public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "stefano.d at posteo dot de" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/109471] New: Missing loop unrolling for small std::vector? Date: Tue, 11 Apr 2023 10:42:51 +0000 [thread overview] Message-ID: <bug-109471-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109471 Bug ID: 109471 Summary: Missing loop unrolling for small std::vector? Product: gcc Version: 12.2.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: stefano.d at posteo dot de Target Milestone: --- Hi, I did some benchmarks where I wanted to bench a switch-case statement against a small std::vector. In GCC 12.2 the result was as expected: The switch-case statement was faster than the linear search in std::vector. But when I switched to clang 13 or above, the std::vector implementation was much faster than the switch-case statement! You can the results here: https://quick-bench.com/q/9DEDS7rQm0MnIFxwZt3A2iD86G0 Please switch here between GCC and clang. Here an assembly output: https://godbolt.org/z/j8oenP8x9 Kind regards Stefano
next reply other threads:[~2023-04-11 10:42 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-04-11 10:42 stefano.d at posteo dot de [this message] 2023-04-11 13:42 ` [Bug tree-optimization/109471] " rguenth at gcc dot gnu.org 2023-04-11 13:47 ` xry111 at gcc dot gnu.org 2023-04-11 13:49 ` [Bug tree-optimization/109471] Missing loop unrolling for small std::array? stefano.d at posteo dot de 2023-04-11 13:52 ` stefano.d at posteo dot de
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-109471-4@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).