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common/bit_field: Make BitField trivially copyable

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This makes the class much more flexible and doesn't make performing
copies with classes that contain a bitfield member a pain.

Given BitField instances are only intended to be used within unions, the
fact the full storage value would be copied isn't a big concern (only
sizeof(union_type) would be copied anyways).

While we're at it, provide defaulted move constructors for consistency.
This commit is contained in:
Lioncash 2019-03-07 16:32:10 -05:00
parent 3b63a46ca4
commit e99a148628
1 changed files with 7 additions and 9 deletions
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16
src/common/bit_field.h
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@ -111,12 +111,6 @@
template <std::size_t Position, std::size_t Bits, typename T> template <std::size_t Position, std::size_t Bits, typename T>
struct BitField { struct BitField {
private: private:
// We hide the copy assigment operator here, because the default copy
// assignment would copy the full storage value, rather than just the bits
// relevant to this particular bit field.
// We don't delete it because we want BitField to be trivially copyable.
constexpr BitField& operator=(const BitField&) = default;
// UnderlyingType is T for non-enum types and the underlying type of T if // UnderlyingType is T for non-enum types and the underlying type of T if
// T is an enumeration. Note that T is wrapped within an enable_if in the // T is an enumeration. Note that T is wrapped within an enable_if in the
// former case to workaround compile errors which arise when using // former case to workaround compile errors which arise when using
@ -163,9 +157,13 @@ public:
BitField(T val) = delete; BitField(T val) = delete;
BitField& operator=(T val) = delete; BitField& operator=(T val) = delete;
// Force default constructor to be created constexpr BitField() noexcept = default;
// so that we can use this within unions
constexpr BitField() = default; constexpr BitField(const BitField&) noexcept = default;
constexpr BitField& operator=(const BitField&) noexcept = default;
constexpr BitField(BitField&&) noexcept = default;
constexpr BitField& operator=(BitField&&) noexcept = default;
constexpr FORCE_INLINE operator T() const { constexpr FORCE_INLINE operator T() const {
return Value(); return Value();