Actually, in real use, the XOR swapping is almost always slower, because in practice the temp turns into: Read a into register1 Read b into register2

Actually, in real use, the XOR swapping is almost always slower, because in practice the temp turns into: Read a into register1 Read b into register2 Write register1 to a Write register2 to b Whereas with the xor, you read the values, then do some pointless xoring, then write them back out. Further, if you are using a and b for anything else, the 'tmp' turns into a simple register renaming, for 0 cost! While ^ swapping makes sense in assembler, it never makes sense in C.