Added hierarchy -auto-top

diff --git a/passes/hierarchy/hierarchy.cc b/passes/hierarchy/hierarchy.cc
index 40fc9ae995c57f1f5b8d9b92d60b476144ce045e..155d4e4637bd11a3fa334ed17e38b41c1adacc60 100644 (file)
--- a/passes/hierarchy/hierarchy.cc
+++ b/passes/hierarchy/hierarchy.cc
@@ -321,6 +321,17 @@ bool set_keep_assert(std::map<RTLIL::Module*, bool> &cache, RTLIL::Module *mod)
        return cache[mod];
 }
 
+int find_top_mod_score(Design *design, Module *module, dict<Module*, int> &db)
+{
+       if (db.count(module) == 0) {
+               db[module] = 0;
+               for (auto cell : module->cells())
+                       if (design->module(cell->type))
+                               db[module] = std::max(db[module], find_top_mod_score(design, design->module(cell->type), db) + 1);
+       }
+       return db.at(module);
+}
+
 struct HierarchyPass : public Pass {
        HierarchyPass() : Pass("hierarchy", "check, expand and clean up design hierarchy") { }
        virtual void help()
@@ -365,6 +376,9 @@ struct HierarchyPass : public Pass {
                log("        specified top module. otherwise a module with the 'top' attribute set\n");
                log("        will implicitly be used as top module, if such a module exists.\n");
                log("\n");
+               log("    -auto-top\n");
+               log("        automatically determine the top of the design hierarchy and mark it.\n");
+               log("\n");
                log("In -generate mode this pass generates blackbox modules for the given cell\n");
                log("types (wildcards supported). For this the design is searched for cells that\n");
                log("match the given types and then the given port declarations are used to\n");
@@ -391,6 +405,7 @@ struct HierarchyPass : public Pass {
                RTLIL::Module *top_mod = NULL;
                std::vector<std::string> libdirs;
 
+               bool auto_top_mode = false;
                bool generate_mode = false;
                bool keep_positionals = false;
                bool nokeep_asserts = false;
@@ -472,6 +487,10 @@ struct HierarchyPass : public Pass {
                                        log_cmd_error("Module `%s' not found!\n", args[argidx].c_str());
                                continue;
                        }
+                       if (args[argidx] == "-auto-top") {
+                               auto_top_mode = true;
+                               continue;
+                       }
                        break;
                }
                extra_args(args, argidx, design, false);
@@ -483,11 +502,24 @@ struct HierarchyPass : public Pass {
 
                log_push();
 
-               if (top_mod == NULL)
+               if (top_mod == nullptr)
                        for (auto &mod_it : design->modules_)
                                if (mod_it.second->get_bool_attribute("\\top"))
                                        top_mod = mod_it.second;
 
+               if (top_mod == nullptr && auto_top_mode) {
+                       log_header("Finding top of design hierarchy..\n");
+                       dict<Module*, int> db;
+                       for (Module *mod : design->modules()) {
+                               int score = find_top_mod_score(design, mod, db);
+                               log("root of %3d design levels: %-20s\n", score, log_id(mod));
+                               if (!top_mod || score > db[top_mod])
+                                       top_mod = mod;
+                       }
+                       if (top_mod != nullptr)
+                               log("Automatically selected %s as design top module.\n", log_id(top_mod));
+               }
+
                bool did_something = true;
                while (did_something)
                {