regexp-macro-assembler-ia32.cc

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// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
#if V8_TARGET_ARCH_IA32
 
#include "src/regexp/ia32/regexp-macro-assembler-ia32.h"
 
#include "src/codegen/assembler-inl.h"
#include "src/codegen/macro-assembler.h"
#include "src/logging/log.h"
#include "src/objects/objects-inl.h"
#include "src/regexp/regexp-macro-assembler.h"
#include "src/regexp/regexp-stack.h"
#include "src/strings/unicode.h"
 
namespace v8 {
namespace internal {
 
/*
 * 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:
 *       - Address regexp       (address of the JSRegExp object; unused in
 *                               native code, passed to match signature of
 *                               the interpreter)
 *       - Isolate* isolate     (address of the current isolate)
 *       - direct_call          (if 1, direct call from JavaScript code, if 0
 *                               call through the runtime system)
 *       - 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
 *       - frame marker
 *       - 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
 *         string start - 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,
 *              int num_capture_registers,
 *              bool direct_call = false,
 *              Isolate* isolate
 *              Address regexp);
 */
 
#define __ ACCESS_MASM(masm_)
 
const int RegExpMacroAssemblerIA32::kRegExpCodeSize;
 
RegExpMacroAssemblerIA32::RegExpMacroAssemblerIA32(Isolate* isolate, Zone* zone,
                                                   Mode mode,
                                                   int registers_to_save)
    : NativeRegExpMacroAssembler(isolate, zone),
      masm_(std::make_unique<MacroAssembler>(
          isolate, CodeObjectRequired::kYes,
          NewAssemblerBuffer(kRegExpCodeSize))),
      no_root_array_scope_(masm_.get()),
      mode_(mode),
      num_registers_(registers_to_save),
      num_saved_registers_(registers_to_save),
      entry_label_(),
      start_label_(),
      success_label_(),
      backtrack_label_(),
      exit_label_() {
  DCHECK_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() {
  // 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();
  fallback_label_.Unuse();
}
 
int RegExpMacroAssemblerIA32::stack_limit_slack_slot_count() {
  return RegExpStack::kStackLimitSlackSlotCount;
}
 
void RegExpMacroAssemblerIA32::AdvanceCurrentPosition(int by) {
  if (by != 0) {
    __ add(edi, Immediate(by * char_size()));
  }
}
 
 
void RegExpMacroAssemblerIA32::AdvanceRegister(int reg, int by) {
  DCHECK_LE(0, reg);
  DCHECK_GT(num_registers_, reg);
  if (by != 0) {
    __ add(register_location(reg), Immediate(by));
  }
}
 
 
void RegExpMacroAssemblerIA32::Backtrack() {
  CheckPreemption();
  if (has_backtrack_limit()) {
    Label next;
    __ inc(Operand(ebp, kBacktrackCountOffset));
    __ cmp(Operand(ebp, kBacktrackCountOffset), Immediate(backtrack_limit()));
    __ j(not_equal, &next);
 
    // Backtrack limit exceeded.
    if (can_fallback()) {
      __ jmp(&fallback_label_);
    } else {
      // Can't fallback, so we treat it as a failed match.
      Fail();
    }
 
    __ bind(&next);
  }
  // Pop InstructionStream offset from backtrack stack, add InstructionStream
  // 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(base::uc16 limit,
                                                Label* on_greater) {
  __ cmp(current_character(), limit);
  BranchOrBacktrack(greater, on_greater);
}
 
void RegExpMacroAssemblerIA32::CheckAtStart(int cp_offset, Label* on_at_start) {
  __ lea(eax, Operand(edi, -char_size() + cp_offset * char_size()));
  __ cmp(eax, Operand(ebp, kStringStartMinusOneOffset));
  BranchOrBacktrack(equal, on_at_start);
}
 
void RegExpMacroAssemblerIA32::CheckNotAtStart(int cp_offset,
                                               Label* on_not_at_start) {
  __ lea(eax, Operand(edi, -char_size() + cp_offset * char_size()));
  __ cmp(eax, Operand(ebp, kStringStartMinusOneOffset));
  BranchOrBacktrack(not_equal, on_not_at_start);
}
 
void RegExpMacroAssemblerIA32::CheckCharacterLT(base::uc16 limit,
                                                Label* on_less) {
  __ cmp(current_character(), limit);
  BranchOrBacktrack(less, on_less);
}
 
void RegExpMacroAssemblerIA32::CheckGreedyLoop(Label* on_equal) {
  Label fallthrough;
  __ cmp(edi, Operand(backtrack_stackpointer(), 0));
  __ j(not_equal, &fallthrough);
  __ add(backtrack_stackpointer(), Immediate(kSystemPointerSize));  // Pop.
  BranchOrBacktrack(on_equal);
  __ bind(&fallthrough);
}
 
void RegExpMacroAssemblerIA32::CallCFunctionFromIrregexpCode(
    ExternalReference function, int num_arguments) {
  // Irregexp code must not set fast_c_call_caller_fp and fast_c_call_caller_pc
  // since
  //
  // 1. it may itself have been called using CallCFunction and nested calls are
  //    unsupported, and
  // 2. it may itself have been called directly from C where the frame pointer
  //    might not be set (-fomit-frame-pointer), and thus frame iteration would
  //    fail.
  //
  // See also: crbug.com/v8/12670#c17.
  __ CallCFunction(function, num_arguments, SetIsolateDataSlots::kNo);
}
 
void RegExpMacroAssemblerIA32::PushCallerSavedRegisters() {
  static_assert(backtrack_stackpointer() == ecx);
  static_assert(current_character() == edx);
  __ push(ecx);
  __ push(edx);
}
 
void RegExpMacroAssemblerIA32::PopCallerSavedRegisters() {
  __ pop(edx);
  __ pop(ecx);
}
 
void RegExpMacroAssemblerIA32::CheckNotBackReferenceIgnoreCase(
    int start_reg, bool read_backward, bool unicode, 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.
 
  // At this point, the capture registers are either both set or both cleared.
  // If the capture length is zero, then the capture is either empty or cleared.
  // Fall through in both cases.
  __ j(equal, &fallthrough);
 
  // Check that there are sufficient characters left in the input.
  if (read_backward) {
    __ mov(eax, Operand(ebp, kStringStartMinusOneOffset));
    __ add(eax, ebx);
    __ cmp(edi, eax);
    BranchOrBacktrack(less_equal, on_no_match);
  } else {
    __ mov(eax, edi);
    __ add(eax, ebx);
    BranchOrBacktrack(greater, on_no_match);
  }
 
  if (mode_ == LATIN1) {
    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.
    if (read_backward) {
      __ sub(edi, ebx);  // Offset by length when matching backwards.
    }
    __ 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?
    Label convert_capture;
    __ j(below_equal, &convert_capture);  // In range 'a'-'z'.
    // Latin-1: Check for values in range [224,254] but not 247.
    __ sub(ecx, Immediate(224 - 'a'));
    __ cmp(ecx, Immediate(254 - 224));
    __ j(above, &fail);  // Weren't Latin-1 letters.
    __ cmp(ecx, Immediate(247 - 224));  // Check for 247.
    __ j(equal, &fail);
    __ bind(&convert_capture);
    // 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(on_no_match);
 
    __ bind(&success);
    // Restore original value before continuing.
    __ pop(backtrack_stackpointer());
    // Drop original value of character position.
    __ add(esp, Immediate(kSystemPointerSize));
    // Compute new value of character position after the matched part.
    __ sub(edi, esi);
    if (read_backward) {
      // Subtract match length if we matched backward.
      __ add(edi, register_location(start_reg));
      __ sub(edi, register_location(start_reg + 1));
    }
  } else {
    DCHECK(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 * kSystemPointerSize),
           Immediate(ExternalReference::isolate_address(isolate())));
    // Set byte_length.
    __ mov(Operand(esp, 2 * kSystemPointerSize), ebx);
    // Set byte_offset2.
    // Found by adding negative string-end offset of current position (edi)
    // to end of string.
    __ add(edi, esi);
    if (read_backward) {
      __ sub(edi, ebx);  // Offset by length when matching backwards.
    }
    __ mov(Operand(esp, 1 * kSystemPointerSize), edi);
    // Set byte_offset1.
    // Start of capture, where edx already holds string-end negative offset.
    __ add(edx, esi);
    __ mov(Operand(esp, 0 * kSystemPointerSize), edx);
 
    {
      AllowExternalCallThatCantCauseGC scope(masm_.get());
      ExternalReference compare =
          unicode
              ? ExternalReference::re_case_insensitive_compare_unicode()
              : ExternalReference::re_case_insensitive_compare_non_unicode();
      CallCFunctionFromIrregexpCode(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, advance position by length of capture.
    if (read_backward) {
      __ sub(edi, ebx);
    } else {
      __ add(edi, ebx);
    }
  }
  __ bind(&fallthrough);
}
 
void RegExpMacroAssemblerIA32::CheckNotBackReference(int start_reg,
                                                     bool read_backward,
                                                     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.
 
  // At this point, the capture registers are either both set or both cleared.
  // If the capture length is zero, then the capture is either empty or cleared.
  // Fall through in both cases.
  __ j(equal, &fallthrough);
 
  // Check that there are sufficient characters left in the input.
  if (read_backward) {
    __ mov(ebx, Operand(ebp, kStringStartMinusOneOffset));
    __ add(ebx, eax);
    __ cmp(edi, ebx);
    BranchOrBacktrack(less_equal, on_no_match);
  } else {
    __ 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
  __ add(edx, esi);  // Start of capture.
  __ lea(ebx, Operand(esi, edi, times_1, 0));  // Start of match.
  if (read_backward) {
    __ sub(ebx, eax);  // Offset by length when matching backwards.
  }
  __ lea(ecx, Operand(eax, ebx, times_1, 0));  // End of match
 
  Label loop;
  __ bind(&loop);
  if (mode_ == LATIN1) {
    __ movzx_b(eax, Operand(edx, 0));
    __ cmpb_al(Operand(ebx, 0));
  } else {
    DCHECK(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(on_no_match);
 
  __ bind(&success);
  // Move current character position to position after match.
  __ mov(edi, ecx);
  __ sub(edi, esi);
  if (read_backward) {
    // Subtract match length if we matched backward.
    __ add(edi, register_location(start_reg));
    __ sub(edi, register_location(start_reg + 1));
  }
  // 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(
    base::uc16 c, base::uc16 minus, base::uc16 mask, Label* on_not_equal) {
  DCHECK_GT(String::kMaxUtf16CodeUnit, minus);
  __ 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(base::uc16 from,
                                                     base::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(
    base::uc16 from, base::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::CallIsCharacterInRangeArray(
    const ZoneList<CharacterRange>* ranges) {
  PushCallerSavedRegisters();
 
  static const int kNumArguments = 2;
  __ PrepareCallCFunction(kNumArguments, ecx);
 
  __ mov(Operand(esp, 0 * kSystemPointerSize), current_character());
  __ mov(Operand(esp, 1 * kSystemPointerSize), GetOrAddRangeArray(ranges));
 
  {
    // We have a frame (set up in GetCode), but the assembler doesn't know.
    FrameScope scope(masm_.get(), StackFrame::MANUAL);
    CallCFunctionFromIrregexpCode(
        ExternalReference::re_is_character_in_range_array(), kNumArguments);
  }
 
  PopCallerSavedRegisters();
}
 
bool RegExpMacroAssemblerIA32::CheckCharacterInRangeArray(
    const ZoneList<CharacterRange>* ranges, Label* on_in_range) {
  CallIsCharacterInRangeArray(ranges);
  __ or_(eax, eax);
  BranchOrBacktrack(not_zero, on_in_range);
  return true;
}
 
bool RegExpMacroAssemblerIA32::CheckCharacterNotInRangeArray(
    const ZoneList<CharacterRange>* ranges, Label* on_not_in_range) {
  CallIsCharacterInRangeArray(ranges);
  __ or_(eax, eax);
  BranchOrBacktrack(zero, on_not_in_range);
  return true;
}
 
void RegExpMacroAssemblerIA32::CheckBitInTable(
    Handle<ByteArray> table,
    Label* on_bit_set) {
  __ mov(eax, Immediate(table));
  Register index = current_character();
  if (mode_ != LATIN1 || kTableMask != String::kMaxOneByteCharCode) {
    __ mov(ebx, kTableSize - 1);
    __ and_(ebx, current_character());
    index = ebx;
  }
  __ cmpb(FieldOperand(eax, index, times_1, OFFSET_OF_DATA_START(ByteArray)),
          Immediate(0));
  BranchOrBacktrack(not_equal, on_bit_set);
}
 
void RegExpMacroAssemblerIA32::SkipUntilBitInTable(
    int cp_offset, Handle<ByteArray> table, Handle<ByteArray> nibble_table,
    int advance_by) {
  // TODO(pthier): Optimize. Table can be loaded outside of the loop.
  Label cont, again;
  Bind(&again);
  LoadCurrentCharacter(cp_offset, &cont, true);
  CheckBitInTable(table, &cont);
  AdvanceCurrentPosition(advance_by);
  GoTo(&again);
  Bind(&cont);
}
 
bool RegExpMacroAssemblerIA32::CheckSpecialClassRanges(
    StandardCharacterSet type, Label* on_no_match) {
  // Range checks (c in min..max) are generally implemented by an unsigned
  // (c - min) <= (max - min) check
  // TODO(jgruber): No custom implementation (yet): s(UC16), S(UC16).
  switch (type) {
    case StandardCharacterSet::kWhitespace:
      // Match space-characters.
      if (mode_ == LATIN1) {
        // One byte space characters are '\t'..'\r', ' ' and \u00a0.
        Label success;
        __ cmp(current_character(), ' ');
        __ j(equal, &success, Label::kNear);
        // Check range 0x09..0x0D.
        __ lea(eax, Operand(current_character(), -'\t'));
        __ cmp(eax, '\r' - '\t');
        __ j(below_equal, &success, Label::kNear);
        // \u00a0 (NBSP).
        __ cmp(eax, 0x00A0 - '\t');
        BranchOrBacktrack(not_equal, on_no_match);
        __ bind(&success);
        return true;
      }
      return false;
    case StandardCharacterSet::kNotWhitespace:
      // The emitted code for generic character classes is good enough.
      return false;
    case StandardCharacterSet::kDigit:
      // Match ASCII digits ('0'..'9').
      __ lea(eax, Operand(current_character(), -'0'));
      __ cmp(eax, '9' - '0');
      BranchOrBacktrack(above, on_no_match);
      return true;
    case StandardCharacterSet::kNotDigit:
      // Match non ASCII-digits.
      __ lea(eax, Operand(current_character(), -'0'));
      __ cmp(eax, '9' - '0');
      BranchOrBacktrack(below_equal, on_no_match);
      return true;
    case StandardCharacterSet::kLineTerminator:
      // 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_ == LATIN1) {
        BranchOrBacktrack(above, on_no_match);
      } else {
        Label done;
        BranchOrBacktrack(below_equal, &done);
        DCHECK_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;
    case StandardCharacterSet::kNotLineTerminator: {
      // 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 StandardCharacterSet::kWord: {
      if (mode_ != LATIN1) {
        // Table is 256 entries, so all Latin1 characters can be tested.
        __ cmp(current_character(), Immediate('z'));
        BranchOrBacktrack(above, on_no_match);
      }
      DCHECK_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(current_character(), times_1, word_map.address(),
                        RelocInfo::EXTERNAL_REFERENCE));
      BranchOrBacktrack(zero, on_no_match);
      return true;
    }
    case StandardCharacterSet::kNotWord: {
      Label done;
      if (mode_ != LATIN1) {
        // Table is 256 entries, so all Latin1 characters can be tested.
        __ cmp(current_character(), Immediate('z'));
        __ j(above, &done);
      }
      DCHECK_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(current_character(), times_1, word_map.address(),
                        RelocInfo::EXTERNAL_REFERENCE));
      BranchOrBacktrack(not_zero, on_no_match);
      if (mode_ != LATIN1) {
        __ bind(&done);
      }
      return true;
    }
  // Non-standard classes (with no syntactic shorthand) used internally.
  case StandardCharacterSet::kEverything:
    // Match any character.
    return true;
  }
}
 
void RegExpMacroAssemblerIA32::Fail() {
  static_assert(FAILURE == 0);  // Return value for failure is zero.
  if (!global()) {
    __ Move(eax, Immediate(FAILURE));
  }
  __ jmp(&exit_label_);
}
 
void RegExpMacroAssemblerIA32::LoadRegExpStackPointerFromMemory(Register dst) {
  ExternalReference ref =
      ExternalReference::address_of_regexp_stack_stack_pointer(isolate());
  __ mov(dst, __ ExternalReferenceAsOperand(ref, dst));
}
 
void RegExpMacroAssemblerIA32::StoreRegExpStackPointerToMemory(
    Register src, Register scratch) {
  ExternalReference ref =
      ExternalReference::address_of_regexp_stack_stack_pointer(isolate());
  __ mov(__ ExternalReferenceAsOperand(ref, scratch), src);
}
 
void RegExpMacroAssemblerIA32::PushRegExpBasePointer(Register stack_pointer,
                                                     Register scratch) {
  ExternalReference ref =
      ExternalReference::address_of_regexp_stack_memory_top_address(isolate());
  __ mov(scratch, __ ExternalReferenceAsOperand(ref, scratch));
  __ sub(scratch, stack_pointer);
  __ mov(Operand(ebp, kRegExpStackBasePointerOffset), scratch);
}
 
void RegExpMacroAssemblerIA32::PopRegExpBasePointer(Register stack_pointer_out,
                                                    Register scratch) {
  ExternalReference ref =
      ExternalReference::address_of_regexp_stack_memory_top_address(isolate());
  __ mov(scratch, Operand(ebp, kRegExpStackBasePointerOffset));
  __ mov(stack_pointer_out,
         __ ExternalReferenceAsOperand(ref, stack_pointer_out));
  __ sub(stack_pointer_out, scratch);
  StoreRegExpStackPointerToMemory(stack_pointer_out, scratch);
}
 
DirectHandle<HeapObject> RegExpMacroAssemblerIA32::GetCode(
    DirectHandle<String> source, RegExpFlags flags) {
  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_.get(), StackFrame::MANUAL);
 
  // Actually emit code to start a new stack frame. This pushes the frame type
  // marker into the stack slot at kFrameTypeOffset.
  static_assert(kFrameTypeOffset == -1 * kSystemPointerSize);
  __ EnterFrame(StackFrame::IRREGEXP);
 
  // Save callee-save registers. Order here should correspond to order of
  // kBackupEbxOffset etc.
  __ push(esi);
  __ push(edi);
  __ push(ebx);  // Callee-save on MacOS.
  static_assert(kLastCalleeSaveRegisterOffset == kBackupEbxOffset);
 
  static_assert(kSuccessfulCapturesOffset ==
                kLastCalleeSaveRegisterOffset - kSystemPointerSize);
  __ push(Immediate(0));  // Number of successful matches in a global regexp.
  static_assert(kStringStartMinusOneOffset ==
                kSuccessfulCapturesOffset - kSystemPointerSize);
  __ push(Immediate(0));  // Make room for "string start - 1" constant.
  static_assert(kBacktrackCountOffset ==
                kStringStartMinusOneOffset - kSystemPointerSize);
  __ push(Immediate(0));  // The backtrack counter.
  static_assert(kRegExpStackBasePointerOffset ==
                kBacktrackCountOffset - kSystemPointerSize);
  __ push(Immediate(0));  // The regexp stack base ptr.
 
  // Initialize backtrack stack pointer. It must not be clobbered from here on.
  // Note the backtrack_stackpointer is *not* callee-saved.
  static_assert(backtrack_stackpointer() == ecx);
  LoadRegExpStackPointerFromMemory(backtrack_stackpointer());
 
  // Store the regexp base pointer - we'll later restore it / write it to
  // memory when returning from this irregexp code object.
  PushRegExpBasePointer(backtrack_stackpointer(), eax);
 
  {
    // Check if we have space on the stack for registers.
    Label stack_limit_hit, stack_ok;
 
    ExternalReference stack_limit =
        ExternalReference::address_of_jslimit(isolate());
    __ mov(eax, esp);
    __ sub(eax, StaticVariable(stack_limit));
    Immediate extra_space_for_variables(num_registers_ * kSystemPointerSize);
 
    // 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(eax, extra_space_for_variables);
    __ 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);
    __ push(backtrack_stackpointer());
    CallCheckStackGuardState(ebx, extra_space_for_variables);
    __ pop(backtrack_stackpointer());
    __ 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, kStartIndexOffset));
 
  // Allocate space on stack for registers.
  __ AllocateStackSpace(num_registers_ * kSystemPointerSize);
  // Load string length.
  __ mov(esi, Operand(ebp, kInputEndOffset));
  // Load input position.
  __ mov(edi, Operand(ebp, kInputStartOffset));
  // 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, kStringStartMinusOneOffset), eax);
 
  Label load_char_start_regexp;
  {
    Label start_regexp;
 
    // Load newline if index is at start, previous character otherwise.
    __ cmp(Operand(ebp, kStartIndexOffset), 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) {
      DCHECK_EQ(ecx, backtrack_stackpointer());
      __ push(ecx);
      __ mov(ecx, kRegisterZeroOffset);
      Label init_loop;
      __ bind(&init_loop);
      __ mov(Operand(ebp, ecx, times_1, 0), eax);
      __ sub(ecx, Immediate(kSystemPointerSize));
      __ cmp(ecx,
             kRegisterZeroOffset - num_saved_registers_ * kSystemPointerSize);
      __ j(greater, &init_loop);
      __ pop(ecx);
    } else {  // Unroll the loop.
      for (int i = 0; i < num_saved_registers_; i++) {
        __ mov(register_location(i), eax);
      }
    }
  }
 
  __ 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, kRegisterOutputOffset));
      __ mov(ecx, Operand(ebp, kInputEndOffset));
      __ mov(edx, Operand(ebp, kStartIndexOffset));
      __ sub(ecx, Operand(ebp, kInputStartOffset));
      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 * kSystemPointerSize), eax);
      }
    }
 
    if (global()) {
      // Restart matching if the regular expression is flagged as global.
      // Increment success counter.
      __ inc(Operand(ebp, kSuccessfulCapturesOffset));
      // 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, kNumOutputRegistersOffset));
      __ 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, kNumOutputRegistersOffset), ecx);
      // Advance the location for output.
      __ add(Operand(ebp, kRegisterOutputOffset),
             Immediate(num_saved_registers_ * kSystemPointerSize));
 
      // Restore the original regexp stack pointer value (effectively, pop the
      // stored base pointer).
      PopRegExpBasePointer(backtrack_stackpointer(), ebx);
 
      Label reload_string_start_minus_one;
 
      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, &reload_string_start_minus_one);
        // 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.
        Label advance;
        __ bind(&advance);
        if (mode_ == UC16) {
          __ add(edi, Immediate(2));
        } else {
          __ inc(edi);
        }
        if (global_unicode()) CheckNotInSurrogatePair(0, &advance);
      }
 
      __ bind(&reload_string_start_minus_one);
      // Prepare eax to initialize registers with its value in the next run.
      // Must be immediately before the jump to avoid clobbering.
      __ mov(eax, Operand(ebp, kStringStartMinusOneOffset));
 
      __ 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, kSuccessfulCapturesOffset));
  }
 
  __ bind(&return_eax);
  // Restore the original regexp stack pointer value (effectively, pop the
  // stored base pointer).
  PopRegExpBasePointer(backtrack_stackpointer(), ebx);
 
  // Skip esp past regexp registers.
  __ lea(esp, Operand(ebp, kLastCalleeSaveRegisterOffset));
  // Restore callee-save registers.
  static_assert(kNumCalleeSaveRegisters == 3);
  static_assert(kBackupEsiOffset == -2 * kSystemPointerSize);
  static_assert(kBackupEdiOffset == -3 * kSystemPointerSize);
  static_assert(kBackupEbxOffset == -4 * kSystemPointerSize);
  __ pop(ebx);
  __ pop(edi);
  __ pop(esi);
 
  __ LeaveFrame(StackFrame::IRREGEXP);
  __ 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_);
 
    StoreRegExpStackPointerToMemory(backtrack_stackpointer(), edi);
 
    __ 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);
 
    LoadRegExpStackPointerFromMemory(backtrack_stackpointer());
 
    // String might have moved: Reload esi from frame.
    __ mov(esi, Operand(ebp, kInputEndOffset));
    SafeReturn();
  }
 
  // Backtrack stack overflow code.
  if (stack_overflow_label_.is_linked()) {
    SafeCallTarget(&stack_overflow_label_);
    // Reached if the backtrack-stack limit has been hit.
 
    // Save registers before calling C function.
    __ push(esi);
    __ push(edi);
 
    StoreRegExpStackPointerToMemory(backtrack_stackpointer(), edi);
 
    // Call GrowStack(isolate).
    static const int kNumArguments = 1;
    __ PrepareCallCFunction(kNumArguments, ebx);
    __ mov(Operand(esp, 0 * kSystemPointerSize),
           Immediate(ExternalReference::isolate_address(isolate())));
    CallCFunctionFromIrregexpCode(ExternalReference::re_grow_stack(),
                                  kNumArguments);
    // If return nullptr, 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);
  }
 
  if (fallback_label_.is_linked()) {
    __ bind(&fallback_label_);
    __ mov(eax, FALLBACK_TO_EXPERIMENTAL);
    __ jmp(&return_eax);
  }
 
  CodeDesc code_desc;
  masm_->GetCode(masm_->isolate(), &code_desc);
  Handle<Code> code =
      Factory::CodeBuilder(isolate(), code_desc, CodeKind::REGEXP)
          .set_self_reference(masm_->CodeObject())
          .set_empty_source_position_table()
          .Build();
  PROFILE(masm_->isolate(),
          RegExpCodeCreateEvent(Cast<AbstractCode>(code), source, flags));
  return Cast<HeapObject>(code);
}
 
void RegExpMacroAssemblerIA32::GoTo(Label* to) { BranchOrBacktrack(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::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);
  CheckStackLimit();
}
 
 
void RegExpMacroAssemblerIA32::PushRegister(int register_index,
                                            StackCheckFlag check_stack_limit) {
  __ mov(eax, register_location(register_index));
  Push(eax);
  if (check_stack_limit) {
    CheckStackLimit();
  } else if (V8_UNLIKELY(v8_flags.slow_debug_code)) {
    AssertAboveStackLimitMinusSlack();
  }
}
 
 
void RegExpMacroAssemblerIA32::ReadCurrentPositionFromRegister(int reg) {
  __ mov(edi, register_location(reg));
}
 
void RegExpMacroAssemblerIA32::WriteStackPointerToRegister(int reg) {
  ExternalReference stack_top_address =
      ExternalReference::address_of_regexp_stack_memory_top_address(isolate());
  __ mov(eax, __ ExternalReferenceAsOperand(stack_top_address, eax));
  __ sub(eax, backtrack_stackpointer());
  __ mov(register_location(reg), eax);
}
 
void RegExpMacroAssemblerIA32::ReadStackPointerFromRegister(int reg) {
  ExternalReference stack_top_address =
      ExternalReference::address_of_regexp_stack_memory_top_address(isolate());
  __ mov(backtrack_stackpointer(),
         __ ExternalReferenceAsOperand(stack_top_address,
                                       backtrack_stackpointer()));
  __ sub(backtrack_stackpointer(), register_location(reg));
}
 
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) {
  DCHECK(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) {
  DCHECK(reg_from <= reg_to);
  __ mov(eax, Operand(ebp, kStringStartMinusOneOffset));
  for (int reg = reg_from; reg <= reg_to; reg++) {
    __ mov(register_location(reg), eax);
  }
}
 
// Private methods:
 
void RegExpMacroAssemblerIA32::CallCheckStackGuardState(Register scratch,
                                                        Immediate extra_space) {
  static const int num_arguments = 4;
  __ PrepareCallCFunction(num_arguments, scratch);
  // Extra space for variables.
  __ mov(Operand(esp, 3 * kSystemPointerSize), extra_space);
  // RegExp code frame pointer.
  __ mov(Operand(esp, 2 * kSystemPointerSize), ebp);
  // InstructionStream of self.
  __ mov(Operand(esp, 1 * kSystemPointerSize), Immediate(masm_->CodeObject()));
  // Next address on the stack (will be address of return address).
  __ lea(eax, Operand(esp, -kSystemPointerSize));
  __ mov(Operand(esp, 0 * kSystemPointerSize), eax);
  ExternalReference check_stack_guard =
      ExternalReference::re_check_stack_guard_state();
  CallCFunctionFromIrregexpCode(check_stack_guard, num_arguments);
}
 
Operand RegExpMacroAssemblerIA32::StaticVariable(const ExternalReference& ext) {
  return Operand(ext.address(), RelocInfo::EXTERNAL_REFERENCE);
}
 
// 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_t>(re_frame + frame_offset));
}
 
 
template <typename T>
static T* frame_entry_address(Address re_frame, int frame_offset) {
  return reinterpret_cast<T*>(re_frame + frame_offset);
}
 
int RegExpMacroAssemblerIA32::CheckStackGuardState(Address* return_address,
                                                   Address raw_code,
                                                   Address re_frame,
                                                   uintptr_t extra_space) {
  Tagged<InstructionStream> re_code =
      Cast<InstructionStream>(Tagged<Object>(raw_code));
  return NativeRegExpMacroAssembler::CheckStackGuardState(
      frame_entry<Isolate*>(re_frame, kIsolateOffset),
      frame_entry<int>(re_frame, kStartIndexOffset),
      static_cast<RegExp::CallOrigin>(
          frame_entry<int>(re_frame, kDirectCallOffset)),
      return_address, re_code,
      frame_entry_address<Address>(re_frame, kInputStringOffset),
      frame_entry_address<const uint8_t*>(re_frame, kInputStartOffset),
      frame_entry_address<const uint8_t*>(re_frame, kInputEndOffset),
      extra_space);
}
 
Operand RegExpMacroAssemblerIA32::register_location(int register_index) {
  DCHECK(register_index < (1<<30));
  if (num_registers_ <= register_index) {
    num_registers_ = register_index + 1;
  }
  return Operand(ebp,
                 kRegisterZeroOffset - register_index * kSystemPointerSize);
}
 
 
void RegExpMacroAssemblerIA32::CheckPosition(int cp_offset,
                                             Label* on_outside_input) {
  if (cp_offset >= 0) {
    __ cmp(edi, -cp_offset * char_size());
    BranchOrBacktrack(greater_equal, on_outside_input);
  } else {
    __ lea(eax, Operand(edi, cp_offset * char_size()));
    __ cmp(eax, Operand(ebp, kStringStartMinusOneOffset));
    BranchOrBacktrack(less_equal, on_outside_input);
  }
}
 
void RegExpMacroAssemblerIA32::BranchOrBacktrack(Label* to) {
  if (to == nullptr) {
    Backtrack();
    return;
  }
  __ jmp(to);
}
 
void RegExpMacroAssemblerIA32::BranchOrBacktrack(Condition condition,
                                                 Label* to) {
  __ j(condition, to ? to : &backtrack_label_);
}
 
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) {
  DCHECK(source != backtrack_stackpointer());
  // Notice: This updates flags, unlike normal Push.
  __ sub(backtrack_stackpointer(), Immediate(kSystemPointerSize));
  __ mov(Operand(backtrack_stackpointer(), 0), source);
}
 
 
void RegExpMacroAssemblerIA32::Push(Immediate value) {
  // Notice: This updates flags, unlike normal Push.
  __ sub(backtrack_stackpointer(), Immediate(kSystemPointerSize));
  __ mov(Operand(backtrack_stackpointer(), 0), value);
}
 
 
void RegExpMacroAssemblerIA32::Pop(Register target) {
  DCHECK(target != backtrack_stackpointer());
  __ mov(target, Operand(backtrack_stackpointer(), 0));
  // Notice: This updates flags, unlike normal Pop.
  __ add(backtrack_stackpointer(), Immediate(kSystemPointerSize));
}
 
 
void RegExpMacroAssemblerIA32::CheckPreemption() {
  // Check for preemption.
  Label no_preempt;
  ExternalReference stack_limit =
      ExternalReference::address_of_jslimit(isolate());
  __ cmp(esp, 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_address(isolate());
  __ cmp(backtrack_stackpointer(), StaticVariable(stack_limit));
  __ j(above, &no_stack_overflow);
 
  SafeCall(&stack_overflow_label_);
 
  __ bind(&no_stack_overflow);
}
 
void RegExpMacroAssemblerIA32::AssertAboveStackLimitMinusSlack() {
  DCHECK(v8_flags.slow_debug_code);
  Label no_stack_overflow;
  ASM_CODE_COMMENT_STRING(masm_.get(), "AssertAboveStackLimitMinusSlack");
  auto l = ExternalReference::address_of_regexp_stack_limit_address(isolate());
  __ mov(eax, __ ExternalReferenceAsOperand(l, eax));
  __ sub(eax, Immediate(RegExpStack::kStackLimitSlackSize));
  __ cmp(backtrack_stackpointer(), eax);
  __ j(above, &no_stack_overflow);
  __ int3();
  __ bind(&no_stack_overflow);
}
 
void RegExpMacroAssemblerIA32::LoadCurrentCharacterUnchecked(int cp_offset,
                                                             int characters) {
  if (mode_ == LATIN1) {
    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 {
      DCHECK_EQ(1, characters);
      __ movzx_b(current_character(), Operand(esi, edi, times_1, cp_offset));
    }
  } else {
    DCHECK(mode_ == UC16);
    if (characters == 2) {
      __ mov(current_character(),
             Operand(esi, edi, times_1, cp_offset * sizeof(base::uc16)));
    } else {
      DCHECK_EQ(1, characters);
      __ movzx_w(current_character(),
                 Operand(esi, edi, times_1, cp_offset * sizeof(base::uc16)));
    }
  }
}
 
 
#undef __
 
}  // namespace internal
}  // namespace v8
 
#endif  // V8_TARGET_ARCH_IA32