diff options
author | Matthias Kretz <m.kretz@gsi.de> | 2021-01-28 21:04:03 +0100 |
---|---|---|
committer | Matthias Kretz <m.kretz@gsi.de> | 2021-06-25 17:32:13 +0200 |
commit | 74ebd1297e9cfa9f7d05bfcac5510d4968cc6ba8 (patch) | |
tree | 9bb7e817fc371c9c9faed3f16d5039828ee1e24f /libstdc++-v3/include/experimental | |
parent | 3c3474679419707710a899a03151cbe79a91c360 (diff) |
libstdc++: Make use of __builtin_bit_cast for simd
The __bit_cast function was a hack to achieve what __builtin_bit_cast
can do, therefore use __builtin_bit_cast if possible. However,
__builtin_bit_cast cannot be used to cast from/to fixed_size_simd, since
it isn't trivially copyable (in the language sense — in principle it
is). Therefore add __proposed::simd_bit_cast to enable the use case
required in the test framework.
Signed-off-by: Matthias Kretz <m.kretz@gsi.de>
libstdc++-v3/ChangeLog:
* include/experimental/bits/simd.h (__bit_cast): Implement via
__builtin_bit_cast #if available.
(__proposed::simd_bit_cast): Add overloads for simd and
simd_mask, which use __builtin_bit_cast (or __bit_cast #if not
available), which return an object of the requested type with
the same bits as the argument.
* include/experimental/bits/simd_math.h: Use simd_bit_cast
instead of __bit_cast to allow casts to fixed_size_simd.
(copysign): Remove branch that was only required if __bit_cast
cannot be constexpr.
* testsuite/experimental/simd/tests/bits/test_values.h: Switch
from __bit_cast to __proposed::simd_bit_cast since the former
will not cast fixed_size objects anymore.
Diffstat (limited to 'libstdc++-v3/include/experimental')
-rw-r--r-- | libstdc++-v3/include/experimental/bits/simd.h | 57 | ||||
-rw-r--r-- | libstdc++-v3/include/experimental/bits/simd_math.h | 37 |
2 files changed, 72 insertions, 22 deletions
diff --git a/libstdc++-v3/include/experimental/bits/simd.h b/libstdc++-v3/include/experimental/bits/simd.h index c396ebd3ee3..ed2645bebc8 100644 --- a/libstdc++-v3/include/experimental/bits/simd.h +++ b/libstdc++-v3/include/experimental/bits/simd.h @@ -1602,7 +1602,9 @@ template <typename _To, typename _From> _GLIBCXX_SIMD_INTRINSIC constexpr _To __bit_cast(const _From __x) { - // TODO: implement with / replace by __builtin_bit_cast ASAP +#if __has_builtin(__builtin_bit_cast) + return __builtin_bit_cast(_To, __x); +#else static_assert(sizeof(_To) == sizeof(_From)); constexpr bool __to_is_vectorizable = is_arithmetic_v<_To> || is_enum_v<_To>; @@ -1633,6 +1635,7 @@ template <typename _To, typename _From> reinterpret_cast<const char*>(&__x), sizeof(_To)); return __r; } +#endif } // }}} @@ -2904,6 +2907,58 @@ template <typename _Tp, typename _Up, typename _Ap, return {__private_init, _RM::abi_type::_MaskImpl::template _S_convert< typename _RM::simd_type::value_type>(__x)}; } + +template <typename _To, typename _Up, typename _Abi> + _GLIBCXX_SIMD_INTRINSIC _GLIBCXX_SIMD_CONSTEXPR + _To + simd_bit_cast(const simd<_Up, _Abi>& __x) + { + using _Tp = typename _To::value_type; + using _ToMember = typename _SimdTraits<_Tp, typename _To::abi_type>::_SimdMember; + using _From = simd<_Up, _Abi>; + using _FromMember = typename _SimdTraits<_Up, _Abi>::_SimdMember; + // with concepts, the following should be constraints + static_assert(sizeof(_To) == sizeof(_From)); + static_assert(is_trivially_copyable_v<_Tp> && is_trivially_copyable_v<_Up>); + static_assert(is_trivially_copyable_v<_ToMember> && is_trivially_copyable_v<_FromMember>); +#if __has_builtin(__builtin_bit_cast) + return {__private_init, __builtin_bit_cast(_ToMember, __data(__x))}; +#else + return {__private_init, __bit_cast<_ToMember>(__data(__x))}; +#endif + } + +template <typename _To, typename _Up, typename _Abi> + _GLIBCXX_SIMD_INTRINSIC _GLIBCXX_SIMD_CONSTEXPR + _To + simd_bit_cast(const simd_mask<_Up, _Abi>& __x) + { + using _From = simd_mask<_Up, _Abi>; + static_assert(sizeof(_To) == sizeof(_From)); + static_assert(is_trivially_copyable_v<_From>); + // _To can be simd<T, A>, specifically simd<T, fixed_size<N>> in which case _To is not trivially + // copyable. + if constexpr (is_simd_v<_To>) + { + using _Tp = typename _To::value_type; + using _ToMember = typename _SimdTraits<_Tp, typename _To::abi_type>::_SimdMember; + static_assert(is_trivially_copyable_v<_ToMember>); +#if __has_builtin(__builtin_bit_cast) + return {__private_init, __builtin_bit_cast(_ToMember, __x)}; +#else + return {__private_init, __bit_cast<_ToMember>(__x)}; +#endif + } + else + { + static_assert(is_trivially_copyable_v<_To>); +#if __has_builtin(__builtin_bit_cast) + return __builtin_bit_cast(_To, __x); +#else + return __bit_cast<_To>(__x); +#endif + } + } } // namespace __proposed // simd_cast {{{2 diff --git a/libstdc++-v3/include/experimental/bits/simd_math.h b/libstdc++-v3/include/experimental/bits/simd_math.h index dd9aaa35967..c81ad7cf08c 100644 --- a/libstdc++-v3/include/experimental/bits/simd_math.h +++ b/libstdc++-v3/include/experimental/bits/simd_math.h @@ -405,10 +405,11 @@ template <typename _Tp, typename _Abi> using _Vp = simd<_Tp, _Abi>; using _Up = make_unsigned_t<__int_for_sizeof_t<_Tp>>; using namespace std::experimental::__float_bitwise_operators; + using namespace std::experimental::__proposed; const _Vp __exponent_mask = __infinity_v<_Tp>; // 0x7f800000 or 0x7ff0000000000000 return static_simd_cast<rebind_simd_t<int, _Vp>>( - __bit_cast<rebind_simd_t<_Up, _Vp>>(__v & __exponent_mask) + simd_bit_cast<rebind_simd_t<_Up, _Vp>>(__v & __exponent_mask) >> (__digits_v<_Tp> - 1)); } @@ -697,11 +698,9 @@ template <typename _Tp, typename _Abi> // (inf and NaN are excluded by -ffinite-math-only) const auto __iszero_inf_nan = __x == 0; #else - const auto __as_int - = __bit_cast<rebind_simd_t<__int_for_sizeof_t<_Tp>, _V>>(abs(__x)); - const auto __inf - = __bit_cast<rebind_simd_t<__int_for_sizeof_t<_Tp>, _V>>( - _V(__infinity_v<_Tp>)); + using _Ip = __int_for_sizeof_t<_Tp>; + const auto __as_int = simd_bit_cast<rebind_simd_t<_Ip, _V>>(abs(__x)); + const auto __inf = simd_bit_cast<rebind_simd_t<_Ip, _V>>(_V(__infinity_v<_Tp>)); const auto __iszero_inf_nan = static_simd_cast<typename _V::mask_type>( __as_int == 0 || __as_int >= __inf); #endif @@ -719,10 +718,10 @@ template <typename _Tp, typename _Abi> where(__value_isnormal.__cvt(), __e) = __exponent_bits; static_assert(sizeof(_IV) == sizeof(__value_isnormal)); const _IV __offset - = (__bit_cast<_IV>(__value_isnormal) & _IV(__exp_adjust)) - | (__bit_cast<_IV>(static_simd_cast<_MaskType>(__exponent_bits == 0) - & static_simd_cast<_MaskType>(__x != 0)) - & _IV(__exp_adjust + __exp_offset)); + = (simd_bit_cast<_IV>(__value_isnormal) & _IV(__exp_adjust)) + | (simd_bit_cast<_IV>(static_simd_cast<_MaskType>(__exponent_bits == 0) + & static_simd_cast<_MaskType>(__x != 0)) + & _IV(__exp_adjust + __exp_offset)); *__exp = simd_cast<_Samesize<int, _V>>(__e - __offset); return __mant; } @@ -786,7 +785,7 @@ template <typename _Tp, typename _Abi> using namespace std::experimental::__proposed; using _IV = rebind_simd_t< conditional_t<sizeof(_Tp) == sizeof(_LLong), _LLong, int>, _V>; - return (__bit_cast<_IV>(__v) >> (__digits_v<_Tp> - 1)) + return (simd_bit_cast<_IV>(__v) >> (__digits_v<_Tp> - 1)) - (__max_exponent_v<_Tp> - 1); }; _V __r = static_simd_cast<_V>(__exponent(abs_x)); @@ -953,6 +952,7 @@ template <typename _VV> // Skylake-AVX512 (not even for SSE and AVX vectors, and really bad for // AVX-512). using namespace __float_bitwise_operators; + using namespace __proposed; _V __absx = abs(__x); // no error _V __absy = abs(__y); // no error _V __hi = max(__absx, __absy); // no error @@ -1000,9 +1000,9 @@ template <typename _VV> #ifdef __FAST_MATH__ using _Ip = __int_for_sizeof_t<_Tp>; using _IV = rebind_simd_t<_Ip, _V>; - const auto __as_int = __bit_cast<_IV>(__hi_exp); + const auto __as_int = simd_bit_cast<_IV>(__hi_exp); const _V __scale - = __bit_cast<_V>(2 * __bit_cast<_Ip>(_Tp(1)) - __as_int); + = simd_bit_cast<_V>(2 * simd_bit_cast<_Ip>(_Tp(1)) - __as_int); #else const _V __scale = (__hi_exp ^ __inf) * _Tp(.5); #endif @@ -1090,6 +1090,7 @@ _GLIBCXX_SIMD_CVTING2(hypot) else { using namespace __float_bitwise_operators; + using namespace __proposed; const _V __absx = abs(__x); // no error const _V __absy = abs(__y); // no error const _V __absz = abs(__z); // no error @@ -1169,9 +1170,9 @@ _GLIBCXX_SIMD_CVTING2(hypot) #ifdef __FAST_MATH__ using _Ip = __int_for_sizeof_t<_Tp>; using _IV = rebind_simd_t<_Ip, _V>; - const auto __as_int = __bit_cast<_IV>(__hi_exp); + const auto __as_int = simd_bit_cast<_IV>(__hi_exp); const _V __scale - = __bit_cast<_V>(2 * __bit_cast<_Ip>(_Tp(1)) - __as_int); + = simd_bit_cast<_V>(2 * simd_bit_cast<_Ip>(_Tp(1)) - __as_int); #else const _V __scale = (__hi_exp ^ __inf) * _Tp(.5); #endif @@ -1278,12 +1279,6 @@ template <typename _Tp, typename _Abi> return std::copysign(__x[0], __y[0]); else if constexpr (__is_fixed_size_abi_v<_Abi>) return {__private_init, _Abi::_SimdImpl::_S_copysign(__data(__x), __data(__y))}; - else if constexpr (is_same_v<_Tp, long double> && sizeof(_Tp) == 12) - // Remove this case once __bit_cast is implemented via __builtin_bit_cast. - // It is necessary, because __signmask below cannot be computed at compile - // time. - return simd<_Tp, _Abi>( - [&](auto __i) { return std::copysign(__x[__i], __y[__i]); }); else { using _V = simd<_Tp, _Abi>; |