petrbalvin
a829b8f321
The toolchain's disassembler prints the segment-prefixed disp32 absolute as FS:0, but the bare-name branch read the segment register alone and dropped the offset, so MOVQ FS:0, DX silently encoded a register move. The colon-offset form now lowers to the same segment-absolute operand the 0(FS) spelling takes. Assisted-by: GLM 5.3 Flash
49 lines
1.5 KiB
Go
49 lines
1.5 KiB
Go
// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
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// SPDX-License-Identifier: BSD-3-Clause
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package asm
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import (
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"encoding/hex"
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"strings"
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"testing"
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"sourcedock.dev/petrbalvin/gasm-sdk/parser"
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)
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// TestRenderedTextEncodes pins the encoder against the disassembler's
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// renderings: every line here is a text the toolchain's own decoder prints
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// for bytes its assembler produced (the disasm package's parity fixtures),
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// so assembling the printed text must reproduce those bytes. Each row was
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// read back through the toolchain's decoder; the hex is the fixture's.
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func TestRenderedTextEncodes(t *testing.T) {
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for _, tt := range []struct {
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text string
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want string
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}{
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// The segment-absolute rendering lowers to the FS-prefixed disp32
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// absolute, exactly what the 0(FS) spelling encodes.
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{"MOVQ FS:0, DX", "64488b142500000000"},
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} {
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src := "TEXT \u00b7k(SB), NOSPLIT, $0\n\t" + tt.text + "\n\tRET\n"
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f, errs := parser.Parse("k.s", src)
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if len(errs) > 0 {
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t.Errorf("%s: parse: %v", tt.text, errs[0])
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continue
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}
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img, err := AssembleFile(f)
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if err != nil {
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t.Errorf("%s: assemble: %v", tt.text, err)
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continue
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}
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fn := img.Funcs[0]
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code := img.Code[fn.Offset : fn.Offset+fn.Size]
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// The no-fallthrough rule appends the RET; the pinned instruction is
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// the prefix.
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got := hex.EncodeToString(code)
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if !strings.HasPrefix(got, tt.want) {
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t.Errorf("%s: bytes %s, want prefix %s", tt.text, got, tt.want)
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}
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}
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}
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