585090 - Need even faster js-wrapping of natives

Status: RESOLVED FIXED

(Core :: XPConnect, defect)

Description

[Boris Zbarsky [:bzbarsky]]

Looking at dromaeo profiles, xpc_qsXPCOMObjectToJsval features rather prominently in a lot of the DOM ones (> 20% for any of them).  Looking at the actual time breakdown, about 2/3 of the time for this function is spent under XPCConvert::NativeInterface2JSObject.  The other third is basically setting up that call: tons of movs from [epb+something] to [esp+something] (all via registers, too!).

Similar for setting up the call to xpc_qsXPCOMObjectToJsval to start with; a good bit of time in the original quickstub is spent doing that.

Maybe this is all better on x86-64, but on 32-bit it's painful.  I'm not sure what we can do to decrease all this overhead, unfortunately.

Comment 1

[Boris Zbarsky [:bzbarsky]]

Attachment: Proof of concept

Totally not ok to land given the naming, but speeds up the dromaeo first-child test for me by 3% for example....

Comment 2

[Boris Zbarsky [:bzbarsky]]

And I bet if NativeInterface2JSObject took a struct (the same struct as the other method takes, perhaps?) we could do even better.

Comment 3

[Peter Van der Beken [:peterv]]

I think I do some of this in bug 565742.

Comment 4

[Boris Zbarsky [:bzbarsky]]

In that you eliminate some of the args?  Yeah... I just wonder whether we should eliminate all of them.

Comment 5

[Peter Van der Beken [:peterv]]

I think we've done enough on wrapping performance to close this?

Comment 6

[Boris Zbarsky [:bzbarsky]]

Yeah, I think so.  Certainly the current setup is quite different from what comment 0 talks about and the attached patch tries to mess with.