From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 129194 invoked by alias); 7 Jan 2018 10:31:21 -0000 Mailing-List: contact gnu-gabi-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Post: List-Help: List-Subscribe: Sender: gnu-gabi-owner@sourceware.org Received: (qmail 129166 invoked by uid 89); 7 Jan 2018 10:31:20 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Checked: by ClamAV 0.99.2 on sourceware.org X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.0 required=5.0 tests=AWL,BAYES_00,KAM_LAZY_DOMAIN_SECURITY,RCVD_IN_DNSWL_NONE,T_RP_MATCHES_RCVD autolearn=no version=3.3.2 spammy=H*Ad:U*amodra X-Spam-Status: No, score=-1.0 required=5.0 tests=AWL,BAYES_00,KAM_LAZY_DOMAIN_SECURITY,RCVD_IN_DNSWL_NONE,T_RP_MATCHES_RCVD autolearn=no version=3.3.2 X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on sourceware.org X-Spam-Level: X-Spam-User: qpsmtpd, 2 recipients X-HELO: albireo.enyo.de Received: from albireo.enyo.de (HELO albireo.enyo.de) (5.158.152.32) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Sun, 07 Jan 2018 10:31:19 +0000 Received: from [172.17.203.2] (helo=deneb.enyo.de) by albireo.enyo.de with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) id 1eY8EQ-00071I-UX; Sun, 07 Jan 2018 10:31:10 +0000 Received: from fw by deneb.enyo.de with local (Exim 4.89) (envelope-from ) id 1eY8EQ-0007iq-NU; Sun, 07 Jan 2018 11:31:10 +0100 From: Florian Weimer To: Roland McGrath Cc: Rahul Chaudhry , Cary Coutant , Sriraman Tallam , Rahul Chaudhry via gnu-gabi , Suprateeka R Hegde , David Edelsohn , Rafael Avila de Espindola , Binutils Development , Alan Modra , Xinliang David Li , Sterling Augustine , Paul Pluzhnikov , Ian Lance Taylor , "H.J. Lu" , Luis Lozano , Peter Collingbourne , Rui Ueyama , llvm-dev@lists.llvm.org Subject: Re: Reducing code size of Position Independent Executables (PIE) by shrinking the size of dynamic relocations section References: <8737cosnym.fsf@localhost.localdomain.i-did-not-set--mail-host-address--so-tickle-me> <7e698a5f-32d7-6549-7e23-8850b85e6c10@gmail.com> <874lozec25.fsf@mid.deneb.enyo.de> Date: Mon, 01 Jan 2018 00:00:00 -0000 In-Reply-To: (Roland McGrath's message of "Sun, 07 Jan 2018 07:43:36 +0000") Message-ID: <87y3laarkh.fsf@mid.deneb.enyo.de> MIME-Version: 1.0 Content-Type: text/plain X-IsSubscribed: yes X-SW-Source: 2018-q1/txt/msg00000.txt.bz2 * Roland McGrath: > Given this corpus of "reloc traces" you can code up many competing encoding > formats and do serious measurements of their space savings across the > entire corpus from simple simulations without having to implement each > encoding in an actual toolchain and dynamic linker to do the analysis. On the other hand, the linker currently assumes that the order in which relative relocations are emitted does not matter. With a different encoding scheme, future linkers might reorder the relocations or data objects themselves, either to reduce relocation encoding size, or to make relocations more efficient (perhaps to support vectorization). Unfortunately, the numbers which can be derived from ET_DYN files will not reflect to what extent such reordering is possible.