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__attribute__
Target-specific attributes may be defined for functions, data and types. These are described using the following target hooks; they also need to be documented in extend.texi.
If defined, this target hook points to an array of `struct attribute_spec' (defined in tree.h) specifying the machine specific attributes for this target and some of the restrictions on the entities to which these attributes are applied and the arguments they take.
If defined, this target hook is a function which returns zero if the attributes on type1 and type2 are incompatible, one if they are compatible, and two if they are nearly compatible (which causes a warning to be generated). If this is not defined, machine-specific attributes are supposed always to be compatible.
If defined, this target hook is a function which assigns default attributes to newly defined type.
Define this target hook if the merging of type attributes needs special handling. If defined, the result is a list of the combined
TYPE_ATTRIBUTES
of type1 and type2. It is assumed thatcomptypes
has already been called and returned 1. This function may callmerge_attributes
to handle machine-independent merging.
Define this target hook if the merging of decl attributes needs special handling. If defined, the result is a list of the combined
DECL_ATTRIBUTES
of olddecl and newdecl. newdecl is a duplicate declaration of olddecl. Examples of when this is needed are when one attribute overrides another, or when an attribute is nullified by a subsequent definition. This function may callmerge_attributes
to handle machine-independent merging.If the only target-specific handling you require is `dllimport' for Microsoft Windows targets, you should define the macro
TARGET_DLLIMPORT_DECL_ATTRIBUTES
to1
. The compiler will then define a function calledmerge_dllimport_decl_attributes
which can then be defined as the expansion ofTARGET_MERGE_DECL_ATTRIBUTES
. You can also addhandle_dll_attribute
in the attribute table for your port to perform initial processing of the `dllimport' and `dllexport' attributes. This is done in i386/cygwin.h and i386/i386.c, for example.
Define this macro to a nonzero value if you want to treat
__declspec(X)
as equivalent to__attribute((X))
. By default, this behavior is enabled only for targets that defineTARGET_DLLIMPORT_DECL_ATTRIBUTES
. The current implementation of__declspec
is via a built-in macro, but you should not rely on this implementation detail.
Define this target hook if you want to be able to add attributes to a decl when it is being created. This is normally useful for back ends which wish to implement a pragma by using the attributes which correspond to the pragma's effect. The node argument is the decl which is being created. The attr_ptr argument is a pointer to the attribute list for this decl. The list itself should not be modified, since it may be shared with other decls, but attributes may be chained on the head of the list and
*
attr_ptr modified to point to the new attributes, or a copy of the list may be made if further changes are needed.
This target hook returns
true
if it is ok to inline fndecl into the current function, despite its having target-specific attributes,false
otherwise. By default, if a function has a target specific attribute attached to it, it will not be inlined.