From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 129F038930DA; Tue, 6 Apr 2021 11:32:14 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 129F038930DA From: "hubicka at ucw dot cz" To: gcc-bugs@gcc.gnu.org Subject: [Bug lto/99898] Possible LTO object incompatibility on gcc-10 branch Date: Tue, 06 Apr 2021 11:32:13 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: lto X-Bugzilla-Version: 10.2.1 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: hubicka at ucw dot cz 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: Tue, 06 Apr 2021 11:32:14 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99898 --- Comment #10 from Jan Hubicka --- > Many of the *.opt changes are target specific, so you'd need to test it a= lso > across all targets, and furthermore it depends on what exactly is being > saved/restored, many options might be at the same spot. > So perhaps we want to compute some hash of the options stuff (e.g. comput= e it > by the awk scripts that emit options*.[ch]) and use that to determine LTO > compatibility in addition to the version? That would work. One does not really do that in lto header, simply stream the hash before streaming out the optimization_node decl. Bit sad would be that w/o version info you have no indication if you mixed new compiler with old objects or vice versa, but that is minor anoyance I guess. It would be good that compiler would just sorryclaiming that it can not read object files created by different version.. I believe we already safe a diff from default values rather than streaming out all values. An option would be tom strea the option names rather than indexes so adding/removing completely unrelated option does not disturb the file format. Honza >=20 > --=20 > You are receiving this mail because: > You are on the CC list for the bug.=