On Sun, Nov 5, 2023 at 9:13 AM Cassio Neri <cassio.n...@gmail.com> wrote: > > I could not find any entry in gcc's bugzilla for that. Perhaps my search > wasn't good enough.
I filed https://gcc.gnu.org/PR112395 with a first attempt at the patch (will double check it soon). Thanks, Andrew > > > On Sun, 5 Nov 2023 at 15:58, Marc Glisse <marc.gli...@inria.fr> wrote: >> >> On Sun, 5 Nov 2023, Cassio Neri wrote: >> >> > When year_month_day_last::day() was implemented, Dr. Matthias Kretz >> > realised >> > that the operation "& 1" wasn't necessary but we did not patch it at that >> > time. This patch removes the unnecessary operation. >> >> Is there an entry in gcc's bugzilla about having the optimizer handle this >> kind of optimization? >> >> unsigned f(unsigned x){ >> if(x>=32)__builtin_unreachable(); >> return 30|(x&1); // --> 30|x >> } >> >> (that optimization would come in addition to your patch, doing the >> optimization by hand is still a good idea) >> >> It looks like the criterion would be a|(b&c) when the possible 1 bits of b >> are included in the certainly 1 bits of a|c. >> >> -- >> Marc Glisse
