GCC bug ? Re: [PATCH v2 10/10] powerpc/32s: Implement Kernel Userspace Access Protection

[Christophe Leroy]

Le 21/01/2020 à 20:55, Segher Boessenkool a écrit :
> On Tue, Jan 21, 2020 at 05:22:32PM +0000, Christophe Leroy wrote:
>> g1() should return 3, not 5.
> 
> What makes you say that?
> 
> "A return of 0 does not indicate that the
>   value is _not_ a constant, but merely that GCC cannot prove it is a
>   constant with the specified value of the '-O' option."
> 

GCC doc also says:

"if you use it in an inlined function and pass an argument of the 
function as the argument to the built-in, GCC never returns 1 when you 
call the inline function with a string constant"

Does GCC considers (void*)0 as a string constant ?

Christophe