Make KeyedStores from a sloppy arguments array use a handler.

src/ic/ic.cc

Index: src/ic/ic.cc
diff --git a/src/ic/ic.cc b/src/ic/ic.cc
index e47ad9a618e24fd4e186c4285b8407bf797be5da..9e45a8228f8b20a3a00a53cd713fb03423f5ce60 100644
--- a/src/ic/ic.cc
+++ b/src/ic/ic.cc
@@ -2047,14 +2047,12 @@ MaybeHandle<Object> KeyedStoreIC::Store(Handle<Object> object,
       Handle<JSObject> receiver = Handle<JSObject>::cast(object);
       bool key_is_smi_like = !Object::ToSmi(isolate(), key).is_null();
       if (receiver->elements()->map() ==
-          isolate()->heap()->sloppy_arguments_elements_map()) {
-        if (is_sloppy(language_mode())) {
-          stub = sloppy_arguments_stub();
-        } else {
-          TRACE_GENERIC_IC(isolate(), "KeyedStoreIC", "arguments receiver");
-        }
-      } else if (key_is_smi_like &&
-                 !(target().is_identical_to(sloppy_arguments_stub()))) {
+              isolate()->heap()->sloppy_arguments_elements_map() &&
+          !is_sloppy(language_mode())) {
+        TRACE_GENERIC_IC(isolate(), "KeyedStoreIC", "arguments receiver");

[Jakob Kummerow, 2015/05/28 11:55:00]

I find this code confusing. TRACE_GENERIC should be right where we make the
decision that we don't have a stub for the given situation. Since you're now
falling through to StoreElementStub() below, this decision and the tracing call
should move there.
Am I missing something?

[mvstanton, 2015/05/28 13:23:52]

You certainly found a bug! I need an else before the key_is_smi_like test. I'll
keep the decision to go generic if the language mode is inappropriate for the
sloppy arguments elements map here in the spirit of minimum permutation for now.
But I like your idea of moving all these generic exceptions into the
StoreElementStub for later.

+      }
+
+      if (key_is_smi_like) {
         // We should go generic if receiver isn't a dictionary, but our
         // prototype chain does have dictionary elements. This ensures that
         // other non-dictionary receivers in the polymorphic case benefit