Are you sure about that? 128 bit compare and swap has been on x64 for two decades and ARM has it too. I thought PPC also had it. None of these (as far as I kno

Are you sure about that? 128 bit compare and swap has been on x64 for two decades and ARM has it too. I thought PPC also had it. None of these (as far as I know) can actually do a 128 bit compare and swap when it straddles two cache lines however. These also aren't the same as doing actual 128 bit math operations, they are just for compare and swap.