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From: "dartdart26 at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/101923] std::function's move ctor is slower than the copy one for empty source objects Date: Mon, 16 Aug 2021 07:18:12 +0000 [thread overview] Message-ID: <bug-101923-4-izw6a5q8zV@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-101923-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101923 --- Comment #3 from Petar Ivanov <dartdart26 at gmail dot com> --- Thank you for pointing the output on x86! Following that, I checked O2 and O3 on ARM64 and I see differences, though I cannot say what their actual impact is: 02: https://godbolt.org/z/P9Garznef O3: https://godbolt.org/z/Yb1q33YP3 In terms of x86, I ran the benchmark in Quick Bench (I assume x86 as that what the disassembly is) and the results are similar to my findings on ARM64 - move being slower: https://quick-bench.com/q/vK9eSYngutKGo4QSPcdra9gUOI0 The benchmark code seems correct to me, but I might be missing something, might be misusing DoNotOptimize() or there might be some side effects. I am sure this is not a big deal. I was just wondering if adding an if statement is doable and, if yes, it seems like a quick and easy win.
next prev parent reply other threads:[~2021-08-16 7:18 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-08-15 13:17 [Bug libstdc++/101923] New: " dartdart26 at gmail dot com 2021-08-15 13:38 ` [Bug libstdc++/101923] " dartdart26 at gmail dot com 2021-08-15 17:54 ` nok.raven at gmail dot com 2021-08-16 7:18 ` dartdart26 at gmail dot com [this message] 2021-08-16 7:30 ` [Bug tree-optimization/101923] " pinskia at gcc dot gnu.org 2021-08-17 6:09 ` dartdart26 at gmail dot com 2021-08-17 10:00 ` redi at gcc dot gnu.org 2021-08-17 10:25 ` redi at gcc dot gnu.org 2021-08-17 13:24 ` cvs-commit at gcc dot gnu.org 2021-08-18 6:02 ` dartdart26 at gmail dot com 2021-10-12 10:59 ` cvs-commit at gcc dot gnu.org 2022-12-29 22:14 ` pinskia at gcc dot gnu.org
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