[Bug middle-end/108657] [13 Regression] csmith: possible wrong checksum with -O3 and -ftrivial-auto-var-init=zero

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108657

--- Comment #22 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:866555b170016c49beb869a78cbecdeb07c63135

commit r13-6083-g866555b170016c49beb869a78cbecdeb07c63135
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Feb 16 15:35:05 2023 +0100

    tree-ssa-dse: Fix up handling of lhs of internal calls [PR108657]

    The r13-1778 PR106378 tree-ssa-dse change didn't just add special support
    for IFN_LEN_STORE and IFN_MASK_STORE internal function calls as I believe
    was intended, but given that the function was
    if (is builtin) { ... }
    else if (lhs present and non-SSA_NAME) { ... }
    return false;
    and it added a new
    else if (is internal builtin) { ... }
    in between the two, the last if used to be done before on all stmts
    with non-SSA_NAME lhs except for calls to builtin functions, but newly
    isn't done also for calls to internal functions.  In the testcase
    the important internal function is .DEFERRED_INIT, which often has
    non-SSA_NAME lhs, and the change resulted in them no longer being DSEd,
    so a block with nothing in it left but var = .DEFERRED_INIT () and
    var = {CLOBBER} was unrolled several times.

    The following patch does the lhs handling for all stmts with non-SSA_NAME
lhs
    unless initialize_ao_ref_for_dse handled those specially already and
    returned (which is the case for various mem* builtins which don't have
    such lhs, for some cases of calloc which again is fine,and since r13-1778
    also for IFN_LEN_STORE call and some IFN_MASK_STORE calls.
    As IFN_MASK_STORE doesn't have a lhs, the break for the !may_def_ok case
    doesn't seem to change anything, and because we've handled internal fns
    that way in the past, I think it is the right thing to do that again.
    That said, if it is inappropriate for some new ifn, I guess it could
    be added to the switch and just return false; for it instead of break;.

    2023-02-16  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/108657
            * tree-ssa-dse.cc (initialize_ao_ref_for_dse): If lhs of stmt
            exists and is not a SSA_NAME, call ao_ref_init even if the stmt
            is a call to internal or builtin function.

            * gcc.dg/pr108657.c: New test.