burn_autodiff/
backend.rs

1use crate::{
2    checkpoint::strategy::{CheckpointStrategy, NoCheckpointing},
3    grads::Gradients,
4    runtime::AutodiffClient,
5    tensor::AutodiffTensor,
6};
7use alloc::{format, string::String};
8use burn_backend::{
9    backend::{AutodiffBackend, Backend, ExecutionError},
10    tensor::{BoolTensor, IntTensor, QuantizedTensor},
11};
12use core::marker::PhantomData;
13
14/// Enable auto-differentiation on a backend.
15///
16/// This works as a backend decorator, extending the functionality of any backend with
17/// backpropagation.
18#[derive(Clone, Copy, Debug, Default)]
19pub struct Autodiff<B, C = NoCheckpointing> {
20    _b: PhantomData<B>,
21    _checkpoint_strategy: PhantomData<C>,
22}
23
24impl<B: Backend, C: CheckpointStrategy> Backend for Autodiff<B, C> {
25    type Device = B::Device;
26
27    type FloatTensorPrimitive = AutodiffTensor<B>;
28    type FloatElem = B::FloatElem;
29
30    type IntTensorPrimitive = B::IntTensorPrimitive;
31    type IntElem = B::IntElem;
32
33    type BoolTensorPrimitive = B::BoolTensorPrimitive;
34    type BoolElem = B::BoolElem;
35
36    type QuantizedTensorPrimitive = B::QuantizedTensorPrimitive;
37
38    fn ad_enabled() -> bool {
39        true
40    }
41
42    fn name(device: &Self::Device) -> String {
43        format!("autodiff<{}>", B::name(device))
44    }
45
46    fn seed(device: &B::Device, seed: u64) {
47        B::seed(device, seed)
48    }
49
50    fn sync(device: &B::Device) -> Result<(), ExecutionError> {
51        B::sync(device)
52    }
53
54    fn memory_persistent_allocations<Output, Input, Func: Fn(Input) -> Output>(
55        device: &Self::Device,
56        input: Input,
57        func: Func,
58    ) -> Output {
59        B::memory_persistent_allocations(device, input, func)
60    }
61
62    fn memory_cleanup(device: &Self::Device) {
63        B::memory_cleanup(device)
64    }
65
66    fn staging<'a, Iter>(data: Iter, device: &Self::Device)
67    where
68        Iter: Iterator<Item = &'a mut burn_backend::TensorData>,
69    {
70        B::staging(data, device);
71    }
72
73    fn supports_dtype(device: &Self::Device, dtype: burn_std::DType) -> bool {
74        B::supports_dtype(device, dtype)
75    }
76}
77
78impl<B: Backend, C: CheckpointStrategy> AutodiffBackend for Autodiff<B, C> {
79    type InnerBackend = B;
80    type Gradients = Gradients;
81
82    fn backward(tensor: AutodiffTensor<B>) -> Gradients {
83        let client = tensor.node.client.clone();
84
85        AutodiffClient::backward::<B>(&client, tensor)
86    }
87
88    fn grad(tensor: &AutodiffTensor<B>, grads: &Gradients) -> Option<B::FloatTensorPrimitive> {
89        grads.get::<B>(tensor)
90    }
91
92    fn grad_remove(
93        tensor: &AutodiffTensor<B>,
94        grads: &mut Gradients,
95    ) -> Option<B::FloatTensorPrimitive> {
96        grads.remove::<B>(tensor)
97    }
98    fn inner(tensor: AutodiffTensor<B>) -> B::FloatTensorPrimitive {
99        tensor.primitive
100    }
101
102    fn from_inner(tensor: B::FloatTensorPrimitive) -> AutodiffTensor<B> {
103        AutodiffTensor::new(tensor)
104    }
105
106    fn grad_replace(
107        tensor: &AutodiffTensor<B>,
108        grads: &mut Self::Gradients,
109        grad: B::FloatTensorPrimitive,
110    ) {
111        grads.remove::<B>(tensor);
112        grads.register::<B>(tensor.node.id, grad);
113    }
114
115    fn int_inner(tensor: IntTensor<Self>) -> IntTensor<Self::InnerBackend> {
116        tensor
117    }
118
119    fn bool_inner(tensor: BoolTensor<Self>) -> BoolTensor<Self::InnerBackend> {
120        tensor
121    }
122
123    fn int_from_inner(tensor: IntTensor<Self::InnerBackend>) -> IntTensor<Self> {
124        tensor
125    }
126
127    fn bool_from_inner(tensor: BoolTensor<Self::InnerBackend>) -> BoolTensor<Self> {
128        tensor
129    }
130
131    fn q_inner(tensor: QuantizedTensor<Self>) -> QuantizedTensor<Self::InnerBackend> {
132        tensor
133    }
134
135    fn q_from_inner(tensor: QuantizedTensor<Self::InnerBackend>) -> QuantizedTensor<Self> {
136        tensor
137    }
138}
burn_autodiff/backend.rs

burn_autodiff/
backend.rs
