[Mem2Reg] Avoid replacing load with itself in promoteSingleBlockAlloca.
We do the same thing in rewriteSingleStoreAlloca. Fixes PR37632. Reviewers: chandlerc, davide, efriedma Reviewed By: davide Differential Revision: https://reviews.llvm.org/D47825 llvm-svn: 334187
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@ -511,6 +511,11 @@ static bool promoteSingleBlockAlloca(AllocaInst *AI, const AllocaInfo &Info,
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!isKnownNonZero(ReplVal, DL, 0, AC, LI, &DT))
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!isKnownNonZero(ReplVal, DL, 0, AC, LI, &DT))
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addAssumeNonNull(AC, LI);
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addAssumeNonNull(AC, LI);
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// If the replacement value is the load, this must occur in unreachable
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// code.
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if (ReplVal == LI)
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ReplVal = UndefValue::get(LI->getType());
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LI->replaceAllUsesWith(ReplVal);
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LI->replaceAllUsesWith(ReplVal);
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}
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}
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@ -0,0 +1,20 @@
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; RUN: opt -mem2reg < %s -S | FileCheck %s
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; CHECK-LABEL: void @patatino()
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; CHECK-NEXT: ret void
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; CHECK-LABEL: cantreachme:
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; CHECK-NEXT: %dec = add nsw i32 undef, -1
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; CHECK-NEXT: br label %cantreachme
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define void @patatino() {
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%a = alloca i32, align 4
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ret void
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cantreachme:
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%dec = add nsw i32 %tmp, -1
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store i32 %dec, i32* %a
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store i32 %tmp, i32* %a
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%tmp = load i32, i32* %a
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br label %cantreachme
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}
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