https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78821
--- Comment #26 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Comment on attachment 42661 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=42661 Add bswaphi2 pattern [(set (match_operand:HI 0 "register_operand") Is that so that you don't have to bother with forcing operands[1] into a reg if operands[0] is a MEM and not equal to operands[1]? The disadvantage of your approach is that the RA will have fewer possibilities (for -m32 not being able to use %si/%di/%bp, and for all arches not being able to do 16-bit bswap on memory directly (rolw $8, mem). Guess the latter could be fixed by another peephole2, the former can't. On the other side, it has the advantage that flags aren't clobbered from the beginning, so perhaps sched1 or similar can do a better job.
