path: root/runtime/jit/jit_code_cache.cc

/*
 * Copyright 2014 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 "jit_code_cache.h"

#include <sstream>

#include <android-base/logging.h>

#include "arch/context.h"
#include "art_method-inl.h"
#include "base/histogram-inl.h"
#include "base/logging.h"  // For VLOG.
#include "base/membarrier.h"
#include "base/memfd.h"
#include "base/mem_map.h"
#include "base/pointer_size.h"
#include "base/quasi_atomic.h"
#include "base/stl_util.h"
#include "base/systrace.h"
#include "base/time_utils.h"
#include "base/utils.h"
#include "cha.h"
#include "debugger_interface.h"
#include "dex/dex_file_loader.h"
#include "dex/method_reference.h"
#include "entrypoints/entrypoint_utils-inl.h"
#include "entrypoints/runtime_asm_entrypoints.h"
#include "gc/accounting/bitmap-inl.h"
#include "gc/allocator/art-dlmalloc.h"
#include "gc/scoped_gc_critical_section.h"
#include "handle.h"
#include "handle_scope-inl.h"
#include "instrumentation.h"
#include "intern_table.h"
#include "jit/jit.h"
#include "jit/profiling_info.h"
#include "jit/jit_scoped_code_cache_write.h"
#include "linear_alloc.h"
#include "oat/oat_file-inl.h"
#include "oat/oat_quick_method_header.h"
#include "object_callbacks.h"
#include "profile/profile_compilation_info.h"
#include "scoped_thread_state_change-inl.h"
#include "stack.h"
#include "thread-current-inl.h"
#include "thread-inl.h"
#include "thread_list.h"

namespace art HIDDEN {
namespace jit {

static constexpr size_t kCodeSizeLogThreshold = 50 * KB;
static constexpr size_t kStackMapSizeLogThreshold = 50 * KB;

class JitCodeCache::JniStubKey {
 public:
  explicit JniStubKey(ArtMethod* method) REQUIRES_SHARED(Locks::mutator_lock_)
      : shorty_(method->GetShorty()),
        is_static_(method->IsStatic()),
        is_fast_native_(method->IsFastNative()),
        is_critical_native_(method->IsCriticalNative()),
        is_synchronized_(method->IsSynchronized()) {
    DCHECK(!(is_fast_native_ && is_critical_native_));
  }

  bool operator<(const JniStubKey& rhs) const {
    if (is_static_ != rhs.is_static_) {
      return rhs.is_static_;
    }
    if (is_synchronized_ != rhs.is_synchronized_) {
      return rhs.is_synchronized_;
    }
    if (is_fast_native_ != rhs.is_fast_native_) {
      return rhs.is_fast_native_;
    }
    if (is_critical_native_ != rhs.is_critical_native_) {
      return rhs.is_critical_native_;
    }
    return strcmp(shorty_, rhs.shorty_) < 0;
  }

  // Update the shorty to point to another method's shorty. Call this function when removing
  // the method that references the old shorty from JniCodeData and not removing the entire
  // JniCodeData; the old shorty may become a dangling pointer when that method is unloaded.
  void UpdateShorty(ArtMethod* method) const REQUIRES_SHARED(Locks::mutator_lock_) {
    const char* shorty = method->GetShorty();
    DCHECK_STREQ(shorty_, shorty);
    shorty_ = shorty;
  }

 private:
  // The shorty points to a DexFile data and may need to change
  // to point to the same shorty in a different DexFile.
  mutable const char* shorty_;

  const bool is_static_;
  const bool is_fast_native_;
  const bool is_critical_native_;
  const bool is_synchronized_;
};

class JitCodeCache::JniStubData {
 public:
  JniStubData() : code_(nullptr), methods_() {}

  void SetCode(const void* code) {
    DCHECK(code != nullptr);
    code_ = code;
  }

  void UpdateEntryPoints(const void* entrypoint) REQUIRES_SHARED(Locks::mutator_lock_) {
    DCHECK(IsCompiled());
    DCHECK(entrypoint == OatQuickMethodHeader::FromCodePointer(GetCode())->GetEntryPoint());
    instrumentation::Instrumentation* instrum = Runtime::Current()->GetInstrumentation();
    for (ArtMethod* m : GetMethods()) {
      // Because `m` might be in the process of being deleted,
      //   - use the `ArtMethod::StillNeedsClinitCheckMayBeDead()` to check if
      //     we can update the entrypoint, and
      //   - call `Instrumentation::UpdateNativeMethodsCodeToJitCode` instead of the
      //     more generic function `Instrumentation::UpdateMethodsCode()`.
      // The `ArtMethod::StillNeedsClinitCheckMayBeDead()` checks the class status
      // in the to-space object if any even if the method's declaring class points to
      // the from-space class object. This way we do not miss updating an entrypoint
      // even under uncommon circumstances, when during a GC the class becomes visibly
      // initialized, the method becomes hot, we compile the thunk and want to update
      // the entrypoint while the method's declaring class field still points to the
      // from-space class object with the old status.
      if (!m->StillNeedsClinitCheckMayBeDead()) {
        instrum->UpdateNativeMethodsCodeToJitCode(m, entrypoint);
      }
    }
  }

  const void* GetCode() const {
    return code_;
  }

  bool IsCompiled() const {
    return GetCode() != nullptr;
  }

  void AddMethod(ArtMethod* method) {
    if (!ContainsElement(methods_, method)) {
      methods_.push_back(method);
    }
  }

  const std::vector<ArtMethod*>& GetMethods() const {
    return methods_;
  }

  void RemoveMethodsIn(const LinearAlloc& alloc) REQUIRES_SHARED(Locks::mutator_lock_) {
    auto kept_end = std::partition(
        methods_.begin(),
        methods_.end(),
        [&alloc](ArtMethod* method) { return !alloc.ContainsUnsafe(method); });
    for (auto it = kept_end; it != methods_.end(); it++) {
      VLOG(jit) << "JIT removed (JNI) " << (*it)->PrettyMethod() << ": " << code_;
    }
    methods_.erase(kept_end, methods_.end());
  }

  bool RemoveMethod(ArtMethod* method) REQUIRES_SHARED(Locks::mutator_lock_) {
    auto it = std::find(methods_.begin(), methods_.end(), method);
    if (it != methods_.end()) {
      VLOG(jit) << "JIT removed (JNI) " << (*it)->PrettyMethod() << ": " << code_;
      methods_.erase(it);
      return true;
    } else {
      return false;
    }
  }

  void MoveObsoleteMethod(ArtMethod* old_method, ArtMethod* new_method) {
    std::replace(methods_.begin(), methods_.end(), old_method, new_method);
  }

 private:
  const void* code_;
  std::vector<ArtMethod*> methods_;
};

JitCodeCache* JitCodeCache::Create(bool used_only_for_profile_data,
                                   bool rwx_memory_allowed,
                                   bool is_zygote,
                                   std::string* error_msg) {
  // Register for membarrier expedited sync core if JIT will be generating code.
  if (!used_only_for_profile_data) {
    if (art::membarrier(art::MembarrierCommand::kRegisterPrivateExpeditedSyncCore) != 0) {
      // MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE ensures that CPU instruction pipelines are
      // flushed and it's used when adding code to the JIT. The memory used by the new code may
      // have just been released and, in theory, the old code could still be in a pipeline.
      VLOG(jit) << "Kernel does not support membarrier sync-core";
    }
  }

  Runtime* runtime = Runtime::Current();
  size_t initial_capacity = runtime->GetJITOptions()->GetCodeCacheInitialCapacity();
  // Check whether the provided max capacity in options is below 1GB.
  size_t max_capacity = runtime->GetJITOptions()->GetCodeCacheMaxCapacity();
  // We need to have 32 bit offsets from method headers in code cache which point to things
  // in the data cache. If the maps are more than 4G apart, having multiple maps wouldn't work.
  // Ensure we're below 1 GB to be safe.
  if (max_capacity > 1 * GB) {
    std::ostringstream oss;
    oss << "Maxium code cache capacity is limited to 1 GB, "
        << PrettySize(max_capacity) << " is too big";
    *error_msg = oss.str();
    return nullptr;
  }

  MutexLock mu(Thread::Current(), *Locks::jit_lock_);
  JitMemoryRegion region;
  if (!region.Initialize(initial_capacity,
                         max_capacity,
                         rwx_memory_allowed,
                         is_zygote,
                         error_msg)) {
    return nullptr;
  }

  if (region.HasCodeMapping()) {
    const MemMap* exec_pages = region.GetExecPages();
    runtime->AddGeneratedCodeRange(exec_pages->Begin(), exec_pages->Size());
  }

  std::unique_ptr<JitCodeCache> jit_code_cache(new JitCodeCache());
  if (is_zygote) {
    // Zygote should never collect code to share the memory with the children.
    jit_code_cache->garbage_collect_code_ = false;
    jit_code_cache->shared_region_ = std::move(region);
  } else {
    jit_code_cache->private_region_ = std::move(region);
  }

  VLOG(jit) << "Created jit code cache: initial capacity="
            << PrettySize(initial_capacity)
            << ", maximum capacity="
            << PrettySize(max_capacity);

  return jit_code_cache.release();
}

JitCodeCache::JitCodeCache()
    : is_weak_access_enabled_(true),
      inline_cache_cond_("Jit inline cache condition variable", *Locks::jit_lock_),
      reserved_capacity_(GetInitialCapacity() * kReservedCapacityMultiplier),
      zygote_map_(&shared_region_),
      lock_cond_("Jit code cache condition variable", *Locks::jit_lock_),
      collection_in_progress_(false),
      garbage_collect_code_(true),
      number_of_baseline_compilations_(0),
      number_of_optimized_compilations_(0),
      number_of_osr_compilations_(0),
      number_of_collections_(0),
      histogram_stack_map_memory_use_("Memory used for stack maps", 16),
      histogram_code_memory_use_("Memory used for compiled code", 16),
      histogram_profiling_info_memory_use_("Memory used for profiling info", 16) {
}

JitCodeCache::~JitCodeCache() {
  if (private_region_.HasCodeMapping()) {
    const MemMap* exec_pages = private_region_.GetExecPages();
    Runtime::Current()->RemoveGeneratedCodeRange(exec_pages->Begin(), exec_pages->Size());
  }
  if (shared_region_.HasCodeMapping()) {
    const MemMap* exec_pages = shared_region_.GetExecPages();
    Runtime::Current()->RemoveGeneratedCodeRange(exec_pages->Begin(), exec_pages->Size());
  }
}

bool JitCodeCache::PrivateRegionContainsPc(const void* ptr) const {
  return private_region_.IsInExecSpace(ptr);
}

bool JitCodeCache::ContainsPc(const void* ptr) const {
  return PrivateRegionContainsPc(ptr) || shared_region_.IsInExecSpace(ptr);
}

bool JitCodeCache::ContainsMethod(ArtMethod* method) {
  Thread* self = Thread::Current();
  ScopedDebugDisallowReadBarriers sddrb(self);
  MutexLock mu(self, *Locks::jit_lock_);
  if (UNLIKELY(method->IsNative())) {
    auto it = jni_stubs_map_.find(JniStubKey(method));
    if (it != jni_stubs_map_.end() &&
        it->second.IsCompiled() &&
        ContainsElement(it->second.GetMethods(), method)) {
      return true;
    }
  } else {
    for (const auto& it : method_code_map_) {
      if (it.second == method) {
        return true;
      }
    }
    if (zygote_map_.ContainsMethod(method)) {
      return true;
    }
  }
  return false;
}

const void* JitCodeCache::GetJniStubCode(ArtMethod* method) {
  DCHECK(method->IsNative());
  Thread* self = Thread::Current();
  ScopedDebugDisallowReadBarriers sddrb(self);
  MutexLock mu(self, *Locks::jit_lock_);
  auto it = jni_stubs_map_.find(JniStubKey(method));
  if (it != jni_stubs_map_.end()) {
    JniStubData& data = it->second;
    if (data.IsCompiled() && ContainsElement(data.GetMethods(), method)) {
      return data.GetCode();
    }
  }
  return nullptr;
}

const void* JitCodeCache::GetSavedEntryPointOfPreCompiledMethod(ArtMethod* method) {
  Thread* self = Thread::Current();
  ScopedDebugDisallowReadBarriers sddrb(self);
  if (method->IsPreCompiled()) {
    const void* code_ptr = nullptr;
    if (method->GetDeclaringClass<kWithoutReadBarrier>()->IsBootStrapClassLoaded()) {
      code_ptr = zygote_map_.GetCodeFor(method);
    } else {
      MutexLock mu(self, *Locks::jit_lock_);
      auto it = saved_compiled_methods_map_.find(method);
      if (it != saved_compiled_methods_map_.end()) {
        code_ptr = it->second;
      }
    }
    if (code_ptr != nullptr) {
      OatQuickMethodHeader* method_header = OatQuickMethodHeader::FromCodePointer(code_ptr);
      return method_header->GetEntryPoint();
    }
  }
  return nullptr;
}

bool JitCodeCache::WaitForPotentialCollectionToComplete(Thread* self) {
  bool in_collection = false;
  while (collection_in_progress_) {
    in_collection = true;
    lock_cond_.Wait(self);
  }
  return in_collection;
}

static uintptr_t FromCodeToAllocation(const void* code) {
  size_t alignment = GetInstructionSetCodeAlignment(kRuntimeISA);
  return reinterpret_cast<uintptr_t>(code) - RoundUp(sizeof(OatQuickMethodHeader), alignment);
}

static const void* FromAllocationToCode(const uint8_t* alloc) {
  size_t alignment = GetInstructionSetCodeAlignment(kRuntimeISA);
  return reinterpret_cast<const void*>(alloc + RoundUp(sizeof(OatQuickMethodHeader), alignment));
}

static uint32_t GetNumberOfRoots(const uint8_t* stack_map) {
  // The length of the table is stored just before the stack map (and therefore at the end of
  // the table itself), in order to be able to fetch it from a `stack_map` pointer.
  return reinterpret_cast<const uint32_t*>(stack_map)[-1];
}

static void DCheckRootsAreValid(const std::vector<Handle<mirror::Object>>& roots,
                                bool is_shared_region)
    REQUIRES(!Locks::intern_table_lock_) REQUIRES_SHARED(Locks::mutator_lock_) {
  if (!kIsDebugBuild) {
    return;
  }
  // Put all roots in `roots_data`.
  for (Handle<mirror::Object> object : roots) {
    // Ensure the string is strongly interned. b/32995596
    if (object->IsString()) {
      ObjPtr<mirror::String> str = object->AsString();
      ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
      CHECK(class_linker->GetInternTable()->LookupStrong(Thread::Current(), str) != nullptr);
    }
    // Ensure that we don't put movable objects in the shared region.
    if (is_shared_region) {
      CHECK(!Runtime::Current()->GetHeap()->IsMovableObject(object.Get()));
    }
  }
}

static const uint8_t* GetRootTable(const void* code_ptr, uint32_t* number_of_roots = nullptr) {
  OatQuickMethodHeader* method_header = OatQuickMethodHeader::FromCodePointer(code_ptr);
  uint8_t* data = method_header->GetOptimizedCodeInfoPtr();
  uint32_t roots = GetNumberOfRoots(data);
  if (number_of_roots != nullptr) {
    *number_of_roots = roots;
  }
  return data - ComputeRootTableSize(roots);
}

void JitCodeCache::SweepRootTables(IsMarkedVisitor* visitor) {
  Thread* self = Thread::Current();
  ScopedDebugDisallowReadBarriers sddrb(self);
  MutexLock mu(self, *Locks::jit_lock_);
  for (const auto& entry : method_code_map_) {
    uint32_t number_of_roots = 0;
    const uint8_t* root_table = GetRootTable(entry.first, &number_of_roots);
    uint8_t* roots_data = private_region_.IsInDataSpace(root_table)
        ? private_region_.GetWritableDataAddress(root_table)
        : shared_region_.GetWritableDataAddress(root_table);
    GcRoot<mirror::Object>* roots = reinterpret_cast<GcRoot<mirror::Object>*>(roots_data);
    for (uint32_t i = 0; i < number_of_roots; ++i) {
      // This does not need a read barrier because this is called by GC.
      mirror::Object* object = roots[i].Read<kWithoutReadBarrier>();
      if (object == nullptr || object == Runtime::GetWeakClassSentinel()) {
        // entry got deleted in a previous sweep.
      } else if (object->IsString<kDefaultVerifyFlags>()) {
        mirror::Object* new_object = visitor->IsMarked(object);
        // We know the string is marked because it's a strongly-interned string that
        // is always alive.
        // TODO: Do not use IsMarked for j.l.Class, and adjust once we move this method
        // out of the weak access/creation pause. b/32167580
        DCHECK_NE(new_object, nullptr) << "old-string:" << object;
        if (new_object != object) {
          roots[i] = GcRoot<mirror::Object>(new_object);
        }
      } else {
        mirror::Object* new_klass = visitor->IsMarked(object);
        if (new_klass == nullptr) {
          roots[i] = GcRoot<mirror::Object>(Runtime::GetWeakClassSentinel());
        } else if (new_klass != object) {
          roots[i] = GcRoot<mirror::Object>(new_klass);
        }
      }
    }
  }
  // Walk over inline caches to clear entries containing unloaded classes.
  for (auto it : profiling_infos_) {
    ProfilingInfo* info = it.second;
    InlineCache* caches = info->GetInlineCaches();
    for (size_t i = 0; i < info->number_of_inline_caches_; ++i) {
      InlineCache* cache = &caches[i];
      for (size_t j = 0; j < InlineCache::kIndividualCacheSize; ++j) {
        mirror::Class* klass = cache->classes_[j].Read<kWithoutReadBarrier>();
        if (klass != nullptr) {
          mirror::Class* new_klass = down_cast<mirror::Class*>(visitor->IsMarked(klass));
          if (new_klass != klass) {
            cache->classes_[j] = GcRoot<mirror::Class>(new_klass);
          }
        }
      }
    }
  }
}

void JitCodeCache::FreeCodeAndData(const void* code_ptr) {
  if (IsInZygoteExecSpace(code_ptr)) {
    // No need to free, this is shared memory.
    return;
  }
  uintptr_t allocation = FromCodeToAllocation(code_ptr);
  const uint8_t* data = nullptr;
  if (OatQuickMethodHeader::FromCodePointer(code_ptr)->IsOptimized()) {
    data = GetRootTable(code_ptr);
  }  // else this is a JNI stub without any data.

  FreeLocked(&private_region_, reinterpret_cast<uint8_t*>(allocation), data);
}

void JitCodeCache::FreeAllMethodHeaders(
    const std::unordered_set<OatQuickMethodHeader*>& method_headers) {
  // We need to remove entries in method_headers from CHA dependencies
  // first since once we do FreeCode() below, the memory can be reused
  // so it's possible for the same method_header to start representing
  // different compile code.
  {
    MutexLock mu2(Thread::Current(), *Locks::cha_lock_);
    Runtime::Current()->GetClassLinker()->GetClassHierarchyAnalysis()
        ->RemoveDependentsWithMethodHeaders(method_headers);
  }

  ScopedCodeCacheWrite scc(private_region_);
  for (const OatQuickMethodHeader* method_header : method_headers) {
    FreeCodeAndData(method_header->GetCode());
  }

  // We have potentially removed a lot of debug info. Do maintenance pass to save space.
  RepackNativeDebugInfoForJit();

  // Check that the set of compiled methods exactly matches native debug information.
  // Does not check zygote methods since they can change concurrently.
  if (kIsDebugBuild && !Runtime::Current()->IsZygote()) {
    std::map<const void*, ArtMethod*> compiled_methods;
    VisitAllMethods([&](const void* addr, ArtMethod* method) {
      if (!IsInZygoteExecSpace(addr)) {
        CHECK(addr != nullptr && method != nullptr);
        compiled_methods.emplace(addr, method);
      }
    });
    std::set<const void*> debug_info;
    ForEachNativeDebugSymbol([&](const void* addr, size_t, const char* name) {
      addr = AlignDown(addr, GetInstructionSetInstructionAlignment(kRuntimeISA));  // Thumb-bit.
      CHECK(debug_info.emplace(addr).second) << "Duplicate debug info: " << addr << " " << name;
      CHECK_EQ(compiled_methods.count(addr), 1u) << "Extra debug info: " << addr << " " << name;
    });
    if (!debug_info.empty()) {  // If debug-info generation is enabled.
      for (auto it : compiled_methods) {
        CHECK_EQ(debug_info.count(it.first), 1u) << "No debug info: " << it.second->PrettyMethod();
      }
      CHECK_EQ(compiled_methods.size(), debug_info.size());
    }
  }
}

void JitCodeCache::RemoveMethodsIn(Thread* self, const LinearAlloc& alloc) {
  ScopedTrace trace(__PRETTY_FUNCTION__);
  ScopedDebugDisallowReadBarriers sddrb(self);
  // We use a set to first collect all method_headers whose code need to be
  // removed. We need to free the underlying code after we remove CHA dependencies
  // for entries in this set. And it's more efficient to iterate through
  // the CHA dependency map just once with an unordered_set.
  std::unordered_set<OatQuickMethodHeader*> method_headers;
  {
    MutexLock mu(self, *Locks::jit_lock_);
    // We do not check if a code cache GC is in progress, as this method comes
    // with the classlinker_classes_lock_ held, and suspending ourselves could
    // lead to a deadlock.
    {
      for (auto it = jni_stubs_map_.begin(); it != jni_stubs_map_.end();) {
        it->second.RemoveMethodsIn(alloc);
        if (it->second.GetMethods().empty()) {
          method_headers.insert(OatQuickMethodHeader::FromCodePointer(it->second.GetCode()));
          it = jni_stubs_map_.erase(it);
        } else {
          it->first.UpdateShorty(it->second.GetMethods().front());
          ++it;
        }
      }
      for (auto it = method_code_map_.begin(); it != method_code_map_.end();) {
        if (alloc.ContainsUnsafe(it->second)) {
          method_headers.insert(OatQuickMethodHeader::FromCodePointer(it->first));
          VLOG(jit) << "JIT removed " << it->second->PrettyMethod() << ": " << it->first;
          it = method_code_map_.erase(it);
        } else {
          ++it;
        }
      }
    }
    for (auto it = osr_code_map_.begin(); it != osr_code_map_.end();) {
      if (alloc.ContainsUnsafe(it->first)) {
        // Note that the code has already been pushed to method_headers in the loop
        // above and is going to be removed in FreeCode() below.
        it = osr_code_map_.erase(it);
      } else {
        ++it;
      }
    }
    for (auto it = profiling_infos_.begin(); it != profiling_infos_.end();) {
      ProfilingInfo* info = it->second;
      if (alloc.ContainsUnsafe(info->GetMethod())) {
        private_region_.FreeWritableData(reinterpret_cast<uint8_t*>(info));
        it = profiling_infos_.erase(it);
      } else {
        ++it;
      }
    }
    FreeAllMethodHeaders(method_headers);
  }
}

bool JitCodeCache::IsWeakAccessEnabled(Thread* self) const {
  return gUseReadBarrier
      ? self->GetWeakRefAccessEnabled()
      : is_weak_access_enabled_.load(std::memory_order_seq_cst);
}

void JitCodeCache::WaitUntilInlineCacheAccessible(Thread* self) {
  if (IsWeakAccessEnabled(self)) {
    return;
  }
  ScopedThreadSuspension sts(self, ThreadState::kWaitingWeakGcRootRead);
  MutexLock mu(self, *Locks::jit_lock_);
  while (!IsWeakAccessEnabled(self)) {
    inline_cache_cond_.Wait(self);
  }
}

void JitCodeCache::BroadcastForInlineCacheAccess() {
  Thread* self = Thread::Current();
  MutexLock mu(self, *Locks::jit_lock_);
  inline_cache_cond_.Broadcast(self);
}

void JitCodeCache::AllowInlineCacheAccess() {
  DCHECK(!gUseReadBarrier);
  is_weak_access_enabled_.store(true, std::memory_order_seq_cst);
  BroadcastForInlineCacheAccess();
}

void JitCodeCache::DisallowInlineCacheAccess() {
  DCHECK(!gUseReadBarrier);
  is_weak_access_enabled_.store(false, std::memory_order_seq_cst);
}

void JitCodeCache::CopyInlineCacheInto(
    const InlineCache& ic,
    /*out*/StackHandleScope<InlineCache::kIndividualCacheSize>* classes) {
  static_assert(arraysize(ic.classes_) == InlineCache::kIndividualCacheSize);
  DCHECK_EQ(classes->Capacity(), InlineCache::kIndividualCacheSize);
  DCHECK_EQ(classes->Size(), 0u);
  WaitUntilInlineCacheAccessible(Thread::Current());
  // Note that we don't need to lock `lock_` here, the compiler calling
  // this method has already ensured the inline cache will not be deleted.
  for (const GcRoot<mirror::Class>& root : ic.classes_) {
    mirror::Class* object = root.Read();
    if (object != nullptr) {
      DCHECK_LT(classes->Size(), classes->Capacity());
      classes->NewHandle(object);
    }
  }
}

static void ClearMethodCounter(ArtMethod* method, bool was_warm)
    REQUIRES_SHARED(Locks::mutator_lock_) {
  if (was_warm) {
    method->SetPreviouslyWarm();
  }
  method->ResetCounter(Runtime::Current()->GetJITOptions()->GetWarmupThreshold());
  // We add one sample so that the profile knows that the method was executed at least once.
  // This is required for layout purposes.
  method->UpdateCounter(/* new_samples= */ 1);
}

void JitCodeCache::WaitForPotentialCollectionToCompleteRunnable(Thread* self) {
  while (collection_in_progress_) {
    Locks::jit_lock_->Unlock(self);
    {
      ScopedThreadSuspension sts(self, ThreadState::kSuspended);
      MutexLock mu(self, *Locks::jit_lock_);
      WaitForPotentialCollectionToComplete(self);
    }
    Locks::jit_lock_->Lock(self);
  }
}

bool JitCodeCache::Commit(Thread* self,
                          JitMemoryRegion* region,
                          ArtMethod* method,
                          ArrayRef<const uint8_t> reserved_code,
                          ArrayRef<const uint8_t> code,
                          ArrayRef<const uint8_t> reserved_data,
                          const std::vector<Handle<mirror::Object>>& roots,
                          ArrayRef<const uint8_t> stack_map,
                          const std::vector<uint8_t>& debug_info,
                          bool is_full_debug_info,
                          CompilationKind compilation_kind,
                          const ArenaSet<ArtMethod*>& cha_single_implementation_list) {
  DCHECK_IMPLIES(method->IsNative(), (compilation_kind != CompilationKind::kOsr));

  if (!method->IsNative()) {
    // We need to do this before grabbing the lock_ because it needs to be able to see the string
    // InternTable. Native methods do not have roots.
    DCheckRootsAreValid(roots, IsSharedRegion(*region));
  }

  const uint8_t* roots_data = reserved_data.data();
  size_t root_table_size = ComputeRootTableSize(roots.size());
  const uint8_t* stack_map_data = roots_data + root_table_size;

  OatQuickMethodHeader* method_header = nullptr;
  {
    MutexLock mu(self, *Locks::jit_lock_);
    // We need to make sure that there will be no jit-gcs going on and wait for any ongoing one to
    // finish.
    WaitForPotentialCollectionToCompleteRunnable(self);
    const uint8_t* code_ptr = region->CommitCode(reserved_code, code, stack_map_data);
    if (code_ptr == nullptr) {
      return false;
    }
    method_header = OatQuickMethodHeader::FromCodePointer(code_ptr);

    // Commit roots and stack maps before updating the entry point.
    if (!region->CommitData(reserved_data, roots, stack_map)) {
      return false;
    }

    switch (compilation_kind) {
      case CompilationKind::kOsr:
        number_of_osr_compilations_++;
        break;
      case CompilationKind::kBaseline:
        number_of_baseline_compilations_++;
        break;
      case CompilationKind::kOptimized:
        number_of_optimized_compilations_++;
        break;
    }

    // We need to update the debug info before the entry point gets set.
    // At the same time we want to do under JIT lock so that debug info and JIT maps are in sync.
    if (!debug_info.empty()) {
      // NB: Don't allow packing of full info since it would remove non-backtrace data.
      AddNativeDebugInfoForJit(code_ptr, debug_info, /*allow_packing=*/ !is_full_debug_info);
    }

    // The following needs to be guarded by cha_lock_ also. Otherwise it's possible that the
    // compiled code is considered invalidated by some class linking, but below we still make the
    // compiled code valid for the method.  Need cha_lock_ for checking all single-implementation
    // flags and register dependencies.
    {
      ScopedDebugDisallowReadBarriers sddrb(self);
      MutexLock cha_mu(self, *Locks::cha_lock_);
      bool single_impl_still_valid = true;
      for (ArtMethod* single_impl : cha_single_implementation_list) {
        if (!single_impl->HasSingleImplementation()) {
          // Simply discard the compiled code. Clear the counter so that it may be recompiled later.
          // Hopefully the class hierarchy will be more stable when compilation is retried.
          single_impl_still_valid = false;
          ClearMethodCounter(method, /*was_warm=*/ false);
          break;
        }
      }

      // Discard the code if any single-implementation assumptions are now invalid.
      if (UNLIKELY(!single_impl_still_valid)) {
        VLOG(jit) << "JIT discarded jitted code due to invalid single-implementation assumptions.";
        return false;
      }
      DCHECK(cha_single_implementation_list.empty() || !Runtime::Current()->IsJavaDebuggable())
          << "Should not be using cha on debuggable apps/runs!";

      ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
      for (ArtMethod* single_impl : cha_single_implementation_list) {
        class_linker->GetClassHierarchyAnalysis()->AddDependency(
            single_impl, method, method_header);
      }
    }

    if (UNLIKELY(method->IsNative())) {
      ScopedDebugDisallowReadBarriers sddrb(self);
      auto it = jni_stubs_map_.find(JniStubKey(method));
      DCHECK(it != jni_stubs_map_.end())
          << "Entry inserted in NotifyCompilationOf() should be alive.";
      JniStubData* data = &it->second;
      DCHECK(ContainsElement(data->GetMethods(), method))
          << "Entry inserted in NotifyCompilationOf() should contain this method.";
      data->SetCode(code_ptr);
      data->UpdateEntryPoints(method_header->GetEntryPoint());
    } else {
      if (method->IsPreCompiled() && IsSharedRegion(*region)) {
        ScopedDebugDisallowReadBarriers sddrb(self);
        zygote_map_.Put(code_ptr, method);
      } else {
        ScopedDebugDisallowReadBarriers sddrb(self);
        method_code_map_.Put(code_ptr, method);
      }
      if (compilation_kind == CompilationKind::kOsr) {
        ScopedDebugDisallowReadBarriers sddrb(self);
        osr_code_map_.Put(method, code_ptr);
      } else if (method->StillNeedsClinitCheck()) {
        ScopedDebugDisallowReadBarriers sddrb(self);
        // This situation currently only occurs in the jit-zygote mode.
        DCHECK(!garbage_collect_code_);
        DCHECK(method->IsPreCompiled());
        // The shared region can easily be queried. For the private region, we
        // use a side map.
        if (!IsSharedRegion(*region)) {
          saved_compiled_methods_map_.Put(method, code_ptr);
        }
      } else {
        Runtime::Current()->GetInstrumentation()->UpdateMethodsCode(
            method, method_header->GetEntryPoint());
      }
    }
    if (collection_in_progress_) {
      // We need to update the live bitmap if there is a GC to ensure it sees this new
      // code.
      GetLiveBitmap()->AtomicTestAndSet(FromCodeToAllocation(code_ptr));
    }
    VLOG(jit)
        << "JIT added (kind=" << compilation_kind << ") "
        << ArtMethod::PrettyMethod(method) << "@" << method
        << " ccache_size=" << PrettySize(CodeCacheSizeLocked()) << ": "
        << " dcache_size=" << PrettySize(DataCacheSizeLocked()) << ": "
        << reinterpret_cast<const void*>(method_header->GetEntryPoint()) << ","
        << reinterpret_cast<const void*>(method_header->GetEntryPoint() +
                                         method_header->GetCodeSize());
  }

  if (kIsDebugBuild) {
    uintptr_t entry_point = reinterpret_cast<uintptr_t>(method_header->GetEntryPoint());
    DCHECK_EQ(LookupMethodHeader(entry_point, method), method_header) << method->PrettyMethod();
    DCHECK_EQ(LookupMethodHeader(entry_point + method_header->GetCodeSize() - 1, method),
              method_header) << method->PrettyMethod();
  }
  return true;
}

size_t JitCodeCache::CodeCacheSize() {
  MutexLock mu(Thread::Current(), *Locks::jit_lock_);
  return CodeCacheSizeLocked();
}

bool JitCodeCache::RemoveMethod(ArtMethod* method, bool release_memory) {
  // This function is used only for testing and only with non-native methods.
  CHECK(!method->IsNative());

  Thread* self = Thread::Current();
  ScopedDebugDisallowReadBarriers sddrb(self);
  MutexLock mu(self, *Locks::jit_lock_);

  bool osr = osr_code_map_.find(method) != osr_code_map_.end();
  bool in_cache = RemoveMethodLocked(method, release_memory);

  if (!in_cache) {
    return false;
  }

  ClearMethodCounter(method, /* was_warm= */ false);
  Runtime::Current()->GetInstrumentation()->InitializeMethodsCode(method, /*aot_code=*/ nullptr);
  VLOG(jit)
      << "JIT removed (osr=" << std::boolalpha << osr << std::noboolalpha << ") "
      << ArtMethod::PrettyMethod(method) << "@" << method
      << " ccache_size=" << PrettySize(CodeCacheSizeLocked()) << ": "
      << " dcache_size=" << PrettySize(DataCacheSizeLocked());
  return true;
}

bool JitCodeCache::RemoveMethodLocked(ArtMethod* method, bool release_memory) {
  if (LIKELY(!method->IsNative())) {
    auto it = profiling_infos_.find(method);
    if (it != profiling_infos_.end()) {
      profiling_infos_.erase(it);
    }
  }

  bool in_cache = false;
  ScopedCodeCacheWrite ccw(private_region_);
  if (UNLIKELY(method->IsNative())) {
    auto it = jni_stubs_map_.find(JniStubKey(method));
    if (it != jni_stubs_map_.end() && it->second.RemoveMethod(method)) {
      in_cache = true;
      if (it->second.GetMethods().empty()) {
        if (release_memory) {
          FreeCodeAndData(it->second.GetCode());
        }
        jni_stubs_map_.erase(it);
      } else {
        it->first.UpdateShorty(it->second.GetMethods().front());
      }
    }
  } else {
    for (auto it = method_code_map_.begin(); it != method_code_map_.end();) {
      if (it->second == method) {
        in_cache = true;
        if (release_memory) {
          FreeCodeAndData(it->first);
        }
        VLOG(jit) << "JIT removed " << it->second->PrettyMethod() << ": " << it->first;
        it = method_code_map_.erase(it);
      } else {
        ++it;
      }
    }

    auto osr_it = osr_code_map_.find(method);
    if (osr_it != osr_code_map_.end()) {
      osr_code_map_.erase(osr_it);
    }
  }

  return in_cache;
}

// This notifies the code cache that the given method has been redefined and that it should remove
// any cached information it has on the method. All threads must be suspended before calling this
// method. The compiled code for the method (if there is any) must not be in any threads call stack.
void JitCodeCache::NotifyMethodRedefined(ArtMethod* method) {
  Thread* self = Thread::Current();
  ScopedDebugDisallowReadBarriers sddrb(self);
  MutexLock mu(self, *Locks::jit_lock_);
  RemoveMethodLocked(method, /* release_memory= */ true);
}

// This invalidates old_method. Once this function returns one can no longer use old_method to
// execute code unless it is fixed up. This fixup will happen later in the process of installing a
// class redefinition.
// TODO We should add some info to ArtMethod to note that 'old_method' has been invalidated and
// shouldn't be used since it is no longer logically in the jit code cache.
// TODO We should add DCHECKS that validate that the JIT is paused when this method is entered.
void JitCodeCache::MoveObsoleteMethod(ArtMethod* old_method, ArtMethod* new_method) {
  Thread* self = Thread::Current();
  ScopedDebugDisallowReadBarriers sddrb(self);
  MutexLock mu(self, *Locks::jit_lock_);
  if (old_method->IsNative()) {
    // Update methods in jni_stubs_map_.
    for (auto& entry : jni_stubs_map_) {
      JniStubData& data = entry.second;
      data.MoveObsoleteMethod(old_method, new_method);
    }
    return;
  }
  // Update method_code_map_ to point to the new method.
  for (auto& it : method_code_map_) {
    if (it.second == old_method) {
      it.second = new_method;
    }
  }
  // Update osr_code_map_ to point to the new method.
  auto code_map = osr_code_map_.find(old_method);
  if (code_map != osr_code_map_.end()) {
    osr_code_map_.Put(new_method, code_map->second);
    osr_code_map_.erase(old_method);
  }
}

void JitCodeCache::TransitionToDebuggable() {
  // Check that none of our methods have an entrypoint in the zygote exec
  // space (this should be taken care of by
  // ClassLinker::UpdateEntryPointsClassVisitor.
  Thread* self = Thread::Current();
  ScopedDebugDisallowReadBarriers sddrb(self);
  {
    MutexLock mu(self, *Locks::jit_lock_);
    if (kIsDebugBuild) {
      // TODO: Check `jni_stubs_map_`?
      for (const auto& entry : method_code_map_) {
        ArtMethod* method = entry.second;
        DCHECK(!method->IsPreCompiled());
        DCHECK(!IsInZygoteExecSpace(method->GetEntryPointFromQuickCompiledCode()));
      }
    }
    // Not strictly necessary, but this map is useless now.
    saved_compiled_methods_map_.clear();
  }
  if (kIsDebugBuild) {
    for (const auto& entry : zygote_map_) {
      ArtMethod* method = entry.method;
      if (method != nullptr) {
        DCHECK(!method->IsPreCompiled());
        DCHECK(!IsInZygoteExecSpace(method->GetEntryPointFromQuickCompiledCode()));
      }
    }
  }
}

size_t JitCodeCache::CodeCacheSizeLocked() {
  return GetCurrentRegion()->GetUsedMemoryForCode();
}

size_t JitCodeCache::DataCacheSize() {
  MutexLock mu(Thread::Current(), *Locks::jit_lock_);
  return DataCacheSizeLocked();
}

size_t JitCodeCache::DataCacheSizeLocked() {
  return GetCurrentRegion()->GetUsedMemoryForData();
}

bool JitCodeCache::Reserve(Thread* self,
                           JitMemoryRegion* region,
                           size_t code_size,
                           size_t stack_map_size,
                           size_t number_of_roots,
                           ArtMethod* method,
                           /*out*/ArrayRef<const uint8_t>* reserved_code,
                           /*out*/ArrayRef<const uint8_t>* reserved_data) {
  code_size = OatQuickMethodHeader::InstructionAlignedSize() + code_size;
  size_t data_size = RoundUp(ComputeRootTableSize(number_of_roots) + stack_map_size, sizeof(void*));

  const uint8_t* code;
  const uint8_t* data;
  while (true) {
    bool at_max_capacity = false;
    {
      ScopedThreadSuspension sts(self, ThreadState::kSuspended);
      MutexLock mu(self, *Locks::jit_lock_);
      WaitForPotentialCollectionToComplete(self);
      ScopedCodeCacheWrite ccw(*region);
      code = region->AllocateCode(code_size);
      data = region->AllocateData(data_size);
      at_max_capacity = IsAtMaxCapacity();
    }
    if (code != nullptr && data != nullptr) {
      break;
    }
    Free(self, region, code, data);
    if (at_max_capacity) {
      VLOG(jit) << "JIT failed to allocate code of size "
                << PrettySize(code_size)
                << ", and data of size "
                << PrettySize(data_size);
      return false;
    }
    // Run a code cache collection and try again.
    GarbageCollectCache(self);
  }

  *reserved_code = ArrayRef<const uint8_t>(code, code_size);
  *reserved_data = ArrayRef<const uint8_t>(data, data_size);

  MutexLock mu(self, *Locks::jit_lock_);
  histogram_code_memory_use_.AddValue(code_size);
  if (code_size > kCodeSizeLogThreshold) {
    LOG(INFO) << "JIT allocated "
              << PrettySize(code_size)
              << " for compiled code of "
              << ArtMethod::PrettyMethod(method);
  }
  histogram_stack_map_memory_use_.AddValue(data_size);
  if (data_size > kStackMapSizeLogThreshold) {
    LOG(INFO) << "JIT allocated "
              << PrettySize(data_size)
              << " for stack maps of "
              << ArtMethod::PrettyMethod(method);
  }
  return true;
}

void JitCodeCache::Free(Thread* self,
                        JitMemoryRegion* region,
                        const uint8_t* code,
                        const uint8_t* data) {
  MutexLock mu(self, *Locks::jit_lock_);
  ScopedCodeCacheWrite ccw(*region);
  FreeLocked(region, code, data);
}

void JitCodeCache::FreeLocked(JitMemoryRegion* region, const uint8_t* code, const uint8_t* data) {
  if (code != nullptr) {
    RemoveNativeDebugInfoForJit(reinterpret_cast<const void*>(FromAllocationToCode(code)));
    region->FreeCode(code);
  }
  if (data != nullptr) {
    region->FreeData(data);
  }
}

class MarkCodeClosure final : public Closure {
 public:
  MarkCodeClosure(JitCodeCache* code_cache, CodeCacheBitmap* bitmap, Barrier* barrier)
      : code_cache_(code_cache), bitmap_(bitmap), barrier_(barrier) {}

  void Run(Thread* thread) override REQUIRES_SHARED(Locks::mutator_lock_) {
    ScopedTrace trace(__PRETTY_FUNCTION__);
    DCHECK(thread == Thread::Current() || thread->IsSuspended());
    StackVisitor::WalkStack(
        [&](const art::StackVisitor* stack_visitor) {
          const OatQuickMethodHeader* method_header =
              stack_visitor->GetCurrentOatQuickMethodHeader();
          if (method_header == nullptr) {
            return true;
          }
          const void* code = method_header->GetCode();
          if (code_cache_->ContainsPc(code) && !code_cache_->IsInZygoteExecSpace(code)) {
            // Use the atomic set version, as multiple threads are executing this code.
            bitmap_->AtomicTestAndSet(FromCodeToAllocation(code));
          }
          return true;
        },
        thread,
        /* context= */ nullptr,
        art::StackVisitor::StackWalkKind::kSkipInlinedFrames);

    barrier_->Pass(Thread::Current());
  }

 private:
  JitCodeCache* const code_cache_;
  CodeCacheBitmap* const bitmap_;
  Barrier* const barrier_;
};

void JitCodeCache::NotifyCollectionDone(Thread* self) {
  collection_in_progress_ = false;
  lock_cond_.Broadcast(self);
}

void JitCodeCache::MarkCompiledCodeOnThreadStacks(Thread* self) {
  Barrier barrier(0);
  size_t threads_running_checkpoint = 0;
  MarkCodeClosure closure(this, GetLiveBitmap(), &barrier);
  threads_running_checkpoint = Runtime::Current()->GetThreadList()->RunCheckpoint(&closure);
  // Now that we have run our checkpoint, move to a suspended state and wait
  // for other threads to run the checkpoint.
  ScopedThreadSuspension sts(self, ThreadState::kSuspended);
  if (threads_running_checkpoint != 0) {
    barrier.Increment(self, threads_running_checkpoint);
  }
}

bool JitCodeCache::IsAtMaxCapacity() const {
  return private_region_.GetCurrentCapacity() == private_region_.GetMaxCapacity();
}

void JitCodeCache::GarbageCollectCache(Thread* self) {
  ScopedTrace trace(__FUNCTION__);
  // Wait for an existing collection, or let everyone know we are starting one.
  {
    ScopedThreadSuspension sts(self, ThreadState::kSuspended);
    MutexLock mu(self, *Locks::jit_lock_);
    if (!garbage_collect_code_) {
      private_region_.IncreaseCodeCacheCapacity();
      return;
    } else if (WaitForPotentialCollectionToComplete(self)) {
      return;
    } else {
      number_of_collections_++;
      live_bitmap_.reset(CodeCacheBitmap::Create(
          "code-cache-bitmap",
          reinterpret_cast<uintptr_t>(private_region_.GetExecPages()->Begin()),
          reinterpret_cast<uintptr_t>(
              private_region_.GetExecPages()->Begin() + private_region_.GetCurrentCapacity() / 2)));
      collection_in_progress_ = true;
    }
  }

  TimingLogger logger("JIT code cache timing logger", true, VLOG_IS_ON(jit));
  {
    TimingLogger::ScopedTiming st("Code cache collection", &logger);

    VLOG(jit) << "Do code cache collection, code="
              << PrettySize(CodeCacheSize())
              << ", data=" << PrettySize(DataCacheSize());

    DoCollection(self);

    VLOG(jit) << "After code cache collection, code="
              << PrettySize(CodeCacheSize())
              << ", data=" << PrettySize(DataCacheSize());

    {
      MutexLock mu(self, *Locks::jit_lock_);
      private_region_.IncreaseCodeCacheCapacity();
      live_bitmap_.reset(nullptr);
      NotifyCollectionDone(self);
    }
  }
  Runtime::Current()->GetJit()->AddTimingLogger(logger);
}

void JitCodeCache::RemoveUnmarkedCode(Thread* self) {
  ScopedTrace trace(__FUNCTION__);
  ScopedDebugDisallowReadBarriers sddrb(self);
  std::unordered_set<OatQuickMethodHeader*> method_headers;
  {
    MutexLock mu(self, *Locks::jit_lock_);
    // Iterate over all compiled code and remove entries that are not marked.
    for (auto it = jni_stubs_map_.begin(); it != jni_stubs_map_.end();) {
      JniStubData* data = &it->second;
      if (IsInZygoteExecSpace(data->GetCode()) ||
          !data->IsCompiled() ||
          GetLiveBitmap()->Test(FromCodeToAllocation(data->GetCode()))) {
        ++it;
      } else {
        method_headers.insert(OatQuickMethodHeader::FromCodePointer(data->GetCode()));
        for (ArtMethod* method : data->GetMethods()) {
          VLOG(jit) << "JIT removed (JNI) " << method->PrettyMethod() << ": " << data->GetCode();
        }
        it = jni_stubs_map_.erase(it);
      }
    }
    for (auto it = method_code_map_.begin(); it != method_code_map_.end();) {
      const void* code_ptr = it->first;
      uintptr_t allocation = FromCodeToAllocation(code_ptr);
      if (IsInZygoteExecSpace(code_ptr) || GetLiveBitmap()->Test(allocation)) {
        ++it;
      } else {
        OatQuickMethodHeader* header = OatQuickMethodHeader::FromCodePointer(code_ptr);
        method_headers.insert(header);
        VLOG(jit) << "JIT removed " << it->second->PrettyMethod() << ": " << it->first;
        it = method_code_map_.erase(it);
      }
    }
    FreeAllMethodHeaders(method_headers);
  }
}

bool JitCodeCache::GetGarbageCollectCode() {
  MutexLock mu(Thread::Current(), *Locks::jit_lock_);
  return garbage_collect_code_;
}

void JitCodeCache::SetGarbageCollectCode(bool value) {
  Thread* self = Thread::Current();
  MutexLock mu(self, *Locks::jit_lock_);
  // Update the flag while holding the lock to ensure no thread will try to GC.
  garbage_collect_code_ = value;
}

ProfilingInfo* JitCodeCache::GetProfilingInfo(ArtMethod* method, Thread* self) {
  ScopedDebugDisallowReadBarriers sddrb(self);
  MutexLock mu(self, *Locks::jit_lock_);
  auto it = profiling_infos_.find(method);
  if (it == profiling_infos_.end()) {
    return nullptr;
  }
  return it->second;
}

void JitCodeCache::MaybeUpdateInlineCache(ArtMethod* method,
                                          uint32_t dex_pc,
                                          ObjPtr<mirror::Class> cls,
                                          Thread* self) {
  ScopedDebugDisallowReadBarriers sddrb(self);
  MutexLock mu(self, *Locks::jit_lock_);
  auto it = profiling_infos_.find(method);
  if (it == profiling_infos_.end()) {
    return;
  }
  ProfilingInfo* info = it->second;
  ScopedAssertNoThreadSuspension sants("ProfilingInfo");
  info->AddInvokeInfo(dex_pc, cls.Ptr());
}

void JitCodeCache::ResetHotnessCounter(ArtMethod* method, Thread* self) {
  ScopedDebugDisallowReadBarriers sddrb(self);
  MutexLock mu(self, *Locks::jit_lock_);
  auto it = profiling_infos_.find(method);
  DCHECK(it != profiling_infos_.end());
  it->second->ResetCounter();
}


void JitCodeCache::DoCollection(Thread* self) {
  ScopedTrace trace(__FUNCTION__);
  {
    ScopedDebugDisallowReadBarriers sddrb(self);
    MutexLock mu(self, *Locks::jit_lock_);
    // Mark compiled code that are entrypoints of ArtMethods. Compiled code that is not
    // an entry point is either:
    // - an osr compiled code, that will be removed if not in a thread call stack.
    // - discarded compiled code, that will be removed if not in a thread call stack.
    for (const auto& entry : jni_stubs_map_) {
      const JniStubData& data = entry.second;
      const void* code_ptr = data.GetCode();
      if (IsInZygoteExecSpace(code_ptr)) {
        continue;
      }
      const OatQuickMethodHeader* method_header = OatQuickMethodHeader::FromCodePointer(code_ptr);
      for (ArtMethod* method : data.GetMethods()) {
        if (method_header->GetEntryPoint() == method->GetEntryPointFromQuickCompiledCode()) {
          GetLiveBitmap()->AtomicTestAndSet(FromCodeToAllocation(code_ptr));
          break;
        }
      }
    }
    for (const auto& it : method_code_map_) {
      ArtMethod* method = it.second;
      const void* code_ptr = it.first;
      if (IsInZygoteExecSpace(code_ptr)) {
        continue;
      }
      const OatQuickMethodHeader* method_header = OatQuickMethodHeader::FromCodePointer(code_ptr);
      if (method_header->GetEntryPoint() == method->GetEntryPointFromQuickCompiledCode()) {
        GetLiveBitmap()->AtomicTestAndSet(FromCodeToAllocation(code_ptr));
      }
    }

    // Empty osr method map, as osr compiled code will be deleted (except the ones
    // on thread stacks).
    osr_code_map_.clear();
  }

  // Run a checkpoint on all threads to mark the JIT compiled code they are running.
  MarkCompiledCodeOnThreadStacks(self);

  // At this point, mutator threads are still running, and entrypoints of methods can
  // change. We do know they cannot change to a code cache entry that is not marked,
  // therefore we can safely remove those entries.
  RemoveUnmarkedCode(self);
}

OatQuickMethodHeader* JitCodeCache::LookupMethodHeader(uintptr_t pc, ArtMethod* method) {
  static_assert(kRuntimeISA != InstructionSet::kThumb2, "kThumb2 cannot be a runtime ISA");
  const void* pc_ptr = reinterpret_cast<const void*>(pc);
  if (!ContainsPc(pc_ptr)) {
    return nullptr;
  }

  if (!kIsDebugBuild) {
    // Called with null `method` only from MarkCodeClosure::Run() in debug build.
    CHECK(method != nullptr);
  }

  Thread* self = Thread::Current();
  ScopedDebugDisallowReadBarriers sddrb(self);
  MutexLock mu(self, *Locks::jit_lock_);
  OatQuickMethodHeader* method_header = nullptr;
  ArtMethod* found_method = nullptr;  // Only for DCHECK(), not for JNI stubs.
  if (method != nullptr && UNLIKELY(method->IsNative())) {
    auto it = jni_stubs_map_.find(JniStubKey(method));
    if (it == jni_stubs_map_.end()) {
      return nullptr;
    }
    if (!ContainsElement(it->second.GetMethods(), method)) {
      DCHECK(!OatQuickMethodHeader::FromCodePointer(it->second.GetCode())->Contains(pc))
          << "Method missing from stub map, but pc executing the method points to the stub."
          << " method= " << method->PrettyMethod()
          << " pc= " << std::hex << pc;
      return nullptr;
    }
    const void* code_ptr = it->second.GetCode();
    method_header = OatQuickMethodHeader::FromCodePointer(code_ptr);
    if (!method_header->Contains(pc)) {
      return nullptr;
    }
  } else {
    if (shared_region_.IsInExecSpace(pc_ptr)) {
      const void* code_ptr = zygote_map_.GetCodeFor(method, pc);
      if (code_ptr != nullptr) {
        return OatQuickMethodHeader::FromCodePointer(code_ptr);
      }
    }
    auto it = method_code_map_.lower_bound(pc_ptr);
    if ((it == method_code_map_.end() || it->first != pc_ptr) &&
        it != method_code_map_.begin()) {
      --it;
    }
    if (it != method_code_map_.end()) {
      const void* code_ptr = it->first;
      if (OatQuickMethodHeader::FromCodePointer(code_ptr)->Contains(pc)) {
        method_header = OatQuickMethodHeader::FromCodePointer(code_ptr);
        found_method = it->second;
      }
    }
    if (method_header == nullptr && method == nullptr) {
      // Scan all compiled JNI stubs as well. This slow search is used only
      // for checks in debug build, for release builds the `method` is not null.
      for (auto&& entry : jni_stubs_map_) {
        const JniStubData& data = entry.second;
        if (data.IsCompiled() &&
            OatQuickMethodHeader::FromCodePointer(data.GetCode())->Contains(pc)) {
          method_header = OatQuickMethodHeader::FromCodePointer(data.GetCode());
        }
      }
    }
    if (method_header == nullptr) {
      return nullptr;
    }
  }

  if (kIsDebugBuild && method != nullptr && !method->IsNative()) {
    DCHECK_EQ(found_method, method)
        << ArtMethod::PrettyMethod(method) << " "
        << ArtMethod::PrettyMethod(found_method) << " "
        << std::hex << pc;
  }
  return method_header;
}

OatQuickMethodHeader* JitCodeCache::LookupOsrMethodHeader(ArtMethod* method) {
  Thread* self = Thread::Current();
  ScopedDebugDisallowReadBarriers sddrb(self);
  MutexLock mu(self, *Locks::jit_lock_);
  auto it = osr_code_map_.find(method);
  if (it == osr_code_map_.end()) {
    return nullptr;
  }
  return OatQuickMethodHeader::FromCodePointer(it->second);
}

ProfilingInfo* JitCodeCache::AddProfilingInfo(Thread* self,
                                              ArtMethod* method,
                                              const std::vector<uint32_t>& inline_cache_entries,
                                              const std::vector<uint32_t>& branch_cache_entries) {
  DCHECK(CanAllocateProfilingInfo());
  ProfilingInfo* info = nullptr;
  {
    MutexLock mu(self, *Locks::jit_lock_);
    info = AddProfilingInfoInternal(self, method, inline_cache_entries, branch_cache_entries);
  }

  if (info == nullptr) {
    GarbageCollectCache(self);
    MutexLock mu(self, *Locks::jit_lock_);
    info = AddProfilingInfoInternal(self, method, inline_cache_entries, branch_cache_entries);
  }
  return info;
}

ProfilingInfo* JitCodeCache::AddProfilingInfoInternal(
    Thread* self,
    ArtMethod* method,
    const std::vector<uint32_t>& inline_cache_entries,
    const std::vector<uint32_t>& branch_cache_entries) {
  ScopedDebugDisallowReadBarriers sddrb(self);
  // Check whether some other thread has concurrently created it.
  auto it = profiling_infos_.find(method);
  if (it != profiling_infos_.end()) {
    return it->second;
  }

  size_t profile_info_size =
      ProfilingInfo::ComputeSize(inline_cache_entries.size(), branch_cache_entries.size());

  const uint8_t* data = private_region_.AllocateData(profile_info_size);
  if (data == nullptr) {
    return nullptr;
  }
  uint8_t* writable_data = private_region_.GetWritableDataAddress(data);
  ProfilingInfo* info =
      new (writable_data) ProfilingInfo(method, inline_cache_entries, branch_cache_entries);

  profiling_infos_.Put(method, info);
  histogram_profiling_info_memory_use_.AddValue(profile_info_size);
  return info;
}

void* JitCodeCache::MoreCore(const void* mspace, intptr_t increment) {
  return shared_region_.OwnsSpace(mspace)
      ? shared_region_.MoreCore(mspace, increment)
      : private_region_.MoreCore(mspace, increment);
}

void JitCodeCache::GetProfiledMethods(const std::set<std::string>& dex_base_locations,
                                      std::vector<ProfileMethodInfo>& methods,
                                      uint16_t inline_cache_threshold) {
  ScopedTrace trace(__FUNCTION__);
  Thread* self = Thread::Current();

  // Preserve class loaders to prevent unloading while we're processing
  // ArtMethods.
  VariableSizedHandleScope handles(self);
  Runtime::Current()->GetClassLinker()->GetClassLoaders(self, &handles);

  // Wait for any GC to be complete, to prevent looking at ArtMethods whose
  // class loader is being deleted.
  Runtime::Current()->GetHeap()->WaitForGcToComplete(gc::kGcCauseProfileSaver, self);

  // We'll be looking at inline caches, so ensure they are accessible.
  WaitUntilInlineCacheAccessible(self);

  SafeMap<ArtMethod*, ProfilingInfo*> profiling_infos;
  std::vector<ArtMethod*> copies;
  {
    MutexLock mu(self, *Locks::jit_lock_);
    profiling_infos = profiling_infos_;
    for (const auto& entry : method_code_map_) {
      copies.push_back(entry.second);
    }
  }
  for (ArtMethod* method : copies) {
    auto it = profiling_infos.find(method);
    ProfilingInfo* info = (it == profiling_infos.end()) ? nullptr : it->second;
    const DexFile* dex_file = method->GetDexFile();
    const std::string base_location = DexFileLoader::GetBaseLocation(dex_file->GetLocation());
    if (!ContainsElement(dex_base_locations, base_location)) {
      // Skip dex files which are not profiled.
      continue;
    }
    std::vector<ProfileMethodInfo::ProfileInlineCache> inline_caches;

    if (info != nullptr) {
      // If the method is still baseline compiled and doesn't meet the inline cache threshold, don't
      // save the inline caches because they might be incomplete.
      // Although we don't deoptimize for incomplete inline caches in AOT-compiled code, inlining
      // leads to larger generated code.
      // If the inline cache is empty the compiler will generate a regular invoke virtual/interface.
      const void* entry_point = method->GetEntryPointFromQuickCompiledCode();
      if (ContainsPc(entry_point) &&
          CodeInfo::IsBaseline(
              OatQuickMethodHeader::FromEntryPoint(entry_point)->GetOptimizedCodeInfoPtr()) &&
          (ProfilingInfo::GetOptimizeThreshold() - info->GetBaselineHotnessCount()) <
              inline_cache_threshold) {
        methods.emplace_back(/*ProfileMethodInfo*/
            MethodReference(dex_file, method->GetDexMethodIndex()), inline_caches);
        continue;
      }

      for (size_t i = 0; i < info->number_of_inline_caches_; ++i) {
        std::vector<TypeReference> profile_classes;
        const InlineCache& cache = info->GetInlineCaches()[i];
        ArtMethod* caller = info->GetMethod();
        bool is_missing_types = false;
        for (size_t k = 0; k < InlineCache::kIndividualCacheSize; k++) {
          mirror::Class* cls = cache.classes_[k].Read();
          if (cls == nullptr) {
            break;
          }

          // Check if the receiver is in the boot class path or if it's in the
          // same class loader as the caller. If not, skip it, as there is not
          // much we can do during AOT.
          if (!cls->IsBootStrapClassLoaded() &&
              caller->GetClassLoader() != cls->GetClassLoader()) {
            is_missing_types = true;
            continue;
          }

          const DexFile* class_dex_file = nullptr;
          dex::TypeIndex type_index;

          if (cls->GetDexCache() == nullptr) {
            DCHECK(cls->IsArrayClass()) << cls->PrettyClass();
            // Make a best effort to find the type index in the method's dex file.
            // We could search all open dex files but that might turn expensive
            // and probably not worth it.
            class_dex_file = dex_file;
            type_index = cls->FindTypeIndexInOtherDexFile(*dex_file);
          } else {
            class_dex_file = &(cls->GetDexFile());
            type_index = cls->GetDexTypeIndex();
          }
          if (!type_index.IsValid()) {
            // Could be a proxy class or an array for which we couldn't find the type index.
            is_missing_types = true;
            continue;
          }
          if (ContainsElement(dex_base_locations,
                              DexFileLoader::GetBaseLocation(class_dex_file->GetLocation()))) {
            // Only consider classes from the same apk (including multidex).
            profile_classes.emplace_back(/*ProfileMethodInfo::ProfileClassReference*/
                class_dex_file, type_index);
          } else {
            is_missing_types = true;
          }
        }
        if (!profile_classes.empty()) {
          inline_caches.emplace_back(/*ProfileMethodInfo::ProfileInlineCache*/
              cache.dex_pc_, is_missing_types, profile_classes);
        }
      }
    }
    methods.emplace_back(/*ProfileMethodInfo*/
        MethodReference(dex_file, method->GetDexMethodIndex()), inline_caches);
  }
}

bool JitCodeCache::IsOsrCompiled(ArtMethod* method) {
  Thread* self = Thread::Current();
  ScopedDebugDisallowReadBarriers sddrb(self);
  MutexLock mu(self, *Locks::jit_lock_);
  return osr_code_map_.find(method) != osr_code_map_.end();
}

bool JitCodeCache::NotifyCompilationOf(ArtMethod* method,
                                       Thread* self,
                                       CompilationKind compilation_kind,
                                       bool prejit) {
  const void* existing_entry_point = method->GetEntryPointFromQuickCompiledCode();
  if (compilation_kind == CompilationKind::kBaseline && ContainsPc(existing_entry_point)) {
    // The existing entry point is either already baseline, or optimized. No
    // need to compile.
    VLOG(jit) << "Not compiling "
              << method->PrettyMethod()
              << " baseline, because it has already been compiled";
    return false;
  }

  if (method->NeedsClinitCheckBeforeCall() && !prejit) {
    // We do not need a synchronization barrier for checking the visibly initialized status
    // or checking the initialized status just for requesting visible initialization.
    ClassStatus status = method->GetDeclaringClass()
        ->GetStatus<kDefaultVerifyFlags, /*kWithSynchronizationBarrier=*/ false>();
    if (status != ClassStatus::kVisiblyInitialized) {
      // Unless we're pre-jitting, we currently don't save the JIT compiled code if we cannot
      // update the entrypoint due to needing an initialization check.
      if (status == ClassStatus::kInitialized) {
        // Request visible initialization but do not block to allow compiling other methods.
        // Hopefully, this will complete by the time the method becomes hot again.
        Runtime::Current()->GetClassLinker()->MakeInitializedClassesVisiblyInitialized(
            self, /*wait=*/ false);
      }
      VLOG(jit) << "Not compiling "
                << method->PrettyMethod()
                << " because it has the resolution stub";
      // Give it a new chance to be hot.
      ClearMethodCounter(method, /*was_warm=*/ false);
      return false;
    }
  }

  ScopedDebugDisallowReadBarriers sddrb(self);
  if (compilation_kind == CompilationKind::kOsr) {
    MutexLock mu(self, *Locks::jit_lock_);
    if (osr_code_map_.find(method) != osr_code_map_.end()) {
      return false;
    }
  }

  if (UNLIKELY(method->IsNative())) {
    MutexLock mu(self, *Locks::jit_lock_);
    JniStubKey key(method);
    auto it = jni_stubs_map_.find(key);
    bool new_compilation = false;
    if (it == jni_stubs_map_.end()) {
      // Create a new entry to mark the stub as being compiled.
      it = jni_stubs_map_.Put(key, JniStubData{});
      new_compilation = true;
    }
    JniStubData* data = &it->second;
    data->AddMethod(method);
    if (data->IsCompiled()) {
      OatQuickMethodHeader* method_header = OatQuickMethodHeader::FromCodePointer(data->GetCode());
      const void* entrypoint = method_header->GetEntryPoint();
      // Update also entrypoints of other methods held by the JniStubData.
      // We could simply update the entrypoint of `method` but if the last JIT GC has
      // changed these entrypoints to GenericJNI in preparation for a full GC, we may
      // as well change them back as this stub shall not be collected anyway and this
      // can avoid a few expensive GenericJNI calls.
      data->UpdateEntryPoints(entrypoint);
      if (collection_in_progress_) {
        if (!IsInZygoteExecSpace(data->GetCode())) {
          GetLiveBitmap()->AtomicTestAndSet(FromCodeToAllocation(data->GetCode()));
        }
      }
    }
    return new_compilation;
  } else {
    if (compilation_kind == CompilationKind::kBaseline) {
      DCHECK(CanAllocateProfilingInfo());
    }
  }
  return true;
}

ProfilingInfo* JitCodeCache::NotifyCompilerUse(ArtMethod* method, Thread* self) {
  ScopedDebugDisallowReadBarriers sddrb(self);
  MutexLock mu(self, *Locks::jit_lock_);
  auto it = profiling_infos_.find(method);
  if (it == profiling_infos_.end()) {
    return nullptr;
  }
  if (!it->second->IncrementInlineUse()) {
    // Overflow of inlining uses, just bail.
    return nullptr;
  }
  return it->second;
}

void JitCodeCache::DoneCompilerUse(ArtMethod* method, Thread* self) {
  ScopedDebugDisallowReadBarriers sddrb(self);
  MutexLock mu(self, *Locks::jit_lock_);
  auto it = profiling_infos_.find(method);
  DCHECK(it != profiling_infos_.end());
  it->second->DecrementInlineUse();
}

void JitCodeCache::DoneCompiling(ArtMethod* method, Thread* self) {
  DCHECK_EQ(Thread::Current(), self);
  ScopedDebugDisallowReadBarriers sddrb(self);
  MutexLock mu(self, *Locks::jit_lock_);
  if (UNLIKELY(method->IsNative())) {
    auto it = jni_stubs_map_.find(JniStubKey(method));
    DCHECK(it != jni_stubs_map_.end());
    JniStubData* data = &it->second;
    DCHECK(ContainsElement(data->GetMethods(), method));
    if (UNLIKELY(!data->IsCompiled())) {
      // Failed to compile; the JNI compiler never fails, but the cache may be full.
      jni_stubs_map_.erase(it);  // Remove the entry added in NotifyCompilationOf().
    }  // else Commit() updated entrypoints of all methods in the JniStubData.
  }
}

void JitCodeCache::InvalidateAllCompiledCode() {
  Thread* self = Thread::Current();
  ScopedDebugDisallowReadBarriers sddrb(self);
  art::MutexLock mu(self, *Locks::jit_lock_);
  VLOG(jit) << "Invalidating all compiled code";
  Runtime* runtime = Runtime::Current();
  ClassLinker* linker = runtime->GetClassLinker();
  instrumentation::Instrumentation* instr = runtime->GetInstrumentation();

  // Change entry points of native methods back to the GenericJNI entrypoint.
  for (const auto& entry : jni_stubs_map_) {
    const JniStubData& data = entry.second;
    if (!data.IsCompiled() || IsInZygoteExecSpace(data.GetCode())) {
      continue;
    }
    const OatQuickMethodHeader* method_header =
        OatQuickMethodHeader::FromCodePointer(data.GetCode());
    for (ArtMethod* method : data.GetMethods()) {
      if (method->GetEntryPointFromQuickCompiledCode() == method_header->GetEntryPoint()) {
        ClearMethodCounter(method, /*was_warm=*/true);
        instr->InitializeMethodsCode(method, /*aot_code=*/ nullptr);
      }
    }
  }
  for (const auto& entry : method_code_map_) {
    ArtMethod* meth = entry.second;
    // We were compiled, so we must be warm.
    ClearMethodCounter(meth, /*was_warm=*/true);
    if (UNLIKELY(meth->IsObsolete())) {
      linker->SetEntryPointsForObsoleteMethod(meth);
    } else {
      instr->InitializeMethodsCode(meth, /*aot_code=*/ nullptr);
    }
  }

  for (const auto& entry : zygote_map_) {
    if (entry.method == nullptr) {
      continue;
    }
    if (entry.method->IsPreCompiled()) {
      entry.method->ClearPreCompiled();
    }
    instr->InitializeMethodsCode(entry.method, /*aot_code=*/nullptr);
  }

  saved_compiled_methods_map_.clear();
  osr_code_map_.clear();
}

void JitCodeCache::InvalidateCompiledCodeFor(ArtMethod* method,
                                             const OatQuickMethodHeader* header) {
  DCHECK(!method->IsNative());
  const void* method_entrypoint = method->GetEntryPointFromQuickCompiledCode();

  // Clear the method counter if we are running jitted code since we might want to jit this again in
  // the future.
  if (method_entrypoint == header->GetEntryPoint()) {
    // The entrypoint is the one to invalidate, so we just update it to the interpreter entry point
    // and clear the counter to get the method Jitted again.
    Runtime::Current()->GetInstrumentation()->InitializeMethodsCode(method, /*aot_code=*/ nullptr);
    ClearMethodCounter(method, /*was_warm=*/ true);
  } else {
    Thread* self = Thread::Current();
    ScopedDebugDisallowReadBarriers sddrb(self);
    MutexLock mu(self, *Locks::jit_lock_);
    auto it = osr_code_map_.find(method);
    if (it != osr_code_map_.end() && OatQuickMethodHeader::FromCodePointer(it->second) == header) {
      // Remove the OSR method, to avoid using it again.
      osr_code_map_.erase(it);
    }
  }

  // In case the method was pre-compiled, clear that information so we
  // can recompile it ourselves.
  if (method->IsPreCompiled()) {
    method->ClearPreCompiled();
  }
}

void JitCodeCache::Dump(std::ostream& os) {
  MutexLock mu(Thread::Current(), *Locks::jit_lock_);
  os << "Current JIT code cache size (used / resident): "
     << GetCurrentRegion()->GetUsedMemoryForCode() / KB << "KB / "
     << GetCurrentRegion()->GetResidentMemoryForCode() / KB << "KB\n"
     << "Current JIT data cache size (used / resident): "
     << GetCurrentRegion()->GetUsedMemoryForData() / KB << "KB / "
     << GetCurrentRegion()->GetResidentMemoryForData() / KB << "KB\n";
  if (!Runtime::Current()->IsZygote()) {
    os << "Zygote JIT code cache size (at point of fork): "
       << shared_region_.GetUsedMemoryForCode() / KB << "KB / "
       << shared_region_.GetResidentMemoryForCode() / KB << "KB\n"
       << "Zygote JIT data cache size (at point of fork): "
       << shared_region_.GetUsedMemoryForData() / KB << "KB / "
       << shared_region_.GetResidentMemoryForData() / KB << "KB\n";
  }
  os << "Current JIT mini-debug-info size: " << PrettySize(GetJitMiniDebugInfoMemUsage()) << "\n"
     << "Current JIT capacity: " << PrettySize(GetCurrentRegion()->GetCurrentCapacity()) << "\n"
     << "Current number of JIT JNI stub entries: " << jni_stubs_map_.size() << "\n"
     << "Current number of JIT code cache entries: " << method_code_map_.size() << "\n"
     << "Total number of JIT baseline compilations: " << number_of_baseline_compilations_ << "\n"
     << "Total number of JIT optimized compilations: " << number_of_optimized_compilations_ << "\n"
     << "Total number of JIT compilations for on stack replacement: "
        << number_of_osr_compilations_ << "\n"
     << "Total number of JIT code cache collections: " << number_of_collections_ << std::endl;
  histogram_stack_map_memory_use_.PrintMemoryUse(os);
  histogram_code_memory_use_.PrintMemoryUse(os);
  histogram_profiling_info_memory_use_.PrintMemoryUse(os);
}

void JitCodeCache::DumpAllCompiledMethods(std::ostream& os) {
  MutexLock mu(Thread::Current(), *Locks::jit_lock_);
  for (auto it : method_code_map_) {  // Includes OSR methods.
    ArtMethod* meth = it.second;
    const void* code_ptr = it.first;
    OatQuickMethodHeader* header = OatQuickMethodHeader::FromCodePointer(code_ptr);
    os << meth->PrettyMethod() << "@"  << std::hex
       << code_ptr << "-" << reinterpret_cast<uintptr_t>(code_ptr) + header->GetCodeSize() << '\n';
  }
  os << "JNIStubs: \n";
  for (auto it : jni_stubs_map_) {
    const void* code_ptr = it.second.GetCode();
    if (code_ptr == nullptr) {
      continue;
    }
    OatQuickMethodHeader* header = OatQuickMethodHeader::FromCodePointer(code_ptr);
    os << std::hex << code_ptr << "-"
       << reinterpret_cast<uintptr_t>(code_ptr) + header->GetCodeSize() << " ";
    for (ArtMethod* m : it.second.GetMethods()) {
      os << m->PrettyMethod() << ";";
    }
    os << "\n";
  }
}

void JitCodeCache::PostForkChildAction(bool is_system_server, bool is_zygote) {
  Thread* self = Thread::Current();

  // Remove potential tasks that have been inherited from the zygote.
  // We do this now and not in Jit::PostForkChildAction, as system server calls
  // JitCodeCache::PostForkChildAction first, and then does some code loading
  // that may result in new JIT tasks that we want to keep.
  Runtime* runtime = Runtime::Current();
  JitThreadPool* pool = runtime->GetJit()->GetThreadPool();
  if (pool != nullptr) {
    pool->RemoveAllTasks(self);
  }

  MutexLock mu(self, *Locks::jit_lock_);

  // Reset potential writable MemMaps inherited from the zygote. We never want
  // to write to them.
  shared_region_.ResetWritableMappings();

  if (is_zygote || runtime->IsSafeMode()) {
    // Don't create a private region for a child zygote. Regions are usually map shared
    // (to satisfy dual-view), and we don't want children of a child zygote to inherit it.
    return;
  }

  // Reset all statistics to be specific to this process.
  number_of_baseline_compilations_ = 0;
  number_of_optimized_compilations_ = 0;
  number_of_osr_compilations_ = 0;
  number_of_collections_ = 0;
  histogram_stack_map_memory_use_.Reset();
  histogram_code_memory_use_.Reset();
  histogram_profiling_info_memory_use_.Reset();

  size_t initial_capacity = runtime->GetJITOptions()->GetCodeCacheInitialCapacity();
  size_t max_capacity = runtime->GetJITOptions()->GetCodeCacheMaxCapacity();
  std::string error_msg;
  if (!private_region_.Initialize(initial_capacity,
                                  max_capacity,
                                  /* rwx_memory_allowed= */ !is_system_server,
                                  is_zygote,
                                  &error_msg)) {
    LOG(FATAL) << "Could not create private region after zygote fork: " << error_msg;
  }
  if (private_region_.HasCodeMapping()) {
    const MemMap* exec_pages = private_region_.GetExecPages();
    runtime->AddGeneratedCodeRange(exec_pages->Begin(), exec_pages->Size());
  }
}

JitMemoryRegion* JitCodeCache::GetCurrentRegion() {
  return Runtime::Current()->IsZygote() ? &shared_region_ : &private_region_;
}

void JitCodeCache::VisitAllMethods(const std::function<void(const void*, ArtMethod*)>& cb) {
  for (const auto& it : jni_stubs_map_) {
    const JniStubData& data = it.second;
    if (data.IsCompiled()) {
      for (ArtMethod* method : data.GetMethods()) {
        cb(data.GetCode(), method);
      }
    }
  }
  for (auto it : method_code_map_) {  // Includes OSR methods.
    cb(it.first, it.second);
  }
  for (auto it : saved_compiled_methods_map_) {
    cb(it.second, it.first);
  }
  for (auto it : zygote_map_) {
    if (it.code_ptr != nullptr && it.method != nullptr) {
      cb(it.code_ptr, it.method);
    }
  }
}

void ZygoteMap::Initialize(uint32_t number_of_methods) {
  MutexLock mu(Thread::Current(), *Locks::jit_lock_);
  // Allocate for 40-80% capacity. This will offer OK lookup times, and termination
  // cases.
  size_t capacity = RoundUpToPowerOfTwo(number_of_methods * 100 / 80);
  const uint8_t* memory = region_->AllocateData(
      capacity * sizeof(Entry) + sizeof(ZygoteCompilationState));
  if (memory == nullptr) {
    LOG(WARNING) << "Could not allocate data for the zygote map";
    return;
  }
  const Entry* data = reinterpret_cast<const Entry*>(memory);
  region_->FillData(data, capacity, Entry { nullptr, nullptr });
  map_ = ArrayRef(data, capacity);
  compilation_state_ = reinterpret_cast<const ZygoteCompilationState*>(
      memory + capacity * sizeof(Entry));
  region_->WriteData(compilation_state_, ZygoteCompilationState::kInProgress);
}

const void* ZygoteMap::GetCodeFor(ArtMethod* method, uintptr_t pc) const {
  if (map_.empty()) {
    return nullptr;
  }

  if (method == nullptr) {
    // Do a linear search. This should only be used in debug builds.
    CHECK(kIsDebugBuild);
    for (const Entry& entry : map_) {
      const void* code_ptr = entry.code_ptr;
      if (code_ptr != nullptr) {
        OatQuickMethodHeader* method_header = OatQuickMethodHeader::FromCodePointer(code_ptr);
        if (method_header->Contains(pc)) {
          return code_ptr;
        }
      }
    }
    return nullptr;
  }

  std::hash<ArtMethod*> hf;
  size_t index = hf(method) & (map_.size() - 1u);
  size_t original_index = index;
  // Loop over the array: we know this loop terminates as we will either
  // encounter the given method, or a null entry. Both terminate the loop.
  // Note that the zygote may concurrently write new entries to the map. That's OK as the
  // map is never resized.
  while (true) {
    const Entry& entry = map_[index];
    if (entry.method == nullptr) {
      // Not compiled yet.
      return nullptr;
    }
    if (entry.method == method) {
      if (entry.code_ptr == nullptr) {
        // This is a race with the zygote which wrote the method, but hasn't written the
        // code. Just bail and wait for the next time we need the method.
        return nullptr;
      }
      if (pc != 0 && !OatQuickMethodHeader::FromCodePointer(entry.code_ptr)->Contains(pc)) {
        return nullptr;
      }
      return entry.code_ptr;
    }
    index = (index + 1) & (map_.size() - 1);
    DCHECK_NE(original_index, index);
  }
}

void ZygoteMap::Put(const void* code, ArtMethod* method) {
  if (map_.empty()) {
    return;
  }
  CHECK(Runtime::Current()->IsZygote());
  std::hash<ArtMethod*> hf;
  size_t index = hf(method) & (map_.size() - 1);
  size_t original_index = index;
  // Because the size of the map is bigger than the number of methods that will
  // be added, we are guaranteed to find a free slot in the array, and
  // therefore for this loop to terminate.
  while (true) {
    const Entry* entry = &map_[index];
    if (entry->method == nullptr) {
      // Note that readers can read this memory concurrently, but that's OK as
      // we are writing pointers.
      region_->WriteData(entry, Entry { method, code });
      break;
    }
    index = (index + 1) & (map_.size() - 1);
    DCHECK_NE(original_index, index);
  }
  DCHECK_EQ(GetCodeFor(method), code);
}

}  // namespace jit
}  // namespace art