[Lldb-commits] [PATCH] D103271: [lldb/Target] Select most relevant frame only in case of signal

[Levon Ter-Grigoryan via Phabricator via lldb-commits]

PatriosTheGreat updated this revision to Diff 352966.
PatriosTheGreat added a comment.

Thanks for the review feedback.
Looks like moving frame recognizer call to StackFrameList::GetFramesUpTo also fixes infinity recursion issue.

Regarding the zeroth frame issue: I'm actually using the lldb-server compiled with followed cmake command:
cmake -G Ninja -DLLVM_ENABLE_PROJECTS='lldb;clang;libcxx'  ../llvm

I see a performance improvement even on a local run, however it's not as huge:
In the sample I provided previously with this patch the execution time will be around 4 seconds instead of 6 seconds without it during the local run.

I see at the profiler that asking 0th frame triggers UnwindLLDB::DoGetFrameInfoAtIndex -> UnwindLLDB::AddFirstFrame -> UnwindLLDB::UpdateUnwindPlanForFirstFrameIfInvalid -> UnwindLLDB::AddOneMoreFrame -> UnwindLLDB::GetOneMoreFrame -> RegisterContextUnwind::RegisterContextUnwind -> RegisterContextUnwind::InitializeNonZerothFrame

- which is costly.

If I understand correctly the LLDB won't do any of this for background threads by default.

Could it be that accelerated stop-reply packets you said previously is turned off by default in lldb-server and I need to set a special setting to turn them on?


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D103271/new/

https://reviews.llvm.org/D103271

Files:
  lldb/include/lldb/Target/Thread.h
  lldb/source/Target/StackFrameList.cpp
  lldb/source/Target/Thread.cpp


Index: lldb/source/Target/Thread.cpp
===================================================================
--- lldb/source/Target/Thread.cpp
+++ lldb/source/Target/Thread.cpp
@@ -578,15 +578,9 @@
   return raw_stop_description;
 }
 
-void Thread::SelectMostRelevantFrame() {
+void Thread::SelectMostRelevantFrame(lldb::StackFrameSP first_frame) {
   Log *log = lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_THREAD);
-
-  auto frames_list_sp = GetStackFrameList();
-
-  // Only the top frame should be recognized.
-  auto frame_sp = frames_list_sp->GetFrameAtIndex(0);
-
-  auto recognized_frame_sp = frame_sp->GetRecognizedFrame();
+  auto recognized_frame_sp = first_frame->GetRecognizedFrame();
 
   if (!recognized_frame_sp) {
     LLDB_LOG(log, "Frame #0 not recognized");
@@ -606,8 +600,6 @@
 void Thread::WillStop() {
   ThreadPlan *current_plan = GetCurrentPlan();
 
-  SelectMostRelevantFrame();
-
   // FIXME: I may decide to disallow threads with no plans.  In which
   // case this should go to an assert.
 
Index: lldb/source/Target/StackFrameList.cpp
===================================================================
--- lldb/source/Target/StackFrameList.cpp
+++ lldb/source/Target/StackFrameList.cpp
@@ -547,6 +547,9 @@
         curr_frame_address = next_frame_address;
       }
     }
+
+    if (idx == 0)
+      m_thread.SelectMostRelevantFrame(unwind_frame_sp);
   } while (m_frames.size() - 1 < end_idx);
 
   // Don't try to merge till you've calculated all the frames in this stack.
Index: lldb/include/lldb/Target/Thread.h
===================================================================
--- lldb/include/lldb/Target/Thread.h
+++ lldb/include/lldb/Target/Thread.h
@@ -218,7 +218,7 @@
 
   virtual void RefreshStateAfterStop() = 0;
 
-  void SelectMostRelevantFrame();
+  void SelectMostRelevantFrame(lldb::StackFrameSP first_frame);
 
   std::string GetStopDescription();
 


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