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Thu, 19 Feb 2026 21:44:30 -0800 (PST) Received: from sifive.com ([136.226.240.194]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-824c6b6a099sm26098970b3a.33.2026.02.19.21.44.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 19 Feb 2026 21:44:29 -0800 (PST) Date: Fri, 20 Feb 2026 13:44:27 +0800 From: Max Chou To: Richard Henderson Cc: qemu-devel@nongnu.org Subject: Re: [PATCH v4 8/9] fpu: Add conversion routines for OCP FP8 E4M3 Message-ID: References: <20260205111622.461497-1-richard.henderson@linaro.org> <20260205111622.461497-9-richard.henderson@linaro.org> <695ae1da-8ca6-4966-87fa-5cd712cda59a@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <695ae1da-8ca6-4966-87fa-5cd712cda59a@linaro.org> Received-SPF: pass client-ip=2607:f8b0:4864:20::42e; envelope-from=max.chou@sifive.com; helo=mail-pf1-x42e.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: qemu development 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 2026-02-16 15:30, Richard Henderson wrote: > It doesn't feel right doing this here, because true overflow is handled > elsewhere. This is re-packing a FloatParts for a given FloatFmt. > > Perhaps parts64_float_to_float() would be the proper place for this, as > that's the conversion operation, and recognizing this overflow feels like > part of a conversion. Hmm, I agree with you. Maybe we could add a new float_to_e5m2 similar to float_to_ahp and replacing the parts_float_to_float calls in float32_to_float8_e5m2/bfloat16_to_float8_e5m2. +static void parts_float_to_e5m2(FloatParts64 *a, float_status *s, + bool saturate) +{ + switch (a->cls) { + case float_class_snan: + case float_class_qnan: + parts_return_nan(a, s); + break; + case float_class_inf: + if (saturate) { + float_raise(float_flag_invalid, s); + a->cls = float_class_normal; + a->exp = float8_e5m2_params.exp_max - 1; + a->frac = MAKE_64BIT_MASK(float8_e5m2_params.frac_shift, + float8_e5m2_params.frac_size + 1); + } + break; + case float_class_denormal: + float_raise(float_flag_input_denormal_used, s); + break; + case float_class_normal: + case float_class_zero: + break; + default: + g_assert_not_reached(); + } +} Thanks for the feedbacks, rnax