After we've completed a full backtrace, we'll have one frame which

is "invalid" -- it is past the end of the stack trace.  Add a new
method IsCompletedStackWalk() so we can tell if an invalid stack
frame is from a complete backtrace or if it might be worth re-trying
the last unwind with a different method.

This fixes the unwinder problems Ryan Brown was having with go
programs.  The unwinder can (under the right circumstances) still
destructively replace unwind plans permanently - I'll work on
that in a different patch.  

<rdar://problem/18683658> 

llvm-svn: 221229

1 files changed, 7 insertions, 0 deletions

diff --git a/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.h b/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.h
index ff0b77488eb..d272073de55 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.h
+++ b/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.h
@@ -73,6 +73,9 @@ public:
     IsValid () const;
 
     bool
+    IsCompletedStackWalk () const;
+
+    bool
     IsTrapHandlerFrame () const;
 
     bool
@@ -240,6 +243,10 @@ private:
 
     lldb_private::UnwindLLDB& m_parent_unwind;    // The UnwindLLDB that is creating this RegisterContextLLDB
 
+    bool m_completed_stack_walk;                  // indicates that we completed a full stack walk 
+                                                  // (this frame is likely eNotAValidFrame aka !IsValid())
+                                                  // and we should not continue trying to unwind
+
     //------------------------------------------------------------------
     // For RegisterContextLLDB only
     //------------------------------------------------------------------