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

Compiling and linking

Compiling with the f90 command

Chapter 266

system-wide default. This option applies only to executable files and shared libraries.

chatr(1) can be used to change this setting, including restoration of the default

setting, after the output file has been created.

+O[no]entrysched

+Oentrysched allows the optimizer to perform instruction scheduling on a

subprogram’s entry and exit code sequences. This option is only effective at

optimization level 1 or higher.

The option can change the behavior of programs that perform exception-handling or

that handle asynchronous interrupts.

The default is +Onoentrysched.

NOTE This option is valid only on the PA-RISC systems.

+O[no]failsafe

Enable [disable] failsafe optimization. When a compilation fails at the current

optimization level, +Ofailsafe will automatically restart the compilation at +O2 (for

specific high level optimizer errors +O3/+O4) or +O1 for Itanium processor family

architecture and +O0 for PA-RISC architecture.

The default is +Ofailsafe.

+Ofast

Select a combination of compilation options for optimum execution speed of the

compiled program. Those options include: +O2, +Olibcalls, +Onolimit,

+Ofltacc=relaxed, and +FPD. +Ofast also causes the +pi4M, +pd4M options to

be passed to the linker. In addition to these options, on the Itanium processor family

architecture, +DSnative instruction scheduling is selected and +mergeseg is also

passed to the linker.

+Ofaster

Selects the +Ofast option at optimization level +O3 for PA-RISC based architectures.

For Itanium processor family architectures, +Ofaster runs at +O4 and implies -ipo.

+O[no]fenvaccess

Inform the compiler that the program accesses [does not access] the floating point

environment to test flags or run under non-default modes. If it knows that a program

does not access the floating point environment, the compiler is allowed to perform

certain optimizations that it otherwise may not perform, such as global common

subexpression elimination, code motion, or constant folding.