1 //===- ExprEngineCXX.cpp - ExprEngine support for C++ -----------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 //  This file defines the C++ expression evaluation engine.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
15 #include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
16 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
17 #include "clang/StaticAnalyzer/Core/PathSensitive/ObjCMessage.h"
18 #include "clang/AST/DeclCXX.h"
19 
20 using namespace clang;
21 using namespace ento;
22 
23 namespace {
24 class CallExprWLItem {
25 public:
26   CallExpr::const_arg_iterator I;
27   ExplodedNode *N;
28 
29   CallExprWLItem(const CallExpr::const_arg_iterator &i, ExplodedNode *n)
30     : I(i), N(n) {}
31 };
32 }
33 
34 void ExprEngine::evalArguments(ConstExprIterator AI, ConstExprIterator AE,
35                                  const FunctionProtoType *FnType,
36                                  ExplodedNode *Pred, ExplodedNodeSet &Dst,
37                                  bool FstArgAsLValue) {
38 
39 
40   SmallVector<CallExprWLItem, 20> WorkList;
41   WorkList.reserve(AE - AI);
42   WorkList.push_back(CallExprWLItem(AI, Pred));
43 
44   while (!WorkList.empty()) {
45     CallExprWLItem Item = WorkList.back();
46     WorkList.pop_back();
47 
48     if (Item.I == AE) {
49       Dst.insert(Item.N);
50       continue;
51     }
52 
53     // Evaluate the argument.
54     ExplodedNodeSet Tmp;
55     if (FstArgAsLValue) {
56       FstArgAsLValue = false;
57     }
58 
59     Visit(*Item.I, Item.N, Tmp);
60     ++(Item.I);
61     for (ExplodedNodeSet::iterator NI=Tmp.begin(), NE=Tmp.end(); NI != NE; ++NI)
62       WorkList.push_back(CallExprWLItem(Item.I, *NI));
63   }
64 }
65 
66 void ExprEngine::evalCallee(const CallExpr *callExpr,
67                             const ExplodedNodeSet &src,
68                             ExplodedNodeSet &dest) {
69 
70   const Expr *callee = 0;
71 
72   switch (callExpr->getStmtClass()) {
73     case Stmt::CXXMemberCallExprClass: {
74       // Evaluate the implicit object argument that is the recipient of the
75       // call.
76       callee = cast<CXXMemberCallExpr>(callExpr)->getImplicitObjectArgument();
77 
78       // FIXME: handle member pointers.
79       if (!callee)
80         return;
81 
82       break;
83     }
84     default: {
85       callee = callExpr->getCallee()->IgnoreParens();
86       break;
87     }
88   }
89 
90   for (ExplodedNodeSet::iterator i = src.begin(), e = src.end(); i != e; ++i)
91     Visit(callee, *i, dest);
92 }
93 
94 const CXXThisRegion *ExprEngine::getCXXThisRegion(const CXXRecordDecl *D,
95                                                  const StackFrameContext *SFC) {
96   const Type *T = D->getTypeForDecl();
97   QualType PT = getContext().getPointerType(QualType(T, 0));
98   return svalBuilder.getRegionManager().getCXXThisRegion(PT, SFC);
99 }
100 
101 const CXXThisRegion *ExprEngine::getCXXThisRegion(const CXXMethodDecl *decl,
102                                             const StackFrameContext *frameCtx) {
103   return svalBuilder.getRegionManager().
104                     getCXXThisRegion(decl->getThisType(getContext()), frameCtx);
105 }
106 
107 void ExprEngine::CreateCXXTemporaryObject(const MaterializeTemporaryExpr *ME,
108                                           ExplodedNode *Pred,
109                                           ExplodedNodeSet &Dst) {
110   StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext);
111   const Expr *tempExpr = ME->GetTemporaryExpr()->IgnoreParens();
112   const ProgramState *state = Pred->getState();
113 
114   // Bind the temporary object to the value of the expression. Then bind
115   // the expression to the location of the object.
116   SVal V = state->getSVal(tempExpr);
117 
118   const MemRegion *R =
119     svalBuilder.getRegionManager().getCXXTempObjectRegion(ME,
120                                                  Pred->getLocationContext());
121 
122   state = state->bindLoc(loc::MemRegionVal(R), V);
123   Bldr.generateNode(ME, Pred, state->BindExpr(ME, loc::MemRegionVal(R)));
124 }
125 
126 void ExprEngine::VisitCXXConstructExpr(const CXXConstructExpr *E,
127                                        const MemRegion *Dest,
128                                        ExplodedNode *Pred,
129                                        ExplodedNodeSet &destNodes) {
130 
131   const CXXConstructorDecl *CD = E->getConstructor();
132   assert(CD);
133 
134 #if 0
135   if (!(CD->doesThisDeclarationHaveABody() && AMgr.shouldInlineCall()))
136     // FIXME: invalidate the object.
137     return;
138 #endif
139 
140   // Evaluate other arguments.
141   ExplodedNodeSet argsEvaluated;
142   const FunctionProtoType *FnType = CD->getType()->getAs<FunctionProtoType>();
143   evalArguments(E->arg_begin(), E->arg_end(), FnType, Pred, argsEvaluated);
144 
145 #if 0
146   // Is the constructor elidable?
147   if (E->isElidable()) {
148     VisitAggExpr(E->getArg(0), destNodes, Pred, Dst);
149     // FIXME: this is here to force propagation if VisitAggExpr doesn't
150     if (destNodes.empty())
151       destNodes.Add(Pred);
152     return;
153   }
154 #endif
155 
156   // Perform the previsit of the constructor.
157   ExplodedNodeSet destPreVisit;
158   getCheckerManager().runCheckersForPreStmt(destPreVisit, argsEvaluated, E,
159                                             *this);
160 
161   // Evaluate the constructor.  Currently we don't now allow checker-specific
162   // implementations of specific constructors (as we do with ordinary
163   // function calls.  We can re-evaluate this in the future.
164 
165 #if 0
166   // Inlining currently isn't fully implemented.
167 
168   if (AMgr.shouldInlineCall()) {
169     if (!Dest)
170       Dest =
171         svalBuilder.getRegionManager().getCXXTempObjectRegion(E,
172                                                   Pred->getLocationContext());
173 
174     // The callee stack frame context used to create the 'this'
175     // parameter region.
176     const StackFrameContext *SFC =
177       AMgr.getStackFrame(CD, Pred->getLocationContext(),
178                          E, currentBuilderContext->getBlock(),
179                          currentStmtIdx);
180 
181     // Create the 'this' region.
182     const CXXThisRegion *ThisR =
183       getCXXThisRegion(E->getConstructor()->getParent(), SFC);
184 
185     CallEnter Loc(E, SFC, Pred->getLocationContext());
186 
187     StmtNodeBuilder Bldr(argsEvaluated, destNodes, *currentBuilderContext);
188     for (ExplodedNodeSet::iterator NI = argsEvaluated.begin(),
189                                   NE = argsEvaluated.end(); NI != NE; ++NI) {
190       const ProgramState *state = (*NI)->getState();
191       // Setup 'this' region, so that the ctor is evaluated on the object pointed
192       // by 'Dest'.
193       state = state->bindLoc(loc::MemRegionVal(ThisR), loc::MemRegionVal(Dest));
194       Bldr.generateNode(Loc, *NI, state);
195     }
196   }
197 #endif
198 
199   // Default semantics: invalidate all regions passed as arguments.
200   ExplodedNodeSet destCall;
201   {
202     StmtNodeBuilder Bldr(destPreVisit, destCall, *currentBuilderContext);
203     for (ExplodedNodeSet::iterator
204         i = destPreVisit.begin(), e = destPreVisit.end();
205         i != e; ++i)
206     {
207       ExplodedNode *Pred = *i;
208       const LocationContext *LC = Pred->getLocationContext();
209       const ProgramState *state = Pred->getState();
210 
211       state = invalidateArguments(state, CallOrObjCMessage(E, state), LC);
212       Bldr.generateNode(E, Pred, state);
213     }
214   }
215   // Do the post visit.
216   getCheckerManager().runCheckersForPostStmt(destNodes, destCall, E, *this);
217 }
218 
219 void ExprEngine::VisitCXXDestructor(const CXXDestructorDecl *DD,
220                                       const MemRegion *Dest,
221                                       const Stmt *S,
222                                       ExplodedNode *Pred,
223                                       ExplodedNodeSet &Dst) {
224   StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext);
225   if (!(DD->doesThisDeclarationHaveABody() && AMgr.shouldInlineCall()))
226     return;
227 
228   // Create the context for 'this' region.
229   const StackFrameContext *SFC =
230     AnalysisDeclContexts.getContext(DD)->
231       getStackFrame(Pred->getLocationContext(), S,
232       currentBuilderContext->getBlock(), currentStmtIdx);
233 
234   const CXXThisRegion *ThisR = getCXXThisRegion(DD->getParent(), SFC);
235 
236   CallEnter PP(S, SFC, Pred->getLocationContext());
237 
238   const ProgramState *state = Pred->getState();
239   state = state->bindLoc(loc::MemRegionVal(ThisR), loc::MemRegionVal(Dest));
240   Bldr.generateNode(PP, Pred, state);
241 }
242 
243 void ExprEngine::VisitCXXNewExpr(const CXXNewExpr *CNE, ExplodedNode *Pred,
244                                    ExplodedNodeSet &Dst) {
245   StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext);
246 
247   unsigned blockCount = currentBuilderContext->getCurrentBlockCount();
248   DefinedOrUnknownSVal symVal =
249     svalBuilder.getConjuredSymbolVal(NULL, CNE, CNE->getType(), blockCount);
250   const MemRegion *NewReg = cast<loc::MemRegionVal>(symVal).getRegion();
251   QualType ObjTy = CNE->getType()->getAs<PointerType>()->getPointeeType();
252   const ElementRegion *EleReg =
253     getStoreManager().GetElementZeroRegion(NewReg, ObjTy);
254 
255   if (CNE->isArray()) {
256     // FIXME: allocating an array requires simulating the constructors.
257     // For now, just return a symbolicated region.
258     const ProgramState *state = Pred->getState();
259     state = state->BindExpr(CNE, loc::MemRegionVal(EleReg));
260     Bldr.generateNode(CNE, Pred, state);
261     return;
262   }
263 
264   // Evaluate constructor arguments.
265   const FunctionProtoType *FnType = NULL;
266   const CXXConstructorDecl *CD = CNE->getConstructor();
267   if (CD)
268     FnType = CD->getType()->getAs<FunctionProtoType>();
269   ExplodedNodeSet argsEvaluated;
270   Bldr.takeNodes(Pred);
271   evalArguments(CNE->constructor_arg_begin(), CNE->constructor_arg_end(),
272                 FnType, Pred, argsEvaluated);
273   Bldr.addNodes(argsEvaluated);
274 
275   // Initialize the object region and bind the 'new' expression.
276   for (ExplodedNodeSet::iterator I = argsEvaluated.begin(),
277                                  E = argsEvaluated.end(); I != E; ++I) {
278 
279     const ProgramState *state = (*I)->getState();
280 
281     // Accumulate list of regions that are invalidated.
282     // FIXME: Eventually we should unify the logic for constructor
283     // processing in one place.
284     SmallVector<const MemRegion*, 10> regionsToInvalidate;
285     for (CXXNewExpr::const_arg_iterator
286           ai = CNE->constructor_arg_begin(), ae = CNE->constructor_arg_end();
287           ai != ae; ++ai)
288     {
289       SVal val = state->getSVal(*ai);
290       if (const MemRegion *region = val.getAsRegion())
291         regionsToInvalidate.push_back(region);
292     }
293 
294     if (ObjTy->isRecordType()) {
295       regionsToInvalidate.push_back(EleReg);
296       // Invalidate the regions.
297       state = state->invalidateRegions(regionsToInvalidate,
298                                        CNE, blockCount, 0,
299                                        /* invalidateGlobals = */ true);
300 
301     } else {
302       // Invalidate the regions.
303       state = state->invalidateRegions(regionsToInvalidate,
304                                        CNE, blockCount, 0,
305                                        /* invalidateGlobals = */ true);
306 
307       if (CNE->hasInitializer()) {
308         SVal V = state->getSVal(*CNE->constructor_arg_begin());
309         state = state->bindLoc(loc::MemRegionVal(EleReg), V);
310       } else {
311         // Explicitly set to undefined, because currently we retrieve symbolic
312         // value from symbolic region.
313         state = state->bindLoc(loc::MemRegionVal(EleReg), UndefinedVal());
314       }
315     }
316     state = state->BindExpr(CNE, loc::MemRegionVal(EleReg));
317     Bldr.generateNode(CNE, *I, state);
318   }
319 }
320 
321 void ExprEngine::VisitCXXDeleteExpr(const CXXDeleteExpr *CDE,
322                                     ExplodedNode *Pred, ExplodedNodeSet &Dst) {
323   // Should do more checking.
324   ExplodedNodeSet Argevaluated;
325   Visit(CDE->getArgument(), Pred, Argevaluated);
326   StmtNodeBuilder Bldr(Argevaluated, Dst, *currentBuilderContext);
327   for (ExplodedNodeSet::iterator I = Argevaluated.begin(),
328                                  E = Argevaluated.end(); I != E; ++I) {
329     const ProgramState *state = (*I)->getState();
330     Bldr.generateNode(CDE, *I, state);
331   }
332 }
333 
334 void ExprEngine::VisitCXXThisExpr(const CXXThisExpr *TE, ExplodedNode *Pred,
335                                     ExplodedNodeSet &Dst) {
336   StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext);
337 
338   // Get the this object region from StoreManager.
339   const MemRegion *R =
340     svalBuilder.getRegionManager().getCXXThisRegion(
341                                   getContext().getCanonicalType(TE->getType()),
342                                                Pred->getLocationContext());
343 
344   const ProgramState *state = Pred->getState();
345   SVal V = state->getSVal(loc::MemRegionVal(R));
346   Bldr.generateNode(TE, Pred, state->BindExpr(TE, V));
347 }
348