Add explicit SparseTensor support to SignatureDef.

PiperOrigin-RevId: 157860466

tensorflow/core/protobuf/meta_graph.proto

@@ -202,8 +202,34 @@ message CollectionDef {
 
 // Information about a Tensor necessary for feeding or retrieval.
 message TensorInfo {
-  string name = 1;
+  // For sparse tensors, The COO encoding stores a triple of values, indices,
+  // and shape.
+  message CooSparse {
+    // The shape of the values Tensor is [?].  Its dtype must be the dtype of
+    // the SparseTensor as a whole, given in the enclosing TensorInfo.
+    string values_tensor_name = 1;
+
+    // The indices Tensor must have dtype int64 and shape [?, ?].
+    string indices_tensor_name = 2;
+
+    // The dynamic logical shape represented by the SparseTensor is recorded in
+    // the Tensor referenced here.  It must have dtype int64 and shape [?].
+    string dense_shape_tensor_name = 3;
+  }
+
+  oneof encoding {
+    // For dense `Tensor`s, the name of the tensor in the graph.
+    string name = 1;
+    // There are many possible encodings of sparse matrices
+    // (https://en.wikipedia.org/wiki/Sparse_matrix).  Currently, TensorFlow
+    // uses only the COO encoding.  This is supported and documented in the
+    // SparseTensor Python class.
+    CooSparse coo_sparse = 4;
+  }
   DataType dtype = 2;
+  // The static shape should be recorded here, to the extent that it can
+  // be known in advance.  In the case of a SparseTensor, this field describes
+  // the logical shape of the represented tensor (aka dense_shape).
   TensorShapeProto tensor_shape = 3;
 }
 

tensorflow/tools/api/golden/tensorflow.-tensor-info.-coo-sparse.pbtxt

+path: "tensorflow.TensorInfo.CooSparse"
+tf_class {
+  is_instance: "<class \'tensorflow.core.protobuf.meta_graph_pb2.CooSparse\'>"
+  is_instance: "<type \'google.protobuf.pyext._message.CMessage\'>"
+  member {
+    name: "DENSE_SHAPE_TENSOR_NAME_FIELD_NUMBER"
+    mtype: "<type \'int\'>"
+  }
+  member {
+    name: "DESCRIPTOR"
+    mtype: "<type \'google.protobuf.pyext._message.MessageDescriptor\'>"
+  }
+  member {
+    name: "Extensions"
+    mtype: "<type \'getset_descriptor\'>"
+  }
+  member {
+    name: "INDICES_TENSOR_NAME_FIELD_NUMBER"
+    mtype: "<type \'int\'>"
+  }
+  member {
+    name: "VALUES_TENSOR_NAME_FIELD_NUMBER"
+    mtype: "<type \'int\'>"
+  }
+  member_method {
+    name: "ByteSize"
+  }
+  member_method {
+    name: "Clear"
+  }
+  member_method {
+    name: "ClearExtension"
+  }
+  member_method {
+    name: "ClearField"
+  }
+  member_method {
+    name: "CopyFrom"
+  }
+  member_method {
+    name: "DiscardUnknownFields"
+  }
+  member_method {
+    name: "FindInitializationErrors"
+  }
+  member_method {
+    name: "FromString"
+  }
+  member_method {
+    name: "HasExtension"
+  }
+  member_method {
+    name: "HasField"
+  }
+  member_method {
+    name: "IsInitialized"
+  }
+  member_method {
+    name: "ListFields"
+  }
+  member_method {
+    name: "MergeFrom"
+  }
+  member_method {
+    name: "MergeFromString"
+  }
+  member_method {
+    name: "ParseFromString"
+  }
+  member_method {
+    name: "RegisterExtension"
+  }
+  member_method {
+    name: "SerializePartialToString"
+  }
+  member_method {
+    name: "SerializeToString"
+  }
+  member_method {
+    name: "SetInParent"
+  }
+  member_method {
+    name: "WhichOneof"
+  }
+  member_method {
+    name: "__init__"
+  }
+}

tensorflow/tools/api/golden/tensorflow.-tensor-info.pbtxt

@@ -2,6 +2,14 @@ path: "tensorflow.TensorInfo"
 tf_class {
   is_instance: "<class \'tensorflow.core.protobuf.meta_graph_pb2.TensorInfo\'>"
   is_instance: "<type \'google.protobuf.pyext._message.CMessage\'>"
+  member {
+    name: "COO_SPARSE_FIELD_NUMBER"
+    mtype: "<type \'int\'>"
+  }
+  member {
+    name: "CooSparse"
+    mtype: "<class \'google.protobuf.pyext.cpp_message.GeneratedProtocolMessageType\'>"
+  }
   member {
     name: "DESCRIPTOR"
     mtype: "<type \'google.protobuf.pyext._message.MessageDescriptor\'>"