Depending on the compiled sources, each Compiler optimization may have its advantages or disadvantages. The following are recommended:
The default configuration enables most optimizations in the Compiler. If they cause problems in your code (e.g., they make the code hard to debug), switch them off (these options usually have the -On prefix). Candidates for such optimizations are peephole optimizations.
Some optimizations may produce more code for some functions than for others (e.g., -Oi: Inlining or -Cu: Loop Unrolling). Try those options to get the best result for each.
To acquire the best results for each function, compile each module with the -OdocF: Dynamic Option Configuration for Functions option. An example for this option is -OdocF="-Or".
For compilers with the ICG optimization engine, the following option combination provides the best results:
-Ona -OdocF="-Onca|-One|-Or"