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 0D1CC385840D for ; Tue, 19 Oct 2021 07:46:04 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 0D1CC385840D 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-564-c1iPkh5ONmuWQSr8RwRlfA-1; Tue, 19 Oct 2021 03:46:02 -0400 X-MC-Unique: c1iPkh5ONmuWQSr8RwRlfA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7494F10A8E01; Tue, 19 Oct 2021 07:46:01 +0000 (UTC) Received: from tucnak.zalov.cz (unknown [10.39.193.172]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 0E9C960BF1; Tue, 19 Oct 2021 07:46:00 +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 19J7jwrH2906486 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Tue, 19 Oct 2021 09:45:58 +0200 Received: (from jakub@localhost) by tucnak.zalov.cz (8.16.1/8.16.1/Submit) id 19J7jvpT2906485; Tue, 19 Oct 2021 09:45:57 +0200 Date: Tue, 19 Oct 2021 09:45:57 +0200 From: Jakub Jelinek To: Siddhesh Poyarekar Cc: gcc-patches@gcc.gnu.org Subject: Re: [PATCH v2] tree-object-size: Make unknown a computation Message-ID: <20211019074557.GK304296@tucnak> Reply-To: Jakub Jelinek References: <20211019065813.GJ304296@tucnak> <20211019073830.303140-1-siddhesh@gotplt.org> MIME-Version: 1.0 In-Reply-To: <20211019073830.303140-1-siddhesh@gotplt.org> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 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=-5.4 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: 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, 19 Oct 2021 07:46:05 -0000 On Tue, Oct 19, 2021 at 01:08:30PM +0530, Siddhesh Poyarekar wrote: > Compute the unknown size value as a function of the min/max bit of > object_size_type. This transforms into a neat little branchless > sequence on x86_64: > > movl %edi, %eax > sarl %eax > xorl $1, %eax > negl %eax > cltq > > which should be faster than loading the value from memory. A quick > unscientific test using > > `time make check-gcc RUNTESTFLAGS="dg.exp=builtin*"` > > shaves about half a second off execution time with this. Also simplify > implementation of unknown_object_size. > > gcc/ChangeLog: > > * tree-object-size.c (unknown): Make into a function. Adjust > all uses. > (unknown_object_size): Simplify implementation. > > Signed-off-by: Siddhesh Poyarekar Ok for trunk if it passes bootstrap/regtest. Jakub