https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115438
--- Comment #10 from GCC 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:a54aa75ab30eb1a176ceaded507113252df24878 commit r15-5784-ga54aa75ab30eb1a176ceaded507113252df24878 Author: Richard Biener <rguent...@suse.de> Date: Fri Nov 29 12:14:24 2024 +0100 tree-optimization/115438 - SLP reduction vect vs. bwaves 503.bwaves_r shows a case where the non-SLP optimization of performing the reduction adjustment with the initial value as part of the epilogue rather than including it as part of the initial vector value. It allows to break a critical dependence path. The following restores this ability for single-lane SLP. On Zen2 this turns a 2.5% regression from GCC 14 into a 2.5% improvement. PR tree-optimization/115438 * tree-vect-loop.cc (vect_transform_cycle_phi): For SLP also try to do the reduction adjustment by the initial value in the epilogue.
