public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "amacleod at redhat dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/104526] [12 Regression] Dead Code Elimination Regression at -O3 (trunk vs. 11.2.0) Date: Mon, 14 Feb 2022 22:14:15 +0000 [thread overview] Message-ID: <bug-104526-4-tPSF0Wqtfn@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-104526-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104526 --- Comment #3 from Andrew Macleod <amacleod at redhat dot com> --- (In reply to Jakub Jelinek from comment #2) > and evrp properly figured out those ranges, that 1 / int is [-1, 1] and > that 2 >> [-1, 1] is [1, 2]. > But since r12-6924 the IL is: > c.0_1 = c; > _2 = *c.0_1; > _11 = (unsigned int) _2; > _12 = _11 + 1; > _13 = _12 <= 2; > _3 = _12 <= 2 ? _2 : 0; > So, Andrew/Aldy, how hard would it be to improve ranger COND_EXPR handling, > so that it essentially does what we do for the PHI cases? I.e. from the > COND_EXPR condition, compute "assertion" if condition is true or if > condition is false, and use that on the COND_EXPR's second and third > argument. > So for the > _3 = _12 <= 2 ? _2 : 0; > comparison, for second argument the condition must be true which implies that > _2 must be there [-1, 1], while for the third argument the condition must be > false, but the argument is constant 0, so range is [0, 0], then just union > those 2 ranges. > > As this is a P1 regression, if we can fix it, would be nice to get it into > GCC 12. I'm having a look. The bits are all there. Most of gori is stmt oriented, but I may be able to invoke the components such that we evaluate the 2nd and 3rd arguemnts as if they were on true/false edges to improve the results..
next prev parent reply other threads:[~2022-02-14 22:14 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-02-14 10:07 [Bug tree-optimization/104526] New: " theodort at inf dot ethz.ch 2022-02-14 10:12 ` [Bug tree-optimization/104526] " rguenth at gcc dot gnu.org 2022-02-14 13:41 ` jakub at gcc dot gnu.org 2022-02-14 14:33 ` jakub at gcc dot gnu.org 2022-02-14 22:14 ` amacleod at redhat dot com [this message] 2022-02-15 22:12 ` cvs-commit at gcc dot gnu.org 2022-02-15 22:13 ` amacleod at redhat dot com 2022-02-16 12:39 ` jakub at gcc dot gnu.org 2022-02-16 14:05 ` amacleod at redhat dot com 2022-02-16 14:07 ` jakub 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-104526-4-tPSF0Wqtfn@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).