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Mojo function

st_matrix

st_matrix[dtype: DType, //, simd_width: Int, *, transpose: Bool = False](ptr: UnsafePointer[SIMD[dtype, 1], address_space=AddressSpace(3)], d: SIMD[float32, simd_width])

Performs warp-synchronized copy from registers to shared memory.

This function stores data from registers to shared memory in a format that can be directly used by tensor core Matrix Multiply-Accumulate (MMA) instructions. It uses the NVIDIA stmatrix instruction to perform an efficient warp-synchronized store.

Note: The function performs a warp-synchronized operation - all threads in the warp must execute this instruction to avoid deadlock.

Constraints:

  • Must be used with shared memory pointers. - Number of registers must be 1, 2, or 4. - Data must be properly aligned for matrix operations. - All threads in warp must participate. - Only supported on NVIDIA GPUs with tensor core capabilities.

Parameters:

  • ​dtype (DType): Data type of elements to store.
  • ​simd_width (Int): Width of the SIMD vector.
  • ​transpose (Bool): If True, transposes the matrix during store.

Args:

  • ​ptr (UnsafePointer[SIMD[dtype, 1], address_space=AddressSpace(3)]): Pointer to shared memory where data will be stored.
  • ​d (SIMD[float32, simd_width]): SIMD vector containing the data to store.