Add test exposing a bug in SimpleLoopUnswitch.

diff --git a/llvm/test/Transforms/SimpleLoopUnswitch/dead-blocks-uses-in-unreachablel-blocks.ll b/llvm/test/Transforms/SimpleLoopUnswitch/dead-blocks-uses-in-unreachablel-blocks.ll
new file mode 100644 (file)
index 0000000..4dec9a3
--- /dev/null
+++ b/llvm/test/Transforms/SimpleLoopUnswitch/dead-blocks-uses-in-unreachablel-blocks.ll
@@ -0,0 +1,33 @@
+; XFAIL: *
+; REQUIRES: asserts
+; RUN: opt < %s -passes='unswitch<nontrivial>' -disable-output
+; RUN: opt < %s -simple-loop-unswitch -enable-nontrivial-unswitch -disable-output
+
+
+; Make sure we don't crash due to a dangling use of %tmp2 in bb7.
+define void @test.use_in_dead_block(i1 %arg1, i1 %arg2) {
+bb1:
+  br label %bb2
+
+bb2:                                              ; preds = %bb4, %bb1
+  %tmp1 = phi i64 [ 0, %bb4 ], [ 42, %bb1 ]
+  br i1 %arg1, label %bb3, label %bb6
+
+bb3:                                              ; preds = %bb2
+  br i1 %arg2, label %bb5, label %bb4
+
+bb4:                                              ; preds = %bb3
+  %tmp2 = add i32 1, 1
+  br label %bb2
+
+bb5:                                             ; preds = %bb3
+  ret void
+
+bb6:                                             ; preds = %bb2
+  %tmp3 = add i64 %tmp1, 1
+  ret void
+
+bb7:                                             ; No predecessors!
+  %tmp4 = add i32 %tmp2, 1
+  ret void
+}