HP Fortran Programmer's Guide (March 2010)

Performance and optimization
Using options to control optimization
Chapter 6158
+inline_level num All This option controls inlining in fortran.
The format for num is N[.n], where num is
either an integral value from 0 to 9 or a
value with a single decimal place from 0.0
to 9.0.
For more information on this option, see
F90(1) manpage.
+O[no]libcalls All Substitute [do not substitute] millicode
versions of specific intrinsics. The default
is +Olibcalls.
+O[no]loop_block +O3 or
higher
Loop blocking is a combination of strip
mining and interchange that improves
data cache locality. It is provided primarily
to deal with nested loops that manipulate
arrays that are too large to fit into the data
cache. Under certain circumstances, loop
blocking allows reuse of these arrays by
transforming the loops that manipulate
them so that they manipulate strips of the
arrays that fit into the cache.
+O[no]loop_transform +O2 or
higher
This option transforms [does not
transform] eligible loops for improved
cache and other performance.
The default is +Oloop_transform.
+O[no]loop_unroll=n +O2 or
higher
Unroll [do not unroll] program loops by a
factor of n. The default is
+Oloop_unroll=4.
Table 6-3 Fine-tuning optimization options (Continued)
Option Level Function