Reload patch to improve 386 code

[Jeffrey A Law]

  In message < 199809060428.VAA02085@smtp.earthlink.net >you write:
  > I don't see why the base address tracking code should have to do
  > anything.  My plan was just to use different alias sets for each spill
  > register (we have 2^32 of them, after all!).  If you like, you could
  > reuse these from function to function, so the maximum number of alias
  > sets used up this was would be the number of spills in any one
  > function.  My guess is that if that gets close to 4 billion, we have
  > worse problems.
  > 
  > I'd be happy (delighted, even) to implement this, but I'd like a test
  > case that someone things will benefit.  (I am in *no* way doubting the
  > existence of such a thing, but having one would allow me to verify my
  > work.) 
Just seemed easier to have a single alias set for spills.  I'm not
particularly partial to either solution.  They should both work.

As for a testcase.  Who knows.  I would think it would be reasonably
straightforward to build one.

ANy benefit right now would be in sched2 and possibly reload_cse since
we don't have generalized spill code motion yet.

Presumably we'd need a loop and something in the loop needs to be
spilled to the stack and we need unrelated memory accesses throuh a
pointer which we know nothing about.

jeff