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

[Krzysztof Drewniak via llvm-commits]

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@@ -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))
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krzysz00 wrote:

I recall  some of the surrounding code being careful about NULLs, so ... seemed worth doing

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