From patchwork Fri Mar 11 18:12:24 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Maydell X-Patchwork-Id: 86440 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [199.232.76.165]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 31ADFB6FBB for ; Sat, 12 Mar 2011 05:13:57 +1100 (EST) Received: from localhost ([127.0.0.1]:54497 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Py6qX-0002zI-Vg for incoming@patchwork.ozlabs.org; Fri, 11 Mar 2011 13:13:54 -0500 Received: from [140.186.70.92] (port=46863 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Py6pL-0002x6-1r for qemu-devel@nongnu.org; Fri, 11 Mar 2011 13:12:40 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Py6pK-0005oP-0w for qemu-devel@nongnu.org; Fri, 11 Mar 2011 13:12:38 -0500 Received: from mnementh.archaic.org.uk ([81.2.115.146]:53506) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Py6pJ-0005kF-PZ for qemu-devel@nongnu.org; Fri, 11 Mar 2011 13:12:37 -0500 Received: from pm215 by mnementh.archaic.org.uk with local (Exim 4.72) (envelope-from ) id 1Py6p9-0005kE-2B; Fri, 11 Mar 2011 18:12:27 +0000 From: Peter Maydell To: qemu-devel@nongnu.org Date: Fri, 11 Mar 2011 18:12:24 +0000 Message-Id: <1299867146-22049-6-git-send-email-peter.maydell@linaro.org> X-Mailer: git-send-email 1.7.2.3 In-Reply-To: <1299867146-22049-1-git-send-email-peter.maydell@linaro.org> References: <1299867146-22049-1-git-send-email-peter.maydell@linaro.org> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 2) X-Received-From: 81.2.115.146 Cc: patches@linaro.org Subject: [Qemu-devel] [PATCH 5/7] target-arm: Correct ABD's handling of negative zeroes X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Implement ABD by taking the absolute value of the difference of the operands (as the ARM ARM specifies) rather than by flipping the order of the operands to the subtract based on the results of a comparison. The latter approch gives the wrong answers for some edge cases like negative zero. Signed-off-by: Peter Maydell --- target-arm/neon_helper.c | 4 +--- 1 files changed, 1 insertions(+), 3 deletions(-) diff --git a/target-arm/neon_helper.c b/target-arm/neon_helper.c index 8eb4cef..1905545 100644 --- a/target-arm/neon_helper.c +++ b/target-arm/neon_helper.c @@ -1788,9 +1788,7 @@ uint32_t HELPER(neon_abd_f32)(CPUState *env, uint32_t a, uint32_t b) { float32 f0 = make_float32(a); float32 f1 = make_float32(b); - return float32_val((float32_compare_quiet(f0, f1, NFS) == 1) - ? float32_sub(f0, f1, NFS) - : float32_sub(f1, f0, NFS)); + return float32_val(float32_abs(float32_sub(f0, f1, NFS))); } uint32_t HELPER(neon_add_f32)(CPUState *env, uint32_t a, uint32_t b)