[mlir] Add symbol user attribute interface.

Enables verification of attributes, independent of op, that references symbols.

RFC: this enables verifying Attribute with symbol usage indpendent of
operation attached to (e.g., the validity is on the Attribute
independent of the operation).

Author: jpienaar

mlir/include/mlir/IR/CMakeLists.txt

@@ -1,4 +1,7 @@
 add_mlir_interface(SymbolInterfaces)
+set(LLVM_TARGET_DEFINITIONS SymbolInterfaces.td)
+mlir_tablegen(SymbolInterfacesAttrInterface.h.inc -gen-attr-interface-decls)
+mlir_tablegen(SymbolInterfacesAttrInterface.cpp.inc -gen-attr-interface-defs)
 add_mlir_interface(RegionKindInterface)
 
 set(LLVM_TARGET_DEFINITIONS OpAsmInterface.td)

mlir/include/mlir/IR/SymbolInterfaces.td

@@ -220,6 +220,24 @@ def SymbolUserOpInterface : OpInterface<"SymbolUserOpInterface"> {
   ];
 }
 
+def SymbolUserAttrInterface : AttrInterface<"SymbolUserAttrInterface"> {
+  let description = [{
+    This interface describes an attrivute 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.
+  }];
+  let cppNamespace = "::mlir";
+
+  let methods = [
+    InterfaceMethod<"Verify the symbol uses held by this attribute of this operation.",
+      "::llvm::LogicalResult", "verifySymbolUses",
+      (ins "::mlir::Operation *":$op,
+           "::mlir::SymbolTableCollection &":$symbolTable)
+    >,
+  ];
+}
+
 //===----------------------------------------------------------------------===//
 // Symbol Traits
 //===----------------------------------------------------------------------===//

mlir/include/mlir/IR/SymbolTable.h

@@ -499,5 +499,6 @@ ParseResult parseOptionalVisibilityKeyword(OpAsmParser &parser,
 
 /// Include the generated symbol interfaces.
 #include "mlir/IR/SymbolInterfaces.h.inc"
+#include "mlir/IR/SymbolInterfacesAttrInterface.h.inc"
 
 #endif // MLIR_IR_SYMBOLTABLE_H

mlir/lib/IR/SymbolTable.cpp

@@ -511,7 +511,14 @@ LogicalResult detail::verifySymbolTable(Operation *op) {
   SymbolTableCollection symbolTable;
   auto verifySymbolUserFn = [&](Operation *op) -> std::optional<WalkResult> {
     if (SymbolUserOpInterface user = dyn_cast<SymbolUserOpInterface>(op))
-      return WalkResult(user.verifySymbolUses(symbolTable));
+      if (failed(user.verifySymbolUses(symbolTable)))
+        return WalkResult::interrupt();
+    for (auto &attr : op->getRawDictionaryAttrs()) {
+      if (auto user = dyn_cast<SymbolUserAttrInterface>(attr.getValue())) {
+        if (failed(user.verifySymbolUses(op, symbolTable)))
+          return WalkResult::interrupt();
+      }
+    }
     return WalkResult::advance();
   };
 
@@ -1132,3 +1139,4 @@ ParseResult impl::parseOptionalVisibilityKeyword(OpAsmParser &parser,
 
 /// Include the generated symbol interfaces.
 #include "mlir/IR/SymbolInterfaces.cpp.inc"
+#include "mlir/IR/SymbolInterfacesAttrInterface.cpp.inc"

utils/bazel/llvm-project-overlay/mlir/BUILD.bazel

@@ -82,6 +82,8 @@ exports_files(glob(["include/**/*.td"]))
         tbl_outs = {
             "include/mlir/IR/" + name + ".h.inc": ["-gen-op-interface-decls"],
             "include/mlir/IR/" + name + ".cpp.inc": ["-gen-op-interface-defs"],
+            "include/mlir/IR/" + name + "AttrInterface.h.inc": ["-gen-attr-interface-decls"],
+            "include/mlir/IR/" + name + "AttrInterface.cpp.inc": ["-gen-attr-interface-defs"],
         },
         tblgen = ":mlir-tblgen",
         td_file = "include/mlir/IR/" + name + ".td",