Enable the GCC dump for the rustc using GCC backend (#3109)
Enable the GCC dump for the rustc using GCC backend (#3109)

Beware that the way it is working causes several dump files to be empty. The
list of potential files is based on `-fdump-passes` output, but during the
actual compilation, some passes may or may not emit something (eg. a passe may
not be executed at all because it's not applicable). The drop down list will
contain some dump names that will simply display message like:

   Pass 'cselim (tree)' was requested
   but nothing was dumped. Possible causes are:
    - pass is not valid in this (maybe you changed the compiler options);
    - pass is valid but did not emit anything (eg. it was not executed).

This is expected and until someone has a better idea, this will be the case :)

fixes: #2868
Signed-off-by: Marc Poulhiès <3159a46716b78b3b6c7634a90e9d5898d5f4255e@kataplop.net>
mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer