[lldb] Delete dead StackFrameList::Merge

[teemperor]

Summary

That code is unused since it's check-in in 2010 (and I believe it would leak memory when called
as it releases the passed unique_ptr), so let's delete it.

[vsk]

+1

[shafik]

I think it is pretty safe to remove it after 10+ years is not being used.

lldb/include/lldb/Target/StackFrameList.h

size_t GetStatus(Stream &strm, uint32_t first_frame, uint32_t num_frames,
                    bool show_unique = false,
                    const char *frame_marker = nullptr);
 
 protected:
   friend class Thread;
 
   bool SetFrameAtIndex(uint32_t idx, lldb::StackFrameSP &frame_sp);
 
-  static void Merge(std::unique_ptr<StackFrameList> &curr_up,
-                    lldb::StackFrameListSP &prev_sp);
-
   void GetFramesUpTo(uint32_t end_idx);
 
   void GetOnlyConcreteFramesUpTo(uint32_t end_idx, Unwind &unwinder);
 
   void SynthesizeTailCallFrames(StackFrame &next_frame);
 
   bool GetAllFramesFetched() { return m_concrete_frames_fetched == UINT32_MAX; }
 

lldb/source/Target/StackFrameList.cpp

 // The thread has been run, reset the number stack frames to zero so we can
 // determine how many frames we have lazily.
 void StackFrameList::Clear() {
   std::lock_guard<std::recursive_mutex> guard(m_mutex);
   m_frames.clear();
   m_concrete_frames_fetched = 0;
 }
 
-void StackFrameList::Merge(std::unique_ptr<StackFrameList> &curr_up,
-                           lldb::StackFrameListSP &prev_sp) {
-  std::unique_lock<std::recursive_mutex> current_lock, previous_lock;
-  if (curr_up)
-    current_lock = std::unique_lock<std::recursive_mutex>(curr_up->m_mutex);
-  if (prev_sp)
-    previous_lock = std::unique_lock<std::recursive_mutex>(prev_sp->m_mutex);
-
-#if defined(DEBUG_STACK_FRAMES)
-  StreamFile s(stdout, false);
-  s.PutCString("\n\nStackFrameList::Merge():\nPrev:\n");
-  if (prev_sp)
-    prev_sp->Dump(&s);
-  else
-    s.PutCString("NULL");
-  s.PutCString("\nCurr:\n");
-  if (curr_up)
-    curr_up->Dump(&s);
-  else
-    s.PutCString("NULL");
-  s.EOL();
-#endif
-
-  if (!curr_up || curr_up->GetNumFrames(false) == 0) {
-#if defined(DEBUG_STACK_FRAMES)
-    s.PutCString("No current frames, leave previous frames alone...\n");
-#endif
-    curr_up.release();
-    return;
-  }
-
-  if (!prev_sp || prev_sp->GetNumFrames(false) == 0) {
-#if defined(DEBUG_STACK_FRAMES)
-    s.PutCString("No previous frames, so use current frames...\n");
-#endif
-    // We either don't have any previous frames, or since we have more than one
-    // current frames it means we have all the frames and can safely replace
-    // our previous frames.
-    prev_sp.reset(curr_up.release());
-    return;
-  }
-
-  const uint32_t num_curr_frames = curr_up->GetNumFrames(false);
-
-  if (num_curr_frames > 1) {
-#if defined(DEBUG_STACK_FRAMES)
-    s.PutCString(
-        "We have more than one current frame, so use current frames...\n");
-#endif
-    // We have more than one current frames it means we have all the frames and
-    // can safely replace our previous frames.
-    prev_sp.reset(curr_up.release());
-
-#if defined(DEBUG_STACK_FRAMES)
-    s.PutCString("\nMerged:\n");
-    prev_sp->Dump(&s);
-#endif
-    return;
-  }
-
-  StackFrameSP prev_frame_zero_sp(prev_sp->GetFrameAtIndex(0));
-  StackFrameSP curr_frame_zero_sp(curr_up->GetFrameAtIndex(0));
-  StackID curr_stack_id(curr_frame_zero_sp->GetStackID());
-  StackID prev_stack_id(prev_frame_zero_sp->GetStackID());
-
-#if defined(DEBUG_STACK_FRAMES)
-  const uint32_t num_prev_frames = prev_sp->GetNumFrames(false);
-  s.Printf("\n%u previous frames with one current frame\n", num_prev_frames);
-#endif
-
-  // We have only a single current frame
-  // Our previous stack frames only had a single frame as well...
-  if (curr_stack_id == prev_stack_id) {
-#if defined(DEBUG_STACK_FRAMES)
-    s.Printf("\nPrevious frame #0 is same as current frame #0, merge the "
-             "cached data\n");
-#endif
-
-    curr_frame_zero_sp->UpdateCurrentFrameFromPreviousFrame(
-        *prev_frame_zero_sp);
-    //        prev_frame_zero_sp->UpdatePreviousFrameFromCurrentFrame
-    //        (*curr_frame_zero_sp);
-    //        prev_sp->SetFrameAtIndex (0, prev_frame_zero_sp);
-  } else if (curr_stack_id < prev_stack_id) {
-#if defined(DEBUG_STACK_FRAMES)
-    s.Printf("\nCurrent frame #0 has a stack ID that is less than the previous "
-             "frame #0, insert current frame zero in front of previous\n");
-#endif
-    prev_sp->m_frames.insert(prev_sp->m_frames.begin(), curr_frame_zero_sp);
-  }
-
-  curr_up.release();
-
-#if defined(DEBUG_STACK_FRAMES)
-  s.PutCString("\nMerged:\n");
-  prev_sp->Dump(&s);
-#endif
-}
-
 lldb::StackFrameSP
 StackFrameList::GetStackFrameSPForStackFramePtr(StackFrame *stack_frame_ptr) {
   const_iterator pos;
   const_iterator begin = m_frames.begin();
   const_iterator end = m_frames.end();
   lldb::StackFrameSP ret_sp;
 
   for (pos = begin; pos != end; ++pos) {