MIsched: add an ILP window property to machine model.

This was an experimental option, but needs to be defined
per-target. e.g. PPC A2 needs to aggressively hide latency.

I converted some in-order scheduling tests to A2. Hal is working on
more test cases.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171946 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/TargetSchedule.h

@@ -84,6 +84,9 @@ public:
   /// \brief Maximum number of micro-ops that may be scheduled per cycle.
   unsigned getIssueWidth() const { return SchedModel.IssueWidth; }
 
+  /// \brief Number of cycles the OOO processor is expected to hide.
+  unsigned getILPWindow() const { return SchedModel.ILPWindow; }
+
   /// \brief Return the number of issue slots required for this MI.
   unsigned getNumMicroOps(const MachineInstr *MI,
                           const MCSchedClassDesc *SC = 0) const;