3 files changed, 56 insertions, 6 deletions

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 2a701e04e17..f49d1ef8787 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -3619,7 +3619,7 @@ void CGDebugInfo::EmitFunctionStart(GlobalDecl GD, SourceLocation Loc,
 }
 
 void CGDebugInfo::EmitFunctionDecl(GlobalDecl GD, SourceLocation Loc,
-                                   QualType FnType) {
+                                   QualType FnType, llvm::Function *Fn) {
   StringRef Name;
   StringRef LinkageName;
 
@@ -3629,7 +3629,9 @@ void CGDebugInfo::EmitFunctionDecl(GlobalDecl GD, SourceLocation Loc,
 
   llvm::DINode::DIFlags Flags = llvm::DINode::FlagZero;
   llvm::DIFile *Unit = getOrCreateFile(Loc);
-  llvm::DIScope *FDContext = getDeclContextDescriptor(D);
+  bool IsDeclForCallSite = Fn ? true : false;
+  llvm::DIScope *FDContext =
+      IsDeclForCallSite ? Unit : getDeclContextDescriptor(D);
   llvm::DINodeArray TParamsArray;
   if (isa<FunctionDecl>(D)) {
     // If there is a DISubprogram for this function available then use it.
@@ -3656,10 +3658,38 @@ void CGDebugInfo::EmitFunctionDecl(GlobalDecl GD, SourceLocation Loc,
   if (CGM.getLangOpts().Optimize)
     SPFlags |= llvm::DISubprogram::SPFlagOptimized;
 
-  DBuilder.retainType(DBuilder.createFunction(
+  llvm::DISubprogram *SP = DBuilder.createFunction(
       FDContext, Name, LinkageName, Unit, LineNo,
       getOrCreateFunctionType(D, FnType, Unit), ScopeLine, Flags, SPFlags,
-      TParamsArray.get(), getFunctionDeclaration(D)));
+      TParamsArray.get(), getFunctionDeclaration(D));
+
+  if (IsDeclForCallSite)
+    Fn->setSubprogram(SP);
+
+  DBuilder.retainType(SP);
+}
+
+void CGDebugInfo::EmitFuncDeclForCallSite(llvm::CallBase *CallOrInvoke,
+                                          QualType CalleeType,
+                                          const FunctionDecl *CalleeDecl) {
+  auto &CGOpts = CGM.getCodeGenOpts();
+  if (!CGOpts.EnableDebugEntryValues || !CGM.getLangOpts().Optimize ||
+      !CallOrInvoke ||
+      CGM.getCodeGenOpts().getDebugInfo() < codegenoptions::LimitedDebugInfo)
+    return;
+
+  auto *Func = CallOrInvoke->getCalledFunction();
+  if (!Func)
+    return;
+
+  // If there is no DISubprogram attached to the function being called,
+  // create the one describing the function in order to have complete
+  // call site debug info.
+  if (Func->getSubprogram())
+    return;
+
+  if (!CalleeDecl->isStatic() && !CalleeDecl->isInlined())
+    EmitFunctionDecl(CalleeDecl, CalleeDecl->getLocation(), CalleeType, Func);
 }
 
 void CGDebugInfo::EmitInlineFunctionStart(CGBuilderTy &Builder, GlobalDecl GD) {
diff --git a/clang/lib/CodeGen/CGDebugInfo.h b/clang/lib/CodeGen/CGDebugInfo.h
index e26088a63d0..7edbea86633 100644
--- a/clang/lib/CodeGen/CGDebugInfo.h
+++ b/clang/lib/CodeGen/CGDebugInfo.h
@@ -409,7 +409,15 @@ public:
   void EmitInlineFunctionEnd(CGBuilderTy &Builder);
 
   /// Emit debug info for a function declaration.
-  void EmitFunctionDecl(GlobalDecl GD, SourceLocation Loc, QualType FnType);
+  /// \p Fn is set only when a declaration for a debug call site gets created.
+  void EmitFunctionDecl(GlobalDecl GD, SourceLocation Loc,
+                        QualType FnType, llvm::Function *Fn = nullptr);
+
+  /// Emit debug info for an extern function being called.
+  /// This is needed for call site debug info.
+  void EmitFuncDeclForCallSite(llvm::CallBase *CallOrInvoke,
+                               QualType CalleeType,
+                               const FunctionDecl *CalleeDecl);
 
   /// Constructs the debug code for exiting a function.
   void EmitFunctionEnd(CGBuilderTy &Builder, llvm::Function *Fn);
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index c2330e0844b..abe10d383dc 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -4856,7 +4856,19 @@ RValue CodeGenFunction::EmitCall(QualType CalleeType, const CGCallee &OrigCallee
     Callee.setFunctionPointer(CalleePtr);
   }
 
-  return EmitCall(FnInfo, Callee, ReturnValue, Args, nullptr, E->getExprLoc());
+  llvm::CallBase *CallOrInvoke = nullptr;
+  RValue Call = EmitCall(FnInfo, Callee, ReturnValue, Args, &CallOrInvoke,
+                         E->getExprLoc());
+
+  // Generate function declaration DISuprogram in order to be used
+  // in debug info about call sites.
+  if (CGDebugInfo *DI = getDebugInfo()) {
+    if (auto *CalleeDecl = dyn_cast_or_null<FunctionDecl>(TargetDecl))
+      DI->EmitFuncDeclForCallSite(CallOrInvoke, QualType(FnType, 0),
+                                  CalleeDecl);
+  }
+
+  return Call;
 }
 
 LValue CodeGenFunction::