src/runtime/NEON/functions/NEGEMMLowpMatrixMultiplyCore.cpp

/*
 * Copyright (c) 2017-2019 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 "arm_compute/runtime/NEON/functions/NEGEMMLowpMatrixMultiplyCore.h"

#include "arm_compute/core/Error.h"
#include "arm_compute/core/Helpers.h"
#include "arm_compute/core/ITensor.h"
#include "arm_compute/core/NEON/kernels/NEGEMMInterleave4x4Kernel.h"
#include "arm_compute/core/NEON/kernels/NEGEMMLowpMatrixMultiplyKernel.h"
#include "arm_compute/core/NEON/kernels/NEGEMMTranspose1xWKernel.h"
#include "arm_compute/core/TensorInfo.h"
#include "arm_compute/core/Types.h"
#include "arm_compute/core/Validate.h"
#include "arm_compute/core/utils/misc/ShapeCalculator.h"
#include "arm_compute/runtime/NEON/NEScheduler.h"
#include "arm_compute/runtime/TensorAllocator.h"
#include "support/ToolchainSupport.h"

using namespace arm_compute;
using namespace arm_compute::misc::shape_calculator;

NEGEMMLowpMatrixMultiplyCore::NEGEMMLowpMatrixMultiplyCore(std::shared_ptr<IMemoryManager> memory_manager)
    : _memory_group(memory_manager), _asm_glue(memory_manager), _mm_kernel(nullptr), _mtx_a_reshape_kernel(nullptr), _mtx_b_reshape_kernel(nullptr), _mtx_a_reduction_kernel(), _mtx_b_reduction_kernel(),
      _offset_contribution_kernel(), _offset_contribution_output_stage_kernel(), _activation_func(), _convert_to_signed_asymm(), _convert_from_signed_asymm(), _vector_sum_col(), _vector_sum_row(), _tmp_a(),
      _tmp_b(), _mm_result_s32(), _signed_a(), _signed_output(), _original_b(nullptr), _a_offset(0), _b_offset(0), _run_vector_matrix_multiplication(false), _assembly_path(false),
      _fused_assembly_path(false), _reshape_b_only_on_first_run(false), _is_prepared(false), _fuse_output_stage(false), _run_activation(false), _flip_signedness(false)
{
}

void NEGEMMLowpMatrixMultiplyCore::configure(const ITensor *a, const ITensor *b, const ITensor *c, ITensor *output, const GEMMInfo &gemm_info)
{
    ARM_COMPUTE_ERROR_ON_NULLPTR(a, b, output);
    ARM_COMPUTE_UNUSED(c);
    ARM_COMPUTE_ERROR_THROW_ON(NEGEMMLowpMatrixMultiplyCore::validate(a->info(), b->info(), c != nullptr ? c->info() : nullptr, output->info(), gemm_info));

    const ITensor *matrix_a = a;
    const ITensor *matrix_b = b;
    GEMMInfo       info     = gemm_info;

    // Clear state
    _mtx_a_reshape_kernel = nullptr;
    _mtx_b_reshape_kernel = nullptr;

    // Set internal variables
    _a_offset                         = a->info()->quantization_info().uniform().offset;
    _b_offset                         = b->info()->quantization_info().uniform().offset;
    _run_vector_matrix_multiplication = a->info()->dimension(1) < 2;
    _reshape_b_only_on_first_run      = info.reshape_b_only_on_first_run();
    _is_prepared                      = false;
    _fused_assembly_path              = false;
    _flip_signedness                  = is_data_type_quantized_per_channel(b->info()->data_type()) && (a->info()->data_type() == DataType::QASYMM8) && _reshape_b_only_on_first_run;
    _original_b                       = b;

    const ITensor *a_to_use = a;

    // Convert to QASYMM8 -> QASYMM8_SIGNED and back
    if(_flip_signedness)
    {
        const int32_t                 offset_correction = 128;
        const DataType                dt                = DataType::QASYMM8_SIGNED;
        const UniformQuantizationInfo iqinfo            = a_to_use->info()->quantization_info().uniform();

        _signed_a.allocator()->init(a_to_use->info()->clone()->set_data_type(dt).set_quantization_info(QuantizationInfo(iqinfo.scale, iqinfo.offset + offset_correction)));
        _memory_group.manage(&_signed_a);
        _convert_to_signed_asymm.configure(a_to_use, &_signed_a);
        a_to_use  = &_signed_a;
        _a_offset = _signed_a.info()->quantization_info().uniform().offset;

        const UniformQuantizationInfo oqinfo = output->info()->quantization_info().uniform();
        _memory_group.manage(&_signed_output);
        _signed_output.allocator()->init(output->info()->clone()->set_data_type(dt).set_quantization_info(QuantizationInfo(oqinfo.scale, oqinfo.offset - offset_correction)));

        // Output stage correction
        GEMMLowpOutputStageInfo output_stage_corr = info.gemmlowp_output_stage();
        output_stage_corr.gemmlowp_offset         = _signed_output.info()->quantization_info().uniform().offset;
        output_stage_corr.gemmlowp_min_bound -= offset_correction;
        output_stage_corr.gemmlowp_max_bound -= offset_correction;
        info.set_gemmlowp_output_stage(output_stage_corr);

        // Update matrix a
        matrix_a = &_signed_a;
    }

    // If GEMMLowpOutputStage != NONE, fuse the offset contribution with the output stage
    if(info.gemmlowp_output_stage().type != GEMMLowpOutputStageType::NONE)
    {
        _fuse_output_stage = true;
        _memory_group.manage(&_mm_result_s32);
        TensorInfo info_mm_result_s32(output->info()->tensor_shape(), 1, DataType::S32);
        _mm_result_s32.allocator()->init(info_mm_result_s32);
    }

#ifdef __aarch64__
    switch(a->info()->data_type())
    {
        case DataType::QASYMM8:
        case DataType::QASYMM8_SIGNED:
        case DataType::U8:
        case DataType::S8:
        {
            if(a_to_use->info()->data_type() == DataType::QASYMM8 && info.gemmlowp_output_stage().type == GEMMLowpOutputStageType::QUANTIZE_DOWN_FIXEDPOINT)
            {
                _asm_glue.configure(a_to_use, b, c, output, gemm_info);
                _fused_assembly_path = _asm_glue.is_configured();
            }
            else
            {
                _asm_glue.configure(a_to_use, b, nullptr, _fuse_output_stage ? &_mm_result_s32 : output, gemm_info);
            }
            _assembly_path = _asm_glue.is_configured();
            break;
        }
        default:
        {
            ARM_COMPUTE_ERROR("Datatype not supported");
            break;
        }
    }
#endif /* __aarch64__ */
    if(!(_assembly_path || _run_vector_matrix_multiplication))
    {
        matrix_a = &_tmp_a;
        matrix_b = &_tmp_b;

        // The interleaved output matrix will have the following shape: [ a_height * 4, ceil(a_width / 4.0f) ]
        TensorInfo a_info(compute_interleaved_shape(*a_to_use->info()), 1, a_to_use->info()->data_type(), a_to_use->info()->quantization_info());
        // The transpose1xW output matrix will have the following shape: [ b_height * 16, ceil(b_width / 16.0f) ]
        TensorInfo b_info(compute_transpose1xW_shape(*b->info()), 1, b->info()->data_type(), b->info()->quantization_info());
        _tmp_a.allocator()->init(a_info);
        _tmp_b.allocator()->init(b_info);
        _memory_group.manage(&_tmp_a);
        if(!_reshape_b_only_on_first_run)
        {
            _memory_group.manage(&_tmp_b);
        }

        // Configure interleave kernel
        {
            auto k = arm_compute::support::cpp14::make_unique<NEGEMMInterleave4x4Kernel>();
            k->configure(a_to_use, &_tmp_a);
            _mtx_a_reshape_kernel = std::move(k);
        }

        // Configure transpose kernel
        {
            auto k = arm_compute::support::cpp14::make_unique<NEGEMMTranspose1xWKernel>();
            k->configure(b, &_tmp_b);
            _mtx_b_reshape_kernel = std::move(k);
        }
    }

    if(!_fused_assembly_path)
    {
        // Initialize matrix B reduction kernel only if _a_offset is not equal to 0
        if(_a_offset != 0)
        {
            TensorInfo info_vector_sum_col(compute_reductionA_shape(*b->info()), 1, DataType::S32);

            _vector_sum_col.allocator()->init(info_vector_sum_col);
            if(!_reshape_b_only_on_first_run)
            {
                _memory_group.manage(&_vector_sum_col);
            }

            // Configure Matrix B reduction kernel
            _mtx_b_reduction_kernel.configure(b, &_vector_sum_col, a_to_use->info()->dimension(0), false);
        }

        // Initialize Matrix A reduction kernel only if _b_offset is not equal to 0
        if(_b_offset != 0)
        {
            TensorInfo info_vector_sum_row(compute_reductionB_shape(*a_to_use->info()), 1, DataType::S32);

            _vector_sum_row.allocator()->init(info_vector_sum_row);
            _memory_group.manage(&_vector_sum_row);

            // Configure matrix A reduction kernel
            _mtx_a_reduction_kernel.configure(a_to_use, &_vector_sum_row, a_to_use->info()->dimension(0), false);
        }

        if(_fuse_output_stage)
        {
            // Configure matrix multiply kernel
            if(!_assembly_path)
            {
                auto k = arm_compute::support::cpp14::make_unique<NEGEMMLowpMatrixMultiplyKernel>();
                k->configure(matrix_a, matrix_b, &_mm_result_s32);
                _mm_kernel = std::move(k);
            }

            _offset_contribution_output_stage_kernel.configure(&_mm_result_s32,
                                                               _a_offset == 0 ? nullptr : &_vector_sum_col,
                                                               _b_offset == 0 ? nullptr : &_vector_sum_row, c,
                                                               _flip_signedness ? &_signed_output : output,
                                                               a->info()->dimension(0),
                                                               _a_offset, _b_offset, info.gemmlowp_output_stage());

            if(_flip_signedness)
            {
                _convert_from_signed_asymm.configure(&_signed_output, output);
            }
        }
        else
        {
            // Configure matrix multiply kernel
            if(!_assembly_path)
            {
                auto k = arm_compute::support::cpp14::make_unique<NEGEMMLowpMatrixMultiplyKernel>();
                k->configure(matrix_a, matrix_b, output);
                _mm_kernel = std::move(k);
            }
            // Configure offset contribution kernel
            _offset_contribution_kernel.configure(output, _a_offset == 0 ? nullptr : &_vector_sum_col, _b_offset == 0 ? nullptr : &_vector_sum_row, a_to_use->info()->dimension(0), _a_offset, _b_offset);
        }
    }

    // Configure activation
    const ActivationLayerInfo &activation = gemm_info.activation_info();
    _run_activation                       = activation.enabled() && (!_assembly_path || (_assembly_path && !NEGEMMAssemblyDispatch::is_activation_supported(activation)));
    if(_run_activation)
    {
        _activation_func.configure(output, nullptr, activation);
    }

    // Allocate tensors
    if(!_assembly_path && !_run_vector_matrix_multiplication)
    {
        _tmp_a.allocator()->allocate();
        if(!_reshape_b_only_on_first_run)
        {
            _tmp_b.allocator()->allocate();
        }
    }

    if(!_fused_assembly_path)
    {
        if(_a_offset != 0 && !_reshape_b_only_on_first_run)
        {
            _vector_sum_col.allocator()->allocate();
        }

        if(_b_offset != 0)
        {
            _vector_sum_row.allocator()->allocate();
        }
    }

    if(_fuse_output_stage)
    {
        _mm_result_s32.allocator()->allocate();
    }

    if(_flip_signedness)
    {
        _signed_a.allocator()->allocate();
        _signed_output.allocator()->allocate();
    }
}

Status NEGEMMLowpMatrixMultiplyCore::validate(const ITensorInfo *a, const ITensorInfo *b, const ITensorInfo *c, const ITensorInfo *output, const GEMMInfo &gemm_info)
{
    ARM_COMPUTE_RETURN_ERROR_ON_DATA_TYPE_CHANNEL_NOT_IN(a, 1, DataType::QASYMM8);
    ARM_COMPUTE_RETURN_ERROR_ON_DATA_TYPE_CHANNEL_NOT_IN(b, 1, DataType::QASYMM8, DataType::QSYMM8_PER_CHANNEL);
    ARM_COMPUTE_RETURN_ERROR_ON_DATA_TYPE_CHANNEL_NOT_IN(output, 1, DataType::S32, DataType::QASYMM8);
    ARM_COMPUTE_RETURN_ERROR_ON_MSG(c != nullptr && gemm_info.gemmlowp_output_stage().type == GEMMLowpOutputStageType::NONE, "Bias addition not supported in NEGEMMLowpMatrixMultiplyCore for output S32");
    ARM_COMPUTE_RETURN_ERROR_ON_MSG((a)->dimension(0) != (b)->dimension(1),
                                    "The product AB is defined only if the number of columns in A is equal to the number of rows in B");
    ARM_COMPUTE_RETURN_ERROR_ON_MSG(gemm_info.is_a_reshaped(), "Matrix A already reshaped is not supported");
    ARM_COMPUTE_RETURN_ERROR_ON_MSG(gemm_info.is_b_reshaped(), "Matrix B already reshaped is not supported");

    GEMMInfo           info          = gemm_info;
    const ITensorInfo *matrix_a_info = a;
    const ITensorInfo *matrix_b_info = b;

    const ITensorInfo *a_to_use = a;

    TensorInfo tmp_a_info{};
    TensorInfo tmp_b_info{};
    TensorInfo mm_result_s32_info{};

    int32_t a_offset = a->quantization_info().uniform().offset;
    int32_t b_offset = b->quantization_info().uniform().offset;

    bool fuse_output_stage = info.gemmlowp_output_stage().type != GEMMLowpOutputStageType::NONE;
    if(fuse_output_stage)
    {
        auto_init_if_empty(mm_result_s32_info, a->clone()->set_tensor_shape(output->tensor_shape()).set_data_type(DataType::S32));
    }

    // Convert QASYMM8->QASYMM8_SIGNED
    TensorInfo signed_a{};
    TensorInfo signed_output{};
    bool       flip_signedness = is_data_type_quantized_per_channel(b->data_type()) && (a->data_type() == DataType::QASYMM8) && info.reshape_b_only_on_first_run();
    if(flip_signedness)
    {
        const int32_t                 offset_correction = 128;
        const DataType                dt                = DataType::QASYMM8_SIGNED;
        const UniformQuantizationInfo iqinfo            = a_to_use->quantization_info().uniform();

        signed_a = a_to_use->clone()->set_data_type(dt).set_quantization_info(QuantizationInfo(iqinfo.scale, iqinfo.offset + offset_correction));
        ARM_COMPUTE_RETURN_ON_ERROR(NEConvertQuantizedSignednessKernel::validate(a_to_use, &signed_a));
        a_to_use = &signed_a;
        a_offset = signed_a.quantization_info().uniform().offset;

        const UniformQuantizationInfo oqinfo = output->quantization_info().uniform();
        signed_output                        = output->clone()->set_data_type(dt).set_quantization_info(QuantizationInfo(oqinfo.scale, oqinfo.offset - offset_correction));

        // Output stage correction
        GEMMLowpOutputStageInfo output_stage_corr = info.gemmlowp_output_stage();
        output_stage_corr.gemmlowp_offset         = signed_output.quantization_info().uniform().offset;
        output_stage_corr.gemmlowp_min_bound -= offset_correction;
        output_stage_corr.gemmlowp_max_bound -= offset_correction;
        info.set_gemmlowp_output_stage(output_stage_corr);

        // Update matrix a
        matrix_a_info = &signed_a;
    }

    // Check if we need to run the optimized assembly kernel
    bool run_optimised             = false;
    bool run_optimised_requantized = false;
    if(a_to_use->data_type() == DataType::QASYMM8 && info.gemmlowp_output_stage().type == GEMMLowpOutputStageType::QUANTIZE_DOWN_FIXEDPOINT)
    {
        run_optimised             = bool(NEGEMMAssemblyDispatch::validate(a_to_use, b, c, output, gemm_info));
        run_optimised_requantized = run_optimised;
    }
    else
    {
        run_optimised = bool(NEGEMMAssemblyDispatch::validate(a_to_use, b, nullptr, fuse_output_stage ? &mm_result_s32_info : output, gemm_info));
    }

    if(run_optimised)
    {
        ARM_COMPUTE_RETURN_ERROR_ON(b->dimension(0) != output->dimension(0));
        if(info.depth_output_gemm3d() != 0)
        {
            if(info.reinterpret_input_as_3d())
            {
                ARM_COMPUTE_RETURN_ERROR_ON(a->dimension(1) != output->dimension(1));
                ARM_COMPUTE_RETURN_ERROR_ON(a->dimension(2) != output->dimension(2));
            }
            else
            {
                ARM_COMPUTE_RETURN_ERROR_ON(a->dimension(1) != output->dimension(1) * output->dimension(2));
            }
        }
        else
        {
            ARM_COMPUTE_RETURN_ERROR_ON(a->dimension(1) != output->dimension(1));
        }
    }
    else
    {
        ARM_COMPUTE_RETURN_ERROR_ON_MSG(info.reinterpret_input_as_3d(), "NEGEMM cannot reinterpret the input tensor as 3D");
        ARM_COMPUTE_RETURN_ERROR_ON_MSG(info.depth_output_gemm3d() != 0, "NEGEMM cannot reinterpret the output tensor as 3D");

        const bool run_vector_matrix_multiplication = a->dimension(1) < 2;
        if(!run_vector_matrix_multiplication)
        {
            matrix_a_info = &tmp_a_info;
            matrix_b_info = &tmp_b_info;

            // The interleaved output matrix will have the following shape: [ a_height * 4, ceil(a_width / 4.0f) ]
            TensorShape shape_tmp_a = a->tensor_shape();
            shape_tmp_a.set(0, a->dimension(0) * 4);
            shape_tmp_a.set(1, std::ceil(a->dimension(1) / 4.f));

            // The transpose1xW output matrix will have the following shape: [ b_height * 16, ceil(b_width / 16.0f) ]
            TensorShape shape_tmp_b = b->tensor_shape();
            shape_tmp_b.set(0, b->dimension(1) * 16);
            shape_tmp_b.set(1, std::ceil(b->dimension(0) / 16.f));

            // Validate interleave kernel
            auto_init_if_empty(tmp_a_info, a_to_use->clone()->set_tensor_shape(shape_tmp_a));
            auto_init_if_empty(tmp_b_info, b->clone()->set_tensor_shape(shape_tmp_b));

            ARM_COMPUTE_RETURN_ON_ERROR(NEGEMMInterleave4x4Kernel::validate(a_to_use, &tmp_a_info));
            ARM_COMPUTE_RETURN_ON_ERROR(NEGEMMTranspose1xWKernel::validate(b, &tmp_b_info));
        }
    }

    if(!run_optimised_requantized)
    {
        TensorInfo info_vector_sum_col{};
        TensorInfo info_vector_sum_row{};

        // Validate matrix B reduction kernel only if _a_offset is not equal to 0
        if(a_offset != 0)
        {
            info_vector_sum_col = TensorInfo(compute_reductionA_shape(*b), 1, DataType::S32);

            // Configure Matrix B reduction kernel
            ARM_COMPUTE_RETURN_ON_ERROR(NEGEMMLowpMatrixBReductionKernel::validate(b, &info_vector_sum_col, a->dimension(0), false));
        }

        // Validate Matrix A reduction kernel only if _b_offset is not equal to 0
        if(b_offset != 0)
        {
            info_vector_sum_row = TensorInfo(compute_reductionB_shape(*a), 1, DataType::S32);

            // Configure matrix A reduction kernel
            ARM_COMPUTE_RETURN_ON_ERROR(NEGEMMLowpMatrixAReductionKernel::validate(a_to_use, &info_vector_sum_row, a->dimension(0), false));
        }

        if(fuse_output_stage)
        {
            if(!run_optimised)
            {
                ARM_COMPUTE_RETURN_ON_ERROR(NEGEMMLowpMatrixMultiplyKernel::validate(matrix_a_info, matrix_b_info, &mm_result_s32_info));
            }

            // Validate offset contribution kernel
            ARM_COMPUTE_RETURN_ON_ERROR(NEGEMMLowpOffsetContributionOutputStageKernel::validate(&mm_result_s32_info,
                                                                                                a_offset == 0 ? nullptr : &info_vector_sum_col,
                                                                                                b_offset == 0 ? nullptr : &info_vector_sum_row,
                                                                                                c,
                                                                                                flip_signedness ? &signed_output : output,
                                                                                                a_offset, b_offset,
                                                                                                info.gemmlowp_output_stage()));
        }
        else
        {
            if(!run_optimised)
            {
                ARM_COMPUTE_RETURN_ON_ERROR(NEGEMMLowpMatrixMultiplyKernel::validate(matrix_a_info, matrix_b_info, output));
            }
            // Validate offset contribution kernel
            ARM_COMPUTE_RETURN_ON_ERROR(NEGEMMLowpOffsetContributionKernel::validate(output,
                                                                                     a_offset == 0 ? nullptr : &info_vector_sum_col,
                                                                                     b_offset == 0 ? nullptr : &info_vector_sum_row,
                                                                                     a_offset, b_offset));
        }
    }

    // Validate activation
    const ActivationLayerInfo &activation = gemm_info.activation_info();
    if(activation.enabled())
    {
        ARM_COMPUTE_RETURN_ON_ERROR(NEActivationLayer::validate(output, nullptr, activation));
    }

    return Status{};
}

void NEGEMMLowpMatrixMultiplyCore::run()
{
    prepare();

    MemoryGroupResourceScope scope_mg(_memory_group);

    // Convert QASYMM8->QASYMM8_SIGNED
    if(_flip_signedness)
    {
        NEScheduler::get().schedule(&_convert_to_signed_asymm, Window::DimY);
    }

    // Reshape inputs
    if(_mtx_a_reshape_kernel)
    {
        NEScheduler::get().schedule(_mtx_a_reshape_kernel.get(), Window::DimY);
    }
    if(_mtx_b_reshape_kernel && !_reshape_b_only_on_first_run)
    {
        NEScheduler::get().schedule(_mtx_b_reshape_kernel.get(), Window::DimY);
    }

    // Run GEMM
    if(_asm_glue.is_configured())
    {
        _asm_glue.run();
    }
    else
    {
        NEScheduler::get().schedule(_mm_kernel.get(), Window::DimY);
    }

    if(!_fused_assembly_path)
    {
        // Run matrix A reduction kernel only if _b_offset is not equal to 0
        if(_b_offset != 0)
        {
            NEScheduler::get().schedule(&_mtx_a_reduction_kernel, Window::DimX);
        }

        // Run matrix B reduction kernel only if _a_offset is not equal to 0
        if(_a_offset != 0 && !_reshape_b_only_on_first_run)
        {
            NEScheduler::get().schedule(&_mtx_b_reduction_kernel, Window::DimX);
        }

        if(_fuse_output_stage)
        {
            // Run offset contribution kernel
            NEScheduler::get().schedule(&_offset_contribution_output_stage_kernel, Window::DimY);
        }
        else
        {
            // Run offset contribution kernel
            NEScheduler::get().schedule(&_offset_contribution_kernel, Window::DimY);
        }
    }

    // Convert QASYMM8_SIGNED->QASYMM8
    if(_flip_signedness)
    {
        NEScheduler::get().schedule(&_convert_from_signed_asymm, Window::DimY);
    }

    // Run fused activation
    if(_run_activation)
    {
        _activation_func.run();
    }
}

void NEGEMMLowpMatrixMultiplyCore::prepare()
{
    if(!_is_prepared)
    {
        // Run assembly reshape
        if(_asm_glue.is_configured() && _reshape_b_only_on_first_run)
        {
            ARM_COMPUTE_ERROR_ON(!_original_b->is_used());

            _asm_glue.prepare();
            _original_b->mark_as_unused();
        }
        // Run non-assembly reshape
        else if(_mtx_b_reshape_kernel && _reshape_b_only_on_first_run)
        {
            ARM_COMPUTE_ERROR_ON(!_original_b->is_used());

            // Run reshape kernel and mark original weights tensor as unused
            _tmp_b.allocator()->allocate();
            NEScheduler::get().schedule(_mtx_b_reshape_kernel.get(), Window::DimY);
            _original_b->mark_as_unused();
        }

        // Run matrix B reduction kernel only if _a_offset is not equal to 0
        if(_a_offset != 0 && _reshape_b_only_on_first_run)
        {
            _vector_sum_col.allocator()->allocate();
            NEScheduler::get().schedule(&_mtx_b_reduction_kernel, Window::DimX);
        }

        _is_prepared = true;
    }
}