Home | History | Annotate | Download | only in CodeGen 
      1 //===-- RegAllocPBQP.h ------------------------------------------*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file defines the PBQPBuilder interface, for classes which build PBQP
     11 // instances to represent register allocation problems, and the RegAllocPBQP
     12 // interface.
     13 //
     14 //===----------------------------------------------------------------------===//
     15 
     16 #ifndef LLVM_CODEGEN_REGALLOCPBQP_H
     17 #define LLVM_CODEGEN_REGALLOCPBQP_H
     18 
     19 #include "llvm/CodeGen/MachineFunctionPass.h"
     20 #include "llvm/CodeGen/PBQP/CostAllocator.h"
     21 #include "llvm/CodeGen/PBQP/ReductionRules.h"
     22 #include "llvm/CodeGen/PBQPRAConstraint.h"
     23 #include "llvm/Support/ErrorHandling.h"
     24 
     25 namespace llvm {
     26 
     27 class raw_ostream;
     28 
     29 namespace PBQP {
     30 namespace RegAlloc {
     31 
     32 /// @brief Spill option index.
     33 inline unsigned getSpillOptionIdx() { return 0; }
     34 
     35 /// \brief Metadata to speed allocatability test.
     36 ///
     37 /// Keeps track of the number of infinities in each row and column.
     38 class MatrixMetadata {
     39 private:
     40   MatrixMetadata(const MatrixMetadata&);
     41   void operator=(const MatrixMetadata&);
     42 public:
     43   MatrixMetadata(const Matrix& M)
     44     : WorstRow(0), WorstCol(0),
     45       UnsafeRows(new bool[M.getRows() - 1]()),
     46       UnsafeCols(new bool[M.getCols() - 1]()) {
     47 
     48     unsigned* ColCounts = new unsigned[M.getCols() - 1]();
     49 
     50     for (unsigned i = 1; i < M.getRows(); ++i) {
     51       unsigned RowCount = 0;
     52       for (unsigned j = 1; j < M.getCols(); ++j) {
     53         if (M[i][j] == std::numeric_limits<PBQPNum>::infinity()) {
     54           ++RowCount;
     55           ++ColCounts[j - 1];
     56           UnsafeRows[i - 1] = true;
     57           UnsafeCols[j - 1] = true;
     58         }
     59       }
     60       WorstRow = std::max(WorstRow, RowCount);
     61     }
     62     unsigned WorstColCountForCurRow =
     63       *std::max_element(ColCounts, ColCounts + M.getCols() - 1);
     64     WorstCol = std::max(WorstCol, WorstColCountForCurRow);
     65     delete[] ColCounts;
     66   }
     67 
     68   unsigned getWorstRow() const { return WorstRow; }
     69   unsigned getWorstCol() const { return WorstCol; }
     70   const bool* getUnsafeRows() const { return UnsafeRows.get(); }
     71   const bool* getUnsafeCols() const { return UnsafeCols.get(); }
     72 
     73 private:
     74   unsigned WorstRow, WorstCol;
     75   std::unique_ptr<bool[]> UnsafeRows;
     76   std::unique_ptr<bool[]> UnsafeCols;
     77 };
     78 
     79 /// \brief Holds a vector of the allowed physical regs for a vreg.
     80 class AllowedRegVector {
     81   friend hash_code hash_value(const AllowedRegVector &);
     82 public:
     83 
     84   AllowedRegVector() : NumOpts(0), Opts(nullptr) {}
     85 
     86   AllowedRegVector(const std::vector<unsigned> &OptVec)
     87     : NumOpts(OptVec.size()), Opts(new unsigned[NumOpts]) {
     88     std::copy(OptVec.begin(), OptVec.end(), Opts.get());
     89   }
     90 
     91   AllowedRegVector(const AllowedRegVector &Other)
     92     : NumOpts(Other.NumOpts), Opts(new unsigned[NumOpts]) {
     93     std::copy(Other.Opts.get(), Other.Opts.get() + NumOpts, Opts.get());
     94   }
     95 
     96   AllowedRegVector(AllowedRegVector &&Other)
     97     : NumOpts(std::move(Other.NumOpts)), Opts(std::move(Other.Opts)) {}
     98 
     99   AllowedRegVector& operator=(const AllowedRegVector &Other) {
    100     NumOpts = Other.NumOpts;
    101     Opts.reset(new unsigned[NumOpts]);
    102     std::copy(Other.Opts.get(), Other.Opts.get() + NumOpts, Opts.get());
    103     return *this;
    104   }
    105 
    106   AllowedRegVector& operator=(AllowedRegVector &&Other) {
    107     NumOpts = std::move(Other.NumOpts);
    108     Opts = std::move(Other.Opts);
    109     return *this;
    110   }
    111 
    112   unsigned size() const { return NumOpts; }
    113   unsigned operator[](size_t I) const { return Opts[I]; }
    114 
    115   bool operator==(const AllowedRegVector &Other) const {
    116     if (NumOpts != Other.NumOpts)
    117       return false;
    118     return std::equal(Opts.get(), Opts.get() + NumOpts, Other.Opts.get());
    119   }
    120 
    121   bool operator!=(const AllowedRegVector &Other) const {
    122     return !(*this == Other);
    123   }
    124 
    125 private:
    126   unsigned NumOpts;
    127   std::unique_ptr<unsigned[]> Opts;
    128 };
    129 
    130 inline hash_code hash_value(const AllowedRegVector &OptRegs) {
    131   unsigned *OStart = OptRegs.Opts.get();
    132   unsigned *OEnd = OptRegs.Opts.get() + OptRegs.NumOpts;
    133   return hash_combine(OptRegs.NumOpts,
    134                       hash_combine_range(OStart, OEnd));
    135 }
    136 
    137 /// \brief Holds graph-level metadata relevant to PBQP RA problems.
    138 class GraphMetadata {
    139 private:
    140   typedef ValuePool<AllowedRegVector> AllowedRegVecPool;
    141 public:
    142 
    143   typedef AllowedRegVecPool::PoolRef AllowedRegVecRef;
    144 
    145   GraphMetadata(MachineFunction &MF,
    146                 LiveIntervals &LIS,
    147                 MachineBlockFrequencyInfo &MBFI)
    148     : MF(MF), LIS(LIS), MBFI(MBFI) {}
    149 
    150   MachineFunction &MF;
    151   LiveIntervals &LIS;
    152   MachineBlockFrequencyInfo &MBFI;
    153 
    154   void setNodeIdForVReg(unsigned VReg, GraphBase::NodeId NId) {
    155     VRegToNodeId[VReg] = NId;
    156   }
    157 
    158   GraphBase::NodeId getNodeIdForVReg(unsigned VReg) const {
    159     auto VRegItr = VRegToNodeId.find(VReg);
    160     if (VRegItr == VRegToNodeId.end())
    161       return GraphBase::invalidNodeId();
    162     return VRegItr->second;
    163   }
    164 
    165   void eraseNodeIdForVReg(unsigned VReg) {
    166     VRegToNodeId.erase(VReg);
    167   }
    168 
    169   AllowedRegVecRef getAllowedRegs(AllowedRegVector Allowed) {
    170     return AllowedRegVecs.getValue(std::move(Allowed));
    171   }
    172 
    173 private:
    174   DenseMap<unsigned, GraphBase::NodeId> VRegToNodeId;
    175   AllowedRegVecPool AllowedRegVecs;
    176 };
    177 
    178 /// \brief Holds solver state and other metadata relevant to each PBQP RA node.
    179 class NodeMetadata {
    180 public:
    181   typedef RegAlloc::AllowedRegVector AllowedRegVector;
    182 
    183   // The node's reduction state. The order in this enum is important,
    184   // as it is assumed nodes can only progress up (i.e. towards being
    185   // optimally reducible) when reducing the graph.
    186   typedef enum {
    187     Unprocessed,
    188     NotProvablyAllocatable,
    189     ConservativelyAllocatable,
    190     OptimallyReducible
    191   } ReductionState;
    192 
    193   NodeMetadata()
    194     : RS(Unprocessed), NumOpts(0), DeniedOpts(0), OptUnsafeEdges(nullptr),
    195       VReg(0)
    196 #ifndef NDEBUG
    197       , everConservativelyAllocatable(false)
    198 #endif
    199       {}
    200 
    201   // FIXME: Re-implementing default behavior to work around MSVC. Remove once
    202   // MSVC synthesizes move constructors properly.
    203   NodeMetadata(const NodeMetadata &Other)
    204     : RS(Other.RS), NumOpts(Other.NumOpts), DeniedOpts(Other.DeniedOpts),
    205       OptUnsafeEdges(new unsigned[NumOpts]), VReg(Other.VReg),
    206       AllowedRegs(Other.AllowedRegs)
    207 #ifndef NDEBUG
    208       , everConservativelyAllocatable(Other.everConservativelyAllocatable)
    209 #endif
    210   {
    211     if (NumOpts > 0) {
    212       std::copy(&Other.OptUnsafeEdges[0], &Other.OptUnsafeEdges[NumOpts],
    213                 &OptUnsafeEdges[0]);
    214     }
    215   }
    216 
    217   // FIXME: Re-implementing default behavior to work around MSVC. Remove once
    218   // MSVC synthesizes move constructors properly.
    219   NodeMetadata(NodeMetadata &&Other)
    220     : RS(Other.RS), NumOpts(Other.NumOpts), DeniedOpts(Other.DeniedOpts),
    221       OptUnsafeEdges(std::move(Other.OptUnsafeEdges)), VReg(Other.VReg),
    222       AllowedRegs(std::move(Other.AllowedRegs))
    223 #ifndef NDEBUG
    224       , everConservativelyAllocatable(Other.everConservativelyAllocatable)
    225 #endif
    226   {}
    227 
    228   // FIXME: Re-implementing default behavior to work around MSVC. Remove once
    229   // MSVC synthesizes move constructors properly.
    230   NodeMetadata& operator=(const NodeMetadata &Other) {
    231     RS = Other.RS;
    232     NumOpts = Other.NumOpts;
    233     DeniedOpts = Other.DeniedOpts;
    234     OptUnsafeEdges.reset(new unsigned[NumOpts]);
    235     std::copy(Other.OptUnsafeEdges.get(), Other.OptUnsafeEdges.get() + NumOpts,
    236               OptUnsafeEdges.get());
    237     VReg = Other.VReg;
    238     AllowedRegs = Other.AllowedRegs;
    239 #ifndef NDEBUG
    240     everConservativelyAllocatable = Other.everConservativelyAllocatable;
    241 #endif
    242     return *this;
    243   }
    244 
    245   // FIXME: Re-implementing default behavior to work around MSVC. Remove once
    246   // MSVC synthesizes move constructors properly.
    247   NodeMetadata& operator=(NodeMetadata &&Other) {
    248     RS = Other.RS;
    249     NumOpts = Other.NumOpts;
    250     DeniedOpts = Other.DeniedOpts;
    251     OptUnsafeEdges = std::move(Other.OptUnsafeEdges);
    252     VReg = Other.VReg;
    253     AllowedRegs = std::move(Other.AllowedRegs);
    254 #ifndef NDEBUG
    255     everConservativelyAllocatable = Other.everConservativelyAllocatable;
    256 #endif
    257     return *this;
    258   }
    259 
    260   void setVReg(unsigned VReg) { this->VReg = VReg; }
    261   unsigned getVReg() const { return VReg; }
    262 
    263   void setAllowedRegs(GraphMetadata::AllowedRegVecRef AllowedRegs) {
    264     this->AllowedRegs = std::move(AllowedRegs);
    265   }
    266   const AllowedRegVector& getAllowedRegs() const { return *AllowedRegs; }
    267 
    268   void setup(const Vector& Costs) {
    269     NumOpts = Costs.getLength() - 1;
    270     OptUnsafeEdges = std::unique_ptr<unsigned[]>(new unsigned[NumOpts]());
    271   }
    272 
    273   ReductionState getReductionState() const { return RS; }
    274   void setReductionState(ReductionState RS) {
    275     assert(RS >= this->RS && "A node's reduction state can not be downgraded");
    276     this->RS = RS;
    277 
    278 #ifndef NDEBUG
    279     // Remember this state to assert later that a non-infinite register
    280     // option was available.
    281     if (RS == ConservativelyAllocatable)
    282       everConservativelyAllocatable = true;
    283 #endif
    284   }
    285 
    286 
    287   void handleAddEdge(const MatrixMetadata& MD, bool Transpose) {
    288     DeniedOpts += Transpose ? MD.getWorstRow() : MD.getWorstCol();
    289     const bool* UnsafeOpts =
    290       Transpose ? MD.getUnsafeCols() : MD.getUnsafeRows();
    291     for (unsigned i = 0; i < NumOpts; ++i)
    292       OptUnsafeEdges[i] += UnsafeOpts[i];
    293   }
    294 
    295   void handleRemoveEdge(const MatrixMetadata& MD, bool Transpose) {
    296     DeniedOpts -= Transpose ? MD.getWorstRow() : MD.getWorstCol();
    297     const bool* UnsafeOpts =
    298       Transpose ? MD.getUnsafeCols() : MD.getUnsafeRows();
    299     for (unsigned i = 0; i < NumOpts; ++i)
    300       OptUnsafeEdges[i] -= UnsafeOpts[i];
    301   }
    302 
    303   bool isConservativelyAllocatable() const {
    304     return (DeniedOpts < NumOpts) ||
    305       (std::find(&OptUnsafeEdges[0], &OptUnsafeEdges[NumOpts], 0) !=
    306        &OptUnsafeEdges[NumOpts]);
    307   }
    308 
    309 #ifndef NDEBUG
    310   bool wasConservativelyAllocatable() const {
    311     return everConservativelyAllocatable;
    312   }
    313 #endif
    314 
    315 private:
    316   ReductionState RS;
    317   unsigned NumOpts;
    318   unsigned DeniedOpts;
    319   std::unique_ptr<unsigned[]> OptUnsafeEdges;
    320   unsigned VReg;
    321   GraphMetadata::AllowedRegVecRef AllowedRegs;
    322 
    323 #ifndef NDEBUG
    324   bool everConservativelyAllocatable;
    325 #endif
    326 };
    327 
    328 class RegAllocSolverImpl {
    329 private:
    330   typedef MDMatrix<MatrixMetadata> RAMatrix;
    331 public:
    332   typedef PBQP::Vector RawVector;
    333   typedef PBQP::Matrix RawMatrix;
    334   typedef PBQP::Vector Vector;
    335   typedef RAMatrix     Matrix;
    336   typedef PBQP::PoolCostAllocator<Vector, Matrix> CostAllocator;
    337 
    338   typedef GraphBase::NodeId NodeId;
    339   typedef GraphBase::EdgeId EdgeId;
    340 
    341   typedef RegAlloc::NodeMetadata NodeMetadata;
    342   struct EdgeMetadata { };
    343   typedef RegAlloc::GraphMetadata GraphMetadata;
    344 
    345   typedef PBQP::Graph<RegAllocSolverImpl> Graph;
    346 
    347   RegAllocSolverImpl(Graph &G) : G(G) {}
    348 
    349   Solution solve() {
    350     G.setSolver(*this);
    351     Solution S;
    352     setup();
    353     S = backpropagate(G, reduce());
    354     G.unsetSolver();
    355     return S;
    356   }
    357 
    358   void handleAddNode(NodeId NId) {
    359     assert(G.getNodeCosts(NId).getLength() > 1 &&
    360            "PBQP Graph should not contain single or zero-option nodes");
    361     G.getNodeMetadata(NId).setup(G.getNodeCosts(NId));
    362   }
    363   void handleRemoveNode(NodeId NId) {}
    364   void handleSetNodeCosts(NodeId NId, const Vector& newCosts) {}
    365 
    366   void handleAddEdge(EdgeId EId) {
    367     handleReconnectEdge(EId, G.getEdgeNode1Id(EId));
    368     handleReconnectEdge(EId, G.getEdgeNode2Id(EId));
    369   }
    370 
    371   void handleRemoveEdge(EdgeId EId) {
    372     handleDisconnectEdge(EId, G.getEdgeNode1Id(EId));
    373     handleDisconnectEdge(EId, G.getEdgeNode2Id(EId));
    374   }
    375 
    376   void handleDisconnectEdge(EdgeId EId, NodeId NId) {
    377     NodeMetadata& NMd = G.getNodeMetadata(NId);
    378     const MatrixMetadata& MMd = G.getEdgeCosts(EId).getMetadata();
    379     NMd.handleRemoveEdge(MMd, NId == G.getEdgeNode2Id(EId));
    380     promote(NId, NMd);
    381   }
    382 
    383   void handleReconnectEdge(EdgeId EId, NodeId NId) {
    384     NodeMetadata& NMd = G.getNodeMetadata(NId);
    385     const MatrixMetadata& MMd = G.getEdgeCosts(EId).getMetadata();
    386     NMd.handleAddEdge(MMd, NId == G.getEdgeNode2Id(EId));
    387   }
    388 
    389   void handleUpdateCosts(EdgeId EId, const Matrix& NewCosts) {
    390     NodeId N1Id = G.getEdgeNode1Id(EId);
    391     NodeId N2Id = G.getEdgeNode2Id(EId);
    392     NodeMetadata& N1Md = G.getNodeMetadata(N1Id);
    393     NodeMetadata& N2Md = G.getNodeMetadata(N2Id);
    394     bool Transpose = N1Id != G.getEdgeNode1Id(EId);
    395 
    396     // Metadata are computed incrementally. First, update them
    397     // by removing the old cost.
    398     const MatrixMetadata& OldMMd = G.getEdgeCosts(EId).getMetadata();
    399     N1Md.handleRemoveEdge(OldMMd, Transpose);
    400     N2Md.handleRemoveEdge(OldMMd, !Transpose);
    401 
    402     // And update now the metadata with the new cost.
    403     const MatrixMetadata& MMd = NewCosts.getMetadata();
    404     N1Md.handleAddEdge(MMd, Transpose);
    405     N2Md.handleAddEdge(MMd, !Transpose);
    406 
    407     // As the metadata may have changed with the update, the nodes may have
    408     // become ConservativelyAllocatable or OptimallyReducible.
    409     promote(N1Id, N1Md);
    410     promote(N2Id, N2Md);
    411   }
    412 
    413 private:
    414 
    415   void promote(NodeId NId, NodeMetadata& NMd) {
    416     if (G.getNodeDegree(NId) == 3) {
    417       // This node is becoming optimally reducible.
    418       moveToOptimallyReducibleNodes(NId);
    419     } else if (NMd.getReductionState() ==
    420                NodeMetadata::NotProvablyAllocatable &&
    421                NMd.isConservativelyAllocatable()) {
    422       // This node just became conservatively allocatable.
    423       moveToConservativelyAllocatableNodes(NId);
    424     }
    425   }
    426 
    427   void removeFromCurrentSet(NodeId NId) {
    428     switch (G.getNodeMetadata(NId).getReductionState()) {
    429     case NodeMetadata::Unprocessed: break;
    430     case NodeMetadata::OptimallyReducible:
    431       assert(OptimallyReducibleNodes.find(NId) !=
    432              OptimallyReducibleNodes.end() &&
    433              "Node not in optimally reducible set.");
    434       OptimallyReducibleNodes.erase(NId);
    435       break;
    436     case NodeMetadata::ConservativelyAllocatable:
    437       assert(ConservativelyAllocatableNodes.find(NId) !=
    438              ConservativelyAllocatableNodes.end() &&
    439              "Node not in conservatively allocatable set.");
    440       ConservativelyAllocatableNodes.erase(NId);
    441       break;
    442     case NodeMetadata::NotProvablyAllocatable:
    443       assert(NotProvablyAllocatableNodes.find(NId) !=
    444              NotProvablyAllocatableNodes.end() &&
    445              "Node not in not-provably-allocatable set.");
    446       NotProvablyAllocatableNodes.erase(NId);
    447       break;
    448     }
    449   }
    450 
    451   void moveToOptimallyReducibleNodes(NodeId NId) {
    452     removeFromCurrentSet(NId);
    453     OptimallyReducibleNodes.insert(NId);
    454     G.getNodeMetadata(NId).setReductionState(
    455       NodeMetadata::OptimallyReducible);
    456   }
    457 
    458   void moveToConservativelyAllocatableNodes(NodeId NId) {
    459     removeFromCurrentSet(NId);
    460     ConservativelyAllocatableNodes.insert(NId);
    461     G.getNodeMetadata(NId).setReductionState(
    462       NodeMetadata::ConservativelyAllocatable);
    463   }
    464 
    465   void moveToNotProvablyAllocatableNodes(NodeId NId) {
    466     removeFromCurrentSet(NId);
    467     NotProvablyAllocatableNodes.insert(NId);
    468     G.getNodeMetadata(NId).setReductionState(
    469       NodeMetadata::NotProvablyAllocatable);
    470   }
    471 
    472   void setup() {
    473     // Set up worklists.
    474     for (auto NId : G.nodeIds()) {
    475       if (G.getNodeDegree(NId) < 3)
    476         moveToOptimallyReducibleNodes(NId);
    477       else if (G.getNodeMetadata(NId).isConservativelyAllocatable())
    478         moveToConservativelyAllocatableNodes(NId);
    479       else
    480         moveToNotProvablyAllocatableNodes(NId);
    481     }
    482   }
    483 
    484   // Compute a reduction order for the graph by iteratively applying PBQP
    485   // reduction rules. Locally optimal rules are applied whenever possible (R0,
    486   // R1, R2). If no locally-optimal rules apply then any conservatively
    487   // allocatable node is reduced. Finally, if no conservatively allocatable
    488   // node exists then the node with the lowest spill-cost:degree ratio is
    489   // selected.
    490   std::vector<GraphBase::NodeId> reduce() {
    491     assert(!G.empty() && "Cannot reduce empty graph.");
    492 
    493     typedef GraphBase::NodeId NodeId;
    494     std::vector<NodeId> NodeStack;
    495 
    496     // Consume worklists.
    497     while (true) {
    498       if (!OptimallyReducibleNodes.empty()) {
    499         NodeSet::iterator NItr = OptimallyReducibleNodes.begin();
    500         NodeId NId = *NItr;
    501         OptimallyReducibleNodes.erase(NItr);
    502         NodeStack.push_back(NId);
    503         switch (G.getNodeDegree(NId)) {
    504         case 0:
    505           break;
    506         case 1:
    507           applyR1(G, NId);
    508           break;
    509         case 2:
    510           applyR2(G, NId);
    511           break;
    512         default: llvm_unreachable("Not an optimally reducible node.");
    513         }
    514       } else if (!ConservativelyAllocatableNodes.empty()) {
    515         // Conservatively allocatable nodes will never spill. For now just
    516         // take the first node in the set and push it on the stack. When we
    517         // start optimizing more heavily for register preferencing, it may
    518         // would be better to push nodes with lower 'expected' or worst-case
    519         // register costs first (since early nodes are the most
    520         // constrained).
    521         NodeSet::iterator NItr = ConservativelyAllocatableNodes.begin();
    522         NodeId NId = *NItr;
    523         ConservativelyAllocatableNodes.erase(NItr);
    524         NodeStack.push_back(NId);
    525         G.disconnectAllNeighborsFromNode(NId);
    526 
    527       } else if (!NotProvablyAllocatableNodes.empty()) {
    528         NodeSet::iterator NItr =
    529           std::min_element(NotProvablyAllocatableNodes.begin(),
    530                            NotProvablyAllocatableNodes.end(),
    531                            SpillCostComparator(G));
    532         NodeId NId = *NItr;
    533         NotProvablyAllocatableNodes.erase(NItr);
    534         NodeStack.push_back(NId);
    535         G.disconnectAllNeighborsFromNode(NId);
    536       } else
    537         break;
    538     }
    539 
    540     return NodeStack;
    541   }
    542 
    543   class SpillCostComparator {
    544   public:
    545     SpillCostComparator(const Graph& G) : G(G) {}
    546     bool operator()(NodeId N1Id, NodeId N2Id) {
    547       PBQPNum N1SC = G.getNodeCosts(N1Id)[0];
    548       PBQPNum N2SC = G.getNodeCosts(N2Id)[0];
    549       if (N1SC == N2SC)
    550         return G.getNodeDegree(N1Id) < G.getNodeDegree(N2Id);
    551       return N1SC < N2SC;
    552     }
    553   private:
    554     const Graph& G;
    555   };
    556 
    557   Graph& G;
    558   typedef std::set<NodeId> NodeSet;
    559   NodeSet OptimallyReducibleNodes;
    560   NodeSet ConservativelyAllocatableNodes;
    561   NodeSet NotProvablyAllocatableNodes;
    562 };
    563 
    564 class PBQPRAGraph : public PBQP::Graph<RegAllocSolverImpl> {
    565 private:
    566   typedef PBQP::Graph<RegAllocSolverImpl> BaseT;
    567 public:
    568   PBQPRAGraph(GraphMetadata Metadata) : BaseT(Metadata) {}
    569 
    570   /// @brief Dump this graph to dbgs().
    571   void dump() const;
    572 
    573   /// @brief Dump this graph to an output stream.
    574   /// @param OS Output stream to print on.
    575   void dump(raw_ostream &OS) const;
    576 
    577   /// @brief Print a representation of this graph in DOT format.
    578   /// @param OS Output stream to print on.
    579   void printDot(raw_ostream &OS) const;
    580 };
    581 
    582 inline Solution solve(PBQPRAGraph& G) {
    583   if (G.empty())
    584     return Solution();
    585   RegAllocSolverImpl RegAllocSolver(G);
    586   return RegAllocSolver.solve();
    587 }
    588 
    589 } // namespace RegAlloc
    590 } // namespace PBQP
    591 
    592 /// @brief Create a PBQP register allocator instance.
    593 FunctionPass *
    594 createPBQPRegisterAllocator(char *customPassID = nullptr);
    595 
    596 } // namespace llvm
    597 
    598 #endif /* LLVM_CODEGEN_REGALLOCPBQP_H */
    599