Improve instruction emulation based stack unwinding

On ARM there is no difference petween a pop and a load instruction so
a register can be loaded multiple times during the function. Add check
to threat the load as a restore only if it do the restore from the
same location where the register was saved.

Differential revision: http://reviews.llvm.org/D11947

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@245546 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 11 insertions, 2 deletions

diff --git a/source/Plugins/UnwindAssembly/InstEmulation/UnwindAssemblyInstEmulation.cpp b/source/Plugins/UnwindAssembly/InstEmulation/UnwindAssemblyInstEmulation.cpp
index 5c016d04e..a7e98be9e 100644
--- a/source/Plugins/UnwindAssembly/InstEmulation/UnwindAssemblyInstEmulation.cpp
+++ b/source/Plugins/UnwindAssembly/InstEmulation/UnwindAssemblyInstEmulation.cpp
@@ -580,8 +580,17 @@ UnwindAssemblyInstEmulation::WriteRegister (EmulateInstruction *instruction,
                     const uint32_t generic_regnum = reg_info->kinds[eRegisterKindGeneric];
                     if (reg_num != LLDB_INVALID_REGNUM && generic_regnum != LLDB_REGNUM_GENERIC_SP)
                     {
-                        m_curr_row->SetRegisterLocationToSame (reg_num, /*must_replace*/ false);
-                        m_curr_row_modified = true;
+                        if (context.info_type == EmulateInstruction::eInfoTypeAddress)
+                        {
+                            if (m_pushed_regs.find (reg_num) != m_pushed_regs.end () &&
+                                context.info.address == m_pushed_regs[reg_num])
+                            {
+                                m_curr_row->SetRegisterLocationToSame (reg_num, /*must_replace*/ false);
+                                m_curr_row_modified = true;
+                            }
+                        }
+                        else
+                            assert (!"unhandled case, add code to handle this!");
                     }
                 }
             }