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

src/ast/ast.cc

 // 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.
 
 #include "src/ast/ast.h"
 
 #include <cmath>  // For isfinite.
 
 #include "src/ast/compile-time-value.h"
 #include "src/ast/prettyprinter.h"
@@ skipping 472 matching lines @@
           property->SetSlot(spec->AddStoreICSlot(language_mode));
         }
         break;
     }
   }
 
   for (; property_index < properties()->length(); property_index++) {
     ObjectLiteral::Property* property = properties()->at(property_index);
 
     Expression* value = property->value();
-    if (property->kind() != ObjectLiteral::Property::PROTOTYPE) {
+    if (!property->IsPrototype()) {
       if (FunctionLiteral::NeedsHomeObject(value)) {
         property->SetSlot(spec->AddStoreICSlot(language_mode));
       }
     }
     property->SetStoreDataPropertySlot(
         spec->AddStoreDataPropertyInLiteralICSlot());
   }
 }
 
 
 void ObjectLiteral::CalculateEmitStore(Zone* zone) {
   const auto GETTER = ObjectLiteral::Property::GETTER;
   const auto SETTER = ObjectLiteral::Property::SETTER;
 
   ZoneAllocationPolicy allocator(zone);
 
   CustomMatcherZoneHashMap table(
       Literal::Match, ZoneHashMap::kDefaultHashMapCapacity, allocator);
   for (int i = properties()->length() - 1; i >= 0; i--) {
     ObjectLiteral::Property* property = properties()->at(i);
     if (property->is_computed_name()) continue;
-    if (property->kind() == ObjectLiteral::Property::PROTOTYPE) continue;
+    if (property->IsPrototype()) continue;
     Literal* literal = property->key()->AsLiteral();
     DCHECK(!literal->IsNullLiteral());
 
     // If there is an existing entry do not emit a store unless the previous
     // entry was also an accessor.
     uint32_t hash = literal->Hash();
     ZoneHashMap::Entry* entry = table.LookupOrInsert(literal, hash, allocator);
     if (entry->value != NULL) {
       auto previous_kind =
           static_cast<ObjectLiteral::Property*>(entry->value)->kind();
       if (!((property->kind() == GETTER && previous_kind == SETTER) ||
             (property->kind() == SETTER && previous_kind == GETTER))) {
         property->set_emit_store(false);
       }
     }
     entry->value = property;
   }
 }
 
 
 bool ObjectLiteral::IsBoilerplateProperty(ObjectLiteral::Property* property) {
-  return property != NULL &&
-         property->kind() != ObjectLiteral::Property::PROTOTYPE;
+  return property != NULL && !property->IsPrototype();
 }
 
 void ObjectLiteral::InitDepthAndFlags() {
   if (depth_ > 0) return;
 
   int position = 0;
   // Accumulate the value in local variables and store it at the end.
   bool is_simple = true;
   int depth_acc = 1;
   uint32_t max_element_index = 0;
   uint32_t elements = 0;
   for (int i = 0; i < properties()->length(); i++) {
     ObjectLiteral::Property* property = properties()->at(i);
     if (!IsBoilerplateProperty(property)) {
+      // __proto__:null at the first position has no side-effects and is set

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

Why do you say "first position"? The placement of the null proto isn't
important, I don't think.

+      // directly on the boilerplate.
+      if (property->IsNullPrototype()) continue;
       is_simple = false;
       continue;
     }
 
     if (static_cast<uint32_t>(position) == boilerplate_properties_ * 2) {
       DCHECK(property->is_computed_name());
       is_simple = false;
       break;
     }
     DCHECK(!property->is_computed_name());
@@ skipping 551 matching lines @@
 #ifdef DEBUG
   return is_jsruntime() ? NameForNativeContextIntrinsicIndex(context_index_)
                         : function_->name;
 #else
   return is_jsruntime() ? "(context function)" : function_->name;
 #endif  // DEBUG
 }
 
 }  // namespace internal
 }  // namespace v8