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From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/106922] [12/13 Regression] Bogus
 uninitialized warning on boost::optional<<std::vector<std::string>>>, missed
 FRE
Date: Thu, 15 Sep 2022 12:36:07 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106922

--- Comment #8 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:5edf02ed2b6de024f83a023d046a6a18f645bc83

commit r13-2683-g5edf02ed2b6de024f83a023d046a6a18f645bc83
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Sep 15 13:33:23 2022 +0200

    tree-optimization/106922 - PRE and virtual operand translation

    PRE implicitely keeps virtual operands at the blocks incoming version
    but the explicit updating point during PHI translation fails to trigger
    when there are no PHIs at all in a block.  Later lazy updating then
    fails because of a too lose block check.  A similar issues plagues
    reference invalidation when checking the ANTIC_OUT to ANTIC_IN
    translation.  The following fixes both and makes the lazy updating
    work.

    The diagnostic testcase unfortunately requires boost so the
    testcase is the one I reduced for a missed optimization in PRE.
    The testcase fails with -m32 on x86_64 because we optimize too
    much before PRE which causes PRE to not trigger so we fail to
    eliminate a full redundancy.  I'm going to open a separate bug
    for this.  Hopefully the !lp64 selector is good enough.

            PR tree-optimization/106922
            * tree-ssa-pre.cc (translate_vuse_through_block): Only
            keep the VUSE if its def dominates PHIBLOCK.
            (prune_clobbered_mems): Rewrite logic so we check whether
            a value dies in a block when the VUSE def doesn't dominate it.

            * g++.dg/tree-ssa/pr106922.C: New testcase.=