/*
* users should call the integerSubtractAnalyser or integerSubtractAnalyserWithExplicitOperands APIs instead of calling this one directly
*/
TR::Register* TR_X86SubtractAnalyser::integerSubtractAnalyserImpl(TR::Node *root,
TR::Node *firstChild,
TR::Node *secondChild,
TR_X86OpCodes regRegOpCode,
TR_X86OpCodes regMemOpCode,
TR_X86OpCodes copyOpCode,
bool needsEflags,
TR::Node *borrow)
{
TR::Register *targetRegister = NULL;
TR::Register *firstRegister = firstChild->getRegister();
TR::Register *secondRegister = secondChild->getRegister();
setInputs(firstChild, firstRegister, secondChild, secondRegister);
bool loadedConst = false;
needsEflags = needsEflags || NEED_CC(root);
if (getEvalChild1())
{
// if firstChild and secondChild are the same node, then we should
// evaluate (take the else path) so that the evaluate for the secondChild
// below will get the correct/already-allocated register.
if (firstRegister == 0 && firstChild->getOpCodeValue() == TR::iconst && (firstChild != secondChild))
{
// An iconst may have to be generated. The iconst will be generated after the
// secondChild is evaluated. Set the loadedConst flag to true.
loadedConst = true;
}
else
{
firstRegister = _cg->evaluate(firstChild);
}
}
if (getEvalChild2())
{
secondRegister = _cg->evaluate(secondChild);
if (firstChild->getRegister())
{
firstRegister = firstChild->getRegister();
}
else if (!loadedConst)
{
firstRegister = _cg->evaluate(firstChild);
}
}
if (loadedConst)
{
if (firstRegister == 0)
{
// firstchild is an inconst and it has not been evaluated.
// Generate the code for an iconst.
firstRegister = _cg->allocateRegister();
TR::TreeEvaluator::insertLoadConstant(firstChild, firstRegister, firstChild->getInt(), TR_RematerializableInt, _cg);
}
else
{
// firstchild was evaluated. The code for an iconst does not need to be generated.
// Set the loadConst flag to false.
loadedConst = false;
}
}
if (borrow != 0)
TR_X86ComputeCC::setCarryBorrow(borrow, true, _cg);
if (getCopyReg1())
{
if (firstChild->getReferenceCount() > 1)
{
TR::Register *thirdReg;
if (firstChild->getOpCodeValue() == TR::iconst && loadedConst)
{
thirdReg = firstRegister;
}
else
{
if (secondChild->getReferenceCount() == 1 && secondRegister != 0 && !needsEflags && (borrow == 0))
{
// use one fewer registers if we negate the clobberable secondRegister and add
// Don't do this though if condition codes are needed. The sequence
// depends on the carry flag being valid as if a sub was done.
//
bool nodeIs64Bit = TR_X86OpCode(regRegOpCode).hasLongSource();
generateRegInstruction(NEGReg(nodeIs64Bit), secondChild, secondRegister, _cg);
thirdReg = secondRegister;
secondRegister = firstRegister;
regRegOpCode = ADDRegReg(nodeIs64Bit);
}
else
{
thirdReg = _cg->allocateRegister();
generateRegRegInstruction(copyOpCode, root, thirdReg, firstRegister, _cg);
}
}
targetRegister = thirdReg;
if (getSubReg3Reg2())
{
generateRegRegInstruction(regRegOpCode, root, thirdReg, secondRegister, _cg);
}
else // assert getSubReg3Mem2() == true
{
TR::MemoryReference *tempMR = generateX86MemoryReference(secondChild, _cg);
generateRegMemInstruction(regMemOpCode, root, thirdReg, tempMR, _cg);
tempMR->decNodeReferenceCounts(_cg);
}
}
else
{
if (getSubReg3Reg2())
{
generateRegRegInstruction(regRegOpCode, root, firstRegister, secondRegister, _cg);
}
else // assert getSubReg3Mem2() == true
{
TR::MemoryReference *tempMR = generateX86MemoryReference(secondChild, _cg);
generateRegMemInstruction(regMemOpCode, root, firstRegister, tempMR, _cg);
tempMR->decNodeReferenceCounts(_cg);
}
targetRegister = firstRegister;
}
}
else if (getSubReg1Reg2())
{
generateRegRegInstruction(regRegOpCode, root, firstRegister, secondRegister, _cg);
targetRegister = firstRegister;
}
else // assert getSubReg1Mem2() == true
{
TR::MemoryReference *tempMR = generateX86MemoryReference(secondChild, _cg);
generateRegMemInstruction(regMemOpCode, root, firstRegister, tempMR, _cg);
targetRegister = firstRegister;
tempMR->decNodeReferenceCounts(_cg);
}
return targetRegister;
}
extern TR_X86OpCodes ADDRegReg() { return ADDRegReg ( TR::Compiler->target.is64Bit() ? true : false ); }