public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "rguenth at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/42635] New: no-op conversions hinder if-conversion Date: Wed, 06 Jan 2010 15:16:00 -0000 [thread overview] Message-ID: <bug-42635-10053@http.gcc.gnu.org/bugzilla/> (raw) The following two functions are not if-converted at the tree level (the 2nd example happens a lot from VEC code via VEC_BASE): int *bar (char *p) { int *q; if (p) q = (int *)p; else q = (int *)0; return q; } struct X { int q; }; int *foo (struct X *p) { int *q; if (p) q = &p->q; else q = (int *)0; return q; } before phiopt1 we have bar (char * p) { int * q; <bb 2>: if (p_2(D) != 0B) goto <bb 3>; else goto <bb 4>; <bb 3>: q_3 = (int *) p_2(D); <bb 4>: # q_1 = PHI <q_3(3), 0B(2)> return q_1; which can be optimized to just <bb 2>: return (int *) p_2(D); well - with a separate stmt for the conversion. -- Summary: no-op conversions hinder if-conversion Product: gcc Version: 4.5.0 Status: UNCONFIRMED Keywords: missed-optimization Severity: enhancement Priority: P3 Component: tree-optimization AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: rguenth at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42635
next reply other threads:[~2010-01-06 15:16 UTC|newest] Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top 2010-01-06 15:16 rguenth at gcc dot gnu dot org [this message] 2010-01-06 15:17 ` [Bug tree-optimization/42635] " rguenth at gcc dot gnu dot 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-42635-10053@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).