diff options
| -rw-r--r-- | lib/Transforms/Scalar/GVN.cpp | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp index 927a3ac8a2..ec4d7cb579 100644 --- a/lib/Transforms/Scalar/GVN.cpp +++ b/lib/Transforms/Scalar/GVN.cpp @@ -1311,7 +1311,15 @@ struct AvailableValueInBlock { static Value *ConstructSSAForLoadSet(LoadInst *LI, SmallVectorImpl<AvailableValueInBlock> &ValuesPerBlock, const TargetData *TD, + const DominatorTree &DT, AliasAnalysis *AA) { + // Check for the fully redundant, dominating load case. In this case, we can + // just use the dominating value directly. + if (ValuesPerBlock.size() == 1 && + DT.properlyDominates(ValuesPerBlock[0].BB, LI->getParent())) + return ValuesPerBlock[0].MaterializeAdjustedValue(LI->getType(), TD); + + // Otherwise, we have to construct SSA form. SmallVector<PHINode*, 8> NewPHIs; SSAUpdater SSAUpdate(&NewPHIs); SSAUpdate.Initialize(LI); @@ -1494,7 +1502,7 @@ bool GVN::processNonLocalLoad(LoadInst *LI, DEBUG(errs() << "GVN REMOVING NONLOCAL LOAD: " << *LI << '\n'); // Perform PHI construction. - Value *V = ConstructSSAForLoadSet(LI, ValuesPerBlock, TD, + Value *V = ConstructSSAForLoadSet(LI, ValuesPerBlock, TD, *DT, VN.getAliasAnalysis()); LI->replaceAllUsesWith(V); @@ -1683,7 +1691,7 @@ bool GVN::processNonLocalLoad(LoadInst *LI, ValuesPerBlock.push_back(AvailableValueInBlock::get(UnavailablePred,NewLoad)); // Perform PHI construction. - Value *V = ConstructSSAForLoadSet(LI, ValuesPerBlock, TD, + Value *V = ConstructSSAForLoadSet(LI, ValuesPerBlock, TD, *DT, VN.getAliasAnalysis()); LI->replaceAllUsesWith(V); if (isa<PHINode>(V)) |