Pull new version of protobuf sources.

third_party/protobuf/src/google/protobuf/stubs/atomicops_internals_pnacl.h

 // Protocol Buffers - Google's data interchange format
 // Copyright 2012 Google Inc.  All rights reserved.
-// http://code.google.com/p/protobuf/
+// https://developers.google.com/protocol-buffers/
 //
 // 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
@@ skipping 12 matching lines @@
 // 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 atomicops.h instead.
 
 #ifndef GOOGLE_PROTOBUF_ATOMICOPS_INTERNALS_PNACL_H_
 #define GOOGLE_PROTOBUF_ATOMICOPS_INTERNALS_PNACL_H_
 
+#include <atomic>
+
 namespace google {
 namespace protobuf {
 namespace internal {
 
+// This implementation is transitional and maintains the original API for
+// atomicops.h. This requires casting memory locations to the atomic types, and
+// assumes that the API and the C++11 implementation are layout-compatible,
+// which isn't true for all implementations or hardware platforms. The static
+// assertion should detect this issue, were it to fire then this header
+// shouldn't be used.
+//
+// TODO(jfb) If this header manages to stay committed then the API should be
+//           modified, and all call sites updated.
+typedef volatile std::atomic<Atomic32>* AtomicLocation32;
+static_assert(sizeof(*(AtomicLocation32) nullptr) == sizeof(Atomic32),
+              "incompatible 32-bit atomic layout");
+
+inline void MemoryBarrier() {
+#if defined(__GLIBCXX__)
+  // Work around libstdc++ bug 51038 where atomic_thread_fence was declared but
+  // not defined, leading to the linker complaining about undefined references.
+  __atomic_thread_fence(std::memory_order_seq_cst);
+#else
+  std::atomic_thread_fence(std::memory_order_seq_cst);
+#endif
+}
+
 inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr,
                                          Atomic32 old_value,
                                          Atomic32 new_value) {
-  return __sync_val_compare_and_swap(ptr, old_value, new_value);
+  ((AtomicLocation32)ptr)
+      ->compare_exchange_strong(old_value,
+                                new_value,
+                                std::memory_order_relaxed,
+                                std::memory_order_relaxed);
+  return old_value;
 }
 
-inline void MemoryBarrier() {
-  __sync_synchronize();
+inline Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr,
+                                         Atomic32 new_value) {
+  return ((AtomicLocation32)ptr)
+      ->exchange(new_value, std::memory_order_relaxed);
+}
+
+inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr,
+                                          Atomic32 increment) {
+  return increment +
+         ((AtomicLocation32)ptr)
+             ->fetch_add(increment, std::memory_order_relaxed);
+}
+
+inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr,
+                                        Atomic32 increment) {
+  return increment + ((AtomicLocation32)ptr)->fetch_add(increment);
 }
 
 inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr,
                                        Atomic32 old_value,
                                        Atomic32 new_value) {
-  Atomic32 ret = NoBarrier_CompareAndSwap(ptr, old_value, new_value);
+  ((AtomicLocation32)ptr)
+      ->compare_exchange_strong(old_value,
+                                new_value,
+                                std::memory_order_acquire,
+                                std::memory_order_acquire);
+  return old_value;
+}
+
+inline Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
+                                       Atomic32 old_value,
+                                       Atomic32 new_value) {
+  ((AtomicLocation32)ptr)
+      ->compare_exchange_strong(old_value,
+                                new_value,
+                                std::memory_order_release,
+                                std::memory_order_relaxed);
+  return old_value;
+}
+
+inline void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value) {
+  ((AtomicLocation32)ptr)->store(value, std::memory_order_relaxed);
+}
+
+inline void Acquire_Store(volatile Atomic32* ptr, Atomic32 value) {
+  ((AtomicLocation32)ptr)->store(value, std::memory_order_relaxed);
   MemoryBarrier();
-  return ret;
 }
 
 inline void Release_Store(volatile Atomic32* ptr, Atomic32 value) {
-  MemoryBarrier();
-  *ptr = value;
+  ((AtomicLocation32)ptr)->store(value, std::memory_order_release);
+}
+
+inline Atomic32 NoBarrier_Load(volatile const Atomic32* ptr) {
+  return ((AtomicLocation32)ptr)->load(std::memory_order_relaxed);
 }
 
 inline Atomic32 Acquire_Load(volatile const Atomic32* ptr) {
-  Atomic32 value = *ptr;
+  return ((AtomicLocation32)ptr)->load(std::memory_order_acquire);
+}
+
+inline Atomic32 Release_Load(volatile const Atomic32* ptr) {
   MemoryBarrier();
-  return value;
+  return ((AtomicLocation32)ptr)->load(std::memory_order_relaxed);
 }
 
+#if defined(GOOGLE_PROTOBUF_ARCH_64_BIT)
+
+typedef volatile std::atomic<Atomic64>* AtomicLocation64;
+static_assert(sizeof(*(AtomicLocation64) nullptr) == sizeof(Atomic64),
+              "incompatible 64-bit atomic layout");
+
+inline Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr,
+                                         Atomic64 old_value,
+                                         Atomic64 new_value) {
+  ((AtomicLocation64)ptr)
+      ->compare_exchange_strong(old_value,
+                                new_value,
+                                std::memory_order_relaxed,
+                                std::memory_order_relaxed);
+  return old_value;
+}
+
+inline Atomic64 NoBarrier_AtomicExchange(volatile Atomic64* ptr,
+                                         Atomic64 new_value) {
+  return ((AtomicLocation64)ptr)
+      ->exchange(new_value, std::memory_order_relaxed);
+}
+
+inline Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr,
+                                          Atomic64 increment) {
+  return increment +
+         ((AtomicLocation64)ptr)
+             ->fetch_add(increment, std::memory_order_relaxed);
+}
+
+inline Atomic64 Barrier_AtomicIncrement(volatile Atomic64* ptr,
+                                        Atomic64 increment) {
+  return increment + ((AtomicLocation64)ptr)->fetch_add(increment);
+}
+
+inline Atomic64 Acquire_CompareAndSwap(volatile Atomic64* ptr,
+                                       Atomic64 old_value,
+                                       Atomic64 new_value) {
+  ((AtomicLocation64)ptr)
+      ->compare_exchange_strong(old_value,
+                                new_value,
+                                std::memory_order_acquire,
+                                std::memory_order_acquire);
+  return old_value;
+}
+
+inline Atomic64 Release_CompareAndSwap(volatile Atomic64* ptr,
+                                       Atomic64 old_value,
+                                       Atomic64 new_value) {
+  ((AtomicLocation64)ptr)
+      ->compare_exchange_strong(old_value,
+                                new_value,
+                                std::memory_order_release,
+                                std::memory_order_relaxed);
+  return old_value;
+}
+
+inline void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value) {
+  ((AtomicLocation64)ptr)->store(value, std::memory_order_relaxed);
+}
+
+inline void Acquire_Store(volatile Atomic64* ptr, Atomic64 value) {
+  ((AtomicLocation64)ptr)->store(value, std::memory_order_relaxed);
+  MemoryBarrier();
+}
+
+inline void Release_Store(volatile Atomic64* ptr, Atomic64 value) {
+  ((AtomicLocation64)ptr)->store(value, std::memory_order_release);
+}
+
+inline Atomic64 NoBarrier_Load(volatile const Atomic64* ptr) {
+  return ((AtomicLocation64)ptr)->load(std::memory_order_relaxed);
+}
+
+inline Atomic64 Acquire_Load(volatile const Atomic64* ptr) {
+  return ((AtomicLocation64)ptr)->load(std::memory_order_acquire);
+}
+
+inline Atomic64 Release_Load(volatile const Atomic64* ptr) {
+  MemoryBarrier();
+  return ((AtomicLocation64)ptr)->load(std::memory_order_relaxed);
+}
+
+#endif  // defined(GOOGLE_PROTOBUF_ARCH_64_BIT)
+
 }  // namespace internal
 }  // namespace protobuf
 }  // namespace google
 
 #endif  // GOOGLE_PROTOBUF_ATOMICOPS_INTERNALS_PNACL_H_