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Thu, 16 Apr 2026 03:28:08 -0700 (PDT) Received: from sifive.com ([136.226.240.165]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2b4780ef741sm49410425ad.11.2026.04.16.03.28.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Apr 2026 03:28:07 -0700 (PDT) Date: Thu, 16 Apr 2026 18:28:04 +0800 From: Max Chou To: Chao Liu Cc: qemu-devel@nongnu.org, qemu-riscv@nongnu.org, Palmer Dabbelt , Alistair Francis , Daniel Henrique Barboza , Weiwei Li , Liu Zhiwei Subject: Re: [PATCH v4 12/14] target/riscv: rvv: Add vfext.vf2 instruction for Zvfofp4min extension Message-ID: References: <20260304134006.2908449-1-max.chou@sifive.com> <20260304134006.2908449-13-max.chou@sifive.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Received-SPF: pass client-ip=2607:f8b0:4864:20::634; envelope-from=max.chou@sifive.com; helo=mail-pl1-x634.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 2026-03-04 23:13, Chao Liu wrote: > > +static bool trans_vfext_vf2(DisasContext *s, arg_rmr *a) > > +{ > > + if (vext_zvfofp4min_check(s, a)) { > Missing REQUIRE_FPU here. > > All other FP vector instruction translation functions > in this series (trans_vfncvtbf16_sat_f_f_w, trans_vfncvt_f_f_q, > trans_vfncvt_sat_f_f_q, trans_vfwcvtbf16_f_f_v, > trans_vfncvtbf16_f_f_w) have REQUIRE_FPU at the top. > > Without it, this instruction could execute even when FPU > is disabled. According to the Zvfofp4min specification, "The vfext.vf2 instruction does not access the fcsr and is not considered a floating-point instruction for the purposes of the floating-point context status (FS) settings." As a result, the vfext.vf2 instruction will not raise an illegal instruction exception when the mstatus.fs flag is disabled. rnax