<!--{
	"Title": "A Quick Guide to Go's Assembler",
	"Path":  "/doc/asm"
}-->

<h2 id="introduction">A Quick Guide to Go's Assembler</h2>

<p>
This document is a quick outline of the unusual form of assembly language used by the <code>gc</code> Go compiler.
The document is not comprehensive.
</p>

<p>
The assembler is based on the input style of the Plan 9 assemblers, which is documented in detail

// license that can be found in the LICENSE file.

// This file encapsulates some of the odd characteristics of the
// s390x instruction set, to minimize its interaction
// with the core of the assembler.

package arch

import (
	"cmd/internal/obj/s390x"
)

func jumpS390x(word string) bool {
	switch word {
	case "BRC",
		"BC",
		"BCL",
		"BEQ",
		"BGE",
		"BGT",
		"BL",
		"BLE",

// license that can be found in the LICENSE file.

// This file encapsulates some of the odd characteristics of the
// 64-bit PowerPC (PPC64) instruction set, to minimize its interaction
// with the core of the assembler.

package arch

import (
	"cmd/internal/obj"
	"cmd/internal/obj/ppc64"
)

func jumpPPC64(word string) bool {
	switch word {

// license that can be found in the LICENSE file.

// This file encapsulates some of the odd characteristics of the
// Loong64 (LoongArch64) instruction set, to minimize its interaction
// with the core of the assembler.

package arch

import (
	"cmd/internal/obj"
	"cmd/internal/obj/loong64"
	"errors"
	"fmt"
)

func jumpLoong64(word string) bool {
	switch word {

	"fmt"
	"internal/buildcfg"
	"os"
	"path/filepath"
	"regexp"
	"sort"
	"strconv"
	"strings"
	"testing"

	"cmd/asm/internal/lex"
	"cmd/internal/obj"
)

// An end-to-end test for the assembler: Do we print what we parse?
// Output is generated by, in effect, turning on -S and comparing the
// result against a golden file.

func testEndToEnd(t *testing.T, goarch, file string) {

// license that can be found in the LICENSE file.

// This file encapsulates some of the odd characteristics of the ARM64
// instruction set, to minimize its interaction with the core of the
// assembler.

package arch

import (
	"cmd/internal/obj"
	"cmd/internal/obj/arm64"
	"errors"
)

var arm64LS = map[string]uint8{
	"P": arm64.C_XPOST,
	"W": arm64.C_XPRE,
}

// license that can be found in the LICENSE file.

// This file encapsulates some of the odd characteristics of the ARM
// instruction set, to minimize its interaction with the core of the
// assembler.

package arch

import (
	"strings"

	"cmd/internal/obj"
	"cmd/internal/obj/arm"
)

var armLS = map[string]uint8{
	"U":  arm.C_UBIT,
	"S":  arm.C_SBIT,
	"W":  arm.C_WBIT,

Cherry Zhang <******@****.***> 1554826227 -0400

	// For backwards compatibility, MOVW $const,Rx and MOVWZ $const,Rx assemble identically
	// and accept the same constants.
	MOVW $2147483648, R5            // 64058000
	MOVWZ $-2147483648, R5          // 3ca08000

	// TODO: These are preprocessed by the assembler into MOVD $const>>shift, R5; SLD $shift, R5.

// license that can be found in the LICENSE file.

// The cases are auto-generated by disassembler.
// The uncommented cases means they can be handled by assembler
// and they are consistent with disassembler decoding.
// TODO means they cannot be handled by current assembler.

#include "../../../../../runtime/textflag.h"

TEXT asmtest(SB),DUPOK|NOSPLIT,$-8