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 3AD2E3858D35 for ; Wed, 28 Jun 2023 12:39:05 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 3AD2E3858D35 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1687955944; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:in-reply-to:in-reply-to: references:references; bh=lYrZcEtY3Aj+rOpFgxt1k7Z25n2DfEeKMvGUd8M5nxs=; b=CbmxQx25nj8zsISLy5LvGO67TMDi/Fo6uWZ+t+OclYYs2DwynbALMSqjbdEYMMWFO/WEzm OaZRL7E0+HfBi2eAY3LYF+Y4vmZjK1O+tHSRTqRNLNnXSQF5U+eIsdZ+cKEPK29i5r6d5C FjPWckZLsFkp3sjSYvQDSuPormRqing= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-248-TTBXX-eNMxKMHdiNJTA40g-1; Wed, 28 Jun 2023 08:39:03 -0400 X-MC-Unique: TTBXX-eNMxKMHdiNJTA40g-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 4752B3C0FCA6; Wed, 28 Jun 2023 12:39:03 +0000 (UTC) Received: from tucnak.zalov.cz (unknown [10.39.195.172]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E9676C09A07; Wed, 28 Jun 2023 12:39:02 +0000 (UTC) Received: from tucnak.zalov.cz (localhost [127.0.0.1]) by tucnak.zalov.cz (8.17.1/8.17.1) with ESMTPS id 35SCd0Wc013297 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Wed, 28 Jun 2023 14:39:00 +0200 Received: (from jakub@localhost) by tucnak.zalov.cz (8.17.1/8.17.1/Submit) id 35SCcx5C013296; Wed, 28 Jun 2023 14:38:59 +0200 Date: Wed, 28 Jun 2023 14:38:54 +0200 From: Jakub Jelinek To: Richard Biener Cc: gcc-patches@gcc.gnu.org Subject: Re: [PATCH] tree-optimization/110434 - avoid ={v} {CLOBBER} from NRV Message-ID: Reply-To: Jakub Jelinek References: <20230628102150.620743857B8E@sourceware.org> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 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=-3.7 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_NONE,TXREP,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Wed, Jun 28, 2023 at 12:32:51PM +0000, Richard Biener wrote: > As said there's nothing run after NRV. There is expansion but in the case I strongly doubt we are trying to stack reuse it for other vars, so maybe it is ok. > > On the other side, could there be partial clobbers for the var -> , > > var.fld = {CLOBBER}; > > ? Or even worse, indirect clobbers (MEM_REF with SSA_NAME pointing to > > var or parts of it)? > > We know that 'var' is not address taken, not sure about the partial > clobbers. We could deal with this in the walk_gimple_op case and > simply remove a clobber when data.modified. LGTM. Jakub