[RSA Accumulator] Reduce code size

[nrryuya]

For now, the code (merged in #70) can't be deployed due to the excess of the code size: eth.exceptions.OutOfGas: Contract code size exceeds EIP170 limit of 24577. Got code of size: 55782

• The size of the Solidity implementation is 6713 with Remix IDE.

• The size of the code of big integer arithmetic is around 30000...

For analysis.

• LLL of Vyper version
• Assembly of Solidity version

Suspects

• There are a tremendous number of mstore and mload in the LLL.

  • Vyper uses them a lot to call private functions.
  • For example, the first part in the LLL of def _convertBytesArrayToUInt256List(_inp: bytes[256]) -> uint256[8]: has a sequence of 231 of mload.

                  [mload, 320],
                  [mload, 352],
                  [mload, 384],
                  [mload, 416],
                  [mload, 448],
                  [mload, 480],
                  [mload, 512],
                  [mload, 544],
                  [mload, 576],
                  [mload, 608],
                  [mload, 640],
                  [mload, 672],
    # Continuing...

• The code below in Line 225 is compiled to a complicated LLL

  multiplicationResult = _primes[4 * i] * _primes[4 * i + 1] * _primes[4 * i + 2] * _primes[4 * i + 3]

Workarounds

• Change private -> public
• Put codes in private functions inline