150 meg of varrays (was Re: [tree-ssa PATCH] Pick memory consumptionlow hanging fruit)

[Daniel Berlin <dberlin at dberlin dot org>]

>
> We must have 150 meg of varrays (which are ggc_allocated) and random
> garbage associated with expressions.


And wonder of wonders, we apparently have 150 meg of varray garbage from
resizing and clearing these things.

I just changed the varrays to be not gc allocated, and the stat goes from

Total Overhead:                         160164822
Total Allocated:                        950183384

to

Total Overhead:                          93248390
Total Allocated:                        808418892

Let me remove one of the unnecessary varrays (the erefs ones that we
store with each block is strictly unnecessary now) i've been meaning to
get rid of, and see if we can do even better.

In the meanwhile, i think my brain is going to explode trying to think of
why this generates 70 meg of overhead.

--Dan