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

Compiling and linking
Compiling with the f90 command
Chapter 272
+loop_unroll_jam enables loop unrolling and jamming. +Onoloop_unroll_jam
(the default) disables both automatic and directive-specified unroll and jam. Loop
unrolling and jamming increases register exploitation.
+O[no]moveflop
+Omoveflops allows the optimizer to move conditional floating-point instructions,
enabling other optimizations to occur. This option is only effective at optimization level
2 or higher.
The behavior of floating-point exception handling may be altered by this option.
Using +Onomoveflops is recommended if floating-point traps are enabled and you do
not want the behavior of floating-point exceptions to be altered by the relocation of
floating-point instructions, as when your program uses the ON statement. The default is
+Omoveflops.
+O[no]multiprocessor
+Omultiprocessor tells the compiler to appropriately optimize several different
processes on multiprocessor machines. The optimizations are those appropriate for
executables and or shared libraries. +Onomultiprocessor, the default, disables the
optimization of more than one process running on a multiprocessor machine.
NOTE This option is valid only on the PA-RISC systems.
+O[no]openmp +Oopenmp allows users to enable the OpenMP directives. +Onoopenmp will disable
the OpenMP directives. +O[no]openmp is accepted at all optimization levels. The
default is +Onoopenmp.
+O[no]parallel
+Oparallel causes the compiler to transform eligible loops for parallel execution on
multiprocessor machines. This option is effective only at optimization level 3 or higher.
This option is available only on HP 9000 systems.
If you link separately from the command line and compile the program with the
+Oparallel option, you must link with the f90 command and specify the
+Oparallel option to link in the correct runtime support.
The +Onoparallel option disables parallelization for the target program. It is the
default at all levels of optimization.
The +Oparallel option is not available on Itanium-based systems for HP Fortran
Version 3.2 and later. You can use the +Oautopar option instead of +Oparallel on
Itanium-based systems.