[Mesa-dev] [PATCH 1/3] glsl: add ir_partial_visitor

[Luca Barbieri]

Well, the alternative is to copy&paste this into ir_lower_jumps and
other similar passes.

I added a new class instead of changing ir_visitor so that subclasses
that need to examine all leaves will get a compile error if not
updated when new leaves are introduced. This is debatable though,
since you need to add the function to ir_visitor anyway.