[heap] Rework and improve object stats tracing

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/heap/heap.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/ast/scopeinfo.h"
 #include "src/base/bits.h"
@@ skipping 123 matching lines @@
       sweeping_time_(0.0),
       last_idle_notification_time_(0.0),
       last_gc_time_(0.0),
       scavenge_collector_(nullptr),
       mark_compact_collector_(nullptr),
       memory_allocator_(nullptr),
       store_buffer_(this),
       incremental_marking_(nullptr),
       gc_idle_time_handler_(nullptr),
       memory_reducer_(nullptr),
-      object_stats_(nullptr),
+      live_object_stats_(nullptr),
+      dead_object_stats_(nullptr),
       scavenge_job_(nullptr),
       idle_scavenge_observer_(nullptr),
       full_codegen_bytes_generated_(0),
       crankshaft_codegen_bytes_generated_(0),
       new_space_allocation_counter_(0),
       old_generation_allocation_counter_(0),
       old_generation_size_at_last_gc_(0),
       gcs_since_last_deopt_(0),
       global_pretenuring_feedback_(nullptr),
       ring_buffer_full_(false),
@@ skipping 5165 matching lines @@
   tracer_ = new GCTracer(this);
 
   scavenge_collector_ = new Scavenger(this);
 
   mark_compact_collector_ = new MarkCompactCollector(this);
 
   gc_idle_time_handler_ = new GCIdleTimeHandler();
 
   memory_reducer_ = new MemoryReducer(this);
 
-  object_stats_ = new ObjectStats(this);
-  object_stats_->ClearObjectStats(true);
+  if (FLAG_track_gc_object_stats) {
+    live_object_stats_ = new ObjectStats(this);
+    dead_object_stats_ = new ObjectStats(this);
+  }
 
   scavenge_job_ = new ScavengeJob();
 
   LOG(isolate_, IntPtrTEvent("heap-capacity", Capacity()));
   LOG(isolate_, IntPtrTEvent("heap-available", Available()));
 
   store_buffer()->SetUp();
 
   mark_compact_collector()->SetUp();
 
@@ skipping 137 matching lines @@
 
   delete gc_idle_time_handler_;
   gc_idle_time_handler_ = nullptr;
 
   if (memory_reducer_ != nullptr) {
     memory_reducer_->TearDown();
     delete memory_reducer_;
     memory_reducer_ = nullptr;
   }
 
-  delete object_stats_;
-  object_stats_ = nullptr;
+  if (live_object_stats_ != nullptr) {
+    delete live_object_stats_;
+    live_object_stats_ = nullptr;
+  }
+
+  if (dead_object_stats_ != nullptr) {
+    delete dead_object_stats_;
+    dead_object_stats_ = nullptr;
+  }
 
   delete scavenge_job_;
   scavenge_job_ = nullptr;
 
   isolate_->global_handles()->TearDown();
 
   external_string_table_.TearDown();
 
   delete tracer_;
   tracer_ = nullptr;
@@ skipping 870 matching lines @@
   }
 }
 
 
 size_t Heap::NumberOfTrackedHeapObjectTypes() {
   return ObjectStats::OBJECT_STATS_COUNT;
 }
 
 
 size_t Heap::ObjectCountAtLastGC(size_t index) {
-  if (index >= ObjectStats::OBJECT_STATS_COUNT) return 0;
-  return object_stats_->object_count_last_gc(index);
+  if (live_object_stats_ == nullptr || index >= ObjectStats::OBJECT_STATS_COUNT)
+    return 0;
+  return live_object_stats_->object_count_last_gc(index);
 }
 
 
 size_t Heap::ObjectSizeAtLastGC(size_t index) {
-  if (index >= ObjectStats::OBJECT_STATS_COUNT) return 0;
-  return object_stats_->object_size_last_gc(index);
+  if (live_object_stats_ == nullptr || index >= ObjectStats::OBJECT_STATS_COUNT)
+    return 0;
+  return live_object_stats_->object_size_last_gc(index);
 }
 
 
 bool Heap::GetObjectTypeName(size_t index, const char** object_type,
                              const char** object_sub_type) {
   if (index >= ObjectStats::OBJECT_STATS_COUNT) return false;
 
   switch (static_cast<int>(index)) {
 #define COMPARE_AND_RETURN_NAME(name) \
   case name:                          \
@@ skipping 29 matching lines @@
 }
 
 
 // static
 int Heap::GetStaticVisitorIdForMap(Map* map) {
   return StaticVisitorBase::GetVisitorId(map);
 }
 
 }  // namespace internal
 }  // namespace v8