[LLVMdev] Patch for 3.2

[Duncan Sands]

Hi Pawel, can you please pull this into the 3.2 branch:

http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20121112/156206.html

It fixes a wrong simplification of "A+B==B+A".

Thanks, Duncan.