Changes from review:

- Move DisableScheduling flag into TargetOption.h
- Move SDNodeOrdering into its own header file. Give it a minimal interface that
  doesn't conflate construction with storage.
- Move assigning the ordering into the SelectionDAGBuilder.

This isn't used yet, so there should be no functional changes.

llvm-svn: 91727

llvm/lib/Target/TargetMachine.cpp

@@ -46,6 +46,7 @@ namespace llvm {
   bool DisableJumpTables;
   bool StrongPHIElim;
   bool AsmVerbosityDefault(false);
+  bool DisableScheduling;
 }
 
 static cl::opt<bool, true>
@@ -197,6 +198,11 @@ EnableStrongPHIElim(cl::Hidden, "strong-phi-elim",
   cl::desc("Use strong PHI elimination."),
   cl::location(StrongPHIElim),
   cl::init(false));
+static cl::opt<bool, true>
+DisableInstScheduling("disable-scheduling",
+  cl::desc("Disable instruction scheduling"),
+  cl::location(DisableScheduling),
+  cl::init(false));
 
 //---------------------------------------------------------------------------
 // TargetMachine Class