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/Debug.h"
30 typedef unsigned NodeId;
31 typedef unsigned EdgeId;
33 /// @brief Returns a value representing an invalid (non-existent) node.
34 static NodeId invalidNodeId() {
35 return std::numeric_limits<NodeId>::max();
38 /// @brief Returns a value representing an invalid (non-existent) edge.
39 static EdgeId invalidEdgeId() {
40 return std::numeric_limits<EdgeId>::max();
45 /// Instances of this class describe PBQP problems.
47 template <typename SolverT>
48 class Graph : public GraphBase {
50 typedef typename SolverT::CostAllocator CostAllocator;
52 typedef typename SolverT::RawVector RawVector;
53 typedef typename SolverT::RawMatrix RawMatrix;
54 typedef typename SolverT::Vector Vector;
55 typedef typename SolverT::Matrix Matrix;
56 typedef typename CostAllocator::VectorPtr VectorPtr;
57 typedef typename CostAllocator::MatrixPtr MatrixPtr;
58 typedef typename SolverT::NodeMetadata NodeMetadata;
59 typedef typename SolverT::EdgeMetadata EdgeMetadata;
60 typedef typename SolverT::GraphMetadata GraphMetadata;
66 typedef std::vector<EdgeId> AdjEdgeList;
67 typedef AdjEdgeList::size_type AdjEdgeIdx;
68 typedef AdjEdgeList::const_iterator AdjEdgeItr;
70 static AdjEdgeIdx getInvalidAdjEdgeIdx() {
71 return std::numeric_limits<AdjEdgeIdx>::max();
74 NodeEntry(VectorPtr Costs) : Costs(Costs) {}
76 AdjEdgeIdx addAdjEdgeId(EdgeId EId) {
77 AdjEdgeIdx Idx = AdjEdgeIds.size();
78 AdjEdgeIds.push_back(EId);
82 void removeAdjEdgeId(Graph &G, NodeId ThisNId, AdjEdgeIdx Idx) {
83 // Swap-and-pop for fast removal.
84 // 1) Update the adj index of the edge currently at back().
85 // 2) Move last Edge down to Idx.
87 // If Idx == size() - 1 then the setAdjEdgeIdx and swap are
88 // redundant, but both operations are cheap.
89 G.getEdge(AdjEdgeIds.back()).setAdjEdgeIdx(ThisNId, Idx);
90 AdjEdgeIds[Idx] = AdjEdgeIds.back();
91 AdjEdgeIds.pop_back();
94 const AdjEdgeList& getAdjEdgeIds() const { return AdjEdgeIds; }
97 NodeMetadata Metadata;
99 AdjEdgeList AdjEdgeIds;
104 EdgeEntry(NodeId N1Id, NodeId N2Id, MatrixPtr Costs)
108 ThisEdgeAdjIdxs[0] = NodeEntry::getInvalidAdjEdgeIdx();
109 ThisEdgeAdjIdxs[1] = NodeEntry::getInvalidAdjEdgeIdx();
113 NIds[0] = NIds[1] = Graph::invalidNodeId();
114 ThisEdgeAdjIdxs[0] = ThisEdgeAdjIdxs[1] =
115 NodeEntry::getInvalidAdjEdgeIdx();
119 void connectToN(Graph &G, EdgeId ThisEdgeId, unsigned NIdx) {
120 assert(ThisEdgeAdjIdxs[NIdx] == NodeEntry::getInvalidAdjEdgeIdx() &&
121 "Edge already connected to NIds[NIdx].");
122 NodeEntry &N = G.getNode(NIds[NIdx]);
123 ThisEdgeAdjIdxs[NIdx] = N.addAdjEdgeId(ThisEdgeId);
126 void connectTo(Graph &G, EdgeId ThisEdgeId, NodeId NId) {
128 connectToN(G, ThisEdgeId, 0);
130 assert(NId == NIds[1] && "Edge does not connect NId.");
131 connectToN(G, ThisEdgeId, 1);
135 void connect(Graph &G, EdgeId ThisEdgeId) {
136 connectToN(G, ThisEdgeId, 0);
137 connectToN(G, ThisEdgeId, 1);
140 void setAdjEdgeIdx(NodeId NId, typename NodeEntry::AdjEdgeIdx NewIdx) {
142 ThisEdgeAdjIdxs[0] = NewIdx;
144 assert(NId == NIds[1] && "Edge not connected to NId");
145 ThisEdgeAdjIdxs[1] = NewIdx;
149 void disconnectFromN(Graph &G, unsigned NIdx) {
150 assert(ThisEdgeAdjIdxs[NIdx] != NodeEntry::getInvalidAdjEdgeIdx() &&
151 "Edge not connected to NIds[NIdx].");
152 NodeEntry &N = G.getNode(NIds[NIdx]);
153 N.removeAdjEdgeId(G, NIds[NIdx], ThisEdgeAdjIdxs[NIdx]);
154 ThisEdgeAdjIdxs[NIdx] = NodeEntry::getInvalidAdjEdgeIdx();
157 void disconnectFrom(Graph &G, NodeId NId) {
159 disconnectFromN(G, 0);
161 assert(NId == NIds[1] && "Edge does not connect NId");
162 disconnectFromN(G, 1);
166 NodeId getN1Id() const { return NIds[0]; }
167 NodeId getN2Id() const { return NIds[1]; }
169 EdgeMetadata Metadata;
172 typename NodeEntry::AdjEdgeIdx ThisEdgeAdjIdxs[2];
175 // ----- MEMBERS -----
177 GraphMetadata Metadata;
178 CostAllocator CostAlloc;
181 typedef std::vector<NodeEntry> NodeVector;
182 typedef std::vector<NodeId> FreeNodeVector;
184 FreeNodeVector FreeNodeIds;
186 typedef std::vector<EdgeEntry> EdgeVector;
187 typedef std::vector<EdgeId> FreeEdgeVector;
189 FreeEdgeVector FreeEdgeIds;
191 // ----- INTERNAL METHODS -----
193 NodeEntry& getNode(NodeId NId) { return Nodes[NId]; }
194 const NodeEntry& getNode(NodeId NId) const { return Nodes[NId]; }
196 EdgeEntry& getEdge(EdgeId EId) { return Edges[EId]; }
197 const EdgeEntry& getEdge(EdgeId EId) const { return Edges[EId]; }
199 NodeId addConstructedNode(NodeEntry N) {
201 if (!FreeNodeIds.empty()) {
202 NId = FreeNodeIds.back();
203 FreeNodeIds.pop_back();
204 Nodes[NId] = std::move(N);
207 Nodes.push_back(std::move(N));
212 EdgeId addConstructedEdge(EdgeEntry E) {
213 assert(findEdge(E.getN1Id(), E.getN2Id()) == invalidEdgeId() &&
214 "Attempt to add duplicate edge.");
216 if (!FreeEdgeIds.empty()) {
217 EId = FreeEdgeIds.back();
218 FreeEdgeIds.pop_back();
219 Edges[EId] = std::move(E);
222 Edges.push_back(std::move(E));
225 EdgeEntry &NE = getEdge(EId);
227 // Add the edge to the adjacency sets of its nodes.
228 NE.connect(*this, EId);
232 Graph(const Graph &Other) {}
233 void operator=(const Graph &Other) {}
237 typedef typename NodeEntry::AdjEdgeItr AdjEdgeItr;
241 typedef std::forward_iterator_tag iterator_category;
242 typedef NodeId value_type;
243 typedef int difference_type;
244 typedef NodeId* pointer;
245 typedef NodeId& reference;
247 NodeItr(NodeId CurNId, const Graph &G)
248 : CurNId(CurNId), EndNId(G.Nodes.size()), FreeNodeIds(G.FreeNodeIds) {
249 this->CurNId = findNextInUse(CurNId); // Move to first in-use node id
252 bool operator==(const NodeItr &O) const { return CurNId == O.CurNId; }
253 bool operator!=(const NodeItr &O) const { return !(*this == O); }
254 NodeItr& operator++() { CurNId = findNextInUse(++CurNId); return *this; }
255 NodeId operator*() const { return CurNId; }
258 NodeId findNextInUse(NodeId NId) const {
259 while (NId < EndNId &&
260 std::find(FreeNodeIds.begin(), FreeNodeIds.end(), NId) !=
267 NodeId CurNId, EndNId;
268 const FreeNodeVector &FreeNodeIds;
273 EdgeItr(EdgeId CurEId, const Graph &G)
274 : CurEId(CurEId), EndEId(G.Edges.size()), FreeEdgeIds(G.FreeEdgeIds) {
275 this->CurEId = findNextInUse(CurEId); // Move to first in-use edge id
278 bool operator==(const EdgeItr &O) const { return CurEId == O.CurEId; }
279 bool operator!=(const EdgeItr &O) const { return !(*this == O); }
280 EdgeItr& operator++() { CurEId = findNextInUse(++CurEId); return *this; }
281 EdgeId operator*() const { return CurEId; }
284 EdgeId findNextInUse(EdgeId EId) const {
285 while (EId < EndEId &&
286 std::find(FreeEdgeIds.begin(), FreeEdgeIds.end(), EId) !=
293 EdgeId CurEId, EndEId;
294 const FreeEdgeVector &FreeEdgeIds;
299 NodeIdSet(const Graph &G) : G(G) { }
300 NodeItr begin() const { return NodeItr(0, G); }
301 NodeItr end() const { return NodeItr(G.Nodes.size(), G); }
302 bool empty() const { return G.Nodes.empty(); }
303 typename NodeVector::size_type size() const {
304 return G.Nodes.size() - G.FreeNodeIds.size();
312 EdgeIdSet(const Graph &G) : G(G) { }
313 EdgeItr begin() const { return EdgeItr(0, G); }
314 EdgeItr end() const { return EdgeItr(G.Edges.size(), G); }
315 bool empty() const { return G.Edges.empty(); }
316 typename NodeVector::size_type size() const {
317 return G.Edges.size() - G.FreeEdgeIds.size();
325 AdjEdgeIdSet(const NodeEntry &NE) : NE(NE) { }
326 typename NodeEntry::AdjEdgeItr begin() const {
327 return NE.getAdjEdgeIds().begin();
329 typename NodeEntry::AdjEdgeItr end() const {
330 return NE.getAdjEdgeIds().end();
332 bool empty() const { return NE.getAdjEdgeIds().empty(); }
333 typename NodeEntry::AdjEdgeList::size_type size() const {
334 return NE.getAdjEdgeIds().size();
340 /// @brief Construct an empty PBQP graph.
341 Graph() : Solver(nullptr) {}
343 /// @brief Construct an empty PBQP graph with the given graph metadata.
344 Graph(GraphMetadata Metadata) : Metadata(Metadata), Solver(nullptr) {}
346 /// @brief Get a reference to the graph metadata.
347 GraphMetadata& getMetadata() { return Metadata; }
349 /// @brief Get a const-reference to the graph metadata.
350 const GraphMetadata& getMetadata() const { return Metadata; }
352 /// @brief Lock this graph to the given solver instance in preparation
353 /// for running the solver. This method will call solver.handleAddNode for
354 /// each node in the graph, and handleAddEdge for each edge, to give the
355 /// solver an opportunity to set up any requried metadata.
356 void setSolver(SolverT &S) {
357 assert(!Solver && "Solver already set. Call unsetSolver().");
359 for (auto NId : nodeIds())
360 Solver->handleAddNode(NId);
361 for (auto EId : edgeIds())
362 Solver->handleAddEdge(EId);
365 /// @brief Release from solver instance.
367 assert(Solver && "Solver not set.");
371 /// @brief Add a node with the given costs.
372 /// @param Costs Cost vector for the new node.
373 /// @return Node iterator for the added node.
374 template <typename OtherVectorT>
375 NodeId addNode(OtherVectorT Costs) {
376 // Get cost vector from the problem domain
377 VectorPtr AllocatedCosts = CostAlloc.getVector(std::move(Costs));
378 NodeId NId = addConstructedNode(NodeEntry(AllocatedCosts));
380 Solver->handleAddNode(NId);
384 /// @brief Add an edge between the given nodes with the given costs.
385 /// @param N1Id First node.
386 /// @param N2Id Second node.
387 /// @return Edge iterator for the added edge.
388 template <typename OtherVectorT>
389 EdgeId addEdge(NodeId N1Id, NodeId N2Id, OtherVectorT Costs) {
390 assert(getNodeCosts(N1Id).getLength() == Costs.getRows() &&
391 getNodeCosts(N2Id).getLength() == Costs.getCols() &&
392 "Matrix dimensions mismatch.");
393 // Get cost matrix from the problem domain.
394 MatrixPtr AllocatedCosts = CostAlloc.getMatrix(std::move(Costs));
395 EdgeId EId = addConstructedEdge(EdgeEntry(N1Id, N2Id, AllocatedCosts));
397 Solver->handleAddEdge(EId);
401 /// @brief Returns true if the graph is empty.
402 bool empty() const { return NodeIdSet(*this).empty(); }
404 NodeIdSet nodeIds() const { return NodeIdSet(*this); }
405 EdgeIdSet edgeIds() const { return EdgeIdSet(*this); }
407 AdjEdgeIdSet adjEdgeIds(NodeId NId) { return AdjEdgeIdSet(getNode(NId)); }
409 /// @brief Get the number of nodes in the graph.
410 /// @return Number of nodes in the graph.
411 unsigned getNumNodes() const { return NodeIdSet(*this).size(); }
413 /// @brief Get the number of edges in the graph.
414 /// @return Number of edges in the graph.
415 unsigned getNumEdges() const { return EdgeIdSet(*this).size(); }
417 /// @brief Set a node's cost vector.
418 /// @param NId Node to update.
419 /// @param Costs New costs to set.
420 template <typename OtherVectorT>
421 void setNodeCosts(NodeId NId, OtherVectorT Costs) {
422 VectorPtr AllocatedCosts = CostAlloc.getVector(std::move(Costs));
424 Solver->handleSetNodeCosts(NId, *AllocatedCosts);
425 getNode(NId).Costs = AllocatedCosts;
428 /// @brief Get a node's cost vector (const version).
429 /// @param NId Node id.
430 /// @return Node cost vector.
431 const Vector& getNodeCosts(NodeId NId) const { return *getNode(NId).Costs; }
433 NodeMetadata& getNodeMetadata(NodeId NId) {
434 return getNode(NId).Metadata;
437 const NodeMetadata& getNodeMetadata(NodeId NId) const {
438 return getNode(NId).Metadata;
441 typename NodeEntry::AdjEdgeList::size_type getNodeDegree(NodeId NId) const {
442 return getNode(NId).getAdjEdgeIds().size();
445 /// @brief Set an edge's cost matrix.
446 /// @param EId Edge id.
447 /// @param Costs New cost matrix.
448 template <typename OtherMatrixT>
449 void setEdgeCosts(EdgeId EId, OtherMatrixT Costs) {
450 MatrixPtr AllocatedCosts = CostAlloc.getMatrix(std::move(Costs));
452 Solver->handleSetEdgeCosts(EId, *AllocatedCosts);
453 getEdge(EId).Costs = AllocatedCosts;
456 /// @brief Get an edge's cost matrix (const version).
457 /// @param EId Edge id.
458 /// @return Edge cost matrix.
459 const Matrix& getEdgeCosts(EdgeId EId) const {
460 return *getEdge(EId).Costs;
463 EdgeMetadata& getEdgeMetadata(EdgeId NId) {
464 return getEdge(NId).Metadata;
467 const EdgeMetadata& getEdgeMetadata(EdgeId NId) const {
468 return getEdge(NId).Metadata;
471 /// @brief Get the first node connected to this edge.
472 /// @param EId Edge id.
473 /// @return The first node connected to the given edge.
474 NodeId getEdgeNode1Id(EdgeId EId) {
475 return getEdge(EId).getN1Id();
478 /// @brief Get the second node connected to this edge.
479 /// @param EId Edge id.
480 /// @return The second node connected to the given edge.
481 NodeId getEdgeNode2Id(EdgeId EId) {
482 return getEdge(EId).getN2Id();
485 /// @brief Get the "other" node connected to this edge.
486 /// @param EId Edge id.
487 /// @param NId Node id for the "given" node.
488 /// @return The iterator for the "other" node connected to this edge.
489 NodeId getEdgeOtherNodeId(EdgeId EId, NodeId NId) {
490 EdgeEntry &E = getEdge(EId);
491 if (E.getN1Id() == NId) {
497 /// @brief Get the edge connecting two nodes.
498 /// @param N1Id First node id.
499 /// @param N2Id Second node id.
500 /// @return An id for edge (N1Id, N2Id) if such an edge exists,
501 /// otherwise returns an invalid edge id.
502 EdgeId findEdge(NodeId N1Id, NodeId N2Id) {
503 for (auto AEId : adjEdgeIds(N1Id)) {
504 if ((getEdgeNode1Id(AEId) == N2Id) ||
505 (getEdgeNode2Id(AEId) == N2Id)) {
509 return invalidEdgeId();
512 /// @brief Remove a node from the graph.
513 /// @param NId Node id.
514 void removeNode(NodeId NId) {
516 Solver->handleRemoveNode(NId);
517 NodeEntry &N = getNode(NId);
518 // TODO: Can this be for-each'd?
519 for (AdjEdgeItr AEItr = N.adjEdgesBegin(),
520 AEEnd = N.adjEdgesEnd();
526 FreeNodeIds.push_back(NId);
529 /// @brief Disconnect an edge from the given node.
531 /// Removes the given edge from the adjacency list of the given node.
532 /// This operation leaves the edge in an 'asymmetric' state: It will no
533 /// longer appear in an iteration over the given node's (NId's) edges, but
534 /// will appear in an iteration over the 'other', unnamed node's edges.
536 /// This does not correspond to any normal graph operation, but exists to
537 /// support efficient PBQP graph-reduction based solvers. It is used to
538 /// 'effectively' remove the unnamed node from the graph while the solver
539 /// is performing the reduction. The solver will later call reconnectNode
540 /// to restore the edge in the named node's adjacency list.
542 /// Since the degree of a node is the number of connected edges,
543 /// disconnecting an edge from a node 'u' will cause the degree of 'u' to
546 /// A disconnected edge WILL still appear in an iteration over the graph
549 /// A disconnected edge should not be removed from the graph, it should be
550 /// reconnected first.
552 /// A disconnected edge can be reconnected by calling the reconnectEdge
554 void disconnectEdge(EdgeId EId, NodeId NId) {
556 Solver->handleDisconnectEdge(EId, NId);
558 EdgeEntry &E = getEdge(EId);
559 E.disconnectFrom(*this, NId);
562 /// @brief Convenience method to disconnect all neighbours from the given
564 void disconnectAllNeighborsFromNode(NodeId NId) {
565 for (auto AEId : adjEdgeIds(NId))
566 disconnectEdge(AEId, getEdgeOtherNodeId(AEId, NId));
569 /// @brief Re-attach an edge to its nodes.
571 /// Adds an edge that had been previously disconnected back into the
572 /// adjacency set of the nodes that the edge connects.
573 void reconnectEdge(EdgeId EId, NodeId NId) {
574 EdgeEntry &E = getEdge(EId);
575 E.connectTo(*this, EId, NId);
577 Solver->handleReconnectEdge(EId, NId);
580 /// @brief Remove an edge from the graph.
581 /// @param EId Edge id.
582 void removeEdge(EdgeId EId) {
584 Solver->handleRemoveEdge(EId);
585 EdgeEntry &E = getEdge(EId);
587 FreeEdgeIds.push_back(EId);
588 Edges[EId].invalidate();
591 /// @brief Remove all nodes and edges from the graph.
599 /// @brief Dump a graph to an output stream.
600 template <typename OStream>
601 void dumpToStream(OStream &OS) {
602 OS << nodeIds().size() << " " << edgeIds().size() << "\n";
604 for (auto NId : nodeIds()) {
605 const Vector& V = getNodeCosts(NId);
606 OS << "\n" << V.getLength() << "\n";
607 assert(V.getLength() != 0 && "Empty vector in graph.");
609 for (unsigned i = 1; i < V.getLength(); ++i) {
615 for (auto EId : edgeIds()) {
616 NodeId N1Id = getEdgeNode1Id(EId);
617 NodeId N2Id = getEdgeNode2Id(EId);
618 assert(N1Id != N2Id && "PBQP graphs shound not have self-edges.");
619 const Matrix& M = getEdgeCosts(EId);
620 OS << "\n" << N1Id << " " << N2Id << "\n"
621 << M.getRows() << " " << M.getCols() << "\n";
622 assert(M.getRows() != 0 && "No rows in matrix.");
623 assert(M.getCols() != 0 && "No cols in matrix.");
624 for (unsigned i = 0; i < M.getRows(); ++i) {
626 for (unsigned j = 1; j < M.getCols(); ++j) {
627 OS << " " << M[i][j];
634 /// @brief Dump this graph to dbgs().
636 dumpToStream(dbgs());
639 /// @brief Print a representation of this graph in DOT format.
640 /// @param OS Output stream to print on.
641 template <typename OStream>
642 void printDot(OStream &OS) {
644 for (auto NId : nodeIds()) {
645 OS << " node" << NId << " [ label=\""
646 << NId << ": " << getNodeCosts(NId) << "\" ]\n";
648 OS << " edge [ len=" << nodeIds().size() << " ]\n";
649 for (auto EId : edgeIds()) {
650 OS << " node" << getEdgeNode1Id(EId)
651 << " -- node" << getEdgeNode2Id(EId)
653 const Matrix &EdgeCosts = getEdgeCosts(EId);
654 for (unsigned i = 0; i < EdgeCosts.getRows(); ++i) {
655 OS << EdgeCosts.getRowAsVector(i) << "\\n";
666 #endif // LLVM_CODEGEN_PBQP_GRAPH_HPP