+
+#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)
+ cerr << "*** Scheduling failed! ***\n";
+ SUnits[i].dump(this);
+ cerr << "has not been scheduled!\n";
+ AnyNotSched = true;
+ }
+ if (SUnits[i].isScheduled &&
+ (isBottomUp ? SUnits[i].getHeight() : SUnits[i].getHeight()) >
+ unsigned(INT_MAX)) {
+ if (!AnyNotSched)
+ cerr << "*** Scheduling failed! ***\n";
+ SUnits[i].dump(this);
+ cerr << "has an unexpected "
+ << (isBottomUp ? "Height" : "Depth") << " value!\n";
+ AnyNotSched = true;
+ }
+ if (isBottomUp) {
+ if (SUnits[i].NumSuccsLeft != 0) {
+ if (!AnyNotSched)
+ cerr << "*** Scheduling failed! ***\n";
+ SUnits[i].dump(this);
+ cerr << "has successors left!\n";
+ AnyNotSched = true;
+ }
+ } else {
+ if (SUnits[i].NumPredsLeft != 0) {
+ if (!AnyNotSched)
+ cerr << "*** Scheduling failed! ***\n";
+ SUnits[i].dump(this);
+ cerr << "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 accomodate 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 accomodate 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() {}