[mlir][tensor] Add a tiling interface registration for pack/unpack only.

[mravishankar]

Yeah, this is fine by me.

mlir/include/mlir/Dialect/Tensor/IR/TensorTilingInterfaceImpl.h

 Operation *bubbleUpPadSlice(OpBuilder &b, tensor::PadOp padOp,
                             ArrayRef<OpFoldResult> offsets,
                             ArrayRef<OpFoldResult> sizes,
                             bool generateZeroSliceGuard = true);
 
 /// Registers external models for Tiling interface for tensor ops.
 /// Currently, it registers:
 ///
-/// * TilingInterface for `tensor.pad`.
+/// * TilingInterface for `tensor.pad`, `tensor.pack`, and `tensor.unpack`.
 ///
 /// Unfortunately, a "normal" internal registration is not possible at the
 /// moment, because of the dependency of the interface implementation for these
 /// ops on `affine.apply` and Affine dialect already depends on TensorOps. In
 /// order to break the cyclic dependency (TensorOps->AffineOps->TensorOps) the
 /// implementation is moved to a separate library.
 void registerTilingInterfaceExternalModels(mlir::DialectRegistry &registry);
 
+/// Similar to the above registeration, but it is only for `tensor.pack` and
+/// `tensor.unpack` ops.
+void registerTilingInterfaceExternalModelsForPackUnPackOps(
+    DialectRegistry &registry);
+
 } // namespace tensor
 } // namespace mlir
 
 #endif // MLIR_DIALECT_TENSOR_IR_TENSORTILINGINTERFACEIMPL_H_

mlir/lib/Dialect/Tensor/IR/TensorTilingInterfaceImpl.cpp

 void mlir::tensor::registerTilingInterfaceExternalModels(
     DialectRegistry &registry) {
   registry.addExtension(+[](MLIRContext *ctx, TensorDialect *dialect) {
     tensor::PadOp::attachInterface<PadOpTiling>(*ctx);
     tensor::PackOp::attachInterface<PackOpTiling>(*ctx);
     tensor::UnPackOp::attachInterface<UnPackOpTiling>(*ctx);
   });
 }
+
+void mlir::tensor::registerTilingInterfaceExternalModelsForPackUnPackOps(
+    DialectRegistry &registry) {
+  registry.addExtension(+[](MLIRContext *ctx, TensorDialect *dialect) {
+    tensor::PackOp::attachInterface<PackOpTiling>(*ctx);
+    tensor::UnPackOp::attachInterface<UnPackOpTiling>(*ctx);
+  });
+}