/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "instrumentation.h"

#include <functional>
#include <optional>
#include <sstream>

#include <android-base/logging.h>

#include "arch/context.h"
#include "art_field-inl.h"
#include "art_method-inl.h"
#include "base/atomic.h"
#include "base/callee_save_type.h"
#include "class_linker.h"
#include "debugger.h"
#include "dex/dex_file-inl.h"
#include "dex/dex_file_types.h"
#include "dex/dex_instruction-inl.h"
#include "entrypoints/quick/quick_alloc_entrypoints.h"
#include "entrypoints/quick/quick_entrypoints.h"
#include "entrypoints/runtime_asm_entrypoints.h"
#include "gc_root-inl.h"
#include "interpreter/interpreter.h"
#include "interpreter/interpreter_common.h"
#include "jit/jit.h"
#include "jit/jit_code_cache.h"
#include "jvalue-inl.h"
#include "jvalue.h"
#include "mirror/class-inl.h"
#include "mirror/dex_cache.h"
#include "mirror/object-inl.h"
#include "mirror/object_array-inl.h"
#include "nterp_helpers.h"
#include "nth_caller_visitor.h"
#include "oat_file_manager.h"
#include "oat_quick_method_header.h"
#include "runtime-inl.h"
#include "thread.h"
#include "thread_list.h"

namespace art {
namespace instrumentation {

constexpr bool kVerboseInstrumentation = false;

void InstrumentationListener::MethodExited(
    Thread* thread,
    ArtMethod* method,
    OptionalFrame frame,
    MutableHandle<mirror::Object>& return_value) {
  DCHECK_EQ(method->GetInterfaceMethodIfProxy(kRuntimePointerSize)->GetReturnTypePrimitive(),
            Primitive::kPrimNot);
  const void* original_ret = return_value.Get();
  JValue v;
  v.SetL(return_value.Get());
  MethodExited(thread, method, frame, v);
  DCHECK(original_ret == v.GetL()) << "Return value changed";
}

void InstrumentationListener::FieldWritten(Thread* thread,
                                           Handle<mirror::Object> this_object,
                                           ArtMethod* method,
                                           uint32_t dex_pc,
                                           ArtField* field,
                                           Handle<mirror::Object> field_value) {
  DCHECK(!field->IsPrimitiveType());
  JValue v;
  v.SetL(field_value.Get());
  FieldWritten(thread, this_object, method, dex_pc, field, v);
}

// Instrumentation works on non-inlined frames by updating returned PCs
// of compiled frames.
static constexpr StackVisitor::StackWalkKind kInstrumentationStackWalk =
    StackVisitor::StackWalkKind::kSkipInlinedFrames;

class InstallStubsClassVisitor : public ClassVisitor {
 public:
  explicit InstallStubsClassVisitor(Instrumentation* instrumentation)
      : instrumentation_(instrumentation) {}

  bool operator()(ObjPtr<mirror::Class> klass) override REQUIRES(Locks::mutator_lock_) {
    instrumentation_->InstallStubsForClass(klass.Ptr());
    return true;  // we visit all classes.
  }

 private:
  Instrumentation* const instrumentation_;
};

InstrumentationStackPopper::InstrumentationStackPopper(Thread* self)
      : self_(self),
        instrumentation_(Runtime::Current()->GetInstrumentation()),
        pop_until_(0u) {}

InstrumentationStackPopper::~InstrumentationStackPopper() {
  std::map<uintptr_t, instrumentation::InstrumentationStackFrame>* stack =
      self_->GetInstrumentationStack();
  for (auto i = stack->begin(); i != stack->end() && i->first <= pop_until_;) {
    i = stack->erase(i);
  }
}

bool InstrumentationStackPopper::PopFramesTo(uintptr_t stack_pointer,
                                             MutableHandle<mirror::Throwable>& exception) {
  std::map<uintptr_t, instrumentation::InstrumentationStackFrame>* stack =
      self_->GetInstrumentationStack();
  DCHECK(!self_->IsExceptionPending());
  if (!instrumentation_->HasMethodUnwindListeners()) {
    pop_until_ = stack_pointer;
    return true;
  }
  if (kVerboseInstrumentation) {
    LOG(INFO) << "Popping frames for exception " << exception->Dump();
  }
  // The instrumentation events expect the exception to be set.
  self_->SetException(exception.Get());
  bool new_exception_thrown = false;
  auto i = stack->upper_bound(pop_until_);

  // Now pop all frames until reaching stack_pointer, or a new exception is
  // thrown. Note that `stack_pointer` doesn't need to be a return PC address
  // (in fact the exception handling code passes the start of the frame where
  // the catch handler is).
  for (; i != stack->end() && i->first <= stack_pointer; i++) {
    const InstrumentationStackFrame& frame = i->second;
    ArtMethod* method = frame.method_;
    // Notify listeners of method unwind.
    // TODO: improve the dex_pc information here.
    uint32_t dex_pc = dex::kDexNoIndex;
    if (kVerboseInstrumentation) {
      LOG(INFO) << "Popping for unwind " << method->PrettyMethod();
    }
    if (!method->IsRuntimeMethod() && !frame.interpreter_entry_) {
      instrumentation_->MethodUnwindEvent(self_, frame.this_object_, method, dex_pc);
      new_exception_thrown = self_->GetException() != exception.Get();
      if (new_exception_thrown) {
        pop_until_ = i->first;
        break;
      }
    }
  }
  if (!new_exception_thrown) {
    pop_until_ = stack_pointer;
  }
  exception.Assign(self_->GetException());
  self_->ClearException();
  if (kVerboseInstrumentation && new_exception_thrown) {
    LOG(INFO) << "Did partial pop of frames due to new exception";
  }
  return !new_exception_thrown;
}

Instrumentation::Instrumentation()
    : current_force_deopt_id_(0),
      instrumentation_stubs_installed_(false),
      instrumentation_level_(InstrumentationLevel::kInstrumentNothing),
      forced_interpret_only_(false),
      have_method_entry_listeners_(false),
      have_method_exit_listeners_(false),
      have_method_unwind_listeners_(false),
      have_dex_pc_listeners_(false),
      have_field_read_listeners_(false),
      have_field_write_listeners_(false),
      have_exception_thrown_listeners_(false),
      have_watched_frame_pop_listeners_(false),
      have_branch_listeners_(false),
      have_exception_handled_listeners_(false),
      deoptimized_methods_lock_(new ReaderWriterMutex("deoptimized methods lock",
                                                      kGenericBottomLock)),
      quick_alloc_entry_points_instrumentation_counter_(0),
      alloc_entrypoints_instrumented_(false) {
}

void Instrumentation::InstallStubsForClass(ObjPtr<mirror::Class> klass) {
  if (!klass->IsResolved()) {
    // We need the class to be resolved to install/uninstall stubs. Otherwise its methods
    // could not be initialized or linked with regards to class inheritance.
  } else if (klass->IsErroneousResolved()) {
    // We can't execute code in a erroneous class: do nothing.
  } else {
    for (ArtMethod& method : klass->GetMethods(kRuntimePointerSize)) {
      InstallStubsForMethod(&method);
    }
  }
}

static bool CanHandleInitializationCheck(const void* code) {
  ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
  return class_linker->IsQuickResolutionStub(code) ||
         class_linker->IsQuickToInterpreterBridge(code) ||
         class_linker->IsQuickGenericJniStub(code) ||
         (code == GetQuickInstrumentationEntryPoint());
}

static bool IsProxyInit(ArtMethod* method) REQUIRES_SHARED(Locks::mutator_lock_) {
  // Annoyingly this can be called before we have actually initialized WellKnownClasses so therefore
  // we also need to check this based on the declaring-class descriptor. The check is valid because
  // Proxy only has a single constructor.
  ArtMethod* well_known_proxy_init = jni::DecodeArtMethod(
      WellKnownClasses::java_lang_reflect_Proxy_init);
  if (well_known_proxy_init == method) {
    return true;
  }

  if (well_known_proxy_init != nullptr) {
    return false;
  }

  return method->IsConstructor() &&
      method->GetDeclaringClass()->DescriptorEquals("Ljava/lang/reflect/Proxy;");
}

static void UpdateEntryPoints(ArtMethod* method, const void* quick_code)
    REQUIRES_SHARED(Locks::mutator_lock_) {
  if (kIsDebugBuild) {
    if (NeedsClinitCheckBeforeCall(method) &&
        !method->GetDeclaringClass()->IsVisiblyInitialized()) {
      CHECK(CanHandleInitializationCheck(quick_code));
    }
    jit::Jit* jit = Runtime::Current()->GetJit();
    if (jit != nullptr && jit->GetCodeCache()->ContainsPc(quick_code)) {
      // Ensure we always have the thumb entrypoint for JIT on arm32.
      if (kRuntimeISA == InstructionSet::kArm) {
        CHECK_EQ(reinterpret_cast<uintptr_t>(quick_code) & 1, 1u);
      }
    }
    if (IsProxyInit(method)) {
      CHECK_NE(quick_code, GetQuickInstrumentationEntryPoint());
    }
  }
  // If the method is from a boot image, don't dirty it if the entrypoint
  // doesn't change.
  if (method->GetEntryPointFromQuickCompiledCode() != quick_code) {
    method->SetEntryPointFromQuickCompiledCode(quick_code);
  }
}

bool Instrumentation::CodeNeedsEntryExitStub(const void* code, ArtMethod* method)
    REQUIRES_SHARED(Locks::mutator_lock_) {
  // Proxy.init should never have entry/exit stubs.
  if (IsProxyInit(method)) {
    return false;
  }

  // In some tests runtime isn't setup fully and hence the entry points could
  // be nullptr.
  if (code == nullptr) {
    return true;
  }

  // Code running in the interpreter doesn't need entry/exit stubs.
  if (Runtime::Current()->GetClassLinker()->IsQuickToInterpreterBridge(code)) {
    return false;
  }

  // When jiting code for debuggable apps we generate the code to call method
  // entry / exit hooks when required. Hence it is not required to update
  // to instrumentation entry point for JITed code in debuggable mode.
  if (!Runtime::Current()->IsJavaDebuggable()) {
    return true;
  }

  // Native functions can have JITed entry points but we don't include support
  // for calling entry / exit hooks directly from the JITed code for native
  // functions. So we still have to install entry exit stubs for such cases.
  if (method->IsNative()) {
    return true;
  }

  jit::Jit* jit = Runtime::Current()->GetJit();
  if (jit != nullptr && jit->GetCodeCache()->ContainsPc(code)) {
    return false;
  }
  return true;
}

bool Instrumentation::InterpretOnly(ArtMethod* method) REQUIRES_SHARED(Locks::mutator_lock_) {
  if (method->IsNative()) {
    return false;
  }
  return InterpretOnly() ||
         IsDeoptimized(method) ||
         Runtime::Current()->GetRuntimeCallbacks()->IsMethodBeingInspected(method);
}

static bool CanUseAotCode(ArtMethod* method, const void* quick_code)
    REQUIRES_SHARED(Locks::mutator_lock_) {
  if (quick_code == nullptr) {
    return false;
  }
  if (method->IsNative()) {
    // AOT code for native methods can always be used.
    return true;
  }

  Runtime* runtime = Runtime::Current();
  // For simplicity, we never use AOT code for debuggable.
  if (runtime->IsJavaDebuggable()) {
    return false;
  }

  if (runtime->IsNativeDebuggable()) {
    DCHECK(runtime->UseJitCompilation() && runtime->GetJit()->JitAtFirstUse());
    // If we are doing native debugging, ignore application's AOT code,
    // since we want to JIT it (at first use) with extra stackmaps for native
    // debugging. We keep however all AOT code from the boot image,
    // since the JIT-at-first-use is blocking and would result in non-negligible
    // startup performance impact.
    return runtime->GetHeap()->IsInBootImageOatFile(quick_code);
  }

  return true;
}

static bool CanUseNterp(ArtMethod* method) REQUIRES_SHARED(Locks::mutator_lock_) {
  return interpreter::CanRuntimeUseNterp() &&
      CanMethodUseNterp(method) &&
      method->GetDeclaringClass()->IsVerified();
}

static const void* GetOptimizedCodeFor(ArtMethod* method) REQUIRES_SHARED(Locks::mutator_lock_) {
  DCHECK(!Runtime::Current()->GetInstrumentation()->InterpretOnly(method));
  CHECK(method->IsInvokable()) << method->PrettyMethod();
  if (method->IsProxyMethod()) {
    return GetQuickProxyInvokeHandler();
  }

  // In debuggable mode, we can only use AOT code for native methods.
  ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
  const void* aot_code = method->GetOatMethodQuickCode(class_linker->GetImagePointerSize());
  if (CanUseAotCode(method, aot_code)) {
    return aot_code;
  }

  // If the method has been precompiled, there can be a JIT version.
  jit::Jit* jit = Runtime::Current()->GetJit();
  if (jit != nullptr) {
    const void* code = jit->GetCodeCache()->GetSavedEntryPointOfPreCompiledMethod(method);
    if (code != nullptr) {
      return code;
    }
  }

  // We need to check if the class has been verified for setting up nterp, as
  // the verifier could punt the method to the switch interpreter in case we
  // need to do lock counting.
  if (CanUseNterp(method)) {
    return interpreter::GetNterpEntryPoint();
  }

  return method->IsNative() ? GetQuickGenericJniStub() : GetQuickToInterpreterBridge();
}

void Instrumentation::InitializeMethodsCode(ArtMethod* method, const void* aot_code)
    REQUIRES_SHARED(Locks::mutator_lock_) {
  // Use instrumentation entrypoints if instrumentation is installed.
  if (UNLIKELY(EntryExitStubsInstalled()) && !IsProxyInit(method)) {
    if (!method->IsNative() && InterpretOnly()) {
      UpdateEntryPoints(method, GetQuickToInterpreterBridge());
    } else {
      UpdateEntryPoints(method, GetQuickInstrumentationEntryPoint());
    }
    return;
  }

  if (UNLIKELY(IsForcedInterpretOnly())) {
    UpdateEntryPoints(
        method, method->IsNative() ? GetQuickGenericJniStub() : GetQuickToInterpreterBridge());
    return;
  }

  // Special case if we need an initialization check.
  if (NeedsClinitCheckBeforeCall(method) && !method->GetDeclaringClass()->IsVisiblyInitialized()) {
    // If we have code but the method needs a class initialization check before calling
    // that code, install the resolution stub that will perform the check.
    // It will be replaced by the proper entry point by ClassLinker::FixupStaticTrampolines
    // after initializing class (see ClassLinker::InitializeClass method).
    // Note: this mimics the logic in image_writer.cc that installs the resolution
    // stub only if we have compiled code or we can execute nterp, and the method needs a class
    // initialization check.
    if (aot_code != nullptr || method->IsNative() || CanUseNterp(method)) {
      UpdateEntryPoints(method, GetQuickResolutionStub());
    } else {
      UpdateEntryPoints(method, GetQuickToInterpreterBridge());
    }
    return;
  }

  // Use the provided AOT code if possible.
  if (CanUseAotCode(method, aot_code)) {
    UpdateEntryPoints(method, aot_code);
    return;
  }

  // We check if the class is verified as we need the slow interpreter for lock verification.
  // If the class is not verified, This will be updated in
  // ClassLinker::UpdateClassAfterVerification.
  if (CanUseNterp(method)) {
    UpdateEntryPoints(method, interpreter::GetNterpEntryPoint());
    return;
  }

  // Use default entrypoints.
  UpdateEntryPoints(
      method, method->IsNative() ? GetQuickGenericJniStub() : GetQuickToInterpreterBridge());
}

void Instrumentation::InstallStubsForMethod(ArtMethod* method) {
  if (!method->IsInvokable() || method->IsProxyMethod()) {
    // Do not change stubs for these methods.
    return;
  }
  // Don't stub Proxy.<init>. Note that the Proxy class itself is not a proxy class.
  // TODO We should remove the need for this since it means we cannot always correctly detect calls
  // to Proxy.<init>
  if (IsProxyInit(method)) {
    return;
  }

  // If the instrumentation needs to go through the interpreter, just update the
  // entrypoint to interpreter.
  if (InterpretOnly(method)) {
    UpdateEntryPoints(method, GetQuickToInterpreterBridge());
    return;
  }

  if (EntryExitStubsInstalled()) {
    // Install the instrumentation entry point if needed.
    if (CodeNeedsEntryExitStub(method->GetEntryPointFromQuickCompiledCode(), method)) {
      UpdateEntryPoints(method, GetQuickInstrumentationEntryPoint());
    }
    return;
  }

  // We're being asked to restore the entrypoints after instrumentation.
  CHECK_EQ(instrumentation_level_, InstrumentationLevel::kInstrumentNothing);
  // We need to have the resolution stub still if the class is not initialized.
  if (NeedsClinitCheckBeforeCall(method) && !method->GetDeclaringClass()->IsVisiblyInitialized()) {
    UpdateEntryPoints(method, GetQuickResolutionStub());
    return;
  }
  UpdateEntryPoints(method, GetOptimizedCodeFor(method));
}

// Places the instrumentation exit pc as the return PC for every quick frame. This also allows
// deoptimization of quick frames to interpreter frames. When force_deopt is
// true the frames have to be deoptimized. If the frame has a deoptimization
// stack slot (all Jited frames), it is set to true to indicate this. For frames
// that do not have this slot, the force_deopt_id on the InstrumentationStack is
// used to check if the frame needs to be deoptimized. When force_deopt is false
// we just instrument the stack for method entry / exit hooks.
// Since we may already have done this previously, we need to push new instrumentation frame before
// existing instrumentation frames.
void InstrumentationInstallStack(Thread* thread, void* arg, bool deopt_all_frames)
    REQUIRES(Locks::mutator_lock_) {
  Locks::mutator_lock_->AssertExclusiveHeld(Thread::Current());
  struct InstallStackVisitor final : public StackVisitor {
    InstallStackVisitor(Thread* thread_in,
                        Context* context,
                        uintptr_t instrumentation_exit_pc,
                        uint64_t force_deopt_id,
                        bool deopt_all_frames)
        : StackVisitor(thread_in, context, kInstrumentationStackWalk),
          instrumentation_stack_(thread_in->GetInstrumentationStack()),
          instrumentation_exit_pc_(instrumentation_exit_pc),
          reached_existing_instrumentation_frames_(false),
          force_deopt_id_(force_deopt_id),
          deopt_all_frames_(deopt_all_frames) {}

    bool VisitFrame() override REQUIRES_SHARED(Locks::mutator_lock_) {
      ArtMethod* m = GetMethod();
      if (m == nullptr) {
        if (kVerboseInstrumentation) {
          LOG(INFO) << "  Skipping upcall. Frame " << GetFrameId();
        }
        return true;  // Ignore upcalls.
      }
      if (GetCurrentQuickFrame() == nullptr) {
        bool interpreter_frame = true;
        InstrumentationStackFrame instrumentation_frame(GetThisObject().Ptr(),
                                                        m,
                                                        /*return_pc=*/ 0,
                                                        GetFrameId(),
                                                        interpreter_frame,
                                                        force_deopt_id_);
        if (kVerboseInstrumentation) {
          LOG(INFO) << "Pushing shadow frame " << instrumentation_frame.Dump();
        }
        shadow_stack_.push_back(instrumentation_frame);
        return true;  // Continue.
      }
      uintptr_t return_pc = GetReturnPc();
      if (kVerboseInstrumentation) {
        LOG(INFO) << "  Installing exit stub in " << DescribeLocation();
      }
      if (return_pc == instrumentation_exit_pc_) {
        auto it = instrumentation_stack_->find(GetReturnPcAddr());
        CHECK(it != instrumentation_stack_->end());
        const InstrumentationStackFrame& frame = it->second;
        if (m->IsRuntimeMethod()) {
          if (frame.interpreter_entry_) {
            return true;
          }
        }

        // We've reached a frame which has already been installed with instrumentation exit stub.
        // We should have already installed instrumentation or be interpreter on previous frames.
        reached_existing_instrumentation_frames_ = true;

        CHECK_EQ(m->GetNonObsoleteMethod(), frame.method_->GetNonObsoleteMethod())
            << "Expected " << ArtMethod::PrettyMethod(m)
            << ", Found " << ArtMethod::PrettyMethod(frame.method_);
        return_pc = frame.return_pc_;
        if (kVerboseInstrumentation) {
          LOG(INFO) << "Ignoring already instrumented " << frame.Dump();
        }
      } else {
        // If it is a JITed frame then just set the deopt bit if required
        // otherwise continue
        const OatQuickMethodHeader* method_header = GetCurrentOatQuickMethodHeader();
        if (method_header != nullptr && method_header->HasShouldDeoptimizeFlag()) {
          if (deopt_all_frames_) {
            SetShouldDeoptimizeFlag(DeoptimizeFlagValue::kDebug);
          }
          return true;
        }
        CHECK_NE(return_pc, 0U);
        if (UNLIKELY(reached_existing_instrumentation_frames_ && !m->IsRuntimeMethod())) {
          // We already saw an existing instrumentation frame so this should be a runtime-method
          // inserted by the interpreter or runtime.
          std::string thread_name;
          GetThread()->GetThreadName(thread_name);
          LOG(FATAL) << "While walking " << thread_name << " found unexpected non-runtime method"
                     << " without instrumentation exit return or interpreter frame."
                     << " method is " << GetMethod()->PrettyMethod()
                     << " return_pc is " << std::hex << return_pc;
          UNREACHABLE();
        }
        if (m->IsRuntimeMethod()) {
          size_t frame_size = GetCurrentQuickFrameInfo().FrameSizeInBytes();
          ArtMethod** caller_frame = reinterpret_cast<ArtMethod**>(
              reinterpret_cast<uint8_t*>(GetCurrentQuickFrame()) + frame_size);
          if (*caller_frame != nullptr && (*caller_frame)->IsNative()) {
            // Do not install instrumentation exit on return to JNI stubs.
            return true;
          }
        }
        InstrumentationStackFrame instrumentation_frame(
            m->IsRuntimeMethod() ? nullptr : GetThisObject().Ptr(),
            m,
            return_pc,
            GetFrameId(),    // A runtime method still gets a frame id.
            false,
            force_deopt_id_);
        if (kVerboseInstrumentation) {
          LOG(INFO) << "Pushing frame " << instrumentation_frame.Dump();
        }

        instrumentation_stack_->insert({GetReturnPcAddr(), instrumentation_frame});
        SetReturnPc(instrumentation_exit_pc_);
      }
      return true;  // Continue.
    }
    std::map<uintptr_t, InstrumentationStackFrame>* const instrumentation_stack_;
    std::vector<InstrumentationStackFrame> shadow_stack_;
    const uintptr_t instrumentation_exit_pc_;
    bool reached_existing_instrumentation_frames_;
    uint64_t force_deopt_id_;
    bool deopt_all_frames_;
  };
  if (kVerboseInstrumentation) {
    std::string thread_name;
    thread->GetThreadName(thread_name);
    LOG(INFO) << "Installing exit stubs in " << thread_name;
  }

  Instrumentation* instrumentation = reinterpret_cast<Instrumentation*>(arg);
  std::unique_ptr<Context> context(Context::Create());
  uintptr_t instrumentation_exit_pc = reinterpret_cast<uintptr_t>(GetQuickInstrumentationExitPc());
  InstallStackVisitor visitor(thread,
                              context.get(),
                              instrumentation_exit_pc,
                              instrumentation->current_force_deopt_id_,
                              deopt_all_frames);
  visitor.WalkStack(true);

  if (instrumentation->ShouldNotifyMethodEnterExitEvents()) {
    // Create method enter events for all methods currently on the thread's stack. We only do this
    // if no debugger is attached to prevent from posting events twice.
    // TODO: This is the only place we make use of frame_id_. We should create a
    // std::vector instead and populate it as we walk the stack.
    auto ssi = visitor.shadow_stack_.rbegin();
    for (auto isi = thread->GetInstrumentationStack()->rbegin(),
        end = thread->GetInstrumentationStack()->rend(); isi != end; ++isi) {
      while (ssi != visitor.shadow_stack_.rend() && (*ssi).frame_id_ < isi->second.frame_id_) {
        instrumentation->MethodEnterEvent(thread, (*ssi).method_);
        ++ssi;
      }
      if (!isi->second.interpreter_entry_ && !isi->second.method_->IsRuntimeMethod()) {
        instrumentation->MethodEnterEvent(thread, isi->second.method_);
      }
    }
  }
  thread->VerifyStack();
}

void Instrumentation::InstrumentThreadStack(Thread* thread, bool force_deopt) {
  instrumentation_stubs_installed_ = true;
  InstrumentationInstallStack(thread, this, force_deopt);
}

// Removes the instrumentation exit pc as the return PC for every quick frame.
static void InstrumentationRestoreStack(Thread* thread, void* arg)
    REQUIRES(Locks::mutator_lock_) {
  Locks::mutator_lock_->AssertExclusiveHeld(Thread::Current());

  struct RestoreStackVisitor final : public StackVisitor {
    RestoreStackVisitor(Thread* thread_in, uintptr_t instrumentation_exit_pc,
                        Instrumentation* instrumentation)
        : StackVisitor(thread_in, nullptr, kInstrumentationStackWalk),
          thread_(thread_in),
          instrumentation_exit_pc_(instrumentation_exit_pc),
          instrumentation_(instrumentation),
          instrumentation_stack_(thread_in->GetInstrumentationStack()),
          frames_removed_(0) {}

    bool VisitFrame() override REQUIRES_SHARED(Locks::mutator_lock_) {
      if (instrumentation_stack_->size() == 0) {
        return false;  // Stop.
      }
      ArtMethod* m = GetMethod();
      if (GetCurrentQuickFrame() == nullptr) {
        if (kVerboseInstrumentation) {
          LOG(INFO) << "  Ignoring a shadow frame. Frame " << GetFrameId()
              << " Method=" << ArtMethod::PrettyMethod(m);
        }
        return true;  // Ignore shadow frames.
      }
      if (m == nullptr) {
        if (kVerboseInstrumentation) {
          LOG(INFO) << "  Skipping upcall. Frame " << GetFrameId();
        }
        return true;  // Ignore upcalls.
      }
      auto it = instrumentation_stack_->find(GetReturnPcAddr());
      if (it != instrumentation_stack_->end()) {
        const InstrumentationStackFrame& instrumentation_frame = it->second;
        if (kVerboseInstrumentation) {
          LOG(INFO) << "  Removing exit stub in " << DescribeLocation();
        }
        if (instrumentation_frame.interpreter_entry_) {
          CHECK(m == Runtime::Current()->GetCalleeSaveMethod(CalleeSaveType::kSaveRefsAndArgs));
        } else {
          CHECK_EQ(m->GetNonObsoleteMethod(),
                   instrumentation_frame.method_->GetNonObsoleteMethod())
              << ArtMethod::PrettyMethod(m)
              << " and " << instrumentation_frame.method_->GetNonObsoleteMethod()->PrettyMethod();
        }
        SetReturnPc(instrumentation_frame.return_pc_);
        if (instrumentation_->ShouldNotifyMethodEnterExitEvents() &&
            !m->IsRuntimeMethod()) {
          // Create the method exit events. As the methods didn't really exit the result is 0.
          // We only do this if no debugger is attached to prevent from posting events twice.
          JValue val;
          instrumentation_->MethodExitEvent(thread_, m, OptionalFrame{}, val);
        }
        frames_removed_++;
      } else {
        if (kVerboseInstrumentation) {
          LOG(INFO) << "  No exit stub in " << DescribeLocation();
        }
      }
      return true;  // Continue.
    }
    Thread* const thread_;
    const uintptr_t instrumentation_exit_pc_;
    Instrumentation* const instrumentation_;
    std::map<uintptr_t, instrumentation::InstrumentationStackFrame>* const instrumentation_stack_;
    size_t frames_removed_;
  };
  if (kVerboseInstrumentation) {
    std::string thread_name;
    thread->GetThreadName(thread_name);
    LOG(INFO) << "Removing exit stubs in " << thread_name;
  }
  std::map<uintptr_t, instrumentation::InstrumentationStackFrame>* stack =
      thread->GetInstrumentationStack();
  if (stack->size() > 0) {
    Instrumentation* instrumentation = reinterpret_cast<Instrumentation*>(arg);
    uintptr_t instrumentation_exit_pc =
        reinterpret_cast<uintptr_t>(GetQuickInstrumentationExitPc());
    RestoreStackVisitor visitor(thread, instrumentation_exit_pc, instrumentation);
    visitor.WalkStack(true);
    CHECK_EQ(visitor.frames_removed_, stack->size());
    stack->clear();
  }
}

void Instrumentation::DeoptimizeAllThreadFrames() {
  Thread* self = Thread::Current();
  MutexLock mu(self, *Locks::thread_list_lock_);
  ThreadList* tl = Runtime::Current()->GetThreadList();
  tl->ForEach([&](Thread* t) {
    Locks::mutator_lock_->AssertExclusiveHeld(self);
    InstrumentThreadStack(t, /* deopt_all_frames= */ true);
  });
  current_force_deopt_id_++;
}

static bool HasEvent(Instrumentation::InstrumentationEvent expected, uint32_t events) {
  return (events & expected) != 0;
}

static void PotentiallyAddListenerTo(Instrumentation::InstrumentationEvent event,
                                     uint32_t events,
                                     std::list<InstrumentationListener*>& list,
                                     InstrumentationListener* listener,
                                     bool* has_listener)
    REQUIRES(Locks::mutator_lock_, !Locks::thread_list_lock_, !Locks::classlinker_classes_lock_) {
  Locks::mutator_lock_->AssertExclusiveHeld(Thread::Current());
  if (!HasEvent(event, events)) {
    return;
  }
  // If there is a free slot in the list, we insert the listener in that slot.
  // Otherwise we add it to the end of the list.
  auto it = std::find(list.begin(), list.end(), nullptr);
  if (it != list.end()) {
    *it = listener;
  } else {
    list.push_back(listener);
  }
  *has_listener = true;
}

void Instrumentation::AddListener(InstrumentationListener* listener, uint32_t events) {
  Locks::mutator_lock_->AssertExclusiveHeld(Thread::Current());
  PotentiallyAddListenerTo(kMethodEntered,
                           events,
                           method_entry_listeners_,
                           listener,
                           &have_method_entry_listeners_);
  PotentiallyAddListenerTo(kMethodExited,
                           events,
                           method_exit_listeners_,
                           listener,
                           &have_method_exit_listeners_);
  PotentiallyAddListenerTo(kMethodUnwind,
                           events,
                           method_unwind_listeners_,
                           listener,
                           &have_method_unwind_listeners_);
  PotentiallyAddListenerTo(kBranch,
                           events,
                           branch_listeners_,
                           listener,
                           &have_branch_listeners_);
  PotentiallyAddListenerTo(kDexPcMoved,
                           events,
                           dex_pc_listeners_,
                           listener,
                           &have_dex_pc_listeners_);
  PotentiallyAddListenerTo(kFieldRead,
                           events,
                           field_read_listeners_,
                           listener,
                           &have_field_read_listeners_);
  PotentiallyAddListenerTo(kFieldWritten,
                           events,
                           field_write_listeners_,
                           listener,
                           &have_field_write_listeners_);
  PotentiallyAddListenerTo(kExceptionThrown,
                           events,
                           exception_thrown_listeners_,
                           listener,
                           &have_exception_thrown_listeners_);
  PotentiallyAddListenerTo(kWatchedFramePop,
                           events,
                           watched_frame_pop_listeners_,
                           listener,
                           &have_watched_frame_pop_listeners_);
  PotentiallyAddListenerTo(kExceptionHandled,
                           events,
                           exception_handled_listeners_,
                           listener,
                           &have_exception_handled_listeners_);
}

static void PotentiallyRemoveListenerFrom(Instrumentation::InstrumentationEvent event,
                                          uint32_t events,
                                          std::list<InstrumentationListener*>& list,
                                          InstrumentationListener* listener,
                                          bool* has_listener)
    REQUIRES(Locks::mutator_lock_, !Locks::thread_list_lock_, !Locks::classlinker_classes_lock_) {
  Locks::mutator_lock_->AssertExclusiveHeld(Thread::Current());
  if (!HasEvent(event, events)) {
    return;
  }
  auto it = std::find(list.begin(), list.end(), listener);
  if (it != list.end()) {
    // Just update the entry, do not remove from the list. Removing entries in the list
    // is unsafe when mutators are iterating over it.
    *it = nullptr;
  }

  // Check if the list contains any non-null listener, and update 'has_listener'.
  for (InstrumentationListener* l : list) {
    if (l != nullptr) {
      *has_listener = true;
      return;
    }
  }
  *has_listener = false;
}

void Instrumentation::RemoveListener(InstrumentationListener* listener, uint32_t events) {
  Locks::mutator_lock_->AssertExclusiveHeld(Thread::Current());
  PotentiallyRemoveListenerFrom(kMethodEntered,
                                events,
                                method_entry_listeners_,
                                listener,
                                &have_method_entry_listeners_);
  PotentiallyRemoveListenerFrom(kMethodExited,
                                events,
                                method_exit_listeners_,
                                listener,
                                &have_method_exit_listeners_);
  PotentiallyRemoveListenerFrom(kMethodUnwind,
                                events,
                                method_unwind_listeners_,
                                listener,
                                &have_method_unwind_listeners_);
  PotentiallyRemoveListenerFrom(kBranch,
                                events,
                                branch_listeners_,
                                listener,
                                &have_branch_listeners_);
  PotentiallyRemoveListenerFrom(kDexPcMoved,
                                events,
                                dex_pc_listeners_,
                                listener,
                                &have_dex_pc_listeners_);
  PotentiallyRemoveListenerFrom(kFieldRead,
                                events,
                                field_read_listeners_,
                                listener,
                                &have_field_read_listeners_);
  PotentiallyRemoveListenerFrom(kFieldWritten,
                                events,
                                field_write_listeners_,
                                listener,
                                &have_field_write_listeners_);
  PotentiallyRemoveListenerFrom(kExceptionThrown,
                                events,
                                exception_thrown_listeners_,
                                listener,
                                &have_exception_thrown_listeners_);
  PotentiallyRemoveListenerFrom(kWatchedFramePop,
                                events,
                                watched_frame_pop_listeners_,
                                listener,
                                &have_watched_frame_pop_listeners_);
  PotentiallyRemoveListenerFrom(kExceptionHandled,
                                events,
                                exception_handled_listeners_,
                                listener,
                                &have_exception_handled_listeners_);
}

Instrumentation::InstrumentationLevel Instrumentation::GetCurrentInstrumentationLevel() const {
  return instrumentation_level_;
}

bool Instrumentation::RequiresInstrumentationInstallation(InstrumentationLevel new_level) const {
  // We need to reinstall instrumentation if we go to a different level.
  return GetCurrentInstrumentationLevel() != new_level;
}

void Instrumentation::ConfigureStubs(const char* key, InstrumentationLevel desired_level) {
  // Store the instrumentation level for this key or remove it.
  if (desired_level == InstrumentationLevel::kInstrumentNothing) {
    // The client no longer needs instrumentation.
    requested_instrumentation_levels_.erase(key);
  } else {
    // The client needs instrumentation.
    requested_instrumentation_levels_.Overwrite(key, desired_level);
  }

  UpdateStubs();
}

void Instrumentation::EnableSingleThreadDeopt(const char* key) {
  // Prepare for single thread deopt by installing instrumentation stubs.
  ConfigureStubs(key, InstrumentationLevel::kInstrumentWithInstrumentationStubs);
}

void Instrumentation::UpdateInstrumentationLevel(InstrumentationLevel requested_level) {
  instrumentation_level_ = requested_level;
}

void Instrumentation::UpdateStubs() {
  // Look for the highest required instrumentation level.
  InstrumentationLevel requested_level = InstrumentationLevel::kInstrumentNothing;
  for (const auto& v : requested_instrumentation_levels_) {
    requested_level = std::max(requested_level, v.second);
  }

  if (!RequiresInstrumentationInstallation(requested_level)) {
    // We're already set.
    return;
  }
  Thread* const self = Thread::Current();
  Runtime* runtime = Runtime::Current();
  Locks::mutator_lock_->AssertExclusiveHeld(self);
  Locks::thread_list_lock_->AssertNotHeld(self);
  UpdateInstrumentationLevel(requested_level);
  if (requested_level > InstrumentationLevel::kInstrumentNothing) {
    InstallStubsClassVisitor visitor(this);
    runtime->GetClassLinker()->VisitClasses(&visitor);
    instrumentation_stubs_installed_ = true;
    MutexLock mu(self, *Locks::thread_list_lock_);
    for (Thread* thread : Runtime::Current()->GetThreadList()->GetList()) {
      InstrumentThreadStack(thread, /* deopt_all_frames= */ false);
    }
  } else {
    InstallStubsClassVisitor visitor(this);
    runtime->GetClassLinker()->VisitClasses(&visitor);
    // Restore stack only if there is no method currently deoptimized.
    bool empty = IsDeoptimizedMethodsEmpty();
    if (empty) {
      MutexLock mu(self, *Locks::thread_list_lock_);
      bool no_remaining_deopts = true;
      // Check that there are no other forced deoptimizations. Do it here so we only need to lock
      // thread_list_lock once.
      // The compiler gets confused on the thread annotations, so use
      // NO_THREAD_SAFETY_ANALYSIS. Note that we hold the mutator lock
      // exclusively at this point.
      Locks::mutator_lock_->AssertExclusiveHeld(self);
      runtime->GetThreadList()->ForEach([&](Thread* t) NO_THREAD_SAFETY_ANALYSIS {
        no_remaining_deopts =
            no_remaining_deopts && !t->IsForceInterpreter() &&
            std::all_of(t->GetInstrumentationStack()->cbegin(),
                        t->GetInstrumentationStack()->cend(),
                        [&](const auto& frame) REQUIRES_SHARED(Locks::mutator_lock_) {
                          return frame.second.force_deopt_id_ == current_force_deopt_id_;
                        });
      });
      if (no_remaining_deopts) {
        Runtime::Current()->GetThreadList()->ForEach(InstrumentationRestoreStack, this);
        // Only do this after restoring, as walking the stack when restoring will see
        // the instrumentation exit pc.
        instrumentation_stubs_installed_ = false;
      }
    }
  }
}

static void ResetQuickAllocEntryPointsForThread(Thread* thread, void* arg ATTRIBUTE_UNUSED) {
  thread->ResetQuickAllocEntryPointsForThread();
}

void Instrumentation::SetEntrypointsInstrumented(bool instrumented) {
  Thread* self = Thread::Current();
  Runtime* runtime = Runtime::Current();
  Locks::mutator_lock_->AssertNotHeld(self);
  Locks::instrument_entrypoints_lock_->AssertHeld(self);
  if (runtime->IsStarted()) {
    ScopedSuspendAll ssa(__FUNCTION__);
    MutexLock mu(self, *Locks::runtime_shutdown_lock_);
    SetQuickAllocEntryPointsInstrumented(instrumented);
    ResetQuickAllocEntryPoints();
    alloc_entrypoints_instrumented_ = instrumented;
  } else {
    MutexLock mu(self, *Locks::runtime_shutdown_lock_);
    SetQuickAllocEntryPointsInstrumented(instrumented);

    // Note: ResetQuickAllocEntryPoints only works when the runtime is started. Manually run the
    //       update for just this thread.
    // Note: self may be null. One of those paths is setting instrumentation in the Heap
    //       constructor for gcstress mode.
    if (self != nullptr) {
      ResetQuickAllocEntryPointsForThread(self, nullptr);
    }

    alloc_entrypoints_instrumented_ = instrumented;
  }
}

void Instrumentation::InstrumentQuickAllocEntryPoints() {
  MutexLock mu(Thread::Current(), *Locks::instrument_entrypoints_lock_);
  InstrumentQuickAllocEntryPointsLocked();
}

void Instrumentation::UninstrumentQuickAllocEntryPoints() {
  MutexLock mu(Thread::Current(), *Locks::instrument_entrypoints_lock_);
  UninstrumentQuickAllocEntryPointsLocked();
}

void Instrumentation::InstrumentQuickAllocEntryPointsLocked() {
  Locks::instrument_entrypoints_lock_->AssertHeld(Thread::Current());
  if (quick_alloc_entry_points_instrumentation_counter_ == 0) {
    SetEntrypointsInstrumented(true);
  }
  ++quick_alloc_entry_points_instrumentation_counter_;
}

void Instrumentation::UninstrumentQuickAllocEntryPointsLocked() {
  Locks::instrument_entrypoints_lock_->AssertHeld(Thread::Current());
  CHECK_GT(quick_alloc_entry_points_instrumentation_counter_, 0U);
  --quick_alloc_entry_points_instrumentation_counter_;
  if (quick_alloc_entry_points_instrumentation_counter_ == 0) {
    SetEntrypointsInstrumented(false);
  }
}

void Instrumentation::ResetQuickAllocEntryPoints() {
  Runtime* runtime = Runtime::Current();
  if (runtime->IsStarted()) {
    MutexLock mu(Thread::Current(), *Locks::thread_list_lock_);
    runtime->GetThreadList()->ForEach(ResetQuickAllocEntryPointsForThread, nullptr);
  }
}

std::string Instrumentation::EntryPointString(const void* code) {
  ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
  jit::Jit* jit = Runtime::Current()->GetJit();
  if (class_linker->IsQuickToInterpreterBridge(code)) {
    return "interpreter";
  } else if (class_linker->IsQuickResolutionStub(code)) {
    return "resolution";
  } else if (code == GetQuickInstrumentationEntryPoint()) {
    return "instrumentation";
  } else if (jit != nullptr && jit->GetCodeCache()->ContainsPc(code)) {
    return "jit";
  } else if (code == GetInvokeObsoleteMethodStub()) {
    return "obsolete";
  } else if (code == interpreter::GetNterpEntryPoint()) {
    return "nterp";
  } else if (class_linker->IsQuickGenericJniStub(code)) {
    return "generic jni";
  } else if (Runtime::Current()->GetOatFileManager().ContainsPc(code)) {
    return "oat";
  }
  return "unknown";
}

void Instrumentation::UpdateMethodsCodeImpl(ArtMethod* method, const void* new_code) {
  if (!EntryExitStubsInstalled()) {
    // Fast path: no instrumentation.
    DCHECK(!IsDeoptimized(method));
    UpdateEntryPoints(method, new_code);
    return;
  }

  ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
  if (class_linker->IsQuickToInterpreterBridge(new_code)) {
    // It's always OK to update to the interpreter.
    UpdateEntryPoints(method, new_code);
    return;
  }

  if (IsDeoptimized(method)) {
    DCHECK(class_linker->IsQuickToInterpreterBridge(method->GetEntryPointFromQuickCompiledCode()))
        << EntryPointString(method->GetEntryPointFromQuickCompiledCode());
    // Don't update, stay deoptimized.
    return;
  }

  if (CodeNeedsEntryExitStub(new_code, method)) {
    DCHECK(method->GetEntryPointFromQuickCompiledCode() == GetQuickInstrumentationEntryPoint() ||
        class_linker->IsQuickToInterpreterBridge(method->GetEntryPointFromQuickCompiledCode()))
              << EntryPointString(method->GetEntryPointFromQuickCompiledCode());
    // If the code we want to update the method with still needs entry/exit stub, just skip.
    return;
  }

  // At this point, we can update as asked.
  UpdateEntryPoints(method, new_code);
}

void Instrumentation::UpdateNativeMethodsCodeToJitCode(ArtMethod* method, const void* new_code) {
  // We don't do any read barrier on `method`'s declaring class in this code, as the JIT might
  // enter here on a soon-to-be deleted ArtMethod. Updating the entrypoint is OK though, as
  // the ArtMethod is still in memory.
  if (EntryExitStubsInstalled()) {
    // If stubs are installed don't update.
    return;
  }
  UpdateEntryPoints(method, new_code);
}

void Instrumentation::UpdateMethodsCode(ArtMethod* method, const void* new_code) {
  DCHECK(method->GetDeclaringClass()->IsResolved());
  UpdateMethodsCodeImpl(method, new_code);
}

bool Instrumentation::AddDeoptimizedMethod(ArtMethod* method) {
  if (IsDeoptimizedMethod(method)) {
    // Already in the map. Return.
    return false;
  }
  // Not found. Add it.
  deoptimized_methods_.insert(method);
  return true;
}

bool Instrumentation::IsDeoptimizedMethod(ArtMethod* method) {
  return deoptimized_methods_.find(method) != deoptimized_methods_.end();
}

ArtMethod* Instrumentation::BeginDeoptimizedMethod() {
  if (deoptimized_methods_.empty()) {
    // Empty.
    return nullptr;
  }
  return *deoptimized_methods_.begin();
}

bool Instrumentation::RemoveDeoptimizedMethod(ArtMethod* method) {
  auto it = deoptimized_methods_.find(method);
  if (it == deoptimized_methods_.end()) {
    return false;
  }
  deoptimized_methods_.erase(it);
  return true;
}

bool Instrumentation::IsDeoptimizedMethodsEmptyLocked() const {
  return deoptimized_methods_.empty();
}

void Instrumentation::Deoptimize(ArtMethod* method) {
  CHECK(!method->IsNative());
  CHECK(!method->IsProxyMethod());
  CHECK(method->IsInvokable());

  Thread* self = Thread::Current();
  {
    WriterMutexLock mu(self, *GetDeoptimizedMethodsLock());
    bool has_not_been_deoptimized = AddDeoptimizedMethod(method);
    CHECK(has_not_been_deoptimized) << "Method " << ArtMethod::PrettyMethod(method)
        << " is already deoptimized";
  }
  if (!InterpreterStubsInstalled()) {
    UpdateEntryPoints(method, GetQuickToInterpreterBridge());

    // Install instrumentation exit stub and instrumentation frames. We may already have installed
    // these previously so it will only cover the newly created frames.
    instrumentation_stubs_installed_ = true;
    MutexLock mu(self, *Locks::thread_list_lock_);
    for (Thread* thread : Runtime::Current()->GetThreadList()->GetList()) {
      // This isn't a strong deopt. We deopt this method if it is still in the
      // deopt methods list. If by the time we hit this frame we no longer need
      // a deopt it is safe to continue. So we don't mark the frame.
      InstrumentThreadStack(thread, /* deopt_all_frames= */ false);
    }
  }
}

void Instrumentation::Undeoptimize(ArtMethod* method) {
  CHECK(!method->IsNative());
  CHECK(!method->IsProxyMethod());
  CHECK(method->IsInvokable());

  Thread* self = Thread::Current();
  bool empty;
  {
    WriterMutexLock mu(self, *GetDeoptimizedMethodsLock());
    bool found_and_erased = RemoveDeoptimizedMethod(method);
    CHECK(found_and_erased) << "Method " << ArtMethod::PrettyMethod(method)
        << " is not deoptimized";
    empty = IsDeoptimizedMethodsEmptyLocked();
  }

  // Restore code and possibly stack only if we did not deoptimize everything.
  if (!InterpreterStubsInstalled()) {
    // Restore its code or resolution trampoline.
    if (InterpretOnly(method)) {
      UpdateEntryPoints(method, GetQuickToInterpreterBridge());
    } else if (NeedsClinitCheckBeforeCall(method) &&
               !method->GetDeclaringClass()->IsVisiblyInitialized()) {
      UpdateEntryPoints(method, GetQuickResolutionStub());
    } else {
      UpdateEntryPoints(method, GetOptimizedCodeFor(method));
    }

    // If there is no deoptimized method left, we can restore the stack of each thread.
    if (empty && !EntryExitStubsInstalled()) {
      MutexLock mu(self, *Locks::thread_list_lock_);
      Runtime::Current()->GetThreadList()->ForEach(InstrumentationRestoreStack, this);
      instrumentation_stubs_installed_ = false;
    }
  }
}

bool Instrumentation::IsDeoptimizedMethodsEmpty() const {
  ReaderMutexLock mu(Thread::Current(), *GetDeoptimizedMethodsLock());
  return deoptimized_methods_.empty();
}

bool Instrumentation::IsDeoptimized(ArtMethod* method) {
  DCHECK(method != nullptr);
  ReaderMutexLock mu(Thread::Current(), *GetDeoptimizedMethodsLock());
  return IsDeoptimizedMethod(method);
}


void Instrumentation::DisableDeoptimization(const char* key) {
  // Remove any instrumentation support added for deoptimization.
  ConfigureStubs(key, InstrumentationLevel::kInstrumentNothing);
  // Undeoptimized selected methods.
  while (true) {
    ArtMethod* method;
    {
      ReaderMutexLock mu(Thread::Current(), *GetDeoptimizedMethodsLock());
      if (IsDeoptimizedMethodsEmptyLocked()) {
        break;
      }
      method = BeginDeoptimizedMethod();
      CHECK(method != nullptr);
    }
    Undeoptimize(method);
  }
}

// Indicates if instrumentation should notify method enter/exit events to the listeners.
bool Instrumentation::ShouldNotifyMethodEnterExitEvents() const {
  if (!HasMethodEntryListeners() && !HasMethodExitListeners()) {
    return false;
  }
  return !InterpreterStubsInstalled();
}

void Instrumentation::DeoptimizeEverything(const char* key) {
  ConfigureStubs(key, InstrumentationLevel::kInstrumentWithInterpreter);
}

void Instrumentation::UndeoptimizeEverything(const char* key) {
  CHECK(InterpreterStubsInstalled());
  ConfigureStubs(key, InstrumentationLevel::kInstrumentNothing);
}

void Instrumentation::EnableMethodTracing(const char* key, bool needs_interpreter) {
  InstrumentationLevel level;
  if (needs_interpreter) {
    level = InstrumentationLevel::kInstrumentWithInterpreter;
  } else {
    level = InstrumentationLevel::kInstrumentWithInstrumentationStubs;
  }
  ConfigureStubs(key, level);
}

void Instrumentation::DisableMethodTracing(const char* key) {
  ConfigureStubs(key, InstrumentationLevel::kInstrumentNothing);
}

const void* Instrumentation::GetCodeForInvoke(ArtMethod* method) {
  // This is called by instrumentation and resolution trampolines
  // and that should never be getting proxy methods.
  DCHECK(!method->IsProxyMethod()) << method->PrettyMethod();
  ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
  const void* code = method->GetEntryPointFromQuickCompiledCodePtrSize(kRuntimePointerSize);
  // If we don't have the instrumentation, the resolution stub, or the
  // interpreter as entrypoint, just return the current entrypoint, assuming
  // it's the most optimized.
  if (code != GetQuickInstrumentationEntryPoint() &&
      !class_linker->IsQuickResolutionStub(code) &&
      !class_linker->IsQuickToInterpreterBridge(code)) {
    return code;
  }

  if (InterpretOnly(method)) {
    // If we're forced into interpreter just use it.
    return GetQuickToInterpreterBridge();
  }

  return GetOptimizedCodeFor(method);
}

void Instrumentation::MethodEnterEventImpl(Thread* thread, ArtMethod* method) const {
  DCHECK(!method->IsRuntimeMethod());
  if (HasMethodEntryListeners()) {
    for (InstrumentationListener* listener : method_entry_listeners_) {
      if (listener != nullptr) {
        listener->MethodEntered(thread, method);
      }
    }
  }
}

template <>
void Instrumentation::MethodExitEventImpl(Thread* thread,
                                          ArtMethod* method,
                                          OptionalFrame frame,
                                          MutableHandle<mirror::Object>& return_value) const {
  if (HasMethodExitListeners()) {
    for (InstrumentationListener* listener : method_exit_listeners_) {
      if (listener != nullptr) {
        listener->MethodExited(thread, method, frame, return_value);
      }
    }
  }
}

template<> void Instrumentation::MethodExitEventImpl(Thread* thread,
                                                     ArtMethod* method,
                                                     OptionalFrame frame,
                                                     JValue& return_value) const {
  if (HasMethodExitListeners()) {
    Thread* self = Thread::Current();
    StackHandleScope<1> hs(self);
    if (method->GetInterfaceMethodIfProxy(kRuntimePointerSize)->GetReturnTypePrimitive() !=
        Primitive::kPrimNot) {
      for (InstrumentationListener* listener : method_exit_listeners_) {
        if (listener != nullptr) {
          listener->MethodExited(thread, method, frame, return_value);
        }
      }
    } else {
      MutableHandle<mirror::Object> ret(hs.NewHandle(return_value.GetL()));
      MethodExitEventImpl(thread, method, frame, ret);
      return_value.SetL(ret.Get());
    }
  }
}

void Instrumentation::MethodUnwindEvent(Thread* thread,
                                        ObjPtr<mirror::Object> this_object,
                                        ArtMethod* method,
                                        uint32_t dex_pc) const {
  if (HasMethodUnwindListeners()) {
    Thread* self = Thread::Current();
    StackHandleScope<1> hs(self);
    Handle<mirror::Object> thiz(hs.NewHandle(this_object));
    for (InstrumentationListener* listener : method_unwind_listeners_) {
      if (listener != nullptr) {
        listener->MethodUnwind(thread, thiz, method, dex_pc);
      }
    }
  }
}

void Instrumentation::DexPcMovedEventImpl(Thread* thread,
                                          ObjPtr<mirror::Object> this_object,
                                          ArtMethod* method,
                                          uint32_t dex_pc) const {
  Thread* self = Thread::Current();
  StackHandleScope<1> hs(self);
  Handle<mirror::Object> thiz(hs.NewHandle(this_object));
  for (InstrumentationListener* listener : dex_pc_listeners_) {
    if (listener != nullptr) {
      listener->DexPcMoved(thread, thiz, method, dex_pc);
    }
  }
}

void Instrumentation::BranchImpl(Thread* thread,
                                 ArtMethod* method,
                                 uint32_t dex_pc,
                                 int32_t offset) const {
  for (InstrumentationListener* listener : branch_listeners_) {
    if (listener != nullptr) {
      listener->Branch(thread, method, dex_pc, offset);
    }
  }
}

void Instrumentation::WatchedFramePopImpl(Thread* thread, const ShadowFrame& frame) const {
  for (InstrumentationListener* listener : watched_frame_pop_listeners_) {
    if (listener != nullptr) {
      listener->WatchedFramePop(thread, frame);
    }
  }
}

void Instrumentation::FieldReadEventImpl(Thread* thread,
                                         ObjPtr<mirror::Object> this_object,
                                         ArtMethod* method,
                                         uint32_t dex_pc,
                                         ArtField* field) const {
  Thread* self = Thread::Current();
  StackHandleScope<1> hs(self);
  Handle<mirror::Object> thiz(hs.NewHandle(this_object));
  for (InstrumentationListener* listener : field_read_listeners_) {
    if (listener != nullptr) {
      listener->FieldRead(thread, thiz, method, dex_pc, field);
    }
  }
}

void Instrumentation::FieldWriteEventImpl(Thread* thread,
                                          ObjPtr<mirror::Object> this_object,
                                          ArtMethod* method,
                                          uint32_t dex_pc,
                                          ArtField* field,
                                          const JValue& field_value) const {
  Thread* self = Thread::Current();
  StackHandleScope<2> hs(self);
  Handle<mirror::Object> thiz(hs.NewHandle(this_object));
  if (field->IsPrimitiveType()) {
    for (InstrumentationListener* listener : field_write_listeners_) {
      if (listener != nullptr) {
        listener->FieldWritten(thread, thiz, method, dex_pc, field, field_value);
      }
    }
  } else {
    Handle<mirror::Object> val(hs.NewHandle(field_value.GetL()));
    for (InstrumentationListener* listener : field_write_listeners_) {
      if (listener != nullptr) {
        listener->FieldWritten(thread, thiz, method, dex_pc, field, val);
      }
    }
  }
}

void Instrumentation::ExceptionThrownEvent(Thread* thread,
                                           ObjPtr<mirror::Throwable> exception_object) const {
  Thread* self = Thread::Current();
  StackHandleScope<1> hs(self);
  Handle<mirror::Throwable> h_exception(hs.NewHandle(exception_object));
  if (HasExceptionThrownListeners()) {
    DCHECK_EQ(thread->GetException(), h_exception.Get());
    thread->ClearException();
    for (InstrumentationListener* listener : exception_thrown_listeners_) {
      if (listener != nullptr) {
        listener->ExceptionThrown(thread, h_exception);
      }
    }
    // See b/65049545 for discussion about this behavior.
    thread->AssertNoPendingException();
    thread->SetException(h_exception.Get());
  }
}

void Instrumentation::ExceptionHandledEvent(Thread* thread,
                                            ObjPtr<mirror::Throwable> exception_object) const {
  Thread* self = Thread::Current();
  StackHandleScope<1> hs(self);
  Handle<mirror::Throwable> h_exception(hs.NewHandle(exception_object));
  if (HasExceptionHandledListeners()) {
    // We should have cleared the exception so that callers can detect a new one.
    DCHECK(thread->GetException() == nullptr);
    for (InstrumentationListener* listener : exception_handled_listeners_) {
      if (listener != nullptr) {
        listener->ExceptionHandled(thread, h_exception);
      }
    }
  }
}

void Instrumentation::PushInstrumentationStackFrame(Thread* self,
                                                    ObjPtr<mirror::Object> this_object,
                                                    ArtMethod* method,
                                                    uintptr_t stack_ptr,
                                                    uintptr_t lr,
                                                    bool interpreter_entry) {
  DCHECK(!self->IsExceptionPending());
  std::map<uintptr_t, instrumentation::InstrumentationStackFrame>* stack =
      self->GetInstrumentationStack();
  if (kVerboseInstrumentation) {
    LOG(INFO) << "Entering " << ArtMethod::PrettyMethod(method) << " from PC "
              << reinterpret_cast<void*>(lr);
  }

  // We send the enter event before pushing the instrumentation frame to make cleanup easier. If the
  // event causes an exception we can simply send the unwind event and return.
  StackHandleScope<1> hs(self);
  Handle<mirror::Object> h_this(hs.NewHandle(this_object));
  if (!interpreter_entry) {
    MethodEnterEvent(self, method);
    if (self->IsExceptionPending()) {
      MethodUnwindEvent(self, h_this.Get(), method, 0);
      return;
    }
  }

  // We have a callee-save frame meaning this value is guaranteed to never be 0.
  DCHECK(!self->IsExceptionPending());
  size_t frame_id = StackVisitor::ComputeNumFrames(self, kInstrumentationStackWalk);

  instrumentation::InstrumentationStackFrame instrumentation_frame(
      h_this.Get(), method, lr, frame_id, interpreter_entry, current_force_deopt_id_);
  stack->insert({stack_ptr, instrumentation_frame});
}

DeoptimizationMethodType Instrumentation::GetDeoptimizationMethodType(ArtMethod* method) {
  if (method->IsRuntimeMethod()) {
    // Certain methods have strict requirement on whether the dex instruction
    // should be re-executed upon deoptimization.
    if (method == Runtime::Current()->GetCalleeSaveMethod(
        CalleeSaveType::kSaveEverythingForClinit)) {
      return DeoptimizationMethodType::kKeepDexPc;
    }
    if (method == Runtime::Current()->GetCalleeSaveMethod(
        CalleeSaveType::kSaveEverythingForSuspendCheck)) {
      return DeoptimizationMethodType::kKeepDexPc;
    }
  }
  return DeoptimizationMethodType::kDefault;
}

// Try to get the shorty of a runtime method if it's an invocation stub.
static char GetRuntimeMethodShorty(Thread* thread) REQUIRES_SHARED(Locks::mutator_lock_) {
  char shorty = 'V';
  StackVisitor::WalkStack(
      [&shorty](const art::StackVisitor* stack_visitor) REQUIRES_SHARED(Locks::mutator_lock_) {
        ArtMethod* m = stack_visitor->GetMethod();
        if (m == nullptr || m->IsRuntimeMethod()) {
          return true;
        }
        // The first Java method.
        if (m->IsNative()) {
          // Use JNI method's shorty for the jni stub.
          shorty = m->GetShorty()[0];
        } else if (m->IsProxyMethod()) {
          // Proxy method just invokes its proxied method via
          // art_quick_proxy_invoke_handler.
          shorty = m->GetInterfaceMethodIfProxy(kRuntimePointerSize)->GetShorty()[0];
        } else {
          const Instruction& instr = m->DexInstructions().InstructionAt(stack_visitor->GetDexPc());
          if (instr.IsInvoke()) {
            uint16_t method_index = static_cast<uint16_t>(instr.VRegB());
            const DexFile* dex_file = m->GetDexFile();
            if (interpreter::IsStringInit(dex_file, method_index)) {
              // Invoking string init constructor is turned into invoking
              // StringFactory.newStringFromChars() which returns a string.
              shorty = 'L';
            } else {
              shorty = dex_file->GetMethodShorty(method_index)[0];
            }

          } else {
            // It could be that a non-invoke opcode invokes a stub, which in turn
            // invokes Java code. In such cases, we should never expect a return
            // value from the stub.
          }
        }
        // Stop stack walking since we've seen a Java frame.
        return false;
      },
      thread,
      /* context= */ nullptr,
      art::StackVisitor::StackWalkKind::kIncludeInlinedFrames);
  return shorty;
}

JValue Instrumentation::GetReturnValue(
    Thread* self, ArtMethod* method, bool* is_ref, uint64_t* gpr_result, uint64_t* fpr_result) {
  uint32_t length;
  const PointerSize pointer_size = Runtime::Current()->GetClassLinker()->GetImagePointerSize();
  char return_shorty;

  // Runtime method does not call into MethodExitEvent() so there should not be
  // suspension point below.
  ScopedAssertNoThreadSuspension ants(__FUNCTION__, method->IsRuntimeMethod());
  if (method->IsRuntimeMethod()) {
    Runtime* runtime = Runtime::Current();
    if (method != runtime->GetCalleeSaveMethod(CalleeSaveType::kSaveEverythingForClinit) &&
        method != runtime->GetCalleeSaveMethod(CalleeSaveType::kSaveEverythingForSuspendCheck)) {
      // If the caller is at an invocation point and the runtime method is not
      // for clinit, we need to pass return results to the caller.
      // We need the correct shorty to decide whether we need to pass the return
      // result for deoptimization below.
      return_shorty = GetRuntimeMethodShorty(self);
    } else {
      // Some runtime methods such as allocations, unresolved field getters, etc.
      // have return value. We don't need to set return_value since MethodExitEvent()
      // below isn't called for runtime methods. Deoptimization doesn't need the
      // value either since the dex instruction will be re-executed by the
      // interpreter, except these two cases:
      // (1) For an invoke, which is handled above to get the correct shorty.
      // (2) For MONITOR_ENTER/EXIT, which cannot be re-executed since it's not
      //     idempotent. However there is no return value for it anyway.
      return_shorty = 'V';
    }
  } else {
    return_shorty = method->GetInterfaceMethodIfProxy(pointer_size)->GetShorty(&length)[0];
  }

  *is_ref = return_shorty == '[' || return_shorty == 'L';
  JValue return_value;
  if (return_shorty == 'V') {
    return_value.SetJ(0);
  } else if (return_shorty == 'F' || return_shorty == 'D') {
    return_value.SetJ(*fpr_result);
  } else {
    return_value.SetJ(*gpr_result);
  }
  return return_value;
}

bool Instrumentation::ShouldDeoptimizeMethod(Thread* self, const NthCallerVisitor& visitor) {
  bool should_deoptimize_frame = false;
  const OatQuickMethodHeader* header = visitor.GetCurrentOatQuickMethodHeader();
  if (header != nullptr && header->HasShouldDeoptimizeFlag()) {
    uint8_t should_deopt_flag = visitor.GetShouldDeoptimizeFlag();
    // DeoptimizeFlag could be set for debugging or for CHA invalidations.
    // Deoptimize here only if it was requested for debugging. CHA
    // invalidations are handled in the JITed code.
    if ((should_deopt_flag & static_cast<uint8_t>(DeoptimizeFlagValue::kDebug)) != 0) {
      should_deoptimize_frame = true;
    }
  }
  return (visitor.caller != nullptr) &&
         (InterpreterStubsInstalled() || IsDeoptimized(visitor.caller) ||
          self->IsForceInterpreter() ||
          // NB Since structurally obsolete compiled methods might have the offsets of
          // methods/fields compiled in we need to go back to interpreter whenever we hit
          // them.
          visitor.caller->GetDeclaringClass()->IsObsoleteObject() ||
          Dbg::IsForcedInterpreterNeededForUpcall(self, visitor.caller) ||
          should_deoptimize_frame);
}

TwoWordReturn Instrumentation::PopInstrumentationStackFrame(Thread* self,
                                                            uintptr_t* return_pc_addr,
                                                            uint64_t* gpr_result,
                                                            uint64_t* fpr_result) {
  DCHECK(gpr_result != nullptr);
  DCHECK(fpr_result != nullptr);
  // Do the pop.
  std::map<uintptr_t, instrumentation::InstrumentationStackFrame>* stack =
      self->GetInstrumentationStack();
  CHECK_GT(stack->size(), 0U);
  auto it = stack->find(reinterpret_cast<uintptr_t>(return_pc_addr));
  CHECK(it != stack->end());
  InstrumentationStackFrame instrumentation_frame = it->second;
  stack->erase(it);

  // Set return PC and check the consistency of the stack.
  // We don't cache the return pc value in a local as it may change after
  // sending a method exit event.
  *return_pc_addr = instrumentation_frame.return_pc_;
  self->VerifyStack();

  ArtMethod* method = instrumentation_frame.method_;

  bool is_ref;
  JValue return_value = GetReturnValue(self, method, &is_ref, gpr_result, fpr_result);
  StackHandleScope<1> hs(self);
  MutableHandle<mirror::Object> res(hs.NewHandle<mirror::Object>(nullptr));
  if (is_ref) {
    // Take a handle to the return value so we won't lose it if we suspend.
    // FIXME: The `is_ref` is often guessed wrong, so even object aligment
    // assertion would fail for some tests. See b/204766614 .
    // DCHECK_ALIGNED(return_value.GetL(), kObjectAlignment);
    res.Assign(return_value.GetL());
  }
  if (!method->IsRuntimeMethod() && !instrumentation_frame.interpreter_entry_) {
    // Note that sending the event may change the contents of *return_pc_addr.
    MethodExitEvent(self, instrumentation_frame.method_, OptionalFrame{}, return_value);
  }

  // Deoptimize if the caller needs to continue execution in the interpreter. Do nothing if we get
  // back to an upcall.
  NthCallerVisitor visitor(self, 1, true);
  visitor.WalkStack(true);
  // Check if we forced all threads to deoptimize in the time between this frame being created and
  // now.
  bool should_deoptimize_frame = instrumentation_frame.force_deopt_id_ != current_force_deopt_id_;
  bool deoptimize = ShouldDeoptimizeMethod(self, visitor) || should_deoptimize_frame;

  if (is_ref) {
    // Restore the return value if it's a reference since it might have moved.
    *reinterpret_cast<mirror::Object**>(gpr_result) = res.Get();
  }
  if (deoptimize && Runtime::Current()->IsAsyncDeoptimizeable(*return_pc_addr)) {
    if (kVerboseInstrumentation) {
      LOG(INFO) << "Deoptimizing "
                << visitor.caller->PrettyMethod()
                << " by returning from "
                << method->PrettyMethod()
                << " with result "
                << std::hex << return_value.GetJ() << std::dec
                << " in "
                << *self;
    }
    DeoptimizationMethodType deopt_method_type = GetDeoptimizationMethodType(method);
    self->PushDeoptimizationContext(return_value,
                                    is_ref,
                                    /* exception= */ nullptr,
                                    /* from_code= */ false,
                                    deopt_method_type);
    return GetTwoWordSuccessValue(*return_pc_addr,
                                  reinterpret_cast<uintptr_t>(GetQuickDeoptimizationEntryPoint()));
  } else {
    if (deoptimize && !Runtime::Current()->IsAsyncDeoptimizeable(*return_pc_addr)) {
      VLOG(deopt) << "Got a deoptimization request on un-deoptimizable " << method->PrettyMethod()
                  << " at PC " << reinterpret_cast<void*>(*return_pc_addr);
    }
    if (kVerboseInstrumentation) {
      LOG(INFO) << "Returning from " << method->PrettyMethod()
                << " to PC " << reinterpret_cast<void*>(*return_pc_addr);
    }
    return GetTwoWordSuccessValue(0, *return_pc_addr);
  }
}

uintptr_t Instrumentation::PopFramesForDeoptimization(Thread* self, uintptr_t pop_until) const {
  std::map<uintptr_t, instrumentation::InstrumentationStackFrame>* stack =
      self->GetInstrumentationStack();
  // Pop all instrumentation frames below `pop_until`.
  uintptr_t return_pc = 0u;
  for (auto i = stack->begin(); i != stack->end() && i->first <= pop_until;) {
    auto e = i;
    ++i;
    if (kVerboseInstrumentation) {
      LOG(INFO) << "Popping for deoptimization " << e->second.method_->PrettyMethod();
    }
    return_pc = e->second.return_pc_;
    stack->erase(e);
  }
  return return_pc;
}

std::string InstrumentationStackFrame::Dump() const {
  std::ostringstream os;
  os << "Frame " << frame_id_ << " " << ArtMethod::PrettyMethod(method_) << ":"
      << reinterpret_cast<void*>(return_pc_) << " this=" << reinterpret_cast<void*>(this_object_)
      << " force_deopt_id=" << force_deopt_id_;
  return os.str();
}

}  // namespace instrumentation
}  // namespace art