https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119431
Bug ID: 119431
Summary: Missed strlen when cmp to NUL forwards with increments
Product: gcc
Version: 14.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: kaelfandrew at gmail dot com
Target Milestone: ---
Created attachment 60854
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=60854&action=edit
C code
When trying to emulate strlen by checking NUL forwards in increments, f1() does
not optimize to f0().
gcc -v
========
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/14/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-pc-linux-gnu
Configured with:
/var/tmp/portage/sys-devel/gcc-14.2.1_p20241221/work/gcc-14-20241221/configure
--host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --prefix=/usr
--bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/14
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/14/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/14
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/14/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/14/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/14/include/g++-v14
--disable-silent-rules --disable-dependency-tracking
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/14/python
--enable-languages=c,c++ --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
14.2.1_p20241221 p7' --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-offload-defaulted --enable-offload-targets=nvptx-none --enable-libgomp
--disable-libssp --disable-libada --enable-cet --disable-systemtap
--disable-valgrind-annotations --disable-vtable-verify --disable-libvtv
--with-zstd --with-isl --disable-isl-version-check --enable-default-pie
--enable-host-pie --enable-host-bind-now --enable-default-ssp
--disable-fixincludes --with-build-config='bootstrap-lto bootstrap-cet'
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 14.2.1 20241221 (Gentoo 14.2.1_p20241221 p7)
