From nobody Sat Nov 8 10:19:38 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1550069127991511.38471993727273; Wed, 13 Feb 2019 06:45:27 -0800 (PST) Received: from localhost ([127.0.0.1]:57897 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gtvmv-0000gq-2P for importer@patchew.org; Wed, 13 Feb 2019 09:45:25 -0500 Received: from eggs.gnu.org ([209.51.188.92]:39767) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gtvc1-0000Bs-3P for qemu-devel@nongnu.org; Wed, 13 Feb 2019 09:34:10 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gtvbv-0002PR-7W for qemu-devel@nongnu.org; Wed, 13 Feb 2019 09:34:09 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37062) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gtvbu-0002NY-Vs; Wed, 13 Feb 2019 09:34:03 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8669D1214B; Wed, 13 Feb 2019 14:34:00 +0000 (UTC) Received: from t460s.redhat.com (ovpn-116-173.ams2.redhat.com [10.36.116.173]) by smtp.corp.redhat.com (Postfix) with ESMTP id 677715D6AA; Wed, 13 Feb 2019 14:33:58 +0000 (UTC) From: David Hildenbrand To: qemu-devel@nongnu.org Date: Wed, 13 Feb 2019 15:33:21 +0100 Message-Id: <20190213143322.31371-15-david@redhat.com> In-Reply-To: <20190213143322.31371-1-david@redhat.com> References: <20190213143322.31371-1-david@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Wed, 13 Feb 2019 14:34:00 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v2 14/15] s390x/tcg: Handle all rounding modes overwritten by BFP instructions X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Thomas Huth , Janosch Frank , David Hildenbrand , Cornelia Huck , Halil Pasic , Christian Borntraeger , qemu-s390x@nongnu.org, Richard Henderson Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" PoP describes "Round to nearest with ties away from 0" as "The candidate nearest to the input value is selected. In case of a tie, the candidate selected is the one that is larger in magnitude." While float_round_ties_away is according to the introducing commit f9288a76f181 ("softfloat: Add support for ties-away rounding") "roundTiesToAway: the floating-point number nearest to the infinitely precise result shall be delivered; if the two nearest floating-point numbers bracketing an unrepresentable infinitely precise result are equally near, the one with larger magnitude shall be delivered." So this could be it if we're lucky ;) Handle "round to prepare for shorter precision" just as when setting it via SET FLOATING POINT and friends. As all instructions properly check for valid rounding modes in translate.c we can add an assert. Fix one missing empty line. Cc: Peter Maydell Reviewed-by: Richard Henderson Signed-off-by: David Hildenbrand --- target/s390x/fpu_helper.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/target/s390x/fpu_helper.c b/target/s390x/fpu_helper.c index 5e4b76f4aa..f790ec0c8e 100644 --- a/target/s390x/fpu_helper.c +++ b/target/s390x/fpu_helper.c @@ -397,14 +397,26 @@ uint32_t HELPER(cxb)(CPUS390XState *env, uint64_t ah,= uint64_t al, int s390_swap_bfp_rounding_mode(CPUS390XState *env, int m3) { int ret =3D env->fpu_status.float_rounding_mode; + switch (m3) { case 0: /* current mode */ break; case 1: - /* biased round no nearest */ + /* round to nearest with ties away from 0 */ + set_float_rounding_mode(float_round_ties_away, &env->fpu_status); + break; + case 3: + /* + * round to prepare for shorter precision + * + * FIXME: we actually want something like round_to_odd, but that + * does not support all data types yet. + */ + set_float_rounding_mode(float_round_to_zero, &env->fpu_status); + break; case 4: - /* round to nearest */ + /* round to nearest with ties to even */ set_float_rounding_mode(float_round_nearest_even, &env->fpu_status= ); break; case 5: @@ -419,6 +431,8 @@ int s390_swap_bfp_rounding_mode(CPUS390XState *env, int= m3) /* round to -inf */ set_float_rounding_mode(float_round_down, &env->fpu_status); break; + default: + g_assert_not_reached(); } return ret; } --=20 2.17.2