1 // SValBuilder.cpp - Basic class for all SValBuilder implementations -*- 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 SValBuilder, the base class for all (complete) SValBuilder
13 //===----------------------------------------------------------------------===//
15 #include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h"
16 #include "clang/AST/DeclCXX.h"
17 #include "clang/AST/ExprCXX.h"
18 #include "clang/StaticAnalyzer/Core/PathSensitive/BasicValueFactory.h"
19 #include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
20 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
21 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
23 using namespace clang;
26 //===----------------------------------------------------------------------===//
27 // Basic SVal creation.
28 //===----------------------------------------------------------------------===//
30 void SValBuilder::anchor() { }
32 DefinedOrUnknownSVal SValBuilder::makeZeroVal(QualType type) {
33 if (Loc::isLocType(type))
36 if (type->isIntegralOrEnumerationType())
37 return makeIntVal(0, type);
39 if (type->isArrayType() || type->isRecordType() || type->isVectorType() ||
40 type->isAnyComplexType())
41 return makeCompoundVal(type, BasicVals.getEmptySValList());
43 // FIXME: Handle floats.
47 NonLoc SValBuilder::makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op,
48 const llvm::APSInt& rhs, QualType type) {
49 // The Environment ensures we always get a persistent APSInt in
50 // BasicValueFactory, so we don't need to get the APSInt from
51 // BasicValueFactory again.
53 assert(!Loc::isLocType(type));
54 return nonloc::SymbolVal(SymMgr.getSymIntExpr(lhs, op, rhs, type));
57 NonLoc SValBuilder::makeNonLoc(const llvm::APSInt& lhs,
58 BinaryOperator::Opcode op, const SymExpr *rhs,
61 assert(!Loc::isLocType(type));
62 return nonloc::SymbolVal(SymMgr.getIntSymExpr(lhs, op, rhs, type));
65 NonLoc SValBuilder::makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op,
66 const SymExpr *rhs, QualType type) {
68 assert(!Loc::isLocType(type));
69 return nonloc::SymbolVal(SymMgr.getSymSymExpr(lhs, op, rhs, type));
72 NonLoc SValBuilder::makeNonLoc(const SymExpr *operand,
73 QualType fromTy, QualType toTy) {
75 assert(!Loc::isLocType(toTy));
76 return nonloc::SymbolVal(SymMgr.getCastSymbol(operand, fromTy, toTy));
79 SVal SValBuilder::convertToArrayIndex(SVal val) {
80 if (val.isUnknownOrUndef())
83 // Common case: we have an appropriately sized integer.
84 if (Optional<nonloc::ConcreteInt> CI = val.getAs<nonloc::ConcreteInt>()) {
85 const llvm::APSInt& I = CI->getValue();
86 if (I.getBitWidth() == ArrayIndexWidth && I.isSigned())
90 return evalCastFromNonLoc(val.castAs<NonLoc>(), ArrayIndexTy);
93 nonloc::ConcreteInt SValBuilder::makeBoolVal(const CXXBoolLiteralExpr *boolean){
94 return makeTruthVal(boolean->getValue());
98 SValBuilder::getRegionValueSymbolVal(const TypedValueRegion* region) {
99 QualType T = region->getValueType();
101 if (T->isNullPtrType())
102 return makeZeroVal(T);
104 if (!SymbolManager::canSymbolicate(T))
107 SymbolRef sym = SymMgr.getRegionValueSymbol(region);
109 if (Loc::isLocType(T))
110 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
112 return nonloc::SymbolVal(sym);
115 DefinedOrUnknownSVal SValBuilder::conjureSymbolVal(const void *SymbolTag,
117 const LocationContext *LCtx,
119 QualType T = Ex->getType();
121 if (T->isNullPtrType())
122 return makeZeroVal(T);
124 // Compute the type of the result. If the expression is not an R-value, the
125 // result should be a location.
126 QualType ExType = Ex->getType();
128 T = LCtx->getAnalysisDeclContext()->getASTContext().getPointerType(ExType);
130 return conjureSymbolVal(SymbolTag, Ex, LCtx, T, Count);
133 DefinedOrUnknownSVal SValBuilder::conjureSymbolVal(const void *symbolTag,
135 const LocationContext *LCtx,
138 if (type->isNullPtrType())
139 return makeZeroVal(type);
141 if (!SymbolManager::canSymbolicate(type))
144 SymbolRef sym = SymMgr.conjureSymbol(expr, LCtx, type, count, symbolTag);
146 if (Loc::isLocType(type))
147 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
149 return nonloc::SymbolVal(sym);
153 DefinedOrUnknownSVal SValBuilder::conjureSymbolVal(const Stmt *stmt,
154 const LocationContext *LCtx,
156 unsigned visitCount) {
157 if (type->isNullPtrType())
158 return makeZeroVal(type);
160 if (!SymbolManager::canSymbolicate(type))
163 SymbolRef sym = SymMgr.conjureSymbol(stmt, LCtx, type, visitCount);
165 if (Loc::isLocType(type))
166 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
168 return nonloc::SymbolVal(sym);
172 SValBuilder::getConjuredHeapSymbolVal(const Expr *E,
173 const LocationContext *LCtx,
174 unsigned VisitCount) {
175 QualType T = E->getType();
176 assert(Loc::isLocType(T));
177 assert(SymbolManager::canSymbolicate(T));
178 if (T->isNullPtrType())
179 return makeZeroVal(T);
181 SymbolRef sym = SymMgr.conjureSymbol(E, LCtx, T, VisitCount);
182 return loc::MemRegionVal(MemMgr.getSymbolicHeapRegion(sym));
185 DefinedSVal SValBuilder::getMetadataSymbolVal(const void *symbolTag,
186 const MemRegion *region,
187 const Expr *expr, QualType type,
188 const LocationContext *LCtx,
190 assert(SymbolManager::canSymbolicate(type) && "Invalid metadata symbol type");
193 SymMgr.getMetadataSymbol(region, expr, type, LCtx, count, symbolTag);
195 if (Loc::isLocType(type))
196 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
198 return nonloc::SymbolVal(sym);
202 SValBuilder::getDerivedRegionValueSymbolVal(SymbolRef parentSymbol,
203 const TypedValueRegion *region) {
204 QualType T = region->getValueType();
206 if (T->isNullPtrType())
207 return makeZeroVal(T);
209 if (!SymbolManager::canSymbolicate(T))
212 SymbolRef sym = SymMgr.getDerivedSymbol(parentSymbol, region);
214 if (Loc::isLocType(T))
215 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
217 return nonloc::SymbolVal(sym);
220 DefinedSVal SValBuilder::getMemberPointer(const DeclaratorDecl* DD) {
221 return nonloc::PointerToMember(DD);
224 DefinedSVal SValBuilder::getFunctionPointer(const FunctionDecl *func) {
225 return loc::MemRegionVal(MemMgr.getFunctionCodeRegion(func));
228 DefinedSVal SValBuilder::getBlockPointer(const BlockDecl *block,
230 const LocationContext *locContext,
231 unsigned blockCount) {
232 const BlockCodeRegion *BC =
233 MemMgr.getBlockCodeRegion(block, locTy, locContext->getAnalysisDeclContext());
234 const BlockDataRegion *BD = MemMgr.getBlockDataRegion(BC, locContext,
236 return loc::MemRegionVal(BD);
239 /// Return a memory region for the 'this' object reference.
240 loc::MemRegionVal SValBuilder::getCXXThis(const CXXMethodDecl *D,
241 const StackFrameContext *SFC) {
242 return loc::MemRegionVal(getRegionManager().
243 getCXXThisRegion(D->getThisType(getContext()), SFC));
246 /// Return a memory region for the 'this' object reference.
247 loc::MemRegionVal SValBuilder::getCXXThis(const CXXRecordDecl *D,
248 const StackFrameContext *SFC) {
249 const Type *T = D->getTypeForDecl();
250 QualType PT = getContext().getPointerType(QualType(T, 0));
251 return loc::MemRegionVal(getRegionManager().getCXXThisRegion(PT, SFC));
254 Optional<SVal> SValBuilder::getConstantVal(const Expr *E) {
255 E = E->IgnoreParens();
257 switch (E->getStmtClass()) {
258 // Handle expressions that we treat differently from the AST's constant
260 case Stmt::AddrLabelExprClass:
261 return makeLoc(cast<AddrLabelExpr>(E));
263 case Stmt::CXXScalarValueInitExprClass:
264 case Stmt::ImplicitValueInitExprClass:
265 return makeZeroVal(E->getType());
267 case Stmt::ObjCStringLiteralClass: {
268 const ObjCStringLiteral *SL = cast<ObjCStringLiteral>(E);
269 return makeLoc(getRegionManager().getObjCStringRegion(SL));
272 case Stmt::StringLiteralClass: {
273 const StringLiteral *SL = cast<StringLiteral>(E);
274 return makeLoc(getRegionManager().getStringRegion(SL));
277 // Fast-path some expressions to avoid the overhead of going through the AST's
278 // constant evaluator
279 case Stmt::CharacterLiteralClass: {
280 const CharacterLiteral *C = cast<CharacterLiteral>(E);
281 return makeIntVal(C->getValue(), C->getType());
284 case Stmt::CXXBoolLiteralExprClass:
285 return makeBoolVal(cast<CXXBoolLiteralExpr>(E));
287 case Stmt::TypeTraitExprClass: {
288 const TypeTraitExpr *TE = cast<TypeTraitExpr>(E);
289 return makeTruthVal(TE->getValue(), TE->getType());
292 case Stmt::IntegerLiteralClass:
293 return makeIntVal(cast<IntegerLiteral>(E));
295 case Stmt::ObjCBoolLiteralExprClass:
296 return makeBoolVal(cast<ObjCBoolLiteralExpr>(E));
298 case Stmt::CXXNullPtrLiteralExprClass:
301 case Stmt::ImplicitCastExprClass: {
302 const CastExpr *CE = cast<CastExpr>(E);
303 switch (CE->getCastKind()) {
306 case CK_ArrayToPointerDecay:
308 const Expr *SE = CE->getSubExpr();
309 Optional<SVal> Val = getConstantVal(SE);
312 return evalCast(*Val, CE->getType(), SE->getType());
318 // If we don't have a special case, fall back to the AST's constant evaluator.
320 // Don't try to come up with a value for materialized temporaries.
324 ASTContext &Ctx = getContext();
326 if (E->EvaluateAsInt(Result, Ctx))
327 return makeIntVal(Result);
329 if (Loc::isLocType(E->getType()))
330 if (E->isNullPointerConstant(Ctx, Expr::NPC_ValueDependentIsNotNull))
338 //===----------------------------------------------------------------------===//
340 SVal SValBuilder::makeSymExprValNN(ProgramStateRef State,
341 BinaryOperator::Opcode Op,
342 NonLoc LHS, NonLoc RHS,
344 if (!State->isTainted(RHS) && !State->isTainted(LHS))
347 const SymExpr *symLHS = LHS.getAsSymExpr();
348 const SymExpr *symRHS = RHS.getAsSymExpr();
349 // TODO: When the Max Complexity is reached, we should conjure a symbol
350 // instead of generating an Unknown value and propagate the taint info to it.
351 const unsigned MaxComp = 10000; // 100000 28X
353 if (symLHS && symRHS &&
354 (symLHS->computeComplexity() + symRHS->computeComplexity()) < MaxComp)
355 return makeNonLoc(symLHS, Op, symRHS, ResultTy);
357 if (symLHS && symLHS->computeComplexity() < MaxComp)
358 if (Optional<nonloc::ConcreteInt> rInt = RHS.getAs<nonloc::ConcreteInt>())
359 return makeNonLoc(symLHS, Op, rInt->getValue(), ResultTy);
361 if (symRHS && symRHS->computeComplexity() < MaxComp)
362 if (Optional<nonloc::ConcreteInt> lInt = LHS.getAs<nonloc::ConcreteInt>())
363 return makeNonLoc(lInt->getValue(), Op, symRHS, ResultTy);
369 SVal SValBuilder::evalBinOp(ProgramStateRef state, BinaryOperator::Opcode op,
370 SVal lhs, SVal rhs, QualType type) {
372 if (lhs.isUndef() || rhs.isUndef())
373 return UndefinedVal();
375 if (lhs.isUnknown() || rhs.isUnknown())
378 if (lhs.getAs<nonloc::LazyCompoundVal>() ||
379 rhs.getAs<nonloc::LazyCompoundVal>()) {
383 if (Optional<Loc> LV = lhs.getAs<Loc>()) {
384 if (Optional<Loc> RV = rhs.getAs<Loc>())
385 return evalBinOpLL(state, op, *LV, *RV, type);
387 return evalBinOpLN(state, op, *LV, rhs.castAs<NonLoc>(), type);
390 if (Optional<Loc> RV = rhs.getAs<Loc>()) {
391 // Support pointer arithmetic where the addend is on the left
392 // and the pointer on the right.
393 assert(op == BO_Add);
395 // Commute the operands.
396 return evalBinOpLN(state, op, *RV, lhs.castAs<NonLoc>(), type);
399 return evalBinOpNN(state, op, lhs.castAs<NonLoc>(), rhs.castAs<NonLoc>(),
403 DefinedOrUnknownSVal SValBuilder::evalEQ(ProgramStateRef state,
404 DefinedOrUnknownSVal lhs,
405 DefinedOrUnknownSVal rhs) {
406 return evalBinOp(state, BO_EQ, lhs, rhs, getConditionType())
407 .castAs<DefinedOrUnknownSVal>();
410 /// Recursively check if the pointer types are equal modulo const, volatile,
411 /// and restrict qualifiers. Also, assume that all types are similar to 'void'.
412 /// Assumes the input types are canonical.
413 static bool shouldBeModeledWithNoOp(ASTContext &Context, QualType ToTy,
415 while (Context.UnwrapSimilarPointerTypes(ToTy, FromTy)) {
416 Qualifiers Quals1, Quals2;
417 ToTy = Context.getUnqualifiedArrayType(ToTy, Quals1);
418 FromTy = Context.getUnqualifiedArrayType(FromTy, Quals2);
420 // Make sure that non-cvr-qualifiers the other qualifiers (e.g., address
421 // spaces) are identical.
422 Quals1.removeCVRQualifiers();
423 Quals2.removeCVRQualifiers();
424 if (Quals1 != Quals2)
428 // If we are casting to void, the 'From' value can be used to represent the
430 if (ToTy->isVoidType())
439 // Handles casts of type CK_IntegralCast.
440 // At the moment, this function will redirect to evalCast, except when the range
441 // of the original value is known to be greater than the max of the target type.
442 SVal SValBuilder::evalIntegralCast(ProgramStateRef state, SVal val,
443 QualType castTy, QualType originalTy) {
445 // No truncations if target type is big enough.
446 if (getContext().getTypeSize(castTy) >= getContext().getTypeSize(originalTy))
447 return evalCast(val, castTy, originalTy);
449 const SymExpr *se = val.getAsSymbolicExpression();
450 if (!se) // Let evalCast handle non symbolic expressions.
451 return evalCast(val, castTy, originalTy);
453 // Find the maximum value of the target type.
454 APSIntType ToType(getContext().getTypeSize(castTy),
455 castTy->isUnsignedIntegerType());
456 llvm::APSInt ToTypeMax = ToType.getMaxValue();
457 NonLoc ToTypeMaxVal =
458 makeIntVal(ToTypeMax.isUnsigned() ? ToTypeMax.getZExtValue()
459 : ToTypeMax.getSExtValue(),
462 // Check the range of the symbol being casted against the maximum value of the
464 NonLoc FromVal = val.castAs<NonLoc>();
465 QualType CmpTy = getConditionType();
467 evalBinOpNN(state, BO_LE, FromVal, ToTypeMaxVal, CmpTy).castAs<NonLoc>();
468 ProgramStateRef IsNotTruncated, IsTruncated;
469 std::tie(IsNotTruncated, IsTruncated) = state->assume(CompVal);
470 if (!IsNotTruncated && IsTruncated) {
471 // Symbol is truncated so we evaluate it as a cast.
472 NonLoc CastVal = makeNonLoc(se, originalTy, castTy);
475 return evalCast(val, castTy, originalTy);
478 // FIXME: should rewrite according to the cast kind.
479 SVal SValBuilder::evalCast(SVal val, QualType castTy, QualType originalTy) {
480 castTy = Context.getCanonicalType(castTy);
481 originalTy = Context.getCanonicalType(originalTy);
482 if (val.isUnknownOrUndef() || castTy == originalTy)
485 if (castTy->isBooleanType()) {
486 if (val.isUnknownOrUndef())
488 if (val.isConstant())
489 return makeTruthVal(!val.isZeroConstant(), castTy);
490 if (!Loc::isLocType(originalTy) &&
491 !originalTy->isIntegralOrEnumerationType() &&
492 !originalTy->isMemberPointerType())
494 if (SymbolRef Sym = val.getAsSymbol(true)) {
495 BasicValueFactory &BVF = getBasicValueFactory();
496 // FIXME: If we had a state here, we could see if the symbol is known to
497 // be zero, but we don't.
498 return makeNonLoc(Sym, BO_NE, BVF.getValue(0, Sym->getType()), castTy);
500 // Loc values are not always true, they could be weakly linked functions.
501 if (Optional<Loc> L = val.getAs<Loc>())
502 return evalCastFromLoc(*L, castTy);
504 Loc L = val.castAs<nonloc::LocAsInteger>().getLoc();
505 return evalCastFromLoc(L, castTy);
508 // For const casts, casts to void, just propagate the value.
509 if (!castTy->isVariableArrayType() && !originalTy->isVariableArrayType())
510 if (shouldBeModeledWithNoOp(Context, Context.getPointerType(castTy),
511 Context.getPointerType(originalTy)))
514 // Check for casts from pointers to integers.
515 if (castTy->isIntegralOrEnumerationType() && Loc::isLocType(originalTy))
516 return evalCastFromLoc(val.castAs<Loc>(), castTy);
518 // Check for casts from integers to pointers.
519 if (Loc::isLocType(castTy) && originalTy->isIntegralOrEnumerationType()) {
520 if (Optional<nonloc::LocAsInteger> LV = val.getAs<nonloc::LocAsInteger>()) {
521 if (const MemRegion *R = LV->getLoc().getAsRegion()) {
522 StoreManager &storeMgr = StateMgr.getStoreManager();
523 R = storeMgr.castRegion(R, castTy);
524 return R ? SVal(loc::MemRegionVal(R)) : UnknownVal();
528 return dispatchCast(val, castTy);
531 // Just pass through function and block pointers.
532 if (originalTy->isBlockPointerType() || originalTy->isFunctionPointerType()) {
533 assert(Loc::isLocType(castTy));
537 // Check for casts from array type to another type.
538 if (const ArrayType *arrayT =
539 dyn_cast<ArrayType>(originalTy.getCanonicalType())) {
540 // We will always decay to a pointer.
541 QualType elemTy = arrayT->getElementType();
542 val = StateMgr.ArrayToPointer(val.castAs<Loc>(), elemTy);
544 // Are we casting from an array to a pointer? If so just pass on
545 // the decayed value.
546 if (castTy->isPointerType() || castTy->isReferenceType())
549 // Are we casting from an array to an integer? If so, cast the decayed
550 // pointer value to an integer.
551 assert(castTy->isIntegralOrEnumerationType());
553 // FIXME: Keep these here for now in case we decide soon that we
554 // need the original decayed type.
555 // QualType elemTy = cast<ArrayType>(originalTy)->getElementType();
556 // QualType pointerTy = C.getPointerType(elemTy);
557 return evalCastFromLoc(val.castAs<Loc>(), castTy);
560 // Check for casts from a region to a specific type.
561 if (const MemRegion *R = val.getAsRegion()) {
562 // Handle other casts of locations to integers.
563 if (castTy->isIntegralOrEnumerationType())
564 return evalCastFromLoc(loc::MemRegionVal(R), castTy);
566 // FIXME: We should handle the case where we strip off view layers to get
567 // to a desugared type.
568 if (!Loc::isLocType(castTy)) {
569 // FIXME: There can be gross cases where one casts the result of a function
570 // (that returns a pointer) to some other value that happens to fit
571 // within that pointer value. We currently have no good way to
572 // model such operations. When this happens, the underlying operation
573 // is that the caller is reasoning about bits. Conceptually we are
574 // layering a "view" of a location on top of those bits. Perhaps
575 // we need to be more lazy about mutual possible views, even on an
576 // SVal? This may be necessary for bit-level reasoning as well.
580 // We get a symbolic function pointer for a dereference of a function
581 // pointer, but it is of function type. Example:
584 // void (*my_func)(int * x);
589 // int f1_a(struct FPRec* foo) {
591 // (*foo->my_func)(&x);
592 // return bar(x)+1; // no-warning
595 assert(Loc::isLocType(originalTy) || originalTy->isFunctionType() ||
596 originalTy->isBlockPointerType() || castTy->isReferenceType());
598 StoreManager &storeMgr = StateMgr.getStoreManager();
600 // Delegate to store manager to get the result of casting a region to a
601 // different type. If the MemRegion* returned is NULL, this expression
602 // Evaluates to UnknownVal.
603 R = storeMgr.castRegion(R, castTy);
604 return R ? SVal(loc::MemRegionVal(R)) : UnknownVal();
607 return dispatchCast(val, castTy);