[cfe-dev] GSoC 2012: Static Function Blacklisting

[Anna Zaks]

Looks like the support for function annotations has been added to clang. See cfe/trunk/test/CodeGen/annotations-loc.c  in commit:
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20110905/046156.html
This annotation mechanism is very flexible (the user can specify the annotation names) and is probably a good match for the project. 
Anna.

On Mar 30, 2012, at 3:45 PM, Michael Han wrote:

> There is an attribute called "annotate" that enable you to embed string literals like:
> 
> __attribute__((annotate("read_only"))) struct foo;
> 
> You can find it along with all other attributes in llvm\tools\clang\include\clang\Basic\Attr.td
> 
> However, there is bug saying this attribute only work for variables but not functions and it is not fixed yet
> http://llvm.org/bugs/show_bug.cgi?id=2490 so you may end up of adding some "real" attributes, which is documented as http://clang.llvm.org/docs/InternalsManual.html#AddingAttributes 
> 
> Michael
> 
> -----Original Message-----
> From: Mark McCurry [mailto:mark.d.mccurry at gmail.com] 
> Sent: Friday, March 30, 2012 7:04 AM
> To: Michael Han
> Cc: cfe-dev at cs.uiuc.edu
> Subject: Re: [cfe-dev] GSoC 2012: Static Function Blacklisting
> 
>>> Can the annotations/attributes in clang be extended in this manner 
>>> (ignoring example syntax)?
>> You can add any attributes you like but to get them up stream would be hard as adding attributes is adding language extension and Clang definitely doesn't want to include arbitrary domain specific attributes. If you take a look at the attribute definition file, the attributes there are either from standard, or Clang built in, or already available in GCC (like thread safe annotations).
>> One idea of extending attribute system is to take a look at the Clang "annotate" attribute which you can embedded arbitrary literals so technically you can get your own annotation DSL inside the "annotate" attribute.
> 
> As of so far my searching has only resulted in finding the standard set of __attribute__() declarations defined in clang.
> ie
> http://clang-analyzer.llvm.org/annotations.html
> http://clang.llvm.org/docs/LanguageExtensions.html
> 
> Are these the annotations you are referring to or have I overlooked something?
> ie is there an __attribute__(annotate()) ?
> 
>> 
>>> Can attributes be assigned to functions without altering the source 
>>> (the library case)?
>> It is possible and what we did in our tool is to redeclare the library / 3rd party functions with annotated attributes, and in Clang Sema, merge the attributes into function types.
>> 
>>> Does this sound like a good/feasable summer of code project?
>> It should be very useful as there are many low-hanging fruits out there that could be reached by this.
>> A more ambitious goal would be to extend Clang by providing a framework to encode the attributes and the "rules" (e.g. a white/black call list of a function) so clang users could add their own domain specific checks without reinvent the wheel again.
> 
> I am not too sure how ambitious to be with the scope of this project, but I certainly do intend to make it an easily extended system, such that it will apply to a variety of use cases.
> 
> --Mark
> 
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