Ensure slow properties for simple {__proto__:null} literals.

src/ast/ast.h

 // Copyright 2012 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.
 
 #ifndef V8_AST_AST_H_
 #define V8_AST_AST_H_
 
 #include "src/ast/ast-types.h"
 #include "src/ast/ast-value-factory.h"
 #include "src/ast/modules.h"
@@ skipping 1335 matching lines @@
   bool IsMonomorphic() const { return !receiver_type_.is_null(); }
   Handle<Map> GetReceiverType() const { return receiver_type_; }
 
   bool IsCompileTimeValue() const;
 
   void set_emit_store(bool emit_store);
   bool emit_store() const;
 
   void set_receiver_type(Handle<Map> map) { receiver_type_ = map; }
 
+  bool IsNullPrototype() const {
+    if (!IsPrototype()) return false;
+    return value()->IsNullLiteral();

[adamk, 2017/03/13 18:10:44]

Nit:

return IsPrototype() && value()->IsNullLiteral()

seems just as clear to me.

[Camillo Bruni, 2017/03/17 16:40:55]

uhm, right, used to be more complex ;)

+  }
+  bool IsPrototype() const { return kind() == PROTOTYPE; }
+
  private:
   friend class AstNodeFactory;
 
   ObjectLiteralProperty(Expression* key, Expression* value, Kind kind,
                         bool is_computed_name);
   ObjectLiteralProperty(AstValueFactory* ast_value_factory, Expression* key,
                         Expression* value, bool is_computed_name);
 
   Kind kind_;
   bool emit_store_;
@@ skipping 17 matching lines @@
   bool may_store_doubles() const {
     return MayStoreDoublesField::decode(bit_field_);
   }
   bool has_elements() const { return HasElementsField::decode(bit_field_); }
   bool has_shallow_properties() const {
     return depth() == 1 && !has_elements() && !may_store_doubles();
   }
   bool has_rest_property() const {
     return HasRestPropertyField::decode(bit_field_);
   }
-
+  bool HasNullPrototype() const {
+    for (int i = 0; i < properties()->length(); i++) {
+      const ObjectLiteral::Property* property = properties()->at(i);
+      if (property->IsNullPrototype()) return true;
+    }
+    return false;
+  }
   // Decide if a property should be in the object boilerplate.
   static bool IsBoilerplateProperty(Property* property);
 
   // Populate the depth field and flags.
   void InitDepthAndFlags();
 
   // Get the constant properties fixed array, populating it if necessary.
   Handle<BoilerplateDescription> GetOrBuildConstantProperties(
       Isolate* isolate) {
     if (constant_properties_.is_null()) {
       BuildConstantProperties(isolate);
     }
     return constant_properties();
   }
 
   // Populate the constant properties fixed array.
   void BuildConstantProperties(Isolate* isolate);
 
   // Mark all computed expressions that are bound to a key that
   // is shadowed by a later occurrence of the same key. For the
   // marked expressions, no store code is emitted.
   void CalculateEmitStore(Zone* zone);
 
   // Determines whether the {FastCloneShallowObject} builtin can be used.
   bool IsFastCloningSupported() const;
 
   // Assemble bitfield of flags for the CreateObjectLiteral helper.
   int ComputeFlags(bool disable_mementos = false) const {
     int flags = fast_elements() ? kFastElements : kNoFlags;
-    if (has_shallow_properties()) {
-      flags |= kShallowProperties;
-    }
-    if (disable_mementos) {
-      flags |= kDisableMementos;
-    }
+    if (HasNullPrototype()) flags |= kHasNullPrototype;
+    if (has_shallow_properties()) flags |= kShallowProperties;
+    if (disable_mementos) flags |= kDisableMementos;
     return flags;
   }
 
   enum Flags {
     kNoFlags = 0,
     kFastElements = 1,
     kShallowProperties = 1 << 1,
     kDisableMementos = 1 << 2,
     kHasRestProperty = 1 << 3,
+    kHasNullPrototype = 1 << 4,
   };
 
   struct Accessors: public ZoneObject {
     Accessors() : getter(NULL), setter(NULL), bailout_id(BailoutId::None()) {}
     ObjectLiteralProperty* getter;
     ObjectLiteralProperty* setter;
     BailoutId bailout_id;
   };
 
   BailoutId CreateLiteralId() const { return BailoutId(local_id(0)); }
@@ skipping 2189 matching lines @@
                                     : NULL;                                   \
   }
 AST_NODE_LIST(DECLARE_NODE_FUNCTIONS)
 #undef DECLARE_NODE_FUNCTIONS
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_AST_AST_H_