Analysis/ValueState.h

//== ValueState.h - Path-Sens. "State" for tracking valuues -----*- C++ -*--==//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This files defines SymbolID, VarBindKey, and ValueState.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_ANALYSIS_VALUESTATE_H
#define LLVM_CLANG_ANALYSIS_VALUESTATE_H

// FIXME: Reduce the number of includes.

#include "RValues.h"

#include "clang/Analysis/PathSensitive/GREngine.h"
#include "clang/AST/Expr.h"
#include "clang/AST/Decl.h"
#include "clang/AST/ASTContext.h"
#include "clang/Analysis/Analyses/LiveVariables.h"

#include "llvm/Support/Casting.h"
#include "llvm/Support/DataTypes.h"
#include "llvm/ADT/APSInt.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/ADT/ImmutableMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Streams.h"

#include <functional>

namespace clang {  

/// VarBindKey - A variant smart pointer that wraps either a ValueDecl* or a
///  Stmt*.  Use cast<> or dyn_cast<> to get actual pointer type
class VarBindKey {
  uintptr_t Raw;  
  void operator=(const VarBindKey& RHS); // Do not implement.
  
public:
  enum  Kind { IsSubExpr=0x0, IsBlkExpr=0x1, IsDecl=0x2, // L-Value Bindings.
               IsSymbol=0x3, // Symbol Bindings.
               Mask=0x3 };
  
  inline Kind getKind() const {
    return (Kind) (Raw & Mask);
  }
  
  inline void* getPtr() const { 
    assert (getKind() != IsSymbol);
    return reinterpret_cast<void*>(Raw & ~Mask);
  }
  
  inline SymbolID getSymbolID() const {
    assert (getKind() == IsSymbol);
    return Raw >> 2;
  }
  
  VarBindKey(const ValueDecl* VD)
  : Raw(reinterpret_cast<uintptr_t>(VD) | IsDecl) {
    assert(VD && "ValueDecl cannot be NULL.");
  }
  
  VarBindKey(Stmt* S, bool isBlkExpr = false) 
  : Raw(reinterpret_cast<uintptr_t>(S) | (isBlkExpr ? IsBlkExpr : IsSubExpr)){
    assert(S && "Tracked statement cannot be NULL.");
  }
  
  VarBindKey(SymbolID V)
  : Raw((V << 2) | IsSymbol) {}  
  
  bool isSymbol()  const { return getKind() == IsSymbol; }
  bool isSubExpr() const { return getKind() == IsSubExpr; }
  bool isBlkExpr() const { return getKind() == IsBlkExpr; }
  bool isDecl()    const { return getKind() == IsDecl; }
  bool isStmt()    const { return getKind() <= IsBlkExpr; }
  
  inline void Profile(llvm::FoldingSetNodeID& ID) const {
    ID.AddInteger(isSymbol() ? 1 : 0);
    
    if (isSymbol())
      ID.AddInteger(getSymbolID());
    else    
      ID.AddPointer(getPtr());
  }
  
  inline bool operator==(const VarBindKey& X) const {
    return isSymbol() ? getSymbolID() == X.getSymbolID()
    : getPtr() == X.getPtr();
  }
  
  inline bool operator!=(const VarBindKey& X) const {
    return !operator==(X);
  }
  
  inline bool operator<(const VarBindKey& X) const { 
    if (isSymbol())
      return X.isSymbol() ? getSymbolID() < X.getSymbolID() : false;
    
    return getPtr() < X.getPtr();
  }
};

//===----------------------------------------------------------------------===//
// ValueState - An ImmutableMap type Stmt*/Decl*/Symbols to RValues.
//===----------------------------------------------------------------------===//

namespace vstate {
  typedef llvm::ImmutableSet<llvm::APSInt*> IntSetTy;
  
  typedef llvm::ImmutableMap<VarBindKey,RValue> VariableBindingsTy;  
  typedef llvm::ImmutableMap<SymbolID,IntSetTy> ConstantNotEqTy;
}

/// ValueStateImpl - This class encapsulates the actual data values for
///  for a "state" in our symbolic value tracking.  It is intended to be
///  used as a functional object; that is once it is created and made
///  "persistent" in a FoldingSet its values will never change.
struct ValueStateImpl : public llvm::FoldingSetNode {
  vstate::VariableBindingsTy VariableBindings;
  vstate::ConstantNotEqTy    ConstantNotEq;
  
  /// This ctor is used when creating the first ValueStateImpl object.
  ValueStateImpl(vstate::VariableBindingsTy VB, vstate::ConstantNotEqTy CNE)
    : VariableBindings(VB), ConstantNotEq(CNE) {}
  
  /// Copy ctor - We must explicitly define this or else the "Next" ptr
  ///  in FoldingSetNode will also get copied.
  ValueStateImpl(const ValueStateImpl& RHS)
    : llvm::FoldingSetNode(),
      VariableBindings(RHS.VariableBindings),
      ConstantNotEq(RHS.ConstantNotEq) {} 
  
  /// Profile - Profile the contents of a ValueStateImpl object for use
  ///  in a FoldingSet.
  static void Profile(llvm::FoldingSetNodeID& ID, const ValueStateImpl& V) {
    V.VariableBindings.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);
  }
  
};
  
/// ValueState - This class represents a "state" in our symbolic value
///  tracking. It is really just a "smart pointer", wrapping a pointer
///  to ValueStateImpl object.  Making this class a smart pointer means that its
///  size is always the size of a pointer, which allows easy conversion to
///  void* when being handled by GREngine.  It also forces us to unique states;
///  consequently, a ValueStateImpl* with a specific address will always refer
///  to the unique state with those values.
class ValueState : public llvm::FoldingSetNode {
  ValueStateImpl* Data;
public:
  ValueState(ValueStateImpl* D) : Data(D) {}
  ValueState() : Data(0) {}  
  void operator=(ValueStateImpl* D) { Data = D; }
  
  // Accessors.  
  ValueStateImpl* getImpl() const { return Data; }

  // Typedefs.
  typedef vstate::VariableBindingsTy       VariableBindingsTy;
  typedef vstate::ConstantNotEqTy          ConstantNotEqTy;
  typedef llvm::SmallVector<ValueState,5>  BufferTy;

  // Iterators.

  typedef VariableBindingsTy::iterator vb_iterator;  
  vb_iterator begin() { return Data->VariableBindings.begin(); }
  vb_iterator end() { return Data->VariableBindings.end(); }
  
  // Profiling and equality testing.
  
  bool operator==(const ValueState& RHS) const {
    return Data == RHS.Data;
  }
  
  static void Profile(llvm::FoldingSetNodeID& ID, const ValueState& V) {
    ID.AddPointer(V.getImpl());
  }
  
  void Profile(llvm::FoldingSetNodeID& ID) const {
    Profile(ID, *this);
  }
};  
  
template<> struct GRTrait<ValueState> {
  static inline void* toPtr(ValueState St) {
    return reinterpret_cast<void*>(St.getImpl());
  }  
  static inline ValueState toState(void* P) {    
    return ValueState(static_cast<ValueStateImpl*>(P));
  }
};
    
  
class ValueStateManager {
public:
  typedef ValueState StateTy;

private:
  ValueState::VariableBindingsTy::Factory VBFactory;
  ValueState::ConstantNotEqTy::Factory    CNEFactory;
  
  /// StateSet - FoldingSet containing all the states created for analyzing
  ///  a particular function.  This is used to unique states.
  llvm::FoldingSet<ValueStateImpl> StateSet;

  /// ValueMgr - Object that manages the data for all created RValues.
  ValueManager ValMgr;

  /// SymMgr - Object that manages the symbol information.
  SymbolManager SymMgr;

  /// Alloc - A BumpPtrAllocator to allocate states.
  llvm::BumpPtrAllocator& Alloc;

  StateTy getPersistentState(const ValueState& St);
  
public:  
  ValueStateManager(ASTContext& Ctx, llvm::BumpPtrAllocator& alloc) 
    : ValMgr(Ctx, alloc), Alloc(alloc) {}
  
  StateTy getInitialState();
        
  ValueManager& getValueManager() { return ValMgr; }
  SymbolManager& getSymbolManager() { return SymMgr; }
  
  StateTy SetValue(StateTy St, Stmt* S, bool isBlkExpr, const RValue& V);
  StateTy SetValue(StateTy St, const LValue& LV, const RValue& V);

  RValue GetValue(const StateTy& St, Stmt* S, bool* hasVal = NULL);
  RValue GetValue(const StateTy& St, const LValue& LV);
    
  LValue GetLValue(const StateTy& St, Stmt* S);

  StateTy Add(StateTy St, VarBindKey K, const RValue& V);
  StateTy Remove(StateTy St, VarBindKey K);
  StateTy getPersistentState(const ValueStateImpl& Impl);
};
  
} // end clang namespace

//==------------------------------------------------------------------------==//
// Casting machinery to get cast<> and dyn_cast<> working with VarBindKey.
//==------------------------------------------------------------------------==//

namespace llvm {
  
  template<> inline bool
  isa<clang::ValueDecl,clang::VarBindKey>(const clang::VarBindKey& V) {
    return V.getKind() == clang::VarBindKey::IsDecl;
  }
  
  template<> inline bool
  isa<clang::Stmt,clang::VarBindKey>(const clang::VarBindKey& V) {
    return ((unsigned) V.getKind()) < clang::VarBindKey::IsDecl;
  }
  
  template<> struct cast_retty_impl<clang::ValueDecl,clang::VarBindKey> {
    typedef const clang::ValueDecl* ret_type;
  };
  
  template<> struct cast_retty_impl<clang::Stmt,clang::VarBindKey> {
    typedef const clang::Stmt* ret_type;
  };
  
  template<> struct simplify_type<clang::VarBindKey> {
    typedef void* SimpleType;
    static inline SimpleType getSimplifiedValue(const clang::VarBindKey &V) {
      return V.getPtr();
    }
  };
} // end llvm namespace

#endif