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| # Copyright 2020 The HuggingFace Team. 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 math | |
| import tensorflow as tf | |
| from packaging import version | |
| def _gelu(x): | |
| """ | |
| Gaussian Error Linear Unit. Original Implementation of the gelu activation function in Google Bert repo when | |
| initially created. For information: OpenAI GPT's gelu is slightly different (and gives slightly different results): | |
| 0.5 * x * (1 + torch.tanh(math.sqrt(2 / math.pi) * (x + 0.044715 * torch.pow(x, 3)))) Also see | |
| https://arxiv.org/abs/1606.08415 | |
| """ | |
| x = tf.convert_to_tensor(x) | |
| cdf = 0.5 * (1.0 + tf.math.erf(x / tf.cast(tf.sqrt(2.0), x.dtype))) | |
| return x * cdf | |
| def _gelu_new(x): | |
| """ | |
| Gaussian Error Linear Unit. This is a smoother version of the GELU. Original paper: https://arxiv.org/abs/1606.0841 | |
| Args: | |
| x: float Tensor to perform activation | |
| Returns: | |
| `x` with the GELU activation applied. | |
| """ | |
| x = tf.convert_to_tensor(x) | |
| pi = tf.cast(math.pi, x.dtype) | |
| coeff = tf.cast(0.044715, x.dtype) | |
| cdf = 0.5 * (1.0 + tf.tanh(tf.sqrt(2.0 / pi) * (x + coeff * tf.pow(x, 3)))) | |
| return x * cdf | |
| def mish(x): | |
| x = tf.convert_to_tensor(x) | |
| return x * tf.tanh(tf.math.softplus(x)) | |
| def gelu_fast(x): | |
| x = tf.convert_to_tensor(x) | |
| coeff1 = tf.cast(0.044715, x.dtype) | |
| coeff2 = tf.cast(0.7978845608, x.dtype) | |
| return 0.5 * x * (1.0 + tf.tanh(x * coeff2 * (1.0 + coeff1 * x * x))) | |
| if version.parse(tf.version.VERSION) >= version.parse("2.4"): | |
| def approximate_gelu_wrap(x): | |
| return tf.keras.activations.gelu(x, approximate=True) | |
| gelu = tf.keras.activations.gelu | |
| gelu_new = approximate_gelu_wrap | |
| else: | |
| gelu = _gelu | |
| gelu_new = _gelu_new | |
| ACT2FN = { | |
| "gelu": gelu, | |
| "relu": tf.keras.activations.relu, | |
| "swish": tf.keras.activations.swish, | |
| "silu": tf.keras.activations.swish, | |
| "gelu_new": gelu_new, | |
| "mish": mish, | |
| "tanh": tf.keras.activations.tanh, | |
| "gelu_fast": gelu_fast, | |
| } | |
| def get_tf_activation(activation_string): | |
| if activation_string in ACT2FN: | |
| return ACT2FN[activation_string] | |
| else: | |
| raise KeyError(f"function {activation_string} not found in ACT2FN mapping {list(ACT2FN.keys())}") | |