[mlir] Properly handle NativeCodeCallVoid in result patterns.

[jcai19]

Summary

Currently NativeCodeCallVoid is not supported in the result patterns.
For example, below code will fail to build with the error message
referencing unbound symbol.

def Foo: NativeCodeCallVoid<"foo()">;

def AddToAddV2 : Pattern<
  (TF_AddOp TF_NumberTensor:$arg0, TF_NumberTensor:$arg1),
  [(TF_AddV2Op $arg0, $arg1), (Foo)]>;

MLIR tablegen-based pattern rewrites does not preserve attributes of the source
op, with this change users could mannualy copy source attributes to the target
op via NativeCodeCallVoid. This is a replacement of D157032.

[jcai19]

Pull request created at https://github.com/llvm/llvm-project/pull/65804 per the new policy.

mlir/tools/mlir-tblgen/RewriterGen.cpp

if (numExpectedResults == 0) {
     os << "rewriter.eraseOp(op0);\n";
   } else {
     // Process replacement result patterns.
     os << "::llvm::SmallVector<::mlir::Value, 4> tblgen_repl_values;\n";
     for (int i = replStartIndex; i < numResultPatterns; ++i) {
       DagNode resultTree = pattern.getResultPattern(i);
       auto val = handleResultPattern(resultTree, offsets[i], 0);
       os << "\n";
+      if (resultTree.isNativeCodeCall() &&
+          resultTree.getNumReturnsOfNativeCode() == 0) {
+        os << val << ";\n";
+      } else {
         // Resolve each symbol for all range use so that we can loop over them.
         // We need an explicit cast to `SmallVector` to capture the cases where
         // `{0}` resolves to an `Operation::result_range` as well as cases that
         // are not iterable (e.g. vector that gets wrapped in additional braces by
         // RewriterGen).
         // TODO: Revisit the need for materializing a vector.
         os << symbolInfoMap.getAllRangeUse(
             val,
             "for (auto v: ::llvm::SmallVector<::mlir::Value, 4>{ {0} }) {{\n"
             "  tblgen_repl_values.push_back(v);\n}\n",
             "\n");
       }
+    }
     os << "\nrewriter.replaceOp(op0, tblgen_repl_values);\n";
   }
 
   // Process supplemtal patterns.
   int numSupplementalPatterns = pattern.getNumSupplementalPatterns();
   for (int i = 0, offset = -numSupplementalPatterns;
        i < numSupplementalPatterns; ++i) {
     DagNode resultTree = pattern.getSupplementalPattern(i);