Avoid infinite loops in stack backtraces and renamed:

    bool RegisterContextLLDB::GetPC (addr_t& pc);

to:
    bool RegisterContextLLDB::ReadPC (addr_t& pc);
    
To avoid confusion with the GetPC() function that is part of the 
lldb_private::RegisterContext:

    uint64_t RegisterContext::GetPC (uint64_t fail_value);
    
Bad things could happen if the two got intermixed and the wrong one got
called.

Fixed inifinite loop detection by watching for two frames where the
RegisterContextLLDB::CursorSP contains the same start_pc and cfa.

    

llvm-svn: 123673

3 files changed, 14 insertions, 5 deletions

diff --git a/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp b/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
index b76b093f88f..096ab1a9759 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
+++ b/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
@@ -1246,7 +1246,7 @@ RegisterContextLLDB::GetStartPC (addr_t& start_pc)
         return false;
     if (!m_start_pc.IsValid())
     {
-        return GetPC (start_pc); 
+        return ReadPC (start_pc); 
     }
     start_pc = m_start_pc.GetLoadAddress (&m_thread.GetProcess().GetTarget());
     return true;
@@ -1255,7 +1255,7 @@ RegisterContextLLDB::GetStartPC (addr_t& start_pc)
 // Retrieve the current pc value for THIS frame, as saved by the NEXT frame.
 
 bool
-RegisterContextLLDB::GetPC (addr_t& pc)
+RegisterContextLLDB::ReadPC (addr_t& pc)
 {
     if (!IsValid())
         return false;
diff --git a/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.h b/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.h
index 037836ba7bb..ba0e0522059 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.h
+++ b/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.h
@@ -72,7 +72,7 @@ public:
     GetStartPC (lldb::addr_t& start_pc);
 
     bool
-    GetPC (lldb::addr_t& start_pc);
+    ReadPC (lldb::addr_t& start_pc);
 
 private:
 
diff --git a/lldb/source/Plugins/Process/Utility/UnwindLLDB.cpp b/lldb/source/Plugins/Process/Utility/UnwindLLDB.cpp
index 30c867e26c6..533c21c6e24 100644
--- a/lldb/source/Plugins/Process/Utility/UnwindLLDB.cpp
+++ b/lldb/source/Plugins/Process/Utility/UnwindLLDB.cpp
@@ -76,7 +76,7 @@ UnwindLLDB::AddFirstFrame ()
     if (!first_register_ctx_ap->GetCFA (first_cursor_sp->cfa))
         return false;
 
-    if (!first_register_ctx_ap->GetPC (first_cursor_sp->start_pc))
+    if (!first_register_ctx_ap->ReadPC (first_cursor_sp->start_pc))
         return false;
 
     // Everything checks out, so release the auto pointer value and let the
@@ -132,7 +132,7 @@ UnwindLLDB::AddOneMoreFrame ()
         }
         return false;
     }
-    if (!register_ctx_ap->GetPC (cursor_sp->start_pc))
+    if (!register_ctx_ap->ReadPC (cursor_sp->start_pc))
     {
         if (log)
         {
@@ -141,6 +141,15 @@ UnwindLLDB::AddOneMoreFrame ()
         }
         return false;
     }
+    if (!m_frames.empty())
+    {
+        if ((m_frames.back()->start_pc == cursor_sp->start_pc) &&
+            (m_frames.back()->cfa      == cursor_sp->cfa))
+        {
+            // Infinite loop where the current cursor is the same as the previous one...
+            return false;
+        }
+    }
     RegisterContextSP register_ctx_sp(register_ctx_ap.release());
     cursor_sp->reg_ctx = register_ctx_sp;
     m_frames.push_back (cursor_sp);