Increase bytecode_age with relaxed operation

Release operation uses more expensive operations on some architectures.

Change-Id: Iab84d92c84c791d429b6635641daadb2d608f791
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2276039Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68622}

src/base/atomicops.h

@@ -65,6 +65,8 @@ using AtomicWord = intptr_t;
 // I.e. replace |*ptr| with |new_value| if |*ptr| used to be |old_value|.
 // Always return the value of |*ptr| before the operation.
 // Acquire, Relaxed, Release correspond to standard C++ memory orders.
+Atomic8 Relaxed_CompareAndSwap(volatile Atomic8* ptr, Atomic8 old_value,
+                               Atomic8 new_value);
 Atomic16 Relaxed_CompareAndSwap(volatile Atomic16* ptr, Atomic16 old_value,
                                 Atomic16 new_value);
 Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr, Atomic32 old_value,

src/base/atomicops_internals_portable.h

@@ -50,6 +50,14 @@ inline void SeqCst_MemoryFence() {
 #endif
 }
 
+inline Atomic8 Relaxed_CompareAndSwap(volatile Atomic8* ptr, Atomic8 old_value,
+                                      Atomic8 new_value) {
+  bool result = __atomic_compare_exchange_n(ptr, &old_value, new_value, false,
+                                            __ATOMIC_RELAXED, __ATOMIC_RELAXED);
+  USE(result);  // Make gcc compiler happy.
+  return old_value;
+}
+
 inline Atomic16 Relaxed_CompareAndSwap(volatile Atomic16* ptr,
                                        Atomic16 old_value, Atomic16 new_value) {
   __atomic_compare_exchange_n(ptr, &old_value, new_value, false,

src/base/atomicops_internals_std.h

@@ -28,6 +28,14 @@ inline void SeqCst_MemoryFence() {
   std::atomic_thread_fence(std::memory_order_seq_cst);
 }
 
+inline Atomic8 Relaxed_CompareAndSwap(volatile Atomic8* ptr, Atomic8 old_value,
+                                      Atomic8 new_value) {
+  std::atomic_compare_exchange_strong_explicit(
+      helper::to_std_atomic(ptr), &old_value, new_value,
+      std::memory_order_relaxed, std::memory_order_relaxed);
+  return old_value;
+}
+
 inline Atomic16 Relaxed_CompareAndSwap(volatile Atomic16* ptr,
                                        Atomic16 old_value, Atomic16 new_value) {
   std::atomic_compare_exchange_strong_explicit(

src/objects/code.cc

@@ -841,8 +841,8 @@ void BytecodeArray::MakeOlder() {
   DCHECK_LE(RoundDown(age_addr, kTaggedSize) + kTaggedSize, address() + Size());
   Age age = bytecode_age();
   if (age < kLastBytecodeAge) {
-    base::AsAtomic8::Release_CompareAndSwap(reinterpret_cast<byte*>(age_addr),
-                                            age, age + 1);
+    base::AsAtomic8::Relaxed_CompareAndSwap(
+        reinterpret_cast<base::Atomic8*>(age_addr), age, age + 1);
   }
 
   DCHECK_GE(bytecode_age(), kFirstBytecodeAge);