Put more smarts into the RegisterContext base class. Now the base class has

a method:

    void RegisterContext::InvalidateIfNeeded (bool force);

Each time this function is called, when "force" is false, it will only call
the pure virtual "virtual void RegisterContext::InvalideAllRegisters()" if
the register context's stop ID doesn't match that of the process. When the
stop ID doesn't match, or "force" is true, the base class will clear its
cached registers and the RegisterContext will update its stop ID to match
that of the process. This helps make it easier to correctly flush the register
context (possibly from multiple locations depending on when and where new
registers are availabe) without inadvertently clearing the register cache 
when it doesn't need to be.

Modified the ProcessGDBRemote plug-in to be much more efficient when it comes
to:
- caching the expedited registers in the stop reply packets (we were ignoring
  these before and it was causing us to read at least three registers every
  time we stopped that were already supplied in the stop reply packet).
- When a thread has no stop reason, don't keep asking for the thread stopped
  info. Prior to this fix we would continually send a qThreadStopInfo packet
  over and over when any thread stop info was requested. We now note the stop
  ID that the stop info was requested for and avoid multiple requests.

Cleaned up some of the expression code to not look for ClangExpressionVariable
objects up by name since they are now shared pointers and we can just look for
the exact pointer match and avoid possible errors.

Fixed an bug in the ValueObject code that would cause children to not be 
displayed.

llvm-svn: 123127

17 files changed, 132 insertions, 64 deletions

diff --git a/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_arm.cpp b/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_arm.cpp
index 29c06bb625b..55e5534a5d8 100644
--- a/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_arm.cpp
+++ b/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_arm.cpp
@@ -394,7 +394,7 @@ g_exc_regnums[] =
 static size_t k_num_register_infos = (sizeof(g_register_infos)/sizeof(RegisterInfo));
 
 void
-RegisterContextMach_arm::Invalidate ()
+RegisterContextMach_arm::InvalidateAllRegisters ()
 {
     InvalidateAllRegisterStates();
 }
diff --git a/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_arm.h b/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_arm.h
index 158e701f02d..3f9654c72c8 100644
--- a/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_arm.h
+++ b/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_arm.h
@@ -60,7 +60,7 @@ public:
     ~RegisterContextMach_arm();
 
     virtual void
-    Invalidate ();
+    InvalidateAllRegisters ();
 
     virtual size_t
     GetRegisterCount ();
diff --git a/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_i386.cpp b/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_i386.cpp
index fe23e7ae7b3..077a492bbf4 100644
--- a/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_i386.cpp
+++ b/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_i386.cpp
@@ -275,7 +275,7 @@ static RegisterInfo g_register_infos[] =
 static size_t k_num_register_infos = (sizeof(g_register_infos)/sizeof(RegisterInfo));
 
 void
-RegisterContextMach_i386::Invalidate ()
+RegisterContextMach_i386::InvalidateAllRegisters ()
 {
     InvalidateAllRegisterStates();
 }
diff --git a/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_i386.h b/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_i386.h
index 20c5e3d9a2b..7a3c5dad08b 100644
--- a/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_i386.h
+++ b/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_i386.h
@@ -28,7 +28,7 @@ public:
     ~RegisterContextMach_i386();
 
     virtual void
-    Invalidate ();
+    InvalidateAllRegisters ();
 
     virtual size_t
     GetRegisterCount ();
diff --git a/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_x86_64.cpp b/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_x86_64.cpp
index 21e05267755..8b1ed79d3c7 100644
--- a/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_x86_64.cpp
+++ b/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_x86_64.cpp
@@ -311,7 +311,7 @@ static size_t k_num_register_infos = (sizeof(g_register_infos)/sizeof(RegisterIn
 
 
 void
-RegisterContextMach_x86_64::Invalidate ()
+RegisterContextMach_x86_64::InvalidateAllRegisters ()
 {
     InvalidateAllRegisterStates();
 }
diff --git a/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_x86_64.h b/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_x86_64.h
index 0fc8ca5150b..316575c9aa7 100644
--- a/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_x86_64.h
+++ b/lldb/source/Plugins/Process/MacOSX-User/source/RegisterContextMach_x86_64.h
@@ -27,7 +27,7 @@ public:
     ~RegisterContextMach_x86_64();
 
     virtual void
-    Invalidate ();
+    InvalidateAllRegisters ();
 
     virtual size_t
     GetRegisterCount ();
diff --git a/lldb/source/Plugins/Process/MacOSX-User/source/ThreadMacOSX.cpp b/lldb/source/Plugins/Process/MacOSX-User/source/ThreadMacOSX.cpp
index 2f01dc6e8b8..900153f747e 100644
--- a/lldb/source/Plugins/Process/MacOSX-User/source/ThreadMacOSX.cpp
+++ b/lldb/source/Plugins/Process/MacOSX-User/source/ThreadMacOSX.cpp
@@ -198,7 +198,7 @@ void
 ThreadMacOSX::RefreshStateAfterStop()
 {
     // Invalidate all registers in our register context
-    GetRegisterContext()->Invalidate();
+    GetRegisterContext()->InvalidateIfNeeded (false);
 
     m_context->RefreshStateAfterStop();
 
@@ -650,7 +650,7 @@ ThreadMacOSX::RestoreSaveFrameZero (const RegisterCheckpoint &checkpoint)
 
         // Clear out all stack frames as our world just changed.
         ClearStackFrames();
-        frame_sp->GetRegisterContext()->Invalidate();
+        frame_sp->GetRegisterContext()->InvalidateIfNeeded(true);
 
         return ret;
     }
diff --git a/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp b/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
index 8aadc04f1ff..b76b093f88f 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
+++ b/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
@@ -633,7 +633,7 @@ RegisterContextLLDB::GetFullUnwindPlanForFrame ()
 
 
 void
-RegisterContextLLDB::Invalidate ()
+RegisterContextLLDB::InvalidateAllRegisters ()
 {
     m_frame_type = eNotAValidFrame;
 }
diff --git a/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.h b/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.h
index 57e89a3f991..037836ba7bb 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.h
+++ b/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.h
@@ -33,7 +33,7 @@ public:
     ~RegisterContextLLDB () { }
 
     virtual void
-    Invalidate ();
+    InvalidateAllRegisters ();
 
     virtual size_t
     GetRegisterCount ();
diff --git a/lldb/source/Plugins/Process/Utility/RegisterContextMacOSXFrameBackchain.cpp b/lldb/source/Plugins/Process/Utility/RegisterContextMacOSXFrameBackchain.cpp
index ec915cc0e4e..68a207c9ec9 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterContextMacOSXFrameBackchain.cpp
+++ b/lldb/source/Plugins/Process/Utility/RegisterContextMacOSXFrameBackchain.cpp
@@ -46,7 +46,7 @@ RegisterContextMacOSXFrameBackchain::~RegisterContextMacOSXFrameBackchain()
 }
 
 void
-RegisterContextMacOSXFrameBackchain::Invalidate ()
+RegisterContextMacOSXFrameBackchain::InvalidateAllRegisters ()
 {
     m_cursor_is_valid = false;
 }
diff --git a/lldb/source/Plugins/Process/Utility/RegisterContextMacOSXFrameBackchain.h b/lldb/source/Plugins/Process/Utility/RegisterContextMacOSXFrameBackchain.h
index 9da4e92db21..7997a23a194 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterContextMacOSXFrameBackchain.h
+++ b/lldb/source/Plugins/Process/Utility/RegisterContextMacOSXFrameBackchain.h
@@ -36,7 +36,7 @@ public:
     // Subclasses must override these functions
     //------------------------------------------------------------------
     virtual void
-    Invalidate ();
+    InvalidateAllRegisters ();
 
     virtual size_t
     GetRegisterCount ();
diff --git a/lldb/source/Plugins/Process/Utility/UnwindLLDB.cpp b/lldb/source/Plugins/Process/Utility/UnwindLLDB.cpp
index 75f92bbef28..30c867e26c6 100644
--- a/lldb/source/Plugins/Process/Utility/UnwindLLDB.cpp
+++ b/lldb/source/Plugins/Process/Utility/UnwindLLDB.cpp
@@ -35,6 +35,7 @@ UnwindLLDB::GetFrameCount()
     {
 //#define DEBUG_FRAME_SPEED 1
 #if DEBUG_FRAME_SPEED
+#define FRAME_COUNT 10000
         TimeValue time_value (TimeValue::Now());
 #endif
         if (!AddFirstFrame ())
@@ -42,11 +43,15 @@ UnwindLLDB::GetFrameCount()
         while (AddOneMoreFrame ())
         {
 #if DEBUG_FRAME_SPEED
-            if ((m_frames.size() % 10000) == 0)
+            if ((m_frames.size() % FRAME_COUNT) == 0)
             {
                 TimeValue now(TimeValue::Now());
                 uint64_t delta_t = now - time_value;
-                printf ("10000 frames in %llu.%09llu ms\n", delta_t / NSEC_PER_SEC, delta_t % NSEC_PER_SEC);
+                printf ("%u frames in %llu.%09llu ms (%g frames/sec)\n", 
+                        FRAME_COUNT,
+                        delta_t / NSEC_PER_SEC, 
+                        delta_t % NSEC_PER_SEC,
+                        (float)FRAME_COUNT / ((float)delta_t / (float)NSEC_PER_SEC));
                 time_value = now;
             }
 #endif
diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteRegisterContext.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteRegisterContext.cpp
index 978daa7e9ca..eaf91eb98b1 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteRegisterContext.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteRegisterContext.cpp
@@ -39,7 +39,6 @@ GDBRemoteRegisterContext::GDBRemoteRegisterContext
     RegisterContext (thread, concrete_frame_idx),
     m_reg_info (reg_info),
     m_reg_valid (),
-    m_reg_valid_stop_id (),
     m_reg_data (),
     m_read_all_at_once (read_all_at_once)
 {
@@ -74,7 +73,7 @@ GDBRemoteRegisterContext::GetGDBThread()
 }
 
 void
-GDBRemoteRegisterContext::Invalidate ()
+GDBRemoteRegisterContext::InvalidateAllRegisters ()
 {
     SetAllRegisterValid (false);
 }
@@ -179,25 +178,41 @@ GDBRemoteRegisterContext::ReadRegisterValue (uint32_t reg, Scalar &value)
     return false;
 }
 
+void
+GDBRemoteRegisterContext::PrivateSetRegisterValue (uint32_t reg, StringExtractor &response)
+{
+    const RegisterInfo *reg_info = GetRegisterInfoAtIndex (reg);
+    assert (reg_info);
+
+    // Invalidate if needed
+    InvalidateIfNeeded(false);
+
+    const uint32_t reg_byte_size = reg_info->byte_size;
+    const size_t bytes_copied = response.GetHexBytes (const_cast<uint8_t*>(m_reg_data.PeekData(reg_info->byte_offset, reg_byte_size)), reg_byte_size, '\xcc');
+    bool success = bytes_copied == reg_byte_size;
+    if (success)
+    {
+        m_reg_valid[reg] = true;
+    }
+    else if (bytes_copied > 0)
+    {
+        // Only set register is valid to false if we copied some bytes, else 
+        // leave it as it was.
+        m_reg_valid[reg] = false;
+    }
+}
+
 
 bool
 GDBRemoteRegisterContext::ReadRegisterBytes (uint32_t reg, DataExtractor &data)
 {
     GDBRemoteCommunication &gdb_comm = GetGDBProcess().GetGDBRemote();
-// FIXME: This check isn't right because IsRunning checks the Public state, but this
-// is work you need to do - for instance in ShouldStop & friends - before the public 
-// state has been changed.
-//    if (gdb_comm.IsRunning())
-//        return false;
 
-    if (m_reg_valid_stop_id != m_thread.GetProcess().GetStopID())
-    {
-        Invalidate();
-        m_reg_valid_stop_id = m_thread.GetProcess().GetStopID();
-    }
+    InvalidateIfNeeded(false);
+
     const RegisterInfo *reg_info = GetRegisterInfoAtIndex (reg);
     assert (reg_info);
-    if (m_reg_valid[reg] == false)
+    if (!m_reg_valid[reg])
     {
         Mutex::Locker locker;
         if (gdb_comm.GetSequenceMutex (locker))
@@ -225,28 +240,27 @@ GDBRemoteRegisterContext::ReadRegisterBytes (uint32_t reg, DataExtractor &data)
                     packet_len = ::snprintf (packet, sizeof(packet), "p%x", reg);
                     assert (packet_len < (sizeof(packet) - 1));
                     if (gdb_comm.SendPacketAndWaitForResponse(packet, response, 1, false))
-                        if (response.GetHexBytes (const_cast<uint8_t*>(m_reg_data.PeekData(reg_info->byte_offset, reg_info->byte_size)), reg_info->byte_size, '\xcc') == reg_info->byte_size)
-                            m_reg_valid[reg] = true;
+                        PrivateSetRegisterValue (reg, response);
                 }
             }
         }
+
+        // Make sure we got a valid register value after reading it
+        if (!m_reg_valid[reg])
+            return false;
     }
 
-    bool reg_is_valid = m_reg_valid[reg];
-    if (reg_is_valid)
+    if (&data != &m_reg_data)
     {
-        if (&data != &m_reg_data)
-        {
-            // If we aren't extracting into our own buffer (which
-            // only happens when this function is called from
-            // ReadRegisterValue(uint32_t, Scalar&)) then
-            // we transfer bytes from our buffer into the data
-            // buffer that was passed in
-            data.SetByteOrder (m_reg_data.GetByteOrder());
-            data.SetData (m_reg_data, reg_info->byte_offset, reg_info->byte_size);
-        }
+        // If we aren't extracting into our own buffer (which
+        // only happens when this function is called from
+        // ReadRegisterValue(uint32_t, Scalar&)) then
+        // we transfer bytes from our buffer into the data
+        // buffer that was passed in
+        data.SetByteOrder (m_reg_data.GetByteOrder());
+        data.SetData (m_reg_data, reg_info->byte_offset, reg_info->byte_size);
     }
-    return reg_is_valid;
+    return true;
 }
 
 
@@ -323,8 +337,8 @@ GDBRemoteRegisterContext::WriteRegisterBytes (uint32_t reg, DataExtractor &data,
                                               eByteOrderHost);
                     
                     // Invalidate all register values
-                    Invalidate ();
-                    
+                    InvalidateIfNeeded (true);
+
                     if (gdb_comm.SendPacketAndWaitForResponse(packet.GetString().c_str(),
                                                               packet.GetString().size(),
                                                               response,
diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteRegisterContext.h b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteRegisterContext.h
index e20da52527b..72c640ff7a8 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteRegisterContext.h
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteRegisterContext.h
@@ -25,6 +25,7 @@
 
 class ThreadGDBRemote;
 class ProcessGDBRemote;
+class StringExtractor;
 
 class GDBRemoteDynamicRegisterInfo
 {
@@ -189,7 +190,7 @@ public:
     // Subclasses must override these functions
     //------------------------------------------------------------------
     virtual void
-    Invalidate ();
+    InvalidateAllRegisters ();
 
     virtual size_t
     GetRegisterCount ();
@@ -225,8 +226,12 @@ public:
     ConvertRegisterKindToRegisterNumber (uint32_t kind, uint32_t num);
 
 protected:
+    friend class ThreadGDBRemote;
 
     void
+    PrivateSetRegisterValue (uint32_t reg, StringExtractor &response);
+    
+    void
     SetAllRegisterValid (bool b);
 
     ProcessGDBRemote &
@@ -237,7 +242,6 @@ protected:
 
     GDBRemoteDynamicRegisterInfo &m_reg_info;
     std::vector<bool> m_reg_valid;
-    uint32_t m_reg_valid_stop_id;
     lldb_private::DataExtractor m_reg_data;
     bool m_read_all_at_once;
 
diff --git a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
index 3775d5b9ff6..cee3e6fd8b9 100644
--- a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
@@ -975,9 +975,7 @@ ProcessGDBRemote::UpdateThreadListIfNeeded ()
                     if (tid != LLDB_INVALID_THREAD_ID)
                     {
                         ThreadSP thread_sp (GetThreadList().FindThreadByID (tid, false));
-                        if (thread_sp)
-                            thread_sp->GetRegisterContext()->Invalidate();
-                        else
+                        if (!thread_sp)
                             thread_sp.reset (new ThreadGDBRemote (*this, tid));
                         curr_thread_list.AddThread(thread_sp);
                     }
@@ -1014,6 +1012,8 @@ ProcessGDBRemote::SetThreadStopInfo (StringExtractor& stop_packet)
             uint32_t tid = LLDB_INVALID_THREAD_ID;
             addr_t thread_dispatch_qaddr = LLDB_INVALID_ADDRESS;
             uint32_t exc_data_count = 0;
+            ThreadSP thread_sp;
+
             while (stop_packet.GetNameColonValue(name, value))
             {
                 if (name.compare("metype") == 0)
@@ -1035,6 +1035,7 @@ ProcessGDBRemote::SetThreadStopInfo (StringExtractor& stop_packet)
                 {
                     // thread in big endian hex
                     tid = Args::StringToUInt32 (value.c_str(), 0, 16);
+                    thread_sp = m_thread_list.FindThreadByID(tid, false);
                 }
                 else if (name.compare("hexname") == 0)
                 {
@@ -1053,8 +1054,25 @@ ProcessGDBRemote::SetThreadStopInfo (StringExtractor& stop_packet)
                 {
                     thread_dispatch_qaddr = Args::StringToUInt64 (value.c_str(), 0, 16);
                 }
+                else if (name.size() == 2 && ::isxdigit(name[0]) && ::isxdigit(name[1]))
+                {
+                    // We have a register number that contains an expedited
+                    // register value. Lets supply this register to our thread
+                    // so it won't have to go and read it.
+                    if (thread_sp)
+                    {
+                        uint32_t reg = Args::StringToUInt32 (name.c_str(), UINT32_MAX, 16);
+
+                        if (reg != UINT32_MAX)
+                        {
+                            StringExtractor reg_value_extractor;
+                            // Swap "value" over into "reg_value_extractor"
+                            reg_value_extractor.GetStringRef().swap(value);
+                            static_cast<ThreadGDBRemote *> (thread_sp.get())->PrivateSetRegisterValue (reg, reg_value_extractor);
+                        }
+                    }
+                }
             }
-            ThreadSP thread_sp (m_thread_list.FindThreadByID(tid, false));
 
             if (thread_sp)
             {
diff --git a/lldb/source/Plugins/Process/gdb-remote/ThreadGDBRemote.cpp b/lldb/source/Plugins/Process/gdb-remote/ThreadGDBRemote.cpp
index 091feb9e649..b8108bfd383 100644
--- a/lldb/source/Plugins/Process/gdb-remote/ThreadGDBRemote.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/ThreadGDBRemote.cpp
@@ -37,7 +37,8 @@ ThreadGDBRemote::ThreadGDBRemote (ProcessGDBRemote &process, lldb::tid_t tid) :
     Thread(process, tid),
     m_thread_name (),
     m_dispatch_queue_name (),
-    m_thread_dispatch_qaddr (LLDB_INVALID_ADDRESS)
+    m_thread_dispatch_qaddr (LLDB_INVALID_ADDRESS),
+    m_thread_stop_reason_stop_id (0)
 {
 //    ProcessGDBRemoteLog::LogIf(GDBR_LOG_THREAD | GDBR_LOG_VERBOSE, "ThreadGDBRemote::ThreadGDBRemote ( pid = %i, tid = 0x%4.4x, )", m_process.GetID(), GetID());
     ProcessGDBRemoteLog::LogIf(GDBR_LOG_THREAD, "%p: ThreadGDBRemote::ThreadGDBRemote (pid = %i, tid = 0x%4.4x)", this, m_process.GetID(), GetID());
@@ -116,14 +117,18 @@ ThreadGDBRemote::WillResume (StateType resume_state)
 void
 ThreadGDBRemote::RefreshStateAfterStop()
 {
-    // Invalidate all registers in our register context
-    GetRegisterContext()->Invalidate();
+    // Invalidate all registers in our register context. We don't set "force" to
+    // true because the stop reply packet might have had some register values
+    // that were expedited and these will already be copied into the register
+    // context by the time this function gets called. The GDBRemoteRegisterContext
+    // class has been made smart enough to detect when it needs to invalidate
+    // which registers are valid by putting hooks in the register read and 
+    // register supply functions where they check the process stop ID and do
+    // the right thing.
+    const bool force = false;
+    GetRegisterContext()->InvalidateIfNeeded (force);
 }
 
-// Whether to use the new native unwinder (UnwindLLDB) or the libunwind-remote based unwinder for
-// stack walks on i386/x86_64
-#define USE_NATIVE_UNWINDER
-
 Unwind *
 ThreadGDBRemote::GetUnwinder ()
 {
@@ -132,11 +137,7 @@ ThreadGDBRemote::GetUnwinder ()
         const ArchSpec target_arch (GetProcess().GetTarget().GetArchitecture ());
         if (target_arch == ArchSpec("x86_64") ||  target_arch == ArchSpec("i386"))
         {
-#if defined (USE_NATIVE_UNWINDER)
             m_unwinder_ap.reset (new UnwindLLDB (*this));
-#else
-            m_unwinder_ap.reset (new UnwindLibUnwind (*this, GetGDBProcess().GetLibUnwindAddressSpace()));
-#endif
         }
         else
         {
@@ -198,6 +199,14 @@ ThreadGDBRemote::CreateRegisterContextForFrame (StackFrame *frame)
     return reg_ctx_sp;
 }
 
+void
+ThreadGDBRemote::PrivateSetRegisterValue (uint32_t reg, StringExtractor &response)
+{
+    GDBRemoteRegisterContext *gdb_reg_ctx = static_cast<GDBRemoteRegisterContext *>(GetRegisterContext ().get());
+    assert (gdb_reg_ctx);
+    gdb_reg_ctx->PrivateSetRegisterValue (reg, response);
+}
+
 bool
 ThreadGDBRemote::SaveFrameZeroState (RegisterCheckpoint &checkpoint)
 {
@@ -217,7 +226,7 @@ ThreadGDBRemote::RestoreSaveFrameZero (const RegisterCheckpoint &checkpoint)
     if (frame_sp)
     {
         bool ret = frame_sp->GetRegisterContext()->WriteAllRegisterValues (checkpoint.GetData());
-        frame_sp->GetRegisterContext()->Invalidate();
+        frame_sp->GetRegisterContext()->InvalidateIfNeeded(true);
         ClearStackFrames();
         return ret;
     }
@@ -227,8 +236,19 @@ ThreadGDBRemote::RestoreSaveFrameZero (const RegisterCheckpoint &checkpoint)
 lldb::StopInfoSP
 ThreadGDBRemote::GetPrivateStopReason ()
 {
-    if (m_actual_stop_info_sp.get() == NULL || m_actual_stop_info_sp->IsValid() == false)
+    const uint32_t process_stop_id = GetProcess().GetStopID();
+    if (m_thread_stop_reason_stop_id != process_stop_id ||
+        (m_actual_stop_info_sp && !m_actual_stop_info_sp->IsValid()))
     {
+        // If GetGDBProcess().SetThreadStopInfo() doesn't find a stop reason
+        // for this thread, then m_actual_stop_info_sp will not ever contain
+        // a valid stop reason and the "m_actual_stop_info_sp->IsValid() == false"
+        // check will never be able to tell us if we have the correct stop info
+        // for this thread and we will continually send qThreadStopInfo packets
+        // down to the remote GDB server, so we need to keep our own notion
+        // of the stop ID that m_actual_stop_info_sp is valid for (even if it
+        // contains nothing). We use m_thread_stop_reason_stop_id for this below.
+        m_thread_stop_reason_stop_id = process_stop_id;
         m_actual_stop_info_sp.reset();
 
         char packet[256];
@@ -236,7 +256,6 @@ ThreadGDBRemote::GetPrivateStopReason ()
         StringExtractorGDBRemote stop_packet;
         if (GetGDBProcess().GetGDBRemote().SendPacketAndWaitForResponse(packet, stop_packet, 1, false))
         {
-            std::string copy(stop_packet.GetStringRef());
             GetGDBProcess().SetThreadStopInfo (stop_packet);
         }
     }
diff --git a/lldb/source/Plugins/Process/gdb-remote/ThreadGDBRemote.h b/lldb/source/Plugins/Process/gdb-remote/ThreadGDBRemote.h
index 37aae88ed34..3bf54afa9be 100644
--- a/lldb/source/Plugins/Process/gdb-remote/ThreadGDBRemote.h
+++ b/lldb/source/Plugins/Process/gdb-remote/ThreadGDBRemote.h
@@ -108,12 +108,20 @@ public:
     }
 
 protected:
+    
+    friend class ProcessGDBRemote;
+
+    void
+    PrivateSetRegisterValue (uint32_t reg, 
+                             StringExtractor &response);
+                             
     //------------------------------------------------------------------
     // Member variables.
     //------------------------------------------------------------------
     std::string m_thread_name;
     std::string m_dispatch_queue_name;
     lldb::addr_t m_thread_dispatch_qaddr;
+    uint32_t m_thread_stop_reason_stop_id;
     //------------------------------------------------------------------
     // Member variables.
     //------------------------------------------------------------------