Bugfix: ASSIGNED variables are not considered for Localizer

- previously only RANGE and GLOBAL variables were considered
  for localiser pass
- exclude STATE variables as they are not usually a good
  candidate for such optimisations

src/visitors/defuse_analyze_visitor.cpp

@@ -422,10 +422,13 @@ DUChain DefUseAnalyzeVisitor::analyze(const ast::Ast& node, const std::string& n
     visiting_lhs = false;
     current_symtab = global_symtab;
     unsupported_node = false;
+
+    // variable types that we try to localise: RANGE, GLOBAL and ASSIGNED
+    auto global_symbol_properties = NmodlType::global_var | NmodlType::range_var |
+                                    NmodlType::assigned_definition;
     auto global_symbol = global_symtab->lookup_in_scope(variable_name);
     // If global_symbol exists in the global_symtab then search for a global variable. Otherwise the
     // variable can only be local if it exists
-    auto global_symbol_properties = NmodlType::global_var | NmodlType::range_var;
     if (global_symbol != nullptr && global_symbol->has_any_property(global_symbol_properties)) {
         variable_type = DUVariableType::Global;
     } else {

src/visitors/localize_visitor.cpp

@@ -77,7 +77,8 @@ std::vector<std::string> LocalizeVisitor::variables_to_optimize() const {
                                      | NmodlType::nonspecific_cur_var
                                      | NmodlType::pointer_var
                                      | NmodlType::bbcore_pointer_var
-                                     | NmodlType::electrode_cur_var;
+                                     | NmodlType::electrode_cur_var
+                                     | NmodlType::state_var;
 
     const NmodlType global_var_properties = NmodlType::range_var
                                      | NmodlType::assigned_definition
@@ -112,13 +113,18 @@ void LocalizeVisitor::visit_program(const ast::Program& node) {
         const auto& blocks = node.get_blocks();
         std::map<DUState, std::vector<std::shared_ptr<ast::Node>>> block_usage;
 
+        logger->debug("LocalizeVisitor: Checking DU chains for {}", varname);
+
         /// compute def use chains
         for (const auto& block: blocks) {
             if (node_for_def_use_analysis(*block)) {
                 DefUseAnalyzeVisitor v(*program_symtab, ignore_verbatim);
                 const auto& usages = v.analyze(*block, varname);
                 auto result = usages.eval();
                 block_usage[result].push_back(block);
+                logger->debug("\tDU chain in block {} is {}",
+                              block->get_node_type_name(),
+                              usages.to_string());
             }
         }
 

test/unit/visitor/defuse_analyze.cpp

@@ -445,6 +445,36 @@ SCENARIO("Perform DefUse analysis on NMODL constructs") {
         }
     }
 
+    GIVEN("Simple check of assigned variables") {
+        const std::string nmodl_text = R"(
+            NEURON {
+                GLOBAL x
+            }
+
+            ASSIGNED {
+                y
+            }
+
+            DERIVATIVE states {
+                x = 1
+                y = x
+                y = y + 2
+            }
+        )";
+
+        const std::string expected_text_y =
+            R"({"DerivativeBlock":[{"name":"D"},{"name":"U"},{"name":"D"}]})";
+
+        THEN("assigned variables are correctly analyzed") {
+            const std::string input = reindent_text(nmodl_text);
+            // Assigned variable "y" should be DU as it's defined and used as well
+            const auto& chains_y = run_defuse_visitor(input, "y");
+            REQUIRE(chains_y[0].to_string() == expected_text_y);
+            REQUIRE(chains_y[0].eval() == DUState::D);
+        }
+    }
+
+
     GIVEN("global variable definition in if-else block") {
         std::string nmodl_text = R"(
             NEURON {