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Fri, 31 Jan 2025 05:37:26 -0800 (PST) Received: from [192.168.163.227] ([50.233.235.3]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-21de33254a8sm30154945ad.246.2025.01.31.05.37.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 31 Jan 2025 05:37:25 -0800 (PST) Message-ID: <3a8cca34-bb6f-471d-a879-6e573fa00fac@linaro.org> Date: Fri, 31 Jan 2025 05:37:23 -0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 45/76] target/arm: Implement FPCR.AH semantics for scalar FMIN/FMAX To: Peter Maydell Cc: qemu-devel@nongnu.org References: <20250124162836.2332150-1-peter.maydell@linaro.org> <20250124162836.2332150-46-peter.maydell@linaro.org> <7e368ef4-a60e-4308-aeb9-ec910361c424@linaro.org> Content-Language: en-US From: Richard Henderson In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed 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: -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_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: 2.1.29 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-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 1/31/25 05:09, Peter Maydell wrote: >>> +/* >>> + * AH=1 min/max have some odd special cases: >>> + * comparing two zeroes (even of different sign), (NaN, anything), >>> + * or (anything, NaN) should return the second argument (possibly >>> + * squashed to zero). >>> + * Also, denormal outputs are not squashed to zero regardless of FZ or FZ16. >>> + */ >>> +#define AH_MINMAX_HELPER(NAME, CTYPE, FLOATTYPE, MINMAX) \ >>> + CTYPE HELPER(NAME)(CTYPE a, CTYPE b, float_status *fpst) \ >>> + { \ >>> + bool save; \ >>> + CTYPE r; \ >>> + a = FLOATTYPE ## _squash_input_denormal(a, fpst); \ >>> + b = FLOATTYPE ## _squash_input_denormal(b, fpst); \ >>> + if (FLOATTYPE ## _is_zero(a) && FLOATTYPE ## _is_zero(b)) { \ >> >> The comment says "even of different sign", the pseudocode explicitly checks different >> sign. But of course if they're the same sign a and b are indistinguishable. Perhaps >> slightly different wording? > > Sure. I changed from "(even of different sign)" to > "(regardless of sign)". Let me know if you have a > more specific tweak you'd like. Sounds good. r~