From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 6C6D13857012; Thu, 26 Oct 2023 15:37:38 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 6C6D13857012 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1698334658; bh=RUWwyLLxTWDg/tnquc2A+HuvwZVoowPq1VPlTtxAF2o=; h=From:To:Subject:Date:In-Reply-To:References:From; b=En5UEooRwTWP1thFPZSis6Xqxus1uvqI46JnjO1W3mW4lJ7buqWVOxKJNu4Mg+zdx f6Zb/QUdiWRTGq9xURDsOt4M2DVUV6YgknF5PCxOVZJuhWkOFRActLbNPI1L1+oPSY l3fHODSaq72OtUK1MAJYR01uCqt7sg4AUj5OYi4A= From: "vvvvvv at google dot com" To: elfutils-devel@sourceware.org Subject: [Bug libdw/30967] Discriminator in Dwarf_Line_s may exceed 24 bits Date: Thu, 26 Oct 2023 15:37:38 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: elfutils X-Bugzilla-Component: libdw X-Bugzilla-Version: unspecified X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: vvvvvv at google dot com X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Resolution: X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: unassigned at sourceware dot 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://sourceware.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 List-Id: https://sourceware.org/bugzilla/show_bug.cgi?id=3D30967 --- Comment #9 from Aleksei Vetrov --- (In reply to Frank Ch. Eigler from comment #7) > So my preferred workaround: I like this workaround and it works in our use case. > appears to be based on the assumption that truncated bitfields will not > collide. Has this assumption been tested? No such assumption can be made, there is no guarantees from DWARF standard = and it is possible to manually generate DWARF with discriminators exceeding even "unsigned int": just use any library and shift all values by 32 bits. It wi= ll be well within standard, however compilers are not expected to behave like thi= s. In an "liblog.so" attachment truncated values don't collide. I'm more interested in this: what is worst that can happen on discriminator collision? We are not using discriminator at all in ABI monitoring, so I'm = not familiar with its use cases. --=20 You are receiving this mail because: You are on the CC list for the bug.=