[wasm] instantiate expressed in terms of compile

src/wasm/wasm-js.cc

Index: src/wasm/wasm-js.cc
diff --git a/src/wasm/wasm-js.cc b/src/wasm/wasm-js.cc
index 3b275d19ecccc1444274f0fe60f93fe177d40dbb..93b396ba9a0365c8e9b803d26581cbbd7b2b1729 100644
--- a/src/wasm/wasm-js.cc
+++ b/src/wasm/wasm-js.cc
@@ -32,6 +32,14 @@ namespace v8 {
 
 namespace {
 
+#define ASSIGN(type, var, expr)                   \
+  Local<type> var;                                \
+  do {                                            \
+    if (!expr.ToLocal(&var)) {                    \
+      DCHECK(i_isolate->has_pending_exception()); \

[adamk, 2017/04/18 17:17:22]

You still need to return here, otherwise we'll crash due to the empty var
farther down in the function.

+    }                                             \
+  } while (false)
+
 // 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) {
@@ -117,16 +125,15 @@ i::wasm::ModuleWireBytes GetFirstArgumentAsBytes(
   return i::wasm::ModuleWireBytes(start, start + length);
 }
 
-i::MaybeHandle<i::JSReceiver> GetSecondArgumentAsImports(
-    const v8::FunctionCallbackInfo<v8::Value>& args, ErrorThrower* thrower) {
-  if (args.Length() < 2) return {};
-  if (args[1]->IsUndefined()) return {};
+i::MaybeHandle<i::JSReceiver> GetValueAsImports(const Local<Value>& arg,

[adamk, 2017/04/18 17:17:22]

Style nit: we pass Locals and Handles by value (they're just pointers)

+                                                ErrorThrower* thrower) {
+  if (arg->IsUndefined()) return {};
 
-  if (!args[1]->IsObject()) {
+  if (!arg->IsObject()) {
     thrower->TypeError("Argument 1 must be an object");
     return {};
   }
-  Local<Object> obj = Local<Object>::Cast(args[1]);
+  Local<Object> obj = Local<Object>::Cast(arg);
   return i::Handle<i::JSReceiver>::cast(v8::Utils::OpenHandle(*obj));
 }
 
@@ -134,14 +141,14 @@ i::MaybeHandle<i::JSReceiver> GetSecondArgumentAsImports(
 void WebAssemblyCompile(const v8::FunctionCallbackInfo<v8::Value>& args) {
   v8::Isolate* isolate = args.GetIsolate();
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  MicrotasksScope runs_microtasks(isolate, MicrotasksScope::kRunMicrotasks);
   if (i_isolate->wasm_compile_callback()(args)) return;
 
   HandleScope scope(isolate);
   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;
+  ASSIGN(Promise::Resolver, resolver, Promise::Resolver::New(context));
   v8::ReturnValue<v8::Value> return_value = args.GetReturnValue();
   return_value.Set(resolver->GetPromise());
 
@@ -253,10 +260,90 @@ void WebAssemblyModuleCustomSections(
   args.GetReturnValue().Set(Utils::ToLocal(custom_sections));
 }
 
+MaybeLocal<Value> WebAssemblyInstantiateImpl(Isolate* isolate,
+                                             Local<Value> module,
+                                             Local<Value> ffi) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+
+  ErrorThrower thrower(i_isolate, "WebAssembly Instantiation");
+  i::MaybeHandle<i::JSReceiver> maybe_imports =
+      GetValueAsImports(ffi, &thrower);
+  if (thrower.error()) return {};
+
+  i::Handle<i::WasmModuleObject> module_obj =
+      i::Handle<i::WasmModuleObject>::cast(
+          Utils::OpenHandle(Object::Cast(*module)));
+  i::MaybeHandle<i::Object> instance_object =
+      i::wasm::SyncInstantiate(i_isolate, &thrower, module_obj, maybe_imports,
+                               i::MaybeHandle<i::JSArrayBuffer>());
+
+  if (instance_object.is_null()) {
+    // TODO(wasm): this *should* mean there's an error to throw, but
+    // we exit sometimes the instantiation pipeline without throwing.
+    // v8:6232.
+    return {};
+  }
+  return Utils::ToLocal(instance_object.ToHandleChecked());
+}
+
+// Entered as internal implementation detail of sync and async instantiate.
+// args[0] *must* be a WebAssembly.Module.
+void WebAssemblyInstantiateImplCallback(
+    const v8::FunctionCallbackInfo<v8::Value>& args) {
+  DCHECK_GE(args.Length(), 1);
+  v8::Isolate* isolate = args.GetIsolate();
+  MicrotasksScope does_not_run_microtasks(isolate,
+                                          MicrotasksScope::kDoNotRunMicrotasks);
+
+  HandleScope scope(args.GetIsolate());
+  Local<Value> module = args[0];
+  Local<Value> ffi = args.Data();
+  Local<Value> instance;
+  if (WebAssemblyInstantiateImpl(isolate, module, ffi).ToLocal(&instance)) {
+    args.GetReturnValue().Set(instance);
+  }
+}
+
+void WebAssemblyInstantiateToPairCallback(
+    const v8::FunctionCallbackInfo<v8::Value>& args) {
+  DCHECK_GE(args.Length(), 1);
+  Isolate* isolate = args.GetIsolate();
+  MicrotasksScope does_not_run_microtasks(isolate,
+                                          MicrotasksScope::kDoNotRunMicrotasks);
+
+  HandleScope scope(args.GetIsolate());
+
+  Local<Context> context = isolate->GetCurrentContext();
+  Local<Value> module = args[0];
+
+  const uint8_t* instance_str = reinterpret_cast<const uint8_t*>("instance");
+  const uint8_t* module_str = reinterpret_cast<const uint8_t*>("module");
+  Local<Value> instance;
+  if (!WebAssemblyInstantiateImpl(isolate, module, args.Data())
+           .ToLocal(&instance))

[adamk, 2017/04/18 17:17:22]

Style nit: please add { } around if-statement body if it doesn't all fit on one
line.

+    return;
+
+  Local<Object> ret = Object::New(isolate);
+  Local<String> instance_name =
+      String::NewFromOneByte(isolate, instance_str,
+                             NewStringType::kInternalized)
+          .ToLocalChecked();
+  Local<String> module_name =
+      String::NewFromOneByte(isolate, module_str, NewStringType::kInternalized)
+          .ToLocalChecked();
+
+  CHECK(ret->CreateDataProperty(context, instance_name, instance).IsJust());
+  CHECK(ret->CreateDataProperty(context, module_name, module).IsJust());
+  args.GetReturnValue().Set(ret);
+}
+
 // new WebAssembly.Instance(module, imports) -> WebAssembly.Instance
 void WebAssemblyInstance(const v8::FunctionCallbackInfo<v8::Value>& args) {
+  Isolate* isolate = args.GetIsolate();
+  MicrotasksScope does_not_run_microtasks(isolate,
+                                          MicrotasksScope::kDoNotRunMicrotasks);
+
   HandleScope scope(args.GetIsolate());
-  v8::Isolate* isolate = args.GetIsolate();
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
   if (i_isolate->wasm_instance_callback()(args)) return;
 
@@ -265,14 +352,14 @@ void WebAssemblyInstance(const v8::FunctionCallbackInfo<v8::Value>& args) {
   auto maybe_module = GetFirstArgumentAsModule(args, &thrower);
   if (thrower.error()) return;
 
-  auto maybe_imports = GetSecondArgumentAsImports(args, &thrower);
-  if (thrower.error()) return;
+  // If args.Length < 2, this will be undefined - see FunctionCallbackInfo.
+  // We'll check for that in WebAssemblyInstantiateImpl.
+  Local<Value> data = args[1];
 
-  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()));
+  Local<Value> instance;
+  if (WebAssemblyInstantiateImpl(isolate, args[0], data).ToLocal(&instance)) {
+    args.GetReturnValue().Set(instance);
+  }
 }
 
 // WebAssembly.instantiate(module, imports) -> WebAssembly.Instance
@@ -281,6 +368,7 @@ void WebAssemblyInstance(const v8::FunctionCallbackInfo<v8::Value>& args) {
 void WebAssemblyInstantiate(const v8::FunctionCallbackInfo<v8::Value>& args) {
   v8::Isolate* isolate = args.GetIsolate();
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  MicrotasksScope runs_microtasks(isolate, MicrotasksScope::kRunMicrotasks);
   if (i_isolate->wasm_instantiate_callback()(args)) return;
 
   ErrorThrower thrower(i_isolate, "WebAssembly.instantiate()");
@@ -290,10 +378,9 @@ void WebAssemblyInstantiate(const v8::FunctionCallbackInfo<v8::Value>& args) {
   Local<Context> context = isolate->GetCurrentContext();
   i::Handle<i::Context> i_context = Utils::OpenHandle(*context);
 
-  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());
+  ASSIGN(Promise::Resolver, resolver, Promise::Resolver::New(context));
+  Local<Promise> module_promise = resolver->GetPromise();
+  args.GetReturnValue().Set(module_promise);
 
   if (args.Length() < 1) {
     thrower.TypeError(
@@ -305,7 +392,8 @@ void WebAssemblyInstantiate(const v8::FunctionCallbackInfo<v8::Value>& args) {
     return;
   }
 
-  i::Handle<i::Object> first_arg = Utils::OpenHandle(*args[0]);
+  Local<Value> first_arg_value = args[0];
+  i::Handle<i::Object> first_arg = Utils::OpenHandle(*first_arg_value);
   if (!first_arg->IsJSObject()) {
     thrower.TypeError(
         "Argument 0 must be a buffer source or a WebAssembly.Module object");
@@ -315,31 +403,27 @@ void WebAssemblyInstantiate(const v8::FunctionCallbackInfo<v8::Value>& args) {
     return;
   }
 
-  auto maybe_imports = GetSecondArgumentAsImports(args, &thrower);
-  if (thrower.error()) {
-    auto maybe = resolver->Reject(context, Utils::ToLocal(thrower.Reify()));
-    CHECK_IMPLIES(!maybe.FromMaybe(false),
-                  i_isolate->has_scheduled_exception());
-    return;
-  }
-  i::Handle<i::JSPromise> promise = Utils::OpenHandle(*resolver->GetPromise());
+  FunctionCallback instantiator = nullptr;
   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);
+    module_promise = resolver->GetPromise();
+    if (!resolver->Resolve(context, first_arg_value).IsJust()) return;
+    instantiator = WebAssemblyInstantiateImplCallback;
   } else {
-    // WebAssembly.instantiate(bytes, imports) -> {module, instance}
-    auto bytes = GetFirstArgumentAsBytes(args, &thrower);
-    if (thrower.error()) {
-      auto maybe = resolver->Reject(context, Utils::ToLocal(thrower.Reify()));
-      CHECK_IMPLIES(!maybe.FromMaybe(false),
-                    i_isolate->has_scheduled_exception());
-      return;
-    }
-    i::wasm::AsyncCompileAndInstantiate(i_isolate, promise, bytes,
-                                        maybe_imports);
-  }
+    ASSIGN(Function, async_compile, Function::New(context, WebAssemblyCompile));
+    ASSIGN(Value, async_compile_retval,
+           async_compile->Call(context, args.Holder(), 1, &first_arg_value));
+    module_promise = Local<Promise>::Cast(async_compile_retval);
+    instantiator = WebAssemblyInstantiateToPairCallback;
+  }
+  DCHECK(!module_promise.IsEmpty());
+  DCHECK_NOT_NULL(instantiator);
+  // If args.Length < 2, this will be undefined - see FunctionCallbackInfo.
+  // We'll check for that in WebAssemblyInstantiateImpl.
+  Local<Value> data = args[1];
+  ASSIGN(Function, instantiate_impl,
+         Function::New(context, instantiator, data));
+  ASSIGN(Promise, result, module_promise->Then(context, instantiate_impl));
+  args.GetReturnValue().Set(result);
 }
 
 bool GetIntegerProperty(v8::Isolate* isolate, ErrorThrower* thrower,