SparseConvTransposeSYCL.h

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// ----------------------------------------------------------------------------
// -                        Open3D: www.open3d.org                            -
// ----------------------------------------------------------------------------
// Copyright (c) 2018-2026 www.open3d.org
// SPDX-License-Identifier: MIT
// ----------------------------------------------------------------------------
 
// SYCL port of SparseConvTranspose.cuh. See SparseConvSYCL.h's file header
// for general porting notes. Uses <ColumnMajor, ColumnMajor> GEMM (same as
// forward SparseConv) and the shared MultiplyColumnsSYCL kernel for the
// optional out_importance scaling.
#pragma once
 
#include "open3d/ml/impl/GemmSYCL.h"
#include "open3d/ml/impl/continuous_conv/ContinuousConvSYCLKernels.h"
#include "open3d/ml/impl/misc/MemoryAllocation.h"
#include "open3d/ml/impl/sparse_conv/SparseConvSYCLKernels.h"
#include "open3d/utility/Helper.h"
 
using open3d::utility::DivUp;
 
namespace open3d {
namespace ml {
namespace impl {
 
template <class TFeat, class TOut, class TIndex, class TKernelIndex>
void SparseConvTransposeComputeFeaturesSYCL(
        sycl::queue& queue,
        void* temp,
        size_t& temp_size,
        size_t& max_temp_size,
        int texture_alignment,
        TOut* out_features,
        const std::vector<int>& filter_dims,
        const TFeat* filter,
        TIndex num_out,
        const TFeat* out_importance,
        TIndex num_inp,
        const TFeat* inp_features,
        const TFeat* inp_neighbors_importance_sum,
        const int64_t* inp_neighbors_prefix_sum,
        size_t neighbors_index_size,
        const TIndex* neighbors_index,
        const TKernelIndex* neighbors_kernel_index,
        const TFeat* neighbors_importance,
        const int64_t* neighbors_row_splits,
        bool normalize,
        bool allow_tf32) {
    const bool get_temp_size = !temp;
 
    if (get_temp_size) {
        temp = (char*)1;
        temp_size = std::numeric_limits<int64_t>::max();
    }
 
    MemoryAllocation mem_temp(temp, temp_size, texture_alignment);
 
    const int in_channels = filter_dims[filter_dims.size() - 2];
    const int out_channels = filter_dims[filter_dims.size() - 1];
 
    int num_kernel_elements = 1;
    for (size_t i = 0; i < filter_dims.size() - 2; ++i)
        num_kernel_elements *= filter_dims[i];
 
    const size_t min_num_cols_per_run = std::min(size_t(num_out), size_t(32));
    const size_t max_num_cols_per_run = num_out;
    const size_t bytes_per_column =
            sizeof(TFeat) * (num_kernel_elements * in_channels);
    const size_t min_temp_size_bytes = min_num_cols_per_run * bytes_per_column;
    const size_t max_temp_size_bytes = max_num_cols_per_run * bytes_per_column;
 
    if (get_temp_size) {
        std::pair<char*, size_t> tmp =
                mem_temp.Alloc<char>(min_temp_size_bytes);
        temp_size = mem_temp.MaxUsed();
        mem_temp.Free(tmp);
        mem_temp.Alloc<char>(max_temp_size_bytes);
        max_temp_size = mem_temp.MaxUsed();
        return;
    }
 
    std::pair<void*, size_t> mem_columns = mem_temp.AllocLargestSegment();
 
    if (mem_columns.second < min_temp_size_bytes) {
        std::stringstream ss;
        ss << "temp is too small " << mem_columns.second
           << " bytes. Expected at least " << min_temp_size_bytes << " bytes\n";
        throw std::runtime_error(ss.str());
    }
 
    sycl::event out_features_fill_event =
            queue.fill(out_features, TOut(0), size_t(num_out) * out_channels);
 
    size_t num_cols_per_run =
            std::min(mem_columns.second / bytes_per_column, size_t(num_out));
 
    TFeat* columns = (TFeat*)mem_columns.first;
 
    size_t num_runs = DivUp(num_out, num_cols_per_run);
    // See SparseConvSYCL.h for the event-dependency reasoning: each chunk's
    // GEMM depends on that chunk's FillColumnTranspose event (via
    // GemmColumnMajorSYCL's internal barrier); GemmColumnMajorSYCL does not
    // block, so the NEXT chunk's FillColumnTranspose -- which reuses the
    // same `columns` scratch buffer -- must explicitly depend on the
    // previous chunk's GEMM event.
    sycl::event prev_gemm_event;
    for (size_t run_i = 0; run_i < num_runs; ++run_i) {
        const TIndex begin_idx = TIndex(run_i * num_cols_per_run);
        const TIndex end_idx = TIndex(
                std::min(size_t(num_out), (run_i + 1) * num_cols_per_run));
        const size_t num_cols_this_run = end_idx - begin_idx;
 
        sycl::event fill_column_event = FillColumnTransposeSYCL<TFeat, TIndex,
                                                                TKernelIndex>(
                queue, columns, in_channels, begin_idx, end_idx, num_out,
                num_inp, inp_features, inp_neighbors_importance_sum,
                inp_neighbors_prefix_sum, neighbors_index_size, neighbors_index,
                neighbors_kernel_index, neighbors_importance,
                neighbors_row_splits, num_kernel_elements, normalize,
                run_i == 0 ? std::vector<sycl::event>{out_features_fill_event}
                           : std::vector<sycl::event>{prev_gemm_event});
 
        // C(MxN) = A(MxK) * B(KxN); A=filter, B=columns, C=out_features
        // (all column-major).
        const int m = out_channels;
        const int k = num_kernel_elements * in_channels;
        const int n = static_cast<int>(num_cols_this_run);
        const float alpha = 1;
        const float* const A = filter;
        const int lda = m;
        const float* const B = columns;
        const int ldb = k;
        const float beta = 1;
        float* C = out_features + run_i * num_cols_per_run * out_channels;
        const int ldc = m;
 
        prev_gemm_event = GemmColumnMajorSYCL<cutlass::layout::ColumnMajor,
                                              cutlass::layout::ColumnMajor>(
                queue, m, n, k, alpha, A, lda, B, ldb, beta, C, ldc, allow_tf32,
                {fill_column_event});
    }
 
    if (out_importance) {
        // Must depend on the last chunk's GEMM: GemmColumnMajorSYCL no
        // longer blocks (see GemmSYCL.h), and this in-place scale reads/
        // writes the same out_features region that GEMM just wrote.
        MultiplyColumnsSYCL(queue, out_channels, num_out, out_features,
                            out_importance, {prev_gemm_event});
    }
}
 
}  // namespace impl
}  // namespace ml
}  // namespace open3d