ISPC codegen compatibility fixes (#105)

This PR covers numerous fixes in the ISPC (and C) code generators working around many of real-world corner cases, which had been missed (or postponed) before:

* Fallback to C when VERBATIM nodes are found in AST
* Allow AstLookupVisitor::lookup to be called without a type
* Uses an additional instance of CodegenCVisistor that is constructed
  inside the ispc code generator as a fallback code generator.
* Removed the whole-file VERBATIM fallback in the main function.
* added missing constants
* filtered kernel routines, which contain verbatim blocks
* emit uncalled procedures and functions in C wrapper
* don't emit `printf` debug code
* rename PI into ISPC_PI to avoid name clashes with ispc constant
* emit functions that use tables in C
* Make sure that global data is shared between wrapper and ispc target
* Exclude Eigen node types from ISPC backend

This closes #83

src/codegen/codegen_c_visitor.cpp

@@ -1949,9 +1949,9 @@ std::string CodegenCVisitor::process_shadow_update_statement(ShadowUseStatement&
 void CodegenCVisitor::print_nmodl_constant() {
     printer->add_newline(2);
     printer->add_line("/** constants used in nmodl */");
-    printer->add_line("static double FARADAY = 96485.3;");
-    printer->add_line("static double PI = 3.14159;");
-    printer->add_line("static double R = 8.3145;");
+    printer->add_line("static const double FARADAY = 96485.3;");
+    printer->add_line("static const double PI = 3.14159;");
+    printer->add_line("static const double R = 8.3145;");
 }
 
 
@@ -2323,7 +2323,7 @@ void CodegenCVisitor::print_coreneuron_includes() {
  * Note that static variables are already initialized to 0. We do the
  * same for some variables to keep same code as neuron.
  */
-void CodegenCVisitor::print_mechanism_global_var_structure() {
+void CodegenCVisitor::print_mechanism_global_var_structure(bool wrapper) {
     auto float_type = default_float_data_type();
     printer->add_newline(2);
     printer->add_line("/** all global variables */");
@@ -3796,6 +3796,7 @@ void CodegenCVisitor::visit_solution_expression(SolutionExpression* node) {
     }
 }
 
+
 /****************************************************************************************/
 /*                                Print nrn_state routine                                */
 /****************************************************************************************/
@@ -4107,7 +4108,12 @@ void CodegenCVisitor::print_wrapper_routines() {
 }
 
 
-void CodegenCVisitor::visit_program(Program* node) {
+void CodegenCVisitor::set_codegen_global_variables(std::vector<SymbolType>& global_vars) {
+    codegen_global_variables = global_vars;
+}
+
+
+void CodegenCVisitor::setup(Program* node) {
     program_symtab = node->get_symbol_table();
 
     CodegenHelperVisitor v;
@@ -4124,6 +4130,11 @@ void CodegenCVisitor::visit_program(Program* node) {
 
     update_index_semantics();
     rename_function_arguments();
+}
+
+
+void CodegenCVisitor::visit_program(Program* node) {
+    setup(node);
     print_codegen_routines();
     print_wrapper_routines();
 }

src/codegen/codegen_c_visitor.hpp

@@ -47,7 +47,10 @@ enum class BlockType {
     State,
 
     /// watch block
-    Watch
+    Watch,
+
+    /// net_receive block
+    NetReceive
 };
 
 
@@ -561,7 +564,7 @@ class CodegenCVisitor: public AstVisitor {
 
 
     /// nmodl constants
-    void print_nmodl_constant();
+    virtual void print_nmodl_constant();
 
 
     /// top header printed in generated code
@@ -613,7 +616,7 @@ class CodegenCVisitor: public AstVisitor {
 
 
     /// structure that wraps all global variables in the mod file
-    virtual void print_mechanism_global_var_structure();
+    virtual void print_mechanism_global_var_structure(bool wrapper = false);
 
 
     /// structure that wraps all range and int variables required for mod file
@@ -764,26 +767,10 @@ class CodegenCVisitor: public AstVisitor {
     void print_function_prototypes();
 
 
-    /// print check_function() for function/procedure using table
-    void print_table_check_function(ast::Block* node);
-
-
-    /// print replacement function for function/procedure using table
-    void print_table_replacement_function(ast::Block* node);
-
-
     /// print check_table functions
     void print_check_table_thread_function();
 
 
-    /// nmodl function definition
-    void print_function(ast::FunctionBlock* node);
-
-
-    /// nmodl procedure definition
-    void print_procedure(ast::ProcedureBlock* node);
-
-
     /// print nmodl function or procedure (common code)
     void print_function_or_procedure(ast::Block* node, std::string& name);
 
@@ -832,14 +819,6 @@ class CodegenCVisitor: public AstVisitor {
     virtual void print_net_receive_loop_end();
 
 
-    /// kernel for buffering net_receive events
-    void print_net_receive_buffering(bool need_mech_inst = true);
-
-
-    /// net_receive kernel function definition
-    void print_net_receive_kernel();
-
-
     /// net_receive function definition
     void print_net_receive();
 
@@ -901,18 +880,6 @@ class CodegenCVisitor: public AstVisitor {
     virtual void print_global_function_common_code(BlockType type);
 
 
-    /// nrn_init function definition
-    void print_nrn_init(bool skip_init_check = true);
-
-
-    /// nrn_state / state update function definition
-    void print_nrn_state();
-
-
-    /// nrn_cur / current update function definition
-    void print_nrn_cur();
-
-
     /// mechanism registration function
     void print_mechanism_register();
 
@@ -921,10 +888,6 @@ class CodegenCVisitor: public AstVisitor {
     void print_watch_activate();
 
 
-    /// print watch activate function
-    void print_watch_check();
-
-
     /// all includes
     virtual void print_headers_include();
 
@@ -994,6 +957,66 @@ class CodegenCVisitor: public AstVisitor {
         , layout(layout)
         , float_type(float_type) {}
 
+
+    CodegenCVisitor(std::string mod_filename,
+                    LayoutType layout,
+                    std::string float_type,
+                    std::shared_ptr<CodePrinter>& target_printer)
+        : target_printer(target_printer)
+        , printer(target_printer)
+        , mod_filename(mod_filename)
+        , layout(layout)
+        , float_type(float_type) {}
+
+
+    /// nrn_init function definition
+    void print_nrn_init(bool skip_init_check = true);
+
+
+    /// nrn_state / state update function definition
+    void print_nrn_state();
+
+
+    /// nrn_cur / current update function definition
+    void print_nrn_cur();
+
+
+    /// kernel for buffering net_receive events
+    void print_net_receive_buffering(bool need_mech_inst = true);
+
+
+    /// net_receive kernel function definition
+    void print_net_receive_kernel();
+
+
+    /// print watch activate function
+    void print_watch_check();
+
+
+    /// print check_function() for function/procedure using table
+    void print_table_check_function(ast::Block* node);
+
+
+    /// print replacement function for function/procedure using table
+    void print_table_replacement_function(ast::Block* node);
+
+
+    /// nmodl function definition
+    void print_function(ast::FunctionBlock* node);
+
+
+    /// nmodl procedure definition
+    virtual void print_procedure(ast::ProcedureBlock* node);
+
+
+    /** setup the Codgen, typically called from within visit_program but may be called from
+     *  specialized targets to setup this Code generator as fallback.
+     */
+    void setup(ast::Program* node);
+
+    void set_codegen_global_variables(std::vector<SymbolType>& global_vars);
+
+
     virtual void visit_binary_expression(ast::BinaryExpression* node) override;
     virtual void visit_binary_operator(ast::BinaryOperator* node) override;
     virtual void visit_boolean(ast::Boolean* node) override;

src/codegen/codegen_helper_visitor.cpp

@@ -14,6 +14,7 @@
 #include "visitors/rename_visitor.hpp"
 
 #include <fmt/format.h>
+#include <set>
 
 using namespace fmt::literals;
 
@@ -121,6 +122,15 @@ void CodegenHelperVisitor::find_ion_variables() {
             }
         }
     }
+
+    /// check if worte_conc(...) will be needed
+    for (const auto& ion: info.ions) {
+        for (const auto& var: ion.writes) {
+            if (!ion.is_ionic_current(var) && !ion.is_rev_potential(var)) {
+                info.require_wrote_conc = true;
+            }
+        }
+    }
 }
 
 

src/codegen/codegen_info.hpp

@@ -371,7 +371,10 @@ struct CodegenInfo {
 
     /// true if EigenNewtonSolver is used in nrn_state block
     bool nrn_state_has_eigen_solver_block() const;
+
+    /// if we need a call back to wrote_conc in neuron/coreneuron
+    bool require_wrote_conc = false;
 };
 
 }  // namespace codegen
-}  // namespace nmodl
+}  // namespace nmodl