mozilla-central/js/src/irregexp/RegExpShim.h (file symbol)

Source code

Revision control

Copy as Markdown

Other Tools

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
// Copyright 2019 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef RegexpShim_h
#define RegexpShim_h
#include "mozilla/Assertions.h"
#include "mozilla/Attributes.h"
#include "mozilla/MathAlgorithms.h"
#include "mozilla/Maybe.h"
#include "mozilla/SegmentedVector.h"
#include "mozilla/Sprintf.h"
#include "mozilla/Types.h"
#include <algorithm>
#include <cctype>
#include <iterator>
#include "irregexp/RegExpTypes.h"
#include "irregexp/util/FlagsShim.h"
#include "irregexp/util/VectorShim.h"
#include "irregexp/util/ZoneShim.h"
#include "jit/JitCode.h"
#include "jit/Label.h"
#include "jit/shared/Assembler-shared.h"
#include "js/friend/StackLimits.h" // js::AutoCheckRecursionLimit
#include "js/RegExpFlags.h"
#include "js/Value.h"
#include "threading/ExclusiveData.h"
#include "util/DifferentialTesting.h"
#include "vm/JSContext.h"
#include "vm/MutexIDs.h"
#include "vm/NativeObject.h"
#include "vm/RegExpShared.h"
// Forward declaration of classes
namespace v8 {
namespace internal {
class Heap;
class Isolate;
class RegExpMatchInfo;
class RegExpStack;
template <typename T>
class Handle;
} // namespace internal
} // namespace v8
#define V8_WARN_UNUSED_RESULT [[nodiscard]]
#define V8_EXPORT_PRIVATE
#define V8_FALLTHROUGH [[fallthrough]]
#define V8_NODISCARD [[nodiscard]]
#define V8_NOEXCEPT noexcept
#define FATAL(x) MOZ_CRASH(x)
#define UNREACHABLE() MOZ_CRASH("unreachable code")
#define UNIMPLEMENTED() MOZ_CRASH("unimplemented code")
#define STATIC_ASSERT(exp) static_assert(exp, #exp)
#define DCHECK MOZ_ASSERT
#define DCHECK_EQ(lhs, rhs) MOZ_ASSERT((lhs) == (rhs))
#define DCHECK_NE(lhs, rhs) MOZ_ASSERT((lhs) != (rhs))
#define DCHECK_GT(lhs, rhs) MOZ_ASSERT((lhs) > (rhs))
#define DCHECK_GE(lhs, rhs) MOZ_ASSERT((lhs) >= (rhs))
#define DCHECK_LT(lhs, rhs) MOZ_ASSERT((lhs) < (rhs))
#define DCHECK_LE(lhs, rhs) MOZ_ASSERT((lhs) <= (rhs))
#define DCHECK_NULL(val) MOZ_ASSERT((val) == nullptr)
#define DCHECK_NOT_NULL(val) MOZ_ASSERT((val) != nullptr)
#define DCHECK_IMPLIES(lhs, rhs) MOZ_ASSERT_IF(lhs, rhs)
#define CHECK MOZ_RELEASE_ASSERT
#define CHECK_EQ(lhs, rhs) MOZ_RELEASE_ASSERT((lhs) == (rhs))
#define CHECK_LE(lhs, rhs) MOZ_RELEASE_ASSERT((lhs) <= (rhs))
#define CHECK_GE(lhs, rhs) MOZ_RELEASE_ASSERT((lhs) >= (rhs))
#define CONSTEXPR_DCHECK MOZ_ASSERT
#define MemCopy memcpy
// Origin:
// ptrdiff_t is 't' according to the standard, but MSVC uses 'I'.
#ifdef _MSC_VER
# define V8PRIxPTRDIFF "Ix"
# define V8PRIdPTRDIFF "Id"
# define V8PRIuPTRDIFF "Iu"
#else
# define V8PRIxPTRDIFF "tx"
# define V8PRIdPTRDIFF "td"
# define V8PRIuPTRDIFF "tu"
#endif
#define arraysize std::size
// Explicitly declare the assignment operator as deleted.
#define DISALLOW_ASSIGN(TypeName) TypeName& operator=(const TypeName&) = delete
// Explicitly declare the copy constructor and assignment operator as deleted.
// This also deletes the implicit move constructor and implicit move assignment
// operator, but still allows to manually define them.
#define DISALLOW_COPY_AND_ASSIGN(TypeName) \
TypeName(const TypeName&) = delete; \
DISALLOW_ASSIGN(TypeName)
// Explicitly declare all implicit constructors as deleted, namely the
// default constructor, copy constructor and operator= functions.
// This is especially useful for classes containing only static methods.
#define DISALLOW_IMPLICIT_CONSTRUCTORS(TypeName) \
TypeName() = delete; \
DISALLOW_COPY_AND_ASSIGN(TypeName)
namespace v8 {
// Origin:
template <typename T, typename U>
constexpr inline bool IsAligned(T value, U alignment) {
return (value & (alignment - 1)) == 0;
}
using Address = uintptr_t;
static const Address kNullAddress = 0;
inline uintptr_t GetCurrentStackPosition() {
return reinterpret_cast<uintptr_t>(__builtin_frame_address(0));
}
namespace base {
// Latin1/UTF-16 constants
// Code-point values in Unicode 4.0 are 21 bits wide.
// Code units in UTF-16 are 16 bits wide.
using uc16 = char16_t;
using uc32 = uint32_t;
constexpr int kUC16Size = sizeof(base::uc16);
// Origin:
// The USE(x, ...) template is used to silence C++ compiler warnings
// issued for (yet) unused variables (typically parameters).
// The arguments are guaranteed to be evaluated from left to right.
struct Use {
template <typename T>
Use(T&&) {} // NOLINT(runtime/explicit)
};
#define USE(...) \
do { \
::v8::base::Use unused_tmp_array_for_use_macro[]{__VA_ARGS__}; \
(void)unused_tmp_array_for_use_macro; \
} while (false)
// Origin:
// saturated_cast<> is analogous to static_cast<> for numeric types, except
// that the specified numeric conversion will saturate rather than overflow or
// underflow.
template <typename Dst, typename Src>
inline Dst saturated_cast(Src value);
// This is the only specialization that is needed for regexp code.
// Instead of pulling in dozens of lines of template goo
// to derive it, I used the implementation from uint8_clamped in
// ArrayBufferObject.h.
template <>
inline uint8_t saturated_cast<uint8_t, int>(int x) {
return (x >= 0) ? ((x < 255) ? uint8_t(x) : 255) : 0;
}
// Origin:
// Checks if value is in range [lower_limit, higher_limit] using a single
// branch.
template <typename T, typename U>
inline constexpr bool IsInRange(T value, U lower_limit, U higher_limit) {
using unsigned_T = typename std::make_unsigned<T>::type;
// Use static_cast to support enum classes.
return static_cast<unsigned_T>(static_cast<unsigned_T>(value) -
static_cast<unsigned_T>(lower_limit)) <=
static_cast<unsigned_T>(static_cast<unsigned_T>(higher_limit) -
static_cast<unsigned_T>(lower_limit));
}
#define LAZY_INSTANCE_INITIALIZER \
{}
template <typename T>
class LazyInstanceImpl {
public:
LazyInstanceImpl() : value_(js::mutexid::IrregexpLazyStatic) {}
const T* Pointer() {
auto val = value_.lock();
if (val->isNothing()) {
val->emplace();
}
return val->ptr();
}
private:
js::ExclusiveData<mozilla::Maybe<T>> value_;
};
template <typename T>
class LazyInstance {
public:
using type = LazyInstanceImpl<T>;
};
// Origin:
// Returns the value (0 .. 15) of a hexadecimal character c.
// If c is not a legal hexadecimal character, returns a value < 0.
// Used in regexp-parser.cc
inline int HexValue(base::uc32 c) {
c -= '0';
if (static_cast<unsigned>(c) <= 9) return c;
c = (c | 0x20) - ('a' - '0'); // detect 0x11..0x16 and 0x31..0x36.
if (static_cast<unsigned>(c) <= 5) return c + 10;
return -1;
}
template <typename... Args>
[[nodiscard]] uint32_t hash_combine(uint32_t aHash, Args... aArgs) {
return mozilla::AddToHash(aHash, aArgs...);
}
template <typename T>
class Optional {
mozilla::Maybe<T> inner_;
public:
Optional() = default;
Optional(T t) { inner_.emplace(t); }
bool has_value() const { return inner_.isSome(); }
const T& value() const { return inner_.ref(); }
};
namespace bits {
inline uint64_t CountTrailingZeros(uint64_t value) {
return mozilla::CountTrailingZeroes64(value);
}
inline size_t RoundUpToPowerOfTwo32(size_t value) {
return mozilla::RoundUpPow2(value);
}
template <typename T>
constexpr bool IsPowerOfTwo(T value) {
return value > 0 && (value & (value - 1)) == 0;
}
} // namespace bits
} // namespace base
namespace unibrow {
using uchar = unsigned int;
// Origin:
class Latin1 {
public:
static const base::uc16 kMaxChar = 0xff;
// Convert the character to Latin-1 case equivalent if possible.
static inline base::uc16 TryConvertToLatin1(base::uc16 c) {
// "GREEK CAPITAL LETTER MU" case maps to "MICRO SIGN".
// "GREEK SMALL LETTER MU" case maps to "MICRO SIGN".
if (c == 0x039C || c == 0x03BC) {
return 0xB5;
}
// "LATIN CAPITAL LETTER Y WITH DIAERESIS" case maps to "LATIN SMALL LETTER
// Y WITH DIAERESIS".
if (c == 0x0178) {
return 0xFF;
}
return c;
}
};
// Origin:
class Utf16 {
public:
static inline bool IsLeadSurrogate(int code) {
return js::unicode::IsLeadSurrogate(code);
}
static inline bool IsTrailSurrogate(int code) {
return js::unicode::IsTrailSurrogate(code);
}
static inline base::uc16 LeadSurrogate(uint32_t char_code) {
return js::unicode::LeadSurrogate(char_code);
}
static inline base::uc16 TrailSurrogate(uint32_t char_code) {
return js::unicode::TrailSurrogate(char_code);
}
static inline uint32_t CombineSurrogatePair(char16_t lead, char16_t trail) {
return js::unicode::UTF16Decode(lead, trail);
}
static const uchar kMaxNonSurrogateCharCode = 0xffff;
};
#ifndef V8_INTL_SUPPORT
// A cache used in case conversion. It caches the value for characters
// that either have no mapping or map to a single character independent
// of context. Characters that map to more than one character or that
// map differently depending on context are always looked up.
// Origin:
template <class T, int size = 256>
class Mapping {
public:
inline Mapping() = default;
inline int get(uchar c, uchar n, uchar* result) {
CacheEntry entry = entries_[c & kMask];
if (entry.code_point_ == c) {
if (entry.offset_ == 0) {
return 0;
} else {
result[0] = c + entry.offset_;
return 1;
}
} else {
return CalculateValue(c, n, result);
}
}
private:
int CalculateValue(uchar c, uchar n, uchar* result) {
bool allow_caching = true;
int length = T::Convert(c, n, result, &allow_caching);
if (allow_caching) {
if (length == 1) {
entries_[c & kMask] = CacheEntry(c, result[0] - c);
return 1;
} else {
entries_[c & kMask] = CacheEntry(c, 0);
return 0;
}
} else {
return length;
}
}
struct CacheEntry {
inline CacheEntry() : code_point_(kNoChar), offset_(0) {}
inline CacheEntry(uchar code_point, signed offset)
: code_point_(code_point), offset_(offset) {}
uchar code_point_;
signed offset_;
static const int kNoChar = (1 << 21) - 1;
};
static const int kSize = size;
static const int kMask = kSize - 1;
CacheEntry entries_[kSize];
};
// Origin:
struct Ecma262Canonicalize {
static const int kMaxWidth = 1;
static int Convert(uchar c, uchar n, uchar* result, bool* allow_caching_ptr);
};
struct Ecma262UnCanonicalize {
static const int kMaxWidth = 4;
static int Convert(uchar c, uchar n, uchar* result, bool* allow_caching_ptr);
};
struct CanonicalizationRange {
static const int kMaxWidth = 1;
static int Convert(uchar c, uchar n, uchar* result, bool* allow_caching_ptr);
};
#endif // !V8_INTL_SUPPORT
struct Letter {
static bool Is(uchar c);
};
} // namespace unibrow
namespace internal {
#define PRINTF_FORMAT(x, y) MOZ_FORMAT_PRINTF(x, y)
void PRINTF_FORMAT(1, 2) PrintF(const char* format, ...);
void PRINTF_FORMAT(2, 3) PrintF(FILE* out, const char* format, ...);
// Superclass for classes only using static method functions.
// The subclass of AllStatic cannot be instantiated at all.
class AllStatic {
#ifdef DEBUG
public:
AllStatic() = delete;
#endif
};
// Superclass for classes managed with new and delete.
// In irregexp, this is only AlternativeGeneration (in regexp-compiler.cc)
// Compare:
class Malloced {
public:
static void* operator new(size_t size) {
js::AutoEnterOOMUnsafeRegion oomUnsafe;
void* result = js_malloc(size);
if (!result) {
oomUnsafe.crash("Irregexp Malloced shim");
}
return result;
}
static void operator delete(void* p) { js_free(p); }
};
constexpr int32_t KB = 1024;
constexpr int32_t MB = 1024 * 1024;
#define kMaxInt JSVAL_INT_MAX
#define kMinInt JSVAL_INT_MIN
constexpr int kSystemPointerSize = sizeof(void*);
// The largest integer n such that n and n + 1 are both exactly
// representable as a Number value. ES6 section 20.1.2.6
constexpr double kMaxSafeInteger = 9007199254740991.0; // 2^53-1
constexpr int kBitsPerByte = 8;
constexpr int kBitsPerByteLog2 = 3;
constexpr int kUInt16Size = sizeof(uint16_t);
constexpr int kUInt32Size = sizeof(uint32_t);
constexpr int kInt64Size = sizeof(int64_t);
constexpr int kMaxUInt16 = (1 << 16) - 1;
inline constexpr bool IsDecimalDigit(base::uc32 c) {
return c >= '0' && c <= '9';
}
inline constexpr int AsciiAlphaToLower(base::uc32 c) { return c | 0x20; }
inline bool is_uint24(int64_t val) { return (val >> 24) == 0; }
inline bool is_int24(int64_t val) {
int64_t limit = int64_t(1) << 23;
return (-limit <= val) && (val < limit);
}
inline bool IsIdentifierStart(base::uc32 c) {
return js::unicode::IsIdentifierStart(char32_t(c));
}
inline bool IsIdentifierPart(base::uc32 c) {
return js::unicode::IsIdentifierPart(char32_t(c));
}
// Wrappers to disambiguate char16_t and uc16.
struct AsUC16 {
explicit AsUC16(char16_t v) : value(v) {}
char16_t value;
};
struct AsUC32 {
explicit AsUC32(int32_t v) : value(v) {}
int32_t value;
};
std::ostream& operator<<(std::ostream& os, const AsUC16& c);
std::ostream& operator<<(std::ostream& os, const AsUC32& c);
// This class is used for the output of trace-regexp-parser. V8 has
// an elaborate implementation to ensure that the output gets to the
// right place, even on Android. We just need something that will
// print output (ideally to stderr, to match the rest of our tracing
// code). This is an empty wrapper that will convert itself to
// std::cerr when used.
class StdoutStream {
public:
operator std::ostream&() const;
template <typename T>
std::ostream& operator<<(T t);
};
// Reuse existing Maybe implementation
using mozilla::Maybe;
template <typename T>
Maybe<T> Just(const T& value) {
return mozilla::Some(value);
}
template <typename T>
mozilla::Nothing Nothing() {
return mozilla::Nothing();
}
template <typename T>
using PseudoHandle = mozilla::UniquePtr<T, JS::FreePolicy>;
// Compare 8bit/16bit chars to 8bit/16bit chars.
// Used indirectly by regexp-interpreter.cc
template <typename lchar, typename rchar>
inline int CompareCharsUnsigned(const lchar* lhs, const rchar* rhs,
size_t chars) {
const lchar* limit = lhs + chars;
if (sizeof(*lhs) == sizeof(char) && sizeof(*rhs) == sizeof(char)) {
// memcmp compares byte-by-byte, yielding wrong results for two-byte
// strings on little-endian systems.
return memcmp(lhs, rhs, chars);
}
while (lhs < limit) {
int r = static_cast<int>(*lhs) - static_cast<int>(*rhs);
if (r != 0) return r;
++lhs;
++rhs;
}
return 0;
}
template <typename lchar, typename rchar>
inline int CompareChars(const lchar* lhs, const rchar* rhs, size_t chars) {
DCHECK_LE(sizeof(lchar), 2);
DCHECK_LE(sizeof(rchar), 2);
if (sizeof(lchar) == 1) {
if (sizeof(rchar) == 1) {
return CompareCharsUnsigned(reinterpret_cast<const uint8_t*>(lhs),
reinterpret_cast<const uint8_t*>(rhs), chars);
} else {
return CompareCharsUnsigned(reinterpret_cast<const uint8_t*>(lhs),
reinterpret_cast<const char16_t*>(rhs),
chars);
}
} else {
if (sizeof(rchar) == 1) {
return CompareCharsUnsigned(reinterpret_cast<const char16_t*>(lhs),
reinterpret_cast<const uint8_t*>(rhs), chars);
} else {
return CompareCharsUnsigned(reinterpret_cast<const char16_t*>(lhs),
reinterpret_cast<const char16_t*>(rhs),
chars);
}
}
}
// Compare 8bit/16bit chars to 8bit/16bit chars.
template <typename lchar, typename rchar>
inline bool CompareCharsEqualUnsigned(const lchar* lhs, const rchar* rhs,
size_t chars) {
STATIC_ASSERT(std::is_unsigned<lchar>::value);
STATIC_ASSERT(std::is_unsigned<rchar>::value);
if (sizeof(*lhs) == sizeof(*rhs)) {
// memcmp compares byte-by-byte, but for equality it doesn't matter whether
// two-byte char comparison is little- or big-endian.
return memcmp(lhs, rhs, chars * sizeof(*lhs)) == 0;
}
for (const lchar* limit = lhs + chars; lhs < limit; ++lhs, ++rhs) {
if (*lhs != *rhs) return false;
}
return true;
}
template <typename lchar, typename rchar>
inline bool CompareCharsEqual(const lchar* lhs, const rchar* rhs,
size_t chars) {
using ulchar = typename std::make_unsigned<lchar>::type;
using urchar = typename std::make_unsigned<rchar>::type;
return CompareCharsEqualUnsigned(reinterpret_cast<const ulchar*>(lhs),
reinterpret_cast<const urchar*>(rhs), chars);
}
// V8::Object ~= JS::Value
class Object {
public:
// The default object constructor in V8 stores a nullptr,
// which has its low bit clear and is interpreted as Smi(0).
constexpr Object() : asBits_(JS::Int32Value(0).asRawBits()) {}
Object(const JS::Value& value) : asBits_(value.asRawBits()) {}
// This constructor is only used in an unused implementation of
// IsCharacterInRangeArray in regexp-macro-assembler.cc.
Object(uintptr_t raw) : asBits_(raw) { MOZ_CRASH("unused"); }
JS::Value value() const { return JS::Value::fromRawBits(asBits_); }
inline static Object cast(Object object) { return object; }
protected:
void setValue(const JS::Value& val) { asBits_ = val.asRawBits(); }
uint64_t asBits_;
} JS_HAZ_GC_POINTER;
// Used in regexp-interpreter.cc to check the return value of
// isolate->stack_guard()->HandleInterrupts(). We want to handle
// interrupts in the caller, so we return a magic value from
// HandleInterrupts and check for it here.
inline bool IsException(Object obj, Isolate*) {
return obj.value().isMagic(JS_INTERRUPT_REGEXP);
}
class Smi : public Object {
public:
static Smi FromInt(int32_t value) {
Smi smi;
smi.setValue(JS::Int32Value(value));
return smi;
}
static inline int32_t ToInt(const Object object) {
return object.value().toInt32();
}
};
// V8::HeapObject ~= GC thing
class HeapObject : public Object {
public:
inline static HeapObject cast(Object object) {
HeapObject h;
h.setValue(object.value());
return h;
}
};
// V8's values use low-bit tagging. If the LSB is 0, it's a small
// integer. If the LSB is 1, it's a pointer to some GC thing. In V8,
// this wrapper class is used to represent a pointer that has the low
// bit set, or a small integer that has been shifted left by one
// bit. We don't use the same tagging system, so all we need is a
// transparent wrapper that automatically converts to/from the wrapped
// type.
template <typename T>
class Tagged {
public:
Tagged() {}
MOZ_IMPLICIT Tagged(const T& value) : value_(value) {}
MOZ_IMPLICIT Tagged(T&& value) : value_(std::move(value)) {}
T* operator->() { return &value_; }
constexpr operator T() const { return value_; }
private:
T value_;
};
// A fixed-size array with Objects (aka Values) as element types.
// Implemented using the dense elements of an ArrayObject.
// Used for named captures.
class FixedArray : public HeapObject {
public:
inline void set(uint32_t index, Object value) {
inner()->setDenseElement(index, value.value());
}
inline static FixedArray cast(Object object) {
FixedArray f;
f.setValue(object.value());
return f;
}
js::NativeObject* inner() {
return &value().toObject().as<js::NativeObject>();
}
};
/*
* Conceptually, ByteArrayData is a variable-size structure. To
* implement this in a C++-approved way, we allocate a struct
* containing the 32-bit length field, followed by additional memory
* for the data. To access the data, we get a pointer to the next byte
* after the length field and cast it to the correct type.
*/
inline uint8_t* ByteArrayData::data() {
static_assert(alignof(uint8_t) <= alignof(ByteArrayData),
"The trailing data must be aligned to start immediately "
"after the header with no padding.");
ByteArrayData* immediatelyAfter = this + 1;
return reinterpret_cast<uint8_t*>(immediatelyAfter);
}
template <typename T>
T* ByteArrayData::typedData() {
static_assert(alignof(T) <= alignof(ByteArrayData));
MOZ_ASSERT(uintptr_t(data()) % alignof(T) == 0);
return reinterpret_cast<T*>(data());
}
template <typename T>
T ByteArrayData::getTyped(uint32_t index) {
MOZ_ASSERT(index < length() / sizeof(T));
return typedData<T>()[index];
}
template <typename T>
void ByteArrayData::setTyped(uint32_t index, T value) {
MOZ_ASSERT(index < length() / sizeof(T));
typedData<T>()[index] = value;
}
// A fixed-size array of bytes.
class ByteArray : public HeapObject {
protected:
ByteArrayData* inner() const {
return static_cast<ByteArrayData*>(value().toPrivate());
}
friend bool IsByteArray(Object obj);
public:
PseudoHandle<ByteArrayData> takeOwnership(Isolate* isolate);
PseudoHandle<ByteArrayData> maybeTakeOwnership(Isolate* isolate);
uint8_t get(uint32_t index) { return inner()->get(index); }
void set(uint32_t index, uint8_t val) { inner()->set(index, val); }
uint32_t length() const { return inner()->length(); }
uint8_t* begin() { return inner()->data(); }
static ByteArray cast(Object object) {
ByteArray b;
b.setValue(object.value());
return b;
}
friend class SMRegExpMacroAssembler;
};
// This is only used in assertions. In debug builds, we put a magic value
// in the header of each ByteArrayData, and assert here that it matches.
inline bool IsByteArray(Object obj) {
MOZ_ASSERT(ByteArray::cast(obj).inner()->magic() ==
ByteArrayData::ExpectedMagic);
return true;
}
// This is a convenience class used in V8 for treating a ByteArray as an array
// of fixed-size integers. This version supports integral types up to 32 bits.
template <typename T>
class FixedIntegerArray : public ByteArray {
static_assert(alignof(T) <= alignof(ByteArrayData));
static_assert(std::is_integral<T>::value);
public:
static Handle<FixedIntegerArray<T>> New(Isolate* isolate, uint32_t length);
T get(uint32_t index) { return inner()->template getTyped<T>(index); };
void set(uint32_t index, T value) {
inner()->template setTyped<T>(index, value);
}
static FixedIntegerArray<T> cast(Object object) {
FixedIntegerArray<T> f;
f.setValue(object.value());
return f;
}
};
using FixedUInt16Array = FixedIntegerArray<uint16_t>;
// Like Handles in SM, V8 handles are references to marked pointers.
// Unlike SM, where Rooted pointers are created individually on the
// stack, the target of a V8 handle lives in an arena on the isolate
// (~= JSContext). Whenever a Handle is created, a new "root" is
// created at the end of the arena.
//
// HandleScopes are used to manage the lifetimes of these handles. A
// HandleScope lives on the stack and stores the size of the arena at
// the time of its creation. When the function returns and the
// HandleScope is destroyed, the arena is truncated to its previous
// size, clearing all roots that were created since the creation of
// the HandleScope.
//
// In some cases, objects that are GC-allocated in V8 are not in SM.
// In particular, irregexp allocates ByteArrays during code generation
// to store lookup tables. This does not play nicely with the SM
// macroassembler's requirement that no GC allocations take place
// while it is on the stack. To work around this, this shim layer also
// provides the ability to create pseudo-handles, which are not
// managed by the GC but provide the same API to irregexp. The "root"
// of a pseudohandle is a unique pointer living in a second arena. If
// the allocated object should outlive the HandleScope, it must be
// manually moved out of the arena using maybeTakeOwnership.
// (If maybeTakeOwnership is called multiple times, it will return
// a null pointer on subsequent calls.)
class MOZ_STACK_CLASS HandleScope {
public:
HandleScope(Isolate* isolate);
~HandleScope();
private:
size_t level_ = 0;
size_t non_gc_level_ = 0;
Isolate* isolate_;
friend class Isolate;
};
// Origin:
template <typename T>
class MOZ_NONHEAP_CLASS Handle {
public:
Handle() : location_(nullptr) {}
Handle(T object, Isolate* isolate);
Handle(const JS::Value& value, Isolate* isolate);
// Constructor for handling automatic up casting.
template <typename S,
typename = std::enable_if_t<std::is_convertible_v<S*, T*>>>
inline Handle(Handle<S> handle) : location_(handle.location_) {}
inline bool is_null() const { return location_ == nullptr; }
inline T operator*() const { return T::cast(Object(*location_)); };
// {ObjectRef} is returned by {Handle::operator->}. It should never be stored
// anywhere or used in any other code; no one should ever have to spell out
// {ObjectRef} in code. Its only purpose is to be dereferenced immediately by
// "operator-> chaining". Returning the address of the field is valid because
// this object's lifetime only ends at the end of the full statement.
// Origin:
class MOZ_TEMPORARY_CLASS ObjectRef {
public:
T* operator->() { return &object_; }
private:
friend class Handle;
explicit ObjectRef(T object) : object_(object) {}
T object_;
};
inline ObjectRef operator->() const { return ObjectRef{**this}; }
static Handle<T> fromHandleValue(JS::HandleValue handle) {
return Handle(handle.address());
}
private:
Handle(const JS::Value* location) : location_(location) {}
template <typename>
friend class Handle;
template <typename>
friend class MaybeHandle;
const JS::Value* location_;
};
// A Handle can be converted into a MaybeHandle. Converting a MaybeHandle
// into a Handle requires checking that it does not point to nullptr. This
// ensures nullptr checks before use.
//
// Also note that Handles do not provide default equality comparison or hashing
// operators on purpose. Such operators would be misleading, because intended
// semantics is ambiguous between Handle location and object identity.
// Origin:
template <typename T>
class MOZ_NONHEAP_CLASS MaybeHandle final {
public:
MaybeHandle() : location_(nullptr) {}
// Constructor for handling automatic up casting from Handle.
// Ex. Handle<JSArray> can be passed when MaybeHandle<Object> is expected.
template <typename S,
typename = std::enable_if_t<std::is_convertible_v<S*, T*>>>
MaybeHandle(Handle<S> handle) : location_(handle.location_) {}
inline Handle<T> ToHandleChecked() const {
MOZ_RELEASE_ASSERT(location_);
return Handle<T>(location_);
}
// Convert to a Handle with a type that can be upcasted to.
template <typename S>
inline bool ToHandle(Handle<S>* out) const {
if (location_) {
*out = Handle<T>(location_);
return true;
} else {
*out = Handle<T>();
return false;
}
}
private:
JS::Value* location_;
};
// From v8/src/handles/handles-inl.h
template <typename T>
inline Handle<T> handle(T object, Isolate* isolate) {
return Handle<T>(object, isolate);
}
// RAII Guard classes
using DisallowGarbageCollection = JS::AutoAssertNoGC;
// V8 uses this inside DisallowGarbageCollection regions to turn
// allocation back on before throwing a stack overflow exception or
// handling interrupts. AutoSuppressGC is sufficient for the former
// case, but not for the latter: handling interrupts can execute
// arbitrary script code, and V8 jumps through some scary hoops to
// "manually relocate unhandlified references" afterwards. To keep
// things sane, we don't try to handle interrupts while regex code is
// still on the stack. Instead, we return EXCEPTION and handle
// interrupts in the caller. (See RegExpShared::execute.)
class AllowGarbageCollection {
public:
AllowGarbageCollection() {}
};
// Origin:
class String : public HeapObject {
private:
JSString* str() const { return value().toString(); }
public:
String() = default;
String(JSString* str) { setValue(JS::StringValue(str)); }
operator JSString*() const { return str(); }
// Max char codes.
static const int32_t kMaxOneByteCharCode = unibrow::Latin1::kMaxChar;
static const uint32_t kMaxOneByteCharCodeU = unibrow::Latin1::kMaxChar;
static const int kMaxUtf16CodeUnit = 0xffff;
static const uint32_t kMaxUtf16CodeUnitU = kMaxUtf16CodeUnit;
static const base::uc32 kMaxCodePoint = 0x10ffff;
MOZ_ALWAYS_INLINE int length() const { return str()->length(); }
bool IsFlat() { return str()->isLinear(); };
// Origin:
class FlatContent {
public:
FlatContent(JSLinearString* string, const DisallowGarbageCollection& no_gc)
: string_(string), no_gc_(no_gc) {}
inline bool IsOneByte() const { return string_->hasLatin1Chars(); }
inline bool IsTwoByte() const { return !string_->hasLatin1Chars(); }
base::Vector<const uint8_t> ToOneByteVector() const {
MOZ_ASSERT(IsOneByte());
return base::Vector<const uint8_t>(string_->latin1Chars(no_gc_),
string_->length());
}
base::Vector<const base::uc16> ToUC16Vector() const {
MOZ_ASSERT(IsTwoByte());
return base::Vector<const base::uc16>(string_->twoByteChars(no_gc_),
string_->length());
}
void UnsafeDisableChecksumVerification() {
// Intentional no-op. See the comment for AllowGarbageCollection above.
}
private:
const JSLinearString* string_;
const JS::AutoAssertNoGC& no_gc_;
};
FlatContent GetFlatContent(const DisallowGarbageCollection& no_gc) {
MOZ_ASSERT(IsFlat());
return FlatContent(&str()->asLinear(), no_gc);
}
static Handle<String> Flatten(Isolate* isolate, Handle<String> string);
inline static String cast(Object object) {
String s;
MOZ_ASSERT(object.value().isString());
s.setValue(object.value());
return s;
}
inline static bool IsOneByteRepresentationUnderneath(String string) {
return string.str()->hasLatin1Chars();
}
inline bool IsOneByteRepresentation() const {
return str()->hasLatin1Chars();
}
std::unique_ptr<char[]> ToCString();
template <typename Char>
base::Vector<const Char> GetCharVector(
const DisallowGarbageCollection& no_gc);
};
template <>
inline base::Vector<const uint8_t> String::GetCharVector(
const DisallowGarbageCollection& no_gc) {
String::FlatContent flat = GetFlatContent(no_gc);
MOZ_ASSERT(flat.IsOneByte());
return flat.ToOneByteVector();
}
template <>
inline base::Vector<const base::uc16> String::GetCharVector(
const DisallowGarbageCollection& no_gc) {
String::FlatContent flat = GetFlatContent(no_gc);
MOZ_ASSERT(flat.IsTwoByte());
return flat.ToUC16Vector();
}
class JSRegExp : public HeapObject {
public:
JSRegExp() : HeapObject() {}
JSRegExp(js::RegExpShared* re) { setValue(JS::PrivateGCThingValue(re)); }
// ******************************************************
// Methods that are called from inside the implementation
// ******************************************************
void TierUpTick() { inner()->tierUpTick(); }
Object bytecode(bool is_latin1) const {
return Object(JS::PrivateValue(inner()->getByteCode(is_latin1)));
}
// TODO: should we expose this?
uint32_t backtrack_limit() const { return 0; }
static JSRegExp cast(Object object) {
JSRegExp regexp;
js::gc::Cell* regexpShared = object.value().toGCThing();
MOZ_ASSERT(regexpShared->is<js::RegExpShared>());
regexp.setValue(JS::PrivateGCThingValue(regexpShared));
return regexp;
}
// Each capture (including the match itself) needs two registers.
static constexpr int RegistersForCaptureCount(int count) {
return (count + 1) * 2;
}
inline uint32_t max_register_count() const {
return inner()->getMaxRegisters();
}
// ******************************
// Static constants
// ******************************
static constexpr int kMaxCaptures = (1 << 15) - 1;
static constexpr int kNoBacktrackLimit = 0;
private:
js::RegExpShared* inner() const {
return value().toGCThing()->as<js::RegExpShared>();
}
};
using RegExpFlags = JS::RegExpFlags;
using RegExpFlag = JS::RegExpFlags::Flag;
inline bool IsUnicode(RegExpFlags flags) { return flags.unicode(); }
inline bool IsGlobal(RegExpFlags flags) { return flags.global(); }
inline bool IsIgnoreCase(RegExpFlags flags) { return flags.ignoreCase(); }
inline bool IsMultiline(RegExpFlags flags) { return flags.multiline(); }
inline bool IsDotAll(RegExpFlags flags) { return flags.dotAll(); }
inline bool IsSticky(RegExpFlags flags) { return flags.sticky(); }
inline bool IsUnicodeSets(RegExpFlags flags) { return flags.unicodeSets(); }
inline bool IsEitherUnicode(RegExpFlags flags) {
return flags.unicode() || flags.unicodeSets();
}
inline base::Optional<RegExpFlag> TryRegExpFlagFromChar(char c) {
RegExpFlag flag;
// The parser only calls this after verifying that it's a supported flag.
MOZ_ALWAYS_TRUE(JS::MaybeParseRegExpFlag(c, &flag));
return base::Optional(flag);
}
inline bool operator==(const RegExpFlags& lhs, const int& rhs) {
return lhs.value() == rhs;
}
inline bool operator!=(const RegExpFlags& lhs, const int& rhs) {
return !(lhs == rhs);
}
class Histogram {
public:
inline void AddSample(int sample) {}
};
class Counters {
public:
Histogram* regexp_backtracks() { return &regexp_backtracks_; }
private:
Histogram regexp_backtracks_;
};
enum class AllocationType : uint8_t {
kYoung, // Allocate in the nursery
kOld, // Allocate in the tenured heap
};
using StackGuard = Isolate;
using Factory = Isolate;
class Isolate {
public:
Isolate(JSContext* cx) : cx_(cx) {}
~Isolate();
bool init();
size_t sizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const;
//********** Isolate code **********//
RegExpStack* regexp_stack() const { return regexpStack_; }
// This is called from inside no-GC code. Instead of suppressing GC
// to allocate the error, we return false from Execute and call
// ReportOverRecursed in the caller.
void StackOverflow() {}
#ifndef V8_INTL_SUPPORT
unibrow::Mapping<unibrow::Ecma262UnCanonicalize>* jsregexp_uncanonicalize() {
return &jsregexp_uncanonicalize_;
}
unibrow::Mapping<unibrow::Ecma262Canonicalize>*
regexp_macro_assembler_canonicalize() {
return &regexp_macro_assembler_canonicalize_;
}
unibrow::Mapping<unibrow::CanonicalizationRange>* jsregexp_canonrange() {
return &jsregexp_canonrange_;
}
private:
unibrow::Mapping<unibrow::Ecma262UnCanonicalize> jsregexp_uncanonicalize_;
unibrow::Mapping<unibrow::Ecma262Canonicalize>
regexp_macro_assembler_canonicalize_;
unibrow::Mapping<unibrow::CanonicalizationRange> jsregexp_canonrange_;
#endif // !V8_INTL_SUPPORT
public:
// An empty stub for telemetry we don't support
void IncreaseTotalRegexpCodeGenerated(Handle<HeapObject> code) {}
Counters* counters() { return &counters_; }
//********** Factory code **********//
inline Factory* factory() { return this; }
Handle<ByteArray> NewByteArray(
int length, AllocationType allocation = AllocationType::kYoung);
// Allocates a fixed array initialized with undefined values.
Handle<FixedArray> NewFixedArray(int length);
template <typename T>
Handle<FixedIntegerArray<T>> NewFixedIntegerArray(uint32_t length);
template <typename Char>
Handle<String> InternalizeString(const base::Vector<const Char>& str);
//********** Stack guard code **********//
inline StackGuard* stack_guard() { return this; }
uintptr_t real_climit() { return cx_->stackLimit(JS::StackForSystemCode); }
// This is called from inside no-GC code. V8 runs the interrupt
// inside the no-GC code and then "manually relocates unhandlified
// references" afterwards. We just return a magic value and let the
// caller handle interrupts.
Object HandleInterrupts() {
return Object(JS::MagicValue(JS_INTERRUPT_REGEXP));
}
JSContext* cx() const { return cx_; }
void trace(JSTracer* trc);
//********** Handle code **********//
JS::Value* getHandleLocation(const JS::Value& value);
private:
mozilla::SegmentedVector<JS::Value, 256> handleArena_;
mozilla::SegmentedVector<PseudoHandle<void>, 256> uniquePtrArena_;
void* allocatePseudoHandle(size_t bytes);
public:
template <typename T>
PseudoHandle<T> takeOwnership(void* ptr);
template <typename T>
PseudoHandle<T> maybeTakeOwnership(void* ptr);
uint32_t liveHandles() const { return handleArena_.Length(); }
uint32_t livePseudoHandles() const { return uniquePtrArena_.Length(); }
private:
void openHandleScope(HandleScope& scope) {
scope.level_ = handleArena_.Length();
scope.non_gc_level_ = uniquePtrArena_.Length();
}
void closeHandleScope(size_t prevLevel, size_t prevUniqueLevel) {
size_t currLevel = handleArena_.Length();
handleArena_.PopLastN(currLevel - prevLevel);
size_t currUniqueLevel = uniquePtrArena_.Length();
uniquePtrArena_.PopLastN(currUniqueLevel - prevUniqueLevel);
}
friend class HandleScope;
JSContext* cx_;
RegExpStack* regexpStack_{};
Counters counters_{};
#ifdef DEBUG
public:
uint32_t shouldSimulateInterrupt_ = 0;
#endif
};
// Origin:
class StackLimitCheck {
public:
StackLimitCheck(Isolate* isolate) : cx_(isolate->cx()) {}
// Use this to check for stack-overflows in C++ code.
bool HasOverflowed() {
js::AutoCheckRecursionLimit recursion(cx_);
bool overflowed = !recursion.checkDontReport(cx_);
if (overflowed && js::SupportDifferentialTesting()) {
// We don't report overrecursion here, but we throw an exception later
// and this still affects differential testing. Mimic ReportOverRecursed
// (the fuzzers check for this particular string).
fprintf(stderr, "ReportOverRecursed called\n");
}
return overflowed;
}
// Use this to check for interrupt request in C++ code.
bool InterruptRequested() {
return cx_->hasPendingInterrupt(js::InterruptReason::CallbackUrgent);
}
// Use this to check for stack-overflow when entering runtime from JS code.
bool JsHasOverflowed() {
js::AutoCheckRecursionLimit recursion(cx_);
return !recursion.checkDontReport(cx_);
}
private:
JSContext* cx_;
};
class ExternalReference {
public:
static const void* TopOfRegexpStack(Isolate* isolate);
static size_t SizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf,
RegExpStack* regexpStack);
};
class Code : public HeapObject {
public:
uint8_t* raw_instruction_start() { return inner()->raw(); }
static Code cast(Object object) {
Code c;
js::gc::Cell* jitCode = object.value().toGCThing();
MOZ_ASSERT(jitCode->is<js::jit::JitCode>());
c.setValue(JS::PrivateGCThingValue(jitCode));
return c;
}
js::jit::JitCode* inner() {
return value().toGCThing()->as<js::jit::JitCode>();
}
};
// Only used in function signature of functions we don't implement
// (NativeRegExpMacroAssembler::CheckStackGuardState)
class InstructionStream {};
class Label {
public:
Label() : inner_(js::jit::Label()) {}
js::jit::Label* inner() { return &inner_; }
void Unuse() { inner_.reset(); }
bool is_linked() { return inner_.used(); }
bool is_bound() { return inner_.bound(); }
bool is_unused() { return !inner_.used() && !inner_.bound(); }
int pos() { return inner_.offset(); }
void link_to(int pos) { inner_.use(pos); }
void bind_to(int pos) { inner_.bind(pos); }
private:
js::jit::Label inner_;
js::jit::CodeOffset patchOffset_;
friend class SMRegExpMacroAssembler;
};
#define v8_flags js::jit::JitOptions
#define V8_USE_COMPUTED_GOTO 1
#define COMPILING_IRREGEXP_FOR_EXTERNAL_EMBEDDER
} // namespace internal
} // namespace v8
namespace V8 {
inline void FatalProcessOutOfMemory(v8::internal::Isolate* isolate,
const char* msg) {
js::AutoEnterOOMUnsafeRegion oomUnsafe;
oomUnsafe.crash(msg);
}
} // namespace V8
#endif // RegexpShim_h