The XOR trick also introduces data dependencies that makes it slower on some CPUs (can’t start the second XOR until the result of the first is available, or the

The XOR trick also introduces data dependencies that makes it slower on some CPUs (can’t start the second XOR until the result of the first is available, or the third one until the result of the second is available) When using a third register, CPUs with register renaming need not even move data at all. They could move the labels “register A”, “register B” around.