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

[andrey simiklit]

Hello,

Could you please help me with a push.

Thanks,
Andrii.

On Fri, Oct 26, 2018 at 5:50 PM andrey simiklit <asimiklit.work at gmail.com>
wrote:

> 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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