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

[Fierelier OwO]

* In terms of efficiency: I believe that if people are on the hunt for
efficiency on CPUs at the top-end of x86, they shall use distros that
target Pentium 4 explicitly. There are a few of them out there, now.
Archlinux32 for example carries packages for i486, i686 and Pentium 4
where possible, and lets you enable the architectures that suit you
best.

* In terms of confusion: I think using the Rust i586 toolchain, and
building for i586 with Rust might be less confusing, because altering
the i686 definitions for rustc will make it act differently compared
to other platforms. People could compile code for i686 on Debian, get
working code, but then if someone else does the same on another
distro, the produced binary would not work on the same devices.

Although, I think changing the i686 definition down, like you did, is
the most accurate way to achieve the goal, and is what I personally
think should be mainline. If the accurate definition proves itself on
Debian, it might find itself in mainline Rust, too, which would be
awesome.

Thank you for your continued interest in this topic.