About "define_expand" having names which are not standard pattern names.

[mike@csdn.sign.idv.tw]

Hello,
    
    After I have read the i386.md file of gcc, I got confused.

(define_expand "sse2_loadsd"
  [(match_operand:V2DF 0 "register_operand" "")
     (match_operand:DF 1 "memory_operand" "")]
       "TARGET_SSE2"
       {
         emit_insn (gen_sse2_loadsd_1 (operands[0], operands[1],
				         CONST0_RTX (V2DFmode)));
        DONE;
 })

I know that "define_expand" is used to expand the standard pattern
name into multiple RTL, but the name "sse2_loadsd" is not a standard
pattern name. What does this kind of "define_expand" mean?

Thanks.


Mike Wu