[llvm] [UniformityAnalysis] Add CallbackVH tracking to keep UniformValues consistent on IR deletion (PR #187658)

[Nikita Popov via llvm-commits]

nikic wrote:

Ah yes, AssertingVH doesn't really work for analyses in the NewPM. The alternative that would work is PoisoningVH. But PoisoningVH will also only actually detect issues when pointers get reused.

https://github.com/llvm/llvm-project/pull/187658