[libc++] [NFC] Split typeinfo header

libcxx/include/CMakeLists.txt

@@ -832,6 +832,7 @@ set(files
   __type_traits/underlying_type.h
   __type_traits/unwrap_ref.h
   __type_traits/void_t.h
+  __typeinfo/typeinfo.h
   __undef_macros
   __utility/as_const.h
   __utility/auto_cast.h

libcxx/include/__typeinfo/typeinfo.h

@@ -0,0 +1,336 @@
+// -*- 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_TYPEINFO_H
+#define _LIBCPP___TYPEINFO_TYPEINFO_H
+
+#include <__availability>
+#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:
+  _LIBCPP_AVAILABILITY_TYPEINFO_VTABLE
+  virtual ~type_info();
+
+  const char* name() const _NOEXCEPT;
+
+  _LIBCPP_INLINE_VISIBILITY bool before(const type_info& __arg) const _NOEXCEPT { return __compare(__arg) < 0; }
+
+  size_t hash_code() const _NOEXCEPT;
+
+  _LIBCPP_INLINE_VISIBILITY _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_INLINE_VISIBILITY 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_INLINE_VISIBILITY _LIBCPP_ALWAYS_INLINE _LIBCPP_CONSTEXPR static const char*
+    __type_name_to_string(__type_name_t __v) _NOEXCEPT {
+      return __v;
+    }
+    _LIBCPP_INLINE_VISIBILITY _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_INLINE_VISIBILITY _LIBCPP_ALWAYS_INLINE static size_t __hash(__type_name_t __v) _NOEXCEPT {
+      return reinterpret_cast<size_t>(__v);
+    }
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_ALWAYS_INLINE static bool
+    __eq(__type_name_t __lhs, __type_name_t __rhs) _NOEXCEPT {
+      return __lhs == __rhs;
+    }
+    _LIBCPP_INLINE_VISIBILITY _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_INLINE_VISIBILITY _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_INLINE_VISIBILITY _LIBCPP_ALWAYS_INLINE static bool
+    __eq(__type_name_t __lhs, __type_name_t __rhs) _NOEXCEPT {
+      return __lhs == __rhs || __builtin_strcmp(__lhs, __rhs) == 0;
+    }
+    _LIBCPP_INLINE_VISIBILITY _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_INLINE_VISIBILITY _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_INLINE_VISIBILITY _LIBCPP_ALWAYS_INLINE static __type_name_t
+    __string_to_type_name(const char* __v) _NOEXCEPT {
+      return reinterpret_cast<__type_name_t>(__v);
+    }
+
+    _LIBCPP_INLINE_VISIBILITY _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_INLINE_VISIBILITY _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_INLINE_VISIBILITY _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_INLINE_VISIBILITY 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;
+};
+
+class _LIBCPP_EXPORTED_FROM_ABI 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_INLINE_VISIBILITY explicit type_info(const char* __n) : __type_name(__impl::__string_to_type_name(__n)) {}
+
+public:
+  _LIBCPP_AVAILABILITY_TYPEINFO_VTABLE
+  virtual ~type_info();
+
+  _LIBCPP_INLINE_VISIBILITY const char* name() const _NOEXCEPT { return __impl::__type_name_to_string(__type_name); }
+
+  _LIBCPP_INLINE_VISIBILITY bool before(const type_info& __arg) const _NOEXCEPT {
+    return __impl::__lt(__type_name, __arg.__type_name);
+  }
+
+  _LIBCPP_INLINE_VISIBILITY size_t hash_code() const _NOEXCEPT { return __impl::__hash(__type_name); }
+
+  _LIBCPP_INLINE_VISIBILITY _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_INLINE_VISIBILITY 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_INLINE_VISIBILITY 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
+
+#endif // _LIBCPP___TYPEINFO_TYPEINFO_H

libcxx/include/libcxx.imp

@@ -48,6 +48,7 @@
   { include: [ "@<__thread/.*>", "private", "<thread>", "public" ] },
   { include: [ "@<__tuple/.*>", "private", "<tuple>", "public" ] },
   { include: [ "@<__type_traits/.*>", "private", "<type_traits>", "public" ] },
+  { include: [ "@<__typeinfo/.*>", "private", "<typeinfo>", "public" ] },
   { include: [ "@<__utility/.*>", "private", "<utility>", "public" ] },
   { include: [ "@<__variant/.*>", "private", "<variant>", "public" ] },
 ]

libcxx/include/module.modulemap.in

@@ -1270,6 +1270,11 @@ module std_private_debug_utils_strict_weak_ordering_check [system] {
   export std_private_type_traits_is_constant_evaluated
 }
 
+module std_private_typeinfo_typeinfo          [system] {
+  header "__typeinfo/typeinfo.h"
+  export *
+}
+
 module std_private_exception_exception        [system] { header "__exception/exception.h" }
 module std_private_exception_exception_ptr    [system] {
   header "__exception/exception_ptr.h"