diff options
| -rw-r--r-- | lib/Transforms/Scalar/TailDuplication.cpp | 20 |
1 files changed, 15 insertions, 5 deletions
diff --git a/lib/Transforms/Scalar/TailDuplication.cpp b/lib/Transforms/Scalar/TailDuplication.cpp index 8cb28a3b06..3fd09f107c 100644 --- a/lib/Transforms/Scalar/TailDuplication.cpp +++ b/lib/Transforms/Scalar/TailDuplication.cpp @@ -39,8 +39,9 @@ using namespace llvm; STATISTIC(NumEliminated, "Number of unconditional branches eliminated"); static cl::opt<unsigned> -Threshold("taildup-threshold", cl::desc("Max block size to tail duplicate"), - cl::init(6), cl::Hidden); +TailDupThreshold("taildup-threshold", + cl::desc("Max block size to tail duplicate"), + cl::init(1), cl::Hidden); namespace { class VISIBILITY_HIDDEN TailDup : public FunctionPass { @@ -50,7 +51,7 @@ namespace { TailDup() : FunctionPass((intptr_t)&ID) {} private: - inline bool shouldEliminateUnconditionalBranch(TerminatorInst *TI); + inline bool shouldEliminateUnconditionalBranch(TerminatorInst *, unsigned); inline void eliminateUnconditionalBranch(BranchInst *BI); SmallPtrSet<BasicBlock*, 4> CycleDetector; }; @@ -70,7 +71,8 @@ bool TailDup::runOnFunction(Function &F) { bool Changed = false; CycleDetector.clear(); for (Function::iterator I = F.begin(), E = F.end(); I != E; ) { - if (shouldEliminateUnconditionalBranch(I->getTerminator())) { + if (shouldEliminateUnconditionalBranch(I->getTerminator(), + TailDupThreshold)) { eliminateUnconditionalBranch(cast<BranchInst>(I->getTerminator())); Changed = true; } else { @@ -90,7 +92,8 @@ bool TailDup::runOnFunction(Function &F) { /// We don't count PHI nodes in the count since they will be removed when the /// contents of the block are copied over. /// -bool TailDup::shouldEliminateUnconditionalBranch(TerminatorInst *TI) { +bool TailDup::shouldEliminateUnconditionalBranch(TerminatorInst *TI, + unsigned Threshold) { BranchInst *BI = dyn_cast<BranchInst>(TI); if (!BI || !BI->isUnconditional()) return false; // Not an uncond branch! @@ -124,6 +127,13 @@ bool TailDup::shouldEliminateUnconditionalBranch(TerminatorInst *TI) { // Don't tail duplicate call instructions. They are very large compared to // other instructions. if (isa<CallInst>(I) || isa<InvokeInst>(I)) return false; + + // Allso alloca and malloc. + if (isa<AllocationInst>(I)) return false; + + // Some vector instructions can expand into a number of instructions. + if (isa<ShuffleVectorInst>(I) || isa<ExtractElementInst>(I) || + isa<InsertElementInst>(I)) return false; // Only count instructions that are not debugger intrinsics. if (!isa<DbgInfoIntrinsic>(I)) ++Size; |