bug#42147: 28.0.50; pure vs side-effect-free, missing optimizations?

[Eli Zaretskii]

> Cc: mattiase@acm.org, monnier@iro.umontreal.ca, andrea_corallo@yahoo.it,
>  42147@debbugs.gnu.org
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Sat, 4 Jul 2020 09:27:23 -0700
> 
> On 7/4/20 9:15 AM, Eli Zaretskii wrote:
> >> * configure.ac: On x86 with GCC, default to -msse2 -mfpmath=sse.
> > This assumes that the system on which Emacs runs is the same as where
> > it was built, doesn't it?
> It doesn't assume they're the same system. It merely assumes that build and
> host platforms both support SSE2, which is a safe assumption nowadays.

What about the effect on the ABI?  If Emacs compiled with these
switches is linked against libraries compiled without them, could
there be problems in the produced binary?