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Revert 75571; I'm convinced this isn't the right thing to do.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75642 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -109,8 +109,6 @@ static bool MarkAliveBlocks(BasicBlock *BB,
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if (!Reachable.insert(BB))
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continue;
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bool AsmFound = false;
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StoreInst *UndefStore = 0;
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// Do a quick scan of the basic block, turning any obviously unreachable
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// instructions into LLVM unreachable insts. The instruction combining pass
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// canonicalizes unreachable insts into stores to null or undef.
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@ -127,27 +125,20 @@ static bool MarkAliveBlocks(BasicBlock *BB,
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}
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break;
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}
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if (isa<InlineAsm>(CI->getOperand(0)))
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AsmFound = true;
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}
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if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) {
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Value *Ptr = SI->getOperand(1);
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if ((isa<UndefValue>(Ptr) ||
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(isa<ConstantPointerNull>(Ptr) &&
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cast<PointerType>(Ptr->getType())->getAddressSpace() == 0)) &&
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!UndefStore)
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UndefStore = SI;
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if (isa<UndefValue>(Ptr) ||
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(isa<ConstantPointerNull>(Ptr) &&
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cast<PointerType>(Ptr->getType())->getAddressSpace() == 0)) {
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ChangeToUnreachable(SI, Context);
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Changed = true;
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break;
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}
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}
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}
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// We can't delete asm's just because their inputs are undefined;
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// xor R, R is a common idiom for zeroing a register, for example.
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// Assume user knows what he is doing.
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if (UndefStore && !AsmFound) {
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ChangeToUnreachable(UndefStore, Context);
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Changed = true;
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}
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// Turn invokes that call 'nounwind' functions into ordinary calls.
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if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator()))
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@ -1,11 +0,0 @@
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; RUN: llvm-as < %s | opt -simplifycfg | llvm-dis | grep xor
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; ModuleID = '<stdin>'
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target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
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target triple = "i386-apple-darwin9.6"
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define void @bar() nounwind {
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entry:
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store i16 undef, i16* null
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%asmtmp = call i32 asm sideeffect "xor $0, $0", "=={bx},rm,~{dirflag},~{fpsr},~{flags},~{memory}"(i16 undef) nounwind ; <i32> [#uses=0]
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ret void
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}
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