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 // FIXME: Handle floats.
40 // FIXME: Handle structs.
44 NonLoc SValBuilder::makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op,
45 const llvm::APSInt& rhs, QualType type) {
46 // The Environment ensures we always get a persistent APSInt in
47 // BasicValueFactory, so we don't need to get the APSInt from
48 // BasicValueFactory again.
50 assert(!Loc::isLocType(type));
51 return nonloc::SymbolVal(SymMgr.getSymIntExpr(lhs, op, rhs, type));
54 NonLoc SValBuilder::makeNonLoc(const llvm::APSInt& lhs,
55 BinaryOperator::Opcode op, const SymExpr *rhs,
58 assert(!Loc::isLocType(type));
59 return nonloc::SymbolVal(SymMgr.getIntSymExpr(lhs, op, rhs, type));
62 NonLoc SValBuilder::makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op,
63 const SymExpr *rhs, QualType type) {
65 assert(!Loc::isLocType(type));
66 return nonloc::SymbolVal(SymMgr.getSymSymExpr(lhs, op, rhs, type));
69 NonLoc SValBuilder::makeNonLoc(const SymExpr *operand,
70 QualType fromTy, QualType toTy) {
72 assert(!Loc::isLocType(toTy));
73 return nonloc::SymbolVal(SymMgr.getCastSymbol(operand, fromTy, toTy));
76 SVal SValBuilder::convertToArrayIndex(SVal val) {
77 if (val.isUnknownOrUndef())
80 // Common case: we have an appropriately sized integer.
81 if (Optional<nonloc::ConcreteInt> CI = val.getAs<nonloc::ConcreteInt>()) {
82 const llvm::APSInt& I = CI->getValue();
83 if (I.getBitWidth() == ArrayIndexWidth && I.isSigned())
87 return evalCastFromNonLoc(val.castAs<NonLoc>(), ArrayIndexTy);
90 nonloc::ConcreteInt SValBuilder::makeBoolVal(const CXXBoolLiteralExpr *boolean){
91 return makeTruthVal(boolean->getValue());
95 SValBuilder::getRegionValueSymbolVal(const TypedValueRegion* region) {
96 QualType T = region->getValueType();
98 if (!SymbolManager::canSymbolicate(T))
101 SymbolRef sym = SymMgr.getRegionValueSymbol(region);
103 if (Loc::isLocType(T))
104 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
106 return nonloc::SymbolVal(sym);
109 DefinedOrUnknownSVal SValBuilder::conjureSymbolVal(const void *SymbolTag,
111 const LocationContext *LCtx,
113 QualType T = Ex->getType();
115 // Compute the type of the result. If the expression is not an R-value, the
116 // result should be a location.
117 QualType ExType = Ex->getType();
119 T = LCtx->getAnalysisDeclContext()->getASTContext().getPointerType(ExType);
121 return conjureSymbolVal(SymbolTag, Ex, LCtx, T, Count);
124 DefinedOrUnknownSVal SValBuilder::conjureSymbolVal(const void *symbolTag,
126 const LocationContext *LCtx,
129 if (!SymbolManager::canSymbolicate(type))
132 SymbolRef sym = SymMgr.conjureSymbol(expr, LCtx, type, count, symbolTag);
134 if (Loc::isLocType(type))
135 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
137 return nonloc::SymbolVal(sym);
141 DefinedOrUnknownSVal SValBuilder::conjureSymbolVal(const Stmt *stmt,
142 const LocationContext *LCtx,
144 unsigned visitCount) {
145 if (!SymbolManager::canSymbolicate(type))
148 SymbolRef sym = SymMgr.conjureSymbol(stmt, LCtx, type, visitCount);
150 if (Loc::isLocType(type))
151 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
153 return nonloc::SymbolVal(sym);
157 SValBuilder::getConjuredHeapSymbolVal(const Expr *E,
158 const LocationContext *LCtx,
159 unsigned VisitCount) {
160 QualType T = E->getType();
161 assert(Loc::isLocType(T));
162 assert(SymbolManager::canSymbolicate(T));
164 SymbolRef sym = SymMgr.conjureSymbol(E, LCtx, T, VisitCount);
165 return loc::MemRegionVal(MemMgr.getSymbolicHeapRegion(sym));
168 DefinedSVal SValBuilder::getMetadataSymbolVal(const void *symbolTag,
169 const MemRegion *region,
170 const Expr *expr, QualType type,
172 assert(SymbolManager::canSymbolicate(type) && "Invalid metadata symbol type");
175 SymMgr.getMetadataSymbol(region, expr, type, count, symbolTag);
177 if (Loc::isLocType(type))
178 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
180 return nonloc::SymbolVal(sym);
184 SValBuilder::getDerivedRegionValueSymbolVal(SymbolRef parentSymbol,
185 const TypedValueRegion *region) {
186 QualType T = region->getValueType();
188 if (!SymbolManager::canSymbolicate(T))
191 SymbolRef sym = SymMgr.getDerivedSymbol(parentSymbol, region);
193 if (Loc::isLocType(T))
194 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
196 return nonloc::SymbolVal(sym);
199 DefinedSVal SValBuilder::getFunctionPointer(const FunctionDecl *func) {
200 return loc::MemRegionVal(MemMgr.getFunctionTextRegion(func));
203 DefinedSVal SValBuilder::getBlockPointer(const BlockDecl *block,
205 const LocationContext *locContext) {
206 const BlockTextRegion *BC =
207 MemMgr.getBlockTextRegion(block, locTy, locContext->getAnalysisDeclContext());
208 const BlockDataRegion *BD = MemMgr.getBlockDataRegion(BC, locContext);
209 return loc::MemRegionVal(BD);
212 /// Return a memory region for the 'this' object reference.
213 loc::MemRegionVal SValBuilder::getCXXThis(const CXXMethodDecl *D,
214 const StackFrameContext *SFC) {
215 return loc::MemRegionVal(getRegionManager().
216 getCXXThisRegion(D->getThisType(getContext()), SFC));
219 /// Return a memory region for the 'this' object reference.
220 loc::MemRegionVal SValBuilder::getCXXThis(const CXXRecordDecl *D,
221 const StackFrameContext *SFC) {
222 const Type *T = D->getTypeForDecl();
223 QualType PT = getContext().getPointerType(QualType(T, 0));
224 return loc::MemRegionVal(getRegionManager().getCXXThisRegion(PT, SFC));
227 Optional<SVal> SValBuilder::getConstantVal(const Expr *E) {
228 E = E->IgnoreParens();
230 switch (E->getStmtClass()) {
231 // Handle expressions that we treat differently from the AST's constant
233 case Stmt::AddrLabelExprClass:
234 return makeLoc(cast<AddrLabelExpr>(E));
236 case Stmt::CXXScalarValueInitExprClass:
237 case Stmt::ImplicitValueInitExprClass:
238 return makeZeroVal(E->getType());
240 case Stmt::ObjCStringLiteralClass: {
241 const ObjCStringLiteral *SL = cast<ObjCStringLiteral>(E);
242 return makeLoc(getRegionManager().getObjCStringRegion(SL));
245 case Stmt::StringLiteralClass: {
246 const StringLiteral *SL = cast<StringLiteral>(E);
247 return makeLoc(getRegionManager().getStringRegion(SL));
250 // Fast-path some expressions to avoid the overhead of going through the AST's
251 // constant evaluator
252 case Stmt::CharacterLiteralClass: {
253 const CharacterLiteral *C = cast<CharacterLiteral>(E);
254 return makeIntVal(C->getValue(), C->getType());
257 case Stmt::CXXBoolLiteralExprClass:
258 return makeBoolVal(cast<CXXBoolLiteralExpr>(E));
260 case Stmt::IntegerLiteralClass:
261 return makeIntVal(cast<IntegerLiteral>(E));
263 case Stmt::ObjCBoolLiteralExprClass:
264 return makeBoolVal(cast<ObjCBoolLiteralExpr>(E));
266 case Stmt::CXXNullPtrLiteralExprClass:
269 // If we don't have a special case, fall back to the AST's constant evaluator.
271 // Don't try to come up with a value for materialized temporaries.
275 ASTContext &Ctx = getContext();
277 if (E->EvaluateAsInt(Result, Ctx))
278 return makeIntVal(Result);
280 if (Loc::isLocType(E->getType()))
281 if (E->isNullPointerConstant(Ctx, Expr::NPC_ValueDependentIsNotNull))
289 //===----------------------------------------------------------------------===//
291 SVal SValBuilder::makeSymExprValNN(ProgramStateRef State,
292 BinaryOperator::Opcode Op,
293 NonLoc LHS, NonLoc RHS,
295 if (!State->isTainted(RHS) && !State->isTainted(LHS))
298 const SymExpr *symLHS = LHS.getAsSymExpr();
299 const SymExpr *symRHS = RHS.getAsSymExpr();
300 // TODO: When the Max Complexity is reached, we should conjure a symbol
301 // instead of generating an Unknown value and propagate the taint info to it.
302 const unsigned MaxComp = 10000; // 100000 28X
304 if (symLHS && symRHS &&
305 (symLHS->computeComplexity() + symRHS->computeComplexity()) < MaxComp)
306 return makeNonLoc(symLHS, Op, symRHS, ResultTy);
308 if (symLHS && symLHS->computeComplexity() < MaxComp)
309 if (Optional<nonloc::ConcreteInt> rInt = RHS.getAs<nonloc::ConcreteInt>())
310 return makeNonLoc(symLHS, Op, rInt->getValue(), ResultTy);
312 if (symRHS && symRHS->computeComplexity() < MaxComp)
313 if (Optional<nonloc::ConcreteInt> lInt = LHS.getAs<nonloc::ConcreteInt>())
314 return makeNonLoc(lInt->getValue(), Op, symRHS, ResultTy);
320 SVal SValBuilder::evalBinOp(ProgramStateRef state, BinaryOperator::Opcode op,
321 SVal lhs, SVal rhs, QualType type) {
323 if (lhs.isUndef() || rhs.isUndef())
324 return UndefinedVal();
326 if (lhs.isUnknown() || rhs.isUnknown())
329 if (Optional<Loc> LV = lhs.getAs<Loc>()) {
330 if (Optional<Loc> RV = rhs.getAs<Loc>())
331 return evalBinOpLL(state, op, *LV, *RV, type);
333 return evalBinOpLN(state, op, *LV, rhs.castAs<NonLoc>(), type);
336 if (Optional<Loc> RV = rhs.getAs<Loc>()) {
337 // Support pointer arithmetic where the addend is on the left
338 // and the pointer on the right.
339 assert(op == BO_Add);
341 // Commute the operands.
342 return evalBinOpLN(state, op, *RV, lhs.castAs<NonLoc>(), type);
345 return evalBinOpNN(state, op, lhs.castAs<NonLoc>(), rhs.castAs<NonLoc>(),
349 DefinedOrUnknownSVal SValBuilder::evalEQ(ProgramStateRef state,
350 DefinedOrUnknownSVal lhs,
351 DefinedOrUnknownSVal rhs) {
352 return evalBinOp(state, BO_EQ, lhs, rhs, Context.IntTy)
353 .castAs<DefinedOrUnknownSVal>();
356 /// Recursively check if the pointer types are equal modulo const, volatile,
357 /// and restrict qualifiers. Also, assume that all types are similar to 'void'.
358 /// Assumes the input types are canonical.
359 static bool shouldBeModeledWithNoOp(ASTContext &Context, QualType ToTy,
361 while (Context.UnwrapSimilarPointerTypes(ToTy, FromTy)) {
362 Qualifiers Quals1, Quals2;
363 ToTy = Context.getUnqualifiedArrayType(ToTy, Quals1);
364 FromTy = Context.getUnqualifiedArrayType(FromTy, Quals2);
366 // Make sure that non cvr-qualifiers the other qualifiers (e.g., address
367 // spaces) are identical.
368 Quals1.removeCVRQualifiers();
369 Quals2.removeCVRQualifiers();
370 if (Quals1 != Quals2)
374 // If we are casting to void, the 'From' value can be used to represent the
376 if (ToTy->isVoidType())
385 // FIXME: should rewrite according to the cast kind.
386 SVal SValBuilder::evalCast(SVal val, QualType castTy, QualType originalTy) {
387 castTy = Context.getCanonicalType(castTy);
388 originalTy = Context.getCanonicalType(originalTy);
389 if (val.isUnknownOrUndef() || castTy == originalTy)
392 if (castTy->isBooleanType()) {
393 if (val.isUnknownOrUndef())
395 if (val.isConstant())
396 return makeTruthVal(!val.isZeroConstant(), castTy);
397 if (SymbolRef Sym = val.getAsSymbol()) {
398 BasicValueFactory &BVF = getBasicValueFactory();
399 // FIXME: If we had a state here, we could see if the symbol is known to
400 // be zero, but we don't.
401 return makeNonLoc(Sym, BO_NE, BVF.getValue(0, Sym->getType()), castTy);
404 assert(val.getAs<Loc>());
405 return makeTruthVal(true, castTy);
408 // For const casts, casts to void, just propagate the value.
409 if (!castTy->isVariableArrayType() && !originalTy->isVariableArrayType())
410 if (shouldBeModeledWithNoOp(Context, Context.getPointerType(castTy),
411 Context.getPointerType(originalTy)))
414 // Check for casts from pointers to integers.
415 if (castTy->isIntegralOrEnumerationType() && Loc::isLocType(originalTy))
416 return evalCastFromLoc(val.castAs<Loc>(), castTy);
418 // Check for casts from integers to pointers.
419 if (Loc::isLocType(castTy) && originalTy->isIntegralOrEnumerationType()) {
420 if (Optional<nonloc::LocAsInteger> LV = val.getAs<nonloc::LocAsInteger>()) {
421 if (const MemRegion *R = LV->getLoc().getAsRegion()) {
422 StoreManager &storeMgr = StateMgr.getStoreManager();
423 R = storeMgr.castRegion(R, castTy);
424 return R ? SVal(loc::MemRegionVal(R)) : UnknownVal();
428 return dispatchCast(val, castTy);
431 // Just pass through function and block pointers.
432 if (originalTy->isBlockPointerType() || originalTy->isFunctionPointerType()) {
433 assert(Loc::isLocType(castTy));
437 // Check for casts from array type to another type.
438 if (originalTy->isArrayType()) {
439 // We will always decay to a pointer.
440 val = StateMgr.ArrayToPointer(val.castAs<Loc>());
442 // Are we casting from an array to a pointer? If so just pass on
443 // the decayed value.
444 if (castTy->isPointerType() || castTy->isReferenceType())
447 // Are we casting from an array to an integer? If so, cast the decayed
448 // pointer value to an integer.
449 assert(castTy->isIntegralOrEnumerationType());
451 // FIXME: Keep these here for now in case we decide soon that we
452 // need the original decayed type.
453 // QualType elemTy = cast<ArrayType>(originalTy)->getElementType();
454 // QualType pointerTy = C.getPointerType(elemTy);
455 return evalCastFromLoc(val.castAs<Loc>(), castTy);
458 // Check for casts from a region to a specific type.
459 if (const MemRegion *R = val.getAsRegion()) {
460 // Handle other casts of locations to integers.
461 if (castTy->isIntegralOrEnumerationType())
462 return evalCastFromLoc(loc::MemRegionVal(R), castTy);
464 // FIXME: We should handle the case where we strip off view layers to get
465 // to a desugared type.
466 if (!Loc::isLocType(castTy)) {
467 // FIXME: There can be gross cases where one casts the result of a function
468 // (that returns a pointer) to some other value that happens to fit
469 // within that pointer value. We currently have no good way to
470 // model such operations. When this happens, the underlying operation
471 // is that the caller is reasoning about bits. Conceptually we are
472 // layering a "view" of a location on top of those bits. Perhaps
473 // we need to be more lazy about mutual possible views, even on an
474 // SVal? This may be necessary for bit-level reasoning as well.
478 // We get a symbolic function pointer for a dereference of a function
479 // pointer, but it is of function type. Example:
482 // void (*my_func)(int * x);
487 // int f1_a(struct FPRec* foo) {
489 // (*foo->my_func)(&x);
490 // return bar(x)+1; // no-warning
493 assert(Loc::isLocType(originalTy) || originalTy->isFunctionType() ||
494 originalTy->isBlockPointerType() || castTy->isReferenceType());
496 StoreManager &storeMgr = StateMgr.getStoreManager();
498 // Delegate to store manager to get the result of casting a region to a
499 // different type. If the MemRegion* returned is NULL, this expression
500 // Evaluates to UnknownVal.
501 R = storeMgr.castRegion(R, castTy);
502 return R ? SVal(loc::MemRegionVal(R)) : UnknownVal();
505 return dispatchCast(val, castTy);