From f6ae904e349b01dfe1808752118e3f2f5b44bbc1 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Tue, 11 Jan 2011 08:13:40 +0000 Subject: Fix FoldSingleEntryPHINodes to update memdep and AA when it deletes phi nodes. It is called from MergeBlockIntoPredecessor which is called from GVN, which claims to preserve these. I'm skeptical that this is the actual problem behind PR8954, but this is a stab in the right direction. llvm-svn: 123222 --- llvm/lib/Transforms/Utils/BasicBlockUtils.cpp | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) (limited to 'llvm/lib/Transforms/Utils/BasicBlockUtils.cpp') diff --git a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp index 3daa45cec36..40d33d15afc 100644 --- a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp +++ b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp @@ -19,8 +19,9 @@ #include "llvm/Constant.h" #include "llvm/Type.h" #include "llvm/Analysis/AliasAnalysis.h" -#include "llvm/Analysis/LoopInfo.h" #include "llvm/Analysis/DominanceFrontier.h" +#include "llvm/Analysis/LoopInfo.h" +#include "llvm/Analysis/MemoryDependenceAnalysis.h" #include "llvm/Target/TargetData.h" #include "llvm/Transforms/Utils/Local.h" #include "llvm/Transforms/Scalar.h" @@ -63,12 +64,27 @@ void llvm::DeleteDeadBlock(BasicBlock *BB) { /// any single-entry PHI nodes in it, fold them away. This handles the case /// when all entries to the PHI nodes in a block are guaranteed equal, such as /// when the block has exactly one predecessor. -void llvm::FoldSingleEntryPHINodes(BasicBlock *BB) { +void llvm::FoldSingleEntryPHINodes(BasicBlock *BB, Pass *P) { + if (!isa(BB->begin())) return; + + AliasAnalysis *AA = 0; + MemoryDependenceAnalysis *MemDep = 0; + if (P) { + AA = P->getAnalysisIfAvailable(); + MemDep = P->getAnalysisIfAvailable(); + } + while (PHINode *PN = dyn_cast(BB->begin())) { if (PN->getIncomingValue(0) != PN) PN->replaceAllUsesWith(PN->getIncomingValue(0)); else PN->replaceAllUsesWith(UndefValue::get(PN->getType())); + + if (MemDep) + MemDep->removeInstruction(PN); // Memdep updates AA itself. + else if (AA && isa(PN->getType())) + AA->deleteValue(PN); + PN->eraseFromParent(); } } @@ -132,7 +148,7 @@ bool llvm::MergeBlockIntoPredecessor(BasicBlock *BB, Pass *P) { // Begin by getting rid of unneeded PHIs. if (isa(BB->front())) - FoldSingleEntryPHINodes(BB); + FoldSingleEntryPHINodes(BB, P); // Delete the unconditional branch from the predecessor... PredBB->getInstList().pop_back(); -- cgit v1.2.3