Trace how long it takes to compute the weak closure during mark-compact

src/heap/gc-tracer.cc

 // Copyright 2014 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/heap/gc-tracer.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 321 matching lines @@
   PrintF("root_new=%.1f ",
          current_.scopes[Scope::MC_UPDATE_ROOT_TO_NEW_POINTERS]);
   PrintF("old_new=%.1f ",
          current_.scopes[Scope::MC_UPDATE_OLD_TO_NEW_POINTERS]);
   PrintF("compaction_ptrs=%.1f ",
          current_.scopes[Scope::MC_UPDATE_POINTERS_TO_EVACUATED]);
   PrintF("intracompaction_ptrs=%.1f ",
          current_.scopes[Scope::MC_UPDATE_POINTERS_BETWEEN_EVACUATED]);
   PrintF("misc_compaction=%.1f ",
          current_.scopes[Scope::MC_UPDATE_MISC_POINTERS]);
+  PrintF("weak_closure=%.1f ", current_.scopes[Scope::MC_WEAKCLOSURE]);
   PrintF("weakcollection_process=%.1f ",
          current_.scopes[Scope::MC_WEAKCOLLECTION_PROCESS]);
   PrintF("weakcollection_clear=%.1f ",
          current_.scopes[Scope::MC_WEAKCOLLECTION_CLEAR]);
   PrintF("weakcollection_abort=%.1f ",
          current_.scopes[Scope::MC_WEAKCOLLECTION_ABORT]);
 
   PrintF("total_size_before=%" V8_PTR_PREFIX "d ", current_.start_object_size);
   PrintF("total_size_after=%" V8_PTR_PREFIX "d ", current_.end_object_size);
   PrintF("holes_size_before=%" V8_PTR_PREFIX "d ", current_.start_holes_size);
@@ skipping 198 matching lines @@
       context_disposal_events_.begin();
   while (iter != context_disposal_events_.end()) {
     end = iter->time_;
     ++iter;
   }
 
   return (begin - end) / context_disposal_events_.size();
 }
 }
 }  // namespace v8::internal