- ty::TyBool => PrimVal::Bool(try!(self.memory.read_bool(ptr))),
- ty::TyInt(IntTy::I8) => PrimVal::I8(try!(self.memory.read_int(ptr, 1)) as i8),
- ty::TyInt(IntTy::I16) => PrimVal::I16(try!(self.memory.read_int(ptr, 2)) as i16),
- ty::TyInt(IntTy::I32) => PrimVal::I32(try!(self.memory.read_int(ptr, 4)) as i32),
- ty::TyInt(IntTy::I64) => PrimVal::I64(try!(self.memory.read_int(ptr, 8)) as i64),
- ty::TyUint(UintTy::U8) => PrimVal::U8(try!(self.memory.read_uint(ptr, 1)) as u8),
- ty::TyUint(UintTy::U16) => PrimVal::U16(try!(self.memory.read_uint(ptr, 2)) as u16),
- ty::TyUint(UintTy::U32) => PrimVal::U32(try!(self.memory.read_uint(ptr, 4)) as u32),
- ty::TyUint(UintTy::U64) => PrimVal::U64(try!(self.memory.read_uint(ptr, 8)) as u64),
+ ty::TyBool => PrimVal::Bool(self.memory.read_bool(ptr)?),
+ ty::TyInt(IntTy::I8) => PrimVal::I8(self.memory.read_int(ptr, 1)? as i8),
+ ty::TyInt(IntTy::I16) => PrimVal::I16(self.memory.read_int(ptr, 2)? as i16),
+ ty::TyInt(IntTy::I32) => PrimVal::I32(self.memory.read_int(ptr, 4)? as i32),
+ ty::TyInt(IntTy::I64) => PrimVal::I64(self.memory.read_int(ptr, 8)? as i64),
+ ty::TyUint(UintTy::U8) => PrimVal::U8(self.memory.read_uint(ptr, 1)? as u8),
+ ty::TyUint(UintTy::U16) => PrimVal::U16(self.memory.read_uint(ptr, 2)? as u16),
+ ty::TyUint(UintTy::U32) => PrimVal::U32(self.memory.read_uint(ptr, 4)? as u32),
+ ty::TyUint(UintTy::U64) => PrimVal::U64(self.memory.read_uint(ptr, 8)? as u64),