public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "sje at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/59371] New: Performance regression in GCC 4.8 and later versions. Date: Mon, 02 Dec 2013 17:59:00 -0000 [thread overview] Message-ID: <bug-59371-4@http.gcc.gnu.org/bugzilla/> (raw) http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59371 Bug ID: 59371 Summary: Performance regression in GCC 4.8 and later versions. Product: gcc Version: 4.9.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: sje at gcc dot gnu.org Target: mips*-*-* If I compile this program with -O2 on MIPS: int foo(int *p, unsigned short c) { signed short i; int x = 0; for (i = 0; i < c; i++) { x = x + *p; p++; } return x; } With GCC 4.7.* or earlier I get loop code that looks like: $L3: lw $5,0($4) addiu $3,$3,1 seh $3,$3 addu $2,$2,$5 bne $3,$6,$L3 addiu $4,$4,4 With GCC 4.8 and later I get: $L3: lw $7,0($4) addiu $3,$3,1 seh $3,$3 slt $6,$3,$5 addu $2,$2,$7 bne $6,$0,$L3 addiu $4,$4,4 This loop has one more instruction in it and is slower. A version of this bug appears in EEMBC 1.1. If I change the loop index to be unsigned then I get the better code but I can't change the benchmark I am testing so I am trying to figure out what changed in GCC and how to generate the faster code.
next reply other threads:[~2013-12-02 17:59 UTC|newest] Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top 2013-12-02 17:59 sje at gcc dot gnu.org [this message] 2013-12-03 9:37 ` [Bug target/59371] [4.8/4.9 Regression] " rguenth at gcc dot gnu.org 2013-12-03 16:42 ` sje at gcc dot gnu.org 2013-12-03 23:10 ` pinskia at gcc dot gnu.org 2013-12-04 1:49 ` macro@linux-mips.org 2013-12-04 1:52 ` pinskia at gcc dot gnu.org 2013-12-05 11:12 ` rguenth at gcc dot gnu.org 2013-12-05 23:43 ` macro@linux-mips.org 2013-12-17 10:33 ` jakub at gcc dot gnu.org 2013-12-19 15:37 ` rguenth at gcc dot gnu.org 2014-01-09 20:40 ` macro@linux-mips.org 2014-05-22 9:07 ` [Bug target/59371] [4.8/4.9/4.10 " rguenth at gcc dot gnu.org 2014-12-19 13:34 ` [Bug target/59371] [4.8/4.9/5 " jakub at gcc dot gnu.org 2015-03-13 20:18 ` sje at gcc dot gnu.org 2015-06-23 8:28 ` [Bug target/59371] [4.8/4.9/5/6 " rguenth at gcc dot gnu.org 2015-06-26 20:02 ` [Bug target/59371] [4.9/5/6 " jakub at gcc dot gnu.org 2015-06-26 20:32 ` jakub at gcc dot gnu.org 2021-05-14 9:47 ` [Bug target/59371] [9/10/11/12 Regression] Performance regression in GCC 4.8/9/10/11/12 " jakub at gcc dot gnu.org 2021-05-17 2:57 ` guojiufu at gcc dot gnu.org 2021-05-17 3:11 ` guojiufu at gcc dot gnu.org 2021-06-01 8:06 ` rguenth at gcc dot gnu.org 2022-05-27 9:35 ` [Bug target/59371] [10/11/12/13 " rguenth at gcc dot gnu.org 2022-06-28 10:30 ` jakub at gcc dot gnu.org 2023-07-07 10:30 ` [Bug target/59371] [11/12/13/14 " rguenth 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-59371-4@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).