[Bug tree-optimization/92526] [10 Regression] ICE in vect_enhance_data_refs_alignment, at tree-vect-data-refs.c:2274 since r278244

[rsandifo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92526

--- Comment #2 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> ---
Author: rsandifo
Date: Thu Nov 21 17:45:36 2019
New Revision: 278592

URL: https://gcc.gnu.org/viewcvs?rev=278592&root=gcc&view=rev
Log:
Reject versioning for alignment with different masks (PR 92526)

Allowing mixed vector sizes broke the assumption in the following assert,
since it's now possible for different accesses to require different
levels of alignment:

              /* FORNOW: use the same mask to test all potentially unaligned
                 references in the loop.  The vectorizer currently supports
                 a single vector size, see the reference to
                 GET_MODE_NUNITS (TYPE_MODE (vectype)) where the
                 vectorization factor is computed.  */
              gcc_assert (!LOOP_VINFO_PTR_MASK (loop_vinfo)
                          || LOOP_VINFO_PTR_MASK (loop_vinfo) == mask);

I guess we could try to over-align smaller accesses so that all
of them are consistent, or try to support multiple alignment masks,
but for now the easiest fix seems to be to turn the assert into a
bail-out check.

2019-11-21  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
        PR tree-optimization/92526
        * tree-vect-data-refs.c (vect_enhance_data_refs_alignment): Reject
        versioning for alignment if the accesses do not have a consistent
        mask, rather than asserting that the masks are consistent.

gcc/testsuite/
        PR tree-optimization/92526
        * gcc.target/aarch64/pr92526.c: New test.

Added:
    trunk/gcc/testsuite/gcc.target/aarch64/pr92526.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-vect-data-refs.c