Re: duplicate a variable!!!!

[Jeff Kenton <jkenton at tilera dot com>]

On 03/30/2011 01:28 PM, Ian Lance Taylor wrote:
> Greicy.Costa-Marques@imag.fr writes:
>
> > I'd like to know if is possible to gcc to duplicate  a variable? for example
> >
> > ....
> > int a=2; i have this
> >
> > i want to do it: int a_1=2, a_2=2;
> >
> > I have a code in c and i want to modify the gcc so it makes the
> > duplication of the variable. i like to do it at the level of RTL to
> > ASM.
> > I  know that there is a function (output_asm_insn) in final.c that
> > goes from RTL to ASM.
> > would anyone have any suggestions to do this?
> Yes, it is possible.  However, you are going to have to learn a fair
> amount of gcc infrastructure in order to do it.  One important question
> is going to be how you know which variable you want to duplicate.
> Presumably you don't want to duplicate all variables.  Another important
> question is what you want to do with the duplicated variable.  If you
> duplicate the variable in a straightforward way, the duplicate will
> simply be removed by the optimization passes.
>
> Ian

Whenever I see an unusual request (like this one) I always ask both 
"how", which Ian is answering, but "why".  What are you trying to 
accomplish? Could it be done more simply with other tools?

--jeff