mi-sched: bypass heuristic checks when regpressure tracking is disabled.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189988 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/ScheduleDAGInstrs.cpp

@@ -185,9 +185,6 @@ void ScheduleDAGInstrs::enterRegion(MachineBasicBlock *bb,
   RegionBegin = begin;
   RegionEnd = end;
   NumRegionInstrs = regioninstrs;
-  MISUnitMap.clear();
-
-  ScheduleDAG::clearDAG();
 }
 
 /// Close the current scheduling region. Don't clear any state in case the
@@ -703,6 +700,9 @@ void ScheduleDAGInstrs::buildSchedGraph(AliasAnalysis *AA,
                                                        : ST.useAA();
   AliasAnalysis *AAForDep = UseAA ? AA : 0;
 
+  MISUnitMap.clear();
+  ScheduleDAG::clearDAG();
+
   // Create an SUnit for each real instruction.
   initSUnits();