[Clang] Convergent Attribute

[Matt Arsenault via cfe-commits]

On 05/06/2016 02:53 PM, Richard Smith via cfe-commits wrote:
> It looks like we added the noduplicate attribute to clang to support 
> OpenCL's barrier function. Did we get the semantics for it wrong for 
> its intended use case?
Yes. Noduplicate is essentially deprecated in favor of convergent. 
noduplicate is too strict, duplicating is OK in the case of unrolling a 
loop with a barrier for example.