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

Performance and optimization
Conservative vs. aggressive optimization
Chapter 6 163
NOTE The +Oaggressive and +Oconservative options are valid only on the PA-RISC
systems.
+Oconservative • Nonstandard
• Sensitive to rounding
differences
• Contains floating-point
expressions that must be
evaluated in the specified
order
• Procedure arguments may
overlap
+Ofltacc
+Onomoveflops
+Oparmsoverlap
+Oaggressive • Standard-conforming
• Contains floating-point
expressions that permit
re-ordering for optimization
• Does not contain
uninitialized variables
+Oentrysched
+Onofltacc
+Onoinitcheck
+Ovectorize
Table 6-4 Conservative, aggressive, and default optimizations
Specified options Assumptions Invoked options