Introduced Atomic8 and added no-barrier Atomic8 accessors.

src/atomicops_internals_x86_gcc.h

 // Copyright 2010 the V8 project authors. 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
@@ skipping 89 matching lines @@
   }
   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 Atomic8* ptr, Atomic8 value) {
+  *ptr = 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");
@@ skipping 25 matching lines @@
   }
 }
 #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 Atomic8 NoBarrier_Load(volatile const Atomic8* ptr) {
+  return *ptr;
+}
+
 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;
 }
@@ skipping 113 matching lines @@
   return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
 }
 
 #endif  // defined(__x86_64__)
 
 } }  // namespace v8::internal
 
 #undef ATOMICOPS_COMPILER_BARRIER
 
 #endif  // V8_ATOMICOPS_INTERNALS_X86_GCC_H_