bertpass_gpu.cc does not support MXNet 1.8

[leezu]

Due to API change apache/mxnet#19135

[samskalicky]

Thanks @leezu. The custom pass in https://github.com/dmlc/gluon-nlp/blob/v0.10.x/scripts/bert/bertpass_gpu.cc uses some custom code that @MoisesHer and I worked on post-1.7.0 release that eventually became the default in 1.8.0. Thanks to this collaboration, in 1.8 all lines 30-248 have been integration into lib_api.h so they can be removed from bertpass_gpu.cc.

Plus, we eliminated the extra step of taking the symbol_json string and converting it to a graph object in

gluon-nlp/scripts/bert/bertpass_gpu.cc

Lines 251 to 262 in 3fbe961

	MXReturnValue custom_pass(const std::string& in_graph, const std::string** out_graph,
	const std::unordered_map<std::string, std::string>& options,
	const std::unordered_map<std::string, MXTensor>& args,
	const std::unordered_map<std::string, MXTensor>& aux,
	const PassResource& res) {
	for (auto kv : options)
	std::cout << "option: " << kv.first << " ==> " << kv.second << std::endl;
	//convert graph from JSON string to Graph/Node data structure
	Graph g = Graph::fromString(in_graph);
	//g.print();

So now the API will be simplified to:
https://github.com/apache/incubator-mxnet/blob/cc4b8ec68b6ec9dae73046e9c34ac97439efda83/example/extensions/lib_pass/pass_lib.cc#L34-L35

MXReturnValue myPass(mxnet::ext::Graph *g,
                     const std::unordered_map<std::string, std::string>& options) {

So little things like changing how you loop over the nodes in the graph from:

gluon-nlp/scripts/bert/bertpass_gpu.cc

Line 266 in 3fbe961

for(Node* n : g.nodes){

will need to be changed to: https://github.com/apache/incubator-mxnet/blob/cc4b8ec68b6ec9dae73046e9c34ac97439efda83/example/extensions/lib_subgraph/subgraph_lib.cc#L308-L309

  for(int i=0; i<graph->size(); i++) {
    mxnet::ext::Node* n = graph->getNode(i);

And creating new nodes from:

gluon-nlp/scripts/bert/bertpass_gpu.cc

Line 280 in 3fbe961

Node* node_expand_1_bias = new Node();

to:
https://github.com/apache/incubator-mxnet/blob/cc4b8ec68b6ec9dae73046e9c34ac97439efda83/example/extensions/lib_subgraph/subgraph_lib.cc#L315

Node* input = graph->addNode(n->name + "_input", "null");

Mostly just little things like this. But this should be a lot of change for the better.

[leezu]

I think it would be ideal to use preprocessor #if to have bertpass_gpu.cc support both MX 1.7 and 1.8

[MoisesHer]

I think it would be ideal to use preprocessor #if to have bertpass_gpu.cc support both MX 1.7 and 1.8

thanks for checking this. I will make the modifications as suggested to support both MXNet 1.7 & 1.8