SValBuilder.h

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// SValBuilder.h - Construction of SVals from evaluating expressions -*- 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 defines SValBuilder, a class that defines the interface for
//  "symbolical evaluators" which construct an SVal from an expression.
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_SVALBUILDER_H
#define LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_SVALBUILDER_H
 
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclarationName.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprObjC.h"
#include "clang/AST/Type.h"
#include "clang/Analysis/CFG.h"
#include "clang/Basic/LLVM.h"
#include "clang/Basic/LangOptions.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/BasicValueFactory.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState_Fwd.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SymExpr.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
#include "llvm/ADT/ImmutableList.h"
#include <cstdint>
#include <optional>
 
namespace clang {
 
class AnalyzerOptions;
class BlockDecl;
class CXXBoolLiteralExpr;
class CXXMethodDecl;
class CXXRecordDecl;
class DeclaratorDecl;
class FunctionDecl;
class LocationContext;
class StackFrameContext;
class Stmt;
 
namespace ento {
 
class CallEvent;
class ConditionTruthVal;
class ProgramStateManager;
class StoreRef;
class SValBuilder {
  virtual void anchor();
 
protected:
  ASTContext &Context;
 
  /// Manager of APSInt values.
  BasicValueFactory BasicVals;
 
  /// Manages the creation of symbols.
  SymbolManager SymMgr;
 
  /// Manages the creation of memory regions.
  MemRegionManager MemMgr;
 
  ProgramStateManager &StateMgr;
 
  const AnalyzerOptions &AnOpts;
 
  /// The scalar type to use for array indices.
  const QualType ArrayIndexTy;
 
  /// The width of the scalar type used for array indices.
  const unsigned ArrayIndexWidth;
 
public:
  SValBuilder(llvm::BumpPtrAllocator &alloc, ASTContext &context,
              ProgramStateManager &stateMgr);
 
  virtual ~SValBuilder() = default;
 
  SVal evalCast(SVal V, QualType CastTy, QualType OriginalTy);
 
  // Handles casts of type CK_IntegralCast.
  SVal evalIntegralCast(ProgramStateRef state, SVal val, QualType castTy,
                        QualType originalType);
 
  SVal evalMinus(NonLoc val);
  SVal evalComplement(NonLoc val);
 
  /// Create a new value which represents a binary expression with two non-
  /// location operands.
  virtual SVal evalBinOpNN(ProgramStateRef state, BinaryOperator::Opcode op,
                           NonLoc lhs, NonLoc rhs, QualType resultTy) = 0;
 
  /// Create a new value which represents a binary expression with two memory
  /// location operands.
  virtual SVal evalBinOpLL(ProgramStateRef state, BinaryOperator::Opcode op,
                           Loc lhs, Loc rhs, QualType resultTy) = 0;
 
  /// Create a new value which represents a binary expression with a memory
  /// location and non-location operands. For example, this would be used to
  /// evaluate a pointer arithmetic operation.
  virtual SVal evalBinOpLN(ProgramStateRef state, BinaryOperator::Opcode op,
                           Loc lhs, NonLoc rhs, QualType resultTy) = 0;
 
  /// Evaluates a given SVal. If the SVal has only one possible (integer) value,
  /// that value is returned. Otherwise, returns NULL.
  virtual const llvm::APSInt *getKnownValue(ProgramStateRef state, SVal val) = 0;
 
  /// Tries to get the minimal possible (integer) value of a given SVal. This
  /// always returns the value of a ConcreteInt, but may return NULL if the
  /// value is symbolic and the constraint manager cannot provide a useful
  /// answer.
  virtual const llvm::APSInt *getMinValue(ProgramStateRef state, SVal val) = 0;
 
  /// Tries to get the maximal possible (integer) value of a given SVal. This
  /// always returns the value of a ConcreteInt, but may return NULL if the
  /// value is symbolic and the constraint manager cannot provide a useful
  /// answer.
  virtual const llvm::APSInt *getMaxValue(ProgramStateRef state, SVal val) = 0;
 
  /// Simplify symbolic expressions within a given SVal. Return an SVal
  /// that represents the same value, but is hopefully easier to work with
  /// than the original SVal.
  virtual SVal simplifySVal(ProgramStateRef State, SVal Val) = 0;
 
  /// Constructs a symbolic expression for two non-location values.
  SVal makeSymExprValNN(BinaryOperator::Opcode op,
                        NonLoc lhs, NonLoc rhs, QualType resultTy);
 
  SVal evalUnaryOp(ProgramStateRef state, UnaryOperator::Opcode opc,
                 SVal operand, QualType type);
 
  SVal evalBinOp(ProgramStateRef state, BinaryOperator::Opcode op,
                 SVal lhs, SVal rhs, QualType type);
 
  /// \return Whether values in \p lhs and \p rhs are equal at \p state.
  ConditionTruthVal areEqual(ProgramStateRef state, SVal lhs, SVal rhs);
 
  SVal evalEQ(ProgramStateRef state, SVal lhs, SVal rhs);
 
  DefinedOrUnknownSVal evalEQ(ProgramStateRef state, DefinedOrUnknownSVal lhs,
                              DefinedOrUnknownSVal rhs);
 
  ASTContext &getContext() { return Context; }
  const ASTContext &getContext() const { return Context; }
 
  ProgramStateManager &getStateManager() { return StateMgr; }
 
  QualType getConditionType() const {
    return Context.getLangOpts().CPlusPlus ? Context.BoolTy : Context.IntTy;
  }
 
  QualType getArrayIndexType() const {
    return ArrayIndexTy;
  }
 
  BasicValueFactory &getBasicValueFactory() { return BasicVals; }
  const BasicValueFactory &getBasicValueFactory() const { return BasicVals; }
 
  SymbolManager &getSymbolManager() { return SymMgr; }
  const SymbolManager &getSymbolManager() const { return SymMgr; }
 
  MemRegionManager &getRegionManager() { return MemMgr; }
  const MemRegionManager &getRegionManager() const { return MemMgr; }
 
  const AnalyzerOptions &getAnalyzerOptions() const { return AnOpts; }
 
  // Forwarding methods to SymbolManager.
 
  const SymbolConjured *conjureSymbol(ConstCFGElementRef Elem,
                                      const LocationContext *LCtx,
                                      QualType type, unsigned visitCount,
                                      const void *symbolTag = nullptr) {
    return SymMgr.conjureSymbol(Elem, LCtx, type, visitCount, symbolTag);
  }
 
  /// Construct an SVal representing '0' for the specified type.
  DefinedOrUnknownSVal makeZeroVal(QualType type);
 
  /// Make a unique symbol for value of region.
  DefinedOrUnknownSVal getRegionValueSymbolVal(const TypedValueRegion *region);
 
  /// Create a new symbol with a unique 'name'.
  ///
  /// We resort to conjured symbols when we cannot construct a derived symbol.
  /// The advantage of symbols derived/built from other symbols is that we
  /// preserve the relation between related(or even equivalent) expressions, so
  /// conjured symbols should be used sparingly.
  DefinedOrUnknownSVal conjureSymbolVal(const void *symbolTag,
                                        ConstCFGElementRef elem,
                                        const LocationContext *LCtx,
                                        unsigned count);
  DefinedOrUnknownSVal conjureSymbolVal(const void *symbolTag,
                                        ConstCFGElementRef elem,
                                        const LocationContext *LCtx,
                                        QualType type, unsigned count);
  DefinedOrUnknownSVal conjureSymbolVal(ConstCFGElementRef elem,
                                        const LocationContext *LCtx,
                                        QualType type, unsigned visitCount);
  DefinedOrUnknownSVal conjureSymbolVal(const CallEvent &call, QualType type,
                                        unsigned visitCount,
                                        const void *symbolTag = nullptr);
  DefinedOrUnknownSVal conjureSymbolVal(const CallEvent &call,
                                        unsigned visitCount,
                                        const void *symbolTag = nullptr);
 
  /// Conjure a symbol representing heap allocated memory region.
  DefinedSVal getConjuredHeapSymbolVal(ConstCFGElementRef elem,
                                       const LocationContext *LCtx,
                                       QualType type, unsigned Count);
 
  /// Create an SVal representing the result of an alloca()-like call, that is,
  /// an AllocaRegion on the stack.
  ///
  /// After calling this function, it's a good idea to set the extent of the
  /// returned AllocaRegion.
  loc::MemRegionVal getAllocaRegionVal(const Expr *E,
                                       const LocationContext *LCtx,
                                       unsigned Count);
 
  DefinedOrUnknownSVal getDerivedRegionValueSymbolVal(
      SymbolRef parentSymbol, const TypedValueRegion *region);
 
  DefinedSVal getMetadataSymbolVal(const void *symbolTag,
                                   const MemRegion *region,
                                   const Expr *expr, QualType type,
                                   const LocationContext *LCtx,
                                   unsigned count);
 
  DefinedSVal getMemberPointer(const NamedDecl *ND);
 
  DefinedSVal getFunctionPointer(const FunctionDecl *func);
 
  DefinedSVal getBlockPointer(const BlockDecl *block, CanQualType locTy,
                              const LocationContext *locContext,
                              unsigned blockCount);
 
  /// Returns the value of \p E, if it can be determined in a non-path-sensitive
  /// manner.
  ///
  /// If \p E is not a constant or cannot be modeled, returns \c std::nullopt.
  std::optional<SVal> getConstantVal(const Expr *E);
 
  NonLoc makeCompoundVal(QualType type, llvm::ImmutableList<SVal> vals) {
    return nonloc::CompoundVal(BasicVals.getCompoundValData(type, vals));
  }
 
  NonLoc makeLazyCompoundVal(const StoreRef &store,
                             const TypedValueRegion *region) {
    return nonloc::LazyCompoundVal(
        BasicVals.getLazyCompoundValData(store, region));
  }
 
  NonLoc makePointerToMember(const DeclaratorDecl *DD) {
    return nonloc::PointerToMember(DD);
  }
 
  NonLoc makePointerToMember(const PointerToMemberData *PTMD) {
    return nonloc::PointerToMember(PTMD);
  }
 
  NonLoc makeZeroArrayIndex() {
    return nonloc::ConcreteInt(BasicVals.getValue(0, ArrayIndexTy));
  }
 
  NonLoc makeArrayIndex(uint64_t idx) {
    return nonloc::ConcreteInt(BasicVals.getValue(idx, ArrayIndexTy));
  }
 
  SVal convertToArrayIndex(SVal val);
 
  nonloc::ConcreteInt makeIntVal(const IntegerLiteral* integer) {
    return nonloc::ConcreteInt(
        BasicVals.getValue(integer->getValue(),
                     integer->getType()->isUnsignedIntegerOrEnumerationType()));
  }
 
  nonloc::ConcreteInt makeBoolVal(const ObjCBoolLiteralExpr *boolean) {
    return makeTruthVal(boolean->getValue(), boolean->getType());
  }
 
  nonloc::ConcreteInt makeBoolVal(const CXXBoolLiteralExpr *boolean);
 
  nonloc::ConcreteInt makeIntVal(const llvm::APSInt& integer) {
    return nonloc::ConcreteInt(BasicVals.getValue(integer));
  }
 
  loc::ConcreteInt makeIntLocVal(const llvm::APSInt &integer) {
    return loc::ConcreteInt(BasicVals.getValue(integer));
  }
 
  NonLoc makeIntVal(const llvm::APInt& integer, bool isUnsigned) {
    return nonloc::ConcreteInt(BasicVals.getValue(integer, isUnsigned));
  }
 
  DefinedSVal makeIntVal(uint64_t integer, QualType type) {
    if (Loc::isLocType(type))
      return loc::ConcreteInt(BasicVals.getValue(integer, type));
 
    return nonloc::ConcreteInt(BasicVals.getValue(integer, type));
  }
 
  NonLoc makeIntVal(uint64_t integer, bool isUnsigned) {
    return nonloc::ConcreteInt(BasicVals.getIntValue(integer, isUnsigned));
  }
 
  NonLoc makeIntValWithWidth(QualType ptrType, uint64_t integer) {
    return nonloc::ConcreteInt(BasicVals.getValue(integer, ptrType));
  }
 
  NonLoc makeLocAsInteger(Loc loc, unsigned bits) {
    return nonloc::LocAsInteger(BasicVals.getPersistentSValWithData(loc, bits));
  }
 
  nonloc::SymbolVal makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op,
                               APSIntPtr rhs, QualType type);
 
  nonloc::SymbolVal makeNonLoc(APSIntPtr rhs, BinaryOperator::Opcode op,
                               const SymExpr *lhs, QualType type);
 
  nonloc::SymbolVal makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op,
                               const SymExpr *rhs, QualType type);
 
  NonLoc makeNonLoc(const SymExpr *operand, UnaryOperator::Opcode op,
                    QualType type);
 
  /// Create a NonLoc value for cast.
  nonloc::SymbolVal makeNonLoc(const SymExpr *operand, QualType fromTy,
                               QualType toTy);
 
  nonloc::ConcreteInt makeTruthVal(bool b, QualType type) {
    return nonloc::ConcreteInt(BasicVals.getTruthValue(b, type));
  }
 
  nonloc::ConcreteInt makeTruthVal(bool b) {
    return nonloc::ConcreteInt(BasicVals.getTruthValue(b));
  }
 
  /// Create NULL pointer, with proper pointer bit-width for given address
  /// space.
  /// \param type pointer type.
  loc::ConcreteInt makeNullWithType(QualType type) {
    // We cannot use the `isAnyPointerType()`.
    assert((type->isPointerType() || type->isObjCObjectPointerType() ||
            type->isBlockPointerType() || type->isNullPtrType() ||
            type->isReferenceType()) &&
           "makeNullWithType must use pointer type");
 
    // The `sizeof(T&)` is `sizeof(T)`, thus we replace the reference with a
    // pointer. Here we assume that references are actually implemented by
    // pointers under-the-hood.
    type = type->isReferenceType()
               ? Context.getPointerType(type->getPointeeType())
               : type;
    return loc::ConcreteInt(BasicVals.getZeroWithTypeSize(type));
  }
 
  loc::MemRegionVal makeLoc(SymbolRef sym) {
    return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
  }
 
  loc::MemRegionVal makeLoc(const MemRegion *region) {
    return loc::MemRegionVal(region);
  }
 
  loc::GotoLabel makeLoc(const AddrLabelExpr *expr) {
    return loc::GotoLabel(expr->getLabel());
  }
 
  loc::ConcreteInt makeLoc(const llvm::APSInt &integer) {
    return loc::ConcreteInt(BasicVals.getValue(integer));
  }
 
  /// Return MemRegionVal on success cast, otherwise return std::nullopt.
  std::optional<loc::MemRegionVal>
  getCastedMemRegionVal(const MemRegion *region, QualType type);
 
  /// Make an SVal that represents the given symbol. This follows the convention
  /// of representing Loc-type symbols (symbolic pointers and references)
  /// as Loc values wrapping the symbol rather than as plain symbol values.
  DefinedSVal makeSymbolVal(SymbolRef Sym) {
    if (Loc::isLocType(Sym->getType()))
      return makeLoc(Sym);
    return nonloc::SymbolVal(Sym);
  }
 
  /// Return a memory region for the 'this' object reference.
  loc::MemRegionVal getCXXThis(const CXXMethodDecl *D,
                               const StackFrameContext *SFC);
 
  /// Return a memory region for the 'this' object reference.
  loc::MemRegionVal getCXXThis(const CXXRecordDecl *D,
                               const StackFrameContext *SFC);
};
 
SValBuilder* createSimpleSValBuilder(llvm::BumpPtrAllocator &alloc,
                                     ASTContext &context,
                                     ProgramStateManager &stateMgr);
 
} // namespace ento
 
} // namespace clang
 
#endif // LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_SVALBUILDER_H