Enable unrolling of DO loops where possible.
n is a positive integer. The choices are:
n=1 inhibits all loop unrolling.
n>1 suggests to the optimizer that it attempt to unroll loops n times.
Loop unrolling generally improves performance, but will increase the size of the executable file. For more information on this and other compiler optimizations, see the “Performance and Optimization” chapter in the Fortran Programming Guide. See also 18.104.22.168 The UNROLL Directive.