[PATCH] Improve Cost model for SLPVectorizer when we have a vector division by power of 2

[Sanjay Patel]

Hi all -
If we recognize that power of 2 integer division is always converted to one or more simple ops (shifts, adds, subs) for all architectures via DAGCombiner, then can we hoist the changes out of X86TargetTransformInfo and into the superclass TargetTransformInfo so we don't have to repeat this logic for every target?

http://reviews.llvm.org/D4971