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llvm-project/clang/lib/Checker/BugReporterVisitors.cpp

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// BugReporterVisitors.cpp - Helpers for reporting bugs -----------*- 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 set of BugReporter "visitors" which can be used to
// enhance the diagnostics reported for a bug.
//
//===----------------------------------------------------------------------===//
#include "clang/AST/Expr.h"
#include "clang/AST/ExprObjC.h"
#include "clang/Checker/BugReporter/BugReporter.h"
#include "clang/Checker/BugReporter/PathDiagnostic.h"
#include "clang/Checker/PathSensitive/ExplodedGraph.h"
#include "clang/Checker/PathSensitive/GRState.h"
using namespace clang;
//===----------------------------------------------------------------------===//
// Utility functions.
//===----------------------------------------------------------------------===//
const Stmt *clang::bugreporter::GetDerefExpr(const ExplodedNode *N) {
// Pattern match for a few useful cases (do something smarter later):
// a[0], p->f, *p
const Stmt *S = N->getLocationAs<PostStmt>()->getStmt();
if (const UnaryOperator *U = dyn_cast<UnaryOperator>(S)) {
if (U->getOpcode() == UO_Deref)
return U->getSubExpr()->IgnoreParenCasts();
}
else if (const MemberExpr *ME = dyn_cast<MemberExpr>(S)) {
return ME->getBase()->IgnoreParenCasts();
}
else if (const ArraySubscriptExpr *AE = dyn_cast<ArraySubscriptExpr>(S)) {
// Retrieve the base for arrays since BasicStoreManager doesn't know how
// to reason about them.
return AE->getBase();
}
return NULL;
}
const Stmt*
clang::bugreporter::GetDenomExpr(const ExplodedNode *N) {
const Stmt *S = N->getLocationAs<PreStmt>()->getStmt();
if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(S))
return BE->getRHS();
return NULL;
}
const Stmt*
clang::bugreporter::GetCalleeExpr(const ExplodedNode *N) {
// Callee is checked as a PreVisit to the CallExpr.
const Stmt *S = N->getLocationAs<PreStmt>()->getStmt();
if (const CallExpr *CE = dyn_cast<CallExpr>(S))
return CE->getCallee();
return NULL;
}
const Stmt*
clang::bugreporter::GetRetValExpr(const ExplodedNode *N) {
const Stmt *S = N->getLocationAs<PostStmt>()->getStmt();
if (const ReturnStmt *RS = dyn_cast<ReturnStmt>(S))
return RS->getRetValue();
return NULL;
}
//===----------------------------------------------------------------------===//
// Definitions for bug reporter visitors.
//===----------------------------------------------------------------------===//
namespace {
class FindLastStoreBRVisitor : public BugReporterVisitor {
const MemRegion *R;
SVal V;
bool satisfied;
const ExplodedNode *StoreSite;
public:
FindLastStoreBRVisitor(SVal v, const MemRegion *r)
: R(r), V(v), satisfied(false), StoreSite(0) {}
virtual void Profile(llvm::FoldingSetNodeID &ID) const {
static int tag = 0;
ID.AddPointer(&tag);
ID.AddPointer(R);
ID.Add(V);
}
PathDiagnosticPiece* VisitNode(const ExplodedNode *N,
const ExplodedNode *PrevN,
BugReporterContext& BRC) {
if (satisfied)
return NULL;
if (!StoreSite) {
const ExplodedNode *Node = N, *Last = NULL;
for ( ; Node ; Last = Node, Node = Node->getFirstPred()) {
if (const VarRegion *VR = dyn_cast<VarRegion>(R)) {
if (const PostStmt *P = Node->getLocationAs<PostStmt>())
if (const DeclStmt *DS = P->getStmtAs<DeclStmt>())
if (DS->getSingleDecl() == VR->getDecl()) {
Last = Node;
break;
}
}
if (Node->getState()->getSVal(R) != V)
break;
}
if (!Node || !Last) {
satisfied = true;
return NULL;
}
StoreSite = Last;
}
if (StoreSite != N)
return NULL;
satisfied = true;
llvm::SmallString<256> sbuf;
llvm::raw_svector_ostream os(sbuf);
if (const PostStmt *PS = N->getLocationAs<PostStmt>()) {
if (const DeclStmt *DS = PS->getStmtAs<DeclStmt>()) {
if (const VarRegion *VR = dyn_cast<VarRegion>(R)) {
os << "Variable '" << VR->getDecl() << "' ";
}
else
return NULL;
if (isa<loc::ConcreteInt>(V)) {
bool b = false;
if (R->isBoundable()) {
if (const TypedRegion *TR = dyn_cast<TypedRegion>(R)) {
if (TR->getValueType()->isObjCObjectPointerType()) {
os << "initialized to nil";
b = true;
}
}
}
if (!b)
os << "initialized to a null pointer value";
}
else if (isa<nonloc::ConcreteInt>(V)) {
os << "initialized to " << cast<nonloc::ConcreteInt>(V).getValue();
}
else if (V.isUndef()) {
if (isa<VarRegion>(R)) {
const VarDecl *VD = cast<VarDecl>(DS->getSingleDecl());
if (VD->getInit())
os << "initialized to a garbage value";
else
os << "declared without an initial value";
}
}
}
}
if (os.str().empty()) {
if (isa<loc::ConcreteInt>(V)) {
bool b = false;
if (R->isBoundable()) {
if (const TypedRegion *TR = dyn_cast<TypedRegion>(R)) {
if (TR->getValueType()->isObjCObjectPointerType()) {
os << "nil object reference stored to ";
b = true;
}
}
}
if (!b)
os << "Null pointer value stored to ";
}
else if (V.isUndef()) {
os << "Uninitialized value stored to ";
}
else if (isa<nonloc::ConcreteInt>(V)) {
os << "The value " << cast<nonloc::ConcreteInt>(V).getValue()
<< " is assigned to ";
}
else
return NULL;
if (const VarRegion *VR = dyn_cast<VarRegion>(R)) {
os << '\'' << VR->getDecl() << '\'';
}
else
return NULL;
}
// FIXME: Refactor this into BugReporterContext.
const Stmt *S = 0;
ProgramPoint P = N->getLocation();
if (BlockEdge *BE = dyn_cast<BlockEdge>(&P)) {
const CFGBlock *BSrc = BE->getSrc();
S = BSrc->getTerminatorCondition();
}
else if (PostStmt *PS = dyn_cast<PostStmt>(&P)) {
S = PS->getStmt();
}
if (!S)
return NULL;
// Construct a new PathDiagnosticPiece.
PathDiagnosticLocation L(S, BRC.getSourceManager());
return new PathDiagnosticEventPiece(L, os.str());
}
};
static void registerFindLastStore(BugReporterContext& BRC, const MemRegion *R,
SVal V) {
BRC.addVisitor(new FindLastStoreBRVisitor(V, R));
}
class TrackConstraintBRVisitor : public BugReporterVisitor {
DefinedSVal Constraint;
const bool Assumption;
bool isSatisfied;
public:
TrackConstraintBRVisitor(DefinedSVal constraint, bool assumption)
: Constraint(constraint), Assumption(assumption), isSatisfied(false) {}
void Profile(llvm::FoldingSetNodeID &ID) const {
static int tag = 0;
ID.AddPointer(&tag);
ID.AddBoolean(Assumption);
ID.Add(Constraint);
}
PathDiagnosticPiece* VisitNode(const ExplodedNode *N,
const ExplodedNode *PrevN,
BugReporterContext& BRC) {
if (isSatisfied)
return NULL;
// Check if in the previous state it was feasible for this constraint
// to *not* be true.
if (PrevN->getState()->assume(Constraint, !Assumption)) {
isSatisfied = true;
// As a sanity check, make sure that the negation of the constraint
// was infeasible in the current state. If it is feasible, we somehow
// missed the transition point.
if (N->getState()->assume(Constraint, !Assumption))
return NULL;
// We found the transition point for the constraint. We now need to
// pretty-print the constraint. (work-in-progress)
std::string sbuf;
llvm::raw_string_ostream os(sbuf);
if (isa<Loc>(Constraint)) {
os << "Assuming pointer value is ";
os << (Assumption ? "non-null" : "null");
}
if (os.str().empty())
return NULL;
// FIXME: Refactor this into BugReporterContext.
const Stmt *S = 0;
ProgramPoint P = N->getLocation();
if (BlockEdge *BE = dyn_cast<BlockEdge>(&P)) {
const CFGBlock *BSrc = BE->getSrc();
S = BSrc->getTerminatorCondition();
}
else if (PostStmt *PS = dyn_cast<PostStmt>(&P)) {
S = PS->getStmt();
}
if (!S)
return NULL;
// Construct a new PathDiagnosticPiece.
PathDiagnosticLocation L(S, BRC.getSourceManager());
return new PathDiagnosticEventPiece(L, os.str());
}
return NULL;
}
};
} // end anonymous namespace
static void registerTrackConstraint(BugReporterContext& BRC,
DefinedSVal Constraint,
bool Assumption) {
BRC.addVisitor(new TrackConstraintBRVisitor(Constraint, Assumption));
}
void clang::bugreporter::registerTrackNullOrUndefValue(BugReporterContext& BRC,
const void *data,
const ExplodedNode* N) {
const Stmt *S = static_cast<const Stmt*>(data);
if (!S)
return;
GRStateManager &StateMgr = BRC.getStateManager();
const GRState *state = N->getState();
if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(S)) {
if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
const VarRegion *R =
StateMgr.getRegionManager().getVarRegion(VD, N->getLocationContext());
// What did we load?
SVal V = state->getSVal(S);
if (isa<loc::ConcreteInt>(V) || isa<nonloc::ConcreteInt>(V)
|| V.isUndef()) {
::registerFindLastStore(BRC, R, V);
}
}
}
SVal V = state->getSValAsScalarOrLoc(S);
// Uncomment this to find cases where we aren't properly getting the
// base value that was dereferenced.
// assert(!V.isUnknownOrUndef());
// Is it a symbolic value?
if (loc::MemRegionVal *L = dyn_cast<loc::MemRegionVal>(&V)) {
const SubRegion *R = cast<SubRegion>(L->getRegion());
while (R && !isa<SymbolicRegion>(R)) {
R = dyn_cast<SubRegion>(R->getSuperRegion());
}
if (R) {
assert(isa<SymbolicRegion>(R));
registerTrackConstraint(BRC, loc::MemRegionVal(R), false);
}
}
}
void clang::bugreporter::registerFindLastStore(BugReporterContext& BRC,
const void *data,
const ExplodedNode* N) {
const MemRegion *R = static_cast<const MemRegion*>(data);
if (!R)
return;
const GRState *state = N->getState();
SVal V = state->getSVal(R);
if (V.isUnknown())
return;
BRC.addVisitor(new FindLastStoreBRVisitor(V, R));
}
namespace {
class NilReceiverVisitor : public BugReporterVisitor {
public:
NilReceiverVisitor() {}
void Profile(llvm::FoldingSetNodeID &ID) const {
static int x = 0;
ID.AddPointer(&x);
}
PathDiagnosticPiece* VisitNode(const ExplodedNode *N,
const ExplodedNode *PrevN,
BugReporterContext& BRC) {
const PostStmt *P = N->getLocationAs<PostStmt>();
if (!P)
return 0;
const ObjCMessageExpr *ME = P->getStmtAs<ObjCMessageExpr>();
if (!ME)
return 0;
const Expr *Receiver = ME->getInstanceReceiver();
if (!Receiver)
return 0;
const GRState *state = N->getState();
const SVal &V = state->getSVal(Receiver);
const DefinedOrUnknownSVal *DV = dyn_cast<DefinedOrUnknownSVal>(&V);
if (!DV)
return 0;
state = state->assume(*DV, true);
if (state)
return 0;
// The receiver was nil, and hence the method was skipped.
// Register a BugReporterVisitor to issue a message telling us how
// the receiver was null.
bugreporter::registerTrackNullOrUndefValue(BRC, Receiver, N);
// Issue a message saying that the method was skipped.
PathDiagnosticLocation L(Receiver, BRC.getSourceManager());
return new PathDiagnosticEventPiece(L, "No method actually called "
"because the receiver is nil");
}
};
} // end anonymous namespace
void clang::bugreporter::registerNilReceiverVisitor(BugReporterContext &BRC) {
BRC.addVisitor(new NilReceiverVisitor());
}
// Registers every VarDecl inside a Stmt with a last store vistor.
void clang::bugreporter::registerVarDeclsLastStore(BugReporterContext &BRC,
const void *stmt,
const ExplodedNode *N) {
const Stmt *S = static_cast<const Stmt *>(stmt);
std::deque<const Stmt *> WorkList;
WorkList.push_back(S);
while (!WorkList.empty()) {
const Stmt *Head = WorkList.front();
WorkList.pop_front();
GRStateManager &StateMgr = BRC.getStateManager();
const GRState *state = N->getState();
if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Head)) {
if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
const VarRegion *R =
StateMgr.getRegionManager().getVarRegion(VD, N->getLocationContext());
// What did we load?
SVal V = state->getSVal(S);
if (isa<loc::ConcreteInt>(V) || isa<nonloc::ConcreteInt>(V)) {
::registerFindLastStore(BRC, R, V);
}
}
}
for (Stmt::const_child_iterator I = Head->child_begin();
I != Head->child_end(); ++I)
WorkList.push_back(*I);
}
}
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