12 files changed, 545 insertions, 1 deletions
diff --git a/libcxx/include/__bit/bit_cast.h b/libcxx/include/__bit/bit_cast.h
index 831207671ec9..2ca4120c7630 100644
--- a/libcxx/include/__bit/bit_cast.h
+++ b/libcxx/include/__bit/bit_cast.h
@@ -11,7 +11,7 @@
 #define _LIBCPP___BIT_BIT_CAST_H
 
 #include <__config>
-#include <type_traits>
+#include <__type_traits/is_trivially_copyable.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
diff --git a/libcxx/include/__bit/bit_ceil.h b/libcxx/include/__bit/bit_ceil.h
new file mode 100644
index 000000000000..a558d6194270
--- /dev/null
+++ b/libcxx/include/__bit/bit_ceil.h
@@ -0,0 +1,46 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___BIT_BIT_CEIL_H
+#define _LIBCPP___BIT_BIT_CEIL_H
+
+#include <__assert>
+#include <__bit/countl.h>
+#include <__concepts/arithmetic.h>
+#include <__config>
+#include <limits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 20
+
+template <__libcpp_unsigned_integer _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr _Tp bit_ceil(_Tp __t) noexcept {
+  if (__t < 2)
+    return 1;
+  const unsigned __n = numeric_limits<_Tp>::digits - std::countl_zero((_Tp)(__t - 1u));
+  _LIBCPP_ASSERT(__n != numeric_limits<_Tp>::digits, "Bad input to bit_ceil");
+
+  if constexpr (sizeof(_Tp) >= sizeof(unsigned))
+    return _Tp{1} << __n;
+  else {
+    const unsigned __extra = numeric_limits<unsigned>::digits - numeric_limits<_Tp>::digits;
+    const unsigned __retVal = 1u << (__n + __extra);
+    return (_Tp)(__retVal >> __extra);
+  }
+}
+
+#endif // _LIBCPP_STD_VER >= 20
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___BIT_BIT_CEIL_H
diff --git a/libcxx/include/__bit/bit_floor.h b/libcxx/include/__bit/bit_floor.h
new file mode 100644
index 000000000000..b2e38092f2d7
--- /dev/null
+++ b/libcxx/include/__bit/bit_floor.h
@@ -0,0 +1,34 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___BIT_BIT_FLOOR_H
+#define _LIBCPP___BIT_BIT_FLOOR_H
+
+#include <__bit/bit_log2.h>
+#include <__concepts/arithmetic.h>
+#include <__config>
+#include <limits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 20
+
+template <__libcpp_unsigned_integer _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr _Tp bit_floor(_Tp __t) noexcept {
+  return __t == 0 ? 0 : _Tp{1} << std::__bit_log2(__t);
+}
+
+#endif // _LIBCPP_STD_VER >= 20
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___BIT_BIT_FLOOR_H
diff --git a/libcxx/include/__bit/bit_log2.h b/libcxx/include/__bit/bit_log2.h
new file mode 100644
index 000000000000..62936f678686
--- /dev/null
+++ b/libcxx/include/__bit/bit_log2.h
@@ -0,0 +1,34 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___BIT_BIT_LOG2_H
+#define _LIBCPP___BIT_BIT_LOG2_H
+
+#include <__bit/countl.h>
+#include <__concepts/arithmetic.h>
+#include <__config>
+#include <limits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 20
+
+template <__libcpp_unsigned_integer _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr _Tp __bit_log2(_Tp __t) noexcept {
+  return numeric_limits<_Tp>::digits - 1 - std::countl_zero(__t);
+}
+
+#endif // _LIBCPP_STD_VER >= 20
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___BIT_BIT_LOG2_H
diff --git a/libcxx/include/__bit/bit_width.h b/libcxx/include/__bit/bit_width.h
new file mode 100644
index 000000000000..4381f227f5e5
--- /dev/null
+++ b/libcxx/include/__bit/bit_width.h
@@ -0,0 +1,33 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___BIT_BIT_WIDTH_H
+#define _LIBCPP___BIT_BIT_WIDTH_H
+
+#include <__bit/bit_log2.h>
+#include <__concepts/arithmetic.h>
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#if _LIBCPP_STD_VER >= 20
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <__libcpp_unsigned_integer _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr int bit_width(_Tp __t) noexcept {
+  return __t == 0 ? 0 : std::__bit_log2(__t) + 1;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER >= 20
+
+#endif // _LIBCPP___BIT_BIT_WIDTH_H
diff --git a/libcxx/include/__bit/blsr.h b/libcxx/include/__bit/blsr.h
new file mode 100644
index 000000000000..de991e9adb3b
--- /dev/null
+++ b/libcxx/include/__bit/blsr.h
@@ -0,0 +1,34 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___BIT_BLSR_H
+#define _LIBCPP___BIT_BLSR_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR unsigned __libcpp_blsr(unsigned __x) _NOEXCEPT {
+  return __x ^ (__x & -__x);
+}
+
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR unsigned long __libcpp_blsr(unsigned long __x) _NOEXCEPT {
+  return __x ^ (__x & -__x);
+}
+
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR unsigned long long __libcpp_blsr(unsigned long long __x) _NOEXCEPT {
+  return __x ^ (__x & -__x);
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___BIT_BLSR_H
diff --git a/libcxx/include/__bit/countl.h b/libcxx/include/__bit/countl.h
new file mode 100644
index 000000000000..86eaee0c1b3b
--- /dev/null
+++ b/libcxx/include/__bit/countl.h
@@ -0,0 +1,104 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___BIT_COUNTL_H
+#define _LIBCPP___BIT_COUNTL_H
+
+#include <__bit/rotate.h>
+#include <__concepts/arithmetic.h>
+#include <__config>
+#include <__type_traits/is_unsigned_integer.h>
+#include <limits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+int __libcpp_clz(unsigned __x)           _NOEXCEPT { return __builtin_clz(__x); }
+
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+int __libcpp_clz(unsigned long __x)      _NOEXCEPT { return __builtin_clzl(__x); }
+
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+int __libcpp_clz(unsigned long long __x) _NOEXCEPT { return __builtin_clzll(__x); }
+
+#  ifndef _LIBCPP_HAS_NO_INT128
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+int __libcpp_clz(__uint128_t __x) _NOEXCEPT {
+  // The function is written in this form due to C++ constexpr limitations.
+  // The algorithm:
+  // - Test whether any bit in the high 64-bits is set
+  // - No bits set:
+  //   - The high 64-bits contain 64 leading zeros,
+  //   - Add the result of the low 64-bits.
+  // - Any bits set:
+  //   - The number of leading zeros of the input is the number of leading
+  //     zeros in the high 64-bits.
+  return ((__x >> 64) == 0)
+           ? (64 + __builtin_clzll(static_cast<unsigned long long>(__x)))
+           : __builtin_clzll(static_cast<unsigned long long>(__x >> 64));
+}
+#  endif // _LIBCPP_HAS_NO_INT128
+
+template<class _Tp>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14
+int __countl_zero(_Tp __t) _NOEXCEPT
+{
+    static_assert(__libcpp_is_unsigned_integer<_Tp>::value, "__countl_zero requires an unsigned integer type");
+    if (__t == 0)
+        return numeric_limits<_Tp>::digits;
+
+    if      (sizeof(_Tp) <= sizeof(unsigned int))
+        return std::__libcpp_clz(static_cast<unsigned int>(__t))
+              - (numeric_limits<unsigned int>::digits - numeric_limits<_Tp>::digits);
+    else if (sizeof(_Tp) <= sizeof(unsigned long))
+        return std::__libcpp_clz(static_cast<unsigned long>(__t))
+              - (numeric_limits<unsigned long>::digits - numeric_limits<_Tp>::digits);
+    else if (sizeof(_Tp) <= sizeof(unsigned long long))
+        return std::__libcpp_clz(static_cast<unsigned long long>(__t))
+              - (numeric_limits<unsigned long long>::digits - numeric_limits<_Tp>::digits);
+    else
+    {
+        int __ret = 0;
+        int __iter = 0;
+        const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits;
+        while (true) {
+            __t = std::__rotr(__t, __ulldigits);
+            if ((__iter = std::__countl_zero(static_cast<unsigned long long>(__t))) != __ulldigits)
+                break;
+            __ret += __iter;
+            }
+        return __ret + __iter;
+    }
+}
+
+#if _LIBCPP_STD_VER >= 20
+
+template <__libcpp_unsigned_integer _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr int countl_zero(_Tp __t) noexcept {
+  return std::__countl_zero(__t);
+}
+
+template <__libcpp_unsigned_integer _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr int countl_one(_Tp __t) noexcept {
+  return __t != numeric_limits<_Tp>::max() ? std::countl_zero(static_cast<_Tp>(~__t)) : numeric_limits<_Tp>::digits;
+}
+
+#endif // _LIBCPP_STD_VER >= 20
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___BIT_COUNTL_H
diff --git a/libcxx/include/__bit/countr.h b/libcxx/include/__bit/countr.h
new file mode 100644
index 000000000000..d3ca5b6c94f1
--- /dev/null
+++ b/libcxx/include/__bit/countr.h
@@ -0,0 +1,70 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___BIT_COUNTR_H
+#define _LIBCPP___BIT_COUNTR_H
+
+#include <__bit/rotate.h>
+#include <__concepts/arithmetic.h>
+#include <__config>
+#include <limits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+int __libcpp_ctz(unsigned __x)           _NOEXCEPT { return __builtin_ctz(__x); }
+
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+int __libcpp_ctz(unsigned long __x)      _NOEXCEPT { return __builtin_ctzl(__x); }
+
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+int __libcpp_ctz(unsigned long long __x) _NOEXCEPT { return __builtin_ctzll(__x); }
+
+#if _LIBCPP_STD_VER >= 20
+
+template <__libcpp_unsigned_integer _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr int countr_zero(_Tp __t) noexcept {
+  if (__t == 0)
+    return numeric_limits<_Tp>::digits;
+
+  if (sizeof(_Tp) <= sizeof(unsigned int))
+    return std::__libcpp_ctz(static_cast<unsigned int>(__t));
+  else if (sizeof(_Tp) <= sizeof(unsigned long))
+    return std::__libcpp_ctz(static_cast<unsigned long>(__t));
+  else if (sizeof(_Tp) <= sizeof(unsigned long long))
+    return std::__libcpp_ctz(static_cast<unsigned long long>(__t));
+  else {
+    int __ret = 0;
+    const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits;
+    while (static_cast<unsigned long long>(__t) == 0uLL) {
+      __ret += __ulldigits;
+      __t >>= __ulldigits;
+    }
+    return __ret + std::__libcpp_ctz(static_cast<unsigned long long>(__t));
+  }
+}
+
+template <__libcpp_unsigned_integer _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr int countr_one(_Tp __t) noexcept {
+  return __t != numeric_limits<_Tp>::max() ? std::countr_zero(static_cast<_Tp>(~__t)) : numeric_limits<_Tp>::digits;
+}
+
+#endif // _LIBCPP_STD_VER >= 20
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___BIT_COUNTR_H
diff --git a/libcxx/include/__bit/endian.h b/libcxx/include/__bit/endian.h
new file mode 100644
index 000000000000..52635f2d2495
--- /dev/null
+++ b/libcxx/include/__bit/endian.h
@@ -0,0 +1,38 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___BIT_ENDIAN_H
+#define _LIBCPP___BIT_ENDIAN_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#if _LIBCPP_STD_VER >= 20
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+enum class endian {
+  little = 0xDEAD,
+  big = 0xFACE,
+#  if defined(_LIBCPP_LITTLE_ENDIAN)
+  native = little
+#  elif defined(_LIBCPP_BIG_ENDIAN)
+  native = big
+#  else
+  native = 0xCAFE
+#  endif
+};
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER >= 20
+
+#endif // _LIBCPP___BIT_ENDIAN_H
diff --git a/libcxx/include/__bit/has_single_bit.h b/libcxx/include/__bit/has_single_bit.h
new file mode 100644
index 000000000000..b89f5995b32d
--- /dev/null
+++ b/libcxx/include/__bit/has_single_bit.h
@@ -0,0 +1,37 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___BIT_HAS_SINGLE_BIT_H
+#define _LIBCPP___BIT_HAS_SINGLE_BIT_H
+
+#include <__concepts/arithmetic.h>
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+#if _LIBCPP_STD_VER >= 20
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <__libcpp_unsigned_integer _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr bool has_single_bit(_Tp __t) noexcept {
+  return __t != 0 && (((__t & (__t - 1)) == 0));
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER >= 20
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___BIT_HAS_SINGLE_BIT_H
diff --git a/libcxx/include/__bit/popcount.h b/libcxx/include/__bit/popcount.h
new file mode 100644
index 000000000000..33b94cff7122
--- /dev/null
+++ b/libcxx/include/__bit/popcount.h
@@ -0,0 +1,61 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___BIT_POPCOUNT_H
+#define _LIBCPP___BIT_POPCOUNT_H
+
+#include <__bit/rotate.h>
+#include <__concepts/arithmetic.h>
+#include <__config>
+#include <limits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+int __libcpp_popcount(unsigned __x)           _NOEXCEPT { return __builtin_popcount(__x); }
+
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+int __libcpp_popcount(unsigned long __x)      _NOEXCEPT { return __builtin_popcountl(__x); }
+
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+int __libcpp_popcount(unsigned long long __x) _NOEXCEPT { return __builtin_popcountll(__x); }
+
+#if _LIBCPP_STD_VER >= 20
+
+template <__libcpp_unsigned_integer _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr int popcount(_Tp __t) noexcept {
+  if (sizeof(_Tp) <= sizeof(unsigned int))
+    return std::__libcpp_popcount(static_cast<unsigned int>(__t));
+  else if (sizeof(_Tp) <= sizeof(unsigned long))
+    return std::__libcpp_popcount(static_cast<unsigned long>(__t));
+  else if (sizeof(_Tp) <= sizeof(unsigned long long))
+    return std::__libcpp_popcount(static_cast<unsigned long long>(__t));
+  else {
+    int __ret = 0;
+    while (__t != 0) {
+      __ret += std::__libcpp_popcount(static_cast<unsigned long long>(__t));
+      __t >>= numeric_limits<unsigned long long>::digits;
+    }
+    return __ret;
+  }
+}
+
+#endif // _LIBCPP_STD_VER >= 20
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___BIT_POPCOUNT_H
diff --git a/libcxx/include/__bit/rotate.h b/libcxx/include/__bit/rotate.h
new file mode 100644
index 000000000000..5aa7518b3c57
--- /dev/null
+++ b/libcxx/include/__bit/rotate.h
@@ -0,0 +1,53 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___BIT_ROTATE_H
+#define _LIBCPP___BIT_ROTATE_H
+
+#include <__concepts/arithmetic.h>
+#include <__config>
+#include <__type_traits/is_unsigned_integer.h>
+#include <limits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template<class _Tp>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14
+_Tp __rotr(_Tp __t, unsigned int __cnt) _NOEXCEPT
+{
+    static_assert(__libcpp_is_unsigned_integer<_Tp>::value, "__rotr requires an unsigned integer type");
+    const unsigned int __dig = numeric_limits<_Tp>::digits;
+    if ((__cnt % __dig) == 0)
+        return __t;
+    return (__t >> (__cnt % __dig)) | (__t << (__dig - (__cnt % __dig)));
+}
+
+#if _LIBCPP_STD_VER >= 20
+
+template <__libcpp_unsigned_integer _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr _Tp rotl(_Tp __t, unsigned int __cnt) noexcept {
+  const unsigned int __dig = numeric_limits<_Tp>::digits;
+  if ((__cnt % __dig) == 0)
+    return __t;
+  return (__t << (__cnt % __dig)) | (__t >> (__dig - (__cnt % __dig)));
+}
+
+template <__libcpp_unsigned_integer _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr _Tp rotr(_Tp __t, unsigned int __cnt) noexcept {
+  return std::__rotr(__t, __cnt);
+}
+
+#endif // _LIBCPP_STD_VER >= 20
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___BIT_ROTATE_H