Environment.h

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//===- Environment.h - Map from Stmt* to Locations/Values -------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
//  This file defined the Environment and EnvironmentManager classes.
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_ENVIRONMENT_H
#define LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_ENVIRONMENT_H
 
#include "clang/Analysis/AnalysisDeclContext.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState_Fwd.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
#include "llvm/ADT/ImmutableMap.h"
#include <utility>
 
namespace clang {
 
class Stmt;
 
namespace ento {
 
class SValBuilder;
class SymbolReaper;
 
/// An entry in the environment consists of a Stmt and an LocationContext.
/// This allows the environment to manage context-sensitive bindings,
/// which is essentially for modeling recursive function analysis, among
/// other things.
/// FIXME: Use 'Expr' instead of 'Stmt' because associating a result with a
/// non-expression statement does not make sense. Currently the environment
/// only containts 'Expr's; and there is only one easy-to-eliminate hack in
/// 'processCallExit' and 'Environment::getSVal' that constructs and handles
/// 'EnvironmentEntry' instances with a 'ReturnStmt' as the 'first' part.
class EnvironmentEntry : public std::pair<const Stmt *,
                                          const StackFrameContext *> {
public:
  EnvironmentEntry(const Stmt *s, const LocationContext *L);
 
  const Stmt *getStmt() const { return first; }
  const LocationContext *getLocationContext() const { return second; }
 
  /// Profile an EnvironmentEntry for inclusion in a FoldingSet.
  static void Profile(llvm::FoldingSetNodeID &ID,
                      const EnvironmentEntry &E) {
    ID.AddPointer(E.getStmt());
    ID.AddPointer(E.getLocationContext());
  }
 
  void Profile(llvm::FoldingSetNodeID &ID) const {
    Profile(ID, *this);
  }
};
 
/// An immutable map from EnvironmentEntries to SVals.
class Environment {
private:
  friend class EnvironmentManager;
 
  using BindingsTy = llvm::ImmutableMap<EnvironmentEntry, SVal>;
 
  BindingsTy ExprBindings;
 
  Environment(BindingsTy eb) : ExprBindings(eb) {}
 
  SVal lookupExpr(const EnvironmentEntry &E) const;
 
public:
  using iterator = BindingsTy::iterator;
 
  iterator begin() const { return ExprBindings.begin(); }
  iterator end() const { return ExprBindings.end(); }
 
  /// Fetches the current binding of the expression in the
  /// Environment.
  SVal getSVal(const EnvironmentEntry &E, SValBuilder &svalBuilder) const;
 
  /// Profile - Profile the contents of an Environment object for use
  ///  in a FoldingSet.
  static void Profile(llvm::FoldingSetNodeID& ID, const Environment* env) {
    env->ExprBindings.Profile(ID);
  }
 
  /// Profile - Used to profile the contents of this object for inclusion
  ///  in a FoldingSet.
  void Profile(llvm::FoldingSetNodeID& ID) const {
    Profile(ID, this);
  }
 
  bool operator==(const Environment& RHS) const {
    return ExprBindings == RHS.ExprBindings;
  }
 
  void printJson(raw_ostream &Out, const ASTContext &Ctx,
                 const LocationContext *LCtx = nullptr, const char *NL = "\n",
                 unsigned int Space = 0, bool IsDot = false) const;
};
 
class EnvironmentManager {
private:
  using FactoryTy = Environment::BindingsTy::Factory;
 
  FactoryTy F;
 
public:
  EnvironmentManager(llvm::BumpPtrAllocator &Allocator) : F(Allocator) {}
 
  Environment getInitialEnvironment() {
    return Environment(F.getEmptyMap());
  }
 
  /// Bind a symbolic value to the given environment entry.
  Environment bindExpr(Environment Env, const EnvironmentEntry &E, SVal V,
                       bool Invalidate);
 
  Environment removeDeadBindings(Environment Env,
                                 SymbolReaper &SymReaper,
                                 ProgramStateRef state);
};
 
} // namespace ento
 
} // namespace clang
 
#endif // LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_ENVIRONMENT_H