fused_attention_op.cu

/* Copyright (c) 2021 PaddlePaddle Authors. All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License. */

#include <cuda_fp16.h>
#include <cub/cub.cuh>
#include "paddle/fluid/framework/op_registry.h"
#include "paddle/fluid/framework/operator.h"
#include "paddle/fluid/platform/cuda_device_function.h"
#include "paddle/fluid/platform/cudnn_helper.h"

#include "paddle/fluid/operators/elementwise/elementwise_add_op.h"
#include "paddle/fluid/operators/math/math_function.h"

#include "paddle/fluid/operators/fused/attention_layer_norm.h"
#include "paddle/fluid/operators/fused/attn_gemm.h"
#include "paddle/fluid/operators/fused/fmha_ref.h"
#include "paddle/fluid/operators/fused/fused_dropout_helper.h"

namespace paddle {
namespace operators {

using Tensor = framework::Tensor;

template <typename T>
class FusedAttentionOpKernel : public framework::OpKernel<T> {
 public:
  void Compute(const framework::ExecutionContext &ctx) const override {
    using U = LayerNormParamType<T>;
    auto *input_x = ctx.Input<Tensor>("X");

    const auto pre_layer_norm = ctx.Attr<bool>("pre_layer_norm");
    const float epsilon = ctx.Attr<float>("epsilon");
    auto *ln_scale = ctx.Input<Tensor>("LnScale");
    auto *ln_bias = ctx.Input<Tensor>("LnBias");
    auto *ln_mean = ctx.Output<Tensor>("LnMean");
    auto *ln_var = ctx.Output<Tensor>("LnVariance");
    auto *ln_out = ctx.Output<Tensor>("LnOut");

    // x: qkv's input [batch_size, seq_len, dim_embed]
    // y: qkv's weight: [3, num_head, dim_head, dim_embed]
    auto *qkv_weight = ctx.Input<Tensor>("QKVW");
    auto *qkv_bias = ctx.Input<Tensor>("QKVBias");
    auto *qkv_out = ctx.Output<Tensor>("QKVOut");
    auto *qkv_bias_out = ctx.Output<Tensor>("QKVBiasOut");

    auto *src_mask = ctx.Input<Tensor>("SrcMask");
    auto *transpose_out_2 = ctx.Output<Tensor>("TransposeOut2");
    auto *qk_out = ctx.Output<Tensor>("QKOut");
    auto *qktv_out = ctx.Output<Tensor>("QKTVOut");
    auto *softmax_out = ctx.Output<Tensor>("SoftmaxOut");
    auto *attn_dropout_mask_out = ctx.Output<Tensor>("AttnDropoutMaskOut");
    auto *attn_dropout_out = ctx.Output<Tensor>("AttnDropoutOut");
    auto *src_mask_out = ctx.Output<Tensor>("SrcMaskOut");
    auto *fmha_out = ctx.Output<Tensor>("FMHAOut");

    auto *out_linear_weight = ctx.Input<Tensor>("OutLinearW");
    auto *out_linear_bias = ctx.Input<Tensor>("OutLinearBias");
    auto *out_linear_out = ctx.Output<Tensor>("OutLinearOut");

    auto *ln_scale_2 = ctx.Input<Tensor>("Ln2Scale");
    auto *ln_bias_2 = ctx.Input<Tensor>("Ln2Bias");
    auto *dropout_mask_out = ctx.Output<Tensor>("DropoutMaskOut");
    auto *bias_dropout_residual_out =
        ctx.Output<Tensor>("BiasDropoutResidualOut");
    auto *ln_mean_2 = ctx.Output<Tensor>("Ln2Mean");
    auto *ln_var_2 = ctx.Output<Tensor>("Ln2Variance");
    const float ln_epsilon = ctx.Attr<float>("ln_epsilon");

    float attn_dropout_rate = ctx.Attr<float>("attn_dropout_rate");
    bool is_test_1 = ctx.Attr<bool>("attn_dropout_is_test");
    auto &dropout_implementation_1 =
        ctx.Attr<std::string>("attn_dropout_implementation");
    bool is_upscale_in_train_1 =
        (dropout_implementation_1 == "upscale_in_train");
    auto *seed_1 = ctx.HasInput("Seed1") ? ctx.Input<Tensor>("Seed1") : nullptr;
    bool is_fix_seed_1 = ctx.Attr<bool>("attn_dropout_fix_seed");
    int seed_val_1 = ctx.Attr<int>("attn_dropout_seed");

    // final output.
    auto *out = ctx.Output<Tensor>("Y");

    // get data ptr for qkv part.
    const auto input_x_dims = input_x->dims();
    const auto qkv_w_dims = qkv_weight->dims();

    auto *x_data = input_x->data<T>();
    auto *qkv_weight_data = qkv_weight->data<T>();
    auto *qkv_bias_data = (qkv_bias == nullptr) ? nullptr : qkv_bias->data<T>();
    auto *qkv_out_data = qkv_out->mutable_data<T>(ctx.GetPlace());
    auto *qkv_bias_out_data =
        (qkv_bias == nullptr) ? nullptr
                              : qkv_bias_out->mutable_data<T>(ctx.GetPlace());

    // get data ptr for FMHA.
    auto *transpose_out_2_data =
        transpose_out_2->mutable_data<T>(ctx.GetPlace());
    auto *qk_out_data = qk_out->mutable_data<T>(ctx.GetPlace());
    auto *qktv_out_data = qktv_out->mutable_data<T>(ctx.GetPlace());
    auto *src_mask_out_data =
        (src_mask == nullptr) ? nullptr
                              : src_mask_out->mutable_data<T>(ctx.GetPlace());
    auto *softmax_out_data = softmax_out->mutable_data<T>(ctx.GetPlace());
    auto *attn_dropout_mask_out_data =
        attn_dropout_mask_out->mutable_data<uint8_t>(ctx.GetPlace());
    auto *attn_dropout_out_data =
        attn_dropout_out->mutable_data<T>(ctx.GetPlace());
    auto *fmha_out_data = fmha_out->mutable_data<T>(ctx.GetPlace());

    // get data ptr for out_linear.
    auto *out_linear_weight_data = out_linear_weight->data<T>();
    auto *out_linear_bias_data =
        (out_linear_bias == nullptr) ? nullptr : out_linear_bias->data<T>();
    auto *out_linear_out_data = out_linear_out->mutable_data<T>(ctx.GetPlace());

    // get data ptr for bias+dropout+residual+layernorm
    auto *dropout_mask_out_data =
        dropout_mask_out->mutable_data<uint8_t>(ctx.GetPlace());
    auto *final_out_data = out->mutable_data<T>(ctx.GetPlace());

    int batch_size = input_x_dims[0];
    int max_seq_len = input_x_dims[1];
    int dim_embed = input_x_dims[2];

    int num_head = qkv_w_dims[1];
    int dim_head = qkv_w_dims[2];

    int bsz_seq = batch_size * max_seq_len;
    int hidden_size = num_head * dim_head;
    int output_size = 3 * hidden_size;
    int input_size = dim_embed;

    auto layer_norm_compute = AttnLayerNorm<T>(ctx.cuda_device_context(),
                                               epsilon, bsz_seq, dim_embed);

    bool compute_bias = true;
    if (qkv_bias == nullptr) {
      compute_bias = false;
    }
    // (transA, transB, compute_bias) = (false, true, true)
    auto qkv_compute =
        AttnMatMul<T>(ctx.cuda_device_context(), false, true, bsz_seq,
                      output_size, input_size, compute_bias);

    AttnDropoutParam attn_dropout_param(
        is_test_1, dropout_implementation_1, attn_dropout_rate,
        is_upscale_in_train_1, is_fix_seed_1, seed_val_1, seed_1);
    auto fmha_ref_compute =
        FMHARef<T>(ctx.cuda_device_context(), batch_size, max_seq_len, num_head,
                   dim_head, attn_dropout_param);

    output_size = hidden_size;
    // (transA, transB, compute_bias) = (false, false, false)
    auto out_linear_compute =
        AttnMatMul<T>(ctx.cuda_device_context(), false, false, bsz_seq,
                      output_size, input_size, false);
    DropoutParam dropout_param2(ctx, 0);
    FusedDropoutLayerNormHelper<T, uint8_t> fused_dropout_layernorm_helper(
        ctx.cuda_device_context(), bsz_seq, dim_embed, dropout_param2,
        ln_epsilon);

    if (pre_layer_norm) {
      auto *ln_scale_data =
          (ln_scale == nullptr ? nullptr : ln_scale->data<U>());
      auto *ln_bias_data = (ln_bias == nullptr ? nullptr : ln_bias->data<U>());
      auto *ln_mean_data = ln_mean->mutable_data<U>(ctx.GetPlace());
      auto *ln_var_data = ln_var->mutable_data<U>(ctx.GetPlace());
      auto *ln_out_data = ln_out->mutable_data<T>(ctx.GetPlace());

      layer_norm_compute.ComputeForward(x_data, ln_scale_data, ln_bias_data,
                                        ln_out_data, ln_mean_data, ln_var_data);
      qkv_compute.ComputeForward(qkv_weight, ln_out, qkv_bias, qkv_out,
                                 qkv_bias_out);
    } else {
      qkv_compute.ComputeForward(qkv_weight, input_x, qkv_bias, qkv_out,
                                 qkv_bias_out);
    }
    if (qkv_bias == nullptr) {
      fmha_ref_compute.ComputeForward(*qkv_out, src_mask, transpose_out_2,
                                      qk_out, src_mask_out, softmax_out,
                                      attn_dropout_mask_out, attn_dropout_out,
                                      qktv_out, fmha_out);
    } else {
      fmha_ref_compute.ComputeForward(*qkv_bias_out, src_mask, transpose_out_2,
                                      qk_out, src_mask_out, softmax_out,
                                      attn_dropout_mask_out, attn_dropout_out,
                                      qktv_out, fmha_out);
    }

    // fmha_out: [batch_size, seq_len, num_head, head_dim]
    // weight:   [embed_dim, embed_dim]
    // out_linear_out: [batch_size, seq_len, embed_dim]
    out_linear_compute.ComputeForward(out_linear_weight, fmha_out, nullptr,
                                      out_linear_out, nullptr);
    if (pre_layer_norm) {
      // output = (residual + dropout(input + bias))
      fused_dropout_layernorm_helper.ResidualDropoutBias(
          ctx.cuda_device_context(), out_linear_out_data, x_data,
          out_linear_bias_data, final_out_data, dropout_mask_out_data);
    } else {
      auto *ln_scale_2_data =
          (ln_scale_2 == nullptr ? nullptr : ln_scale_2->data<U>());
      auto *ln_bias_2_data =
          (ln_bias_2 == nullptr ? nullptr : ln_bias_2->data<U>());
      auto *bias_dropout_residual_out_data =
          bias_dropout_residual_out->mutable_data<T>(ctx.GetPlace());
      auto *ln_mean_2_data = ln_mean_2->mutable_data<U>(ctx.GetPlace());
      auto *ln_var_2_data = ln_var_2->mutable_data<U>(ctx.GetPlace());
      // output = layernorm(residual + dropout(input + bias))
      fused_dropout_layernorm_helper.LayernormResidualDropoutBias(
          ctx.cuda_device_context(), out_linear_out_data, x_data,
          out_linear_bias_data, ln_scale_2_data, ln_bias_2_data,
          bias_dropout_residual_out_data, dropout_mask_out_data, final_out_data,
          ln_mean_2_data, ln_var_2_data);
    }
  }
};

template <typename T>
class FusedAttentionGradKernel : public framework::OpKernel<T> {
 public:
  void Compute(const framework::ExecutionContext &ctx) const override {
    using U = LayerNormParamType<T>;
    const auto pre_layer_norm = ctx.Attr<bool>("pre_layer_norm");
    const float epsilon = ctx.Attr<float>("epsilon");
    const float ln2epsilon = ctx.Attr<float>("ln_epsilon");

    float attn_dropout_prob = ctx.Attr<float>("attn_dropout_rate");
    bool is_test_1 = ctx.Attr<bool>("attn_dropout_is_test");
    auto &dropout_implementation_1 =
        ctx.Attr<std::string>("attn_dropout_implementation");
    bool is_upscale_in_train_1 =
        (dropout_implementation_1 == "upscale_in_train");
    auto *seed_1 = ctx.HasInput("Seed1") ? ctx.Input<Tensor>("Seed1") : nullptr;
    bool is_fix_seed_1 = ctx.Attr<bool>("attn_dropout_fix_seed");
    int seed_val_1 = ctx.Attr<int>("attn_dropout_seed");

    // get inputs.
    auto *d_y = ctx.Input<Tensor>(framework::GradVarName("Y"));
    auto *d_y_data = d_y->data<T>();

    // fw input
    auto *input_x = ctx.Input<Tensor>("X");
    auto *ln_scale = ctx.Input<Tensor>("LnScale");
    auto *ln_2_scale = ctx.Input<Tensor>("Ln2Scale");
    auto *x_data = input_x->data<T>();
    auto *ln_scale_data = (ln_scale == nullptr ? nullptr : ln_scale->data<U>());
    auto *ln_2_scale_data =
        (ln_2_scale == nullptr ? nullptr : ln_2_scale->data<U>());
    // fw parameters.
    auto *src_mask = ctx.Input<Tensor>("SrcMask");
    auto *qkv_weight = ctx.Input<Tensor>("QKVW");
    auto *qkv_bias = ctx.Input<Tensor>("QKVBias");
    auto *out_linear_weight = ctx.Input<Tensor>("OutLinearW");
    auto *out_linear_bias = ctx.Input<Tensor>("OutLinearBias");
    auto *src_mask_data = (src_mask == nullptr ? nullptr : src_mask->data<T>());
    auto *qkv_weight_data = qkv_weight->data<T>();
    auto *qkv_bias_data = (qkv_bias == nullptr) ? nullptr : qkv_bias->data<T>();
    auto *out_linear_weight_data = out_linear_weight->data<T>();
    auto *out_linear_bias_data =
        (out_linear_bias == nullptr) ? nullptr : out_linear_bias->data<T>();

    // fw output
    auto *fmha_out = ctx.Input<Tensor>("FMHAOut");
    auto *transpose_out_2 = ctx.Input<Tensor>("TransposeOut2");
    auto *qk_out = ctx.Input<Tensor>("QKOut");
    auto *qktv_out = ctx.Input<Tensor>("QKTVOut");
    auto *softmax_out = ctx.Input<Tensor>("SoftmaxOut");
    auto *attn_dropout_mask_out = ctx.Input<Tensor>("AttnDropoutMaskOut");
    auto *attn_dropout_out = ctx.Input<Tensor>("AttnDropoutOut");
    auto *src_mask_out = ctx.Input<Tensor>("SrcMaskOut");
    auto *out_linear_out = ctx.Input<Tensor>("OutLinearOut");
    auto *ln_2_mean = ctx.Input<Tensor>("Ln2Mean");
    auto *ln_2_var = ctx.Input<Tensor>("Ln2Variance");
    auto *dropout_mask_out = ctx.Input<Tensor>("DropoutMaskOut");
    auto *bias_dropout_residual_out =
        ctx.Input<Tensor>("BiasDropoutResidualOut");
    auto *fmha_out_data = fmha_out->data<T>();
    auto *transpose_out_2_data = transpose_out_2->data<T>();
    auto *qk_out_data = qk_out->data<T>();
    auto *qktv_out_data = qktv_out->data<T>();
    auto *softmax_out_data = softmax_out->data<T>();
    auto *src_mask_out_data =
        (src_mask == nullptr) ? nullptr : src_mask_out->data<T>();
    auto *out_linear_out_data = out_linear_out->data<T>();
    auto *dropout_mask_out_data = dropout_mask_out->data<uint8_t>();

    // output's grad
    auto *d_x = ctx.Output<Tensor>(framework::GradVarName("X"));
    auto *d_qkv_out = ctx.Output<Tensor>(framework::GradVarName("QKVOut"));
    auto *d_qkv_bias_out =
        ctx.Output<Tensor>(framework::GradVarName("QKVBiasOut"));
    auto *d_qktv_out = ctx.Output<Tensor>(framework::GradVarName("QKTVOut"));
    auto *d_transpose_out_2 =
        ctx.Output<Tensor>(framework::GradVarName("TransposeOut2"));
    auto *d_qk_out = ctx.Output<Tensor>(framework::GradVarName("QKOut"));
    auto *d_softmax_out =
        ctx.Output<Tensor>(framework::GradVarName("SoftmaxOut"));
    auto *d_attn_dropout_out =
        ctx.Output<Tensor>(framework::GradVarName("AttnDropoutOut"));
    auto *d_src_mask_out =
        ctx.Output<Tensor>(framework::GradVarName("SrcMaskOut"));
    auto *d_fmha_out = ctx.Output<Tensor>(framework::GradVarName("FMHAOut"));
    auto *d_out_linear_out =
        ctx.Output<Tensor>(framework::GradVarName("OutLinearOut"));
    auto *d_bias_dropout_residual_out =
        ctx.Output<Tensor>(framework::GradVarName("BiasDropoutResidualOut"));
    auto *d_x_data = d_x->mutable_data<T>(ctx.GetPlace());
    // when qkv_bias is not nullptr, d_qkv_out is equals to d_qkv_bias_out, the
    // space can be reused.
    auto *d_qkv_out_data = (d_qkv_bias_out != nullptr)
                               ? nullptr
                               : d_qkv_out->mutable_data<T>(ctx.GetPlace());
    auto *d_qkv_bias_out_data =
        (d_qkv_bias_out == nullptr)
            ? nullptr
            : d_qkv_bias_out->mutable_data<T>(ctx.GetPlace());
    auto *d_qktv_out_data = d_qktv_out->mutable_data<T>(ctx.GetPlace());
    auto *d_transpose_out_2_data =
        d_transpose_out_2->mutable_data<T>(ctx.GetPlace());
    auto *d_qk_out_data = d_qk_out->mutable_data<T>(ctx.GetPlace());
    auto *d_softmax_out_data = d_softmax_out->mutable_data<T>(ctx.GetPlace());
    auto *d_attn_dropout_out_data =
        d_attn_dropout_out->mutable_data<T>(ctx.GetPlace());
    auto *d_src_mask_out_data =
        (src_mask == nullptr) ? nullptr
                              : d_src_mask_out->mutable_data<T>(ctx.GetPlace());
    auto *d_fmha_out_data = d_fmha_out->mutable_data<T>(ctx.GetPlace());
    auto *d_out_linear_out_data =
        d_out_linear_out->mutable_data<T>(ctx.GetPlace());

    // parameter grad
    auto *d_qkv_weight = ctx.Output<Tensor>(framework::GradVarName("QKVW"));
    auto *d_qkv_bias = ctx.Output<Tensor>(framework::GradVarName("QKVBias"));
    auto *d_out_linear_weight =
        ctx.Output<Tensor>(framework::GradVarName("OutLinearW"));
    auto *d_out_linear_bias =
        ctx.Output<Tensor>(framework::GradVarName("OutLinearBias"));
    auto *d_ln_2_scale = ctx.Output<Tensor>(framework::GradVarName("Ln2Scale"));
    auto *d_ln_2_bias = ctx.Output<Tensor>(framework::GradVarName("Ln2Bias"));

    auto *d_qkv_weight_data = d_qkv_weight->mutable_data<T>(ctx.GetPlace());
    auto *d_qkv_bias_data = (d_qkv_bias == nullptr)
                                ? nullptr
                                : d_qkv_bias->mutable_data<T>(ctx.GetPlace());
    auto *d_out_linear_weight_data =
        d_out_linear_weight->mutable_data<T>(ctx.GetPlace());
    auto *d_out_linear_bias_data =
        (d_out_linear_bias == nullptr)
            ? nullptr
            : d_out_linear_bias->mutable_data<T>(ctx.GetPlace());

    const auto input_x_dims = input_x->dims();
    const auto qkv_w_dims = qkv_weight->dims();

    int batch_size = input_x_dims[0];
    int max_seq_len = input_x_dims[1];
    int dim_embed = input_x_dims[2];
    int num_head = qkv_w_dims[1];
    int dim_head = qkv_w_dims[2];

    int bsz_seq = batch_size * max_seq_len;
    int hidden_size = num_head * dim_head;
    int output_size = 3 * hidden_size;
    int input_size = dim_embed;

    Tensor d_residual;
    d_residual.Resize(input_x_dims);
    T *d_residual_data = d_residual.mutable_data<T>(ctx.GetPlace());

    bool transA = false;
    bool transB = true;
    bool compute_qkv_bias = true;
    if (qkv_bias == nullptr) {
      compute_qkv_bias = false;
    }
    auto layer_norm_compute = AttnLayerNorm<T>(ctx.cuda_device_context(),
                                               epsilon, bsz_seq, dim_embed);
    auto qkv_compute =
        AttnMatMul<T>(ctx.cuda_device_context(), transA, transB, bsz_seq,
                      output_size, input_size, compute_qkv_bias);
    AttnDropoutParam attn_dropout_param(
        is_test_1, dropout_implementation_1, attn_dropout_prob,
        is_upscale_in_train_1, is_fix_seed_1, seed_val_1, seed_1);
    auto fmha_ref_compute =
        FMHARef<T>(ctx.cuda_device_context(), batch_size, max_seq_len, num_head,
                   dim_head, attn_dropout_param);
    output_size = hidden_size;
    transA = false;
    transB = false;
    bool compute_bias = false;
    auto out_linear_compute =
        AttnMatMul<T>(ctx.cuda_device_context(), transA, transB, bsz_seq,
                      output_size, input_size, compute_bias);
    DropoutParam dropout_param2(ctx, 0);
    FusedDropoutLayerNormHelper<T, uint8_t> fused_dropout_layernorm_helper(
        ctx.cuda_device_context(), bsz_seq, dim_embed, dropout_param2,
        ln2epsilon);

    if (pre_layer_norm) {
      fused_dropout_layernorm_helper.ResidualDropoutBiasGrad(
          ctx.cuda_device_context(), d_y_data, dropout_mask_out_data,
          d_out_linear_out_data, d_residual_data, d_out_linear_bias_data);
    } else {
      auto *ln_2_mean_data = ln_2_mean->data<U>();
      auto *ln_2_var_data = ln_2_var->data<U>();
      auto *bias_dropout_residual_out_data =
          bias_dropout_residual_out->data<T>();
      auto *d_ln_2_scale_data =
          (d_ln_2_scale == nullptr ? nullptr : d_ln_2_scale->mutable_data<U>(
                                                   ctx.GetPlace()));
      auto *d_ln_2_bias_data =
          (d_ln_2_bias == nullptr ? nullptr : d_ln_2_bias->mutable_data<U>(
                                                  ctx.GetPlace()));
      auto *d_bias_dropout_residual_out_data =
          d_bias_dropout_residual_out->mutable_data<T>(ctx.GetPlace());

      fused_dropout_layernorm_helper.LayernormResidualDropoutBiasGrad(
          ctx.cuda_device_context(), d_y_data, bias_dropout_residual_out_data,
          dropout_mask_out_data, ln_2_scale_data, ln_2_mean_data, ln_2_var_data,
          d_bias_dropout_residual_out_data, d_ln_2_scale_data, d_ln_2_bias_data,
          d_out_linear_out_data, d_out_linear_bias_data, d_residual_data);
    }

    out_linear_compute.ComputeBackward(fmha_out, out_linear_weight,
                                       d_out_linear_out, d_fmha_out,
                                       d_out_linear_weight, nullptr);

    if (qkv_bias != nullptr) {
      fmha_ref_compute.ComputeBackward(
          *transpose_out_2, src_mask, *softmax_out, *attn_dropout_mask_out,
          *attn_dropout_out, *qk_out, *src_mask_out, *d_fmha_out, d_qktv_out,
          d_attn_dropout_out, d_softmax_out, d_src_mask_out, d_qk_out,
          d_transpose_out_2, nullptr, d_qkv_bias_out);
    } else {
      fmha_ref_compute.ComputeBackward(
          *transpose_out_2, src_mask, *softmax_out, *attn_dropout_mask_out,
          *attn_dropout_out, *qk_out, *src_mask_out, *d_fmha_out, d_qktv_out,
          d_attn_dropout_out, d_softmax_out, d_src_mask_out, d_qk_out,
          d_transpose_out_2, nullptr, d_qkv_out);
    }

    if (pre_layer_norm) {
      auto *ln_mean = ctx.Input<Tensor>("LnMean");
      auto *ln_var = ctx.Input<Tensor>("LnVariance");
      auto *ln_out = ctx.Input<Tensor>("LnOut");
      auto *ln_mean_data = ln_mean->data<U>();
      auto *ln_var_data = ln_var->data<U>();
      auto *ln_out_data = ln_out->data<T>();

      auto *d_ln_out = ctx.Output<Tensor>(framework::GradVarName("LnOut"));
      auto *d_ln_scale = ctx.Output<Tensor>(framework::GradVarName("LnScale"));
      auto *d_ln_bias = ctx.Output<Tensor>(framework::GradVarName("LnBias"));
      auto *d_ln_out_data = d_ln_out->mutable_data<T>(ctx.GetPlace());
      auto *d_ln_scale_data =
          (d_ln_scale == nullptr ? nullptr
                                 : d_ln_scale->mutable_data<U>(ctx.GetPlace()));
      auto *d_ln_bias_data =
          (d_ln_bias == nullptr ? nullptr
                                : d_ln_bias->mutable_data<U>(ctx.GetPlace()));
      if (qkv_bias != nullptr) {
        qkv_compute.ComputeBackward(ln_out, qkv_weight, d_qkv_bias_out,
                                    d_ln_out, d_qkv_weight, d_qkv_bias);
      } else {
        qkv_compute.ComputeBackward(ln_out, qkv_weight, d_qkv_out, d_ln_out,
                                    d_qkv_weight, d_qkv_bias);
      }
      layer_norm_compute.ComputeBackward(x_data, d_ln_out_data, ln_scale_data,
                                         ln_mean_data, ln_var_data, d_x_data,
                                         d_ln_scale_data, d_ln_bias_data);
    } else {
      if (qkv_bias != nullptr) {
        qkv_compute.ComputeBackward(input_x, qkv_weight, d_qkv_bias_out, d_x,
                                    d_qkv_weight, d_qkv_bias);
      } else {
        qkv_compute.ComputeBackward(input_x, qkv_weight, d_qkv_out, d_x,
                                    d_qkv_weight, d_qkv_bias);
      }
    }
    // gradient accumulation
    std::vector<const Tensor *> ins;
    std::vector<Tensor *> outs;
    ins.emplace_back(&d_residual);
    ins.emplace_back(d_x);
    outs.emplace_back(d_x);
    int elewise_add_axis = -1;
    LaunchElementwiseCudaKernel<ElementwiseType::kBinary, T, T>(
        ctx.cuda_device_context(), ins, &outs, elewise_add_axis,
        AddFunctor<T>());
  }
};

}  // namespace operators
}  // namespace paddle

namespace ops = paddle::operators;
namespace plat = paddle::platform;
REGISTER_OP_CUDA_KERNEL(fused_attention, ops::FusedAttentionOpKernel<float>,
                        ops::FusedAttentionOpKernel<double>,
                        ops::FusedAttentionOpKernel<plat::float16>);
REGISTER_OP_CUDA_KERNEL(fused_attention_grad,
                        ops::FusedAttentionGradKernel<float>,
                        ops::FusedAttentionGradKernel<double>,
                        ops::FusedAttentionGradKernel<plat::float16>);