Re: [PATCH v2] linux-user: Fix clang warning for nios2-linux-user code

[Peter Maydell]

On Tue, 11 Jan 2022 at 09:00, Laurent Vivier <laurent@vivier.eu> wrote:
>
> Le 11/01/2022 à 09:29, Peter Maydell a écrit :
> > The clang in Ubuntu 18.04 (10.0.0-4ubuntu1) produces a warning
> > on the code added in commit f5ef0e518d03 where we use a
> > shifted expression in a boolean context:
> >
> > ../../linux-user/elfload.c:2423:16: error: converting the result of '<<' to 
> > a boolean always evaluates to true [-Werror,-Wtautological-constant-compare]
> >      } else if (LO_COMMPAGE) {
> >                 ^
> > ../../linux-user/elfload.c:1102:22: note: expanded from macro 'LO_COMMPAGE'
> > #define LO_COMMPAGE  TARGET_PAGE_SIZE
> >                       ^
> > /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/include/exec/cpu-all.h:231:31: 
> > note: expanded from macro 'TARGET_PAGE_SIZE'
> > #define TARGET_PAGE_SIZE   (1 << TARGET_PAGE_BITS)
> >                                ^
> > 1 error generated.
> >
> > The warning is bogus because whether LO_COMMPAGE is zero or not
> > depends on compile-time ifdefs; shut the compiler up by adding
> > an explicit comparison to zero.
> >
> > Fixes: f5ef0e518d0331 ("linux-user/nios2: Map a real kuser page")
> > Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> > ---
> > v1->v2: fix sense of comparison (oops!)
> >
> >   linux-user/elfload.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/linux-user/elfload.c b/linux-user/elfload.c
> > index 329b2375ef1..d3274edfdb7 100644
> > --- a/linux-user/elfload.c
> > +++ b/linux-user/elfload.c
> > @@ -2420,7 +2420,7 @@ static void pgb_static(const char *image_name, 
> > abi_ulong orig_loaddr,
> >           } else {
> >               offset = -(HI_COMMPAGE & -align);
> >           }
> > -    } else if (LO_COMMPAGE) {
> > +    } else if (LO_COMMPAGE != 0) {
> >           loaddr = MIN(loaddr, LO_COMMPAGE & -align);
> >       }
> >
>
> Reviewed-by: Laurent Vivier <laurent@vivier.eu>

Thanks; applied to master as a build fix.

-- PMM