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[2603:800c:3202:ffa7:c4c7:6719:c57e:8ffe]) by smtp.gmail.com with ESMTPSA id x26sm3303870pfm.77.2021.07.30.13.00.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 30 Jul 2021 13:00:06 -0700 (PDT) Subject: Re: [PATCH for-6.2 44/53] softfloat: Remove assertion preventing silencing of NaN in default-NaN mode To: Peter Maydell , qemu-arm@nongnu.org, qemu-devel@nongnu.org References: <20210729111512.16541-1-peter.maydell@linaro.org> <20210729111512.16541-45-peter.maydell@linaro.org> From: Richard Henderson Message-ID: <8d603e08-9f6c-896f-2ad9-8b5c06291767@linaro.org> Date: Fri, 30 Jul 2021 10:00:03 -1000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210729111512.16541-45-peter.maydell@linaro.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::1032; envelope-from=richard.henderson@linaro.org; helo=mail-pj1-x1032.google.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.125, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 7/29/21 1:15 AM, Peter Maydell wrote: > In commit a777d6033447a we added an assertion to parts_silence_nan() that > prohibits calling float*_silence_nan() when in default-NaN mode. > This ties together a property of the output ("do we generate a default > NaN when the result is a NaN?") with an operation on an input ("silence > this input NaN"). > > It's true that most of the time when in default-NaN mode you won't > need to silence an input NaN, because you can just produce the > default NaN as the result instead. But some functions like > float*_maxnum() are defined to be able to work with quiet NaNs, so > silencing an input SNaN is still reasonable. In particular, the > upcoming implementation of MVE VMAXNMV would fall over this assertion > if we didn't delete it. > > Delete the assertion. > > Signed-off-by: Peter Maydell > --- > fpu/softfloat-specialize.c.inc | 1 - > 1 file changed, 1 deletion(-) Reviewed-by: Richard Henderson r~