Improve instruction emulation based stack unwinding on ARM

* Add and fix the emulation of several instruction.
* Disable frame pointer usage on Android.
* Specify return address register for the unwind plan instead of explict
  tracking the value of RA.
* Replace prologue detection heuristics (unreliable in several cases)
  with a logic to follow the branch instructions and restore the CFI
  value based on them. The target address for a branch should have the
  same CFI as the source address (if they are in the same function).
* Handle symbols in ELF files where the symbol size is not specified
  with calcualting their size based on the next symbol (already done
  in MachO files).
* Fix architecture in FuncUnwinders with filling up the inforamtion
  missing from the object file with the architecture of the target.
* Add code to read register wehn the value is set to "IsSame" as it
  meanse the value of a register in the parent frame is the same as the
  value in the current frame.

Differential revision: http://reviews.llvm.org/D10447

llvm-svn: 240533

1 files changed, 8 insertions, 11 deletions

diff --git a/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp b/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
index 22058ce0833..7f14985b8f2 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
+++ b/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
@@ -692,7 +692,7 @@ RegisterContextLLDB::GetFastUnwindPlanForFrame ()
     if (m_frame_type == eTrapHandlerFrame || m_frame_type == eDebuggerFrame)
         return unwind_plan_sp;
 
-    unwind_plan_sp = func_unwinders_sp->GetUnwindPlanFastUnwind (m_thread);
+    unwind_plan_sp = func_unwinders_sp->GetUnwindPlanFastUnwind (*m_thread.CalculateTarget(), m_thread);
     if (unwind_plan_sp)
     {
         if (unwind_plan_sp->PlanValidAtAddress (m_current_pc))
@@ -1403,16 +1403,13 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
 
     if (unwindplan_regloc.IsSame())
     {
-        if (IsFrameZero ())
-        {
-            UnwindLogMsg ("could not supply caller's %s (%d) location, IsSame", 
-                          regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
-            return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
-        }
-        else
-        {
-            return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
-        }
+        regloc.type = UnwindLLDB::RegisterLocation::eRegisterInRegister;
+        regloc.location.register_number = regnum.GetAsKind (eRegisterKindLLDB);
+        m_registers[regnum.GetAsKind (eRegisterKindLLDB)] = regloc;
+        UnwindLogMsg ("supplying caller's register %s (%d), saved in register %s (%d)", 
+                      regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB), 
+                      regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
+        return UnwindLLDB::RegisterSearchResult::eRegisterFound;
     }
 
     if (unwindplan_regloc.IsCFAPlusOffset())