My question is similar to the question "OpenCL - How to I query for a device's SIMD width?", but I'm wondering whether there's any way to do this outside of OpenCL, CUDA, or anything else that's not really available on Android, which I'm targeting. I am writing an OpenGL ES 3.1 application which makes use of compute shaders, and for certain GPGPU algorithms, such as efficient parallel reduction as described by Nvidia (in the Reduction #5 section), there are optimizations you can make if you are aware of the "warp" (a.k.a. wavefront, a.k.a. SIMD width) size of the GPU the code will be running on. I'm also not sure if it's consistent enough on Android GPUs in order to just make a hard-coded assumption without querying anything, or if there's some table of GPU info I can reference, etc.
I tried Googling if there is any way to do this in OpenGL or even in general on Android, but I could not find anything. Is this possible? If not, is there a "recommended" workaround, like just assuming some minimum possible warp size in cases where that still may produce a small speed-up?
For OpenGL ES if the implementation supports the OpenGL ES
KHR_shader_subgroupextension you can useglGetIntegerv(SUBGROUP_SIZE_KHR)to get the subgroup size.https://www.khronos.org/registry/OpenGL/extensions/KHR/KHR_shader_subgroup.txt
For sake of completeness, for Vulkan 1.1 you can query the subgroup size in the device properties
VkPhysicalDeviceSubgroupProperties.subgroupSize.https://www.khronos.org/blog/vulkan-subgroup-tutorial