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[InstCombine] move fold for "(X-Y) == 0"; NFC 

This consolidates related folds that all have a
similar use restriction that may not be necessary.
This commit is contained in:
Sanjay Patel 2021-10-10 11:26:03 -04:00
parent cbd8041b0b
commit 05281d95f2
1 changed files with 7 additions and 8 deletions
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15
llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
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@ -2602,9 +2602,16 @@ Instruction *InstCombinerImpl::foldICmpSubConstant(ICmpInst &Cmp,
// The following transforms are only worth it if the only user of the subtract
// is the icmp.
// TODO: This is an artificial restriction for all of the transforms below
// that only need a single replacement icmp.
if (!Sub->hasOneUse())
return nullptr;
// X - Y == 0 --> X == Y.
// X - Y != 0 --> X != Y.
if (Cmp.isEquality() && C.isZero())
return new ICmpInst(Pred, X, Y);
if (Sub->hasNoSignedWrap()) {
// (icmp sgt (sub nsw X, Y), -1) -> (icmp sge X, Y)
if (Pred == ICmpInst::ICMP_SGT && C.isAllOnes())
@ -3130,14 +3137,6 @@ Instruction *InstCombinerImpl::foldICmpBinOpEqualityWithConstant(
}
}
break;
case Instruction::Sub:
if (BO->hasOneUse()) {
if (C.isZero()) {
// Replace ((sub A, B) != 0) with (A != B).
return new ICmpInst(Pred, BOp0, BOp1);
}
}
break;
case Instruction::Or: {
const APInt *BOC;
if (match(BOp1, m_APInt(BOC)) && BO->hasOneUse() && RHS->isAllOnesValue()) {