Strongly disagree - the fact that GPU ISA is undocumented let GPU vendors to innovate faster, and let them modify ISA not only between models, but also inside t

Strongly disagree - the fact that GPU ISA is undocumented let GPU vendors to innovate faster, and let them modify ISA not only between models, but also inside the same architecture family. For NVIDIA only documented PTX, while actual ISA is changed frequently. Same with AMD: CAL is documented, but the actual low-level ISA can change. For example recently they moved from VLIW5 to VLIW4. I also think, that reliance on hard ISA (x86 or ARM) in modern server-desktop-mobile world is doing more harm, than good. Today there are just too many layers/levels, for example in NVIDIA: CUDA -> LLVM -> PTX -> native ISA CUDA -> LLVM -> x86 -> Intel Microcode OpenCL -> CUDA -> LLVM -> PTX -> native ISA OpenCL -> CUDA -> LLVM -> x86 -> Intel Microcode or in AMD: OpenCL -> LLVM -> CAL -> native ISA OpenCL -> LLVM -> x86 -> AMD Microcode The C was that kind of universal ISA in the RISC UNIX world. But C can't express Vectorization and SIMD efficiently and in platform independent way. Enter OpenCL!