HP Fortran Programmer's Guide (B3908-90031; September 2011)

Performance and optimization
Using options to control optimization
Chapter 6152
+O[no]conservative +O2 or higher Suppress [do not suppress] optimizations that
assume strict conformity to the Fortran 90
standard. The default is +Onoconservative.
For more information about this option, see
“Conservative vs. aggressive optimization” on
page 162.
NOTE: This option is valid only on the PA-RISC
systems.
+O[no]limit +O2 or higher Enable [disable] optimizations that do not make
large demands on system resources. The default is
+Onolimit.
+O[no]size +O2 or higher Enable [disable] optimizations that do not
significantly increase code size. The default is
+Onosize.
Table 6-3 Fine-tuning optimization options
Option Level Function
+O[no]cache_pad_common +O3 or higher Pad [do not pad] common blocks to avoid cache
collisions. The default is
+Onocache_pad_common.
+O[no]dataprefetch +O2 or higher Insert [do not insert] instructions within
innermost loops to explicitly prefetch data from
memory into the data cache. The default is
+Onodataprefetch.
Table 6-2 Packaged optimization options (Continued)
Option Level Function