Add a chromium version abort function for tcmalloc: Abort().

third_party/tcmalloc/chromium/src/base/abort.h

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// ---
+// On some platforms abort() is implemented in a way that Chrome's crash
+// reporter treats it as a normal exit. See issue:
+// http://code.google.com/p/chromium/issues/detail?id=118665
+// So we replace abort with a
+// segmentation fault, that crash reporter can always detect.
+
+#ifndef BASE_ABORT_H_
+#define BASE_ABORT_H_
+
+#if defined(TCMALLOC_USE_SYSTEM_ABORT)
+#include <stdlib.h>
+
+namespace tcmalloc {
+inline void Abort() {
+  abort();
+}
+} // namespace tcmalloc
+
+#else
+namespace tcmalloc {
+inline void Abort() {
+  // Make a segmentation fault to force abort.
+  *reinterpret_cast<int*>(NULL) = 0x2001;

[hans, 2012/05/15 11:38:07]

This causes a Clang warning:

abort.h:28:3: warning: indirection of non-volatile null pointer will be deleted,
not trap [-Wnull-dereference]
  *reinterpret_cast<int*>(NULL) = 0x2001;
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~


The write to null will be optimized away (since it's undefined behavior, the
compiler is free to do that), and hence the Abort() function will do nothing.

This is easy to fix by making the pointer volatile:

  *reinterpret_cast<volatile int*>(NULL) = 0x2001;

Would it be possible to fix this?

[kaiwang, 2012/05/15 17:56:03]

Sure, I'll fix. Sorry for the inconvenience

[kaiwang, 2012/05/15 18:04:51]

Just curious, I don't see this warning while compiling. So it's by default
turned off? Then is the optimizing by default on?

+}
+} // namespace tcmalloc
+
+#endif
+
+#endif  // BASE_ABORT_H_