cinn_compiler add RemoveIdentity pass after Decomposer, test=develop (#37738)

paddle/fluid/framework/paddle2cinn/cinn_compiler.cc

@@ -193,6 +193,8 @@ std::unique_ptr<CinnCompiledObject> CinnCompiler::CompileGraph(
   CinnGraphSymbolization symbol{compiled_num, graph, target, input_tensors};
   auto frontend_program = symbol();
   ProgramPass::Apply(&frontend_program, target, {"Decomposer"});
+  auto fetch_ids = symbol.GetFetchIds();
+  ::cinn::frontend::ApplyPass(&frontend_program, fetch_ids, "RemoveIdentity");
   auto cinn_graph = std::make_shared<::cinn::hlir::framework::Graph>(
       frontend_program, target);
   VLOG(1) << "-- The " << compiled_num << "-th compilation ("
@@ -201,7 +203,6 @@ std::unique_ptr<CinnCompiledObject> CinnCompiler::CompileGraph(
   ApplyPass(cinn_graph.get(), "OpFusion");
   auto scope = BuildScope(target, cinn_graph);
 
-  auto fetch_ids = symbol.GetFetchIds();
   VLOG(4) << "All fetch var ids in CINN: "
           << string::join_strings(fetch_ids, ',');