Input data for an atomic instruction.
Optionally, this operand may be used to store output data:
If glc is specified, gets the memory value before the operation.
Size: depends on dmask:
dmask may specify 2 data elements for 32-bit-per-pixel surfaces or 4 data elements for 64-bit-per-pixel surfaces. Each data element occupies 1 dword.
Note: the surface data format is indicated in the image resource constant, but not in the instruction.