> > (define_insn "*arm_movqi_insn" > > [(set (match_operand:QI 0 "nonimmediate_operand" "=r,r,r,Q") > > (match_operand:QI 1 "general_operand" "rI,K,m,+r"))] > Changing "m" to "Q", narrowing the address modes > Changing "r" to "+r", (register is globbered)
This is wrong. the "+" applies to the operand, not the individual alternative (thus should go at the start of the constraint string). Also, I doubt you can just say "movqi clobbers its input". I expect you still have to effectively do the same as if you were doing a read-modify-write implementation. Otherwise reload will get very upset with you. swpb effectively just implements that in a single instruction rather than having to do it manually. See the alpha backend for an example of how this can be implemented. Paul
