This is the first stage in refactoring the pipeliner and making it more
accessible for backends to override and control. This separates the logic and
state required to *emit* a scheudule from the logic that *computes* and
validates a schedule.
This will enable (a) new schedule emitters and (b) new modulo scheduling
implementations to coexist.
NFC.
Differential Revision: https://reviews.llvm.org/D67006
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@370500 91177308-0d34-0410-b5e6-96231b3b80d8
James Molloy