Stream: t-compiler

Topic: planning meeting 2020-03-13


pnkfelix (Mar 13 2020 at 13:51, on Zulip):

Hi @T-compiler/meeting . Planning meeting today, which if I'm not mistaken starts in 9 minutes... ?

simulacrum (Mar 13 2020 at 13:52, on Zulip):

That's what I expected, yes.

pnkfelix (Mar 13 2020 at 13:54, on Zulip):

For reference, here is the proposals list; and here is the protocol for submitting new proposals

pnkfelix (Mar 13 2020 at 13:54, on Zulip):

(because, you know, I'm expecting a flood of new proposals in the next six minutes ... :wink: )

pnkfelix (Mar 13 2020 at 14:01, on Zulip):

Hi @T-compiler/meeting , lets get the planning meeting started. Add a :wave: emoji to this message to show you are here.

eddyb (Mar 13 2020 at 14:02, on Zulip):

pnkfelix said:

(because, you know, I'm expecting a flood of new proposals in the next six minutes ... :wink: )

implement worldwide UBI so that I can spend most days writing proposals

eddyb (Mar 13 2020 at 14:02, on Zulip):

instead of perpetually stressing to finish things started 2-3 years ago

pnkfelix (Mar 13 2020 at 14:03, on Zulip):

I thought you had written "worldwide UB" at first and that set my brain off on quite a tangent

eddyb (Mar 13 2020 at 14:03, on Zulip):

that's more like what's happening right now

pnkfelix (Mar 13 2020 at 14:03, on Zulip):

So lets start off with five minutes for ...

pnkfelix (Mar 13 2020 at 14:04, on Zulip):

Announcements

nikomatsakis (Mar 13 2020 at 14:04, on Zulip):
eddyb (Mar 13 2020 at 14:05, on Zulip):

oh wow I should check the forums more often

pnkfelix (Mar 13 2020 at 14:05, on Zulip):

(or months?)

nikomatsakis (Mar 13 2020 at 14:05, on Zulip):

"at the end of this month"

pnkfelix (Mar 13 2020 at 14:05, on Zulip):

oh oh, "in a few weeks " was the text; I misread it.

pnkfelix (Mar 13 2020 at 14:06, on Zulip):
pnkfelix (Mar 13 2020 at 14:06, on Zulip):

but a very pragmatic issue for both niko and myself is that schools are closed in our area of the USA

nikomatsakis (Mar 13 2020 at 14:07, on Zulip):
nikomatsakis (Mar 13 2020 at 14:07, on Zulip):

oh, yes, jinx

pnkfelix (Mar 13 2020 at 14:08, on Zulip):

right, same here. I'm hoping/planning to continue to work, but its not certain if I can keep a full time schedule.

oli (Mar 13 2020 at 14:08, on Zulip):

I want to call some attention to https://github.com/rust-lang/rust/pull/69916 (--bless for mir_opt tests). Please complain about look and feel or anything else that comes to mind

eddyb (Mar 13 2020 at 14:08, on Zulip):

yes please bikeshed the next-gen mir-opt testing :D

pnkfelix (Mar 13 2020 at 14:08, on Zulip):

Wow!!

eddyb (Mar 13 2020 at 14:09, on Zulip):

I've wanted this for years and the use of diffs is even more clever than things I came up with so kudos on that

pnkfelix (Mar 13 2020 at 14:11, on Zulip):

Okay so it looks like that's all for announcemens?

pnkfelix (Mar 13 2020 at 14:11, on Zulip):

Our list of proposals is pretty light weight this time around

nikomatsakis (Mar 13 2020 at 14:11, on Zulip):
Santiago Pastorino (Mar 13 2020 at 14:12, on Zulip):

@nikomatsakis going to take the one you pointed to me yesterday

nikomatsakis (Mar 13 2020 at 14:12, on Zulip):

I think @Santiago Pastorino was going to make minutes for Focused and Efficient Triage, but parser library-ification and IDE strategy..

nikomatsakis (Mar 13 2020 at 14:12, on Zulip):

I guess at this pont we should just put in a placeholder that points to the zulip archives :)

Santiago Pastorino (Mar 13 2020 at 14:13, on Zulip):

maybe good to assign that one to me, will do :)

nikomatsakis (Mar 13 2020 at 14:13, on Zulip):

anyway, let's get started yeah

pnkfelix (Mar 13 2020 at 14:14, on Zulip):

proposals

pnkfelix (Mar 13 2020 at 14:14, on Zulip):

According to the labels, there are only three that weren't already scheduled (and executed, just lacking minutes)

nikomatsakis (Mar 13 2020 at 14:14, on Zulip):

/poll What to discuss and/or schedule

nikomatsakis (Mar 13 2020 at 14:15, on Zulip):

pnkfelix said:

According to the labels, there are only three that weren't already scheduled (and executed, just lacking minutes)

sorry I should let you steer :) we're racing a bit

pnkfelix (Mar 13 2020 at 14:15, on Zulip):

No no its fine

pnkfelix (Mar 13 2020 at 14:15, on Zulip):

You have the protocol here down more

pnkfelix (Mar 13 2020 at 14:15, on Zulip):

you can steer

nikomatsakis (Mar 13 2020 at 14:16, on Zulip):

let's also clarify the dates involved

pnkfelix (Mar 13 2020 at 14:16, on Zulip):

I was trying to figure out whether the "merge llvm.side-effect change" was still an active proposal

nikomatsakis (Mar 13 2020 at 14:16, on Zulip):
nikomatsakis (Mar 13 2020 at 14:16, on Zulip):

pnkfelix said:

I was trying to figure out whether the "merge llvm.side-effect change" was still an active proposal

well, last time we discussed, we said we'd make a blog post, and @simulacrum has a draft PR

pnkfelix (Mar 13 2020 at 14:17, on Zulip):

right; we discussed it in a planning meeting previously.

nikomatsakis (Mar 13 2020 at 14:17, on Zulip):

I'm inclined to say "no" -- that we should post that blog post and see what feedback we get

Wesley Wiser (Mar 13 2020 at 14:17, on Zulip):

I see @oli reacted with :phone:. Does the poll not work on mobile?

nikomatsakis (Mar 13 2020 at 14:17, on Zulip):

but @simulacrum was asking for feedback

nikomatsakis (Mar 13 2020 at 14:17, on Zulip):

I don't think polls work on mobile, we should bother zulip about it

simulacrum (Mar 13 2020 at 14:17, on Zulip):

We're planning on posting next thursday (though could do sooner I guess) and I think it'll hopefully garner feedback by next cycle

simulacrum (Mar 13 2020 at 14:18, on Zulip):

but this cycle I think I'd skip it

simulacrum (Mar 13 2020 at 14:18, on Zulip):

it may or may not be ready by the last week but not really worth it imo

nikomatsakis (Mar 13 2020 at 14:18, on Zulip):

ok, so, let's look at the remaining two

nikomatsakis (Mar 13 2020 at 14:18, on Zulip):

to start

nikomatsakis (Mar 13 2020 at 14:18, on Zulip):

cranelift backend for rustc

pnkfelix (Mar 13 2020 at 14:18, on Zulip):

Anyway it seems like our democracy worked here

nikomatsakis (Mar 13 2020 at 14:18, on Zulip):

this is https://github.com/rust-lang/compiler-team/issues/257

pnkfelix (Mar 13 2020 at 14:18, on Zulip):

pnkfelix said:

Anyway it seems like our democracy worked here

(in that the "merge llvm.sideeffect" got zero votes)

nikomatsakis (Mar 13 2020 at 14:19, on Zulip):

I think what could be useful is to discuss what to focus the meeting on

nikomatsakis (Mar 13 2020 at 14:19, on Zulip):

cc @bjorn3 if you're around

nikomatsakis (Mar 13 2020 at 14:19, on Zulip):

context:

nikomatsakis (Mar 13 2020 at 14:19, on Zulip):

Over the course of the past ~1.5 year I have been working on a Cranelift based codegen backend for rustc (rustc_codegen_cranelift or cg_clif for short). It is currently complete enough to compile many programs. While there are cases where LLVM is faster, Cranelift is already faster than LLVM in many cases.

bjorn3 (Mar 13 2020 at 14:20, on Zulip):

I am around, but I don't know if I can stay around.

nikomatsakis (Mar 13 2020 at 14:20, on Zulip):

there was also some discussion in #t-compiler > cranelift backend work

simulacrum (Mar 13 2020 at 14:20, on Zulip):

I think @bjorn3 had a list of questions in that hackmd

simulacrum (Mar 13 2020 at 14:20, on Zulip):
nikomatsakis (Mar 13 2020 at 14:20, on Zulip):

that hackmd doesn't seemed to be linked from the issue

nikomatsakis (Mar 13 2020 at 14:20, on Zulip):

can someone post the link here and I'll edit it in?

bjorn3 (Mar 13 2020 at 14:21, on Zulip):

I was waiting for feedback

simulacrum (Mar 13 2020 at 14:21, on Zulip):

https://hackmd.io/@bjorn3/HJL5ryFS8#Key-design-questions

nikomatsakis (Mar 13 2020 at 14:21, on Zulip):

bjorn3 said:

I was waiting for feedback

no reason to wait :) we usually post the draft in there and just shape it

eddyb (Mar 13 2020 at 14:22, on Zulip):

I am likely going to spend the next few months on trait system stuff, otherwise I would love to help with integration and ironing out LLVM vs Cranelift kinks

eddyb (Mar 13 2020 at 14:23, on Zulip):

especially what I was doing a couple months ago, with MIR optimizations and debuginfo, would've fit really well :(

nikomatsakis (Mar 13 2020 at 14:23, on Zulip):

simulacrum said:

I'm happy with these questions :)

nikomatsakis (Mar 13 2020 at 14:23, on Zulip):

maybe we should just schedule it? is there a week that would be preferred?

nikomatsakis (Mar 13 2020 at 14:23, on Zulip):

nikomatsakis said:

nikomatsakis (Mar 13 2020 at 14:24, on Zulip):

I think i'm available all those dates, but I have a slight preference to avoid March 20th

nikomatsakis (Mar 13 2020 at 14:24, on Zulip):

actually I might not be availble April 3

pnkfelix (Mar 13 2020 at 14:24, on Zulip):

Is there somewhere I can read about the lack of alloca support? Or should we add stuff regarding that as questions for the meeting as well?

bjorn3 (Mar 13 2020 at 14:24, on Zulip):

I it is during the evening in Europe I don't have any preference

nikomatsakis (Mar 13 2020 at 14:24, on Zulip):

(I'm supposed to be in a conference in Ireland but I'm sort of expecting that will change b/c COVID-19)

nikomatsakis (Mar 13 2020 at 14:25, on Zulip):

wait that's not true

eddyb (Mar 13 2020 at 14:25, on Zulip):

ABI compatibility is a good direction because I think it should be possible given the ty::layout and FnAbi computations that are outside of LLVM-specific code, and if need be we can improve those to be even more backend-agnostic

nikomatsakis (Mar 13 2020 at 14:25, on Zulip):

bjorn3 said:

I it is during the evening in Europe I don't have any preference

good point, we traditionally do it at 10am Boston time (time in Europe varies I guess because of DST)

nikomatsakis (Mar 13 2020 at 14:25, on Zulip):

but we could change time perhaps

nikomatsakis (Mar 13 2020 at 14:25, on Zulip):

as that would be 15:00 or 16:00 I thnk

bjorn3 (Mar 13 2020 at 14:25, on Zulip):

pnkfelix said:

Is there somewhere I can read about the lack of alloca support? Or should we add stuff regarding that as questions for the meeting as well?

https://github.com/bytecodealliance/wasmtime/issues/1105

pnkfelix (Mar 13 2020 at 14:26, on Zulip):

yeah I don't remember when the EU time change will be

nikomatsakis (Mar 13 2020 at 14:26, on Zulip):

@bjorn3 what's your preferred hour?

eddyb (Mar 13 2020 at 14:26, on Zulip):

@pnkfelix I always remember it as "first weekend after the spring equinox" but I wonder how wrong that is

eddyb (Mar 13 2020 at 14:26, on Zulip):

since it's more heuristic than learned

eddyb (Mar 13 2020 at 14:27, on Zulip):

google says March 29

eddyb (Mar 13 2020 at 14:27, on Zulip):

maybe it's just the last weekend of the month

eddyb (Mar 13 2020 at 14:28, on Zulip):

/me stops trying to guess things that are easily looked up online

nikomatsakis (Mar 13 2020 at 14:28, on Zulip):

regardless it's not evening :)

nikomatsakis (Mar 13 2020 at 14:29, on Zulip):

I'm not sure if @bjorn3 is still around to answer with their preferred hour, but it seems to me like we should have them present at the meeting

eddyb (Mar 13 2020 at 14:29, on Zulip):

it's currently 4:29pm here, for @bjorn3 probably 3:29pm

nikomatsakis (Mar 13 2020 at 14:29, on Zulip):

so i'd be inclined to move a few hours later

pnkfelix (Mar 13 2020 at 14:30, on Zulip):

Regarding date: Given that we only have two real proposals on the table, I'm inclined to not schedule anything for next Friday

bjorn3 (Mar 13 2020 at 14:30, on Zulip):

I would prefer after ~15:00 UTC+02 I believe. @eddyb That's right.

nikomatsakis (Mar 13 2020 at 14:30, on Zulip):

If we do April 3rd at the usual time, that'd be 16:00 :)

eddyb (Mar 13 2020 at 14:30, on Zulip):

that will also work for me starting April, as we'll no longer be renting an office (planned before ever hearing about covid-19, funnily enough), so my schedule will be far more flexible

nikomatsakis (Mar 13 2020 at 14:31, on Zulip):

so let's say Apr 3

pnkfelix (Mar 13 2020 at 14:31, on Zulip):

at the usual time, right?

nikomatsakis (Mar 13 2020 at 14:31, on Zulip):

right

bjorn3 (Mar 13 2020 at 14:32, on Zulip):

nikomatsakis said:

If we do April 3rd at the usual time, that'd be 16:00 :)

Local time for me?

pnkfelix (Mar 13 2020 at 14:32, on Zulip):

(thanks to aforementioned EU time shift)

nikomatsakis (Mar 13 2020 at 14:32, on Zulip):

the other proposed topic was

eddyb (Mar 13 2020 at 14:33, on Zulip):

yeah outside of the March zone of US mismatch, that time is 17:00 for me (and I'm 1hr east of @bjorn3)

pnkfelix (Mar 13 2020 at 14:33, on Zulip):

right. so would we want a meeting about "compile time analysis and assistance" on March 27th?

simulacrum (Mar 13 2020 at 14:33, on Zulip):

I think the open question here is whether this is something we're ready to discuss, and what exactly we'd be discussing

nikomatsakis (Mar 13 2020 at 14:33, on Zulip):

right, that

eddyb (Mar 13 2020 at 14:34, on Zulip):

@nikomatsakis aka what I wanted to put up as a service on profile.lyken.rs :P?

simulacrum (Mar 13 2020 at 14:34, on Zulip):

We would almost certainly want @Wesley Wiser in attendance for self-profile, I guess

nikomatsakis (Mar 13 2020 at 14:34, on Zulip):

I am somewhat inclined to close this issue personally, because I feel like I haven't crystallized the thing that'd be useful to discuss in this setting, but

pnkfelix (Mar 13 2020 at 14:34, on Zulip):

Well, here's a question I have: Do we think the benchmarks on perf.rlo are the right representative for us to be optimizing?

bjorn3 (Mar 13 2020 at 14:34, on Zulip):

eddyb said:

yeah outside of the March zone of US mismatch, that time is 17:00 for me (and I'm 1hr east of bjorn3)

:+1:

pnkfelix (Mar 13 2020 at 14:34, on Zulip):

I.e. maybe a meeting dedicated to discussing what benchmarks would be better?

nikomatsakis (Mar 13 2020 at 14:34, on Zulip):

interesting

pnkfelix (Mar 13 2020 at 14:35, on Zulip):

I was for example musing about just recompiling Servo incrementally across each of its merge commits

nikomatsakis (Mar 13 2020 at 14:35, on Zulip):

that's a different meeting proposal

pnkfelix (Mar 13 2020 at 14:35, on Zulip):

Yes I guess it is. :)

nikomatsakis (Mar 13 2020 at 14:35, on Zulip):

but maybe a good one :)

simulacrum (Mar 13 2020 at 14:35, on Zulip):

yeah sounds like a different meeting, but perhaps a more useful one :)

pnkfelix (Mar 13 2020 at 14:35, on Zulip):

Okay well maybe I'll think about drafting such a proposal for the next go round.

bjorn3 (Mar 13 2020 at 14:35, on Zulip):

I have to go.

nikomatsakis (Mar 13 2020 at 14:35, on Zulip):

I say we leave the "design meeting" unscheduled, close this particular issue,

simulacrum (Mar 13 2020 at 14:35, on Zulip):

I'd be down for not scheduling more than one meeting

pnkfelix (Mar 13 2020 at 14:35, on Zulip):

Right now the USA is so bonkers with COVID-19 panic, that I don't think it would be the end of the world, so to speak, to just leave the rest of March empty

simulacrum (Mar 13 2020 at 14:35, on Zulip):

i.e. just cranelift

nikomatsakis (Mar 13 2020 at 14:35, on Zulip):

and we try to have repare proposals for next time

nikomatsakis (Mar 13 2020 at 14:36, on Zulip):

pnkfelix said:

Right now the USA is so bonkers with COVID-19 panic, that I don't think it would be the end of the world, so to speak, to just leave the rest of March empty

right

simulacrum (Mar 13 2020 at 14:36, on Zulip):

(perhaps worth also noting that I imagine it may be useful to have the option to spill cranelift into a second week or so)

simulacrum (Mar 13 2020 at 14:37, on Zulip):

but I guess if we go with april 3rd that's not really available anyway

nikomatsakis (Mar 13 2020 at 14:37, on Zulip):

OK, so, I move we set the schedule to:

Do I hear a second?

pnkfelix (Mar 13 2020 at 14:37, on Zulip):

@simulacrum that's an interesting point. Maybe we can decide on April 3rd whether to do that, based on how many proposals have been opened by that time?

pnkfelix (Mar 13 2020 at 14:37, on Zulip):

@nikomatsakis seconded.

simulacrum (Mar 13 2020 at 14:37, on Zulip):

:thumbs_up: on that approach from me

nikomatsakis (Mar 13 2020 at 14:37, on Zulip):

(I agree with @pnkfelix that I'd like to keep March flexible right now, things are developing a bit quickly here)

nikomatsakis (Mar 13 2020 at 14:38, on Zulip):

OK, thanks all!

nikomatsakis (Mar 13 2020 at 14:38, on Zulip):

@bjorn3 and @eddyb I'm going to add you two specially to the calendar invite

nikomatsakis (Mar 13 2020 at 14:38, on Zulip):

though @bjorn3 you can privmsg me your e-mail maybe...

pnkfelix (Mar 13 2020 at 14:38, on Zulip):

@simulacrum (or we can keep the existing cadence, and let the spillover cranelift meeting get scheduled during the planning meeting on April 10th... we'll figure it out)

nikomatsakis (Mar 13 2020 at 14:38, on Zulip):

(as always, a reminder to folks, I'm happy to add them to calendar invites as "invitees" if it helps them to remember)

Last update: May 29 2020 at 16:30UTC