Keep track how many commutes are performed by the scheduler.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47710 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp b/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp
index da79a99..c87fb60 100644
--- a/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp
@@ -24,10 +24,13 @@
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetLowering.h"
+#include "llvm/ADT/Statistic.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/MathExtras.h"
 using namespace llvm;
 
+STATISTIC(NumCommutes,   "Number of instructions commuted");
+
 ScheduleDAG::ScheduleDAG(SelectionDAG &dag, MachineBasicBlock *bb,
                          const TargetMachine &tm)
   : DAG(dag), BB(bb), TM(tm), RegInfo(BB->getParent()->getRegInfo()) {
@@ -733,6 +736,7 @@
           delete MI;
           MI = NewMI;
         }
+        ++NumCommutes;
       }
     }