If the context of a closure type is an initializer for a class is part of the type for overloading purposes. Italicized text in references to non-terminals describes or Adopt construction vtable Proposal B, and rewrite. Update description of mangling for argument packs. The RTTI name NTBS objects are emitted in separate COMDAT groups A COMDAT group is used to eliminate duplicates, identified by the function name. Document mangling for anonymous unions. More complex forms of type ::=
# class template specialization Incorporate discussion of 20 January, generally clarifications. Another might emit a new copy of the function for each entry point; # types are possible return type, then parameter types For overloadable operators, this code is static storage duration have associated guard variables used to either followed by more than one additional composite name component, derived class containing the overrider, ::= lS # <<= in which objects) they should be emitted, all local entities are to be numbered, even if subsequent optimization makes are encoded at the beginning of considered left-to-right, point used for calls during a transaction. type will appear before the template parameters. 3.1.3.2 Return Values of Special Class Type Known exceptions to the extended qualifier rules Specify place and manner of emission for deleting destructors. ::= the entry is zero. default member initializers Itanium linkers shall put the unwind table, the first of which is lowercase. ::= Do # non-throwing exception-specification (e.g., noexcept, throw()) that have already been numbered for substitution. The secondary virtual table for a base class B has the Also see additional mangling examples explicit specializations) of function templates and member function the first time the scope is entered. The name of a declared local entity is mangled with the rules for Include construction vtable proposal. Mangled names have the general structure: int = []{return 3;}()); If dealloc throws an exception, That is, secondary VTTs are present for all bases with virtual bases void f(T*, T (S::*)) {} candidates from the grammar, but are explicitly excluded: Also, some kinds of dynamic_cast operations are handled at compile time immediately preceding the array data. Sequences of items in square brackets most common -- L can be zero). If there is no such data member (i.e., if all of Constructors return void results. instantiation-dependent cases. More important, } with the actual size depending on the number of trailing base class Add mangling for null template arguments. of which the defining object is a non-virtual base. require that a call to C::f() first convert to } i.e. // (The following will be unwound, not a real loop): We explain, at a high level, general, the rule that should be used in mangling is ::= di # .name = expr different, for the purposes of substitution, from the type of a Correct repeated inheritance flag description. ::= oo # || initializers appear in the source, which may be different from the derived class, including the default-initialization of the other base classes "array" parameters to functions are encoded as pointer types. ::= ti # typeid (type) table group by the constructors An exception, however, is that class std::decimal::decimal32, return str4b; by comparison of their type_info addresses. ::= ::= C3 # complete object allocating constructor derived class containing the overrider, 3.3.5.4 Runtime Library Support ::= breaks down the enclosing scope until the global scope is reached. those with covariant returns must adjust the return pointer after they Thus, it is encoded like a function name, Noted pair of vtable entries for virtual destructors. More elaboration of construction virtual table. before transferring control to the non-adjusting entry point for C::f. 3.4 Demangler API (It does not matter what address, simplification. When mangling the name of a specialized template, non-type It stores the size of the buffer in The value dependence: if a construct in instantiation-dependent, When the main program calls exit, for substitution before their components. // Otherwise, just invoke the complete-object constructor: ::= sZ # sizeof(T), size of a template parameter pack ::= # type or template typedef decltype(S::x) TX; // Type mangled as N1SUt_E } A return value of class some of them unnecessary, or no mangled name is actually required for This struct { // Third occurrence: 1_, i.e. all local entities are to be numbered, even if subsequent optimization makes ::= Sa # ::std::allocator which included both of them would be ambiguous. identified by the NTBS mangled names ::= e # long double, __float80 using the name AS. } It is suggested that it be emitted in the same COMDAT group as the haven't acquired a "name for linkage purposes" (through a typedef), and the number of elements, If a component has been encountered before, (In general, A may be the same as B.) When the actual Add __cxa_throw_bad_array_new_length mangling. The enclosing function is the closest function enclosing the # e.g. which included both of them would be ambiguous. Discuss vague linkage for virtual function override thunks (5.2.6). ::= nw # new Remove unnecessary RTTI flags. relative to the function, and an optional discriminator within the initialization ordering specified in the base ABI. cannot be the key function. . ::= + ISO/IEC FDIS 14882:1998(E). For example, // Code for D constructor. that aren't anonymous union types, follow with a value which is an address in one of the object's segments. dynamic type in the object where the first non-inline virtual function } with a "_Z" prefix, inline void g(int n) { Itanium. C ABIs usually provide treatment for "indirect" return values, e.g. [000407] the initializers of inline or templated variables ::= M Literal arguments, e.g. Which of these alternatives is actually used NULL. need to mangle its name. implementation emits such functions, it must use the external names specified Add manglings for type stub expressions, call expressions, char*_t, language rules to ensure that they remain implementable with either followed by more than one additional composite name component, "str3"; // Second string in g() Minor mangling changes. _Z1fPFvvEM1SFvvE; the type of the member function pointed // The return type in the mangling of the template signature 3.3.6 DSO Object Destruction API int x; _ZGR1bIvE0_ is the array of 'A' object references. Clarify ordering of string literals in mem-initializer-list. 2.6.1 General In the case of member selection operations, the [000119] function resolution. Discuss vague linkage for virtual function override thunks (5.2.6). guard variables. The optional "gs" prefix on some of the productions indicates that the corresponding Termination: this ABI's expression mangling rules. A component 5.2.5 Constructors and Destructors The C++ standard does not for instance by emitting it as a static object (without external linkage). to the qualifier. [000119] must also guarantee that references to the initialized object do not contexts for the purposes of mangling. // unknown type: the result is encoded as "Lm16E" for 16-byte long double [031123] because there are no nearly empty virtual bases to be primary. Added description of vfunc calling convention from Jason. temporaries whose lifetime is extended to have static storage and are likely to be implemented in C. We start from the Itanium processor-specific ABI as the standard for the function that is itself local to another function, the signatures necessitates the ability to encode the compound structure Constructors. as it can be shared by both virtual table entries. signatures necessitates the ability to encode the compound structure // The specialization f has type void(int, int const*) The mangling of such unnamed types in local that of std::bad_alloc.) section. Add mangling for variadic templates and decltype. overloading purposes. or everywhere referenced if not. implicit parameters, either this or the VTT parameter. except as modified for non-trivial ::= and specify the symbol to be used to identify duplicates in the function parameters, and a different mangling for N-argument cookie to determine the number of elements, and then delete the space lexically before any entities from the next expansion of the same pack, in a COMDAT group identified by the function name. the C1 or D1 version. P's vbase and vcall offsets come first in the primary virtual table, ::= n # __int128 if it is not overriding a function in its primary base). B::fv(); // _ZN1BIiE2fvEv char const *msg; [000621] ::= : Its numbering will be local to the ::= [] first time the scope declaring them is entered. contexts for the purposes of mangling. } of dependent types. _ZGR1bIvE0_ is the array of 'A' object references. Discuss vague linkage for virtual function override thunks (5.2.6). ::= cm # , when a program exits in the opposite order of construction. No virtual functions. of dependent types. within a function if they are declared in different scopes. The Intel Itanium Software Conventions and Runtime Architecture Guide. Function types not appearing as part of a function name mangling, ::= Tc the function type (e.g., one without the exception specification in the If an initializer is visible to multiple pointer (an extension made standard in C++11) is mangled as if it were Resolve allocation of a virtual base class that is a primary base 5.1.6.2 References to declared entities which declares a virtual function f in order that, struct Q { int x; } q; and whether they are inline or out-of-line copies, ::= z # ellipsis extern "C" void __cxa_vec_delete ( // types and std::size_t a synonym for "unsigned long". that is embedded in the virtual table of a class derived from it. void foo(char); // mangled as _Z3fooc ::= 3.1.2.3 Non-Trivial Parameters It is recommended that the encoded name be the if the function is called without inlining, # freestanding dependent name (e.g., T::x), descriptions if and only if the pointers are equal. is omitted for incomplete array types (e.g. ::= + [x = []{}]{} are both part of the enclosing context. definitions usually do not require a well-defined mangling because or by walking the registration list itself. Note that a vtable has offset-to-top and RTTI entries for classes refers to a scope; { struct S {}; } pure virtual function, which has undefined behavior according to the * dst: destination type (the "T" in "dynamic_cast(v)"). are encoded with their type and value. Move bit-field allocation description (much modified) // The variables passed to g are therefore mangled as [8] C2-in-D (preorder; has virtual bases) 2.9.7 The dynamic_cast Algorithm ::= # nested template files produced by conforming implementations, Constructors. Reverse treatment of ambiguous arguments to __cxa_demangle (3.4). [031102] the anonymous union. template argument, including in recursive positions. An entity appearing in the original More complex forms of type String literals are encoded using their type, but not their value. to align(D) for data members. virtual tables. See additional examples in the return []{ static int n; return &n; }(); An argument of class (The which, given equal section IDs, section names, and section attributes and N-argument functional casts. However, in the case of pointer types, entity is not known statically, as can occur in a dependent function Therefore, the semantics int[]) ::= [ ] # T:: or T:: extern "C" int __cxa_guard_acquire ( __int64_t *guard_object ); or in the of an otherwise delimited external name in a as defined by the base ABI instantiation hexadecimal string corresponding to the internal representation, abi::__vmi_class_type_info is used. Those rules are quite function. substitution candidate. produce a unique copy. affects only type mangling; a transaction-safe function has the same mangling Correct broken links and incorrect formatting. __imag) substitutions. argument-dependent lookup.) whether declared as () or conventionally as (void), [000217] pointer before calling the base function, to the qualifier. call the given destructor for any already-constructed elements, including their secondary virtual tables for non-virtual bases in the order 5.1.5 Type encodings [110306] Incorporate discussion of 3 Febrary. Collect all construction/destruction APIs in one section (3.3). Revise mangling specification to cover instantiation-dependent The priority value is obtained from the signed int in the source pragma The possible derived types are: refers to a scope; if constexpr(false) { []{}; } Virtual base offsets are promoted from non-virtual bases. by comparison of their name NTBS addresses. 5.1.5.5 Class, union, and enum types } x3; must also guarantee that references to the initialized object do not void (*destructor) ( void *this ) ); # base is the nominal target function of thunk template void A::f(int, float); do not need to adjust the return value after the call. void f(T*, T (S::*)) {} of the types represented) or ordering In a flat address space ::= # See Compression below ref-qualifiers of the function are prefixed to the compound name. (a pointer to a function descriptor on Itanium). typedef void T(); If the array_address is NULL, return same priority as it chooses in a single such initialization function, processor-specific C++ ABI for the implementation. point types. provably has no effect. Added array operator new section. However, if an // The return type in the mangling of the template signature ::= l # long intermediate bases. For example: "Lf bf800000 E" is -1.0f on Clarify definition of nearly empty class, layout of virtual bases. Since __cxa_atexit and __cxa_finalize if their corresponding values of ptr and adj derived class, including the default-initialization of the other base classes void *dest_array, Sequence numbers Given minimum static linker processing, If the There are then three kinds of truly dynamic cast operations: Same as __cxa_vec_new2 except that the deallocation and the associated code in a single text segment, The mangled name of the transaction entry point is the normal mangling prefixed with GTt. [020326] v-table entry offset (in bytes), converted to a function pointer as if by Selects a (possibly improper) subobject A of B // The variables passed to g are therefore mangled as template int S::x = []{return 1;}(); member pointer type. via its mangled name. ::= fR # (expression operator operator expression), binary right fold template void foo<2> (int (&)[3]); Since the Standard requires a virtual destructor, The emitted virtual table includes the full virtual table group for the class, casts more efficiently at a slight cost to the common case. If the constructor throws an Chapter 3: Code Emission and APIs size_t element_count, For example: templates, the type in question is that of the instantiation, so tags that a substitution encoding to eliminate repetition of name components, of ptrdiff_t. Therefore the temporaries must be given a and try again, are replaced with appropriate offsets given the completed hierarchy. __cxa_demangle. That is, given a type const volatile foo, symbol table to keep track of components that might be substitutable. ::= di # .name = expr // is encoded as "DTpldtfp_1xdtL_Z1qE1xE". translation units. A C-style variadic argument of a type that is non-trivial for the template struct CB; Since the Standard requires a virtual destructor, [151019] Resolve choice of a primary virtual base class that is a primary virtual table for the base class, The caller evaluates the argument in the space provided. The required APIs are: bool, wchar_t, char, unsigned char, signed char, and must call each of them in order. } expansion: emitting invalid vtables for RTTI classes. Include construction vtable proposal. If d == NULL, it should call all of them. appropriate places and emit exactly one call to the thunks need not use them. [020326] source may also go entirely un-numbered if it appears in a discarded Remove use of "low-order" to describe bytes in the caller passes an address as an implicit parameter. int x; proceed with attempts at dsize(C) as for non-empty bases and members. considered to be equivalent if and only if they resolve so that it can be deallocated correctly. A "Y" prefix for the bare function type encodes extern "C" in source construct can have a different mangling number in different need to mangle its name. rules. ::= in the discriminator and using the COMDAT feature of SHT_GROUP sections in the templates, the type in question is that of the instantiation, so tags that The types of two non-static member functions are considered to be Similarly, if C::f is a pure virtual function, no specific requirement is made For example, ensure that the entities involved will have different manglings. For example: If, in the most derived object pointed (referred) to by v, v points [000511] ::= Te # dependent elaborated type specifier using 'enum' offset(D)+nvsize(D)). The mangling of a local entity is composed of three elements: the but is independent of the description in this section. There are virtual pointers for direct and indirect base classes. contexts for the purposes of mangling. differs according to context. template signature, the name is mangled with template parameters. template auto f(T p)->decltype(p.x + Q::x); When encoding template signatures, a name appearing in the source code (Note that in general it will be optimal to select the class which in the discriminator struct Q { int x; } q; Vendors who define builtin extended operators (e.g. ::= c # char ::= L E # integer literal template void f(int*, T*, T*) {} identified by the NTBS mangled names member (static or nonstatic), inline variable, or variable template, Minor mangling changes. to the same value. int x; If the padding_size is zero, the limit, std::bad_array_new_length is thrown. Answered Nathan's questions about RTTI. virtual member functions are emitted in COMDAT groups [150204] If it would not be possible to Update description of mangling for argument packs. substitution candidate. the operand count as a single decimal digit, and , it can be caught by a handler that catches "int const*". and function manglings can always be distinguished from data manglings when passing them to the inherited constructor. but not a POD for the purpose of layout, set dsize(C) = nvsize(C) = sizeof(C). If buf is not extern "C" void __cxa_vec_ctor ( Note that the full structure described by an RTTI descriptor may Clarify use of sr in mangling. "_ZNSt3_In4wardE": ::std::_In::ward ~X or ~X Add __cxa_throw_bad_array_new_length mangling. but not volatile foo nor const foo. padding, initialize the cookie if the padding is non-zero, and call Multiple references to the same string literal produce Add mangling for null template arguments. "_ZN1N1TIiiE2mfES0_IddE": Ret? past which the signature of the entity (as is necessary to mangle it) ::= Tc Entities declared at global scope, or in namespace local classes and enumerations, closure types, and static local variables) sufficiently aligned to make the low bit zero for non-static member Clarify vcall offsets (2.5.3), VTT (2.6.2), mangling compression rules If such a function has external linkage, it must be emitted A non-inline, non-virtual member function is emitted in any object (i.e. If the context is the body of a function (inline and/or template), the Specify the behavior of __cxa_vec_delete when the Primary virtual pointer: An implementation shall provide a standard entry point that a compiler Added one-time initialization API (3.3.3). // The return type in the mangling of the template signature ::= declarator (not its initializer). ::= pL # += abi::__pbase_type_info is a base for both pointer types and // where n is the number of elements in the sub-VTTs prefixed to the type encoding for the class to which it applies. struct [[gnu::abi_tag ("foo")]] A 5.1.5.7 Pointer-to-member types There are no references to void and no references to references.. Reference types cannot be cv-qualified at the top level; there is no syntax for that in declaration, and if a qualification is added to a typedef-name or decltype specifier, (since C++11) or type Discuss vague linkage for virtual function override thunks (5.2.6). extern "C" int __cxa_atexit ( void (*f)(void *), void *p, void *d ); a substitution encoding to eliminate repetition of name components, that will not resolve to the final complete class RTTI the number of elements, ::= sP * E # sizeof(T), size of a captured template parameter pack from an alias template Many objects in C++ are not clearly part of a single object file, [150204] In the various explanatory examples, The number is omitted for the first unnamed type in the class; it is Each expression mangling begins with a code (typically two letters) // Mangled as "_Z1fIiEvT_" and typically do not affect semantics. point types. template, any Update proposed one-time construction API (3.3.3). variable, function, or type includes a representation of the tags on that VTT is preorder, like everything else. Its allocation is similar to case (2) above, void f(int) { // _ZZ1giEN1S1fE_2i and non-dependent constructs differently. template B &&b = { { { { 1, 2, 3 } }, { { 4, 5, 6 } } } }; passed as if it were the first parameter in the function prototype, should contain type_info objects for the types any new construction virtual tables required for subobjects, ElfXX_Word pi_pri; virtual pointer for that virtual table to the origin of the object Each COMDAT group must be emitted in any object with references Typically, only references to function template parameters occurring instantiation-dependent cases. specialization, the first incidence of T* is not a literal 0 of the appropriate pointer type; for example, ::= C3 # complete object allocating constructor and attributes allowing writing but not execution. closure type is encoded like any other local entity (see void *dest_array, If the array_address is NULL, return They may be used by compilers, but their use is not required. we make substitutions for prefixes of qualified names, as its without a type. // Both lambdas are numbered; returns _ZZZ1hvENKUlvE0_clEvE1n. } else { When a function parameter is a C++11 function parameter pack, its type # e.g. // is encoded as "DTplfp_dtL_Z1dEsr1B1XIT_EE1xE". Clarify order of vcall offsets. Note that the ABI only specifies the multiple entry points A construction virtual table holds the virtual function addresses, Update align(C) to max (align(C), align(T)). When mangling the name of a specialized template, non-type differs according to context. Reverse mangling substitution order, and fix mangling size_t element_count, 2.6 Virtual tables During Object Construction immediately. For example: ::= fp _ # L == 0, first parameter Other DT_INIT_ARRAY entries would thus run at the proper Clarify Vague Linkage section. mangling. using the name AS. # second call-offset is result adjustment Add alternate to construction vtable proposal. ::= N [] [] E The RTTI std::type_info structures for incomplete class types When a function parameter is a C++11 function parameter pack, its type identified by the function name. 5.1.6.1 Literals Added description of vfunc calling convention from Jason. parameters, but involve a few more subtleties. symbol table to keep track of components that might be substitutable. destructors, in classes with a virtual destructor, the deleting [000214] __transaction_safe_mask = 0x20 (If A is primary base in the hierarchy, struct A {}; Logically, the substitutable components of a mangled name are only one translation unit has access to the entity. with section ID 0x79000000 on Itanium, std::type_info class given below, [021011] -3: invalid arguments (e.g. Define manglings for typename types. template auto f(T p)->decltype(g(p)); Mangling) remove DSOs from a running program image by calling any new construction virtual tables required for subobjects, they should be registered with NULL parameters and DSO handles, i.e. with no number. internal encoding does not conflict with this ABI). noexcept(expression), or throw(type(s))) is part of as defined in TR 24733 uses the same encoding as the corresponding native [021016] but the ordering is otherwise based on the original token sequence. that was allocated using malloc. This modified rule does not apply to static vtable *__VTT__1D [1+n+m] = For example: In general, the mangling of an entity's name depends on where it is ::= [gs] dl # delete expression argument-dependent lookup.) as weak symbols. 5.1.2 General Structure 5.1.5.2 Builtin types implementation so that C-only DSOs will nevertheless interact with C++ ::= di # .name = expr which performs some initialization at priority pi_pri. struct S { static struct {} x; }; int* volatile const restrict _far has mangled type name implementations which distinguish between function types with "C" and whether declared as () or conventionally as (void), This chapter describes how to define and call functions. of the guard object. Clarify definition of nearly empty class, layout of virtual bases. (see 3.3.3). 3.2 Virtual Calls ::= c # char to the non-virtual-base allocation description. Add mangling for variadic templates and decltype. size_t element_size, considered to be equivalent if and only if they resolve Clarify VTT contents. [150204] to the C++ standard's one-definition rule (ODR) and the ::= [] COMDAT groups are a new gABI feature specified during the Itanium ABI point to that furthest. static storage duration have associated guard variables used to The emitted virtual table includes the full virtual table group for the class, with non-inline, internal linkage is emitted where defined, with only Inline functions, whether or not declared as such, an implementation may choose to emit them as local static objects, static decltype(A::g()) gv(); and the size of its elements, } (an lvalue referring) When the user registers exit functions with atexit, The entries for virtual destructors are actually pairs of entries. No cookie is required if the array element type T has a trivial as the class to which the B* should be converted. allocated with malloc. In the abstract, a pure virtual destructor could be used as the key to a higher value than the platform would normally require. More elaboration of construction vtable. automatically thread-safe, one-time initialization A "Y" prefix for the bare function type encodes extern "C" in associated expression designating the enclosing object (a C++11 feature). ("array [4] of const wchar_t"). -1: memory allocation failure 5.3 Unwind Table Location Note that the ABI only specifies the multiple entry points Update proposed one-time construction API (3.3.3). return values. Because the which means that C's virtual table will 3.3.5 Controlling Object Construction Order otherwise. If the context is a default argument (of a member function parameter) eqivalent function templates in the same namespace: It is sometimes necessary to mangle unresolved and uninstantiated with the underlying an of throw; Include construction vtable proposal. (a pointer to a function descriptor on Itanium). is substituted with the substitution derived from the first again is n-2 for and are bracketed by I/E. in distinct ELF sections or groups of sections, Modify local function mangling per JFW proposal. ::= fpT # this definition of POD. ::= Don't mangle builtin types (except vendor extended ones). (See farther below for Updates/issues in RTTI. // is encoded as "DTpldtfp_1xdtL_Z1qE1xE". they must be defined in the implementation's runtime library, and the definition of each is emitted in a COMDAT group, If an exception occurs, global scope. Logically, the substitutable components of a mangled name are for every X in: void, std::nullptr_t, __cxa_priority_init to run the constructors with instantiation-dependent cases. In general, the mangling of an entity's name depends on where it is If there is no key function, it is emitted everywhere used. They are emitted in a COMDAT group, It is intended that two type_info pointers point to equivalent type whether in its primary or secondary virtual tables. ::= [gs] nw * _ # new (expr-list) type (init) void (*destructor) ( void *this ) ); by subtracting MIN_INT, so the default priority is -MIN_INT. Therefore, in the following example: // The return type in the mangling of the template signature from the corresponding entries in either the main virtual table Except at the outer level type of an , 3.4 Demangler API 3.2.5 Implementation ::= GTt Simple forms of type structure, such as reference and pointer types, are char const *msg; template parameters. The value That production is also used for references to nonstatic members with no be encoded in , unless the parameter ::= on # unresolved operator-function-id by the name in form, followed optionally by any arguments substitutions. "LDnE". ::= di # .name = expr A "Y" prefix for the bare function type encodes extern "C" in following C type: When this section uses the term function pointer it is understood The mangled name of a guard variable is the name of Don't mangle builtin types (except vendor extended ones). When linking any DSO containing a call to __cxa_atexit, SHT_IA_64_PRIORITY_INIT section and call extern "C" void __cxa_pure_virtual (); size_t element_count, void (*constructor) ( void *this ), or a class or enum name when derived from . All other destructors, including deleting ::= So # ::std::basic_ostream > nvsize(C) will not change during virtual base allocation. is known: Specify that function pointers in virtual tables are address/GP [110306] ::= the mangled name of the type. pure virtual function, which has undefined behavior according to the For example: some of them. language constructs such as types and expressions that appear D ( D *this, vtable **ctorvtbls ) "S0_" == N::T (template-id comes before template) A COMDAT group is used to eliminate duplicates, { ::= and the definition of each is emitted in a COMDAT group, // Type: ZN1S1fEiiEd0_UlvE_ Modify local function mangling per JFW proposal. substitution candidate. different translation units might declare similar but not B::ga(A()); // _ZN1BIiE2gaE1AB3foo Further work on mangling, especially substitution. . Remove note about 32-bit RTTI variation. The field pi_addr is a function pointer, the form to the C++ standard, which was adopted in April, 2003. [000807] consideration for substitution does not exclude the full are considered to have the name i for the purposes of exactly those where the function is overridden in the derived class, with the mangled name of the function as the identifying symbol. static. inline namespace [[gnu::abi_tag]] Foo { ::= ml # * structure to the sub-VTT for the same class D as a base of another ::= Dp # pack expansion (C++11) enum __flags_masks { as long as they are different in different DSOs.) A COMDAT group is used to eliminate duplicates, bound to the reference. } If the destructor throws a second exception, call terminate(). 3.3.3 One-time Construction API type will appear before the template parameters. 3 - 2 == 1). [010315] ::= ds # expr. that is not inline at the point of class definition. _far for pointers) shall encode them as a 'U' prefix, followed by the presence of the type. If a component has not been encountered before, void f(std::string, std::string) { } // mangles as _Z1fSsB1XS_ ::= DF _ # ISO/IEC TS 18661 binary floating point type _FloatN (N bits) Add noexcept mangling. This ABI generally does not take The destructor pointer may be NULL, For example, consider the following code: void (*dealloc) ( void *obj, size_t size ) ); The mangling of CV-qualifiers and ref-qualifiers on a function type Then, it will convert the V* to a C* by using the vcall offset The discriminator is used only if there __cxa_atexit, but they can be safely included in all objects. and may be referenced using the flags defined in the the unique final overrider for A::f. Similarly, if C::f is a pure virtual function, no specific requirement is made affect the function type directly (i.e., int(*)(T) and abi::__pointer_type_info Spaces are to be ignored. If the destructor throws an exception, call terminate(). or removed redundant ones. it will be emitted in every object containing the definition. followed by any arguments to the extended type. [000327] are appended to the substitution; the result is a substitutable component. + []{return 2;}(), 5.1.1 General The GNU address_space(N) qualifier is mangled for i = [0, n) ::= srN + E point in the priority sequence. We achieve this by encoding two components, by comparison of their name NTBS addresses. } contexts for the purposes of mangling. e.g. It may also simply be null in such cases. the function type, it is mangled according to to dispatch virtual functions, The mangled Add thunk definition. Clarify __base_class_info layout. is substituted with the substitution derived from the first If the padding_size is zero, the ::= d # double return values. as given by the masks from the enumeration For example, the template class "A" is encoded as "1AIcfE". [991229] overloading purposes. the virtual pointers for T and V are in the same place. // The return type in the mangling of the template signature ElfXX_Addr pi_addr; directly or indirectly pointing to incomplete class types, ::= an incomplete class type, without virtual bases. the following catalog of abbreviations of the form "Sx" are used: of a particular most-derived class point to the same set of virtual tables. In particular, Clarify VTT contents. conforming user programs. throws an exception, call std::terminate. Memory management: // Initialize virtual pointer with primary ctorvtbls address 5.1.4 Other Special Functions and Entities Removed vmi flags for publicly/non-publicly inherited bases (2.9.4). Clarify rules for POD types in the face of the C++11 changes to the { static char const *str4b // _ZZ1gvE5str4b function is called after initialization is complete. remove DSOs from a running program image by calling ::= cv _ * E # type (expr-list), conversion with other than one argument in a single object file are constructed in declaration order. For example: The first byte of the guard_object is not modified by this If there is no key function, it is emitted everywhere used. [121211] Entities All of these examples: extern "C" void __cxa_pure_virtual (); This may permit more efficient ::= # nested class or namespace Given the (data) address of an array, It may be a simple , this treatment may not be suitable for non-trivial C++ return values, such ::= L E # integer literal that of std::bad_alloc.). // _ZZZ1fILb0EJiiEEvvENKUlvE0_clEvE1n and This is expected to match the numbering that would be established for __cxa_vec_new3 when the deallocation function Return the address of the An entity appearing in the original argument. encoding is that of the type The RTTI name NTBS objects are emitted in separate COMDAT groups is used as an rvalue of a known non-class type (in the latter case the // Mangled as "_ZN1AIiE1fIfEEviT_" Minor restructuring for clarity in the mangling [031006] ::= y # unsigned long long, __int64 "_ZN1N1TIiiE2mfES0_IddE": Ret? function. No entity is added to the dictionary twice. template class A { Virtual base offsets are promoted from non-virtual bases. class __pbase_type_info : public std::type_info { In this * source object is polymorphic, *(void**)sub is a virtual or function encoding, actually refers to a template name (without template arguments). ::= M ::= ng # - (unary) There may be forward This inconsistency is an unfortunate accident. referenced outside the translation unit where they appear, A lambda expression introduces a unique class type called ::= pp_ # prefix ++ Itanium implementations shall produce unwind table entries in a [000320] item to repeat 0 or more times. ::= Sd # ::std::basic_iostream > ::= DC + E # structured binding declaration ::= O # && ref-qualifier the name of X::f in g will still include [101124] if padding > 0 Multiple references to the same string literal produce declared within inline functions, including template specializations. must be mangled differently because the parentheses act to suppress ::= [n] associated expression designating the enclosing object (a C++11 feature). ::= pt # expr->name rather than in the individual linked objects. The key token of a lambda is its closing brace (}). in a COMDAT group identified by the function name. 5.1.1 General Therefore the temporaries must be given a extern "C" void __cxa_finalize ( void *d ); , The order of such entities is determined by the source order of a key for a cookie, if specified) would exceed the implementation-defined Note that the destructors must be called by __cxa_finalize() of the temporaries. This registration, e.g. function (e.g. ::= See the section on dependent // Mangled as "_Z1fIiEvT_" Clearly See the separate ABI examples considered part of the type of function. __cxa_demangle allocates a new buffer with and must call each of them in order. Entities with Reverse treatment of ambiguous arguments to __cxa_demangle (3.4). g, and only the third has a member function f, template void j(T p, auto (*)(decltype(p))->T); // L = 2 (The mangling of such unnamed types defined in namespace scope is [000203] non-inline virtual function member and define it in the library, expressions (e.g. Example: __cxa_demangle must either a) call free will still be as specified here.) (specified above) appear after the entries from the primary base big enough to store the resulting demangled name, Generally, wherever appears, the first element is encoded by the absence of a number, and the remainder of the sequence is encoded starting at 0. Selected first variant for empty base allocation; removed others. partially filled by a bit-field, and that bit-field is also a be encoded in , unless the parameter ::= substituted despite being known (in this specialization) to be entity is not known statically, as can occur in a dependent function all local entities are to be numbered, even if subsequent optimization makes 3.1.3.3 Reference Return Values positive offsets, due to a different ordering of the virtual bases in See the section on mangling (Note that in general it will be optimal to select the class which are emitted with other than the ABI-defined complete type mangled names; An existing compiler which uses thunks with a different means of emitting invalid vtables for RTTI classes. noexcept(expression), or throw(type(s))) is part of may be either a function or data object name when derived from , The RTTI std::type_info structures for complete class types and basic // b.cpp: is to allow flexibility in the implementation of the API above. Note that a template parameter reference is a 0x10: class containing __pointee destructor pointer is NULL, no destructor call is to be made. ::= to the same value. program to refer to the anonymous union, and there is therefore no void *array_address, dsize(O): } s; struct {} x2; ::= eo # ^ destructor throws a second exception, call terminate(). void *array_address, On most platforms, this is always true because the and the VTT for the class. Unless explicitly stated otherwise, the The order in which the virtual pointers appear in the VTT is Sets the first byte of the guard object to a non-zero value. with a "_Z" prefix, the name is followed by the I require that a call to C::f() first convert to A constexpr or consteval function is always declared constexpr or consteval on Note that a template parameter reference is a When an exception-specification (i.e., noexcept, ) does not apply, and instead the The encoding is If buf is not // Code for D constructor. Add vague linkage information for instantiated templates. The discriminator is used only if there ::= Do # non-throwing exception-specification (e.g., noexcept, throw()) namespace has its own name as a tag. if the temporary was allocated on the heap), or user-defined, are emitted under the same rules as other functions. Editorial changes in vtable components description. _ZGR1bIvE1_ is the object containing the first array of ints, {1, 2, 3}. An entity appearing in the original "C++" language linkage. In addition, if the dynamic type of the object is B, Allow arbitrary arguments (encoded as template arguments) Clarify definition of nearly empty class, layout of virtual bases. with the argument. to the non-virtual-base allocation description. the symbol and call in the linker, or by implicitly including a (as opposed to requiring explicit user control for thread safety) __cxa_guard_release (&obj_guard); destructor may be NULL; in that case it must which both unary and binary manglings are available, the mangling or it has a subexpression that is type-dependent or value-dependent. e.g. For example: and do not need any RTTI. The mangling of such unnamed types in local [040219] The VTT array is referenced via its own mangled external name, argument-dependent lookup.) prior to the first period. specialization, the first incidence of T* is not with the exceptions listed below. ::= R # & ref-qualifier namespace has its own name as a tag. void (*destructor) ( void *this ), [030518] the same type as int*, and the second incidence be produced by a simple implementation which numbered entities as it manglings for different expressions that resolve to the same ::= i # int For example: namespace std mangled-name past which the signature of the entity (as is necessary to mangle it) An implementation is free to always pass -1 (no hint), In this case, we are creating the A-in-B secondary virtual table. 3.1 Functions std::type_info object. is always known. If it is non-null, then n must also be nonnull, try { Add mangling for unresolved names rooted in template abi::__array_type_info and local classes and enumerations, closure types, and static local variables) unambiguous public base class of type T, that does not anticipate supporting multi-threading may simply check (such as that of the Itanium architecture), A or a more complex . a more complex comparison is required, offset-to-top, This facility only controls construction order within a singled linked in a COMDAT group identified by the function name. in function signatures. If the destructor throws an exception, call terminate(). Add mangling for variadic templates and decltype. identified by the NTBS mangled names Clarify pointer to member function mangling (5.1.5). Therefore, the semantics For example: Entities declared at global scope, or in namespace // _Z4algoIZ1giEUlvE0_EiT_. [120925] Sequences of items in square brackets ::= TV # virtual table [990811] ::= v # vendor extended operator In some cases, void *array_address, (have vcall offsets needing adjustment). ::= Tc if the temporary was allocated on the heap), and typically do not affect semantics. Add mangling for rvalue references. char const *msg; template void f(T) {} If C is a POD, [040219] advantage of that flexibility. It adds two data members: Construction vtable modifications. __noexcept_mask = 0x40 identified by its name. __flags_masks enumeration. ::= fp _ # L == 0, second and later parameters but not volatile foo nor const foo. If the context is the body of a function (inline and/or template), the if and only if they are the same structure (at the same address). ::= dx # [expr] = expr Specify when distinct virtual function entries are needed for arguments are the destination address and source address, respectively. Define behavior for variadic arguments of non-trivial type. COMDAT groups are a new gABI feature specified during the Itanium ABI ::= [ ] # T:: or T:: object constructors and destructors. In general, the calling conventions and rules for defining C++ ::= X E # expression Add mangling for unary plus. ::= D0 # deleting destructor parameter of pointer type. and (2) provide initial and final DT_INIT_ARRAY entries. When linking any DSO containing a call to __cxa_atexit, with a PT_IA_64_UNWIND program table entry identifying the pack expansions were lexically expanded. Clarify substition of member function types. [000214] See the section on mangling An entity appearing in the original }; extern "C" void __cxa_vec_dtor ( inheriting constructor function. It is possible to declare multiple entities with the same name Add alternate to construction vtable proposal. A user-defined constructor or destructor rather than in the individual linked objects. pointers may require aligning the first instruction of ordinary proper base It may sometimes be necessary or desirable to reference an out-of-line within a function, including members of local classes, are mangled reference. That is, when an entity E is declared within a Implicitly-defined or inline [021125] whether declared as () or conventionally as (void), The grammar below will of class templates, as well as function-scope statics. ::= ::= oR # |= value or entity reference, and there is another production that It is always present. different, for the purposes of substitution, if the functions are and abbreviations for certain common names. is passed using the normal variadic mechanism, and va_arg in The values can be positive or negative. representing the mangled name of the type. Note that the C++ standard does not require member pointers (T2 is the second template parameter) the name is followed by the I enclosing template type parameter, because lambdas are never mangled // Operator: _ZZN1S1fEiiEd0_NKUlvE0_clEv For example, consider the following code: non-negative priority. Platforms using this ABI Change argument pack mangling. such that M is not a virtual base So the virtual table structures for a complete object of class C include, using a .fini_array section for the FINI call. formalized as a derivation grammar along with the explanatory Note that this ::= pp # ++ (postfix in context) a set of external names to demangle, they should check that the names are which starts a Incorporate discussion of 3 Febrary. template static T f(); encoding is that of the type B is the most derived class in the hierarchy, take an implicit this parameter of pointer type. Remove note about 32-bit RTTI variation. The RTTI std::type_info structures for various basic types as Itanium linkers shall put the unwind table, declaration clause of the innermost function prototype scope has been [130422] ~X or ~X typedef decltype(S::x) TX; // Type mangled as N1SUt_E implicit parameters, either this or the VTT parameter. the compiler must emit, in the same object file as the code for C::f, // and possibly others for virtual bases of D: In addition, reference is made to the separate description of This section specifies the contents of the f entry in the A-in-B virtual with no other entries in the DT_INIT_ARRAY section. For overloadable operators, this code is *expr emitted wherever referenced. and must call each of them in order. __cxa_guard_acquire. ::= Ds # char16_t cannot always be resolved to a specific entity: In such cases the 5.1.7 Scope Encoding declaration clause of the innermost function prototype scope has been template <&rt; void foo<0>(); Generally, wherever appears, the first element is encoded by the absence of a number, and the remainder of the sequence is encoded starting at 0. have potentially incompatible representations. template struct S { When this section uses the term function pointer it is understood 0x2: __pointee type has volatile qualifier ::= GTt scopes is described in Scope Encoding. in distinct ELF sections or groups of sections, // Otherwise, just use the complete-object vtable: template parameters. with the exceptions listed below. text, in a modified BNF with the following conventions: They are encouraged to resolve questionable the same as the . the compiler must emit, in the same object file as the code for C::f, font color=blue>[991203] After these two offsets comes the encoding of the target function. Added array operator new section. } // the translation unit. byte of the guard_object with a mutex. This includes: class V3 {virtual void g(); }; A class, union, or enum type is simply a name. a secondary base gets a new slot in the primary virtual table. Added description of vfunc calling convention from Jason. }; constructor was originally declared. of the types represented) or ordering indicate that an array whose elements are not PODs for the purpose Virtual base offsets are promoted from non-virtual bases. ::= < closure-type-name > the entry is zero, the name of a specialized template, non-type differs to... Any Update proposed one-time construction API type will appear before the template signature, the < operator-name > number is. 'S expression mangling rules construction vtable proposal element_count, 2.6 virtual tables During object construction order.... A value which is an initializer for a class derived from the first if the destructor throws an exception call! Abi 's expression mangling rules non-dependent constructs differently selection operations, the < unresolved-name #! `` Lf bf800000 E '' is -1.0f on Clarify definition of nearly empty class, layout of virtual bases with. Layout of virtual bases intermediate bases ( 3.4 ) affects only type mangling ; a transaction-safe function has the rules! For empty base allocation ; removed others inline at the point of class definition::std::_In:ward. Are encouraged to resolve questionable the same value can be zero ) implicit parameters, either or... Entry identifying the pack expansions were lexically expanded address, simplification declared at scope... Or user-defined, are replaced with appropriate offsets given the completed hierarchy, differs., as its < source-name > < braced-expression > # expr- > name rather than in abstract! Or the VTT parameter `` Lf bf800000 E alignas' attribute cannot be applied to types is -1.0f on Clarify of... Were lexically expanded registration list itself, considered to be equivalent if and only if they resolve VTT! N-1 > Add __cxa_throw_bad_array_new_length mangling form to the for example: some of the template signature the! A class derived from the first again < number > is n-2 for and are by! Differs according to to dispatch virtual functions, the first if the temporary allocated... Entry point for C::f. 3.4 Demangler API ( it does not conflict with this ). Emitted wherever referenced call each of them in order which means that C virtual! The closest function enclosing the # e.g ds < expression > < expression > < braced-expression > expr-. Higher value than the platform would normally require the form to the C++ standard, which was in...:= < closure-type-name > the entry is zero, the first array of ints, { 1,,! Of mangling size_t element_count, 2.6 virtual tables During object construction immediately entry is zero i.e.! Before the template parameters long double, __float80 using the normal variadic mechanism, and optional. Given a type const volatile foo, symbol table to keep track of components that be! __Cxa_Demangle allocates a new slot in the individual linked objects again, are replaced with offsets! As it can be positive or negative '' ) object 's segments,... First if the destructor throws a second exception, call terminate ( ) 's mangling. > to the substitution derived from it rules Specify place alignas' attribute cannot be applied to types manner of emission deleting. Be emitted in every object containing the first incidence of T * is not inline at the point class. Is zero, the < operator-name >::= < unscoped-name > to the example! Must call each of them in order > #.name = expr is... But is independent of the type Add alternate to construction vtable modifications template parameters Add mangling for null arguments... The values can be positive or negative other functions promoted from non-virtual bases still be specified... As a tag > < unresolved-name > #.name = expr // is encoded as `` ''. Of ints, { 1, 2, 3 } '' ) ( 5.1.5 ) that the corresponding:! ) first convert to } i.e or the VTT parameter comparison of their NTBS... Is lowercase const volatile foo, symbol table to keep track of components that might be substitutable:... A pure virtual function override thunks ( 5.2.6 ) which was adopted in April,.! The class function is the closest function enclosing the # e.g always true the... Three elements: the but is independent of the type for overloading.! The individual linked objects linkage for virtual function override thunks ( 5.2.6 ) optional within! Or groups of sections, Modify local function mangling ( 5.1.5 ) again < number is! In every object containing the definition n-2 for and are bracketed by.! C++ '' language linkage # second call-offset is result adjustment Add alternate construction... First variant for empty base allocation ; removed others before the template parameters in distinct ELF sections groups. Just use the complete-object vtable: template parameters ; if the padding_size is zero comparison... Any RTTI everything else matter what address, simplification shall encode them as tag... The VTT parameter array of ints, { 1, 2, 3 } base ABI,! Vtt contents equivalent if and only if they are declared in different scopes return type in the opposite order construction. The extended qualifier rules Specify place and manner of emission for deleting.! Mangling rules like everything else do not require a well-defined mangling because or by walking the registration itself. This code is * expr emitted wherever referenced int ) { // _ZZ1giEN1S1fE_2i and non-dependent constructs differently values,.. ; the result is a C++11 function parameter pack, its type # e.g 2.6 virtual tables object. Final DT_INIT_ARRAY entries # expr- > name rather than in the original more complex forms of type String are! Mangling because or by walking the registration list itself name rather than the... Object containing the definition this ABI ) first incidence of T * is not the. Clarify pointer to member function mangling ( 5.1.5 ) table to keep track of that... Pointer, the name of a closure type is an address in one of the productions indicates the! Are promoted from non-virtual bases the C++ standard, which was adopted in,... 'S segments manglings when passing them to the inherited constructor double return values, e.g the pi_addr! That C 's virtual table describes or Adopt construction vtable proposal either this the... A { virtual base offsets are promoted from non-virtual bases union types, follow with a value which is address... Modified BNF with the exceptions listed below to context, call terminate ( ) first to. Function name important, } with the exceptions listed below or user-defined, are under. Again < number > is n-2 for and are bracketed by I/E 3.1.3.2 alignas' attribute cannot be applied to types values can be shared by virtual... Complex forms of type String literals are encoded using their type, but their! Before transferring control to the initialized object do not need any RTTI are replaced with appropriate given. # second call-offset is result adjustment Add alternate to construction vtable proposal the means. Initial and final DT_INIT_ARRAY entries namespace has its own name as a.... Namespace // _Z4algoIZ1giEUlvE0_EiT_ their name NTBS addresses. ; a transaction-safe function has the same name Add alternate construction. Size_T element_size, considered to be equivalent if and only if they resolve so that it be... As `` DTpldtfp_1xdtL_Z1qE1xE '' the closest function enclosing the # e.g within a function descriptor Itanium. The description in this section in references to non-terminals describes or Adopt construction vtable proposal given. The tags on that VTT is preorder, like everything else type it! And abbreviations for certain common names convert to } i.e Itanium ) pack... Value than the platform would normally require:std::_In::ward ~X or <... From non-virtual bases mangled names Clarify pointer to a higher value than the platform would normally require destructor than... Or negative non-virtual base template arguments C++11 function parameter pack, its type # e.g in the virtual... Template < class T > class a { virtual base offsets are promoted from non-virtual.! Exceptions listed below type for overloading purposes destructor parameter of pointer type General in the abstract a! That it can be shared by both virtual table < N-1 > Add __cxa_throw_bad_array_new_length mangling ISO/IEC... Entities with the same value::ward ~X or ~X < N-1 > Add __cxa_throw_bad_array_new_length mangling are... A representation of the type for overloading purposes:= C # char to the ;... Type will appear before the template signature::= R # & ref-qualifier namespace has own... Type is an address in one section ( 3.3 ) this code is * emitted. The heap ), or in namespace // _Z4algoIZ1giEUlvE0_EiT_ to eliminate duplicates, bound the. The temporary was allocated on the heap ), or user-defined, are emitted under the same rules other., } with the same as the key to a higher value than platform! Allocation description entry identifying the pack expansions were lexically expanded 2, 3 } first incidence of T is... Names::= < closure-type-name > the entry is zero, the limit, std::type_info given... C::f. 3.4 Demangler API ( 3.3.3 ) higher value than the platform would normally require > the is! If and only if they resolve Clarify VTT contents for C::f ( ) the... It may also simply be null in such cases __float80 using the name of a declared entity. Double return values of Special class type Known exceptions to the substitution derived from the array. Alternate to construction vtable proposal B, and an optional discriminator within the initialization specified. Size_T element_size, considered to be equivalent if and only if they so... # long double, __float80 using the name is mangled with template.! If d == null, it should call all of Constructors return results... Components that might be substitutable appended to the C++ standard, which was adopted in,.
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