Meeting Notes

On Wed, Oct 9, 2024 at 2:04 PM Michael Wong <fraggamuffin_at_[hidden]> wrote:

> Thanks Khalil, please join now.
>
> On Wed, Oct 9, 2024 at 12:17 PM Khalil Estell via SG14 <
> sg14_at_[hidden]> wrote:
>
>> I'll be there. I can go over my paper.
>>
>> On Wed, Oct 9, 2024, 09:16 Patrice Roy via SG14 <sg14_at_[hidden]>
>> wrote:
>>
>>> I won't be there, sadly, as I have a meeting at work at the same time
>>> and my presence there is required.
>>>
>>> Some updates, though:
>>>
>>> The paper on [[invalidate_dereferencing]] that was presented at CppCon
>>> should be in the next mailing (it's pretty much done).
>>>
>>> There might be another one on a trait that has been requested by some
>>> game developers that contacted me last month, and that I discussed a bit
>>> with the ever wonderful Mark Hoemmen at CppCon. The idea is that
>>> std::has_unique_object_representation<T> currently does not work with a
>>> type T that has floating point data members (due in part to the potential
>>> presence of NaN values), but there are use-cases for such a trait when user
>>> code knows that the floating point numbers therein will not be NaN, or
>>> (maybe) that the only NaN values that could occur would be some canonical
>>> NaN with a fixed bit pattern. If I manage to clean it up in time for the
>>> next mailing, I'll add this one too so feel free to react (either on this
>>> list or directly through email) after you've read it. The tentative name
>>> would be std::is_always_exhaustive<T> (taking the name from the work done
>>> by the fine mdspan people if I understand correctly); we'll adjust if need
>>> be.
>>>
>>> Thanks!
>>>
>>>
>>>
>>>
>>> Le mer. 9 oct. 2024 à 11:07, Guy Davidson via SG14 <
>>> sg14_at_[hidden]> a écrit :
>>>
>>>> I am happy to talk about P3375 reproducible floating-point arithmetic
>>>> but I have already had plenty of SG14/19 time. I've just submitted R1 to
>>>> the papers system, but I would much rather defer to other papers.
>>>>
>>>> On Wed, 9 Oct 2024 at 15:52, Bryan St. Amour via SG14 <
>>>> sg14_at_[hidden]> wrote:
>>>>
>>>>> I may be a bit late, but I should be able to join today's call.
>>>>>
>>>>> On Tue, Oct 08, 2024 at 04:07:20PM -0400, Michael Wong via SG14 wrote:
>>>>> > Hi, this SG14 meeting will focus on Embedded.
>>>>> > We can also continue the discussion on P2966. Are there any other
>>>>> papers?
>>>>> >
>>>>> >
>>>>> > P2966R0 – Making C++ Better for Game Developers: Progress Report
>>>>> > https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2023/p2966r1.pdf
>>>>> >
>>>>> > Michael Wong is inviting you to a scheduled Zoom meeting.
>>>>> > Other then Patrice's ongoing Games paper, are there ny other
>>>>> discussions?
>>>>> >
>>>>> > Topic: SG14 monthly
>>>>> > Time: 2nd Wednesdays 02:00 PM Eastern Time (US and Canada)
>>>>> > Every month on the Second Wed,
>>>>> >
>>>>> > Join from PC, Mac, Linux, iOS or Android:
>>>>> >
>>>>> https://iso.zoom.us/j/93151864365?pwd=aDhOcDNWd2NWdTJuT1loeXpKbTcydz09
>>>>> > Password: 789626
>>>>> >
>>>>> > Or iPhone one-tap :
>>>>> > US: +12532158782,,93151864365# or +13017158592,,93151864365#
>>>>> > Or Telephone:
>>>>> > Dial(for higher quality, dial a number based on your current
>>>>> location):
>>>>> > US: +1 253 215 8782 or +1 301 715 8592 or +1 312 626 6799 or
>>>>> +1
>>>>> > 346 248 7799 or +1 408 638 0968 or +1 646 876 9923 or +1 669 900 6833
>>>>> > or 877 853 5247 (Toll Free)
>>>>> > Meeting ID: 931 5186 4365
>>>>> > Password: 789626
>>>>> > International numbers available:
>>>>> https://iso.zoom.us/u/abRrVivZoD
>>>>> >
>>>>> > Or Skype for Business (Lync):
>>>>> > https://iso.zoom.us/skype/93151864365
>>>>> >
>>>>> > Agenda:
>>>>> >
>>>>> > 1. Opening and introduction
>>>>> >
>>>>> > ISO Code of Conduct
>>>>> > <
>>>>> >
>>>>> https://isotc.iso.org/livelink/livelink?func=ll&objId=20882226&objAction=Open&nexturl=%2Flivelink%2Flivelink%3Ffunc%3Dll%26objId%3D20158641%26objAction%3Dbrowse%26viewType%3D1
>>>>> > *>*
>>>>> >
>>>>> > ISO patent policy.
>>>>> >
>>>>> https://isotc.iso.org/livelink/livelink/fetch/2000/2122/3770791/Common_Policy.htm?nodeid=6344764&vernum=-2
>>>>> >
>>>>> > IEC Code of Conduct:
>>>>> >
>>>>> > https://www.iec.ch/basecamp/iec-code-conduct-technical-work
>>>>> >
>>>>> > WG21 Code of Conduct:
>>>>> >
>>>>> >
>>>>> https://isocpp.org/std/standing-documents/sd-4-wg21-practices-and-procedures
>>>>> >
>>>>> > 1.1 Roll call of participants
>>>>>
>>>> Guy, Paul, Andre, Bjarne, Brad, Gianluca, Jonas, Kris, Matthew,
> Rodrigo, Bryan, Gianluca, Jake, Stefano, Khalil, Michael
>


> >
>>>>> > 1.2 Adopt agenda
>>>>> >
>>>>> > 1.3 Approve minutes from the previous meeting, and approve publishing
>>>>> > previously approved minutes to ISOCPP.org
>>>>> >
>>>>> > 1.4 Action items from previous meetings
>>>>> >
>>>>> > 2. Main issues (125 min)
>>>>> >
>>>>> > 2.1 General logistics
>>>>> >
>>>>> > 2024 planning
>>>>> > C++23 and C++26 status
>>>>> > CPPCON SG14/19
>>>>> >
>>>>> > Future and past meeting plans
>>>>> >
>>>>> > * Jan 10, 2024 02:00 PM ET: Games DONE
>>>>> > * Feb 14, 2024 02:00 PM ET: Embedded DONE
>>>>> > * Mar 13, 2024 02:00 PM ET: Cancelled due to Tokyo 3-18-23
>>>>> > * Apr 10, 2024 02:00 PM ET: Finance DONE
>>>>> > * May 8, 2024 02:00 PM ET: Games DONE
>>>>> > * June 12, 2024 02:00 PM ET: Embedded; St.louis 6-24-29 DONE
>>>>> > * July 10, 2024 02:00 PM ET: Finance DONE
>>>>> > * Aug 14, 2024 02:00 PM ET: Games DONE
>>>>> > * Sep 11, 2024 02:00 PM ET: CPPCON Sept 15-20 so cancelled DONE
>>>>> > * Oct 9, 2024 02:00 PM ET: Embedded
>>>>> > * Nov 13, 2024 02:00 PM ET: Cancelled Wroclaw F2F
>>>>> > * Dec 11, 2024 02:00 PM ET: Finance
>>>>> >
>>>>> > 2.2 Paper reviews
>>>>> > Embedded:
>>>>> > * P3132 Accept attributes with user-defined prefixes
>>>>> > * P3134 Attribute [[asserts_rvo]]
>>>>> > Deterministic Exception for Embedded by James Renwick
>>>>> >
>>>>> https://www.pure.ed.ac.uk/ws/portalfiles/portal/78829292/low_cost_deterministic_C_exceptions_for_embedded_systems.pdf
>>>>> >
>>>>
>>>> https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p3313r0.html
Khalil's talk on noexcept and its impact on exception handling is
highlighted, with suggestions for a shorter, more accessible version.

The discussion focused on the suboptimality of current strategies for
managing exception metadata in C++, particularly with GCC and clang. Key
points included the inefficiency of noexcept functions, such as unnecessary
metadata and increased code size. Proposed solutions included grouping
noexcept functions together to reduce memory usage and using link-time
analysis to identify implicit noexcept functions. The conversation also
highlighted the challenges of dynamic linking and the potential for future
tools to optimize exception handling without relying on noexcept
annotations. The meeting emphasized the need for better compiler
optimizations and guidance for developers.
Action Items

   - [ ] Optimize code size by grouping "no except" functions together.
   - [ ] Investigate link time analysis to determine functions that are
   effectively "no except" without having to label them as such.
   - [ ] Provide recommendations for optimizing code generation for "no
   except" functions.



>>>>> > Freestanding Updates
>>>>> >
>>>>> > Games paper review
>>>>> >
>>>>> > Arthur's suggestions:
>>>>> > (1) I put in the Slack channel
>>>>> > <https://cpplang.slack.com/archives/C3TK2M6HH/p1703947057425609> a
>>>>> while
>>>>> > ago Clang PR #76596 <https://github.com/llvm/llvm-project/pull/76596>,
>>>>> from
>>>>> > one Max Winkler, apparently in game dev. I don't think the PR stands
>>>>> much
>>>>> > chance of getting merged into Clang; but it might still be of
>>>>> interest to
>>>>> > SG14 folks. The issue description is very long and somewhat
>>>>> detailed, and
>>>>> > then there's more discussion/debate in the comments
>>>>> > <
>>>>> https://github.com/llvm/llvm-project/pull/76596#issuecomment-1872601156
>>>>> >.
>>>>> > (I'd actually be interested in talking to Max, but he doesn't
>>>>> publish his
>>>>> > email address on GitHub and I guess that might be on purpose.)
>>>>> >
>>>>> > (2) LEWG will be seeing my P3055 "Relax wording to permit relocation
>>>>> > optimizations in the STL"
>>>>> > <https://quuxplusone.github.io/draft/d3055-relocation.html> in a
>>>>> telecon on
>>>>> > February 20th. (Related blog post.
>>>>> > <https://quuxplusone.github.io/blog/2024/01/02/bsl-vector-erase/>)
>>>>> Might
>>>>> > be interesting to folks who do EASTL-style containers. I'd be
>>>>> interested in
>>>>> > early feedback and/or telecon attendance.
>>>>> >
>>>>> >
>>>>> > Discussion on Embedded:
>>>>> > Paul's suggestions
>>>>> > The next meeting would then be Embedded and I would be interested in
>>>>> > knowing if people think a module std.freestanding is worth pursuing.
>>>>> > In that context I'd like to get some feedback perhaps already for the
>>>>> > upcoming meeting, if people have started using modules, and if so if
>>>>> it has
>>>>> > brought the promised expectations or if you are holding back if you
>>>>> see any
>>>>> > relevance in modules.
>>>>> >
>>>>> > Review latest mailings:
>>>>> > P2532 Removing exception_ptr from the receivers concept
>>>>> > Based on the last meeting and the discussions here.
>>>>> > P2544 C++ Exceptions are becoming more and more problematic
>>>>> > We might want to chime in here.
>>>>> > /Paul
>>>>> > P. S. P2327 de-deprecating volatile received a "consensus" straw
>>>>> poll.
>>>>> >
>>>>> >
>>>>> > Discussion on Low Latency/Finance topics
>>>>> >
>>>>> > http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p1839r4.pdf
>>>>> >
>>>>> >
>>>>> >
>>>>> >
>>>>> >
>>>>> > Discussion about Games topics:
>>>>> >
>>>>> > P2388R1 - Minimum Contract Support: either Ignore or Check_and_abort
>>>>> > <
>>>>> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2388r1.html>
>>>>> >
>>>>> >
>>>>> >
>>>>> >
>>>>> >
>>>>> > 2.2.1 any other proposal for reviews?
>>>>> >
>>>>> >
>>>>> >
>>>>> > SG14/SG19 features/issues/defects:
>>>>> >
>>>>> >
>>>>> https://docs.google.com/spreadsheets/d/1JnUJBO72QVURttkKr7gn0_WjP--P0vAne8JBfzbRiy0/edit#gid=0
>>>>> >
>>>>> > 2.3 Domain-specific discussions
>>>>> >
>>>>> > 2.3.1 SIG chairs
>>>>> >
>>>>> > - Embedded Programming chairs: Ben Craig, Wouter van Ooijen and
>>>>> Odin
>>>>> > Holmes, John McFarlane
>>>>> >
>>>>> > - Financial/Trading chairs: Robin Rowe, Staffan TjernstrÃm
>>>>> > Carl Cooke, Neal Horlock,
>>>>> > - Games chairs: Rene Riviera, Guy Davidson and Paul Hampson,
>>>>> Patrice Roy
>>>>> >
>>>>> > - Linear Algebra chairs: Bob Steagall, Mark Hoemmen, Guy Davidson
>>>>> >
>>>>> > 2.4 Other Papers and proposals
>>>>> >
>>>>> > 2.5 Future F2F meetings:
>>>>> >
>>>>> > 2.6 future C++ Standard meetings:
>>>>> > https://isocpp.org/std/meetings-and-participation/upcoming-meetings
>>>>> >
>>>>> > -
>>>>> >
>>>>> > 3. Any other business
>>>>> > Reflector
>>>>> > https://lists.isocpp.org/mailman/listinfo.cgi/sg14
>>>>> > As well as look through papers marked "SG14" in recent standards
>>>>> committee
>>>>> > paper mailings:
>>>>> > http://open-std.org/jtc1/sc22/wg21/docs/papers/2015/
>>>>> > http://open-std.org/jtc1/sc22/wg21/docs/papers/2016/
>>>>> >
>>>>> > Code and proposal Staging area
>>>>> > https://github.com/WG21-SG14/SG14
>>>>> > 4. Review
>>>>> >
>>>>> > 4.1 Review and approve resolutions and issues [e.g., changes to SG's
>>>>> > working draft]
>>>>> >
>>>>> > 4.2 Review action items (5 min)
>>>>> >
>>>>> > 5. Closing process
>>>>> >
>>>>> > 5.1 Establish next agenda
>>>>> >
>>>>> > 5.2 Future meeting
>>>>> >
>>>>> >
>>>>> > * Jan 10, 2024 02:00 PM ET: Games DONE
>>>>> > * Feb 14, 2024 02:00 PM ET: Embedded DONE
>>>>> > * Mar 13, 2024 02:00 PM ET: Cancelled due to Tokyo 3-18-23
>>>>> > * Apr 10, 2024 02:00 PM ET: Finance DONE
>>>>> > * May 8, 2024 02:00 PM ET: Games DONE
>>>>> > * June 12, 2024 02:00 PM ET: Embedded; St.louis 6-24-29 DONE
>>>>> > * July 10, 2024 02:00 PM ET: Finance
>>>>> > * Aug 14, 2024 02:00 PM ET: Games
>>>>> > * Sep 11, 2024 02:00 PM ET: CPPCON Sept 15-20 so cancelled
>>>>> > * Oct 9, 2024 02:00 PM ET: Embedded
>>>>> > * Nov 13, 2024 02:00 PM ET: Cancelled Wroclaw F2F
>>>>> > * Dec 11, 2024 02:00 PM ET: Finance
>>>>>
>>>>> > _______________________________________________
>>>>> > SG14 mailing list
>>>>> > SG14_at_[hidden]
>>>>> > https://lists.isocpp.org/mailman/listinfo.cgi/sg14
>>>>>
>>>>> _______________________________________________
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>>>>>
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