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//=-- ExprEngineObjC.cpp - ExprEngine support for Objective-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 ExprEngine's support for Objective-C expressions.
#include "clang/AST/StmtObjC.h"
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
using namespace clang;
using namespace ento;
void ExprEngine::VisitLvalObjCIvarRefExpr(const ObjCIvarRefExpr *Ex,
ExplodedNode *Pred,
ExplodedNodeSet &Dst) {
ProgramStateRef state = Pred->getState();
const LocationContext *LCtx = Pred->getLocationContext();
SVal baseVal = state->getSVal(Ex->getBase(), LCtx);
SVal location = state->getLValue(Ex->getDecl(), baseVal);
ExplodedNodeSet dstIvar;
StmtNodeBuilder Bldr(Pred, dstIvar, *currentBuilderContext);
Bldr.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, location));
// Perform the post-condition check of the ObjCIvarRefExpr and store
// the created nodes in 'Dst'.
getCheckerManager().runCheckersForPostStmt(Dst, dstIvar, Ex, *this);
void ExprEngine::VisitObjCAtSynchronizedStmt(const ObjCAtSynchronizedStmt *S,
ExplodedNode *Pred,
ExplodedNodeSet &Dst) {
getCheckerManager().runCheckersForPreStmt(Dst, Pred, S, *this);
void ExprEngine::VisitObjCForCollectionStmt(const ObjCForCollectionStmt *S,
ExplodedNode *Pred,
ExplodedNodeSet &Dst) {
// ObjCForCollectionStmts are processed in two places. This method
// handles the case where an ObjCForCollectionStmt* occurs as one of the
// statements within a basic block. This transfer function does two things:
// (1) binds the next container value to 'element'. This creates a new
// node in the ExplodedGraph.
// (2) binds the value 0/1 to the ObjCForCollectionStmt* itself, indicating
// whether or not the container has any more elements. This value
// will be tested in ProcessBranch. We need to explicitly bind
// this value because a container can contain nil elements.
// FIXME: Eventually this logic should actually do dispatches to
// 'countByEnumeratingWithState:objects:count:' (NSFastEnumeration).
// This will require simulating a temporary NSFastEnumerationState, either
// through an SVal or through the use of MemRegions. This value can
// be affixed to the ObjCForCollectionStmt* instead of 0/1; when the loop
// terminates we reclaim the temporary (it goes out of scope) and we
// we can test if the SVal is 0 or if the MemRegion is null (depending
// on what approach we take).
// For now: simulate (1) by assigning either a symbol or nil if the
// container is empty. Thus this transfer function will by default
// result in state splitting.
const Stmt *elem = S->getElement();
ProgramStateRef state = Pred->getState();
SVal elementV;
if (const DeclStmt *DS = dyn_cast<DeclStmt>(elem)) {
const VarDecl *elemD = cast<VarDecl>(DS->getSingleDecl());
assert(elemD->getInit() == 0);
elementV = state->getLValue(elemD, Pred->getLocationContext());
else {
elementV = state->getSVal(elem, Pred->getLocationContext());
ExplodedNodeSet dstLocation;
evalLocation(dstLocation, S, elem, Pred, state, elementV, NULL, false);
ExplodedNodeSet Tmp;
StmtNodeBuilder Bldr(Pred, Tmp, *currentBuilderContext);
for (ExplodedNodeSet::iterator NI = dstLocation.begin(),
NE = dstLocation.end(); NI!=NE; ++NI) {
Pred = *NI;
ProgramStateRef state = Pred->getState();
const LocationContext *LCtx = Pred->getLocationContext();
// Handle the case where the container still has elements.
SVal TrueV = svalBuilder.makeTruthVal(1);
ProgramStateRef hasElems = state->BindExpr(S, LCtx, TrueV);
// Handle the case where the container has no elements.
SVal FalseV = svalBuilder.makeTruthVal(0);
ProgramStateRef noElems = state->BindExpr(S, LCtx, FalseV);
if (loc::MemRegionVal *MV = dyn_cast<loc::MemRegionVal>(&elementV))
if (const TypedValueRegion *R =
dyn_cast<TypedValueRegion>(MV->getRegion())) {
// FIXME: The proper thing to do is to really iterate over the
// container. We will do this with dispatch logic to the store.
// For now, just 'conjure' up a symbolic value.
QualType T = R->getValueType();
unsigned Count = currentBuilderContext->getCurrentBlockCount();
SymbolRef Sym = SymMgr.getConjuredSymbol(elem, LCtx, T, Count);
SVal V = svalBuilder.makeLoc(Sym);
hasElems = hasElems->bindLoc(elementV, V);
// Bind the location to 'nil' on the false branch.
SVal nilV = svalBuilder.makeIntVal(0, T);
noElems = noElems->bindLoc(elementV, nilV);
// Create the new nodes.
Bldr.generateNode(S, Pred, hasElems);
Bldr.generateNode(S, Pred, noElems);
// Finally, run any custom checkers.
// FIXME: Eventually all pre- and post-checks should live in VisitStmt.
getCheckerManager().runCheckersForPostStmt(Dst, Tmp, S, *this);
static bool isSubclass(const ObjCInterfaceDecl *Class, IdentifierInfo *II) {
if (!Class)
return false;
if (Class->getIdentifier() == II)
return true;
return isSubclass(Class->getSuperClass(), II);
void ExprEngine::VisitObjCMessage(const ObjCMessageExpr *ME,
ExplodedNode *Pred,
ExplodedNodeSet &Dst) {
CallEventManager &CEMgr = getStateManager().getCallEventManager();
CallEventRef<ObjCMethodCall> Msg =
CEMgr.getObjCMethodCall(ME, Pred->getState(), Pred->getLocationContext());
// Handle the previsits checks.
ExplodedNodeSet dstPrevisit;
getCheckerManager().runCheckersForPreObjCMessage(dstPrevisit, Pred,
*Msg, *this);
ExplodedNodeSet dstGenericPrevisit;
getCheckerManager().runCheckersForPreCall(dstGenericPrevisit, dstPrevisit,
*Msg, *this);
// Proceed with evaluate the message expression.
ExplodedNodeSet dstEval;
StmtNodeBuilder Bldr(dstGenericPrevisit, dstEval, *currentBuilderContext);
for (ExplodedNodeSet::iterator DI = dstGenericPrevisit.begin(),
DE = dstGenericPrevisit.end(); DI != DE; ++DI) {
ExplodedNode *Pred = *DI;
ProgramStateRef State = Pred->getState();
CallEventRef<ObjCMethodCall> UpdatedMsg = Msg.cloneWithState(State);
if (UpdatedMsg->isInstanceMessage()) {
SVal recVal = UpdatedMsg->getReceiverSVal();
if (!recVal.isUndef()) {
// Bifurcate the state into nil and non-nil ones.
DefinedOrUnknownSVal receiverVal = cast<DefinedOrUnknownSVal>(recVal);
ProgramStateRef notNilState, nilState;
llvm::tie(notNilState, nilState) = State->assume(receiverVal);
// There are three cases: can be nil or non-nil, must be nil, must be
// non-nil. We ignore must be nil, and merge the rest two into non-nil.
// FIXME: This ignores many potential bugs (<rdar://problem/11733396>).
// Revisit once we have lazier constraints.
if (nilState && !notNilState) {
// Check if the "raise" message was sent.
if (Msg->getSelector() == RaiseSel) {
// If we raise an exception, for now treat it as a sink.
// Eventually we will want to handle exceptions properly.
Bldr.generateNode(currentStmt, Pred, State, true);
// Generate a transition to non-Nil state.
if (notNilState != State)
Pred = Bldr.generateNode(currentStmt, Pred, notNilState);
} else {
// Check for special class methods.
if (const ObjCInterfaceDecl *Iface = Msg->getReceiverInterface()) {
if (!NSExceptionII) {
ASTContext &Ctx = getContext();
NSExceptionII = &Ctx.Idents.get("NSException");
if (isSubclass(Iface, NSExceptionII)) {
// Lazily create a cache of the selectors.
if (!NSExceptionInstanceRaiseSelectors) {
ASTContext &Ctx = getContext();
NSExceptionInstanceRaiseSelectors =
SmallVector<IdentifierInfo*, NUM_RAISE_SELECTORS> II;
unsigned idx = 0;
// raise:format:
NSExceptionInstanceRaiseSelectors[idx++] =
Ctx.Selectors.getSelector(II.size(), &II[0]);
// raise:format:arguments:
NSExceptionInstanceRaiseSelectors[idx++] =
Ctx.Selectors.getSelector(II.size(), &II[0]);
Selector S = Msg->getSelector();
bool RaisesException = false;
for (unsigned i = 0; i < NUM_RAISE_SELECTORS; ++i) {
if (S == NSExceptionInstanceRaiseSelectors[i]) {
RaisesException = true;
if (RaisesException) {
// If we raise an exception, for now treat it as a sink.
// Eventually we will want to handle exceptions properly.
Bldr.generateNode(currentStmt, Pred, Pred->getState(), true);
// Evaluate the call.
defaultEvalCall(Bldr, Pred, *UpdatedMsg);
ExplodedNodeSet dstPostvisit;
getCheckerManager().runCheckersForPostCall(dstPostvisit, dstEval,
*Msg, *this);
// Finally, perform the post-condition check of the ObjCMessageExpr and store
// the created nodes in 'Dst'.
getCheckerManager().runCheckersForPostObjCMessage(Dst, dstPostvisit,
*Msg, *this);