From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 64B7D3840C16; Mon, 8 Feb 2021 21:40:20 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 64B7D3840C16 From: "mark at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/98692] Unitialized Values reported only with -Os Date: Mon, 08 Feb 2021 21:40:20 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: rtl-optimization X-Bugzilla-Version: 10.2.1 X-Bugzilla-Keywords: diagnostic X-Bugzilla-Severity: normal X-Bugzilla-Who: mark 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: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: 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 X-BeenThere: gcc-bugs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-bugs mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 08 Feb 2021 21:40:20 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D98692 --- Comment #10 from Mark Wielaard --- (In reply to Will Schmidt from comment #9) > (In reply to Segher Boessenkool from comment #5) > > Have you tried a new valgrind? > >=20 > > Either this is (or was) a known problem in valgrind, or it is related to > > one. Cc:ing Aaron, he might know more (he wrote the GCC optimisations > > that expose the problem). >=20 >=20 > I've recreated against new (built out of upstream git) valgrind: > with --track-origins=3Dyes >=20 >=20 > =3D=3D37507=3D=3D=20 > argv[0]=3D./a.out > =3D=3D37507=3D=3D Use of uninitialised value of size 8 > =3D=3D37507=3D=3D at 0x10000618: main (pr9862.C:16) > =3D=3D37507=3D=3D Uninitialised value was created by a stack allocation > =3D=3D37507=3D=3D at 0x100007D4: isVariable(char*) (pr9862.C:5) Trying to get hold of a ppc64 setup. But could you try with --vgdb-error=3D= 0 and then (in another window) gdb ./a.out and target remote | vgdb and continue = till you get the TRAP. Then disassamble so we can see the exact instruction that generates the use of uninitialised value?=