public inbox for libstdc++-cvs@sourceware.org help / color / mirror / Atom feed
From: Jonathan Wakely <redi@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r11-3040] libstdc++: Simplify chrono::duration::_S_gcd Date: Mon, 7 Sep 2020 19:12:22 +0000 (GMT) [thread overview] Message-ID: <20200907191222.5244F386186A@sourceware.org> (raw) https://gcc.gnu.org/g:ec5096f48bbd7db83cbe94bdd3235c5808a5979a commit r11-3040-gec5096f48bbd7db83cbe94bdd3235c5808a5979a Author: Jonathan Wakely <jwakely@redhat.com> Date: Mon Sep 7 20:09:17 2020 +0100 libstdc++: Simplify chrono::duration::_S_gcd We can simplify this constexpr function further because we know that period::num >= 1 and period::den >= 1 so only the remainder can ever be zero. libstdc++-v3/ChangeLog: * include/std/chrono (duration::_S_gcd): Use invariant that neither value is zero initially. Diff: --- libstdc++-v3/include/std/chrono | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/libstdc++-v3/include/std/chrono b/libstdc++-v3/include/std/chrono index 0e2efb2522b..afee7859c6d 100644 --- a/libstdc++-v3/include/std/chrono +++ b/libstdc++-v3/include/std/chrono @@ -430,17 +430,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION // Duration only allows positive periods so we don't need to // handle negative values here (unlike __static_gcd and std::gcd). #if __cplusplus >= 201402L - while (__m != 0 && __n != 0) + do { intmax_t __rem = __m % __n; __m = __n; __n = __rem; } - return __m + __n; + while (__n != 0); + return __m; #else // C++11 doesn't allow loops in constexpr functions, but this // recursive version can be more expensive to evaluate. - return (__m == 0) ? __n : (__n == 0) ? __m : _S_gcd(__n, __m % __n); + return (__n == 0) ? __m : _S_gcd(__n, __m % __n); #endif }
reply other threads:[~2020-09-07 19:12 UTC|newest] Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
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=20200907191222.5244F386186A@sourceware.org \ --to=redi@gcc.gnu.org \ --cc=gcc-cvs@gcc.gnu.org \ --cc=libstdc++-cvs@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).