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From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/108846] std::copy, std::copy_n and std::copy_backward on potentially overlapping subobjects Date: Tue, 28 Feb 2023 09:50:04 +0000 [thread overview] Message-ID: <bug-108846-4-CATRxWZxXb@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-108846-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108846 --- Comment #19 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jonathan Wakely <redi@gcc.gnu.org>: https://gcc.gnu.org/g:822a11a1e642e0abe92a996e7033a5066905a447 commit r13-6372-g822a11a1e642e0abe92a996e7033a5066905a447 Author: Jonathan Wakely <jwakely@redhat.com> Date: Sat Feb 25 14:28:36 2023 +0000 libstdc++: Do not use memmove for 1-element ranges [PR108846] This avoids overwriting tail padding when algorithms like std::copy are used to write a single value through a pointer to a base subobject. The pointer arithmetic on a Base* is valid for N==1, but the copy/move operation needs to be done using assignment, not a memmove or memcpy of sizeof(Base) bytes. Instead of putting a check for N==1 in all of copy, copy_n, move etc. this adds it to the __copy_move and __copy_move_backward partial specializations used for trivially copyable types. When N==1 those partial specializations dispatch to new static member functions of the partial specializations for non-trivial types, so that a copy/move assignment is done appropriately for the _IsMove constant. libstdc++-v3/ChangeLog: PR libstdc++/108846 * include/bits/stl_algobase.h (__copy_move<false, false, RA>) Add __assign_one static member function. (__copy_move<true, false, RA>): Likewise. (__copy_move<IsMove, true, RA>): Do not use memmove for a single value. (__copy_move_backward<IsMove, true, RA>): Likewise. * testsuite/25_algorithms/copy/108846.cc: New test. * testsuite/25_algorithms/copy_backward/108846.cc: New test. * testsuite/25_algorithms/copy_n/108846.cc: New test. * testsuite/25_algorithms/move/108846.cc: New test. * testsuite/25_algorithms/move_backward/108846.cc: New test.
next prev parent reply other threads:[~2023-02-28 9:50 UTC|newest] Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-02-18 21:22 [Bug libstdc++/108846] New: std::copy, std::copy_n " arthur.j.odwyer at gmail dot com 2023-02-18 21:55 ` [Bug libstdc++/108846] " pinskia at gcc dot gnu.org 2023-02-18 21:58 ` pinskia at gcc dot gnu.org 2023-02-18 22:00 ` pinskia at gcc dot gnu.org 2023-02-20 8:38 ` de34 at live dot cn 2023-02-20 23:42 ` dangelog at gmail dot com 2023-02-21 1:58 ` de34 at live dot cn 2023-02-21 7:21 ` [Bug libstdc++/108846] std::copy, std::copy_n and std::copy_backward " pinskia at gcc dot gnu.org 2023-02-23 17:20 ` redi at gcc dot gnu.org 2023-02-23 17:25 ` redi at gcc dot gnu.org 2023-02-23 17:27 ` redi at gcc dot gnu.org 2023-02-23 17:29 ` arthur.j.odwyer at gmail dot com 2023-02-24 19:31 ` dangelog at gmail dot com 2023-02-25 9:06 ` redi at gcc dot gnu.org 2023-02-25 9:07 ` redi at gcc dot gnu.org 2023-02-25 11:40 ` dangelog at gmail dot com 2023-02-25 14:13 ` redi at gcc dot gnu.org 2023-02-25 14:16 ` redi at gcc dot gnu.org 2023-02-25 14:19 ` redi at gcc dot gnu.org 2023-02-25 14:29 ` redi at gcc dot gnu.org 2023-02-28 9:50 ` cvs-commit at gcc dot gnu.org [this message] 2023-03-02 10:49 ` dangelog at gmail dot com 2023-03-02 11:19 ` redi at gcc dot gnu.org 2023-04-20 13:50 ` redi at gcc dot gnu.org 2023-04-20 14:12 ` arthur.j.odwyer at gmail dot com 2023-04-20 17:10 ` redi at gcc dot gnu.org 2023-04-20 17:11 ` redi at gcc dot gnu.org 2024-03-18 14:05 ` cvs-commit at gcc dot gnu.org 2024-03-18 14:13 ` redi at gcc dot gnu.org
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