Merge pull request #1338 from YosysHQ/eddie/deferred_top

hierarchy -auto-top to work with (* top *) modules from read/read_verilog -defer

frontends/ast/ast.cc

@@ -1099,6 +1099,13 @@ static AstModule* process_module(AstNode *ast, bool defer, AstNode *original_ast
 
 		ignoreThisSignalsInInitial = RTLIL::SigSpec();
 	}
+	else {
+		for (auto &attr : ast->attributes) {
+			if (attr.second->type != AST_CONSTANT)
+				continue;
+			current_module->attributes[attr.first] = attr.second->asAttrConst();
+		}
+	}
 
 	if (ast->type == AST_INTERFACE)
 		current_module->set_bool_attribute("\\is_interface");

passes/hierarchy/hierarchy.cc

@@ -808,6 +808,30 @@ struct HierarchyPass : public Pass {
 				if (mod_it.second->get_bool_attribute("\\top"))
 					top_mod = mod_it.second;
 
+		if (top_mod != nullptr && top_mod->name.begins_with("$abstract")) {
+			IdString top_name = top_mod->name.substr(strlen("$abstract"));
+
+			dict<RTLIL::IdString, RTLIL::Const> top_parameters;
+			for (auto &para : parameters) {
+				SigSpec sig_value;
+				if (!RTLIL::SigSpec::parse(sig_value, NULL, para.second))
+					log_cmd_error("Can't decode value '%s'!\n", para.second.c_str());
+				top_parameters[RTLIL::escape_id(para.first)] = sig_value.as_const();
+			}
+
+			top_mod = design->module(top_mod->derive(design, top_parameters));
+
+			if (top_mod != nullptr && top_mod->name != top_name) {
+				Module *m = top_mod->clone();
+				m->name = top_name;
+				Module *old_mod = design->module(top_name);
+				if (old_mod)
+					design->remove(old_mod);
+				design->add(m);
+				top_mod = m;
+			}
+		}
+
 		if (top_mod == nullptr && auto_top_mode) {
 			log_header(design, "Finding top of design hierarchy..\n");
 			dict<Module*, int> db;

tests/various/hierarchy_defer.ys

@@ -0,0 +1,27 @@
+read -noverific
+read -vlog2k <<EOT
+module first;
+endmodule
+
+(* top *)
+module top(input i, output o);
+sub s0(i, o);
+endmodule
+
+(* constant_expression=1+1?2*2:3/3 *)
+module sub(input i, output o);
+assign o = ~i;
+endmodule
+EOT
+design -save read
+
+hierarchy -auto-top
+select -assert-any top
+select -assert-any sub
+select -assert-none foo
+
+design -load read
+hierarchy
+select -assert-any top
+select -assert-any sub
+select -assert-none foo