riciii7/FastAPI-Batik-GAN

1# Copyright (c) 2021, NVIDIA CORPORATION.  All rights reserved.2#3# NVIDIA CORPORATION and its licensors retain all intellectual property4# and proprietary rights in and to this software, related documentation5# and any modifications thereto.  Any use, reproduction, disclosure or6# distribution of this software and related documentation without an express7# license agreement from NVIDIA CORPORATION is strictly prohibited.8 9"""Fused multiply-add, with slightly faster gradients than `torch.addcmul()`."""10 11import torch12 13#----------------------------------------------------------------------------14 15def fma(a, b, c): # => a * b + c16    return _FusedMultiplyAdd.apply(a, b, c)17 18#----------------------------------------------------------------------------19 20class _FusedMultiplyAdd(torch.autograd.Function): # a * b + c21    @staticmethod22    def forward(ctx, a, b, c): # pylint: disable=arguments-differ23        out = torch.addcmul(c, a, b)24        ctx.save_for_backward(a, b)25        ctx.c_shape = c.shape26        return out27 28    @staticmethod29    def backward(ctx, dout): # pylint: disable=arguments-differ30        a, b = ctx.saved_tensors31        c_shape = ctx.c_shape32        da = None33        db = None34        dc = None35 36        if ctx.needs_input_grad[0]:37            da = _unbroadcast(dout * b, a.shape)38 39        if ctx.needs_input_grad[1]:40            db = _unbroadcast(dout * a, b.shape)41 42        if ctx.needs_input_grad[2]:43            dc = _unbroadcast(dout, c_shape)44 45        return da, db, dc46 47#----------------------------------------------------------------------------48 49def _unbroadcast(x, shape):50    extra_dims = x.ndim - len(shape)51    assert extra_dims >= 052    dim = [i for i in range(x.ndim) if x.shape[i] > 1 and (i < extra_dims or shape[i - extra_dims] == 1)]53    if len(dim):54        x = x.sum(dim=dim, keepdim=True)55    if extra_dims:56        x = x.reshape(-1, *x.shape[extra_dims+1:])57    assert x.shape == shape58    return x59 60#----------------------------------------------------------------------------61