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From: "soonts at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/96733] New: std::clamp for floats and doubles produces worse code than a combo of std::min / std::max Date: Fri, 21 Aug 2020 10:04:58 +0000 [thread overview] Message-ID: <bug-96733-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96733 Bug ID: 96733 Summary: std::clamp for floats and doubles produces worse code than a combo of std::min / std::max Product: gcc Version: 10.2.0 Status: UNCONFIRMED Keywords: missed-optimization Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: soonts at gmail dot com Target Milestone: --- C++/17 introduced std::clamp in the standard library. Very useful, but the code gcc generates for it is not optimal for doubles and floats. Source code: // This version is good in gcc, not so on vc++ double clamp_minmax( double x, double i, double ax ) { return std::min( std::max( x, i ), ax ); } // This version should be identical but is not. // gcc compiles to scalar comparisons // vc++ code is outright horrible, compiles into RAM access. double clamp_builtin( double x, double i, double ax ) { return std::clamp( x, i, ax ); } Demo there: https://godbolt.org/z/Gnvc1s
next reply other threads:[~2020-08-21 10:04 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-08-21 10:04 soonts at gmail dot com [this message] 2020-08-21 10:42 ` [Bug middle-end/96733] " redi at gcc dot gnu.org 2020-08-23 2:52 ` pinskia at gcc dot gnu.org 2020-08-24 15:36 ` jakub at gcc dot gnu.org 2020-08-24 17:44 ` redi at gcc dot gnu.org 2020-08-24 17:49 ` jakub at gcc dot gnu.org 2020-08-24 19:17 ` [Bug libstdc++/96733] " redi at gcc dot gnu.org 2021-04-12 8:06 ` rguenth at gcc dot gnu.org 2021-05-12 9:55 ` redi at gcc dot gnu.org 2021-10-01 19:38 ` cvs-commit at gcc dot gnu.org 2021-10-01 19:46 ` redi at gcc dot gnu.org 2023-08-12 22:56 ` cosiekvfj at o2 dot pl
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