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[InstSimplify][NFC] Reorganize simplifyUnsignedRangeCheck() to emphasize and/or symmetry 

Only a single `X >= Y && Y == 0  -->  Y == 0` fold appears to be missing.

llvm-svn: 372490
This commit is contained in:
Roman Lebedev 2019-09-21 22:27:28 +00:00
parent ac4dda8052
commit e94f156f77
1 changed files with 11 additions and 8 deletions
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19
llvm/lib/Analysis/InstructionSimplify.cpp
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@ -1443,25 +1443,28 @@ static Value *simplifyUnsignedRangeCheck(ICmpInst *ZeroICmp,
isKnownNonZero(X, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT))
return IsAnd ? UnsignedICmp : ZeroICmp;
// X >= Y && Y == 0 --> Y == 0 FIXME
// X >= Y || Y == 0 --> X >= Y
if (UnsignedPred == ICmpInst::ICMP_UGE && EqPred == ICmpInst::ICMP_EQ &&
!IsAnd)
return UnsignedICmp;
// X > Y && Y == 0 --> Y == 0 iff X != 0
// X > Y || Y == 0 --> X > Y iff X != 0
if (UnsignedPred == ICmpInst::ICMP_UGT && EqPred == ICmpInst::ICMP_EQ &&
isKnownNonZero(X, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT))
return IsAnd ? ZeroICmp : UnsignedICmp;
// X >= Y || Y != 0 --> true
// X >= Y || Y == 0 --> X >= Y
if (UnsignedPred == ICmpInst::ICMP_UGE && !IsAnd) {
if (EqPred == ICmpInst::ICMP_NE)
return getTrue(UnsignedICmp->getType());
return UnsignedICmp;
}
// X < Y && Y == 0 --> false
if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_EQ &&
IsAnd)
return getFalse(UnsignedICmp->getType());
// X >= Y || Y != 0 --> true
if (UnsignedPred == ICmpInst::ICMP_UGE && EqPred == ICmpInst::ICMP_NE &&
!IsAnd)
return getTrue(UnsignedICmp->getType());
return nullptr;
}