src/regexp-macro-assembler.h

// Copyright 2008 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
//       copyright notice, this list of conditions and the following
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//       with the distribution.
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#ifndef V8_REGEXP_MACRO_ASSEMBLER_H_
#define V8_REGEXP_MACRO_ASSEMBLER_H_

#include "ast.h"

namespace v8 {
namespace internal {

struct DisjunctDecisionRow {
  RegExpCharacterClass cc;
  Label* on_match;
};


class RegExpMacroAssembler {
 public:
  // The implementation must be able to handle at least:
  static const int kMaxRegister = (1 << 16) - 1;
  static const int kMaxCPOffset = (1 << 15) - 1;
  static const int kMinCPOffset = -(1 << 15);
  enum IrregexpImplementation {
    kIA32Implementation,
    kARMImplementation,
    kX64Implementation,
    kBytecodeImplementation
  };

  enum StackCheckFlag {
    kNoStackLimitCheck = false,
    kCheckStackLimit = true
  };

  RegExpMacroAssembler();
  virtual ~RegExpMacroAssembler();
  // 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();
  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;
  virtual void CheckAtStart(Label* on_at_start) = 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;
  // Check the current character for a match with a literal string.  If we
  // fail to match then goto the on_failure label.  If check_eos is set then
  // the end of input always fails.  If check_eos is clear then it is the
  // caller's responsibility to ensure that the end of string is not hit.
  // If the label is NULL then we should pop a backtrack address off
  // the stack and go to that.
  virtual void CheckCharacters(
      Vector<const uc16> str,
      int cp_offset,
      Label* on_failure,
      bool check_eos) = 0;
  virtual void CheckGreedyLoop(Label* on_tos_equals_current_position) = 0;
  virtual void CheckNotAtStart(Label* on_not_at_start) = 0;
  virtual void CheckNotBackReference(int start_reg, Label* on_no_match) = 0;
  virtual void CheckNotBackReferenceIgnoreCase(int start_reg,
                                               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 NULL 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 or 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 CheckNotRegistersEqual(int reg1,
                                      int reg2,
                                      Label* on_not_equal) = 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) {
    LoadCurrentCharacter(cp_offset, on_outside_input, true);
  }
  // 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) {
    return false;
  }
  virtual void Fail() = 0;
  virtual Handle<Object> 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 NULL.
  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 NULL.
  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;
  virtual void LoadCurrentCharacter(int cp_offset,
                                    Label* on_end_of_input,
                                    bool check_bounds = true,
                                    int characters = 1) = 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;
  virtual void 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;
};


#ifndef V8_INTERPRETED_REGEXP  // Avoid compiling unused code.

class NativeRegExpMacroAssembler: public RegExpMacroAssembler {
 public:
  // Type of input string to generate code for.
  enum Mode { ASCII = 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.
  enum Result { RETRY = -2, EXCEPTION = -1, FAILURE = 0, SUCCESS = 1 };

  NativeRegExpMacroAssembler();
  virtual ~NativeRegExpMacroAssembler();
  virtual bool CanReadUnaligned();

  static Result Match(Handle<Code> regexp,
                      Handle<String> subject,
                      int* offsets_vector,
                      int offsets_vector_length,
                      int previous_index);

  // Compares two-byte strings case insensitively.
  // Called from generated RegExp code.
  static int CaseInsensitiveCompareUC16(Address byte_offset1,
                                        Address byte_offset2,
                                        size_t byte_length);

  // 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);

  static const byte* StringCharacterPosition(String* subject, int start_index);

  // Byte map of ASCII characters with a 0xff if the character is a word
  // character (digit, letter or underscore) and 0x00 otherwise.
  // Used by generated RegExp code.
  static byte word_character_map[128];

  static Address word_character_map_address() {
    return &word_character_map[0];
  }

  static Result Execute(Code* code,
                        String* input,
                        int start_offset,
                        const byte* input_start,
                        const byte* input_end,
                        int* output);
};

#endif  // V8_INTERPRETED_REGEXP

} }  // namespace v8::internal

#endif  // V8_REGEXP_MACRO_ASSEMBLER_H_