[tree-ssa] Dominator opts fixes and enhancements

[Diego Novillo]

On Mon, 2003-08-25 at 09:27, Andrew MacLeod wrote:

> So if a variable had a real
> definition, and that got deleted or changed, the var would have no
> definition, and the annotation would *not* have a default defintion
> listed right? So we can tell that it is in error that it doesn't have a
> definition... 
> 
Sorry, I can't parse the above :)

The default definition is *only* created if, while renaming the code
into SSA, the very first reference we find of a variable is a USE or a
VUSE.  In that case, if the variable had a default definition assigned
to it already, we just use it, otherwise we create a new one.  So,
default definitions are always artificial and cannot be removed by any
optimization.


> Also, this new symbol expose of partial ranges isnt going to result in
> potential virtual/real use mixes is it?
> 
Nope.  I keep meaning to add a test for this in tree_verify_flow_info.


Diego.