X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=blobdiff_plain;f=include%2Fllvm%2FCodeGen%2FRegAllocPBQP.h;h=3d242f1bebe1549f0e80809fc7aef976e856041e;hp=4b0e0bd6ff6f55fffb4f8ab1f8f17dee71f1041d;hb=96fc0d298c2ae67f8d68de6ffcf068f2c7162346;hpb=f4ccd110750a3f3fe6a107d5c74c649c2a0dc407

diff --git a/include/llvm/CodeGen/RegAllocPBQP.h b/include/llvm/CodeGen/RegAllocPBQP.h
index 4b0e0bd6ff6..3d242f1bebe 100644
--- a/include/llvm/CodeGen/RegAllocPBQP.h
+++ b/include/llvm/CodeGen/RegAllocPBQP.h
@@ -16,150 +16,394 @@
 #ifndef LLVM_CODEGEN_REGALLOCPBQP_H
 #define LLVM_CODEGEN_REGALLOCPBQP_H
 
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/SmallVector.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
-#include "llvm/CodeGen/PBQP/RegAllocSolver.h"
-#include <map>
-#include <set>
+#include "llvm/CodeGen/PBQPRAConstraint.h"
+#include "llvm/CodeGen/PBQP/CostAllocator.h"
+#include "llvm/CodeGen/PBQP/ReductionRules.h"
+#include "llvm/Support/ErrorHandling.h"
 
 namespace llvm {
-
-  class LiveIntervals;
-  class MachineBlockFrequencyInfo;
-  class MachineFunction;
-  class TargetRegisterInfo;
-
-  typedef PBQP::RegAlloc::Graph PBQPRAGraph;
-
-  /// This class wraps up a PBQP instance representing a register allocation
-  /// problem, plus the structures necessary to map back from the PBQP solution
-  /// to a register allocation solution. (i.e. The PBQP-node <--> vreg map,
-  /// and the PBQP option <--> storage location map).
-  class PBQPRAProblem {
+namespace PBQP {
+namespace RegAlloc {
+
+/// @brief Spill option index.
+inline unsigned getSpillOptionIdx() { return 0; }
+
+/// \brief Metadata to speed allocatability test.
+///
+/// Keeps track of the number of infinities in each row and column.
+class MatrixMetadata {
+private:
+  MatrixMetadata(const MatrixMetadata&);
+  void operator=(const MatrixMetadata&);
+public:
+  MatrixMetadata(const Matrix& M)
+    : WorstRow(0), WorstCol(0),
+      UnsafeRows(new bool[M.getRows() - 1]()),
+      UnsafeCols(new bool[M.getCols() - 1]()) {
+
+    unsigned* ColCounts = new unsigned[M.getCols() - 1]();
+
+    for (unsigned i = 1; i < M.getRows(); ++i) {
+      unsigned RowCount = 0;
+      for (unsigned j = 1; j < M.getCols(); ++j) {
+        if (M[i][j] == std::numeric_limits<PBQPNum>::infinity()) {
+          ++RowCount;
+          ++ColCounts[j - 1];
+          UnsafeRows[i - 1] = true;
+          UnsafeCols[j - 1] = true;
+        }
+      }
+      WorstRow = std::max(WorstRow, RowCount);
+    }
+    unsigned WorstColCountForCurRow =
+      *std::max_element(ColCounts, ColCounts + M.getCols() - 1);
+    WorstCol = std::max(WorstCol, WorstColCountForCurRow);
+    delete[] ColCounts;
+  }
+
+  ~MatrixMetadata() {
+    delete[] UnsafeRows;
+    delete[] UnsafeCols;
+  }
+
+  unsigned getWorstRow() const { return WorstRow; }
+  unsigned getWorstCol() const { return WorstCol; }
+  const bool* getUnsafeRows() const { return UnsafeRows; }
+  const bool* getUnsafeCols() const { return UnsafeCols; }
+
+private:
+  unsigned WorstRow, WorstCol;
+  bool* UnsafeRows;
+  bool* UnsafeCols;
+};
+
+class NodeMetadata {
+public:
+  typedef std::vector<unsigned> OptionToRegMap;
+
+  typedef enum { Unprocessed,
+                 OptimallyReducible,
+                 ConservativelyAllocatable,
+                 NotProvablyAllocatable } ReductionState;
+
+  NodeMetadata() : RS(Unprocessed), DeniedOpts(0), OptUnsafeEdges(nullptr){}
+  ~NodeMetadata() { delete[] OptUnsafeEdges; }
+
+  void setVReg(unsigned VReg) { this->VReg = VReg; }
+  unsigned getVReg() const { return VReg; }
+
+  void setOptionRegs(OptionToRegMap OptionRegs) {
+    this->OptionRegs = std::move(OptionRegs);
+  }
+  const OptionToRegMap& getOptionRegs() const { return OptionRegs; }
+
+  void setup(const Vector& Costs) {
+    NumOpts = Costs.getLength() - 1;
+    OptUnsafeEdges = new unsigned[NumOpts]();
+  }
+
+  ReductionState getReductionState() const { return RS; }
+  void setReductionState(ReductionState RS) { this->RS = RS; }
+
+  void handleAddEdge(const MatrixMetadata& MD, bool Transpose) {
+    DeniedOpts += Transpose ? MD.getWorstCol() : MD.getWorstRow();
+    const bool* UnsafeOpts =
+      Transpose ? MD.getUnsafeCols() : MD.getUnsafeRows();
+    for (unsigned i = 0; i < NumOpts; ++i)
+      OptUnsafeEdges[i] += UnsafeOpts[i];
+  }
+
+  void handleRemoveEdge(const MatrixMetadata& MD, bool Transpose) {
+    DeniedOpts -= Transpose ? MD.getWorstCol() : MD.getWorstRow();
+    const bool* UnsafeOpts =
+      Transpose ? MD.getUnsafeCols() : MD.getUnsafeRows();
+    for (unsigned i = 0; i < NumOpts; ++i)
+      OptUnsafeEdges[i] -= UnsafeOpts[i];
+  }
+
+  bool isConservativelyAllocatable() const {
+    return (DeniedOpts < NumOpts) ||
+      (std::find(OptUnsafeEdges, OptUnsafeEdges + NumOpts, 0) !=
+       OptUnsafeEdges + NumOpts);
+  }
+
+private:
+  ReductionState RS;
+  unsigned NumOpts;
+  unsigned DeniedOpts;
+  unsigned* OptUnsafeEdges;
+  unsigned VReg;
+  OptionToRegMap OptionRegs;
+};
+
+class RegAllocSolverImpl {
+private:
+  typedef MDMatrix<MatrixMetadata> RAMatrix;
+public:
+  typedef PBQP::Vector RawVector;
+  typedef PBQP::Matrix RawMatrix;
+  typedef PBQP::Vector Vector;
+  typedef RAMatrix     Matrix;
+  typedef PBQP::PoolCostAllocator<Vector, Matrix> CostAllocator;
+
+  typedef GraphBase::NodeId NodeId;
+  typedef GraphBase::EdgeId EdgeId;
+
+  typedef RegAlloc::NodeMetadata NodeMetadata;
+
+  struct EdgeMetadata { };
+
+  class GraphMetadata {
   public:
+    GraphMetadata(MachineFunction &MF,
+                  LiveIntervals &LIS,
+                  MachineBlockFrequencyInfo &MBFI)
+      : MF(MF), LIS(LIS), MBFI(MBFI) {}
 
-    typedef SmallVector<unsigned, 16> AllowedSet;
-
-    PBQPRAGraph& getGraph() { return graph; }
+    MachineFunction &MF;
+    LiveIntervals &LIS;
+    MachineBlockFrequencyInfo &MBFI;
 
-    const PBQPRAGraph& getGraph() const { return graph; }
-
-    /// Record the mapping between the given virtual register and PBQP node,
-    /// and the set of allowed pregs for the vreg.
-    ///
-    /// If you are extending
-    /// PBQPBuilder you are unlikely to need this: Nodes and options for all
-    /// vregs will already have been set up for you by the base class.
-    template <typename AllowedRegsItr>
-    void recordVReg(unsigned vreg, PBQPRAGraph::NodeId nodeId,
-                    AllowedRegsItr arBegin, AllowedRegsItr arEnd) {
-      assert(node2VReg.find(nodeId) == node2VReg.end() && "Re-mapping node.");
-      assert(vreg2Node.find(vreg) == vreg2Node.end() && "Re-mapping vreg.");
-      assert(allowedSets[vreg].empty() && "vreg already has pregs.");
-
-      node2VReg[nodeId] = vreg;
-      vreg2Node[vreg] = nodeId;
-      std::copy(arBegin, arEnd, std::back_inserter(allowedSets[vreg]));
+    void setNodeIdForVReg(unsigned VReg, GraphBase::NodeId NId) {
+      VRegToNodeId[VReg] = NId;
     }
 
-    /// Get the virtual register corresponding to the given PBQP node.
-    unsigned getVRegForNode(PBQPRAGraph::NodeId nodeId) const;
-
-    /// Get the PBQP node corresponding to the given virtual register.
-    PBQPRAGraph::NodeId getNodeForVReg(unsigned vreg) const;
-
-    /// Returns true if the given PBQP option represents a physical register,
-    /// false otherwise.
-    bool isPRegOption(unsigned vreg, unsigned option) const {
-      // At present we only have spills or pregs, so anything that's not a
-      // spill is a preg. (This might be extended one day to support remat).
-      return !isSpillOption(vreg, option);
+    GraphBase::NodeId getNodeIdForVReg(unsigned VReg) const {
+      auto VRegItr = VRegToNodeId.find(VReg);
+      if (VRegItr == VRegToNodeId.end())
+        return GraphBase::invalidNodeId();
+      return VRegItr->second;
     }
 
-    /// Returns true if the given PBQP option represents spilling, false
-    /// otherwise.
-    bool isSpillOption(unsigned vreg, unsigned option) const {
-      // We hardcode option zero as the spill option.
-      return option == 0;
+    void eraseNodeIdForVReg(unsigned VReg) {
+      VRegToNodeId.erase(VReg);
     }
 
-    /// Returns the allowed set for the given virtual register.
-    const AllowedSet& getAllowedSet(unsigned vreg) const;
-
-    /// Get PReg for option.
-    unsigned getPRegForOption(unsigned vreg, unsigned option) const;
-
   private:
-
-    typedef std::map<PBQPRAGraph::NodeId, unsigned>  Node2VReg;
-    typedef DenseMap<unsigned, PBQPRAGraph::NodeId> VReg2Node;
-    typedef DenseMap<unsigned, AllowedSet> AllowedSetMap;
-
-    PBQPRAGraph graph;
-    Node2VReg node2VReg;
-    VReg2Node vreg2Node;
-
-    AllowedSetMap allowedSets;
-
+    DenseMap<unsigned, NodeId> VRegToNodeId;
   };
 
-  /// Builds PBQP instances to represent register allocation problems. Includes
-  /// spill, interference and coalescing costs by default. You can extend this
-  /// class to support additional constraints for your architecture.
-  class PBQPBuilder {
-  private:
-    PBQPBuilder(const PBQPBuilder&) LLVM_DELETED_FUNCTION;
-    void operator=(const PBQPBuilder&) LLVM_DELETED_FUNCTION;
-  public:
-
-    typedef std::set<unsigned> RegSet;
-
-    /// Default constructor.
-    PBQPBuilder() {}
+  typedef PBQP::Graph<RegAllocSolverImpl> Graph;
+
+  RegAllocSolverImpl(Graph &G) : G(G) {}
+
+  Solution solve() {
+    G.setSolver(*this);
+    Solution S;
+    setup();
+    S = backpropagate(G, reduce());
+    G.unsetSolver();
+    return S;
+  }
+
+  void handleAddNode(NodeId NId) {
+    G.getNodeMetadata(NId).setup(G.getNodeCosts(NId));
+  }
+  void handleRemoveNode(NodeId NId) {}
+  void handleSetNodeCosts(NodeId NId, const Vector& newCosts) {}
+
+  void handleAddEdge(EdgeId EId) {
+    handleReconnectEdge(EId, G.getEdgeNode1Id(EId));
+    handleReconnectEdge(EId, G.getEdgeNode2Id(EId));
+  }
+
+  void handleRemoveEdge(EdgeId EId) {
+    handleDisconnectEdge(EId, G.getEdgeNode1Id(EId));
+    handleDisconnectEdge(EId, G.getEdgeNode2Id(EId));
+  }
+
+  void handleDisconnectEdge(EdgeId EId, NodeId NId) {
+    NodeMetadata& NMd = G.getNodeMetadata(NId);
+    const MatrixMetadata& MMd = G.getEdgeCosts(EId).getMetadata();
+    NMd.handleRemoveEdge(MMd, NId == G.getEdgeNode2Id(EId));
+    if (G.getNodeDegree(NId) == 3) {
+      // This node is becoming optimally reducible.
+      moveToOptimallyReducibleNodes(NId);
+    } else if (NMd.getReductionState() ==
+               NodeMetadata::NotProvablyAllocatable &&
+               NMd.isConservativelyAllocatable()) {
+      // This node just became conservatively allocatable.
+      moveToConservativelyAllocatableNodes(NId);
+    }
+  }
+
+  void handleReconnectEdge(EdgeId EId, NodeId NId) {
+    NodeMetadata& NMd = G.getNodeMetadata(NId);
+    const MatrixMetadata& MMd = G.getEdgeCosts(EId).getMetadata();
+    NMd.handleAddEdge(MMd, NId == G.getEdgeNode2Id(EId));
+  }
+
+  void handleSetEdgeCosts(EdgeId EId, const Matrix& NewCosts) {
+    handleRemoveEdge(EId);
+
+    NodeId N1Id = G.getEdgeNode1Id(EId);
+    NodeId N2Id = G.getEdgeNode2Id(EId);
+    NodeMetadata& N1Md = G.getNodeMetadata(N1Id);
+    NodeMetadata& N2Md = G.getNodeMetadata(N2Id);
+    const MatrixMetadata& MMd = NewCosts.getMetadata();
+    N1Md.handleAddEdge(MMd, N1Id != G.getEdgeNode1Id(EId));
+    N2Md.handleAddEdge(MMd, N2Id != G.getEdgeNode1Id(EId));
+  }
+
+private:
+
+  void removeFromCurrentSet(NodeId NId) {
+    switch (G.getNodeMetadata(NId).getReductionState()) {
+    case NodeMetadata::Unprocessed: break;
+    case NodeMetadata::OptimallyReducible:
+      assert(OptimallyReducibleNodes.find(NId) !=
+             OptimallyReducibleNodes.end() &&
+             "Node not in optimally reducible set.");
+      OptimallyReducibleNodes.erase(NId);
+      break;
+    case NodeMetadata::ConservativelyAllocatable:
+      assert(ConservativelyAllocatableNodes.find(NId) !=
+             ConservativelyAllocatableNodes.end() &&
+             "Node not in conservatively allocatable set.");
+      ConservativelyAllocatableNodes.erase(NId);
+      break;
+    case NodeMetadata::NotProvablyAllocatable:
+      assert(NotProvablyAllocatableNodes.find(NId) !=
+             NotProvablyAllocatableNodes.end() &&
+             "Node not in not-provably-allocatable set.");
+      NotProvablyAllocatableNodes.erase(NId);
+      break;
+    }
+  }
+
+  void moveToOptimallyReducibleNodes(NodeId NId) {
+    removeFromCurrentSet(NId);
+    OptimallyReducibleNodes.insert(NId);
+    G.getNodeMetadata(NId).setReductionState(
+      NodeMetadata::OptimallyReducible);
+  }
+
+  void moveToConservativelyAllocatableNodes(NodeId NId) {
+    removeFromCurrentSet(NId);
+    ConservativelyAllocatableNodes.insert(NId);
+    G.getNodeMetadata(NId).setReductionState(
+      NodeMetadata::ConservativelyAllocatable);
+  }
+
+  void moveToNotProvablyAllocatableNodes(NodeId NId) {
+    removeFromCurrentSet(NId);
+    NotProvablyAllocatableNodes.insert(NId);
+    G.getNodeMetadata(NId).setReductionState(
+      NodeMetadata::NotProvablyAllocatable);
+  }
+
+  void setup() {
+    // Set up worklists.
+    for (auto NId : G.nodeIds()) {
+      if (G.getNodeDegree(NId) < 3)
+        moveToOptimallyReducibleNodes(NId);
+      else if (G.getNodeMetadata(NId).isConservativelyAllocatable())
+        moveToConservativelyAllocatableNodes(NId);
+      else
+        moveToNotProvablyAllocatableNodes(NId);
+    }
+  }
+
+  // Compute a reduction order for the graph by iteratively applying PBQP
+  // reduction rules. Locally optimal rules are applied whenever possible (R0,
+  // R1, R2). If no locally-optimal rules apply then any conservatively
+  // allocatable node is reduced. Finally, if no conservatively allocatable
+  // node exists then the node with the lowest spill-cost:degree ratio is
+  // selected.
+  std::vector<GraphBase::NodeId> reduce() {
+    assert(!G.empty() && "Cannot reduce empty graph.");
+
+    typedef GraphBase::NodeId NodeId;
+    std::vector<NodeId> NodeStack;
+
+    // Consume worklists.
+    while (true) {
+      if (!OptimallyReducibleNodes.empty()) {
+        NodeSet::iterator NItr = OptimallyReducibleNodes.begin();
+        NodeId NId = *NItr;
+        OptimallyReducibleNodes.erase(NItr);
+        NodeStack.push_back(NId);
+        switch (G.getNodeDegree(NId)) {
+        case 0:
+          break;
+        case 1:
+          applyR1(G, NId);
+          break;
+        case 2:
+          applyR2(G, NId);
+          break;
+        default: llvm_unreachable("Not an optimally reducible node.");
+        }
+      } else if (!ConservativelyAllocatableNodes.empty()) {
+        // Conservatively allocatable nodes will never spill. For now just
+        // take the first node in the set and push it on the stack. When we
+        // start optimizing more heavily for register preferencing, it may
+        // would be better to push nodes with lower 'expected' or worst-case
+        // register costs first (since early nodes are the most
+        // constrained).
+        NodeSet::iterator NItr = ConservativelyAllocatableNodes.begin();
+        NodeId NId = *NItr;
+        ConservativelyAllocatableNodes.erase(NItr);
+        NodeStack.push_back(NId);
+        G.disconnectAllNeighborsFromNode(NId);
+
+      } else if (!NotProvablyAllocatableNodes.empty()) {
+        NodeSet::iterator NItr =
+          std::min_element(NotProvablyAllocatableNodes.begin(),
+                           NotProvablyAllocatableNodes.end(),
+                           SpillCostComparator(G));
+        NodeId NId = *NItr;
+        NotProvablyAllocatableNodes.erase(NItr);
+        NodeStack.push_back(NId);
+        G.disconnectAllNeighborsFromNode(NId);
+      } else
+        break;
+    }
 
-    /// Clean up a PBQPBuilder.
-    virtual ~PBQPBuilder() {}
+    return NodeStack;
+  }
 
-    /// Build a PBQP instance to represent the register allocation problem for
-    /// the given MachineFunction.
-    virtual PBQPRAProblem *build(MachineFunction *mf, const LiveIntervals *lis,
-                                 const MachineBlockFrequencyInfo *mbfi,
-                                 const RegSet &vregs);
+  class SpillCostComparator {
+  public:
+    SpillCostComparator(const Graph& G) : G(G) {}
+    bool operator()(NodeId N1Id, NodeId N2Id) {
+      PBQPNum N1SC = G.getNodeCosts(N1Id)[0] / G.getNodeDegree(N1Id);
+      PBQPNum N2SC = G.getNodeCosts(N2Id)[0] / G.getNodeDegree(N2Id);
+      return N1SC < N2SC;
+    }
   private:
-
-    void addSpillCosts(PBQP::Vector &costVec, PBQP::PBQPNum spillCost);
-
-    void addInterferenceCosts(PBQP::Matrix &costMat,
-                              const PBQPRAProblem::AllowedSet &vr1Allowed,
-                              const PBQPRAProblem::AllowedSet &vr2Allowed,
-                              const TargetRegisterInfo *tri);
+    const Graph& G;
   };
 
-  /// Extended builder which adds coalescing constraints to a problem.
-  class PBQPBuilderWithCoalescing : public PBQPBuilder {
-  public:
-
-    /// Build a PBQP instance to represent the register allocation problem for
-    /// the given MachineFunction.
-    virtual PBQPRAProblem *build(MachineFunction *mf, const LiveIntervals *lis,
-                                 const MachineBlockFrequencyInfo *mbfi,
-                                 const RegSet &vregs);
-
-  private:
+  Graph& G;
+  typedef std::set<NodeId> NodeSet;
+  NodeSet OptimallyReducibleNodes;
+  NodeSet ConservativelyAllocatableNodes;
+  NodeSet NotProvablyAllocatableNodes;
+};
+
+class PBQPRAGraph : public PBQP::Graph<RegAllocSolverImpl> {
+private:
+  typedef PBQP::Graph<RegAllocSolverImpl> BaseT;
+public:
+  PBQPRAGraph(GraphMetadata Metadata) : BaseT(Metadata) {}
+};
+
+inline Solution solve(PBQPRAGraph& G) {
+  if (G.empty())
+    return Solution();
+  RegAllocSolverImpl RegAllocSolver(G);
+  return RegAllocSolver.solve();
+}
 
-    void addPhysRegCoalesce(PBQP::Vector &costVec, unsigned pregOption,
-                            PBQP::PBQPNum benefit);
+} // namespace RegAlloc
+} // namespace PBQP
 
-    void addVirtRegCoalesce(PBQP::Matrix &costMat,
-                            const PBQPRAProblem::AllowedSet &vr1Allowed,
-                            const PBQPRAProblem::AllowedSet &vr2Allowed,
-                            PBQP::PBQPNum benefit);
-  };
+/// @brief Create a PBQP register allocator instance.
+FunctionPass *
+createPBQPRegisterAllocator(char *customPassID = nullptr);
 
-  FunctionPass *
-  createPBQPRegisterAllocator(std::unique_ptr<PBQPBuilder> &builder,
-                              char *customPassID = 0);
-}
+} // namespace llvm
 
 #endif /* LLVM_CODEGEN_REGALLOCPBQP_H */