// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// 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_TYPEINFO
#define _LIBCPP_TYPEINFO
/*
typeinfo synopsis
namespace std {
class type_info
{
public:
virtual ~type_info();
bool operator==(const type_info& rhs) const noexcept; // constexpr since C++23
bool operator!=(const type_info& rhs) const noexcept; // removed in C++20
bool before(const type_info& rhs) const noexcept;
size_t hash_code() const noexcept;
const char* name() const noexcept;
type_info(const type_info& rhs) = delete;
type_info& operator=(const type_info& rhs) = delete;
};
class bad_cast
: public exception
{
public:
bad_cast() noexcept;
bad_cast(const bad_cast&) noexcept;
bad_cast& operator=(const bad_cast&) noexcept;
virtual const char* what() const noexcept;
};
class bad_typeid
: public exception
{
public:
bad_typeid() noexcept;
bad_typeid(const bad_typeid&) noexcept;
bad_typeid& operator=(const bad_typeid&) noexcept;
virtual const char* what() const noexcept;
};
} // std
*/
#include <__config>
#include <__exception/exception.h>
#include <__type_traits/is_constant_evaluated.h>
#include <__verbose_abort>
#include <cstddef>
#include <cstdint>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
#if defined(_LIBCPP_ABI_VCRUNTIME)
# include <vcruntime_typeinfo.h>
#else
namespace std // purposefully not using versioning namespace
{
# if defined(_LIBCPP_ABI_MICROSOFT)
class _LIBCPP_EXPORTED_FROM_ABI type_info {
type_info& operator=(const type_info&);
type_info(const type_info&);
mutable struct {
const char* __undecorated_name;
const char __decorated_name[1];
} __data;
int __compare(const type_info& __rhs) const _NOEXCEPT;
public:
virtual ~type_info();
const char* name() const _NOEXCEPT;
_LIBCPP_HIDE_FROM_ABI bool before(const type_info& __arg) const _NOEXCEPT { return __compare(__arg) < 0; }
size_t hash_code() const _NOEXCEPT;
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool operator==(const type_info& __arg) const _NOEXCEPT {
// When evaluated in a constant expression, both type infos simply can't come
// from different translation units, so it is sufficient to compare their addresses.
if (__libcpp_is_constant_evaluated()) {
return this == &__arg;
}
return __compare(__arg) == 0;
}
# if _LIBCPP_STD_VER <= 17
_LIBCPP_HIDE_FROM_ABI bool operator!=(const type_info& __arg) const _NOEXCEPT { return !operator==(__arg); }
# endif
};
# else // !defined(_LIBCPP_ABI_MICROSOFT)
// ========================================================================== //
// Implementations
// ========================================================================== //
// ------------------------------------------------------------------------- //
// Unique
// (_LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION = 1)
// ------------------------------------------------------------------------- //
// This implementation of type_info assumes a unique copy of the RTTI for a
// given type inside a program. This is a valid assumption when abiding to the
// Itanium ABI (http://itanium-cxx-abi.github.io/cxx-abi/abi.html#vtable-components).
// Under this assumption, we can always compare the addresses of the type names
// to implement equality-comparison of type_infos instead of having to perform
// a deep string comparison.
// -------------------------------------------------------------------------- //
// NonUnique
// (_LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION = 2)
// -------------------------------------------------------------------------- //
// This implementation of type_info does not assume there is always a unique
// copy of the RTTI for a given type inside a program. For various reasons
// the linker may have failed to merge every copy of a types RTTI
// (For example: -Bsymbolic or llvm.org/PR37398). Under this assumption, two
// type_infos are equal if their addresses are equal or if a deep string
// comparison is equal.
// -------------------------------------------------------------------------- //
// NonUniqueARMRTTIBit
// (_LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION = 3)
// -------------------------------------------------------------------------- //
// This implementation is specific to ARM64 on Apple platforms.
//
// This implementation of type_info does not assume always a unique copy of
// the RTTI for a given type inside a program. When constructing the type_info,
// the compiler packs the pointer to the type name into a uintptr_t and reserves
// the high bit of that pointer, which is assumed to be free for use under that
// ABI. If that high bit is set, that specific copy of the RTTI can't be assumed
// to be unique within the program. If the high bit is unset, then the RTTI can
// be assumed to be unique within the program.
//
// When comparing type_infos, if both RTTIs can be assumed to be unique, it
// suffices to compare their addresses. If both the RTTIs can't be assumed to
// be unique, we must perform a deep string comparison of the type names.
// However, if one of the RTTIs is guaranteed unique and the other one isn't,
// then both RTTIs are necessarily not to be considered equal.
//
// The intent of this design is to remove the need for weak symbols. Specifically,
// if a type would normally have a default-visibility RTTI emitted as a weak
// symbol, it is given hidden visibility instead and the non-unique bit is set.
// Otherwise, types declared with hidden visibility are always considered to have
// a unique RTTI: the RTTI is emitted with linkonce_odr linkage and is assumed
// to be deduplicated by the linker within the linked image. Across linked image
// boundaries, such types are thus considered different types.
// This value can be overriden in the __config_site. When it's not overriden,
// we pick a default implementation based on the platform here.
# ifndef _LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION
// Windows and AIX binaries can't merge typeinfos, so use the NonUnique implementation.
# if defined(_LIBCPP_OBJECT_FORMAT_COFF) || defined(_LIBCPP_OBJECT_FORMAT_XCOFF)
# define _LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION 2
// On arm64 on Apple platforms, use the special NonUniqueARMRTTIBit implementation.
# elif defined(__APPLE__) && defined(__LP64__) && !defined(__x86_64__)
# define _LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION 3
// On all other platforms, assume the Itanium C++ ABI and use the Unique implementation.
# else
# define _LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION 1
# endif
# endif
struct __type_info_implementations {
struct __string_impl_base {
typedef const char* __type_name_t;
_LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE _LIBCPP_CONSTEXPR static const char*
__type_name_to_string(__type_name_t __v) _NOEXCEPT {
return __v;
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE _LIBCPP_CONSTEXPR static __type_name_t
__string_to_type_name(const char* __v) _NOEXCEPT {
return __v;
}
};
struct __unique_impl : __string_impl_base {
_LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE static size_t __hash(__type_name_t __v) _NOEXCEPT {
return reinterpret_cast<size_t>(__v);
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE static bool __eq(__type_name_t __lhs, __type_name_t __rhs) _NOEXCEPT {
return __lhs == __rhs;
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE static bool __lt(__type_name_t __lhs, __type_name_t __rhs) _NOEXCEPT {
return __lhs < __rhs;
}
};
struct __non_unique_impl : __string_impl_base {
_LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE static size_t __hash(__type_name_t __ptr) _NOEXCEPT {
size_t __hash = 5381;
while (unsigned char __c = static_cast<unsigned char>(*__ptr++))
__hash = (__hash * 33) ^ __c;
return __hash;
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE static bool __eq(__type_name_t __lhs, __type_name_t __rhs) _NOEXCEPT {
return __lhs == __rhs || __builtin_strcmp(__lhs, __rhs) == 0;
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE static bool __lt(__type_name_t __lhs, __type_name_t __rhs) _NOEXCEPT {
return __builtin_strcmp(__lhs, __rhs) < 0;
}
};
struct __non_unique_arm_rtti_bit_impl {
typedef uintptr_t __type_name_t;
_LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE static const char* __type_name_to_string(__type_name_t __v) _NOEXCEPT {
return reinterpret_cast<const char*>(__v & ~__non_unique_rtti_bit::value);
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE static __type_name_t __string_to_type_name(const char* __v) _NOEXCEPT {
return reinterpret_cast<__type_name_t>(__v);
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE static size_t __hash(__type_name_t __v) _NOEXCEPT {
if (__is_type_name_unique(__v))
return __v;
return __non_unique_impl::__hash(__type_name_to_string(__v));
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE static bool __eq(__type_name_t __lhs, __type_name_t __rhs) _NOEXCEPT {
if (__lhs == __rhs)
return true;
if (__is_type_name_unique(__lhs) || __is_type_name_unique(__rhs))
// Either both are unique and have a different address, or one of them
// is unique and the other one isn't. In both cases they are unequal.
return false;
return __builtin_strcmp(__type_name_to_string(__lhs), __type_name_to_string(__rhs)) == 0;
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE static bool __lt(__type_name_t __lhs, __type_name_t __rhs) _NOEXCEPT {
if (__is_type_name_unique(__lhs) || __is_type_name_unique(__rhs))
return __lhs < __rhs;
return __builtin_strcmp(__type_name_to_string(__lhs), __type_name_to_string(__rhs)) < 0;
}
private:
// The unique bit is the top bit. It is expected that __type_name_t is 64 bits when
// this implementation is actually used.
typedef integral_constant<__type_name_t, (1ULL << ((__CHAR_BIT__ * sizeof(__type_name_t)) - 1))>
__non_unique_rtti_bit;
_LIBCPP_HIDE_FROM_ABI static bool __is_type_name_unique(__type_name_t __lhs) _NOEXCEPT {
return !(__lhs & __non_unique_rtti_bit::value);
}
};
typedef
# if _LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION == 1
__unique_impl
# elif _LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION == 2
__non_unique_impl
# elif _LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION == 3
__non_unique_arm_rtti_bit_impl
# else
# error invalid configuration for _LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION
# endif
__impl;
};
# if __has_cpp_attribute(_Clang::__ptrauth_vtable_pointer__)
# if __has_feature(ptrauth_type_info_vtable_pointer_discrimination)
# define _LIBCPP_TYPE_INFO_VTABLE_POINTER_AUTH \
[[_Clang::__ptrauth_vtable_pointer__(process_independent, address_discrimination, type_discrimination)]]
# else
# define _LIBCPP_TYPE_INFO_VTABLE_POINTER_AUTH \
[[_Clang::__ptrauth_vtable_pointer__( \
process_independent, no_address_discrimination, no_extra_discrimination)]]
# endif
# else
# define _LIBCPP_TYPE_INFO_VTABLE_POINTER_AUTH
# endif
class _LIBCPP_EXPORTED_FROM_ABI _LIBCPP_TYPE_INFO_VTABLE_POINTER_AUTH type_info {
type_info& operator=(const type_info&);
type_info(const type_info&);
protected:
typedef __type_info_implementations::__impl __impl;
__impl::__type_name_t __type_name;
_LIBCPP_HIDE_FROM_ABI explicit type_info(const char* __n) : __type_name(__impl::__string_to_type_name(__n)) {}
public:
virtual ~type_info();
_LIBCPP_HIDE_FROM_ABI const char* name() const _NOEXCEPT { return __impl::__type_name_to_string(__type_name); }
_LIBCPP_HIDE_FROM_ABI bool before(const type_info& __arg) const _NOEXCEPT {
return __impl::__lt(__type_name, __arg.__type_name);
}
_LIBCPP_HIDE_FROM_ABI size_t hash_code() const _NOEXCEPT { return __impl::__hash(__type_name); }
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool operator==(const type_info& __arg) const _NOEXCEPT {
// When evaluated in a constant expression, both type infos simply can't come
// from different translation units, so it is sufficient to compare their addresses.
if (__libcpp_is_constant_evaluated()) {
return this == &__arg;
}
return __impl::__eq(__type_name, __arg.__type_name);
}
# if _LIBCPP_STD_VER <= 17
_LIBCPP_HIDE_FROM_ABI bool operator!=(const type_info& __arg) const _NOEXCEPT { return !operator==(__arg); }
# endif
};
# endif // defined(_LIBCPP_ABI_MICROSOFT)
class _LIBCPP_EXPORTED_FROM_ABI bad_cast : public exception {
public:
bad_cast() _NOEXCEPT;
_LIBCPP_HIDE_FROM_ABI bad_cast(const bad_cast&) _NOEXCEPT = default;
_LIBCPP_HIDE_FROM_ABI bad_cast& operator=(const bad_cast&) _NOEXCEPT = default;
~bad_cast() _NOEXCEPT override;
const char* what() const _NOEXCEPT override;
};
class _LIBCPP_EXPORTED_FROM_ABI bad_typeid : public exception {
public:
bad_typeid() _NOEXCEPT;
_LIBCPP_HIDE_FROM_ABI bad_typeid(const bad_typeid&) _NOEXCEPT = default;
_LIBCPP_HIDE_FROM_ABI bad_typeid& operator=(const bad_typeid&) _NOEXCEPT = default;
~bad_typeid() _NOEXCEPT override;
const char* what() const _NOEXCEPT override;
};
} // namespace std
#endif // defined(_LIBCPP_ABI_VCRUNTIME)
#if defined(_LIBCPP_ABI_VCRUNTIME) && _HAS_EXCEPTIONS == 0
namespace std {
class bad_cast : public exception {
public:
bad_cast() _NOEXCEPT : exception("bad cast") {}
private:
bad_cast(const char* const __message) _NOEXCEPT : exception(__message) {}
};
class bad_typeid : public exception {
public:
bad_typeid() _NOEXCEPT : exception("bad typeid") {}
private:
bad_typeid(const char* const __message) _NOEXCEPT : exception(__message) {}
};
} // namespace std
#endif // defined(_LIBCPP_ABI_VCRUNTIME) && _HAS_EXCEPTIONS == 0
_LIBCPP_BEGIN_NAMESPACE_STD
_LIBCPP_NORETURN inline _LIBCPP_HIDE_FROM_ABI void __throw_bad_cast() {
#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
throw bad_cast();
#else
_LIBCPP_VERBOSE_ABORT("bad_cast was thrown in -fno-exceptions mode");
#endif
}
_LIBCPP_END_NAMESPACE_STD
#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
# include <cstdlib>
# include <type_traits>
#endif
#endif // _LIBCPP_TYPEINFO
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