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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/106727] Missed fold / canonicalization for checking
 if a number is a power of 2
Date: Mon, 04 Mar 2024 22:58:23 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106727

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #1)
> Confirmed.  Expanding __builtin_popcount (n) <=3D 1 as (n & (n - 1)) =3D=
=3D 0
> might be already done.  The canonicalization could be applied if .POPCOUNT
> is available.

No, it is not already done, expanding `__builtin_popcount (n) =3D=3D 1` is =
done
(and including if n is known not to include 0 which is exapnded as `n & (n =
- 1)
=3D=3D 0`)=