gasm-sdk/asm/link_test.go

// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: BSD-3-Clause

package asm

import (
	"strings"
	"testing"

	"sourcedock.dev/petrbalvin/gasm-devkit/parser"
)

// TestAssembleFileStaticData checks the whole-image layout — code, padding
// 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", `
#include "textflag.h"
TEXT ·load(SB), NOSPLIT, $0
	VMOVDQU mask<>(SB), X15
	MOVL small<>(SB), AX
	RET
GLOBL mask<>(SB), RODATA, $16
DATA mask<>+0(SB)/4, $0x80020100
DATA mask<>+4(SB)/4, $0x80050403
DATA mask<>+8(SB)/4, $0x80080706
DATA mask<>+12(SB)/4, $0x800B0A09
GLOBL small<>(SB), RODATA, $4
DATA small<>+0(SB)/4, $0x1234
`)
	if len(errs) > 0 {
		t.Fatalf("parse: %v", errs)
	}
	img, err := AssembleFile(f)
	if err != nil {
		t.Fatalf("AssembleFile: %v", err)
	}

	// Code (15 bytes) + 1 pad byte to align the data section to 16:
	//   VMOVDQU mask<>(SB), X15   c5 7a 6f 3d 08 00 00 00   (disp = 16 − 8)
	//   MOVL small<>(SB), AX      8b 05 12 00 00 00         (disp = 32 − 14)
	//   RET                       c3
	// Data: pad, mask (16 bytes), small (4 bytes).
	want := "c57a6f3d080000008b0512000000c300" +
		"000102800304058006070880090a0b80" +
		"34120000"
	if got := strings.ReplaceAll(hexBytes(img.Bytes()), " ", ""); got != want {
		t.Errorf("image bytes:\n got  %s\n want %s", got, want)
	}
	if img.Symbols["mask"] != 16 || img.Symbols["small"] != 32 {
		t.Errorf("symbol offsets = %v, want mask=16 small=32", img.Symbols)
	}
	if len(img.Funcs) != 1 || img.Funcs[0].Name != "load" || img.Funcs[0].Size != 15 {
		t.Errorf("funcs = %+v", img.Funcs)
	}
}

// TestAssembleFileErrors checks the static-symbol error paths.
func TestAssembleFileErrors(t *testing.T) {
	cases := []struct {
		name string
		src  string
		want string // substring of the error
	}{
		{
			"undefined symbol",
			`
#include "textflag.h"
TEXT ·f(SB), NOSPLIT, $0
	VMOVDQU nope<>(SB), X0
	RET
`,
			"undefined symbol",
		},
		{
			"DATA without GLOBL",
			`
#include "textflag.h"
TEXT ·f(SB), NOSPLIT, $0
	RET
DATA orphan<>+0(SB)/4, $1
`,
			"no matching GLOBL",
		},
		{
			"DATA exceeds size",
			`
#include "textflag.h"
TEXT ·f(SB), NOSPLIT, $0
	RET
GLOBL tiny<>(SB), RODATA, $4
DATA tiny<>+0(SB)/8, $1
`,
			"exceeds GLOBL size",
		},
		{
			"DATA bad width",
			`
#include "textflag.h"
TEXT ·f(SB), NOSPLIT, $0
	RET
GLOBL odd<>(SB), RODATA, $4
DATA odd<>+0(SB)/3, $1
`,
			"invalid width",
		},
	}
	for _, c := range cases {
		f, errs := parser.Parse("e_amd64.s", c.src)
		if len(errs) > 0 {
			t.Fatalf("%s: parse: %v", c.name, errs)
		}
		if _, err := AssembleFile(f); err == nil || !strings.Contains(err.Error(), c.want) {
			t.Errorf("%s: error %v, want substring %q", c.name, err, c.want)
		}
	}

	// A static-symbol operand is unresolvable in single-function assembly.
	fn := firstText(t, `
#include "textflag.h"
TEXT ·f(SB), NOSPLIT, $0
	MOVQ x<>(SB), AX
	RET
GLOBL x<>(SB), RODATA, $8
DATA x<>+0(SB)/4, $1
`)
	if _, _, err := Assemble(fn); err == nil || !strings.Contains(err.Error(), "file-level assembly") {
		t.Errorf("single-function SB: error %v, want a file-level-assembly error", err)
	}
}