Library import 16 (#2433)

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1 files changed, 219 insertions, 0 deletions

diff --git a/contrib/libs/cxxsupp/libcxx/include/__string/constexpr_c_functions.h b/contrib/libs/cxxsupp/libcxx/include/__string/constexpr_c_functions.h
new file mode 100644
index 0000000000..198f0f5e68
--- /dev/null
+++ b/contrib/libs/cxxsupp/libcxx/include/__string/constexpr_c_functions.h
@@ -0,0 +1,219 @@
+//===----------------------------------------------------------------------===//
+//
+// 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___STRING_CONSTEXPR_C_FUNCTIONS_H
+#define _LIBCPP___STRING_CONSTEXPR_C_FUNCTIONS_H
+
+#include <__config>
+#include <__memory/addressof.h>
+#include <__memory/construct_at.h>
+#include <__type_traits/datasizeof.h>
+#include <__type_traits/is_always_bitcastable.h>
+#include <__type_traits/is_assignable.h>
+#include <__type_traits/is_constant_evaluated.h>
+#include <__type_traits/is_constructible.h>
+#include <__type_traits/is_equality_comparable.h>
+#include <__type_traits/is_same.h>
+#include <__type_traits/is_trivially_copyable.h>
+#include <__type_traits/is_trivially_lexicographically_comparable.h>
+#include <__type_traits/remove_cv.h>
+#include <__utility/is_pointer_in_range.h>
+#include <cstddef>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// Type used to encode that a function takes an integer that represents a number
+// of elements as opposed to a number of bytes.
+enum class __element_count : size_t {};
+
+inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 size_t __constexpr_strlen(const char* __str) {
+  // GCC currently doesn't support __builtin_strlen for heap-allocated memory during constant evaluation.
+  // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70816
+#ifdef _LIBCPP_COMPILER_GCC
+  if (__libcpp_is_constant_evaluated()) {
+    size_t __i = 0;
+    for (; __str[__i] != '\0'; ++__i)
+      ;
+    return __i;
+  }
+#endif
+  return __builtin_strlen(__str);
+}
+
+// Because of __libcpp_is_trivially_lexicographically_comparable we know that comparing the object representations is
+// equivalent to a std::memcmp. Since we have multiple objects contiguously in memory, we can call memcmp once instead
+// of invoking it on every object individually.
+template <class _Tp, class _Up>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 int
+__constexpr_memcmp(const _Tp* __lhs, const _Up* __rhs, __element_count __n) {
+  static_assert(__libcpp_is_trivially_lexicographically_comparable<_Tp, _Up>::value,
+                "_Tp and _Up have to be trivially lexicographically comparable");
+
+  auto __count = static_cast<size_t>(__n);
+
+  if (__libcpp_is_constant_evaluated()) {
+#ifdef _LIBCPP_COMPILER_CLANG_BASED
+    if (sizeof(_Tp) == 1 && !is_same<_Tp, bool>::value)
+      return __builtin_memcmp(__lhs, __rhs, __count * sizeof(_Tp));
+#endif
+
+    while (__count != 0) {
+      if (*__lhs < *__rhs)
+        return -1;
+      if (*__rhs < *__lhs)
+        return 1;
+
+      --__count;
+      ++__lhs;
+      ++__rhs;
+    }
+    return 0;
+  } else {
+    return __builtin_memcmp(__lhs, __rhs, __count * sizeof(_Tp));
+  }
+}
+
+// Because of __libcpp_is_trivially_equality_comparable we know that comparing the object representations is equivalent
+// to a std::memcmp(...) == 0. Since we have multiple objects contiguously in memory, we can call memcmp once instead
+// of invoking it on every object individually.
+template <class _Tp, class _Up>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 bool
+__constexpr_memcmp_equal(const _Tp* __lhs, const _Up* __rhs, __element_count __n) {
+  static_assert(__libcpp_is_trivially_equality_comparable<_Tp, _Up>::value,
+                "_Tp and _Up have to be trivially equality comparable");
+
+  auto __count = static_cast<size_t>(__n);
+
+  if (__libcpp_is_constant_evaluated()) {
+#ifdef _LIBCPP_COMPILER_CLANG_BASED
+    if (sizeof(_Tp) == 1 && is_integral<_Tp>::value && !is_same<_Tp, bool>::value)
+      return __builtin_memcmp(__lhs, __rhs, __count * sizeof(_Tp)) == 0;
+#endif
+    while (__count != 0) {
+      if (*__lhs != *__rhs)
+        return false;
+
+      --__count;
+      ++__lhs;
+      ++__rhs;
+    }
+    return true;
+  } else {
+    return __builtin_memcmp(__lhs, __rhs, __count * sizeof(_Tp)) == 0;
+  }
+}
+
+template <class _Tp, class _Up>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp* __constexpr_memchr(_Tp* __str, _Up __value, size_t __count) {
+  static_assert(sizeof(_Tp) == 1 && __libcpp_is_trivially_equality_comparable<_Tp, _Up>::value,
+                "Calling memchr on non-trivially equality comparable types is unsafe.");
+
+  if (__libcpp_is_constant_evaluated()) {
+// use __builtin_char_memchr to optimize constexpr evaluation if we can
+#if _LIBCPP_STD_VER >= 17 && __has_builtin(__builtin_char_memchr)
+    if constexpr (is_same_v<remove_cv_t<_Tp>, char> && is_same_v<remove_cv_t<_Up>, char>)
+      return __builtin_char_memchr(__str, __value, __count);
+#endif
+
+    for (; __count; --__count) {
+      if (*__str == __value)
+        return __str;
+      ++__str;
+    }
+    return nullptr;
+  } else {
+    char __value_buffer = 0;
+    __builtin_memcpy(&__value_buffer, &__value, sizeof(char));
+    return static_cast<_Tp*>(__builtin_memchr(__str, __value_buffer, __count));
+  }
+}
+
+// This function performs an assignment to an existing, already alive TriviallyCopyable object
+// from another TriviallyCopyable object.
+//
+// It basically works around the fact that TriviallyCopyable objects are not required to be
+// syntactically copy/move constructible or copy/move assignable. Technically, only one of the
+// four operations is required to be syntactically valid -- but at least one definitely has to
+// be valid.
+//
+// This is necessary in order to implement __constexpr_memmove below in a way that mirrors as
+// closely as possible what the compiler's __builtin_memmove is able to do.
+template <class _Tp, class _Up, __enable_if_t<is_assignable<_Tp&, _Up const&>::value, int> = 0>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp& __assign_trivially_copyable(_Tp& __dest, _Up const& __src) {
+  __dest = __src;
+  return __dest;
+}
+
+// clang-format off
+template <class _Tp, class _Up, __enable_if_t<!is_assignable<_Tp&, _Up const&>::value &&
+                                               is_assignable<_Tp&, _Up&&>::value, int> = 0>
+// clang-format on
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp& __assign_trivially_copyable(_Tp& __dest, _Up& __src) {
+  __dest =
+      static_cast<_Up&&>(__src); // this is safe, we're not actually moving anything since the assignment is trivial
+  return __dest;
+}
+
+// clang-format off
+template <class _Tp, class _Up, __enable_if_t<!is_assignable<_Tp&, _Up const&>::value &&
+                                              !is_assignable<_Tp&, _Up&&>::value &&
+                                               is_constructible<_Tp, _Up const&>::value, int> = 0>
+// clang-format on
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp& __assign_trivially_copyable(_Tp& __dest, _Up const& __src) {
+  // _Tp is trivially destructible, so we don't need to call its destructor to end the lifetime of the object
+  // that was there previously
+  std::__construct_at(std::addressof(__dest), __src);
+  return __dest;
+}
+
+// clang-format off
+template <class _Tp, class _Up, __enable_if_t<!is_assignable<_Tp&, _Up const&>::value &&
+                                              !is_assignable<_Tp&, _Up&&>::value &&
+                                              !is_constructible<_Tp, _Up const&>::value &&
+                                               is_constructible<_Tp, _Up&&>::value, int> = 0>
+// clang-format on
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp& __assign_trivially_copyable(_Tp& __dest, _Up& __src) {
+  // _Tp is trivially destructible, so we don't need to call its destructor to end the lifetime of the object
+  // that was there previously
+  std::__construct_at(
+      std::addressof(__dest),
+      static_cast<_Up&&>(__src)); // this is safe, we're not actually moving anything since the constructor is trivial
+  return __dest;
+}
+
+template <class _Tp, class _Up, __enable_if_t<__is_always_bitcastable<_Up, _Tp>::value, int> = 0>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp*
+__constexpr_memmove(_Tp* __dest, _Up* __src, __element_count __n) {
+  size_t __count = static_cast<size_t>(__n);
+  if (__libcpp_is_constant_evaluated()) {
+#ifdef _LIBCPP_COMPILER_CLANG_BASED
+    if (is_same<__remove_cv_t<_Tp>, __remove_cv_t<_Up> >::value) {
+      ::__builtin_memmove(__dest, __src, __count * sizeof(_Tp));
+      return __dest;
+    }
+#endif
+    if (std::__is_pointer_in_range(__src, __src + __count, __dest)) {
+      for (; __count > 0; --__count)
+        std::__assign_trivially_copyable(__dest[__count - 1], __src[__count - 1]);
+    } else {
+      for (size_t __i = 0; __i != __count; ++__i)
+        std::__assign_trivially_copyable(__dest[__i], __src[__i]);
+    }
+  } else if (__count > 0) {
+    ::__builtin_memmove(__dest, __src, (__count - 1) * sizeof(_Tp) + __libcpp_datasizeof<_Tp>::value);
+  }
+  return __dest;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___STRING_CONSTEXPR_C_FUNCTIONS_H