[llvm] [mlir] [mlir] Add symbol user attribute interface. (PR #153206)

[Jacques Pienaar via llvm-commits]

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@@ -220,6 +220,24 @@ def SymbolUserOpInterface : OpInterface<"SymbolUserOpInterface"> {
   ];
 }
 
+def SymbolUserAttrInterface : AttrInterface<"SymbolUserAttrInterface"> {
+  let description = [{
+    This interface describes an attribute that may use a `Symbol`. This
+    interface allows for users of symbols to hook into verification and other
+    symbol related utilities that are either costly or otherwise disallowed
+    within a traditional operation.
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jpienaar wrote:

This is mostly copied from line 206. Costly here is symbol table users construction (if done per op to verify usage vs per symbol scope one ends up walking the same module O(number of ops) rather than O(symbol tables)), and disallowed is checking for symbols in peer scope. I can add these.

https://github.com/llvm/llvm-project/pull/153206