causal-conv1d/csrc/causal_conv1d_fwd.cu

/******************************************************************************
 * Copyright (c) 2023, Tri Dao.
 ******************************************************************************/

#include <c10/util/BFloat16.h>
#include <c10/util/Half.h>
#include <c10/cuda/CUDAException.h>  // For C10_CUDA_CHECK and C10_CUDA_KERNEL_LAUNCH_CHECK

#include <cub/block/block_load.cuh>
#include <cub/block/block_store.cuh>

#include "causal_conv1d.h"
#include "causal_conv1d_common.h"
#include "static_switch.h"

template<int kNThreads_, int kWidth_, bool kIsVecLoad_, typename input_t_, typename weight_t_>
struct Causal_conv1d_fwd_kernel_traits {
    using input_t = input_t_;
    using weight_t = weight_t_;
    static constexpr int kNThreads = kNThreads_;
    static constexpr int kWidth = kWidth_;
    static constexpr int kNBytes = sizeof(input_t);
    static_assert(kNBytes == 2 || kNBytes == 4);
    static constexpr int kNElts = kNBytes == 4 ? 4 : 8;
    static_assert(kWidth <= kNElts);
    static constexpr bool kIsVecLoad = kIsVecLoad_;
    using vec_t = typename BytesToType<kNBytes * kNElts>::Type;
    using BlockLoadT = cub::BlockLoad<input_t, kNThreads, kNElts, cub::BLOCK_LOAD_WARP_TRANSPOSE>;
    using BlockLoadVecT = cub::BlockLoad<vec_t, kNThreads, 1, cub::BLOCK_LOAD_DIRECT>;
    using BlockStoreT = cub::BlockStore<input_t, kNThreads, kNElts, cub::BLOCK_STORE_WARP_TRANSPOSE>;
    using BlockStoreVecT = cub::BlockStore<vec_t, kNThreads, 1, cub::BLOCK_STORE_DIRECT>;
    static constexpr int kSmemIOSize = kIsVecLoad
        ? 0
        : std::max({sizeof(typename BlockLoadT::TempStorage), sizeof(typename BlockStoreT::TempStorage)});
    static constexpr int kSmemExchangeSize = kNThreads * kNBytes * kNElts;
    static constexpr int kSmemSize = kSmemIOSize + kSmemExchangeSize;
};

template<typename Ktraits>
__global__ __launch_bounds__(Ktraits::kNThreads)
void causal_conv1d_fwd_kernel(ConvParamsBase params) {
    constexpr int kWidth = Ktraits::kWidth;
    constexpr int kNThreads = Ktraits::kNThreads;
    constexpr int kNElts = Ktraits::kNElts;
    constexpr bool kIsVecLoad = Ktraits::kIsVecLoad;
    using input_t = typename Ktraits::input_t;
    using vec_t = typename Ktraits::vec_t;
    using weight_t = typename Ktraits::weight_t;

    // Shared memory.
    extern __shared__ char smem_[];
    auto& smem_load = reinterpret_cast<typename Ktraits::BlockLoadT::TempStorage&>(smem_);
    auto& smem_load_vec = reinterpret_cast<typename Ktraits::BlockLoadVecT::TempStorage&>(smem_);
    auto& smem_store = reinterpret_cast<typename Ktraits::BlockStoreT::TempStorage&>(smem_);
    auto& smem_store_vec = reinterpret_cast<typename Ktraits::BlockStoreVecT::TempStorage&>(smem_);
    vec_t *smem_exchange = reinterpret_cast<vec_t *>(smem_ + Ktraits::kSmemIOSize);

    const int tidx = threadIdx.x;
    const int batch_id = blockIdx.x;
    const int channel_id = blockIdx.y;
    input_t *x = reinterpret_cast<input_t *>(params.x_ptr) + batch_id * params.x_batch_stride
        + channel_id * params.x_c_stride;
    weight_t *weight = reinterpret_cast<weight_t *>(params.weight_ptr) + channel_id * params.weight_c_stride;
    input_t *out = reinterpret_cast<input_t *>(params.out_ptr) + batch_id * params.out_batch_stride
        + channel_id * params.out_c_stride;
    float bias_val = params.bias_ptr == nullptr ? 0.f : float(reinterpret_cast<weight_t *>(params.bias_ptr)[channel_id]);

    // Thread 0 will load the last elements of the previous chunk, so we initialize those to 0.
    if (tidx == 0) {
        input_t zeros[kNElts] = {0};
        smem_exchange[kNThreads - 1] = reinterpret_cast<vec_t *>(zeros)[0];
    }

    float weight_vals[kWidth];
    #pragma unroll
    for (int i = 0; i < kWidth; ++i) { weight_vals[i] = float(weight[i * params.weight_width_stride]); }

    constexpr int kChunkSize = kNThreads * kNElts;
    const int n_chunks = (params.seqlen + kChunkSize - 1) / kChunkSize;
    for (int chunk = 0; chunk < n_chunks; ++chunk) {
        input_t x_vals_load[2 * kNElts] = {0};
        if constexpr(kIsVecLoad) {
            Ktraits::BlockLoadVecT(smem_load_vec).Load(reinterpret_cast<vec_t*>(x), *reinterpret_cast<vec_t (*)[1]>(&x_vals_load[kNElts]), (params.seqlen - chunk * kChunkSize) / kNElts);
        } else {
            __syncthreads();
            Ktraits::BlockLoadT(smem_load).Load(x, *reinterpret_cast<input_t (*)[kNElts]>(&x_vals_load[kNElts]), params.seqlen - chunk * kChunkSize);
        }
        x += kChunkSize;
        __syncthreads();
        // Thread kNThreads - 1 don't write yet, so that thread 0 can read
        // the last elements of the previous chunk.
        if (tidx < kNThreads - 1) { smem_exchange[tidx] = reinterpret_cast<vec_t *>(x_vals_load)[1]; }
        __syncthreads();
        reinterpret_cast<vec_t *>(x_vals_load)[0] = smem_exchange[tidx > 0 ? tidx - 1 : kNThreads - 1];
        __syncthreads();
        // Now thread kNThreads - 1 can write the last elements of the current chunk.
        if (tidx == kNThreads - 1) { smem_exchange[tidx] = reinterpret_cast<vec_t *>(x_vals_load)[1]; }

        float x_vals[2 * kNElts];
        #pragma unroll
        for (int i = 0; i < 2 * kNElts; ++i) { x_vals[i] = float(x_vals_load[i]); }

        float out_vals[kNElts];
        #pragma unroll
        for (int i = 0; i < kNElts; ++i) {
            out_vals[i] = bias_val;
            #pragma unroll
            for (int w = 0; w < kWidth; ++w) {
                out_vals[i] += weight_vals[w] * x_vals[kNElts + i - (kWidth - w - 1)];
            }
        }

        if (params.silu_activation) {
            #pragma unroll
            for (int i = 0; i < kNElts; ++i) {
                out_vals[i] = out_vals[i] / (1 + expf(-out_vals[i]));
            }
        }

        input_t out_vals_store[kNElts];
        #pragma unroll
        for (int i = 0; i < kNElts; ++i) { out_vals_store[i] = out_vals[i]; }
        if constexpr(kIsVecLoad) {
            Ktraits::BlockStoreVecT(smem_store_vec).Store(reinterpret_cast<vec_t*>(out), reinterpret_cast<vec_t (&)[1]>(out_vals_store), (params.seqlen - chunk * kChunkSize) / kNElts);
        } else {
            Ktraits::BlockStoreT(smem_store).Store(out, out_vals_store, params.seqlen - chunk * kChunkSize);
        }
        out += kChunkSize;
    }
}

template<int kNThreads, int kWidth, typename input_t, typename weight_t>
void causal_conv1d_fwd_launch(ConvParamsBase &params, cudaStream_t stream) {
    static constexpr int kNElts = sizeof(input_t) == 4 ? 4 : 8;
    BOOL_SWITCH(params.seqlen % kNElts == 0, kIsVecLoad, [&] {
        using Ktraits = Causal_conv1d_fwd_kernel_traits<kNThreads, kWidth, kIsVecLoad, input_t, weight_t>;
        constexpr int kSmemSize = Ktraits::kSmemSize;
        dim3 grid(params.batch, params.dim);
        auto kernel = &causal_conv1d_fwd_kernel<Ktraits>;
        if (kSmemSize >= 48 * 1024) {
            C10_CUDA_CHECK(cudaFuncSetAttribute(
                kernel, cudaFuncAttributeMaxDynamicSharedMemorySize, kSmemSize));
            }
        kernel<<<grid, Ktraits::kNThreads, kSmemSize, stream>>>(params);
        C10_CUDA_KERNEL_LAUNCH_CHECK();
    });
}

template<typename input_t, typename weight_t>
void causal_conv1d_fwd_cuda(ConvParamsBase &params, cudaStream_t stream) {
    if (params.width == 2) {
        causal_conv1d_fwd_launch<128, 2, input_t, weight_t>(params, stream);
    } else if (params.width == 3) {
        causal_conv1d_fwd_launch<128, 3, input_t, weight_t>(params, stream);
    } else if (params.width == 4) {
        causal_conv1d_fwd_launch<128, 4, input_t, weight_t>(params, stream);
    }
}

template<int kNThreads_, int kWidth_, int kChunkSizeL_, bool kIsVecLoad_, typename input_t_, typename weight_t_>
struct Causal_conv1d_channellast_fwd_kernel_traits {
    // The cache line is 128 bytes, and we try to read 16 bytes per thread.
    // So we have 8 threads per "row", so 32 or 64 elements in the channel dimension.
    // That leaves 4 columns per warp, and so 16 columns per block (assuming each block has 128
    // threads). Each each load is 16 x 32|64 elements in the L x C dimensions.
    using input_t = input_t_;
    using weight_t = weight_t_;
    static constexpr int kNThreads = kNThreads_;
    static_assert(kNThreads % 32 == 0);
    static constexpr int kNWarps = kNThreads / 32;
    static constexpr int kWidth = kWidth_;
    static constexpr int kChunkSizeL = kChunkSizeL_;
    static constexpr int kNBytes = sizeof(input_t);
    static_assert(kNBytes == 2 || kNBytes == 4);
    static constexpr int kNElts = kNBytes == 4 ? 4 : 8;
    static constexpr int kNEltsPerRow = 128 / kNBytes;
    static constexpr int kNThreadsPerRow = kNEltsPerRow / kNElts;  // Always 8 for now
    static_assert(kNThreadsPerRow * kNBytes * kNElts == 128);
    static constexpr int kNColsPerWarp = 32 / kNThreadsPerRow;  // Always 4 for now
    static_assert(kNColsPerWarp * kNThreadsPerRow == 32);
    static constexpr int kNColsPerLoad = kNColsPerWarp * kNWarps;
    static constexpr int kNLoads = kChunkSizeL / kNColsPerLoad;
    static_assert(kNLoads * kNColsPerLoad == kChunkSizeL);
    static constexpr bool kIsVecLoad = kIsVecLoad_;
    using vec_t = typename BytesToType<kNBytes * kNElts>::Type;
    // using BlockLoadT = cub::BlockLoad<input_t, kNThreads, kNItems, cub::BLOCK_LOAD_WARP_TRANSPOSE>;
    // using BlockStoreT = cub::BlockStore<input_t, kNThreads, kNItems, cub::BLOCK_STORE_WARP_TRANSPOSE>;
    // static constexpr int kSmemSize = std::max({sizeof(typename BlockLoadT::TempStorage),
    //                                            sizeof(typename BlockStoreT::TempStorage)});
    // static constexpr int kSmemSize = kChunkSizeL * kNEltsPerRow * kNBytes;
};

template<typename Ktraits>
__global__ __launch_bounds__(Ktraits::kNThreads)
void causal_conv1d_channellast_fwd_kernel(ConvParamsBase params) {
    constexpr int kWidth = Ktraits::kWidth;
    constexpr int kNThreads = Ktraits::kNThreads;
    constexpr int kNElts = Ktraits::kNElts;
    constexpr int kNWarp = Ktraits::kNWarps;
    constexpr int kNThreadsPerC = Ktraits::kNThreadsPerRow;
    constexpr int kLPerLoad = Ktraits::kNColsPerLoad;
    constexpr int kChunkSizeL = Ktraits::kChunkSizeL;
    constexpr int kChunkSizeC = Ktraits::kNEltsPerRow;
    using input_t = typename Ktraits::input_t;
    using vec_t = typename Ktraits::vec_t;
    using weight_t = typename Ktraits::weight_t;

    // Shared memory.
    __shared__ input_t x_smem[kWidth - 1 + kChunkSizeL][kChunkSizeC + kNElts];

    const int tid = threadIdx.x;
    const int l_idx = tid / kNThreadsPerC;
    const int c_idx = tid % kNThreadsPerC;
    const int batch_id = blockIdx.x;
    const int chunk_l_id = blockIdx.y;
    const int chunk_c_id = blockIdx.z;
    input_t *x = reinterpret_cast<input_t *>(params.x_ptr) + batch_id * params.x_batch_stride
        + (chunk_l_id * kChunkSizeL + l_idx) * params.x_l_stride + chunk_c_id * kChunkSizeC + c_idx * kNElts;
    weight_t *weight = reinterpret_cast<weight_t *>(params.weight_ptr)
        + chunk_c_id * kChunkSizeC * params.weight_c_stride;
    input_t *out = reinterpret_cast<input_t *>(params.out_ptr) + batch_id * params.out_batch_stride
        + (chunk_l_id * kChunkSizeL + l_idx) * params.out_l_stride + chunk_c_id * kChunkSizeC + c_idx * kNElts;

    #pragma unroll
    for (int l = 0; l < Ktraits::kNLoads; ++l) {
        input_t x_vals_load[kNElts] = {0};
        if (chunk_l_id * kChunkSizeL + l * kLPerLoad + l_idx < params.seqlen
            && chunk_c_id * kChunkSizeC + c_idx * kNElts < params.dim) {
            reinterpret_cast<vec_t *>(x_vals_load)[0] = *reinterpret_cast<vec_t *>(x + l * kLPerLoad * params.x_l_stride);
        }
        reinterpret_cast<vec_t *>(x_smem[kWidth - 1 + l * kLPerLoad + l_idx])[c_idx] = reinterpret_cast<vec_t *>(x_vals_load)[0];
    }
    // Load the elements from the previous chunk that are needed for convolution.
    if (l_idx < kWidth - 1) {
        input_t x_vals_load[kNElts] = {0};
        if (chunk_l_id * kChunkSizeL + l_idx - (kWidth - 1) >= 0
            && chunk_l_id * kChunkSizeL + l_idx - (kWidth - 1) < params.seqlen
            && chunk_c_id * kChunkSizeC + c_idx * kNElts < params.dim) {
            reinterpret_cast<vec_t *>(x_vals_load)[0] = *reinterpret_cast<vec_t *>(x - (kWidth - 1) * params.x_l_stride);
        }
        reinterpret_cast<vec_t *>(x_smem[l_idx])[c_idx] = reinterpret_cast<vec_t *>(x_vals_load)[0];
    }

    __syncthreads();

    constexpr int kLPerThread = std::min(kChunkSizeL * kChunkSizeC / kNThreads, kChunkSizeL);
    static_assert(kLPerThread * kNThreads == kChunkSizeL * kChunkSizeC);
    constexpr int kNThreadsPerRow = kChunkSizeL / kLPerThread;
    static_assert(kNThreadsPerRow * kLPerThread == kChunkSizeL);
    // kChunkSizeL, kLPerThread, kNThreadsPerRow should be powers of 2 for simplicity
    static_assert((kChunkSizeL & (kChunkSizeL - 1)) == 0);
    static_assert((kLPerThread & (kLPerThread - 1)) == 0);
    static_assert((kNThreadsPerRow & (kNThreadsPerRow - 1)) == 0);
    static_assert(kNThreadsPerRow <= 32);

    const int row_idx = tid / kNThreadsPerRow;
    const int col_idx = tid % kNThreadsPerRow;

    float bias_val = params.bias_ptr == nullptr || chunk_c_id * kChunkSizeC + row_idx >= params.dim ? 0.f : float(reinterpret_cast<weight_t *>(params.bias_ptr)[chunk_c_id * kChunkSizeC + row_idx]);
    float weight_vals[kWidth] = {0};
    if (chunk_c_id + kChunkSizeC + row_idx < params.dim) {
        #pragma unroll
        for (int w = 0; w < kWidth; ++w) {
            weight_vals[w] = weight[row_idx * params.weight_c_stride + w * params.weight_width_stride];
        }
    }
    float x_vals[kWidth - 1 + kLPerThread];
    #pragma unroll
    for (int i = 0; i < kWidth - 1 + kLPerThread; ++i) {
        x_vals[i] = float(x_smem[col_idx * kLPerThread + i][row_idx]);
    }

    float out_vals[kLPerThread];
    #pragma unroll
    for (int i = 0; i < kLPerThread; ++i) {
        out_vals[i] = bias_val;
        #pragma unroll
        for (int w = 0; w < kWidth; ++w) { out_vals[i] += weight_vals[w] * x_vals[i + w]; }
        if (params.silu_activation) {out_vals[i] = out_vals[i] / (1 + expf(-out_vals[i])); }
    }

    // Since kNThreadsPerRow is a power of 2 and <= 32, we only need syncwarp and not syncthreads.
    __syncwarp();
    #pragma unroll
    for (int i = 0; i < kLPerThread; ++i) { x_smem[col_idx * kLPerThread + i][row_idx] = out_vals[i]; }
    __syncthreads();

    #pragma unroll
    for (int l = 0; l < Ktraits::kNLoads; ++l) {
        input_t out_vals_store[kNElts];
        reinterpret_cast<vec_t *>(out_vals_store)[0] = reinterpret_cast<vec_t *>(x_smem[l * kLPerLoad + l_idx])[c_idx];
        if (chunk_l_id * kChunkSizeL + l * kLPerLoad + l_idx < params.seqlen
            && chunk_c_id * kChunkSizeC + c_idx * kNElts < params.dim) {
            *reinterpret_cast<vec_t *>(out + l * kLPerLoad * params.out_l_stride) = reinterpret_cast<vec_t *>(out_vals_store)[0];
        }
    }

}

template<int kNThreads, int kWidth, typename input_t, typename weight_t>
void causal_conv1d_channellast_fwd_launch(ConvParamsBase &params, cudaStream_t stream) {
    using Ktraits = Causal_conv1d_channellast_fwd_kernel_traits<kNThreads, kWidth, 64, true, input_t, weight_t>;
    // constexpr int kSmemSize = Ktraits::kSmemSize;
    constexpr int kChunkSizeL = Ktraits::kChunkSizeL;
    constexpr int kChunkSizeC = Ktraits::kNEltsPerRow;
    const int n_chunks_L = (params.seqlen + kChunkSizeL - 1) / kChunkSizeL;
    const int n_chunks_C = (params.dim + kChunkSizeC - 1) / kChunkSizeC;
    // printf("n_chunks_L: %d, n_chunks_C: %d\n", n_chunks_L, n_chunks_C);
    dim3 grid(params.batch, n_chunks_L, n_chunks_C);
    dim3 block(Ktraits::kNThreads);
    auto kernel = &causal_conv1d_channellast_fwd_kernel<Ktraits>;
    // if (kSmemSize >= 48 * 1024) {
    //     C10_CUDA_CHECK(cudaFuncSetAttribute(
    //         kernel, cudaFuncAttributeMaxDynamicSharedMemorySize, kSmemSize));
    //     }
    // kernel<<<grid, Ktraits::kNThreads, kSmemSize, stream>>>(params);
    kernel<<<grid, Ktraits::kNThreads, 0, stream>>>(params);
    C10_CUDA_KERNEL_LAUNCH_CHECK();
}

template<typename input_t, typename weight_t>
void causal_conv1d_channellast_fwd_cuda(ConvParamsBase &params, cudaStream_t stream) {
    if (params.width == 2) {
        causal_conv1d_channellast_fwd_launch<128, 2, input_t, weight_t>(params, stream);
    } else if (params.width == 3) {
        causal_conv1d_channellast_fwd_launch<128, 3, input_t, weight_t>(params, stream);
    } else if (params.width == 4) {
        causal_conv1d_channellast_fwd_launch<128, 4, input_t, weight_t>(params, stream);
    }
}

template void causal_conv1d_fwd_cuda<float, float>(ConvParamsBase &params, cudaStream_t stream);
template void causal_conv1d_fwd_cuda<at::Half, float>(ConvParamsBase &params, cudaStream_t stream);
template void causal_conv1d_fwd_cuda<at::BFloat16, float>(ConvParamsBase &params, cudaStream_t stream);
template void causal_conv1d_fwd_cuda<float, at::Half>(ConvParamsBase &params, cudaStream_t stream);
template void causal_conv1d_fwd_cuda<at::Half, at::Half>(ConvParamsBase &params, cudaStream_t stream);
template void causal_conv1d_fwd_cuda<at::BFloat16, at::Half>(ConvParamsBase &params, cudaStream_t stream);
template void causal_conv1d_fwd_cuda<float, at::BFloat16>(ConvParamsBase &params, cudaStream_t stream);
template void causal_conv1d_fwd_cuda<at::Half, at::BFloat16>(ConvParamsBase &params, cudaStream_t stream);
template void causal_conv1d_fwd_cuda<at::BFloat16, at::BFloat16>(ConvParamsBase &params, cudaStream_t stream);

template void causal_conv1d_channellast_fwd_cuda<float, float>(ConvParamsBase &params, cudaStream_t stream);
template void causal_conv1d_channellast_fwd_cuda<at::Half, float>(ConvParamsBase &params, cudaStream_t stream);
template void causal_conv1d_channellast_fwd_cuda<at::BFloat16, float>(ConvParamsBase &params, cudaStream_t stream);
template void causal_conv1d_channellast_fwd_cuda<float, at::Half>(ConvParamsBase &params, cudaStream_t stream);
template void causal_conv1d_channellast_fwd_cuda<at::Half, at::Half>(ConvParamsBase &params, cudaStream_t stream);
template void causal_conv1d_channellast_fwd_cuda<at::BFloat16, at::Half>(ConvParamsBase &params, cudaStream_t stream);
template void causal_conv1d_channellast_fwd_cuda<float, at::BFloat16>(ConvParamsBase &params, cudaStream_t stream);
template void causal_conv1d_channellast_fwd_cuda<at::Half, at::BFloat16>(ConvParamsBase &params, cudaStream_t stream);
template void causal_conv1d_channellast_fwd_cuda<at::BFloat16, at::BFloat16>(ConvParamsBase &params, cudaStream_t stream);