fix overflow check.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@56011 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index 50dc6d41c1e1eee8d0adcd382d7608e205c759fb..145aa92a60e06a7a4400fa6fd0f26e5e3e713545 100644 (file)
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -1551,8 +1551,7 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
 
   // Check stride constant and the comparision constant signs to detect
   // overflow.
-  if (ICmpInst::isSignedPredicate(Predicate) &&
-      (CmpVal & SignBit) != (CmpSSInt & SignBit))
+  if ((CmpVal & SignBit) != (CmpSSInt & SignBit))
     return Cond;
 
   // Look for a suitable stride / iv as replacement.

diff --git a/test/Transforms/LoopStrengthReduce/2008-09-09-Overflow.ll b/test/Transforms/LoopStrengthReduce/2008-09-09-Overflow.ll
new file mode 100644 (file)
index 0000000..703aebe
--- /dev/null
+++ b/test/Transforms/LoopStrengthReduce/2008-09-09-Overflow.ll
@@ -0,0 +1,48 @@
+; RUN: llvm-as < %s | opt -loop-reduce | llvm-dis | grep phi | count 2
+; PR 2779
+@g_19 = common global i32 0            ; <i32*> [#uses=3]
+@"\01LC" = internal constant [4 x i8] c"%d\0A\00"              ; <[4 x i8]*> [#uses=1]
+
+define i32 @func_8(i8 zeroext %p_9) nounwind {
+entry:
+       ret i32 1
+}
+
+define i32 @func_3(i8 signext %p_5) nounwind {
+entry:
+       ret i32 1
+}
+
+define void @func_1() nounwind {
+entry:
+       br label %bb
+
+bb:            ; preds = %bb, %entry
+       %indvar = phi i16 [ 0, %entry ], [ %indvar.next, %bb ]          ; <i16> [#uses=2]
+       %tmp = sub i16 0, %indvar               ; <i16> [#uses=1]
+       %tmp27 = trunc i16 %tmp to i8           ; <i8> [#uses=1]
+       load i32* @g_19, align 4                ; <i32>:0 [#uses=2]
+       add i32 %0, 1           ; <i32>:1 [#uses=1]
+       store i32 %1, i32* @g_19, align 4
+       trunc i32 %0 to i8              ; <i8>:2 [#uses=1]
+       tail call i32 @func_8( i8 zeroext %2 ) nounwind         ; <i32>:3 [#uses=0]
+       shl i8 %tmp27, 2                ; <i8>:4 [#uses=1]
+       add i8 %4, -112         ; <i8>:5 [#uses=1]
+       tail call i32 @func_3( i8 signext %5 ) nounwind         ; <i32>:6 [#uses=0]
+       %indvar.next = add i16 %indvar, 1               ; <i16> [#uses=2]
+       %exitcond = icmp eq i16 %indvar.next, -28               ; <i1> [#uses=1]
+       br i1 %exitcond, label %return, label %bb
+
+return:                ; preds = %bb
+       ret void
+}
+
+define i32 @main() nounwind {
+entry:
+       tail call void @func_1( ) nounwind
+       load i32* @g_19, align 4                ; <i32>:0 [#uses=1]
+       tail call i32 (i8*, ...)* @printf( i8* getelementptr ([4 x i8]* @"\01LC", i32 0, i32 0), i32 %0 ) nounwind              ; <i32>:1 [#uses=0]
+       ret i32 0
+}
+
+declare i32 @printf(i8*, ...) nounwind