public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/110551] [11/12/13/14 Regression] an extra mov when doing 128bit multiply Date: Tue, 04 Jul 2023 17:47:02 +0000 [thread overview] Message-ID: <bug-110551-4-LXbgG7y609@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-110551-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110551 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Ever confirmed|0 |1 Keywords| |ra Status|UNCONFIRMED |NEW Last reconfirmed| |2023-07-04 Known to fail| |12.1.0, 14.0, 5.1.0, 7.1.0 Summary|[11/12/13/14 regression] |[11/12/13/14 Regression] an |Suboptimal codegen for 128 |extra mov when doing 128bit |bits multiplication on |multiply |x86_64 | Known to work| |4.9.4 --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- It is an older regression though. ``` #include <stdint.h> void mulx64(uint64_t *x, uint64_t *t) { __uint128_t r = (__uint128_t)*x * 0x9E3779B97F4A7C15ull; *t = (uint64_t)r ^ (uint64_t)( r >> 64 ); } ``` It is just an extra mov. Also the mulx should have allowed the register allocator to do better but it was worse ...
next prev parent reply other threads:[~2023-07-04 17:47 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-07-04 17:26 [Bug rtl-optimization/110551] New: [11 / 12 / 13 /14 regression] Suboptimal codegen for 128 bits multiplication on x86_64 moncef.mechri at gmail dot com 2023-07-04 17:32 ` [Bug target/110551] [11/12/13/14 " pinskia at gcc dot gnu.org 2023-07-04 17:47 ` pinskia at gcc dot gnu.org [this message] 2023-07-04 18:12 ` [Bug target/110551] [11/12/13/14 Regression] an extra mov when doing 128bit multiply moncef.mechri at gmail dot com 2023-07-05 7:06 ` rguenth at gcc dot gnu.org 2023-10-18 19:11 ` roger at nextmovesoftware dot com 2023-10-27 9:05 ` cvs-commit at gcc dot gnu.org 2023-10-29 18:01 ` moncef.mechri at gmail dot com 2023-11-01 10:06 ` ubizjak at gmail dot com 2023-11-01 22:35 ` cvs-commit at gcc dot gnu.org 2023-11-06 19:24 ` moncef.mechri at gmail dot com 2023-11-12 15:48 ` [Bug target/110551] [11/12/13 " roger at nextmovesoftware dot com
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-110551-4-LXbgG7y609@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).