blob: c367957bc3a435240ae4e22658f890fc176f73ea [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 "base/bit_utils.h"
#include "gc/allocator_type.h"
#include "class.h"
#include "object.h"
#include "runtime_globals.h"
namespace art {
template<class T> class Handle;
struct StringOffsets;
class StringPiece;
class StubTest_ReadBarrierForRoot_Test;
namespace mirror {
// String Compression
static constexpr bool kUseStringCompression = true;
enum class StringCompressionFlag : uint32_t {
kCompressed = 0u,
kUncompressed = 1u
// C++ mirror of java.lang.String
class MANAGED String final : public Object {
// Size of java.lang.String.class.
static uint32_t ClassSize(PointerSize pointer_size);
// Size of an instance of java.lang.String not including its value array.
static constexpr uint32_t InstanceSize() {
return sizeof(String);
static constexpr MemberOffset CountOffset() {
return OFFSET_OF_OBJECT_MEMBER(String, count_);
static constexpr MemberOffset ValueOffset() {
return OFFSET_OF_OBJECT_MEMBER(String, value_);
uint16_t* GetValue() REQUIRES_SHARED(Locks::mutator_lock_) {
return &value_[0];
uint8_t* GetValueCompressed() REQUIRES_SHARED(Locks::mutator_lock_) {
return &value_compressed_[0];
template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
size_t SizeOf() REQUIRES_SHARED(Locks::mutator_lock_) {
size_t size = sizeof(String);
if (IsCompressed()) {
size += (sizeof(uint8_t) * GetLength<kVerifyFlags>());
} else {
size += (sizeof(uint16_t) * GetLength<kVerifyFlags>());
// String.equals() intrinsics assume zero-padding up to kObjectAlignment,
// so make sure the zero-padding is actually copied around if GC compaction
// chooses to copy only SizeOf() bytes.
// http://b/23528461
return RoundUp(size, kObjectAlignment);
// Taking out the first/uppermost bit because it is not part of actual length value
template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
int32_t GetLength() REQUIRES_SHARED(Locks::mutator_lock_) {
return GetLengthFromCount(GetCount<kVerifyFlags>());
template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
int32_t GetCount() REQUIRES_SHARED(Locks::mutator_lock_) {
return GetField32<kVerifyFlags>(OFFSET_OF_OBJECT_MEMBER(String, count_));
void SetCount(int32_t new_count) REQUIRES_SHARED(Locks::mutator_lock_) {
// Count is invariant so use non-transactional mode. Also disable check as we may run inside
// a transaction.
SetField32<false, false>(OFFSET_OF_OBJECT_MEMBER(String, count_), new_count);
int32_t GetHashCode() REQUIRES_SHARED(Locks::mutator_lock_);
// Computes, stores, and returns the hash code.
int32_t ComputeHashCode() REQUIRES_SHARED(Locks::mutator_lock_);
int32_t GetUtfLength() REQUIRES_SHARED(Locks::mutator_lock_);
uint16_t CharAt(int32_t index) REQUIRES_SHARED(Locks::mutator_lock_);
// Create a new string where all occurences of `old_c` are replaced with `new_c`.
// String.doReplace(char, char) is called from String.replace(char, char) when there is a match.
static ObjPtr<String> DoReplace(Thread* self, Handle<String> src, uint16_t old_c, uint16_t new_c)
ObjPtr<String> Intern() REQUIRES_SHARED(Locks::mutator_lock_);
template <bool kIsInstrumented>
ALWAYS_INLINE static String* AllocFromByteArray(Thread* self, int32_t byte_length,
Handle<ByteArray> array, int32_t offset,
int32_t high_byte,
gc::AllocatorType allocator_type)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!Roles::uninterruptible_);
template <bool kIsInstrumented>
ALWAYS_INLINE static String* AllocFromCharArray(Thread* self, int32_t count,
Handle<CharArray> array, int32_t offset,
gc::AllocatorType allocator_type)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!Roles::uninterruptible_);
template <bool kIsInstrumented>
ALWAYS_INLINE static String* AllocFromString(Thread* self, int32_t string_length,
Handle<String> string, int32_t offset,
gc::AllocatorType allocator_type)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!Roles::uninterruptible_);
template <bool kIsInstrumented>
ALWAYS_INLINE static String* AllocEmptyString(Thread* self,
gc::AllocatorType allocator_type)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!Roles::uninterruptible_);
static String* AllocFromStrings(Thread* self, Handle<String> string, Handle<String> string2)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!Roles::uninterruptible_);
static String* AllocFromUtf16(Thread* self, int32_t utf16_length, const uint16_t* utf16_data_in)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!Roles::uninterruptible_);
static String* AllocFromModifiedUtf8(Thread* self, const char* utf)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!Roles::uninterruptible_);
static String* AllocFromModifiedUtf8(Thread* self, int32_t utf16_length,
const char* utf8_data_in, int32_t utf8_length)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!Roles::uninterruptible_);
static String* AllocFromModifiedUtf8(Thread* self, int32_t utf16_length, const char* utf8_data_in)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!Roles::uninterruptible_);
// TODO: This is only used in the interpreter to compare against
// entries from a dex files constant pool (ArtField names). Should
// we unify this with Equals(const StringPiece&); ?
bool Equals(const char* modified_utf8) REQUIRES_SHARED(Locks::mutator_lock_);
// TODO: This is only used to compare DexCache.location with
// a dex_file's location (which is an std::string). Do we really
// need this in mirror::String just for that one usage ?
bool Equals(const StringPiece& modified_utf8)
bool Equals(ObjPtr<String> that) REQUIRES_SHARED(Locks::mutator_lock_);
// Compare UTF-16 code point values not in a locale-sensitive manner
int Compare(int32_t utf16_length, const char* utf8_data_in);
// TODO: do we need this overload? give it a more intention-revealing name.
bool Equals(const uint16_t* that_chars, int32_t that_offset,
int32_t that_length)
// Create a modified UTF-8 encoded std::string from a java/lang/String object.
std::string ToModifiedUtf8() REQUIRES_SHARED(Locks::mutator_lock_);
int32_t FastIndexOf(int32_t ch, int32_t start) REQUIRES_SHARED(Locks::mutator_lock_);
template <typename MemoryType>
int32_t FastIndexOf(MemoryType* chars, int32_t ch, int32_t start)
int32_t CompareTo(ObjPtr<String> other) REQUIRES_SHARED(Locks::mutator_lock_);
CharArray* ToCharArray(Thread* self) REQUIRES_SHARED(Locks::mutator_lock_)
void GetChars(int32_t start, int32_t end, Handle<CharArray> array, int32_t index)
template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
bool IsCompressed() REQUIRES_SHARED(Locks::mutator_lock_) {
return kUseStringCompression && IsCompressed(GetCount());
bool IsValueNull() REQUIRES_SHARED(Locks::mutator_lock_);
template<typename MemoryType>
static bool AllASCII(const MemoryType* chars, const int length);
static bool DexFileStringAllASCII(const char* chars, const int length);
ALWAYS_INLINE static bool IsCompressed(int32_t count) {
return GetCompressionFlagFromCount(count) == StringCompressionFlag::kCompressed;
ALWAYS_INLINE static StringCompressionFlag GetCompressionFlagFromCount(int32_t count) {
return kUseStringCompression
? static_cast<StringCompressionFlag>(static_cast<uint32_t>(count) & 1u)
: StringCompressionFlag::kUncompressed;
ALWAYS_INLINE static int32_t GetLengthFromCount(int32_t count) {
return kUseStringCompression ? static_cast<int32_t>(static_cast<uint32_t>(count) >> 1) : count;
ALWAYS_INLINE static int32_t GetFlaggedCount(int32_t length, bool compressible) {
return kUseStringCompression
? static_cast<int32_t>((static_cast<uint32_t>(length) << 1) |
? StringCompressionFlag::kCompressed
: StringCompressionFlag::kUncompressed)))
: length;
// Returns a human-readable equivalent of 'descriptor'. So "I" would be "int",
// "[[I" would be "int[][]", "[Ljava/lang/String;" would be
// "java.lang.String[]", and so forth.
static std::string PrettyStringDescriptor(ObjPtr<mirror::String> descriptor)
std::string PrettyStringDescriptor()
static constexpr bool IsASCII(uint16_t c) {
// Valid ASCII characters are in range 1..0x7f. Zero is not considered ASCII
// because it would complicate the detection of ASCII strings in Modified-UTF8.
return (c - 1u) < 0x7fu;
static bool AllASCIIExcept(const uint16_t* chars, int32_t length, uint16_t non_ascii);
void SetHashCode(int32_t new_hash_code) REQUIRES_SHARED(Locks::mutator_lock_) {
// Hash code is invariant so use non-transactional mode. Also disable check as we may run inside
// a transaction.
DCHECK_EQ(0, GetField32(OFFSET_OF_OBJECT_MEMBER(String, hash_code_)));
SetField32<false, false>(OFFSET_OF_OBJECT_MEMBER(String, hash_code_), new_hash_code);
template <bool kIsInstrumented, typename PreFenceVisitor>
ALWAYS_INLINE static String* Alloc(Thread* self, int32_t utf16_length_with_flag,
gc::AllocatorType allocator_type,
const PreFenceVisitor& pre_fence_visitor)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!Roles::uninterruptible_);
// Field order required by test "ValidateFieldOrderOfJavaCppUnionClasses".
// If string compression is enabled, count_ holds the StringCompressionFlag in the
// least significant bit and the length in the remaining bits, length = count_ >> 1.
int32_t count_;
uint32_t hash_code_;
// Compression of all-ASCII into 8-bit memory leads to usage one of these fields
union {
uint16_t value_[0];
uint8_t value_compressed_[0];
friend struct art::StringOffsets; // for verifying offset information
} // namespace mirror
} // namespace art