From: Matthias Kretz <kr...@kde.org>
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.kr...@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.
* 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.
---
libstdc++-v3/include/experimental/bits/simd.h | 40 ++++++++++++++++++-
.../include/experimental/bits/simd_math.h | 8 ++--
.../simd/tests/bits/test_values.h | 8 ++--
3 files changed, 46 insertions(+), 10 deletions(-)
--
──────────────────────────────────────────────────────────────────────────
Dr. Matthias Kretz https://mattkretz.github.io
GSI Helmholtz Centre for Heavy Ion Research https://gsi.de
std::experimental::simd https://github.com/VcDevel/std-simd
──────────────────────────────────────────────────────────────────────────diff --git a/libstdc++-v3/include/experimental/bits/simd.h b/libstdc++-v3/include/experimental/bits/simd.h
index 163f1b574e2..5d243f22434 100644
--- a/libstdc++-v3/include/experimental/bits/simd.h
+++ b/libstdc++-v3/include/experimental/bits/simd.h
@@ -1598,7 +1598,9 @@ 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>;
@@ -1629,6 +1631,7 @@ template <typename _To, typename _From>
reinterpret_cast<const char*>(&__x), sizeof(_To));
return __r;
}
+#endif
}
// }}}
@@ -2900,6 +2903,41 @@ 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<_To> && is_trivially_copyable_v<_From>);
+#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 d954e761eee..3ade293fcbf 100644
--- a/libstdc++-v3/include/experimental/bits/simd_math.h
+++ b/libstdc++-v3/include/experimental/bits/simd_math.h
@@ -700,11 +700,9 @@ 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
diff --git a/libstdc++-v3/testsuite/experimental/simd/tests/bits/test_values.h b/libstdc++-v3/testsuite/experimental/simd/tests/bits/test_values.h
index b69bd0b704d..67aa870659b 100644
--- a/libstdc++-v3/testsuite/experimental/simd/tests/bits/test_values.h
+++ b/libstdc++-v3/testsuite/experimental/simd/tests/bits/test_values.h
@@ -221,11 +221,11 @@ template <class V>
if constexpr (sizeof(T) <= sizeof(double))
{
using I = rebind_simd_t<__int_for_sizeof_t<T>, V>;
- const I abs_x = __bit_cast<I>(abs(x));
- const I min = __bit_cast<I>(V(std::__norm_min_v<T>));
- const I max = __bit_cast<I>(V(std::__finite_max_v<T>));
+ const I abs_x = simd_bit_cast<I>(abs(x));
+ const I min = simd_bit_cast<I>(V(std::__norm_min_v<T>));
+ const I max = simd_bit_cast<I>(V(std::__finite_max_v<T>));
return static_simd_cast<typename V::mask_type>(
- __bit_cast<I>(x) == 0 || (abs_x >= min && abs_x <= max));
+ simd_bit_cast<I>(x) == 0 || (abs_x >= min && abs_x <= max));
}
else
{
