Added instruction combine to transform few more negative values addition to subtraction (Part 1)
This patch enables transforms for following patterns.
  (x + (~(y & c) + 1)   -->   x - (y & c)
  (x + (~((y >> z) & c) + 1)   -->   x - ((y>>z) & c)

Differential Revision: http://reviews.llvm.org/D3733



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211266 91177308-0d34-0410-b5e6-96231b3b80d8