Don't attempt to simplify an non-affine IV expression if it can't

be simplified to a loop-invariant value. This fixes PR4315.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72798 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 43 insertions, 0 deletions

diff --git a/test/Transforms/IndVarSimplify/variable-stride-ivs-0.ll b/test/Transforms/IndVarSimplify/variable-stride-ivs-0.ll
new file mode 100644
index 0000000..759ba8e
--- /dev/null
+++ b/test/Transforms/IndVarSimplify/variable-stride-ivs-0.ll
@@ -0,0 +1,43 @@
+; RUN: llvm-as < %s | opt -indvars -instcombine | llvm-dis | \
+; RUN:   grep {store i32 0}
+; Test that -indvars can reduce variable stride IVs.  If it can reduce variable
+; stride iv's, it will make %iv. and %m.0.0 isomorphic to each other without 
+; cycles, allowing the tmp.21 subtraction to be eliminated.
+; END.
+
+define void @vnum_test8(i32* %data) {
+entry:
+        %tmp.1 = getelementptr i32* %data, i32 3                ; <i32*> [#uses=1]
+        %tmp.2 = load i32* %tmp.1               ; <i32> [#uses=2]
+        %tmp.4 = getelementptr i32* %data, i32 4                ; <i32*> [#uses=1]
+        %tmp.5 = load i32* %tmp.4               ; <i32> [#uses=2]
+        %tmp.8 = getelementptr i32* %data, i32 2                ; <i32*> [#uses=1]
+        %tmp.9 = load i32* %tmp.8               ; <i32> [#uses=3]
+        %tmp.125 = icmp sgt i32 %tmp.2, 0               ; <i1> [#uses=1]
+        br i1 %tmp.125, label %no_exit.preheader, label %return
+
+no_exit.preheader:              ; preds = %entry
+        %tmp.16 = getelementptr i32* %data, i32 %tmp.9          ; <i32*> [#uses=1]
+        br label %no_exit
+
+no_exit:                ; preds = %no_exit, %no_exit.preheader
+        %iv.ui = phi i32 [ 0, %no_exit.preheader ], [ %iv..inc.ui, %no_exit ]           ; <i32> [#uses=1]
+        %iv. = phi i32 [ %tmp.5, %no_exit.preheader ], [ %iv..inc, %no_exit ]           ; <i32> [#uses=2]
+        %m.0.0 = phi i32 [ %tmp.5, %no_exit.preheader ], [ %tmp.24, %no_exit ]          ; <i32> [#uses=2]
+        store i32 2, i32* %tmp.16
+        %tmp.21 = sub i32 %m.0.0, %iv.          ; <i32> [#uses=1]
+        store i32 %tmp.21, i32* %data
+        %tmp.24 = add i32 %m.0.0, %tmp.9                ; <i32> [#uses=1]
+        %iv..inc = add i32 %tmp.9, %iv.         ; <i32> [#uses=1]
+        %iv..inc.ui = add i32 %iv.ui, 1         ; <i32> [#uses=2]
+        %iv..inc1 = bitcast i32 %iv..inc.ui to i32              ; <i32> [#uses=1]
+        %tmp.12 = icmp slt i32 %iv..inc1, %tmp.2                ; <i1> [#uses=1]
+        br i1 %tmp.12, label %no_exit, label %return.loopexit
+
+return.loopexit:                ; preds = %no_exit
+        br label %return
+
+return:         ; preds = %return.loopexit, %entry
+        ret void
+}
+