blob: e235bc45530401c6861de1f54df816b7f67814ff [file] [log] [blame]
* 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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include <stdint.h>
#include "base/memory_tool.h"
#include <cstddef>
#include <memory>
#include <set>
#include <string>
#include <ostream>
#include "base/bit_utils.h"
#include "base/macros.h"
#include "driver/compiler_driver.h"
#include "gc/space/space.h"
#include "length_prefixed_array.h"
#include "lock_word.h"
#include "mem_map.h"
#include "oat_file.h"
#include "mirror/dex_cache.h"
#include "os.h"
#include "safe_map.h"
#include "utils.h"
namespace art {
// Write a Space built during compilation for use during execution.
class ImageWriter FINAL {
ImageWriter(const CompilerDriver& compiler_driver, uintptr_t image_begin,
bool compile_pic)
: compiler_driver_(compiler_driver), image_begin_(reinterpret_cast<uint8_t*>(image_begin)),
image_end_(0), image_objects_offset_begin_(0), image_roots_address_(0), oat_file_(nullptr),
oat_data_begin_(nullptr), interpreter_to_interpreter_bridge_offset_(0),
interpreter_to_compiled_code_bridge_offset_(0), jni_dlsym_lookup_offset_(0),
quick_imt_conflict_trampoline_offset_(0), quick_resolution_trampoline_offset_(0),
quick_to_interpreter_bridge_offset_(0), compile_pic_(compile_pic),
bin_slot_sizes_(), bin_slot_offsets_(), bin_slot_count_(),
intern_table_bytes_(0u), image_method_array_(ImageHeader::kImageMethodsCount),
dirty_methods_(0u), clean_methods_(0u) {
CHECK_NE(image_begin, 0U);
std::fill(image_methods_, image_methods_ + arraysize(image_methods_), nullptr);
~ImageWriter() {
bool PrepareImageAddressSpace();
bool IsImageAddressSpaceReady() const {
return image_roots_address_ != 0u;
template <typename T>
T* GetImageAddress(T* object) const SHARED_REQUIRES(Locks::mutator_lock_) {
return object == nullptr ? nullptr :
reinterpret_cast<T*>(image_begin_ + GetImageOffset(object));
ArtMethod* GetImageMethodAddress(ArtMethod* method) SHARED_REQUIRES(Locks::mutator_lock_);
template <typename PtrType>
PtrType GetDexCacheArrayElementImageAddress(const DexFile* dex_file, uint32_t offset)
const SHARED_REQUIRES(Locks::mutator_lock_) {
auto it = dex_cache_array_starts_.find(dex_file);
DCHECK(it != dex_cache_array_starts_.end());
return reinterpret_cast<PtrType>(
image_begin_ + bin_slot_offsets_[kBinDexCacheArray] + it->second + offset);
uint8_t* GetOatFileBegin() const;
bool Write(const std::string& image_filename, const std::string& oat_filename,
const std::string& oat_location)
uintptr_t GetOatDataBegin() {
return reinterpret_cast<uintptr_t>(oat_data_begin_);
bool AllocMemory();
// Mark the objects defined in this space in the given live bitmap.
void RecordImageAllocations() SHARED_REQUIRES(Locks::mutator_lock_);
// Classify different kinds of bins that objects end up getting packed into during image writing.
enum Bin {
// Likely-clean:
kBinString, // [String] Almost always immutable (except for obj header).
// Unknown mix of clean/dirty:
// Likely-dirty:
// All classes get their own bins since their fields often dirty
kBinClassInitializedFinalStatics, // Class initializers have been run, no non-final statics
kBinClassInitialized, // Class initializers have been run
kBinClassVerified, // Class verified, but initializers haven't been run
// Add more bins here if we add more segregation code.
// Non mirror fields must be below.
// ArtFields should be always clean.
// If the class is initialized, then the ArtMethods are probably clean.
// ArtMethods may be dirty if the class has native methods or a declaring class that isn't
// initialized.
// Dex cache arrays have a special slot for PC-relative addressing. Since they are
// huge, and as such their dirtiness is not important for the clean/dirty separation,
// we arbitrarily keep them at the end of the native data.
kBinDexCacheArray, // Arrays belonging to dex cache.
// Number of bins which are for mirror objects.
kBinMirrorCount = kBinArtField,
friend std::ostream& operator<<(std::ostream& stream, const Bin& bin);
enum NativeObjectRelocationType {
friend std::ostream& operator<<(std::ostream& stream, const NativeObjectRelocationType& type);
static constexpr size_t kBinBits = MinimumBitsToStore<uint32_t>(kBinMirrorCount - 1);
// uint32 = typeof(lockword_)
// Subtract read barrier bits since we want these to remain 0, or else it may result in DCHECK
// failures due to invalid read barrier bits during object field reads.
static const size_t kBinShift = BitSizeOf<uint32_t>() - kBinBits -
// 111000.....0
static const size_t kBinMask = ((static_cast<size_t>(1) << kBinBits) - 1) << kBinShift;
// We use the lock word to store the bin # and bin index of the object in the image.
// The struct size must be exactly sizeof(LockWord), currently 32-bits, since this will end up
// stored in the lock word bit-for-bit when object forwarding addresses are being calculated.
struct BinSlot {
explicit BinSlot(uint32_t lockword);
BinSlot(Bin bin, uint32_t index);
// The bin an object belongs to, i.e. regular, class/verified, class/initialized, etc.
Bin GetBin() const;
// The offset in bytes from the beginning of the bin. Aligned to object size.
uint32_t GetIndex() const;
// Pack into a single uint32_t, for storing into a lock word.
uint32_t Uint32Value() const { return lockword_; }
// Comparison operator for map support
bool operator<(const BinSlot& other) const { return lockword_ < other.lockword_; }
// Must be the same size as LockWord, any larger and we would truncate the data.
const uint32_t lockword_;
// We use the lock word to store the offset of the object in the image.
void AssignImageOffset(mirror::Object* object, BinSlot bin_slot)
void SetImageOffset(mirror::Object* object, size_t offset)
bool IsImageOffsetAssigned(mirror::Object* object) const
size_t GetImageOffset(mirror::Object* object) const SHARED_REQUIRES(Locks::mutator_lock_);
void UpdateImageOffset(mirror::Object* obj, uintptr_t offset)
void PrepareDexCacheArraySlots() SHARED_REQUIRES(Locks::mutator_lock_);
void AssignImageBinSlot(mirror::Object* object) SHARED_REQUIRES(Locks::mutator_lock_);
void SetImageBinSlot(mirror::Object* object, BinSlot bin_slot)
bool IsImageBinSlotAssigned(mirror::Object* object) const
BinSlot GetImageBinSlot(mirror::Object* object) const SHARED_REQUIRES(Locks::mutator_lock_);
void AddDexCacheArrayRelocation(void* array, size_t offset) SHARED_REQUIRES(Locks::mutator_lock_);
void AddMethodPointerArray(mirror::PointerArray* arr) SHARED_REQUIRES(Locks::mutator_lock_);
static void* GetImageAddressCallback(void* writer, mirror::Object* obj)
SHARED_REQUIRES(Locks::mutator_lock_) {
return reinterpret_cast<ImageWriter*>(writer)->GetImageAddress(obj);
mirror::Object* GetLocalAddress(mirror::Object* object) const
SHARED_REQUIRES(Locks::mutator_lock_) {
size_t offset = GetImageOffset(object);
uint8_t* dst = image_->Begin() + offset;
return reinterpret_cast<mirror::Object*>(dst);
const uint8_t* GetOatAddress(uint32_t offset) const {
// With Quick, code is within the OatFile, as there are all in one
// .o ELF object.
DCHECK_LE(offset, oat_file_->Size());
DCHECK(oat_data_begin_ != nullptr);
return offset == 0u ? nullptr : oat_data_begin_ + offset;
// Returns true if the class was in the original requested image classes list.
bool IsImageClass(mirror::Class* klass) SHARED_REQUIRES(Locks::mutator_lock_);
// Debug aid that list of requested image classes.
void DumpImageClasses();
// Preinitializes some otherwise lazy fields (such as Class name) to avoid runtime image dirtying.
void ComputeLazyFieldsForImageClasses()
// Remove unwanted classes from various roots.
void PruneNonImageClasses() SHARED_REQUIRES(Locks::mutator_lock_);
// Verify unwanted classes removed.
void CheckNonImageClassesRemoved() SHARED_REQUIRES(Locks::mutator_lock_);
static void CheckNonImageClassesRemovedCallback(mirror::Object* obj, void* arg)
// Lays out where the image objects will be at runtime.
void CalculateNewObjectOffsets()
void CreateHeader(size_t oat_loaded_size, size_t oat_data_offset)
mirror::ObjectArray<mirror::Object>* CreateImageRoots() const
void CalculateObjectBinSlots(mirror::Object* obj)
void UnbinObjectsIntoOffset(mirror::Object* obj)
void WalkInstanceFields(mirror::Object* obj, mirror::Class* klass)
void WalkFieldsInOrder(mirror::Object* obj)
static void WalkFieldsCallback(mirror::Object* obj, void* arg)
static void UnbinObjectsIntoOffsetCallback(mirror::Object* obj, void* arg)
// Creates the contiguous image in memory and adjusts pointers.
void CopyAndFixupNativeData() SHARED_REQUIRES(Locks::mutator_lock_);
void CopyAndFixupObjects() SHARED_REQUIRES(Locks::mutator_lock_);
static void CopyAndFixupObjectsCallback(mirror::Object* obj, void* arg)
void CopyAndFixupObject(mirror::Object* obj) SHARED_REQUIRES(Locks::mutator_lock_);
void CopyAndFixupMethod(ArtMethod* orig, ArtMethod* copy)
void FixupClass(mirror::Class* orig, mirror::Class* copy)
void FixupObject(mirror::Object* orig, mirror::Object* copy)
void FixupDexCache(mirror::DexCache* orig_dex_cache, mirror::DexCache* copy_dex_cache)
void FixupPointerArray(mirror::Object* dst, mirror::PointerArray* arr, mirror::Class* klass,
Bin array_type) SHARED_REQUIRES(Locks::mutator_lock_);
// Get quick code for non-resolution/imt_conflict/abstract method.
const uint8_t* GetQuickCode(ArtMethod* method, bool* quick_is_interpreted)
const uint8_t* GetQuickEntryPoint(ArtMethod* method)
// Patches references in OatFile to expect runtime addresses.
void SetOatChecksumFromElfFile(File* elf_file);
// Calculate the sum total of the bin slot sizes in [0, up_to). Defaults to all bins.
size_t GetBinSizeSum(Bin up_to = kBinSize) const;
// Return true if a method is likely to be dirtied at runtime.
bool WillMethodBeDirty(ArtMethod* m) const SHARED_REQUIRES(Locks::mutator_lock_);
// Assign the offset for an ArtMethod.
void AssignMethodOffset(ArtMethod* method, NativeObjectRelocationType type)
static Bin BinTypeForNativeRelocationType(NativeObjectRelocationType type);
uintptr_t NativeOffsetInImage(void* obj);
template <typename T>
T* NativeLocationInImage(T* obj);
const CompilerDriver& compiler_driver_;
// Beginning target image address for the output image.
uint8_t* image_begin_;
// Offset to the free space in image_.
size_t image_end_;
// Offset from image_begin_ to where the first object is in image_.
size_t image_objects_offset_begin_;
// The image roots address in the image.
uint32_t image_roots_address_;
// oat file with code for this image
OatFile* oat_file_;
// Memory mapped for generating the image.
std::unique_ptr<MemMap> image_;
// Pointer arrays that need to be updated. Since these are only some int and long arrays, we need
// to keep track. These include vtable arrays, iftable arrays, and dex caches.
std::unordered_map<mirror::PointerArray*, Bin> pointer_arrays_;
// The start offsets of the dex cache arrays.
SafeMap<const DexFile*, size_t> dex_cache_array_starts_;
// Saved hash codes. We use these to restore lockwords which were temporarily used to have
// forwarding addresses as well as copying over hash codes.
std::unordered_map<mirror::Object*, uint32_t> saved_hashcode_map_;
// Beginning target oat address for the pointers from the output image to its oat file.
const uint8_t* oat_data_begin_;
// Image bitmap which lets us know where the objects inside of the image reside.
std::unique_ptr<gc::accounting::ContinuousSpaceBitmap> image_bitmap_;
// Offset from oat_data_begin_ to the stubs.
uint32_t interpreter_to_interpreter_bridge_offset_;
uint32_t interpreter_to_compiled_code_bridge_offset_;
uint32_t jni_dlsym_lookup_offset_;
uint32_t quick_generic_jni_trampoline_offset_;
uint32_t quick_imt_conflict_trampoline_offset_;
uint32_t quick_resolution_trampoline_offset_;
uint32_t quick_to_interpreter_bridge_offset_;
const bool compile_pic_;
// Size of pointers on the target architecture.
size_t target_ptr_size_;
// Bin slot tracking for dirty object packing
size_t bin_slot_sizes_[kBinSize]; // Number of bytes in a bin
size_t bin_slot_offsets_[kBinSize]; // Number of bytes in previous bins.
size_t bin_slot_count_[kBinSize]; // Number of objects in a bin
// Cached size of the intern table for when we allocate memory.
size_t intern_table_bytes_;
// ArtField, ArtMethod relocating map. These are allocated as array of structs but we want to
// have one entry per art field for convenience. ArtFields are placed right after the end of the
// image objects (aka sum of bin_slot_sizes_). ArtMethods are placed right after the ArtFields.
struct NativeObjectRelocation {
uintptr_t offset;
NativeObjectRelocationType type;
bool IsArtMethodRelocation() const {
return type == kNativeObjectRelocationTypeArtMethodClean ||
type == kNativeObjectRelocationTypeArtMethodDirty;
std::unordered_map<void*, NativeObjectRelocation> native_object_relocations_;
// Runtime ArtMethods which aren't reachable from any Class but need to be copied into the image.
ArtMethod* image_methods_[ImageHeader::kImageMethodsCount];
// Fake length prefixed array for image methods. This array does not contain the actual
// ArtMethods. We only use it for the header and relocation addresses.
LengthPrefixedArray<ArtMethod> image_method_array_;
// Counters for measurements, used for logging only.
uint64_t dirty_methods_;
uint64_t clean_methods_;
friend class FixupClassVisitor;
friend class FixupRootVisitor;
friend class FixupVisitor;
friend class NonImageClassesVisitor;
} // namespace art