HP Fortran Programmer's Guide (September 2007)

Compiling and linking
Compiling with the f90 command
Chapter 266
limited—like default, but also allows floating point optimizations which
may affect the generation and propogation of infinities, NaNs, and the sign
of zero. Also implies +Ocxlimitedrange.
relaxed—in addition to the optimizations allowed by limited, permits
optimizations, such as reordering of expressions, even if parenthesized, that
may affect a rounding error. This is the same as +Onofltacc. Also implies
+Ocxlimitedrange.
+Ofrequently_called=function1[,function2...]
The named functions are assumed to be frequently called. This option
overrides any information in a profile database.
+Ofrequently_called:filename
The file indicated by filename contains a list of function names, separated by
spaces or newlines. These functions are assumed to be frequently called.
This option overrides any information in a profile database.
+O[no]info
+Oinfo causes the compiler to display informational messages about the
optimization process. The +Oinfo option provides feedback that can help
you to determine whether the compiler optimized time-critical sections of
your program. It can be used at any level of optimization but is most useful
at level 3.
Currently, this option provides feedback for the following optimizations:
• Cloning, the replacement of a call to a routine by a call to a clone, which
is a copy of the routine with changes specific to that call site.
• Inlining.
• Loop transformations to improve cache performance.
• Vectorization.
The default, +Onoinfo, disables the display of informational messages about
optimization.
+O[no]initcheck
The initialization checking feature of the optimizer has three possible
states: on, off, or unspecified. When this option is specified in the on state
(+Oinitcheck), the optimizer initializes to zero any local, nonarray,
nonstatic variables that are uninitialized with respect to at least one path
leading to a use of the variable.