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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For purposes of substitution see Compression belowdelimited and undelimited function types are considered the same. The guard variables name is mangled based on the mangling of the guarded object name.

Name mangling – Wikipedia

Virtual base class offsets reflect the positions of the virtual base classes in the full D object. Precisely which components are present in various possible virtual tables is specified in the next section. If virtual base A has a primary base class P sharing its virtual table, P’s vcall offsets come first, in the same order they would appear if P itself were the virtual base.

Throughout this section, we assume that A is the class for which we are creating a virtual table, B is the most derived class in the hierarchy, and C is the class that contains C:: Most implementations have handled this by calling the C library atexit routine to register the destructors. Therefore function types always encode at least one parameter type, and function manglings can always be distinguished from data manglings by the presence of the type.


Name mangling

Construction virtual tables are used in a similar way during the execution of proper base class destructors. But I’ve always believed that padding and alignment were unspecified and unreliable. After these two offsets comes the encoding of the target function. Only virtual base classes but those may have non-virtual itaniu. Binary code compatibility Foreign function interface Language binding Linker dynamic Loader Year problem.

This article needs additional citations for verification. If the destructor throws a second exception, call terminate.

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

Tokens in square brackets “[]” are optional. This difference may in some rare cases lead to unresolved externals when porting such code to 64 bits.

The only exception is that a primary non-virtual base class does not require a secondary virtual pointer. When a complete object constructor is constructing a virtual base, it must be wary of using the vbase offsets in the virtual table, since the possibly shared virtual pointer may point to a construction virtual table of an unrelated base class.

Itanium C++ ABI

itanijm If the parameter declaration clause of the innermost function prototype scope has been completely seen, it is not counted in that case — which is perhaps the most common — L can be zero.


The secondary virtual table for a base class B has the same contents as the primary virtual table for B, except that: E” construct is used to describe a qualified name.

When it is for a direct or indirect pointer to a member of an incomplete class type, the incomplete class type flag is set.

Secondary virtual pointers may be required for base classes that do not require secondary VTTs.

There are two principal reasons for this: There are two cases depending on sizeof T and n: The virtual table may therefore contain components at either positive or negative offsets from its address point. Retrieved from ” https: A somewhat out-of-date version is available from the SCO website, http: All of these examples: Ooh, that is interesting.

Revise inheritance graph order definition. Resolve allocation of a virtual base class that is a primary base for another base A These include, for the bit Itanium ABI: Or, as the quotee implies, is packing merely unspecified between toolchains but in fact reliable and predictable within the use of a certain ABI? Specifically, for each type, we specify the following information about an object O of that type: The representation of this structure is implementation defined.