[gcc r11-9990] libstdc++: ppc: conditionalize vsx-only simd intrinsics

[Alexandre Oliva <aoliva@gcc.gnu.org>]

https://gcc.gnu.org/g:9151de4b43bfb48202ee815924738197ac6e76a3

commit r11-9990-g9151de4b43bfb48202ee815924738197ac6e76a3
Author: Alexandre Oliva <oliva@adacore.com>
Date:   Fri May 13 03:08:31 2022 -0300

    libstdc++: ppc: conditionalize vsx-only simd intrinsics
    
    libstdc++'s bits/simd.h section for PowerPC, guarded by __ALTIVEC__,
    defines various intrinsic vector types that are only available with
    __VSX__: 64-bit long double, double, (un)signed long long, and 64-bit
    (un)signed long.
    
    experimental/simd/standard_abi_usable{,_2}.cc tests error out
    reporting the unmet requirements when the target cpu doesn't enable
    VSX.  Make the reported instrinsic types conditional on __VSX__ so
    that <experimental/simd> can be used on PowerPC variants that do not
    support VSX.
    
    
    for  libstdc++-v3/ChangeLog
    
            * include/experimental/bits/simd.h [__ALTIVEC__]: Require VSX
            for double, long long, and 64-bit long intrinsic types.
            [__ALTIVEC__] (__intrinsic_type): Mention 128-bit in
            preexisting long double diagnostic, adjust no-VSX double
            diagnostic to cover 64-bit long double as well.
    
    (cherry picked from commit 469c76f0d94d03e29467a9d1e77cd3613f46ac2f)

Diff:
---
 libstdc++-v3/include/experimental/bits/simd.h | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/libstdc++-v3/include/experimental/bits/simd.h b/libstdc++-v3/include/experimental/bits/simd.h
index 421c923e7b0..0e58ae01b17 100644
--- a/libstdc++-v3/include/experimental/bits/simd.h
+++ b/libstdc++-v3/include/experimental/bits/simd.h
@@ -2303,17 +2303,23 @@ template <typename _Tp>
   template <>                                                                  \
     struct __intrinsic_type_impl<_Tp> { using type = __vector _Tp; }
 _GLIBCXX_SIMD_PPC_INTRIN(float);
+#ifdef __VSX__
 _GLIBCXX_SIMD_PPC_INTRIN(double);
+#endif
 _GLIBCXX_SIMD_PPC_INTRIN(signed char);
 _GLIBCXX_SIMD_PPC_INTRIN(unsigned char);
 _GLIBCXX_SIMD_PPC_INTRIN(signed short);
 _GLIBCXX_SIMD_PPC_INTRIN(unsigned short);
 _GLIBCXX_SIMD_PPC_INTRIN(signed int);
 _GLIBCXX_SIMD_PPC_INTRIN(unsigned int);
+#if defined __VSX__ || __SIZEOF_LONG__ == 4
 _GLIBCXX_SIMD_PPC_INTRIN(signed long);
 _GLIBCXX_SIMD_PPC_INTRIN(unsigned long);
+#endif
+#ifdef __VSX__
 _GLIBCXX_SIMD_PPC_INTRIN(signed long long);
 _GLIBCXX_SIMD_PPC_INTRIN(unsigned long long);
+#endif
 #undef _GLIBCXX_SIMD_PPC_INTRIN
 
 template <typename _Tp, size_t _Bytes>
@@ -2323,10 +2329,11 @@ template <typename _Tp, size_t _Bytes>
     static constexpr bool _S_is_ldouble = is_same_v<_Tp, long double>;
     // allow _Tp == long double with -mlong-double-64
     static_assert(!(_S_is_ldouble && sizeof(long double) > sizeof(double)),
-		  "no __intrinsic_type support for long double on PPC");
+		  "no __intrinsic_type support for 128-bit floating point on PowerPC");
 #ifndef __VSX__
-    static_assert(!is_same_v<_Tp, double>,
-		  "no __intrinsic_type support for double on PPC w/o VSX");
+    static_assert(!(is_same_v<_Tp, double>
+		    || (_S_is_ldouble && sizeof(long double) == sizeof(double))),
+		  "no __intrinsic_type support for 64-bit floating point on PowerPC w/o VSX");
 #endif
     using type =
       typename __intrinsic_type_impl<