Here's a quick example:
//// GPUTHREADS.EPOCH//// This program demonstrates running threaded computations on the GPU,// courtesy of CUDA. A thread is created for each logical CPU core in// the host machine, and the computations are run on both the CPU and// GPU, using as many threads as possible in the GPU case.//// Note that both the GPU and CPU threaded functions invoke the same// Epoch source code; there is no need to explicitly write the GPU-side// code in another language, as the JIT cross-compiler will take care// of generating the appropriate CUDA code for execution on the GPU.//extension("EpochCUDA")//// Win32 API access//structure SystemInfoType :( integer16(architecture), integer16(reserved), integer(pagesize), integer(minappaddress), integer(maxappaddress), integer(activeprocmask), integer(numprocessors), integer(proctype), integer(allocgranularity), integer16(proclevel), integer16(procrevision))external "kernel32.dll" GetSystemInfo : (SystemInfoType ref(info)) -> ()external "winmm.dll" timeGetTime : () -> (integer)//// Program entry point; execution begins here//entrypoint : () -> (){ integer(cpucount, GetCPUCount()) if(cpucount <= 0) { debugwritestring("Failed to determine number of logical CPUs available!") return() } if(!IsCUDAAvailable()) { debugwritestring("WARNING: No CUDA-capable hardware found!") debugwritestring("Code targeted for CUDA will run on the CPU instead") debugwritestring("") } debugwritestring("Generating test data...") array(input1, CUDAGenerateDataArray()) array(input2, CUDAGenerateDataArray()) array(output, CUDAGenerateEmptyArray()) debugwritestring("Computation batch, CPU, " ; cast(string, cpucount) ; " threads (1 per core), " ; cast(string, length(input1)) ; " elements:") integer(starttime, 0) integer(finishtime, 0) real(elapsedtime, 0.0) starttime = timeGetTime() parallelfor(i, 0, length(input1), cpucount) { compute(i, input1, input2, output) } finishtime = timeGetTime() elapsedtime = cast(real, finishtime - starttime) / 1000.0 debugwritestring(cast(string, elapsedtime) ; " seconds") debugwritestring("Computation batch, CUDA, " ; cast(string, length(input1)) ; " elements:") starttime = timeGetTime() cudafor(i, 0, length(input1)) { compute(i, input1, input2, output) } finishtime = timeGetTime() elapsedtime = cast(real, finishtime - starttime) / 1000.0 debugwritestring(cast(string, elapsedtime) ; " seconds")}//// Actual worker kernel function; doesn't do much, just runs some throw-away calculations//compute : (integer(index), real array(input1), real array(input2), real array ref(output)) -> (integer(result, 0)){ writearray(output, index, readarray(input1, index) + readarray(input2, index))}//// Helper for getting the logical number of CPUs on the host machine//GetCPUCount : () -> (integer(retval, 0)){ SystemInfoType(info, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) GetSystemInfo(info) retval = info.numprocessors}Aside from the user-friendly "CUDA isn't available" warning, this program does nothing related to checking for GPGPU support. The EpochCUDA extension library simply reports that it is not willing to execute code, so the virtual machine just runs the appropriate stuff directly on the CPU. The cudafor construct basically decays into a regular parallelfor and runs on the CPU, should adequate hardware not be available.
I'd ramble more about the cool goodies coming up in R9, but frankly my brain is totally shot, and I need to get some sleep.
I'm down to 4 remaining tasks before I can package and ship R9, plus a hefty dose of TODO comments sprinkled around the code, so there's no shortage of work left to do. On the plus side, the absolutely-mandatory jobs are all small and quick, and I can just whittle away at the TODO list as I get spare time before GDC.
Haha, spare time. Me make funny joke.
Very nifty. I really have to look into Cuda in more detail when I have some spare time [smile]
My main point of wonder is how you manage to get that compute code to run on the GPU transparently. Do you emit that to Cuda instructions at build/interpretation time or is this something facilitated by Cuda itself?