runtime/mirror/string-alloc-inl.h - LeafOS-Project/android_art - Gitiles

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

 #include "string-inl.h"

 #include "android-base/endian.h"
 #include "android-base/stringprintf.h"

 #include "array.h"
 #include "base/bit_utils.h"
 #include "class.h"
 #include "class_root-inl.h"
 #include "gc/allocator_type.h"
 #include "gc/heap-inl.h"
 #include "obj_ptr.h"
 #include "runtime.h"
 #include "runtime_globals.h"
 #include "thread.h"

 namespace art {
 namespace mirror {

 // Sets string count in the allocation code path to ensure it is guarded by a CAS.
 class SetStringCountVisitor {
  public:
   explicit SetStringCountVisitor(int32_t count) : count_(count) {
   }

   void operator()(ObjPtr<Object> obj, size_t usable_size ATTRIBUTE_UNUSED) const
       REQUIRES_SHARED(Locks::mutator_lock_) {
     // Avoid AsString as object is not yet in live bitmap or allocation stack.
     ObjPtr<String> string = ObjPtr<String>::DownCast(obj);
     string->SetCount(count_);
     DCHECK_IMPLIES(string->IsCompressed(), kUseStringCompression);
   }

  private:
   const int32_t count_;
 };

 // Sets string count and value in the allocation code path to ensure it is guarded by a CAS.
 class SetStringCountAndBytesVisitor {
  public:
   SetStringCountAndBytesVisitor(int32_t count, Handle<ByteArray> src_array, int32_t offset,
                                 int32_t high_byte)
       : count_(count), src_array_(src_array), offset_(offset), high_byte_(high_byte) {
   }

   void operator()(ObjPtr<Object> obj, size_t usable_size ATTRIBUTE_UNUSED) const
       REQUIRES_SHARED(Locks::mutator_lock_) {
     // Avoid AsString as object is not yet in live bitmap or allocation stack.
     ObjPtr<String> string = ObjPtr<String>::DownCast(obj);
     string->SetCount(count_);
     DCHECK_IMPLIES(string->IsCompressed(), kUseStringCompression);
     int32_t length = String::GetLengthFromCount(count_);
     const uint8_t* const src = reinterpret_cast<uint8_t*>(src_array_->GetData()) + offset_;
     if (string->IsCompressed()) {
       uint8_t* valueCompressed = string->GetValueCompressed();
       for (int i = 0; i < length; i++) {
         valueCompressed[i] = (src[i] & 0xFF);
       }
     } else {
       uint16_t* value = string->GetValue();
       for (int i = 0; i < length; i++) {
         value[i] = high_byte_ + (src[i] & 0xFF);
       }
     }
   }

  private:
   const int32_t count_;
   Handle<ByteArray> src_array_;
   const int32_t offset_;
   const int32_t high_byte_;
 };

 // Sets string count and value in the allocation code path to ensure it is guarded by a CAS.
 class SetStringCountAndUtf16BytesVisitor {
  public:
   SetStringCountAndUtf16BytesVisitor(int32_t count, Handle<ByteArray> src_array, int32_t offset)
       : count_(count), src_array_(src_array), offset_(offset) {
   }

   void operator()(ObjPtr<Object> obj, size_t usable_size ATTRIBUTE_UNUSED) const
       REQUIRES_SHARED(Locks::mutator_lock_) {
     // Avoid AsString as object is not yet in live bitmap or allocation stack.
     ObjPtr<String> string = ObjPtr<String>::DownCast(obj);
     string->SetCount(count_);
     DCHECK_IMPLIES(string->IsCompressed(), kUseStringCompression);
     uint32_t length = String::GetLengthFromCount(count_);
     const uint8_t* const src = reinterpret_cast<uint8_t*>(src_array_->GetData()) + offset_;
     if (UNLIKELY(string->IsCompressed())) {
       uint8_t* valueCompressed = string->GetValueCompressed();
       for (uint32_t i = 0; i < length; i++) {
         valueCompressed[i] = (src[i << 1] & 0xFF);
       }
     } else {
       uint16_t* value = string->GetValue();
       for (uint32_t i = 0; i < length; i++) {
         uint32_t index = (i << 1);
         value[i] = (src[index] & 0xFF) + ((src[index + 1] & 0xFF) << 8);
       }
     }
   }

  private:
   const int32_t count_;
   Handle<ByteArray> src_array_;
   const int32_t offset_;
 };

 // Sets string count and value in the allocation code path to ensure it is guarded by a CAS.
 class SetStringCountAndValueVisitorFromCharArray {
  public:
   SetStringCountAndValueVisitorFromCharArray(int32_t count, Handle<CharArray> src_array,
                                              int32_t offset) :
     count_(count), src_array_(src_array), offset_(offset) {
   }

   void operator()(ObjPtr<Object> obj, size_t usable_size ATTRIBUTE_UNUSED) const
       REQUIRES_SHARED(Locks::mutator_lock_) {
     // Avoid AsString as object is not yet in live bitmap or allocation stack.
     ObjPtr<String> string = ObjPtr<String>::DownCast(obj);
     string->SetCount(count_);
     const uint16_t* const src = src_array_->GetData() + offset_;
     const int32_t length = String::GetLengthFromCount(count_);
     if (kUseStringCompression && String::IsCompressed(count_)) {
       for (int i = 0; i < length; ++i) {
         string->GetValueCompressed()[i] = static_cast<uint8_t>(src[i]);
       }
     } else {
       memcpy(string->GetValue(), src, length * sizeof(uint16_t));
     }
   }

  private:
   const int32_t count_;
   Handle<CharArray> src_array_;
   const int32_t offset_;
 };

 // Sets string count and value in the allocation code path to ensure it is guarded by a CAS.
 class SetStringCountAndValueVisitorFromString {
  public:
   SetStringCountAndValueVisitorFromString(int32_t count,
                                           Handle<String> src_string,
                                           int32_t offset) :
     count_(count), src_string_(src_string), offset_(offset) {
   }

   void operator()(ObjPtr<Object> obj, size_t usable_size ATTRIBUTE_UNUSED) const
       REQUIRES_SHARED(Locks::mutator_lock_) {
     // Avoid AsString as object is not yet in live bitmap or allocation stack.
     ObjPtr<String> string = ObjPtr<String>::DownCast(obj);
     string->SetCount(count_);
     const int32_t length = String::GetLengthFromCount(count_);
     bool compressible = kUseStringCompression && String::IsCompressed(count_);
     if (src_string_->IsCompressed()) {
       const uint8_t* const src = src_string_->GetValueCompressed() + offset_;
       memcpy(string->GetValueCompressed(), src, length * sizeof(uint8_t));
     } else {
       const uint16_t* const src = src_string_->GetValue() + offset_;
       if (compressible) {
         for (int i = 0; i < length; ++i) {
           string->GetValueCompressed()[i] = static_cast<uint8_t>(src[i]);
         }
       } else {
         memcpy(string->GetValue(), src, length * sizeof(uint16_t));
       }
     }
   }

  private:
   const int32_t count_;
   Handle<String> src_string_;
   const int32_t offset_;
 };

 template <bool kIsInstrumented, typename PreFenceVisitor>
 inline ObjPtr<String> String::Alloc(Thread* self,
                                     int32_t utf16_length_with_flag,
                                     gc::AllocatorType allocator_type,
                                     const PreFenceVisitor& pre_fence_visitor) {
   constexpr size_t header_size = sizeof(String);
   const bool compressible = kUseStringCompression && String::IsCompressed(utf16_length_with_flag);
   const size_t block_size = (compressible) ? sizeof(uint8_t) : sizeof(uint16_t);
   size_t length = String::GetLengthFromCount(utf16_length_with_flag);
   static_assert(sizeof(length) <= sizeof(size_t),
                 "static_cast<size_t>(utf16_length) must not lose bits.");
   size_t data_size = block_size * length;
   size_t size = header_size + data_size;
   // String.equals() intrinsics assume zero-padding up to kObjectAlignment,
   // so make sure the allocator clears the padding as well.
   // http://b/23528461
   size_t alloc_size = RoundUp(size, kObjectAlignment);

   Runtime* runtime = Runtime::Current();
   ObjPtr<Class> string_class = GetClassRoot<String>(runtime->GetClassLinker());
   // Check for overflow and throw OutOfMemoryError if this was an unreasonable request.
   // Do this by comparing with the maximum length that will _not_ cause an overflow.
   const size_t overflow_length = (-header_size) / block_size;   // Unsigned arithmetic.
   const size_t max_alloc_length = overflow_length - 1u;
   static_assert(IsAligned<sizeof(uint16_t)>(kObjectAlignment),
                 "kObjectAlignment must be at least as big as Java char alignment");
   const size_t max_length = RoundDown(max_alloc_length, kObjectAlignment / block_size);
   if (UNLIKELY(length > max_length)) {
     self->ThrowOutOfMemoryError(
         android::base::StringPrintf("%s of length %d would overflow",
                                     Class::PrettyDescriptor(string_class).c_str(),
                                     static_cast<int>(length)).c_str());
     return nullptr;
   }

   gc::Heap* heap = runtime->GetHeap();
   return ObjPtr<String>::DownCast(
       heap->AllocObjectWithAllocator<kIsInstrumented>(self,
                                                       string_class,
                                                       alloc_size,
                                                       allocator_type,
                                                       pre_fence_visitor));
 }

 template <bool kIsInstrumented>
 inline ObjPtr<String> String::AllocEmptyString(Thread* self, gc::AllocatorType allocator_type) {
   const int32_t length_with_flag = String::GetFlaggedCount(0, /* compressible= */ true);
   SetStringCountVisitor visitor(length_with_flag);
   return Alloc<kIsInstrumented>(self, length_with_flag, allocator_type, visitor);
 }

 template <bool kIsInstrumented>
 inline ObjPtr<String> String::AllocFromByteArray(Thread* self,
                                                  int32_t byte_length,
                                                  Handle<ByteArray> array,
                                                  int32_t offset,
                                                  int32_t high_byte,
                                                  gc::AllocatorType allocator_type) {
   const uint8_t* const src = reinterpret_cast<uint8_t*>(array->GetData()) + offset;
   high_byte &= 0xff;  // Extract the relevant bits before determining `compressible`.
   const bool compressible =
       kUseStringCompression &&
       String::AllASCII<uint8_t>(src, byte_length) &&
       (high_byte == 0 || byte_length == 0);
   const int32_t length_with_flag = String::GetFlaggedCount(byte_length, compressible);
   SetStringCountAndBytesVisitor visitor(length_with_flag, array, offset, high_byte << 8);
   return Alloc<kIsInstrumented>(self, length_with_flag, allocator_type, visitor);
 }

 template <bool kIsInstrumented>
 inline ObjPtr<String> String::AllocFromUtf16ByteArray(Thread* self,
                                                       int32_t char_count,
                                                       Handle<ByteArray> array,
                                                       int32_t offset,
                                                       gc::AllocatorType allocator_type) {
   static_assert(__BYTE_ORDER == __LITTLE_ENDIAN,
       "Please update this function and java-side callers to support big endian.");
   const uint8_t* const src = reinterpret_cast<uint8_t*>(array->GetData()) + offset;
   bool compressible = kUseStringCompression;
   if (compressible) {
     uint32_t byte_count = (static_cast<uint32_t>(char_count) << 1);
     for (uint32_t i = 0; i < byte_count; i += 2) {
       if (!IsASCII((src[i] & 0xff) + ((src[i + 1] & 0xff) << 8))) {
         compressible = false;
         break;
       }
     }
   }
   const int32_t length_with_flag = String::GetFlaggedCount(char_count, compressible);
   SetStringCountAndUtf16BytesVisitor visitor(length_with_flag, array, offset);
   return Alloc<kIsInstrumented>(self, length_with_flag, allocator_type, visitor);
 }

 template <bool kIsInstrumented>
 inline ObjPtr<String> String::AllocFromCharArray(Thread* self,
                                                  int32_t count,
                                                  Handle<CharArray> array,
                                                  int32_t offset,
                                                  gc::AllocatorType allocator_type) {
   // It is a caller error to have a count less than the actual array's size.
   DCHECK_GE(array->GetLength(), count);
   const bool compressible = kUseStringCompression &&
                             String::AllASCII<uint16_t>(array->GetData() + offset, count);
   const int32_t length_with_flag = String::GetFlaggedCount(count, compressible);
   SetStringCountAndValueVisitorFromCharArray visitor(length_with_flag, array, offset);
   return Alloc<kIsInstrumented>(self, length_with_flag, allocator_type, visitor);
 }

 template <bool kIsInstrumented>
 inline ObjPtr<String> String::AllocFromString(Thread* self,
                                               int32_t string_length,
                                               Handle<String> string,
                                               int32_t offset,
                                               gc::AllocatorType allocator_type) {
   const bool compressible = kUseStringCompression &&
       ((string->IsCompressed()) ? true : String::AllASCII<uint16_t>(string->GetValue() + offset,
                                                                     string_length));
   const int32_t length_with_flag = String::GetFlaggedCount(string_length, compressible);
   SetStringCountAndValueVisitorFromString visitor(length_with_flag, string, offset);
   return Alloc<kIsInstrumented>(self, length_with_flag, allocator_type, visitor);
 }

 }  // namespace mirror
 }  // namespace art

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

	#include "string-inl.h"

	#include "android-base/endian.h"
	#include "android-base/stringprintf.h"

	#include "array.h"
	#include "base/bit_utils.h"
	#include "class.h"
	#include "class_root-inl.h"
	#include "gc/allocator_type.h"
	#include "gc/heap-inl.h"
	#include "obj_ptr.h"
	#include "runtime.h"
	#include "runtime_globals.h"
	#include "thread.h"

	namespace art {
	namespace mirror {

	// Sets string count in the allocation code path to ensure it is guarded by a CAS.
	class SetStringCountVisitor {
	public:
	explicit SetStringCountVisitor(int32_t count) : count_(count) {
	}

	void operator()(ObjPtr<Object> obj, size_t usable_size ATTRIBUTE_UNUSED) const
	REQUIRES_SHARED(Locks::mutator_lock_) {
	// Avoid AsString as object is not yet in live bitmap or allocation stack.
	ObjPtr<String> string = ObjPtr<String>::DownCast(obj);
	string->SetCount(count_);
	DCHECK_IMPLIES(string->IsCompressed(), kUseStringCompression);
	}

	private:
	const int32_t count_;
	};

	// Sets string count and value in the allocation code path to ensure it is guarded by a CAS.
	class SetStringCountAndBytesVisitor {
	public:
	SetStringCountAndBytesVisitor(int32_t count, Handle<ByteArray> src_array, int32_t offset,
	int32_t high_byte)
	: count_(count), src_array_(src_array), offset_(offset), high_byte_(high_byte) {
	}

	void operator()(ObjPtr<Object> obj, size_t usable_size ATTRIBUTE_UNUSED) const
	REQUIRES_SHARED(Locks::mutator_lock_) {
	// Avoid AsString as object is not yet in live bitmap or allocation stack.
	ObjPtr<String> string = ObjPtr<String>::DownCast(obj);
	string->SetCount(count_);
	DCHECK_IMPLIES(string->IsCompressed(), kUseStringCompression);
	int32_t length = String::GetLengthFromCount(count_);
	const uint8_t* const src = reinterpret_cast<uint8_t*>(src_array_->GetData()) + offset_;
	if (string->IsCompressed()) {
	uint8_t* valueCompressed = string->GetValueCompressed();
	for (int i = 0; i < length; i++) {
	valueCompressed[i] = (src[i] & 0xFF);
	}
	} else {
	uint16_t* value = string->GetValue();
	for (int i = 0; i < length; i++) {
	value[i] = high_byte_ + (src[i] & 0xFF);
	}
	}
	}

	private:
	const int32_t count_;
	Handle<ByteArray> src_array_;
	const int32_t offset_;
	const int32_t high_byte_;
	};

	// Sets string count and value in the allocation code path to ensure it is guarded by a CAS.
	class SetStringCountAndUtf16BytesVisitor {
	public:
	SetStringCountAndUtf16BytesVisitor(int32_t count, Handle<ByteArray> src_array, int32_t offset)
	: count_(count), src_array_(src_array), offset_(offset) {
	}

	void operator()(ObjPtr<Object> obj, size_t usable_size ATTRIBUTE_UNUSED) const
	REQUIRES_SHARED(Locks::mutator_lock_) {
	// Avoid AsString as object is not yet in live bitmap or allocation stack.
	ObjPtr<String> string = ObjPtr<String>::DownCast(obj);
	string->SetCount(count_);
	DCHECK_IMPLIES(string->IsCompressed(), kUseStringCompression);
	uint32_t length = String::GetLengthFromCount(count_);
	const uint8_t* const src = reinterpret_cast<uint8_t*>(src_array_->GetData()) + offset_;
	if (UNLIKELY(string->IsCompressed())) {
	uint8_t* valueCompressed = string->GetValueCompressed();
	for (uint32_t i = 0; i < length; i++) {
	valueCompressed[i] = (src[i << 1] & 0xFF);
	}
	} else {
	uint16_t* value = string->GetValue();
	for (uint32_t i = 0; i < length; i++) {
	uint32_t index = (i << 1);
	value[i] = (src[index] & 0xFF) + ((src[index + 1] & 0xFF) << 8);
	}
	}
	}

	private:
	const int32_t count_;
	Handle<ByteArray> src_array_;
	const int32_t offset_;
	};

	// Sets string count and value in the allocation code path to ensure it is guarded by a CAS.
	class SetStringCountAndValueVisitorFromCharArray {
	public:
	SetStringCountAndValueVisitorFromCharArray(int32_t count, Handle<CharArray> src_array,
	int32_t offset) :
	count_(count), src_array_(src_array), offset_(offset) {
	}

	void operator()(ObjPtr<Object> obj, size_t usable_size ATTRIBUTE_UNUSED) const
	REQUIRES_SHARED(Locks::mutator_lock_) {
	// Avoid AsString as object is not yet in live bitmap or allocation stack.
	ObjPtr<String> string = ObjPtr<String>::DownCast(obj);
	string->SetCount(count_);
	const uint16_t* const src = src_array_->GetData() + offset_;
	const int32_t length = String::GetLengthFromCount(count_);
	if (kUseStringCompression && String::IsCompressed(count_)) {
	for (int i = 0; i < length; ++i) {
	string->GetValueCompressed()[i] = static_cast<uint8_t>(src[i]);
	}
	} else {
	memcpy(string->GetValue(), src, length * sizeof(uint16_t));
	}
	}

	private:
	const int32_t count_;
	Handle<CharArray> src_array_;
	const int32_t offset_;
	};

	// Sets string count and value in the allocation code path to ensure it is guarded by a CAS.
	class SetStringCountAndValueVisitorFromString {
	public:
	SetStringCountAndValueVisitorFromString(int32_t count,
	Handle<String> src_string,
	int32_t offset) :
	count_(count), src_string_(src_string), offset_(offset) {
	}

	void operator()(ObjPtr<Object> obj, size_t usable_size ATTRIBUTE_UNUSED) const
	REQUIRES_SHARED(Locks::mutator_lock_) {
	// Avoid AsString as object is not yet in live bitmap or allocation stack.
	ObjPtr<String> string = ObjPtr<String>::DownCast(obj);
	string->SetCount(count_);
	const int32_t length = String::GetLengthFromCount(count_);
	bool compressible = kUseStringCompression && String::IsCompressed(count_);
	if (src_string_->IsCompressed()) {
	const uint8_t* const src = src_string_->GetValueCompressed() + offset_;
	memcpy(string->GetValueCompressed(), src, length * sizeof(uint8_t));
	} else {
	const uint16_t* const src = src_string_->GetValue() + offset_;
	if (compressible) {
	for (int i = 0; i < length; ++i) {
	string->GetValueCompressed()[i] = static_cast<uint8_t>(src[i]);
	}
	} else {
	memcpy(string->GetValue(), src, length * sizeof(uint16_t));
	}
	}
	}

	private:
	const int32_t count_;
	Handle<String> src_string_;
	const int32_t offset_;
	};

	template <bool kIsInstrumented, typename PreFenceVisitor>
	inline ObjPtr<String> String::Alloc(Thread* self,
	int32_t utf16_length_with_flag,
	gc::AllocatorType allocator_type,
	const PreFenceVisitor& pre_fence_visitor) {
	constexpr size_t header_size = sizeof(String);
	const bool compressible = kUseStringCompression && String::IsCompressed(utf16_length_with_flag);
	const size_t block_size = (compressible) ? sizeof(uint8_t) : sizeof(uint16_t);
	size_t length = String::GetLengthFromCount(utf16_length_with_flag);
	static_assert(sizeof(length) <= sizeof(size_t),
	"static_cast<size_t>(utf16_length) must not lose bits.");
	size_t data_size = block_size * length;
	size_t size = header_size + data_size;
	// String.equals() intrinsics assume zero-padding up to kObjectAlignment,
	// so make sure the allocator clears the padding as well.
	// http://b/23528461
	size_t alloc_size = RoundUp(size, kObjectAlignment);

	Runtime* runtime = Runtime::Current();
	ObjPtr<Class> string_class = GetClassRoot<String>(runtime->GetClassLinker());
	// Check for overflow and throw OutOfMemoryError if this was an unreasonable request.
	// Do this by comparing with the maximum length that will _not_ cause an overflow.
	const size_t overflow_length = (-header_size) / block_size; // Unsigned arithmetic.
	const size_t max_alloc_length = overflow_length - 1u;
	static_assert(IsAligned<sizeof(uint16_t)>(kObjectAlignment),
	"kObjectAlignment must be at least as big as Java char alignment");
	const size_t max_length = RoundDown(max_alloc_length, kObjectAlignment / block_size);
	if (UNLIKELY(length > max_length)) {
	self->ThrowOutOfMemoryError(
	android::base::StringPrintf("%s of length %d would overflow",
	Class::PrettyDescriptor(string_class).c_str(),
	static_cast<int>(length)).c_str());
	return nullptr;
	}

	gc::Heap* heap = runtime->GetHeap();
	return ObjPtr<String>::DownCast(
	heap->AllocObjectWithAllocator<kIsInstrumented>(self,
	string_class,
	alloc_size,
	allocator_type,
	pre_fence_visitor));
	}

	template <bool kIsInstrumented>
	inline ObjPtr<String> String::AllocEmptyString(Thread* self, gc::AllocatorType allocator_type) {
	const int32_t length_with_flag = String::GetFlaggedCount(0, /* compressible= */ true);
	SetStringCountVisitor visitor(length_with_flag);
	return Alloc<kIsInstrumented>(self, length_with_flag, allocator_type, visitor);
	}

	template <bool kIsInstrumented>
	inline ObjPtr<String> String::AllocFromByteArray(Thread* self,
	int32_t byte_length,
	Handle<ByteArray> array,
	int32_t offset,
	int32_t high_byte,
	gc::AllocatorType allocator_type) {
	const uint8_t* const src = reinterpret_cast<uint8_t*>(array->GetData()) + offset;
	high_byte &= 0xff; // Extract the relevant bits before determining `compressible`.
	const bool compressible =
	kUseStringCompression &&
	String::AllASCII<uint8_t>(src, byte_length) &&
	(high_byte == 0 \|\| byte_length == 0);
	const int32_t length_with_flag = String::GetFlaggedCount(byte_length, compressible);
	SetStringCountAndBytesVisitor visitor(length_with_flag, array, offset, high_byte << 8);
	return Alloc<kIsInstrumented>(self, length_with_flag, allocator_type, visitor);
	}

	template <bool kIsInstrumented>
	inline ObjPtr<String> String::AllocFromUtf16ByteArray(Thread* self,
	int32_t char_count,
	Handle<ByteArray> array,
	int32_t offset,
	gc::AllocatorType allocator_type) {
	static_assert(__BYTE_ORDER == __LITTLE_ENDIAN,
	"Please update this function and java-side callers to support big endian.");
	const uint8_t* const src = reinterpret_cast<uint8_t*>(array->GetData()) + offset;
	bool compressible = kUseStringCompression;
	if (compressible) {
	uint32_t byte_count = (static_cast<uint32_t>(char_count) << 1);
	for (uint32_t i = 0; i < byte_count; i += 2) {
	if (!IsASCII((src[i] & 0xff) + ((src[i + 1] & 0xff) << 8))) {
	compressible = false;
	break;
	}
	}
	}
	const int32_t length_with_flag = String::GetFlaggedCount(char_count, compressible);
	SetStringCountAndUtf16BytesVisitor visitor(length_with_flag, array, offset);
	return Alloc<kIsInstrumented>(self, length_with_flag, allocator_type, visitor);
	}

	template <bool kIsInstrumented>
	inline ObjPtr<String> String::AllocFromCharArray(Thread* self,
	int32_t count,
	Handle<CharArray> array,
	int32_t offset,
	gc::AllocatorType allocator_type) {
	// It is a caller error to have a count less than the actual array's size.
	DCHECK_GE(array->GetLength(), count);
	const bool compressible = kUseStringCompression &&
	String::AllASCII<uint16_t>(array->GetData() + offset, count);
	const int32_t length_with_flag = String::GetFlaggedCount(count, compressible);
	SetStringCountAndValueVisitorFromCharArray visitor(length_with_flag, array, offset);
	return Alloc<kIsInstrumented>(self, length_with_flag, allocator_type, visitor);
	}

	template <bool kIsInstrumented>
	inline ObjPtr<String> String::AllocFromString(Thread* self,
	int32_t string_length,
	Handle<String> string,
	int32_t offset,
	gc::AllocatorType allocator_type) {
	const bool compressible = kUseStringCompression &&
	((string->IsCompressed()) ? true : String::AllASCII<uint16_t>(string->GetValue() + offset,
	string_length));
	const int32_t length_with_flag = String::GetFlaggedCount(string_length, compressible);
	SetStringCountAndValueVisitorFromString visitor(length_with_flag, string, offset);
	return Alloc<kIsInstrumented>(self, length_with_flag, allocator_type, visitor);
	}

	} // namespace mirror
	} // namespace art

	#endif // ART_RUNTIME_MIRROR_STRING_ALLOC_INL_H_