From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 40C6E3858413; Mon, 3 Oct 2022 23:12:20 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 40C6E3858413 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1664838740; bh=BiRMvFf1VGNa89jlnlZIUUjouA84in1gT8KIFdLfbdM=; h=From:To:Subject:Date:In-Reply-To:References:From; b=UCRloRLrlT8IRdwesCQiflBvA0bhdcEvbkoNUhbKhFzK08AJ+wkOfXPUaOolBpf1R qz0Tu+6xbnRrL2oN3qGSskS5VehitrxVqYxAn5GIK/D+3Dfexn/2fTaNx0vbRgDlkb NheAowuQXuszP+Dv0zA8AKfXq5R9OuDQT9+oO8qY= From: "bergner at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/106757] [12/13 Regression] Incorrect "writing 1 byte into a region of size 0" on a vectorized loop Date: Mon, 03 Oct 2022 23:12:19 +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: 12.2.0 X-Bugzilla-Keywords: diagnostic X-Bugzilla-Severity: normal X-Bugzilla-Who: bergner at gcc dot gnu.org 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: 12.3 X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: cc Message-ID: In-Reply-To: References: 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: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106757 Peter Bergner changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |bergner at gcc dot gnu.org --- Comment #3 from Peter Bergner --- Is this the same bug, so just a simpler test case? bergner@fowler:LTC193379$ cat bug.c int len =3D 16; extern char *src; char dst[16]; void foo (void) { #ifdef OK for (int i =3D 0; i < 16; i++) #else for (int i =3D 0; i < len; i++) #endif dst[i] =3D src[i]; } bergner@fowler:LTC193379$ /home/bergner/gcc/build/gcc-fsf-mainline-ltc193379-debug/gcc/xgcc -B/home/bergner/gcc/build/gcc-fsf-mainline-ltc193379-debug/gcc -S -O3 -DOK -ftree-vectorize bug.c bergner@fowler:LTC193379$ /home/bergner/gcc/build/gcc-fsf-mainline-ltc193379-debug/gcc/xgcc -B/home/bergner/gcc/build/gcc-fsf-mainline-ltc193379-debug/gcc -S -O3 -UOK -fno-tree-vectorize bug.c bergner@fowler:LTC193379$ /home/bergner/gcc/build/gcc-fsf-mainline-ltc193379-debug/gcc/xgcc -B/home/bergner/gcc/build/gcc-fsf-mainline-ltc193379-debug/gcc -S -O3 -UOK -ftree-vectorize bug.c bug.c: In function =E2=80=98foo=E2=80=99: bug.c:13:12: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=3D] 13 | dst[i] =3D src[i]; | ~~~~~~~^~~~~~~~ bug.c:3:6: note: at offset 16 into destination object =E2=80=98dst=E2=80=99= of size 16 3 | char dst[16]; | ^~~ bug.c:13:12: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=3D] 13 | dst[i] =3D src[i]; | ~~~~~~~^~~~~~~~ bug.c:3:6: note: at offset 17 into destination object =E2=80=98dst=E2=80=99= of size 16 3 | char dst[16]; | ^~~ I'll note that -fno-unroll-loops doesn't affect anything.=