Re: Designs for better debug info in GCC

[Mark Mitchell <mark at codesourcery dot com>]

David Edelsohn wrote:
>>>>>> Mark Mitchell writes:
> 
> Mark> I think we all agree that providing better debugging of optimized code
> Mark> is a priori a good thing.  So, as I see it, this thread is focused on
> Mark> what internal representation we might use for that.
> 
> 	Yes, it is a good thing, but not at any price.  Regardless of the
> representation and implementation, there is a cost.  This discussion
> should not start with the premise that better debugging of optimized code
> is better at any cost.

I agree.  You're right to state this explicitly, but I'd implicitly
expected that we'd do cost/benefit analysis on this feature, as we would
any other.

> Mark> I'd like to start by
> Mark> capturing the functional changes that we want to make to GCC's debug
> Mark> output -- not the changes that we want in the debug experience, or
> Mark> changes that we need in GDB, but the changes in the generated DWARF.
> 
> 	Who is "we"?  What better debugging are GCC users demanding?  What
> debugging difficulties are they experiencing?  Who is that set of users?
> What functional changes would improve those cases?  What is the cost of
> those improvements in complexity, maintainability, compile time, object
> file size, GDB start-up time, etc.?

That's what I'm asking.  First and foremost, I want to know what,
concretely, Alexandre is trying to achieve, beyond "better debugging
info for optimized code".  Until we understand that, I don't see how we
can sensibly debate any methods of implementation, possible costs, etc.

-- 
Mark Mitchell
CodeSourcery
mark@codesourcery.com
(650) 331-3385 x713