From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46542) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cX1WU-0006HJ-TP for qemu-devel@nongnu.org; Fri, 27 Jan 2017 03:04:43 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cX1WR-0001Tz-Pq for qemu-devel@nongnu.org; Fri, 27 Jan 2017 03:04:42 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:35875) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cX1WR-0001TR-HK for qemu-devel@nongnu.org; Fri, 27 Jan 2017 03:04:39 -0500 Received: from pps.filterd (m0098409.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v0R7x2KH057746 for ; Fri, 27 Jan 2017 03:04:38 -0500 Received: from e23smtp09.au.ibm.com (e23smtp09.au.ibm.com [202.81.31.142]) by mx0a-001b2d01.pphosted.com with ESMTP id 287va9b1b8-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 27 Jan 2017 03:04:38 -0500 Received: from localhost by e23smtp09.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 27 Jan 2017 18:04:36 +1000 From: Bharata B Rao Date: Fri, 27 Jan 2017 13:33:32 +0530 In-Reply-To: <1485504213-21632-1-git-send-email-bharata@linux.vnet.ibm.com> References: <1485504213-21632-1-git-send-email-bharata@linux.vnet.ibm.com> Message-Id: <1485504213-21632-2-git-send-email-bharata@linux.vnet.ibm.com> Subject: [Qemu-devel] [RFC PATCH v2 1/2] softfloat: Handle float64 rounding properly for underflow case List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-ppc@nongnu.org, david@gibson.dropbear.id.au, rth@twiddle.net, nikunj@linux.vnet.ibm.com, peter.maydell@linaro.org, Bharata B Rao When rounding a floating point result to float64 precision, the existing code doesn't re-calculate the required round increment for the underflow case. Fix this. Signed-off-by: Bharata B Rao --- fpu/softfloat.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/fpu/softfloat.c b/fpu/softfloat.c index c295f31..b04699c 100644 --- a/fpu/softfloat.c +++ b/fpu/softfloat.c @@ -651,6 +651,23 @@ static float64 roundAndPackFloat64(flag zSign, int zExp, uint64_t zSig, if (isTiny && roundBits) { float_raise(float_flag_underflow, status); } + switch (roundingMode) { + case float_round_nearest_even: + case float_round_ties_away: + roundIncrement = 0x200; + break; + case float_round_to_zero: + roundIncrement = 0; + break; + case float_round_up: + roundIncrement = zSign ? 0 : 0x3ff; + break; + case float_round_down: + roundIncrement = zSign ? 0x3ff : 0; + break; + default: + abort(); + } } } if (roundBits) { -- 2.7.4