CUDA Specifics

Function attributes

The cuda_kernel function kind has the following attributes: - attrs.cuda.block_dim (required): the block dimensions - attrs.cuda.grid_dim (required): the grid dimensions - attrs.cuda.dynamic_smem_bytes (optional): the dynamic shared memory size to use - attrs.cuda.min_blocks (optional): the minimum number of blocks this kernel will be launched.

Memory scope

To define a tensor that resides in the shared memory, we can specify the scope argument of the hidet.lang.types.tensor constructor:

from hidet.lang.types import tensor, f32, DeclareScope

# define a tensor in the shared memory
a = tensor(dtype=f32, shape=[10, 10], scope='shared')   # use the string to specify the scope
b = tensor(dtype=f32, shape=[10, 10], scope=DeclareScope.Shared)  # use the enum to specify the scope

# similarly, we can define a tensor that resides in the register file
# please note that each thread will have a f32[10, 10] tensor
c = tensor(dtype=f32, shape=[10, 10], scope='register')
d = tensor(dtype=f32, shape=[10, 10], scope=DeclareScope.Register)

Primitive functions

Hidet provides some primitive functions that can be used in the cuda kernel functions. The primitive functions are defined in the hidet.lang.cuda module. The following table lists the commonly used primitive functions:


make a full list in the reference section.

  • threadIdx, blockIdx, blockDim, gridDim: the thread index, block index, block dimension and grid dimension.

  • syncthreads(): synchronize all threads in the same block.

  • ldmatrix(...): load a matrix from shared memory to the register file.

  • mma_sync(...): perform matrix-matrix multiplication using the tensor cores.

  • atomic_add(...): perform atomic add operation (other atomic functions like atomic_max are also included).

  • shfl_sync(...): warp shuffle operation.

  • dynamic_shared_memory(...): access the dynamic allocated shared memory

Please refer to the hidet.lang.cuda module for the complete list of supported primitive functions