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Re: gcc optimization constant propagation
- From: charfi asma <charfiasma at yahoo dot fr>
- To: gcc-help at gcc dot gnu dot org
- Date: Thu, 5 Mar 2009 10:31:11 +0000 (GMT)
- Subject: Re: gcc optimization constant propagation
> --- En date de : Mer 4.3.09, John Fine <johnsfine@verizon.net>
> a écrit :
>
>
> > I have no idea how deep into affich the compiler can
> look
> > (for changes to c). I expect/hope it looks as
> deep as
> > it inlines.
> >
> > But those operator<<() calls in affich go much
> deeper
> > than you might be thinking through. I expect
> the
> > compiler should not and does not inline that deep, nor
> check
> > for changes to c that deep.
>
> if I change affich() code (I put as an example an
> incrementation of other variable named a) the compiler
> consider c as aconstant (he optimize well and remove all
> switch cases in inc function).
>
> so the problem come from the <<() calls in affich (as
> you expected).
> Is the compiler is lost when he find << calls ?
> (cause a lot of code is generated to affich a string ) so
> that he consider after affich that c is not constant
> although affich did not define c ?? cause if he look even as
> deep as possible (for c changes) he will not find any
> defition or use of c.
>
> thank you for your help.
>
>
>
>