[heap] pause observers during mark-compact

Inline allocations performed during mark compact aren't real allocations. They
should not trigger inline-allocation-observer notifications.

R=hpayer@chromium.org, ulan@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1465223009

Cr-Commit-Position: refs/heads/master@{#32566}

src/heap/heap.cc

@@ -1380,6 +1380,8 @@ void Heap::CallGCEpilogueCallbacks(GCType gc_type,
 
 
 void Heap::MarkCompact() {
+  PauseInlineAllocationObserversScope pause_observers(new_space());
+
   gc_state_ = MARK_COMPACT;
   LOG(isolate_, ResourceEvent("markcompact", "begin"));
 
@@ -1584,7 +1586,7 @@ void Heap::Scavenge() {
 
   // Bump-pointer allocations done during scavenge are not real allocations.
   // Pause the inline allocation steps.
-  new_space()->PauseInlineAllocationObservers();
+  PauseInlineAllocationObserversScope pause_observers(new_space());
 
 #ifdef VERIFY_HEAP
   if (FLAG_verify_heap) VerifyNonPointerSpacePointers(this);
@@ -1715,8 +1717,6 @@ void Heap::Scavenge() {
   // Set age mark.
   new_space_.set_age_mark(new_space_.top());
 
-  new_space()->ResumeInlineAllocationObservers();
-
   array_buffer_tracker()->FreeDead(true);
 
   // Update how much has survived scavenge.

src/heap/spaces.cc

@@ -1604,10 +1604,11 @@ bool NewSpace::EnsureAllocation(int size_in_bytes,
 
 
 void NewSpace::StartNextInlineAllocationStep() {
-  DCHECK(!inline_allocation_observers_paused_);
-  top_on_previous_step_ =
-      inline_allocation_observers_.length() ? allocation_info_.top() : 0;
-  UpdateInlineAllocationLimit(0);
+  if (!inline_allocation_observers_paused_) {
+    top_on_previous_step_ =
+        inline_allocation_observers_.length() ? allocation_info_.top() : 0;
+    UpdateInlineAllocationLimit(0);
+  }
 }
 
 

src/heap/spaces.h

@@ -2755,9 +2755,6 @@ class NewSpace : public Space {
   // Removes a previously installed observer.
   void RemoveInlineAllocationObserver(InlineAllocationObserver* observer);
 
-  void PauseInlineAllocationObservers();
-  void ResumeInlineAllocationObservers();
-
   void DisableInlineAllocationSteps() {
     top_on_previous_step_ = 0;
     UpdateInlineAllocationLimit(0);
@@ -2879,10 +2876,28 @@ class NewSpace : public Space {
                             size_t size);
   intptr_t GetNextInlineAllocationStepSize();
   void StartNextInlineAllocationStep();
+  void PauseInlineAllocationObservers();
+  void ResumeInlineAllocationObservers();
 
+  friend class PauseInlineAllocationObserversScope;
   friend class SemiSpaceIterator;
 };
 
+class PauseInlineAllocationObserversScope {
+ public:
+  explicit PauseInlineAllocationObserversScope(NewSpace* new_space)
+      : new_space_(new_space) {
+    new_space_->PauseInlineAllocationObservers();
+  }
+  ~PauseInlineAllocationObserversScope() {
+    new_space_->ResumeInlineAllocationObservers();
+  }
+
+ private:
+  NewSpace* new_space_;
+  DISALLOW_COPY_AND_ASSIGN(PauseInlineAllocationObserversScope);
+};
+
 // -----------------------------------------------------------------------------
 // Compaction space that is used temporarily during compaction.
 

test/cctest/test-spaces.cc

@@ -872,14 +872,15 @@ UNINITIALIZED_TEST(InlineAllocationObserver) {
     CHECK_EQ(observer1.count(), 20);  // no more notifications.
     CHECK_EQ(observer2.count(), 3);   // this one is still active.
 
-    // Ensure that Pause/ResumeInlineAllocationObservers work correctly.
+    // Ensure that PauseInlineAllocationObserversScope work correctly.
     AllocateUnaligned(new_space, 48);
     CHECK_EQ(observer2.count(), 3);
-    new_space->PauseInlineAllocationObservers();
-    CHECK_EQ(observer2.count(), 3);
-    AllocateUnaligned(new_space, 384);
-    CHECK_EQ(observer2.count(), 3);
-    new_space->ResumeInlineAllocationObservers();
+    {
+      PauseInlineAllocationObserversScope pause_observers(new_space);
+      CHECK_EQ(observer2.count(), 3);
+      AllocateUnaligned(new_space, 384);
+      CHECK_EQ(observer2.count(), 3);
+    }
     CHECK_EQ(observer2.count(), 3);
     // Coupled with the 48 bytes allocated before the pause, another 48 bytes
     // allocated here should trigger a notification.