[PATCH] Support for address space casting in order to map these on the new 'addrspacecast' IR instruction

[David Tweed]

  Further testing (although still very limited because few codebases actually use address spaces) didn't throw up any problems, so I committed this on Michele's behalf in 4917036. (I think it's probably appropriate for Michele to apply for commit rights after several patches which have gone through review and been committed).

http://llvm-reviews.chandlerc.com/D2241