--- a/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp	Thu Dec 12 15:22:36 2013 +0900
+++ b/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp	Mon Sep 08 22:06:00 2014 +0900
@@ -12,7 +12,6 @@
 //
 //===----------------------------------------------------------------------===//
 
-#define DEBUG_TYPE "pre-RA-sched"
 #include "ScheduleDAGSDNodes.h"
 #include "InstrEmitter.h"
 #include "SDNodeDbgValue.h"
@@ -35,6 +34,8 @@
 #include "llvm/Target/TargetSubtargetInfo.h"
 using namespace llvm;
 
+#define DEBUG_TYPE "pre-RA-sched"
+
 STATISTIC(LoadsClustered, "Number of loads clustered together");
 
 // This allows latency based scheduler to notice high latency instructions
@@ -46,8 +47,8 @@
            "instructions take for targets with no itinerary"));
 
 ScheduleDAGSDNodes::ScheduleDAGSDNodes(MachineFunction &mf)
-  : ScheduleDAG(mf), BB(0), DAG(0),
-    InstrItins(mf.getTarget().getInstrItineraryData()) {}
+    : ScheduleDAG(mf), BB(nullptr), DAG(nullptr),
+      InstrItins(mf.getSubtarget().getInstrItineraryData()) {}
 
 /// Run - perform scheduling.
 ///
@@ -67,12 +68,12 @@
 ///
 SUnit *ScheduleDAGSDNodes::newSUnit(SDNode *N) {
 #ifndef NDEBUG
-  const SUnit *Addr = 0;
+  const SUnit *Addr = nullptr;
   if (!SUnits.empty())
     Addr = &SUnits[0];
 #endif
   SUnits.push_back(SUnit(N, (unsigned)SUnits.size()));
-  assert((Addr == 0 || Addr == &SUnits[0]) &&
+  assert((Addr == nullptr || Addr == &SUnits[0]) &&
          "SUnits std::vector reallocated on the fly!");
   SUnits.back().OrigNode = &SUnits.back();
   SUnit *SU = &SUnits.back();
@@ -135,15 +136,15 @@
 static void CloneNodeWithValues(SDNode *N, SelectionDAG *DAG,
                                 SmallVectorImpl<EVT> &VTs,
                                 SDValue ExtraOper = SDValue()) {
-  SmallVector<SDValue, 4> Ops;
+  SmallVector<SDValue, 8> Ops;
   for (unsigned I = 0, E = N->getNumOperands(); I != E; ++I)
     Ops.push_back(N->getOperand(I));
 
   if (ExtraOper.getNode())
     Ops.push_back(ExtraOper);
 
-  SDVTList VTList = DAG->getVTList(&VTs[0], VTs.size());
-  MachineSDNode::mmo_iterator Begin = 0, End = 0;
+  SDVTList VTList = DAG->getVTList(VTs);
+  MachineSDNode::mmo_iterator Begin = nullptr, End = nullptr;
   MachineSDNode *MN = dyn_cast<MachineSDNode>(N);
 
   // Store memory references.
@@ -152,7 +153,7 @@
     End = MN->memoperands_end();
   }
 
-  DAG->MorphNodeTo(N, N->getOpcode(), VTList, &Ops[0], Ops.size());
+  DAG->MorphNodeTo(N, N->getOpcode(), VTList, Ops);
 
   // Reset the memory references
   if (MN)
@@ -205,7 +206,7 @@
 /// outputs to ensure they are scheduled together and in order. This
 /// optimization may benefit some targets by improving cache locality.
 void ScheduleDAGSDNodes::ClusterNeighboringLoads(SDNode *Node) {
-  SDNode *Chain = 0;
+  SDNode *Chain = nullptr;
   unsigned NumOps = Node->getNumOperands();
   if (Node->getOperand(NumOps-1).getValueType() == MVT::Other)
     Chain = Node->getOperand(NumOps-1).getNode();
@@ -219,8 +220,11 @@
   DenseMap<long long, SDNode*> O2SMap;  // Map from offset to SDNode.
   bool Cluster = false;
   SDNode *Base = Node;
+  // This algorithm requires a reasonably low use count before finding a match
+  // to avoid uselessly blowing up compile time in large blocks.
+  unsigned UseCount = 0;
   for (SDNode::use_iterator I = Chain->use_begin(), E = Chain->use_end();
-       I != E; ++I) {
+       I != E && UseCount < 100; ++I, ++UseCount) {
     SDNode *User = *I;
     if (User == Node || !Visited.insert(User))
       continue;
@@ -237,6 +241,8 @@
     if (Offset2 < Offset1)
       Base = User;
     Cluster = true;
+    // Reset UseCount to allow more matches.
+    UseCount = 0;
   }
 
   if (!Cluster)
@@ -266,7 +272,7 @@
   // Cluster loads by adding MVT::Glue outputs and inputs. This also
   // ensure they are scheduled in order of increasing addresses.
   SDNode *Lead = Loads[0];
-  SDValue InGlue = SDValue(0, 0);
+  SDValue InGlue = SDValue(nullptr, 0);
   if (AddGlue(Lead, InGlue, true, DAG))
     InGlue = SDValue(Lead, Lead->getNumValues() - 1);
   for (unsigned I = 1, E = Loads.size(); I != E; ++I) {
@@ -567,7 +573,7 @@
       return; // Found a normal regdef.
     }
     Node = Node->getGluedNode();
-    if (Node == NULL) {
+    if (!Node) {
       return; // No values left to visit.
     }
     InitNodeNumDefs();
@@ -738,13 +744,13 @@
   if (Emitter.getInsertPos() == BB->begin() || BB->back().isPHI() ||
       // Fast-isel may have inserted some instructions, in which case the
       // BB->back().isPHI() test will not fire when we want it to.
-      prior(Emitter.getInsertPos())->isPHI()) {
+      std::prev(Emitter.getInsertPos())->isPHI()) {
     // Did not insert any instruction.
-    Orders.push_back(std::make_pair(Order, (MachineInstr*)0));
+    Orders.push_back(std::make_pair(Order, (MachineInstr*)nullptr));
     return;
   }
 
-  Orders.push_back(std::make_pair(Order, prior(Emitter.getInsertPos())));
+  Orders.push_back(std::make_pair(Order, std::prev(Emitter.getInsertPos())));
   ProcessSDDbgValues(N, DAG, Emitter, Orders, VRBaseMap, Order);
 }