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DCE intrinsic instructions without side effects.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21719 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -373,7 +373,26 @@ Constant *llvm::ConstantFoldCall(Function *F,
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//
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bool llvm::isInstructionTriviallyDead(Instruction *I) {
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return I->use_empty() && !I->mayWriteToMemory() && !isa<TerminatorInst>(I);
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if (!I->use_empty() || isa<TerminatorInst>(I)) return false;
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if (!I->mayWriteToMemory()) return true;
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if (CallInst *CI = dyn_cast<CallInst>(I))
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if (Function *F = CI->getCalledFunction())
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switch (F->getIntrinsicID()) {
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default: break;
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case Intrinsic::vastart:
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case Intrinsic::vacopy:
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case Intrinsic::returnaddress:
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case Intrinsic::frameaddress:
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case Intrinsic::isunordered:
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case Intrinsic::ctpop:
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case Intrinsic::ctlz:
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case Intrinsic::cttz:
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case Intrinsic::sqrt:
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return true; // These intrinsics have no side effects.
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}
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return false;
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}
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// dceInstruction - Inspect the instruction at *BBI and figure out if it's
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