public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "law at redhat dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/66726] New: missed optimization, factor conversion out of COND_EXPR Date: Wed, 01 Jul 2015 17:23:00 -0000 [thread overview] Message-ID: <bug-66726-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66726 Bug ID: 66726 Summary: missed optimization, factor conversion out of COND_EXPR Product: gcc Version: unknown Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: law at redhat dot com Target Milestone: --- Given something like this: n = (short unsigned int) mode_size[(unsigned int) mode] * 8 <= 64 ? (int) ((short unsigned int) mode_size[(unsigned int) mode] * 8) : 64; Note the (int) cast on the true arm of the COND_EXPR. As a result of that cast, the transformations to turn a COND_EXPR into a MIN/MAX expression in fold-const.c will not trigger. This could be fixed by a patch to match.pd, but the pattern would only really be applicable to GENERIC and thus isn't considered a good design match for match.pd. We could extend fold-const.c to catch this case, but that would really only help GENERIC as well. The best option it seems would be to catch this in phi-opt which would also take us a step closer to handling pr45397. Testcase: /* { dg-do compile } */ /* { dg-options "-O2 -fdump-tree-original" } */ extern unsigned short mode_size[]; int oof (int mode) { return (64 < mode_size[mode] ? 64 : mode_size[mode]); } /* { dg-final { scan-tree-dump-times "MIN_EXPR" 1 "original" } } */
next reply other threads:[~2015-07-01 17:23 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-07-01 17:23 law at redhat dot com [this message] 2015-07-02 6:21 ` [Bug tree-optimization/66726] " kugan at gcc dot gnu.org 2015-07-02 6:25 ` pinskia at gcc dot gnu.org 2015-07-03 12:12 ` kugan at gcc dot gnu.org 2015-07-03 12:21 ` pinskia at gcc dot gnu.org 2015-07-03 12:25 ` kugan at gcc dot gnu.org 2015-07-06 20:40 ` law at redhat dot com 2015-07-06 20:56 ` law at redhat dot com 2015-07-13 9:47 ` schwab@linux-m68k.org 2015-07-13 21:34 ` law at redhat dot com 2015-07-13 23:39 ` kugan at gcc dot gnu.org 2015-07-14 13:20 ` kugan 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-66726-4@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).