[llvm] [TableGen] Refactor Intrinsics record (PR #106986)

[Matt Arsenault via llvm-commits]

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@@ -273,11 +273,12 @@ using TypeSigTy = SmallVector<unsigned char>;
 /// Computes type signature of the intrinsic \p Int.
 static TypeSigTy ComputeTypeSignature(const CodeGenIntrinsic &Int) {
   TypeSigTy TypeSig;
-  if (const auto *R = Int.TheDef->getValue("TypeSig")) {
-    for (const auto *a : cast<ListInit>(R->getValue())->getValues()) {
-      for (const auto *b : cast<ListInit>(a)->getValues())
-        TypeSig.emplace_back(cast<IntInit>(b)->getValue());
-    }
+  const Record *TypeInfo = Int.TheDef->getValueAsDef("TypeInfo");
+  const ListInit *OuterList = TypeInfo->getValueAsListInit("TypeSig");
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arsenm wrote:

Yes, but tablegen shouldn't be crashy garbage on arbitrary inputs. If it's not literally baked into the code, and is input data like the predefined .td files, it needs to be verified 

https://github.com/llvm/llvm-project/pull/106986