[evilpie]

Thank you mraleph for suggesting these benchmark changes! We already looked at this a while back, but it doesn't look like we kept looking at it. https://bugzilla.mozilla.org/show_bug.cgi?id=650939

A quick look with the JIT inspector addon (https://addons.mozilla.org/en-US/firefox/addon/jit-inspector...) seems to tell me that a lot of performance is gated on the array[i] index access, which you already mentioned. Indeed the polymorphic lookups are hurting us very badly and I think we don't inline cache anything and always take stub call. (Screenshot: http://i.imgur.com/UKL0t.png) All the red sections are the very hot stubcalls.

We only IC properties of regular objects (but also with different shapes and offsets) and indexes into some optimized array kind. But _not_ typed arrays. We used to do this, but Type Inference is usually very good with "normal" usages of typed arrays.