solidity/test/libsolidity/semanticTests/various/code_length.sol

// SPDX-License-Identifier: GPL-3.0
contract C {
    uint len1;
    uint len2;
    constructor() {
        uint mem_ptr_before;
        uint mem_ptr_after;

        assembly {
            mem_ptr_before := mload(64)
        }

        len1 = address(0).code.length;

        assembly {
            mem_ptr_after := mload(64)
        }

        // To check that no memory was allocated and written.
        assert(mem_ptr_before == mem_ptr_after);

        len2 = address(this).code.length;

        // To check that no memory was allocated and written.
        assembly {
            mem_ptr_after := mload(64)
        }

        assert(mem_ptr_before == mem_ptr_after);

    }

    function f() public view returns (bool r1, bool r2) {
        uint mem_ptr_before;
        uint mem_ptr_after;

        assembly {
            mem_ptr_before := mload(64)
        }

        r1 = address(this).code.length > 50;

        assembly {
            mem_ptr_after := mload(64)
        }

        // To check that no memory was allocated and written.
        assert(mem_ptr_before == mem_ptr_after);

        address a = address(0);
        r2 = a.code.length == 0;

        // To check that no memory was allocated and written.
        assembly {
            mem_ptr_after := mload(64)
        }

    }
}
// ----
// constructor()
// gas legacy: 124168
// f(): true, true -> true, true