func (mach X86) binaryIntCompareOp(code gen.RegCoder, cond uint8, a, b values.Operand) (result values.Operand) {
	result = values.ConditionFlagsOperand(values.Condition(cond))

	targetReg, _, own := mach.opBorrowMaybeResultReg(code, a, false)
	if own {
		defer code.FreeReg(a.Type, targetReg)
	}

	if b.Storage == values.VarMem {
		Cmp.opFromStack(code, a.Type, targetReg, b.VarMemOffset())
		return
	}

	var sourceReg regs.R

	if b.Storage.IsReg() {
		sourceReg = b.Reg()
	} else {
		if b.Storage == values.Imm {
			if value := b.ImmValue(); value >= -0x80000000 && value < 0x80000000 {
				Cmp.opImm(code, a.Type, targetReg, int32(value))
				return
			}
		}
		sourceReg = regScratch
		mach.OpMove(code, sourceReg, b, false)
	}

	Cmp.opFromReg(code, a.Type, targetReg, sourceReg)
	code.Consumed(b)
	return
}

// LoadOp makes sure that index gets zero-extended if it's a VarReg operand.
func (mach X86) LoadOp(code gen.RegCoder, oper uint16, index values.Operand, resultType types.T, offset uint32) (result values.Operand) {
	size := oper >> 8

	baseReg, indexReg, ownIndexReg, disp := mach.opMemoryAddress(code, size, index, offset)
	if ownIndexReg {
		defer code.FreeReg(types.I64, indexReg)
	}

	load := memoryLoads[uint8(oper)]

	targetReg, ok := code.TryAllocReg(resultType)
	if !ok {
		targetReg = regResult
	}

	result = values.TempRegOperand(resultType, targetReg, load.zeroExt)

	insnType := load.insnType
	if insnType == 0 {
		insnType = resultType
	}

	load.insn.opFromIndirect(code, insnType, targetReg, 0, indexReg, baseReg, disp)
	return
}

func (mach X86) binaryFloatOp(code gen.RegCoder, index uint8, a, b values.Operand) values.Operand {
	targetReg, _ := mach.opMaybeResultReg(code, a, false)

	sourceReg, _, own := mach.opBorrowMaybeScratchReg(code, b, false)
	if own {
		defer code.FreeReg(b.Type, sourceReg)
	}

	binaryFloatInsns[index].opFromReg(code, a.Type, targetReg, sourceReg)
	return values.TempRegOperand(a.Type, targetReg, false)
}

// OpGetGlobal must not update CPU's condition flags.
func (mach X86) OpGetGlobal(code gen.RegCoder, t types.T, offset int32) values.Operand {
	reg, ok := code.TryAllocReg(t)
	if !ok {
		reg = regResult
	}

	if t.Category() == types.Int {
		Mov.opFromIndirect(code, t, reg, 0, NoIndex, regMemoryBase, offset)
	} else {
		MovSSE.opFromIndirect(code, t, reg, 0, NoIndex, regMemoryBase, offset)
	}

	return values.TempRegOperand(t, reg, true)
}

func (mach X86) binaryFloatCompareOp(code gen.RegCoder, cond uint8, a, b values.Operand) values.Operand {
	aReg, _, own := mach.opBorrowMaybeResultReg(code, a, true)
	if own {
		defer code.FreeReg(a.Type, aReg)
	}

	bReg, _, own := mach.opBorrowMaybeScratchReg(code, b, false)
	if own {
		defer code.FreeReg(b.Type, bReg)
	}

	UcomisSSE.opFromReg(code, a.Type, aReg, bReg)
	return values.ConditionFlagsOperand(values.Condition(cond))
}

func (mach X86) unaryIntOp(code gen.RegCoder, index uint8, x values.Operand) (result values.Operand) {
	if index == opers.IndexIntEqz {
		reg, _, own := mach.opBorrowMaybeScratchReg(code, x, false)
		if own {
			defer code.FreeReg(x.Type, reg)
		}

		Test.opFromReg(code, x.Type, reg, reg)
		return values.ConditionFlagsOperand(values.Eq)
	}

	var targetReg regs.R

	sourceReg, _, own := mach.opBorrowMaybeScratchReg(code, x, false)
	if own {
		targetReg = sourceReg
	} else {
		var ok bool

		targetReg, ok = code.TryAllocReg(x.Type)
		if !ok {
			targetReg = regResult
		}
	}

	result = values.TempRegOperand(x.Type, targetReg, true)

	insn := unaryIntInsns[index]

	switch index {
	case opers.IndexIntClz:
		insn.opFromReg(code, x.Type, regScratch, sourceReg)
		MovImm.opImm(code, x.Type, targetReg, -1)
		Cmove.opFromReg(code, x.Type, regScratch, targetReg)
		MovImm.opImm(code, x.Type, targetReg, (int32(x.Type.Size())<<3)-1)
		Sub.opFromReg(code, x.Type, targetReg, regScratch)

	case opers.IndexIntCtz:
		insn.opFromReg(code, x.Type, targetReg, sourceReg)
		MovImm.opImm(code, x.Type, regScratch, int32(x.Type.Size())<<3)
		Cmove.opFromReg(code, x.Type, targetReg, regScratch)

	case opers.IndexIntPopcnt:
		insn.opFromReg(code, x.Type, targetReg, sourceReg)
	}

	return
}

// opMaybeResultReg returns either the register of the given operand, or the
// reserved result register with the value of the operand.  The caller has
// exclusive ownership of the register.
func (mach X86) opMaybeResultReg(code gen.RegCoder, x values.Operand, preserveFlags bool) (reg regs.R, zeroExt bool) {
	if x.Storage == values.TempReg {
		reg = x.Reg()
		zeroExt = x.RegZeroExt()
	} else {
		var ok bool

		reg, ok = code.TryAllocReg(x.Type)
		if !ok {
			reg = regResult
		}

		if x.Storage != values.Nowhere {
			mach.OpMove(code, reg, x, preserveFlags)
			zeroExt = true
		}
	}
	return
}

func (mach X86) binaryShiftOp(code gen.RegCoder, index uint8, a, b values.Operand) values.Operand {
	insn := binaryShiftInsns[index]

	var targetReg regs.R

	switch b.Storage {
	case values.Imm:
		targetReg, _ = mach.opMaybeResultReg(code, a, true)
		insn.imm.op(code, b.Type, targetReg, uint8(b.ImmValue()))

	default:
		if b.Storage.IsReg() && b.Reg() == regShiftCount {
			targetReg, _ = mach.opMaybeResultReg(code, a, false)
			defer code.Discard(b)
		} else {
			if code.RegAllocated(types.I32, regShiftCount) {
				targetReg, _ = mach.opMaybeResultReg(code, a, true)
				if targetReg == regShiftCount {
					Mov.opFromReg(code, a.Type, regResult, regShiftCount)
					targetReg = regResult

					defer code.FreeReg(types.I32, regShiftCount)
				} else {
					// unknown operand in regShiftCount
					Mov.opFromReg(code, types.I64, regScratch, regShiftCount)
					defer Mov.opFromReg(code, types.I64, regShiftCount, regScratch)
				}
			} else {
				code.AllocSpecificReg(types.I32, regShiftCount)
				defer code.FreeReg(types.I32, regShiftCount)

				targetReg, _ = mach.opMaybeResultReg(code, a, true)
			}

			b.Type = types.I32 // TODO: 8-bit mov
			mach.OpMove(code, regShiftCount, b, false)
		}

		insn.opReg(code, a.Type, targetReg)
	}

	return values.TempRegOperand(a.Type, targetReg, true)
}

func (mach X86) ConversionOp(code gen.RegCoder, oper uint16, resultType types.T, source values.Operand) (result values.Operand) {
	if oper == opers.Wrap {
		source.Type = types.I32 // short mov; useful zeroExt flag
		reg, zeroExt := mach.opMaybeResultReg(code, source, false)
		return values.TempRegOperand(resultType, reg, zeroExt)
	}

	reg, zeroExt := mach.opMaybeResultReg(code, source, false)
	// TODO: for int<->float ops: borrow source reg, allocate target reg

	switch oper {
	case opers.ExtendS:
		Movsxd.opFromReg(code, 0, reg, reg)
		result = values.TempRegOperand(resultType, reg, false)

	case opers.ExtendU:
		if !zeroExt {
			Mov.opFromReg(code, types.I32, reg, reg)
		}
		result = values.TempRegOperand(resultType, reg, false)

	case opers.Mote:
		Cvts2sSSE.opFromReg(code, source.Type, reg, reg)
		result = values.TempRegOperand(resultType, reg, false)

	case opers.TruncS:
		panic(fmt.Errorf("%s.trunc_s/%s not implemented", resultType, source.Type))

	case opers.TruncU:
		panic(fmt.Errorf("%s.trunc_u/%s not implemented", resultType, source.Type))

	case opers.ConvertS:
		Cvtsi2sSSE.opReg(code, resultType, source.Type, regResult, reg)
		code.FreeReg(source.Type, reg)
		result = values.TempRegOperand(resultType, regResult, false)

	case opers.ConvertU:
		if source.Type == types.I32 {
			if !zeroExt {
				Mov.opFromReg(code, types.I32, reg, reg)
			}
			Cvtsi2sSSE.opReg(code, resultType, types.I64, regResult, reg)
		} else {
			mach.opConvertUnsignedI64ToFloat(code, resultType, reg)
		}
		code.FreeReg(source.Type, reg)
		result = values.TempRegOperand(resultType, regResult, false)

	case opers.Reinterpret:
		if source.Type.Category() == types.Int {
			MovSSE.opFromReg(code, source.Type, regResult, reg)
		} else {
			MovSSE.opToReg(code, source.Type, regResult, reg)
		}
		code.FreeReg(source.Type, reg)
		result = values.TempRegOperand(resultType, regResult, true)
	}

	return
}

func (mach X86) opCheckDivideByZero(code gen.RegCoder, t types.T, reg regs.R) {
	var end links.L

	Test.opFromReg(code, t, reg, reg)
	Jne.rel8.opStub(code)
	end.AddSite(code.Len())

	code.OpTrapCall(traps.IntegerDivideByZero)

	end.Addr = code.Len()
	mach.updateBranches8(code, &end)
}

func (mach X86) OpSelect(code gen.RegCoder, a, b, condOperand values.Operand) values.Operand {
	defer code.Consumed(condOperand)

	var cond values.Condition

	switch condOperand.Storage {
	case values.VarMem:
		Cmp.opImmToStack(code, types.I32, condOperand.VarMemOffset(), 0)
		cond = values.Ne

	case values.VarReg, values.TempReg:
		reg := condOperand.Reg()
		Test.opFromReg(code, types.I32, reg, reg)
		cond = values.Ne

	case values.Stack:
		mach.OpAddImmToStackPtr(code, 8) // do before cmp to avoid overwriting flags
		Cmp.opImmToStack(code, types.I32, -8, 0)
		cond = values.Ne

	case values.ConditionFlags:
		cond = condOperand.Condition()

	case values.Imm:
		if condOperand.ImmValue() != 0 {
			code.Consumed(b)
			return a
		} else {
			code.Consumed(a)
			return b
		}

	default:
		panic(condOperand)
	}

	t := a.Type
	targetReg, _ := mach.opMaybeResultReg(code, b, true)

	switch t.Category() {
	case types.Int:
		cmov := conditionInsns[cond].cmov

		switch a.Storage {
		case values.VarMem:
			cmov.opFromStack(code, t, targetReg, a.VarMemOffset())

		default:
			aReg, _, own := mach.opBorrowMaybeScratchReg(code, a, true)
			if own {
				defer code.FreeReg(t, aReg)
			}

			cmov.opFromReg(code, t, targetReg, aReg)
		}

	case types.Float:
		var moveIt links.L
		var end links.L

		cond = values.InvertedConditions[cond]
		notCondJump := conditionInsns[cond].jcc

		switch {
		case cond >= values.MinUnorderedOrCondition:
			Jp.rel8.opStub(code) // move it if unordered
			moveIt.AddSite(code.Len())

			notCondJump.rel8.opStub(code) // break if not cond
			end.AddSite(code.Len())

		case cond >= values.MinOrderedAndCondition:
			Jp.rel8.opStub(code) // break if unordered
			end.AddSite(code.Len())

			notCondJump.rel8.opStub(code) // break if not cond
			end.AddSite(code.Len())

		default:
			notCondJump.rel8.opStub(code) // break if not cond
			end.AddSite(code.Len())
		}

		moveIt.Addr = code.Len()
		mach.updateBranches8(code, &moveIt)

		mach.OpMove(code, targetReg, a, false)

		end.Addr = code.Len()
		mach.updateBranches8(code, &end)

	default:
		panic(t)
	}

	// cmov zero-extends the target unconditionally
	return values.TempRegOperand(t, targetReg, true)
}

func (mach X86) binaryIntOp(code gen.RegCoder, index uint8, a, b values.Operand) (result values.Operand) {
	if a.Storage == values.Imm && a.ImmValue() == 0 && index == opers.IndexIntSub {
		targetReg, _ := mach.opMaybeResultReg(code, b, false)
		Neg.opReg(code, a.Type, targetReg)
		return values.TempRegOperand(a.Type, targetReg, true)
	}

	switch b.Storage {
	case values.Imm:
		value := b.ImmValue()

		switch {
		case index == opers.IndexIntAdd && value == 1: // assume that we won't see sub -1
			reg, _ := mach.opMaybeResultReg(code, a, false)
			Inc.opReg(code, a.Type, reg)
			return values.TempRegOperand(a.Type, reg, true)

		case index == opers.IndexIntSub && value == 1: // assume that we won't see add -1
			reg, _ := mach.opMaybeResultReg(code, a, false)
			Dec.opReg(code, a.Type, reg)
			return values.TempRegOperand(a.Type, reg, true)

		case value < -0x80000000 || value >= 0x80000000:
			// TODO: merge this with the next outer case
			sourceReg, _, own := mach.opBorrowMaybeScratchReg(code, b, true)
			b = values.RegOperand(own, a.Type, sourceReg)
		}

	case values.Stack, values.ConditionFlags:
		sourceReg, _, own := mach.opBorrowMaybeScratchReg(code, b, true)
		b = values.RegOperand(own, a.Type, sourceReg)
	}

	insn := binaryIntInsns[index]
	targetReg, _ := mach.opMaybeResultReg(code, a, false)
	result = values.TempRegOperand(a.Type, targetReg, true)

	if b.Storage == values.VarMem {
		insn.opFromStack(code, a.Type, targetReg, b.VarMemOffset())
		return
	}

	var sourceReg regs.R

	if b.Storage.IsReg() {
		sourceReg = b.Reg()
	} else {
		if b.Storage == values.Imm {
			if value := b.ImmValue(); value >= -0x80000000 && value < 0x80000000 {
				insn.opImm(code, a.Type, targetReg, int32(b.ImmValue()))
				return
			}
		}
		sourceReg = regScratch
		mach.OpMove(code, sourceReg, b, false)
	}

	insn.opFromReg(code, a.Type, targetReg, sourceReg)
	code.Consumed(b)
	return
}

func (mach X86) binaryDivmulOp(code gen.RegCoder, index uint8, a, b values.Operand) values.Operand {
	insn := binaryDivmulInsns[index]
	t := a.Type

	if b.Storage == values.Imm {
		value := b.ImmValue()

		switch {
		case value == -1:
			reg, _ := mach.opMaybeResultReg(code, a, false)
			Neg.opReg(code, t, reg)
			return values.TempRegOperand(t, reg, true)

		case insn.shiftImm.defined() && value > 0 && isPowerOfTwo(uint64(value)):
			reg, _ := mach.opMaybeResultReg(code, a, false)
			insn.shiftImm.op(code, t, reg, log2(uint64(value)))
			return values.TempRegOperand(t, reg, true)
		}
	}

	division := (index & opers.DivmulMul) == 0
	checkZero := true
	checkOverflow := true

	if b.Storage.IsReg() {
		if b.Reg() == regResult {
			newReg := regScratch

			if division {
				var ok bool

				// can't use scratch reg as divisor since it contains the dividend high bits
				newReg, ok = code.TryAllocReg(t)
				if !ok {
					// borrow a register which we don't need in this function
					MovMMX.opFromReg(code, types.I64, regScratchMMX, regTextBase)
					defer MovMMX.opToReg(code, types.I64, regTextBase, regScratchMMX)

					newReg = regTextBase
				}
			}

			Mov.opFromReg(code, t, newReg, regResult)
			b = values.RegOperand(true, t, newReg)
		}
	} else {
		if division && b.Storage == values.Imm {
			value := b.ImmValue()
			if value != 0 {
				checkZero = false
			}
			if value != -1 {
				checkOverflow = false
			}
		}

		reg, ok := code.TryAllocReg(t)
		if !ok {
			// borrow a register which we don't need in this function
			MovMMX.opFromReg(code, types.I64, regScratchMMX, regTextBase)
			defer MovMMX.opToReg(code, types.I64, regTextBase, regScratchMMX)

			reg = regTextBase
		}

		mach.OpMove(code, reg, b, true)
		b = values.RegOperand(true, t, reg)
	}

	mach.OpMove(code, regResult, a, false)

	remainder := (index & opers.DivmulRem) != 0

	var doNot links.L

	if division {
		if checkZero {
			mach.opCheckDivideByZero(code, t, b.Reg())
		}

		if a.Storage == values.Imm {
			value := a.ImmValue()
			if t.Size() == types.Size32 {
				if value != -0x80000000 {
					checkOverflow = false
				}
			} else {
				if value != -0x8000000000000000 {
					checkOverflow = false
				}
			}
		}

		signed := (index & opers.DivmulSign) != 0

		if signed && checkOverflow {
			var do links.L

			if remainder {
				Xor.opFromReg(code, types.I32, regScratch, regScratch) // moved to result at the end
//.........这里部分代码省略.........

// StoreOp makes sure that index gets zero-extended if it's a VarReg operand.
func (mach X86) StoreOp(code gen.RegCoder, oper uint16, index, x values.Operand, offset uint32) {
	size := oper >> 8

	baseReg, indexReg, ownIndexReg, disp := mach.opMemoryAddress(code, size, index, offset)
	if ownIndexReg {
		defer code.FreeReg(types.I64, indexReg)
	}

	store := memoryStores[uint8(oper)]

	insnType := store.insnType
	if insnType == 0 {
		insnType = x.Type
	}

	if x.Storage == values.Imm {
		value := x.ImmValue()
		value32 := int32(value)

		switch {
		case size == 1:
			value32 = int32(int8(value32))

		case size == 2:
			value32 = int32(int16(value32))

		case size == 4 || (value >= -0x80000000 && value < 0x80000000):

		default:
			goto large
		}

		store.insn.opImmToIndirect(code, insnType, 0, indexReg, baseReg, disp, value32)
		return

	large:
	}

	valueReg, _, own := mach.opBorrowMaybeResultReg(code, x, false)
	if own {
		defer code.FreeReg(x.Type, valueReg)
	}

	store.insn.opToIndirect(code, insnType, valueReg, 0, indexReg, baseReg, disp)
}

// opMemoryAddress may return the scratch register as the base.
func (mach X86) opMemoryAddress(code gen.RegCoder, size uint16, index values.Operand, offset uint32) (baseReg, indexReg regs.R, ownIndexReg bool, disp int32) {
	sizeReach := uint64(size - 1)
	reachOffset := uint64(offset) + sizeReach

	if reachOffset >= 0x80000000 {
		code.OpTrapCall(traps.MemoryOutOfBounds)
		return
	}

	alreadyChecked := reachOffset < uint64(index.Bounds.Upper)

	switch index.Storage {
	case values.Imm:
		value := uint64(index.ImmValue())

		if value >= 0x80000000 {
			code.OpTrapCall(traps.MemoryOutOfBounds)
			return
		}

		addr := value + uint64(offset)
		reachAddr := addr + sizeReach

		if reachAddr >= 0x80000000 {
			code.OpTrapCall(traps.MemoryOutOfBounds)
			return
		}

		if reachAddr < uint64(code.MinMemorySize()) || alreadyChecked {
			baseReg = regMemoryBase
			indexReg = NoIndex
			disp = int32(addr)
			return
		}

		Lea.opFromIndirect(code, types.I64, regScratch, 0, NoIndex, regMemoryBase, int32(reachAddr))

	default:
		reg, zeroExt, own := mach.opBorrowMaybeScratchReg(code, index, true)

		if !zeroExt {
			Mov.opFromReg(code, types.I32, reg, reg) // zero-extend index
		}

		if alreadyChecked {
			baseReg = regMemoryBase
			indexReg = reg
			ownIndexReg = own
			disp = int32(offset)
			return
		}

//.........这里部分代码省略.........