https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115192
--- Comment #12 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-14 branch has been updated by Richard Sandiford <rsand...@gcc.gnu.org>: https://gcc.gnu.org/g:36575f5fe491d86b6851ff3f47cbfb7dad0fc8ae commit r14-10263-g36575f5fe491d86b6851ff3f47cbfb7dad0fc8ae Author: Richard Sandiford <richard.sandif...@arm.com> Date: Fri May 31 08:22:55 2024 +0100 vect: Fix access size alignment assumption [PR115192] create_intersect_range_checks checks whether two access ranges a and b are alias-free using something equivalent to: end_a <= start_b || end_b <= start_a It has two ways of doing this: a "vanilla" way that calculates the exact exclusive end pointers, and another way that uses the last inclusive aligned pointers (and changes the comparisons accordingly). The comment for the latter is: /* Calculate the minimum alignment shared by all four pointers, then arrange for this alignment to be subtracted from the exclusive maximum values to get inclusive maximum values. This "- min_align" is cumulative with a "+ access_size" in the calculation of the maximum values. In the best (and common) case, the two cancel each other out, leaving us with an inclusive bound based only on seg_len. In the worst case we're simply adding a smaller number than before. The problem is that the associated code implicitly assumed that the access size was a multiple of the pointer alignment, and so the alignment could be carried over to the exclusive end pointer. The testcase started failing after g:9fa5b473b5b8e289b6542 because that commit improved the alignment information for the accesses. gcc/ PR tree-optimization/115192 * tree-data-ref.cc (create_intersect_range_checks): Take the alignment of the access sizes into account. gcc/testsuite/ PR tree-optimization/115192 * gcc.dg/vect/pr115192.c: New test. (cherry picked from commit a0fe4fb1c8d7804515845dd5d2a814b3c7a1ccba)
