3 files changed, 33 insertions, 8 deletions

diff --git a/kernel/hashlib.h b/kernel/hashlib.h
index 996bda38e..97fadea0e 100644
--- a/kernel/hashlib.h
+++ b/kernel/hashlib.h
@@ -569,7 +569,7 @@ public:
 		return entries[i].udata.second;
 	}
 
-	T at(const K &key, const T &defval) const
+	const T& at(const K &key, const T &defval) const
 	{
 		int hash = do_hash(key);
 		int i = do_lookup(key, hash);
@@ -961,7 +961,21 @@ class idict
 	pool<K, OPS> database;
 
 public:
-	typedef typename pool<K, OPS>::const_iterator const_iterator;
+	class const_iterator : public std::iterator<std::forward_iterator_tag, K>
+	{
+		friend class idict;
+	protected:
+		const idict &container;
+		int index;
+		const_iterator(const idict &container, int index) : container(container), index(index) { }
+	public:
+		const_iterator() { }
+		const_iterator operator++() { index++; return *this; }
+		bool operator==(const const_iterator &other) const { return index == other.index; }
+		bool operator!=(const const_iterator &other) const { return index != other.index; }
+		const K &operator*() const { return container[index]; }
+		const K *operator->() const { return &container[index]; }
+	};
 
 	int operator()(const K &key)
 	{
@@ -1019,9 +1033,9 @@ public:
 	bool empty() const { return database.empty(); }
 	void clear() { database.clear(); }
 
-	const_iterator begin() const { return database.begin(); }
-	const_iterator element(int n) const { return database.element(n); }
-	const_iterator end() const { return database.end(); }
+	const_iterator begin() const { return const_iterator(*this, offset); }
+	const_iterator element(int n) const { return const_iterator(*this, n); }
+	const_iterator end() const { return const_iterator(*this, offset + size()); }
 };
 
 template<typename K, typename OPS>
diff --git a/kernel/rtlil.cc b/kernel/rtlil.cc
index 8af941c85..2aefe30b1 100644
--- a/kernel/rtlil.cc
+++ b/kernel/rtlil.cc
@@ -1389,7 +1389,7 @@ void RTLIL::Module::sort()
 {
 	wires_.sort(sort_by_id_str());
 	cells_.sort(sort_by_id_str());
-	avail_parameters.sort(sort_by_id_str());
+	parameter_default_values.sort(sort_by_id_str());
 	memories.sort(sort_by_id_str());
 	processes.sort(sort_by_id_str());
 	for (auto &it : cells_)
@@ -1508,6 +1508,7 @@ void RTLIL::Module::cloneInto(RTLIL::Module *new_mod) const
 	log_assert(new_mod->refcount_cells_ == 0);
 
 	new_mod->avail_parameters = avail_parameters;
+	new_mod->parameter_default_values = parameter_default_values;
 
 	for (auto &conn : connections_)
 		new_mod->connect(conn);
@@ -2618,7 +2619,16 @@ void RTLIL::Cell::setParam(RTLIL::IdString paramname, RTLIL::Const value)
 
 const RTLIL::Const &RTLIL::Cell::getParam(RTLIL::IdString paramname) const
 {
-	return parameters.at(paramname);
+	static const RTLIL::Const empty;
+	const auto &it = parameters.find(paramname);
+	if (it != parameters.end())
+		return it->second;
+	if (module && module->design) {
+		RTLIL::Module *m = module->design->module(type);
+		if (m)
+			return m->parameter_default_values.at(paramname, empty);
+	}
+	return empty;
 }
 
 void RTLIL::Cell::sort()
diff --git a/kernel/rtlil.h b/kernel/rtlil.h
index f3b1c9ae7..11c45bbec 100644
--- a/kernel/rtlil.h
+++ b/kernel/rtlil.h
@@ -1091,7 +1091,8 @@ public:
 	std::vector<RTLIL::SigSig> connections_;
 
 	RTLIL::IdString name;
-	pool<RTLIL::IdString> avail_parameters;
+	idict<RTLIL::IdString> avail_parameters;
+	dict<RTLIL::IdString, RTLIL::Const> parameter_default_values;
 	dict<RTLIL::IdString, RTLIL::Memory*> memories;
 	dict<RTLIL::IdString, RTLIL::Process*> processes;