Allow targets to select source order pre-RA scheduler.

llvm-svn: 148033

llvm/include/llvm/Target/TargetLowering.h

@@ -56,6 +56,7 @@ namespace llvm {
   namespace Sched {
     enum Preference {
       None,             // No preference
+      Source,           // Follow source order.
       RegPressure,      // Scheduling for lowest register pressure.
       Hybrid,           // Scheduling for both latency and register pressure.
       ILP               // Scheduling for ILP in low register pressure mode.

llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

@@ -218,7 +218,8 @@ namespace llvm {
                                              CodeGenOpt::Level OptLevel) {
     const TargetLowering &TLI = IS->getTargetLowering();
 
-    if (OptLevel == CodeGenOpt::None)
+    if (OptLevel == CodeGenOpt::None ||
+        TLI.getSchedulingPreference() == Sched::Source)
       return createSourceListDAGScheduler(IS, OptLevel);
     if (TLI.getSchedulingPreference() == Sched::RegPressure)
       return createBURRListDAGScheduler(IS, OptLevel);