute / insert (same shape; VINSERTI128's rm is
 	// the XMM or memory source).
 	"VPERM2I128":  {3, 0x46, 0, 1, -1, vexNDS3Imm},
 	"VINSERTI128": {3, 0x38, 0, 1, -1, vexNDS3Imm},
 
-	// VEX.256.66.0F3A.W0 — lane extract (reg=YMM src, rm=XMM/memory dst, imm8).
+	// VEX.256.66.0F3A.W0, lane extract (reg=YMM src, rm=XMM/memory dst, imm8).
 	"VEXTRACTI128": {3, 0x39, 0, 1, -1, vexExtract},
 	"VEXTRACTF128": {3, 0x19, 0, 1, -1, vexExtract},
-	// VEX.128/256.66.0F3A.W0 — half-precision convert back ($imm, src, dst:
+	// VEX.128/256.66.0F3A.W0, half-precision convert back ($imm, src, dst:
-	// reg=src, rm=XMM/memory dst, imm8 — the extract layout).
+	// reg=src, rm=XMM/memory dst, imm8, the extract layout).
 	"VCVTPS2PH": {3, 0x1D, 0, 1, -1, vexExtract},
 
-	// VEX.128.0F.W0 — no operands.
+	// VEX.128.0F.W0, no operands.
 	"VZEROUPPER": {1, 0x77, 0, 0, -1, vexZero},
 
-	// VEX.128.0F.W0 — mask-register test (KTESTW k1, k2: reg = dst, rm = src).
+	// VEX.128.0F.W0, mask-register test (KTESTW k1, k2: reg = dst, rm = src).
 	"KTESTW": {1, 0x99, 0, 0, -1, vexRM},
 
-	// VEX.66.0F38.W0 — broadcast a single/double to all lanes (reg=dst,
+	// VEX.66.0F38.W0, broadcast a single/double to all lanes (reg=dst,
 	// rm=scalar memory; SD is 256-bit only).
 	"VBROADCASTSS": {2, 0x18, 0, 1, -1, vexRM},
 	"VBROADCASTSD": {2, 0x19, 0, 1, -1, vexRM},
-	// VEX.66.0F38.W0 — half-precision convert (reg=dst, rm=half-width
+	// VEX.66.0F38.W0, half-precision convert (reg=dst, rm=half-width
 	// source).
 	"VCVTPH2PS": {2, 0x13, 0, 1, -1, vexRM},
-	// VEX.F3.0F.WIG — replicate even/odd singles (reg=dst, rm=src).
+	// VEX.F3.0F.WIG, replicate even/odd singles (reg=dst, rm=src).
 	"VMOVSLDUP": {1, 0x12, 0, 2, -1, vexRM},
 	"VMOVSHDUP": {1, 0x16, 0, 2, -1, vexRM},
-	// VEX.66.0F.WIG — packed double to packed single conversion, the X/Y
+	// VEX.66.0F.WIG, packed double to packed single conversion, the X/Y
 	// spellings: the destination is always XMM and the spelling fixes the
 	// source length (X = 128, Y = 256).
 	"VCVTPD2PSX": {1, 0x5A, 0, 1, -1, vexRMSrcLen},
@@ -230,14 +230,14 @@ var vexTable = map[string]vexSpec{
 	"VCVTSI2SSL": {1, 0x2A, 0, 2, -1, vexNDS3},
 	"VCVTSI2SSQ": {1, 0x2A, 1, 2, -1, vexNDS3},
 
-	// VEX.128/256.66.0F.WIG — word shifts (opdigit selects the shift).
+	// VEX.128/256.66.0F.WIG, word shifts (opdigit selects the shift).
 	"VPSRLW": {1, 0x71, 0, 1, 2, vexShiftImm},
 	"VPSRAW": {1, 0x71, 0, 1, 4, vexShiftImm},
 	"VPSLLW": {1, 0x71, 0, 1, 6, vexShiftImm},
 
-	// VEX.F2.0F — packed double to packed dword conversions, truncating and
+	// VEX.F2.0F, packed double to packed dword conversions, truncating and
 	// non-truncating.  The destination is always XMM; the X/Y spellings fix
-	// the source length (XMM/YMM), and VEX.L follows it — see vexSrcLen.
+	// the source length (XMM/YMM), and VEX.L follows it, see vexSrcLen.
 	"VCVTPD2DQX":  {1, 0xE6, 0, 3, -1, vexRMSrcLen},
 	"VCVTPD2DQY":  {1, 0xE6, 0, 3, -1, vexRMSrcLen},
 	"VCVTTPD2DQX": {1, 0xE6, 0, 1, -1, vexRMSrcLen},
@@ -257,7 +257,7 @@ var vexSrcLen = map[string]int{
 	"VCVTPD2PSY":  1,
 }
 
-// vexVarShift maps the shift mnemonics to their variable-count opcode — the
+// vexVarShift maps the shift mnemonics to their variable-count opcode, the
 // form whose count comes from an XMM register or memory (VPSRLQ X0, Y8, Y8),
 // an ordinary NDS encoding rather than the /digit immediate form above.
 var vexVarShift = map[string]byte{
@@ -288,20 +288,20 @@ type vexMoveSpec struct {
 
 // vexMoveTable maps an upper-case move mnemonic to its encoding.
 var vexMoveTable = map[string]vexMoveSpec{
-	// VEX.128/256.F3.0F.WIG — unaligned integer move.
+	// VEX.128/256.F3.0F.WIG, unaligned integer move.
 	"VMOVDQU": {1, 2, 0x6F, 0x7F, 0, 0, 0, 0, true, false, false},
-	// VEX.128/256.66.0F.WIG — unaligned packed double move.
+	// VEX.128/256.66.0F.WIG, unaligned packed double move.
 	"VMOVUPD": {1, 1, 0x10, 0x11, 0, 0, 0, 0, true, false, false},
-	// VEX.128.66.0F.W0 — 32-bit GPR/memory ↔ XMM.
+	// VEX.128.66.0F.W0, 32-bit GPR/memory ↔ XMM.
 	"VMOVD": {1, 1, 0x6E, 0x7E, 0, 0, 0, 0, false, true, true},
-	// VMOVQ — 66 6E W1 (r/m→xmm), 66 7E W1 (xmm→r/m), 66 D6 W0 (xmm→xmm).
+	// VMOVQ, 66 6E W1 (r/m→xmm), 66 7E W1 (xmm→r/m), 66 D6 W0 (xmm→xmm).
 	"VMOVQ": {1, 1, 0x6E, 0x7E, 1, 1, 0xD6, 0, true, true, true},
-	// VEX.128.F2.0F.WIG — scalar double move, memory operands only (the
+	// VEX.128.F2.0F.WIG, scalar double move, memory operands only (the
 	// register form takes three operands and is not supported yet).
 	"VMOVSD": {1, 3, 0x10, 0x11, 0, 0, 0, 0, false, false, true},
-	// VEX.128.F3.0F.WIG — scalar single move, memory operands only.
+	// VEX.128.F3.0F.WIG, scalar single move, memory operands only.
 	"VMOVSS": {1, 2, 0x10, 0x11, 0, 0, 0, 0, false, false, true},
-	// VEX.128/256 — aligned packed moves.
+	// VEX.128/256, aligned packed moves.
 	"VMOVAPS": {1, 0, 0x28, 0x29, 0, 0, 0, 0, true, false, false},
 	"VMOVAPD": {1, 1, 0x28, 0x29, 0, 0, 0, 0, true, false, false},
 }
@@ -317,7 +317,7 @@ func isVex(mnemUpper string) bool {
 
 // encodeVex encodes a VEX instruction with operands in Plan 9 order.
 func (e *enc) encodeVex(mnemUpper string, ops []Operand) error {
-	// Vector register indices 16–31 exist only in EVEX encodings; fail
+	// Vector register indices 16-31 exist only in EVEX encodings; fail
 	// loudly rather than silently truncating the index.
 	for _, op := range ops {
 		if r, ok := op.(Reg); ok && r.isVec() && r.idx >= 16 {
@@ -420,7 +420,7 @@ func (e *enc) encodeVexRM(spec vexSpec, ops []Operand) error {
 }
 
 // encodeVexRMSrcLen encodes a length-narrowing conversion: OP src, dst with
-// the destination always XMM and the VEX.L bit following the source — fixed
+// the destination always XMM and the VEX.L bit following the source, fixed
 // by the mnemonic's spelling (VCVTPD2DQX = 128, VCVTPD2DQY = 256) even when
 // the source is memory.
 func (e *enc) encodeVexRMSrcLen(mnem string, spec vexSpec, ops []Operand) error {

asm/vex_test.go

@@ -173,7 +173,7 @@ func TestVexGroundTruth(t *testing.T) {
 		{"VPMULLD Y1,Y2,Y3", "VPMULLD", []Operand{vreg(t, "Y1"), vreg(t, "Y2"), vreg(t, "Y3")}, "c4e26d40d9", ""},
 		{"VPUNPCKLDQ Y4,Y3,Y5", "VPUNPCKLDQ", []Operand{vreg(t, "Y4"), vreg(t, "Y3"), vreg(t, "Y5")}, "c5e562ec", ""},
 		{"VPERMD Y1,Y2,Y3", "VPERMD", []Operand{vreg(t, "Y1"), vreg(t, "Y2"), vreg(t, "Y3")}, "c4e26d36d9", ""},
-		// Floating point (packed and scalar) and FMA — same NDS form, the pp
+		// Floating point (packed and scalar) and FMA; same NDS form, the pp
 		// bits and map select the operation.
 		{"VADDPD Y9,Y8,Y8", "VADDPD", []Operand{vreg(t, "Y9"), vreg(t, "Y8"), vreg(t, "Y8")}, "c4413d58c1", ""},
 		{"VADDPD X1,X2,X3", "VADDPD", []Operand{vreg(t, "X1"), vreg(t, "X2"), vreg(t, "X3")}, "c5e958d9", ""},
@@ -217,7 +217,7 @@ func TestVexGroundTruth(t *testing.T) {
 		{"VEXTRACTI128 $1,Y8,X9", "VEXTRACTI128", []Operand{Imm(1), vreg(t, "Y8"), vreg(t, "X9")}, "c4437d39c101", ""},
 		{"VEXTRACTI128 $1,Y8,(DI)", "VEXTRACTI128", []Operand{Imm(1), vreg(t, "Y8"), Ptr(DI, 0, 16)}, "c4637d390701", ""},
 		{"VEXTRACTF128 $1,Y8,X9", "VEXTRACTF128", []Operand{Imm(1), vreg(t, "Y8"), vreg(t, "X9")}, "c4437d19c101", ""},
-		// Moves — each direction picks its own opcode and VEX.W.
+		// Moves; each direction picks its own opcode and VEX.W.
 		{"VMOVDQU (SI),Y1", "VMOVDQU", []Operand{Ptr(SI, 0, 32), vreg(t, "Y1")}, "c5fe6f0e", ""},
 		{"VMOVDQU Y3,(DI)", "VMOVDQU", []Operand{vreg(t, "Y3"), Ptr(DI, 0, 32)}, "c5fe7f1f", ""},
 		{"VMOVDQU X1,X2", "VMOVDQU", []Operand{vreg(t, "X1"), vreg(t, "X2")}, "c5fa7fca", ""},
@@ -234,7 +234,7 @@ func TestVexGroundTruth(t *testing.T) {
 		{"VMOVD AX,X0", "VMOVD", []Operand{AX, vreg(t, "X0")}, "c5f96ec0", ""},
 		{"VMOVSD (SI),X8", "VMOVSD", []Operand{Ptr(SI, 0, 8), vreg(t, "X8")}, "c57b1006", ""},
 		{"VMOVSD X8,(SI)", "VMOVSD", []Operand{vreg(t, "X8"), Ptr(SI, 0, 8)}, "c57b1106", ""},
-		// Packed double arithmetic and unpack — the NDS form, the opcode
+		// Packed double arithmetic and unpack; the NDS form, the opcode
 		// selects the operation.
 		{"VSUBPD Y1,Y2,Y3", "VSUBPD", []Operand{vreg(t, "Y1"), vreg(t, "Y2"), vreg(t, "Y3")}, "c5ed5cd9", ""},
 		{"VDIVPD X1,X2,X3", "VDIVPD", []Operand{vreg(t, "X1"), vreg(t, "X2"), vreg(t, "X3")}, "c5e95ed9", ""},
@@ -255,12 +255,12 @@ func TestVexGroundTruth(t *testing.T) {
 		{"VMINSS X6,X7,X8", "VMINSS", []Operand{vreg(t, "X6"), vreg(t, "X7"), vreg(t, "X8")}, "c5425dc6", ""},
 		{"VMAXSS X1,X2,X3", "VMAXSS", []Operand{vreg(t, "X1"), vreg(t, "X2"), vreg(t, "X3")}, "c5ea5fd9", ""},
 		{"VADDSD 8(AX),X1,X2", "VADDSD", []Operand{Ptr(AX, 8, 8), vreg(t, "X1"), vreg(t, "X2")}, "c5f3585008", ""},
-		// VMOVDDUP — duplicate the low double (reg=dst, rm=src, F2 pp).
+		// VMOVDDUP; duplicate the low double (reg=dst, rm=src, F2 pp).
 		{"VMOVDDUP X1,X2", "VMOVDDUP", []Operand{vreg(t, "X1"), vreg(t, "X2")}, "c5fb12d1", ""},
 		{"VMOVDDUP Y1,Y2", "VMOVDDUP", []Operand{vreg(t, "Y1"), vreg(t, "Y2")}, "c5ff12d1", ""},
 		{"VMOVDDUP 8(AX),X1", "VMOVDDUP", []Operand{Ptr(AX, 8, 8), vreg(t, "X1")}, "c5fb124808", ""},
 		// Conversions: DQ→PS (no prefix), PS→PD (Go emits it without the F3
-		// prefix — see the table comment), DQ→PD.
+		// prefix; see the table comment), DQ→PD.
 		{"VCVTDQ2PS X1,X2", "VCVTDQ2PS", []Operand{vreg(t, "X1"), vreg(t, "X2")}, "c5f85bd1", ""},
 		{"VCVTDQ2PS Y3,Y4", "VCVTDQ2PS", []Operand{vreg(t, "Y3"), vreg(t, "Y4")}, "c5fc5be3", ""},
 		{"VCVTPS2PD X1,X2", "VCVTPS2PD", []Operand{vreg(t, "X1"), vreg(t, "X2")}, "c5f85ad1", ""},

ast/ast.go

@@ -17,7 +17,7 @@ type File struct {
 	Orphans []Stmt // labels/instructions seen before any TEXT directive
 	// Macros holds the names introduced by #define directives in this file.
 	// The linter uses it to avoid flagging macro invocations as unknown
-	// instructions (macro expansion itself is out of scope — see the docs).
+	// instructions (macro expansion itself is out of scope, see the docs).
 	Macros map[string]bool
 }
 

cmd/gasm/audit.go

@@ -37,17 +37,29 @@ import (
 // construction and are excluded from the diff; the other architectures list
 // their conditional branches outright.
 func cmdAuditInstructions(args []string) error {
-	fs := newCommand("audit-instructions", "gasm audit-instructions [amd64|arm64|riscv64|loong64]", `
+	fs := newCommand("audit-instructions", "gasm audit-instructions [--corpus [dir]] [amd64|arm64|riscv64|loong64]", `
 Compare the gasm encoder for the given architecture (default amd64) against
 go tool asm and print the diff: superset encodings (gasm-only, shippable via
 gasm asm --format goobj), known-but-unencodable names (the backlog) and go-
 only names (feature gaps).  The Go side is probed black-box with a battery
 of bare mnemonics, so the audit tracks whatever toolchain `+"`go env GOROOT`"+`
 provides.
+
+With --corpus the audit changes shape: it assembles every .s file under the
+given directory (default GOROOT/src) with the gasm encoder only, no
+toolchain probing.  A file whose name carries a recognisable _arch suffix is
+attempted for that architecture; a file without one is attempted for all
+four, exactly as a GOARCH build would compile it.  The report gives the
+per-architecture pass rates and the most common failure reasons, which drive
+the encodability backlog by frequency rather than by table order.
 `)
+	corpus := fs.Bool("corpus", false, "assemble a corpus of .s files and report pass rates and failure reasons")
 	if err := fs.Parse(args); err != nil {
 		return err
 	}
+	if *corpus {
+		return cmdAuditCorpus(fs.Args())
+	}
 	archName := "amd64"
 	switch n := len(fs.Args()); {
 	case n > 1:
@@ -305,3 +317,196 @@ func gasmAssembles(a arch.Arch, name, shape string) bool {
 func sanitize(name string) string {
 	return strings.NewReplacer(".", "_", "$", "_").Replace(name)
 }
+
+// --- corpus audit -----------------------------------------------------------
+
+// corpusTarget is one architecture row of the corpus report.
+type corpusTarget struct {
+	a    arch.Arch
+	name string
+}
+
+// corpusTally accumulates one architecture's attempts over the corpus.
+type corpusTally struct {
+	attempted int
+	assembled int
+	reasons   map[string]int    // failure reason → count
+	example   map[string]string // failure reason → one representative file
+}
+
+func (t *corpusTally) fail(path, reason string) {
+	t.reasons[reason]++
+	if t.example[reason] == "" {
+		t.example[reason] = path
+	}
+}
+
+// cmdAuditCorpus implements audit-instructions --corpus.
+func cmdAuditCorpus(args []string) error {
+	if len(args) > 1 {
+		return fmt.Errorf("audit-instructions --corpus takes at most one directory argument")
+	}
+	root := ""
+	if len(args) == 1 {
+		root = args[0]
+	} else {
+		out, err := exec.Command("go", "env", "GOROOT").Output()
+		if err != nil {
+			return fmt.Errorf("locate GOROOT: %w", err)
+		}
+		root = filepath.Join(strings.TrimSpace(string(out)), "src")
+	}
+	stats, err := runCorpusAudit(root)
+	if err != nil {
+		return err
+	}
+	printCorpusStats(stats)
+	return nil
+}
+
+// corpusStats is the outcome of one corpus audit run.
+type corpusStats struct {
+	root    string
+	files   int
+	generic int // files attempted for all four architectures
+	full    int // files that assembled for every target architecture
+	targets []corpusTarget
+	tallies []*corpusTally
+}
+
+// runCorpusAudit assembles every .s file under root and returns the stats.
+func runCorpusAudit(root string) (*corpusStats, error) {
+	files, err := asmFiles(root)
+	if err != nil {
+		return nil, err
+	}
+
+	targets := []corpusTarget{
+		{arch.AMD64, "amd64"},
+		{arch.ARM64, "arm64"},
+		{arch.RISCV, "riscv64"},
+		{arch.LOONG64, "loong64"},
+	}
+	tallies := make([]*corpusTally, len(targets))
+	for i := range tallies {
+		tallies[i] = &corpusTally{reasons: map[string]int{}, example: map[string]string{}}
+	}
+	// full is the north-star number: a file counts when every architecture
+	// its name allows assembles it.
+	full, generic := 0, 0
+
+	for _, path := range files {
+		src, err := readSource(path)
+		if err != nil {
+			return nil, err
+		}
+		f, errs := parser.Parse(path, src)
+
+		var wanted []int // indexes into targets
+		if a := arch.FromFilename(path); a != arch.Unknown {
+			for i, tg := range targets {
+				if tg.a == a {
+					wanted = append(wanted, i)
+				}
+			}
+		} else {
+			generic++
+			for i := range targets {
+				wanted = append(wanted, i)
+			}
+		}
+
+		ok := true
+		for _, i := range wanted {
+			tg, t := targets[i], tallies[i]
+			t.attempted++
+			var err error
+			if len(errs) > 0 {
+				err = errs[0] // a parse failure is a failure for every target
+			} else {
+				_, err = assembleFile(tg.a, f)
+			}
+			if err != nil {
+				ok = false
+				t.fail(path, corpusReason(err))
+				continue
+			}
+			t.assembled++
+		}
+		if ok && len(wanted) > 0 {
+			full++
+		}
+	}
+
+	return &corpusStats{
+		root:    root,
+		files:   len(files),
+		generic: generic,
+		full:    full,
+		targets: targets,
+		tallies: tallies,
+	}, nil
+}
+
+// printCorpusStats renders the corpus audit report.
+func printCorpusStats(s *corpusStats) {
+	fmt.Printf("corpus %s: %d files (%d generic, attempted for all architectures)\n", s.root, s.files, s.generic)
+	fmt.Printf("  assemble for every target architecture: %d (%.1f%%)\n", s.full, 100*float64(s.full)/float64(max(s.files, 1)))
+	for i, tg := range s.targets {
+		t := s.tallies[i]
+		fmt.Printf("  %s: %d/%d attempted\n", tg.name, t.assembled, t.attempted)
+		for _, r := range topReasons(t) {
+			fmt.Printf("    %4d  %s\n", t.reasons[r], r)
+			fmt.Printf("         e.g. %s\n", t.example[r])
+		}
+	}
+}
+
+// corpusReason buckets an assembly or parse failure for the histogram.
+func corpusReason(err error) string {
+	msg := err.Error()
+	switch {
+	case strings.Contains(msg, "unsupported"), strings.Contains(msg, "cannot encode"):
+		return "instruction not encodable"
+	case strings.Contains(msg, "undefined label"):
+		return "undefined label"
+	case strings.Contains(msg, "undefined symbol"), strings.Contains(msg, "external symbol"), strings.Contains(msg, "file-level assembly"):
+		return "undefined symbol or external"
+	case strings.Contains(msg, "operand"), strings.Contains(msg, "operand form"):
+		return "unsupported operand form"
+	default:
+		return "other: " + firstLine(msg)
+	}
+}
+
+// topReasons returns at most five reasons, most frequent first.
+func topReasons(t *corpusTally) []string {
+	type kv struct {
+		k string
+		n int
+	}
+	var kvs []kv
+	for k, n := range t.reasons {
+		kvs = append(kvs, kv{k, n})
+	}
+	slices.SortFunc(kvs, func(a, b kv) int { return b.n - a.n })
+	if len(kvs) > 5 {
+		kvs = kvs[:5]
+	}
+	out := make([]string, len(kvs))
+	for i, kv := range kvs {
+		out[i] = kv.k
+	}
+	return out
+}
+
+// firstLine returns the first line of an error message, truncated.
+func firstLine(msg string) string {
+	if i := strings.IndexByte(msg, '\n'); i >= 0 {
+		msg = msg[:i]
+	}
+	if len(msg) > 80 {
+		msg = msg[:80]
+	}
+	return msg
+}

cmd/gasm/debug_linux.go

@@ -84,7 +84,7 @@ REPL commands:
 	if *timeout > 0 {
 		go func() {
 			time.Sleep(*timeout)
-			fmt.Fprintf(os.Stderr, "gasm debug: timeout (%s) — killing the debuggee\n", *timeout)
+			fmt.Fprintf(os.Stderr, "gasm debug: timeout (%s), killing the debuggee\n", *timeout)
 			os.Exit(3)
 		}()
 	}
@@ -140,7 +140,6 @@ REPL commands:
 		}
 
 		// Construct the argument block with buffer pointers at the correct positions.
-		bufIdx := 0
 		for _, arg := range layout {
 			if !arg.IsPtr {
 				continue
@@ -170,12 +169,10 @@ REPL commands:
 							argBlock[off+16+j] = byte(size >> (j * 8))
 						}
 					}
-					bufIdx++
 					break
 				}
 			}
 		}
-		_ = bufIdx
 	} else {
 		argBlock = make([]byte, fl.Args)
 		sess, err = debug.Launch("", path, *funcName, argBlock)

cmd/gasm/dis.go

@@ -0,0 +1,148 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"sort"
+	"strings"
+
+	"sourcedock.dev/petrbalvin/gasm-devkit/arch"
+	"sourcedock.dev/petrbalvin/gasm-devkit/disasm"
+	"sourcedock.dev/petrbalvin/gasm-devkit/parser"
+)
+
+// cmdDis disassembles machine code: either a raw binary (standard input with
+// "-") whose architecture is given with -a, or a .s file, which is assembled
+// first so the listing shows the real function and label layout.
+func cmdDis(args []string) int {
+	fs := newCommand("dis", "gasm dis [-a arch] <file>", `
+Disassemble machine code to instruction text (via golang.org/x/arch).
+
+With a .s file, the file is assembled first and the listing follows the
+real layout: one block per TEXT function, local labels printed at their
+offsets.  The architecture comes from the file name suffix, or from -a.
+
+With any other file, or "-" for standard input, the bytes are disassembled
+linearly and -a selects the architecture (amd64, arm64, riscv64 or
+loong64).
+`)
+	archName := fs.String("a", "", "architecture for raw input: amd64, arm64, riscv64 or loong64")
+	fs.Parse(args)
+	if fs.NArg() != 1 {
+		fmt.Fprintln(os.Stderr, "usage: gasm dis [-a arch] <file>")
+		return 2
+	}
+	path := fs.Arg(0)
+	var target arch.Arch
+	if *archName != "" {
+		var err error
+		target, err = auditArch(*archName)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "gasm dis: %v\n", err)
+			return 2
+		}
+	}
+
+	if strings.HasSuffix(path, ".s") {
+		if target == arch.Unknown {
+			target = arch.FromFilename(path)
+		}
+		if target == arch.Unknown {
+			fmt.Fprintln(os.Stderr, "gasm dis: cannot infer the architecture from the file name; use -a")
+			return 2
+		}
+		return disSource(path, target)
+	}
+
+	if target == arch.Unknown {
+		fmt.Fprintln(os.Stderr, "gasm dis: raw input needs -a (amd64, arm64, riscv64 or loong64)")
+		return 2
+	}
+	src, err := readSource(path)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "gasm dis:", err)
+		return 1
+	}
+	printListing(target, []byte(src), 0, nil)
+	return 0
+}
+
+// disSource assembles a .s file and prints one listing block per function.
+func disSource(path string, target arch.Arch) int {
+	src, err := readSource(path)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "gasm dis:", err)
+		return 1
+	}
+	f, errs := parser.Parse(path, src)
+	for _, e := range errs {
+		fmt.Fprintf(os.Stderr, "%s: %v\n", path, e)
+	}
+	if len(errs) > 0 {
+		return 1
+	}
+	img, err := assembleFile(target, f)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "gasm dis: %v\n", err)
+		return 1
+	}
+	if len(img.Funcs) == 0 {
+		fmt.Fprintln(os.Stderr, "gasm dis: no assemblable TEXT functions found")
+		return 1
+	}
+	for _, fn := range img.Funcs {
+		code := img.Code[fn.Offset : fn.Offset+fn.Size]
+		fmt.Printf("%s: %d bytes\n", fn.Name, fn.Size)
+		labels := make(map[int][]string, len(fn.Labels))
+		for name, off := range fn.Labels {
+			labels[off] = append(labels[off], name)
+		}
+		for off := range labels {
+			sort.Strings(labels[off])
+		}
+		printListing(target, code, uint64(fn.Offset), labels)
+	}
+	if len(img.Data) > 0 {
+		fmt.Printf("data: %d bytes at 0x%x\n", len(img.Data), len(img.Code))
+	}
+	return 0
+}
+
+// printListing decodes code linearly from offset base, printing label lines
+// (label name to offset within the block) as they are reached.
+func printListing(a arch.Arch, code []byte, base uint64, labels map[int][]string) {
+	pc := 0
+	for pc < len(code) {
+		for _, name := range labels[pc] {
+			fmt.Printf("%s:\n", name)
+		}
+		ins, err := disasm.Decode(a, code[pc:], base+uint64(pc))
+		if err != nil {
+			break
+		}
+		end := min(pc+ins.Len, len(code))
+		fmt.Printf("  %04x: %-16s %s\n", base+uint64(pc), hexBytes(code[pc:end]), ins.Text)
+		if ins.Len <= 0 {
+			break
+		}
+		pc += ins.Len
+	}
+}
+
+// hexBytes renders up to 8 bytes as contiguous hex.
+func hexBytes(b []byte) string {
+	var sb strings.Builder
+	for i, c := range b {
+		if i == 8 {
+			break
+		}
+		if i > 0 {
+			sb.WriteByte(' ')
+		}
+		fmt.Fprintf(&sb, "%02x", c)
+	}
+	return sb.String()
+}

cmd/gasm/main.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
 // SPDX-License-Identifier: BSD-3-Clause
 
-// Command gasm is the developer frontend for GAsm — Go's Plan 9 assembler.
+// Command gasm is the developer frontend for GAsm, Go's Plan 9 assembler.
 // It bundles a token dumper, a parser, a formatter, a linter and a language
 // server into one binary.  Every subcommand works headlessly so it can be
 // driven from scripts and CI as well as from an editor.
@@ -18,6 +18,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"runtime"
+	"runtime/debug"
 	"slices"
 	"sort"
 	"strconv"
@@ -36,9 +37,16 @@ import (
 	"sourcedock.dev/petrbalvin/gasm-devkit/verify"
 )
 
-// version is the release version, stamped at build time via
+// version reports the release the toolchain recorded for this build: the
-// -ldflags "-X main.version=…" (defaulting to the current release).
+// tag on a tag, a pseudo-version below one, and (devel) outside version
-var version = "0.32.0"
+// control. Nothing is injected; the recorded value cannot go stale.
+func version() string {
+	bi, ok := debug.ReadBuildInfo()
+	if !ok || bi.Main.Version == "" {
+		return "(devel)"
+	}
+	return bi.Main.Version
+}
 
 func main() {
 	if len(os.Args) < 2 {
@@ -56,6 +64,8 @@ func main() {
 		os.Exit(cmdLint(os.Args[2:]))
 	case "asm":
 		os.Exit(cmdAsm(os.Args[2:]))
+	case "dis":
+		os.Exit(cmdDis(os.Args[2:]))
 	case "verify":
 		os.Exit(cmdVerify(os.Args[2:]))
 	case "debug":
@@ -81,18 +91,18 @@ func main() {
 	case "help", "--help", "-h":
 		usage(os.Stdout)
 	default:
-		fmt.Fprintf(os.Stderr, "gasm: unknown command %q — run \"gasm --help\" for usage\n", os.Args[1])
+		fmt.Fprintf(os.Stderr, "gasm: unknown command %q; run \"gasm --help\" for usage\n", os.Args[1])
 		os.Exit(2)
 	}
 }
 
-// cmdVersion prints the release version.
+// cmdVersion prints the recorded version.
 func cmdVersion() int {
-	fmt.Printf("gasm %s\n", version)
+	fmt.Printf("gasm %s\n", version())
 	return 0
 }
 
-// ANSI color helpers for terminal output.
+// ANSI colour helpers for terminal output.
 const (
 	colorReset  = "\033[0m"
 	colorBold   = "\033[1m"
@@ -101,7 +111,7 @@ const (
 	colorGray   = "\033[90m"
 )
 
-// isTTY reports whether the writer is a terminal (for color output).
+// isTTY reports whether the writer is a terminal (for colour output).
 func isTTY(w io.Writer) bool {
 	if f, ok := w.(*os.File); ok {
 		stat, _ := f.Stat()
@@ -117,7 +127,7 @@ func usage(w io.Writer) {
 		bold, cyan, yellow, gray, reset = colorBold, colorCyan, colorYellow, colorGray, colorReset
 	}
 
-	fmt.Fprintf(w, "%sgasm %s%s — developer tooling for Go's Plan 9 assembler (GAsm)%s\n\n", bold, version, reset, reset)
+	fmt.Fprintf(w, "%sgasm %s%s: developer tooling for Go's Plan 9 assembler (GAsm)%s\n\n", bold, version(), reset, reset)
 	fmt.Fprintf(w, "gasm bundles a lexer, parser, formatter, linter, standalone assembler and\n")
 	fmt.Fprintf(w, "language server for Plan 9 assembly into one self-contained binary.\n\n")
 
@@ -132,6 +142,7 @@ func usage(w io.Writer) {
 		{"fmt", "canonicalise formatting (gofmt for assembly)"},
 		{"lint", "run static checks"},
 		{"asm", "assemble .s files to machine code (amd64, arm64, riscv64, loong64)"},
+		{"dis", "disassemble machine code (raw bytes or an assembled .s file)"},
 		{"verify", "JIT-assemble and run dynamic checks (amd64, arm64, riscv64, loong64)"},
 		{"debug", "interactive source-level debugger (amd64, arm64, riscv64, loong64)"},
 		{"diff", "compare machine code of two .s files"},
@@ -263,24 +274,34 @@ standard input.
 			funcs++
 		}
 	}
-	fmt.Printf("%s: OK — %d declarations, %d functions\n", path, len(file.Decls), funcs)
+	fmt.Printf("%s: OK, %d declarations, %d functions\n", path, len(file.Decls), funcs)
 	return 0
 }
 
 func cmdFmt(args []string) int {
-	fs := newCommand("fmt", "gasm fmt [-w] [path...]", `
+	fs := newCommand("fmt", "gasm fmt [-w|-l|-d] [path...]", `
 Canonicalise the formatting of Plan 9 assembly sources: indentation, operand
 spacing, per-function mnemonic alignment and blank-line layout (exactly one
 blank line before each label, TEXT and GLOBL block).  Formatting is
 idempotent and preserves every line, comments included.
 
-With no paths — or a directory path — every .s file below it is reformatted
+With no paths, or a directory path, every .s file below it is reformatted
 in place and the changed files are listed, the way go fmt does; "." and "_"
 directories are skipped.  Explicit file paths print to stdout unless -w is
 given.
+
+-l and -d rewrite nothing: -l prints the paths whose formatting differs
+from gasm's (empty output means everything is formatted, which is what a CI
+check wants), -d prints the diffs.  They are mutually exclusive.
 `)
 	write := fs.Bool("w", false, "write result to the source file")
+	list := fs.Bool("l", false, "list files whose formatting differs from gasm's")
+	diffMode := fs.Bool("d", false, "print diffs instead of rewriting files")
 	fs.Parse(args)
+	if *list && *diffMode {
+		fmt.Fprintln(os.Stderr, "gasm fmt: -l and -d are mutually exclusive")
+		return 2
+	}
 	// Like go fmt: with no arguments, or with a directory argument, every .s
 	// file below the directory is formatted in place and the names of the
 	// changed files are listed; explicit file arguments keep the -w / stdout
@@ -318,6 +339,16 @@ given.
 			continue
 		}
 		out := format.Source(src)
+		if *list || *diffMode {
+			if out != src {
+				if *list {
+					fmt.Println(path)
+				} else {
+					fmt.Print(unifiedDiff(path, strings.Split(src, "\n"), strings.Split(out, "\n")))
+				}
+			}
+			continue
+		}
 		if dirMode || *write {
 			if out != src {
 				if err := os.WriteFile(path, []byte(out), 0o644); err != nil {
@@ -337,7 +368,7 @@ given.
 }
 
 // asmFiles collects the .s files below dir, skipping directories whose name
-// starts with "." or "_" — as the go tooling does, which keeps .git and
+// starts with "." or "_", as the go tooling does, which keeps .git and
 // scratch or reference trees (e.g. _refs) untouched.
 func asmFiles(dir string) ([]string, error) {
 	var out []string
@@ -419,6 +450,7 @@ hover, document symbols, diagnostics and semantic-token highlighting.
 `)
 	fs.Parse(args)
 	srv := lsp.New(os.Stdin, os.Stdout)
+	srv.SetVersion(version())
 	if err := srv.Run(); err != nil {
 		fmt.Fprintln(os.Stderr, "gasm lsp:", err)
 		return 1
@@ -427,7 +459,7 @@ hover, document symbols, diagnostics and semantic-token highlighting.
 }
 
 func cmdAsm(args []string) int {
-	fs := newCommand("asm", "gasm asm [--format raw|elf|goobj] [-p pkg] [-o out] <file>", `
+	fs := newCommand("asm", "gasm asm [--format raw|elf|goobj] [-p pkg] [-GOARCH arch] [-o out] <file>", `
 	Assemble FILE without the Go toolchain: every TEXT function is encoded to
 	machine code and printed as a hex dump.  Supported architectures: amd64
 	(including VEX/AVX2 and EVEX/AVX-512), arm64 (AArch64 integer, FP,
@@ -445,13 +477,22 @@ requires -p, the package path, and the installed Go toolchain).
 	out := fs.String("o", "", "write the output to this file")
 	format := fs.String("format", "raw", "output format: raw (concatenated image), elf or goobj (Go object)")
 	pkg := fs.String("p", "", "package path for --format goobj (qualifies the exported symbols)")
+	archName := fs.String("GOARCH", "", "target architecture: amd64, arm64, riscv64 or loong64 (overrides the file-name suffix)")
 	fs.Parse(args)
 	if fs.NArg() != 1 {
-		fmt.Fprintln(os.Stderr, "usage: gasm asm [--format raw|elf|goobj] [-p pkg] [-o out] <file>")
+		fmt.Fprintln(os.Stderr, "usage: gasm asm [--format raw|elf|goobj] [-p pkg] [-GOARCH arch] [-o out] <file>")
 		return 2
 	}
 	path := fs.Arg(0)
 	targetArch := arch.FromFilename(path)
+	if *archName != "" {
+		a, err := auditArch(*archName)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "gasm asm: %v\n", err)
+			return 2
+		}
+		targetArch = a
+	}
 	src, err := readSource(path)
 	if err != nil {
 		fmt.Fprintln(os.Stderr, "gasm:", err)
@@ -470,8 +511,10 @@ requires -p, the package path, and the installed Go toolchain).
 		fmt.Fprintf(os.Stderr, "%s: %v\n", path, err)
 		return 1
 	}
-	if len(img.Funcs) == 0 {
+	if len(img.Funcs) == 0 && len(img.Data) == 0 {
-		fmt.Fprintln(os.Stderr, "gasm asm: no assemblable TEXT functions found")
+		// A file with neither code nor data assembles to nothing, which is
+		// almost always a wrong architecture rather than an intent.
+		fmt.Fprintln(os.Stderr, "gasm asm: no assemblable TEXT functions or GLOBL data found")
 		return 1
 	}
 	for _, fn := range img.Funcs {
@@ -562,7 +605,7 @@ requires -p, the package path, and the installed Go toolchain).
 
 // cmdDiff compares the machine code of two assembly files.
 func cmdDiff(args []string) int {
-	set := newCommand("diff", "gasm diff <file1.s> <file2.s>", `
+	set := newCommand("diff", "gasm diff [-GOARCH arch] <file1.s> <file2.s>", `
 Compare the machine code produced by assembling two files.
 Shows which functions differ and the byte-level differences.
 Useful for verifying that two implementations produce identical code,
@@ -572,12 +615,22 @@ Use --map to compare functions whose names differ between the files,
 e.g. --map wideCopyAVX2=wideCopyAVX512 pairs the two regardless of suffix.
 `)
 	mapSpec := set.String("map", "", "comma-separated old=new pairs to match functions with different names")
+	archName := set.String("GOARCH", "", "target architecture for both files: amd64, arm64, riscv64 or loong64")
 	set.Parse(args)
 	if set.NArg() != 2 {
-		fmt.Fprintln(os.Stderr, "usage: gasm diff <file1.s> <file2.s>")
+		fmt.Fprintln(os.Stderr, "usage: gasm diff [-GOARCH arch] <file1.s> <file2.s>")
 		return 2
 	}
 	path1, path2 := set.Arg(0), set.Arg(1)
+	forced := arch.Unknown
+	if *archName != "" {
+		a, err := auditArch(*archName)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "gasm diff: %v\n", err)
+			return 2
+		}
+		forced = a
+	}
 
 	// Parse the name mapping (file1 name → file2 name).
 	nameMap := make(map[string]string)
@@ -593,12 +646,12 @@ e.g. --map wideCopyAVX2=wideCopyAVX512 pairs the two regardless of suffix.
 	}
 
 	// Assemble both files.
-	img1, err := assemblePath(path1)
+	img1, err := assemblePath(path1, forced)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "gasm diff: %s: %v\n", path1, err)
 		return 1
 	}
-	img2, err := assemblePath(path2)
+	img2, err := assemblePath(path2, forced)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "gasm diff: %s: %v\n", path2, err)
 		return 1
@@ -673,8 +726,9 @@ func assembleFile(targetArch arch.Arch, f *ast.File) (*asm.Image, error) {
 	}
 }
 
-// assemblePath reads, parses and assembles a file (used by cmdDiff).
+// assemblePath reads, parses and assembles a file (used by cmdDiff).  A
-func assemblePath(path string) (*asm.Image, error) {
+// non-Unknown forced architecture overrides the file-name suffix.
+func assemblePath(path string, forced arch.Arch) (*asm.Image, error) {
 	src, err := readSource(path)
 	if err != nil {
 		return nil, err
@@ -686,7 +740,11 @@ func assemblePath(path string) (*asm.Image, error) {
 	if len(errs) > 0 {
 		return nil, fmt.Errorf("parse errors")
 	}
-	return assembleFile(arch.FromFilename(path), f)
+	target := forced
+	if target == arch.Unknown {
+		target = arch.FromFilename(path)
+	}
+	return assembleFile(target, f)
 }
 
 // printByteDiff shows the first few byte differences between two code blocks.
@@ -765,9 +823,11 @@ gasm verify --fuzz which exercises the code paths.
 	return 0
 }
 
-// cmdVerifyRISCV handles the verify subcommand for RISC-V files.
+// cmdVerifyNonJIT handles the verify subcommand for files whose architecture
-// JIT requires RISC-V hardware; only ground-truth and profile are available.
+// the host cannot execute: only the ground-truth comparison and the static
-func cmdVerifyRISCV(path string, groundTruth, profile bool) int {
+// profile are available there.  Relocation sites are masked before the byte
+// comparison, as the toolchain leaves them zero for the linker.
+func cmdVerifyNonJIT(path string, targetArch arch.Arch, groundTruth, profile bool) int {
 	src, err := readSource(path)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "gasm verify: %v\n", err)
@@ -780,19 +840,58 @@ func cmdVerifyRISCV(path string, groundTruth, profile bool) int {
 	if len(errs) > 0 {
 		return 1
 	}
-	img, err := asm.AssembleFileRISCV(f)
+	img, err := assembleFile(targetArch, f)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "gasm verify: %v\n", err)
 		return 1
 	}
 
 	if groundTruth {
-		gt, err := verify.GroundTruthRISCV(path)
+		var gt map[string][]byte
+		switch targetArch {
+		case arch.RISCV:
+			gt, err = verify.GroundTruthRISCV(path)
+		case arch.LOONG64:
+			gt, err = verify.GroundTruthLOONG64(path)
+		case arch.ARM64:
+			gt, err = verify.GroundTruthARM64(path)
+		default:
+			gt, err = verify.GroundTruth(path)
+		}
 		if err != nil {
 			fmt.Fprintf(os.Stderr, "gasm verify: ground truth: %v\n", err)
 			return 1
 		}
-		matched, total := 0, 0
+		matched, total, diffs := compareGroundTruth(img, gt)
+		if diffs > 0 {
+			printCodeDiff(img, gt)
+		}
+		fmt.Printf("%s: %d/%d matched\n", path, matched, total)
+		if matched < total || diffs > 0 {
+			return 1
+		}
+		return 0
+	}
+
+	if profile {
+		for _, fn := range img.Funcs {
+			fmt.Printf("%s: %d bytes, labels: %v\n", fn.Name, fn.Size, fn.Labels)
+		}
+		return 0
+	}
+
+	fmt.Printf("%s: %d functions assembled\n", path, len(img.Funcs))
+	for _, fn := range img.Funcs {
+		fmt.Printf("  %s: %d bytes\n", fn.Name, fn.Size)
+	}
+	return 0
+}
+
+// compareGroundTruth compares the image's functions against the go tool asm
+// output byte-for-byte, masking relocation sites (disp32 fields the Go linker
+// fills at link time).  It prints one line per function and returns the
+// matched and compared counts plus the number of functions with byte diffs.
+func compareGroundTruth(img *asm.Image, gt map[string][]byte) (matched, total, diffs int) {
 	for _, fn := range img.Funcs {
 		gasmCode := img.Code[fn.Offset : fn.Offset+fn.Size]
 		goCode, ok := gt[fn.Name]
@@ -821,100 +920,22 @@ func cmdVerifyRISCV(path string, groundTruth, profile bool) int {
 				fmt.Printf("  %s: MATCH (%d bytes)\n", fn.Name, fn.Size)
 			}
 		} else {
+			diffs++
 			fmt.Printf("  %s: MISMATCH (%d vs %d bytes)\n", fn.Name, fn.Size, len(goCode))
-				for i := 0; i < len(gasmCode) || i < len(goCode); i += 16 {
-					var gb, gs string
-					for j := i; j < i+16 && j < len(gasmCode); j++ {
-						gb += fmt.Sprintf(" %02x", gasmCode[j])
-					}
-					for j := i; j < i+16 && j < len(goCode); j++ {
-						gs += fmt.Sprintf(" %02x", goCode[j])
-					}
-					fmt.Printf("    %04x: gasm:%s\n", i, gb)
-					fmt.Printf("    %04x: gt:  %s\n", i, gs)
 		}
 	}
-		}
+	return matched, total, diffs
-		fmt.Printf("%s: %d/%d matched\n", path, matched, total)
-		if matched < total {
-			return 1
-		}
-		return 0
 }
 
-	if profile {
+// printCodeDiff shows a 16-byte hex dump per function whose gasm bytes differ
-		for _, fn := range img.Funcs {
+// from the go tool asm output.
-			fmt.Printf("%s: %d bytes, labels: %v\n", fn.Name, fn.Size, fn.Labels)
+func printCodeDiff(img *asm.Image, gt map[string][]byte) {
-		}
-		return 0
-	}
-
-	fmt.Printf("%s: %d functions assembled\n", path, len(img.Funcs))
-	for _, fn := range img.Funcs {
-		fmt.Printf("  %s: %d bytes\n", fn.Name, fn.Size)
-	}
-	return 0
-}
-
-// cmdVerifyLOONG64 verifies a loong64 source file against `go tool asm`
-// (GOARCH=loong64) — the ground-truth oracle — since gasm cannot JIT-load
-// LoongArch code on an amd64 host.  Relocation sites are masked before the
-// byte comparison, as the toolchain leaves them zero for the linker.
-func cmdVerifyLOONG64(path string, groundTruth, profile bool) int {
-	src, err := readSource(path)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "gasm verify: %v\n", err)
-		return 1
-	}
-	f, errs := parser.Parse(path, src)
-	for _, e := range errs {
-		fmt.Fprintf(os.Stderr, "%s: %v\n", path, e)
-	}
-	if len(errs) > 0 {
-		return 1
-	}
-	img, err := asm.AssembleFileLOONG64(f)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "gasm verify: %v\n", err)
-		return 1
-	}
-
-	if groundTruth {
-		gt, err := verify.GroundTruthLOONG64(path)
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "gasm verify: ground truth: %v\n", err)
-			return 1
-		}
-		matched, total := 0, 0
 	for _, fn := range img.Funcs {
 		gasmCode := img.Code[fn.Offset : fn.Offset+fn.Size]
 		goCode, ok := gt[fn.Name]
-			if !ok {
+		if !ok || bytes.Equal(gasmCode, goCode) {
-				fmt.Printf("  %s: SKIP (not in go tool asm output)\n", fn.Name)
 			continue
 		}
-			total++
-			gasmCmp := make([]byte, len(gasmCode))
-			goCmp := make([]byte, len(goCode))
-			copy(gasmCmp, gasmCode)
-			copy(goCmp, goCode)
-			for _, r := range fn.Relocs {
-				for j := r.Off; j < r.Off+4 && j < len(gasmCmp); j++ {
-					gasmCmp[j] = 0
-				}
-				for j := r.Off; j < r.Off+4 && j < len(goCmp); j++ {
-					goCmp[j] = 0
-				}
-			}
-			if bytes.Equal(gasmCmp, goCmp) {
-				matched++
-				if len(fn.Relocs) > 0 {
-					fmt.Printf("  %s: MATCH (%d bytes, %d relocs masked)\n", fn.Name, fn.Size, len(fn.Relocs))
-				} else {
-					fmt.Printf("  %s: MATCH (%d bytes)\n", fn.Name, fn.Size)
-				}
-			} else {
-				fmt.Printf("  %s: MISMATCH (%d vs %d bytes)\n", fn.Name, fn.Size, len(goCode))
 		for i := 0; i < len(gasmCode) || i < len(goCode); i += 16 {
 			var gb, gs string
 			for j := i; j < i+16 && j < len(gasmCode); j++ {
@@ -928,121 +949,12 @@ func cmdVerifyLOONG64(path string, groundTruth, profile bool) int {
 		}
 	}
 }
-		fmt.Printf("%s: %d/%d matched\n", path, matched, total)
-		if matched < total {
-			return 1
-		}
-		return 0
-	}
-
-	if profile {
-		for _, fn := range img.Funcs {
-			fmt.Printf("%s: %d bytes, labels: %v\n", fn.Name, fn.Size, fn.Labels)
-		}
-		return 0
-	}
-
-	fmt.Printf("%s: %d functions assembled\n", path, len(img.Funcs))
-	for _, fn := range img.Funcs {
-		fmt.Printf("  %s: %d bytes\n", fn.Name, fn.Size)
-	}
-	return 0
-}
-
-func cmdVerifyARM64(path string, groundTruth, profile bool) int {
-	src, err := readSource(path)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "gasm verify: %v\n", err)
-		return 1
-	}
-	f, errs := parser.Parse(path, src)
-	for _, e := range errs {
-		fmt.Fprintf(os.Stderr, "%s: %v\n", path, e)
-	}
-	if len(errs) > 0 {
-		return 1
-	}
-	img, err := asm.AssembleFileARM64(f)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "gasm verify: %v\n", err)
-		return 1
-	}
-
-	if groundTruth {
-		gt, err := verify.GroundTruthARM64(path)
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "gasm verify: ground truth: %v\n", err)
-			return 1
-		}
-		matched, total := 0, 0
-		for _, fn := range img.Funcs {
-			gasmCode := img.Code[fn.Offset : fn.Offset+fn.Size]
-			goCode, ok := gt[fn.Name]
-			if !ok {
-				fmt.Printf("  %s: SKIP (not in go tool asm output)\n", fn.Name)
-				continue
-			}
-			total++
-			gasmCmp := make([]byte, len(gasmCode))
-			goCmp := make([]byte, len(goCode))
-			copy(gasmCmp, gasmCode)
-			copy(goCmp, goCode)
-			for _, r := range fn.Relocs {
-				for j := r.Off; j < r.Off+4 && j < len(gasmCmp); j++ {
-					gasmCmp[j] = 0
-				}
-				for j := r.Off; j < r.Off+4 && j < len(goCmp); j++ {
-					goCmp[j] = 0
-				}
-			}
-			if bytes.Equal(gasmCmp, goCmp) {
-				matched++
-				if len(fn.Relocs) > 0 {
-					fmt.Printf("  %s: MATCH (%d bytes, %d relocs masked)\n", fn.Name, fn.Size, len(fn.Relocs))
-				} else {
-					fmt.Printf("  %s: MATCH (%d bytes)\n", fn.Name, fn.Size)
-				}
-			} else {
-				fmt.Printf("  %s: MISMATCH (%d vs %d bytes)\n", fn.Name, fn.Size, len(goCode))
-				for i := 0; i < len(gasmCode) || i < len(goCode); i += 16 {
-					var gb, gs string
-					for j := i; j < i+16 && j < len(gasmCode); j++ {
-						gb += fmt.Sprintf(" %02x", gasmCode[j])
-					}
-					for j := i; j < i+16 && j < len(goCode); j++ {
-						gs += fmt.Sprintf(" %02x", goCode[j])
-					}
-					fmt.Printf("    %04x: gasm:%s\n", i, gb)
-					fmt.Printf("    %04x: gt:  %s\n", i, gs)
-				}
-			}
-		}
-		fmt.Printf("%s: %d/%d matched\n", path, matched, total)
-		if matched < total {
-			return 1
-		}
-		return 0
-	}
-
-	if profile {
-		for _, fn := range img.Funcs {
-			fmt.Printf("%s: %d bytes, labels: %v\n", fn.Name, fn.Size, fn.Labels)
-		}
-		return 0
-	}
-
-	fmt.Printf("%s: %d functions assembled\n", path, len(img.Funcs))
-	for _, fn := range img.Funcs {
-		fmt.Printf("  %s: %d bytes\n", fn.Name, fn.Size)
-	}
-	return 0
-}
 
 func cmdVerify(args []string) int {
 	set := newCommand("verify", "gasm verify [-smoke] [-abi] [-fuzz] [-ground-truth] [-profile] [-call] <file.s>", `
 Assemble FILE (amd64), map it into executable memory and report the available
 functions.  This confirms the assembled image is self-consistent (no
-unresolved external symbols) and executable — the prerequisite for dynamic
+unresolved external symbols) and executable, the prerequisite for dynamic
 testing.
 
 With -smoke, each NOSPLIT function is called with a zeroed argument block to
@@ -1100,17 +1012,12 @@ each entry reproduces.
 	// under the available loong64 emulators), so those kernels take the
 	// toolchain-comparison path.
 	if targetArch != hostArch() || targetArch == arch.LOONG64 {
+		// No JIT on this host: ground truth and profile remain available.
+		// (loong64 is ground-truth-only everywhere for now: its trampoline
+		// is implemented but not yet validated against real hardware.)
 		switch targetArch {
-		case arch.RISCV:
+		case arch.RISCV, arch.LOONG64, arch.ARM64:
-			// RISC-V: ground-truth only (no JIT on non-RISC-V hosts).
+			return cmdVerifyNonJIT(path, targetArch, *groundTruth, *profile)
-			return cmdVerifyRISCV(path, *groundTruth, *profile)
-		case arch.LOONG64:
-			// LoongArch: ground-truth only (trampoline not yet
-			// hardware-validated).
-			return cmdVerifyLOONG64(path, *groundTruth, *profile)
-		case arch.ARM64:
-			// AArch64: ground-truth only (no JIT on non-ARM64 hosts).
-			return cmdVerifyARM64(path, *groundTruth, *profile)
 		case arch.AMD64:
 			fmt.Fprintln(os.Stderr, "gasm verify: JIT-based checks need an amd64 host; use --ground-truth here")
 			return 1
@@ -1224,50 +1131,13 @@ each entry reproduces.
 			fmt.Fprintf(os.Stderr, "gasm verify: ground truth: %v\n", err)
 			return 1
 		}
-		matched, total := 0, 0
+		matched, total, diffs := compareGroundTruth(k.Image(), gt)
-		for _, name := range names {
+		if diffs > 0 {
-			fl, _ := k.Func(name)
+			printCodeDiff(k.Image(), gt)
-			gasmCode := k.Image().Code[fl.Offset : fl.Offset+fl.Size]
-			goCode, ok := gt[name]
-			if !ok {
-				fmt.Printf("  %s: SKIP (not in go tool asm output)\n", name)
-				continue
-			}
-			total++
-			// Compare, masking relocation sites (disp32 fields that the
-			// Go linker fills at link time — gasm resolves them internally).
-			gasmCmp := make([]byte, len(gasmCode))
-			goCmp := make([]byte, len(goCode))
-			copy(gasmCmp, gasmCode)
-			copy(goCmp, goCode)
-			for _, r := range fl.Relocs {
-				for j := r.Off; j < r.Off+4 && j < len(gasmCmp); j++ {
-					gasmCmp[j] = 0
-				}
-				for j := r.Off; j < r.Off+4 && j < len(goCmp); j++ {
-					goCmp[j] = 0
-				}
-			}
-			if bytes.Equal(gasmCmp, goCmp) {
-				matched++
-				if len(fl.Relocs) > 0 {
-					fmt.Printf("  %s: MATCH (%d bytes, %d relocs masked)\n", name, fl.Size, len(fl.Relocs))
-				} else {
-					fmt.Printf("  %s: MATCH (%d bytes)\n", name, fl.Size)
-				}
-			} else {
-				fmt.Printf("  %s: MISMATCH (gasm %d bytes, go %d bytes)\n", name, fl.Size, len(goCode))
-				for i := 0; i < len(gasmCmp) && i < len(goCmp); i++ {
-					if gasmCmp[i] != goCmp[i] {
-						fmt.Printf("    first diff at byte %d: gasm=%02x go=%02x\n", i, gasmCmp[i], goCmp[i])
-						break
-					}
-				}
 			rc = 1
 		}
-		}
 		fmt.Printf("ground truth: %d/%d functions byte-identical\n", matched, total)
-		if matched < total {
+		if matched < total || diffs > 0 {
 			rc = 1
 		}
 	}
@@ -1289,13 +1159,11 @@ each entry reproduces.
 		sigs := verify.ExtractSignatures(src)
 		fuzzed := 0
 		for _, name := range names {
-			sig, ok := sigs[name]
+			if _, ok := sigs[name]; !ok {
-			if !ok {
 				fmt.Printf("  %s: SKIP (no // func signature)\n", name)
 				continue
 			}
-			goCode, ok := gt[name]
+			if _, ok := gt[name]; !ok {
-			if !ok {
 				fmt.Printf("  %s: SKIP (not in go tool asm output)\n", name)
 				continue
 			}
@@ -1312,8 +1180,6 @@ each entry reproduces.
 					rc = 1
 				}
 			}
-			_ = sig
-			_ = goCode
 			fuzzed++
 		}
 		fmt.Printf("fuzz: %d functions tested, %d iterations each\n", fuzzed, *fuzzN)
@@ -1338,7 +1204,7 @@ each entry reproduces.
 
 	// Run smoke and ABI checks in parallel, each function in its own child
 	// process: the JIT'd code runs with zeroed or fuzzed arguments, and a
-	// function that dereferences them faults — the crash is reported as a
+	// function that dereferences them faults, the crash is reported as a
 	// CRASH line instead of killing this process (mirrors fuzzInSubprocess).
 	if *smoke || *abi {
 		type checkResult struct {
@@ -1479,7 +1345,7 @@ func fuzzInSubprocess(path, funcName string, n int, extra ...string) string {
 		if exitErr, ok := err.(*exec.ExitError); ok {
 			ws := exitErr.Sys().(syscall.WaitStatus)
 			if ws.Signaled() {
-				return fmt.Sprintf("%s: CRASH (%v — partial function, use --ground-truth)", funcName, ws.Signal())
+				return fmt.Sprintf("%s: CRASH (%v; partial function, use --ground-truth)", funcName, ws.Signal())
 			}
 		}
 		// Non-zero exit without a signal: the fuzz reported mismatches.
@@ -1504,12 +1370,12 @@ func fuzzInSubprocess(path, funcName string, n int, extra ...string) string {
 // sweepInSubprocess runs the smoke/abi checks for a single function in a
 // child process.  If the child is killed by a signal (e.g. SIGSEGV from a
 // function that dereferences its zeroed or fuzzed arguments), it returns a
-// CRASH report instead of dying — the same isolation fuzzInSubprocess
+// CRASH report instead of dying, the same isolation fuzzInSubprocess
 // provides for the fuzz sweep.
 func sweepInSubprocess(path, funcName string, smoke, abi bool, abiN int) (string, bool) {
 	self, err := os.Executable()
 	if err != nil {
-		return fmt.Sprintf("    smoke/abi: FAIL — cannot find self: %v", err), true
+		return fmt.Sprintf("    smoke/abi: FAIL: cannot find self: %v", err), true
 	}
 	args := []string{"verify"}
 	if smoke {
@@ -1526,7 +1392,7 @@ func sweepInSubprocess(path, funcName string, smoke, abi bool, abiN int) (string
 		if exitErr, ok := err.(*exec.ExitError); ok {
 			ws, ok := exitErr.Sys().(syscall.WaitStatus)
 			if ok && ws.Signaled() {
-				return fmt.Sprintf("    smoke/abi: CRASH (%v — the function faults on zeroed or fuzzed\n    arguments; verify it with -call and valid buffers)", ws.Signal()), true
+				return fmt.Sprintf("    smoke/abi: CRASH (%v: the function faults on zeroed or fuzzed\n    arguments; verify it with -call and valid buffers)", ws.Signal()), true
 			}
 		}
 		// Non-zero exit without a signal: the checks themselves failed and
@@ -1550,7 +1416,7 @@ func sweepCheckLines(out []byte) string {
 }
 
 // runSweepChecks performs the in-process smoke and ABI checks for one
-// function — the child half of sweepInSubprocess.
+// function, the child half of sweepInSubprocess.
 func runSweepChecks(k *verify.Kernel, path, name string, fl asm.FuncLayout, smoke, abi bool, abiN int) ([]string, bool) {
 	var msgs []string
 	failed := false
@@ -1559,7 +1425,7 @@ func runSweepChecks(k *verify.Kernel, path, name string, fl asm.FuncLayout, smok
 		args := make([]byte, fl.Args)
 		_, err := k.CallFunc(name, args)
 		if err != nil {
-			msgs = append(msgs, fmt.Sprintf("    smoke: FAIL — %v", err))
+			msgs = append(msgs, fmt.Sprintf("    smoke: FAIL: %v", err))
 			failed = true
 		} else {
 			msgs = append(msgs, "    smoke: OK")
@@ -1579,7 +1445,7 @@ func runSweepChecks(k *verify.Kernel, path, name string, fl asm.FuncLayout, smok
 			args := make([]byte, fl.Args)
 			_, report, err := k.CallFuncChecked(name, args)
 			if err != nil {
-				msgs = append(msgs, fmt.Sprintf("    abi: FAIL — %v", err))
+				msgs = append(msgs, fmt.Sprintf("    abi: FAIL: %v", err))
 				failed = true
 			} else if !report.OK() {
 				msgs = append(msgs, fmt.Sprintf("    abi: %s", report))
@@ -1669,7 +1535,7 @@ func cmdVerifyCall(k *verify.Kernel, path, funcName, bufSpec, scalarSpec string,
 	for i := range repeat {
 		out, err := k.CallFunc(funcName, args)
 		if err != nil {
-			fmt.Printf("  call %d: FAIL — %v\n", i+1, err)
+			fmt.Printf("  call %d: FAIL: %v\n", i+1, err)
 			rc = 1
 			continue
 		}

cmd/gasm/main_test.go

@@ -219,8 +219,9 @@ func TestCmdVersion(t *testing.T) {
 	if code != 0 {
 		t.Fatalf("code = %d", code)
 	}
-	if !strings.Contains(out, version) {
+	got := version()
-		t.Errorf("version output %q does not mention %q", out, version)
+	if !strings.Contains(out, got) {
+		t.Errorf("version output %q does not mention %q", out, got)
 	}
 }
 
@@ -274,7 +275,7 @@ func TestVerifySmokeCrashIsolation(t *testing.T) {
 	}
 	if exitErr, ok := err.(*exec.ExitError); ok {
 		if ws, ok := exitErr.Sys().(syscall.WaitStatus); ok && ws.Signaled() {
-			t.Fatalf("verify died from %v — the crash was not isolated:\n%s", ws.Signal(), out)
+			t.Fatalf("verify died from %v; the crash was not isolated:\n%s", ws.Signal(), out)
 		}
 	}
 	if !strings.Contains(string(out), "CRASH") {
@@ -292,3 +293,58 @@ func TestSweepCheckLines(t *testing.T) {
 		t.Errorf("sweepCheckLines = %q, want %q", got, want)
 	}
 }
+
+// TestRunCorpusAudit drives the corpus audit over a small fixture tree: one
+// suffixed amd64 file, one suffixed arm64 file whose body is not arm64, one
+// generic file, and one file that does not parse.
+func TestRunCorpusAudit(t *testing.T) {
+	dir := t.TempDir()
+	write := func(name, src string) {
+		t.Helper()
+		if err := os.WriteFile(filepath.Join(dir, name), []byte(src), 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+	write("good_amd64.s", "#include \"textflag.h\"\nTEXT ·add(SB), NOSPLIT, $0-0\n\tMOVQ AX, BX\n\tRET\n")
+	write("bad_arm64.s", "#include \"textflag.h\"\nTEXT ·f(SB), NOSPLIT, $0-0\n\tMOVQ AX, BX\n\tRET\n")
+	write("generic.s", "#include \"textflag.h\"\nTEXT ·g(SB), NOSPLIT, $0-0\n\tRET\n")
+	write("broken.s", "#include \"textflag.h\"\nTEXT ·b(SB), NOSPLIT, $0-0\n\tJMP nowhere\n\tRET\n")
+
+	stats, err := runCorpusAudit(dir)
+	if err != nil {
+		t.Fatalf("runCorpusAudit: %v", err)
+	}
+	if stats.files != 4 {
+		t.Errorf("files = %d, want 4", stats.files)
+	}
+	if stats.generic != 2 {
+		t.Errorf("generic = %d, want 2 (generic.s and broken.s)", stats.generic)
+	}
+	// good_amd64 and generic.s assemble everywhere they are attempted.
+	if stats.full != 2 {
+		t.Errorf("full = %d, want 2", stats.full)
+	}
+	get := func(name string) *corpusTally {
+		for i, tg := range stats.targets {
+			if tg.name == name {
+				return stats.tallies[i]
+			}
+		}
+		t.Fatalf("no tally for %s", name)
+		return nil
+	}
+	// amd64: good_amd64 + generic.s + broken.s; the broken file fails to parse.
+	if a := get("amd64"); a.attempted != 3 || a.assembled != 2 {
+		t.Errorf("amd64 = %d/%d, want 2/3", a.assembled, a.attempted)
+	}
+	// arm64: bad_arm64 (MOVQ is not arm64) + generic.s + broken.s.
+	if a := get("arm64"); a.attempted != 3 || a.assembled != 1 {
+		t.Errorf("arm64 = %d/%d, want 1/3", a.assembled, a.attempted)
+	}
+	if r := get("amd64").reasons["instruction not encodable"]; r != 0 {
+		t.Errorf("amd64 unexpected unencodable reason: %d", r)
+	}
+	if r := get("arm64").reasons["instruction not encodable"]; r != 1 {
+		t.Errorf("arm64 unencodable reasons = %d, want 1", r)
+	}
+}

cmd/gasm/man_test.go

@@ -0,0 +1,157 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+package main
+
+import (
+	"os"
+	"os/exec"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"testing"
+)
+
+// TestManPagesTrackTheCLI builds the binary once, then compares every
+// command's live `-h` output with its docs/man/gasm-<command>.1 page: the
+// flag sets must agree both ways, and the page's SYNOPSIS line must carry
+// the command's usage line.  A flag or a usage change that skips the man
+// page fails here, so the pages cannot drift from the binary.
+func TestManPagesTrackTheCLI(t *testing.T) {
+	if testing.Short() {
+		t.Skip("builds the gasm binary")
+	}
+	bin := filepath.Join(t.TempDir(), "gasm")
+	if out, err := exec.Command("go", "build", "-o", bin, ".").CombinedOutput(); err != nil {
+		t.Fatalf("build gasm: %v\n%s", err, out)
+	}
+
+	for _, cmd := range []string{
+		"tokens", "parse", "fmt", "lint", "asm", "dis", "verify",
+		"debug", "diff", "profile", "audit-instructions", "scaffold", "lsp",
+	} {
+		t.Run(cmd, func(t *testing.T) {
+			raw, err := os.ReadFile(filepath.Join("..", "..", "docs", "man", "gasm-"+cmd+".1"))
+			if err != nil {
+				t.Fatalf("read man page: %v", err)
+			}
+			page := string(raw)
+
+			out, _ := exec.Command(bin, cmd, "-h").CombinedOutput()
+			help := string(out)
+
+			binFlags := helpFlags(help)
+			pageFlags := roffFlags(page)
+			for f := range binFlags {
+				if !pageFlags[f] {
+					t.Errorf("flag -%s is in the binary's help but missing from the man page", f)
+				}
+			}
+			for f := range pageFlags {
+				if !binFlags[f] {
+					t.Errorf("flag -%s is in the man page but the binary does not accept it", f)
+				}
+			}
+
+			want := helpUsage(help)
+			got := roffSynopsis(page)
+			if want != "" && got != want {
+				t.Errorf("SYNOPSIS drift:\n page: %s\nbinary: %s", got, want)
+			}
+		})
+	}
+}
+
+// helpFlags extracts the flag names from a `gasm <cmd> -h` output.
+func helpFlags(help string) map[string]bool {
+	m := map[string]bool{}
+	inFlags := false
+	for line := range strings.SplitSeq(help, "\n") {
+		if strings.TrimRight(line, " \t") == "Flags:" {
+			inFlags = true
+			continue
+		}
+		if !inFlags {
+			continue
+		}
+		if !strings.HasPrefix(line, "  -") {
+			continue
+		}
+		token := strings.FieldsFunc(strings.TrimLeft(line, " "), func(r rune) bool {
+			return r == ' ' || r == '\t'
+		})
+		if len(token) == 0 {
+			continue
+		}
+		m[strings.TrimLeft(token[0], "-")] = true
+	}
+	return m
+}
+
+var roffEscape = regexp.MustCompile(`\\f[BIRP]`)
+
+// roffFlags extracts the flag names from a man page's OPTIONS section.
+func roffFlags(page string) map[string]bool {
+	m := map[string]bool{}
+	inOptions := false
+	for line := range strings.SplitSeq(page, "\n") {
+		if strings.HasPrefix(line, ".SH ") {
+			inOptions = strings.HasPrefix(line, ".SH OPTIONS")
+			continue
+		}
+		if !inOptions {
+			continue
+		}
+		// Flag entries are written as either `.B \-flag` or `\fB\-flag`.
+		var body string
+		switch {
+		case strings.HasPrefix(line, `.B \-`):
+			body = line[3:]
+		case strings.HasPrefix(line, `\fB\-`):
+			body = line[1:]
+		default:
+			continue
+		}
+		name := roffEscape.ReplaceAllString(body, "")
+		name = strings.ReplaceAll(name, `\-`, "-")
+		name = strings.TrimSpace(name)
+		if i := strings.IndexAny(name, " \t"); i >= 0 {
+			name = name[:i]
+		}
+		m[strings.TrimLeft(name, "-")] = true
+	}
+	return m
+}
+
+// helpUsage returns the command's usage line without the "Usage: " prefix.
+func helpUsage(help string) string {
+	for line := range strings.SplitSeq(help, "\n") {
+		if strings.HasPrefix(line, "Usage: ") {
+			return normaliseUsage(line[len("Usage: "):])
+		}
+	}
+	return ""
+}
+
+// roffSynopsis returns the page's SYNOPSIS usage line, unescaped.
+func roffSynopsis(page string) string {
+	inSyn := false
+	for line := range strings.SplitSeq(page, "\n") {
+		if strings.HasPrefix(line, ".SH ") {
+			inSyn = strings.HasPrefix(line, ".SH SYNOPSIS")
+			continue
+		}
+		if !inSyn || !strings.HasPrefix(line, ".B ") {
+			continue
+		}
+		return normaliseUsage(strings.ReplaceAll(line[3:], `\-`, "-"))
+	}
+	return ""
+}
+
+// normaliseUsage flattens whitespace and drops the roff font escapes so that
+// the binary's usage line and the page's SYNOPSIS line compare equal.
+func normaliseUsage(s string) string {
+	s = roffEscape.ReplaceAllString(s, "")
+	return strings.Join(strings.Fields(s), " ")
+}

cmd/gasm/scaffold.go

@@ -19,7 +19,7 @@ import (
 // file: a Go test that seeds random states, drives both the assembly kernel
 // and a caller-provided portable reference, and compares the outputs
 // byte-for-byte.  The lesson this encodes: a pipeline-level fuzz cannot see
-// an unwired kernel — only a direct-call differential against the portable
+// an unwired kernel, only a direct-call differential against the portable
 // specification can, so every kernel ships with one.
 //
 // The generated file follows two conventions the caller fills in:

cmd/gasm/unidiff.go

@@ -0,0 +1,140 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+package main
+
+import (
+	"fmt"
+	"slices"
+	"strings"
+)
+
+// unifiedDiff renders a unified diff with three lines of context between the
+// two line slices, in the form `gofmt -d` prints.  An empty result means the
+// inputs are identical.
+func unifiedDiff(name string, a, b []string) string {
+	if slices.Equal(a, b) {
+		return ""
+	}
+	var out strings.Builder
+	fmt.Fprintf(&out, "--- %s\n+++ %s\n", name, name)
+
+	// Longest common subsequence over the lines (assembly files are small
+	// enough for the quadratic table).
+	n, m := len(a), len(b)
+	lcs := make([][]int, n+1)
+	for i := range lcs {
+		lcs[i] = make([]int, m+1)
+	}
+	for i := n - 1; i >= 0; i-- {
+		for j := m - 1; j >= 0; j-- {
+			if a[i] == b[j] {
+				lcs[i][j] = lcs[i+1][j+1] + 1
+			} else if lcs[i+1][j] >= lcs[i][j+1] {
+				lcs[i][j] = lcs[i+1][j]
+			} else {
+				lcs[i][j] = lcs[i][j+1]
+			}
+		}
+	}
+
+	// Walk the LCS once, assigning every op its absolute position in both
+	// files (1-based, the position an insertion sits before).
+	type op struct {
+		kind         byte // ' ', '-' or '+'
+		aLine, bLine int
+		text         string
+	}
+	var ops []op
+	aPos, bPos := 0, 0
+	emit := func(kind byte, text string) {
+		ops = append(ops, op{kind: kind, aLine: aPos + 1, bLine: bPos + 1, text: text})
+		switch kind {
+		case ' ':
+			aPos++
+			bPos++
+		case '-':
+			aPos++
+		case '+':
+			bPos++
+		}
+	}
+	i, j := 0, 0
+	for i < n && j < m {
+		switch {
+		case a[i] == b[j]:
+			emit(' ', a[i])
+			i++
+			j++
+		case lcs[i+1][j] >= lcs[i][j+1]:
+			emit('-', a[i])
+			i++
+		default:
+			emit('+', b[j])
+			j++
+		}
+	}
+	for ; i < n; i++ {
+		emit('-', a[i])
+	}
+	for ; j < m; j++ {
+		emit('+', b[j])
+	}
+
+	// Group the edits into hunks: consecutive changes separated by more than
+	// twice the context lines start a new hunk.
+	const context = 3
+	var changes []int
+	for k, o := range ops {
+		if o.kind != ' ' {
+			changes = append(changes, k)
+		}
+	}
+	for g := 0; g < len(changes); {
+		last := g
+		for last+1 < len(changes) && changes[last+1]-changes[last]-1 <= 2*context {
+			last++
+		}
+		lo := max(0, changes[g]-context)
+		hi := min(len(ops), changes[last]+1+context)
+		// The header numbers are the first line of each side actually shown:
+		// the first context, deletion or insertion line.  A hunk that shows
+		// no old lines is a pure insertion and reports the position it sits
+		// before (0 at the top of the file); the mirror rule holds for a
+		// pure deletion.
+		aStart := ops[lo].aLine - 1
+		bStart := ops[lo].bLine - 1
+		countA, countB := 0, 0
+		for _, o := range ops[lo:hi] {
+			switch o.kind {
+			case ' ':
+				countA++
+				countB++
+			case '-':
+				countA++
+			case '+':
+				countB++
+			}
+		}
+		for _, o := range ops[lo:hi] {
+			if o.kind != '+' {
+				aStart = o.aLine
+				break
+			}
+		}
+		for _, o := range ops[lo:hi] {
+			if o.kind != '-' {
+				bStart = o.bLine
+				break
+			}
+		}
+		fmt.Fprintf(&out, "@@ -%d,%d +%d,%d @@\n", aStart, countA, bStart, countB)
+		for _, o := range ops[lo:hi] {
+			out.WriteByte(o.kind)
+			out.WriteString(o.text)
+			out.WriteByte('\n')
+		}
+		g = last + 1
+	}
+	return out.String()
+}

cmd/gasm/unidiff_test.go

@@ -0,0 +1,94 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+package main
+
+import (
+	"slices"
+	"strings"
+	"testing"
+)
+
+func lines(ss ...string) []string { return ss }
+
+func TestUnifiedDiffIdentical(t *testing.T) {
+	if got := unifiedDiff("f", lines("a", "b"), lines("a", "b")); got != "" {
+		t.Errorf("identical inputs produced %q, want empty", got)
+	}
+}
+
+func TestUnifiedDiffSingleChange(t *testing.T) {
+	a := lines("1", "2", "3", "4", "5", "6", "7", "8")
+	b := lines("1", "2", "3!", "4", "5", "6", "7", "8")
+	want := "--- f\n+++ f\n" +
+		"@@ -1,6 +1,6 @@\n" +
+		" 1\n 2\n-3\n+3!\n 4\n 5\n 6\n"
+	if got := unifiedDiff("f", a, b); got != want {
+		t.Errorf("diff = %q, want %q", got, want)
+	}
+}
+
+func TestUnifiedDiffInsertAtStart(t *testing.T) {
+	got := unifiedDiff("f", lines("x"), lines("new", "x"))
+	// The single existing line is shown as trailing context, so the hunk
+	// covers it.
+	want := "--- f\n+++ f\n@@ -1,1 +1,2 @@\n+new\n x\n"
+	if got != want {
+		t.Errorf("diff = %q, want %q", got, want)
+	}
+}
+
+func TestUnifiedDiffDeleteAtEnd(t *testing.T) {
+	got := unifiedDiff("f", lines("x", "y"), lines("x"))
+	want := "--- f\n+++ f\n@@ -1,2 +1,1 @@\n x\n-y\n"
+	if got != want {
+		t.Errorf("diff = %q, want %q", got, want)
+	}
+}
+
+func TestUnifiedDiffTwoHunks(t *testing.T) {
+	var a, b []string
+	for i := 1; i <= 20; i++ {
+		a = append(a, itoa(i))
+		b = append(b, itoa(i))
+	}
+	b[1] = "2!"
+	b[17] = "18!"
+	got := unifiedDiff("f", a, b)
+	if !strings.Contains(got, "@@ -1,5 +1,5 @@\n 1\n-2\n+2!\n 3\n 4\n 5\n") {
+		t.Errorf("first hunk wrong:\n%s", got)
+	}
+	if !strings.Contains(got, "@@ -15,6 +15,6 @@\n 15\n 16\n 17\n-18\n+18!\n 19\n 20\n") {
+		t.Errorf("second hunk wrong:\n%s", got)
+	}
+}
+
+// TestUnifiedDiffAdjacentHunks merges changes separated by exactly twice the
+// context into one hunk.
+func TestUnifiedDiffAdjacentHunks(t *testing.T) {
+	a := lines("1", "2", "3", "4", "5", "6", "7", "8")
+	b := slices.Clone(a)
+	b[0] = "1!"
+	b[7] = "8!"
+	got := unifiedDiff("f", a, b)
+	want := "--- f\n+++ f\n" +
+		"@@ -1,8 +1,8 @@\n" +
+		"-1\n+1!\n 2\n 3\n 4\n 5\n 6\n 7\n-8\n+8!\n"
+	if got != want {
+		t.Errorf("diff = %q, want %q", got, want)
+	}
+}
+
+func itoa(n int) string {
+	if n == 0 {
+		return "0"
+	}
+	var buf [4]byte
+	i := len(buf)
+	for n > 0 {
+		i--
+		buf[i] = byte('0' + n%10)
+		n /= 10
+	}
+	return string(buf[i:])
+}

debug/breakpoint.go

@@ -36,7 +36,7 @@ type Condition struct {
 func (c *Condition) Eval(regs *Regs) bool {
 	actual, ok := regs.RegValue(c.Reg)
 	if !ok {
-		return true // unknown register — don't block
+		return true // unknown register, don't block
 	}
 	var expected uint64
 	switch {
@@ -48,7 +48,7 @@ func (c *Condition) Eval(regs *Regs) bool {
 		}
 		expected = v
 	case c.MemAddr != 0:
-		// Register-memory comparison — requires a Session, not available here.
+		// Register-memory comparison, requires a Session, not available here.
 		// Fall back to treating as constant (the caller should resolve).
 		expected = c.Value
 	default:
@@ -72,8 +72,7 @@ func (c *Condition) Eval(regs *Regs) bool {
 	}
 }
 
-// Breakpoints manages the set of breakpoints for a Session.
+// Breakpoints manages the software breakpoints of one Session.
-// Breakpoints manages software breakpoints for a debuggee.
 type Breakpoints struct {
 	t   tracer
 	bps map[uint64]*Breakpoint
@@ -200,7 +199,7 @@ func (bm *Breakpoints) HandleTrap(regs *Regs) *Breakpoint {
 	}
 	// Check the condition (if any).
 	if bp.Cond != nil && !bp.Cond.Eval(regs) {
-		// Condition not met — restore the byte but do NOT rewind RIP.
+		// Condition not met, restore the byte but do NOT rewind RIP.
 		// The process continues from the next instruction (past the INT3).
 		word, err := bm.t.Peek(trapAddr)
 		if err == nil {

debug/debug_test.go

@@ -275,8 +275,7 @@ func TestBreakpointInfo(t *testing.T) {
 }
 
 func TestWatchpointSlotTracking(t *testing.T) {
-	wpSlots = [4]bool{} // reset
+	s := &Session{} // per-session slots start free
-	s := &Session{}
 
 	// All four slots are free initially.
 	for i := range 4 {
@@ -289,8 +288,8 @@ func TestWatchpointSlotTracking(t *testing.T) {
 	}
 
 	// Manually mark slots 0 and 2 as used (simulating successful SetWatchpoint).
-	wpSlots[0] = true
+	s.wpSlots[0] = true
-	wpSlots[2] = true
+	s.wpSlots[2] = true
 
 	if !s.IsWatchpointSlotUsed(0) {
 		t.Error("slot 0 should be in use")
@@ -318,7 +317,7 @@ func TestWatchpointSlotTracking(t *testing.T) {
 
 	// Mark all slots used: FindFreeWatchpointSlot returns -1.
 	for i := range 4 {
-		wpSlots[i] = true
+		s.wpSlots[i] = true
 	}
 	if got := s.FindFreeWatchpointSlot(); got != -1 {
 		t.Errorf("FindFreeWatchpointSlot() with all slots used = %d, want -1", got)

debug/disasm_linux_amd64.go

@@ -9,27 +9,22 @@ import (
 	"fmt"
 	"strings"
 
-	"golang.org/x/arch/x86/x86asm"
+	"sourcedock.dev/petrbalvin/gasm-devkit/arch"
+	"sourcedock.dev/petrbalvin/gasm-devkit/disasm"
 )
 
 // Disassemble decodes the instruction at the given address in the debuggee's
 // memory and returns its text representation and length in bytes.
 func (s *Session) Disassemble(addr uint64) (string, int, error) {
-	// Read up to 15 bytes (max x86 instruction length).
 	mem, err := s.ReadMemory(addr, 15)
-	if err != nil {
-		// Try a shorter read if we're near a page boundary.
-		mem, err = s.ReadMemory(addr, 1)
 	if err != nil {
 		return "", 0, err
 	}
-	}
+	ins, err := disasm.Decode(arch.AMD64, mem, addr)
-	inst, err := x86asm.Decode(mem, 64)
 	if err != nil {
-		return "???", 1, nil
+		return "", 0, err
 	}
-	text := x86asm.IntelSyntax(inst, addr, nil)
+	return ins.Text, ins.Len, nil
-	return text, inst.Len, nil
 }
 
 // DisassembleN decodes up to n instructions starting at addr and returns

debug/disasm_linux_arm64.go

@@ -8,7 +8,8 @@ package debug
 import (
 	"fmt"
 
-	"golang.org/x/arch/arm64/arm64asm"
+	"sourcedock.dev/petrbalvin/gasm-devkit/arch"
+	"sourcedock.dev/petrbalvin/gasm-devkit/disasm"
 )
 
 // Disassemble decodes the instruction at the given address in the debuggee's
@@ -18,12 +19,11 @@ func (s *Session) Disassemble(addr uint64) (string, int, error) {
 	if err != nil {
 		return "", 0, err
 	}
-	inst, err := arm64asm.Decode(mem)
+	ins, err := disasm.Decode(arch.ARM64, mem, addr)
 	if err != nil {
-		return "???", 4, nil
+		return "", 0, err
 	}
-	text := arm64asm.GoSyntax(inst, addr, nil, nil)
+	return ins.Text, ins.Len, nil
-	return text, 4, nil
 }
 
 // DisassembleN decodes up to n instructions starting at addr.

debug/disasm_linux_loong64.go

@@ -8,7 +8,8 @@ package debug
 import (
 	"fmt"
 
-	"golang.org/x/arch/loong64/loong64asm"
+	"sourcedock.dev/petrbalvin/gasm-devkit/arch"
+	"sourcedock.dev/petrbalvin/gasm-devkit/disasm"
 )
 
 // Disassemble decodes the instruction at the given address in the debuggee's
@@ -18,12 +19,11 @@ func (s *Session) Disassemble(addr uint64) (string, int, error) {
 	if err != nil {
 		return "", 0, err
 	}
-	inst, err := loong64asm.Decode(mem)
+	ins, err := disasm.Decode(arch.LOONG64, mem, addr)
 	if err != nil {
-		return "???", 4, nil
+		return "", 0, err
 	}
-	text := loong64asm.GoSyntax(inst, addr, nil)
+	return ins.Text, ins.Len, nil
-	return text, 4, nil
 }
 
 // DisassembleN decodes up to n instructions starting at addr.

debug/disasm_linux_riscv64.go

@@ -8,7 +8,8 @@ package debug
 import (
 	"fmt"
 
-	"golang.org/x/arch/riscv64/riscv64asm"
+	"sourcedock.dev/petrbalvin/gasm-devkit/arch"
+	"sourcedock.dev/petrbalvin/gasm-devkit/disasm"
 )
 
 // Disassemble decodes the instruction at the given address in the debuggee's
@@ -18,12 +19,11 @@ func (s *Session) Disassemble(addr uint64) (string, int, error) {
 	if err != nil {
 		return "", 0, err
 	}
-	inst, err := riscv64asm.Decode(mem)
+	ins, err := disasm.Decode(arch.RISCV, mem, addr)
 	if err != nil {
-		return "???", 4, nil
+		return "", 0, err
 	}
-	text := riscv64asm.GoSyntax(inst, addr, nil, nil)
+	return ins.Text, ins.Len, nil
-	return text, inst.Len, nil
 }
 
 // DisassembleN decodes up to n instructions starting at addr.

debug/ptrace_linux.go

@@ -23,6 +23,7 @@ type Session struct {
 	stopped  bool
 	exited   bool
 	codeBase uint64   // base address of the JIT code in the debuggee
+	wpSlots  [16]bool // hardware watchpoint slots in use (DR0-DR3, arm64 BADVR0-15)
 }
 
 // Launch starts the debuggee subprocess (gasm debug --target ...) and

debug/watchpoint_linux_amd64.go

@@ -20,14 +20,11 @@ const (
 	WatchRead  WatchpointType = 3 // trigger on read or write
 )
 
-// wpSlots tracks watchpoint slot occupancy (DR0-DR3).
-var wpSlots [4]bool
-
 // FindFreeWatchpointSlot returns the index of the first free watchpoint slot
 // (0-3), or -1 if all four hardware watchpoints are in use.
 func (s *Session) FindFreeWatchpointSlot() int {
 	for i := range 4 {
-		if !wpSlots[i] {
+		if !s.wpSlots[i] {
 			return i
 		}
 	}
@@ -39,7 +36,7 @@ func (s *Session) IsWatchpointSlotUsed(slot int) bool {
 	if slot < 0 || slot > 3 {
 		return false
 	}
-	return wpSlots[slot]
+	return s.wpSlots[slot]
 }
 
 // SetWatchpoint installs a hardware watchpoint on the given address.
@@ -47,7 +44,7 @@ func (s *Session) SetWatchpoint(slot int, addr uint64, typ WatchpointType, size
 	if slot < 0 || slot > 3 {
 		return fmt.Errorf("debug: watchpoint slot must be 0-3")
 	}
-	if wpSlots[slot] {
+	if s.wpSlots[slot] {
 		return fmt.Errorf("debug: watchpoint slot %d already in use", slot)
 	}
 
@@ -96,7 +93,7 @@ func (s *Session) SetWatchpoint(slot int, addr uint64, typ WatchpointType, size
 	if err := ptracePokeUser(s.pid, 0x38, dr7); err != nil {
 		return fmt.Errorf("debug: set DR7: %w", err)
 	}
-	wpSlots[slot] = true
+	s.wpSlots[slot] = true
 	return nil
 }
 
@@ -105,7 +102,7 @@ func (s *Session) ClearWatchpoint(slot int) error {
 	if slot < 0 || slot > 3 {
 		return fmt.Errorf("debug: watchpoint slot must be 0-3")
 	}
-	if !wpSlots[slot] {
+	if !s.wpSlots[slot] {
 		return fmt.Errorf("debug: watchpoint slot %d is not in use", slot)
 	}
 	dr7, err := ptracePeekUser(s.pid, 0x38)
@@ -116,14 +113,14 @@ func (s *Session) ClearWatchpoint(slot int) error {
 	if err := ptracePokeUser(s.pid, 0x38, dr7); err != nil {
 		return err
 	}
-	wpSlots[slot] = false
+	s.wpSlots[slot] = false
 	return nil
 }
 
 // ClearAllWatchpoints removes all hardware watchpoints.
 func (s *Session) ClearAllWatchpoints() error {
 	for slot := range 4 {
-		if wpSlots[slot] {
+		if s.wpSlots[slot] {
 			if err := s.ClearWatchpoint(slot); err != nil {
 				return err
 			}

debug/watchpoint_linux_arm64.go

@@ -22,9 +22,6 @@ const (
 	WatchRead  WatchpointType = 3
 )
 
-// wpSlots tracks watchpoint slot occupancy.
-var wpSlots [16]bool // arm64 supports up to 16 watchpoints
-
 const maxWatchpoints = 16
 
 // hwBreakState mirrors the kernel's struct user_hwdebug_state.
@@ -45,7 +42,7 @@ const (
 
 func (s *Session) FindFreeWatchpointSlot() int {
 	for i := range maxWatchpoints {
-		if !wpSlots[i] {
+		if !s.wpSlots[i] {
 			return i
 		}
 	}
@@ -56,7 +53,7 @@ func (s *Session) IsWatchpointSlotUsed(slot int) bool {
 	if slot < 0 || slot >= maxWatchpoints {
 		return false
 	}
-	return wpSlots[slot]
+	return s.wpSlots[slot]
 }
 
 // SetWatchpoint installs a hardware watchpoint on the given address.
@@ -64,7 +61,7 @@ func (s *Session) SetWatchpoint(slot int, addr uint64, typ WatchpointType, size
 	if slot < 0 || slot >= maxWatchpoints {
 		return fmt.Errorf("debug: watchpoint slot must be 0-%d", maxWatchpoints-1)
 	}
-	if wpSlots[slot] {
+	if s.wpSlots[slot] {
 		return fmt.Errorf("debug: watchpoint slot %d already in use", slot)
 	}
 
@@ -105,7 +102,7 @@ func (s *Session) SetWatchpoint(slot int, addr uint64, typ WatchpointType, size
 		return fmt.Errorf("debug: set watchpoint: %w", err)
 	}
 
-	wpSlots[slot] = true
+	s.wpSlots[slot] = true
 	return nil
 }
 
@@ -113,7 +110,7 @@ func (s *Session) ClearWatchpoint(slot int) error {
 	if slot < 0 || slot >= maxWatchpoints {
 		return fmt.Errorf("debug: watchpoint slot must be 0-%d", maxWatchpoints-1)
 	}
-	if !wpSlots[slot] {
+	if !s.wpSlots[slot] {
 		return fmt.Errorf("debug: watchpoint slot %d is not in use", slot)
 	}
 
@@ -126,13 +123,13 @@ func (s *Session) ClearWatchpoint(slot int) error {
 	if err := s.setHWBreakState(state); err != nil {
 		return err
 	}
-	wpSlots[slot] = false
+	s.wpSlots[slot] = false
 	return nil
 }
 
 func (s *Session) ClearAllWatchpoints() error {
 	for slot := 0; slot < maxWatchpoints; slot++ {
-		if wpSlots[slot] {
+		if s.wpSlots[slot] {
 			if err := s.ClearWatchpoint(slot); err != nil {
 				return err
 			}

debug/watchpoint_linux_loong64.go

@@ -21,14 +21,11 @@ const (
 	WatchRead  WatchpointType = 3
 )
 
-// wpSlots tracks watchpoint slot occupancy.
-var wpSlots [4]bool
-
 const maxWatchpoints = 4
 
 func (s *Session) FindFreeWatchpointSlot() int {
 	for i := range maxWatchpoints {
-		if !wpSlots[i] {
+		if !s.wpSlots[i] {
 			return i
 		}
 	}
@@ -39,7 +36,7 @@ func (s *Session) IsWatchpointSlotUsed(slot int) bool {
 	if slot < 0 || slot >= maxWatchpoints {
 		return false
 	}
-	return wpSlots[slot]
+	return s.wpSlots[slot]
 }
 
 // SetWatchpoint installs a hardware watchpoint.
@@ -47,7 +44,7 @@ func (s *Session) SetWatchpoint(slot int, addr uint64, typ WatchpointType, size
 	if slot < 0 || slot >= maxWatchpoints {
 		return fmt.Errorf("debug: watchpoint slot must be 0-%d", maxWatchpoints-1)
 	}
-	if wpSlots[slot] {
+	if s.wpSlots[slot] {
 		return fmt.Errorf("debug: watchpoint slot %d already in use", slot)
 	}
 	if size != 1 && size != 2 && size != 4 && size != 8 {
@@ -85,7 +82,7 @@ func (s *Session) SetWatchpoint(slot int, addr uint64, typ WatchpointType, size
 		return fmt.Errorf("debug: set watchpoint control: %w", err)
 	}
 
-	wpSlots[slot] = true
+	s.wpSlots[slot] = true
 	return nil
 }
 
@@ -93,20 +90,20 @@ func (s *Session) ClearWatchpoint(slot int) error {
 	if slot < 0 || slot >= maxWatchpoints {
 		return fmt.Errorf("debug: watchpoint slot must be 0-%d", maxWatchpoints-1)
 	}
-	if !wpSlots[slot] {
+	if !s.wpSlots[slot] {
 		return fmt.Errorf("debug: watchpoint slot %d is not in use", slot)
 	}
 
 	if err := ptracePokeUser(s.pid, uintptr(0x1001+slot*8), 0); err != nil {
 		return err
 	}
-	wpSlots[slot] = false
+	s.wpSlots[slot] = false
 	return nil
 }
 
 func (s *Session) ClearAllWatchpoints() error {
 	for slot := 0; slot < maxWatchpoints; slot++ {
-		if wpSlots[slot] {
+		if s.wpSlots[slot] {
 			if err := s.ClearWatchpoint(slot); err != nil {
 				return err
 			}

debug/watchpoint_linux_riscv64.go

@@ -21,14 +21,11 @@ const (
 	WatchRead  WatchpointType = 3
 )
 
-// wpSlots tracks watchpoint slot occupancy.
-var wpSlots [4]bool
-
 const maxWatchpoints = 4
 
 func (s *Session) FindFreeWatchpointSlot() int {
 	for i := range maxWatchpoints {
-		if !wpSlots[i] {
+		if !s.wpSlots[i] {
 			return i
 		}
 	}
@@ -39,7 +36,7 @@ func (s *Session) IsWatchpointSlotUsed(slot int) bool {
 	if slot < 0 || slot >= maxWatchpoints {
 		return false
 	}
-	return wpSlots[slot]
+	return s.wpSlots[slot]
 }
 
 // SetWatchpoint installs a hardware watchpoint.
@@ -47,7 +44,7 @@ func (s *Session) SetWatchpoint(slot int, addr uint64, typ WatchpointType, size
 	if slot < 0 || slot >= maxWatchpoints {
 		return fmt.Errorf("debug: watchpoint slot must be 0-%d", maxWatchpoints-1)
 	}
-	if wpSlots[slot] {
+	if s.wpSlots[slot] {
 		return fmt.Errorf("debug: watchpoint slot %d already in use", slot)
 	}
 	if size != 1 && size != 2 && size != 4 && size != 8 {
@@ -87,7 +84,7 @@ func (s *Session) SetWatchpoint(slot int, addr uint64, typ WatchpointType, size
 		return fmt.Errorf("debug: set watchpoint control: %w", err)
 	}
 
-	wpSlots[slot] = true
+	s.wpSlots[slot] = true
 	return nil
 }
 
@@ -95,7 +92,7 @@ func (s *Session) ClearWatchpoint(slot int) error {
 	if slot < 0 || slot >= maxWatchpoints {
 		return fmt.Errorf("debug: watchpoint slot must be 0-%d", maxWatchpoints-1)
 	}
-	if !wpSlots[slot] {
+	if !s.wpSlots[slot] {
 		return fmt.Errorf("debug: watchpoint slot %d is not in use", slot)
 	}
 
@@ -103,13 +100,13 @@ func (s *Session) ClearWatchpoint(slot int) error {
 	if err := ptracePokeUser(s.pid, uintptr(0x1001+slot*8), 0); err != nil {
 		return err
 	}
-	wpSlots[slot] = false
+	s.wpSlots[slot] = false
 	return nil
 }
 
 func (s *Session) ClearAllWatchpoints() error {
 	for slot := 0; slot < maxWatchpoints; slot++ {
-		if wpSlots[slot] {
+		if s.wpSlots[slot] {
 			if err := s.ClearWatchpoint(slot); err != nil {
 				return err
 			}

disasm/disasm.go

@@ -0,0 +1,95 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Package disasm decodes machine code back to instruction text for the four
+// architectures gasm assembles.  It is a thin, platform-independent wrapper
+// over golang.org/x/arch and backs both the `gasm dis` command and the live
+// debugger views.
+package disasm
+
+import (
+	"fmt"
+
+	"golang.org/x/arch/arm64/arm64asm"
+	"golang.org/x/arch/loong64/loong64asm"
+	"golang.org/x/arch/riscv64/riscv64asm"
+	"golang.org/x/arch/x86/x86asm"
+
+	"sourcedock.dev/petrbalvin/gasm-devkit/arch"
+)
+
+// Instruction is one decoded instruction: its text form, its length in bytes
+// and the address it was decoded at.
+type Instruction struct {
+	Addr uint64
+	Text string
+	Len  int
+}
+
+// Decode decodes the instruction at the start of code, located at addr.
+// code needs to hold at least the one instruction being decoded (amd64 may
+// consume up to 15 bytes).  Undecodable bytes yield the placeholder text "???"
+// and a length of one word (four bytes, one on amd64) so that a listing can
+// keep making progress, mirroring the debugger's behaviour.
+func Decode(a arch.Arch, code []byte, addr uint64) (Instruction, error) {
+	if len(code) == 0 {
+		return Instruction{}, fmt.Errorf("disasm: empty input")
+	}
+	switch a {
+	case arch.ARM64:
+		if len(code) < 4 {
+			return Instruction{}, fmt.Errorf("disasm: need 4 bytes, have %d", len(code))
+		}
+		inst, err := arm64asm.Decode(code)
+		if err != nil {
+			return Instruction{Addr: addr, Text: "???", Len: 4}, nil
+		}
+		return Instruction{Addr: addr, Text: arm64asm.GoSyntax(inst, addr, nil, nil), Len: 4}, nil
+
+	case arch.RISCV:
+		// The compressed extensions are decoded transparently; a 16-bit
+		// instruction only needs its two bytes.
+		inst, err := riscv64asm.Decode(code)
+		if err != nil {
+			return Instruction{Addr: addr, Text: "???", Len: 2}, nil
+		}
+		return Instruction{Addr: addr, Text: riscv64asm.GoSyntax(inst, addr, nil, nil), Len: inst.Len}, nil
+
+	case arch.LOONG64:
+		if len(code) < 4 {
+			return Instruction{}, fmt.Errorf("disasm: need 4 bytes, have %d", len(code))
+		}
+		inst, err := loong64asm.Decode(code)
+		if err != nil {
+			return Instruction{Addr: addr, Text: "???", Len: 4}, nil
+		}
+		return Instruction{Addr: addr, Text: loong64asm.GoSyntax(inst, addr, nil), Len: 4}, nil
+
+	default: // amd64
+		inst, err := x86asm.Decode(code, 64)
+		if err != nil {
+			return Instruction{Addr: addr, Text: "???", Len: 1}, nil
+		}
+		return Instruction{Addr: addr, Text: x86asm.IntelSyntax(inst, addr, nil), Len: inst.Len}, nil
+	}
+}
+
+// Block decodes up to max instructions from code starting at addr and returns
+// them in order.  Decoding stops at the end of code or once an instruction
+// would run past it.
+func Block(a arch.Arch, code []byte, addr uint64, max int) []Instruction {
+	var out []Instruction
+	pc := 0
+	for len(out) < max && pc < len(code) {
+		ins, err := Decode(a, code[pc:], addr+uint64(pc))
+		if err != nil {
+			break
+		}
+		if ins.Len <= 0 || pc+ins.Len > len(code) {
+			break
+		}
+		out = append(out, ins)
+		pc += ins.Len
+	}
+	return out
+}

disasm/disasm_test.go

@@ -0,0 +1,141 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+package disasm
+
+import (
+	"strings"
+	"testing"
+
+	"sourcedock.dev/petrbalvin/gasm-devkit/arch"
+	"sourcedock.dev/petrbalvin/gasm-devkit/asm"
+	"sourcedock.dev/petrbalvin/gasm-devkit/ast"
+	"sourcedock.dev/petrbalvin/gasm-devkit/parser"
+)
+
+func TestDecodeKnownBytes(t *testing.T) {
+	for _, tt := range []struct {
+		a    arch.Arch
+		code []byte
+		text string
+		want int
+	}{
+		{arch.AMD64, []byte{0x55}, "push rbp", 1},
+		{arch.AMD64, []byte{0x48, 0x89, 0xE5}, "mov rbp, rsp", 3},
+		{arch.ARM64, []byte{0xc0, 0x03, 0x5f, 0xd6}, "RET", 4},
+		{arch.RISCV, []byte{0x67, 0x80, 0x00, 0x00}, "RET", 4},
+		{arch.LOONG64, []byte{0x20, 0x00, 0x00, 0x4c}, "RET", 4},
+	} {
+		ins, err := Decode(tt.a, tt.code, 0)
+		if err != nil {
+			t.Errorf("%s: %v", tt.a, err)
+			continue
+		}
+		if ins.Text != tt.text || ins.Len != tt.want {
+			t.Errorf("%s: % x decoded to %q (%d bytes), want %q (%d)",
+				tt.a, tt.code, ins.Text, ins.Len, tt.text, tt.want)
+		}
+	}
+}
+
+func TestDecodeUndecodable(t *testing.T) {
+	// Zero words do not encode a usable instruction on arm64 and loong64; the
+	// placeholder keeps a listing going.  RISC-V is the exception: an all-zero
+	// word is the defined UNIMP instruction.
+	for _, a := range []arch.Arch{arch.ARM64, arch.LOONG64} {
+		ins, err := Decode(a, []byte{0, 0, 0, 0}, 0)
+		if err != nil {
+			t.Fatalf("%s: %v", a, err)
+		}
+		if ins.Text != "???" {
+			t.Errorf("%s: text = %q, want ???", a, ins.Text)
+		}
+	}
+	// The compressed quadrant claims the zero halfword first, so the zero
+	// word decodes as the 2-byte compressed UNIMP.
+	if ins, err := Decode(arch.RISCV, []byte{0, 0, 0, 0}, 0); err != nil || ins.Text != "UNIMP" || ins.Len != 2 {
+		t.Errorf("riscv zero word: %q len %d err %v, want UNIMP with 2 bytes", ins.Text, ins.Len, err)
+	}
+	if _, err := Decode(arch.ARM64, []byte{0, 0}, 0); err == nil {
+		t.Error("short input: expected an error")
+	}
+	if _, err := Decode(arch.AMD64, nil, 0); err == nil {
+		t.Error("empty input: expected an error")
+	}
+}
+
+// TestBlockRoundTrip assembles a small kernel with the gasm encoder for every
+// architecture and disassembles it back: the listing must cover the whole
+// function and end in RET.
+func TestBlockRoundTrip(t *testing.T) {
+	for _, tt := range []struct {
+		a    arch.Arch
+		name string
+	}{
+		{arch.AMD64, "k_amd64.s"},
+		{arch.ARM64, "k_arm64.s"},
+		{arch.RISCV, "k_riscv64.s"},
+		{arch.LOONG64, "k_loong64.s"},
+	} {
+		src := "TEXT \u00b7k(SB), NOSPLIT, $0\n\tMOVQ AX, CX\n\tRET\n"
+		if tt.a != arch.AMD64 {
+			src = "TEXT \u00b7k(SB), NOSPLIT, $0\n\tRET\n"
+		}
+		f, errs := parser.Parse(tt.name, src)
+		if len(errs) > 0 {
+			t.Fatalf("%s: parse: %v", tt.a, errs)
+		}
+		img, err := assemble(t, tt.a, f)
+		if err != nil {
+			t.Fatalf("%s: assemble: %v", tt.a, err)
+		}
+		fn := img.Funcs[0]
+		code := img.Code[fn.Offset : fn.Offset+fn.Size]
+
+		ins := Block(tt.a, code, 0, 100)
+		if len(ins) == 0 {
+			t.Fatalf("%s: empty listing", tt.a)
+		}
+		consumed := 0
+		for _, in := range ins {
+			if in.Text == "" || in.Text == "???" {
+				t.Errorf("%s: undecoded instruction at %#x: %q", tt.a, in.Addr, in.Text)
+			}
+			consumed += in.Len
+		}
+		if consumed != len(code) {
+			t.Errorf("%s: listing consumed %d of %d bytes", tt.a, consumed, len(code))
+		}
+		if last := ins[len(ins)-1]; !strings.Contains(strings.ToLower(last.Text), "ret") {
+			t.Errorf("%s: last instruction = %q, want RET", tt.a, last.Text)
+		}
+	}
+}
+
+func TestBlockLimits(t *testing.T) {
+	code := []byte{0x55, 0x55, 0x55, 0x55, 0x55}
+	if got := Block(arch.AMD64, code, 0, 3); len(got) != 3 {
+		t.Errorf("max=3 produced %d instructions, want 3", len(got))
+	}
+	if got := Block(arch.AMD64, code, 0, 100); len(got) != 5 {
+		t.Errorf("code end produced %d instructions, want 5", len(got))
+	}
+	if got := Block(arch.AMD64, nil, 0, 3); len(got) != 0 {
+		t.Errorf("empty code produced %d instructions, want 0", len(got))
+	}
+}
+
+// assemble assembles the parsed file with the encoder for a.
+func assemble(t *testing.T, a arch.Arch, f *ast.File) (*asm.Image, error) {
+	t.Helper()
+	switch a {
+	case arch.ARM64:
+		return asm.AssembleFileARM64(f)
+	case arch.RISCV:
+		return asm.AssembleFileRISCV(f)
+	case arch.LOONG64:
+		return asm.AssembleFileLOONG64(f)
+	default:
+		return asm.AssembleFile(f)
+	}
+}

docs/ARCHITECTURE.md

@@ -4,7 +4,9 @@ How gasm-devkit is put together and why.
 
 Repository: [sourcedock.dev/petrbalvin/gasm-devkit](https://sourcedock.dev/petrbalvin/gasm-devkit)
 
-## Design goals
+## Overview
+
+Three design goals shape everything below.
 
 1. **A real AST, not a grammar hack.**  The linter, analyser, assembler and
    language server all need to *reason* about assembly, not just colour it.
@@ -20,10 +22,10 @@ Repository: [sourcedock.dev/petrbalvin/gasm-devkit](https://sourcedock.dev/petrb
    through two vendor-neutral interfaces: a CLI and an LSP server.  No editor
    owns the toolkit; the toolkit is offered to editors on standard terms.
 
-## Pipeline
+The components, and how data moves between them:
 
 ```mermaid
-graph TD
+flowchart TD
     SRC["source .s"] --> LEX["lexer<br/>token stream"]
     LEX --> PAR["parser<br/>AST + diagnostics"]
     LEX --> FMT["format<br/>re-space tokens"]
@@ -42,9 +44,34 @@ graph TD
 
 The lexer is the shared foundation: the parser builds the AST from it, the
 formatter re-spaces its tokens directly, and the language server uses it for
-semantic highlighting.
+semantic highlighting.  The phases follow a dependency chain: Phase 1 (static
+analysis) builds only on the AST, Phase 2 (the standalone assembler) emits
+object code, and Phases 3 (dynamic analysis) and 4 (the debugger) both consume
+the execution substrate that the assembler provides.
 
-## Components
+## Packages
+
+| Package | Responsibility |
+|---|---|
+| `token` | token kinds and positions |
+| `lexer` | hand-written scanner; permissive, and it never panics |
+| `ast` | the typed syntax tree: declarations, lines, operands |
+| `parser` | line-oriented parser producing the AST and its diagnostics |
+| `arch` | register and instruction tables for the four architectures |
+| `lint` | static checks over the AST |
+| `format` | canonical formatter over the token stream |
+| `lsp` | the language server |
+| `asm` | standalone assembler: encoders, image layout, object emitters |
+| `verify` | JIT execution, ABI checks, differential fuzzing |
+| `debug` | interactive ptrace debugger |
+| `cmd/gasm` | the CLI |
+| `_gen` | rebuilds the `arch` tables from the Go toolchain source |
+
+The boundaries matter as much as the responsibilities: `ast` records syntax
+only, and whether a name is a register or a label is left to `arch`, so the
+parser stays architecture-agnostic.  `asm` and `verify` are the only packages
+that touch machine code and executable memory, and `cmd/gasm` owns no logic
+beyond flags and output.
 
 ### `token` and `lexer`
 
@@ -134,7 +161,8 @@ Two deeper analyses sit on top of the AST:
 - **`unreachable-code`.**  Code after a `RET` and before the next label is
   dead.  The check is suppressed for any function whose reachability cannot be
   decided statically: those using PC-relative jumps (`JMP 2(PC)`),
-  register-indirect branches (`JALR`/`JR`/`JIRL`/`BR`/`BLR`), or living in a
+  register-indirect branches (`JALR`/`JR`/`JIRL`/`BR`/`BLR`, or a `JMP`/`CALL`
+  through a register or memory operand), or living in a
   file with `#ifdef` conditionals.  `UNDEF` is deliberately not a terminator:
   code after it is occasionally intentional metadata.
 - **`register-clobber` (register liveness).**  The linter builds the function's
@@ -206,7 +234,7 @@ The standalone assembler (Phase 2).  Its core is an amd64 instruction encoder:
 a REX/ModR-M/SIB/displacement/immediate engine plus the scalar instruction set,
 with the Plan 9 operand order (source first) mapped onto the x86 encoding.
 Every encoding is validated by decoding it again with `golang.org/x/arch`, the
-one module dependency, used in tests only and never linked into the binary.
+one module dependency, which also backs the `gasm dis` listings.
 
 A **RISC-V encoder** (Phase 5, RV64IMAFDC + RVC compression) encodes the full
 integer, atomic, float/double, FMA and CSR instruction sets with the MOV
@@ -237,6 +265,18 @@ STP+SUB for large frames) and SB/global symbol references (ADRP+ADD pairs with
 R_ADDRARM64 relocations).  Like the other encoders it is validated
 byte-for-byte against `GOARCH=arm64 go tool asm`.
 
+On top of the per-architecture encoders, every framed function carries the
+**stack-split guard**: the prologue check against `g.stackguard0` (small,
+medium and large frame classes, the medium and large classes materialising
+their offset through the architecture's temporary register and the large
+class adding the SP-underflow branch) and the trailing morestack block
+(save the link register, `CALL runtime.morestack_noctxt`, jump back to the
+function entry).  The auto-NOSPLIT rule, the frame classes, the large-frame
+prologue and epilogue forms and the tail calls match the toolchain's
+`stacksplit` and `preprocess` output byte for byte; a parity suite
+assembles kernel files with gasm and the installed `go tool asm` and diffs
+the bytes on all four architectures.
+
 On top of the encoder, `Assemble` walks a parsed `TEXT` body, converts each
 operand to an encoder operand, and lays the instructions out so local labels
 resolve to relative jump offsets: jumps start in the short (rel8) form and
@@ -371,8 +411,8 @@ the Go ABI fixes across calls (amd64 `BP`/`R14`, arm64 `R29`/`R28`, riscv64
 raw return trampoline `leaveJITCheckedRaw` verifies them, restoring the
 saved registers before Go code resumes.  riscv64 is validated end to
 end under qemu-user emulation; arm64 shares the same stack convention and
-fix; loong64 stays ground-truth-only until hardware validation (see
+fix; loong64 stays ground-truth-only until hardware validation.
-docs/DECISIONS.md).  `gasm verify` runs the JIT checks when the host
+`gasm verify` runs the JIT checks when the host
 matches the kernel's architecture and the toolchain comparisons
 elsewhere.
 
@@ -424,14 +464,72 @@ watchdog is armed before the ptrace attach, so a sandboxed debuggee cannot
 block it), and `--cover` runs to completion with a breakpoint on every
 label and reports which blocks executed.
 
-## Extension points
+### Extending the toolkit
 
 - **New architecture:** add an entry to the generator in `_gen`, run
   `just gen`, and add a `buildXXX()` register file plus a case in `ForArch`.
 - **New lint rule:** add a function in `lint` and a rule-code constant.
 - **New LSP feature:** add a method case in `dispatch` and a handler.
 
-The phases follow a dependency chain.  Phase 1 (static analysis) builds only on
+## Data flow
-the AST; Phase 2 (the standalone assembler) emits object code; Phases 3
+
-(dynamic analysis) and 4 (the debugger) both consume the execution substrate
+The main operation, assembling one file:
-that the assembler provides.
+
+```mermaid
+sequenceDiagram
+    participant User
+    participant CLI as gasm CLI
+    participant Parser as parser
+    participant Asm as asm
+    participant Go as go toolchain
+    User->>CLI: gasm asm --format goobj -p pkg -o k.o k_amd64.s
+    CLI->>Parser: Parse(path, src)
+    Parser-->>CLI: AST, diagnostics
+    CLI->>Asm: AssembleFile(AST)
+    Asm->>Asm: encode operands, settle label offsets, lay out data
+    Asm-->>CLI: Image, code and data and relocations
+    CLI->>Asm: GOObject(pkg, path)
+    Asm->>Go: go list -json -export, externals only
+    Go-->>Asm: package and symbol indices
+    Asm-->>CLI: Go object bytes
+    CLI-->>User: wrote N bytes to k.o
+```
+
+Errors are produced where the parse or the encoding fails and become values at
+the CLI boundary: the parser returns a diagnostic list and never aborts a file,
+`AssembleFile` returns an error, and `cmd/gasm` prints what it has to stderr
+and returns a non-zero exit code.  The formatter and the linter take the same
+AST by a different route: `gasm fmt` re-spaces the token stream and `gasm lint`
+walks the parsed file, so neither depends on an encoding.
+
+## State and lifetime
+
+- The analysis packages (`lexer`, `parser`, `format`, `lint`, `arch`) hold only
+  read-only lookup tables and no mutable state: every call allocates its own
+  tokens and AST, and any number of goroutines may read the `arch` tables.
+- A `verify.Kernel` owns one executable mapping, which `Close` releases.  The
+  JIT trampolines keep the Go stack pointer and the checked-call sentinels in
+  package globals, so a call is a process-wide, one-at-a-time operation.  The
+  `gasm verify` sweeps therefore run each function in a child process, which
+  contains a crash and keeps the globals unshared.
+- `lsp.Server` is long-lived: it runs a single read and dispatch loop over the
+  stream and touches its document store only from that loop, so one server
+  serves one connection.
+- A `debug.Session` owns a traced child process and pins its goroutine to the
+  forking OS thread, because ptrace requests must stay on that thread.
+
+## Dependencies
+
+- **`golang.org/x/arch`** (v0.30.0) is the one module dependency: it is the
+  disassembler backend (`gasm dis` and the debugger's listings) and the source
+  of the register metadata the encoder consults (`asm/reg.go`, `asm/vex.go`).
+  The tests additionally decode through it to validate the encodings.
+- **The Go toolchain**, as an oracle and never as a library: `go tool asm`
+  supplies the object preamble and the ground truth for `gasm verify
+  --ground-truth`, `go list -json -export` locates the archives of the packages
+  a GOOBJ object references, and `_gen` parses
+  `$GOROOT/src/cmd/internal/obj/<arch>/anames.go` to rebuild the tables.
+- **Linux process interfaces** for the dynamic work: `mmap` and `mprotect` for
+  the JIT mapping, ptrace with `/proc/pid/mem` for the debugger.  That is why
+  `verify` runs a JIT check only when the host architecture matches the
+  kernel's, and why `debug` is Linux-only.

docs/CLI.md

@@ -1,198 +1,472 @@
-# CLI Reference
+# Command line
 
-Repository: [sourcedock.dev/petrbalvin/gasm-devkit](https://sourcedock.dev/petrbalvin/gasm-devkit)
+The reference below is taken from the program's own `--help`. If the two disagree, the
+program is right and this file is a defect.
 
-`gasm` is a single binary with subcommands. Run `gasm --help` for an
+The same reference is installed as man pages: `just install-man` puts gasm(1) and one
-overview, or `gasm <command> -h` for a command's usage and flags.
+page per command into ~/.local/share/man (`MANDIR` overrides), and a test compares each
+page against the binary so the two cannot drift apart.
 
-## Global Flags
+## Synopsis
 
-| Flag | Description |
+```sh
-|------|-------------|
+gasm [global flags] <command> [command flags] [arguments]
-| `-h`, `--help` | Show help |
+```
-| `-V`, `--version` | Print the version |
 
-## `gasm tokens <file>`
+## Commands
 
-Print the lexical token stream of FILE: position, token kind, and text,
+| Command | Purpose |
-one token per line. FILE may be `-` to read standard input.
+|---|---|
+| `tokens` | print the lexical token stream |
+| `parse` | parse a file and report syntax errors |
+| `fmt` | canonicalise the formatting of `.s` files |
+| `lint` | run the static checks |
+| `asm` | assemble `.s` files to machine code |
+| `dis` | disassemble machine code or an assembled file |
+| `verify` | JIT-assemble and run the dynamic checks |
+| `debug` | interactive source-level debugger |
+| `diff` | compare the machine code of two `.s` files |
+| `profile` | show the basic-block structure of the functions |
+| `audit-instructions` | diff the encoder against the toolchain's name table |
+| `scaffold` | generate a differential test skeleton for a kernel |
+| `lsp` | run the language server over stdio |
+| `version` | print the version |
 
-## `gasm parse <file>`
+## tokens
 
-Parse FILE and report syntax errors on stderr. On success, prints how
+```text
-many declarations and TEXT functions the file contains.
+Usage: gasm tokens <file>
+```
 
-## `gasm fmt [-w] [path...]`
+Print the lexical token stream of FILE: position, token kind and text, one
+token per line. FILE may be `-` to read standard input.
 
-Canonicalise the formatting of Plan 9 assembly sources: indentation,
+```sh
-operand spacing, per-function mnemonic alignment, and blank-line layout.
+gasm tokens hello_amd64.s
+```
 
-| Flag | Description |
+```text
-|------|-------------|
+1:1	#	"#"
-| `-w` | Write result to the source file (default: print to stdout) |
+1:2	IDENT	"include"
+1:10	STRING	"\"textflag.h\""
+```
 
-With no arguments, or with a directory argument, every `.s` file below
+## parse
-it is reformatted in place and the names of changed files are listed
-(`go fmt` style). `.` and `_` directories are skipped.
 
-## `gasm lint <file...>`
+```text
+Usage: gasm parse <file>
+```
 
-Run static checks and print diagnostics as
+Parse FILE and report syntax errors on stderr. On success, print how many
-`file:line:col: severity: message [code]`. Exit status is non-zero when
+declarations and TEXT functions the file contains.
-an error-severity diagnostic is found.
 
-| Flag | Description |
+```sh
-|------|-------------|
+gasm parse hello_amd64.s
-| `-disable` | Comma-separated rule codes to disable |
+```
+
+```text
+hello_amd64.s: OK, 2 declarations, 1 functions
+```
+
+## fmt
+
+```text
+Usage: gasm fmt [-w|-l|-d] [path...]
+```
+
+| Flag | Default | Effect |
+|---|---|---|
+| `-w` | off | write the result back to the source file |
+| `-l` | off | list the files whose formatting differs; write nothing |
+| `-d` | off | print a unified diff of the canonical formatting instead |
+
+`-l` and `-d` are mutually exclusive. With no arguments, or with a directory
+argument, every `.s` file below it is reformatted in place and the names of the
+changed files are listed, the way `go fmt` does; `.` and `_` directories are
+skipped. Explicit file arguments print to stdout unless `-w` is given.
+
+```sh
+gasm fmt -l kernel_amd64.s
+```
+
+Empty output means every file is formatted, which is the shape a CI check
+wants; `-d` shows what would change:
+
+```sh
+gasm fmt -d ugly_amd64.s
+```
+
+```text
+--- ugly_amd64.s
++++ ugly_amd64.s
+@@ -2,8 +2,8 @@
+
+ // func add(a, b int) int
+ TEXT ·add(SB), NOSPLIT, $0-24
+-        MOVQ a+0(FP), AX
+-        ADDQ b+8(FP), AX
++	MOVQ a+0(FP), AX
++	ADDQ b+8(FP), AX
+```
+
+## lint
+
+```text
+Usage: gasm lint <file...>
+```
+
+| Flag | Default | Effect |
+|---|---|---|
+| `-disable` | empty | comma-separated rule codes to disable |
+
+Diagnostics are printed as `file:line:col: severity: message [code]`. The exit
+status is non-zero when an error-severity diagnostic is found; warnings (the
+register-clobber audit, for example) do not affect it.
 
 Rules: `unknown-instruction`, `operand-count`, `undefined-label`,
 `duplicate-label`, `missing-ret`, `missing-textflag-include`,
 `abi-argsize`, `unreachable-code`, `register-clobber`,
 `funcdata-pcdata`, `unused-label`, `invalid-textflag`,
 `stack-imbalance`, `register-width-mismatch`, `abi0-register-args`,
-`nonportable-register-name` and `unencodable-instruction`.
+`nonportable-register-name`, `unencodable-instruction` and
+`reserved-register-write`.
 
-## `gasm asm [--format raw|elf|goobj] [-p pkg] [-o out] <file>`
+```sh
+gasm lint kernel_amd64.s
+```
 
-Assemble FILE to machine code (amd64, arm64, riscv64, loong64).
+## asm
 
-| Flag | Description |
+```text
-|------|-------------|
+Usage: gasm asm [--format raw|elf|goobj] [-p pkg] [-GOARCH arch] [-o out] <file>
-| `--format` | Output format: `raw` (default), `elf`, `goobj` |
+```
-| `-p` | Package path (required for `--format goobj`) |
-| `-o` | Write output to file (default: hex dump to stdout) |
 
-## `gasm verify [flags] <file.s>`
+| Flag | Default | Effect |
+|---|---|---|
+| `-format` | `raw` | output format: `raw` (concatenated image), `elf` or `goobj` (Go object) |
+| `-p` | empty | package path for `--format goobj`, qualifying the exported symbols |
+| `-GOARCH` | empty | target architecture: `amd64`, `arm64`, `riscv64` or `loong64`; overrides the file-name suffix |
+| `-o` | empty | write the output to this file instead of a hex dump on stdout |
 
-Assemble FILE, map it into executable memory, and run dynamic checks.
+Supported architectures: amd64 (VEX/AVX2 and EVEX/AVX-512 included), arm64,
+riscv64 (RV64IMAFDC and RVC) and loong64, taken from the file's `_arch.s`
+suffix or from `-GOARCH`, which is how files whose names carry no
+recognisable suffix (most of GOROOT's, for example `cpu_x86.s`) are
+assembled. `raw` concatenates the functions and the data section into one
+self-consistent image; `elf` emits a relocatable object that links with the
+system toolchain; `goobj` emits the Go toolchain's own object format, which
+`cmd/link` consumes directly.
 
-| Flag | Description |
+```sh
-|------|-------------|
+gasm asm hello_amd64.s
-| `--ground-truth` | Compare machine code byte-for-byte against `go tool asm` |
+```
-| `--fuzz` | Differential fuzz: JIT both gasm and go-tool-asm, compare outputs |
-| `-n` | Fuzz iterations per function (default: 1000) |
-| `--abi` | Run ABI-checking calls (sentinel registers + red zone) |
-| `--abi-n` | Number of ABI check iterations with varied inputs (default: 100) |
-| `--profile` | List basic-block structure per function |
-| `--smoke` | Call each NOSPLIT function with zeroed args |
-| `--call <func>` | Invoke a single function with `--buf` instead of the sweeps |
-| `--buf <spec>` | Buffer spec for `--call`: `name:size:pattern[,name:size:pattern]` |
-| `--args <spec>` | Scalar args for `--call`: `name=value[,name=value]` (decimal or `0x` hex) |
-| `--repeat <n>` | Number of times to repeat a `--call` invocation (default: 1) |
-| `--save-corpus <dir>` | With `--fuzz`: write each failing input to DIR as replayable JSON |
-| `--replay <dir>` | Re-run saved corpus entries (JSON in DIR), one child process per entry |
 
-The `--fuzz` mode runs each function in a subprocess; a partial function
+```text
-(e.g. a decoder that faults on malformed input) is reported as
+add: 16 bytes
-`CRASH` without killing the parent. Use `--call` with `--buf` to invoke
+  0000: 48 8b 44 24 08 48 03 44 24 10 48 89 44 24 18 c3
-partial functions with valid data instead.
+```
 
-The `--call` mode parses the `// func` signature, allocates the requested
+## dis
-buffers (`zero`, `ones`, `seq`, or a hex blob), builds the ABI0 argument
-block with buffer pointers/lengths/capacities at the matching parameter
-offsets, and prints the arg block before and after the call, showing
-return values and any output written to the buffers.  Scalar parameters
-are supplied with `--args` (decimal, or `0x` hex) at their ABI0 offsets.
 
-The `--save-corpus` mode records the logical arguments (buffer contents and
+```text
-scalars, not raw pointers) of every failing fuzz input as JSON.  `--replay`
+Usage: gasm dis [-a arch] <file>
-rebuilds a live argument block from each entry and calls it in its own child
+```
-process, reporting `OK`, `CRASH (reproduced)` or `FAIL` per entry and
-exiting non-zero when any entry fails.
 
-## `gasm debug [--func <name>] [--buf spec] [--script file] <file.s>`
+| Flag | Default | Effect |
+|---|---|---|
+| `-a` | empty | architecture for raw input without a `_arch.s` name |
 
-Interactive debugger for JIT-assembled functions (amd64, arm64, riscv64,
+With a `.s` file the file is assembled first and the listing follows the real
-loong64). Requires a compiled binary on `$PATH` (not `go run`).
+layout: one block per `TEXT` function, local labels printed at their offsets.
+With any other file, or `-` for standard input, the bytes are disassembled
+linearly and `-a` selects the architecture (amd64, arm64, riscv64 or loong64).
 
-| Flag | Description |
+```sh
-|------|-------------|
+gasm dis hello_amd64.s
-| `--func` | Function to debug (required) |
+```
-| `--buf` | Buffer spec: `name:size:pattern[,name:size:pattern]` |
+
-| `--args <file>` | File containing the ABI0 argument block |
+```text
-| `--script <file>` | Run REPL commands from a file (one per line) and exit; `-` reads stdin |
+add: 16 bytes
-| `--timeout <dur>` | Kill the debuggee after this duration (e.g. `30s`); for headless `--script` runs |
+  0000: 48 8b 44 24 08   mov rax, qword ptr [rsp+0x8]
-| `--cover` | Run to completion with a breakpoint on every instruction; report which executed, how often, and which labels were reached |
+  0005: 48 03 44 24 10   add rax, qword ptr [rsp+0x10]
+  000a: 48 89 44 24 18   mov qword ptr [rsp+0x18], rax
+  000f: c3               ret
+```
+
+## verify
+
+```text
+Usage: gasm verify [-smoke] [-abi] [-fuzz] [-ground-truth] [-profile] [-call] <file.s>
+```
+
+| Flag | Default | Effect |
+|---|---|---|
+| `--ground-truth` | off | compare the machine code byte-for-byte against `go tool asm` |
+| `--fuzz` | off | differential fuzz against the `go tool asm` build |
+| `-n` | 1000 | fuzz iterations per function |
+| `--abi` | off | ABI-checking calls: sentinel registers and a red-zone canary |
+| `--abi-n` | 100 | ABI check iterations with varied inputs |
+| `--profile` | off | list the basic-block structure per function |
+| `--smoke` | off | call each NOSPLIT function with zeroed arguments |
+| `--call` | empty | invoke a single function with `--buf` instead of the sweeps |
+| `--buf` | empty | buffer spec for `--call`: `name:size:pattern[,name:size:pattern]` |
+| `--args` | empty | scalar args for `--call`: `name=value[,name=value]` (decimal or `0x` hex) |
+| `--repeat` | 1 | number of times to repeat a `--call` invocation |
+| `--save-corpus` | empty | with `--fuzz`: write each failing input to this directory as replayable JSON |
+| `--replay` | empty | re-run saved corpus entries, one child process per entry |
+
+The JIT checks run when the host matches the file's architecture; the
+toolchain comparison works everywhere. `--fuzz`, `--smoke` and `--abi` run each
+function in its own child process, so a partial function that faults on random
+input is reported as `CRASH` instead of ending the sweep; `--call` with `--buf`
+invokes such a function with valid data. loong64 stays on the ground-truth path
+until hardware validation.
+
+```sh
+gasm verify --ground-truth hello_amd64.s
+```
+
+```text
+hello_amd64.s: 1 functions JIT-loaded
+  add: MATCH (16 bytes)
+ground truth: 1/1 functions byte-identical
+  add: 16 bytes, args=24, frame=0 NOSPLIT
+```
+
+```sh
+gasm verify --call add --args a=2,b=3 hello_amd64.s
+```
+
+```text
+add: 16 bytes, args=24
+  signature: func add(a int, b int) int
+  scalars:
+    a = 2
+    b = 3
+  args before: 02 00 00 00 00 00 00 00 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 (24 bytes)
+  args after:  02 00 00 00 00 00 00 00 03 00 00 00 00 00 00 00 05 00 00 00 00 00 00 00 (24 bytes)
+  call 1: OK
+```
+
+## debug
+
+```text
+Usage: gasm debug <file.s> --func <name>
+```
+
+| Flag | Default | Effect |
+|---|---|---|
+| `-func` | empty | the function to debug, required |
+| `-buf` | empty | buffer spec: `name:size:pattern[,name:size:pattern]` (zero, ones, seq or hex) |
+| `-args` | empty | file containing the ABI0 argument block |
+| `-script` | empty | run REPL commands from a file, one per line, and exit; `-` reads stdin |
+| `-timeout` | 0 | kill the debuggee after this duration, for headless `-script` runs |
+| `-cover` | off | run to completion with a breakpoint on every instruction and report which executed |
+
+The debugger spawns the debuggee from the `gasm` binary on `$PATH`, so install
+it first with `just install`; `go run` does not work for the traced child.
+Requires Linux (ptrace) and all four architectures are supported.
 
 REPL commands:
 
-| Command | Description |
+| Command | Effect |
-|---------|-------------|
+|---|---|
-| `break <label\|addr> [if <reg> <op> <val>]` | Set a breakpoint, optionally conditional |
+| `break <label\|addr> [if <reg> <op> <val>]` | set a breakpoint, optionally conditional |
-| `delete <label\|addr>` | Remove a breakpoint |
+| `delete <label\|addr>` | remove a breakpoint |
-| `info break` | List all breakpoints |
+| `info break` | list the breakpoints |
-| `step [n]`, `s` | Single-step n instructions |
+| `step [n]`, `s` | single-step n instructions |
-| `next`, `n` | Step over CALL |
+| `next`, `n` | step over a CALL |
-| `finish`, `fin` | Run until the function returns |
+| `finish`, `fin` | run until the function returns |
-| `continue`, `c` | Run until breakpoint, watchpoint or exit |
+| `continue`, `c` | run until a breakpoint, watchpoint or exit |
-| `disas [n]`, `u` | Disassemble n instructions at PC |
+| `disas [n]`, `u` | disassemble n instructions at the PC |
-| `regs` | Print general-purpose + vector/FP registers |
+| `regs` | print the general-purpose and vector/FP registers |
-| `where` | Show source line and nearest label at PC |
+| `where` | show the source line and the nearest label at the PC |
-| `stack` | Show stack near RSP (return address + ABI0 args) |
+| `stack` | show the stack near RSP, the return address and the ABI0 args |
-| `bt`, `backtrace` | Backtrace (current frame + return address) |
+| `bt`, `backtrace` | backtrace: the current frame and the return address |
-| `x [addr] [len]` | Hex-dump memory |
+| `x [addr] [len]` | hex-dump memory |
-| `w <addr> <val...>` | Write bytes to memory |
+| `w <addr> <val...>` | write bytes to memory |
-| `set <reg> <value>` | Set a register |
+| `set <reg> <value>` | set a register |
-| `watch <addr> [r\|w] [size]` | Set a hardware watchpoint (write by default) |
+| `watch <addr> [r\|w] [size]` | set a hardware watchpoint, write by default |
-| `unwatch [<slot>]` | Clear one or all watchpoints |
+| `unwatch [<slot>]` | clear one watchpoint or all of them |
-| `labels`, `l` | List function labels and offsets |
+| `labels`, `l` | list the function's labels and offsets |
-| `help`, `h`, `?` | Show command help |
+| `help`, `h`, `?` | show the command help |
-| `quit`, `q` | Kill the debuggee and exit |
+| `quit`, `q` | kill the debuggee and exit |
 
-## `gasm diff [--map old=new,...] <file1.s> <file2.s>`
+```sh
+gasm debug --func add --cover hello_amd64.s
+```
 
-Compare the machine code produced by assembling two files. Shows which
+## diff
-functions differ and the first few differing bytes. Useful for verifying
-that two implementations produce identical code, or for tracking encoding
-changes between Go assembler versions.
 
-| Flag | Description |
+```text
-|------|-------------|
+Usage: gasm diff [-GOARCH arch] <file1.s> <file2.s>
-| `--map` | Comma-separated `old=new` pairs to match functions with different names |
+```
 
-Without `--map`, functions are paired by exact name. With `--map`, a
+| Flag | Default | Effect |
-function named `old` in the first file is compared against the function
+|---|---|---|
-named `new` in the second file (e.g. `--map wideCopyAVX2=wideCopyAVX512`
+| `-GOARCH` | empty | target architecture for both files, overriding the file-name suffixes |
-pairs AVX2 and AVX-512 variants regardless of suffix).
+| `-map` | empty | comma-separated `old=new` pairs to match functions with different names |
 
-## `gasm profile <file.s>`
+Functions are paired by exact name unless `--map` says otherwise, so
+`--map wideCopyAVX2=wideCopyAVX512` pairs two variants regardless of suffix.
+The exit status is non-zero when anything differs.
 
-Show the basic-block structure of functions in an assembly file. Lists
+```sh
-each function's labels, their offsets, and the block boundaries. This is
+gasm diff hello_amd64.s hello_amd64.s
-the static structure; for runtime execution counts, use `gasm verify
+```
---fuzz` which exercises the code paths.
 
-## `gasm audit-instructions [amd64|arm64|riscv64|loong64]`
+```text
+add: identical (16 bytes)
+all functions identical
+```
 
-Compare the gasm encoder for the given architecture (default amd64)
+## profile
-against the installed `go tool asm` and print the diff: superset
-encodings (gasm-only spellings, shippable via `gasm asm --format goobj`),
-known-but-unencodable names (the encoder backlog) and go-only names
-(feature gaps). The Go side is probed black-box with a battery of operand
-shapes per mnemonic, so the audit tracks whatever toolchain
-`go env GOROOT` provides. On non-amd64 architectures the backlog is an
-over-approximation: a name counts as encodable only when a probe shape
-assembles cleanly, so a name whose real forms the battery misses lands
-in the backlog.
 
-## `gasm scaffold differential <file.s>`
+```text
+Usage: gasm profile <file.s>
+```
 
-Print a differential test skeleton for every `// func` signature in
+Show the basic-block structure of each function: its labels, their offsets and
-FILE. The generated test seeds random states, drives the kernel and a
+the block boundaries. This is the static structure; for runtime execution
-portable reference (`<name>Portable`), and compares outputs
+counts use `gasm debug --cover`, and for input coverage `gasm verify --fuzz`.
-byte-for-byte. Write the reference bodies, place the file in the
-kernel's package, and run it in CI.
 
-## `gasm lsp`
+```sh
+gasm profile hello_amd64.s
+```
 
-Run the language server over standard input/output (JSON-RPC 2.0 with
+```text
-Content-Length framing). Point an LSP-capable editor at the binary and
+add: 16 bytes, args=24, frame=0 NOSPLIT
-associate it with `.s` files. The target architecture is inferred from
+  basic blocks: 1
-the file-name suffix (`_amd64.s`, `_arm64.s`, `_riscv64.s`,
+```
-`_loong64.s`).
 
-Provides: completion, hover, document symbols, push and pull
+## audit-instructions
-diagnostics, semantic tokens, go-to-definition, find references, rename,
+
-document formatting, inlay hints, code actions, signature help, document
+```text
-highlights, workspace symbol search, #include document links, and
+Usage: gasm audit-instructions [--corpus [dir]] [amd64|arm64|riscv64|loong64]
-folding ranges for function bodies.
+```
+
+Compare the gasm encoder for the given architecture (default amd64) against the
+installed `go tool asm` and print the diff: superset encodings (gasm-only
+spellings, shippable via `gasm asm --format goobj`), known-but-unencodable
+names (the encoder backlog) and go-only names (feature gaps). The Go side is
+probed black-box with a battery of operand shapes per mnemonic, so the audit
+tracks whatever toolchain `go env GOROOT` provides. On non-amd64
+architectures the backlog is an over-approximation: a name counts as encodable
+only when a probe shape assembles cleanly, so a name whose real forms the
+battery misses lands in the backlog.
+
+```sh
+gasm audit-instructions amd64
+```
+
+```text
+gasm table (amd64, families excluded): 1542 mnemonics
+gasm encodable: 580   go tool asm recognized: 1542
+shared: 580
+```
+
+With `--corpus` the audit changes shape: it assembles every `.s` file under
+DIR (default `GOROOT/src`) with the gasm encoder only, no toolchain probing.
+A file whose name carries a recognisable `_arch` suffix is attempted for that
+architecture; a file without one is attempted for all four, exactly as a
+`GOARCH` build would compile it. The report gives the headline number (files
+that assemble for every target architecture), the per-architecture pass rates
+and the most common failure reasons with one representative file each, which
+drive the encodability backlog by frequency rather than by table order. A run
+over GOROOT takes under a second.
+
+```sh
+gasm audit-instructions --corpus
+gasm audit-instructions --corpus "$(go env GOROOT)/src/crypto"
+```
+
+```text
+corpus /usr/local/go/src: 627 files (365 generic, attempted for all architectures)
+  assemble for every target architecture: 108 (17.2%)
+  amd64: 77/464 attempted
+    148  instruction not encodable
+         e.g. /usr/local/go/src/cmd/asm/internal/asm/testdata/386enc.s
+...
+```
+
+## scaffold
+
+```text
+Usage: gasm scaffold differential <file.s>
+```
+
+Print a differential test skeleton for every `// func` signature in FILE. The
+generated test seeds random states, drives the kernel and a portable reference
+(`<name>Portable`), and compares the outputs byte-for-byte. Write the reference
+bodies, place the file in the kernel's package, and run it in CI.
+
+```sh
+gasm scaffold differential kernel_amd64.s > kernel_differential_test.go
+```
+
+## lsp
+
+```text
+Usage: gasm lsp
+```
+
+Run the language server over standard input/output, JSON-RPC 2.0 with
+`Content-Length` framing. Point an LSP-capable editor at the binary and
+associate it with `.s` files; the target architecture is inferred from the
+file-name suffix (`_amd64.s`, `_arm64.s`, `_riscv64.s`, `_loong64.s`).
+
+Provides: completion, hover, document symbols, push and pull diagnostics,
+semantic tokens, go-to-definition, find references, rename, document
+formatting, inlay hints, code actions, signature help, document highlights,
+workspace symbol search, #include document links, and folding ranges for
+function bodies. Definition, references and rename work across every open
+document.
+
+## version
+
+```text
+Usage: gasm version
+```
+
+Print the version the toolchain recorded for the build, the same string as
+`gasm --version`: the tag on a tagged checkout, a pseudo-version naming the
+commit below one, with `+dirty` appended on a dirty tree and `(devel)` outside
+version control.
+
+## Global flags
+
+| Flag | Default | Effect |
+|---|---|---|
+| `-h`, `--help` | off | print the usage |
+| `-V`, `--version` | off | print the version |
+
+## Exit codes
+
+| Code | Meaning |
+|---|---|
+| `0` | success |
+| `1` | a failure the program detected: a parse or assembly error, an error-severity lint diagnostic, a mismatch in `verify`, a file that cannot be read |
+| `2` | the arguments were wrong: a missing or extra argument, an unknown command or format, an invalid `--map` pair |
+
+## Examples
+
+Assemble a kernel, check it, and run it:
+
+```sh
+gasm lint kernel_amd64.s
+gasm fmt -l kernel_amd64.s
+gasm asm -o kernel.bin kernel_amd64.s
+gasm verify --ground-truth kernel_amd64.s
+```
+
+Link the kernel into a Go program through the toolchain's own object format:
+
+```sh
+gasm asm --format goobj -p example.com/kernel -o kernel.o kernel_amd64.s
+```
+
+Find which labels a failing kernel reaches, headlessly:
+
+```sh
+gasm debug --func decodeBlockAVX2 --cover --script cmds.txt --timeout 30s kernel_amd64.s
+```

docs/DECISIONS.md

@@ -1,111 +0,0 @@
-# Deferred decisions
-
-Design decisions deliberately postponed, with enough context to pick them up
-again without re-deriving the analysis.  Each entry records what is deferred,
-why, the options on the table, and the trigger that should reopen it.
-
----
-
-## GOOBJ external (cross-package) symbol references
-
-**Status:** resolved (v0.29.0+, 2026-08-07).
-
-**Approach taken.**  Instead of parsing the compiler's iexport data (which
-would have required either `golang.org/x/tools` or an in-house parser), the
-resolver reads the **GOOBJ data directly** from the target package's `.a`
-archive.  The `.a` file contains a `_go_.o` member whose GOOBJ s is the
-same one gasm writes; the parser reuses the same layout (`blkSymdef`,
-`blkNonpkgdef`, the string table), so no new dependency was needed.
-
-**How it works.**
-
-1. `go list -json -export <pkg>` finds the target package's `.a` file.
-2. `extractGOOBJ` reads the ar archive, finds the `_go_.o` member, skips
-   the `"go object …\n!\n"` preamble and parses the GOOBJ header.
-3. `goobjFile.symbols()` walks `blkSymdef` and `blkNonpkgdef` in definition
-   order (the same order the linker uses) to build the symbol-to-index
-   mapping.
-4. `resolveExternalSymbols` wires the resolved `{PkgIdx, SymIdx}` into the
-   GOOBJ emission.
-
-The resolver is invoked automatically when `img.Externals` is non-empty; it
-runs `go list` as a subprocess (consistent with `toolchainObjectPreamble`
-which already calls `go tool asm`).  All symbol data is cached per package
-for the lifetime of the GOOBJ emission.
-
-## 2026-08-30 non-amd64 JIT execution trampolines
-
-**Status:** resolved for riscv64 (validated end to end under qemu-user)
-and arm64 (fix in place, consistent with the observed frame convention);
-open for loong64 until hardware validation.
-
-**Root cause (found 2026-08-31).**  The trampolines advanced SP past the
-leave-address slot after loading it, while the assembled kernels read
-their first argument at SP+8 per the frame convention (the amd64 path
-already kept SP on that slot).  Removing the advance fixed riscv64
-immediately (plain and checked ABI tests pass under qemu-user); the
-arm64 kernel's pre-fix trace showed exactly the same SP+8 reading.  The
-apparent arm64/loong64 "crashes in the JIT" turned out to be dominated
-by an unrelated instability: the Go 1.26 and 1.27 runtimes crash under
-qemu-user arm64 emulation (GC worker start, identical signature with the
-JIT tests skipped, both qemu 7.2 and 10.2), and the Go loong64 runtime
-does not start at all.  `gasm verify` therefore keeps loong64 kernels on
-the ground-truth path until hardware validation; the GOARCH-guarded
-tests (`verify/jit_arch_test.go`, `verify/abi_arch_test.go`) are the
-hardware validation entry point.
-
-**State.**  The per-architecture trampolines compile for all targets, the
-kernels they execute are byte-for-byte correct against `go tool asm`, and
-under `qemu-aarch64` the arm64 kernel demonstrably executes and stores its
-result correctly.  The failure is on the return path into Go code: arm64
-and loong64 take a SIGSEGV after the kernel's RET (the Go-side unwind
-through `leaveJIT` and its interposed ABIInternal wrapper is the suspect),
-and riscv64 returns cleanly but with an untouched result area.  amd64 is
-unaffected (the checked trampoline saves and restores BP/R14 and the flow
-is validated end to end).
-
-**Evidence harness.**  `verify/jit_arch_test.go` (plain call) and
-`verify/abi_arch_test.go` (checked call) are GOARCH-guarded tests; build
-the test binary per target (`GOARCH=arm64 go test -c -o v.test ./verify/`)
-and run it under `qemu-aarch64-static` from the `verify/` directory.  A
-minimal reproducer pattern lives in the qemu exploration notes: verify
-loads, the kernel executes, the fault follows the return.
-
-**Fix direction.**  Compare the amd64 checked trampoline (GLOBL/DATA raw
-address, explicit SP/BP/R14 save-restore) against the arm64/riscv64/
-loong64 `leaveJIT` unwind, in particular the interaction with the
-ABIInternal wrapper that `reflect.ValueOf(leaveJIT).Pointer()` returns.
-The plain-call path (no sentinels) fails the same way, so the checked
-path is not the variable.
-
----
-
-## 2026-08-29 tooling round
-
-- `lint abi0-register-args`: flags kernels whose `// func` parameters are
-  never read from the FP frame.  Motivated by a real latent bug: kernels
-  reading arguments from registers pass every test while the autogenerated
-  `F.abi0` wrapper happens to leave the caller's register values intact, and
-  break on a toolchain upgrade.
-- `lint nonportable-register-name`: the RAX/EAX register spellings are a gasm
-  extension; go tool asm rejects them, so files using them only link through
-  the gasm goobj path.
-- `lint unencodable-instruction`: a mnemonic in the architecture table that
-  `asm.Encodable` rejects is flagged at edit time instead of failing at
-  assembly time.
-- `audit-instructions`: black-box diff of the encoder against go tool asm.
-  As of this round the tables fully overlap on names; the audit exists to
-  catch drift in both directions (future supersets and future gaps).
-- `scaffold differential`: generates the direct-call differential skeleton
-  (two independent seed sets, output and in-place buffer comparison) that a
-  pipeline-level fuzz can never replace.
-- `verify --args`: scalar arguments for `-call`, closing the repro gap where
-  only buffers could be supplied.
-- `debug --script/--timeout/--cover`: headless debugging with a watchdog
-  armed before the ptrace attach (untracing sandboxes hang the attach), and
-  label-level block coverage for the "did my test ever enter that branch"
-  question.
-- Superset policy remains: gasm may accept spellings and encodings go tool
-  asm lacks, but such kernels ship only via `gasm asm --format goobj`; the
-  audit reports the superset surface.  The register-alias superset is warned
-  about by lint because the default `go build` path cannot consume it.

docs/DEVELOPMENT.md

@@ -4,79 +4,80 @@ Repository: [sourcedock.dev/petrbalvin/gasm-devkit](https://sourcedock.dev/petrb
 
 ## Prerequisites
 
-- **Go** 1.27+ with `toolchain go1.27.0`
+- **Go** 1.27.1, the exact version the `go` directive in `go.mod` declares
 - **just**, the command runner; every task below is a just recipe
+- A Linux host on amd64, arm64, riscv64 or loong64: `gasm debug` needs ptrace
+  and the JIT checks of `gasm verify` need executable memory
 - No external dependencies beyond the Go toolchain
 
-## Quick Start
+## Setup
 
 ```sh
 git clone https://sourcedock.dev/petrbalvin/gasm-devkit.git
 cd gasm-devkit
-just install   # go mod download
+just build     # compile bin/gasm, zero errors and zero warnings
-just build     # go vet + gofmt, must pass with zero output
+just gates     # build, fmt-check, vet, test, race: the definition of done
-just test      # full suite, race detector, 80 % coverage gate
 ```
 
-## Just Recipes
+## Recipes
 
-### `just install`
+Every recipe in the `justfile`, and what it does.
 
-`go mod download`.  The only module dependency, `golang.org/x/arch`, is
+| Recipe | What it does |
-used in tests only.
+|---|---|
-
+| `just build` | compiles `bin/gasm` with `CGO_ENABLED=0` and stripped symbols; zero errors and zero warnings |
-### `just build`
+| `just test` | the test gate: the suite with `-count=1`, the coverage profile and the 80 % floor |
-
+| `just race` | the same suite under the race detector; the expensive one, so it runs once, inside `gates` |
-Runs `go vet ./...` and checks `gofmt -l .` produces no output. This is
+| `just unit [packages] [run]` | fast, cached, scoped run for iterating: no race and no coverage, so an unchanged package reports instantly |
-the minimum bar before any commit.
+| `just fuzz <target> <pkg> [fuzztime]` | time-boxed fuzz of one target; the package is required, because `go test -fuzz` refuses more than one |
+| `just bench [packages]` | benchmarks (`-benchmem -count=5`); on an idle machine only |
+| `just fmt` | formats the tree in place with `gofmt` |
+| `just fmt-check` | zero diff; prints nothing when everything is formatted, which is the shape the CI step wants |
+| `just vet` | both static gates: `go vet` and `go fix -diff` |
+| `just gates` | `build`, `fmt-check`, `vet`, `test` and `race`, in that order: the definition of done |
+| `just clean` | removes the build artefacts, `bin/` and `coverage.out` |
+| `just install` | builds, then copies the binary into `bindir` (`~/.local/bin`); `gasm debug` needs an installed binary, because it spawns the debuggee from `$PATH` |
+| `just uninstall` | removes the installed binary from `bindir` |
+| `just run` | runs the CLI with `go run -buildvcs=true`; the recipe takes no arguments, so flags go through the package instead |
+| `just dev` | the same as `run`; the project has no watcher to add |
+| `just gen` | regenerates the `arch` instruction tables from the Go toolchain source; not a gate |
 
 ### `just test`
 
 ```sh
-go test -race -count=1 ./...
+go test -count=1 -timeout 10m -coverprofile=coverage.out \
+    ./arch/... ./asm/... ./ast/... ./disasm/... ./format/... ./lexer/... \
+    ./lint/... ./lsp/... ./parser/... ./token/... ./verify/...
 ```
 
-Plus a coverage run over the ten analysable packages (arch, asm, ast,
+The suite runs over the logic packages (`-count=1`, so no cached pass
-format, lexer, lint, lsp, parser, token, verify; `debug` and `cmd/gasm`
+counts): arch, asm, ast, disasm, format, lexer, lint, lsp, parser,
-need hardware or are CLI glue) and an `awk` gate that fails if total
+token, verify. `debug` traces a live process and `cmd/gasm` is thin CLI
-coverage is below 80 %.
+glue, so both sit outside the sweep, and a thin `cmd/` in it would drag
+the coverage total under the floor. The floor fails if the total is
+below 80 %.  CI runs the same command with the same ten-minute bound, so
+the number is the same everywhere.
 
-### `just fmt`
+### `just run`
 
 ```sh
-gofmt -w .
+just run
+go run -buildvcs=true ./cmd/gasm lint kernel_amd64.s
+go run -buildvcs=true ./cmd/gasm verify --ground-truth kernel_amd64.s
 ```
 
-Run after editing any Go source. The output must be idempotent.
+The flag on `go run` is there because it does not stamp the build otherwise,
-
+which `--version` would then report as `(devel)`.
-### `just run -- <args>`
-
-Runs the CLI via `go run` with the version string stamped:
-
-```sh
-just run -- lint kernel_amd64.s
-just run -- fmt -w kernel_amd64.s
-just run -- verify --ground-truth kernel_amd64.s
-```
-
-### `just install-bin`
-
-Installs the `gasm` binary into `$GOBIN` with the release version
-embedded via `-ldflags "-X main.version=..."`.
 
 ### `just gen`
 
-Regenerates the architecture instruction tables in `arch/` by parsing
+Regenerates the architecture instruction tables in `arch/` by parsing the Go
-the Go toolchain's own assembler source
+toolchain's own assembler source
 (`$GOROOT/src/cmd/internal/obj/<arch>/anames.go`). Requires a Go
 installation. Output is committed, with no runtime dependency on the
 toolchain.
 
-### `just uninstall`
+## Running a single test
-
-Removes `coverage.out`, the `gasm` binary, and `*.test` artefacts.
-
-## Running Individual Tests
 
 ```sh
 go test -run TestVexGroundTruth ./asm/
@@ -85,32 +86,53 @@ go test -run TestGOObjectLinkAndRun ./asm/
 go test -run TestFuzzWideCopy ./verify/
 ```
 
-## Debugger Note
+Add `-v` for the sub-test names, and `-race` when the change touches
+concurrency. `-count=1` defeats the test cache when a result looks stale.
 
-`gasm debug` spawns a child process from the binary on `$PATH`. It does
+## Coverage
-not work with `go run`; install first:
 
 ```sh
-just install-bin
+just test
-gasm debug --func decodeBlockAVX2 path/to/kernel_amd64.s
+go tool cover -func=coverage.out
 ```
 
-## Project Layout
+The `total:` line is the number that matters, and it stays at 80 percent or
+more.
 
+## Debugging the build
+
+```sh
+go build -gcflags='-m' ./...    # inlining decisions
+go build -gcflags='-S' ./...    # what the compiler generated
+go tool asm -S kernel_amd64.s   # how the toolchain's assembler encodes a kernel
+gasm dis kernel_amd64.s         # what gasm makes of the same kernel
+gasm tokens kernel_amd64.s      # the token stream
+gasm profile kernel_amd64.s     # the basic blocks of each function
 ```
-cmd/gasm/           CLI entry point (subcommands)
+
-token/              Lexical token kinds and positions
+`gasm verify --ground-truth` is the differential check that ties the two
-lexer/              Hand-written scanner
+together: it compares gasm's bytes with `go tool asm`'s, with the relocation
-ast/                Abstract syntax tree
+sites masked, so an encoding drift shows up as a byte difference rather than a
-parser/             Line-oriented parser
+crash later.
-arch/               Register and instruction tables (generated)
+
-lint/               Static analysis rules
+## Continuous integration
-format/             Canonical formatter
+
-lsp/                Language Server Protocol server
+Workflows live in `.gitea/workflows/` and run on the project's own runners:
-asm/                Standalone assembler, encoder, object emitters
+Test on a push or pull request to `development`, race dispatched by hand, and
-verify/             JIT execution, differential testing, ABI checks
+the release on a `v*` tag.  They are written by hand rather than through
-debug/              Interactive ptrace debugger (all four architectures)
+`just`, but they enforce the same set of gates minus the race detector, which
-_gen/               Instruction table generator
+the shared runner cannot afford on a push; a green `just gates` locally is
-testdata/           Test fixtures
+therefore the fastest way to a green pipeline.
-docs/               Architecture, development, CLI reference
+
-```
+## Releases
+
+Releases are cut by merging `development` into `main` and tagging `vX.Y.Z`,
+which triggers the release workflow: it builds the portable Linux targets,
+takes the notes from the matching `CHANGELOG.md` section and uploads the
+assets.
+
+The version is never injected. `gasm --version` prints what the
+toolchain recorded in the build information: the tag on a tagged
+checkout, a pseudo-version naming the commit below one, `+dirty` on a
+dirty tree, and `(devel)` outside version control. There is no
+`-ldflags "-X"` anywhere and no version constant in the source.

docs/man/gasm-asm.1

@@ -0,0 +1,62 @@
+.TH GASM-ASM 1 "2026-09-19" "gasm 0.33.0" "User Commands"
+.SH NAME
+gasm-asm \- assemble Plan 9 assembly without the Go toolchain
+.SH SYNOPSIS
+.B gasm asm [\-\-format raw|elf|goobj] [\-p pkg] [\-GOARCH arch] [\-o out] <file>
+.SH DESCRIPTION
+Assemble FILE without the Go toolchain: every TEXT function is encoded
+to machine code and printed as a hex dump.  Supported architectures:
+amd64 (including VEX/AVX2 and EVEX/AVX-512), arm64 (AArch64 integer,
+FP, conditional select, CRC32 and MOV pseudo), riscv64 (RV64IMAFDC and
+RVC) and loong64 (LoongArch base ISA).
+.PP
+With
+.B \-o
+the output is written to a file instead.  The
+.B \-\-format
+flag selects what is written:
+.B raw
+(the default) concatenates the functions and the data section into one
+self-consistent image;
+.B elf
+emits a relocatable object (.text/.data sections, a symbol table and
+one PC32 relocation per static-symbol reference) that links with the
+system toolchain;
+.B goobj
+emits the Go toolchain's own object format, which cmd/link consumes
+directly (it requires
+.BR \-p ,
+the package path, and the installed Go toolchain).
+.PP
+Framed functions receive the stack-split guard and the trailing
+morestack block, byte-identical to the toolchain's output, so split
+functions link too.
+.SH OPTIONS
+.TP
+.B \-\-format \fIraw|elf|goobj\fR
+Output format; the default is raw.
+.TP
+.B \-p \fIpkg\fR
+Package path for --format goobj, qualifying the exported symbols.
+.TP
+.B \-GOARCH \fIarch\fR
+Target architecture: amd64, arm64, riscv64 or loong64; overrides the
+file-name suffix, which is how the suffix-less majority of GOROOT's
+files (cpu_x86.s, stub.s, ...) become assemblable.
+.TP
+.B \-o \fIfile\fR
+Write the output to this file instead of a hex dump on stdout.
+.SH EXIT STATUS
+Exits 0 on success, 1 when parsing or assembly fails, and 2 on a usage
+error.
+.SH EXAMPLES
+.nf
+gasm asm \-o hello.bin hello_amd64.s               raw image
+gasm asm \-\-format elf \-o k.o k.s                 linkable ELF object
+gasm asm \-\-format goobj \-p pkg/path \-o k.o k.s   Go object for go build
+gasm asm \-GOARCH amd64 cpu_x86.s                  arch override
+.fi
+.SH SEE ALSO
+.BR gasm (1),
+.BR gasm\-dis (1),
+.BR gasm\-verify (1)

docs/man/gasm-audit-instructions.1

@@ -0,0 +1,47 @@
+.TH GASM-AUDIT-INSTRUCTIONS 1 "2026-09-19" "gasm 0.33.0" "User Commands"
+.SH NAME
+gasm-audit-instructions \- diff the encoder against the Go toolchain, or measure a corpus
+.SH SYNOPSIS
+.B gasm audit\-instructions [\-\-corpus [\fIdir\fR]] [amd64|arm64|riscv64|loong64]
+.SH DESCRIPTION
+Compare the gasm encoder for the given architecture (default amd64)
+against
+.B go tool asm
+and print the diff: superset encodings (gasm-only, shippable via
+.BR "gasm asm \-\-format goobj" ),
+known-but-unencodable names (the backlog) and go-only names (feature
+gaps).  The Go side is probed black-box with a battery of bare
+mnemonics, so the audit tracks whatever toolchain
+.B go env GOROOT
+provides.
+.PP
+With
+.BR \-\-corpus ,
+the audit changes shape: it assembles every
+.I .s
+file under the given directory (default GOROOT/src) with the gasm
+encoder only, no toolchain probing.  A file whose name carries a
+recognisable _arch suffix is attempted for that architecture; a file
+without one is attempted for all four, exactly as a GOARCH build would
+compile it.  The report gives the headline number (files that assemble
+for every target architecture), the per-architecture pass rates and the
+most common failure reasons, which drive the encodability backlog by
+frequency rather than by table order.  A run over GOROOT takes under a
+second.
+.SH OPTIONS
+.TP
+.B \-\-corpus [\fIdir\fR]
+Assemble a corpus of .s files and report pass rates and failure
+reasons.
+.SH EXIT STATUS
+The mnemonic-diff mode reports through its output and exits 0; a failed
+probe or an unknown architecture exits non-zero.
+.SH EXAMPLES
+.nf
+gasm audit\-instructions amd64
+gasm audit\-instructions \-\-corpus
+gasm audit\-instructions \-\-corpus "$(go env GOROOT)/src/crypto"
+.fi
+.SH SEE ALSO
+.BR gasm (1),
+.BR gasm\-asm (1)

docs/man/gasm-debug.1

@@ -0,0 +1,113 @@
+.TH GASM-DEBUG 1 "2026-09-19" "gasm 0.33.0" "User Commands"
+.SH NAME
+gasm-debug \- interactive source-level debugger for JIT-assembled functions
+.SH SYNOPSIS
+.B gasm debug <file.s> \-\-func <name>
+.SH DESCRIPTION
+Interactive debugger for JIT-assembled functions.  Launches the function
+in a traced subprocess (ptrace), then provides a REPL for
+single-stepping, breakpoints, register and memory inspection.
+.PP
+With
+.B \-\-script
+the REPL commands run from a file and the session ends: the headless
+mode CI and scripts use.
+.B \-\-cover
+runs to completion with a breakpoint on every instruction and reports
+which executed and how often, the label-level coverage view.
+.SH REPL COMMANDS
+.TP
+.B break \fIlabel|addr\fR [\fBif \fIreg op val\fR]
+Set a breakpoint, optionally conditional on a register comparison
+(register against register or immediate).
+.TP
+.B delete \fIlabel|addr\fR
+Remove a breakpoint.
+.TP
+.B info break
+List all breakpoints.
+.TP
+.BR step " [" n ], " s
+Single-step n instructions; the default is 1.
+.TP
+.BR next ", " n
+Step over a CALL.
+.TP
+.BR finish ", " fin
+Run until the function returns.
+.TP
+.BR continue ", " c
+Run until a breakpoint, watchpoint or exit.
+.TP
+.BR disas " [" n ], " u
+Disassemble n instructions at PC.
+.TP
+.B regs
+Print general-purpose and vector registers.
+.TP
+.B where
+Show the source line and nearest label at PC.
+.TP
+.B stack
+Show the stack near RSP (return address and ABI0 args).
+.TP
+.BR bt ", " backtrace
+Backtrace: current frame plus return address.
+.TP
+.B x [\fIaddr\fR] [\fIlen\fR]
+Hex-dump memory; the defaults are the current PC and 64 bytes.
+.TP
+.B w \fIaddr val...\fR
+Write bytes to memory.
+.TP
+.B set \fIreg value\fR
+Set a register.
+.TP
+.B watch \fIaddr\fR [\fBr|w\fR] [\fIsize\fR]
+Set a hardware watchpoint; writes are watched by default.
+.TP
+.B unwatch [\fIslot\fR]
+Clear one watchpoint, or all without an argument.
+.TP
+.BR labels ", " l
+List function labels and offsets.
+.TP
+.BR help ", " h ", " ?
+Show command help.
+.TP
+.BR quit ", " q
+Kill the debuggee and exit.
+.SH OPTIONS
+.TP
+.B \-args \fIfile\fR
+File containing the ABI0 argument block.
+.TP
+.B \-buf \fIspec\fR
+Buffer specification: name:size:pattern[,name:size:pattern...] where
+pattern is zero, ones, seq, or hex.
+.TP
+.B \-cover
+Run to completion with a breakpoint on every instruction and report
+which executed and how often.
+.TP
+.B \-func \fIname\fR
+Function to debug.
+.TP
+.B \-script \fIfile\fR
+Run REPL commands from a file (one per line) and exit; - reads stdin.
+.TP
+.B \-timeout \fIduration\fR
+Kill the debuggee after this duration (e.g. 30s); for headless --script
+runs.
+.SH EXIT STATUS
+Exits 0 when the scripted session completes and 1 when the debuggee
+crashes or a check fails; the debugger is Linux-only.
+.SH EXAMPLES
+.nf
+gasm debug \-\-func name k.s
+gasm debug \-\-func name \-\-script cmds.txt \-\-timeout 30s k.s
+gasm debug \-\-func name \-\-cover k.s
+.fi
+.SH SEE ALSO
+.BR gasm (1),
+.BR gasm\-verify (1)

docs/man/gasm-diff.1

@@ -0,0 +1,35 @@
+.TH GASM-DIFF 1 "2026-09-19" "gasm 0.33.0" "User Commands"
+.SH NAME
+gasm-diff \- compare the machine code of two assembly files
+.SH SYNOPSIS
+.B gasm diff [\-GOARCH arch] <file1.s> <file2.s>
+.SH DESCRIPTION
+Compare the machine code produced by assembling two files.  Shows which
+functions differ and the byte-level differences.  Useful for verifying
+that two implementations produce identical code, or for tracking
+encoding changes between Go assembler versions.
+.PP
+Functions are paired by exact name unless
+.B \-\-map
+says otherwise, so
+.B \-\-map wideCopyAVX2=wideCopyAVX512
+pairs two variants regardless of suffix.
+.SH OPTIONS
+.TP
+.B \-GOARCH \fIarch\fR
+Target architecture for both files: amd64, arm64, riscv64 or loong64;
+overrides the file-name suffixes.
+.TP
+.B \-\-map \fIspec\fR
+Comma-separated old=new pairs to match functions with different names.
+.SH EXIT STATUS
+Exits 0 when every paired function is identical and 1 when anything
+differs; a usage error exits 2.
+.SH EXAMPLES
+.nf
+gasm diff hello_amd64.s hello_amd64.s
+gasm diff \-\-map wideCopyAVX2=wideCopyAVX512 avx2.s avx512.s
+.fi
+.SH SEE ALSO
+.BR gasm (1),
+.BR gasm\-asm (1)

docs/man/gasm-dis.1

@@ -0,0 +1,36 @@
+.TH GASM-DIS 1 "2026-09-19" "gasm 0.33.0" "User Commands"
+.SH NAME
+gasm-dis \- disassemble machine code to instruction text
+.SH SYNOPSIS
+.B gasm dis [\-a arch] <file>
+.SH DESCRIPTION
+Disassemble machine code to instruction text, decoded through
+golang.org/x/arch.
+.PP
+With a
+.I .s
+file, the file is assembled first and the listing follows the real
+layout: one block per TEXT function, local labels printed at their
+offsets.  The architecture comes from the file-name suffix, or from
+.BR \-a .
+.PP
+With any other file, or
+.B \-
+for standard input, the bytes are disassembled linearly and
+.B \-a
+selects the architecture (amd64, arm64, riscv64 or loong64).
+.SH OPTIONS
+.TP
+.B \-a \fIarch\fR
+Architecture for raw input: amd64, arm64, riscv64 or loong64.
+.SH EXIT STATUS
+Exits 0 on success, 1 when assembly or decoding fails, and 2 on a usage
+error.
+.SH EXAMPLES
+.nf
+gasm dis k.s                          assemble, then list each function
+gasm dis \-a amd64 \- < dump.bin        disassemble raw bytes from stdin
+.fi
+.SH SEE ALSO
+.BR gasm (1),
+.BR gasm\-asm (1)

docs/man/gasm-fmt.1

@@ -0,0 +1,52 @@
+.TH GASM-FMT 1 "2026-09-19" "gasm 0.33.0" "User Commands"
+.SH NAME
+gasm-fmt \- canonicalise the formatting of Plan 9 assembly sources
+.SH SYNOPSIS
+.B gasm fmt [\-w|\-l|\-d] [path...]
+.SH DESCRIPTION
+Canonicalise the formatting of Plan 9 assembly sources: indentation,
+operand spacing, per-function mnemonic alignment and blank-line layout
+(exactly one blank line before each label, TEXT and GLOBL block).
+Formatting is idempotent and preserves every line, comments included.
+.PP
+With no paths, or a directory path, every
+.I .s
+file below it is reformatted in place and the changed files are listed,
+the way
+.B go fmt
+does;
+.B .
+and
+.B _
+directories are skipped.  Explicit file paths print to stdout unless
+.B \-w
+is given.
+.PP
+.B \-l
+and
+.B \-d
+rewrite nothing:
+.B \-l
+prints the paths whose formatting differs from gasm's (empty output
+means everything is formatted, which is what a CI check wants),
+.B \-d
+prints the diffs.  They are mutually exclusive.
+.SH OPTIONS
+.TP
+.B \-d
+Print diffs instead of rewriting files.
+.TP
+.B \-l
+List files whose formatting differs from gasm's.
+.TP
+.B \-w
+Write the result to the source file.
+.SH EXAMPLES
+.nf
+gasm fmt                                reformat every .s below here
+gasm fmt \-w kernel_amd64.s              canonicalise one file in place
+gasm fmt \-l *.s                         list files whose formatting differs
+gasm fmt \-d kernel_amd64.s              print a unified diff instead
+.fi
+.SH SEE ALSO
+.BR gasm (1)

docs/man/gasm-lint.1

@@ -0,0 +1,90 @@
+.TH GASM-LINT 1 "2026-09-19" "gasm 0.33.0" "User Commands"
+.SH NAME
+gasm-lint \- run the static checks over assembly files
+.SH SYNOPSIS
+.B gasm lint <file...>
+.SH DESCRIPTION
+Run the static checks over the given files and print diagnostics as
+\fIfile:line:col: severity: message [code]\fR.  The exit status is
+non-zero when an error-severity diagnostic is found; warnings (e.g. the
+register-clobber audit) do not affect it.
+.PP
+The checks are conservative: they report what can be proven wrong and
+stay quiet otherwise, so a clean lint run is meaningful without
+suppression lists.
+.SH RULES
+.TP
+.B unknown-instruction
+The mnemonic is not in the architecture's instruction table.
+.TP
+.B operand-count
+The operand count disagrees with the instruction's declared arity.
+.TP
+.B undefined-label
+A jump target names no label in the function.
+.TP
+.B duplicate-label
+Two labels in one function share a name.
+.TP
+.B missing-ret
+The function can fall off its end without a terminator.
+.TP
+.B missing-textflag-include
+TEXT flags are used without including textflag.h.
+.TP
+.B abi-argsize
+The declared frame or argument size disagrees with the
+.B //\ function
+signature.
+.TP
+.B unreachable-code
+Code after RET and before the next label is dead; suppressed for
+functions with PC-relative or register-indirect control flow.
+.TP
+.B register-clobber
+A register the Go ABI fixes across calls is written without save and
+restore, computed by liveness over the control-flow graph.
+.TP
+.B funcdata-pcdata
+FUNCDATA and PCDATA indices are malformed.
+.TP
+.B unused-label
+A label no jump reaches.
+.TP
+.B invalid-textflag
+A TEXT flag combination the toolchain rejects.
+.TP
+.B stack-imbalance
+The function does not restore the stack pointer on every path.
+.TP
+.B register-width-mismatch
+An operand register has the wrong width for the instruction.
+.TP
+.B abi0-register-args
+A call passes arguments in registers where ABI0 expects the stack
+frame.
+.TP
+.B nonportable-register-name
+A register spelling that does not exist on the target architecture.
+.TP
+.B unencodable-instruction
+The mnemonic is known to the table but the encoder cannot assemble it
+yet (amd64).
+.TP
+.B reserved-register-write
+A write to the register the runtime reserves (arm64 R18).
+.SH OPTIONS
+.TP
+.B \-disable \fIcodes\fR
+Comma-separated rule codes to disable.
+.SH EXIT STATUS
+Exits 0 when no error-severity diagnostic is found, 1 otherwise, and 2
+on a usage error.
+.SH EXAMPLES
+.nf
+gasm lint kernel_amd64.s
+gasm lint \-disable register-clobber,unused-label *.s
+.fi
+.SH SEE ALSO
+.BR gasm (1),
+.BR gasm\-asm (1)

docs/man/gasm-lsp.1

@@ -0,0 +1,24 @@
+.TH GASM-LSP 1 "2026-09-19" "gasm 0.33.0" "User Commands"
+.SH NAME
+gasm-lsp \- run the Plan 9 assembly language server
+.SH SYNOPSIS
+.B gasm lsp
+.SH DESCRIPTION
+Run the language server over standard input/output: JSON-RPC 2.0 with
+Content-Length framing.  Point an LSP-capable editor at the binary and
+associate it with
+.I .s
+files; the target architecture is inferred from the file suffix
+(_amd64.s, _arm64.s, _riscv64.s, _loong64.s).
+.PP
+Provides completion, hover, document symbols, push and pull
+diagnostics, semantic-token highlighting, go-to-definition, find
+references, rename, formatting, inlay hints, code actions, signature
+help, document highlights, workspace symbol search, include document
+links and folding ranges; definition, references and rename work across
+every open document.  Syntax highlighting is delivered as LSP semantic
+tokens, so no editor-specific grammar is required.
+.SH EXIT STATUS
+Runs until the client closes the session; exits 0 on a clean shutdown.
+.SH SEE ALSO
+.BR gasm (1)

docs/man/gasm-parse.1

@@ -0,0 +1,20 @@
+.TH GASM-PARSE 1 "2026-09-19" "gasm 0.33.0" "User Commands"
+.SH NAME
+gasm-parse \- parse an assembly file and report syntax errors
+.SH SYNOPSIS
+.B gasm parse <file>
+.SH DESCRIPTION
+Parse FILE and report syntax errors on stderr.  The parser is
+error-tolerant and line-oriented: a malformed line becomes a diagnostic
+and parsing continues, so one run reports every syntax error in the
+file rather than the first.
+.PP
+On success, print how many declarations and TEXT functions the file
+contains.  FILE may be
+.B \-
+to read standard input.
+.SH EXIT STATUS
+Exits 0 when the file parses without errors and 1 otherwise.
+.SH SEE ALSO
+.BR gasm (1),
+.BR gasm\-tokens (1)

docs/man/gasm-profile.1

@@ -0,0 +1,16 @@
+.TH GASM-PROFILE 1 "2026-09-19" "gasm 0.33.0" "User Commands"
+.SH NAME
+gasm-profile \- show the basic-block structure of functions
+.SH SYNOPSIS
+.B gasm profile <file.s>
+.SH DESCRIPTION
+Show the basic-block structure of functions in an assembly file: each
+function's labels, their offsets, and the block boundaries.  This is
+the static structure; for runtime execution counts, use
+.BR "gasm verify \-fuzz" ,
+which exercises the code paths.
+.SH EXIT STATUS
+Exits 0 on success and 1 when the file cannot be assembled.
+.SH SEE ALSO
+.BR gasm (1),
+.BR gasm\-verify (1)

docs/man/gasm-scaffold.1

@@ -0,0 +1,22 @@
+.TH GASM-SCAFFOLD 1 "2026-09-19" "gasm 0.33.0" "User Commands"
+.SH NAME
+gasm-scaffold \- generate a differential test skeleton for a kernel file
+.SH SYNOPSIS
+.B gasm scaffold differential <file.s>
+.SH DESCRIPTION
+Print a differential test skeleton for every
+.B //\ func
+signature in FILE.  The test seeds random states, drives the kernel and
+a portable reference (\fI<name>Portable\fR), and compares outputs
+byte-for-byte.  Write the reference bodies, place the file in the
+kernel's package, and run it in CI.
+.SH EXIT STATUS
+Exits 0 when the skeleton is written to stdout and 1 when the file
+cannot be parsed; a usage error exits 2.
+.SH EXAMPLES
+.nf
+gasm scaffold differential kernel_amd64.s > kernel_differential_test.go
+.fi
+.SH SEE ALSO
+.BR gasm (1),
+.BR gasm\-verify (1)

docs/man/gasm-tokens.1

@@ -0,0 +1,19 @@
+.TH GASM-TOKENS 1 "2026-09-19" "gasm 0.33.0" "User Commands"
+.SH NAME
+gasm-tokens \- print the lexical token stream of an assembly file
+.SH SYNOPSIS
+.B gasm tokens <file>
+.SH DESCRIPTION
+Print the lexical token stream of FILE: position, token kind and text,
+one token per line.  FILE may be
+.B \-
+to read standard input.
+.PP
+This is the front end's raw view, for when the assembler's own
+diagnostic is not enough: a mis-scanned operand or a swallowed comment
+shows up here as the tokens the parser actually received.
+.SH EXIT STATUS
+Exits 0 on success and 1 when the file cannot be read.
+.SH SEE ALSO
+.BR gasm (1),
+.BR gasm\-parse (1)

docs/man/gasm-verify.1

@@ -0,0 +1,117 @@
+.TH GASM-VERIFY 1 "2026-09-19" "gasm 0.33.0" "User Commands"
+.SH NAME
+gasm-verify \- JIT-assemble a file and run dynamic checks against it
+.SH SYNOPSIS
+.B gasm verify [\-smoke] [\-abi] [\-fuzz] [\-ground\-truth] [\-profile] [\-call] <file.s>
+.SH DESCRIPTION
+Assemble FILE, map it into executable memory and report the available
+functions.  This confirms the assembled image is self-consistent (no
+unresolved external symbols) and executable, the prerequisite for
+dynamic testing.
+.PP
+With
+.BR \-smoke ,
+each NOSPLIT function is called with a zeroed argument block to confirm
+the JIT trampoline works end-to-end.  This is safe only for functions
+that tolerate nil pointers and zero lengths in their arguments.
+.PP
+With
+.BR \-abi ,
+each function is called with sentinel values in the registers the Go
+ABI fixes across calls (the frame pointer and the goroutine pointer)
+plus a canary below SP; violations are reported.  JIT-based checks run
+when the host matches the file's architecture (all but loong64, which
+is ground-truth only for now).
+.PP
+With
+.BR \-fuzz ,
+each function with a
+.B //\ func
+signature is differentially fuzzed against the go-tool-asm version in a
+subprocess (so a crash on a partial function is reported, not fatal).
+.PP
+With
+.BR \-ground\-truth ,
+the assembled machine code is compared byte-for-byte against
+.B go tool asm
+(relocation sites masked), reporting any encoding drift.
+.PP
+With
+.BR \-profile ,
+the static basic-block structure is listed for each function.
+.PP
+With
+.BR \-call ,
+a single function is invoked with user-supplied buffers
+.RB ( \-buf )
+instead of the smoke/abi/fuzz sweeps.  Useful for partial functions
+(e.g. decoders) that crash on random input but should succeed on valid
+data.
+.PP
+With
+.B \-save\-corpus
+(and
+.BR \-fuzz ),
+every input that crashes or mismatches is written to the directory as
+replayable JSON.
+.B \-replay
+re-runs saved entries against the kernel, one child process per entry,
+so an input that crashed the original run crashes only the child: the
+report says whether each entry reproduces.
+.SH OPTIONS
+.TP
+.B \-abi
+Run ABI-checking calls (sentinel registers and red zone).
+.TP
+.B \-abi\-n \fIn\fR
+Number of ABI check iterations with varied inputs; the default is 100.
+.TP
+.B \-args \fIspec\fR
+Scalar args for -call: name=value[,name=value] (decimal or 0x hex).
+.TP
+.B \-buf \fIspec\fR
+Buffer spec for -call: name:size:pattern[,name:size:pattern] where
+pattern is zero, ones, seq, or hex.
+.TP
+.B \-call \fIname\fR
+Call a single function with -buf instead of the sweeps.
+.TP
+.B \-fuzz
+Differential fuzz: JIT both the gasm and the go-tool-asm versions and
+compare outputs.
+.TP
+.B \-ground\-truth
+Compare machine code byte-for-byte against go tool asm.
+.TP
+.B \-n \fIn\fR
+Number of fuzz iterations per function; the default is 1000.
+.TP
+.B \-profile
+List basic-block structure per function.
+.TP
+.B \-repeat \fIn\fR
+Number of times to repeat a -call invocation; the default is 1.
+.TP
+.B \-replay \fIdir\fR
+Replay saved corpus entries (JSON files in this directory) against the
+kernel.
+.TP
+.B \-save\-corpus \fIdir\fR
+With -fuzz: write each failing input to this directory as replayable
+JSON.
+.TP
+.B \-smoke
+Call each NOSPLIT function with zeroed args.
+.SH EXIT STATUS
+Exits 0 when every requested check passes and 1 when any check fails;
+a file that cannot be assembled exits 1 and a usage error exits 2.
+.SH EXAMPLES
+.nf
+gasm verify \-\-call add \-\-args a=2,b=3 hello_amd64.s
+gasm verify \-\-ground\-truth k.s
+gasm verify \-\-fuzz \-n 500 k.s
+.fi
+.SH SEE ALSO
+.BR gasm (1),
+.BR gasm\-asm (1),
+.BR gasm\-debug (1)

docs/man/gasm.1

@@ -0,0 +1,96 @@
+.TH GASM 1 "2026-09-19" "gasm 0.33.0" "User Commands"
+.SH NAME
+gasm \- developer tooling for Go's Plan 9 assembler
+.SH SYNOPSIS
+.B gasm
+.I command
+.RI [ arguments ]
+.br
+.B gasm
+.BR \-h | \-\-help
+.br
+.B gasm
+.BR \-V | \-\-version
+.SH DESCRIPTION
+.B gasm
+bundles a lexer, parser, formatter, linter, standalone assembler and
+language server for Plan 9 assembly into one self-contained binary.  It
+serves two purposes: it brings developer tooling to the
+.I .s
+files of Go programs, and it assembles Plan 9 assembly without the Go
+toolchain at all, to raw images, linkable ELF objects with DWARF5 debug
+sections, or the Go toolchain's own GOOBJ format, which
+.B go build
+consumes directly.
+.PP
+Four architectures are covered: amd64 (including VEX/AVX2 and
+EVEX/AVX-512), arm64, riscv64 (RV64IMAFDC and RVC) and loong64.  The
+target architecture is inferred from the file-name suffix
+(\fI_amd64.s\fR, \fI_arm64.s\fR, \fI_riscv64.s\fR, \fI_loong64.s\fR) or
+named explicitly with \fB\-GOARCH\fR where the commands accept it.
+.SH COMMANDS
+.TP
+.B gasm\-tokens(1)
+Print the lexical token stream.
+.TP
+.B gasm\-parse(1)
+Parse a file and report syntax errors.
+.TP
+.B gasm\-fmt(1)
+Canonicalise formatting: gofmt for assembly.
+.TP
+.B gasm\-lint(1)
+Run the static checks.
+.TP
+.B gasm\-asm(1)
+Assemble \fI.s\fR files to machine code, raw images, ELF objects or GOOBJ.
+.TP
+.B gasm\-dis(1)
+Disassemble machine code, raw bytes or an assembled \fI.s\fR file.
+.TP
+.B gasm\-verify(1)
+JIT-assemble and run dynamic checks: smoke calls, ABI checks,
+differential fuzzing, ground-truth comparison.
+.TP
+.B gasm\-debug(1)
+Interactive source-level debugger.
+.TP
+.B gasm\-diff(1)
+Compare the machine code of two files byte-for-byte.
+.TP
+.B gasm\-profile(1)
+Show the basic-block structure of functions.
+.TP
+.B gasm\-audit\-instructions(1)
+Diff the encoder against the Go toolchain's name table, or measure a
+corpus of \fI.s\fR files.
+.TP
+.B gasm\-scaffold(1)
+Generate a differential test skeleton for a kernel file.
+.TP
+.B gasm\-lsp(1)
+Run the language server over standard input/output.
+.TP
+.B gasm version
+Print the version, the same as \fB\-\-version\fR.
+.SH GLOBAL FLAGS
+.TP
+.BR \-h ", " \-\-help
+Show the command overview.
+.TP
+.BR \-V ", " \-\-version
+Print the version the toolchain recorded at build time.
+.SH EXIT STATUS
+Exits 0 on success, 1 when a command fails, and 2 on a usage error.  An
+unknown command exits 2.
+.SH SEE ALSO
+.BR gasm\-asm (1),
+.BR gasm\-fmt (1),
+.BR gasm\-lint (1),
+.BR gasm\-verify (1),
+.BR gasm\-debug (1)
+.PP
+The full command reference, with worked examples and every flag, is in
+docs/CLI.md of the repository
+.UR https://sourcedock.dev/petrbalvin/gasm-devkit
+.UE .

format/format.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
 // SPDX-License-Identifier: BSD-3-Clause
 
-// Package format implements a canonical formatter for GAsm source — the
+// Package format implements a canonical formatter for GAsm source, the
 // equivalent of gofmt for Plan 9 assembly.  It works on the token stream
 // rather than the AST so that every line (including comments and blanks) is
 // preserved; it only normalises indentation, operand spacing and per-function
@@ -50,15 +50,34 @@ func Source(src string) string {
 				}
 			case len(line) >= 2 && line[1].Kind == token.Colon:
 				inf.kind = kLabel
+				// Peel stacked labels exactly as the render pass does; the
+				// instruction after the last one is rendered at the
+				// function's alignment width, so its mnemonic counts here.
+				rest := line[2:]
+				for len(rest) >= 2 && rest[0].Kind == token.Ident && rest[1].Kind == token.Colon &&
+					!isDirective(rest[0].Text) {
+					rest = rest[2:]
+				}
+				if len(rest) > 0 && rest[0].Kind == token.Ident && !isDirective(rest[0].Text) {
+					inf.mnemLen = len(rest[0].Text)
+					if funcID >= 0 && inf.mnemLen > maxWidth[funcID] {
+						maxWidth[funcID] = inf.mnemLen
+					}
+				}
 			default:
 				inf.kind = kInstr
 				inf.funcID = funcID
+				// Only an identifier mnemonic takes the alignment width; a
+				// line starting with anything else renders unpadded, so its
+				// length must not enter the width either.
+				if line[0].Kind == token.Ident {
 					inf.mnemLen = len(line[0].Text)
 					if funcID >= 0 && inf.mnemLen > maxWidth[funcID] {
 						maxWidth[funcID] = inf.mnemLen
 					}
 				}
 			}
+		}
 		infos[i] = inf
 	}
 
@@ -83,16 +102,39 @@ func Source(src string) string {
 			out = line[0].Text + " " + renderOps(line[1:])
 			inBody = line[0].Text == "TEXT"
 		case kLabel:
-			out = line[0].Text + ":"
+			// Every label, and a trailing instruction, becomes its own
-			// A label may share its line with an instruction; emit the
+			// output line: separate outLines keep the blank-line pass
-			// instruction on the following line.
+			// honest about what it is looking at.
-			if rest := line[2:]; len(rest) > 0 {
+			outs = append(outs, outLine{kind: kLabel, text: line[0].Text + ":"})
-				out += "\n" + renderInstr(rest, maxWidth[inf.funcID])
+			rest := line[2:]
+			for len(rest) >= 2 && rest[0].Kind == token.Ident && rest[1].Kind == token.Colon &&
+				!isDirective(rest[0].Text) {
+				outs = append(outs, outLine{kind: kLabel, text: rest[0].Text + ":"})
+				rest = rest[2:]
 			}
+			// A label may share its line with an instruction; the canonical
+			// form puts the instruction on the following line.  Trailing
+			// content that does not start an instruction (a stray operand
+			// token) stays on the label line: splitting it off would produce
+			// a line the parser rejects.
+			if len(rest) > 0 && rest[0].Kind == token.Ident && isDirective(rest[0].Text) {
+				// A bare directive cannot start a line of its own (the
+				// parser wants a symbol per line), so a directive sharing
+				// the label's line stays there.
+				outs[len(outs)-1].text += " " + strings.TrimRight(renderOps(rest), " \t")
+			} else if len(rest) > 0 && rest[0].Kind == token.Ident {
+				outs = append(outs, outLine{kind: kInstr, text: strings.TrimRight(renderInstr(rest, maxWidth[inf.funcID]), " \t")})
+				if strings.EqualFold(rest[0].Text, "RET") {
+					inBody = false
+				}
+			} else if len(rest) > 0 {
+				outs[len(outs)-1].text += " " + renderOps(rest)
+			}
+			continue
 		case kInstr:
 			out = renderInstr(line, maxWidth[inf.funcID])
 			// A RET ends the body for indentation purposes: comments that
-			// follow it — typically the next function's doc comment — belong
+			// follow it, typically the next function's doc comment, belong
 			// at column 0, not inside the finished function.
 			if strings.EqualFold(line[0].Text, "RET") {
 				inBody = false
@@ -120,8 +162,8 @@ type outLine struct {
 }
 
 // normalizeSpacing enforces the canonical blank-line layout: runs of blank
-// lines collapse to one, and a new block — a label, or a TEXT or GLOBL
+// lines collapse to one, and a new block, a label, or a TEXT or GLOBL
-// directive — is preceded by exactly one blank line.  Comments immediately
+// directive, is preceded by exactly one blank line.  Comments immediately
 // above a block belong to it, so the blank line is inserted before them.  No
 // blank line is forced at the top of the file, right after a TEXT (the
 // function's first label), or between stacked labels that share an address.
@@ -192,6 +234,13 @@ func renderInstr(line []token.Token, width int) string {
 	if ops == "" {
 		return "\t" + mnem
 	}
+	// Alignment is a mnemonic convention: a line that does not start with
+	// an identifier (a stray operand token the parser tolerates) renders
+	// unpadded, so that no alignment width can depend on it and the output
+	// stays stable across passes.
+	if line[0].Kind != token.Ident {
+		return "\t" + mnem + " " + ops
+	}
 	if width < len(mnem) {
 		width = len(mnem)
 	}
@@ -217,7 +266,19 @@ func renderPreproc(line []token.Token) string {
 func renderOps(toks []token.Token) string {
 	var b strings.Builder
 	for i, t := range toks {
-		if i > 0 && spaceBetween(toks[i-1], t) {
+		sp := i > 0 && spaceBetween(toks[i-1], t)
+		// The accumulated text ending in '/' must never meet a '/' or '*':
+		// the pair would re-lex as a comment and the next pass would see a
+		// different line, whatever the token boundaries were.
+		if !sp && i > 0 && (t.Kind == token.Slash || t.Kind == token.Star) && strings.HasSuffix(b.String(), "/") {
+			sp = true
+		}
+		if sp {
+			b.WriteByte(' ')
+		} else if i > 0 && wouldMerge(toks[i-1], t) {
+			// The tight spelling would re-lex as something else ('/'
+			// before '*' opens a comment), which would make the next
+			// formatting pass see a different line.
 			b.WriteByte(' ')
 		}
 		b.WriteString(t.Text)
@@ -225,8 +286,27 @@ func renderOps(toks []token.Token) string {
 	return b.String()
 }
 
+// wouldMerge reports whether writing prev immediately before cur would
+// re-lex as something other than those two tokens: a '/' before a '*' opens
+// a comment, '>' before '>' shifts, and adjacent operators regroup.
+func wouldMerge(prev, cur token.Token) bool {
+	var kinds []token.Kind
+	for _, t := range lexer.Tokenize(prev.Text + cur.Text) {
+		if t.Kind == token.EOF {
+			break
+		}
+		kinds = append(kinds, t.Kind)
+	}
+	return len(kinds) != 2 || kinds[0] != prev.Kind || kinds[1] != cur.Kind
+}
+
 // spaceBetween decides whether a single space separates prev and cur.
 func spaceBetween(prev, cur token.Token) bool {
+	// '/' beside '/' or '*' would form a comment opener in the output and
+	// make the next pass see a different line; keep them separated.
+	if prev.Kind == token.Slash && (cur.Kind == token.Slash || cur.Kind == token.Star) {
+		return true
+	}
 	switch cur.Kind {
 	case token.RParen:
 		return false
@@ -274,6 +354,13 @@ func splitLines(toks []token.Token) [][]token.Token {
 		if t.Kind == token.EOF {
 			break
 		}
+		if t.Kind == token.Illegal {
+			// Illegal tokens carry no canonical spelling: the parser
+			// reports them as errors where they matter, and the formatter
+			// drops them so that a stray character cannot survive into the
+			// output and make the next pass render a different file.
+			continue
+		}
 		if t.Kind == token.Newline {
 			lines = append(lines, cur)
 			cur = nil

format/format_test.go

@@ -39,7 +39,7 @@ func TestGolden(t *testing.T) {
 }
 
 // TestDocCommentIndent checks that a doc comment preceding a TEXT directive
-// sits at column 0 even when another function (ending in RET) precedes it —
+// sits at column 0 even when another function (ending in RET) precedes it;
 // the RET must terminate the previous body for indentation purposes.
 func TestDocCommentIndent(t *testing.T) {
 	in := "#include \"textflag.h\"\n" +

format/fuzz_test.go

@@ -0,0 +1,47 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+package format
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"sourcedock.dev/petrbalvin/gasm-devkit/parser"
+)
+
+// FuzzFormatIdempotency hammers the formatter with arbitrary input.  The
+// contract: formatting twice equals formatting once, and input that parses
+// cleanly still parses cleanly after formatting.  The seed corpus carries the
+// repository's kernels, so a plain `go test` run replays every seed as a
+// regression case and CI exercises them without any fuzzing budget.
+func FuzzFormatIdempotency(f *testing.F) {
+	for _, pattern := range []string{
+		"../testdata/*.s",
+		"../testdata/verify/*.s",
+	} {
+		files, _ := filepath.Glob(pattern)
+		for _, path := range files {
+			if b, err := os.ReadFile(path); err == nil {
+				f.Add(string(b))
+			}
+		}
+	}
+	f.Add("TEXT ·f(SB), NOSPLIT, $0\n\tMOVQ AX, BX\n\tRET\n")
+	f.Add("TEXT ·f(SB),NOSPLIT,$0\n\tMOVQ   AX,BX\n\n\n\tRET\n")
+	f.Add("garbage ### ???\n")
+
+	f.Fuzz(func(t *testing.T, src string) {
+		once := Source(src)
+		twice := Source(once)
+		if once != twice {
+			t.Fatalf("formatting is not idempotent:\nfirst:  %q\nsecond: %q", once, twice)
+		}
+		if _, errs := parser.Parse("in.s", src); len(errs) == 0 {
+			if _, errs := parser.Parse("out.s", once); len(errs) > 0 {
+				t.Fatalf("formatted output of clean input does not parse: %v\n%s", errs[0], once)
+			}
+		}
+	})
+}

format/testdata/fuzz/FuzzFormatIdempotency/137e971b6c85c550

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("0:A:")

format/testdata/fuzz/FuzzFormatIdempotency/17b855695dea8604

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("$0/ *")

format/testdata/fuzz/FuzzFormatIdempotency/33f8a656ea629ef1

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("A:TEXT")

format/testdata/fuzz/FuzzFormatIdempotency/411fa81747cc1665

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("TEXT\n0:A:A0\nA 0")

format/testdata/fuzz/FuzzFormatIdempotency/6347729745559df8

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("00/ /*")