From 4d6c4a3e22dadaab89a1fded92a0423b1ca9f035 Mon Sep 17 00:00:00 2001
From: mlippautz <mlippautz@chromium.org>
Date: Tue, 15 Sep 2015 07:58:44 -0700
Subject: [PATCH] Add barriers to atomic utils.

Loads get an acquire, store/cas a release. Increment gets a full barrier.

R=hpayer@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1343883004

Cr-Commit-Position: refs/heads/master@{#30751}
---
 src/atomic-utils.h                      | 22 ++++++++++------------
 test/unittests/atomic-utils-unittest.cc |  4 ++--
 2 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/src/atomic-utils.h b/src/atomic-utils.h
index 8e11833..2aa78f8 100644
--- a/src/atomic-utils.h
+++ b/src/atomic-utils.h
@@ -20,14 +20,14 @@ class AtomicNumber {
   explicit AtomicNumber(T initial) : value_(initial) {}
 
   V8_INLINE void Increment(T increment) {
-    base::NoBarrier_AtomicIncrement(&value_,
-                                    static_cast<base::AtomicWord>(increment));
+    base::Barrier_AtomicIncrement(&value_,
+                                  static_cast<base::AtomicWord>(increment));
   }
 
-  V8_INLINE T Value() { return static_cast<T>(base::NoBarrier_Load(&value_)); }
+  V8_INLINE T Value() { return static_cast<T>(base::Acquire_Load(&value_)); }
 
   V8_INLINE void SetValue(T new_value) {
-    base::NoBarrier_Store(&value_, static_cast<base::AtomicWord>(new_value));
+    base::Release_Store(&value_, static_cast<base::AtomicWord>(new_value));
   }
 
   V8_INLINE T operator=(T value) {
@@ -52,19 +52,18 @@ class AtomicValue {
       : value_(cast_helper<T>::to_storage_type(initial)) {}
 
   V8_INLINE T Value() {
-    return cast_helper<T>::to_return_type(base::NoBarrier_Load(&value_));
+    return cast_helper<T>::to_return_type(base::Acquire_Load(&value_));
   }
 
   V8_INLINE bool TrySetValue(T old_value, T new_value) {
-    return base::NoBarrier_CompareAndSwap(
+    return base::Release_CompareAndSwap(
                &value_, cast_helper<T>::to_storage_type(old_value),
                cast_helper<T>::to_storage_type(new_value)) ==
            cast_helper<T>::to_storage_type(old_value);
   }
 
-  V8_INLINE T /*old_value*/ SetValue(T new_value) {
-    return cast_helper<T>::to_return_type(base::NoBarrier_AtomicExchange(
-        &value_, cast_helper<T>::to_storage_type(new_value)));
+  V8_INLINE void SetValue(T new_value) {
+    base::Release_Store(&value_, cast_helper<T>::to_storage_type(new_value));
   }
 
  private:
@@ -109,12 +108,11 @@ class AtomicEnumSet {
   bool IsEmpty() const { return ToIntegral() == 0; }
 
   bool Contains(E element) const { return (ToIntegral() & Mask(element)) != 0; }
-
   bool ContainsAnyOf(const AtomicEnumSet& set) const {
     return (ToIntegral() & set.ToIntegral()) != 0;
   }
 
-  void RemoveAll() { base::NoBarrier_Store(&bits_, 0); }
+  void RemoveAll() { base::Release_Store(&bits_, 0); }
 
   bool operator==(const AtomicEnumSet& set) const {
     return ToIntegral() == set.ToIntegral();
@@ -160,7 +158,7 @@ class AtomicEnumSet {
   STATIC_ASSERT(E::kLastValue < (sizeof(base::AtomicWord) * CHAR_BIT));
 
   V8_INLINE base::AtomicWord ToIntegral() const {
-    return base::NoBarrier_Load(&bits_);
+    return base::Acquire_Load(&bits_);
   }
 
   V8_INLINE base::AtomicWord Mask(E element) const {
diff --git a/test/unittests/atomic-utils-unittest.cc b/test/unittests/atomic-utils-unittest.cc
index a0d8a6a..ad33853 100644
--- a/test/unittests/atomic-utils-unittest.cc
+++ b/test/unittests/atomic-utils-unittest.cc
@@ -86,7 +86,7 @@ TEST(AtomicValue, TrySetValue) {
 
 TEST(AtomicValue, SetValue) {
   AtomicValue<TestFlag> a(kB);
-  EXPECT_EQ(kB, a.SetValue(kC));
+  a.SetValue(kC);
   EXPECT_EQ(TestFlag::kC, a.Value());
 }
 
@@ -95,7 +95,7 @@ TEST(AtomicValue, WithVoidStar) {
   AtomicValue<void*> a(nullptr);
   AtomicValue<void*> dummy(nullptr);
   EXPECT_EQ(nullptr, a.Value());
-  EXPECT_EQ(nullptr, a.SetValue(&a));
+  a.SetValue(&a);
   EXPECT_EQ(&a, a.Value());
   EXPECT_FALSE(a.TrySetValue(nullptr, &dummy));
   EXPECT_TRUE(a.TrySetValue(&a, &dummy));
-- 
2.7.4