1 //===-------------------- Graph.h - PBQP Graph ------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
12 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_CODEGEN_PBQP_GRAPH_H
16 #define LLVM_CODEGEN_PBQP_GRAPH_H
18 #include "llvm/ADT/ilist.h"
19 #include "llvm/ADT/ilist_node.h"
20 #include "llvm/Support/Compiler.h"
29 typedef unsigned NodeId;
30 typedef unsigned EdgeId;
34 /// Instances of this class describe PBQP problems.
36 template <typename SolverT>
37 class Graph : public GraphBase {
39 typedef typename SolverT::CostAllocator CostAllocator;
41 typedef typename SolverT::RawVector RawVector;
42 typedef typename SolverT::RawMatrix RawMatrix;
43 typedef typename SolverT::Vector Vector;
44 typedef typename SolverT::Matrix Matrix;
45 typedef typename CostAllocator::VectorPtr VectorPtr;
46 typedef typename CostAllocator::MatrixPtr MatrixPtr;
47 typedef typename SolverT::NodeMetadata NodeMetadata;
48 typedef typename SolverT::EdgeMetadata EdgeMetadata;
54 typedef std::vector<EdgeId> AdjEdgeList;
55 typedef AdjEdgeList::size_type AdjEdgeIdx;
56 typedef AdjEdgeList::const_iterator AdjEdgeItr;
58 static AdjEdgeIdx getInvalidAdjEdgeIdx() {
59 return std::numeric_limits<AdjEdgeIdx>::max();
62 NodeEntry(VectorPtr Costs) : Costs(Costs) {}
64 AdjEdgeIdx addAdjEdgeId(EdgeId EId) {
65 AdjEdgeIdx Idx = AdjEdgeIds.size();
66 AdjEdgeIds.push_back(EId);
70 // If a swap is performed, returns the new EdgeId that must be
71 // updated, otherwise returns invalidEdgeId().
72 EdgeId removeAdjEdgeId(AdjEdgeIdx Idx) {
73 EdgeId EIdToUpdate = Graph::invalidEdgeId();
74 if (Idx < AdjEdgeIds.size() - 1) {
75 std::swap(AdjEdgeIds[Idx], AdjEdgeIds.back());
76 EIdToUpdate = AdjEdgeIds[Idx];
78 AdjEdgeIds.pop_back();
82 const AdjEdgeList& getAdjEdgeIds() const { return AdjEdgeIds; }
85 NodeMetadata Metadata;
87 AdjEdgeList AdjEdgeIds;
92 EdgeEntry(NodeId N1Id, NodeId N2Id, MatrixPtr Costs)
96 ThisEdgeAdjIdxs[0] = NodeEntry::getInvalidAdjEdgeIdx();
97 ThisEdgeAdjIdxs[1] = NodeEntry::getInvalidAdjEdgeIdx();
101 NIds[0] = NIds[1] = Graph::invalidNodeId();
102 ThisEdgeAdjIdxs[0] = ThisEdgeAdjIdxs[1] =
103 NodeEntry::getInvalidAdjEdgeIdx();
107 void connectToN(Graph &G, EdgeId ThisEdgeId, unsigned NIdx) {
108 assert(ThisEdgeAdjIdxs[NIdx] == NodeEntry::getInvalidAdjEdgeIdx() &&
109 "Edge already connected to NIds[NIdx].");
110 NodeEntry &N = G.getNode(NIds[NIdx]);
111 ThisEdgeAdjIdxs[NIdx] = N.addAdjEdgeId(ThisEdgeId);
114 void connectTo(Graph &G, EdgeId ThisEdgeId, NodeId NId) {
116 connectToN(G, ThisEdgeId, 0);
118 assert(NId == NIds[1] && "Edge does not connect NId.");
119 connectToN(G, ThisEdgeId, 1);
123 void connect(Graph &G, EdgeId ThisEdgeId) {
124 connectToN(G, ThisEdgeId, 0);
125 connectToN(G, ThisEdgeId, 1);
128 void updateAdjEdgeIdx(NodeId NId, typename NodeEntry::AdjEdgeIdx NewIdx) {
130 ThisEdgeAdjIdxs[0] = NewIdx;
132 assert(NId == NIds[1] && "Edge not connected to NId");
133 ThisEdgeAdjIdxs[1] = NewIdx;
137 void disconnectFromN(Graph &G, unsigned NIdx) {
138 assert(ThisEdgeAdjIdxs[NIdx] != NodeEntry::getInvalidAdjEdgeIdx() &&
139 "Edge not connected to NIds[NIdx].");
140 NodeEntry &N = G.getNode(NIds[NIdx]);
141 EdgeId EIdToUpdate = N.removeAdjEdgeId(ThisEdgeAdjIdxs[NIdx]);
142 if (EIdToUpdate != Graph::invalidEdgeId())
143 G.getEdge(EIdToUpdate).updateAdjEdgeIdx(NIds[NIdx], ThisEdgeAdjIdxs[NIdx]);
144 ThisEdgeAdjIdxs[NIdx] = NodeEntry::getInvalidAdjEdgeIdx();
147 void disconnectFrom(Graph &G, NodeId NId) {
149 disconnectFromN(G, 0);
151 assert(NId == NIds[1] && "Edge does not connect NId");
152 disconnectFromN(G, 1);
156 NodeId getN1Id() const { return NIds[0]; }
157 NodeId getN2Id() const { return NIds[1]; }
159 EdgeMetadata Metadata;
162 typename NodeEntry::AdjEdgeIdx ThisEdgeAdjIdxs[2];
165 // ----- MEMBERS -----
167 CostAllocator CostAlloc;
170 typedef std::vector<NodeEntry> NodeVector;
171 typedef std::vector<NodeId> FreeNodeVector;
173 FreeNodeVector FreeNodeIds;
175 typedef std::vector<EdgeEntry> EdgeVector;
176 typedef std::vector<EdgeId> FreeEdgeVector;
178 FreeEdgeVector FreeEdgeIds;
180 // ----- INTERNAL METHODS -----
182 NodeEntry& getNode(NodeId NId) { return Nodes[NId]; }
183 const NodeEntry& getNode(NodeId NId) const { return Nodes[NId]; }
185 EdgeEntry& getEdge(EdgeId EId) { return Edges[EId]; }
186 const EdgeEntry& getEdge(EdgeId EId) const { return Edges[EId]; }
188 NodeId addConstructedNode(const NodeEntry &N) {
190 if (!FreeNodeIds.empty()) {
191 NId = FreeNodeIds.back();
192 FreeNodeIds.pop_back();
193 Nodes[NId] = std::move(N);
196 Nodes.push_back(std::move(N));
201 EdgeId addConstructedEdge(const EdgeEntry &E) {
202 assert(findEdge(E.getN1Id(), E.getN2Id()) == invalidEdgeId() &&
203 "Attempt to add duplicate edge.");
205 if (!FreeEdgeIds.empty()) {
206 EId = FreeEdgeIds.back();
207 FreeEdgeIds.pop_back();
208 Edges[EId] = std::move(E);
211 Edges.push_back(std::move(E));
214 EdgeEntry &NE = getEdge(EId);
216 // Add the edge to the adjacency sets of its nodes.
217 NE.connect(*this, EId);
221 Graph(const Graph &Other) {}
222 void operator=(const Graph &Other) {}
226 typedef typename NodeEntry::AdjEdgeItr AdjEdgeItr;
230 NodeItr(NodeId CurNId, const Graph &G)
231 : CurNId(CurNId), EndNId(G.Nodes.size()), FreeNodeIds(G.FreeNodeIds) {
232 this->CurNId = findNextInUse(CurNId); // Move to first in-use node id
235 bool operator==(const NodeItr &O) const { return CurNId == O.CurNId; }
236 bool operator!=(const NodeItr &O) const { return !(*this == O); }
237 NodeItr& operator++() { CurNId = findNextInUse(++CurNId); return *this; }
238 NodeId operator*() const { return CurNId; }
241 NodeId findNextInUse(NodeId NId) const {
242 while (NId < EndNId &&
243 std::find(FreeNodeIds.begin(), FreeNodeIds.end(), NId) !=
250 NodeId CurNId, EndNId;
251 const FreeNodeVector &FreeNodeIds;
256 EdgeItr(EdgeId CurEId, const Graph &G)
257 : CurEId(CurEId), EndEId(G.Edges.size()), FreeEdgeIds(G.FreeEdgeIds) {
258 this->CurEId = findNextInUse(CurEId); // Move to first in-use edge id
261 bool operator==(const EdgeItr &O) const { return CurEId == O.CurEId; }
262 bool operator!=(const EdgeItr &O) const { return !(*this == O); }
263 EdgeItr& operator++() { CurEId = findNextInUse(++CurEId); return *this; }
264 EdgeId operator*() const { return CurEId; }
267 EdgeId findNextInUse(EdgeId EId) const {
268 while (EId < EndEId &&
269 std::find(FreeEdgeIds.begin(), FreeEdgeIds.end(), EId) !=
276 EdgeId CurEId, EndEId;
277 const FreeEdgeVector &FreeEdgeIds;
282 NodeIdSet(const Graph &G) : G(G) { }
283 NodeItr begin() const { return NodeItr(0, G); }
284 NodeItr end() const { return NodeItr(G.Nodes.size(), G); }
285 bool empty() const { return G.Nodes.empty(); }
286 typename NodeVector::size_type size() const {
287 return G.Nodes.size() - G.FreeNodeIds.size();
295 EdgeIdSet(const Graph &G) : G(G) { }
296 EdgeItr begin() const { return EdgeItr(0, G); }
297 EdgeItr end() const { return EdgeItr(G.Edges.size(), G); }
298 bool empty() const { return G.Edges.empty(); }
299 typename NodeVector::size_type size() const {
300 return G.Edges.size() - G.FreeEdgeIds.size();
308 AdjEdgeIdSet(const NodeEntry &NE) : NE(NE) { }
309 typename NodeEntry::AdjEdgeItr begin() const {
310 return NE.getAdjEdgeIds().begin();
312 typename NodeEntry::AdjEdgeItr end() const {
313 return NE.getAdjEdgeIds().end();
315 bool empty() const { return NE.getAdjEdgeIds().empty(); }
316 typename NodeEntry::AdjEdgeList::size_type size() const {
317 return NE.getAdjEdgeIds().size();
323 /// \brief Construct an empty PBQP graph.
324 Graph() : Solver(nullptr) { }
326 /// \brief Lock this graph to the given solver instance in preparation
327 /// for running the solver. This method will call solver.handleAddNode for
328 /// each node in the graph, and handleAddEdge for each edge, to give the
329 /// solver an opportunity to set up any requried metadata.
330 void setSolver(SolverT &S) {
331 assert(Solver == nullptr && "Solver already set. Call unsetSolver().");
333 for (auto NId : nodeIds())
334 Solver->handleAddNode(NId);
335 for (auto EId : edgeIds())
336 Solver->handleAddEdge(EId);
339 /// \brief Release from solver instance.
341 assert(Solver != nullptr && "Solver not set.");
345 /// \brief Add a node with the given costs.
346 /// @param Costs Cost vector for the new node.
347 /// @return Node iterator for the added node.
348 template <typename OtherVectorT>
349 NodeId addNode(OtherVectorT Costs) {
350 // Get cost vector from the problem domain
351 VectorPtr AllocatedCosts = CostAlloc.getVector(std::move(Costs));
352 NodeId NId = addConstructedNode(NodeEntry(AllocatedCosts));
354 Solver->handleAddNode(NId);
358 /// \brief Add an edge between the given nodes with the given costs.
359 /// @param N1Id First node.
360 /// @param N2Id Second node.
361 /// @return Edge iterator for the added edge.
362 template <typename OtherVectorT>
363 EdgeId addEdge(NodeId N1Id, NodeId N2Id, OtherVectorT Costs) {
364 assert(getNodeCosts(N1Id).getLength() == Costs.getRows() &&
365 getNodeCosts(N2Id).getLength() == Costs.getCols() &&
366 "Matrix dimensions mismatch.");
367 // Get cost matrix from the problem domain.
368 MatrixPtr AllocatedCosts = CostAlloc.getMatrix(std::move(Costs));
369 EdgeId EId = addConstructedEdge(EdgeEntry(N1Id, N2Id, AllocatedCosts));
371 Solver->handleAddEdge(EId);
375 /// \brief Returns true if the graph is empty.
376 bool empty() const { return NodeIdSet(*this).empty(); }
378 NodeIdSet nodeIds() const { return NodeIdSet(*this); }
379 EdgeIdSet edgeIds() const { return EdgeIdSet(*this); }
381 AdjEdgeIdSet adjEdgeIds(NodeId NId) { return AdjEdgeIdSet(getNode(NId)); }
383 /// \brief Get the number of nodes in the graph.
384 /// @return Number of nodes in the graph.
385 unsigned getNumNodes() const { return NodeIdSet(*this).size(); }
387 /// \brief Get the number of edges in the graph.
388 /// @return Number of edges in the graph.
389 unsigned getNumEdges() const { return EdgeIdSet(*this).size(); }
391 /// \brief Set a node's cost vector.
392 /// @param NId Node to update.
393 /// @param Costs New costs to set.
394 template <typename OtherVectorT>
395 void setNodeCosts(NodeId NId, OtherVectorT Costs) {
396 VectorPtr AllocatedCosts = CostAlloc.getVector(std::move(Costs));
398 Solver->handleSetNodeCosts(NId, *AllocatedCosts);
399 getNode(NId).Costs = AllocatedCosts;
402 /// \brief Get a node's cost vector (const version).
403 /// @param NId Node id.
404 /// @return Node cost vector.
405 const Vector& getNodeCosts(NodeId NId) const {
406 return *getNode(NId).Costs;
409 NodeMetadata& getNodeMetadata(NodeId NId) {
410 return getNode(NId).Metadata;
413 const NodeMetadata& getNodeMetadata(NodeId NId) const {
414 return getNode(NId).Metadata;
417 typename NodeEntry::AdjEdgeList::size_type getNodeDegree(NodeId NId) const {
418 return getNode(NId).getAdjEdgeIds().size();
421 /// \brief Set an edge's cost matrix.
422 /// @param EId Edge id.
423 /// @param Costs New cost matrix.
424 template <typename OtherMatrixT>
425 void setEdgeCosts(EdgeId EId, OtherMatrixT Costs) {
426 MatrixPtr AllocatedCosts = CostAlloc.getMatrix(std::move(Costs));
428 Solver->handleSetEdgeCosts(EId, *AllocatedCosts);
429 getEdge(EId).Costs = AllocatedCosts;
432 /// \brief Get an edge's cost matrix (const version).
433 /// @param EId Edge id.
434 /// @return Edge cost matrix.
435 const Matrix& getEdgeCosts(EdgeId EId) const { return *getEdge(EId).Costs; }
437 EdgeMetadata& getEdgeMetadata(EdgeId NId) {
438 return getEdge(NId).Metadata;
441 const EdgeMetadata& getEdgeMetadata(EdgeId NId) const {
442 return getEdge(NId).Metadata;
445 /// \brief Get the first node connected to this edge.
446 /// @param EId Edge id.
447 /// @return The first node connected to the given edge.
448 NodeId getEdgeNode1Id(EdgeId EId) {
449 return getEdge(EId).getN1Id();
452 /// \brief Get the second node connected to this edge.
453 /// @param EId Edge id.
454 /// @return The second node connected to the given edge.
455 NodeId getEdgeNode2Id(EdgeId EId) {
456 return getEdge(EId).getN2Id();
459 /// \brief Get the "other" node connected to this edge.
460 /// @param EId Edge id.
461 /// @param NId Node id for the "given" node.
462 /// @return The iterator for the "other" node connected to this edge.
463 NodeId getEdgeOtherNodeId(EdgeId EId, NodeId NId) {
464 EdgeEntry &E = getEdge(EId);
465 if (E.getN1Id() == NId) {
471 /// \brief Returns a value representing an invalid (non-existant) node.
472 static NodeId invalidNodeId() {
473 return std::numeric_limits<NodeId>::max();
476 /// \brief Returns a value representing an invalid (non-existant) edge.
477 static EdgeId invalidEdgeId() {
478 return std::numeric_limits<EdgeId>::max();
481 /// \brief Get the edge connecting two nodes.
482 /// @param N1Id First node id.
483 /// @param N2Id Second node id.
484 /// @return An id for edge (N1Id, N2Id) if such an edge exists,
485 /// otherwise returns an invalid edge id.
486 EdgeId findEdge(NodeId N1Id, NodeId N2Id) {
487 for (auto AEId : adjEdgeIds(N1Id)) {
488 if ((getEdgeNode1Id(AEId) == N2Id) ||
489 (getEdgeNode2Id(AEId) == N2Id)) {
493 return invalidEdgeId();
496 /// \brief Remove a node from the graph.
497 /// @param NId Node id.
498 void removeNode(NodeId NId) {
500 Solver->handleRemoveNode(NId);
501 NodeEntry &N = getNode(NId);
502 // TODO: Can this be for-each'd?
503 for (AdjEdgeItr AEItr = N.adjEdgesBegin(),
504 AEEnd = N.adjEdgesEnd();
510 FreeNodeIds.push_back(NId);
513 /// \brief Disconnect an edge from the given node.
515 /// Removes the given edge from the adjacency list of the given node.
516 /// This operation leaves the edge in an 'asymmetric' state: It will no
517 /// longer appear in an iteration over the given node's (NId's) edges, but
518 /// will appear in an iteration over the 'other', unnamed node's edges.
520 /// This does not correspond to any normal graph operation, but exists to
521 /// support efficient PBQP graph-reduction based solvers. It is used to
522 /// 'effectively' remove the unnamed node from the graph while the solver
523 /// is performing the reduction. The solver will later call reconnectNode
524 /// to restore the edge in the named node's adjacency list.
526 /// Since the degree of a node is the number of connected edges,
527 /// disconnecting an edge from a node 'u' will cause the degree of 'u' to
530 /// A disconnected edge WILL still appear in an iteration over the graph
533 /// A disconnected edge should not be removed from the graph, it should be
534 /// reconnected first.
536 /// A disconnected edge can be reconnected by calling the reconnectEdge
538 void disconnectEdge(EdgeId EId, NodeId NId) {
540 Solver->handleDisconnectEdge(EId, NId);
542 EdgeEntry &E = getEdge(EId);
543 E.disconnectFrom(*this, NId);
546 /// \brief Convenience method to disconnect all neighbours from the given
548 void disconnectAllNeighborsFromNode(NodeId NId) {
549 for (auto AEId : adjEdgeIds(NId))
550 disconnectEdge(AEId, getEdgeOtherNodeId(AEId, NId));
553 /// \brief Re-attach an edge to its nodes.
555 /// Adds an edge that had been previously disconnected back into the
556 /// adjacency set of the nodes that the edge connects.
557 void reconnectEdge(EdgeId EId, NodeId NId) {
558 EdgeEntry &E = getEdge(EId);
559 E.connectTo(*this, EId, NId);
561 Solver->handleReconnectEdge(EId, NId);
564 /// \brief Remove an edge from the graph.
565 /// @param EId Edge id.
566 void removeEdge(EdgeId EId) {
568 Solver->handleRemoveEdge(EId);
569 EdgeEntry &E = getEdge(EId);
571 FreeEdgeIds.push_back(EId);
572 Edges[EId].invalidate();
575 /// \brief Remove all nodes and edges from the graph.
583 /// \brief Dump a graph to an output stream.
584 template <typename OStream>
585 void dump(OStream &OS) {
586 OS << nodeIds().size() << " " << edgeIds().size() << "\n";
588 for (auto NId : nodeIds()) {
589 const Vector& V = getNodeCosts(NId);
590 OS << "\n" << V.getLength() << "\n";
591 assert(V.getLength() != 0 && "Empty vector in graph.");
593 for (unsigned i = 1; i < V.getLength(); ++i) {
599 for (auto EId : edgeIds()) {
600 NodeId N1Id = getEdgeNode1Id(EId);
601 NodeId N2Id = getEdgeNode2Id(EId);
602 assert(N1Id != N2Id && "PBQP graphs shound not have self-edges.");
603 const Matrix& M = getEdgeCosts(EId);
604 OS << "\n" << N1Id << " " << N2Id << "\n"
605 << M.getRows() << " " << M.getCols() << "\n";
606 assert(M.getRows() != 0 && "No rows in matrix.");
607 assert(M.getCols() != 0 && "No cols in matrix.");
608 for (unsigned i = 0; i < M.getRows(); ++i) {
610 for (unsigned j = 1; j < M.getCols(); ++j) {
611 OS << " " << M[i][j];
618 /// \brief Print a representation of this graph in DOT format.
619 /// @param OS Output stream to print on.
620 template <typename OStream>
621 void printDot(OStream &OS) {
623 for (auto NId : nodeIds()) {
624 OS << " node" << NId << " [ label=\""
625 << NId << ": " << getNodeCosts(NId) << "\" ]\n";
627 OS << " edge [ len=" << nodeIds().size() << " ]\n";
628 for (auto EId : edgeIds()) {
629 OS << " node" << getEdgeNode1Id(EId)
630 << " -- node" << getEdgeNode2Id(EId)
632 const Matrix &EdgeCosts = getEdgeCosts(EId);
633 for (unsigned i = 0; i < EdgeCosts.getRows(); ++i) {
634 OS << EdgeCosts.getRowAsVector(i) << "\\n";
644 #endif // LLVM_CODEGEN_PBQP_GRAPH_HPP