Only walk the hidden prototype chain for private nonexistent symbols

src/ic/handler-compiler.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/v8.h"
 
 #include "src/cpu-profiler.h"
 #include "src/ic/call-optimization.h"
 #include "src/ic/handler-compiler.h"
 #include "src/ic/ic.h"
@@ skipping 35 matching lines @@
   // therefore the stub will be specific to the name.
   Handle<Name> cache_name =
       receiver_map->is_dictionary_map()
           ? name
           : Handle<Name>::cast(isolate->factory()->nonexistent_symbol());
   Handle<Map> current_map = stub_holder_map;
   Handle<JSObject> last(JSObject::cast(receiver_map->prototype()));
   while (true) {
     if (current_map->is_dictionary_map()) cache_name = name;
     if (current_map->prototype()->IsNull()) break;
+    if (name->IsPrivate()) {
+      // TODO(verwaest): Use nonexistent_private_symbol.
+      cache_name = name;
+      JSReceiver* prototype = JSReceiver::cast(current_map->prototype());
+      if (!prototype->map()->is_hidden_prototype() &&
+          !prototype->map()->IsGlobalObjectMap()) {
+        break;
+      }
+    }
+
     last = handle(JSObject::cast(current_map->prototype()));
     current_map = handle(last->map());
   }
   // Compile the stub that is either shared for all names or
   // name specific if there are global objects involved.
   Handle<Code> handler = PropertyHandlerCompiler::Find(
       cache_name, stub_holder_map, Code::LOAD_IC, flag, Code::FAST);
   if (!handler.is_null()) return handler;
 
   NamedLoadHandlerCompiler compiler(isolate, receiver_map, last, flag);
@@ skipping 355 matching lines @@
 // TODO(verwaest): Cleanup. holder() is actually the receiver.
 Handle<Code> NamedStoreHandlerCompiler::CompileStoreTransition(
     Handle<Map> transition, Handle<Name> name) {
   Label miss;
 
   // Check that we are allowed to write this.
   bool is_nonexistent = holder()->map() == transition->GetBackPointer();
   if (is_nonexistent) {
     // Find the top object.
     Handle<JSObject> last;
+    PrototypeIterator::WhereToEnd end =
+        name->IsPrivate() ? PrototypeIterator::END_AT_NON_HIDDEN
+                          : PrototypeIterator::END_AT_NULL;
     PrototypeIterator iter(isolate(), holder());
-    while (!iter.IsAtEnd()) {
+    while (!iter.IsAtEnd(end)) {
       last = Handle<JSObject>::cast(PrototypeIterator::GetCurrent(iter));
       iter.Advance();
     }
     if (!last.is_null()) set_holder(last);
     NonexistentFrontendHeader(name, &miss, scratch1(), scratch2());
   } else {
     FrontendHeader(receiver(), name, &miss, DONT_RETURN_ANYTHING);
     DCHECK(holder()->HasFastProperties());
   }
 
@@ skipping 113 matching lines @@
         DCHECK(elements_kind == DICTIONARY_ELEMENTS);
         cached_stub = LoadDictionaryElementStub(isolate()).GetCode();
       }
     }
 
     handlers->Add(cached_stub);
   }
 }
 }  // namespace internal
 }  // namespace v8