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Differential D24480 Diff 71070 lib/Transforms/InstCombine/InstCombineAddSub.cpp

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lib/Transforms/InstCombine/InstCombineAddSub.cpp

Show First 20 Lines • Show All 1,061 Lines • ▼ Show 20 LinesInstruction *InstCombiner::visitAdd(BinaryOperator &I) {
// FIXME: Use the match above instead of dyn_cast to allow these transforms // FIXME: Use the match above instead of dyn_cast to allow these transforms
// for splat vectors. // for splat vectors.
if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
// See if SimplifyDemandedBits can simplify this. This handles stuff like // See if SimplifyDemandedBits can simplify this. This handles stuff like
// (X & 254)+1 -> (X&254)|1 // (X & 254)+1 -> (X&254)|1
if (SimplifyDemandedInstructionBits(I)) if (SimplifyDemandedInstructionBits(I))
return &I; return &I;
// zext(bool) + C -> bool ? C + 1 : C // add (zext (icmp Pred X, Y)), -1 --> sext (icmp Pred' X, Y)
efriedmaUnsubmitted
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I guess we should prefer sext(cmp) over add(zext(cmp), -1), but we prefer add(zext(cmp), N) over add(sext(cmp), N-1) for any other N? That works, but you might want to explain that here.

efriedma: I guess we should prefer sext(cmp) over add(zext(cmp), -1), but we prefer add(zext(cmp), N)…
if (ZExtInst *ZI = dyn_cast<ZExtInst>(LHS)) Instruction *ZextOp;
if (ZI->getSrcTy()->isIntegerTy(1)) ICmpInst::Predicate Pred;
return SelectInst::Create(ZI->getOperand(0), AddOne(CI), CI); Value *X, *Y;
if (CI->getSExtValue() == -1 && match(LHS, m_ZExt(m_Instruction(ZextOp))) &&
match(ZextOp, m_OneUse(m_ICmp(Pred, m_Value(X), m_Value(Y))))) {
// We have this pattern: if the compare is true, return 0;
// if the compare is false, return -1.
// Transform it to: if the inverse compare is true, return -1;
// if the inverse compare is false, return 0.
auto *Cmp = Builder->CreateICmp(CmpInst::getInversePredicate(Pred), X, Y);
return CastInst::Create(Instruction::SExt, Cmp, I.getType());
}
Value *XorLHS = nullptr; ConstantInt *XorRHS = nullptr; Value *XorLHS = nullptr; ConstantInt *XorRHS = nullptr;
if (match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) { if (match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
uint32_t TySizeBits = I.getType()->getScalarSizeInBits(); uint32_t TySizeBits = I.getType()->getScalarSizeInBits();
const APInt &RHSVal = CI->getValue(); const APInt &RHSVal = CI->getValue();
unsigned ExtendAmt = 0; unsigned ExtendAmt = 0;
// If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext. // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
// If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext. // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
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