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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There is no standard itanum of whether the restrict attribute is part of the type for overloading purposes. 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. The SEL value for a selector does not vary between classes.

c++ – To what extent does the Itanium ABI really specify padding and alignment? – Stack Overflow

All other characters are terminals, representing themselves. You can help by adding to it. Most implementations have handled this by calling the C library atexit routine to register the destructors. Unlike Cfront, unary and binary operators using the same symbol have different encodings. This page was last edited on 17 June wbi, at In cases where multiple order-insensitive qualifiers are present, they should be ordered ‘K’ closest to the base type’V’, ‘r’, and ‘U’ farthest ittanium the base typewith the ‘U’ qualifiers in alphabetical order by the vendor name with alphabetically earlier names closer to the base type.


Type bool has size and alignment 1. Abbi outstanding questions list, and clean up questions in text. Space is allocated by the caller for the temporary. So the virtual table structures for a complete object of class C include, in no particular order: Where structured data layout is described, we generally assume Itanium psABI member sizes.

Clarify vcall offsets 2. Further, requiring a particular form of mangling would cause issues for systems where implementation limits e. Primary virtual bases require a secondary virtual pointer in the VTT because the derived class with which they will share a virtual pointer is determined by the most derived class in the hierarchy.

If D is a possibly unnamed bitfield whose declared type is T and whose declared width is n bits: See the description of these terms in General above. If D is a base class, this step allocates only its non-virtual part, i. Application binary interface ABI.

Text beginning with ‘ ‘ is comments, to be ignored. Occasionally entities in local scopes must be mangled too e. To ensure that the virtual table pointers are set to the appropriate virtual tables during proper base class construction, a table of virtual table pointers, called the VTT, which holds the addresses of construction and non-construction virtual tables itanuum generated for the complete class.

Multiple references to itanikm same string literal produce one string object with one name in the sequence. This section needs expansion.

It also includes function calling interfaces, exception handling interfaces, global naming, and various object code conventions. It holds the following function pointer entries, following those of any primary base’s virtual table, in the virtual functions’ declaration order: If it does so, the cost of this scheme, when run single-threaded with minimal versions of the above functions, will be two extra function calls, each of them accessing the guard variable, the first time the scope is entered.


Will give it a read when I have a spare few months: Round sizeof C up to a non-zero multiple of align C.

The itaniym are substantively different if B is a morally virtual base of D or if B is not located at offset zero in D. Therefore, an implementation should include at least one non-inline virtual function member and define it in the library, to avoid having user code inadvertently preempt the virtual table. The use of the word “exact” in the quote is exaggeration.

Application binary interface

The virtual function overrides a function or functions appearing in the virtual table, but the return type of the overrider is substantively different from the return type of the function s already present. Which of these alternatives is actually used is specified elsewhere in the ABI, but is independent of the description in this section. The class has a virtual table for each virtual base class that has a virtual table.

We call the collection consisting of a primary virtual table along with all itankum its secondary virtual tables a virtual table group.