https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110979
--- Comment #3 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:798a880a0b1fed8a9e3b3e026dd8bd09314b7c38 commit r14-3149-g798a880a0b1fed8a9e3b3e026dd8bd09314b7c38 Author: Richard Biener <rguent...@suse.de> Date: Fri Aug 11 13:00:17 2023 +0200 tree-optimization/110979 - fold-left reduction and partial vectors When we vectorize fold-left reductions with partial vectors but no target operation available we use a vector conditional to force excess elements to zero. But that doesn't correctly preserve the sign of zero. The following patch disables partial vector support when we have to do that and also need to honor rounding modes other than round-to-nearest. When round-to-nearest is in effect and we have to preserve the sign of zero instead use negative zero for the excess elements. PR tree-optimization/110979 * tree-vect-loop.cc (vectorizable_reduction): For FOLD_LEFT_REDUCTION without target support make sure we don't need to honor signed zeros and sign dependent rounding. * gcc.dg/torture/pr110979.c: New testcase.
