MI-Sched: Track multiple candidates with the same priority level.

This eliminates the MultiPressure scheduling "reason". It was
sensitive to queue order. We don't like being sensitive to queue
order.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184129 91177308-0d34-0410-b5e6-96231b3b80d8
MI-Sched: Remove another heuristic that is sensitive to queue order.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184130 91177308-0d34-0410-b5e6-96231b3b80d8
MI Sched: fix a typo in RegPressure heuristics.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184131 91177308-0d34-0410-b5e6-96231b3b80d8
Remove compareRPDelta.

A complex, expensive heuristic with little value in the current design.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184132 91177308-0d34-0410-b5e6-96231b3b80d8
Give RegMax higher priority.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184133 91177308-0d34-0410-b5e6-96231b3b80d8
Reenable, improve, and add MI-Sched unit tests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184134 91177308-0d34-0410-b5e6-96231b3b80d8
MI-Sched: handle ReadAdvance latencies as used by Swift.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184135 91177308-0d34-0410-b5e6-96231b3b80d8
Convert two uses of eraseFromDisk.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184136 91177308-0d34-0410-b5e6-96231b3b80d8