src/arch/generic/vec_reg.hh - arm/gem5 - Git at Google

 /*
  * Copyright (c) 2015-2016 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
  * not be construed as granting a license to any other intellectual
  * property including but not limited to intellectual property relating
  * to a hardware implementation of the functionality of the software
  * licensed hereunder.  You may use the software subject to the license
  * terms below provided that you ensure that this notice is replicated
  * unmodified and in its entirety in all distributions of the software,
  * modified or unmodified, in source code or in binary form.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met: redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer;
  * redistributions in binary form must reproduce the above copyright
  * notice, this list of conditions and the following disclaimer in the
  * documentation and/or other materials provided with the distribution;
  * neither the name of the copyright holders nor the names of its
  * contributors may be used to endorse or promote products derived from
  * this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  * Authors: Giacomo Gabrielli
  *          Nathanael Premillieu
  *          Rekai Gonzalez
  */

 /** \file arch/generic/vec_reg.hh
  * Vector Registers layout specification.
  *
  * This register type is to be used to model the SIMD registers.
  * It takes into account the possibility that different architectural names
  * may overlap (like for ARMv8 AArch32 for example).
  *
  * The design is having a basic vector register container that holds the
  * bytes, unaware of anything else. This is implemented by VecRegContainer.
  * As the (maximum) length of the physical vector register is a compile-time
  * constant, it is defined as a template parameter.
  *
  * This file also describes two views of the container that have semantic
  * information about the bytes. The first of this views is VecRegT.
  *    A VecRegT is a view of a VecRegContainer (by reference). The VecRegT has
  *    a type (VecElem) to which bytes are casted, and the amount of such
  *    elements that the vector contains (NumElems). The size of a view,
  *    calculated as sizeof(VecElem) * NumElems must match the size of the
  *    underlying container. As VecRegT has some degree of type information it
  *    has vector semantics, and defines the index operator ([]) to get
  *    references to particular bytes understood as a VecElem.
  * The second view of a container implemented in this file is VecLaneT, which
  * is a view of a subset of the container.
  *    A VecLaneT is a view of a lane of a vector register, where a lane is
  *    identified by a type (VecElem) and an index (although the view is
  *    unaware of its index). Operations on the lane are directly applied to
  *    the corresponding bytes of the underlying VecRegContainer through a
  *    reference.
  *
  * The intended usage is requesting views to the VecRegContainer via the
  * member 'as' for VecRegT and the member 'laneView' for VecLaneT. Kindly
  * find an example of usage in the following.
  *
  *
  * // We declare 512 bits vectors
  * using Vec512 = VecRegContainer<64>;
  * ...
  * // We implement the physical vector register file
  * Vec512 physicalVecRegFile[NUM_VREGS];
  * ...
  * // Usage example, for a macro op:
  * VecFloat8Add(ExecContext* xd) {
  *    // Request source vector register to the execution context (const as it
  *    // is read only).
  *    const Vec512& vsrc1raw = xc->readVecRegOperand(this, 0);
  *    // View it as a vector of floats (we could just specify the first
  *    // template parametre, the second has a default value that works, and the
  *    // last one is derived by the constness of vsrc1raw).
  *    VecRegT<float, 8, true>& vsrc1 = vsrc1raw->as<float, 8>();
  *
  *    // Second source and view
  *    const Vec512& vsrc2raw = xc->readVecRegOperand(this, 1);
  *    VecRegT<float, 8, true>& vsrc2 = vsrc2raw->as<float, 8>();
  *
  *    // Destination and view
  *    Vec512 vdstraw;
  *    VecRegT<float, 8, false>& vdst = vdstraw->as<float, 8>();
  *
  *    for (auto i = 0; i < 8; i++) {
  *        // This asignment sets the bits in the underlying Vec512: vdstraw
  *        vdst[i] = vsrc1[i] + vsrc2[i];
  *    }
  *    xc->setWriteRegOperand(this, 0, vdstraw);
  * }
  *
  * // Usage example, for a micro op that operates over lane number _lidx:
  * VecFloatLaneAdd(ExecContext* xd) {
  *    // Request source vector register to the execution context (const as it
  *    // is read only).
  *    const Vec512& vsrc1raw = xc->readVecRegOperand(this, 0);
  *    // View it as a lane of a vector of floats (we could just specify the
  *    // first template parametre, the second is derived by the constness of
  *    // vsrc1raw).
  *    VecLaneT<float, true>& src1 = vsrc1raw->laneView<float>(this->_lidx);
  *
  *    // Second source and view
  *    const Vec512& vsrc2raw = xc->readVecRegOperand(this, 1);
  *    VecLaneT<float, true>& src2 = vsrc2raw->laneView<float>(this->_lidx);
  *
  *    // (Writable) destination and view
  *    // As this is a partial write, we need the exec context to support that
  *    // through, e.g., 'readVecRegOperandToWrite' returning a writable
  *    // reference to the register
  *    Vec512 vdstraw = xc->readVecRegOperandToWrite(this, 3);
  *    VecLaneT<float, false>& dst = vdstraw->laneView<float>(this->_lidx);
  *
  *    dst = src1 + src2;
  *    // There is no need to copy the value back into the exec context, as
  *    // the assignment to dst modifies the appropriate bytes in vdstraw which
  *    // is in turn, a reference to the register in the cpu model.
  *    // For operations that do conditional writeback, we can decouple the
  *    // write by doing:
  *    //   auto tmp = src1 + src2;
  *    //   if (test) {
  *    //       dst = tmp; // do writeback
  *    //   } else {
  *    //      // do not do writeback
  *    //   }
  * }
  *
  */

 #ifndef __ARCH_GENERIC_VEC_REG_HH__
 #define __ARCH_GENERIC_VEC_REG_HH__

 #include <array>
 #include <cassert>
 #include <iostream>
 #include <string>
 #include <type_traits>
 #include <vector>

 #include "base/cprintf.hh"
 #include "base/misc.hh"

 template <size_t Sz>
 class VecRegContainer;

 /** Vector Register Abstraction
  * This generic class is a view in a particularization of MVC, to vector
  * registers. There is a VecRegContainer that implements the model, and
  * contains the data. To that model we can interpose different instantiations
  * of VecRegT to view the container as a vector of NumElems elems of type
  * VecElem.
  * @tparam VecElem Type of each element of the vector.
  * @tparam NumElems Amount of components of the vector.
  * @tparam Const Indicate if the underlying container can be modified through
  * the view.
  */
 template <typename VecElem, size_t NumElems, bool Const>
 class VecRegT
 {
     /** Size of the register in bytes. */
     static constexpr size_t SIZE = sizeof(VecElem) * NumElems;
   public:
     /** Container type alias. */
     using Container = typename std::conditional<Const,
                                               const VecRegContainer<SIZE>,
                                               VecRegContainer<SIZE>>::type;
   private:
     /** My type alias. */
     using MyClass = VecRegT<VecElem, NumElems, Const>;
     /** Reference to container. */
     Container& container;

   public:
     /** Constructor. */
     VecRegT(Container& cnt) : container(cnt) {};

     /** Zero the container. */
     template<bool Condition = !Const>
     typename std::enable_if<Condition, void>::type
     zero() { container.zero(); }

     template<bool Condition = !Const>
     typename std::enable_if<Condition, MyClass&>::type
     operator=(const MyClass& that)
     {
         container = that.container;
         return *this;
     }

     /** Index operator. */
     const VecElem& operator[](size_t idx) const
     {
         return container.template raw_ptr<VecElem>()[idx];
     }

     /** Index operator. */
     template<bool Condition = !Const>
     typename std::enable_if<Condition, VecElem&>::type
     operator[](size_t idx)
     {
         return container.template raw_ptr<VecElem>()[idx];
     }

     /** Equality operator.
      * Required to compare thread contexts.
      */
     template<typename VE2, size_t NE2, bool C2>
     bool
     operator==(const VecRegT<VE2, NE2, C2>& that) const
     {
         return container == that.container;
     }
     /** Inequality operator.
      * Required to compare thread contexts.
      */
     template<typename VE2, size_t NE2, bool C2>
     bool
     operator!=(const VecRegT<VE2, NE2, C2>& that) const
     {
         return !operator==(that);
     }

     /** Output stream operator. */
     friend std::ostream&
     operator<<(std::ostream& os, const MyClass& vr)
     {
         /* 0-sized is not allowed */
         os << "[" << std::hex << (uint32_t)vr[0];
         for (uint32_t e = 1; e < vr.SIZE; e++)
             os << " " << std::hex << (uint32_t)vr[e];
         os << ']';
         return os;
     }

     const std::string print() const { return csprintf("%s", *this); }
     /**
      * Cast to VecRegContainer&
      * It is useful to get the reference to the container for ISA tricks,
      * because casting to reference prevents unnecessary copies.
      */
     operator Container&() { return container; }
 };

 /* Forward declaration. */
 template <typename VecElem, bool Const>
 class VecLaneT;

 /**
  * Vector Register Abstraction
  * This generic class is the model in a particularization of MVC, to vector
  * registers. The model has functionality to create views of itself, or a
  * portion through the method 'as
  * @tparam Sz Size of the container in bytes.
  */
 template <size_t Sz>
 class VecRegContainer
 {
   static_assert(Sz > 0,
           "Cannot create Vector Register Container of zero size");
   public:
     static constexpr size_t SIZE = Sz;
     using Container = std::array<uint8_t,Sz>;
   private:
     Container container;
     using MyClass = VecRegContainer<SIZE>;

   public:
     VecRegContainer() {}
     /* This is required for de-serialisation. */
     VecRegContainer(const std::vector<uint8_t>& that)
     {
         assert(that.size() >= SIZE);
         std::memcpy(container.data(), &that[0], SIZE);
     }

     /** Zero the container. */
     void zero() { memset(container.data(), 0, SIZE); }

     /** Assignment operators. */
     /** @{ */
     /** From VecRegContainer */
     MyClass& operator=(const MyClass& that)
     {
         if (&that == this)
             return *this;
         memcpy(container.data(), that.container.data(), SIZE);
         return *this;
     }

     /** From appropriately sized uint8_t[]. */
     MyClass& operator=(const Container& that)
     {
         std::memcpy(container.data(), that.data(), SIZE);
         return *this;
     }

     /** From vector<uint8_t>.
      * This is required for de-serialisation.
      * */
     MyClass& operator=(const std::vector<uint8_t>& that)
     {
         assert(that.size() >= SIZE);
         std::memcpy(container.data(), that.data(), SIZE);
         return *this;
     }
     /** @} */

     /** Copy the contents into the input buffer. */
     /** @{ */
     /** To appropriately sized uint8_t[] */
     void copyTo(Container& dst) const
     {
         std::memcpy(dst.data(), container.data(), SIZE);
     }

     /** To vector<uint8_t>
      * This is required for serialisation.
      * */
     void copyTo(std::vector<uint8_t>& dst) const
     {
         dst.resize(SIZE);
         std::memcpy(dst.data(), container.data(), SIZE);
     }
     /** @} */

     /** Equality operator.
      * Required to compare thread contexts.
      */
     template<size_t S2>
     inline bool
     operator==(const VecRegContainer<S2>& that) const
     {
         return SIZE == S2 &&
                !memcmp(container.data(), that.container.data(), SIZE);
     }
     /** Inequality operator.
      * Required to compare thread contexts.
      */
     template<size_t S2>
     bool
     operator!=(const VecRegContainer<S2>& that) const
     {
         return !operator==(that);
     }

     const std::string print() const { return csprintf("%s", *this); }
     /** Get pointer to bytes. */
     template <typename Ret>
     const Ret* raw_ptr() const { return (const Ret*)container.data(); }

     template <typename Ret>
     Ret* raw_ptr() { return (Ret*)container.data(); }

     /**
      * View interposers.
      * Create a view of this container as a vector of VecElems with an
      * optional amount of elements. If the amount of elements is provided,
      * the size of the container is checked, to test bounds. If it is not
      * provided, the length is inferred from the container size and the
      * element size.
      * @tparam VecElem Type of each element of the vector for the view.
      * @tparam NumElem Amount of elements in the view.
      */
     /** @{ */
     template <typename VecElem, size_t NumElems = SIZE/sizeof(VecElem)>
     VecRegT<VecElem, NumElems, true> as() const
     {
         static_assert(SIZE % sizeof(VecElem) == 0,
                 "VecElem does not evenly divide the register size");
         static_assert(sizeof(VecElem) * NumElems <= SIZE,
                 "Viewing VecReg as something bigger than it is");
         return VecRegT<VecElem, NumElems, true>(*this);
     }

     template <typename VecElem, size_t NumElems = SIZE/sizeof(VecElem)>
     VecRegT<VecElem, NumElems, false> as()
     {
         static_assert(SIZE % sizeof(VecElem) == 0,
                 "VecElem does not evenly divide the register size");
         static_assert(sizeof(VecElem) * NumElems <= SIZE,
                 "Viewing VecReg as something bigger than it is");
         return VecRegT<VecElem, NumElems, false>(*this);
     }

     template <typename VecElem, int LaneIdx>
     VecLaneT<VecElem, false> laneView();
     template <typename VecElem, int LaneIdx>
     VecLaneT<VecElem, true> laneView() const;
     template <typename VecElem>
     VecLaneT<VecElem, false> laneView(int laneIdx);
     template <typename VecElem>
     VecLaneT<VecElem, true> laneView(int laneIdx) const;
     /** @} */
     /**
      * Output operator.
      * Used for serialization.
      */
     friend std::ostream& operator<<(std::ostream& os, const MyClass& v)
     {
         for (auto& b: v.container) {
             os << csprintf("%02x", b);
         }
         return os;
     }
 };

 /** We define an auxiliary abstraction for LaneData. The ISA should care
  * about the semantics of a, e.g., 32bit element, treating it as a signed or
  * unsigned int, or a float depending on the semantics of a particular
  * instruction. On the other hand, the cpu model should only care about it
  * being a 32-bit value. */
 enum class LaneSize
 {
     Empty = 0,
     Byte,
     TwoByte,
     FourByte,
     EightByte,
 };

 /** LaneSize is an abstraction of a LS byte value for the execution and thread
  * contexts to handle values just depending on its width. That way, the ISA
  * can request, for example, the second 4 byte lane of register 5 to the model.
  * The model serves that value, agnostic of the semantics of those bits. Then,
  * it is up to the ISA to interpret those bits as a float, or as an uint.
  * To maximize the utility, this class implements the assignment operator and
  * the casting to equal-size types.
  * As opposed to a RegLaneT, LaneData is not 'backed' by a VecRegContainer.
  * The idea is:
  *  When data is passed and is susceptible to being copied, use LaneData, as
  *     copying the primitive type is build on is cheap.
  *  When data is passed as references (const or not), use RegLaneT, as all
  *     operations happen 'in place', avoiding any copies (no copies is always
  *     cheaper than cheap copies), especially when things are inlined, and
  *     references are not explicitly passed.
  */
 template <LaneSize LS>
 class LaneData
 {
   public:
     /** Alias to the native type of the appropriate size. */
     using UnderlyingType =
         typename std::conditional<LS == LaneSize::EightByte, uint64_t,
             typename std::conditional<LS == LaneSize::FourByte, uint32_t,
                 typename std::conditional<LS == LaneSize::TwoByte, uint16_t,
                     typename std::conditional<LS == LaneSize::Byte, uint8_t,
                     void>::type
                 >::type
             >::type
         >::type;
   private:
     static constexpr auto ByteSz = sizeof(UnderlyingType);
     UnderlyingType _val;
     using MyClass = LaneData<LS>;

   public:
     template <typename T> explicit
     LaneData(typename std::enable_if<sizeof(T) == ByteSz, const T&>::type t)
                 : _val(t) {}

     template <typename T>
     typename std::enable_if<sizeof(T) == ByteSz, MyClass&>::type
     operator=(const T& that)
     {
         _val = that;
         return *this;
     }
     template<typename T,
              typename std::enable_if<sizeof(T) == ByteSz, int>::type I = 0>
     operator T() const {
         return *static_cast<const T*>(&_val);
     }
 };

 /** Output operator overload for LaneData<Size>. */
 template <LaneSize LS>
 inline std::ostream&
 operator<<(std::ostream& os, const LaneData<LS>& d)
 {
     return os << static_cast<typename LaneData<LS>::UnderlyingType>(d);
 }

 /** Vector Lane abstraction
  * Another view of a container. This time only a partial part of it is exposed.
  * @tparam VecElem Type of each element of the vector.
  * @tparam Const Indicate if the underlying container can be modified through
  * the view.
  */
 /** @{ */
 /* General */
 template <typename VecElem, bool Const>
 class VecLaneT
 {
   public:
     /** VecRegContainer friendship to access private VecLaneT constructors.
      * Only VecRegContainers can build VecLanes.
      */
     /** @{ */
     friend VecLaneT<VecElem, !Const>;

     /*template <size_t Sz>
     friend class VecRegContainer;*/
     friend class VecRegContainer<8>;
     friend class VecRegContainer<16>;
     friend class VecRegContainer<32>;
     friend class VecRegContainer<64>;
     friend class VecRegContainer<128>;

     /** My type alias. */
     using MyClass = VecLaneT<VecElem, Const>;

   private:
     using Cont = typename std::conditional<Const,
                                               const VecElem,
                                               VecElem>::type;
     static_assert(!std::is_const<VecElem>::value || Const,
             "Asked for non-const lane of const type!");
     static_assert(std::is_integral<VecElem>::value,
             "VecElem type is not integral!");
     /** Reference to data. */
     Cont& container;

     /** Constructor */
     VecLaneT(Cont& cont) : container(cont) { }

   public:
     /** Assignment operators.
      * Assignment operators are only enabled if the underlying container is
      * non-constant.
      */
     /** @{ */
     template <bool Assignable = !Const>
     typename std::enable_if<Assignable, MyClass&>::type
     operator=(const VecElem& that) {
         container = that;
         return *this;
     }
     /**
      * Generic.
      * Generic bitwise assignment. Narrowing and widening assignemnts are
      * not allowed, pre-treatment of the rhs is required to conform.
      */
     template <bool Assignable = !Const, typename T>
     typename std::enable_if<Assignable, MyClass&>::type
     operator=(const T& that) {
         static_assert(sizeof(T) >= sizeof(VecElem),
                 "Attempt to perform widening bitwise copy.");
         static_assert(sizeof(T) <= sizeof(VecElem),
                 "Attempt to perform narrowing bitwise copy.");
         container = static_cast<VecElem>(that);
         return *this;
     }
     /** @} */
     /** Cast to vecElem. */
     operator VecElem() const { return container; }

     /** Constification. */
     template <bool Cond = !Const, typename std::enable_if<Cond, int>::type = 0>
     operator VecLaneT<typename std::enable_if<Cond, VecElem>::type, true>()
     {
         return VecLaneT<VecElem, true>(container);
     }
 };

 namespace std {
     template<typename T, bool Const>
     struct add_const<VecLaneT<T, Const>> { typedef VecLaneT<T, true> type; };
 }

 /** View as the Nth lane of type VecElem. */
 template <size_t Sz>
 template <typename VecElem, int LaneIdx>
 VecLaneT<VecElem, false>
 VecRegContainer<Sz>::laneView()
 {
     return VecLaneT<VecElem, false>(as<VecElem>()[LaneIdx]);
 }

 /** View as the const Nth lane of type VecElem. */
 template <size_t Sz>
 template <typename VecElem, int LaneIdx>
 VecLaneT<VecElem, true>
 VecRegContainer<Sz>::laneView() const
 {
     return VecLaneT<VecElem, true>(as<VecElem>()[LaneIdx]);
 }

 /** View as the Nth lane of type VecElem. */
 template <size_t Sz>
 template <typename VecElem>
 VecLaneT<VecElem, false>
 VecRegContainer<Sz>::laneView(int laneIdx)
 {
     return VecLaneT<VecElem, false>(as<VecElem>()[laneIdx]);
 }

 /** View as the const Nth lane of type VecElem. */
 template <size_t Sz>
 template <typename VecElem>
 VecLaneT<VecElem, true>
 VecRegContainer<Sz>::laneView(int laneIdx) const
 {
     return VecLaneT<VecElem, true>(as<VecElem>()[laneIdx]);
 }

 using VecLane8 = VecLaneT<uint8_t, false>;
 using VecLane16 = VecLaneT<uint16_t, false>;
 using VecLane32 = VecLaneT<uint32_t, false>;
 using VecLane64 = VecLaneT<uint64_t, false>;

 using ConstVecLane8 = VecLaneT<uint8_t, true>;
 using ConstVecLane16 = VecLaneT<uint16_t, true>;
 using ConstVecLane32 = VecLaneT<uint32_t, true>;
 using ConstVecLane64 = VecLaneT<uint64_t, true>;

 /**
  * Calls required for serialization/deserialization
  */
 /** @{ */
 template <size_t Sz>
 inline bool
 to_number(const std::string& value, VecRegContainer<Sz>& v)
 {
     int i = 0;
     while (i < Sz) {
         std::string byte = value.substr(i<<1, 2);
         v.template raw_ptr<uint8_t>()[i] = stoul(byte, 0, 16);
         i++;
     }
     return true;
 }
 /** @} */

 #endif /* __ARCH_GENERIC_VEC_REG_HH__ */
	/*
	* Copyright (c) 2015-2016 ARM Limited
	* All rights reserved
	*
	* The license below extends only to copyright in the software and shall
	* not be construed as granting a license to any other intellectual
	* property including but not limited to intellectual property relating
	* to a hardware implementation of the functionality of the software
	* licensed hereunder. You may use the software subject to the license
	* terms below provided that you ensure that this notice is replicated
	* unmodified and in its entirety in all distributions of the software,
	* modified or unmodified, in source code or in binary form.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions are
	* met: redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer;
	* redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution;
	* neither the name of the copyright holders nor the names of its
	* contributors may be used to endorse or promote products derived from
	* this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*
	* Authors: Giacomo Gabrielli
	* Nathanael Premillieu
	* Rekai Gonzalez
	*/

	/** \file arch/generic/vec_reg.hh
	* Vector Registers layout specification.
	*
	* This register type is to be used to model the SIMD registers.
	* It takes into account the possibility that different architectural names
	* may overlap (like for ARMv8 AArch32 for example).
	*
	* The design is having a basic vector register container that holds the
	* bytes, unaware of anything else. This is implemented by VecRegContainer.
	* As the (maximum) length of the physical vector register is a compile-time
	* constant, it is defined as a template parameter.
	*
	* This file also describes two views of the container that have semantic
	* information about the bytes. The first of this views is VecRegT.
	* A VecRegT is a view of a VecRegContainer (by reference). The VecRegT has
	* a type (VecElem) to which bytes are casted, and the amount of such
	* elements that the vector contains (NumElems). The size of a view,
	* calculated as sizeof(VecElem) * NumElems must match the size of the
	* underlying container. As VecRegT has some degree of type information it
	* has vector semantics, and defines the index operator ([]) to get
	* references to particular bytes understood as a VecElem.
	* The second view of a container implemented in this file is VecLaneT, which
	* is a view of a subset of the container.
	* A VecLaneT is a view of a lane of a vector register, where a lane is
	* identified by a type (VecElem) and an index (although the view is
	* unaware of its index). Operations on the lane are directly applied to
	* the corresponding bytes of the underlying VecRegContainer through a
	* reference.
	*
	* The intended usage is requesting views to the VecRegContainer via the
	* member 'as' for VecRegT and the member 'laneView' for VecLaneT. Kindly
	* find an example of usage in the following.
	*
	*
	* // We declare 512 bits vectors
	* using Vec512 = VecRegContainer<64>;
	* ...
	* // We implement the physical vector register file
	* Vec512 physicalVecRegFile[NUM_VREGS];
	* ...
	* // Usage example, for a macro op:
	* VecFloat8Add(ExecContext* xd) {
	* // Request source vector register to the execution context (const as it
	* // is read only).
	* const Vec512& vsrc1raw = xc->readVecRegOperand(this, 0);
	* // View it as a vector of floats (we could just specify the first
	* // template parametre, the second has a default value that works, and the
	* // last one is derived by the constness of vsrc1raw).
	* VecRegT<float, 8, true>& vsrc1 = vsrc1raw->as<float, 8>();
	*
	* // Second source and view
	* const Vec512& vsrc2raw = xc->readVecRegOperand(this, 1);
	* VecRegT<float, 8, true>& vsrc2 = vsrc2raw->as<float, 8>();
	*
	* // Destination and view
	* Vec512 vdstraw;
	* VecRegT<float, 8, false>& vdst = vdstraw->as<float, 8>();
	*
	* for (auto i = 0; i < 8; i++) {
	* // This asignment sets the bits in the underlying Vec512: vdstraw
	* vdst[i] = vsrc1[i] + vsrc2[i];
	* }
	* xc->setWriteRegOperand(this, 0, vdstraw);
	* }
	*
	* // Usage example, for a micro op that operates over lane number _lidx:
	* VecFloatLaneAdd(ExecContext* xd) {
	* // Request source vector register to the execution context (const as it
	* // is read only).
	* const Vec512& vsrc1raw = xc->readVecRegOperand(this, 0);
	* // View it as a lane of a vector of floats (we could just specify the
	* // first template parametre, the second is derived by the constness of
	* // vsrc1raw).
	* VecLaneT<float, true>& src1 = vsrc1raw->laneView<float>(this->_lidx);
	*
	* // Second source and view
	* const Vec512& vsrc2raw = xc->readVecRegOperand(this, 1);
	* VecLaneT<float, true>& src2 = vsrc2raw->laneView<float>(this->_lidx);
	*
	* // (Writable) destination and view
	* // As this is a partial write, we need the exec context to support that
	* // through, e.g., 'readVecRegOperandToWrite' returning a writable
	* // reference to the register
	* Vec512 vdstraw = xc->readVecRegOperandToWrite(this, 3);
	* VecLaneT<float, false>& dst = vdstraw->laneView<float>(this->_lidx);
	*
	* dst = src1 + src2;
	* // There is no need to copy the value back into the exec context, as
	* // the assignment to dst modifies the appropriate bytes in vdstraw which
	* // is in turn, a reference to the register in the cpu model.
	* // For operations that do conditional writeback, we can decouple the
	* // write by doing:
	* // auto tmp = src1 + src2;
	* // if (test) {
	* // dst = tmp; // do writeback
	* // } else {
	* // // do not do writeback
	* // }
	* }
	*
	*/

	#ifndef __ARCH_GENERIC_VEC_REG_HH__
	#define __ARCH_GENERIC_VEC_REG_HH__

	#include <array>
	#include <cassert>
	#include <iostream>
	#include <string>
	#include <type_traits>
	#include <vector>

	#include "base/cprintf.hh"
	#include "base/misc.hh"

	template <size_t Sz>
	class VecRegContainer;

	/** Vector Register Abstraction
	* This generic class is a view in a particularization of MVC, to vector
	* registers. There is a VecRegContainer that implements the model, and
	* contains the data. To that model we can interpose different instantiations
	* of VecRegT to view the container as a vector of NumElems elems of type
	* VecElem.
	* @tparam VecElem Type of each element of the vector.
	* @tparam NumElems Amount of components of the vector.
	* @tparam Const Indicate if the underlying container can be modified through
	* the view.
	*/
	template <typename VecElem, size_t NumElems, bool Const>
	class VecRegT
	{
	/** Size of the register in bytes. */
	static constexpr size_t SIZE = sizeof(VecElem) * NumElems;
	public:
	/** Container type alias. */
	using Container = typename std::conditional<Const,
	const VecRegContainer<SIZE>,
	VecRegContainer<SIZE>>::type;
	private:
	/** My type alias. */
	using MyClass = VecRegT<VecElem, NumElems, Const>;
	/** Reference to container. */
	Container& container;

	public:
	/** Constructor. */
	VecRegT(Container& cnt) : container(cnt) {};

	/** Zero the container. */
	template<bool Condition = !Const>
	typename std::enable_if<Condition, void>::type
	zero() { container.zero(); }

	template<bool Condition = !Const>
	typename std::enable_if<Condition, MyClass&>::type
	operator=(const MyClass& that)
	{
	container = that.container;
	return *this;
	}

	/** Index operator. */
	const VecElem& operator[](size_t idx) const
	{
	return container.template raw_ptr<VecElem>()[idx];
	}

	/** Index operator. */
	template<bool Condition = !Const>
	typename std::enable_if<Condition, VecElem&>::type
	operator[](size_t idx)
	{
	return container.template raw_ptr<VecElem>()[idx];
	}

	/** Equality operator.
	* Required to compare thread contexts.
	*/
	template<typename VE2, size_t NE2, bool C2>
	bool
	operator==(const VecRegT<VE2, NE2, C2>& that) const
	{
	return container == that.container;
	}
	/** Inequality operator.
	* Required to compare thread contexts.
	*/
	template<typename VE2, size_t NE2, bool C2>
	bool
	operator!=(const VecRegT<VE2, NE2, C2>& that) const
	{
	return !operator==(that);
	}

	/** Output stream operator. */
	friend std::ostream&
	operator<<(std::ostream& os, const MyClass& vr)
	{
	/* 0-sized is not allowed */
	os << "[" << std::hex << (uint32_t)vr[0];
	for (uint32_t e = 1; e < vr.SIZE; e++)
	os << " " << std::hex << (uint32_t)vr[e];
	os << ']';
	return os;
	}

	const std::string print() const { return csprintf("%s", *this); }
	/**
	* Cast to VecRegContainer&
	* It is useful to get the reference to the container for ISA tricks,
	* because casting to reference prevents unnecessary copies.
	*/
	operator Container&() { return container; }
	};

	/* Forward declaration. */
	template <typename VecElem, bool Const>
	class VecLaneT;

	/**
	* Vector Register Abstraction
	* This generic class is the model in a particularization of MVC, to vector
	* registers. The model has functionality to create views of itself, or a
	* portion through the method 'as
	* @tparam Sz Size of the container in bytes.
	*/
	template <size_t Sz>
	class VecRegContainer
	{
	static_assert(Sz > 0,
	"Cannot create Vector Register Container of zero size");
	public:
	static constexpr size_t SIZE = Sz;
	using Container = std::array<uint8_t,Sz>;
	private:
	Container container;
	using MyClass = VecRegContainer<SIZE>;

	public:
	VecRegContainer() {}
	/* This is required for de-serialisation. */
	VecRegContainer(const std::vector<uint8_t>& that)
	{
	assert(that.size() >= SIZE);
	std::memcpy(container.data(), &that[0], SIZE);
	}

	/** Zero the container. */
	void zero() { memset(container.data(), 0, SIZE); }

	/** Assignment operators. */
	/** @{ */
	/** From VecRegContainer */
	MyClass& operator=(const MyClass& that)
	{
	if (&that == this)
	return *this;
	memcpy(container.data(), that.container.data(), SIZE);
	return *this;
	}

	/** From appropriately sized uint8_t[]. */
	MyClass& operator=(const Container& that)
	{
	std::memcpy(container.data(), that.data(), SIZE);
	return *this;
	}

	/** From vector<uint8_t>.
	* This is required for de-serialisation.
	* */
	MyClass& operator=(const std::vector<uint8_t>& that)
	{
	assert(that.size() >= SIZE);
	std::memcpy(container.data(), that.data(), SIZE);
	return *this;
	}
	/** @} */

	/** Copy the contents into the input buffer. */
	/** @{ */
	/** To appropriately sized uint8_t[] */
	void copyTo(Container& dst) const
	{
	std::memcpy(dst.data(), container.data(), SIZE);
	}

	/** To vector<uint8_t>
	* This is required for serialisation.
	* */
	void copyTo(std::vector<uint8_t>& dst) const
	{
	dst.resize(SIZE);
	std::memcpy(dst.data(), container.data(), SIZE);
	}
	/** @} */

	/** Equality operator.
	* Required to compare thread contexts.
	*/
	template<size_t S2>
	inline bool
	operator==(const VecRegContainer<S2>& that) const
	{
	return SIZE == S2 &&
	!memcmp(container.data(), that.container.data(), SIZE);
	}
	/** Inequality operator.
	* Required to compare thread contexts.
	*/
	template<size_t S2>
	bool
	operator!=(const VecRegContainer<S2>& that) const
	{
	return !operator==(that);
	}

	const std::string print() const { return csprintf("%s", *this); }
	/** Get pointer to bytes. */
	template <typename Ret>
	const Ret* raw_ptr() const { return (const Ret*)container.data(); }

	template <typename Ret>
	Ret* raw_ptr() { return (Ret*)container.data(); }

	/**
	* View interposers.
	* Create a view of this container as a vector of VecElems with an
	* optional amount of elements. If the amount of elements is provided,
	* the size of the container is checked, to test bounds. If it is not
	* provided, the length is inferred from the container size and the
	* element size.
	* @tparam VecElem Type of each element of the vector for the view.
	* @tparam NumElem Amount of elements in the view.
	*/
	/** @{ */
	template <typename VecElem, size_t NumElems = SIZE/sizeof(VecElem)>
	VecRegT<VecElem, NumElems, true> as() const
	{
	static_assert(SIZE % sizeof(VecElem) == 0,
	"VecElem does not evenly divide the register size");
	static_assert(sizeof(VecElem) * NumElems <= SIZE,
	"Viewing VecReg as something bigger than it is");
	return VecRegT<VecElem, NumElems, true>(*this);
	}

	template <typename VecElem, size_t NumElems = SIZE/sizeof(VecElem)>
	VecRegT<VecElem, NumElems, false> as()
	{
	static_assert(SIZE % sizeof(VecElem) == 0,
	"VecElem does not evenly divide the register size");
	static_assert(sizeof(VecElem) * NumElems <= SIZE,
	"Viewing VecReg as something bigger than it is");
	return VecRegT<VecElem, NumElems, false>(*this);
	}

	template <typename VecElem, int LaneIdx>
	VecLaneT<VecElem, false> laneView();
	template <typename VecElem, int LaneIdx>
	VecLaneT<VecElem, true> laneView() const;
	template <typename VecElem>
	VecLaneT<VecElem, false> laneView(int laneIdx);
	template <typename VecElem>
	VecLaneT<VecElem, true> laneView(int laneIdx) const;
	/** @} */
	/**
	* Output operator.
	* Used for serialization.
	*/
	friend std::ostream& operator<<(std::ostream& os, const MyClass& v)
	{
	for (auto& b: v.container) {
	os << csprintf("%02x", b);
	}
	return os;
	}
	};

	/** We define an auxiliary abstraction for LaneData. The ISA should care
	* about the semantics of a, e.g., 32bit element, treating it as a signed or
	* unsigned int, or a float depending on the semantics of a particular
	* instruction. On the other hand, the cpu model should only care about it
	* being a 32-bit value. */
	enum class LaneSize
	{
	Empty = 0,
	Byte,
	TwoByte,
	FourByte,
	EightByte,
	};

	/** LaneSize is an abstraction of a LS byte value for the execution and thread
	* contexts to handle values just depending on its width. That way, the ISA
	* can request, for example, the second 4 byte lane of register 5 to the model.
	* The model serves that value, agnostic of the semantics of those bits. Then,
	* it is up to the ISA to interpret those bits as a float, or as an uint.
	* To maximize the utility, this class implements the assignment operator and
	* the casting to equal-size types.
	* As opposed to a RegLaneT, LaneData is not 'backed' by a VecRegContainer.
	* The idea is:
	* When data is passed and is susceptible to being copied, use LaneData, as
	* copying the primitive type is build on is cheap.
	* When data is passed as references (const or not), use RegLaneT, as all
	* operations happen 'in place', avoiding any copies (no copies is always
	* cheaper than cheap copies), especially when things are inlined, and
	* references are not explicitly passed.
	*/
	template <LaneSize LS>
	class LaneData
	{
	public:
	/** Alias to the native type of the appropriate size. */
	using UnderlyingType =
	typename std::conditional<LS == LaneSize::EightByte, uint64_t,
	typename std::conditional<LS == LaneSize::FourByte, uint32_t,
	typename std::conditional<LS == LaneSize::TwoByte, uint16_t,
	typename std::conditional<LS == LaneSize::Byte, uint8_t,
	void>::type
	>::type
	>::type
	>::type;
	private:
	static constexpr auto ByteSz = sizeof(UnderlyingType);
	UnderlyingType _val;
	using MyClass = LaneData<LS>;

	public:
	template <typename T> explicit
	LaneData(typename std::enable_if<sizeof(T) == ByteSz, const T&>::type t)
	: _val(t) {}

	template <typename T>
	typename std::enable_if<sizeof(T) == ByteSz, MyClass&>::type
	operator=(const T& that)
	{
	_val = that;
	return *this;
	}
	template<typename T,
	typename std::enable_if<sizeof(T) == ByteSz, int>::type I = 0>
	operator T() const {
	return static_cast<const T>(&_val);
	}
	};

	/** Output operator overload for LaneData<Size>. */
	template <LaneSize LS>
	inline std::ostream&
	operator<<(std::ostream& os, const LaneData<LS>& d)
	{
	return os << static_cast<typename LaneData<LS>::UnderlyingType>(d);
	}

	/** Vector Lane abstraction
	* Another view of a container. This time only a partial part of it is exposed.
	* @tparam VecElem Type of each element of the vector.
	* @tparam Const Indicate if the underlying container can be modified through
	* the view.
	*/
	/** @{ */
	/* General */
	template <typename VecElem, bool Const>
	class VecLaneT
	{
	public:
	/** VecRegContainer friendship to access private VecLaneT constructors.
	* Only VecRegContainers can build VecLanes.
	*/
	/** @{ */
	friend VecLaneT<VecElem, !Const>;

	/*template <size_t Sz>
	friend class VecRegContainer;*/
	friend class VecRegContainer<8>;
	friend class VecRegContainer<16>;
	friend class VecRegContainer<32>;
	friend class VecRegContainer<64>;
	friend class VecRegContainer<128>;

	/** My type alias. */
	using MyClass = VecLaneT<VecElem, Const>;

	private:
	using Cont = typename std::conditional<Const,
	const VecElem,
	VecElem>::type;
	static_assert(!std::is_const<VecElem>::value \|\| Const,
	"Asked for non-const lane of const type!");
	static_assert(std::is_integral<VecElem>::value,
	"VecElem type is not integral!");
	/** Reference to data. */
	Cont& container;

	/** Constructor */
	VecLaneT(Cont& cont) : container(cont) { }

	public:
	/** Assignment operators.
	* Assignment operators are only enabled if the underlying container is
	* non-constant.
	*/
	/** @{ */
	template <bool Assignable = !Const>
	typename std::enable_if<Assignable, MyClass&>::type
	operator=(const VecElem& that) {
	container = that;
	return *this;
	}
	/**
	* Generic.
	* Generic bitwise assignment. Narrowing and widening assignemnts are
	* not allowed, pre-treatment of the rhs is required to conform.
	*/
	template <bool Assignable = !Const, typename T>
	typename std::enable_if<Assignable, MyClass&>::type
	operator=(const T& that) {
	static_assert(sizeof(T) >= sizeof(VecElem),
	"Attempt to perform widening bitwise copy.");
	static_assert(sizeof(T) <= sizeof(VecElem),
	"Attempt to perform narrowing bitwise copy.");
	container = static_cast<VecElem>(that);
	return *this;
	}
	/** @} */
	/** Cast to vecElem. */
	operator VecElem() const { return container; }

	/** Constification. */
	template <bool Cond = !Const, typename std::enable_if<Cond, int>::type = 0>
	operator VecLaneT<typename std::enable_if<Cond, VecElem>::type, true>()
	{
	return VecLaneT<VecElem, true>(container);
	}
	};

	namespace std {
	template<typename T, bool Const>
	struct add_const<VecLaneT<T, Const>> { typedef VecLaneT<T, true> type; };
	}

	/** View as the Nth lane of type VecElem. */
	template <size_t Sz>
	template <typename VecElem, int LaneIdx>
	VecLaneT<VecElem, false>
	VecRegContainer<Sz>::laneView()
	{
	return VecLaneT<VecElem, false>(as<VecElem>()[LaneIdx]);
	}

	/** View as the const Nth lane of type VecElem. */
	template <size_t Sz>
	template <typename VecElem, int LaneIdx>
	VecLaneT<VecElem, true>
	VecRegContainer<Sz>::laneView() const
	{
	return VecLaneT<VecElem, true>(as<VecElem>()[LaneIdx]);
	}

	/** View as the Nth lane of type VecElem. */
	template <size_t Sz>
	template <typename VecElem>
	VecLaneT<VecElem, false>
	VecRegContainer<Sz>::laneView(int laneIdx)
	{
	return VecLaneT<VecElem, false>(as<VecElem>()[laneIdx]);
	}

	/** View as the const Nth lane of type VecElem. */
	template <size_t Sz>
	template <typename VecElem>
	VecLaneT<VecElem, true>
	VecRegContainer<Sz>::laneView(int laneIdx) const
	{
	return VecLaneT<VecElem, true>(as<VecElem>()[laneIdx]);
	}

	using VecLane8 = VecLaneT<uint8_t, false>;
	using VecLane16 = VecLaneT<uint16_t, false>;
	using VecLane32 = VecLaneT<uint32_t, false>;
	using VecLane64 = VecLaneT<uint64_t, false>;

	using ConstVecLane8 = VecLaneT<uint8_t, true>;
	using ConstVecLane16 = VecLaneT<uint16_t, true>;
	using ConstVecLane32 = VecLaneT<uint32_t, true>;
	using ConstVecLane64 = VecLaneT<uint64_t, true>;

	/**
	* Calls required for serialization/deserialization
	*/
	/** @{ */
	template <size_t Sz>
	inline bool
	to_number(const std::string& value, VecRegContainer<Sz>& v)
	{
	int i = 0;
	while (i < Sz) {
	std::string byte = value.substr(i<<1, 2);
	v.template raw_ptr<uint8_t>()[i] = stoul(byte, 0, 16);
	i++;
	}
	return true;
	}
	/** @} */

	#endif /* __ARCH_GENERIC_VEC_REG_HH__ */