From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [63.128.21.124]) by sourceware.org (Postfix) with ESMTP id 5AB093850405 for ; Tue, 10 Nov 2020 20:14:26 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 5AB093850405 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-52-3JRfAKFpMlqu748H-dOEOA-1; Tue, 10 Nov 2020 15:14:22 -0500 X-MC-Unique: 3JRfAKFpMlqu748H-dOEOA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 97A93100747A; Tue, 10 Nov 2020 20:14:21 +0000 (UTC) Received: from tucnak.zalov.cz (ovpn-113-127.ams2.redhat.com [10.36.113.127]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 319FD5B4A2; Tue, 10 Nov 2020 20:14:20 +0000 (UTC) Received: from tucnak.zalov.cz (localhost [127.0.0.1]) by tucnak.zalov.cz (8.16.1/8.16.1) with ESMTPS id 0AAKEHIN2578196 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Tue, 10 Nov 2020 21:14:17 +0100 Received: (from jakub@localhost) by tucnak.zalov.cz (8.16.1/8.16.1/Submit) id 0AAKEFsT2578195; Tue, 10 Nov 2020 21:14:15 +0100 Date: Tue, 10 Nov 2020 21:14:15 +0100 From: Jakub Jelinek To: Stefan Kanthak Cc: Eric Botcazou , gcc-patches@gcc.gnu.org Subject: Re: [PATCH] Better __ashlDI3, __ashrDI3 and __lshrDI3 functions, plus fixed __bswapsi2 function Message-ID: <20201110201415.GX3788@tucnak> Reply-To: Jakub Jelinek References: <116F1589A8244FB494091BCD4E6398AB@H270> <7786108.h9Zq5u0u6d@fomalhaut> <003190C0741B4AF0B73E189026EADC84@H270> MIME-Version: 1.0 In-Reply-To: <003190C0741B4AF0B73E189026EADC84@H270> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Spam-Status: No, score=-6.1 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H5, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 10 Nov 2020 20:14:27 -0000 On Tue, Nov 10, 2020 at 08:44:32PM +0100, Stefan Kanthak wrote: > Eric Botcazou wrote: > > >> The implementation of the __ashlDI3(), __ashrDI3() and __lshrDI3() functions > >> is rather bad, it yields bad machine code at least on i386 and AMD64. Since > >> GCC knows how to shift integers twice the register size these functions can > >> be written as one-liners. > > > > These functions are precisely meant to be used when GCC cannot do that. > > On which processor(s) is GCC unable to generate code for DWtype shifts? E.g. avr-none, msp430-elf, pdp11-aout. And I see recursive __cmpdi2 calls on avr-none too. Jakub