Support for LLVM 16

[athas]

Oclgrind does not seem to support LLVM 16 yet. The first showstopper is that clang has changed the name of the include directory that contains opencl-c.h. From the release notes:

Clang’s resource directory path previously included the full clang version. It now includes only the major version. The new resource directory is $prefix/lib/clang/$CLANG_MAJOR_VERSION and can be queried using clang -print-resource-dir, just like before.

[jrprice]

LLVM 15 isn't yet supported either.

I have WIP changes to migrate to opaque pointers which is the main blocker on upgrading. They're almost done, so I will do my best to find some time in the near future to get that finished off so that we can support LLVM 15 and 16. Sorry for the delays!

[tkanarsky]

Any updates on this? I just tried to take a stab at porting it to LLVM 17 and quickly found myself over my head. In some cases it's pretty trivial to pull the pointee type info from e.g. the owning instr but in your business logic where we're hopping around and dereferencing things, there doesn't seem to be a good way other than keeping an out-of-band mapping from pair<address_space, Value*> -> pointee_type.