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

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.
NOTE: The +Oparallel option should not be used
for programs that make explicit calls to the kernel threads
library.
+Oparallel_intrinsics links in the parallel version
of many of the Fortran intrinsics located in
libF90_parallel.
+Oparallel_intrinsics
+Oparmsoverlap causes 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.
NOTE: This option is valid only on the PA-RISC systems.
Applies to loops for which the compiler generates data
prefetch instructions. For a given loop, the compiler
+Oprefetch_latency=num option
divides “cycles” by the estimated loop length to arrive
at the number of loop iterations for which to generate
advance prefetches. The default value is 480 cycles for
loops containing floating-point accesses and 150 cycles
for loops that do not contain any floating-point accesses.
For tuning purposes, it is recommended that users
measure their application’s performance using a few
different prefetch latency settings to determine the optimal
value. Some floating-point codes may benefit by
increasing the distance to 960. Parallel applications
frequently benefit from a shorter prefetch distance of 150.
When +Oprocelimis specified, procedures that are not
referenced by the application are eliminated from the
+O[no]procelim
output executable file. When +Onoprocelim is
specified, procedures that are not referenced by the
application are not eliminated from the output executable
file. You can use this option at any level of optimization.
Use +Oprocelimto reduce the size of the executable
file, especially when optimizing at levels 3 and 4, when
inlining can remove all calls to some routines.
The default is +Onoprocelimat levels 0-3, and
+Oprocelimat level 4.
Specify filname as the name of the profile database file.
This option is a synonym for the +P, +dffilename
+Oprofile=use:filename
options.The :filename argument is optional (the default
filename is flow.data). See ld (1), +P, and +df for
more details. This option is only valid for Itanium®-based
applications.
In the absence of qualifiers, +Oprofile=collectis
the same as +I.
&lt qualifiers &gt are a comma-separated list of profile
collection qualifiers. Supported profile collection qualifiers
are :
+Oprofile=collect&ltqualifiers&gt
Fine-tuning optimization options 47