diff --git a/kernel/sigtools.h b/kernel/sigtools.h
index 4e97bb775..2517d6de3 100644
--- a/kernel/sigtools.h
+++ b/kernel/sigtools.h
@@ -135,9 +135,11 @@ struct SigPool
 	}
 };
 
-template <typename T, class Compare = std::less<T>>
+template <typename T, class Compare = void>
 struct SigSet
 {
+	static_assert(!std::is_same<Compare,void>::value, "Default value for `Compare' class not found for SigSet<T>. Please specify.");
+
 	struct bitDef_t : public std::pair<RTLIL::Wire*, int> {
 		bitDef_t() : std::pair<RTLIL::Wire*, int>(NULL, 0) { }
 		bitDef_t(const RTLIL::SigBit &bit) : std::pair<RTLIL::Wire*, int>(bit.wire, bit.offset) { }
@@ -220,6 +222,13 @@ struct SigSet
 	}
 };
 
+template<typename T>
+class SigSet<T, typename std::enable_if<!std::is_pointer<T>::value>::type> : public SigSet<T, std::less<T>> {};
+template<typename T>
+using sort_by_name_id_guard = typename std::enable_if<std::is_same<T,RTLIL::Cell*>::value>::type;
+template<typename T>
+class SigSet<T, sort_by_name_id_guard<T>> : public SigSet<T, RTLIL::sort_by_name_id<typename std::remove_pointer<T>::type>> {};
+
 struct SigMap
 {
 	mfp<SigBit> database;
diff --git a/passes/techmap/alumacc.cc b/passes/techmap/alumacc.cc
index 5b168d524..034731b87 100644
--- a/passes/techmap/alumacc.cc
+++ b/passes/techmap/alumacc.cc
@@ -48,14 +48,25 @@ struct AlumaccWorker
 		RTLIL::SigSpec cached_cf, cached_of, cached_sf;
 
 		RTLIL::SigSpec get_lt() {
-			if (GetSize(cached_lt) == 0)
-				cached_lt = is_signed ? alu_cell->module->Xor(NEW_ID, get_of(), get_sf()) : get_cf();
+			if (GetSize(cached_lt) == 0) {
+				if (is_signed) {
+					get_of();
+					get_sf();
+					cached_lt = alu_cell->module->Xor(NEW_ID, cached_of, cached_sf);
+				}
+				else
+					cached_lt = get_cf();
+			}
 			return cached_lt;
 		}
 
 		RTLIL::SigSpec get_gt() {
-			if (GetSize(cached_gt) == 0)
-				cached_gt = alu_cell->module->Not(NEW_ID, alu_cell->module->Or(NEW_ID, get_lt(), get_eq()), false, alu_cell->get_src_attribute());
+			if (GetSize(cached_gt) == 0) {
+				get_lt();
+				get_eq();
+				SigSpec Or = alu_cell->module->Or(NEW_ID, cached_lt, cached_eq);
+				cached_gt = alu_cell->module->Not(NEW_ID, Or, false, alu_cell->get_src_attribute());
+			}
 			return cached_gt;
 		}