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From: "tschwinge at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/90591] Avoid unnecessary data transfer out of
 OMP construct
Date: Mon, 22 Mar 2021 11:37:37 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D90591

Thomas Schwinge <tschwinge at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|sandra at gcc dot gnu.org          |tschwinge at gcc do=
t gnu.org

--- Comment #6 from Thomas Schwinge <tschwinge at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #3)
> I think while relying on a robust IPA analysis and optimization framework
> sounds appealing the problem is _much_ easier solved before OMP/OACC
> lowering and I would strongly suggest to tackle the problem from that side
> if you want a
> workable solution in a timely manner.

ACK.  WIP:
<http://mid.mail-archive.com/87eege1y2g.fsf@dem-tschwing-1.ger.mentorg.com>.

> I realize that has a plethora of its own issues, first of all it seems
> the respective lowering is done _very_ early - aka the optimization would
> need to be part of omplower? (I see .omp_data_i constructed there)
>=20
> So what you need is liveness and def/use analysis on high GIMPLE which I
> think is straight-forward enough.  You have no SSA form at your hands
> (actually SSA names can appear and there'll be use->def links but
> no immediate uses).=