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Subject: [Bug tree-optimization/109539] [13/14 Regression] Compile-time hog
 in gimple-ssa-warn-access.cc since r13-6706-gadb70c2d1060b3
Date: Tue, 18 Apr 2023 12:38:46 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109539

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-13 branch has been updated by Richard Biener
<rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:68aea7801848f978f8b5461807dfd3b7a504da1e

commit r13-7215-g68aea7801848f978f8b5461807dfd3b7a504da1e
Author: Richard Biener <rguenther@suse.de>
Date:   Tue Apr 18 11:49:48 2023 +0200

    tree-optimization/109539 - restrict PHI handling in access diagnostics

    Access diagnostics visits the SSA def-use chains to diagnose things like
    dangling pointer uses.  When that runs into PHIs it tries to prove
    all incoming pointers of which one is the currently visited use are
    related to decide whether to keep looking for the PHI def uses.
    That turns out to be overly optimistic and thus costly.  The following
    scraps the existing handling for simply requiring that we eventually
    visit all incoming pointers of the PHI during the def-use chain
    analysis and only then process uses of the PHI def.

    Note this handles backedges of natural loops optimistically, diagnosing
    the first iteration.  There's gcc.dg/Wuse-after-free-2.c containing
    a testcase requiring this.

            PR tree-optimization/109539
            * gimple-ssa-warn-access.cc (pass_waccess::check_pointer_uses):
            Re-implement pointer relatedness for PHIs.

    (cherry picked from commit fdbaab2dc886f78a1e75512eeee0faa17e77c862)=