> For instance C doesn't let you retrieve the 64-bit result from a 32x32-bit multiply. You have to cast the operands to 64-bit first to get the result even thou

> For instance C doesn't let you retrieve the 64-bit result from a 32x32-bit multiply. You have to cast the operands to 64-bit first to get the result even though the hardware provides the answer you want without any extra steps. Any optimizing compiler should generate a single 32-bit MUL for uint64_t z = (uint64_t) x * (uint64_t) y. It's easy for instruction selection to match against such patterns. A better example would be generating a single instruction for the 128-bit product of 64-bit integers on a 64-bit processor. There are no standard types for 128-bit integers, but you can still avoid assembly code by using compiler-specific types or intrinsics. With GCC, Clang and ICC, you can write unsigned __int128 z = (unsigned __int128) x * (unsigned __int128) y. The odd one out is MSVC, where you have to use the _umul128 intrisic.