[Bug tree-optimization/108355] [13/14 Regression] Dead Code Elimination Regression at -O2 since r13-2772-g9baee6181b4e42

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108355

--- Comment #7 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:938a419182f8c43bd1212ffb98f8aa6077cf8326

commit r14-8929-g938a419182f8c43bd1212ffb98f8aa6077cf8326
Author: Richard Biener <rguenther@suse.de>
Date:   Fri Feb 9 10:16:38 2024 +0100

    tree-optimization/113831 - wrong VN with structurally identical ref

    When we use get_ref_base_and_extent during VN and that ends up using
    global ranges to restrict the range of a ref we have to take care
    of not using the same expression in the hashtable as for a ref that
    could not use that global range.  The following attempts to ensure
    this by applying similar logic as get_ref_base_and_extent to
    copy_reference_ops_from_ref so they behave consistent.

            PR tree-optimization/113831
            PR tree-optimization/108355
            * tree-ssa-sccvn.cc (copy_reference_ops_from_ref): When
            we see variable array indices and get_ref_base_and_extent
            can resolve those to constants fix up the ops to constants
            as well.
            (ao_ref_init_from_vn_reference): Use 'off' member for
            ARRAY_REF and ARRAY_RANGE_REF instead of recomputing it.
            (valueize_refs_1): Also fixup 'off' of ARRAY_RANGE_REF.

            * gcc.dg/torture/pr113831.c: New testcase.
            * gcc.dg/tree-ssa/ssa-fre-104.c: Likewise.