https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108583
--- Comment #29 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Tamar Christina <tnfch...@gcc.gnu.org>: https://gcc.gnu.org/g:81fd62d1378b7ddc1fa0967cbddcdcdcdd2d8d8c commit r13-6619-g81fd62d1378b7ddc1fa0967cbddcdcdcdd2d8d8c Author: Tamar Christina <tamar.christ...@arm.com> Date: Sun Mar 12 18:42:04 2023 +0000 middle-end: Implement preferred_div_as_shifts_over_mult [PR108583] This now implements a hook preferred_div_as_shifts_over_mult that indicates whether a target prefers that the vectorizer decomposes division as shifts rather than multiplication when possible. In order to be able to use this we need to check whether the current precision has enough bits to do the operation without any of the additions overflowing. We use range information to determine this and only do the operation if we're sure am overflow won't occur. This now uses ranger to do this range check. This seems to work better than vect_get_range_info which uses range_query, but I have not switched the interface of vect_get_range_info over in this PR fix. As Andy said before initializing a ranger instance is cheap but not free, and if the intention is to call it often during a pass it should be instantiated at pass startup and passed along to the places that need it. This is a big refactoring and doesn't seem right to do in this PR. But we should in GCC 14. Currently we only instantiate it after a long series of much cheaper checks. gcc/ChangeLog: PR target/108583 * target.def (preferred_div_as_shifts_over_mult): New. * doc/tm.texi.in: Document it. * doc/tm.texi: Regenerate. * targhooks.cc (default_preferred_div_as_shifts_over_mult): New. * targhooks.h (default_preferred_div_as_shifts_over_mult): New. * tree-vect-patterns.cc (vect_recog_divmod_pattern): Use it. gcc/testsuite/ChangeLog: PR target/108583 * gcc.dg/vect/vect-div-bitmask-4.c: New test. * gcc.dg/vect/vect-div-bitmask-5.c: New test.
