SVals.cpp

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//===-- SVals.cpp - Abstract RValues for Path-Sens. Value Tracking --------===//
//
// 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 SVal, Loc, and NonLoc, classes that represent
//  abstract r-values for use with path-sensitive value tracking.
//
//===----------------------------------------------------------------------===//
 
#include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/Expr.h"
#include "clang/AST/Type.h"
#include "clang/Basic/JsonSupport.h"
#include "clang/Basic/LLVM.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/BasicValueFactory.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SValVisitor.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SymExpr.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
#include <optional>
 
using namespace clang;
using namespace ento;
 
//===----------------------------------------------------------------------===//
// Symbol iteration within an SVal.
//===----------------------------------------------------------------------===//
 
//===----------------------------------------------------------------------===//
// Utility methods.
//===----------------------------------------------------------------------===//
 
const FunctionDecl *SVal::getAsFunctionDecl() const {
  if (std::optional<loc::MemRegionVal> X = getAs<loc::MemRegionVal>()) {
    const MemRegion* R = X->getRegion();
    if (const FunctionCodeRegion *CTR = R->getAs<FunctionCodeRegion>())
      if (const auto *FD = dyn_cast<FunctionDecl>(CTR->getDecl()))
        return FD;
  }
 
  if (auto X = getAs<nonloc::PointerToMember>()) {
    if (const auto *MD = dyn_cast_or_null<CXXMethodDecl>(X->getDecl()))
      return MD;
  }
  return nullptr;
}
 
/// If this SVal is a location (subclasses Loc) and wraps a symbol,
/// return that SymbolRef.  Otherwise return 0.
///
/// Implicit casts (ex: void* -> char*) can turn Symbolic region into Element
/// region. If that is the case, gets the underlining region.
/// When IncludeBaseRegions is set to true and the SubRegion is non-symbolic,
/// the first symbolic parent region is returned.
SymbolRef SVal::getAsLocSymbol(bool IncludeBaseRegions) const {
  // FIXME: should we consider SymbolRef wrapped in CodeTextRegion?
  if (const MemRegion *R = getAsRegion())
    if (const SymbolicRegion *SymR =
            IncludeBaseRegions ? R->getSymbolicBase()
                               : dyn_cast<SymbolicRegion>(R->StripCasts()))
      return SymR->getSymbol();
 
  return nullptr;
}
 
/// Get the symbol in the SVal or its base region.
SymbolRef SVal::getLocSymbolInBase() const {
  std::optional<loc::MemRegionVal> X = getAs<loc::MemRegionVal>();
 
  if (!X)
    return nullptr;
 
  const MemRegion *R = X->getRegion();
 
  while (const auto *SR = dyn_cast<SubRegion>(R)) {
    if (const auto *SymR = dyn_cast<SymbolicRegion>(SR))
      return SymR->getSymbol();
    else
      R = SR->getSuperRegion();
  }
 
  return nullptr;
}
 
/// If this SVal wraps a symbol return that SymbolRef.
/// Otherwise, return 0.
///
/// Casts are ignored during lookup.
/// \param IncludeBaseRegions The boolean that controls whether the search
/// should continue to the base regions if the region is not symbolic.
SymbolRef SVal::getAsSymbol(bool IncludeBaseRegions) const {
  // FIXME: should we consider SymbolRef wrapped in CodeTextRegion?
  if (std::optional<nonloc::SymbolVal> X = getAs<nonloc::SymbolVal>())
    return X->getSymbol();
 
  return getAsLocSymbol(IncludeBaseRegions);
}
 
const llvm::APSInt *SVal::getAsInteger() const {
  if (auto CI = getAs<nonloc::ConcreteInt>())
    return CI->getValue().get();
  if (auto CI = getAs<loc::ConcreteInt>())
    return CI->getValue().get();
  return nullptr;
}
 
const MemRegion *SVal::getAsRegion() const {
  if (std::optional<loc::MemRegionVal> X = getAs<loc::MemRegionVal>())
    return X->getRegion();
 
  if (std::optional<nonloc::LocAsInteger> X = getAs<nonloc::LocAsInteger>())
    return X->getLoc().getAsRegion();
 
  return nullptr;
}
 
namespace {
class TypeRetrievingVisitor
    : public FullSValVisitor<TypeRetrievingVisitor, QualType> {
private:
  const ASTContext &Context;
 
public:
  TypeRetrievingVisitor(const ASTContext &Context) : Context(Context) {}
 
  QualType VisitMemRegionVal(loc::MemRegionVal MRV) {
    return Visit(MRV.getRegion());
  }
  QualType VisitGotoLabel(loc::GotoLabel GL) {
    return QualType{Context.VoidPtrTy};
  }
  template <class ConcreteInt> QualType VisitConcreteInt(ConcreteInt CI) {
    const llvm::APSInt &Value = CI.getValue();
    if (1 == Value.getBitWidth())
      return Context.BoolTy;
    return Context.getIntTypeForBitwidth(Value.getBitWidth(), Value.isSigned());
  }
  QualType VisitLocAsInteger(nonloc::LocAsInteger LI) {
    QualType NestedType = Visit(LI.getLoc());
    if (NestedType.isNull())
      return NestedType;
 
    return Context.getIntTypeForBitwidth(LI.getNumBits(),
                                         NestedType->isSignedIntegerType());
  }
  QualType VisitCompoundVal(nonloc::CompoundVal CV) {
    return CV.getValue()->getType();
  }
  QualType VisitLazyCompoundVal(nonloc::LazyCompoundVal LCV) {
    return LCV.getRegion()->getValueType();
  }
  QualType VisitSymbolVal(nonloc::SymbolVal SV) {
    return Visit(SV.getSymbol());
  }
  QualType VisitSymbolicRegion(const SymbolicRegion *SR) {
    return Visit(SR->getSymbol());
  }
  QualType VisitAllocaRegion(const AllocaRegion *) {
    return QualType{Context.VoidPtrTy};
  }
  QualType VisitTypedRegion(const TypedRegion *TR) {
    return TR->getLocationType();
  }
  QualType VisitSymExpr(const SymExpr *SE) { return SE->getType(); }
};
} // end anonymous namespace
 
QualType SVal::getType(const ASTContext &Context) const {
  TypeRetrievingVisitor TRV{Context};
  return TRV.Visit(*this);
}
 
const MemRegion *loc::MemRegionVal::stripCasts(bool StripBaseCasts) const {
  return getRegion()->StripCasts(StripBaseCasts);
}
 
const void *nonloc::LazyCompoundVal::getStore() const {
  return static_cast<const LazyCompoundValData*>(Data)->getStore();
}
 
const TypedValueRegion *nonloc::LazyCompoundVal::getRegion() const {
  return static_cast<const LazyCompoundValData*>(Data)->getRegion();
}
 
bool nonloc::PointerToMember::isNullMemberPointer() const {
  return getPTMData().isNull();
}
 
const NamedDecl *nonloc::PointerToMember::getDecl() const {
  const auto PTMD = this->getPTMData();
  if (PTMD.isNull())
    return nullptr;
 
  const NamedDecl *ND = nullptr;
  if (const auto *NDP = dyn_cast<const NamedDecl *>(PTMD))
    ND = NDP;
  else
    ND = cast<const PointerToMemberData *>(PTMD)->getDeclaratorDecl();
 
  return ND;