[Bug ipa/80728] IPA-reference suppresses compiler memory barrier

[amonakov at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80728

--- Comment #8 from Alexander Monakov <amonakov at gcc dot gnu.org> ---
Honza: ping :).  ipa-pure-const might be a better place to mark functions with
compiler memory barriers, as it already computes and propagates "nonfreeing"
property (thus computing "nonbarrier" in ipa-pure-const would allow to use it
in implementation of nonbarrier_call_p).

OTOH ipa-pure-const is optional, so with -fno-ipa-pure-const, ipa-reference
would see most functions as compiler memory barriers.  Although it's possible
to rescan bodies of those functions that ipa-pure-const did not scan, that
seems undesirable.