Method dd_sub

crates/jit/src/instructions.rs:889–892

Subtracts DDValue b from DDValue a by negating b and then using the addition function.

(&mut self, a: DDValue, b: DDValue)

    /// Subtracts DDValue b from DDValue a by negating b and then using the addition function.
    fn dd_sub(&mut self, a: DDValue, b: DDValue) -> DDValue {
        let neg_b = self.dd_neg(b);
        self.dd_add(a, neg_b)
    }

    /// Multiplies two DDValue numbers using double–double arithmetic.
    /// It calculates the high product, uses a fused multiply–add (FMA) to capture rounding error,