[Bug target/81646] i386 SSE2 compilation mode which preserves psABI stack alignment without requiring it

[fw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81646

--- Comment #5 from Florian Weimer <fw at gcc dot gnu.org> ---
(In reply to H.J. Lu from comment #4)
> You can use -mstackrealign.

I don't want to realign the stack unconditionally for performance reasons.  I
want to preserve alignment for callback functions, and give GCC the option to
use SSE2 where beneficial.  If that's not possible, so be it, considering that
it's only i386.