The UNROLL Directive

The UNROLL directive requires that you specify SUN after C$PRAGMA.

The C$PRAGMA SUN UNROLL=n directive instructs the compiler to unroll loops n times during its optimization pass.

n is a positive integer. The choices are:

• If n=1, this directive directs the optimizer not to unroll any loops.

• If n>1, this directive suggests to the optimizer that it unroll loops n times.

If any loops are actually unrolled, the executable file becomes larger. For further information, see the Fortran Programming Guide chapter on performance and optimization.

Example - unrolling loops two times:

C$PRAGMA SUN UNROLL=2