Remove some register allocation order dependencies.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172874 91177308-0d34-0410-b5e6-96231b3b80d8
Fix 80-col and early exit in cost model

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172877 91177308-0d34-0410-b5e6-96231b3b80d8