Implement tracking and optimizations of packed arrays.

src/ia32/builtins-ia32.cc

Index: src/ia32/builtins-ia32.cc
diff --git a/src/ia32/builtins-ia32.cc b/src/ia32/builtins-ia32.cc
index a5d42cfbe4c52567849411c44155f2ec0bbc62f9..96f89cd18ab939c9df526a56b0f3399710e3d67b 100644
--- a/src/ia32/builtins-ia32.cc
+++ b/src/ia32/builtins-ia32.cc
@@ -899,7 +899,7 @@ static void AllocateEmptyJSArray(MacroAssembler* masm,
   const int initial_capacity = JSArray::kPreallocatedArrayElements;
   STATIC_ASSERT(initial_capacity >= 0);
 
-  __ LoadInitialArrayMap(array_function, scratch2, scratch1);
+  __ LoadInitialArrayMap(array_function, scratch2, scratch1, false);
 
   // Allocate the JSArray object together with space for a fixed array with the
   // requested elements.
@@ -1002,7 +1002,8 @@ static void AllocateJSArray(MacroAssembler* masm,
   ASSERT(!fill_with_hole || array_size.is(ecx));  // rep stos count
   ASSERT(!fill_with_hole || !result.is(eax));  // result is never eax
 
-  __ LoadInitialArrayMap(array_function, scratch, elements_array);
+  __ LoadInitialArrayMap(array_function, scratch,
+                         elements_array, fill_with_hole);
 
   // Allocate the JSArray object together with space for a FixedArray with the
   // requested elements.
@@ -1273,11 +1274,12 @@ static void ArrayNativeCode(MacroAssembler* masm,
   __ jmp(&prepare_generic_code_call);
 
   __ bind(&not_double);
-  // Transition FAST_SMI_ONLY_ELEMENTS to FAST_ELEMENTS.
+  // Transition Smi-only to Object elements.
   __ mov(ebx, Operand(esp, 0));
   __ mov(edi, FieldOperand(ebx, HeapObject::kMapOffset));
+
   __ LoadTransitionedArrayMapConditional(
-      FAST_SMI_ONLY_ELEMENTS,
+      FAST_SMI_ELEMENTS,
       FAST_ELEMENTS,
       edi,
       eax,