[wrapper-tracing] Reduce marking overhead: Tri-color marking without 3 colors

third_party/WebKit/Source/platform/heap/TraceTraits.h

Index: third_party/WebKit/Source/platform/heap/TraceTraits.h
diff --git a/third_party/WebKit/Source/platform/heap/TraceTraits.h b/third_party/WebKit/Source/platform/heap/TraceTraits.h
index a56ccf1a0f3d4a5cebfea9e0068a3adaed65eb1d..1a28b07e9082965a0e212769133b48cf1865aabe 100644
--- a/third_party/WebKit/Source/platform/heap/TraceTraits.h
+++ b/third_party/WebKit/Source/platform/heap/TraceTraits.h
@@ -47,12 +47,22 @@ class AdjustAndMarkTrait<T, false> {
   STATIC_ONLY(AdjustAndMarkTrait);
 
  public:
-  static void markWrapper(const WrapperVisitor* visitor, const T* t) {
+  static void fullyMarkAndTraceWrapper(const WrapperVisitor* visitor,
+                                       const T* t) {

[Hannes Payer (out of office), 2016/12/20 15:30:33]

DCHECK(!heapObjectHeader(t)->isWrapperHeaderMarked());

[Michael Lippautz, 2016/12/20 15:57:23]

This one cannot be done, as it is used when we cannot eagerly process an object
in mixin construction. It has to stay conditional.

     if (visitor->markWrapperHeader(heapObjectHeader(t))) {
       visitor->markWrappersInAllWorlds(t);
       visitor->dispatchTraceWrappers(t);
     }
   }
+  static void markWrapperHeaderOnly(const WrapperVisitor* visitor, const T* t) {

[Hannes Payer (out of office), 2016/12/20 15:30:33]

DCHECK(!heapObjectHeader(t)->isWrapperHeaderMarked());

[Michael Lippautz, 2016/12/20 15:57:23]

Done.

+    visitor->markWrapperHeader(heapObjectHeader(t));
+  }
+  static void finishMarkAndTraceMarkedWrapper(const WrapperVisitor* visitor,
+                                              const T* t) {
+    CHECK(heapObjectHeader(t)->isWrapperHeaderMarked());

[Hannes Payer (out of office), 2016/12/20 15:30:34]

s/CHECK/DCHECK/

[Michael Lippautz, 2016/12/20 15:57:23]

Most of the assertions will be CHECKs until this is stabilized a bit more.

+    visitor->markWrappersInAllWorlds(t);
+    visitor->dispatchTraceWrappers(t);
+  }
   static HeapObjectHeader* heapObjectHeader(const T* t) {
     return HeapObjectHeader::fromPayload(t);
   }
@@ -99,8 +109,16 @@ class AdjustAndMarkTrait<T, true> {
   STATIC_ONLY(AdjustAndMarkTrait);
 
  public:
-  static void markWrapper(const WrapperVisitor* visitor, const T* t) {
-    t->adjustAndMarkWrapper(visitor);
+  static void fullyMarkAndTraceWrapper(const WrapperVisitor* visitor,
+                                       const T* t) {
+    t->adjustAndFullyMarkAndTraceWrapper(visitor);
+  }
+  static void markWrapperHeaderOnly(const WrapperVisitor* visitor, const T* t) {
+    t->adjustAndMarkWrapperHeaderOnly(visitor);
+  }
+  static void finishMarkAndTraceMarkedWrapper(const WrapperVisitor* visitor,
+                                              const T* t) {
+    t->adjustAndFinishMarkAndTraceMarkedWrapper(visitor);
   }
   static HeapObjectHeader* heapObjectHeader(const T* t) {
     return t->adjustAndGetHeapObjectHeader();
@@ -205,11 +223,29 @@ class TraceTrait {
   static void trace(Visitor*, void* self);
   static void trace(InlinedGlobalMarkingVisitor, void* self);
 
-  static void markWrapper(const WrapperVisitor* visitor, const void* t) {
+  static void fullyMarkAndTraceWrapper(const WrapperVisitor* visitor,
+                                       const void* t) {
+    static_assert(CanTraceWrappers<T>::value,
+                  "T should be able to trace wrappers. See "
+                  "dispatchTraceWrappers in WrapperVisitor.h");
+    return AdjustAndMarkTrait<T>::fullyMarkAndTraceWrapper(
+        visitor, reinterpret_cast<const T*>(t));
+  }
+  static void markWrapperHeaderOnly(const WrapperVisitor* visitor,
+                                    const void* t) {
+    static_assert(CanTraceWrappers<T>::value,
+                  "T should be able to trace wrappers. See "
+                  "dispatchTraceWrappers in WrapperVisitor.h");
+    return AdjustAndMarkTrait<T>::markWrapperHeaderOnly(
+        visitor, reinterpret_cast<const T*>(t));
+  }
+  static void finishMarkAndTraceMarkedWrapper(const WrapperVisitor* visitor,
+                                              const void* t) {
     static_assert(CanTraceWrappers<T>::value,
                   "T should be able to trace wrappers. See "
                   "dispatchTraceWrappers in WrapperVisitor.h");
-    AdjustAndMarkTrait<T>::markWrapper(visitor, reinterpret_cast<const T*>(t));
+    AdjustAndMarkTrait<T>::finishMarkAndTraceMarkedWrapper(
+        visitor, reinterpret_cast<const T*>(t));
   }
   static HeapObjectHeader* heapObjectHeader(const void* t) {
     static_assert(CanTraceWrappers<T>::value,