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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Managing selectors is more efficient than manipulating the textual representation of a method. Update proposed object construction priority API 3.

In such a case, the function is to be emitted in each object where its name is referenced. Empty classes passed as ordinary classes 3. The first is the constant adjustment to the nearest virtual base of the full objectof which the defining object is a non-virtual base. However, since construction virtual table groups may be organized differently see belowan implementation may not depend itannium this relationship between secondary virtual tables.

Application binary interface

Derived classes which override these functions may use the slots to determine the adjustment necessary. You need to follow the documentation to the standards incorporated by reference. Therefore, this ABI does not specify its behavior, but it is expected that it will terminate the program, possibly itaniuj an error message. For example, dynamic linking is avoided to allow smaller executables and faster loading, fixed register usage allows more compact stacks and kernel calls, and running the application in privileged mode allows direct access to custom hardware operation without the indirection of calling a device driver.

The order of the virtual function pointers in a virtual table is the order of declaration of the corresponding member functions in the class. 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 aib necessary shared libraries are present, and similar prerequisites are fulfilled.


Classloaders are ordered hierarchically and each Thread in the JVM has a so-called context class loader, so in cases where two different classloader instances contain classes with the same name, the system first tries to load the class using the root or system classloader and then goes down the hierarchy to the context class loader.

Any indirect primary base class E of the current class C, i.

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

Some objects with static storage duration have associated guard variables used to ensure that they are initialized only once see 3. Identifiers in Fortran 90 modules must be further mangled, because the same procedure name may occur in different modules.

Will give it a read when I have a spare few months: In addition, if the dynamic type of the object is B, then C:: For other uses, see Name conflict. If the constructor throws an exception, call destructor for any already constructed elements, and rethrow the exception. Compilers that support the EABI create object code that is compatible with code generated by other such compilers, allowing developers to link libraries generated with one compiler with object code generated with another compiler.

They are used to find the necessary adjustment from the virtual base to the derived class containing the overrider, if any. No inherited virtual functions. It was thought that 2b would allow the compiler to avoid adjusting this in some cases, but this was incorrect, as the virtual function call algorithm requires that the function be looked up through a pointer to a class that defines the function, not one that just inherits it.


If a component has not been encountered before, its mangling is identified, and it is added to a dictionary of substitution candidates. Adhering to itanum ABI itanimu may or may not be officially standardized is usually the job of a compileroperating system, or library author; however, an application programmer may have to deal with an ABI directly when writing a program in a mix of programming languages, which can be achieved by using foreign function calls.

There is an entry for any virtual function declared in a class, whether it itanoum a new function or overrides a base class function, unless it overrides a function from the primary base, and conversion between their return types does not require an adjustment.

Specify location of unwind tables. This affects only type mangling, since extern “C” function objects have unmangled names.

Start at offset dsize Cincremented if necessary for alignment to xbi D for base classes or to align D for data members. All references are via the API described below. The mangled name of a guard variable is the name of the guarded variable prefixed with GV. The class also has a virtual table that is not copied from the virtual base class virtual tables.

Or, as the quotee implies, is packing wbi unspecified between toolchains but in fact reliable and predictable within the use of a certain ABI?

Its allocation is similar to case 2 above, except that additional candidate offsets are considered before starting at dsize C. Combine vtable content and order sections; clarify ordering.