restore assembly swap

charles-cooper · Nov 20, 2024 · 24e9615 · 24e9615
1 parent 367baa3
commit 24e9615
Showing 1 changed file with 7 additions and 0 deletions.
diff --git a/vyper/venom/venom_to_assembly.py b/vyper/venom/venom_to_assembly.py
@@ -434,6 +434,13 @@ def _generate_evm_for_instruction(
             # the same variable, however, before a jump that is not possible
             self._stack_reorder(assembly, stack, list(target_stack))
 
+        if inst.is_commutative:
+            cost_no_swap = self._stack_reorder([], stack, operands, dry_run=True)
+            operands[-1], operands[-2] = operands[-2], operands[-1]
+            cost_with_swap = self._stack_reorder([], stack, operands, dry_run=True)
+            if cost_with_swap > cost_no_swap:
+                operands[-1], operands[-2] = operands[-2], operands[-1]
+
         cost = self._stack_reorder([], stack, operands, dry_run=True)
         if DEBUG_SHOW_COST and cost:
             print("ENTER", inst, file=sys.stderr)