Use set for strpool_attribute to maintain ordering, but keep some backwards compatibility

kernel/hashlib.h

@@ -14,6 +14,7 @@
 
 #include <stdexcept>
 #include <algorithm>
+#include <set>
 #include <string>
 #include <variant>
 #include <vector>
@@ -1001,6 +1002,11 @@ public:
 	{
 	}
 
+	pool(std::set<K> other) {
+		for (auto it : other)
+			insert(it);
+	}
+
 	pool(const pool &other)
 	{
 		entries = other.entries;

kernel/rtlil.cc

@@ -708,6 +708,14 @@ void RTLIL::AttrObject::add_strpool_attribute(const RTLIL::IdString& id, const s
 		set_strpool_attribute(id, union_data);
 }
 
+void RTLIL::AttrObject::add_strpool_attribute(const RTLIL::IdString& id, const pool<string> &data)
+{
+	std::set<string> union_data = get_strpool_attribute(id);
+	union_data.insert(data.begin(), data.end());
+	if (!union_data.empty())
+		set_strpool_attribute(id, union_data);
+}
+
 std::set<string> RTLIL::AttrObject::get_strpool_attribute(const RTLIL::IdString &id) const
 {
 	std::set<string> data;

kernel/rtlil.h

@@ -857,6 +857,7 @@ struct RTLIL::AttrObject
 
 	void set_strpool_attribute(const RTLIL::IdString& id, const std::set<string> &data);
 	void add_strpool_attribute(const RTLIL::IdString& id, const std::set<string> &data);
+	void add_strpool_attribute(const RTLIL::IdString& id, const pool<string> &data);
 	std::set<string> get_strpool_attribute(const RTLIL::IdString &id) const;
 
 	void set_src_attribute(const std::string &src) {

passes/techmap/techmap.cc

@@ -26,7 +26,6 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
-#include <set>
 
 #include "simplemap.h"
 
@@ -157,7 +156,7 @@ struct TechmapWorker
 		}
 
 		std::string orig_cell_name;
-		std::set<string> extra_src_attrs = cell->get_strpool_attribute(ID::src);
+		pool<string> extra_src_attrs = cell->get_strpool_attribute(ID::src);
 
 		orig_cell_name = cell->name.str();
 		for (auto tpl_cell : tpl->cells())