diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Analysis/ScalarEvolution.cpp | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp index 10b5c74e378..7a9fddfd10b 100644 --- a/llvm/lib/Analysis/ScalarEvolution.cpp +++ b/llvm/lib/Analysis/ScalarEvolution.cpp @@ -3774,6 +3774,24 @@ void ScalarEvolution::eraseValueFromMap(Value *V) { } } +/// Check whether value has nuw/nsw/exact set but SCEV does not. +/// TODO: In reality it is better to check the poison recursevely +/// but this is better than nothing. +static bool SCEVLostPoisonFlags(const SCEV *S, const Value *V) { + if (auto *I = dyn_cast<Instruction>(V)) { + if (isa<OverflowingBinaryOperator>(I)) { + if (auto *NS = dyn_cast<SCEVNAryExpr>(S)) { + if (I->hasNoSignedWrap() && !NS->hasNoSignedWrap()) + return true; + if (I->hasNoUnsignedWrap() && !NS->hasNoUnsignedWrap()) + return true; + } + } else if (isa<PossiblyExactOperator>(I) && I->isExact()) + return true; + } + return false; +} + /// Return an existing SCEV if it exists, otherwise analyze the expression and /// create a new one. const SCEV *ScalarEvolution::getSCEV(Value *V) { @@ -3787,7 +3805,7 @@ const SCEV *ScalarEvolution::getSCEV(Value *V) { // ValueExprMap before insert S->{V, 0} into ExprValueMap. std::pair<ValueExprMapType::iterator, bool> Pair = ValueExprMap.insert({SCEVCallbackVH(V, this), S}); - if (Pair.second) { + if (Pair.second && !SCEVLostPoisonFlags(S, V)) { ExprValueMap[S].insert({V, nullptr}); // If S == Stripped + Offset, add Stripped -> {V, Offset} into |
