path: root/lib/VMCore/PassManager.cpp

//===- PassManager.cpp - LLVM Pass Infrastructure Implementation ----------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file was developed by Devang Patel and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the LLVM Pass Manager infrastructure. 
//
//===----------------------------------------------------------------------===//


#include "llvm/PassManager.h"
#include "llvm/Module.h"
#include "llvm/ModuleProvider.h"
#include "llvm/Support/Streams.h"
#include <vector>
#include <map>
using namespace llvm;

//===----------------------------------------------------------------------===//
// Overview:
// The Pass Manager Infrastructure manages passes. It's responsibilities are:
// 
//   o Manage optimization pass execution order
//   o Make required Analysis information available before pass P is run
//   o Release memory occupied by dead passes
//   o If Analysis information is dirtied by a pass then regenerate Analysis 
//     information before it is consumed by another pass.
//
// Pass Manager Infrastructure uses multipe pass managers. They are PassManager,
// FunctionPassManager, ModulePassManager, BasicBlockPassManager. This class 
// hierarcy uses multiple inheritance but pass managers do not derive from
// another pass manager.
//
// PassManager and FunctionPassManager are two top level pass manager that
// represents the external interface of this entire pass manager infrastucture.
//
// Important classes :
//
// [o] class PMTopLevelManager;
//
// Two top level managers, PassManager and FunctionPassManager, derive from 
// PMTopLevelManager. PMTopLevelManager manages information used by top level 
// managers such as last user info.
//
// [o] class PMDataManager;
//
// PMDataManager manages information, e.g. list of available analysis info, 
// used by a pass manager to manage execution order of passes. It also provides
// a place to implement common pass manager APIs. All pass managers derive from
// PMDataManager.
//
// [o] class BasicBlockPassManager : public FunctionPass, public PMDataManager;
//
// BasicBlockPassManager manages BasicBlockPasses.
//
// [o] class FunctionPassManager;
//
// This is a external interface used by JIT to manage FunctionPasses. This
// interface relies on FunctionPassManagerImpl to do all the tasks.
//
// [o] class FunctionPassManagerImpl : public ModulePass, PMDataManager,
//                                     public PMTopLevelManager;
//
// FunctionPassManagerImpl is a top level manager. It manages FunctionPasses
// and BasicBlockPassManagers.
//
// [o] class ModulePassManager : public Pass, public PMDataManager;
//
// ModulePassManager manages ModulePasses and FunctionPassManagerImpls.
//
// [o] class PassManager;
//
// This is a external interface used by various tools to manages passes. It
// relies on PassManagerImpl to do all the tasks.
//
// [o] class PassManagerImpl : public Pass, public PMDataManager,
//                             public PMDTopLevelManager
//
// PassManagerImpl is a top level pass manager responsible for managing
// ModulePassManagers.
//===----------------------------------------------------------------------===//

namespace llvm {

//===----------------------------------------------------------------------===//
// PMTopLevelManager
//
/// PMTopLevelManager manages LastUser info and collects common APIs used by
/// top level pass managers.
class PMTopLevelManager {

public:

  inline std::vector<Pass *>::iterator passManagersBegin() { 
    return PassManagers.begin(); 
  }

  inline std::vector<Pass *>::iterator passManagersEnd() { 
    return PassManagers.end();
  }

  /// Schedule pass P for execution. Make sure that passes required by
  /// P are run before P is run. Update analysis info maintained by
  /// the manager. Remove dead passes. This is a recursive function.
  void schedulePass(Pass *P);

  /// This is implemented by top level pass manager and used by 
  /// schedulePass() to add analysis info passes that are not available.
  virtual void addTopLevelPass(Pass  *P) = 0;

  /// Set pass P as the last user of the given analysis passes.
  void setLastUser(std::vector<Pass *> &AnalysisPasses, Pass *P);

  /// Collect passes whose last user is P
  void collectLastUses(std::vector<Pass *> &LastUses, Pass *P);

  /// Find the pass that implements Analysis AID. Search immutable
  /// passes and all pass managers. If desired pass is not found
  /// then return NULL.
  Pass *findAnalysisPass(AnalysisID AID);

  virtual ~PMTopLevelManager() {
    PassManagers.clear();
  }

  /// Add immutable pass and initialize it.
  inline void addImmutablePass(ImmutablePass *P) {
    P->initializePass();
    ImmutablePasses.push_back(P);
  }

  inline std::vector<ImmutablePass *>& getImmutablePasses() {
    return ImmutablePasses;
  }

  void addPassManager(Pass *Manager) {
    PassManagers.push_back(Manager);
  }

  // Add Manager into the list of managers that are not directly
  // maintained by this top level pass manager
  void addOtherPassManager(Pass *Manager) {
    OtherPassManagers.push_back(Manager);
  }

private:
  
  /// Collection of pass managers
  std::vector<Pass *> PassManagers;

  /// Collection of pass managers that are not directly maintained
  /// by this pass manager
  std::vector<Pass *> OtherPassManagers;

  // Map to keep track of last user of the analysis pass.
  // LastUser->second is the last user of Lastuser->first.
  std::map<Pass *, Pass *> LastUser;

  /// Immutable passes are managed by top level manager.
  std::vector<ImmutablePass *> ImmutablePasses;
};
  
/// Set pass P as the last user of the given analysis passes.
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