n has the value 1 through 5 and corresponds to the optimization levels of -O1 through -O5. If not specified, the compiler uses 5.
This option enables the C$PRAGMA SUN OPT=n directive when it appears in the source input. Without this option, the compiler treats these lines as comments. See 22.214.171.124 The OPT Directive.
If this pragma appears with an optimization level greater than the maximum level on the -xmaxopt flag, the compiler uses the level set by -xmaxopt.