[llvm] [llvm] Replace unordered_{map,set} with Dense{Map,Set}/SmallPtrSet (PR #202222)

[Alexis Engelke via llvm-commits]

https://github.com/aengelke commented:

LGTM otherwise. But it looks like the SPIRV back-end is not really following our data structure recommendations anyway...

Again, I'm unsure about the value of this unless there is agreement to completely ban std::unordered_{map,set}. Outside of maybe SPIRV, none of these changes parts should be performance-critical.

Please wait for another few days in case SPIRV maintainers have comments.

https://github.com/llvm/llvm-project/pull/202222