Sun Studio 12 Update 1: Fortran User's Guide 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 the following loop n times during its optimization pass. (The compiler will unroll a loop only when its analysis regards such unrolling as appropriate.)

n is a positive integer. The choices are:

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: