[PATCH] Fix UB in hash-map.h

[Markus Trippelsdorf]

bootstrap-ubsan shows:
  gcc/hash-map.h:277:19: runtime error: member access within null pointer of 
type 'struct hash_map'

Fix the issue by returning early.
bootstrap-ubsan on X86_64 and ppc64le. Tested on ppc64le.

OK for trunk?

gcc/
        * hash-map.h (gt_cleare_cache): Avoid UB.

diff --git a/gcc/hash-map.h b/gcc/hash-map.h
index 6b8365a9d0a6..e5630338491a 100644
--- a/gcc/hash-map.h
+++ b/gcc/hash-map.h
@@ -274,6 +274,8 @@ template<typename K, typename V, typename H>
 static inline void
 gt_cleare_cache (hash_map<K, V, H> *h)
 {
+  if (!h)
+    return;
   gt_cleare_cache (&h->m_table);
 }
 
-- 
Markus