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Re: Question about "match_dup"


fishbaoz@hotmail.com wrote:
> What is the exact meaning of "match_dup"?
> 
> the following is extracted from "mips.md"
> 
> (define_expand "movsicc"
>   [(set (match_dup 4) (match_operand 1 "comparison_operator" ""))
>    (set (match_operand:SI 0 "register_operand" "")
>  (if_then_else:SI (match_dup 5)
>     (match_operand:SI 2 "reg_or_0_operand" "")
>     (match_operand:SI 3 "reg_or_0_operand" "")))]
>   "mips_isa >= 4"
>   "
> {
>   gen_conditional_move (operands);
>   DONE;
> }")
> 
> Now?
> what is the meaning of "match_dup" in the machine description above?
> what does it "duplicate"? Operand(4)? where is the original Operand(4)?
> 
> 

Usually, this sort of thing refers to an operand that is manufactured in
the define_expand.  I don't see that going on here, though, so I'm at a
loss.

Anybody know?

 - ken


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