# Copyright (c) 2018 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. import numpy as np import os import shutil from . import core class InferenceTranspiler: def transpile(self, program, scope, place): ''' Transpile the program to a inference program by fused batch normalization. The batch normalization followed the convolution or fully connected layer can be integrated with them. Doing so will give us a forward acceleration, especially in environments like mobile or embedded. For input X: - Conv process: X = input * W + bias - Batch norm process: X' = (X - mean) / std - Scale Process: Y = a * X' + b After fuse into one operation: Y = (input * W + bias - mean) / std * a + b = input * a * W / std + ((bias - mean) / std * a + b) The operator transformation is: - before: - conv->batch_norm->any_other_op (bias == 0) - conv->elementwise_add->batch_norm->any_other_op (bias != 0) - after: - conv->elementwise_add->any_other_op The transpile stages are: 1. insert elementwise_add op when bias == 0, and adjust its input and output. 2. fuse the batch_norm's parameters to conv and elementwise_add operators. 3. remove batch_norm ops and its variables which are not used in any other ops. 4. remove unused variables. :param program: program to transpile :type program: Program :param scope: inference scope :type scope: Scope :param place: inference place :type place: Place :return: program by fused batch normalization :rtype: Program ''' self.scope = scope self.place = place self.block = program.block(0) i = 0 while i < len(self.block.ops): current_op = self.block.ops[i] # TODO(luotao1): consider only conv2d now. fc would be delt later. if current_op.type in ['conv2d']: next_op = self.block.ops[i + 1] # TODO(luotao1): consider only conv2d without bias now. # If conv2d with bias, the next_op.type is elementwise_add. if (next_op.type == 'batch_norm'): # insert bias op bias_op = self._insert_bias_op(i + 1, current_op, next_op) # fuse batch_norm self._fuse_param(current_op, next_op, bias_op) # remove batch_norm_op self.block.remove_op(i + 2) i = i + 1 i = i + 1 self._remove_unused_var() return program # ====================== private transpiler functions ===================== def _insert_bias_op(self, index, current_op, bn_op): ''' Construct elementwise_add operator for adding bias and insert it into program. :param index: insert location of bias_op :type index: Int :param current_op: current operator (conv or fc) :type current_op: Operator :param bn_op: batch norm operator :type bn_op: Operator :return: bias_op :rtype: Operator ''' # The input of bias_op is current_op's output and Bias of bn_op # The output of bias_op is bn_op's output x_var = self.block.var(current_op.output("Output")[0]) y_var = self.block.var(bn_op.input("Bias")[0]) out_var = self.block.var(bn_op.output("Y")[0]) bias_op = self.block.insert_op( index, type="elementwise_add", inputs={"X": x_var, "Y": y_var}, outputs={"Out": out_var}, attrs={"axis": 1}) # dim_start=1 return bias_op def _fuse_param(self, current_op, bn_op, bias_op): ''' fuse the batch_norm_op' parameters to current_op (conv or fc) :param current_op: current operator (conv or fc) :type current_op: Operator :param bn_op: batch norm operator :type bn_op: Operator :param bias_op: elementwise_add operator for adding bias :type bias_op: Operator ''' def _load_tensor(param_name): return self.scope.find_var(param_name[0]).get_tensor() def _load_param(param_name): return np.array(_load_tensor(param_name)) bias_bn = _load_param(bn_op.input("Bias")) #Bias scale_bn = _load_param(bn_op.input("Scale")) #Scale mean_bn = _load_param(bn_op.input("Mean")) #Mean var_bn = _load_param(bn_op.input("Variance")) #Variance # TODO(luotao1): consider only conv2d now. fc would be delt later. current_param = _load_param(current_op.input("Filter")) current_tensor = _load_tensor(current_op.input("Filter")) std_bn = np.float32(np.sqrt(np.add(var_bn, 1e-5))) tmp = np.float32(np.divide(scale_bn, std_bn)) # add bias of batch_norm_op to conv2d bias = np.zeros(bias_bn.shape) bias = np.float32( np.add(np.multiply(np.subtract(bias, mean_bn), tmp), bias_bn)) bias_tensor = _load_tensor(bias_op.input("Y")) bias_tensor.set(bias, self.place) # re-compute weight of conv2d tmp = tmp.reshape(tmp.shape[0], -1) dst_param = current_param.reshape((tmp.shape[0], -1)) dst_param = np.float32(np.multiply(dst_param, tmp)) dst_param = dst_param.reshape(current_param.shape) # set the updated parameters current_tensor.set(np.array(dst_param), self.place) def _remove_unused_var(self): ''' remove unused varibles in program ''' args = [] for i in range(len(self.block.ops)): current_op = self.block.ops[i] args += current_op.input_arg_names args += current_op.output_arg_names args = list(set(args)) # unique the input and output arguments for var in self.block.vars.keys(): if var not in args: self.block.remove_var(var)