New atomic operation foundation code and interfaces. Based on the atomic operations in google-perftools / tcmalloc.

- Makes atomic operations cross-platform (win/mac/linux).
- Supports 64 bit operations on 64 bit processors.
- Make atomic operations more correct on Windows (barriers).
- Introduces a better / safer interface, and abstracts away most common atomic operations, reference counting and sequence numbers.

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@370 0039d316-1c4b-4281-b951-d872f2087c98

7 files changed, 1206 insertions, 0 deletions

diff --git a/base/atomic_ref_count.h b/base/atomic_ref_count.h
new file mode 100644
index 0000000..84bd343
--- /dev/null
+++ b/base/atomic_ref_count.h
@@ -0,0 +1,89 @@
+// Copyright 2008, 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.
+
+// This is a low level implementation of atomic semantics for reference
+// counting.  Please use base/ref_counted.h directly instead.
+
+#ifndef BASE_ATOMIC_REF_COUNT_H_
+#define BASE_ATOMIC_REF_COUNT_H_
+
+#include "base/atomicops.h"
+#include "base/basictypes.h"
+
+namespace base {
+
+typedef base::subtle::Atomic32 AtomicRefCount;
+
+// Increment a reference count by "increment", which must exceed 0.
+inline void AtomicRefCountIncN(volatile AtomicRefCount *ptr,
+                               AtomicRefCount increment) {
+  base::subtle::NoBarrier_AtomicIncrement(ptr, increment);
+}
+
+// Decrement a reference count by "decrement", which must exceed 0,
+// and return whether the result is non-zero.
+// Insert barriers to ensure that state written before the reference count
+// became zero will be visible to a thread that has just made the count zero.
+inline bool AtomicRefCountDecN(volatile AtomicRefCount *ptr,
+                               AtomicRefCount decrement) {
+  return base::subtle::Barrier_AtomicIncrement(ptr, -decrement) != 0;
+}
+
+// Increment a reference count by 1.
+inline void AtomicRefCountInc(volatile AtomicRefCount *ptr) {
+  base::AtomicRefCountIncN(ptr, 1);
+}
+
+// Decrement a reference count by 1 and return whether the result is non-zero.
+// Insert barriers to ensure that state written before the reference count
+// became zero will be visible to a thread that has just made the count zero.
+inline bool AtomicRefCountDec(volatile AtomicRefCount *ptr) {
+  return base::AtomicRefCountDecN(ptr, 1);
+}
+
+// Return whether the reference count is one.  If the reference count is used
+// in the conventional way, a refrerence count of 1 implies that the current
+// thread owns the reference and no other thread shares it.  This call performs
+// the test for a reference count of one, and performs the memory barrier
+// needed for the owning thread to act on the object, knowing that it has
+// exclusive access to the object.
+inline bool AtomicRefCountIsOne(volatile AtomicRefCount *ptr) {
+  return base::subtle::Acquire_Load(ptr) == 1;
+}
+
+// Return whether the reference count is zero.  With conventional object
+// referencing counting, the object will be destroyed, so the reference count
+// should never be zero.  Hence this is generally used for a debug check.
+inline bool AtomicRefCountIsZero(volatile AtomicRefCount *ptr) {
+  return base::subtle::Acquire_Load(ptr) == 0;
+}
+
+}  // namespace base
+
+#endif  // BASE_ATOMIC_REF_COUNT_H_
diff --git a/base/atomic_sequence_num.h b/base/atomic_sequence_num.h
new file mode 100644
index 0000000..d1ce303f
--- /dev/null
+++ b/base/atomic_sequence_num.h
@@ -0,0 +1,54 @@
+// Copyright 2008, 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.
+
+#ifndef BASE_ATOMIC_SEQUENCE_NUM_H_
+#define BASE_ATOMIC_SEQUENCE_NUM_H_
+
+#include "base/atomicops.h"
+#include "base/basictypes.h"
+
+namespace base {
+
+class AtomicSequenceNumber {
+ public:
+  AtomicSequenceNumber() : seq_(0) { }
+
+  int GetNext() {
+    return static_cast<int>(
+        base::subtle::NoBarrier_AtomicIncrement(&seq_, 1) - 1);
+  }
+
+ private:
+  base::subtle::Atomic32 seq_;
+  DISALLOW_COPY_AND_ASSIGN(AtomicSequenceNumber);
+};
+
+}  // namespace base
+
+#endif  // BASE_ATOMIC_SEQUENCE_NUM_H_
diff --git a/base/atomicops.h b/base/atomicops.h
new file mode 100644
index 0000000..e67c51a
--- /dev/null
+++ b/base/atomicops.h
@@ -0,0 +1,165 @@
+// Copyright 2008, 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.
+
+// For atomic operations on reference counts, see atomic_refcount.h.
+// For atomic operations on sequence numbers, see atomic_sequence_num.h.
+
+// The routines exported by this module are subtle.  If you use them, even if
+// you get the code right, it will depend on careful reasoning about atomicity
+// and memory ordering; it will be less readable, and harder to maintain.  If
+// you plan to use these routines, you should have a good reason, such as solid
+// evidence that performance would otherwise suffer, or there being no
+// alternative.  You should assume only properties explicitly guaranteed by the
+// specifications in this file.  You are almost certainly _not_ writing code
+// just for the x86; if you assume x86 semantics, x86 hardware bugs and
+// implementations on other archtectures will cause your code to break.  If you
+// do not know what you are doing, avoid these routines, and use a Mutex.
+//
+// It is incorrect to make direct assignments to/from an atomic variable.
+// You should use one of the Load or Store routines.  The NoBarrier
+// versions are provided when no barriers are needed:
+//   NoBarrier_Store()
+//   NoBarrier_Load()
+// Although there are currently no compiler enforcement, you are encouraged
+// to use these.
+//
+
+#ifndef BASE_ATOMICOPS_H_
+#define BASE_ATOMICOPS_H_
+
+#include "base/basictypes.h"
+
+#if defined(_WIN64) || defined(__x86_64__) || defined(__LP64)
+#define HAS_64_BIT
+#endif
+#ifndef WIN32
+#define __w64
+#endif
+
+namespace base {
+namespace subtle {
+
+// Bug 1308991.  We need this for /Wp64, to mark it safe for AtomicWord casting.
+typedef __w64 int32 Atomic32;
+#ifdef HAS_64_BIT
+typedef int64 Atomic64;
+#endif
+
+// Use AtomicWord for a machine-sized pointer.  It will use the Atomic32 or
+// Atomic64 routines below, depending on your architecture.
+typedef intptr_t AtomicWord;
+
+// Atomically execute:
+//      result = *ptr;
+//      if (*ptr == old_value)
+//        *ptr = new_value;
+//      return result;
+//
+// I.e., replace "*ptr" with "new_value" if "*ptr" used to be "old_value".
+// Always return the old value of "*ptr"
+//
+// This routine implies no memory barriers.
+Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr,
+                                  Atomic32 old_value,
+                                  Atomic32 new_value);
+
+// Atomically store new_value into *ptr, returning the previous value held in
+// *ptr.  This routine implies no memory barriers.
+Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr, Atomic32 new_value);
+
+// Atomically increment *ptr by "increment".  Returns the new value of
+// *ptr with the increment applied.  This routine implies no memory barriers.
+Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr, Atomic32 increment);
+
+Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr,
+                                 Atomic32 increment);
+
+// These following lower-level operations are typically useful only to people
+// implementing higher-level synchronization operations like spinlocks,
+// mutexes, and condition-variables.  They combine CompareAndSwap(), a load, or
+// a store with appropriate memory-ordering instructions.  "Acquire" operations
+// ensure that no later memory access can be reordered ahead of the operation.
+// "Release" operations ensure that no previous memory access can be reordered
+// after the operation.  "Barrier" operations have both "Acquire" and "Release"
+// semantics.   A MemoryBarrier() has "Barrier" semantics, but does no memory
+// access.
+Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr,
+                                Atomic32 old_value,
+                                Atomic32 new_value);
+Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
+                                Atomic32 old_value,
+                                Atomic32 new_value);
+
+void MemoryBarrier();
+void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value);
+void Acquire_Store(volatile Atomic32* ptr, Atomic32 value);
+void Release_Store(volatile Atomic32* ptr, Atomic32 value);
+
+Atomic32 NoBarrier_Load(volatile const Atomic32* ptr);
+Atomic32 Acquire_Load(volatile const Atomic32* ptr);
+Atomic32 Release_Load(volatile const Atomic32* ptr);
+
+// 64-bit atomic operations (only available on 64-bit processors).
+#ifdef HAS_64_BIT
+Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr,
+                                  Atomic64 old_value,
+                                  Atomic64 new_value);
+Atomic64 NoBarrier_AtomicExchange(volatile Atomic64* ptr, Atomic64 new_value);
+Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr, Atomic64 increment);
+Atomic64 Barrier_AtomicIncrement(volatile Atomic64* ptr, Atomic64 increment);
+
+Atomic64 Acquire_CompareAndSwap(volatile Atomic64* ptr,
+                                Atomic64 old_value,
+                                Atomic64 new_value);
+Atomic64 Release_CompareAndSwap(volatile Atomic64* ptr,
+                                Atomic64 old_value,
+                                Atomic64 new_value);
+void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value);
+void Acquire_Store(volatile Atomic64* ptr, Atomic64 value);
+void Release_Store(volatile Atomic64* ptr, Atomic64 value);
+Atomic64 NoBarrier_Load(volatile const Atomic64* ptr);
+Atomic64 Acquire_Load(volatile const Atomic64* ptr);
+Atomic64 Release_Load(volatile const Atomic64* ptr);
+#endif  // HAS_64_bit
+
+}  // namespace base::subtle
+}  // namespace base
+
+// Include our platform specific implementation.
+#if defined(_MSC_VER) && defined(_M_IX86)
+#include "base/atomicops_internals_x86_msvc.h"
+#elif defined(__MACH__) && defined(__APPLE__) && defined(__i386__)
+#include "base/atomicops_internals_x86_macosx.h"
+#elif defined(__GNUC__) &&  (defined(__i386) || defined(ARCH_K8))
+#include "base/atomicops_internals_x86_gcc.h"
+#else
+#error "Atomic operations are not supported on your platform"
+#endif
+
+#endif  // BASE_ATOMICOPS_H_
diff --git a/base/atomicops_internals_x86_gcc.cc b/base/atomicops_internals_x86_gcc.cc
new file mode 100644
index 0000000..64b6207
--- /dev/null
+++ b/base/atomicops_internals_x86_gcc.cc
@@ -0,0 +1,129 @@
+// Copyright 2008, 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.
+
+// This module gets enough CPU information to optimize the
+// atomicops module on x86.
+
+#include <string.h>
+
+#include "base/atomicops.h"
+#include "base/basictypes.h"
+
+// This file only makes sense with atomicops_internals_x86_gcc.h -- it
+// depends on structs that are defined in that file.  If atomicops.h
+// doesn't sub-include that file, then we aren't needed, and shouldn't
+// try to do anything.
+#ifdef BASE_ATOMICOPS_INTERNALS_X86_GCC_H_
+
+// Inline cpuid instruction.  In PIC compilations, %ebx contains the address
+// of the global offset table.  To avoid breaking such executables, this code
+// must preserve that register's value across cpuid instructions.
+#if defined(__i386__)
+#define cpuid(a, b, c, d, inp) \
+  asm ("mov %%ebx, %%edi\n"    \
+       "cpuid\n"               \
+       "xchg %%edi, %%ebx\n"   \
+       : "=a" (a), "=D" (b), "=c" (c), "=d" (d) : "a" (inp))
+#elif defined (__x86_64__)
+#define cpuid(a, b, c, d, inp) \
+  asm ("mov %%rbx, %%rdi\n"    \
+       "cpuid\n"               \
+       "xchg %%rdi, %%rbx\n"   \
+       : "=a" (a), "=D" (b), "=c" (c), "=d" (d) : "a" (inp))
+#endif
+
+#if defined(cpuid)        // initialize the struct only on x86
+
+// Set the flags so that code will run correctly and conservatively, so even
+// if we haven't been initialized yet, we're probably single threaded, and our
+// default values should hopefully be pretty safe.
+struct AtomicOps_x86CPUFeatureStruct AtomicOps_Internalx86CPUFeatures = {
+  false,          // bug can't exist before process spawns multiple threads
+  false,          // no SSE2
+};
+
+// Initialize the AtomicOps_Internalx86CPUFeatures struct.
+static void AtomicOps_Internalx86CPUFeaturesInit() {
+  uint32 eax;
+  uint32 ebx;
+  uint32 ecx;
+  uint32 edx;
+
+  // Get vendor string (issue CPUID with eax = 0)
+  cpuid(eax, ebx, ecx, edx, 0);
+  char vendor[13];
+  memcpy(vendor, &ebx, 4);
+  memcpy(vendor + 4, &edx, 4);
+  memcpy(vendor + 8, &ecx, 4);
+  vendor[12] = 0;
+
+  // get feature flags in ecx/edx, and family/model in eax
+  cpuid(eax, ebx, ecx, edx, 1);
+
+  int family = (eax >> 8) & 0xf;        // family and model fields
+  int model = (eax >> 4) & 0xf;
+  if (family == 0xf) {                  // use extended family and model fields
+    family += (eax >> 20) & 0xff;
+    model += ((eax >> 16) & 0xf) << 4;
+  }
+
+  // Opteron Rev E has a bug in which on very rare occasions a locked
+  // instruction doesn't act as a read-acquire barrier if followed by a
+  // non-locked read-modify-write instruction.  Rev F has this bug in 
+  // pre-release versions, but not in versions released to customers,
+  // so we test only for Rev E, which is family 15, model 32..63 inclusive.
+  if (strcmp(vendor, "AuthenticAMD") == 0 &&       // AMD
+      family == 15 &&
+      32 <= model && model <= 63) {
+    AtomicOps_Internalx86CPUFeatures.has_amd_lock_mb_bug = true;
+  } else {
+    AtomicOps_Internalx86CPUFeatures.has_amd_lock_mb_bug = false;
+  }
+
+  // edx bit 26 is SSE2 which we use to tell use whether we can use mfence
+  AtomicOps_Internalx86CPUFeatures.has_sse2 = ((edx >> 26) & 1);
+}
+
+namespace {
+
+class AtomicOpsx86Initializer {
+ public:
+  AtomicOpsx86Initializer() {
+    AtomicOps_Internalx86CPUFeaturesInit();
+  }
+};
+
+// A global to get use initialized on startup via static initialization :/
+AtomicOpsx86Initializer g_initer;
+
+}  // namespace
+
+#endif  // if x86
+
+#endif  // ifdef BASE_ATOMICOPS_INTERNALS_X86_GCC_H_
diff --git a/base/atomicops_internals_x86_gcc.h b/base/atomicops_internals_x86_gcc.h
new file mode 100644
index 0000000..c0507e9
--- /dev/null
+++ b/base/atomicops_internals_x86_gcc.h
@@ -0,0 +1,273 @@
+// Copyright 2008, 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.
+
+// This file is an internal atomic implementation, use base/atomicops.h instead.
+
+#ifndef BASE_ATOMICOPS_INTERNALS_X86_GCC_H_
+#define BASE_ATOMICOPS_INTERNALS_X86_GCC_H_
+
+// This struct is not part of the public API of this module; clients may not
+// use it.
+// Features of this x86.  Values may not be correct before main() is run,
+// but are set conservatively.
+struct AtomicOps_x86CPUFeatureStruct {
+  bool has_amd_lock_mb_bug; // Processor has AMD memory-barrier bug; do lfence
+                            // after acquire compare-and-swap.
+  bool has_sse2;            // Processor has SSE2.
+};
+extern struct AtomicOps_x86CPUFeatureStruct AtomicOps_Internalx86CPUFeatures;
+
+#define ATOMICOPS_COMPILER_BARRIER() __asm__ __volatile__("" : : : "memory")
+
+namespace base {
+namespace subtle {
+
+// 32-bit low-level operations on any platform.
+
+inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr,
+                                         Atomic32 old_value,
+                                         Atomic32 new_value) {
+  Atomic32 prev;
+  __asm__ __volatile__("lock; cmpxchgl %1,%2"
+                       : "=a" (prev)
+                       : "q" (new_value), "m" (*ptr), "0" (old_value)
+                       : "memory");
+  return prev;
+}
+
+inline Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr,
+                                         Atomic32 new_value) {
+  __asm__ __volatile__("xchgl %1,%0"  // The lock prefix is implicit for xchg.
+                       : "=r" (new_value)
+                       : "m" (*ptr), "0" (new_value)
+                       : "memory");
+  return new_value;  // Now it's the previous value.
+}
+
+inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr,
+                                          Atomic32 increment) {
+  Atomic32 temp = increment;
+  __asm__ __volatile__("lock; xaddl %0,%1"
+                       : "+r" (temp), "+m" (*ptr)
+                       : : "memory");
+  // temp now holds the old value of *ptr
+  return temp + increment;
+}
+
+inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr,
+                                        Atomic32 increment) {
+  Atomic32 temp = increment;
+  __asm__ __volatile__("lock; xaddl %0,%1"
+                       : "+r" (temp), "+m" (*ptr)
+                       : : "memory");
+  // temp now holds the old value of *ptr
+  if (AtomicOps_Internalx86CPUFeatures.has_amd_lock_mb_bug) {
+    __asm__ __volatile__("lfence" : : : "memory");
+  }
+  return temp + increment;
+}
+
+inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr,
+                                       Atomic32 old_value,
+                                       Atomic32 new_value) {
+  Atomic32 x = NoBarrier_CompareAndSwap(ptr, old_value, new_value);
+  if (AtomicOps_Internalx86CPUFeatures.has_amd_lock_mb_bug) {
+    __asm__ __volatile__("lfence" : : : "memory");
+  }
+  return x;
+}
+
+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;
+}
+
+#if defined(__x86_64__)
+
+// 64-bit implementations of memory barrier can be simpler, because it
+// "mfence" is guaranteed to exist.
+inline void MemoryBarrier() {
+  __asm__ __volatile__("mfence" : : : "memory");
+}
+
+inline void Acquire_Store(volatile Atomic32* ptr, Atomic32 value) {
+  *ptr = value;
+  MemoryBarrier();
+}
+
+#else
+
+inline void MemoryBarrier() {
+  if (AtomicOps_Internalx86CPUFeatures.has_sse2) {
+    __asm__ __volatile__("mfence" : : : "memory");
+  } else { // mfence is faster but not present on PIII
+    Atomic32 x = 0;
+    NoBarrier_AtomicExchange(&x, 0);  // acts as a barrier on PIII
+  }
+}
+
+inline void Acquire_Store(volatile Atomic32* ptr, Atomic32 value) {
+  if (AtomicOps_Internalx86CPUFeatures.has_sse2) {
+    *ptr = value;
+    __asm__ __volatile__("mfence" : : : "memory");
+  } else {
+    NoBarrier_AtomicExchange(ptr, value);
+                          // acts as a barrier on PIII
+  }
+}
+#endif
+
+inline void Release_Store(volatile Atomic32* ptr, Atomic32 value) {
+  ATOMICOPS_COMPILER_BARRIER();
+  *ptr = value; // An x86 store acts as a release barrier.
+  // See comments in Atomic64 version of Release_Store(), below.
+}
+
+inline Atomic32 NoBarrier_Load(volatile const Atomic32* ptr) {
+  return *ptr;
+}
+
+inline Atomic32 Acquire_Load(volatile const Atomic32* ptr) {
+  Atomic32 value = *ptr; // An x86 load acts as a acquire barrier.
+  // See comments in Atomic64 version of Release_Store(), below.
+  ATOMICOPS_COMPILER_BARRIER();
+  return value;
+}
+
+inline Atomic32 Release_Load(volatile const Atomic32* ptr) {
+  MemoryBarrier();
+  return *ptr;
+}
+
+#if defined(__x86_64__)
+
+// 64-bit low-level operations on 64-bit platform.
+
+inline Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr,
+                                         Atomic64 old_value,
+                                         Atomic64 new_value) {
+  Atomic64 prev;
+  __asm__ __volatile__("lock; cmpxchgq %1,%2"
+                       : "=a" (prev)
+                       : "q" (new_value), "m" (*ptr), "0" (old_value)
+                       : "memory");
+  return prev;
+}
+
+inline Atomic64 NoBarrier_AtomicExchange(volatile Atomic64* ptr,
+                                         Atomic64 new_value) {
+  __asm__ __volatile__("xchgq %1,%0"  // The lock prefix is implicit for xchg.
+                       : "=r" (new_value)
+                       : "m" (*ptr), "0" (new_value)
+                       : "memory");
+  return new_value;  // Now it's the previous value.
+}
+
+inline Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr,
+                                          Atomic64 increment) {
+  Atomic64 temp = increment;
+  __asm__ __volatile__("lock; xaddq %0,%1"
+                       : "+r" (temp), "+m" (*ptr)
+                       : : "memory");
+  // temp now contains the previous value of *ptr
+  return temp + increment;
+}
+
+inline Atomic64 Barrier_AtomicIncrement(volatile Atomic64* ptr,
+                                        Atomic64 increment) {
+  Atomic64 temp = increment;
+  __asm__ __volatile__("lock; xaddq %0,%1"
+                       : "+r" (temp), "+m" (*ptr)
+                       : : "memory");
+  // temp now contains the previous value of *ptr
+  if (AtomicOps_Internalx86CPUFeatures.has_amd_lock_mb_bug) {
+    __asm__ __volatile__("lfence" : : : "memory");
+  }
+  return temp + increment;
+}
+
+inline void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value) {
+  *ptr = value;
+}
+
+inline void Acquire_Store(volatile Atomic64* ptr, Atomic64 value) {
+  *ptr = value;
+  MemoryBarrier();
+}
+
+inline void Release_Store(volatile Atomic64* ptr, Atomic64 value) {
+  ATOMICOPS_COMPILER_BARRIER();
+
+  *ptr = value; // An x86 store acts as a release barrier
+                // for current AMD/Intel chips as of Jan 2008.
+                // See also Acquire_Load(), below.
+
+  // When new chips come out, check:
+  //  IA-32 Intel Architecture Software Developer's Manual, Volume 3:
+  //  System Programming Guide, Chatper 7: Multiple-processor management,
+  //  Section 7.2, Memory Ordering.
+  // Last seen at:
+  //   http://developer.intel.com/design/pentium4/manuals/index_new.htm
+  //
+  // x86 stores/loads fail to act as barriers for a few instructions (clflush
+  // maskmovdqu maskmovq movntdq movnti movntpd movntps movntq) but these are
+  // not generated by the compiler, and are rare.  Users of these instructions
+  // need to know about cache behaviour in any case since all of these involve
+  // either flushing cache lines or non-temporal cache hints.
+}
+
+inline Atomic64 NoBarrier_Load(volatile const Atomic64* ptr) {
+  return *ptr;
+}
+
+inline Atomic64 Acquire_Load(volatile const Atomic64* ptr) {
+  Atomic64 value = *ptr; // An x86 load acts as a acquire barrier,
+                         // for current AMD/Intel chips as of Jan 2008.
+                         // See also Release_Store(), above.
+  ATOMICOPS_COMPILER_BARRIER();
+  return value;
+}
+
+inline Atomic64 Release_Load(volatile const Atomic64* ptr) {
+  MemoryBarrier();
+  return *ptr;
+}
+#endif  // defined(__x86_64__)
+
+} // namespace base::subtle
+} // namespace base
+
+#undef ATOMICOPS_COMPILER_BARRIER
+
+#endif  // BASE_ATOMICOPS_INTERNALS_X86_GCC_H_
diff --git a/base/atomicops_internals_x86_macosx.h b/base/atomicops_internals_x86_macosx.h
new file mode 100644
index 0000000..9bad5f6
--- /dev/null
+++ b/base/atomicops_internals_x86_macosx.h
@@ -0,0 +1,304 @@
+// Copyright 2008, 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.
+
+// This file is an internal atomic implementation, use base/atomicops.h instead.
+
+#ifndef BASE_ATOMICOPS_INTERNALS_X86_MACOSX_H_
+#define BASE_ATOMICOPS_INTERNALS_X86_MACOSX_H_
+
+#include <libkern/OSAtomic.h>
+
+namespace base {
+namespace subtle {
+
+inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32 *ptr,
+                                         Atomic32 old_value,
+                                         Atomic32 new_value) {
+  Atomic32 prev_value;
+  do {
+    if (OSAtomicCompareAndSwap32(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 (!OSAtomicCompareAndSwap32(old_value, new_value,
+                                     const_cast<Atomic32*>(ptr)));
+  return old_value;
+}
+
+inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32 *ptr,
+                                          Atomic32 increment) {
+  return OSAtomicAdd32(increment, const_cast<Atomic32*>(ptr));
+}
+
+inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32 *ptr,
+                                          Atomic32 increment) {
+  return OSAtomicAdd32Barrier(increment, const_cast<Atomic32*>(ptr));
+}
+
+inline void MemoryBarrier() {
+  OSMemoryBarrier();
+}
+
+inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32 *ptr,
+                                       Atomic32 old_value,
+                                       Atomic32 new_value) {
+  Atomic32 prev_value;
+  do {
+    if (OSAtomicCompareAndSwap32Barrier(old_value, new_value,
+                                        const_cast<Atomic32*>(ptr))) {
+      return old_value;
+    }
+    prev_value = *ptr;
+  } while (prev_value == old_value);
+  return prev_value;
+}
+
+inline Atomic32 Release_CompareAndSwap(volatile Atomic32 *ptr,
+                                       Atomic32 old_value,
+                                       Atomic32 new_value) {
+  return Acquire_CompareAndSwap(ptr, old_value, new_value);
+}
+
+inline void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value) {
+  *ptr = value;
+}
+
+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;
+}
+
+#ifdef __LP64__
+
+// 64-bit implementation on 64-bit platform
+
+inline Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64 *ptr,
+                                         Atomic64 old_value,
+                                         Atomic64 new_value) {
+  Atomic64 prev_value;
+  do {
+    if (OSAtomicCompareAndSwap64(old_value, new_value,
+                                 const_cast<Atomic64*>(ptr))) {
+      return old_value;
+    }
+    prev_value = *ptr;
+  } while (prev_value == old_value);
+  return prev_value;
+}
+
+inline Atomic64 NoBarrier_AtomicExchange(volatile Atomic64 *ptr,
+                                         Atomic64 new_value) {
+  Atomic64 old_value;
+  do {
+    old_value = *ptr;
+  } while (!OSAtomicCompareAndSwap64(old_value, new_value,
+                                     const_cast<Atomic64*>(ptr)));
+  return old_value;
+}
+
+inline Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64 *ptr,
+                                          Atomic64 increment) {
+  return OSAtomicAdd64(increment, const_cast<Atomic64*>(ptr));
+}
+
+inline Atomic64 Barrier_AtomicIncrement(volatile Atomic64 *ptr,
+                                        Atomic64 increment) {
+  return OSAtomicAdd64Barrier(increment, const_cast<Atomic64*>(ptr));
+}
+
+inline Atomic64 Acquire_CompareAndSwap(volatile Atomic64 *ptr,
+                                       Atomic64 old_value,
+                                       Atomic64 new_value) {
+  Atomic64 prev_value;
+  do {
+    if (OSAtomicCompareAndSwap64Barrier(old_value, new_value,
+                                        const_cast<Atomic64*>(ptr))) {
+      return old_value;
+    }
+    prev_value = *ptr;
+  } while (prev_value == old_value);
+  return prev_value;
+}
+
+inline Atomic64 Release_CompareAndSwap(volatile Atomic64 *ptr,
+                                       Atomic64 old_value,
+                                       Atomic64 new_value) {
+  // The lib kern interface does not distinguish between
+  // Acquire and Release memory barriers; they are equivalent.
+  return Acquire_CompareAndSwap(ptr, old_value, new_value);
+}
+
+inline void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value) {
+  *ptr = value;
+}
+
+inline void Acquire_Store(volatile Atomic64 *ptr, Atomic64 value) {
+  *ptr = value;
+  MemoryBarrier();
+}
+
+inline void Release_Store(volatile Atomic64 *ptr, Atomic64 value) {
+  MemoryBarrier();
+  *ptr = value;
+}
+
+inline Atomic64 NoBarrier_Load(volatile const Atomic64* ptr) {
+  return *ptr;
+}
+
+inline Atomic64 Acquire_Load(volatile const Atomic64 *ptr) {
+  Atomic64 value = *ptr;
+  MemoryBarrier();
+  return value;
+}
+
+inline Atomic64 Release_Load(volatile const Atomic64 *ptr) {
+  MemoryBarrier();
+  return *ptr;
+}
+
+#endif  // defined(__LP64__)
+
+// MacOS uses long for intptr_t, AtomicWord and Atomic32 are always different
+// on the Mac, even when they are the same size.  We need to explicitly cast
+// from AtomicWord to Atomic32/64 to implement the AtomicWord interface.
+#ifdef __LP64__
+#define AtomicWordCastType Atomic64
+#else
+#define AtomicWordCastType Atomic32
+#endif
+
+inline AtomicWord NoBarrier_CompareAndSwap(volatile AtomicWord* ptr,
+                                           AtomicWord old_value,
+                                           AtomicWord new_value) {
+  return NoBarrier_CompareAndSwap(
+      reinterpret_cast<volatile AtomicWordCastType*>(ptr),
+      old_value, new_value);
+}
+
+inline AtomicWord NoBarrier_AtomicExchange(volatile AtomicWord* ptr,
+                                           AtomicWord new_value) {
+  return NoBarrier_AtomicExchange(
+      reinterpret_cast<volatile AtomicWordCastType*>(ptr), new_value);
+}
+
+inline AtomicWord NoBarrier_AtomicIncrement(volatile AtomicWord* ptr,
+                                            AtomicWord increment) {
+  return NoBarrier_AtomicIncrement(
+      reinterpret_cast<volatile AtomicWordCastType*>(ptr), increment);
+}
+
+inline AtomicWord Barrier_AtomicIncrement(volatile AtomicWord* ptr,
+                                          AtomicWord increment) {
+  return Barrier_AtomicIncrement(
+      reinterpret_cast<volatile AtomicWordCastType*>(ptr), increment);
+}
+
+inline AtomicWord Acquire_CompareAndSwap(volatile AtomicWord* ptr,
+                                         AtomicWord old_value,
+                                         AtomicWord new_value) {
+  return base::subtle::Acquire_CompareAndSwap(
+      reinterpret_cast<volatile AtomicWordCastType*>(ptr),
+      old_value, new_value);
+}
+
+inline AtomicWord Release_CompareAndSwap(volatile AtomicWord* ptr,
+                                         AtomicWord old_value,
+                                         AtomicWord new_value) {
+  return base::subtle::Release_CompareAndSwap(
+      reinterpret_cast<volatile AtomicWordCastType*>(ptr),
+      old_value, new_value);
+}
+
+inline void NoBarrier_Store(volatile AtomicWord *ptr, AtomicWord value) {
+  NoBarrier_Store(
+      reinterpret_cast<volatile AtomicWordCastType*>(ptr), value);
+}
+
+inline void Acquire_Store(volatile AtomicWord* ptr, AtomicWord value) {
+  return base::subtle::Acquire_Store(
+      reinterpret_cast<volatile AtomicWordCastType*>(ptr), value);
+}
+
+inline void Release_Store(volatile AtomicWord* ptr, AtomicWord value) {
+  return base::subtle::Release_Store(
+      reinterpret_cast<volatile AtomicWordCastType*>(ptr), value);
+}
+
+inline AtomicWord NoBarrier_Load(volatile const AtomicWord *ptr) {
+  return NoBarrier_Load(
+      reinterpret_cast<volatile const AtomicWordCastType*>(ptr));
+}
+
+inline AtomicWord Acquire_Load(volatile const AtomicWord* ptr) {
+  return base::subtle::Acquire_Load(
+      reinterpret_cast<volatile const AtomicWordCastType*>(ptr));
+}
+
+inline AtomicWord Release_Load(volatile const AtomicWord* ptr) {
+  return base::subtle::Release_Load(
+      reinterpret_cast<volatile const AtomicWordCastType*>(ptr));
+}
+
+#undef AtomicWordCastType
+
+}   // namespace base::subtle
+}   // namespace base
+
+#endif  // BASE_ATOMICOPS_INTERNALS_X86_MACOSX_H_
diff --git a/base/atomicops_internals_x86_msvc.h b/base/atomicops_internals_x86_msvc.h
new file mode 100644
index 0000000..86f623e
--- /dev/null
+++ b/base/atomicops_internals_x86_msvc.h
@@ -0,0 +1,192 @@
+// Copyright 2008, 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.
+
+// This file is an internal atomic implementation, use base/atomicops.h instead.
+
+#ifndef BASE_ATOMICOPS_INTERNALS_X86_MSVC_H_
+#define BASE_ATOMICOPS_INTERNALS_X86_MSVC_H_
+
+#include <windows.h>
+
+namespace base {
+namespace subtle {
+
+inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr,
+                                         Atomic32 old_value,
+                                         Atomic32 new_value) {
+  LONG result = InterlockedCompareExchange(
+      reinterpret_cast<volatile LONG*>(ptr),
+      static_cast<LONG>(new_value),
+      static_cast<LONG>(old_value));
+  return static_cast<Atomic32>(result);
+}
+
+inline Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr,
+                                         Atomic32 new_value) {
+  LONG result = InterlockedExchange(
+      reinterpret_cast<volatile LONG*>(ptr),
+      static_cast<LONG>(new_value));
+  return static_cast<Atomic32>(result);
+}
+
+inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr,
+                                        Atomic32 increment) {
+  return InterlockedExchangeAdd(
+      reinterpret_cast<volatile LONG*>(ptr),
+      static_cast<LONG>(increment)) + increment;
+}
+
+inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr,
+                                          Atomic32 increment) {
+  return Barrier_AtomicIncrement(ptr, increment);
+}
+
+#if !(defined(_MSC_VER) && _MSC_VER >= 1400)
+#error "We require at least vs2005 for MemoryBarrier"
+#endif
+inline void MemoryBarrier() {
+  // We use MemoryBarrier from WinNT.h
+  ::MemoryBarrier();
+}
+
+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 Acquire_Store(volatile Atomic32* ptr, Atomic32 value) {
+  NoBarrier_AtomicExchange(ptr, value);
+              // acts as a barrier in this implementation
+}
+
+inline void Release_Store(volatile Atomic32* ptr, Atomic32 value) {
+  *ptr = value; // works w/o barrier for current Intel chips as of June 2005
+  // See comments in Atomic64 version of Release_Store() below.
+}
+
+inline Atomic32 NoBarrier_Load(volatile const Atomic32* ptr) {
+  return *ptr;
+}
+
+inline Atomic32 Acquire_Load(volatile const Atomic32* ptr) {
+  Atomic32 value = *ptr;
+  return value;
+}
+
+inline Atomic32 Release_Load(volatile const Atomic32* ptr) {
+  MemoryBarrier();
+  return *ptr;
+}
+
+#if defined(_WIN64)
+
+// 64-bit low-level operations on 64-bit platform.
+
+COMPILE_ASSERT(sizeof(Atomic64) == sizeof(PVOID), atomic_word_is_atomic);
+
+inline Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr,
+                                         Atomic64 old_value,
+                                         Atomic64 new_value) {
+  PVOID result = InterlockedCompareExchangePointer(
+    reinterpret_cast<volatile PVOID*>(ptr),
+    reinterpret_cast<PVOID>(new_value), reinterpret_cast<PVOID>(old_value));
+  return reinterpret_cast<Atomic64>(result);
+}
+
+inline Atomic64 NoBarrier_AtomicExchange(volatile Atomic64* ptr,
+                                         Atomic64 new_value) {
+  PVOID result = InterlockedExchangePointer(
+    reinterpret_cast<volatile PVOID*>(ptr),
+    reinterpret_cast<PVOID>(new_value));
+  return reinterpret_cast<Atomic64>(result);
+}
+
+inline Atomic64 Barrier_AtomicIncrement(volatile Atomic64* ptr,
+                                        Atomic64 increment) {
+  return InterlockedExchangeAdd64(
+      reinterpret_cast<volatile LONGLONG*>(ptr),
+      static_cast<LONGLONG>(increment)) + increment;
+}
+
+inline Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr,
+                                          Atomic64 increment) {
+  return Barrier_AtomicIncrement(ptr, increment);
+}
+
+inline void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value) {
+  *ptr = value;
+}
+
+inline void Acquire_Store(volatile Atomic64* ptr, Atomic64 value) {
+  NoBarrier_AtomicExchange(ptr, value);
+              // acts as a barrier in this implementation
+}
+
+inline void Release_Store(volatile Atomic64* ptr, Atomic64 value) {
+  *ptr = value; // works w/o barrier for current Intel chips as of June 2005
+
+  // When new chips come out, check:
+  //  IA-32 Intel Architecture Software Developer's Manual, Volume 3:
+  //  System Programming Guide, Chatper 7: Multiple-processor management,
+  //  Section 7.2, Memory Ordering.
+  // Last seen at:
+  //   http://developer.intel.com/design/pentium4/manuals/index_new.htm
+}
+
+inline Atomic64 NoBarrier_Load(volatile const Atomic64* ptr) {
+  return *ptr;
+}
+
+inline Atomic64 Acquire_Load(volatile const Atomic64* ptr) {
+  Atomic64 value = *ptr;
+  return value;
+}
+
+inline Atomic64 Release_Load(volatile const Atomic64* ptr) {
+  MemoryBarrier();
+  return *ptr;
+}
+
+#endif  // defined(_WIN64)
+
+}  // namespace base::subtle
+}  // namespace base
+
+#endif  // BASE_ATOMICOPS_INTERNALS_X86_MSVC_H_