[runtime] Introduce dedicated JSBoundFunction to represent bound functions.

src/bootstrapper.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/bootstrapper.h"
 
 #include "src/accessors.h"
 #include "src/api-natives.h"
 #include "src/code-stubs.h"
 #include "src/extensions/externalize-string-extension.h"
@@ skipping 251 matching lines @@
   // 'from'.
   void TransferObject(Handle<JSObject> from, Handle<JSObject> to);
   void TransferNamedProperties(Handle<JSObject> from, Handle<JSObject> to);
   void TransferIndexedProperties(Handle<JSObject> from, Handle<JSObject> to);
 
   enum FunctionMode {
     // With prototype.
     FUNCTION_WITH_WRITEABLE_PROTOTYPE,
     FUNCTION_WITH_READONLY_PROTOTYPE,
     // Without prototype.
-    FUNCTION_WITHOUT_PROTOTYPE,
-    BOUND_FUNCTION
+    FUNCTION_WITHOUT_PROTOTYPE
   };
 
   static bool IsFunctionModeWithPrototype(FunctionMode function_mode) {
     return (function_mode == FUNCTION_WITH_WRITEABLE_PROTOTYPE ||
             function_mode == FUNCTION_WITH_READONLY_PROTOTYPE);
   }
 
   Handle<Map> CreateSloppyFunctionMap(FunctionMode function_mode);
 
   void SetFunctionInstanceDescriptor(Handle<Map> map,
@@ skipping 195 matching lines @@
     AccessorConstantDescriptor d(Handle<Name>(Name::cast(prototype->name())),
                                  prototype, ro_attribs);
     map->AppendDescriptor(&d);
   }
 }
 
 
 Handle<Map> Genesis::CreateSloppyFunctionMap(FunctionMode function_mode) {
   Handle<Map> map = factory()->NewMap(JS_FUNCTION_TYPE, JSFunction::kSize);
   SetFunctionInstanceDescriptor(map, function_mode);
-  map->set_is_constructor(IsFunctionModeWithPrototype(function_mode));
+  if (IsFunctionModeWithPrototype(function_mode)) map->set_is_constructor();
   map->set_is_callable();
   return map;
 }
 
 
 Handle<JSFunction> Genesis::CreateEmptyFunction(Isolate* isolate) {
   // Allocate the map for function instances. Maps are allocated first and their
   // prototypes patched later, once empty function is created.
 
   // Functions with this map will not have a 'prototype' property, and
@@ skipping 102 matching lines @@
   int size = IsFunctionModeWithPrototype(function_mode) ? 3 : 2;
   Map::EnsureDescriptorSlack(map, size);
 
   PropertyAttributes rw_attribs =
       static_cast<PropertyAttributes>(DONT_ENUM | DONT_DELETE);
   PropertyAttributes ro_attribs =
       static_cast<PropertyAttributes>(DONT_ENUM | DONT_DELETE | READ_ONLY);
   PropertyAttributes roc_attribs =
       static_cast<PropertyAttributes>(DONT_ENUM | READ_ONLY);
 
-  if (function_mode == BOUND_FUNCTION) {
-    {  // Add length.
-      Handle<String> length_string = isolate()->factory()->length_string();
-      DataDescriptor d(length_string, 0, roc_attribs, Representation::Tagged());
-      map->AppendDescriptor(&d);
-    }
-    {  // Add name.
-      Handle<String> name_string = isolate()->factory()->name_string();
-      DataDescriptor d(name_string, 1, roc_attribs, Representation::Tagged());
-      map->AppendDescriptor(&d);
-    }
-  } else {
-    DCHECK(function_mode == FUNCTION_WITH_WRITEABLE_PROTOTYPE ||
-           function_mode == FUNCTION_WITH_READONLY_PROTOTYPE ||
-           function_mode == FUNCTION_WITHOUT_PROTOTYPE);
-    {  // Add length.
-      Handle<AccessorInfo> length =
-          Accessors::FunctionLengthInfo(isolate(), roc_attribs);
-      AccessorConstantDescriptor d(Handle<Name>(Name::cast(length->name())),
-                                   length, roc_attribs);
-      map->AppendDescriptor(&d);
-    }
-    {  // Add name.
-      Handle<AccessorInfo> name =
-          Accessors::FunctionNameInfo(isolate(), roc_attribs);
-      AccessorConstantDescriptor d(Handle<Name>(Name::cast(name->name())), name,
-                                   roc_attribs);
-      map->AppendDescriptor(&d);
-    }
+  DCHECK(function_mode == FUNCTION_WITH_WRITEABLE_PROTOTYPE ||
+         function_mode == FUNCTION_WITH_READONLY_PROTOTYPE ||
+         function_mode == FUNCTION_WITHOUT_PROTOTYPE);
+  {  // Add length.
+    Handle<AccessorInfo> length =
+        Accessors::FunctionLengthInfo(isolate(), roc_attribs);
+    AccessorConstantDescriptor d(Handle<Name>(Name::cast(length->name())),
+                                 length, roc_attribs);
+    map->AppendDescriptor(&d);
+  }
+  {  // Add name.
+    Handle<AccessorInfo> name =
+        Accessors::FunctionNameInfo(isolate(), roc_attribs);
+    AccessorConstantDescriptor d(Handle<Name>(Name::cast(name->name())), name,
+                                 roc_attribs);
+    map->AppendDescriptor(&d);
   }
   if (IsFunctionModeWithPrototype(function_mode)) {
     // Add prototype.
     PropertyAttributes attribs =
         function_mode == FUNCTION_WITH_WRITEABLE_PROTOTYPE ? rw_attribs
                                                            : ro_attribs;
     Handle<AccessorInfo> prototype =
         Accessors::FunctionPrototypeInfo(isolate(), attribs);
     AccessorConstantDescriptor d(Handle<Name>(Name::cast(prototype->name())),
                                  prototype, attribs);
@@ skipping 74 matching lines @@
         Builtins::kRestrictedStrictArgumentsPropertiesThrower);
   }
   return strict_poison_function_;
 }
 
 
 Handle<Map> Genesis::CreateStrictFunctionMap(
     FunctionMode function_mode, Handle<JSFunction> empty_function) {
   Handle<Map> map = factory()->NewMap(JS_FUNCTION_TYPE, JSFunction::kSize);
   SetStrictFunctionInstanceDescriptor(map, function_mode);
-  map->set_is_constructor(IsFunctionModeWithPrototype(function_mode));
+  if (IsFunctionModeWithPrototype(function_mode)) map->set_is_constructor();
   map->set_is_callable();
   Map::SetPrototype(map, empty_function);
   return map;
 }
 
 
 Handle<Map> Genesis::CreateStrongFunctionMap(
     Handle<JSFunction> empty_function, bool is_constructor) {
   Handle<Map> map = factory()->NewMap(JS_FUNCTION_TYPE, JSFunction::kSize);
   SetStrongFunctionInstanceDescriptor(map);
-  map->set_is_constructor(is_constructor);
+  if (is_constructor) map->set_is_constructor();
   Map::SetPrototype(map, empty_function);
   map->set_is_callable();
   map->set_is_extensible(is_constructor);
   map->set_is_strong();
   return map;
 }
 
 
 void Genesis::CreateStrictModeFunctionMaps(Handle<JSFunction> empty) {
   // Allocate map for the prototype-less strict mode instances.
   Handle<Map> strict_function_without_prototype_map =
       CreateStrictFunctionMap(FUNCTION_WITHOUT_PROTOTYPE, empty);
   native_context()->set_strict_function_without_prototype_map(
       *strict_function_without_prototype_map);
 
   // Allocate map for the strict mode functions. This map is temporary, used
   // only for processing of builtins.
   // Later the map is replaced with writable prototype map, allocated below.
   Handle<Map> strict_function_map =
       CreateStrictFunctionMap(FUNCTION_WITH_READONLY_PROTOTYPE, empty);
   native_context()->set_strict_function_map(*strict_function_map);
 
   // The final map for the strict mode functions. Writeable prototype.
   // This map is installed in MakeFunctionInstancePrototypeWritable.
   strict_function_map_writable_prototype_ =
       CreateStrictFunctionMap(FUNCTION_WITH_WRITEABLE_PROTOTYPE, empty);
-
-  // Special map for non-constructor bound functions.
-  // TODO(bmeurer): Bound functions should not be represented as JSFunctions.
-  Handle<Map> bound_function_without_constructor_map =
-      CreateStrictFunctionMap(BOUND_FUNCTION, empty);
-  native_context()->set_bound_function_without_constructor_map(
-      *bound_function_without_constructor_map);
-
-  // Special map for constructor bound functions.
-  // TODO(bmeurer): Bound functions should not be represented as JSFunctions.
-  Handle<Map> bound_function_with_constructor_map =
-      Map::Copy(bound_function_without_constructor_map, "IsConstructor");
-  bound_function_with_constructor_map->set_is_constructor(true);
-  native_context()->set_bound_function_with_constructor_map(
-      *bound_function_with_constructor_map);
 }
 
 
 void Genesis::CreateStrongModeFunctionMaps(Handle<JSFunction> empty) {
   // Allocate map for strong mode instances, which never have prototypes.
   Handle<Map> strong_function_map = CreateStrongFunctionMap(empty, false);
   native_context()->set_strong_function_map(*strong_function_map);
   // Constructors do, though.
   Handle<Map> strong_constructor_map = CreateStrongFunctionMap(empty, true);
   native_context()->set_strong_constructor_map(*strong_constructor_map);
@@ skipping 654 matching lines @@
   }
 
   {  // -- W e a k S e t
     Handle<JSFunction> js_weak_set_fun = InstallFunction(
         global, "WeakSet", JS_WEAK_SET_TYPE, JSWeakSet::kSize,
         isolate->initial_object_prototype(), Builtins::kIllegal);
     InstallWithIntrinsicDefaultProto(isolate, js_weak_set_fun,
                                      Context::JS_WEAK_SET_FUN_INDEX);
   }
 
+  {  // --- B o u n d F u n c t i o n
+    Handle<Map> map =
+        factory->NewMap(JS_BOUND_FUNCTION_TYPE, JSBoundFunction::kSize);
+    map->set_is_callable();
+    Map::SetPrototype(map, empty_function);
+
+    PropertyAttributes roc_attribs =
+        static_cast<PropertyAttributes>(DONT_ENUM | READ_ONLY);
+    Map::EnsureDescriptorSlack(map, 2);
+
+    {  // length
+      DataDescriptor d(factory->length_string(), JSBoundFunction::kLengthIndex,
+                       roc_attribs, Representation::Tagged());
+      map->AppendDescriptor(&d);
+    }
+    {  // name
+      DataDescriptor d(factory->name_string(), JSBoundFunction::kNameIndex,
+                       roc_attribs, Representation::Tagged());
+      map->AppendDescriptor(&d);
+    }
+
+    map->SetInObjectProperties(2);
+    native_context()->set_bound_function_without_constructor_map(*map);
+
+    map = Map::Copy(map, "IsConstructor");
+    map->set_is_constructor();
+    native_context()->set_bound_function_with_constructor_map(*map);
+  }
+
   {  // --- sloppy arguments map
     // Make sure we can recognize argument objects at runtime.
     // This is done by introducing an anonymous function with
     // class_name equals 'Arguments'.
     Handle<String> arguments_string = factory->Arguments_string();
     Handle<Code> code = isolate->builtins()->Illegal();
     Handle<JSFunction> function = factory->NewFunctionWithoutPrototype(
         arguments_string, code);
     function->shared()->set_instance_class_name(*arguments_string);
 
@@ skipping 806 matching lines @@
 }
 
 
 void Genesis::InstallJSProxyMaps() {
   // Allocate the different maps for all Proxy types.
   // Next to the default proxy, we need maps indicating callable and
   // constructable proxies.
 
   Handle<Map> proxy_function_map =
       Map::Copy(isolate()->sloppy_function_without_prototype_map(), "Proxy");
-  proxy_function_map->set_is_constructor(true);
+  proxy_function_map->set_is_constructor();
   native_context()->set_proxy_function_map(*proxy_function_map);
 
   Handle<Map> proxy_map =
       factory()->NewMap(JS_PROXY_TYPE, JSProxy::kSize, FAST_ELEMENTS);
   native_context()->set_proxy_map(*proxy_map);
 
   Handle<Map> proxy_callable_map = Map::Copy(proxy_map, "callable Proxy");
   proxy_callable_map->set_is_callable();
   native_context()->set_proxy_callable_map(*proxy_callable_map);
   proxy_callable_map->SetConstructor(native_context()->function_function());
 
   Handle<Map> proxy_constructor_map =
       Map::Copy(proxy_callable_map, "constructor Proxy");
-  proxy_constructor_map->set_is_constructor(true);
+  proxy_constructor_map->set_is_constructor();
   native_context()->set_proxy_constructor_map(*proxy_constructor_map);
 }
 
 
 void Genesis::InitializeGlobal_harmony_proxies() {
   if (!FLAG_harmony_proxies) return;
   Handle<JSGlobalObject> global(
       JSGlobalObject::cast(native_context()->global_object()));
   Isolate* isolate = global->GetIsolate();
   Factory* factory = isolate->factory();
@@ skipping 205 matching lines @@
                         MaybeHandle<JSObject>(), Builtins::kArrayConcat);
 
     // Make sure that InternalArray.prototype.concat appears to be compiled.
     // The code will never be called, but inline caching for call will
     // only work if it appears to be compiled.
     concat->shared()->DontAdaptArguments();
     DCHECK(concat->is_compiled());
     // Set the lengths for the functions to satisfy ECMA-262.
     concat->shared()->set_length(1);
   }
-  // Install Function.prototype.apply, call, and toString.
+
+  // Install Function.prototype.apply, bind, call, and toString.
   {
     Handle<String> key = factory()->Function_string();
     Handle<JSFunction> function =
         Handle<JSFunction>::cast(Object::GetProperty(
             handle(native_context()->global_object()), key).ToHandleChecked());
     Handle<JSObject> proto =
         Handle<JSObject>(JSObject::cast(function->instance_prototype()));
 
-    // Install the apply, call and toString functions.
+    // Install the apply, bind, call and toString functions.
     SimpleInstallFunction(proto, factory()->apply_string(),
                           Builtins::kFunctionPrototypeApply, 2, false);
+    SimpleInstallFunction(proto, factory()->bind_string(),
+                          Builtins::kFunctionPrototypeBind, 1, false);
     SimpleInstallFunction(proto, factory()->call_string(),
                           Builtins::kFunctionPrototypeCall, 1, false);
     SimpleInstallFunction(proto, factory()->toString_string(),
                           Builtins::kFunctionPrototypeToString, 0, false);
   }
 
   // Set up the Promise constructor.
   {
     Handle<String> key = factory()->Promise_string();
     Handle<JSFunction> function = Handle<JSFunction>::cast(
@@ skipping 803 matching lines @@
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   DCHECK(!IsActive());
 }
 
 }  // namespace internal
 }  // namespace v8