Switch Isolate to std::atomic

Remove another use of atomicops.

R=mstarzinger@chromium.org

Bug: v8:8834
Change-Id: Ide1aa87f4bb4cdc4346fe7b1bf78b8118592c7ae
Reviewed-on: https://chromium-review.googlesource.com/c/1491603
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59935}

src/isolate.cc

@@ -296,11 +296,15 @@ size_t Isolate::HashIsolateForEmbeddedBlob() {
 
 base::Thread::LocalStorageKey Isolate::isolate_key_;
 base::Thread::LocalStorageKey Isolate::per_isolate_thread_data_key_;
-base::Atomic32 Isolate::isolate_counter_ = 0;
 #if DEBUG
-base::Atomic32 Isolate::isolate_key_created_ = 0;
+std::atomic<bool> Isolate::isolate_key_created_{false};
 #endif
 
+namespace {
+// A global counter for all generated Isolates, might overflow.
+std::atomic<int> isolate_counter{0};
+}  // namespace
+
 Isolate::PerIsolateThreadData*
     Isolate::FindOrAllocatePerThreadDataForThisThread() {
   ThreadId thread_id = ThreadId::Current();
@@ -352,7 +356,9 @@ Isolate::PerIsolateThreadData* Isolate::FindPerThreadDataForThread(
 void Isolate::InitializeOncePerProcess() {
   isolate_key_ = base::Thread::CreateThreadLocalKey();
 #if DEBUG
-  base::Relaxed_Store(&isolate_key_created_, 1);
+  bool expected = false;
+  DCHECK_EQ(true, isolate_key_created_.compare_exchange_strong(
+                      expected, true, std::memory_order_relaxed));
 #endif
   per_isolate_thread_data_key_ = base::Thread::CreateThreadLocalKey();
 }
@@ -2817,7 +2823,7 @@ void Isolate::Delete(Isolate* isolate) {
   // direct pointer. We don't use Enter/Exit here to avoid
   // initializing the thread data.
   PerIsolateThreadData* saved_data = isolate->CurrentPerIsolateThreadData();
-  DCHECK_EQ(base::Relaxed_Load(&isolate_key_created_), 1);
+  DCHECK_EQ(true, isolate_key_created_.load(std::memory_order_relaxed));
   Isolate* saved_isolate = reinterpret_cast<Isolate*>(
       base::Thread::GetThreadLocal(isolate->isolate_key_));
   SetIsolateThreadLocals(isolate, nullptr);
@@ -2846,7 +2852,7 @@ v8::PageAllocator* Isolate::page_allocator() {
 
 Isolate::Isolate(std::unique_ptr<i::IsolateAllocator> isolate_allocator)
     : isolate_allocator_(std::move(isolate_allocator)),
-      id_(base::Relaxed_AtomicIncrement(&isolate_counter_, 1)),
+      id_(isolate_counter.fetch_add(1, std::memory_order_relaxed)),
       stack_guard_(this),
       allocator_(FLAG_trace_zone_stats ? new VerboseAccountingAllocator(
                                              &heap_, 256 * KB, 128 * KB)
@@ -4497,12 +4503,12 @@ double Isolate::LoadStartTimeMs() {
 }
 
 void Isolate::SetRAILMode(RAILMode rail_mode) {
-  RAILMode old_rail_mode = rail_mode_.Value();
+  RAILMode old_rail_mode = rail_mode_.load();
   if (old_rail_mode != PERFORMANCE_LOAD && rail_mode == PERFORMANCE_LOAD) {
     base::MutexGuard guard(&rail_mutex_);
     load_start_time_ms_ = heap()->MonotonicallyIncreasingTimeInMs();
   }
-  rail_mode_.SetValue(rail_mode);
+  rail_mode_.store(rail_mode);
   if (old_rail_mode == PERFORMANCE_LOAD && rail_mode != PERFORMANCE_LOAD) {
     heap()->incremental_marking()->incremental_marking_job()->ScheduleTask(
         heap());

src/isolate.h

@@ -16,7 +16,6 @@
 #include "include/v8-internal.h"
 #include "include/v8.h"
 #include "src/allocation.h"
-#include "src/base/atomicops.h"
 #include "src/base/macros.h"
 #include "src/builtins/builtins.h"
 #include "src/contexts.h"
@@ -499,7 +498,7 @@ class Isolate final : private HiddenFactory {
 
   // Returns the isolate inside which the current thread is running or nullptr.
   V8_INLINE static Isolate* TryGetCurrent() {
-    DCHECK_EQ(base::Relaxed_Load(&isolate_key_created_), 1);
+    DCHECK_EQ(true, isolate_key_created_.load(std::memory_order_relaxed));
     return reinterpret_cast<Isolate*>(
         base::Thread::GetExistingThreadLocal(isolate_key_));
   }
@@ -1248,7 +1247,7 @@ class Isolate final : private HiddenFactory {
   // compile dispatcher's queue.
   void AbortConcurrentOptimization(BlockingBehavior blocking_behavior);
 
-  int id() const { return static_cast<int>(id_); }
+  int id() const { return id_; }
 
   CompilationStatistics* GetTurboStatistics();
   CodeTracer* GetCodeTracer();
@@ -1450,7 +1449,7 @@ class Isolate final : private HiddenFactory {
 
   void SetRAILMode(RAILMode rail_mode);
 
-  RAILMode rail_mode() { return rail_mode_.Value(); }
+  RAILMode rail_mode() { return rail_mode_.load(); }
 
   double LoadStartTimeMs();
 
@@ -1548,11 +1547,8 @@ class Isolate final : private HiddenFactory {
   static base::Thread::LocalStorageKey per_isolate_thread_data_key_;
   static base::Thread::LocalStorageKey isolate_key_;
 
-  // A global counter for all generated Isolates, might overflow.
-  static base::Atomic32 isolate_counter_;
-
-#if DEBUG
-  static base::Atomic32 isolate_key_created_;
+#ifdef DEBUG
+  static std::atomic<bool> isolate_key_created_;
 #endif
 
   void Deinit();
@@ -1599,7 +1595,7 @@ class Isolate final : private HiddenFactory {
   std::unique_ptr<IsolateAllocator> isolate_allocator_;
   Heap heap_;
 
-  base::Atomic32 id_;
+  const int id_;
   EntryStackItem* entry_stack_ = nullptr;
   int stack_trace_nesting_level_ = 0;
   StringStream* incomplete_message_ = nullptr;
@@ -1641,7 +1637,7 @@ class Isolate final : private HiddenFactory {
   DateCache* date_cache_ = nullptr;
   base::RandomNumberGenerator* random_number_generator_ = nullptr;
   base::RandomNumberGenerator* fuzzer_rng_ = nullptr;
-  base::AtomicValue<RAILMode> rail_mode_;
+  std::atomic<RAILMode> rail_mode_;
   v8::Isolate::AtomicsWaitCallback atomics_wait_callback_ = nullptr;
   void* atomics_wait_callback_data_ = nullptr;
   PromiseHook promise_hook_ = nullptr;