text: // Copyright 2008-2009 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
  //       disclaimer in the documentation and/or other materials provided
  //       with the distribution.
  //     * Neither the name of Google Inc. nor the names of its
  //       contributors may be used to endorse or promote products derived
  //       from this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  #include "v8.h"
  
  #if defined(V8_TARGET_ARCH_IA32)
  
  #include "unicode.h"
  #include "log.h"
  #include "regexp-stack.h"
  #include "macro-assembler.h"
  #include "regexp-macro-assembler.h"
  #include "ia32/regexp-macro-assembler-ia32.h"
  
  namespace v8 {
  namespace internal {
  
  #ifndef V8_INTERPRETED_REGEXP
  /*
   * This assembler uses the following register assignment convention
   * - edx : current character. Must be loaded using LoadCurrentCharacter
   *         before using any of the dispatch methods.
   * - edi : current position in input, as negative offset from end of string.
   *         Please notice that this is the byte offset, not the character offset!
   * - esi : end of input (points to byte after last character in input).
   * - ebp : frame pointer. Used to access arguments, local variables and
   *         RegExp registers.
   * - esp : points to tip of C stack.
   * - ecx : points to tip of backtrack stack
   *
   * The registers eax and ebx are free to use for computations.
   *
   * Each call to a public method should retain this convention.
   * The stack will have the following structure:
   *       - direct_call          (if 1, direct call from JavaScript code, if 0
   *                               call through the runtime system)
   *       - stack_area_base      (High end of the memory area to use as
   *                               backtracking stack)
   *       - int* capture_array   (int[num_saved_registers_], for output).
   *       - end of input         (Address of end of string)
   *       - start of input       (Address of first character in string)
   *       - start index          (character index of start)
   *       - String* input_string (location of a handle containing the string)
   *       --- frame alignment (if applicable) ---
   *       - return address
   * ebp-> - old ebp
   *       - backup of caller esi
   *       - backup of caller edi
   *       - backup of caller ebx
   *       - Offset of location before start of input (effectively character
   *         position -1). Used to initialize capture registers to a non-position.
   *       - register 0  ebp[-4]  (Only positions must be stored in the first
   *       - register 1  ebp[-8]   num_saved_registers_ registers)
   *       - ...
   *
   * The first num_saved_registers_ registers are initialized to point to
   * "character -1" in the string (i.e., char_size() bytes before the first
   * character of the string). The remaining registers starts out as garbage.
   *
   * The data up to the return address must be placed there by the calling
   * code, by calling the code entry as cast to a function with the signature:
   * int (*match)(String* input_string,
   *              int start_index,
   *              Address start,
   *              Address end,
   *              int* capture_output_array,
   *              bool at_start,
   *              byte* stack_area_base,
   *              bool direct_call)
   */
  
  #define __ ACCESS_MASM(masm_)
  
  RegExpMacroAssemblerIA32::RegExpMacroAssemblerIA32(
      Mode mode,
      int registers_to_save)
      : masm_(new MacroAssembler(NULL, kRegExpCodeSize)),
        mode_(mode),
        num_registers_(registers_to_save),
        num_saved_registers_(registers_to_save),
        entry_label_(),
        start_label_(),
        success_label_(),
        backtrack_label_(),
        exit_label_() {
    ASSERT_EQ(0, registers_to_save % 2);
    __ jmp(&entry_label_);   // We'll write the entry code later.
    __ bind(&start_label_);  // And then continue from here.
  }
  
  
  RegExpMacroAssemblerIA32::~RegExpMacroAssemblerIA32() {
    delete masm_;
    // Unuse labels in case we throw away the assembler without calling GetCode.
    entry_label_.Unuse();
    start_label_.Unuse();
    success_label_.Unuse();
    backtrack_label_.Unuse();
    exit_label_.Unuse();
    check_preempt_label_.Unuse();
    stack_overflow_label_.Unuse();
  }
  
  
  int RegExpMacroAssemblerIA32::stack_limit_slack()  {
    return RegExpStack::kStackLimitSlack;
  }
  
  
  void RegExpMacroAssemblerIA32::AdvanceCurrentPosition(int by) {
    if (by != 0) {
      __ add(Operand(edi), Immediate(by * char_size()));
    }
  }
  
  
  void RegExpMacroAssemblerIA32::AdvanceRegister(int reg, int by) {
    ASSERT(reg >= 0);
    ASSERT(reg < num_registers_);
    if (by != 0) {
      __ add(register_location(reg), Immediate(by));
    }
  }
  
  
  void RegExpMacroAssemblerIA32::Backtrack() {
    CheckPreemption();
    // Pop Code* offset from backtrack stack, add Code* and jump to location.
    Pop(ebx);
    __ add(Operand(ebx), Immediate(masm_->CodeObject()));
    __ jmp(Operand(ebx));
  }
  
  
  void RegExpMacroAssemblerIA32::Bind(Label* label) {
    __ bind(label);
  }
  
  
  void RegExpMacroAssemblerIA32::CheckCharacter(uint32_t c, Label* on_equal) {
    __ cmp(current_character(), c);
    BranchOrBacktrack(equal, on_equal);
  }
  
  
  void RegExpMacroAssemblerIA32::CheckCharacterGT(uc16 limit, Label* on_greater) {
    __ cmp(current_character(), limit);
    BranchOrBacktrack(greater, on_greater);
  }
  
  
  void RegExpMacroAssemblerIA32::CheckAtStart(Label* on_at_start) {
    Label not_at_start;
    // Did we start the match at the start of the string at all?
    __ cmp(Operand(ebp, kStartIndex), Immediate(0));
    BranchOrBacktrack(not_equal, &not_at_start);
    // If we did, are we still at the start of the input?
    __ lea(eax, Operand(esi, edi, times_1, 0));
    __ cmp(eax, Operand(ebp, kInputStart));
    BranchOrBacktrack(equal, on_at_start);
    __ bind(&not_at_start);
  }
  
  
  void RegExpMacroAssemblerIA32::CheckNotAtStart(Label* on_not_at_start) {
    // Did we start the match at the start of the string at all?
    __ cmp(Operand(ebp, kStartIndex), Immediate(0));
    BranchOrBacktrack(not_equal, on_not_at_start);
    // If we did, are we still at the start of the input?
    __ lea(eax, Operand(esi, edi, times_1, 0));
    __ cmp(eax, Operand(ebp, kInputStart));
    BranchOrBacktrack(not_equal, on_not_at_start);
  }
  
  
  void RegExpMacroAssemblerIA32::CheckCharacterLT(uc16 limit, Label* on_less) {
    __ cmp(current_character(), limit);
    BranchOrBacktrack(less, on_less);
  }
  
  
  void RegExpMacroAssemblerIA32::CheckCharacters(Vector<const uc16> str,
                                                 int cp_offset,
                                                 Label* on_failure,
                                                 bool check_end_of_string) {
  #ifdef DEBUG
    // If input is ASCII, don't even bother calling here if the string to
    // match contains a non-ascii character.
    if (mode_ == ASCII) {
      for (int i = 0; i < str.length(); i++) {
        ASSERT(str[i] <= String::kMaxAsciiCharCodeU);
      }
    }
  #endif
    int byte_length = str.length() * char_size();
    int byte_offset = cp_offset * char_size();
    if (check_end_of_string) {
      // Check that there are at least str.length() characters left in the input.
      __ cmp(Operand(edi), Immediate(-(byte_offset + byte_length)));
      BranchOrBacktrack(greater, on_failure);
    }
  
    if (on_failure == NULL) {
      // Instead of inlining a backtrack, (re)use the global backtrack target.
      on_failure = &backtrack_label_;
    }
  
    // Do one character test first to minimize loading for the case that
    // we don't match at all (loading more than one character introduces that
    // chance of reading unaligned and reading across cache boundaries).
    // If the first character matches, expect a larger chance of matching the
    // string, and start loading more characters at a time.
    if (mode_ == ASCII) {
      __ cmpb(Operand(esi, edi, times_1, byte_offset),
              static_cast<int8_t>(str[0]));
    } else {
      // Don't use 16-bit immediate. The size changing prefix throws off
      // pre-decoding.
      __ movzx_w(eax,
                 Operand(esi, edi, times_1, byte_offset));
      __ cmp(eax, static_cast<int32_t>(str[0]));
    }
    BranchOrBacktrack(not_equal, on_failure);
  
    __ lea(ebx, Operand(esi, edi, times_1, 0));
    for (int i = 1, n = str.length(); i < n;) {
      if (mode_ == ASCII) {
        if (i <= n - 4) {
          int combined_chars =
              (static_cast<uint32_t>(str[i + 0]) << 0) |
              (static_cast<uint32_t>(str[i + 1]) << 8) |
              (static_cast<uint32_t>(str[i + 2]) << 16) |
              (static_cast<uint32_t>(str[i + 3]) << 24);
          __ cmp(Operand(ebx, byte_offset + i), Immediate(combined_chars));
          i += 4;
        } else {
          __ cmpb(Operand(ebx, byte_offset + i),
                  static_cast<int8_t>(str[i]));
          i += 1;
        }
      } else {
        ASSERT(mode_ == UC16);
        if (i <= n - 2) {
          __ cmp(Operand(ebx, byte_offset + i * sizeof(uc16)),
                 Immediate(*reinterpret_cast<const int*>(&str[i])));
          i += 2;
        } else {
          // Avoid a 16-bit immediate operation. It uses the length-changing
          // 0x66 prefix which causes pre-decoder misprediction and pipeline
          // stalls. See
          // "Intel(R) 64 and IA-32 Architectures Optimization Reference Manual"
          // (248966.pdf) section 3.4.2.3 "Length-Changing Prefixes (LCP)"
          __ movzx_w(eax,
                     Operand(ebx, byte_offset + i * sizeof(uc16)));
          __ cmp(eax, static_cast<int32_t>(str[i]));
          i += 1;
        }
      }
      BranchOrBacktrack(not_equal, on_failure);
    }
  }
  
  
  void RegExpMacroAssemblerIA32::CheckGreedyLoop(Label* on_equal) {
    Label fallthrough;
    __ cmp(edi, Operand(backtrack_stackpointer(), 0));
    __ j(not_equal, &fallthrough);
    __ add(Operand(backtrack_stackpointer()), Immediate(kPointerSize));  // Pop.
    BranchOrBacktrack(no_condition, on_equal);
    __ bind(&fallthrough);
  }
  
  
  void RegExpMacroAssemblerIA32::CheckNotBackReferenceIgnoreCase(
      int start_reg,
      Label* on_no_match) {
    Label fallthrough;
    __ mov(edx, register_location(start_reg));  // Index of start of capture
    __ mov(ebx, register_location(start_reg + 1));  // Index of end of capture
    __ sub(ebx, Operand(edx));  // Length of capture.
  
    // The length of a capture should not be negative. This can only happen
    // if the end of the capture is unrecorded, or at a point earlier than
    // the start of the capture.
    BranchOrBacktrack(less, on_no_match, not_taken);
  
    // If length is zero, either the capture is empty or it is completely
    // uncaptured. In either case succeed immediately.
    __ j(equal, &fallthrough);
  
    if (mode_ == ASCII) {
      Label success;
      Label fail;
      Label loop_increment;
      // Save register contents to make the registers available below.
      __ push(edi);
      __ push(backtrack_stackpointer());
      // After this, the eax, ecx, and edi registers are available.
  
      __ add(edx, Operand(esi));  // Start of capture
      __ add(edi, Operand(esi));  // Start of text to match against capture.
      __ add(ebx, Operand(edi));  // End of text to match against capture.
  
      Label loop;
      __ bind(&loop);
      __ movzx_b(eax, Operand(edi, 0));
      __ cmpb_al(Operand(edx, 0));
      __ j(equal, &loop_increment);
  
      // Mismatch, try case-insensitive match (converting letters to lower-case).
      __ or_(eax, 0x20);  // Convert match character to lower-case.
      __ lea(ecx, Operand(eax, -'a'));
      __ cmp(ecx, static_cast<int32_t>('z' - 'a'));  // Is eax a lowercase letter?
      __ j(above, &fail);
      // Also convert capture character.
      __ movzx_b(ecx, Operand(edx, 0));
      __ or_(ecx, 0x20);
  
      __ cmp(eax, Operand(ecx));
      __ j(not_equal, &fail);
  
      __ bind(&loop_increment);
      // Increment pointers into match and capture strings.
      __ add(Operand(edx), Immediate(1));
      __ add(Operand(edi), Immediate(1));
      // Compare to end of match, and loop if not done.
      __ cmp(edi, Operand(ebx));
      __ j(below, &loop, taken);
      __ jmp(&success);
  
      __ bind(&fail);
      // Restore original values before failing.
      __ pop(backtrack_stackpointer());
      __ pop(edi);
      BranchOrBacktrack(no_condition, on_no_match);
  
      __ bind(&success);
      // Restore original value before continuing.
      __ pop(backtrack_stackpointer());
      // Drop original value of character position.
      __ add(Operand(esp), Immediate(kPointerSize));
      // Compute new value of character position after the matched part.
      __ sub(edi, Operand(esi));
    } else {
      ASSERT(mode_ == UC16);
      // Save registers before calling C function.
      __ push(esi);
      __ push(edi);
      __ push(backtrack_stackpointer());
      __ push(ebx);
  
      static const int argument_count = 3;
      __ PrepareCallCFunction(argument_count, ecx);
      // Put arguments into allocated stack area, last argument highest on stack.
      // Parameters are
      //   Address byte_offset1 - Address captured substring's start.
      //   Address byte_offset2 - Address of current character position.
      //   size_t byte_length - length of capture in bytes(!)
  
      // Set byte_length.
      __ mov(Operand(esp, 2 * kPointerSize), ebx);
      // Set byte_offset2.
      // Found by adding negative string-end offset of current position (edi)
      // to end of string.
      __ add(edi, Operand(esi));
      __ mov(Operand(esp, 1 * kPointerSize), edi);
      // Set byte_offset1.
      // Start of capture, where edx already holds string-end negative offset.
      __ add(edx, Operand(esi));
      __ mov(Operand(esp, 0 * kPointerSize), edx);
  
      ExternalReference compare =
          ExternalReference::re_case_insensitive_compare_uc16();
      __ CallCFunction(compare, argument_count);
      // Pop original values before reacting on result value.
      __ pop(ebx);
      __ pop(backtrack_stackpointer());
      __ pop(edi);
      __ pop(esi);
  
      // Check if function returned non-zero for success or zero for failure.
      __ or_(eax, Operand(eax));
      BranchOrBacktrack(zero, on_no_match);
      // On success, increment position by length of capture.
      __ add(edi, Operand(ebx));
    }
    __ bind(&fallthrough);
  }
  
  
  void RegExpMacroAssemblerIA32::CheckNotBackReference(
      int start_reg,
      Label* on_no_match) {
    Label fallthrough;
    Label success;
    Label fail;
  
    // Find length of back-referenced capture.
    __ mov(edx, register_location(start_reg));
    __ mov(eax, register_location(start_reg + 1));
    __ sub(eax, Operand(edx));  // Length to check.
    // Fail on partial or illegal capture (start of capture after end of capture).
    BranchOrBacktrack(less, on_no_match);
    // Succeed on empty capture (including no capture)
    __ j(equal, &fallthrough);
  
    // Check that there are sufficient characters left in the input.
    __ mov(ebx, edi);
    __ add(ebx, Operand(eax));
    BranchOrBacktrack(greater, on_no_match);
  
    // Save register to make it available below.
    __ push(backtrack_stackpointer());
  
    // Compute pointers to match string and capture string
    __ lea(ebx, Operand(esi, edi, times_1, 0));  // Start of match.
    __ add(edx, Operand(esi));  // Start of capture.
    __ lea(ecx, Operand(eax, ebx, times_1, 0));  // End of match
  
    Label loop;
    __ bind(&loop);
    if (mode_ == ASCII) {
      __ movzx_b(eax, Operand(edx, 0));
      __ cmpb_al(Operand(ebx, 0));
    } else {
      ASSERT(mode_ == UC16);
      __ movzx_w(eax, Operand(edx, 0));
      __ cmpw_ax(Operand(ebx, 0));
    }
    __ j(not_equal, &fail);
    // Increment pointers into capture and match string.
    __ add(Operand(edx), Immediate(char_size()));
    __ add(Operand(ebx), Immediate(char_size()));
    // Check if we have reached end of match area.
    __ cmp(ebx, Operand(ecx));
    __ j(below, &loop);
    __ jmp(&success);
  
    __ bind(&fail);
    // Restore backtrack stackpointer.
    __ pop(backtrack_stackpointer());
    BranchOrBacktrack(no_condition, on_no_match);
  
    __ bind(&success);
    // Move current character position to position after match.
    __ mov(edi, ecx);
    __ sub(Operand(edi), esi);
    // Restore backtrack stackpointer.
    __ pop(backtrack_stackpointer());
  
    __ bind(&fallthrough);
  }
  
  
  void RegExpMacroAssemblerIA32::CheckNotRegistersEqual(int reg1,
                                                        int reg2,
                                                        Label* on_not_equal) {
    __ mov(eax, register_location(reg1));
    __ cmp(eax, register_location(reg2));
    BranchOrBacktrack(not_equal, on_not_equal);
  }
  
  
  void RegExpMacroAssemblerIA32::CheckNotCharacter(uint32_t c,
                                                   Label* on_not_equal) {
    __ cmp(current_character(), c);
    BranchOrBacktrack(not_equal, on_not_equal);
  }
  
  
  void RegExpMacroAssemblerIA32::CheckCharacterAfterAnd(uint32_t c,
                                                        uint32_t mask,
                                                        Label* on_equal) {
    __ mov(eax, current_character());
    __ and_(eax, mask);
    __ cmp(eax, c);
    BranchOrBacktrack(equal, on_equal);
  }
  
  
  void RegExpMacroAssemblerIA32::CheckNotCharacterAfterAnd(uint32_t c,
                                                           uint32_t mask,
                                                           Label* on_not_equal) {
    __ mov(eax, current_character());
    __ and_(eax, mask);
    __ cmp(eax, c);
    BranchOrBacktrack(not_equal, on_not_equal);
  }
  
  
  void RegExpMacroAssemblerIA32::CheckNotCharacterAfterMinusAnd(
      uc16 c,
      uc16 minus,
      uc16 mask,
      Label* on_not_equal) {
    ASSERT(minus < String::kMaxUC16CharCode);
    __ lea(eax, Operand(current_character(), -minus));
    __ and_(eax, mask);
    __ cmp(eax, c);
    BranchOrBacktrack(not_equal, on_not_equal);
  }
  
  
  bool RegExpMacroAssemblerIA32::CheckSpecialCharacterClass(uc16 type,
                                                            Label* on_no_match) {
    // Range checks (c in min..max) are generally implemented by an unsigned
    // (c - min) <= (max - min) check
    switch (type) {
    case 's':
      // Match space-characters
      if (mode_ == ASCII) {
        // ASCII space characters are '\t'..'\r' and ' '.
        Label success;
        __ cmp(current_character(), ' ');
        __ j(equal, &success);
        // Check range 0x09..0x0d
        __ lea(eax, Operand(current_character(), -'\t'));
        __ cmp(eax, '\r' - '\t');
        BranchOrBacktrack(above, on_no_match);
        __ bind(&success);
        return true;
      }
      return false;
    case 'S':
      // Match non-space characters.
      if (mode_ == ASCII) {
        // ASCII space characters are '\t'..'\r' and ' '.
        __ cmp(current_character(), ' ');
        BranchOrBacktrack(equal, on_no_match);
        __ lea(eax, Operand(current_character(), -'\t'));
        __ cmp(eax, '\r' - '\t');
        BranchOrBacktrack(below_equal, on_no_match);
        return true;
      }
      return false;
    case 'd':
      // Match ASCII digits ('0'..'9')
      __ lea(eax, Operand(current_character(), -'0'));
      __ cmp(eax, '9' - '0');
      BranchOrBacktrack(above, on_no_match);
      return true;
    case 'D':
      // Match non ASCII-digits
      __ lea(eax, Operand(current_character(), -'0'));
      __ cmp(eax, '9' - '0');
      BranchOrBacktrack(below_equal, on_no_match);
      return true;
    case '.': {
      // Match non-newlines (not 0x0a('\n'), 0x0d('\r'), 0x2028 and 0x2029)
      __ mov(Operand(eax), current_character());
      __ xor_(Operand(eax), Immediate(0x01));
      // See if current character is '\n'^1 or '\r'^1, i.e., 0x0b or 0x0c
      __ sub(Operand(eax), Immediate(0x0b));
      __ cmp(eax, 0x0c - 0x0b);
      BranchOrBacktrack(below_equal, on_no_match);
      if (mode_ == UC16) {
        // Compare original value to 0x2028 and 0x2029, using the already
        // computed (current_char ^ 0x01 - 0x0b). I.e., check for
        // 0x201d (0x2028 - 0x0b) or 0x201e.
        __ sub(Operand(eax), Immediate(0x2028 - 0x0b));
        __ cmp(eax, 0x2029 - 0x2028);
        BranchOrBacktrack(below_equal, on_no_match);
      }
      return true;
    }
    case 'w': {
      if (mode_ != ASCII) {
        // Table is 128 entries, so all ASCII characters can be tested.
        __ cmp(Operand(current_character()), Immediate('z'));
        BranchOrBacktrack(above, on_no_match);
      }
      ASSERT_EQ(0, word_character_map[0]);  // Character '\0' is not a word char.
      ExternalReference word_map = ExternalReference::re_word_character_map();
      __ test_b(current_character(),
                Operand::StaticArray(current_character(), times_1, word_map));
      BranchOrBacktrack(zero, on_no_match);
      return true;
    }
    case 'W': {
      Label done;
      if (mode_ != ASCII) {
        // Table is 128 entries, so all ASCII characters can be tested.
        __ cmp(Operand(current_character()), Immediate('z'));
        __ j(above, &done);
      }
      ASSERT_EQ(0, word_character_map[0]);  // Character '\0' is not a word char.
      ExternalReference word_map = ExternalReference::re_word_character_map();
      __ test_b(current_character(),
                Operand::StaticArray(current_character(), times_1, word_map));
      BranchOrBacktrack(not_zero, on_no_match);
      if (mode_ != ASCII) {
        __ bind(&done);
      }
      return true;
    }
    // Non-standard classes (with no syntactic shorthand) used internally.
    case '*':
      // Match any character.
      return true;
    case 'n': {
      // Match newlines (0x0a('\n'), 0x0d('\r'), 0x2028 or 0x2029).
      // The opposite of '.'.
      __ mov(Operand(eax), current_character());
      __ xor_(Operand(eax), Immediate(0x01));
      // See if current character is '\n'^1 or '\r'^1, i.e., 0x0b or 0x0c
      __ sub(Operand(eax), Immediate(0x0b));
      __ cmp(eax, 0x0c - 0x0b);
      if (mode_ == ASCII) {
        BranchOrBacktrack(above, on_no_match);
      } else {
        Label done;
        BranchOrBacktrack(below_equal, &done);
        ASSERT_EQ(UC16, mode_);
        // Compare original value to 0x2028 and 0x2029, using the already
        // computed (current_char ^ 0x01 - 0x0b). I.e., check for
        // 0x201d (0x2028 - 0x0b) or 0x201e.
        __ sub(Operand(eax), Immediate(0x2028 - 0x0b));
        __ cmp(eax, 1);
        BranchOrBacktrack(above, on_no_match);
        __ bind(&done);
      }
      return true;
    }
    // No custom implementation (yet): s(UC16), S(UC16).
    default:
      return false;
    }
  }
  
  
  void RegExpMacroAssemblerIA32::Fail() {
    ASSERT(FAILURE == 0);  // Return value for failure is zero.
    __ xor_(eax, Operand(eax));  // zero eax.
    __ jmp(&exit_label_);
  }
  
  
  Handle<Object> RegExpMacroAssemblerIA32::GetCode(Handle<String> source) {
    // Finalize code - write the entry point code now we know how many
    // registers we need.
  
    // Entry code:
    __ bind(&entry_label_);
    // Start new stack frame.
    __ push(ebp);
    __ mov(ebp, esp);
    // Save callee-save registers. Order here should correspond to order of
    // kBackup_ebx etc.
    __ push(esi);
    __ push(edi);
    __ push(ebx);  // Callee-save on MacOS.
    __ push(Immediate(0));  // Make room for "input start - 1" constant.
  
    // Check if we have space on the stack for registers.
    Label stack_limit_hit;
    Label stack_ok;
  
    ExternalReference stack_limit =
        ExternalReference::address_of_stack_limit();
    __ mov(ecx, esp);
    __ sub(ecx, Operand::StaticVariable(stack_limit));
    // Handle it if the stack pointer is already below the stack limit.
    __ j(below_equal, &stack_limit_hit, not_taken);
    // Check if there is room for the variable number of registers above
    // the stack limit.
    __ cmp(ecx, num_registers_ * kPointerSize);
    __ j(above_equal, &stack_ok, taken);
    // Exit with OutOfMemory exception. There is not enough space on the stack
    // for our working registers.
    __ mov(eax, EXCEPTION);
    __ jmp(&exit_label_);
  
    __ bind(&stack_limit_hit);
    CallCheckStackGuardState(ebx);
    __ or_(eax, Operand(eax));
    // If returned value is non-zero, we exit with the returned value as result.
    __ j(not_zero, &exit_label_);
  
    __ bind(&stack_ok);
    // Load start index for later use.
    __ mov(ebx, Operand(ebp, kStartIndex));
  
    // Allocate space on stack for registers.
    __ sub(Operand(esp), Immediate(num_registers_ * kPointerSize));
    // Load string length.
    __ mov(esi, Operand(ebp, kInputEnd));
    // Load input position.
    __ mov(edi, Operand(ebp, kInputStart));
    // Set up edi to be negative offset from string end.
    __ sub(edi, Operand(esi));
  
    // Set eax to address of char before start of the string.
    // (effectively string position -1).
    __ neg(ebx);
    if (mode_ == UC16) {
      __ lea(eax, Operand(edi, ebx, times_2, -char_size()));
    } else {
      __ lea(eax, Operand(edi, ebx, times_1, -char_size()));
    }
    // Store this value in a local variable, for use when clearing
    // position registers.
    __ mov(Operand(ebp, kInputStartMinusOne), eax);
  
    if (num_saved_registers_ > 0) {  // Always is, if generated from a regexp.
      // Fill saved registers with initial value = start offset - 1
      // Fill in stack push order, to avoid accessing across an unwritten
      // page (a problem on Windows).
      __ mov(ecx, kRegisterZero);
      Label init_loop;
      __ bind(&init_loop);
      __ mov(Operand(ebp, ecx, times_1, +0), eax);
      __ sub(Operand(ecx), Immediate(kPointerSize));
      __ cmp(ecx, kRegisterZero - num_saved_registers_ * kPointerSize);
      __ j(greater, &init_loop);
    }
    // Ensure that we have written to each stack page, in order. Skipping a page
    // on Windows can cause segmentation faults. Assuming page size is 4k.
    const int kPageSize = 4096;
    const int kRegistersPerPage = kPageSize / kPointerSize;
    for (int i = num_saved_registers_ + kRegistersPerPage - 1;
        i < num_registers_;
        i += kRegistersPerPage) {
      __ mov(register_location(i), eax);  // One write every page.
    }
  
  
    // Initialize backtrack stack pointer.
    __ mov(backtrack_stackpointer(), Operand(ebp, kStackHighEnd));
    // Load previous char as initial value of current-character.
    Label at_start;
    __ cmp(Operand(ebp, kStartIndex), Immediate(0));
    __ j(equal, &at_start);
    LoadCurrentCharacterUnchecked(-1, 1);  // Load previous char.
    __ jmp(&start_label_);
    __ bind(&at_start);
    __ mov(current_character(), '\n');
    __ jmp(&start_label_);
  
  
    // Exit code:
    if (success_label_.is_linked()) {
      // Save captures when successful.
      __ bind(&success_label_);
      if (num_saved_registers_ > 0) {
        // copy captures to output
        __ mov(ebx, Operand(ebp, kRegisterOutput));
        __ mov(ecx, Operand(ebp, kInputEnd));
        __ mov(edx, Operand(ebp, kStartIndex));
        __ sub(ecx, Operand(ebp, kInputStart));
        if (mode_ == UC16) {
          __ lea(ecx, Operand(ecx, edx, times_2, 0));
        } else {
          __ add(ecx, Operand(edx));
        }
        for (int i = 0; i < num_saved_registers_; i++) {
          __ mov(eax, register_location(i));
          // Convert to index from start of string, not end.
          __ add(eax, Operand(ecx));
          if (mode_ == UC16) {
            __ sar(eax, 1);  // Convert byte index to character index.
          }
          __ mov(Operand(ebx, i * kPointerSize), eax);
        }
      }
      __ mov(eax, Immediate(SUCCESS));
    }
    // Exit and return eax
    __ bind(&exit_label_);
    // Skip esp past regexp registers.
    __ lea(esp, Operand(ebp, kBackup_ebx));
    // Restore callee-save registers.
    __ pop(ebx);
    __ pop(edi);
    __ pop(esi);
    // Exit function frame, restore previous one.
    __ pop(ebp);
    __ ret(0);
  
    // Backtrack code (branch target for conditional backtracks).
    if (backtrack_label_.is_linked()) {
      __ bind(&backtrack_label_);
      Backtrack();
    }
  
    Label exit_with_exception;
  
    // Preempt-code
    if (check_preempt_label_.is_linked()) {
      SafeCallTarget(&check_preempt_label_);
  
      __ push(backtrack_stackpointer());
      __ push(edi);
  
      CallCheckStackGuardState(ebx);
      __ or_(eax, Operand(eax));
      // If returning non-zero, we should end execution with the given
      // result as return value.
      __ j(not_zero, &exit_label_);
  
      __ pop(edi);
      __ pop(backtrack_stackpointer());
      // String might have moved: Reload esi from frame.
      __ mov(esi, Operand(ebp, kInputEnd));
      SafeReturn();
    }
  
    // Backtrack stack overflow code.
    if (stack_overflow_label_.is_linked()) {
      SafeCallTarget(&stack_overflow_label_);
      // Reached if the backtrack-stack limit has been hit.
  
      Label grow_failed;
      // Save registers before calling C function
      __ push(esi);
      __ push(edi);
  
      // Call GrowStack(backtrack_stackpointer())
      static const int num_arguments = 2;
      __ PrepareCallCFunction(num_arguments, ebx);
      __ lea(eax, Operand(ebp, kStackHighEnd));
      __ mov(Operand(esp, 1 * kPointerSize), eax);
      __ mov(Operand(esp, 0 * kPointerSize), backtrack_stackpointer());
      ExternalReference grow_stack = ExternalReference::re_grow_stack();
      __ CallCFunction(grow_stack, num_arguments);
      // If return NULL, we have failed to grow the stack, and
      // must exit with a stack-overflow exception.
      __ or_(eax, Operand(eax));
      __ j(equal, &exit_with_exception);
      // Otherwise use return value as new stack pointer.
      __ mov(backtrack_stackpointer(), eax);
      // Restore saved registers and continue.
      __ pop(edi);
      __ pop(esi);
      SafeReturn();
    }
  
    if (exit_with_exception.is_linked()) {
      // If any of the code above needed to exit with an exception.
      __ bind(&exit_with_exception);
      // Exit with Result EXCEPTION(-1) to signal thrown exception.
      __ mov(eax, EXCEPTION);
      __ jmp(&exit_label_);
    }
  
    CodeDesc code_desc;
    masm_->GetCode(&code_desc);
    Handle<Code> code = Factory::NewCode(code_desc,
                                         Code::ComputeFlags(Code::REGEXP),
                                         masm_->CodeObject());
    PROFILE(RegExpCodeCreateEvent(*code, *source));
    return Handle<Object>::cast(code);
  }
  
  
  void RegExpMacroAssemblerIA32::GoTo(Label* to) {
    BranchOrBacktrack(no_condition, to);
  }
  
  
  void RegExpMacroAssemblerIA32::IfRegisterGE(int reg,
                                              int comparand,
                                              Label* if_ge) {
    __ cmp(register_location(reg), Immediate(comparand));
    BranchOrBacktrack(greater_equal, if_ge);
  }
  
  
  void RegExpMacroAssemblerIA32::IfRegisterLT(int reg,
                                              int comparand,
                                              Label* if_lt) {
    __ cmp(register_location(reg), Immediate(comparand));
    BranchOrBacktrack(less, if_lt);
  }
  
  
  void RegExpMacroAssemblerIA32::IfRegisterEqPos(int reg,
                                                 Label* if_eq) {
    __ cmp(edi, register_location(reg));
    BranchOrBacktrack(equal, if_eq);
  }
  
  
  RegExpMacroAssembler::IrregexpImplementation
      RegExpMacroAssemblerIA32::Implementation() {
    return kIA32Implementation;
  }
  
  
  void RegExpMacroAssemblerIA32::LoadCurrentCharacter(int cp_offset,
                                                      Label* on_end_of_input,
                                                      bool check_bounds,
                                                      int characters) {
    ASSERT(cp_offset >= -1);      // ^ and \b can look behind one character.
    ASSERT(cp_offset < (1<<30));  // Be sane! (And ensure negation works)
    if (check_bounds) {
      CheckPosition(cp_offset + characters - 1, on_end_of_input);
    }
    LoadCurrentCharacterUnchecked(cp_offset, characters);
  }
  
  
  void RegExpMacroAssemblerIA32::PopCurrentPosition() {
    Pop(edi);
  }
  
  
  void RegExpMacroAssemblerIA32::PopRegister(int register_index) {
    Pop(eax);
    __ mov(register_location(register_index), eax);
  }
  
  
  void RegExpMacroAssemblerIA32::PushBacktrack(Label* label) {
    Push(Immediate::CodeRelativeOffset(label));
    CheckStackLimit();
  }
  
  
  void RegExpMacroAssemblerIA32::PushCurrentPosition() {
    Push(edi);
  }
  
  
  void RegExpMacroAssemblerIA32::PushRegister(int register_index,
                                              StackCheckFlag check_stack_limit) {
    __ mov(eax, register_location(register_index));
    Push(eax);
    if (check_stack_limit) CheckStackLimit();
  }
  
  
  void RegExpMacroAssemblerIA32::ReadCurrentPositionFromRegister(int reg) {
    __ mov(edi, register_location(reg));
  }
  
  
  void RegExpMacroAssemblerIA32::ReadStackPointerFromRegister(int reg) {
    __ mov(backtrack_stackpointer(), register_location(reg));
    __ add(backtrack_stackpointer(), Operand(ebp, kStackHighEnd));
  }
  
  void RegExpMacroAssemblerIA32::SetCurrentPositionFromEnd(int by)  {
    NearLabel after_position;
    __ cmp(edi, -by * char_size());
    __ j(greater_equal, &after_position);
    __ mov(edi, -by * char_size());
    // On RegExp code entry (where this operation is used), the character before
    // the current position is expected to be already loaded.
    // We have advanced the position, so it's safe to read backwards.
    LoadCurrentCharacterUnchecked(-1, 1);
    __ bind(&after_position);
  }
  
  void RegExpMacroAssemblerIA32::SetRegister(int register_index, int to) {
    ASSERT(register_index >= num_saved_registers_);  // Reserved for positions!
    __ mov(register_location(register_index), Immediate(to));
  }
  
  
  void RegExpMacroAssemblerIA32::Succeed() {
    __ jmp(&success_label_);
  }
  
  
  void RegExpMacroAssemblerIA32::WriteCurrentPositionToRegister(int reg,
                                                                int cp_offset) {
    if (cp_offset == 0) {
      __ mov(register_location(reg), edi);
    } else {
      __ lea(eax, Operand(edi, cp_offset * char_size()));
      __ mov(register_location(reg), eax);
    }
  }
  
  
  void RegExpMacroAssemblerIA32::ClearRegisters(int reg_from, int reg_to) {
    ASSERT(reg_from <= reg_to);
    __ mov(eax, Operand(ebp, kInputStartMinusOne));
    for (int reg = reg_from; reg <= reg_to; reg++) {
      __ mov(register_location(reg), eax);
    }
  }
  
  
  void RegExpMacroAssemblerIA32::WriteStackPointerToRegister(int reg) {
    __ mov(eax, backtrack_stackpointer());
    __ sub(eax, Operand(ebp, kStackHighEnd));
    __ mov(register_location(reg), eax);
  }
  
  
  // Private methods:
  
  void RegExpMacroAssemblerIA32::CallCheckStackGuardState(Register scratch) {
    static const int num_arguments = 3;
    __ PrepareCallCFunction(num_arguments, scratch);
    // RegExp code frame pointer.
    __ mov(Operand(esp, 2 * kPointerSize), ebp);
    // Code* of self.
    __ mov(Operand(esp, 1 * kPointerSize), Immediate(masm_->CodeObject()));
    // Next address on the stack (will be address of return address).
    __ lea(eax, Operand(esp, -kPointerSize));
    __ mov(Operand(esp, 0 * kPointerSize), eax);
    ExternalReference check_stack_guard =
        ExternalReference::re_check_stack_guard_state();
    __ CallCFunction(check_stack_guard, num_arguments);
  }
  
  
  // Helper function for reading a value out of a stack frame.
  template <typename T>
  static T& frame_entry(Address re_frame, int frame_offset) {
    return reinterpret_cast<T&>(Memory::int32_at(re_frame + frame_offset));
  }
  
  
  int RegExpMacroAssemblerIA32::CheckStackGuardState(Address* return_address,
                                                     Code* re_code,
                                                     Address re_frame) {
    if (StackGuard::IsStackOverflow()) {
      Top::StackOverflow();
      return EXCEPTION;
    }
  
    // If not real stack overflow the stack guard was used to interrupt
    // execution for another purpose.
  
    // If this is a direct call from JavaScript retry the RegExp forcing the call
    // through the runtime system. Currently the direct call cannot handle a GC.
    if (frame_entry<int>(re_frame, kDirectCall) == 1) {
      return RETRY;
    }
  
    // Prepare for possible GC.
    HandleScope handles;
    Handle<Code> code_handle(re_code);
  
    Handle<String> subject(frame_entry<String*>(re_frame, kInputString));
    // Current string.
    bool is_ascii = subject->IsAsciiRepresentation();
  
    ASSERT(re_code->instruction_start() <= *return_address);
    ASSERT(*return_address <=
        re_code->instruction_start() + re_code->instruction_size());
  
    MaybeObject* result = Execution::HandleStackGuardInterrupt();
  
    if (*code_handle != re_code) {  // Return address no longer valid
      int delta = *code_handle - re_code;
      // Overwrite the return address on the stack.
      *return_address += delta;
    }
  
    if (result->IsException()) {
      return EXCEPTION;
    }
  
    // String might have changed.
    if (subject->IsAsciiRepresentation() != is_ascii) {
      // If we changed between an ASCII and an UC16 string, the specialized
      // code cannot be used, and we need to restart regexp matching from
      // scratch (including, potentially, compiling a new version of the code).
      return RETRY;
    }
  
    // Otherwise, the content of the string might have moved. It must still
    // be a sequential or external string with the same content.
    // Update the start and end pointers in the stack frame to the current
    // location (whether it has actually moved or not).
    ASSERT(StringShape(*subject).IsSequential() ||
        StringShape(*subject).IsExternal());
  
    // The original start address of the characters to match.
    const byte* start_address = frame_entry<const byte*>(re_frame, kInputStart);
  
    // Find the current start address of the same character at the current string
    // position.
    int start_index = frame_entry<int>(re_frame, kStartIndex);
    const byte* new_address = StringCharacterPosition(*subject, start_index);
  
    if (start_address != new_address) {
      // If there is a difference, update the object pointer and start and end
      // addresses in the RegExp stack frame to match the new value.
      const byte* end_address = frame_entry<const byte* >(re_frame, kInputEnd);
      int byte_length = end_address - start_address;
      frame_entry<const String*>(re_frame, kInputString) = *subject;
      frame_entry<const byte*>(re_frame, kInputStart) = new_address;
      frame_entry<const byte*>(re_frame, kInputEnd) = new_address + byte_length;
    }
  
    return 0;
  }
  
  
  Operand RegExpMacroAssemblerIA32::register_location(int register_index) {
    ASSERT(register_index < (1<<30));
    if (num_registers_ <= register_index) {
      num_registers_ = register_index + 1;
    }
    return Operand(ebp, kRegisterZero - register_index * kPointerSize);
  }
  
  
  void RegExpMacroAssemblerIA32::CheckPosition(int cp_offset,
                                               Label* on_outside_input) {
    __ cmp(edi, -cp_offset * char_size());
    BranchOrBacktrack(greater_equal, on_outside_input);
  }
  
  
  void RegExpMacroAssemblerIA32::BranchOrBacktrack(Condition condition,
                                                   Label* to,
                                                   Hint hint) {
    if (condition < 0) {  // No condition
      if (to == NULL) {
        Backtrack();
        return;
      }
      __ jmp(to);
      return;
    }
    if (to == NULL) {
      __ j(condition, &backtrack_label_, hint);
      return;
    }
    __ j(condition, to, hint);
  }
  
  
  void RegExpMacroAssemblerIA32::SafeCall(Label* to) {
    Label return_to;
    __ push(Immediate::CodeRelativeOffset(&return_to));
    __ jmp(to);
    __ bind(&return_to);
  }
  
  
  void RegExpMacroAssemblerIA32::SafeReturn() {
    __ pop(ebx);
    __ add(Operand(ebx), Immediate(masm_->CodeObject()));
    __ jmp(Operand(ebx));
  }
  
  
  void RegExpMacroAssemblerIA32::SafeCallTarget(Label* name) {
    __ bind(name);
  }
  
  
  void RegExpMacroAssemblerIA32::Push(Register source) {
    ASSERT(!source.is(backtrack_stackpointer()));
    // Notice: This updates flags, unlike normal Push.
    __ sub(Operand(backtrack_stackpointer()), Immediate(kPointerSize));
    __ mov(Operand(backtrack_stackpointer(), 0), source);
  }
  
  
  void RegExpMacroAssemblerIA32::Push(Immediate value) {
    // Notice: This updates flags, unlike normal Push.
    __ sub(Operand(backtrack_stackpointer()), Immediate(kPointerSize));
    __ mov(Operand(backtrack_stackpointer(), 0), value);
  }
  
  
  void RegExpMacroAssemblerIA32::Pop(Register target) {
    ASSERT(!target.is(backtrack_stackpointer()));
    __ mov(target, Operand(backtrack_stackpointer(), 0));
    // Notice: This updates flags, unlike normal Pop.
    __ add(Operand(backtrack_stackpointer()), Immediate(kPointerSize));
  }
  
  
  void RegExpMacroAssemblerIA32::CheckPreemption() {
    // Check for preemption.
    Label no_preempt;
    ExternalReference stack_limit =
        ExternalReference::address_of_stack_limit();
    __ cmp(esp, Operand::StaticVariable(stack_limit));
    __ j(above, &no_preempt, taken);
  
    SafeCall(&check_preempt_label_);
  
    __ bind(&no_preempt);
  }
  
  
  void RegExpMacroAssemblerIA32::CheckStackLimit() {
    Label no_stack_overflow;
    ExternalReference stack_limit =
        ExternalReference::address_of_regexp_stack_limit();
    __ cmp(backtrack_stackpointer(), Operand::StaticVariable(stack_limit));
    __ j(above, &no_stack_overflow);
  
    SafeCall(&stack_overflow_label_);
  
    __ bind(&no_stack_overflow);
  }
  
  
  void RegExpMacroAssemblerIA32::LoadCurrentCharacterUnchecked(int cp_offset,
                                                               int characters) {
    if (mode_ == ASCII) {
      if (characters == 4) {
        __ mov(current_character(), Operand(esi, edi, times_1, cp_offset));
      } else if (characters == 2) {
        __ movzx_w(current_character(), Operand(esi, edi, times_1, cp_offset));
      } else {
        ASSERT(characters == 1);
        __ movzx_b(current_character(), Operand(esi, edi, times_1, cp_offset));
      }
    } else {
      ASSERT(mode_ == UC16);
      if (characters == 2) {
        __ mov(current_character(),
               Operand(esi, edi, times_1, cp_offset * sizeof(uc16)));
      } else {
        ASSERT(characters == 1);
        __ movzx_w(current_character(),
                   Operand(esi, edi, times_1, cp_offset * sizeof(uc16)));
      }
    }
  }
  
  
  #undef __
  
  #endif  // V8_INTERPRETED_REGEXP
  
  }}  // namespace v8::internal
  
  #endif  // V8_TARGET_ARCH_IA32
  