//===- SVals.h - Abstract Values for Static Analysis ------------*- 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 SVal, Loc, and NonLoc, classes that represent
// abstract r-values for use with path-sensitive value tracking.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_SVALS_H
#define LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_SVALS_H
#include "clang/AST/Expr.h"
#include "clang/AST/Type.h"
#include "clang/Basic/LLVM.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SymExpr.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/ADT/ImmutableList.h"
#include "llvm/ADT/PointerUnion.h"
#include "llvm/Support/Casting.h"
#include <cassert>
#include <cstdint>
#include <optional>
#include <utility>
//==------------------------------------------------------------------------==//
// Base SVal types.
//==------------------------------------------------------------------------==//
namespace clang {
class CXXBaseSpecifier;
class FunctionDecl;
class LabelDecl;
namespace ento {
class CompoundValData;
class LazyCompoundValData;
class MemRegion;
class PointerToMemberData;
class SValBuilder;
class TypedValueRegion;
namespace nonloc {
/// Sub-kinds for NonLoc values.
enum Kind {
#define NONLOC_SVAL(Id, Parent) Id ## Kind,
#include "clang/StaticAnalyzer/Core/PathSensitive/SVals.def"
};
} // namespace nonloc
namespace loc {
/// Sub-kinds for Loc values.
enum Kind {
#define LOC_SVAL(Id, Parent) Id ## Kind,
#include "clang/StaticAnalyzer/Core/PathSensitive/SVals.def"
};
} // namespace loc
/// SVal - This represents a symbolic expression, which can be either
/// an L-value or an R-value.
///
class SVal {
public:
enum BaseKind {
// The enumerators must be representable using 2 bits.
#define BASIC_SVAL(Id, Parent) Id ## Kind,
#define ABSTRACT_SVAL_WITH_KIND(Id, Parent) Id ## Kind,
#include "clang/StaticAnalyzer/Core/PathSensitive/SVals.def"
};
enum { BaseBits = 2, BaseMask = 0b11 };
protected:
const void *Data = nullptr;
/// The lowest 2 bits are a BaseKind (0 -- 3).
/// The higher bits are an unsigned "kind" value.
unsigned Kind = 0;
explicit SVal(const void *d, bool isLoc, unsigned ValKind)
: Data(d), Kind((isLoc ? LocKind : NonLocKind) | (ValKind << BaseBits)) {}
explicit SVal(BaseKind k, const void *D = nullptr) : Data(D), Kind(k) {}
public:
explicit SVal() = default;
/// Convert to the specified SVal type, asserting that this SVal is of
/// the desired type.
template <typename T> T castAs() const { return llvm::cast<T>(*this); }
/// Convert to the specified SVal type, returning std::nullopt if this SVal is
/// not of the desired type.
template <typename T> std::optional<T> getAs() const {
return llvm::dyn_cast<T>(*this);
}
unsigned getRawKind() const { return Kind; }
BaseKind getBaseKind() const { return (BaseKind) (Kind & BaseMask); }
unsigned getSubKind() const { return Kind >> BaseBits; }
// This method is required for using SVal in a FoldingSetNode. It
// extracts a unique signature for this SVal object.
void Profile(llvm::FoldingSetNodeID &ID) const {
ID.AddInteger((unsigned) getRawKind());
ID.AddPointer(Data);
}
bool operator==(SVal R) const {
return getRawKind() == R.getRawKind() && Data == R.Data;
}
bool operator!=(SVal R) const { return !(*this == R); }
bool isUnknown() const {
return getRawKind() == UnknownValKind;
}
bool isUndef() const {
return getRawKind() == UndefinedValKind;
}
bool isUnknownOrUndef() const {
return getRawKind() <= UnknownValKind;
}
bool isValid() const {
return getRawKind() > UnknownValKind;
}
bool isConstant() const;
bool isConstant(int I) const;
bool isZeroConstant() const;
/// getAsFunctionDecl - If this SVal is a MemRegionVal and wraps a
/// CodeTextRegion wrapping a FunctionDecl, return that FunctionDecl.
/// Otherwise return 0.
const FunctionDecl *getAsFunctionDecl() const;
/// If this SVal is a location and 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 getAsLocSymbol(bool IncludeBaseRegions = false) const;
/// Get the symbol in the SVal or its base region.
SymbolRef getLocSymbolInBase() const;
/// 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 getAsSymbol(bool IncludeBaseRegions = false) const;
/// If this SVal is loc::ConcreteInt or nonloc::ConcreteInt,
/// return a pointer to APSInt which is held in it.
/// Otherwise, return nullptr.
const llvm::APSInt *getAsInteger() const;
const MemRegion *getAsRegion() const;
/// printJson - Pretty-prints in JSON format.
void printJson(raw_ostream &Out, bool AddQuotes) const;
void dumpToStream(raw_ostream &OS) const;
void dump() const;
SymExpr::symbol_iterator symbol_begin() const {
const SymExpr *SE = getAsSymbol(/*IncludeBaseRegions=*/true);
if (SE)
return SE->symbol_begin();
else
return SymExpr::symbol_iterator();
}
SymExpr::symbol_iterator symbol_end() const {
return SymExpr::symbol_end();
}
/// Try to get a reasonable type for the given value.
///
/// \returns The best approximation of the value type or Null.
/// In theory, all symbolic values should be typed, but this function
/// is still a WIP and might have a few blind spots.
///
/// \note This function should not be used when the user has access to the
/// bound expression AST node as well, since AST always has exact types.
///
/// \note Loc values are interpreted as pointer rvalues for the purposes of
/// this method.
QualType getType(const ASTContext &) const;
};
inline raw_ostream &operator<<(raw_ostream &os, clang::ento::SVal V) {
V.dumpToStream(os);
return os;
}
class UndefinedVal : public SVal {
public:
UndefinedVal() : SVal(UndefinedValKind) {}
static bool classof(SVal V) { return V.getBaseKind() == UndefinedValKind; }
};
class DefinedOrUnknownSVal : public SVal {
public:
// We want calling these methods to be a compiler error since they are
// tautologically false.
bool isUndef() const = delete;
bool isValid() const = delete;
static bool classof(SVal V) { return !V.isUndef(); }
protected:
explicit DefinedOrUnknownSVal(const void *d, bool isLoc, unsigned ValKind)
: SVal(d, isLoc, ValKind) {}
explicit DefinedOrUnknownSVal(BaseKind k, void *D = nullptr) : SVal(k, D) {}
};
class UnknownVal : public DefinedOrUnknownSVal {
public:
explicit UnknownVal() : DefinedOrUnknownSVal(UnknownValKind) {}
static bool classof(SVal V) { return V.getBaseKind() == UnknownValKind; }
};
class DefinedSVal : public DefinedOrUnknownSVal {
public:
// We want calling these methods to be a compiler error since they are
// tautologically true/false.
bool isUnknown() const = delete;
bool isUnknownOrUndef() const = delete;
bool isValid() const = delete;
static bool classof(SVal V) { return !V.isUnknownOrUndef(); }
protected:
explicit DefinedSVal(const void *d, bool isLoc, unsigned ValKind)
: DefinedOrUnknownSVal(d, isLoc, ValKind) {}
};
/// Represents an SVal that is guaranteed to not be UnknownVal.
class KnownSVal : public SVal {
public:
KnownSVal(const DefinedSVal &V) : SVal(V) {}
KnownSVal(const UndefinedVal &V) : SVal(V) {}
static bool classof(SVal V) { return !V.isUnknown(); }
};
class NonLoc : public DefinedSVal {
protected:
explicit NonLoc(unsigned SubKind, const void *d)
: DefinedSVal(d, false, SubKind) {}
public:
void dumpToStream(raw_ostream &Out) const;
static bool isCompoundType(QualType T) {
return T->isArrayType() || T->isRecordType() ||
T->isAnyComplexType() || T->isVectorType();
}
static bool classof(SVal V) { return V.getBaseKind() == NonLocKind; }
};
class Loc : public DefinedSVal {
protected:
explicit Loc(unsigned SubKind, const void *D)
: DefinedSVal(const_cast<void *>(D), true, SubKind) {}
public:
void dumpToStream(raw_ostream &Out) const;
static bool isLocType(QualType T) {
return T->isAnyPointerType() || T->isBlockPointerType() ||
T->isReferenceType() || T->isNullPtrType();
}
static bool classof(SVal V) { return V.getBaseKind() == LocKind; }
};
//==------------------------------------------------------------------------==//
// Subclasses of NonLoc.
//==------------------------------------------------------------------------==//
namespace nonloc {
/// Represents symbolic expression that isn't a location.
class SymbolVal : public NonLoc {
public:
SymbolVal() = delete;
SymbolVal(SymbolRef sym) : NonLoc(SymbolValKind, sym) {
assert(sym);
assert(!Loc::isLocType(sym->getType()));
}
LLVM_ATTRIBUTE_RETURNS_NONNULL
SymbolRef getSymbol() const {
return (const SymExpr *) Data;
}
bool isExpression() const {
return !isa<SymbolData>(getSymbol());
}
static bool classof(SVal V) {
return V.getBaseKind() == NonLocKind && V.getSubKind() == SymbolValKind;
}
static bool classof(NonLoc V) { return V.getSubKind() == SymbolValKind; }
};
/// Value representing integer constant.
class ConcreteInt : public NonLoc {
public:
explicit ConcreteInt(const llvm::APSInt& V) : NonLoc(ConcreteIntKind, &V) {}
const llvm::APSInt& getValue() const {
return *static_cast<const llvm::APSInt *>(Data);
}
static bool classof(SVal V) {
return V.getBaseKind() == NonLocKind && V.getSubKind() == ConcreteIntKind;
}
static bool classof(NonLoc V) { return V.getSubKind() == ConcreteIntKind; }
};
class LocAsInteger : public NonLoc {
friend class ento::SValBuilder;
explicit LocAsInteger(const std::pair<SVal, uintptr_t> &data)
: NonLoc(LocAsIntegerKind, &data) {
// We do not need to represent loc::ConcreteInt as LocAsInteger,
// as it'd collapse into a nonloc::ConcreteInt instead.
assert(data.first.getBaseKind() == LocKind &&
(data.first.getSubKind() == loc::MemRegionValKind ||
data.first.getSubKind() == loc::GotoLabelKind));
}
public:
Loc getLoc() const {
const std::pair<SVal, uintptr_t> *D =
static_cast<const std::pair<SVal, uintptr_t> *>(Data);
return D->first.castAs<Loc>();
}
unsigned getNumBits() const {
const std::pair<SVal, uintptr_t> *D =
static_cast<const std::pair<SVal, uintptr_t> *>(Data);
return D->second;
}
static bool classof(SVal V) {
return V.getBaseKind() == NonLocKind && V.getSubKind() == LocAsIntegerKind;
}
static bool classof(NonLoc V) { return V.getSubKind() == LocAsIntegerKind; }
};
class CompoundVal : public NonLoc {
friend class ento::SValBuilder;
explicit CompoundVal(const CompoundValData *D) : NonLoc(CompoundValKind, D) {
assert(D);
}
public:
LLVM_ATTRIBUTE_RETURNS_NONNULL
const CompoundValData* getValue() const {
return static_cast<const CompoundValData *>(Data);
}
using iterator = llvm::ImmutableList<SVal>::iterator;
iterator begin() const;
iterator end() const;
static bool classof(SVal V) {
return V.getBaseKind() == NonLocKind && V.getSubKind() == CompoundValKind;
}
static bool classof(NonLoc V) { return V.getSubKind() == CompoundValKind; }
};
class LazyCompoundVal : public NonLoc {
friend class ento::SValBuilder;
explicit LazyCompoundVal(const LazyCompoundValData *D)
: NonLoc(LazyCompoundValKind, D) {
assert(D);
}
public:
LLVM_ATTRIBUTE_RETURNS_NONNULL
const LazyCompoundValData *getCVData() const {
return static_cast<const LazyCompoundValData *>(Data);
}
/// It might return null.
const void *getStore() const;
LLVM_ATTRIBUTE_RETURNS_NONNULL
const TypedValueRegion *getRegion() const;
static bool classof(SVal V) {
return V.getBaseKind() == NonLocKind &&
V.getSubKind() == LazyCompoundValKind;
}
static bool classof(NonLoc V) {
return V.getSubKind() == LazyCompoundValKind;
}
};
/// Value representing pointer-to-member.
///
/// This value is qualified as NonLoc because neither loading nor storing
/// operations are applied to it. Instead, the analyzer uses the L-value coming
/// from pointer-to-member applied to an object.
/// This SVal is represented by a NamedDecl which can be a member function
/// pointer or a member data pointer and an optional list of CXXBaseSpecifiers.
/// This list is required to accumulate the pointer-to-member cast history to
/// figure out the correct subobject field. In particular, implicit casts grow
/// this list and explicit casts like static_cast shrink this list.
class PointerToMember : public NonLoc {
friend class ento::SValBuilder;
public:
using PTMDataType =
llvm::PointerUnion<const NamedDecl *, const PointerToMemberData *>;
const PTMDataType getPTMData() const {
return PTMDataType::getFromOpaqueValue(const_cast<void *>(Data));
}
bool isNullMemberPointer() const;
const NamedDecl *getDecl() const;
template<typename AdjustedDecl>
const AdjustedDecl *getDeclAs() const {
return dyn_cast_or_null<AdjustedDecl>(getDecl());
}
using iterator = llvm::ImmutableList<const CXXBaseSpecifier *>::iterator;
iterator begin() const;
iterator end() const;
static bool classof(SVal V) {
return V.getBaseKind() == NonLocKind &&
V.getSubKind() == PointerToMemberKind;
}
static bool classof(NonLoc V) {
return V.getSubKind() == PointerToMemberKind;
}
private:
explicit PointerToMember(const PTMDataType D)
: NonLoc(PointerToMemberKind, D.getOpaqueValue()) {}
};
} // namespace nonloc
//==------------------------------------------------------------------------==//
// Subclasses of Loc.
//==------------------------------------------------------------------------==//
namespace loc {
class GotoLabel : public Loc {
public:
explicit GotoLabel(const LabelDecl *Label) : Loc(GotoLabelKind, Label) {
assert(Label);
}
const LabelDecl *getLabel() const {
return static_cast<const LabelDecl *>(Data);
}
static bool classof(SVal V) {
return V.getBaseKind() == LocKind && V.getSubKind() == GotoLabelKind;
}
static bool classof(Loc V) { return V.getSubKind() == GotoLabelKind; }
};
class MemRegionVal : public Loc {
public:
explicit MemRegionVal(const MemRegion* r) : Loc(MemRegionValKind, r) {
assert(r);
}
/// Get the underlining region.
const MemRegion *getRegion() const {
return static_cast<const MemRegion *>(Data);
}
/// Get the underlining region and strip casts.
const MemRegion* stripCasts(bool StripBaseCasts = true) const;
template <typename REGION>
const REGION* getRegionAs() const {
return dyn_cast<REGION>(getRegion());
}
bool operator==(const MemRegionVal &R) const {
return getRegion() == R.getRegion();
}
bool operator!=(const MemRegionVal &R) const {
return getRegion() != R.getRegion();
}
static bool classof(SVal V) {
return V.getBaseKind() == LocKind && V.getSubKind() == MemRegionValKind;
}
static bool classof(Loc V) { return V.getSubKind() == MemRegionValKind; }
};
class ConcreteInt : public Loc {
public:
explicit ConcreteInt(const llvm::APSInt& V) : Loc(ConcreteIntKind, &V) {}
const llvm::APSInt &getValue() const {
return *static_cast<const llvm::APSInt *>(Data);
}
static bool classof(SVal V) {
return V.getBaseKind() == LocKind && V.getSubKind() == ConcreteIntKind;
}
static bool classof(Loc V) { return V.getSubKind() == ConcreteIntKind; }
};
} // namespace loc
} // namespace ento
} // namespace clang
namespace llvm {
template <typename To, typename From>
struct CastInfo<
To, From,
std::enable_if_t<std::is_base_of<::clang::ento::SVal, From>::value>>
: public CastIsPossible<To, ::clang::ento::SVal> {
using Self = CastInfo<
To, From,
std::enable_if_t<std::is_base_of<::clang::ento::SVal, From>::value>>;
static bool isPossible(const From &V) {
return To::classof(*static_cast<const ::clang::ento::SVal *>(&V));
}
static std::optional<To> castFailed() { return std::optional<To>{}; }
static To doCast(const From &f) {
return *static_cast<const To *>(cast<::clang::ento::SVal>(&f));
}
static std::optional<To> doCastIfPossible(const From &f) {
if (!Self::isPossible(f))
return Self::castFailed();
return doCast(f);
}
};
} // namespace llvm
#endif // LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_SVALS_H