HP Fortran Programmer Guide HP-UX 11i v1, HP-UX 11i v2, and HP-UX 11i v3 (B3908-90032,December 2012)

Loop unrolling and jamming increases register
exploitation.
+Omoveflopsallows the optimizer to move conditional
floating-point instructions, enabling other optimizations
+O[no]moveflop
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 +Onomoveflopsis 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.
.
+Omultiprocessortells the compiler to appropriately
optimize several different processes on multiprocessor
+Oprefetch
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.
+Oopenmpallows users to enable the OpenMP directives.
+Onoopenmpwill disable the OpenMP directives.
+O[no]openmp
+O[no]openmpis accepted at all optimization levels.
The default is +Onoopenmp.
+Oparallelcauses the compiler to transform eligible
loops for parallel execution on multiprocessor machines.
+O[no]parallel
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 +Oparalleloption, you must link
with the f90 command and specify the
+Oparalleloption to link in the correct runtime support.
The +Onoparalleloption disables parallelization for
the target program. It is the default at all levels of
optimization. The +Oparalleloption is not available
on Itanium®-based systems for HP Fortran Version 3.2
and later. You can use the +Oautoparoption instead of
+Oparallelon Itanium® based systems.
NOTE: The +Oparalleloption should not be used for
programs that make explicit calls to the kernel threads
library.
+Oparallel_intrinsicslinks in the parallel version
of many of the Fortran intrinsics located in
libF90_parallel.
+Oparallel_intrinsics
+Oparmsoverlapcauses the optimizer to assume that
the actual arguments of function calls overlap in memory,
+O[no]parmsoverlap
thus preventing any optimizations that violate this
assumption. This option is only effective at optimization
level 2 or higher.
Use the +Onoparmsoverlapoption with programs that
conform to the standard requirement that parameters
must not overlap
The default is+Onoparmsoverlap.
+Opipelineenables software pipelining. This option is
only effective at optimization level 2 or higher. Use
+O[no]pipeline
+Onopipeline(disable software pipelining) to conserve
code space. The default is +Opipeline.
Fine-tuning optimization options 45