[NFC] Add motivating test case for revert in rL346198

llvm-svn: 346199

1 files changed, 35 insertions, 0 deletions

diff --git a/llvm/test/Transforms/IndVarSimplify/constant_result.ll b/llvm/test/Transforms/IndVarSimplify/constant_result.ll
new file mode 100644
index 00000000000..749c4af07ae
--- /dev/null
+++ b/llvm/test/Transforms/IndVarSimplify/constant_result.ll
@@ -0,0 +1,35 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -indvars -S | FileCheck %s
+
+@Y = global [400 x i16] zeroinitializer, align 1
+
+define i16 @foo() {
+; CHECK-LABEL: @foo(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[I:%.*]] = phi i16 [ 0, [[ENTRY:%.*]] ], [ [[INC:%.*]], [[FOR_BODY]] ]
+; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds [400 x i16], [400 x i16]* @Y, i16 0, i16 [[I]]
+; CHECK-NEXT:    store i16 0, i16* [[ARRAYIDX]], align 1
+; CHECK-NEXT:    [[INC]] = add nuw nsw i16 [[I]], 1
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i16 [[INC]], 400
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret i16 400
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %i = phi i16 [ 0, %entry ], [ %inc, %for.body ]
+
+  %arrayidx = getelementptr inbounds [400 x i16], [400 x i16]* @Y, i16 0, i16 %i
+  store i16 0, i16* %arrayidx, align 1
+  %inc = add nuw nsw i16 %i, 1
+  %cmp = icmp ult i16 %inc, 400
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body
+  %inc.lcssa = phi i16 [ %inc, %for.body ]
+  ret i16 %inc.lcssa
+}