This option instructs the compiler to perform optimizations to reduce image size at the expense of a possible increase in execution time.

Use this option if code size is more critical than performance. For example, when the -Ospace option is selected, large structure copies are done by out-of-line function calls instead of inline code.

If required, you can compile the time-critical parts of your code with -Otime, and the rest with -Ospace.