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 C2E023858C74; Tue, 31 Oct 2023 14:05:01 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org C2E023858C74
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1698761101;
	bh=kAFE+ucbrr7X7UtNdQBKXAkmnkZvqZuv7bxUbKbPcxQ=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=YNTemE0fWX1PT8MIFOZ649xkHaE4Uj2jCBQc/7J5sd3WMrR8NspO/Mkf/S6QwlI9F
	 3fRNLYkNJincNXjrVj2ZIUmkY9JAG1OkB62G4bdZRu9bz78sofVu3hXQyuN+Ld43iX
	 0xwFZei9rzwYWgu22KVjkitQSUZF1z3N1O3sXokI=
From: "rth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/112296] __builtin_constant_p doesn't
 propagate through member functions
Date: Tue, 31 Oct 2023 14:05:01 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 13.1.0
X-Bugzilla-Keywords: documentation, missed-optimization
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rth at gcc dot gnu.org
X-Bugzilla-Status: ASSIGNED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: rguenth at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-112296-4-iXhOV7Ksdd@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-112296-4@http.gcc.gnu.org/bugzilla/>
References: <bug-112296-4@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=3D112296

--- Comment #9 from Richard Henderson <rth at gcc dot gnu.org> ---
> Thanks.  So yes,
>=20
> macro(x++);
>=20
> incrementing x twice would have been odd - but that's the usual bug
> in this kind of macro definition.  Fixing it by throwing away
> side-effects (and always going the out_of_line_function (x) path!)
> for the __builtin_constant_p argument is an odd choice.

In the beginning __builtin_constant_p was resolved immediately,
so formulating this as

#define macro(x) \
  ({ __typeof(x) _x =3D (x); \
     __builtin_constant_p(_x) })

would always return false, defeating the purpose.

> The execute.exp testcase suggests the intention but the testcases
> verification is somewhat incomplete (it lacks verifying the side-effects
> are gone).

That's probably my omission.  ;-)=