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Discussion and development of the “Itanium” portable C++ ABI used by many major C++ implementations. – Itanium C++ ABI. The Itanium ABI (which GCC uses) may specify these things (as within specifying ranges) Most types’ size and alignment is specified in the Intel System V ABI. Virtual Table Layout General A virtual table (vtable) is a table of information used to dispatch virtual functions, to ac.

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Itanium C++ ABI

These virtual tables are for specific cases of virtual inheritance. In the various explanatory examples, we use Ret?

If the constructor throws an exception, call destructor for any already constructed elements, and rethrow the exception. The optional ” gs ” prefix on some of the productions indicates that the corresponding source construct name, new-expression, or delete-expression includes a global-scope qualifier e.

This entry point will expect that its this pointer points to the unique virtual V subobject of C.

However, in order to look up a method that a class may respond to would be tedious if all methods are represented in this fashion. The values of some construction virtual table entries will differ from the corresponding entries in either the main virtual table group for B or the virtual table group for B-in-D, primarily because the virtual bases of B will be at different relative offsets in a D object than in a standalone B object, as follows: The actual content of the return register is unspecified.

Application binary interface

A complete ABI, such as the Intel Binary Compatibility Standard iBCS[1] allows a program from one operating system supporting that ABI to run without modifications on any other such system, provided that necessary shared libraries are present, and similar prerequisites are fulfilled. None of the above, i. However, an implementation intending to support automatically thread-safe, one-time initialization as opposed to requiring explicit user control for thread safety may make use of the following API functions: The standard guarantees In the object where instantiated, the virtual table, any subobject construction virtual tables, and the VTT, are emitted in a COMDAT identified by the virtual table mangled name.


The virtual pointers in the secondary VTTs and virtual VTTs are used for subobject construction, and may always point to special construction virtual tables laid out as described in the following subsections. This decision is independent of whether its components have been substituted, so an implementation may optimize by considering large structures for substitution before their components.

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Thus the effect is that these virtual tables occur in inheritance graph order, excluding primary bases and virtual bases. For further information, consult Chapter 6. This article has multiple issues. Since the Fortran Standard requires ktanium module procedure names not conflict with other external abii, [6] compilers tend to use the module name and the procedure name, with a distinct marker in between.

This allows subroutines written in those languages to call, or be called by, existing Windows libraries using a calling convention itabium from their jtanium. The array elements and the cookie are all aligned naturally. Email Required, but never shown. It has the size, data size, and alignment of a class containing those two members, in that order. If there is no key function, it is emitted everywhere used. Following the primary virtual table of a derived class are secondary virtual tables for each of its proper base classes, except any primary base s with which it shares its primary virtual table.

To do so, we divide classes into several categories, based on their base class structure. Sign up using Facebook. In compiler construction, name mangling also called name itanjum is a technique used to solve various problems caused by the need to resolve unique names for programming entities in many modern programming languages. These additional cases would be exactly those where the function is overridden in the derived class, implying an additional thunk adjustment back to the original pointer.


If the result of the operator is implicitly converted to a known integer type, that type is used for the literal; otherwise, the type of std:: Without replication, there would be more cases where the this pointer would have to be adjusted to access a secondary virtual table prior to the call.

Construction order between linked objects is determined by the initialization ordering specified in the base ABI.

Although name mangling cc not generally required or used by languages that do not support function overloading such as C and classic Pascalthey use it in some cases to provide additional information about a function.

All substitutable components are so numbered, except those that have already been numbered for substitution. Parts 1 and 3 of a primary not secondary, i.

Name mangling

Please improve it by verifying the claims made and adding inline citations. Add notes about missed opportunities. The callee constructs the return value into this temporary. Note that if the key function is not declared inline in the class definition, but its definition later itaniuk always declared inline, it will be emitted in every object containing the definition.

Include construction vtable proposal. Describe the non- effect of virtual bases on the alignment of the non-virtual part of a class as the base of another class A