Use std::atomic in optimizing compiler dispatcher.

Change-Id: Ia1f47083689abb7d37c91098465a107a71f4dbea
Reviewed-on: https://chromium-review.googlesource.com/c/1225757
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57375}

src/compiler-dispatcher/optimizing-compile-dispatcher.cc

@@ -112,7 +112,7 @@ OptimizedCompilationJob* OptimizingCompileDispatcher::NextInput(
   input_queue_shift_ = InputQueueIndex(1);
   input_queue_length_--;
   if (check_if_flushing) {
-    if (static_cast<ModeFlag>(base::Acquire_Load(&mode_)) == FLUSH) {
+    if (mode_ == FLUSH) {
       AllowHandleDereference allow_handle_dereference;
       DisposeCompilationJob(job, true);
       return nullptr;
@@ -167,12 +167,12 @@ void OptimizingCompileDispatcher::Flush(BlockingBehavior blocking_behavior) {
     }
     return;
   }
-  base::Release_Store(&mode_, static_cast<base::AtomicWord>(FLUSH));
+  mode_ = FLUSH;
   if (FLAG_block_concurrent_recompilation) Unblock();
   {
     base::MutexGuard lock_guard(&ref_count_mutex_);
     while (ref_count_ > 0) ref_count_zero_.Wait(&ref_count_mutex_);
-    base::Release_Store(&mode_, static_cast<base::AtomicWord>(COMPILE));
+    mode_ = COMPILE;
   }
   FlushOutputQueue(true);
   if (FLAG_trace_concurrent_recompilation) {
@@ -181,12 +181,12 @@ void OptimizingCompileDispatcher::Flush(BlockingBehavior blocking_behavior) {
 }
 
 void OptimizingCompileDispatcher::Stop() {
-  base::Release_Store(&mode_, static_cast<base::AtomicWord>(FLUSH));
+  mode_ = FLUSH;
   if (FLAG_block_concurrent_recompilation) Unblock();
   {
     base::MutexGuard lock_guard(&ref_count_mutex_);
     while (ref_count_ > 0) ref_count_zero_.Wait(&ref_count_mutex_);
-    base::Release_Store(&mode_, static_cast<base::AtomicWord>(COMPILE));
+    mode_ = COMPILE;
   }
 
   if (recompilation_delay_ != 0) {

src/compiler-dispatcher/optimizing-compile-dispatcher.h

@@ -5,10 +5,10 @@
 #ifndef V8_COMPILER_DISPATCHER_OPTIMIZING_COMPILE_DISPATCHER_H_
 #define V8_COMPILER_DISPATCHER_OPTIMIZING_COMPILE_DISPATCHER_H_
 
+#include <atomic>
 #include <queue>
 
 #include "src/allocation.h"
-#include "src/base/atomicops.h"
 #include "src/base/platform/condition-variable.h"
 #include "src/base/platform/mutex.h"
 #include "src/base/platform/platform.h"
@@ -28,10 +28,10 @@ class V8_EXPORT_PRIVATE OptimizingCompileDispatcher {
         input_queue_capacity_(FLAG_concurrent_recompilation_queue_length),
         input_queue_length_(0),
         input_queue_shift_(0),
+        mode_(COMPILE),
         blocked_jobs_(0),
         ref_count_(0),
         recompilation_delay_(FLAG_concurrent_recompilation_delay) {
-    base::Relaxed_Store(&mode_, static_cast<base::AtomicWord>(COMPILE));
     input_queue_ = NewArray<OptimizedCompilationJob*>(input_queue_capacity_);
   }
 
@@ -82,7 +82,7 @@ class V8_EXPORT_PRIVATE OptimizingCompileDispatcher {
   // different threads.
   base::Mutex output_queue_mutex_;
 
-  volatile base::AtomicWord mode_;
+  std::atomic<ModeFlag> mode_;
 
   int blocked_jobs_;