https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101676
--- Comment #3 from Jeffrey A. Law <law at gcc dot gnu.org> --- In response to c#2, in addition to Andrew's comments, some ISAs have limited support for XOR, but robust IOR support (denser encoding, support for immediates, etc). Essentially they realized that XOR wasn't used as much and thus didn't burn opcode space on XOR variants that just wouldn't have been used that heavily.
