public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "aldyh at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/107009] [13 Regression] massive unnecessary code blowup in vectorizer Date: Fri, 23 Sep 2022 17:56:56 +0000 [thread overview] Message-ID: <bug-107009-4-FZRR8WPMGj@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-107009-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107009 --- Comment #5 from Aldy Hernandez <aldyh at gcc dot gnu.org> --- There are two things needed to fix this regression. First, we need an op1_range entry for bitwise-and, so that the 2->4 edge range has the correct nonzero bits for n_12. <bb 2> [local count: 118111600]: _1 = n_12(D) & 7; if (_1 != 0) goto <bb 3>; [0.00%] else goto <bb 4>; [100.00%] With the correct tweak to range-ops, we have: 2->4 (F) n_12(D) : [irange] size_t [1, 18446744073709551608] NONZERO 0xfffffffffffffff8 Which is correct and what DOM would need from ranger to get the nonzero mask correct. However, set_global_ranges_from_unreachable_edges() in DOM is is only exporting ranges for unreachable edges on the SSA names feeding the final conditional above (_1). It also needs to calculate these ranges for other exports from this BB. In this case, we'd need to do the same thing for n_12 as well as _1. In my conversion of DOM+evrp to DOM+ranger, I missed that evrp was doing this dance for all the ranges it knew about coming out of the BB, not just op1 of the conditional. This is legacy evrp: /* Push updated ranges only after finding all of them to avoid ordering issues that can lead to worse ranges. */ for (unsigned i = 0; i < vrs.length (); ++i) ... ... if (is_fallthru && m_update_global_ranges && all_uses_feed_or_dominated_by_stmt (vrs[i].first, stmt) /* The condition must post-dominate the definition point. */ && (SSA_NAME_IS_DEFAULT_DEF (vrs[i].first) || (gimple_bb (SSA_NAME_DEF_STMT (vrs[i].first)) == pred_e->src))) { set_ssa_range_info (vrs[i].first, vrs[i].second); maybe_set_nonzero_bits (pred_e, vrs[i].first); } All we'd need in theory is to loop over the exports to BB2, and export those if the same logic applies. I have two patches in testing that fix the regression.
next prev parent reply other threads:[~2022-09-23 17:56 UTC|newest] Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-09-22 18:49 [Bug tree-optimization/107009] New: " drepper.fsp+rhbz at gmail dot com 2022-09-22 19:00 ` [Bug tree-optimization/107009] [13 Regression] " mpolacek at gcc dot gnu.org 2022-09-22 20:03 ` aldyh at gcc dot gnu.org 2022-09-23 6:43 ` rguenth at gcc dot gnu.org 2022-09-23 13:57 ` aldyh at gcc dot gnu.org 2022-09-23 17:56 ` aldyh at gcc dot gnu.org [this message] 2022-09-23 17:57 ` aldyh at gcc dot gnu.org 2022-09-23 17:57 ` aldyh at gcc dot gnu.org 2022-09-26 14:42 ` cvs-commit at gcc dot gnu.org 2022-09-26 14:43 ` aldyh at gcc dot gnu.org 2022-09-26 17:25 ` cvs-commit at gcc dot gnu.org
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=bug-107009-4-FZRR8WPMGj@http.gcc.gnu.org/bugzilla/ \ --to=gcc-bugzilla@gcc.gnu.org \ --cc=gcc-bugs@gcc.gnu.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).