While AMD GPU can&#x27;t do 64x64 multiplies that give 128-bit results, they still can do a 32x32 multiply with a 64-bit result. (MULHI_<i>INT and MULLO_</i>INT instructions).<p>And you can do add-with-carry manually on the AMD GPU using two instructions: ADDC_UINT to get the carry flag from an addition followed by ADD_PREV to add it.