burn-cubecl 0.21.0-pre.4

Generic backend that can be compiled just-in-time to any shader language target
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80

use crate::{CubeRuntime, kernel::utils::address_type, tensor::CubeTensor};
use crate::{kernel::utils::shape_divmod, ops::numeric::empty_device_dtype};
use burn_backend::TensorMetadata;
use cubecl::{CubeDim, calculate_cube_count_elemwise, std::tensor::layout::linear::LinearView};
use cubecl::{prelude::*, std::FastDivmod};

#[cube(launch_unchecked, address_type = "dynamic")]
fn select_kernel<T: Numeric, I: Numeric>(
    input: &Tensor<T>,
    indices: &LinearView<I>,
    output: &mut LinearView<T, ReadWrite>,
    out_shape: Sequence<FastDivmod<usize>>,
    dim: usize,
    #[define(T, I)] _dtypes: [StorageType; 2],
) {
    if ABSOLUTE_POS >= output.shape() {
        terminate!();
    }

    let rank = out_shape.len().comptime();

    let mut offset = ABSOLUTE_POS;
    let mut offset_input = 0;

    #[unroll]
    for i in 0..rank {
        let i = rank - i - 1;
        let (rem, offset_local) = out_shape[i].div_mod(offset);
        offset = rem;

        let offset_local = cubecl::prelude::select(
            i == dim,
            usize::cast_from(indices[offset_local]),
            offset_local,
        );

        offset_input += offset_local * input.stride(i);
    }

    output[ABSOLUTE_POS] = input[offset_input];
}

pub(crate) fn select<R: CubeRuntime>(
    tensor: CubeTensor<R>,
    dim: usize,
    indices: CubeTensor<R>,
) -> CubeTensor<R> {
    let mut shape_output = tensor.shape();
    shape_output[dim] = indices.meta.shape()[0];
    let total_elem = shape_output.num_elements();

    let output = empty_device_dtype(
        tensor.client.clone(),
        tensor.device.clone(),
        shape_output,
        tensor.dtype,
    );

    let working_units = total_elem;
    let cube_dim = CubeDim::new(&indices.client, working_units);
    let cube_count = calculate_cube_count_elemwise(&indices.client, working_units, cube_dim);

    let (tensor_dtype, indices_dtype) = (tensor.dtype, indices.dtype);

    unsafe {
        select_kernel::launch_unchecked(
            &output.client,
            cube_count,
            cube_dim,
            address_type!(tensor, indices, output),
            tensor.into_tensor_arg(),
            indices.into_linear_view(),
            output.clone().into_linear_view(),
            shape_divmod(&output),
            dim,
            [tensor_dtype.into(), indices_dtype.into()],
        )
    };
    output
}