Convert runtime atomics functions to inline asm

src/runtime/runtime-atomics-intrinsics-inl.h

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+namespace v8 {
+namespace internal {
+namespace atomics {
+
+template <typename T>
+inline T LoadSeqCst(T* p) {
+  T result;
+  __atomic_load(p, &result, __ATOMIC_SEQ_CST);
+  return result;
+}
+
+
+template <typename T>
+inline void StoreSeqCst(T* p, T value) {
+  __atomic_store_n(p, value, __ATOMIC_SEQ_CST);
+}
+
+
+template <typename T>
+inline T AddSeqCst(T* p, T value) {
+  return __atomic_fetch_add(p, value, __ATOMIC_SEQ_CST);
+}
+
+
+template <typename T>
+inline T SubSeqCst(T* p, T value) {
+  return __atomic_fetch_sub(p, value, __ATOMIC_SEQ_CST);
+}
+
+
+template <typename T>
+inline T AndSeqCst(T* p, T value) {
+  return __atomic_fetch_and(p, value, __ATOMIC_SEQ_CST);
+}
+
+
+template <typename T>
+inline T OrSeqCst(T* p, T value) {
+  return __atomic_fetch_or(p, value, __ATOMIC_SEQ_CST);
+}
+
+
+template <typename T>
+inline T XorSeqCst(T* p, T value) {
+  return __atomic_fetch_xor(p, value, __ATOMIC_SEQ_CST);
+}
+
+
+template <typename T>
+inline T ExchangeSeqCst(T* p, T value) {
+  return __atomic_exchange_n(p, value, __ATOMIC_SEQ_CST);
+}
+
+
+template <typename T>
+inline T CompareExchangeSeqCst(T* p, T oldval, T newval) {
+  (void)__atomic_compare_exchange_n(p, &oldval, newval, 0, __ATOMIC_SEQ_CST,
+                                    __ATOMIC_SEQ_CST);
+  return oldval;
+}
+
+}  // namespace atomics
+}  // namespace internal
+}  // namespace v8