[Bug tree-optimization/97164] [8/9/10/11 Regression] incorrect offset on structure member where type of that member has aligned attribute

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97164

--- Comment #10 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:50bc94898fac1bd9cc1dabf227208fb5d369c4c4

commit r11-4282-g50bc94898fac1bd9cc1dabf227208fb5d369c4c4
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Oct 23 10:05:17 2020 +0200

    stor-layout: Reject forming arrays with elt sizes not divisible by elt
alignment [PR97164]

    As mentioned in the PR, since 2005 we reject if array elements are smaller
    than their alignment (i.e. overaligned elements), because such arrays don't
    make much sense, only their first element is guaranteed to be aligned as
    user requested, but the next element can't be.
    The following testcases show something we've been silent about but is
    equally bad, the 2005 case is just the most common special case of that
    the array element size is not divisible by the alignment.  In those arrays
    too only the first element is guaranteed to be properly aligned and the
    second one can't be.

    This patch rejects those cases too, but keeps the existing wording for the
    old common case.

    Unfortunately, the patch breaks bootstrap, because libbid uses this mess
    (forms arrays with 24 byte long elements with 16 byte element alignment).
    I don't really see justification for that, so I've decreased the alignment
    to 8 bytes instead.

    2020-10-23  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/97164
    gcc/
            * stor-layout.c (layout_type): Also reject arrays where element
size
            is constant, but not a multiple of element alignment.
    gcc/testsuite/
            * c-c++-common/pr97164.c: New test.
            * gcc.c-torture/execute/pr36093.c: Move ...
            * gcc.dg/pr36093.c: ... here.  Add dg-do compile and dg-error
            directives.
            * gcc.c-torture/execute/pr43783.c: Move ...
            * gcc.dg/pr43783.c: ... here.  Add dg-do compile, dg-options and
            dg-error directives.
    libgcc/config/libbid/
            * bid_functions.h (UINT192): Decrease alignment to 8 bytes.