| //===---- ScheduleDAG.cpp - Implement the ScheduleDAG class ---------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This implements the ScheduleDAG class, which is a base class used by |
| // scheduling implementation classes. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #define DEBUG_TYPE "pre-RA-sched" |
| #include "llvm/CodeGen/ScheduleDAG.h" |
| #include "llvm/CodeGen/ScheduleHazardRecognizer.h" |
| #include "llvm/CodeGen/SelectionDAGNodes.h" |
| #include "llvm/Target/TargetMachine.h" |
| #include "llvm/Target/TargetInstrInfo.h" |
| #include "llvm/Target/TargetRegisterInfo.h" |
| #include "llvm/Support/CommandLine.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include <climits> |
| using namespace llvm; |
| |
| #ifndef NDEBUG |
| static cl::opt<bool> StressSchedOpt( |
| "stress-sched", cl::Hidden, cl::init(false), |
| cl::desc("Stress test instruction scheduling")); |
| #endif |
| |
| void SchedulingPriorityQueue::anchor() { } |
| |
| ScheduleDAG::ScheduleDAG(MachineFunction &mf) |
| : TM(mf.getTarget()), |
| TII(TM.getInstrInfo()), |
| TRI(TM.getRegisterInfo()), |
| MF(mf), MRI(mf.getRegInfo()), |
| EntrySU(), ExitSU() { |
| #ifndef NDEBUG |
| StressSched = StressSchedOpt; |
| #endif |
| } |
| |
| ScheduleDAG::~ScheduleDAG() {} |
| |
| /// getInstrDesc helper to handle SDNodes. |
| const MCInstrDesc *ScheduleDAG::getNodeDesc(const SDNode *Node) const { |
| if (!Node || !Node->isMachineOpcode()) return NULL; |
| return &TII->get(Node->getMachineOpcode()); |
| } |
| |
| /// dump - dump the schedule. |
| void ScheduleDAG::dumpSchedule() const { |
| for (unsigned i = 0, e = Sequence.size(); i != e; i++) { |
| if (SUnit *SU = Sequence[i]) |
| SU->dump(this); |
| else |
| dbgs() << "**** NOOP ****\n"; |
| } |
| } |
| |
| |
| /// Run - perform scheduling. |
| /// |
| void ScheduleDAG::Run(MachineBasicBlock *bb, |
| MachineBasicBlock::iterator insertPos) { |
| BB = bb; |
| InsertPos = insertPos; |
| |
| SUnits.clear(); |
| Sequence.clear(); |
| EntrySU = SUnit(); |
| ExitSU = SUnit(); |
| |
| Schedule(); |
| |
| DEBUG({ |
| dbgs() << "*** Final schedule ***\n"; |
| dumpSchedule(); |
| dbgs() << '\n'; |
| }); |
| } |
| |
| /// addPred - This adds the specified edge as a pred of the current node if |
| /// not already. It also adds the current node as a successor of the |
| /// specified node. |
| bool SUnit::addPred(const SDep &D) { |
| // If this node already has this depenence, don't add a redundant one. |
| for (SmallVector<SDep, 4>::const_iterator I = Preds.begin(), E = Preds.end(); |
| I != E; ++I) |
| if (*I == D) |
| return false; |
| // Now add a corresponding succ to N. |
| SDep P = D; |
| P.setSUnit(this); |
| SUnit *N = D.getSUnit(); |
| // Update the bookkeeping. |
| if (D.getKind() == SDep::Data) { |
| assert(NumPreds < UINT_MAX && "NumPreds will overflow!"); |
| assert(N->NumSuccs < UINT_MAX && "NumSuccs will overflow!"); |
| ++NumPreds; |
| ++N->NumSuccs; |
| } |
| if (!N->isScheduled) { |
| assert(NumPredsLeft < UINT_MAX && "NumPredsLeft will overflow!"); |
| ++NumPredsLeft; |
| } |
| if (!isScheduled) { |
| assert(N->NumSuccsLeft < UINT_MAX && "NumSuccsLeft will overflow!"); |
| ++N->NumSuccsLeft; |
| } |
| Preds.push_back(D); |
| N->Succs.push_back(P); |
| if (P.getLatency() != 0) { |
| this->setDepthDirty(); |
| N->setHeightDirty(); |
| } |
| return true; |
| } |
| |
| /// removePred - This removes the specified edge as a pred of the current |
| /// node if it exists. It also removes the current node as a successor of |
| /// the specified node. |
| void SUnit::removePred(const SDep &D) { |
| // Find the matching predecessor. |
| for (SmallVector<SDep, 4>::iterator I = Preds.begin(), E = Preds.end(); |
| I != E; ++I) |
| if (*I == D) { |
| bool FoundSucc = false; |
| // Find the corresponding successor in N. |
| SDep P = D; |
| P.setSUnit(this); |
| SUnit *N = D.getSUnit(); |
| for (SmallVector<SDep, 4>::iterator II = N->Succs.begin(), |
| EE = N->Succs.end(); II != EE; ++II) |
| if (*II == P) { |
| FoundSucc = true; |
| N->Succs.erase(II); |
| break; |
| } |
| assert(FoundSucc && "Mismatching preds / succs lists!"); |
| (void)FoundSucc; |
| Preds.erase(I); |
| // Update the bookkeeping. |
| if (P.getKind() == SDep::Data) { |
| assert(NumPreds > 0 && "NumPreds will underflow!"); |
| assert(N->NumSuccs > 0 && "NumSuccs will underflow!"); |
| --NumPreds; |
| --N->NumSuccs; |
| } |
| if (!N->isScheduled) { |
| assert(NumPredsLeft > 0 && "NumPredsLeft will underflow!"); |
| --NumPredsLeft; |
| } |
| if (!isScheduled) { |
| assert(N->NumSuccsLeft > 0 && "NumSuccsLeft will underflow!"); |
| --N->NumSuccsLeft; |
| } |
| if (P.getLatency() != 0) { |
| this->setDepthDirty(); |
| N->setHeightDirty(); |
| } |
| return; |
| } |
| } |
| |
| void SUnit::setDepthDirty() { |
| if (!isDepthCurrent) return; |
| SmallVector<SUnit*, 8> WorkList; |
| WorkList.push_back(this); |
| do { |
| SUnit *SU = WorkList.pop_back_val(); |
| SU->isDepthCurrent = false; |
| for (SUnit::const_succ_iterator I = SU->Succs.begin(), |
| E = SU->Succs.end(); I != E; ++I) { |
| SUnit *SuccSU = I->getSUnit(); |
| if (SuccSU->isDepthCurrent) |
| WorkList.push_back(SuccSU); |
| } |
| } while (!WorkList.empty()); |
| } |
| |
| void SUnit::setHeightDirty() { |
| if (!isHeightCurrent) return; |
| SmallVector<SUnit*, 8> WorkList; |
| WorkList.push_back(this); |
| do { |
| SUnit *SU = WorkList.pop_back_val(); |
| SU->isHeightCurrent = false; |
| for (SUnit::const_pred_iterator I = SU->Preds.begin(), |
| E = SU->Preds.end(); I != E; ++I) { |
| SUnit *PredSU = I->getSUnit(); |
| if (PredSU->isHeightCurrent) |
| WorkList.push_back(PredSU); |
| } |
| } while (!WorkList.empty()); |
| } |
| |
| /// setDepthToAtLeast - Update this node's successors to reflect the |
| /// fact that this node's depth just increased. |
| /// |
| void SUnit::setDepthToAtLeast(unsigned NewDepth) { |
| if (NewDepth <= getDepth()) |
| return; |
| setDepthDirty(); |
| Depth = NewDepth; |
| isDepthCurrent = true; |
| } |
| |
| /// setHeightToAtLeast - Update this node's predecessors to reflect the |
| /// fact that this node's height just increased. |
| /// |
| void SUnit::setHeightToAtLeast(unsigned NewHeight) { |
| if (NewHeight <= getHeight()) |
| return; |
| setHeightDirty(); |
| Height = NewHeight; |
| isHeightCurrent = true; |
| } |
| |
| /// ComputeDepth - Calculate the maximal path from the node to the exit. |
| /// |
| void SUnit::ComputeDepth() { |
| SmallVector<SUnit*, 8> WorkList; |
| WorkList.push_back(this); |
| do { |
| SUnit *Cur = WorkList.back(); |
| |
| bool Done = true; |
| unsigned MaxPredDepth = 0; |
| for (SUnit::const_pred_iterator I = Cur->Preds.begin(), |
| E = Cur->Preds.end(); I != E; ++I) { |
| SUnit *PredSU = I->getSUnit(); |
| if (PredSU->isDepthCurrent) |
| MaxPredDepth = std::max(MaxPredDepth, |
| PredSU->Depth + I->getLatency()); |
| else { |
| Done = false; |
| WorkList.push_back(PredSU); |
| } |
| } |
| |
| if (Done) { |
| WorkList.pop_back(); |
| if (MaxPredDepth != Cur->Depth) { |
| Cur->setDepthDirty(); |
| Cur->Depth = MaxPredDepth; |
| } |
| Cur->isDepthCurrent = true; |
| } |
| } while (!WorkList.empty()); |
| } |
| |
| /// ComputeHeight - Calculate the maximal path from the node to the entry. |
| /// |
| void SUnit::ComputeHeight() { |
| SmallVector<SUnit*, 8> WorkList; |
| WorkList.push_back(this); |
| do { |
| SUnit *Cur = WorkList.back(); |
| |
| bool Done = true; |
| unsigned MaxSuccHeight = 0; |
| for (SUnit::const_succ_iterator I = Cur->Succs.begin(), |
| E = Cur->Succs.end(); I != E; ++I) { |
| SUnit *SuccSU = I->getSUnit(); |
| if (SuccSU->isHeightCurrent) |
| MaxSuccHeight = std::max(MaxSuccHeight, |
| SuccSU->Height + I->getLatency()); |
| else { |
| Done = false; |
| WorkList.push_back(SuccSU); |
| } |
| } |
| |
| if (Done) { |
| WorkList.pop_back(); |
| if (MaxSuccHeight != Cur->Height) { |
| Cur->setHeightDirty(); |
| Cur->Height = MaxSuccHeight; |
| } |
| Cur->isHeightCurrent = true; |
| } |
| } while (!WorkList.empty()); |
| } |
| |
| /// SUnit - Scheduling unit. It's an wrapper around either a single SDNode or |
| /// a group of nodes flagged together. |
| void SUnit::dump(const ScheduleDAG *G) const { |
| dbgs() << "SU(" << NodeNum << "): "; |
| G->dumpNode(this); |
| } |
| |
| void SUnit::dumpAll(const ScheduleDAG *G) const { |
| dump(G); |
| |
| dbgs() << " # preds left : " << NumPredsLeft << "\n"; |
| dbgs() << " # succs left : " << NumSuccsLeft << "\n"; |
| dbgs() << " # rdefs left : " << NumRegDefsLeft << "\n"; |
| dbgs() << " Latency : " << Latency << "\n"; |
| dbgs() << " Depth : " << Depth << "\n"; |
| dbgs() << " Height : " << Height << "\n"; |
| |
| if (Preds.size() != 0) { |
| dbgs() << " Predecessors:\n"; |
| for (SUnit::const_succ_iterator I = Preds.begin(), E = Preds.end(); |
| I != E; ++I) { |
| dbgs() << " "; |
| switch (I->getKind()) { |
| case SDep::Data: dbgs() << "val "; break; |
| case SDep::Anti: dbgs() << "anti"; break; |
| case SDep::Output: dbgs() << "out "; break; |
| case SDep::Order: dbgs() << "ch "; break; |
| } |
| dbgs() << "#"; |
| dbgs() << I->getSUnit() << " - SU(" << I->getSUnit()->NodeNum << ")"; |
| if (I->isArtificial()) |
| dbgs() << " *"; |
| dbgs() << ": Latency=" << I->getLatency(); |
| if (I->isAssignedRegDep()) |
| dbgs() << " Reg=" << G->TRI->getName(I->getReg()); |
| dbgs() << "\n"; |
| } |
| } |
| if (Succs.size() != 0) { |
| dbgs() << " Successors:\n"; |
| for (SUnit::const_succ_iterator I = Succs.begin(), E = Succs.end(); |
| I != E; ++I) { |
| dbgs() << " "; |
| switch (I->getKind()) { |
| case SDep::Data: dbgs() << "val "; break; |
| case SDep::Anti: dbgs() << "anti"; break; |
| case SDep::Output: dbgs() << "out "; break; |
| case SDep::Order: dbgs() << "ch "; break; |
| } |
| dbgs() << "#"; |
| dbgs() << I->getSUnit() << " - SU(" << I->getSUnit()->NodeNum << ")"; |
| if (I->isArtificial()) |
| dbgs() << " *"; |
| dbgs() << ": Latency=" << I->getLatency(); |
| dbgs() << "\n"; |
| } |
| } |
| dbgs() << "\n"; |
| } |
| |
| #ifndef NDEBUG |
| /// VerifySchedule - Verify that all SUnits were scheduled and that |
| /// their state is consistent. |
| /// |
| void ScheduleDAG::VerifySchedule(bool isBottomUp) { |
| bool AnyNotSched = false; |
| unsigned DeadNodes = 0; |
| unsigned Noops = 0; |
| for (unsigned i = 0, e = SUnits.size(); i != e; ++i) { |
| if (!SUnits[i].isScheduled) { |
| if (SUnits[i].NumPreds == 0 && SUnits[i].NumSuccs == 0) { |
| ++DeadNodes; |
| continue; |
| } |
| if (!AnyNotSched) |
| dbgs() << "*** Scheduling failed! ***\n"; |
| SUnits[i].dump(this); |
| dbgs() << "has not been scheduled!\n"; |
| AnyNotSched = true; |
| } |
| if (SUnits[i].isScheduled && |
| (isBottomUp ? SUnits[i].getHeight() : SUnits[i].getDepth()) > |
| unsigned(INT_MAX)) { |
| if (!AnyNotSched) |
| dbgs() << "*** Scheduling failed! ***\n"; |
| SUnits[i].dump(this); |
| dbgs() << "has an unexpected " |
| << (isBottomUp ? "Height" : "Depth") << " value!\n"; |
| AnyNotSched = true; |
| } |
| if (isBottomUp) { |
| if (SUnits[i].NumSuccsLeft != 0) { |
| if (!AnyNotSched) |
| dbgs() << "*** Scheduling failed! ***\n"; |
| SUnits[i].dump(this); |
| dbgs() << "has successors left!\n"; |
| AnyNotSched = true; |
| } |
| } else { |
| if (SUnits[i].NumPredsLeft != 0) { |
| if (!AnyNotSched) |
| dbgs() << "*** Scheduling failed! ***\n"; |
| SUnits[i].dump(this); |
| dbgs() << "has predecessors left!\n"; |
| AnyNotSched = true; |
| } |
| } |
| } |
| for (unsigned i = 0, e = Sequence.size(); i != e; ++i) |
| if (!Sequence[i]) |
| ++Noops; |
| assert(!AnyNotSched); |
| assert(Sequence.size() + DeadNodes - Noops == SUnits.size() && |
| "The number of nodes scheduled doesn't match the expected number!"); |
| } |
| #endif |
| |
| /// InitDAGTopologicalSorting - create the initial topological |
| /// ordering from the DAG to be scheduled. |
| /// |
| /// The idea of the algorithm is taken from |
| /// "Online algorithms for managing the topological order of |
| /// a directed acyclic graph" by David J. Pearce and Paul H.J. Kelly |
| /// This is the MNR algorithm, which was first introduced by |
| /// A. Marchetti-Spaccamela, U. Nanni and H. Rohnert in |
| /// "Maintaining a topological order under edge insertions". |
| /// |
| /// Short description of the algorithm: |
| /// |
| /// Topological ordering, ord, of a DAG maps each node to a topological |
| /// index so that for all edges X->Y it is the case that ord(X) < ord(Y). |
| /// |
| /// This means that if there is a path from the node X to the node Z, |
| /// then ord(X) < ord(Z). |
| /// |
| /// This property can be used to check for reachability of nodes: |
| /// if Z is reachable from X, then an insertion of the edge Z->X would |
| /// create a cycle. |
| /// |
| /// The algorithm first computes a topological ordering for the DAG by |
| /// initializing the Index2Node and Node2Index arrays and then tries to keep |
| /// the ordering up-to-date after edge insertions by reordering the DAG. |
| /// |
| /// On insertion of the edge X->Y, the algorithm first marks by calling DFS |
| /// the nodes reachable from Y, and then shifts them using Shift to lie |
| /// immediately after X in Index2Node. |
| void ScheduleDAGTopologicalSort::InitDAGTopologicalSorting() { |
| unsigned DAGSize = SUnits.size(); |
| std::vector<SUnit*> WorkList; |
| WorkList.reserve(DAGSize); |
| |
| Index2Node.resize(DAGSize); |
| Node2Index.resize(DAGSize); |
| |
| // Initialize the data structures. |
| for (unsigned i = 0, e = DAGSize; i != e; ++i) { |
| SUnit *SU = &SUnits[i]; |
| int NodeNum = SU->NodeNum; |
| unsigned Degree = SU->Succs.size(); |
| // Temporarily use the Node2Index array as scratch space for degree counts. |
| Node2Index[NodeNum] = Degree; |
| |
| // Is it a node without dependencies? |
| if (Degree == 0) { |
| assert(SU->Succs.empty() && "SUnit should have no successors"); |
| // Collect leaf nodes. |
| WorkList.push_back(SU); |
| } |
| } |
| |
| int Id = DAGSize; |
| while (!WorkList.empty()) { |
| SUnit *SU = WorkList.back(); |
| WorkList.pop_back(); |
| Allocate(SU->NodeNum, --Id); |
| for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end(); |
| I != E; ++I) { |
| SUnit *SU = I->getSUnit(); |
| if (!--Node2Index[SU->NodeNum]) |
| // If all dependencies of the node are processed already, |
| // then the node can be computed now. |
| WorkList.push_back(SU); |
| } |
| } |
| |
| Visited.resize(DAGSize); |
| |
| #ifndef NDEBUG |
| // Check correctness of the ordering |
| for (unsigned i = 0, e = DAGSize; i != e; ++i) { |
| SUnit *SU = &SUnits[i]; |
| for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end(); |
| I != E; ++I) { |
| assert(Node2Index[SU->NodeNum] > Node2Index[I->getSUnit()->NodeNum] && |
| "Wrong topological sorting"); |
| } |
| } |
| #endif |
| } |
| |
| /// AddPred - Updates the topological ordering to accommodate an edge |
| /// to be added from SUnit X to SUnit Y. |
| void ScheduleDAGTopologicalSort::AddPred(SUnit *Y, SUnit *X) { |
| int UpperBound, LowerBound; |
| LowerBound = Node2Index[Y->NodeNum]; |
| UpperBound = Node2Index[X->NodeNum]; |
| bool HasLoop = false; |
| // Is Ord(X) < Ord(Y) ? |
| if (LowerBound < UpperBound) { |
| // Update the topological order. |
| Visited.reset(); |
| DFS(Y, UpperBound, HasLoop); |
| assert(!HasLoop && "Inserted edge creates a loop!"); |
| // Recompute topological indexes. |
| Shift(Visited, LowerBound, UpperBound); |
| } |
| } |
| |
| /// RemovePred - Updates the topological ordering to accommodate an |
| /// an edge to be removed from the specified node N from the predecessors |
| /// of the current node M. |
| void ScheduleDAGTopologicalSort::RemovePred(SUnit *M, SUnit *N) { |
| // InitDAGTopologicalSorting(); |
| } |
| |
| /// DFS - Make a DFS traversal to mark all nodes reachable from SU and mark |
| /// all nodes affected by the edge insertion. These nodes will later get new |
| /// topological indexes by means of the Shift method. |
| void ScheduleDAGTopologicalSort::DFS(const SUnit *SU, int UpperBound, |
| bool &HasLoop) { |
| std::vector<const SUnit*> WorkList; |
| WorkList.reserve(SUnits.size()); |
| |
| WorkList.push_back(SU); |
| do { |
| SU = WorkList.back(); |
| WorkList.pop_back(); |
| Visited.set(SU->NodeNum); |
| for (int I = SU->Succs.size()-1; I >= 0; --I) { |
| int s = SU->Succs[I].getSUnit()->NodeNum; |
| if (Node2Index[s] == UpperBound) { |
| HasLoop = true; |
| return; |
| } |
| // Visit successors if not already and in affected region. |
| if (!Visited.test(s) && Node2Index[s] < UpperBound) { |
| WorkList.push_back(SU->Succs[I].getSUnit()); |
| } |
| } |
| } while (!WorkList.empty()); |
| } |
| |
| /// Shift - Renumber the nodes so that the topological ordering is |
| /// preserved. |
| void ScheduleDAGTopologicalSort::Shift(BitVector& Visited, int LowerBound, |
| int UpperBound) { |
| std::vector<int> L; |
| int shift = 0; |
| int i; |
| |
| for (i = LowerBound; i <= UpperBound; ++i) { |
| // w is node at topological index i. |
| int w = Index2Node[i]; |
| if (Visited.test(w)) { |
| // Unmark. |
| Visited.reset(w); |
| L.push_back(w); |
| shift = shift + 1; |
| } else { |
| Allocate(w, i - shift); |
| } |
| } |
| |
| for (unsigned j = 0; j < L.size(); ++j) { |
| Allocate(L[j], i - shift); |
| i = i + 1; |
| } |
| } |
| |
| |
| /// WillCreateCycle - Returns true if adding an edge from SU to TargetSU will |
| /// create a cycle. |
| bool ScheduleDAGTopologicalSort::WillCreateCycle(SUnit *SU, SUnit *TargetSU) { |
| if (IsReachable(TargetSU, SU)) |
| return true; |
| for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end(); |
| I != E; ++I) |
| if (I->isAssignedRegDep() && |
| IsReachable(TargetSU, I->getSUnit())) |
| return true; |
| return false; |
| } |
| |
| /// IsReachable - Checks if SU is reachable from TargetSU. |
| bool ScheduleDAGTopologicalSort::IsReachable(const SUnit *SU, |
| const SUnit *TargetSU) { |
| // If insertion of the edge SU->TargetSU would create a cycle |
| // then there is a path from TargetSU to SU. |
| int UpperBound, LowerBound; |
| LowerBound = Node2Index[TargetSU->NodeNum]; |
| UpperBound = Node2Index[SU->NodeNum]; |
| bool HasLoop = false; |
| // Is Ord(TargetSU) < Ord(SU) ? |
| if (LowerBound < UpperBound) { |
| Visited.reset(); |
| // There may be a path from TargetSU to SU. Check for it. |
| DFS(TargetSU, UpperBound, HasLoop); |
| } |
| return HasLoop; |
| } |
| |
| /// Allocate - assign the topological index to the node n. |
| void ScheduleDAGTopologicalSort::Allocate(int n, int index) { |
| Node2Index[n] = index; |
| Index2Node[index] = n; |
| } |
| |
| ScheduleDAGTopologicalSort:: |
| ScheduleDAGTopologicalSort(std::vector<SUnit> &sunits) : SUnits(sunits) {} |
| |
| ScheduleHazardRecognizer::~ScheduleHazardRecognizer() {} |