Basic support for tracking smi-only arrays on ia32.

src/factory.cc

Index: src/factory.cc
diff --git a/src/factory.cc b/src/factory.cc
index 9ed3c441dade430bf0e099d42695829d74b49238..a40dbd7111b87431ef017ddc94763da024544a5c 100644
--- a/src/factory.cc
+++ b/src/factory.cc
@@ -404,10 +404,12 @@ Handle<JSGlobalPropertyCell> Factory::NewJSGlobalPropertyCell(
 }
 
 
-Handle<Map> Factory::NewMap(InstanceType type, int instance_size) {
+Handle<Map> Factory::NewMap(InstanceType type,
+                            int instance_size,
+                            ElementsKind elements_kind) {
   CALL_HEAP_FUNCTION(
       isolate(),
-      isolate()->heap()->AllocateMap(type, instance_size),
+      isolate()->heap()->AllocateMap(type, instance_size, elements_kind),
       Map);
 }
 
@@ -710,7 +712,12 @@ Handle<JSFunction> Factory::NewFunctionWithPrototype(Handle<String> name,
   if (force_initial_map ||
       type != JS_OBJECT_TYPE ||
       instance_size != JSObject::kHeaderSize) {
-    Handle<Map> initial_map = NewMap(type, instance_size);
+    ElementsKind default_elements_kind = FLAG_smi_only_arrays
+        ? FAST_SMI_ONLY_ELEMENTS
+        : FAST_ELEMENTS;
+    Handle<Map> initial_map = NewMap(type,
+                                     instance_size,
+                                     default_elements_kind);
     function->set_initial_map(*initial_map);
     initial_map->set_constructor(*function);
   }
@@ -896,11 +903,26 @@ Handle<JSArray> Factory::NewJSArrayWithElements(Handle<FixedArray> elements,
   Handle<JSArray> result =
       Handle<JSArray>::cast(NewJSObject(isolate()->array_function(),
                                         pretenure));
-  result->SetContent(*elements);
+  SetContent(result, elements);
   return result;
 }
 
 
+void Factory::SetContent(Handle<JSArray> array,
+                         Handle<FixedArray> elements) {
+  CALL_HEAP_FUNCTION_VOID(
+      isolate(),
+      array->SetContent(*elements));
+}
+
+
+void Factory::EnsureCanContainNonSmiElements(Handle<JSArray> array) {
+  CALL_HEAP_FUNCTION_VOID(
+      isolate(),
+      array->EnsureCanContainNonSmiElements());
+}
+
+
 Handle<JSProxy> Factory::NewJSProxy(Handle<Object> handler,
                                     Handle<Object> prototype) {
   CALL_HEAP_FUNCTION(