[modules] Give Module an internal [hash] field

src/factory.cc

 // Copyright 2014 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/factory.h"
 
 #include "src/accessors.h"
 #include "src/allocation-site-scopes.h"
 #include "src/base/bits.h"
 #include "src/bootstrapper.h"
@@ skipping 1744 matching lines @@
 Handle<Module> Factory::NewModule(Handle<SharedFunctionInfo> code) {
   Handle<ModuleInfo> module_info(code->scope_info()->ModuleDescriptorInfo(),
                                  isolate());
   Handle<ObjectHashTable> exports =
       ObjectHashTable::New(isolate(), module_info->regular_exports()->length());
   int requested_modules_length = module_info->module_requests()->length();
   Handle<FixedArray> requested_modules =
       requested_modules_length > 0 ? NewFixedArray(requested_modules_length)
                                    : empty_fixed_array();
 
-  // To make it easy to hash Modules, we set a new symbol as the name of
-  // SharedFunctionInfo representing this Module.
-  Handle<Symbol> name_symbol = NewSymbol();
-  code->set_name(*name_symbol);
-
   Handle<Module> module = Handle<Module>::cast(NewStruct(MODULE_TYPE));
   module->set_code(*code);
   module->set_embedder_data(isolate()->heap()->undefined_value());
   module->set_exports(*exports);
   module->set_flags(0);
   module->set_module_namespace(isolate()->heap()->undefined_value());
   module->set_requested_modules(*requested_modules);
+  module->set_embedder_data(isolate()->heap()->undefined_value());
+  module->set_hash(isolate()->GenerateIdentityHash(Smi::kMaxValue));
   return module;
 }
 
 Handle<JSArrayBuffer> Factory::NewJSArrayBuffer(SharedFlag shared,
                                                 PretenureFlag pretenure) {
   Handle<JSFunction> array_buffer_fun(
       shared == SharedFlag::kShared
           ? isolate()->native_context()->shared_array_buffer_fun()
           : isolate()->native_context()->array_buffer_fun());
   CALL_HEAP_FUNCTION(isolate(), isolate()->heap()->AllocateJSObject(
@@ skipping 821 matching lines @@
     Handle<AccessorInfo> prototype =
         Accessors::FunctionPrototypeInfo(isolate(), attribs);
     AccessorConstantDescriptor d(Handle<Name>(Name::cast(prototype->name())),
                                  prototype, attribs);
     map->AppendDescriptor(&d);
   }
 }
 
 }  // namespace internal
 }  // namespace v8