Re: gcc optimization constant propagation

[John Fine <johnsfine@xxxxxxxxxxx>]

charfi asma wrote:
> Why in the fist code, c is not considered as a constant (in spite that affich() does not change c) 
>
>  
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.

Maybe you want c to be a local variable, so as long as there isn't a 
accessible copy of its address lying around, the compiler can assume it 
isn't modified by code inside called functions.