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ExprEngine.cpp
3288 lines (2845 loc) · 121 KB
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ExprEngine.cpp
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//===- ExprEngine.cpp - Path-Sensitive Expression-Level Dataflow ----------===//
//
// 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 meta-engine for path-sensitive dataflow analysis that
// is built on GREngine, but provides the boilerplate to execute transfer
// functions and build the ExplodedGraph at the expression level.
//
//===----------------------------------------------------------------------===//
#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
#include "PrettyStackTraceLocationContext.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclBase.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/ExprObjC.h"
#include "clang/AST/ParentMap.h"
#include "clang/AST/PrettyPrinter.h"
#include "clang/AST/Stmt.h"
#include "clang/AST/StmtCXX.h"
#include "clang/AST/StmtObjC.h"
#include "clang/AST/Type.h"
#include "clang/Analysis/AnalysisDeclContext.h"
#include "clang/Analysis/CFG.h"
#include "clang/Analysis/ConstructionContext.h"
#include "clang/Analysis/ProgramPoint.h"
#include "clang/Basic/IdentifierTable.h"
#include "clang/Basic/JsonSupport.h"
#include "clang/Basic/LLVM.h"
#include "clang/Basic/LangOptions.h"
#include "clang/Basic/PrettyStackTrace.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/Specifiers.h"
#include "clang/StaticAnalyzer/Core/AnalyzerOptions.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ConstraintManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CoreEngine.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/LoopUnrolling.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/LoopWidening.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState_Fwd.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/Store.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SymExpr.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
#include "llvm/ADT/APSInt.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/ImmutableMap.h"
#include "llvm/ADT/ImmutableSet.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/DOTGraphTraits.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/GraphWriter.h"
#include "llvm/Support/SaveAndRestore.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
#include <cstdint>
#include <memory>
#include <string>
#include <tuple>
#include <utility>
#include <vector>
using namespace clang;
using namespace ento;
#define DEBUG_TYPE "ExprEngine"
STATISTIC(NumRemoveDeadBindings,
"The # of times RemoveDeadBindings is called");
STATISTIC(NumMaxBlockCountReached,
"The # of aborted paths due to reaching the maximum block count in "
"a top level function");
STATISTIC(NumMaxBlockCountReachedInInlined,
"The # of aborted paths due to reaching the maximum block count in "
"an inlined function");
STATISTIC(NumTimesRetriedWithoutInlining,
"The # of times we re-evaluated a call without inlining");
//===----------------------------------------------------------------------===//
// Internal program state traits.
//===----------------------------------------------------------------------===//
namespace {
// When modeling a C++ constructor, for a variety of reasons we need to track
// the location of the object for the duration of its ConstructionContext.
// ObjectsUnderConstruction maps statements within the construction context
// to the object's location, so that on every such statement the location
// could have been retrieved.
/// ConstructedObjectKey is used for being able to find the path-sensitive
/// memory region of a freshly constructed object while modeling the AST node
/// that syntactically represents the object that is being constructed.
/// Semantics of such nodes may sometimes require access to the region that's
/// not otherwise present in the program state, or to the very fact that
/// the construction context was present and contained references to these
/// AST nodes.
class ConstructedObjectKey {
typedef std::pair<ConstructionContextItem, const LocationContext *>
ConstructedObjectKeyImpl;
const ConstructedObjectKeyImpl Impl;
const void *getAnyASTNodePtr() const {
if (const Stmt *S = getItem().getStmtOrNull())
return S;
else
return getItem().getCXXCtorInitializer();
}
public:
explicit ConstructedObjectKey(const ConstructionContextItem &Item,
const LocationContext *LC)
: Impl(Item, LC) {}
const ConstructionContextItem &getItem() const { return Impl.first; }
const LocationContext *getLocationContext() const { return Impl.second; }
ASTContext &getASTContext() const {
return getLocationContext()->getDecl()->getASTContext();
}
void printJson(llvm::raw_ostream &Out, PrinterHelper *Helper,
PrintingPolicy &PP) const {
const Stmt *S = getItem().getStmtOrNull();
const CXXCtorInitializer *I = nullptr;
if (!S)
I = getItem().getCXXCtorInitializer();
if (S)
Out << "\"stmt_id\": " << S->getID(getASTContext());
else
Out << "\"init_id\": " << I->getID(getASTContext());
// Kind
Out << ", \"kind\": \"" << getItem().getKindAsString()
<< "\", \"argument_index\": ";
if (getItem().getKind() == ConstructionContextItem::ArgumentKind)
Out << getItem().getIndex();
else
Out << "null";
// Pretty-print
Out << ", \"pretty\": ";
if (S) {
S->printJson(Out, Helper, PP, /*AddQuotes=*/true);
} else {
Out << '\"' << I->getAnyMember()->getDeclName() << '\"';
}
}
void Profile(llvm::FoldingSetNodeID &ID) const {
ID.Add(Impl.first);
ID.AddPointer(Impl.second);
}
bool operator==(const ConstructedObjectKey &RHS) const {
return Impl == RHS.Impl;
}
bool operator<(const ConstructedObjectKey &RHS) const {
return Impl < RHS.Impl;
}
};
} // namespace
typedef llvm::ImmutableMap<ConstructedObjectKey, SVal>
ObjectsUnderConstructionMap;
REGISTER_TRAIT_WITH_PROGRAMSTATE(ObjectsUnderConstruction,
ObjectsUnderConstructionMap)
//===----------------------------------------------------------------------===//
// Engine construction and deletion.
//===----------------------------------------------------------------------===//
static const char* TagProviderName = "ExprEngine";
ExprEngine::ExprEngine(cross_tu::CrossTranslationUnitContext &CTU,
AnalysisManager &mgr,
SetOfConstDecls *VisitedCalleesIn,
FunctionSummariesTy *FS,
InliningModes HowToInlineIn)
: CTU(CTU), AMgr(mgr),
AnalysisDeclContexts(mgr.getAnalysisDeclContextManager()),
Engine(*this, FS, mgr.getAnalyzerOptions()), G(Engine.getGraph()),
StateMgr(getContext(), mgr.getStoreManagerCreator(),
mgr.getConstraintManagerCreator(), G.getAllocator(),
this),
SymMgr(StateMgr.getSymbolManager()),
MRMgr(StateMgr.getRegionManager()),
svalBuilder(StateMgr.getSValBuilder()),
ObjCNoRet(mgr.getASTContext()),
BR(mgr, *this),
VisitedCallees(VisitedCalleesIn),
HowToInline(HowToInlineIn)
{
unsigned TrimInterval = mgr.options.GraphTrimInterval;
if (TrimInterval != 0) {
// Enable eager node reclamation when constructing the ExplodedGraph.
G.enableNodeReclamation(TrimInterval);
}
}
//===----------------------------------------------------------------------===//
// Utility methods.
//===----------------------------------------------------------------------===//
ProgramStateRef ExprEngine::getInitialState(const LocationContext *InitLoc) {
ProgramStateRef state = StateMgr.getInitialState(InitLoc);
const Decl *D = InitLoc->getDecl();
// Preconditions.
// FIXME: It would be nice if we had a more general mechanism to add
// such preconditions. Some day.
do {
if (const auto *FD = dyn_cast<FunctionDecl>(D)) {
// Precondition: the first argument of 'main' is an integer guaranteed
// to be > 0.
const IdentifierInfo *II = FD->getIdentifier();
if (!II || !(II->getName() == "main" && FD->getNumParams() > 0))
break;
const ParmVarDecl *PD = FD->getParamDecl(0);
QualType T = PD->getType();
const auto *BT = dyn_cast<BuiltinType>(T);
if (!BT || !BT->isInteger())
break;
const MemRegion *R = state->getRegion(PD, InitLoc);
if (!R)
break;
SVal V = state->getSVal(loc::MemRegionVal(R));
SVal Constraint_untested = evalBinOp(state, BO_GT, V,
svalBuilder.makeZeroVal(T),
svalBuilder.getConditionType());
Optional<DefinedOrUnknownSVal> Constraint =
Constraint_untested.getAs<DefinedOrUnknownSVal>();
if (!Constraint)
break;
if (ProgramStateRef newState = state->assume(*Constraint, true))
state = newState;
}
break;
}
while (false);
if (const auto *MD = dyn_cast<ObjCMethodDecl>(D)) {
// Precondition: 'self' is always non-null upon entry to an Objective-C
// method.
const ImplicitParamDecl *SelfD = MD->getSelfDecl();
const MemRegion *R = state->getRegion(SelfD, InitLoc);
SVal V = state->getSVal(loc::MemRegionVal(R));
if (Optional<Loc> LV = V.getAs<Loc>()) {
// Assume that the pointer value in 'self' is non-null.
state = state->assume(*LV, true);
assert(state && "'self' cannot be null");
}
}
if (const auto *MD = dyn_cast<CXXMethodDecl>(D)) {
if (!MD->isStatic()) {
// Precondition: 'this' is always non-null upon entry to the
// top-level function. This is our starting assumption for
// analyzing an "open" program.
const StackFrameContext *SFC = InitLoc->getStackFrame();
if (SFC->getParent() == nullptr) {
loc::MemRegionVal L = svalBuilder.getCXXThis(MD, SFC);
SVal V = state->getSVal(L);
if (Optional<Loc> LV = V.getAs<Loc>()) {
state = state->assume(*LV, true);
assert(state && "'this' cannot be null");
}
}
}
}
return state;
}
ProgramStateRef ExprEngine::createTemporaryRegionIfNeeded(
ProgramStateRef State, const LocationContext *LC,
const Expr *InitWithAdjustments, const Expr *Result,
const SubRegion **OutRegionWithAdjustments) {
// FIXME: This function is a hack that works around the quirky AST
// we're often having with respect to C++ temporaries. If only we modelled
// the actual execution order of statements properly in the CFG,
// all the hassle with adjustments would not be necessary,
// and perhaps the whole function would be removed.
SVal InitValWithAdjustments = State->getSVal(InitWithAdjustments, LC);
if (!Result) {
// If we don't have an explicit result expression, we're in "if needed"
// mode. Only create a region if the current value is a NonLoc.
if (!InitValWithAdjustments.getAs<NonLoc>()) {
if (OutRegionWithAdjustments)
*OutRegionWithAdjustments = nullptr;
return State;
}
Result = InitWithAdjustments;
} else {
// We need to create a region no matter what. For sanity, make sure we don't
// try to stuff a Loc into a non-pointer temporary region.
assert(!InitValWithAdjustments.getAs<Loc>() ||
Loc::isLocType(Result->getType()) ||
Result->getType()->isMemberPointerType());
}
ProgramStateManager &StateMgr = State->getStateManager();
MemRegionManager &MRMgr = StateMgr.getRegionManager();
StoreManager &StoreMgr = StateMgr.getStoreManager();
// MaterializeTemporaryExpr may appear out of place, after a few field and
// base-class accesses have been made to the object, even though semantically
// it is the whole object that gets materialized and lifetime-extended.
//
// For example:
//
// `-MaterializeTemporaryExpr
// `-MemberExpr
// `-CXXTemporaryObjectExpr
//
// instead of the more natural
//
// `-MemberExpr
// `-MaterializeTemporaryExpr
// `-CXXTemporaryObjectExpr
//
// Use the usual methods for obtaining the expression of the base object,
// and record the adjustments that we need to make to obtain the sub-object
// that the whole expression 'Ex' refers to. This trick is usual,
// in the sense that CodeGen takes a similar route.
SmallVector<const Expr *, 2> CommaLHSs;
SmallVector<SubobjectAdjustment, 2> Adjustments;
const Expr *Init = InitWithAdjustments->skipRValueSubobjectAdjustments(
CommaLHSs, Adjustments);
// Take the region for Init, i.e. for the whole object. If we do not remember
// the region in which the object originally was constructed, come up with
// a new temporary region out of thin air and copy the contents of the object
// (which are currently present in the Environment, because Init is an rvalue)
// into that region. This is not correct, but it is better than nothing.
const TypedValueRegion *TR = nullptr;
if (const auto *MT = dyn_cast<MaterializeTemporaryExpr>(Result)) {
if (Optional<SVal> V = getObjectUnderConstruction(State, MT, LC)) {
State = finishObjectConstruction(State, MT, LC);
State = State->BindExpr(Result, LC, *V);
return State;
} else {
StorageDuration SD = MT->getStorageDuration();
// If this object is bound to a reference with static storage duration, we
// put it in a different region to prevent "address leakage" warnings.
if (SD == SD_Static || SD == SD_Thread) {
TR = MRMgr.getCXXStaticTempObjectRegion(Init);
} else {
TR = MRMgr.getCXXTempObjectRegion(Init, LC);
}
}
} else {
TR = MRMgr.getCXXTempObjectRegion(Init, LC);
}
SVal Reg = loc::MemRegionVal(TR);
SVal BaseReg = Reg;
// Make the necessary adjustments to obtain the sub-object.
for (const SubobjectAdjustment &Adj : llvm::reverse(Adjustments)) {
switch (Adj.Kind) {
case SubobjectAdjustment::DerivedToBaseAdjustment:
Reg = StoreMgr.evalDerivedToBase(Reg, Adj.DerivedToBase.BasePath);
break;
case SubobjectAdjustment::FieldAdjustment:
Reg = StoreMgr.getLValueField(Adj.Field, Reg);
break;
case SubobjectAdjustment::MemberPointerAdjustment:
// FIXME: Unimplemented.
State = State->invalidateRegions(Reg, InitWithAdjustments,
currBldrCtx->blockCount(), LC, true,
nullptr, nullptr, nullptr);
return State;
}
}
// What remains is to copy the value of the object to the new region.
// FIXME: In other words, what we should always do is copy value of the
// Init expression (which corresponds to the bigger object) to the whole
// temporary region TR. However, this value is often no longer present
// in the Environment. If it has disappeared, we instead invalidate TR.
// Still, what we can do is assign the value of expression Ex (which
// corresponds to the sub-object) to the TR's sub-region Reg. At least,
// values inside Reg would be correct.
SVal InitVal = State->getSVal(Init, LC);
if (InitVal.isUnknown()) {
InitVal = getSValBuilder().conjureSymbolVal(Result, LC, Init->getType(),
currBldrCtx->blockCount());
State = State->bindLoc(BaseReg.castAs<Loc>(), InitVal, LC, false);
// Then we'd need to take the value that certainly exists and bind it
// over.
if (InitValWithAdjustments.isUnknown()) {
// Try to recover some path sensitivity in case we couldn't
// compute the value.
InitValWithAdjustments = getSValBuilder().conjureSymbolVal(
Result, LC, InitWithAdjustments->getType(),
currBldrCtx->blockCount());
}
State =
State->bindLoc(Reg.castAs<Loc>(), InitValWithAdjustments, LC, false);
} else {
State = State->bindLoc(BaseReg.castAs<Loc>(), InitVal, LC, false);
}
// The result expression would now point to the correct sub-region of the
// newly created temporary region. Do this last in order to getSVal of Init
// correctly in case (Result == Init).
if (Result->isGLValue()) {
State = State->BindExpr(Result, LC, Reg);
} else {
State = State->BindExpr(Result, LC, InitValWithAdjustments);
}
// Notify checkers once for two bindLoc()s.
State = processRegionChange(State, TR, LC);
if (OutRegionWithAdjustments)
*OutRegionWithAdjustments = cast<SubRegion>(Reg.getAsRegion());
return State;
}
ProgramStateRef
ExprEngine::addObjectUnderConstruction(ProgramStateRef State,
const ConstructionContextItem &Item,
const LocationContext *LC, SVal V) {
ConstructedObjectKey Key(Item, LC->getStackFrame());
// FIXME: Currently the state might already contain the marker due to
// incorrect handling of temporaries bound to default parameters.
assert(!State->get<ObjectsUnderConstruction>(Key) ||
Key.getItem().getKind() ==
ConstructionContextItem::TemporaryDestructorKind);
return State->set<ObjectsUnderConstruction>(Key, V);
}
Optional<SVal>
ExprEngine::getObjectUnderConstruction(ProgramStateRef State,
const ConstructionContextItem &Item,
const LocationContext *LC) {
ConstructedObjectKey Key(Item, LC->getStackFrame());
return Optional<SVal>::create(State->get<ObjectsUnderConstruction>(Key));
}
ProgramStateRef
ExprEngine::finishObjectConstruction(ProgramStateRef State,
const ConstructionContextItem &Item,
const LocationContext *LC) {
ConstructedObjectKey Key(Item, LC->getStackFrame());
assert(State->contains<ObjectsUnderConstruction>(Key));
return State->remove<ObjectsUnderConstruction>(Key);
}
ProgramStateRef ExprEngine::elideDestructor(ProgramStateRef State,
const CXXBindTemporaryExpr *BTE,
const LocationContext *LC) {
ConstructedObjectKey Key({BTE, /*IsElided=*/true}, LC);
// FIXME: Currently the state might already contain the marker due to
// incorrect handling of temporaries bound to default parameters.
return State->set<ObjectsUnderConstruction>(Key, UnknownVal());
}
ProgramStateRef
ExprEngine::cleanupElidedDestructor(ProgramStateRef State,
const CXXBindTemporaryExpr *BTE,
const LocationContext *LC) {
ConstructedObjectKey Key({BTE, /*IsElided=*/true}, LC);
assert(State->contains<ObjectsUnderConstruction>(Key));
return State->remove<ObjectsUnderConstruction>(Key);
}
bool ExprEngine::isDestructorElided(ProgramStateRef State,
const CXXBindTemporaryExpr *BTE,
const LocationContext *LC) {
ConstructedObjectKey Key({BTE, /*IsElided=*/true}, LC);
return State->contains<ObjectsUnderConstruction>(Key);
}
bool ExprEngine::areAllObjectsFullyConstructed(ProgramStateRef State,
const LocationContext *FromLC,
const LocationContext *ToLC) {
const LocationContext *LC = FromLC;
while (LC != ToLC) {
assert(LC && "ToLC must be a parent of FromLC!");
for (auto I : State->get<ObjectsUnderConstruction>())
if (I.first.getLocationContext() == LC)
return false;
LC = LC->getParent();
}
return true;
}
//===----------------------------------------------------------------------===//
// Top-level transfer function logic (Dispatcher).
//===----------------------------------------------------------------------===//
/// evalAssume - Called by ConstraintManager. Used to call checker-specific
/// logic for handling assumptions on symbolic values.
ProgramStateRef ExprEngine::processAssume(ProgramStateRef state,
SVal cond, bool assumption) {
return getCheckerManager().runCheckersForEvalAssume(state, cond, assumption);
}
ProgramStateRef
ExprEngine::processRegionChanges(ProgramStateRef state,
const InvalidatedSymbols *invalidated,
ArrayRef<const MemRegion *> Explicits,
ArrayRef<const MemRegion *> Regions,
const LocationContext *LCtx,
const CallEvent *Call) {
return getCheckerManager().runCheckersForRegionChanges(state, invalidated,
Explicits, Regions,
LCtx, Call);
}
static void
printObjectsUnderConstructionJson(raw_ostream &Out, ProgramStateRef State,
const char *NL, const LocationContext *LCtx,
unsigned int Space = 0, bool IsDot = false) {
PrintingPolicy PP =
LCtx->getAnalysisDeclContext()->getASTContext().getPrintingPolicy();
++Space;
bool HasItem = false;
// Store the last key.
const ConstructedObjectKey *LastKey = nullptr;
for (const auto &I : State->get<ObjectsUnderConstruction>()) {
const ConstructedObjectKey &Key = I.first;
if (Key.getLocationContext() != LCtx)
continue;
if (!HasItem) {
Out << "[" << NL;
HasItem = true;
}
LastKey = &Key;
}
for (const auto &I : State->get<ObjectsUnderConstruction>()) {
const ConstructedObjectKey &Key = I.first;
SVal Value = I.second;
if (Key.getLocationContext() != LCtx)
continue;
Indent(Out, Space, IsDot) << "{ ";
Key.printJson(Out, nullptr, PP);
Out << ", \"value\": \"" << Value << "\" }";
if (&Key != LastKey)
Out << ',';
Out << NL;
}
if (HasItem)
Indent(Out, --Space, IsDot) << ']'; // End of "location_context".
else {
Out << "null ";
}
}
void ExprEngine::printJson(raw_ostream &Out, ProgramStateRef State,
const LocationContext *LCtx, const char *NL,
unsigned int Space, bool IsDot) const {
Indent(Out, Space, IsDot) << "\"constructing_objects\": ";
if (LCtx && !State->get<ObjectsUnderConstruction>().isEmpty()) {
++Space;
Out << '[' << NL;
LCtx->printJson(Out, NL, Space, IsDot, [&](const LocationContext *LC) {
printObjectsUnderConstructionJson(Out, State, NL, LC, Space, IsDot);
});
--Space;
Indent(Out, Space, IsDot) << "]," << NL; // End of "constructing_objects".
} else {
Out << "null," << NL;
}
getCheckerManager().runCheckersForPrintStateJson(Out, State, NL, Space,
IsDot);
}
void ExprEngine::processEndWorklist() {
getCheckerManager().runCheckersForEndAnalysis(G, BR, *this);
}
void ExprEngine::processCFGElement(const CFGElement E, ExplodedNode *Pred,
unsigned StmtIdx, NodeBuilderContext *Ctx) {
PrettyStackTraceLocationContext CrashInfo(Pred->getLocationContext());
currStmtIdx = StmtIdx;
currBldrCtx = Ctx;
switch (E.getKind()) {
case CFGElement::Statement:
case CFGElement::Constructor:
case CFGElement::CXXRecordTypedCall:
ProcessStmt(E.castAs<CFGStmt>().getStmt(), Pred);
return;
case CFGElement::Initializer:
ProcessInitializer(E.castAs<CFGInitializer>(), Pred);
return;
case CFGElement::NewAllocator:
ProcessNewAllocator(E.castAs<CFGNewAllocator>().getAllocatorExpr(),
Pred);
return;
case CFGElement::AutomaticObjectDtor:
case CFGElement::DeleteDtor:
case CFGElement::BaseDtor:
case CFGElement::MemberDtor:
case CFGElement::TemporaryDtor:
ProcessImplicitDtor(E.castAs<CFGImplicitDtor>(), Pred);
return;
case CFGElement::LoopExit:
ProcessLoopExit(E.castAs<CFGLoopExit>().getLoopStmt(), Pred);
return;
case CFGElement::LifetimeEnds:
case CFGElement::ScopeBegin:
case CFGElement::ScopeEnd:
return;
}
}
static bool shouldRemoveDeadBindings(AnalysisManager &AMgr,
const Stmt *S,
const ExplodedNode *Pred,
const LocationContext *LC) {
// Are we never purging state values?
if (AMgr.options.AnalysisPurgeOpt == PurgeNone)
return false;
// Is this the beginning of a basic block?
if (Pred->getLocation().getAs<BlockEntrance>())
return true;
// Is this on a non-expression?
if (!isa<Expr>(S))
return true;
// Run before processing a call.
if (CallEvent::isCallStmt(S))
return true;
// Is this an expression that is consumed by another expression? If so,
// postpone cleaning out the state.
ParentMap &PM = LC->getAnalysisDeclContext()->getParentMap();
return !PM.isConsumedExpr(cast<Expr>(S));
}
void ExprEngine::removeDead(ExplodedNode *Pred, ExplodedNodeSet &Out,
const Stmt *ReferenceStmt,
const LocationContext *LC,
const Stmt *DiagnosticStmt,
ProgramPoint::Kind K) {
assert((K == ProgramPoint::PreStmtPurgeDeadSymbolsKind ||
ReferenceStmt == nullptr || isa<ReturnStmt>(ReferenceStmt))
&& "PostStmt is not generally supported by the SymbolReaper yet");
assert(LC && "Must pass the current (or expiring) LocationContext");
if (!DiagnosticStmt) {
DiagnosticStmt = ReferenceStmt;
assert(DiagnosticStmt && "Required for clearing a LocationContext");
}
NumRemoveDeadBindings++;
ProgramStateRef CleanedState = Pred->getState();
// LC is the location context being destroyed, but SymbolReaper wants a
// location context that is still live. (If this is the top-level stack
// frame, this will be null.)
if (!ReferenceStmt) {
assert(K == ProgramPoint::PostStmtPurgeDeadSymbolsKind &&
"Use PostStmtPurgeDeadSymbolsKind for clearing a LocationContext");
LC = LC->getParent();
}
const StackFrameContext *SFC = LC ? LC->getStackFrame() : nullptr;
SymbolReaper SymReaper(SFC, ReferenceStmt, SymMgr, getStoreManager());
for (auto I : CleanedState->get<ObjectsUnderConstruction>()) {
if (SymbolRef Sym = I.second.getAsSymbol())
SymReaper.markLive(Sym);
if (const MemRegion *MR = I.second.getAsRegion())
SymReaper.markLive(MR);
}
getCheckerManager().runCheckersForLiveSymbols(CleanedState, SymReaper);
// Create a state in which dead bindings are removed from the environment
// and the store. TODO: The function should just return new env and store,
// not a new state.
CleanedState = StateMgr.removeDeadBindingsFromEnvironmentAndStore(
CleanedState, SFC, SymReaper);
// Process any special transfer function for dead symbols.
// A tag to track convenience transitions, which can be removed at cleanup.
static SimpleProgramPointTag cleanupTag(TagProviderName, "Clean Node");
// Call checkers with the non-cleaned state so that they could query the
// values of the soon to be dead symbols.
ExplodedNodeSet CheckedSet;
getCheckerManager().runCheckersForDeadSymbols(CheckedSet, Pred, SymReaper,
DiagnosticStmt, *this, K);
// For each node in CheckedSet, generate CleanedNodes that have the
// environment, the store, and the constraints cleaned up but have the
// user-supplied states as the predecessors.
StmtNodeBuilder Bldr(CheckedSet, Out, *currBldrCtx);
for (const auto I : CheckedSet) {
ProgramStateRef CheckerState = I->getState();
// The constraint manager has not been cleaned up yet, so clean up now.
CheckerState =
getConstraintManager().removeDeadBindings(CheckerState, SymReaper);
assert(StateMgr.haveEqualEnvironments(CheckerState, Pred->getState()) &&
"Checkers are not allowed to modify the Environment as a part of "
"checkDeadSymbols processing.");
assert(StateMgr.haveEqualStores(CheckerState, Pred->getState()) &&
"Checkers are not allowed to modify the Store as a part of "
"checkDeadSymbols processing.");
// Create a state based on CleanedState with CheckerState GDM and
// generate a transition to that state.
ProgramStateRef CleanedCheckerSt =
StateMgr.getPersistentStateWithGDM(CleanedState, CheckerState);
Bldr.generateNode(DiagnosticStmt, I, CleanedCheckerSt, &cleanupTag, K);
}
}
void ExprEngine::ProcessStmt(const Stmt *currStmt, ExplodedNode *Pred) {
// Reclaim any unnecessary nodes in the ExplodedGraph.
G.reclaimRecentlyAllocatedNodes();
PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),
currStmt->getBeginLoc(),
"Error evaluating statement");
// Remove dead bindings and symbols.
ExplodedNodeSet CleanedStates;
if (shouldRemoveDeadBindings(AMgr, currStmt, Pred,
Pred->getLocationContext())) {
removeDead(Pred, CleanedStates, currStmt,
Pred->getLocationContext());
} else
CleanedStates.Add(Pred);
// Visit the statement.
ExplodedNodeSet Dst;
for (const auto I : CleanedStates) {
ExplodedNodeSet DstI;
// Visit the statement.
Visit(currStmt, I, DstI);
Dst.insert(DstI);
}
// Enqueue the new nodes onto the work list.
Engine.enqueue(Dst, currBldrCtx->getBlock(), currStmtIdx);
}
void ExprEngine::ProcessLoopExit(const Stmt* S, ExplodedNode *Pred) {
PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),
S->getBeginLoc(),
"Error evaluating end of the loop");
ExplodedNodeSet Dst;
Dst.Add(Pred);
NodeBuilder Bldr(Pred, Dst, *currBldrCtx);
ProgramStateRef NewState = Pred->getState();
if(AMgr.options.ShouldUnrollLoops)
NewState = processLoopEnd(S, NewState);
LoopExit PP(S, Pred->getLocationContext());
Bldr.generateNode(PP, NewState, Pred);
// Enqueue the new nodes onto the work list.
Engine.enqueue(Dst, currBldrCtx->getBlock(), currStmtIdx);
}
void ExprEngine::ProcessInitializer(const CFGInitializer CFGInit,
ExplodedNode *Pred) {
const CXXCtorInitializer *BMI = CFGInit.getInitializer();
const Expr *Init = BMI->getInit()->IgnoreImplicit();
const LocationContext *LC = Pred->getLocationContext();
PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),
BMI->getSourceLocation(),
"Error evaluating initializer");
// We don't clean up dead bindings here.
const auto *stackFrame = cast<StackFrameContext>(Pred->getLocationContext());
const auto *decl = cast<CXXConstructorDecl>(stackFrame->getDecl());
ProgramStateRef State = Pred->getState();
SVal thisVal = State->getSVal(svalBuilder.getCXXThis(decl, stackFrame));
ExplodedNodeSet Tmp;
SVal FieldLoc;
// Evaluate the initializer, if necessary
if (BMI->isAnyMemberInitializer()) {
// Constructors build the object directly in the field,
// but non-objects must be copied in from the initializer.
if (getObjectUnderConstruction(State, BMI, LC)) {
// The field was directly constructed, so there is no need to bind.
// But we still need to stop tracking the object under construction.
State = finishObjectConstruction(State, BMI, LC);
NodeBuilder Bldr(Pred, Tmp, *currBldrCtx);
PostStore PS(Init, LC, /*Loc*/ nullptr, /*tag*/ nullptr);
Bldr.generateNode(PS, State, Pred);
} else {
const ValueDecl *Field;
if (BMI->isIndirectMemberInitializer()) {
Field = BMI->getIndirectMember();
FieldLoc = State->getLValue(BMI->getIndirectMember(), thisVal);
} else {
Field = BMI->getMember();
FieldLoc = State->getLValue(BMI->getMember(), thisVal);
}
SVal InitVal;
if (Init->getType()->isArrayType()) {
// Handle arrays of trivial type. We can represent this with a
// primitive load/copy from the base array region.
const ArraySubscriptExpr *ASE;
while ((ASE = dyn_cast<ArraySubscriptExpr>(Init)))
Init = ASE->getBase()->IgnoreImplicit();
SVal LValue = State->getSVal(Init, stackFrame);
if (!Field->getType()->isReferenceType())
if (Optional<Loc> LValueLoc = LValue.getAs<Loc>())
InitVal = State->getSVal(*LValueLoc);
// If we fail to get the value for some reason, use a symbolic value.
if (InitVal.isUnknownOrUndef()) {
SValBuilder &SVB = getSValBuilder();
InitVal = SVB.conjureSymbolVal(BMI->getInit(), stackFrame,
Field->getType(),
currBldrCtx->blockCount());
}
} else {
InitVal = State->getSVal(BMI->getInit(), stackFrame);
}
PostInitializer PP(BMI, FieldLoc.getAsRegion(), stackFrame);
evalBind(Tmp, Init, Pred, FieldLoc, InitVal, /*isInit=*/true, &PP);
}
} else {
assert(BMI->isBaseInitializer() || BMI->isDelegatingInitializer());
Tmp.insert(Pred);
// We already did all the work when visiting the CXXConstructExpr.
}
// Construct PostInitializer nodes whether the state changed or not,
// so that the diagnostics don't get confused.
PostInitializer PP(BMI, FieldLoc.getAsRegion(), stackFrame);
ExplodedNodeSet Dst;
NodeBuilder Bldr(Tmp, Dst, *currBldrCtx);
for (const auto I : Tmp) {
ProgramStateRef State = I->getState();
Bldr.generateNode(PP, State, I);
}
// Enqueue the new nodes onto the work list.
Engine.enqueue(Dst, currBldrCtx->getBlock(), currStmtIdx);
}
void ExprEngine::ProcessImplicitDtor(const CFGImplicitDtor D,
ExplodedNode *Pred) {
ExplodedNodeSet Dst;
switch (D.getKind()) {
case CFGElement::AutomaticObjectDtor:
ProcessAutomaticObjDtor(D.castAs<CFGAutomaticObjDtor>(), Pred, Dst);
break;
case CFGElement::BaseDtor:
ProcessBaseDtor(D.castAs<CFGBaseDtor>(), Pred, Dst);
break;
case CFGElement::MemberDtor:
ProcessMemberDtor(D.castAs<CFGMemberDtor>(), Pred, Dst);
break;
case CFGElement::TemporaryDtor:
ProcessTemporaryDtor(D.castAs<CFGTemporaryDtor>(), Pred, Dst);
break;
case CFGElement::DeleteDtor:
ProcessDeleteDtor(D.castAs<CFGDeleteDtor>(), Pred, Dst);
break;
default:
llvm_unreachable("Unexpected dtor kind.");
}
// Enqueue the new nodes onto the work list.
Engine.enqueue(Dst, currBldrCtx->getBlock(), currStmtIdx);
}
void ExprEngine::ProcessNewAllocator(const CXXNewExpr *NE,
ExplodedNode *Pred) {
ExplodedNodeSet Dst;
AnalysisManager &AMgr = getAnalysisManager();
AnalyzerOptions &Opts = AMgr.options;
// TODO: We're not evaluating allocators for all cases just yet as
// we're not handling the return value correctly, which causes false
// positives when the alpha.cplusplus.NewDeleteLeaks check is on.
if (Opts.MayInlineCXXAllocator)
VisitCXXNewAllocatorCall(NE, Pred, Dst);
else {
NodeBuilder Bldr(Pred, Dst, *currBldrCtx);
const LocationContext *LCtx = Pred->getLocationContext();
PostImplicitCall PP(NE->getOperatorNew(), NE->getBeginLoc(), LCtx);
Bldr.generateNode(PP, Pred->getState(), Pred);
}
Engine.enqueue(Dst, currBldrCtx->getBlock(), currStmtIdx);
}
void ExprEngine::ProcessAutomaticObjDtor(const CFGAutomaticObjDtor Dtor,
ExplodedNode *Pred,
ExplodedNodeSet &Dst) {
const VarDecl *varDecl = Dtor.getVarDecl();
QualType varType = varDecl->getType();
ProgramStateRef state = Pred->getState();
SVal dest = state->getLValue(varDecl, Pred->getLocationContext());
const MemRegion *Region = dest.castAs<loc::MemRegionVal>().getRegion();
if (varType->isReferenceType()) {
const MemRegion *ValueRegion = state->getSVal(Region).getAsRegion();
if (!ValueRegion) {
// FIXME: This should not happen. The language guarantees a presence
// of a valid initializer here, so the reference shall not be undefined.
// It seems that we're calling destructors over variables that
// were not initialized yet.
return;
}
Region = ValueRegion->getBaseRegion();
varType = cast<TypedValueRegion>(Region)->getValueType();
}
// FIXME: We need to run the same destructor on every element of the array.
// This workaround will just run the first destructor (which will still
// invalidate the entire array).
EvalCallOptions CallOpts;
Region = makeZeroElementRegion(state, loc::MemRegionVal(Region), varType,
CallOpts.IsArrayCtorOrDtor).getAsRegion();
VisitCXXDestructor(varType, Region, Dtor.getTriggerStmt(),
/*IsBase=*/false, Pred, Dst, CallOpts);
}
void ExprEngine::ProcessDeleteDtor(const CFGDeleteDtor Dtor,
ExplodedNode *Pred,
ExplodedNodeSet &Dst) {
ProgramStateRef State = Pred->getState();
const LocationContext *LCtx = Pred->getLocationContext();
const CXXDeleteExpr *DE = Dtor.getDeleteExpr();
const Stmt *Arg = DE->getArgument();
QualType DTy = DE->getDestroyedType();
SVal ArgVal = State->getSVal(Arg, LCtx);
// If the argument to delete is known to be a null value,
// don't run destructor.
if (State->isNull(ArgVal).isConstrainedTrue()) {
QualType BTy = getContext().getBaseElementType(DTy);
const CXXRecordDecl *RD = BTy->getAsCXXRecordDecl();
const CXXDestructorDecl *Dtor = RD->getDestructor();