HP Fortran Programmer Guide (766160-001, March 2014)

+Oloop_transformenables transformation of eligible
loops for improved cache performance. The most
+O[no]loop_transform
important transformation is the interchange of nested
loops to make the inner loop unit stride, resulting in fewer
cache misses. +Onoloop_transform disables
transformation of eligible loops. The default is
+Oloop_transform.
NOTE: This option is deprecated and not supported in
future releases. Use +inline_level.
This option controls inlining in fortran. The format for num
is N[.n], where num is either an integral value from0
+inline_level num
to 9 or a value with a single decimal place from 0.0to
9.0. For more information on this option, see
F90(1)manpage.
+Oloop_unrollturns on loop unrolling. factor is the
unroll factor that controls the code expansion. The default
+O[no]loop_unroll[=factor]
unroll factor is 4; that is, four copies of the loop body.
By experimenting with different factors, you may improve
the performance of your program. This option is only
effective at optimization level 2 or higher. The default is
+Oloop_unroll=4.
+loop_unroll_jamenables loop unrolling and
jamming. +Onoloop_unroll_jam (the default) disables
+O[no]loop_unroll_jam
both automatic and directive-specified unroll and jam.
Loop unrolling and jamming increases register
exploitation.
+Omoveflops allows 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 +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.
+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.
+Oopenmp allows 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.
+Oparallel causes 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 +Oparallel option, you must link
with the f90 command and specify the
+Oparalleloption 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
46 Compiling and linking