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From: "dangelog at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/102221] Missed optimizations for algorithms over std::unique_ptr Date: Wed, 08 Sep 2021 15:08:21 +0000 [thread overview] Message-ID: <bug-102221-4-E96V8AsL5y@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-102221-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102221 --- Comment #2 from Giuseppe D'Angelo <dangelog at gmail dot com> --- Hi, Thanks for the analysis! That basically allows me to reduce the testcase to something as simple as a swap: #include <memory> #include <utility> #if defined(SMART) using ptr = std::unique_ptr<int>; #else using ptr = int *; #endif auto swap1(ptr &a, ptr &b) { if (&a == &b) __builtin_unreachable(); // ptr tmp(std::move(a)); a = std::move(b); b = std::move(tmp); } auto swap2(ptr &a, ptr &b) { // deliberate std::swap<ptr>(a, b); } https://gcc.godbolt.org/z/Tqzz5eqrW In both cases there's basically a call to "delete nullptr" that doesn't get removed. I don't think this falls on libstdc++, rather than on the optimizer?
next prev parent reply other threads:[~2021-09-08 15:08 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-09-06 17:34 [Bug c++/102221] New: " dangelog at gmail dot com 2021-09-08 9:37 ` [Bug libstdc++/102221] " redi at gcc dot gnu.org 2021-09-08 15:08 ` dangelog at gmail dot com [this message] 2021-09-08 20:00 ` redi at gcc dot gnu.org 2021-09-08 20:21 ` redi at gcc dot gnu.org 2021-09-09 15:06 ` dangelog at gmail dot com 2021-12-09 16:31 ` dangelog at gmail dot com 2021-12-23 9:18 ` pinskia at gcc dot gnu.org
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