/* -*- 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_mips32_Architecture_mips32_h
#define jit_mips32_Architecture_mips32_h

#include "mozilla/EndianUtils.h"
#include "mozilla/MathAlgorithms.h"

#include <limits.h>
#include <stdint.h>

#include "jit/mips-shared/Architecture-mips-shared.h"

#include "js/Utility.h"

namespace js {
namespace jit {

static constexpr uint32_t ShadowStackSpace = 4 * sizeof(uintptr_t);

// These offsets are specific to nunboxing, and capture offsets into the
// components of a js::Value.
// Size of MIPS32 general purpose registers is 32 bits.
#if MOZ_LITTLE_ENDIAN()
static const int32_t NUNBOX32_TYPE_OFFSET = 4;
static const int32_t NUNBOX32_PAYLOAD_OFFSET = 0;
#else
static const int32_t NUNBOX32_TYPE_OFFSET = 0;
static const int32_t NUNBOX32_PAYLOAD_OFFSET = 4;
#endif

// MIPS32 can have two types of floating-point coprocessors modes:
// - FR=0 mode/ 32-bit FPRs - Historical default, there are 32 single
// precision registers and pairs of even and odd float registers are used as
// double precision registers. Example: f0 (double) is composed of
// f0 and f1 (single). Loongson3A FPU running in this mode doesn't allow
// use of odd registers for single precision arithmetic.
// - FR=1 mode/ 64-bit FPRs - In this case, there are 32 double precision
// register which can also be used as single precision registers. More info
// https://dmz-portal.imgtec.com/wiki/MIPS_O32_ABI_-_FR0_and_FR1_Interlinking

// Currently we enable 16 even single precision registers which can be also can
// be used as double precision registers. It enables jit code to run even on
// Loongson3A. It does not support FR=1 mode because MacroAssembler threats odd
// single precision registers as high parts of even double precision registers.
#ifdef __mips_fpr
static_assert(__mips_fpr == 32, "MIPS32 jit only supports FR=0 fpu mode.");
#endif

class FloatRegisters : public FloatRegistersMIPSShared {
 public:
  static const char* GetName(uint32_t i) {
    MOZ_ASSERT(i < RegisterIdLimit);
    return FloatRegistersMIPSShared::GetName(Encoding(i % 32));
  }

  static Encoding FromName(const char* name);

  static const uint32_t Total = 32;
  static const uint32_t TotalDouble = 16;
  static const uint32_t TotalSingle = 16;

  static const uint32_t Allocatable = 30;
  static const SetType AllSingleMask = (1ULL << TotalSingle) - 1;

  static const SetType AllDoubleMask = ((1ULL << TotalDouble) - 1)
                                       << TotalSingle;
  static const SetType AllMask = AllDoubleMask | AllSingleMask;

  // When saving all registers we only need to do is save double registers.
  static const uint32_t TotalPhys = 16;
  static const uint32_t RegisterIdLimit = 32;

  static_assert(sizeof(SetType) * 8 >= Total,
                "SetType should be large enough to enumerate all registers.");

  static const SetType NonVolatileMask =
      ((SetType(1) << (FloatRegisters::f20 >> 1)) |
       (SetType(1) << (FloatRegisters::f22 >> 1)) |
       (SetType(1) << (FloatRegisters::f24 >> 1)) |
       (SetType(1) << (FloatRegisters::f26 >> 1)) |
       (SetType(1) << (FloatRegisters::f28 >> 1)) |
       (SetType(1) << (FloatRegisters::f30 >> 1))) *
      ((1 << TotalSingle) + 1);

  static const SetType VolatileMask = AllMask & ~NonVolatileMask;

  static const SetType WrapperMask = VolatileMask;

  static const SetType NonAllocatableMask =
      (SetType(1) << (FloatRegisters::f18 >> 1)) * ((1 << TotalSingle) + 1);

  static const SetType AllocatableMask = AllMask & ~NonAllocatableMask;
};

class FloatRegister : public FloatRegisterMIPSShared {
 public:
  enum RegType {
    Single = 0x0,
    Double = 0x1,
  };

  typedef FloatRegisters Codes;
  typedef Codes::Code Code;
  typedef Codes::Encoding Encoding;

  Encoding code_ : 6;

 protected:
  RegType kind_ : 1;

 public:
  constexpr FloatRegister(uint32_t code, RegType kind = Double)
      : code_(Encoding(code)), kind_(kind) {}
  constexpr FloatRegister()
      : code_(FloatRegisters::invalid_freg), kind_(Double) {}

  bool operator==(const FloatRegister& other) const {
    MOZ_ASSERT(!isInvalid());
    MOZ_ASSERT(!other.isInvalid());
    return kind_ == other.kind_ && code_ == other.code_;
  }
  bool equiv(const FloatRegister& other) const { return other.kind_ == kind_; }
  size_t size() const { return (kind_ == Double) ? 8 : 4; }
  size_t pushSize() const { return size(); }

  bool isNotOdd() const { return !isInvalid() && ((code_ & 1) == 0); }

  bool isSingle() const { return kind_ == Single; }
  bool isDouble() const { return kind_ == Double; }
  bool isInvalid() const { return code_ == FloatRegisters::invalid_freg; }
  bool isSimd128() const { return false; }

  FloatRegister doubleOverlay() const;
  FloatRegister singleOverlay() const;

  FloatRegister asSingle() const { return singleOverlay(); }
  FloatRegister asDouble() const { return doubleOverlay(); }
  FloatRegister asSimd128() const { MOZ_CRASH("NYI"); }

  Code code() const {
    MOZ_ASSERT(isNotOdd());
    return Code((code_ >> 1) | (kind_ << 4));
  }
  Encoding encoding() const {
    MOZ_ASSERT(!isInvalid());
    return code_;
  }
  uint32_t id() const {
    MOZ_ASSERT(!isInvalid());
    return code_;
  }
  static FloatRegister FromCode(uint32_t i) {
    uint32_t code = i & 15;
    uint32_t kind = i >> 4;
    return FloatRegister(Encoding(code << 1), RegType(kind));
  }

  static FloatRegister FromIndex(uint32_t index, RegType kind) {
    MOZ_ASSERT(index < 16);
    return FloatRegister(Encoding(index << 1), kind);
  }

  bool volatile_() const {
    return !!((SetType(1) << code()) & FloatRegisters::VolatileMask);
  }
  const char* name() const { return FloatRegisters::GetName(code_); }
  bool operator!=(const FloatRegister& other) const {
    return other.kind_ != kind_ || code_ != other.code_;
  }
  bool aliases(const FloatRegister& other) {
    MOZ_ASSERT(isNotOdd());
    return code_ == other.code_;
  }
  uint32_t numAliased() const {
    MOZ_ASSERT(isNotOdd());
    return 2;
  }
  FloatRegister aliased(uint32_t aliasIdx) {
    MOZ_ASSERT(isNotOdd());

    if (aliasIdx == 0) {
      return *this;
    }
    MOZ_ASSERT(aliasIdx == 1);
    if (isDouble()) {
      return singleOverlay();
    }
    return doubleOverlay();
  }
  uint32_t numAlignedAliased() const {
    MOZ_ASSERT(isNotOdd());
    return 2;
  }
  FloatRegister alignedAliased(uint32_t aliasIdx) {
    MOZ_ASSERT(isNotOdd());

    if (aliasIdx == 0) {
      return *this;
    }
    MOZ_ASSERT(aliasIdx == 1);
    if (isDouble()) {
      return singleOverlay();
    }
    return doubleOverlay();
  }

  SetType alignedOrDominatedAliasedSet() const {
    MOZ_ASSERT(isNotOdd());
    return (SetType(1) << (code_ >> 1)) *
           ((1 << FloatRegisters::TotalSingle) + 1);
  }

  static constexpr RegTypeName DefaultType = RegTypeName::Float64;

  template <RegTypeName = DefaultType>
  static SetType LiveAsIndexableSet(SetType s) {
    return SetType(0);
  }

  template <RegTypeName Name = DefaultType>
  static SetType AllocatableAsIndexableSet(SetType s) {
    static_assert(Name != RegTypeName::Any, "Allocatable set are not iterable");
    return LiveAsIndexableSet<Name>(s);
  }

  static Code FromName(const char* name) {
    return FloatRegisters::FromName(name);
  }
  static TypedRegisterSet<FloatRegister> ReduceSetForPush(
      const TypedRegisterSet<FloatRegister>& s);
  static uint32_t GetPushSizeInBytes(const TypedRegisterSet<FloatRegister>& s);
  uint32_t getRegisterDumpOffsetInBytes();
};

template <>
inline FloatRegister::SetType
FloatRegister::LiveAsIndexableSet<RegTypeName::Float32>(SetType set) {
  return set & FloatRegisters::AllSingleMask;
}

template <>
inline FloatRegister::SetType
FloatRegister::LiveAsIndexableSet<RegTypeName::Float64>(SetType set) {
  return set & FloatRegisters::AllDoubleMask;
}

template <>
inline FloatRegister::SetType
FloatRegister::LiveAsIndexableSet<RegTypeName::Any>(SetType set) {
  return set;
}

template <>
inline FloatRegister::SetType
FloatRegister::AllocatableAsIndexableSet<RegTypeName::Float32>(SetType set) {
  // Single registers are not dominating any smaller registers, thus masking
  // is enough to convert an allocatable set into a set of register list all
  // single register available.
  return set & FloatRegisters::AllSingleMask;
}

template <>
inline FloatRegister::SetType
FloatRegister::AllocatableAsIndexableSet<RegTypeName::Float64>(SetType set) {
  return set & FloatRegisters::AllDoubleMask;
}

// In order to handle functions such as int(*)(int, double) where the first
// argument is a general purpose register, and the second argument is a floating
// point register, we have to store the double content into 2 general purpose
// registers, namely a2 and a3.
#define JS_CODEGEN_REGISTER_PAIR 1

}  // namespace jit
}  // namespace js

#endif /* jit_mips32_Architecture_mips32_h */