[SampleFDO] Provide a virtual desructor for SampleProfileLoaderBaseImpl

[kazu]

Summary

This patch fixes a warning:

llvm-project/llvm/include/llvm/ProfileData/SampleProfileLoaderBaseImpl.h:69:7:
error: 'llvm::SampleProfileLoaderBaseImpl' has virtual functions but
non-virtual destructor [-Werror,-Wnon-virtual-dtor]

That said, I am not sure who is responsible for freeing:

FunctionSamples *Samples = nullptr;

[xur]

Thanks for fixing this. I think this is fine. I don't think there will a direct allocation of the base type. We always use the derived type to allocate the object.
Samples field will be freed by the Reader which is an uniqe_pointer.

[dblaikie]

Hey, sorry - my commit to fix this (making the dtor protected and default, but non-virtual) collided with this one, so I undid this one in favor of mine. (since the objects don't seem to be owned polymorphically, but concretely such as in llvm/lib/Transforms/IPO/SampleProfile.cpp: SampleProfileLoader SampleLoader;

[xur]

No worry. This fix also works for me. Thank you and Kazu for the quick
response! Much appreciated.

-Rong

llvm/include/llvm/ProfileData/SampleProfileLoaderBaseImpl.h

 extern cl::opt<unsigned> SampleProfileMaxPropagateIterations;
 extern cl::opt<unsigned> SampleProfileRecordCoverage;
 extern cl::opt<unsigned> SampleProfileSampleCoverage;
 extern cl::opt<bool> NoWarnSampleUnused;
 
 class SampleProfileLoaderBaseImpl {
 public:
   SampleProfileLoaderBaseImpl(std::string Name) : Filename(Name) {}
+  virtual ~SampleProfileLoaderBaseImpl() = default;
   void dump() { Reader->dump(); }
 
 protected:
   friend class SampleCoverageTracker;
 
   unsigned getFunctionLoc(Function &F);
   virtual ErrorOr<uint64_t> getInstWeight(const Instruction &Inst);
   ErrorOr<uint64_t> getInstWeightImpl(const Instruction &Inst);