Re: unoptimized dead store

[Jim Kingdon <jkingdon@xxxxxxxxxxxxxxxxxxxx>]

Looks interprocedural to me.  The optimization
is only possible if the compiler knows that
the "glarp" function does not modify "a".

(Look up "alias" in a compiler text, "restrict"
in C99, similar rules for Fortran, &c).

stuart@xxxxxxxxx wrote:

> Clueless newbie here.
> 
> Here's my test program:
> ----------------------
> int a, b ;
> 
> main( int xx)
> {
>    a = 2 ;
>    glarp( xx) ;
>    a++ ;
>    return a + b ;
> }
> glarp( int j)
> {
>    extern int a ;
> 
>    if (j < 10)
>      bling( j-1) ;
> }
> 
> bling( int k)
> {
>    extern int b ;
> 
>    b = k ;
> }