One of the greatest features from piglit was the easy development of OpenGL tests based on GLSL shaders plus some simple commands through shader_runner command. I even wrote about it.
However, Vulkan ecosystem was missing a tool like that but for SPIR-V shader tests… until last year!
VkRunner is a tool written by Neil Roberts, which is very inspired on shader_runner. VkRunner was the result of the Igalia work to enable ARB_gl_spirv extension for Intel’s i965 driver on Mesa, where there was a need to test driver’s code against a good number of shaders to be sure that it was fine.
VkRunner uses a script language to define the requirements needed to run the test, such as the needed extension and features, the shaders to be run and a series of commands to run it. It will then parse everything and execute the equivalent Vulkan commands to do so under the hood, like shader_runner did for OpenGL in piglit.
This is an example of how a Vkrunner looks like:
[compute shader]
#version 450
layout(std140, push_constant) uniform push_constants {
float in_value;
};
layout(std140, binding = 0) buffer ssbo {
float out_value;
};
void
main()
{
out_value = sqrt(in_value);
}
[test]
# Allocate an ssbo big enough for a float at binding 0
ssbo 0 4
# Set the push constant as an input value
uniform float 0 4
compute 1 1 1
# Probe that we got the expected value
tolerance 0.00006% 0.00006% 0.00006% 0.00006%
probe ssbo float 0 0 ~= 2
The end of 2018 was great for VkRunner! First, the tool was integrated into piglit so we can now use it in this amazing open-source testing suite for 3D graphics drivers. Soon after, it was integrated into Khronos Group’s Vulkan and OpenGL Conformance Test Suite (see commit), which will help contributors to easily write SPIR-V tests on Vulkan.
If you want learn more about VkRunner, apart from browsing the repository, Neil wrote a nice blogpost explaining the tool basics, gave a lightning talk at XDC 2018 (slides) in A Coruña and now, he is going to give a talk in the graphics devroom at FOSDEM 2019! You can follow his FOSDEM talk on Saturday via live-stream (or see the recording afterwards) in case you are not going to FOSDEM this year :-)
