[Bug bootstrap/102681] [12 Regression] AArch64 bootstrap failure

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102681

--- Comment #22 from CVS 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:fe8475c500939011b90504304aec61bf6f48ac7d

commit r12-4625-gfe8475c500939011b90504304aec61bf6f48ac7d
Author: Richard Biener <rguenther@suse.de>
Date:   Fri Oct 22 10:32:36 2021 +0200

    bootstrap/102681 - properly CSE PHIs with default def args

    The PR shows that we fail to CSE PHIs containing (different)
    default definitions due to the fact on how we now handle
    on-demand build of VN_INFO.  The following fixes this in the
    same way the PHI visitation code does.

    On gcc.dg/ubsan/pr81981.c this causes one expected warning to be
    elided since the uninit pass sees the change

       <bb 4> [local count: 1073741824]:
       # u$0_2 = PHI <u$0_5(D)(3), i_3(D)(5)>
    -  # cstore_11 = PHI <t$0_6(D)(3), i_3(D)(5)>
       v = u$0_2;
    -  return cstore_11;
    +  return u$0_2;

    and thus only one of the conditionally uninitialized uses (the
    other became dead).  I have XFAILed the missing diagnostic,
    I don't see a way to preserve that.

    2021-10-22  Richard Biener  <rguenther@suse.de>

            PR bootstrap/102681
            * tree-ssa-sccvn.c (vn_phi_insert): For undefined SSA args
            record VN_TOP.
            (vn_phi_lookup): Likewise.

            * gcc.dg/tree-ssa/ssa-fre-97.c: New testcase.
            * gcc.dg/ubsan/pr81981.c: XFAIL one case.