message: Implement missing intrinsic
diff: @@ -315,6 +315,20 @@ impl<'a, 'mir, 'tcx> EvalContextExt<'tcx> for EvalContext<'a, 'mir, 'tcx, super:
  self.write_primval(dest, result.0, dest_layout.ty)?;
  }
  + "exact_div" => {
  + // Performs an exact division, resulting in undefined behavior where
  + // `x % y != 0` or `y == 0` or `x == T::min_value() && y == -1`
  + let ty = substs.type_at(0);
  + let a = self.value_to_primval(args[0])?;
  + let b = self.value_to_primval(args[1])?;
  + // check x % y != 0
  + if self.binary_op(mir::BinOp::Rem, a, ty, b, ty)?.0 != PrimVal::Bytes(0) {
  + return err!(ValidationFailure(format!("exact_div: {:?} cannot be divided by {:?}", a, b)));
  + }
  + let result = self.binary_op(mir::BinOp::Div, a, ty, b, ty)?;
  + self.write_primval(dest, result.0, dest_layout.ty)?;
  + },
  +
  "likely" | "unlikely" | "forget" => {}
  "init" => {
  