[llvm] [MemDep] Mark deps as `Dirty` on translation failure as opposed to `Unknown` (PR #125741)

[via llvm-commits]

goldsteinn wrote:

> It looks like this has significant compile-time impact: https://llvm-compile-time-tracker.com/compare.php?from=223989cc09dab8b524649d67f0521659fd15cfec&to=501bcc5b49202d9a7b1c0ada55d13be993b29f38&stat=instructions:u
> 
> Presumably that's why unknown is used here.

Hmm, although part of that is useful work that was artificially blocked before.

Maybe I'll try this only on the first iteration, see if we can get the positives without the cost.

Any other ideas on how to do this?

https://github.com/llvm/llvm-project/pull/125741