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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/107839] spurious "may be used uninitialized"
 warning while all uses are under "if (c)"
Date: Mon, 05 Dec 2022 09:32:45 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107839

--- Comment #4 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:44c8402d35160515b3c09fd2bc239587e0c32a2b

commit r13-4491-g44c8402d35160515b3c09fd2bc239587e0c32a2b
Author: Richard Biener <rguenther@suse.de>
Date:   Fri Dec 2 14:52:20 2022 +0100

    tree-optimization/107833 - invariant motion of uninit uses

    The following fixes a wrong-code bug caused by loop invariant motion
    hoisting an expression using an uninitialized value outside of its
    controlling condition causing IVOPTs to use that to rewrite a defined
    value.  PR107839 is a similar case involving a bogus uninit diagnostic.

            PR tree-optimization/107833
            PR tree-optimization/107839
            * cfghooks.cc: Include tree.h.
            * tree-ssa-loop-im.cc (movement_possibility): Wrap and
            make stmts using any ssa_name_maybe_undef_p operand
            to preserve execution.
            (loop_invariant_motion_in_fun): Call mark_ssa_maybe_undefs
            to init maybe-undefined status.
            * tree-ssa-loop-ivopts.cc (ssa_name_maybe_undef_p,
            ssa_name_set_maybe_undef, ssa_name_any_use_dominates_bb_p,
            mark_ssa_maybe_undefs): Move ...
            * tree-ssa.cc: ... here.
            * tree-ssa.h (ssa_name_any_use_dominates_bb_p,
            mark_ssa_maybe_undefs): Declare.
            (ssa_name_maybe_undef_p, ssa_name_set_maybe_undef): Define.

            * gcc.dg/torture/pr107833.c: New testcase.
            * gcc.dg/uninit-pr107839.c: Likewise.=