diff options
| -rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 06a5660..9d88354 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -12681,6 +12681,9 @@ 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(); @@ -12727,7 +12730,7 @@ 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 @@ -12759,6 +12762,16 @@ 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. + for (std::vector<Instruction*>::reverse_iterator + I = InstrsForInstCombineWorklist.rbegin(), + E = InstrsForInstCombineWorklist.rend(); I != E; ++I) + IC.Worklist.Add(*I); } bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) { |