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* [Bug c++/115399] New: std::tr2::dynamic_bitset shift behaves differently from std::bitset @ 2024-06-08 21:21 adamant.pwn at gmail dot com 2024-06-08 22:17 ` [Bug libstdc++/115399] " adamant.pwn at gmail dot com ` (5 more replies) 0 siblings, 6 replies; 7+ messages in thread From: adamant.pwn at gmail dot com @ 2024-06-08 21:21 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115399 Bug ID: 115399 Summary: std::tr2::dynamic_bitset shift behaves differently from std::bitset Product: gcc Version: 14.1.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: adamant.pwn at gmail dot com Target Milestone: --- Target: x86-64 Linux Build: 20240522 Posting a bug on behalf of someone who didn't manage to create an account at GCC bugzilla due to automatic registration being disabled... The bug is due to the line https://github.com/gcc-mirror/gcc/blob/master/libstdc%2B%2B-v3/include/tr2/dynamic_bitset.tcc#L63 being commented out in dynamic_bitset implementation (unlike std::bitset, where it is present). Uncommenting it should fix the problem. A simple example program to highlight the discrepancy: #include <iostream> #include <bitset> #include <tr2/dynamic_bitset> int main() { std::tr2::dynamic_bitset<> test(91); test[50] = true; std::cout << test << "\n"; std::cout << (test << 78) << "\n"; std::cout << "\n"; std::bitset<91> test2; test2[50] = true; std::cout << test2 << "\n"; std::cout << (test2 << 78) << "\n"; } Output: 0000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000 0000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000 0000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug libstdc++/115399] std::tr2::dynamic_bitset shift behaves differently from std::bitset 2024-06-08 21:21 [Bug c++/115399] New: std::tr2::dynamic_bitset shift behaves differently from std::bitset adamant.pwn at gmail dot com @ 2024-06-08 22:17 ` adamant.pwn at gmail dot com 2024-06-08 22:50 ` pinskia at gcc dot gnu.org ` (4 subsequent siblings) 5 siblings, 0 replies; 7+ messages in thread From: adamant.pwn at gmail dot com @ 2024-06-08 22:17 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115399 --- Comment #1 from Oleksandr Kulkov <adamant.pwn at gmail dot com> --- The bug also affects right shift for a similar reason (https://github.com/gcc-mirror/gcc/blob/master/libstdc%2B%2B-v3/include/tr2/dynamic_bitset.tcc#L91): #include <iostream> #include <bitset> #include <tr2/dynamic_bitset> #include <boost/dynamic_bitset.hpp> int main() { std::tr2::dynamic_bitset<> test(128); for (int i = 64; i < 128; i++) test[i] = 1; std::cout << test << "\n"; std::cout << (test >> 65) << "\n\n"; boost::dynamic_bitset<> test2(128); for (int i = 64; i < 128; i++) test2[i] = 1; std::cout << test2 << "\n"; std::cout << (test2 >> 65) << "\n\n"; std::bitset<128> test3; for (int i = 64; i < 128; i++) test3[i] = 1; std::cout << test3 << "\n"; std::cout << (test3 >> 65) << "\n\n"; } Output: 11111111111111111111111111111111111111111111111111111111111111110000000000000000000000000000000000000000000000000000000000000000 11111111111111111111111111111111111111111111111111111111111111110111111111111111111111111111111111111111111111111111111111111111 11111111111111111111111111111111111111111111111111111111111111110000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000000000000111111111111111111111111111111111111111111111111111111111111111 11111111111111111111111111111111111111111111111111111111111111110000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000000000000111111111111111111111111111111111111111111111111111111111111111 See also https://github.com/emsr/tr2/issues/1. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug libstdc++/115399] std::tr2::dynamic_bitset shift behaves differently from std::bitset 2024-06-08 21:21 [Bug c++/115399] New: std::tr2::dynamic_bitset shift behaves differently from std::bitset adamant.pwn at gmail dot com 2024-06-08 22:17 ` [Bug libstdc++/115399] " adamant.pwn at gmail dot com @ 2024-06-08 22:50 ` pinskia at gcc dot gnu.org 2024-06-10 8:46 ` redi at gcc dot gnu.org ` (3 subsequent siblings) 5 siblings, 0 replies; 7+ messages in thread From: pinskia at gcc dot gnu.org @ 2024-06-08 22:50 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115399 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- See Also| |https://gcc.gnu.org/bugzill | |a/show_bug.cgi?id=114498 --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Note I think std::tr2 should be deprecated in a similar way as std::tr1 is being considered. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug libstdc++/115399] std::tr2::dynamic_bitset shift behaves differently from std::bitset 2024-06-08 21:21 [Bug c++/115399] New: std::tr2::dynamic_bitset shift behaves differently from std::bitset adamant.pwn at gmail dot com 2024-06-08 22:17 ` [Bug libstdc++/115399] " adamant.pwn at gmail dot com 2024-06-08 22:50 ` pinskia at gcc dot gnu.org @ 2024-06-10 8:46 ` redi at gcc dot gnu.org 2024-06-10 11:38 ` redi at gcc dot gnu.org ` (2 subsequent siblings) 5 siblings, 0 replies; 7+ messages in thread From: redi at gcc dot gnu.org @ 2024-06-10 8:46 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115399 Jonathan Wakely <redi at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Last reconfirmed| |2024-06-10 Ever confirmed|0 |1 Status|UNCONFIRMED |NEW --- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> --- The tr2 extensions never even got proposed for standardization and are not in any ISO document at all. They're not well tested and nobody uses them. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug libstdc++/115399] std::tr2::dynamic_bitset shift behaves differently from std::bitset 2024-06-08 21:21 [Bug c++/115399] New: std::tr2::dynamic_bitset shift behaves differently from std::bitset adamant.pwn at gmail dot com ` (2 preceding siblings ...) 2024-06-10 8:46 ` redi at gcc dot gnu.org @ 2024-06-10 11:38 ` redi at gcc dot gnu.org 2024-06-12 14:07 ` cvs-commit at gcc dot gnu.org 2024-06-12 15:57 ` redi at gcc dot gnu.org 5 siblings, 0 replies; 7+ messages in thread From: redi at gcc dot gnu.org @ 2024-06-10 11:38 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115399 Jonathan Wakely <redi at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |wrong-code Assignee|unassigned at gcc dot gnu.org |redi at gcc dot gnu.org Status|NEW |ASSIGNED ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug libstdc++/115399] std::tr2::dynamic_bitset shift behaves differently from std::bitset 2024-06-08 21:21 [Bug c++/115399] New: std::tr2::dynamic_bitset shift behaves differently from std::bitset adamant.pwn at gmail dot com ` (3 preceding siblings ...) 2024-06-10 11:38 ` redi at gcc dot gnu.org @ 2024-06-12 14:07 ` cvs-commit at gcc dot gnu.org 2024-06-12 15:57 ` redi at gcc dot gnu.org 5 siblings, 0 replies; 7+ messages in thread From: cvs-commit at gcc dot gnu.org @ 2024-06-12 14:07 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115399 --- Comment #4 from GCC 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:bd3a312728fbf8c35a09239b9180269f938f872e commit r15-1213-gbd3a312728fbf8c35a09239b9180269f938f872e Author: Jonathan Wakely <jwakely@redhat.com> Date: Mon Jun 10 14:08:16 2024 +0100 libstdc++: Fix std::tr2::dynamic_bitset shift operations [PR115399] The shift operations for dynamic_bitset fail to zero out words where the non-zero bits were shifted to a completely different word. For a right shift we don't need to sanitize the unused bits in the high word, because we know they were already clear and a right shift doesn't change that. libstdc++-v3/ChangeLog: PR libstdc++/115399 * include/tr2/dynamic_bitset (operator>>=): Remove redundant call to _M_do_sanitize. * include/tr2/dynamic_bitset.tcc (_M_do_left_shift): Zero out low bits in words that should no longer be populated. (_M_do_right_shift): Likewise for high bits. * testsuite/tr2/dynamic_bitset/pr115399.cc: New test. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug libstdc++/115399] std::tr2::dynamic_bitset shift behaves differently from std::bitset 2024-06-08 21:21 [Bug c++/115399] New: std::tr2::dynamic_bitset shift behaves differently from std::bitset adamant.pwn at gmail dot com ` (4 preceding siblings ...) 2024-06-12 14:07 ` cvs-commit at gcc dot gnu.org @ 2024-06-12 15:57 ` redi at gcc dot gnu.org 5 siblings, 0 replies; 7+ messages in thread From: redi at gcc dot gnu.org @ 2024-06-12 15:57 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115399 Jonathan Wakely <redi at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Resolution|--- |FIXED Status|ASSIGNED |RESOLVED Target Milestone|--- |15.0 --- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> --- Fixed on trunk. I'll probably backport it to the release branches at some point. ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2024-06-12 15:57 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2024-06-08 21:21 [Bug c++/115399] New: std::tr2::dynamic_bitset shift behaves differently from std::bitset adamant.pwn at gmail dot com 2024-06-08 22:17 ` [Bug libstdc++/115399] " adamant.pwn at gmail dot com 2024-06-08 22:50 ` pinskia at gcc dot gnu.org 2024-06-10 8:46 ` redi at gcc dot gnu.org 2024-06-10 11:38 ` redi at gcc dot gnu.org 2024-06-12 14:07 ` cvs-commit at gcc dot gnu.org 2024-06-12 15:57 ` redi at gcc dot gnu.org
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