[cfe-dev] Setting readnone attribute for function declaration

[Chris Lattner]

On Aug 27, 2010, at 7:17 AM, ihusar wrote:

> Hello,
> 
>   I would like to ask, if there is a way how to set  readnone attribute for a function declaration.
> (http://llvm.org/docs/LangRef.html#fnattrs)
> 
> Lets say I would like to have such function:
> 
> short __attribute__((readnone)) fun(short a, short b, int c);
> 
> However, the clang frontend (v.1.0), does print a warning, that the readnone attribute is ignored.
> I looked in the newest revision sources, but it does not seem that it is supported either.
> Do you know whether it is possible to convince the frontend, that this function should have the
> readnone attribute (I need this to allow optimizations over this function call boundary to happen)?

In C code, we follow the GCC naming of the attributes, so readnone = attribute(const) and readonly = attribute(pure).

-Chris