Fix issue 386, a bug in JSObject::ReplaceSlowProperty with constant transitions.

Review URL: http://codereview.chromium.org/141031

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2228 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/objects.cc

@@ -1302,16 +1302,19 @@ Object* JSObject::ReplaceSlowProperty(String* name,
                                        Object* value,
                                        PropertyAttributes attributes) {
   Dictionary* dictionary = property_dictionary();
-  PropertyDetails old_details =
-      dictionary->DetailsAt(dictionary->FindStringEntry(name));
-  int new_index = old_details.index();
-  if (old_details.IsTransition()) new_index = 0;
+  int old_index = dictionary->FindStringEntry(name);
+  int new_enumeration_index = 0;  // 0 means "Use the next available index."
+  if (old_index != -1) {
+    // All calls to ReplaceSlowProperty have had all transitions removed.
+    ASSERT(!dictionary->DetailsAt(old_index).IsTransition());
+    new_enumeration_index = dictionary->DetailsAt(old_index).index();
+  }
 
-  PropertyDetails new_details(attributes, NORMAL, old_details.index());
+  PropertyDetails new_details(attributes, NORMAL, new_enumeration_index);
   Object* result =
-      property_dictionary()->SetOrAddStringEntry(name, value, new_details);
+      dictionary->SetOrAddStringEntry(name, value, new_details);
   if (result->IsFailure()) return result;
-  if (property_dictionary() != result) {
+  if (dictionary != result) {
     set_properties(Dictionary::cast(result));
   }
   return value;

src/objects.h

@@ -2033,6 +2033,7 @@ class Dictionary: public DictionaryBase {
 
   // Returns the property details for the property at entry.
   PropertyDetails DetailsAt(int entry) {
+    ASSERT(entry >= 0);  // Not found is -1, which is not caught by get().
     return PropertyDetails(Smi::cast(get(EntryToIndex(entry) + 2)));
   }
 

test/mjsunit/regress/regress-386.js

+// Copyright 2009 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+// Test for http://code.google.com/p/v8/issues/detail?id=386
+// This test creates enough properties in A so that adding i as
+// a constant function, in the first call to the constructor, leaves
+// the object's map in the fast case and adds a constant function map
+// transition.
+// Adding i in the second call to the constructor creates a real property,
+// and simultaneously converts the object from fast case to slow case
+// and changes i from a map transition to a real property.  There was
+// a flaw in the code that handled this combination of events.
+
+function A() {
+ for (var i = 0; i < 13; i++) {
+   this['a' + i] = i;
+ }
+ this.i = function(){};
+};
+
+new A();
+new A();