[gcc r11-10543] libstdc++: Simplify three helper functions into one

[Matthias Kretz <mkretz@gcc.gnu.org>]

https://gcc.gnu.org/g:a1f70114f9bae5a1dbcec4b556c16716601fccf1

commit r11-10543-ga1f70114f9bae5a1dbcec4b556c16716601fccf1
Author: Matthias Kretz <m.kretz@gsi.de>
Date:   Sat Jan 14 23:32:38 2023 +0100

    libstdc++: Simplify three helper functions into one
    
    Broadcast is a very common function. This should reduce compile-time
    effort.
    
    Signed-off-by: Matthias Kretz <m.kretz@gsi.de>
    
    libstdc++-v3/ChangeLog:
    
            PR libstdc++/108030
            * include/experimental/bits/simd.h (__vector_broadcast):
            Implement via __vector_broadcast_impl instead of
            __call_with_n_evaluations + 2 lambdas.
            (__vector_broadcast_impl): New.
    
    (cherry picked from commit 2e29e2fbeb8936e5c85cefaf547cba42e17e137b)

Diff:
---
 libstdc++-v3/include/experimental/bits/simd.h | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/libstdc++-v3/include/experimental/bits/simd.h b/libstdc++-v3/include/experimental/bits/simd.h
index cd811df7bfc..abbde6110a4 100644
--- a/libstdc++-v3/include/experimental/bits/simd.h
+++ b/libstdc++-v3/include/experimental/bits/simd.h
@@ -1665,14 +1665,15 @@ template <typename _Tp, typename... _Args>
 
 // }}}
 // __vector_broadcast{{{
+template <size_t _Np, typename _Tp, size_t... _I>
+  _GLIBCXX_SIMD_INTRINSIC constexpr __vector_type_t<_Tp, _Np>
+  __vector_broadcast_impl(_Tp __x, index_sequence<_I...>)
+  { return __vector_type_t<_Tp, _Np>{((void)_I, __x)...}; }
+
 template <size_t _Np, typename _Tp>
   _GLIBCXX_SIMD_INTRINSIC constexpr __vector_type_t<_Tp, _Np>
   __vector_broadcast(_Tp __x)
-  {
-    return __call_with_n_evaluations<_Np>(
-      [](auto... __xx) { return __vector_type_t<_Tp, _Np>{__xx...}; },
-      [&__x](int) { return __x; });
-  }
+  { return __vector_broadcast_impl<_Np, _Tp>(__x, make_index_sequence<_Np>()); }
 
 // }}}
 // __generate_vector{{{