A question here is whether this trick (which I acknowledge is very interesting) is worth doing on Broadwell. Broadwell has a pair of new instructions (ADCX and

A question here is whether this trick (which I acknowledge is very interesting) is worth doing on Broadwell. Broadwell has a pair of new instructions (ADCX and ADOX) that don't behave like a normal ADC - they only read and set a single bit (carry bit and overflow bit). As such you can do two of these at once and at least on recent Intel processors there are two execution ports (0 and 6) that can handle these instructions. You'd still need some cleverness if your goal is to add just one giant bignum (as opposed to doing lots of independent add-with-carry sums).