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// Copyright 2012 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.
#include "src/codegen/label.h"
#include "src/regexp/regexp-ast.h"
#include "src/regexp/regexp.h"
namespace v8 {
namespace internal {
static const uc32 kLeadSurrogateStart = 0xd800;
static const uc32 kLeadSurrogateEnd = 0xdbff;
static const uc32 kTrailSurrogateStart = 0xdc00;
static const uc32 kTrailSurrogateEnd = 0xdfff;
static const uc32 kNonBmpStart = 0x10000;
static const uc32 kNonBmpEnd = 0x10ffff;
struct DisjunctDecisionRow {
RegExpCharacterClass cc;
Label* on_match;
class RegExpMacroAssembler {
// The implementation must be able to handle at least:
static constexpr int kMaxRegisterCount = (1 << 16);
static constexpr int kMaxRegister = kMaxRegisterCount - 1;
static constexpr int kMaxCPOffset = (1 << 15) - 1;
static constexpr int kMinCPOffset = -(1 << 15);
static constexpr int kTableSizeBits = 7;
static constexpr int kTableSize = 1 << kTableSizeBits;
static constexpr int kTableMask = kTableSize - 1;
static constexpr int kUseCharactersValue = -1;
enum IrregexpImplementation {
enum StackCheckFlag {
kNoStackLimitCheck = false,
kCheckStackLimit = true
RegExpMacroAssembler(Isolate* isolate, Zone* zone);
virtual ~RegExpMacroAssembler();
// This function is called when code generation is aborted, so that
// the assembler could clean up internal data structures.
virtual void AbortedCodeGeneration() {}
// The maximal number of pushes between stack checks. Users must supply
// kCheckStackLimit flag to push operations (instead of kNoStackLimitCheck)
// at least once for every stack_limit() pushes that are executed.
virtual int stack_limit_slack() = 0;
virtual bool CanReadUnaligned() = 0;
virtual void AdvanceCurrentPosition(int by) = 0; // Signed cp change.
virtual void AdvanceRegister(int reg, int by) = 0; // r[reg] += by.
// Continues execution from the position pushed on the top of the backtrack
// stack by an earlier PushBacktrack(Label*).
virtual void Backtrack() = 0;
virtual void Bind(Label* label) = 0;
// Dispatch after looking the current character up in a 2-bits-per-entry
// map. The destinations vector has up to 4 labels.
virtual void CheckCharacter(unsigned c, Label* on_equal) = 0;
// Bitwise and the current character with the given constant and then
// check for a match with c.
virtual void CheckCharacterAfterAnd(unsigned c,
unsigned and_with,
Label* on_equal) = 0;
virtual void CheckCharacterGT(uc16 limit, Label* on_greater) = 0;
virtual void CheckCharacterLT(uc16 limit, Label* on_less) = 0;
virtual void CheckGreedyLoop(Label* on_tos_equals_current_position) = 0;
virtual void CheckAtStart(int cp_offset, Label* on_at_start) = 0;
virtual void CheckNotAtStart(int cp_offset, Label* on_not_at_start) = 0;
virtual void CheckNotBackReference(int start_reg, bool read_backward,
Label* on_no_match) = 0;
virtual void CheckNotBackReferenceIgnoreCase(int start_reg,
bool read_backward, bool unicode,
Label* on_no_match) = 0;
// Check the current character for a match with a literal character. If we
// fail to match then goto the on_failure label. End of input always
// matches. If the label is nullptr then we should pop a backtrack address
// off the stack and go to that.
virtual void CheckNotCharacter(unsigned c, Label* on_not_equal) = 0;
virtual void CheckNotCharacterAfterAnd(unsigned c,
unsigned and_with,
Label* on_not_equal) = 0;
// Subtract a constant from the current character, then and with the given
// constant and then check for a match with c.
virtual void CheckNotCharacterAfterMinusAnd(uc16 c,
uc16 minus,
uc16 and_with,
Label* on_not_equal) = 0;
virtual void CheckCharacterInRange(uc16 from,
uc16 to, // Both inclusive.
Label* on_in_range) = 0;
virtual void CheckCharacterNotInRange(uc16 from,
uc16 to, // Both inclusive.
Label* on_not_in_range) = 0;
// The current character (modulus the kTableSize) is looked up in the byte
// array, and if the found byte is non-zero, we jump to the on_bit_set label.
virtual void CheckBitInTable(Handle<ByteArray> table, Label* on_bit_set) = 0;
// Checks whether the given offset from the current position is before
// the end of the string. May overwrite the current character.
virtual void CheckPosition(int cp_offset, Label* on_outside_input);
// Check whether a standard/default character class matches the current
// character. Returns false if the type of special character class does
// not have custom support.
// May clobber the current loaded character.
virtual bool CheckSpecialCharacterClass(uc16 type, Label* on_no_match);
// Control-flow integrity:
// Define a jump target and bind a label.
virtual void BindJumpTarget(Label* label) { Bind(label); }
virtual void Fail() = 0;
virtual Handle<HeapObject> GetCode(Handle<String> source) = 0;
virtual void GoTo(Label* label) = 0;
// Check whether a register is >= a given constant and go to a label if it
// is. Backtracks instead if the label is nullptr.
virtual void IfRegisterGE(int reg, int comparand, Label* if_ge) = 0;
// Check whether a register is < a given constant and go to a label if it is.
// Backtracks instead if the label is nullptr.
virtual void IfRegisterLT(int reg, int comparand, Label* if_lt) = 0;
// Check whether a register is == to the current position and go to a
// label if it is.
virtual void IfRegisterEqPos(int reg, Label* if_eq) = 0;
virtual IrregexpImplementation Implementation() = 0;
V8_EXPORT_PRIVATE void LoadCurrentCharacter(
int cp_offset, Label* on_end_of_input, bool check_bounds = true,
int characters = 1, int eats_at_least = kUseCharactersValue);
virtual void LoadCurrentCharacterImpl(int cp_offset, Label* on_end_of_input,
bool check_bounds, int characters,
int eats_at_least) = 0;
virtual void PopCurrentPosition() = 0;
virtual void PopRegister(int register_index) = 0;
// Pushes the label on the backtrack stack, so that a following Backtrack
// will go to this label. Always checks the backtrack stack limit.
virtual void PushBacktrack(Label* label) = 0;
virtual void PushCurrentPosition() = 0;
virtual void PushRegister(int register_index,
StackCheckFlag check_stack_limit) = 0;
virtual void ReadCurrentPositionFromRegister(int reg) = 0;
virtual void ReadStackPointerFromRegister(int reg) = 0;
virtual void SetCurrentPositionFromEnd(int by) = 0;
virtual void SetRegister(int register_index, int to) = 0;
// Return whether the matching (with a global regexp) will be restarted.
virtual bool Succeed() = 0;
virtual void WriteCurrentPositionToRegister(int reg, int cp_offset) = 0;
virtual void ClearRegisters(int reg_from, int reg_to) = 0;
virtual void WriteStackPointerToRegister(int reg) = 0;
// Compare two-byte strings case insensitively.
// Called from generated RegExp code.
static int CaseInsensitiveCompareNonUnicode(Address byte_offset1,
Address byte_offset2,
size_t byte_length,
Isolate* isolate);
static int CaseInsensitiveCompareUnicode(Address byte_offset1,
Address byte_offset2,
size_t byte_length,
Isolate* isolate);
// Check that we are not in the middle of a surrogate pair.
void CheckNotInSurrogatePair(int cp_offset, Label* on_failure);
// Controls the generation of large inlined constants in the code.
void set_slow_safe(bool ssc) { slow_safe_compiler_ = ssc; }
bool slow_safe() { return slow_safe_compiler_; }
// Controls after how many backtracks irregexp should abort execution. If it
// can fall back to the experimental engine (see `set_can_fallback`), it will
// return the appropriate error code, otherwise it will return the number of
// matches found so far (perhaps none).
void set_backtrack_limit(uint32_t backtrack_limit) {
backtrack_limit_ = backtrack_limit;
// Set whether or not irregexp can fall back to the experimental engine on
// excessive backtracking. The number of backtracks considered excessive can
// be controlled with set_backtrack_limit.
void set_can_fallback(bool val) { can_fallback_ = val; }
enum GlobalMode {
// Set whether the regular expression has the global flag. Exiting due to
// a failure in a global regexp may still mean success overall.
inline void set_global_mode(GlobalMode mode) { global_mode_ = mode; }
inline bool global() { return global_mode_ != NOT_GLOBAL; }
inline bool global_with_zero_length_check() {
return global_mode_ == GLOBAL || global_mode_ == GLOBAL_UNICODE;
inline bool global_unicode() { return global_mode_ == GLOBAL_UNICODE; }
Isolate* isolate() const { return isolate_; }
Zone* zone() const { return zone_; }
bool has_backtrack_limit() const {
return backtrack_limit_ != JSRegExp::kNoBacktrackLimit;
uint32_t backtrack_limit() const { return backtrack_limit_; }
bool can_fallback() const { return can_fallback_; }
bool slow_safe_compiler_;
uint32_t backtrack_limit_ = JSRegExp::kNoBacktrackLimit;
bool can_fallback_ = false;
GlobalMode global_mode_;
Isolate* isolate_;
Zone* zone_;
class NativeRegExpMacroAssembler: public RegExpMacroAssembler {
// Type of input string to generate code for.
enum Mode { LATIN1 = 1, UC16 = 2 };
// Result of calling generated native RegExp code.
// RETRY: Something significant changed during execution, and the matching
// should be retried from scratch.
// EXCEPTION: Something failed during execution. If no exception has been
// thrown, it's an internal out-of-memory, and the caller should
// throw the exception.
// FAILURE: Matching failed.
// SUCCESS: Matching succeeded, and the output array has been filled with
// capture positions.
// FALLBACK_TO_EXPERIMENTAL: Execute the regexp on this subject using the
// experimental engine instead.
enum Result {
FAILURE = RegExp::kInternalRegExpFailure,
SUCCESS = RegExp::kInternalRegExpSuccess,
EXCEPTION = RegExp::kInternalRegExpException,
RETRY = RegExp::kInternalRegExpRetry,
FALLBACK_TO_EXPERIMENTAL = RegExp::kInternalRegExpFallbackToExperimental,
SMALLEST_REGEXP_RESULT = RegExp::kInternalRegExpSmallestResult,
NativeRegExpMacroAssembler(Isolate* isolate, Zone* zone);
~NativeRegExpMacroAssembler() override;
bool CanReadUnaligned() override;
// Returns a {Result} sentinel, or the number of successful matches.
static int Match(Handle<JSRegExp> regexp, Handle<String> subject,
int* offsets_vector, int offsets_vector_length,
int previous_index, Isolate* isolate);
// Called from RegExp if the backtrack stack limit is hit.
// Tries to expand the stack. Returns the new stack-pointer if
// successful, and updates the stack_top address, or returns 0 if unable
// to grow the stack.
// This function must not trigger a garbage collection.
static Address GrowStack(Address stack_pointer, Address* stack_top,
Isolate* isolate);
static int CheckStackGuardState(Isolate* isolate, int start_index,
RegExp::CallOrigin call_origin,
Address* return_address, Code re_code,
Address* subject, const byte** input_start,
const byte** input_end);
// Byte map of one byte characters with a 0xff if the character is a word
// character (digit, letter or underscore) and 0x00 otherwise.
// Used by generated RegExp code.
static const byte word_character_map[256];
static Address word_character_map_address() {
return reinterpret_cast<Address>(&word_character_map[0]);
// Returns a {Result} sentinel, or the number of successful matches.
V8_EXPORT_PRIVATE static int Execute(String input, int start_offset,
const byte* input_start,
const byte* input_end, int* output,
int output_size, Isolate* isolate,
JSRegExp regexp);
void LoadCurrentCharacterImpl(int cp_offset, Label* on_end_of_input,
bool check_bounds, int characters,
int eats_at_least) override;
// Load a number of characters at the given offset from the
// current position, into the current-character register.
virtual void LoadCurrentCharacterUnchecked(int cp_offset,
int character_count) = 0;
} // namespace internal
} // namespace v8