Fix corner case when transforming dictionary to fast elements.

R=verwaest@chromium.org
BUG=v8:2249
TEST=regress-2249.js

Review URL: https://chromiumcodereview.appspot.com/10802051

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12167 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/compiler.cc

@@ -819,8 +819,8 @@ bool Compiler::CompileLazy(CompilationInfo* info) {
 
 
 void Compiler::RecompileParallel(Handle<JSFunction> closure) {
-  ASSERT(closure->IsMarkedForParallelRecompilation());
   if (closure->IsInRecompileQueue()) return;
+  ASSERT(closure->IsMarkedForParallelRecompilation());
 
   Isolate* isolate = closure->GetIsolate();
   if (!isolate->optimizing_compiler_thread()->IsQueueAvailable()) {

src/objects.cc

@@ -12447,6 +12447,24 @@ MaybeObject* StringDictionary::TransformPropertiesToFastFor(
     }
   }
 
+  int inobject_props = obj->map()->inobject_properties();
+
+  // Allocate new map.
+  Map* new_map;
+  MaybeObject* maybe_new_map = obj->map()->CopyDropDescriptors();
+  if (!maybe_new_map->To(&new_map)) return maybe_new_map;
+
+  if (instance_descriptor_length == 0) {
+    ASSERT_LE(unused_property_fields, inobject_props);
+    // Transform the object.
+    new_map->set_unused_property_fields(unused_property_fields);
+    obj->set_map(new_map);
+    obj->set_properties(heap->empty_fixed_array());
+    // Check that it really works.
+    ASSERT(obj->HasFastProperties());
+    return obj;
+  }
+
   // Allocate the instance descriptor.
   DescriptorArray* descriptors;
   MaybeObject* maybe_descriptors =
@@ -12458,7 +12476,6 @@ MaybeObject* StringDictionary::TransformPropertiesToFastFor(
 
   FixedArray::WhitenessWitness witness(descriptors);
 
-  int inobject_props = obj->map()->inobject_properties();
   int number_of_allocated_fields =
       number_of_fields + unused_property_fields - inobject_props;
   if (number_of_allocated_fields < 0) {
@@ -12523,13 +12540,9 @@ MaybeObject* StringDictionary::TransformPropertiesToFastFor(
   ASSERT(current_offset == number_of_fields);
 
   descriptors->Sort(witness);
-  // Allocate new map.
-  Map* new_map;
-  MaybeObject* maybe_new_map = obj->map()->CopyDropDescriptors();
-  if (!maybe_new_map->To(&new_map)) return maybe_new_map;
 
-  new_map->InitializeDescriptors(descriptors);
   new_map->set_unused_property_fields(unused_property_fields);
+  new_map->InitializeDescriptors(descriptors);
 
   // Transform the object.
   obj->set_map(new_map);

test/mjsunit/regress-2249.js

+// Copyright 2012 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.
+
+// Flags: --gc-interval=10 --stress-compaction
+
+var o = {};
+o[Math.pow(2,30)-1] = 0;
+o[Math.pow(2,31)-1] = 0;
+o[1] = 0;