[PGO] Don't cross reference CSFDO profile and non-CSFDO profile

[xur]

Summary

Don't cross reference CSFDO profile and non-CSFDO profile when
checking the function hash. Only return hash_mismatch when
CS bits match, and return unknown_function otherwise.

[davidxl]

lgtm

llvm/lib/ProfileData/InstrProfReader.cpp

 Expected<InstrProfRecord>
 IndexedInstrProfReader::getInstrProfRecord(StringRef FuncName,
                                            uint64_t FuncHash) {
   ArrayRef<NamedInstrProfRecord> Data;
   Error Err = Remapper->getRecords(FuncName, Data);
   if (Err)
     return std::move(Err);
   // Found it. Look for counters with the right hash.
+
+  // A flag to indicate if the records are from the same type
+  // of profile (i.e cs vs nocs).
+  bool CSBitMatch = false;
+
   for (const NamedInstrProfRecord &I : Data) {
     // Check for a match and fill the vector if there is one.
     if (I.Hash == FuncHash)
       return std::move(I);
+    if (NamedInstrProfRecord::hasCSFlagInHash(I.Hash) ==
+        NamedInstrProfRecord::hasCSFlagInHash(FuncHash)) {
+      CSBitMatch = true;
     }
+  }
+  if (CSBitMatch) {
     return error(instrprof_error::hash_mismatch);
   }
+  return error(instrprof_error::unknown_function);
+}
 
 Expected<memprof::MemProfRecord>
 IndexedInstrProfReader::getMemProfRecord(const uint64_t FuncNameHash) {
   // TODO: Add memprof specific errors.
   if (MemProfRecordTable == nullptr)
     return make_error<InstrProfError>(instrprof_error::invalid_prof,
                                       "no memprof data available in profile");
   auto Iter = MemProfRecordTable->find(FuncNameHash);

llvm/test/Transforms/PGOProfile/Inputs/cs_vs_nocs.proftext

+# CSIR level Instrumentation Flag
+:csir
+bar
+# Func Hash:
+1895182923573755903
+# Num Counters:
+1
+# Counter Values:
+100000
+

llvm/test/Transforms/PGOProfile/diag_no_funcprofdata_cs.ll

+; RUN: llvm-profdata merge %S/Inputs/cs_vs_nocs.proftext -o %t.profdata
+; RUN: opt < %s -passes=pgo-instr-use -pgo-warn-missing-function=true -pgo-test-profile-file=%t.profdata -S 2>&1 | FileCheck %s
+
+; CHECK: warning: {{.+}}: no profile data available for function bar
+; CHECK-NOT: warning: {{.+}}: function control flow change detected (hash mismatch)
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define i32 @bar() {
+entry:
+  ret i32 0
+}