diff options
Diffstat (limited to 'llvm/lib/Transforms/Utils/SimplifyCFG.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Utils/SimplifyCFG.cpp | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp index 33dbbf9..478f32a 100644 --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp @@ -2329,12 +2329,24 @@ static bool FoldTwoEntryPHINode(PHINode *PN, const TargetTransformInfo &TTI, if (!PN) return true; - // Don't fold i1 branches on PHIs which contain binary operators. These can - // often be turned into switches and other things. + // Return true if at least one of these is a 'not', and another is either + // a 'not' too, or a constant. + auto CanHoistNotFromBothValues = [](Value *V0, Value *V1) { + if (!match(V0, m_Not(m_Value()))) + std::swap(V0, V1); + auto Invertible = m_CombineOr(m_Not(m_Value()), m_AnyIntegralConstant()); + return match(V0, m_Not(m_Value())) && match(V1, Invertible); + }; + + // Don't fold i1 branches on PHIs which contain binary operators, unless one + // of the incoming values is an 'not' and another one is freely invertible. + // These can often be turned into switches and other things. if (PN->getType()->isIntegerTy(1) && (isa<BinaryOperator>(PN->getIncomingValue(0)) || isa<BinaryOperator>(PN->getIncomingValue(1)) || - isa<BinaryOperator>(IfCond))) + isa<BinaryOperator>(IfCond)) && + !CanHoistNotFromBothValues(PN->getIncomingValue(0), + PN->getIncomingValue(1))) return false; // If all PHI nodes are promotable, check to make sure that all instructions |