[bugfix] tags must be ascending not descending

python/dune/perftool/preambles.py

@@ -27,8 +27,8 @@ class UFL2LoopyDataCache(dict):
         self.counter = 0
 
     def register(self, cachekey, code, preamble):
-        self.counter = self.counter - 1
         self[cachekey] = (code, self.counter, preamble)
+        self.counter = self.counter + 1
 
     def extract_preambles(self):
         return [(p[1], p[0]) for p in self.values() if p[2]]