[Pkg-rust-maintainers] Bug#973414: rustc: produces non-baseline opcodes for compiler_builtins::int::udiv::__udivmoddi4 on i386

[Fabian Grünbichler]

On Tue, 4 Feb 2025 23:10:15 +0100 Samuel Thibault <sthibault at debian.org> wrote:
> Samuel Thibault, le mar. 04 févr. 2025 12:09:57 +0100, a ecrit:
> > Paul Gevers, le mer. 26 avril 2023 22:09:53 +0200, a ecrit:
> > > We discussed this during the Release Team IRC meeting [1]
> > > http://meetbot.debian.net/debian-release/2023/debian-release.2023-04-26-18.59.html
> > > , and we decided that it's too late in the release cycle to fix
> > > this. We'll accept the de-facto baseline bump for bookworm and
> > > document the fact in the Release Notes.
> > > 
> > > Having said that, without having discussed it, I don't think we object
> > > having support for the previous baseline in trixie, if we still release i386
> > > with it.
> > 
> > AIUI in the end rustc is patching i686 to make it pentiumpro-based, so
> > not actually a baseline bump?
> 
> And it was discussed on
> https://lists.debian.org/debian-devel/2024/11/msg00328.html
> and again today on IRC. Consensus seems to be to raise to SSE2, which
> would fix the x87 unsoundness.

I filed a separate bug for this now (well, several actually):

#1095862 (RC bug on rustc, cloned to llvm-18 and llvm-19 as those are
slated for Trixie)
#1095863 (release.debian.org bug for raising the baseline)

This bug here was about an issue with the same patch that accidentally
didn't lower the baseline enough back before the bookworm release, which
was not fixed on the rustc side but rather "solved" with a baseline
raise ;)