<rdar://problem/13516463>

Don't crash when there is no register context for a thread with kernel debugging. The kernel debugging uses the OperatingSystemPlugin that may behave badly when trying to get thread state, so be prepared to have invalid register contexts in threads.

llvm-svn: 178574

1 files changed, 66 insertions, 45 deletions

diff --git a/lldb/source/Target/Thread.cpp b/lldb/source/Target/Thread.cpp
index e1264a12ead..378d0266d5a 100644
--- a/lldb/source/Target/Thread.cpp
+++ b/lldb/source/Target/Thread.cpp
@@ -479,33 +479,37 @@ Thread::SetupForResume ()
         // telling the current plan it will resume, since we might change what the current
         // plan is.
 
-//        StopReason stop_reason = lldb::eStopReasonInvalid;
-//        StopInfoSP stop_info_sp = GetStopInfo();
-//        if (stop_info_sp.get())
-//            stop_reason = stop_info_sp->GetStopReason();
-//        if (stop_reason == lldb::eStopReasonBreakpoint)
-        BreakpointSiteSP bp_site_sp = GetProcess()->GetBreakpointSiteList().FindByAddress(GetRegisterContext()->GetPC());
-        if (bp_site_sp)
+//      StopReason stop_reason = lldb::eStopReasonInvalid;
+//      StopInfoSP stop_info_sp = GetStopInfo();
+//      if (stop_info_sp.get())
+//          stop_reason = stop_info_sp->GetStopReason();
+//      if (stop_reason == lldb::eStopReasonBreakpoint)
+        lldb::RegisterContextSP reg_ctx_sp (GetRegisterContext());
+        if (reg_ctx_sp)
         {
-            // Note, don't assume there's a ThreadPlanStepOverBreakpoint, the target may not require anything
-            // special to step over a breakpoint.
-                
-            ThreadPlan *cur_plan = GetCurrentPlan();
-
-            if (cur_plan->GetKind() != ThreadPlan::eKindStepOverBreakpoint)
+            BreakpointSiteSP bp_site_sp = GetProcess()->GetBreakpointSiteList().FindByAddress(reg_ctx_sp->GetPC());
+            if (bp_site_sp)
             {
-                ThreadPlanStepOverBreakpoint *step_bp_plan = new ThreadPlanStepOverBreakpoint (*this);
-                if (step_bp_plan)
-                {
-                    ThreadPlanSP step_bp_plan_sp;
-                    step_bp_plan->SetPrivate (true);
+                // Note, don't assume there's a ThreadPlanStepOverBreakpoint, the target may not require anything
+                // special to step over a breakpoint.
+                    
+                ThreadPlan *cur_plan = GetCurrentPlan();
 
-                    if (GetCurrentPlan()->RunState() != eStateStepping)
+                if (cur_plan->GetKind() != ThreadPlan::eKindStepOverBreakpoint)
+                {
+                    ThreadPlanStepOverBreakpoint *step_bp_plan = new ThreadPlanStepOverBreakpoint (*this);
+                    if (step_bp_plan)
                     {
-                        step_bp_plan->SetAutoContinue(true);
+                        ThreadPlanSP step_bp_plan_sp;
+                        step_bp_plan->SetPrivate (true);
+
+                        if (GetCurrentPlan()->RunState() != eStateStepping)
+                        {
+                            step_bp_plan->SetAutoContinue(true);
+                        }
+                        step_bp_plan_sp.reset (step_bp_plan);
+                        QueueThreadPlan (step_bp_plan_sp, false);
                     }
-                    step_bp_plan_sp.reset (step_bp_plan);
-                    QueueThreadPlan (step_bp_plan_sp, false);
                 }
             }
         }
@@ -595,7 +599,7 @@ Thread::ShouldStop (Event* event_ptr)
             log->Printf ("Thread::%s for tid = 0x%4.4" PRIx64 ", pc = 0x%16.16" PRIx64 ", should_stop = 0 (ignore since no stop reason)",
                          __FUNCTION__, 
                          GetID (), 
-                         GetRegisterContext()->GetPC());
+                         GetRegisterContext() ? GetRegisterContext()->GetPC() : LLDB_INVALID_ADDRESS);
         return false;
     }
     
@@ -604,7 +608,7 @@ Thread::ShouldStop (Event* event_ptr)
         log->Printf ("Thread::%s for tid = 0x%4.4" PRIx64 ", pc = 0x%16.16" PRIx64,
                      __FUNCTION__, 
                      GetID (), 
-                     GetRegisterContext()->GetPC());
+                     GetRegisterContext() ? GetRegisterContext()->GetPC() : LLDB_INVALID_ADDRESS);
         log->Printf ("^^^^^^^^ Thread::ShouldStop Begin ^^^^^^^^");
         StreamString s;
         s.IndentMore();
@@ -1587,17 +1591,25 @@ Thread::ReturnFromFrame (lldb::StackFrameSP frame_sp, lldb::ValueObjectSP return
     StackFrameSP youngest_frame_sp = thread->GetStackFrameAtIndex(0);
     if (youngest_frame_sp)
     {
-        bool copy_success = youngest_frame_sp->GetRegisterContext()->CopyFromRegisterContext(older_frame_sp->GetRegisterContext());
-        if (copy_success)
+        lldb::RegisterContextSP reg_ctx_sp (youngest_frame_sp->GetRegisterContext());
+        if (reg_ctx_sp)
         {
-            thread->DiscardThreadPlans(true);
-            thread->ClearStackFrames();
-            if (broadcast && EventTypeHasListeners(eBroadcastBitStackChanged))
-                BroadcastEvent(eBroadcastBitStackChanged, new ThreadEventData (this->shared_from_this()));
+            bool copy_success = reg_ctx_sp->CopyFromRegisterContext(older_frame_sp->GetRegisterContext());
+            if (copy_success)
+            {
+                thread->DiscardThreadPlans(true);
+                thread->ClearStackFrames();
+                if (broadcast && EventTypeHasListeners(eBroadcastBitStackChanged))
+                    BroadcastEvent(eBroadcastBitStackChanged, new ThreadEventData (this->shared_from_this()));
+            }
+            else
+            {
+                return_error.SetErrorString("Could not reset register values.");
+            }
         }
         else
         {
-            return_error.SetErrorString("Could not reset register values.");
+            return_error.SetErrorString("Frame has no register context.");
         }
     }
     else
@@ -1760,7 +1772,9 @@ Thread::SaveFrameZeroState (RegisterCheckpoint &checkpoint)
     if (frame_sp)
     {
         checkpoint.SetStackID(frame_sp->GetStackID());
-        return frame_sp->GetRegisterContext()->ReadAllRegisterValues (checkpoint.GetData());
+        lldb::RegisterContextSP reg_ctx_sp (frame_sp->GetRegisterContext());
+        if (reg_ctx_sp)
+            return reg_ctx_sp->ReadAllRegisterValues (checkpoint.GetData());
     }
     return false;
 }
@@ -1777,15 +1791,18 @@ Thread::ResetFrameZeroRegisters (lldb::DataBufferSP register_data_sp)
     lldb::StackFrameSP frame_sp(GetStackFrameAtIndex (0));
     if (frame_sp)
     {
-        bool ret = frame_sp->GetRegisterContext()->WriteAllRegisterValues (register_data_sp);
-
-        // Clear out all stack frames as our world just changed.
-        ClearStackFrames();
-        frame_sp->GetRegisterContext()->InvalidateIfNeeded(true);
-        if (m_unwinder_ap.get())
-            m_unwinder_ap->Clear();
-
-        return ret;
+        lldb::RegisterContextSP reg_ctx_sp (frame_sp->GetRegisterContext());
+        if (reg_ctx_sp)
+        {
+            bool ret = reg_ctx_sp->WriteAllRegisterValues (register_data_sp);
+
+            // Clear out all stack frames as our world just changed.
+            ClearStackFrames();
+            reg_ctx_sp->InvalidateIfNeeded(true);
+            if (m_unwinder_ap.get())
+                m_unwinder_ap->Clear();
+            return ret;
+        }
     }
     return false;
 }
@@ -1833,10 +1850,14 @@ Thread::IsStillAtLastBreakpointHit ()
         StopReason stop_reason = m_actual_stop_info_sp->GetStopReason();
         if (stop_reason == lldb::eStopReasonBreakpoint) {
             uint64_t value = m_actual_stop_info_sp->GetValue();
-            lldb::addr_t pc = GetRegisterContext()->GetPC();
-            BreakpointSiteSP bp_site_sp = GetProcess()->GetBreakpointSiteList().FindByAddress(pc);
-            if (bp_site_sp && value == bp_site_sp->GetID())
-                return true;
+            lldb::RegisterContextSP reg_ctx_sp (GetRegisterContext());
+            if (reg_ctx_sp)
+            {
+                lldb::addr_t pc = reg_ctx_sp->GetPC();
+                BreakpointSiteSP bp_site_sp = GetProcess()->GetBreakpointSiteList().FindByAddress(pc);
+                if (bp_site_sp && value == bp_site_sp->GetID())
+                    return true;
+            }
         }
     }
     return false;