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llvm-project/clang/lib/StaticAnalyzer/Checkers/IteratorModeling.cpp
Mark de Wever b6d9e97662 [Analyzer] Fixes -Wrange-loop-analysis warnings 
This avoids new warnings due to D68912 adds -Wrange-loop-analysis to -Wall.

Differential Revision: https://reviews.llvm.org/D71809
2019-12-22 19:13:34 +01:00

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//===-- 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, 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;
void printState(raw_ostream &Out, ProgramStateRef State, const char *NL,
const char *Sep) const override;
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,
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);
}
// We cannot make assumpotions on `UnknownVal`. Let us conjure a symbol
// instead.
if (RetVal.isUnknown()) {
auto &SymMgr = C.getSymbolManager();
auto *LCtx = C.getLocationContext();
RetVal = nonloc::SymbolVal(SymMgr.conjureSymbol(
CE, LCtx, C.getASTContext().BoolTy, C.blockCount()));
State = State->BindExpr(CE, LCtx, RetVal);
}
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);
}
void IteratorModeling::printState(raw_ostream &Out, ProgramStateRef State,
const char *NL, const char *Sep) const {
auto ContMap = State->get<ContainerMap>();
if (!ContMap.isEmpty()) {
Out << Sep << "Container Data :" << NL;
for (const auto &Cont : ContMap) {
Cont.first->dumpToStream(Out);
Out << " : [ ";
const auto CData = Cont.second;
if (CData.getBegin())
CData.getBegin()->dumpToStream(Out);
else
Out << "<Unknown>";
Out << " .. ";
if (CData.getEnd())
CData.getEnd()->dumpToStream(Out);
else
Out << "<Unknown>";
Out << " ]" << NL;
}
}
auto SymbolMap = State->get<IteratorSymbolMap>();
auto RegionMap = State->get<IteratorRegionMap>();
if (!SymbolMap.isEmpty() || !RegionMap.isEmpty()) {
Out << Sep << "Iterator Positions :" << NL;
for (const auto &Sym : SymbolMap) {
Sym.first->dumpToStream(Out);
Out << " : ";
const auto Pos = Sym.second;
Out << (Pos.isValid() ? "Valid" : "Invalid") << " ; Container == ";
Pos.getContainer()->dumpToStream(Out);
Out<<" ; Offset == ";
Pos.getOffset()->dumpToStream(Out);
}
for (const auto &Reg : RegionMap) {
Reg.first->dumpToStream(Out);
Out << " : ";
const auto Pos = Reg.second;
Out << (Pos.isValid() ? "Valid" : "Invalid") << " ; Container == ";
Pos.getContainer()->dumpToStream(Out);
Out<<" ; Offset == ";
Pos.getOffset()->dumpToStream(Out);
}
}
}
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;
}
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