LoopVectorize: Don't hang forever if a PHI only has skipped PHI uses.

Fixes PR15384.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176366 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 29 insertions, 0 deletions

diff --git a/test/Transforms/LoopVectorize/phi-hang.ll b/test/Transforms/LoopVectorize/phi-hang.ll
new file mode 100644
index 0000000000..b80d45995d
--- /dev/null
+++ b/test/Transforms/LoopVectorize/phi-hang.ll
@@ -0,0 +1,29 @@
+; RUN: opt -S -loop-vectorize < %s
+
+; PR15384
+define void @test1(i32 %arg) {
+bb:
+  br label %bb1
+
+bb1:                                              ; preds = %bb5, %bb
+  %tmp = phi i32 [ 1, %bb ], [ %tmp7, %bb5 ]
+  %tmp2 = phi i32 [ %arg, %bb ], [ %tmp9, %bb5 ]
+  br i1 true, label %bb5, label %bb3
+
+bb3:                                              ; preds = %bb1
+  br label %bb4
+
+bb4:                                              ; preds = %bb3
+  br label %bb5
+
+bb5:                                              ; preds = %bb4, %bb1
+  %tmp6 = phi i32 [ 0, %bb4 ], [ %tmp, %bb1 ]
+  %tmp7 = phi i32 [ 0, %bb4 ], [ %tmp6, %bb1 ]
+  %tmp8 = phi i32 [ 0, %bb4 ], [ %tmp, %bb1 ]
+  %tmp9 = add nsw i32 %tmp2, 1
+  %tmp10 = icmp eq i32 %tmp9, 0
+  br i1 %tmp10, label %bb11, label %bb1
+
+bb11:                                             ; preds = %bb5
+  ret void
+}