Use WeakCells in the optimized code map rather than traversing in pause.

src/heap/objects-visiting-inl.h

 // 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.
 
 #ifndef V8_OBJECTS_VISITING_INL_H_
 #define V8_OBJECTS_VISITING_INL_H_
 
 #include "src/heap/array-buffer-tracker.h"
 #include "src/heap/objects-visiting.h"
 #include "src/ic/ic-state.h"
@@ skipping 430 matching lines @@
     shared->ResetForNewContext(heap->global_ic_age());
   }
   if (FLAG_cleanup_code_caches_at_gc) {
     shared->ClearTypeFeedbackInfoAtGCTime();
   }
   if (FLAG_flush_optimized_code_cache) {
     if (!shared->OptimizedCodeMapIsCleared()) {
       // Always flush the optimized code map if requested by flag.
       shared->ClearOptimizedCodeMap();
     }
-  } else {
-    if (!shared->OptimizedCodeMapIsCleared()) {
-      // Treat some references within the code map weakly by marking the
-      // code map itself but not pushing it onto the marking deque. The
-      // map will be processed after marking.
-      FixedArray* code_map = shared->optimized_code_map();
-      MarkOptimizedCodeMap(heap, code_map);
-    }
   }
   MarkCompactCollector* collector = heap->mark_compact_collector();
   if (collector->is_code_flushing_enabled()) {
     if (IsFlushable(heap, shared)) {
       // This function's code looks flushable. But we have to postpone
       // the decision until we see all functions that point to the same
       // SharedFunctionInfo because some of them might be optimized.
       // That would also make the non-optimized version of the code
       // non-flushable, because it is required for bailing out from
       // optimized code.
@@ skipping 118 matching lines @@
                                 transitions->GetPrototypeTransitionsSlot());
   }
 
   int num_transitions = TransitionArray::NumberOfTransitions(transitions);
   for (int i = 0; i < num_transitions; ++i) {
     StaticVisitor::VisitPointer(heap, transitions, transitions->GetKeySlot(i));
   }
 }
 
 
-template <typename StaticVisitor>
-void StaticMarkingVisitor<StaticVisitor>::MarkOptimizedCodeMap(
-    Heap* heap, FixedArray* code_map) {
-  if (!StaticVisitor::MarkObjectWithoutPush(heap, code_map)) return;
-
-  // Mark the context-independent entry in the optimized code map. Depending on
-  // the age of the code object, we treat it as a strong or a weak reference.
-  Object* shared_object = code_map->get(SharedFunctionInfo::kSharedCodeIndex);
-  if (FLAG_turbo_preserve_shared_code && shared_object->IsCode() &&
-      FLAG_age_code && !Code::cast(shared_object)->IsOld()) {
-    StaticVisitor::VisitPointer(
-        heap, code_map,
-        code_map->RawFieldOfElementAt(SharedFunctionInfo::kSharedCodeIndex));
-  }
-}
-
-
 inline static bool HasSourceCode(Heap* heap, SharedFunctionInfo* info) {
   Object* undefined = heap->undefined_value();
   return (info->script() != undefined) &&
          (reinterpret_cast<Script*>(info->script())->source() != undefined);
 }
 
 
 template <typename StaticVisitor>
 bool StaticMarkingVisitor<StaticVisitor>::IsFlushable(Heap* heap,
                                                       JSFunction* function) {
@@ skipping 136 matching lines @@
   typedef FlexibleBodyVisitor<StaticVisitor, JSFunction::BodyDescriptorWeakCode,
                               void> JSFunctionWeakCodeBodyVisitor;
   JSFunctionWeakCodeBodyVisitor::Visit(map, object);
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_OBJECTS_VISITING_INL_H_