[llvm] [RemoveDIs][DebugInfo] Add DPValue checks to the verifier, prepare DPValue for parsing support (PR #79810)

[Jeremy Morse via llvm-commits]

https://github.com/jmorse approved this pull request.

LGTM,

> I've got this done now, but just a question for you since you added it - currently this check is a hard error in the verifier, should we change it now to a debug info error instead?

I'm not sure -- I'd say that for any situation where the debug-info is totally broken and we can only ever expect to crash, there should be a hard error. "Break hard, break fast" gets us better detection of problems instead of having them present later.

For situations where the debug-info isn't correct, but in a way that makes it meaningless / stupid / unreliable rather than causing a crash, those should be debug-info dropping errors. (I think you've done fine at picking between the two!).

https://github.com/llvm/llvm-project/pull/79810