Re: dwarflint

[Roland McGrath <roland at redhat dot com>]

> Make a file that just has "int x;" in it, then compile with -g.
> GCC won't emit a .debug_aranges.

This was exactly the test I used (I even called it 'x' instead of 'foo' for
some reason!).  It emits low_pc..high_pc that is an empty range in .text
(but a relocated one, so after link it will wind up some specific
0x123,0x123 pair rather than zeros).  

It didn't occur to me last week to look for the .debug_aranges section.
But I concur that it should be consistent: .debug_aranges should be exactly
the set of ranges (whatever that is) emitted for any compile_unit DIE.
That should likewise resolve to whatever specific empty range it is, not
absolute zeros.  (I say so not because the relocated empty range seems
especially useful--it tells you nothing except what the link order of the
.o files happened to be--but just to stick to the aforementioned
consistency in a thorough way.)

> I think it ought to emit an empty one, see
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42288
> for the rationale.

I guess I concur with the rationale that each and every CU appearing in
some rhs in the .debug_aranges section helps identify the section as
complete.  Before considering that issue, I would have said that it was
questionable for a compile_unit to have the PC attributes at all when it
does not actually cover any PCs.  I'm still not 100% convinced.


Thanks,
Roland