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llvm-project/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp

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//=-- ExprEngine.cpp - Path-Sensitive Expression-Level Dataflow ---*- C++ -*-=
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines a meta-engine for path-sensitive dataflow analysis that
// is built on GREngine, but provides the boilerplate to execute transfer
// functions and build the ExplodedGraph at the expression level.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "ExprEngine"
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ObjCMessage.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/ParentMap.h"
#include "clang/AST/StmtObjC.h"
#include "clang/AST/StmtCXX.h"
#include "clang/AST/DeclCXX.h"
#include "clang/Basic/Builtins.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/PrettyStackTrace.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/ADT/ImmutableList.h"
#include "llvm/ADT/Statistic.h"
#ifndef NDEBUG
#include "llvm/Support/GraphWriter.h"
#endif
using namespace clang;
using namespace ento;
using llvm::APSInt;
STATISTIC(NumRemoveDeadBindings,
"The # of times RemoveDeadBindings is called");
STATISTIC(NumRemoveDeadBindingsSkipped,
"The # of times RemoveDeadBindings is skipped");
//===----------------------------------------------------------------------===//
// Utility functions.
//===----------------------------------------------------------------------===//
static inline Selector GetNullarySelector(const char* name, ASTContext &Ctx) {
IdentifierInfo* II = &Ctx.Idents.get(name);
return Ctx.Selectors.getSelector(0, &II);
}
//===----------------------------------------------------------------------===//
// Engine construction and deletion.
//===----------------------------------------------------------------------===//
ExprEngine::ExprEngine(AnalysisManager &mgr, bool gcEnabled,
SetOfDecls *VisitedCallees)
: AMgr(mgr),
AnalysisDeclContexts(mgr.getAnalysisDeclContextManager()),
Engine(*this, VisitedCallees),
G(Engine.getGraph()),
StateMgr(getContext(), mgr.getStoreManagerCreator(),
mgr.getConstraintManagerCreator(), G.getAllocator(),
*this),
SymMgr(StateMgr.getSymbolManager()),
svalBuilder(StateMgr.getSValBuilder()),
EntryNode(NULL),
currentStmt(NULL), currentStmtIdx(0), currentBuilderContext(0),
NSExceptionII(NULL), NSExceptionInstanceRaiseSelectors(NULL),
RaiseSel(GetNullarySelector("raise", getContext())),
ObjCGCEnabled(gcEnabled), BR(mgr, *this) {
if (mgr.shouldEagerlyTrimExplodedGraph()) {
// Enable eager node reclaimation when constructing the ExplodedGraph.
G.enableNodeReclamation();
}
}
ExprEngine::~ExprEngine() {
BR.FlushReports();
delete [] NSExceptionInstanceRaiseSelectors;
}
//===----------------------------------------------------------------------===//
// Utility methods.
//===----------------------------------------------------------------------===//
ProgramStateRef ExprEngine::getInitialState(const LocationContext *InitLoc) {
ProgramStateRef state = StateMgr.getInitialState(InitLoc);
const Decl *D = InitLoc->getDecl();
// Preconditions.
// FIXME: It would be nice if we had a more general mechanism to add
// such preconditions. Some day.
do {
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
// Precondition: the first argument of 'main' is an integer guaranteed
// to be > 0.
const IdentifierInfo *II = FD->getIdentifier();
if (!II || !(II->getName() == "main" && FD->getNumParams() > 0))
break;
const ParmVarDecl *PD = FD->getParamDecl(0);
QualType T = PD->getType();
if (!T->isIntegerType())
break;
const MemRegion *R = state->getRegion(PD, InitLoc);
if (!R)
break;
SVal V = state->getSVal(loc::MemRegionVal(R));
SVal Constraint_untested = evalBinOp(state, BO_GT, V,
svalBuilder.makeZeroVal(T),
getContext().IntTy);
DefinedOrUnknownSVal *Constraint =
dyn_cast<DefinedOrUnknownSVal>(&Constraint_untested);
if (!Constraint)
break;
if (ProgramStateRef newState = state->assume(*Constraint, true))
state = newState;
}
break;
}
while (0);
if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
// Precondition: 'self' is always non-null upon entry to an Objective-C
// method.
const ImplicitParamDecl *SelfD = MD->getSelfDecl();
const MemRegion *R = state->getRegion(SelfD, InitLoc);
SVal V = state->getSVal(loc::MemRegionVal(R));
if (const Loc *LV = dyn_cast<Loc>(&V)) {
// Assume that the pointer value in 'self' is non-null.
state = state->assume(*LV, true);
assert(state && "'self' cannot be null");
}
}
if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(D)) {
if (!MD->isStatic()) {
// Precondition: 'this' is always non-null upon entry to the
// top-level function. This is our starting assumption for
// analyzing an "open" program.
const StackFrameContext *SFC = InitLoc->getCurrentStackFrame();
if (SFC->getParent() == 0) {
loc::MemRegionVal L(getCXXThisRegion(MD, SFC));
SVal V = state->getSVal(L);
if (const Loc *LV = dyn_cast<Loc>(&V)) {
state = state->assume(*LV, true);
assert(state && "'this' cannot be null");
}
}
}
}
return state;
}
//===----------------------------------------------------------------------===//
// Top-level transfer function logic (Dispatcher).
//===----------------------------------------------------------------------===//
/// evalAssume - Called by ConstraintManager. Used to call checker-specific
/// logic for handling assumptions on symbolic values.
ProgramStateRef ExprEngine::processAssume(ProgramStateRef state,
SVal cond, bool assumption) {
return getCheckerManager().runCheckersForEvalAssume(state, cond, assumption);
}
bool ExprEngine::wantsRegionChangeUpdate(ProgramStateRef state) {
return getCheckerManager().wantsRegionChangeUpdate(state);
}
ProgramStateRef
ExprEngine::processRegionChanges(ProgramStateRef state,
const StoreManager::InvalidatedSymbols *invalidated,
ArrayRef<const MemRegion *> Explicits,
ArrayRef<const MemRegion *> Regions,
const CallOrObjCMessage *Call) {
return getCheckerManager().runCheckersForRegionChanges(state, invalidated,
Explicits, Regions, Call);
}
void ExprEngine::printState(raw_ostream &Out, ProgramStateRef State,
const char *NL, const char *Sep) {
getCheckerManager().runCheckersForPrintState(Out, State, NL, Sep);
}
void ExprEngine::processEndWorklist(bool hasWorkRemaining) {
getCheckerManager().runCheckersForEndAnalysis(G, BR, *this);
}
void ExprEngine::processCFGElement(const CFGElement E, ExplodedNode *Pred,
unsigned StmtIdx, NodeBuilderContext *Ctx) {
currentStmtIdx = StmtIdx;
currentBuilderContext = Ctx;
switch (E.getKind()) {
case CFGElement::Invalid:
llvm_unreachable("Unexpected CFGElement kind.");
case CFGElement::Statement:
ProcessStmt(const_cast<Stmt*>(E.getAs<CFGStmt>()->getStmt()), Pred);
return;
case CFGElement::Initializer:
ProcessInitializer(E.getAs<CFGInitializer>()->getInitializer(), Pred);
return;
case CFGElement::AutomaticObjectDtor:
case CFGElement::BaseDtor:
case CFGElement::MemberDtor:
case CFGElement::TemporaryDtor:
ProcessImplicitDtor(*E.getAs<CFGImplicitDtor>(), Pred);
return;
}
}
static bool shouldRemoveDeadBindings(AnalysisManager &AMgr,
const CFGStmt S,
const ExplodedNode *Pred,
const LocationContext *LC) {
// Are we never purging state values?
if (AMgr.getPurgeMode() == PurgeNone)
return false;
// Is this the beginning of a basic block?
if (isa<BlockEntrance>(Pred->getLocation()))
return true;
// Is this on a non-expression?
if (!isa<Expr>(S.getStmt()))
return true;
// Run before processing a call.
if (isa<CallExpr>(S.getStmt()))
return true;
// Is this an expression that is consumed by another expression? If so,
// postpone cleaning out the state.
ParentMap &PM = LC->getAnalysisDeclContext()->getParentMap();
return !PM.isConsumedExpr(cast<Expr>(S.getStmt()));
}
void ExprEngine::ProcessStmt(const CFGStmt S,
ExplodedNode *Pred) {
// Reclaim any unnecessary nodes in the ExplodedGraph.
G.reclaimRecentlyAllocatedNodes();
currentStmt = S.getStmt();
PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),
currentStmt->getLocStart(),
"Error evaluating statement");
EntryNode = Pred;
ProgramStateRef EntryState = EntryNode->getState();
CleanedState = EntryState;
// Create the cleaned state.
const LocationContext *LC = EntryNode->getLocationContext();
SymbolReaper SymReaper(LC, currentStmt, SymMgr, getStoreManager());
if (shouldRemoveDeadBindings(AMgr, S, Pred, LC)) {
NumRemoveDeadBindings++;
getCheckerManager().runCheckersForLiveSymbols(CleanedState, SymReaper);
const StackFrameContext *SFC = LC->getCurrentStackFrame();
// Create a state in which dead bindings are removed from the environment
// and the store. TODO: The function should just return new env and store,
// not a new state.
CleanedState = StateMgr.removeDeadBindings(CleanedState, SFC, SymReaper);
} else {
NumRemoveDeadBindingsSkipped++;
}
// Process any special transfer function for dead symbols.
ExplodedNodeSet Tmp;
// A tag to track convenience transitions, which can be removed at cleanup.
static SimpleProgramPointTag cleanupTag("ExprEngine : Clean Node");
if (!SymReaper.hasDeadSymbols()) {
// Generate a CleanedNode that has the environment and store cleaned
// up. Since no symbols are dead, we can optimize and not clean out
// the constraint manager.
StmtNodeBuilder Bldr(Pred, Tmp, *currentBuilderContext);
Bldr.generateNode(currentStmt, EntryNode, CleanedState, false, &cleanupTag);
} else {
// Call checkers with the non-cleaned state so that they could query the
// values of the soon to be dead symbols.
ExplodedNodeSet CheckedSet;
getCheckerManager().runCheckersForDeadSymbols(CheckedSet, EntryNode,
SymReaper, currentStmt, *this);
// For each node in CheckedSet, generate CleanedNodes that have the
// environment, the store, and the constraints cleaned up but have the
// user-supplied states as the predecessors.
StmtNodeBuilder Bldr(CheckedSet, Tmp, *currentBuilderContext);
for (ExplodedNodeSet::const_iterator
I = CheckedSet.begin(), E = CheckedSet.end(); I != E; ++I) {
ProgramStateRef CheckerState = (*I)->getState();
// The constraint manager has not been cleaned up yet, so clean up now.
CheckerState = getConstraintManager().removeDeadBindings(CheckerState,
SymReaper);
assert(StateMgr.haveEqualEnvironments(CheckerState, EntryState) &&
"Checkers are not allowed to modify the Environment as a part of "
"checkDeadSymbols processing.");
assert(StateMgr.haveEqualStores(CheckerState, EntryState) &&
"Checkers are not allowed to modify the Store as a part of "
"checkDeadSymbols processing.");
// Create a state based on CleanedState with CheckerState GDM and
// generate a transition to that state.
ProgramStateRef CleanedCheckerSt =
StateMgr.getPersistentStateWithGDM(CleanedState, CheckerState);
Bldr.generateNode(currentStmt, *I, CleanedCheckerSt, false, &cleanupTag,
ProgramPoint::PostPurgeDeadSymbolsKind);
}
}
ExplodedNodeSet Dst;
for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
ExplodedNodeSet DstI;
// Visit the statement.
Visit(currentStmt, *I, DstI);
Dst.insert(DstI);
}
// Enqueue the new nodes onto the work list.
Engine.enqueue(Dst, currentBuilderContext->getBlock(), currentStmtIdx);
// NULL out these variables to cleanup.
CleanedState = NULL;
EntryNode = NULL;
currentStmt = 0;
}
void ExprEngine::ProcessInitializer(const CFGInitializer Init,
ExplodedNode *Pred) {
ExplodedNodeSet Dst;
// We don't set EntryNode and currentStmt. And we don't clean up state.
const CXXCtorInitializer *BMI = Init.getInitializer();
const StackFrameContext *stackFrame =
cast<StackFrameContext>(Pred->getLocationContext());
const CXXConstructorDecl *decl =
cast<CXXConstructorDecl>(stackFrame->getDecl());
const CXXThisRegion *thisReg = getCXXThisRegion(decl, stackFrame);
SVal thisVal = Pred->getState()->getSVal(thisReg);
if (BMI->isAnyMemberInitializer()) {
ExplodedNodeSet AfterEval;
// Evaluate the initializer.
Visit(BMI->getInit(), Pred, AfterEval);
StmtNodeBuilder Bldr(AfterEval, Dst, *currentBuilderContext);
for (ExplodedNodeSet::iterator I = AfterEval.begin(),
E = AfterEval.end(); I != E; ++I){
ExplodedNode *P = *I;
ProgramStateRef state = P->getState();
const FieldDecl *FD = BMI->getAnyMember();
SVal FieldLoc = state->getLValue(FD, thisVal);
SVal InitVal = state->getSVal(BMI->getInit(), Pred->getLocationContext());
state = state->bindLoc(FieldLoc, InitVal);
// Use a custom node building process.
PostInitializer PP(BMI, stackFrame);
// Builder automatically add the generated node to the deferred set,
// which are processed in the builder's dtor.
Bldr.generateNode(PP, P, state);
}
} else {
assert(BMI->isBaseInitializer());
// Get the base class declaration.
const CXXConstructExpr *ctorExpr = cast<CXXConstructExpr>(BMI->getInit());
// Create the base object region.
SVal baseVal =
getStoreManager().evalDerivedToBase(thisVal, ctorExpr->getType());
const MemRegion *baseReg = baseVal.getAsRegion();
assert(baseReg);
VisitCXXConstructExpr(ctorExpr, baseReg, Pred, Dst);
}
// Enqueue the new nodes onto the work list.
Engine.enqueue(Dst, currentBuilderContext->getBlock(), currentStmtIdx);
}
void ExprEngine::ProcessImplicitDtor(const CFGImplicitDtor D,
ExplodedNode *Pred) {
ExplodedNodeSet Dst;
switch (D.getKind()) {
case CFGElement::AutomaticObjectDtor:
ProcessAutomaticObjDtor(cast<CFGAutomaticObjDtor>(D), Pred, Dst);
break;
case CFGElement::BaseDtor:
ProcessBaseDtor(cast<CFGBaseDtor>(D), Pred, Dst);
break;
case CFGElement::MemberDtor:
ProcessMemberDtor(cast<CFGMemberDtor>(D), Pred, Dst);
break;
case CFGElement::TemporaryDtor:
ProcessTemporaryDtor(cast<CFGTemporaryDtor>(D), Pred, Dst);
break;
default:
llvm_unreachable("Unexpected dtor kind.");
}
// Enqueue the new nodes onto the work list.
Engine.enqueue(Dst, currentBuilderContext->getBlock(), currentStmtIdx);
}
void ExprEngine::ProcessAutomaticObjDtor(const CFGAutomaticObjDtor Dtor,
ExplodedNode *Pred,
ExplodedNodeSet &Dst) {
ProgramStateRef state = Pred->getState();
const VarDecl *varDecl = Dtor.getVarDecl();
QualType varType = varDecl->getType();
if (const ReferenceType *refType = varType->getAs<ReferenceType>())
varType = refType->getPointeeType();
const CXXRecordDecl *recordDecl = varType->getAsCXXRecordDecl();
assert(recordDecl && "get CXXRecordDecl fail");
const CXXDestructorDecl *dtorDecl = recordDecl->getDestructor();
Loc dest = state->getLValue(varDecl, Pred->getLocationContext());
VisitCXXDestructor(dtorDecl, cast<loc::MemRegionVal>(dest).getRegion(),
Dtor.getTriggerStmt(), Pred, Dst);
}
void ExprEngine::ProcessBaseDtor(const CFGBaseDtor D,
ExplodedNode *Pred, ExplodedNodeSet &Dst) {}
void ExprEngine::ProcessMemberDtor(const CFGMemberDtor D,
ExplodedNode *Pred, ExplodedNodeSet &Dst) {}
void ExprEngine::ProcessTemporaryDtor(const CFGTemporaryDtor D,
ExplodedNode *Pred,
ExplodedNodeSet &Dst) {}
void ExprEngine::Visit(const Stmt *S, ExplodedNode *Pred,
ExplodedNodeSet &DstTop) {
PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),
S->getLocStart(),
"Error evaluating statement");
ExplodedNodeSet Dst;
StmtNodeBuilder Bldr(Pred, DstTop, *currentBuilderContext);
// Expressions to ignore.
if (const Expr *Ex = dyn_cast<Expr>(S))
S = Ex->IgnoreParens();
// FIXME: add metadata to the CFG so that we can disable
// this check when we KNOW that there is no block-level subexpression.
// The motivation is that this check requires a hashtable lookup.
if (S != currentStmt && Pred->getLocationContext()->getCFG()->isBlkExpr(S))
return;
switch (S->getStmtClass()) {
// C++ and ARC stuff we don't support yet.
case Expr::ObjCIndirectCopyRestoreExprClass:
case Stmt::CXXDependentScopeMemberExprClass:
case Stmt::CXXPseudoDestructorExprClass:
case Stmt::CXXTryStmtClass:
case Stmt::CXXTypeidExprClass:
case Stmt::CXXUuidofExprClass:
case Stmt::CXXUnresolvedConstructExprClass:
case Stmt::CXXScalarValueInitExprClass:
case Stmt::DependentScopeDeclRefExprClass:
case Stmt::UnaryTypeTraitExprClass:
case Stmt::BinaryTypeTraitExprClass:
case Stmt::TypeTraitExprClass:
case Stmt::ArrayTypeTraitExprClass:
case Stmt::ExpressionTraitExprClass:
case Stmt::UnresolvedLookupExprClass:
case Stmt::UnresolvedMemberExprClass:
case Stmt::CXXNoexceptExprClass:
case Stmt::PackExpansionExprClass:
case Stmt::SubstNonTypeTemplateParmPackExprClass:
case Stmt::SEHTryStmtClass:
case Stmt::SEHExceptStmtClass:
case Stmt::LambdaExprClass:
case Stmt::SEHFinallyStmtClass: {
const ExplodedNode *node = Bldr.generateNode(S, Pred, Pred->getState(),
/* sink */ true);
Engine.addAbortedBlock(node, currentBuilderContext->getBlock());
break;
}
// We don't handle default arguments either yet, but we can fake it
// for now by just skipping them.
case Stmt::SubstNonTypeTemplateParmExprClass:
case Stmt::CXXDefaultArgExprClass:
break;
case Stmt::ParenExprClass:
llvm_unreachable("ParenExprs already handled.");
case Stmt::GenericSelectionExprClass:
llvm_unreachable("GenericSelectionExprs already handled.");
// Cases that should never be evaluated simply because they shouldn't
// appear in the CFG.
case Stmt::BreakStmtClass:
case Stmt::CaseStmtClass:
case Stmt::CompoundStmtClass:
case Stmt::ContinueStmtClass:
case Stmt::CXXForRangeStmtClass:
case Stmt::DefaultStmtClass:
case Stmt::DoStmtClass:
case Stmt::ForStmtClass:
case Stmt::GotoStmtClass:
case Stmt::IfStmtClass:
case Stmt::IndirectGotoStmtClass:
case Stmt::LabelStmtClass:
case Stmt::NoStmtClass:
case Stmt::NullStmtClass:
case Stmt::SwitchStmtClass:
case Stmt::WhileStmtClass:
case Expr::MSDependentExistsStmtClass:
llvm_unreachable("Stmt should not be in analyzer evaluation loop");
case Stmt::GNUNullExprClass: {
// GNU __null is a pointer-width integer, not an actual pointer.
ProgramStateRef state = Pred->getState();
state = state->BindExpr(S, Pred->getLocationContext(),
svalBuilder.makeIntValWithPtrWidth(0, false));
Bldr.generateNode(S, Pred, state);
break;
}
case Stmt::ObjCAtSynchronizedStmtClass:
Bldr.takeNodes(Pred);
VisitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(S), Pred, Dst);
Bldr.addNodes(Dst);
break;
// FIXME.
case Stmt::ObjCSubscriptRefExprClass:
break;
case Stmt::ObjCPropertyRefExprClass:
// Implicitly handled by Environment::getSVal().
break;
case Stmt::ImplicitValueInitExprClass: {
ProgramStateRef state = Pred->getState();
QualType ty = cast<ImplicitValueInitExpr>(S)->getType();
SVal val = svalBuilder.makeZeroVal(ty);
Bldr.generateNode(S, Pred, state->BindExpr(S, Pred->getLocationContext(),
val));
break;
}
case Stmt::ExprWithCleanupsClass:
Bldr.takeNodes(Pred);
Visit(cast<ExprWithCleanups>(S)->getSubExpr(), Pred, Dst);
Bldr.addNodes(Dst);
break;
// Cases not handled yet; but will handle some day.
case Stmt::DesignatedInitExprClass:
case Stmt::ExtVectorElementExprClass:
case Stmt::ImaginaryLiteralClass:
case Stmt::ObjCAtCatchStmtClass:
case Stmt::ObjCAtFinallyStmtClass:
case Stmt::ObjCAtTryStmtClass:
case Stmt::ObjCAutoreleasePoolStmtClass:
case Stmt::ObjCEncodeExprClass:
case Stmt::ObjCIsaExprClass:
case Stmt::ObjCProtocolExprClass:
case Stmt::ObjCSelectorExprClass:
case Expr::ObjCNumericLiteralClass:
case Stmt::ParenListExprClass:
case Stmt::PredefinedExprClass:
case Stmt::ShuffleVectorExprClass:
case Stmt::VAArgExprClass:
case Stmt::CUDAKernelCallExprClass:
case Stmt::OpaqueValueExprClass:
case Stmt::AsTypeExprClass:
case Stmt::AtomicExprClass:
// Fall through.
// Currently all handling of 'throw' just falls to the CFG. We
// can consider doing more if necessary.
case Stmt::CXXThrowExprClass:
// Fall through.
// Cases we intentionally don't evaluate, since they don't need
// to be explicitly evaluated.
case Stmt::AddrLabelExprClass:
case Stmt::IntegerLiteralClass:
case Stmt::CharacterLiteralClass:
case Stmt::CXXBoolLiteralExprClass:
case Stmt::ObjCBoolLiteralExprClass:
case Stmt::FloatingLiteralClass:
case Stmt::SizeOfPackExprClass:
case Stmt::StringLiteralClass:
case Stmt::ObjCStringLiteralClass:
case Stmt::CXXBindTemporaryExprClass:
case Stmt::CXXNullPtrLiteralExprClass: {
Bldr.takeNodes(Pred);
ExplodedNodeSet preVisit;
getCheckerManager().runCheckersForPreStmt(preVisit, Pred, S, *this);
getCheckerManager().runCheckersForPostStmt(Dst, preVisit, S, *this);
Bldr.addNodes(Dst);
break;
}
case Expr::ObjCArrayLiteralClass:
case Expr::ObjCDictionaryLiteralClass: {
Bldr.takeNodes(Pred);
ExplodedNodeSet preVisit;
getCheckerManager().runCheckersForPreStmt(preVisit, Pred, S, *this);
// FIXME: explicitly model with a region and the actual contents
// of the container. For now, conjure a symbol.
ExplodedNodeSet Tmp;
StmtNodeBuilder Bldr2(preVisit, Tmp, *currentBuilderContext);
for (ExplodedNodeSet::iterator it = preVisit.begin(), et = preVisit.end();
it != et; ++it) {
ExplodedNode *N = *it;
const Expr *Ex = cast<Expr>(S);
QualType resultType = Ex->getType();
const LocationContext *LCtx = N->getLocationContext();
SVal result =
svalBuilder.getConjuredSymbolVal(0, Ex, LCtx, resultType,
currentBuilderContext->getCurrentBlockCount());
ProgramStateRef state = N->getState()->BindExpr(Ex, LCtx, result);
Bldr2.generateNode(S, N, state);
}
getCheckerManager().runCheckersForPostStmt(Dst, Tmp, S, *this);
Bldr.addNodes(Dst);
break;
}
case Stmt::ArraySubscriptExprClass:
Bldr.takeNodes(Pred);
VisitLvalArraySubscriptExpr(cast<ArraySubscriptExpr>(S), Pred, Dst);
Bldr.addNodes(Dst);
break;
case Stmt::AsmStmtClass:
Bldr.takeNodes(Pred);
VisitAsmStmt(cast<AsmStmt>(S), Pred, Dst);
Bldr.addNodes(Dst);
break;
case Stmt::BlockExprClass:
Bldr.takeNodes(Pred);
VisitBlockExpr(cast<BlockExpr>(S), Pred, Dst);
Bldr.addNodes(Dst);
break;
case Stmt::BinaryOperatorClass: {
const BinaryOperator* B = cast<BinaryOperator>(S);
if (B->isLogicalOp()) {
Bldr.takeNodes(Pred);
VisitLogicalExpr(B, Pred, Dst);
Bldr.addNodes(Dst);
break;
}
else if (B->getOpcode() == BO_Comma) {
ProgramStateRef state = Pred->getState();
Bldr.generateNode(B, Pred,
state->BindExpr(B, Pred->getLocationContext(),
state->getSVal(B->getRHS(),
Pred->getLocationContext())));
break;
}
Bldr.takeNodes(Pred);
if (AMgr.shouldEagerlyAssume() &&
(B->isRelationalOp() || B->isEqualityOp())) {
ExplodedNodeSet Tmp;
VisitBinaryOperator(cast<BinaryOperator>(S), Pred, Tmp);
evalEagerlyAssume(Dst, Tmp, cast<Expr>(S));
}
else
VisitBinaryOperator(cast<BinaryOperator>(S), Pred, Dst);
Bldr.addNodes(Dst);
break;
}
case Stmt::CallExprClass:
case Stmt::CXXOperatorCallExprClass:
case Stmt::CXXMemberCallExprClass:
case Stmt::UserDefinedLiteralClass: {
Bldr.takeNodes(Pred);
VisitCallExpr(cast<CallExpr>(S), Pred, Dst);
Bldr.addNodes(Dst);
break;
}
case Stmt::CXXCatchStmtClass: {
Bldr.takeNodes(Pred);
VisitCXXCatchStmt(cast<CXXCatchStmt>(S), Pred, Dst);
Bldr.addNodes(Dst);
break;
}
case Stmt::CXXTemporaryObjectExprClass:
case Stmt::CXXConstructExprClass: {
const CXXConstructExpr *C = cast<CXXConstructExpr>(S);
// For block-level CXXConstructExpr, we don't have a destination region.
// Let VisitCXXConstructExpr() create one.
Bldr.takeNodes(Pred);
VisitCXXConstructExpr(C, 0, Pred, Dst);
Bldr.addNodes(Dst);
break;
}
case Stmt::CXXNewExprClass: {
Bldr.takeNodes(Pred);
const CXXNewExpr *NE = cast<CXXNewExpr>(S);
VisitCXXNewExpr(NE, Pred, Dst);
Bldr.addNodes(Dst);
break;
}
case Stmt::CXXDeleteExprClass: {
Bldr.takeNodes(Pred);
const CXXDeleteExpr *CDE = cast<CXXDeleteExpr>(S);
VisitCXXDeleteExpr(CDE, Pred, Dst);
Bldr.addNodes(Dst);
break;
}
// FIXME: ChooseExpr is really a constant. We need to fix
// the CFG do not model them as explicit control-flow.
case Stmt::ChooseExprClass: { // __builtin_choose_expr
Bldr.takeNodes(Pred);
const ChooseExpr *C = cast<ChooseExpr>(S);
VisitGuardedExpr(C, C->getLHS(), C->getRHS(), Pred, Dst);
Bldr.addNodes(Dst);
break;
}
case Stmt::CompoundAssignOperatorClass:
Bldr.takeNodes(Pred);
VisitBinaryOperator(cast<BinaryOperator>(S), Pred, Dst);
Bldr.addNodes(Dst);
break;
case Stmt::CompoundLiteralExprClass:
Bldr.takeNodes(Pred);
VisitCompoundLiteralExpr(cast<CompoundLiteralExpr>(S), Pred, Dst);
Bldr.addNodes(Dst);
break;
case Stmt::BinaryConditionalOperatorClass:
case Stmt::ConditionalOperatorClass: { // '?' operator
Bldr.takeNodes(Pred);
const AbstractConditionalOperator *C
= cast<AbstractConditionalOperator>(S);
VisitGuardedExpr(C, C->getTrueExpr(), C->getFalseExpr(), Pred, Dst);
Bldr.addNodes(Dst);
break;
}
case Stmt::CXXThisExprClass:
Bldr.takeNodes(Pred);
VisitCXXThisExpr(cast<CXXThisExpr>(S), Pred, Dst);
Bldr.addNodes(Dst);
break;
case Stmt::DeclRefExprClass: {
Bldr.takeNodes(Pred);
const DeclRefExpr *DE = cast<DeclRefExpr>(S);
VisitCommonDeclRefExpr(DE, DE->getDecl(), Pred, Dst);
Bldr.addNodes(Dst);
break;
}
case Stmt::DeclStmtClass:
Bldr.takeNodes(Pred);
VisitDeclStmt(cast<DeclStmt>(S), Pred, Dst);
Bldr.addNodes(Dst);
break;
case Stmt::ImplicitCastExprClass:
case Stmt::CStyleCastExprClass:
case Stmt::CXXStaticCastExprClass:
case Stmt::CXXDynamicCastExprClass:
case Stmt::CXXReinterpretCastExprClass:
case Stmt::CXXConstCastExprClass:
case Stmt::CXXFunctionalCastExprClass:
case Stmt::ObjCBridgedCastExprClass: {
Bldr.takeNodes(Pred);
const CastExpr *C = cast<CastExpr>(S);
// Handle the previsit checks.
ExplodedNodeSet dstPrevisit;
getCheckerManager().runCheckersForPreStmt(dstPrevisit, Pred, C, *this);
// Handle the expression itself.
ExplodedNodeSet dstExpr;
for (ExplodedNodeSet::iterator i = dstPrevisit.begin(),
e = dstPrevisit.end(); i != e ; ++i) {
VisitCast(C, C->getSubExpr(), *i, dstExpr);
}
// Handle the postvisit checks.
getCheckerManager().runCheckersForPostStmt(Dst, dstExpr, C, *this);
Bldr.addNodes(Dst);
break;
}
case Expr::MaterializeTemporaryExprClass: {
Bldr.takeNodes(Pred);
const MaterializeTemporaryExpr *Materialize
= cast<MaterializeTemporaryExpr>(S);
if (!Materialize->getType()->isRecordType())
CreateCXXTemporaryObject(Materialize, Pred, Dst);
else
Visit(Materialize->GetTemporaryExpr(), Pred, Dst);
Bldr.addNodes(Dst);
break;
}
case Stmt::InitListExprClass:
Bldr.takeNodes(Pred);
VisitInitListExpr(cast<InitListExpr>(S), Pred, Dst);
Bldr.addNodes(Dst);
break;
case Stmt::MemberExprClass:
Bldr.takeNodes(Pred);
VisitMemberExpr(cast<MemberExpr>(S), Pred, Dst);
Bldr.addNodes(Dst);
break;
case Stmt::ObjCIvarRefExprClass:
Bldr.takeNodes(Pred);
VisitLvalObjCIvarRefExpr(cast<ObjCIvarRefExpr>(S), Pred, Dst);
Bldr.addNodes(Dst);
break;
case Stmt::ObjCForCollectionStmtClass:
Bldr.takeNodes(Pred);
VisitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(S), Pred, Dst);
Bldr.addNodes(Dst);
break;
case Stmt::ObjCMessageExprClass: {
Bldr.takeNodes(Pred);
// Is this a property access?
const ParentMap &PM = Pred->getLocationContext()->getParentMap();
const ObjCMessageExpr *ME = cast<ObjCMessageExpr>(S);
bool evaluated = false;
if (const PseudoObjectExpr *PO =
dyn_cast_or_null<PseudoObjectExpr>(PM.getParent(S))) {
const Expr *syntactic = PO->getSyntacticForm();
if (const ObjCPropertyRefExpr *PR =
dyn_cast<ObjCPropertyRefExpr>(syntactic)) {
bool isSetter = ME->getNumArgs() > 0;
VisitObjCMessage(ObjCMessage(ME, PR, isSetter), Pred, Dst);
evaluated = true;
}
else if (isa<BinaryOperator>(syntactic)) {
VisitObjCMessage(ObjCMessage(ME, 0, true), Pred, Dst);
}
}
if (!evaluated)
VisitObjCMessage(ME, Pred, Dst);
Bldr.addNodes(Dst);
break;
}
case Stmt::ObjCAtThrowStmtClass: {
// FIXME: This is not complete. We basically treat @throw as
// an abort.
Bldr.generateNode(S, Pred, Pred->getState());
break;
}
case Stmt::ReturnStmtClass:
Bldr.takeNodes(Pred);
VisitReturnStmt(cast<ReturnStmt>(S), Pred, Dst);
Bldr.addNodes(Dst);
break;
case Stmt::OffsetOfExprClass:
Bldr.takeNodes(Pred);
VisitOffsetOfExpr(cast<OffsetOfExpr>(S), Pred, Dst);
Bldr.addNodes(Dst);
break;
case Stmt::UnaryExprOrTypeTraitExprClass:
Bldr.takeNodes(Pred);
VisitUnaryExprOrTypeTraitExpr(cast<UnaryExprOrTypeTraitExpr>(S),
Pred, Dst);
Bldr.addNodes(Dst);
break;
case Stmt::StmtExprClass: {
const StmtExpr *SE = cast<StmtExpr>(S);
if (SE->getSubStmt()->body_empty()) {
// Empty statement expression.
assert(SE->getType() == getContext().VoidTy
&& "Empty statement expression must have void type.");
break;
}
if (Expr *LastExpr = dyn_cast<Expr>(*SE->getSubStmt()->body_rbegin())) {
ProgramStateRef state = Pred->getState();
Bldr.generateNode(SE, Pred,
state->BindExpr(SE, Pred->getLocationContext(),
state->getSVal(LastExpr,
Pred->getLocationContext())));
}
break;
}
case Stmt::UnaryOperatorClass: {
Bldr.takeNodes(Pred);
const UnaryOperator *U = cast<UnaryOperator>(S);
if (AMgr.shouldEagerlyAssume() && (U->getOpcode() == UO_LNot)) {
ExplodedNodeSet Tmp;
VisitUnaryOperator(U, Pred, Tmp);
evalEagerlyAssume(Dst, Tmp, U);
}
else
VisitUnaryOperator(U, Pred, Dst);
Bldr.addNodes(Dst);
break;
}
case Stmt::PseudoObjectExprClass: {
Bldr.takeNodes(Pred);
ProgramStateRef state = Pred->getState();
const PseudoObjectExpr *PE = cast<PseudoObjectExpr>(S);
if (const Expr *Result = PE->getResultExpr()) {
SVal V = state->getSVal(Result, Pred->getLocationContext());
Bldr.generateNode(S, Pred,
state->BindExpr(S, Pred->getLocationContext(), V));
}
else
Bldr.generateNode(S, Pred,
state->BindExpr(S, Pred->getLocationContext(),
UnknownVal()));
Bldr.addNodes(Dst);
break;
}
}
}
/// Block entrance. (Update counters).
void ExprEngine::processCFGBlockEntrance(NodeBuilderWithSinks &nodeBuilder) {
// FIXME: Refactor this into a checker.
ExplodedNode *pred = nodeBuilder.getContext().getPred();
if (nodeBuilder.getContext().getCurrentBlockCount() >= AMgr.getMaxVisit()) {
static SimpleProgramPointTag tag("ExprEngine : Block count exceeded");
nodeBuilder.generateNode(pred->getState(), pred, &tag, true);
}
}
//===----------------------------------------------------------------------===//
// Branch processing.
//===----------------------------------------------------------------------===//
ProgramStateRef ExprEngine::MarkBranch(ProgramStateRef state,
const Stmt *Terminator,
const LocationContext *LCtx,
bool branchTaken) {
switch (Terminator->getStmtClass()) {
default:
return state;
case Stmt::BinaryOperatorClass: { // '&&' and '||'
const BinaryOperator* B = cast<BinaryOperator>(Terminator);
BinaryOperator::Opcode Op = B->getOpcode();
assert (Op == BO_LAnd || Op == BO_LOr);
// For &&, if we take the true branch, then the value of the whole
// expression is that of the RHS expression.
//
// For ||, if we take the false branch, then the value of the whole
// expression is that of the RHS expression.
const Expr *Ex = (Op == BO_LAnd && branchTaken) ||
(Op == BO_LOr && !branchTaken)
? B->getRHS() : B->getLHS();
return state->BindExpr(B, LCtx, UndefinedVal(Ex));
}
case Stmt::BinaryConditionalOperatorClass:
case Stmt::ConditionalOperatorClass: { // ?:
const AbstractConditionalOperator* C
= cast<AbstractConditionalOperator>(Terminator);
// For ?, if branchTaken == true then the value is either the LHS or
// the condition itself. (GNU extension).
const Expr *Ex;
if (branchTaken)
Ex = C->getTrueExpr();
else
Ex = C->getFalseExpr();
return state->BindExpr(C, LCtx, UndefinedVal(Ex));
}
case Stmt::ChooseExprClass: { // ?:
const ChooseExpr *C = cast<ChooseExpr>(Terminator);
const Expr *Ex = branchTaken ? C->getLHS() : C->getRHS();
return state->BindExpr(C, LCtx, UndefinedVal(Ex));
}
}
}
/// RecoverCastedSymbol - A helper function for ProcessBranch that is used
/// to try to recover some path-sensitivity for casts of symbolic
/// integers that promote their values (which are currently not tracked well).
/// This function returns the SVal bound to Condition->IgnoreCasts if all the
// cast(s) did was sign-extend the original value.
static SVal RecoverCastedSymbol(ProgramStateManager& StateMgr,
ProgramStateRef state,
const Stmt *Condition,
const LocationContext *LCtx,
ASTContext &Ctx) {
const Expr *Ex = dyn_cast<Expr>(Condition);
if (!Ex)
return UnknownVal();
uint64_t bits = 0;
bool bitsInit = false;
while (const CastExpr *CE = dyn_cast<CastExpr>(Ex)) {
QualType T = CE->getType();
if (!T->isIntegerType())
return UnknownVal();
uint64_t newBits = Ctx.getTypeSize(T);
if (!bitsInit || newBits < bits) {
bitsInit = true;
bits = newBits;
}
Ex = CE->getSubExpr();
}
// We reached a non-cast. Is it a symbolic value?
QualType T = Ex->getType();
if (!bitsInit || !T->isIntegerType() || Ctx.getTypeSize(T) > bits)
return UnknownVal();
return state->getSVal(Ex, LCtx);
}
void ExprEngine::processBranch(const Stmt *Condition, const Stmt *Term,
NodeBuilderContext& BldCtx,
ExplodedNode *Pred,
ExplodedNodeSet &Dst,
const CFGBlock *DstT,
const CFGBlock *DstF) {
currentBuilderContext = &BldCtx;
// Check for NULL conditions; e.g. "for(;;)"
if (!Condition) {
BranchNodeBuilder NullCondBldr(Pred, Dst, BldCtx, DstT, DstF);
NullCondBldr.markInfeasible(false);
NullCondBldr.generateNode(Pred->getState(), true, Pred);
return;
}
PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),
Condition->getLocStart(),
"Error evaluating branch");
ExplodedNodeSet CheckersOutSet;
getCheckerManager().runCheckersForBranchCondition(Condition, CheckersOutSet,
Pred, *this);
// We generated only sinks.
if (CheckersOutSet.empty())
return;
BranchNodeBuilder builder(CheckersOutSet, Dst, BldCtx, DstT, DstF);
for (NodeBuilder::iterator I = CheckersOutSet.begin(),
E = CheckersOutSet.end(); E != I; ++I) {
ExplodedNode *PredI = *I;
if (PredI->isSink())
continue;
ProgramStateRef PrevState = Pred->getState();
SVal X = PrevState->getSVal(Condition, Pred->getLocationContext());
if (X.isUnknownOrUndef()) {
// Give it a chance to recover from unknown.
if (const Expr *Ex = dyn_cast<Expr>(Condition)) {
if (Ex->getType()->isIntegerType()) {
// Try to recover some path-sensitivity. Right now casts of symbolic
// integers that promote their values are currently not tracked well.
// If 'Condition' is such an expression, try and recover the
// underlying value and use that instead.
SVal recovered = RecoverCastedSymbol(getStateManager(),
PrevState, Condition,
Pred->getLocationContext(),
getContext());
if (!recovered.isUnknown()) {
X = recovered;
}
}
}
}
const LocationContext *LCtx = PredI->getLocationContext();
// If the condition is still unknown, give up.
if (X.isUnknownOrUndef()) {
builder.generateNode(MarkBranch(PrevState, Term, LCtx, true),
true, PredI);
builder.generateNode(MarkBranch(PrevState, Term, LCtx, false),
false, PredI);
continue;
}
DefinedSVal V = cast<DefinedSVal>(X);
// Process the true branch.
if (builder.isFeasible(true)) {
if (ProgramStateRef state = PrevState->assume(V, true))
builder.generateNode(MarkBranch(state, Term, LCtx, true),
true, PredI);
else
builder.markInfeasible(true);
}
// Process the false branch.
if (builder.isFeasible(false)) {
if (ProgramStateRef state = PrevState->assume(V, false))
builder.generateNode(MarkBranch(state, Term, LCtx, false),
false, PredI);
else
builder.markInfeasible(false);
}
}
currentBuilderContext = 0;
}
/// processIndirectGoto - Called by CoreEngine. Used to generate successor
/// nodes by processing the 'effects' of a computed goto jump.
void ExprEngine::processIndirectGoto(IndirectGotoNodeBuilder &builder) {
ProgramStateRef state = builder.getState();
SVal V = state->getSVal(builder.getTarget(), builder.getLocationContext());
// Three possibilities:
//
// (1) We know the computed label.
// (2) The label is NULL (or some other constant), or Undefined.
// (3) We have no clue about the label. Dispatch to all targets.
//
typedef IndirectGotoNodeBuilder::iterator iterator;
if (isa<loc::GotoLabel>(V)) {
const LabelDecl *L = cast<loc::GotoLabel>(V).getLabel();
for (iterator I = builder.begin(), E = builder.end(); I != E; ++I) {
if (I.getLabel() == L) {
builder.generateNode(I, state);
return;
}
}
llvm_unreachable("No block with label.");
}
if (isa<loc::ConcreteInt>(V) || isa<UndefinedVal>(V)) {
// Dispatch to the first target and mark it as a sink.
//ExplodedNode* N = builder.generateNode(builder.begin(), state, true);
// FIXME: add checker visit.
// UndefBranches.insert(N);
return;
}
// This is really a catch-all. We don't support symbolics yet.
// FIXME: Implement dispatch for symbolic pointers.
for (iterator I=builder.begin(), E=builder.end(); I != E; ++I)
builder.generateNode(I, state);
}
/// ProcessEndPath - Called by CoreEngine. Used to generate end-of-path
/// nodes when the control reaches the end of a function.
void ExprEngine::processEndOfFunction(NodeBuilderContext& BC) {
StateMgr.EndPath(BC.Pred->getState());
ExplodedNodeSet Dst;
getCheckerManager().runCheckersForEndPath(BC, Dst, *this);
Engine.enqueueEndOfFunction(Dst);
}
/// ProcessSwitch - Called by CoreEngine. Used to generate successor
/// nodes by processing the 'effects' of a switch statement.
void ExprEngine::processSwitch(SwitchNodeBuilder& builder) {
typedef SwitchNodeBuilder::iterator iterator;
ProgramStateRef state = builder.getState();
const Expr *CondE = builder.getCondition();
SVal CondV_untested = state->getSVal(CondE, builder.getLocationContext());
if (CondV_untested.isUndef()) {
//ExplodedNode* N = builder.generateDefaultCaseNode(state, true);
// FIXME: add checker
//UndefBranches.insert(N);
return;
}
DefinedOrUnknownSVal CondV = cast<DefinedOrUnknownSVal>(CondV_untested);
ProgramStateRef DefaultSt = state;
iterator I = builder.begin(), EI = builder.end();
bool defaultIsFeasible = I == EI;
for ( ; I != EI; ++I) {
// Successor may be pruned out during CFG construction.
if (!I.getBlock())
continue;
const CaseStmt *Case = I.getCase();
// Evaluate the LHS of the case value.
llvm::APSInt V1 = Case->getLHS()->EvaluateKnownConstInt(getContext());
assert(V1.getBitWidth() == getContext().getTypeSize(CondE->getType()));
// Get the RHS of the case, if it exists.
llvm::APSInt V2;
if (const Expr *E = Case->getRHS())
V2 = E->EvaluateKnownConstInt(getContext());
else
V2 = V1;
// FIXME: Eventually we should replace the logic below with a range
// comparison, rather than concretize the values within the range.
// This should be easy once we have "ranges" for NonLVals.
do {
nonloc::ConcreteInt CaseVal(getBasicVals().getValue(V1));
DefinedOrUnknownSVal Res = svalBuilder.evalEQ(DefaultSt ? DefaultSt : state,
CondV, CaseVal);
// Now "assume" that the case matches.
if (ProgramStateRef stateNew = state->assume(Res, true)) {
builder.generateCaseStmtNode(I, stateNew);
// If CondV evaluates to a constant, then we know that this
// is the *only* case that we can take, so stop evaluating the
// others.
if (isa<nonloc::ConcreteInt>(CondV))
return;
}
// Now "assume" that the case doesn't match. Add this state
// to the default state (if it is feasible).
if (DefaultSt) {
if (ProgramStateRef stateNew = DefaultSt->assume(Res, false)) {
defaultIsFeasible = true;
DefaultSt = stateNew;
}
else {
defaultIsFeasible = false;
DefaultSt = NULL;
}
}
// Concretize the next value in the range.
if (V1 == V2)
break;
++V1;
assert (V1 <= V2);
} while (true);
}
if (!defaultIsFeasible)
return;
// If we have switch(enum value), the default branch is not
// feasible if all of the enum constants not covered by 'case:' statements
// are not feasible values for the switch condition.
//
// Note that this isn't as accurate as it could be. Even if there isn't
// a case for a particular enum value as long as that enum value isn't
// feasible then it shouldn't be considered for making 'default:' reachable.
const SwitchStmt *SS = builder.getSwitch();
const Expr *CondExpr = SS->getCond()->IgnoreParenImpCasts();
if (CondExpr->getType()->getAs<EnumType>()) {
if (SS->isAllEnumCasesCovered())
return;
}
builder.generateDefaultCaseNode(DefaultSt);
}
//===----------------------------------------------------------------------===//
// Transfer functions: Loads and stores.
//===----------------------------------------------------------------------===//
void ExprEngine::VisitCommonDeclRefExpr(const Expr *Ex, const NamedDecl *D,
ExplodedNode *Pred,
ExplodedNodeSet &Dst) {
StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext);
ProgramStateRef state = Pred->getState();
const LocationContext *LCtx = Pred->getLocationContext();
if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
assert(Ex->isLValue());
SVal V = state->getLValue(VD, Pred->getLocationContext());
// For references, the 'lvalue' is the pointer address stored in the
// reference region.
if (VD->getType()->isReferenceType()) {
if (const MemRegion *R = V.getAsRegion())
V = state->getSVal(R);
else
V = UnknownVal();
}
Bldr.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, V), false, 0,
ProgramPoint::PostLValueKind);
return;
}
if (const EnumConstantDecl *ED = dyn_cast<EnumConstantDecl>(D)) {
assert(!Ex->isLValue());
SVal V = svalBuilder.makeIntVal(ED->getInitVal());
Bldr.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, V));
return;
}
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
SVal V = svalBuilder.getFunctionPointer(FD);
Bldr.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, V), false, 0,
ProgramPoint::PostLValueKind);
return;
}
assert (false &&
"ValueDecl support for this ValueDecl not implemented.");
}
/// VisitArraySubscriptExpr - Transfer function for array accesses
void ExprEngine::VisitLvalArraySubscriptExpr(const ArraySubscriptExpr *A,
ExplodedNode *Pred,
ExplodedNodeSet &Dst){
const Expr *Base = A->getBase()->IgnoreParens();
const Expr *Idx = A->getIdx()->IgnoreParens();
ExplodedNodeSet checkerPreStmt;
getCheckerManager().runCheckersForPreStmt(checkerPreStmt, Pred, A, *this);
StmtNodeBuilder Bldr(checkerPreStmt, Dst, *currentBuilderContext);
for (ExplodedNodeSet::iterator it = checkerPreStmt.begin(),
ei = checkerPreStmt.end(); it != ei; ++it) {
const LocationContext *LCtx = (*it)->getLocationContext();
ProgramStateRef state = (*it)->getState();
SVal V = state->getLValue(A->getType(),
state->getSVal(Idx, LCtx),
state->getSVal(Base, LCtx));
assert(A->isLValue());
Bldr.generateNode(A, *it, state->BindExpr(A, LCtx, V),
false, 0, ProgramPoint::PostLValueKind);
}
}
/// VisitMemberExpr - Transfer function for member expressions.
void ExprEngine::VisitMemberExpr(const MemberExpr *M, ExplodedNode *Pred,
ExplodedNodeSet &TopDst) {
StmtNodeBuilder Bldr(Pred, TopDst, *currentBuilderContext);
ExplodedNodeSet Dst;
Decl *member = M->getMemberDecl();
if (VarDecl *VD = dyn_cast<VarDecl>(member)) {
assert(M->isLValue());
Bldr.takeNodes(Pred);
VisitCommonDeclRefExpr(M, VD, Pred, Dst);
Bldr.addNodes(Dst);
return;
}
FieldDecl *field = dyn_cast<FieldDecl>(member);
if (!field) // FIXME: skipping member expressions for non-fields
return;
Expr *baseExpr = M->getBase()->IgnoreParens();
ProgramStateRef state = Pred->getState();
const LocationContext *LCtx = Pred->getLocationContext();
SVal baseExprVal = state->getSVal(baseExpr, Pred->getLocationContext());
if (isa<nonloc::LazyCompoundVal>(baseExprVal) ||
isa<nonloc::CompoundVal>(baseExprVal) ||
// FIXME: This can originate by conjuring a symbol for an unknown
// temporary struct object, see test/Analysis/fields.c:
// (p = getit()).x
isa<nonloc::SymbolVal>(baseExprVal)) {
Bldr.generateNode(M, Pred, state->BindExpr(M, LCtx, UnknownVal()));
return;
}
// FIXME: Should we insert some assumption logic in here to determine
// if "Base" is a valid piece of memory? Before we put this assumption
// later when using FieldOffset lvals (which we no longer have).
// For all other cases, compute an lvalue.
SVal L = state->getLValue(field, baseExprVal);
if (M->isLValue())
Bldr.generateNode(M, Pred, state->BindExpr(M, LCtx, L), false, 0,
ProgramPoint::PostLValueKind);
else {
Bldr.takeNodes(Pred);
evalLoad(Dst, M, Pred, state, L);
Bldr.addNodes(Dst);
}
}
/// evalBind - Handle the semantics of binding a value to a specific location.
/// This method is used by evalStore and (soon) VisitDeclStmt, and others.
void ExprEngine::evalBind(ExplodedNodeSet &Dst, const Stmt *StoreE,
ExplodedNode *Pred,
SVal location, SVal Val, bool atDeclInit,
ProgramPoint::Kind PointKind) {
// Do a previsit of the bind.
ExplodedNodeSet CheckedSet;
getCheckerManager().runCheckersForBind(CheckedSet, Pred, location, Val,
StoreE, *this, PointKind);
// TODO:AZ Remove TmpDst after NB refactoring is done.
ExplodedNodeSet TmpDst;
StmtNodeBuilder Bldr(CheckedSet, TmpDst, *currentBuilderContext);
for (ExplodedNodeSet::iterator I = CheckedSet.begin(), E = CheckedSet.end();
I!=E; ++I) {
ProgramStateRef state = (*I)->getState();
if (atDeclInit) {
const VarRegion *VR =
cast<VarRegion>(cast<loc::MemRegionVal>(location).getRegion());
state = state->bindDecl(VR, Val);
} else {
state = state->bindLoc(location, Val);
}
Bldr.generateNode(StoreE, *I, state, false, 0, PointKind);
}
Dst.insert(TmpDst);
}
/// evalStore - Handle the semantics of a store via an assignment.
/// @param Dst The node set to store generated state nodes
/// @param AssignE The assignment expression if the store happens in an
/// assignment.
/// @param LocatioinE The location expression that is stored to.
/// @param state The current simulation state
/// @param location The location to store the value
/// @param Val The value to be stored
void ExprEngine::evalStore(ExplodedNodeSet &Dst, const Expr *AssignE,
const Expr *LocationE,
ExplodedNode *Pred,
ProgramStateRef state, SVal location, SVal Val,
const ProgramPointTag *tag) {
// Proceed with the store. We use AssignE as the anchor for the PostStore
// ProgramPoint if it is non-NULL, and LocationE otherwise.
const Expr *StoreE = AssignE ? AssignE : LocationE;
if (isa<loc::ObjCPropRef>(location)) {
assert(false);
}
// Evaluate the location (checks for bad dereferences).
ExplodedNodeSet Tmp;
evalLocation(Tmp, LocationE, Pred, state, location, tag, false);
if (Tmp.empty())
return;
if (location.isUndef())
return;
for (ExplodedNodeSet::iterator NI=Tmp.begin(), NE=Tmp.end(); NI!=NE; ++NI)
evalBind(Dst, StoreE, *NI, location, Val, false,
ProgramPoint::PostStoreKind);
}
void ExprEngine::evalLoad(ExplodedNodeSet &Dst, const Expr *Ex,
ExplodedNode *Pred,
ProgramStateRef state, SVal location,
const ProgramPointTag *tag, QualType LoadTy) {
assert(!isa<NonLoc>(location) && "location cannot be a NonLoc.");
if (isa<loc::ObjCPropRef>(location)) {
assert(false);
}
// Are we loading from a region? This actually results in two loads; one
// to fetch the address of the referenced value and one to fetch the
// referenced value.
if (const TypedValueRegion *TR =
dyn_cast_or_null<TypedValueRegion>(location.getAsRegion())) {
QualType ValTy = TR->getValueType();
if (const ReferenceType *RT = ValTy->getAs<ReferenceType>()) {
static SimpleProgramPointTag
loadReferenceTag("ExprEngine : Load Reference");
ExplodedNodeSet Tmp;
evalLoadCommon(Tmp, Ex, Pred, state, location, &loadReferenceTag,
getContext().getPointerType(RT->getPointeeType()));
// Perform the load from the referenced value.
for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end() ; I!=E; ++I) {
state = (*I)->getState();
location = state->getSVal(Ex, (*I)->getLocationContext());
evalLoadCommon(Dst, Ex, *I, state, location, tag, LoadTy);
}
return;
}
}
evalLoadCommon(Dst, Ex, Pred, state, location, tag, LoadTy);
}
void ExprEngine::evalLoadCommon(ExplodedNodeSet &Dst, const Expr *Ex,
ExplodedNode *Pred,
ProgramStateRef state, SVal location,
const ProgramPointTag *tag, QualType LoadTy) {
// Evaluate the location (checks for bad dereferences).
ExplodedNodeSet Tmp;
evalLocation(Tmp, Ex, Pred, state, location, tag, true);
if (Tmp.empty())
return;
StmtNodeBuilder Bldr(Tmp, Dst, *currentBuilderContext);
if (location.isUndef())
return;
// Proceed with the load.
for (ExplodedNodeSet::iterator NI=Tmp.begin(), NE=Tmp.end(); NI!=NE; ++NI) {
state = (*NI)->getState();
const LocationContext *LCtx = (*NI)->getLocationContext();
if (location.isUnknown()) {
// This is important. We must nuke the old binding.
Bldr.generateNode(Ex, *NI, state->BindExpr(Ex, LCtx, UnknownVal()),
false, tag, ProgramPoint::PostLoadKind);
}
else {
if (LoadTy.isNull())
LoadTy = Ex->getType();
SVal V = state->getSVal(cast<Loc>(location), LoadTy);
Bldr.generateNode(Ex, *NI, state->bindExprAndLocation(Ex, LCtx,
location, V),
false, tag, ProgramPoint::PostLoadKind);
}
}
}
void ExprEngine::evalLocation(ExplodedNodeSet &Dst, const Stmt *S,
ExplodedNode *Pred,
ProgramStateRef state, SVal location,
const ProgramPointTag *tag, bool isLoad) {
StmtNodeBuilder BldrTop(Pred, Dst, *currentBuilderContext);
// Early checks for performance reason.
if (location.isUnknown()) {
return;
}
ExplodedNodeSet Src;
BldrTop.takeNodes(Pred);
StmtNodeBuilder Bldr(Pred, Src, *currentBuilderContext);
if (Pred->getState() != state) {
// Associate this new state with an ExplodedNode.
// FIXME: If I pass null tag, the graph is incorrect, e.g for
// int *p;
// p = 0;
// *p = 0xDEADBEEF;
// "p = 0" is not noted as "Null pointer value stored to 'p'" but
// instead "int *p" is noted as
// "Variable 'p' initialized to a null pointer value"
// FIXME: why is 'tag' not used instead of etag?
static SimpleProgramPointTag etag("ExprEngine: Location");
Bldr.generateNode(S, Pred, state, false, &etag);
}
ExplodedNodeSet Tmp;
getCheckerManager().runCheckersForLocation(Tmp, Src, location, isLoad, S,
*this);
BldrTop.addNodes(Tmp);
}
std::pair<const ProgramPointTag *, const ProgramPointTag*>
ExprEngine::getEagerlyAssumeTags() {
static SimpleProgramPointTag
EagerlyAssumeTrue("ExprEngine : Eagerly Assume True"),
EagerlyAssumeFalse("ExprEngine : Eagerly Assume False");
return std::make_pair(&EagerlyAssumeTrue, &EagerlyAssumeFalse);
}
void ExprEngine::evalEagerlyAssume(ExplodedNodeSet &Dst, ExplodedNodeSet &Src,
const Expr *Ex) {
StmtNodeBuilder Bldr(Src, Dst, *currentBuilderContext);
for (ExplodedNodeSet::iterator I=Src.begin(), E=Src.end(); I!=E; ++I) {
ExplodedNode *Pred = *I;
// Test if the previous node was as the same expression. This can happen
// when the expression fails to evaluate to anything meaningful and
// (as an optimization) we don't generate a node.
ProgramPoint P = Pred->getLocation();
if (!isa<PostStmt>(P) || cast<PostStmt>(P).getStmt() != Ex) {
continue;
}
ProgramStateRef state = Pred->getState();
SVal V = state->getSVal(Ex, Pred->getLocationContext());
nonloc::SymbolVal *SEV = dyn_cast<nonloc::SymbolVal>(&V);
if (SEV && SEV->isExpression()) {
const std::pair<const ProgramPointTag *, const ProgramPointTag*> &tags =
getEagerlyAssumeTags();
// First assume that the condition is true.
if (ProgramStateRef StateTrue = state->assume(*SEV, true)) {
SVal Val = svalBuilder.makeIntVal(1U, Ex->getType());
StateTrue = StateTrue->BindExpr(Ex, Pred->getLocationContext(), Val);
Bldr.generateNode(Ex, Pred, StateTrue, false, tags.first);
}
// Next, assume that the condition is false.
if (ProgramStateRef StateFalse = state->assume(*SEV, false)) {
SVal Val = svalBuilder.makeIntVal(0U, Ex->getType());
StateFalse = StateFalse->BindExpr(Ex, Pred->getLocationContext(), Val);
Bldr.generateNode(Ex, Pred, StateFalse, false, tags.second);
}
}
}
}
void ExprEngine::VisitAsmStmt(const AsmStmt *A, ExplodedNode *Pred,
ExplodedNodeSet &Dst) {
StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext);
// We have processed both the inputs and the outputs. All of the outputs
// should evaluate to Locs. Nuke all of their values.
// FIXME: Some day in the future it would be nice to allow a "plug-in"
// which interprets the inline asm and stores proper results in the
// outputs.
ProgramStateRef state = Pred->getState();
for (AsmStmt::const_outputs_iterator OI = A->begin_outputs(),
OE = A->end_outputs(); OI != OE; ++OI) {
SVal X = state->getSVal(*OI, Pred->getLocationContext());
assert (!isa<NonLoc>(X)); // Should be an Lval, or unknown, undef.
if (isa<Loc>(X))
state = state->bindLoc(cast<Loc>(X), UnknownVal());
}
Bldr.generateNode(A, Pred, state);
}
//===----------------------------------------------------------------------===//
// Visualization.
//===----------------------------------------------------------------------===//
#ifndef NDEBUG
static ExprEngine* GraphPrintCheckerState;
static SourceManager* GraphPrintSourceManager;
namespace llvm {
template<>
struct DOTGraphTraits<ExplodedNode*> :
public DefaultDOTGraphTraits {
DOTGraphTraits (bool isSimple=false) : DefaultDOTGraphTraits(isSimple) {}
// FIXME: Since we do not cache error nodes in ExprEngine now, this does not
// work.
static std::string getNodeAttributes(const ExplodedNode *N, void*) {
#if 0
// FIXME: Replace with a general scheme to tell if the node is
// an error node.
if (GraphPrintCheckerState->isImplicitNullDeref(N) ||
GraphPrintCheckerState->isExplicitNullDeref(N) ||
GraphPrintCheckerState->isUndefDeref(N) ||
GraphPrintCheckerState->isUndefStore(N) ||
GraphPrintCheckerState->isUndefControlFlow(N) ||
GraphPrintCheckerState->isUndefResult(N) ||
GraphPrintCheckerState->isBadCall(N) ||
GraphPrintCheckerState->isUndefArg(N))
return "color=\"red\",style=\"filled\"";
if (GraphPrintCheckerState->isNoReturnCall(N))
return "color=\"blue\",style=\"filled\"";
#endif
return "";
}
static std::string getNodeLabel(const ExplodedNode *N, void*){
std::string sbuf;
llvm::raw_string_ostream Out(sbuf);
// Program Location.
ProgramPoint Loc = N->getLocation();
switch (Loc.getKind()) {
case ProgramPoint::BlockEntranceKind:
Out << "Block Entrance: B"
<< cast<BlockEntrance>(Loc).getBlock()->getBlockID();
break;
case ProgramPoint::BlockExitKind:
assert (false);
break;
case ProgramPoint::CallEnterKind:
Out << "CallEnter";
break;
case ProgramPoint::CallExitKind:
Out << "CallExit";
break;
default: {
if (StmtPoint *L = dyn_cast<StmtPoint>(&Loc)) {
const Stmt *S = L->getStmt();
SourceLocation SLoc = S->getLocStart();
Out << S->getStmtClassName() << ' ' << (void*) S << ' ';
LangOptions LO; // FIXME.
S->printPretty(Out, 0, PrintingPolicy(LO));
if (SLoc.isFileID()) {
Out << "\\lline="
<< GraphPrintSourceManager->getExpansionLineNumber(SLoc)
<< " col="
<< GraphPrintSourceManager->getExpansionColumnNumber(SLoc)
<< "\\l";
}
if (isa<PreStmt>(Loc))
Out << "\\lPreStmt\\l;";
else if (isa<PostLoad>(Loc))
Out << "\\lPostLoad\\l;";
else if (isa<PostStore>(Loc))
Out << "\\lPostStore\\l";
else if (isa<PostLValue>(Loc))
Out << "\\lPostLValue\\l";
#if 0
// FIXME: Replace with a general scheme to determine
// the name of the check.
if (GraphPrintCheckerState->isImplicitNullDeref(N))
Out << "\\|Implicit-Null Dereference.\\l";
else if (GraphPrintCheckerState->isExplicitNullDeref(N))
Out << "\\|Explicit-Null Dereference.\\l";
else if (GraphPrintCheckerState->isUndefDeref(N))
Out << "\\|Dereference of undefialied value.\\l";
else if (GraphPrintCheckerState->isUndefStore(N))
Out << "\\|Store to Undefined Loc.";
else if (GraphPrintCheckerState->isUndefResult(N))
Out << "\\|Result of operation is undefined.";
else if (GraphPrintCheckerState->isNoReturnCall(N))
Out << "\\|Call to function marked \"noreturn\".";
else if (GraphPrintCheckerState->isBadCall(N))
Out << "\\|Call to NULL/Undefined.";
else if (GraphPrintCheckerState->isUndefArg(N))
Out << "\\|Argument in call is undefined";
#endif
break;
}
const BlockEdge &E = cast<BlockEdge>(Loc);
Out << "Edge: (B" << E.getSrc()->getBlockID() << ", B"
<< E.getDst()->getBlockID() << ')';
if (const Stmt *T = E.getSrc()->getTerminator()) {
SourceLocation SLoc = T->getLocStart();
Out << "\\|Terminator: ";
LangOptions LO; // FIXME.
E.getSrc()->printTerminator(Out, LO);
if (SLoc.isFileID()) {
Out << "\\lline="
<< GraphPrintSourceManager->getExpansionLineNumber(SLoc)
<< " col="
<< GraphPrintSourceManager->getExpansionColumnNumber(SLoc);
}
if (isa<SwitchStmt>(T)) {
const Stmt *Label = E.getDst()->getLabel();
if (Label) {
if (const CaseStmt *C = dyn_cast<CaseStmt>(Label)) {
Out << "\\lcase ";
LangOptions LO; // FIXME.
C->getLHS()->printPretty(Out, 0, PrintingPolicy(LO));
if (const Stmt *RHS = C->getRHS()) {
Out << " .. ";
RHS->printPretty(Out, 0, PrintingPolicy(LO));
}
Out << ":";
}
else {
assert (isa<DefaultStmt>(Label));
Out << "\\ldefault:";
}
}
else
Out << "\\l(implicit) default:";
}
else if (isa<IndirectGotoStmt>(T)) {
// FIXME
}
else {
Out << "\\lCondition: ";
if (*E.getSrc()->succ_begin() == E.getDst())
Out << "true";
else
Out << "false";
}
Out << "\\l";
}
#if 0
// FIXME: Replace with a general scheme to determine
// the name of the check.
if (GraphPrintCheckerState->isUndefControlFlow(N)) {
Out << "\\|Control-flow based on\\lUndefined value.\\l";
}
#endif
}
}
ProgramStateRef state = N->getState();
Out << "\\|StateID: " << (void*) state.getPtr()
<< " NodeID: " << (void*) N << "\\|";
state->printDOT(Out);
Out << "\\l";
if (const ProgramPointTag *tag = Loc.getTag()) {
Out << "\\|Tag: " << tag->getTagDescription();
Out << "\\l";
}
return Out.str();
}
};
} // end llvm namespace
#endif
#ifndef NDEBUG
template <typename ITERATOR>
ExplodedNode *GetGraphNode(ITERATOR I) { return *I; }
template <> ExplodedNode*
GetGraphNode<llvm::DenseMap<ExplodedNode*, Expr*>::iterator>
(llvm::DenseMap<ExplodedNode*, Expr*>::iterator I) {
return I->first;
}
#endif
void ExprEngine::ViewGraph(bool trim) {
#ifndef NDEBUG
if (trim) {
std::vector<ExplodedNode*> Src;
// Flush any outstanding reports to make sure we cover all the nodes.
// This does not cause them to get displayed.
for (BugReporter::iterator I=BR.begin(), E=BR.end(); I!=E; ++I)
const_cast<BugType*>(*I)->FlushReports(BR);
// Iterate through the reports and get their nodes.
for (BugReporter::EQClasses_iterator
EI = BR.EQClasses_begin(), EE = BR.EQClasses_end(); EI != EE; ++EI) {
BugReportEquivClass& EQ = *EI;
const BugReport &R = **EQ.begin();
ExplodedNode *N = const_cast<ExplodedNode*>(R.getErrorNode());
if (N) Src.push_back(N);
}
ViewGraph(&Src[0], &Src[0]+Src.size());
}
else {
GraphPrintCheckerState = this;
GraphPrintSourceManager = &getContext().getSourceManager();
llvm::ViewGraph(*G.roots_begin(), "ExprEngine");
GraphPrintCheckerState = NULL;
GraphPrintSourceManager = NULL;
}
#endif
}
void ExprEngine::ViewGraph(ExplodedNode** Beg, ExplodedNode** End) {
#ifndef NDEBUG
GraphPrintCheckerState = this;
GraphPrintSourceManager = &getContext().getSourceManager();
std::auto_ptr<ExplodedGraph> TrimmedG(G.Trim(Beg, End).first);
if (!TrimmedG.get())
llvm::errs() << "warning: Trimmed ExplodedGraph is empty.\n";
else
llvm::ViewGraph(*TrimmedG->roots_begin(), "TrimmedExprEngine");
GraphPrintCheckerState = NULL;
GraphPrintSourceManager = NULL;
#endif
}
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