1 //===- SValBuilder.cpp - Basic class for all SValBuilder implementations --===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file defines SValBuilder, the base class for all (complete) SValBuilder
11 // implementations.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h"
16 #include "clang/AST/ASTContext.h"
17 #include "clang/AST/Decl.h"
18 #include "clang/AST/DeclCXX.h"
19 #include "clang/AST/ExprCXX.h"
20 #include "clang/AST/ExprObjC.h"
21 #include "clang/AST/Stmt.h"
22 #include "clang/AST/Type.h"
23 #include "clang/Basic/LLVM.h"
24 #include "clang/Analysis/AnalysisDeclContext.h"
25 #include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
26 #include "clang/StaticAnalyzer/Core/PathSensitive/APSIntType.h"
27 #include "clang/StaticAnalyzer/Core/PathSensitive/BasicValueFactory.h"
28 #include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
29 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
30 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState_Fwd.h"
31 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
32 #include "clang/StaticAnalyzer/Core/PathSensitive/Store.h"
33 #include "clang/StaticAnalyzer/Core/PathSensitive/SubEngine.h"
34 #include "clang/StaticAnalyzer/Core/PathSensitive/SymExpr.h"
35 #include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
36 #include "llvm/ADT/APSInt.h"
37 #include "llvm/ADT/None.h"
38 #include "llvm/ADT/Optional.h"
39 #include "llvm/Support/Casting.h"
40 #include "llvm/Support/Compiler.h"
41 #include <cassert>
42 #include <tuple>
43
44 using namespace clang;
45 using namespace ento;
46
47 //===----------------------------------------------------------------------===//
48 // Basic SVal creation.
49 //===----------------------------------------------------------------------===//
50
anchor()51 void SValBuilder::anchor() {}
52
makeZeroVal(QualType type)53 DefinedOrUnknownSVal SValBuilder::makeZeroVal(QualType type) {
54 if (Loc::isLocType(type))
55 return makeNull();
56
57 if (type->isIntegralOrEnumerationType())
58 return makeIntVal(0, type);
59
60 if (type->isArrayType() || type->isRecordType() || type->isVectorType() ||
61 type->isAnyComplexType())
62 return makeCompoundVal(type, BasicVals.getEmptySValList());
63
64 // FIXME: Handle floats.
65 return UnknownVal();
66 }
67
makeNonLoc(const SymExpr * lhs,BinaryOperator::Opcode op,const llvm::APSInt & rhs,QualType type)68 NonLoc SValBuilder::makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op,
69 const llvm::APSInt& rhs, QualType type) {
70 // The Environment ensures we always get a persistent APSInt in
71 // BasicValueFactory, so we don't need to get the APSInt from
72 // BasicValueFactory again.
73 assert(lhs);
74 assert(!Loc::isLocType(type));
75 return nonloc::SymbolVal(SymMgr.getSymIntExpr(lhs, op, rhs, type));
76 }
77
makeNonLoc(const llvm::APSInt & lhs,BinaryOperator::Opcode op,const SymExpr * rhs,QualType type)78 NonLoc SValBuilder::makeNonLoc(const llvm::APSInt& lhs,
79 BinaryOperator::Opcode op, const SymExpr *rhs,
80 QualType type) {
81 assert(rhs);
82 assert(!Loc::isLocType(type));
83 return nonloc::SymbolVal(SymMgr.getIntSymExpr(lhs, op, rhs, type));
84 }
85
makeNonLoc(const SymExpr * lhs,BinaryOperator::Opcode op,const SymExpr * rhs,QualType type)86 NonLoc SValBuilder::makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op,
87 const SymExpr *rhs, QualType type) {
88 assert(lhs && rhs);
89 assert(!Loc::isLocType(type));
90 return nonloc::SymbolVal(SymMgr.getSymSymExpr(lhs, op, rhs, type));
91 }
92
makeNonLoc(const SymExpr * operand,QualType fromTy,QualType toTy)93 NonLoc SValBuilder::makeNonLoc(const SymExpr *operand,
94 QualType fromTy, QualType toTy) {
95 assert(operand);
96 assert(!Loc::isLocType(toTy));
97 return nonloc::SymbolVal(SymMgr.getCastSymbol(operand, fromTy, toTy));
98 }
99
convertToArrayIndex(SVal val)100 SVal SValBuilder::convertToArrayIndex(SVal val) {
101 if (val.isUnknownOrUndef())
102 return val;
103
104 // Common case: we have an appropriately sized integer.
105 if (Optional<nonloc::ConcreteInt> CI = val.getAs<nonloc::ConcreteInt>()) {
106 const llvm::APSInt& I = CI->getValue();
107 if (I.getBitWidth() == ArrayIndexWidth && I.isSigned())
108 return val;
109 }
110
111 return evalCastFromNonLoc(val.castAs<NonLoc>(), ArrayIndexTy);
112 }
113
makeBoolVal(const CXXBoolLiteralExpr * boolean)114 nonloc::ConcreteInt SValBuilder::makeBoolVal(const CXXBoolLiteralExpr *boolean){
115 return makeTruthVal(boolean->getValue());
116 }
117
118 DefinedOrUnknownSVal
getRegionValueSymbolVal(const TypedValueRegion * region)119 SValBuilder::getRegionValueSymbolVal(const TypedValueRegion *region) {
120 QualType T = region->getValueType();
121
122 if (T->isNullPtrType())
123 return makeZeroVal(T);
124
125 if (!SymbolManager::canSymbolicate(T))
126 return UnknownVal();
127
128 SymbolRef sym = SymMgr.getRegionValueSymbol(region);
129
130 if (Loc::isLocType(T))
131 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
132
133 return nonloc::SymbolVal(sym);
134 }
135
conjureSymbolVal(const void * SymbolTag,const Expr * Ex,const LocationContext * LCtx,unsigned Count)136 DefinedOrUnknownSVal SValBuilder::conjureSymbolVal(const void *SymbolTag,
137 const Expr *Ex,
138 const LocationContext *LCtx,
139 unsigned Count) {
140 QualType T = Ex->getType();
141
142 if (T->isNullPtrType())
143 return makeZeroVal(T);
144
145 // Compute the type of the result. If the expression is not an R-value, the
146 // result should be a location.
147 QualType ExType = Ex->getType();
148 if (Ex->isGLValue())
149 T = LCtx->getAnalysisDeclContext()->getASTContext().getPointerType(ExType);
150
151 return conjureSymbolVal(SymbolTag, Ex, LCtx, T, Count);
152 }
153
conjureSymbolVal(const void * symbolTag,const Expr * expr,const LocationContext * LCtx,QualType type,unsigned count)154 DefinedOrUnknownSVal SValBuilder::conjureSymbolVal(const void *symbolTag,
155 const Expr *expr,
156 const LocationContext *LCtx,
157 QualType type,
158 unsigned count) {
159 if (type->isNullPtrType())
160 return makeZeroVal(type);
161
162 if (!SymbolManager::canSymbolicate(type))
163 return UnknownVal();
164
165 SymbolRef sym = SymMgr.conjureSymbol(expr, LCtx, type, count, symbolTag);
166
167 if (Loc::isLocType(type))
168 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
169
170 return nonloc::SymbolVal(sym);
171 }
172
conjureSymbolVal(const Stmt * stmt,const LocationContext * LCtx,QualType type,unsigned visitCount)173 DefinedOrUnknownSVal SValBuilder::conjureSymbolVal(const Stmt *stmt,
174 const LocationContext *LCtx,
175 QualType type,
176 unsigned visitCount) {
177 if (type->isNullPtrType())
178 return makeZeroVal(type);
179
180 if (!SymbolManager::canSymbolicate(type))
181 return UnknownVal();
182
183 SymbolRef sym = SymMgr.conjureSymbol(stmt, LCtx, type, visitCount);
184
185 if (Loc::isLocType(type))
186 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
187
188 return nonloc::SymbolVal(sym);
189 }
190
191 DefinedOrUnknownSVal
getConjuredHeapSymbolVal(const Expr * E,const LocationContext * LCtx,unsigned VisitCount)192 SValBuilder::getConjuredHeapSymbolVal(const Expr *E,
193 const LocationContext *LCtx,
194 unsigned VisitCount) {
195 QualType T = E->getType();
196 assert(Loc::isLocType(T));
197 assert(SymbolManager::canSymbolicate(T));
198 if (T->isNullPtrType())
199 return makeZeroVal(T);
200
201 SymbolRef sym = SymMgr.conjureSymbol(E, LCtx, T, VisitCount);
202 return loc::MemRegionVal(MemMgr.getSymbolicHeapRegion(sym));
203 }
204
getMetadataSymbolVal(const void * symbolTag,const MemRegion * region,const Expr * expr,QualType type,const LocationContext * LCtx,unsigned count)205 DefinedSVal SValBuilder::getMetadataSymbolVal(const void *symbolTag,
206 const MemRegion *region,
207 const Expr *expr, QualType type,
208 const LocationContext *LCtx,
209 unsigned count) {
210 assert(SymbolManager::canSymbolicate(type) && "Invalid metadata symbol type");
211
212 SymbolRef sym =
213 SymMgr.getMetadataSymbol(region, expr, type, LCtx, count, symbolTag);
214
215 if (Loc::isLocType(type))
216 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
217
218 return nonloc::SymbolVal(sym);
219 }
220
221 DefinedOrUnknownSVal
getDerivedRegionValueSymbolVal(SymbolRef parentSymbol,const TypedValueRegion * region)222 SValBuilder::getDerivedRegionValueSymbolVal(SymbolRef parentSymbol,
223 const TypedValueRegion *region) {
224 QualType T = region->getValueType();
225
226 if (T->isNullPtrType())
227 return makeZeroVal(T);
228
229 if (!SymbolManager::canSymbolicate(T))
230 return UnknownVal();
231
232 SymbolRef sym = SymMgr.getDerivedSymbol(parentSymbol, region);
233
234 if (Loc::isLocType(T))
235 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
236
237 return nonloc::SymbolVal(sym);
238 }
239
getMemberPointer(const DeclaratorDecl * DD)240 DefinedSVal SValBuilder::getMemberPointer(const DeclaratorDecl *DD) {
241 assert(!DD || isa<CXXMethodDecl>(DD) || isa<FieldDecl>(DD));
242
243 if (const auto *MD = dyn_cast_or_null<CXXMethodDecl>(DD)) {
244 // Sema treats pointers to static member functions as have function pointer
245 // type, so return a function pointer for the method.
246 // We don't need to play a similar trick for static member fields
247 // because these are represented as plain VarDecls and not FieldDecls
248 // in the AST.
249 if (MD->isStatic())
250 return getFunctionPointer(MD);
251 }
252
253 return nonloc::PointerToMember(DD);
254 }
255
getFunctionPointer(const FunctionDecl * func)256 DefinedSVal SValBuilder::getFunctionPointer(const FunctionDecl *func) {
257 return loc::MemRegionVal(MemMgr.getFunctionCodeRegion(func));
258 }
259
getBlockPointer(const BlockDecl * block,CanQualType locTy,const LocationContext * locContext,unsigned blockCount)260 DefinedSVal SValBuilder::getBlockPointer(const BlockDecl *block,
261 CanQualType locTy,
262 const LocationContext *locContext,
263 unsigned blockCount) {
264 const BlockCodeRegion *BC =
265 MemMgr.getBlockCodeRegion(block, locTy, locContext->getAnalysisDeclContext());
266 const BlockDataRegion *BD = MemMgr.getBlockDataRegion(BC, locContext,
267 blockCount);
268 return loc::MemRegionVal(BD);
269 }
270
271 /// Return a memory region for the 'this' object reference.
getCXXThis(const CXXMethodDecl * D,const StackFrameContext * SFC)272 loc::MemRegionVal SValBuilder::getCXXThis(const CXXMethodDecl *D,
273 const StackFrameContext *SFC) {
274 return loc::MemRegionVal(
275 getRegionManager().getCXXThisRegion(D->getThisType(), SFC));
276 }
277
278 /// Return a memory region for the 'this' object reference.
getCXXThis(const CXXRecordDecl * D,const StackFrameContext * SFC)279 loc::MemRegionVal SValBuilder::getCXXThis(const CXXRecordDecl *D,
280 const StackFrameContext *SFC) {
281 const Type *T = D->getTypeForDecl();
282 QualType PT = getContext().getPointerType(QualType(T, 0));
283 return loc::MemRegionVal(getRegionManager().getCXXThisRegion(PT, SFC));
284 }
285
getConstantVal(const Expr * E)286 Optional<SVal> SValBuilder::getConstantVal(const Expr *E) {
287 E = E->IgnoreParens();
288
289 switch (E->getStmtClass()) {
290 // Handle expressions that we treat differently from the AST's constant
291 // evaluator.
292 case Stmt::AddrLabelExprClass:
293 return makeLoc(cast<AddrLabelExpr>(E));
294
295 case Stmt::CXXScalarValueInitExprClass:
296 case Stmt::ImplicitValueInitExprClass:
297 return makeZeroVal(E->getType());
298
299 case Stmt::ObjCStringLiteralClass: {
300 const auto *SL = cast<ObjCStringLiteral>(E);
301 return makeLoc(getRegionManager().getObjCStringRegion(SL));
302 }
303
304 case Stmt::StringLiteralClass: {
305 const auto *SL = cast<StringLiteral>(E);
306 return makeLoc(getRegionManager().getStringRegion(SL));
307 }
308
309 // Fast-path some expressions to avoid the overhead of going through the AST's
310 // constant evaluator
311 case Stmt::CharacterLiteralClass: {
312 const auto *C = cast<CharacterLiteral>(E);
313 return makeIntVal(C->getValue(), C->getType());
314 }
315
316 case Stmt::CXXBoolLiteralExprClass:
317 return makeBoolVal(cast<CXXBoolLiteralExpr>(E));
318
319 case Stmt::TypeTraitExprClass: {
320 const auto *TE = cast<TypeTraitExpr>(E);
321 return makeTruthVal(TE->getValue(), TE->getType());
322 }
323
324 case Stmt::IntegerLiteralClass:
325 return makeIntVal(cast<IntegerLiteral>(E));
326
327 case Stmt::ObjCBoolLiteralExprClass:
328 return makeBoolVal(cast<ObjCBoolLiteralExpr>(E));
329
330 case Stmt::CXXNullPtrLiteralExprClass:
331 return makeNull();
332
333 case Stmt::CStyleCastExprClass:
334 case Stmt::CXXFunctionalCastExprClass:
335 case Stmt::CXXConstCastExprClass:
336 case Stmt::CXXReinterpretCastExprClass:
337 case Stmt::CXXStaticCastExprClass:
338 case Stmt::ImplicitCastExprClass: {
339 const auto *CE = cast<CastExpr>(E);
340 switch (CE->getCastKind()) {
341 default:
342 break;
343 case CK_ArrayToPointerDecay:
344 case CK_IntegralToPointer:
345 case CK_NoOp:
346 case CK_BitCast: {
347 const Expr *SE = CE->getSubExpr();
348 Optional<SVal> Val = getConstantVal(SE);
349 if (!Val)
350 return None;
351 return evalCast(*Val, CE->getType(), SE->getType());
352 }
353 }
354 // FALLTHROUGH
355 LLVM_FALLTHROUGH;
356 }
357
358 // If we don't have a special case, fall back to the AST's constant evaluator.
359 default: {
360 // Don't try to come up with a value for materialized temporaries.
361 if (E->isGLValue())
362 return None;
363
364 ASTContext &Ctx = getContext();
365 Expr::EvalResult Result;
366 if (E->EvaluateAsInt(Result, Ctx))
367 return makeIntVal(Result.Val.getInt());
368
369 if (Loc::isLocType(E->getType()))
370 if (E->isNullPointerConstant(Ctx, Expr::NPC_ValueDependentIsNotNull))
371 return makeNull();
372
373 return None;
374 }
375 }
376 }
377
makeSymExprValNN(BinaryOperator::Opcode Op,NonLoc LHS,NonLoc RHS,QualType ResultTy)378 SVal SValBuilder::makeSymExprValNN(BinaryOperator::Opcode Op,
379 NonLoc LHS, NonLoc RHS,
380 QualType ResultTy) {
381 const SymExpr *symLHS = LHS.getAsSymExpr();
382 const SymExpr *symRHS = RHS.getAsSymExpr();
383
384 // TODO: When the Max Complexity is reached, we should conjure a symbol
385 // instead of generating an Unknown value and propagate the taint info to it.
386 const unsigned MaxComp = StateMgr.getOwningEngine()
387 .getAnalysisManager()
388 .options.MaxSymbolComplexity;
389
390 if (symLHS && symRHS &&
391 (symLHS->computeComplexity() + symRHS->computeComplexity()) < MaxComp)
392 return makeNonLoc(symLHS, Op, symRHS, ResultTy);
393
394 if (symLHS && symLHS->computeComplexity() < MaxComp)
395 if (Optional<nonloc::ConcreteInt> rInt = RHS.getAs<nonloc::ConcreteInt>())
396 return makeNonLoc(symLHS, Op, rInt->getValue(), ResultTy);
397
398 if (symRHS && symRHS->computeComplexity() < MaxComp)
399 if (Optional<nonloc::ConcreteInt> lInt = LHS.getAs<nonloc::ConcreteInt>())
400 return makeNonLoc(lInt->getValue(), Op, symRHS, ResultTy);
401
402 return UnknownVal();
403 }
404
evalBinOp(ProgramStateRef state,BinaryOperator::Opcode op,SVal lhs,SVal rhs,QualType type)405 SVal SValBuilder::evalBinOp(ProgramStateRef state, BinaryOperator::Opcode op,
406 SVal lhs, SVal rhs, QualType type) {
407 if (lhs.isUndef() || rhs.isUndef())
408 return UndefinedVal();
409
410 if (lhs.isUnknown() || rhs.isUnknown())
411 return UnknownVal();
412
413 if (lhs.getAs<nonloc::LazyCompoundVal>() ||
414 rhs.getAs<nonloc::LazyCompoundVal>()) {
415 return UnknownVal();
416 }
417
418 if (Optional<Loc> LV = lhs.getAs<Loc>()) {
419 if (Optional<Loc> RV = rhs.getAs<Loc>())
420 return evalBinOpLL(state, op, *LV, *RV, type);
421
422 return evalBinOpLN(state, op, *LV, rhs.castAs<NonLoc>(), type);
423 }
424
425 if (Optional<Loc> RV = rhs.getAs<Loc>()) {
426 // Support pointer arithmetic where the addend is on the left
427 // and the pointer on the right.
428 assert(op == BO_Add);
429
430 // Commute the operands.
431 return evalBinOpLN(state, op, *RV, lhs.castAs<NonLoc>(), type);
432 }
433
434 return evalBinOpNN(state, op, lhs.castAs<NonLoc>(), rhs.castAs<NonLoc>(),
435 type);
436 }
437
areEqual(ProgramStateRef state,SVal lhs,SVal rhs)438 ConditionTruthVal SValBuilder::areEqual(ProgramStateRef state, SVal lhs,
439 SVal rhs) {
440 return state->isNonNull(evalEQ(state, lhs, rhs));
441 }
442
evalEQ(ProgramStateRef state,SVal lhs,SVal rhs)443 SVal SValBuilder::evalEQ(ProgramStateRef state, SVal lhs, SVal rhs) {
444 return evalBinOp(state, BO_EQ, lhs, rhs, getConditionType());
445 }
446
evalEQ(ProgramStateRef state,DefinedOrUnknownSVal lhs,DefinedOrUnknownSVal rhs)447 DefinedOrUnknownSVal SValBuilder::evalEQ(ProgramStateRef state,
448 DefinedOrUnknownSVal lhs,
449 DefinedOrUnknownSVal rhs) {
450 return evalEQ(state, static_cast<SVal>(lhs), static_cast<SVal>(rhs))
451 .castAs<DefinedOrUnknownSVal>();
452 }
453
454 /// Recursively check if the pointer types are equal modulo const, volatile,
455 /// and restrict qualifiers. Also, assume that all types are similar to 'void'.
456 /// Assumes the input types are canonical.
shouldBeModeledWithNoOp(ASTContext & Context,QualType ToTy,QualType FromTy)457 static bool shouldBeModeledWithNoOp(ASTContext &Context, QualType ToTy,
458 QualType FromTy) {
459 while (Context.UnwrapSimilarTypes(ToTy, FromTy)) {
460 Qualifiers Quals1, Quals2;
461 ToTy = Context.getUnqualifiedArrayType(ToTy, Quals1);
462 FromTy = Context.getUnqualifiedArrayType(FromTy, Quals2);
463
464 // Make sure that non-cvr-qualifiers the other qualifiers (e.g., address
465 // spaces) are identical.
466 Quals1.removeCVRQualifiers();
467 Quals2.removeCVRQualifiers();
468 if (Quals1 != Quals2)
469 return false;
470 }
471
472 // If we are casting to void, the 'From' value can be used to represent the
473 // 'To' value.
474 //
475 // FIXME: Doing this after unwrapping the types doesn't make any sense. A
476 // cast from 'int**' to 'void**' is not special in the way that a cast from
477 // 'int*' to 'void*' is.
478 if (ToTy->isVoidType())
479 return true;
480
481 if (ToTy != FromTy)
482 return false;
483
484 return true;
485 }
486
487 // Handles casts of type CK_IntegralCast.
488 // At the moment, this function will redirect to evalCast, except when the range
489 // of the original value is known to be greater than the max of the target type.
evalIntegralCast(ProgramStateRef state,SVal val,QualType castTy,QualType originalTy)490 SVal SValBuilder::evalIntegralCast(ProgramStateRef state, SVal val,
491 QualType castTy, QualType originalTy) {
492 // No truncations if target type is big enough.
493 if (getContext().getTypeSize(castTy) >= getContext().getTypeSize(originalTy))
494 return evalCast(val, castTy, originalTy);
495
496 const SymExpr *se = val.getAsSymbolicExpression();
497 if (!se) // Let evalCast handle non symbolic expressions.
498 return evalCast(val, castTy, originalTy);
499
500 // Find the maximum value of the target type.
501 APSIntType ToType(getContext().getTypeSize(castTy),
502 castTy->isUnsignedIntegerType());
503 llvm::APSInt ToTypeMax = ToType.getMaxValue();
504 NonLoc ToTypeMaxVal =
505 makeIntVal(ToTypeMax.isUnsigned() ? ToTypeMax.getZExtValue()
506 : ToTypeMax.getSExtValue(),
507 castTy)
508 .castAs<NonLoc>();
509 // Check the range of the symbol being casted against the maximum value of the
510 // target type.
511 NonLoc FromVal = val.castAs<NonLoc>();
512 QualType CmpTy = getConditionType();
513 NonLoc CompVal =
514 evalBinOpNN(state, BO_LE, FromVal, ToTypeMaxVal, CmpTy).castAs<NonLoc>();
515 ProgramStateRef IsNotTruncated, IsTruncated;
516 std::tie(IsNotTruncated, IsTruncated) = state->assume(CompVal);
517 if (!IsNotTruncated && IsTruncated) {
518 // Symbol is truncated so we evaluate it as a cast.
519 NonLoc CastVal = makeNonLoc(se, originalTy, castTy);
520 return CastVal;
521 }
522 return evalCast(val, castTy, originalTy);
523 }
524
525 // FIXME: should rewrite according to the cast kind.
evalCast(SVal val,QualType castTy,QualType originalTy)526 SVal SValBuilder::evalCast(SVal val, QualType castTy, QualType originalTy) {
527 castTy = Context.getCanonicalType(castTy);
528 originalTy = Context.getCanonicalType(originalTy);
529 if (val.isUnknownOrUndef() || castTy == originalTy)
530 return val;
531
532 if (castTy->isBooleanType()) {
533 if (val.isUnknownOrUndef())
534 return val;
535 if (val.isConstant())
536 return makeTruthVal(!val.isZeroConstant(), castTy);
537 if (!Loc::isLocType(originalTy) &&
538 !originalTy->isIntegralOrEnumerationType() &&
539 !originalTy->isMemberPointerType())
540 return UnknownVal();
541 if (SymbolRef Sym = val.getAsSymbol(true)) {
542 BasicValueFactory &BVF = getBasicValueFactory();
543 // FIXME: If we had a state here, we could see if the symbol is known to
544 // be zero, but we don't.
545 return makeNonLoc(Sym, BO_NE, BVF.getValue(0, Sym->getType()), castTy);
546 }
547 // Loc values are not always true, they could be weakly linked functions.
548 if (Optional<Loc> L = val.getAs<Loc>())
549 return evalCastFromLoc(*L, castTy);
550
551 Loc L = val.castAs<nonloc::LocAsInteger>().getLoc();
552 return evalCastFromLoc(L, castTy);
553 }
554
555 // For const casts, casts to void, just propagate the value.
556 if (!castTy->isVariableArrayType() && !originalTy->isVariableArrayType())
557 if (shouldBeModeledWithNoOp(Context, Context.getPointerType(castTy),
558 Context.getPointerType(originalTy)))
559 return val;
560
561 // Check for casts from pointers to integers.
562 if (castTy->isIntegralOrEnumerationType() && Loc::isLocType(originalTy))
563 return evalCastFromLoc(val.castAs<Loc>(), castTy);
564
565 // Check for casts from integers to pointers.
566 if (Loc::isLocType(castTy) && originalTy->isIntegralOrEnumerationType()) {
567 if (Optional<nonloc::LocAsInteger> LV = val.getAs<nonloc::LocAsInteger>()) {
568 if (const MemRegion *R = LV->getLoc().getAsRegion()) {
569 StoreManager &storeMgr = StateMgr.getStoreManager();
570 R = storeMgr.castRegion(R, castTy);
571 return R ? SVal(loc::MemRegionVal(R)) : UnknownVal();
572 }
573 return LV->getLoc();
574 }
575 return dispatchCast(val, castTy);
576 }
577
578 // Just pass through function and block pointers.
579 if (originalTy->isBlockPointerType() || originalTy->isFunctionPointerType()) {
580 assert(Loc::isLocType(castTy));
581 return val;
582 }
583
584 // Check for casts from array type to another type.
585 if (const auto *arrayT =
586 dyn_cast<ArrayType>(originalTy.getCanonicalType())) {
587 // We will always decay to a pointer.
588 QualType elemTy = arrayT->getElementType();
589 val = StateMgr.ArrayToPointer(val.castAs<Loc>(), elemTy);
590
591 // Are we casting from an array to a pointer? If so just pass on
592 // the decayed value.
593 if (castTy->isPointerType() || castTy->isReferenceType())
594 return val;
595
596 // Are we casting from an array to an integer? If so, cast the decayed
597 // pointer value to an integer.
598 assert(castTy->isIntegralOrEnumerationType());
599
600 // FIXME: Keep these here for now in case we decide soon that we
601 // need the original decayed type.
602 // QualType elemTy = cast<ArrayType>(originalTy)->getElementType();
603 // QualType pointerTy = C.getPointerType(elemTy);
604 return evalCastFromLoc(val.castAs<Loc>(), castTy);
605 }
606
607 // Check for casts from a region to a specific type.
608 if (const MemRegion *R = val.getAsRegion()) {
609 // Handle other casts of locations to integers.
610 if (castTy->isIntegralOrEnumerationType())
611 return evalCastFromLoc(loc::MemRegionVal(R), castTy);
612
613 // FIXME: We should handle the case where we strip off view layers to get
614 // to a desugared type.
615 if (!Loc::isLocType(castTy)) {
616 // FIXME: There can be gross cases where one casts the result of a function
617 // (that returns a pointer) to some other value that happens to fit
618 // within that pointer value. We currently have no good way to
619 // model such operations. When this happens, the underlying operation
620 // is that the caller is reasoning about bits. Conceptually we are
621 // layering a "view" of a location on top of those bits. Perhaps
622 // we need to be more lazy about mutual possible views, even on an
623 // SVal? This may be necessary for bit-level reasoning as well.
624 return UnknownVal();
625 }
626
627 // We get a symbolic function pointer for a dereference of a function
628 // pointer, but it is of function type. Example:
629
630 // struct FPRec {
631 // void (*my_func)(int * x);
632 // };
633 //
634 // int bar(int x);
635 //
636 // int f1_a(struct FPRec* foo) {
637 // int x;
638 // (*foo->my_func)(&x);
639 // return bar(x)+1; // no-warning
640 // }
641
642 assert(Loc::isLocType(originalTy) || originalTy->isFunctionType() ||
643 originalTy->isBlockPointerType() || castTy->isReferenceType());
644
645 StoreManager &storeMgr = StateMgr.getStoreManager();
646
647 // Delegate to store manager to get the result of casting a region to a
648 // different type. If the MemRegion* returned is NULL, this expression
649 // Evaluates to UnknownVal.
650 R = storeMgr.castRegion(R, castTy);
651 return R ? SVal(loc::MemRegionVal(R)) : UnknownVal();
652 }
653
654 return dispatchCast(val, castTy);
655 }
656