Most gas efficient way to check that two integers have the same sign in Solidity

checkSameSign.sol

// SPDX-License-Identifier: UNLICENSED
pragma solidity >=0.8.15;

function checkSameSign(int256 a, int256 b) pure returns (bool sameSign) {
    // Get the signs of a and b.
    uint256 sa;
    uint256 sb;
    assembly {
        // This works due to two's complement representation.
        // "sgt" stamds for "signed greater than".
        sa := sgt(a, sub(0, 1))
        sb := sgt(b, sub(0, 1))
    }

    // If XOR over sa and sb yields 0, a and b are of the same sign.
    sameSign = sa ^ sb == 0;
}