message: exit when facing float, rather than panic
diff: use std::collections::{BTreeMap, HashMap, HashSet};
  use std::cmp::Ordering;
  use std::u64;
  +use std::io::{self, Write};
  +use std::process;
  use middle::ssa::ssa_traits::{SSAMod, ValueType};
  use middle::ir::MAddress;
  @@ -493,7 +495,13 @@ impl<'a, T: SSAMod<BBInfo=MAddress> + 'a> PhiPlacer<'a, T> {
  pub fn read_register(&mut self, address: &mut MAddress, var: &str) -> T::ValueRef {
  radeco_trace!("phip_read_reg|{}", var);
  - let info = self.regfile.get_info(var).expect("No register found");
  + let info = match self.regfile.get_info(var) {
  + Some(reg) => reg,
  + None => {
  + writeln!(io::stderr(), "Error: Radeco haven't supported float nowadays");
  + process::exit(1);
  + }
  + };
  let id = info.base;
  let mut value = self.read_variable(address, id);
  