[cfe-dev] adding attribute bits to types

[Mattias Holm]

Hi,

I am currently working on an experiment where I am adding additional 
type qualifiers on struct instances (this is done with the __attribute__ 
syntax).

Syntactically in C, I am trying to do something like this at the moment:

typedef struct Foo {
   ...
} Foo;

#define BAR __attribute__((bar))

void f(void) {
   BAR Foo *baz = ...;
   ...
}

This attribute will then be used to influence the code generator.

I made some hacks to add these extra attributes in the attribute parser 
and then some in SemaType.cpp: ProcessTypeAttributeList in order to 
process these attributes. So far that works well.

My idea then is that I add some extra tag bits to the RecordType class 
(or to subclass it, but that's a minor issue) in order to keep track of 
these extra qualifiers, but that then means that I probably need to 
unique these as new record types and add the new (attribute) qualified 
types to the ASTContext, right? Here I am stuck at the moment, and I do 
not understand how and where a record type is looked up and added to the 
AST context. Some pointers where I should look would be nice.

Would it be a better and/or easier approach, to add the bits to the 
QualType class instead?


Regards,
Mattias