message: Nicer verifier errors
diff: @@ -60,7 +60,8 @@ pub fn trans_crate<'a, 'tcx: 'a>(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Box<Any> {
  match ::cretonne::codegen::verify_function(&f, &flags) {
  Ok(_) => {}
  Err(err) => {
  - tcx.sess.fatal(&format!("cretonne verify error: {}", err));
  + let pretty_error = ::cretonne::codegen::print_errors::pretty_verifier_error(&f, None, &err);
  + tcx.sess.fatal(&format!("cretonne verify error:\n{}", pretty_error));
  }
  }
  @@ -375,8 +376,8 @@ fn trans_stmt<'a, 'tcx: 'a>(fx: &mut FunctionCx<'a, 'tcx>, stmt: &Statement<'tcx
  }
  _ => unimplemented!("checked bin op {:?} for {:?}", bin_op, ty),
  };
  - lval.write_cvalue(fx, res);
  unimplemented!("checked bin op {:?}", bin_op);
  + lval.write_cvalue(fx, res);
  }
  Rvalue::UnaryOp(un_op, operand) => {
  let ty = fx.monomorphize(&operand.ty(&fx.mir.local_decls, fx.tcx));
  