[llvm] Add the 'initialized' attribute langref and support (PR #84803)

[Jan Voung via llvm-commits]

================
@@ -2044,6 +2052,19 @@ void Verifier::verifyParameterAttrs(AttributeSet Attrs, Type *Ty,
     Check(Ty->isIntOrIntVectorTy(CR.getBitWidth()),
           "Range bit width must match type bit width!", V);
   }
+  if (Attrs.hasAttribute(Attribute::Initialized)) {
+    auto Inits = Attrs.getAttribute(Attribute::Initialized).getValueAsRanges();
+    Check(!Inits.empty(), "Attribute 'initialized' does not support empty list",
+          V);
+
+    for (size_t i = 1; i < Inits.size(); i++) {
----------------
jvoung wrote:

perhaps check low < high for the same "i"?

https://github.com/llvm/llvm-project/pull/84803