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* [gcc r11-11428] libstdc++: Avoid vector casts while still avoiding PR90424
@ 2024-05-10 14:07 Matthias Kretz
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From: Matthias Kretz @ 2024-05-10 14:07 UTC (permalink / raw)
To: gcc-cvs, libstdc++-cvs
https://gcc.gnu.org/g:4190a95cb837c5d221d9c5677f49f3c7d4d5576f
commit r11-11428-g4190a95cb837c5d221d9c5677f49f3c7d4d5576f
Author: Matthias Kretz <m.kretz@gsi.de>
Date: Fri Jun 2 21:33:04 2023 +0200
libstdc++: Avoid vector casts while still avoiding PR90424
Signed-off-by: Matthias Kretz <m.kretz@gsi.de>
libstdc++-v3/ChangeLog:
PR libstdc++/109822
* include/experimental/bits/simd_builtin.h (_S_store): Rewrite
to avoid casts to other vector types. Implement store as
succession of power-of-2 sized memcpy to avoid PR90424.
(cherry picked from commit 9165ede56ababd6471e7a2ce4eab30f3d5129e14)
Diff:
---
.../include/experimental/bits/simd_builtin.h | 40 ++++++++--------------
1 file changed, 15 insertions(+), 25 deletions(-)
diff --git a/libstdc++-v3/include/experimental/bits/simd_builtin.h b/libstdc++-v3/include/experimental/bits/simd_builtin.h
index 9cdef60b85b2..9c8094d70167 100644
--- a/libstdc++-v3/include/experimental/bits/simd_builtin.h
+++ b/libstdc++-v3/include/experimental/bits/simd_builtin.h
@@ -1291,6 +1291,18 @@ struct _CommonImplBuiltin
// }}}
// _S_store {{{
+ template <size_t _Bytes>
+ _GLIBCXX_SIMD_INTRINSIC static void
+ _S_memcpy(char* __dst, const char* __src)
+ {
+ if constexpr (_Bytes > 0)
+ {
+ constexpr size_t _Ns = std::__bit_floor(_Bytes);
+ __builtin_memcpy(__dst, __src, _Ns);
+ _S_memcpy<_Bytes - _Ns>(__dst + _Ns, __src + _Ns);
+ }
+ }
+
template <size_t _ReqBytes = 0, typename _TV>
_GLIBCXX_SIMD_INTRINSIC static void
_S_store(_TV __x, void* __addr)
@@ -1298,33 +1310,11 @@ struct _CommonImplBuiltin
constexpr size_t _Bytes = _ReqBytes == 0 ? sizeof(__x) : _ReqBytes;
static_assert(sizeof(__x) >= _Bytes);
+#if !defined __clang__ && _GLIBCXX_SIMD_WORKAROUND_PR90424
if constexpr (__is_vector_type_v<_TV>)
- {
- using _Tp = typename _VectorTraits<_TV>::value_type;
- constexpr size_t _Np = _Bytes / sizeof(_Tp);
- static_assert(_Np * sizeof(_Tp) == _Bytes);
-
-#ifdef _GLIBCXX_SIMD_WORKAROUND_PR90424
- using _Up = conditional_t<
- (is_integral_v<_Tp> || _Bytes < 4),
- conditional_t<(sizeof(__x) > sizeof(long long)), long long, _Tp>,
- float>;
- const auto __v = __vector_bitcast<_Up>(__x);
-#else // _GLIBCXX_SIMD_WORKAROUND_PR90424
- const __vector_type_t<_Tp, _Np> __v = __x;
-#endif // _GLIBCXX_SIMD_WORKAROUND_PR90424
-
- if constexpr ((_Bytes & (_Bytes - 1)) != 0)
- {
- constexpr size_t _MoreBytes = std::__bit_ceil(_Bytes);
- alignas(decltype(__v)) char __tmp[_MoreBytes];
- __builtin_memcpy(__tmp, &__v, _MoreBytes);
- __builtin_memcpy(__addr, __tmp, _Bytes);
- }
- else
- __builtin_memcpy(__addr, &__v, _Bytes);
- }
+ _S_memcpy<_Bytes>(reinterpret_cast<char*>(__addr), reinterpret_cast<const char*>(&__x));
else
+#endif // _GLIBCXX_SIMD_WORKAROUND_PR90424
__builtin_memcpy(__addr, &__x, _Bytes);
}
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