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[NFC] Detect IV increment expressed as uadd_with_overflow and usub_with_overflow 

Current callers do not call it with such argument, so this is NFC.
But for further changes, it can be very useful to detect such cases.
This commit is contained in:
Max Kazantsev 2021-03-01 13:22:42 +07:00
parent 8d835f42a5
commit 9fac8496ea
1 changed files with 6 additions and 0 deletions
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6
llvm/lib/CodeGen/CodeGenPrepare.cpp
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@ -1293,6 +1293,12 @@ getIVIncrement(const PHINode *PN, const LoopInfo *LI) {
return std::make_pair(IVInc, ConstantExpr::getNeg(Step));
if (match(IVInc, m_Add(m_Specific(PN), m_Constant(Step))))
return std::make_pair(IVInc, Step);
if (match(IVInc, m_ExtractValue<0>(m_Intrinsic<Intrinsic::usub_with_overflow>(
m_Specific(PN), m_Constant(Step)))))
return std::make_pair(IVInc, ConstantExpr::getNeg(Step));
if (match(IVInc, m_ExtractValue<0>(m_Intrinsic<Intrinsic::uadd_with_overflow>(
m_Specific(PN), m_Constant(Step)))))
return std::make_pair(IVInc, Step);
return None;
}