regexp-macro-assembler-loong64.cc

Go to the documentation of this file.

// Copyright 2021 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_LOONG64
 
#include "src/regexp/loong64/regexp-macro-assembler-loong64.h"
 
#include "src/codegen/macro-assembler.h"
#include "src/heap/factory.h"
#include "src/logging/log.h"
#include "src/objects/code-inl.h"
#include "src/regexp/regexp-stack.h"
#include "src/snapshot/embedded/embedded-data-inl.h"
 
namespace v8 {
namespace internal {
 
/* clang-format off
 *
 * This assembler uses the following register assignment convention
 * - s0 : Unused.
 * - s1 : Pointer to current InstructionStream object including heap object tag.
 * - s2 : Current position in input, as negative offset from end of string.
 *        Please notice that this is the byte offset, not the character offset!
 * - s5 : Currently loaded character. Must be loaded using
 *        LoadCurrentCharacter before using any of the dispatch methods.
 * - s6 : Points to tip of backtrack stack
 * - s7 : End of input (points to byte after last character in input).
 * - fp : Frame pointer. Used to access arguments, local variables and
 *        RegExp registers.
 * - sp : Points to tip of C stack.
 *
 * The remaining registers are free for computations.
 * Each call to a public method should retain this convention.
 *
 * The stack will have the following structure:
 *
 *  - fp[80]  Isolate* isolate   (address of the current isolate)               kIsolateOffset
 *                                                                              kStackFrameHeaderOffset
 *  --- sp when called ---
 *  - fp[72]  ra                 Return from RegExp code (ra).                  kReturnAddressOffset
 *  - fp[64]  old-fp             Old fp, callee saved.
 *  - fp[0..63]  s0..s7          Callee-saved registers s0..s7.
 *  --- frame pointer ----
 *  - fp[-8]  frame marker
 *  - fp[-16] direct_call        (1 = direct call from JS, 0 = from runtime)    kDirectCallOffset
 *  - fp[-24] capture array size (may fit multiple sets of matches)             kNumOutputRegistersOffset
 *  - fp[-32] int* capture_array (int[num_saved_registers_], for output).       kRegisterOutputOffset
 *  - fp[-40] end of input       (address of end of string).                    kInputEndOffset
 *  - fp[-48] start of input     (address of first character in string).        kInputStartOffset
 *  - fp[-56] start index        (character index of start).                    kStartIndexOffset
 *  - fp[-64] void* input_string (location of a handle containing the string).  kInputStringOffset
 *  - fp[-72] success counter    (only for global regexps to count matches).    kSuccessfulCapturesOffset
 *  - fp[-80] Offset of location before start of input (effectively character   kStringStartMinusOneOffsetOffset
 *            position -1). Used to initialize capture registers to a
 *            non-position.
 *  --------- The following output registers are 32-bit values. ---------
 *  - fp[-88] register 0         (Only positions must be stored in the first    kRegisterZeroOffset
 *  -         register 1          num_saved_registers_ registers)
 *  -         ...
 *  -         register num_registers-1
 *  --- sp ---
 *
 * 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 start out as garbage.
 *
 * The data up to the return address must be placed there by the calling
 * code and the remaining arguments are passed in registers, e.g. 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);
 * The call is performed by NativeRegExpMacroAssembler::Execute()
 * (in regexp-macro-assembler.cc) via the GeneratedCode wrapper.
 *
 * clang-format on
 */
 
#define __ ACCESS_MASM(masm_)
 
RegExpMacroAssemblerLOONG64::RegExpMacroAssemblerLOONG64(Isolate* isolate,
                                                         Zone* zone, Mode mode,
                                                         int registers_to_save)
    : NativeRegExpMacroAssembler(isolate, zone),
      masm_(std::make_unique<MacroAssembler>(
          isolate, CodeObjectRequired::kYes,
          NewAssemblerBuffer(kInitialBufferSize))),
      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_(),
      internal_failure_label_() {
  DCHECK_EQ(0, registers_to_save % 2);
  __ jmp(&entry_label_);  // We'll write the entry code later.
  // If the code gets too big or corrupted, an internal exception will be
  // raised, and we will exit right away.
  __ bind(&internal_failure_label_);
  __ li(a0, Operand(FAILURE));
  __ Ret();
  __ bind(&start_label_);  // And then continue from here.
}
 
RegExpMacroAssemblerLOONG64::~RegExpMacroAssemblerLOONG64() {
  // 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();
  internal_failure_label_.Unuse();
  fallback_label_.Unuse();
}
 
int RegExpMacroAssemblerLOONG64::stack_limit_slack_slot_count() {
  return RegExpStack::kStackLimitSlackSlotCount;
}
 
void RegExpMacroAssemblerLOONG64::AdvanceCurrentPosition(int by) {
  if (by != 0) {
    __ Add_d(current_input_offset(), current_input_offset(),
             Operand(by * char_size()));
  }
}
 
void RegExpMacroAssemblerLOONG64::AdvanceRegister(int reg, int by) {
  DCHECK_LE(0, reg);
  DCHECK_GT(num_registers_, reg);
  if (by != 0) {
    __ Ld_d(a0, register_location(reg));
    __ Add_d(a0, a0, Operand(by));
    __ St_d(a0, register_location(reg));
  }
}
 
void RegExpMacroAssemblerLOONG64::Backtrack() {
  CheckPreemption();
  if (has_backtrack_limit()) {
    Label next;
    __ Ld_d(a0, MemOperand(frame_pointer(), kBacktrackCountOffset));
    __ Add_d(a0, a0, Operand(1));
    __ St_d(a0, MemOperand(frame_pointer(), kBacktrackCountOffset));
    __ Branch(&next, ne, a0, Operand(backtrack_limit()));
 
    // 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 Code offset from backtrack stack, add Code and jump to location.
  Pop(a0);
  __ Add_d(a0, a0, code_pointer());
  __ Jump(a0);
}
 
void RegExpMacroAssemblerLOONG64::Bind(Label* label) { __ bind(label); }
 
void RegExpMacroAssemblerLOONG64::CheckCharacter(uint32_t c, Label* on_equal) {
  BranchOrBacktrack(on_equal, eq, current_character(), Operand(c));
}
 
void RegExpMacroAssemblerLOONG64::CheckCharacterGT(base::uc16 limit,
                                                   Label* on_greater) {
  BranchOrBacktrack(on_greater, gt, current_character(), Operand(limit));
}
 
void RegExpMacroAssemblerLOONG64::CheckAtStart(int cp_offset,
                                               Label* on_at_start) {
  __ Ld_d(a1, MemOperand(frame_pointer(), kStringStartMinusOneOffset));
  __ Add_d(a0, current_input_offset(),
           Operand(-char_size() + cp_offset * char_size()));
  BranchOrBacktrack(on_at_start, eq, a0, Operand(a1));
}
 
void RegExpMacroAssemblerLOONG64::CheckNotAtStart(int cp_offset,
                                                  Label* on_not_at_start) {
  __ Ld_d(a1, MemOperand(frame_pointer(), kStringStartMinusOneOffset));
  __ Add_d(a0, current_input_offset(),
           Operand(-char_size() + cp_offset * char_size()));
  BranchOrBacktrack(on_not_at_start, ne, a0, Operand(a1));
}
 
void RegExpMacroAssemblerLOONG64::CheckCharacterLT(base::uc16 limit,
                                                   Label* on_less) {
  BranchOrBacktrack(on_less, lt, current_character(), Operand(limit));
}
 
void RegExpMacroAssemblerLOONG64::CheckGreedyLoop(Label* on_equal) {
  Label backtrack_non_equal;
  __ Ld_w(a0, MemOperand(backtrack_stackpointer(), 0));
  __ Branch(&backtrack_non_equal, ne, current_input_offset(), Operand(a0));
  __ Add_d(backtrack_stackpointer(), backtrack_stackpointer(),
           Operand(kIntSize));
  __ bind(&backtrack_non_equal);
  BranchOrBacktrack(on_equal, eq, current_input_offset(), Operand(a0));
}
 
void RegExpMacroAssemblerLOONG64::CheckNotBackReferenceIgnoreCase(
    int start_reg, bool read_backward, bool unicode, Label* on_no_match) {
  Label fallthrough;
  __ Ld_d(a0, register_location(start_reg));      // Index of start of capture.
  __ Ld_d(a1, register_location(start_reg + 1));  // Index of end of capture.
  __ Sub_d(a1, a1, a0);                           // 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.
  __ Branch(&fallthrough, eq, a1, Operand(zero_reg));
 
  if (read_backward) {
    __ Ld_d(t1, MemOperand(frame_pointer(), kStringStartMinusOneOffset));
    __ Add_d(t1, t1, a1);
    BranchOrBacktrack(on_no_match, le, current_input_offset(), Operand(t1));
  } else {
    __ Add_d(t1, a1, current_input_offset());
    // Check that there are enough characters left in the input.
    BranchOrBacktrack(on_no_match, gt, t1, Operand(zero_reg));
  }
 
  if (mode_ == LATIN1) {
    Label success;
    Label fail;
    Label loop_check;
 
    // a0 - offset of start of capture.
    // a1 - length of capture.
    __ Add_d(a0, a0, Operand(end_of_input_address()));
    __ Add_d(a2, end_of_input_address(), Operand(current_input_offset()));
    if (read_backward) {
      __ Sub_d(a2, a2, Operand(a1));
    }
    __ Add_d(a1, a0, Operand(a1));
 
    // a0 - Address of start of capture.
    // a1 - Address of end of capture.
    // a2 - Address of current input position.
 
    Label loop;
    __ bind(&loop);
    __ Ld_bu(a3, MemOperand(a0, 0));
    __ addi_d(a0, a0, char_size());
    __ Ld_bu(a4, MemOperand(a2, 0));
    __ addi_d(a2, a2, char_size());
 
    __ Branch(&loop_check, eq, a4, Operand(a3));
 
    // Mismatch, try case-insensitive match (converting letters to lower-case).
    __ Or(a3, a3, Operand(0x20));  // Convert capture character to lower-case.
    __ Or(a4, a4, Operand(0x20));  // Also convert input character.
    __ Branch(&fail, ne, a4, Operand(a3));
    __ Sub_d(a3, a3, Operand('a'));
    __ Branch(&loop_check, ls, a3, Operand('z' - 'a'));
    // Latin-1: Check for values in range [224,254] but not 247.
    __ Sub_d(a3, a3, Operand(224 - 'a'));
    // Weren't Latin-1 letters.
    __ Branch(&fail, hi, a3, Operand(254 - 224));
    // Check for 247.
    __ Branch(&fail, eq, a3, Operand(247 - 224));
 
    __ bind(&loop_check);
    __ Branch(&loop, lt, a0, Operand(a1));
    __ jmp(&success);
 
    __ bind(&fail);
    GoTo(on_no_match);
 
    __ bind(&success);
    // Compute new value of character position after the matched part.
    __ Sub_d(current_input_offset(), a2, end_of_input_address());
    if (read_backward) {
      __ Ld_d(t1, register_location(start_reg));  // Index of start of capture.
      __ Ld_d(a2,
              register_location(start_reg + 1));  // Index of end of capture.
      __ Add_d(current_input_offset(), current_input_offset(), Operand(t1));
      __ Sub_d(current_input_offset(), current_input_offset(), Operand(a2));
    }
  } else {
    DCHECK(mode_ == UC16);
 
    int argument_count = 4;
    __ PrepareCallCFunction(argument_count, a2);
 
    // a0 - offset of start of capture.
    // a1 - length of capture.
 
    // Put arguments into arguments registers.
    // Parameters are
    //   a0: Address byte_offset1 - Address captured substring's start.
    //   a1: Address byte_offset2 - Address of current character position.
    //   a2: size_t byte_length - length of capture in bytes(!).
    //   a3: Isolate* isolate.
 
    // Address of start of capture.
    __ Add_d(a0, a0, Operand(end_of_input_address()));
    // Length of capture.
    __ mov(a2, a1);
    // Save length in callee-save register for use on return.
    __ mov(s3, a1);
    // Address of current input position.
    __ Add_d(a1, current_input_offset(), Operand(end_of_input_address()));
    if (read_backward) {
      __ Sub_d(a1, a1, Operand(s3));
    }
    // Isolate.
    __ li(a3, Operand(ExternalReference::isolate_address(masm_->isolate())));
 
    {
      AllowExternalCallThatCantCauseGC scope(masm_.get());
      ExternalReference function =
          unicode
              ? ExternalReference::re_case_insensitive_compare_unicode()
              : ExternalReference::re_case_insensitive_compare_non_unicode();
      CallCFunctionFromIrregexpCode(function, argument_count);
    }
 
    // Check if function returned non-zero for success or zero for failure.
    BranchOrBacktrack(on_no_match, eq, a0, Operand(zero_reg));
    // On success, increment position by length of capture.
    if (read_backward) {
      __ Sub_d(current_input_offset(), current_input_offset(), Operand(s3));
    } else {
      __ Add_d(current_input_offset(), current_input_offset(), Operand(s3));
    }
  }
 
  __ bind(&fallthrough);
}
 
void RegExpMacroAssemblerLOONG64::CheckNotBackReference(int start_reg,
                                                        bool read_backward,
                                                        Label* on_no_match) {
  Label fallthrough;
 
  // Find length of back-referenced capture.
  __ Ld_d(a0, register_location(start_reg));
  __ Ld_d(a1, register_location(start_reg + 1));
  __ Sub_d(a1, a1, a0);  // 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.
  __ Branch(&fallthrough, eq, a1, Operand(zero_reg));
 
  if (read_backward) {
    __ Ld_d(t1, MemOperand(frame_pointer(), kStringStartMinusOneOffset));
    __ Add_d(t1, t1, a1);
    BranchOrBacktrack(on_no_match, le, current_input_offset(), Operand(t1));
  } else {
    __ Add_d(t1, a1, current_input_offset());
    // Check that there are enough characters left in the input.
    BranchOrBacktrack(on_no_match, gt, t1, Operand(zero_reg));
  }
 
  // Compute pointers to match string and capture string.
  __ Add_d(a0, a0, Operand(end_of_input_address()));
  __ Add_d(a2, end_of_input_address(), Operand(current_input_offset()));
  if (read_backward) {
    __ Sub_d(a2, a2, Operand(a1));
  }
  __ Add_d(a1, a1, Operand(a0));
 
  Label loop;
  __ bind(&loop);
  if (mode_ == LATIN1) {
    __ Ld_bu(a3, MemOperand(a0, 0));
    __ addi_d(a0, a0, char_size());
    __ Ld_bu(a4, MemOperand(a2, 0));
    __ addi_d(a2, a2, char_size());
  } else {
    DCHECK(mode_ == UC16);
    __ Ld_hu(a3, MemOperand(a0, 0));
    __ addi_d(a0, a0, char_size());
    __ Ld_hu(a4, MemOperand(a2, 0));
    __ addi_d(a2, a2, char_size());
  }
  BranchOrBacktrack(on_no_match, ne, a3, Operand(a4));
  __ Branch(&loop, lt, a0, Operand(a1));
 
  // Move current character position to position after match.
  __ Sub_d(current_input_offset(), a2, end_of_input_address());
  if (read_backward) {
    __ Ld_d(t1, register_location(start_reg));  // Index of start of capture.
    __ Ld_d(a2, register_location(start_reg + 1));  // Index of end of capture.
    __ Add_d(current_input_offset(), current_input_offset(), Operand(t1));
    __ Sub_d(current_input_offset(), current_input_offset(), Operand(a2));
  }
  __ bind(&fallthrough);
}
 
void RegExpMacroAssemblerLOONG64::CheckNotCharacter(uint32_t c,
                                                    Label* on_not_equal) {
  BranchOrBacktrack(on_not_equal, ne, current_character(), Operand(c));
}
 
void RegExpMacroAssemblerLOONG64::CheckCharacterAfterAnd(uint32_t c,
                                                         uint32_t mask,
                                                         Label* on_equal) {
  __ And(a0, current_character(), Operand(mask));
  Operand rhs = (c == 0) ? Operand(zero_reg) : Operand(c);
  BranchOrBacktrack(on_equal, eq, a0, rhs);
}
 
void RegExpMacroAssemblerLOONG64::CheckNotCharacterAfterAnd(
    uint32_t c, uint32_t mask, Label* on_not_equal) {
  __ And(a0, current_character(), Operand(mask));
  Operand rhs = (c == 0) ? Operand(zero_reg) : Operand(c);
  BranchOrBacktrack(on_not_equal, ne, a0, rhs);
}
 
void RegExpMacroAssemblerLOONG64::CheckNotCharacterAfterMinusAnd(
    base::uc16 c, base::uc16 minus, base::uc16 mask, Label* on_not_equal) {
  DCHECK_GT(String::kMaxUtf16CodeUnit, minus);
  __ Sub_d(a0, current_character(), Operand(minus));
  __ And(a0, a0, Operand(mask));
  BranchOrBacktrack(on_not_equal, ne, a0, Operand(c));
}
 
void RegExpMacroAssemblerLOONG64::CheckCharacterInRange(base::uc16 from,
                                                        base::uc16 to,
                                                        Label* on_in_range) {
  __ Sub_d(a0, current_character(), Operand(from));
  // Unsigned lower-or-same condition.
  BranchOrBacktrack(on_in_range, ls, a0, Operand(to - from));
}
 
void RegExpMacroAssemblerLOONG64::CheckCharacterNotInRange(
    base::uc16 from, base::uc16 to, Label* on_not_in_range) {
  __ Sub_d(a0, current_character(), Operand(from));
  // Unsigned higher condition.
  BranchOrBacktrack(on_not_in_range, hi, a0, Operand(to - from));
}
 
void RegExpMacroAssemblerLOONG64::CallIsCharacterInRangeArray(
    const ZoneList<CharacterRange>* ranges) {
  static const int kNumArguments = 3;
  __ PrepareCallCFunction(kNumArguments, a0);
 
  __ mov(a0, current_character());
  __ li(a1, Operand(GetOrAddRangeArray(ranges)));
  __ li(a2, Operand(ExternalReference::isolate_address(isolate())));
 
  {
    // 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);
  }
 
  __ li(code_pointer(), Operand(masm_->CodeObject()));
}
 
bool RegExpMacroAssemblerLOONG64::CheckCharacterInRangeArray(
    const ZoneList<CharacterRange>* ranges, Label* on_in_range) {
  CallIsCharacterInRangeArray(ranges);
  BranchOrBacktrack(on_in_range, ne, a0, Operand(zero_reg));
  return true;
}
 
bool RegExpMacroAssemblerLOONG64::CheckCharacterNotInRangeArray(
    const ZoneList<CharacterRange>* ranges, Label* on_not_in_range) {
  CallIsCharacterInRangeArray(ranges);
  BranchOrBacktrack(on_not_in_range, eq, a0, Operand(zero_reg));
  return true;
}
 
void RegExpMacroAssemblerLOONG64::CheckBitInTable(Handle<ByteArray> table,
                                                  Label* on_bit_set) {
  __ li(a0, Operand(table));
  if (mode_ != LATIN1 || kTableMask != String::kMaxOneByteCharCode) {
    __ And(a1, current_character(), Operand(kTableSize - 1));
    __ Add_d(a0, a0, a1);
  } else {
    __ Add_d(a0, a0, current_character());
  }
 
  __ Ld_bu(a0, FieldMemOperand(a0, OFFSET_OF_DATA_START(ByteArray)));
  BranchOrBacktrack(on_bit_set, ne, a0, Operand(zero_reg));
}
 
void RegExpMacroAssemblerLOONG64::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 RegExpMacroAssemblerLOONG64::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;
        __ Branch(&success, eq, current_character(), Operand(' '));
        // Check range 0x09..0x0D.
        __ Sub_d(a0, current_character(), Operand('\t'));
        __ Branch(&success, ls, a0, Operand('\r' - '\t'));
        // \u00a0 (NBSP).
        BranchOrBacktrack(on_no_match, ne, a0, Operand(0x00A0 - '\t'));
        __ 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 Latin1 digits ('0'..'9').
      __ Sub_d(a0, current_character(), Operand('0'));
      BranchOrBacktrack(on_no_match, hi, a0, Operand('9' - '0'));
      return true;
    case StandardCharacterSet::kNotDigit:
      // Match non Latin1-digits.
      __ Sub_d(a0, current_character(), Operand('0'));
      BranchOrBacktrack(on_no_match, ls, a0, Operand('9' - '0'));
      return true;
    case StandardCharacterSet::kNotLineTerminator: {
      // Match non-newlines (not 0x0A('\n'), 0x0D('\r'), 0x2028 and 0x2029).
      __ Xor(a0, current_character(), Operand(0x01));
      // See if current character is '\n'^1 or '\r'^1, i.e., 0x0B or 0x0C.
      __ Sub_d(a0, a0, Operand(0x0B));
      BranchOrBacktrack(on_no_match, ls, a0, Operand(0x0C - 0x0B));
      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_d(a0, a0, Operand(0x2028 - 0x0B));
        BranchOrBacktrack(on_no_match, ls, a0, Operand(1));
      }
      return true;
    }
    case StandardCharacterSet::kLineTerminator: {
      // Match newlines (0x0A('\n'), 0x0D('\r'), 0x2028 and 0x2029).
      __ Xor(a0, current_character(), Operand(0x01));
      // See if current character is '\n'^1 or '\r'^1, i.e., 0x0B or 0x0C.
      __ Sub_d(a0, a0, Operand(0x0B));
      if (mode_ == LATIN1) {
        BranchOrBacktrack(on_no_match, hi, a0, Operand(0x0C - 0x0B));
      } else {
        Label done;
        BranchOrBacktrack(&done, ls, a0, Operand(0x0C - 0x0B));
        // 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_d(a0, a0, Operand(0x2028 - 0x0B));
        BranchOrBacktrack(on_no_match, hi, a0, Operand(1));
        __ bind(&done);
      }
      return true;
    }
    case StandardCharacterSet::kWord: {
      if (mode_ != LATIN1) {
        // Table is 256 entries, so all Latin1 characters can be tested.
        BranchOrBacktrack(on_no_match, hi, current_character(), Operand('z'));
      }
      ExternalReference map = ExternalReference::re_word_character_map();
      __ li(a0, Operand(map));
      __ Add_d(a0, a0, current_character());
      __ Ld_bu(a0, MemOperand(a0, 0));
      BranchOrBacktrack(on_no_match, eq, a0, Operand(zero_reg));
      return true;
    }
    case StandardCharacterSet::kNotWord: {
      Label done;
      if (mode_ != LATIN1) {
        // Table is 256 entries, so all Latin1 characters can be tested.
        __ Branch(&done, hi, current_character(), Operand('z'));
      }
      ExternalReference map = ExternalReference::re_word_character_map();
      __ li(a0, Operand(map));
      __ Add_d(a0, a0, current_character());
      __ Ld_bu(a0, MemOperand(a0, 0));
      BranchOrBacktrack(on_no_match, ne, a0, Operand(zero_reg));
      if (mode_ != LATIN1) {
        __ bind(&done);
      }
      return true;
    }
    case StandardCharacterSet::kEverything:
      // Match any character.
      return true;
  }
}
 
void RegExpMacroAssemblerLOONG64::Fail() {
  __ li(a0, Operand(FAILURE));
  __ jmp(&exit_label_);
}
 
void RegExpMacroAssemblerLOONG64::LoadRegExpStackPointerFromMemory(
    Register dst) {
  ExternalReference ref =
      ExternalReference::address_of_regexp_stack_stack_pointer(isolate());
  __ li(dst, ref);
  __ Ld_d(dst, MemOperand(dst, 0));
}
 
void RegExpMacroAssemblerLOONG64::StoreRegExpStackPointerToMemory(
    Register src, Register scratch) {
  ExternalReference ref =
      ExternalReference::address_of_regexp_stack_stack_pointer(isolate());
  __ li(scratch, ref);
  __ St_d(src, MemOperand(scratch, 0));
}
 
void RegExpMacroAssemblerLOONG64::PushRegExpBasePointer(Register stack_pointer,
                                                        Register scratch) {
  ExternalReference ref =
      ExternalReference::address_of_regexp_stack_memory_top_address(isolate());
  __ li(scratch, ref);
  __ Ld_d(scratch, MemOperand(scratch, 0));
  __ Sub_d(scratch, stack_pointer, scratch);
  __ St_d(scratch, MemOperand(frame_pointer(), kRegExpStackBasePointerOffset));
}
 
void RegExpMacroAssemblerLOONG64::PopRegExpBasePointer(
    Register stack_pointer_out, Register scratch) {
  ExternalReference ref =
      ExternalReference::address_of_regexp_stack_memory_top_address(isolate());
  __ Ld_d(stack_pointer_out,
          MemOperand(frame_pointer(), kRegExpStackBasePointerOffset));
  __ li(scratch, ref);
  __ Ld_d(scratch, MemOperand(scratch, 0));
  __ Add_d(stack_pointer_out, stack_pointer_out, scratch);
  StoreRegExpStackPointerToMemory(stack_pointer_out, scratch);
}
 
DirectHandle<HeapObject> RegExpMacroAssemblerLOONG64::GetCode(
    DirectHandle<String> source, RegExpFlags flags) {
  Label return_v0;
  if (0 /* todo masm_->has_exception()*/) {
    // If the code gets corrupted due to long regular expressions and lack of
    // space on trampolines, an internal exception flag is set. If this case
    // is detected, we will jump into exit sequence right away.
    //__ bind_to(&entry_label_, internal_failure_label_.pos());
  } else {
    // 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_.get(), StackFrame::MANUAL);
 
    // Emit code to start a new stack frame. In the following we push all
    // callee-save registers (these end up above the fp) and all register
    // arguments (in {a0,a1,a2,a3}, these end up below the fp).
    // TODO(plind): we save s0..s7, but ONLY use s3 here - use the regs
    // or dont save.
    RegList registers_to_retain = {s0, s1, s2, s3, s4, s5, s6, s7};
 
    __ MultiPush({ra}, {fp}, registers_to_retain);
    __ mov(frame_pointer(), sp);
 
    // Registers {a0,a1,a2,a3} are the first four arguments as per the C calling
    // convention, and must match our specified offsets (e.g. kInputEndOffset).
    //
    // a0: input_string
    // a1: start_offset
    // a2: input_start
    // a3: input_end
    RegList argument_registers = {a0, a1, a2, a3};
    argument_registers |= {a4, a5, a6, a7};
 
    // Also push the frame marker.
    __ li(kScratchReg, Operand(StackFrame::TypeToMarker(StackFrame::IRREGEXP)));
    static_assert(kFrameTypeOffset == kFramePointerOffset - kSystemPointerSize);
    static_assert(kInputEndOffset ==
                  kRegisterOutputOffset - kSystemPointerSize);
    static_assert(kInputStartOffset == kInputEndOffset - kSystemPointerSize);
    static_assert(kStartIndexOffset == kInputStartOffset - kSystemPointerSize);
    static_assert(kInputStringOffset == kStartIndexOffset - kSystemPointerSize);
    __ MultiPush(argument_registers | kScratchReg);
 
    static_assert(kSuccessfulCapturesOffset ==
                  kInputStringOffset - kSystemPointerSize);
    __ mov(a0, zero_reg);
    __ Push(a0);  // Make room for success counter and initialize it to 0.
    static_assert(kStringStartMinusOneOffset ==
                  kSuccessfulCapturesOffset - kSystemPointerSize);
    __ Push(a0);  // Make room for "string start - 1" constant.
    static_assert(kBacktrackCountOffset ==
                  kStringStartMinusOneOffset - kSystemPointerSize);
    __ Push(a0);  // The backtrack counter
    static_assert(kRegExpStackBasePointerOffset ==
                  kBacktrackCountOffset - kSystemPointerSize);
    __ Push(a0);  // The regexp stack base ptr.
 
    // Initialize backtrack stack pointer. It must not be clobbered from here
    // on. Note the backtrack_stackpointer is callee-saved.
    static_assert(backtrack_stackpointer() == s7);
    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(), a1);
 
    {
      // Check if we have space on the stack for registers.
      Label stack_limit_hit, stack_ok;
 
      ExternalReference stack_limit =
          ExternalReference::address_of_jslimit(masm_->isolate());
      Operand extra_space_for_variables(num_registers_ * kSystemPointerSize);
 
      __ li(a0, Operand(stack_limit));
      __ Ld_d(a0, MemOperand(a0, 0));
      __ Sub_d(a0, sp, a0);
      // Handle it if the stack pointer is already below the stack limit.
      __ Branch(&stack_limit_hit, le, a0, Operand(zero_reg));
      // Check if there is room for the variable number of registers above
      // the stack limit.
      __ Branch(&stack_ok, hs, a0, extra_space_for_variables);
      // Exit with OutOfMemory exception. There is not enough space on the stack
      // for our working registers.
      __ li(a0, Operand(EXCEPTION));
      __ jmp(&return_v0);
 
      __ bind(&stack_limit_hit);
      CallCheckStackGuardState(a0, extra_space_for_variables);
      // If returned value is non-zero, we exit with the returned value as
      // result.
      __ Branch(&return_v0, ne, a0, Operand(zero_reg));
 
      __ bind(&stack_ok);
    }
 
    // Allocate space on stack for registers.
    __ Sub_d(sp, sp, Operand(num_registers_ * kSystemPointerSize));
    // Load string end.
    __ Ld_d(end_of_input_address(),
            MemOperand(frame_pointer(), kInputEndOffset));
    // Load input start.
    __ Ld_d(a0, MemOperand(frame_pointer(), kInputStartOffset));
    // Find negative length (offset of start relative to end).
    __ Sub_d(current_input_offset(), a0, end_of_input_address());
    // Set a0 to address of char before start of the input string
    // (effectively string position -1).
    __ Ld_d(a1, MemOperand(frame_pointer(), kStartIndexOffset));
    __ Sub_d(a0, current_input_offset(), Operand(char_size()));
    __ slli_d(t1, a1, (mode_ == UC16) ? 1 : 0);
    __ Sub_d(a0, a0, t1);
    // Store this value in a local variable, for use when clearing
    // position registers.
    __ St_d(a0, MemOperand(frame_pointer(), kStringStartMinusOneOffset));
 
    // Initialize code pointer register
    __ li(code_pointer(), Operand(masm_->CodeObject()), CONSTANT_SIZE);
 
    Label load_char_start_regexp;
    {
      Label start_regexp;
      // Load newline if index is at start, previous character otherwise.
      __ Branch(&load_char_start_regexp, ne, a1, Operand(zero_reg));
      __ li(current_character(), Operand('\n'));
      __ jmp(&start_regexp);
 
      // 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.
      if (num_saved_registers_ > 8) {
        // Address of register 0.
        __ Add_d(a1, frame_pointer(), Operand(kRegisterZeroOffset));
        __ li(a2, Operand(num_saved_registers_));
        Label init_loop;
        __ bind(&init_loop);
        __ St_d(a0, MemOperand(a1, 0));
        __ Add_d(a1, a1, Operand(-kSystemPointerSize));
        __ Sub_d(a2, a2, Operand(1));
        __ Branch(&init_loop, ne, a2, Operand(zero_reg));
      } else {
        for (int i = 0; i < num_saved_registers_; i++) {
          __ St_d(a0, register_location(i));
        }
      }
    }
 
    __ 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.
        __ Ld_d(a1, MemOperand(frame_pointer(), kInputStartOffset));
        __ Ld_d(a0, MemOperand(frame_pointer(), kRegisterOutputOffset));
        __ Ld_d(a2, MemOperand(frame_pointer(), kStartIndexOffset));
        __ Sub_d(a1, end_of_input_address(), a1);
        // a1 is length of input in bytes.
        if (mode_ == UC16) {
          __ srli_d(a1, a1, 1);
        }
        // a1 is length of input in characters.
        __ Add_d(a1, a1, Operand(a2));
        // a1 is length of string in characters.
 
        DCHECK_EQ(0, num_saved_registers_ % 2);
        // Always an even number of capture registers. This allows us to
        // unroll the loop once to add an operation between a load of a register
        // and the following use of that register.
        for (int i = 0; i < num_saved_registers_; i += 2) {
          __ Ld_d(a2, register_location(i));
          __ Ld_d(a3, register_location(i + 1));
          if (i == 0 && global_with_zero_length_check()) {
            // Keep capture start in a4 for the zero-length check later.
            __ mov(t3, a2);
          }
          if (mode_ == UC16) {
            __ srai_d(a2, a2, 1);
            __ Add_d(a2, a2, a1);
            __ srai_d(a3, a3, 1);
            __ Add_d(a3, a3, a1);
          } else {
            __ Add_d(a2, a1, Operand(a2));
            __ Add_d(a3, a1, Operand(a3));
          }
          // V8 expects the output to be an int32_t array.
          __ St_w(a2, MemOperand(a0, 0));
          __ Add_d(a0, a0, kIntSize);
          __ St_w(a3, MemOperand(a0, 0));
          __ Add_d(a0, a0, kIntSize);
        }
      }
 
      if (global()) {
        // Restart matching if the regular expression is flagged as global.
        __ Ld_d(a0, MemOperand(frame_pointer(), kSuccessfulCapturesOffset));
        __ Ld_d(a1, MemOperand(frame_pointer(), kNumOutputRegistersOffset));
        __ Ld_d(a2, MemOperand(frame_pointer(), kRegisterOutputOffset));
        // Increment success counter.
        __ Add_d(a0, a0, 1);
        __ St_d(a0, MemOperand(frame_pointer(), kSuccessfulCapturesOffset));
        // Capture results have been stored, so the number of remaining global
        // output registers is reduced by the number of stored captures.
        __ Sub_d(a1, a1, num_saved_registers_);
        // Check whether we have enough room for another set of capture results.
        //__ mov(v0, a0);
        __ Branch(&return_v0, lt, a1, Operand(num_saved_registers_));
 
        __ St_d(a1, MemOperand(frame_pointer(), kNumOutputRegistersOffset));
        // Advance the location for output.
        __ Add_d(a2, a2, num_saved_registers_ * kIntSize);
        __ St_d(a2, MemOperand(frame_pointer(), kRegisterOutputOffset));
 
        // Restore the original regexp stack pointer value (effectively, pop the
        // stored base pointer).
        PopRegExpBasePointer(backtrack_stackpointer(), a2);
 
        Label reload_string_start_minus_one;
 
        if (global_with_zero_length_check()) {
          // Special case for zero-length matches.
          // t3: capture start index
          // Not a zero-length match, restart.
          __ Branch(&reload_string_start_minus_one, ne, current_input_offset(),
                    Operand(t3));
          // Offset from the end is zero if we already reached the end.
          __ Branch(&exit_label_, eq, current_input_offset(),
                    Operand(zero_reg));
          // Advance current position after a zero-length match.
          Label advance;
          __ bind(&advance);
          __ Add_d(current_input_offset(), current_input_offset(),
                   Operand((mode_ == UC16) ? 2 : 1));
          if (global_unicode()) CheckNotInSurrogatePair(0, &advance);
        }
 
        __ bind(&reload_string_start_minus_one);
        // Prepare a0 to initialize registers with its value in the next run.
        // Must be immediately before the jump to avoid clobbering.
        __ Ld_d(a0, MemOperand(frame_pointer(), kStringStartMinusOneOffset));
 
        __ Branch(&load_char_start_regexp);
      } else {
        __ li(a0, Operand(SUCCESS));
      }
    }
    // Exit and return v0.
    __ bind(&exit_label_);
    if (global()) {
      __ Ld_d(a0, MemOperand(frame_pointer(), kSuccessfulCapturesOffset));
    }
 
    __ bind(&return_v0);
    // Restore the original regexp stack pointer value (effectively, pop the
    // stored base pointer).
    PopRegExpBasePointer(backtrack_stackpointer(), a2);
 
    // Skip sp past regexp registers and local variables..
    __ mov(sp, frame_pointer());
    // Restore registers s0..s7 and return (restoring ra to pc).
    __ MultiPop({ra}, {fp}, registers_to_retain);
    __ Ret();
 
    // 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_);
      // Put regexp engine registers on stack.
      StoreRegExpStackPointerToMemory(backtrack_stackpointer(), a1);
 
      CallCheckStackGuardState(a0);
      // If returning non-zero, we should end execution with the given
      // result as return value.
      __ Branch(&return_v0, ne, a0, Operand(zero_reg));
 
      LoadRegExpStackPointerFromMemory(backtrack_stackpointer());
 
      // String might have moved: Reload end of string from frame.
      __ Ld_d(end_of_input_address(),
              MemOperand(frame_pointer(), kInputEndOffset));
 
      SafeReturn();
    }
 
    // Backtrack stack overflow code.
    if (stack_overflow_label_.is_linked()) {
      SafeCallTarget(&stack_overflow_label_);
      StoreRegExpStackPointerToMemory(backtrack_stackpointer(), a1);
      // Reached if the backtrack-stack limit has been hit.
 
      // Call GrowStack(isolate).
      static const int kNumArguments = 1;
      __ PrepareCallCFunction(kNumArguments, a0);
      __ li(a0, Operand(ExternalReference::isolate_address(masm_->isolate())));
      ExternalReference grow_stack = ExternalReference::re_grow_stack();
      CallCFunctionFromIrregexpCode(grow_stack, kNumArguments);
      // If nullptr is returned, we have failed to grow the stack, and must exit
      // with a stack-overflow exception.
      __ Branch(&exit_with_exception, eq, a0, Operand(zero_reg));
      // Otherwise use return value as new stack pointer.
      __ mov(backtrack_stackpointer(), a0);
      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.
      __ li(a0, Operand(EXCEPTION));
      __ jmp(&return_v0);
    }
 
    if (fallback_label_.is_linked()) {
      __ bind(&fallback_label_);
      __ li(a0, Operand(FALLBACK_TO_EXPERIMENTAL));
      __ jmp(&return_v0);
    }
  }
 
  CodeDesc code_desc;
  masm_->GetCode(isolate(), &code_desc);
  Handle<Code> code =
      Factory::CodeBuilder(isolate(), code_desc, CodeKind::REGEXP)
          .set_self_reference(masm_->CodeObject())
          .set_empty_source_position_table()
          .Build();
  LOG(masm_->isolate(),
      RegExpCodeCreateEvent(Cast<AbstractCode>(code), source, flags));
  return Cast<HeapObject>(code);
}
 
void RegExpMacroAssemblerLOONG64::GoTo(Label* to) {
  if (to == nullptr) {
    Backtrack();
    return;
  }
  __ jmp(to);
  return;
}
 
void RegExpMacroAssemblerLOONG64::IfRegisterGE(int reg, int comparand,
                                               Label* if_ge) {
  __ Ld_d(a0, register_location(reg));
  BranchOrBacktrack(if_ge, ge, a0, Operand(comparand));
}
 
void RegExpMacroAssemblerLOONG64::IfRegisterLT(int reg, int comparand,
                                               Label* if_lt) {
  __ Ld_d(a0, register_location(reg));
  BranchOrBacktrack(if_lt, lt, a0, Operand(comparand));
}
 
void RegExpMacroAssemblerLOONG64::IfRegisterEqPos(int reg, Label* if_eq) {
  __ Ld_d(a0, register_location(reg));
  BranchOrBacktrack(if_eq, eq, a0, Operand(current_input_offset()));
}
 
RegExpMacroAssembler::IrregexpImplementation
RegExpMacroAssemblerLOONG64::Implementation() {
  return kLOONG64Implementation;
}
 
void RegExpMacroAssemblerLOONG64::PopCurrentPosition() {
  Pop(current_input_offset());
}
 
void RegExpMacroAssemblerLOONG64::PopRegister(int register_index) {
  Pop(a0);
  __ St_d(a0, register_location(register_index));
}
 
void RegExpMacroAssemblerLOONG64::PushBacktrack(Label* label) {
  if (label->is_bound()) {
    int target = label->pos();
    __ li(a0,
          Operand(target + InstructionStream::kHeaderSize - kHeapObjectTag));
  } else {
    Assembler::BlockTrampolinePoolScope block_trampoline_pool(masm_.get());
    Label after_constant;
    __ Branch(&after_constant);
    int offset = masm_->pc_offset();
    int cp_offset = offset + InstructionStream::kHeaderSize - kHeapObjectTag;
    //__ emit(0);
    __ nop();
    masm_->label_at_put(label, offset);
    __ bind(&after_constant);
    if (is_int12(cp_offset)) {
      __ Ld_wu(a0, MemOperand(code_pointer(), cp_offset));
    } else {
      __ Add_d(a0, code_pointer(), cp_offset);
      __ Ld_wu(a0, MemOperand(a0, 0));
    }
  }
  Push(a0);
  CheckStackLimit();
}
 
void RegExpMacroAssemblerLOONG64::PushCurrentPosition() {
  Push(current_input_offset());
  CheckStackLimit();
}
 
void RegExpMacroAssemblerLOONG64::PushRegister(
    int register_index, StackCheckFlag check_stack_limit) {
  __ Ld_d(a0, register_location(register_index));
  Push(a0);
  if (check_stack_limit) {
    CheckStackLimit();
  } else if (V8_UNLIKELY(v8_flags.slow_debug_code)) {
    AssertAboveStackLimitMinusSlack();
  }
}
 
void RegExpMacroAssemblerLOONG64::ReadCurrentPositionFromRegister(int reg) {
  __ Ld_d(current_input_offset(), register_location(reg));
}
 
void RegExpMacroAssemblerLOONG64::WriteStackPointerToRegister(int reg) {
  ExternalReference stack_top_address =
      ExternalReference::address_of_regexp_stack_memory_top_address(isolate());
  __ li(a0, stack_top_address);
  __ Ld_d(a0, MemOperand(a0, 0));
  __ Sub_d(a0, backtrack_stackpointer(), a0);
  __ St_d(a0, register_location(reg));
}
 
void RegExpMacroAssemblerLOONG64::ReadStackPointerFromRegister(int reg) {
  ExternalReference stack_top_address =
      ExternalReference::address_of_regexp_stack_memory_top_address(isolate());
  __ li(backtrack_stackpointer(), stack_top_address);
  __ Ld_d(backtrack_stackpointer(), MemOperand(backtrack_stackpointer(), 0));
  __ Ld_d(a0, register_location(reg));
  __ Add_d(backtrack_stackpointer(), backtrack_stackpointer(), Operand(a0));
}
 
void RegExpMacroAssemblerLOONG64::SetCurrentPositionFromEnd(int by) {
  Label after_position;
  __ Branch(&after_position, ge, current_input_offset(),
            Operand(-by * char_size()));
  __ li(current_input_offset(), -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 RegExpMacroAssemblerLOONG64::SetRegister(int register_index, int to) {
  DCHECK(register_index >= num_saved_registers_);  // Reserved for positions!
  __ li(a0, Operand(to));
  __ St_d(a0, register_location(register_index));
}
 
bool RegExpMacroAssemblerLOONG64::Succeed() {
  __ jmp(&success_label_);
  return global();
}
 
void RegExpMacroAssemblerLOONG64::WriteCurrentPositionToRegister(
    int reg, int cp_offset) {
  if (cp_offset == 0) {
    __ St_d(current_input_offset(), register_location(reg));
  } else {
    __ Add_d(a0, current_input_offset(), Operand(cp_offset * char_size()));
    __ St_d(a0, register_location(reg));
  }
}
 
void RegExpMacroAssemblerLOONG64::ClearRegisters(int reg_from, int reg_to) {
  DCHECK(reg_from <= reg_to);
  __ Ld_d(a0, MemOperand(frame_pointer(), kStringStartMinusOneOffset));
  for (int reg = reg_from; reg <= reg_to; reg++) {
    __ St_d(a0, register_location(reg));
  }
}
 
// Private methods:
 
void RegExpMacroAssemblerLOONG64::CallCheckStackGuardState(
    Register scratch, Operand extra_space) {
  DCHECK(!isolate()->IsGeneratingEmbeddedBuiltins());
  DCHECK(!masm_->options().isolate_independent_code);
 
  int stack_alignment = base::OS::ActivationFrameAlignment();
 
  // Align the stack pointer and save the original sp value on the stack.
  __ mov(scratch, sp);
  __ Sub_d(sp, sp, Operand(kSystemPointerSize));
  DCHECK(base::bits::IsPowerOfTwo(stack_alignment));
  __ And(sp, sp, Operand(-stack_alignment));
  __ St_d(scratch, MemOperand(sp, 0));
 
  // Extra space for variables.
  __ li(a3, extra_space);
  // RegExp code frame pointer.
  __ mov(a2, frame_pointer());
  // InstructionStream of self.
  __ li(a1, Operand(masm_->CodeObject()), CONSTANT_SIZE);
 
  // We need to make room for the return address on the stack.
  DCHECK(IsAligned(stack_alignment, kSystemPointerSize));
  __ Sub_d(sp, sp, Operand(stack_alignment));
 
  // a0 will point to the return address, placed by DirectCEntry.
  __ mov(a0, sp);
 
  ExternalReference stack_guard_check =
      ExternalReference::re_check_stack_guard_state();
  __ li(t5, Operand(stack_guard_check));
 
  EmbeddedData d = EmbeddedData::FromBlob();
  CHECK(Builtins::IsIsolateIndependent(Builtin::kDirectCEntry));
  Address entry = d.InstructionStartOf(Builtin::kDirectCEntry);
  __ li(kScratchReg, Operand(entry, RelocInfo::OFF_HEAP_TARGET));
  __ Call(kScratchReg);
 
  __ Ld_d(sp, MemOperand(sp, stack_alignment));
 
  __ li(code_pointer(), Operand(masm_->CodeObject()));
}
 
// 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);
}
 
int64_t RegExpMacroAssemblerLOONG64::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),
      static_cast<int>(frame_entry<int64_t>(re_frame, kStartIndexOffset)),
      static_cast<RegExp::CallOrigin>(
          frame_entry<int64_t>(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);
}
 
MemOperand RegExpMacroAssemblerLOONG64::register_location(int register_index) {
  DCHECK(register_index < (1 << 30));
  if (num_registers_ <= register_index) {
    num_registers_ = register_index + 1;
  }
  return MemOperand(frame_pointer(),
                    kRegisterZeroOffset - register_index * kSystemPointerSize);
}
 
void RegExpMacroAssemblerLOONG64::CheckPosition(int cp_offset,
                                                Label* on_outside_input) {
  if (cp_offset >= 0) {
    BranchOrBacktrack(on_outside_input, ge, current_input_offset(),
                      Operand(-cp_offset * char_size()));
  } else {
    __ Ld_d(a1, MemOperand(frame_pointer(), kStringStartMinusOneOffset));
    __ Add_d(a0, current_input_offset(), Operand(cp_offset * char_size()));
    BranchOrBacktrack(on_outside_input, le, a0, Operand(a1));
  }
}
 
void RegExpMacroAssemblerLOONG64::BranchOrBacktrack(Label* to,
                                                    Condition condition,
                                                    Register rs,
                                                    const Operand& rt) {
  if (condition == al) {  // Unconditional.
    if (to == nullptr) {
      Backtrack();
      return;
    }
    __ jmp(to);
    return;
  }
  if (to == nullptr) {
    __ Branch(&backtrack_label_, condition, rs, rt);
    return;
  }
  __ Branch(to, condition, rs, rt);
}
 
void RegExpMacroAssemblerLOONG64::SafeCall(Label* to, Condition cond,
                                           Register rs, const Operand& rt) {
  __ Branch(to, cond, rs, rt, true);
}
 
void RegExpMacroAssemblerLOONG64::SafeReturn() {
  __ Pop(ra);
  __ Add_d(t1, ra, Operand(masm_->CodeObject()));
  __ Jump(t1);
}
 
void RegExpMacroAssemblerLOONG64::SafeCallTarget(Label* name) {
  __ bind(name);
  __ Sub_d(ra, ra, Operand(masm_->CodeObject()));
  __ Push(ra);
}
 
void RegExpMacroAssemblerLOONG64::Push(Register source) {
  DCHECK(source != backtrack_stackpointer());
  __ Add_d(backtrack_stackpointer(), backtrack_stackpointer(),
           Operand(-kIntSize));
  __ St_w(source, MemOperand(backtrack_stackpointer(), 0));
}
 
void RegExpMacroAssemblerLOONG64::Pop(Register target) {
  DCHECK(target != backtrack_stackpointer());
  __ Ld_w(target, MemOperand(backtrack_stackpointer(), 0));
  __ Add_d(backtrack_stackpointer(), backtrack_stackpointer(), kIntSize);
}
 
void RegExpMacroAssemblerLOONG64::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 RegExpMacroAssemblerLOONG64::CheckPreemption() {
  // Check for preemption.
  ExternalReference stack_limit =
      ExternalReference::address_of_jslimit(masm_->isolate());
  __ li(a0, Operand(stack_limit));
  __ Ld_d(a0, MemOperand(a0, 0));
  SafeCall(&check_preempt_label_, ls, sp, Operand(a0));
}
 
void RegExpMacroAssemblerLOONG64::CheckStackLimit() {
  ExternalReference stack_limit =
      ExternalReference::address_of_regexp_stack_limit_address(
          masm_->isolate());
 
  __ li(a0, Operand(stack_limit));
  __ Ld_d(a0, MemOperand(a0, 0));
  SafeCall(&stack_overflow_label_, ls, backtrack_stackpointer(), Operand(a0));
}
 
void RegExpMacroAssemblerLOONG64::AssertAboveStackLimitMinusSlack() {
  ExternalReference stack_limit =
      ExternalReference::address_of_regexp_stack_limit_address(
          masm_->isolate());
 
  __ li(a0, Operand(stack_limit));
  __ Ld_d(a0, MemOperand(a0, 0));
  SafeCall(&stack_overflow_label_, ls, backtrack_stackpointer(), Operand(a0));
 
  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());
  __ li(a0, l);
  __ Ld_d(a0, MemOperand(a0, 0));
  __ Sub_d(a0, a0, Operand(RegExpStack::kStackLimitSlackSize));
  __ Branch(&no_stack_overflow, hi, backtrack_stackpointer(), Operand(a0));
  __ DebugBreak();
  __ bind(&no_stack_overflow);
}
 
void RegExpMacroAssemblerLOONG64::LoadCurrentCharacterUnchecked(
    int cp_offset, int characters) {
  Register offset = current_input_offset();
 
  // If unaligned load/stores are not supported then this function must only
  // be used to load a single character at a time.
  if (!CanReadUnaligned()) {
    DCHECK_EQ(1, characters);
  }
 
  if (cp_offset != 0) {
    // t3 is not being used to store the capture start index at this point.
    __ Add_d(t3, current_input_offset(), Operand(cp_offset * char_size()));
    offset = t3;
  }
 
  if (mode_ == LATIN1) {
    if (characters == 4) {
      __ Ld_wu(current_character(), MemOperand(end_of_input_address(), offset));
    } else if (characters == 2) {
      __ Ld_hu(current_character(), MemOperand(end_of_input_address(), offset));
    } else {
      DCHECK_EQ(1, characters);
      __ Ld_bu(current_character(), MemOperand(end_of_input_address(), offset));
    }
  } else {
    DCHECK(mode_ == UC16);
    if (characters == 2) {
      __ Ld_wu(current_character(), MemOperand(end_of_input_address(), offset));
    } else {
      DCHECK_EQ(1, characters);
      __ Ld_hu(current_character(), MemOperand(end_of_input_address(), offset));
    }
  }
}
 
#undef __
 
}  // namespace internal
}  // namespace v8
 
#endif  // V8_TARGET_ARCH_LOONG64