diff options
| -rw-r--r-- | lib/Transforms/Scalar/LoopStrengthReduce.cpp | 4 | ||||
| -rw-r--r-- | test/CodeGen/X86/negative-stride-fptosi-user.ll | 25 |
2 files changed, 29 insertions, 0 deletions
diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp index 4c305aae83..e20fb16fb1 100644 --- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp +++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp @@ -2262,6 +2262,10 @@ void LoopStrengthReduce::OptimizeShadowIV(Loop *L) { if (!C) continue; + // Ignore negative constants, as the code below doesn't handle them + // correctly. TODO: Remove this restriction. + if (!C->getValue().isStrictlyPositive()) continue; + /* Add new PHINode. */ PHINode *NewPH = PHINode::Create(DestTy, "IV.S.", PH); diff --git a/test/CodeGen/X86/negative-stride-fptosi-user.ll b/test/CodeGen/X86/negative-stride-fptosi-user.ll new file mode 100644 index 0000000000..332e0b9cc6 --- /dev/null +++ b/test/CodeGen/X86/negative-stride-fptosi-user.ll @@ -0,0 +1,25 @@ +; RUN: llc < %s -march=x86-64 | grep cvtsi2sd + +; LSR previously eliminated the sitofp by introducing an induction +; variable which stepped by a bogus ((double)UINT32_C(-1)). It's theoretically +; possible to eliminate the sitofp using a proper -1.0 step though; this +; test should be changed if that is done. + +define void @foo(i32 %N) nounwind { +entry: + %0 = icmp slt i32 %N, 0 ; <i1> [#uses=1] + br i1 %0, label %bb, label %return + +bb: ; preds = %bb, %entry + %i.03 = phi i32 [ 0, %entry ], [ %2, %bb ] ; <i32> [#uses=2] + %1 = sitofp i32 %i.03 to double ; <double> [#uses=1] + tail call void @bar(double %1) nounwind + %2 = add nsw i32 %i.03, -1 ; <i32> [#uses=2] + %exitcond = icmp eq i32 %2, %N ; <i1> [#uses=1] + br i1 %exitcond, label %return, label %bb + +return: ; preds = %bb, %entry + ret void +} + +declare void @bar(double) |