[libcxx-commits] [libcxx] [libc++] [NFC] Split type_info header (PR #68812)
via libcxx-commits
libcxx-commits at lists.llvm.org
Wed Oct 11 12:23:12 PDT 2023
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-libcxx
Author: None (itrofimow)
<details>
<summary>Changes</summary>
This PR splits `type_info` header into public and private parts, with the purpose of simplifying https://github.com/llvm/llvm-project/pull/65534, which should be rebased onto this patch
---
Patch is 29.22 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/68812.diff
6 Files Affected:
- (modified) libcxx/include/CMakeLists.txt (+1)
- (added) libcxx/include/__typeinfo/typeinfo.h (+336)
- (modified) libcxx/include/libcxx.imp (+1)
- (modified) libcxx/include/module.modulemap.in (+5)
- (modified) libcxx/include/typeinfo (+1-353)
- (modified) libcxx/utils/data/ignore_format.txt (-1)
``````````diff
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index 4d98b8eed1afd65..bd4fb37d99834aa 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/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
diff --git a/libcxx/include/__typeinfo/typeinfo.h b/libcxx/include/__typeinfo/typeinfo.h
new file mode 100644
index 000000000000000..07b53af2b478588
--- /dev/null
+++ b/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
diff --git a/libcxx/include/libcxx.imp b/libcxx/include/libcxx.imp
index 3eb2aa849314824..f7e906e024f33a4 100644
--- a/libcxx/include/libcxx.imp
+++ b/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" ] },
]
diff --git a/libcxx/include/module.modulemap.in b/libcxx/include/module.modulemap.in
index 09184af2732c83f..b8885379fa7d525 100644
--- a/libcxx/include/module.modulemap.in
+++ b/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"
diff --git a/libcxx/include/typeinfo b/libcxx/include/typeinfo
index 59bc291454c3d90..e869cd5e6750787 100644
--- a/libcxx/include/typeinfo
+++ b/libcxx/include/typeinfo
@@ -57,365 +57,13 @@ public:
*/
#include <__assert> // all public C++ headers provide the assertion handler
-#include <__availability>
#include <__config>
-#include <__exception/exception.h>
-#include <__type_traits/is_constant_evaluated.h>
-#include <__verbose_abort>
-#include <cstddef>
-#include <cstdint>
+#include <__typeinfo/typeinfo.h>
#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 on...
[truncated]
``````````
</details>
https://github.com/llvm/llvm-project/pull/68812
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