for review: stack dumps.

[Zoltan Somogyi]

> > Here's a comparison.
> > I have trouble believing the figures myself.
> > 
> > Size:
> > without stack traces:
> > -rwx------   1 trd      mercury  5046272 Mar  4 19:38 mercury_compile*
> > with stack traces:
> > -rwx------   1 trd      mercury  17367040 Mar  5 11:17 mercury_compile*
> 
> Um, with a factor of 3 size increase, I'd argue this shouldn't be the
> default :-).

At the moment, we store a string giving the name of the label (and other info)
with every label that is a continuation point. Continuation points occur every
dozen or so instructions. Due to our label name construction algorithm, the
label names are very long, so I guess that a doubling of size comes from this
alone.

We can do much better. We can store the name of the procedure just once,
and make the labels in the procedure just give the label number as an int.
We can even go further, and separate out the module name, and store that
just once (via llds_common). And of course there is no need to ever store
the mercury__ prefix on all labels.

I am in the process of rewriting the continuation label part of the compiler
to make available variable information at internal trace points. I will take
the above into consideration.

Zoltan.