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Date: Sun, 26 Nov 2017 10:14:00 -0000
From: Markus Trippelsdorf <markus@trippelsdorf.de>
To: Richard Biener <richard.guenther@gmail.com>
Cc: Jason Merrill <jason@redhat.com>,	gcc-patches List <gcc-patches@gcc.gnu.org>
Subject: [PATCH] Fix UB in hash-map.h
Message-ID: <20171126090520.GA367@x4>
References: <CADzB+2n4mtiYNocfZYCE7xKwEf6aZW+QX9FdR05zf2a-9Qi4TQ@mail.gmail.com> <CAFiYyc3rZDSEp+X7-jtLaq8DbyULJyEnTNdBAPpuZWdYK3c2Kw@mail.gmail.com> <20171125194217.GA367@x4>
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X-SW-Source: 2017-11/txt/msg02248.txt.bz2

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