Optimized IR:
/*******************************************************
 *                       WARNING                       *
 *  Solidity to Yul compilation is still EXPERIMENTAL  *
 *       It can result in LOSS OF FUNDS or worse       *
 *                !USE AT YOUR OWN RISK!               *
 *******************************************************/

object "Arraysum_34" {
    code {
        {
            mstore(64, 128)
            if callvalue() { revert(0, 0) }
            let _1 := datasize("Arraysum_34_deployed")
            codecopy(0, dataoffset("Arraysum_34_deployed"), _1)
            return(0, _1)
        }
    }
    object "Arraysum_34_deployed" {
        code {
            {
                mstore(64, 128)
                if iszero(lt(calldatasize(), 4))
                {
                    let _1 := 0
                    if eq(0x81d73423, shr(224, calldataload(_1)))
                    {
                        if callvalue() { revert(_1, _1) }
                        if slt(add(calldatasize(), not(3)), _1) { revert(_1, _1) }
                        let var_sum := _1
                        let var_i := _1
                        let _2 := sload(_1)
                        for { }
                        lt(var_i, _2)
                        {
                            if eq(var_i, not(0)) { panic_error_0x11() }
                            var_i := add(var_i, 1)
                        }
                        {
                            mstore(_1, _1)
                            var_sum := checked_add_uint256(var_sum, sload(add(keccak256(_1, 0x20), var_i)))
                        }
                        let memPos := mload(64)
                        return(memPos, sub(abi_encode_uint256(memPos, var_sum), memPos))
                    }
                }
                revert(0, 0)
            }
            function abi_encode_uint256(headStart, value0) -> tail
            {
                tail := add(headStart, 32)
                mstore(headStart, value0)
            }
            function checked_add_uint256(x, y) -> sum
            {
                if gt(x, not(y)) { panic_error_0x11() }
                sum := add(x, y)
            }
            function panic_error_0x11()
            {
                mstore(0, shl(224, 0x4e487b71))
                mstore(4, 0x11)
                revert(0, 0x24)
            }
        }
    }
}