[llvm] [DenseMap] Replace tombstone deletion with TAOCP 6.4 Algorithm R (PR #200595)

[Aiden Grossman via llvm-commits]

boomanaiden154 wrote:

> Mind running your internal TAP Global Presubmit with https://github.com/llvm/llvm-project/pull/200540 and https://github.com/llvm/llvm-project/pull/200595 applied? Just want to make sure we're in the clear before landing the stacked DenseMap cleanups

Now that everything is merged, I think I'll just wait for things to go through the integrate/release process. I don't think I'll be able to start a TGP any more quickly. I'm working on some tooling that would automate the process, but haven't gotten it finished yet.

https://github.com/llvm/llvm-project/pull/200595