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

Performance and optimization
Using options to control optimization
Chapter 6154
+Ofast All Select a combination of optimization options for
optimum execution speed and reasonable build
times. Currently chosen options are:
• +O2
• +Ofltacc=relaxed
• +Onolimit
• +DSnative
• +FPD
• -Wl,+pi,1M
• -Wl,+pd,1M
• -Wl,+mergeseg
NOTE:
Do not use this option for programs that depend
on IEEE standard floating point denormalized
numbers. Otherwise, different numerical results
may occur. See +Ofltacc=relaxed. This
option is a synonym for -fast.
+Ofaster All This option is equivalent to +Ofast with an
increased optimization level. The definition of
+Ofaster may change or it may be deprecated
in future releases.
+O[no]fltacc +O2 or higher Disable [enable] floating-point optimizations that
can result in numerical differences. By default,
the optimizer does not perform such
optimizations. For information about the effect
this option can have on your program, refer to the
HP-UX Floating-Point Guide.
+Ofrequently_called=func
tion1[,function2...]
All The named functions are assumed to be
frequently called. This option overrides any
information in a profile database.
Table 6-3 Fine-tuning optimization options (Continued)
Option Level Function