[PATCH 02/16] Fix NEON intrinsic types usage

[Matthias Kretz]

From: Matthias Kretz <kretz@kde.org>

Intrinsics types for NEON differ from gnu::vector_size types now. This
requires explicit specializations for __intrinsic_type and a new
__is_intrinsic_type trait.

libstdc++-v3/ChangeLog:
	* include/experimental/bits/simd.h (__is_intrinsic_type): New
	internal type trait. Alias for __is_vector_type on x86.
	(_VectorTraitsImpl): Enable for __intrinsic_type in addition for
	__vector_type.
	(__intrin_bitcast): Allow casting to & from vector & intrinsic
	types.
	(__intrinsic_type): Explicitly specialize for NEON intrinsic
	vector types.
---
 libstdc++-v3/include/experimental/bits/simd.h | 70 +++++++++++++++++--
 1 file changed, 66 insertions(+), 4 deletions(-)

diff --git a/libstdc++-v3/include/experimental/bits/simd.h b/libstdc++-v3/
include/experimental/bits/simd.h
index 00eec50d64f..d56176210df 100644
--- a/libstdc++-v3/include/experimental/bits/simd.h
+++ b/libstdc++-v3/include/experimental/bits/simd.h
@@ -1379,13 +1379,35 @@ template <typename _Tp>
 template <typename _Tp>
   inline constexpr bool __is_vector_type_v = __is_vector_type<_Tp>::value;
 
+// }}}
+// __is_intrinsic_type {{{
+#if _GLIBCXX_SIMD_HAVE_SSE_ABI
+template <typename _Tp>
+  using __is_intrinsic_type = __is_vector_type<_Tp>;
+#else // not SSE (x86)
+template <typename _Tp, typename = void_t<>>
+  struct __is_intrinsic_type : false_type {};
+
+template <typename _Tp>
+  struct __is_intrinsic_type<
+    _Tp, void_t<typename __intrinsic_type<
+	   remove_reference_t<decltype(declval<_Tp>()[0])>, 
sizeof(_Tp)>::type>>
+    : is_same<_Tp, typename __intrinsic_type<
+		     remove_reference_t<decltype(declval<_Tp>()[0])>,
+		     sizeof(_Tp)>::type> {};
+#endif
+
+template <typename _Tp>
+  inline constexpr bool __is_intrinsic_type_v = 
__is_intrinsic_type<_Tp>::value;
+
 // }}}
 // _VectorTraits{{{
 template <typename _Tp, typename = void_t<>>
   struct _VectorTraitsImpl;
 
 template <typename _Tp>
-  struct _VectorTraitsImpl<_Tp, enable_if_t<__is_vector_type_v<_Tp>>>
+  struct _VectorTraitsImpl<_Tp, enable_if_t<__is_vector_type_v<_Tp>
+					      || __is_intrinsic_type_v<_Tp>>>
   {
     using type = _Tp;
     using value_type = remove_reference_t<decltype(declval<_Tp>()[0])>;
@@ -1457,7 +1479,8 @@ template <typename _To, typename _From>
   _GLIBCXX_SIMD_INTRINSIC constexpr _To
   __intrin_bitcast(_From __v)
   {
-    static_assert(__is_vector_type_v<_From> && __is_vector_type_v<_To>);
+    static_assert((__is_vector_type_v<_From> || __is_intrinsic_type_v<_From>)
+		    && (__is_vector_type_v<_To> || __is_intrinsic_type_v<_To>));
     if constexpr (sizeof(_To) == sizeof(_From))
       return reinterpret_cast<_To>(__v);
     else if constexpr (sizeof(_From) > sizeof(_To))
@@ -2183,16 +2206,55 @@ template <typename _Tp, size_t _Bytes>
 #endif // _GLIBCXX_SIMD_HAVE_SSE_ABI
 // __intrinsic_type (ARM){{{
 #if _GLIBCXX_SIMD_HAVE_NEON
+template <>
+  struct __intrinsic_type<float, 8, void>
+  { using type = float32x2_t; };
+
+template <>
+  struct __intrinsic_type<float, 16, void>
+  { using type = float32x4_t; };
+
+#if _GLIBCXX_SIMD_HAVE_NEON_A64
+template <>
+  struct __intrinsic_type<double, 8, void>
+  { using type = float64x1_t; };
+
+template <>
+  struct __intrinsic_type<double, 16, void>
+  { using type = float64x2_t; };
+#endif
+
+#define _GLIBCXX_SIMD_ARM_INTRIN(_Bits, _Np)                                   
\
+template <>                                                                    
\
+  struct __intrinsic_type<__int_with_sizeof_t<_Bits / 8>,                      
\
+			  _Np * _Bits / 8, void>                               \
+  { using type = int##_Bits##x##_Np##_t; };                                    
\
+template <>                                                                    
\
+  struct __intrinsic_type<make_unsigned_t<__int_with_sizeof_t<_Bits / 8>>,     
\
+			  _Np * _Bits / 8, void>                               \
+  { using type = uint##_Bits##x##_Np##_t; }
+_GLIBCXX_SIMD_ARM_INTRIN(8, 8);
+_GLIBCXX_SIMD_ARM_INTRIN(8, 16);
+_GLIBCXX_SIMD_ARM_INTRIN(16, 4);
+_GLIBCXX_SIMD_ARM_INTRIN(16, 8);
+_GLIBCXX_SIMD_ARM_INTRIN(32, 2);
+_GLIBCXX_SIMD_ARM_INTRIN(32, 4);
+_GLIBCXX_SIMD_ARM_INTRIN(64, 1);
+_GLIBCXX_SIMD_ARM_INTRIN(64, 2);
+#undef _GLIBCXX_SIMD_ARM_INTRIN
+
 template <typename _Tp, size_t _Bytes>
   struct __intrinsic_type<_Tp, _Bytes,
 			  enable_if_t<__is_vectorizable_v<_Tp> && _Bytes <= 16>>
   {
-    static constexpr int _S_VBytes = _Bytes <= 8 ? 8 : 16;
+    static constexpr int _SVecBytes = _Bytes <= 8 ? 8 : 16;
     using _Ip = __int_for_sizeof_t<_Tp>;
     using _Up = conditional_t<
       is_floating_point_v<_Tp>, _Tp,
       conditional_t<is_unsigned_v<_Tp>, make_unsigned_t<_Ip>, _Ip>>;
-    using type [[__gnu__::__vector_size__(_S_VBytes)]] = _Up;
+    static_assert(!is_same_v<_Tp, _Up> || _SVecBytes != _Bytes,
+		  "should use explicit specialization above");
+    using type = typename __intrinsic_type<_Up, _SVecBytes>::type;
   };
 #endif // _GLIBCXX_SIMD_HAVE_NEON
 
-- 
──────────────────────────────────────────────────────────────────────────
 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
──────────────────────────────────────────────────────────────────────────