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6.4.2.3 ARC Attributes ¶

These attributes are supported by the ARC back end:

interrupt ¶

This attribute applies to functions.

It indicates that the specified function is an interrupt handler. The compiler generates function entry and exit sequences suitable for use in an interrupt handler when this attribute is present.

On the ARC, you must specify the kind of interrupt to be handled in a parameter to the interrupt attribute like this:

void f () __attribute__ ((interrupt ("ilink1")));

Permissible values for this parameter are: ilink1 and ilink2 for ARCv1 architecture, and ilink and firq for ARCv2 architecture.

long_call ¶

medium_call

short_call

These attributes apply to functions.

These attributes specify how a particular function is called. They override the -mlong-calls and -mmedium-calls (see ARC Options) command-line switches and #pragma long_calls settings.

For ARC, a function marked with the long_call attribute is always called using register-indirect jump-and-link instructions, thereby enabling the called function to be placed anywhere within the 32-bit address space. A function marked with the medium_call attribute will always be close enough to be called with an unconditional branch-and-link instruction, which has a 25-bit offset from the call site. A function marked with the short_call attribute will always be close enough to be called with a conditional branch-and-link instruction, which has a 21-bit offset from the call site.

jli_always ¶

This attribute applies to functions.

It forces the associated function to be called using a jli instruction. The jli instruction makes use of a table stored into .jlitab section, which holds the location of the functions which are addressed using this instruction.

jli_fixed ¶

This attribute applies to functions.

Identical to jli_always above, but the location of the function in the jli table is known and given as an attribute parameter.

secure_call ¶

This attribute applies to functions.

It allows you to mark secure-code functions that are callable from normal mode. The location of the secure call function into the sjli table needs to be passed as argument.

aux ¶

This attribute applies to variables.

The aux attribute is used to directly access the ARC’s auxiliary register space from C. The auxiliary register number is given via attribute argument.

uncached ¶

This attribute applies to types.

Declaring objects with the uncached type attribute allows you to exclude data-cache participation in load and store operations on those objects without involving the additional semantic implications of volatile. The .di instruction suffix is used for all loads and stores of data declared uncached.