diff options
| -rw-r--r-- | lib/Transforms/Utils/Local.cpp | 21 |
1 files changed, 20 insertions, 1 deletions
diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp index 4d141533b8..0ed669643e 100644 --- a/lib/Transforms/Utils/Local.cpp +++ b/lib/Transforms/Utils/Local.cpp @@ -373,7 +373,26 @@ Constant *llvm::ConstantFoldCall(Function *F, // bool llvm::isInstructionTriviallyDead(Instruction *I) { - return I->use_empty() && !I->mayWriteToMemory() && !isa<TerminatorInst>(I); + if (!I->use_empty() || isa<TerminatorInst>(I)) return false; + + if (!I->mayWriteToMemory()) return true; + + if (CallInst *CI = dyn_cast<CallInst>(I)) + if (Function *F = CI->getCalledFunction()) + switch (F->getIntrinsicID()) { + default: break; + case Intrinsic::vastart: + case Intrinsic::vacopy: + case Intrinsic::returnaddress: + case Intrinsic::frameaddress: + case Intrinsic::isunordered: + case Intrinsic::ctpop: + case Intrinsic::ctlz: + case Intrinsic::cttz: + case Intrinsic::sqrt: + return true; // These intrinsics have no side effects. + } + return false; } // dceInstruction - Inspect the instruction at *BBI and figure out if it's |