[Bug middle-end/112733] [14 Regression] ICE: Segmentation fault in wide-int.cc during GIMPLE pass: sccp

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112733

--- Comment #17 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:4bf040fcd23aaa7d8c4873d1170776ab117bc213

commit r12-10055-g4bf040fcd23aaa7d8c4873d1170776ab117bc213
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Nov 29 12:26:50 2023 +0100

    fold-const: Fix up multiple_of_p [PR112733]

    We ICE on the following testcase when wi::multiple_of_p is called on
    widest_int 1 and -128 with UNSIGNED.  I still need to work on the
    actual wide-int.cc issue, the latest patch attached to the PR regressed
    bitint-{38,39}.c, so will need to debug that, but there is a clear bug
    on the fold-const.cc side as well - widest_int is a signed representation
    by definition, using UNSIGNED with it certainly doesn't match what was
    intended, because -128 as the second operand effectively means unsigned
    131072 bit 0xfffff............ffff80 integer, not the signed char -128
    that appeared in the source.

    In the INTEGER_CST case a few lines above this we already use
        case INTEGER_CST:
          if (TREE_CODE (bottom) != INTEGER_CST || integer_zerop (bottom))
            return false;
          return wi::multiple_of_p (wi::to_widest (top), wi::to_widest
(bottom),
                                    SIGNED);
    so I think using SIGNED with widest_int is best there (compared to the
    other choices in the PR).

    2023-11-29  Jakub Jelinek  <jakub@redhat.com>

            PR middle-end/112733
            * fold-const.cc (multiple_of_p): Pass SIGNED rather than
            UNSIGNED for wi::multiple_of_p on widest_int arguments.

            * gcc.dg/pr112733.c: New test.

    (cherry picked from commit 5c95bf945c632925efba86dd5dceccdb9da8884c)