diff options
| -rw-r--r-- | lib/Analysis/IPA/GlobalsModRef.cpp | 11 | ||||
| -rw-r--r-- | lib/Analysis/NoAliasAnalysis.cpp | 1 | ||||
| -rw-r--r-- | lib/Transforms/Scalar/GVN.cpp | 21 |
3 files changed, 31 insertions, 2 deletions
diff --git a/lib/Analysis/IPA/GlobalsModRef.cpp b/lib/Analysis/IPA/GlobalsModRef.cpp index c18dc47406..116aaf418e 100644 --- a/lib/Analysis/IPA/GlobalsModRef.cpp +++ b/lib/Analysis/IPA/GlobalsModRef.cpp @@ -152,6 +152,7 @@ namespace { virtual void deleteValue(Value *V); virtual void copyValue(Value *From, Value *To); + virtual void addEscapingUse(Use &U); /// getAdjustedAnalysisPointer - This method is used when a pass implements /// an analysis interface through multiple inheritance. If needed, it @@ -596,3 +597,13 @@ void GlobalsModRef::deleteValue(Value *V) { void GlobalsModRef::copyValue(Value *From, Value *To) { AliasAnalysis::copyValue(From, To); } + +void GlobalsModRef::addEscapingUse(Use &U) { + // For the purposes of this analysis, it is conservatively correct to treat + // a newly escaping value equivalently to a deleted one. We could perhaps + // be more precise by processing the new use and attempting to update our + // saved analysis results to accomodate it. + deleteValue(U); + + AliasAnalysis::addEscapingUse(U); +} diff --git a/lib/Analysis/NoAliasAnalysis.cpp b/lib/Analysis/NoAliasAnalysis.cpp index ab7a69241e..101c2d5b02 100644 --- a/lib/Analysis/NoAliasAnalysis.cpp +++ b/lib/Analysis/NoAliasAnalysis.cpp @@ -65,6 +65,7 @@ namespace { virtual void deleteValue(Value *V) {} virtual void copyValue(Value *From, Value *To) {} + virtual void addEscapingUse(Use &U) {} /// getAdjustedAnalysisPointer - This method is used when a pass implements /// an analysis interface through multiple inheritance. If needed, it diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp index bf46bd98c3..f0e0f38142 100644 --- a/lib/Transforms/Scalar/GVN.cpp +++ b/lib/Transforms/Scalar/GVN.cpp @@ -1063,6 +1063,15 @@ static Value *ConstructSSAForLoadSet(LoadInst *LI, if (V->getType()->isPointerTy()) for (unsigned i = 0, e = NewPHIs.size(); i != e; ++i) AA->copyValue(LI, NewPHIs[i]); + + // Now that we've copied information to the new PHIs, scan through + // them again and inform alias analysis that we've added potentially + // escaping uses to any values that are operands to these PHIs. + for (unsigned i = 0, e = NewPHIs.size(); i != e; ++i) { + PHINode *P = NewPHIs[i]; + for (unsigned ii = 0, ee = P->getNumIncomingValues(); ii != ee; ++ii) + AA->addEscapingUse(P->getOperandUse(2*ii)); + } return V; } @@ -1957,8 +1966,16 @@ bool GVN::performPRE(Function &F) { insert_table(ValNo, Phi, CurrentBlock); CurInst->replaceAllUsesWith(Phi); - if (MD && Phi->getType()->isPointerTy()) - MD->invalidateCachedPointerInfo(Phi); + if (Phi->getType()->isPointerTy()) { + // Because we have added a PHI-use of the pointer value, it has now + // "escaped" from alias analysis' perspective. We need to inform + // AA of this. + for (unsigned ii = 0, ee = Phi->getNumIncomingValues(); ii != ee; ++ii) + VN.getAliasAnalysis()->addEscapingUse(Phi->getOperandUse(2*ii)); + + if (MD) + MD->invalidateCachedPointerInfo(Phi); + } VN.erase(CurInst); erase_table(ValNo, CurInst, CurrentBlock); |