path: root/js/src/jit/RegisterSets.h

/* -*- 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/. */

#ifndef jit_RegisterSets_h
#define jit_RegisterSets_h

#include "mozilla/Assertions.h"
#include "mozilla/Attributes.h"
#include "mozilla/Variant.h"

#include <new>
#include <stddef.h>
#include <stdint.h>

#include "jit/IonTypes.h"
#include "jit/Registers.h"
#include "js/Value.h"

namespace js {
namespace jit {

struct AnyRegister {
  using Code = uint8_t;

  static const uint8_t Total = Registers::Total + FloatRegisters::Total;
  static const uint8_t FirstFloatReg = Registers::Total;
  static const uint8_t Invalid = UINT8_MAX;

  static_assert(size_t(Registers::Total) + FloatRegisters::Total <= UINT8_MAX,
                "Number of registers must fit in uint8_t");

 private:
  Code code_;

 public:
  AnyRegister() : code_(Invalid) {}

  explicit AnyRegister(Register gpr) { code_ = gpr.code(); }
  explicit AnyRegister(FloatRegister fpu) {
    code_ = fpu.code() + Registers::Total;
  }
  static AnyRegister FromCode(uint8_t i) {
    MOZ_ASSERT(i < Total);
    AnyRegister r;
    r.code_ = i;
    return r;
  }
  bool isFloat() const {
    MOZ_ASSERT(isValid());
    return code_ >= Registers::Total;
  }
  Register gpr() const {
    MOZ_ASSERT(!isFloat());
    return Register::FromCode(code_);
  }
  FloatRegister fpu() const {
    MOZ_ASSERT(isFloat());
    return FloatRegister::FromCode(code_ - Registers::Total);
  }
  bool operator==(AnyRegister other) const {
    // We don't need the operands to be valid to test for equality.
    return code_ == other.code_;
  }
  bool operator!=(AnyRegister other) const {
    // We don't need the operands to be valid to test for equality.
    return code_ != other.code_;
  }
  const char* name() const { return isFloat() ? fpu().name() : gpr().name(); }
  Code code() const {
    MOZ_ASSERT(isValid());
    return code_;
  }
  bool volatile_() const {
    return isFloat() ? fpu().volatile_() : gpr().volatile_();
  }
  AnyRegister aliased(uint8_t aliasIdx) const {
    AnyRegister ret;
    if (isFloat()) {
      ret = AnyRegister(fpu().aliased(aliasIdx));
    } else {
      ret = AnyRegister(gpr().aliased(aliasIdx));
    }
    MOZ_ASSERT_IF(aliasIdx == 0, ret == *this);
    return ret;
  }
  uint8_t numAliased() const {
    if (isFloat()) {
      return fpu().numAliased();
    }
    return gpr().numAliased();
  }
  bool aliases(const AnyRegister& other) const {
    if (isFloat() && other.isFloat()) {
      return fpu().aliases(other.fpu());
    }
    if (!isFloat() && !other.isFloat()) {
      return gpr().aliases(other.gpr());
    }
    return false;
  }
  // do the two registers hold the same type of data (e.g. both float32, both
  // gpr)
  bool isCompatibleReg(const AnyRegister other) const {
    if (isFloat() && other.isFloat()) {
      return fpu().equiv(other.fpu());
    }
    if (!isFloat() && !other.isFloat()) {
      return true;
    }
    return false;
  }
  bool isValid() const { return code_ != Invalid; }
};

// Registers to hold a boxed value. Uses one register on 64 bit
// platforms, two registers on 32 bit platforms.
class ValueOperand {
#if defined(JS_NUNBOX32)
  Register type_;
  Register payload_;

 public:
  constexpr ValueOperand(Register type, Register payload)
      : type_(type), payload_(payload) {}

  constexpr Register typeReg() const { return type_; }
  constexpr Register payloadReg() const { return payload_; }
  constexpr Register64 toRegister64() const {
    return Register64(typeReg(), payloadReg());
  }
  constexpr bool aliases(Register reg) const {
    return type_ == reg || payload_ == reg;
  }
  constexpr Register payloadOrValueReg() const { return payloadReg(); }
  bool hasVolatileReg() const {
    return type_.volatile_() || payload_.volatile_();
  }
  constexpr bool operator==(const ValueOperand& o) const {
    return type_ == o.type_ && payload_ == o.payload_;
  }
  constexpr bool operator!=(const ValueOperand& o) const {
    return !(*this == o);
  }

#elif defined(JS_PUNBOX64)
  Register value_;

 public:
  explicit constexpr ValueOperand(Register value) : value_(value) {}

  constexpr Register valueReg() const { return value_; }
  constexpr Register64 toRegister64() const { return Register64(valueReg()); }
  constexpr bool aliases(Register reg) const { return value_ == reg; }
  constexpr Register payloadOrValueReg() const { return valueReg(); }
  bool hasVolatileReg() const { return value_.volatile_(); }
  constexpr bool operator==(const ValueOperand& o) const {
    return value_ == o.value_;
  }
  constexpr bool operator!=(const ValueOperand& o) const {
    return !(*this == o);
  }
#endif

  constexpr Register scratchReg() const { return payloadOrValueReg(); }

  ValueOperand() = default;
};

// Registers to hold either either a typed or untyped value.
class TypedOrValueRegister {
  // Type of value being stored.
  MIRType type_;

  union U {
    AnyRegister::Code typed;
#if defined(JS_PUNBOX64)
    Register::Code value;
#elif defined(JS_NUNBOX32)
    struct {
      Register::Code valueType;
      Register::Code valuePayload;
    } s;
#else
#  error "Bad architecture"
#endif
  } data;

 public:
  TypedOrValueRegister() = default;

  TypedOrValueRegister(MIRType type, AnyRegister reg) : type_(type) {
    data.typed = reg.code();
  }

  MOZ_IMPLICIT TypedOrValueRegister(ValueOperand value)
      : type_(MIRType::Value) {
#if defined(JS_PUNBOX64)
    data.value = value.valueReg().code();
#elif defined(JS_NUNBOX32)
    data.s.valueType = value.typeReg().code();
    data.s.valuePayload = value.payloadReg().code();
#else
#  error "Bad architecture"
#endif
  }

  MIRType type() const { return type_; }

  bool hasTyped() const {
    return type() != MIRType::None && type() != MIRType::Value;
  }

  bool hasValue() const { return type() == MIRType::Value; }

  AnyRegister typedReg() const {
    MOZ_ASSERT(hasTyped());
    return AnyRegister::FromCode(data.typed);
  }

  ValueOperand valueReg() const {
    MOZ_ASSERT(hasValue());
#if defined(JS_PUNBOX64)
    return ValueOperand(Register::FromCode(data.value));
#elif defined(JS_NUNBOX32)
    return ValueOperand(Register::FromCode(data.s.valueType),
                        Register::FromCode(data.s.valuePayload));
#else
#  error "Bad architecture"
#endif
  }

  AnyRegister scratchReg() {
    if (hasValue()) {
      return AnyRegister(valueReg().scratchReg());
    }
    return typedReg();
  }
};

// A constant value, or registers to hold a typed/untyped value.
class ConstantOrRegister {
  // Whether a constant value is being stored.
  bool constant_;

  // Space to hold either a Value or a TypedOrValueRegister.
  union U {
    JS::Value constant;
    TypedOrValueRegister reg;

    // |constant| has a non-trivial constructor and therefore MUST be
    // placement-new'd into existence.
    MOZ_PUSH_DISABLE_NONTRIVIAL_UNION_WARNINGS
    U() {}
    MOZ_POP_DISABLE_NONTRIVIAL_UNION_WARNINGS
  } data;

 public:
  ConstantOrRegister() = delete;

  MOZ_IMPLICIT ConstantOrRegister(const JS::Value& value) : constant_(true) {
    MOZ_ASSERT(constant());
    new (&data.constant) JS::Value(value);
  }

  MOZ_IMPLICIT ConstantOrRegister(TypedOrValueRegister reg) : constant_(false) {
    MOZ_ASSERT(!constant());
    new (&data.reg) TypedOrValueRegister(reg);
  }

  bool constant() const { return constant_; }

  JS::Value value() const {
    MOZ_ASSERT(constant());
    return data.constant;
  }

  const TypedOrValueRegister& reg() const {
    MOZ_ASSERT(!constant());
    return data.reg;
  }
};

template <typename T>
class TypedRegisterSet {
 public:
  using RegType = T;
  using SetType = typename T::SetType;

 private:
  SetType bits_;

 public:
  explicit constexpr TypedRegisterSet(SetType bits) : bits_(bits) {}

  constexpr TypedRegisterSet() : bits_(0) {}
  constexpr TypedRegisterSet(const TypedRegisterSet<T>& set)
      : bits_(set.bits_) {}

  static inline TypedRegisterSet All() {
    return TypedRegisterSet(T::Codes::AllocatableMask);
  }
  static inline TypedRegisterSet Intersect(const TypedRegisterSet& lhs,
                                           const TypedRegisterSet& rhs) {
    return TypedRegisterSet(lhs.bits_ & rhs.bits_);
  }
  static inline TypedRegisterSet Union(const TypedRegisterSet& lhs,
                                       const TypedRegisterSet& rhs) {
    return TypedRegisterSet(lhs.bits_ | rhs.bits_);
  }
  static inline TypedRegisterSet Not(const TypedRegisterSet& in) {
    return TypedRegisterSet(~in.bits_ & T::Codes::AllocatableMask);
  }
  static inline TypedRegisterSet Subtract(const TypedRegisterSet& lhs,
                                          const TypedRegisterSet& rhs) {
    return TypedRegisterSet(lhs.bits_ & ~rhs.bits_);
  }
  static inline TypedRegisterSet VolatileNot(const TypedRegisterSet& in) {
    const SetType allocatableVolatile =
        T::Codes::AllocatableMask & T::Codes::VolatileMask;
    return TypedRegisterSet(~in.bits_ & allocatableVolatile);
  }
  static inline TypedRegisterSet Volatile() {
    return TypedRegisterSet(T::Codes::AllocatableMask & T::Codes::VolatileMask);
  }
  static inline TypedRegisterSet NonVolatile() {
    return TypedRegisterSet(T::Codes::AllocatableMask &
                            T::Codes::NonVolatileMask);
  }

  bool empty() const { return !bits_; }
  void clear() { bits_ = 0; }

  bool hasRegisterIndex(T reg) const {
    return !!(bits_ & (SetType(1) << reg.code()));
  }
  bool hasAllocatable(T reg) const {
    return !(~bits_ & reg.alignedOrDominatedAliasedSet());
  }

  void addRegisterIndex(T reg) { bits_ |= (SetType(1) << reg.code()); }
  void addAllocatable(T reg) { bits_ |= reg.alignedOrDominatedAliasedSet(); }

  void takeRegisterIndex(T reg) { bits_ &= ~(SetType(1) << reg.code()); }
  void takeAllocatable(T reg) { bits_ &= ~reg.alignedOrDominatedAliasedSet(); }

  static constexpr RegTypeName DefaultType = RegType::DefaultType;

  template <RegTypeName Name>
  SetType allLive() const {
    return T::template LiveAsIndexableSet<Name>(bits_);
  }
  template <RegTypeName Name>
  SetType allAllocatable() const {
    return T::template AllocatableAsIndexableSet<Name>(bits_);
  }

  static RegType FirstRegister(SetType set) {
    return RegType::FromCode(RegType::FirstBit(set));
  }
  static RegType LastRegister(SetType set) {
    return RegType::FromCode(RegType::LastBit(set));
  }

  SetType bits() const { return bits_; }
  uint32_t size() const { return T::SetSize(bits_); }
  bool operator==(const TypedRegisterSet<T>& other) const {
    return other.bits_ == bits_;
  }
  TypedRegisterSet<T> reduceSetForPush() const {
    return T::ReduceSetForPush(*this);
  }
  uint32_t getPushSizeInBytes() const { return T::GetPushSizeInBytes(*this); }

  size_t offsetOfPushedRegister(RegType reg) const {
    MOZ_ASSERT(hasRegisterIndex(reg));
    return T::OffsetOfPushedRegister(bits(), reg);
  }
};

using GeneralRegisterSet = TypedRegisterSet<Register>;
using FloatRegisterSet = TypedRegisterSet<FloatRegister>;

class AnyRegisterIterator;

class RegisterSet {
  GeneralRegisterSet gpr_;
  FloatRegisterSet fpu_;

  friend class AnyRegisterIterator;

 public:
  RegisterSet() = default;
  constexpr RegisterSet(const GeneralRegisterSet& gpr,
                        const FloatRegisterSet& fpu)
      : gpr_(gpr), fpu_(fpu) {}
  static inline RegisterSet All() {
    return RegisterSet(GeneralRegisterSet::All(), FloatRegisterSet::All());
  }
  static inline RegisterSet Intersect(const RegisterSet& lhs,
                                      const RegisterSet& rhs) {
    return RegisterSet(GeneralRegisterSet::Intersect(lhs.gpr_, rhs.gpr_),
                       FloatRegisterSet::Intersect(lhs.fpu_, rhs.fpu_));
  }
  static inline RegisterSet Union(const RegisterSet& lhs,
                                  const RegisterSet& rhs) {
    return RegisterSet(GeneralRegisterSet::Union(lhs.gpr_, rhs.gpr_),
                       FloatRegisterSet::Union(lhs.fpu_, rhs.fpu_));
  }
  static inline RegisterSet Not(const RegisterSet& in) {
    return RegisterSet(GeneralRegisterSet::Not(in.gpr_),
                       FloatRegisterSet::Not(in.fpu_));
  }
  static inline RegisterSet VolatileNot(const RegisterSet& in) {
    return RegisterSet(GeneralRegisterSet::VolatileNot(in.gpr_),
                       FloatRegisterSet::VolatileNot(in.fpu_));
  }
  static inline RegisterSet Volatile() {
    return RegisterSet(GeneralRegisterSet::Volatile(),
                       FloatRegisterSet::Volatile());
  }

  bool empty() const { return fpu_.empty() && gpr_.empty(); }
  void clear() {
    fpu_.clear();
    gpr_.clear();
  }
  bool emptyGeneral() const { return gpr_.empty(); }
  bool emptyFloat() const { return fpu_.empty(); }

  static constexpr RegTypeName DefaultType = RegTypeName::GPR;

  constexpr GeneralRegisterSet gprs() const { return gpr_; }
  GeneralRegisterSet& gprs() { return gpr_; }
  constexpr FloatRegisterSet fpus() const { return fpu_; }
  FloatRegisterSet& fpus() { return fpu_; }
  bool operator==(const RegisterSet& other) const {
    return other.gpr_ == gpr_ && other.fpu_ == fpu_;
  }
};

// [SMDOC] JIT Register-Set overview
//
// There are 2 use cases for register sets:
//
//   1. To serve as a pool of allocatable register. This is useful for working
//      on the code produced by some stub where free registers are available, or
//      when we can release some registers.
//
//   2. To serve as a list of typed registers. This is useful for working with
//      live registers and to manipulate them with the proper instructions. This
//      is used by the register allocator to fill the Safepoints.
//
// These 2 uses cases can be used on top of 3 different backend representation
// of register sets, which are either GeneralRegisterSet, FloatRegisterSet, or
// RegisterSet (for both). These classes are used to store the bit sets to
// represent each register.
//
// Each use case defines an Accessor class, such as AllocatableSetAccessor or
// LiveSetAccessor, which is parameterized with the type of the register
// set. These accessors are in charge of manipulating the register set in a
// consistent way.
//
// The RegSetCommonInterface class is used to wrap the accessors with convenient
// shortcuts which are based on the accessors.
//
// Then, to avoid to many levels of complexity while using these interfaces,
// shortcut templates are created to make it easy to distinguish between a
// register set used for allocating registers, or a register set used for making
// a collection of allocated (live) registers.
//
// This separation exists to prevent mixing LiveSet and AllocatableSet
// manipulations of the same register set, and ensure safety while avoiding
// false positive.

template <typename RegisterSet>
class AllocatableSet;

template <typename RegisterSet>
class LiveSet;

// [SMDOC] JIT Register-Set (Allocatable)
//
// Base accessors classes have the minimal set of raw methods to manipulate the
// register set given as parameter in a consistent manner.  These methods are:
//
//    - all<Type>: Returns a bit-set of all the register of a specific type
//      which are present.
//
//    - has: Returns if all the bits needed to take a register are present.
//
//    - takeUnchecked: Subtracts the bits used to represent the register in the
//      register set.
//
//    - addUnchecked: Adds the bits used to represent the register in the
//      register set.

// The AllocatableSet accessors are used to make a pool of unused
// registers. Taking or adding registers should consider the aliasing rules of
// the architecture.  For example, on ARM, the following piece of code should
// work fine, knowing that the double register |d0| is composed of float
// registers |s0| and |s1|:
//
//     AllocatableFloatRegisterSet regs;
//     regs.add(s0);
//     regs.add(s1);
//     // d0 is now available.
//     regs.take(d0);
//
// These accessors are useful for allocating registers within the functions used
// to generate stubs, trampolines, and inline caches (BaselineIC, IonCache).
template <typename Set>
class AllocatableSetAccessors {
 public:
  using RegSet = Set;
  using RegType = typename RegSet::RegType;
  using SetType = typename RegSet::SetType;

 protected:
  RegSet set_;

  template <RegTypeName Name>
  SetType all() const {
    return set_.template allAllocatable<Name>();
  }

 public:
  AllocatableSetAccessors() : set_() {}
  explicit constexpr AllocatableSetAccessors(SetType set) : set_(set) {}
  explicit constexpr AllocatableSetAccessors(RegSet set) : set_(set) {}

  bool has(RegType reg) const { return set_.hasAllocatable(reg); }

  template <RegTypeName Name>
  bool hasAny(RegType reg) const {
    return all<Name>() != 0;
  }

  void addUnchecked(RegType reg) { set_.addAllocatable(reg); }

  void takeUnchecked(RegType reg) { set_.takeAllocatable(reg); }
};

// Specialization of the AllocatableSet accessors for the RegisterSet aggregate.
template <>
class AllocatableSetAccessors<RegisterSet> {
 public:
  using RegSet = RegisterSet;
  using RegType = AnyRegister;
  using SetType = char;

 protected:
  RegisterSet set_;

  template <RegTypeName Name>
  GeneralRegisterSet::SetType allGpr() const {
    return set_.gprs().allAllocatable<Name>();
  }
  template <RegTypeName Name>
  FloatRegisterSet::SetType allFpu() const {
    return set_.fpus().allAllocatable<Name>();
  }

 public:
  AllocatableSetAccessors() : set_() {}
  explicit constexpr AllocatableSetAccessors(SetType) = delete;
  explicit constexpr AllocatableSetAccessors(RegisterSet set) : set_(set) {}

  bool has(Register reg) const { return set_.gprs().hasAllocatable(reg); }
  bool has(FloatRegister reg) const { return set_.fpus().hasAllocatable(reg); }

  void addUnchecked(Register reg) { set_.gprs().addAllocatable(reg); }
  void addUnchecked(FloatRegister reg) { set_.fpus().addAllocatable(reg); }

  void takeUnchecked(Register reg) { set_.gprs().takeAllocatable(reg); }
  void takeUnchecked(FloatRegister reg) { set_.fpus().takeAllocatable(reg); }
};

// [SMDOC] JIT Register-Set (Live)
//
// The LiveSet accessors are used to collect a list of allocated
// registers. Taking or adding a register should *not* consider the aliases, as
// we care about interpreting the registers with the correct type.  For example,
// on x64, where one float registers can be interpreted as an Simd128, a Double,
// or a Float, adding xmm0 as an Simd128, does not make the register available
// as a Double.
//
//     LiveFloatRegisterSet regs;
//     regs.add(xmm0.asSimd128());
//     regs.take(xmm0); // Assert!
//
// These accessors are useful for recording the result of a register allocator,
// such as what the Backtracking allocator do on the Safepoints.
template <typename Set>
class LiveSetAccessors {
 public:
  using RegSet = Set;
  using RegType = typename RegSet::RegType;
  using SetType = typename RegSet::SetType;

 protected:
  RegSet set_;

  template <RegTypeName Name>
  SetType all() const {
    return set_.template allLive<Name>();
  }

 public:
  LiveSetAccessors() : set_() {}
  explicit constexpr LiveSetAccessors(SetType set) : set_(set) {}
  explicit constexpr LiveSetAccessors(RegSet set) : set_(set) {}

  bool has(RegType reg) const { return set_.hasRegisterIndex(reg); }

  void addUnchecked(RegType reg) { set_.addRegisterIndex(reg); }

  void takeUnchecked(RegType reg) { set_.takeRegisterIndex(reg); }
};

// Specialization of the LiveSet accessors for the RegisterSet aggregate.
template <>
class LiveSetAccessors<RegisterSet> {
 public:
  using RegSet = RegisterSet;
  using RegType = AnyRegister;
  using SetType = char;

 protected:
  RegisterSet set_;

  template <RegTypeName Name>
  GeneralRegisterSet::SetType allGpr() const {
    return set_.gprs().allLive<Name>();
  }
  template <RegTypeName Name>
  FloatRegisterSet::SetType allFpu() const {
    return set_.fpus().allLive<Name>();
  }

 public:
  LiveSetAccessors() : set_() {}
  explicit constexpr LiveSetAccessors(SetType) = delete;
  explicit constexpr LiveSetAccessors(RegisterSet set) : set_(set) {}

  bool has(Register reg) const { return set_.gprs().hasRegisterIndex(reg); }
  bool has(FloatRegister reg) const {
    return set_.fpus().hasRegisterIndex(reg);
  }

  void addUnchecked(Register reg) { set_.gprs().addRegisterIndex(reg); }
  void addUnchecked(FloatRegister reg) { set_.fpus().addRegisterIndex(reg); }

  void takeUnchecked(Register reg) { set_.gprs().takeRegisterIndex(reg); }
  void takeUnchecked(FloatRegister reg) { set_.fpus().takeRegisterIndex(reg); }
};

#define DEFINE_ACCESSOR_CONSTRUCTORS_(REGSET)             \
  typedef typename Parent::RegSet RegSet;                 \
  typedef typename Parent::RegType RegType;               \
  typedef typename Parent::SetType SetType;               \
                                                          \
  constexpr REGSET() : Parent() {}                        \
  explicit constexpr REGSET(SetType set) : Parent(set) {} \
  explicit constexpr REGSET(RegSet set) : Parent(set) {}

// This class adds checked accessors on top of the unchecked variants defined by
// AllocatableSet and LiveSet accessors. Also it defines interface which are
// specialized to the register set implementation, such as |getAny| and
// |takeAny| variants.
template <class Accessors, typename Set>
class SpecializedRegSet : public Accessors {
  using Parent = Accessors;

 public:
  DEFINE_ACCESSOR_CONSTRUCTORS_(SpecializedRegSet)

  SetType bits() const { return this->Parent::set_.bits(); }

  using Parent::has;

  using Parent::addUnchecked;
  void add(RegType reg) {
    MOZ_ASSERT(!this->has(reg));
    addUnchecked(reg);
  }

  using Parent::takeUnchecked;
  void take(RegType reg) {
    MOZ_ASSERT(this->has(reg));
    takeUnchecked(reg);
  }

  template <RegTypeName Name>
  bool hasAny() const {
    return Parent::template all<Name>() != 0;
  }

  template <RegTypeName Name = RegSet::DefaultType>
  RegType getFirst() const {
    SetType set = Parent::template all<Name>();
    MOZ_ASSERT(set);
    return RegSet::FirstRegister(set);
  }
  template <RegTypeName Name = RegSet::DefaultType>
  RegType getLast() const {
    SetType set = Parent::template all<Name>();
    MOZ_ASSERT(set);
    return RegSet::LastRegister(set);
  }
  template <RegTypeName Name = RegSet::DefaultType>
  RegType getAny() const {
    // The choice of first or last here is mostly arbitrary, as they are
    // about the same speed on popular architectures. We choose first, as
    // it has the advantage of using the "lower" registers more often. These
    // registers are sometimes more efficient (e.g. optimized encodings for
    // EAX on x86).
    return getFirst<Name>();
  }

  template <RegTypeName Name = RegSet::DefaultType>
  RegType getAnyExcluding(RegType preclude) {
    if (!this->has(preclude)) {
      return getAny<Name>();
    }

    take(preclude);
    RegType result = getAny<Name>();
    add(preclude);
    return result;
  }

  template <RegTypeName Name = RegSet::DefaultType>
  RegType takeAny() {
    RegType reg = getAny<Name>();
    take(reg);
    return reg;
  }
  template <RegTypeName Name = RegSet::DefaultType>
  RegType takeFirst() {
    RegType reg = getFirst<Name>();
    take(reg);
    return reg;
  }
  template <RegTypeName Name = RegSet::DefaultType>
  RegType takeLast() {
    RegType reg = getLast<Name>();
    take(reg);
    return reg;
  }

  ValueOperand takeAnyValue() {
#if defined(JS_NUNBOX32)
    return ValueOperand(takeAny<RegTypeName::GPR>(),
                        takeAny<RegTypeName::GPR>());
#elif defined(JS_PUNBOX64)
    return ValueOperand(takeAny<RegTypeName::GPR>());
#else
#  error "Bad architecture"
#endif
  }

  bool aliases(ValueOperand v) const {
#ifdef JS_NUNBOX32
    return this->has(v.typeReg()) || this->has(v.payloadReg());
#else
    return this->has(v.valueReg());
#endif
  }

  template <RegTypeName Name = RegSet::DefaultType>
  RegType takeAnyExcluding(RegType preclude) {
    RegType reg = getAnyExcluding<Name>(preclude);
    take(reg);
    return reg;
  }
};

// Specialization of the accessors for the RegisterSet aggregate.
template <class Accessors>
class SpecializedRegSet<Accessors, RegisterSet> : public Accessors {
  using Parent = Accessors;

 public:
  DEFINE_ACCESSOR_CONSTRUCTORS_(SpecializedRegSet)

  GeneralRegisterSet gprs() const { return this->Parent::set_.gprs(); }
  GeneralRegisterSet& gprs() { return this->Parent::set_.gprs(); }
  FloatRegisterSet fpus() const { return this->Parent::set_.fpus(); }
  FloatRegisterSet& fpus() { return this->Parent::set_.fpus(); }

  bool emptyGeneral() const { return this->Parent::set_.emptyGeneral(); }
  bool emptyFloat() const { return this->Parent::set_.emptyFloat(); }

  using Parent::has;
  bool has(AnyRegister reg) const {
    return reg.isFloat() ? this->has(reg.fpu()) : this->has(reg.gpr());
  }

  template <RegTypeName Name>
  bool hasAny() const {
    if (Name == RegTypeName::GPR) {
      return Parent::template allGpr<RegTypeName::GPR>() != 0;
    }
    return Parent::template allFpu<Name>() != 0;
  }

  using Parent::addUnchecked;
  void addUnchecked(AnyRegister reg) {
    if (reg.isFloat()) {
      addUnchecked(reg.fpu());
    } else {
      addUnchecked(reg.gpr());
    }
  }

  void add(Register reg) {
    MOZ_ASSERT(!this->has(reg));
    addUnchecked(reg);
  }
  void add(FloatRegister reg) {
    MOZ_ASSERT(!this->has(reg));
    addUnchecked(reg);
  }
  void add(AnyRegister reg) {
    if (reg.isFloat()) {
      add(reg.fpu());
    } else {
      add(reg.gpr());
    }
  }

  using Parent::takeUnchecked;
  void takeUnchecked(AnyRegister reg) {
    if (reg.isFloat()) {
      takeUnchecked(reg.fpu());
    } else {
      takeUnchecked(reg.gpr());
    }
  }

  void take(Register reg) {
#ifdef DEBUG
    bool hasReg = this->has(reg);
    MOZ_ASSERT(hasReg);
#endif
    takeUnchecked(reg);
  }
  void take(FloatRegister reg) {
    MOZ_ASSERT(this->has(reg));
    takeUnchecked(reg);
  }
  void take(AnyRegister reg) {
    if (reg.isFloat()) {
      take(reg.fpu());
    } else {
      take(reg.gpr());
    }
  }

  Register getAnyGeneral() const {
    GeneralRegisterSet::SetType set =
        Parent::template allGpr<RegTypeName::GPR>();
    MOZ_ASSERT(set);
    return GeneralRegisterSet::FirstRegister(set);
  }
  template <RegTypeName Name = RegTypeName::Float64>
  FloatRegister getAnyFloat() const {
    FloatRegisterSet::SetType set = Parent::template allFpu<Name>();
    MOZ_ASSERT(set);
    return FloatRegisterSet::FirstRegister(set);
  }

  Register takeAnyGeneral() {
    Register reg = getAnyGeneral();
    take(reg);
    return reg;
  }
  template <RegTypeName Name = RegTypeName::Float64>
  FloatRegister takeAnyFloat() {
    FloatRegister reg = getAnyFloat<Name>();
    take(reg);
    return reg;
  }
  ValueOperand takeAnyValue() {
#if defined(JS_NUNBOX32)
    return ValueOperand(takeAnyGeneral(), takeAnyGeneral());
#elif defined(JS_PUNBOX64)
    return ValueOperand(takeAnyGeneral());
#else
#  error "Bad architecture"
#endif
  }
};

// Interface which is common to all register set implementations. It overloads
// |add|, |take| and |takeUnchecked| methods for types such as |ValueOperand|,
// |TypedOrValueRegister|, and |Register64|.
template <class Accessors, typename Set>
class CommonRegSet : public SpecializedRegSet<Accessors, Set> {
  typedef SpecializedRegSet<Accessors, Set> Parent;

 public:
  DEFINE_ACCESSOR_CONSTRUCTORS_(CommonRegSet)

  RegSet set() const { return this->Parent::set_; }
  RegSet& set() { return this->Parent::set_; }

  bool empty() const { return this->Parent::set_.empty(); }
  void clear() { this->Parent::set_.clear(); }

  using Parent::add;
  void add(ValueOperand value) {
#if defined(JS_NUNBOX32)
    add(value.payloadReg());
    add(value.typeReg());
#elif defined(JS_PUNBOX64)
    add(value.valueReg());
#else
#  error "Bad architecture"
#endif
  }
  void add(Register64 reg) {
#if JS_BITS_PER_WORD == 32
    add(reg.high);
    add(reg.low);
#else
    add(reg.reg);
#endif
  }

  using Parent::addUnchecked;
  void addUnchecked(ValueOperand value) {
#if defined(JS_NUNBOX32)
    addUnchecked(value.payloadReg());
    addUnchecked(value.typeReg());
#elif defined(JS_PUNBOX64)
    addUnchecked(value.valueReg());
#else
#  error "Bad architecture"
#endif
  }
  void addUnchecked(Register64 reg) {
#if JS_BITS_PER_WORD == 32
    take(reg.high);
    take(reg.low);
#else
    take(reg.reg);
#endif
  }

  void add(TypedOrValueRegister reg) {
    if (reg.hasValue()) {
      add(reg.valueReg());
    } else if (reg.hasTyped()) {
      add(reg.typedReg());
    }
  }

  using Parent::take;
  void take(ValueOperand value) {
#if defined(JS_NUNBOX32)
    take(value.payloadReg());
    take(value.typeReg());
#elif defined(JS_PUNBOX64)
    take(value.valueReg());
#else
#  error "Bad architecture"
#endif
  }
  void take(TypedOrValueRegister reg) {
    if (reg.hasValue()) {
      take(reg.valueReg());
    } else if (reg.hasTyped()) {
      take(reg.typedReg());
    }
  }
  void take(Register64 reg) {
#if JS_BITS_PER_WORD == 32
    take(reg.high);
    take(reg.low);
#else
    take(reg.reg);
#endif
  }

  using Parent::takeUnchecked;
  void takeUnchecked(ValueOperand value) {
#if defined(JS_NUNBOX32)
    takeUnchecked(value.payloadReg());
    takeUnchecked(value.typeReg());
#elif defined(JS_PUNBOX64)
    takeUnchecked(value.valueReg());
#else
#  error "Bad architecture"
#endif
  }
  void takeUnchecked(TypedOrValueRegister reg) {
    if (reg.hasValue()) {
      takeUnchecked(reg.valueReg());
    } else if (reg.hasTyped()) {
      takeUnchecked(reg.typedReg());
    }
  }
  void takeUnchecked(Register64 reg) {
#if JS_BITS_PER_WORD == 32
    takeUnchecked(reg.high);
    takeUnchecked(reg.low);
#else
    takeUnchecked(reg.reg);
#endif
  }
};

// These classes do not provide any additional members, they only use their
// constructors to forward to the common interface for all register sets.  The
// only benefit of these classes is to provide user friendly names.
template <typename Set>
class LiveSet : public CommonRegSet<LiveSetAccessors<Set>, Set> {
  typedef CommonRegSet<LiveSetAccessors<Set>, Set> Parent;

 public:
  DEFINE_ACCESSOR_CONSTRUCTORS_(LiveSet)
};

template <typename Set>
class AllocatableSet : public CommonRegSet<AllocatableSetAccessors<Set>, Set> {
  typedef CommonRegSet<AllocatableSetAccessors<Set>, Set> Parent;

 public:
  DEFINE_ACCESSOR_CONSTRUCTORS_(AllocatableSet)

  LiveSet<Set> asLiveSet() const { return LiveSet<Set>(this->set()); }
};

#define DEFINE_ACCESSOR_CONSTRUCTORS_FOR_REGISTERSET_(REGSET)          \
  typedef Parent::RegSet RegSet;                                       \
  typedef Parent::RegType RegType;                                     \
  typedef Parent::SetType SetType;                                     \
                                                                       \
  constexpr REGSET() : Parent() {}                                     \
  explicit constexpr REGSET(SetType) = delete;                         \
  explicit constexpr REGSET(RegSet set) : Parent(set) {}               \
  constexpr REGSET(GeneralRegisterSet gpr, FloatRegisterSet fpu)       \
      : Parent(RegisterSet(gpr, fpu)) {}                               \
  REGSET(REGSET<GeneralRegisterSet> gpr, REGSET<FloatRegisterSet> fpu) \
      : Parent(RegisterSet(gpr.set(), fpu.set())) {}

template <>
class LiveSet<RegisterSet>
    : public CommonRegSet<LiveSetAccessors<RegisterSet>, RegisterSet> {
  // Note: We have to provide a qualified name for LiveSetAccessors, as it is
  // interpreted as being the specialized class name inherited from the parent
  // class specialization.
  typedef CommonRegSet<jit::LiveSetAccessors<RegisterSet>, RegisterSet> Parent;

 public:
  DEFINE_ACCESSOR_CONSTRUCTORS_FOR_REGISTERSET_(LiveSet)
};

template <>
class AllocatableSet<RegisterSet>
    : public CommonRegSet<AllocatableSetAccessors<RegisterSet>, RegisterSet> {
  // Note: We have to provide a qualified name for AllocatableSetAccessors, as
  // it is interpreted as being the specialized class name inherited from the
  // parent class specialization.
  typedef CommonRegSet<jit::AllocatableSetAccessors<RegisterSet>, RegisterSet>
      Parent;

 public:
  DEFINE_ACCESSOR_CONSTRUCTORS_FOR_REGISTERSET_(AllocatableSet)

  LiveSet<RegisterSet> asLiveSet() const {
    return LiveSet<RegisterSet>(this->set());
  }
};

#undef DEFINE_ACCESSOR_CONSTRUCTORS_FOR_REGISTERSET_
#undef DEFINE_ACCESSOR_CONSTRUCTORS_

using AllocatableGeneralRegisterSet = AllocatableSet<GeneralRegisterSet>;
using AllocatableFloatRegisterSet = AllocatableSet<FloatRegisterSet>;
using AllocatableRegisterSet = AllocatableSet<RegisterSet>;

using LiveGeneralRegisterSet = LiveSet<GeneralRegisterSet>;
using LiveFloatRegisterSet = LiveSet<FloatRegisterSet>;
using LiveRegisterSet = LiveSet<RegisterSet>;

// iterates in whatever order happens to be convenient.
// Use TypedRegisterBackwardIterator or TypedRegisterForwardIterator if a
// specific order is required.
template <typename T>
class TypedRegisterIterator {
  LiveSet<TypedRegisterSet<T>> regset_;

 public:
  explicit TypedRegisterIterator(TypedRegisterSet<T> regset)
      : regset_(regset) {}
  explicit TypedRegisterIterator(LiveSet<TypedRegisterSet<T>> regset)
      : regset_(regset) {}
  TypedRegisterIterator(const TypedRegisterIterator& other)
      : regset_(other.regset_) {}

  bool more() const { return !regset_.empty(); }
  TypedRegisterIterator<T>& operator++() {
    regset_.template takeAny<RegTypeName::Any>();
    return *this;
  }
  T operator*() const { return regset_.template getAny<RegTypeName::Any>(); }
};

// iterates backwards, that is, rn to r0
template <typename T>
class TypedRegisterBackwardIterator {
  LiveSet<TypedRegisterSet<T>> regset_;

 public:
  explicit TypedRegisterBackwardIterator(TypedRegisterSet<T> regset)
      : regset_(regset) {}
  explicit TypedRegisterBackwardIterator(LiveSet<TypedRegisterSet<T>> regset)
      : regset_(regset) {}
  TypedRegisterBackwardIterator(const TypedRegisterBackwardIterator& other)
      : regset_(other.regset_) {}

  bool more() const { return !regset_.empty(); }
  TypedRegisterBackwardIterator<T>& operator++() {
    regset_.template takeLast<RegTypeName::Any>();
    return *this;
  }
  T operator*() const { return regset_.template getLast<RegTypeName::Any>(); }
};

// iterates forwards, that is r0 to rn
template <typename T>
class TypedRegisterForwardIterator {
  LiveSet<TypedRegisterSet<T>> regset_;

 public:
  explicit TypedRegisterForwardIterator(TypedRegisterSet<T> regset)
      : regset_(regset) {}
  explicit TypedRegisterForwardIterator(LiveSet<TypedRegisterSet<T>> regset)
      : regset_(regset) {}
  TypedRegisterForwardIterator(const TypedRegisterForwardIterator& other)
      : regset_(other.regset_) {}

  bool more() const { return !regset_.empty(); }
  TypedRegisterForwardIterator<T>& operator++() {
    regset_.template takeFirst<RegTypeName::Any>();
    return *this;
  }
  T operator*() const { return regset_.template getFirst<RegTypeName::Any>(); }
};

using GeneralRegisterIterator = TypedRegisterIterator<Register>;
using FloatRegisterIterator = TypedRegisterIterator<FloatRegister>;
using GeneralRegisterBackwardIterator = TypedRegisterBackwardIterator<Register>;
using FloatRegisterBackwardIterator =
    TypedRegisterBackwardIterator<FloatRegister>;
using GeneralRegisterForwardIterator = TypedRegisterForwardIterator<Register>;
using FloatRegisterForwardIterator =
    TypedRegisterForwardIterator<FloatRegister>;

class AnyRegisterIterator {
  GeneralRegisterIterator geniter_;
  FloatRegisterIterator floatiter_;

 public:
  AnyRegisterIterator()
      : geniter_(GeneralRegisterSet::All()),
        floatiter_(FloatRegisterSet::All()) {}
  AnyRegisterIterator(GeneralRegisterSet genset, FloatRegisterSet floatset)
      : geniter_(genset), floatiter_(floatset) {}
  explicit AnyRegisterIterator(const RegisterSet& set)
      : geniter_(set.gpr_), floatiter_(set.fpu_) {}
  explicit AnyRegisterIterator(const LiveSet<RegisterSet>& set)
      : geniter_(set.gprs()), floatiter_(set.fpus()) {}
  AnyRegisterIterator(const AnyRegisterIterator& other) = default;
  bool more() const { return geniter_.more() || floatiter_.more(); }
  AnyRegisterIterator& operator++() {
    if (geniter_.more()) {
      ++geniter_;
    } else {
      ++floatiter_;
    }
    return *this;
  }
  AnyRegister operator*() const {
    if (geniter_.more()) {
      return AnyRegister(*geniter_);
    }
    return AnyRegister(*floatiter_);
  }
};

class ABIArg {
 public:
  enum Kind {
    GPR,
#ifdef JS_CODEGEN_REGISTER_PAIR
    GPR_PAIR,
#endif
    FPU,
    Stack,
    Uninitialized = -1
  };

 private:
  Kind kind_;
  union {
    Register::Code gpr_;
    FloatRegister::Code fpu_;
    uint32_t offset_;
  } u;

 public:
  ABIArg() : kind_(Uninitialized) { u.offset_ = -1; }
  explicit ABIArg(Register gpr) : kind_(GPR) { u.gpr_ = gpr.code(); }
  explicit ABIArg(Register gprLow, Register gprHigh) {
#if defined(JS_CODEGEN_REGISTER_PAIR)
    kind_ = GPR_PAIR;
#else
    MOZ_CRASH("Unsupported type of ABI argument.");
#endif
    u.gpr_ = gprLow.code();
    MOZ_ASSERT(u.gpr_ % 2 == 0);
    MOZ_ASSERT(u.gpr_ + 1 == gprHigh.code());
  }
  explicit ABIArg(FloatRegister fpu) : kind_(FPU) { u.fpu_ = fpu.code(); }
  explicit ABIArg(uint32_t offset) : kind_(Stack) { u.offset_ = offset; }

  Kind kind() const {
    MOZ_ASSERT(kind_ != Uninitialized);
    return kind_;
  }
#ifdef JS_CODEGEN_REGISTER_PAIR
  bool isGeneralRegPair() const { return kind() == GPR_PAIR; }
#else
  bool isGeneralRegPair() const { return false; }
#endif

  Register gpr() const {
    MOZ_ASSERT(kind() == GPR);
    return Register::FromCode(u.gpr_);
  }
  Register64 gpr64() const {
#ifdef JS_PUNBOX64
    return Register64(gpr());
#else
    return Register64(oddGpr(), evenGpr());
#endif
  }
  Register evenGpr() const {
    MOZ_ASSERT(isGeneralRegPair());
    return Register::FromCode(u.gpr_);
  }
  Register oddGpr() const {
    MOZ_ASSERT(isGeneralRegPair());
    return Register::FromCode(u.gpr_ + 1);
  }
  FloatRegister fpu() const {
    MOZ_ASSERT(kind() == FPU);
    return FloatRegister::FromCode(u.fpu_);
  }
  uint32_t offsetFromArgBase() const {
    MOZ_ASSERT(kind() == Stack);
    return u.offset_;
  }

  bool argInRegister() const { return kind() != Stack; }
  AnyRegister reg() const {
    return kind() == GPR ? AnyRegister(gpr()) : AnyRegister(fpu());
  }

  bool operator==(const ABIArg& rhs) const {
    if (kind_ != rhs.kind_) {
      return false;
    }

    switch (kind_) {
      case GPR:
        return u.gpr_ == rhs.u.gpr_;
#if defined(JS_CODEGEN_REGISTER_PAIR)
      case GPR_PAIR:
        return u.gpr_ == rhs.u.gpr_;
#endif
      case FPU:
        return u.fpu_ == rhs.u.fpu_;
      case Stack:
        return u.offset_ == rhs.u.offset_;
      case Uninitialized:
        return true;
    }
    MOZ_CRASH("Invalid value for ABIArg kind");
  }

  bool operator!=(const ABIArg& rhs) const { return !(*this == rhs); }
};

// Get the set of registers which should be saved by a block of code which
// clobbers all registers besides |unused|, but does not clobber floating point
// registers.
inline LiveGeneralRegisterSet SavedNonVolatileRegisters(
    const AllocatableGeneralRegisterSet& unused) {
  LiveGeneralRegisterSet result;

  for (GeneralRegisterIterator iter(GeneralRegisterSet::NonVolatile());
       iter.more(); ++iter) {
    Register reg = *iter;
    if (!unused.has(reg)) {
      result.add(reg);
    }
  }

  // Some platforms require the link register to be saved, if calls can be made.
#if defined(JS_CODEGEN_ARM)
  result.add(Register::FromCode(Registers::lr));
#elif defined(JS_CODEGEN_ARM64)
  result.add(Register::FromCode(Registers::lr));
#elif defined(JS_CODEGEN_MIPS32) || defined(JS_CODEGEN_MIPS64) || \
    defined(JS_CODEGEN_LOONG64) || defined(JS_CODEGEN_RISCV64)
  result.add(Register::FromCode(Registers::ra));
#endif

  return result;
}

}  // namespace jit
}  // namespace js

#endif /* jit_RegisterSets_h */