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

[Jan Voung via llvm-commits]

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@@ -222,6 +241,40 @@ class ConstantRangeAttributeImpl : public EnumAttributeImpl {
   ConstantRange getConstantRangeValue() const { return CR; }
 };
 
+class ConstantRangeListAttributeImpl final
+    : public EnumAttributeImpl,
+      private TrailingObjects<ConstantRangeListAttributeImpl, ConstantRange> {
+  friend TrailingObjects;
+
+  unsigned ValSize;
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jvoung wrote:

nit: maybe just "Size" since there isn't a field named "Val"

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