// opBorrowMaybeResultReg returns either the register of the given operand, or
// the reserved result register with the value of the operand.
func (mach X86) opBorrowMaybeResultReg(code gen.RegCoder, x values.Operand, preserveFlags bool) (reg regs.R, zeroExt, own bool) {
if x.Storage == values.VarReg {
reg = x.Reg()
zeroExt = x.RegZeroExt()
} else {
reg, zeroExt = mach.opMaybeResultReg(code, x, preserveFlags)
own = (reg != regResult)
}
return
}
// opBorrowMaybeScratchReg returns either the register of the given operand, or
// the reserved scratch register with the value of the operand.
func (mach X86) opBorrowMaybeScratchReg(code gen.Coder, x values.Operand, preserveFlags bool) (reg regs.R, zeroExt, own bool) {
if x.Storage.IsReg() {
reg = x.Reg()
zeroExt = x.RegZeroExt()
} else {
reg = regScratch
zeroExt = mach.OpMove(code, reg, x, preserveFlags)
}
own = (x.Storage == values.TempReg)
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
}
// OpMove must not update CPU's condition flags if preserveFlags is set.
//
// X86 implementation note: must not blindly rely on regScratch or regResult in
// this function because we may be moving to one of them.
func (mach X86) OpMove(code gen.Coder, targetReg regs.R, x values.Operand, preserveFlags bool) (zeroExt bool) {
switch x.Type.Category() {
case types.Int:
switch x.Storage {
case values.Imm:
if value := x.ImmValue(); value == 0 && !preserveFlags {
Xor.opFromReg(code, types.I32, targetReg, targetReg)
} else {
MovImm64.op(code, x.Type, targetReg, value)
}
zeroExt = true
case values.VarMem:
Mov.opFromStack(code, x.Type, targetReg, x.VarMemOffset())
zeroExt = true
case values.VarReg:
if sourceReg := x.Reg(); sourceReg != targetReg {
Mov.opFromReg(code, x.Type, targetReg, sourceReg)
zeroExt = true
}
case values.TempReg:
if sourceReg := x.Reg(); sourceReg != targetReg {
Mov.opFromReg(code, x.Type, targetReg, sourceReg)
zeroExt = true
} else if targetReg == regResult {
zeroExt = x.RegZeroExt()
} else {
panic("moving temporary integer register to itself")
}
case values.Stack:
Pop.op(code, targetReg)
case values.ConditionFlags:
if x.Type != types.I32 {
panic(x)
}
var end links.L
cond := x.Condition()
setcc := conditionInsns[cond].setcc
switch {
case cond >= values.MinUnorderedOrCondition:
MovImm.opImm(code, x.Type, targetReg, 1) // true
Jp.rel8.opStub(code) // if unordered, else
end.AddSite(code.Len()) //
setcc.opReg(code, targetReg) // cond
case cond >= values.MinOrderedAndCondition:
MovImm.opImm(code, x.Type, targetReg, 0) // false
Jp.rel8.opStub(code) // if unordered, else
end.AddSite(code.Len()) //
setcc.opReg(code, targetReg) // cond
default:
setcc.opReg(code, targetReg)
Movzx8.opFromReg(code, x.Type, targetReg, targetReg)
}
end.Addr = code.Len()
mach.updateBranches8(code, &end)
zeroExt = true
default:
panic(x)
}
case types.Float:
switch x.Storage {
case values.Imm:
if value := x.ImmValue(); value == 0 {
PxorSSE.opFromReg(code, x.Type, targetReg, targetReg)
} else {
MovImm64.op(code, x.Type, regScratch, value) // integer scratch register
MovSSE.opFromReg(code, x.Type, targetReg, regScratch)
}
case values.VarMem:
MovsSSE.opFromStack(code, x.Type, targetReg, x.VarMemOffset())
case values.VarReg:
if sourceReg := x.Reg(); sourceReg != targetReg {
MovsSSE.opFromReg(code, x.Type, targetReg, sourceReg)
}
case values.TempReg:
if sourceReg := x.Reg(); sourceReg != targetReg {
MovsSSE.opFromReg(code, x.Type, targetReg, sourceReg)
} else if targetReg != regResult {
panic("moving temporary float register to itself")
}
case values.Stack:
popFloatOp(code, x.Type, targetReg)
default:
panic(x)
}
default:
panic(x)
}
code.Consumed(x)
return
}