[llvm-dev] Manipulating DAGs in TableGen

[Paul C. Anagnostopoulos via llvm-dev]

I was wondering today whether the TableGen DAG support would be more useful if you could manipulate DAGs a little more easily. Right now, you can:

* Specify a DAG with (...)

* Catenate DAGs with !con().

* Construct a DAG with !dag().

* Iterate over a DAG with !foreach().

* Get and set the DAG operator with !getop() and !setop().

What if you could also get and set a DAG's operands individually, by position or by $xxx name? Would that add enough power/convenience that you would build more interesting DAGs in TableGen, or is it just easier to do such building in the backends?