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 [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id 0CB363858032 for ; Tue, 19 Oct 2021 15:59:57 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 0CB363858032 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-232-uR7cwAlBOe2IFLa2vgtYcA-1; Tue, 19 Oct 2021 11:59:55 -0400 X-MC-Unique: uR7cwAlBOe2IFLa2vgtYcA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A0BF018D6A25; Tue, 19 Oct 2021 15:59:54 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.194.104]) by smtp.corp.redhat.com (Postfix) with ESMTPS id F05FC641A7; Tue, 19 Oct 2021 15:59:53 +0000 (UTC) From: Florian Weimer To: "Paul A. Clarke" Cc: "Paul A. Clarke via Libc-alpha" Subject: Re: [PATCH] [powerpc] Tighten contraints for asm constant parameters References: <20211019151413.123039-1-pc@us.ibm.com> <871r4h11eb.fsf@oldenburg.str.redhat.com> <20211019155853.GB104437@li-24c3614c-2adc-11b2-a85c-85f334518bdb.ibm.com> Date: Tue, 19 Oct 2021 17:59:52 +0200 In-Reply-To: <20211019155853.GB104437@li-24c3614c-2adc-11b2-a85c-85f334518bdb.ibm.com> (Paul A. Clarke's message of "Tue, 19 Oct 2021 10:58:53 -0500") Message-ID: <87o87lyphj.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-6.4 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 19 Oct 2021 15:59:57 -0000 * Paul A. Clarke: > I was too loose with my characterization of 'i', in contrast to 'n': > > | =E2=80=98n=E2=80=99 > | An immediate integer operand with a known numeric value is allowed= . > | Many systems cannot support assembly-time constants for operands l= ess > | than a word wide. Constraints for these operands should use =E2=80= =98n=E2=80=99 > | rather than =E2=80=98i=E2=80=99. > > The cases changed by the patch require a *known numeric value*, as they a= re > used as immediate values (hardcoded in the generated opcode). > > I will reword to: > There are a few places where only known numeric values are acceptable f= or > `asm` parameters, yet the constraint "i" is used. "i" can include > "symbolic constants whose values will be known only at assembly time or > later." > > Use "n" instead of "i" where known numeric values are required. > > Does that work better? Yes, that explains the difference. Thanks! Florian