[Polly] [PPCGCodeGeneration] Print current Scop and loop depth in PPCGCodeGen. [NFC]

[bollu]

Summary

This is useful to see what's going on when PPCGCodeGen is running.

[grosser]

LGTM.

polly/trunk/lib/CodeGen/PPCGCodeGeneration.cpp

public:
   bool runOnScop(Scop &CurrentScop) override {
     S = &CurrentScop;
     LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
     DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
     SE = &getAnalysis<ScalarEvolutionWrapperPass>().getSE();
     DL = &S->getRegion().getEntry()->getModule()->getDataLayout();
     RI = &getAnalysis<RegionInfoPass>().getRegionInfo();
 
+    DEBUG(dbgs() << "PPCGCodeGen running on : " << getUniqueScopName(S)
+                 << " | loop depth: " << S->getMaxLoopDepth() << "\n");
+
     // We currently do not support functions other than intrinsics inside
     // kernels, as code generation will need to offload function calls to the
     // kernel. This may lead to a kernel trying to call a function on the host.
     // This also allows us to prevent codegen from trying to take the
     // address of an intrinsic function to send to the kernel.
     if (containsInvalidKernelFunction(CurrentScop,
                                       Architecture == GPUArch::NVPTX64)) {
       DEBUG(