// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package x86asm
import (
"fmt"
"strings"
)
type SymLookup func(uint64) (string, uint64)
// GoSyntax returns the Go assembler syntax for the instruction.
// The syntax was originally defined by Plan 9.
// The pc is the program counter of the instruction, used for expanding
// PC-relative addresses into absolute ones.
// The symname function queries the symbol table for the program
// being disassembled. Given a target address it returns the name and base
// address of the symbol containing the target, if any; otherwise it returns "", 0.
func GoSyntax(inst Inst, pc uint64, symname SymLookup) string {
if symname == nil {
symname = func(uint64) (string, uint64) { return "", 0 }
}
var args []string
for i := len(inst.Args) - 1; i >= 0; i-- {
a := inst.Args[i]
if a == nil {
continue
}
args = append(args, plan9Arg(&inst, pc, symname, a))
}
var rep string
var last Prefix
for _, p := range inst.Prefix {
if p == 0 || p.IsREX() || p.IsVEX() {
break
}
switch {
// Don't show prefixes implied by the instruction text.
case p&0xFF00 == PrefixImplicit:
continue
// Only REP and REPN are recognized repeaters. Plan 9 syntax
// treats them as separate opcodes.
case p&0xFF == PrefixREP:
rep = "REP; "
case p&0xFF == PrefixREPN:
rep = "REPNE; "
default:
last = p
}
}
prefix := ""
switch last & 0xFF {
case 0, 0x66, 0x67:
// ignore
default:
prefix += last.String() + " "
}
op := inst.Op.String()
if plan9Suffix[inst.Op] {
s := inst.DataSize
if inst.MemBytes != 0 {
s = inst.MemBytes * 8
}
switch s {
case 8:
op += "B"
case 16:
op += "W"
case 32:
op += "L"
case 64:
op += "Q"
}
}
if args != nil {
op += " " + strings.Join(args, ", ")
}
return rep + prefix + op
}
func plan9Arg(inst *Inst, pc uint64, symname func(uint64) (string, uint64), arg Arg) string {
switch a := arg.(type) {
case Reg:
return plan9Reg[a]
case Rel:
if pc == 0 {
break
}
// If the absolute address is the start of a symbol, use the name.
// Otherwise use the raw address, so that things like relative
// jumps show up as JMP 0x123 instead of JMP f+10(SB).
// It is usually easier to search for 0x123 than to do the mental
// arithmetic to find f+10.
addr := pc + uint64(inst.Len) + uint64(a)
if s, base := symname(addr); s != "" && addr == base {
return fmt.Sprintf("%s(SB)", s)
}
return fmt.Sprintf("%#x", addr)
case Imm:
if s, base := symname(uint64(a)); s != "" {
suffix := ""
if uint64(a) != base {
suffix = fmt.Sprintf("%+d", uint64(a)-base)
}
return fmt.Sprintf("$%s%s(SB)", s, suffix)
}
if inst.Mode == 32 {
return fmt.Sprintf("$%#x", uint32(a))
}
if Imm(int32(a)) == a {
return fmt.Sprintf("$%#x", int64(a))
}
return fmt.Sprintf("$%#x", uint64(a))
case Mem:
if s, disp := memArgToSymbol(a, pc, inst.Len, symname); s != "" {
suffix := ""
if disp != 0 {
suffix = fmt.Sprintf("%+d", disp)
}
return fmt.Sprintf("%s%s(SB)", s, suffix)
}
s := ""
if a.Segment != 0 {
s += fmt.Sprintf("%s:", plan9Reg[a.Segment])
}
if a.Disp != 0 {
s += fmt.Sprintf("%#x", a.Disp)
} else {
s += "0"
}
if a.Base != 0 {
s += fmt.Sprintf("(%s)", plan9Reg[a.Base])
}
if a.Index != 0 && a.Scale != 0 {
s += fmt.Sprintf("(%s*%d)", plan9Reg[a.Index], a.Scale)
}
return s
}
return arg.String()
}
func memArgToSymbol(a Mem, pc uint64, instrLen int, symname SymLookup) (string, int64) {
if a.Segment != 0 || a.Disp == 0 || a.Index != 0 || a.Scale != 0 {
return "", 0
}
var disp uint64
switch a.Base {
case IP, EIP, RIP:
disp = uint64(a.Disp + int64(pc) + int64(instrLen))
case 0:
disp = uint64(a.Disp)
default:
return "", 0
}
s, base := symname(disp)
return s, int64(disp) - int64(base)
}
var plan9Suffix = [maxOp + 1]bool{
ADC: true,
ADD: true,
AND: true,
BSF: true,
BSR: true,
BT: true,
BTC: true,
BTR: true,
BTS: true,
CMP: true,
CMPXCHG: true,
CVTSI2SD: true,
CVTSI2SS: true,
CVTSD2SI: true,
CVTSS2SI: true,
CVTTSD2SI: true,
CVTTSS2SI: true,
DEC: true,
DIV: true,
FLDENV: true,
FRSTOR: true,
IDIV: true,
IMUL: true,
IN: true,
INC: true,
LEA: true,
MOV: true,
MOVNTI: true,
MUL: true,
NEG: true,
NOP: true,
NOT: true,
OR: true,
OUT: true,
POP: true,
POPA: true,
PUSH: true,
PUSHA: true,
RCL: true,
RCR: true,
ROL: true,
ROR: true,
SAR: true,
SBB: true,
SHL: true,
SHLD: true,
SHR: true,
SHRD: true,
SUB: true,
TEST: true,
XADD: true,
XCHG: true,
XOR: true,
}
var plan9Reg = [...]string{
AL: "AL",
CL: "CL",
BL: "BL",
DL: "DL",
AH: "AH",
CH: "CH",
BH: "BH",
DH: "DH",
SPB: "SP",
BPB: "BP",
SIB: "SI",
DIB: "DI",
R8B: "R8",
R9B: "R9",
R10B: "R10",
R11B: "R11",
R12B: "R12",
R13B: "R13",
R14B: "R14",
R15B: "R15",
AX: "AX",
CX: "CX",
BX: "BX",
DX: "DX",
SP: "SP",
BP: "BP",
SI: "SI",
DI: "DI",
R8W: "R8",
R9W: "R9",
R10W: "R10",
R11W: "R11",
R12W: "R12",
R13W: "R13",
R14W: "R14",
R15W: "R15",
EAX: "AX",
ECX: "CX",
EDX: "DX",
EBX: "BX",
ESP: "SP",
EBP: "BP",
ESI: "SI",
EDI: "DI",
R8L: "R8",
R9L: "R9",
R10L: "R10",
R11L: "R11",
R12L: "R12",
R13L: "R13",
R14L: "R14",
R15L: "R15",
RAX: "AX",
RCX: "CX",
RDX: "DX",
RBX: "BX",
RSP: "SP",
RBP: "BP",
RSI: "SI",
RDI: "DI",
R8: "R8",
R9: "R9",
R10: "R10",
R11: "R11",
R12: "R12",
R13: "R13",
R14: "R14",
R15: "R15",
IP: "IP",
EIP: "IP",
RIP: "IP",
F0: "F0",
F1: "F1",
F2: "F2",
F3: "F3",
F4: "F4",
F5: "F5",
F6: "F6",
F7: "F7",
M0: "M0",
M1: "M1",
M2: "M2",
M3: "M3",
M4: "M4",
M5: "M5",
M6: "M6",
M7: "M7",
X0: "X0",
X1: "X1",
X2: "X2",
X3: "X3",
X4: "X4",
X5: "X5",
X6: "X6",
X7: "X7",
X8: "X8",
X9: "X9",
X10: "X10",
X11: "X11",
X12: "X12",
X13: "X13",
X14: "X14",
X15: "X15",
CS: "CS",
SS: "SS",
DS: "DS",
ES: "ES",
FS: "FS",
GS: "GS",
GDTR: "GDTR",
IDTR: "IDTR",
LDTR: "LDTR",
MSW: "MSW",
TASK: "TASK",
CR0: "CR0",
CR1: "CR1",
CR2: "CR2",
CR3: "CR3",
CR4: "CR4",
CR5: "CR5",
CR6: "CR6",
CR7: "CR7",
CR8: "CR8",
CR9: "CR9",
CR10: "CR10",
CR11: "CR11",
CR12: "CR12",
CR13: "CR13",
CR14: "CR14",
CR15: "CR15",
DR0: "DR0",
DR1: "DR1",
DR2: "DR2",
DR3: "DR3",
DR4: "DR4",
DR5: "DR5",
DR6: "DR6",
DR7: "DR7",
DR8: "DR8",
DR9: "DR9",
DR10: "DR10",
DR11: "DR11",
DR12: "DR12",
DR13: "DR13",
DR14: "DR14",
DR15: "DR15",
TR0: "TR0",
TR1: "TR1",
TR2: "TR2",
TR3: "TR3",
TR4: "TR4",
TR5: "TR5",
TR6: "TR6",
TR7: "TR7",
}
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