src/IceCfgNode.h

//===- subzero/src/IceCfgNode.h - Control flow graph node -------*- C++ -*-===//
//
//                        The Subzero Code Generator
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file declares the CfgNode class, which represents a single
/// basic block as its instruction list, in-edge list, and out-edge
/// list.
///
//===----------------------------------------------------------------------===//

#ifndef SUBZERO_SRC_ICECFGNODE_H
#define SUBZERO_SRC_ICECFGNODE_H

#include "IceDefs.h"
#include "IceInst.h" // InstList traits

namespace Ice {

class CfgNode {
  CfgNode() = delete;
  CfgNode(const CfgNode &) = delete;
  CfgNode &operator=(const CfgNode &) = delete;

public:
  static CfgNode *create(Cfg *Func, SizeT LabelIndex) {
    return new (Func->allocate<CfgNode>()) CfgNode(Func, LabelIndex);
  }

  /// Access the label number and name for this node.
  SizeT getIndex() const { return Number; }
  void resetIndex(SizeT NewNumber) { Number = NewNumber; }
  IceString getName() const;
  void setName(const IceString &NewName) {
    // Make sure that the name can only be set once.
    assert(NameIndex == Cfg::IdentifierIndexInvalid);
    if (!NewName.empty())
      NameIndex = Func->addIdentifierName(NewName);
  }
  IceString getAsmName() const {
    return ".L" + Func->getFunctionName() + "$" + getName();
  }

  /// The HasReturn flag indicates that this node contains a return
  /// instruction and therefore needs an epilog.
  void setHasReturn() { HasReturn = true; }
  bool getHasReturn() const { return HasReturn; }

  void setNeedsPlacement(bool Value) { NeedsPlacement = Value; }
  bool needsPlacement() const { return NeedsPlacement; }

  /// \name Access predecessor and successor edge lists.
  /// @{
  const NodeList &getInEdges() const { return InEdges; }
  const NodeList &getOutEdges() const { return OutEdges; }
  /// @}

  /// \name Manage the instruction list.
  /// @{
  InstList &getInsts() { return Insts; }
  PhiList &getPhis() { return Phis; }
  void appendInst(Inst *Inst);
  void renumberInstructions();
  /// Rough and generally conservative estimate of the number of
  /// instructions in the block.  It is updated when an instruction is
  /// added, but not when deleted.  It is recomputed during
  /// renumberInstructions().
  InstNumberT getInstCountEstimate() const { return InstCountEstimate; }
  /// @}

  /// \name Manage predecessors and successors.
  /// @{

  /// Add a predecessor edge to the InEdges list for each of this
  /// node's successors.
  void computePredecessors();
  void computeSuccessors();
  CfgNode *splitIncomingEdge(CfgNode *Pred, SizeT InEdgeIndex);
  /// @}

  void placePhiLoads();
  void placePhiStores();
  void deletePhis();
  void advancedPhiLowering();
  void doAddressOpt();
  void doNopInsertion();
  void genCode();
  void livenessLightweight();
  bool liveness(Liveness *Liveness);
  void livenessAddIntervals(Liveness *Liveness, InstNumberT FirstInstNum,
                            InstNumberT LastInstNum);
  void contractIfEmpty();
  void doBranchOpt(const CfgNode *NextNode);
  void emit(Cfg *Func) const;
  void emitIAS(Cfg *Func) const;
  void dump(Cfg *Func) const;

  void profileExecutionCount(VariableDeclaration *Var);

private:
  CfgNode(Cfg *Func, SizeT LabelIndex);
  Cfg *const Func;
  SizeT Number; /// label index
  Cfg::IdentifierIndexType NameIndex =
      Cfg::IdentifierIndexInvalid; /// index into Cfg::NodeNames table
  bool HasReturn = false;          /// does this block need an epilog?
  bool NeedsPlacement = false;
  InstNumberT InstCountEstimate = 0; /// rough instruction count estimate
  NodeList InEdges;                  /// in no particular order
  NodeList OutEdges;                 /// in no particular order
  PhiList Phis;                      /// unordered set of phi instructions
  InstList Insts;                    /// ordered list of non-phi instructions
};

} // end of namespace Ice

#endif // SUBZERO_SRC_ICECFGNODE_H