[lldb] Make GetSelectedOrDummyTarget return the target by reference (NFC)

Return references from GetDummyTarget and GetSelectedOrDummyTarget. This
matches how the APIs are already used in practice.

lldb/include/lldb/Core/Debugger.h

@@ -334,8 +334,8 @@ public:
   // This is for use in the command interpreter, when you either want the
   // selected target, or if no target is present you want to prime the dummy
   // target with entities that will be copied over to new targets.
-  Target *GetSelectedOrDummyTarget(bool prefer_dummy = false);
-  Target *GetDummyTarget() { return m_dummy_target_sp.get(); }
+  Target &GetSelectedOrDummyTarget(bool prefer_dummy = false);
+  Target &GetDummyTarget() { return *m_dummy_target_sp; }
 
   lldb::BroadcasterManagerSP GetBroadcasterManager() {
     return m_broadcaster_manager_sp;

lldb/include/lldb/Target/Target.h

@@ -212,7 +212,7 @@ public:
   bool GetInjectLocalVariables(ExecutionContext *exe_ctx) const;
 
   void SetInjectLocalVariables(ExecutionContext *exe_ctx, bool b);
-  
+
   void SetRequireHardwareBreakpoints(bool b);
 
   bool GetRequireHardwareBreakpoints() const;
@@ -1252,7 +1252,7 @@ public:
     StructuredDataImpl *m_extra_args; // We own this structured data,
                                       // but the SD itself manages the UP.
     /// This holds the python callback object.
-    StructuredData::GenericSP m_implementation_sp; 
+    StructuredData::GenericSP m_implementation_sp;
 
     /// Use CreateStopHook to make a new empty stop hook. The GetCommandPointer
     /// and fill it with commands, and SetSpecifier to set the specifier shared
@@ -1374,12 +1374,12 @@ protected:
   lldb::PlatformSP m_platform_sp; ///< The platform for this target.
   std::recursive_mutex m_mutex; ///< An API mutex that is used by the lldb::SB*
                                 /// classes make the SB interface thread safe
-  /// When the private state thread calls SB API's - usually because it is 
+  /// When the private state thread calls SB API's - usually because it is
   /// running OS plugin or Python ThreadPlan code - it should not block on the
   /// API mutex that is held by the code that kicked off the sequence of events
-  /// that led us to run the code.  We hand out this mutex instead when we 
+  /// that led us to run the code.  We hand out this mutex instead when we
   /// detect that code is running on the private state thread.
-  std::recursive_mutex m_private_mutex; 
+  std::recursive_mutex m_private_mutex;
   Arch m_arch;
   ModuleList m_images; ///< The list of images for this process (shared
                        /// libraries and anything dynamically loaded).
@@ -1458,7 +1458,7 @@ private:
   bool ProcessIsValid();
 
   // Copy breakpoints, stop hooks and so forth from the dummy target:
-  void PrimeFromDummyTarget(Target *dummy_target);
+  void PrimeFromDummyTarget(Target &target);
 
   void AddBreakpoint(lldb::BreakpointSP breakpoint_sp, bool internal);
 

lldb/source/API/SBDebugger.cpp

@@ -858,7 +858,7 @@ SBTarget SBDebugger::GetDummyTarget() {
 
   SBTarget sb_target;
   if (m_opaque_sp) {
-    sb_target.SetSP(m_opaque_sp->GetDummyTarget()->shared_from_this());
+    sb_target.SetSP(m_opaque_sp->GetDummyTarget().shared_from_this());
   }
   Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_API));
   LLDB_LOGF(log, "SBDebugger(%p)::GetDummyTarget() => SBTarget(%p)",

lldb/source/Commands/CommandObjectExpression.cpp

@@ -304,11 +304,8 @@ void CommandObjectExpression::HandleCompletion(CompletionRequest &request) {
     return;
 
   ExecutionContext exe_ctx(m_interpreter.GetExecutionContext());
-
-  Target *target = exe_ctx.GetTargetPtr();
-
-  if (!target)
-    target = &GetDummyTarget();
+  Target *exe_target = exe_ctx.GetTargetPtr();
+  Target &target = exe_target ? *exe_target : GetDummyTarget();
 
   unsigned cursor_pos = request.GetRawCursorPos();
   // Get the full user input including the suffix. The suffix is necessary
@@ -342,7 +339,7 @@ void CommandObjectExpression::HandleCompletion(CompletionRequest &request) {
   auto language = exe_ctx.GetFrameRef().GetLanguage();
 
   Status error;
-  lldb::UserExpressionSP expr(target->GetUserExpressionForLanguage(
+  lldb::UserExpressionSP expr(target.GetUserExpressionForLanguage(
       code, llvm::StringRef(), language, UserExpression::eResultTypeAny,
       options, nullptr, error));
   if (error.Fail())
@@ -411,22 +408,19 @@ bool CommandObjectExpression::EvaluateExpression(llvm::StringRef expr,
   // command object DoExecute has finished when doing multi-line expression
   // that use an input reader...
   ExecutionContext exe_ctx(m_interpreter.GetExecutionContext());
-
-  Target *target = exe_ctx.GetTargetPtr();
-
-  if (!target)
-    target = &GetDummyTarget();
+  Target *exe_target = exe_ctx.GetTargetPtr();
+  Target &target = exe_target ? *exe_target : GetDummyTarget();
 
   lldb::ValueObjectSP result_valobj_sp;
   StackFrame *frame = exe_ctx.GetFramePtr();
 
-  const EvaluateExpressionOptions options = GetEvalOptions(*target);
-  ExpressionResults success = target->EvaluateExpression(
+  const EvaluateExpressionOptions options = GetEvalOptions(target);
+  ExpressionResults success = target.EvaluateExpression(
       expr, frame, result_valobj_sp, options, &m_fixed_expression);
 
   // We only tell you about the FixIt if we applied it.  The compiler errors
   // will suggest the FixIt if it parsed.
-  if (!m_fixed_expression.empty() && target->GetEnableNotifyAboutFixIts()) {
+  if (!m_fixed_expression.empty() && target.GetEnableNotifyAboutFixIts()) {
     if (success == eExpressionCompleted)
       error_stream.Printf("  Fix-it applied, fixed expression was: \n    %s\n",
                           m_fixed_expression.c_str());

lldb/source/Core/Debugger.cpp

@@ -1578,14 +1578,11 @@ void Debugger::JoinIOHandlerThread() {
   }
 }
 
-Target *Debugger::GetSelectedOrDummyTarget(bool prefer_dummy) {
-  Target *target = nullptr;
+Target &Debugger::GetSelectedOrDummyTarget(bool prefer_dummy) {
   if (!prefer_dummy) {
-    target = m_target_list.GetSelectedTarget().get();
-    if (target)
-      return target;
+    if (TargetSP target = m_target_list.GetSelectedTarget())
+      return *target;
   }
-
   return GetDummyTarget();
 }
 

lldb/source/Interpreter/CommandInterpreter.cpp

@@ -1523,16 +1523,12 @@ Status CommandInterpreter::PreprocessCommand(std::string &command) {
                          end_backtick - expr_content_start);
 
     ExecutionContext exe_ctx(GetExecutionContext());
-    Target *target = exe_ctx.GetTargetPtr();
 
     // Get a dummy target to allow for calculator mode while processing
     // backticks. This also helps break the infinite loop caused when target is
     // null.
-    if (!target)
-      target = m_debugger.GetDummyTarget();
-
-    if (!target)
-      continue;
+    Target *exe_target = exe_ctx.GetTargetPtr();
+    Target &target = exe_target ? *exe_target : m_debugger.GetDummyTarget();
 
     ValueObjectSP expr_result_valobj_sp;
 
@@ -1545,8 +1541,8 @@ Status CommandInterpreter::PreprocessCommand(std::string &command) {
     options.SetTimeout(llvm::None);
 
     ExpressionResults expr_result =
-        target->EvaluateExpression(expr_str.c_str(), exe_ctx.GetFramePtr(),
-                                   expr_result_valobj_sp, options);
+        target.EvaluateExpression(expr_str.c_str(), exe_ctx.GetFramePtr(),
+                                  expr_result_valobj_sp, options);
 
     if (expr_result == eExpressionCompleted) {
       Scalar scalar;

lldb/source/Interpreter/CommandObject.cpp

@@ -930,11 +930,11 @@ const char *CommandObject::GetArgumentDescriptionAsCString(
 }
 
 Target &CommandObject::GetDummyTarget() {
-  return *m_interpreter.GetDebugger().GetDummyTarget();
+  return m_interpreter.GetDebugger().GetDummyTarget();
 }
 
 Target &CommandObject::GetSelectedOrDummyTarget(bool prefer_dummy) {
-  return *m_interpreter.GetDebugger().GetSelectedOrDummyTarget(prefer_dummy);
+  return m_interpreter.GetDebugger().GetSelectedOrDummyTarget(prefer_dummy);
 }
 
 Target &CommandObject::GetSelectedTarget() {

lldb/source/Target/Target.cpp

@@ -128,13 +128,10 @@ Target::~Target() {
   DeleteCurrentProcess();
 }
 
-void Target::PrimeFromDummyTarget(Target *target) {
-  if (!target)
-    return;
+void Target::PrimeFromDummyTarget(Target &target) {
+  m_stop_hooks = target.m_stop_hooks;
 
-  m_stop_hooks = target->m_stop_hooks;
-
-  for (const auto &breakpoint_sp : target->m_breakpoint_list.Breakpoints()) {
+  for (const auto &breakpoint_sp : target.m_breakpoint_list.Breakpoints()) {
     if (breakpoint_sp->IsInternal())
       continue;
 
@@ -143,14 +140,14 @@ void Target::PrimeFromDummyTarget(Target *target) {
     AddBreakpoint(std::move(new_bp), false);
   }
 
-  for (auto bp_name_entry : target->m_breakpoint_names) {
+  for (auto bp_name_entry : target.m_breakpoint_names) {
 
     BreakpointName *new_bp_name = new BreakpointName(*bp_name_entry.second);
     AddBreakpointName(new_bp_name);
   }
 
   m_frame_recognizer_manager_up = std::make_unique<StackFrameRecognizerManager>(
-      *target->m_frame_recognizer_manager_up);
+      *target.m_frame_recognizer_manager_up);
 }
 
 void Target::Dump(Stream *s, lldb::DescriptionLevel description_level) {