Back end question.

[Dmitry]

Yes but as you've said, it's a carry flag setter, but how could this example be transformed if I need to store not only carry flag but also for example a zero flag? Could you write such an example, please?
Thanks.
Dmitry.

--- Èñõîäíîå ñîîáùåíèå ---
 Îò êîãî: "Ian Lance Taylor" <iant@google.com> 
 Êîìó: "Dmitry" <mittie@ukr.net> 
 Äà òà : 5 ìà ÿ 2011, 17:41:38 
 Òåìà : Re: Back end question. 
 


> "Dmitry" <mittie@ukr.net> writes:
> 
> > Ok but if people do not set each status bit individually, how do they set several not related bits in one CC mode and in one set rtx?
> 
> They represent the collection of bits as a mode, as you've been
> discussing.
> 
> E.g., from config/i386/i386.md
> 
> (define_insn "*<plusminus_insn><mode>3_cc_overflow"
>  [(set (reg:CCC FLAGS_REG)
>  (compare:CCC
>  (plusminus:SWI
>  (match_operand:SWI 1 "nonimmediate_operand" "<comm>0,0")
>  (match_operand:SWI 2 "<general_operand>" "<r><i>,<r>m"))
>  (match_dup 1)))
>  (set (match_operand:SWI 0 "nonimmediate_operand" "=<r>m,<r>")
>  (plusminus:SWI (match_dup 1) (match_dup 2)))]
>  "ix86_binary_operator_ok (<CODE>, <MODE>mode, operands)"
>  "<plusminus_mnemonic>{<imodesuffix>}\t{%2, %0|%0, %2}"
>  [(set_attr "type" "alu")
>  (set_attr "mode" "<MODE>")])
> 
> 
> Here the CCC mode (defined in i386-modes.def) means that the carry flag
> is valid.
> 
> Ian
> 
>