https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116140
--- Comment #13 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Alex Coplan <acop...@gcc.gnu.org>: https://gcc.gnu.org/g:3fd07d4f04f43816a038daf9b16c6d5bf2e96c9b commit r15-3586-g3fd07d4f04f43816a038daf9b16c6d5bf2e96c9b Author: Alex Coplan <alex.cop...@arm.com> Date: Fri Aug 2 09:56:07 2024 +0100 libstdc++: Restore unrolling in std::find using pragma [PR116140] Together with the preparatory compiler patches, this patch restores unrolling in std::__find_if, but this time relying on the compiler to do it by using: #pragma GCC unroll 4 which should restore the majority of the regression relative to the hand-unrolled version while still being vectorizable with WIP alignment peeling enhancements. On Neoverse V1 with LTO, this reduces the regression in xalancbmk (from SPEC CPU 2017) from 5.8% to 1.7% (restoring ~71% of the lost performance). libstdc++-v3/ChangeLog: PR libstdc++/116140 * include/bits/stl_algobase.h (std::__find_if): Add #pragma to request GCC to unroll the loop.
