From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
	id B42753858D38; Wed, 11 Jan 2023 14:42:27 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org B42753858D38
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1673448147;
	bh=TJvit3PD1mFwbn0AuL1vyPkDo2Snv1rOMGRTBXkfZo4=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=tXf4Gf8y8yffO+5W5uxJgN2gW59S75e6gm9ki4UYzFv21az/gVss2nCRv2GJwh5Mg
	 T6EeAhlduhrMH92NM8I+q7fsF3OdgF6O9xy8OiPfV0QtL3bewq62d+omfs58tLKzS+
	 msnhE16Jbk7D12KbaXohYVB2xmyB7mSD5heVsn4U=
From: "dhowells at redhat dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/108370] gcc doesn't merge bitwise-AND if an explicit
 comparison against 0 is given
Date: Wed, 11 Jan 2023 14:42:27 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: c
X-Bugzilla-Version: 12.2.1
X-Bugzilla-Keywords: missed-optimization
X-Bugzilla-Severity: normal
X-Bugzilla-Who: dhowells at redhat dot com
X-Bugzilla-Status: NEW
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-108370-4-myjfmtW9Vb@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-108370-4@http.gcc.gnu.org/bugzilla/>
References: <bug-108370-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108370

--- Comment #3 from dhowells at redhat dot com <dhowells at redhat dot com>=
 ---
We don't want to do:

   return ((unsigned int) bio->bi_flags >> bit & 1) !=3D 0;

if we can avoid it as "bit" is usually constant - though I'm guessing the
optimiser should handle that?=