forked from OSchip/llvm-project
270 lines
10 KiB
C++
270 lines
10 KiB
C++
//=-- ExprEngineObjC.cpp - ExprEngine support for Objective-C ---*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines ExprEngine's support for Objective-C expressions.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/StaticAnalyzer/Core/CheckerManager.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/ObjCMessage.h"
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using namespace clang;
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using namespace ento;
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void ExprEngine::VisitLvalObjCIvarRefExpr(const ObjCIvarRefExpr *Ex,
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ExplodedNode *Pred,
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ExplodedNodeSet &Dst) {
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const ProgramState *state = Pred->getState();
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SVal baseVal = state->getSVal(Ex->getBase());
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SVal location = state->getLValue(Ex->getDecl(), baseVal);
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ExplodedNodeSet dstIvar;
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StmtNodeBuilder Bldr(Pred, dstIvar, *currentBuilderContext);
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Bldr.generateNode(Ex, Pred, state->BindExpr(Ex, location));
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// Perform the post-condition check of the ObjCIvarRefExpr and store
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// the created nodes in 'Dst'.
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getCheckerManager().runCheckersForPostStmt(Dst, dstIvar, Ex, *this);
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}
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void ExprEngine::VisitObjCAtSynchronizedStmt(const ObjCAtSynchronizedStmt *S,
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ExplodedNode *Pred,
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ExplodedNodeSet &Dst) {
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getCheckerManager().runCheckersForPreStmt(Dst, Pred, S, *this);
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}
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void ExprEngine::VisitObjCForCollectionStmt(const ObjCForCollectionStmt *S,
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ExplodedNode *Pred,
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ExplodedNodeSet &Dst) {
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// ObjCForCollectionStmts are processed in two places. This method
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// handles the case where an ObjCForCollectionStmt* occurs as one of the
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// statements within a basic block. This transfer function does two things:
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//
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// (1) binds the next container value to 'element'. This creates a new
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// node in the ExplodedGraph.
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//
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// (2) binds the value 0/1 to the ObjCForCollectionStmt* itself, indicating
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// whether or not the container has any more elements. This value
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// will be tested in ProcessBranch. We need to explicitly bind
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// this value because a container can contain nil elements.
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//
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// FIXME: Eventually this logic should actually do dispatches to
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// 'countByEnumeratingWithState:objects:count:' (NSFastEnumeration).
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// This will require simulating a temporary NSFastEnumerationState, either
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// through an SVal or through the use of MemRegions. This value can
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// be affixed to the ObjCForCollectionStmt* instead of 0/1; when the loop
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// terminates we reclaim the temporary (it goes out of scope) and we
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// we can test if the SVal is 0 or if the MemRegion is null (depending
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// on what approach we take).
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//
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// For now: simulate (1) by assigning either a symbol or nil if the
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// container is empty. Thus this transfer function will by default
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// result in state splitting.
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const Stmt *elem = S->getElement();
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const ProgramState *state = Pred->getState();
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SVal elementV;
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StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext);
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if (const DeclStmt *DS = dyn_cast<DeclStmt>(elem)) {
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const VarDecl *elemD = cast<VarDecl>(DS->getSingleDecl());
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assert(elemD->getInit() == 0);
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elementV = state->getLValue(elemD, Pred->getLocationContext());
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}
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else {
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elementV = state->getSVal(elem);
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}
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ExplodedNodeSet dstLocation;
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Bldr.takeNodes(Pred);
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evalLocation(dstLocation, elem, Pred, state, elementV, NULL, false);
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Bldr.addNodes(dstLocation);
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for (ExplodedNodeSet::iterator NI = dstLocation.begin(),
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NE = dstLocation.end(); NI!=NE; ++NI) {
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Pred = *NI;
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const ProgramState *state = Pred->getState();
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// Handle the case where the container still has elements.
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SVal TrueV = svalBuilder.makeTruthVal(1);
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const ProgramState *hasElems = state->BindExpr(S, TrueV);
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// Handle the case where the container has no elements.
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SVal FalseV = svalBuilder.makeTruthVal(0);
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const ProgramState *noElems = state->BindExpr(S, FalseV);
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if (loc::MemRegionVal *MV = dyn_cast<loc::MemRegionVal>(&elementV))
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if (const TypedValueRegion *R =
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dyn_cast<TypedValueRegion>(MV->getRegion())) {
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// FIXME: The proper thing to do is to really iterate over the
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// container. We will do this with dispatch logic to the store.
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// For now, just 'conjure' up a symbolic value.
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QualType T = R->getValueType();
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assert(Loc::isLocType(T));
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unsigned Count = currentBuilderContext->getCurrentBlockCount();
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SymbolRef Sym = SymMgr.getConjuredSymbol(elem, T, Count);
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SVal V = svalBuilder.makeLoc(Sym);
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hasElems = hasElems->bindLoc(elementV, V);
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// Bind the location to 'nil' on the false branch.
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SVal nilV = svalBuilder.makeIntVal(0, T);
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noElems = noElems->bindLoc(elementV, nilV);
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}
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// Create the new nodes.
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Bldr.generateNode(S, Pred, hasElems);
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Bldr.generateNode(S, Pred, noElems);
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}
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}
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void ExprEngine::VisitObjCMessage(const ObjCMessage &msg,
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ExplodedNode *Pred,
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ExplodedNodeSet &Dst) {
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// Handle the previsits checks.
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ExplodedNodeSet dstPrevisit;
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getCheckerManager().runCheckersForPreObjCMessage(dstPrevisit, Pred,
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msg, *this);
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// Proceed with evaluate the message expression.
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ExplodedNodeSet dstEval;
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StmtNodeBuilder Bldr(dstPrevisit, dstEval, *currentBuilderContext);
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for (ExplodedNodeSet::iterator DI = dstPrevisit.begin(),
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DE = dstPrevisit.end(); DI != DE; ++DI) {
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ExplodedNode *Pred = *DI;
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bool RaisesException = false;
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if (const Expr *Receiver = msg.getInstanceReceiver()) {
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const ProgramState *state = Pred->getState();
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SVal recVal = state->getSVal(Receiver);
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if (!recVal.isUndef()) {
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// Bifurcate the state into nil and non-nil ones.
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DefinedOrUnknownSVal receiverVal = cast<DefinedOrUnknownSVal>(recVal);
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const ProgramState *notNilState, *nilState;
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llvm::tie(notNilState, nilState) = state->assume(receiverVal);
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// There are three cases: can be nil or non-nil, must be nil, must be
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// non-nil. We ignore must be nil, and merge the rest two into non-nil.
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if (nilState && !notNilState) {
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continue;
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}
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// Check if the "raise" message was sent.
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assert(notNilState);
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if (msg.getSelector() == RaiseSel)
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RaisesException = true;
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// If we raise an exception, for now treat it as a sink.
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// Eventually we will want to handle exceptions properly.
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// Dispatch to plug-in transfer function.
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evalObjCMessage(Bldr, msg, Pred, notNilState, RaisesException);
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}
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}
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else if (const ObjCInterfaceDecl *Iface = msg.getReceiverInterface()) {
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IdentifierInfo* ClsName = Iface->getIdentifier();
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Selector S = msg.getSelector();
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// Check for special instance methods.
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if (!NSExceptionII) {
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ASTContext &Ctx = getContext();
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NSExceptionII = &Ctx.Idents.get("NSException");
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}
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if (ClsName == NSExceptionII) {
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enum { NUM_RAISE_SELECTORS = 2 };
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// Lazily create a cache of the selectors.
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if (!NSExceptionInstanceRaiseSelectors) {
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ASTContext &Ctx = getContext();
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NSExceptionInstanceRaiseSelectors =
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new Selector[NUM_RAISE_SELECTORS];
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SmallVector<IdentifierInfo*, NUM_RAISE_SELECTORS> II;
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unsigned idx = 0;
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// raise:format:
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II.push_back(&Ctx.Idents.get("raise"));
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II.push_back(&Ctx.Idents.get("format"));
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NSExceptionInstanceRaiseSelectors[idx++] =
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Ctx.Selectors.getSelector(II.size(), &II[0]);
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// raise:format::arguments:
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II.push_back(&Ctx.Idents.get("arguments"));
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NSExceptionInstanceRaiseSelectors[idx++] =
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Ctx.Selectors.getSelector(II.size(), &II[0]);
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}
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for (unsigned i = 0; i < NUM_RAISE_SELECTORS; ++i)
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if (S == NSExceptionInstanceRaiseSelectors[i]) {
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RaisesException = true;
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break;
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}
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}
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// If we raise an exception, for now treat it as a sink.
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// Eventually we will want to handle exceptions properly.
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// Dispatch to plug-in transfer function.
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evalObjCMessage(Bldr, msg, Pred, Pred->getState(), RaisesException);
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}
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}
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// Finally, perform the post-condition check of the ObjCMessageExpr and store
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// the created nodes in 'Dst'.
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getCheckerManager().runCheckersForPostObjCMessage(Dst, dstEval, msg, *this);
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}
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void ExprEngine::evalObjCMessage(StmtNodeBuilder &Bldr,
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const ObjCMessage &msg,
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ExplodedNode *Pred,
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const ProgramState *state,
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bool GenSink) {
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// First handle the return value.
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SVal ReturnValue = UnknownVal();
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// Some method families have known return values.
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switch (msg.getMethodFamily()) {
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default:
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break;
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case OMF_autorelease:
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case OMF_retain:
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case OMF_self: {
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// These methods return their receivers.
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const Expr *ReceiverE = msg.getInstanceReceiver();
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if (ReceiverE)
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ReturnValue = state->getSVal(ReceiverE);
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break;
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}
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}
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// If we failed to figure out the return value, use a conjured value instead.
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if (ReturnValue.isUnknown()) {
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SValBuilder &SVB = getSValBuilder();
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QualType ResultTy = msg.getResultType(getContext());
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unsigned Count = currentBuilderContext->getCurrentBlockCount();
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const Expr *CurrentE = cast<Expr>(currentStmt);
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ReturnValue = SVB.getConjuredSymbolVal(NULL, CurrentE, ResultTy, Count);
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}
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// Bind the return value.
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state = state->BindExpr(currentStmt, ReturnValue);
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// Invalidate the arguments (and the receiver)
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const LocationContext *LC = Pred->getLocationContext();
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state = invalidateArguments(state, CallOrObjCMessage(msg, state), LC);
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// And create the new node.
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Bldr.generateNode(msg.getOriginExpr(), Pred, state, GenSink);
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assert(Bldr.hasGeneratedNodes());
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}
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