I am asking this more in hope than expectation, but would greatly appreciate any help or suggestions (with apologies for a rather lengthy post). The problem I have with my existing OpenCL code is, quite simply, that I am unable to get it to build in Xcode (I have always used Xcode without problems in the past). So my question, quite simply, is:
Can anyone advise how to configure and use Xcode in order to successfully build OpenCL code for Apple Silicon?
Background:
Having just received a shiny new M3 MacBook Pro, I would really like to try out one or two of my GPU programs. They were all written several years using OpenCL, before Apple decided to give up on it in favour of Metal. (In fact, I have since converted one of them to use CUDA, but that is not useful here.) Now, I completely understand that the right thing to do is to convert them to use Metal directly, and will do this when I have time, but I suspect that it will take me several days, if not weeks (I have never had reason to use Metal until now, so I will also have to learn how to convert my code; there are quite a few kernels). I don’t have time to do that at the moment. Meanwhile, I would very much like to try the programs right now, using OpenCL, simply to find out how they run on Apple Silicon (I have previously only used them on older, Intel Macs with AMD GPUs). It would be great to see my code running on the M3’s GPU!
The reasons I think this must still be possible are (a) there are plenty of Geekbench OpenCL results for the M3 chips; and (b) I have managed to compile and run a really trivial OpenCL program (but only using clang from the command line; I have been unable to work out how to compile individual .cl files containing OpenCL kernels).
The problem I am getting is that, having cloned one of my sets of programs into Xcode on my new M3 Mac, I am unable to get any of the kernels even to build. The failure I’m getting is that Xcode is trying to run a version of openclc in the directory /System/Library/Frameworks/OpenCL.framework/Libraries/, which gives the error condition Bad CPU type in executable when Xcode tries to use it. It seems that this is an x86_64 version of openclc. There is a universal binary version in /System/Library/PrivateFrameworks/GPUCompiler.framework/Versions/A/Libraries/, but I have been unable to find a way to configure (or force ….) Xcode to use that one.
It may well be, of course, that if I manage to get past this problem, another one will present itself. Nonetheless, if any of you can suggest anything that I might try, I would be most grateful.
One secondary question, if I may:
Using openclc to compile a .cl file (containing a kernel) from the command line, is there a parameter (e.g. a value to specify with -arch) or combination of parameters that will cause it to produce a .bc file for an Apple Silicon GPU and also the .cl.h header file that has to be #included in the C or C++ code that will dispatch the kernel?
Thanks …. Andrew
PS. I’ve also posted this question on MacRumors, because there seem to be quite a number of people there who understand Apple Silicon, but I rather suspect there’s a better chance of getting getting the help I need here ….
