MIPS: Fix memory barriers for atomic operations.

Add barriers using MIPS 'sync' instructions as needed for SMP
systems.

BUG=246947
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/15981017

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15062 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/atomicops_internals_mips_gcc.h

@@ -30,8 +30,6 @@
 #ifndef V8_ATOMICOPS_INTERNALS_MIPS_GCC_H_
 #define V8_ATOMICOPS_INTERNALS_MIPS_GCC_H_
 
-#define ATOMICOPS_COMPILER_BARRIER() __asm__ __volatile__("" : : : "memory")
-
 namespace v8 {
 namespace internal {
 
@@ -111,9 +109,9 @@ inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr,
 
 inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr,
                                         Atomic32 increment) {
-  ATOMICOPS_COMPILER_BARRIER();
+  MemoryBarrier();
   Atomic32 res = NoBarrier_AtomicIncrement(ptr, increment);
-  ATOMICOPS_COMPILER_BARRIER();
+  MemoryBarrier();
   return res;
 }
 
@@ -126,19 +124,16 @@ inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr,
 inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr,
                                        Atomic32 old_value,
                                        Atomic32 new_value) {
-  ATOMICOPS_COMPILER_BARRIER();
   Atomic32 res = NoBarrier_CompareAndSwap(ptr, old_value, new_value);
-  ATOMICOPS_COMPILER_BARRIER();
+  MemoryBarrier();
   return res;
 }
 
 inline Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
                                        Atomic32 old_value,
                                        Atomic32 new_value) {
-  ATOMICOPS_COMPILER_BARRIER();
-  Atomic32 res = NoBarrier_CompareAndSwap(ptr, old_value, new_value);
-  ATOMICOPS_COMPILER_BARRIER();
-  return res;
+  MemoryBarrier();
+  return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
 }
 
 inline void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value) {
@@ -176,6 +171,4 @@ inline Atomic32 Release_Load(volatile const Atomic32* ptr) {
 
 } }  // namespace v8::internal
 
-#undef ATOMICOPS_COMPILER_BARRIER
-
 #endif  // V8_ATOMICOPS_INTERNALS_MIPS_GCC_H_