[Bug tree-optimization/107835] [13 Regression] ICE in build2, at tree.cc:5020 since r13-254-gdd3c7873a61019e9

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107835

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:7716ee1e90412f785cba20acffd59fc7461302cb

commit r13-4405-g7716ee1e90412f785cba20acffd59fc7461302cb
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Nov 30 11:44:27 2022 +0100

    tree-chrec: Fix up ICE on pointer multiplication [PR107835]

    r13-254-gdd3c7873a61019e9 added an optimization for {a, +, a} (x-1),
    but as can be seen on the following testcase, the way it is written
    where chrec_fold_multiply is called with type doesn't work for pointers:
                 res = build_int_cst (TREE_TYPE (x), 1);
                 res = chrec_fold_plus (TREE_TYPE (x), x, res);
                 res = chrec_convert_rhs (type, res, NULL);
                 res = chrec_fold_multiply (type, chrecr, res);
    while what we were doing before and what is still used if the condition
    doesn't match is fine:
                 res = chrec_convert_rhs (TREE_TYPE (chrecr), x, NULL);
                 res = chrec_fold_multiply (TREE_TYPE (chrecr), chrecr, res);
                 res = chrec_fold_plus (type, CHREC_LEFT (chrec), res);
    because it performs chrec_fold_multiply on TREE_TYPE (chrecr) and converts
    only afterwards.

    I think the easiest fix is to ignore the new path for pointer types.

    2022-11-30  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/107835
            * tree-chrec.cc (chrec_apply): Don't handle "{a, +, a} (x-1)"
            as "a*x" if type is a pointer type.

            * gcc.c-torture/compile/pr107835.c: New test.