ExprEngineObjC.cpp revision 234353
1226586Sdim//=-- ExprEngineObjC.cpp - ExprEngine support for Objective-C ---*- C++ -*-===// 2226586Sdim// 3226586Sdim// The LLVM Compiler Infrastructure 4226586Sdim// 5226586Sdim// This file is distributed under the University of Illinois Open Source 6226586Sdim// License. See LICENSE.TXT for details. 7226586Sdim// 8226586Sdim//===----------------------------------------------------------------------===// 9226586Sdim// 10226586Sdim// This file defines ExprEngine's support for Objective-C expressions. 11226586Sdim// 12226586Sdim//===----------------------------------------------------------------------===// 13226586Sdim 14234353Sdim#include "clang/AST/StmtObjC.h" 15226586Sdim#include "clang/StaticAnalyzer/Core/CheckerManager.h" 16226586Sdim#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h" 17226586Sdim#include "clang/StaticAnalyzer/Core/PathSensitive/ObjCMessage.h" 18226586Sdim 19226586Sdimusing namespace clang; 20226586Sdimusing namespace ento; 21226586Sdim 22226586Sdimvoid ExprEngine::VisitLvalObjCIvarRefExpr(const ObjCIvarRefExpr *Ex, 23226586Sdim ExplodedNode *Pred, 24226586Sdim ExplodedNodeSet &Dst) { 25234353Sdim ProgramStateRef state = Pred->getState(); 26234353Sdim const LocationContext *LCtx = Pred->getLocationContext(); 27234353Sdim SVal baseVal = state->getSVal(Ex->getBase(), LCtx); 28226586Sdim SVal location = state->getLValue(Ex->getDecl(), baseVal); 29226586Sdim 30226586Sdim ExplodedNodeSet dstIvar; 31234353Sdim StmtNodeBuilder Bldr(Pred, dstIvar, *currentBuilderContext); 32234353Sdim Bldr.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, location)); 33226586Sdim 34226586Sdim // Perform the post-condition check of the ObjCIvarRefExpr and store 35226586Sdim // the created nodes in 'Dst'. 36226586Sdim getCheckerManager().runCheckersForPostStmt(Dst, dstIvar, Ex, *this); 37226586Sdim} 38226586Sdim 39226586Sdimvoid ExprEngine::VisitObjCAtSynchronizedStmt(const ObjCAtSynchronizedStmt *S, 40226586Sdim ExplodedNode *Pred, 41226586Sdim ExplodedNodeSet &Dst) { 42226586Sdim getCheckerManager().runCheckersForPreStmt(Dst, Pred, S, *this); 43226586Sdim} 44226586Sdim 45226586Sdimvoid ExprEngine::VisitObjCForCollectionStmt(const ObjCForCollectionStmt *S, 46226586Sdim ExplodedNode *Pred, 47226586Sdim ExplodedNodeSet &Dst) { 48226586Sdim 49226586Sdim // ObjCForCollectionStmts are processed in two places. This method 50226586Sdim // handles the case where an ObjCForCollectionStmt* occurs as one of the 51226586Sdim // statements within a basic block. This transfer function does two things: 52226586Sdim // 53226586Sdim // (1) binds the next container value to 'element'. This creates a new 54226586Sdim // node in the ExplodedGraph. 55226586Sdim // 56226586Sdim // (2) binds the value 0/1 to the ObjCForCollectionStmt* itself, indicating 57226586Sdim // whether or not the container has any more elements. This value 58226586Sdim // will be tested in ProcessBranch. We need to explicitly bind 59226586Sdim // this value because a container can contain nil elements. 60226586Sdim // 61226586Sdim // FIXME: Eventually this logic should actually do dispatches to 62226586Sdim // 'countByEnumeratingWithState:objects:count:' (NSFastEnumeration). 63226586Sdim // This will require simulating a temporary NSFastEnumerationState, either 64226586Sdim // through an SVal or through the use of MemRegions. This value can 65226586Sdim // be affixed to the ObjCForCollectionStmt* instead of 0/1; when the loop 66226586Sdim // terminates we reclaim the temporary (it goes out of scope) and we 67226586Sdim // we can test if the SVal is 0 or if the MemRegion is null (depending 68226586Sdim // on what approach we take). 69226586Sdim // 70226586Sdim // For now: simulate (1) by assigning either a symbol or nil if the 71226586Sdim // container is empty. Thus this transfer function will by default 72226586Sdim // result in state splitting. 73234353Sdim 74226586Sdim const Stmt *elem = S->getElement(); 75234353Sdim ProgramStateRef state = Pred->getState(); 76226586Sdim SVal elementV; 77234353Sdim StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext); 78226586Sdim 79226586Sdim if (const DeclStmt *DS = dyn_cast<DeclStmt>(elem)) { 80226586Sdim const VarDecl *elemD = cast<VarDecl>(DS->getSingleDecl()); 81226586Sdim assert(elemD->getInit() == 0); 82226586Sdim elementV = state->getLValue(elemD, Pred->getLocationContext()); 83226586Sdim } 84226586Sdim else { 85234353Sdim elementV = state->getSVal(elem, Pred->getLocationContext()); 86226586Sdim } 87226586Sdim 88226586Sdim ExplodedNodeSet dstLocation; 89234353Sdim Bldr.takeNodes(Pred); 90234353Sdim evalLocation(dstLocation, S, elem, Pred, state, elementV, NULL, false); 91234353Sdim Bldr.addNodes(dstLocation); 92226586Sdim 93226586Sdim for (ExplodedNodeSet::iterator NI = dstLocation.begin(), 94226586Sdim NE = dstLocation.end(); NI!=NE; ++NI) { 95226586Sdim Pred = *NI; 96234353Sdim ProgramStateRef state = Pred->getState(); 97234353Sdim const LocationContext *LCtx = Pred->getLocationContext(); 98226586Sdim 99226586Sdim // Handle the case where the container still has elements. 100226586Sdim SVal TrueV = svalBuilder.makeTruthVal(1); 101234353Sdim ProgramStateRef hasElems = state->BindExpr(S, LCtx, TrueV); 102226586Sdim 103226586Sdim // Handle the case where the container has no elements. 104226586Sdim SVal FalseV = svalBuilder.makeTruthVal(0); 105234353Sdim ProgramStateRef noElems = state->BindExpr(S, LCtx, FalseV); 106226586Sdim 107226586Sdim if (loc::MemRegionVal *MV = dyn_cast<loc::MemRegionVal>(&elementV)) 108226586Sdim if (const TypedValueRegion *R = 109226586Sdim dyn_cast<TypedValueRegion>(MV->getRegion())) { 110226586Sdim // FIXME: The proper thing to do is to really iterate over the 111226586Sdim // container. We will do this with dispatch logic to the store. 112226586Sdim // For now, just 'conjure' up a symbolic value. 113226586Sdim QualType T = R->getValueType(); 114226586Sdim assert(Loc::isLocType(T)); 115234353Sdim unsigned Count = currentBuilderContext->getCurrentBlockCount(); 116234353Sdim SymbolRef Sym = SymMgr.getConjuredSymbol(elem, LCtx, T, Count); 117226586Sdim SVal V = svalBuilder.makeLoc(Sym); 118226586Sdim hasElems = hasElems->bindLoc(elementV, V); 119226586Sdim 120226586Sdim // Bind the location to 'nil' on the false branch. 121226586Sdim SVal nilV = svalBuilder.makeIntVal(0, T); 122226586Sdim noElems = noElems->bindLoc(elementV, nilV); 123226586Sdim } 124226586Sdim 125226586Sdim // Create the new nodes. 126234353Sdim Bldr.generateNode(S, Pred, hasElems); 127234353Sdim Bldr.generateNode(S, Pred, noElems); 128226586Sdim } 129226586Sdim} 130226586Sdim 131226586Sdimvoid ExprEngine::VisitObjCMessage(const ObjCMessage &msg, 132226586Sdim ExplodedNode *Pred, 133226586Sdim ExplodedNodeSet &Dst) { 134226586Sdim 135226586Sdim // Handle the previsits checks. 136226586Sdim ExplodedNodeSet dstPrevisit; 137226586Sdim getCheckerManager().runCheckersForPreObjCMessage(dstPrevisit, Pred, 138226586Sdim msg, *this); 139226586Sdim 140226586Sdim // Proceed with evaluate the message expression. 141226586Sdim ExplodedNodeSet dstEval; 142234353Sdim StmtNodeBuilder Bldr(dstPrevisit, dstEval, *currentBuilderContext); 143234353Sdim 144226586Sdim for (ExplodedNodeSet::iterator DI = dstPrevisit.begin(), 145226586Sdim DE = dstPrevisit.end(); DI != DE; ++DI) { 146226586Sdim 147226586Sdim ExplodedNode *Pred = *DI; 148226586Sdim bool RaisesException = false; 149226586Sdim 150226586Sdim if (const Expr *Receiver = msg.getInstanceReceiver()) { 151234353Sdim ProgramStateRef state = Pred->getState(); 152234353Sdim SVal recVal = state->getSVal(Receiver, Pred->getLocationContext()); 153226586Sdim if (!recVal.isUndef()) { 154226586Sdim // Bifurcate the state into nil and non-nil ones. 155226586Sdim DefinedOrUnknownSVal receiverVal = cast<DefinedOrUnknownSVal>(recVal); 156226586Sdim 157234353Sdim ProgramStateRef notNilState, nilState; 158226586Sdim llvm::tie(notNilState, nilState) = state->assume(receiverVal); 159226586Sdim 160226586Sdim // There are three cases: can be nil or non-nil, must be nil, must be 161226586Sdim // non-nil. We ignore must be nil, and merge the rest two into non-nil. 162226586Sdim if (nilState && !notNilState) { 163226586Sdim continue; 164226586Sdim } 165226586Sdim 166226586Sdim // Check if the "raise" message was sent. 167226586Sdim assert(notNilState); 168226586Sdim if (msg.getSelector() == RaiseSel) 169226586Sdim RaisesException = true; 170226586Sdim 171234353Sdim // If we raise an exception, for now treat it as a sink. 172226586Sdim // Eventually we will want to handle exceptions properly. 173226586Sdim // Dispatch to plug-in transfer function. 174234353Sdim evalObjCMessage(Bldr, msg, Pred, notNilState, RaisesException); 175226586Sdim } 176226586Sdim } 177226586Sdim else if (const ObjCInterfaceDecl *Iface = msg.getReceiverInterface()) { 178226586Sdim IdentifierInfo* ClsName = Iface->getIdentifier(); 179226586Sdim Selector S = msg.getSelector(); 180226586Sdim 181226586Sdim // Check for special instance methods. 182226586Sdim if (!NSExceptionII) { 183226586Sdim ASTContext &Ctx = getContext(); 184226586Sdim NSExceptionII = &Ctx.Idents.get("NSException"); 185226586Sdim } 186226586Sdim 187226586Sdim if (ClsName == NSExceptionII) { 188226586Sdim enum { NUM_RAISE_SELECTORS = 2 }; 189226586Sdim 190226586Sdim // Lazily create a cache of the selectors. 191226586Sdim if (!NSExceptionInstanceRaiseSelectors) { 192226586Sdim ASTContext &Ctx = getContext(); 193226586Sdim NSExceptionInstanceRaiseSelectors = 194226586Sdim new Selector[NUM_RAISE_SELECTORS]; 195226586Sdim SmallVector<IdentifierInfo*, NUM_RAISE_SELECTORS> II; 196226586Sdim unsigned idx = 0; 197226586Sdim 198226586Sdim // raise:format: 199226586Sdim II.push_back(&Ctx.Idents.get("raise")); 200226586Sdim II.push_back(&Ctx.Idents.get("format")); 201226586Sdim NSExceptionInstanceRaiseSelectors[idx++] = 202226586Sdim Ctx.Selectors.getSelector(II.size(), &II[0]); 203226586Sdim 204226586Sdim // raise:format::arguments: 205226586Sdim II.push_back(&Ctx.Idents.get("arguments")); 206226586Sdim NSExceptionInstanceRaiseSelectors[idx++] = 207226586Sdim Ctx.Selectors.getSelector(II.size(), &II[0]); 208226586Sdim } 209226586Sdim 210226586Sdim for (unsigned i = 0; i < NUM_RAISE_SELECTORS; ++i) 211226586Sdim if (S == NSExceptionInstanceRaiseSelectors[i]) { 212226586Sdim RaisesException = true; 213226586Sdim break; 214226586Sdim } 215226586Sdim } 216226586Sdim 217234353Sdim // If we raise an exception, for now treat it as a sink. 218226586Sdim // Eventually we will want to handle exceptions properly. 219226586Sdim // Dispatch to plug-in transfer function. 220234353Sdim evalObjCMessage(Bldr, msg, Pred, Pred->getState(), RaisesException); 221226586Sdim } 222226586Sdim } 223226586Sdim 224226586Sdim // Finally, perform the post-condition check of the ObjCMessageExpr and store 225226586Sdim // the created nodes in 'Dst'. 226226586Sdim getCheckerManager().runCheckersForPostObjCMessage(Dst, dstEval, msg, *this); 227226586Sdim} 228226586Sdim 229234353Sdimvoid ExprEngine::evalObjCMessage(StmtNodeBuilder &Bldr, 230234353Sdim const ObjCMessage &msg, 231226586Sdim ExplodedNode *Pred, 232234353Sdim ProgramStateRef state, 233234353Sdim bool GenSink) { 234226586Sdim // First handle the return value. 235226586Sdim SVal ReturnValue = UnknownVal(); 236226586Sdim 237226586Sdim // Some method families have known return values. 238226586Sdim switch (msg.getMethodFamily()) { 239226586Sdim default: 240226586Sdim break; 241226586Sdim case OMF_autorelease: 242226586Sdim case OMF_retain: 243226586Sdim case OMF_self: { 244226586Sdim // These methods return their receivers. 245226586Sdim const Expr *ReceiverE = msg.getInstanceReceiver(); 246226586Sdim if (ReceiverE) 247234353Sdim ReturnValue = state->getSVal(ReceiverE, Pred->getLocationContext()); 248226586Sdim break; 249226586Sdim } 250226586Sdim } 251226586Sdim 252226586Sdim // If we failed to figure out the return value, use a conjured value instead. 253226586Sdim if (ReturnValue.isUnknown()) { 254226586Sdim SValBuilder &SVB = getSValBuilder(); 255226586Sdim QualType ResultTy = msg.getResultType(getContext()); 256234353Sdim unsigned Count = currentBuilderContext->getCurrentBlockCount(); 257226586Sdim const Expr *CurrentE = cast<Expr>(currentStmt); 258234353Sdim const LocationContext *LCtx = Pred->getLocationContext(); 259234353Sdim ReturnValue = SVB.getConjuredSymbolVal(NULL, CurrentE, LCtx, ResultTy, Count); 260226586Sdim } 261226586Sdim 262226586Sdim // Bind the return value. 263234353Sdim const LocationContext *LCtx = Pred->getLocationContext(); 264234353Sdim state = state->BindExpr(currentStmt, LCtx, ReturnValue); 265226586Sdim 266226586Sdim // Invalidate the arguments (and the receiver) 267234353Sdim state = invalidateArguments(state, CallOrObjCMessage(msg, state, LCtx), LCtx); 268226586Sdim 269226586Sdim // And create the new node. 270234353Sdim Bldr.generateNode(msg.getMessageExpr(), Pred, state, GenSink); 271234353Sdim assert(Bldr.hasGeneratedNodes()); 272226586Sdim} 273226586Sdim 274