assume_early option to implement cross assumes in IVY

Checking IVY's cross assumes requires delaying a subset of assumptions,
which we don't want SBY to undo.

sbysrc/sby_core.py

@@ -989,7 +989,8 @@ def make_model(self, model_name):
  print("clk2fflogic", file=f)
  else:
  print("async2sync", file=f)
- print("chformal -assume -early", file=f)
+ if self.opt_assume_early:
+ print("chformal -assume -early", file=f)
  print("opt_clean", file=f)
  print("formalff -setundef -clk2ff -ff2anyinit -hierarchy", file=f)
  if self.opt_mode in ["bmc", "prove"]:
@@ -1252,6 +1253,8 @@ def handle_non_engine_options(self):
  self.handle_str_option("make_model", None)
  self.handle_bool_option("skip_prep", False)
 
+ self.handle_bool_option("assume_early", True)
+
  def setup_procs(self, setupmode):
  self.handle_non_engine_options()
  if self.opt_smtc is not None: