On Wed, Aug 28, 2013 at 03:05:37PM +0200, Jakub Jelinek wrote:
> On Wed, Aug 28, 2013 at 02:57:01PM +0200, Marek Polacek wrote:
> > On Wed, Aug 28, 2013 at 02:49:54PM +0200, Richard Biener wrote:
> > > On Wed, Aug 28, 2013 at 2:15 PM, Marek Polacek <pola...@redhat.com> wrote:
> > > > On Wed, Aug 28, 2013 at 12:40:50PM +0200, Richard Biener wrote:
> > > >> On Tue, Aug 27, 2013 at 2:33 PM, Marek Polacek <pola...@redhat.com>
> > > >> wrote:
> > > >> > It turned out that for tree -> tree mapping we don't need the hash
> > > >> > table at all; pointer map is much more convenient. So this patch
> > > >> > weeds out the hash table out of ubsan and introduces pointer map
> > > >> > instead. Quite a lot of code could go away--no need to set the
> > > >> > alloc pools up etc.
> > > >> >
> > > >> > Regtested, ran bootstrap-ubsan on x86_64-linux. Applying to the
> > > >> > ubsan branch.
> > > >>
> > > >> You can use the type-safe pointer_map <tree> now (ok, only the data
> > > >> type
> > > >> is type safe, the pointer is still void).
> > > >
> > > > Thanks, done with the following. Please let me know if you see
> > > > something wrong in this; otherwise I'll commit it if the
> > > > bootstrap-ubsan passes.
> > >
> > > Probably misses freeing of the pointer-map using 'delete' somewhere.
> >
> > That's a problem, since ubsan is not a pass, we can't simply delete
> > the map at the end of the pass when it's not needed anymore...
> >
> > Perhaps some GTY(()) stuff could do it, but I don't know which one.
>
> You basically want to keep the pointer map for as long as you can
> lookup types, which is done now from both FEs and
> middle-end?
Yes, I think so.
> I guess it is the same category as say
> debug_expr_for_decl or value_expr_for_decl map tables, which we never free
> either. But for those we indeed
> GTY ((if_marked ("tree_decl_map_marked_p"), param_is (struct tree_decl_map)))
> and thus remove items if the original decl is not referenced from anywhere
> else; but pointer_map doesn't allow item removal; do we walk it for GC at
> all?
>From a quick look, it doesn't seem like we do. (I was searching for
something about pointer_map in ggc* and gen* files.)
> If so, it might prevent some types from being GC collected, on the
> other side right now it isn't expected that too many types will be put into
> the map.
That's right. I expect that typically there will be no more than,
say, 10 types in the map.
Marek
