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) 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
Cmp.opImm(code, t, b.Reg(), -1)
Je.rel8.opStub(code)
doNot.AddSite(code.Len())
} else {
switch t.Size() {
case types.Size32:
Cmp.opImm(code, t, regResult, -0x80000000)
case types.Size64:
MovImm64.op(code, t, regScratch, -0x8000000000000000)
Cmp.opFromReg(code, t, regResult, regScratch)
default:
panic(a)
}
Jne.rel8.opStub(code)
do.AddSite(code.Len())
Cmp.opImm(code, t, b.Reg(), -1)
Jne.rel8.opStub(code)
do.AddSite(code.Len())
code.OpTrapCall(traps.IntegerOverflow)
}
do.Addr = code.Len()
mach.updateBranches8(code, &do)
}
if signed {
// sign-extend dividend low bits to high bits
CdqCqo.op(code, t)
} else {
// zero-extend dividend high bits
Xor.opFromReg(code, types.I32, regScratch, regScratch)
}
}
insn.opReg(code, t, b.Reg())
code.Consumed(b)
doNot.Addr = code.Len()
mach.updateBranches8(code, &doNot)
if remainder {
Mov.opFromReg(code, t, regResult, regScratch)
}
return values.TempRegOperand(t, regResult, true)
}
// 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
}
Lea.opFromIndirect(code, types.I64, regScratch, 0, reg, regMemoryBase, int32(reachOffset))
if own {
code.FreeReg(types.I32, reg)
}
}
Cmp.opFromReg(code, types.I64, regScratch, regMemoryLimit)
if addr := code.TrapTrampolineAddr(traps.MemoryOutOfBounds); addr != 0 {
Jge.op(code, addr)
} else {
var checked links.L
Jl.rel8.opStub(code)
checked.AddSite(code.Len())
code.OpTrapCall(traps.MemoryOutOfBounds)
checked.Addr = code.Len()
mach.updateBranches8(code, &checked)
}
baseReg = regScratch
indexReg = NoIndex
disp = -int32(sizeReach)
return
}
func (mach X86) OpCurrentMemory(code gen.RegCoder) values.Operand {
Mov.opFromReg(code, types.I64, regResult, regMemoryLimit)
Sub.opFromReg(code, types.I64, regResult, regMemoryBase)
ShrImm.op(code, types.I64, regResult, wasm.PageBits)
return values.TempRegOperand(types.I32, regResult, true)
}
func (mach X86) OpGrowMemory(code gen.RegCoder, x values.Operand) values.Operand {
var out links.L
var fail links.L
MovMMX.opToReg(code, types.I64, regScratch, regMemoryGrowLimitMMX)
targetReg, zeroExt := mach.opMaybeResultReg(code, x, false)
if !zeroExt {
Mov.opFromReg(code, types.I32, targetReg, targetReg)
}
ShlImm.op(code, types.I64, targetReg, wasm.PageBits)
Add.opFromReg(code, types.I64, targetReg, regMemoryLimit) // new memory limit
Cmp.opFromReg(code, types.I64, targetReg, regScratch)
Jg.rel8.opStub(code)
fail.AddSite(code.Len())
Mov.opFromReg(code, types.I64, regScratch, regMemoryLimit)
Mov.opFromReg(code, types.I64, regMemoryLimit, targetReg)
Sub.opFromReg(code, types.I64, regScratch, regMemoryBase)
ShrImm.op(code, types.I64, regScratch, wasm.PageBits) // value on success
Mov.opFromReg(code, types.I32, targetReg, regScratch)
JmpRel.rel8.opStub(code)
out.AddSite(code.Len())
fail.Addr = code.Len()
mach.updateBranches8(code, &fail)
MovImm.opImm(code, types.I32, targetReg, -1) // value on failure
out.Addr = code.Len()
mach.updateBranches8(code, &out)
return values.TempRegOperand(types.I32, targetReg, true)
}