X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FScheduleDAG.cpp;h=9a65071001709970097d3f04f8077bb38f59f3dd;hb=7d2f2496c1d263eecdc104fd72e847a31d8695b9;hp=046d3379a64655a36e5d9c0e07a39f0ab8bbe16a;hpb=98adea11496400c8385b774b4d9f9acd4c99d254;p=oota-llvm.git diff --git a/lib/CodeGen/ScheduleDAG.cpp b/lib/CodeGen/ScheduleDAG.cpp index 046d3379a64..9a650710017 100644 --- a/lib/CodeGen/ScheduleDAG.cpp +++ b/lib/CodeGen/ScheduleDAG.cpp @@ -14,210 +14,338 @@ #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 using namespace llvm; -ScheduleDAG::ScheduleDAG(SelectionDAG *dag, MachineBasicBlock *bb, - const TargetMachine &tm) - : DAG(dag), BB(bb), TM(tm), MRI(BB->getParent()->getRegInfo()) { - TII = TM.getInstrInfo(); - MF = BB->getParent(); - TRI = TM.getRegisterInfo(); - TLI = TM.getTargetLowering(); - ConstPool = MF->getConstantPool(); +#ifndef NDEBUG +static cl::opt 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() {} -/// CalculateDepths - compute depths using algorithms for the longest -/// paths in the DAG -void ScheduleDAG::CalculateDepths() { - unsigned DAGSize = SUnits.size(); - std::vector WorkList; - WorkList.reserve(DAGSize); +/// Clear the DAG state (e.g. between scheduling regions). +void ScheduleDAG::clearDAG() { + SUnits.clear(); + EntrySU = SUnit(); + ExitSU = SUnit(); +} - // Initialize the data structures - for (unsigned i = 0, e = DAGSize; i != e; ++i) { - SUnit *SU = &SUnits[i]; - unsigned Degree = SU->Preds.size(); - // Temporarily use the Depth field as scratch space for the degree count. - SU->Depth = Degree; +/// getInstrDesc helper to handle SDNodes. +const MCInstrDesc *ScheduleDAG::getNodeDesc(const SDNode *Node) const { + if (!Node || !Node->isMachineOpcode()) return NULL; + return &TII->get(Node->getMachineOpcode()); +} - // Is it a node without dependencies? - if (Degree == 0) { - assert(SU->Preds.empty() && "SUnit should have no predecessors"); - // Collect leaf nodes - WorkList.push_back(SU); +/// 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::iterator I = Preds.begin(), E = Preds.end(); + I != E; ++I) { + if (I->overlaps(D)) { + // Extend the latency if needed. Equivalent to removePred(I) + addPred(D). + if (I->getLatency() < D.getLatency()) { + SUnit *PredSU = I->getSUnit(); + // Find the corresponding successor in N. + SDep ForwardD = *I; + ForwardD.setSUnit(this); + for (SmallVector::iterator II = PredSU->Succs.begin(), + EE = PredSU->Succs.end(); II != EE; ++II) { + if (*II == ForwardD) { + II->setLatency(D.getLatency()); + break; + } + } + I->setLatency(D.getLatency()); + } + 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; +} - // Process nodes in the topological order - while (!WorkList.empty()) { - SUnit *SU = WorkList.back(); - WorkList.pop_back(); - unsigned SUDepth = 0; - - // Use dynamic programming: - // When current node is being processed, all of its dependencies - // are already processed. - // So, just iterate over all predecessors and take the longest path - for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end(); - I != E; ++I) { - unsigned PredDepth = I->Dep->Depth; - if (PredDepth+1 > SUDepth) { - SUDepth = PredDepth + 1; +/// 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::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::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; } +} - SU->Depth = SUDepth; - - // Update degrees of all nodes depending on current SUnit - for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end(); - I != E; ++I) { - SUnit *SU = I->Dep; - if (!--SU->Depth) - // If all dependencies of the node are processed already, - // then the longest path for the node can be computed now - WorkList.push_back(SU); +void SUnit::setDepthDirty() { + if (!isDepthCurrent) return; + SmallVector 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()); } -/// CalculateHeights - compute heights using algorithms for the longest -/// paths in the DAG -void ScheduleDAG::CalculateHeights() { - unsigned DAGSize = SUnits.size(); - std::vector WorkList; - WorkList.reserve(DAGSize); +void SUnit::setHeightDirty() { + if (!isHeightCurrent) return; + SmallVector 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()); +} - // Initialize the data structures - for (unsigned i = 0, e = DAGSize; i != e; ++i) { - SUnit *SU = &SUnits[i]; - unsigned Degree = SU->Succs.size(); - // Temporarily use the Height field as scratch space for the degree count. - SU->Height = Degree; +/// 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; +} - // Is it a node without dependencies? - if (Degree == 0) { - assert(SU->Succs.empty() && "Something wrong"); - assert(WorkList.empty() && "Should be empty"); - // Collect leaf nodes - WorkList.push_back(SU); - } - } +/// 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; +} - // Process nodes in the topological order - while (!WorkList.empty()) { - SUnit *SU = WorkList.back(); - WorkList.pop_back(); - unsigned SUHeight = 0; +/// ComputeDepth - Calculate the maximal path from the node to the exit. +/// +void SUnit::ComputeDepth() { + SmallVector WorkList; + WorkList.push_back(this); + do { + SUnit *Cur = WorkList.back(); - // Use dynamic programming: - // When current node is being processed, all of its dependencies - // are already processed. - // So, just iterate over all successors and take the longest path - for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end(); - I != E; ++I) { - unsigned SuccHeight = I->Dep->Height; - if (SuccHeight+1 > SUHeight) { - SUHeight = SuccHeight + 1; + 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); } } - SU->Height = SUHeight; - - // Update degrees of all nodes depending on current SUnit - for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end(); - I != E; ++I) { - SUnit *SU = I->Dep; - if (!--SU->Height) - // If all dependencies of the node are processed already, - // then the longest path for the node can be computed now - WorkList.push_back(SU); + if (Done) { + WorkList.pop_back(); + if (MaxPredDepth != Cur->Depth) { + Cur->setDepthDirty(); + Cur->Depth = MaxPredDepth; + } + Cur->isDepthCurrent = true; } - } + } while (!WorkList.empty()); } -/// 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 - cerr << "**** NOOP ****\n"; - } -} +/// ComputeHeight - Calculate the maximal path from the node to the entry. +/// +void SUnit::ComputeHeight() { + SmallVector 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); + } + } -/// Run - perform scheduling. -/// -void ScheduleDAG::Run() { - Schedule(); - - DOUT << "*** Final schedule ***\n"; - DEBUG(dumpSchedule()); - DOUT << "\n"; + if (Done) { + WorkList.pop_back(); + if (MaxSuccHeight != Cur->Height) { + Cur->setHeightDirty(); + Cur->Height = MaxSuccHeight; + } + Cur->isHeightCurrent = true; + } + } while (!WorkList.empty()); } +#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) /// 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 { - cerr << "SU(" << NodeNum << "): "; + dbgs() << "SU(" << NodeNum << "): "; G->dumpNode(this); } void SUnit::dumpAll(const ScheduleDAG *G) const { dump(G); - cerr << " # preds left : " << NumPredsLeft << "\n"; - cerr << " # succs left : " << NumSuccsLeft << "\n"; - cerr << " Latency : " << Latency << "\n"; - cerr << " Depth : " << Depth << "\n"; - cerr << " Height : " << Height << "\n"; + 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) { - cerr << " Predecessors:\n"; + dbgs() << " Predecessors:\n"; for (SUnit::const_succ_iterator I = Preds.begin(), E = Preds.end(); I != E; ++I) { - if (I->isCtrl) - cerr << " ch #"; - else - cerr << " val #"; - cerr << I->Dep << " - SU(" << I->Dep->NodeNum << ")"; - if (I->isArtificial) - cerr << " *"; - cerr << "\n"; + 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() << "SU(" << I->getSUnit()->NodeNum << ")"; + if (I->isArtificial()) + dbgs() << " *"; + dbgs() << ": Latency=" << I->getLatency(); + if (I->isAssignedRegDep()) + dbgs() << " Reg=" << PrintReg(I->getReg(), G->TRI); + dbgs() << "\n"; } } if (Succs.size() != 0) { - cerr << " Successors:\n"; + dbgs() << " Successors:\n"; for (SUnit::const_succ_iterator I = Succs.begin(), E = Succs.end(); I != E; ++I) { - if (I->isCtrl) - cerr << " ch #"; - else - cerr << " val #"; - cerr << I->Dep << " - SU(" << I->Dep->NodeNum << ")"; - if (I->isArtificial) - cerr << " *"; - cerr << "\n"; + 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() << "SU(" << I->getSUnit()->NodeNum << ")"; + if (I->isArtificial()) + dbgs() << " *"; + dbgs() << ": Latency=" << I->getLatency(); + dbgs() << "\n"; } } - cerr << "\n"; + dbgs() << "\n"; } +#endif #ifndef NDEBUG -/// VerifySchedule - Verify that all SUnits were scheduled and that -/// their state is consistent. +/// VerifyScheduledDAG - Verify that all SUnits were scheduled and that +/// their state is consistent. Return the number of scheduled nodes. /// -void ScheduleDAG::VerifySchedule(bool isBottomUp) { +unsigned ScheduleDAG::VerifyScheduledDAG(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) { @@ -225,41 +353,245 @@ void ScheduleDAG::VerifySchedule(bool isBottomUp) { continue; } if (!AnyNotSched) - cerr << "*** Scheduling failed! ***\n"; + dbgs() << "*** Scheduling failed! ***\n"; SUnits[i].dump(this); - cerr << "has not been scheduled!\n"; + dbgs() << "has not been scheduled!\n"; AnyNotSched = true; } - if (SUnits[i].isScheduled && SUnits[i].Cycle > (unsigned)INT_MAX) { + if (SUnits[i].isScheduled && + (isBottomUp ? SUnits[i].getHeight() : SUnits[i].getDepth()) > + unsigned(INT_MAX)) { if (!AnyNotSched) - cerr << "*** Scheduling failed! ***\n"; + dbgs() << "*** Scheduling failed! ***\n"; SUnits[i].dump(this); - cerr << "has an unexpected Cycle value!\n"; + dbgs() << "has an unexpected " + << (isBottomUp ? "Height" : "Depth") << " value!\n"; AnyNotSched = true; } if (isBottomUp) { if (SUnits[i].NumSuccsLeft != 0) { if (!AnyNotSched) - cerr << "*** Scheduling failed! ***\n"; + dbgs() << "*** Scheduling failed! ***\n"; SUnits[i].dump(this); - cerr << "has successors left!\n"; + dbgs() << "has successors left!\n"; AnyNotSched = true; } } else { if (SUnits[i].NumPredsLeft != 0) { if (!AnyNotSched) - cerr << "*** Scheduling failed! ***\n"; + dbgs() << "*** Scheduling failed! ***\n"; SUnits[i].dump(this); - cerr << "has predecessors left!\n"; + 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!"); + return SUnits.size() - DeadNodes; } #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 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 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 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 &sunits) : SUnits(sunits) {} + +ScheduleHazardRecognizer::~ScheduleHazardRecognizer() {}