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[InstCombine] Combine code for and/or of icmps (NFC) 

The implementation for and/or is the same, apart from the choice
of exactIntersectWith() vs exactUnionWith(). Extract a common
function to make future extension easier.
This commit is contained in:
Nikita Popov 2021-11-09 21:17:09 +01:00
parent a8b2277069
commit 0aabdad1ef
1 changed files with 34 additions and 44 deletions
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78
llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
View File

@ -1199,6 +1199,34 @@ static Value *foldAndOrOfICmpsWithConstEq(ICmpInst *Cmp0, ICmpInst *Cmp1,
return Builder.CreateBinOp(Logic.getOpcode(), Cmp0, SubstituteCmp);
}
/// Fold (icmp Pred1 V1, C1) & (icmp Pred2 V2, C2)
/// or (icmp Pred1 V1, C1) | (icmp Pred2 V2, C2)
/// into a single comparison using range-based reasoning.
static Value *foldAndOrOfICmpsUsingRanges(
ICmpInst::Predicate Pred1, Value *V1, const APInt &C1,
ICmpInst::Predicate Pred2, Value *V2, const APInt &C2,
IRBuilderBase &Builder, bool IsAnd) {
if (V1 != V2)
return nullptr;
ConstantRange CR1 = ConstantRange::makeExactICmpRegion(Pred1, C1);
ConstantRange CR2 = ConstantRange::makeExactICmpRegion(Pred2, C2);
Optional<ConstantRange> CR =
IsAnd ? CR1.exactIntersectWith(CR2) : CR1.exactUnionWith(CR2);
if (!CR)
return nullptr;
CmpInst::Predicate NewPred;
APInt NewC, Offset;
CR->getEquivalentICmp(NewPred, NewC, Offset);
Type *Ty = V1->getType();
Value *NewV = V1;
if (Offset != 0)
NewV = Builder.CreateAdd(NewV, ConstantInt::get(Ty, Offset));
return Builder.CreateICmp(NewPred, NewV, ConstantInt::get(Ty, NewC));
}
/// Fold (icmp)&(icmp) if possible.
Value *InstCombinerImpl::foldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS,
BinaryOperator &And) {
@ -1317,28 +1345,9 @@ Value *InstCombinerImpl::foldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS,
}
}
// From here on, we only handle:
// (icmp1 A, C1) & (icmp2 A, C2) --> something simpler.
if (LHS0 != RHS0)
return nullptr;
ConstantRange CR1 =
ConstantRange::makeExactICmpRegion(PredL, LHSC->getValue());
ConstantRange CR2 =
ConstantRange::makeExactICmpRegion(PredR, RHSC->getValue());
Optional<ConstantRange> CR = CR1.exactIntersectWith(CR2);
if (!CR)
return nullptr;
CmpInst::Predicate Pred;
APInt NewRHS, Offset;
CR->getEquivalentICmp(Pred, NewRHS, Offset);
Type *Ty = LHS0->getType();
Value *NewLHS = LHS0;
if (Offset != 0)
NewLHS = Builder.CreateAdd(NewLHS, ConstantInt::get(Ty, Offset));
return Builder.CreateICmp(Pred, NewLHS, ConstantInt::get(Ty, NewRHS));
return foldAndOrOfICmpsUsingRanges(PredL, LHS0, LHSC->getValue(),
PredR, RHS0, RHSC->getValue(),
Builder, /* IsAnd */ true);
}
Value *InstCombinerImpl::foldLogicOfFCmps(FCmpInst *LHS, FCmpInst *RHS,
@ -2462,28 +2471,9 @@ Value *InstCombinerImpl::foldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS,
return Builder.CreateICmpULE(LHS0, LHSC);
}
// From here on, we only handle:
// (icmp1 A, C1) | (icmp2 A, C2) --> something simpler.
if (LHS0 != RHS0)
return nullptr;
ConstantRange CR1 =
ConstantRange::makeExactICmpRegion(PredL, LHSC->getValue());
ConstantRange CR2 =
ConstantRange::makeExactICmpRegion(PredR, RHSC->getValue());
Optional<ConstantRange> CR = CR1.exactUnionWith(CR2);
if (!CR)
return nullptr;
CmpInst::Predicate Pred;
APInt NewRHS, Offset;
CR->getEquivalentICmp(Pred, NewRHS, Offset);
Type *Ty = LHS0->getType();
Value *NewLHS = LHS0;
if (Offset != 0)
NewLHS = Builder.CreateAdd(NewLHS, ConstantInt::get(Ty, Offset));
return Builder.CreateICmp(Pred, NewLHS, ConstantInt::get(Ty, NewRHS));
return foldAndOrOfICmpsUsingRanges(PredL, LHS0, LHSC->getValue(),
PredR, RHS0, RHSC->getValue(),
Builder, /* IsAnd */ false);
}
// FIXME: We use commutative matchers (m_c_*) for some, but not all, matches