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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/25290] PHI-OPT could be rewritten so that is
 uses match
Date: Tue, 08 Jun 2021 23:09:32 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D25290

--- Comment #22 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Without load/store handling, here are the following optimizations that eith=
er
can move to match.pd already or need some extra work to do it:

* value_replacement: need to handle !single_non_singleton_phi_for_edges case
and more than one feeder statement (2 max according to the current definiti=
on)
* cond_removal_in_popcount_clz_ctz_pattern: need 2 feeder statements and
builtin call handling for feeder statements


* two_value_replacement: recored as PR 100958, it can move already
* abs_replacement: needs PROP_gimple_lswitch so we don't change if statemen=
ts
early enough
** I think majority of the abs handling is already in match.pd.
* minmax_replacement: has some handling of comparisions which might not be =
in
the match.pd patterns already.  needs PROP_gimple_lswitch also.
** The handling of:
         if (a <=3D u)
           b =3D MAX (a, d);
         x =3D PHI <b, u>
   needs to moved too.


For the ones which cannot move
* factor_out_conditional_conversion: will never move, though it needs
improvement and moved already (PR 56223 and PR 13563)
* spaceship_replacement: cannot move to match.pd depends on use afterwards
which is not hard to deal with in a match pattern.=