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[174.21.150.71]) by smtp.gmail.com with ESMTPSA id k5sm76960pjl.50.2021.02.15.10.28.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 15 Feb 2021 10:28:34 -0800 (PST) Subject: Re: [RFC PATCH 18/42] target/mips/tx79: Introduce PEXTU[BHW] opcodes (Parallel Extend Lower) To: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , qemu-devel@nongnu.org References: <20210214175912.732946-1-f4bug@amsat.org> <20210214175912.732946-19-f4bug@amsat.org> From: Richard Henderson Message-ID: <8668c62a-89c9-0456-bc33-07527dd16d91@linaro.org> Date: Mon, 15 Feb 2021 10:28:32 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210214175912.732946-19-f4bug@amsat.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2607:f8b0:4864:20::42b; envelope-from=richard.henderson@linaro.org; helo=mail-pf1-x42b.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, NICE_REPLY_A=-0.001, 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: Thomas Huth , Aleksandar Rikalo , Fredrik Noring , Laurent Vivier , =?UTF-8?Q?Alex_Benn=c3=a9e?= , Aurelien Jarno , "Maciej W. Rozycki" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 2/14/21 9:58 AM, Philippe Mathieu-Daudé wrote: > Introduce the 'Parallel Extend Lower' opcodes: $SUBJECT s/PEXTU/PEXTL/. > + /* Lower halve */ > + for (int i = 0; i < 64 / (2 * wlen); i++) { > + tcg_gen_deposit_i64(cpu_gpr[a->rd], > + cpu_gpr[a->rd], bx, 2 * wlen * i, wlen); > + tcg_gen_deposit_i64(cpu_gpr[a->rd], > + cpu_gpr[a->rd], ax, 2 * wlen * i + wlen, wlen); > + tcg_gen_shri_i64(bx, bx, wlen); > + tcg_gen_shri_i64(ax, ax, wlen); > + } > + /* Upper halve */ > + for (int i = 0; i < 64 / (2 * wlen); i++) { > + tcg_gen_deposit_i64(cpu_gpr_hi[a->rd], > + cpu_gpr_hi[a->rd], bx, 2 * wlen * i, wlen); > + tcg_gen_deposit_i64(cpu_gpr_hi[a->rd], > + cpu_gpr_hi[a->rd], ax, 2 * wlen * i + wlen, wlen); > + tcg_gen_shri_i64(bx, bx, wlen); > + tcg_gen_shri_i64(ax, ax, wlen); > + } Right, so, this expands to (4 * 4 * 2) = 32 operations for pextlb, if deposit is supported, or ((4*2 + 2) * 4 * 2) = 80 operations if not (4 per deposit). We can do a bit better, though, exploiting parallelism. /* 5 or 8 operations, w/ or w/o deposit */ void gen_widen_b(TCGv_i64 d, TCGv_i64 s) { TCGv_i64 x = tcg_temp_new_i64(); TCGv_i64 y = tcg_temp_new_i64(); TCGv_i64 m0 = tcg_constant_i64(0x0000ff000000ff00ull); /* s = abcdefgh */ tcg_gen_deposit_i64(x, s, s, 16, 48); /* x = cdefghgh */ tcg_gen_and_i64(y, x, m); /* y = 00e000g0 */ tcg_gen_andc_i64(x, x, m0); /* x = 000f000h */ tcg_gen_shli_i64(y, y, 8); /* y = 0e000g00 */ tcg_gen_or_i64(d, x, y); /* d = 0e0f0g0h */ tcg_temp_free_i64(x); tcg_temp_free_i64(y); } /* 12 or 18 operations w/ or w/o deposit */ void gen_pextb(TCGv_i64 d, TCGv_i64 s, TCGv_i64 t) { TCGv_i64 x = tcg_temp_new_i64(); gen_widen_b(x, s); gen_widen_b(d, s); tcg_gen_shli_i64(x, x, 8); tcg_gen_or_i64(d, d, x); tcg_temp_free_i64(x); } then gen_read_gpr(s, a->rs); gen_read_gpr(t, a->rt); gen_pextb(cpu_gpr[a->rd], s, t); tcg_gen_shri_i64(s, s, 32); tcg_gen_shri_i64(t, t, 32); gen_pextb(cpu_gpr_hi[a->rd], s, t); gives you the result in 26 or 38 operations. Similarly void gen_widen_h(TCGv_i64 d, TCGv_i64 s) { TCGv_i64 x = tcg_temp_new_i64(); /* s = abcd */ tcg_gen_andi_i64(x, s, 0xffff0000u); /* x = 00c0 */ tcg_gen_deposit_i64(d, s, x, 16, 48); /* d = 0c0d */ tcg_temp_free_i64(x); } r~