[llvm] [NFC][StructurizeCFG] Add a test that can crash StructurizeCFG pass (PR #126087)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Shilei Tian (shiltian)

<details>
<summary>Changes</summary>

I tried to fix it in #<!-- -->124051 but failed to do so. This PR adds the test and
marks it as xfail.

---
Full diff: https://github.com/llvm/llvm-project/pull/126087.diff


1 Files Affected:

- (added) llvm/test/Transforms/StructurizeCFG/simple-structurizecfg-crash.ll (+18) 


``````````diff
diff --git a/llvm/test/Transforms/StructurizeCFG/simple-structurizecfg-crash.ll b/llvm/test/Transforms/StructurizeCFG/simple-structurizecfg-crash.ll
new file mode 100644
index 000000000000000..745b0bdc0382ada
--- /dev/null
+++ b/llvm/test/Transforms/StructurizeCFG/simple-structurizecfg-crash.ll
@@ -0,0 +1,18 @@
+; RUN: opt -S -passes=structurizecfg %s -o -
+; XFAIL: *
+
+; FIXME: This test is expected to crash. Generate checklines after the crash is fixed.
+
+define void @foo() {
+entry:
+  br i1 false, label %cond.true, label %cond.false
+
+cond.true:                                        ; preds = %entry
+  br label %cond.end
+
+cond.false:                                       ; preds = %entry
+  br label %cond.end
+
+cond.end:                                         ; preds = %cond.false, %cond.true
+  ret void
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/126087