libstdc++: Add masked ++/-- implementation for sizeof < 16

This resolves further failures (-Wreturn-type warnings) and test
failures for where-* tests targeting AVX-512.

Signed-off-by: Matthias Kretz <m.kretz@gsi.de>
libstdc++-v3/ChangeLog:

	* include/experimental/bits/simd_x86.h (_S_masked_unary):
	Cast inputs < 16 bytes to 16 byte vectors before calling the
	right subtraction builtin. Before returning, truncate to the
	return vector type.

(cherry picked from commit a6c630c314b099f64d79055964d88b257459cf13)

diff --git a/libstdc++-v3/include/experimental/bits/simd_x86.h b/libstdc++-v3/include/experimental/bits/simd_x86.h
index fb0d6977832ae7618f5db8b8f85256251f9bdbd7..6883ab83f9628af94d135aba2d09a1b8b0e01554 100644 (file)
--- a/libstdc++-v3/include/experimental/bits/simd_x86.h
+++ b/libstdc++-v3/include/experimental/bits/simd_x86.h
@@ -3507,6 +3507,9 @@ template <typename _Abi>
 #ifdef __clang__
            return __movm<_Np, _Tp>(__k._M_data) ? __v._M_data - __pm_one : __v._M_data;
 #else // __clang__
+           using _TV = __vector_type_t<_Tp, _Np>;
+           constexpr size_t __bytes = sizeof(__v) < 16 ? 16 : sizeof(__v);
+           constexpr size_t __width = __bytes / sizeof(_Tp);
            if constexpr (is_integral_v<_Tp>)
              {
                constexpr bool __lp64 = sizeof(long) == sizeof(long long);
@@ -3516,11 +3519,11 @@ template <typename _Abi>
                              std::conditional_t<__lp64, long long, int>,
                              std::conditional_t<
                                std::is_same_v<_Ip, signed char>, char, _Ip>>;
-               const auto __value = __vector_bitcast<_Up>(__v._M_data);
+               const auto __value = __intrin_bitcast<__vector_type_t<_Up, __width>>(__v._M_data);
 #define _GLIBCXX_SIMD_MASK_SUB(_Sizeof, _Width, _Instr)                        \
-  if constexpr (sizeof(_Tp) == _Sizeof && sizeof(__v) == _Width)               \
-    return __vector_bitcast<_Tp>(__builtin_ia32_##_Instr##_mask(__value,       \
-            __vector_broadcast<_Np>(_Up(__pm_one)), __value, __k._M_data))
+  if constexpr (sizeof(_Tp) == _Sizeof && sizeof(__value) == _Width)           \
+    return __intrin_bitcast<_TV>(__builtin_ia32_##_Instr##_mask(__value,       \
+            __vector_broadcast<__width>(_Up(__pm_one)), __value, __k._M_data))
                _GLIBCXX_SIMD_MASK_SUB(1, 64, psubb512);
                _GLIBCXX_SIMD_MASK_SUB(1, 32, psubb256);
                _GLIBCXX_SIMD_MASK_SUB(1, 16, psubb128);
@@ -3537,16 +3540,17 @@ template <typename _Abi>
              }
            else
              {
+               const auto __value = __intrin_bitcast<__vector_type_t<_Tp, __width>>(__v._M_data);
 #define _GLIBCXX_SIMD_MASK_SUB_512(_Sizeof, _Width, _Instr)                    \
-  if constexpr (sizeof(_Tp) == _Sizeof && sizeof(__v) == _Width)               \
+  if constexpr (sizeof(_Tp) == _Sizeof && sizeof(__value) == _Width)           \
     return __builtin_ia32_##_Instr##_mask(                                     \
-            __v._M_data, __vector_broadcast<_Np>(_Tp(__pm_one)), __v._M_data, \
+            __value, __vector_broadcast<__width>(_Tp(__pm_one)), __value,     \
             __k._M_data, _MM_FROUND_CUR_DIRECTION)
 #define _GLIBCXX_SIMD_MASK_SUB(_Sizeof, _Width, _Instr)                        \
-  if constexpr (sizeof(_Tp) == _Sizeof && sizeof(__v) == _Width)               \
-    return __builtin_ia32_##_Instr##_mask(                                     \
-            __v._M_data, __vector_broadcast<_Np>(_Tp(__pm_one)), __v._M_data, \
-            __k._M_data)
+  if constexpr (sizeof(_Tp) == _Sizeof && sizeof(__value) == _Width)           \
+    return __intrin_bitcast<_TV>(__builtin_ia32_##_Instr##_mask(               \
+            __value, __vector_broadcast<__width>(_Tp(__pm_one)), __value,     \
+            __k._M_data))
                _GLIBCXX_SIMD_MASK_SUB_512(4, 64, subps512);
                _GLIBCXX_SIMD_MASK_SUB(4, 32, subps256);
                _GLIBCXX_SIMD_MASK_SUB(4, 16, subps128);