[cfe-dev] adding custom attributes

[Naoya Maruyama]

Thank you Mattias. Yes, I'm currently only interested in adding
attributes to variables not types. I'll look into those files.

Naoya

On Fri, Aug 21, 2009 at 10:17 PM, Mattias Holm<holm at liacs.nl> wrote:
>> I'm new to clang and LLVM. I want to extend clang to handle
>> non-standard variable attributes. What would be the best approach to
>> that? Any help would be appreciated.
>
> Depending on what you want to do, for now I assume that you are trying
> to do something like:
>
> int x __attribute__((foo));
>
> And then have the foo attribute apply to the declaration.
>
> The interesting files for this are:
>
> include/Parser/AttributeList.h: Define an enum entry AT_foo
> lib/Parser/AttributeList.cpp: Add a memcmp call and return in order to
> allow the decoding of the attribute at the appropriate point; in the
> case of foo that would be under case 3.
>
> If you want your attribute to apply to the declaration, check the
> function ProcessDeclAttribute in lib/Sema/SemaDeclAttr.cpp, most of the
> handler called by that function do 2 things, they check the context of
> the attribute and the number of argument, and they insert the attribute
> in the declaration's attribute list, the declaration attributes need to
> inherit from the Attr class, you can find this in include/AST/Attr.h
> where a number of standard attribute classes are defined with the
> DEF_SIMPLE_ATTR macro, that macro will generate an attribute class that
> is good enough for simple boolean attributes.
>
> Your AST consumer can then read the attributes associated with the
> declaration in a later stage (check the clang Doxygen docs for how to do
> this).
>
> If you are trying to add the attributes to types and not the actual
> declarations, then it is a bit more tricky and you should check the
> thread that I started called "adding attribute bits to types".
>
>
> Regards,
> Mattias
>
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