Implement IdentityMap<V>, a robust, GC-safe object-identity HashMap.

src/heap/heap.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_HEAP_HEAP_H_
 #define V8_HEAP_HEAP_H_
 
 #include <cmath>
 
 #include "src/allocation.h"
@@ skipping 1433 matching lines @@
   void RecordFixedArraySubTypeStats(int array_sub_type, size_t size) {
     DCHECK(array_sub_type <= LAST_FIXED_ARRAY_SUB_TYPE);
     object_counts_[FIRST_FIXED_ARRAY_SUB_TYPE + array_sub_type]++;
     object_sizes_[FIRST_FIXED_ARRAY_SUB_TYPE + array_sub_type] += size;
   }
 
   void TraceObjectStats();
   void TraceObjectStat(const char* name, int count, int size, double time);
   void CheckpointObjectStats();
 
+  struct StrongRootsList {
+    Object** start_;
+    Object** end_;
+    StrongRootsList* next_;
+  };
+
+  void RegisterStrongRoots(Object** start, Object** end) {
+    StrongRootsList* list = new StrongRootsList();
+    list->next_ = strong_roots_list_;
+    list->start_ = start;
+    list->end_ = end;
+    strong_roots_list_ = list;
+  }
+
+  void UnregisterStrongRoots(Object** start) {
+    StrongRootsList* prev = NULL;
+    for (StrongRootsList* list = strong_roots_list_; list; list = list->next_) {
+      if (list->start_ == start) {
+        if (prev) {
+          prev->next_ = list->next_;
+        } else {
+          strong_roots_list_ = list->next_;
+        }
+        delete list;
+      }
+      prev = list;
+    }
+  }
+
+  base::Mutex* relocation_mutex() { return &relocation_mutex_; }
+
   // We don't use a LockGuard here since we want to lock the heap
   // only when FLAG_concurrent_recompilation is true.
   class RelocationLock {
    public:
     explicit RelocationLock(Heap* heap) : heap_(heap) {
       heap_->relocation_mutex_.Lock();
     }
 
 
     ~RelocationLock() { heap_->relocation_mutex_.Unlock(); }
@@ skipping 680 matching lines @@
   MemoryChunk* chunks_queued_for_free_;
 
   base::Mutex relocation_mutex_;
 
   int gc_callbacks_depth_;
 
   bool deserialization_complete_;
 
   bool concurrent_sweeping_enabled_;
 
+  StrongRootsList* strong_roots_list_;
+
   friend class AlwaysAllocateScope;
   friend class Deserializer;
   friend class Factory;
   friend class GCCallbacksScope;
   friend class GCTracer;
   friend class HeapIterator;
   friend class Isolate;
   friend class MarkCompactCollector;
   friend class MarkCompactMarkingVisitor;
   friend class MapCompact;
@@ skipping 441 matching lines @@
   DisallowHeapAllocation no_allocation;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_HEAP_H_