User's Guide

+O[no]aggressive

The +Oaggressive option enables aggressive optimizations. The +Onoaggressive option

disables aggressive optimizations.

By default, aggressive optimizations are turned off. The +Oaggressive option is approximately

equivalent to +Osignedpointers +Onoinitcheck +Ofltacc=relaxed.

NOTE: This option is deprecated and may not be supported in future releases. Instead you can

use +Ofastoption.

+O[no]limit

The +Olimit option enables optimizations that significantly increase compile time or that consume

a lot of memory.

The +Onolimit option suppresses optimizations regardless of their effect on compile time or

memory consumption.

Use +Onolimit at all optimization levels.

Usage:

+O[no]limit=level

The defined values of level are:

default Based on tuning heuristics, the optimizer will spend a reasonable amount of time

processing large procedures. This is the default option.

min For large procedures, the optimizer will avoid non-linear time optimizations. This

option is a synonym for +Olimit.

none The optimizer will fully optimize large procedures, possibly resulting in significantly

increased compile time. This option is a synonym for +Onolimit.

Example:

To remove optimization time restrictions at O2, O3, or O4 optimization levels, use +Onolimit as

follows:

aCC <opt level> +Onolimit sourcefile.C

+O[no]ptrs_to_globals[=list]

The +O[no]ptrs_to_globals option tells the optimizer whether global variables are accessed

[are not accessed] through pointers. If +Onoptrs_to_globals is specified, it is assumed that

statically-allocated data (including file-scoped globals, file-scoped statics, and function-scoped

statics) will not be read or written through pointers. The default is +Onoptrs_to_globals.

+O[no]size

While most optimizations reduce code size, the +Osize option suppresses those few optimizations

that significantly increase code size. The +Onosize option enables code-expanding optimizations.

Use +Osize at all optimization levels. The default is +Onosize.

Advanced +Ooptimization Options

Advanced optimization options provide additional control for special situations.

Code Optimizing Options 57