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

Compiling and linking
Compiling with the f90 command
Chapter 2 63
+Oconservative causes the optimizer to make conservative assumptions about the
code when optimizing it. This option is only effective at optimization level 2 or higher.
The +Oconservative option sets the following options:
• +Ofltacc
• +Onofltacc
• +Onomoveflops
• +Oparmsoverlap
Use +Oconservative when conservative assumptions are necessary due to the coding
style, as with nonstandard-conforming programs. Note that it is incompatible with
+Oaggressive.
The +Onoconservative option relaxes the optimizer’s assumptions about the target
program.
The default is +Onoconservative. This option has been deprecated starting with
HP-UX version 11i and later.
+O[no]limit
+Olimit suppresses optimizations that significantly increase compilation time or that
can consume large amounts of memory at compile time. This option is only effective at
optimization level 2 or higher.
The +Onolimit option allows optimizations to be performed regardless of their effect
on compilation time or memory usage.
The default is +Olimit.
+O[no]loop_transform
Enables [disables] the following transformations: loop unroll and jam, loop distribution,
loop interchange, loop blocking, loop fusion, and loop unroll.
The default is +Oloop_transform.
+O[no]size
+Osize suppresses optimizations that significantly increase code size. This option is
only effective at optimization level 2 or higher.
The +Onosize option permits optimizations that can increase code size.
The default is +Onosize.