http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49195
--- Comment #4 from Segher Boessenkool <segher at gcc dot gnu.org> 2011-05-27 20:14:05 UTC --- This is the match_op_dup operand in (define_insn "" [(set (match_operand:CC 0 "cc_reg_operand" "=x,?y") (compare:CC (match_operator:SI 1 "scc_comparison_operator" [(match_operand 2 "cc_reg_operand" "y,y") (const_int 0)]) (const_int 0))) (set (match_operand:SI 3 "gpc_reg_operand" "=r,r") (match_op_dup 1 [(match_dup 2) (const_int 0)]))] "TARGET_32BIT" "@ mfcr %3%Q2\;{rlinm.|rlwinm.} %3,%3,%J1,1 #" [(set_attr "type" "delayed_compare") (set_attr "length" "8,16")]) and the similar define_split.