Bug Summary

File:clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp
Warning:line 822, column 24
Forming reference to null pointer

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name ExprEngineC.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -relaxed-aliasing -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/tools/clang/lib/StaticAnalyzer/Core -resource-dir /usr/lib/llvm-14/lib/clang/14.0.0 -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/tools/clang/lib/StaticAnalyzer/Core -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/clang/lib/StaticAnalyzer/Core -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/clang/include -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/tools/clang/include -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/include -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/include -D NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-14/lib/clang/14.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/tools/clang/lib/StaticAnalyzer/Core -fdebug-prefix-map=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e=. -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2021-09-04-040900-46481-1 -x c++ /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp
1//=-- ExprEngineC.cpp - ExprEngine support for C expressions ----*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file defines ExprEngine's support for C expressions.
10//
11//===----------------------------------------------------------------------===//
12
13#include "clang/AST/ExprCXX.h"
14#include "clang/AST/DeclCXX.h"
15#include "clang/StaticAnalyzer/Core/CheckerManager.h"
16#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
17
18using namespace clang;
19using namespace ento;
20using llvm::APSInt;
21
22/// Optionally conjure and return a symbol for offset when processing
23/// an expression \p Expression.
24/// If \p Other is a location, conjure a symbol for \p Symbol
25/// (offset) if it is unknown so that memory arithmetic always
26/// results in an ElementRegion.
27/// \p Count The number of times the current basic block was visited.
28static SVal conjureOffsetSymbolOnLocation(
29 SVal Symbol, SVal Other, Expr* Expression, SValBuilder &svalBuilder,
30 unsigned Count, const LocationContext *LCtx) {
31 QualType Ty = Expression->getType();
32 if (Other.getAs<Loc>() &&
33 Ty->isIntegralOrEnumerationType() &&
34 Symbol.isUnknown()) {
35 return svalBuilder.conjureSymbolVal(Expression, LCtx, Ty, Count);
36 }
37 return Symbol;
38}
39
40void ExprEngine::VisitBinaryOperator(const BinaryOperator* B,
41 ExplodedNode *Pred,
42 ExplodedNodeSet &Dst) {
43
44 Expr *LHS = B->getLHS()->IgnoreParens();
45 Expr *RHS = B->getRHS()->IgnoreParens();
46
47 // FIXME: Prechecks eventually go in ::Visit().
48 ExplodedNodeSet CheckedSet;
49 ExplodedNodeSet Tmp2;
50 getCheckerManager().runCheckersForPreStmt(CheckedSet, Pred, B, *this);
51
52 // With both the LHS and RHS evaluated, process the operation itself.
53 for (ExplodedNodeSet::iterator it=CheckedSet.begin(), ei=CheckedSet.end();
54 it != ei; ++it) {
55
56 ProgramStateRef state = (*it)->getState();
57 const LocationContext *LCtx = (*it)->getLocationContext();
58 SVal LeftV = state->getSVal(LHS, LCtx);
59 SVal RightV = state->getSVal(RHS, LCtx);
60
61 BinaryOperator::Opcode Op = B->getOpcode();
62
63 if (Op == BO_Assign) {
64 // EXPERIMENTAL: "Conjured" symbols.
65 // FIXME: Handle structs.
66 if (RightV.isUnknown()) {
67 unsigned Count = currBldrCtx->blockCount();
68 RightV = svalBuilder.conjureSymbolVal(nullptr, B->getRHS(), LCtx,
69 Count);
70 }
71 // Simulate the effects of a "store": bind the value of the RHS
72 // to the L-Value represented by the LHS.
73 SVal ExprVal = B->isGLValue() ? LeftV : RightV;
74 evalStore(Tmp2, B, LHS, *it, state->BindExpr(B, LCtx, ExprVal),
75 LeftV, RightV);
76 continue;
77 }
78
79 if (!B->isAssignmentOp()) {
80 StmtNodeBuilder Bldr(*it, Tmp2, *currBldrCtx);
81
82 if (B->isAdditiveOp()) {
83 // TODO: This can be removed after we enable history tracking with
84 // SymSymExpr.
85 unsigned Count = currBldrCtx->blockCount();
86 RightV = conjureOffsetSymbolOnLocation(
87 RightV, LeftV, RHS, svalBuilder, Count, LCtx);
88 LeftV = conjureOffsetSymbolOnLocation(
89 LeftV, RightV, LHS, svalBuilder, Count, LCtx);
90 }
91
92 // Although we don't yet model pointers-to-members, we do need to make
93 // sure that the members of temporaries have a valid 'this' pointer for
94 // other checks.
95 if (B->getOpcode() == BO_PtrMemD)
96 state = createTemporaryRegionIfNeeded(state, LCtx, LHS);
97
98 // Process non-assignments except commas or short-circuited
99 // logical expressions (LAnd and LOr).
100 SVal Result = evalBinOp(state, Op, LeftV, RightV, B->getType());
101 if (!Result.isUnknown()) {
102 state = state->BindExpr(B, LCtx, Result);
103 } else {
104 // If we cannot evaluate the operation escape the operands.
105 state = escapeValues(state, LeftV, PSK_EscapeOther);
106 state = escapeValues(state, RightV, PSK_EscapeOther);
107 }
108
109 Bldr.generateNode(B, *it, state);
110 continue;
111 }
112
113 assert (B->isCompoundAssignmentOp())(static_cast<void> (0));
114
115 switch (Op) {
116 default:
117 llvm_unreachable("Invalid opcode for compound assignment.")__builtin_unreachable();
118 case BO_MulAssign: Op = BO_Mul; break;
119 case BO_DivAssign: Op = BO_Div; break;
120 case BO_RemAssign: Op = BO_Rem; break;
121 case BO_AddAssign: Op = BO_Add; break;
122 case BO_SubAssign: Op = BO_Sub; break;
123 case BO_ShlAssign: Op = BO_Shl; break;
124 case BO_ShrAssign: Op = BO_Shr; break;
125 case BO_AndAssign: Op = BO_And; break;
126 case BO_XorAssign: Op = BO_Xor; break;
127 case BO_OrAssign: Op = BO_Or; break;
128 }
129
130 // Perform a load (the LHS). This performs the checks for
131 // null dereferences, and so on.
132 ExplodedNodeSet Tmp;
133 SVal location = LeftV;
134 evalLoad(Tmp, B, LHS, *it, state, location);
135
136 for (ExplodedNodeSet::iterator I = Tmp.begin(), E = Tmp.end(); I != E;
137 ++I) {
138
139 state = (*I)->getState();
140 const LocationContext *LCtx = (*I)->getLocationContext();
141 SVal V = state->getSVal(LHS, LCtx);
142
143 // Get the computation type.
144 QualType CTy =
145 cast<CompoundAssignOperator>(B)->getComputationResultType();
146 CTy = getContext().getCanonicalType(CTy);
147
148 QualType CLHSTy =
149 cast<CompoundAssignOperator>(B)->getComputationLHSType();
150 CLHSTy = getContext().getCanonicalType(CLHSTy);
151
152 QualType LTy = getContext().getCanonicalType(LHS->getType());
153
154 // Promote LHS.
155 V = svalBuilder.evalCast(V, CLHSTy, LTy);
156
157 // Compute the result of the operation.
158 SVal Result = svalBuilder.evalCast(evalBinOp(state, Op, V, RightV, CTy),
159 B->getType(), CTy);
160
161 // EXPERIMENTAL: "Conjured" symbols.
162 // FIXME: Handle structs.
163
164 SVal LHSVal;
165
166 if (Result.isUnknown()) {
167 // The symbolic value is actually for the type of the left-hand side
168 // expression, not the computation type, as this is the value the
169 // LValue on the LHS will bind to.
170 LHSVal = svalBuilder.conjureSymbolVal(nullptr, B->getRHS(), LCtx, LTy,
171 currBldrCtx->blockCount());
172 // However, we need to convert the symbol to the computation type.
173 Result = svalBuilder.evalCast(LHSVal, CTy, LTy);
174 }
175 else {
176 // The left-hand side may bind to a different value then the
177 // computation type.
178 LHSVal = svalBuilder.evalCast(Result, LTy, CTy);
179 }
180
181 // In C++, assignment and compound assignment operators return an
182 // lvalue.
183 if (B->isGLValue())
184 state = state->BindExpr(B, LCtx, location);
185 else
186 state = state->BindExpr(B, LCtx, Result);
187
188 evalStore(Tmp2, B, LHS, *I, state, location, LHSVal);
189 }
190 }
191
192 // FIXME: postvisits eventually go in ::Visit()
193 getCheckerManager().runCheckersForPostStmt(Dst, Tmp2, B, *this);
194}
195
196void ExprEngine::VisitBlockExpr(const BlockExpr *BE, ExplodedNode *Pred,
197 ExplodedNodeSet &Dst) {
198
199 CanQualType T = getContext().getCanonicalType(BE->getType());
200
201 const BlockDecl *BD = BE->getBlockDecl();
202 // Get the value of the block itself.
203 SVal V = svalBuilder.getBlockPointer(BD, T,
204 Pred->getLocationContext(),
205 currBldrCtx->blockCount());
206
207 ProgramStateRef State = Pred->getState();
208
209 // If we created a new MemRegion for the block, we should explicitly bind
210 // the captured variables.
211 if (const BlockDataRegion *BDR =
212 dyn_cast_or_null<BlockDataRegion>(V.getAsRegion())) {
213
214 BlockDataRegion::referenced_vars_iterator I = BDR->referenced_vars_begin(),
215 E = BDR->referenced_vars_end();
216
217 auto CI = BD->capture_begin();
218 auto CE = BD->capture_end();
219 for (; I != E; ++I) {
220 const VarRegion *capturedR = I.getCapturedRegion();
221 const TypedValueRegion *originalR = I.getOriginalRegion();
222
223 // If the capture had a copy expression, use the result of evaluating
224 // that expression, otherwise use the original value.
225 // We rely on the invariant that the block declaration's capture variables
226 // are a prefix of the BlockDataRegion's referenced vars (which may include
227 // referenced globals, etc.) to enable fast lookup of the capture for a
228 // given referenced var.
229 const Expr *copyExpr = nullptr;
230 if (CI != CE) {
231 assert(CI->getVariable() == capturedR->getDecl())(static_cast<void> (0));
232 copyExpr = CI->getCopyExpr();
233 CI++;
234 }
235
236 if (capturedR != originalR) {
237 SVal originalV;
238 const LocationContext *LCtx = Pred->getLocationContext();
239 if (copyExpr) {
240 originalV = State->getSVal(copyExpr, LCtx);
241 } else {
242 originalV = State->getSVal(loc::MemRegionVal(originalR));
243 }
244 State = State->bindLoc(loc::MemRegionVal(capturedR), originalV, LCtx);
245 }
246 }
247 }
248
249 ExplodedNodeSet Tmp;
250 StmtNodeBuilder Bldr(Pred, Tmp, *currBldrCtx);
251 Bldr.generateNode(BE, Pred,
252 State->BindExpr(BE, Pred->getLocationContext(), V),
253 nullptr, ProgramPoint::PostLValueKind);
254
255 // FIXME: Move all post/pre visits to ::Visit().
256 getCheckerManager().runCheckersForPostStmt(Dst, Tmp, BE, *this);
257}
258
259ProgramStateRef ExprEngine::handleLValueBitCast(
260 ProgramStateRef state, const Expr* Ex, const LocationContext* LCtx,
261 QualType T, QualType ExTy, const CastExpr* CastE, StmtNodeBuilder& Bldr,
262 ExplodedNode* Pred) {
263 if (T->isLValueReferenceType()) {
264 assert(!CastE->getType()->isLValueReferenceType())(static_cast<void> (0));
265 ExTy = getContext().getLValueReferenceType(ExTy);
266 } else if (T->isRValueReferenceType()) {
267 assert(!CastE->getType()->isRValueReferenceType())(static_cast<void> (0));
268 ExTy = getContext().getRValueReferenceType(ExTy);
269 }
270 // Delegate to SValBuilder to process.
271 SVal OrigV = state->getSVal(Ex, LCtx);
272 SVal V = svalBuilder.evalCast(OrigV, T, ExTy);
273 // Negate the result if we're treating the boolean as a signed i1
274 if (CastE->getCastKind() == CK_BooleanToSignedIntegral)
275 V = evalMinus(V);
276 state = state->BindExpr(CastE, LCtx, V);
277 if (V.isUnknown() && !OrigV.isUnknown()) {
278 state = escapeValues(state, OrigV, PSK_EscapeOther);
279 }
280 Bldr.generateNode(CastE, Pred, state);
281
282 return state;
283}
284
285void ExprEngine::VisitCast(const CastExpr *CastE, const Expr *Ex,
286 ExplodedNode *Pred, ExplodedNodeSet &Dst) {
287
288 ExplodedNodeSet dstPreStmt;
289 getCheckerManager().runCheckersForPreStmt(dstPreStmt, Pred, CastE, *this);
290
291 if (CastE->getCastKind() == CK_LValueToRValue ||
292 CastE->getCastKind() == CK_LValueToRValueBitCast) {
293 for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end();
294 I!=E; ++I) {
295 ExplodedNode *subExprNode = *I;
296 ProgramStateRef state = subExprNode->getState();
297 const LocationContext *LCtx = subExprNode->getLocationContext();
298 evalLoad(Dst, CastE, CastE, subExprNode, state, state->getSVal(Ex, LCtx));
299 }
300 return;
301 }
302
303 // All other casts.
304 QualType T = CastE->getType();
305 QualType ExTy = Ex->getType();
306
307 if (const ExplicitCastExpr *ExCast=dyn_cast_or_null<ExplicitCastExpr>(CastE))
308 T = ExCast->getTypeAsWritten();
309
310 StmtNodeBuilder Bldr(dstPreStmt, Dst, *currBldrCtx);
311 for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end();
312 I != E; ++I) {
313
314 Pred = *I;
315 ProgramStateRef state = Pred->getState();
316 const LocationContext *LCtx = Pred->getLocationContext();
317
318 switch (CastE->getCastKind()) {
319 case CK_LValueToRValue:
320 case CK_LValueToRValueBitCast:
321 llvm_unreachable("LValueToRValue casts handled earlier.")__builtin_unreachable();
322 case CK_ToVoid:
323 continue;
324 // The analyzer doesn't do anything special with these casts,
325 // since it understands retain/release semantics already.
326 case CK_ARCProduceObject:
327 case CK_ARCConsumeObject:
328 case CK_ARCReclaimReturnedObject:
329 case CK_ARCExtendBlockObject: // Fall-through.
330 case CK_CopyAndAutoreleaseBlockObject:
331 // The analyser can ignore atomic casts for now, although some future
332 // checkers may want to make certain that you're not modifying the same
333 // value through atomic and nonatomic pointers.
334 case CK_AtomicToNonAtomic:
335 case CK_NonAtomicToAtomic:
336 // True no-ops.
337 case CK_NoOp:
338 case CK_ConstructorConversion:
339 case CK_UserDefinedConversion:
340 case CK_FunctionToPointerDecay:
341 case CK_BuiltinFnToFnPtr: {
342 // Copy the SVal of Ex to CastE.
343 ProgramStateRef state = Pred->getState();
344 const LocationContext *LCtx = Pred->getLocationContext();
345 SVal V = state->getSVal(Ex, LCtx);
346 state = state->BindExpr(CastE, LCtx, V);
347 Bldr.generateNode(CastE, Pred, state);
348 continue;
349 }
350 case CK_MemberPointerToBoolean:
351 case CK_PointerToBoolean: {
352 SVal V = state->getSVal(Ex, LCtx);
353 auto PTMSV = V.getAs<nonloc::PointerToMember>();
354 if (PTMSV)
355 V = svalBuilder.makeTruthVal(!PTMSV->isNullMemberPointer(), ExTy);
356 if (V.isUndef() || PTMSV) {
357 state = state->BindExpr(CastE, LCtx, V);
358 Bldr.generateNode(CastE, Pred, state);
359 continue;
360 }
361 // Explicitly proceed with default handler for this case cascade.
362 state =
363 handleLValueBitCast(state, Ex, LCtx, T, ExTy, CastE, Bldr, Pred);
364 continue;
365 }
366 case CK_Dependent:
367 case CK_ArrayToPointerDecay:
368 case CK_BitCast:
369 case CK_AddressSpaceConversion:
370 case CK_BooleanToSignedIntegral:
371 case CK_IntegralToPointer:
372 case CK_PointerToIntegral: {
373 SVal V = state->getSVal(Ex, LCtx);
374 if (V.getAs<nonloc::PointerToMember>()) {
375 state = state->BindExpr(CastE, LCtx, UnknownVal());
376 Bldr.generateNode(CastE, Pred, state);
377 continue;
378 }
379 // Explicitly proceed with default handler for this case cascade.
380 state =
381 handleLValueBitCast(state, Ex, LCtx, T, ExTy, CastE, Bldr, Pred);
382 continue;
383 }
384 case CK_IntegralToBoolean:
385 case CK_IntegralToFloating:
386 case CK_FloatingToIntegral:
387 case CK_FloatingToBoolean:
388 case CK_FloatingCast:
389 case CK_FloatingRealToComplex:
390 case CK_FloatingComplexToReal:
391 case CK_FloatingComplexToBoolean:
392 case CK_FloatingComplexCast:
393 case CK_FloatingComplexToIntegralComplex:
394 case CK_IntegralRealToComplex:
395 case CK_IntegralComplexToReal:
396 case CK_IntegralComplexToBoolean:
397 case CK_IntegralComplexCast:
398 case CK_IntegralComplexToFloatingComplex:
399 case CK_CPointerToObjCPointerCast:
400 case CK_BlockPointerToObjCPointerCast:
401 case CK_AnyPointerToBlockPointerCast:
402 case CK_ObjCObjectLValueCast:
403 case CK_ZeroToOCLOpaqueType:
404 case CK_IntToOCLSampler:
405 case CK_LValueBitCast:
406 case CK_FloatingToFixedPoint:
407 case CK_FixedPointToFloating:
408 case CK_FixedPointCast:
409 case CK_FixedPointToBoolean:
410 case CK_FixedPointToIntegral:
411 case CK_IntegralToFixedPoint: {
412 state =
413 handleLValueBitCast(state, Ex, LCtx, T, ExTy, CastE, Bldr, Pred);
414 continue;
415 }
416 case CK_IntegralCast: {
417 // Delegate to SValBuilder to process.
418 SVal V = state->getSVal(Ex, LCtx);
419 V = svalBuilder.evalIntegralCast(state, V, T, ExTy);
420 state = state->BindExpr(CastE, LCtx, V);
421 Bldr.generateNode(CastE, Pred, state);
422 continue;
423 }
424 case CK_DerivedToBase:
425 case CK_UncheckedDerivedToBase: {
426 // For DerivedToBase cast, delegate to the store manager.
427 SVal val = state->getSVal(Ex, LCtx);
428 val = getStoreManager().evalDerivedToBase(val, CastE);
429 state = state->BindExpr(CastE, LCtx, val);
430 Bldr.generateNode(CastE, Pred, state);
431 continue;
432 }
433 // Handle C++ dyn_cast.
434 case CK_Dynamic: {
435 SVal val = state->getSVal(Ex, LCtx);
436
437 // Compute the type of the result.
438 QualType resultType = CastE->getType();
439 if (CastE->isGLValue())
440 resultType = getContext().getPointerType(resultType);
441
442 bool Failed = false;
443
444 // Check if the value being cast evaluates to 0.
445 if (val.isZeroConstant())
446 Failed = true;
447 // Else, evaluate the cast.
448 else
449 val = getStoreManager().attemptDownCast(val, T, Failed);
450
451 if (Failed) {
452 if (T->isReferenceType()) {
453 // A bad_cast exception is thrown if input value is a reference.
454 // Currently, we model this, by generating a sink.
455 Bldr.generateSink(CastE, Pred, state);
456 continue;
457 } else {
458 // If the cast fails on a pointer, bind to 0.
459 state = state->BindExpr(CastE, LCtx, svalBuilder.makeNull());
460 }
461 } else {
462 // If we don't know if the cast succeeded, conjure a new symbol.
463 if (val.isUnknown()) {
464 DefinedOrUnknownSVal NewSym =
465 svalBuilder.conjureSymbolVal(nullptr, CastE, LCtx, resultType,
466 currBldrCtx->blockCount());
467 state = state->BindExpr(CastE, LCtx, NewSym);
468 } else
469 // Else, bind to the derived region value.
470 state = state->BindExpr(CastE, LCtx, val);
471 }
472 Bldr.generateNode(CastE, Pred, state);
473 continue;
474 }
475 case CK_BaseToDerived: {
476 SVal val = state->getSVal(Ex, LCtx);
477 QualType resultType = CastE->getType();
478 if (CastE->isGLValue())
479 resultType = getContext().getPointerType(resultType);
480
481 bool Failed = false;
482
483 if (!val.isConstant()) {
484 val = getStoreManager().attemptDownCast(val, T, Failed);
485 }
486
487 // Failed to cast or the result is unknown, fall back to conservative.
488 if (Failed || val.isUnknown()) {
489 val =
490 svalBuilder.conjureSymbolVal(nullptr, CastE, LCtx, resultType,
491 currBldrCtx->blockCount());
492 }
493 state = state->BindExpr(CastE, LCtx, val);
494 Bldr.generateNode(CastE, Pred, state);
495 continue;
496 }
497 case CK_NullToPointer: {
498 SVal V = svalBuilder.makeNull();
499 state = state->BindExpr(CastE, LCtx, V);
500 Bldr.generateNode(CastE, Pred, state);
501 continue;
502 }
503 case CK_NullToMemberPointer: {
504 SVal V = svalBuilder.getMemberPointer(nullptr);
505 state = state->BindExpr(CastE, LCtx, V);
506 Bldr.generateNode(CastE, Pred, state);
507 continue;
508 }
509 case CK_DerivedToBaseMemberPointer:
510 case CK_BaseToDerivedMemberPointer:
511 case CK_ReinterpretMemberPointer: {
512 SVal V = state->getSVal(Ex, LCtx);
513 if (auto PTMSV = V.getAs<nonloc::PointerToMember>()) {
514 SVal CastedPTMSV =
515 svalBuilder.makePointerToMember(getBasicVals().accumCXXBase(
516 CastE->path(), *PTMSV, CastE->getCastKind()));
517 state = state->BindExpr(CastE, LCtx, CastedPTMSV);
518 Bldr.generateNode(CastE, Pred, state);
519 continue;
520 }
521 // Explicitly proceed with default handler for this case cascade.
522 }
523 LLVM_FALLTHROUGH[[gnu::fallthrough]];
524 // Various C++ casts that are not handled yet.
525 case CK_ToUnion:
526 case CK_MatrixCast:
527 case CK_VectorSplat: {
528 QualType resultType = CastE->getType();
529 if (CastE->isGLValue())
530 resultType = getContext().getPointerType(resultType);
531 SVal result = svalBuilder.conjureSymbolVal(
532 /*symbolTag=*/nullptr, CastE, LCtx, resultType,
533 currBldrCtx->blockCount());
534 state = state->BindExpr(CastE, LCtx, result);
535 Bldr.generateNode(CastE, Pred, state);
536 continue;
537 }
538 }
539 }
540}
541
542void ExprEngine::VisitCompoundLiteralExpr(const CompoundLiteralExpr *CL,
543 ExplodedNode *Pred,
544 ExplodedNodeSet &Dst) {
545 StmtNodeBuilder B(Pred, Dst, *currBldrCtx);
546
547 ProgramStateRef State = Pred->getState();
548 const LocationContext *LCtx = Pred->getLocationContext();
549
550 const Expr *Init = CL->getInitializer();
551 SVal V = State->getSVal(CL->getInitializer(), LCtx);
552
553 if (isa<CXXConstructExpr>(Init) || isa<CXXStdInitializerListExpr>(Init)) {
554 // No work needed. Just pass the value up to this expression.
555 } else {
556 assert(isa<InitListExpr>(Init))(static_cast<void> (0));
557 Loc CLLoc = State->getLValue(CL, LCtx);
558 State = State->bindLoc(CLLoc, V, LCtx);
559
560 if (CL->isGLValue())
561 V = CLLoc;
562 }
563
564 B.generateNode(CL, Pred, State->BindExpr(CL, LCtx, V));
565}
566
567void ExprEngine::VisitDeclStmt(const DeclStmt *DS, ExplodedNode *Pred,
568 ExplodedNodeSet &Dst) {
569 if (isa<TypedefNameDecl>(*DS->decl_begin())) {
570 // C99 6.7.7 "Any array size expressions associated with variable length
571 // array declarators are evaluated each time the declaration of the typedef
572 // name is reached in the order of execution."
573 // The checkers should know about typedef to be able to handle VLA size
574 // expressions.
575 ExplodedNodeSet DstPre;
576 getCheckerManager().runCheckersForPreStmt(DstPre, Pred, DS, *this);
577 getCheckerManager().runCheckersForPostStmt(Dst, DstPre, DS, *this);
578 return;
579 }
580
581 // Assumption: The CFG has one DeclStmt per Decl.
582 const VarDecl *VD = dyn_cast_or_null<VarDecl>(*DS->decl_begin());
583
584 if (!VD) {
585 //TODO:AZ: remove explicit insertion after refactoring is done.
586 Dst.insert(Pred);
587 return;
588 }
589
590 // FIXME: all pre/post visits should eventually be handled by ::Visit().
591 ExplodedNodeSet dstPreVisit;
592 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, DS, *this);
593
594 ExplodedNodeSet dstEvaluated;
595 StmtNodeBuilder B(dstPreVisit, dstEvaluated, *currBldrCtx);
596 for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end();
597 I!=E; ++I) {
598 ExplodedNode *N = *I;
599 ProgramStateRef state = N->getState();
600 const LocationContext *LC = N->getLocationContext();
601
602 // Decls without InitExpr are not initialized explicitly.
603 if (const Expr *InitEx = VD->getInit()) {
604
605 // Note in the state that the initialization has occurred.
606 ExplodedNode *UpdatedN = N;
607 SVal InitVal = state->getSVal(InitEx, LC);
608
609 assert(DS->isSingleDecl())(static_cast<void> (0));
610 if (getObjectUnderConstruction(state, DS, LC)) {
611 state = finishObjectConstruction(state, DS, LC);
612 // We constructed the object directly in the variable.
613 // No need to bind anything.
614 B.generateNode(DS, UpdatedN, state);
615 } else {
616 // Recover some path-sensitivity if a scalar value evaluated to
617 // UnknownVal.
618 if (InitVal.isUnknown()) {
619 QualType Ty = InitEx->getType();
620 if (InitEx->isGLValue()) {
621 Ty = getContext().getPointerType(Ty);
622 }
623
624 InitVal = svalBuilder.conjureSymbolVal(nullptr, InitEx, LC, Ty,
625 currBldrCtx->blockCount());
626 }
627
628
629 B.takeNodes(UpdatedN);
630 ExplodedNodeSet Dst2;
631 evalBind(Dst2, DS, UpdatedN, state->getLValue(VD, LC), InitVal, true);
632 B.addNodes(Dst2);
633 }
634 }
635 else {
636 B.generateNode(DS, N, state);
637 }
638 }
639
640 getCheckerManager().runCheckersForPostStmt(Dst, B.getResults(), DS, *this);
641}
642
643void ExprEngine::VisitLogicalExpr(const BinaryOperator* B, ExplodedNode *Pred,
644 ExplodedNodeSet &Dst) {
645 // This method acts upon CFG elements for logical operators && and ||
646 // and attaches the value (true or false) to them as expressions.
647 // It doesn't produce any state splits.
648 // If we made it that far, we're past the point when we modeled the short
649 // circuit. It means that we should have precise knowledge about whether
650 // we've short-circuited. If we did, we already know the value we need to
651 // bind. If we didn't, the value of the RHS (casted to the boolean type)
652 // is the answer.
653 // Currently this method tries to figure out whether we've short-circuited
654 // by looking at the ExplodedGraph. This method is imperfect because there
655 // could inevitably have been merges that would have resulted in multiple
656 // potential path traversal histories. We bail out when we fail.
657 // Due to this ambiguity, a more reliable solution would have been to
658 // track the short circuit operation history path-sensitively until
659 // we evaluate the respective logical operator.
660 assert(B->getOpcode() == BO_LAnd ||(static_cast<void> (0))
661 B->getOpcode() == BO_LOr)(static_cast<void> (0));
662
663 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx);
664 ProgramStateRef state = Pred->getState();
665
666 if (B->getType()->isVectorType()) {
667 // FIXME: We do not model vector arithmetic yet. When adding support for
668 // that, note that the CFG-based reasoning below does not apply, because
669 // logical operators on vectors are not short-circuit. Currently they are
670 // modeled as short-circuit in Clang CFG but this is incorrect.
671 // Do not set the value for the expression. It'd be UnknownVal by default.
672 Bldr.generateNode(B, Pred, state);
673 return;
674 }
675
676 ExplodedNode *N = Pred;
677 while (!N->getLocation().getAs<BlockEntrance>()) {
678 ProgramPoint P = N->getLocation();
679 assert(P.getAs<PreStmt>()|| P.getAs<PreStmtPurgeDeadSymbols>())(static_cast<void> (0));
680 (void) P;
681 if (N->pred_size() != 1) {
682 // We failed to track back where we came from.
683 Bldr.generateNode(B, Pred, state);
684 return;
685 }
686 N = *N->pred_begin();
687 }
688
689 if (N->pred_size() != 1) {
690 // We failed to track back where we came from.
691 Bldr.generateNode(B, Pred, state);
692 return;
693 }
694
695 N = *N->pred_begin();
696 BlockEdge BE = N->getLocation().castAs<BlockEdge>();
697 SVal X;
698
699 // Determine the value of the expression by introspecting how we
700 // got this location in the CFG. This requires looking at the previous
701 // block we were in and what kind of control-flow transfer was involved.
702 const CFGBlock *SrcBlock = BE.getSrc();
703 // The only terminator (if there is one) that makes sense is a logical op.
704 CFGTerminator T = SrcBlock->getTerminator();
705 if (const BinaryOperator *Term = cast_or_null<BinaryOperator>(T.getStmt())) {
706 (void) Term;
707 assert(Term->isLogicalOp())(static_cast<void> (0));
708 assert(SrcBlock->succ_size() == 2)(static_cast<void> (0));
709 // Did we take the true or false branch?
710 unsigned constant = (*SrcBlock->succ_begin() == BE.getDst()) ? 1 : 0;
711 X = svalBuilder.makeIntVal(constant, B->getType());
712 }
713 else {
714 // If there is no terminator, by construction the last statement
715 // in SrcBlock is the value of the enclosing expression.
716 // However, we still need to constrain that value to be 0 or 1.
717 assert(!SrcBlock->empty())(static_cast<void> (0));
718 CFGStmt Elem = SrcBlock->rbegin()->castAs<CFGStmt>();
719 const Expr *RHS = cast<Expr>(Elem.getStmt());
720 SVal RHSVal = N->getState()->getSVal(RHS, Pred->getLocationContext());
721
722 if (RHSVal.isUndef()) {
723 X = RHSVal;
724 } else {
725 // We evaluate "RHSVal != 0" expression which result in 0 if the value is
726 // known to be false, 1 if the value is known to be true and a new symbol
727 // when the assumption is unknown.
728 nonloc::ConcreteInt Zero(getBasicVals().getValue(0, B->getType()));
729 X = evalBinOp(N->getState(), BO_NE,
730 svalBuilder.evalCast(RHSVal, B->getType(), RHS->getType()),
731 Zero, B->getType());
732 }
733 }
734 Bldr.generateNode(B, Pred, state->BindExpr(B, Pred->getLocationContext(), X));
735}
736
737void ExprEngine::VisitInitListExpr(const InitListExpr *IE,
738 ExplodedNode *Pred,
739 ExplodedNodeSet &Dst) {
740 StmtNodeBuilder B(Pred, Dst, *currBldrCtx);
741
742 ProgramStateRef state = Pred->getState();
743 const LocationContext *LCtx = Pred->getLocationContext();
744 QualType T = getContext().getCanonicalType(IE->getType());
745 unsigned NumInitElements = IE->getNumInits();
746
747 if (!IE->isGLValue() && !IE->isTransparent() &&
748 (T->isArrayType() || T->isRecordType() || T->isVectorType() ||
749 T->isAnyComplexType())) {
750 llvm::ImmutableList<SVal> vals = getBasicVals().getEmptySValList();
751
752 // Handle base case where the initializer has no elements.
753 // e.g: static int* myArray[] = {};
754 if (NumInitElements == 0) {
755 SVal V = svalBuilder.makeCompoundVal(T, vals);
756 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V));
757 return;
758 }
759
760 for (InitListExpr::const_reverse_iterator it = IE->rbegin(),
761 ei = IE->rend(); it != ei; ++it) {
762 SVal V = state->getSVal(cast<Expr>(*it), LCtx);
763 vals = getBasicVals().prependSVal(V, vals);
764 }
765
766 B.generateNode(IE, Pred,
767 state->BindExpr(IE, LCtx,
768 svalBuilder.makeCompoundVal(T, vals)));
769 return;
770 }
771
772 // Handle scalars: int{5} and int{} and GLvalues.
773 // Note, if the InitListExpr is a GLvalue, it means that there is an address
774 // representing it, so it must have a single init element.
775 assert(NumInitElements <= 1)(static_cast<void> (0));
776
777 SVal V;
778 if (NumInitElements == 0)
779 V = getSValBuilder().makeZeroVal(T);
780 else
781 V = state->getSVal(IE->getInit(0), LCtx);
782
783 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V));
784}
785
786void ExprEngine::VisitGuardedExpr(const Expr *Ex,
787 const Expr *L,
788 const Expr *R,
789 ExplodedNode *Pred,
790 ExplodedNodeSet &Dst) {
791 assert(L && R)(static_cast<void> (0));
792
793 StmtNodeBuilder B(Pred, Dst, *currBldrCtx);
794 ProgramStateRef state = Pred->getState();
795 const LocationContext *LCtx = Pred->getLocationContext();
796 const CFGBlock *SrcBlock = nullptr;
1
'SrcBlock' initialized to a null pointer value
→
797
798 // Find the predecessor block.
799 ProgramStateRef SrcState = state;
800 for (const ExplodedNode *N = Pred ; N ; N = *N->pred_begin()) {
2
←
Loop condition is true. Entering loop body
→
6
←
Loop condition is false. Execution continues on line 815
→
801 ProgramPoint PP = N->getLocation();
802 if (PP.getAs<PreStmtPurgeDeadSymbols>() || PP.getAs<BlockEntrance>()) {
3
←
Assuming the condition is true
→
4
←
Taking true branch
→
803 // If the state N has multiple predecessors P, it means that successors
804 // of P are all equivalent.
805 // In turn, that means that all nodes at P are equivalent in terms
806 // of observable behavior at N, and we can follow any of them.
807 // FIXME: a more robust solution which does not walk up the tree.
808 continue;
5
←
 Execution continues on line 800
→
809 }
810 SrcBlock = PP.castAs<BlockEdge>().getSrc();
811 SrcState = N->getState();
812 break;
813 }
814
815 assert(SrcBlock && "missing function entry")(static_cast<void> (0));
816
817 // Find the last expression in the predecessor block. That is the
818 // expression that is used for the value of the ternary expression.
819 bool hasValue = false;
820 SVal V;
821
822 for (CFGElement CE : llvm::reverse(*SrcBlock)) {
7
←
Forming reference to null pointer
823 if (Optional<CFGStmt> CS = CE.getAs<CFGStmt>()) {
824 const Expr *ValEx = cast<Expr>(CS->getStmt());
825 ValEx = ValEx->IgnoreParens();
826
827 // For GNU extension '?:' operator, the left hand side will be an
828 // OpaqueValueExpr, so get the underlying expression.
829 if (const OpaqueValueExpr *OpaqueEx = dyn_cast<OpaqueValueExpr>(L))
830 L = OpaqueEx->getSourceExpr();
831
832 // If the last expression in the predecessor block matches true or false
833 // subexpression, get its the value.
834 if (ValEx == L->IgnoreParens() || ValEx == R->IgnoreParens()) {
835 hasValue = true;
836 V = SrcState->getSVal(ValEx, LCtx);
837 }
838 break;
839 }
840 }
841
842 if (!hasValue)
843 V = svalBuilder.conjureSymbolVal(nullptr, Ex, LCtx,
844 currBldrCtx->blockCount());
845
846 // Generate a new node with the binding from the appropriate path.
847 B.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, V, true));
848}
849
850void ExprEngine::
851VisitOffsetOfExpr(const OffsetOfExpr *OOE,
852 ExplodedNode *Pred, ExplodedNodeSet &Dst) {
853 StmtNodeBuilder B(Pred, Dst, *currBldrCtx);
854 Expr::EvalResult Result;
855 if (OOE->EvaluateAsInt(Result, getContext())) {
856 APSInt IV = Result.Val.getInt();
857 assert(IV.getBitWidth() == getContext().getTypeSize(OOE->getType()))(static_cast<void> (0));
858 assert(OOE->getType()->castAs<BuiltinType>()->isInteger())(static_cast<void> (0));
859 assert(IV.isSigned() == OOE->getType()->isSignedIntegerType())(static_cast<void> (0));
860 SVal X = svalBuilder.makeIntVal(IV);
861 B.generateNode(OOE, Pred,
862 Pred->getState()->BindExpr(OOE, Pred->getLocationContext(),
863 X));
864 }
865 // FIXME: Handle the case where __builtin_offsetof is not a constant.
866}
867
868
869void ExprEngine::
870VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *Ex,
871 ExplodedNode *Pred,
872 ExplodedNodeSet &Dst) {
873 // FIXME: Prechecks eventually go in ::Visit().
874 ExplodedNodeSet CheckedSet;
875 getCheckerManager().runCheckersForPreStmt(CheckedSet, Pred, Ex, *this);
876
877 ExplodedNodeSet EvalSet;
878 StmtNodeBuilder Bldr(CheckedSet, EvalSet, *currBldrCtx);
879
880 QualType T = Ex->getTypeOfArgument();
881
882 for (ExplodedNodeSet::iterator I = CheckedSet.begin(), E = CheckedSet.end();
883 I != E; ++I) {
884 if (Ex->getKind() == UETT_SizeOf) {
885 if (!T->isIncompleteType() && !T->isConstantSizeType()) {
886 assert(T->isVariableArrayType() && "Unknown non-constant-sized type.")(static_cast<void> (0));
887
888 // FIXME: Add support for VLA type arguments and VLA expressions.
889 // When that happens, we should probably refactor VLASizeChecker's code.
890 continue;
891 } else if (T->getAs<ObjCObjectType>()) {
892 // Some code tries to take the sizeof an ObjCObjectType, relying that
893 // the compiler has laid out its representation. Just report Unknown
894 // for these.
895 continue;
896 }
897 }
898
899 APSInt Value = Ex->EvaluateKnownConstInt(getContext());
900 CharUnits amt = CharUnits::fromQuantity(Value.getZExtValue());
901
902 ProgramStateRef state = (*I)->getState();
903 state = state->BindExpr(Ex, (*I)->getLocationContext(),
904 svalBuilder.makeIntVal(amt.getQuantity(),
905 Ex->getType()));
906 Bldr.generateNode(Ex, *I, state);
907 }
908
909 getCheckerManager().runCheckersForPostStmt(Dst, EvalSet, Ex, *this);
910}
911
912void ExprEngine::handleUOExtension(ExplodedNodeSet::iterator I,
913 const UnaryOperator *U,
914 StmtNodeBuilder &Bldr) {
915 // FIXME: We can probably just have some magic in Environment::getSVal()
916 // that propagates values, instead of creating a new node here.
917 //
918 // Unary "+" is a no-op, similar to a parentheses. We still have places
919 // where it may be a block-level expression, so we need to
920 // generate an extra node that just propagates the value of the
921 // subexpression.
922 const Expr *Ex = U->getSubExpr()->IgnoreParens();
923 ProgramStateRef state = (*I)->getState();
924 const LocationContext *LCtx = (*I)->getLocationContext();
925 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx,
926 state->getSVal(Ex, LCtx)));
927}
928
929void ExprEngine::VisitUnaryOperator(const UnaryOperator* U, ExplodedNode *Pred,
930 ExplodedNodeSet &Dst) {
931 // FIXME: Prechecks eventually go in ::Visit().
932 ExplodedNodeSet CheckedSet;
933 getCheckerManager().runCheckersForPreStmt(CheckedSet, Pred, U, *this);
934
935 ExplodedNodeSet EvalSet;
936 StmtNodeBuilder Bldr(CheckedSet, EvalSet, *currBldrCtx);
937
938 for (ExplodedNodeSet::iterator I = CheckedSet.begin(), E = CheckedSet.end();
939 I != E; ++I) {
940 switch (U->getOpcode()) {
941 default: {
942 Bldr.takeNodes(*I);
943 ExplodedNodeSet Tmp;
944 VisitIncrementDecrementOperator(U, *I, Tmp);
945 Bldr.addNodes(Tmp);
946 break;
947 }
948 case UO_Real: {
949 const Expr *Ex = U->getSubExpr()->IgnoreParens();
950
951 // FIXME: We don't have complex SValues yet.
952 if (Ex->getType()->isAnyComplexType()) {
953 // Just report "Unknown."
954 break;
955 }
956
957 // For all other types, UO_Real is an identity operation.
958 assert (U->getType() == Ex->getType())(static_cast<void> (0));
959 ProgramStateRef state = (*I)->getState();
960 const LocationContext *LCtx = (*I)->getLocationContext();
961 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx,
962 state->getSVal(Ex, LCtx)));
963 break;
964 }
965
966 case UO_Imag: {
967 const Expr *Ex = U->getSubExpr()->IgnoreParens();
968 // FIXME: We don't have complex SValues yet.
969 if (Ex->getType()->isAnyComplexType()) {
970 // Just report "Unknown."
971 break;
972 }
973 // For all other types, UO_Imag returns 0.
974 ProgramStateRef state = (*I)->getState();
975 const LocationContext *LCtx = (*I)->getLocationContext();
976 SVal X = svalBuilder.makeZeroVal(Ex->getType());
977 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, X));
978 break;
979 }
980
981 case UO_AddrOf: {
982 // Process pointer-to-member address operation.
983 const Expr *Ex = U->getSubExpr()->IgnoreParens();
984 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Ex)) {
985 const ValueDecl *VD = DRE->getDecl();
986
987 if (isa<CXXMethodDecl>(VD) || isa<FieldDecl>(VD) ||
988 isa<IndirectFieldDecl>(VD)) {
989 ProgramStateRef State = (*I)->getState();
990 const LocationContext *LCtx = (*I)->getLocationContext();
991 SVal SV = svalBuilder.getMemberPointer(cast<NamedDecl>(VD));
992 Bldr.generateNode(U, *I, State->BindExpr(U, LCtx, SV));
993 break;
994 }
995 }
996 // Explicitly proceed with default handler for this case cascade.
997 handleUOExtension(I, U, Bldr);
998 break;
999 }
1000 case UO_Plus:
1001 assert(!U->isGLValue())(static_cast<void> (0));
1002 LLVM_FALLTHROUGH[[gnu::fallthrough]];
1003 case UO_Deref:
1004 case UO_Extension: {
1005 handleUOExtension(I, U, Bldr);
1006 break;
1007 }
1008
1009 case UO_LNot:
1010 case UO_Minus:
1011 case UO_Not: {
1012 assert (!U->isGLValue())(static_cast<void> (0));
1013 const Expr *Ex = U->getSubExpr()->IgnoreParens();
1014 ProgramStateRef state = (*I)->getState();
1015 const LocationContext *LCtx = (*I)->getLocationContext();
1016
1017 // Get the value of the subexpression.
1018 SVal V = state->getSVal(Ex, LCtx);
1019
1020 if (V.isUnknownOrUndef()) {
1021 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, V));
1022 break;
1023 }
1024
1025 switch (U->getOpcode()) {
1026 default:
1027 llvm_unreachable("Invalid Opcode.")__builtin_unreachable();
1028 case UO_Not:
1029 // FIXME: Do we need to handle promotions?
1030 state = state->BindExpr(U, LCtx, evalComplement(V.castAs<NonLoc>()));
1031 break;
1032 case UO_Minus:
1033 // FIXME: Do we need to handle promotions?
1034 state = state->BindExpr(U, LCtx, evalMinus(V.castAs<NonLoc>()));
1035 break;
1036 case UO_LNot:
1037 // C99 6.5.3.3: "The expression !E is equivalent to (0==E)."
1038 //
1039 // Note: technically we do "E == 0", but this is the same in the
1040 // transfer functions as "0 == E".
1041 SVal Result;
1042 if (Optional<Loc> LV = V.getAs<Loc>()) {
1043 Loc X = svalBuilder.makeNullWithType(Ex->getType());
1044 Result = evalBinOp(state, BO_EQ, *LV, X, U->getType());
1045 } else if (Ex->getType()->isFloatingType()) {
1046 // FIXME: handle floating point types.
1047 Result = UnknownVal();
1048 } else {
1049 nonloc::ConcreteInt X(getBasicVals().getValue(0, Ex->getType()));
1050 Result = evalBinOp(state, BO_EQ, V.castAs<NonLoc>(), X,
1051 U->getType());
1052 }
1053
1054 state = state->BindExpr(U, LCtx, Result);
1055 break;
1056 }
1057 Bldr.generateNode(U, *I, state);
1058 break;
1059 }
1060 }
1061 }
1062
1063 getCheckerManager().runCheckersForPostStmt(Dst, EvalSet, U, *this);
1064}
1065
1066void ExprEngine::VisitIncrementDecrementOperator(const UnaryOperator* U,
1067 ExplodedNode *Pred,
1068 ExplodedNodeSet &Dst) {
1069 // Handle ++ and -- (both pre- and post-increment).
1070 assert (U->isIncrementDecrementOp())(static_cast<void> (0));
1071 const Expr *Ex = U->getSubExpr()->IgnoreParens();
1072
1073 const LocationContext *LCtx = Pred->getLocationContext();
1074 ProgramStateRef state = Pred->getState();
1075 SVal loc = state->getSVal(Ex, LCtx);
1076
1077 // Perform a load.
1078 ExplodedNodeSet Tmp;
1079 evalLoad(Tmp, U, Ex, Pred, state, loc);
1080
1081 ExplodedNodeSet Dst2;
1082 StmtNodeBuilder Bldr(Tmp, Dst2, *currBldrCtx);
1083 for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end();I!=E;++I) {
1084
1085 state = (*I)->getState();
1086 assert(LCtx == (*I)->getLocationContext())(static_cast<void> (0));
1087 SVal V2_untested = state->getSVal(Ex, LCtx);
1088
1089 // Propagate unknown and undefined values.
1090 if (V2_untested.isUnknownOrUndef()) {
1091 state = state->BindExpr(U, LCtx, V2_untested);
1092
1093 // Perform the store, so that the uninitialized value detection happens.
1094 Bldr.takeNodes(*I);
1095 ExplodedNodeSet Dst3;
1096 evalStore(Dst3, U, Ex, *I, state, loc, V2_untested);
1097 Bldr.addNodes(Dst3);
1098
1099 continue;
1100 }
1101 DefinedSVal V2 = V2_untested.castAs<DefinedSVal>();
1102
1103 // Handle all other values.
1104 BinaryOperator::Opcode Op = U->isIncrementOp() ? BO_Add : BO_Sub;
1105
1106 // If the UnaryOperator has non-location type, use its type to create the
1107 // constant value. If the UnaryOperator has location type, create the
1108 // constant with int type and pointer width.
1109 SVal RHS;
1110 SVal Result;
1111
1112 if (U->getType()->isAnyPointerType())
1113 RHS = svalBuilder.makeArrayIndex(1);
1114 else if (U->getType()->isIntegralOrEnumerationType())
1115 RHS = svalBuilder.makeIntVal(1, U->getType());
1116 else
1117 RHS = UnknownVal();
1118
1119 // The use of an operand of type bool with the ++ operators is deprecated
1120 // but valid until C++17. And if the operand of the ++ operator is of type
1121 // bool, it is set to true until C++17. Note that for '_Bool', it is also
1122 // set to true when it encounters ++ operator.
1123 if (U->getType()->isBooleanType() && U->isIncrementOp())
1124 Result = svalBuilder.makeTruthVal(true, U->getType());
1125 else
1126 Result = evalBinOp(state, Op, V2, RHS, U->getType());
1127
1128 // Conjure a new symbol if necessary to recover precision.
1129 if (Result.isUnknown()){
1130 DefinedOrUnknownSVal SymVal =
1131 svalBuilder.conjureSymbolVal(nullptr, U, LCtx,
1132 currBldrCtx->blockCount());
1133 Result = SymVal;
1134
1135 // If the value is a location, ++/-- should always preserve
1136 // non-nullness. Check if the original value was non-null, and if so
1137 // propagate that constraint.
1138 if (Loc::isLocType(U->getType())) {
1139 DefinedOrUnknownSVal Constraint =
1140 svalBuilder.evalEQ(state, V2,svalBuilder.makeZeroVal(U->getType()));
1141
1142 if (!state->assume(Constraint, true)) {
1143 // It isn't feasible for the original value to be null.
1144 // Propagate this constraint.
1145 Constraint = svalBuilder.evalEQ(state, SymVal,
1146 svalBuilder.makeZeroVal(U->getType()));
1147
1148 state = state->assume(Constraint, false);
1149 assert(state)(static_cast<void> (0));
1150 }
1151 }
1152 }
1153
1154 // Since the lvalue-to-rvalue conversion is explicit in the AST,
1155 // we bind an l-value if the operator is prefix and an lvalue (in C++).
1156 if (U->isGLValue())
1157 state = state->BindExpr(U, LCtx, loc);
1158 else
1159 state = state->BindExpr(U, LCtx, U->isPostfix() ? V2 : Result);
1160
1161 // Perform the store.
1162 Bldr.takeNodes(*I);
1163 ExplodedNodeSet Dst3;
1164 evalStore(Dst3, U, Ex, *I, state, loc, Result);
1165 Bldr.addNodes(Dst3);
1166 }
1167 Dst.insert(Dst2);
1168}