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Paddle/python/paddle/fluid/inference_transpiler.py

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# 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.
2. fuse the batch_norm's parameters to conv and elementwise_add operators.
3. remove batch_norm ops which are not used in any other ops.
4. adjust the input of any_other_op to be the output of elementwise_add operator.
5. 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)
self.input_map = {} # store the input names should be adjusted
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]
# conv2d without bias
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, 0)
# remove batch_norm_op
self.block.remove_op(i + 2)
i = i + 1
# conv2d with bias, the next_op.type is elementwise_add
elif (next_op.type == 'elementwise_add'):
next_next_op = self.block.ops[i + 2]
if (next_next_op.type == 'batch_norm'):
# fuse batch_norm
self._fuse_param(current_op, next_next_op, next_op, 1)
# remove batch_norm_op
self.block.remove_op(i + 2)
i = i + 1
i = i + 1
self._adjust_input()
self._remove_unused_var()
# TODO(luotao): use clone() method to flush the program.desc in force,
# since some large program.desc will not be flushed immediately.
# And a better solution will be considered later.
return program.clone()
# ====================== 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, with_bias):
'''
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
:param with_bias: If current operator has bias, with_bias = 1; otherwise 0.
:type with_bias: Int
'''
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
if with_bias:
bias = _load_param(bias_op.input("Y"))
else:
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)
# collect the renamed input
self.input_map[bn_op.output("Y")[0]] = bias_op.output("Out")[0]
def _adjust_input(self):
for i in range(len(self.block.ops)):
current_op = self.block.ops[i]
for input_arg in current_op.input_arg_names:
if input_arg in self.input_map:
current_op.rename_input(input_arg,
self.input_map[input_arg])
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)