[wasm] WebAssembly.Memory object can be referenced by multiple Instance objects.

src/wasm/wasm-module.h

Index: src/wasm/wasm-module.h
diff --git a/src/wasm/wasm-module.h b/src/wasm/wasm-module.h
index 3ac410476d7c6fc9a6a0752f1b7fccb5016a384d..3e159421c3342cdd699e8387ae59868c3d66f58f 100644
--- a/src/wasm/wasm-module.h
+++ b/src/wasm/wasm-module.h
@@ -554,14 +554,74 @@ Object* GetOwningWasmInstance(Code* code);
 MaybeHandle<JSArrayBuffer> GetInstanceMemory(Isolate* isolate,
                                              Handle<JSObject> instance);
 
+void SetInstanceMemoryObject(Handle<JSObject> instance,
+                             Handle<Object> mem_object);
+
 int32_t GetInstanceMemorySize(Isolate* isolate, Handle<JSObject> instance);
 
-int32_t GrowInstanceMemory(Isolate* isolate, Handle<JSObject> instance,
-                           uint32_t pages);
+int32_t GrowWebAssemblyMemory(Isolate* isolate, Handle<Object> memory_object,
+                              uint32_t pages);
+
+int32_t GrowMemory(Isolate* isolate, Handle<JSObject> instance, uint32_t pages);
 
 void UpdateDispatchTables(Isolate* isolate, Handle<FixedArray> dispatch_tables,
                           int index, Handle<JSFunction> js_function);
 
+class WasmInstanceWrapper : public FixedArray {
+ public:
+  static Handle<WasmInstanceWrapper> New(Isolate* isolate,
+                                         Handle<JSObject> instance);
+  static WasmInstanceWrapper* cast(Object* fixed_array) {
+    SLOW_DCHECK(IsWasmInstanceWrapper(fixed_array));
+    return reinterpret_cast<WasmInstanceWrapper*>(fixed_array);
+  }
+  static bool IsWasmInstanceWrapper(Object* obj);
+  bool has_instance() { return get(kWrapperInstanceObject)->IsWeakCell(); }
+  Handle<JSObject> instance_object() {
+    Object* obj = get(kWrapperInstanceObject);
+    DCHECK(obj->IsWeakCell());
+    WeakCell* cell = WeakCell::cast(obj);
+    DCHECK(cell->value()->IsJSObject());
+    return handle(JSObject::cast(cell->value()));
+  }
+  bool has_next() { return IsWasmInstanceWrapper(get(kNextInstanceWrapper)); }
+  bool has_previous() {
+    return IsWasmInstanceWrapper(get(kPreviousInstanceWrapper));
+  }
+  void set_instance_object(Handle<JSObject> instance, Isolate* isolate);
+  void set_next_wrapper(Object* obj) {
+    DCHECK(IsWasmInstanceWrapper(obj));
+    set(kNextInstanceWrapper, obj);
+  }
+  void set_previous_wrapper(Object* obj) {
+    DCHECK(IsWasmInstanceWrapper(obj));
+    set(kPreviousInstanceWrapper, obj);
+  }
+  Handle<WasmInstanceWrapper> next_wrapper() {
+    Object* obj = get(kNextInstanceWrapper);
+    DCHECK(IsWasmInstanceWrapper(obj));
+    return handle(WasmInstanceWrapper::cast(obj));
+  }
+  Handle<WasmInstanceWrapper> previous_wrapper() {
+    Object* obj = get(kPreviousInstanceWrapper);
+    DCHECK(IsWasmInstanceWrapper(obj));
+    return handle(WasmInstanceWrapper::cast(obj));
+  }
+  void reset_next_wrapper() { set_undefined(kNextInstanceWrapper); }
+  void reset_previous_wrapper() { set_undefined(kPreviousInstanceWrapper); }
+  void reset() {
+    for (int kID = 0; kID < kWrapperPropertyCount; kID++) set_undefined(kID);
+  }
+
+ private:
+  enum {
+    kWrapperInstanceObject,
+    kNextInstanceWrapper,
+    kPreviousInstanceWrapper,
+    kWrapperPropertyCount
+  };
+};
+
 namespace testing {
 
 void ValidateInstancesChain(Isolate* isolate, Handle<JSObject> wasm_module,