message: When meet float register, ignore and warn rather than panic
diff: @@ -514,8 +514,12 @@ impl<'a, T: SSAMod<BBInfo=MAddress> + SSAExtra + 'a> PhiPlacer<'a, T> {
  let info = match self.regfile.get_subregister(var) {
  Some(reg) => reg,
  None => {
  - writeln!(io::stderr(), "Error: Radeco haven't supported float nowadays");
  - process::exit(1);
  + //writeln!(io::stderr(), "Error: Radeco haven't supported float nowadays");
  + //process::exit(1);
  + radeco_warn!("Nowadays, radeco could not support float operation");
  + let vt = ValueType::Integer{ width: 0 };
  + let node = self.add_undefined(address.to_owned(), vt);
  + return node;
  }
  };
  let id = info.base;
  @@ -551,7 +555,13 @@ impl<'a, T: SSAMod<BBInfo=MAddress> + SSAExtra + 'a> PhiPlacer<'a, T> {
  radeco_trace!("phip_write_reg|{}<-{:?}", var, value);
  - let info = self.regfile.get_subregister(var).unwrap();
  + let info = match self.regfile.get_subregister(var) {
  + Some(reg) => reg,
  + None => {
  + radeco_warn!("Nowadays, radeco could not support float operation");
  + return;
  + }
  + };
  let id = info.base;
  