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Sun, 26 Jan 2025 04:43:58 -0800 (PST) Received: from [192.168.163.227] ([50.225.135.10]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-21da3d9e092sm45689715ad.28.2025.01.26.04.43.57 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 26 Jan 2025 04:43:57 -0800 (PST) Message-ID: <7e368ef4-a60e-4308-aeb9-ec910361c424@linaro.org> Date: Sun, 26 Jan 2025 04:43:55 -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: qemu-devel@nongnu.org References: <20250124162836.2332150-1-peter.maydell@linaro.org> <20250124162836.2332150-46-peter.maydell@linaro.org> Content-Language: en-US From: Richard Henderson In-Reply-To: <20250124162836.2332150-46-peter.maydell@linaro.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::631; envelope-from=richard.henderson@linaro.org; helo=mail-pl1-x631.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, T_SCC_BODY_TEXT_LINE=-0.01 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 1/24/25 08:28, Peter Maydell wrote: > diff --git a/target/arm/tcg/helper-a64.c b/target/arm/tcg/helper-a64.c > index 05036089dd7..406d76e1129 100644 > --- a/target/arm/tcg/helper-a64.c > +++ b/target/arm/tcg/helper-a64.c > @@ -399,6 +399,42 @@ float32 HELPER(fcvtx_f64_to_f32)(float64 a, float_status *fpst) > return r; > } > > +/* > + * 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? Anyway, Reviewed-by: Richard Henderson r~