[libcxx-commits] [libcxx] [libc++] Use __builtin_bswapg to implement std::byteswap if it's available (PR #168557)

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``````````bash
git-clang-format --diff origin/main HEAD --extensions h -- libcxx/include/__bit/byteswap.h --diff_from_common_commit
``````````

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``````````diff
diff --git a/libcxx/include/__bit/byteswap.h b/libcxx/include/__bit/byteswap.h
index 7dd4fc38c..6103be5a7 100644
--- a/libcxx/include/__bit/byteswap.h
+++ b/libcxx/include/__bit/byteswap.h
@@ -24,9 +24,9 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 
 template <integral _Tp>
 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp byteswap(_Tp __val) noexcept {
-#if __has_builtin(__builtin_bswapg)
+#  if __has_builtin(__builtin_bswapg)
   return __builtin_bswapg(__val);
-#else
+#  else
   if constexpr (sizeof(_Tp) == 1) {
     return __val;
   } else if constexpr (sizeof(_Tp) == 2) {
@@ -35,19 +35,19 @@ template <integral _Tp>
     return __builtin_bswap32(__val);
   } else if constexpr (sizeof(_Tp) == 8) {
     return __builtin_bswap64(__val);
-#  if _LIBCPP_HAS_INT128
+#    if _LIBCPP_HAS_INT128
   } else if constexpr (sizeof(_Tp) == 16) {
-#    if __has_builtin(__builtin_bswap128)
+#      if __has_builtin(__builtin_bswap128)
     return __builtin_bswap128(__val);
-#    else
+#      else
     return static_cast<_Tp>(byteswap(static_cast<uint64_t>(__val))) << 64 |
            static_cast<_Tp>(byteswap(static_cast<uint64_t>(__val >> 64)));
-#    endif // __has_builtin(__builtin_bswap128)
-#  endif   // _LIBCPP_HAS_INT128
+#      endif // __has_builtin(__builtin_bswap128)
+#    endif   // _LIBCPP_HAS_INT128
   } else {
     static_assert(sizeof(_Tp) == 0, "byteswap is unimplemented for integral types of this size");
   }
-#endif
+#  endif
 }
 
 #endif // _LIBCPP_STD_VER >= 23

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https://github.com/llvm/llvm-project/pull/168557