Add a flag to over approximate the weak closure during GC

src/heap/heap.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/v8.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/bits.h"
 #include "src/base/once.h"
@@ skipping 716 matching lines @@
 #ifdef DEBUG
   ReportStatisticsAfterGC();
 #endif  // DEBUG
 
   // Remember the last top pointer so that we can later find out
   // whether we allocated in new space since the last GC.
   new_space_top_after_last_gc_ = new_space()->top();
 }
 
 
+void Heap::HandleGCRequest() {
+  if (incremental_marking()->request_type() ==
+      IncrementalMarking::COMPLETE_MARKING) {
+    CollectAllGarbage(Heap::kNoGCFlags, "GC interrupt");
+    return;
+  }
+  DCHECK(FLAG_overapproximate_weak_closure);
+  DCHECK(!incremental_marking()->weak_closure_was_overapproximated());
+  OverApproximateWeakClosure("GC interrupt");
+}
+
+
+void Heap::OverApproximateWeakClosure(const char* gc_reason) {
+  if (FLAG_trace_incremental_marking) {
+    PrintF("[IncrementalMarking] Overapproximate weak closure (%s).\n",
+           gc_reason);
+  }
+  {
+    GCCallbacksScope scope(this);
+    if (scope.CheckReenter()) {
+      AllowHeapAllocation allow_allocation;
+      GCTracer::Scope scope(tracer(), GCTracer::Scope::EXTERNAL);
+      VMState<EXTERNAL> state(isolate_);
+      HandleScope handle_scope(isolate_);
+      CallGCPrologueCallbacks(kGCTypeMarkSweepCompact, kNoGCCallbackFlags);
+    }
+  }
+  mark_compact_collector()->OverApproximateWeakClosure();
+  incremental_marking()->set_should_hurry(false);
+  incremental_marking()->set_weak_closure_was_overapproximated(true);
+  {
+    GCCallbacksScope scope(this);
+    if (scope.CheckReenter()) {
+      AllowHeapAllocation allow_allocation;
+      GCTracer::Scope scope(tracer(), GCTracer::Scope::EXTERNAL);
+      VMState<EXTERNAL> state(isolate_);
+      HandleScope handle_scope(isolate_);
+      CallGCEpilogueCallbacks(kGCTypeMarkSweepCompact, kNoGCCallbackFlags);
+    }
+  }
+}
+
+
 void Heap::CollectAllGarbage(int flags, const char* gc_reason,
                              const v8::GCCallbackFlags gc_callback_flags) {
   // Since we are ignoring the return value, the exact choice of space does
   // not matter, so long as we do not specify NEW_SPACE, which would not
   // cause a full GC.
   mark_compact_collector_.SetFlags(flags);
   CollectGarbage(OLD_POINTER_SPACE, gc_reason, gc_callback_flags);
   mark_compact_collector_.SetFlags(kNoGCFlags);
 }
 
@@ skipping 5742 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   CODE_AGE_LIST_COMPLETE(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   MemCopy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   MemCopy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 }
 }  // namespace v8::internal