inst_res.hh

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#ifndef __CPU_INST_RES_HH__
#define __CPU_INST_RES_HH__
 
#include <any>
#include <type_traits>
 
#include "base/logging.hh"
#include "base/types.hh"
 
namespace gem5
{
 
class InstResult
{
  private:
    std::any result;
    std::function<bool(const std::any &a, const std::any &b)> equals;
 
  public:
    InstResult() :
        // This InstResult is empty, and will only equal other InstResults
        // which are also empty.
        equals([](const std::any &a, const std::any &b) -> bool {
            gem5_assert(!a.has_value());
            return !b.has_value();
        })
    {}
    InstResult(const InstResult &) = default;
 
    template <typename T>
    explicit InstResult(T val) : result(val),
 
        // Set equals so it knows how to compare results of type T.
        equals([](const std::any &a, const std::any &b) -> bool {
            // If one has a value but the other doesn't, not equal.
            if (a.has_value() != b.has_value())
                return false;
            // If they are both empty, equal.
            if (!a.has_value())
                return true;
            // At least the local object should be of the right type.
            gem5_assert(a.type() == typeid(T));
            // If these aren't the same type, not equal.
            if (a.type() != b.type())
                return false;
            // We now know these both hold a result of the right type.
            return std::any_cast<const T&>(a) == std::any_cast<const T&>(b);
        })
    {
        static_assert(!std::is_pointer_v<T>,
                "InstResult shouldn't point to external data.");
        // Floating point values should be converted to/from ints using
        // floatToBits and bitsToFloat, and not stored in InstResult directly.
        static_assert(!std::is_floating_point_v<T>,
                "Floating point values should be converted to/from ints.");
    }
 
    // Convert floating point values to integers.
    template <typename T,
             std::enable_if_t<std::is_floating_point_v<T>, int> = 0>
    explicit InstResult(T val) : InstResult(floatToBits(val)) {}
 
    // Convert all integer types to RegVal.
    template <typename T,
        std::enable_if_t<std::is_integral_v<T> && !std::is_same_v<T, RegVal>,
                         int> = 0>
    explicit InstResult(T val) : InstResult(static_cast<RegVal>(val)) {}
 
    InstResult &
    operator=(const InstResult& that)
    {
        result = that.result;
        equals = that.equals;
        return *this;
    }
 
    bool
    operator==(const InstResult& that) const
    {
        return equals(result, that.result);
    }
 
    bool
    operator!=(const InstResult& that) const
    {
        return !operator==(that);
    }
 
    template <typename T>
    bool
    is() const
    {
        static_assert(!std::is_floating_point_v<T>,
                "Floating point values should be converted to/from ints.");
        return result.type() == typeid(T);
    }
 
    template <typename T>
    std::enable_if_t<std::is_integral_v<T> && !std::is_same_v<T, RegVal>, bool>
    is() const
    {
        return is<RegVal>();
    }
 
    bool isValid() const { return result.has_value(); }
    template <typename T>
    T
    as() const
    {
        assert(is<T>());
        return std::any_cast<T>(result);
    }
 
    template <typename T>
    std::enable_if_t<std::is_integral_v<T> && !std::is_same_v<T, RegVal>,
                     RegVal>
    as() const
    {
        return as<RegVal>();
    }
 
    template <typename T>
    T
    asNoAssert() const
    {
        if (!is<T>())
            return T{};
        return as<T>();
    }
 
};
 
} // namespace gem5
 
#endif // __CPU_INST_RES_HH__