diff options
Diffstat (limited to 'llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp index c265516213aa..16efe863779a 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp @@ -345,10 +345,14 @@ Value *InstCombinerImpl::SimplifyDemandedUseBits(Value *V, APInt DemandedMask, return false; // Get the constant out of the ICmp, if there is one. + // Only try this when exactly 1 operand is a constant (if both operands + // are constant, the icmp should eventually simplify). Otherwise, we may + // invert the transform that reduces set bits and infinite-loop. + Value *X; const APInt *CmpC; ICmpInst::Predicate Pred; - if (!match(I->getOperand(0), m_c_ICmp(Pred, m_APInt(CmpC), m_Value())) || - CmpC->getBitWidth() != SelC->getBitWidth()) + if (!match(I->getOperand(0), m_ICmp(Pred, m_Value(X), m_APInt(CmpC))) || + isa<Constant>(X) || CmpC->getBitWidth() != SelC->getBitWidth()) return ShrinkDemandedConstant(I, OpNo, DemandedMask); // If the constant is already the same as the ICmp, leave it as-is. |