[tree-ssa] AST optimizer in C++?

[Chris Lattner]

> > IMHO, the advantages of using SSA and having it available (for both
> > convenience, optimizer efficiency, and more powerful algorithms than data
> > flow can provide at times) greatly out-weigh the disadvantages of having
> > to update it.
>
> We already have it available, and used.
> Nobody is saying we shouldn't use SSA algorithms when possible, or convert
> algorithms to SSA.
> We aren't talking about whether to use SSA or not, we are talking about
> whether to keep it as annotations, or encode it into the IR.
> Please address the benefits of *that*, not of SSA in general.

See: http://gcc.gnu.org/ml/gcc/2002-08/msg01658.html

> > What kinds of transformations do you have in mind that would be
> > inconvenient to implement in SSA form?
>
> That's not quite relevant.
> The real question is:
> What does encoding it directly into the IR, rather than doing is as we do
> now, buy us, that makes it worth it, given the disadvantages?

Ditto.

-Chris

http://llvm.cs.uiuc.edu/
http://www.nondot.org/~sabre/Projects/