message: fix FloatType::sizeVar()
diff: @@ -369,7 +369,7 @@ StateValue FloatType::fromBV(StateValue v) const {
  }
  expr FloatType::sizeVar() const {
  - return defined ? expr::mkUInt(getFpType(), var_bw_bits) : Type::sizeVar();
  + return defined ? expr::mkUInt(bits(), var_bw_bits) : Type::sizeVar();
  }
  StateValue FloatType::getDummyValue(bool non_poison) const {
  @@ -397,9 +397,12 @@ void FloatType::fixup(const Model &m) {
  if (defined)
  return;
  - unsigned fp_typ = m.getUInt(sizeVar());
  - assert(fp_typ < (unsigned)Unknown);
  - fpType = FpType(fp_typ);
  + switch (m.getUInt(sizeVar())) {
  + case 16: fpType = Half; break;
  + case 32: fpType = Float; break;
  + case 64: fpType = Double; break;
  + default: UNREACHABLE();
  + }
  }
  bool FloatType::isFloatType() const {
  