tcmalloc: Use C++11 atomics where appropriate.

third_party/tcmalloc/chromium/src/base/atomicops-internals-arm-generic.h

-// Copyright (c) 2003, Google Inc.
-// All rights reserved.
-//
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-// notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-// copyright notice, this list of conditions and the following disclaimer
-// in the documentation and/or other materials provided with the
-// distribution.
-//     * Neither the name of Google Inc. nor the names of its
-// contributors may be used to endorse or promote products derived from
-// this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-// ---
-//
-// Author: Lei Zhang, Sasha Levitskiy
-//
-// This file is an internal atomic implementation, use base/atomicops.h instead.
-//
-// LinuxKernelCmpxchg and Barrier_AtomicIncrement are from Google Gears.
-
-#ifndef BASE_ATOMICOPS_INTERNALS_ARM_GENERIC_H_
-#define BASE_ATOMICOPS_INTERNALS_ARM_GENERIC_H_
-
-#include <stdio.h>
-#include "base/abort.h"
-#include "base/basictypes.h"
-
-typedef int32_t Atomic32;
-
-namespace base {
-namespace subtle {
-
-typedef int64_t Atomic64;
-
-// 0xffff0fc0 is the hard coded address of a function provided by
-// the kernel which implements an atomic compare-exchange. On older
-// ARM architecture revisions (pre-v6) this may be implemented using
-// a syscall. This address is stable, and in active use (hard coded)
-// by at least glibc-2.7 and the Android C library.
-// pLinuxKernelCmpxchg has both acquire and release barrier sematincs.
-typedef Atomic32 (*LinuxKernelCmpxchgFunc)(Atomic32 old_value,
-                                           Atomic32 new_value,
-                                           volatile Atomic32* ptr);
-LinuxKernelCmpxchgFunc pLinuxKernelCmpxchg ATTRIBUTE_WEAK =
-    (LinuxKernelCmpxchgFunc) 0xffff0fc0;
-
-typedef void (*LinuxKernelMemoryBarrierFunc)(void);
-LinuxKernelMemoryBarrierFunc pLinuxKernelMemoryBarrier ATTRIBUTE_WEAK =
-    (LinuxKernelMemoryBarrierFunc) 0xffff0fa0;
-
-
-inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr,
-                                         Atomic32 old_value,
-                                         Atomic32 new_value) {
-  Atomic32 prev_value = *ptr;
-  do {
-    if (!pLinuxKernelCmpxchg(old_value, new_value,
-                             const_cast<Atomic32*>(ptr))) {
-      return old_value;
-    }
-    prev_value = *ptr;
-  } while (prev_value == old_value);
-  return prev_value;
-}
-
-inline Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr,
-                                         Atomic32 new_value) {
-  Atomic32 old_value;
-  do {
-    old_value = *ptr;
-  } while (pLinuxKernelCmpxchg(old_value, new_value,
-                               const_cast<Atomic32*>(ptr)));
-  return old_value;
-}
-
-inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr,
-                                        Atomic32 increment) {
-  for (;;) {
-    // Atomic exchange the old value with an incremented one.
-    Atomic32 old_value = *ptr;
-    Atomic32 new_value = old_value + increment;
-    if (pLinuxKernelCmpxchg(old_value, new_value,
-                            const_cast<Atomic32*>(ptr)) == 0) {
-      // The exchange took place as expected.
-      return new_value;
-    }
-    // Otherwise, *ptr changed mid-loop and we need to retry.
-  }
-}
-
-inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr,
-                                          Atomic32 increment) {
-  return Barrier_AtomicIncrement(ptr, increment);
-}
-
-inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr,
-                                       Atomic32 old_value,
-                                       Atomic32 new_value) {
-  return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
-}
-
-inline Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
-                                       Atomic32 old_value,
-                                       Atomic32 new_value) {
-  return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
-}
-
-inline void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value) {
-  *ptr = value;
-}
-
-inline void MemoryBarrier() {
-  pLinuxKernelMemoryBarrier();
-}
-
-inline void Acquire_Store(volatile Atomic32* ptr, Atomic32 value) {
-  *ptr = value;
-  MemoryBarrier();
-}
-
-inline void Release_Store(volatile Atomic32* ptr, Atomic32 value) {
-  MemoryBarrier();
-  *ptr = value;
-}
-
-inline Atomic32 NoBarrier_Load(volatile const Atomic32* ptr) {
-  return *ptr;
-}
-
-inline Atomic32 Acquire_Load(volatile const Atomic32* ptr) {
-  Atomic32 value = *ptr;
-  MemoryBarrier();
-  return value;
-}
-
-inline Atomic32 Release_Load(volatile const Atomic32* ptr) {
-  MemoryBarrier();
-  return *ptr;
-}
-
-
-// 64-bit versions are not implemented yet.
-
-inline void NotImplementedFatalError(const char *function_name) {
-  fprintf(stderr, "64-bit %s() not implemented on this platform\n",
-          function_name);
-  tcmalloc::Abort();
-}
-
-inline Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr,
-                                         Atomic64 old_value,
-                                         Atomic64 new_value) {
-  NotImplementedFatalError("NoBarrier_CompareAndSwap");
-  return 0;
-}
-
-inline Atomic64 NoBarrier_AtomicExchange(volatile Atomic64* ptr,
-                                         Atomic64 new_value) {
-  NotImplementedFatalError("NoBarrier_AtomicExchange");
-  return 0;
-}
-
-inline Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr,
-                                          Atomic64 increment) {
-  NotImplementedFatalError("NoBarrier_AtomicIncrement");
-  return 0;
-}
-
-inline Atomic64 Barrier_AtomicIncrement(volatile Atomic64* ptr,
-                                        Atomic64 increment) {
-  NotImplementedFatalError("Barrier_AtomicIncrement");
-  return 0;
-}
-
-inline void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value) {
-  NotImplementedFatalError("NoBarrier_Store");
-}
-
-inline void Acquire_Store(volatile Atomic64* ptr, Atomic64 value) {
-  NotImplementedFatalError("Acquire_Store64");
-}
-
-inline void Release_Store(volatile Atomic64* ptr, Atomic64 value) {
-  NotImplementedFatalError("Release_Store");
-}
-
-inline Atomic64 NoBarrier_Load(volatile const Atomic64* ptr) {
-  NotImplementedFatalError("NoBarrier_Load");
-  return 0;
-}
-
-inline Atomic64 Acquire_Load(volatile const Atomic64* ptr) {
-  NotImplementedFatalError("Atomic64 Acquire_Load");
-  return 0;
-}
-
-inline Atomic64 Release_Load(volatile const Atomic64* ptr) {
-  NotImplementedFatalError("Atomic64 Release_Load");
-  return 0;
-}
-
-inline Atomic64 Acquire_CompareAndSwap(volatile Atomic64* ptr,
-                                       Atomic64 old_value,
-                                       Atomic64 new_value) {
-  NotImplementedFatalError("Atomic64 Acquire_CompareAndSwap");
-  return 0;
-}
-
-inline Atomic64 Release_CompareAndSwap(volatile Atomic64* ptr,
-                                       Atomic64 old_value,
-                                       Atomic64 new_value) {
-  NotImplementedFatalError("Atomic64 Release_CompareAndSwap");
-  return 0;
-}
-
-}  // namespace base::subtle
-}  // namespace base
-
-#endif  // BASE_ATOMICOPS_INTERNALS_ARM_GENERIC_H_