147 lines
4.5 KiB
Python
147 lines
4.5 KiB
Python
# Licensed to the Apache Software Foundation (ASF) under one
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# or more contributor license agreements. See the NOTICE file
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# distributed with this work for additional information
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# regarding copyright ownership. The ASF licenses this file
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# to you under the Apache License, Version 2.0 (the
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# "License"); you may not use this file except in compliance
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# with the License. You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing,
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# software distributed under the License is distributed on an
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# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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# KIND, either express or implied. See the License for the
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# specific language governing permissions and limitations
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# under the License.
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"""Batch normalization."""
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from functools import reduce
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from tvm import te, topi
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def batch_norm(
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data: te.Tensor,
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gamma: te.Tensor,
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beta: te.Tensor,
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moving_mean: te.Tensor,
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moving_var: te.Tensor,
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axis: int | None = None,
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epsilon: float | None = None,
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center: bool | None = None,
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scale: bool | None = None,
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training: bool | None = None,
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momentum: float | None = None,
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) -> list[te.Tensor]:
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"""Batch normalization layer (Ioffe and Szegedy, 2014).
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Normalizes the input at each batch, i.e. applies a transformation
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that maintains the mean activation close to 0 and the activation
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standard deviation close to 1.
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Parameters
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----------
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data : tvm.te.Tensor
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Input to be batch-normalized.
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gamma : tvm.te.Tensor
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Scale factor to be applied to the normalized tensor.
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beta : tvm.te.Tensor
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Offset to be applied to the normalized tensor.
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moving_mean : tvm.te.Tensor
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Running mean of input.
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moving_var : tvm.te.Tensor
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Running variance of input.
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axis : int, optional, default=1
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Specify along which shape axis the normalization should occur.
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epsilon : float, optional, default=1e-5
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Small float added to variance to avoid dividing by zero.
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center : bool, optional, default=True
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If True, add offset of beta to normalized tensor, If False,
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beta is ignored.
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scale : bool, optional, defualt=True
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If True, scale normalized tensor by gamma. If False, gamma
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is ignored.
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training : bool, optional, defualt=False
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Indicating whether it is in training mode. If True, update
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moving_mean and moving_var.
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momentum : float, optional, default=0.1
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The value used for the moving_mean and moving_var update.
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Returns
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-------
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output : list of tvm.te.Tensor
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Normalized data with same shape as input
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moving_mean : tvm.te.Tensor
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Running mean of input.
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moving_var : tvm.te.Tensor
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Running variance of input.
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"""
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if axis is None:
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axis = 1
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if epsilon is None:
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epsilon = 1e-5
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if center is None:
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center = True
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if scale is None:
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scale = True
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if training is None:
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training = False
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if momentum is None:
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momentum = 0.1
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shape = [1] * len(data.shape)
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shape[axis] = data.shape[axis]
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data_mean = None
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data_var = None
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if training:
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reduce_axes = list(range(len(data.shape)))
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reduce_axes.remove(axis)
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shape_prod = reduce(lambda x, y: x * y, [data.shape[ax] for ax in reduce_axes], 1)
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data_mean = topi.sum(data, axis=reduce_axes) / shape_prod
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data_mean_rs = topi.reshape(data_mean, shape)
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data_var = (
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topi.sum((data - data_mean_rs) * (data - data_mean_rs), axis=reduce_axes) / shape_prod
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)
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data_var_rs = topi.reshape(data_var, shape)
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out = (data - data_mean_rs) / topi.math.sqrt(data_var_rs + epsilon)
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else:
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moving_mean_rs = topi.reshape(moving_mean, shape)
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moving_var_rs = topi.reshape(moving_var, shape)
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out = (data - moving_mean_rs) / topi.math.sqrt(moving_var_rs + epsilon)
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if scale:
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out = out * topi.reshape(gamma, shape)
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if center:
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out = out + topi.reshape(beta, shape)
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if training:
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assert 0 <= momentum <= 1, "the valid momentum range is [0, 1]."
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return [
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out,
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(1 - momentum) * moving_mean + momentum * data_mean,
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(1 - momentum) * moving_var + momentum * data_var,
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]
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# Moving mean and var aren't updated during test. To avoid
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# placeholder reuse, we multiply by 1 and return them.
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return [out, moving_mean * 1, moving_var * 1]
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