'foo' debug type
$ opt < a.bc > /dev/null -mypass -debug-only=bar
'bar' debug type
+ $ opt < a.bc > /dev/null -mypass -debug-only=foo,bar
+ 'foo' debug type
+ 'bar' debug type
Of course, in practice, you should only set ``DEBUG_TYPE`` at the top of a file,
to specify the debug type for the entire module. Be careful that you only do
use the same string, they will all be turned on when the name is specified.
This allows, for example, all debug information for instruction scheduling to be
enabled with ``-debug-only=InstrSched``, even if the source lives in multiple
-files.
+files. The name must not include a comma (,) as that is used to seperate the
+arguments of the ``-debug-only`` option.
For performance reasons, -debug-only is not available in optimized build
(``--enable-optimized``) of LLVM.