On Mon, Sep 27, 2021 at 7:29 PM Richard Biener <richard.guent...@gmail.com> wrote: > > On September 27, 2021 6:07:40 PM GMT+02:00, Aldy Hernandez via Gcc-patches > <gcc-patches@gcc.gnu.org> wrote: > > > > > >On 9/27/21 5:27 PM, Aldy Hernandez wrote: > >> > >> > >> On 9/27/21 5:01 PM, Jeff Law wrote: > >>> > >>> > >>> On 9/24/2021 9:46 AM, Aldy Hernandez wrote: > > > >>> And the big question, is the pass running after VRP2 doing anything > >>> particularly useful? Do we want to try and kill it now, or later? > >> > >> Interesting question. Perhaps if we convert DOM threading to a hybrid > >> model, it will render the post-VRP threader completely useless. Huhh... > >> That could kill 2 birds with one stone... we get rid of a threading > >> pass, and we don't need to worry about as much about the super-fast ranger. > > > >These are just a few of the threading passes at -O2: > > > >a.c.192t.thread3 <-- bck threader > >a.c.193t.dom3 <-- fwd threader > >a.c.194t.strlen1 > >a.c.195t.thread4 <-- bck threader > >a.c.196t.vrp2 > >a.c.197t.vrp-thread2 <-- fwd threader > > > >That's almost 4 back to back threaders! > > > >*pause for effect* > > We've always known we have too many of these once Jeff triplicated all the > backwards threading ones. I do hope we manage to reduce the number for GCC > 12. Esp. If the new ones are slower because they no longer use simple > lattices.
By the way, what is the blessed way of knowing which of the N passes we are in? For instance, there are 4 back threading passes (well 5 with ethread). I'd like to know how to know if I'm in the 4th one, which is the one that runs before VRP2 threading. I know there's gimple_opt_pass::set_pass_param, but that seems to only take a bool. Thanks. Aldy
