Move StopInfoOverride callback to the new architecture plugin

This creates a new Architecture plugin and moves the stop info override
callback to this place. The motivation for this is to remove complex
dependencies from the ArchSpec class because it is used in a lot of
places that (should) know nothing about Process instances and StopInfo
objects.

I also add a test for the functionality covered by the override
callback.

Differential Revision: https://reviews.llvm.org/D31172

llvm-svn: 316609

11 files changed, 285 insertions, 157 deletions

diff --git a/lldb/source/API/SystemInitializerFull.cpp b/lldb/source/API/SystemInitializerFull.cpp
index c505f61e42a..977ebe62353 100644
--- a/lldb/source/API/SystemInitializerFull.cpp
+++ b/lldb/source/API/SystemInitializerFull.cpp
@@ -42,6 +42,7 @@
 #include "Plugins/ABI/SysV-ppc64/ABISysV_ppc64.h"
 #include "Plugins/ABI/SysV-s390x/ABISysV_s390x.h"
 #include "Plugins/ABI/SysV-x86_64/ABISysV_x86_64.h"
+#include "Plugins/Architecture/Arm/ArchitectureArm.h"
 #include "Plugins/Disassembler/llvm/DisassemblerLLVMC.h"
 #include "Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOS.h"
 #include "Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOSXDYLD.h"
@@ -50,9 +51,9 @@
 #include "Plugins/DynamicLoader/Windows-DYLD/DynamicLoaderWindowsDYLD.h"
 #include "Plugins/Instruction/ARM64/EmulateInstructionARM64.h"
 #include "Plugins/InstrumentationRuntime/ASan/ASanRuntime.h"
+#include "Plugins/InstrumentationRuntime/MainThreadChecker/MainThreadCheckerRuntime.h"
 #include "Plugins/InstrumentationRuntime/TSan/TSanRuntime.h"
 #include "Plugins/InstrumentationRuntime/UBSan/UBSanRuntime.h"
-#include "Plugins/InstrumentationRuntime/MainThreadChecker/MainThreadCheckerRuntime.h"
 #include "Plugins/JITLoader/GDB/JITLoaderGDB.h"
 #include "Plugins/Language/CPlusPlus/CPlusPlusLanguage.h"
 #include "Plugins/Language/Go/GoLanguage.h"
@@ -304,6 +305,9 @@ void SystemInitializerFull::Initialize() {
   ABISysV_mips::Initialize();
   ABISysV_mips64::Initialize();
   ABISysV_s390x::Initialize();
+
+  ArchitectureArm::Initialize();
+
   DisassemblerLLVMC::Initialize();
 
   JITLoaderGDB::Initialize();
diff --git a/lldb/source/Core/ArchSpec.cpp b/lldb/source/Core/ArchSpec.cpp
index 43ca15a8b89..07c31f391ab 100644
--- a/lldb/source/Core/ArchSpec.cpp
+++ b/lldb/source/Core/ArchSpec.cpp
@@ -11,17 +11,12 @@
 
 #include "lldb/Host/HostInfo.h"
 #include "lldb/Target/Platform.h"
-#include "lldb/Target/RegisterContext.h"
-#include "lldb/Target/Thread.h"
 #include "lldb/Utility/NameMatches.h"
 #include "lldb/Utility/Stream.h" // for Stream
 #include "lldb/Utility/StringList.h"
 #include "lldb/lldb-defines.h" // for LLDB_INVALID_C...
 #include "lldb/lldb-forward.h" // for RegisterContextSP
 
-#include "Plugins/Process/Utility/ARMDefines.h"
-#include "Plugins/Process/Utility/InstructionUtils.h"
-
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/Twine.h" // for Twine
 #include "llvm/BinaryFormat/COFF.h"
@@ -1506,102 +1501,6 @@ bool lldb_private::operator<(const ArchSpec &lhs, const ArchSpec &rhs) {
   return lhs_core < rhs_core;
 }
 
-static void StopInfoOverrideCallbackTypeARM(lldb_private::Thread &thread) {
-  // We need to check if we are stopped in Thumb mode in a IT instruction
-  // and detect if the condition doesn't pass. If this is the case it means
-  // we won't actually execute this instruction. If this happens we need to
-  // clear the stop reason to no thread plans think we are stopped for a
-  // reason and the plans should keep going.
-  //
-  // We do this because when single stepping many ARM processes, debuggers
-  // often use the BVR/BCR registers that says "stop when the PC is not
-  // equal to its current value". This method of stepping means we can end
-  // up stopping on instructions inside an if/then block that wouldn't get
-  // executed. By fixing this we can stop the debugger from seeming like
-  // you stepped through both the "if" _and_ the "else" clause when source
-  // level stepping because the debugger stops regardless due to the BVR/BCR
-  // triggering a stop.
-  //
-  // It also means we can set breakpoints on instructions inside an an
-  // if/then block and correctly skip them if we use the BKPT instruction.
-  // The ARM and Thumb BKPT instructions are unconditional even when executed
-  // in a Thumb IT block.
-  //
-  // If your debugger inserts software traps in ARM/Thumb code, it will
-  // need to use 16 and 32 bit instruction for 16 and 32 bit thumb
-  // instructions respectively. If your debugger inserts a 16 bit thumb
-  // trap on top of a 32 bit thumb instruction for an opcode that is inside
-  // an if/then, it will change the it/then to conditionally execute your
-  // 16 bit trap and then cause your program to crash if it executes the
-  // trailing 16 bits (the second half of the 32 bit thumb instruction you
-  // partially overwrote).
-
-  RegisterContextSP reg_ctx_sp(thread.GetRegisterContext());
-  if (reg_ctx_sp) {
-    const uint32_t cpsr = reg_ctx_sp->GetFlags(0);
-    if (cpsr != 0) {
-      // Read the J and T bits to get the ISETSTATE
-      const uint32_t J = Bit32(cpsr, 24);
-      const uint32_t T = Bit32(cpsr, 5);
-      const uint32_t ISETSTATE = J << 1 | T;
-      if (ISETSTATE == 0) {
-// NOTE: I am pretty sure we want to enable the code below
-// that detects when we stop on an instruction in ARM mode
-// that is conditional and the condition doesn't pass. This
-// can happen if you set a breakpoint on an instruction that
-// is conditional. We currently will _always_ stop on the
-// instruction which is bad. You can also run into this while
-// single stepping and you could appear to run code in the "if"
-// and in the "else" clause because it would stop at all of the
-// conditional instructions in both.
-// In such cases, we really don't want to stop at this location.
-// I will check with the lldb-dev list first before I enable this.
-#if 0
-                // ARM mode: check for condition on intsruction
-                const addr_t pc = reg_ctx_sp->GetPC();
-                Status error;
-                // If we fail to read the opcode we will get UINT64_MAX as the
-                // result in "opcode" which we can use to detect if we read a
-                // valid opcode.
-                const uint64_t opcode = thread.GetProcess()->ReadUnsignedIntegerFromMemory(pc, 4, UINT64_MAX, error);
-                if (opcode <= UINT32_MAX)
-                {
-                    const uint32_t condition = Bits32((uint32_t)opcode, 31, 28);
-                    if (!ARMConditionPassed(condition, cpsr))
-                    {
-                        // We ARE stopped on an ARM instruction whose condition doesn't
-                        // pass so this instruction won't get executed.
-                        // Regardless of why it stopped, we need to clear the stop info
-                        thread.SetStopInfo (StopInfoSP());
-                    }
-                }
-#endif
-      } else if (ISETSTATE == 1) {
-        // Thumb mode
-        const uint32_t ITSTATE =
-            Bits32(cpsr, 15, 10) << 2 | Bits32(cpsr, 26, 25);
-        if (ITSTATE != 0) {
-          const uint32_t condition = Bits32(ITSTATE, 7, 4);
-          if (!ARMConditionPassed(condition, cpsr)) {
-            // We ARE stopped in a Thumb IT instruction on an instruction whose
-            // condition doesn't pass so this instruction won't get executed.
-            // Regardless of why it stopped, we need to clear the stop info
-            thread.SetStopInfo(StopInfoSP());
-          }
-        }
-      }
-    }
-  }
-}
-
-ArchSpec::StopInfoOverrideCallbackType
-ArchSpec::GetStopInfoOverrideCallback() const {
-  const llvm::Triple::ArchType machine = GetMachine();
-  if (machine == llvm::Triple::arm)
-    return StopInfoOverrideCallbackTypeARM;
-  return nullptr;
-}
-
 bool ArchSpec::IsFullySpecifiedTriple() const {
   const auto &user_specified_triple = GetTriple();
 
@@ -1623,7 +1522,7 @@ bool ArchSpec::IsFullySpecifiedTriple() const {
 
 void ArchSpec::PiecewiseTripleCompare(
     const ArchSpec &other, bool &arch_different, bool &vendor_different,
-    bool &os_different, bool &os_version_different, bool &env_different) {
+    bool &os_different, bool &os_version_different, bool &env_different) const {
   const llvm::Triple &me(GetTriple());
   const llvm::Triple &them(other.GetTriple());
 
diff --git a/lldb/source/Core/PluginManager.cpp b/lldb/source/Core/PluginManager.cpp
index 9bb615b6a55..a49fbc3f90f 100644
--- a/lldb/source/Core/PluginManager.cpp
+++ b/lldb/source/Core/PluginManager.cpp
@@ -275,6 +275,54 @@ PluginManager::GetABICreateCallbackForPluginName(const ConstString &name) {
   return nullptr;
 }
 
+#pragma mark Architecture
+
+struct ArchitectureInstance {
+  ConstString name;
+  std::string description;
+  PluginManager::ArchitectureCreateInstance create_callback;
+};
+
+typedef std::vector<ArchitectureInstance> ArchitectureInstances;
+
+static std::mutex g_architecture_mutex;
+
+static ArchitectureInstances &GetArchitectureInstances() {
+  static ArchitectureInstances g_instances;
+  return g_instances;
+}
+
+void PluginManager::RegisterPlugin(const ConstString &name,
+                                   llvm::StringRef description,
+                                   ArchitectureCreateInstance create_callback) {
+  std::lock_guard<std::mutex> guard(g_architecture_mutex);
+  GetArchitectureInstances().push_back({name, description, create_callback});
+}
+
+void PluginManager::UnregisterPlugin(
+    ArchitectureCreateInstance create_callback) {
+  std::lock_guard<std::mutex> guard(g_architecture_mutex);
+  auto &instances = GetArchitectureInstances();
+
+  for (auto pos = instances.begin(), end = instances.end(); pos != end; ++pos) {
+    if (pos->create_callback == create_callback) {
+      instances.erase(pos);
+      return;
+    }
+  }
+  llvm_unreachable("Plugin not found");
+}
+
+std::unique_ptr<Architecture>
+PluginManager::CreateArchitectureInstance(const ArchSpec &arch) {
+  std::lock_guard<std::mutex> guard(g_architecture_mutex);
+  for (const auto &instances : GetArchitectureInstances()) {
+    if (auto plugin_up = instances.create_callback(arch))
+      return plugin_up;
+  }
+  return nullptr;
+}
+
 #pragma mark Disassembler
 
 struct DisassemblerInstance {
diff --git a/lldb/source/Plugins/Architecture/Arm/ArchitectureArm.cpp b/lldb/source/Plugins/Architecture/Arm/ArchitectureArm.cpp
new file mode 100644
index 00000000000..219adc5463a
--- /dev/null
+++ b/lldb/source/Plugins/Architecture/Arm/ArchitectureArm.cpp
@@ -0,0 +1,131 @@
+//===-- ArchitectureArm.cpp -------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Plugins/Architecture/Arm/ArchitectureArm.h"
+#include "Plugins/Process/Utility/ARMDefines.h"
+#include "Plugins/Process/Utility/InstructionUtils.h"
+#include "lldb/Core/ArchSpec.h"
+#include "lldb/Core/PluginManager.h"
+#include "lldb/Target/RegisterContext.h"
+#include "lldb/Target/Thread.h"
+
+using namespace lldb_private;
+using namespace lldb;
+
+ConstString ArchitectureArm::GetPluginNameStatic() {
+  return ConstString("arm");
+}
+
+void ArchitectureArm::Initialize() {
+  PluginManager::RegisterPlugin(GetPluginNameStatic(),
+                                "Arm-specific algorithms",
+                                &ArchitectureArm::Create);
+}
+
+void ArchitectureArm::Terminate() {
+  PluginManager::UnregisterPlugin(&ArchitectureArm::Create);
+}
+
+std::unique_ptr<Architecture> ArchitectureArm::Create(const ArchSpec &arch) {
+  if (arch.GetMachine() != llvm::Triple::arm)
+    return nullptr;
+  return std::unique_ptr<Architecture>(new ArchitectureArm());
+}
+
+ConstString ArchitectureArm::GetPluginName() { return GetPluginNameStatic(); }
+uint32_t ArchitectureArm::GetPluginVersion() { return 1; }
+
+void ArchitectureArm::OverrideStopInfo(Thread &thread) {
+  // We need to check if we are stopped in Thumb mode in a IT instruction
+  // and detect if the condition doesn't pass. If this is the case it means
+  // we won't actually execute this instruction. If this happens we need to
+  // clear the stop reason to no thread plans think we are stopped for a
+  // reason and the plans should keep going.
+  //
+  // We do this because when single stepping many ARM processes, debuggers
+  // often use the BVR/BCR registers that says "stop when the PC is not
+  // equal to its current value". This method of stepping means we can end
+  // up stopping on instructions inside an if/then block that wouldn't get
+  // executed. By fixing this we can stop the debugger from seeming like
+  // you stepped through both the "if" _and_ the "else" clause when source
+  // level stepping because the debugger stops regardless due to the BVR/BCR
+  // triggering a stop.
+  //
+  // It also means we can set breakpoints on instructions inside an an
+  // if/then block and correctly skip them if we use the BKPT instruction.
+  // The ARM and Thumb BKPT instructions are unconditional even when executed
+  // in a Thumb IT block.
+  //
+  // If your debugger inserts software traps in ARM/Thumb code, it will
+  // need to use 16 and 32 bit instruction for 16 and 32 bit thumb
+  // instructions respectively. If your debugger inserts a 16 bit thumb
+  // trap on top of a 32 bit thumb instruction for an opcode that is inside
+  // an if/then, it will change the it/then to conditionally execute your
+  // 16 bit trap and then cause your program to crash if it executes the
+  // trailing 16 bits (the second half of the 32 bit thumb instruction you
+  // partially overwrote).
+
+  RegisterContextSP reg_ctx_sp(thread.GetRegisterContext());
+  if (!reg_ctx_sp)
+    return;
+
+  const uint32_t cpsr = reg_ctx_sp->GetFlags(0);
+  if (cpsr == 0)
+    return;
+
+  // Read the J and T bits to get the ISETSTATE
+  const uint32_t J = Bit32(cpsr, 24);
+  const uint32_t T = Bit32(cpsr, 5);
+  const uint32_t ISETSTATE = J << 1 | T;
+  if (ISETSTATE == 0) {
+// NOTE: I am pretty sure we want to enable the code below
+// that detects when we stop on an instruction in ARM mode
+// that is conditional and the condition doesn't pass. This
+// can happen if you set a breakpoint on an instruction that
+// is conditional. We currently will _always_ stop on the
+// instruction which is bad. You can also run into this while
+// single stepping and you could appear to run code in the "if"
+// and in the "else" clause because it would stop at all of the
+// conditional instructions in both.
+// In such cases, we really don't want to stop at this location.
+// I will check with the lldb-dev list first before I enable this.
+#if 0
+    // ARM mode: check for condition on intsruction
+    const addr_t pc = reg_ctx_sp->GetPC();
+    Status error;
+    // If we fail to read the opcode we will get UINT64_MAX as the
+    // result in "opcode" which we can use to detect if we read a
+    // valid opcode.
+    const uint64_t opcode = thread.GetProcess()->ReadUnsignedIntegerFromMemory(pc, 4, UINT64_MAX, error);
+    if (opcode <= UINT32_MAX)
+    {
+        const uint32_t condition = Bits32((uint32_t)opcode, 31, 28);
+        if (!ARMConditionPassed(condition, cpsr))
+        {
+            // We ARE stopped on an ARM instruction whose condition doesn't
+            // pass so this instruction won't get executed.
+            // Regardless of why it stopped, we need to clear the stop info
+            thread.SetStopInfo (StopInfoSP());
+        }
+    }
+#endif
+  } else if (ISETSTATE == 1) {
+    // Thumb mode
+    const uint32_t ITSTATE = Bits32(cpsr, 15, 10) << 2 | Bits32(cpsr, 26, 25);
+    if (ITSTATE != 0) {
+      const uint32_t condition = Bits32(ITSTATE, 7, 4);
+      if (!ARMConditionPassed(condition, cpsr)) {
+        // We ARE stopped in a Thumb IT instruction on an instruction whose
+        // condition doesn't pass so this instruction won't get executed.
+        // Regardless of why it stopped, we need to clear the stop info
+        thread.SetStopInfo(StopInfoSP());
+      }
+    }
+  }
+}
diff --git a/lldb/source/Plugins/Architecture/Arm/ArchitectureArm.h b/lldb/source/Plugins/Architecture/Arm/ArchitectureArm.h
new file mode 100644
index 00000000000..9ce6c69ef27
--- /dev/null
+++ b/lldb/source/Plugins/Architecture/Arm/ArchitectureArm.h
@@ -0,0 +1,35 @@
+//===-- ArchitectureArm.h ---------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLDB_PLUGIN_ARCHITECTURE_ARM_H
+#define LLDB_PLUGIN_ARCHITECTURE_ARM_H
+
+#include "lldb/Core/Architecture.h"
+
+namespace lldb_private {
+
+class ArchitectureArm : public Architecture {
+public:
+  static ConstString GetPluginNameStatic();
+  static void Initialize();
+  static void Terminate();
+
+  ConstString GetPluginName() override;
+  uint32_t GetPluginVersion() override;
+
+  void OverrideStopInfo(Thread &thread) override;
+
+private:
+  static std::unique_ptr<Architecture> Create(const ArchSpec &arch);
+  ArchitectureArm() = default;
+};
+
+} // namespace lldb_private
+
+#endif // LLDB_PLUGIN_ARCHITECTURE_ARM_H
diff --git a/lldb/source/Plugins/Architecture/Arm/CMakeLists.txt b/lldb/source/Plugins/Architecture/Arm/CMakeLists.txt
new file mode 100644
index 00000000000..b9de3bd8903
--- /dev/null
+++ b/lldb/source/Plugins/Architecture/Arm/CMakeLists.txt
@@ -0,0 +1,10 @@
+add_lldb_library(lldbPluginArchitectureArm PLUGIN
+  ArchitectureArm.cpp
+
+  LINK_LIBS
+    lldbPluginProcessUtility
+    lldbCore
+    lldbTarget
+  LINK_COMPONENTS
+    Support
+  )
diff --git a/lldb/source/Plugins/Architecture/CMakeLists.txt b/lldb/source/Plugins/Architecture/CMakeLists.txt
new file mode 100644
index 00000000000..5abaa8e6823
--- /dev/null
+++ b/lldb/source/Plugins/Architecture/CMakeLists.txt
@@ -0,0 +1 @@
+add_subdirectory(Arm)
diff --git a/lldb/source/Plugins/CMakeLists.txt b/lldb/source/Plugins/CMakeLists.txt
index ac1afcbc331..5092b210a12 100644
--- a/lldb/source/Plugins/CMakeLists.txt
+++ b/lldb/source/Plugins/CMakeLists.txt
@@ -1,4 +1,5 @@
 add_subdirectory(ABI)
+add_subdirectory(Architecture)
 add_subdirectory(Disassembler)
 add_subdirectory(DynamicLoader)
 add_subdirectory(ExpressionParser)
diff --git a/lldb/source/Target/Process.cpp b/lldb/source/Target/Process.cpp
index 16f56881dcb..6540b906477 100644
--- a/lldb/source/Target/Process.cpp
+++ b/lldb/source/Target/Process.cpp
@@ -743,8 +743,7 @@ Process::Process(lldb::TargetSP target_sp, ListenerSP listener_sp,
       m_profile_data_comm_mutex(), m_profile_data(), m_iohandler_sync(0),
       m_memory_cache(*this), m_allocated_memory_cache(*this),
       m_should_detach(false), m_next_event_action_ap(), m_public_run_lock(),
-      m_private_run_lock(), m_stop_info_override_callback(nullptr),
-      m_finalizing(false), m_finalize_called(false),
+      m_private_run_lock(), m_finalizing(false), m_finalize_called(false),
       m_clear_thread_plans_on_stop(false), m_force_next_event_delivery(false),
       m_last_broadcast_state(eStateInvalid), m_destroy_in_process(false),
       m_can_interpret_function_calls(false), m_warnings_issued(),
@@ -871,7 +870,6 @@ void Process::Finalize() {
   m_language_runtimes.clear();
   m_instrumentation_runtimes.clear();
   m_next_event_action_ap.reset();
-  m_stop_info_override_callback = nullptr;
   // Clear the last natural stop ID since it has a strong
   // reference to this process
   m_mod_id.SetStopEventForLastNaturalStopID(EventSP());
@@ -2720,7 +2718,6 @@ Status Process::Launch(ProcessLaunchInfo &launch_info) {
   m_system_runtime_ap.reset();
   m_os_ap.reset();
   m_process_input_reader.reset();
-  m_stop_info_override_callback = nullptr;
 
   Module *exe_module = GetTarget().GetExecutableModulePointer();
   if (exe_module) {
@@ -2808,9 +2805,6 @@ Status Process::Launch(ProcessLaunchInfo &launch_info) {
             else
               StartPrivateStateThread();
 
-            m_stop_info_override_callback =
-                GetTarget().GetArchitecture().GetStopInfoOverrideCallback();
-
             // Target was stopped at entry as was intended. Need to notify the
             // listeners
             // about it.
@@ -2994,7 +2988,6 @@ Status Process::Attach(ProcessAttachInfo &attach_info) {
   m_jit_loaders_ap.reset();
   m_system_runtime_ap.reset();
   m_os_ap.reset();
-  m_stop_info_override_callback = nullptr;
 
   lldb::pid_t attach_pid = attach_info.GetProcessID();
   Status error;
@@ -3227,8 +3220,6 @@ void Process::CompleteAttach() {
                         : "<none>");
     }
   }
-
-  m_stop_info_override_callback = process_arch.GetStopInfoOverrideCallback();
 }
 
 Status Process::ConnectRemote(Stream *strm, llvm::StringRef remote_url) {
@@ -5857,7 +5848,6 @@ void Process::DidExec() {
   m_instrumentation_runtimes.clear();
   m_thread_list.DiscardThreadPlans();
   m_memory_cache.Clear(true);
-  m_stop_info_override_callback = nullptr;
   DoDidExec();
   CompleteAttach();
   // Flush the process (threads and all stack frames) after running
diff --git a/lldb/source/Target/Target.cpp b/lldb/source/Target/Target.cpp
index a548911e2fc..bd60a7d98ff 100644
--- a/lldb/source/Target/Target.cpp
+++ b/lldb/source/Target/Target.cpp
@@ -26,6 +26,7 @@
 #include "lldb/Core/Event.h"
 #include "lldb/Core/Module.h"
 #include "lldb/Core/ModuleSpec.h"
+#include "lldb/Core/PluginManager.h"
 #include "lldb/Core/Section.h"
 #include "lldb/Core/SourceManager.h"
 #include "lldb/Core/State.h"
@@ -65,6 +66,16 @@ using namespace lldb_private;
 
 constexpr std::chrono::milliseconds EvaluateExpressionOptions::default_timeout;
 
+Target::Arch::Arch(const ArchSpec &spec)
+    : m_spec(spec),
+      m_plugin_up(PluginManager::CreateArchitectureInstance(spec)) {}
+
+const Target::Arch& Target::Arch::operator=(const ArchSpec &spec) {
+  m_spec = spec;
+  m_plugin_up = PluginManager::CreateArchitectureInstance(spec);
+  return *this;
+}
+
 ConstString &Target::GetStaticBroadcasterClass() {
   static ConstString class_name("lldb.target");
   return class_name;
@@ -76,12 +87,12 @@ Target::Target(Debugger &debugger, const ArchSpec &target_arch,
       Broadcaster(debugger.GetBroadcasterManager(),
                   Target::GetStaticBroadcasterClass().AsCString()),
       ExecutionContextScope(), m_debugger(debugger), m_platform_sp(platform_sp),
-      m_mutex(), m_arch(target_arch), m_images(this), m_section_load_history(),
-      m_breakpoint_list(false), m_internal_breakpoint_list(true),
-      m_watchpoint_list(), m_process_sp(), m_search_filter_sp(),
-      m_image_search_paths(ImageSearchPathsChanged, this), m_ast_importer_sp(),
-      m_source_manager_ap(), m_stop_hooks(), m_stop_hook_next_id(0),
-      m_valid(true), m_suppress_stop_hooks(false),
+      m_mutex(), m_arch(target_arch),
+      m_images(this), m_section_load_history(), m_breakpoint_list(false),
+      m_internal_breakpoint_list(true), m_watchpoint_list(), m_process_sp(),
+      m_search_filter_sp(), m_image_search_paths(ImageSearchPathsChanged, this),
+      m_ast_importer_sp(), m_source_manager_ap(), m_stop_hooks(),
+      m_stop_hook_next_id(0), m_valid(true), m_suppress_stop_hooks(false),
       m_is_dummy_target(is_dummy_target)
 
 {
@@ -96,10 +107,11 @@ Target::Target(Debugger &debugger, const ArchSpec &target_arch,
   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_OBJECT));
   if (log)
     log->Printf("%p Target::Target()", static_cast<void *>(this));
-  if (m_arch.IsValid()) {
-    LogIfAnyCategoriesSet(
-        LIBLLDB_LOG_TARGET, "Target::Target created with architecture %s (%s)",
-        m_arch.GetArchitectureName(), m_arch.GetTriple().getTriple().c_str());
+  if (target_arch.IsValid()) {
+    LogIfAnyCategoriesSet(LIBLLDB_LOG_TARGET,
+                          "Target::Target created with architecture %s (%s)",
+                          target_arch.GetArchitectureName(),
+                          target_arch.GetTriple().getTriple().c_str());
   }
 }
 
@@ -250,7 +262,7 @@ void Target::Destroy() {
   m_valid = false;
   DeleteCurrentProcess();
   m_platform_sp.reset();
-  m_arch.Clear();
+  m_arch = ArchSpec();
   ClearModules(true);
   m_section_load_history.Clear();
   const bool notify = false;
@@ -1366,8 +1378,8 @@ void Target::ClearModules(bool delete_locations) {
 
 void Target::DidExec() {
   // When a process exec's we need to know about it so we can do some cleanup.
-  m_breakpoint_list.RemoveInvalidLocations(m_arch);
-  m_internal_breakpoint_list.RemoveInvalidLocations(m_arch);
+  m_breakpoint_list.RemoveInvalidLocations(m_arch.GetSpec());
+  m_internal_breakpoint_list.RemoveInvalidLocations(m_arch.GetSpec());
 }
 
 void Target::SetExecutableModule(ModuleSP &executable_sp,
@@ -1385,13 +1397,12 @@ void Target::SetExecutableModule(ModuleSP &executable_sp,
 
     // If we haven't set an architecture yet, reset our architecture based on
     // what we found in the executable module.
-    if (!m_arch.IsValid()) {
+    if (!m_arch.GetSpec().IsValid()) {
       m_arch = executable_sp->GetArchitecture();
-      if (log)
-        log->Printf("Target::SetExecutableModule setting architecture to %s "
-                    "(%s) based on executable file",
-                    m_arch.GetArchitectureName(),
-                    m_arch.GetTriple().getTriple().c_str());
+      LLDB_LOG(log,
+               "setting architecture to {0} ({1}) based on executable file",
+               m_arch.GetSpec().GetArchitectureName(),
+               m_arch.GetSpec().GetTriple().getTriple());
     }
 
     FileSpecList dependent_files;
@@ -1409,7 +1420,7 @@ void Target::SetExecutableModule(ModuleSP &executable_sp,
         else
           platform_dependent_file_spec = dependent_file_spec;
 
-        ModuleSpec module_spec(platform_dependent_file_spec, m_arch);
+        ModuleSpec module_spec(platform_dependent_file_spec, m_arch.GetSpec());
         ModuleSP image_module_sp(GetSharedModule(module_spec));
         if (image_module_sp) {
           ObjectFile *objfile = image_module_sp->GetObjectFile();
@@ -1423,21 +1434,21 @@ void Target::SetExecutableModule(ModuleSP &executable_sp,
 
 bool Target::SetArchitecture(const ArchSpec &arch_spec) {
   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_TARGET));
-  bool missing_local_arch = !m_arch.IsValid();
+  bool missing_local_arch = !m_arch.GetSpec().IsValid();
   bool replace_local_arch = true;
   bool compatible_local_arch = false;
   ArchSpec other(arch_spec);
 
   if (!missing_local_arch) {
-    if (m_arch.IsCompatibleMatch(arch_spec)) {
-      other.MergeFrom(m_arch);
+    if (m_arch.GetSpec().IsCompatibleMatch(arch_spec)) {
+      other.MergeFrom(m_arch.GetSpec());
 
-      if (m_arch.IsCompatibleMatch(other)) {
+      if (m_arch.GetSpec().IsCompatibleMatch(other)) {
         compatible_local_arch = true;
         bool arch_changed, vendor_changed, os_changed, os_ver_changed,
             env_changed;
 
-        m_arch.PiecewiseTripleCompare(other, arch_changed, vendor_changed,
+        m_arch.GetSpec().PiecewiseTripleCompare(other, arch_changed, vendor_changed,
                                       os_changed, os_ver_changed, env_changed);
 
         if (!arch_changed && !vendor_changed && !os_changed && !env_changed)
@@ -1451,10 +1462,9 @@ bool Target::SetArchitecture(const ArchSpec &arch_spec) {
     // update the architecture, unless the one we already have is more specified
     if (replace_local_arch)
       m_arch = other;
-    if (log)
-      log->Printf("Target::SetArchitecture set architecture to %s (%s)",
-                  m_arch.GetArchitectureName(),
-                  m_arch.GetTriple().getTriple().c_str());
+    LLDB_LOG(log, "set architecture to {0} ({1})",
+             m_arch.GetSpec().GetArchitectureName(),
+             m_arch.GetSpec().GetTriple().getTriple());
     return true;
   }
 
@@ -1491,12 +1501,12 @@ bool Target::SetArchitecture(const ArchSpec &arch_spec) {
 
 bool Target::MergeArchitecture(const ArchSpec &arch_spec) {
   if (arch_spec.IsValid()) {
-    if (m_arch.IsCompatibleMatch(arch_spec)) {
+    if (m_arch.GetSpec().IsCompatibleMatch(arch_spec)) {
       // The current target arch is compatible with "arch_spec", see if we
       // can improve our current architecture using bits from "arch_spec"
 
       // Merge bits from arch_spec into "merged_arch" and set our architecture
-      ArchSpec merged_arch(m_arch);
+      ArchSpec merged_arch(m_arch.GetSpec());
       merged_arch.MergeFrom(arch_spec);
       return SetArchitecture(merged_arch);
     } else {
@@ -1824,8 +1834,8 @@ size_t Target::ReadScalarIntegerFromMemory(const Address &addr,
     size_t bytes_read =
         ReadMemory(addr, prefer_file_cache, &uval, byte_size, error);
     if (bytes_read == byte_size) {
-      DataExtractor data(&uval, sizeof(uval), m_arch.GetByteOrder(),
-                         m_arch.GetAddressByteSize());
+      DataExtractor data(&uval, sizeof(uval), m_arch.GetSpec().GetByteOrder(),
+                         m_arch.GetSpec().GetAddressByteSize());
       lldb::offset_t offset = 0;
       if (byte_size <= 4)
         scalar = data.GetMaxU32(&offset, byte_size);
@@ -1859,7 +1869,7 @@ bool Target::ReadPointerFromMemory(const Address &addr, bool prefer_file_cache,
                                    Status &error, Address &pointer_addr) {
   Scalar scalar;
   if (ReadScalarIntegerFromMemory(addr, prefer_file_cache,
-                                  m_arch.GetAddressByteSize(), false, scalar,
+                                  m_arch.GetSpec().GetAddressByteSize(), false, scalar,
                                   error)) {
     addr_t pointer_vm_addr = scalar.ULongLong(LLDB_INVALID_ADDRESS);
     if (pointer_vm_addr != LLDB_INVALID_ADDRESS) {
@@ -2352,7 +2362,7 @@ lldb::addr_t Target::GetPersistentSymbol(const ConstString &name) {
 lldb::addr_t Target::GetCallableLoadAddress(lldb::addr_t load_addr,
                                             AddressClass addr_class) const {
   addr_t code_addr = load_addr;
-  switch (m_arch.GetMachine()) {
+  switch (m_arch.GetSpec().GetMachine()) {
   case llvm::Triple::mips:
   case llvm::Triple::mipsel:
   case llvm::Triple::mips64:
@@ -2411,7 +2421,7 @@ lldb::addr_t Target::GetCallableLoadAddress(lldb::addr_t load_addr,
 lldb::addr_t Target::GetOpcodeLoadAddress(lldb::addr_t load_addr,
                                           AddressClass addr_class) const {
   addr_t opcode_addr = load_addr;
-  switch (m_arch.GetMachine()) {
+  switch (m_arch.GetSpec().GetMachine()) {
   case llvm::Triple::mips:
   case llvm::Triple::mipsel:
   case llvm::Triple::mips64:
@@ -2443,7 +2453,7 @@ lldb::addr_t Target::GetBreakableLoadAddress(lldb::addr_t addr) {
   addr_t breakable_addr = addr;
   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_BREAKPOINTS));
 
-  switch (m_arch.GetMachine()) {
+  switch (m_arch.GetSpec().GetMachine()) {
   default:
     break;
   case llvm::Triple::mips:
@@ -2454,7 +2464,7 @@ lldb::addr_t Target::GetBreakableLoadAddress(lldb::addr_t addr) {
     addr_t current_offset = 0;
     uint32_t loop_count = 0;
     Address resolved_addr;
-    uint32_t arch_flags = m_arch.GetFlags();
+    uint32_t arch_flags = m_arch.GetSpec().GetFlags();
     bool IsMips16 = arch_flags & ArchSpec::eMIPSAse_mips16;
     bool IsMicromips = arch_flags & ArchSpec::eMIPSAse_micromips;
     SectionLoadList &section_load_list = GetSectionLoadList();
@@ -2507,7 +2517,7 @@ lldb::addr_t Target::GetBreakableLoadAddress(lldb::addr_t addr) {
 
     // Create Disassembler Instance
     lldb::DisassemblerSP disasm_sp(
-        Disassembler::FindPlugin(m_arch, nullptr, nullptr));
+        Disassembler::FindPlugin(m_arch.GetSpec(), nullptr, nullptr));
 
     ExecutionContext exe_ctx;
     CalculateExecutionContext(exe_ctx);
diff --git a/lldb/source/Target/Thread.cpp b/lldb/source/Target/Thread.cpp
index 515c41fd99f..217cbccedf6 100644
--- a/lldb/source/Target/Thread.cpp
+++ b/lldb/source/Target/Thread.cpp
@@ -442,10 +442,9 @@ lldb::StopInfoSP Thread::GetPrivateStopInfo() {
     if (m_stop_info_override_stop_id != process_stop_id) {
       m_stop_info_override_stop_id = process_stop_id;
       if (m_stop_info_sp) {
-        ArchSpec::StopInfoOverrideCallbackType callback =
-            GetProcess()->GetStopInfoOverrideCallback();
-        if (callback)
-          callback(*this);
+        if (Architecture *arch =
+                process_sp->GetTarget().GetArchitecturePlugin())
+          arch->OverrideStopInfo(*this);
       }
     }
   }