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llvm / llvm-project / cbd3801acfa4ace50df8d0eba275fc3bd6d3f1ac / . / clang / lib / StaticAnalyzer / Core / RegionStore.cpp
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//== RegionStore.cpp - Field-sensitive store model --------------*- 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 a basic region store model. In this model, we do have field
// sensitivity. But we assume nothing about the heap shape. So recursive data
// structures are largely ignored. Basically we do 1-limiting analysis.
// Parameter pointers are assumed with no aliasing. Pointee objects of
// parameters are created lazily.
//
//===----------------------------------------------------------------------===//
#include "clang/AST/Attr.h"
#include "clang/AST/CharUnits.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/Analysis/Analyses/LiveVariables.h"
#include "clang/Analysis/AnalysisDeclContext.h"
#include "clang/Basic/JsonSupport.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
#include "llvm/ADT/ImmutableMap.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/TimeProfiler.h"
#include "llvm/Support/raw_ostream.h"
#include <optional>
#include <utility>
using namespace clang;
using namespace ento;
//===----------------------------------------------------------------------===//
// Representation of binding keys.
//===----------------------------------------------------------------------===//
namespace {
class BindingKey {
public:
enum Kind { Default = 0x0, Direct = 0x1 };
private:
enum { Symbolic = 0x2 };
llvm::PointerIntPair<const MemRegion *, 2> P;
uint64_t Data;
/// Create a key for a binding to region \p r, which has a symbolic offset
/// from region \p Base.
explicit BindingKey(const SubRegion *r, const SubRegion *Base, Kind k)
: P(r, k | Symbolic), Data(reinterpret_cast<uintptr_t>(Base)) {
assert(r && Base && "Must have known regions.");
assert(getConcreteOffsetRegion() == Base && "Failed to store base region");
}
/// Create a key for a binding at \p offset from base region \p r.
explicit BindingKey(const MemRegion *r, uint64_t offset, Kind k)
: P(r, k), Data(offset) {
assert(r && "Must have known regions.");
assert(getOffset() == offset && "Failed to store offset");
assert((r == r->getBaseRegion() ||
isa<ObjCIvarRegion, CXXDerivedObjectRegion>(r)) &&
"Not a base");
}
public:
bool isDirect() const { return P.getInt() & Direct; }
bool isDefault() const { return !isDirect(); }
bool hasSymbolicOffset() const { return P.getInt() & Symbolic; }
const MemRegion *getRegion() const { return P.getPointer(); }
uint64_t getOffset() const {
assert(!hasSymbolicOffset());
return Data;
}
const SubRegion *getConcreteOffsetRegion() const {
assert(hasSymbolicOffset());
return reinterpret_cast<const SubRegion *>(static_cast<uintptr_t>(Data));
}
const MemRegion *getBaseRegion() const {
if (hasSymbolicOffset())
return getConcreteOffsetRegion()->getBaseRegion();
return getRegion()->getBaseRegion();
}
void Profile(llvm::FoldingSetNodeID& ID) const {
ID.AddPointer(P.getOpaqueValue());
ID.AddInteger(Data);
}
static BindingKey Make(const MemRegion *R, Kind k);
bool operator<(const BindingKey &X) const {
if (P.getOpaqueValue() < X.P.getOpaqueValue())
return true;
if (P.getOpaqueValue() > X.P.getOpaqueValue())
return false;
return Data < X.Data;
}
bool operator==(const BindingKey &X) const {
return P.getOpaqueValue() == X.P.getOpaqueValue() &&
Data == X.Data;
}
LLVM_DUMP_METHOD void dump() const;
};
std::string locDescr(Loc L) {
std::string S;
llvm::raw_string_ostream OS(S);
L.dumpToStream(OS);
return OS.str();
}
} // end anonymous namespace
BindingKey BindingKey::Make(const MemRegion *R, Kind k) {
const RegionOffset &RO = R->getAsOffset();
if (RO.hasSymbolicOffset())
return BindingKey(cast<SubRegion>(R), cast<SubRegion>(RO.getRegion()), k);
return BindingKey(RO.getRegion(), RO.getOffset(), k);
}
namespace llvm {
static inline raw_ostream &operator<<(raw_ostream &Out, BindingKey K) {
Out << "\"kind\": \"" << (K.isDirect() ? "Direct" : "Default")
<< "\", \"offset\": ";
if (!K.hasSymbolicOffset())
Out << K.getOffset();
else
Out << "null";
return Out;
}
} // namespace llvm
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
void BindingKey::dump() const { llvm::errs() << *this; }
#endif
//===----------------------------------------------------------------------===//
// Actual Store type.
//===----------------------------------------------------------------------===//
typedef llvm::ImmutableMap<BindingKey, SVal> ClusterBindings;
typedef llvm::ImmutableMapRef<BindingKey, SVal> ClusterBindingsRef;
typedef std::pair<BindingKey, SVal> BindingPair;
typedef llvm::ImmutableMap<const MemRegion *, ClusterBindings>
RegionBindings;
namespace {
class RegionBindingsRef : public llvm::ImmutableMapRef<const MemRegion *,
ClusterBindings> {
ClusterBindings::Factory *CBFactory;
// This flag indicates whether the current bindings are within the analysis
// that has started from main(). It affects how we perform loads from
// global variables that have initializers: if we have observed the
// program execution from the start and we know that these variables
// have not been overwritten yet, we can be sure that their initializers
// are still relevant. This flag never gets changed when the bindings are
// updated, so it could potentially be moved into RegionStoreManager
// (as if it's the same bindings but a different loading procedure)
// however that would have made the manager needlessly stateful.
bool IsMainAnalysis;
public:
typedef llvm::ImmutableMapRef<const MemRegion *, ClusterBindings>
ParentTy;
RegionBindingsRef(ClusterBindings::Factory &CBFactory,
const RegionBindings::TreeTy *T,
RegionBindings::TreeTy::Factory *F,
bool IsMainAnalysis)
: llvm::ImmutableMapRef<const MemRegion *, ClusterBindings>(T, F),
CBFactory(&CBFactory), IsMainAnalysis(IsMainAnalysis) {}
RegionBindingsRef(const ParentTy &P,
ClusterBindings::Factory &CBFactory,
bool IsMainAnalysis)
: llvm::ImmutableMapRef<const MemRegion *, ClusterBindings>(P),
CBFactory(&CBFactory), IsMainAnalysis(IsMainAnalysis) {}
RegionBindingsRef add(key_type_ref K, data_type_ref D) const {
return RegionBindingsRef(static_cast<const ParentTy *>(this)->add(K, D),
*CBFactory, IsMainAnalysis);
}
RegionBindingsRef remove(key_type_ref K) const {
return RegionBindingsRef(static_cast<const ParentTy *>(this)->remove(K),
*CBFactory, IsMainAnalysis);
}
RegionBindingsRef addBinding(BindingKey K, SVal V) const;
RegionBindingsRef addBinding(const MemRegion *R,
BindingKey::Kind k, SVal V) const;
const SVal *lookup(BindingKey K) const;
const SVal *lookup(const MemRegion *R, BindingKey::Kind k) const;
using llvm::ImmutableMapRef<const MemRegion *, ClusterBindings>::lookup;
RegionBindingsRef removeBinding(BindingKey K);
RegionBindingsRef removeBinding(const MemRegion *R,
BindingKey::Kind k);
RegionBindingsRef removeBinding(const MemRegion *R) {
return removeBinding(R, BindingKey::Direct).
removeBinding(R, BindingKey::Default);
}
std::optional<SVal> getDirectBinding(const MemRegion *R) const;
/// getDefaultBinding - Returns an SVal* representing an optional default
/// binding associated with a region and its subregions.
std::optional<SVal> getDefaultBinding(const MemRegion *R) const;
/// Return the internal tree as a Store.
Store asStore() const {
llvm::PointerIntPair<Store, 1, bool> Ptr = {
asImmutableMap().getRootWithoutRetain(), IsMainAnalysis};
return reinterpret_cast<Store>(Ptr.getOpaqueValue());
}
bool isMainAnalysis() const {
return IsMainAnalysis;
}
void printJson(raw_ostream &Out, const char *NL = "\n",
unsigned int Space = 0, bool IsDot = false) const {
using namespace llvm;
DenseMap<const MemRegion *, std::string> StringifyCache;
auto ToString = [&StringifyCache](const MemRegion *R) {
auto [Place, Inserted] = StringifyCache.try_emplace(R);
if (!Inserted)
return Place->second;
std::string Res;
raw_string_ostream OS(Res);
OS << R;
Place->second = Res;
return Res;
};
using Cluster =
std::pair<const MemRegion *, ImmutableMap<BindingKey, SVal>>;
using Binding = std::pair<BindingKey, SVal>;
const auto MemSpaceBeforeRegionName = [&ToString](const Cluster *L,
const Cluster *R) {
if (isa<MemSpaceRegion>(L->first) && !isa<MemSpaceRegion>(R->first))
return true;
if (!isa<MemSpaceRegion>(L->first) && isa<MemSpaceRegion>(R->first))
return false;
return ToString(L->first) < ToString(R->first);
};
const auto SymbolicBeforeOffset = [&ToString](const BindingKey &L,
const BindingKey &R) {
if (L.hasSymbolicOffset() && !R.hasSymbolicOffset())
return true;
if (!L.hasSymbolicOffset() && R.hasSymbolicOffset())
return false;
if (L.hasSymbolicOffset() && R.hasSymbolicOffset())
return ToString(L.getRegion()) < ToString(R.getRegion());
return L.getOffset() < R.getOffset();
};
const auto DefaultBindingBeforeDirectBindings =
[&SymbolicBeforeOffset](const Binding *LPtr, const Binding *RPtr) {
const BindingKey &L = LPtr->first;
const BindingKey &R = RPtr->first;
if (L.isDefault() && !R.isDefault())
return true;
if (!L.isDefault() && R.isDefault())
return false;
assert(L.isDefault() == R.isDefault());
return SymbolicBeforeOffset(L, R);
};
const auto AddrOf = [](const auto &Item) { return &Item; };
std::vector<const Cluster *> SortedClusters;
SortedClusters.reserve(std::distance(begin(), end()));
append_range(SortedClusters, map_range(*this, AddrOf));
llvm::sort(SortedClusters, MemSpaceBeforeRegionName);
for (auto [Idx, C] : llvm::enumerate(SortedClusters)) {
const auto &[BaseRegion, Bindings] = *C;
Indent(Out, Space, IsDot)
<< "{ \"cluster\": \"" << BaseRegion << "\", \"pointer\": \""
<< (const void *)BaseRegion << "\", \"items\": [" << NL;
std::vector<const Binding *> SortedBindings;
SortedBindings.reserve(std::distance(Bindings.begin(), Bindings.end()));
append_range(SortedBindings, map_range(Bindings, AddrOf));
llvm::sort(SortedBindings, DefaultBindingBeforeDirectBindings);
++Space;
for (auto [Idx, B] : llvm::enumerate(SortedBindings)) {
const auto &[Key, Value] = *B;
Indent(Out, Space, IsDot) << "{ " << Key << ", \"value\": ";
Value.printJson(Out, /*AddQuotes=*/true);
Out << " }";
if (Idx != SortedBindings.size() - 1)
Out << ',';
Out << NL;
}
--Space;
Indent(Out, Space, IsDot) << "]}";
if (Idx != SortedClusters.size() - 1)
Out << ',';
Out << NL;
}
}
LLVM_DUMP_METHOD void dump() const { printJson(llvm::errs()); }
};
} // end anonymous namespace
typedef const RegionBindingsRef& RegionBindingsConstRef;
std::optional<SVal>
RegionBindingsRef::getDirectBinding(const MemRegion *R) const {
const SVal *V = lookup(R, BindingKey::Direct);
return V ? std::optional<SVal>(*V) : std::nullopt;
}
std::optional<SVal>
RegionBindingsRef::getDefaultBinding(const MemRegion *R) const {
const SVal *V = lookup(R, BindingKey::Default);
return V ? std::optional<SVal>(*V) : std::nullopt;
}
RegionBindingsRef RegionBindingsRef::addBinding(BindingKey K, SVal V) const {
const MemRegion *Base = K.getBaseRegion();
const ClusterBindings *ExistingCluster = lookup(Base);
ClusterBindings Cluster =
(ExistingCluster ? *ExistingCluster : CBFactory->getEmptyMap());
ClusterBindings NewCluster = CBFactory->add(Cluster, K, V);
return add(Base, NewCluster);
}
RegionBindingsRef RegionBindingsRef::addBinding(const MemRegion *R,
BindingKey::Kind k,
SVal V) const {
return addBinding(BindingKey::Make(R, k), V);
}
const SVal *RegionBindingsRef::lookup(BindingKey K) const {
const ClusterBindings *Cluster = lookup(K.getBaseRegion());
if (!Cluster)
return nullptr;
return Cluster->lookup(K);
}
const SVal *RegionBindingsRef::lookup(const MemRegion *R,
BindingKey::Kind k) const {
return lookup(BindingKey::Make(R, k));
}
RegionBindingsRef RegionBindingsRef::removeBinding(BindingKey K) {
const MemRegion *Base = K.getBaseRegion();
const ClusterBindings *Cluster = lookup(Base);
if (!Cluster)
return *this;
ClusterBindings NewCluster = CBFactory->remove(*Cluster, K);
if (NewCluster.isEmpty())
return remove(Base);
return add(Base, NewCluster);
}
RegionBindingsRef RegionBindingsRef::removeBinding(const MemRegion *R,
BindingKey::Kind k){
return removeBinding(BindingKey::Make(R, k));
}
//===----------------------------------------------------------------------===//
// Main RegionStore logic.
//===----------------------------------------------------------------------===//
namespace {
class InvalidateRegionsWorker;
class RegionStoreManager : public StoreManager {
public:
RegionBindings::Factory RBFactory;
mutable ClusterBindings::Factory CBFactory;
typedef std::vector<SVal> SValListTy;
private:
typedef llvm::DenseMap<const LazyCompoundValData *,
SValListTy> LazyBindingsMapTy;
LazyBindingsMapTy LazyBindingsMap;
/// The largest number of fields a struct can have and still be
/// considered "small".
///
/// This is currently used to decide whether or not it is worth "forcing" a
/// LazyCompoundVal on bind.
///
/// This is controlled by 'region-store-small-struct-limit' option.
/// To disable all small-struct-dependent behavior, set the option to "0".
unsigned SmallStructLimit;
/// The largest number of element an array can have and still be
/// considered "small".
///
/// This is currently used to decide whether or not it is worth "forcing" a
/// LazyCompoundVal on bind.
///
/// This is controlled by 'region-store-small-struct-limit' option.
/// To disable all small-struct-dependent behavior, set the option to "0".
unsigned SmallArrayLimit;
/// A helper used to populate the work list with the given set of
/// regions.
void populateWorkList(InvalidateRegionsWorker &W,
ArrayRef<SVal> Values,
InvalidatedRegions *TopLevelRegions);
public:
RegionStoreManager(ProgramStateManager &mgr)
: StoreManager(mgr), RBFactory(mgr.getAllocator()),
CBFactory(mgr.getAllocator()), SmallStructLimit(0), SmallArrayLimit(0) {
ExprEngine &Eng = StateMgr.getOwningEngine();
AnalyzerOptions &Options = Eng.getAnalysisManager().options;
SmallStructLimit = Options.RegionStoreSmallStructLimit;
SmallArrayLimit = Options.RegionStoreSmallArrayLimit;
}
/// setImplicitDefaultValue - Set the default binding for the provided
/// MemRegion to the value implicitly defined for compound literals when
/// the value is not specified.
RegionBindingsRef setImplicitDefaultValue(RegionBindingsConstRef B,
const MemRegion *R, QualType T);
/// ArrayToPointer - Emulates the "decay" of an array to a pointer
/// type. 'Array' represents the lvalue of the array being decayed
/// to a pointer, and the returned SVal represents the decayed
/// version of that lvalue (i.e., a pointer to the first element of
/// the array). This is called by ExprEngine when evaluating
/// casts from arrays to pointers.
SVal ArrayToPointer(Loc Array, QualType ElementTy) override;
/// Creates the Store that correctly represents memory contents before
/// the beginning of the analysis of the given top-level stack frame.
StoreRef getInitialStore(const LocationContext *InitLoc) override {
bool IsMainAnalysis = false;
if (const auto *FD = dyn_cast<FunctionDecl>(InitLoc->getDecl()))
IsMainAnalysis = FD->isMain() && !Ctx.getLangOpts().CPlusPlus;
return StoreRef(RegionBindingsRef(
RegionBindingsRef::ParentTy(RBFactory.getEmptyMap(), RBFactory),
CBFactory, IsMainAnalysis).asStore(), *this);
}
//===-------------------------------------------------------------------===//
// Binding values to regions.
//===-------------------------------------------------------------------===//
RegionBindingsRef invalidateGlobalRegion(MemRegion::Kind K, const Stmt *S,
unsigned Count,
const LocationContext *LCtx,
RegionBindingsRef B,
InvalidatedRegions *Invalidated);
StoreRef invalidateRegions(Store store, ArrayRef<SVal> Values, const Stmt *S,
unsigned Count, const LocationContext *LCtx,
const CallEvent *Call, InvalidatedSymbols &IS,
RegionAndSymbolInvalidationTraits &ITraits,
InvalidatedRegions *Invalidated,
InvalidatedRegions *InvalidatedTopLevel) override;
bool scanReachableSymbols(Store S, const MemRegion *R,
ScanReachableSymbols &Callbacks) override;
RegionBindingsRef removeSubRegionBindings(RegionBindingsConstRef B,
const SubRegion *R);
std::optional<SVal>
getConstantValFromConstArrayInitializer(RegionBindingsConstRef B,
const ElementRegion *R);
std::optional<SVal>
getSValFromInitListExpr(const InitListExpr *ILE,
const SmallVector<uint64_t, 2> &ConcreteOffsets,
QualType ElemT);
SVal getSValFromStringLiteral(const StringLiteral *SL, uint64_t Offset,
QualType ElemT);
public: // Part of public interface to class.
StoreRef Bind(Store store, Loc LV, SVal V) override {
return StoreRef(bind(getRegionBindings(store), LV, V).asStore(), *this);
}
RegionBindingsRef bind(RegionBindingsConstRef B, Loc LV, SVal V);
// BindDefaultInitial is only used to initialize a region with
// a default value.
StoreRef BindDefaultInitial(Store store, const MemRegion *R,
SVal V) override {
RegionBindingsRef B = getRegionBindings(store);
// Use other APIs when you have to wipe the region that was initialized
// earlier.
assert(!(B.getDefaultBinding(R) || B.getDirectBinding(R)) &&
"Double initialization!");
B = B.addBinding(BindingKey::Make(R, BindingKey::Default), V);
return StoreRef(B.asImmutableMap().getRootWithoutRetain(), *this);
}
// BindDefaultZero is used for zeroing constructors that may accidentally
// overwrite existing bindings.
StoreRef BindDefaultZero(Store store, const MemRegion *R) override {
// FIXME: The offsets of empty bases can be tricky because of
// of the so called "empty base class optimization".
// If a base class has been optimized out
// we should not try to create a binding, otherwise we should.
// Unfortunately, at the moment ASTRecordLayout doesn't expose
// the actual sizes of the empty bases
// and trying to infer them from offsets/alignments
// seems to be error-prone and non-trivial because of the trailing padding.
// As a temporary mitigation we don't create bindings for empty bases.
if (const auto *BR = dyn_cast<CXXBaseObjectRegion>(R))
if (BR->getDecl()->isEmpty())
return StoreRef(store, *this);
RegionBindingsRef B = getRegionBindings(store);
SVal V = svalBuilder.makeZeroVal(Ctx.CharTy);
B = removeSubRegionBindings(B, cast<SubRegion>(R));
B = B.addBinding(BindingKey::Make(R, BindingKey::Default), V);
return StoreRef(B.asImmutableMap().getRootWithoutRetain(), *this);
}
/// Attempt to extract the fields of \p LCV and bind them to the struct region
/// \p R.
///
/// This path is used when it seems advantageous to "force" loading the values
/// within a LazyCompoundVal to bind memberwise to the struct region, rather
/// than using a Default binding at the base of the entire region. This is a
/// heuristic attempting to avoid building long chains of LazyCompoundVals.
///
/// \returns The updated store bindings, or \c std::nullopt if binding
/// non-lazily would be too expensive.
std::optional<RegionBindingsRef>
tryBindSmallStruct(RegionBindingsConstRef B, const TypedValueRegion *R,
const RecordDecl *RD, nonloc::LazyCompoundVal LCV);
/// BindStruct - Bind a compound value to a structure.
RegionBindingsRef bindStruct(RegionBindingsConstRef B,
const TypedValueRegion* R, SVal V);
/// BindVector - Bind a compound value to a vector.
RegionBindingsRef bindVector(RegionBindingsConstRef B,
const TypedValueRegion* R, SVal V);
std::optional<RegionBindingsRef>
tryBindSmallArray(RegionBindingsConstRef B, const TypedValueRegion *R,
const ArrayType *AT, nonloc::LazyCompoundVal LCV);
RegionBindingsRef bindArray(RegionBindingsConstRef B,
const TypedValueRegion* R,
SVal V);
/// Clears out all bindings in the given region and assigns a new value
/// as a Default binding.
RegionBindingsRef bindAggregate(RegionBindingsConstRef B,
const TypedRegion *R,
SVal DefaultVal);
/// Create a new store with the specified binding removed.
/// \param ST the original store, that is the basis for the new store.
/// \param L the location whose binding should be removed.
StoreRef killBinding(Store ST, Loc L) override;
void incrementReferenceCount(Store store) override {
getRegionBindings(store).manualRetain();
}
/// If the StoreManager supports it, decrement the reference count of
/// the specified Store object. If the reference count hits 0, the memory
/// associated with the object is recycled.
void decrementReferenceCount(Store store) override {
getRegionBindings(store).manualRelease();
}
bool includedInBindings(Store store, const MemRegion *region) const override;
/// Return the value bound to specified location in a given state.
///
/// The high level logic for this method is this:
/// getBinding (L)
/// if L has binding
/// return L's binding
/// else if L is in killset
/// return unknown
/// else
/// if L is on stack or heap
/// return undefined
/// else
/// return symbolic
SVal getBinding(Store S, Loc L, QualType T) override {
return getBinding(getRegionBindings(S), L, T);
}
std::optional<SVal> getUniqueDefaultBinding(RegionBindingsConstRef B,
const TypedValueRegion *R) const;
std::optional<SVal>
getUniqueDefaultBinding(nonloc::LazyCompoundVal LCV) const;
std::optional<SVal> getDefaultBinding(Store S, const MemRegion *R) override {
RegionBindingsRef B = getRegionBindings(S);
// Default bindings are always applied over a base region so look up the
// base region's default binding, otherwise the lookup will fail when R
// is at an offset from R->getBaseRegion().
return B.getDefaultBinding(R->getBaseRegion());
}
SVal getBinding(RegionBindingsConstRef B, Loc L, QualType T = QualType());
SVal getBindingForElement(RegionBindingsConstRef B, const ElementRegion *R);
SVal getBindingForField(RegionBindingsConstRef B, const FieldRegion *R);
SVal getBindingForObjCIvar(RegionBindingsConstRef B, const ObjCIvarRegion *R);
SVal getBindingForVar(RegionBindingsConstRef B, const VarRegion *R);
SVal getBindingForLazySymbol(const TypedValueRegion *R);
SVal getBindingForFieldOrElementCommon(RegionBindingsConstRef B,
const TypedValueRegion *R,
QualType Ty);
SVal getLazyBinding(const SubRegion *LazyBindingRegion,
RegionBindingsRef LazyBinding);
/// Get bindings for the values in a struct and return a CompoundVal, used
/// when doing struct copy:
/// struct s x, y;
/// x = y;
/// y's value is retrieved by this method.
SVal getBindingForStruct(RegionBindingsConstRef B, const TypedValueRegion *R);
SVal getBindingForArray(RegionBindingsConstRef B, const TypedValueRegion *R);
NonLoc createLazyBinding(RegionBindingsConstRef B, const TypedValueRegion *R);
/// Used to lazily generate derived symbols for bindings that are defined
/// implicitly by default bindings in a super region.
///
/// Note that callers may need to specially handle LazyCompoundVals, which
/// are returned as is in case the caller needs to treat them differently.
std::optional<SVal>
getBindingForDerivedDefaultValue(RegionBindingsConstRef B,
const MemRegion *superR,
const TypedValueRegion *R, QualType Ty);
/// Get the state and region whose binding this region \p R corresponds to.
///
/// If there is no lazy binding for \p R, the returned value will have a null
/// \c second. Note that a null pointer can represents a valid Store.
std::pair<Store, const SubRegion *>
findLazyBinding(RegionBindingsConstRef B, const SubRegion *R,
const SubRegion *originalRegion);
/// Returns the cached set of interesting SVals contained within a lazy
/// binding.
///
/// The precise value of "interesting" is determined for the purposes of
/// RegionStore's internal analysis. It must always contain all regions and
/// symbols, but may omit constants and other kinds of SVal.
///
/// In contrast to compound values, LazyCompoundVals are also added
/// to the 'interesting values' list in addition to the child interesting
/// values.
const SValListTy &getInterestingValues(nonloc::LazyCompoundVal LCV);
//===------------------------------------------------------------------===//
// State pruning.
//===------------------------------------------------------------------===//
/// removeDeadBindings - Scans the RegionStore of 'state' for dead values.
/// It returns a new Store with these values removed.
StoreRef removeDeadBindings(Store store, const StackFrameContext *LCtx,
SymbolReaper& SymReaper) override;
//===------------------------------------------------------------------===//
// Utility methods.
//===------------------------------------------------------------------===//
RegionBindingsRef getRegionBindings(Store store) const {
llvm::PointerIntPair<Store, 1, bool> Ptr;
Ptr.setFromOpaqueValue(const_cast<void *>(store));
return RegionBindingsRef(
CBFactory,
static_cast<const RegionBindings::TreeTy *>(Ptr.getPointer()),
RBFactory.getTreeFactory(),
Ptr.getInt());
}
void printJson(raw_ostream &Out, Store S, const char *NL = "\n",
unsigned int Space = 0, bool IsDot = false) const override;
void iterBindings(Store store, BindingsHandler& f) override {
RegionBindingsRef B = getRegionBindings(store);
for (const auto &[Region, Cluster] : B) {
for (const auto &[Key, Value] : Cluster) {
if (!Key.isDirect())
continue;
if (const SubRegion *R = dyn_cast<SubRegion>(Key.getRegion())) {
// FIXME: Possibly incorporate the offset?
if (!f.HandleBinding(*this, store, R, Value))
return;
}
}
}
}
};
} // end anonymous namespace
//===----------------------------------------------------------------------===//
// RegionStore creation.
//===----------------------------------------------------------------------===//
std::unique_ptr<StoreManager>
ento::CreateRegionStoreManager(ProgramStateManager &StMgr) {
return std::make_unique<RegionStoreManager>(StMgr);
}
//===----------------------------------------------------------------------===//
// Region Cluster analysis.
//===----------------------------------------------------------------------===//
namespace {
/// Used to determine which global regions are automatically included in the
/// initial worklist of a ClusterAnalysis.
enum GlobalsFilterKind {
/// Don't include any global regions.
GFK_None,
/// Only include system globals.
GFK_SystemOnly,
/// Include all global regions.
GFK_All
};
template <typename DERIVED>
class ClusterAnalysis {
protected:
typedef llvm::DenseMap<const MemRegion *, const ClusterBindings *> ClusterMap;
typedef const MemRegion * WorkListElement;
typedef SmallVector<WorkListElement, 10> WorkList;
llvm::SmallPtrSet<const ClusterBindings *, 16> Visited;
WorkList WL;
RegionStoreManager &RM;
ASTContext &Ctx;
SValBuilder &svalBuilder;
RegionBindingsRef B;
protected:
const ClusterBindings *getCluster(const MemRegion *R) {
return B.lookup(R);
}
/// Returns true if all clusters in the given memspace should be initially
/// included in the cluster analysis. Subclasses may provide their
/// own implementation.
bool includeEntireMemorySpace(const MemRegion *Base) {
return false;
}
public:
ClusterAnalysis(RegionStoreManager &rm, ProgramStateManager &StateMgr,
RegionBindingsRef b)
: RM(rm), Ctx(StateMgr.getContext()),
svalBuilder(StateMgr.getSValBuilder()), B(std::move(b)) {}
RegionBindingsRef getRegionBindings() const { return B; }
bool isVisited(const MemRegion *R) {
return Visited.count(getCluster(R));
}
void GenerateClusters() {
// Scan the entire set of bindings and record the region clusters.
for (RegionBindingsRef::iterator RI = B.begin(), RE = B.end();
RI != RE; ++RI){
const MemRegion *Base = RI.getKey();
const ClusterBindings &Cluster = RI.getData();
assert(!Cluster.isEmpty() && "Empty clusters should be removed");
static_cast<DERIVED*>(this)->VisitAddedToCluster(Base, Cluster);
// If the base's memspace should be entirely invalidated, add the cluster
// to the workspace up front.
if (static_cast<DERIVED*>(this)->includeEntireMemorySpace(Base))
AddToWorkList(WorkListElement(Base), &Cluster);
}
}
bool AddToWorkList(WorkListElement E, const ClusterBindings *C) {
if (C && !Visited.insert(C).second)
return false;
WL.push_back(E);
return true;
}
bool AddToWorkList(const MemRegion *R) {
return static_cast<DERIVED*>(this)->AddToWorkList(R);
}
void RunWorkList() {
while (!WL.empty()) {
WorkListElement E = WL.pop_back_val();
const MemRegion *BaseR = E;
static_cast<DERIVED*>(this)->VisitCluster(BaseR, getCluster(BaseR));
}
}
void VisitAddedToCluster(const MemRegion *baseR, const ClusterBindings &C) {}
void VisitCluster(const MemRegion *baseR, const ClusterBindings *C) {}
void VisitCluster(const MemRegion *BaseR, const ClusterBindings *C,
bool Flag) {
static_cast<DERIVED*>(this)->VisitCluster(BaseR, C);
}
};
}
//===----------------------------------------------------------------------===//
// Binding invalidation.
//===----------------------------------------------------------------------===//
bool RegionStoreManager::scanReachableSymbols(Store S, const MemRegion *R,
ScanReachableSymbols &Callbacks) {
assert(R == R->getBaseRegion() && "Should only be called for base regions");
RegionBindingsRef B = getRegionBindings(S);
const ClusterBindings *Cluster = B.lookup(R);
if (!Cluster)
return true;
for (ClusterBindings::iterator RI = Cluster->begin(), RE = Cluster->end();
RI != RE; ++RI) {
if (!Callbacks.scan(RI.getData()))
return false;
}
return true;
}
static inline bool isUnionField(const FieldRegion *FR) {
return FR->getDecl()->getParent()->isUnion();
}
typedef SmallVector<const FieldDecl *, 8> FieldVector;
static void getSymbolicOffsetFields(BindingKey K, FieldVector &Fields) {
assert(K.hasSymbolicOffset() && "Not implemented for concrete offset keys");
const MemRegion *Base = K.getConcreteOffsetRegion();
const MemRegion *R = K.getRegion();
while (R != Base) {
if (const FieldRegion *FR = dyn_cast<FieldRegion>(R))
if (!isUnionField(FR))
Fields.push_back(FR->getDecl());
R = cast<SubRegion>(R)->getSuperRegion();
}
}
static bool isCompatibleWithFields(BindingKey K, const FieldVector &Fields) {
assert(K.hasSymbolicOffset() && "Not implemented for concrete offset keys");
if (Fields.empty())
return true;
FieldVector FieldsInBindingKey;
getSymbolicOffsetFields(K, FieldsInBindingKey);
ptrdiff_t Delta = FieldsInBindingKey.size() - Fields.size();
if (Delta >= 0)
return std::equal(FieldsInBindingKey.begin() + Delta,
FieldsInBindingKey.end(),
Fields.begin());
else
return std::equal(FieldsInBindingKey.begin(), FieldsInBindingKey.end(),
Fields.begin() - Delta);
}
/// Collects all bindings in \p Cluster that may refer to bindings within
/// \p Top.
///
/// Each binding is a pair whose \c first is the key (a BindingKey) and whose
/// \c second is the value (an SVal).
///
/// The \p IncludeAllDefaultBindings parameter specifies whether to include
/// default bindings that may extend beyond \p Top itself, e.g. if \p Top is
/// an aggregate within a larger aggregate with a default binding.
static void
collectSubRegionBindings(SmallVectorImpl<BindingPair> &Bindings,
SValBuilder &SVB, const ClusterBindings &Cluster,
const SubRegion *Top, BindingKey TopKey,
bool IncludeAllDefaultBindings) {
FieldVector FieldsInSymbolicSubregions;
if (TopKey.hasSymbolicOffset()) {
getSymbolicOffsetFields(TopKey, FieldsInSymbolicSubregions);
Top = TopKey.getConcreteOffsetRegion();
TopKey = BindingKey::Make(Top, BindingKey::Default);
}
// Find the length (in bits) of the region being invalidated.
uint64_t Length = UINT64_MAX;
SVal Extent = Top->getMemRegionManager().getStaticSize(Top, SVB);
if (std::optional<nonloc::ConcreteInt> ExtentCI =
Extent.getAs<nonloc::ConcreteInt>()) {
const llvm::APSInt &ExtentInt = ExtentCI->getValue();
assert(ExtentInt.isNonNegative() || ExtentInt.isUnsigned());
// Extents are in bytes but region offsets are in bits. Be careful!
Length = ExtentInt.getLimitedValue() * SVB.getContext().getCharWidth();
} else if (const FieldRegion *FR = dyn_cast<FieldRegion>(Top)) {
if (FR->getDecl()->isBitField())
Length = FR->getDecl()->getBitWidthValue();
}
for (const auto &StoreEntry : Cluster) {
BindingKey NextKey = StoreEntry.first;
if (NextKey.getRegion() == TopKey.getRegion()) {
// FIXME: This doesn't catch the case where we're really invalidating a
// region with a symbolic offset. Example:
// R: points[i].y
// Next: points[0].x
if (NextKey.getOffset() > TopKey.getOffset() &&
NextKey.getOffset() - TopKey.getOffset() < Length) {
// Case 1: The next binding is inside the region we're invalidating.
// Include it.
Bindings.push_back(StoreEntry);
} else if (NextKey.getOffset() == TopKey.getOffset()) {
// Case 2: The next binding is at the same offset as the region we're
// invalidating. In this case, we need to leave default bindings alone,
// since they may be providing a default value for a regions beyond what
// we're invalidating.
// FIXME: This is probably incorrect; consider invalidating an outer
// struct whose first field is bound to a LazyCompoundVal.
if (IncludeAllDefaultBindings || NextKey.isDirect())
Bindings.push_back(StoreEntry);
}
} else if (NextKey.hasSymbolicOffset()) {
const MemRegion *Base = NextKey.getConcreteOffsetRegion();
if (Top->isSubRegionOf(Base) && Top != Base) {
// Case 3: The next key is symbolic and we just changed something within
// its concrete region. We don't know if the binding is still valid, so
// we'll be conservative and include it.
if (IncludeAllDefaultBindings || NextKey.isDirect())
if (isCompatibleWithFields(NextKey, FieldsInSymbolicSubregions))
Bindings.push_back(StoreEntry);
} else if (const SubRegion *BaseSR = dyn_cast<SubRegion>(Base)) {
// Case 4: The next key is symbolic, but we changed a known
// super-region. In this case the binding is certainly included.
if (BaseSR->isSubRegionOf(Top))
if (isCompatibleWithFields(NextKey, FieldsInSymbolicSubregions))
Bindings.push_back(StoreEntry);
}
}
}
}
static void
collectSubRegionBindings(SmallVectorImpl<BindingPair> &Bindings,
SValBuilder &SVB, const ClusterBindings &Cluster,
const SubRegion *Top, bool IncludeAllDefaultBindings) {
collectSubRegionBindings(Bindings, SVB, Cluster, Top,
BindingKey::Make(Top, BindingKey::Default),
IncludeAllDefaultBindings);
}
RegionBindingsRef
RegionStoreManager::removeSubRegionBindings(RegionBindingsConstRef B,
const SubRegion *Top) {
BindingKey TopKey = BindingKey::Make(Top, BindingKey::Default);
const MemRegion *ClusterHead = TopKey.getBaseRegion();
if (Top == ClusterHead) {
// We can remove an entire cluster's bindings all in one go.
return B.remove(Top);
}
const ClusterBindings *Cluster = B.lookup(ClusterHead);
if (!Cluster) {
// If we're invalidating a region with a symbolic offset, we need to make
// sure we don't treat the base region as uninitialized anymore.
if (TopKey.hasSymbolicOffset()) {
const SubRegion *Concrete = TopKey.getConcreteOffsetRegion();
return B.addBinding(Concrete, BindingKey::Default, UnknownVal());
}
return B;
}
SmallVector<BindingPair, 32> Bindings;
collectSubRegionBindings(Bindings, svalBuilder, *Cluster, Top, TopKey,
/*IncludeAllDefaultBindings=*/false);
ClusterBindingsRef Result(*Cluster, CBFactory);
for (BindingKey Key : llvm::make_first_range(Bindings))
Result = Result.remove(Key);
// If we're invalidating a region with a symbolic offset, we need to make sure
// we don't treat the base region as uninitialized anymore.
// FIXME: This isn't very precise; see the example in
// collectSubRegionBindings.
if (TopKey.hasSymbolicOffset()) {
const SubRegion *Concrete = TopKey.getConcreteOffsetRegion();
Result = Result.add(BindingKey::Make(Concrete, BindingKey::Default),
UnknownVal());
}
if (Result.isEmpty())
return B.remove(ClusterHead);
return B.add(ClusterHead, Result.asImmutableMap());
}
namespace {
class InvalidateRegionsWorker : public ClusterAnalysis<InvalidateRegionsWorker>
{
const Stmt *S;
unsigned Count;
const LocationContext *LCtx;
InvalidatedSymbols &IS;
RegionAndSymbolInvalidationTraits &ITraits;
StoreManager::InvalidatedRegions *Regions;
GlobalsFilterKind GlobalsFilter;
public:
InvalidateRegionsWorker(RegionStoreManager &rm, ProgramStateManager &stateMgr,
RegionBindingsRef b, const Stmt *S, unsigned count,
const LocationContext *lctx, InvalidatedSymbols &is,
RegionAndSymbolInvalidationTraits &ITraitsIn,
StoreManager::InvalidatedRegions *r,
GlobalsFilterKind GFK)
: ClusterAnalysis<InvalidateRegionsWorker>(rm, stateMgr, b), S(S),
Count(count), LCtx(lctx), IS(is), ITraits(ITraitsIn), Regions(r),
GlobalsFilter(GFK) {}
void VisitCluster(const MemRegion *baseR, const ClusterBindings *C);
void VisitBinding(SVal V);
using ClusterAnalysis::AddToWorkList;
bool AddToWorkList(const MemRegion *R);
/// Returns true if all clusters in the memory space for \p Base should be
/// be invalidated.
bool includeEntireMemorySpace(const MemRegion *Base);
/// Returns true if the memory space of the given region is one of the global
/// regions specially included at the start of invalidation.
bool isInitiallyIncludedGlobalRegion(const MemRegion *R);
};
}
bool InvalidateRegionsWorker::AddToWorkList(const MemRegion *R) {
bool doNotInvalidateSuperRegion = ITraits.hasTrait(
R, RegionAndSymbolInvalidationTraits::TK_DoNotInvalidateSuperRegion);
const MemRegion *BaseR = doNotInvalidateSuperRegion ? R : R->getBaseRegion();
return AddToWorkList(WorkListElement(BaseR), getCluster(BaseR));
}
void InvalidateRegionsWorker::VisitBinding(SVal V) {
// A symbol? Mark it touched by the invalidation.
if (SymbolRef Sym = V.getAsSymbol())
IS.insert(Sym);
if (const MemRegion *R = V.getAsRegion()) {
AddToWorkList(R);
return;
}
// Is it a LazyCompoundVal? All references get invalidated as well.
if (std::optional<nonloc::LazyCompoundVal> LCS =
V.getAs<nonloc::LazyCompoundVal>()) {
// `getInterestingValues()` returns SVals contained within LazyCompoundVals,
// so there is no need to visit them.
for (SVal V : RM.getInterestingValues(*LCS))
if (!isa<nonloc::LazyCompoundVal>(V))
VisitBinding(V);
return;
}
}
void InvalidateRegionsWorker::VisitCluster(const MemRegion *baseR,
const ClusterBindings *C) {
bool PreserveRegionsContents =
ITraits.hasTrait(baseR,
RegionAndSymbolInvalidationTraits::TK_PreserveContents);
if (C) {
for (SVal Val : llvm::make_second_range(*C))
VisitBinding(Val);
// Invalidate regions contents.
if (!PreserveRegionsContents)
B = B.remove(baseR);
}
if (const auto *TO = dyn_cast<TypedValueRegion>(baseR)) {
if (const auto *RD = TO->getValueType()->getAsCXXRecordDecl()) {
// Lambdas can affect all static local variables without explicitly
// capturing those.
// We invalidate all static locals referenced inside the lambda body.
if (RD->isLambda() && RD->getLambdaCallOperator()->getBody()) {
using namespace ast_matchers;
const char *DeclBind = "DeclBind";
StatementMatcher RefToStatic = stmt(hasDescendant(declRefExpr(
to(varDecl(hasStaticStorageDuration()).bind(DeclBind)))));
auto Matches =
match(RefToStatic, *RD->getLambdaCallOperator()->getBody(),
RD->getASTContext());
for (BoundNodes &Match : Matches) {
auto *VD = Match.getNodeAs<VarDecl>(DeclBind);
const VarRegion *ToInvalidate =
RM.getRegionManager().getVarRegion(VD, LCtx);
AddToWorkList(ToInvalidate);
}
}
}
}
// BlockDataRegion? If so, invalidate captured variables that are passed
// by reference.
if (const BlockDataRegion *BR = dyn_cast<BlockDataRegion>(baseR)) {
for (auto Var : BR->referenced_vars()) {
const VarRegion *VR = Var.getCapturedRegion();
const VarDecl *VD = VR->getDecl();
if (VD->hasAttr<BlocksAttr>() || !VD->hasLocalStorage()) {
AddToWorkList(VR);
}
else if (Loc::isLocType(VR->getValueType())) {
// Map the current bindings to a Store to retrieve the value
// of the binding. If that binding itself is a region, we should
// invalidate that region. This is because a block may capture
// a pointer value, but the thing pointed by that pointer may
// get invalidated.
SVal V = RM.getBinding(B, loc::MemRegionVal(VR));
if (std::optional<Loc> L = V.getAs<Loc>()) {
if (const MemRegion *LR = L->getAsRegion())
AddToWorkList(LR);
}
}
}
return;
}
// Symbolic region?
if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(baseR))
IS.insert(SR->getSymbol());
// Nothing else should be done in the case when we preserve regions context.
if (PreserveRegionsContents)
return;
// Otherwise, we have a normal data region. Record that we touched the region.
if (Regions)
Regions->push_back(baseR);
if (isa<AllocaRegion, SymbolicRegion>(baseR)) {
// Invalidate the region by setting its default value to
// conjured symbol. The type of the symbol is irrelevant.
DefinedOrUnknownSVal V =
svalBuilder.conjureSymbolVal(baseR, S, LCtx, Ctx.IntTy, Count);
B = B.addBinding(baseR, BindingKey::Default, V);
return;
}
if (!baseR->isBoundable())
return;
const TypedValueRegion *TR = cast<TypedValueRegion>(baseR);
QualType T = TR->getValueType();
if (isInitiallyIncludedGlobalRegion(baseR)) {
// If the region is a global and we are invalidating all globals,
// erasing the entry is good enough. This causes all globals to be lazily
// symbolicated from the same base symbol.
return;
}
if (T->isRecordType()) {
// Invalidate the region by setting its default value to
// conjured symbol. The type of the symbol is irrelevant.
DefinedOrUnknownSVal V =
svalBuilder.conjureSymbolVal(baseR, S, LCtx, Ctx.IntTy, Count);
B = B.addBinding(baseR, BindingKey::Default, V);
return;
}
if (const ArrayType *AT = Ctx.getAsArrayType(T)) {
bool doNotInvalidateSuperRegion = ITraits.hasTrait(
baseR,
RegionAndSymbolInvalidationTraits::TK_DoNotInvalidateSuperRegion);
if (doNotInvalidateSuperRegion) {
// We are not doing blank invalidation of the whole array region so we
// have to manually invalidate each elements.
std::optional<uint64_t> NumElements;
// Compute lower and upper offsets for region within array.
if (const ConstantArrayType *CAT = dyn_cast<ConstantArrayType>(AT))
NumElements = CAT->getZExtSize();
if (!NumElements) // We are not dealing with a constant size array
goto conjure_default;
QualType ElementTy = AT->getElementType();
uint64_t ElemSize = Ctx.getTypeSize(ElementTy);
const RegionOffset &RO = baseR->getAsOffset();
const MemRegion *SuperR = baseR->getBaseRegion();
if (RO.hasSymbolicOffset()) {
// If base region has a symbolic offset,
// we revert to invalidating the super region.
if (SuperR)
AddToWorkList(SuperR);
goto conjure_default;
}
uint64_t LowerOffset = RO.getOffset();
uint64_t UpperOffset = LowerOffset + *NumElements * ElemSize;
bool UpperOverflow = UpperOffset < LowerOffset;
// Invalidate regions which are within array boundaries,
// or have a symbolic offset.
if (!SuperR)
goto conjure_default;
const ClusterBindings *C = B.lookup(SuperR);
if (!C)
goto conjure_default;
for (const auto &[BK, V] : *C) {
std::optional<uint64_t> ROffset =
BK.hasSymbolicOffset() ? std::optional<uint64_t>() : BK.getOffset();
// Check offset is not symbolic and within array's boundaries.
// Handles arrays of 0 elements and of 0-sized elements as well.
if (!ROffset ||
((*ROffset >= LowerOffset && *ROffset < UpperOffset) ||
(UpperOverflow &&
(*ROffset >= LowerOffset || *ROffset < UpperOffset)) ||
(LowerOffset == UpperOffset && *ROffset == LowerOffset))) {
B = B.removeBinding(BK);
// Bound symbolic regions need to be invalidated for dead symbol
// detection.
const MemRegion *R = V.getAsRegion();
if (isa_and_nonnull<SymbolicRegion>(R))
VisitBinding(V);
}
}
}
conjure_default:
// Set the default value of the array to conjured symbol.
DefinedOrUnknownSVal V = svalBuilder.conjureSymbolVal(
baseR, S, LCtx, AT->getElementType(), Count);
B = B.addBinding(baseR, BindingKey::Default, V);
return;
}
DefinedOrUnknownSVal V =
svalBuilder.conjureSymbolVal(baseR, S, LCtx, T, Count);
assert(SymbolManager::canSymbolicate(T) || V.isUnknown());
B = B.addBinding(baseR, BindingKey::Direct, V);
}
bool InvalidateRegionsWorker::isInitiallyIncludedGlobalRegion(
const MemRegion *R) {
switch (GlobalsFilter) {
case GFK_None:
return false;
case GFK_SystemOnly:
return isa<GlobalSystemSpaceRegion>(R->getRawMemorySpace());
case GFK_All:
return isa<NonStaticGlobalSpaceRegion>(R->getRawMemorySpace());
}
llvm_unreachable("unknown globals filter");
}
bool InvalidateRegionsWorker::includeEntireMemorySpace(const MemRegion *Base) {
if (isInitiallyIncludedGlobalRegion(Base))
return true;
const MemSpaceRegion *MemSpace = Base->getRawMemorySpace();
return ITraits.hasTrait(MemSpace,
RegionAndSymbolInvalidationTraits::TK_EntireMemSpace);
}
RegionBindingsRef RegionStoreManager::invalidateGlobalRegion(
MemRegion::Kind K, const Stmt *S, unsigned Count,
const LocationContext *LCtx, RegionBindingsRef B,
InvalidatedRegions *Invalidated) {
// Bind the globals memory space to a new symbol that we will use to derive
// the bindings for all globals.
const GlobalsSpaceRegion *GS = MRMgr.getGlobalsRegion(K);
SVal V =
svalBuilder.conjureSymbolVal(/* symbolTag = */ (const void *)GS, S, LCtx,
/* type does not matter */ Ctx.IntTy, Count);
B = B.removeBinding(GS)
.addBinding(BindingKey::Make(GS, BindingKey::Default), V);
// Even if there are no bindings in the global scope, we still need to
// record that we touched it.
if (Invalidated)
Invalidated->push_back(GS);
return B;
}
void RegionStoreManager::populateWorkList(InvalidateRegionsWorker &W,
ArrayRef<SVal> Values,
InvalidatedRegions *TopLevelRegions) {
for (SVal V : Values) {
if (auto LCS = V.getAs<nonloc::LazyCompoundVal>()) {
for (SVal S : getInterestingValues(*LCS))
if (const MemRegion *R = S.getAsRegion())
W.AddToWorkList(R);
continue;
}
if (const MemRegion *R = V.getAsRegion()) {
if (TopLevelRegions)
TopLevelRegions->push_back(R);
W.AddToWorkList(R);
continue;
}
}
}
StoreRef RegionStoreManager::invalidateRegions(
Store store, ArrayRef<SVal> Values, const Stmt *S, unsigned Count,
const LocationContext *LCtx, const CallEvent *Call, InvalidatedSymbols &IS,
RegionAndSymbolInvalidationTraits &ITraits,
InvalidatedRegions *TopLevelRegions, InvalidatedRegions *Invalidated) {
GlobalsFilterKind GlobalsFilter;
if (Call) {
if (Call->isInSystemHeader())
GlobalsFilter = GFK_SystemOnly;
else
GlobalsFilter = GFK_All;
} else {
GlobalsFilter = GFK_None;
}
RegionBindingsRef B = getRegionBindings(store);
InvalidateRegionsWorker W(*this, StateMgr, B, S, Count, LCtx, IS, ITraits,
Invalidated, GlobalsFilter);
// Scan the bindings and generate the clusters.
W.GenerateClusters();
// Add the regions to the worklist.
populateWorkList(W, Values, TopLevelRegions);
W.RunWorkList();
// Return the new bindings.
B = W.getRegionBindings();
// For calls, determine which global regions should be invalidated and
// invalidate them. (Note that function-static and immutable globals are never
// invalidated by this.)
// TODO: This could possibly be more precise with modules.
switch (GlobalsFilter) {
case GFK_All:
B = invalidateGlobalRegion(MemRegion::GlobalInternalSpaceRegionKind, S,
Count, LCtx, B, Invalidated);
[[fallthrough]];
case GFK_SystemOnly:
B = invalidateGlobalRegion(MemRegion::GlobalSystemSpaceRegionKind, S, Count,
LCtx, B, Invalidated);
[[fallthrough]];
case GFK_None:
break;
}
return StoreRef(B.asStore(), *this);
}
//===----------------------------------------------------------------------===//
// Location and region casting.
//===----------------------------------------------------------------------===//
/// ArrayToPointer - Emulates the "decay" of an array to a pointer
/// type. 'Array' represents the lvalue of the array being decayed
/// to a pointer, and the returned SVal represents the decayed
/// version of that lvalue (i.e., a pointer to the first element of
/// the array). This is called by ExprEngine when evaluating casts
/// from arrays to pointers.
SVal RegionStoreManager::ArrayToPointer(Loc Array, QualType T) {
if (isa<loc::ConcreteInt>(Array))
return Array;
if (!isa<loc::MemRegionVal>(Array))
return UnknownVal();
const SubRegion *R =
cast<SubRegion>(Array.castAs<loc::MemRegionVal>().getRegion());
NonLoc ZeroIdx = svalBuilder.makeZeroArrayIndex();
return loc::MemRegionVal(MRMgr.getElementRegion(T, ZeroIdx, R, Ctx));
}
//===----------------------------------------------------------------------===//
// Loading values from regions.
//===----------------------------------------------------------------------===//
SVal RegionStoreManager::getBinding(RegionBindingsConstRef B, Loc L, QualType T) {
assert(!isa<UnknownVal>(L) && "location unknown");
assert(!isa<UndefinedVal>(L) && "location undefined");
// For access to concrete addresses, return UnknownVal. Checks
// for null dereferences (and similar errors) are done by checkers, not
// the Store.
// FIXME: We can consider lazily symbolicating such memory, but we really
// should defer this when we can reason easily about symbolicating arrays
// of bytes.
if (L.getAs<loc::ConcreteInt>()) {
return UnknownVal();
}
if (!L.getAs<loc::MemRegionVal>()) {
return UnknownVal();
}
const MemRegion *MR = L.castAs<loc::MemRegionVal>().getRegion();
if (isa<BlockDataRegion>(MR)) {
return UnknownVal();
}
// Auto-detect the binding type.
if (T.isNull()) {
if (const auto *TVR = dyn_cast<TypedValueRegion>(MR))
T = TVR->getValueType();
else if (const auto *TR = dyn_cast<TypedRegion>(MR))
T = TR->getLocationType()->getPointeeType();
else if (const auto *SR = dyn_cast<SymbolicRegion>(MR))
T = SR->getPointeeStaticType();
}
assert(!T.isNull() && "Unable to auto-detect binding type!");
assert(!T->isVoidType() && "Attempting to dereference a void pointer!");
if (!isa<TypedValueRegion>(MR))
MR = GetElementZeroRegion(cast<SubRegion>(MR), T);
// FIXME: Perhaps this method should just take a 'const MemRegion*' argument
// instead of 'Loc', and have the other Loc cases handled at a higher level.
const TypedValueRegion *R = cast<TypedValueRegion>(MR);
QualType RTy = R->getValueType();
// FIXME: we do not yet model the parts of a complex type, so treat the
// whole thing as "unknown".
if (RTy->isAnyComplexType())
return UnknownVal();
// FIXME: We should eventually handle funny addressing. e.g.:
//
// int x = ...;
// int *p = &x;
// char *q = (char*) p;
// char c = *q; // returns the first byte of 'x'.
//
// Such funny addressing will occur due to layering of regions.
if (RTy->isStructureOrClassType())
return getBindingForStruct(B, R);
// FIXME: Handle unions.
if (RTy->isUnionType())
return createLazyBinding(B, R);
if (RTy->isArrayType()) {
if (RTy->isConstantArrayType())
return getBindingForArray(B, R);
else
return UnknownVal();
}
// FIXME: handle Vector types.
if (RTy->isVectorType())
return UnknownVal();
if (const FieldRegion* FR = dyn_cast<FieldRegion>(R))
return svalBuilder.evalCast(getBindingForField(B, FR), T, QualType{});
if (const ElementRegion* ER = dyn_cast<ElementRegion>(R)) {
// FIXME: Here we actually perform an implicit conversion from the loaded
// value to the element type. Eventually we want to compose these values
// more intelligently. For example, an 'element' can encompass multiple
// bound regions (e.g., several bound bytes), or could be a subset of
// a larger value.
return svalBuilder.evalCast(getBindingForElement(B, ER), T, QualType{});
}
if (const ObjCIvarRegion *IVR = dyn_cast<ObjCIvarRegion>(R)) {
// FIXME: Here we actually perform an implicit conversion from the loaded
// value to the ivar type. What we should model is stores to ivars
// that blow past the extent of the ivar. If the address of the ivar is
// reinterpretted, it is possible we stored a different value that could
// fit within the ivar. Either we need to cast these when storing them
// or reinterpret them lazily (as we do here).
return svalBuilder.evalCast(getBindingForObjCIvar(B, IVR), T, QualType{});
}
if (const VarRegion *VR = dyn_cast<VarRegion>(R)) {
// FIXME: Here we actually perform an implicit conversion from the loaded
// value to the variable type. What we should model is stores to variables
// that blow past the extent of the variable. If the address of the
// variable is reinterpretted, it is possible we stored a different value
// that could fit within the variable. Either we need to cast these when
// storing them or reinterpret them lazily (as we do here).
return svalBuilder.evalCast(getBindingForVar(B, VR), T, QualType{});
}
const SVal *V = B.lookup(R, BindingKey::Direct);
// Check if the region has a binding.
if (V)
return *V;
// The location does not have a bound value. This means that it has
// the value it had upon its creation and/or entry to the analyzed
// function/method. These are either symbolic values or 'undefined'.
if (isa<StackLocalsSpaceRegion>(R->getRawMemorySpace())) {
// All stack variables are considered to have undefined values
// upon creation. All heap allocated blocks are considered to
// have undefined values as well unless they are explicitly bound
// to specific values.
return UndefinedVal();
}
// All other values are symbolic.
return svalBuilder.getRegionValueSymbolVal(R);
}
static QualType getUnderlyingType(const SubRegion *R) {
QualType RegionTy;
if (const TypedValueRegion *TVR = dyn_cast<TypedValueRegion>(R))
RegionTy = TVR->getValueType();
if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R))
RegionTy = SR->getSymbol()->getType();
return RegionTy;
}
/// Checks to see if store \p B has a lazy binding for region \p R.
///
/// If \p AllowSubregionBindings is \c false, a lazy binding will be rejected
/// if there are additional bindings within \p R.
///
/// Note that unlike RegionStoreManager::findLazyBinding, this will not search
/// for lazy bindings for super-regions of \p R.
static std::optional<nonloc::LazyCompoundVal>
getExistingLazyBinding(SValBuilder &SVB, RegionBindingsConstRef B,
const SubRegion *R, bool AllowSubregionBindings) {
std::optional<SVal> V = B.getDefaultBinding(R);
if (!V)
return std::nullopt;
std::optional<nonloc::LazyCompoundVal> LCV =
V->getAs<nonloc::LazyCompoundVal>();
if (!LCV)
return std::nullopt;
// If the LCV is for a subregion, the types might not match, and we shouldn't
// reuse the binding.
QualType RegionTy = getUnderlyingType(R);
if (!RegionTy.isNull() &&
!RegionTy->isVoidPointerType()) {
QualType SourceRegionTy = LCV->getRegion()->getValueType();
if (!SVB.getContext().hasSameUnqualifiedType(RegionTy, SourceRegionTy))
return std::nullopt;
}
if (!AllowSubregionBindings) {
// If there are any other bindings within this region, we shouldn't reuse
// the top-level binding.
SmallVector<BindingPair, 16> Bindings;
collectSubRegionBindings(Bindings, SVB, *B.lookup(R->getBaseRegion()), R,
/*IncludeAllDefaultBindings=*/true);
if (Bindings.size() > 1)
return std::nullopt;
}
return *LCV;
}
std::pair<Store, const SubRegion *>
RegionStoreManager::findLazyBinding(RegionBindingsConstRef B,
const SubRegion *R,
const SubRegion *originalRegion) {
if (originalRegion != R) {
if (std::optional<nonloc::LazyCompoundVal> V =
getExistingLazyBinding(svalBuilder, B, R, true))
return std::make_pair(V->getStore(), V->getRegion());
}
typedef std::pair<Store, const SubRegion *> StoreRegionPair;
StoreRegionPair Result = StoreRegionPair();
if (const ElementRegion *ER = dyn_cast<ElementRegion>(R)) {
Result = findLazyBinding(B, cast<SubRegion>(ER->getSuperRegion()),
originalRegion);
if (Result.second)
Result.second = MRMgr.getElementRegionWithSuper(ER, Result.second);
} else if (const FieldRegion *FR = dyn_cast<FieldRegion>(R)) {
Result = findLazyBinding(B, cast<SubRegion>(FR->getSuperRegion()),
originalRegion);
if (Result.second)
Result.second = MRMgr.getFieldRegionWithSuper(FR, Result.second);
} else if (const CXXBaseObjectRegion *BaseReg =
dyn_cast<CXXBaseObjectRegion>(R)) {
// C++ base object region is another kind of region that we should blast
// through to look for lazy compound value. It is like a field region.
Result = findLazyBinding(B, cast<SubRegion>(BaseReg->getSuperRegion()),
originalRegion);
if (Result.second)
Result.second = MRMgr.getCXXBaseObjectRegionWithSuper(BaseReg,
Result.second);
}
return Result;
}
/// This is a helper function for `getConstantValFromConstArrayInitializer`.
///
/// Return an array of extents of the declared array type.
///
/// E.g. for `int x[1][2][3];` returns { 1, 2, 3 }.
static SmallVector<uint64_t, 2>
getConstantArrayExtents(const ConstantArrayType *CAT) {
assert(CAT && "ConstantArrayType should not be null");
CAT = cast<ConstantArrayType>(CAT->getCanonicalTypeInternal());
SmallVector<uint64_t, 2> Extents;
do {
Extents.push_back(CAT->getZExtSize());
} while ((CAT = dyn_cast<ConstantArrayType>(CAT->getElementType())));
return Extents;
}
/// This is a helper function for `getConstantValFromConstArrayInitializer`.
///
/// Return an array of offsets from nested ElementRegions and a root base
/// region. The array is never empty and a base region is never null.
///
/// E.g. for `Element{Element{Element{VarRegion},1},2},3}` returns { 3, 2, 1 }.
/// This represents an access through indirection: `arr[1][2][3];`
///
/// \param ER The given (possibly nested) ElementRegion.
///
/// \note The result array is in the reverse order of indirection expression:
/// arr[1][2][3] -> { 3, 2, 1 }. This helps to provide complexity O(n), where n
/// is a number of indirections. It may not affect performance in real-life
/// code, though.
static std::pair<SmallVector<SVal, 2>, const MemRegion *>
getElementRegionOffsetsWithBase(const ElementRegion *ER) {
assert(ER && "ConstantArrayType should not be null");
const MemRegion *Base;
SmallVector<SVal, 2> SValOffsets;
do {
SValOffsets.push_back(ER->getIndex());
Base = ER->getSuperRegion();
ER = dyn_cast<ElementRegion>(Base);
} while (ER);
return {SValOffsets, Base};
}
/// This is a helper function for `getConstantValFromConstArrayInitializer`.
///
/// Convert array of offsets from `SVal` to `uint64_t` in consideration of
/// respective array extents.
/// \param SrcOffsets [in] The array of offsets of type `SVal` in reversed
/// order (expectedly received from `getElementRegionOffsetsWithBase`).
/// \param ArrayExtents [in] The array of extents.
/// \param DstOffsets [out] The array of offsets of type `uint64_t`.
/// \returns:
/// - `std::nullopt` for successful convertion.
/// - `UndefinedVal` or `UnknownVal` otherwise. It's expected that this SVal
/// will be returned as a suitable value of the access operation.
/// which should be returned as a correct
///
/// \example:
/// const int arr[10][20][30] = {}; // ArrayExtents { 10, 20, 30 }
/// int x1 = arr[4][5][6]; // SrcOffsets { NonLoc(6), NonLoc(5), NonLoc(4) }
/// // DstOffsets { 4, 5, 6 }
/// // returns std::nullopt
/// int x2 = arr[42][5][-6]; // returns UndefinedVal
/// int x3 = arr[4][5][x2]; // returns UnknownVal
static std::optional<SVal>
convertOffsetsFromSvalToUnsigneds(const SmallVector<SVal, 2> &SrcOffsets,
const SmallVector<uint64_t, 2> ArrayExtents,
SmallVector<uint64_t, 2> &DstOffsets) {
// Check offsets for being out of bounds.
// C++20 [expr.add] 7.6.6.4 (excerpt):
// If P points to an array element i of an array object x with n
// elements, where i < 0 or i > n, the behavior is undefined.
// Dereferencing is not allowed on the "one past the last
// element", when i == n.
// Example:
// const int arr[3][2] = {{1, 2}, {3, 4}};
// arr[0][0]; // 1
// arr[0][1]; // 2
// arr[0][2]; // UB
// arr[1][0]; // 3
// arr[1][1]; // 4
// arr[1][-1]; // UB
// arr[2][0]; // 0
// arr[2][1]; // 0
// arr[-2][0]; // UB
DstOffsets.resize(SrcOffsets.size());
auto ExtentIt = ArrayExtents.begin();
auto OffsetIt = DstOffsets.begin();
// Reverse `SValOffsets` to make it consistent with `ArrayExtents`.
for (SVal V : llvm::reverse(SrcOffsets)) {
if (auto CI = V.getAs<nonloc::ConcreteInt>()) {
// When offset is out of array's bounds, result is UB.
const llvm::APSInt &Offset = CI->getValue();
if (Offset.isNegative() || Offset.uge(*(ExtentIt++)))
return UndefinedVal();
// Store index in a reversive order.
*(OffsetIt++) = Offset.getZExtValue();
continue;
}
// Symbolic index presented. Return Unknown value.
// FIXME: We also need to take ElementRegions with symbolic indexes into
// account.
return UnknownVal();
}
return std::nullopt;
}
std::optional<SVal> RegionStoreManager::getConstantValFromConstArrayInitializer(
RegionBindingsConstRef B, const ElementRegion *R) {
assert(R && "ElementRegion should not be null");
// Treat an n-dimensional array.
SmallVector<SVal, 2> SValOffsets;
const MemRegion *Base;
std::tie(SValOffsets, Base) = getElementRegionOffsetsWithBase(R);
const VarRegion *VR = dyn_cast<VarRegion>(Base);
if (!VR)
return std::nullopt;
assert(!SValOffsets.empty() && "getElementRegionOffsets guarantees the "
"offsets vector is not empty.");
// Check if the containing array has an initialized value that we can trust.
// We can trust a const value or a value of a global initializer in main().
const VarDecl *VD = VR->getDecl();
if (!VD->getType().isConstQualified() &&
!R->getElementType().isConstQualified() &&
(!B.isMainAnalysis() || !VD->hasGlobalStorage()))
return std::nullopt;
// Array's declaration should have `ConstantArrayType` type, because only this
// type contains an array extent. It may happen that array type can be of
// `IncompleteArrayType` type. To get the declaration of `ConstantArrayType`
// type, we should find the declaration in the redeclarations chain that has
// the initialization expression.
// NOTE: `getAnyInitializer` has an out-parameter, which returns a new `VD`
// from which an initializer is obtained. We replace current `VD` with the new
// `VD`. If the return value of the function is null than `VD` won't be
// replaced.
const Expr *Init = VD->getAnyInitializer(VD);
// NOTE: If `Init` is non-null, then a new `VD` is non-null for sure. So check
// `Init` for null only and don't worry about the replaced `VD`.
if (!Init)
return std::nullopt;
// Array's declaration should have ConstantArrayType type, because only this
// type contains an array extent.
const ConstantArrayType *CAT = Ctx.getAsConstantArrayType(VD->getType());
if (!CAT)
return std::nullopt;
// Get array extents.
SmallVector<uint64_t, 2> Extents = getConstantArrayExtents(CAT);
// The number of offsets should equal to the numbers of extents,
// otherwise wrong type punning occurred. For instance:
// int arr[1][2][3];
// auto ptr = (int(*)[42])arr;
// auto x = ptr[4][2]; // UB
// FIXME: Should return UndefinedVal.
if (SValOffsets.size() != Extents.size())
return std::nullopt;
SmallVector<uint64_t, 2> ConcreteOffsets;
if (std::optional<SVal> V = convertOffsetsFromSvalToUnsigneds(
SValOffsets, Extents, ConcreteOffsets))
return *V;
// Handle InitListExpr.
// Example:
// const char arr[4][2] = { { 1, 2 }, { 3 }, 4, 5 };
if (const auto *ILE = dyn_cast<InitListExpr>(Init))
return getSValFromInitListExpr(ILE, ConcreteOffsets, R->getElementType());
// Handle StringLiteral.
// Example:
// const char arr[] = "abc";
if (const auto *SL = dyn_cast<StringLiteral>(Init))
return getSValFromStringLiteral(SL, ConcreteOffsets.front(),
R->getElementType());
// FIXME: Handle CompoundLiteralExpr.
return std::nullopt;
}
/// Returns an SVal, if possible, for the specified position of an
/// initialization list.
///
/// \param ILE The given initialization list.
/// \param Offsets The array of unsigned offsets. E.g. for the expression
/// `int x = arr[1][2][3];` an array should be { 1, 2, 3 }.
/// \param ElemT The type of the result SVal expression.
/// \return Optional SVal for the particular position in the initialization
/// list. E.g. for the list `{{1, 2},[3, 4],{5, 6}, {}}` offsets:
/// - {1, 1} returns SVal{4}, because it's the second position in the second
/// sublist;
/// - {3, 0} returns SVal{0}, because there's no explicit value at this
/// position in the sublist.
///
/// NOTE: Inorder to get a valid SVal, a caller shall guarantee valid offsets
/// for the given initialization list. Otherwise SVal can be an equivalent to 0
/// or lead to assertion.
std::optional<SVal> RegionStoreManager::getSValFromInitListExpr(
const InitListExpr *ILE, const SmallVector<uint64_t, 2> &Offsets,
QualType ElemT) {
assert(ILE && "InitListExpr should not be null");
for (uint64_t Offset : Offsets) {
// C++20 [dcl.init.string] 9.4.2.1:
// An array of ordinary character type [...] can be initialized by [...]
// an appropriately-typed string-literal enclosed in braces.
// Example:
// const char arr[] = { "abc" };
if (ILE->isStringLiteralInit())
if (const auto *SL = dyn_cast<StringLiteral>(ILE->getInit(0)))
return getSValFromStringLiteral(SL, Offset, ElemT);
// C++20 [expr.add] 9.4.17.5 (excerpt):
// i-th array element is value-initialized for each k < i ≤ n,
// where k is an expression-list size and n is an array extent.
if (Offset >= ILE->getNumInits())
return svalBuilder.makeZeroVal(ElemT);
const Expr *E = ILE->getInit(Offset);
const auto *IL = dyn_cast<InitListExpr>(E);
if (!IL)
// Return a constant value, if it is presented.
// FIXME: Support other SVals.
return svalBuilder.getConstantVal(E);
// Go to the nested initializer list.
ILE = IL;
}
assert(ILE);
// FIXME: Unhandeled InitListExpr sub-expression, possibly constructing an
// enum?
return std::nullopt;
}
/// Returns an SVal, if possible, for the specified position in a string
/// literal.
///
/// \param SL The given string literal.
/// \param Offset The unsigned offset. E.g. for the expression
/// `char x = str[42];` an offset should be 42.
/// E.g. for the string "abc" offset:
/// - 1 returns SVal{b}, because it's the second position in the string.
/// - 42 returns SVal{0}, because there's no explicit value at this
/// position in the string.
/// \param ElemT The type of the result SVal expression.
///
/// NOTE: We return `0` for every offset >= the literal length for array
/// declarations, like:
/// const char str[42] = "123"; // Literal length is 4.
/// char c = str[41]; // Offset is 41.
/// FIXME: Nevertheless, we can't do the same for pointer declaraions, like:
/// const char * const str = "123"; // Literal length is 4.
/// char c = str[41]; // Offset is 41. Returns `0`, but Undef
/// // expected.
/// It should be properly handled before reaching this point.
/// The main problem is that we can't distinguish between these declarations,
/// because in case of array we can get the Decl from VarRegion, but in case
/// of pointer the region is a StringRegion, which doesn't contain a Decl.
/// Possible solution could be passing an array extent along with the offset.
SVal RegionStoreManager::getSValFromStringLiteral(const StringLiteral *SL,
uint64_t Offset,
QualType ElemT) {
assert(SL && "StringLiteral should not be null");
// C++20 [dcl.init.string] 9.4.2.3:
// If there are fewer initializers than there are array elements, each
// element not explicitly initialized shall be zero-initialized [dcl.init].
uint32_t Code = (Offset >= SL->getLength()) ? 0 : SL->getCodeUnit(Offset);
return svalBuilder.makeIntVal(Code, ElemT);
}
static std::optional<SVal> getDerivedSymbolForBinding(
RegionBindingsConstRef B, const TypedValueRegion *BaseRegion,
const TypedValueRegion *SubReg, const ASTContext &Ctx, SValBuilder &SVB) {
assert(BaseRegion);
QualType BaseTy = BaseRegion->getValueType();
QualType Ty = SubReg->getValueType();
if (BaseTy->isScalarType() && Ty->isScalarType()) {
if (Ctx.getTypeSizeInChars(BaseTy) >= Ctx.getTypeSizeInChars(Ty)) {
if (const std::optional<SVal> &ParentValue =
B.getDirectBinding(BaseRegion)) {
if (SymbolRef ParentValueAsSym = ParentValue->getAsSymbol())
return SVB.getDerivedRegionValueSymbolVal(ParentValueAsSym, SubReg);
if (ParentValue->isUndef())
return UndefinedVal();
// Other cases: give up. We are indexing into a larger object
// that has some value, but we don't know how to handle that yet.
return UnknownVal();
}
}
}
return std::nullopt;
}
SVal RegionStoreManager::getBindingForElement(RegionBindingsConstRef B,
const ElementRegion* R) {
// Check if the region has a binding.
if (const std::optional<SVal> &V = B.getDirectBinding(R))
return *V;
const MemRegion* superR = R->getSuperRegion();
// Check if the region is an element region of a string literal.
if (const StringRegion *StrR = dyn_cast<StringRegion>(superR)) {
// FIXME: Handle loads from strings where the literal is treated as
// an integer, e.g., *((unsigned int*)"hello"). Such loads are UB according
// to C++20 7.2.1.11 [basic.lval].
QualType T = Ctx.getAsArrayType(StrR->getValueType())->getElementType();
if (!Ctx.hasSameUnqualifiedType(T, R->getElementType()))
return UnknownVal();
if (const auto CI = R->getIndex().getAs<nonloc::ConcreteInt>()) {
const llvm::APSInt &Idx = CI->getValue();
if (Idx < 0)
return UndefinedVal();
const StringLiteral *SL = StrR->getStringLiteral();
return getSValFromStringLiteral(SL, Idx.getZExtValue(), T);
}
} else if (isa<ElementRegion, VarRegion>(superR)) {
if (std::optional<SVal> V = getConstantValFromConstArrayInitializer(B, R))
return *V;
}
// Check for loads from a code text region. For such loads, just give up.
if (isa<CodeTextRegion>(superR))
return UnknownVal();
// Handle the case where we are indexing into a larger scalar object.
// For example, this handles:
// int x = ...
// char *y = &x;
// return *y;
// FIXME: This is a hack, and doesn't do anything really intelligent yet.
const RegionRawOffset &O = R->getAsArrayOffset();
// If we cannot reason about the offset, return an unknown value.
if (!O.getRegion())
return UnknownVal();
if (const TypedValueRegion *baseR = dyn_cast<TypedValueRegion>(O.getRegion()))
if (auto V = getDerivedSymbolForBinding(B, baseR, R, Ctx, svalBuilder))
return *V;
return getBindingForFieldOrElementCommon(B, R, R->getElementType());
}
SVal RegionStoreManager::getBindingForField(RegionBindingsConstRef B,
const FieldRegion* R) {
// Check if the region has a binding.
if (const std::optional<SVal> &V = B.getDirectBinding(R))
return *V;
// If the containing record was initialized, try to get its constant value.
const FieldDecl *FD = R->getDecl();
QualType Ty = FD->getType();
const MemRegion* superR = R->getSuperRegion();
if (const auto *VR = dyn_cast<VarRegion>(superR)) {
const VarDecl *VD = VR->getDecl();
QualType RecordVarTy = VD->getType();
unsigned Index = FD->getFieldIndex();
// Either the record variable or the field has an initializer that we can
// trust. We trust initializers of constants and, additionally, respect
// initializers of globals when analyzing main().
if (RecordVarTy.isConstQualified() || Ty.isConstQualified() ||
(B.isMainAnalysis() && VD->hasGlobalStorage()))
if (const Expr *Init = VD->getAnyInitializer())
if (const auto *InitList = dyn_cast<InitListExpr>(Init)) {
if (Index < InitList->getNumInits()) {
if (const Expr *FieldInit = InitList->getInit(Index))
if (std::optional<SVal> V = svalBuilder.getConstantVal(FieldInit))
return *V;
} else {
return svalBuilder.makeZeroVal(Ty);
}
}
}
// Handle the case where we are accessing into a larger scalar object.
// For example, this handles:
// struct header {
// unsigned a : 1;
// unsigned b : 1;
// };
// struct parse_t {
// unsigned bits0 : 1;
// unsigned bits2 : 2; // <-- header
// unsigned bits4 : 4;
// };
// int parse(parse_t *p) {
// unsigned copy = p->bits2;
// header *bits = (header *)&copy;
// return bits->b; <-- here
// }
if (const auto *Base = dyn_cast<TypedValueRegion>(R->getBaseRegion()))
if (auto V = getDerivedSymbolForBinding(B, Base, R, Ctx, svalBuilder))
return *V;
return getBindingForFieldOrElementCommon(B, R, Ty);
}
std::optional<SVal> RegionStoreManager::getBindingForDerivedDefaultValue(
RegionBindingsConstRef B, const MemRegion *superR,
const TypedValueRegion *R, QualType Ty) {
if (const std::optional<SVal> &D = B.getDefaultBinding(superR)) {
SVal val = *D;
if (SymbolRef parentSym = val.getAsSymbol())
return svalBuilder.getDerivedRegionValueSymbolVal(parentSym, R);
if (val.isZeroConstant())
return svalBuilder.makeZeroVal(Ty);
if (val.isUnknownOrUndef())
return val;
// Lazy bindings are usually handled through getExistingLazyBinding().
// We should unify these two code paths at some point.
if (isa<nonloc::LazyCompoundVal, nonloc::CompoundVal>(val))
return val;
llvm_unreachable("Unknown default value");
}
return std::nullopt;
}
SVal RegionStoreManager::getLazyBinding(const SubRegion *LazyBindingRegion,
RegionBindingsRef LazyBinding) {
SVal Result;
if (const ElementRegion *ER = dyn_cast<ElementRegion>(LazyBindingRegion))
Result = getBindingForElement(LazyBinding, ER);
else
Result = getBindingForField(LazyBinding,
cast<FieldRegion>(LazyBindingRegion));
// FIXME: This is a hack to deal with RegionStore's inability to distinguish a
// default value for /part/ of an aggregate from a default value for the
// /entire/ aggregate. The most common case of this is when struct Outer
// has as its first member a struct Inner, which is copied in from a stack
// variable. In this case, even if the Outer's default value is symbolic, 0,
// or unknown, it gets overridden by the Inner's default value of undefined.
//
// This is a general problem -- if the Inner is zero-initialized, the Outer
// will now look zero-initialized. The proper way to solve this is with a
// new version of RegionStore that tracks the extent of a binding as well
// as the offset.
//
// This hack only takes care of the undefined case because that can very
// quickly result in a warning.
if (Result.isUndef())
Result = UnknownVal();
return Result;
}
SVal
RegionStoreManager::getBindingForFieldOrElementCommon(RegionBindingsConstRef B,
const TypedValueRegion *R,
QualType Ty) {
// At this point we have already checked in either getBindingForElement or
// getBindingForField if 'R' has a direct binding.
// Lazy binding?
Store lazyBindingStore = nullptr;
const SubRegion *lazyBindingRegion = nullptr;
std::tie(lazyBindingStore, lazyBindingRegion) = findLazyBinding(B, R, R);
if (lazyBindingRegion)
return getLazyBinding(lazyBindingRegion,
getRegionBindings(lazyBindingStore));
// Record whether or not we see a symbolic index. That can completely
// be out of scope of our lookup.
bool hasSymbolicIndex = false;
// FIXME: This is a hack to deal with RegionStore's inability to distinguish a
// default value for /part/ of an aggregate from a default value for the
// /entire/ aggregate. The most common case of this is when struct Outer
// has as its first member a struct Inner, which is copied in from a stack
// variable. In this case, even if the Outer's default value is symbolic, 0,
// or unknown, it gets overridden by the Inner's default value of undefined.
//
// This is a general problem -- if the Inner is zero-initialized, the Outer
// will now look zero-initialized. The proper way to solve this is with a
// new version of RegionStore that tracks the extent of a binding as well
// as the offset.
//
// This hack only takes care of the undefined case because that can very
// quickly result in a warning.
bool hasPartialLazyBinding = false;
const SubRegion *SR = R;
while (SR) {
const MemRegion *Base = SR->getSuperRegion();
if (std::optional<SVal> D =
getBindingForDerivedDefaultValue(B, Base, R, Ty)) {
if (D->getAs<nonloc::LazyCompoundVal>()) {
hasPartialLazyBinding = true;
break;
}
return *D;
}
if (const ElementRegion *ER = dyn_cast<ElementRegion>(Base)) {
NonLoc index = ER->getIndex();
if (!index.isConstant())
hasSymbolicIndex = true;
}
// If our super region is a field or element itself, walk up the region
// hierarchy to see if there is a default value installed in an ancestor.
SR = dyn_cast<SubRegion>(Base);
}
if (isa<StackLocalsSpaceRegion>(R->getRawMemorySpace())) {
if (isa<ElementRegion>(R)) {
// Currently we don't reason specially about Clang-style vectors. Check
// if superR is a vector and if so return Unknown.
if (const TypedValueRegion *typedSuperR =
dyn_cast<TypedValueRegion>(R->getSuperRegion())) {
if (typedSuperR->getValueType()->isVectorType())
return UnknownVal();
}
}
// FIXME: We also need to take ElementRegions with symbolic indexes into
// account. This case handles both directly accessing an ElementRegion
// with a symbolic offset, but also fields within an element with
// a symbolic offset.
if (hasSymbolicIndex)
return UnknownVal();
// Additionally allow introspection of a block's internal layout.
// Try to get direct binding if all other attempts failed thus far.
// Else, return UndefinedVal()
if (!hasPartialLazyBinding && !isa<BlockDataRegion>(R->getBaseRegion())) {
if (const std::optional<SVal> &V = B.getDefaultBinding(R))
return *V;
return UndefinedVal();
}
}
// All other values are symbolic.
return svalBuilder.getRegionValueSymbolVal(R);
}
SVal RegionStoreManager::getBindingForObjCIvar(RegionBindingsConstRef B,
const ObjCIvarRegion* R) {
// Check if the region has a binding.
if (const std::optional<SVal> &V = B.getDirectBinding(R))
return *V;
const MemRegion *superR = R->getSuperRegion();
// Check if the super region has a default binding.
if (const std::optional<SVal> &V = B.getDefaultBinding(superR)) {
if (SymbolRef parentSym = V->getAsSymbol())
return svalBuilder.getDerivedRegionValueSymbolVal(parentSym, R);
// Other cases: give up.
return UnknownVal();
}
return getBindingForLazySymbol(R);
}
SVal RegionStoreManager::getBindingForVar(RegionBindingsConstRef B,
const VarRegion *R) {
// Check if the region has a binding.
if (std::optional<SVal> V = B.getDirectBinding(R))
return *V;
if (std::optional<SVal> V = B.getDefaultBinding(R))
return *V;
// Lazily derive a value for the VarRegion.
const VarDecl *VD = R->getDecl();
const MemSpaceRegion *MS = R->getRawMemorySpace();
// Arguments are always symbolic.
if (isa<StackArgumentsSpaceRegion>(MS))
return svalBuilder.getRegionValueSymbolVal(R);
// Is 'VD' declared constant? If so, retrieve the constant value.
if (VD->getType().isConstQualified()) {
if (const Expr *Init = VD->getAnyInitializer()) {
if (std::optional<SVal> V = svalBuilder.getConstantVal(Init))
return *V;
// If the variable is const qualified and has an initializer but
// we couldn't evaluate initializer to a value, treat the value as
// unknown.
return UnknownVal();
}
}
// This must come after the check for constants because closure-captured
// constant variables may appear in UnknownSpaceRegion.
if (isa<UnknownSpaceRegion>(MS))
return svalBuilder.getRegionValueSymbolVal(R);
if (isa<GlobalsSpaceRegion>(MS)) {
QualType T = VD->getType();
// If we're in main(), then global initializers have not become stale yet.
if (B.isMainAnalysis())
if (const Expr *Init = VD->getAnyInitializer())
if (std::optional<SVal> V = svalBuilder.getConstantVal(Init))
return *V;
// Function-scoped static variables are default-initialized to 0; if they
// have an initializer, it would have been processed by now.
// FIXME: This is only true when we're starting analysis from main().
// We're losing a lot of coverage here.
if (isa<StaticGlobalSpaceRegion>(MS))
return svalBuilder.makeZeroVal(T);
if (std::optional<SVal> V = getBindingForDerivedDefaultValue(B, MS, R, T)) {
assert(!V->getAs<nonloc::LazyCompoundVal>());
return *V;
}
return svalBuilder.getRegionValueSymbolVal(R);
}
return UndefinedVal();
}
SVal RegionStoreManager::getBindingForLazySymbol(const TypedValueRegion *R) {
// All other values are symbolic.
return svalBuilder.getRegionValueSymbolVal(R);
}
const RegionStoreManager::SValListTy &
RegionStoreManager::getInterestingValues(nonloc::LazyCompoundVal LCV) {
// First, check the cache.
LazyBindingsMapTy::iterator I = LazyBindingsMap.find(LCV.getCVData());
if (I != LazyBindingsMap.end())
return I->second;
// If we don't have a list of values cached, start constructing it.
SValListTy List;
const SubRegion *LazyR = LCV.getRegion();
RegionBindingsRef B = getRegionBindings(LCV.getStore());
// If this region had /no/ bindings at the time, there are no interesting
// values to return.
const ClusterBindings *Cluster = B.lookup(LazyR->getBaseRegion());
if (!Cluster)
return (LazyBindingsMap[LCV.getCVData()] = std::move(List));
SmallVector<BindingPair, 32> Bindings;
collectSubRegionBindings(Bindings, svalBuilder, *Cluster, LazyR,
/*IncludeAllDefaultBindings=*/true);
for (SVal V : llvm::make_second_range(Bindings)) {
if (V.isUnknownOrUndef() || V.isConstant())
continue;
if (auto InnerLCV = V.getAs<nonloc::LazyCompoundVal>()) {
const SValListTy &InnerList = getInterestingValues(*InnerLCV);
List.insert(List.end(), InnerList.begin(), InnerList.end());
}
List.push_back(V);
}
return (LazyBindingsMap[LCV.getCVData()] = std::move(List));
}
NonLoc RegionStoreManager::createLazyBinding(RegionBindingsConstRef B,
const TypedValueRegion *R) {
if (std::optional<nonloc::LazyCompoundVal> V =
getExistingLazyBinding(svalBuilder, B, R, false))
return *V;
return svalBuilder.makeLazyCompoundVal(StoreRef(B.asStore(), *this), R);
}
SVal RegionStoreManager::getBindingForStruct(RegionBindingsConstRef B,
const TypedValueRegion *R) {
const RecordDecl *RD = R->getValueType()->castAs<RecordType>()->getDecl();
if (!RD->getDefinition())
return UnknownVal();
// We also create a LCV for copying empty structs because then the store
// behavior doesn't depend on the struct layout.
// This way even an empty struct can carry taint, no matter if creduce drops
// the last field member or not.
// Try to avoid creating a LCV if it would anyways just refer to a single
// default binding.
if (std::optional<SVal> Val = getUniqueDefaultBinding(B, R))
return *Val;
return createLazyBinding(B, R);
}
SVal RegionStoreManager::getBindingForArray(RegionBindingsConstRef B,
const TypedValueRegion *R) {
assert(Ctx.getAsConstantArrayType(R->getValueType()) &&
"Only constant array types can have compound bindings.");
return createLazyBinding(B, R);
}
bool RegionStoreManager::includedInBindings(Store store,
const MemRegion *region) const {
RegionBindingsRef B = getRegionBindings(store);
region = region->getBaseRegion();
// Quick path: if the base is the head of a cluster, the region is live.
if (B.lookup(region))
return true;
// Slow path: if the region is the VALUE of any binding, it is live.
for (RegionBindingsRef::iterator RI = B.begin(), RE = B.end(); RI != RE; ++RI) {
const ClusterBindings &Cluster = RI.getData();
for (ClusterBindings::iterator CI = Cluster.begin(), CE = Cluster.end();
CI != CE; ++CI) {
SVal D = CI.getData();
if (const MemRegion *R = D.getAsRegion())
if (R->getBaseRegion() == region)
return true;
}
}
return false;
}
//===----------------------------------------------------------------------===//
// Binding values to regions.
//===----------------------------------------------------------------------===//
StoreRef RegionStoreManager::killBinding(Store ST, Loc L) {
if (std::optional<loc::MemRegionVal> LV = L.getAs<loc::MemRegionVal>())
if (const MemRegion* R = LV->getRegion())
return StoreRef(getRegionBindings(ST).removeBinding(R)
.asImmutableMap()
.getRootWithoutRetain(),
*this);
return StoreRef(ST, *this);
}
RegionBindingsRef
RegionStoreManager::bind(RegionBindingsConstRef B, Loc L, SVal V) {
llvm::TimeTraceScope TimeScope("RegionStoreManager::bind",
[&L]() { return locDescr(L); });
// We only care about region locations.
auto MemRegVal = L.getAs<loc::MemRegionVal>();
if (!MemRegVal)
return B;
const MemRegion *R = MemRegVal->getRegion();
// Check if the region is a struct region.
if (const TypedValueRegion* TR = dyn_cast<TypedValueRegion>(R)) {
QualType Ty = TR->getValueType();
if (Ty->isArrayType())
return bindArray(B, TR, V);
if (Ty->isStructureOrClassType())
return bindStruct(B, TR, V);
if (Ty->isVectorType())
return bindVector(B, TR, V);
if (Ty->isUnionType())
return bindAggregate(B, TR, V);
}
// Binding directly to a symbolic region should be treated as binding
// to element 0.
if (const auto *SymReg = dyn_cast<SymbolicRegion>(R)) {
QualType Ty = SymReg->getPointeeStaticType();
if (Ty->isVoidType())
Ty = StateMgr.getContext().CharTy;
R = GetElementZeroRegion(SymReg, Ty);
}
assert((!isa<CXXThisRegion>(R) || !B.lookup(R)) &&
"'this' pointer is not an l-value and is not assignable");
// Clear out bindings that may overlap with this binding.
RegionBindingsRef NewB = removeSubRegionBindings(B, cast<SubRegion>(R));
// LazyCompoundVals should be always bound as 'default' bindings.
auto KeyKind = isa<nonloc::LazyCompoundVal>(V) ? BindingKey::Default
: BindingKey::Direct;
return NewB.addBinding(BindingKey::Make(R, KeyKind), V);
}
RegionBindingsRef
RegionStoreManager::setImplicitDefaultValue(RegionBindingsConstRef B,
const MemRegion *R,
QualType T) {
SVal V;
if (Loc::isLocType(T))
V = svalBuilder.makeNullWithType(T);
else if (T->isIntegralOrEnumerationType())
V = svalBuilder.makeZeroVal(T);
else if (T->isStructureOrClassType() || T->isArrayType()) {
// Set the default value to a zero constant when it is a structure
// or array. The type doesn't really matter.
V = svalBuilder.makeZeroVal(Ctx.IntTy);
}
else {
// We can't represent values of this type, but we still need to set a value
// to record that the region has been initialized.
// If this assertion ever fires, a new case should be added above -- we
// should know how to default-initialize any value we can symbolicate.
assert(!SymbolManager::canSymbolicate(T) && "This type is representable");
V = UnknownVal();
}
return B.addBinding(R, BindingKey::Default, V);
}
std::optional<RegionBindingsRef> RegionStoreManager::tryBindSmallArray(
RegionBindingsConstRef B, const TypedValueRegion *R, const ArrayType *AT,
nonloc::LazyCompoundVal LCV) {
auto CAT = dyn_cast<ConstantArrayType>(AT);
// If we don't know the size, create a lazyCompoundVal instead.
if (!CAT)
return std::nullopt;
QualType Ty = CAT->getElementType();
if (!(Ty->isScalarType() || Ty->isReferenceType()))
return std::nullopt;
// If the array is too big, create a LCV instead.
uint64_t ArrSize = CAT->getLimitedSize();
if (ArrSize > SmallArrayLimit)
return std::nullopt;
RegionBindingsRef NewB = B;
for (uint64_t i = 0; i < ArrSize; ++i) {
auto Idx = svalBuilder.makeArrayIndex(i);
const ElementRegion *SrcER =
MRMgr.getElementRegion(Ty, Idx, LCV.getRegion(), Ctx);
SVal V = getBindingForElement(getRegionBindings(LCV.getStore()), SrcER);
const ElementRegion *DstER = MRMgr.getElementRegion(Ty, Idx, R, Ctx);
NewB = bind(NewB, loc::MemRegionVal(DstER), V);
}
return NewB;
}
RegionBindingsRef
RegionStoreManager::bindArray(RegionBindingsConstRef B,
const TypedValueRegion* R,
SVal Init) {
llvm::TimeTraceScope TimeScope("RegionStoreManager::bindArray",
[R]() { return R->getDescriptiveName(); });
const ArrayType *AT =cast<ArrayType>(Ctx.getCanonicalType(R->getValueType()));
QualType ElementTy = AT->getElementType();
std::optional<uint64_t> Size;
if (const ConstantArrayType* CAT = dyn_cast<ConstantArrayType>(AT))
Size = CAT->getZExtSize();
// Check if the init expr is a literal. If so, bind the rvalue instead.
// FIXME: It's not responsibility of the Store to transform this lvalue
// to rvalue. ExprEngine or maybe even CFG should do this before binding.
if (std::optional<loc::MemRegionVal> MRV = Init.getAs<loc::MemRegionVal>()) {
SVal V = getBinding(B.asStore(), *MRV, R->getValueType());
return bindAggregate(B, R, V);
}
// Handle lazy compound values.
if (std::optional<nonloc::LazyCompoundVal> LCV =
Init.getAs<nonloc::LazyCompoundVal>()) {
if (std::optional<RegionBindingsRef> NewB =
tryBindSmallArray(B, R, AT, *LCV))
return *NewB;
return bindAggregate(B, R, Init);
}
if (Init.isUnknown())
return bindAggregate(B, R, UnknownVal());
// Remaining case: explicit compound values.
const nonloc::CompoundVal& CV = Init.castAs<nonloc::CompoundVal>();
nonloc::CompoundVal::iterator VI = CV.begin(), VE = CV.end();
uint64_t i = 0;
RegionBindingsRef NewB(B);
for (; Size ? i < *Size : true; ++i, ++VI) {
// The init list might be shorter than the array length.
if (VI == VE)
break;
NonLoc Idx = svalBuilder.makeArrayIndex(i);
const ElementRegion *ER = MRMgr.getElementRegion(ElementTy, Idx, R, Ctx);
if (ElementTy->isStructureOrClassType())
NewB = bindStruct(NewB, ER, *VI);
else if (ElementTy->isArrayType())
NewB = bindArray(NewB, ER, *VI);
else
NewB = bind(NewB, loc::MemRegionVal(ER), *VI);
}
// If the init list is shorter than the array length (or the array has
// variable length), set the array default value. Values that are already set
// are not overwritten.
if (!Size || i < *Size)
NewB = setImplicitDefaultValue(NewB, R, ElementTy);
return NewB;
}
RegionBindingsRef RegionStoreManager::bindVector(RegionBindingsConstRef B,
const TypedValueRegion* R,
SVal V) {
llvm::TimeTraceScope TimeScope("RegionStoreManager::bindVector",
[R]() { return R->getDescriptiveName(); });
QualType T = R->getValueType();
const VectorType *VT = T->castAs<VectorType>(); // Use castAs for typedefs.
// Handle lazy compound values and symbolic values.
if (isa<nonloc::LazyCompoundVal, nonloc::SymbolVal>(V))
return bindAggregate(B, R, V);
// We may get non-CompoundVal accidentally due to imprecise cast logic or
// that we are binding symbolic struct value. Kill the field values, and if
// the value is symbolic go and bind it as a "default" binding.
if (!isa<nonloc::CompoundVal>(V)) {
return bindAggregate(B, R, UnknownVal());
}
QualType ElemType = VT->getElementType();
nonloc::CompoundVal CV = V.castAs<nonloc::CompoundVal>();
nonloc::CompoundVal::iterator VI = CV.begin(), VE = CV.end();
unsigned index = 0, numElements = VT->getNumElements();
RegionBindingsRef NewB(B);
for ( ; index != numElements ; ++index) {
if (VI == VE)
break;
NonLoc Idx = svalBuilder.makeArrayIndex(index);
const ElementRegion *ER = MRMgr.getElementRegion(ElemType, Idx, R, Ctx);
if (ElemType->isArrayType())
NewB = bindArray(NewB, ER, *VI);
else if (ElemType->isStructureOrClassType())
NewB = bindStruct(NewB, ER, *VI);
else
NewB = bind(NewB, loc::MemRegionVal(ER), *VI);
}
return NewB;
}
std::optional<SVal>
RegionStoreManager::getUniqueDefaultBinding(RegionBindingsConstRef B,
const TypedValueRegion *R) const {
if (R != R->getBaseRegion())
return std::nullopt;
const auto *Cluster = B.lookup(R);
if (!Cluster || !llvm::hasSingleElement(*Cluster))
return std::nullopt;
const auto [Key, Value] = *Cluster->begin();
return Key.isDirect() ? std::optional<SVal>{} : Value;
}
std::optional<SVal>
RegionStoreManager::getUniqueDefaultBinding(nonloc::LazyCompoundVal LCV) const {
RegionBindingsConstRef B = getRegionBindings(LCV.getStore());
return getUniqueDefaultBinding(B, LCV.getRegion());
}
std::optional<RegionBindingsRef> RegionStoreManager::tryBindSmallStruct(
RegionBindingsConstRef B, const TypedValueRegion *R, const RecordDecl *RD,
nonloc::LazyCompoundVal LCV) {
// If we try to copy a Conjured value representing the value of the whole
// struct, don't try to element-wise copy each field.
// That would unnecessarily bind Derived symbols slicing off the subregion for
// the field from the whole Conjured symbol.
//
// struct Window { int width; int height; };
// Window getWindow(); <-- opaque fn.
// Window w = getWindow(); <-- conjures a new Window.
// Window w2 = w; <-- trivial copy "w", calling "tryBindSmallStruct"
//
// We should not end up with a new Store for "w2" like this:
// Direct [ 0..31]: Derived{Conj{}, w.width}
// Direct [32..63]: Derived{Conj{}, w.height}
// Instead, we should just bind that Conjured value instead.
if (std::optional<SVal> Val = getUniqueDefaultBinding(LCV)) {
return B.addBinding(BindingKey::Make(R, BindingKey::Default), Val.value());
}
FieldVector Fields;
if (const CXXRecordDecl *Class = dyn_cast<CXXRecordDecl>(RD))
if (Class->getNumBases() != 0 || Class->getNumVBases() != 0)
return std::nullopt;
for (const auto *FD : RD->fields()) {
if (FD->isUnnamedBitField())
continue;
// If there are too many fields, or if any of the fields are aggregates,
// just use the LCV as a default binding.
if (Fields.size() == SmallStructLimit)
return std::nullopt;
QualType Ty = FD->getType();
// Zero length arrays are basically no-ops, so we also ignore them here.
if (Ty->isConstantArrayType() &&
Ctx.getConstantArrayElementCount(Ctx.getAsConstantArrayType(Ty)) == 0)
continue;
if (!(Ty->isScalarType() || Ty->isReferenceType()))
return std::nullopt;
Fields.push_back(FD);
}
RegionBindingsRef NewB = B;
for (const FieldDecl *Field : Fields) {
const FieldRegion *SourceFR = MRMgr.getFieldRegion(Field, LCV.getRegion());
SVal V = getBindingForField(getRegionBindings(LCV.getStore()), SourceFR);
const FieldRegion *DestFR = MRMgr.getFieldRegion(Field, R);
NewB = bind(NewB, loc::MemRegionVal(DestFR), V);
}
return NewB;
}
RegionBindingsRef RegionStoreManager::bindStruct(RegionBindingsConstRef B,
const TypedValueRegion *R,
SVal V) {
llvm::TimeTraceScope TimeScope("RegionStoreManager::bindStruct",
[R]() { return R->getDescriptiveName(); });
QualType T = R->getValueType();
assert(T->isStructureOrClassType());
const RecordType* RT = T->castAs<RecordType>();
const RecordDecl *RD = RT->getDecl();
if (!RD->isCompleteDefinition())
return B;
// Handle lazy compound values and symbolic values.
if (std::optional<nonloc::LazyCompoundVal> LCV =
V.getAs<nonloc::LazyCompoundVal>()) {
if (std::optional<RegionBindingsRef> NewB =
tryBindSmallStruct(B, R, RD, *LCV))
return *NewB;
return bindAggregate(B, R, V);
}
if (isa<nonloc::SymbolVal>(V))
return bindAggregate(B, R, V);
// We may get non-CompoundVal accidentally due to imprecise cast logic or
// that we are binding symbolic struct value. Kill the field values, and if
// the value is symbolic go and bind it as a "default" binding.
if (V.isUnknown() || !isa<nonloc::CompoundVal>(V))
return bindAggregate(B, R, UnknownVal());
// The raw CompoundVal is essentially a symbolic InitListExpr: an (immutable)
// list of other values. It appears pretty much only when there's an actual
// initializer list expression in the program, and the analyzer tries to
// unwrap it as soon as possible.
// This code is where such unwrap happens: when the compound value is put into
// the object that it was supposed to initialize (it's an *initializer* list,
// after all), instead of binding the whole value to the whole object, we bind
// sub-values to sub-objects. Sub-values may themselves be compound values,
// and in this case the procedure becomes recursive.
// FIXME: The annoying part about compound values is that they don't carry
// any sort of information about which value corresponds to which sub-object.
// It's simply a list of values in the middle of nowhere; we expect to match
// them to sub-objects, essentially, "by index": first value binds to
// the first field, second value binds to the second field, etc.
// It would have been much safer to organize non-lazy compound values as
// a mapping from fields/bases to values.
const nonloc::CompoundVal& CV = V.castAs<nonloc::CompoundVal>();
nonloc::CompoundVal::iterator VI = CV.begin(), VE = CV.end();
RegionBindingsRef NewB(B);
// In C++17 aggregates may have base classes, handle those as well.
// They appear before fields in the initializer list / compound value.
if (const auto *CRD = dyn_cast<CXXRecordDecl>(RD)) {
// If the object was constructed with a constructor, its value is a
// LazyCompoundVal. If it's a raw CompoundVal, it means that we're
// performing aggregate initialization. The only exception from this
// rule is sending an Objective-C++ message that returns a C++ object
// to a nil receiver; in this case the semantics is to return a
// zero-initialized object even if it's a C++ object that doesn't have
// this sort of constructor; the CompoundVal is empty in this case.
assert((CRD->isAggregate() || (Ctx.getLangOpts().ObjC && VI == VE)) &&
"Non-aggregates are constructed with a constructor!");
for (const auto &B : CRD->bases()) {
// (Multiple inheritance is fine though.)
assert(!B.isVirtual() && "Aggregates cannot have virtual base classes!");
if (VI == VE)
break;
QualType BTy = B.getType();
assert(BTy->isStructureOrClassType() && "Base classes must be classes!");
const CXXRecordDecl *BRD = BTy->getAsCXXRecordDecl();
assert(BRD && "Base classes must be C++ classes!");
const CXXBaseObjectRegion *BR =
MRMgr.getCXXBaseObjectRegion(BRD, R, /*IsVirtual=*/false);
NewB = bindStruct(NewB, BR, *VI);
++VI;
}
}
RecordDecl::field_iterator FI, FE;
for (FI = RD->field_begin(), FE = RD->field_end(); FI != FE; ++FI) {
if (VI == VE)
break;
// Skip any unnamed bitfields to stay in sync with the initializers.
if (FI->isUnnamedBitField())
continue;
QualType FTy = FI->getType();
const FieldRegion* FR = MRMgr.getFieldRegion(*FI, R);
if (FTy->isArrayType())
NewB = bindArray(NewB, FR, *VI);
else if (FTy->isStructureOrClassType())
NewB = bindStruct(NewB, FR, *VI);
else
NewB = bind(NewB, loc::MemRegionVal(FR), *VI);
++VI;
}
// There may be fewer values in the initialize list than the fields of struct.
if (FI != FE) {
NewB = NewB.addBinding(R, BindingKey::Default,
svalBuilder.makeIntVal(0, false));
}
return NewB;
}
RegionBindingsRef
RegionStoreManager::bindAggregate(RegionBindingsConstRef B,
const TypedRegion *R,
SVal Val) {
llvm::TimeTraceScope TimeScope("RegionStoreManager::bindAggregate",
[R]() { return R->getDescriptiveName(); });
// Remove the old bindings, using 'R' as the root of all regions
// we will invalidate. Then add the new binding.
return removeSubRegionBindings(B, R).addBinding(R, BindingKey::Default, Val);
}
//===----------------------------------------------------------------------===//
// State pruning.
//===----------------------------------------------------------------------===//
namespace {
class RemoveDeadBindingsWorker
: public ClusterAnalysis<RemoveDeadBindingsWorker> {
SmallVector<const SymbolicRegion *, 12> Postponed;
SymbolReaper &SymReaper;
const StackFrameContext *CurrentLCtx;
public:
RemoveDeadBindingsWorker(RegionStoreManager &rm,
ProgramStateManager &stateMgr,
RegionBindingsRef b, SymbolReaper &symReaper,
const StackFrameContext *LCtx)
: ClusterAnalysis<RemoveDeadBindingsWorker>(rm, stateMgr, b),
SymReaper(symReaper), CurrentLCtx(LCtx) {}
// Called by ClusterAnalysis.
void VisitAddedToCluster(const MemRegion *baseR, const ClusterBindings &C);
void VisitCluster(const MemRegion *baseR, const ClusterBindings *C);
using ClusterAnalysis<RemoveDeadBindingsWorker>::VisitCluster;
using ClusterAnalysis::AddToWorkList;
bool AddToWorkList(const MemRegion *R);
bool UpdatePostponed();
void VisitBinding(SVal V);
};
}
bool RemoveDeadBindingsWorker::AddToWorkList(const MemRegion *R) {
const MemRegion *BaseR = R->getBaseRegion();
return AddToWorkList(WorkListElement(BaseR), getCluster(BaseR));
}
void RemoveDeadBindingsWorker::VisitAddedToCluster(const MemRegion *baseR,
const ClusterBindings &C) {
if (const VarRegion *VR = dyn_cast<VarRegion>(baseR)) {
if (SymReaper.isLive(VR))
AddToWorkList(baseR, &C);
return;
}
if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(baseR)) {
if (SymReaper.isLive(SR->getSymbol()))
AddToWorkList(SR, &C);
else
Postponed.push_back(SR);
return;
}
if (isa<NonStaticGlobalSpaceRegion>(baseR)) {
AddToWorkList(baseR, &C);
return;
}
// CXXThisRegion in the current or parent location context is live.
if (const CXXThisRegion *TR = dyn_cast<CXXThisRegion>(baseR)) {
const auto *StackReg =
cast<StackArgumentsSpaceRegion>(TR->getSuperRegion());
const StackFrameContext *RegCtx = StackReg->getStackFrame();
if (CurrentLCtx &&
(RegCtx == CurrentLCtx || RegCtx->isParentOf(CurrentLCtx)))
AddToWorkList(TR, &C);
}
}
void RemoveDeadBindingsWorker::VisitCluster(const MemRegion *baseR,
const ClusterBindings *C) {
if (!C)
return;
// Mark the symbol for any SymbolicRegion with live bindings as live itself.
// This means we should continue to track that symbol.
if (const SymbolicRegion *SymR = dyn_cast<SymbolicRegion>(baseR))
SymReaper.markLive(SymR->getSymbol());
for (const auto &[Key, Val] : *C) {
// Element index of a binding key is live.
SymReaper.markElementIndicesLive(Key.getRegion());
VisitBinding(Val);
}
}
void RemoveDeadBindingsWorker::VisitBinding(SVal V) {
// Is it a LazyCompoundVal? All referenced regions are live as well.
// The LazyCompoundVal itself is not live but should be readable.
if (auto LCS = V.getAs<nonloc::LazyCompoundVal>()) {
SymReaper.markLazilyCopied(LCS->getRegion());
for (SVal V : RM.getInterestingValues(*LCS)) {
if (auto DepLCS = V.getAs<nonloc::LazyCompoundVal>())
SymReaper.markLazilyCopied(DepLCS->getRegion());
else
VisitBinding(V);
}
return;
}
// If V is a region, then add it to the worklist.
if (const MemRegion *R = V.getAsRegion()) {
AddToWorkList(R);
SymReaper.markLive(R);
// All regions captured by a block are also live.
if (const BlockDataRegion *BR = dyn_cast<BlockDataRegion>(R)) {
for (auto Var : BR->referenced_vars())
AddToWorkList(Var.getCapturedRegion());
}
}
// Update the set of live symbols.
for (SymbolRef Sym : V.symbols())
SymReaper.markLive(Sym);
}
bool RemoveDeadBindingsWorker::UpdatePostponed() {
// See if any postponed SymbolicRegions are actually live now, after
// having done a scan.
bool Changed = false;
for (const SymbolicRegion *SR : Postponed) {
if (SymReaper.isLive(SR->getSymbol())) {
Changed |= AddToWorkList(SR);
SR = nullptr;
}
}
return Changed;
}
StoreRef RegionStoreManager::removeDeadBindings(Store store,
const StackFrameContext *LCtx,
SymbolReaper& SymReaper) {
RegionBindingsRef B = getRegionBindings(store);
RemoveDeadBindingsWorker W(*this, StateMgr, B, SymReaper, LCtx);
W.GenerateClusters();
// Enqueue the region roots onto the worklist.
for (const MemRegion *Reg : SymReaper.regions()) {
W.AddToWorkList(Reg);
}
do W.RunWorkList(); while (W.UpdatePostponed());
// We have now scanned the store, marking reachable regions and symbols
// as live. We now remove all the regions that are dead from the store
// as well as update DSymbols with the set symbols that are now dead.
for (const MemRegion *Base : llvm::make_first_range(B)) {
// If the cluster has been visited, we know the region has been marked.
// Otherwise, remove the dead entry.
if (!W.isVisited(Base))
B = B.remove(Base);
}
return StoreRef(B.asStore(), *this);
}
//===----------------------------------------------------------------------===//
// Utility methods.
//===----------------------------------------------------------------------===//
void RegionStoreManager::printJson(raw_ostream &Out, Store S, const char *NL,
unsigned int Space, bool IsDot) const {
RegionBindingsRef Bindings = getRegionBindings(S);
Indent(Out, Space, IsDot) << "\"store\": ";
if (Bindings.isEmpty()) {
Out << "null," << NL;
return;
}
Out << "{ \"pointer\": \"" << Bindings.asStore() << "\", \"items\": [" << NL;
Bindings.printJson(Out, NL, Space + 1, IsDot);
Indent(Out, Space, IsDot) << "]}," << NL;
}