Function constant_pad2d_forward 

pub fn constant_pad2d_forward<T: Triton, D: Num, const PT: i32, const PB: i32, const PL: i32, const PR: i32, const BLOCK_OW: i32>(
    input_ptr: T::Pointer<D>,
    output_ptr: T::Pointer<D>,
    _B: i32,
    C: i32,
    H: i32,
    W: i32,
    OH: i32,
    OW: i32,
    value: f32,
)
where
    T::I32Tensor: Tensor<i32, 1> + Comparison<i32, BoolTensor = T::BoolTensor>,
    T::BoolTensor: BitAnd<Output = T::BoolTensor> + BitOr<Output = T::BoolTensor>,
    T::Pointer<D>: AddOffsets<i32, 1, T::I32Tensor, Output = T::Tensor<T::Pointer<D>>>,

2-D constant padding forward pass.

Grid: pid = ((b * C + c) * OH + oh) * num_ow_tiles + ow_tile

OH = PT + H + PB, OW = PL + W + PR. Positions outside input region are filled with value.