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[NFC][InstCombine] Refactor '(-NSW x) pred x' fold

This commit is contained in:
Roman Lebedev 2020-08-06 11:34:03 +03:00
parent 141357663e
commit a512c89476
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GPG Key ID: 083C3EBB4A1689E0
1 changed files with 7 additions and 53 deletions
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60
llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
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@ -3725,60 +3725,14 @@ Instruction *foldICmpXNegX(ICmpInst &I) {
if (!match(&I, m_c_ICmp(Pred, m_NSWNeg(m_Value(X)), m_Deferred(X))))
return nullptr;
CmpInst::Predicate NewPred;
Constant *NewRHS;
switch (Pred) {
case ICmpInst::ICMP_SGT:
NewPred = ICmpInst::ICMP_SLT;
NewRHS = Constant::getNullValue(X->getType());
break;
if (ICmpInst::isSigned(Pred))
Pred = ICmpInst::getSwappedPredicate(Pred);
else if (ICmpInst::isUnsigned(Pred))
Pred = ICmpInst::getSignedPredicate(Pred);
// else for equality-comparisons just keep the predicate.
case ICmpInst::ICMP_SGE:
NewPred = ICmpInst::ICMP_SLE;
NewRHS = Constant::getNullValue(X->getType());
break;
case ICmpInst::ICMP_SLT:
NewPred = ICmpInst::ICMP_SGT;
NewRHS = Constant::getNullValue(X->getType());
break;
case ICmpInst::ICMP_SLE:
NewPred = ICmpInst::ICMP_SGE;
NewRHS = Constant::getNullValue(X->getType());
break;
case ICmpInst::ICMP_UGT:
NewPred = ICmpInst::ICMP_SGT;
NewRHS = Constant::getNullValue(X->getType());
break;
case ICmpInst::ICMP_UGE:
NewPred = ICmpInst::ICMP_SGE;
NewRHS = Constant::getNullValue(X->getType());
break;
case ICmpInst::ICMP_ULT:
NewPred = ICmpInst::ICMP_SLT;
NewRHS = Constant::getNullValue(X->getType());
break;
case ICmpInst::ICMP_ULE:
NewPred = ICmpInst::ICMP_SLE;
NewRHS = Constant::getNullValue(X->getType());
break;
case ICmpInst::ICMP_EQ:
case ICmpInst::ICMP_NE:
NewPred = Pred;
NewRHS = Constant::getNullValue(X->getType());
break;
default:
return nullptr;
}
return ICmpInst::Create(Instruction::ICmp, NewPred, X, NewRHS, I.getName());
return ICmpInst::Create(Instruction::ICmp, Pred, X,
Constant::getNullValue(X->getType()), I.getName());
}
/// Try to fold icmp (binop), X or icmp X, (binop).