Add an ILP scheduler. This is a register pressure aware scheduler that's

appropriate for targets without detailed instruction iterineries.
The scheduler schedules for increased instruction level parallelism in
low register pressure situation; it schedules to reduce register pressure
when the register pressure becomes high.

On x86_64, this is a win for all tests in CFP2000. It also sped up 256.bzip2
by 16%.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109300 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/SchedulerRegistry.h

@@ -78,12 +78,19 @@ ScheduleDAGSDNodes *createTDRRListDAGScheduler(SelectionDAGISel *IS,
 ScheduleDAGSDNodes *createSourceListDAGScheduler(SelectionDAGISel *IS,
                                                  CodeGenOpt::Level OptLevel);
 
-/// createHybridListDAGScheduler - This creates a bottom up hybrid register
-/// usage reduction list scheduler that make use of latency information to
-/// avoid stalls for long latency instructions.
+/// createHybridListDAGScheduler - This creates a bottom up register pressure
+/// aware list scheduler that make use of latency information to avoid stalls
+/// for long latency instructions in low register pressure mode. In high
+/// register pressure mode it schedules to reduce register pressure.
 ScheduleDAGSDNodes *createHybridListDAGScheduler(SelectionDAGISel *IS,
                                                  CodeGenOpt::Level);
 
+/// createILPListDAGScheduler - This creates a bottom up register pressure
+/// aware list scheduler that tries to increase instruction level parallelism
+/// in low register pressure mode. In high register pressure mode it schedules
+/// to reduce register pressure.
+ScheduleDAGSDNodes *createILPListDAGScheduler(SelectionDAGISel *IS,
+                                              CodeGenOpt::Level);
 /// createTDListDAGScheduler - This creates a top-down list scheduler with
 /// a hazard recognizer.
 ScheduleDAGSDNodes *createTDListDAGScheduler(SelectionDAGISel *IS,

include/llvm/Target/TargetMachine.h

@@ -75,7 +75,8 @@ namespace Sched {
     None,             // No preference
     Latency,          // Scheduling for shortest total latency.
     RegPressure,      // Scheduling for lowest register pressure.
-    Hybrid            // Scheduling for both latency and register pressure.
+    Hybrid,           // Scheduling for both latency and register pressure.
+    ILP               // Scheduling for ILP in low register pressure mode.
   };
 }