[PATCH] Remove all ggc'd bitmaps from PRE (Was Re: Memory overhead of tree-SSA optimization passes)

[Daniel Berlin]

On Sat, 2004-09-04 at 23:51 +0200, Jan Hubicka wrote:
> > > For PRE we consume most of memory in bitmaps, I am just testing patch
> > > obstackeizing them that should actually help here reducing GGC garbage
> > > to 40MB but still I don't follow why we need such an extreme amount of
> > > bitmaps.
> > 
> > Here's a patch that removes all ggc'd bitmaps from PRE.
> > 
> > It's bootstrapping now (on a day old tree).
> > If all goes well, i'll rebootstrap and testwhen the tree isn't broken,
> > add a changelog, and commit it.
> > 
> > However, in any case, it should be usable for your measurement purposes.
> > 
> Actually I am using the attached patch.  It reduces the memory footprint
> by 10% as one would expect that is good by itself I think.  I am waiting
> for numbers form automated tester but unless bootstrap unbreaks we won't
> get them before monday as I am just about leave for one day.
> 
> Is your patch actually able to re-use the bitmaps during the PRE
> process?  
Yes, but probably not even that obstack'ing them isn't a win.