bug#72145: rare Emacs screwups on x86 due to GCC bug 58416

[Po Lu]

Paul Eggert <eggert@cs.ucla.edu> writes:

> On 2024-07-16 22:01, Paul Eggert wrote:
>> We could add an AC_RUN_IFELSE test for SSE2, though I doubt whether
>> it would affect builds significantly in practice.
>
> On second thought the rare Arch or Gentoo user could still be building
> Emacs for the Pentium III, and for such a user a run-time test on the
> build host would be a win. This can be done via the attached revised
> patch. It uses AC_LINK_IFELSE to compile and run a single program,
> instead of AC_RUN_IFELSE which (when combined with AC_COMPILE_IFELSE)
> would mean compiling two test programs and running one.

I'm thinking of the computer where I produce binaries for Windows 9X,
which, being a Windows 98 system, probably does not support SSE2.