[tree-ssa] Maintaining/representing def-use/use-def information

[Daniel Berlin]

On Dec 15, 2003, at 4:14 PM, Zdenek Dvorak wrote:

> Hello,
>
>> No, we don't.  We don't have any concept of "defining variable" or
>> "versions" at all.  Though all SSA construction papers talk about 
>> building
>> versions of source variables, once you start doing transformations, 
>> that
>> idea becomes quickly meaningless.
>
> except for ssa-pre, that requires the original variable names.

Uh, only to determine lexical equivalence of expressions.

> I still
> consider it an indication that there is something rotten with the
> optimization, but did not get the idea how to make it better so far.
>

Give me value numbers, and it'll do it based on value numbers.

>