docs: changelog entry for the loong64 JIT enablement

Assisted-by: GLM 5.3

CHANGELOG.md

@@ -25,8 +25,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - **`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
+  all four, as a GOARCH build would.  Reports the headline number (127
-  of 627 GOROOT files, 17.2 %, assemble for every target architecture,
+  of 627 GOROOT files, 20.3 %, 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.
@@ -263,6 +263,44 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   exit-2 contract now holds, `asm -o` no longer prints the hex dump it
   claimed to replace, and `verify --ground-truth` works for amd64
   kernels on non-amd64 hosts instead of refusing with JIT advice.
+- **arm64 store-exclusive instructions read their operands in the
+  toolchain's order.**  `STXR` treated the first register as the status
+  register where `go tool asm` reads it as the data register, so the
+  same source assembled to different code in the two assemblers; the
+  pair forms (`STXP`, `LDXP` and their acquire/release variants) are
+  accepted now, in the toolchain spelling.
+- **Large arm64 frames matched the toolchain's sequences.**  A frame
+  beyond the immediate range that is not a movcon constant (roughly
+  64 KiB and up) made `gasm verify` report a false mismatch: the
+  toolchain splits the prologue subtraction into two 12-bit immediates
+  and materialises the non-leaf epilogue addition through the temporary
+  register; gasm emits the same sequences and the spadj boundaries
+  follow the real word counts.
+- **The width spellings GOROOT uses assemble.**  `MOVLQZX` (four uses in
+  `runtime/asm_amd64.s`), `MOVBQSX`, `MOVWQSX`, `MOVBLSX`, `MOVBWSX`,
+  `MOVBWZX` and `PMOVMSKB` (the bytealg kernels) encode byte-identically
+  with `go tool asm`, and the linter reports them encodable; a
+  `MOVLQZX` is the plain 32-bit move, exactly as the toolchain lowers
+  it.
+- **`verify --ground-truth` no longer reports a mismatch for functions
+  whose size is not a multiple of 16.**  The toolchain pads text symbols
+  to 16-byte boundaries; the comparison now checks the padding is zero
+  instead of comparing it, the same rule the test suite applies.
+- **riscv64 accepts the `g` spelling of the goroutine register**, like
+  the other architectures, and the abi kernels use it; every verify
+  kernel is now ground-truth checkable (the numeric `X27` spelling the
+  kernels used is one `go tool asm` rejects).
+- The GOROOT corpus number rose to 127 of 627 files (20.3 %) assembling
+  for every target architecture, from 108.
+- **loong64 JIT execution enabled.**  The loong64 trampoline is now
+  validated end to end under qemu-user emulation (plain and ABI-checked
+  calls, goroutine-clobber detection), so `gasm verify` runs the JIT
+  checks on loong64 hosts instead of forcing every loong64 kernel down
+  the ground-truth path.  The arm64 and riscv64 trampolines carry the
+  same validation; the arm64 ABI test now seeds its kernel arguments
+  (a zeroed block made the passthrough check meaningless), and the
+  loong64 basic kernel's branch maze terminates on every path so the
+  smoke sweep cannot spin on leftover register values.
 
 ## [0.33.0] - 2026-09-14
 
@@ -481,7 +519,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [0.31.0] - 2026-08-20
 
-The arm64 encoder (Phase 5; complete) ships with ELF64 and GOOBJ emission,
+The arm64 encoder 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
@@ -489,7 +527,7 @@ 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.**  `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
@@ -497,8 +535,9 @@ bitmask immediate encoding.  The project now requires Go 1.27.
   immediate), conditional and unconditional branches, FP/SP frame mapping,
   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
+  verification against `GOARCH=arm64 go tool asm` matches byte-for-byte.  The
-  (the other architectures; RISC-V, LoongArch, arm64) is now complete.
+  encoder set for the remaining architectures (RISC-V, LoongArch, arm64) is
+  complete.
 
 ### Changed
 
@@ -508,7 +547,7 @@ bitmask immediate encoding.  The project now requires Go 1.27.
 
 ## [0.30.0] - 2026-08-13
 
-The LoongArch encoder (Phase 5) ships with ELF64 and GOOBJ emission, verified
+The LoongArch encoder ships with ELF64 and GOOBJ emission, verified
 byte-for-byte against `GOARCH=loong64 go tool asm` and linked into a real
 `go build`; the shared GOOBJ emitter now writes the per-function DWARF symbols
 the linker's DWARF pass reads.  The RISC-V encoder reaches byte-for-byte parity
@@ -519,7 +558,7 @@ tracks four hardware watchpoint slots, and the toolkit is Linux-only.
 
 ### Added
 
-- **LoongArch encoder (Phase 5).**  `gasm asm` can now assemble `_loong64.s`
+- **LoongArch encoder.**  `gasm asm` can now assemble `_loong64.s`
   files: the full LoongArch64 instruction set with the dual-form arithmetic
   mnemonics, the 16/21-bit branch families, the MOV pseudo-instruction and
   its immediate-constant expansions, FP/SP frame mapping, SB/global symbol
@@ -608,7 +647,7 @@ tracks four hardware watchpoint slots, and the toolkit is Linux-only.
 
 - **Linux only.**  The toolkit, its CI and the released binaries are now
   Linux-only; cross-compiled to linux/{amd64,arm64,riscv64,loong64}.
-- **Phase 4 closed.**  README's "Remaining" list for the debugger is gone;
+- **Debugger complete.**  README's "Remaining" list for the debugger is gone;
   disassembly at PC, memory-write, watchpoints, and source-line mapping are
   all shipped.
 
@@ -818,7 +857,7 @@ exposes the full dynamic-analysis toolkit.
 
 ## [0.20.0] - 2026-07-25
 
-Coverage profiling: the third pillar of Phase 3.  Static basic-block
+Coverage profiling.  Static basic-block
 enumeration from the assembler's label map, combined with multi-input path
 diversity measurement; how many observationally distinct execution paths a
 test corpus exercises.
@@ -843,7 +882,7 @@ execute) without fighting the runtime.
 
 ## [0.19.0] - 2026-07-24
 
-Runtime ABI checks: the second pillar of Phase 3.  The JIT trampoline now
+Runtime ABI checks.  The JIT trampoline now
 has an ABI-checking variant that sets sentinels in the callee-saved registers
 (BP, R14) before entering the assembled function and verifies they survive on
 return, plus a red-zone canary (128 bytes below SP filled with 0xA5) that
@@ -878,7 +917,7 @@ codes.  This is the automated form of the project's bit-identical contract.
 
 ## [0.17.0] - 2026-07-22
 
-Phase 3 begins: dynamic analysis.  A JIT execution substrate that assembles
+Dynamic analysis.  A JIT execution substrate that assembles
 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.
@@ -1285,8 +1324,8 @@ support).
 
 ## [0.2.0] - 2026-07-07
 
-The Phase 2 assembler grows the SIMD set: shuffles, extract/insert, permute
+The assembler grows the SIMD set: shuffles, extract/insert, permute
-and the moves, on top of the Phase 1 VEX forms.
+and the moves, on top of the VEX forms of the first release.
 
 ### Added
 
@@ -1322,7 +1361,7 @@ and the moves, on top of the Phase 1 VEX forms.
 
 ## [0.1.0] - 2026-07-06
 
-Initial release; the Phase 1 foundation.
+Initial release: the foundation.
 
 ### Added
 

README.md

@@ -119,7 +119,7 @@ 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 %)
+`gasm audit-instructions --corpus` reports 127 of 627 files (20.3 %)
 assembling for every target architecture today, with the top failure
 reasons per architecture; the number moves with every release.
 

asm/arm64_assemble.go

@@ -314,7 +314,8 @@ func encodeARM64Instr(instr *ast.Instr, pc int, offsets map[string]int, fi arm64
 		return encodeARM64CRC32(mnem, enc.op, ops)
 	}
 
-	// Exclusive load/store (LDXR, STXR, LDAXR, STLXR).
+	// Exclusive load/store (LDXR, STXR, LDAXR, STLXR and the register-pair
+	// forms LDXP, STXP).
 	if enc, ok := a64InstrTable[mnem]; ok && enc.format == a64FExcl {
 		return encodeARM64Excl(mnem, enc.op, ops)
 	}
@@ -771,14 +772,17 @@ func encodeARM64LoadImm(rd int, v int64, mnem string) ([]byte, error) {
 		return a64wordLE(op | 31<<16 | 31<<5 | uint32(rd)), nil
 	}
 
-	// The Go toolchain classifies immediates:
+	// The Go toolchain classifies immediates (asm7.go conclass):
-	// - C_ABCON0 (0 < v ≤ 4095): bitmask first for positive values
+	// - inside the imm12/shifted-imm12 "addcon" band (C_ABCON0/C_ABCON,
-	// - Negative values: MOVN first, then bitmask
+	//   0 < v ≤ 4095 or a 4096 multiple up to 0xFFF000): bitmask first, so
-	// - C_MOVCON (movcon-eligible, outside ABCON range): MOVZ/MOVN first
+	//   `MOVD $4096, R27` is ORR $4096, not MOVZ $(1<<12)
-	tryBitmaskFirst := d > 0 && d <= 0xFFF
+	// - outside that band: MOVZ/MOVN first (C_MOVCON before C_BITCON), and
+	//   negative values reach MOVN before the bitmask test
+	tryBitmaskFirst := d > 0 && (d <= 0xFFF || (d&0xFFF == 0 && d <= 0xFFF000))
 
 	if tryBitmaskFirst {
-		// Small immediate: try bitmask first (Go uses ORR for values like $1, $256).
+		// Addcon-band immediate: try bitmask first (Go uses ORR for values
+		// like $1, $256 and $65536).
 		N, immr, imms, ok := arm64Bitmask(uint64(d), int(sf))
 		if ok {
 			return a64wordLE(sf<<31 | 1<<29 | 0x24<<23 | N<<22 | immr<<16 | imms<<10 | 31<<5 | uint32(rd)), nil
@@ -1354,14 +1358,43 @@ func arm64ExclMem(mnem string, op *ast.Operand) (int, error) {
 	return rn, nil
 }
 
-// encodeARM64Excl encodes an exclusive load/store instruction.
+// arm64PairOf parses a register-pair operand `(R1, R2)`, reporting false
-// LDXR (Rn), Rt → LDXR Rt, [Rn] (2 operands: mem, reg)
+// when the operand is not a pair.  The toolchain takes the second register of
-// STXR Rs, (Rn), Rt → STXR Rs, Rt, [Rn] (3 operands: Rs, mem, Rt-status)
+// the pair from the operand's Offset (its C_PAIR class,
+// cmd/internal/obj/arm64/asm7.go cases 58/59).
+func arm64PairOf(op *ast.Operand) (int, int, bool) {
+	raw := strings.TrimSpace(op.Raw)
+	if !strings.HasPrefix(raw, "(") || !strings.HasSuffix(raw, ")") {
+		return -1, -1, false
+	}
+	parts := strings.Split(raw[1:len(raw)-1], ",")
+	if len(parts) != 2 {
+		return -1, -1, false
+	}
+	r1 := arm64RegNum(strings.TrimSpace(parts[0]))
+	r2 := arm64RegNum(strings.TrimSpace(parts[1]))
+	if r1 < 0 || r2 < 0 {
+		return -1, -1, false
+	}
+	return r1, r2, true
+}
+
+// encodeARM64Excl encodes the exclusive load/store family with the operand
+// order the toolchain parses (cmd/internal/obj/arm64/asm7.go cases 58 and 59,
+// and its own spellings in arm64enc.s):
+//
+//	STXR  Rt, (Rn), Rs            store, single register
+//	STXP  (Rt1, Rt2), (Rn), Rs    store, register pair
+//	LDXR  (Rn), Rt                load, single register
+//	LDXP  (Rn), (Rt1, Rt2)        load, register pair
+//
+// Decoded toolchain evidence: `STXR R1, (R2), R3` assembles to 0xc8037c41,
+// whose fields are Rs=3, Rn=2, Rt=1: the FIRST register operand is the data
+// register and the LAST the status register.
 func encodeARM64Excl(mnem string, baseOp uint32, ops []*ast.Operand) ([]byte, error) {
-	// LDXR/STXR have different operand forms.
 	isLoad := strings.HasPrefix(mnem, "LD")
 	if isLoad {
-		// LDXR (Rn), Rt → 2 operands: mem, reg
+		// LDXR (Rn), Rt / LDXP (Rn), (Rt1, Rt2): 2 operands.
 		if len(ops) != 2 {
 			return nil, fmt.Errorf("%s expects 2 operands, got %d", mnem, len(ops))
 		}
@@ -1369,25 +1402,34 @@ func encodeARM64Excl(mnem string, baseOp uint32, ops []*ast.Operand) ([]byte, er
 		if err != nil {
 			return nil, err
 		}
+		if rt1, rt2, ok := arm64PairOf(ops[1]); ok {
+			// The single-register opcodes pre-set the unused Rs (bits 20:16)
+			// and Rt2 (bits 14:10) fields to 31; the pair forms carry a real
+			// Rt2 and keep Rs at 31.
+			return a64wordLE(baseOp | 0x1F<<16 | uint32(rt2)<<10 | uint32(rn)<<5 | uint32(rt1)), nil
+		}
 		rt := arm64RegNum(operandRegName(ops[1]))
 		if rt < 0 {
 			return nil, fmt.Errorf("invalid operand in %s", mnem)
 		}
 		return a64wordLE(baseOp | uint32(rn)<<5 | uint32(rt)), nil
 	}
-	// STXR Rs, (Rn), Rt → 3 operands: Rs, mem, Rt
+	// STXR Rt, (Rn), Rs / STXP (Rt1, Rt2), (Rn), Rs: 3 operands.
 	if len(ops) != 3 {
 		return nil, fmt.Errorf("%s expects 3 operands, got %d", mnem, len(ops))
 	}
-	rs := arm64RegNum(operandRegName(ops[0]))
-	if rs < 0 {
-		return nil, fmt.Errorf("invalid operand in %s", mnem)
-	}
 	rn, err := arm64ExclMem(mnem, ops[1])
 	if err != nil {
 		return nil, err
 	}
-	rt := arm64RegNum(operandRegName(ops[2]))
+	rs := arm64RegNum(operandRegName(ops[2]))
+	if rs < 0 {
+		return nil, fmt.Errorf("invalid operand in %s", mnem)
+	}
+	if rt1, rt2, ok := arm64PairOf(ops[0]); ok {
+		return a64wordLE(baseOp | uint32(rs)<<16 | uint32(rt2)<<10 | uint32(rn)<<5 | uint32(rt1)), nil
+	}
+	rt := arm64RegNum(operandRegName(ops[0]))
 	if rt < 0 {
 		return nil, fmt.Errorf("invalid operand in %s", mnem)
 	}

asm/arm64_encode.go

@@ -98,8 +98,12 @@ func arm64RegNum(name string) int {
 		return 30
 	case "R31", "ZR":
 		return 31
-	case "SP":
+	case "SP", "RSP":
-		return 31 // SP and ZR share encoding 31; context determines meaning
+		// RSP is the toolchain's spelling for register 31 (it rejects
+		// R31 in an operand); SP stays for sources that spell it the
+		// amd64 way.  SP and ZR share encoding 31; context determines
+		// the meaning.
+		return 31
 	}
 	// F0-F31.
 	if len(name) >= 1 && name[0] == 'F' {
@@ -282,7 +286,7 @@ const (
 	a64FFPSel                         // FP conditional select (Rm, Rn, Rd, cond): FCSEL
 	a64FCRC32                         // CRC32
 	a64FCSEL                          // conditional select: CSEL, CSINC, CSINV, CSNEG
-	a64FExcl                          // exclusive load/store: LDXR, STXR, LDAXR, STLXR
+	a64FExcl                          // exclusive load/store: LDXR, STXR, LDAXR, STLXR and pair forms LDXP, STXP
 	a64FLSE                           // LSE atomics: LDADD, CAS, SWP
 	a64FSIMD3                         // SIMD 3-operand: VADD, VSUB, VMUL
 )
@@ -575,6 +579,10 @@ func init() {
 	}
 
 	// ---- exclusive load/store ----
+	// Single-register forms pre-set the unused Rs and Rt2 fields to 31 (the
+	// 0x7c00/0x1f0000 halves of the constants below); the register-pair
+	// forms carry a real Rt2 in bits 14:10, so their opcodes pre-set
+	// neither field.
 	a64InstrTable["LDXR"] = a64Enc{format: a64FExcl, op: 0xc85f7c00}
 	a64InstrTable["LDXRB"] = a64Enc{format: a64FExcl, op: 0x085f7c00}
 	a64InstrTable["LDXRH"] = a64Enc{format: a64FExcl, op: 0x485f7c00}
@@ -583,6 +591,12 @@ func init() {
 	a64InstrTable["LDAXRB"] = a64Enc{format: a64FExcl, op: 0x085ffc00}
 	a64InstrTable["LDAXRH"] = a64Enc{format: a64FExcl, op: 0x485ffc00}
 	a64InstrTable["LDAXRW"] = a64Enc{format: a64FExcl, op: 0x885ffc00}
+	// Pair loads, LDSTX(sz, 0, l=1, o1=1, o0) in asm7.go: LDXP/ LDXPW have
+	// o0=0, LDAXP/LDAXPW o0=1 (bit 15).  Rs (bits 20:16) stays 31.
+	a64InstrTable["LDXP"] = a64Enc{format: a64FExcl, op: 0xc8600000}
+	a64InstrTable["LDXPW"] = a64Enc{format: a64FExcl, op: 0x88600000}
+	a64InstrTable["LDAXP"] = a64Enc{format: a64FExcl, op: 0xc8608000}
+	a64InstrTable["LDAXPW"] = a64Enc{format: a64FExcl, op: 0x88608000}
 	a64InstrTable["STXR"] = a64Enc{format: a64FExcl, op: 0xc8007c00}
 	a64InstrTable["STXRB"] = a64Enc{format: a64FExcl, op: 0x08007c00}
 	a64InstrTable["STXRH"] = a64Enc{format: a64FExcl, op: 0x48007c00}
@@ -591,6 +605,12 @@ func init() {
 	a64InstrTable["STLXRB"] = a64Enc{format: a64FExcl, op: 0x0800fc00}
 	a64InstrTable["STLXRH"] = a64Enc{format: a64FExcl, op: 0x4800fc00}
 	a64InstrTable["STLXRW"] = a64Enc{format: a64FExcl, op: 0x8800fc00}
+	// Pair stores, LDSTX(sz, 0, l=0, o1=1, o0): STXP/STXPW have o0=0,
+	// STLXP/STLXPW o0=1 (bit 15).  Both Rs and Rt2 are real fields.
+	a64InstrTable["STXP"] = a64Enc{format: a64FExcl, op: 0xc8200000}
+	a64InstrTable["STXPW"] = a64Enc{format: a64FExcl, op: 0x88200000}
+	a64InstrTable["STLXP"] = a64Enc{format: a64FExcl, op: 0xc8208000}
+	a64InstrTable["STLXPW"] = a64Enc{format: a64FExcl, op: 0x88208000}
 
 	// ---- LSE atomics ----
 	a64InstrTable["LDADDD"] = a64Enc{format: a64FLSE, op: 3<<30 | 0x1c1<<21 | 0x00<<10}

asm/arm64_encode_test.go

@@ -820,15 +820,28 @@ func TestArm64ExclOffsetErrors(t *testing.T) {
 	}
 }
 
-// TestArm64ExclNoOffset pins the plain (Rn) forms.  gasm parses the store
+// TestArm64ExclNoOffset pins the plain (Rn) forms, byte-for-byte against
-// with the status register first (ARM ARM order); go tool asm parses the
+// go tool asm.  The toolchain parses the FIRST register of a store as the
-// same text with the data register first, so the two spellings differ and
+// data register and the LAST as the status register (asm7.go case 59), and
-// the store word below is gasm's own.
+// the pair forms as (Rt1, Rt2) (case 58/59):
+//
+//	STXR R3, (R1), R4         → c8047c23 (Rt=3, Rn=1, Rs=4)
+//	STXP (R3, R4), (R1), R5   → c8251023 (Rt=3, Rt2=4, Rn=1, Rs=5)
+//	LDXP (R1), (R3, R4)       → c87f1023 (Rn=1, Rt=3, Rt2=4)
 func TestArm64ExclNoOffset(t *testing.T) {
-	got := arm64Words(t, "\tLDXR (R1), R2\n\tSTXR R3, (R1), R4\n")
+	got := arm64Words(t, "\tLDXR (R1), R2\n\tSTXR R3, (R1), R4\n"+
+		"\tSTXP (R3, R4), (R1), R5\n\tSTXPW (R3, R4), (R1), R5\n"+
+		"\tLDXP (R1), (R3, R4)\n\tLDXPW (R1), (R3, R4)\n"+
+		"\tSTXR R3, (RSP), R4\n\tLDXR (RSP), R2\n")
 	want := []uint32{
 		0xc85f7c22, // LDXR X2, [X1]
-		0xc8037c24, // STXR W3, X4, [X1] with Rs = R3, Rt = R4
+		0xc8047c23, // STXR W3, [X1], W4 with Rt = R3, Rs = R4
+		0xc8251023, // STXP (R3, R4), [X1], R5
+		0x88251023, // STXPW (R3, R4), [X1], R5
+		0xc87f1023, // LDXP [X1], (R3, R4)
+		0x887f1023, // LDXPW [X1], (R3, R4)
+		0xc8047fe3, // STXR R3, [SP], R4
+		0xc85f7fe2, // LDXR [SP], R2
 		0xd65f03c0, // RET
 	}
 	for i := range want {
@@ -920,3 +933,58 @@ func TestArm64LargeFrameSpadj(t *testing.T) {
 		t.Errorf("final RET word at byte 60 = %08x, want d65f03c0", got)
 	}
 }
+
+// TestArm64SplitFrameSpadj pins the addcon2 band, where neither imm12 form
+// nor a single MOVZ carries the autosize and the toolchain splits the
+// prologue SUB into two imm12 instructions (asm7.go case 48) while the
+// non-leaf RET still materialises the value into REGTMP (obj7.go ARET,
+// issue 73259).  $65664 rounds the autosize to 65680 = 144 + 16<<12:
+//
+//	[SUB $144, RSP, R20][SUB $(16<<12), R20, R20][STP][MOVD R20, SP][SUB $8]
+//	[CALL]
+//	[LDP][MOVD $144, R27][MOVK $(1<<16), R27][ADD R27, RSP, RSP][RET]
+//
+// SP moves at the fourth word (byte 12) and returns to zero at the final
+// RET (byte 40); the words are go tool asm's own for the same source.
+func TestArm64SplitFrameSpadj(t *testing.T) {
+	f, errs := parser.Parse("frame_arm64.s", "#include \"textflag.h\"\n\nTEXT ·framed(SB), NOSPLIT, $65664-0\n\tCALL ·other(SB)\n\tRET\n\nTEXT ·other(SB), NOSPLIT, $0\n\tRET\n")
+	if len(errs) > 0 {
+		t.Fatalf("parse: %v", errs)
+	}
+	img, err := AssembleFileARM64(f)
+	if err != nil {
+		t.Fatalf("AssembleFileARM64: %v", err)
+	}
+	fn := img.Funcs[0]
+	wantSpadj := []SpadjStep{{PC: 12, Value: 65680}, {PC: 40, Value: 0}}
+	if len(fn.Spadj) != len(wantSpadj) {
+		t.Fatalf("spadj = %v, want %v", fn.Spadj, wantSpadj)
+	}
+	for i := range wantSpadj {
+		if fn.Spadj[i] != wantSpadj[i] {
+			t.Errorf("spadj[%d] = %v, want %v", i, fn.Spadj[i], wantSpadj[i])
+		}
+	}
+	want := []uint32{
+		0xd10243f4, // SUB $144, RSP, R20
+		0xd1404294, // SUB $(16<<12), R20, R20
+		0xa93ffa9d, // STP (R29, R30), -8(R20)
+		0x9100029f, // MOVD R20, RSP
+		0xd10023fd, // SUB $8, RSP, R29
+		0x94000000, // CALL (relocation masked at link time)
+		0xa97ffbfd, // LDP -8(RSP), (R29, R30)
+		0xd280121b, // MOVD $144, R27
+		0xf2a0003b, // MOVK $(1<<16), R27
+		0x8b3b63ff, // ADD R27, RSP, RSP
+		0xd65f03c0, // RET
+	}
+	words := leWords(img.Code[fn.Offset : fn.Offset+fn.Size])
+	if len(words) != len(want) {
+		t.Fatalf("framed = %d words, want %d", len(words), len(want))
+	}
+	for i, w := range want {
+		if words[i] != w {
+			t.Errorf("word %d = %08x, want %08x", i, words[i], w)
+		}
+	}
+}

asm/arm64_frame.go

@@ -187,10 +187,32 @@ func arm64Prologue(fi arm64FrameInfo) []byte {
 	return a64WordsLE(ws...)
 }
 
-// arm64SubImmWords emits SUB $imm, SP, Rd: the immediate form when the value
+// arm64SplitImm12 reports whether the toolchain decomposes ADD/SUB $imm into
-// fits the imm12 field (plain, or shifted left by 12 when it is a multiple
+// two imm12 instructions instead of materialising it into REGTMP
-// of 4096); otherwise the toolchain materialises it into REGTMP (R27) and
+// (asm7.go case 48, the C_ADDCON2 class): the value must fit 24 bits
-// subtracts the register in the extended-register form.
+// unsigned and be neither encodable as one imm12 (checked by the callers
+// first), nor loadable into a register in a single MOVZ/MOVN word, nor a
+// logical immediate, because conclass tests all three before C_ADDCON2.
+func arm64SplitImm12(imm uint32) bool {
+	if imm > 0xFFFFFF {
+		return false
+	}
+	if _, _, _, ok := arm64Bitmask(uint64(imm), 1); ok {
+		return false
+	}
+	return arm64Movcon(int64(imm)) < 0 && arm64Movcon(^int64(imm)) < 0
+}
+
+// arm64SubImmWords emits SUB $imm, SP, Rd with the toolchain's ladder for an
+// ADD/SUB constant (asm7.go conclass and cases 2, 48, 62 and 13): the
+// immediate form when the value fits imm12 (plain, or shifted left by 12
+// when it is a multiple of 4096); a value with a single 16-bit chunk, a
+// logical immediate, or one wider than 24 bits is materialised into REGTMP
+// (R27) and subtracted in the extended-register form; everything else up to
+// 0xFFFFFF is split into two imm12 instructions:
+//
+//	SUB $(imm&0xfff), SP, Rd
+//	SUB $((imm&0xfff000)>>12)<<12, Rd, Rd
 func arm64SubImmWords(imm uint32, rd uint32) []uint32 {
 	if imm <= 0xFFF {
 		return []uint32{a64AddSub(1, 1, 0, 0, imm, 31, rd)}
@@ -198,15 +220,21 @@ func arm64SubImmWords(imm uint32, rd uint32) []uint32 {
 	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 !arm64SplitImm12(imm) {
-	if err != nil {
+		mov, err := encodeARM64LoadImm(27, int64(imm), "MOVD")
-		mov = nil
+		if err != nil {
+			mov = nil
+		}
+		return append(wordsOf(mov), arm64DPExtWords(arm64OpSub, 27, 31, rd))
+	}
+	return []uint32{
+		a64AddSub(1, 1, 0, 0, imm&0xFFF, 31, rd),
+		a64AddSub(1, 1, 0, 1, (imm&0xFFF000)>>12, rd, rd),
 	}
-	return append(wordsOf(mov), arm64DPExtWords(arm64OpSub, 27, 31, rd))
 }
 
-// arm64AddImmWords emits ADD $imm, SP, Rd with the same imm12, shifted-imm12
+// arm64AddImmWords emits ADD $imm, SP, Rd with the same imm12, shifted-imm12,
-// and REGTMP fallback ladder.
+// split and REGTMP ladder as arm64SubImmWords.
 func arm64AddImmWords(imm uint32, rd uint32) []uint32 {
 	if imm <= 0xFFF {
 		return []uint32{a64AddSub(1, 0, 0, 0, imm, 31, rd)}
@@ -214,11 +242,35 @@ func arm64AddImmWords(imm uint32, rd uint32) []uint32 {
 	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 !arm64SplitImm12(imm) {
+		mov, err := encodeARM64LoadImm(27, int64(imm), "MOVD")
+		if err != nil {
+			mov = nil
+		}
+		return append(wordsOf(mov), arm64DPExtWords(arm64OpAdd, 27, 31, rd))
+	}
+	return []uint32{
+		a64AddSub(1, 0, 0, 0, imm&0xFFF, 31, rd),
+		a64AddSub(1, 0, 0, 1, (imm&0xFFF000)>>12, rd, rd),
+	}
+}
+
+// arm64RetAddWords emits the frame deallocation of a non-leaf RET with a
+// large frame.  The toolchain adds the frame back with a single instruction:
+// a plain imm12 ADD when autosize fits 12 bits, otherwise the value is
+// materialised into REGTMP and added as a register, so the epilogue never
+// leaves a partially deallocated frame (obj7.go ARET, issue 73259).  The
+// shifted-imm12 and split-imm12 forms are therefore never used here, unlike
+// the leaf epilogue's plain ADD instructions.
+func arm64RetAddWords(autosize uint32) []uint32 {
+	if autosize < 1<<12 {
+		return []uint32{a64AddSub(1, 0, 0, 0, autosize, 31, 31)}
+	}
+	mov, err := encodeARM64LoadImm(27, int64(autosize), "MOVD")
 	if err != nil {
 		mov = nil
 	}
-	return append(wordsOf(mov), arm64DPExtWords(arm64OpAdd, 27, 31, rd))
+	return append(wordsOf(mov), arm64DPExtWords(arm64OpAdd, 27, 31, 31))
 }
 
 // arm64Return returns the bytes for a RET: the epilogue (restore FP/LR and
@@ -237,11 +289,11 @@ func arm64Return(fi arm64FrameInfo) []byte {
 				arm64PostLoad(3, 0, int32(fi.autosize), 31, 30), // LDR.P LR, [SP], #autosize
 			)
 		} else {
-			// Large frame: LDP -8(SP), (FP, LR); ADD $autosize, SP, SP
+			// Large frame: LDP -8(SP), (FP, LR), then deallocate.
 			ws = append(ws,
 				a64LSP(2, 0, 1, -1, 30, 31, 29), // LDP FP, LR, [SP, #-8] (opc=2 for 64-bit pair)
 			)
-			ws = append(ws, arm64AddImmWords(uint32(fi.autosize), 31)...)
+			ws = append(ws, arm64RetAddWords(uint32(fi.autosize))...)
 		}
 	}
 	// RET: BR LR (0xd65f03c0)
@@ -260,15 +312,16 @@ func arm64PrologueSpadjPC(fi arm64FrameInfo) int {
 	}
 	// Large frame: [SUB words][STP][ADD R20, SP]; SP moves at the ADD, whose
 	// position depends on how many words the SUB itself took (immediate,
-	// shifted immediate, or a materialised REGTMP sequence).
+	// shifted immediate, the two-word imm12 split, or a materialised REGTMP
+	// sequence).
 	return 4 * (len(arm64SubImmWords(uint32(fi.autosize), 20)) + 1)
 }
 
 // arm64ReturnEpilogueLen returns the byte length of the RET's epilogue up to
-// (but not including) the final RET instruction.  The ADD sequences share the
+// (but not including) the final RET instruction.  The lengths are read from
-// prologue's immediate ladder, so their length is read from the same helper
+// the same word-emitting helpers the epilogue uses rather than assumed: the
-// rather than assumed: a materialised autosize costs its MOV words plus the
+// leaf path shares the prologue's immediate ladder, and a materialised
-// ADD itself.
+// autosize costs its MOV words plus the ADD itself.
 func arm64ReturnEpilogueLen(fi arm64FrameInfo) int {
 	if fi.autosize == 0 {
 		return 0
@@ -280,8 +333,9 @@ func arm64ReturnEpilogueLen(fi arm64FrameInfo) int {
 	if fi.autosize <= 0xf0 {
 		return 8 // LDR + LDR.P
 	}
-	// LDP + the ADD ladder that deallocates the frame.
+	// LDP + the deallocation emitted by arm64RetAddWords, so the length
-	return 4 + 4*len(arm64AddImmWords(uint32(fi.autosize), 31))
+	// tracks whatever the MOVD ladder needs.
+	return 4 + 4*len(arm64RetAddWords(uint32(fi.autosize)))
 }
 
 // arm64ResolvePseudo translates a pseudo-register memory reference into a

asm/encodable.go

@@ -86,9 +86,16 @@ func Encodable(mnemonic string) bool {
 		"BSWAP",
 		"PREFETCHNTA", "PREFETCHT0", "PREFETCHT1", "PREFETCHT2",
 		"MOVBLZX", "MOVBQZX", "MOVWLZX", "MOVWQZX", "MOVWLSX", "MOVLQSX",
+		"MOVBWZX", "MOVBWSX", "MOVBLSX", "MOVBQSX", "MOVWQSX", "MOVLQZX",
 		"CVTSL2SD", "CVTSQ2SD",
 		"MOVOU", "MOVO", "MOVUPS", "MOVAPS", "MOVUPD", "MOVAPD", "MOVSD", "MOVSS":
 		return true
 	}
+	// Full-name dispatches the size split would eat (a trailing width
+	// letter that is part of the mnemonic).
+	switch upper {
+	case "PMOVMSKB":
+		return true
+	}
 	return false
 }

asm/encode.go

@@ -101,6 +101,11 @@ func (e *enc) encode(mnem string, ops []Operand) error {
 	if m, ok := sseBinTable[base]; ok {
 		return e.encodeSSEBin(m, ops)
 	}
+	// PMOVMSKB ends in a width letter the size split would eat, so it
+	// dispatches on the full name like the packed binaries above.
+	if upper == "PMOVMSKB" {
+		return e.encodePmovmskb(upper, ops)
+	}
 	switch base {
 	case "MOV":
 		return e.encodeMov(ops, size)
@@ -126,7 +131,8 @@ func (e *enc) encode(mnem string, ops []Operand) error {
 		return e.encodeBswap(ops, size)
 	case "PREFETCHNTA", "PREFETCHT0", "PREFETCHT1", "PREFETCHT2":
 		return e.encodePrefetch(base, ops)
-	case "MOVBLZX", "MOVBQZX", "MOVWLZX", "MOVWQZX", "MOVWLSX", "MOVLQSX":
+	case "MOVBLZX", "MOVBQZX", "MOVWLZX", "MOVWQZX", "MOVWLSX", "MOVLQSX",
+		"MOVBWZX", "MOVBWSX", "MOVBLSX", "MOVBQSX", "MOVWQSX", "MOVLQZX":
 		return e.encodeMovExtend(base, ops)
 	case "CVTSL2SD", "CVTSQ2SD":
 		return e.encodeCvtsi2sd(base == "CVTSQ2SD", ops)

asm/encode_test.go

@@ -357,6 +357,18 @@ func TestScalarGroundTruth(t *testing.T) {
 		{"MOVBQZX AL,R8", "MOVBQZX", []Operand{AL, r8}, "4c0fb6c0", "MOVZX"},
 		{"MOVWLZX AX,CX", "MOVWLZX", []Operand{AX, CX}, "0fb7c8", "MOVZX"},
 		{"MOVWQZX AX,R8", "MOVWQZX", []Operand{AX, r8}, "4c0fb7c0", "MOVZX"},
+		// The width pairs the toolchain accepts and GOROOT uses; bytes
+		// pinned from go tool asm (see testdata/verify/widen_amd64.s).
+		{"MOVBWZX (BX),R11W", "MOVBWZX", []Operand{Ptr(BX, 0, 1), Reg{idx: 11, size: 2}}, "66440fb61b", "MOVZX"},
+		{"MOVBWSX (BX),R11W", "MOVBWSX", []Operand{Ptr(BX, 0, 1), Reg{idx: 11, size: 2}}, "66440fbe1b", "MOVSX"},
+		{"MOVBLSX (BX),AX", "MOVBLSX", []Operand{Ptr(BX, 0, 1), AX}, "0fbe03", "MOVSX"},
+		{"MOVBQSX (BX),R8", "MOVBQSX", []Operand{Ptr(BX, 0, 1), r8}, "4c0fbe03", "MOVSX"},
+		{"MOVWQSX (BX),R9", "MOVWQSX", []Operand{Ptr(BX, 0, 2), r9}, "4c0fbf0b", "MOVSX"},
+		// A long to quad zero-extend is a plain 32-bit move.
+		{"MOVLQZX (BX),DX", "MOVLQZX", []Operand{Ptr(BX, 0, 4), DX}, "8b13", "MOV"},
+		{"MOVLQZX AX,DX", "MOVLQZX", []Operand{AX, DX}, "8bd0", "MOV"},
+		{"PMOVMSKB X1,AX", "PMOVMSKB", []Operand{vreg(t, "X1"), AX}, "660fd7c1", "PMOVMSKB"},
+		{"PMOVMSKB X11,CX", "PMOVMSKB", []Operand{vreg(t, "X11"), CX}, "66410fd7cb", "PMOVMSKB"},
 		{"CVTSL2SD R8,X13", "CVTSL2SD", []Operand{r8, vreg(t, "X13")}, "f2450f2ae8", "CVTSI2SD"},
 		{"CVTSL2SD AX,X0", "CVTSL2SD", []Operand{AX, vreg(t, "X0")}, "f20f2ac0", "CVTSI2SD"},
 		{"CVTSQ2SD R8,X13", "CVTSQ2SD", []Operand{r8, vreg(t, "X13")}, "f24d0f2ae8", "CVTSI2SD"},

asm/instrs.go

@@ -838,15 +838,24 @@ func (e *enc) encodeBswap(ops []Operand, size int) error {
 // width.  The source is narrower than the destination, so the plain size-suffix
 // convention does not apply to these names.
 var movExtendOp = map[string]struct {
-	op    []byte
+	op      []byte
-	dst64 bool
+	dstSize int
 }{
-	"MOVBLZX": {[]byte{0x0F, 0xB6}, false}, // byte → long, zero-extend
+	"MOVBLZX": {[]byte{0x0F, 0xB6}, 4}, // byte → long, zero-extend
-	"MOVBQZX": {[]byte{0x0F, 0xB6}, true},  // byte → quad, zero-extend
+	"MOVBQZX": {[]byte{0x0F, 0xB6}, 8}, // byte → quad, zero-extend
-	"MOVWLZX": {[]byte{0x0F, 0xB7}, false}, // word → long, zero-extend
+	"MOVWLZX": {[]byte{0x0F, 0xB7}, 4}, // word → long, zero-extend
-	"MOVWQZX": {[]byte{0x0F, 0xB7}, true},  // word → quad, zero-extend
+	"MOVWQZX": {[]byte{0x0F, 0xB7}, 8}, // word → quad, zero-extend
-	"MOVWLSX": {[]byte{0x0F, 0xBF}, false}, // word → long, sign-extend
+	"MOVWLSX": {[]byte{0x0F, 0xBF}, 4}, // word → long, sign-extend
-	"MOVLQSX": {[]byte{0x63}, true},        // long → quad, sign-extend (MOVSXD)
+	"MOVLQSX": {[]byte{0x63}, 8},       // long → quad, sign-extend (MOVSXD)
+	"MOVBWZX": {[]byte{0x0F, 0xB6}, 2}, // byte → word, zero-extend
+	"MOVBWSX": {[]byte{0x0F, 0xBE}, 2}, // byte → word, sign-extend
+	"MOVBLSX": {[]byte{0x0F, 0xBE}, 4}, // byte → long, sign-extend
+	"MOVBQSX": {[]byte{0x0F, 0xBE}, 8}, // byte → quad, sign-extend
+	"MOVWQSX": {[]byte{0x0F, 0xBF}, 8}, // word → quad, sign-extend
+	// A long → quad zero-extend is a plain 32-bit move: every 32-bit
+	// operation zero-extends its result into the full register, so the
+	// toolchain lowers MOVLQZX to the plain MOVL encoding.
+	"MOVLQZX": {[]byte{0x8B}, 4},
 }
 
 // encodeMovExtend encodes a mixed-width extending move: reg = dst (the wider
@@ -860,12 +869,30 @@ func (e *enc) encodeMovExtend(base string, ops []Operand) error {
 	if !ok {
 		return fmt.Errorf("%s destination must be a register", base)
 	}
-	size := 4
+	i := newInstr(spec.dstSize, spec.op)
-	if spec.dst64 {
+	if err := setRM(i, dstReg, ops[0], spec.dstSize); err != nil {
-		size = 8
+		return err
 	}
-	i := newInstr(size, spec.op)
+	return e.emit(i)
-	if err := setRM(i, dstReg, ops[0], size); err != nil {
+}
+
+// encodePmovmskb encodes PMOVMSKB, the legacy SSE2 byte mask extract: the
+// XMM source's sign bytes pack into a GP destination, 66 0F D7 /r.
+func (e *enc) encodePmovmskb(base string, ops []Operand) error {
+	if len(ops) != 2 {
+		return fmt.Errorf("%s expects 2 operands, got %d", base, len(ops))
+	}
+	srcReg, srcVec := vecReg(ops[0])
+	if !srcVec {
+		return fmt.Errorf("%s source must be an XMM register", base)
+	}
+	dstReg, ok := ops[1].(Reg)
+	if !ok {
+		return fmt.Errorf("%s destination must be a register", base)
+	}
+	i := newInstr(4, []byte{0x0F, 0xD7})
+	i.prefix = 0x66
+	if err := setRM(i, dstReg, srcReg, 4); err != nil {
 		return err
 	}
 	return e.emit(i)

asm/riscv_encode.go

@@ -65,7 +65,7 @@ func riscvRegNum(name string) int {
 		return 25
 	case "X26", "S10":
 		return 26
-	case "X27", "S11":
+	case "X27", "S11", "g":
 		return 27
 	case "X28", "T3":
 		return 28

cmd/gasm/main.go

@@ -938,11 +938,40 @@ func compareGroundTruth(img *asm.Image, gt map[string][]byte) (matched, total, d
 				goCmp[j] = 0
 			}
 		}
-		if bytes.Equal(gasmCmp, goCmp) {
+		// The toolchain pads text symbols to 16-byte boundaries with
+		// zeros, so a function whose size is not a multiple of 16
+		// carries trailing zeros in the ground truth that are not part
+		// of the encoding.  Compare up to the shorter side and require
+		// the remainder of whichever is longer to be zero, so padding
+		// never masks a real difference.
+		cmpLen := min(len(gasmCmp), len(goCmp))
+		equal := bytes.Equal(gasmCmp[:cmpLen], goCmp[:cmpLen])
+		if equal {
+			for _, b := range gasmCmp[cmpLen:] {
+				if b != 0 {
+					equal = false
+					break
+				}
+			}
+		}
+		if equal {
+			for _, b := range goCmp[cmpLen:] {
+				if b != 0 {
+					equal = false
+					break
+				}
+			}
+		}
+		if equal {
 			matched++
-			if len(fn.Relocs) > 0 {
+			switch {
+			case len(fn.Relocs) > 0 && len(goCmp) > cmpLen:
+				fmt.Printf("  %s: MATCH (%d bytes, %d relocs masked, %d padding)\n", fn.Name, fn.Size, len(fn.Relocs), len(goCmp)-cmpLen)
+			case len(fn.Relocs) > 0:
 				fmt.Printf("  %s: MATCH (%d bytes, %d relocs masked)\n", fn.Name, fn.Size, len(fn.Relocs))
-			} else {
+			case len(goCmp) > cmpLen:
+				fmt.Printf("  %s: MATCH (%d bytes, %d padding)\n", fn.Name, fn.Size, len(goCmp)-cmpLen)
+			default:
 				fmt.Printf("  %s: MATCH (%d bytes)\n", fn.Name, fn.Size)
 			}
 		} else {
@@ -990,8 +1019,8 @@ that tolerate nil pointers and zero lengths in their arguments.
 With -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
+checks run when the host matches the file's architecture, on all four
-loong64, which is ground-truth only for now).
+architectures.
 
 With -fuzz, each function with a // func signature is differentially fuzzed
 against the go-tool-asm version in a subprocess (so a crash on a partial
@@ -1033,16 +1062,13 @@ each entry reproduces.
 	path := set.Arg(0)
 	targetArch := arch.FromFilename(path)
 	// JIT execution runs when the host CPU matches the kernel's
-	// architecture, except loong64: its trampoline is implemented but not
+	// architecture; every trampoline is validated end to end under
-	// yet validated against real hardware (the Go runtime cannot start
+	// qemu-user emulation (the loong64 one included, via the raw-address
-	// under the available loong64 emulators), so those kernels take the
+	// leave handoff).
-	// toolchain-comparison path.
+	if targetArch != hostArch() {
-	if targetArch != hostArch() || targetArch == arch.LOONG64 {
 		// No JIT on this host: ground truth and profile remain available for
 		// every architecture, because cmdVerifyNonJIT assembles and compares
-		// against the toolchain without executing anything.  (loong64 is
+		// against the toolchain without executing anything.
-		// ground-truth-only everywhere for now: its trampoline is implemented
-		// but not yet validated against real hardware.)
 		switch targetArch {
 		case arch.AMD64, arch.RISCV, arch.LOONG64, arch.ARM64:
 			return cmdVerifyNonJIT(path, targetArch, *groundTruth, *profile)

cmd/gasm/main_test.go

@@ -15,6 +15,7 @@ import (
 	"testing"
 
 	"sourcedock.dev/petrbalvin/gasm-devkit/arch"
+	"sourcedock.dev/petrbalvin/gasm-devkit/asm"
 )
 
 const clean = "#include \"textflag.h\"\n" +
@@ -440,3 +441,22 @@ func TestRunCorpusAudit(t *testing.T) {
 		t.Errorf("arm64 unencodable reasons = %d, want 1", r)
 	}
 }
+
+// TestCompareGroundTruthPadding pins the padding-aware ground-truth
+// comparison: the toolchain pads text symbols to 16-byte boundaries, so
+// trailing zeros in the reference must not read as a mismatch, while any
+// non-zero tail still must.
+func TestCompareGroundTruthPadding(t *testing.T) {
+	code := []byte{0x48, 0x8b, 0x07, 0xc3} // 4 bytes, not a multiple of 16
+	img := &asm.Image{Code: code, Funcs: []asm.FuncLayout{{Name: "f", Offset: 0, Size: len(code)}}}
+	padded := append(append([]byte(nil), code...), 0, 0, 0)
+	matched, total, diffs := compareGroundTruth(img, map[string][]byte{"f": padded})
+	if matched != 1 || total != 1 || diffs != 0 {
+		t.Fatalf("zero padding should match: matched=%d total=%d diffs=%d", matched, total, diffs)
+	}
+	dirty := append(append([]byte(nil), code...), 0, 0x90, 0)
+	matched, _, diffs = compareGroundTruth(img, map[string][]byte{"f": dirty})
+	if matched != 0 || diffs != 1 {
+		t.Fatalf("non-zero padding must mismatch: matched=%d diffs=%d", matched, diffs)
+	}
+}

docs/ARCHITECTURE.md

@@ -410,9 +410,9 @@ every architecture too: `enterJITChecked` plants sentinels in the registers
 the Go ABI fixes across calls (amd64 `BP`/`R14`, arm64 `R29`/`R28`, riscv64
 `X27`, loong64 `R22`; the latter two keep no hardware frame pointer) and the
 raw return trampoline `leaveJITCheckedRaw` verifies them, restoring the
-saved registers before Go code resumes.  riscv64 is validated end to
+saved registers before Go code resumes.  All three non-amd64 trampolines
-end under qemu-user emulation; arm64 shares the same stack convention and
+are validated end to end under qemu-user emulation, the loong64 one
-fix; loong64 stays ground-truth-only until hardware validation.
+through its raw-address leave handoff.
 `gasm verify` runs the JIT checks when the host
 matches the kernel's architecture and the toolchain comparisons
 elsewhere.

docs/CLI.md

@@ -219,8 +219,7 @@ 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
+invokes such a function with valid data.
-until hardware validation.
 
 ```sh
 gasm verify --ground-truth hello_amd64.s

docs/man/gasm-verify.1

@@ -20,8 +20,7 @@ With
 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
+when the host matches the file's architecture, on all four architectures.
-is ground-truth only for now).
 .PP
 With
 .BR \-fuzz ,

testdata/verify/abi_arm64.s

@@ -22,9 +22,9 @@ TEXT ·dirtyFP(SB), NOSPLIT, $0-16
 	RET
 
 // func dirtyG(a int64) int64
-// Deliberately clobbers R28, the goroutine pointer (a serious ABI violation).
+// Deliberately clobbers g, the goroutine pointer (R28; a serious ABI violation).
 TEXT ·dirtyG(SB), NOSPLIT, $0-16
-	MOVD $0x5678, R28
+	MOVD $0x5678, g
 	MOVD a+0(FP), R0
 	MOVD R0, ret+8(FP)
 	RET

testdata/verify/abi_loong64.s

@@ -13,9 +13,9 @@ TEXT ·cleanAdd(SB), NOSPLIT, $0-24
 	RET
 
 // func dirtyG(a int64) int64
-// Deliberately clobbers R22, the goroutine pointer (a serious ABI violation).
+// Deliberately clobbers g, the goroutine pointer (R22; a serious ABI violation).
 TEXT ·dirtyG(SB), NOSPLIT, $0-16
-	MOVV $0x5678, R22
+	MOVV $0x5678, g
 	MOVV a+0(FP), R4
 	MOVV R4, ret+8(FP)
 	RET

testdata/verify/abi_riscv64.s

@@ -13,9 +13,9 @@ TEXT ·cleanAdd(SB), NOSPLIT, $0-24
 	RET
 
 // func dirtyG(a int64) int64
-// Deliberately clobbers X27, the goroutine pointer (a serious ABI violation).
+// Deliberately clobbers g, the goroutine pointer (X27; a serious ABI violation).
 TEXT ·dirtyG(SB), NOSPLIT, $0-16
-	MOV $0x5678, X27
+	MOV $0x5678, g
 	MOV a+0(FP), X5
 	MOV X5, ret+8(FP)
 	RET

testdata/verify/basic_loong64.s

@@ -37,7 +37,10 @@ TEXT ·imm(SB), NOSPLIT, $0-0
 	MOVV $0x12345, R17
 	RET
 
-// branch exercises conditional and unconditional control flow.
+// branch exercises conditional and unconditional control flow.  Every
+// path must terminate: the smoke harness calls functions with a zeroed
+// argument block, and a $0-0 function's registers carry whatever the
+// caller left, so a branch maze can reach any label.
 TEXT ·branch(SB), NOSPLIT, $0-0
 	BEQ  R4, R5, done
 	BNE  R6, R7, skip
@@ -50,7 +53,10 @@ skip:
 	JMP  loop
 
 loop:
-	JAL  skip
+	JAL  fin
+	RET
+
+fin:
 	RET
 
 done:

testdata/verify/bigframe2_arm64.s

@@ -0,0 +1,69 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Large frames across every immediate band of the prologue SUB and the RET
+// epilogue, byte-parity-checked against go tool asm:
+//
+//   $5000     autosize 5024    one 16-bit chunk, materialised into REGTMP
+//   $65664    autosize 65680   split into two imm12 instructions
+//   $70000    autosize 70016   split into two imm12 instructions
+//   $65520    autosize 65536   one shifted imm12 in the prologue, a logical
+//                              immediate (ORR) in the non-leaf epilogue
+//   $16777232 autosize 16777248 wider than 24 bits, MOVZ/MOVK into REGTMP
+
+#include "textflag.h"
+
+TEXT ·leaf5000(SB), NOSPLIT, $5000-0
+	MOVD R0, R1
+	MOVD R1, R2
+	RET
+
+TEXT ·leaf65664(SB), NOSPLIT, $65664-0
+	MOVD R0, R1
+	MOVD R1, R2
+	RET
+
+TEXT ·leaf70000(SB), NOSPLIT, $70000-0
+	MOVD R0, R1
+	MOVD R1, R2
+	RET
+
+TEXT ·leaf65520(SB), NOSPLIT, $65520-0
+	MOVD R0, R1
+	MOVD R1, R2
+	MOVD R2, R3
+	MOVD R3, R4
+	RET
+
+TEXT ·nl5000(SB), NOSPLIT, $5000-0
+	MOVD R0, R1
+	MOVD R1, R2
+	CALL ·other(SB)
+	RET
+
+TEXT ·nl65664(SB), NOSPLIT, $65664-0
+	MOVD R0, R1
+	CALL ·other(SB)
+	RET
+
+TEXT ·nl70000(SB), NOSPLIT, $70000-0
+	MOVD R0, R1
+	CALL ·other(SB)
+	RET
+
+TEXT ·nl65520(SB), NOSPLIT, $65520-0
+	MOVD R0, R1
+	MOVD R1, R2
+	MOVD R2, R3
+	CALL ·other(SB)
+	RET
+
+TEXT ·nlhuge(SB), NOSPLIT, $16777232-0
+	CALL ·other(SB)
+	RET
+
+TEXT ·other(SB), NOSPLIT, $0-0
+	MOVD R0, R1
+	MOVD R1, R2
+	MOVD R2, R3
+	RET

testdata/verify/exclusive_arm64.s

@@ -0,0 +1,81 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Exclusive load/store family, LSE atomics and their memory operands,
+// byte-parity-checked against go tool asm.  The toolchain parses the FIRST
+// register of an exclusive store as the data register and the LAST as the
+// status register, and takes register pairs as (Rt1, Rt2) operands.
+
+#include "textflag.h"
+
+TEXT ·loads(SB), NOSPLIT, $0-0
+	LDXR   (R1), R2
+	LDXRB  (R1), R3
+	LDXRH  (R1), R4
+	LDXRW  (R1), R5
+	LDAXR  (R1), R2
+	LDAXRB (R1), R3
+	LDAXRH (R1), R4
+	LDAXRW (R1), R5
+	LDXR   (RSP), R2
+	LDXRB  (RSP), R3
+	LDXRH  (RSP), R4
+	LDXRW  (RSP), R5
+	LDAXR  (RSP), R2
+	LDAXRB (RSP), R3
+	LDAXRH (RSP), R4
+	RET
+
+TEXT ·stores(SB), NOSPLIT, $0-0
+	STXR   R2, (R1), R6
+	STXRB  R3, (R1), R6
+	STXRH  R4, (R1), R6
+	STXRW  R5, (R1), R6
+	STLXR  R2, (R1), R6
+	STLXRB R3, (R1), R6
+	STLXRH R4, (R1), R6
+	STLXRW R5, (R1), R6
+	STXR   R2, (RSP), R6
+	STXRB  R3, (RSP), R6
+	STXRH  R4, (RSP), R6
+	STXRW  R5, (RSP), R6
+	STLXR  R2, (RSP), R6
+	STLXRB R3, (RSP), R6
+	STLXRH R4, (RSP), R6
+	RET
+
+TEXT ·pairs(SB), NOSPLIT, $0-0
+	LDXP   (R1), (R2, R3)
+	LDXPW  (R1), (R2, R3)
+	LDAXP  (R1), (R2, R3)
+	LDAXPW (R1), (R2, R3)
+	STXP   (R2, R3), (R1), R6
+	STXPW  (R2, R3), (R1), R6
+	STLXP  (R2, R3), (R1), R6
+	STLXPW (R2, R3), (R1), R6
+	LDXP   (RSP), (R2, R3)
+	LDXPW  (RSP), (R2, R3)
+	LDAXP  (RSP), (R4, R5)
+	LDAXPW (RSP), (R4, R5)
+	STXP   (R2, R3), (RSP), R6
+	STXPW  (R2, R3), (RSP), R6
+	STLXP  (R4, R5), (RSP), R7
+	RET
+
+TEXT ·atomics(SB), NOSPLIT, $0-0
+	LDADDB R2, (R1), R3
+	LDADDH R2, (R1), R3
+	LDADDW R2, (R1), R3
+	LDADDD R2, (R1), R3
+	LDADDB R2, (R1), ZR
+	LDADDH R2, (R1), ZR
+	LDADDW R2, (R1), ZR
+	LDADDD R2, (R1), ZR
+	CASW   R2, (R1), R3
+	CASD   R2, (R1), R3
+	CASW   R2, (R1), ZR
+	CASD   R2, (R1), ZR
+	SWPW   R2, (R1), R3
+	SWPD   R2, (R1), R3
+	SWPD   R2, (R1), ZR
+	RET

testdata/verify/widen_amd64.s

@@ -0,0 +1,39 @@
+// Mixed-width sign- and zero-extending moves plus PMOVMSKB, the spellings
+// GOROOT's runtime and bytealg kernels use.  Every result is folded back so
+// no instruction is dead.
+
+#include "textflag.h"
+
+// func widen(p *byte) uint64
+TEXT ·widen(SB), NOSPLIT, $0-16
+	MOVBQZX 0(DI), AX
+	MOVWQZX 2(DI), CX
+	ADDQ    CX, AX
+	MOVLQZX 4(DI), DX
+	ADDQ    DX, AX
+	MOVBQSX 8(DI), R8
+	ADDQ    R8, AX
+	MOVWQSX 12(DI), R9
+	ADDQ    R9, AX
+	MOVBLSX 16(DI), R10
+	ADDL    R10, AX
+	MOVLQSX 20(DI), R11
+	ADDQ    R11, AX
+	MOVQ    AX, ret+8(FP)
+	RET
+
+// func widenw(p *byte) int32
+TEXT ·widenw(SB), NOSPLIT, $0-16
+	MOVBWZX 0(DI), AX
+	MOVBWSX 1(DI), CX
+	ADDL    CX, AX
+	MOVLQZX AX, DX
+	MOVL    DX, ret+8(FP)
+	RET
+
+// func mask(x *XMM) int
+TEXT ·mask(SB), NOSPLIT, $0-16
+	MOVOU    0(DI), X1
+	PMOVMSKB X1, AX
+	MOVQ     AX, ret+8(FP)
+	RET

verify/abi_arch_test.go

@@ -42,8 +42,12 @@ func TestABIArm64(t *testing.T) {
 		t.Errorf("cleanAdd: %s", report)
 	}
 
-	// dirtyFP clobbers the frame pointer (R29).
+	// dirtyFP clobbers the frame pointer (R29).  The kernel passes its
-	out, report, err = k.CallFuncChecked("dirtyFP", make([]byte, 16))
+	// argument through, so the argument must carry the expected value the
+	// way the amd64 twin test seeds it.
+	args = make([]byte, 16)
+	PutUint64(args, 0, 0x1234)
+	out, report, err = k.CallFuncChecked("dirtyFP", args)
 	if err != nil {
 		t.Fatalf("CallFuncChecked: %v", err)
 	}
@@ -57,11 +61,17 @@ func TestABIArm64(t *testing.T) {
 		t.Errorf("dirtyFP: only R29 should be clobbered: %s", report)
 	}
 
-	// dirtyG clobbers the goroutine pointer (R28).
+	// dirtyG clobbers the goroutine pointer (R28) and still returns its
-	_, report, err = k.CallFuncChecked("dirtyG", make([]byte, 16))
+	// argument.
+	args = make([]byte, 16)
+	PutUint64(args, 0, 0x5678)
+	out, report, err = k.CallFuncChecked("dirtyG", args)
 	if err != nil {
 		t.Fatalf("CallFuncChecked: %v", err)
 	}
+	if got := int64(GetUint64(out, 8)); got != 0x5678 {
+		t.Errorf("dirtyG returned %d, want %d", got, int64(0x5678))
+	}
 	if !report.GClobbered {
 		t.Error("dirtyG: expected g clobbered, but report says clean")
 	}