Index: compiler-rt/trunk/lib/profile/InstrProfData.inc
===================================================================
--- compiler-rt/trunk/lib/profile/InstrProfData.inc
+++ compiler-rt/trunk/lib/profile/InstrProfData.inc
@@ -169,7 +169,7 @@
 
 /* VALUE_PROF_KIND start */
 #ifndef VALUE_PROF_KIND
-#define VALUE_PROF_KIND(Enumerator, Value)
+#define VALUE_PROF_KIND(Enumerator, Value, Descr)
 #else
 #define INSTR_PROF_DATA_DEFINED
 #endif
@@ -182,16 +182,16 @@
  * For this remapping the ProfData is used.  ProfData contains both the function
  * name hash and the function address.
  */
-VALUE_PROF_KIND(IPVK_IndirectCallTarget, 0)
+VALUE_PROF_KIND(IPVK_IndirectCallTarget, 0, "indirect call target")
 /* For memory intrinsic functions size profiling. */
-VALUE_PROF_KIND(IPVK_MemOPSize, 1)
+VALUE_PROF_KIND(IPVK_MemOPSize, 1, "memory intrinsic functions size")
 /* These two kinds must be the last to be
  * declared. This is to make sure the string
  * array created with the template can be
  * indexed with the kind value.
  */
-VALUE_PROF_KIND(IPVK_First, IPVK_IndirectCallTarget)
-VALUE_PROF_KIND(IPVK_Last, IPVK_MemOPSize)
+VALUE_PROF_KIND(IPVK_First, IPVK_IndirectCallTarget, "first")
+VALUE_PROF_KIND(IPVK_Last, IPVK_MemOPSize, "last")
 
 #undef VALUE_PROF_KIND
 /* VALUE_PROF_KIND end */
Index: compiler-rt/trunk/lib/profile/InstrProfiling.h
===================================================================
--- compiler-rt/trunk/lib/profile/InstrProfiling.h
+++ compiler-rt/trunk/lib/profile/InstrProfiling.h
@@ -15,7 +15,7 @@
 #include "InstrProfData.inc"
 
 enum ValueKind {
-#define VALUE_PROF_KIND(Enumerator, Value) Enumerator = Value,
+#define VALUE_PROF_KIND(Enumerator, Value, Descr) Enumerator = Value,
 #include "InstrProfData.inc"
 };
 
Index: llvm/trunk/include/llvm/ProfileData/InstrProf.h
===================================================================
--- llvm/trunk/include/llvm/ProfileData/InstrProf.h
+++ llvm/trunk/include/llvm/ProfileData/InstrProf.h
@@ -234,7 +234,7 @@
 bool canRenameComdatFunc(const Function &F, bool CheckAddressTaken = false);
 
 enum InstrProfValueKind : uint32_t {
-#define VALUE_PROF_KIND(Enumerator, Value) Enumerator = Value,
+#define VALUE_PROF_KIND(Enumerator, Value, Descr) Enumerator = Value,
 #include "llvm/ProfileData/InstrProfData.inc"
 };
 
Index: llvm/trunk/include/llvm/ProfileData/InstrProfData.inc
===================================================================
--- llvm/trunk/include/llvm/ProfileData/InstrProfData.inc
+++ llvm/trunk/include/llvm/ProfileData/InstrProfData.inc
@@ -169,7 +169,7 @@
 
 /* VALUE_PROF_KIND start */
 #ifndef VALUE_PROF_KIND
-#define VALUE_PROF_KIND(Enumerator, Value)
+#define VALUE_PROF_KIND(Enumerator, Value, Descr)
 #else
 #define INSTR_PROF_DATA_DEFINED
 #endif
@@ -182,16 +182,16 @@
  * For this remapping the ProfData is used.  ProfData contains both the function
  * name hash and the function address.
  */
-VALUE_PROF_KIND(IPVK_IndirectCallTarget, 0)
+VALUE_PROF_KIND(IPVK_IndirectCallTarget, 0, "indirect call target")
 /* For memory intrinsic functions size profiling. */
-VALUE_PROF_KIND(IPVK_MemOPSize, 1)
+VALUE_PROF_KIND(IPVK_MemOPSize, 1, "memory intrinsic functions size")
 /* These two kinds must be the last to be
  * declared. This is to make sure the string
  * array created with the template can be
  * indexed with the kind value.
  */
-VALUE_PROF_KIND(IPVK_First, IPVK_IndirectCallTarget)
-VALUE_PROF_KIND(IPVK_Last, IPVK_MemOPSize)
+VALUE_PROF_KIND(IPVK_First, IPVK_IndirectCallTarget, "first")
+VALUE_PROF_KIND(IPVK_Last, IPVK_MemOPSize, "last")
 
 #undef VALUE_PROF_KIND
 /* VALUE_PROF_KIND end */
Index: llvm/trunk/lib/ProfileData/InstrProfWriter.cpp
===================================================================
--- llvm/trunk/lib/ProfileData/InstrProfWriter.cpp
+++ llvm/trunk/lib/ProfileData/InstrProfWriter.cpp
@@ -357,7 +357,7 @@
 }
 
 static const char *ValueProfKindStr[] = {
-#define VALUE_PROF_KIND(Enumerator, Value) #Enumerator,
+#define VALUE_PROF_KIND(Enumerator, Value, Descr) #Enumerator,
 #include "llvm/ProfileData/InstrProfData.inc"
 };
 
Index: llvm/trunk/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
+++ llvm/trunk/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
@@ -1426,8 +1426,14 @@
     annotateValueSites(Kind);
 }
 
+static const char *ValueProfKindDescr[] = {
+#define VALUE_PROF_KIND(Enumerator, Value, Descr) Descr,
+#include "llvm/ProfileData/InstrProfData.inc"
+};
+
 // Annotate the instructions for a specific value kind.
 void PGOUseFunc::annotateValueSites(uint32_t Kind) {
+  assert(Kind <= IPVK_Last);
   unsigned ValueSiteIndex = 0;
   auto &ValueSites = FuncInfo.ValueSites[Kind];
   unsigned NumValueSites = ProfileRecord.getNumValueSites(Kind);
@@ -1435,8 +1441,10 @@
     auto &Ctx = M->getContext();
     Ctx.diagnose(DiagnosticInfoPGOProfile(
         M->getName().data(),
-        Twine("Inconsistent number of value sites for kind = ") + Twine(Kind) +
-            " in " + F.getName().str(),
+        Twine("Inconsistent number of value sites for ") +
+            Twine(ValueProfKindDescr[Kind]) +
+            Twine(" profiling in \"") + F.getName().str() +
+            Twine("\", possibly due to the use of a stale profile."),
         DS_Warning));
     return;
   }
Index: llvm/trunk/test/Transforms/PGOProfile/Inputs/diag_no_value_sites.proftext
===================================================================
--- llvm/trunk/test/Transforms/PGOProfile/Inputs/diag_no_value_sites.proftext
+++ llvm/trunk/test/Transforms/PGOProfile/Inputs/diag_no_value_sites.proftext
@@ -0,0 +1,6 @@
+# :ir is the flag to indicate this is IR level profile.
+:ir
+foo
+12884901887
+1
+1
Index: llvm/trunk/test/Transforms/PGOProfile/diag_no_value_sites.ll
===================================================================
--- llvm/trunk/test/Transforms/PGOProfile/diag_no_value_sites.ll
+++ llvm/trunk/test/Transforms/PGOProfile/diag_no_value_sites.ll
@@ -0,0 +1,15 @@
+; RUN: llvm-profdata merge %S/Inputs/diag_no_value_sites.proftext -o %t.profdata
+; RUN: opt < %s -pgo-instr-use -pgo-test-profile-file=%t.profdata -S 2>&1 | FileCheck %s
+
+; CHECK: Inconsistent number of value sites for memory intrinsic functions size profiling
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @foo(i8* %dst, i8* %src, i64 %n) {
+entry:
+  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %src, i64 %n, i1 false)
+  ret void
+}
+
+declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture writeonly, i8* nocapture readonly, i64, i1)