Extracting operands from rtl instructions

Chung-Ju Wu jasonwucj@gmail.com
Mon Aug 5 17:31:00 GMT 2013


2013/8/6 Abdul Wahid Memon <engrwahidmemon@gmail.com>:
> Thanks Chung-Ju. But how can I determine the number of operands for
> any machine instruction?
>
> Number of operands do vary for various instructions and there must be
> some way to determine this number.
>
> Regards
>
> Abdul
>

According to GCC Internal chapter 10.1:
"The expression code determines how many operands the expression contains,
 and what kinds of objects they are."

Also, refer to gcc/rtl.h:
"/* The first element of the operands of this rtx.
    The number of operands and their types are controlled
    by the `code' field, according to rtl.def.  */"

The rtx code/patterns are listed in Chatper 10.
So I think you need to identify rtx code first then
you can determine the number of operands.


Best regards,
jasonwucj



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