[PATCH v2] gcc: do not apply store motion on loop with no exits.

[Xin Wang via Gcc]

The temporary variable will not be wrote back to memory as there
is no exit of inifinite loop, so we prohibit applying store motion
on loops with no exits.

Signed-off-by: Xin Wang <yw987194...@gmail.com>

---
 gcc/tree-ssa-loop-im.cc | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/gcc/tree-ssa-loop-im.cc b/gcc/tree-ssa-loop-im.cc
index 225964c6215..de0450f5192 100644
--- a/gcc/tree-ssa-loop-im.cc
+++ b/gcc/tree-ssa-loop-im.cc
@@ -3355,6 +3355,9 @@ loop_suitable_for_sm (class loop *loop ATTRIBUTE_UNUSED,
   unsigned i;
   edge ex;
 
+  if (exits.is_empty())
+    return false;
+
   FOR_EACH_VEC_ELT (exits, i, ex)
     if (ex->flags & (EDGE_ABNORMAL | EDGE_EH))
       return false;
-- 
2.25.1