This series upgrades the ARB_shader_precision test generator with
support for complex function tolerances.
The ARB_shader_precision spec does not give specific guidance in regard
to acceptable error ranges for complex functions, supplying only the
murky "Built-in functions defined in the specification with an equation
built from the above operations inherit the above errors." Currently,
the shader_precision tests allow zero tolerance for complex functions,
but this is causing many false negatives and needs to be improved.
This series is my best attempt at due diligence - any discussion/input
is certainly welcomed :)
The theory behind this is probably worth a blog post and I won't belabor
the point here, but this series basically implements a filter for the
test_suite dict that will drop any test vectors that would push a
function's output into regions of greatly multiplied error - the
"badlands". If the output does not trespass on the badlands, then the
error estimate in ulps is calculated and attached to the current test
vector for the shader_test to use as the allowable error range when
analyzing the output generated on the GPU during test run-time.
The bigfloat package is a necessary dependency for this filter, as it
provides both arbitrary-size floating point operations and it allows all
floating point values and operations in a code block to be forced into a
particular precision, leaving no question as to what precision was
employed for an intermediate calculation. This comes in handy when
running the reference versions of the complex built-ins. Performance
impact is small (~6s for the entire gen_shader_precision_tests.py script
on IvyBridge i7 @ 2.9GHz) and is localized to build-time.
The technique described above actually takes very little python code to
construct - most of the complexity is in dealing with the polymorphic
nature of the GLSL built-ins - componentwise vs. non-componentwise
parameters, etc.
Micah Fedke (4):
arb_shader_precision: support scalar values in shader_runner_format
arb_shader_precision: add framework for calculating tolerances for
complex functions
arb_shader_precision: add reference implementations of complex functions
arb_shader_precision: enable calculation of complex function tolerances
- update mako templates to support vectors of tolerances
generated_tests/gen_shader_precision_tests.py | 376
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---------
generated_tests/templates/gen_shader_precision_tests/fs.mako | 51
+++++++++++------
generated_tests/templates/gen_shader_precision_tests/gs.mako | 51
+++++++++++------
generated_tests/templates/gen_shader_precision_tests/vs.mako | 51
+++++++++++------
4 files changed, 451 insertions(+), 78 deletions(-)
--
Micah Fedke
Collabora Ltd.
+44 1223 362967
https://www.collabora.com/
https://twitter.com/collaboraltd
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