[heap] Create a thin wrapper around wrapper tracing in V8 to avoid misuse

src/heap/mark-compact.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/mark-compact.h"
 
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
 #include "src/base/sys-info.h"
 #include "src/code-stubs.h"
@@ skipping 778 matching lines @@
 
   // Clear marking bits if incremental marking is aborted.
   if (was_marked_incrementally_ && heap_->ShouldAbortIncrementalMarking()) {
     heap()->incremental_marking()->Stop();
     heap()->incremental_marking()->AbortBlackAllocation();
     ClearMarkbits();
     AbortWeakCollections();
     AbortWeakCells();
     AbortTransitionArrays();
     AbortCompaction();
-    if (heap_->UsingEmbedderHeapTracer()) {
-      heap_->embedder_heap_tracer()->AbortTracing();
-      heap_->clear_wrappers_to_trace();
-    }
+    heap_->local_embedder_heap_tracer()->AbortTracing();
     marking_deque()->Clear();
     was_marked_incrementally_ = false;
   }
 
   if (!was_marked_incrementally_) {
-    if (heap_->UsingEmbedderHeapTracer()) {
-      TRACE_GC(heap()->tracer(), GCTracer::Scope::MC_MARK_WRAPPER_PROLOGUE);
-      heap_->embedder_heap_tracer()->TracePrologue();
-    }
+    TRACE_GC(heap()->tracer(), GCTracer::Scope::MC_MARK_WRAPPER_PROLOGUE);
+    heap_->local_embedder_heap_tracer()->TracePrologue();
   }
 
-  if (heap_->UsingEmbedderHeapTracer()) {
-    heap_->embedder_heap_tracer()->EnterFinalPause();
-  }
+  heap_->local_embedder_heap_tracer()->EnterFinalPause();
 
   // Don't start compaction if we are in the middle of incremental
   // marking cycle. We did not collect any slots.
   if (!FLAG_never_compact && !was_marked_incrementally_) {
     StartCompaction();
   }
 
   PagedSpaces spaces(heap());
   for (PagedSpace* space = spaces.next(); space != NULL;
        space = spaces.next()) {
@@ skipping 1307 matching lines @@
 }
 
 // Mark all objects reachable (transitively) from objects on the marking
 // stack including references only considered in the atomic marking pause.
 void MarkCompactCollector::ProcessEphemeralMarking(
     ObjectVisitor* visitor, bool only_process_harmony_weak_collections) {
   DCHECK(marking_deque()->IsEmpty() && !marking_deque()->overflowed());
   bool work_to_do = true;
   while (work_to_do) {
     if (!only_process_harmony_weak_collections) {
-      if (heap_->UsingEmbedderHeapTracer()) {
+      if (heap_->local_embedder_heap_tracer()->InUse()) {
         TRACE_GC(heap()->tracer(), GCTracer::Scope::MC_MARK_WRAPPER_TRACING);
-        heap_->RegisterWrappersWithEmbedderHeapTracer();
-        heap_->embedder_heap_tracer()->AdvanceTracing(
+        heap_->local_embedder_heap_tracer()->Trace(
             0,
             EmbedderHeapTracer::AdvanceTracingActions(
                 EmbedderHeapTracer::ForceCompletionAction::FORCE_COMPLETION));
       } else {
         TRACE_GC(heap()->tracer(), GCTracer::Scope::MC_MARK_OBJECT_GROUPING);
         isolate()->global_handles()->IterateObjectGroups(
             visitor, &IsUnmarkedHeapObjectWithHeap);
         MarkImplicitRefGroups(&MarkCompactMarkingVisitor::MarkObject);
       }
     } else {
       // TODO(mlippautz): We currently do not trace through blink when
       // discovering new objects reachable from weak roots (that have been made
       // strong). This is a limitation of not having a separate handle type
       // that doesn't require zapping before this phase. See crbug.com/668060.
-      heap_->clear_wrappers_to_trace();
+      heap_->local_embedder_heap_tracer()->ClearCachedWrappersToTrace();
     }
     ProcessWeakCollections();
     work_to_do = !marking_deque()->IsEmpty();
     ProcessMarkingDeque<MarkCompactMode::FULL>();
   }
   CHECK(heap_->MarkingDequesAreEmpty());
 }
 
 void MarkCompactCollector::ProcessTopOptimizedFrame(ObjectVisitor* visitor) {
   for (StackFrameIterator it(isolate(), isolate()->thread_local_top());
@@ skipping 322 matching lines @@
     }
 
     // Repeat Harmony weak maps marking to mark unmarked objects reachable from
     // the weak roots we just marked as pending destruction.
     //
     // We only process harmony collections, as all object groups have been fully
     // processed and no weakly reachable node can discover new objects groups.
     {
       TRACE_GC(heap()->tracer(), GCTracer::Scope::MC_MARK_WEAK_CLOSURE_HARMONY);
       ProcessEphemeralMarking(&root_visitor, true);
-      if (heap_->UsingEmbedderHeapTracer()) {
+      {
         TRACE_GC(heap()->tracer(), GCTracer::Scope::MC_MARK_WRAPPER_EPILOGUE);
-        heap()->embedder_heap_tracer()->TraceEpilogue();
+        heap()->local_embedder_heap_tracer()->TraceEpilogue();
       }
     }
   }
 }
 
 
 void MarkCompactCollector::ClearNonLiveReferences() {
   TRACE_GC(heap()->tracer(), GCTracer::Scope::MC_CLEAR);
 
   {
@@ skipping 1570 matching lines @@
       // The target is always in old space, we don't have to record the slot in
       // the old-to-new remembered set.
       DCHECK(!heap()->InNewSpace(target));
       RecordRelocSlot(host, &rinfo, target);
     }
   }
 }
 
 }  // namespace internal
 }  // namespace v8