Re: When to emit C++ debug info?

[Daniel Berlin <dberlin at dberlin dot org>]

On Jan 3, 2004, at 8:36 PM, Geoff Keating wrote:

> > X-Original-To: geoffk@foam.wonderslug.com
> > Date: Sat, 3 Jan 2004 19:05:42 -0600 (CST)
> > From: Chris Lattner <sabre@nondot.org>
>
> > Geoff Keating writes:
> > > I think we'll want to be able to do it these ways:
> > > - One way where the minimal debugging information is emitted so that
> > >   when put together, the whole program has complete debugging
> > >   information; and
> > > - Another way where complete information is emitted for a single 
> > > file.
> > >
> > > I'm not sure why you'd want something between these two extremes.
> >
> > Why not always do #2, and have the linker eliminate the duplicate
> > information?
>
> Because it makes .o files large, and that makes the linker slow
> because it has to process the huge collection of .o files.

Okay, so keep a database of debug info for a given compilation, stored 
in an aside file, and use that to make sure you don't output debug info 
you've already outputted for other objects, to keep object file size 
down.
This should require no more or less of a make utility than PCH does.

You can't possibly know what's going to be in the other files before 
you see them, so a strategy " where the minimal debugging information 
is emitted so that when put together, the whole program has complete 
debugging information" just won't work well, unless you were planning 
on implementing it by knowing what you've already emitted elsewhere.
--Dan