diff options
Diffstat (limited to 'llvm/lib/Transforms/Scalar/InstructionCombining.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Scalar/InstructionCombining.cpp | 27 |
1 files changed, 26 insertions, 1 deletions
diff --git a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp index 0c790f63150..b608186338e 100644 --- a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp @@ -101,6 +101,20 @@ namespace { Add(I); } + /// AddInitialGroup - Add the specified batch of stuff in reverse order. + /// which should only be done when the worklist is empty and when the group + /// has no duplicates. + void AddInitialGroup(Instruction *const *List, unsigned NumEntries) { + assert(Worklist.empty() && "Worklist must be empty to add initial group"); + Worklist.reserve(NumEntries+16); + DEBUG(errs() << "IC: ADDING: " << NumEntries << " instrs to worklist\n"); + for (; NumEntries; --NumEntries) { + Instruction *I = List[NumEntries-1]; + WorklistMap.insert(std::make_pair(I, Worklist.size())); + Worklist.push_back(I); + } + } + // Remove - remove I from the worklist if it exists. void Remove(Instruction *I) { DenseMap<Instruction*, unsigned>::iterator It = WorklistMap.find(I); @@ -12663,6 +12677,9 @@ static void AddReachableCodeToWorklist(BasicBlock *BB, const TargetData *TD) { SmallVector<BasicBlock*, 256> Worklist; Worklist.push_back(BB); + + std::vector<Instruction*> InstrsForInstCombineWorklist; + InstrsForInstCombineWorklist.reserve(128); while (!Worklist.empty()) { BB = Worklist.back(); @@ -12709,7 +12726,7 @@ static void AddReachableCodeToWorklist(BasicBlock *BB, DBI_Prev = 0; } - IC.Worklist.Add(Inst); + InstrsForInstCombineWorklist.push_back(Inst); } // Recursively visit successors. If this is a branch or switch on a @@ -12741,6 +12758,14 @@ static void AddReachableCodeToWorklist(BasicBlock *BB, for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) Worklist.push_back(TI->getSuccessor(i)); } + + // Once we've found all of the instructions to add to instcombine's worklist, + // add them in reverse order. This way instcombine will visit from the top + // of the function down. This jives well with the way that it adds all uses + // of instructions to the worklist after doing a transformation, thus avoiding + // some N^2 behavior in pathological cases. + IC.Worklist.AddInitialGroup(&InstrsForInstCombineWorklist[0], + InstrsForInstCombineWorklist.size()); } bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) { |
