[mlir][transform] Dump match failures in TrackingListener

mlir/include/mlir/Dialect/Transform/IR/TransformOps.h

 protected:
   /// Return a replacement payload op for the given op, which is going to be
   /// replaced with the given values. By default, if all values are defined by
   /// the same newly-created op, which also has the same type as the given op,
   /// that defining op is used as a replacement.
   virtual Operation *findReplacementOp(Operation *op,
                                        ValueRange newValues) const;
 
+  /// Notify the listener that the pattern failed to match the given operation,
+  /// and provide a callback to populate a diagnostic with the reason why the
+  /// failure occurred.
+  LogicalResult
+  notifyMatchFailure(Location loc,
+                     function_ref<void(Diagnostic &)> reasonCallback) override;
+
   /// This function is called when a tracked payload op is dropped because no
   /// replacement op was found. Derived classes can implement this function for
   /// custom error handling.
   virtual void notifyPayloadReplacementNotFound(Operation *op,
                                                 ValueRange values) {}
 
   /// Return "true" if the given op is a new op.
   bool isNewOp(Operation *op) const;

mlir/lib/Dialect/Transform/IR/TransformOps.cpp

 
 bool transform::TrackingListener::isNewOp(Operation *op) const {
   auto it = newOps.find(op->getName());
   if (it == newOps.end())
     return false;
   return it->second.contains(op);
 }
 
+LogicalResult transform::TrackingListener::notifyMatchFailure(
+    Location loc, function_ref<void(Diagnostic &)> reasonCallback) {
+  LLVM_DEBUG({
+    Diagnostic diag(loc, DiagnosticSeverity::Remark);
+    reasonCallback(diag);
+    DBGS() << "Match Failure : " << diag.str() << "\n";
+  });
+  return failure();
+}
+
 void transform::TrackingListener::notifyOperationInserted(Operation *op) {
   newOps[op->getName()].insert(op);
 }
 
 void transform::TrackingListener::notifyOperationRemoved(Operation *op) {
   // TODO: Walk can be removed when D144193 has landed.
   op->walk([&](Operation *op) {
     // Keep set of new ops up-to-date.