[Bug tree-optimization/114872] [13/14/15 Regression] Miscompilation with -O2 after commit r13-8037

["slyfox at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114872

--- Comment #17 from Sergei Trofimovich <slyfox at gcc dot gnu.org> ---
> 1) attach your *.s file and state which exact compiler you used (revision)

Generate code first:

https://slyfox.uni.cx/b/gcc/PR114872/d.tar.gz (4MB, does not fit on bugzilla's
1MB limit)

is the archive of source files from sage-10.3:
- element.c: original unpreprocessed file
- element.c.c: preprocessed file
- element.S: assembly file (-S)
- element-verbose.S: assembly file (-S -fverbose-asm, has compiler options)

Compiler:

# gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/13/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with:
/dev/shm/portage/sys-devel/gcc-13.2.1_p20240503/work/gcc-13-20240503/configure
--host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --prefix=/usr
--bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/13
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/13/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/13
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/13/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/13/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/13/include/g++-v13
--disable-silent-rules --disable-dependency-tracking
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/13/python
--enable-languages=c,c++,fortran --enable-obsolete --enable-secureplt
--disable-werror --with-system-zlib --enable-nls --without-included-gettext
--disable-libunwind-exceptions --enable-checking=release
--with-bugurl=https://bugs.gentoo.org/ --with-pkgversion='Gentoo
13.2.1_p20240503 p15' --with-gcc-major-version-only --enable-libstdcxx-time
--enable-lto --disable-libstdcxx-pch --enable-shared --enable-threads=posix
--enable-__cxa_atexit --enable-clocale=gnu --enable-multilib
--with-multilib-list=m32,m64 --disable-fixed-point --enable-targets=all
--enable-libgomp --disable-libssp --disable-libada --disable-cet
--disable-systemtap --disable-valgrind-annotations --disable-vtable-verify
--disable-libvtv --without-zstd --without-isl --enable-default-pie
--enable-default-ssp --disable-fixincludes
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 13.2.1 20240503 (Gentoo 13.2.1_p20240503 p15)

Note: it's a weekly snapshot of 20240503 with --enable-default-ssp. I think
it's a r13-8684-g704b15e277a879.

The compiler also has a few distro-specific patches on top:
https://gitweb.gentoo.org/proj/gcc-patches.git/tree/13.2.0/gentoo. Most of them
should not affect code generation too much, but some like
22_all_default_ssp-buffer-size.patch and
84_all_x86_PR110792-Early-clobber-issues-with-rot32di2.patch might.