https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109791
Bug ID: 109791
Summary: -Wstringop-overflow warning with -O3 and
_GLIBCXX_USE_CXX11_ABI=0
Product: gcc
Version: 12.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: szhong at perforce dot com
Target Milestone: ---
Created attachment 55033
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55033&action=edit
preprocessed file
It appears -fvect-cost-model=dynamic from the -O3 flag is causing the
-Wstringop-overflow warning.
testcase:
#include <algorithm>
#include <string>
int main()
{
char str[] = " a";
do {
std::string input(str, sizeof(str) / sizeof(*str));
}
while (std::next_permutation(str, str + sizeof(str) / sizeof(*str)));
return 0;
}
$ g++ -v -save-temps -m64 -D_GLIBCXX_USE_CXX11_ABI=0 -O2
-fvect-cost-model=dynamic no_cxx11_abi.cpp
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/opt/rh/gcc-toolset-12/root/usr/libexec/gcc/x86_64-redhat-linux/12/lto-wrapper
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Target: x86_64-redhat-linux
Configured with: ../configure --enable-bootstrap
--enable-languages=c,c++,fortran,lto --prefix=/opt/rh/gcc-toolset-12/root/usr
--mandir=/opt/rh/gcc-toolset-12/root/usr/share/man
--infodir=/opt/rh/gcc-toolset-12/root/usr/share/info
--with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared
--enable-threads=posix --enable-checking=release --enable-multilib
--with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions
--enable-gnu-unique-object --enable-linker-build-id
--with-gcc-major-version-only --enable-libstdcxx-backtrace
--with-linker-hash-style=gnu --enable-plugin --enable-initfini-array
--with-isl=/builddir/build/BUILD/gcc-12.1.1-20220628/obj-x86_64-redhat-linux/isl-install
--enable-offload-targets=nvptx-none --without-cuda-driver
--enable-offload-defaulted --enable-gnu-indirect-function --enable-cet
--with-tune=generic --with-arch_64=x86-64-v2 --with-arch_32=x86-64
--build=x86_64-redhat-linux --with-build-config=bootstrap-lto
--enable-link-serialization=1
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 12.1.1 20220628 (Red Hat 12.1.1-3) (GCC)
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-m64' '-D' '_GLIBCXX_USE_CXX11_ABI=0'
'-O2' '-fvect-cost-model=dynamic' '-shared-libgcc' '-mtune=generic'
'-march=x86-64-v2' '-dumpdir' 'a-'
/opt/rh/gcc-toolset-12/root/usr/libexec/gcc/x86_64-redhat-linux/12/cc1plus -E
-quiet -v -D_GNU_SOURCE -D _GLIBCXX_USE_CXX11_ABI=0 no_cxx11_abi.cpp -m64
-mtune=generic -march=x86-64-v2 -fvect-cost-model=dynamic -O2 -fpch-preprocess
-o a-no_cxx11_abi.ii
ignoring nonexistent directory
"/opt/rh/gcc-toolset-12/root/usr/lib/gcc/x86_64-redhat-linux/12/include-fixed"
ignoring nonexistent directory
"/opt/rh/gcc-toolset-12/root/usr/lib/gcc/x86_64-redhat-linux/12/../../../../x86_64-redhat-linux/include"
#include "..." search starts here:
#include <...> search starts here:
/opt/rh/gcc-toolset-12/root/usr/lib/gcc/x86_64-redhat-linux/12/../../../../include/c++/12
/opt/rh/gcc-toolset-12/root/usr/lib/gcc/x86_64-redhat-linux/12/../../../../include/c++/12/x86_64-redhat-linux
/opt/rh/gcc-toolset-12/root/usr/lib/gcc/x86_64-redhat-linux/12/../../../../include/c++/12/backward
/opt/rh/gcc-toolset-12/root/usr/lib/gcc/x86_64-redhat-linux/12/include
/usr/local/include
/opt/rh/gcc-toolset-12/root/usr/include
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End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-m64' '-D' '_GLIBCXX_USE_CXX11_ABI=0'
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'-march=x86-64-v2' '-dumpdir' 'a-'
/opt/rh/gcc-toolset-12/root/usr/libexec/gcc/x86_64-redhat-linux/12/cc1plus
-fpreprocessed a-no_cxx11_abi.ii -quiet -dumpdir a- -dumpbase no_cxx11_abi.cpp
-dumpbase-ext .cpp -m64 -mtune=generic -march=x86-64-v2 -O2 -version
-fvect-cost-model=dynamic -o a-no_cxx11_abi.s
GNU C++17 (GCC) version 12.1.1 20220628 (Red Hat 12.1.1-3)
(x86_64-redhat-linux)
compiled by GNU C version 12.1.1 20220628 (Red Hat 12.1.1-3), GMP
version 6.2.0, MPFR version 4.1.0-p9, MPC version 1.2.1, isl version
isl-0.18-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C++17 (GCC) version 12.1.1 20220628 (Red Hat 12.1.1-3)
(x86_64-redhat-linux)
compiled by GNU C version 12.1.1 20220628 (Red Hat 12.1.1-3), GMP
version 6.2.0, MPFR version 4.1.0-p9, MPC version 1.2.1, isl version
isl-0.18-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 4fe953bdd6603241811586d9fd73a7cb
In file included from
/opt/rh/gcc-toolset-12/root/usr/include/c++/12/bits/stl_pair.h:61,
from
/opt/rh/gcc-toolset-12/root/usr/include/c++/12/bits/stl_algobase.h:64,
from
/opt/rh/gcc-toolset-12/root/usr/include/c++/12/algorithm:60,
from no_cxx11_abi.cpp:1:
In function \u2018std::_Require<std::__not_<std::__is_tuple_like<_Tp> >,
std::is_move_constructible<_Tp>, std::is_move_assignable<_Tp> > std::swap(_Tp&,
_Tp&) [with _Tp = char]\u2019,
inlined from \u2018void std::iter_swap(_ForwardIterator1,
_ForwardIterator2) [with _ForwardIterator1 = char*; _ForwardIterator2 =
char*]\u2019 at
/opt/rh/gcc-toolset-12/root/usr/include/c++/12/bits/stl_algobase.h:182:11,
inlined from \u2018void std::__reverse(_RandomAccessIterator,
_RandomAccessIterator, random_access_iterator_tag) [with _RandomAccessIterator
= char*]\u2019 at
/opt/rh/gcc-toolset-12/root/usr/include/c++/12/bits/stl_algo.h:1107:18,
inlined from \u2018bool std::__next_permutation(_BidirectionalIterator,
_BidirectionalIterator, _Compare) [with _BidirectionalIterator = char*;
_Compare = __gnu_cxx::__ops::_Iter_less_iter]\u2019 at
/opt/rh/gcc-toolset-12/root/usr/include/c++/12/bits/stl_algo.h:2907:22,
inlined from \u2018bool std::next_permutation(_BIter, _BIter) [with _BIter
= char*]\u2019 at
/opt/rh/gcc-toolset-12/root/usr/include/c++/12/bits/stl_algo.h:2947:2,
inlined from \u2018int main()\u2019 at no_cxx11_abi.cpp:10:33:
/opt/rh/gcc-toolset-12/root/usr/include/c++/12/bits/move.h:205:11: warning:
writing 8 bytes into a region of size 2 [-Wstringop-overflow=]
205 | __a = _GLIBCXX_MOVE(__b);
| ~~~~^~~~~~~~~~~~~~~~
no_cxx11_abi.cpp: In function \u2018int main()\u2019:
no_cxx11_abi.cpp:6:10: note: at offset [1, 2] into destination object
\u2018str\u2019 of size 3
6 | char str[] = " a";
| ^~~
no_cxx11_abi.cpp:6:10: note: at offset [2, 3] into destination object
\u2018str\u2019 of size 3
In function \u2018std::_Require<std::__not_<std::__is_tuple_like<_Tp> >,
std::is_move_constructible<_Tp>, std::is_move_assignable<_Tp> > std::swap(_Tp&,
_Tp&) [with _Tp = char]\u2019,
inlined from \u2018void std::iter_swap(_ForwardIterator1,
_ForwardIterator2) [with _ForwardIterator1 = char*; _ForwardIterator2 =
char*]\u2019 at
/opt/rh/gcc-toolset-12/root/usr/include/c++/12/bits/stl_algobase.h:182:11,
inlined from \u2018void std::__reverse(_RandomAccessIterator,
_RandomAccessIterator, random_access_iterator_tag) [with _RandomAccessIterator
= char*]\u2019 at
/opt/rh/gcc-toolset-12/root/usr/include/c++/12/bits/stl_algo.h:1107:18,
inlined from \u2018bool std::__next_permutation(_BidirectionalIterator,
_BidirectionalIterator, _Compare) [with _BidirectionalIterator = char*;
_Compare = __gnu_cxx::__ops::_Iter_less_iter]\u2019 at
/opt/rh/gcc-toolset-12/root/usr/include/c++/12/bits/stl_algo.h:2907:22,
inlined from \u2018bool std::next_permutation(_BIter, _BIter) [with _BIter
= char*]\u2019 at
/opt/rh/gcc-toolset-12/root/usr/include/c++/12/bits/stl_algo.h:2947:2,
inlined from \u2018int main()\u2019 at no_cxx11_abi.cpp:10:33:
/opt/rh/gcc-toolset-12/root/usr/include/c++/12/bits/move.h:206:11: warning:
writing 8 bytes into a region of size 0 [-Wstringop-overflow=]
206 | __b = _GLIBCXX_MOVE(__tmp);
| ~~~~^~~~~~~~~~~~~~~~~~
no_cxx11_abi.cpp: In function \u2018int main()\u2019:
no_cxx11_abi.cpp:6:10: note: at offset 9223372036854775803 into destination
object \u2018str\u2019 of size 3
6 | char str[] = " a";
| ^~~
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-m64' '-D' '_GLIBCXX_USE_CXX11_ABI=0'
'-O2' '-fvect-cost-model=dynamic' '-shared-libgcc' '-mtune=generic'
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as -v --64 -o a-no_cxx11_abi.o a-no_cxx11_abi.s
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$ cat /etc/os-release
NAME="Red Hat Enterprise Linux"
VERSION="9.1 (Plow)"
ID="rhel"
ID_LIKE="fedora"
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REDHAT_SUPPORT_PRODUCT="Red Hat Enterprise Linux"
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