[heap] Add store and slots buffer clearing timers to --trace-gc-nvp.

Review URL: https://codereview.chromium.org/1412123006

Cr-Commit-Position: refs/heads/master@{#31515}

src/heap/gc-tracer.cc

@@ -485,6 +485,8 @@ void GCTracer::PrintNVP() const {
                    "mark_weakrefs=%.1f "
                    "mark_globalhandles=%.1f "
                    "mark_codeflush=%.1f "
+                   "store_buffer_clear=%.1f "
+                   "slots_buffer_clear=%.1f "
                    "sweep=%.2f "
                    "sweepns=%.2f "
                    "sweepos=%.2f "
@@ -548,6 +550,8 @@ void GCTracer::PrintNVP() const {
                    current_.scopes[Scope::MC_MARK_WEAK_REFERENCES],
                    current_.scopes[Scope::MC_MARK_GLOBAL_HANDLES],
                    current_.scopes[Scope::MC_MARK_CODE_FLUSH],
+                   current_.scopes[Scope::MC_STORE_BUFFER_CLEAR],
+                   current_.scopes[Scope::MC_SLOTS_BUFFER_CLEAR],
                    current_.scopes[Scope::MC_SWEEP],
                    current_.scopes[Scope::MC_SWEEP_NEWSPACE],
                    current_.scopes[Scope::MC_SWEEP_OLDSPACE],

src/heap/gc-tracer.h

@@ -109,6 +109,8 @@ class GCTracer {
       MC_MARK_WEAK_REFERENCES,
       MC_MARK_GLOBAL_HANDLES,
       MC_MARK_CODE_FLUSH,
+      MC_STORE_BUFFER_CLEAR,
+      MC_SLOTS_BUFFER_CLEAR,
       MC_SWEEP,
       MC_SWEEP_NEWSPACE,
       MC_SWEEP_OLDSPACE,

src/heap/mark-compact.cc

@@ -297,12 +297,20 @@ bool MarkCompactCollector::StartCompaction(CompactionMode mode) {
 
 
 void MarkCompactCollector::ClearInvalidStoreAndSlotsBufferEntries() {
-  heap_->store_buffer()->ClearInvalidStoreBufferEntries();
+  {
+    GCTracer::Scope gc_scope(heap()->tracer(),
+                             GCTracer::Scope::MC_STORE_BUFFER_CLEAR);
+    heap_->store_buffer()->ClearInvalidStoreBufferEntries();
+  }
 
-  int number_of_pages = evacuation_candidates_.length();
-  for (int i = 0; i < number_of_pages; i++) {
-    Page* p = evacuation_candidates_[i];
-    SlotsBuffer::RemoveInvalidSlots(heap_, p->slots_buffer());
+  {
+    GCTracer::Scope gc_scope(heap()->tracer(),
+                             GCTracer::Scope::MC_SLOTS_BUFFER_CLEAR);
+    int number_of_pages = evacuation_candidates_.length();
+    for (int i = 0; i < number_of_pages; i++) {
+      Page* p = evacuation_candidates_[i];
+      SlotsBuffer::RemoveInvalidSlots(heap_, p->slots_buffer());
+    }
   }
 }