Machine dependent attributes can be specified for types and/or declarations. Currently only subprogram entities are supported. This pragma is semantically equivalent to __attribute__((string_expression)) in GNU C, where string_expression> is recognized by the GNU C macros VALID_MACHINE_TYPE_ATTRIBUTE and VALID_MACHINE_DECL_ATTRIBUTE which are defined in the configuration header file tm.h for each machine. See the GCC manual for further information.