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Sun, 12 Sep 2021 05:48:48 -0700 (PDT) Received: from [192.168.1.11] ([71.212.134.125]) by smtp.gmail.com with ESMTPSA id d18sm4779180pgk.24.2021.09.12.05.48.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 12 Sep 2021 05:48:48 -0700 (PDT) Subject: Re: [PATCH 1/4] target/arm: Add TB flag for "MVE insns not predicated" To: Peter Maydell References: <20210902150910.15748-1-peter.maydell@linaro.org> <20210902150910.15748-2-peter.maydell@linaro.org> <76cd3594-f864-232c-8687-19a1d44ff07e@linaro.org> <906c738e-904c-99ba-b6ab-2556e9262c87@linaro.org> From: Richard Henderson Message-ID: <04f9c245-4be8-47a0-6b10-8d753364b94d@linaro.org> Date: Sun, 12 Sep 2021 05:48:46 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::102d; envelope-from=richard.henderson@linaro.org; helo=mail-pj1-x102d.google.com X-Spam_score_int: -56 X-Spam_score: -5.7 X-Spam_bar: ----- X-Spam_report: (-5.7 / 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, NICE_REPLY_A=-3.584, 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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-arm , QEMU Developers Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 9/10/21 9:00 AM, Peter Maydell wrote: > We actually already have code that sets is_jmp (to DISAS_UPDATE_EXIT) > from gen_preserve_fp_state() -- we do that if we're using icount, > setting DISAS_UPDATE_EXIT to force this to be the last insn in the TB. > > Do icount IO instructions need to avoid a possible goto_tb ? > I suppose we do want them to go back to the main loop. We do want them to go back to the main loop. I'd be surprised if many (or any) io instructions are also direct branches, but... > This suggests that we need to make gen_goto_tb() look at > the is_jmp value anyway, regardless of this series. Yes. WLSTP may need to avoid the goto_tb along one path. r~