LoopUnswitching.hpp

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/*
 * Copyright 2017 Nico Reißmann <nico.reissmann@gmail.com>
 * See COPYING for terms of redistribution.
 */
 
#ifndef JLM_LLVM_OPT_LOOPUNSWITCHING_HPP
#define JLM_LLVM_OPT_LOOPUNSWITCHING_HPP
 
#include <jlm/rvsdg/Transformation.hpp>
 
namespace jlm::rvsdg
{
class GammaNode;
class Node;
class Region;
class SubstitutionMap;
class ThetaNode;
}
 
namespace jlm::llvm
{
 
class ThetaGammaPredicateCorrelation;
 
class LoopUnswitchingHeuristic
{
public:
  virtual ~LoopUnswitchingHeuristic() noexcept;
 
  virtual bool
  shouldUnswitchLoop(ThetaGammaPredicateCorrelation & correlation) const noexcept = 0;
};
 
class LoopUnswitchingDefaultHeuristic final : public LoopUnswitchingHeuristic
{
public:
  ~LoopUnswitchingDefaultHeuristic() noexcept override;
 
  bool
  shouldUnswitchLoop(ThetaGammaPredicateCorrelation & correlation) const noexcept override;
 
  static std::shared_ptr<const LoopUnswitchingDefaultHeuristic>
  create();
};
 
class LoopUnswitching final : public rvsdg::Transformation
{
public:
  class Statistics;
 
  ~LoopUnswitching() noexcept override;
 
  explicit LoopUnswitching(std::shared_ptr<const LoopUnswitchingHeuristic> heuristic)
      : Transformation("LoopUnswitching"),
        heuristic_(std::move(heuristic))
  {}
 
  void
  Run(rvsdg::RvsdgModule & rvsdgModule, util::StatisticsCollector & statisticsCollector) override;
 
  static void
  CreateAndRun(
      rvsdg::RvsdgModule & rvsdgModule,
      util::StatisticsCollector & statisticsCollector,
      std::shared_ptr<const LoopUnswitchingHeuristic> heuristic);
 
private:
  void
  HandleRegion(rvsdg::Region & region);
 
  bool
  UnswitchLoop(rvsdg::ThetaNode & thetaNode);
 
  static rvsdg::GammaNode *
  IsUnswitchable(const rvsdg::ThetaNode & thetaNode);
 
  static void
  SinkNodesIntoGamma(rvsdg::GammaNode & gammaNode, const rvsdg::ThetaNode & thetaNode);
 
  static std::vector<std::vector<rvsdg::Node *>>
  CollectPredicateNodes(const rvsdg::ThetaNode & thetaNode, const rvsdg::GammaNode & gammaNode);
 
  static void
  CopyPredicateNodes(
      rvsdg::Region & target,
      rvsdg::SubstitutionMap & substitutionMap,
      const std::vector<std::vector<rvsdg::Node *>> & nodes);
 
  static bool
  allLoopVarsAreRoutedThroughGamma(
      const rvsdg::ThetaNode & thetaNode,
      const rvsdg::GammaNode & gammaNode);
 
  std::shared_ptr<const LoopUnswitchingHeuristic> heuristic_;
};
 
}
 
#endif