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| author | Duncan P. N. Exon Smith <dexonsmith@apple.com> | 2013-12-06 21:48:36 +0000 |
|---|---|---|
| committer | Duncan P. N. Exon Smith <dexonsmith@apple.com> | 2013-12-06 21:48:36 +0000 |
| commit | ce5f93efd55285bf4ab1adcd9511973213e03982 (patch) | |
| tree | 27ef2044480087ce965429ab65daa93cbf40ea97 | |
| parent | 3dedae12b5453757055857e83a1f2624bf08d914 (diff) | |
| download | bcm5719-llvm-ce5f93efd55285bf4ab1adcd9511973213e03982.tar.gz bcm5719-llvm-ce5f93efd55285bf4ab1adcd9511973213e03982.zip | |
Don't use isNullValue to evaluate ConstantExpr
ConstantExpr can evaluate to false even when isNullValue gives false.
Fixes PR18143.
llvm-svn: 196611
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstructionCombining.cpp | 5 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/phi-select-constexpr.ll | 19 |
2 files changed, 23 insertions, 1 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp index 27f1a3eb699..191a101e0a3 100644 --- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp +++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp @@ -699,7 +699,10 @@ Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) { Value *TrueVInPred = TrueV->DoPHITranslation(PhiTransBB, ThisBB); Value *FalseVInPred = FalseV->DoPHITranslation(PhiTransBB, ThisBB); Value *InV = 0; - if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) + // Beware of ConstantExpr: it may eventually evaluate to getNullValue, + // even if currently isNullValue gives false. + Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i)); + if (InC && !isa<ConstantExpr>(InC)) InV = InC->isNullValue() ? FalseVInPred : TrueVInPred; else InV = Builder->CreateSelect(PN->getIncomingValue(i), diff --git a/llvm/test/Transforms/InstCombine/phi-select-constexpr.ll b/llvm/test/Transforms/InstCombine/phi-select-constexpr.ll new file mode 100644 index 00000000000..054e0691d47 --- /dev/null +++ b/llvm/test/Transforms/InstCombine/phi-select-constexpr.ll @@ -0,0 +1,19 @@ +; RUN: opt < %s -S -instcombine | FileCheck %s +@A = extern_weak global i32, align 4 +@B = extern_weak global i32, align 4 + +define i32 @foo(i1 %which) { +entry: + br i1 %which, label %final, label %delay + +delay: + br label %final + +; CHECK-LABEL: final: +; CHECK: phi i32 [ 1, %entry ], [ select (i1 icmp eq (i32* @A, i32* @B), i32 2, i32 1), %delay ] +final: + %use2 = phi i1 [ false, %entry ], [ icmp eq (i32* @A, i32* @B), %delay ] + %value = select i1 %use2, i32 2, i32 1 + ret i32 %value +} + |
