Stream: wg-ffi-unwind

Topic: measuring code size


nikomatsakis (Nov 08 2019 at 14:37, on Zulip):

I'm breaking this out into a distinct topic

nikomatsakis (Nov 08 2019 at 14:37, on Zulip):

Thanks @tmandry for those numbers! Very helpful to have an upper bound, and I agree the impact is non-trivial

nikomatsakis (Nov 08 2019 at 14:37, on Zulip):

Given that the impact is non-trivial, it seems like it is worth trying to dig in more, since the impact of these alternatives would be more limited, and it seems like it matters

nikomatsakis (Nov 08 2019 at 16:15, on Zulip):

I think at this point

nikomatsakis (Nov 08 2019 at 16:15, on Zulip):

these measurements are the single most important thing to do

nikomatsakis (Nov 08 2019 at 16:16, on Zulip):

I think @gnzlbg what we really want to compare is

nikomatsakis (Nov 08 2019 at 16:16, on Zulip):

what is the cost if we insert "abort" shims around "C" FFI calls, but otherwise use -Cpanic=abort

nikomatsakis (Nov 08 2019 at 16:16, on Zulip):

I don't think we can estimate that yet, do we need to do a prototype impl to do so?

nikomatsakis (Nov 08 2019 at 16:16, on Zulip):

(Maybe @Amanieu is interested in doing so?)

Kyle Strand (Nov 09 2019 at 00:10, on Zulip):

@nikomatsakis do you have a sense of what threshold should be considered "significant", and how it would impact our design decisions? The data is interesting, but I'm having a little trouble tracking how it will inform our next steps.

Josh Triplett (Nov 09 2019 at 03:45, on Zulip):

The size might determine whether it's reasonable to have C default to unwind or nounwind.

Josh Triplett (Nov 09 2019 at 03:45, on Zulip):

Or at least the impact of those choices.

nikomatsakis (Nov 11 2019 at 21:01, on Zulip):

nikomatsakis do you have a sense of what threshold should be considered "significant", and how it would impact our design decisions? The data is interesting, but I'm having a little trouble tracking how it will inform our next steps.

I feel like 10% is significant

nikomatsakis (Nov 11 2019 at 21:01, on Zulip):

I'm not saying <10% is not significant :)

nikomatsakis (Nov 11 2019 at 21:02, on Zulip):

I guess I think the threshold is probably somewhere around 2 or 3%? I don't really know.

nikomatsakis (Nov 11 2019 at 21:02, on Zulip):

I'd prefer to have the number because there are certain things where it's clear -- 0.1%, or 10% :)

nikomatsakis (Nov 11 2019 at 21:02, on Zulip):

in other words, I don't think there is a firm threshold

Kyle Strand (Nov 11 2019 at 21:59, on Zulip):

Okay, that's fair enough.

Last update: Nov 15 2019 at 10:15UTC