[Piglit] [PATCH 2/2] arb_shader_image_load_store/invalid: Skip the index bounds test on Intel Ivybridge hardware.

[Francisco Jerez]

Jordan Justen <jordan.l.justen at intel.com> writes:

> I don't know of any other cases where we skip a test based on the
> render name. I don't think this is a good practice to start.
>

What do you think we should do in that case?

> -Jordan
>
> On 2015-07-24 11:01:47, Francisco Jerez wrote:
>> This test is known to cause a GPU hang on IVB due to a hardware bug.
>> The reason is that the hardware seems to be unable to cope with
>> binding table indices mapping to an invalid surface, which is
>> sometimes the case when a shader accesses an array of images out of
>> bounds.
>> 
>> According to the ARB_shader_image_load_store spec "if the index used
>> to select an individual element [of an array of images] is negative or
>> greater than or equal to the size of the array, the results of the
>> operation are undefined but may not lead to termination." -- Which is
>> precisely one of the typical outcomes of the GPU hang caused by this
>> test.
>> 
>> In theory this could be fixed by implementing array bounds checking in
>> software, but it doesn't seem worth doing because on the one hand it
>> would punish well-behaved applications unnecessarily, and on the other
>> hand there doesn't seem to be any reasonable use-case for the
>> behaviour required by the spec [the implementation may set the
>> computer on fire as long as it somehow manages not to terminate the
>> program ;)].
>> 
>> If the breakage caused by this test case was confined to a single
>> process I would probably consider to leave it alone, however I've
>> noticed that in some cases the hang will cause other unrelated piglit
>> tests that happen to be run in parallel to fail, causing some random
>> noise in the results we get from our piglit system, what makes them
>> rather difficult to interpret.
>> ---
>>  tests/spec/arb_shader_image_load_store/invalid.c | 13 ++++++++++++-
>>  1 file changed, 12 insertions(+), 1 deletion(-)
>> 
>> diff --git a/tests/spec/arb_shader_image_load_store/invalid.c b/tests/spec/arb_shader_image_load_store/invalid.c
>> index a0981e4..52b3275 100644
>> --- a/tests/spec/arb_shader_image_load_store/invalid.c
>> +++ b/tests/spec/arb_shader_image_load_store/invalid.c
>> @@ -292,6 +292,17 @@ invalidate_address_bounds(const struct image_info img, GLuint prog)
>>  }
>>  
>>  static bool
>> +can_test_index_bounds(void)
>> +{
>> +   /* This test is known to cause a GPU hang on Intel Ivybridge
>> +    * hardware due to a hardware bug.  Don't annoy users
>> +    * unnecessarily.
>> +    */
>> +   return !strstr((const char *)glGetString(GL_RENDERER),
>> +                  "Intel(R) Ivybridge");
>> +}
>> +
>> +static bool
>>  invalidate_index_bounds(const struct image_info img, GLuint prog)
>>  {
>>          return set_uniform_int(prog, "u", 0xdeadcafe);
>> @@ -444,7 +455,7 @@ piglit_init(int argc, char **argv)
>>                   *  element is negative or greater than or equal to
>>                   *  the size of the array [...]"
>>                   */
>> -                subtest(&status, true,
>> +                subtest(&status, can_test_index_bounds(),
>>                          run_test(op, def_img, def_img,
>>                                   invalidate_index_bounds, true),
>>                          "%s/index bounds test", op->name);
>> -- 
>> 2.4.3
>> 
>> _______________________________________________
>> Piglit mailing list
>> Piglit at lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/piglit
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