From b5b7997fd0765f73b711ea4c72e4433ce3637794 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Tue, 11 Jan 2011 08:13:40 +0000 Subject: [PATCH] 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. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123222 91177308-0d34-0410-b5e6-96231b3b80d8 --- .../llvm/Transforms/Utils/BasicBlockUtils.h | 4 ++-- lib/Transforms/Scalar/GVN.cpp | 4 ++-- lib/Transforms/Utils/BasicBlockUtils.cpp | 22 ++++++++++++++++--- 3 files changed, 23 insertions(+), 7 deletions(-) diff --git a/include/llvm/Transforms/Utils/BasicBlockUtils.h b/include/llvm/Transforms/Utils/BasicBlockUtils.h index 2e8c335b372..6de8b850704 100644 --- a/include/llvm/Transforms/Utils/BasicBlockUtils.h +++ b/include/llvm/Transforms/Utils/BasicBlockUtils.h @@ -35,7 +35,7 @@ void 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 FoldSingleEntryPHINodes(BasicBlock *BB); +void FoldSingleEntryPHINodes(BasicBlock *BB, Pass *P = 0); /// DeleteDeadPHIs - Examine each PHI in the given block and delete it if it /// is dead. Also recursively delete any operands that become dead as @@ -46,7 +46,7 @@ bool DeleteDeadPHIs(BasicBlock *BB); /// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor, /// if possible. The return value indicates success or failure. -bool MergeBlockIntoPredecessor(BasicBlock* BB, Pass* P = 0); +bool MergeBlockIntoPredecessor(BasicBlock *BB, Pass *P = 0); // ReplaceInstWithValue - Replace all uses of an instruction (specified by BI) // with a value, then remove and delete the original instruction. diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp index b7fc9c30e06..a4bd7c1eb42 100644 --- a/lib/Transforms/Scalar/GVN.cpp +++ b/lib/Transforms/Scalar/GVN.cpp @@ -1741,8 +1741,8 @@ bool GVN::runOnFunction(Function& F) { // Merge unconditional branches, allowing PRE to catch more // optimization opportunities. for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ) { - BasicBlock *BB = FI; - ++FI; + BasicBlock *BB = FI++; + bool removedBlock = MergeBlockIntoPredecessor(BB, this); if (removedBlock) ++NumGVNBlocks; diff --git a/lib/Transforms/Utils/BasicBlockUtils.cpp b/lib/Transforms/Utils/BasicBlockUtils.cpp index 3daa45cec36..40d33d15afc 100644 --- a/lib/Transforms/Utils/BasicBlockUtils.cpp +++ b/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(); -- 2.34.1