[Bug testsuite/102501] [12 regression] several test case failures after r12-3876

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102501

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Aldy Hernandez <aldyh@gcc.gnu.org>:

https://gcc.gnu.org/g:24e30f485bc80c823393d8fc62b65f860230e04b

commit r12-3970-g24e30f485bc80c823393d8fc62b65f860230e04b
Author: Aldy Hernandez <aldyh@redhat.com>
Date:   Tue Sep 28 17:53:57 2021 +0200

    [PR102501] Adjust jump threading testcases for ppc64* and others.

    I really don't know what to do here.  This is a bit of whack-o-mole.
    The IL is sufficiently different for various architectures that any
    tweak can cause the number of jump threads to vary.

    For the pr7745-2.c testcase, we have less threading candidates because 2
    of them now cross loop boundaries.  Interestingly, this test matches
    "Jumps threaded", not threads registered, so the block copier can
    drop threads at copying time adding further confusion.

    For example, we can register N threads, but the old copier can cancel
    N-M threads while updating the CFG for a variety of different reasons
    (removed edges, threading through loop exits, etc).  This makes the
    "Registering jump threads" not to match the total number of threads this
    test checks for with "Jumps threaded".

    The pr66752-3.c test OTOH, is just a matter of thread4 eliminating the
    "if".  I had erroneously thought it would always be eliminated by
    thread3, but we really don't care where it gets cleaned up.  All we know
    is that DCE can't depend on the early threaders doing this work, because
    it may cross loop boundaries.  I've chosen thread4 arbitrarily, but we
    could just as easily pick the ".optimized" dump.

    Sorry, I'm really at my wits end here.  I don't see any clean path
    forward, except rewrite these tests as gimple IL.  They're close to useless
    as they sit.

    gcc/testsuite/ChangeLog:

            PR testsuite/102501
            * gcc.dg/tree-ssa/pr66752-3.c: Adjust.
            * gcc.dg/tree-ssa/pr77445-2.c: Adjust.