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Python

# coding=utf-8
# Copyright (c) 2020, NVIDIA CORPORATION. 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.
"""Utilities for models."""
import math
import torch
def init_method_normal(sigma):
"""Init method based on N(0, sigma)."""
def init_(tensor):
return torch.nn.init.normal_(tensor, mean=0.0, std=sigma)
return init_
def scaled_init_method_normal(sigma, num_layers):
"""Init method based on N(0, sigma/sqrt(2*num_layers)."""
std = sigma / math.sqrt(2.0 * num_layers)
def init_(tensor):
return torch.nn.init.normal_(tensor, mean=0.0, std=std)
return init_
def attention_mask_func(attention_scores, attention_mask):
attention_scores.masked_fill_(attention_mask, -10000.0)
return attention_scores
def get_linear_layer(rows, columns, init_method):
"""Simple linear layer with weight initialization."""
layer = torch.nn.Linear(rows, columns)
init_method(layer.weight)
with torch.no_grad():
layer.bias.zero_()
return layer
def fast_gelu(x):
"""Mindspore's fast gelu implementation."""
return x / (1 + torch.exp(-1.702 * torch.abs(x))) * torch.exp(0.851 * (x - torch.abs(x)))
@torch.jit.script
def gelu_impl(x):
"""OpenAI's gelu implementation."""
return (
0.5 * x * (1.0 + torch.tanh(0.7978845608028654 * x * (1.0 + 0.044715 * x * x)))
)
def openai_gelu(x):
return gelu_impl(x)
# This is actually Python equivalent of torch.nn.functional.gelu(), also with type hints for ONNX exporter
@torch.jit.script
def erf_gelu(x):
return (
x
* 0.5
* (
torch.erf(x / 1.41421).to(dtype=x.dtype)
+ torch.ones_like(x).to(dtype=x.dtype)
)
)