[wasm] Split the compilation and instantiation API into sync and async methods.

src/wasm/wasm-js.cc

 // Copyright 2015 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/api-natives.h"
 #include "src/api.h"
 #include "src/asmjs/asm-js.h"
 #include "src/asmjs/asm-typer.h"
 #include "src/asmjs/asm-wasm-builder.h"
 #include "src/assert-scope.h"
@@ skipping 13 matching lines @@
 #include "src/wasm/wasm-objects.h"
 #include "src/wasm/wasm-result.h"
 
 typedef uint8_t byte;
 
 using v8::internal::wasm::ErrorThrower;
 
 namespace v8 {
 
 namespace {
+// TODO(wasm): move brand check to the respective types, and don't throw
+// in it, rather, use a provided ErrorThrower, or let caller handle it.
+static bool HasBrand(i::Handle<i::Object> value, i::Handle<i::Symbol> sym) {
+  if (!value->IsJSObject()) return false;
+  i::Handle<i::JSObject> object = i::Handle<i::JSObject>::cast(value);
+  Maybe<bool> has_brand = i::JSObject::HasOwnProperty(object, sym);
+  return has_brand.FromMaybe(false);
+}
+
+static bool BrandCheck(i::Handle<i::Object> value, i::Handle<i::Symbol> sym,
+                       ErrorThrower* thrower, const char* msg) {
+  return HasBrand(value, sym) ? true : (thrower->TypeError("%s", msg), false);
+}
+
 i::Handle<i::String> v8_str(i::Isolate* isolate, const char* str) {
   return isolate->factory()->NewStringFromAsciiChecked(str);
 }
 Local<String> v8_str(Isolate* isolate, const char* str) {
   return Utils::ToLocal(v8_str(reinterpret_cast<i::Isolate*>(isolate), str));
 }
 
-struct RawBuffer {
-  const byte* start;
-  const byte* end;
-  size_t size() { return static_cast<size_t>(end - start); }
-};
+i::MaybeHandle<i::WasmModuleObject> GetFirstArgumentAsModule(
+    const v8::FunctionCallbackInfo<v8::Value>& args, ErrorThrower* thrower) {
+  v8::Isolate* isolate = args.GetIsolate();
+  if (args.Length() < 1) {
+    thrower->TypeError("Argument 0 must be a WebAssembly.Module");
+    return {};
+  }
 
-RawBuffer GetRawBufferSource(
-    v8::Local<v8::Value> source, ErrorThrower* thrower) {
+  Local<Context> context = isolate->GetCurrentContext();
+  i::Handle<i::Context> i_context = Utils::OpenHandle(*context);
+  if (!BrandCheck(Utils::OpenHandle(*args[0]),
+                  i::handle(i_context->wasm_module_sym()), thrower,
+                  "Argument 0 must be a WebAssembly.Module")) {
+    return {};
+  }
+
+  Local<Object> module_obj = Local<Object>::Cast(args[0]);
+  return i::Handle<i::WasmModuleObject>::cast(
+      v8::Utils::OpenHandle(*module_obj));
+}
+
+i::wasm::ModuleWireBytes GetFirstArgumentAsBytes(
+    const v8::FunctionCallbackInfo<v8::Value>& args, ErrorThrower* thrower) {
+  if (args.Length() < 1) {
+    thrower->TypeError("Argument 0 must be a buffer source");
+    return i::wasm::ModuleWireBytes(nullptr, nullptr);
+  }
+
   const byte* start = nullptr;
   const byte* end = nullptr;
-
+  v8::Local<v8::Value> source = args[0];
   if (source->IsArrayBuffer()) {
     // A raw array buffer was passed.
     Local<ArrayBuffer> buffer = Local<ArrayBuffer>::Cast(source);
     ArrayBuffer::Contents contents = buffer->GetContents();
 
     start = reinterpret_cast<const byte*>(contents.Data());
     end = start + contents.ByteLength();
 
   } else if (source->IsTypedArray()) {
     // A TypedArray was passed.
     Local<TypedArray> array = Local<TypedArray>::Cast(source);
     Local<ArrayBuffer> buffer = array->Buffer();
 
     ArrayBuffer::Contents contents = buffer->GetContents();
 
     start =
         reinterpret_cast<const byte*>(contents.Data()) + array->ByteOffset();
     end = start + array->ByteLength();
 
   } else {
     thrower->TypeError("Argument 0 must be a buffer source");
   }
   if (start == nullptr || end == start) {
     thrower->CompileError("BufferSource argument is empty");
   }
-  return {start, end};
+  // TODO(titzer): use the handle as well?
+  return i::wasm::ModuleWireBytes(start, end);
 }
 
-static i::MaybeHandle<i::WasmModuleObject> CreateModuleObject(
-    v8::Isolate* isolate, const v8::Local<v8::Value> source,
-    ErrorThrower* thrower) {
-  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
-  i::MaybeHandle<i::JSObject> nothing;
+i::MaybeHandle<i::JSReceiver> GetSecondArgumentAsImports(
+    const v8::FunctionCallbackInfo<v8::Value>& args, ErrorThrower* thrower) {
+  if (args.Length() < 2) return {};
+  if (args[1]->IsUndefined()) return {};
 
-  RawBuffer buffer = GetRawBufferSource(source, thrower);
-  if (buffer.start == nullptr) return i::MaybeHandle<i::WasmModuleObject>();
-
-  DCHECK(source->IsArrayBuffer() || source->IsTypedArray());
-  return i::wasm::CreateModuleObjectFromBytes(
-      i_isolate, buffer.start, buffer.end, thrower, i::wasm::kWasmOrigin,
-      i::Handle<i::Script>::null(), i::Vector<const byte>::empty());
+  if (!args[1]->IsObject()) {
+    thrower->TypeError("Argument 1 must be an object");
+    return {};
+  }
+  Local<Object> obj = Local<Object>::Cast(args[1]);
+  return i::Handle<i::JSReceiver>::cast(v8::Utils::OpenHandle(*obj));
 }
 
-static bool ValidateModule(v8::Isolate* isolate,
-                           const v8::Local<v8::Value> source,
-                           ErrorThrower* thrower) {
-  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
-  i::MaybeHandle<i::JSObject> nothing;
-
-  RawBuffer buffer = GetRawBufferSource(source, thrower);
-  if (buffer.start == nullptr) return false;
-
-  DCHECK(source->IsArrayBuffer() || source->IsTypedArray());
-  return i::wasm::ValidateModuleBytes(i_isolate, buffer.start, buffer.end,
-                                      thrower,
-                                      i::wasm::ModuleOrigin::kWasmOrigin);
-}
-
-// TODO(wasm): move brand check to the respective types, and don't throw
-// in it, rather, use a provided ErrorThrower, or let caller handle it.
-static bool HasBrand(i::Handle<i::Object> value, i::Handle<i::Symbol> sym) {
-  if (!value->IsJSObject()) return false;
-  i::Handle<i::JSObject> object = i::Handle<i::JSObject>::cast(value);
-  Maybe<bool> has_brand = i::JSObject::HasOwnProperty(object, sym);
-  return !has_brand.IsNothing() && has_brand.ToChecked();
-}
-
-static bool BrandCheck(ErrorThrower* thrower, i::Handle<i::Object> value,
-                       i::Handle<i::Symbol> sym, const char* msg) {
-  return HasBrand(value, sym) ? true : (thrower->TypeError("%s", msg), false);
-}
-
+// WebAssembly.compile(bytes) -> Promise
 void WebAssemblyCompile(const v8::FunctionCallbackInfo<v8::Value>& args) {
   v8::Isolate* isolate = args.GetIsolate();
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
   HandleScope scope(isolate);
-  ErrorThrower thrower(reinterpret_cast<i::Isolate*>(isolate),
-                       "WebAssembly.compile()");
+  ErrorThrower thrower(i_isolate, "WebAssembly.compile()");
 
   Local<Context> context = isolate->GetCurrentContext();
   v8::Local<v8::Promise::Resolver> resolver;
   if (!v8::Promise::Resolver::New(context).ToLocal(&resolver)) return;
   v8::ReturnValue<v8::Value> return_value = args.GetReturnValue();
   return_value.Set(resolver->GetPromise());
 
-  if (args.Length() < 1) {
-    thrower.TypeError("Argument 0 must be a buffer source");
+  auto bytes = GetFirstArgumentAsBytes(args, &thrower);
+  if (thrower.error()) {
     resolver->Reject(context, Utils::ToLocal(thrower.Reify()));
     return;
   }
-  i::MaybeHandle<i::JSObject> module_obj =
-      CreateModuleObject(isolate, args[0], &thrower);
-
-  if (thrower.error()) {
-    resolver->Reject(context, Utils::ToLocal(thrower.Reify()));
-  } else {
-    resolver->Resolve(context, Utils::ToLocal(module_obj.ToHandleChecked()));
-  }
+  i::Handle<i::JSPromise> promise = Utils::OpenHandle(*resolver->GetPromise());
+  i::wasm::AsyncCompile(i_isolate, promise, bytes);
 }
 
+// WebAssembly.validate(bytes) -> bool
 void WebAssemblyValidate(const v8::FunctionCallbackInfo<v8::Value>& args) {
   v8::Isolate* isolate = args.GetIsolate();
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
   HandleScope scope(isolate);
-  ErrorThrower thrower(reinterpret_cast<i::Isolate*>(isolate),
-                       "WebAssembly.validate()");
+  ErrorThrower thrower(i_isolate, "WebAssembly.validate()");
 
-  if (args.Length() < 1) {
-    thrower.TypeError("Argument 0 must be a buffer source");
-    return;
-  }
+  auto bytes = GetFirstArgumentAsBytes(args, &thrower);
 
   v8::ReturnValue<v8::Value> return_value = args.GetReturnValue();
-  if (ValidateModule(isolate, args[0], &thrower)) {
+  if (!thrower.error() &&
+      i::wasm::SyncValidate(reinterpret_cast<i::Isolate*>(isolate), &thrower,
+                            bytes)) {
     return_value.Set(v8::True(isolate));
   } else {
     if (thrower.wasm_error()) thrower.Reify();  // Clear error.
     return_value.Set(v8::False(isolate));
   }
 }
 
+// new WebAssembly.Module(bytes) -> WebAssembly.Module
 void WebAssemblyModule(const v8::FunctionCallbackInfo<v8::Value>& args) {
   v8::Isolate* isolate = args.GetIsolate();
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
   HandleScope scope(isolate);
-  ErrorThrower thrower(reinterpret_cast<i::Isolate*>(isolate),
-                       "WebAssembly.Module()");
+  ErrorThrower thrower(i_isolate, "WebAssembly.Module()");
 
-  if (args.Length() < 1) {
-    thrower.TypeError("Argument 0 must be a buffer source");
-    return;
-  }
+  auto bytes = GetFirstArgumentAsBytes(args, &thrower);
+  if (thrower.error()) return;
 
-  i::MaybeHandle<i::JSObject> module_obj =
-      CreateModuleObject(isolate, args[0], &thrower);
+  i::MaybeHandle<i::Object> module_obj =
+      i::wasm::SyncCompile(i_isolate, &thrower, bytes);
   if (module_obj.is_null()) return;
 
   v8::ReturnValue<v8::Value> return_value = args.GetReturnValue();
   return_value.Set(Utils::ToLocal(module_obj.ToHandleChecked()));
 }
 
-MaybeLocal<Value> InstantiateModuleImpl(
-    i::Isolate* i_isolate, i::Handle<i::WasmModuleObject> i_module_obj,
-    const v8::FunctionCallbackInfo<v8::Value>& args, ErrorThrower* thrower) {
-  // It so happens that in both the WebAssembly.instantiate, as well as
-  // WebAssembly.Instance ctor, the positions of the ffi object and memory
-  // are the same. If that changes later, we refactor the consts into
-  // parameters.
-  static const int kFfiOffset = 1;
-
-  MaybeLocal<Value> nothing;
-  i::Handle<i::JSReceiver> ffi = i::Handle<i::JSObject>::null();
-  // This is a first - level validation of the argument. If present, we only
-  // check its type. {Instantiate} will further check that if the module
-  // has imports, the argument must be present, as well as piecemeal
-  // import satisfaction.
-  if (args.Length() > kFfiOffset && !args[kFfiOffset]->IsUndefined()) {
-    if (!args[kFfiOffset]->IsObject()) {
-      thrower->TypeError("Argument %d must be an object", kFfiOffset);
-      return nothing;
-    }
-    Local<Object> obj = Local<Object>::Cast(args[kFfiOffset]);
-    ffi = i::Handle<i::JSReceiver>::cast(v8::Utils::OpenHandle(*obj));
-  }
-
-  i::MaybeHandle<i::JSObject> instance =
-      i::wasm::WasmModule::Instantiate(i_isolate, thrower, i_module_obj, ffi);
-  if (instance.is_null()) {
-    if (!thrower->error())
-      thrower->RuntimeError("Could not instantiate module");
-    return nothing;
-  }
-  DCHECK(!i_isolate->has_pending_exception());
-  return Utils::ToLocal(instance.ToHandleChecked());
-}
-
-namespace {
-i::MaybeHandle<i::WasmModuleObject> GetFirstArgumentAsModule(
-    const v8::FunctionCallbackInfo<v8::Value>& args, ErrorThrower* thrower) {
-  v8::Isolate* isolate = args.GetIsolate();
-  i::MaybeHandle<i::WasmModuleObject> nothing;
-  if (args.Length() < 1) {
-    thrower->TypeError("Argument 0 must be a WebAssembly.Module");
-    return nothing;
-  }
-
-  Local<Context> context = isolate->GetCurrentContext();
-  i::Handle<i::Context> i_context = Utils::OpenHandle(*context);
-  if (!BrandCheck(thrower, Utils::OpenHandle(*args[0]),
-                  i::Handle<i::Symbol>(i_context->wasm_module_sym()),
-                  "Argument 0 must be a WebAssembly.Module")) {
-    return nothing;
-  }
-
-  Local<Object> module_obj = Local<Object>::Cast(args[0]);
-  return i::Handle<i::WasmModuleObject>::cast(
-      v8::Utils::OpenHandle(*module_obj));
-}
-}  // namespace
-
+// WebAssembly.Module.imports(module) -> Array<Import>
 void WebAssemblyModuleImports(const v8::FunctionCallbackInfo<v8::Value>& args) {
   HandleScope scope(args.GetIsolate());
   v8::Isolate* isolate = args.GetIsolate();
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
   ErrorThrower thrower(i_isolate, "WebAssembly.Module.imports()");
 
   auto maybe_module = GetFirstArgumentAsModule(args, &thrower);
-
-  if (!maybe_module.is_null()) {
-    auto imports =
-        i::wasm::GetImports(i_isolate, maybe_module.ToHandleChecked());
-    args.GetReturnValue().Set(Utils::ToLocal(imports));
-  }
+  if (thrower.error()) return;
+  auto imports = i::wasm::GetImports(i_isolate, maybe_module.ToHandleChecked());
+  args.GetReturnValue().Set(Utils::ToLocal(imports));
 }
 
+// WebAssembly.Module.exports(module) -> Array<Export>
 void WebAssemblyModuleExports(const v8::FunctionCallbackInfo<v8::Value>& args) {
   HandleScope scope(args.GetIsolate());
   v8::Isolate* isolate = args.GetIsolate();
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
   ErrorThrower thrower(i_isolate, "WebAssembly.Module.exports()");
 
   auto maybe_module = GetFirstArgumentAsModule(args, &thrower);
-
-  if (!maybe_module.is_null()) {
-    auto exports =
-        i::wasm::GetExports(i_isolate, maybe_module.ToHandleChecked());
-    args.GetReturnValue().Set(Utils::ToLocal(exports));
-  }
+  if (thrower.error()) return;
+  auto exports = i::wasm::GetExports(i_isolate, maybe_module.ToHandleChecked());
+  args.GetReturnValue().Set(Utils::ToLocal(exports));
 }
 
+// WebAssembly.Module.customSections(module, name) -> Array<Section>
 void WebAssemblyModuleCustomSections(
     const v8::FunctionCallbackInfo<v8::Value>& args) {
   HandleScope scope(args.GetIsolate());
   v8::Isolate* isolate = args.GetIsolate();
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
   ErrorThrower thrower(i_isolate, "WebAssembly.Module.customSections()");
 
   auto maybe_module = GetFirstArgumentAsModule(args, &thrower);
+  if (thrower.error()) return;
 
   if (args.Length() < 2) {
     thrower.TypeError("Argument 1 must be a string");
     return;
   }
 
   i::Handle<i::Object> name = Utils::OpenHandle(*args[1]);
   if (!name->IsString()) {
     thrower.TypeError("Argument 1 must be a string");
     return;
   }
 
-  if (!maybe_module.is_null()) {
-    auto custom_sections =
-        i::wasm::GetCustomSections(i_isolate, maybe_module.ToHandleChecked(),
-                                   i::Handle<i::String>::cast(name), &thrower);
-    if (!thrower.error()) {
-      args.GetReturnValue().Set(Utils::ToLocal(custom_sections));
-    }
-  }
+  auto custom_sections =
+      i::wasm::GetCustomSections(i_isolate, maybe_module.ToHandleChecked(),
+                                 i::Handle<i::String>::cast(name), &thrower);
+  if (thrower.error()) return;
+  args.GetReturnValue().Set(Utils::ToLocal(custom_sections));
 }
 
+// new WebAssembly.Instance(module, imports) -> WebAssembly.Instance
 void WebAssemblyInstance(const v8::FunctionCallbackInfo<v8::Value>& args) {
   HandleScope scope(args.GetIsolate());
   v8::Isolate* isolate = args.GetIsolate();
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
   ErrorThrower thrower(i_isolate, "WebAssembly.Instance()");
 
   auto maybe_module = GetFirstArgumentAsModule(args, &thrower);
+  if (thrower.error()) return;
 
-  if (!maybe_module.is_null()) {
-    MaybeLocal<Value> instance = InstantiateModuleImpl(
-        i_isolate, maybe_module.ToHandleChecked(), args, &thrower);
+  auto maybe_imports = GetSecondArgumentAsImports(args, &thrower);
+  if (thrower.error()) return;
 
-    if (instance.IsEmpty()) {
-      DCHECK(thrower.error());
-      return;
-    }
-    args.GetReturnValue().Set(instance.ToLocalChecked());
-  }
+  i::MaybeHandle<i::Object> instance_object = i::wasm::SyncInstantiate(
+      i_isolate, &thrower, maybe_module.ToHandleChecked(), maybe_imports,
+      i::MaybeHandle<i::JSArrayBuffer>());
+  if (instance_object.is_null()) return;
+  args.GetReturnValue().Set(Utils::ToLocal(instance_object.ToHandleChecked()));
 }
 
+// WebAssembly.instantiate(module, imports) -> WebAssembly.Instance
+// WebAssembly.instantiate(bytes, imports) ->
+//     {module: WebAssembly.Module, instance: WebAssembly.Instance}
 void WebAssemblyInstantiate(const v8::FunctionCallbackInfo<v8::Value>& args) {
   v8::Isolate* isolate = args.GetIsolate();
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
   ErrorThrower thrower(i_isolate, "WebAssembly.instantiate()");
 
   HandleScope scope(isolate);
 
   Local<Context> context = isolate->GetCurrentContext();
   i::Handle<i::Context> i_context = Utils::OpenHandle(*context);
 
@@ skipping 10 matching lines @@
     return;
   }
 
   i::Handle<i::Object> first_arg = Utils::OpenHandle(*args[0]);
   if (!first_arg->IsJSObject()) {
     thrower.TypeError(
         "Argument 0 must be a buffer source or a WebAssembly.Module object");
     resolver->Reject(context, Utils::ToLocal(thrower.Reify()));
     return;
   }
-  bool want_pair =
-      !HasBrand(first_arg, i::Handle<i::Symbol>(i_context->wasm_module_sym()));
-  i::Handle<i::WasmModuleObject> module_obj;
-  if (want_pair) {
-    i::MaybeHandle<i::WasmModuleObject> maybe_module_obj =
-        CreateModuleObject(isolate, args[0], &thrower);
-    if (!maybe_module_obj.ToHandle(&module_obj)) {
-      DCHECK(thrower.error());
+
+  auto maybe_imports = GetSecondArgumentAsImports(args, &thrower);
+  if (thrower.error()) {
+    resolver->Reject(context, Utils::ToLocal(thrower.Reify()));
+    return;
+  }
+  i::Handle<i::JSPromise> promise = Utils::OpenHandle(*resolver->GetPromise());
+
+  if (HasBrand(first_arg, i::Handle<i::Symbol>(i_context->wasm_module_sym()))) {
+    // WebAssembly.instantiate(module, imports) -> WebAssembly.Instance
+    auto module_object = GetFirstArgumentAsModule(args, &thrower);
+    i::wasm::AsyncInstantiate(i_isolate, promise,
+                              module_object.ToHandleChecked(), maybe_imports);
+  } else {
+    // WebAssembly.instantiate(bytes, imports) -> {module, instance}
+    auto bytes = GetFirstArgumentAsBytes(args, &thrower);
+    if (thrower.error()) {
       resolver->Reject(context, Utils::ToLocal(thrower.Reify()));
       return;
     }
-  } else {
-    module_obj = i::Handle<i::WasmModuleObject>::cast(first_arg);
-  }
-  DCHECK(!module_obj.is_null());
-  MaybeLocal<Value> instance =
-      InstantiateModuleImpl(i_isolate, module_obj, args, &thrower);
-  if (instance.IsEmpty()) {
-    DCHECK(thrower.error());
-    resolver->Reject(context, Utils::ToLocal(thrower.Reify()));
-  } else {
-    DCHECK(!thrower.error());
-    Local<Value> retval;
-    if (want_pair) {
-      i::Handle<i::JSFunction> object_function = i::Handle<i::JSFunction>(
-          i_isolate->native_context()->object_function(), i_isolate);
-
-      i::Handle<i::JSObject> i_retval =
-          i_isolate->factory()->NewJSObject(object_function, i::TENURED);
-      i::Handle<i::String> module_property_name =
-          i_isolate->factory()->InternalizeUtf8String("module");
-      i::Handle<i::String> instance_property_name =
-          i_isolate->factory()->InternalizeUtf8String("instance");
-      i::JSObject::AddProperty(i_retval, module_property_name, module_obj,
-                               i::NONE);
-      i::JSObject::AddProperty(i_retval, instance_property_name,
-                               Utils::OpenHandle(*instance.ToLocalChecked()),
-                               i::NONE);
-      retval = Utils::ToLocal(i_retval);
-    } else {
-      retval = instance.ToLocalChecked();
-    }
-    DCHECK(!retval.IsEmpty());
-    resolver->Resolve(context, retval);
+    i::wasm::AsyncCompileAndInstantiate(i_isolate, promise, bytes,
+                                        maybe_imports);
   }
 }
 
 bool GetIntegerProperty(v8::Isolate* isolate, ErrorThrower* thrower,
                         Local<Context> context, Local<v8::Object> object,
                         Local<String> property, int* result,
                         int64_t lower_bound, uint64_t upper_bound) {
   v8::MaybeLocal<v8::Value> maybe = object->Get(context, property);
   v8::Local<v8::Value> value;
   if (maybe.ToLocal(&value)) {
@@ skipping 10 matching lines @@
                           " is above the upper bound %" PRIu64,
                           number, upper_bound);
       return false;
     }
     *result = static_cast<int>(number);
     return true;
   }
   return false;
 }
 
+// new WebAssembly.Table(args) -> WebAssembly.Table
 void WebAssemblyTable(const v8::FunctionCallbackInfo<v8::Value>& args) {
   v8::Isolate* isolate = args.GetIsolate();
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
   HandleScope scope(isolate);
-  ErrorThrower thrower(reinterpret_cast<i::Isolate*>(isolate),
-                       "WebAssembly.Module()");
+  ErrorThrower thrower(i_isolate, "WebAssembly.Module()");
   if (args.Length() < 1 || !args[0]->IsObject()) {
     thrower.TypeError("Argument 0 must be a table descriptor");
     return;
   }
   Local<Context> context = isolate->GetCurrentContext();
   Local<v8::Object> descriptor = args[0]->ToObject(context).ToLocalChecked();
   // The descriptor's 'element'.
   {
     v8::MaybeLocal<v8::Value> maybe =
         descriptor->Get(context, v8_str(isolate, "element"));
@@ skipping 21 matching lines @@
   Maybe<bool> has_maximum = descriptor->Has(context, maximum_key);
 
   if (!has_maximum.IsNothing() && has_maximum.FromJust()) {
     if (!GetIntegerProperty(isolate, &thrower, context, descriptor, maximum_key,
                             &maximum, initial,
                             i::wasm::kSpecMaxWasmTableSize)) {
       return;
     }
   }
 
-  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
   i::Handle<i::FixedArray> fixed_array;
   i::Handle<i::JSObject> table_obj =
       i::WasmTableObject::New(i_isolate, initial, maximum, &fixed_array);
   v8::ReturnValue<v8::Value> return_value = args.GetReturnValue();
   return_value.Set(Utils::ToLocal(table_obj));
 }
 
 void WebAssemblyMemory(const v8::FunctionCallbackInfo<v8::Value>& args) {
   v8::Isolate* isolate = args.GetIsolate();
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
   HandleScope scope(isolate);
-  ErrorThrower thrower(reinterpret_cast<i::Isolate*>(isolate),
-                       "WebAssembly.Memory()");
+  ErrorThrower thrower(i_isolate, "WebAssembly.Memory()");
   if (args.Length() < 1 || !args[0]->IsObject()) {
     thrower.TypeError("Argument 0 must be a memory descriptor");
     return;
   }
   Local<Context> context = isolate->GetCurrentContext();
   Local<v8::Object> descriptor = args[0]->ToObject(context).ToLocalChecked();
   // The descriptor's 'initial'.
   int initial = 0;
   if (!GetIntegerProperty(isolate, &thrower, context, descriptor,
                           v8_str(isolate, "initial"), &initial, 0,
                           i::FLAG_wasm_max_mem_pages)) {
     return;
   }
   // The descriptor's 'maximum'.
   int maximum = -1;
   Local<String> maximum_key = v8_str(isolate, "maximum");
   Maybe<bool> has_maximum = descriptor->Has(context, maximum_key);
 
   if (!has_maximum.IsNothing() && has_maximum.FromJust()) {
     if (!GetIntegerProperty(isolate, &thrower, context, descriptor, maximum_key,
                             &maximum, initial,
                             i::wasm::kSpecMaxWasmMemoryPages)) {
       return;
     }
   }
-  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
   size_t size = static_cast<size_t>(i::wasm::WasmModule::kPageSize) *
                 static_cast<size_t>(initial);
   i::Handle<i::JSArrayBuffer> buffer =
       i::wasm::NewArrayBuffer(i_isolate, size, i::FLAG_wasm_guard_pages);
   if (buffer.is_null()) {
     thrower.RangeError("could not allocate memory");
     return;
   }
   i::Handle<i::JSObject> memory_obj =
       i::WasmMemoryObject::New(i_isolate, buffer, maximum);
   args.GetReturnValue().Set(Utils::ToLocal(memory_obj));
 }
 
 void WebAssemblyTableGetLength(
     const v8::FunctionCallbackInfo<v8::Value>& args) {
   v8::Isolate* isolate = args.GetIsolate();
-  ErrorThrower thrower(reinterpret_cast<i::Isolate*>(isolate),
-                       "WebAssembly.Table.length()");
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  HandleScope scope(isolate);
+  ErrorThrower thrower(i_isolate, "WebAssembly.Table.length()");
   Local<Context> context = isolate->GetCurrentContext();
   i::Handle<i::Context> i_context = Utils::OpenHandle(*context);
-  if (!BrandCheck(&thrower, Utils::OpenHandle(*args.This()),
-                  i::Handle<i::Symbol>(i_context->wasm_table_sym()),
+  if (!BrandCheck(Utils::OpenHandle(*args.This()),
+                  i::Handle<i::Symbol>(i_context->wasm_table_sym()), &thrower,
                   "Receiver is not a WebAssembly.Table")) {
     return;
   }
   auto receiver =
       i::Handle<i::WasmTableObject>::cast(Utils::OpenHandle(*args.This()));
   args.GetReturnValue().Set(
       v8::Number::New(isolate, receiver->current_length()));
 }
 
+// WebAssembly.Table.grow(num) -> num
 void WebAssemblyTableGrow(const v8::FunctionCallbackInfo<v8::Value>& args) {
   v8::Isolate* isolate = args.GetIsolate();
-  ErrorThrower thrower(reinterpret_cast<i::Isolate*>(isolate),
-                       "WebAssembly.Table.grow()");
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  HandleScope scope(isolate);
+  ErrorThrower thrower(i_isolate, "WebAssembly.Table.grow()");
   Local<Context> context = isolate->GetCurrentContext();
   i::Handle<i::Context> i_context = Utils::OpenHandle(*context);
-  if (!BrandCheck(&thrower, Utils::OpenHandle(*args.This()),
-                  i::Handle<i::Symbol>(i_context->wasm_table_sym()),
+  if (!BrandCheck(Utils::OpenHandle(*args.This()),
+                  i::Handle<i::Symbol>(i_context->wasm_table_sym()), &thrower,
                   "Receiver is not a WebAssembly.Table")) {
     return;
   }
 
-  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
   auto receiver =
       i::Handle<i::WasmTableObject>::cast(Utils::OpenHandle(*args.This()));
   i::Handle<i::FixedArray> old_array(receiver->functions(), i_isolate);
   int old_size = old_array->length();
   int64_t new_size64 = 0;
   if (args.Length() > 0 && !args[0]->IntegerValue(context).To(&new_size64)) {
     return;
   }
   new_size64 += old_size;
 
@@ skipping 20 matching lines @@
     i::Object* null = i_isolate->heap()->null_value();
     for (int i = old_size; i < new_size; ++i) new_array->set(i, null);
     receiver->set_functions(*new_array);
   }
 
   // TODO(gdeepti): use weak links for instances
   v8::ReturnValue<v8::Value> return_value = args.GetReturnValue();
   return_value.Set(old_size);
 }
 
+// WebAssembly.Table.get(num) -> JSFunction
 void WebAssemblyTableGet(const v8::FunctionCallbackInfo<v8::Value>& args) {
   v8::Isolate* isolate = args.GetIsolate();
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  HandleScope scope(isolate);
   ErrorThrower thrower(i_isolate, "WebAssembly.Table.get()");
   Local<Context> context = isolate->GetCurrentContext();
   i::Handle<i::Context> i_context = Utils::OpenHandle(*context);
-  if (!BrandCheck(&thrower, Utils::OpenHandle(*args.This()),
-                  i::Handle<i::Symbol>(i_context->wasm_table_sym()),
+  if (!BrandCheck(Utils::OpenHandle(*args.This()),
+                  i::Handle<i::Symbol>(i_context->wasm_table_sym()), &thrower,
                   "Receiver is not a WebAssembly.Table")) {
     return;
   }
 
   auto receiver =
       i::Handle<i::WasmTableObject>::cast(Utils::OpenHandle(*args.This()));
   i::Handle<i::FixedArray> array(receiver->functions(), i_isolate);
   int i = 0;
   if (args.Length() > 0 && !args[0]->Int32Value(context).To(&i)) return;
   v8::ReturnValue<v8::Value> return_value = args.GetReturnValue();
   if (i < 0 || i >= array->length()) {
     thrower.RangeError("index out of bounds");
     return;
   }
 
   i::Handle<i::Object> value(array->get(i), i_isolate);
   return_value.Set(Utils::ToLocal(value));
 }
 
+// WebAssembly.Table.set(num, JSFunction)
 void WebAssemblyTableSet(const v8::FunctionCallbackInfo<v8::Value>& args) {
   v8::Isolate* isolate = args.GetIsolate();
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  HandleScope scope(isolate);
   ErrorThrower thrower(i_isolate, "WebAssembly.Table.set()");
   Local<Context> context = isolate->GetCurrentContext();
   i::Handle<i::Context> i_context = Utils::OpenHandle(*context);
-  if (!BrandCheck(&thrower, Utils::OpenHandle(*args.This()),
-                  i::Handle<i::Symbol>(i_context->wasm_table_sym()),
+  if (!BrandCheck(Utils::OpenHandle(*args.This()),
+                  i::Handle<i::Symbol>(i_context->wasm_table_sym()), &thrower,
                   "Receiver is not a WebAssembly.Table")) {
     return;
   }
   if (args.Length() < 2) {
     thrower.TypeError("Argument 1 must be null or a function");
     return;
   }
   i::Handle<i::Object> value = Utils::OpenHandle(*args[1]);
   if (!value->IsNull(i_isolate) &&
       (!value->IsJSFunction() ||
@@ skipping 19 matching lines @@
     i::wasm::UpdateDispatchTables(i_isolate, dispatch_tables, i,
                                   i::Handle<i::JSFunction>::null());
   } else {
     i::wasm::UpdateDispatchTables(i_isolate, dispatch_tables, i,
                                   i::Handle<i::JSFunction>::cast(value));
   }
 
   i::Handle<i::FixedArray>::cast(array)->set(i, *value);
 }
 
+// WebAssembly.Memory.grow(num) -> num
 void WebAssemblyMemoryGrow(const v8::FunctionCallbackInfo<v8::Value>& args) {
   v8::Isolate* isolate = args.GetIsolate();
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  HandleScope scope(isolate);
   ErrorThrower thrower(i_isolate, "WebAssembly.Memory.grow()");
   Local<Context> context = isolate->GetCurrentContext();
   i::Handle<i::Context> i_context = Utils::OpenHandle(*context);
-  if (!BrandCheck(&thrower, Utils::OpenHandle(*args.This()),
-                  i::Handle<i::Symbol>(i_context->wasm_memory_sym()),
+  if (!BrandCheck(Utils::OpenHandle(*args.This()),
+                  i::Handle<i::Symbol>(i_context->wasm_memory_sym()), &thrower,
                   "Receiver is not a WebAssembly.Memory")) {
     return;
   }
   int64_t delta_size = 0;
   if (args.Length() < 1 || !args[0]->IntegerValue(context).To(&delta_size)) {
     thrower.TypeError("Argument 0 required, must be numeric value of pages");
     return;
   }
   i::Handle<i::WasmMemoryObject> receiver =
       i::Handle<i::WasmMemoryObject>::cast(Utils::OpenHandle(*args.This()));
@@ skipping 14 matching lines @@
   int32_t ret = i::wasm::GrowWebAssemblyMemory(
       i_isolate, receiver, static_cast<uint32_t>(delta_size));
   if (ret == -1) {
     thrower.RangeError("Unable to grow instance memory.");
     return;
   }
   v8::ReturnValue<v8::Value> return_value = args.GetReturnValue();
   return_value.Set(ret);
 }
 
+// WebAssembly.Memory.buffer -> ArrayBuffer
 void WebAssemblyMemoryGetBuffer(
     const v8::FunctionCallbackInfo<v8::Value>& args) {
   v8::Isolate* isolate = args.GetIsolate();
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  HandleScope scope(isolate);
   ErrorThrower thrower(i_isolate, "WebAssembly.Memory.buffer");
   Local<Context> context = isolate->GetCurrentContext();
   i::Handle<i::Context> i_context = Utils::OpenHandle(*context);
-  if (!BrandCheck(&thrower, Utils::OpenHandle(*args.This()),
-                  i::Handle<i::Symbol>(i_context->wasm_memory_sym()),
+  if (!BrandCheck(Utils::OpenHandle(*args.This()),
+                  i::Handle<i::Symbol>(i_context->wasm_memory_sym()), &thrower,
                   "Receiver is not a WebAssembly.Memory")) {
     return;
   }
   i::Handle<i::WasmMemoryObject> receiver =
       i::Handle<i::WasmMemoryObject>::cast(Utils::OpenHandle(*args.This()));
   i::Handle<i::Object> buffer(receiver->buffer(), i_isolate);
   DCHECK(buffer->IsJSArrayBuffer());
   v8::ReturnValue<v8::Value> return_value = args.GetReturnValue();
   return_value.Set(Utils::ToLocal(buffer));
 }
@@ skipping 198 matching lines @@
   i::Handle<i::Symbol> symbol(isolate->context()->wasm_memory_sym(), isolate);
   return HasBrand(value, symbol);
 }
 
 bool WasmJs::IsWasmTableObject(Isolate* isolate, Handle<Object> value) {
   i::Handle<i::Symbol> symbol(isolate->context()->wasm_table_sym(), isolate);
   return HasBrand(value, symbol);
 }
 }  // namespace internal
 }  // namespace v8