https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110879
--- Comment #1 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jonathan Wakely <r...@gcc.gnu.org>: https://gcc.gnu.org/g:419c423d3aeca754e47e1ce1bf707735603a90a3 commit r14-3627-g419c423d3aeca754e47e1ce1bf707735603a90a3 Author: Vladimir Palevich <palevic...@gmail.com> Date: Wed Aug 9 01:34:05 2023 +0300 libstdc++: fix memory clobbering in std::vector [PR110879] Fix ordering to prevent clobbering of class members by a call to deallocate in _M_realloc_insert and _M_default_append. Because of recent changes in _M_realloc_insert and _M_default_append, calls to deallocate were ordered after assignment to class members of std::vector (in the guard destructor), which is causing said members to be call-clobbered. This is preventing further optimization, the compiler is unable to move memory read out of a hot loop in this case. This patch reorders the call to before assignments by putting guard in its own block. Plus a new testsuite for this case. I'm not very happy with the new testsuite, but I don't know how to properly test this. PR libstdc++/110879 libstdc++-v3/ChangeLog: * include/bits/vector.tcc (_M_realloc_insert): End guard lifetime just before assignment to class members. (_M_default_append): Likewise. gcc/testsuite/ChangeLog: * g++.dg/pr110879.C: New test. Signed-off-by: Vladimir Palevich <palevic...@gmail.com>
