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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/66502] SCCVN can't handle PHIs optimistically
 optimally
Date: Mon, 03 Jan 2022 09:50:35 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D66502

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
      Known to work|                            |10.3.1
             Status|ASSIGNED                    |RESOLVED

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #5)
> (In reply to Richard Biener from comment #4)
> > SCCVN preference changed.  Missed optimization remains (now the other
> > variant).
>=20
> GCC 10 looks like it can handle both now. I don't know if that means this
> can be marked as fixed though.

So it looks like we now first value-number j to a (backedge not executable)
and in the second iteration (backedge executable) we value-number it to i.
I guess the special-casing of a single executable edge makes this work now
and also ensure we don't oscillate between both choices.=