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diff --git a/js/src/irregexp/RegExpNativeMacroAssembler.h b/js/src/irregexp/RegExpNativeMacroAssembler.h
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+++ b/js/src/irregexp/RegExpNativeMacroAssembler.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Copyright 2020 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.
+
+// This file implements the NativeRegExpMacroAssembler interface for
+// SpiderMonkey. It provides the same interface as each of V8's
+// architecture-specific implementations.
+
+#ifndef RegexpMacroAssemblerArch_h
+#define RegexpMacroAssemblerArch_h
+
+#include "irregexp/imported/regexp-macro-assembler.h"
+#include "jit/MacroAssembler.h"
+
+namespace v8 {
+namespace internal {
+
+struct FrameData {
+  // Character position at the start of the input, stored as a
+  // negative offset from the end of the string (input_end_pointer_).
+  size_t inputStart;
+
+  // The backtrack_stack_pointer_ register points to the top of the stack.
+  // This points to the bottom of the backtrack stack.
+  void* backtrackStackBase;
+
+  // Copy of the input MatchPairs.
+  int32_t* matches;    // pointer to capture array
+  int32_t numMatches;  // size of capture array
+};
+
+class SMRegExpMacroAssembler final : public NativeRegExpMacroAssembler {
+ public:
+  SMRegExpMacroAssembler(JSContext* cx, js::jit::StackMacroAssembler& masm,
+                         Zone* zone, Mode mode, uint32_t num_capture_registers);
+  virtual ~SMRegExpMacroAssembler() = default;
+
+  virtual int stack_limit_slack();
+  virtual IrregexpImplementation Implementation();
+
+  virtual bool Succeed();
+  virtual void Fail();
+
+  virtual void AdvanceCurrentPosition(int by);
+  virtual void PopCurrentPosition();
+  virtual void PushCurrentPosition();
+  virtual void SetCurrentPositionFromEnd(int by);
+
+  virtual void Backtrack();
+  virtual void Bind(Label* label);
+  virtual void GoTo(Label* label);
+  virtual void PushBacktrack(Label* label);
+
+  virtual void CheckCharacter(uint32_t c, Label* on_equal);
+  virtual void CheckNotCharacter(uint32_t c, Label* on_not_equal);
+  virtual void CheckCharacterGT(base::uc16 limit, Label* on_greater);
+  virtual void CheckCharacterLT(base::uc16 limit, Label* on_less);
+  virtual void CheckCharacterAfterAnd(uint32_t c, uint32_t mask,
+                                      Label* on_equal);
+  virtual void CheckNotCharacterAfterAnd(uint32_t c, uint32_t mask,
+                                         Label* on_not_equal);
+  virtual void CheckNotCharacterAfterMinusAnd(base::uc16 c, base::uc16 minus,
+                                              base::uc16 mask,
+                                              Label* on_not_equal);
+  virtual void CheckGreedyLoop(Label* on_tos_equals_current_position);
+  virtual void CheckCharacterInRange(base::uc16 from, base::uc16 to,
+                                     Label* on_in_range);
+  virtual void CheckCharacterNotInRange(base::uc16 from, base::uc16 to,
+                                        Label* on_not_in_range);
+  virtual bool CheckCharacterInRangeArray(
+      const ZoneList<CharacterRange>* ranges, Label* on_in_range);
+  virtual bool CheckCharacterNotInRangeArray(
+      const ZoneList<CharacterRange>* ranges, Label* on_not_in_range);
+  virtual void CheckAtStart(int cp_offset, Label* on_at_start);
+  virtual void CheckNotAtStart(int cp_offset, Label* on_not_at_start);
+  virtual void CheckPosition(int cp_offset, Label* on_outside_input);
+  virtual void CheckBitInTable(Handle<ByteArray> table, Label* on_bit_set);
+  virtual bool CheckSpecialCharacterClass(StandardCharacterSet type,
+                                          Label* on_no_match);
+  virtual void CheckNotBackReference(int start_reg, bool read_backward,
+                                     Label* on_no_match);
+  virtual void CheckNotBackReferenceIgnoreCase(int start_reg,
+                                               bool read_backward, bool unicode,
+                                               Label* on_no_match);
+
+  virtual void LoadCurrentCharacterImpl(int cp_offset, Label* on_end_of_input,
+                                        bool check_bounds, int characters,
+                                        int eats_at_least);
+
+  virtual void AdvanceRegister(int reg, int by);
+  virtual void IfRegisterGE(int reg, int comparand, Label* if_ge);
+  virtual void IfRegisterLT(int reg, int comparand, Label* if_lt);
+  virtual void IfRegisterEqPos(int reg, Label* if_eq);
+  virtual void PopRegister(int register_index);
+  virtual void PushRegister(int register_index,
+                            StackCheckFlag check_stack_limit);
+  virtual void ReadCurrentPositionFromRegister(int reg);
+  virtual void WriteCurrentPositionToRegister(int reg, int cp_offset);
+  virtual void ReadStackPointerFromRegister(int reg);
+  virtual void WriteStackPointerToRegister(int reg);
+  virtual void SetRegister(int register_index, int to);
+  virtual void ClearRegisters(int reg_from, int reg_to);
+
+  virtual Handle<HeapObject> GetCode(Handle<String> source);
+
+  virtual bool CanReadUnaligned() const;
+
+ private:
+  size_t frameSize_ = 0;
+
+  void createStackFrame();
+  void initFrameAndRegs();
+  void successHandler();
+  void exitHandler();
+  void backtrackHandler();
+  void stackOverflowHandler();
+
+  // Push a register on the backtrack stack.
+  void Push(js::jit::Register value);
+
+  // Pop a value from the backtrack stack.
+  void Pop(js::jit::Register target);
+
+  void CheckAtStartImpl(int cp_offset, Label* on_cond,
+                        js::jit::Assembler::Condition cond);
+  void CheckCharacterImpl(js::jit::Imm32 c, Label* on_cond,
+                          js::jit::Assembler::Condition cond);
+  void CheckCharacterAfterAndImpl(uint32_t c, uint32_t and_with, Label* on_cond,
+                                  bool negate);
+  void CheckCharacterInRangeImpl(base::uc16 from, base::uc16 to, Label* on_cond,
+                                 js::jit::Assembler::Condition cond);
+  void CheckNotBackReferenceImpl(int start_reg, bool read_backward,
+                                 bool unicode, Label* on_no_match,
+                                 bool ignore_case);
+  void CallIsCharacterInRangeArray(const ZoneList<CharacterRange>* ranges);
+
+  void LoadCurrentCharacterUnchecked(int cp_offset, int characters);
+
+  void JumpOrBacktrack(Label* to);
+
+  // MacroAssembler methods that take a Label can be called with a
+  // null label, which means that we should backtrack if we would jump
+  // to that label. This is a helper to avoid writing out the same
+  // logic a dozen times.
+  inline js::jit::Label* LabelOrBacktrack(Label* to) {
+    return to ? to->inner() : &backtrack_label_;
+  }
+
+  void CheckBacktrackStackLimit();
+
+ public:
+  static bool GrowBacktrackStack(RegExpStack* regexp_stack);
+
+  static uint32_t CaseInsensitiveCompareNonUnicode(const char16_t* substring1,
+                                                   const char16_t* substring2,
+                                                   size_t byteLength);
+  static uint32_t CaseInsensitiveCompareUnicode(const char16_t* substring1,
+                                                const char16_t* substring2,
+                                                size_t byteLength);
+  static bool IsCharacterInRangeArray(uint32_t c, ByteArrayData* ranges);
+
+ private:
+  inline int char_size() { return static_cast<int>(mode_); }
+  inline js::jit::Scale factor() {
+    return mode_ == UC16 ? js::jit::TimesTwo : js::jit::TimesOne;
+  }
+
+  js::jit::Address inputStart() {
+    return js::jit::Address(masm_.getStackPointer(),
+                            offsetof(FrameData, inputStart));
+  }
+  js::jit::Address backtrackStackBase() {
+    return js::jit::Address(masm_.getStackPointer(),
+                            offsetof(FrameData, backtrackStackBase));
+  }
+  js::jit::Address matches() {
+    return js::jit::Address(masm_.getStackPointer(),
+                            offsetof(FrameData, matches));
+  }
+  js::jit::Address numMatches() {
+    return js::jit::Address(masm_.getStackPointer(),
+                            offsetof(FrameData, numMatches));
+  }
+
+  // The stack-pointer-relative location of a regexp register.
+  js::jit::Address register_location(int register_index) {
+    return js::jit::Address(masm_.getStackPointer(),
+                            register_offset(register_index));
+  }
+
+  int32_t register_offset(int register_index) {
+    MOZ_ASSERT(register_index >= 0 && register_index <= kMaxRegister);
+    if (num_registers_ <= register_index) {
+      num_registers_ = register_index + 1;
+    }
+    static_assert(alignof(uintptr_t) <= alignof(FrameData));
+    return sizeof(FrameData) + register_index * sizeof(uintptr_t*);
+  }
+
+  JSContext* cx_;
+  js::jit::StackMacroAssembler& masm_;
+
+  /*
+   * This assembler uses the following registers:
+   *
+   * - current_character_:
+   *     Contains the character (or characters) currently being examined.
+   *     Must be loaded using LoadCurrentCharacter before using any of the
+   *     dispatch methods. After a matching pass for a global regexp,
+   *     temporarily stores the index of capture start.
+   * - current_position_:
+   *     Current position in input *as negative byte offset from end of string*.
+   * - input_end_pointer_:
+   *     Points to byte after last character in the input. current_position_ is
+   *     relative to this.
+   * - backtrack_stack_pointer_:
+   *     Points to tip of the (heap-allocated) backtrack stack. The stack grows
+   *     downward (like the native stack).
+   * - temp0_, temp1_, temp2_:
+   *     Scratch registers.
+   *
+   * The native stack pointer is used to access arguments (InputOutputData),
+   * local variables (FrameData), and irregexp's internal virtual registers
+   * (see register_location).
+   */
+
+  js::jit::Register current_character_;
+  js::jit::Register current_position_;
+  js::jit::Register input_end_pointer_;
+  js::jit::Register backtrack_stack_pointer_;
+  js::jit::Register temp0_, temp1_, temp2_;
+
+  // These labels are used in various API calls and bound (if used) in
+  // GetCode. If we abort in the middle of a compilation, as may
+  // happen if a regexp is too big, they may be used but not
+  // bound.
+  js::jit::NonAssertingLabel entry_label_;
+  js::jit::NonAssertingLabel start_label_;
+  js::jit::NonAssertingLabel backtrack_label_;
+  js::jit::NonAssertingLabel success_label_;
+  js::jit::NonAssertingLabel exit_label_;
+  js::jit::NonAssertingLabel stack_overflow_label_;
+  js::jit::NonAssertingLabel exit_with_exception_label_;
+
+  // When we generate the code to push a backtrack label's address
+  // onto the backtrack stack, we don't know its final address. We
+  // have to patch it after linking. This is slightly delicate, as the
+  // Label itself (which is allocated on the stack) may not exist by
+  // the time we link. The approach is as follows:
+  //
+  // 1. When we push a label on the backtrack stack (PushBacktrack),
+  //    we bind the label's patchOffset_ field to the offset within
+  //    the code that should be overwritten. This works because each
+  //    label is only pushed by a single instruction.
+  //
+  // 2. When we bind a label (Bind), we check to see if it has a
+  //    bound patchOffset_. If it does, we create a LabelPatch mapping
+  //    its patch offset to the offset of the label itself.
+  //
+  // 3. While linking the code, we walk the list of label patches
+  //    and patch the code accordingly.
+  class LabelPatch {
+   public:
+    LabelPatch(js::jit::CodeOffset patchOffset, size_t labelOffset)
+        : patchOffset_(patchOffset), labelOffset_(labelOffset) {}
+
+    js::jit::CodeOffset patchOffset_;
+    size_t labelOffset_ = 0;
+  };
+
+  js::Vector<LabelPatch, 4, js::SystemAllocPolicy> labelPatches_;
+  void AddLabelPatch(js::jit::CodeOffset patchOffset, size_t labelOffset) {
+    js::AutoEnterOOMUnsafeRegion oomUnsafe;
+    if (!labelPatches_.emplaceBack(patchOffset, labelOffset)) {
+      oomUnsafe.crash("Irregexp label patch");
+    }
+  }
+
+  Mode mode_;
+  int num_registers_;
+  int num_capture_registers_;
+  js::jit::LiveGeneralRegisterSet savedRegisters_;
+
+ public:
+  using TableVector =
+      js::Vector<PseudoHandle<ByteArrayData>, 4, js::SystemAllocPolicy>;
+  TableVector& tables() { return tables_; }
+
+ private:
+  TableVector tables_;
+  void AddTable(PseudoHandle<ByteArrayData> table) {
+    js::AutoEnterOOMUnsafeRegion oomUnsafe;
+    if (!tables_.append(std::move(table))) {
+      oomUnsafe.crash("Irregexp table append");
+    }
+  }
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // RegexpMacroAssemblerArch_h