1 //=-- ExprEngineC.cpp - ExprEngine support for C expressions ----*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines ExprEngine's support for C expressions.
12 //===----------------------------------------------------------------------===//
14 #include "clang/AST/ExprCXX.h"
15 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
16 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
18 using namespace clang;
22 void ExprEngine::VisitBinaryOperator(const BinaryOperator* B,
24 ExplodedNodeSet &Dst) {
26 Expr *LHS = B->getLHS()->IgnoreParens();
27 Expr *RHS = B->getRHS()->IgnoreParens();
29 // FIXME: Prechecks eventually go in ::Visit().
30 ExplodedNodeSet CheckedSet;
32 getCheckerManager().runCheckersForPreStmt(CheckedSet, Pred, B, *this);
34 // With both the LHS and RHS evaluated, process the operation itself.
35 for (ExplodedNodeSet::iterator it=CheckedSet.begin(), ei=CheckedSet.end();
38 ProgramStateRef state = (*it)->getState();
39 const LocationContext *LCtx = (*it)->getLocationContext();
40 SVal LeftV = state->getSVal(LHS, LCtx);
41 SVal RightV = state->getSVal(RHS, LCtx);
43 BinaryOperator::Opcode Op = B->getOpcode();
45 if (Op == BO_Assign) {
46 // EXPERIMENTAL: "Conjured" symbols.
47 // FIXME: Handle structs.
48 if (RightV.isUnknown()) {
49 unsigned Count = currBldrCtx->blockCount();
50 RightV = svalBuilder.conjureSymbolVal(nullptr, B->getRHS(), LCtx,
53 // Simulate the effects of a "store": bind the value of the RHS
54 // to the L-Value represented by the LHS.
55 SVal ExprVal = B->isGLValue() ? LeftV : RightV;
56 evalStore(Tmp2, B, LHS, *it, state->BindExpr(B, LCtx, ExprVal),
61 if (!B->isAssignmentOp()) {
62 StmtNodeBuilder Bldr(*it, Tmp2, *currBldrCtx);
64 if (B->isAdditiveOp()) {
65 // If one of the operands is a location, conjure a symbol for the other
66 // one (offset) if it's unknown so that memory arithmetic always
67 // results in an ElementRegion.
68 // TODO: This can be removed after we enable history tracking with
70 unsigned Count = currBldrCtx->blockCount();
71 if (LeftV.getAs<Loc>() &&
72 RHS->getType()->isIntegralOrEnumerationType() &&
74 RightV = svalBuilder.conjureSymbolVal(RHS, LCtx, RHS->getType(),
77 if (RightV.getAs<Loc>() &&
78 LHS->getType()->isIntegralOrEnumerationType() &&
80 LeftV = svalBuilder.conjureSymbolVal(LHS, LCtx, LHS->getType(),
85 // Although we don't yet model pointers-to-members, we do need to make
86 // sure that the members of temporaries have a valid 'this' pointer for
88 if (B->getOpcode() == BO_PtrMemD)
89 state = createTemporaryRegionIfNeeded(state, LCtx, LHS);
91 // Process non-assignments except commas or short-circuited
92 // logical expressions (LAnd and LOr).
93 SVal Result = evalBinOp(state, Op, LeftV, RightV, B->getType());
94 if (Result.isUnknown()) {
95 Bldr.generateNode(B, *it, state);
99 state = state->BindExpr(B, LCtx, Result);
100 Bldr.generateNode(B, *it, state);
104 assert (B->isCompoundAssignmentOp());
108 llvm_unreachable("Invalid opcode for compound assignment.");
109 case BO_MulAssign: Op = BO_Mul; break;
110 case BO_DivAssign: Op = BO_Div; break;
111 case BO_RemAssign: Op = BO_Rem; break;
112 case BO_AddAssign: Op = BO_Add; break;
113 case BO_SubAssign: Op = BO_Sub; break;
114 case BO_ShlAssign: Op = BO_Shl; break;
115 case BO_ShrAssign: Op = BO_Shr; break;
116 case BO_AndAssign: Op = BO_And; break;
117 case BO_XorAssign: Op = BO_Xor; break;
118 case BO_OrAssign: Op = BO_Or; break;
121 // Perform a load (the LHS). This performs the checks for
122 // null dereferences, and so on.
124 SVal location = LeftV;
125 evalLoad(Tmp, B, LHS, *it, state, location);
127 for (ExplodedNodeSet::iterator I = Tmp.begin(), E = Tmp.end(); I != E;
130 state = (*I)->getState();
131 const LocationContext *LCtx = (*I)->getLocationContext();
132 SVal V = state->getSVal(LHS, LCtx);
134 // Get the computation type.
136 cast<CompoundAssignOperator>(B)->getComputationResultType();
137 CTy = getContext().getCanonicalType(CTy);
140 cast<CompoundAssignOperator>(B)->getComputationLHSType();
141 CLHSTy = getContext().getCanonicalType(CLHSTy);
143 QualType LTy = getContext().getCanonicalType(LHS->getType());
146 V = svalBuilder.evalCast(V, CLHSTy, LTy);
148 // Compute the result of the operation.
149 SVal Result = svalBuilder.evalCast(evalBinOp(state, Op, V, RightV, CTy),
152 // EXPERIMENTAL: "Conjured" symbols.
153 // FIXME: Handle structs.
157 if (Result.isUnknown()) {
158 // The symbolic value is actually for the type of the left-hand side
159 // expression, not the computation type, as this is the value the
160 // LValue on the LHS will bind to.
161 LHSVal = svalBuilder.conjureSymbolVal(nullptr, B->getRHS(), LCtx, LTy,
162 currBldrCtx->blockCount());
163 // However, we need to convert the symbol to the computation type.
164 Result = svalBuilder.evalCast(LHSVal, CTy, LTy);
167 // The left-hand side may bind to a different value then the
169 LHSVal = svalBuilder.evalCast(Result, LTy, CTy);
172 // In C++, assignment and compound assignment operators return an
175 state = state->BindExpr(B, LCtx, location);
177 state = state->BindExpr(B, LCtx, Result);
179 evalStore(Tmp2, B, LHS, *I, state, location, LHSVal);
183 // FIXME: postvisits eventually go in ::Visit()
184 getCheckerManager().runCheckersForPostStmt(Dst, Tmp2, B, *this);
187 void ExprEngine::VisitBlockExpr(const BlockExpr *BE, ExplodedNode *Pred,
188 ExplodedNodeSet &Dst) {
190 CanQualType T = getContext().getCanonicalType(BE->getType());
192 const BlockDecl *BD = BE->getBlockDecl();
193 // Get the value of the block itself.
194 SVal V = svalBuilder.getBlockPointer(BD, T,
195 Pred->getLocationContext(),
196 currBldrCtx->blockCount());
198 ProgramStateRef State = Pred->getState();
200 // If we created a new MemRegion for the block, we should explicitly bind
201 // the captured variables.
202 if (const BlockDataRegion *BDR =
203 dyn_cast_or_null<BlockDataRegion>(V.getAsRegion())) {
205 BlockDataRegion::referenced_vars_iterator I = BDR->referenced_vars_begin(),
206 E = BDR->referenced_vars_end();
208 auto CI = BD->capture_begin();
209 auto CE = BD->capture_end();
210 for (; I != E; ++I) {
211 const VarRegion *capturedR = I.getCapturedRegion();
212 const VarRegion *originalR = I.getOriginalRegion();
214 // If the capture had a copy expression, use the result of evaluating
215 // that expression, otherwise use the original value.
216 // We rely on the invariant that the block declaration's capture variables
217 // are a prefix of the BlockDataRegion's referenced vars (which may include
218 // referenced globals, etc.) to enable fast lookup of the capture for a
219 // given referenced var.
220 const Expr *copyExpr = nullptr;
222 assert(CI->getVariable() == capturedR->getDecl());
223 copyExpr = CI->getCopyExpr();
227 if (capturedR != originalR) {
230 originalV = State->getSVal(copyExpr, Pred->getLocationContext());
232 originalV = State->getSVal(loc::MemRegionVal(originalR));
234 State = State->bindLoc(loc::MemRegionVal(capturedR), originalV);
240 StmtNodeBuilder Bldr(Pred, Tmp, *currBldrCtx);
241 Bldr.generateNode(BE, Pred,
242 State->BindExpr(BE, Pred->getLocationContext(), V),
243 nullptr, ProgramPoint::PostLValueKind);
245 // FIXME: Move all post/pre visits to ::Visit().
246 getCheckerManager().runCheckersForPostStmt(Dst, Tmp, BE, *this);
249 void ExprEngine::VisitCast(const CastExpr *CastE, const Expr *Ex,
250 ExplodedNode *Pred, ExplodedNodeSet &Dst) {
252 ExplodedNodeSet dstPreStmt;
253 getCheckerManager().runCheckersForPreStmt(dstPreStmt, Pred, CastE, *this);
255 if (CastE->getCastKind() == CK_LValueToRValue) {
256 for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end();
258 ExplodedNode *subExprNode = *I;
259 ProgramStateRef state = subExprNode->getState();
260 const LocationContext *LCtx = subExprNode->getLocationContext();
261 evalLoad(Dst, CastE, CastE, subExprNode, state, state->getSVal(Ex, LCtx));
267 QualType T = CastE->getType();
268 QualType ExTy = Ex->getType();
270 if (const ExplicitCastExpr *ExCast=dyn_cast_or_null<ExplicitCastExpr>(CastE))
271 T = ExCast->getTypeAsWritten();
273 StmtNodeBuilder Bldr(dstPreStmt, Dst, *currBldrCtx);
274 for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end();
278 ProgramStateRef state = Pred->getState();
279 const LocationContext *LCtx = Pred->getLocationContext();
281 switch (CastE->getCastKind()) {
282 case CK_LValueToRValue:
283 llvm_unreachable("LValueToRValue casts handled earlier.");
286 // The analyzer doesn't do anything special with these casts,
287 // since it understands retain/release semantics already.
288 case CK_ARCProduceObject:
289 case CK_ARCConsumeObject:
290 case CK_ARCReclaimReturnedObject:
291 case CK_ARCExtendBlockObject: // Fall-through.
292 case CK_CopyAndAutoreleaseBlockObject:
293 // The analyser can ignore atomic casts for now, although some future
294 // checkers may want to make certain that you're not modifying the same
295 // value through atomic and nonatomic pointers.
296 case CK_AtomicToNonAtomic:
297 case CK_NonAtomicToAtomic:
300 case CK_ConstructorConversion:
301 case CK_UserDefinedConversion:
302 case CK_FunctionToPointerDecay:
303 case CK_BuiltinFnToFnPtr: {
304 // Copy the SVal of Ex to CastE.
305 ProgramStateRef state = Pred->getState();
306 const LocationContext *LCtx = Pred->getLocationContext();
307 SVal V = state->getSVal(Ex, LCtx);
308 state = state->BindExpr(CastE, LCtx, V);
309 Bldr.generateNode(CastE, Pred, state);
312 case CK_MemberPointerToBoolean:
313 // FIXME: For now, member pointers are represented by void *.
316 case CK_ArrayToPointerDecay:
318 case CK_AddressSpaceConversion:
319 case CK_IntegralCast:
320 case CK_NullToPointer:
321 case CK_IntegralToPointer:
322 case CK_PointerToIntegral:
323 case CK_PointerToBoolean:
324 case CK_IntegralToBoolean:
325 case CK_IntegralToFloating:
326 case CK_FloatingToIntegral:
327 case CK_FloatingToBoolean:
328 case CK_FloatingCast:
329 case CK_FloatingRealToComplex:
330 case CK_FloatingComplexToReal:
331 case CK_FloatingComplexToBoolean:
332 case CK_FloatingComplexCast:
333 case CK_FloatingComplexToIntegralComplex:
334 case CK_IntegralRealToComplex:
335 case CK_IntegralComplexToReal:
336 case CK_IntegralComplexToBoolean:
337 case CK_IntegralComplexCast:
338 case CK_IntegralComplexToFloatingComplex:
339 case CK_CPointerToObjCPointerCast:
340 case CK_BlockPointerToObjCPointerCast:
341 case CK_AnyPointerToBlockPointerCast:
342 case CK_ObjCObjectLValueCast:
343 case CK_ZeroToOCLEvent:
344 case CK_LValueBitCast: {
345 // Delegate to SValBuilder to process.
346 SVal V = state->getSVal(Ex, LCtx);
347 V = svalBuilder.evalCast(V, T, ExTy);
348 state = state->BindExpr(CastE, LCtx, V);
349 Bldr.generateNode(CastE, Pred, state);
352 case CK_DerivedToBase:
353 case CK_UncheckedDerivedToBase: {
354 // For DerivedToBase cast, delegate to the store manager.
355 SVal val = state->getSVal(Ex, LCtx);
356 val = getStoreManager().evalDerivedToBase(val, CastE);
357 state = state->BindExpr(CastE, LCtx, val);
358 Bldr.generateNode(CastE, Pred, state);
361 // Handle C++ dyn_cast.
363 SVal val = state->getSVal(Ex, LCtx);
365 // Compute the type of the result.
366 QualType resultType = CastE->getType();
367 if (CastE->isGLValue())
368 resultType = getContext().getPointerType(resultType);
372 // Check if the value being cast evaluates to 0.
373 if (val.isZeroConstant())
375 // Else, evaluate the cast.
377 val = getStoreManager().evalDynamicCast(val, T, Failed);
380 if (T->isReferenceType()) {
381 // A bad_cast exception is thrown if input value is a reference.
382 // Currently, we model this, by generating a sink.
383 Bldr.generateSink(CastE, Pred, state);
386 // If the cast fails on a pointer, bind to 0.
387 state = state->BindExpr(CastE, LCtx, svalBuilder.makeNull());
390 // If we don't know if the cast succeeded, conjure a new symbol.
391 if (val.isUnknown()) {
392 DefinedOrUnknownSVal NewSym =
393 svalBuilder.conjureSymbolVal(nullptr, CastE, LCtx, resultType,
394 currBldrCtx->blockCount());
395 state = state->BindExpr(CastE, LCtx, NewSym);
397 // Else, bind to the derived region value.
398 state = state->BindExpr(CastE, LCtx, val);
400 Bldr.generateNode(CastE, Pred, state);
403 case CK_NullToMemberPointer: {
404 // FIXME: For now, member pointers are represented by void *.
405 SVal V = svalBuilder.makeNull();
406 state = state->BindExpr(CastE, LCtx, V);
407 Bldr.generateNode(CastE, Pred, state);
410 // Various C++ casts that are not handled yet.
412 case CK_BaseToDerived:
413 case CK_BaseToDerivedMemberPointer:
414 case CK_DerivedToBaseMemberPointer:
415 case CK_ReinterpretMemberPointer:
416 case CK_VectorSplat: {
417 // Recover some path-sensitivty by conjuring a new value.
418 QualType resultType = CastE->getType();
419 if (CastE->isGLValue())
420 resultType = getContext().getPointerType(resultType);
421 SVal result = svalBuilder.conjureSymbolVal(nullptr, CastE, LCtx,
423 currBldrCtx->blockCount());
424 state = state->BindExpr(CastE, LCtx, result);
425 Bldr.generateNode(CastE, Pred, state);
432 void ExprEngine::VisitCompoundLiteralExpr(const CompoundLiteralExpr *CL,
434 ExplodedNodeSet &Dst) {
435 StmtNodeBuilder B(Pred, Dst, *currBldrCtx);
437 ProgramStateRef State = Pred->getState();
438 const LocationContext *LCtx = Pred->getLocationContext();
440 const Expr *Init = CL->getInitializer();
441 SVal V = State->getSVal(CL->getInitializer(), LCtx);
443 if (isa<CXXConstructExpr>(Init)) {
444 // No work needed. Just pass the value up to this expression.
446 assert(isa<InitListExpr>(Init));
447 Loc CLLoc = State->getLValue(CL, LCtx);
448 State = State->bindLoc(CLLoc, V);
450 // Compound literal expressions are a GNU extension in C++.
451 // Unlike in C, where CLs are lvalues, in C++ CLs are prvalues,
452 // and like temporary objects created by the functional notation T()
453 // CLs are destroyed at the end of the containing full-expression.
454 // HOWEVER, an rvalue of array type is not something the analyzer can
455 // reason about, since we expect all regions to be wrapped in Locs.
456 // So we treat array CLs as lvalues as well, knowing that they will decay
457 // to pointers as soon as they are used.
458 if (CL->isGLValue() || CL->getType()->isArrayType())
462 B.generateNode(CL, Pred, State->BindExpr(CL, LCtx, V));
465 void ExprEngine::VisitDeclStmt(const DeclStmt *DS, ExplodedNode *Pred,
466 ExplodedNodeSet &Dst) {
467 // Assumption: The CFG has one DeclStmt per Decl.
468 const VarDecl *VD = dyn_cast_or_null<VarDecl>(*DS->decl_begin());
471 //TODO:AZ: remove explicit insertion after refactoring is done.
476 // FIXME: all pre/post visits should eventually be handled by ::Visit().
477 ExplodedNodeSet dstPreVisit;
478 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, DS, *this);
480 ExplodedNodeSet dstEvaluated;
481 StmtNodeBuilder B(dstPreVisit, dstEvaluated, *currBldrCtx);
482 for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end();
484 ExplodedNode *N = *I;
485 ProgramStateRef state = N->getState();
486 const LocationContext *LC = N->getLocationContext();
488 // Decls without InitExpr are not initialized explicitly.
489 if (const Expr *InitEx = VD->getInit()) {
491 // Note in the state that the initialization has occurred.
492 ExplodedNode *UpdatedN = N;
493 SVal InitVal = state->getSVal(InitEx, LC);
495 assert(DS->isSingleDecl());
496 if (auto *CtorExpr = findDirectConstructorForCurrentCFGElement()) {
497 assert(InitEx->IgnoreImplicit() == CtorExpr);
499 // We constructed the object directly in the variable.
500 // No need to bind anything.
501 B.generateNode(DS, UpdatedN, state);
503 // We bound the temp obj region to the CXXConstructExpr. Now recover
504 // the lazy compound value when the variable is not a reference.
505 if (AMgr.getLangOpts().CPlusPlus && VD->getType()->isRecordType() &&
506 !VD->getType()->isReferenceType()) {
507 if (Optional<loc::MemRegionVal> M =
508 InitVal.getAs<loc::MemRegionVal>()) {
509 InitVal = state->getSVal(M->getRegion());
510 assert(InitVal.getAs<nonloc::LazyCompoundVal>());
514 // Recover some path-sensitivity if a scalar value evaluated to
516 if (InitVal.isUnknown()) {
517 QualType Ty = InitEx->getType();
518 if (InitEx->isGLValue()) {
519 Ty = getContext().getPointerType(Ty);
522 InitVal = svalBuilder.conjureSymbolVal(nullptr, InitEx, LC, Ty,
523 currBldrCtx->blockCount());
527 B.takeNodes(UpdatedN);
528 ExplodedNodeSet Dst2;
529 evalBind(Dst2, DS, UpdatedN, state->getLValue(VD, LC), InitVal, true);
534 B.generateNode(DS, N, state);
538 getCheckerManager().runCheckersForPostStmt(Dst, B.getResults(), DS, *this);
541 void ExprEngine::VisitLogicalExpr(const BinaryOperator* B, ExplodedNode *Pred,
542 ExplodedNodeSet &Dst) {
543 assert(B->getOpcode() == BO_LAnd ||
544 B->getOpcode() == BO_LOr);
546 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx);
547 ProgramStateRef state = Pred->getState();
549 ExplodedNode *N = Pred;
550 while (!N->getLocation().getAs<BlockEntrance>()) {
551 ProgramPoint P = N->getLocation();
552 assert(P.getAs<PreStmt>()|| P.getAs<PreStmtPurgeDeadSymbols>());
554 assert(N->pred_size() == 1);
555 N = *N->pred_begin();
557 assert(N->pred_size() == 1);
558 N = *N->pred_begin();
559 BlockEdge BE = N->getLocation().castAs<BlockEdge>();
562 // Determine the value of the expression by introspecting how we
563 // got this location in the CFG. This requires looking at the previous
564 // block we were in and what kind of control-flow transfer was involved.
565 const CFGBlock *SrcBlock = BE.getSrc();
566 // The only terminator (if there is one) that makes sense is a logical op.
567 CFGTerminator T = SrcBlock->getTerminator();
568 if (const BinaryOperator *Term = cast_or_null<BinaryOperator>(T.getStmt())) {
570 assert(Term->isLogicalOp());
571 assert(SrcBlock->succ_size() == 2);
572 // Did we take the true or false branch?
573 unsigned constant = (*SrcBlock->succ_begin() == BE.getDst()) ? 1 : 0;
574 X = svalBuilder.makeIntVal(constant, B->getType());
577 // If there is no terminator, by construction the last statement
578 // in SrcBlock is the value of the enclosing expression.
579 // However, we still need to constrain that value to be 0 or 1.
580 assert(!SrcBlock->empty());
581 CFGStmt Elem = SrcBlock->rbegin()->castAs<CFGStmt>();
582 const Expr *RHS = cast<Expr>(Elem.getStmt());
583 SVal RHSVal = N->getState()->getSVal(RHS, Pred->getLocationContext());
585 if (RHSVal.isUndef()) {
588 DefinedOrUnknownSVal DefinedRHS = RHSVal.castAs<DefinedOrUnknownSVal>();
589 ProgramStateRef StTrue, StFalse;
590 std::tie(StTrue, StFalse) = N->getState()->assume(DefinedRHS);
593 // We can't constrain the value to 0 or 1.
594 // The best we can do is a cast.
595 X = getSValBuilder().evalCast(RHSVal, B->getType(), RHS->getType());
597 // The value is known to be true.
598 X = getSValBuilder().makeIntVal(1, B->getType());
601 // The value is known to be false.
602 assert(StFalse && "Infeasible path!");
603 X = getSValBuilder().makeIntVal(0, B->getType());
607 Bldr.generateNode(B, Pred, state->BindExpr(B, Pred->getLocationContext(), X));
610 void ExprEngine::VisitInitListExpr(const InitListExpr *IE,
612 ExplodedNodeSet &Dst) {
613 StmtNodeBuilder B(Pred, Dst, *currBldrCtx);
615 ProgramStateRef state = Pred->getState();
616 const LocationContext *LCtx = Pred->getLocationContext();
617 QualType T = getContext().getCanonicalType(IE->getType());
618 unsigned NumInitElements = IE->getNumInits();
620 if (!IE->isGLValue() &&
621 (T->isArrayType() || T->isRecordType() || T->isVectorType() ||
622 T->isAnyComplexType())) {
623 llvm::ImmutableList<SVal> vals = getBasicVals().getEmptySValList();
625 // Handle base case where the initializer has no elements.
626 // e.g: static int* myArray[] = {};
627 if (NumInitElements == 0) {
628 SVal V = svalBuilder.makeCompoundVal(T, vals);
629 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V));
633 for (InitListExpr::const_reverse_iterator it = IE->rbegin(),
634 ei = IE->rend(); it != ei; ++it) {
635 SVal V = state->getSVal(cast<Expr>(*it), LCtx);
636 vals = getBasicVals().consVals(V, vals);
639 B.generateNode(IE, Pred,
640 state->BindExpr(IE, LCtx,
641 svalBuilder.makeCompoundVal(T, vals)));
645 // Handle scalars: int{5} and int{} and GLvalues.
646 // Note, if the InitListExpr is a GLvalue, it means that there is an address
647 // representing it, so it must have a single init element.
648 assert(NumInitElements <= 1);
651 if (NumInitElements == 0)
652 V = getSValBuilder().makeZeroVal(T);
654 V = state->getSVal(IE->getInit(0), LCtx);
656 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V));
659 void ExprEngine::VisitGuardedExpr(const Expr *Ex,
663 ExplodedNodeSet &Dst) {
666 StmtNodeBuilder B(Pred, Dst, *currBldrCtx);
667 ProgramStateRef state = Pred->getState();
668 const LocationContext *LCtx = Pred->getLocationContext();
669 const CFGBlock *SrcBlock = nullptr;
671 // Find the predecessor block.
672 ProgramStateRef SrcState = state;
673 for (const ExplodedNode *N = Pred ; N ; N = *N->pred_begin()) {
674 ProgramPoint PP = N->getLocation();
675 if (PP.getAs<PreStmtPurgeDeadSymbols>() || PP.getAs<BlockEntrance>()) {
676 assert(N->pred_size() == 1);
679 SrcBlock = PP.castAs<BlockEdge>().getSrc();
680 SrcState = N->getState();
684 assert(SrcBlock && "missing function entry");
686 // Find the last expression in the predecessor block. That is the
687 // expression that is used for the value of the ternary expression.
688 bool hasValue = false;
691 for (CFGElement CE : llvm::reverse(*SrcBlock)) {
692 if (Optional<CFGStmt> CS = CE.getAs<CFGStmt>()) {
693 const Expr *ValEx = cast<Expr>(CS->getStmt());
694 ValEx = ValEx->IgnoreParens();
696 // For GNU extension '?:' operator, the left hand side will be an
697 // OpaqueValueExpr, so get the underlying expression.
698 if (const OpaqueValueExpr *OpaqueEx = dyn_cast<OpaqueValueExpr>(L))
699 L = OpaqueEx->getSourceExpr();
701 // If the last expression in the predecessor block matches true or false
702 // subexpression, get its the value.
703 if (ValEx == L->IgnoreParens() || ValEx == R->IgnoreParens()) {
705 V = SrcState->getSVal(ValEx, LCtx);
712 V = svalBuilder.conjureSymbolVal(nullptr, Ex, LCtx,
713 currBldrCtx->blockCount());
715 // Generate a new node with the binding from the appropriate path.
716 B.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, V, true));
720 VisitOffsetOfExpr(const OffsetOfExpr *OOE,
721 ExplodedNode *Pred, ExplodedNodeSet &Dst) {
722 StmtNodeBuilder B(Pred, Dst, *currBldrCtx);
724 if (OOE->EvaluateAsInt(IV, getContext())) {
725 assert(IV.getBitWidth() == getContext().getTypeSize(OOE->getType()));
726 assert(OOE->getType()->isBuiltinType());
727 assert(OOE->getType()->getAs<BuiltinType>()->isInteger());
728 assert(IV.isSigned() == OOE->getType()->isSignedIntegerType());
729 SVal X = svalBuilder.makeIntVal(IV);
730 B.generateNode(OOE, Pred,
731 Pred->getState()->BindExpr(OOE, Pred->getLocationContext(),
734 // FIXME: Handle the case where __builtin_offsetof is not a constant.
739 VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *Ex,
741 ExplodedNodeSet &Dst) {
742 // FIXME: Prechecks eventually go in ::Visit().
743 ExplodedNodeSet CheckedSet;
744 getCheckerManager().runCheckersForPreStmt(CheckedSet, Pred, Ex, *this);
746 ExplodedNodeSet EvalSet;
747 StmtNodeBuilder Bldr(CheckedSet, EvalSet, *currBldrCtx);
749 QualType T = Ex->getTypeOfArgument();
751 for (ExplodedNodeSet::iterator I = CheckedSet.begin(), E = CheckedSet.end();
753 if (Ex->getKind() == UETT_SizeOf) {
754 if (!T->isIncompleteType() && !T->isConstantSizeType()) {
755 assert(T->isVariableArrayType() && "Unknown non-constant-sized type.");
757 // FIXME: Add support for VLA type arguments and VLA expressions.
758 // When that happens, we should probably refactor VLASizeChecker's code.
760 } else if (T->getAs<ObjCObjectType>()) {
761 // Some code tries to take the sizeof an ObjCObjectType, relying that
762 // the compiler has laid out its representation. Just report Unknown
768 APSInt Value = Ex->EvaluateKnownConstInt(getContext());
769 CharUnits amt = CharUnits::fromQuantity(Value.getZExtValue());
771 ProgramStateRef state = (*I)->getState();
772 state = state->BindExpr(Ex, (*I)->getLocationContext(),
773 svalBuilder.makeIntVal(amt.getQuantity(),
775 Bldr.generateNode(Ex, *I, state);
778 getCheckerManager().runCheckersForPostStmt(Dst, EvalSet, Ex, *this);
781 void ExprEngine::VisitUnaryOperator(const UnaryOperator* U,
783 ExplodedNodeSet &Dst) {
784 // FIXME: Prechecks eventually go in ::Visit().
785 ExplodedNodeSet CheckedSet;
786 getCheckerManager().runCheckersForPreStmt(CheckedSet, Pred, U, *this);
788 ExplodedNodeSet EvalSet;
789 StmtNodeBuilder Bldr(CheckedSet, EvalSet, *currBldrCtx);
791 for (ExplodedNodeSet::iterator I = CheckedSet.begin(), E = CheckedSet.end();
793 switch (U->getOpcode()) {
797 VisitIncrementDecrementOperator(U, *I, Tmp);
802 const Expr *Ex = U->getSubExpr()->IgnoreParens();
804 // FIXME: We don't have complex SValues yet.
805 if (Ex->getType()->isAnyComplexType()) {
806 // Just report "Unknown."
810 // For all other types, UO_Real is an identity operation.
811 assert (U->getType() == Ex->getType());
812 ProgramStateRef state = (*I)->getState();
813 const LocationContext *LCtx = (*I)->getLocationContext();
814 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx,
815 state->getSVal(Ex, LCtx)));
820 const Expr *Ex = U->getSubExpr()->IgnoreParens();
821 // FIXME: We don't have complex SValues yet.
822 if (Ex->getType()->isAnyComplexType()) {
823 // Just report "Unknown."
826 // For all other types, UO_Imag returns 0.
827 ProgramStateRef state = (*I)->getState();
828 const LocationContext *LCtx = (*I)->getLocationContext();
829 SVal X = svalBuilder.makeZeroVal(Ex->getType());
830 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, X));
835 assert(!U->isGLValue());
840 // FIXME: We can probably just have some magic in Environment::getSVal()
841 // that propagates values, instead of creating a new node here.
843 // Unary "+" is a no-op, similar to a parentheses. We still have places
844 // where it may be a block-level expression, so we need to
845 // generate an extra node that just propagates the value of the
847 const Expr *Ex = U->getSubExpr()->IgnoreParens();
848 ProgramStateRef state = (*I)->getState();
849 const LocationContext *LCtx = (*I)->getLocationContext();
850 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx,
851 state->getSVal(Ex, LCtx)));
858 assert (!U->isGLValue());
859 const Expr *Ex = U->getSubExpr()->IgnoreParens();
860 ProgramStateRef state = (*I)->getState();
861 const LocationContext *LCtx = (*I)->getLocationContext();
863 // Get the value of the subexpression.
864 SVal V = state->getSVal(Ex, LCtx);
866 if (V.isUnknownOrUndef()) {
867 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, V));
871 switch (U->getOpcode()) {
873 llvm_unreachable("Invalid Opcode.");
875 // FIXME: Do we need to handle promotions?
876 state = state->BindExpr(U, LCtx, evalComplement(V.castAs<NonLoc>()));
879 // FIXME: Do we need to handle promotions?
880 state = state->BindExpr(U, LCtx, evalMinus(V.castAs<NonLoc>()));
883 // C99 6.5.3.3: "The expression !E is equivalent to (0==E)."
885 // Note: technically we do "E == 0", but this is the same in the
886 // transfer functions as "0 == E".
888 if (Optional<Loc> LV = V.getAs<Loc>()) {
889 Loc X = svalBuilder.makeNull();
890 Result = evalBinOp(state, BO_EQ, *LV, X, U->getType());
892 else if (Ex->getType()->isFloatingType()) {
893 // FIXME: handle floating point types.
894 Result = UnknownVal();
896 nonloc::ConcreteInt X(getBasicVals().getValue(0, Ex->getType()));
897 Result = evalBinOp(state, BO_EQ, V.castAs<NonLoc>(), X,
901 state = state->BindExpr(U, LCtx, Result);
904 Bldr.generateNode(U, *I, state);
910 getCheckerManager().runCheckersForPostStmt(Dst, EvalSet, U, *this);
913 void ExprEngine::VisitIncrementDecrementOperator(const UnaryOperator* U,
915 ExplodedNodeSet &Dst) {
916 // Handle ++ and -- (both pre- and post-increment).
917 assert (U->isIncrementDecrementOp());
918 const Expr *Ex = U->getSubExpr()->IgnoreParens();
920 const LocationContext *LCtx = Pred->getLocationContext();
921 ProgramStateRef state = Pred->getState();
922 SVal loc = state->getSVal(Ex, LCtx);
926 evalLoad(Tmp, U, Ex, Pred, state, loc);
928 ExplodedNodeSet Dst2;
929 StmtNodeBuilder Bldr(Tmp, Dst2, *currBldrCtx);
930 for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end();I!=E;++I) {
932 state = (*I)->getState();
933 assert(LCtx == (*I)->getLocationContext());
934 SVal V2_untested = state->getSVal(Ex, LCtx);
936 // Propagate unknown and undefined values.
937 if (V2_untested.isUnknownOrUndef()) {
938 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, V2_untested));
941 DefinedSVal V2 = V2_untested.castAs<DefinedSVal>();
943 // Handle all other values.
944 BinaryOperator::Opcode Op = U->isIncrementOp() ? BO_Add : BO_Sub;
946 // If the UnaryOperator has non-location type, use its type to create the
947 // constant value. If the UnaryOperator has location type, create the
948 // constant with int type and pointer width.
951 if (U->getType()->isAnyPointerType())
952 RHS = svalBuilder.makeArrayIndex(1);
953 else if (U->getType()->isIntegralOrEnumerationType())
954 RHS = svalBuilder.makeIntVal(1, U->getType());
958 SVal Result = evalBinOp(state, Op, V2, RHS, U->getType());
960 // Conjure a new symbol if necessary to recover precision.
961 if (Result.isUnknown()){
962 DefinedOrUnknownSVal SymVal =
963 svalBuilder.conjureSymbolVal(nullptr, Ex, LCtx,
964 currBldrCtx->blockCount());
967 // If the value is a location, ++/-- should always preserve
968 // non-nullness. Check if the original value was non-null, and if so
969 // propagate that constraint.
970 if (Loc::isLocType(U->getType())) {
971 DefinedOrUnknownSVal Constraint =
972 svalBuilder.evalEQ(state, V2,svalBuilder.makeZeroVal(U->getType()));
974 if (!state->assume(Constraint, true)) {
975 // It isn't feasible for the original value to be null.
976 // Propagate this constraint.
977 Constraint = svalBuilder.evalEQ(state, SymVal,
978 svalBuilder.makeZeroVal(U->getType()));
981 state = state->assume(Constraint, false);
987 // Since the lvalue-to-rvalue conversion is explicit in the AST,
988 // we bind an l-value if the operator is prefix and an lvalue (in C++).
990 state = state->BindExpr(U, LCtx, loc);
992 state = state->BindExpr(U, LCtx, U->isPostfix() ? V2 : Result);
994 // Perform the store.
996 ExplodedNodeSet Dst3;
997 evalStore(Dst3, U, U, *I, state, loc, Result);