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[174.21.143.238]) by smtp.gmail.com with ESMTPSA id n24sm10974399pjt.47.2020.06.06.12.06.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 06 Jun 2020 12:06:27 -0700 (PDT) Subject: Re: [PATCH 2/7] softfloat: fix floatx80 remainder pseudo-denormal check for zero To: Joseph Myers , qemu-devel@nongnu.org, aurelien@aurel32.net, peter.maydell@linaro.org, alex.bennee@linaro.org, laurent@vivier.eu, pbonzini@redhat.com, rth@twiddle.net, ehabkost@redhat.com References: From: Richard Henderson Message-ID: <475fd8e6-af9f-34e7-c612-51e2958fa397@linaro.org> Date: Sat, 6 Jun 2020 12:06:25 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::442; envelope-from=richard.henderson@linaro.org; helo=mail-pf1-x442.google.com X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. 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, RCVD_IN_DNSWL_NONE=-0.0001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN 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 6/5/20 12:00 PM, Joseph Myers wrote: > The floatx80 remainder implementation ignores the high bit of the > significand when checking whether an operand (numerator) with zero > exponent is zero. This means it mishandles a pseudo-denormal > representation of 0x1p-16382L by treating it as zero. Fix this by > checking the whole significand instead. > > Signed-off-by: Joseph Myers > --- > fpu/softfloat.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Reviewed-by: Richard Henderson r~