[llvm] [llvm][TableGen] Add a !initialized predicate to allow testing for ? (PR #117964)

[Krzysztof Drewniak via llvm-commits]

================
@@ -917,6 +917,13 @@ const Init *UnOpInit::Fold(const Record *CurRec, bool IsFinal) const {
       return NewInit;
     break;
 
+  case INITIALIZED:
+    if (isa_and_nonnull<UnsetInit>(LHS))
----------------
krzysz00 wrote:

On further inspection, yeah, this doesn't need a nullness check, fixed

https://github.com/llvm/llvm-project/pull/117964