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

Compiling and linking
Compiling with the f90 command
Chapter 268
+O[no]fltacc=[strict|default|limited|relaxed]
Control the level of floating point optimizations that the compiler may perform. The
defined values for optlevel are:
strict—disallow any floating point optimization that can result in numerical
differences. This is the same as +Ofltacc.
default—allow contractions, such as fused multiply-add (FMA), but disallows any
other floating point optimization that can result in numerical differences.
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.
+Onofltacc Yes Yes
Table 2-9 Optimizations performed by +O[no]fltacc (Continued)
+O[no]fltacc Expression reordering? FMA?