src/ia32/regexp-macro-assembler-ia32.cc

root/src/ia32/regexp-macro-assembler-ia32.cc

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DEFINITIONS

This source file includes following definitions.
exit_label_
stack_limit_slack
AdvanceCurrentPosition
AdvanceRegister
Backtrack
Bind
CheckCharacter
CheckCharacterGT
CheckAtStart
CheckNotAtStart
CheckCharacterLT
CheckCharacters
CheckGreedyLoop
CheckNotBackReferenceIgnoreCase
CheckNotBackReference
CheckNotCharacter
CheckCharacterAfterAnd
CheckNotCharacterAfterAnd
CheckNotCharacterAfterMinusAnd
CheckCharacterInRange
CheckCharacterNotInRange
CheckBitInTable
CheckSpecialCharacterClass
Fail
GetCode
GoTo
IfRegisterGE
IfRegisterLT
IfRegisterEqPos
Implementation
LoadCurrentCharacter
PopCurrentPosition
PopRegister
PushBacktrack
PushCurrentPosition
PushRegister
ReadCurrentPositionFromRegister
ReadStackPointerFromRegister
SetCurrentPositionFromEnd
SetRegister
Succeed
WriteCurrentPositionToRegister
ClearRegisters
WriteStackPointerToRegister
CallCheckStackGuardState
frame_entry
CheckStackGuardState
register_location
CheckPosition
BranchOrBacktrack
SafeCall
SafeReturn
SafeCallTarget
Push
Push
Pop
CheckPreemption
CheckStackLimit
LoadCurrentCharacterUnchecked
// Copyright 2012 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.  Temporarily stores the
 *         index of capture start after a matching pass for a global regexp.
 * - 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:
 *       - Isolate* isolate     (address of the current isolate)
 *       - 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)
 *       - capture array size   (may fit multiple sets of matches)
 *       - 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
 *       - success counter      (only for global regexps to count matches).
 *       - 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,
    Zone* zone)
    : NativeRegExpMacroAssembler(zone),
      masm_(new MacroAssembler(Isolate::Current(), 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(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(ebx, Immediate(masm_->CodeObject()));
  __ jmp(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) {
    ASSERT(String::IsAscii(str.start(), str.length()));
  }
#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(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(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, 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);

  // If length is zero, either the capture is empty or it is completely
  // uncaptured. In either case succeed immediately.
  __ j(equal, &fallthrough);

  // Check that there are sufficient characters left in the input.
  __ mov(eax, edi);
  __ add(eax, ebx);
  BranchOrBacktrack(greater, on_no_match);

  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, esi);  // Start of capture
    __ add(edi, esi);  // Start of text to match against capture.
    __ add(ebx, 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, ecx);
    __ j(not_equal, &fail);

    __ bind(&loop_increment);
    // Increment pointers into match and capture strings.
    __ add(edx, Immediate(1));
    __ add(edi, Immediate(1));
    // Compare to end of match, and loop if not done.
    __ cmp(edi, ebx);
    __ j(below, &loop);
    __ 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(esp, Immediate(kPointerSize));
    // Compute new value of character position after the matched part.
    __ sub(edi, 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 = 4;
    __ 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(!)
    //   Isolate* isolate

    // Set isolate.
    __ mov(Operand(esp, 3 * kPointerSize),
           Immediate(ExternalReference::isolate_address()));
    // 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, esi);
    __ mov(Operand(esp, 1 * kPointerSize), edi);
    // Set byte_offset1.
    // Start of capture, where edx already holds string-end negative offset.
    __ add(edx, esi);
    __ mov(Operand(esp, 0 * kPointerSize), edx);

    {
      AllowExternalCallThatCantCauseGC scope(masm_);
      ExternalReference compare =
          ExternalReference::re_case_insensitive_compare_uc16(masm_->isolate());
      __ 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, eax);
    BranchOrBacktrack(zero, on_no_match);
    // On success, increment position by length of capture.
    __ add(edi, 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, 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, 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, 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(edx, Immediate(char_size()));
  __ add(ebx, Immediate(char_size()));
  // Check if we have reached end of match area.
  __ cmp(ebx, 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(edi, esi);
  // Restore backtrack stackpointer.
  __ pop(backtrack_stackpointer());

  __ bind(&fallthrough);
}


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) {
  if (c == 0) {
    __ test(current_character(), Immediate(mask));
  } else {
    __ mov(eax, mask);
    __ and_(eax, current_character());
    __ cmp(eax, c);
  }
  BranchOrBacktrack(equal, on_equal);
}


void RegExpMacroAssemblerIA32::CheckNotCharacterAfterAnd(uint32_t c,
                                                         uint32_t mask,
                                                         Label* on_not_equal) {
  if (c == 0) {
    __ test(current_character(), Immediate(mask));
  } else {
    __ mov(eax, mask);
    __ and_(eax, current_character());
    __ 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::kMaxUtf16CodeUnit);
  __ lea(eax, Operand(current_character(), -minus));
  if (c == 0) {
    __ test(eax, Immediate(mask));
  } else {
    __ and_(eax, mask);
    __ cmp(eax, c);
  }
  BranchOrBacktrack(not_equal, on_not_equal);
}


void RegExpMacroAssemblerIA32::CheckCharacterInRange(
    uc16 from,
    uc16 to,
    Label* on_in_range) {
  __ lea(eax, Operand(current_character(), -from));
  __ cmp(eax, to - from);
  BranchOrBacktrack(below_equal, on_in_range);
}


void RegExpMacroAssemblerIA32::CheckCharacterNotInRange(
    uc16 from,
    uc16 to,
    Label* on_not_in_range) {
  __ lea(eax, Operand(current_character(), -from));
  __ cmp(eax, to - from);
  BranchOrBacktrack(above, on_not_in_range);
}


void RegExpMacroAssemblerIA32::CheckBitInTable(
    Handle<ByteArray> table,
    Label* on_bit_set) {
  __ mov(eax, Immediate(table));
  Register index = current_character();
  if (mode_ != ASCII || kTableMask != String::kMaxAsciiCharCode) {
    __ mov(ebx, kTableSize - 1);
    __ and_(ebx, current_character());
    index = ebx;
  }
  __ cmpb(FieldOperand(eax, index, times_1, ByteArray::kHeaderSize), 0);
  BranchOrBacktrack(not_equal, on_bit_set);
}


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(eax, current_character());
    __ xor_(eax, Immediate(0x01));
    // See if current character is '\n'^1 or '\r'^1, i.e., 0x0b or 0x0c
    __ sub(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(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(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(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(eax, current_character());
    __ xor_(eax, Immediate(0x01));
    // See if current character is '\n'^1 or '\r'^1, i.e., 0x0b or 0x0c
    __ sub(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(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() {
  STATIC_ASSERT(FAILURE == 0);  // Return value for failure is zero.
  if (!global()) {
    __ Set(eax, Immediate(FAILURE));
  }
  __ jmp(&exit_label_);
}


Handle<HeapObject> RegExpMacroAssemblerIA32::GetCode(Handle<String> source) {
  Label return_eax;
  // Finalize code - write the entry point code now we know how many
  // registers we need.

  // Entry code:
  __ bind(&entry_label_);

  // Tell the system that we have a stack frame.  Because the type is MANUAL, no
  // code is generated.
  FrameScope scope(masm_, StackFrame::MANUAL);

  // Actually emit code to start a 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));  // Number of successful matches in a global regexp.
  __ 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(masm_->isolate());
  __ 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);
  // 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);
  // Exit with OutOfMemory exception. There is not enough space on the stack
  // for our working registers.
  __ mov(eax, EXCEPTION);
  __ jmp(&return_eax);

  __ bind(&stack_limit_hit);
  CallCheckStackGuardState(ebx);
  __ or_(eax, eax);
  // If returned value is non-zero, we exit with the returned value as result.
  __ j(not_zero, &return_eax);

  __ bind(&stack_ok);
  // Load start index for later use.
  __ mov(ebx, Operand(ebp, kStartIndex));

  // Allocate space on stack for registers.
  __ sub(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, 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);

#ifdef WIN32
  // Ensure that we write 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.
  }
#endif  // WIN32

  Label load_char_start_regexp, start_regexp;
  // Load newline if index is at start, previous character otherwise.
  __ cmp(Operand(ebp, kStartIndex), Immediate(0));
  __ j(not_equal, &load_char_start_regexp, Label::kNear);
  __ mov(current_character(), '\n');
  __ jmp(&start_regexp, Label::kNear);

  // Global regexp restarts matching here.
  __ bind(&load_char_start_regexp);
  // Load previous char as initial value of current character register.
  LoadCurrentCharacterUnchecked(-1, 1);
  __ bind(&start_regexp);

  // Initialize on-stack registers.
  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).
    if (num_saved_registers_ > 8) {
      __ mov(ecx, kRegisterZero);
      Label init_loop;
      __ bind(&init_loop);
      __ mov(Operand(ebp, ecx, times_1, 0), eax);
      __ sub(ecx, Immediate(kPointerSize));
      __ cmp(ecx, kRegisterZero - num_saved_registers_ * kPointerSize);
      __ j(greater, &init_loop);
    } else {  // Unroll the loop.
      for (int i = 0; i < num_saved_registers_; i++) {
        __ mov(register_location(i), eax);
      }
    }
  }

  // Initialize backtrack stack pointer.
  __ mov(backtrack_stackpointer(), Operand(ebp, kStackHighEnd));

  __ 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, edx);
      }
      for (int i = 0; i < num_saved_registers_; i++) {
        __ mov(eax, register_location(i));
        if (i == 0 && global_with_zero_length_check()) {
          // Keep capture start in edx for the zero-length check later.
          __ mov(edx, eax);
        }
        // Convert to index from start of string, not end.
        __ add(eax, ecx);
        if (mode_ == UC16) {
          __ sar(eax, 1);  // Convert byte index to character index.
        }
        __ mov(Operand(ebx, i * kPointerSize), eax);
      }
    }

    if (global()) {
    // Restart matching if the regular expression is flagged as global.
      // Increment success counter.
      __ inc(Operand(ebp, kSuccessfulCaptures));
      // Capture results have been stored, so the number of remaining global
      // output registers is reduced by the number of stored captures.
      __ mov(ecx, Operand(ebp, kNumOutputRegisters));
      __ sub(ecx, Immediate(num_saved_registers_));
      // Check whether we have enough room for another set of capture results.
      __ cmp(ecx, Immediate(num_saved_registers_));
      __ j(less, &exit_label_);

      __ mov(Operand(ebp, kNumOutputRegisters), ecx);
      // Advance the location for output.
      __ add(Operand(ebp, kRegisterOutput),
             Immediate(num_saved_registers_ * kPointerSize));

      // Prepare eax to initialize registers with its value in the next run.
      __ mov(eax, Operand(ebp, kInputStartMinusOne));

      if (global_with_zero_length_check()) {
        // Special case for zero-length matches.
        // edx: capture start index
        __ cmp(edi, edx);
        // Not a zero-length match, restart.
        __ j(not_equal, &load_char_start_regexp);
        // edi (offset from the end) is zero if we already reached the end.
        __ test(edi, edi);
        __ j(zero, &exit_label_, Label::kNear);
        // Advance current position after a zero-length match.
        if (mode_ == UC16) {
          __ add(edi, Immediate(2));
        } else {
          __ inc(edi);
        }
      }

      __ jmp(&load_char_start_regexp);
    } else {
      __ mov(eax, Immediate(SUCCESS));
    }
  }

  __ bind(&exit_label_);
  if (global()) {
    // Return the number of successful captures.
    __ mov(eax, Operand(ebp, kSuccessfulCaptures));
  }

  __ bind(&return_eax);
  // 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, eax);
    // If returning non-zero, we should end execution with the given
    // result as return value.
    __ j(not_zero, &return_eax);

    __ 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 = 3;
    __ PrepareCallCFunction(num_arguments, ebx);
    __ mov(Operand(esp, 2 * kPointerSize),
           Immediate(ExternalReference::isolate_address()));
    __ 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(masm_->isolate());
    __ 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, 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(&return_eax);
  }

  CodeDesc code_desc;
  masm_->GetCode(&code_desc);
  Handle<Code> code =
      masm_->isolate()->factory()->NewCode(code_desc,
                                           Code::ComputeFlags(Code::REGEXP),
                                           masm_->CodeObject());
  PROFILE(masm_->isolate(), RegExpCodeCreateEvent(*code, *source));
  return Handle<HeapObject>::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)  {
  Label after_position;
  __ cmp(edi, -by * char_size());
  __ j(greater_equal, &after_position, Label::kNear);
  __ 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));
}


bool RegExpMacroAssemblerIA32::Succeed() {
  __ jmp(&success_label_);
  return global();
}


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(masm_->isolate());
  __ 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) {
  Isolate* isolate = frame_entry<Isolate*>(re_frame, kIsolate);
  ASSERT(isolate == Isolate::Current());
  if (isolate->stack_guard()->IsStackOverflow()) {
    isolate->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(isolate);
  Handle<Code> code_handle(re_code);

  Handle<String> subject(frame_entry<String*>(re_frame, kInputString));

  // Current string.
  bool is_ascii = subject->IsAsciiRepresentationUnderneath();

  ASSERT(re_code->instruction_start() <= *return_address);
  ASSERT(*return_address <=
      re_code->instruction_start() + re_code->instruction_size());

  MaybeObject* result = Execution::HandleStackGuardInterrupt(isolate);

  if (*code_handle != re_code) {  // Return address no longer valid
    int delta = code_handle->address() - re_code->address();
    // Overwrite the return address on the stack.
    *return_address += delta;
  }

  if (result->IsException()) {
    return EXCEPTION;
  }

  Handle<String> subject_tmp = subject;
  int slice_offset = 0;

  // Extract the underlying string and the slice offset.
  if (StringShape(*subject_tmp).IsCons()) {
    subject_tmp = Handle<String>(ConsString::cast(*subject_tmp)->first());
  } else if (StringShape(*subject_tmp).IsSliced()) {
    SlicedString* slice = SlicedString::cast(*subject_tmp);
    subject_tmp = Handle<String>(slice->parent());
    slice_offset = slice->offset();
  }

  // String might have changed.
  if (subject_tmp->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_tmp).IsSequential() ||
      StringShape(*subject_tmp).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_tmp,
                                                    start_index + slice_offset);

  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 = static_cast<int>(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;
  } else if (frame_entry<const String*>(re_frame, kInputString) != *subject) {
    // Subject string might have been a ConsString that underwent
    // short-circuiting during GC. That will not change start_address but
    // will change pointer inside the subject handle.
    frame_entry<const String*>(re_frame, kInputString) = *subject;
  }

  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) {
  if (condition < 0) {  // No condition
    if (to == NULL) {
      Backtrack();
      return;
    }
    __ jmp(to);
    return;
  }
  if (to == NULL) {
    __ j(condition, &backtrack_label_);
    return;
  }
  __ j(condition, to);
}


void RegExpMacroAssemblerIA32::SafeCall(Label* to) {
  Label return_to;
  __ push(Immediate::CodeRelativeOffset(&return_to));
  __ jmp(to);
  __ bind(&return_to);
}


void RegExpMacroAssemblerIA32::SafeReturn() {
  __ pop(ebx);
  __ add(ebx, Immediate(masm_->CodeObject()));
  __ jmp(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(backtrack_stackpointer(), Immediate(kPointerSize));
  __ mov(Operand(backtrack_stackpointer(), 0), source);
}


void RegExpMacroAssemblerIA32::Push(Immediate value) {
  // Notice: This updates flags, unlike normal Push.
  __ sub(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(backtrack_stackpointer(), Immediate(kPointerSize));
}


void RegExpMacroAssemblerIA32::CheckPreemption() {
  // Check for preemption.
  Label no_preempt;
  ExternalReference stack_limit =
      ExternalReference::address_of_stack_limit(masm_->isolate());
  __ cmp(esp, Operand::StaticVariable(stack_limit));
  __ j(above, &no_preempt);

  SafeCall(&check_preempt_label_);

  __ bind(&no_preempt);
}


void RegExpMacroAssemblerIA32::CheckStackLimit() {
  Label no_stack_overflow;
  ExternalReference stack_limit =
      ExternalReference::address_of_regexp_stack_limit(masm_->isolate());
  __ 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
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