Support multiple rounds of opt_design in Innovus plugin

hammer/par/innovus/__init__.py

@@ -637,7 +637,10 @@ def opt_design(self) -> bool:
         Post-route optimization and fix setup & hold time violations.
         -expanded_views creates timing reports for each MMMC view.
         """
-        self.verbose_append("opt_design -post_route -setup -hold -expanded_views")
+        rounds = self.get_setting("par.innovus.opt_design_rounds")
+        assert rounds > 0
+        for r in range(rounds):
+            self.verbose_append("opt_design -post_route -setup -hold -expanded_views")
         if self.hierarchical_mode.is_nonleaf_hierarchical():
             self.verbose_append("unflatten_ilm")
         return True

hammer/par/innovus/defaults.yml

@@ -35,3 +35,7 @@ par.innovus:
   # Note that this requires an optional licence (enccco).
   # type: bool
   use_cco: true
+
+  # How many iterations to run opt_design
+  # If the first opt_design fails to converge by a small margin, the second run may achieve closure
+  opt_design_rounds: 1