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Aren't shader programs more like ISPC (or OpenCL/CUDA), in that the programming model is based around 'pretend each SIMD lane is thread'?
by ColonelPhantom 2y ago
Aren't shader programs more like ISPC (or OpenCL/CUDA), in that the programming model is based around 'pretend each SIMD lane is thread'?
- astrange 2y agoDepends on the target architecture. Some GPUs have used vectors in the past, and some people try to run shaders on CPU. (like for OpenCL or for emulation)
- ColonelPhantom 2y ago> Some GPUs have used vectors in the past Which ones? I'm aware of AMD/ATi Terascale using VLIW, but I'm pretty sure that architecture also used SIMD (requiring the use of both VLIW and large 'waves' to achieve maximum occupancy). And running shaders on CPU is, in essence, a similar programming model to ISPC. When you run OpenCL on a CPU I am quite certain that the runtime pretends each lane is a program instance, same as ISPC.