From 116c2496011aeeac9847d69af597a0db58209793 Mon Sep 17 00:00:00 2001
From: Eddie Hung <eddie@fpgeh.com>
Date: Wed, 28 Aug 2019 19:59:25 -0700
Subject: [PATCH] -auto-top should check $abstract (deferred) modules with (*
 top *)

---
 passes/hierarchy/hierarchy.cc | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/passes/hierarchy/hierarchy.cc b/passes/hierarchy/hierarchy.cc
index fd95b94b2..ad795c69f 100644
--- a/passes/hierarchy/hierarchy.cc
+++ b/passes/hierarchy/hierarchy.cc
@@ -808,6 +808,37 @@ struct HierarchyPass : public Pass {
 				if (mod_it.second->get_bool_attribute("\\top"))
 					top_mod = mod_it.second;
 
+		if (top_mod != nullptr && auto_top_mode) {
+			IdString abstract_id = top_mod->name;
+			IdString top_name = abstract_id;
+			if (top_name.begins_with("$abstract"))
+				top_name = top_name.substr(strlen("$abstract"));
+			top_mod = design->module(top_name);
+
+			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();
+			}
+
+			if (top_mod == nullptr && design->module(abstract_id))
+				top_mod = design->module(design->module(abstract_id)->derive(design, top_parameters));
+			else if (top_mod != nullptr && !top_parameters.empty())
+				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;
-- 
2.30.2