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llvm-project/clang/lib/StaticAnalyzer/Core/ExprEngineCXX.cpp

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//===- ExprEngineCXX.cpp - ExprEngine support for C++ -----------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the C++ expression evaluation engine.
//
//===----------------------------------------------------------------------===//
#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/StmtCXX.h"
#include "clang/Basic/PrettyStackTrace.h"
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
using namespace clang;
using namespace ento;
void ExprEngine::CreateCXXTemporaryObject(const MaterializeTemporaryExpr *ME,
ExplodedNode *Pred,
ExplodedNodeSet &Dst) {
StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx);
const Expr *tempExpr = ME->GetTemporaryExpr()->IgnoreParens();
ProgramStateRef state = Pred->getState();
const LocationContext *LCtx = Pred->getLocationContext();
state = createTemporaryRegionIfNeeded(state, LCtx, tempExpr, ME);
Bldr.generateNode(ME, Pred, state);
}
// FIXME: This is the sort of code that should eventually live in a Core
// checker rather than as a special case in ExprEngine.
void ExprEngine::performTrivialCopy(NodeBuilder &Bldr, ExplodedNode *Pred,
const CallEvent &Call) {
SVal ThisVal;
bool AlwaysReturnsLValue;
if (const CXXConstructorCall *Ctor = dyn_cast<CXXConstructorCall>(&Call)) {
assert(Ctor->getDecl()->isTrivial());
assert(Ctor->getDecl()->isCopyOrMoveConstructor());
ThisVal = Ctor->getCXXThisVal();
AlwaysReturnsLValue = false;
} else {
assert(cast<CXXMethodDecl>(Call.getDecl())->isTrivial());
assert(cast<CXXMethodDecl>(Call.getDecl())->getOverloadedOperator() ==
OO_Equal);
ThisVal = cast<CXXInstanceCall>(Call).getCXXThisVal();
AlwaysReturnsLValue = true;
}
const LocationContext *LCtx = Pred->getLocationContext();
ExplodedNodeSet Dst;
Bldr.takeNodes(Pred);
SVal V = Call.getArgSVal(0);
// If the value being copied is not unknown, load from its location to get
// an aggregate rvalue.
if (Optional<Loc> L = V.getAs<Loc>())
V = Pred->getState()->getSVal(*L);
else
assert(V.isUnknown());
const Expr *CallExpr = Call.getOriginExpr();
evalBind(Dst, CallExpr, Pred, ThisVal, V, true);
PostStmt PS(CallExpr, LCtx);
for (ExplodedNodeSet::iterator I = Dst.begin(), E = Dst.end();
I != E; ++I) {
ProgramStateRef State = (*I)->getState();
if (AlwaysReturnsLValue)
State = State->BindExpr(CallExpr, LCtx, ThisVal);
else
State = bindReturnValue(Call, LCtx, State);
Bldr.generateNode(PS, State, *I);
}
}
/// Returns a region representing the first element of a (possibly
/// multi-dimensional) array.
///
/// On return, \p Ty will be set to the base type of the array.
///
/// If the type is not an array type at all, the original value is returned.
static SVal makeZeroElementRegion(ProgramStateRef State, SVal LValue,
QualType &Ty) {
// FIXME: This check is just a temporary workaround, because
// ProcessTemporaryDtor sends us NULL regions. It will not be necessary once
// we can properly process temporary destructors.
if (!LValue.getAsRegion())
return LValue;
SValBuilder &SVB = State->getStateManager().getSValBuilder();
ASTContext &Ctx = SVB.getContext();
while (const ArrayType *AT = Ctx.getAsArrayType(Ty)) {
Ty = AT->getElementType();
LValue = State->getLValue(Ty, SVB.makeZeroArrayIndex(), LValue);
}
return LValue;
}
void ExprEngine::VisitCXXConstructExpr(const CXXConstructExpr *CE,
ExplodedNode *Pred,
ExplodedNodeSet &destNodes) {
const LocationContext *LCtx = Pred->getLocationContext();
ProgramStateRef State = Pred->getState();
const MemRegion *Target = 0;
// FIXME: Handle arrays, which run the same constructor for every element.
// For now, we just run the first constructor (which should still invalidate
// the entire array).
switch (CE->getConstructionKind()) {
case CXXConstructExpr::CK_Complete: {
// See if we're constructing an existing region by looking at the next
// element in the CFG.
const CFGBlock *B = currBldrCtx->getBlock();
if (currStmtIdx + 1 < B->size()) {
CFGElement Next = (*B)[currStmtIdx+1];
// Is this a constructor for a local variable?
if (Optional<CFGStmt> StmtElem = Next.getAs<CFGStmt>()) {
if (const DeclStmt *DS = dyn_cast<DeclStmt>(StmtElem->getStmt())) {
if (const VarDecl *Var = dyn_cast<VarDecl>(DS->getSingleDecl())) {
if (Var->getInit()->IgnoreImplicit() == CE) {
SVal LValue = State->getLValue(Var, LCtx);
QualType Ty = Var->getType();
LValue = makeZeroElementRegion(State, LValue, Ty);
Target = LValue.getAsRegion();
}
}
}
}
// Is this a constructor for a member?
if (Optional<CFGInitializer> InitElem = Next.getAs<CFGInitializer>()) {
const CXXCtorInitializer *Init = InitElem->getInitializer();
assert(Init->isAnyMemberInitializer());
const CXXMethodDecl *CurCtor = cast<CXXMethodDecl>(LCtx->getDecl());
Loc ThisPtr = getSValBuilder().getCXXThis(CurCtor,
LCtx->getCurrentStackFrame());
SVal ThisVal = State->getSVal(ThisPtr);
const ValueDecl *Field;
SVal FieldVal;
if (Init->isIndirectMemberInitializer()) {
Field = Init->getIndirectMember();
FieldVal = State->getLValue(Init->getIndirectMember(), ThisVal);
} else {
Field = Init->getMember();
FieldVal = State->getLValue(Init->getMember(), ThisVal);
}
QualType Ty = Field->getType();
FieldVal = makeZeroElementRegion(State, FieldVal, Ty);
Target = FieldVal.getAsRegion();
}
// FIXME: This will eventually need to handle new-expressions as well.
// Don't forget to update the pre-constructor initialization code below.
}
// If we couldn't find an existing region to construct into, assume we're
// constructing a temporary.
if (!Target) {
MemRegionManager &MRMgr = getSValBuilder().getRegionManager();
Target = MRMgr.getCXXTempObjectRegion(CE, LCtx);
}
break;
}
case CXXConstructExpr::CK_VirtualBase:
// Make sure we are not calling virtual base class initializers twice.
// Only the most-derived object should initialize virtual base classes.
if (const Stmt *Outer = LCtx->getCurrentStackFrame()->getCallSite()) {
const CXXConstructExpr *OuterCtor = dyn_cast<CXXConstructExpr>(Outer);
if (OuterCtor) {
switch (OuterCtor->getConstructionKind()) {
case CXXConstructExpr::CK_NonVirtualBase:
case CXXConstructExpr::CK_VirtualBase:
// Bail out!
destNodes.Add(Pred);
return;
case CXXConstructExpr::CK_Complete:
case CXXConstructExpr::CK_Delegating:
break;
}
}
}
// FALLTHROUGH
case CXXConstructExpr::CK_NonVirtualBase:
case CXXConstructExpr::CK_Delegating: {
const CXXMethodDecl *CurCtor = cast<CXXMethodDecl>(LCtx->getDecl());
Loc ThisPtr = getSValBuilder().getCXXThis(CurCtor,
LCtx->getCurrentStackFrame());
SVal ThisVal = State->getSVal(ThisPtr);
if (CE->getConstructionKind() == CXXConstructExpr::CK_Delegating) {
Target = ThisVal.getAsRegion();
} else {
// Cast to the base type.
bool IsVirtual =
(CE->getConstructionKind() == CXXConstructExpr::CK_VirtualBase);
SVal BaseVal = getStoreManager().evalDerivedToBase(ThisVal, CE->getType(),
IsVirtual);
Target = BaseVal.getAsRegion();
}
break;
}
}
CallEventManager &CEMgr = getStateManager().getCallEventManager();
CallEventRef<CXXConstructorCall> Call =
CEMgr.getCXXConstructorCall(CE, Target, State, LCtx);
ExplodedNodeSet DstPreVisit;
getCheckerManager().runCheckersForPreStmt(DstPreVisit, Pred, CE, *this);
ExplodedNodeSet PreInitialized;
{
StmtNodeBuilder Bldr(DstPreVisit, PreInitialized, *currBldrCtx);
if (CE->requiresZeroInitialization()) {
// Type of the zero doesn't matter.
SVal ZeroVal = svalBuilder.makeZeroVal(getContext().CharTy);
for (ExplodedNodeSet::iterator I = DstPreVisit.begin(),
E = DstPreVisit.end();
I != E; ++I) {
ProgramStateRef State = (*I)->getState();
// FIXME: Once we properly handle constructors in new-expressions, we'll
// need to invalidate the region before setting a default value, to make
// sure there aren't any lingering bindings around. This probably needs
// to happen regardless of whether or not the object is zero-initialized
// to handle random fields of a placement-initialized object picking up
// old bindings. We might only want to do it when we need to, though.
// FIXME: This isn't actually correct for arrays -- we need to zero-
// initialize the entire array, not just the first element -- but our
// handling of arrays everywhere else is weak as well, so this shouldn't
// actually make things worse. Placement new makes this tricky as well,
// since it's then possible to be initializing one part of a multi-
// dimensional array.
State = State->bindDefault(loc::MemRegionVal(Target), ZeroVal);
Bldr.generateNode(CE, *I, State, /*tag=*/0, ProgramPoint::PreStmtKind);
}
}
}
ExplodedNodeSet DstPreCall;
getCheckerManager().runCheckersForPreCall(DstPreCall, PreInitialized,
*Call, *this);
ExplodedNodeSet DstEvaluated;
StmtNodeBuilder Bldr(DstPreCall, DstEvaluated, *currBldrCtx);
bool IsArray = isa<ElementRegion>(Target);
if (CE->getConstructor()->isTrivial() &&
CE->getConstructor()->isCopyOrMoveConstructor() &&
!IsArray) {
// FIXME: Handle other kinds of trivial constructors as well.
for (ExplodedNodeSet::iterator I = DstPreCall.begin(), E = DstPreCall.end();
I != E; ++I)
performTrivialCopy(Bldr, *I, *Call);
} else {
for (ExplodedNodeSet::iterator I = DstPreCall.begin(), E = DstPreCall.end();
I != E; ++I)
defaultEvalCall(Bldr, *I, *Call);
}
ExplodedNodeSet DstPostCall;
getCheckerManager().runCheckersForPostCall(DstPostCall, DstEvaluated,
*Call, *this);
getCheckerManager().runCheckersForPostStmt(destNodes, DstPostCall, CE, *this);
}
void ExprEngine::VisitCXXDestructor(QualType ObjectType,
const MemRegion *Dest,
const Stmt *S,
bool IsBaseDtor,
ExplodedNode *Pred,
ExplodedNodeSet &Dst) {
const LocationContext *LCtx = Pred->getLocationContext();
ProgramStateRef State = Pred->getState();
// 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).
SVal DestVal = UnknownVal();
if (Dest)
DestVal = loc::MemRegionVal(Dest);
DestVal = makeZeroElementRegion(State, DestVal, ObjectType);
Dest = DestVal.getAsRegion();
const CXXRecordDecl *RecordDecl = ObjectType->getAsCXXRecordDecl();
assert(RecordDecl && "Only CXXRecordDecls should have destructors");
const CXXDestructorDecl *DtorDecl = RecordDecl->getDestructor();
CallEventManager &CEMgr = getStateManager().getCallEventManager();
CallEventRef<CXXDestructorCall> Call =
CEMgr.getCXXDestructorCall(DtorDecl, S, Dest, IsBaseDtor, State, LCtx);
PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),
Call->getSourceRange().getBegin(),
"Error evaluating destructor");
ExplodedNodeSet DstPreCall;
getCheckerManager().runCheckersForPreCall(DstPreCall, Pred,
*Call, *this);
ExplodedNodeSet DstInvalidated;
StmtNodeBuilder Bldr(DstPreCall, DstInvalidated, *currBldrCtx);
for (ExplodedNodeSet::iterator I = DstPreCall.begin(), E = DstPreCall.end();
I != E; ++I)
defaultEvalCall(Bldr, *I, *Call);
ExplodedNodeSet DstPostCall;
getCheckerManager().runCheckersForPostCall(Dst, DstInvalidated,
*Call, *this);
}
void ExprEngine::VisitCXXNewExpr(const CXXNewExpr *CNE, ExplodedNode *Pred,
ExplodedNodeSet &Dst) {
// FIXME: Much of this should eventually migrate to CXXAllocatorCall.
// Also, we need to decide how allocators actually work -- they're not
// really part of the CXXNewExpr because they happen BEFORE the
// CXXConstructExpr subexpression. See PR12014 for some discussion.
unsigned blockCount = currBldrCtx->blockCount();
const LocationContext *LCtx = Pred->getLocationContext();
DefinedOrUnknownSVal symVal = UnknownVal();
FunctionDecl *FD = CNE->getOperatorNew();
bool IsStandardGlobalOpNewFunction = false;
if (FD && !isa<CXXMethodDecl>(FD) && !FD->isVariadic()) {
if (FD->getNumParams() == 2) {
QualType T = FD->getParamDecl(1)->getType();
if (const IdentifierInfo *II = T.getBaseTypeIdentifier())
// NoThrow placement new behaves as a standard new.
IsStandardGlobalOpNewFunction = II->getName().equals("nothrow_t");
}
else
// Placement forms are considered non-standard.
IsStandardGlobalOpNewFunction = (FD->getNumParams() == 1);
}
// We assume all standard global 'operator new' functions allocate memory in
// heap. We realize this is an approximation that might not correctly model
// a custom global allocator.
if (IsStandardGlobalOpNewFunction)
symVal = svalBuilder.getConjuredHeapSymbolVal(CNE, LCtx, blockCount);
else
symVal = svalBuilder.conjureSymbolVal(0, CNE, LCtx, CNE->getType(),
blockCount);
ProgramStateRef State = Pred->getState();
CallEventManager &CEMgr = getStateManager().getCallEventManager();
CallEventRef<CXXAllocatorCall> Call =
CEMgr.getCXXAllocatorCall(CNE, State, LCtx);
// Invalidate placement args.
// FIXME: Once we figure out how we want allocators to work,
// we should be using the usual pre-/(default-)eval-/post-call checks here.
State = Call->invalidateRegions(blockCount);
if (!State)
return;
// If this allocation function is not declared as non-throwing, failures
// /must/ be signalled by exceptions, and thus the return value will never be
// NULL. -fno-exceptions does not influence this semantics.
// FIXME: GCC has a -fcheck-new option, which forces it to consider the case
// where new can return NULL. If we end up supporting that option, we can
// consider adding a check for it here.
// C++11 [basic.stc.dynamic.allocation]p3.
if (FD) {
QualType Ty = FD->getType();
if (const FunctionProtoType *ProtoType = Ty->getAs<FunctionProtoType>())
if (!ProtoType->isNothrow(getContext()))
State = State->assume(symVal, true);
}
StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx);
if (CNE->isArray()) {
// FIXME: allocating an array requires simulating the constructors.
// For now, just return a symbolicated region.
const MemRegion *NewReg = symVal.castAs<loc::MemRegionVal>().getRegion();
QualType ObjTy = CNE->getType()->getAs<PointerType>()->getPointeeType();
const ElementRegion *EleReg =
getStoreManager().GetElementZeroRegion(NewReg, ObjTy);
State = State->BindExpr(CNE, Pred->getLocationContext(),
loc::MemRegionVal(EleReg));
Bldr.generateNode(CNE, Pred, State);
return;
}
// FIXME: Once we have proper support for CXXConstructExprs inside
// CXXNewExpr, we need to make sure that the constructed object is not
// immediately invalidated here. (The placement call should happen before
// the constructor call anyway.)
SVal Result = symVal;
if (FD && FD->isReservedGlobalPlacementOperator()) {
// Non-array placement new should always return the placement location.
SVal PlacementLoc = State->getSVal(CNE->getPlacementArg(0), LCtx);
Result = svalBuilder.evalCast(PlacementLoc, CNE->getType(),
CNE->getPlacementArg(0)->getType());
}
// Bind the address of the object, then check to see if we cached out.
State = State->BindExpr(CNE, LCtx, Result);
ExplodedNode *NewN = Bldr.generateNode(CNE, Pred, State);
if (!NewN)
return;
// If the type is not a record, we won't have a CXXConstructExpr as an
// initializer. Copy the value over.
if (const Expr *Init = CNE->getInitializer()) {
if (!isa<CXXConstructExpr>(Init)) {
assert(Bldr.getResults().size() == 1);
Bldr.takeNodes(NewN);
evalBind(Dst, CNE, NewN, Result, State->getSVal(Init, LCtx),
/*FirstInit=*/IsStandardGlobalOpNewFunction);
}
}
}
void ExprEngine::VisitCXXDeleteExpr(const CXXDeleteExpr *CDE,
ExplodedNode *Pred, ExplodedNodeSet &Dst) {
StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx);
ProgramStateRef state = Pred->getState();
Bldr.generateNode(CDE, Pred, state);
}
void ExprEngine::VisitCXXCatchStmt(const CXXCatchStmt *CS,
ExplodedNode *Pred,
ExplodedNodeSet &Dst) {
const VarDecl *VD = CS->getExceptionDecl();
if (!VD) {
Dst.Add(Pred);
return;
}
const LocationContext *LCtx = Pred->getLocationContext();
SVal V = svalBuilder.conjureSymbolVal(CS, LCtx, VD->getType(),
currBldrCtx->blockCount());
ProgramStateRef state = Pred->getState();
state = state->bindLoc(state->getLValue(VD, LCtx), V);
StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx);
Bldr.generateNode(CS, Pred, state);
}
void ExprEngine::VisitCXXThisExpr(const CXXThisExpr *TE, ExplodedNode *Pred,
ExplodedNodeSet &Dst) {
StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx);
// Get the this object region from StoreManager.
const LocationContext *LCtx = Pred->getLocationContext();
const MemRegion *R =
svalBuilder.getRegionManager().getCXXThisRegion(
getContext().getCanonicalType(TE->getType()),
LCtx);
ProgramStateRef state = Pred->getState();
SVal V = state->getSVal(loc::MemRegionVal(R));
Bldr.generateNode(TE, Pred, state->BindExpr(TE, LCtx, V));
}
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