To output bit manipulation instructions without using intrinsic functions, satisfy all conditions shown below.
To stop the output of bit manipulation instructions, satisfy condition (c) above and either assign a value that is not a constant in condition (a) or use a type that is not a 1-byte type in condition (b).
When none of the above conditions is satisfied, the compiler automatically determines whether to output bit manipulation instructions according to the specified optimization level and the contents of the source program.