// SimpleSValBuilder.cpp - A basic SValBuilder -----------------------*- C++ -*- // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file defines SimpleSValBuilder, a basic implementation of SValBuilder. // //===----------------------------------------------------------------------===// #include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h" #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h" using namespace clang; using namespace ento; namespace { class SimpleSValBuilder : public SValBuilder { protected: virtual SVal dispatchCast(SVal val, QualType castTy); virtual SVal evalCastFromNonLoc(NonLoc val, QualType castTy); virtual SVal evalCastFromLoc(Loc val, QualType castTy); public: SimpleSValBuilder(llvm::BumpPtrAllocator &alloc, ASTContext &context, ProgramStateManager &stateMgr) : SValBuilder(alloc, context, stateMgr) {} virtual ~SimpleSValBuilder() {} virtual SVal evalMinus(NonLoc val); virtual SVal evalComplement(NonLoc val); virtual SVal evalBinOpNN(ProgramStateRef state, BinaryOperator::Opcode op, NonLoc lhs, NonLoc rhs, QualType resultTy); virtual SVal evalBinOpLL(ProgramStateRef state, BinaryOperator::Opcode op, Loc lhs, Loc rhs, QualType resultTy); virtual SVal evalBinOpLN(ProgramStateRef state, BinaryOperator::Opcode op, Loc lhs, NonLoc rhs, QualType resultTy); /// getKnownValue - evaluates a given SVal. If the SVal has only one possible /// (integer) value, that value is returned. Otherwise, returns NULL. virtual const llvm::APSInt *getKnownValue(ProgramStateRef state, SVal V); SVal MakeSymIntVal(const SymExpr *LHS, BinaryOperator::Opcode op, const llvm::APSInt &RHS, QualType resultTy); }; } // end anonymous namespace SValBuilder *ento::createSimpleSValBuilder(llvm::BumpPtrAllocator &alloc, ASTContext &context, ProgramStateManager &stateMgr) { return new SimpleSValBuilder(alloc, context, stateMgr); } //===----------------------------------------------------------------------===// // Transfer function for Casts. //===----------------------------------------------------------------------===// SVal SimpleSValBuilder::dispatchCast(SVal Val, QualType CastTy) { assert(isa(&Val) || isa(&Val)); return isa(Val) ? evalCastFromLoc(cast(Val), CastTy) : evalCastFromNonLoc(cast(Val), CastTy); } SVal SimpleSValBuilder::evalCastFromNonLoc(NonLoc val, QualType castTy) { bool isLocType = Loc::isLocType(castTy); if (nonloc::LocAsInteger *LI = dyn_cast(&val)) { if (isLocType) return LI->getLoc(); // FIXME: Correctly support promotions/truncations. unsigned castSize = Context.getTypeSize(castTy); if (castSize == LI->getNumBits()) return val; return makeLocAsInteger(LI->getLoc(), castSize); } if (const SymExpr *se = val.getAsSymbolicExpression()) { QualType T = Context.getCanonicalType(se->getType(Context)); // If types are the same or both are integers, ignore the cast. // FIXME: Remove this hack when we support symbolic truncation/extension. // HACK: If both castTy and T are integers, ignore the cast. This is // not a permanent solution. Eventually we want to precisely handle // extension/truncation of symbolic integers. This prevents us from losing // precision when we assign 'x = y' and 'y' is symbolic and x and y are // different integer types. if (haveSameType(T, castTy)) return val; if (!isLocType) return makeNonLoc(se, T, castTy); return UnknownVal(); } // If value is a non integer constant, produce unknown. if (!isa(val)) return UnknownVal(); // Only handle casts from integers to integers - if val is an integer constant // being cast to a non integer type, produce unknown. if (!isLocType && !castTy->isIntegerType()) return UnknownVal(); llvm::APSInt i = cast(val).getValue(); i.setIsUnsigned(castTy->isUnsignedIntegerOrEnumerationType() || Loc::isLocType(castTy)); i = i.extOrTrunc(Context.getTypeSize(castTy)); if (isLocType) return makeIntLocVal(i); else return makeIntVal(i); } SVal SimpleSValBuilder::evalCastFromLoc(Loc val, QualType castTy) { // Casts from pointers -> pointers, just return the lval. // // Casts from pointers -> references, just return the lval. These // can be introduced by the frontend for corner cases, e.g // casting from va_list* to __builtin_va_list&. // if (Loc::isLocType(castTy) || castTy->isReferenceType()) return val; // FIXME: Handle transparent unions where a value can be "transparently" // lifted into a union type. if (castTy->isUnionType()) return UnknownVal(); if (castTy->isIntegerType()) { unsigned BitWidth = Context.getTypeSize(castTy); if (!isa(val)) return makeLocAsInteger(val, BitWidth); llvm::APSInt i = cast(val).getValue(); i.setIsUnsigned(castTy->isUnsignedIntegerOrEnumerationType() || Loc::isLocType(castTy)); i = i.extOrTrunc(BitWidth); return makeIntVal(i); } // All other cases: return 'UnknownVal'. This includes casting pointers // to floats, which is probably badness it itself, but this is a good // intermediate solution until we do something better. return UnknownVal(); } //===----------------------------------------------------------------------===// // Transfer function for unary operators. //===----------------------------------------------------------------------===// SVal SimpleSValBuilder::evalMinus(NonLoc val) { switch (val.getSubKind()) { case nonloc::ConcreteIntKind: return cast(val).evalMinus(*this); default: return UnknownVal(); } } SVal SimpleSValBuilder::evalComplement(NonLoc X) { switch (X.getSubKind()) { case nonloc::ConcreteIntKind: return cast(X).evalComplement(*this); default: return UnknownVal(); } } //===----------------------------------------------------------------------===// // Transfer function for binary operators. //===----------------------------------------------------------------------===// static BinaryOperator::Opcode NegateComparison(BinaryOperator::Opcode op) { switch (op) { default: llvm_unreachable("Invalid opcode."); case BO_LT: return BO_GE; case BO_GT: return BO_LE; case BO_LE: return BO_GT; case BO_GE: return BO_LT; case BO_EQ: return BO_NE; case BO_NE: return BO_EQ; } } static BinaryOperator::Opcode ReverseComparison(BinaryOperator::Opcode op) { switch (op) { default: llvm_unreachable("Invalid opcode."); case BO_LT: return BO_GT; case BO_GT: return BO_LT; case BO_LE: return BO_GE; case BO_GE: return BO_LE; case BO_EQ: case BO_NE: return op; } } SVal SimpleSValBuilder::MakeSymIntVal(const SymExpr *LHS, BinaryOperator::Opcode op, const llvm::APSInt &RHS, QualType resultTy) { bool isIdempotent = false; // Check for a few special cases with known reductions first. switch (op) { default: // We can't reduce this case; just treat it normally. break; case BO_Mul: // a*0 and a*1 if (RHS == 0) return makeIntVal(0, resultTy); else if (RHS == 1) isIdempotent = true; break; case BO_Div: // a/0 and a/1 if (RHS == 0) // This is also handled elsewhere. return UndefinedVal(); else if (RHS == 1) isIdempotent = true; break; case BO_Rem: // a%0 and a%1 if (RHS == 0) // This is also handled elsewhere. return UndefinedVal(); else if (RHS == 1) return makeIntVal(0, resultTy); break; case BO_Add: case BO_Sub: case BO_Shl: case BO_Shr: case BO_Xor: // a+0, a-0, a<<0, a>>0, a^0 if (RHS == 0) isIdempotent = true; break; case BO_And: // a&0 and a&(~0) if (RHS == 0) return makeIntVal(0, resultTy); else if (RHS.isAllOnesValue()) isIdempotent = true; break; case BO_Or: // a|0 and a|(~0) if (RHS == 0) isIdempotent = true; else if (RHS.isAllOnesValue()) { const llvm::APSInt &Result = BasicVals.Convert(resultTy, RHS); return nonloc::ConcreteInt(Result); } break; } // Idempotent ops (like a*1) can still change the type of an expression. // Wrap the LHS up in a NonLoc again and let evalCastFromNonLoc do the // dirty work. if (isIdempotent) return evalCastFromNonLoc(nonloc::SymbolVal(LHS), resultTy); // If we reach this point, the expression cannot be simplified. // Make a SymbolVal for the entire expression. return makeNonLoc(LHS, op, RHS, resultTy); } SVal SimpleSValBuilder::evalBinOpNN(ProgramStateRef state, BinaryOperator::Opcode op, NonLoc lhs, NonLoc rhs, QualType resultTy) { // Handle trivial case where left-side and right-side are the same. if (lhs == rhs) switch (op) { default: break; case BO_EQ: case BO_LE: case BO_GE: return makeTruthVal(true, resultTy); case BO_LT: case BO_GT: case BO_NE: return makeTruthVal(false, resultTy); case BO_Xor: case BO_Sub: return makeIntVal(0, resultTy); case BO_Or: case BO_And: return evalCastFromNonLoc(lhs, resultTy); } while (1) { switch (lhs.getSubKind()) { default: return makeGenericVal(state, op, lhs, rhs, resultTy); case nonloc::LocAsIntegerKind: { Loc lhsL = cast(lhs).getLoc(); switch (rhs.getSubKind()) { case nonloc::LocAsIntegerKind: return evalBinOpLL(state, op, lhsL, cast(rhs).getLoc(), resultTy); case nonloc::ConcreteIntKind: { // Transform the integer into a location and compare. llvm::APSInt i = cast(rhs).getValue(); i.setIsUnsigned(true); i = i.extOrTrunc(Context.getTypeSize(Context.VoidPtrTy)); return evalBinOpLL(state, op, lhsL, makeLoc(i), resultTy); } default: switch (op) { case BO_EQ: return makeTruthVal(false, resultTy); case BO_NE: return makeTruthVal(true, resultTy); default: // This case also handles pointer arithmetic. return makeGenericVal(state, op, lhs, rhs, resultTy); } } } case nonloc::ConcreteIntKind: { const nonloc::ConcreteInt& lhsInt = cast(lhs); // Is the RHS a symbol we can simplify? // FIXME: This was mostly copy/pasted from the LHS-is-a-symbol case. if (const nonloc::SymbolVal *srhs = dyn_cast(&rhs)) { SymbolRef RSym = srhs->getSymbol(); if (RSym->getType(Context)->isIntegerType()) { if (const llvm::APSInt *Constant = state->getSymVal(RSym)) { // The symbol evaluates to a constant. const llvm::APSInt *rhs_I; if (BinaryOperator::isRelationalOp(op)) rhs_I = &BasicVals.Convert(lhsInt.getValue(), *Constant); else rhs_I = &BasicVals.Convert(resultTy, *Constant); rhs = nonloc::ConcreteInt(*rhs_I); } } } if (isa(rhs)) { return lhsInt.evalBinOp(*this, op, cast(rhs)); } else { const llvm::APSInt& lhsValue = lhsInt.getValue(); // Swap the left and right sides and flip the operator if doing so // allows us to better reason about the expression (this is a form // of expression canonicalization). // While we're at it, catch some special cases for non-commutative ops. NonLoc tmp = rhs; rhs = lhs; lhs = tmp; switch (op) { case BO_LT: case BO_GT: case BO_LE: case BO_GE: op = ReverseComparison(op); continue; case BO_EQ: case BO_NE: case BO_Add: case BO_Mul: case BO_And: case BO_Xor: case BO_Or: continue; case BO_Shr: if (lhsValue.isAllOnesValue() && lhsValue.isSigned()) // At this point lhs and rhs have been swapped. return rhs; // FALL-THROUGH case BO_Shl: if (lhsValue == 0) // At this point lhs and rhs have been swapped. return rhs; return makeGenericVal(state, op, rhs, lhs, resultTy); default: return makeGenericVal(state, op, rhs, lhs, resultTy); } } } case nonloc::SymbolValKind: { nonloc::SymbolVal *selhs = cast(&lhs); // LHS is a symbolic expression. if (selhs->isExpression()) { // Only handle LHS of the form "$sym op constant", at least for now. const SymIntExpr *symIntExpr = dyn_cast(selhs->getSymbol()); if (!symIntExpr) return makeGenericVal(state, op, lhs, rhs, resultTy); // Is this a logical not? (!x is represented as x == 0.) if (op == BO_EQ && rhs.isZeroConstant()) { // We know how to negate certain expressions. Simplify them here. BinaryOperator::Opcode opc = symIntExpr->getOpcode(); switch (opc) { default: // We don't know how to negate this operation. // Just handle it as if it were a normal comparison to 0. break; case BO_LAnd: case BO_LOr: llvm_unreachable("Logical operators handled by branching logic."); case BO_Assign: case BO_MulAssign: case BO_DivAssign: case BO_RemAssign: case BO_AddAssign: case BO_SubAssign: case BO_ShlAssign: case BO_ShrAssign: case BO_AndAssign: case BO_XorAssign: case BO_OrAssign: case BO_Comma: llvm_unreachable("'=' and ',' operators handled by ExprEngine."); case BO_PtrMemD: case BO_PtrMemI: llvm_unreachable("Pointer arithmetic not handled here."); case BO_LT: case BO_GT: case BO_LE: case BO_GE: case BO_EQ: case BO_NE: // Negate the comparison and make a value. opc = NegateComparison(opc); assert(symIntExpr->getType(Context) == resultTy); return makeNonLoc(symIntExpr->getLHS(), opc, symIntExpr->getRHS(), resultTy); } } // For now, only handle expressions whose RHS is a constant. const nonloc::ConcreteInt *rhsInt = dyn_cast(&rhs); if (!rhsInt) return makeGenericVal(state, op, lhs, rhs, resultTy); // If both the LHS and the current expression are additive, // fold their constants. if (BinaryOperator::isAdditiveOp(op)) { BinaryOperator::Opcode lop = symIntExpr->getOpcode(); if (BinaryOperator::isAdditiveOp(lop)) { // resultTy may not be the best type to convert to, but it's // probably the best choice in expressions with mixed type // (such as x+1U+2LL). The rules for implicit conversions should // choose a reasonable type to preserve the expression, and will // at least match how the value is going to be used. const llvm::APSInt &first = BasicVals.Convert(resultTy, symIntExpr->getRHS()); const llvm::APSInt &second = BasicVals.Convert(resultTy, rhsInt->getValue()); const llvm::APSInt *newRHS; if (lop == op) newRHS = BasicVals.evalAPSInt(BO_Add, first, second); else newRHS = BasicVals.evalAPSInt(BO_Sub, first, second); return MakeSymIntVal(symIntExpr->getLHS(), lop, *newRHS, resultTy); } } // Otherwise, make a SymbolVal out of the expression. return MakeSymIntVal(symIntExpr, op, rhsInt->getValue(), resultTy); // LHS is a simple symbol (not a symbolic expression). } else { nonloc::SymbolVal *slhs = cast(&lhs); SymbolRef Sym = slhs->getSymbol(); QualType lhsType = Sym->getType(Context); // The conversion type is usually the result type, but not in the case // of relational expressions. QualType conversionType = resultTy; if (BinaryOperator::isRelationalOp(op)) conversionType = lhsType; // Does the symbol simplify to a constant? If so, "fold" the constant // by setting 'lhs' to a ConcreteInt and try again. if (lhsType->isIntegerType()) if (const llvm::APSInt *Constant = state->getSymVal(Sym)) { // The symbol evaluates to a constant. If necessary, promote the // folded constant (LHS) to the result type. const llvm::APSInt &lhs_I = BasicVals.Convert(conversionType, *Constant); lhs = nonloc::ConcreteInt(lhs_I); // Also promote the RHS (if necessary). // For shifts, it is not necessary to promote the RHS. if (BinaryOperator::isShiftOp(op)) continue; // Other operators: do an implicit conversion. This shouldn't be // necessary once we support truncation/extension of symbolic values. if (nonloc::ConcreteInt *rhs_I = dyn_cast(&rhs)){ rhs = nonloc::ConcreteInt(BasicVals.Convert(conversionType, rhs_I->getValue())); } continue; } // Is the RHS a symbol we can simplify? if (const nonloc::SymbolVal *srhs = dyn_cast(&rhs)) { SymbolRef RSym = srhs->getSymbol(); if (RSym->getType(Context)->isIntegerType()) { if (const llvm::APSInt *Constant = state->getSymVal(RSym)) { // The symbol evaluates to a constant. const llvm::APSInt &rhs_I = BasicVals.Convert(conversionType, *Constant); rhs = nonloc::ConcreteInt(rhs_I); } } } if (isa(rhs)) { return MakeSymIntVal(slhs->getSymbol(), op, cast(rhs).getValue(), resultTy); } return makeGenericVal(state, op, lhs, rhs, resultTy); } } } } } // FIXME: all this logic will change if/when we have MemRegion::getLocation(). SVal SimpleSValBuilder::evalBinOpLL(ProgramStateRef state, BinaryOperator::Opcode op, Loc lhs, Loc rhs, QualType resultTy) { // Only comparisons and subtractions are valid operations on two pointers. // See [C99 6.5.5 through 6.5.14] or [C++0x 5.6 through 5.15]. // However, if a pointer is casted to an integer, evalBinOpNN may end up // calling this function with another operation (PR7527). We don't attempt to // model this for now, but it could be useful, particularly when the // "location" is actually an integer value that's been passed through a void*. if (!(BinaryOperator::isComparisonOp(op) || op == BO_Sub)) return UnknownVal(); // Special cases for when both sides are identical. if (lhs == rhs) { switch (op) { default: llvm_unreachable("Unimplemented operation for two identical values"); case BO_Sub: return makeZeroVal(resultTy); case BO_EQ: case BO_LE: case BO_GE: return makeTruthVal(true, resultTy); case BO_NE: case BO_LT: case BO_GT: return makeTruthVal(false, resultTy); } } switch (lhs.getSubKind()) { default: llvm_unreachable("Ordering not implemented for this Loc."); case loc::GotoLabelKind: // The only thing we know about labels is that they're non-null. if (rhs.isZeroConstant()) { switch (op) { default: break; case BO_Sub: return evalCastFromLoc(lhs, resultTy); case BO_EQ: case BO_LE: case BO_LT: return makeTruthVal(false, resultTy); case BO_NE: case BO_GT: case BO_GE: return makeTruthVal(true, resultTy); } } // There may be two labels for the same location, and a function region may // have the same address as a label at the start of the function (depending // on the ABI). // FIXME: we can probably do a comparison against other MemRegions, though. // FIXME: is there a way to tell if two labels refer to the same location? return UnknownVal(); case loc::ConcreteIntKind: { // If one of the operands is a symbol and the other is a constant, // build an expression for use by the constraint manager. if (SymbolRef rSym = rhs.getAsLocSymbol()) { // We can only build expressions with symbols on the left, // so we need a reversible operator. if (!BinaryOperator::isComparisonOp(op)) return UnknownVal(); const llvm::APSInt &lVal = cast(lhs).getValue(); return makeNonLoc(rSym, ReverseComparison(op), lVal, resultTy); } // If both operands are constants, just perform the operation. if (loc::ConcreteInt *rInt = dyn_cast(&rhs)) { SVal ResultVal = cast(lhs).evalBinOp(BasicVals, op, *rInt); if (Loc *Result = dyn_cast(&ResultVal)) return evalCastFromLoc(*Result, resultTy); else return UnknownVal(); } // Special case comparisons against NULL. // This must come after the test if the RHS is a symbol, which is used to // build constraints. The address of any non-symbolic region is guaranteed // to be non-NULL, as is any label. assert(isa(rhs) || isa(rhs)); if (lhs.isZeroConstant()) { switch (op) { default: break; case BO_EQ: case BO_GT: case BO_GE: return makeTruthVal(false, resultTy); case BO_NE: case BO_LT: case BO_LE: return makeTruthVal(true, resultTy); } } // Comparing an arbitrary integer to a region or label address is // completely unknowable. return UnknownVal(); } case loc::MemRegionKind: { if (loc::ConcreteInt *rInt = dyn_cast(&rhs)) { // If one of the operands is a symbol and the other is a constant, // build an expression for use by the constraint manager. if (SymbolRef lSym = lhs.getAsLocSymbol()) return MakeSymIntVal(lSym, op, rInt->getValue(), resultTy); // Special case comparisons to NULL. // This must come after the test if the LHS is a symbol, which is used to // build constraints. The address of any non-symbolic region is guaranteed // to be non-NULL. if (rInt->isZeroConstant()) { switch (op) { default: break; case BO_Sub: return evalCastFromLoc(lhs, resultTy); case BO_EQ: case BO_LT: case BO_LE: return makeTruthVal(false, resultTy); case BO_NE: case BO_GT: case BO_GE: return makeTruthVal(true, resultTy); } } // Comparing a region to an arbitrary integer is completely unknowable. return UnknownVal(); } // Get both values as regions, if possible. const MemRegion *LeftMR = lhs.getAsRegion(); assert(LeftMR && "MemRegionKind SVal doesn't have a region!"); const MemRegion *RightMR = rhs.getAsRegion(); if (!RightMR) // The RHS is probably a label, which in theory could address a region. // FIXME: we can probably make a more useful statement about non-code // regions, though. return UnknownVal(); // If both values wrap regions, see if they're from different base regions. const MemRegion *LeftBase = LeftMR->getBaseRegion(); const MemRegion *RightBase = RightMR->getBaseRegion(); if (LeftBase != RightBase && !isa(LeftBase) && !isa(RightBase)) { switch (op) { default: return UnknownVal(); case BO_EQ: return makeTruthVal(false, resultTy); case BO_NE: return makeTruthVal(true, resultTy); } } // The two regions are from the same base region. See if they're both a // type of region we know how to compare. const MemSpaceRegion *LeftMS = LeftBase->getMemorySpace(); const MemSpaceRegion *RightMS = RightBase->getMemorySpace(); // Heuristic: assume that no symbolic region (whose memory space is // unknown) is on the stack. // FIXME: we should be able to be more precise once we can do better // aliasing constraints for symbolic regions, but this is a reasonable, // albeit unsound, assumption that holds most of the time. if (isa(LeftMS) ^ isa(RightMS)) { switch (op) { default: break; case BO_EQ: return makeTruthVal(false, resultTy); case BO_NE: return makeTruthVal(true, resultTy); } } // FIXME: If/when there is a getAsRawOffset() for FieldRegions, this // ElementRegion path and the FieldRegion path below should be unified. if (const ElementRegion *LeftER = dyn_cast(LeftMR)) { // First see if the right region is also an ElementRegion. const ElementRegion *RightER = dyn_cast(RightMR); if (!RightER) return UnknownVal(); // Next, see if the two ERs have the same super-region and matching types. // FIXME: This should do something useful even if the types don't match, // though if both indexes are constant the RegionRawOffset path will // give the correct answer. if (LeftER->getSuperRegion() == RightER->getSuperRegion() && LeftER->getElementType() == RightER->getElementType()) { // Get the left index and cast it to the correct type. // If the index is unknown or undefined, bail out here. SVal LeftIndexVal = LeftER->getIndex(); NonLoc *LeftIndex = dyn_cast(&LeftIndexVal); if (!LeftIndex) return UnknownVal(); LeftIndexVal = evalCastFromNonLoc(*LeftIndex, resultTy); LeftIndex = dyn_cast(&LeftIndexVal); if (!LeftIndex) return UnknownVal(); // Do the same for the right index. SVal RightIndexVal = RightER->getIndex(); NonLoc *RightIndex = dyn_cast(&RightIndexVal); if (!RightIndex) return UnknownVal(); RightIndexVal = evalCastFromNonLoc(*RightIndex, resultTy); RightIndex = dyn_cast(&RightIndexVal); if (!RightIndex) return UnknownVal(); // Actually perform the operation. // evalBinOpNN expects the two indexes to already be the right type. return evalBinOpNN(state, op, *LeftIndex, *RightIndex, resultTy); } // If the element indexes aren't comparable, see if the raw offsets are. RegionRawOffset LeftOffset = LeftER->getAsArrayOffset(); RegionRawOffset RightOffset = RightER->getAsArrayOffset(); if (LeftOffset.getRegion() != NULL && LeftOffset.getRegion() == RightOffset.getRegion()) { CharUnits left = LeftOffset.getOffset(); CharUnits right = RightOffset.getOffset(); switch (op) { default: return UnknownVal(); case BO_LT: return makeTruthVal(left < right, resultTy); case BO_GT: return makeTruthVal(left > right, resultTy); case BO_LE: return makeTruthVal(left <= right, resultTy); case BO_GE: return makeTruthVal(left >= right, resultTy); case BO_EQ: return makeTruthVal(left == right, resultTy); case BO_NE: return makeTruthVal(left != right, resultTy); } } // If we get here, we have no way of comparing the ElementRegions. return UnknownVal(); } // See if both regions are fields of the same structure. // FIXME: This doesn't handle nesting, inheritance, or Objective-C ivars. if (const FieldRegion *LeftFR = dyn_cast(LeftMR)) { // Only comparisons are meaningful here! if (!BinaryOperator::isComparisonOp(op)) return UnknownVal(); // First see if the right region is also a FieldRegion. const FieldRegion *RightFR = dyn_cast(RightMR); if (!RightFR) return UnknownVal(); // Next, see if the two FRs have the same super-region. // FIXME: This doesn't handle casts yet, and simply stripping the casts // doesn't help. if (LeftFR->getSuperRegion() != RightFR->getSuperRegion()) return UnknownVal(); const FieldDecl *LeftFD = LeftFR->getDecl(); const FieldDecl *RightFD = RightFR->getDecl(); const RecordDecl *RD = LeftFD->getParent(); // Make sure the two FRs are from the same kind of record. Just in case! // FIXME: This is probably where inheritance would be a problem. if (RD != RightFD->getParent()) return UnknownVal(); // We know for sure that the two fields are not the same, since that // would have given us the same SVal. if (op == BO_EQ) return makeTruthVal(false, resultTy); if (op == BO_NE) return makeTruthVal(true, resultTy); // Iterate through the fields and see which one comes first. // [C99 6.7.2.1.13] "Within a structure object, the non-bit-field // members and the units in which bit-fields reside have addresses that // increase in the order in which they are declared." bool leftFirst = (op == BO_LT || op == BO_LE); for (RecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end(); I!=E; ++I) { if (*I == LeftFD) return makeTruthVal(leftFirst, resultTy); if (*I == RightFD) return makeTruthVal(!leftFirst, resultTy); } llvm_unreachable("Fields not found in parent record's definition"); } // If we get here, we have no way of comparing the regions. return UnknownVal(); } } } SVal SimpleSValBuilder::evalBinOpLN(ProgramStateRef state, BinaryOperator::Opcode op, Loc lhs, NonLoc rhs, QualType resultTy) { // Special case: rhs is a zero constant. if (rhs.isZeroConstant()) return lhs; // Special case: 'rhs' is an integer that has the same width as a pointer and // we are using the integer location in a comparison. Normally this cannot be // triggered, but transfer functions like those for OSCommpareAndSwapBarrier32 // can generate comparisons that trigger this code. // FIXME: Are all locations guaranteed to have pointer width? if (BinaryOperator::isComparisonOp(op)) { if (nonloc::ConcreteInt *rhsInt = dyn_cast(&rhs)) { const llvm::APSInt *x = &rhsInt->getValue(); ASTContext &ctx = Context; if (ctx.getTypeSize(ctx.VoidPtrTy) == x->getBitWidth()) { // Convert the signedness of the integer (if necessary). if (x->isSigned()) x = &getBasicValueFactory().getValue(*x, true); return evalBinOpLL(state, op, lhs, loc::ConcreteInt(*x), resultTy); } } } // We are dealing with pointer arithmetic. // Handle pointer arithmetic on constant values. if (nonloc::ConcreteInt *rhsInt = dyn_cast(&rhs)) { if (loc::ConcreteInt *lhsInt = dyn_cast(&lhs)) { const llvm::APSInt &leftI = lhsInt->getValue(); assert(leftI.isUnsigned()); llvm::APSInt rightI(rhsInt->getValue(), /* isUnsigned */ true); // Convert the bitwidth of rightI. This should deal with overflow // since we are dealing with concrete values. rightI = rightI.extOrTrunc(leftI.getBitWidth()); // Offset the increment by the pointer size. llvm::APSInt Multiplicand(rightI.getBitWidth(), /* isUnsigned */ true); rightI *= Multiplicand; // Compute the adjusted pointer. switch (op) { case BO_Add: rightI = leftI + rightI; break; case BO_Sub: rightI = leftI - rightI; break; default: llvm_unreachable("Invalid pointer arithmetic operation"); } return loc::ConcreteInt(getBasicValueFactory().getValue(rightI)); } } // Handle cases where 'lhs' is a region. if (const MemRegion *region = lhs.getAsRegion()) { rhs = cast(convertToArrayIndex(rhs)); SVal index = UnknownVal(); const MemRegion *superR = 0; QualType elementType; if (const ElementRegion *elemReg = dyn_cast(region)) { assert(op == BO_Add || op == BO_Sub); index = evalBinOpNN(state, op, elemReg->getIndex(), rhs, getArrayIndexType()); superR = elemReg->getSuperRegion(); elementType = elemReg->getElementType(); } else if (isa(region)) { superR = region; index = rhs; if (const PointerType *PT = resultTy->getAs()) { elementType = PT->getPointeeType(); } else { const ObjCObjectPointerType *OT = resultTy->getAs(); elementType = OT->getPointeeType(); } } if (NonLoc *indexV = dyn_cast(&index)) { return loc::MemRegionVal(MemMgr.getElementRegion(elementType, *indexV, superR, getContext())); } } return UnknownVal(); } const llvm::APSInt *SimpleSValBuilder::getKnownValue(ProgramStateRef state, SVal V) { if (V.isUnknownOrUndef()) return NULL; if (loc::ConcreteInt* X = dyn_cast(&V)) return &X->getValue(); if (nonloc::ConcreteInt* X = dyn_cast(&V)) return &X->getValue(); if (SymbolRef Sym = V.getAsSymbol()) return state->getSymVal(Sym); // FIXME: Add support for SymExprs. return NULL; }