Remove some old experimental code that is no longer needed. Remove additional, speculative scheduling pass as its cost did not translate into significant performance improvement. Minor tweaks.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89471 91177308-0d34-0410-b5e6-96231b3b80d8

8 files changed, 79 insertions, 241 deletions

diff --git a/lib/CodeGen/AggressiveAntiDepBreaker.cpp b/lib/CodeGen/AggressiveAntiDepBreaker.cpp
index 76451bb9a9..f9c2bf02a4 100644
--- a/lib/CodeGen/AggressiveAntiDepBreaker.cpp
+++ b/lib/CodeGen/AggressiveAntiDepBreaker.cpp
@@ -28,11 +28,6 @@
 #include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
-static cl::opt<int>
-AntiDepTrials("agg-antidep-trials",
-              cl::desc("Maximum number of anti-dependency breaking passes"),
-              cl::init(1), cl::Hidden);
-
 // If DebugDiv > 0 then only break antidep with (ID % DebugDiv) == DebugMod
 static cl::opt<int>
 DebugDiv("agg-antidep-debugdiv",
@@ -118,7 +113,7 @@ AggressiveAntiDepBreaker(MachineFunction& MFi,
   MRI(MF.getRegInfo()),
   TRI(MF.getTarget().getRegisterInfo()),
   AllocatableSet(TRI->getAllocatableSet(MF)),
-  State(NULL), SavedState(NULL) {
+  State(NULL) {
   /* Collect a bitset of all registers that are only broken if they
      are on the critical path. */
   for (unsigned i = 0, e = CriticalPathRCs.size(); i < e; ++i) {
@@ -138,13 +133,6 @@ AggressiveAntiDepBreaker(MachineFunction& MFi,
 
 AggressiveAntiDepBreaker::~AggressiveAntiDepBreaker() {
   delete State;
-  delete SavedState;
-}
-
-unsigned AggressiveAntiDepBreaker::GetMaxTrials() {
-  if (AntiDepTrials <= 0)
-    return 1;
-  return AntiDepTrials;
 }
 
 void AggressiveAntiDepBreaker::StartBlock(MachineBasicBlock *BB) {
@@ -216,8 +204,6 @@ void AggressiveAntiDepBreaker::StartBlock(MachineBasicBlock *BB) {
 void AggressiveAntiDepBreaker::FinishBlock() {
   delete State;
   State = NULL;
-  delete SavedState;
-  SavedState = NULL;
 }
 
 void AggressiveAntiDepBreaker::Observe(MachineInstr *MI, unsigned Count,
@@ -251,10 +237,6 @@ void AggressiveAntiDepBreaker::Observe(MachineInstr *MI, unsigned Count,
     }
   }
   DEBUG(errs() << '\n');
-
-  // We're starting a new schedule region so forget any saved state.
-  delete SavedState;
-  SavedState = NULL;
 }
 
 bool AggressiveAntiDepBreaker::IsImplicitDefUse(MachineInstr *MI,
@@ -293,27 +275,20 @@ void AggressiveAntiDepBreaker::GetPassthruRegs(MachineInstr *MI,
   }
 }
 
-/// AntiDepEdges - Return in Edges the anti- and output-
-/// dependencies on Regs in SU that we want to consider for breaking.
-static void AntiDepEdges(SUnit *SU, 
-                         const AntiDepBreaker::AntiDepRegVector& Regs,
-                         std::vector<SDep*>& Edges) {
-  AntiDepBreaker::AntiDepRegSet RegSet;
-  for (unsigned i = 0, e = Regs.size(); i < e; ++i)
-    RegSet.insert(Regs[i]);
-
+/// AntiDepEdges - Return in Edges the anti- and output- dependencies
+/// in SU that we want to consider for breaking.
+static void AntiDepEdges(SUnit *SU, std::vector<SDep*>& Edges) {
+  SmallSet<unsigned, 4> RegSet;
   for (SUnit::pred_iterator P = SU->Preds.begin(), PE = SU->Preds.end();
        P != PE; ++P) {
     if ((P->getKind() == SDep::Anti) || (P->getKind() == SDep::Output)) {
       unsigned Reg = P->getReg();
-      if (RegSet.count(Reg) != 0) {
+      if (RegSet.count(Reg) == 0) {
         Edges.push_back(&*P);
-        RegSet.erase(Reg);
+        RegSet.insert(Reg);
       }
     }
   }
-
-  assert(RegSet.empty() && "Expected all antidep registers to be found");
 }
 
 /// CriticalPathStep - Return the next SUnit after SU on the bottom-up
@@ -698,7 +673,6 @@ bool AggressiveAntiDepBreaker::FindSuitableFreeRegisters(
 ///
 unsigned AggressiveAntiDepBreaker::BreakAntiDependencies(
                               std::vector<SUnit>& SUnits,
-                              CandidateMap& Candidates,
                               MachineBasicBlock::iterator& Begin,
                               MachineBasicBlock::iterator& End,
                               unsigned InsertPosIndex) {
@@ -711,16 +685,6 @@ unsigned AggressiveAntiDepBreaker::BreakAntiDependencies(
   // so just duck out immediately if the block is empty.
   if (SUnits.empty()) return 0;
   
-  // Manage saved state to enable multiple passes...
-  if (AntiDepTrials > 1) {
-    if (SavedState == NULL) {
-      SavedState = new AggressiveAntiDepState(*State);
-    } else {
-      delete State;
-      State = new AggressiveAntiDepState(*SavedState);
-    }
-  }
-  
   // For each regclass the next register to use for renaming.
   RenameOrderType RenameOrder;
 
@@ -749,21 +713,14 @@ unsigned AggressiveAntiDepBreaker::BreakAntiDependencies(
     CriticalPathMI = CriticalPathSU->getInstr();
   }
 
-  // Even if there are no anti-dependencies we still need to go
-  // through the instructions to update Def, Kills, etc.
 #ifndef NDEBUG 
-  if (Candidates.empty()) {
-    DEBUG(errs() << "\n===== No anti-dependency candidates\n");
-  } else {
-    DEBUG(errs() << "\n===== Attempting to break " << Candidates.size() << 
-          " anti-dependencies\n");
-    DEBUG(errs() << "Available regs:");
-    for (unsigned Reg = 0; Reg < TRI->getNumRegs(); ++Reg) {
-      if (!State->IsLive(Reg))
-        DEBUG(errs() << " " << TRI->getName(Reg));
-    }
-    DEBUG(errs() << '\n');
+  DEBUG(errs() << "\n===== Aggressive anti-dependency breaking\n");
+  DEBUG(errs() << "Available regs:");
+  for (unsigned Reg = 0; Reg < TRI->getNumRegs(); ++Reg) {
+    if (!State->IsLive(Reg))
+      DEBUG(errs() << " " << TRI->getName(Reg));
   }
+  DEBUG(errs() << '\n');
 #endif
 
   // Attempt to break anti-dependence edges. Walk the instructions
@@ -784,14 +741,11 @@ unsigned AggressiveAntiDepBreaker::BreakAntiDependencies(
     // Process the defs in MI...
     PrescanInstruction(MI, Count, PassthruRegs);
     
-    // The the dependence edges that represent anti- and output-
+    // The dependence edges that represent anti- and output-
     // dependencies that are candidates for breaking.
     std::vector<SDep*> Edges;
     SUnit *PathSU = MISUnitMap[MI];
-    AntiDepBreaker::CandidateMap::iterator 
-      citer = Candidates.find(PathSU);
-    if (citer != Candidates.end())
-      AntiDepEdges(PathSU, citer->second, Edges);
+    AntiDepEdges(PathSU, Edges);
 
     // If MI is not on the critical path, then we don't rename
     // registers in the CriticalPathSet.
@@ -847,12 +801,32 @@ unsigned AggressiveAntiDepBreaker::BreakAntiDependencies(
           // anti-dependency since those edges would prevent such
           // units from being scheduled past each other
           // regardless.
+          //
+          // Also, if there are dependencies on other SUnits with the
+          // same register as the anti-dependency, don't attempt to
+          // break it.
           for (SUnit::pred_iterator P = PathSU->Preds.begin(),
                  PE = PathSU->Preds.end(); P != PE; ++P) {
-            if ((P->getSUnit() == NextSU) && (P->getKind() != SDep::Anti)) {
+            if (P->getSUnit() == NextSU ?
+                (P->getKind() != SDep::Anti || P->getReg() != AntiDepReg) :
+                (P->getKind() == SDep::Data && P->getReg() == AntiDepReg)) {
+              AntiDepReg = 0;
+              break;
+            }
+          }
+          for (SUnit::pred_iterator P = PathSU->Preds.begin(),
+                 PE = PathSU->Preds.end(); P != PE; ++P) {
+            if ((P->getSUnit() == NextSU) && (P->getKind() != SDep::Anti) &&
+                (P->getKind() != SDep::Output)) {
               DEBUG(errs() << " (real dependency)\n");
               AntiDepReg = 0;
               break;
+            } else if ((P->getSUnit() != NextSU) && 
+                       (P->getKind() == SDep::Data) && 
+                       (P->getReg() == AntiDepReg)) {
+              DEBUG(errs() << " (other dependency)\n");
+              AntiDepReg = 0;
+              break;
             }
           }
           
diff --git a/lib/CodeGen/AggressiveAntiDepBreaker.h b/lib/CodeGen/AggressiveAntiDepBreaker.h
index 543c102a7a..8154d2dd57 100644
--- a/lib/CodeGen/AggressiveAntiDepBreaker.h
+++ b/lib/CodeGen/AggressiveAntiDepBreaker.h
@@ -27,12 +27,11 @@
 #include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/SmallSet.h"
+#include <map>
 
 namespace llvm {
   /// Class AggressiveAntiDepState 
-  /// Contains all the state necessary for anti-dep breaking. We place
-  /// into a separate class so be can conveniently save/restore it to
-  /// enable multi-pass anti-dep breaking.
+  /// Contains all the state necessary for anti-dep breaking.
   class AggressiveAntiDepState {
   public:
     /// RegisterReference - Information about a register reference
@@ -126,23 +125,11 @@ namespace llvm {
     /// registers.
     AggressiveAntiDepState *State;
 
-    /// SavedState - The state for the start of an anti-dep
-    /// region. Used to restore the state at the beginning of each
-    /// pass
-    AggressiveAntiDepState *SavedState;
-
   public:
     AggressiveAntiDepBreaker(MachineFunction& MFi, 
                              TargetSubtarget::RegClassVector& CriticalPathRCs);
     ~AggressiveAntiDepBreaker();
     
-    /// GetMaxTrials - As anti-dependencies are broken, additional
-    /// dependencies may be exposed, so multiple passes are required.
-    unsigned GetMaxTrials();
-
-    /// NeedCandidates - Candidates required.
-    bool NeedCandidates() { return true; }
-
     /// Start - Initialize anti-dep breaking for a new basic block.
     void StartBlock(MachineBasicBlock *BB);
 
@@ -150,7 +137,6 @@ namespace llvm {
     /// of the ScheduleDAG and break them by renaming registers.
     ///
     unsigned BreakAntiDependencies(std::vector<SUnit>& SUnits,
-                                   CandidateMap& Candidates,
                                    MachineBasicBlock::iterator& Begin,
                                    MachineBasicBlock::iterator& End,
                                    unsigned InsertPosIndex);
diff --git a/lib/CodeGen/AntiDepBreaker.h b/lib/CodeGen/AntiDepBreaker.h
index b614f687a4..3ee30c6a18 100644
--- a/lib/CodeGen/AntiDepBreaker.h
+++ b/lib/CodeGen/AntiDepBreaker.h
@@ -21,9 +21,7 @@
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/ScheduleDAG.h"
 #include "llvm/Target/TargetRegisterInfo.h"
-#include "llvm/ADT/SmallSet.h"
-#include "llvm/ADT/SmallVector.h"
-#include <map>
+#include <vector>
 
 namespace llvm {
 
@@ -32,20 +30,8 @@ namespace llvm {
 /// anti-dependencies.
 class AntiDepBreaker {
 public:
-  typedef SmallSet<unsigned, 4> AntiDepRegSet;
-  typedef SmallVector<unsigned, 4> AntiDepRegVector;
-  typedef std::map<SUnit *, AntiDepRegVector> CandidateMap;
-
   virtual ~AntiDepBreaker();
 
-  /// GetMaxTrials - Return the maximum number of anti-dependence
-  /// breaking attempts that will be made for a block.
-  virtual unsigned GetMaxTrials() =0;
-
-  /// NeedCandidates - Return true if the schedule must provide
-  /// candidates with BreakAntiDependencies().
-  virtual bool NeedCandidates() =0;
-
   /// Start - Initialize anti-dep breaking for a new basic block.
   virtual void StartBlock(MachineBasicBlock *BB) =0;
 
@@ -54,7 +40,6 @@ public:
   /// the number of anti-dependencies broken.
   ///
   virtual unsigned BreakAntiDependencies(std::vector<SUnit>& SUnits,
-                                CandidateMap& Candidates,
                                 MachineBasicBlock::iterator& Begin,
                                 MachineBasicBlock::iterator& End,
                                 unsigned InsertPosIndex) =0;
diff --git a/lib/CodeGen/CriticalAntiDepBreaker.cpp b/lib/CodeGen/CriticalAntiDepBreaker.cpp
index 984e0135b8..1b39fec395 100644
--- a/lib/CodeGen/CriticalAntiDepBreaker.cpp
+++ b/lib/CodeGen/CriticalAntiDepBreaker.cpp
@@ -316,7 +316,6 @@ CriticalAntiDepBreaker::findSuitableFreeRegister(unsigned AntiDepReg,
 
 unsigned CriticalAntiDepBreaker::
 BreakAntiDependencies(std::vector<SUnit>& SUnits,
-                      CandidateMap& Candidates,
                       MachineBasicBlock::iterator& Begin,
                       MachineBasicBlock::iterator& End,
                       unsigned InsertPosIndex) {
diff --git a/lib/CodeGen/CriticalAntiDepBreaker.h b/lib/CodeGen/CriticalAntiDepBreaker.h
index 5664d852fd..496888d45f 100644
--- a/lib/CodeGen/CriticalAntiDepBreaker.h
+++ b/lib/CodeGen/CriticalAntiDepBreaker.h
@@ -25,6 +25,7 @@
 #include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/SmallSet.h"
+#include <map>
 
 namespace llvm {
   class CriticalAntiDepBreaker : public AntiDepBreaker {
@@ -64,13 +65,6 @@ namespace llvm {
     CriticalAntiDepBreaker(MachineFunction& MFi);
     ~CriticalAntiDepBreaker();
     
-    /// GetMaxTrials - Critical path anti-dependence breaking requires
-    /// only a single pass
-    unsigned GetMaxTrials() { return 1; }
-
-    /// NeedCandidates - Candidates not needed.
-    bool NeedCandidates() { return false; }
-
     /// Start - Initialize anti-dep breaking for a new basic block.
     void StartBlock(MachineBasicBlock *BB);
 
@@ -78,7 +72,6 @@ namespace llvm {
     /// of the ScheduleDAG and break them by renaming registers.
     ///
     unsigned BreakAntiDependencies(std::vector<SUnit>& SUnits,
-                                   CandidateMap& Candidates,
                                    MachineBasicBlock::iterator& Begin,
                                    MachineBasicBlock::iterator& End,
                                    unsigned InsertPosIndex);
diff --git a/lib/CodeGen/LatencyPriorityQueue.cpp b/lib/CodeGen/LatencyPriorityQueue.cpp
index 23dce4a91a..f1bd573543 100644
--- a/lib/CodeGen/LatencyPriorityQueue.cpp
+++ b/lib/CodeGen/LatencyPriorityQueue.cpp
@@ -55,10 +55,6 @@ SUnit *LatencyPriorityQueue::getSingleUnscheduledPred(SUnit *SU) {
   SUnit *OnlyAvailablePred = 0;
   for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
        I != E; ++I) {
-    if (IgnoreAntiDep && 
-        ((I->getKind() == SDep::Anti) || (I->getKind() == SDep::Output))) 
-      continue;
-
     SUnit &Pred = *I->getSUnit();
     if (!Pred.isScheduled) {
       // We found an available, but not scheduled, predecessor.  If it's the
@@ -78,10 +74,6 @@ void LatencyPriorityQueue::push_impl(SUnit *SU) {
   unsigned NumNodesBlocking = 0;
   for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
        I != E; ++I) {
-    if (IgnoreAntiDep && 
-        ((I->getKind() == SDep::Anti) || (I->getKind() == SDep::Output))) 
-      continue;
-
     if (getSingleUnscheduledPred(I->getSUnit()) == SU)
       ++NumNodesBlocking;
   }
@@ -98,10 +90,6 @@ void LatencyPriorityQueue::push_impl(SUnit *SU) {
 void LatencyPriorityQueue::ScheduledNode(SUnit *SU) {
   for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
        I != E; ++I) {
-    if (IgnoreAntiDep && 
-        ((I->getKind() == SDep::Anti) || (I->getKind() == SDep::Output))) 
-      continue;
-
     AdjustPriorityOfUnscheduledPreds(I->getSUnit());
   }
 }
diff --git a/lib/CodeGen/PostRASchedulerList.cpp b/lib/CodeGen/PostRASchedulerList.cpp
index 5f1f1f3580..9101fce27a 100644
--- a/lib/CodeGen/PostRASchedulerList.cpp
+++ b/lib/CodeGen/PostRASchedulerList.cpp
@@ -175,11 +175,10 @@ namespace {
     void FixupKills(MachineBasicBlock *MBB);
 
   private:
-    void ReleaseSucc(SUnit *SU, SDep *SuccEdge, bool IgnoreAntiDep);
-    void ReleaseSuccessors(SUnit *SU, bool IgnoreAntiDep);
-    void ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle, bool IgnoreAntiDep);
-    void ListScheduleTopDown(
-           AntiDepBreaker::CandidateMap *AntiDepCandidates);
+    void ReleaseSucc(SUnit *SU, SDep *SuccEdge);
+    void ReleaseSuccessors(SUnit *SU);
+    void ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle);
+    void ListScheduleTopDown();
     void StartBlockForKills(MachineBasicBlock *BB);
     
     // ToggleKillFlag - Toggle a register operand kill flag. Other
@@ -322,50 +321,24 @@ void SchedulePostRATDList::Schedule() {
   BuildSchedGraph(AA);
 
   if (AntiDepBreak != NULL) {
-    AntiDepBreaker::CandidateMap AntiDepCandidates;
-    const bool NeedCandidates = AntiDepBreak->NeedCandidates();
+    unsigned Broken = 
+      AntiDepBreak->BreakAntiDependencies(SUnits, Begin, InsertPos,
+                                          InsertPosIndex);
     
-    for (unsigned i = 0, Trials = AntiDepBreak->GetMaxTrials();
-         i < Trials; ++i) {
-      DEBUG(errs() << "\n********** Break Anti-Deps, Trial " << 
-            i << " **********\n");
-      
-      // If candidates are required, then schedule forward ignoring
-      // anti-dependencies to collect the candidate operands for
-      // anti-dependence breaking. The candidates will be the def
-      // operands for the anti-dependencies that if broken would allow
-      // an improved schedule
-      if (NeedCandidates) {
-        DEBUG(for (unsigned su = 0, e = SUnits.size(); su != e; ++su)
-                SUnits[su].dumpAll(this));
-
-        AntiDepCandidates.clear();
-        AvailableQueue.initNodes(SUnits);
-        ListScheduleTopDown(&AntiDepCandidates);
-        AvailableQueue.releaseState();
-      }
-
-      unsigned Broken = 
-        AntiDepBreak->BreakAntiDependencies(SUnits, AntiDepCandidates,
-                                            Begin, InsertPos, InsertPosIndex);
-
+    if (Broken != 0) {
       // We made changes. Update the dependency graph.
       // Theoretically we could update the graph in place:
       // When a live range is changed to use a different register, remove
       // the def's anti-dependence *and* output-dependence edges due to
       // that register, and add new anti-dependence and output-dependence
       // edges based on the next live range of the register.
-      if ((Broken != 0) || NeedCandidates) {
-        SUnits.clear();
-        Sequence.clear();
-        EntrySU = SUnit();
-        ExitSU = SUnit();
-        BuildSchedGraph(AA);
-      }
-
+      SUnits.clear();
+      Sequence.clear();
+      EntrySU = SUnit();
+      ExitSU = SUnit();
+      BuildSchedGraph(AA);
+      
       NumFixedAnti += Broken;
-      if (Broken == 0)
-        break;
     }
   }
 
@@ -374,7 +347,7 @@ void SchedulePostRATDList::Schedule() {
           SUnits[su].dumpAll(this));
 
   AvailableQueue.initNodes(SUnits);
-  ListScheduleTopDown(NULL);
+  ListScheduleTopDown();
   AvailableQueue.releaseState();
 }
 
@@ -573,8 +546,7 @@ void SchedulePostRATDList::FixupKills(MachineBasicBlock *MBB) {
 
 /// ReleaseSucc - Decrement the NumPredsLeft count of a successor. Add it to
 /// the PendingQueue if the count reaches zero. Also update its cycle bound.
-void SchedulePostRATDList::ReleaseSucc(SUnit *SU, SDep *SuccEdge,
-                                       bool IgnoreAntiDep) {
+void SchedulePostRATDList::ReleaseSucc(SUnit *SU, SDep *SuccEdge) {
   SUnit *SuccSU = SuccEdge->getSUnit();
 
 #ifndef NDEBUG
@@ -590,8 +562,7 @@ void SchedulePostRATDList::ReleaseSucc(SUnit *SU, SDep *SuccEdge,
   // Compute how many cycles it will be before this actually becomes
   // available.  This is the max of the start time of all predecessors plus
   // their latencies.
-  SuccSU->setDepthToAtLeast(SU->getDepth(IgnoreAntiDep) +
-                            SuccEdge->getLatency(), IgnoreAntiDep);
+  SuccSU->setDepthToAtLeast(SU->getDepth() + SuccEdge->getLatency());
   
   // If all the node's predecessors are scheduled, this node is ready
   // to be scheduled. Ignore the special ExitSU node.
@@ -600,40 +571,34 @@ void SchedulePostRATDList::ReleaseSucc(SUnit *SU, SDep *SuccEdge,
 }
 
 /// ReleaseSuccessors - Call ReleaseSucc on each of SU's successors.
-void SchedulePostRATDList::ReleaseSuccessors(SUnit *SU, bool IgnoreAntiDep) {
+void SchedulePostRATDList::ReleaseSuccessors(SUnit *SU) {
   for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
        I != E; ++I) {
-    if (IgnoreAntiDep && 
-        ((I->getKind() == SDep::Anti) || (I->getKind() == SDep::Output)))
-      continue;
-    ReleaseSucc(SU, &*I, IgnoreAntiDep);
+    ReleaseSucc(SU, &*I);
   }
 }
 
 /// ScheduleNodeTopDown - Add the node to the schedule. Decrement the pending
 /// count of its successors. If a successor pending count is zero, add it to
 /// the Available queue.
-void SchedulePostRATDList::ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle,
-                                               bool IgnoreAntiDep) {
+void SchedulePostRATDList::ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle) {
   DEBUG(errs() << "*** Scheduling [" << CurCycle << "]: ");
   DEBUG(SU->dump(this));
   
   Sequence.push_back(SU);
-  assert(CurCycle >= SU->getDepth(IgnoreAntiDep) && 
+  assert(CurCycle >= SU->getDepth() && 
          "Node scheduled above its depth!");
-  SU->setDepthToAtLeast(CurCycle, IgnoreAntiDep);
+  SU->setDepthToAtLeast(CurCycle);
 
-  ReleaseSuccessors(SU, IgnoreAntiDep);
+  ReleaseSuccessors(SU);
   SU->isScheduled = true;
   AvailableQueue.ScheduledNode(SU);
 }
 
 /// ListScheduleTopDown - The main loop of list scheduling for top-down
 /// schedulers.
-void SchedulePostRATDList::ListScheduleTopDown(
-                   AntiDepBreaker::CandidateMap *AntiDepCandidates) {
+void SchedulePostRATDList::ListScheduleTopDown() {
   unsigned CurCycle = 0;
-  const bool IgnoreAntiDep = (AntiDepCandidates != NULL);
   
   // We're scheduling top-down but we're visiting the regions in
   // bottom-up order, so we don't know the hazards at the start of a
@@ -641,33 +606,13 @@ void SchedulePostRATDList::ListScheduleTopDown(
   // blocks are a single region).
   HazardRec->Reset();
 
-  // If ignoring anti-dependencies, the Schedule DAG still has Anti
-  // dep edges, but we ignore them for scheduling purposes
-  AvailableQueue.setIgnoreAntiDep(IgnoreAntiDep);
-
   // Release any successors of the special Entry node.
-  ReleaseSuccessors(&EntrySU, IgnoreAntiDep);
+  ReleaseSuccessors(&EntrySU);
 
-  // Add all leaves to Available queue. If ignoring antideps we also
-  // adjust the predecessor count for each node to not include antidep
-  // edges.
+  // Add all leaves to Available queue.
   for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
     // It is available if it has no predecessors.
     bool available = SUnits[i].Preds.empty();
-    // If we are ignoring anti-dependencies then a node that has only
-    // anti-dep predecessors is available.
-    if (!available && IgnoreAntiDep) {
-      available = true;
-      for (SUnit::const_pred_iterator I = SUnits[i].Preds.begin(),
-             E = SUnits[i].Preds.end(); I != E; ++I) {
-        if ((I->getKind() != SDep::Anti) && (I->getKind() != SDep::Output))  {
-          available = false;
-        } else {
-          SUnits[i].NumPredsLeft -= 1;
-        }
-      }
-    }
-
     if (available) {
       AvailableQueue.push(&SUnits[i]);
       SUnits[i].isAvailable = true;
@@ -687,21 +632,21 @@ void SchedulePostRATDList::ListScheduleTopDown(
     // so, add them to the available queue.
     unsigned MinDepth = ~0u;
     for (unsigned i = 0, e = PendingQueue.size(); i != e; ++i) {
-      if (PendingQueue[i]->getDepth(IgnoreAntiDep) <= CurCycle) {
+      if (PendingQueue[i]->getDepth() <= CurCycle) {
         AvailableQueue.push(PendingQueue[i]);
         PendingQueue[i]->isAvailable = true;
         PendingQueue[i] = PendingQueue.back();
         PendingQueue.pop_back();
         --i; --e;
-      } else if (PendingQueue[i]->getDepth(IgnoreAntiDep) < MinDepth)
-        MinDepth = PendingQueue[i]->getDepth(IgnoreAntiDep);
+      } else if (PendingQueue[i]->getDepth() < MinDepth)
+        MinDepth = PendingQueue[i]->getDepth();
     }
 
     DEBUG(errs() << "\n*** Examining Available\n";
           LatencyPriorityQueue q = AvailableQueue;
           while (!q.empty()) {
             SUnit *su = q.pop();
-            errs() << "Height " << su->getHeight(IgnoreAntiDep) << ": ";
+            errs() << "Height " << su->getHeight() << ": ";
             su->dump(this);
           });
 
@@ -731,30 +676,8 @@ void SchedulePostRATDList::ListScheduleTopDown(
 
     // If we found a node to schedule...
     if (FoundSUnit) {
-      // If we are ignoring anti-dependencies and the SUnit we are
-      // scheduling has an antidep predecessor that has not been
-      // scheduled, then we will need to break that antidep if we want
-      // to get this schedule when not ignoring anti-dependencies.
-      if (IgnoreAntiDep) {
-        AntiDepBreaker::AntiDepRegVector AntiDepRegs;
-        for (SUnit::const_pred_iterator I = FoundSUnit->Preds.begin(),
-               E = FoundSUnit->Preds.end(); I != E; ++I) {
-          if (((I->getKind() == SDep::Anti) || 
-               (I->getKind() == SDep::Output)) &&
-              !I->getSUnit()->isScheduled)
-            AntiDepRegs.push_back(I->getReg());
-        }
-        
-        if (AntiDepRegs.size() > 0) {
-          DEBUG(errs() << "*** AntiDep Candidate: ");
-          DEBUG(FoundSUnit->dump(this));
-          AntiDepCandidates->insert(
-            AntiDepBreaker::CandidateMap::value_type(FoundSUnit, AntiDepRegs));
-        }
-      }
-
       // ... schedule the node...
-      ScheduleNodeTopDown(FoundSUnit, CurCycle, IgnoreAntiDep);
+      ScheduleNodeTopDown(FoundSUnit, CurCycle);
       HazardRec->EmitInstruction(FoundSUnit);
       CycleHasInsts = true;
 
@@ -775,8 +698,7 @@ void SchedulePostRATDList::ListScheduleTopDown(
         // just advance the current cycle and try again.
         DEBUG(errs() << "*** Stall in cycle " << CurCycle << '\n');
         HazardRec->AdvanceCycle();
-        if (!IgnoreAntiDep)
-          ++NumStalls;
+        ++NumStalls;
       } else {
         // Otherwise, we have no instructions to issue and we have instructions
         // that will fault if we don't do this right.  This is the case for
@@ -784,8 +706,7 @@ void SchedulePostRATDList::ListScheduleTopDown(
         DEBUG(errs() << "*** Emitting noop in cycle " << CurCycle << '\n');
         HazardRec->EmitNoop();
         Sequence.push_back(0);   // NULL here means noop
-        if (!IgnoreAntiDep)
-          ++NumNoops;
+        ++NumNoops;
       }
 
       ++CurCycle;
diff --git a/lib/CodeGen/ScheduleDAG.cpp b/lib/CodeGen/ScheduleDAG.cpp
index 6b27db263b..71693d21c6 100644
--- a/lib/CodeGen/ScheduleDAG.cpp
+++ b/lib/CodeGen/ScheduleDAG.cpp
@@ -183,8 +183,8 @@ void SUnit::setHeightDirty() {
 /// setDepthToAtLeast - Update this node's successors to reflect the
 /// fact that this node's depth just increased.
 ///
-void SUnit::setDepthToAtLeast(unsigned NewDepth, bool IgnoreAntiDep) {
-  if (NewDepth <= getDepth(IgnoreAntiDep))
+void SUnit::setDepthToAtLeast(unsigned NewDepth) {
+  if (NewDepth <= getDepth())
     return;
   setDepthDirty();
   Depth = NewDepth;
@@ -194,8 +194,8 @@ void SUnit::setDepthToAtLeast(unsigned NewDepth, bool IgnoreAntiDep) {
 /// setHeightToAtLeast - Update this node's predecessors to reflect the
 /// fact that this node's height just increased.
 ///
-void SUnit::setHeightToAtLeast(unsigned NewHeight, bool IgnoreAntiDep) {
-  if (NewHeight <= getHeight(IgnoreAntiDep))
+void SUnit::setHeightToAtLeast(unsigned NewHeight) {
+  if (NewHeight <= getHeight())
     return;
   setHeightDirty();
   Height = NewHeight;
@@ -204,7 +204,7 @@ void SUnit::setHeightToAtLeast(unsigned NewHeight, bool IgnoreAntiDep) {
 
 /// ComputeDepth - Calculate the maximal path from the node to the exit.
 ///
-void SUnit::ComputeDepth(bool IgnoreAntiDep) {
+void SUnit::ComputeDepth() {
   SmallVector<SUnit*, 8> WorkList;
   WorkList.push_back(this);
   do {
@@ -214,10 +214,6 @@ void SUnit::ComputeDepth(bool IgnoreAntiDep) {
     unsigned MaxPredDepth = 0;
     for (SUnit::const_pred_iterator I = Cur->Preds.begin(),
          E = Cur->Preds.end(); I != E; ++I) {
-      if (IgnoreAntiDep && 
-          ((I->getKind() == SDep::Anti) || (I->getKind() == SDep::Output))) 
-        continue;
-
       SUnit *PredSU = I->getSUnit();
       if (PredSU->isDepthCurrent)
         MaxPredDepth = std::max(MaxPredDepth,
@@ -241,7 +237,7 @@ void SUnit::ComputeDepth(bool IgnoreAntiDep) {
 
 /// ComputeHeight - Calculate the maximal path from the node to the entry.
 ///
-void SUnit::ComputeHeight(bool IgnoreAntiDep) {
+void SUnit::ComputeHeight() {
   SmallVector<SUnit*, 8> WorkList;
   WorkList.push_back(this);
   do {
@@ -251,10 +247,6 @@ void SUnit::ComputeHeight(bool IgnoreAntiDep) {
     unsigned MaxSuccHeight = 0;
     for (SUnit::const_succ_iterator I = Cur->Succs.begin(),
          E = Cur->Succs.end(); I != E; ++I) {
-      if (IgnoreAntiDep && 
-          ((I->getKind() == SDep::Anti) || (I->getKind() == SDep::Output))) 
-        continue;
-
       SUnit *SuccSU = I->getSUnit();
       if (SuccSU->isHeightCurrent)
         MaxSuccHeight = std::max(MaxSuccHeight,