perf[venom]: add OrderedSet.last() (#4236)

smidge performance improvement (roughly 3%). peek directly at end of
`OrderedSet` instead of converting to list every time.

.github/workflows/pull-request.yaml

@@ -24,6 +24,7 @@ jobs:
         with:
           types: |
             feat
+            perf
             fix
             chore
             refactor

vyper/utils.py

@@ -36,6 +36,9 @@ def __repr__(self):
     def __iter__(self):
         return iter(self._data)
 
+    def __reversed__(self):
+        return reversed(self._data)
+
     def __contains__(self, item):
         return self._data.__contains__(item)
 
@@ -45,6 +48,9 @@ def __len__(self):
     def first(self):
         return next(iter(self))
 
+    def last(self):
+        return next(reversed(self))
+
     def pop(self):
         return self._data.popitem()[0]
 

vyper/venom/venom_to_assembly.py

@@ -530,8 +530,7 @@ def _generate_evm_for_instruction(
             else:
                 # peek at next_liveness to find the next scheduled item,
                 # and optimistically swap with it
-                # TODO: implement OrderedSet.last()
-                next_scheduled = list(next_liveness)[-1]
+                next_scheduled = next_liveness.last()
                 self.swap_op(assembly, stack, next_scheduled)
 
         return apply_line_numbers(inst, assembly)