[wasm] Remove {NativeModule::module_object} field.

R=titzer@chromium.org
BUG=v8:7424

Change-Id: I1e5f41fba6cc575001cac1fd0a862736784a2131
Reviewed-on: https://chromium-review.googlesource.com/1113456
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54021}

src/wasm/wasm-code-manager.cc

@@ -442,20 +442,6 @@ void NativeModule::SetRuntimeStubs(Isolate* isolate) {
 #undef COPY_BUILTIN
 }
 
-WasmModuleObject* NativeModule::module_object() const {
-  DCHECK_NOT_NULL(module_object_);
-  return *module_object_;
-}
-
-void NativeModule::SetModuleObject(Handle<WasmModuleObject> module_object) {
-  DCHECK_NULL(module_object_);
-  module_object_ = module_object->GetIsolate()
-                       ->global_handles()
-                       ->Create(*module_object)
-                       .location();
-  GlobalHandles::MakeWeak(reinterpret_cast<Object***>(&module_object_));
-}
-
 WasmCode* NativeModule::AddAnonymousCode(Handle<Code> code,
                                          WasmCode::Kind kind) {
   std::unique_ptr<byte[]> reloc_info;
@@ -732,14 +718,6 @@ void NativeModule::DisableTrapHandler() {
 
 NativeModule::~NativeModule() {
   TRACE_HEAP("Deleting native module: %p\n", reinterpret_cast<void*>(this));
-  // Clear the handle at the beginning of destructor to make it robust against
-  // potential GCs in the rest of the destructor.
-  if (module_object_ != nullptr) {
-    Isolate* isolate = module_object()->GetIsolate();
-    isolate->global_handles()->Destroy(
-        reinterpret_cast<Object**>(module_object_));
-    module_object_ = nullptr;
-  }
   wasm_code_manager_->FreeNativeModule(this);
 }
 

src/wasm/wasm-code-manager.h

@@ -311,11 +311,6 @@ class V8_EXPORT_PRIVATE NativeModule final {
 
   CompilationState* compilation_state() { return compilation_state_.get(); }
 
-  // TODO(mstarzinger): The link to the {WasmModuleObject} is deprecated and
-  // all uses should vanish to make {NativeModule} independent of the Isolate.
-  WasmModuleObject* module_object() const;
-  void SetModuleObject(Handle<WasmModuleObject>);
-
   uint32_t num_functions() const { return num_functions_; }
   uint32_t num_imported_functions() const { return num_imported_functions_; }
   Vector<WasmCode*> code_table() const {
@@ -399,11 +394,6 @@ class V8_EXPORT_PRIVATE NativeModule final {
 
   std::unique_ptr<CompilationState, CompilationStateDeleter> compilation_state_;
 
-  // A phantom reference to the {WasmModuleObject}. It is intentionally not
-  // typed {Handle<WasmModuleObject>} because this location will be cleared
-  // when the phantom reference is cleared.
-  WasmModuleObject** module_object_ = nullptr;
-
   DisjointAllocationPool free_code_space_;
   DisjointAllocationPool allocated_code_space_;
   std::list<VirtualMemory> owned_code_space_;

src/wasm/wasm-objects.cc

@@ -307,13 +307,11 @@ Handle<WasmModuleObject> WasmModuleObject::New(
     module_object->set_asm_js_offset_table(*asm_js_offset_table);
   }
 
-  // Create the {NativeModule}, and link it bidirectionally to the
-  // {WasmModuleObject}.
+  // Create the {NativeModule}, and let the {WasmModuleObject} reference it.
   size_t memory_estimate =
       isolate->wasm_engine()->code_manager()->EstimateNativeModuleSize(module);
   auto native_module =
       isolate->wasm_engine()->code_manager()->NewNativeModule(isolate, env);
-  native_module->SetModuleObject(module_object);
   native_module->set_wire_bytes(std::move(wire_bytes), wire_bytes_len);
   native_module->SetRuntimeStubs(isolate);
   Handle<Managed<wasm::NativeModule>> managed_native_module =