[Mesa-dev] [PATCH] vl/zscan: fix "Fix trivial sign compare warnings"

[Jan Vesely]

On Wed, 2016-12-14 at 17:46 +0000, Emil Velikov wrote:
> On 14 December 2016 at 14:07, Christian König <deathsimple at vodafone.de> wrote:
> > From: Christian König <christian.koenig at amd.com>
> > 
> > The variable actually needs to be signed, otherwise converting it to a
> > float doesn't work as expected.
> > 
> > Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=98914
> > Signed-off-by: Christian König <christian.koenig at amd.com>
> > ---
> >  src/gallium/auxiliary/vl/vl_zscan.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/src/gallium/auxiliary/vl/vl_zscan.c b/src/gallium/auxiliary/vl/vl_zscan.c
> > index ef05af4..24d6452 100644
> > --- a/src/gallium/auxiliary/vl/vl_zscan.c
> > +++ b/src/gallium/auxiliary/vl/vl_zscan.c
> > @@ -152,7 +152,7 @@ create_vert_shader(struct vl_zscan *zscan)
> >     for (i = 0; i < zscan->num_channels; ++i) {
> >        ureg_ADD(shader, ureg_writemask(tmp, TGSI_WRITEMASK_X), ureg_scalar(ureg_src(tmp), TGSI_SWIZZLE_Y),
> >                 ureg_imm1f(shader, 1.0f / (zscan->blocks_per_line * VL_BLOCK_WIDTH)
> > -                * (i - (signed)zscan->num_channels / 2)));
> > +                * ((signed)i - (signed)zscan->num_channels / 2)));
> > 
> 
> Nice one Christian. And apologies for missing this during review.

oh, that's a subtle one. my apologies.

> 
> I think we want to address the other regressions introduced with
> 1fb4179f927442354f93dfc8494f0236e50af838.
> Namely: most of the increment_addr() users in vl_idct.c will need a
> cast as well.

the function takes int argument that converts it back and hides the
error, but reverting the change in that file is probably better.


Jan

> 
> Please add the following tags.
> 
> Cc: "13.0" <mesa-stable at lists.freedesktop.org>
> Fixes: 1fb4179f927 ("vl: Fix trivial sign compare warnings")
> 
> Thanks
> -Emil
> 
> P.S. For anyone wondering, feel free to look at the implicit
> conversion and promotion parts in C[1]
> [1] http://stackoverflow.com/a/2280810
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