cppgc: Populate TraceSummary in TraceEpilogue

This was missing in CppHeap which means the used_bytes counter in
EmbedderTracing was reset to 0 after every GC.

Bug: chromium:1056170
Change-Id: Iddb0aa1eff9cc354622653376c6623364e015c5d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2732668
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73167}

src/heap/cppgc-js/cpp-heap.cc

@@ -384,6 +384,9 @@ void CppHeap::TraceEpilogue(TraceSummary* trace_summary) {
             sweeping_config.sweeping_type);
     sweeper().Start(sweeping_config);
   }
+  DCHECK_NOT_NULL(trace_summary);
+  trace_summary->allocated_size = stats_collector_->marked_bytes();
+  trace_summary->time = stats_collector_->marking_time().InMillisecondsF();
   in_atomic_pause_ = false;
   sweeper().NotifyDoneIfNeeded();
 }
@@ -431,7 +434,8 @@ void CppHeap::CollectGarbageForTesting(
     TracePrologue(TraceFlags::kForced);
     EnterFinalPause(stack_state);
     AdvanceTracing(std::numeric_limits<double>::infinity());
-    TraceEpilogue(nullptr);
+    TraceSummary trace_summary;
+    TraceEpilogue(&trace_summary);
   }
 }
 

src/heap/cppgc/stats-collector.cc

@@ -7,7 +7,9 @@
 #include <algorithm>
 #include <cmath>
 
+#include "src/base/atomicops.h"
 #include "src/base/logging.h"
+#include "src/base/platform/time.h"
 #include "src/heap/cppgc/metric-recorder.h"
 
 namespace cppgc {
@@ -234,6 +236,28 @@ size_t StatsCollector::allocated_object_size() const {
                              allocated_bytes_since_end_of_marking_);
 }
 
+size_t StatsCollector::marked_bytes() const {
+  DCHECK_NE(GarbageCollectionState::kMarking, gc_state_);
+  // During sweeping we refer to the current Event as that already holds the
+  // correct marking information. In all other phases, the previous event holds
+  // the most up-to-date marking information.
+  const Event& event =
+      gc_state_ == GarbageCollectionState::kSweeping ? current_ : previous_;
+  return event.marked_bytes;
+}
+
+v8::base::TimeDelta StatsCollector::marking_time() const {
+  DCHECK_NE(GarbageCollectionState::kMarking, gc_state_);
+  // During sweeping we refer to the current Event as that already holds the
+  // correct marking information. In all other phases, the previous event holds
+  // the most up-to-date marking information.
+  const Event& event =
+      gc_state_ == GarbageCollectionState::kSweeping ? current_ : previous_;
+  return event.scope_data[kAtomicMark] + event.scope_data[kIncrementalMark] +
+         v8::base::TimeDelta::FromMicroseconds(v8::base::Relaxed_Load(
+             &event.concurrent_scope_data[kConcurrentMark]));
+}
+
 void StatsCollector::NotifyAllocatedMemory(int64_t size) {
   memory_allocated_bytes_ += size;
   ForAllAllocationObservers([size](AllocationObserver* observer) {

src/heap/cppgc/stats-collector.h

@@ -275,6 +275,13 @@ class V8_EXPORT_PRIVATE StatsCollector final {
   // bytes and the bytes allocated since last marking.
   size_t allocated_object_size() const;
 
+  // Returns the most recent marked bytes count. Should not be called during
+  // marking.
+  size_t marked_bytes() const;
+  // Returns the overall duration of the most recent marking phase. Should not
+  // be called during marking.
+  v8::base::TimeDelta marking_time() const;
+
   double GetRecentAllocationSpeedInBytesPerMs() const;
 
   const Event& GetPreviousEventForTesting() const { return previous_; }