This switch enables optimization. It can have the following possible values:
- Switches on optimizations, corresponding to level 2 optimizations.
- Switches of all kinds of optimizations.
- Returns to default (i.e. command-line or config file) specified optimizations.
- Parses the string and switches on the optimizations found in the string as if they were
passed using the -Oo command line option. The optimizations must be separated by
The following strings are supported:
- Use register variables.
- Use uncertain optimizations.
- Optimize for size.
- Skip stackframes.
- Peephole optimizations.
- Use common subexpression elimination at the assembler level.
- Unroll loops
- change tail recursion to regular while
- Reorder fields if this results in better alignment.
- Fast math operations
- remove calls to empty procedures.
- Use common subexpression elimination
- Use DFA (Data Flow Analysis).
You can disable a certain optimization by prefixing the value with NO.
is equivalent to
Multiple optimizations can be specified with:
Dusable loop unrolling with:
This switch is also activated by the -Ooxxx command line switch. Note the small ’o’: it is -Oo
followed by the switch name.