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 9840F3858032; Thu,  9 Mar 2023 09:45:46 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 9840F3858032
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1678355146;
	bh=u2eUQtZbFY1gcO34Lr2L1OuvVLIlbw5VcxstB2mDS8M=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=MIAGSFmRe/XJNCLoHnG6KQFVDtkA7jP68tBM85V6G5M3/0vcStlT8G9mguwXOjej4
	 s9b41COYic3poHmMhBnlSi0irHtqCOVsqN2LhzgIT7wmpP5EfiVcGUwwIYQo8SOzoT
	 dzWvfnQA9xPF/HsDGNZb/IlCjG8cY0A70ud2LdcI=
From: "dcb314 at hotmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/109031] csmith: possible bad code with -O2
 -fno-strict-aliasing since r13-254-gdd3c7873a61019e9
Date: Thu, 09 Mar 2023 09:45:46 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: middle-end
X-Bugzilla-Version: 13.0
X-Bugzilla-Keywords: needs-reduction, wrong-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: dcb314 at hotmail 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-109031-4-jgjSZ0DL0W@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-109031-4@http.gcc.gnu.org/bugzilla/>
References: <bug-109031-4@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=3D109031

--- Comment #24 from David Binderman <dcb314 at hotmail dot com> ---
I tried experimenting with the flags that change -O1 into -O2 and got this:

$ for i in ~/gcc/results.202205*/bin/gcc; do echo $i; $i -w
-ftrivial-auto-var-init=3Dzero -O1 -fno-strict-aliasing bug892.c && (./a.ou=
t 1 |
fgrep g_50); done
/home/dcb36/gcc/results.20220501/bin/gcc
...checksum after hashing g_50 : 646CF84D
/home/dcb36/gcc/results.20220508/bin/gcc
...checksum after hashing g_50 : 646CF84D
/home/dcb36/gcc/results.20220515/bin/gcc
...checksum after hashing g_50 : 646CF84D

$ for i in ~/gcc/results.202205*/bin/gcc; do echo $i; $i -w
-ftrivial-auto-var-init=3Dzero -O1 -fcode-hoisting -fno-strict-aliasing bug=
892.c
&& (./a.out 1 | fgrep g_50); done
/home/dcb36/gcc/results.20220501/bin/gcc
...checksum after hashing g_50 : 646CF84D
/home/dcb36/gcc/results.20220508/bin/gcc
...checksum after hashing g_50 : 646CF84D
/home/dcb36/gcc/results.20220515/bin/gcc
...checksum after hashing g_50 : C21BF3F9

so the -fcode-hoisting looks to be part of the problem.=