js/src/jsapi-tests/hidePointer.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * vim: set ts=8 sts=2 et sw=2 tw=80:
   3  */
   4 /* This Source Code Form is subject to the terms of the Mozilla Public
   5  * License, v. 2.0. If a copy of the MPL was not distributed with this
   6  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   7
   8 #include "mozilla/Atomics.h"
   9
  10 // This is an attempt to hide pointer values from the C++ compiler.  This might
  11 // not stand up in the presence of PGO but that's probably not important.
  12
  13 // g_hidden_pointer is public so that it's limited what the compiler can assume
  14 // about it, and atomic so that we don't run afoul of the compiler's UB
  15 // analysis.
  16
  17 mozilla::Atomic<void*> g_hidden_pointer;
  18
  19 // Call this to install a pointer into the global.
  20
  21 MOZ_NEVER_INLINE void setHiddenPointer(void* p) { g_hidden_pointer = p; }
  22
  23 // Call this to retrieve the pointer.
  24
  25 MOZ_NEVER_INLINE void* getHiddenPointer() { return g_hidden_pointer; }