Index: clang/include/clang/Sema/Sema.h
===================================================================
--- clang/include/clang/Sema/Sema.h
+++ clang/include/clang/Sema/Sema.h
@@ -1500,9 +1500,6 @@
   public:
   // Emit all deferred diagnostics.
   void emitDeferredDiags();
-  // Emit any deferred diagnostics for FD and erase them from the map in which
-  // they're stored.
-  void emitDeferredDiags(FunctionDecl *FD, bool ShowCallStack);
 
   enum TUFragmentKind {
     /// The global module fragment, between 'module;' and a module-declaration.
Index: clang/lib/Sema/Sema.cpp
===================================================================
--- clang/lib/Sema/Sema.cpp
+++ clang/lib/Sema/Sema.cpp
@@ -1436,48 +1436,24 @@
 }
 
 // Print notes showing how we can reach FD starting from an a priori
-// known-callable function.
-static void emitCallStackNotes(Sema &S, FunctionDecl *FD) {
+// known-callable function. If \DiagsCount is not null pointer, the number
+// of diagnostics emitted for a function is accumulated.
+static void emitCallStackNotes(Sema &S, FunctionDecl *FD,
+                               llvm::DenseMap<CanonicalDeclPtr<FunctionDecl>,
+                                              unsigned> *DiagsCount = nullptr) {
   auto FnIt = S.DeviceKnownEmittedFns.find(FD);
   while (FnIt != S.DeviceKnownEmittedFns.end()) {
     DiagnosticBuilder Builder(
         S.Diags.Report(FnIt->second.Loc, diag::note_called_by));
     Builder << FnIt->second.FD;
     Builder.setForceEmit();
+    if (DiagsCount)
+      (*DiagsCount)[FnIt->second.FD]++;
 
     FnIt = S.DeviceKnownEmittedFns.find(FnIt->second.FD);
   }
 }
 
-// Emit any deferred diagnostics for FD and erase them from the map in which
-// they're stored.
-void Sema::emitDeferredDiags(FunctionDecl *FD, bool ShowCallStack) {
-  auto It = DeviceDeferredDiags.find(FD);
-  if (It == DeviceDeferredDiags.end())
-    return;
-  bool HasWarningOrError = false;
-  bool FirstDiag = true;
-  for (PartialDiagnosticAt &PDAt : It->second) {
-    const SourceLocation &Loc = PDAt.first;
-    const PartialDiagnostic &PD = PDAt.second;
-    HasWarningOrError |= getDiagnostics().getDiagnosticLevel(
-                             PD.getDiagID(), Loc) >= DiagnosticsEngine::Warning;
-    {
-      DiagnosticBuilder Builder(Diags.Report(Loc, PD.getDiagID()));
-      Builder.setForceEmit();
-      PD.Emit(Builder);
-    }
-
-    // Emit the note on the first diagnostic in case too many diagnostics cause
-    // the note not emitted.
-    if (FirstDiag && HasWarningOrError && ShowCallStack) {
-      emitCallStackNotes(*this, FD);
-      FirstDiag = false;
-    }
-  }
-
-}
-
 namespace {
 /// Helper class that emits deferred diagnostic messages if an entity directly
 /// or indirectly using the function that causes the deferred diagnostic
@@ -1488,6 +1464,10 @@
   typedef UsedDeclVisitor<DeferredDiagnosticsEmitter> Inherited;
   llvm::SmallSet<CanonicalDeclPtr<Decl>, 4> Visited;
   llvm::SmallVector<CanonicalDeclPtr<FunctionDecl>, 4> UseStack;
+
+  // Deferred diagnostics triggered by a declaration.
+  llvm::DenseMap<CanonicalDeclPtr<FunctionDecl>, unsigned> DiagsCount;
+
   bool ShouldEmit;
   unsigned InOMPDeviceContext;
 
@@ -1509,6 +1489,8 @@
 
   void visitUsedDecl(SourceLocation Loc, Decl *D) {
     if (auto *FD = dyn_cast<FunctionDecl>(D)) {
+
+      auto DiagsCountIt = DiagsCount.find(FD);
       FunctionDecl *Caller = UseStack.empty() ? nullptr : UseStack.back();
       auto IsKnownEmitted = S.getEmissionStatus(FD, /*Final=*/true) ==
                             Sema::FunctionEmissionStatus::Emitted;
@@ -1520,10 +1502,15 @@
       // Finalize analysis of OpenMP-specific constructs.
       if (Caller && S.LangOpts.OpenMP && UseStack.size() == 1)
         S.finalizeOpenMPDelayedAnalysis(Caller, FD, Loc);
+      else if (DiagsCountIt != DiagsCount.end() && DiagsCountIt->second == 0 &&
+               !InOMPDeviceContext)
+        return;
+      if (DiagsCountIt == DiagsCount.end())
+        DiagsCount[FD] = 0;
       if (Caller)
         S.DeviceKnownEmittedFns[FD] = {Caller, Loc};
       if (ShouldEmit || InOMPDeviceContext)
-        S.emitDeferredDiags(FD, Caller);
+        emitDeferredDiags(FD, Caller);
       Visited.insert(D);
       UseStack.push_back(FD);
       if (auto *S = FD->getBody()) {
@@ -1551,6 +1538,35 @@
     } else
       Inherited::visitUsedDecl(Loc, D);
   }
+
+  // Emit any deferred diagnostics for FD
+  void emitDeferredDiags(FunctionDecl *FD, bool ShowCallStack) {
+    auto It = S.DeviceDeferredDiags.find(FD);
+    if (It == S.DeviceDeferredDiags.end())
+      return;
+    bool HasWarningOrError = false;
+    bool FirstDiag = true;
+    for (PartialDiagnosticAt &PDAt : It->second) {
+      const SourceLocation &Loc = PDAt.first;
+      const PartialDiagnostic &PD = PDAt.second;
+      HasWarningOrError |=
+          S.getDiagnostics().getDiagnosticLevel(PD.getDiagID(), Loc) >=
+          DiagnosticsEngine::Warning;
+      {
+        DiagnosticBuilder Builder(S.Diags.Report(Loc, PD.getDiagID()));
+        Builder.setForceEmit();
+        PD.Emit(Builder);
+      }
+
+      DiagsCount[FD]++;
+      // Emit the note on the first diagnostic in case too many diagnostics
+      // cause the note not emitted.
+      if (FirstDiag && HasWarningOrError && ShowCallStack) {
+        emitCallStackNotes(S, FD, &DiagsCount);
+        FirstDiag = false;
+      }
+    }
+  }
 };
 } // namespace