Re: [sa]: Revert partial def stuff, use fake variables instead

[Daniel Berlin <dberlin at dberlin dot org>]

> this is basically what I do now.  The problematic case is if you turn a[i]
> into *newiv_1.  Then we have to get tags for the newiv_1 pointer, which
> is problematic (see the discussion following
> http://gcc.gnu.org/ml/gcc-patches/2004-09/msg01897.html for details).

If you have turned a non-pointer access into a pointer access, then you 
*have* to either rerun alias analysis, or create name/type tags with the 
approriate aliases (if you know them).

We don't currently verify that you don't create duplicate type/name tags 
(ie tags with the same variables pointed to)
but they actually aren't allowed, which makes your job more complicated.

It may be easiest to just have an external interface for creating tags 
with a known points-to set, and taking care of all the magic 
involved inside tree-ssa-alias, which knows how to do this stuff right.


--Dan