885521 - Function.apply is slow when given a typed array as the args parameter

Status: RESOLVED DUPLICATE of bug 1398751

(Core :: JavaScript Engine, defect)

Description

[Till Schneidereit [:till]]

Just going off of something kael mentioned in bug 860574, here:

"Unfortunately, .apply seems to perform awful when passed a typed array for the arguments list"

Should at least be investigated, I guess.

Comment 1

[Katelyn Gadd (:kael)]

For reference, the test case from another bug demonstrates the deopt by passing a Uint8Array to String.fromCharCode.apply, so I've put it in the URL field here as well.

The last time I profiled it in SPS, the code path for passing a non-Array to .apply simply does more work and it's more expensive. Maybe that's unavoidable, but it kind of limits the scenarios where you can use typed arrays - and it will only get worse once people are passing arrays of Typed Objects around.