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 // FIXME: ABI detection should be done via compiler builtin macros. This 22 // is just a placeholder until Clang implements such macros. For now assume 23 // that Windows compilers pretending to be MSVC++ target the Microsoft ABI, 24 // and allow the user to explicitly specify the ABI to handle cases where this 25 // heuristic falls short. 26 #if _LIBCPP_ABI_FORCE_ITANIUM && _LIBCPP_ABI_FORCE_MICROSOFT 27 # error "Only one of _LIBCPP_ABI_FORCE_ITANIUM and _LIBCPP_ABI_FORCE_MICROSOFT can be true" 28 #elif _LIBCPP_ABI_FORCE_ITANIUM 29 # define _LIBCPP_ABI_ITANIUM 30 #elif _LIBCPP_ABI_FORCE_MICROSOFT 31 # define _LIBCPP_ABI_MICROSOFT 32 #else 33 # if defined(_WIN32) && defined(_MSC_VER) 34 # define _LIBCPP_ABI_MICROSOFT 35 # else 36 # define _LIBCPP_ABI_ITANIUM 37 # endif 38 #endif 39 40 #if _LIBCPP_ABI_VERSION >= 2 41 // Change short string representation so that string data starts at offset 0, 42 // improving its alignment in some cases. 43 # define _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT 44 // Fix deque iterator type in order to support incomplete types. 45 # define _LIBCPP_ABI_INCOMPLETE_TYPES_IN_DEQUE 46 // Fix undefined behavior in how std::list stores its linked nodes. 47 # define _LIBCPP_ABI_LIST_REMOVE_NODE_POINTER_UB 48 // Fix undefined behavior in how __tree stores its end and parent nodes. 49 # define _LIBCPP_ABI_TREE_REMOVE_NODE_POINTER_UB 50 // Fix undefined behavior in how __hash_table stores its pointer types. 51 # define _LIBCPP_ABI_FIX_UNORDERED_NODE_POINTER_UB 52 # define _LIBCPP_ABI_FORWARD_LIST_REMOVE_NODE_POINTER_UB 53 # define _LIBCPP_ABI_FIX_UNORDERED_CONTAINER_SIZE_TYPE 54 // Override the default return value of exception::what() for bad_function_call::what() 55 // with a string that is specific to bad_function_call (see http://wg21.link/LWG2233). 56 // This is an ABI break on platforms that sign and authenticate vtable function pointers 57 // because it changes the mangling of the virtual function located in the vtable, which 58 // changes how it gets signed. 59 # define _LIBCPP_ABI_BAD_FUNCTION_CALL_GOOD_WHAT_MESSAGE 60 // Enable optimized version of __do_get_(un)signed which avoids redundant copies. 61 # define _LIBCPP_ABI_OPTIMIZED_LOCALE_NUM_GET 62 // Give reverse_iterator<T> one data member of type T, not two. 63 // Also, in C++17 and later, don't derive iterator types from std::iterator. 64 # define _LIBCPP_ABI_NO_ITERATOR_BASES 65 // Use the smallest possible integer type to represent the index of the variant. 66 // Previously libc++ used "unsigned int" exclusively. 67 # define _LIBCPP_ABI_VARIANT_INDEX_TYPE_OPTIMIZATION 68 // Unstable attempt to provide a more optimized std::function 69 # define _LIBCPP_ABI_OPTIMIZED_FUNCTION 70 // All the regex constants must be distinct and nonzero. 71 # define _LIBCPP_ABI_REGEX_CONSTANTS_NONZERO 72 // Re-worked external template instantiations for std::string with a focus on 73 // performance and fast-path inlining. 74 # define _LIBCPP_ABI_STRING_OPTIMIZED_EXTERNAL_INSTANTIATION 75 // Enable clang::trivial_abi on std::unique_ptr. 76 # define _LIBCPP_ABI_ENABLE_UNIQUE_PTR_TRIVIAL_ABI 77 // Enable clang::trivial_abi on std::shared_ptr and std::weak_ptr 78 # define _LIBCPP_ABI_ENABLE_SHARED_PTR_TRIVIAL_ABI 79 // std::random_device holds some state when it uses an implementation that gets 80 // entropy from a file (see _LIBCPP_USING_DEV_RANDOM). When switching from this 81 // implementation to another one on a platform that has already shipped 82 // std::random_device, one needs to retain the same object layout to remain ABI 83 // compatible. This switch removes these workarounds for platforms that don't care 84 // about ABI compatibility. 85 # define _LIBCPP_ABI_NO_RANDOM_DEVICE_COMPATIBILITY_LAYOUT 86 // Don't export the legacy __basic_string_common class and its methods from the built library. 87 # define _LIBCPP_ABI_DO_NOT_EXPORT_BASIC_STRING_COMMON 88 // Don't export the legacy __vector_base_common class and its methods from the built library. 89 # define _LIBCPP_ABI_DO_NOT_EXPORT_VECTOR_BASE_COMMON 90 // According to the Standard, `bitset::operator[] const` returns bool 91 # define _LIBCPP_ABI_BITSET_VECTOR_BOOL_CONST_SUBSCRIPT_RETURN_BOOL 92 // Fix the implementation of CityHash used for std::hash<fundamental-type>. 93 // This is an ABI break because `std::hash` will return a different result, 94 // which means that hashing the same object in translation units built against 95 // different versions of libc++ can return inconsistent results. This is especially 96 // tricky since std::hash is used in the implementation of unordered containers. 97 // 98 // The incorrect implementation of CityHash has the problem that it drops some 99 // bits on the floor. 100 # define _LIBCPP_ABI_FIX_CITYHASH_IMPLEMENTATION 101 // Remove the base 10 implementation of std::to_chars from the dylib. 102 // The implementation moved to the header, but we still export the symbols from 103 // the dylib for backwards compatibility. 104 # define _LIBCPP_ABI_DO_NOT_EXPORT_TO_CHARS_BASE_10 105 // Define std::array/std::string_view iterators to be __wrap_iters instead of raw 106 // pointers, which prevents people from relying on a non-portable implementation 107 // detail. This is especially useful because enabling bounded iterators hardening 108 // requires code not to make these assumptions. 109 # define _LIBCPP_ABI_USE_WRAP_ITER_IN_STD_ARRAY 110 # define _LIBCPP_ABI_USE_WRAP_ITER_IN_STD_STRING_VIEW 111 // Dont' add an inline namespace for `std::filesystem` 112 # define _LIBCPP_ABI_NO_FILESYSTEM_INLINE_NAMESPACE 113 // std::basic_ios uses WEOF to indicate that the fill value is 114 // uninitialized. However, on platforms where the size of char_type is 115 // equal to or greater than the size of int_type and char_type is unsigned, 116 // std::char_traits<char_type>::eq_int_type() cannot distinguish between WEOF 117 // and WCHAR_MAX. This ABI setting determines whether we should instead track whether the fill 118 // value has been initialized using a separate boolean, which changes the ABI. 119 # define _LIBCPP_ABI_IOS_ALLOW_ARBITRARY_FILL_VALUE 120 // Historically, libc++ used a type called `__compressed_pair` to reduce storage needs in cases of empty types (e.g. an 121 // empty allocator in std::vector). We switched to using `[[no_unique_address]]`. However, for ABI compatibility reasons 122 // we had to add artificial padding in a few places. 123 // 124 // This setting disables the addition of such artificial padding, leading to a more optimal 125 // representation for several types. 126 # define _LIBCPP_ABI_NO_COMPRESSED_PAIR_PADDING 127 #elif _LIBCPP_ABI_VERSION == 1 128 # if !(defined(_LIBCPP_OBJECT_FORMAT_COFF) || defined(_LIBCPP_OBJECT_FORMAT_XCOFF)) 129 // Enable compiling copies of now inline methods into the dylib to support 130 // applications compiled against older libraries. This is unnecessary with 131 // COFF dllexport semantics, since dllexport forces a non-inline definition 132 // of inline functions to be emitted anyway. Our own non-inline copy would 133 // conflict with the dllexport-emitted copy, so we disable it. For XCOFF, 134 // the linker will take issue with the symbols in the shared object if the 135 // weak inline methods get visibility (such as from -fvisibility-inlines-hidden), 136 // so disable it. 137 # define _LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS 138 # endif 139 // Feature macros for disabling pre ABI v1 features. All of these options 140 // are deprecated. 141 # if defined(__FreeBSD__) && __FreeBSD__ < 14 142 # define _LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR 143 # endif 144 #endif 145 146 // We had some bugs where we use [[no_unique_address]] together with construct_at, 147 // which causes UB as the call on construct_at could write to overlapping subobjects 148 // 149 // https://github.com/llvm/llvm-project/issues/70506 150 // https://github.com/llvm/llvm-project/issues/70494 151 // 152 // To fix the bug we had to change the ABI of some classes to remove [[no_unique_address]] under certain conditions. 153 // The macro below is used for all classes whose ABI have changed as part of fixing these bugs. 154 #define _LIBCPP_ABI_LLVM18_NO_UNIQUE_ADDRESS __attribute__((__abi_tag__("llvm18_nua"))) 155 156 // Changes the iterator type of select containers (see below) to a bounded iterator that keeps track of whether it's 157 // within the bounds of the original container and asserts it on every dereference. 158 // 159 // ABI impact: changes the iterator type of the relevant containers. 160 // 161 // Supported containers: 162 // - `span`; 163 // - `string_view`. 164 // #define _LIBCPP_ABI_BOUNDED_ITERATORS 165 166 // Changes the iterator type of `basic_string` to a bounded iterator that keeps track of whether it's within the bounds 167 // of the original container and asserts it on every dereference and when performing iterator arithmetics. 168 // 169 // ABI impact: changes the iterator type of `basic_string` and its specializations, such as `string` and `wstring`. 170 // #define _LIBCPP_ABI_BOUNDED_ITERATORS_IN_STRING 171 172 // Changes the iterator type of `vector` to a bounded iterator that keeps track of whether it's within the bounds of the 173 // original container and asserts it on every dereference and when performing iterator arithmetics. Note: this doesn't 174 // yet affect `vector<bool>`. 175 // 176 // ABI impact: changes the iterator type of `vector` (except `vector<bool>`). 177 // #define _LIBCPP_ABI_BOUNDED_ITERATORS_IN_VECTOR 178 179 // Changes the iterator type of `array` to a bounded iterator that keeps track of whether it's within the bounds of the 180 // container and asserts it on every dereference and when performing iterator arithmetic. 181 // 182 // ABI impact: changes the iterator type of `array`, its size and its layout. 183 // #define _LIBCPP_ABI_BOUNDED_ITERATORS_IN_STD_ARRAY 184 185 // [[msvc::no_unique_address]] seems to mostly affect empty classes, so the padding scheme for Itanium doesn't work. 186 #if defined(_LIBCPP_ABI_MICROSOFT) && !defined(_LIBCPP_ABI_NO_COMPRESSED_PAIR_PADDING) 187 # define _LIBCPP_ABI_NO_COMPRESSED_PAIR_PADDING 188 #endif 189 190 // Tracks the bounds of the array owned by std::unique_ptr<T[]>, allowing it to trap when accessed out-of-bounds. 191 // Note that limited bounds checking is also available outside of this ABI configuration, but only some categories 192 // of types can be checked. 193 // 194 // ABI impact: This causes the layout of std::unique_ptr<T[]> to change and its size to increase. 195 // This also affects the representation of a few library types that use std::unique_ptr 196 // internally, such as the unordered containers. 197 // #define _LIBCPP_ABI_BOUNDED_UNIQUE_PTR 198 199 #if defined(_LIBCPP_COMPILER_CLANG_BASED) 200 # if defined(__APPLE__) 201 # if defined(__i386__) || defined(__x86_64__) 202 // use old string layout on x86_64 and i386 203 # elif defined(__arm__) 204 // use old string layout on arm (which does not include aarch64/arm64), except on watch ABIs 205 # if defined(__ARM_ARCH_7K__) && __ARM_ARCH_7K__ >= 2 206 # define _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT 207 # endif 208 # else 209 # define _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT 210 # endif 211 # endif 212 #endif 213 214 #endif // _LIBCPP___CONFIGURATION_ABI_H 215