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[37.14.164.149]) by smtp.gmail.com with ESMTPSA id d8sm3994363wrv.20.2021.09.09.23.46.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 09 Sep 2021 23:46:42 -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> From: Richard Henderson Message-ID: Date: Fri, 10 Sep 2021 08:46:39 +0200 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=2a00:1450:4864:20::32e; envelope-from=richard.henderson@linaro.org; helo=mail-wm1-x32e.google.com X-Spam_score_int: -40 X-Spam_score: -4.1 X-Spam_bar: ---- X-Spam_report: (-4.1 / 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, NICE_REPLY_A=-1.975, 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 9/9/21 3:46 PM, Peter Maydell wrote: > On Fri, 3 Sept 2021 at 14:58, Richard Henderson > wrote: >> I think you need to go ahead and end the TB and resync immediately. >> Just set dc->base.is_jmp = DISAS_UPDATE_NOCHAIN instead. > > Is there a rule for when we should set is_jmp to DISAS_UPDATE_NOCHAIN, > when we should set it to DISAS_UPDATE_EXIT, and when we should call > gen_lookup_tb() ? We seem to use all three methods at various points > for "I changed some CPU state and want to end the TB"... UPDATE_EXIT is for when you need to return to the main loop; UPDATE_NOCHAIN merely avoids goto_tb. Direct use of gen_goto_ptr should be reserved for branches (which I think is already the case). r~