Range check for dynamic field length

[mikir]

There is no range check for dynamic field length during runtime. Example:

struct Container
{
    uint64      length;
    bit<length> unsignedBitField;
    int<length> signedBitField;
};

It would be nice to have runtime range check that length is not bigger than 64. Currently, this issue is reported only during writing without any specification of problematic field.

[Mi-La]

Note that with -withRangeCheckCode the check for maximum numbits is done (see BitFieldUtil.cpp, bitfield.py, Util.java. It's only missing in Java for unsigned bitfields which are mapped to BigInteger. However it's only a part of range check, which primary task is to check the range of the stored value, not the number of bits. The length should be checked even -withoutRangeCheckCode. Currently in Java it's possible to write/read dynamic unsigned bitfield with length > 64bits.