Re: lto gimple types and debug info

[Kenneth Zadeck <zadeck at naturalbridge dot com>]

Mark Mitchell wrote:
> Kenneth Zadeck wrote:
>
> >   1) Screw the debugging.  The motivation behind this option is that
> >   not only is it easy, but the reality is that we have changed the
> >   program so much that even if we did "fix up the types" so that the
> >   matched the generated program, that the code is so different from
> >   what the user expected that (s)he could not even debug if anyway.
>
> I think this would be very disappointing to users.  One of the 
> long-standing advantages of GCC is that you can in fact do some level 
> of debugging with optimized code.
>
> It's true that if you tear apart structures, the debugger is going to 
> have a hard time dealing with that at present, but it's also true that 
> dropping all language-specific knowledge of types is going to make 
> life very hard for users.  And it's not like you're always going to 
> mangle things beyond recognition; tossing out all the debug info is 
> throwing out the baby with the bathwater.
>
> >   2) Generate the debugging for the types early, and then add an
> >   interface that would parse and regenerate the debugging info with
> >   the changes.  It is quite likely that this would lock gcc
> >   completely into dwarf, but that appears to only be a problem for
> >   AIX at this point, so that may not be that much of a problem.
>
> This is the approach I would suggest.  Dump out the debug info for 
> types before you throw away all the information, and then leave it aside.
I am coming to the conclusion, for other reasons that this is what we 
are going to have to do.

kenny