From patchwork Fri May 4 10:05:47 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Peter Maydell X-Patchwork-Id: 908645 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=nongnu.org (client-ip=2001:4830:134:3::11; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=linaro.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 40cnjQ5KLbz9s1d for ; Fri, 4 May 2018 20:06:33 +1000 (AEST) Received: from localhost ([::1]:33392 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fEXbh-0004kT-QP for incoming@patchwork.ozlabs.org; Fri, 04 May 2018 06:06:29 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53391) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fEXb8-0004ik-UN for qemu-devel@nongnu.org; Fri, 04 May 2018 06:05:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fEXb7-0008LV-V1 for qemu-devel@nongnu.org; Fri, 04 May 2018 06:05:54 -0400 Received: from orth.archaic.org.uk ([2001:8b0:1d0::2]:41462) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fEXb5-00085P-3i; Fri, 04 May 2018 06:05:51 -0400 Received: from pm215 by orth.archaic.org.uk with local (Exim 4.89) (envelope-from ) id 1fEXb2-0002du-P0; Fri, 04 May 2018 11:05:48 +0100 From: Peter Maydell To: qemu-arm@nongnu.org, qemu-devel@nongnu.org Date: Fri, 4 May 2018 11:05:47 +0100 Message-Id: <20180504100547.14621-1-peter.maydell@linaro.org> X-Mailer: git-send-email 2.17.0 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2001:8b0:1d0::2 Subject: [Qemu-devel] [PATCH] softfloat: Handle default NaN mode after pickNaNMulAdd, not before 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: =?utf-8?q?Alex_Benn=C3=A9e?= , qemu-stable@nongnu.org, patches@linaro.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" It is implementation defined whether a multiply-add of (0,inf,qnan) or (inf,0,qnan) raises InvalidaOperation or not, so we let the target-specific pickNaNMulAdd function handle this. This means that we must do the "return the default NaN in default NaN mode" check after the call, not before. Correct the ordering, and restore the comment from the old propagateFloat64MulAddNaN() that warned about this corner case. This fixes a regression from 2.11 for Arm guests where we would incorrectly fail to set the Invalid flag for these cases. Cc: qemu-stable@nongnu.org Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Reviewed-by: Alex Bennée Tested-by: Alex Bennée --- fpu/softfloat.c | 52 ++++++++++++++++++++++++++++--------------------- 1 file changed, 30 insertions(+), 22 deletions(-) diff --git a/fpu/softfloat.c b/fpu/softfloat.c index 70e0c40a1c..8401b37bd4 100644 --- a/fpu/softfloat.c +++ b/fpu/softfloat.c @@ -602,34 +602,42 @@ static FloatParts pick_nan(FloatParts a, FloatParts b, float_status *s) static FloatParts pick_nan_muladd(FloatParts a, FloatParts b, FloatParts c, bool inf_zero, float_status *s) { + int which; + if (is_snan(a.cls) || is_snan(b.cls) || is_snan(c.cls)) { s->float_exception_flags |= float_flag_invalid; } - if (s->default_nan_mode) { - a.cls = float_class_dnan; - } else { - switch (pickNaNMulAdd(is_qnan(a.cls), is_snan(a.cls), - is_qnan(b.cls), is_snan(b.cls), - is_qnan(c.cls), is_snan(c.cls), - inf_zero, s)) { - case 0: - break; - case 1: - a = b; - break; - case 2: - a = c; - break; - case 3: - a.cls = float_class_dnan; - return a; - default: - g_assert_not_reached(); - } + which = pickNaNMulAdd(is_qnan(a.cls), is_snan(a.cls), + is_qnan(b.cls), is_snan(b.cls), + is_qnan(c.cls), is_snan(c.cls), + inf_zero, s); - a.cls = float_class_msnan; + if (s->default_nan_mode) { + /* Note that this check is after pickNaNMulAdd so that function + * has an opportunity to set the Invalid flag. + */ + a.cls = float_class_dnan; + return a; } + + switch (which) { + case 0: + break; + case 1: + a = b; + break; + case 2: + a = c; + break; + case 3: + a.cls = float_class_dnan; + return a; + default: + g_assert_not_reached(); + } + a.cls = float_class_msnan; + return a; }