[SelectionDAG] Make binop reduction matcher available to all targets

There is nothing x86-specific about this code, so it'd be nice to make this available for other targets to use in the future (and get it out of X86ISelLowering!).

Differential Revision: https://reviews.llvm.org/D50083

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@338586 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed