HP Fortran Programmer's Guide (March 2010)

Compiling and linking
Compiling with the f90 command
Chapter 2 67
Note the following precautions when using this option:
• All program modules that reference the common block must be compiled
with the +Ocache_pad_common option.
• Each common block in the program should have the same layout in all
program units within which it is declared. If the layouts are different,
they must be fully independent—that is, they must not pass values
between them.
The default, +Onocache_pad_common, disables padding.
+O[no]cxlimitedrange
Enables [disables] the use of floating point math in the compilation unit.
The default is +Onocxlimitedrange.
+O[no]cross_region_addressing
Enable [disable] the use of cross-region addressing. Cross-region addressing
is required if a pointer (such as an array base) points to a different region
than the data being addressed. This is usually due to an offset which results
in a cross-over into another region. Standard-conforming applications do not
require the use of cross-region addressing.
The default is +onocross_region_addressing.
+O[no]dataprefetch
+Odataprefetch causes the optimizer to insert instructions within
innermost loops to explicitly prefetch data from memory into the data cache.
Data prefetch instructions will be inserted only for data structures
referenced within innermost loops using simple loop varying
addresses—that is, in a simple arithmetic progression. It is not available for
PA-RISC 1.1 targets.
Use this option for applications that have high data cache miss overhead.
The default is +Onodataprefetch. On HP-UX version 11i and later,
+Odataprefetch is the same as +Odataprefetch=indirect and
+Onodataprefetch is the same as +Odataprefetch=none. At +O2 and
higher, the default is +Odataprefetch.
+O[no]dataprefetch=[direct|indirect|none]
Control generation of data prefetch instructions for data structures
referenced within innermost loops. The defined values for kind are: