[PATCH 4/8] libstdc++: Add missing constexpr on simd shift implementation

[Matthias Kretz via Gcc-patches]

Resolves -Wtautological-compare warnings about `if
(__builtin_is_constant_evaluated())` in the implementations of these
functions.

Signed-off-by: Matthias Kretz <m.kr...@gsi.de>

libstdc++-v3/ChangeLog:

        * include/experimental/bits/simd_x86.h (_S_bit_shift_left)
        (_S_bit_shift_right): Declare constexpr. The implementation was
        already expecting constexpr evaluation.
---
 libstdc++-v3/include/experimental/bits/simd_x86.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)


--
──────────────────────────────────────────────────────────────────────────
 Dr. Matthias Kretz                           https://mattkretz.github.io
 GSI Helmholtz Centre for Heavy Ion Research               https://gsi.de
 stdₓ::simd
──────────────────────────────────────────────────────────────────────────
diff --git a/libstdc++-v3/include/experimental/bits/simd_x86.h b/libstdc++-v3/include/experimental/bits/simd_x86.h
index 897a67829d1..8872ca301b9 100644
--- a/libstdc++-v3/include/experimental/bits/simd_x86.h
+++ b/libstdc++-v3/include/experimental/bits/simd_x86.h
@@ -1526,7 +1526,7 @@ _S_modulus(_SimdWrapper<_Tp, _Np> __x, _SimdWrapper<_Tp, _Np> __y)
     // values.
   #ifndef _GLIBCXX_SIMD_NO_SHIFT_OPT
     template <typename _Tp, typename _TVT = _VectorTraits<_Tp>>
-      inline _GLIBCXX_CONST static typename _TVT::type
+      constexpr inline _GLIBCXX_CONST static typename _TVT::type
       _S_bit_shift_left(_Tp __xx, int __y)
       {
 	using _V = typename _TVT::type;
@@ -1631,7 +1631,7 @@ unsigned(
       }
 
     template <typename _Tp, typename _TVT = _VectorTraits<_Tp>>
-      inline _GLIBCXX_CONST static typename _TVT::type
+      constexpr inline _GLIBCXX_CONST static typename _TVT::type
       _S_bit_shift_left(_Tp __xx, typename _TVT::type __y)
       {
 	using _V = typename _TVT::type;
@@ -1800,7 +1800,7 @@ _mm512_cvtepi16_epi8(
     // _S_bit_shift_right {{{
 #ifndef _GLIBCXX_SIMD_NO_SHIFT_OPT
     template <typename _Tp, typename _TVT = _VectorTraits<_Tp>>
-      inline _GLIBCXX_CONST static typename _TVT::type
+      constexpr inline _GLIBCXX_CONST static typename _TVT::type
       _S_bit_shift_right(_Tp __xx, int __y)
       {
 	using _V = typename _TVT::type;
@@ -1850,7 +1850,7 @@ _S_bit_shift_right(_Tp __xx, int __y)
       }
 
     template <typename _Tp, typename _TVT = _VectorTraits<_Tp>>
-      inline _GLIBCXX_CONST static typename _TVT::type
+      constexpr inline _GLIBCXX_CONST static typename _TVT::type
       _S_bit_shift_right(_Tp __xx, typename _TVT::type __y)
       {
 	using _V = typename _TVT::type;