[heap] Add remembered set processing to GCTracer

Measure remembered set processing during Scavenge.

Change-Id: I8f7f31269bf1c09ff1f3cb3455fc96bce5c4f35d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1895562
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64755}

src/heap/gc-tracer.cc

@@ -564,6 +564,7 @@ void GCTracer::PrintNVP() const {
           "fast_promote=%.2f "
           "scavenge=%.2f "
           "scavenge.process_array_buffers=%.2f "
+          "scavenge.free_remembered_set=%.2f "
           "scavenge.roots=%.2f "
           "scavenge.weak=%.2f "
           "scavenge.weak_global_handles.identify=%.2f "
@@ -604,6 +605,7 @@ void GCTracer::PrintNVP() const {
           current_.scopes[Scope::SCAVENGER_FAST_PROMOTE],
           current_.scopes[Scope::SCAVENGER_SCAVENGE],
           current_.scopes[Scope::SCAVENGER_PROCESS_ARRAY_BUFFERS],
+          current_.scopes[Scope::SCAVENGER_FREE_REMEMBERED_SET],
           current_.scopes[Scope::SCAVENGER_SCAVENGE_ROOTS],
           current_.scopes[Scope::SCAVENGER_SCAVENGE_WEAK],
           current_

src/heap/scavenger.cc

@@ -360,9 +360,14 @@ void ScavengerCollector::CollectGarbage() {
   // TODO(hpayer): Don't free all as soon as we have an intermediate generation.
   heap_->new_lo_space()->FreeDeadObjects([](HeapObject) { return true; });
 
-  RememberedSet<OLD_TO_NEW>::IterateMemoryChunks(heap_, [](MemoryChunk* chunk) {
+  {
+    TRACE_GC(heap_->tracer(), GCTracer::Scope::SCAVENGER_FREE_REMEMBERED_SET);
+
+    RememberedSet<OLD_TO_NEW>::IterateMemoryChunks(
+        heap_, [](MemoryChunk* chunk) {
           RememberedSet<OLD_TO_NEW>::FreeEmptyBuckets(chunk);
         });
+  }
 
   // Update how much has survived scavenge.
   heap_->IncrementYoungSurvivorsCounter(heap_->SurvivedYoungObjectSize());

src/init/heap-symbols.h

@@ -475,6 +475,7 @@
   F(MINOR_MC_RESET_LIVENESS)                         \
   F(MINOR_MC_SWEEPING)                               \
   F(SCAVENGER_FAST_PROMOTE)                          \
+  F(SCAVENGER_FREE_REMEMBERED_SET)                   \
   F(SCAVENGER_SCAVENGE)                              \
   F(SCAVENGER_PROCESS_ARRAY_BUFFERS)                 \
   F(SCAVENGER_SCAVENGE_WEAK_GLOBAL_HANDLES_IDENTIFY) \