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

Table6-2 lists the “packaged” options. These options enable or disable a set of related optimizations,
such as optimizations that do not increase code size. Table6-3 lists options that enable or disable
specific optimizations.
The options in both tables can be combined on the same command line, except as noted. For
example, the following command line requests aggressive optimizations at level 2 that do not
increase code size:
$ f90 +02 +Oaggressive +Osize prog.f90
Nearly all of the optimization options can be used to enable or disable an optimization or a
package of optimizations. For example, the following command line requests aggressive level 4
optimizations that do not result in roundoff errors:
$ f90 +O4 +Oaggressive +Ofltacc prog.f90
The f90.1 manpage fully describes all of the optimization options.
Table 28 Packaged optimization options
FunctionLevelOption
Enable [disable] optimizations that can significantly improve
performance in standard-conforming programs. The default
+O2or higher+O[no]aggressive
is +Onoaggressive. For more information about this
option, see “Conservative vs. aggressive optimization”
(page 99).
Enable [disable] maximum optimization. The default is
+Onoall.
Invokes highest level+O[no]all
Do [do not] automatically parallelize loops that are deemed
safe and profitable by the loop parallelizer. The default is
+O[no]autopar
+Onoautopa. The +Oautopar option can be used for
programs at optimization levels, +O3and above.
If both +Oopenmpand +Oautopar are specified on the
command line, the OpenMP directives gain precedence
over the +Oautoparoption. The compiler auto-parallelizes
only the loops of code that are not controlled by the
OpenMP directives.
To compile a program with +Oautoparsupport, the
libcps, libomp, and libpthreads runtime support
libraries must be present at compile-time and runtime. This
feature is available on Integrity systems and HP 9000
systems.
Suppress [do not suppress] optimizations that assume strict
conformity to the Fortran90 standard. The default is
+O2or higher+O[no]conservative
+Onoconservative. For more information about this
option, see “Conservative vs. aggressive optimization”
(page 99).
NOTE: This option is valid only on the PA-RISC systems.
Enable [disable] optimizations that do not make large
demands on system resources. The default is +Onolimit.
+O2or higher+O[no]limit
Enable [disable] optimizations that do not significantly
increase code size. The default is +Onosize.
+O2or higher+O[no]size
Table 29 Fine-tuning optimization options
FunctionLevelLevel
Pad [do not pad] common
blocks to avoid cache
+O3or higher+O[no]cache_pad_common
92 Performance and optimization