public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "pb at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug optimization/10982] [arm] poor optimisation of "if (var & const)" Date: Sun, 09 May 2004 17:11:00 -0000 [thread overview] Message-ID: <20040509171131.2570.qmail@sourceware.org> (raw) In-Reply-To: <20030526135310.10982.pb@gcc.gnu.org> ------- Additional Comments From pb at gcc dot gnu dot org 2004-05-09 17:11 ------- For that particular testcase, adding a pattern like the one below seems to allow combine to do the right thing. However, changing the "return 1" to "return 2" prevents this from matching. Something a bit more sophisticated might be needed. -- (define_insn_and_split "*zero_extract_compare0_shifted" [(set (match_operand:SI 0 "s_register_operand" "=r") (ne:SI (zero_extract:SI (match_operand:SI 1 "s_register_operand" "r") (match_operand:SI 2 "const_int_operand" "n") (const_int 0)) (const_int 0))) (clobber (reg:CC CC_REGNUM))] "TARGET_ARM" "#" "" [(parallel [(set (reg:CC_NOOV CC_REGNUM) (compare:CC_NOOV (ashift:SI (match_dup 1) (match_dup 2)) (const_int 0))) (set (match_dup 0) (ashift:SI (match_dup 1) (match_dup 2)))]) (set (match_dup 0) (if_then_else (eq:SI (reg:CC_NOOV CC_REGNUM) (const_int 0)) (match_dup 0) (const_int 1)))] "" ) ;; Match the second half of *zero_extract_compare0_shifted (define_insn "*movsi_conditional" [(set (match_operand:SI 0 "s_register_operand" "=r") (if_then_else (eq:SI (reg:CC_NOOV CC_REGNUM) (const_int 0)) (match_dup 0) (match_operand:SI 1 "const_int_operand" "n")))] "TARGET_ARM" "movne\\t%0, %1" [(set_attr "conds" "use")] ) -- What |Removed |Added ---------------------------------------------------------------------------- Version|unknown |3.4.0 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10982
next prev parent reply other threads:[~2004-05-09 17:11 UTC|newest] Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top 2003-05-26 13:58 [Bug optimization/10982] New: " pb@gcc.gnu.org 2003-06-22 3:29 ` [Bug optimization/10982] " pinskia at physics dot uc dot edu 2004-05-09 17:11 ` pb at gcc dot gnu dot org [this message] 2004-05-17 11:27 ` [Bug target/10982] " rearnsha at gcc dot gnu dot org 2004-05-17 11:32 ` cvs-commit at gcc dot gnu dot org 2004-05-17 11:38 ` rearnsha at gcc dot gnu dot org 2004-05-17 11:40 ` rearnsha 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=20040509171131.2570.qmail@sourceware.org \ --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).