misched: implemented a framework for top-down or bottom-up scheduling.

New flags: -misched-topdown, -misched-bottomup. They can be used with
the default scheduler or with -misched=shuffle. Without either
topdown/bottomup flag -misched=shuffle now alternates scheduling
direction.

LiveIntervals update is unimplemented with bottom-up scheduling, so
only -misched-topdown currently works.

Capped the ScheduleDAG hierarchy with a concrete ScheduleDAGMI class.
ScheduleDAGMI is aware of the top and bottom of the unscheduled zone
within the current region. Scheduling policy can be plugged into
the ScheduleDAGMI driver by implementing MachineSchedStrategy.
ConvergingScheduler is now the default scheduling algorithm.
It exercises the new driver but still does no reordering.

llvm-svn: 152700

1 files changed, 2 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/Passes.cpp b/llvm/lib/CodeGen/Passes.cpp
index ec1f2b4c3b2..6246c21566a 100644
--- a/llvm/lib/CodeGen/Passes.cpp
+++ b/llvm/lib/CodeGen/Passes.cpp
@@ -564,7 +564,8 @@ void TargetPassConfig::addOptimizedRegAlloc(FunctionPass *RegAllocPass) {
   addPass(RegisterCoalescerID);
 
   // PreRA instruction scheduling.
-  addPass(MachineSchedulerID);
+  if (addPass(MachineSchedulerID) != &NoPassID)
+    printAndVerify("After Machine Scheduling");
 
   // Add the selected register allocation pass.
   PM.add(RegAllocPass);