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 63908398641F; Tue, 30 Aug 2022 15:19:53 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 63908398641F
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1661872793;
	bh=MKe4dQjKbLV5+nmqWKtiTfewBIDGyjyVfbt6lFTCZxs=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=RlEphFkoXJjXb0dAo5SHUpS8jFS0BmNPIzzlDOdp3LcQY69FEeCxR2egKZGXswAYr
	 ulR2c3Yc7qD5RQJQiVfoWxhXpt3zVktlYVd1bDE9OzTjvo5MPVOsK8l9AprbysIAtm
	 zjmxmbYan4hUsPVRe2zoycD+zJrrdZgk8X3chqno=
From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug testsuite/31290] gcc.c-torture/execute/920612-1.c and
 gcc.c-torture/execute/920711-1.c depend on signed overflow being defined
Date: Tue, 30 Aug 2022 15:19:53 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: testsuite
X-Bugzilla-Version: 4.3.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: pinskia at gcc dot gnu.org
X-Bugzilla-Status: RESOLVED
X-Bugzilla-Resolution: FIXED
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 4.7.0
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-31290-4-JFYmuDTmON@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-31290-4@http.gcc.gnu.org/bugzilla/>
References: <bug-31290-4@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=3D31290

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Philipp from comment #4)
> I disagree about this bug for gcc.c-torture/execute/920711-1.c. I think
> there was no bug here, and the "fix" actually introduced a problem, and
> should be reverted:

No there is a bug.
int f(long a){return (--a > 0);}
int main(){if(f(0x80000000L)=3D=3D0)abort();exit(0);}


0x80000000L is still 0x80000000 bitwise. so we get 0x80000000L - 1 which is
undefined if long is 32bits. If long is 64bits then 0x80000000L is still th=
at
(and no implementation defined casting) and not undefined there.

> By section 4.5 of the GCC manual https://gcc.gnu.org/onlinedocs/gcc/Integ=
ers-implementation.html#Integers-implementation the result of the conversio=
n is -1.

No it is INT_MIN (for 32bit long):
For conversion to a type of width N, the value is reduced modulo 2^N to be
within range of the type; no signal is raised.

That means 0x80000000ULL will be 0x80000000L (if long is 32bits and long lo=
ng
is 64bit).=