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([2602:47:d490:6901:4f6f:6b:2de4:e0cb]) by smtp.gmail.com with ESMTPSA id u3-20020a62ed03000000b00682a839d0aesm7993190pfh.112.2023.07.31.13.37.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 31 Jul 2023 13:37:23 -0700 (PDT) Message-ID: <4b38596d-1db6-e03f-8b42-65c4464132ab@linaro.org> Date: Mon, 31 Jul 2023 13:37:21 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH] disas/riscv: Further correction to LUI disassembly Content-Language: en-US To: Richard Bagley , qemu-devel@nongnu.org Cc: qemu-riscv@nongnu.org, alistair.francis@wdc.com, bmeng@tinylab.org, liweiwei@iscas.ac.cn, zhiwei_liu@linux.alibaba.com, palmer@rivosinc.com, dbarboza@ventanamicro.com References: <20230731183320.410922-1-rbagley@ventanamicro.com> From: Richard Henderson In-Reply-To: <20230731183320.410922-1-rbagley@ventanamicro.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::433; envelope-from=richard.henderson@linaro.org; helo=mail-pf1-x433.google.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 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=-0.101, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable 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 7/31/23 11:33, Richard Bagley wrote: > The recent commit 36df75a0a9 corrected one aspect of LUI disassembly > by recovering the immediate argument from the result of LUI with a > shift right by 12. However, the shift right will left-fill with the > sign. By applying a mask we recover an unsigned representation of the > 20-bit field (which includes a sign bit). Why would you want that? Surely lui r1, -1 is more accurate than lui r1, 0xfffff r~