//===-- Analysis.h  - Swift Analysis ----------------------------*- C++ -*-===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2015 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See http://swift.org/LICENSE.txt for license information
// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

#include "llvm/Support/Casting.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/SmallVector.h"
#include <vector>

#ifndef SWIFT_SILANALYSIS_ANALYSIS_H
#define SWIFT_SILANALYSIS_ANALYSIS_H

namespace swift {
  class SILModule;
  class SILFunction;
  class SILPassManager;

  /// The base class for all SIL-level analysis.
  class SILAnalysis {
  public:
    /// This is a list of values that allow passes to communicate to analysis
    /// which traits of the code were preserved. Based on this information
    /// the analysis can decide if it needs to be invalidated. This information
    /// may refer to a specific function or to a list of functions depending
    /// on the context in which it is used.
    enum PreserveKind : unsigned {
      Nothing     = 0x0,   // The pass does not preserve any analysis trait.
      Calls       = 0x1,   // The pass did not modify any calls.
      Branches    = 0x2,   // The pass did not modify any branches.

      // This is a list of combined traits that is defined to make the use of
      /// the invalidation API more convenient.
      ProgramFlow = Calls | Branches, // The pass changed some instructions but
                                   // did not change the overall flow
                                   // of the code.
    };

    /// A list of the known analysis.
    enum class AnalysisKind {
      CompleteFuncs,
      CallGraph,
      Dominance,
      PostDominance,
      Alias,
      LoopInfo,
      IVAnalysis,
      PostOrder,
      ClassHierarchyAnalysis,
      RCIdentity,
      Destructor
    };

  private:
    /// Stores the kind of derived class.
    const AnalysisKind Kind;

    /// A lock that prevents the invalidation of this analysis. When this
    /// variable is set to True then the PassManager should not invalidate
    /// this analysis.
    bool invalidationLock;

  public:

    /// Returns the kind of derived class.
    AnalysisKind getKind() const { return Kind; }

    /// C'tor.
    SILAnalysis(AnalysisKind K) : Kind(K), invalidationLock(false) {}

    /// D'tor.
    virtual ~SILAnalysis() {}

    /// Lock the analysis. This means that invalidation messages are ignored.
    void lockInvalidation() {invalidationLock = true; }

    /// Unlock the analysis. This means that invalidation messages are handled.
    void unlockInvalidation() {invalidationLock = false; }

    /// Return True if this analysis is locked and should not be invalidated.
    bool isLocked() { return invalidationLock; }

    /// Invalidate all information in this analysis.
    virtual void invalidate(PreserveKind K) {}

    /// Invalidate all of the information for a specific function.
    virtual void invalidate(SILFunction *F, PreserveKind K) {}

    /// Verify the state of this analysis.
    virtual void verify() const {}
  };

  /// An abstract base class that implements the boiler plate of cacheing and
  /// invalidating analysis for specific functions.
  template<typename AnalysisTy>
  class FunctionAnalysisBase : public SILAnalysis {
  protected:
    typedef llvm::DenseMap<SILFunction *, AnalysisTy *> StorageTy;

    /// Maps functions to their analysis provider.
    StorageTy Storage;

    /// Construct a new empty analysis for a specific function \p F.
    virtual AnalysisTy *newFunctionAnalysis(SILFunction *F) = 0;

    /// Return True if the analysis should be invalidated given trait \K is
    /// preserved.
    virtual bool shouldInvalidate(SILAnalysis::PreserveKind K) = 0;

  public:
    /// Returns an analysis provider for a specific function \p F.
    AnalysisTy *get(SILFunction *F) {
      auto &it = Storage.FindAndConstruct(F);
      if (!it.second)
        it.second = newFunctionAnalysis(F);
      return it.second;
    }

    virtual void invalidate(SILAnalysis::PreserveKind K) {
      if (!shouldInvalidate(K)) return;

      for (auto D : Storage)
        delete D.second;

      Storage.clear();
    }

    virtual void invalidate(SILFunction *F, SILAnalysis::PreserveKind K) {
      if (!shouldInvalidate(K)) return;

      auto &it = Storage.FindAndConstruct(F);
      if (it.second) {
        delete it.second;
        it.second = nullptr;
      }
    }

    FunctionAnalysisBase(AnalysisKind K) : SILAnalysis(K), Storage() {}
    FunctionAnalysisBase(const FunctionAnalysisBase &) = delete;
    FunctionAnalysisBase &operator=(const FunctionAnalysisBase &) = delete;
    FunctionAnalysisBase() {}
  };

  SILAnalysis *createCallGraphAnalysis(SILModule *M);
  SILAnalysis *createAliasAnalysis(SILModule *M);
  SILAnalysis *createDominanceAnalysis(SILModule *M);
  SILAnalysis *createPostDominanceAnalysis(SILModule *M);
  SILAnalysis *createLoopInfoAnalysis(SILModule *M, SILPassManager *PM);
  SILAnalysis *createInductionVariableAnalysis(SILModule *M);
  SILAnalysis *createPostOrderAnalysis(SILModule *M);
  SILAnalysis *createClassHierarchyAnalysis(SILModule *M);
  SILAnalysis *createRCIdentityAnalysis(SILModule *M, SILPassManager *PM);
  SILAnalysis *createDestructorAnalysis(SILModule *M);
} // end namespace swift

#endif