text: /*******************************************************************************
  * Copyright 2019-2020 Intel Corporation
  *
  * 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 <stdlib.h>
  
  #include "tests/test_thread.hpp"
  
  #include "rnn/rnn.hpp"
  #include "rnn/rnn_aux.hpp"
  
  #include "rnn/cells.hpp"
  
  namespace rnn {
  template <typename T1, typename T2>
  void lbr_gru_fwd_postgemm_template(T1 func1, T2 func2, const prb_t &prb,
          float *gates_, const float *src_iter_, const float *bias_,
          float *dst_layer_, float *cell_scratchpad_) {
      AOC<const float> src_iter(src_iter_, prb.mb, prb.wc);
      AOC<const float> bias(bias_, prb.n_gates() + 1, prb.dhc);
      AOC<float> gates(gates_, prb.mb, prb.n_gates(), prb.dhc);
      AOC<float> dst_layer(dst_layer_, prb.mb, prb.wc);
      AOC<float> cell_scratchpad(
              cell_scratchpad_, prb.mb, prb.n_gates(), prb.dhc);
  
      for (int64_t i = 0; i < prb.mb; i++)
          for (int64_t j = 0; j < prb.n_gates() - 1; j++)
              for (int64_t k = 0; k < prb.dhc; k++) {
                  gates(i, j, k) = func1(prb.linear_scales[j],
                          gates(i, j, k) + cell_scratchpad(i, j, k) + bias(j, k));
              }
  
      for (int64_t i = 0; i < prb.mb; i++)
          for (int64_t k = 0; k < prb.dhc; k++) {
              gates(i, GRU_O, k) = func2(prb.linear_scales[GRU_O],
                      gates(i, GRU_O, k)
                              + gates(i, GRU_R, k)
                                      * (cell_scratchpad(i, GRU_O, k)
                                              + bias(LBR_GRU_U_PRIME, k))
                              + bias(GRU_O, k));
          }
  
      for (int64_t i = 0; i < prb.mb; i++)
          for (int64_t k = 0; k < prb.dhc; k++) {
              dst_layer(i, k) = gates(i, GRU_U, k) * src_iter(i, k)
                      + (1 - gates(i, GRU_U, k)) * gates(i, GRU_O, k);
          }
  }
  
  void lbr_gru_fwd_postgemm(const prb_t &prb, float *gates_,
          const float *src_iter_, const float *bias_, float *dst_layer_,
          float *cell_scratchpad_) {
      if (prb.skip_nonlinear)
          lbr_gru_fwd_postgemm_template(
                  [](float scale, float a) { return scale * a; },
                  [](float scale, float a) { return scale * a; }, prb, gates_,
                  src_iter_, bias_, dst_layer_, cell_scratchpad_);
      else
          lbr_gru_fwd_postgemm_template(
                  [](float scale, float a) { return logistic(a); },
                  [](float scale, float a) { return tanhf(a); }, prb, gates_,
                  src_iter_, bias_, dst_layer_, cell_scratchpad_);
  }
  
  void lbr_gru_fwd(const prb_t &prb, float *dst_layer_, float *gates_,
          const float *weights_layer_, const float *weights_iter_,
          const float *bias_, const float *src_layer_, const float *src_iter_,
          float *cell_scratchpad_) {
      gemm("C", "N", "N", prb.mb, prb.n_gates() * prb.dhc, prb.slc, 1.0,
              src_layer_, prb.wc, weights_layer_, prb.n_gates() * prb.dhc, 0.0,
              gates_, prb.n_gates() * prb.dhc);
  
      gemm("C", "N", "N", prb.mb, prb.n_gates() * prb.dhc, prb.sic, 1.0,
              src_iter_, prb.wc, weights_iter_, prb.n_gates() * prb.dhc, 0.0,
              cell_scratchpad_, prb.n_gates() * prb.dhc);
  
      lbr_gru_fwd_postgemm(
              prb, gates_, src_iter_, bias_, dst_layer_, cell_scratchpad_);
  }
  
  void lbr_gru_bwd_pregemm(const prb_t &prb, const float *src_iter_,
          const float *diff_dst_layer_, const float *diff_dst_iter_,
          const float *gates_, const float *Wh_b_, float *diff_src_iter_,
          float *b_gates_, float *b_gates_r_) {
      AOC<const float> src_iter(src_iter_, prb.mb, prb.wc);
      AOC<const float> diff_dst_layer(diff_dst_layer_, prb.mb, prb.wc);
      AOC<const float> diff_dst_iter(diff_dst_iter_, prb.mb, prb.wc);
      AOC<const float> gates(gates_, prb.mb, prb.n_gates(), prb.dhc);
      AOC<const float> Wh_b(Wh_b_, prb.mb, prb.dhc);
  
      AOC<float> diff_src_iter(diff_src_iter_, prb.mb, prb.wc);
      AOC<float> b_gates(b_gates_, prb.mb, prb.n_gates(), prb.dhc);
      AOC<float> b_gates_r(b_gates_r_, prb.mb, prb.n_gates(), prb.dhc);
  
      // do = (1 - u) * dh; do^ = one_m_square(o) * do;
      // du = (h - o) * dh; du^ = x_m_square(u) * du;
      // dr = (Wh + b) * do^; dr^ = x_m_square(r) * dr;
      for (int64_t ib = 0; ib < prb.mb; ib++)
          for (int64_t ih = 0; ih < prb.dhc; ih++) {
              float h = src_iter(ib, ih);
              float dh = diff_dst_layer(ib, ih) + diff_dst_iter(ib, ih);
              float u = gates(ib, GRU_U, ih);
              float r = gates(ib, GRU_R, ih);
              float o = gates(ib, GRU_O, ih);
              float du = (h - o) * dh;
              float dO = (1.0f - u) * dh;
  
              b_gates(ib, GRU_U, ih) = x_m_square(u) * du;
              b_gates(ib, GRU_O, ih) = one_m_square(o) * dO;
  
              float dr = Wh_b(ib, ih) * b_gates(ib, GRU_O, ih);
              b_gates(ib, GRU_R, ih) = x_m_square(r) * dr;
  
              b_gates_r(ib, GRU_U, ih) = b_gates(ib, GRU_U, ih);
              b_gates_r(ib, GRU_R, ih) = b_gates(ib, GRU_R, ih);
              b_gates_r(ib, GRU_O, ih) = b_gates(ib, GRU_O, ih) * r;
              diff_src_iter(ib, ih) = dh * u;
          }
  }
  
  void lbr_gru_bwd(const prb_t &prb, float *diff_src_layer_,
          float *diff_src_iter_, float *diff_weights_layer_,
          float *diff_weights_iter_, float *diff_bias_, float *b_gates_,
          const float *src_layer_, const float *src_iter_,
          const float *weights_layer_, const float *weights_iter_,
          const float *bias_, const float *gates_, const float *diff_dst_layer_,
          const float *diff_dst_iter_, float *cell_scratchpad_) {
      AOC<const float> weights_iter(
              weights_iter_, prb.sic, prb.n_gates(), prb.dhc);
      AOC<const float> bias(bias_, prb.n_gates() + 1, prb.dhc);
  
      float *Wh_b_ = cell_scratchpad_;
      float *b_gates_r_ = cell_scratchpad_ + prb.dhc * prb.mb;
      AOC<float> Wh_b(Wh_b_, prb.mb, prb.dhc);
      AOC<float> b_gates_r(b_gates_r_, prb.mb, prb.n_gates(), prb.dhc);
  
      // TODO: save this this GEMM + bias in the fwd pass
      for (int64_t ib = 0; ib < prb.mb; ib++)
          for (int64_t ih = 0; ih < prb.dhc; ih++)
              Wh_b(ib, ih) = bias(LBR_GRU_U_PRIME, ih);
  
      gemm("C", "N", "N", prb.mb, prb.dhc, prb.sic, 1.0, src_iter_, prb.wc,
              &weights_iter(0, GRU_O, 0), prb.n_gates() * prb.dhc, 1.0, Wh_b_,
              prb.dhc);
  
      lbr_gru_bwd_pregemm(prb, src_iter_, diff_dst_layer_, diff_dst_iter_, gates_,
              Wh_b_, diff_src_iter_, b_gates_, b_gates_r_);
  
      gemm("C", "T", "N", prb.sic, prb.n_gates() * prb.dhc, prb.mb, 1.0,
              src_iter_, prb.wc, b_gates_r_, prb.n_gates() * prb.dhc, 1.0,
              diff_weights_iter_, prb.n_gates() * prb.dhc);
      gemm("C", "T", "N", prb.slc, prb.n_gates() * prb.dhc, prb.mb, 1.0,
              src_layer_, prb.wc, b_gates_, prb.n_gates() * prb.dhc, 1.0,
              diff_weights_layer_, prb.n_gates() * prb.dhc);
  
      gemm("C", "N", "T", prb.mb, prb.slc, prb.n_gates() * prb.dhc, 1.0, b_gates_,
              prb.n_gates() * prb.dhc, weights_layer_, prb.n_gates() * prb.dhc,
              0.0, diff_src_layer_, prb.wc);
      gemm("C", "N", "T", prb.mb, prb.sic, prb.n_gates() * prb.dhc, 1.0,
              b_gates_r_, prb.n_gates() * prb.dhc, weights_iter_,
              prb.n_gates() * prb.dhc, 1.0, diff_src_iter_, prb.wc);
  
      gates_reduction(prb, b_gates_, diff_bias_);
      for (int64_t i = 0; i < prb.mb; i++)
          for (int64_t k = 0; k < prb.dhc; k++)
              diff_bias_[LBR_GRU_U_PRIME * prb.dhc + k] += b_gates_r(i, GRU_O, k);
  }
  
  } // namespace rnn
  