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/AST/DeclCXX.h"
16 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
17 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
19 using namespace clang;
23 /// \brief Optionally conjure and return a symbol for offset when processing
24 /// an expression \p Expression.
25 /// If \p Other is a location, conjure a symbol for \p Symbol
26 /// (offset) if it is unknown so that memory arithmetic always
27 /// results in an ElementRegion.
28 /// \p Count The number of times the current basic block was visited.
29 static SVal conjureOffsetSymbolOnLocation(
30 SVal Symbol, SVal Other, Expr* Expression, SValBuilder &svalBuilder,
31 unsigned Count, const LocationContext *LCtx) {
32 QualType Ty = Expression->getType();
33 if (Other.getAs<Loc>() &&
34 Ty->isIntegralOrEnumerationType() &&
36 return svalBuilder.conjureSymbolVal(Expression, LCtx, Ty, Count);
41 void ExprEngine::VisitBinaryOperator(const BinaryOperator* B,
43 ExplodedNodeSet &Dst) {
45 Expr *LHS = B->getLHS()->IgnoreParens();
46 Expr *RHS = B->getRHS()->IgnoreParens();
48 // FIXME: Prechecks eventually go in ::Visit().
49 ExplodedNodeSet CheckedSet;
51 getCheckerManager().runCheckersForPreStmt(CheckedSet, Pred, B, *this);
53 // With both the LHS and RHS evaluated, process the operation itself.
54 for (ExplodedNodeSet::iterator it=CheckedSet.begin(), ei=CheckedSet.end();
57 ProgramStateRef state = (*it)->getState();
58 const LocationContext *LCtx = (*it)->getLocationContext();
59 SVal LeftV = state->getSVal(LHS, LCtx);
60 SVal RightV = state->getSVal(RHS, LCtx);
62 BinaryOperator::Opcode Op = B->getOpcode();
64 if (Op == BO_Assign) {
65 // EXPERIMENTAL: "Conjured" symbols.
66 // FIXME: Handle structs.
67 if (RightV.isUnknown()) {
68 unsigned Count = currBldrCtx->blockCount();
69 RightV = svalBuilder.conjureSymbolVal(nullptr, B->getRHS(), LCtx,
72 // Simulate the effects of a "store": bind the value of the RHS
73 // to the L-Value represented by the LHS.
74 SVal ExprVal = B->isGLValue() ? LeftV : RightV;
75 evalStore(Tmp2, B, LHS, *it, state->BindExpr(B, LCtx, ExprVal),
80 if (!B->isAssignmentOp()) {
81 StmtNodeBuilder Bldr(*it, Tmp2, *currBldrCtx);
83 if (B->isAdditiveOp()) {
84 // TODO: This can be removed after we enable history tracking with
86 unsigned Count = currBldrCtx->blockCount();
87 RightV = conjureOffsetSymbolOnLocation(
88 RightV, LeftV, RHS, svalBuilder, Count, LCtx);
89 LeftV = conjureOffsetSymbolOnLocation(
90 LeftV, RightV, LHS, svalBuilder, Count, LCtx);
93 // Although we don't yet model pointers-to-members, we do need to make
94 // sure that the members of temporaries have a valid 'this' pointer for
96 if (B->getOpcode() == BO_PtrMemD)
97 state = createTemporaryRegionIfNeeded(state, LCtx, LHS);
99 // Process non-assignments except commas or short-circuited
100 // logical expressions (LAnd and LOr).
101 SVal Result = evalBinOp(state, Op, LeftV, RightV, B->getType());
102 if (!Result.isUnknown()) {
103 state = state->BindExpr(B, LCtx, Result);
106 Bldr.generateNode(B, *it, state);
110 assert (B->isCompoundAssignmentOp());
114 llvm_unreachable("Invalid opcode for compound assignment.");
115 case BO_MulAssign: Op = BO_Mul; break;
116 case BO_DivAssign: Op = BO_Div; break;
117 case BO_RemAssign: Op = BO_Rem; break;
118 case BO_AddAssign: Op = BO_Add; break;
119 case BO_SubAssign: Op = BO_Sub; break;
120 case BO_ShlAssign: Op = BO_Shl; break;
121 case BO_ShrAssign: Op = BO_Shr; break;
122 case BO_AndAssign: Op = BO_And; break;
123 case BO_XorAssign: Op = BO_Xor; break;
124 case BO_OrAssign: Op = BO_Or; break;
127 // Perform a load (the LHS). This performs the checks for
128 // null dereferences, and so on.
130 SVal location = LeftV;
131 evalLoad(Tmp, B, LHS, *it, state, location);
133 for (ExplodedNodeSet::iterator I = Tmp.begin(), E = Tmp.end(); I != E;
136 state = (*I)->getState();
137 const LocationContext *LCtx = (*I)->getLocationContext();
138 SVal V = state->getSVal(LHS, LCtx);
140 // Get the computation type.
142 cast<CompoundAssignOperator>(B)->getComputationResultType();
143 CTy = getContext().getCanonicalType(CTy);
146 cast<CompoundAssignOperator>(B)->getComputationLHSType();
147 CLHSTy = getContext().getCanonicalType(CLHSTy);
149 QualType LTy = getContext().getCanonicalType(LHS->getType());
152 V = svalBuilder.evalCast(V, CLHSTy, LTy);
154 // Compute the result of the operation.
155 SVal Result = svalBuilder.evalCast(evalBinOp(state, Op, V, RightV, CTy),
158 // EXPERIMENTAL: "Conjured" symbols.
159 // FIXME: Handle structs.
163 if (Result.isUnknown()) {
164 // The symbolic value is actually for the type of the left-hand side
165 // expression, not the computation type, as this is the value the
166 // LValue on the LHS will bind to.
167 LHSVal = svalBuilder.conjureSymbolVal(nullptr, B->getRHS(), LCtx, LTy,
168 currBldrCtx->blockCount());
169 // However, we need to convert the symbol to the computation type.
170 Result = svalBuilder.evalCast(LHSVal, CTy, LTy);
173 // The left-hand side may bind to a different value then the
175 LHSVal = svalBuilder.evalCast(Result, LTy, CTy);
178 // In C++, assignment and compound assignment operators return an
181 state = state->BindExpr(B, LCtx, location);
183 state = state->BindExpr(B, LCtx, Result);
185 evalStore(Tmp2, B, LHS, *I, state, location, LHSVal);
189 // FIXME: postvisits eventually go in ::Visit()
190 getCheckerManager().runCheckersForPostStmt(Dst, Tmp2, B, *this);
193 void ExprEngine::VisitBlockExpr(const BlockExpr *BE, ExplodedNode *Pred,
194 ExplodedNodeSet &Dst) {
196 CanQualType T = getContext().getCanonicalType(BE->getType());
198 const BlockDecl *BD = BE->getBlockDecl();
199 // Get the value of the block itself.
200 SVal V = svalBuilder.getBlockPointer(BD, T,
201 Pred->getLocationContext(),
202 currBldrCtx->blockCount());
204 ProgramStateRef State = Pred->getState();
206 // If we created a new MemRegion for the block, we should explicitly bind
207 // the captured variables.
208 if (const BlockDataRegion *BDR =
209 dyn_cast_or_null<BlockDataRegion>(V.getAsRegion())) {
211 BlockDataRegion::referenced_vars_iterator I = BDR->referenced_vars_begin(),
212 E = BDR->referenced_vars_end();
214 auto CI = BD->capture_begin();
215 auto CE = BD->capture_end();
216 for (; I != E; ++I) {
217 const VarRegion *capturedR = I.getCapturedRegion();
218 const VarRegion *originalR = I.getOriginalRegion();
220 // If the capture had a copy expression, use the result of evaluating
221 // that expression, otherwise use the original value.
222 // We rely on the invariant that the block declaration's capture variables
223 // are a prefix of the BlockDataRegion's referenced vars (which may include
224 // referenced globals, etc.) to enable fast lookup of the capture for a
225 // given referenced var.
226 const Expr *copyExpr = nullptr;
228 assert(CI->getVariable() == capturedR->getDecl());
229 copyExpr = CI->getCopyExpr();
233 if (capturedR != originalR) {
235 const LocationContext *LCtx = Pred->getLocationContext();
237 originalV = State->getSVal(copyExpr, LCtx);
239 originalV = State->getSVal(loc::MemRegionVal(originalR));
241 State = State->bindLoc(loc::MemRegionVal(capturedR), originalV, LCtx);
247 StmtNodeBuilder Bldr(Pred, Tmp, *currBldrCtx);
248 Bldr.generateNode(BE, Pred,
249 State->BindExpr(BE, Pred->getLocationContext(), V),
250 nullptr, ProgramPoint::PostLValueKind);
252 // FIXME: Move all post/pre visits to ::Visit().
253 getCheckerManager().runCheckersForPostStmt(Dst, Tmp, BE, *this);
256 ProgramStateRef ExprEngine::handleLValueBitCast(
257 ProgramStateRef state, const Expr* Ex, const LocationContext* LCtx,
258 QualType T, QualType ExTy, const CastExpr* CastE, StmtNodeBuilder& Bldr,
259 ExplodedNode* Pred) {
260 // Delegate to SValBuilder to process.
261 SVal V = state->getSVal(Ex, LCtx);
262 V = svalBuilder.evalCast(V, T, ExTy);
263 // Negate the result if we're treating the boolean as a signed i1
264 if (CastE->getCastKind() == CK_BooleanToSignedIntegral)
266 state = state->BindExpr(CastE, LCtx, V);
267 Bldr.generateNode(CastE, Pred, state);
272 ProgramStateRef ExprEngine::handleLVectorSplat(
273 ProgramStateRef state, const LocationContext* LCtx, const CastExpr* CastE,
274 StmtNodeBuilder &Bldr, ExplodedNode* Pred) {
275 // Recover some path sensitivity by conjuring a new value.
276 QualType resultType = CastE->getType();
277 if (CastE->isGLValue())
278 resultType = getContext().getPointerType(resultType);
279 SVal result = svalBuilder.conjureSymbolVal(nullptr, CastE, LCtx,
281 currBldrCtx->blockCount());
282 state = state->BindExpr(CastE, LCtx, result);
283 Bldr.generateNode(CastE, Pred, state);
288 void ExprEngine::VisitCast(const CastExpr *CastE, const Expr *Ex,
289 ExplodedNode *Pred, ExplodedNodeSet &Dst) {
291 ExplodedNodeSet dstPreStmt;
292 getCheckerManager().runCheckersForPreStmt(dstPreStmt, Pred, CastE, *this);
294 if (CastE->getCastKind() == CK_LValueToRValue) {
295 for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end();
297 ExplodedNode *subExprNode = *I;
298 ProgramStateRef state = subExprNode->getState();
299 const LocationContext *LCtx = subExprNode->getLocationContext();
300 evalLoad(Dst, CastE, CastE, subExprNode, state, state->getSVal(Ex, LCtx));
306 QualType T = CastE->getType();
307 QualType ExTy = Ex->getType();
309 if (const ExplicitCastExpr *ExCast=dyn_cast_or_null<ExplicitCastExpr>(CastE))
310 T = ExCast->getTypeAsWritten();
312 StmtNodeBuilder Bldr(dstPreStmt, Dst, *currBldrCtx);
313 for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end();
317 ProgramStateRef state = Pred->getState();
318 const LocationContext *LCtx = Pred->getLocationContext();
320 switch (CastE->getCastKind()) {
321 case CK_LValueToRValue:
322 llvm_unreachable("LValueToRValue casts handled earlier.");
325 // The analyzer doesn't do anything special with these casts,
326 // since it understands retain/release semantics already.
327 case CK_ARCProduceObject:
328 case CK_ARCConsumeObject:
329 case CK_ARCReclaimReturnedObject:
330 case CK_ARCExtendBlockObject: // Fall-through.
331 case CK_CopyAndAutoreleaseBlockObject:
332 // The analyser can ignore atomic casts for now, although some future
333 // checkers may want to make certain that you're not modifying the same
334 // value through atomic and nonatomic pointers.
335 case CK_AtomicToNonAtomic:
336 case CK_NonAtomicToAtomic:
339 case CK_ConstructorConversion:
340 case CK_UserDefinedConversion:
341 case CK_FunctionToPointerDecay:
342 case CK_BuiltinFnToFnPtr: {
343 // Copy the SVal of Ex to CastE.
344 ProgramStateRef state = Pred->getState();
345 const LocationContext *LCtx = Pred->getLocationContext();
346 SVal V = state->getSVal(Ex, LCtx);
347 state = state->BindExpr(CastE, LCtx, V);
348 Bldr.generateNode(CastE, Pred, state);
351 case CK_MemberPointerToBoolean:
352 case CK_PointerToBoolean: {
353 SVal V = state->getSVal(Ex, LCtx);
354 auto PTMSV = V.getAs<nonloc::PointerToMember>();
356 V = svalBuilder.makeTruthVal(!PTMSV->isNullMemberPointer(), ExTy);
357 if (V.isUndef() || PTMSV) {
358 state = state->BindExpr(CastE, LCtx, V);
359 Bldr.generateNode(CastE, Pred, state);
362 // Explicitly proceed with default handler for this case cascade.
364 handleLValueBitCast(state, Ex, LCtx, T, ExTy, CastE, Bldr, Pred);
368 case CK_ArrayToPointerDecay:
370 case CK_AddressSpaceConversion:
371 case CK_BooleanToSignedIntegral:
372 case CK_NullToPointer:
373 case CK_IntegralToPointer:
374 case CK_PointerToIntegral: {
375 SVal V = state->getSVal(Ex, LCtx);
376 if (V.getAs<nonloc::PointerToMember>()) {
377 state = state->BindExpr(CastE, LCtx, UnknownVal());
378 Bldr.generateNode(CastE, Pred, state);
381 // Explicitly proceed with default handler for this case cascade.
383 handleLValueBitCast(state, Ex, LCtx, T, ExTy, CastE, Bldr, Pred);
386 case CK_IntegralToBoolean:
387 case CK_IntegralToFloating:
388 case CK_FloatingToIntegral:
389 case CK_FloatingToBoolean:
390 case CK_FloatingCast:
391 case CK_FloatingRealToComplex:
392 case CK_FloatingComplexToReal:
393 case CK_FloatingComplexToBoolean:
394 case CK_FloatingComplexCast:
395 case CK_FloatingComplexToIntegralComplex:
396 case CK_IntegralRealToComplex:
397 case CK_IntegralComplexToReal:
398 case CK_IntegralComplexToBoolean:
399 case CK_IntegralComplexCast:
400 case CK_IntegralComplexToFloatingComplex:
401 case CK_CPointerToObjCPointerCast:
402 case CK_BlockPointerToObjCPointerCast:
403 case CK_AnyPointerToBlockPointerCast:
404 case CK_ObjCObjectLValueCast:
405 case CK_ZeroToOCLEvent:
406 case CK_ZeroToOCLQueue:
407 case CK_IntToOCLSampler:
408 case CK_LValueBitCast: {
410 handleLValueBitCast(state, Ex, LCtx, T, ExTy, CastE, Bldr, Pred);
413 case CK_IntegralCast: {
414 // Delegate to SValBuilder to process.
415 SVal V = state->getSVal(Ex, LCtx);
416 V = svalBuilder.evalIntegralCast(state, V, T, ExTy);
417 state = state->BindExpr(CastE, LCtx, V);
418 Bldr.generateNode(CastE, Pred, state);
421 case CK_DerivedToBase:
422 case CK_UncheckedDerivedToBase: {
423 // For DerivedToBase cast, delegate to the store manager.
424 SVal val = state->getSVal(Ex, LCtx);
425 val = getStoreManager().evalDerivedToBase(val, CastE);
426 state = state->BindExpr(CastE, LCtx, val);
427 Bldr.generateNode(CastE, Pred, state);
430 // Handle C++ dyn_cast.
432 SVal val = state->getSVal(Ex, LCtx);
434 // Compute the type of the result.
435 QualType resultType = CastE->getType();
436 if (CastE->isGLValue())
437 resultType = getContext().getPointerType(resultType);
441 // Check if the value being cast evaluates to 0.
442 if (val.isZeroConstant())
444 // Else, evaluate the cast.
446 val = getStoreManager().attemptDownCast(val, T, Failed);
449 if (T->isReferenceType()) {
450 // A bad_cast exception is thrown if input value is a reference.
451 // Currently, we model this, by generating a sink.
452 Bldr.generateSink(CastE, Pred, state);
455 // If the cast fails on a pointer, bind to 0.
456 state = state->BindExpr(CastE, LCtx, svalBuilder.makeNull());
459 // If we don't know if the cast succeeded, conjure a new symbol.
460 if (val.isUnknown()) {
461 DefinedOrUnknownSVal NewSym =
462 svalBuilder.conjureSymbolVal(nullptr, CastE, LCtx, resultType,
463 currBldrCtx->blockCount());
464 state = state->BindExpr(CastE, LCtx, NewSym);
466 // Else, bind to the derived region value.
467 state = state->BindExpr(CastE, LCtx, val);
469 Bldr.generateNode(CastE, Pred, state);
472 case CK_BaseToDerived: {
473 SVal val = state->getSVal(Ex, LCtx);
474 QualType resultType = CastE->getType();
475 if (CastE->isGLValue())
476 resultType = getContext().getPointerType(resultType);
480 if (!val.isConstant()) {
481 val = getStoreManager().attemptDownCast(val, T, Failed);
484 // Failed to cast or the result is unknown, fall back to conservative.
485 if (Failed || val.isUnknown()) {
487 svalBuilder.conjureSymbolVal(nullptr, CastE, LCtx, resultType,
488 currBldrCtx->blockCount());
490 state = state->BindExpr(CastE, LCtx, val);
491 Bldr.generateNode(CastE, Pred, state);
494 case CK_NullToMemberPointer: {
495 SVal V = svalBuilder.getMemberPointer(nullptr);
496 state = state->BindExpr(CastE, LCtx, V);
497 Bldr.generateNode(CastE, Pred, state);
500 case CK_DerivedToBaseMemberPointer:
501 case CK_BaseToDerivedMemberPointer:
502 case CK_ReinterpretMemberPointer: {
503 SVal V = state->getSVal(Ex, LCtx);
504 if (auto PTMSV = V.getAs<nonloc::PointerToMember>()) {
505 SVal CastedPTMSV = svalBuilder.makePointerToMember(
506 getBasicVals().accumCXXBase(
507 llvm::make_range<CastExpr::path_const_iterator>(
508 CastE->path_begin(), CastE->path_end()), *PTMSV));
509 state = state->BindExpr(CastE, LCtx, CastedPTMSV);
510 Bldr.generateNode(CastE, Pred, state);
513 // Explicitly proceed with default handler for this case cascade.
514 state = handleLVectorSplat(state, LCtx, CastE, Bldr, Pred);
517 // Various C++ casts that are not handled yet.
519 case CK_VectorSplat: {
520 state = handleLVectorSplat(state, LCtx, CastE, Bldr, Pred);
527 void ExprEngine::VisitCompoundLiteralExpr(const CompoundLiteralExpr *CL,
529 ExplodedNodeSet &Dst) {
530 StmtNodeBuilder B(Pred, Dst, *currBldrCtx);
532 ProgramStateRef State = Pred->getState();
533 const LocationContext *LCtx = Pred->getLocationContext();
535 const Expr *Init = CL->getInitializer();
536 SVal V = State->getSVal(CL->getInitializer(), LCtx);
538 if (isa<CXXConstructExpr>(Init) || isa<CXXStdInitializerListExpr>(Init)) {
539 // No work needed. Just pass the value up to this expression.
541 assert(isa<InitListExpr>(Init));
542 Loc CLLoc = State->getLValue(CL, LCtx);
543 State = State->bindLoc(CLLoc, V, LCtx);
549 B.generateNode(CL, Pred, State->BindExpr(CL, LCtx, V));
552 void ExprEngine::VisitDeclStmt(const DeclStmt *DS, ExplodedNode *Pred,
553 ExplodedNodeSet &Dst) {
554 // Assumption: The CFG has one DeclStmt per Decl.
555 const VarDecl *VD = dyn_cast_or_null<VarDecl>(*DS->decl_begin());
558 //TODO:AZ: remove explicit insertion after refactoring is done.
563 // FIXME: all pre/post visits should eventually be handled by ::Visit().
564 ExplodedNodeSet dstPreVisit;
565 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, DS, *this);
567 ExplodedNodeSet dstEvaluated;
568 StmtNodeBuilder B(dstPreVisit, dstEvaluated, *currBldrCtx);
569 for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end();
571 ExplodedNode *N = *I;
572 ProgramStateRef state = N->getState();
573 const LocationContext *LC = N->getLocationContext();
575 // Decls without InitExpr are not initialized explicitly.
576 if (const Expr *InitEx = VD->getInit()) {
578 // Note in the state that the initialization has occurred.
579 ExplodedNode *UpdatedN = N;
580 SVal InitVal = state->getSVal(InitEx, LC);
582 assert(DS->isSingleDecl());
583 if (auto *CtorExpr = findDirectConstructorForCurrentCFGElement()) {
584 assert(InitEx->IgnoreImplicit() == CtorExpr);
586 // We constructed the object directly in the variable.
587 // No need to bind anything.
588 B.generateNode(DS, UpdatedN, state);
590 // We bound the temp obj region to the CXXConstructExpr. Now recover
591 // the lazy compound value when the variable is not a reference.
592 if (AMgr.getLangOpts().CPlusPlus && VD->getType()->isRecordType() &&
593 !VD->getType()->isReferenceType()) {
594 if (Optional<loc::MemRegionVal> M =
595 InitVal.getAs<loc::MemRegionVal>()) {
596 InitVal = state->getSVal(M->getRegion());
597 assert(InitVal.getAs<nonloc::LazyCompoundVal>());
601 // Recover some path-sensitivity if a scalar value evaluated to
603 if (InitVal.isUnknown()) {
604 QualType Ty = InitEx->getType();
605 if (InitEx->isGLValue()) {
606 Ty = getContext().getPointerType(Ty);
609 InitVal = svalBuilder.conjureSymbolVal(nullptr, InitEx, LC, Ty,
610 currBldrCtx->blockCount());
614 B.takeNodes(UpdatedN);
615 ExplodedNodeSet Dst2;
616 evalBind(Dst2, DS, UpdatedN, state->getLValue(VD, LC), InitVal, true);
621 B.generateNode(DS, N, state);
625 getCheckerManager().runCheckersForPostStmt(Dst, B.getResults(), DS, *this);
628 void ExprEngine::VisitLogicalExpr(const BinaryOperator* B, ExplodedNode *Pred,
629 ExplodedNodeSet &Dst) {
630 assert(B->getOpcode() == BO_LAnd ||
631 B->getOpcode() == BO_LOr);
633 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx);
634 ProgramStateRef state = Pred->getState();
636 if (B->getType()->isVectorType()) {
637 // FIXME: We do not model vector arithmetic yet. When adding support for
638 // that, note that the CFG-based reasoning below does not apply, because
639 // logical operators on vectors are not short-circuit. Currently they are
640 // modeled as short-circuit in Clang CFG but this is incorrect.
641 // Do not set the value for the expression. It'd be UnknownVal by default.
642 Bldr.generateNode(B, Pred, state);
646 ExplodedNode *N = Pred;
647 while (!N->getLocation().getAs<BlockEntrance>()) {
648 ProgramPoint P = N->getLocation();
649 assert(P.getAs<PreStmt>()|| P.getAs<PreStmtPurgeDeadSymbols>());
651 assert(N->pred_size() == 1);
652 N = *N->pred_begin();
654 assert(N->pred_size() == 1);
655 N = *N->pred_begin();
656 BlockEdge BE = N->getLocation().castAs<BlockEdge>();
659 // Determine the value of the expression by introspecting how we
660 // got this location in the CFG. This requires looking at the previous
661 // block we were in and what kind of control-flow transfer was involved.
662 const CFGBlock *SrcBlock = BE.getSrc();
663 // The only terminator (if there is one) that makes sense is a logical op.
664 CFGTerminator T = SrcBlock->getTerminator();
665 if (const BinaryOperator *Term = cast_or_null<BinaryOperator>(T.getStmt())) {
667 assert(Term->isLogicalOp());
668 assert(SrcBlock->succ_size() == 2);
669 // Did we take the true or false branch?
670 unsigned constant = (*SrcBlock->succ_begin() == BE.getDst()) ? 1 : 0;
671 X = svalBuilder.makeIntVal(constant, B->getType());
674 // If there is no terminator, by construction the last statement
675 // in SrcBlock is the value of the enclosing expression.
676 // However, we still need to constrain that value to be 0 or 1.
677 assert(!SrcBlock->empty());
678 CFGStmt Elem = SrcBlock->rbegin()->castAs<CFGStmt>();
679 const Expr *RHS = cast<Expr>(Elem.getStmt());
680 SVal RHSVal = N->getState()->getSVal(RHS, Pred->getLocationContext());
682 if (RHSVal.isUndef()) {
685 // We evaluate "RHSVal != 0" expression which result in 0 if the value is
686 // known to be false, 1 if the value is known to be true and a new symbol
687 // when the assumption is unknown.
688 nonloc::ConcreteInt Zero(getBasicVals().getValue(0, B->getType()));
689 X = evalBinOp(N->getState(), BO_NE,
690 svalBuilder.evalCast(RHSVal, B->getType(), RHS->getType()),
694 Bldr.generateNode(B, Pred, state->BindExpr(B, Pred->getLocationContext(), X));
697 void ExprEngine::VisitInitListExpr(const InitListExpr *IE,
699 ExplodedNodeSet &Dst) {
700 StmtNodeBuilder B(Pred, Dst, *currBldrCtx);
702 ProgramStateRef state = Pred->getState();
703 const LocationContext *LCtx = Pred->getLocationContext();
704 QualType T = getContext().getCanonicalType(IE->getType());
705 unsigned NumInitElements = IE->getNumInits();
707 if (!IE->isGLValue() &&
708 (T->isArrayType() || T->isRecordType() || T->isVectorType() ||
709 T->isAnyComplexType())) {
710 llvm::ImmutableList<SVal> vals = getBasicVals().getEmptySValList();
712 // Handle base case where the initializer has no elements.
713 // e.g: static int* myArray[] = {};
714 if (NumInitElements == 0) {
715 SVal V = svalBuilder.makeCompoundVal(T, vals);
716 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V));
720 for (InitListExpr::const_reverse_iterator it = IE->rbegin(),
721 ei = IE->rend(); it != ei; ++it) {
722 SVal V = state->getSVal(cast<Expr>(*it), LCtx);
723 vals = getBasicVals().prependSVal(V, vals);
726 B.generateNode(IE, Pred,
727 state->BindExpr(IE, LCtx,
728 svalBuilder.makeCompoundVal(T, vals)));
732 // Handle scalars: int{5} and int{} and GLvalues.
733 // Note, if the InitListExpr is a GLvalue, it means that there is an address
734 // representing it, so it must have a single init element.
735 assert(NumInitElements <= 1);
738 if (NumInitElements == 0)
739 V = getSValBuilder().makeZeroVal(T);
741 V = state->getSVal(IE->getInit(0), LCtx);
743 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V));
746 void ExprEngine::VisitGuardedExpr(const Expr *Ex,
750 ExplodedNodeSet &Dst) {
753 StmtNodeBuilder B(Pred, Dst, *currBldrCtx);
754 ProgramStateRef state = Pred->getState();
755 const LocationContext *LCtx = Pred->getLocationContext();
756 const CFGBlock *SrcBlock = nullptr;
758 // Find the predecessor block.
759 ProgramStateRef SrcState = state;
760 for (const ExplodedNode *N = Pred ; N ; N = *N->pred_begin()) {
761 ProgramPoint PP = N->getLocation();
762 if (PP.getAs<PreStmtPurgeDeadSymbols>() || PP.getAs<BlockEntrance>()) {
763 assert(N->pred_size() == 1);
766 SrcBlock = PP.castAs<BlockEdge>().getSrc();
767 SrcState = N->getState();
771 assert(SrcBlock && "missing function entry");
773 // Find the last expression in the predecessor block. That is the
774 // expression that is used for the value of the ternary expression.
775 bool hasValue = false;
778 for (CFGElement CE : llvm::reverse(*SrcBlock)) {
779 if (Optional<CFGStmt> CS = CE.getAs<CFGStmt>()) {
780 const Expr *ValEx = cast<Expr>(CS->getStmt());
781 ValEx = ValEx->IgnoreParens();
783 // For GNU extension '?:' operator, the left hand side will be an
784 // OpaqueValueExpr, so get the underlying expression.
785 if (const OpaqueValueExpr *OpaqueEx = dyn_cast<OpaqueValueExpr>(L))
786 L = OpaqueEx->getSourceExpr();
788 // If the last expression in the predecessor block matches true or false
789 // subexpression, get its the value.
790 if (ValEx == L->IgnoreParens() || ValEx == R->IgnoreParens()) {
792 V = SrcState->getSVal(ValEx, LCtx);
799 V = svalBuilder.conjureSymbolVal(nullptr, Ex, LCtx,
800 currBldrCtx->blockCount());
802 // Generate a new node with the binding from the appropriate path.
803 B.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, V, true));
807 VisitOffsetOfExpr(const OffsetOfExpr *OOE,
808 ExplodedNode *Pred, ExplodedNodeSet &Dst) {
809 StmtNodeBuilder B(Pred, Dst, *currBldrCtx);
811 if (OOE->EvaluateAsInt(IV, getContext())) {
812 assert(IV.getBitWidth() == getContext().getTypeSize(OOE->getType()));
813 assert(OOE->getType()->isBuiltinType());
814 assert(OOE->getType()->getAs<BuiltinType>()->isInteger());
815 assert(IV.isSigned() == OOE->getType()->isSignedIntegerType());
816 SVal X = svalBuilder.makeIntVal(IV);
817 B.generateNode(OOE, Pred,
818 Pred->getState()->BindExpr(OOE, Pred->getLocationContext(),
821 // FIXME: Handle the case where __builtin_offsetof is not a constant.
826 VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *Ex,
828 ExplodedNodeSet &Dst) {
829 // FIXME: Prechecks eventually go in ::Visit().
830 ExplodedNodeSet CheckedSet;
831 getCheckerManager().runCheckersForPreStmt(CheckedSet, Pred, Ex, *this);
833 ExplodedNodeSet EvalSet;
834 StmtNodeBuilder Bldr(CheckedSet, EvalSet, *currBldrCtx);
836 QualType T = Ex->getTypeOfArgument();
838 for (ExplodedNodeSet::iterator I = CheckedSet.begin(), E = CheckedSet.end();
840 if (Ex->getKind() == UETT_SizeOf) {
841 if (!T->isIncompleteType() && !T->isConstantSizeType()) {
842 assert(T->isVariableArrayType() && "Unknown non-constant-sized type.");
844 // FIXME: Add support for VLA type arguments and VLA expressions.
845 // When that happens, we should probably refactor VLASizeChecker's code.
847 } else if (T->getAs<ObjCObjectType>()) {
848 // Some code tries to take the sizeof an ObjCObjectType, relying that
849 // the compiler has laid out its representation. Just report Unknown
855 APSInt Value = Ex->EvaluateKnownConstInt(getContext());
856 CharUnits amt = CharUnits::fromQuantity(Value.getZExtValue());
858 ProgramStateRef state = (*I)->getState();
859 state = state->BindExpr(Ex, (*I)->getLocationContext(),
860 svalBuilder.makeIntVal(amt.getQuantity(),
862 Bldr.generateNode(Ex, *I, state);
865 getCheckerManager().runCheckersForPostStmt(Dst, EvalSet, Ex, *this);
868 void ExprEngine::handleUOExtension(ExplodedNodeSet::iterator I,
869 const UnaryOperator *U,
870 StmtNodeBuilder &Bldr) {
871 // FIXME: We can probably just have some magic in Environment::getSVal()
872 // that propagates values, instead of creating a new node here.
874 // Unary "+" is a no-op, similar to a parentheses. We still have places
875 // where it may be a block-level expression, so we need to
876 // generate an extra node that just propagates the value of the
878 const Expr *Ex = U->getSubExpr()->IgnoreParens();
879 ProgramStateRef state = (*I)->getState();
880 const LocationContext *LCtx = (*I)->getLocationContext();
881 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx,
882 state->getSVal(Ex, LCtx)));
885 void ExprEngine::VisitUnaryOperator(const UnaryOperator* U, ExplodedNode *Pred,
886 ExplodedNodeSet &Dst) {
887 // FIXME: Prechecks eventually go in ::Visit().
888 ExplodedNodeSet CheckedSet;
889 getCheckerManager().runCheckersForPreStmt(CheckedSet, Pred, U, *this);
891 ExplodedNodeSet EvalSet;
892 StmtNodeBuilder Bldr(CheckedSet, EvalSet, *currBldrCtx);
894 for (ExplodedNodeSet::iterator I = CheckedSet.begin(), E = CheckedSet.end();
896 switch (U->getOpcode()) {
900 VisitIncrementDecrementOperator(U, *I, Tmp);
905 const Expr *Ex = U->getSubExpr()->IgnoreParens();
907 // FIXME: We don't have complex SValues yet.
908 if (Ex->getType()->isAnyComplexType()) {
909 // Just report "Unknown."
913 // For all other types, UO_Real is an identity operation.
914 assert (U->getType() == Ex->getType());
915 ProgramStateRef state = (*I)->getState();
916 const LocationContext *LCtx = (*I)->getLocationContext();
917 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx,
918 state->getSVal(Ex, LCtx)));
923 const Expr *Ex = U->getSubExpr()->IgnoreParens();
924 // FIXME: We don't have complex SValues yet.
925 if (Ex->getType()->isAnyComplexType()) {
926 // Just report "Unknown."
929 // For all other types, UO_Imag returns 0.
930 ProgramStateRef state = (*I)->getState();
931 const LocationContext *LCtx = (*I)->getLocationContext();
932 SVal X = svalBuilder.makeZeroVal(Ex->getType());
933 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, X));
938 // Process pointer-to-member address operation.
939 const Expr *Ex = U->getSubExpr()->IgnoreParens();
940 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Ex)) {
941 const ValueDecl *VD = DRE->getDecl();
943 if (isa<CXXMethodDecl>(VD) || isa<FieldDecl>(VD)) {
944 ProgramStateRef State = (*I)->getState();
945 const LocationContext *LCtx = (*I)->getLocationContext();
946 SVal SV = svalBuilder.getMemberPointer(cast<DeclaratorDecl>(VD));
947 Bldr.generateNode(U, *I, State->BindExpr(U, LCtx, SV));
951 // Explicitly proceed with default handler for this case cascade.
952 handleUOExtension(I, U, Bldr);
956 assert(!U->isGLValue());
960 handleUOExtension(I, U, Bldr);
967 assert (!U->isGLValue());
968 const Expr *Ex = U->getSubExpr()->IgnoreParens();
969 ProgramStateRef state = (*I)->getState();
970 const LocationContext *LCtx = (*I)->getLocationContext();
972 // Get the value of the subexpression.
973 SVal V = state->getSVal(Ex, LCtx);
975 if (V.isUnknownOrUndef()) {
976 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, V));
980 switch (U->getOpcode()) {
982 llvm_unreachable("Invalid Opcode.");
984 // FIXME: Do we need to handle promotions?
985 state = state->BindExpr(U, LCtx, evalComplement(V.castAs<NonLoc>()));
988 // FIXME: Do we need to handle promotions?
989 state = state->BindExpr(U, LCtx, evalMinus(V.castAs<NonLoc>()));
992 // C99 6.5.3.3: "The expression !E is equivalent to (0==E)."
994 // Note: technically we do "E == 0", but this is the same in the
995 // transfer functions as "0 == E".
997 if (Optional<Loc> LV = V.getAs<Loc>()) {
998 Loc X = svalBuilder.makeNullWithType(Ex->getType());
999 Result = evalBinOp(state, BO_EQ, *LV, X, U->getType());
1000 } else if (Ex->getType()->isFloatingType()) {
1001 // FIXME: handle floating point types.
1002 Result = UnknownVal();
1004 nonloc::ConcreteInt X(getBasicVals().getValue(0, Ex->getType()));
1005 Result = evalBinOp(state, BO_EQ, V.castAs<NonLoc>(), X,
1009 state = state->BindExpr(U, LCtx, Result);
1012 Bldr.generateNode(U, *I, state);
1018 getCheckerManager().runCheckersForPostStmt(Dst, EvalSet, U, *this);
1021 void ExprEngine::VisitIncrementDecrementOperator(const UnaryOperator* U,
1023 ExplodedNodeSet &Dst) {
1024 // Handle ++ and -- (both pre- and post-increment).
1025 assert (U->isIncrementDecrementOp());
1026 const Expr *Ex = U->getSubExpr()->IgnoreParens();
1028 const LocationContext *LCtx = Pred->getLocationContext();
1029 ProgramStateRef state = Pred->getState();
1030 SVal loc = state->getSVal(Ex, LCtx);
1033 ExplodedNodeSet Tmp;
1034 evalLoad(Tmp, U, Ex, Pred, state, loc);
1036 ExplodedNodeSet Dst2;
1037 StmtNodeBuilder Bldr(Tmp, Dst2, *currBldrCtx);
1038 for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end();I!=E;++I) {
1040 state = (*I)->getState();
1041 assert(LCtx == (*I)->getLocationContext());
1042 SVal V2_untested = state->getSVal(Ex, LCtx);
1044 // Propagate unknown and undefined values.
1045 if (V2_untested.isUnknownOrUndef()) {
1046 state = state->BindExpr(U, LCtx, V2_untested);
1048 // Perform the store, so that the uninitialized value detection happens.
1050 ExplodedNodeSet Dst3;
1051 evalStore(Dst3, U, U, *I, state, loc, V2_untested);
1052 Bldr.addNodes(Dst3);
1056 DefinedSVal V2 = V2_untested.castAs<DefinedSVal>();
1058 // Handle all other values.
1059 BinaryOperator::Opcode Op = U->isIncrementOp() ? BO_Add : BO_Sub;
1061 // If the UnaryOperator has non-location type, use its type to create the
1062 // constant value. If the UnaryOperator has location type, create the
1063 // constant with int type and pointer width.
1066 if (U->getType()->isAnyPointerType())
1067 RHS = svalBuilder.makeArrayIndex(1);
1068 else if (U->getType()->isIntegralOrEnumerationType())
1069 RHS = svalBuilder.makeIntVal(1, U->getType());
1073 SVal Result = evalBinOp(state, Op, V2, RHS, U->getType());
1075 // Conjure a new symbol if necessary to recover precision.
1076 if (Result.isUnknown()){
1077 DefinedOrUnknownSVal SymVal =
1078 svalBuilder.conjureSymbolVal(nullptr, U, LCtx,
1079 currBldrCtx->blockCount());
1082 // If the value is a location, ++/-- should always preserve
1083 // non-nullness. Check if the original value was non-null, and if so
1084 // propagate that constraint.
1085 if (Loc::isLocType(U->getType())) {
1086 DefinedOrUnknownSVal Constraint =
1087 svalBuilder.evalEQ(state, V2,svalBuilder.makeZeroVal(U->getType()));
1089 if (!state->assume(Constraint, true)) {
1090 // It isn't feasible for the original value to be null.
1091 // Propagate this constraint.
1092 Constraint = svalBuilder.evalEQ(state, SymVal,
1093 svalBuilder.makeZeroVal(U->getType()));
1096 state = state->assume(Constraint, false);
1102 // Since the lvalue-to-rvalue conversion is explicit in the AST,
1103 // we bind an l-value if the operator is prefix and an lvalue (in C++).
1105 state = state->BindExpr(U, LCtx, loc);
1107 state = state->BindExpr(U, LCtx, U->isPostfix() ? V2 : Result);
1109 // Perform the store.
1111 ExplodedNodeSet Dst3;
1112 evalStore(Dst3, U, U, *I, state, loc, Result);
1113 Bldr.addNodes(Dst3);