AnalysisContext.h

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//=== AnalysisContext.h - Analysis context for Path Sens analysis --*- C++ -*-//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines AnalysisDeclContext, a class that manages the analysis
// context data for path sensitive analysis.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_ANALYSIS_ANALYSISCONTEXT_H
#define LLVM_CLANG_ANALYSIS_ANALYSISCONTEXT_H

#include "clang/AST/Decl.h"
#include "clang/Analysis/CFG.h"
#include "clang/Analysis/CodeInjector.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/Support/Allocator.h"
#include <memory>

namespace clang {

class Stmt;
class CFGReverseBlockReachabilityAnalysis;
class CFGStmtMap;
class LiveVariables;
class ManagedAnalysis;
class ParentMap;
class PseudoConstantAnalysis;
class LocationContextManager;
class StackFrameContext;
class BlockInvocationContext;
class AnalysisDeclContextManager;
class LocationContext;

namespace idx { class TranslationUnit; }

/// The base class of a hierarchy of objects representing analyses tied
/// to AnalysisDeclContext.
class ManagedAnalysis {
protected:
  ManagedAnalysis() {}
public:
  virtual ~ManagedAnalysis();

  // Subclasses need to implement:
  //
  //  static const void *getTag();
  //
  // Which returns a fixed pointer address to distinguish classes of
  // analysis objects.  They also need to implement:
  //
  //  static [Derived*] create(AnalysisDeclContext &Ctx);
  //
  // which creates the analysis object given an AnalysisDeclContext.
};


/// AnalysisDeclContext contains the context data for the function or method
/// under analysis.
class AnalysisDeclContext {
  /// Backpoint to the AnalysisManager object that created this
  /// AnalysisDeclContext. This may be null.
  AnalysisDeclContextManager *Manager;

  const Decl * const D;

  std::unique_ptr<CFG> cfg, completeCFG;
  std::unique_ptr<CFGStmtMap> cfgStmtMap;

  CFG::BuildOptions cfgBuildOptions;
  CFG::BuildOptions::ForcedBlkExprs *forcedBlkExprs;

  bool builtCFG, builtCompleteCFG;
  std::unique_ptr<ParentMap> PM;
  std::unique_ptr<PseudoConstantAnalysis> PCA;
  std::unique_ptr<CFGReverseBlockReachabilityAnalysis> CFA;

  llvm::BumpPtrAllocator A;

  llvm::DenseMap<const BlockDecl*,void*> *ReferencedBlockVars;

  void *ManagedAnalyses;

public:
  AnalysisDeclContext(AnalysisDeclContextManager *Mgr,
                  const Decl *D);

  AnalysisDeclContext(AnalysisDeclContextManager *Mgr,
                  const Decl *D,
                  const CFG::BuildOptions &BuildOptions);

  ~AnalysisDeclContext();

  ASTContext &getASTContext() const { return D->getASTContext(); }
  const Decl *getDecl() const { return D; }

  /// Return the AnalysisDeclContextManager (if any) that created
  /// this AnalysisDeclContext.
  AnalysisDeclContextManager *getManager() const {
    return Manager;
  }
  
  /// Return the build options used to construct the CFG.
  CFG::BuildOptions &getCFGBuildOptions() {
    return cfgBuildOptions;
  }

  const CFG::BuildOptions &getCFGBuildOptions() const {
    return cfgBuildOptions;
  }

  /// getAddEHEdges - Return true iff we are adding exceptional edges from
  /// callExprs.  If this is false, then try/catch statements and blocks
  /// reachable from them can appear to be dead in the CFG, analysis passes must
  /// cope with that.
  bool getAddEHEdges() const { return cfgBuildOptions.AddEHEdges; }
  bool getUseUnoptimizedCFG() const {
      return !cfgBuildOptions.PruneTriviallyFalseEdges;
  }
  bool getAddImplicitDtors() const { return cfgBuildOptions.AddImplicitDtors; }
  bool getAddInitializers() const { return cfgBuildOptions.AddInitializers; }

  void registerForcedBlockExpression(const Stmt *stmt);
  const CFGBlock *getBlockForRegisteredExpression(const Stmt *stmt);

  /// \brief Get the body of the Declaration.
  Stmt *getBody() const;

  /// \brief Get the body of the Declaration.
  /// \param[out] IsAutosynthesized Specifies if the body is auto-generated
  ///             by the BodyFarm.
  Stmt *getBody(bool &IsAutosynthesized) const;

  /// \brief Checks if the body of the Decl is generated by the BodyFarm.
  ///
  /// Note, the lookup is not free. We are going to call getBody behind
  /// the scenes.
  /// \sa getBody
  bool isBodyAutosynthesized() const;

  /// \brief Checks if the body of the Decl is generated by the BodyFarm from a
  /// model file.
  ///
  /// Note, the lookup is not free. We are going to call getBody behind
  /// the scenes.
  /// \sa getBody
  bool isBodyAutosynthesizedFromModelFile() const;

  CFG *getCFG();

  CFGStmtMap *getCFGStmtMap();

  CFGReverseBlockReachabilityAnalysis *getCFGReachablityAnalysis();

  /// Return a version of the CFG without any edges pruned.
  CFG *getUnoptimizedCFG();

  void dumpCFG(bool ShowColors);

  /// \brief Returns true if we have built a CFG for this analysis context.
  /// Note that this doesn't correspond to whether or not a valid CFG exists, it
  /// corresponds to whether we *attempted* to build one.
  bool isCFGBuilt() const { return builtCFG; }

  ParentMap &getParentMap();
  PseudoConstantAnalysis *getPseudoConstantAnalysis();

  typedef const VarDecl * const * referenced_decls_iterator;

  std::pair<referenced_decls_iterator, referenced_decls_iterator>
    getReferencedBlockVars(const BlockDecl *BD);

  /// Return the ImplicitParamDecl* associated with 'self' if this
  /// AnalysisDeclContext wraps an ObjCMethodDecl.  Returns NULL otherwise.
  const ImplicitParamDecl *getSelfDecl() const;

  const StackFrameContext *getStackFrame(LocationContext const *Parent,
                                         const Stmt *S,
                                         const CFGBlock *Blk,
                                         unsigned Idx);
  
  const BlockInvocationContext *
  getBlockInvocationContext(const LocationContext *parent,
                            const BlockDecl *BD,
                            const void *ContextData);

  /// Return the specified analysis object, lazily running the analysis if
  /// necessary.  Return NULL if the analysis could not run.
  template <typename T>
  T *getAnalysis() {
    const void *tag = T::getTag();
    ManagedAnalysis *&data = getAnalysisImpl(tag);
    if (!data) {
      data = T::create(*this);
    }
    return static_cast<T*>(data);
  }
private:
  ManagedAnalysis *&getAnalysisImpl(const void* tag);

  LocationContextManager &getLocationContextManager();
};

class LocationContext : public llvm::FoldingSetNode {
public:
  enum ContextKind { StackFrame, Scope, Block };

private:
  ContextKind Kind;

  // AnalysisDeclContext can't be const since some methods may modify its
  // member.
  AnalysisDeclContext *Ctx;

  const LocationContext *Parent;

protected:
  LocationContext(ContextKind k, AnalysisDeclContext *ctx,
                  const LocationContext *parent)
    : Kind(k), Ctx(ctx), Parent(parent) {}

public:
  virtual ~LocationContext();

  ContextKind getKind() const { return Kind; }

  AnalysisDeclContext *getAnalysisDeclContext() const { return Ctx; }

  const LocationContext *getParent() const { return Parent; }

  bool isParentOf(const LocationContext *LC) const;

  const Decl *getDecl() const { return getAnalysisDeclContext()->getDecl(); }

  CFG *getCFG() const { return getAnalysisDeclContext()->getCFG(); }

  template <typename T>
  T *getAnalysis() const {
    return getAnalysisDeclContext()->getAnalysis<T>();
  }

  ParentMap &getParentMap() const {
    return getAnalysisDeclContext()->getParentMap();
  }

  const ImplicitParamDecl *getSelfDecl() const {
    return Ctx->getSelfDecl();
  }

  const StackFrameContext *getCurrentStackFrame() const;

  /// Return true if the current LocationContext has no caller context.
  virtual bool inTopFrame() const;

  virtual void Profile(llvm::FoldingSetNodeID &ID) = 0;

  void dumpStack(raw_ostream &OS, StringRef Indent = "") const;
  void dumpStack() const;

public:
  static void ProfileCommon(llvm::FoldingSetNodeID &ID,
                            ContextKind ck,
                            AnalysisDeclContext *ctx,
                            const LocationContext *parent,
                            const void *data);
};

class StackFrameContext : public LocationContext {
  // The callsite where this stack frame is established.
  const Stmt *CallSite;

  // The parent block of the callsite.
  const CFGBlock *Block;

  // The index of the callsite in the CFGBlock.
  unsigned Index;

  friend class LocationContextManager;
  StackFrameContext(AnalysisDeclContext *ctx, const LocationContext *parent,
                    const Stmt *s, const CFGBlock *blk,
                    unsigned idx)
    : LocationContext(StackFrame, ctx, parent), CallSite(s),
      Block(blk), Index(idx) {}

public:
  ~StackFrameContext() {}

  const Stmt *getCallSite() const { return CallSite; }

  const CFGBlock *getCallSiteBlock() const { return Block; }

  /// Return true if the current LocationContext has no caller context.
  bool inTopFrame() const override { return getParent() == nullptr;  }

  unsigned getIndex() const { return Index; }

  void Profile(llvm::FoldingSetNodeID &ID) override;

  static void Profile(llvm::FoldingSetNodeID &ID, AnalysisDeclContext *ctx,
                      const LocationContext *parent, const Stmt *s,
                      const CFGBlock *blk, unsigned idx) {
    ProfileCommon(ID, StackFrame, ctx, parent, s);
    ID.AddPointer(blk);
    ID.AddInteger(idx);
  }

  static bool classof(const LocationContext *Ctx) {
    return Ctx->getKind() == StackFrame;
  }
};

class ScopeContext : public LocationContext {
  const Stmt *Enter;

  friend class LocationContextManager;
  ScopeContext(AnalysisDeclContext *ctx, const LocationContext *parent,
               const Stmt *s)
    : LocationContext(Scope, ctx, parent), Enter(s) {}

public:
  ~ScopeContext() {}

  void Profile(llvm::FoldingSetNodeID &ID) override;

  static void Profile(llvm::FoldingSetNodeID &ID, AnalysisDeclContext *ctx,
                      const LocationContext *parent, const Stmt *s) {
    ProfileCommon(ID, Scope, ctx, parent, s);
  }

  static bool classof(const LocationContext *Ctx) {
    return Ctx->getKind() == Scope;
  }
};

class BlockInvocationContext : public LocationContext {
  const BlockDecl *BD;
  
  // FIXME: Come up with a more type-safe way to model context-sensitivity.
  const void *ContextData;

  friend class LocationContextManager;

  BlockInvocationContext(AnalysisDeclContext *ctx,
                         const LocationContext *parent,
                         const BlockDecl *bd, const void *contextData)
    : LocationContext(Block, ctx, parent), BD(bd), ContextData(contextData) {}

public:
  ~BlockInvocationContext() {}

  const BlockDecl *getBlockDecl() const { return BD; }
  
  const void *getContextData() const { return ContextData; }

  void Profile(llvm::FoldingSetNodeID &ID) override;

  static void Profile(llvm::FoldingSetNodeID &ID, AnalysisDeclContext *ctx,
                      const LocationContext *parent, const BlockDecl *bd,
                      const void *contextData) {
    ProfileCommon(ID, Block, ctx, parent, bd);
    ID.AddPointer(contextData);
  }

  static bool classof(const LocationContext *Ctx) {
    return Ctx->getKind() == Block;
  }
};

class LocationContextManager {
  llvm::FoldingSet<LocationContext> Contexts;
public:
  ~LocationContextManager();

  const StackFrameContext *getStackFrame(AnalysisDeclContext *ctx,
                                         const LocationContext *parent,
                                         const Stmt *s,
                                         const CFGBlock *blk, unsigned idx);

  const ScopeContext *getScope(AnalysisDeclContext *ctx,
                               const LocationContext *parent,
                               const Stmt *s);
  
  const BlockInvocationContext *
  getBlockInvocationContext(AnalysisDeclContext *ctx,
                            const LocationContext *parent,
                            const BlockDecl *BD,
                            const void *ContextData);

  /// Discard all previously created LocationContext objects.
  void clear();
private:
  template <typename LOC, typename DATA>
  const LOC *getLocationContext(AnalysisDeclContext *ctx,
                                const LocationContext *parent,
                                const DATA *d);
};

class AnalysisDeclContextManager {
  typedef llvm::DenseMap<const Decl*, AnalysisDeclContext*> ContextMap;

  ContextMap Contexts;
  LocationContextManager LocContexts;
  CFG::BuildOptions cfgBuildOptions;

  /// Pointer to an interface that can provide function bodies for
  /// declarations from external source.
  std::unique_ptr<CodeInjector> Injector;
  
  /// Flag to indicate whether or not bodies should be synthesized
  /// for well-known functions.
  bool SynthesizeBodies;

public:
  AnalysisDeclContextManager(bool useUnoptimizedCFG = false,
                             bool addImplicitDtors = false,
                             bool addInitializers = false,
                             bool addTemporaryDtors = false,
                             bool synthesizeBodies = false,
                             bool addStaticInitBranches = false,
                             bool addCXXNewAllocator = true,
                             CodeInjector* injector = nullptr);

  ~AnalysisDeclContextManager();

  AnalysisDeclContext *getContext(const Decl *D);

  bool getUseUnoptimizedCFG() const {
    return !cfgBuildOptions.PruneTriviallyFalseEdges;
  }

  CFG::BuildOptions &getCFGBuildOptions() {
    return cfgBuildOptions;
  }
  
  /// Return true if faux bodies should be synthesized for well-known
  /// functions.
  bool synthesizeBodies() const { return SynthesizeBodies; }

  const StackFrameContext *getStackFrame(AnalysisDeclContext *Ctx,
                                         LocationContext const *Parent,
                                         const Stmt *S,
                                         const CFGBlock *Blk,
                                         unsigned Idx) {
    return LocContexts.getStackFrame(Ctx, Parent, S, Blk, Idx);
  }

  // Get the top level stack frame.
  const StackFrameContext *getStackFrame(const Decl *D) {
    return LocContexts.getStackFrame(getContext(D), nullptr, nullptr, nullptr,
                                     0);
  }

  // Get a stack frame with parent.
  StackFrameContext const *getStackFrame(const Decl *D,
                                         LocationContext const *Parent,
                                         const Stmt *S,
                                         const CFGBlock *Blk,
                                         unsigned Idx) {
    return LocContexts.getStackFrame(getContext(D), Parent, S, Blk, Idx);
  }

  /// Discard all previously created AnalysisDeclContexts.
  void clear();

private:
  friend class AnalysisDeclContext;

  LocationContextManager &getLocationContextManager() {
    return LocContexts;
  }
};

} // end clang namespace
#endif