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From: Richard Henderson <richard.henderson@linaro.org>
To: frank.chang@sifive.com, qemu-devel@nongnu.org, qemu-riscv@nongnu.org
Cc: "Chih-Min Chao" <chihmin.chao@sifive.com>,
	"Alex Bennée" <alex.bennee@linaro.org>,
	"Aurelien Jarno" <aurelien@aurel32.net>,
	"Peter Maydell" <peter.maydell@linaro.org>
Subject: Re: [PATCH v4 1/2] softfloat: add APIs to handle alternative sNaN propagation for fmax/fmin
Date: Sat, 16 Oct 2021 10:59:02 -0700	[thread overview]
Message-ID: <9dd37c01-835b-536a-c0ba-3ef23bbbfa42@linaro.org> (raw)
In-Reply-To: <20211016085428.3001501-2-frank.chang@sifive.com>

On 10/16/21 1:54 AM, frank.chang@sifive.com wrote:
> From: Chih-Min Chao<chihmin.chao@sifive.com>
> 
> For "fmax/fmin ft0, ft1, ft2" and if one of the inputs is sNaN,
> 
>    The original logic:
>      Return NaN and set invalid flag if ft1 == sNaN || ft2 == sNan.
> 
>    The alternative path:
>      Set invalid flag if ft1 == sNaN || ft2 == sNaN.
>      Return NaN only if ft1 == NaN && ft2 == NaN.
> 
> The IEEE 754 spec allows both implementation and some architecture such
> as riscv choose different defintions in two spec versions.
> (riscv-spec-v2.2 use original version, riscv-spec-20191213 changes to
>   alternative)
> 
> Signed-off-by: Chih-Min Chao<chihmin.chao@sifive.com>
> Signed-off-by: Frank Chang<frank.chang@sifive.com>
> ---
>   fpu/softfloat-parts.c.inc | 25 +++++++++++++++++++++++--
>   fpu/softfloat.c           | 19 +++++++++++++------
>   include/fpu/softfloat.h   | 10 ++++++++++
>   3 files changed, 46 insertions(+), 8 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~


  reply	other threads:[~2021-10-16 18:00 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-16  8:54 [PATCH v4 0/2] add APIs to handle alternative sNaN propagation for fmax/fmin frank.chang
2021-10-16  8:54 ` [PATCH v4 1/2] softfloat: " frank.chang
2021-10-16 17:59   ` Richard Henderson [this message]
2021-10-16  8:54 ` [PATCH v4 2/2] target/riscv: change the api for RVF/RVD fmin/fmax frank.chang
2021-10-20  2:56   ` Frank Chang
2021-10-20 23:24   ` Alistair Francis

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