[llvm] (Draft) [SimplifyIndVar] Push more users to worklist for simplifyUsers (PR #93598)

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

Two potential problems with this approach:

- Some places might implicitly assume IV users are inside the loop.
- I'm a bit concerned about compile-time.  If you recursively visit every value derived from the exit value of the loop, you can easily end up with quadratic compile-time growth: if you have N successive loops, you visit instructions in the last loop N^2 times.

CC @fhahn

https://github.com/llvm/llvm-project/pull/93598