Provide a target override for the cost of using a callee-saved register
for the first time.

Thanks Andy for the discussion.
rdar://16162005


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204979 91177308-0d34-0410-b5e6-96231b3b80d8
[PowerPC] Use a small cleanup pass to remove VSX self copies

As explained in r204976, because of how the allocation of VSX registers
interacts with the call-lowering code, we sometimes end up generating self VSX
copies. Specifically, things like this:
  %VSL2<def> = COPY %F2, %VSL2<imp-use,kill>
(where %F2 is really a sub-register of %VSL2, and so this copy is a nop)

This adds a small cleanup pass to remove these prior to post-RA scheduling.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204980 91177308-0d34-0410-b5e6-96231b3b80d8
C++11: convert verbose loops to range-based loops.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204981 91177308-0d34-0410-b5e6-96231b3b80d8
PBQP: Minor cleanups to r204857

* Use assignment instead of swap (since the original value is being
  destroyed anyway)

* Rename "updateAdjEdgeId" to "setAdjEdgeId"

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204983 91177308-0d34-0410-b5e6-96231b3b80d8