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[50.78.183.178]) by smtp.gmail.com with ESMTPSA id j7sm15233254pfd.129.2021.04.20.07.17.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 20 Apr 2021 07:17:42 -0700 (PDT) Subject: Re: [PATCH v2] fpu/softfloat: set invalid excp flag for RISC-V muladd instructions To: frank.chang@sifive.com, qemu-devel@nongnu.org, qemu-riscv@nongnu.org, Alistair Francis References: <20210420013150.21992-1-frank.chang@sifive.com> From: Richard Henderson Message-ID: <639de1d9-294e-9fd9-14b3-5268d45e71e0@linaro.org> Date: Tue, 20 Apr 2021 07:17:39 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <20210420013150.21992-1-frank.chang@sifive.com> 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::429; envelope-from=richard.henderson@linaro.org; helo=mail-pf1-x429.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham 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: , Cc: Peter Maydell , =?UTF-8?Q?Alex_Benn=c3=a9e?= , Aurelien Jarno Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 4/19/21 6:31 PM, frank.chang@sifive.com wrote: > From: Frank Chang > > In IEEE 754-2008 spec: > Invalid operation exception is signaled when doing: > fusedMultiplyAdd(0, Inf, c) or fusedMultiplyAdd(Inf, 0, c) > unless c is a quiet NaN; if c is a quiet NaN then it is > implementation defined whether the invalid operation exception > is signaled. > > In RISC-V Unprivileged ISA spec: > The fused multiply-add instructions must set the invalid > operation exception flag when the multiplicands are Inf and > zero, even when the addend is a quiet NaN. > > This commit set invalid operation execption flag for RISC-V when > multiplicands of muladd instructions are Inf and zero. > > Signed-off-by: Frank Chang > --- > fpu/softfloat-specialize.c.inc | 6 ++++++ > 1 file changed, 6 insertions(+) > Reviewed-by: Richard Henderson Alistair, will you take this via your riscv queue? r~