func (i insnO) op(code gen.OpCoder, reg regs.R) {
if reg >= 8 {
panic("register not supported by instruction")
}
code.WriteByte(i.opbase + byte(reg))
}
func writeSibTo(code gen.OpCoder, scale byte, index, base regs.R) {
if scale >= 4 {
panic("scale factor out of bounds")
}
code.WriteByte((scale << 6) | (byte(index&7) << 3) | byte(base&7))
}
func (i insnPrefixMI) opImm(code gen.OpCoder, t types.T, reg regs.R, value int32) {
opcode, imm := i.immOpcode(value)
i.prefix.writeTo(code, t, 0, 0, byte(reg))
code.WriteByte(opcode)
writeModTo(code, ModReg, i.ro, byte(reg))
imm.writeTo(code)
}
func writePrefixRegInsnTo(code gen.OpCoder, p prefix, t types.T, opcode []byte, ro, rm byte) {
if opcode == nil {
panic("instruction not supported")
}
p.writeTo(code, t, ro, 0, rm)
code.Write(opcode)
writeModTo(code, ModReg, ro, rm)
}
func writePrefixStackInsnTo(code gen.OpCoder, p prefix, t types.T, opcode []byte, reg regs.R, disp int32) {
mod, imm := dispMod(t, regStackPtr, disp)
p.writeTo(code, t, byte(reg), 0, 0)
code.Write(opcode)
writeModTo(code, mod, byte(reg), MemSIB)
writeSibTo(code, 0, regStackPtr, regStackPtr)
imm.writeTo(code)
}
func (i insnRexM) opStack(code gen.OpCoder, t types.T, disp int32) {
mod, imm := dispMod(t, regStackPtr, disp)
writeRexSizeTo(code, t, 0, 0, 0)
code.Write(i.opcode)
writeModTo(code, mod, i.ro, MemSIB)
writeSibTo(code, 0, regStackPtr, regStackPtr)
imm.writeTo(code)
}
func (i insnAddr32) op(code gen.OpCoder, addr int32) {
var offset int32
if addr != 0 {
siteAddr := code.Len() + i.size()
offset = addr - siteAddr
} else {
offset = -i.size() // infinite loop as placeholder
}
i.writeTo(code, offset)
}
func writePrefixAddrInsnTo(code gen.OpCoder, p prefix, t types.T, opcode []byte, reg regs.R, scale uint8, index regs.R, addr int32) {
if opcode == nil {
panic("instruction not supported")
}
p.writeTo(code, t, byte(reg), 0, 0)
code.Write(opcode)
writeModTo(code, ModMem, byte(reg), MemSIB)
writeSibTo(code, scale, index, NoBase)
writeInt32To(code, addr)
}
func (i insnPrefixMI) opImmToStack(code gen.OpCoder, t types.T, disp, value int32) {
mod, immDisp := dispMod(t, regStackPtr, disp)
opcode, immValue := i.immOpcode(value)
i.prefix.writeTo(code, t, 0, 0, 0)
code.WriteByte(opcode)
writeModTo(code, mod, i.ro, MemSIB)
writeSibTo(code, 0, regStackPtr, regStackPtr)
immDisp.writeTo(code)
immValue.writeTo(code)
}
func (p *floatSizePrefix) writeTo(code gen.OpCoder, t types.T, ro, index, rmOrBase byte) {
switch t.Size() {
case types.Size32:
code.Write(p.size32)
case types.Size64:
code.Write(p.size64)
default:
panic(t)
}
writeRexTo(code, 0, ro, index, rmOrBase)
}
func (i insnRexM) opIndirect(code gen.OpCoder, t types.T, reg regs.R, disp int32) {
mod, imm := dispMod(t, reg, disp)
writeRexSizeTo(code, t, 0, 0, byte(reg))
code.Write(i.opcode)
if reg != 12 {
writeModTo(code, mod, i.ro, byte(reg))
} else {
writeModTo(code, mod, i.ro, MemSIB)
writeSibTo(code, 0, NoIndex, reg)
}
imm.writeTo(code)
}
func writeRexTo(code gen.OpCoder, rex, ro, index, rmOrBase byte) {
if ro >= 8 {
rex |= rexR
}
if index >= 8 {
rex |= rexX
}
if rmOrBase >= 8 {
rex |= rexB
}
if rex != 0 {
code.WriteByte(rex)
}
}
func (i insnPrefixMI) opImmToIndirect(code gen.OpCoder, t types.T, scale uint8, index, base regs.R, disp, value int32) {
mod, immDisp := dispMod(t, base, disp)
opcode, immValue := i.immOpcode(value)
i.prefix.writeTo(code, t, 0, byte(index), byte(base))
code.WriteByte(opcode)
if scale == 0 && index == NoIndex && base != 12 {
writeModTo(code, mod, i.ro, byte(base))
} else {
writeModTo(code, mod, i.ro, MemSIB)
writeSibTo(code, scale, index, base)
}
immDisp.writeTo(code)
immValue.writeTo(code)
}
func writePrefixIndirectInsnTo(code gen.OpCoder, p prefix, t types.T, opcode []byte, reg regs.R, scale uint8, index, base regs.R, disp int32) {
if opcode == nil {
panic("instruction not supported")
}
mod, imm := dispMod(t, base, disp)
p.writeTo(code, t, byte(reg), byte(index), byte(base))
code.Write(opcode)
if scale == 0 && index == NoIndex && base != 12 {
writeModTo(code, mod, byte(reg), byte(base))
} else {
writeModTo(code, mod, byte(reg), MemSIB)
writeSibTo(code, scale, index, base)
}
imm.writeTo(code)
}
func (opcode insnAddr8) op(code gen.OpCoder, addr int32) (ok bool) {
insnSize := int32(len(opcode)) + 1
siteAddr := code.Len() + insnSize
offset := addr - siteAddr
if offset >= -0x80 && offset < 0x80 {
code.Write(opcode)
code.WriteByte(uint8(offset))
ok = true
}
return
}
// UpdateCalls modifies CallRel instructions, possibly while they are being
// executed.
func (mach X86) UpdateCalls(code gen.OpCoder, l *links.L) {
funcAddr := l.FinalAddr()
for _, retAddr := range l.Sites {
mach.PutUint32(code.Bytes()[retAddr-4:retAddr], uint32(funcAddr-retAddr))
}
}
func (i insnRexOM) opReg(code gen.OpCoder, reg regs.R) {
writeRexTo(code, 0, 0, 0, byte(reg))
code.Write(i.opcode)
writeModTo(code, ModReg, i.ro, byte(reg))
}
func (mach X86) updateAddr32(code gen.OpCoder, addr, value int32) {
binary.LittleEndian.PutUint32(code.Bytes()[addr-4:addr], uint32(value))
}
func (mach X86) updateAddr8(code gen.OpCoder, addr, value int32) {
if value < -0x80 || value >= 0x80 {
panic(value)
}
code.Bytes()[addr-1] = uint8(value)
}
func writeModTo(code gen.OpCoder, mod mod, ro, rm byte) {
code.WriteByte(byte(mod) | ((ro & 7) << 3) | (rm & 7))
}
func (mach X86) OpInit(code gen.OpCoder, startAddr int32) (retAddr int32) {
if code.Len() == 0 || code.Len() > functionAlignment {
panic("inconsistency")
}
code.Align(functionAlignment, paddingByte)
Add.opImm(code, types.I64, regStackLimit, gen.StackReserve)
var notResume links.L
Test.opFromReg(code, types.I64, regResult, regResult)
Je.rel8.opStub(code)
notResume.AddSite(code.Len())
Ret.op(code) // simulate return from snapshot function call
notResume.Addr = code.Len()
mach.updateBranches8(code, ¬Resume)
CallRel.op(code, startAddr)
return code.Len()
}
func (i insnRexM) opReg(code gen.OpCoder, t types.T, reg regs.R) {
writeRexSizeTo(code, t, 0, 0, byte(reg))
code.Write(i.opcode)
writeModTo(code, ModReg, i.ro, byte(reg))
}
func (i insnSuffixRMI) opReg(code gen.OpCoder, t types.T, target, source regs.R, value int8) {
code.Write(i.opcode)
i.suffix.writeTo(code, t, byte(target), 0, byte(source))
writeModTo(code, ModReg, byte(target), byte(source))
code.WriteByte(uint8(value))
}
func (i insnPrefixMI) opImm8(code gen.OpCoder, t types.T, reg regs.R, value uint8) {
i.prefix.writeTo(code, t, 0, 0, byte(reg))
code.WriteByte(i.opcode8)
writeModTo(code, ModReg, i.ro, byte(reg))
code.WriteByte(value)
}
func (opcode insnRex) op(code gen.OpCoder, t types.T) {
writeRexSizeTo(code, t, 0, 0, 0)
code.Write(opcode)
}
func (i insnRexOI) op(code gen.OpCoder, t types.T, reg regs.R, imm imm) {
writeRexSizeTo(code, t, 0, 0, byte(reg))
code.WriteByte(i.opbase + (byte(reg) & 7))
imm.writeTo(code)
}
func (i insnPrefixRexRM) opReg(code gen.OpCoder, floatType, intType types.T, target, source regs.R) {
i.prefix.writeTo(code, floatType, 0, 0, 0)
writeRexSizeTo(code, intType, byte(target), 0, byte(source))
code.Write(i.opcode)
writeModTo(code, ModReg, byte(target), byte(source))
}
func (i insnAddr8) opStub(code gen.OpCoder) {
i.op(code, code.Len()) // infinite loop as placeholder
}
func (opcode insnAddr32) writeTo(code gen.OpCoder, offset int32) {
code.Write(opcode)
writeInt32To(code, int32(offset))
}
func (i insnAddr32) opMissingFunction(code gen.OpCoder) {
siteAddr := code.Len() + i.size()
i.writeTo(code, -siteAddr)
}