From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [207.211.31.120]) by sourceware.org (Postfix) with ESMTP id D6248385DC2E for ; Wed, 26 Aug 2020 11:34:00 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org D6248385DC2E 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-327-wNObzmgZM4O_ODiN4W8gLA-1; Wed, 26 Aug 2020 07:33:58 -0400 X-MC-Unique: wNObzmgZM4O_ODiN4W8gLA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3D167189E606; Wed, 26 Aug 2020 11:33:56 +0000 (UTC) Received: from tucnak.zalov.cz (ovpn-113-115.ams2.redhat.com [10.36.113.115]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 925597D4E5; Wed, 26 Aug 2020 11:33:55 +0000 (UTC) Received: from tucnak.zalov.cz (localhost [127.0.0.1]) by tucnak.zalov.cz (8.15.2/8.15.2) with ESMTP id 07QBXqrF004961; Wed, 26 Aug 2020 13:33:52 +0200 Received: (from jakub@localhost) by tucnak.zalov.cz (8.15.2/8.15.2/Submit) id 07QBXoh5004960; Wed, 26 Aug 2020 13:33:50 +0200 Date: Wed, 26 Aug 2020 13:33:50 +0200 From: Jakub Jelinek To: Richard Biener Cc: "Maciej W. Rozycki" , Andrew Waterman , Kito Cheng , Andreas Schwab , GCC Patches Subject: Re: [PATCH v3] libgcc: Use `-fasynchronous-unwind-tables' for LIB2_DIVMOD_FUNCS Message-ID: <20200826113350.GE2961@tucnak> Reply-To: Jakub Jelinek References: MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0.001 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Spam-Status: No, score=-7.5 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_H2, 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: Wed, 26 Aug 2020 11:34:02 -0000 On Wed, Aug 26, 2020 at 01:08:00PM +0200, Richard Biener via Gcc-patches wrote: > You only need -fexceptions for that, then you can throw; from a signal handler > for example. If you want to be able to catch the exception somewhere up > the call chain all intermediate code needs to be compiled so that unwinding > from asynchronous events is possible - -fasynchronous-unwind-tables. > > So -fasynchronous-unwind-tables is about unwinding. -f[non-call]-exceptions > is about throw/catch. Clearly libgcc does neither throw nor catch but with > async events we might need to unwind from inside it. In C code -f{,non-call-}exceptions is also about whether cleanup attribute will work or not. But I think in libgcc we don't really use it, especially not in the division/modulo code, not even indirectly from libc headers like pthread_cleanup_* macros. Jakub