[llvm] [mlir] [EquivalenceClasses] Use DenseMap instead of std::set. (NFC) (PR #134264)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

It also possible to use a single SetVector, although it requires some more indirections and is quite a bit more code: https://github.com/llvm/llvm-project/commit/a683c91d9a63e22443a8905f83ef7139fbaf6c6d

Not sure if there's a better/easier way to do things



https://github.com/llvm/llvm-project/pull/134264