This directive emits size bytes filled with no-op instructions. size is absolute expression, which must be a positve value. control controls how no-op instructions should be generated. If the comma and control are omitted, control is assumed to be zero.
Note: For Intel 80386 and AMD x86-64 targets, control specifies the size limit of a no-op instruction. The valid values of control are between 0 and 4 in 16-bit mode, between 0 and 7 when tuning for older processors in 32-bit mode, between 0 and 11 in 64-bit mode or when tuning for newer processors in 32-bit mode. When 0 is used, the no-op instruction size limit is set to the maximum supported size.