> On Mon, Jul 17, 2023 at 12:36 PM Jan Hubicka via Gcc-patches > <gcc-patches@gcc.gnu.org> wrote: > > > > Hi, > > While looking into sphinx3 regression I noticed that vectorizer produces > > BBs with overall probability count 120%. This patch fixes it. > > Richi, I don't know how to create a testcase, but having one would > > be nice. > > > > Bootstrapped/regtested x86_64-linux, commited last night (sorry for > > late email) > > This should trigger with sth like > > for (i) > if (cond[i]) > out[i] = 1.; > > so a masked store and then using AVX2+. ISTR we disable AVX masked > stores on zen (but not AVX512).
OK, let me see if I can get a testcase out of that. > > efalse = make_edge (bb, store_bb, EDGE_FALSE_VALUE); > > /* Put STORE_BB to likely part. */ > > efalse->probability = profile_probability::unlikely (); > > + e->probability = efalse->probability.invert (); > > store_bb->count = efalse->count (); > > isn't the count also wrong? Or rather efalse should be likely(). We're > testing doing > > if (!mask all zeros) > masked-store > > because a masked store with all zero mask can end up invoking COW page fault > handling multiple times (because it doesn't actually write). Hmm, I only fixed the profile, efalse was already set to unlikely, but indeed I think it should be likely. Maybe we can compute some bound on actual probability by knowing if(cond[i]) probability. If the loop always does factor many ones or zeros, the probability would remain the same. If that is p and they are all independent, the outcome would be (1-p)^factor sp we know the conditoinal shoul dbe in ragne (1-p)^factor....(1-p), right? Honza > > Note -Ofast allows store data races and thus does RMW instead of a masked > store. > > > make_single_succ_edge (store_bb, join_bb, EDGE_FALLTHRU); > > if (dom_info_available_p (CDI_DOMINATORS))
