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 [170.10.129.124]) by sourceware.org (Postfix) with ESMTPS id ED01E3857C46 for ; Mon, 11 Apr 2022 06:34:37 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org ED01E3857C46 Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-213-sak4gqQaPv6sHs0wKK1ahg-1; Mon, 11 Apr 2022 02:34:34 -0400 X-MC-Unique: sak4gqQaPv6sHs0wKK1ahg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id CCECB8001EA; Mon, 11 Apr 2022 06:34:33 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.193.61]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 17D48111E410; Mon, 11 Apr 2022 06:34:32 +0000 (UTC) From: Florian Weimer To: Adam Sampson via Libc-alpha Subject: Re: [PATCH v1 2/2] x86_64: Add {u}int_fast defs ideal for x86_64 References: <20220411010913.1061799-1-goldstein.w.n@gmail.com> <20220411010913.1061799-2-goldstein.w.n@gmail.com> Date: Mon, 11 Apr 2022 08:34:31 +0200 In-Reply-To: (Adam Sampson via Libc-alpha's message of "Mon, 11 Apr 2022 03:15:25 +0100") Message-ID: <87ee24nn60.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 2.78 on 10.11.54.3 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-4.5 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, KAM_NUMSUBJECT, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP, T_SCC_BODY_TEXT_LINE 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: Mon, 11 Apr 2022 06:34:39 -0000 * Adam Sampson via Libc-alpha: > Noah Goldstein via Libc-alpha writes: > >> {u}int_fast{16|32} should never use 64-bit types. 64-bit instructions >> often use more code size (REX prefix) and a variety of instructions >> are slower on many implementations (div, bswap, etc...). > > Isn't that going to cause ABI breakage in other libraries, though? > For example, the jasper JPEG2000 decoder library uses stdint.h's > uint_fast32_t in its public API, and the HDF5 scientific data library > includes constants for the sizes of various types including *int*fast*. Agreed, it's too late for such changes. Thanks, Florian