[heap] Invoke incremental marking step before allocation.

This ensures that the newly allocated object immediatly precedes the
linear allocation area, which is needed for allocation folding.

For more info see:
https://bugs.chromium.org/p/chromium/issues/detail?id=659165#c13

BUG=chromium:659165

Review-Url: https://codereview.chromium.org/2464393002
Cr-Commit-Position: refs/heads/master@{#40704}

src/heap/incremental-marking.cc

@@ -32,9 +32,7 @@ IncrementalMarking::IncrementalMarking(Heap* heap)
       was_activated_(false),
       black_allocation_(false),
       finalize_marking_completed_(false),
-      request_type_(NONE),
-      new_generation_observer_(*this, kAllocatedThreshold),
-      old_generation_observer_(*this, kAllocatedThreshold) {}
+      request_type_(NONE) {}
 
 bool IncrementalMarking::BaseRecordWrite(HeapObject* obj, Object* value) {
   HeapObject* value_heap_obj = HeapObject::cast(value);
@@ -489,16 +487,6 @@ void IncrementalMarking::Start(GarbageCollectionReason gc_reason) {
     state_ = SWEEPING;
   }
 
-  SpaceIterator it(heap_);
-  while (it.has_next()) {
-    Space* space = it.next();
-    if (space == heap_->new_space()) {
-      space->AddAllocationObserver(&new_generation_observer_);
-    } else {
-      space->AddAllocationObserver(&old_generation_observer_);
-    }
-  }
-
   incremental_marking_job()->Start(heap_);
 }
 
@@ -957,16 +945,6 @@ void IncrementalMarking::Stop() {
         Max(0, old_generation_size_mb - old_generation_limit_mb));
   }
 
-  SpaceIterator it(heap_);
-  while (it.has_next()) {
-    Space* space = it.next();
-    if (space == heap_->new_space()) {
-      space->RemoveAllocationObserver(&new_generation_observer_);
-    } else {
-      space->RemoveAllocationObserver(&old_generation_observer_);
-    }
-  }
-
   IncrementalMarking::set_should_hurry(false);
   if (IsMarking()) {
     PatchIncrementalMarkingRecordWriteStubs(heap_,
@@ -1085,30 +1063,33 @@ void IncrementalMarking::AdvanceIncrementalMarkingOnAllocation() {
     return;
   }
 
-  size_t bytes_to_process =
-      StepSizeToKeepUpWithAllocations() + StepSizeToMakeProgress();
-
-  if (bytes_to_process >= IncrementalMarking::kAllocatedThreshold) {
-    // The first step after Scavenge will see many allocated bytes.
-    // Cap the step size to distribute the marking work more uniformly.
-    size_t max_step_size = GCIdleTimeHandler::EstimateMarkingStepSize(
-        kMaxStepSizeInMs,
-        heap()->tracer()->IncrementalMarkingSpeedInBytesPerMillisecond());
-    bytes_to_process = Min(bytes_to_process, max_step_size);
-
-    size_t bytes_processed = 0;
-    if (bytes_marked_ahead_of_schedule_ >= bytes_to_process) {
-      // Steps performed in tasks have put us ahead of schedule.
-      // We skip processing of marking dequeue here and thus
-      // shift marking time from inside V8 to standalone tasks.
-      bytes_marked_ahead_of_schedule_ -= bytes_to_process;
-      bytes_processed = bytes_to_process;
-    } else {
-      bytes_processed = Step(bytes_to_process, GC_VIA_STACK_GUARD,
-                             FORCE_COMPLETION, StepOrigin::kV8);
-    }
-    bytes_allocated_ -= Min(bytes_allocated_, bytes_processed);
+  size_t bytes_to_process = StepSizeToKeepUpWithAllocations();
+
+  if (bytes_to_process < IncrementalMarking::kAllocatedThreshold) {
+    return;
+  }
+
+  bytes_to_process += StepSizeToMakeProgress();
+
+  // The first step after Scavenge will see many allocated bytes.
+  // Cap the step size to distribute the marking work more uniformly.
+  size_t max_step_size = GCIdleTimeHandler::EstimateMarkingStepSize(
+      kMaxStepSizeInMs,
+      heap()->tracer()->IncrementalMarkingSpeedInBytesPerMillisecond());
+  bytes_to_process = Min(bytes_to_process, max_step_size);
+
+  size_t bytes_processed = 0;
+  if (bytes_marked_ahead_of_schedule_ >= bytes_to_process) {
+    // Steps performed in tasks have put us ahead of schedule.
+    // We skip processing of marking dequeue here and thus
+    // shift marking time from inside V8 to standalone tasks.
+    bytes_marked_ahead_of_schedule_ -= bytes_to_process;
+    bytes_processed = bytes_to_process;
+  } else {
+    bytes_processed = Step(bytes_to_process, GC_VIA_STACK_GUARD,
+                           FORCE_COMPLETION, StepOrigin::kV8);
   }
+  bytes_allocated_ -= Min(bytes_allocated_, bytes_processed);
 }
 
 size_t IncrementalMarking::Step(size_t bytes_to_process,

src/heap/incremental-marking.h

@@ -99,6 +99,7 @@ class IncrementalMarking {
                                    CompletionAction completion_action,
                                    ForceCompletionAction force_completion,
                                    StepOrigin step_origin);
+  void AdvanceIncrementalMarkingOnAllocation();
 
   // It's hard to know how much work the incremental marker should do to make
   // progress in the face of the mutator creating new work for it.  We start
@@ -218,20 +219,6 @@ class IncrementalMarking {
   void AbortBlackAllocation();
 
  private:
-  class Observer : public AllocationObserver {
-   public:
-    Observer(IncrementalMarking& incremental_marking, intptr_t step_size)
-        : AllocationObserver(step_size),
-          incremental_marking_(incremental_marking) {}
-
-    void Step(int bytes_allocated, Address, size_t) override {
-      incremental_marking_.AdvanceIncrementalMarkingOnAllocation();
-    }
-
-   private:
-    IncrementalMarking& incremental_marking_;
-  };
-
   int64_t SpaceLeftInOldSpace();
 
   void StartMarking();
@@ -269,8 +256,6 @@ class IncrementalMarking {
 
   void IncrementIdleMarkingDelayCounter();
 
-  void AdvanceIncrementalMarkingOnAllocation();
-
   size_t StepSizeToKeepUpWithAllocations();
   size_t StepSizeToMakeProgress();
 
@@ -297,8 +282,6 @@ class IncrementalMarking {
   GCRequestType request_type_;
 
   IncrementalMarkingJob incremental_marking_job_;
-  Observer new_generation_observer_;
-  Observer old_generation_observer_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(IncrementalMarking);
 };

src/heap/spaces.cc

@@ -2582,6 +2582,15 @@ HeapObject* FreeList::Allocate(size_t size_in_bytes) {
 
   owner_->heap()->StartIncrementalMarkingIfAllocationLimitIsReached(
       Heap::kNoGCFlags, kNoGCCallbackFlags);
+  // We cannot place incremental marking step in an AllocationObserver because
+  // 1) incremental marking step can change linear allocation area.
+  // 2) allocation observers are called after allocation.
+  // 3) allocation folding assumes that the newly allocated object immediately
+  //    precedes the linear allocation area.
+  // See crbug.com/659165.
+  owner_->heap()
+      ->incremental_marking()
+      ->AdvanceIncrementalMarkingOnAllocation();
 
   size_t new_node_size = 0;
   FreeSpace* new_node = FindNodeFor(size_in_bytes, &new_node_size);
@@ -3011,6 +3020,8 @@ AllocationResult LargeObjectSpace::AllocateRaw(int object_size,
 
   heap()->StartIncrementalMarkingIfAllocationLimitIsReached(Heap::kNoGCFlags,
                                                             kNoGCCallbackFlags);
+  heap()->incremental_marking()->AdvanceIncrementalMarkingOnAllocation();
+
   AllocationStep(object->address(), object_size);
 
   if (heap()->incremental_marking()->black_allocation()) {