[Piglit] [PATCH] glsl/frexp: fix the incorrect expected values

[andrey simiklit]

Hello,

Thanks a lot for reviewing.

Regards,
Andrii.

On Fri, Oct 26, 2018 at 3:23 PM Haehnle, Nicolai <Nicolai.Haehnle at amd.com>
wrote:

> On 24.10.18 14:52, asimiklit.work at gmail.com wrote:
> > From: Andrii Simiklit <andrii.simiklit at globallogic.com>
> >
> > I guess that this test has the incorrect expected values.
> > For instance the test expects that exponent for a value 2 will be 1
> > But it contradicts to spec because in this case
> > the value of 'significand' must be 1.0:
> > 2.0 = 1.0 * 2 ^ 1
> >
> > GLSL spec says (about 'frexp'):
> >    "Splits x into a floating-point significand in the range
> >     [0.5, 1.0) and an integral exponent of two, such that:
> >
> >        x = significand * 2 ^ exponent
> >
> >     The significand is returned by the function and the
> >     exponent is returned in the parameter exp. For a
> >     floating-point value of zero, the significant and exponent
> >     are both zero. For a floating-point value that is an
> >     infinity or is not a number, the results are undefined.
>
> You're absolutely right. It seems like radeonsi is currently passing
> this incorrectly, because a bunch of other things surrounding frexp are
> broken.
>
> The test change is correct.
>
> Reviewed-by: Nicolai Hähnle <nicolai.haehnle at amd.com>
>
> >
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108537
> > Signed-off-by: Andrii Simiklit <andrii.simiklit at globallogic.com>
> > ---
> >   .../fs-frexp-dvec4-only-exponent.shader_test        | 13 ++++++++++++-
> >   1 file changed, 12 insertions(+), 1 deletion(-)
> >
> > diff --git
> a/tests/spec/arb_gpu_shader_fp64/execution/built-in-functions/fs-frexp-dvec4-only-exponent.shader_test
> b/tests/spec/arb_gpu_shader_fp64/execution/built-in-functions/fs-frexp-dvec4-only-exponent.shader_test
> > index d7dc64032..c4a7555ff 100644
> > ---
> a/tests/spec/arb_gpu_shader_fp64/execution/built-in-functions/fs-frexp-dvec4-only-exponent.shader_test
> > +++
> b/tests/spec/arb_gpu_shader_fp64/execution/built-in-functions/fs-frexp-dvec4-only-exponent.shader_test
> > @@ -31,7 +31,18 @@ clear color 0 0 0 1
> >   clear
> >
> >   uniform dvec4 u_in 2 3 4 9
> > -uniform ivec4 u_exponent 1 1 2 3
> > +
> > +# The function frexp() splits each single-precision floating-point
> number in
> > +# <x> into a binary significand, a floating-point number in the range
> [0.5,
> > +# 1.0), and an integral exponent of two, such that:
> > +#
> > +#    x = significand * 2 ^ exponent
> > +#
> > +# 2 = 0.5 * 2^2
> > +# 3 = 0.75 * 2^2
> > +# 4 = 0.5 * 2^3
> > +# 9 = 0.5625 * 2^4
> > +uniform ivec4 u_exponent 2 2 3 4
> >
> >   draw rect -1 -1 2 2
> >   probe all rgba 0 1 0 1
> >
>
>
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