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Diffstat (limited to 'clang/lib/StaticAnalyzer/Checkers/IteratorModeling.cpp')
| -rw-r--r-- | clang/lib/StaticAnalyzer/Checkers/IteratorModeling.cpp | 1574 |
1 files changed, 1574 insertions, 0 deletions
diff --git a/clang/lib/StaticAnalyzer/Checkers/IteratorModeling.cpp b/clang/lib/StaticAnalyzer/Checkers/IteratorModeling.cpp new file mode 100644 index 00000000000..9730de0e4cd --- /dev/null +++ b/clang/lib/StaticAnalyzer/Checkers/IteratorModeling.cpp @@ -0,0 +1,1574 @@ +//===-- IteratorModeling.cpp --------------------------------------*- C++ -*--// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// Defines a checker for using iterators outside their range (past end). Usage +// means here dereferencing, incrementing etc. +// +//===----------------------------------------------------------------------===// +// +// In the code, iterator can be represented as a: +// * type-I: typedef-ed pointer. Operations over such iterator, such as +// comparisons or increments, are modeled straightforwardly by the +// analyzer. +// * type-II: structure with its method bodies available. Operations over such +// iterator are inlined by the analyzer, and results of modeling +// these operations are exposing implementation details of the +// iterators, which is not necessarily helping. +// * type-III: completely opaque structure. Operations over such iterator are +// modeled conservatively, producing conjured symbols everywhere. +// +// To handle all these types in a common way we introduce a structure called +// IteratorPosition which is an abstraction of the position the iterator +// represents using symbolic expressions. The checker handles all the +// operations on this structure. +// +// Additionally, depending on the circumstances, operators of types II and III +// can be represented as: +// * type-IIa, type-IIIa: conjured structure symbols - when returned by value +// from conservatively evaluated methods such as +// `.begin()`. +// * type-IIb, type-IIIb: memory regions of iterator-typed objects, such as +// variables or temporaries, when the iterator object is +// currently treated as an lvalue. +// * type-IIc, type-IIIc: compound values of iterator-typed objects, when the +// iterator object is treated as an rvalue taken of a +// particular lvalue, eg. a copy of "type-a" iterator +// object, or an iterator that existed before the +// analysis has started. +// +// To handle any of these three different representations stored in an SVal we +// use setter and getters functions which separate the three cases. To store +// them we use a pointer union of symbol and memory region. +// +// The checker works the following way: We record the begin and the +// past-end iterator for all containers whenever their `.begin()` and `.end()` +// are called. Since the Constraint Manager cannot handle such SVals we need +// to take over its role. We post-check equality and non-equality comparisons +// and record that the two sides are equal if we are in the 'equal' branch +// (true-branch for `==` and false-branch for `!=`). +// +// In case of type-I or type-II iterators we get a concrete integer as a result +// of the comparison (1 or 0) but in case of type-III we only get a Symbol. In +// this latter case we record the symbol and reload it in evalAssume() and do +// the propagation there. We also handle (maybe double) negated comparisons +// which are represented in the form of (x == 0 or x != 0) where x is the +// comparison itself. +// +// Since `SimpleConstraintManager` cannot handle complex symbolic expressions +// we only use expressions of the format S, S+n or S-n for iterator positions +// where S is a conjured symbol and n is an unsigned concrete integer. When +// making an assumption e.g. `S1 + n == S2 + m` we store `S1 - S2 == m - n` as +// a constraint which we later retrieve when doing an actual comparison. + +#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h" +#include "clang/AST/DeclTemplate.h" +#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h" +#include "clang/StaticAnalyzer/Core/Checker.h" +#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h" +#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" +#include "clang/StaticAnalyzer/Core/PathSensitive/DynamicType.h" + +#include "Iterator.h" + +#include <utility> + +using namespace clang; +using namespace ento; +using namespace iterator; + +namespace { + +class IteratorModeling + : public Checker<check::PostCall, check::PostStmt<MaterializeTemporaryExpr>, + check::Bind, check::LiveSymbols, check::DeadSymbols> { + + void handleComparison(CheckerContext &C, const Expr *CE, const SVal &RetVal, + const SVal &LVal, const SVal &RVal, + OverloadedOperatorKind Op) const; + void processComparison(CheckerContext &C, ProgramStateRef State, + SymbolRef Sym1, SymbolRef Sym2, const SVal &RetVal, + OverloadedOperatorKind Op) const; + void handleIncrement(CheckerContext &C, const SVal &RetVal, const SVal &Iter, + bool Postfix) const; + void handleDecrement(CheckerContext &C, const SVal &RetVal, const SVal &Iter, + bool Postfix) const; + void handleRandomIncrOrDecr(CheckerContext &C, const Expr *CE, + OverloadedOperatorKind Op, const SVal &RetVal, + const SVal &LHS, const SVal &RHS) const; + void handleBegin(CheckerContext &C, const Expr *CE, const SVal &RetVal, + const SVal &Cont) const; + void handleEnd(CheckerContext &C, const Expr *CE, const SVal &RetVal, + const SVal &Cont) const; + void assignToContainer(CheckerContext &C, const Expr *CE, const SVal &RetVal, + const MemRegion *Cont) const; + void handleAssign(CheckerContext &C, const SVal &Cont, + const Expr *CE = nullptr, + const SVal &OldCont = UndefinedVal()) const; + void handleClear(CheckerContext &C, const SVal &Cont) const; + void handlePushBack(CheckerContext &C, const SVal &Cont) const; + void handlePopBack(CheckerContext &C, const SVal &Cont) const; + void handlePushFront(CheckerContext &C, const SVal &Cont) const; + void handlePopFront(CheckerContext &C, const SVal &Cont) const; + void handleInsert(CheckerContext &C, const SVal &Iter) const; + void handleErase(CheckerContext &C, const SVal &Iter) const; + void handleErase(CheckerContext &C, const SVal &Iter1, + const SVal &Iter2) const; + void handleEraseAfter(CheckerContext &C, const SVal &Iter) const; + void handleEraseAfter(CheckerContext &C, const SVal &Iter1, + const SVal &Iter2) const; +public: + IteratorModeling() {} + + void checkPostCall(const CallEvent &Call, CheckerContext &C) const; + void checkBind(SVal Loc, SVal Val, const Stmt *S, CheckerContext &C) const; + void checkPostStmt(const CXXConstructExpr *CCE, CheckerContext &C) const; + void checkPostStmt(const DeclStmt *DS, CheckerContext &C) const; + void checkPostStmt(const MaterializeTemporaryExpr *MTE, + CheckerContext &C) const; + void checkLiveSymbols(ProgramStateRef State, SymbolReaper &SR) const; + void checkDeadSymbols(SymbolReaper &SR, CheckerContext &C) const; +}; + +bool isBeginCall(const FunctionDecl *Func); +bool isEndCall(const FunctionDecl *Func); +bool isAssignCall(const FunctionDecl *Func); +bool isClearCall(const FunctionDecl *Func); +bool isPushBackCall(const FunctionDecl *Func); +bool isEmplaceBackCall(const FunctionDecl *Func); +bool isPopBackCall(const FunctionDecl *Func); +bool isPushFrontCall(const FunctionDecl *Func); +bool isEmplaceFrontCall(const FunctionDecl *Func); +bool isPopFrontCall(const FunctionDecl *Func); +bool isAssignmentOperator(OverloadedOperatorKind OK); +bool isSimpleComparisonOperator(OverloadedOperatorKind OK); +bool hasSubscriptOperator(ProgramStateRef State, const MemRegion *Reg); +bool frontModifiable(ProgramStateRef State, const MemRegion *Reg); +bool backModifiable(ProgramStateRef State, const MemRegion *Reg); +SymbolRef getContainerBegin(ProgramStateRef State, const MemRegion *Cont); +SymbolRef getContainerEnd(ProgramStateRef State, const MemRegion *Cont); +ProgramStateRef createContainerBegin(ProgramStateRef State, + const MemRegion *Cont, const Expr *E, + QualType T, const LocationContext *LCtx, + unsigned BlockCount); +ProgramStateRef createContainerEnd(ProgramStateRef State, const MemRegion *Cont, + const Expr *E, QualType T, + const LocationContext *LCtx, + unsigned BlockCount); +ProgramStateRef setContainerData(ProgramStateRef State, const MemRegion *Cont, + const ContainerData &CData); +ProgramStateRef removeIteratorPosition(ProgramStateRef State, const SVal &Val); +ProgramStateRef assumeNoOverflow(ProgramStateRef State, SymbolRef Sym, + long Scale); +ProgramStateRef invalidateAllIteratorPositions(ProgramStateRef State, + const MemRegion *Cont); +ProgramStateRef +invalidateAllIteratorPositionsExcept(ProgramStateRef State, + const MemRegion *Cont, SymbolRef Offset, + BinaryOperator::Opcode Opc); +ProgramStateRef invalidateIteratorPositions(ProgramStateRef State, + SymbolRef Offset, + BinaryOperator::Opcode Opc); +ProgramStateRef invalidateIteratorPositions(ProgramStateRef State, + SymbolRef Offset1, + BinaryOperator::Opcode Opc1, + SymbolRef Offset2, + BinaryOperator::Opcode Opc2); +ProgramStateRef reassignAllIteratorPositions(ProgramStateRef State, + const MemRegion *Cont, + const MemRegion *NewCont); +ProgramStateRef reassignAllIteratorPositionsUnless(ProgramStateRef State, + const MemRegion *Cont, + const MemRegion *NewCont, + SymbolRef Offset, + BinaryOperator::Opcode Opc); +ProgramStateRef rebaseSymbolInIteratorPositionsIf( + ProgramStateRef State, SValBuilder &SVB, SymbolRef OldSym, + SymbolRef NewSym, SymbolRef CondSym, BinaryOperator::Opcode Opc); +ProgramStateRef relateSymbols(ProgramStateRef State, SymbolRef Sym1, + SymbolRef Sym2, bool Equal); +SymbolRef rebaseSymbol(ProgramStateRef State, SValBuilder &SVB, SymbolRef Expr, + SymbolRef OldSym, SymbolRef NewSym); +bool hasLiveIterators(ProgramStateRef State, const MemRegion *Cont); +bool isBoundThroughLazyCompoundVal(const Environment &Env, + const MemRegion *Reg); + +} // namespace + +void IteratorModeling::checkPostCall(const CallEvent &Call, + CheckerContext &C) const { + // Record new iterator positions and iterator position changes + const auto *Func = dyn_cast_or_null<FunctionDecl>(Call.getDecl()); + if (!Func) + return; + + if (Func->isOverloadedOperator()) { + const auto Op = Func->getOverloadedOperator(); + if (isAssignmentOperator(Op)) { + // Overloaded 'operator=' must be a non-static member function. + const auto *InstCall = cast<CXXInstanceCall>(&Call); + if (cast<CXXMethodDecl>(Func)->isMoveAssignmentOperator()) { + handleAssign(C, InstCall->getCXXThisVal(), Call.getOriginExpr(), + Call.getArgSVal(0)); + return; + } + + handleAssign(C, InstCall->getCXXThisVal()); + return; + } else if (isSimpleComparisonOperator(Op)) { + const auto *OrigExpr = Call.getOriginExpr(); + if (!OrigExpr) + return; + + if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) { + handleComparison(C, OrigExpr, Call.getReturnValue(), + InstCall->getCXXThisVal(), Call.getArgSVal(0), Op); + return; + } + + handleComparison(C, OrigExpr, Call.getReturnValue(), Call.getArgSVal(0), + Call.getArgSVal(1), Op); + return; + } else if (isRandomIncrOrDecrOperator(Func->getOverloadedOperator())) { + const auto *OrigExpr = Call.getOriginExpr(); + if (!OrigExpr) + return; + + if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) { + if (Call.getNumArgs() >= 1 && + Call.getArgExpr(0)->getType()->isIntegralOrEnumerationType()) { + handleRandomIncrOrDecr(C, OrigExpr, Func->getOverloadedOperator(), + Call.getReturnValue(), + InstCall->getCXXThisVal(), Call.getArgSVal(0)); + return; + } + } else { + if (Call.getNumArgs() >= 2 && + Call.getArgExpr(1)->getType()->isIntegralOrEnumerationType()) { + handleRandomIncrOrDecr(C, OrigExpr, Func->getOverloadedOperator(), + Call.getReturnValue(), Call.getArgSVal(0), + Call.getArgSVal(1)); + return; + } + } + } else if (isIncrementOperator(Func->getOverloadedOperator())) { + if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) { + handleIncrement(C, Call.getReturnValue(), InstCall->getCXXThisVal(), + Call.getNumArgs()); + return; + } + + handleIncrement(C, Call.getReturnValue(), Call.getArgSVal(0), + Call.getNumArgs()); + return; + } else if (isDecrementOperator(Func->getOverloadedOperator())) { + if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) { + handleDecrement(C, Call.getReturnValue(), InstCall->getCXXThisVal(), + Call.getNumArgs()); + return; + } + + handleDecrement(C, Call.getReturnValue(), Call.getArgSVal(0), + Call.getNumArgs()); + return; + } + } else { + if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) { + if (isAssignCall(Func)) { + handleAssign(C, InstCall->getCXXThisVal()); + return; + } + + if (isClearCall(Func)) { + handleClear(C, InstCall->getCXXThisVal()); + return; + } + + if (isPushBackCall(Func) || isEmplaceBackCall(Func)) { + handlePushBack(C, InstCall->getCXXThisVal()); + return; + } + + if (isPopBackCall(Func)) { + handlePopBack(C, InstCall->getCXXThisVal()); + return; + } + + if (isPushFrontCall(Func) || isEmplaceFrontCall(Func)) { + handlePushFront(C, InstCall->getCXXThisVal()); + return; + } + + if (isPopFrontCall(Func)) { + handlePopFront(C, InstCall->getCXXThisVal()); + return; + } + + if (isInsertCall(Func) || isEmplaceCall(Func)) { + handleInsert(C, Call.getArgSVal(0)); + return; + } + + if (isEraseCall(Func)) { + if (Call.getNumArgs() == 1) { + handleErase(C, Call.getArgSVal(0)); + return; + } + + if (Call.getNumArgs() == 2) { + handleErase(C, Call.getArgSVal(0), Call.getArgSVal(1)); + return; + } + } + + if (isEraseAfterCall(Func)) { + if (Call.getNumArgs() == 1) { + handleEraseAfter(C, Call.getArgSVal(0)); + return; + } + + if (Call.getNumArgs() == 2) { + handleEraseAfter(C, Call.getArgSVal(0), Call.getArgSVal(1)); + return; + } + } + } + + const auto *OrigExpr = Call.getOriginExpr(); + if (!OrigExpr) + return; + + if (!isIteratorType(Call.getResultType())) + return; + + auto State = C.getState(); + + if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) { + if (isBeginCall(Func)) { + handleBegin(C, OrigExpr, Call.getReturnValue(), + InstCall->getCXXThisVal()); + return; + } + + if (isEndCall(Func)) { + handleEnd(C, OrigExpr, Call.getReturnValue(), + InstCall->getCXXThisVal()); + return; + } + } + + // Already bound to container? + if (getIteratorPosition(State, Call.getReturnValue())) + return; + + // Copy-like and move constructors + if (isa<CXXConstructorCall>(&Call) && Call.getNumArgs() == 1) { + if (const auto *Pos = getIteratorPosition(State, Call.getArgSVal(0))) { + State = setIteratorPosition(State, Call.getReturnValue(), *Pos); + if (cast<CXXConstructorDecl>(Func)->isMoveConstructor()) { + State = removeIteratorPosition(State, Call.getArgSVal(0)); + } + C.addTransition(State); + return; + } + } + + // Assumption: if return value is an iterator which is not yet bound to a + // container, then look for the first iterator argument, and + // bind the return value to the same container. This approach + // works for STL algorithms. + // FIXME: Add a more conservative mode + for (unsigned i = 0; i < Call.getNumArgs(); ++i) { + if (isIteratorType(Call.getArgExpr(i)->getType())) { + if (const auto *Pos = getIteratorPosition(State, Call.getArgSVal(i))) { + assignToContainer(C, OrigExpr, Call.getReturnValue(), + Pos->getContainer()); + return; + } + } + } + } +} + +void IteratorModeling::checkBind(SVal Loc, SVal Val, const Stmt *S, + CheckerContext &C) const { + auto State = C.getState(); + const auto *Pos = getIteratorPosition(State, Val); + if (Pos) { + State = setIteratorPosition(State, Loc, *Pos); + C.addTransition(State); + } else { + const auto *OldPos = getIteratorPosition(State, Loc); + if (OldPos) { + State = removeIteratorPosition(State, Loc); + C.addTransition(State); + } + } +} + +void IteratorModeling::checkPostStmt(const MaterializeTemporaryExpr *MTE, + CheckerContext &C) const { + /* Transfer iterator state to temporary objects */ + auto State = C.getState(); + const auto *Pos = getIteratorPosition(State, C.getSVal(MTE->getSubExpr())); + if (!Pos) + return; + State = setIteratorPosition(State, C.getSVal(MTE), *Pos); + C.addTransition(State); +} + +void IteratorModeling::checkLiveSymbols(ProgramStateRef State, + SymbolReaper &SR) const { + // Keep symbolic expressions of iterator positions, container begins and ends + // alive + auto RegionMap = State->get<IteratorRegionMap>(); + for (const auto Reg : RegionMap) { + const auto Offset = Reg.second.getOffset(); + for (auto i = Offset->symbol_begin(); i != Offset->symbol_end(); ++i) + if (isa<SymbolData>(*i)) + SR.markLive(*i); + } + + auto SymbolMap = State->get<IteratorSymbolMap>(); + for (const auto Sym : SymbolMap) { + const auto Offset = Sym.second.getOffset(); + for (auto i = Offset->symbol_begin(); i != Offset->symbol_end(); ++i) + if (isa<SymbolData>(*i)) + SR.markLive(*i); + } + + auto ContMap = State->get<ContainerMap>(); + for (const auto Cont : ContMap) { + const auto CData = Cont.second; + if (CData.getBegin()) { + SR.markLive(CData.getBegin()); + if(const auto *SIE = dyn_cast<SymIntExpr>(CData.getBegin())) + SR.markLive(SIE->getLHS()); + } + if (CData.getEnd()) { + SR.markLive(CData.getEnd()); + if(const auto *SIE = dyn_cast<SymIntExpr>(CData.getEnd())) + SR.markLive(SIE->getLHS()); + } + } +} + +void IteratorModeling::checkDeadSymbols(SymbolReaper &SR, + CheckerContext &C) const { + // Cleanup + auto State = C.getState(); + + auto RegionMap = State->get<IteratorRegionMap>(); + for (const auto Reg : RegionMap) { + if (!SR.isLiveRegion(Reg.first)) { + // The region behind the `LazyCompoundVal` is often cleaned up before + // the `LazyCompoundVal` itself. If there are iterator positions keyed + // by these regions their cleanup must be deferred. + if (!isBoundThroughLazyCompoundVal(State->getEnvironment(), Reg.first)) { + State = State->remove<IteratorRegionMap>(Reg.first); + } + } + } + + auto SymbolMap = State->get<IteratorSymbolMap>(); + for (const auto Sym : SymbolMap) { + if (!SR.isLive(Sym.first)) { + State = State->remove<IteratorSymbolMap>(Sym.first); + } + } + + auto ContMap = State->get<ContainerMap>(); + for (const auto Cont : ContMap) { + if (!SR.isLiveRegion(Cont.first)) { + // We must keep the container data while it has live iterators to be able + // to compare them to the begin and the end of the container. + if (!hasLiveIterators(State, Cont.first)) { + State = State->remove<ContainerMap>(Cont.first); + } + } + } + + C.addTransition(State); +} + +void IteratorModeling::handleComparison(CheckerContext &C, const Expr *CE, + const SVal &RetVal, const SVal &LVal, + const SVal &RVal, + OverloadedOperatorKind Op) const { + // Record the operands and the operator of the comparison for the next + // evalAssume, if the result is a symbolic expression. If it is a concrete + // value (only one branch is possible), then transfer the state between + // the operands according to the operator and the result + auto State = C.getState(); + const auto *LPos = getIteratorPosition(State, LVal); + const auto *RPos = getIteratorPosition(State, RVal); + const MemRegion *Cont = nullptr; + if (LPos) { + Cont = LPos->getContainer(); + } else if (RPos) { + Cont = RPos->getContainer(); + } + if (!Cont) + return; + + // At least one of the iterators have recorded positions. If one of them has + // not then create a new symbol for the offset. + SymbolRef Sym; + if (!LPos || !RPos) { + auto &SymMgr = C.getSymbolManager(); + Sym = SymMgr.conjureSymbol(CE, C.getLocationContext(), + C.getASTContext().LongTy, C.blockCount()); + State = assumeNoOverflow(State, Sym, 4); + } + + if (!LPos) { + State = setIteratorPosition(State, LVal, + IteratorPosition::getPosition(Cont, Sym)); + LPos = getIteratorPosition(State, LVal); + } else if (!RPos) { + State = setIteratorPosition(State, RVal, + IteratorPosition::getPosition(Cont, Sym)); + RPos = getIteratorPosition(State, RVal); + } + + processComparison(C, State, LPos->getOffset(), RPos->getOffset(), RetVal, Op); +} + +void IteratorModeling::processComparison(CheckerContext &C, + ProgramStateRef State, SymbolRef Sym1, + SymbolRef Sym2, const SVal &RetVal, + OverloadedOperatorKind Op) const { + if (const auto TruthVal = RetVal.getAs<nonloc::ConcreteInt>()) { + if ((State = relateSymbols(State, Sym1, Sym2, + (Op == OO_EqualEqual) == + (TruthVal->getValue() != 0)))) { + C.addTransition(State); + } else { + C.generateSink(State, C.getPredecessor()); + } + return; + } + + const auto ConditionVal = RetVal.getAs<DefinedSVal>(); + if (!ConditionVal) + return; + + if (auto StateTrue = relateSymbols(State, Sym1, Sym2, Op == OO_EqualEqual)) { + StateTrue = StateTrue->assume(*ConditionVal, true); + C.addTransition(StateTrue); + } + + if (auto StateFalse = relateSymbols(State, Sym1, Sym2, Op != OO_EqualEqual)) { + StateFalse = StateFalse->assume(*ConditionVal, false); + C.addTransition(StateFalse); + } +} + +void IteratorModeling::handleIncrement(CheckerContext &C, const SVal &RetVal, + const SVal &Iter, bool Postfix) const { + // Increment the symbolic expressions which represents the position of the + // iterator + auto State = C.getState(); + auto &BVF = C.getSymbolManager().getBasicVals(); + + const auto *Pos = getIteratorPosition(State, Iter); + if (!Pos) + return; + + auto NewState = + advancePosition(State, Iter, OO_Plus, + nonloc::ConcreteInt(BVF.getValue(llvm::APSInt::get(1)))); + assert(NewState && + "Advancing position by concrete int should always be successful"); + + const auto *NewPos = getIteratorPosition(NewState, Iter); + assert(NewPos && + "Iterator should have position after successful advancement"); + + State = setIteratorPosition(State, Iter, *NewPos); + State = setIteratorPosition(State, RetVal, Postfix ? *Pos : *NewPos); + C.addTransition(State); +} + +void IteratorModeling::handleDecrement(CheckerContext &C, const SVal &RetVal, + const SVal &Iter, bool Postfix) const { + // Decrement the symbolic expressions which represents the position of the + // iterator + auto State = C.getState(); + auto &BVF = C.getSymbolManager().getBasicVals(); + + const auto *Pos = getIteratorPosition(State, Iter); + if (!Pos) + return; + + auto NewState = + advancePosition(State, Iter, OO_Minus, + nonloc::ConcreteInt(BVF.getValue(llvm::APSInt::get(1)))); + assert(NewState && + "Advancing position by concrete int should always be successful"); + + const auto *NewPos = getIteratorPosition(NewState, Iter); + assert(NewPos && + "Iterator should have position after successful advancement"); + + State = setIteratorPosition(State, Iter, *NewPos); + State = setIteratorPosition(State, RetVal, Postfix ? *Pos : *NewPos); + C.addTransition(State); +} + +void IteratorModeling::handleRandomIncrOrDecr(CheckerContext &C, + const Expr *CE, + OverloadedOperatorKind Op, + const SVal &RetVal, + const SVal &LHS, + const SVal &RHS) const { + // Increment or decrement the symbolic expressions which represents the + // position of the iterator + auto State = C.getState(); + + const auto *Pos = getIteratorPosition(State, LHS); + if (!Pos) + return; + + const auto *value = &RHS; + if (auto loc = RHS.getAs<Loc>()) { + const auto val = State->getRawSVal(*loc); + value = &val; + } + + auto &TgtVal = (Op == OO_PlusEqual || Op == OO_MinusEqual) ? LHS : RetVal; + + auto NewState = + advancePosition(State, LHS, Op, *value); + if (NewState) { + const auto *NewPos = getIteratorPosition(NewState, LHS); + assert(NewPos && + "Iterator should have position after successful advancement"); + + State = setIteratorPosition(NewState, TgtVal, *NewPos); + C.addTransition(State); + } else { + assignToContainer(C, CE, TgtVal, Pos->getContainer()); + } +} + +void IteratorModeling::handleBegin(CheckerContext &C, const Expr *CE, + const SVal &RetVal, const SVal &Cont) const { + const auto *ContReg = Cont.getAsRegion(); + if (!ContReg) + return; + + ContReg = ContReg->getMostDerivedObjectRegion(); + + // If the container already has a begin symbol then use it. Otherwise first + // create a new one. + auto State = C.getState(); + auto BeginSym = getContainerBegin(State, ContReg); + if (!BeginSym) { + State = createContainerBegin(State, ContReg, CE, C.getASTContext().LongTy, + C.getLocationContext(), C.blockCount()); + BeginSym = getContainerBegin(State, ContReg); + } + State = setIteratorPosition(State, RetVal, + IteratorPosition::getPosition(ContReg, BeginSym)); + C.addTransition(State); +} + +void IteratorModeling::handleEnd(CheckerContext &C, const Expr *CE, + const SVal &RetVal, const SVal &Cont) const { + const auto *ContReg = Cont.getAsRegion(); + if (!ContReg) + return; + + ContReg = ContReg->getMostDerivedObjectRegion(); + + // If the container already has an end symbol then use it. Otherwise first + // create a new one. + auto State = C.getState(); + auto EndSym = getContainerEnd(State, ContReg); + if (!EndSym) { + State = createContainerEnd(State, ContReg, CE, C.getASTContext().LongTy, + C.getLocationContext(), C.blockCount()); + EndSym = getContainerEnd(State, ContReg); + } + State = setIteratorPosition(State, RetVal, + IteratorPosition::getPosition(ContReg, EndSym)); + C.addTransition(State); +} + +void IteratorModeling::assignToContainer(CheckerContext &C, const Expr *CE, + const SVal &RetVal, + const MemRegion *Cont) const { + Cont = Cont->getMostDerivedObjectRegion(); + + auto State = C.getState(); + auto &SymMgr = C.getSymbolManager(); + auto Sym = SymMgr.conjureSymbol(CE, C.getLocationContext(), + C.getASTContext().LongTy, C.blockCount()); + State = assumeNoOverflow(State, Sym, 4); + State = setIteratorPosition(State, RetVal, + IteratorPosition::getPosition(Cont, Sym)); + C.addTransition(State); +} + +void IteratorModeling::handleAssign(CheckerContext &C, const SVal &Cont, + const Expr *CE, const SVal &OldCont) const { + const auto *ContReg = Cont.getAsRegion(); + if (!ContReg) + return; + + ContReg = ContReg->getMostDerivedObjectRegion(); + + // Assignment of a new value to a container always invalidates all its + // iterators + auto State = C.getState(); + const auto CData = getContainerData(State, ContReg); + if (CData) { + State = invalidateAllIteratorPositions(State, ContReg); + } + + // In case of move, iterators of the old container (except the past-end + // iterators) remain valid but refer to the new container + if (!OldCont.isUndef()) { + const auto *OldContReg = OldCont.getAsRegion(); + if (OldContReg) { + OldContReg = OldContReg->getMostDerivedObjectRegion(); + const auto OldCData = getContainerData(State, OldContReg); + if (OldCData) { + if (const auto OldEndSym = OldCData->getEnd()) { + // If we already assigned an "end" symbol to the old container, then + // first reassign all iterator positions to the new container which + // are not past the container (thus not greater or equal to the + // current "end" symbol). + State = reassignAllIteratorPositionsUnless(State, OldContReg, ContReg, + OldEndSym, BO_GE); + auto &SymMgr = C.getSymbolManager(); + auto &SVB = C.getSValBuilder(); + // Then generate and assign a new "end" symbol for the new container. + auto NewEndSym = + SymMgr.conjureSymbol(CE, C.getLocationContext(), + C.getASTContext().LongTy, C.blockCount()); + State = assumeNoOverflow(State, NewEndSym, 4); + if (CData) { + State = setContainerData(State, ContReg, CData->newEnd(NewEndSym)); + } else { + State = setContainerData(State, ContReg, + ContainerData::fromEnd(NewEndSym)); + } + // Finally, replace the old "end" symbol in the already reassigned + // iterator positions with the new "end" symbol. + State = rebaseSymbolInIteratorPositionsIf( + State, SVB, OldEndSym, NewEndSym, OldEndSym, BO_LT); + } else { + // There was no "end" symbol assigned yet to the old container, + // so reassign all iterator positions to the new container. + State = reassignAllIteratorPositions(State, OldContReg, ContReg); + } + if (const auto OldBeginSym = OldCData->getBegin()) { + // If we already assigned a "begin" symbol to the old container, then + // assign it to the new container and remove it from the old one. + if (CData) { + State = + setContainerData(State, ContReg, CData->newBegin(OldBeginSym)); + } else { + State = setContainerData(State, ContReg, + ContainerData::fromBegin(OldBeginSym)); + } + State = + setContainerData(State, OldContReg, OldCData->newEnd(nullptr)); + } + } else { + // There was neither "begin" nor "end" symbol assigned yet to the old + // container, so reassign all iterator positions to the new container. + State = reassignAllIteratorPositions(State, OldContReg, ContReg); + } + } + } + C.addTransition(State); +} + +void IteratorModeling::handleClear(CheckerContext &C, const SVal &Cont) const { + const auto *ContReg = Cont.getAsRegion(); + if (!ContReg) + return; + + ContReg = ContReg->getMostDerivedObjectRegion(); + + // The clear() operation invalidates all the iterators, except the past-end + // iterators of list-like containers + auto State = C.getState(); + if (!hasSubscriptOperator(State, ContReg) || + !backModifiable(State, ContReg)) { + const auto CData = getContainerData(State, ContReg); + if (CData) { + if (const auto EndSym = CData->getEnd()) { + State = + invalidateAllIteratorPositionsExcept(State, ContReg, EndSym, BO_GE); + C.addTransition(State); + return; + } + } + } + State = invalidateAllIteratorPositions(State, ContReg); + C.addTransition(State); +} + +void IteratorModeling::handlePushBack(CheckerContext &C, + const SVal &Cont) const { + const auto *ContReg = Cont.getAsRegion(); + if (!ContReg) + return; + + ContReg = ContReg->getMostDerivedObjectRegion(); + + // For deque-like containers invalidate all iterator positions + auto State = C.getState(); + if (hasSubscriptOperator(State, ContReg) && frontModifiable(State, ContReg)) { + State = invalidateAllIteratorPositions(State, ContReg); + C.addTransition(State); + return; + } + + const auto CData = getContainerData(State, ContReg); + if (!CData) + return; + + // For vector-like containers invalidate the past-end iterator positions + if (const auto EndSym = CData->getEnd()) { + if (hasSubscriptOperator(State, ContReg)) { + State = invalidateIteratorPositions(State, EndSym, BO_GE); + } + auto &SymMgr = C.getSymbolManager(); + auto &BVF = SymMgr.getBasicVals(); + auto &SVB = C.getSValBuilder(); + const auto newEndSym = + SVB.evalBinOp(State, BO_Add, + nonloc::SymbolVal(EndSym), + nonloc::ConcreteInt(BVF.getValue(llvm::APSInt::get(1))), + SymMgr.getType(EndSym)).getAsSymbol(); + State = setContainerData(State, ContReg, CData->newEnd(newEndSym)); + } + C.addTransition(State); +} + +void IteratorModeling::handlePopBack(CheckerContext &C, + const SVal &Cont) const { + const auto *ContReg = Cont.getAsRegion(); + if (!ContReg) + return; + + ContReg = ContReg->getMostDerivedObjectRegion(); + + auto State = C.getState(); + const auto CData = getContainerData(State, ContReg); + if (!CData) + return; + + if (const auto EndSym = CData->getEnd()) { + auto &SymMgr = C.getSymbolManager(); + auto &BVF = SymMgr.getBasicVals(); + auto &SVB = C.getSValBuilder(); + const auto BackSym = + SVB.evalBinOp(State, BO_Sub, + nonloc::SymbolVal(EndSym), + nonloc::ConcreteInt(BVF.getValue(llvm::APSInt::get(1))), + SymMgr.getType(EndSym)).getAsSymbol(); + // For vector-like and deque-like containers invalidate the last and the + // past-end iterator positions. For list-like containers only invalidate + // the last position + if (hasSubscriptOperator(State, ContReg) && + backModifiable(State, ContReg)) { + State = invalidateIteratorPositions(State, BackSym, BO_GE); + State = setContainerData(State, ContReg, CData->newEnd(nullptr)); + } else { + State = invalidateIteratorPositions(State, BackSym, BO_EQ); + } + auto newEndSym = BackSym; + State = setContainerData(State, ContReg, CData->newEnd(newEndSym)); + C.addTransition(State); + } +} + +void IteratorModeling::handlePushFront(CheckerContext &C, + const SVal &Cont) const { + const auto *ContReg = Cont.getAsRegion(); + if (!ContReg) + return; + + ContReg = ContReg->getMostDerivedObjectRegion(); + + // For deque-like containers invalidate all iterator positions + auto State = C.getState(); + if (hasSubscriptOperator(State, ContReg)) { + State = invalidateAllIteratorPositions(State, ContReg); + C.addTransition(State); + } else { + const auto CData = getContainerData(State, ContReg); + if (!CData) + return; + + if (const auto BeginSym = CData->getBegin()) { + auto &SymMgr = C.getSymbolManager(); + auto &BVF = SymMgr.getBasicVals(); + auto &SVB = C.getSValBuilder(); + const auto newBeginSym = + SVB.evalBinOp(State, BO_Sub, + nonloc::SymbolVal(BeginSym), + nonloc::ConcreteInt(BVF.getValue(llvm::APSInt::get(1))), + SymMgr.getType(BeginSym)).getAsSymbol(); + State = setContainerData(State, ContReg, CData->newBegin(newBeginSym)); + C.addTransition(State); + } + } +} + +void IteratorModeling::handlePopFront(CheckerContext &C, + const SVal &Cont) const { + const auto *ContReg = Cont.getAsRegion(); + if (!ContReg) + return; + + ContReg = ContReg->getMostDerivedObjectRegion(); + + auto State = C.getState(); + const auto CData = getContainerData(State, ContReg); + if (!CData) + return; + + // For deque-like containers invalidate all iterator positions. For list-like + // iterators only invalidate the first position + if (const auto BeginSym = CData->getBegin()) { + if (hasSubscriptOperator(State, ContReg)) { + State = invalidateIteratorPositions(State, BeginSym, BO_LE); + } else { + State = invalidateIteratorPositions(State, BeginSym, BO_EQ); + } + auto &SymMgr = C.getSymbolManager(); + auto &BVF = SymMgr.getBasicVals(); + auto &SVB = C.getSValBuilder(); + const auto newBeginSym = + SVB.evalBinOp(State, BO_Add, + nonloc::SymbolVal(BeginSym), + nonloc::ConcreteInt(BVF.getValue(llvm::APSInt::get(1))), + SymMgr.getType(BeginSym)).getAsSymbol(); + State = setContainerData(State, ContReg, CData->newBegin(newBeginSym)); + C.addTransition(State); + } +} + +void IteratorModeling::handleInsert(CheckerContext &C, const SVal &Iter) const { + auto State = C.getState(); + const auto *Pos = getIteratorPosition(State, Iter); + if (!Pos) + return; + + // For deque-like containers invalidate all iterator positions. For + // vector-like containers invalidate iterator positions after the insertion. + const auto *Cont = Pos->getContainer(); + if (hasSubscriptOperator(State, Cont) && backModifiable(State, Cont)) { + if (frontModifiable(State, Cont)) { + State = invalidateAllIteratorPositions(State, Cont); + } else { + State = invalidateIteratorPositions(State, Pos->getOffset(), BO_GE); + } + if (const auto *CData = getContainerData(State, Cont)) { + if (const auto EndSym = CData->getEnd()) { + State = invalidateIteratorPositions(State, EndSym, BO_GE); + State = setContainerData(State, Cont, CData->newEnd(nullptr)); + } + } + C.addTransition(State); + } +} + +void IteratorModeling::handleErase(CheckerContext &C, const SVal &Iter) const { + auto State = C.getState(); + const auto *Pos = getIteratorPosition(State, Iter); + if (!Pos) + return; + + // For deque-like containers invalidate all iterator positions. For + // vector-like containers invalidate iterator positions at and after the + // deletion. For list-like containers only invalidate the deleted position. + const auto *Cont = Pos->getContainer(); + if (hasSubscriptOperator(State, Cont) && backModifiable(State, Cont)) { + if (frontModifiable(State, Cont)) { + State = invalidateAllIteratorPositions(State, Cont); + } else { + State = invalidateIteratorPositions(State, Pos->getOffset(), BO_GE); + } + if (const auto *CData = getContainerData(State, Cont)) { + if (const auto EndSym = CData->getEnd()) { + State = invalidateIteratorPositions(State, EndSym, BO_GE); + State = setContainerData(State, Cont, CData->newEnd(nullptr)); + } + } + } else { + State = invalidateIteratorPositions(State, Pos->getOffset(), BO_EQ); + } + C.addTransition(State); +} + +void IteratorModeling::handleErase(CheckerContext &C, const SVal &Iter1, + const SVal &Iter2) const { + auto State = C.getState(); + const auto *Pos1 = getIteratorPosition(State, Iter1); + const auto *Pos2 = getIteratorPosition(State, Iter2); + if (!Pos1 || !Pos2) + return; + + // For deque-like containers invalidate all iterator positions. For + // vector-like containers invalidate iterator positions at and after the + // deletion range. For list-like containers only invalidate the deleted + // position range [first..last]. + const auto *Cont = Pos1->getContainer(); + if (hasSubscriptOperator(State, Cont) && backModifiable(State, Cont)) { + if (frontModifiable(State, Cont)) { + State = invalidateAllIteratorPositions(State, Cont); + } else { + State = invalidateIteratorPositions(State, Pos1->getOffset(), BO_GE); + } + if (const auto *CData = getContainerData(State, Cont)) { + if (const auto EndSym = CData->getEnd()) { + State = invalidateIteratorPositions(State, EndSym, BO_GE); + State = setContainerData(State, Cont, CData->newEnd(nullptr)); + } + } + } else { + State = invalidateIteratorPositions(State, Pos1->getOffset(), BO_GE, + Pos2->getOffset(), BO_LT); + } + C.addTransition(State); +} + +void IteratorModeling::handleEraseAfter(CheckerContext &C, + const SVal &Iter) const { + auto State = C.getState(); + const auto *Pos = getIteratorPosition(State, Iter); + if (!Pos) + return; + + // Invalidate the deleted iterator position, which is the position of the + // parameter plus one. + auto &SymMgr = C.getSymbolManager(); + auto &BVF = SymMgr.getBasicVals(); + auto &SVB = C.getSValBuilder(); + const auto NextSym = + SVB.evalBinOp(State, BO_Add, + nonloc::SymbolVal(Pos->getOffset()), + nonloc::ConcreteInt(BVF.getValue(llvm::APSInt::get(1))), + SymMgr.getType(Pos->getOffset())).getAsSymbol(); + State = invalidateIteratorPositions(State, NextSym, BO_EQ); + C.addTransition(State); +} + +void IteratorModeling::handleEraseAfter(CheckerContext &C, const SVal &Iter1, + const SVal &Iter2) const { + auto State = C.getState(); + const auto *Pos1 = getIteratorPosition(State, Iter1); + const auto *Pos2 = getIteratorPosition(State, Iter2); + if (!Pos1 || !Pos2) + return; + + // Invalidate the deleted iterator position range (first..last) + State = invalidateIteratorPositions(State, Pos1->getOffset(), BO_GT, + Pos2->getOffset(), BO_LT); + C.addTransition(State); +} + +namespace { + +const CXXRecordDecl *getCXXRecordDecl(ProgramStateRef State, + const MemRegion *Reg); + +bool isBeginCall(const FunctionDecl *Func) { + const auto *IdInfo = Func->getIdentifier(); + if (!IdInfo) + return false; + return IdInfo->getName().endswith_lower("begin"); +} + +bool isEndCall(const FunctionDecl *Func) { + const auto *IdInfo = Func->getIdentifier(); + if (!IdInfo) + return false; + return IdInfo->getName().endswith_lower("end"); +} + +bool isAssignCall(const FunctionDecl *Func) { + const auto *IdInfo = Func->getIdentifier(); + if (!IdInfo) + return false; + if (Func->getNumParams() > 2) + return false; + return IdInfo->getName() == "assign"; +} + +bool isClearCall(const FunctionDecl *Func) { + const auto *IdInfo = Func->getIdentifier(); + if (!IdInfo) + return false; + if (Func->getNumParams() > 0) + return false; + return IdInfo->getName() == "clear"; +} + +bool isPushBackCall(const FunctionDecl *Func) { + const auto *IdInfo = Func->getIdentifier(); + if (!IdInfo) + return false; + if (Func->getNumParams() != 1) + return false; + return IdInfo->getName() == "push_back"; +} + +bool isEmplaceBackCall(const FunctionDecl *Func) { + const auto *IdInfo = Func->getIdentifier(); + if (!IdInfo) + return false; + if (Func->getNumParams() < 1) + return false; + return IdInfo->getName() == "emplace_back"; +} + +bool isPopBackCall(const FunctionDecl *Func) { + const auto *IdInfo = Func->getIdentifier(); + if (!IdInfo) + return false; + if (Func->getNumParams() > 0) + return false; + return IdInfo->getName() == "pop_back"; +} + +bool isPushFrontCall(const FunctionDecl *Func) { + const auto *IdInfo = Func->getIdentifier(); + if (!IdInfo) + return false; + if (Func->getNumParams() != 1) + return false; + return IdInfo->getName() == "push_front"; +} + +bool isEmplaceFrontCall(const FunctionDecl *Func) { + const auto *IdInfo = Func->getIdentifier(); + if (!IdInfo) + return false; + if (Func->getNumParams() < 1) + return false; + return IdInfo->getName() == "emplace_front"; +} + +bool isPopFrontCall(const FunctionDecl *Func) { + const auto *IdInfo = Func->getIdentifier(); + if (!IdInfo) + return false; + if (Func->getNumParams() > 0) + return false; + return IdInfo->getName() == "pop_front"; +} + +bool isAssignmentOperator(OverloadedOperatorKind OK) { return OK == OO_Equal; } + +bool isSimpleComparisonOperator(OverloadedOperatorKind OK) { + return OK == OO_EqualEqual || OK == OO_ExclaimEqual; +} + +bool hasSubscriptOperator(ProgramStateRef State, const MemRegion *Reg) { + const auto *CRD = getCXXRecordDecl(State, Reg); + if (!CRD) + return false; + + for (const auto *Method : CRD->methods()) { + if (!Method->isOverloadedOperator()) + continue; + const auto OPK = Method->getOverloadedOperator(); + if (OPK == OO_Subscript) { + return true; + } + } + return false; +} + +bool frontModifiable(ProgramStateRef State, const MemRegion *Reg) { + const auto *CRD = getCXXRecordDecl(State, Reg); + if (!CRD) + return false; + + for (const auto *Method : CRD->methods()) { + if (!Method->getDeclName().isIdentifier()) + continue; + if (Method->getName() == "push_front" || Method->getName() == "pop_front") { + return true; + } + } + return false; +} + +bool backModifiable(ProgramStateRef State, const MemRegion *Reg) { + const auto *CRD = getCXXRecordDecl(State, Reg); + if (!CRD) + return false; + + for (const auto *Method : CRD->methods()) { + if (!Method->getDeclName().isIdentifier()) + continue; + if (Method->getName() == "push_back" || Method->getName() == "pop_back") { + return true; + } + } + return false; +} + +const CXXRecordDecl *getCXXRecordDecl(ProgramStateRef State, + const MemRegion *Reg) { + auto TI = getDynamicTypeInfo(State, Reg); + if (!TI.isValid()) + return nullptr; + + auto Type = TI.getType(); + if (const auto *RefT = Type->getAs<ReferenceType>()) { + Type = RefT->getPointeeType(); + } + + return Type->getUnqualifiedDesugaredType()->getAsCXXRecordDecl(); +} + +SymbolRef getContainerBegin(ProgramStateRef State, const MemRegion *Cont) { + const auto *CDataPtr = getContainerData(State, Cont); + if (!CDataPtr) + return nullptr; + + return CDataPtr->getBegin(); +} + +SymbolRef getContainerEnd(ProgramStateRef State, const MemRegion *Cont) { + const auto *CDataPtr = getContainerData(State, Cont); + if (!CDataPtr) + return nullptr; + + return CDataPtr->getEnd(); +} + +ProgramStateRef createContainerBegin(ProgramStateRef State, + const MemRegion *Cont, const Expr *E, + QualType T, const LocationContext *LCtx, + unsigned BlockCount) { + // Only create if it does not exist + const auto *CDataPtr = getContainerData(State, Cont); + if (CDataPtr && CDataPtr->getBegin()) + return State; + + auto &SymMgr = State->getSymbolManager(); + const SymbolConjured *Sym = SymMgr.conjureSymbol(E, LCtx, T, BlockCount, + "begin"); + State = assumeNoOverflow(State, Sym, 4); + + if (CDataPtr) { + const auto CData = CDataPtr->newBegin(Sym); + return setContainerData(State, Cont, CData); + } + + const auto CData = ContainerData::fromBegin(Sym); + return setContainerData(State, Cont, CData); +} + +ProgramStateRef createContainerEnd(ProgramStateRef State, const MemRegion *Cont, + const Expr *E, QualType T, + const LocationContext *LCtx, + unsigned BlockCount) { + // Only create if it does not exist + const auto *CDataPtr = getContainerData(State, Cont); + if (CDataPtr && CDataPtr->getEnd()) + return State; + + auto &SymMgr = State->getSymbolManager(); + const SymbolConjured *Sym = SymMgr.conjureSymbol(E, LCtx, T, BlockCount, + "end"); + State = assumeNoOverflow(State, Sym, 4); + + if (CDataPtr) { + const auto CData = CDataPtr->newEnd(Sym); + return setContainerData(State, Cont, CData); + } + + const auto CData = ContainerData::fromEnd(Sym); + return setContainerData(State, Cont, CData); +} + +ProgramStateRef setContainerData(ProgramStateRef State, const MemRegion *Cont, + const ContainerData &CData) { + return State->set<ContainerMap>(Cont, CData); +} + +ProgramStateRef removeIteratorPosition(ProgramStateRef State, const SVal &Val) { + if (auto Reg = Val.getAsRegion()) { + Reg = Reg->getMostDerivedObjectRegion(); + return State->remove<IteratorRegionMap>(Reg); + } else if (const auto Sym = Val.getAsSymbol()) { + return State->remove<IteratorSymbolMap>(Sym); + } else if (const auto LCVal = Val.getAs<nonloc::LazyCompoundVal>()) { + return State->remove<IteratorRegionMap>(LCVal->getRegion()); + } + return nullptr; +} + +// This function tells the analyzer's engine that symbols produced by our +// checker, most notably iterator positions, are relatively small. +// A distance between items in the container should not be very large. +// By assuming that it is within around 1/8 of the address space, +// we can help the analyzer perform operations on these symbols +// without being afraid of integer overflows. +// FIXME: Should we provide it as an API, so that all checkers could use it? +ProgramStateRef assumeNoOverflow(ProgramStateRef State, SymbolRef Sym, + long Scale) { + SValBuilder &SVB = State->getStateManager().getSValBuilder(); + BasicValueFactory &BV = SVB.getBasicValueFactory(); + + QualType T = Sym->getType(); + assert(T->isSignedIntegerOrEnumerationType()); + APSIntType AT = BV.getAPSIntType(T); + + ProgramStateRef NewState = State; + + llvm::APSInt Max = AT.getMaxValue() / AT.getValue(Scale); + SVal IsCappedFromAbove = + SVB.evalBinOpNN(State, BO_LE, nonloc::SymbolVal(Sym), + nonloc::ConcreteInt(Max), SVB.getConditionType()); + if (auto DV = IsCappedFromAbove.getAs<DefinedSVal>()) { + NewState = NewState->assume(*DV, true); + if (!NewState) + return State; + } + + llvm::APSInt Min = -Max; + SVal IsCappedFromBelow = + SVB.evalBinOpNN(State, BO_GE, nonloc::SymbolVal(Sym), + nonloc::ConcreteInt(Min), SVB.getConditionType()); + if (auto DV = IsCappedFromBelow.getAs<DefinedSVal>()) { + NewState = NewState->assume(*DV, true); + if (!NewState) + return State; + } + + return NewState; +} + +ProgramStateRef relateSymbols(ProgramStateRef State, SymbolRef Sym1, + SymbolRef Sym2, bool Equal) { + auto &SVB = State->getStateManager().getSValBuilder(); + + // FIXME: This code should be reworked as follows: + // 1. Subtract the operands using evalBinOp(). + // 2. Assume that the result doesn't overflow. + // 3. Compare the result to 0. + // 4. Assume the result of the comparison. + const auto comparison = + SVB.evalBinOp(State, BO_EQ, nonloc::SymbolVal(Sym1), + nonloc::SymbolVal(Sym2), SVB.getConditionType()); + + assert(comparison.getAs<DefinedSVal>() && + "Symbol comparison must be a `DefinedSVal`"); + + auto NewState = State->assume(comparison.castAs<DefinedSVal>(), Equal); + if (!NewState) + return nullptr; + + if (const auto CompSym = comparison.getAsSymbol()) { + assert(isa<SymIntExpr>(CompSym) && + "Symbol comparison must be a `SymIntExpr`"); + assert(BinaryOperator::isComparisonOp( + cast<SymIntExpr>(CompSym)->getOpcode()) && + "Symbol comparison must be a comparison"); + return assumeNoOverflow(NewState, cast<SymIntExpr>(CompSym)->getLHS(), 2); + } + + return NewState; +} + +bool hasLiveIterators(ProgramStateRef State, const MemRegion *Cont) { + auto RegionMap = State->get<IteratorRegionMap>(); + for (const auto Reg : RegionMap) { + if (Reg.second.getContainer() == Cont) + return true; + } + + auto SymbolMap = State->get<IteratorSymbolMap>(); + for (const auto Sym : SymbolMap) { + if (Sym.second.getContainer() == Cont) + return true; + } + + return false; +} + +bool isBoundThroughLazyCompoundVal(const Environment &Env, + const MemRegion *Reg) { + for (const auto Binding: Env) { + if (const auto LCVal = Binding.second.getAs<nonloc::LazyCompoundVal>()) { + if (LCVal->getRegion() == Reg) + return true; + } + } + + return false; +} + +template <typename Condition, typename Process> +ProgramStateRef processIteratorPositions(ProgramStateRef State, Condition Cond, + Process Proc) { + auto &RegionMapFactory = State->get_context<IteratorRegionMap>(); + auto RegionMap = State->get<IteratorRegionMap>(); + bool Changed = false; + for (const auto Reg : RegionMap) { + if (Cond(Reg.second)) { + RegionMap = RegionMapFactory.add(RegionMap, Reg.first, Proc(Reg.second)); + Changed = true; + } + } + + if (Changed) + State = State->set<IteratorRegionMap>(RegionMap); + + auto &SymbolMapFactory = State->get_context<IteratorSymbolMap>(); + auto SymbolMap = State->get<IteratorSymbolMap>(); + Changed = false; + for (const auto Sym : SymbolMap) { + if (Cond(Sym.second)) { + SymbolMap = SymbolMapFactory.add(SymbolMap, Sym.first, Proc(Sym.second)); + Changed = true; + } + } + + if (Changed) + State = State->set<IteratorSymbolMap>(SymbolMap); + + return State; +} + +ProgramStateRef invalidateAllIteratorPositions(ProgramStateRef State, + const MemRegion *Cont) { + auto MatchCont = [&](const IteratorPosition &Pos) { + return Pos.getContainer() == Cont; + }; + auto Invalidate = [&](const IteratorPosition &Pos) { + return Pos.invalidate(); + }; + return processIteratorPositions(State, MatchCont, Invalidate); +} + +ProgramStateRef +invalidateAllIteratorPositionsExcept(ProgramStateRef State, + const MemRegion *Cont, SymbolRef Offset, + BinaryOperator::Opcode Opc) { + auto MatchContAndCompare = [&](const IteratorPosition &Pos) { + return Pos.getContainer() == Cont && + !compare(State, Pos.getOffset(), Offset, Opc); + }; + auto Invalidate = [&](const IteratorPosition &Pos) { + return Pos.invalidate(); + }; + return processIteratorPositions(State, MatchContAndCompare, Invalidate); +} + +ProgramStateRef invalidateIteratorPositions(ProgramStateRef State, + SymbolRef Offset, + BinaryOperator::Opcode Opc) { + auto Compare = [&](const IteratorPosition &Pos) { + return compare(State, Pos.getOffset(), Offset, Opc); + }; + auto Invalidate = [&](const IteratorPosition &Pos) { + return Pos.invalidate(); + }; + return processIteratorPositions(State, Compare, Invalidate); +} + +ProgramStateRef invalidateIteratorPositions(ProgramStateRef State, + SymbolRef Offset1, + BinaryOperator::Opcode Opc1, + SymbolRef Offset2, + BinaryOperator::Opcode Opc2) { + auto Compare = [&](const IteratorPosition &Pos) { + return compare(State, Pos.getOffset(), Offset1, Opc1) && + compare(State, Pos.getOffset(), Offset2, Opc2); + }; + auto Invalidate = [&](const IteratorPosition &Pos) { + return Pos.invalidate(); + }; + return processIteratorPositions(State, Compare, Invalidate); +} + +ProgramStateRef reassignAllIteratorPositions(ProgramStateRef State, + const MemRegion *Cont, + const MemRegion *NewCont) { + auto MatchCont = [&](const IteratorPosition &Pos) { + return Pos.getContainer() == Cont; + }; + auto ReAssign = [&](const IteratorPosition &Pos) { + return Pos.reAssign(NewCont); + }; + return processIteratorPositions(State, MatchCont, ReAssign); +} + +ProgramStateRef reassignAllIteratorPositionsUnless(ProgramStateRef State, + const MemRegion *Cont, + const MemRegion *NewCont, + SymbolRef Offset, + BinaryOperator::Opcode Opc) { + auto MatchContAndCompare = [&](const IteratorPosition &Pos) { + return Pos.getContainer() == Cont && + !compare(State, Pos.getOffset(), Offset, Opc); + }; + auto ReAssign = [&](const IteratorPosition &Pos) { + return Pos.reAssign(NewCont); + }; + return processIteratorPositions(State, MatchContAndCompare, ReAssign); +} + +// This function rebases symbolic expression `OldSym + Int` to `NewSym + Int`, +// `OldSym - Int` to `NewSym - Int` and `OldSym` to `NewSym` in any iterator +// position offsets where `CondSym` is true. +ProgramStateRef rebaseSymbolInIteratorPositionsIf( + ProgramStateRef State, SValBuilder &SVB, SymbolRef OldSym, + SymbolRef NewSym, SymbolRef CondSym, BinaryOperator::Opcode Opc) { + auto LessThanEnd = [&](const IteratorPosition &Pos) { + return compare(State, Pos.getOffset(), CondSym, Opc); + }; + auto RebaseSymbol = [&](const IteratorPosition &Pos) { + return Pos.setTo(rebaseSymbol(State, SVB, Pos.getOffset(), OldSym, + NewSym)); + }; + return processIteratorPositions(State, LessThanEnd, RebaseSymbol); +} + +// This function rebases symbolic expression `OldExpr + Int` to `NewExpr + Int`, +// `OldExpr - Int` to `NewExpr - Int` and `OldExpr` to `NewExpr` in expression +// `OrigExpr`. +SymbolRef rebaseSymbol(ProgramStateRef State, SValBuilder &SVB, + SymbolRef OrigExpr, SymbolRef OldExpr, + SymbolRef NewSym) { + auto &SymMgr = SVB.getSymbolManager(); + auto Diff = SVB.evalBinOpNN(State, BO_Sub, nonloc::SymbolVal(OrigExpr), + nonloc::SymbolVal(OldExpr), + SymMgr.getType(OrigExpr)); + + const auto DiffInt = Diff.getAs<nonloc::ConcreteInt>(); + if (!DiffInt) + return OrigExpr; + + return SVB.evalBinOpNN(State, BO_Add, *DiffInt, nonloc::SymbolVal(NewSym), + SymMgr.getType(OrigExpr)).getAsSymbol(); +} + +} // namespace + +void ento::registerIteratorModeling(CheckerManager &mgr) { + mgr.registerChecker<IteratorModeling>(); +} + +bool ento::shouldRegisterIteratorModeling(const LangOptions &LO) { + return true; +} |
