[Bug tree-optimization/117217] [13/14 Regression] ICE in verify_sra_access_forest when copying struct with a union of structs with bool bitfields

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117217

--- Comment #10 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-13 branch has been updated by Martin Jambor
<jamborm@gcc.gnu.org>:

https://gcc.gnu.org/g:b9b0c6e00161e8689936f987aa6c2cadd3715271

commit r13-10113-gb9b0c6e00161e8689936f987aa6c2cadd3715271
Author: Martin Jambor <mjambor@suse.cz>
Date:   Mon Feb 9 10:31:10 2026 +0100

    tree-sra: Do not propagate bit-field accesses across assignments (PR
117217)

    On master at least, this is a bug which no longer reproduces with the
    provided test-cases because after r15-5747-gfd62fdc5e1b3c4:(Jakub
    Jelinek: c++: Small initial fixes for zeroing of padding bits
    [PR117256]), the input to SRA looks very different and SRA does not do
    anything.

    However, before that commit, SRA sees the following input and if it
    encountered something similar now, it could still misbehave in the
    same way:

      D.2908.i = 0;
      D.2908.b = 0;
      e ={v} {CLOBBER(bob)};
      e.b = MEM[(const struct B &)&D.2908];
      D.2908 ={v} {CLOBBER(eos)};

    (Where the "e" in "e.b" is actually a MEM_REF of the union type into
    &e so that is why the "data" field is missing.)

    Field D.2908.b is a SRA candidate of boolean type and has size 1 bit
    because its decl has size 1 bit even though its type has size 8 bits.

    The SRA access representing the store to D.2908.b is then propagated
    across the assignment to e and in the process
    build_user_friendly_ref_for_offset tries to find a nice expression for
    it to possibly use in warnings.  It finds types_compatible_p
    e.data.a.b which however has size 8 bits and so the verifier screams
    when it discovers the discrepancy from the copied-over size of 1 bit.

    This patch avoids the situation by refusing to propagate
    non-byte-sized accesses across assignments.

    gcc/ChangeLog:

    2026-02-06  Martin Jambor  <mjambor@suse.cz>

            PR tree-optimization/117217
            * tree-sra.cc (propagate_subaccesses_from_rhs): Do not propagate
            bit-field children.
            (propagate_subaccesses_from_lhs): Likewise.

    gcc/testsuite/ChangeLog:

    2026-02-06  Martin Jambor  <mjambor@suse.cz>

            PR tree-optimization/117217
            * g++.dg/torture/pr117217-1.C: New test.
            * g++.dg/torture/pr117217-2.C: Likewise.

    (cherry picked from commit 538da7baf6aee075ad13e0b654bd9cc6c9db193a)