From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mailgate-1.zdv.net (mailgate-1.zdv.net [IPv6:2001:4c80:40:62d::25:1]) by sourceware.org (Postfix) with ESMTPS id 738323858D33 for ; Tue, 14 Feb 2023 09:32:06 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 738323858D33 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=hs-kl.de Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=hs-kl.de X-IPAS-Result: =?us-ascii?q?A2BCBQDqU+tj/2UNXY9agQmGeQGENpByn3IPAQEBDgFEB?= =?us-ascii?q?AEBijkmOBMBAgQBAQEBAwIDAQEBAQEBAwEBAQUBAQEBAQEGAwGBHYUvRoZ/F?= =?us-ascii?q?XYCJgJfDQgBAYJ6gyOsLYEygQGEc5pmgWcJAYEKLIkViE2BVUSBPINBiByCZ?= =?us-ascii?q?wSWDIE0d4EkDoFCgQkCCQIRRyqBFghogWYlBA4DGSsdQAIBC3U/NQkNJgY/B?= =?us-ascii?q?gIPHzYGAwkDAh9Lbi4REwUDCxUqRwQINgUGUBECCA8SDyxEDkI3NBMGgQYLD?= =?us-ascii?q?hEDTYFHBIENgQJVmWVfpiagAzQHgieBUoFPBgyefgZBg2aTJwaSIZdVoiuFQ?= =?us-ascii?q?wIEAgQFAhaBeYF+MxokgzdRFwIPpmqBLwIHCwEBAwmJewGBEwEB?= IronPort-Data: A9a23:JH3EOay6GVVDxkF3DF96t+euxCrEfRIJ4+MujC+fZmUNrF6WrkUOx jMdWDrUPvmJZGf1fIoja4TjpEkC6pWEmNJqTFc/+C00HyNBpOP7XtnIdU2Y0wF+jyHgoOCLy +1EN7Es+ehtFie0Si+Fa+Sn9z8lvU2xbuKUIPbePSxsThNTRi4kiBZy88Y0mYcAbeKRWmthg vuv5ZyAULOZ82QsaDlMsfvf8EoHUMna4Vv0gHRvOJing3eG/5UlJMp3Db28KXL+Xr5VEoaSL woU5Ojklo9x105F5uKNyt4XQGVTKlLhFVHmZk5tZkSXqkMqShrecEoMHKF0hU9/011llj3qo TlHncTYpQwBZsUglAmBOvVVO3kWAEFIxFPICWKzuJGCl1zYT0vP7OpOVR0IHpQAps8iVAmi9 dRAQNwMRgKPmaSwza7TputE35h4apiwetpE/Cg4lFk1Dt5/KXzHa5rL4d9V2DJ2o81PEOz2Z 9Fcaj4pYBmojxhnYwhLV8xvxr347pX5W2NJkxGRhbc32E3OyzBswJGzPfSFIPXfEK25mW7d/ Aoq5V/RDRoRcdySzSKt/XmnwODJgGX8Qo16KVGj3vtjgVmc2TRKTh0NEFi/5/W04qKjZ+9ix 4Uv0nJGhcAPGIaDFLERgzXQTKa4gyMh IronPort-HdrOrdr: A9a23:DNteN682CT7ZUzI94cBuk+DqI+orL9Y04lQ7vn2ZESYlF/Bxl6 iV88jzpiWE7Ar5OUtQ4exoV5PwIk80maQZ3WBzB8bYYOCFghrLEGgK1+KLqFfd8kbFmNK1oJ 0BT0EIMrzN5DZB4foSqzPIdOrIiOP3lpxAq92utktQcQ== X-IronPort-Anti-Spam-Filtered: true X-IronPort-AV: E=Sophos;i="5.97,296,1669071600"; d="scan'208";a="174769228" Received: from mailgw01.hs-kl.de (HELO zdv.net) ([143.93.13.101]) by mailgate-1.zdv.net with ESMTP/TLS/AES256-GCM-SHA384; 14 Feb 2023 10:32:04 +0100 Received: from [192.168.178.62] (84.131.221.150) by klrz-mail01.ds.fh-kl.de (10.1.3.101) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.17; Tue, 14 Feb 2023 10:32:04 +0100 Message-ID: <2e0f499b-b854-bde4-ba73-e2e37c3cf334@hs-kl.de> Date: Tue, 14 Feb 2023 10:32:03 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:110.0) Gecko/20100101 Thunderbird/110.0 Content-Language: de-DE To: gcc-help From: Wilhelm Meier Subject: avr-gcc: direct register access suppresses optimization Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [84.131.221.150] X-ClientProxiedBy: klrz-mail01.ds.fh-kl.de (10.1.3.101) To klrz-mail01.ds.fh-kl.de (10.1.3.101) X-Spam-Status: No, score=-1.2 required=5.0 tests=BAYES_00,KAM_DMARC_STATUS,SPF_HELO_PASS,SPF_PASS,TXREP 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: The follwing example contains functional identicaal code: <1> uses direct register access <2> uses structure mapping But <1> suppresses the hoist/sink of the loads/stores to variable g out of the loop. In case <2> this optimization is done (and is correct). What does avr-gcc hinder to do this optimization in case <1>? #include #include static uint16_t g; int main() { for(uint8_t i = 0; i < 20; i++) { ++g; // VPORTA_DIR; // <1> suppresses optimization VPORTA.DIR; // <2> } }