feat(cmd): GOOS-aware headers, audit battery shapes and semicolon spacing

Assisted-by: GLM 5.3 Flash

cmd/gasm/audit.go

@@ -5,6 +5,7 @@ package main
 
 import (
 	"fmt"
+	"maps"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -288,6 +289,11 @@ func probeShapes(a arch.Arch) []string {
 			"V1.B16, [V2.B16], V3.B16", "V1.B8, [V2.B16, V3.B16], V4.B8",
 			"$4, V1.B16, V2.B16, V3.B16", "$15, V1", "V1, V2, p2",
 			"R0, R1, $1, $4, p2",
+			// The landing-pad kind, the compiler's PCDATA
+			// bookkeeping and the four-operand bitfield
+			// insert/extract family, as the toolchain's own
+			// testdata spells them.
+			"C", "$1, $0", "$0, R1, $1, R2",
 		}
 	case arch.RISCV:
 		return []string{
@@ -307,6 +313,9 @@ func probeShapes(a arch.Arch) []string {
 			"X5, X6, p2", "R5, R6, p2",
 			"X5, E8, M8, TA, MA, X6", "$4, E32, M1, TA, MA, X1",
 			"(X5), X6, V1, V2",
+			// The CSR immediate forms the toolchain's testdata spells:
+			// immediate, CSR name, destination.
+			"$2, TIME, X5",
 			"",
 		}
 	case arch.LOONG64:
@@ -323,6 +332,12 @@ func probeShapes(a arch.Arch) []string {
 			"V1, V2, V3", "X1, X2, X3", "V1, V2", "X1, X2", "V1", "X1",
 			// The vector compare-to-flag forms land in an FCC register.
 			"V1, FCC0", "X1, FCC0",
+			// The compiler's bookkeeping pair and the raw spellings the
+			// toolchain's own testdata carries: JIRL rd, rj, offset (the
+			// form RET lowers to), the prefetch with a 32-bit address and
+			// hint, and the byte-shuffle quads.
+			"$1, $0", "R1, R5, 0", "0(R7), $5, $0", "(R7), $5, $0",
+			"V1, V2, V3, V4", "X1, X2, X3, X4",
 			"",
 		}
 	}
@@ -487,10 +502,47 @@ func otherPortFile(path string) bool {
 
 // goOSNames are the GOOS values go/build recognises in file names.
 var goOSNames = map[string]bool{
-	"aix": true, "darwin": true, "dragonfly": true, "freebsd": true,
-	"ios": true, "js": true, "linux": true, "netbsd": true,
+	"aix": true, "android": true, "darwin": true, "dragonfly": true,
+	"freebsd": true, "hurd": true, "illumos": true, "ios": true,
+	"js": true, "linux": true, "nacl": true, "netbsd": true,
 	"openbsd": true, "plan9": true, "solaris": true, "wasip1": true,
-	"windows": true,
+	"windows": true, "zos": true,
+}
+
+// resolveGOOS validates a -GOOS flag value, mirroring the architecture
+// check's surface: a usage error naming what the tool accepts.
+func resolveGOOS(name string) (string, error) {
+	lower := strings.ToLower(name)
+	if goOSNames[lower] {
+		return lower, nil
+	}
+	return "", &usageError{fmt.Errorf("unknown GOOS %q: want one of %s", name, strings.Join(slices.Sorted(maps.Keys(goOSNames)), ", "))}
+}
+
+// goosFromFilename returns the GOOS the file's name carries, by go/build's
+// goodOSArchFile rule: the GOOS segment sits last, or last before the
+// architecture segment (sys_darwin_arm64.s, vlop_arm.s carries none).  An
+// empty result means the name names no GOOS and the ambient one applies.
+func goosFromFilename(path string) string {
+	base := path
+	if i := strings.LastIndexByte(base, '/'); i >= 0 {
+		base = base[i+1:]
+	}
+	base = strings.TrimSuffix(base, ".s")
+	// go/build ignores everything before the first underscore, so a GOOS
+	// segment is only ever looked for from there on.
+	i := strings.IndexByte(base, '_')
+	if i < 0 {
+		return ""
+	}
+	segs := strings.Split(base[i:], "_")
+	if n := len(segs); n >= 2 && goOSNames[segs[n-2]] && slices.Contains(goPortSuffixes, segs[n-1]) {
+		return segs[n-2]
+	}
+	if goOSNames[segs[len(segs)-1]] {
+		return segs[len(segs)-1]
+	}
+	return ""
 }
 
 // otherGOOSFile reports whether the file's name names a GOOS other than the
@@ -543,6 +595,12 @@ func runCorpusAudit(root string, dirs includeDirs) (*corpusStats, error) {
 			return nil, err
 		}
 
+		// The GOOS the header generation type-checks under follows the
+		// file's name when the name carries one; the ambient GOOS is the
+		// honest guess otherwise (a build tag naming another GOOS is
+		// invisible to a file-name rule).
+		goos := goosFromFilename(path)
+
 		var wanted []int // indexes into targets
 		if a := arch.FromFilename(path); a != arch.Unknown {
 			for i, tg := range targets {
@@ -567,11 +625,12 @@ func runCorpusAudit(root string, dirs includeDirs) (*corpusStats, error) {
 
 		// A file that includes go_asm.h parses against a per-target header:
 		// the defines differ per architecture (internal/cpu's layout, for
-		// one), so the parse cannot be shared the way a header-free file's
-		// can.  A generation failure is a failure for every target, named
-		// for the package rather than a bare "include not found".  A header
-		// already resolvable in the package directory or the -I list is
-		// left alone.
+		// one) and per GOOS (sys_darwin_arm64.s's trampoline constants,
+		// for another), so the parse cannot be shared the way a
+		// header-free file's can.  A generation failure is a failure for
+		// every target, named for the package rather than a bare "include
+		// not found".  A header already resolvable in the package
+		// directory or the -I list is left alone.
 		if len(wanted) > 0 && needsGoAsmHeader(src) && !goAsmHeaderResolved(filepath.Dir(path), dirs) {
 			if hdr == nil {
 				if hdr, err = newAsmhdrCache(); err != nil {
@@ -583,7 +642,7 @@ func runCorpusAudit(root string, dirs includeDirs) (*corpusStats, error) {
 			for _, i := range wanted {
 				tg, t := targets[i], tallies[i]
 				t.attempted++
-				hdrDir, err := hdr.dirFor(pkgDir, goarchName(tg.a))
+				hdrDir, err := hdr.dirFor(pkgDir, goos, goarchName(tg.a))
 				if err != nil {
 					ok = false
 					t.fail(path, corpusReason(err))