Thread hardening part 3. Now lldb_private::Thread objects have std::weak_ptr

objects for the backlink to the lldb_private::Process. The issues we were
running into before was someone was holding onto a shared pointer to a 
lldb_private::Thread for too long, and the lldb_private::Process parent object
would get destroyed and the lldb_private::Thread had a "Process &m_process"
member which would just treat whatever memory that used to be a Process as a
valid Process. This was mostly happening for lldb_private::StackFrame objects
that had a member like "Thread &m_thread". So this completes the internal
strong/weak changes.

Documented the ExecutionContext and ExecutionContextRef classes so that our
LLDB developers can understand when and where to use ExecutionContext and 
ExecutionContextRef objects.

llvm-svn: 151009

5 files changed, 104 insertions, 74 deletions

diff --git a/lldb/source/Plugins/Process/MacOSX-Kernel/ProcessKDP.cpp b/lldb/source/Plugins/Process/MacOSX-Kernel/ProcessKDP.cpp
index ab872f8e7d7..3b45691d2e0 100644
--- a/lldb/source/Plugins/Process/MacOSX-Kernel/ProcessKDP.cpp
+++ b/lldb/source/Plugins/Process/MacOSX-Kernel/ProcessKDP.cpp
@@ -312,7 +312,7 @@ ProcessKDP::UpdateThreadList (ThreadList &old_thread_list, ThreadList &new_threa
         lldb::tid_t tid = cpu_mask_bit;
         ThreadSP thread_sp (old_thread_list.FindThreadByID (tid, false));
         if (!thread_sp)
-            thread_sp.reset(new ThreadKDP (*this, tid));
+            thread_sp.reset(new ThreadKDP (shared_from_this(), tid));
         new_thread_list.AddThread(thread_sp);
     }
     return new_thread_list.GetSize(false);
diff --git a/lldb/source/Plugins/Process/MacOSX-Kernel/RegisterContextKDP_arm.cpp b/lldb/source/Plugins/Process/MacOSX-Kernel/RegisterContextKDP_arm.cpp
index fdd22b2f3b3..296fbbac7e9 100644
--- a/lldb/source/Plugins/Process/MacOSX-Kernel/RegisterContextKDP_arm.cpp
+++ b/lldb/source/Plugins/Process/MacOSX-Kernel/RegisterContextKDP_arm.cpp
@@ -33,11 +33,15 @@ RegisterContextKDP_arm::~RegisterContextKDP_arm()
 int
 RegisterContextKDP_arm::DoReadGPR (lldb::tid_t tid, int flavor, GPR &gpr)
 {
-    Error error;
-    if (m_kdp_thread.GetKDPProcess().GetCommunication().SendRequestReadRegisters (tid, GPRRegSet, &gpr, sizeof(gpr), error))
+    ProcessSP process_sp (CalculateProcess());
+    if (process_sp)
     {
-        if (error.Success())
-            return 0;
+        Error error;
+        if (static_cast<ProcessKDP *>(process_sp.get())->GetCommunication().SendRequestReadRegisters (tid, GPRRegSet, &gpr, sizeof(gpr), error))
+        {
+            if (error.Success())
+                return 0;
+        }
     }
     return -1;
 }
@@ -45,11 +49,15 @@ RegisterContextKDP_arm::DoReadGPR (lldb::tid_t tid, int flavor, GPR &gpr)
 int
 RegisterContextKDP_arm::DoReadFPU (lldb::tid_t tid, int flavor, FPU &fpu)
 {
-    Error error;
-    if (m_kdp_thread.GetKDPProcess().GetCommunication().SendRequestReadRegisters (tid, FPURegSet, &fpu, sizeof(fpu), error))
+    ProcessSP process_sp (CalculateProcess());
+    if (process_sp)
     {
-        if (error.Success())
-            return 0;
+        Error error;
+        if (static_cast<ProcessKDP *>(process_sp.get())->GetCommunication().SendRequestReadRegisters (tid, FPURegSet, &fpu, sizeof(fpu), error))
+        {
+            if (error.Success())
+                return 0;
+        }
     }
     return -1;
 }
@@ -57,11 +65,15 @@ RegisterContextKDP_arm::DoReadFPU (lldb::tid_t tid, int flavor, FPU &fpu)
 int
 RegisterContextKDP_arm::DoReadEXC (lldb::tid_t tid, int flavor, EXC &exc)
 {
-    Error error;
-    if (m_kdp_thread.GetKDPProcess().GetCommunication().SendRequestReadRegisters (tid, EXCRegSet, &exc, sizeof(exc), error))
+    ProcessSP process_sp (CalculateProcess());
+    if (process_sp)
     {
-        if (error.Success())
-            return 0;
+        Error error;
+        if (static_cast<ProcessKDP *>(process_sp.get())->GetCommunication().SendRequestReadRegisters (tid, EXCRegSet, &exc, sizeof(exc), error))
+        {
+            if (error.Success())
+                return 0;
+        }
     }
     return -1;
 }
@@ -69,11 +81,15 @@ RegisterContextKDP_arm::DoReadEXC (lldb::tid_t tid, int flavor, EXC &exc)
 int
 RegisterContextKDP_arm::DoReadDBG (lldb::tid_t tid, int flavor, DBG &dbg)
 {
-    Error error;
-    if (m_kdp_thread.GetKDPProcess().GetCommunication().SendRequestReadRegisters (tid, DBGRegSet, &dbg, sizeof(dbg), error))
+    ProcessSP process_sp (CalculateProcess());
+    if (process_sp)
     {
-        if (error.Success())
-            return 0;
+        Error error;
+        if (static_cast<ProcessKDP *>(process_sp.get())->GetCommunication().SendRequestReadRegisters (tid, DBGRegSet, &dbg, sizeof(dbg), error))
+        {
+            if (error.Success())
+                return 0;
+        }
     }
     return -1;
 }
diff --git a/lldb/source/Plugins/Process/MacOSX-Kernel/RegisterContextKDP_i386.cpp b/lldb/source/Plugins/Process/MacOSX-Kernel/RegisterContextKDP_i386.cpp
index 503ce75181c..504ea07ba4f 100644
--- a/lldb/source/Plugins/Process/MacOSX-Kernel/RegisterContextKDP_i386.cpp
+++ b/lldb/source/Plugins/Process/MacOSX-Kernel/RegisterContextKDP_i386.cpp
@@ -33,11 +33,15 @@ RegisterContextKDP_i386::~RegisterContextKDP_i386()
 int
 RegisterContextKDP_i386::DoReadGPR (lldb::tid_t tid, int flavor, GPR &gpr)
 {
-    Error error;
-    if (m_kdp_thread.GetKDPProcess().GetCommunication().SendRequestReadRegisters (tid, GPRRegSet, &gpr, sizeof(gpr), error))
+    ProcessSP process_sp (CalculateProcess());
+    if (process_sp)
     {
-        if (error.Success())
-            return 0;
+        Error error;
+        if (static_cast<ProcessKDP *>(process_sp.get())->GetCommunication().SendRequestReadRegisters (tid, GPRRegSet, &gpr, sizeof(gpr), error))
+        {
+            if (error.Success())
+                return 0;
+        }
     }
     return -1;
 }
@@ -45,11 +49,15 @@ RegisterContextKDP_i386::DoReadGPR (lldb::tid_t tid, int flavor, GPR &gpr)
 int
 RegisterContextKDP_i386::DoReadFPU (lldb::tid_t tid, int flavor, FPU &fpu)
 {
-    Error error;
-    if (m_kdp_thread.GetKDPProcess().GetCommunication().SendRequestReadRegisters (tid, FPURegSet, &fpu, sizeof(fpu), error))
+    ProcessSP process_sp (CalculateProcess());
+    if (process_sp)
     {
-        if (error.Success())
-            return 0;
+        Error error;
+        if (static_cast<ProcessKDP *>(process_sp.get())->GetCommunication().SendRequestReadRegisters (tid, FPURegSet, &fpu, sizeof(fpu), error))
+        {
+            if (error.Success())
+                return 0;
+        }
     }
     return -1;
 }
@@ -57,11 +65,15 @@ RegisterContextKDP_i386::DoReadFPU (lldb::tid_t tid, int flavor, FPU &fpu)
 int
 RegisterContextKDP_i386::DoReadEXC (lldb::tid_t tid, int flavor, EXC &exc)
 {
-    Error error;
-    if (m_kdp_thread.GetKDPProcess().GetCommunication().SendRequestReadRegisters (tid, EXCRegSet, &exc, sizeof(exc), error))
+    ProcessSP process_sp (CalculateProcess());
+    if (process_sp)
     {
-        if (error.Success())
-            return 0;
+        Error error;
+        if (static_cast<ProcessKDP *>(process_sp.get())->GetCommunication().SendRequestReadRegisters (tid, EXCRegSet, &exc, sizeof(exc), error))
+        {
+            if (error.Success())
+                return 0;
+        }
     }
     return -1;
 }
@@ -69,19 +81,19 @@ RegisterContextKDP_i386::DoReadEXC (lldb::tid_t tid, int flavor, EXC &exc)
 int
 RegisterContextKDP_i386::DoWriteGPR (lldb::tid_t tid, int flavor, const GPR &gpr)
 {
-    return ::thread_set_state(tid, flavor, (thread_state_t)&gpr, GPRWordCount);
+    return -1;
 }
 
 int
 RegisterContextKDP_i386::DoWriteFPU (lldb::tid_t tid, int flavor, const FPU &fpu)
 {
-    return ::thread_set_state(tid, flavor, (thread_state_t)&fpu, FPUWordCount);
+    return -1;
 }
 
 int
 RegisterContextKDP_i386::DoWriteEXC (lldb::tid_t tid, int flavor, const EXC &exc)
 {
-    return ::thread_set_state(tid, flavor, (thread_state_t)&exc, EXCWordCount);
+    return -1;
 }
 
 
diff --git a/lldb/source/Plugins/Process/MacOSX-Kernel/ThreadKDP.cpp b/lldb/source/Plugins/Process/MacOSX-Kernel/ThreadKDP.cpp
index 6fb947087e5..9f68d104942 100644
--- a/lldb/source/Plugins/Process/MacOSX-Kernel/ThreadKDP.cpp
+++ b/lldb/source/Plugins/Process/MacOSX-Kernel/ThreadKDP.cpp
@@ -36,18 +36,18 @@ using namespace lldb_private;
 // Thread Registers
 //----------------------------------------------------------------------
 
-ThreadKDP::ThreadKDP (ProcessKDP &process, lldb::tid_t tid) :
-    Thread(process, tid),
+ThreadKDP::ThreadKDP (const lldb::ProcessSP &process_sp, lldb::tid_t tid) :
+    Thread(process_sp, tid),
     m_thread_name (),
     m_dispatch_queue_name (),
     m_thread_dispatch_qaddr (LLDB_INVALID_ADDRESS)
 {
-    ProcessKDPLog::LogIf(KDP_LOG_THREAD, "%p: ThreadKDP::ThreadKDP (pid = %i, tid = 0x%4.4x)", this, m_process.GetID(), GetID());
+    ProcessKDPLog::LogIf(KDP_LOG_THREAD, "%p: ThreadKDP::ThreadKDP (tid = 0x%4.4x)", this, GetID());
 }
 
 ThreadKDP::~ThreadKDP ()
 {
-    ProcessKDPLog::LogIf(KDP_LOG_THREAD, "%p: ThreadKDP::~ThreadKDP (pid = %i, tid = 0x%4.4x)", this, m_process.GetID(), GetID());
+    ProcessKDPLog::LogIf(KDP_LOG_THREAD, "%p: ThreadKDP::~ThreadKDP (tid = 0x%4.4x)", this, GetID());
     DestroyThread();
 }
 
@@ -157,20 +157,24 @@ ThreadKDP::CreateRegisterContextForFrame (StackFrame *frame)
 
     if (concrete_frame_idx == 0)
     {
-        switch (GetKDPProcess().GetCommunication().GetCPUType())
+        ProcessSP process_sp (CalculateProcess());
+        if (process_sp)
         {
-            case llvm::MachO::CPUTypeARM:
-                reg_ctx_sp.reset (new RegisterContextKDP_arm (*this, concrete_frame_idx));
-                break;
-            case llvm::MachO::CPUTypeI386:
-                reg_ctx_sp.reset (new RegisterContextKDP_i386 (*this, concrete_frame_idx));
-                break;
-            case llvm::MachO::CPUTypeX86_64:
-                reg_ctx_sp.reset (new RegisterContextKDP_x86_64 (*this, concrete_frame_idx));
-                break;
-            default:
-                assert (!"Add CPU type support in KDP");
-                break;
+            switch (static_cast<ProcessKDP *>(process_sp.get())->GetCommunication().GetCPUType())
+            {
+                case llvm::MachO::CPUTypeARM:
+                    reg_ctx_sp.reset (new RegisterContextKDP_arm (*this, concrete_frame_idx));
+                    break;
+                case llvm::MachO::CPUTypeI386:
+                    reg_ctx_sp.reset (new RegisterContextKDP_i386 (*this, concrete_frame_idx));
+                    break;
+                case llvm::MachO::CPUTypeX86_64:
+                    reg_ctx_sp.reset (new RegisterContextKDP_x86_64 (*this, concrete_frame_idx));
+                    break;
+                default:
+                    assert (!"Add CPU type support in KDP");
+                    break;
+            }
         }
     }
     else if (m_unwinder_ap.get())
@@ -181,26 +185,30 @@ ThreadKDP::CreateRegisterContextForFrame (StackFrame *frame)
 lldb::StopInfoSP
 ThreadKDP::GetPrivateStopReason ()
 {
-    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()))
+    ProcessSP process_sp (GetProcess());
+    if (process_sp)
     {
-        // TODO: can we query the initial state of the thread here?
-        // For now I am just going to pretend that a SIGSTOP happened.
-
-        SetStopInfo(StopInfo::CreateStopReasonWithSignal (*this, SIGSTOP));
-
-        // If GetKDPProcess().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 KDP 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();
+        const uint32_t process_stop_id = process_sp->GetStopID();
+        if (m_thread_stop_reason_stop_id != process_stop_id ||
+            (m_actual_stop_info_sp && !m_actual_stop_info_sp->IsValid()))
+        {
+            // TODO: can we query the initial state of the thread here?
+            // For now I am just going to pretend that a SIGSTOP happened.
+
+            SetStopInfo(StopInfo::CreateStopReasonWithSignal (*this, SIGSTOP));
+
+            // If GetKDPProcess().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 KDP 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();
 
+        }
     }
     return m_actual_stop_info_sp;
 }
diff --git a/lldb/source/Plugins/Process/MacOSX-Kernel/ThreadKDP.h b/lldb/source/Plugins/Process/MacOSX-Kernel/ThreadKDP.h
index a37fa91ee2b..1bf688de20a 100644
--- a/lldb/source/Plugins/Process/MacOSX-Kernel/ThreadKDP.h
+++ b/lldb/source/Plugins/Process/MacOSX-Kernel/ThreadKDP.h
@@ -20,7 +20,7 @@ class ProcessKDP;
 class ThreadKDP : public lldb_private::Thread
 {
 public:
-    ThreadKDP (ProcessKDP &process, 
+    ThreadKDP (const lldb::ProcessSP &process_sp, 
                lldb::tid_t tid);
 
     virtual
@@ -47,12 +47,6 @@ public:
     virtual void
     ClearStackFrames ();
 
-    ProcessKDP &
-    GetKDPProcess ()
-    {
-        return (ProcessKDP &)m_process;
-    }
-
     void
     Dump (lldb_private::Log *log, uint32_t index);