reg_class.hh

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#ifndef __CPU__REG_CLASS_HH__
#define __CPU__REG_CLASS_HH__
 
#include <cstddef>
#include <iterator>
#include <string>
 
#include "arch/generic/vec_reg.hh"
#include "base/cprintf.hh"
#include "base/debug.hh"
#include "base/intmath.hh"
#include "base/types.hh"
#include "debug/InvalidReg.hh"
 
namespace gem5
{

enum RegClassType
{
    IntRegClass,        
    FloatRegClass,      
    VecRegClass,
    VecElemClass,
    VecPredRegClass,
    MatRegClass,        
    CCRegClass,         
    MiscRegClass,       
    InvalidRegClass = -1
};
 
// "Standard" register class names. Using these is encouraged but optional.
inline constexpr char IntRegClassName[] = "integer";
inline constexpr char FloatRegClassName[] = "floating_point";
inline constexpr char VecRegClassName[] = "vector";
inline constexpr char VecElemClassName[] = "vector_element";
inline constexpr char VecPredRegClassName[] = "vector_predicate";
inline constexpr char MatRegClassName[] = "matrix";
inline constexpr char CCRegClassName[] = "condition_code";
inline constexpr char MiscRegClassName[] = "miscellaneous";
 
class RegClass;
class RegClassIterator;
class BaseISA;

class RegId
{
  protected:
    const RegClass *_regClass = nullptr;
    RegIndex regIdx;
    int numPinnedWrites;
 
    friend struct std::hash<RegId>;
    friend class RegClassIterator;
 
  public:
    inline constexpr RegId();
 
    constexpr RegId(const RegClass &reg_class, RegIndex reg_idx)
        : _regClass(&reg_class), regIdx(reg_idx), numPinnedWrites(0)
    {}
 
    constexpr operator RegIndex() const
    {
        return index();
    }
 
    constexpr bool
    operator==(const RegId& that) const
    {
        return classValue() == that.classValue() && regIdx == that.index();
    }
 
    constexpr bool
    operator!=(const RegId& that) const
    {
        return !(*this==that);
    }

    constexpr bool
    operator<(const RegId& that) const
    {
        return classValue() < that.classValue() ||
            (classValue() == that.classValue() && (regIdx < that.index()));
    }

    constexpr bool
    isRenameable() const
    {
        return classValue() != MiscRegClass && classValue() != InvalidRegClass;
    }

    inline constexpr bool is(RegClassType reg_class) const;

    constexpr RegIndex index() const { return regIdx; }

    constexpr const RegClass &regClass() const { return *_regClass; }
    inline constexpr RegClassType classValue() const;
    inline constexpr const char* className() const;
 
    inline constexpr bool isFlat() const;
    inline RegId flatten(const BaseISA &isa) const;
 
    int getNumPinnedWrites() const { return numPinnedWrites; }
    void setNumPinnedWrites(int num_writes) { numPinnedWrites = num_writes; }
 
    friend inline std::ostream& operator<<(std::ostream& os, const RegId& rid);
};
 
class RegClassOps
{
  public:
    virtual ~RegClassOps() = default;
    virtual std::string regName(const RegId &id) const;
    virtual std::string valString(const void *val, const size_t& size) const;
    virtual RegId
    flatten(const BaseISA &isa, const RegId &id) const
    {
        return id;
    }
};
 
class RegClassIterator;
 
class RegClass
{
  private:
    RegClassType _type;
    const char *_name;
 
    size_t _numRegs;
    size_t _regBytes = sizeof(RegVal);
    // This is how much to shift an index by to get an offset of a register in
    // a register file from the register index, which would otherwise need to
    // be calculated with a multiply.
    size_t _regShift = ceilLog2(sizeof(RegVal));
 
    static inline RegClassOps defaultOps;
    const RegClassOps *_ops = &defaultOps;
    const debug::Flag &debugFlag;
 
    bool _flat = true;
 
  public:
    constexpr RegClass(RegClassType type, const char *new_name,
            size_t num_regs, const debug::Flag &debug_flag) :
        _type(type), _name(new_name), _numRegs(num_regs), debugFlag(debug_flag)
    {}
 
    constexpr RegClass
    needsFlattening() const
    {
        RegClass reg_class = *this;
        reg_class._flat = false;
        return reg_class;
    }
 
    constexpr RegClass
    ops(const RegClassOps &new_ops) const
    {
        RegClass reg_class = *this;
        reg_class._ops = &new_ops;
        return reg_class;
    }
 
    template <class RegType>
    constexpr RegClass
    regType() const
    {
        RegClass reg_class = *this;
        reg_class._regBytes = sizeof(RegType);
        reg_class._regShift = ceilLog2(reg_class._regBytes);
        return reg_class;
    }
 
    constexpr RegClassType type() const { return _type; }
    constexpr const char *name() const { return _name; }
    constexpr size_t numRegs() const { return _numRegs; }
    constexpr size_t regBytes() const { return _regBytes; }
    constexpr size_t regShift() const { return _regShift; }
    constexpr const debug::Flag &debug() const { return debugFlag; }
    constexpr bool isFlat() const { return _flat; }
 
    std::string regName(const RegId &id) const { return _ops->regName(id); }
    std::string
    valString(const void *val) const
    {
        return _ops->valString(val, regBytes());
    }
    std::string
    valString(const void *val, const size_t& num_bytes) const
    {
        return _ops->valString(val, std::min(regBytes(), num_bytes));
    }
    RegId
    flatten(const BaseISA &isa, const RegId &id) const
    {
        return isFlat() ? id : _ops->flatten(isa, id);
    }
 
    using iterator = RegClassIterator;
 
    inline iterator begin() const;
    inline iterator end() const;
 
    inline constexpr RegId operator[](RegIndex idx) const;
};
 
inline constexpr RegClass
    invalidRegClass(InvalidRegClass, "invalid", 0, debug::InvalidReg);
 
constexpr RegId::RegId() : RegId(invalidRegClass, 0) {}
 
constexpr bool
RegId::is(RegClassType reg_class) const
{
    return _regClass->type() == reg_class;
}
 
constexpr RegClassType RegId::classValue() const { return _regClass->type(); }
constexpr const char* RegId::className() const { return _regClass->name(); }
 
constexpr bool RegId::isFlat() const { return _regClass->isFlat(); }
RegId
RegId::flatten(const BaseISA &isa) const
{
    return _regClass->flatten(isa, *this);
}
 
std::ostream&
operator<<(std::ostream& os, const RegId& rid)
{
    return os << rid.regClass().regName(rid);
}
 
class RegClassIterator
{
  private:
    RegId id;
 
    RegClassIterator(const RegClass &reg_class, RegIndex idx) :
        id(reg_class, idx)
    {}
 
    friend class RegClass;
 
  public:
    using iterator_category = std::forward_iterator_tag;
    using difference_type = std::size_t;
    using value_type = const RegId;
    using pointer = value_type *;
    using reference = value_type &;
 
    reference operator*() const { return id; }
    pointer operator->() { return &id; }
 
    RegClassIterator &
    operator++()
    {
        id.regIdx++;
        return *this;
    }
 
    RegClassIterator
    operator++(int)
    {
        auto tmp = *this;
        ++(*this);
        return tmp;
    }
 
    bool
    operator==(const RegClassIterator &other) const
    {
        return id == other.id;
    }
 
    bool
    operator!=(const RegClassIterator &other) const
    {
        return id != other.id;
    }
};
 
RegClassIterator
RegClass::begin() const
{
    return RegClassIterator(*this, 0);
}
 
RegClassIterator
RegClass::end() const
{
    return RegClassIterator(*this, numRegs());
}
 
constexpr RegId
RegClass::operator[](RegIndex idx) const
{
    return RegId(*this, idx);
}
 
// Type matching for gem5::VecRegContainer class
// This is used in TypedRegClassOps.
template<typename>
struct is_vec_reg_container : std::false_type {};
template<std::size_t SIZE>
struct is_vec_reg_container<gem5::VecRegContainer<SIZE>> : std::true_type {};
 
template <typename ValueType>
class TypedRegClassOps : public RegClassOps
{
  public:
    std::string
    valString(const void *val, const size_t& size) const override
    {
        if constexpr (is_vec_reg_container<ValueType>::value) {
            if (size == sizeof(ValueType)) {
                return csprintf("%s", *(const ValueType *)val);
            } else {
                return ((const ValueType *)val)->getString(size);
            }
        } else {
            assert(size == sizeof(ValueType));
            return csprintf("%s", *(const ValueType *)val);
        }
    }
};
 
template <typename ValueType>
class VecElemRegClassOps : public TypedRegClassOps<ValueType>
{
  protected:
    size_t elemsPerVec;
 
  public:
    explicit VecElemRegClassOps(size_t elems_per_vec) :
        elemsPerVec(elems_per_vec)
    {}
 
    std::string
    regName(const RegId &id) const override
    {
        RegIndex reg_idx = id.index() / elemsPerVec;
        RegIndex elem_idx = id.index() % elemsPerVec;
        return csprintf("v%d[%d]", reg_idx, elem_idx);
    }
};

class PhysRegId : private RegId
{
  private:
    RegIndex flatIdx;
    int numPinnedWritesToComplete;
    bool pinned;
 
  public:
    explicit PhysRegId() : RegId(invalidRegClass, -1), flatIdx(-1),
                           numPinnedWritesToComplete(0)
    {}

    explicit PhysRegId(const RegClass &reg_class, RegIndex _regIdx,
              RegIndex _flatIdx)
        : RegId(reg_class, _regIdx), flatIdx(_flatIdx),
          numPinnedWritesToComplete(0), pinned(false)
    {}

    using RegId::index;
    using RegId::regClass;
    using RegId::classValue;
    using RegId::className;
    using RegId::is;
    bool
    operator<(const PhysRegId& that) const
    {
        return RegId::operator<(that);
    }
 
    bool
    operator==(const PhysRegId& that) const
    {
        return RegId::operator==(that);
    }
 
    bool
    operator!=(const PhysRegId& that) const
    {
        return RegId::operator!=(that);
    }


    bool isFixedMapping() const { return !isRenameable(); }

    const RegIndex& flatIndex() const { return flatIdx; }
 
    int getNumPinnedWrites() const { return numPinnedWrites; }
 
    void
    setNumPinnedWrites(int numWrites)
    {
        // An instruction with a pinned destination reg can get
        // squashed. The numPinnedWrites counter may be zero when
        // the squash happens but we need to know if the dest reg
        // was pinned originally in order to reset counters properly
        // for a possible re-rename using the same physical reg (which
        // may be required in case of a mem access order violation).
        pinned = (numWrites != 0);
        numPinnedWrites = numWrites;
    }
 
    void decrNumPinnedWrites() { --numPinnedWrites; }
    void incrNumPinnedWrites() { ++numPinnedWrites; }
 
    bool isPinned() const { return pinned; }
 
    int
    getNumPinnedWritesToComplete() const
    {
        return numPinnedWritesToComplete;
    }
 
    void
    setNumPinnedWritesToComplete(int numWrites)
    {
        numPinnedWritesToComplete = numWrites;
    }
 
    void decrNumPinnedWritesToComplete() { --numPinnedWritesToComplete; }
    void incrNumPinnedWritesToComplete() { ++numPinnedWritesToComplete; }
};
 
using PhysRegIdPtr = PhysRegId*;
 
} // namespace gem5
 
namespace std
{
template<>
struct hash<gem5::RegId>
{
    size_t
    operator()(const gem5::RegId& reg_id) const
    {
        // Extract unique integral values for the effective fields of a RegId.
        const size_t index = static_cast<size_t>(reg_id.index());
        const size_t class_num = static_cast<size_t>(reg_id.classValue());
 
        const size_t shifted_class_num =
            class_num << (sizeof(gem5::RegIndex) << 3);
 
        // Concatenate the class_num to the end of the flat_index, in order to
        // maximize information retained.
        const size_t concatenated_hash = index | shifted_class_num;
 
        // If RegIndex is larger than size_t, then class_num will not be
        // considered by this hash function, so we may wish to perform a
        // different operation to include that information in the hash.
        static_assert(sizeof(gem5::RegIndex) < sizeof(size_t),
            "sizeof(RegIndex) should be less than sizeof(size_t)");
 
        return concatenated_hash;
    }
};
} // namespace std
 
#endif // __CPU__REG_CLASS_HH__