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 [216.205.24.124]) by sourceware.org (Postfix) with ESMTP id 3FE623951471 for ; Wed, 20 Jan 2021 12:19:58 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 3FE623951471 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-465-2glWLH6JMSiVT7jMC9MZ2Q-1; Wed, 20 Jan 2021 07:19:54 -0500 X-MC-Unique: 2glWLH6JMSiVT7jMC9MZ2Q-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 D6C5075BA0; Wed, 20 Jan 2021 12:19:52 +0000 (UTC) Received: from tucnak.zalov.cz (ovpn-112-64.ams2.redhat.com [10.36.112.64]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4DD8027C24; Wed, 20 Jan 2021 12:19:52 +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 10KCJnkN1585908 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Wed, 20 Jan 2021 13:19:49 +0100 Received: (from jakub@localhost) by tucnak.zalov.cz (8.16.1/8.16.1/Submit) id 10KCJlcD1585907; Wed, 20 Jan 2021 13:19:47 +0100 Date: Wed, 20 Jan 2021 13:19:47 +0100 From: Jakub Jelinek To: Richard Biener Cc: gcc-patches@gcc.gnu.org, richard.sandiford@arm.com Subject: Re: [PATCH] Handle overflow in dependence analysis lambda ops gracefully Message-ID: <20210120121947.GQ4020736@tucnak> Reply-To: Jakub Jelinek References: <20210120113358.GP4020736@tucnak> 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=us-ascii Content-Disposition: inline X-Spam-Status: No, score=-12.4 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H3, 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: Wed, 20 Jan 2021 12:19:59 -0000 On Wed, Jan 20, 2021 at 01:15:12PM +0100, Richard Biener wrote: > OK, fixed. Guess we could also use __builtin_mul_overflow directly > if supported via a GCC_VERSION check. Looks like it's present > since GCC 5 at least. So sth like (incremental) > > diff --git a/gcc/hwint.h b/gcc/hwint.h > index 53f4ed5dcad..6d2d491acfa 100644 > --- a/gcc/hwint.h > +++ b/gcc/hwint.h > @@ -354,12 +354,19 @@ add_hwi (HOST_WIDE_INT a, HOST_WIDE_INT b, bool > *overflow) > inline HOST_WIDE_INT > mul_hwi (HOST_WIDE_INT a, HOST_WIDE_INT b, bool *overflow) > { > +#if GCC_VERSION < 5001 > unsigned HOST_WIDE_INT result = a * (unsigned HOST_WIDE_INT)b; > - if (a != 0 && (HOST_WIDE_INT)result / a != b) > + if ((a == -1 && b == HOST_WIDE_INT_MIN) > + || (a != 0 && (HOST_WIDE_INT)result / a != b)) > *overflow = true; > else > *overflow = false; > return result; > +#else > + HOST_WIDE_INT result; > + *overflow = __builtin_mul_overflow (a, b, &result); > + return result; > +#endif > } > > for the add case we should match all of the function I guess. Yeah, sure. Maybe bump somewhat the GCC_VERSION number in there, we've had bugs in __builtin_mul_overflow expansion too. Jakub