public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "olegendo at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/59401] New: [SH] GBR addressing mode optimization produces wrong code Date: Thu, 05 Dec 2013 20:19:00 -0000 [thread overview] Message-ID: <bug-59401-4@http.gcc.gnu.org/bugzilla/> (raw) http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59401 Bug ID: 59401 Summary: [SH] GBR addressing mode optimization produces wrong code Product: gcc Version: 4.9.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: olegendo at gcc dot gnu.org Target: sh*-*-* The GBR addressing mode optimization which was added in 4.8 is buggy. The following example: struct tcb_t { int x, y, z, w; }; int test_00 (int a, tcb_t* b) { tcb_t* tcb = (a & 5) ? (tcb_t*)__builtin_thread_pointer () : b; return tcb->w + tcb->x; } compiled with -O2 results in: mov.l @(12,gbr),r0 mov r0,r2 mov.l @(0,gbr),r0 rts add r2,r0 which is obviously wrong code. This is because sh_find_base_reg_disp in sh.c will step insns outside the current basic block without any further considerations. This is only OK to do if the predecessor basic block has a fall through edge to the current basic block (i.e. there are no labels in between). Otherwise the address reg in question might be set in multiple basic blocks which must be analyzed. In the above test case GBR addressing modes can't be used actually.
next reply other threads:[~2013-12-05 20:19 UTC|newest] Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top 2013-12-05 20:19 olegendo at gcc dot gnu.org [this message] 2013-12-05 20:43 ` [Bug target/59401] " olegendo at gcc dot gnu.org 2014-10-12 23:14 ` olegendo at gcc dot gnu.org 2014-10-12 23:24 ` olegendo at gcc dot gnu.org 2014-10-13 5:17 ` kkojima at gcc dot gnu.org 2014-10-13 21:18 ` olegendo at gcc dot gnu.org 2014-10-13 22:48 ` olegendo at gcc dot gnu.org 2014-10-14 1:42 ` kkojima at gcc dot gnu.org 2014-10-14 1:51 ` olegendo at gcc dot gnu.org 2014-10-14 2:59 ` kkojima at gcc dot gnu.org 2014-10-14 3:33 ` olegendo at gcc dot gnu.org 2014-10-15 13:45 ` olegendo at gcc dot gnu.org 2014-10-16 12:22 ` olegendo 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-59401-4@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).