https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99954
--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-10 branch has been updated by Richard Biener <rgue...@gcc.gnu.org>: https://gcc.gnu.org/g:ee16f803357725df96e8c232b8066d9db3ec16a8 commit r10-9768-gee16f803357725df96e8c232b8066d9db3ec16a8 Author: Richard Biener <rguent...@suse.de> Date: Wed Apr 7 13:17:05 2021 +0200 tree-optimization/99954 - fix loop distribution memcpy classification This fixes bogus classification of a copy as memcpy. We cannot use plain dependence analysis to decide between memcpy and memmove when it computes no dependence. Instead we have to try harder later which the patch does for the gcc.dg/tree-ssa/ldist-24.c testcase by resorting to tree-affine to compute the difference between src and dest and compare against the copy size. 2021-04-07 Richard Biener <rguent...@suse.de> PR tree-optimization/99954 * tree-loop-distribution.c: Include tree-affine.h. (generate_memcpy_builtin): Try using tree-affine to prove non-overlap. (loop_distribution::classify_builtin_ldst): Always classify as PKIND_MEMMOVE. * gcc.dg/torture/pr99954.c: New testcase. (cherry picked from commit c01ae2ab6b227e21835d128c90e974dce4604be9)