[llvm] [AMDGPU] Flatten recursive register resource info propagation (PR #142766)

[Jay Foad via llvm-commits]

jayfoad wrote:

> Could we instead do a little constant propagation dataflow over the call graph? It should require less duplicated effort, and we should get the optimal propagation through the whole graph all in one go.

Or find strongly connected components of the callgraph and run on one SCC at a time? (Maybe that is just a slightly different way to implement the same thing.)

https://github.com/llvm/llvm-project/pull/142766