When parsing the epilogue of a thumbv2 function, when we see the

frame pointer overwritten with the caller's fp value, return to 
expressing the CFA in terms of the stack pointer.
<rdar://problem/11855862>

llvm-svn: 160150

1 files changed, 14 insertions, 0 deletions

diff --git a/lldb/source/Plugins/UnwindAssembly/InstEmulation/UnwindAssemblyInstEmulation.cpp b/lldb/source/Plugins/UnwindAssembly/InstEmulation/UnwindAssemblyInstEmulation.cpp
index 6d2b0a54b6a..58416dd5ea3 100644
--- a/lldb/source/Plugins/UnwindAssembly/InstEmulation/UnwindAssemblyInstEmulation.cpp
+++ b/lldb/source/Plugins/UnwindAssembly/InstEmulation/UnwindAssemblyInstEmulation.cpp
@@ -490,6 +490,20 @@ UnwindAssemblyInstEmulation::WriteRegister (EmulateInstruction *instruction,
                 {
                     m_curr_row.SetRegisterLocationToSame (reg_num, must_replace);
                 }
+                // if we just restored the caller's reg value in the reg we were using for the frame pointer,
+                // change the CFA to be in terms of the stack pointer again.
+                if (m_fp_is_cfa && reg_num == m_cfa_reg_info.kinds[m_unwind_plan_ptr->GetRegisterKind()])
+                {
+                    m_fp_is_cfa = false;
+                    m_inst_emulator_ap->GetRegisterInfo (m_unwind_plan_ptr->GetRegisterKind(), 
+                                                         m_unwind_plan_ptr->GetInitialCFARegister(), 
+                                                         m_cfa_reg_info);
+                    m_curr_row.SetCFARegister(m_cfa_reg_info.kinds[m_unwind_plan_ptr->GetRegisterKind()]);
+                    if (log && log->GetVerbose())
+                    {
+                        log->Printf("UnwindAssemblyInstEmulation::WriteRegister - CFA is expressed in terms of %s again", m_cfa_reg_info.name);
+                    }
+                }
             }
             break;