https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104912
--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Richard Biener <rgue...@gcc.gnu.org>: https://gcc.gnu.org/g:ac8340ee4d1e65f3fd41c547b16895875f4aefa7 commit r12-8132-gac8340ee4d1e65f3fd41c547b16895875f4aefa7 Author: Richard Biener <rguent...@suse.de> Date: Mon Mar 21 14:08:25 2022 +0100 tree-optimization/104912 - ensure cost model is checked first The following makes sure that when we build the versioning condition for vectorization including the cost model check, we check for the cost model and branch over other versioning checks. That is what the cost modeling assumes, since the cost model check is the only one accounted for in the scalar outside cost. Currently we emit all checks as straight-line code combined with bitwise ops which can result in surprising ordering of checks in the final assembly. Since loop_version accepts only a single versioning condition the splitting is done after the fact. The result is a 1.5% speedup of 416.gamess on x86_64 when compiling with -Ofast and tuning for generic or skylake. That's not enough to recover from the slowdown when vectorizing but it now cuts off the expensive alias versioning test. 2022-03-21 Richard Biener <rguent...@suse.de> PR tree-optimization/104912 * tree-vect-loop-manip.cc (vect_loop_versioning): Split the cost model check to a separate BB to make sure it is checked first and not combined with other version checks.
