Directives and optimization

The following are comment form directives useful for optimizing programs. See Optimizing XL compiler programs and the compiler options that affect performance.

Assertive directives

Assertive directives gather information about source code that is otherwise unavailable to the compiler. Providing this information can increase performance.

ASSERT CNCALL
INDEPENDENT PERMUTATION

Directives for Loop Optimization

The following directives provide different methods for loop optimization:

BLOCK_LOOP LOOPID
STREAM_UNROLL UNROLL
UNROLL_AND_FUSE PREFETCH directives