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([2602:47:d49d:ec01:5aa4:aba1:1c91:a9b7]) by smtp.gmail.com with ESMTPSA id n14-20020a170902e54e00b001782580ce9csm6792382plf.249.2022.10.10.08.19.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 10 Oct 2022 08:19:23 -0700 (PDT) Message-ID: <91b2f7fc-df8b-bd76-88c0-93094fc6633c@linaro.org> Date: Mon, 10 Oct 2022 08:19:22 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.2.2 Subject: Re: [RISU PATCH 3/5] loongarch: Implement risugen module Content-Language: en-US To: Song Gao , qemu-devel@nongnu.org Cc: peter.maydell@linaro.org, alex.bennee@linaro.org, maobibo@loongson.cn References: <20220917074317.1410274-1-gaosong@loongson.cn> <20220917074317.1410274-4-gaosong@loongson.cn> From: Richard Henderson In-Reply-To: <20220917074317.1410274-4-gaosong@loongson.cn> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::102a; envelope-from=richard.henderson@linaro.org; helo=mail-pj1-x102a.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=-2.007, 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: 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" On 9/17/22 00:43, Song Gao wrote: > +sub write_mov_positive_ri($$) > +{ > + # Use lu12i.w and ori instruction > + my ($rd, $imm) = @_; > + my $high_20 = ($imm >> 12) & 0xfffff; > + > + if ($high_20) { > + # lu12i.w rd, si20 > + insn32(0x14000000 | $high_20 << 5 | $rd); This isn't necessarily positive -- lu12i.w sign-extends from 32-bits. > + # ori rd, rd, ui12 > + insn32(0x03800000 | ($imm & 0xfff) << 10 | $rd << 5 | $rd); > + } else { > + # ori rd, 0, ui12 > + insn32(0x03800000 | ($imm & 0xfff) << 10 | 0 << 5 | $rd); > + } > +} > + > +sub write_mov_ri($$) > +{ > + my ($rd, $imm) = @_; > + > + if ($imm < 0) { > + my $tmp = 0 - $imm ; > + write_mov_positive_ri($rd, $tmp); > + write_sub_rrr($rd, 0, $rd); > + } else { > + write_mov_positive_ri($rd, $imm); > + } > +} OTOH, I'm not sure why you'd need to split out write_mov_positive_ri and negate. I don't *think* we need to handle completely arbitrary constants. From the aarch64 code we certainly don't. I might write if ($imm >= -0x1000 && $imm <= 0xfff) { addi.w } elsif ($imm >= -0x80000000 && $imm <= 0x7fffffff) { lu12i.w ori } else { die "unhandled immediate load"; } Otherwise, Reviewed-by: Richard Henderson r~