diff options
| -rw-r--r-- | lib/Transforms/Scalar/CodeGenPrepare.cpp | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/lib/Transforms/Scalar/CodeGenPrepare.cpp b/lib/Transforms/Scalar/CodeGenPrepare.cpp index 60c7f7565e..1f0930df06 100644 --- a/lib/Transforms/Scalar/CodeGenPrepare.cpp +++ b/lib/Transforms/Scalar/CodeGenPrepare.cpp @@ -22,6 +22,7 @@ #include "llvm/Instructions.h" #include "llvm/IntrinsicInst.h" #include "llvm/Pass.h" +#include "llvm/Analysis/InstructionSimplify.h" #include "llvm/Analysis/ProfileInfo.h" #include "llvm/Target/TargetData.h" #include "llvm/Target/TargetLowering.h" @@ -959,7 +960,15 @@ bool CodeGenPrepare::OptimizeBlock(BasicBlock &BB) { for (BasicBlock::iterator BBI = BB.begin(), E = BB.end(); BBI != E; ) { Instruction *I = BBI++; - if (CastInst *CI = dyn_cast<CastInst>(I)) { + if (PHINode *P = dyn_cast<PHINode>(I)) { + // It is possible for very late stage optimizations (such as SimplifyCFG) + // to introduce PHI nodes too late to be cleaned up. If we detect such a + // trivial PHI, go ahead and zap it here. + if (Value *V = SimplifyInstruction(P)) { + P->replaceAllUsesWith(V); + P->eraseFromParent(); + } + } else if (CastInst *CI = dyn_cast<CastInst>(I)) { // If the source of the cast is a constant, then this should have // already been constant folded. The only reason NOT to constant fold // it is if something (e.g. LSR) was careful to place the constant |