1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
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___CONFIGURATION_ABI_H
11#define _LIBCPP___CONFIGURATION_ABI_H
12
13#include <__config_site>
14#include <__configuration/compiler.h>
15#include <__configuration/platform.h>
16
17#ifndef _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER
18# pragma GCC system_header
19#endif
20
21#if _LIBCPP_ABI_VERSION >= 2
22// Change short string representation so that string data starts at offset 0,
23// improving its alignment in some cases.
24# define _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
25// Fix deque iterator type in order to support incomplete types.
26# define _LIBCPP_ABI_INCOMPLETE_TYPES_IN_DEQUE
27// Fix undefined behavior in how std::list stores its linked nodes.
28# define _LIBCPP_ABI_LIST_REMOVE_NODE_POINTER_UB
29// Fix undefined behavior in how __tree stores its end and parent nodes.
30# define _LIBCPP_ABI_TREE_REMOVE_NODE_POINTER_UB
31// Fix undefined behavior in how __hash_table stores its pointer types.
32# define _LIBCPP_ABI_FIX_UNORDERED_NODE_POINTER_UB
33# define _LIBCPP_ABI_FORWARD_LIST_REMOVE_NODE_POINTER_UB
34# define _LIBCPP_ABI_FIX_UNORDERED_CONTAINER_SIZE_TYPE
35// Override the default return value of exception::what() for bad_function_call::what()
36// with a string that is specific to bad_function_call (see http://wg21.link/LWG2233).
37// This is an ABI break on platforms that sign and authenticate vtable function pointers
38// because it changes the mangling of the virtual function located in the vtable, which
39// changes how it gets signed.
40# define _LIBCPP_ABI_BAD_FUNCTION_CALL_GOOD_WHAT_MESSAGE
41// Enable optimized version of __do_get_(un)signed which avoids redundant copies.
42# define _LIBCPP_ABI_OPTIMIZED_LOCALE_NUM_GET
43// Give reverse_iterator<T> one data member of type T, not two.
44// Also, in C++17 and later, don't derive iterator types from std::iterator.
45# define _LIBCPP_ABI_NO_ITERATOR_BASES
46// Use the smallest possible integer type to represent the index of the variant.
47// Previously libc++ used "unsigned int" exclusively.
48# define _LIBCPP_ABI_VARIANT_INDEX_TYPE_OPTIMIZATION
49// Unstable attempt to provide a more optimized std::function
50# define _LIBCPP_ABI_OPTIMIZED_FUNCTION
51// All the regex constants must be distinct and nonzero.
52# define _LIBCPP_ABI_REGEX_CONSTANTS_NONZERO
53// Re-worked external template instantiations for std::string with a focus on
54// performance and fast-path inlining.
55# define _LIBCPP_ABI_STRING_OPTIMIZED_EXTERNAL_INSTANTIATION
56// Enable clang::trivial_abi on std::unique_ptr.
57# define _LIBCPP_ABI_ENABLE_UNIQUE_PTR_TRIVIAL_ABI
58// Enable clang::trivial_abi on std::shared_ptr and std::weak_ptr
59# define _LIBCPP_ABI_ENABLE_SHARED_PTR_TRIVIAL_ABI
60// std::random_device holds some state when it uses an implementation that gets
61// entropy from a file (see _LIBCPP_USING_DEV_RANDOM). When switching from this
62// implementation to another one on a platform that has already shipped
63// std::random_device, one needs to retain the same object layout to remain ABI
64// compatible. This switch removes these workarounds for platforms that don't care
65// about ABI compatibility.
66# define _LIBCPP_ABI_NO_RANDOM_DEVICE_COMPATIBILITY_LAYOUT
67// Don't export the legacy __basic_string_common class and its methods from the built library.
68# define _LIBCPP_ABI_DO_NOT_EXPORT_BASIC_STRING_COMMON
69// Don't export the legacy __vector_base_common class and its methods from the built library.
70# define _LIBCPP_ABI_DO_NOT_EXPORT_VECTOR_BASE_COMMON
71// According to the Standard, `bitset::operator[] const` returns bool
72# define _LIBCPP_ABI_BITSET_VECTOR_BOOL_CONST_SUBSCRIPT_RETURN_BOOL
73// Fix the implementation of CityHash used for std::hash<fundamental-type>.
74// This is an ABI break because `std::hash` will return a different result,
75// which means that hashing the same object in translation units built against
76// different versions of libc++ can return inconsistent results. This is especially
77// tricky since std::hash is used in the implementation of unordered containers.
78//
79// The incorrect implementation of CityHash has the problem that it drops some
80// bits on the floor.
81# define _LIBCPP_ABI_FIX_CITYHASH_IMPLEMENTATION
82// Remove the base 10 implementation of std::to_chars from the dylib.
83// The implementation moved to the header, but we still export the symbols from
84// the dylib for backwards compatibility.
85# define _LIBCPP_ABI_DO_NOT_EXPORT_TO_CHARS_BASE_10
86// Define std::array/std::string_view iterators to be __wrap_iters instead of raw
87// pointers, which prevents people from relying on a non-portable implementation
88// detail. This is especially useful because enabling bounded iterators hardening
89// requires code not to make these assumptions.
90# define _LIBCPP_ABI_USE_WRAP_ITER_IN_STD_ARRAY
91# define _LIBCPP_ABI_USE_WRAP_ITER_IN_STD_STRING_VIEW
92// Dont' add an inline namespace for `std::filesystem`
93# define _LIBCPP_ABI_NO_FILESYSTEM_INLINE_NAMESPACE
94// std::basic_ios uses WEOF to indicate that the fill value is
95// uninitialized. However, on platforms where the size of char_type is
96// equal to or greater than the size of int_type and char_type is unsigned,
97// std::char_traits<char_type>::eq_int_type() cannot distinguish between WEOF
98// and WCHAR_MAX. This ABI setting determines whether we should instead track whether the fill
99// value has been initialized using a separate boolean, which changes the ABI.
100# define _LIBCPP_ABI_IOS_ALLOW_ARBITRARY_FILL_VALUE
101// Make a std::pair of trivially copyable types trivially copyable.
102// While this technically doesn't change the layout of pair itself, other types may decide to programatically change
103// their representation based on whether something is trivially copyable.
104# define _LIBCPP_ABI_TRIVIALLY_COPYABLE_PAIR
105#elif _LIBCPP_ABI_VERSION == 1
106# if !(defined(_LIBCPP_OBJECT_FORMAT_COFF) || defined(_LIBCPP_OBJECT_FORMAT_XCOFF))
107// Enable compiling copies of now inline methods into the dylib to support
108// applications compiled against older libraries. This is unnecessary with
109// COFF dllexport semantics, since dllexport forces a non-inline definition
110// of inline functions to be emitted anyway. Our own non-inline copy would
111// conflict with the dllexport-emitted copy, so we disable it. For XCOFF,
112// the linker will take issue with the symbols in the shared object if the
113// weak inline methods get visibility (such as from -fvisibility-inlines-hidden),
114// so disable it.
115# define _LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS
116# endif
117// Feature macros for disabling pre ABI v1 features. All of these options
118// are deprecated.
119# if defined(__FreeBSD__) && __FreeBSD__ < 14
120# define _LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR
121# endif
122#endif
123
124// We had some bugs where we use [[no_unique_address]] together with construct_at,
125// which causes UB as the call on construct_at could write to overlapping subobjects
126//
127// https://github.com/llvm/llvm-project/issues/70506
128// https://github.com/llvm/llvm-project/issues/70494
129//
130// To fix the bug we had to change the ABI of some classes to remove [[no_unique_address]] under certain conditions.
131// The macro below is used for all classes whose ABI have changed as part of fixing these bugs.
132#define _LIBCPP_ABI_LLVM18_NO_UNIQUE_ADDRESS __attribute__((__abi_tag__("llvm18_nua")))
133
134// Changes the iterator type of select containers (see below) to a bounded iterator that keeps track of whether it's
135// within the bounds of the original container and asserts it on every dereference.
136//
137// ABI impact: changes the iterator type of the relevant containers.
138//
139// Supported containers:
140// - `span`;
141// - `string_view`.
142// #define _LIBCPP_ABI_BOUNDED_ITERATORS
143
144// Changes the iterator type of `basic_string` to a bounded iterator that keeps track of whether it's within the bounds
145// of the original container and asserts it on every dereference and when performing iterator arithmetics.
146//
147// ABI impact: changes the iterator type of `basic_string` and its specializations, such as `string` and `wstring`.
148// #define _LIBCPP_ABI_BOUNDED_ITERATORS_IN_STRING
149
150// Changes the iterator type of `vector` to a bounded iterator that keeps track of whether it's within the bounds of the
151// original container and asserts it on every dereference and when performing iterator arithmetics. Note: this doesn't
152// yet affect `vector<bool>`.
153//
154// ABI impact: changes the iterator type of `vector` (except `vector<bool>`).
155// #define _LIBCPP_ABI_BOUNDED_ITERATORS_IN_VECTOR
156
157#if defined(_LIBCPP_COMPILER_CLANG_BASED)
158# if defined(__APPLE__)
159# if defined(__i386__) || defined(__x86_64__)
160// use old string layout on x86_64 and i386
161# elif defined(__arm__)
162// use old string layout on arm (which does not include aarch64/arm64), except on watch ABIs
163# if defined(__ARM_ARCH_7K__) && __ARM_ARCH_7K__ >= 2
164# define _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
165# endif
166# else
167# define _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
168# endif
169# endif
170#endif
171
172#endif // _LIBCPP___CONFIGURATION_ABI_H
173