Fix SplitBlockPredecessors' LoopInfo updating code to handle the case

where a loop's header is being split and it has predecessors which are not
contained by the most-nested loop which contains the loop.
This fixes PR5235.

llvm-svn: 84505

1 files changed, 20 insertions, 0 deletions

diff --git a/llvm/test/Transforms/LoopSimplify/unreachable-loop-pred.ll b/llvm/test/Transforms/LoopSimplify/unreachable-loop-pred.ll
new file mode 100644
index 00000000000..faaaf97d72f
--- /dev/null
+++ b/llvm/test/Transforms/LoopSimplify/unreachable-loop-pred.ll
@@ -0,0 +1,20 @@
+; RUN: opt -S -loopsimplify -disable-output -verify-loop-info -verify-dom-info < %s
+; PR5235
+
+; When loopsimplify inserts a preheader for this loop, it should add the new
+; block to the enclosing loop and not get confused by the unreachable
+; bogus loop entry.
+
+define void @is_extract_cab() nounwind {
+entry:
+  br label %header
+
+header:                                       ; preds = %if.end206, %cond.end66, %if.end23
+  br label %while.body115
+
+while.body115:                                    ; preds = %9, %if.end192, %if.end101
+  br i1 undef, label %header, label %while.body115
+
+foo:
+  br label %while.body115
+}