root/src/x64/regexp-macro-assembler-x64.cc

/* [<][>][^][v][top][bottom][index][help] */

DEFINITIONS

This source file includes following definitions.
  1. exit_label_
  2. stack_limit_slack
  3. AdvanceCurrentPosition
  4. AdvanceRegister
  5. Backtrack
  6. Bind
  7. CheckCharacter
  8. CheckCharacterGT
  9. CheckAtStart
  10. CheckNotAtStart
  11. CheckCharacterLT
  12. CheckCharacters
  13. CheckGreedyLoop
  14. CheckNotBackReferenceIgnoreCase
  15. CheckNotBackReference
  16. CheckNotCharacter
  17. CheckCharacterAfterAnd
  18. CheckNotCharacterAfterAnd
  19. CheckNotCharacterAfterMinusAnd
  20. CheckCharacterInRange
  21. CheckCharacterNotInRange
  22. CheckBitInTable
  23. CheckSpecialCharacterClass
  24. Fail
  25. GetCode
  26. GoTo
  27. IfRegisterGE
  28. IfRegisterLT
  29. IfRegisterEqPos
  30. Implementation
  31. LoadCurrentCharacter
  32. PopCurrentPosition
  33. PopRegister
  34. PushBacktrack
  35. PushCurrentPosition
  36. PushRegister
  37. ReadCurrentPositionFromRegister
  38. ReadStackPointerFromRegister
  39. SetCurrentPositionFromEnd
  40. SetRegister
  41. Succeed
  42. WriteCurrentPositionToRegister
  43. ClearRegisters
  44. WriteStackPointerToRegister
  45. CallCheckStackGuardState
  46. frame_entry
  47. CheckStackGuardState
  48. register_location
  49. CheckPosition
  50. BranchOrBacktrack
  51. SafeCall
  52. SafeCallTarget
  53. SafeReturn
  54. Push
  55. Push
  56. FixupCodeRelativePositions
  57. Push
  58. Pop
  59. Drop
  60. CheckPreemption
  61. CheckStackLimit
  62. 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_X64)

#include "serialize.h"
#include "unicode.h"
#include "log.h"
#include "regexp-stack.h"
#include "macro-assembler.h"
#include "regexp-macro-assembler.h"
#include "x64/regexp-macro-assembler-x64.h"

namespace v8 {
namespace internal {

#ifndef V8_INTERPRETED_REGEXP

/*
 * This assembler uses the following register assignment convention
 * - rdx : Currently loaded character(s) as ASCII or UC16.  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.
 * - rdi : Current position in input, as negative offset from end of string.
 *         Please notice that this is the byte offset, not the character
 *         offset!  Is always a 32-bit signed (negative) offset, but must be
 *         maintained sign-extended to 64 bits, since it is used as index.
 * - rsi : End of input (points to byte after last character in input),
 *         so that rsi+rdi points to the current character.
 * - rbp : Frame pointer.  Used to access arguments, local variables and
 *         RegExp registers.
 * - rsp : Points to tip of C stack.
 * - rcx : Points to tip of backtrack stack.  The backtrack stack contains
 *         only 32-bit values.  Most are offsets from some base (e.g., character
 *         positions from end of string or code location from Code* pointer).
 * - r8  : Code object pointer.  Used to convert between absolute and
 *         code-object-relative addresses.
 *
 * The registers rax, rbx, r9 and r11 are free to use for computations.
 * If changed to use r12+, they should be saved as callee-save registers.
 * The macro assembler special registers r12 and r13 (kSmiConstantRegister,
 * kRootRegister) aren't special during execution of RegExp code (they don't
 * hold the values assumed when creating JS code), so no Smi or Root related
 * macro operations can be used.
 *
 * Each call to a C++ method should retain these registers.
 *
 * The stack will have the following content, in some order, indexable from the
 * frame pointer (see, e.g., kStackHighEnd):
 *    - 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 (input string)
 *    - return address
 *    - backup of callee save registers (rbx, possibly rsi and rdi).
 *    - success counter      (only useful for global regexp to count matches)
 *    - Offset of location before start of input (effectively character
 *      position -1).  Used to initialize capture registers to a non-position.
 *    - At start of string (if 1, we are starting at the start of the
 *      string, otherwise 0)
 *    - register 0  rbp[-n]   (Only positions must be stored in the first
 *    - register 1  rbp[-n-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 uninitialized.
 *
 * The first seven values must be provided by the calling code by
 * calling the code's entry address cast to a function pointer with the
 * following 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_))

RegExpMacroAssemblerX64::RegExpMacroAssemblerX64(
    Mode mode,
    int registers_to_save,
    Zone* zone)
    : NativeRegExpMacroAssembler(zone),
      masm_(Isolate::Current(), NULL, kRegExpCodeSize),
      no_root_array_scope_(&masm_),
      code_relative_fixup_positions_(4, zone),
      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 when we know more.
  __ bind(&start_label_);  // And then continue from here.
}


RegExpMacroAssemblerX64::~RegExpMacroAssemblerX64() {
  // 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 RegExpMacroAssemblerX64::stack_limit_slack()  {
  return RegExpStack::kStackLimitSlack;
}


void RegExpMacroAssemblerX64::AdvanceCurrentPosition(int by) {
  if (by != 0) {
    __ addq(rdi, Immediate(by * char_size()));
  }
}


void RegExpMacroAssemblerX64::AdvanceRegister(int reg, int by) {
  ASSERT(reg >= 0);
  ASSERT(reg < num_registers_);
  if (by != 0) {
    __ addq(register_location(reg), Immediate(by));
  }
}


void RegExpMacroAssemblerX64::Backtrack() {
  CheckPreemption();
  // Pop Code* offset from backtrack stack, add Code* and jump to location.
  Pop(rbx);
  __ addq(rbx, code_object_pointer());
  __ jmp(rbx);
}


void RegExpMacroAssemblerX64::Bind(Label* label) {
  __ bind(label);
}


void RegExpMacroAssemblerX64::CheckCharacter(uint32_t c, Label* on_equal) {
  __ cmpl(current_character(), Immediate(c));
  BranchOrBacktrack(equal, on_equal);
}


void RegExpMacroAssemblerX64::CheckCharacterGT(uc16 limit, Label* on_greater) {
  __ cmpl(current_character(), Immediate(limit));
  BranchOrBacktrack(greater, on_greater);
}


void RegExpMacroAssemblerX64::CheckAtStart(Label* on_at_start) {
  Label not_at_start;
  // Did we start the match at the start of the string at all?
  __ cmpl(Operand(rbp, kStartIndex), Immediate(0));
  BranchOrBacktrack(not_equal, &not_at_start);
  // If we did, are we still at the start of the input?
  __ lea(rax, Operand(rsi, rdi, times_1, 0));
  __ cmpq(rax, Operand(rbp, kInputStart));
  BranchOrBacktrack(equal, on_at_start);
  __ bind(&not_at_start);
}


void RegExpMacroAssemblerX64::CheckNotAtStart(Label* on_not_at_start) {
  // Did we start the match at the start of the string at all?
  __ cmpl(Operand(rbp, kStartIndex), Immediate(0));
  BranchOrBacktrack(not_equal, on_not_at_start);
  // If we did, are we still at the start of the input?
  __ lea(rax, Operand(rsi, rdi, times_1, 0));
  __ cmpq(rax, Operand(rbp, kInputStart));
  BranchOrBacktrack(not_equal, on_not_at_start);
}


void RegExpMacroAssemblerX64::CheckCharacterLT(uc16 limit, Label* on_less) {
  __ cmpl(current_character(), Immediate(limit));
  BranchOrBacktrack(less, on_less);
}


void RegExpMacroAssemblerX64::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.
    __ cmpl(rdi, 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(rsi, rdi, times_1, byte_offset),
            Immediate(static_cast<int8_t>(str[0])));
  } else {
    // Don't use 16-bit immediate. The size changing prefix throws off
    // pre-decoding.
    __ movzxwl(rax,
               Operand(rsi, rdi, times_1, byte_offset));
    __ cmpl(rax, Immediate(static_cast<int32_t>(str[0])));
  }
  BranchOrBacktrack(not_equal, on_failure);

  __ lea(rbx, Operand(rsi, rdi, times_1, 0));
  for (int i = 1, n = str.length(); i < n; ) {
    if (mode_ == ASCII) {
      if (i + 8 <= n) {
        uint64_t combined_chars =
            (static_cast<uint64_t>(str[i + 0]) << 0) ||
            (static_cast<uint64_t>(str[i + 1]) << 8) ||
            (static_cast<uint64_t>(str[i + 2]) << 16) ||
            (static_cast<uint64_t>(str[i + 3]) << 24) ||
            (static_cast<uint64_t>(str[i + 4]) << 32) ||
            (static_cast<uint64_t>(str[i + 5]) << 40) ||
            (static_cast<uint64_t>(str[i + 6]) << 48) ||
            (static_cast<uint64_t>(str[i + 7]) << 56);
        __ movq(rax, combined_chars, RelocInfo::NONE);
        __ cmpq(rax, Operand(rbx, byte_offset + i));
        i += 8;
      } else if (i + 4 <= n) {
        uint32_t 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);
        __ cmpl(Operand(rbx, byte_offset + i), Immediate(combined_chars));
        i += 4;
      } else {
        __ cmpb(Operand(rbx, byte_offset + i),
                Immediate(static_cast<int8_t>(str[i])));
        i++;
      }
    } else {
      ASSERT(mode_ == UC16);
      if (i + 4 <= n) {
        uint64_t combined_chars = *reinterpret_cast<const uint64_t*>(&str[i]);
        __ movq(rax, combined_chars, RelocInfo::NONE);
        __ cmpq(rax,
                Operand(rsi, rdi, times_1, byte_offset + i * sizeof(uc16)));
        i += 4;
      } else if (i + 2 <= n) {
        uint32_t combined_chars = *reinterpret_cast<const uint32_t*>(&str[i]);
        __ cmpl(Operand(rsi, rdi, times_1, byte_offset + i * sizeof(uc16)),
                Immediate(combined_chars));
        i += 2;
      } else {
        __ movzxwl(rax,
                   Operand(rsi, rdi, times_1, byte_offset + i * sizeof(uc16)));
        __ cmpl(rax, Immediate(str[i]));
        i++;
      }
    }
    BranchOrBacktrack(not_equal, on_failure);
  }
}


void RegExpMacroAssemblerX64::CheckGreedyLoop(Label* on_equal) {
  Label fallthrough;
  __ cmpl(rdi, Operand(backtrack_stackpointer(), 0));
  __ j(not_equal, &fallthrough);
  Drop();
  BranchOrBacktrack(no_condition, on_equal);
  __ bind(&fallthrough);
}


void RegExpMacroAssemblerX64::CheckNotBackReferenceIgnoreCase(
    int start_reg,
    Label* on_no_match) {
  Label fallthrough;
  __ movq(rdx, register_location(start_reg));  // Offset of start of capture
  __ movq(rbx, register_location(start_reg + 1));  // Offset of end of capture
  __ subq(rbx, rdx);  // Length of capture.

  // -----------------------
  // rdx  = Start offset of capture.
  // rbx = Length of capture

  // If length is negative, this code will fail (it's a symptom of a partial or
  // illegal capture where start of capture after end of capture).
  // This must not happen (no back-reference can reference a capture that wasn't
  // closed before in the reg-exp, and we must not generate code that can cause
  // this condition).

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

  // -----------------------
  // rdx - Start of capture
  // rbx - length of capture
  // Check that there are sufficient characters left in the input.
  __ movl(rax, rdi);
  __ addl(rax, rbx);
  BranchOrBacktrack(greater, on_no_match);

  if (mode_ == ASCII) {
    Label loop_increment;
    if (on_no_match == NULL) {
      on_no_match = &backtrack_label_;
    }

    __ lea(r9, Operand(rsi, rdx, times_1, 0));
    __ lea(r11, Operand(rsi, rdi, times_1, 0));
    __ addq(rbx, r9);  // End of capture
    // ---------------------
    // r11 - current input character address
    // r9 - current capture character address
    // rbx - end of capture

    Label loop;
    __ bind(&loop);
    __ movzxbl(rdx, Operand(r9, 0));
    __ movzxbl(rax, Operand(r11, 0));
    // al - input character
    // dl - capture character
    __ cmpb(rax, rdx);
    __ j(equal, &loop_increment);

    // Mismatch, try case-insensitive match (converting letters to lower-case).
    // I.e., if or-ing with 0x20 makes values equal and in range 'a'-'z', it's
    // a match.
    __ or_(rax, Immediate(0x20));  // Convert match character to lower-case.
    __ or_(rdx, Immediate(0x20));  // Convert capture character to lower-case.
    __ cmpb(rax, rdx);
    __ j(not_equal, on_no_match);  // Definitely not equal.
    __ subb(rax, Immediate('a'));
    __ cmpb(rax, Immediate('z' - 'a'));
    __ j(above, on_no_match);  // Weren't letters anyway.

    __ bind(&loop_increment);
    // Increment pointers into match and capture strings.
    __ addq(r11, Immediate(1));
    __ addq(r9, Immediate(1));
    // Compare to end of capture, and loop if not done.
    __ cmpq(r9, rbx);
    __ j(below, &loop);

    // Compute new value of character position after the matched part.
    __ movq(rdi, r11);
    __ subq(rdi, rsi);
  } else {
    ASSERT(mode_ == UC16);
    // Save important/volatile registers before calling C function.
#ifndef _WIN64
    // Caller save on Linux and callee save in Windows.
    __ push(rsi);
    __ push(rdi);
#endif
    __ push(backtrack_stackpointer());

    static const int num_arguments = 4;
    __ PrepareCallCFunction(num_arguments);

    // Put arguments into parameter registers. 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
#ifdef _WIN64
    // Compute and set byte_offset1 (start of capture).
    __ lea(rcx, Operand(rsi, rdx, times_1, 0));
    // Set byte_offset2.
    __ lea(rdx, Operand(rsi, rdi, times_1, 0));
    // Set byte_length.
    __ movq(r8, rbx);
    // Isolate.
    __ LoadAddress(r9, ExternalReference::isolate_address());
#else  // AMD64 calling convention
    // Compute byte_offset2 (current position = rsi+rdi).
    __ lea(rax, Operand(rsi, rdi, times_1, 0));
    // Compute and set byte_offset1 (start of capture).
    __ lea(rdi, Operand(rsi, rdx, times_1, 0));
    // Set byte_offset2.
    __ movq(rsi, rax);
    // Set byte_length.
    __ movq(rdx, rbx);
    // Isolate.
    __ LoadAddress(rcx, ExternalReference::isolate_address());
#endif

    { // NOLINT: Can't find a way to open this scope without confusing the
      // linter.
      AllowExternalCallThatCantCauseGC scope(&masm_);
      ExternalReference compare =
          ExternalReference::re_case_insensitive_compare_uc16(masm_.isolate());
      __ CallCFunction(compare, num_arguments);
    }

    // Restore original values before reacting on result value.
    __ Move(code_object_pointer(), masm_.CodeObject());
    __ pop(backtrack_stackpointer());
#ifndef _WIN64
    __ pop(rdi);
    __ pop(rsi);
#endif

    // Check if function returned non-zero for success or zero for failure.
    __ testq(rax, rax);
    BranchOrBacktrack(zero, on_no_match);
    // On success, increment position by length of capture.
    // Requires that rbx is callee save (true for both Win64 and AMD64 ABIs).
    __ addq(rdi, rbx);
  }
  __ bind(&fallthrough);
}


void RegExpMacroAssemblerX64::CheckNotBackReference(
    int start_reg,
    Label* on_no_match) {
  Label fallthrough;

  // Find length of back-referenced capture.
  __ movq(rdx, register_location(start_reg));
  __ movq(rax, register_location(start_reg + 1));
  __ subq(rax, rdx);  // Length to check.

  // Fail on partial or illegal capture (start of capture after end of capture).
  // This must not happen (no back-reference can reference a capture that wasn't
  // closed before in the reg-exp).
  __ Check(greater_equal, "Invalid capture referenced");

  // Succeed on empty capture (including non-participating capture)
  __ j(equal, &fallthrough);

  // -----------------------
  // rdx - Start of capture
  // rax - length of capture

  // Check that there are sufficient characters left in the input.
  __ movl(rbx, rdi);
  __ addl(rbx, rax);
  BranchOrBacktrack(greater, on_no_match);

  // Compute pointers to match string and capture string
  __ lea(rbx, Operand(rsi, rdi, times_1, 0));  // Start of match.
  __ addq(rdx, rsi);  // Start of capture.
  __ lea(r9, Operand(rdx, rax, times_1, 0));  // End of capture

  // -----------------------
  // rbx - current capture character address.
  // rbx - current input character address .
  // r9 - end of input to match (capture length after rbx).

  Label loop;
  __ bind(&loop);
  if (mode_ == ASCII) {
    __ movzxbl(rax, Operand(rdx, 0));
    __ cmpb(rax, Operand(rbx, 0));
  } else {
    ASSERT(mode_ == UC16);
    __ movzxwl(rax, Operand(rdx, 0));
    __ cmpw(rax, Operand(rbx, 0));
  }
  BranchOrBacktrack(not_equal, on_no_match);
  // Increment pointers into capture and match string.
  __ addq(rbx, Immediate(char_size()));
  __ addq(rdx, Immediate(char_size()));
  // Check if we have reached end of match area.
  __ cmpq(rdx, r9);
  __ j(below, &loop);

  // Success.
  // Set current character position to position after match.
  __ movq(rdi, rbx);
  __ subq(rdi, rsi);

  __ bind(&fallthrough);
}


void RegExpMacroAssemblerX64::CheckNotCharacter(uint32_t c,
                                                Label* on_not_equal) {
  __ cmpl(current_character(), Immediate(c));
  BranchOrBacktrack(not_equal, on_not_equal);
}


void RegExpMacroAssemblerX64::CheckCharacterAfterAnd(uint32_t c,
                                                     uint32_t mask,
                                                     Label* on_equal) {
  if (c == 0) {
    __ testl(current_character(), Immediate(mask));
  } else {
    __ movl(rax, Immediate(mask));
    __ and_(rax, current_character());
    __ cmpl(rax, Immediate(c));
  }
  BranchOrBacktrack(equal, on_equal);
}


void RegExpMacroAssemblerX64::CheckNotCharacterAfterAnd(uint32_t c,
                                                        uint32_t mask,
                                                        Label* on_not_equal) {
  if (c == 0) {
    __ testl(current_character(), Immediate(mask));
  } else {
    __ movl(rax, Immediate(mask));
    __ and_(rax, current_character());
    __ cmpl(rax, Immediate(c));
  }
  BranchOrBacktrack(not_equal, on_not_equal);
}


void RegExpMacroAssemblerX64::CheckNotCharacterAfterMinusAnd(
    uc16 c,
    uc16 minus,
    uc16 mask,
    Label* on_not_equal) {
  ASSERT(minus < String::kMaxUtf16CodeUnit);
  __ lea(rax, Operand(current_character(), -minus));
  __ and_(rax, Immediate(mask));
  __ cmpl(rax, Immediate(c));
  BranchOrBacktrack(not_equal, on_not_equal);
}


void RegExpMacroAssemblerX64::CheckCharacterInRange(
    uc16 from,
    uc16 to,
    Label* on_in_range) {
  __ leal(rax, Operand(current_character(), -from));
  __ cmpl(rax, Immediate(to - from));
  BranchOrBacktrack(below_equal, on_in_range);
}


void RegExpMacroAssemblerX64::CheckCharacterNotInRange(
    uc16 from,
    uc16 to,
    Label* on_not_in_range) {
  __ leal(rax, Operand(current_character(), -from));
  __ cmpl(rax, Immediate(to - from));
  BranchOrBacktrack(above, on_not_in_range);
}


void RegExpMacroAssemblerX64::CheckBitInTable(
    Handle<ByteArray> table,
    Label* on_bit_set) {
  __ Move(rax, table);
  Register index = current_character();
  if (mode_ != ASCII || kTableMask != String::kMaxAsciiCharCode) {
    __ movq(rbx, current_character());
    __ and_(rbx, Immediate(kTableMask));
    index = rbx;
  }
  __ cmpb(FieldOperand(rax, index, times_1, ByteArray::kHeaderSize),
          Immediate(0));
  BranchOrBacktrack(not_equal, on_bit_set);
}


bool RegExpMacroAssemblerX64::CheckSpecialCharacterClass(uc16 type,
                                                         Label* on_no_match) {
  // Range checks (c in min..max) are generally implemented by an unsigned
  // (c - min) <= (max - min) check, using the sequence:
  //   lea(rax, Operand(current_character(), -min)) or sub(rax, Immediate(min))
  //   cmp(rax, Immediate(max - min))
  switch (type) {
  case 's':
    // Match space-characters
    if (mode_ == ASCII) {
      // ASCII space characters are '\t'..'\r' and ' '.
      Label success;
      __ cmpl(current_character(), Immediate(' '));
      __ j(equal, &success);
      // Check range 0x09..0x0d
      __ lea(rax, Operand(current_character(), -'\t'));
      __ cmpl(rax, Immediate('\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 ' '.
      __ cmpl(current_character(), Immediate(' '));
      BranchOrBacktrack(equal, on_no_match);
      __ lea(rax, Operand(current_character(), -'\t'));
      __ cmpl(rax, Immediate('\r' - '\t'));
      BranchOrBacktrack(below_equal, on_no_match);
      return true;
    }
    return false;
  case 'd':
    // Match ASCII digits ('0'..'9')
    __ lea(rax, Operand(current_character(), -'0'));
    __ cmpl(rax, Immediate('9' - '0'));
    BranchOrBacktrack(above, on_no_match);
    return true;
  case 'D':
    // Match non ASCII-digits
    __ lea(rax, Operand(current_character(), -'0'));
    __ cmpl(rax, Immediate('9' - '0'));
    BranchOrBacktrack(below_equal, on_no_match);
    return true;
  case '.': {
    // Match non-newlines (not 0x0a('\n'), 0x0d('\r'), 0x2028 and 0x2029)
    __ movl(rax, current_character());
    __ xor_(rax, Immediate(0x01));
    // See if current character is '\n'^1 or '\r'^1, i.e., 0x0b or 0x0c
    __ subl(rax, Immediate(0x0b));
    __ cmpl(rax, Immediate(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.
      __ subl(rax, Immediate(0x2028 - 0x0b));
      __ cmpl(rax, Immediate(0x2029 - 0x2028));
      BranchOrBacktrack(below_equal, on_no_match);
    }
    return true;
  }
  case 'n': {
    // Match newlines (0x0a('\n'), 0x0d('\r'), 0x2028 and 0x2029)
    __ movl(rax, current_character());
    __ xor_(rax, Immediate(0x01));
    // See if current character is '\n'^1 or '\r'^1, i.e., 0x0b or 0x0c
    __ subl(rax, Immediate(0x0b));
    __ cmpl(rax, Immediate(0x0c - 0x0b));
    if (mode_ == ASCII) {
      BranchOrBacktrack(above, on_no_match);
    } else {
      Label done;
      BranchOrBacktrack(below_equal, &done);
      // Compare original value to 0x2028 and 0x2029, using the already
      // computed (current_char ^ 0x01 - 0x0b). I.e., check for
      // 0x201d (0x2028 - 0x0b) or 0x201e.
      __ subl(rax, Immediate(0x2028 - 0x0b));
      __ cmpl(rax, Immediate(0x2029 - 0x2028));
      BranchOrBacktrack(above, on_no_match);
      __ bind(&done);
    }
    return true;
  }
  case 'w': {
    if (mode_ != ASCII) {
      // Table is 128 entries, so all ASCII characters can be tested.
      __ cmpl(current_character(), Immediate('z'));
      BranchOrBacktrack(above, on_no_match);
    }
    __ movq(rbx, ExternalReference::re_word_character_map());
    ASSERT_EQ(0, word_character_map[0]);  // Character '\0' is not a word char.
    __ testb(Operand(rbx, current_character(), times_1, 0),
             current_character());
    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.
      __ cmpl(current_character(), Immediate('z'));
      __ j(above, &done);
    }
    __ movq(rbx, ExternalReference::re_word_character_map());
    ASSERT_EQ(0, word_character_map[0]);  // Character '\0' is not a word char.
    __ testb(Operand(rbx, current_character(), times_1, 0),
             current_character());
    BranchOrBacktrack(not_zero, on_no_match);
    if (mode_ != ASCII) {
      __ bind(&done);
    }
    return true;
  }

  case '*':
    // Match any character.
    return true;
  // No custom implementation (yet): s(UC16), S(UC16).
  default:
    return false;
  }
}


void RegExpMacroAssemblerX64::Fail() {
  STATIC_ASSERT(FAILURE == 0);  // Return value for failure is zero.
  if (!global()) {
    __ Set(rax, FAILURE);
  }
  __ jmp(&exit_label_);
}


Handle<HeapObject> RegExpMacroAssemblerX64::GetCode(Handle<String> source) {
  Label return_rax;
  // 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
  // is generated.
  FrameScope scope(&masm_, StackFrame::MANUAL);

  // Actually emit code to start a new stack frame.
  __ push(rbp);
  __ movq(rbp, rsp);
  // Save parameters and callee-save registers. Order here should correspond
  //  to order of kBackup_ebx etc.
#ifdef _WIN64
  // MSVC passes arguments in rcx, rdx, r8, r9, with backing stack slots.
  // Store register parameters in pre-allocated stack slots,
  __ movq(Operand(rbp, kInputString), rcx);
  __ movq(Operand(rbp, kStartIndex), rdx);  // Passed as int32 in edx.
  __ movq(Operand(rbp, kInputStart), r8);
  __ movq(Operand(rbp, kInputEnd), r9);
  // Callee-save on Win64.
  __ push(rsi);
  __ push(rdi);
  __ push(rbx);
#else
  // GCC passes arguments in rdi, rsi, rdx, rcx, r8, r9 (and then on stack).
  // Push register parameters on stack for reference.
  ASSERT_EQ(kInputString, -1 * kPointerSize);
  ASSERT_EQ(kStartIndex, -2 * kPointerSize);
  ASSERT_EQ(kInputStart, -3 * kPointerSize);
  ASSERT_EQ(kInputEnd, -4 * kPointerSize);
  ASSERT_EQ(kRegisterOutput, -5 * kPointerSize);
  ASSERT_EQ(kNumOutputRegisters, -6 * kPointerSize);
  __ push(rdi);
  __ push(rsi);
  __ push(rdx);
  __ push(rcx);
  __ push(r8);
  __ push(r9);

  __ push(rbx);  // Callee-save
#endif

  __ 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());
  __ movq(rcx, rsp);
  __ movq(kScratchRegister, stack_limit);
  __ subq(rcx, Operand(kScratchRegister, 0));
  // 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.
  __ cmpq(rcx, Immediate(num_registers_ * kPointerSize));
  __ j(above_equal, &stack_ok);
  // Exit with OutOfMemory exception. There is not enough space on the stack
  // for our working registers.
  __ Set(rax, EXCEPTION);
  __ jmp(&return_rax);

  __ bind(&stack_limit_hit);
  __ Move(code_object_pointer(), masm_.CodeObject());
  CallCheckStackGuardState();  // Preserves no registers beside rbp and rsp.
  __ testq(rax, rax);
  // If returned value is non-zero, we exit with the returned value as result.
  __ j(not_zero, &return_rax);

  __ bind(&stack_ok);

  // Allocate space on stack for registers.
  __ subq(rsp, Immediate(num_registers_ * kPointerSize));
  // Load string length.
  __ movq(rsi, Operand(rbp, kInputEnd));
  // Load input position.
  __ movq(rdi, Operand(rbp, kInputStart));
  // Set up rdi to be negative offset from string end.
  __ subq(rdi, rsi);
  // Set rax to address of char before start of the string
  // (effectively string position -1).
  __ movq(rbx, Operand(rbp, kStartIndex));
  __ neg(rbx);
  if (mode_ == UC16) {
    __ lea(rax, Operand(rdi, rbx, times_2, -char_size()));
  } else {
    __ lea(rax, Operand(rdi, rbx, times_1, -char_size()));
  }
  // Store this value in a local variable, for use when clearing
  // position registers.
  __ movq(Operand(rbp, kInputStartMinusOne), rax);

#ifdef WIN32
  // Ensure that we have written to each stack page, in order. Skipping a page
  // on Windows can cause segmentation faults. Assuming page size is 4k.
  const int kPageSize = 4096;
  const int kRegistersPerPage = kPageSize / kPointerSize;
  for (int i = num_saved_registers_ + kRegistersPerPage - 1;
      i < num_registers_;
      i += kRegistersPerPage) {
    __ movq(register_location(i), rax);  // One write every page.
  }
#endif  // WIN32

  // Initialize code object pointer.
  __ Move(code_object_pointer(), masm_.CodeObject());

  Label load_char_start_regexp, start_regexp;
  // Load newline if index is at start, previous character otherwise.
  __ cmpl(Operand(rbp, kStartIndex), Immediate(0));
  __ j(not_equal, &load_char_start_regexp, Label::kNear);
  __ Set(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) {
    // 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) {
      __ Set(rcx, kRegisterZero);
      Label init_loop;
      __ bind(&init_loop);
      __ movq(Operand(rbp, rcx, times_1, 0), rax);
      __ subq(rcx, Immediate(kPointerSize));
      __ cmpq(rcx,
              Immediate(kRegisterZero - num_saved_registers_ * kPointerSize));
      __ j(greater, &init_loop);
    } else {  // Unroll the loop.
      for (int i = 0; i < num_saved_registers_; i++) {
        __ movq(register_location(i), rax);
      }
    }
  }

  // Initialize backtrack stack pointer.
  __ movq(backtrack_stackpointer(), Operand(rbp, 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
      __ movq(rdx, Operand(rbp, kStartIndex));
      __ movq(rbx, Operand(rbp, kRegisterOutput));
      __ movq(rcx, Operand(rbp, kInputEnd));
      __ subq(rcx, Operand(rbp, kInputStart));
      if (mode_ == UC16) {
        __ lea(rcx, Operand(rcx, rdx, times_2, 0));
      } else {
        __ addq(rcx, rdx);
      }
      for (int i = 0; i < num_saved_registers_; i++) {
        __ movq(rax, register_location(i));
        if (i == 0 && global_with_zero_length_check()) {
          // Keep capture start in rdx for the zero-length check later.
          __ movq(rdx, rax);
        }
        __ addq(rax, rcx);  // Convert to index from start, not end.
        if (mode_ == UC16) {
          __ sar(rax, Immediate(1));  // Convert byte index to character index.
        }
        __ movl(Operand(rbx, i * kIntSize), rax);
      }
    }

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

      __ movq(Operand(rbp, kNumOutputRegisters), rcx);
      // Advance the location for output.
      __ addq(Operand(rbp, kRegisterOutput),
              Immediate(num_saved_registers_ * kIntSize));

      // Prepare rax to initialize registers with its value in the next run.
      __ movq(rax, Operand(rbp, kInputStartMinusOne));

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

      __ jmp(&load_char_start_regexp);
    } else {
      __ movq(rax, Immediate(SUCCESS));
    }
  }

  __ bind(&exit_label_);
  if (global()) {
    // Return the number of successful captures.
    __ movq(rax, Operand(rbp, kSuccessfulCaptures));
  }

  __ bind(&return_rax);
#ifdef _WIN64
  // Restore callee save registers.
  __ lea(rsp, Operand(rbp, kLastCalleeSaveRegister));
  __ pop(rbx);
  __ pop(rdi);
  __ pop(rsi);
  // Stack now at rbp.
#else
  // Restore callee save register.
  __ movq(rbx, Operand(rbp, kBackup_rbx));
  // Skip rsp to rbp.
  __ movq(rsp, rbp);
#endif
  // Exit function frame, restore previous one.
  __ pop(rbp);
  __ 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(rdi);

    CallCheckStackGuardState();
    __ testq(rax, rax);
    // If returning non-zero, we should end execution with the given
    // result as return value.
    __ j(not_zero, &return_rax);

    // Restore registers.
    __ Move(code_object_pointer(), masm_.CodeObject());
    __ pop(rdi);
    __ pop(backtrack_stackpointer());
    // String might have moved: Reload esi from frame.
    __ movq(rsi, Operand(rbp, 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
#ifndef _WIN64
    // Callee-save in Microsoft 64-bit ABI, but not in AMD64 ABI.
    __ push(rsi);
    __ push(rdi);
#endif

    // Call GrowStack(backtrack_stackpointer())
    static const int num_arguments = 3;
    __ PrepareCallCFunction(num_arguments);
#ifdef _WIN64
    // Microsoft passes parameters in rcx, rdx, r8.
    // First argument, backtrack stackpointer, is already in rcx.
    __ lea(rdx, Operand(rbp, kStackHighEnd));  // Second argument
    __ LoadAddress(r8, ExternalReference::isolate_address());
#else
    // AMD64 ABI passes parameters in rdi, rsi, rdx.
    __ movq(rdi, backtrack_stackpointer());   // First argument.
    __ lea(rsi, Operand(rbp, kStackHighEnd));  // Second argument.
    __ LoadAddress(rdx, ExternalReference::isolate_address());
#endif
    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.
    __ testq(rax, rax);
    __ j(equal, &exit_with_exception);
    // Otherwise use return value as new stack pointer.
    __ movq(backtrack_stackpointer(), rax);
    // Restore saved registers and continue.
    __ Move(code_object_pointer(), masm_.CodeObject());
#ifndef _WIN64
    __ pop(rdi);
    __ pop(rsi);
#endif
    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.
    __ Set(rax, EXCEPTION);
    __ jmp(&return_rax);
  }

  FixupCodeRelativePositions();

  CodeDesc code_desc;
  masm_.GetCode(&code_desc);
  Isolate* isolate = ISOLATE;
  Handle<Code> code = isolate->factory()->NewCode(
      code_desc, Code::ComputeFlags(Code::REGEXP),
      masm_.CodeObject());
  PROFILE(isolate, RegExpCodeCreateEvent(*code, *source));
  return Handle<HeapObject>::cast(code);
}


void RegExpMacroAssemblerX64::GoTo(Label* to) {
  BranchOrBacktrack(no_condition, to);
}


void RegExpMacroAssemblerX64::IfRegisterGE(int reg,
                                           int comparand,
                                           Label* if_ge) {
  __ cmpq(register_location(reg), Immediate(comparand));
  BranchOrBacktrack(greater_equal, if_ge);
}


void RegExpMacroAssemblerX64::IfRegisterLT(int reg,
                                           int comparand,
                                           Label* if_lt) {
  __ cmpq(register_location(reg), Immediate(comparand));
  BranchOrBacktrack(less, if_lt);
}


void RegExpMacroAssemblerX64::IfRegisterEqPos(int reg,
                                              Label* if_eq) {
  __ cmpq(rdi, register_location(reg));
  BranchOrBacktrack(equal, if_eq);
}


RegExpMacroAssembler::IrregexpImplementation
    RegExpMacroAssemblerX64::Implementation() {
  return kX64Implementation;
}


void RegExpMacroAssemblerX64::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 RegExpMacroAssemblerX64::PopCurrentPosition() {
  Pop(rdi);
}


void RegExpMacroAssemblerX64::PopRegister(int register_index) {
  Pop(rax);
  __ movq(register_location(register_index), rax);
}


void RegExpMacroAssemblerX64::PushBacktrack(Label* label) {
  Push(label);
  CheckStackLimit();
}


void RegExpMacroAssemblerX64::PushCurrentPosition() {
  Push(rdi);
}


void RegExpMacroAssemblerX64::PushRegister(int register_index,
                                           StackCheckFlag check_stack_limit) {
  __ movq(rax, register_location(register_index));
  Push(rax);
  if (check_stack_limit) CheckStackLimit();
}


void RegExpMacroAssemblerX64::ReadCurrentPositionFromRegister(int reg) {
  __ movq(rdi, register_location(reg));
}


void RegExpMacroAssemblerX64::ReadStackPointerFromRegister(int reg) {
  __ movq(backtrack_stackpointer(), register_location(reg));
  __ addq(backtrack_stackpointer(), Operand(rbp, kStackHighEnd));
}


void RegExpMacroAssemblerX64::SetCurrentPositionFromEnd(int by) {
  Label after_position;
  __ cmpq(rdi, Immediate(-by * char_size()));
  __ j(greater_equal, &after_position, Label::kNear);
  __ movq(rdi, Immediate(-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 RegExpMacroAssemblerX64::SetRegister(int register_index, int to) {
  ASSERT(register_index >= num_saved_registers_);  // Reserved for positions!
  __ movq(register_location(register_index), Immediate(to));
}


bool RegExpMacroAssemblerX64::Succeed() {
  __ jmp(&success_label_);
  return global();
}


void RegExpMacroAssemblerX64::WriteCurrentPositionToRegister(int reg,
                                                             int cp_offset) {
  if (cp_offset == 0) {
    __ movq(register_location(reg), rdi);
  } else {
    __ lea(rax, Operand(rdi, cp_offset * char_size()));
    __ movq(register_location(reg), rax);
  }
}


void RegExpMacroAssemblerX64::ClearRegisters(int reg_from, int reg_to) {
  ASSERT(reg_from <= reg_to);
  __ movq(rax, Operand(rbp, kInputStartMinusOne));
  for (int reg = reg_from; reg <= reg_to; reg++) {
    __ movq(register_location(reg), rax);
  }
}


void RegExpMacroAssemblerX64::WriteStackPointerToRegister(int reg) {
  __ movq(rax, backtrack_stackpointer());
  __ subq(rax, Operand(rbp, kStackHighEnd));
  __ movq(register_location(reg), rax);
}


// Private methods:

void RegExpMacroAssemblerX64::CallCheckStackGuardState() {
  // This function call preserves no register values. Caller should
  // store anything volatile in a C call or overwritten by this function.
  static const int num_arguments = 3;
  __ PrepareCallCFunction(num_arguments);
#ifdef _WIN64
  // Second argument: Code* of self. (Do this before overwriting r8).
  __ movq(rdx, code_object_pointer());
  // Third argument: RegExp code frame pointer.
  __ movq(r8, rbp);
  // First argument: Next address on the stack (will be address of
  // return address).
  __ lea(rcx, Operand(rsp, -kPointerSize));
#else
  // Third argument: RegExp code frame pointer.
  __ movq(rdx, rbp);
  // Second argument: Code* of self.
  __ movq(rsi, code_object_pointer());
  // First argument: Next address on the stack (will be address of
  // return address).
  __ lea(rdi, Operand(rsp, -kPointerSize));
#endif
  ExternalReference stack_check =
      ExternalReference::re_check_stack_guard_state(masm_.isolate());
  __ CallCFunction(stack_check, 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 RegExpMacroAssemblerX64::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
    intptr_t 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 RegExpMacroAssemblerX64::register_location(int register_index) {
  ASSERT(register_index < (1<<30));
  if (num_registers_ <= register_index) {
    num_registers_ = register_index + 1;
  }
  return Operand(rbp, kRegisterZero - register_index * kPointerSize);
}


void RegExpMacroAssemblerX64::CheckPosition(int cp_offset,
                                            Label* on_outside_input) {
  __ cmpl(rdi, Immediate(-cp_offset * char_size()));
  BranchOrBacktrack(greater_equal, on_outside_input);
}


void RegExpMacroAssemblerX64::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 RegExpMacroAssemblerX64::SafeCall(Label* to) {
  __ call(to);
}


void RegExpMacroAssemblerX64::SafeCallTarget(Label* label) {
  __ bind(label);
  __ subq(Operand(rsp, 0), code_object_pointer());
}


void RegExpMacroAssemblerX64::SafeReturn() {
  __ addq(Operand(rsp, 0), code_object_pointer());
  __ ret(0);
}


void RegExpMacroAssemblerX64::Push(Register source) {
  ASSERT(!source.is(backtrack_stackpointer()));
  // Notice: This updates flags, unlike normal Push.
  __ subq(backtrack_stackpointer(), Immediate(kIntSize));
  __ movl(Operand(backtrack_stackpointer(), 0), source);
}


void RegExpMacroAssemblerX64::Push(Immediate value) {
  // Notice: This updates flags, unlike normal Push.
  __ subq(backtrack_stackpointer(), Immediate(kIntSize));
  __ movl(Operand(backtrack_stackpointer(), 0), value);
}


void RegExpMacroAssemblerX64::FixupCodeRelativePositions() {
  for (int i = 0, n = code_relative_fixup_positions_.length(); i < n; i++) {
    int position = code_relative_fixup_positions_[i];
    // The position succeeds a relative label offset from position.
    // Patch the relative offset to be relative to the Code object pointer
    // instead.
    int patch_position = position - kIntSize;
    int offset = masm_.long_at(patch_position);
    masm_.long_at_put(patch_position,
                       offset
                       + position
                       + Code::kHeaderSize
                       - kHeapObjectTag);
  }
  code_relative_fixup_positions_.Clear();
}


void RegExpMacroAssemblerX64::Push(Label* backtrack_target) {
  __ subq(backtrack_stackpointer(), Immediate(kIntSize));
  __ movl(Operand(backtrack_stackpointer(), 0), backtrack_target);
  MarkPositionForCodeRelativeFixup();
}


void RegExpMacroAssemblerX64::Pop(Register target) {
  ASSERT(!target.is(backtrack_stackpointer()));
  __ movsxlq(target, Operand(backtrack_stackpointer(), 0));
  // Notice: This updates flags, unlike normal Pop.
  __ addq(backtrack_stackpointer(), Immediate(kIntSize));
}


void RegExpMacroAssemblerX64::Drop() {
  __ addq(backtrack_stackpointer(), Immediate(kIntSize));
}


void RegExpMacroAssemblerX64::CheckPreemption() {
  // Check for preemption.
  Label no_preempt;
  ExternalReference stack_limit =
      ExternalReference::address_of_stack_limit(masm_.isolate());
  __ load_rax(stack_limit);
  __ cmpq(rsp, rax);
  __ j(above, &no_preempt);

  SafeCall(&check_preempt_label_);

  __ bind(&no_preempt);
}


void RegExpMacroAssemblerX64::CheckStackLimit() {
  Label no_stack_overflow;
  ExternalReference stack_limit =
      ExternalReference::address_of_regexp_stack_limit(masm_.isolate());
  __ load_rax(stack_limit);
  __ cmpq(backtrack_stackpointer(), rax);
  __ j(above, &no_stack_overflow);

  SafeCall(&stack_overflow_label_);

  __ bind(&no_stack_overflow);
}


void RegExpMacroAssemblerX64::LoadCurrentCharacterUnchecked(int cp_offset,
                                                            int characters) {
  if (mode_ == ASCII) {
    if (characters == 4) {
      __ movl(current_character(), Operand(rsi, rdi, times_1, cp_offset));
    } else if (characters == 2) {
      __ movzxwl(current_character(), Operand(rsi, rdi, times_1, cp_offset));
    } else {
      ASSERT(characters == 1);
      __ movzxbl(current_character(), Operand(rsi, rdi, times_1, cp_offset));
    }
  } else {
    ASSERT(mode_ == UC16);
    if (characters == 2) {
      __ movl(current_character(),
              Operand(rsi, rdi, times_1, cp_offset * sizeof(uc16)));
    } else {
      ASSERT(characters == 1);
      __ movzxwl(current_character(),
                 Operand(rsi, rdi, times_1, cp_offset * sizeof(uc16)));
    }
  }
}

#undef __

#endif  // V8_INTERPRETED_REGEXP

}}  // namespace v8::internal

#endif  // V8_TARGET_ARCH_X64

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