I invite anyone who thinks C is low level to try their hand at CUDA or OpenCL.
You think C is bad? Those are far worse.
This is at least a great step in the right direction. It's not "low level" as you describe just because it's C.
You think C is bad? Those are far worse.
This is at least a great step in the right direction. It's not "low level" as you describe just because it's C.
I read a lot of GPGPU papers at the university, and I could never understand the older ones, that described algorithms by mapping everything to graphics elements, and computed the solutions as a side-effect of rendering something.
Next to that, undestanding an algorithm implemented in CUDA is a breeze.
CUDA and OpenCL demand a depth of understanding of both C, and how your code is executed on many core processors. but i wouldn't call either of them terrible.
i would however, very much like to see a widespread higher level API for doing compute on GPUs, if only to encourage people to understand the lower level details.
The reason it is that it operates on concepts that are not abstract but are of register machines. A high completely abstracts underlying architecture so the code can be executed in any possible environment by means of translation, be it a $10MM Cray or a cellular automaton or a mechanical computer. In essence, a high level language provides an abstract notation for computation.
C, however, is not abstract at all. Variables? How those will map to a dataflow computation? Pointers? Would not work beyond register CPUs (e.g. it is very cumbersome to translate C programs to Javascript as a result and usually leads to a memory array emulation). Fixed-width types? Volatile pointers? Returns from the middle of a procedure? Gotos? Come on, how those are even going to run on a non-conventional architecture?
C also does not completely define the language semantics leaving certain operations implementation-specific or undefined. It also (before C11) didn't define any memory model, thus making it impossible to even describe an algorithm that depends on specific properties of memory accesses in a way that will be portable across different register machines. C algorithms are close to impossible to translate to be run on memory-less computation devices as the whole concept of C is based around having local memory and a stack space with certain properties (unless one wants to emulate a register machine, see JavaScript remark above).
In certain areas it lead to some ugly solutions like Cuda where the language looks like C but semantics is completely different and GPUs are the closest thing to he original C target as you can get.