From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 35425 invoked by alias); 16 Dec 2015 13:51:52 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 35405 invoked by uid 89); 16 Dec 2015 13:51:51 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.6 required=5.0 tests=AWL,BAYES_00,KAM_LAZY_DOMAIN_SECURITY,T_RP_MATCHES_RCVD autolearn=no version=3.3.2 X-HELO: e06smtp06.uk.ibm.com Received: from e06smtp06.uk.ibm.com (HELO e06smtp06.uk.ibm.com) (195.75.94.102) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (CAMELLIA256-SHA encrypted) ESMTPS; Wed, 16 Dec 2015 13:51:49 +0000 Received: from localhost by e06smtp06.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 16 Dec 2015 13:51:45 -0000 Received: from d06dlp03.portsmouth.uk.ibm.com (9.149.20.15) by e06smtp06.uk.ibm.com (192.168.101.136) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; Wed, 16 Dec 2015 13:51:43 -0000 X-IBM-Helo: d06dlp03.portsmouth.uk.ibm.com X-IBM-MailFrom: vogt@linux.vnet.ibm.com X-IBM-RcptTo: gcc-patches@gcc.gnu.org Received: from b06cxnps4076.portsmouth.uk.ibm.com (d06relay13.portsmouth.uk.ibm.com [9.149.109.198]) by d06dlp03.portsmouth.uk.ibm.com (Postfix) with ESMTP id 7C80B1B08069 for ; Wed, 16 Dec 2015 13:52:15 +0000 (GMT) Received: from d06av06.portsmouth.uk.ibm.com (d06av06.portsmouth.uk.ibm.com [9.149.37.217]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id tBGDphaU34734168 for ; Wed, 16 Dec 2015 13:51:43 GMT Received: from d06av06.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av06.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id tBGDpgCn024967 for ; Wed, 16 Dec 2015 06:51:43 -0700 Received: from bl3ahm9f.de.ibm.com (dyn-9-152-212-91.boeblingen.de.ibm.com [9.152.212.91]) by d06av06.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id tBGDpg56024964; Wed, 16 Dec 2015 06:51:42 -0700 Received: from dvogt by bl3ahm9f.de.ibm.com with local (Exim 4.76) (envelope-from ) id 1a9CUX-0005YR-V9; Wed, 16 Dec 2015 14:51:42 +0100 Date: Wed, 16 Dec 2015 13:51:00 -0000 From: Dominik Vogt To: gcc-patches@gcc.gnu.org Cc: Andreas Krebbel , Ulrich Weigand Subject: Re: [PATCH] S/390: Allow to use r1 to r4 as literal pool base. Message-ID: <20151216135141.GA19006@linux.vnet.ibm.com> Reply-To: vogt@linux.vnet.ibm.com Mail-Followup-To: gcc-patches@gcc.gnu.org, Andreas Krebbel , Ulrich Weigand References: <20151216064952.GA3191@linux.vnet.ibm.com> <20151216125145.C22A51513@oc7340732750.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151216125145.C22A51513@oc7340732750.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15121613-0025-0000-0000-000005467B3F X-SW-Source: 2015-12/txt/msg01608.txt.bz2 On Wed, Dec 16, 2015 at 01:51:45PM +0100, Ulrich Weigand wrote: > Dominik Vogt wrote: > > > r2 through r4 should be fine. [ Not sure if there will be many (any?) cases > > > where one of those is unused but r5 isn't, however. ] > > > > This can happen if the function only uses register pairs > > (__int128). Actually I'm not sure whether r2 and r4 are valid > > candidates. > > Huh? Why not? Because I'm not sure it is possible to write code where r2 (r4) is free but r3 (r5) is not - at least when s390_emit_prologue is called. Writing code that uses r4 and r5 but not r3 was diffucult enough: __int128 gi; const int c = 0x12345678u; int foo(void) { gi += c; return c; } Ciao Dominik ^_^ ^_^ -- Dominik Vogt IBM Germany