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| author | Vladimir Palevich <palevichva@gmail.com> | 2023-08-09 01:34:05 +0300 |
|---|---|---|
| committer | Jonathan Wakely <jwakely@redhat.com> | 2023-09-01 16:01:23 +0100 |
| commit | 419c423d3aeca754e47e1ce1bf707735603a90a3 (patch) | |
| tree | 85566082042c25882b51e6b26feacac150da81e4 /libcpp | |
| parent | 283994cba687e0746f9a1018bae2c41291e362ff (diff) | |
| download | gcc-419c423d3aeca754e47e1ce1bf707735603a90a3.zip gcc-419c423d3aeca754e47e1ce1bf707735603a90a3.tar.gz gcc-419c423d3aeca754e47e1ce1bf707735603a90a3.tar.bz2 | |
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 <palevichva@gmail.com>
Diffstat (limited to 'libcpp')
0 files changed, 0 insertions, 0 deletions