From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:58963) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gtdnd-0000bT-LJ for qemu-devel@nongnu.org; Tue, 12 Feb 2019 14:32:58 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gtdnc-00044i-IT for qemu-devel@nongnu.org; Tue, 12 Feb 2019 14:32:57 -0500 References: <20190212110308.13707-1-david@redhat.com> <20190212110308.13707-10-david@redhat.com> <43fda672-487e-fef9-17c8-ce0657f27dbe@linaro.org> From: David Hildenbrand Message-ID: <86c01eb1-5423-cd47-1173-747a4708cf87@redhat.com> Date: Tue, 12 Feb 2019 20:32:47 +0100 MIME-Version: 1.0 In-Reply-To: <43fda672-487e-fef9-17c8-ce0657f27dbe@linaro.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v1 08/15] s390x/tcg: Handle SET FPC AND LOAD FPC 3-bit BFP rounding modes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Richard Henderson , qemu-devel@nongnu.org Cc: Thomas Huth , Janosch Frank , Cornelia Huck , Halil Pasic , Christian Borntraeger , qemu-s390x@nongnu.org, Richard Henderson On 12.02.19 20:07, Richard Henderson wrote: > On 2/12/19 3:03 AM, David Hildenbrand wrote: >> We already forward the 3 bits correctly in the translation functions. We >> also have to handle them properly and check for specification >> exceptions. >> >> Setting an invalid rounding mode (BFP only, all DFP rounding modes) >> results in a specification exception. Setting unassigned bits in the >> fpc, results in a specification exception. >> >> This fixes LOAD FPC (AND SIGNAL), SET FPC (AND SIGNAL). Also for, >> SET BFP ROUNDING MODE, 3-bit rounding mode is now explicitly checked. >> >> Notes: >> 1. Use "float_round_to_zero" for now to handle "Round to prepare for >> shorter precision". Looking at the PoP "Summary of Rounding and Range >> Actions" for BFP. They differ when it comes to tiny values. >> 2. TCG_CALL_NO_WG is required for sfpc handler, as we now inject >> exceptions. >> >> We won't be modeling abscence of the "floating-point extension facility" >> for now, not necessary as most take the facility for granted without >> checking. >> >> z14 PoP, 9-23, "LOAD FPC" >> When the floating-point extension facility is >> installed, bits 29-31 of the second operand must >> specify a valid BFP rounding mode and bits 6-7, >> 14-15, 24, and 28 must be zero; otherwise, a >> specification exception is recognized. > > > Reviewed-by: Richard Henderson > >> + /* >> + * FIXME: we actually want something like round_to_odd, but that does not >> + * support all data types yet. >> + */ >> + float_round_to_zero, > > Yes, you want round_to_odd. I suppose that's not valid for float128 right now? roundAndPackFloat64() as well as roundAndPackFloat128() support it. It's not implemented for round_canonical(), round_to_int(), roundAndPackInt32(), roundAndPackInt64(), roundAndPackUint64(), roundAndPackFloat32() (and roundAndPackFloatx80()). I assume at least 32bit is missing. I can't judge if the other functions are relevant (x80 clearly not). > > > r~ > -- Thanks, David / dhildenb