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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/95185] Failure to optimize specific kind of
 sign comparison check
Date: Mon, 28 Aug 2023 21:08:01 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95185

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |pinskia at gcc dot =
gnu.org
             Status|NEW                         |ASSIGNED

--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #5)
>=20
> Something like:
> Prefer ^ over =3D=3D
> ```
> (for cmp
> (for cmpN
> (for neeq
>  (simplify
>   (neeq:c (cmp @0 @1) @3
>   (if (cmpN =3D=3D inverseof(cmp, TREE_TYPE (type))
>    (bit_xor (cmpN @0 @1) @3)
>   )
>  )
> )))
> ```

Actually we can just do:
```
/* For CMP =3D=3D b, prefer CMP` ^ b. */
(for neeq (ne eq)
 (for cmp (tcc_comparison)
  (simplify
   (neeq:c (cmp@0 @1 @2) @3)
   (bit_xor (bit_not! @0) @3)
  )
 )
)
```
Since we already have folding of (bit_not cmp) in another place.=