[Dwarf-discuss] Re: dwarf2 question

[Nettleton, Brian]

I remember that we came across one compiler that didn't have the
abbreviations in order.  I think it was the Arm Ltd. compiler.

-Brian Nettleton
Wind River Systems
 

> -----Original Message-----
> From: dwarf-discuss-bounces at base3.freestandards.org 
> [mailto:dwarf-discuss-bounces at base3.freestandards.org] On 
> Behalf Of Mathieu Lacage
> Sent: Wednesday, March 02, 2005 11:19 PM
> To: Michael Eager
> Cc: dwarf
> Subject: [Dwarf-discuss] Re: dwarf2 question
> 
> On Wed, 2005-03-02 at 08:50 -0800, Michael Eager wrote:
> > Mathieu Lacage wrote:
> > > hi michael,
> > > 
> > > I am not sure this question would be apropriate to the 
> dwarf mailing
> > > list so I thought I could ask you and well, hope for the best :)
> > > 
> > > I wonder whether it is safe to assume that the 
> abbreviation code of an
> > > abbreviation declaration is strictly increasing over a 
> compilation unit.
> > > (see section 7.5.3 of the dwarf2 spec). i.e.: I wonder whether the
> > > abbreviation code of the abbreviation declaration is 
> necessarily higher
> > > than the abbreviation code of the current declaration. 
> > > 
> > > If this was the case, then it would be sort of nice 
> because it would be
> > > possible not to start from the beginning of the array of 
> abbreviation
> > > declarations or to stop before the end of the array if 
> you already know
> > > the location of a few abbreviation declarations...
> > 
> > I think this would be a reasonable question for the mailing list.
> 
> Ok, I will try it next time.
> 
> > There is no ordering specified in the spec, so I can't say that it
> > is safe to assume that abbrevitions are in ascending order.  On the
> > other hand, I believe most compilers write the abbrev section from
> > a fixed list, which would (most likely) be in order.
> > 
> > The design of the abbrev section allows a compiler to dynamically
> > generate abbreviations, which might not be in order.
> > 
> > Given that the abbrev table has variable length entries, most
> > compilers would read the table into memory and create an index
> > so that one could quickly find the desired abbrev entry.  That way
> > the question of whether the entries are in order becomes moot.
> 
> Yes, I am trying to write a parser which uses a minimum 
> amount of memory
> but which is reasonably efficient.
> 
> I guess I can assume they are in ascending order since at least the
> tables generated by gcc seem to be in ascending order and if I cannot
> find what I am looking for, I can easily revert to simply parsing the
> whole table. Of course, this will be probably less efficient 
> if they are
> never in order but well...
> 
> thank you for your answer,
> Mathieu
> -- 
> 
> 
> _______________________________________________
> Dwarf-discuss mailing list
> Dwarf-discuss at mail.freestandards.org
> http://mail.freestandards.org/mailman/listinfo/dwarf-discuss
>