6.4.2.11 IA-64 Attributes

These attributes are supported on IA-64 targets:

syscall_linkage

This attribute applies to functions.

It is used to modify the IA-64 calling convention by marking all input registers as live at all function exits. This makes it possible to restart a system call after an interrupt without having to save/restore the input registers. This also prevents kernel data from leaking into application code.

version_id

This attribute applies to global variables or functions.

This IA-64 HP-UX attribute renames the symbol to contain a version string, thus allowing for function level versioning. HP-UX system header files may use function level versioning for some system calls.

extern int foo () __attribute__((version_id ("20040821")));

Calls to foo are mapped to calls to foo{20040821}.

model (model-name)

This attribute applies to variables.

On IA-64, use this attribute to set the addressability of an object. At present, the only supported identifier for model-name is small, indicating addressability via “small” (22-bit) addresses (so that their addresses can be loaded with the addl instruction). Caveat: such addressing is by definition not position independent and hence this attribute must not be used for objects defined by shared libraries.