Function cosine_embedding_loss_forward 

pub fn cosine_embedding_loss_forward<T: Triton, const BLOCK_SIZE: i32>(
    x1_ptr: T::Pointer<f32>,
    x2_ptr: T::Pointer<f32>,
    y_ptr: T::Pointer<f32>,
    out_ptr: T::Pointer<f32>,
    _n_rows: i32,
    n_dim: i32,
    margin: f32,
)
where
    T::I32Tensor: Tensor<i32, 1> + Comparison<i32, BoolTensor = T::BoolTensor>,
    T::Pointer<f32>: AddOffsets<i32, 1, T::I32Tensor, Output = T::Tensor<T::Pointer<f32>>>,

Cosine embedding loss forward (per-row).

cos_sim = dot(x1[n], x2[n]) / (||x1[n]|| * ||x2[n]||)
out[n]  = 1 - cos_sim              if y[n] ==  1
        = max(0, cos_sim - margin) if y[n] == -1

Grid: [n_rows, 1, 1]. BLOCK_SIZE must equal next_power_of_two(n_dim).