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 F1CFA388A029 for ; Mon, 4 Jan 2021 15:28:05 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org F1CFA388A029 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-476-PdP8VZW1PIy7w4RF2i6xXQ-1; Mon, 04 Jan 2021 10:28:02 -0500 X-MC-Unique: PdP8VZW1PIy7w4RF2i6xXQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 150A6AFA80; Mon, 4 Jan 2021 15:28:01 +0000 (UTC) Received: from localhost.localdomain (ovpn-112-189.phx2.redhat.com [10.3.112.189]) by smtp.corp.redhat.com (Postfix) with ESMTP id D5C77271B0; Mon, 4 Jan 2021 15:28:00 +0000 (UTC) Subject: Re: [20/23] rtlanal: Add simple_regno_set To: gcc-patches@gcc.gnu.org, richard.sandiford@arm.com References: From: Jeff Law Message-ID: <1e6dcf37-8c3b-8420-f862-637785b9fe44@redhat.com> Date: Mon, 4 Jan 2021 08:28:00 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-US X-Spam-Status: No, score=-5.8 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, NICE_REPLY_A, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H4, 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: Mon, 04 Jan 2021 15:28:07 -0000 On 12/16/20 5:47 PM, Richard Sandiford wrote: > Jeff Law writes: >> On 11/13/20 1:21 AM, Richard Sandiford via Gcc-patches wrote: >>> This patch adds a routine for finding a “simple” SET for a register >>> definition. See the comment in the patch for details. >>> >>> gcc/ >>> * rtl.h (simple_regno_set): Declare. >>> * rtlanal.c (simple_regno_set): New function. >> So I was a bit confused that this is supposed to reject read-write, but >> what it's really rejecting is a narrow subset of read-write.  In >> particular it rejects things that are potentially RMW via subregs. It >> doesn't prevent the destination from appearing as a source operand.  You >> might consider clarifying the comment. > Yeah, in hindsight it was a mistake to spell out the RMW point > separately when it was really just an extra condition on the subreg. > > I'd tweaked this comment and the mux-utils.h one (in response > to Martin's feedback) while doing the cross-target testing, > but forgot to include the changes to the committed version. > (The tested versions were otherwise identical, honest.) > > Tested on aarch64-linux-gnu and x86_64-linux-gnu. OK to install? > > Thanks, > Richard > > > gcc/ > * mux-utils.h (pointer_mux::m_ptr): Tweak description of contents. > * rtlanal.c (simple_regno_set): Tweak description to clarify the > RMW condition. OK jeff