diff options
Diffstat (limited to 'llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp index 071985eb641..fd5a4682aa2 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -5386,6 +5386,36 @@ static Instruction *foldVectorCmp(CmpInst &Cmp, return nullptr; } +// extract(uadd.with.overflow(A, B), 0) ult A +// -> extract(uadd.with.overflow(A, B), 1) +static Instruction *foldICmpOfUAddOv(ICmpInst &I) { + CmpInst::Predicate Pred = I.getPredicate(); + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); + + Value *UAddOv; + Value *A, *B; + auto UAddOvResultPat = m_ExtractValue<0>( + m_Intrinsic<Intrinsic::uadd_with_overflow>(m_Value(A), m_Value(B))); + if (match(Op0, UAddOvResultPat) && + ((Pred == ICmpInst::ICMP_ULT && (Op1 == A || Op1 == B)) || + (Pred == ICmpInst::ICMP_EQ && match(Op1, m_ZeroInt()) && + (match(A, m_One()) || match(B, m_One()))) || + (Pred == ICmpInst::ICMP_NE && match(Op1, m_AllOnes()) && + (match(A, m_AllOnes()) || match(B, m_AllOnes()))))) + // extract(uadd.with.overflow(A, B), 0) < A + // extract(uadd.with.overflow(A, 1), 0) == 0 + // extract(uadd.with.overflow(A, -1), 0) != -1 + UAddOv = cast<ExtractValueInst>(Op0)->getAggregateOperand(); + else if (match(Op1, UAddOvResultPat) && + Pred == ICmpInst::ICMP_UGT && (Op0 == A || Op0 == B)) + // A > extract(uadd.with.overflow(A, B), 0) + UAddOv = cast<ExtractValueInst>(Op1)->getAggregateOperand(); + else + return nullptr; + + return ExtractValueInst::Create(UAddOv, 1); +} + Instruction *InstCombiner::visitICmpInst(ICmpInst &I) { bool Changed = false; const SimplifyQuery Q = SQ.getWithInstruction(&I); @@ -5574,6 +5604,9 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) { if (Instruction *Res = foldICmpEquality(I)) return Res; + if (Instruction *Res = foldICmpOfUAddOv(I)) + return Res; + // The 'cmpxchg' instruction returns an aggregate containing the old value and // an i1 which indicates whether or not we successfully did the swap. // |
