HP Fortran Programmer's Guide (B3908-90031; September 2011)

Performance and optimization
Chapter 6142
for compatibility with the POSIX standard and has the same functionality as the +O2 option.
The following command line compiles prog.f90, using the default level of optimization:
$ f90 -O prog.f90
For most applications, -O provides effective optimization. However, some applications can realize
significant increases in performance at higher levels of optimization or when you use other features of the
optimizer to boost performance. This chapter discusses these features as well as the following topics:
• Using profilers
• Using options to control optimization
• Conservative vs. aggressive optimization
• Parallelizing HP Fortran programs
• Vectorization
• Controlling code generation for performance
For information about getting the best performance from floating-point intensive applications running on
HP-UX, see the HP-UX Floating-Point Guide.