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[InstCombine] reduce code for signbit folds; NFC

This commit is contained in:
Sanjay Patel 2022-07-18 10:37:18 -04:00
parent c00a44fa68
commit 26fbb79c33
1 changed files with 12 additions and 14 deletions
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26
llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
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@ -3202,25 +3202,23 @@ Value *InstCombinerImpl::foldXorOfICmps(ICmpInst *LHS, ICmpInst *RHS,
// TODO: This can be generalized to compares of non-signbits using
// decomposeBitTestICmp(). It could be enhanced more by using (something like)
// foldLogOpOfMaskedICmps().
if ((LHS->hasOneUse() || RHS->hasOneUse()) &&
const APInt *LC, *RC;
if (match(LHS1, m_APInt(LC)) && match(RHS1, m_APInt(RC)) &&
LHS0->getType() == RHS0->getType() &&
LHS0->getType()->isIntOrIntVectorTy()) {
LHS0->getType()->isIntOrIntVectorTy() &&
(LHS->hasOneUse() || RHS->hasOneUse())) {
// Convert xor of signbit tests to signbit test of xor'd values:
// (X > -1) ^ (Y > -1) --> (X ^ Y) < 0
// (X < 0) ^ (Y < 0) --> (X ^ Y) < 0
if ((PredL == CmpInst::ICMP_SGT && match(LHS1, m_AllOnes()) &&
PredR == CmpInst::ICMP_SGT && match(RHS1, m_AllOnes())) ||
(PredL == CmpInst::ICMP_SLT && match(LHS1, m_Zero()) &&
PredR == CmpInst::ICMP_SLT && match(RHS1, m_Zero())))
return Builder.CreateIsNeg(Builder.CreateXor(LHS0, RHS0));
// (X > -1) ^ (Y < 0) --> (X ^ Y) > -1
// (X < 0) ^ (Y > -1) --> (X ^ Y) > -1
if ((PredL == CmpInst::ICMP_SGT && match(LHS1, m_AllOnes()) &&
PredR == CmpInst::ICMP_SLT && match(RHS1, m_Zero())) ||
(PredL == CmpInst::ICMP_SLT && match(LHS1, m_Zero()) &&
PredR == CmpInst::ICMP_SGT && match(RHS1, m_AllOnes())))
return Builder.CreateIsNotNeg(Builder.CreateXor(LHS0, RHS0));
bool TrueIfSignedL, TrueIfSignedR;
if (isSignBitCheck(PredL, *LC, TrueIfSignedL) &&
isSignBitCheck(PredR, *RC, TrueIfSignedR)) {
Value *XorLR = Builder.CreateXor(LHS0, RHS0);
return TrueIfSignedL == TrueIfSignedR ? Builder.CreateIsNeg(XorLR) :
Builder.CreateIsNotNeg(XorLR);
}
}
// Instead of trying to imitate the folds for and/or, decompose this 'xor'