Allow targets to select source order pre-RA scheduler.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148033 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index bfb6dfa..9f39699 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -218,7 +218,8 @@
                                              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);