bool
CodeGeneratorX86Shared::visitOutOfLineUndoALUOperation(OutOfLineUndoALUOperation *ool)
{
LInstruction *ins = ool->ins();
Register reg = ToRegister(ins->getDef(0));
mozilla::DebugOnly<LAllocation *> lhs = ins->getOperand(0);
LAllocation *rhs = ins->getOperand(1);
JS_ASSERT(reg == ToRegister(lhs));
JS_ASSERT_IF(rhs->isGeneralReg(), reg != ToRegister(rhs));
// Undo the effect of the ALU operation, which was performed on the output
// register and overflowed. Writing to the output register clobbered an
// input reg, and the original value of the input needs to be recovered
// to satisfy the constraint imposed by any RECOVERED_INPUT operands to
// the bailout snapshot.
if (rhs->isConstant()) {
Imm32 constant(ToInt32(rhs));
if (ins->isAddI())
masm.subl(constant, reg);
else
masm.addl(constant, reg);
} else {
if (ins->isAddI())
masm.subl(ToOperand(rhs), reg);
else
masm.addl(ToOperand(rhs), reg);
}
return bailout(ool->ins()->snapshot());
}
bool
GreedyAllocator::prescanUses(LInstruction *ins)
{
for (size_t i = 0; i < ins->numOperands(); i++) {
LAllocation *a = ins->getOperand(i);
if (!a->isUse()) {
JS_ASSERT(a->isConstant());
continue;
}
LUse *use = a->toUse();
VirtualRegister *vr = getVirtualRegister(use);
if (use->policy() == LUse::FIXED) {
// A def or temp may use the same register, so we have to use the
// unchecked version.
disallowed.addUnchecked(GetFixedRegister(vr->def, use));
} else if (vr->hasRegister()) {
discouraged.addUnchecked(vr->reg());
}
}
return true;
}
