Re: GCC 3.5 Status (2004-08-29)

[Jan Hubicka <hubicka@ucw.cz>]

> On Monday 30 August 2004 02:53, Mark Mitchell wrote:
> > >Hmm, let's argue.  So you think 25-100% slowdown is justifyable despite
> > >just about every project using GCC complaining about how GCC gets slower
> > >with each release?
> >
> > Obviously, this is not ideal.  However, we have few practical
> > alternatives.  I am not convinced that any further delay will get us
> > better results.  I do not see a broad committment to improving
> > compile-time speed when optimizing: in fact, I got zero proposals from
> > people planning to work specifically on that issue.
> 
> It is funny that you say here that you got zero proposals, yet you
> had a section in your mail:
> > -------------------------
> > Compile-Time Improvements
> > -------------------------
> > 
> > There were three submissions relating primarily to compile-time
> 
> Also, I believe the edge-vector-branch work is also purely a speedup
> project - it will make looking up PHI arguments much faster.  As I
> have shown before on this mailing list, this is one of the major bottle
> necks for passes like DOM.
> 
> Merging the LNO ivopts is another pass that could help win back speed
> because it would allow us to kill the old loop optimizer (ie. loop.c 
> and unroll.c) and all the yuckie-ness that it causes, like
> reconstructing the CFG, recomputing dominance, recomputing loop info,
> etc. etc.  All of that is expensive, and removing expensive things is
> a good thing...
> 
> Anyway, you are probably right that there appear to be few people
> working *specifically* on speeding up the compiler.  But many people
> work on replacing expensive RTL optimizations with cheaper tree ones.

Also there are are certainly people (at least me ;) who seriously hope
to do some work before the code is frozen, but merging existing work is
a priority.  So I wrote only the tasks for whose I have something ready
with hope that I will also manage to figure out how to kill some of
perofmrance/memory problems on the way too.  I think number of these can
go to stage3 anyway.

Honza