Addressed comments

Author: grigorypas

llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

@@ -237,7 +237,7 @@ static bool shouldRegisterPGOPasses(const TargetMachine &TM,
     const PGOOptions &Options = *TM.getPGOOption();
     return Options.Action == PGOOptions::PGOAction::IRUse ||
            Options.Action == PGOOptions::PGOAction::SampleUse ||
-           Options.CSAction != PGOOptions::CSPGOAction::CSIRUse;
+           Options.CSAction != PGOOptions::CSPGOAction::NoCSAction;
   }
   return false;
 }

llvm/tools/llc/llc.cpp

@@ -253,13 +253,14 @@ static cl::opt<PGOKind>
                            clEnumValN(SampleUse, "pgo-sample-use-pipeline",
                                       "Use sampled profile to guide PGO.")));
 
-// Function to set PGO options on TargetMachine based on command line flags
+// Function to set PGO options on TargetMachine based on command line flags.
 static void setPGOOptions(TargetMachine &TM) {
   std::optional<PGOOptions> PGOOpt;
 
   switch (PGOKindFlag) {
   case SampleUse:
-    // Use default values for other PGOOptions parameters
+    // Use default values for other PGOOptions parameters. This parameter
+    // is used to test that PGO data is preserved at -O0.
     PGOOpt = PGOOptions("", "", "", "", PGOOptions::SampleUse,
                         PGOOptions::NoCSAction);
     break;