DowncastUseVsUseDowncast.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0; // optimize 200

/**
 * @title DowncastUseVsUseDowncast
 * @author IllIllI
 */
contract DowncastUseVsUseDowncast {
    function test() external view returns (uint8) {
        uint8 varr = uint8(block.number >> 255);
        varr = varr + 1;                        // 21359 gas
        //varr = varr + uint8(block.number);    // 21461 (adds 102 gas)
        //varr = varr + 2;                      // 21564 (adds 103 gas)
        //varr = varr + uint8(block.timestamp); // 21666 (adds 102 gas)
        return varr;
    }

    function test2() external view returns (uint8) {
        uint256 varr = block.number >> 255;
        varr = varr + 1;                        // 21331 gas
        //varr = varr + block.number;             // 21405 (adds 74 gas)
        //varr = varr + 2;                        // 21480 (adds 75 gas)
        //varr = varr + block.timestamp;          // 21554 (adds 74 gas)
        return uint8(varr);
    }

}