Fix PR2355: bug in ChangeCompareStride. When the loop termination compare is the...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54415 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index 83bdb2cd176b7b942c8611d75388e80070129c51..3d82fd279c5432b085ab9fe9e10e06556261cf2b 100644 (file)
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -1624,10 +1624,10 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
         continue;
       }
 
-      // If scale is negative, use inverse predicate unless it's testing
+      // If scale is negative, use swapped predicate unless it's testing
       // for equality.
       if (Scale < 0 && !Cond->isEquality())
-        Predicate = ICmpInst::getInversePredicate(Predicate);
+        Predicate = ICmpInst::getSwappedPredicate(Predicate);
 
       NewStride = &StrideOrder[i];
       break;

diff --git a/test/Transforms/LoopStrengthReduce/2008-08-06-CmpStride.ll b/test/Transforms/LoopStrengthReduce/2008-08-06-CmpStride.ll
new file mode 100644 (file)
index 0000000..3700c69
--- /dev/null
+++ b/test/Transforms/LoopStrengthReduce/2008-08-06-CmpStride.ll
@@ -0,0 +1,24 @@
+; RUN: llvm-as < %s | opt -loop-reduce | llvm-dis | grep ugt
+; PR2355
+
+@.str = internal constant [4 x i8] c"%d\0A\00"
+
+declare i32 @printf(i8* noalias , ...) nounwind
+
+define i32 @main() nounwind {
+entry:
+        br label %forbody
+
+forbody:
+        %i.0 = phi i32 [ 0, %entry ], [ %inc, %forbody ]                ; <i32>[#uses=3]
+        %sub14 = sub i32 1027, %i.0             ; <i32> [#uses=1]
+        %mul15 = mul i32 %sub14, 10             ; <i32> [#uses=1]
+        %add166 = or i32 %mul15, 1              ; <i32> [#uses=1] *
+        call i32 (i8*, ...)* @printf( i8* noalias  getelementptr ([4 x i8]* @.str, i32 0, i32 0), i32 %add166 ) nounwind
+        %inc = add i32 %i.0, 1          ; <i32> [#uses=3]
+        %cmp = icmp ult i32 %inc, 1027          ; <i1> [#uses=1]
+        br i1 %cmp, label %forbody, label %afterfor
+
+afterfor:               ; preds = %forcond
+        ret i32 0
+}