[PATCH] [SLPVectorization] Vectorize Reduction Chain feeding into a 'return' statement

[hfinkel at anl.gov]

> I do have one question - Should this be moved under a special 'flag' (same as horizontal store)?

I think that this is not necessary (unless we find that it introduces performance regressions); I don't see any reason for the cost modeling to be special here. Arnold, do you agree?

http://reviews.llvm.org/D6227