src/cpu/kernels/softmax/generic/sve2/impl.cpp

/*
 * Copyright (c) 2021-2023 Arm Limited.
 *
 * SPDX-License-Identifier: MIT
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include "src/cpu/kernels/softmax/generic/sve2/impl.h"

#include "arm_compute/core/Types.h"

#include "src/core/NEON/wrapper/wrapper.h"

namespace arm_compute
{
namespace cpu
{
/// TODO: (COMPMID-6505) Similar to Neon(TM), this implementation be converted to
/// a single kernel that performs softmax operation. Leaving the SVE2 code here for
/// future references. Implementation for Neon(TM) is introduced in COMPMID-6500
template <typename ScalarType>
void sve2_softmax_logits_1d_quantized(
    const ITensor *in, const ITensor *max, void *const tmp, ITensor *out, float beta, bool is_log, const Window &window)
{
    const int start_x     = in->info()->valid_region().anchor.x();
    const int input_width = in->info()->valid_region().shape.x();

    const float scale_beta     = -beta * in->info()->quantization_info().uniform().scale;
    const auto  scale_beta_vec = svdup_n_f32(scale_beta);

    Iterator   in_it(in, window);
    Iterator   max_it(max, window);
    Iterator   out_it(out, window);
    const auto all_true_pg = wrapper::svptrue<ScalarType>();
    using SVEType          = typename wrapper::traits::sve_vector<ScalarType>::type;

    const int inc_1 = static_cast<int>(svcntw());
    const int inc_2 = static_cast<int>(2 * svcntw());
    const int inc_3 = static_cast<int>(3 * svcntw());

    execute_window_loop(
        window,
        [&](const Coordinates &)
        {
            /* Get pointers */
            const auto in_ptr  = reinterpret_cast<const ScalarType *>(in_it.ptr()) + start_x;
            const auto out_ptr = reinterpret_cast<ScalarType *>(out_it.ptr()) + start_x;
            const auto tmp_ptr = reinterpret_cast<float *>(tmp);

            float sum{};

            /* Compute exponentials and sum */
            {
                /* Get max value */
                const auto max_val = *reinterpret_cast<const ScalarType *>(max_it.ptr());
                const auto vec_max = wrapper::svdup_n(max_val);

                /* Init sum to zero */
                auto vec_sum_0 = svdup_n_f32(0.f);
                auto vec_sum_1 = svdup_n_f32(0.f);
                auto vec_sum_2 = svdup_n_f32(0.f);
                auto vec_sum_3 = svdup_n_f32(0.f);

                /* Loop over row and compute exponentials and sum */
                int      x    = 0;
                svbool_t pg   = wrapper::svwhilelt<ScalarType>(x, input_width);
                svbool_t pg_0 = svunpklo(svunpklo(pg));
                svbool_t pg_1 = svunpkhi(svunpklo(pg));
                svbool_t pg_2 = svunpklo(svunpkhi(pg));
                svbool_t pg_3 = svunpkhi(svunpkhi(pg));
                do
                {
                    const auto vec_elements     = svld1(pg, in_ptr + x);
                    const auto vec_elements_sub = svreinterpret_u8(svsub_z(pg, vec_max, vec_elements));

                    auto vec_elements_flt_0 = svcvt_f32_z(pg_0, svunpklo(svunpklo(vec_elements_sub)));
                    auto vec_elements_flt_1 = svcvt_f32_z(pg_1, svunpkhi(svunpklo(vec_elements_sub)));
                    auto vec_elements_flt_2 = svcvt_f32_z(pg_2, svunpklo(svunpkhi(vec_elements_sub)));
                    auto vec_elements_flt_3 = svcvt_f32_z(pg_3, svunpkhi(svunpkhi(vec_elements_sub)));

                    if (is_log)
                    {
                        vec_elements_flt_0 = svmul_f32_z(pg_0, vec_elements_flt_0, scale_beta_vec);
                        vec_elements_flt_1 = svmul_f32_z(pg_1, vec_elements_flt_1, scale_beta_vec);
                        vec_elements_flt_2 = svmul_f32_z(pg_2, vec_elements_flt_2, scale_beta_vec);
                        vec_elements_flt_3 = svmul_f32_z(pg_3, vec_elements_flt_3, scale_beta_vec);
                        vec_sum_0          = svadd_f32_m(pg_0, vec_sum_0, svexp_f32_z(pg_0, vec_elements_flt_0));
                        vec_sum_1          = svadd_f32_m(pg_1, vec_sum_1, svexp_f32_z(pg_1, vec_elements_flt_1));
                        vec_sum_2          = svadd_f32_m(pg_2, vec_sum_2, svexp_f32_z(pg_2, vec_elements_flt_2));
                        vec_sum_3          = svadd_f32_m(pg_3, vec_sum_3, svexp_f32_z(pg_3, vec_elements_flt_3));
                    }
                    else
                    {
                        vec_elements_flt_0 = svexp_f32_z(pg_0, svmul_f32_z(pg_0, vec_elements_flt_0, scale_beta_vec));
                        vec_elements_flt_1 = svexp_f32_z(pg_1, svmul_f32_z(pg_1, vec_elements_flt_1, scale_beta_vec));
                        vec_elements_flt_2 = svexp_f32_z(pg_2, svmul_f32_z(pg_2, vec_elements_flt_2, scale_beta_vec));
                        vec_elements_flt_3 = svexp_f32_z(pg_3, svmul_f32_z(pg_3, vec_elements_flt_3, scale_beta_vec));
                        vec_sum_0          = svadd_f32_m(pg_0, vec_sum_0, vec_elements_flt_0);
                        vec_sum_1          = svadd_f32_m(pg_1, vec_sum_1, vec_elements_flt_1);
                        vec_sum_2          = svadd_f32_m(pg_2, vec_sum_2, vec_elements_flt_2);
                        vec_sum_3          = svadd_f32_m(pg_3, vec_sum_3, vec_elements_flt_3);
                    }

                    svst1_f32(pg_0, tmp_ptr + x, vec_elements_flt_0);
                    svst1_f32(pg_1, tmp_ptr + x + inc_1, vec_elements_flt_1);
                    svst1_f32(pg_2, tmp_ptr + x + inc_2, vec_elements_flt_2);
                    svst1_f32(pg_3, tmp_ptr + x + inc_3, vec_elements_flt_3);

                    x += wrapper::svcnt<ScalarType>();
                    pg   = wrapper::svwhilelt<ScalarType>(x, input_width);
                    pg_0 = svunpklo(svunpklo(pg));
                    pg_1 = svunpkhi(svunpklo(pg));
                    pg_2 = svunpklo(svunpkhi(pg));
                    pg_3 = svunpkhi(svunpkhi(pg));
                } while (svptest_any(all_true_pg, pg));

                /* Reduce sum */
                const auto vec_sum = svadd_f32_z(all_true_pg, svadd_f32_z(all_true_pg, vec_sum_0, vec_sum_1),
                                                 svadd_f32_z(all_true_pg, vec_sum_2, vec_sum_3));
                sum                = svaddv_f32(all_true_pg, vec_sum);

                /* Run remaining elements */
                x = 0;
                if (is_log)
                {
                    sum = std::log(sum);
                }
                else
                {
                    sum = 256.f / sum;
                }
            }

            /* Normalize exponentials */
            {
                constexpr bool is_qasymm8_signed = std::is_same<ScalarType, qasymm8_signed_t>::value;
                /* Loop over row and compute softmax */
                int      x    = 0;
                svbool_t pg   = wrapper::svwhilelt<ScalarType>(x, input_width);
                svbool_t pg_0 = svunpklo(svunpklo(pg));
                svbool_t pg_1 = svunpkhi(svunpklo(pg));
                svbool_t pg_2 = svunpklo(svunpkhi(pg));
                svbool_t pg_3 = svunpkhi(svunpkhi(pg));
                do
                {
                    auto vec_in_0 = svld1_f32(pg_0, tmp_ptr + x);
                    auto vec_in_1 = svld1_f32(pg_1, tmp_ptr + x + inc_1);
                    auto vec_in_2 = svld1_f32(pg_2, tmp_ptr + x + inc_2);
                    auto vec_in_3 = svld1_f32(pg_3, tmp_ptr + x + inc_3);

                    svfloat32_t res_0{};
                    svfloat32_t res_1{};
                    svfloat32_t res_2{};
                    svfloat32_t res_3{};

                    if (is_log)
                    {
                        res_0 = svsub_f32_z(pg_0, vec_in_0, svdup_n_f32(sum));
                        res_1 = svsub_f32_z(pg_1, vec_in_1, svdup_n_f32(sum));
                        res_2 = svsub_f32_z(pg_2, vec_in_2, svdup_n_f32(sum));
                        res_3 = svsub_f32_z(pg_3, vec_in_3, svdup_n_f32(sum));
                    }
                    else
                    {
                        res_0 = svmul_f32_z(pg_0, vec_in_0, svdup_n_f32(sum));
                        res_1 = svmul_f32_z(pg_1, vec_in_1, svdup_n_f32(sum));
                        res_2 = svmul_f32_z(pg_2, vec_in_2, svdup_n_f32(sum));
                        res_3 = svmul_f32_z(pg_3, vec_in_3, svdup_n_f32(sum));

                        if (is_qasymm8_signed)
                        {
                            const auto offset_vec = svdup_n_f32(128.f);
                            res_0                 = svsub_z(pg_0, res_0, offset_vec);
                            res_1                 = svsub_z(pg_1, res_1, offset_vec);
                            res_2                 = svsub_z(pg_2, res_2, offset_vec);
                            res_3                 = svsub_z(pg_3, res_3, offset_vec);
                        }
                    }

                    // Store value
                    const auto out = convert_float_to_int<SVEType>(res_0, res_1, res_2, res_3);
                    svst1(pg, out_ptr + x, out);
                    x += wrapper::svcnt<ScalarType>();
                    pg   = wrapper::svwhilelt<ScalarType>(x, input_width);
                    pg_0 = svunpklo(svunpklo(pg));
                    pg_1 = svunpkhi(svunpklo(pg));
                    pg_2 = svunpklo(svunpkhi(pg));
                    pg_3 = svunpkhi(svunpkhi(pg));
                } while (svptest_any(all_true_pg, pg));
            }
        },
        in_it, max_it, out_it);
}
} // namespace cpu
} // namespace arm_compute