[lldb] Consider "hidden" frames in ThreadPlanShouldStopHere

Patch [1] introduced the notion of "hidden" frames, which are recognized
by language plugins and can be hidden in backtraces. They also affect
stepping out: when stepping out of a frame, if its parent frame is
"hidden", then the debugger steps out to the parent's parent.

However, this is problematic when stepping out is done as part of a
larger plan. For example, when stepping through, the debugger is often
in some frame A, then pushes some frame B, and decides to step out of B
and back to A. If A is a hidden frame, LLDB currenly steps out past it,
which is not what the step through plan intended.

To address this issue, we create a new flag for the ShouldStopHere base
class to allow for stepping past hidden frames. This flag is now the
default for stepping out.  Furthermore,
`ThreadPlanShouldStopHere::DefaultStepFromHereCallback` now passes its
own set of flags to the constructor of ThreadPlanStepOut.

One potentially controversial choice: all StepOut plans created through
`ThreadPlanShouldStopHere::DefaultStepFromHereCallback` will pass on
their set of flags to ThreadPlanStepOut, which will disable the behavior
of stepping past hidden frames.

[1]: llvm#104523

Author: felipepiovezan

lldb/include/lldb/Target/Thread.h

@@ -942,7 +942,8 @@ class Thread : public std::enable_shared_from_this<Thread>,
   virtual lldb::ThreadPlanSP QueueThreadPlanForStepOutNoShouldStop(
       bool abort_other_plans, SymbolContext *addr_context, bool first_insn,
       bool stop_other_threads, Vote report_stop_vote, Vote report_run_vote,
-      uint32_t frame_idx, Status &status, bool continue_to_next_branch = false);
+      uint32_t frame_idx, Status &status, bool continue_to_next_branch = false,
+      const Flags *flags = nullptr);
 
   /// Gets the plan used to step through the code that steps from a function
   /// call site at the current PC into the actual function call.

lldb/include/lldb/Target/ThreadPlanShouldStopHere.h

@@ -60,7 +60,8 @@ class ThreadPlanShouldStopHere {
     eAvoidInlines = (1 << 0),
     eStepInAvoidNoDebug = (1 << 1),
     eStepOutAvoidNoDebug = (1 << 2),
-    eStepOutPastThunks = (1 << 3)
+    eStepOutPastThunks = (1 << 3),
+    eStepOutPastHiddenFunctions = (1 << 4),
   };
 
   // Constructors and Destructors

lldb/include/lldb/Target/ThreadPlanStepOut.h

@@ -22,7 +22,8 @@ class ThreadPlanStepOut : public ThreadPlan, public ThreadPlanShouldStopHere {
                     Vote report_run_vote, uint32_t frame_idx,
                     LazyBool step_out_avoids_code_without_debug_info,
                     bool continue_to_next_branch = false,
-                    bool gather_return_value = true);
+                    bool gather_return_value = true,
+                    const Flags *flags = nullptr);
 
   ~ThreadPlanStepOut() override;
 

lldb/source/Target/Thread.cpp

@@ -1356,13 +1356,14 @@ ThreadPlanSP Thread::QueueThreadPlanForStepOut(
 ThreadPlanSP Thread::QueueThreadPlanForStepOutNoShouldStop(
     bool abort_other_plans, SymbolContext *addr_context, bool first_insn,
     bool stop_other_threads, Vote report_stop_vote, Vote report_run_vote,
-    uint32_t frame_idx, Status &status, bool continue_to_next_branch) {
+    uint32_t frame_idx, Status &status, bool continue_to_next_branch,
+    const Flags *flags) {
   const bool calculate_return_value =
       false; // No need to calculate the return value here.
   ThreadPlanSP thread_plan_sp(new ThreadPlanStepOut(
       *this, addr_context, first_insn, stop_other_threads, report_stop_vote,
       report_run_vote, frame_idx, eLazyBoolNo, continue_to_next_branch,
-      calculate_return_value));
+      calculate_return_value, flags));
 
   ThreadPlanStepOut *new_plan =
       static_cast<ThreadPlanStepOut *>(thread_plan_sp.get());

lldb/source/Target/ThreadPlanShouldStopHere.cpp

@@ -177,7 +177,7 @@ ThreadPlanSP ThreadPlanShouldStopHere::DefaultStepFromHereCallback(
     return_plan_sp =
         current_plan->GetThread().QueueThreadPlanForStepOutNoShouldStop(
             false, nullptr, true, stop_others, eVoteNo, eVoteNoOpinion,
-            frame_index, status, true);
+            frame_index, status, true, &flags);
   return return_plan_sp;
 }
 

lldb/source/Target/ThreadPlanStepOut.cpp

@@ -29,14 +29,15 @@
 using namespace lldb;
 using namespace lldb_private;
 
-uint32_t ThreadPlanStepOut::s_default_flag_values = 0;
+uint32_t ThreadPlanStepOut::s_default_flag_values =
+    ThreadPlanShouldStopHere::eStepOutPastHiddenFunctions;
 
 // ThreadPlanStepOut: Step out of the current frame
 ThreadPlanStepOut::ThreadPlanStepOut(
     Thread &thread, SymbolContext *context, bool first_insn, bool stop_others,
     Vote report_stop_vote, Vote report_run_vote, uint32_t frame_idx,
     LazyBool step_out_avoids_code_without_debug_info,
-    bool continue_to_next_branch, bool gather_return_value)
+    bool continue_to_next_branch, bool gather_return_value, const Flags *flags)
     : ThreadPlan(ThreadPlan::eKindStepOut, "Step out", thread, report_stop_vote,
                  report_run_vote),
       ThreadPlanShouldStopHere(this), m_step_from_insn(LLDB_INVALID_ADDRESS),
@@ -45,7 +46,10 @@ ThreadPlanStepOut::ThreadPlanStepOut(
       m_immediate_step_from_function(nullptr),
       m_calculate_return_value(gather_return_value) {
   Log *log = GetLog(LLDBLog::Step);
-  SetFlagsToDefault();
+  if (flags)
+    m_flags = *flags;
+  else
+    SetFlagsToDefault();
   SetupAvoidNoDebug(step_out_avoids_code_without_debug_info);
 
   m_step_from_insn = thread.GetRegisterContext()->GetPC(0);
@@ -58,7 +62,9 @@ ThreadPlanStepOut::ThreadPlanStepOut(
     return; // we can't do anything here.  ValidatePlan() will return false.
 
   // While stepping out, behave as-if artificial frames are not present.
-  while (return_frame_sp->IsArtificial() || return_frame_sp->IsHidden()) {
+  while (return_frame_sp->IsArtificial() ||
+         (m_flags.Test(eStepOutPastHiddenFunctions) &&
+          return_frame_sp->IsHidden())) {
     m_stepped_past_frames.push_back(return_frame_sp);
 
     ++return_frame_index;