[heap] Turn on black allocation during marking finalization to avoid floating garbage.

src/heap/incremental-marking.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/heap/incremental-marking.h"
 
 #include "src/code-stubs.h"
 #include "src/compilation-cache.h"
 #include "src/conversions.h"
 #include "src/heap/gc-idle-time-handler.h"
@@ skipping 539 matching lines @@
   }
 #endif
 
   heap_->CompletelyClearInstanceofCache();
   heap_->isolate()->compilation_cache()->MarkCompactPrologue();
 
   // Mark strong roots grey.
   IncrementalMarkingRootMarkingVisitor visitor(this);
   heap_->IterateStrongRoots(&visitor, VISIT_ONLY_STRONG);
 
-  if (FLAG_black_allocation && !heap()->ShouldReduceMemory()) {
-    StartBlackAllocation();
-  }
-
   // Ready to start incremental marking.
   if (FLAG_trace_incremental_marking) {
     PrintF("[IncrementalMarking] Running\n");
   }
 }
 
 void IncrementalMarking::StartBlackAllocation() {
   DCHECK(FLAG_black_allocation);
   DCHECK(IsMarking());
   black_allocation_ = true;
@@ skipping 180 matching lines @@
         static_cast<int>(delta), incremental_marking_finalization_rounds_,
         marking_progress);
   }
 
   ++incremental_marking_finalization_rounds_;
   if ((incremental_marking_finalization_rounds_ >=
        FLAG_max_incremental_marking_finalization_rounds) ||
       (marking_progress <
        FLAG_min_progress_during_incremental_marking_finalization)) {
     finalize_marking_completed_ = true;
+  }
 
-    // If black allocation was not enabled earlier, start black allocation
-    // here.
-    if (FLAG_black_allocation && !black_allocation_) {
-      StartBlackAllocation();
-    }
+  if (FLAG_black_allocation && !heap()->ShouldReduceMemory() &&
+      !black_allocation_) {
+    // TODO(hpayer): Move to an earlier point as soon as we make faster marking
+    // progress.
+    StartBlackAllocation();
   }
 }
 
 
 void IncrementalMarking::UpdateMarkingDequeAfterScavenge() {
   if (!IsMarking()) return;
 
   MarkingDeque* marking_deque =
       heap_->mark_compact_collector()->marking_deque();
   int current = marking_deque->bottom();
@@ skipping 463 matching lines @@
 void IncrementalMarking::IncrementIdleMarkingDelayCounter() {
   idle_marking_delay_counter_++;
 }
 
 
 void IncrementalMarking::ClearIdleMarkingDelayCounter() {
   idle_marking_delay_counter_ = 0;
 }
 }  // namespace internal
 }  // namespace v8