From c9e4816fe319b2fde83779ff375037c8079d36a2 Mon Sep 17 00:00:00 2001
From: Dylan MacKenzie <ecstaticmorse@gmail.com>
Date: Wed, 18 Sep 2019 14:53:55 -0700
Subject: [PATCH] Add convenience function for detecting cyclic CFGs

---
 src/librustc/mir/mod.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/librustc/mir/mod.rs b/src/librustc/mir/mod.rs
index 0ebc70750a6..5206e044f9f 100644
--- a/src/librustc/mir/mod.rs
+++ b/src/librustc/mir/mod.rs
@@ -262,6 +262,12 @@ impl<'tcx> Body<'tcx> {
         dominators(self)
     }
 
+    /// Returns `true` if a cycle exists in the control-flow graph that is reachable from the
+    /// `START_BLOCK`.
+    pub fn is_cfg_cyclic(&self) -> bool {
+        graph::is_cyclic(self)
+    }
+
     #[inline]
     pub fn local_kind(&self, local: Local) -> LocalKind {
         let index = local.as_usize();