blob: dba9dd71fc24e91fe46ceacadd67622f424418d2 [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/dchecked_vector.h"
#include "base/length_prefixed_array.h"
#include "base/macros.h"
#include "driver/compiler_driver.h"
#include "gc/space/space.h"
#include "image.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 {
namespace gc {
namespace space {
class ImageSpace;
} // namespace space
} // namespace gc
class ClassTable;
static constexpr int kInvalidFd = -1;
// 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,
bool compile_app_image,
ImageHeader::StorageMode image_storage_mode,
const std::vector<const char*>& oat_filenames,
const std::unordered_map<const DexFile*, size_t>& dex_file_oat_index_map);
bool PrepareImageAddressSpace();
bool IsImageAddressSpaceReady() const {
for (const ImageInfo& image_info : image_infos_) {
if (image_info.image_roots_address_ == 0u) {
return false;
return true;
template <typename T>
T* GetImageAddress(T* object) const SHARED_REQUIRES(Locks::mutator_lock_) {
if (object == nullptr || IsInBootImage(object)) {
return object;
} else {
size_t oat_index = GetOatIndex(object);
const ImageInfo& image_info = GetImageInfo(oat_index);
return reinterpret_cast<T*>(image_info.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 oat_it = dex_file_oat_index_map_.find(dex_file);
DCHECK(oat_it != dex_file_oat_index_map_.end());
const ImageInfo& image_info = GetImageInfo(oat_it->second);
auto it = image_info.dex_cache_array_starts_.find(dex_file);
DCHECK(it != image_info.dex_cache_array_starts_.end());
return reinterpret_cast<PtrType>(
image_info.image_begin_ + image_info.bin_slot_offsets_[kBinDexCacheArray] +
it->second + offset);
size_t GetOatFileOffset(size_t oat_index) const {
return GetImageInfo(oat_index).oat_offset_;
const uint8_t* GetOatFileBegin(size_t oat_index) const {
return GetImageInfo(oat_index).oat_file_begin_;
// If image_fd is not kInvalidFd, then we use that for the image file. Otherwise we open
// the names in image_filenames.
// If oat_fd is not kInvalidFd, then we use that for the oat file. Otherwise we open
// the names in oat_filenames.
bool Write(int image_fd,
const std::vector<const char*>& image_filenames,
const std::vector<const char*>& oat_filenames)
uintptr_t GetOatDataBegin(size_t oat_index) {
return reinterpret_cast<uintptr_t>(GetImageInfo(oat_index).oat_data_begin_);
// Get the index of the oat file containing the dex file.
// This "oat_index" is used to retrieve information about the the memory layout
// of the oat file and its associated image file, needed for link-time patching
// of references to the image or across oat files.
size_t GetOatIndexForDexFile(const DexFile* dex_file) const;
// Get the index of the oat file containing the dex file served by the dex cache.
size_t GetOatIndexForDexCache(mirror::DexCache* dex_cache) const
// Update the oat layout for the given oat file.
// This will make the oat_offset for the next oat file valid.
void UpdateOatFileLayout(size_t oat_index,
size_t oat_loaded_size,
size_t oat_data_offset,
size_t oat_data_size);
// Update information about the oat header, i.e. checksum and trampoline offsets.
void UpdateOatFileHeader(size_t oat_index, const OatHeader& oat_header);
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);
enum OatAddress {
// Number of elements in the enum.
friend std::ostream& operator<<(std::ostream& stream, const OatAddress& oat_address);
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_;
struct ImageInfo {
ImageInfo(ImageInfo&&) = default;
// Create the image sections into the out sections variable, returns the size of the image
// excluding the bitmap.
size_t CreateImageSections(size_t target_ptr_size, ImageSection* out_sections) const;
std::unique_ptr<MemMap> image_; // Memory mapped for generating the image.
// Target begin of this image. Notes: It is not valid to write here, this is the address
// of the target image, not necessarily where image_ is mapped. The address is only valid
// after layouting (otherwise null).
uint8_t* image_begin_ = nullptr;
// Offset to the free space in image_, initially size of image header.
size_t image_end_ = RoundUp(sizeof(ImageHeader), kObjectAlignment);
uint32_t image_roots_address_ = 0; // The image roots address in the image.
size_t image_offset_ = 0; // Offset of this image from the start of the first image.
// Image size is the *address space* covered by this image. As the live bitmap is aligned
// to the page size, the live bitmap will cover more address space than necessary. But live
// bitmaps may not overlap, so an image has a "shadow," which is accounted for in the size.
// The next image may only start at image_begin_ + image_size_ (which is guaranteed to be
// page-aligned).
size_t image_size_ = 0;
// Oat data.
// Offset of the oat file for this image from start of oat files. This is
// valid when the previous oat file has been written.
size_t oat_offset_ = 0;
// Layout of the loaded ELF file containing the oat file, valid after UpdateOatFileLayout().
const uint8_t* oat_file_begin_ = nullptr;
size_t oat_loaded_size_ = 0;
const uint8_t* oat_data_begin_ = nullptr;
size_t oat_size_ = 0; // Size of the corresponding oat data.
// The oat header checksum, valid after UpdateOatFileHeader().
uint32_t oat_checksum_ = 0u;
// Image bitmap which lets us know where the objects inside of the image reside.
std::unique_ptr<gc::accounting::ContinuousSpaceBitmap> image_bitmap_;
// The start offsets of the dex cache arrays.
SafeMap<const DexFile*, size_t> dex_cache_array_starts_;
// Offset from oat_data_begin_ to the stubs.
uint32_t oat_address_offsets_[kOatAddressCount] = {};
// 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_ = 0;
// Number of image class table bytes.
size_t class_table_bytes_ = 0;
// Intern table associated with this image for serialization.
std::unique_ptr<InternTable> intern_table_;
// Class table associated with this image for serialization.
std::unique_ptr<ClassTable> class_table_;
// 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, mirror::DexCache* dex_cache)
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);
size_t oat_index = GetOatIndex(object);
const ImageInfo& image_info = GetImageInfo(oat_index);
uint8_t* dst = image_info.image_->Begin() + offset;
return reinterpret_cast<mirror::Object*>(dst);
// Returns the address in the boot image if we are compiling the app image.
const uint8_t* GetOatAddress(OatAddress type) const;
const uint8_t* GetOatAddressForOffset(uint32_t offset, const ImageInfo& image_info) const {
// With Quick, code is within the OatFile, as there are all in one
// .o ELF object. But interpret it as signed.
DCHECK_LE(static_cast<int32_t>(offset), static_cast<int32_t>(image_info.oat_size_));
DCHECK(image_info.oat_data_begin_ != nullptr);
return offset == 0u ? nullptr : image_info.oat_data_begin_ + static_cast<int32_t>(offset);
// Returns true if the class was in the original requested image classes list.
bool KeepClass(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_index)
mirror::ObjectArray<mirror::Object>* CreateImageRoots(size_t oat_index) 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(size_t oat_index) 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, const ImageInfo& image_info)
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)
// Get quick code for non-resolution/imt_conflict/abstract method.
const uint8_t* GetQuickCode(ArtMethod* method,
const ImageInfo& image_info,
bool* quick_is_interpreted)
// Calculate the sum total of the bin slot sizes in [0, up_to). Defaults to all bins.
size_t GetBinSizeSum(ImageInfo& image_info, 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,
size_t oat_index)
// Return true if klass is loaded by the boot class loader but not in the boot image.
bool IsBootClassLoaderNonImageClass(mirror::Class* klass) SHARED_REQUIRES(Locks::mutator_lock_);
// Return true if klass depends on a boot class loader non image class. We want to prune these
// classes since we do not want any boot class loader classes in the image. This means that
// we also cannot have any classes which refer to these boot class loader non image classes.
// PruneAppImageClass also prunes if klass depends on a non-image class according to the compiler
// driver.
bool PruneAppImageClass(mirror::Class* klass)
// early_exit is true if we had a cyclic dependency anywhere down the chain.
bool PruneAppImageClassInternal(mirror::Class* klass,
bool* early_exit,
std::unordered_set<mirror::Class*>* visited)
static Bin BinTypeForNativeRelocationType(NativeObjectRelocationType type);
uintptr_t NativeOffsetInImage(void* obj);
// Location of where the object will be when the image is loaded at runtime.
template <typename T>
T* NativeLocationInImage(T* obj) SHARED_REQUIRES(Locks::mutator_lock_);
// Location of where the temporary copy of the object currently is.
template <typename T>
T* NativeCopyLocation(T* obj, mirror::DexCache* dex_cache) SHARED_REQUIRES(Locks::mutator_lock_);
// Return true of obj is inside of the boot image space. This may only return true if we are
// compiling an app image.
bool IsInBootImage(const void* obj) const;
// Return true if ptr is within the boot oat file.
bool IsInBootOatFile(const void* ptr) const;
// Get the index of the oat file associated with the object.
size_t GetOatIndex(mirror::Object* object) const SHARED_REQUIRES(Locks::mutator_lock_);
// The oat index for shared data in multi-image and all data in single-image compilation.
size_t GetDefaultOatIndex() const {
return 0u;
ImageInfo& GetImageInfo(size_t oat_index) {
return image_infos_[oat_index];
const ImageInfo& GetImageInfo(size_t oat_index) const {
return image_infos_[oat_index];
// Find an already strong interned string in the other images or in the boot image. Used to
// remove duplicates in the multi image and app image case.
mirror::String* FindInternedString(mirror::String* string) SHARED_REQUIRES(Locks::mutator_lock_);
const CompilerDriver& compiler_driver_;
// Beginning target image address for the first image.
uint8_t* global_image_begin_;
// Offset from image_begin_ to where the first object is in image_.
size_t image_objects_offset_begin_;
// 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_;
// 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_;
// Boolean flags.
const bool compile_pic_;
const bool compile_app_image_;
// Size of pointers on the target architecture.
size_t target_ptr_size_;
// Image data indexed by the oat file index.
dchecked_vector<ImageInfo> image_infos_;
// 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 {
size_t oat_index;
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_;
// Prune class memoization table to speed up ContainsBootClassLoaderNonImageClass.
std::unordered_map<mirror::Class*, bool> prune_class_memo_;
// Class loaders with a class table to write out. There should only be one class loader because
// dex2oat loads the dex files to be compiled into a single class loader. For the boot image,
// null is a valid entry.
std::unordered_set<mirror::ClassLoader*> class_loaders_;
// Which mode the image is stored as, see image.h
const ImageHeader::StorageMode image_storage_mode_;
// The file names of oat files.
const std::vector<const char*>& oat_filenames_;
// Map of dex files to the indexes of oat files that they were compiled into.
const std::unordered_map<const DexFile*, size_t>& dex_file_oat_index_map_;
friend class ContainsBootClassLoaderNonImageClassVisitor;
friend class FixupClassVisitor;
friend class FixupRootVisitor;
friend class FixupVisitor;
friend class NativeLocationVisitor;
friend class NonImageClassesVisitor;
} // namespace art