[tree-ssa] Lazy updating of stmt operands

[Andrew MacLeod]

On Mon, 2003-12-15 at 18:36, law@redhat.com wrote:
> In message <1071323157.3257.138.camel@p4>, Andrew MacLeod writes:
>  >The Cache isnt something we're trying to work around. Thats there to
>  >prevent us from having to muck around in trees looking for things which
>  >are operands. The stmt is in the form of trees, our "cache" is the
>  >equivilent of your instruction. It consists of the operands plus looking
>  >at the tree code(s) of the stmt. 
>  >
>  >So we have 1 word for each operand. It points to the SSA_NAME in the
>  >stmt tree which represents that ssa version. 
>  >
>  >As far as Im concerned, we're not working around anything. Everything
>  >works just fine. IF someone wants/needs the def->use inforation, it can
>  >be built today. What we dont have is the ability to keep it up to date
>  >for some period of time, simply because we've never needed it. If the
>  >time comes that we do need it, it is not hard to add. 
> In fact, we could even ponder the idea of what we now know as the operand
> cache morphing into a lighter-weight IL at some point in the future.
> 
Indeed, it is the core of what we deal with.

Andrew