You can also use any specialized optimization switches supported by
the back end being used. These switches have not been extensively
tested with GNAT but can generally be expected to work. Examples of
switches in this category for the GCC back end are
-funroll-loops and the various target-specific -m
options (in particular, it has been observed that -march=xxx
can significantly improve performance on appropriate machines). For
full details of these switches, see the ‘Submodel Options’ section in
the ‘Hardware Models and Configurations’ chapter of Using the GNU Compiler Collection (GCC).