[CUDA] Use all 64 bits of GUID in __nv_module_id

[tra]

Summary

getGUID() returns an uint64_t and "%x" only prints 32 bits of it.
Use PRIx64 format string to print all 64 bits.

[Hahnfeld]

LG.

Out of interest: Is this fixing a particular issue?

[tra]

This particular change is largely cosmetic. I've just spotted this nit while I was debugging a different problem.

It's also related to module ID.

We're trying to compile NCCL 2.3 with -fcuda-rdc and we were getting duplicate symbols when we tried to link multiple object files compiled from the same source file.
E.g.

clang++ -DPART1 -o foo-1.o  foo.cu
clang++ -DPART2 -o foo-2.o  foo.cu
...
nvlink ....

The stubs generated by nvlink ended up with conflicting names (based on module ID) that were identical for all foo-*.o.

It appears that clang generates ID based on the source file name only, so all foo-*.o end up with identical ID.
NVCC, on the other hand, appears to generate ID based on some other factors (compiler flags? preprocessed TU source?) so each object file gets a unique ID.

For now we've worked around this by renaming the source files before compilation of each part, but we will need to find a better solution.

cfe/trunk/lib/CodeGen/CGCUDANV.cpp

if (IsHIP) {
 
     // Call __cuda_register_globals(GpuBinaryHandle);
     if (RegisterGlobalsFunc)
       CtorBuilder.CreateCall(RegisterGlobalsFunc, RegisterFatbinCall);
   } else {
     // Generate a unique module ID.
     SmallString<64> ModuleID;
     llvm::raw_svector_ostream OS(ModuleID);
-    OS << ModuleIDPrefix << llvm::format("%x", FatbinWrapper->getGUID());
+    OS << ModuleIDPrefix << llvm::format("%" PRIx64, FatbinWrapper->getGUID());
     llvm::Constant *ModuleIDConstant =
         makeConstantString(ModuleID.str(), "", ModuleIDSectionName, 32);
 
     // Create an alias for the FatbinWrapper that nvcc will look for.
     llvm::GlobalAlias::create(llvm::GlobalValue::ExternalLinkage,
                               Twine("__fatbinwrap") + ModuleID, FatbinWrapper);
 
     // void __cudaRegisterLinkedBinary%ModuleID%(void (*)(void *), void *,