Re: Designs for better debug info in GCC

[Alexandre Oliva <aoliva@redhat.com>]

On Dec 18, 2007, Robert Dewar <dewar@adacore.com> wrote:

> Alexandre Oliva wrote:
>> On Dec 18, 2007, Robert Dewar <dewar@adacore.com> wrote:

>>> OK, so you are agreeing that good debuggability is impossible
>>> with all the optimizations in place, so once again, let's have
>>> an optimziation level that optimizes as far as possible without
>>> harming debuggability.

>> It's just that changing optimizations is precisely *against* the goals
>> of my current project.  So, don't expect significant efforts to this
>> end from me at this time.

> But you can't achieve the above criterion with your approach.

Actually, you can.  My approach is about ensuring the mapping between
the location of source and implementation variables is correct.  This
is orthogonal to how much optimization you make.

If you optimize more, more values or locations may become unavailable,
but this is not about correctness (what fraction of the annotations
point at locations that hold the correct value), and it's not even
about completeness (what fraction of the source variables are
represented at all locations they are available), it's just about
theoretical completeness (what fraction of the source variables are
represented at all locations they would be available without
optimization).

-- 
Alexandre Oliva         http://www.lsd.ic.unicamp.br/~oliva/
FSF Latin America Board Member         http://www.fsfla.org/
Red Hat Compiler Engineer   aoliva@{redhat.com, gcc.gnu.org}
Free Software Evangelist  oliva@{lsd.ic.unicamp.br, gnu.org}