[MLIR] Clear SubGraph construction info (#3559)

* Don't hold to shared pointers after sub-graph extraction pass is done

* style

src/contrib/mlir/compiler/pass/mlir_subgraph_extraction.cpp

@@ -132,6 +132,7 @@ bool MLIRSubgraphExtractionPass::run_on_function(std::shared_ptr<Function> func)
     sanity_check(func, ck_nodes);
 #endif
 
+    clean_up();
     return true;
 }
 
@@ -506,6 +507,12 @@ bool MLIRSubgraphExtractionPass::check_cycles(std::shared_ptr<Node> node,
     return false;
 }
 
+void MLIRSubgraphExtractionPass::clean_up()
+{
+    m_id_to_graph.clear();
+    m_node_to_graph.clear();
+}
+
 const std::set<std::type_index> MLIRSubgraphExtractionPass::m_supported_ops{
 #define MLIR_OP(OP) TI(ngraph::op::OP),
 #include "contrib/mlir/compiler/ops_supported.inc"

src/contrib/mlir/compiler/pass/mlir_subgraph_extraction.hpp

@@ -127,6 +127,7 @@ namespace ngraph
             NodeVector build_ck_nodes(std::shared_ptr<Function> func);
 
             void sanity_check(std::shared_ptr<Function> func, NodeVector& ck_nodes);
+            void clean_up();
 
         private:
             using IDGraphMap = std::unordered_map<int, MLIRSubgraph>;