Make sure transitioned arrays efficiently call builtin Array functions

src/ia32/macro-assembler-ia32.cc

-// Copyright 2011 the V8 project authors. All rights reserved.
+// 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.
@@ skipping 471 matching lines @@
     pop(scratch1);
     fstp_d(FieldOperand(elements, key, times_4, FixedDoubleArray::kHeaderSize));
   }
   bind(&done);
 }
 
 
 void MacroAssembler::CheckMap(Register obj,
                               Handle<Map> map,
                               Label* fail,
-                              SmiCheckType smi_check_type) {
+                              SmiCheckType smi_check_type,
+                              MapCheckMode mode) {
   if (smi_check_type == DO_SMI_CHECK) {
     JumpIfSmi(obj, fail);
   }
+
+  Label success;
   cmp(FieldOperand(obj, HeapObject::kMapOffset), Immediate(map));
+  if (mode == ALLOW_ELEMENT_TRANSITION_MAPS) {
+    bool ignore;
+    Map* transitioned_double_map =
+        map->LookupElementsTransitionMap(FAST_DOUBLE_ELEMENTS, &ignore);
+    ASSERT(transitioned_double_map == NULL ||
+           map->elements_kind() == FAST_SMI_ONLY_ELEMENTS);
+    Map* transitioned_fast_element_map =
+        map->LookupElementsTransitionMap(FAST_ELEMENTS, &ignore);
+    ASSERT(transitioned_fast_element_map == NULL ||
+           map->elements_kind() != FAST_ELEMENTS);
+    if (transitioned_fast_element_map != NULL) {
+      j(equal, &success);
+      cmp(FieldOperand(obj, HeapObject::kMapOffset),
+          Immediate(Handle<Map>(transitioned_fast_element_map)));
+    }
+
+    if (transitioned_double_map != NULL) {
+      j(equal, &success);
+      cmp(FieldOperand(obj, HeapObject::kMapOffset),
+          Immediate(Handle<Map>(transitioned_double_map)));
+    }
+  }
   j(not_equal, fail);
+  bind(&success);
 }
 
 
 void MacroAssembler::DispatchMap(Register obj,
                                  Handle<Map> map,
                                  Handle<Code> success,
                                  SmiCheckType smi_check_type) {
   Label fail;
   if (smi_check_type == DO_SMI_CHECK) {
     JumpIfSmi(obj, &fail);
@@ skipping 2176 matching lines @@
     cmp(length, Operand(bitmap_scratch, MemoryChunk::kSizeOffset));
     Check(less_equal, "Live Bytes Count overflow chunk size");
   }
 
   bind(&done);
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32