[X86] Use ADD/SUB instead of INC/DEC for Haswell and Broadwell CPUs

Differential Revision: http://reviews.llvm.org/D5934



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222141 91177308-0d34-0410-b5e6-96231b3b80d8
[Reassociate] As the expression tree is rewritten make sure the operands are
emitted in canonical form.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222142 91177308-0d34-0410-b5e6-96231b3b80d8