Add support for calling system functions as a task (SystemVerilog)

This patch adds the ability to call a system function as a task for
the SystemVerilog generation (-g2009). The return value is really
calculated, but it is ignored.

compiler.h

@@ -212,4 +212,11 @@ extern const struct sfunc_return_type* lookup_sys_func(const char*name);
 extern int load_sys_func_table(const char*path);
 extern void cleanup_sys_func_table();
 
+/*
+ * In system Verilog it is allowed with a warning to call a function
+ * as a task. You can even cast the return value away and have no
+ * warning message.
+ */
+extern ivl_sfunc_as_task_t def_sfunc_as_task;
+
 #endif

elaborate.cc

@@ -2697,7 +2697,8 @@ NetProc* PCallTask::elaborate_sys(Design*des, NetScope*scope) const
 	    return noop;
       }
 
-      NetSTask*cur = new NetSTask(peek_tail_name(path_), eparms);
+      NetSTask*cur = new NetSTask(peek_tail_name(path_), def_sfunc_as_task,
+                                  eparms);
       cur->set_line(*this);
       return cur;
 }

ivl.def

@@ -250,6 +250,7 @@ ivl_stmt_nevent
 ivl_stmt_parm
 ivl_stmt_parm_count
 ivl_stmt_rval
+ivl_stmt_sfunc_as_task
 ivl_stmt_sub_stmt
 
 ivl_switch_a

ivl_target.h

@@ -388,6 +388,13 @@ typedef enum ivl_statement_type_e {
       IVL_ST_WHILE   = 23
 } ivl_statement_type_t;
 
+/* SystemVerilog allows a system function to be called as a task. */
+typedef enum ivl_sfunc_as_task_e {
+      IVL_SFUNC_AS_TASK_ERROR   = 0,
+      IVL_SFUNC_AS_TASK_WARNING = 1,
+      IVL_SFUNC_AS_TASK_IGNORE  = 2
+} ivl_sfunc_as_task_t;
+
 /* This is the type of a variable, and also used as the type for an
    expression. */
 typedef enum ivl_variable_type_e {
@@ -1995,6 +2002,8 @@ extern unsigned ivl_stmt_parm_count(ivl_statement_t net);
   /* IVL_ST_ASSIGN IVL_ST_ASSIGN_NB IVL_ST_CASSIGN IVL_ST_CONTRIB
      IVL_ST_FORCE */
 extern ivl_expr_t ivl_stmt_rval(ivl_statement_t net);
+  /* IVL_ST_STASK */
+extern ivl_sfunc_as_task_t ivl_stmt_sfunc_as_task(ivl_statement_t net);
   /* IVL_ST_DELAY, IVL_ST_DELAYX, IVL_ST_FOREVER, IVL_ST_REPEAT
      IVL_ST_WAIT, IVL_ST_WHILE */
 extern ivl_statement_t ivl_stmt_sub_stmt(ivl_statement_t net);

main.cc

@@ -106,6 +106,13 @@ bool gn_io_range_error_flag = true;
 bool gn_strict_ca_eval_flag = false;
 bool gn_verilog_ams_flag = false;
 
+/*
+ * For some generations we allow a system function to be called
+ * as a task and only print a warning message. The default for
+ * this is that it is a run time error.
+ */
+ivl_sfunc_as_task_t def_sfunc_as_task = IVL_SFUNC_AS_TASK_ERROR;
+
 map<string,const char*> flags;
 char*vpi_module_list = 0;
 
@@ -1011,6 +1018,12 @@ int main(int argc, char*argv[])
 	    cout << "ELABORATING DESIGN" << endl;
       }
 
+	/* Decide if we are going to allow system functions to be called
+	 * as tasks. */
+      if (generation_flag >= GN_VER2009) {
+	    def_sfunc_as_task = IVL_SFUNC_AS_TASK_WARNING;
+      }
+
 	/* On with the process of elaborating the module. */
       Design*des = elaborate(roots);
 

netlist.cc

@@ -1932,8 +1932,9 @@ const NetNet* NetFuncDef::return_sig() const
       return result_sig_;
 }
 
-NetSTask::NetSTask(const char*na, const svector<NetExpr*>&pa)
-: name_(0), parms_(pa)
+NetSTask::NetSTask(const char*na, ivl_sfunc_as_task_t sfat,
+                   const svector<NetExpr*>&pa)
+: name_(0), sfunc_as_task_(sfat), parms_(pa)
 {
       name_ = lex_strings.add(na);
       assert(name_[0] == '$');
@@ -1952,6 +1953,11 @@ const char*NetSTask::name() const
       return name_;
 }
 
+ivl_sfunc_as_task_t NetSTask::sfunc_as_task() const
+{
+      return sfunc_as_task_;
+}
+
 unsigned NetSTask::nparms() const
 {
       return parms_.count();

netlist.h

@@ -2969,10 +2969,12 @@ class NetRelease : public NetAssignBase {
 class NetSTask  : public NetProc {
 
     public:
-      NetSTask(const char*na, const svector<NetExpr*>&);
+      NetSTask(const char*na, ivl_sfunc_as_task_t sfat,
+               const svector<NetExpr*>&);
       ~NetSTask();
 
       const char* name() const;
+      ivl_sfunc_as_task_t sfunc_as_task() const;
 
       unsigned nparms() const;
 
@@ -2985,6 +2987,7 @@ class NetSTask  : public NetProc {
 
     private:
       const char* name_;
+      ivl_sfunc_as_task_t sfunc_as_task_;
       svector<NetExpr*>parms_;
 };
 

t-dll-api.cc

@@ -2385,6 +2385,18 @@ extern "C" ivl_expr_t ivl_stmt_rval(ivl_statement_t net)
       return 0;
 }
 
+extern "C" ivl_sfunc_as_task_t ivl_stmt_sfunc_as_task(ivl_statement_t net)
+{
+      switch (net->type_) {
+	  case IVL_ST_STASK:
+	    return net->u_.stask_.sfunc_as_task_;
+	  default:
+	    assert(0);
+      }
+
+      return IVL_SFUNC_AS_TASK_ERROR;
+}
+
 extern "C" ivl_statement_t ivl_stmt_sub_stmt(ivl_statement_t net)
 {
       switch (net->type_) {

t-dll-proc.cc

@@ -688,6 +688,7 @@ void dll_target::proc_stask(const NetSTask*net)
       stmt_cur_->type_ = IVL_ST_STASK;
 	/* System task names are lex_strings strings. */
       stmt_cur_->u_.stask_.name_ = net->name();
+      stmt_cur_->u_.stask_.sfunc_as_task_ = net->sfunc_as_task();
       stmt_cur_->u_.stask_.nparm_= nparms;
       stmt_cur_->u_.stask_.parms_= (ivl_expr_t*)
 	    calloc(nparms, sizeof(ivl_expr_t));

t-dll.h

@@ -753,6 +753,7 @@ struct ivl_statement_s {
 
 	    struct { /* IVL_ST_STASK */
 		  const char*name_;
+		  ivl_sfunc_as_task_t sfunc_as_task_;
 		  unsigned   nparm_;
 		  ivl_expr_t*parms_;
 	    } stask_;

tgt-vvp/draw_vpi.c

@@ -386,11 +386,32 @@ static void draw_vpi_taskfunc_args(const char*call_string,
 
 void draw_vpi_task_call(ivl_statement_t tnet)
 {
-      char call_string[1024];
-      sprintf(call_string, "    %%vpi_call %u %u \"%s\"",
-              ivl_file_table_index(ivl_stmt_file(tnet)),
-              ivl_stmt_lineno(tnet), ivl_stmt_name(tnet));
-      draw_vpi_taskfunc_args(call_string, tnet, 0);
+      unsigned parm_count = ivl_stmt_parm_count(tnet);
+      const char *command = "error";
+
+      switch (ivl_stmt_sfunc_as_task(tnet)) {
+	  case IVL_SFUNC_AS_TASK_ERROR:
+	    command = "%vpi_call";
+	    break;
+	  case IVL_SFUNC_AS_TASK_WARNING:
+	    command = "%vpi_call/w";
+	    break;
+	  case IVL_SFUNC_AS_TASK_IGNORE:
+	    command = "%vpi_call/i";
+	    break;
+      }
+
+      if (parm_count == 0) {
+            fprintf(vvp_out, "    %s %u %u \"%s\";\n", command,
+                    ivl_file_table_index(ivl_stmt_file(tnet)),
+                    ivl_stmt_lineno(tnet), ivl_stmt_name(tnet));
+      } else {
+	    char call_string[1024];
+	    sprintf(call_string, "    %s %u %u \"%s\"", command,
+	            ivl_file_table_index(ivl_stmt_file(tnet)),
+	            ivl_stmt_lineno(tnet), ivl_stmt_name(tnet));
+	    draw_vpi_taskfunc_args(call_string, tnet, 0);
+      }
 }
 
 struct vector_info draw_vpi_func_call(ivl_expr_t fnet, unsigned wid)

tgt-vvp/vvp_process.c

@@ -1824,16 +1824,6 @@ static int show_stmt_while(ivl_statement_t net, ivl_scope_t sscope)
 
 static int show_system_task_call(ivl_statement_t net)
 {
-      unsigned parm_count = ivl_stmt_parm_count(net);
-
-      if (parm_count == 0) {
-	    fprintf(vvp_out, "    %%vpi_call %u %u \"%s\";\n",
-	            ivl_file_table_index(ivl_stmt_file(net)),
-	            ivl_stmt_lineno(net), ivl_stmt_name(net));
-	    clear_expression_lookaside();
-	    return 0;
-      }
-
       draw_vpi_task_call(net);
 
 	/* VPI calls can manipulate anything, so clear the expression