[PATCH] Add target independent attribute for ObjCARC

[Chris Lattner]

On May 20, 2013, at 10:46 AM, Bob Wilson <bob.wilson at apple.com> wrote:
>> This would be less of an immediate problem if the ARC passes weren't just unconditionally enabled by default in the optimizer pipeline, of course (or is that just for LTO?).
> 
> That is currently just for LTO.

This is an aspect of the IR validity which happens to be exposed by LTO, but it is a design problem in any case.

> Chris, what do you want to do here?  Some options:
> 
> 1. Use the existing "nobuiltin" attribute and teach the front-end to use it for ObjC runtime calls in non-ARC mode.
> 
> 2. Add a new "arcbuiltin" attribute (or whatever) and use that to mark calls that the ARC optimizer can modify.

Richard Smith is adding a new "builtin" attribute, you should use it.  See the "_Znwm is not a builtin" thread on llvmdev.

-Chris