diff options
| -rw-r--r-- | lib/Transforms/InstCombine/InstructionCombining.cpp | 5 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/phi-select-constexpr.ll | 19 |
2 files changed, 23 insertions, 1 deletions
diff --git a/lib/Transforms/InstCombine/InstructionCombining.cpp b/lib/Transforms/InstCombine/InstructionCombining.cpp index 27f1a3e..191a101 100644 --- a/lib/Transforms/InstCombine/InstructionCombining.cpp +++ b/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/test/Transforms/InstCombine/phi-select-constexpr.ll b/test/Transforms/InstCombine/phi-select-constexpr.ll new file mode 100644 index 0000000..054e069 --- /dev/null +++ b/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 +} + |