1// -*- C++ -*-
2//===-------------------------- typeinfo ----------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef __LIBCPP_TYPEINFO
11#define __LIBCPP_TYPEINFO
12
13/*
14
15 typeinfo synopsis
16
17namespace std {
18
19class type_info
20{
21public:
22 virtual ~type_info();
23
24 bool operator==(const type_info& rhs) const noexcept;
25 bool operator!=(const type_info& rhs) const noexcept;
26
27 bool before(const type_info& rhs) const noexcept;
28 size_t hash_code() const noexcept;
29 const char* name() const noexcept;
30
31 type_info(const type_info& rhs) = delete;
32 type_info& operator=(const type_info& rhs) = delete;
33};
34
35class bad_cast
36 : public exception
37{
38public:
39 bad_cast() noexcept;
40 bad_cast(const bad_cast&) noexcept;
41 bad_cast& operator=(const bad_cast&) noexcept;
42 virtual const char* what() const noexcept;
43};
44
45class bad_typeid
46 : public exception
47{
48public:
49 bad_typeid() noexcept;
50 bad_typeid(const bad_typeid&) noexcept;
51 bad_typeid& operator=(const bad_typeid&) noexcept;
52 virtual const char* what() const noexcept;
53};
54
55} // std
56
57*/
58
59#include <__config>
60#include <exception>
61#include <cstddef>
62#include <cstdint>
63#ifdef _LIBCPP_NO_EXCEPTIONS
64#include <cstdlib>
65#endif
66
67#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
68#pragma GCC system_header
69#endif
70
71#if defined(_LIBCPP_ABI_VCRUNTIME)
72#include <vcruntime_typeinfo.h>
73#else
74
75namespace std // purposefully not using versioning namespace
76{
77
78
79#if defined(_LIBCPP_ABI_MICROSOFT)
80
81class _LIBCPP_EXCEPTION_ABI type_info
82{
83 type_info& operator=(const type_info&);
84 type_info(const type_info&);
85
86 mutable struct {
87 const char *__undecorated_name;
88 const char __decorated_name[1];
89 } __data;
90
91 int __compare(const type_info &__rhs) const _NOEXCEPT;
92
93public:
94 _LIBCPP_AVAILABILITY_TYPEINFO_VTABLE
95 virtual ~type_info();
96
97 const char *name() const _NOEXCEPT;
98
99 _LIBCPP_INLINE_VISIBILITY
100 bool before(const type_info& __arg) const _NOEXCEPT {
101 return __compare(__arg) < 0;
102 }
103
104 size_t hash_code() const _NOEXCEPT;
105
106 _LIBCPP_INLINE_VISIBILITY
107 bool operator==(const type_info& __arg) const _NOEXCEPT {
108 return __compare(__arg) == 0;
109 }
110
111 _LIBCPP_INLINE_VISIBILITY
112 bool operator!=(const type_info& __arg) const _NOEXCEPT
113 { return !operator==(__arg); }
114};
115
116#else // !defined(_LIBCPP_ABI_MICROSOFT)
117
118// ========================================================================== //
119// Implementations
120// ========================================================================== //
121// ------------------------------------------------------------------------- //
122// Unique
123// ------------------------------------------------------------------------- //
124// This implementation of type_info assumes a unique copy of the RTTI for a
125// given type inside a program. This is a valid assumption when abiding to
126// Itanium ABI (http://itanium-cxx-abi.github.io/cxx-abi/abi.html#vtable-components).
127// Under this assumption, we can always compare the addresses of the type names
128// to implement equality-comparison of type_infos instead of having to perform
129// a deep string comparison.
130// -------------------------------------------------------------------------- //
131// NonUnique
132// -------------------------------------------------------------------------- //
133// This implementation of type_info does not assume there is always a unique
134// copy of the RTTI for a given type inside a program. For various reasons
135// the linker may have failed to merge every copy of a types RTTI
136// (For example: -Bsymbolic or llvm.org/PR37398). Under this assumption, two
137// type_infos are equal if their addresses are equal or if a deep string
138// comparison is equal.
139// -------------------------------------------------------------------------- //
140// NonUniqueARMRTTIBit
141// -------------------------------------------------------------------------- //
142// This implementation of type_info does not assume always a unique copy of
143// the RTTI for a given type inside a program. It packs the pointer to the
144// type name into a uintptr_t and reserves the high bit of that pointer (which
145// is assumed to be free for use under the ABI in use) to represent whether
146// that specific copy of the RTTI can be assumed unique inside the program.
147// To implement equality-comparison of type_infos, we check whether BOTH
148// type_infos are guaranteed unique, and if so, we simply compare the addresses
149// of their type names instead of doing a deep string comparison, which is
150// faster. If at least one of the type_infos can't guarantee uniqueness, we
151// have no choice but to fall back to a deep string comparison.
152//
153// This implementation is specific to ARM64 on Apple platforms.
154//
155// Note that the compiler is the one setting (or unsetting) the high bit of
156// the pointer when it constructs the type_info, depending on whether it can
157// guarantee uniqueness for that specific type_info.
158
159struct __type_info_implementations {
160 struct __string_impl_base {
161 typedef const char* __type_name_t;
162 _LIBCPP_INLINE_VISIBILITY _LIBCPP_ALWAYS_INLINE
163 _LIBCPP_CONSTEXPR static const char* __type_name_to_string(__type_name_t __v) _NOEXCEPT {
164 return __v;
165 }
166 _LIBCPP_INLINE_VISIBILITY _LIBCPP_ALWAYS_INLINE
167 _LIBCPP_CONSTEXPR static __type_name_t __string_to_type_name(const char* __v) _NOEXCEPT {
168 return __v;
169 }
170 };
171
172 struct __unique_impl : __string_impl_base {
173 _LIBCPP_INLINE_VISIBILITY _LIBCPP_ALWAYS_INLINE
174 static size_t __hash(__type_name_t __v) _NOEXCEPT {
175 return reinterpret_cast<size_t>(__v);
176 }
177 _LIBCPP_INLINE_VISIBILITY _LIBCPP_ALWAYS_INLINE
178 static bool __eq(__type_name_t __lhs, __type_name_t __rhs) _NOEXCEPT {
179 return __lhs == __rhs;
180 }
181 _LIBCPP_INLINE_VISIBILITY _LIBCPP_ALWAYS_INLINE
182 static bool __lt(__type_name_t __lhs, __type_name_t __rhs) _NOEXCEPT {
183 return __lhs < __rhs;
184 }
185 };
186
187 struct __non_unique_impl : __string_impl_base {
188 _LIBCPP_INLINE_VISIBILITY _LIBCPP_ALWAYS_INLINE
189 static size_t __hash(__type_name_t __ptr) _NOEXCEPT {
190 size_t __hash = 5381;
191 while (unsigned char __c = static_cast<unsigned char>(*__ptr++))
192 __hash = (__hash * 33) ^ __c;
193 return __hash;
194 }
195 _LIBCPP_INLINE_VISIBILITY _LIBCPP_ALWAYS_INLINE
196 static bool __eq(__type_name_t __lhs, __type_name_t __rhs) _NOEXCEPT {
197 return __lhs == __rhs || __builtin_strcmp(__lhs, __rhs) == 0;
198 }
199 _LIBCPP_INLINE_VISIBILITY _LIBCPP_ALWAYS_INLINE
200 static bool __lt(__type_name_t __lhs, __type_name_t __rhs) _NOEXCEPT {
201 return __builtin_strcmp(__lhs, __rhs) < 0;
202 }
203 };
204
205 struct __non_unique_arm_rtti_bit_impl {
206 typedef uintptr_t __type_name_t;
207
208 _LIBCPP_INLINE_VISIBILITY _LIBCPP_ALWAYS_INLINE
209 static const char* __type_name_to_string(__type_name_t __v) _NOEXCEPT {
210 return reinterpret_cast<const char*>(__v &
211 ~__non_unique_rtti_bit::value);
212 }
213 _LIBCPP_INLINE_VISIBILITY _LIBCPP_ALWAYS_INLINE
214 static __type_name_t __string_to_type_name(const char* __v) _NOEXCEPT {
215 return reinterpret_cast<__type_name_t>(__v);
216 }
217
218 _LIBCPP_INLINE_VISIBILITY _LIBCPP_ALWAYS_INLINE
219 static size_t __hash(__type_name_t __v) _NOEXCEPT {
220 if (__is_type_name_unique(__v))
221 return reinterpret_cast<size_t>(__v);
222 return __non_unique_impl::__hash(__type_name_to_string(__v));
223 }
224 _LIBCPP_INLINE_VISIBILITY _LIBCPP_ALWAYS_INLINE
225 static bool __eq(__type_name_t __lhs, __type_name_t __rhs) _NOEXCEPT {
226 if (__lhs == __rhs)
227 return true;
228 if (__is_type_name_unique(__lhs, __rhs))
229 return false;
230 return __builtin_strcmp(__type_name_to_string(__lhs), __type_name_to_string(__rhs)) == 0;
231 }
232 _LIBCPP_INLINE_VISIBILITY _LIBCPP_ALWAYS_INLINE
233 static bool __lt(__type_name_t __lhs, __type_name_t __rhs) _NOEXCEPT {
234 if (__is_type_name_unique(__lhs, __rhs))
235 return __lhs < __rhs;
236 return __builtin_strcmp(__type_name_to_string(__lhs), __type_name_to_string(__rhs)) < 0;
237 }
238
239 private:
240 // The unique bit is the top bit. It is expected that __type_name_t is 64 bits when
241 // this implementation is actually used.
242 typedef std::integral_constant<__type_name_t,
243 (1ULL << ((__CHAR_BIT__ * sizeof(__type_name_t)) - 1))> __non_unique_rtti_bit;
244
245 _LIBCPP_INLINE_VISIBILITY
246 static bool __is_type_name_unique(__type_name_t __lhs) _NOEXCEPT {
247 return !(__lhs & __non_unique_rtti_bit::value);
248 }
249 _LIBCPP_INLINE_VISIBILITY
250 static bool __is_type_name_unique(__type_name_t __lhs, __type_name_t __rhs) _NOEXCEPT {
251 return !((__lhs & __rhs) & __non_unique_rtti_bit::value);
252 }
253 };
254
255 typedef
256#if defined(__APPLE__) && defined(__LP64__) && !defined(__x86_64__)
257 __non_unique_arm_rtti_bit_impl
258#elif _LIBCPP_HAS_MERGED_TYPEINFO_NAMES_DEFAULT == 0
259 __non_unique_impl
260#elif _LIBCPP_HAS_MERGED_TYPEINFO_NAMES_DEFAULT == 1
261 __unique_impl
262#else
263# error invalid configuration for _LIBCPP_HAS_MERGED_TYPEINFO_NAMES_DEFAULT
264#endif
265 __impl;
266};
267
268class _LIBCPP_EXCEPTION_ABI type_info
269{
270 type_info& operator=(const type_info&);
271 type_info(const type_info&);
272
273 protected:
274 typedef __type_info_implementations::__impl __impl;
275
276 __impl::__type_name_t __type_name;
277
278 _LIBCPP_INLINE_VISIBILITY
279 explicit type_info(const char* __n)
280 : __type_name(__impl::__string_to_type_name(__n)) {}
281
282public:
283 _LIBCPP_AVAILABILITY_TYPEINFO_VTABLE
284 virtual ~type_info();
285
286 _LIBCPP_INLINE_VISIBILITY
287 const char* name() const _NOEXCEPT
288 {
289 return __impl::__type_name_to_string(__type_name);
290 }
291
292 _LIBCPP_INLINE_VISIBILITY
293 bool before(const type_info& __arg) const _NOEXCEPT
294 {
295 return __impl::__lt(__type_name, __arg.__type_name);
296 }
297
298 _LIBCPP_INLINE_VISIBILITY
299 size_t hash_code() const _NOEXCEPT
300 {
301 return __impl::__hash(__type_name);
302 }
303
304 _LIBCPP_INLINE_VISIBILITY
305 bool operator==(const type_info& __arg) const _NOEXCEPT
306 {
307 return __impl::__eq(__type_name, __arg.__type_name);
308 }
309
310 _LIBCPP_INLINE_VISIBILITY
311 bool operator!=(const type_info& __arg) const _NOEXCEPT
312 { return !operator==(__arg); }
313};
314#endif // defined(_LIBCPP_ABI_MICROSOFT)
315
316class _LIBCPP_EXCEPTION_ABI bad_cast
317 : public exception
318{
319 public:
320 bad_cast() _NOEXCEPT;
321 virtual ~bad_cast() _NOEXCEPT;
322 virtual const char* what() const _NOEXCEPT;
323};
324
325class _LIBCPP_EXCEPTION_ABI bad_typeid
326 : public exception
327{
328 public:
329 bad_typeid() _NOEXCEPT;
330 virtual ~bad_typeid() _NOEXCEPT;
331 virtual const char* what() const _NOEXCEPT;
332};
333
334} // std
335
336#endif // defined(_LIBCPP_ABI_VCRUNTIME)
337
338_LIBCPP_BEGIN_NAMESPACE_STD
339_LIBCPP_NORETURN inline _LIBCPP_INLINE_VISIBILITY
340void __throw_bad_cast()
341{
342#ifndef _LIBCPP_NO_EXCEPTIONS
343 throw bad_cast();
344#else
345 _VSTD::abort();
346#endif
347}
348_LIBCPP_END_NAMESPACE_STD
349
350#endif // __LIBCPP_TYPEINFO
351