[Relay] Port param dict save/load from NNVM

[weberlo]

This PR addresses #2413 by porting the nnvm.compiler.save_param_dict and nnvm.compiler.load_param_dict functions to Relay as tvm.relay.save_param_dict and tvm.relay.load_param_dict, respectively.

To serialize NDArrays, we wrap them in TensorValues, which have serialization functions defined on them. Let me know of any concerns about this approach.

While porting, I found that ClosureNode, TupleValueNode, and TensorValueNode were not registered with TVM_REGISTER_NODE_TYPE. This PR also addresses this issue.

The test_bigendian_rpc_param test has not yet been confirmed to pass, so I still need to wait for the results from CI.

@jroesch @tqchen @srkreddy1238

Apologies for being late on this one. Let me know of anyone else I should @.

[weberlo]

test_bigendian_rpc_param seems to be passing, when it shouldn't be.

I think this path

host = os.environ.get("TVM_POWERPC_TEST_HOST", None)
port = os.environ.get("TVM_POWERPC_TEST_PORT", 9090)
if host is None:
    return

is still being taken.

[tqchen]

@weberlo we should use the original function that actually saves the ndarray dict(as in NNVMv1), otherwise the binary format won't be readable by graph_runtime.load_params

[weberlo]

@tqchen Do you mean these functions? If all of the tests are passing without using those functions, does that mean we need a new test?

[tqchen]

Yes, I do mean these functions. A more general test is to use these save_dict function and then call graphruntime.load_params to load them in.

[tqchen]

@weberlo please update the PR

[weberlo]

@tqchen I'm having some weird problems with includes. Maybe my approach is wrong, but I'm trying to take the functions from nnvm/src/compiler/graph_runtime.cc and put them in src/runtime/graph/graph_runtime.cc. These functions require the following node to be defined in the header:

/*!
 * \brief wrapper node container for exchange.
 */
struct NDArrayWrapperNode : public ::tvm::Node {
  std::string name;
  tvm::runtime::NDArray array;

  void VisitAttrs(tvm::AttrVisitor* v) final {
    v->Visit("name", &name);
    v->Visit("array", &array);
  }

  static constexpr const char* _type_key = "NDArrayWrapper";
  TVM_DECLARE_NODE_TYPE_INFO(NDArrayWrapperNode, Node);
};

TVM_DEFINE_NODE_REF(NDArrayWrapper, NDArrayWrapperNode);

. But when I try to put #include <tvm/node/node.h> in the header, it says it can't find that header.

Is there a different header I should be including, or is this struct definition using outdated types?

[weberlo]

@tqchen: @jroesch suggested to move the functions to a new set of files src/relay/backend/param_dict.[h/cc]. Any objections?

[tqchen]

that works you can move the nnvm impl there, and use the new exposed packfubc

[tqchen]

change the example code to relay

[tqchen]

@weberlo some final comments