maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity
llvm-project/clang/lib/Analysis/GRExprEngine.cpp

2421 lines
71 KiB
C++
Raw Blame History

//=-- GRExprEngine.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.
//
//===----------------------------------------------------------------------===//
#include "clang/Analysis/PathSensitive/GRExprEngine.h"
#include "clang/Analysis/PathSensitive/BugReporter.h"
#include "clang/Basic/SourceManager.h"
#include "llvm/Support/Streams.h"
#include "llvm/ADT/ImmutableList.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/raw_ostream.h"
#ifndef NDEBUG
#include "llvm/Support/GraphWriter.h"
#include <sstream>
#endif
using namespace clang;
using llvm::dyn_cast;
using llvm::cast;
using llvm::APSInt;
//===----------------------------------------------------------------------===//
// Engine construction and deletion.
//===----------------------------------------------------------------------===//
namespace {
class VISIBILITY_HIDDEN MappedBatchAuditor : public GRSimpleAPICheck {
typedef llvm::ImmutableList<GRSimpleAPICheck*> Checks;
typedef llvm::DenseMap<void*,Checks> MapTy;
MapTy M;
Checks::Factory F;
public:
MappedBatchAuditor(llvm::BumpPtrAllocator& Alloc) : F(Alloc) {}
virtual ~MappedBatchAuditor() {
llvm::DenseSet<GRSimpleAPICheck*> AlreadyVisited;
for (MapTy::iterator MI = M.begin(), ME = M.end(); MI != ME; ++MI)
for (Checks::iterator I=MI->second.begin(), E=MI->second.end(); I!=E;++I){
GRSimpleAPICheck* check = *I;
if (AlreadyVisited.count(check))
continue;
AlreadyVisited.insert(check);
delete check;
}
}
void AddCheck(GRSimpleAPICheck* A, Stmt::StmtClass C) {
assert (A && "Check cannot be null.");
void* key = reinterpret_cast<void*>((uintptr_t) C);
MapTy::iterator I = M.find(key);
M[key] = F.Concat(A, I == M.end() ? F.GetEmptyList() : I->second);
}
virtual void EmitWarnings(BugReporter& BR) {
llvm::DenseSet<GRSimpleAPICheck*> AlreadyVisited;
for (MapTy::iterator MI = M.begin(), ME = M.end(); MI != ME; ++MI)
for (Checks::iterator I=MI->second.begin(), E=MI->second.end(); I!=E;++I){
GRSimpleAPICheck* check = *I;
if (AlreadyVisited.count(check))
continue;
check->EmitWarnings(BR);
}
}
virtual bool Audit(NodeTy* N, GRStateManager& VMgr) {
Stmt* S = cast<PostStmt>(N->getLocation()).getStmt();
void* key = reinterpret_cast<void*>((uintptr_t) S->getStmtClass());
MapTy::iterator MI = M.find(key);
if (MI == M.end())
return false;
bool isSink = false;
for (Checks::iterator I=MI->second.begin(), E=MI->second.end(); I!=E; ++I)
isSink |= (*I)->Audit(N, VMgr);
return isSink;
}
};
} // end anonymous namespace
//===----------------------------------------------------------------------===//
// Engine construction and deletion.
//===----------------------------------------------------------------------===//
static inline Selector GetNullarySelector(const char* name, ASTContext& Ctx) {
IdentifierInfo* II = &Ctx.Idents.get(name);
return Ctx.Selectors.getSelector(0, &II);
}
GRExprEngine::GRExprEngine(CFG& cfg, Decl& CD, ASTContext& Ctx,
LiveVariables& L)
: CoreEngine(cfg, CD, Ctx, *this),
G(CoreEngine.getGraph()),
Liveness(L),
Builder(NULL),
StateMgr(G.getContext(), CreateBasicStoreManager,
CreateBasicConstraintManager, G.getAllocator(), G.getCFG(), L),
SymMgr(StateMgr.getSymbolManager()),
CurrentStmt(NULL),
NSExceptionII(NULL), NSExceptionInstanceRaiseSelectors(NULL),
RaiseSel(GetNullarySelector("raise", G.getContext())) {}
GRExprEngine::~GRExprEngine() {
for (BugTypeSet::iterator I = BugTypes.begin(), E = BugTypes.end(); I!=E; ++I)
delete *I;
delete [] NSExceptionInstanceRaiseSelectors;
}
//===----------------------------------------------------------------------===//
// Utility methods.
//===----------------------------------------------------------------------===//
// SaveAndRestore - A utility class that uses RIIA to save and restore
// the value of a variable.
template<typename T>
struct VISIBILITY_HIDDEN SaveAndRestore {
SaveAndRestore(T& x) : X(x), old_value(x) {}
~SaveAndRestore() { X = old_value; }
T get() { return old_value; }
T& X;
T old_value;
};
// SaveOr - Similar to SaveAndRestore. Operates only on bools; the old
// value of a variable is saved, and during the dstor the old value is
// or'ed with the new value.
struct VISIBILITY_HIDDEN SaveOr {
SaveOr(bool& x) : X(x), old_value(x) { x = false; }
~SaveOr() { X |= old_value; }
bool& X;
bool old_value;
};
void GRExprEngine::EmitWarnings(BugReporterData& BRData) {
for (bug_type_iterator I = bug_types_begin(), E = bug_types_end(); I!=E; ++I){
GRBugReporter BR(BRData, *this);
(*I)->EmitWarnings(BR);
}
if (BatchAuditor) {
GRBugReporter BR(BRData, *this);
BatchAuditor->EmitWarnings(BR);
}
}
void GRExprEngine::setTransferFunctions(GRTransferFuncs* tf) {
StateMgr.TF = tf;
tf->RegisterChecks(*this);
tf->RegisterPrinters(getStateManager().Printers);
}
void GRExprEngine::AddCheck(GRSimpleAPICheck* A, Stmt::StmtClass C) {
if (!BatchAuditor)
BatchAuditor.reset(new MappedBatchAuditor(getGraph().getAllocator()));
((MappedBatchAuditor*) BatchAuditor.get())->AddCheck(A, C);
}
const GRState* GRExprEngine::getInitialState() {
return StateMgr.getInitialState();
}
//===----------------------------------------------------------------------===//
// Top-level transfer function logic (Dispatcher).
//===----------------------------------------------------------------------===//
void GRExprEngine::ProcessStmt(Stmt* S, StmtNodeBuilder& builder) {
Builder = &builder;
EntryNode = builder.getLastNode();
// FIXME: Consolidate.
CurrentStmt = S;
StateMgr.CurrentStmt = S;
// Set up our simple checks.
if (BatchAuditor)
Builder->setAuditor(BatchAuditor.get());
// Create the cleaned state.
CleanedState = StateMgr.RemoveDeadBindings(EntryNode->getState(), CurrentStmt,
Liveness, DeadSymbols);
// Process any special transfer function for dead symbols.
NodeSet Tmp;
if (DeadSymbols.empty())
Tmp.Add(EntryNode);
else {
SaveAndRestore<bool> OldSink(Builder->BuildSinks);
SaveOr OldHasGen(Builder->HasGeneratedNode);
SaveAndRestore<bool> OldPurgeDeadSymbols(Builder->PurgingDeadSymbols);
Builder->PurgingDeadSymbols = true;
getTF().EvalDeadSymbols(Tmp, *this, *Builder, EntryNode, S,
CleanedState, DeadSymbols);
if (!Builder->BuildSinks && !Builder->HasGeneratedNode)
Tmp.Add(EntryNode);
}
bool HasAutoGenerated = false;
for (NodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
NodeSet Dst;
// Set the cleaned state.
Builder->SetCleanedState(*I == EntryNode ? CleanedState : GetState(*I));
// Visit the statement.
Visit(S, *I, Dst);
// Do we need to auto-generate a node? We only need to do this to generate
// a node with a "cleaned" state; GRCoreEngine will actually handle
// auto-transitions for other cases.
if (Dst.size() == 1 && *Dst.begin() == EntryNode
&& !Builder->HasGeneratedNode && !HasAutoGenerated) {
HasAutoGenerated = true;
builder.generateNode(S, GetState(EntryNode), *I);
}
}
// NULL out these variables to cleanup.
CleanedState = NULL;
EntryNode = NULL;
// FIXME: Consolidate.
StateMgr.CurrentStmt = 0;
CurrentStmt = 0;
Builder = NULL;
}
void GRExprEngine::Visit(Stmt* S, NodeTy* Pred, NodeSet& Dst) {
// 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 && getCFG().isBlkExpr(S)) {
Dst.Add(Pred);
return;
}
switch (S->getStmtClass()) {
default:
// Cases we intentionally have "default" handle:
// AddrLabelExpr, IntegerLiteral, CharacterLiteral
Dst.Add(Pred); // No-op. Simply propagate the current state unchanged.
break;
case Stmt::ArraySubscriptExprClass:
VisitArraySubscriptExpr(cast<ArraySubscriptExpr>(S), Pred, Dst, false);
break;
case Stmt::AsmStmtClass:
VisitAsmStmt(cast<AsmStmt>(S), Pred, Dst);
break;
case Stmt::BinaryOperatorClass: {
BinaryOperator* B = cast<BinaryOperator>(S);
if (B->isLogicalOp()) {
VisitLogicalExpr(B, Pred, Dst);
break;
}
else if (B->getOpcode() == BinaryOperator::Comma) {
const GRState* St = GetState(Pred);
MakeNode(Dst, B, Pred, SetRVal(St, B, GetRVal(St, B->getRHS())));
break;
}
VisitBinaryOperator(cast<BinaryOperator>(S), Pred, Dst);
break;
}
case Stmt::CallExprClass: {
CallExpr* C = cast<CallExpr>(S);
VisitCall(C, Pred, C->arg_begin(), C->arg_end(), 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
ChooseExpr* C = cast<ChooseExpr>(S);
VisitGuardedExpr(C, C->getLHS(), C->getRHS(), Pred, Dst);
break;
}
case Stmt::CompoundAssignOperatorClass:
VisitBinaryOperator(cast<BinaryOperator>(S), Pred, Dst);
break;
case Stmt::ConditionalOperatorClass: { // '?' operator
ConditionalOperator* C = cast<ConditionalOperator>(S);
VisitGuardedExpr(C, C->getLHS(), C->getRHS(), Pred, Dst);
break;
}
case Stmt::DeclRefExprClass:
VisitDeclRefExpr(cast<DeclRefExpr>(S), Pred, Dst, false);
break;
case Stmt::DeclStmtClass:
VisitDeclStmt(cast<DeclStmt>(S), Pred, Dst);
break;
case Stmt::ImplicitCastExprClass:
case Stmt::ExplicitCastExprClass: {
CastExpr* C = cast<CastExpr>(S);
VisitCast(C, C->getSubExpr(), Pred, Dst);
break;
}
case Stmt::MemberExprClass: {
VisitMemberExpr(cast<MemberExpr>(S), Pred, Dst, false);
break;
}
case Stmt::ObjCMessageExprClass: {
VisitObjCMessageExpr(cast<ObjCMessageExpr>(S), Pred, Dst);
break;
}
case Stmt::ParenExprClass:
Visit(cast<ParenExpr>(S)->getSubExpr()->IgnoreParens(), Pred, Dst);
break;
case Stmt::ReturnStmtClass:
VisitReturnStmt(cast<ReturnStmt>(S), Pred, Dst);
break;
case Stmt::SizeOfAlignOfTypeExprClass:
VisitSizeOfAlignOfTypeExpr(cast<SizeOfAlignOfTypeExpr>(S), Pred, Dst);
break;
case Stmt::StmtExprClass: {
StmtExpr* SE = cast<StmtExpr>(S);
const GRState* St = GetState(Pred);
// FIXME: Not certain if we can have empty StmtExprs. If so, we should
// probably just remove these from the CFG.
assert (!SE->getSubStmt()->body_empty());
if (Expr* LastExpr = dyn_cast<Expr>(*SE->getSubStmt()->body_rbegin()))
MakeNode(Dst, SE, Pred, SetRVal(St, SE, GetRVal(St, LastExpr)));
else
Dst.Add(Pred);
break;
}
case Stmt::UnaryOperatorClass:
VisitUnaryOperator(cast<UnaryOperator>(S), Pred, Dst, false);
break;
}
}
void GRExprEngine::VisitLVal(Expr* Ex, NodeTy* Pred, NodeSet& Dst) {
Ex = Ex->IgnoreParens();
if (Ex != CurrentStmt && getCFG().isBlkExpr(Ex)) {
Dst.Add(Pred);
return;
}
switch (Ex->getStmtClass()) {
default:
Visit(Ex, Pred, Dst);
return;
case Stmt::ArraySubscriptExprClass:
VisitArraySubscriptExpr(cast<ArraySubscriptExpr>(Ex), Pred, Dst, true);
return;
case Stmt::DeclRefExprClass:
VisitDeclRefExpr(cast<DeclRefExpr>(Ex), Pred, Dst, true);
return;
case Stmt::UnaryOperatorClass:
VisitUnaryOperator(cast<UnaryOperator>(Ex), Pred, Dst, true);
return;
case Stmt::MemberExprClass:
VisitMemberExpr(cast<MemberExpr>(Ex), Pred, Dst, true);
return;
}
}
//===----------------------------------------------------------------------===//
// Block entrance. (Update counters).
//===----------------------------------------------------------------------===//
bool GRExprEngine::ProcessBlockEntrance(CFGBlock* B, const GRState*,
GRBlockCounter BC) {
return BC.getNumVisited(B->getBlockID()) < 3;
}
//===----------------------------------------------------------------------===//
// Branch processing.
//===----------------------------------------------------------------------===//
const GRState* GRExprEngine::MarkBranch(const GRState* St,
Stmt* Terminator,
bool branchTaken) {
switch (Terminator->getStmtClass()) {
default:
return St;
case Stmt::BinaryOperatorClass: { // '&&' and '||'
BinaryOperator* B = cast<BinaryOperator>(Terminator);
BinaryOperator::Opcode Op = B->getOpcode();
assert (Op == BinaryOperator::LAnd || Op == BinaryOperator::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.
Expr* Ex = (Op == BinaryOperator::LAnd && branchTaken) ||
(Op == BinaryOperator::LOr && !branchTaken)
? B->getRHS() : B->getLHS();
return SetBlkExprRVal(St, B, UndefinedVal(Ex));
}
case Stmt::ConditionalOperatorClass: { // ?:
ConditionalOperator* C = cast<ConditionalOperator>(Terminator);
// For ?, if branchTaken == true then the value is either the LHS or
// the condition itself. (GNU extension).
Expr* Ex;
if (branchTaken)
Ex = C->getLHS() ? C->getLHS() : C->getCond();
else
Ex = C->getRHS();
return SetBlkExprRVal(St, C, UndefinedVal(Ex));
}
case Stmt::ChooseExprClass: { // ?:
ChooseExpr* C = cast<ChooseExpr>(Terminator);
Expr* Ex = branchTaken ? C->getLHS() : C->getRHS();
return SetBlkExprRVal(St, C, UndefinedVal(Ex));
}
}
}
void GRExprEngine::ProcessBranch(Expr* Condition, Stmt* Term,
BranchNodeBuilder& builder) {
// Remove old bindings for subexpressions.
const GRState* PrevState =
StateMgr.RemoveSubExprBindings(builder.getState());
// Check for NULL conditions; e.g. "for(;;)"
if (!Condition) {
builder.markInfeasible(false);
return;
}
RVal V = GetRVal(PrevState, Condition);
switch (V.getBaseKind()) {
default:
break;
case RVal::UnknownKind:
builder.generateNode(MarkBranch(PrevState, Term, true), true);
builder.generateNode(MarkBranch(PrevState, Term, false), false);
return;
case RVal::UndefinedKind: {
NodeTy* N = builder.generateNode(PrevState, true);
if (N) {
N->markAsSink();
UndefBranches.insert(N);
}
builder.markInfeasible(false);
return;
}
}
// Process the true branch.
bool isFeasible = false;
const GRState* St = Assume(PrevState, V, true, isFeasible);
if (isFeasible)
builder.generateNode(MarkBranch(St, Term, true), true);
else
builder.markInfeasible(true);
// Process the false branch.
isFeasible = false;
St = Assume(PrevState, V, false, isFeasible);
if (isFeasible)
builder.generateNode(MarkBranch(St, Term, false), false);
else
builder.markInfeasible(false);
}
/// ProcessIndirectGoto - Called by GRCoreEngine. Used to generate successor
/// nodes by processing the 'effects' of a computed goto jump.
void GRExprEngine::ProcessIndirectGoto(IndirectGotoNodeBuilder& builder) {
const GRState* St = builder.getState();
RVal V = GetRVal(St, builder.getTarget());
// 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<lval::GotoLabel>(V)) {
LabelStmt* L = cast<lval::GotoLabel>(V).getLabel();
for (iterator I=builder.begin(), E=builder.end(); I != E; ++I) {
if (I.getLabel() == L) {
builder.generateNode(I, St);
return;
}
}
assert (false && "No block with label.");
return;
}
if (isa<lval::ConcreteInt>(V) || isa<UndefinedVal>(V)) {
// Dispatch to the first target and mark it as a sink.
NodeTy* N = builder.generateNode(builder.begin(), St, true);
UndefBranches.insert(N);
return;
}
// This is really a catch-all. We don't support symbolics yet.
assert (V.isUnknown());
for (iterator I=builder.begin(), E=builder.end(); I != E; ++I)
builder.generateNode(I, St);
}
void GRExprEngine::VisitGuardedExpr(Expr* Ex, Expr* L, Expr* R,
NodeTy* Pred, NodeSet& Dst) {
assert (Ex == CurrentStmt && getCFG().isBlkExpr(Ex));
const GRState* St = GetState(Pred);
RVal X = GetBlkExprRVal(St, Ex);
assert (X.isUndef());
Expr* SE = (Expr*) cast<UndefinedVal>(X).getData();
assert (SE);
X = GetBlkExprRVal(St, SE);
// Make sure that we invalidate the previous binding.
MakeNode(Dst, Ex, Pred, StateMgr.SetRVal(St, Ex, X, true, true));
}
/// ProcessSwitch - Called by GRCoreEngine. Used to generate successor
/// nodes by processing the 'effects' of a switch statement.
void GRExprEngine::ProcessSwitch(SwitchNodeBuilder& builder) {
typedef SwitchNodeBuilder::iterator iterator;
const GRState* St = builder.getState();
Expr* CondE = builder.getCondition();
RVal CondV = GetRVal(St, CondE);
if (CondV.isUndef()) {
NodeTy* N = builder.generateDefaultCaseNode(St, true);
UndefBranches.insert(N);
return;
}
const GRState* DefaultSt = St;
// While most of this can be assumed (such as the signedness), having it
// just computed makes sure everything makes the same assumptions end-to-end.
unsigned bits = getContext().getTypeSize(CondE->getType());
APSInt V1(bits, false);
APSInt V2 = V1;
bool DefaultFeasible = false;
for (iterator I = builder.begin(), EI = builder.end(); I != EI; ++I) {
CaseStmt* Case = cast<CaseStmt>(I.getCase());
// Evaluate the case.
if (!Case->getLHS()->isIntegerConstantExpr(V1, getContext(), 0, true)) {
assert (false && "Case condition must evaluate to an integer constant.");
return;
}
// Get the RHS of the case, if it exists.
if (Expr* E = Case->getRHS()) {
if (!E->isIntegerConstantExpr(V2, getContext(), 0, true)) {
assert (false &&
"Case condition (RHS) must evaluate to an integer constant.");
return ;
}
assert (V1 <= V2);
}
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 {
nonlval::ConcreteInt CaseVal(getBasicVals().getValue(V1));
RVal Res = EvalBinOp(BinaryOperator::EQ, CondV, CaseVal);
// Now "assume" that the case matches.
bool isFeasible = false;
const GRState* StNew = Assume(St, Res, true, isFeasible);
if (isFeasible) {
builder.generateCaseStmtNode(I, StNew);
// 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<nonlval::ConcreteInt>(CondV))
return;
}
// Now "assume" that the case doesn't match. Add this state
// to the default state (if it is feasible).
isFeasible = false;
StNew = Assume(DefaultSt, Res, false, isFeasible);
if (isFeasible) {
DefaultFeasible = true;
DefaultSt = StNew;
}
// Concretize the next value in the range.
if (V1 == V2)
break;
++V1;
assert (V1 <= V2);
} while (true);
}
// If we reach here, than we know that the default branch is
// possible.
if (DefaultFeasible) builder.generateDefaultCaseNode(DefaultSt);
}
//===----------------------------------------------------------------------===//
// Transfer functions: logical operations ('&&', '||').
//===----------------------------------------------------------------------===//
void GRExprEngine::VisitLogicalExpr(BinaryOperator* B, NodeTy* Pred,
NodeSet& Dst) {
assert (B->getOpcode() == BinaryOperator::LAnd ||
B->getOpcode() == BinaryOperator::LOr);
assert (B == CurrentStmt && getCFG().isBlkExpr(B));
const GRState* St = GetState(Pred);
RVal X = GetBlkExprRVal(St, B);
assert (X.isUndef());
Expr* Ex = (Expr*) cast<UndefinedVal>(X).getData();
assert (Ex);
if (Ex == B->getRHS()) {
X = GetBlkExprRVal(St, Ex);
// Handle undefined values.
if (X.isUndef()) {
MakeNode(Dst, B, Pred, SetBlkExprRVal(St, B, X));
return;
}
// We took the RHS. Because the value of the '&&' or '||' expression must
// evaluate to 0 or 1, we must assume the value of the RHS evaluates to 0
// or 1. Alternatively, we could take a lazy approach, and calculate this
// value later when necessary. We don't have the machinery in place for
// this right now, and since most logical expressions are used for branches,
// the payoff is not likely to be large. Instead, we do eager evaluation.
bool isFeasible = false;
const GRState* NewState = Assume(St, X, true, isFeasible);
if (isFeasible)
MakeNode(Dst, B, Pred,
SetBlkExprRVal(NewState, B, MakeConstantVal(1U, B)));
isFeasible = false;
NewState = Assume(St, X, false, isFeasible);
if (isFeasible)
MakeNode(Dst, B, Pred,
SetBlkExprRVal(NewState, B, MakeConstantVal(0U, B)));
}
else {
// We took the LHS expression. Depending on whether we are '&&' or
// '||' we know what the value of the expression is via properties of
// the short-circuiting.
X = MakeConstantVal( B->getOpcode() == BinaryOperator::LAnd ? 0U : 1U, B);
MakeNode(Dst, B, Pred, SetBlkExprRVal(St, B, X));
}
}
//===----------------------------------------------------------------------===//
// Transfer functions: Loads and stores.
//===----------------------------------------------------------------------===//
void GRExprEngine::VisitDeclRefExpr(DeclRefExpr* D, NodeTy* Pred, NodeSet& Dst,
bool asLVal) {
const GRState* St = GetState(Pred);
RVal X = RVal::MakeVal(getBasicVals(), D);
if (asLVal)
MakeNode(Dst, D, Pred, SetRVal(St, D, cast<LVal>(X)));
else {
RVal V = isa<lval::DeclVal>(X) ? GetRVal(St, cast<LVal>(X)) : X;
MakeNode(Dst, D, Pred, SetRVal(St, D, V));
}
}
/// VisitArraySubscriptExpr - Transfer function for array accesses
void GRExprEngine::VisitArraySubscriptExpr(ArraySubscriptExpr* A, NodeTy* Pred,
NodeSet& Dst, bool asLVal) {
Expr* Base = A->getBase()->IgnoreParens();
Expr* Idx = A->getIdx()->IgnoreParens();
// Always visit the base as an LVal expression. This computes the
// abstract address of the base object.
NodeSet Tmp;
if (LVal::IsLValType(Base->getType())) // Base always is an LVal.
Visit(Base, Pred, Tmp);
else
VisitLVal(Base, Pred, Tmp);
for (NodeSet::iterator I1=Tmp.begin(), E1=Tmp.end(); I1!=E1; ++I1) {
// Evaluate the index.
NodeSet Tmp2;
Visit(Idx, *I1, Tmp2);
for (NodeSet::iterator I2=Tmp2.begin(), E2=Tmp2.end(); I2!=E2; ++I2) {
const GRState* St = GetState(*I2);
RVal BaseV = GetRVal(St, Base);
RVal IdxV = GetRVal(St, Idx);
// If IdxV is 0, return just BaseV.
bool useBase = false;
if (nonlval::ConcreteInt* IdxInt = dyn_cast<nonlval::ConcreteInt>(&IdxV))
useBase = IdxInt->getValue() == 0;
RVal V = useBase ? BaseV : lval::ArrayOffset::Make(getBasicVals(), BaseV,IdxV);
if (asLVal)
MakeNode(Dst, A, *I2, SetRVal(St, A, V));
else
EvalLoad(Dst, A, *I2, St, V);
}
}
}
/// VisitMemberExpr - Transfer function for member expressions.
void GRExprEngine::VisitMemberExpr(MemberExpr* M, NodeTy* Pred,
NodeSet& Dst, bool asLVal) {
Expr* Base = M->getBase()->IgnoreParens();
// Always visit the base as an LVal expression. This computes the
// abstract address of the base object.
NodeSet Tmp;
if (asLVal) {
if (LVal::IsLValType(Base->getType())) // Base always is an LVal.
Visit(Base, Pred, Tmp);
else
VisitLVal(Base, Pred, Tmp);
for (NodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
const GRState* St = GetState(*I);
RVal BaseV = GetRVal(St, Base);
RVal V = lval::FieldOffset::Make(getBasicVals(), GetRVal(St, Base),
M->getMemberDecl());
MakeNode(Dst, M, *I, SetRVal(St, M, V));
}
return;
}
// Evaluate the base. Can be an LVal or NonLVal (depends on whether
// or not isArrow() is true).
Visit(Base, Pred, Tmp);
for (NodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
const GRState* St = GetState(*I);
RVal BaseV = GetRVal(St, Base);
if (LVal::IsLValType(Base->getType())) {
assert (M->isArrow());
RVal V = lval::FieldOffset::Make(getBasicVals(), GetRVal(St, Base),
M->getMemberDecl());
EvalLoad(Dst, M, *I, St, V);
}
else {
assert (!M->isArrow());
if (BaseV.isUnknownOrUndef()) {
MakeNode(Dst, M, *I, SetRVal(St, M, BaseV));
continue;
}
// FIXME: Implement nonlval objects representing struct temporaries.
assert (isa<NonLVal>(BaseV));
MakeNode(Dst, M, *I, SetRVal(St, M, UnknownVal()));
}
}
}
void GRExprEngine::EvalStore(NodeSet& Dst, Expr* Ex, NodeTy* Pred,
const GRState* St, RVal location, RVal Val) {
assert (Builder && "GRStmtNodeBuilder must be defined.");
// Evaluate the location (checks for bad dereferences).
St = EvalLocation(Ex, Pred, St, location);
if (!St)
return;
// Proceed with the store.
unsigned size = Dst.size();
SaveAndRestore<bool> OldSink(Builder->BuildSinks);
SaveAndRestore<ProgramPoint::Kind> OldSPointKind(Builder->PointKind);
SaveOr OldHasGen(Builder->HasGeneratedNode);
assert (!location.isUndef());
Builder->PointKind = ProgramPoint::PostStoreKind;
getTF().EvalStore(Dst, *this, *Builder, Ex, Pred, St, location, Val);
// Handle the case where no nodes where generated. Auto-generate that
// contains the updated state if we aren't generating sinks.
if (!Builder->BuildSinks && Dst.size() == size && !Builder->HasGeneratedNode)
getTF().GRTransferFuncs::EvalStore(Dst, *this, *Builder, Ex, Pred, St,
location, Val);
}
void GRExprEngine::EvalLoad(NodeSet& Dst, Expr* Ex, NodeTy* Pred,
const GRState* St, RVal location,
bool CheckOnly) {
// Evaluate the location (checks for bad dereferences).
St = EvalLocation(Ex, Pred, St, location, true);
if (!St)
return;
// Proceed with the load.
ProgramPoint::Kind K = ProgramPoint::PostLoadKind;
// FIXME: Currently symbolic analysis "generates" new symbols
// for the contents of values. We need a better approach.
// FIXME: The "CheckOnly" option exists only because Array and Field
// loads aren't fully implemented. Eventually this option will go away.
if (CheckOnly)
MakeNode(Dst, Ex, Pred, St, K);
else if (location.isUnknown()) {
// This is important. We must nuke the old binding.
MakeNode(Dst, Ex, Pred, SetRVal(St, Ex, UnknownVal()), K);
}
else
MakeNode(Dst, Ex, Pred, SetRVal(St, Ex, GetRVal(St, cast<LVal>(location),
Ex->getType())), K);
}
void GRExprEngine::EvalStore(NodeSet& Dst, Expr* Ex, Expr* StoreE, NodeTy* Pred,
const GRState* St, RVal location, RVal Val) {
NodeSet TmpDst;
EvalStore(TmpDst, StoreE, Pred, St, location, Val);
for (NodeSet::iterator I=TmpDst.begin(), E=TmpDst.end(); I!=E; ++I)
MakeNode(Dst, Ex, *I, (*I)->getState());
}
const GRState* GRExprEngine::EvalLocation(Expr* Ex, NodeTy* Pred,
const GRState* St,
RVal location, bool isLoad) {
// Check for loads/stores from/to undefined values.
if (location.isUndef()) {
ProgramPoint::Kind K =
isLoad ? ProgramPoint::PostLoadKind : ProgramPoint::PostStmtKind;
if (NodeTy* Succ = Builder->generateNode(Ex, St, Pred, K)) {
Succ->markAsSink();
UndefDeref.insert(Succ);
}
return NULL;
}
// Check for loads/stores from/to unknown locations. Treat as No-Ops.
if (location.isUnknown())
return St;
// During a load, one of two possible situations arise:
// (1) A crash, because the location (pointer) was NULL.
// (2) The location (pointer) is not NULL, and the dereference works.
//
// We add these assumptions.
LVal LV = cast<LVal>(location);
// "Assume" that the pointer is not NULL.
bool isFeasibleNotNull = false;
const GRState* StNotNull = Assume(St, LV, true, isFeasibleNotNull);
// "Assume" that the pointer is NULL.
bool isFeasibleNull = false;
GRStateRef StNull = GRStateRef(Assume(St, LV, false, isFeasibleNull),
getStateManager());
if (isFeasibleNull) {
// Use the Generic Data Map to mark in the state what lval was null.
const RVal* PersistentLV = getBasicVals().getPersistentRVal(LV);
StNull = StNull.set<GRState::NullDerefTag>(PersistentLV);
// We don't use "MakeNode" here because the node will be a sink
// and we have no intention of processing it later.
ProgramPoint::Kind K =
isLoad ? ProgramPoint::PostLoadKind : ProgramPoint::PostStmtKind;
NodeTy* NullNode = Builder->generateNode(Ex, StNull, Pred, K);
if (NullNode) {
NullNode->markAsSink();
if (isFeasibleNotNull) ImplicitNullDeref.insert(NullNode);
else ExplicitNullDeref.insert(NullNode);
}
}
return isFeasibleNotNull ? StNotNull : NULL;
}
//===----------------------------------------------------------------------===//
// Transfer function: Function calls.
//===----------------------------------------------------------------------===//
void GRExprEngine::VisitCall(CallExpr* CE, NodeTy* Pred,
CallExpr::arg_iterator AI,
CallExpr::arg_iterator AE,
NodeSet& Dst) {
// Process the arguments.
if (AI != AE) {
NodeSet DstTmp;
Visit(*AI, Pred, DstTmp);
++AI;
for (NodeSet::iterator DI=DstTmp.begin(), DE=DstTmp.end(); DI != DE; ++DI)
VisitCall(CE, *DI, AI, AE, Dst);
return;
}
// If we reach here we have processed all of the arguments. Evaluate
// the callee expression.
NodeSet DstTmp;
Expr* Callee = CE->getCallee()->IgnoreParens();
VisitLVal(Callee, Pred, DstTmp);
// Finally, evaluate the function call.
for (NodeSet::iterator DI = DstTmp.begin(), DE = DstTmp.end(); DI!=DE; ++DI) {
const GRState* St = GetState(*DI);
RVal L = GetRVal(St, Callee);
// FIXME: Add support for symbolic function calls (calls involving
// function pointer values that are symbolic).
// Check for undefined control-flow or calls to NULL.
if (L.isUndef() || isa<lval::ConcreteInt>(L)) {
NodeTy* N = Builder->generateNode(CE, St, *DI);
if (N) {
N->markAsSink();
BadCalls.insert(N);
}
continue;
}
// Check for the "noreturn" attribute.
SaveAndRestore<bool> OldSink(Builder->BuildSinks);
if (isa<lval::FuncVal>(L)) {
FunctionDecl* FD = cast<lval::FuncVal>(L).getDecl();
if (FD->getAttr<NoReturnAttr>())
Builder->BuildSinks = true;
else {
// HACK: Some functions are not marked noreturn, and don't return.
// Here are a few hardwired ones. If this takes too long, we can
// potentially cache these results.
const char* s = FD->getIdentifier()->getName();
unsigned n = strlen(s);
switch (n) {
default:
break;
case 4:
if (!memcmp(s, "exit", 4)) Builder->BuildSinks = true;
break;
case 5:
if (!memcmp(s, "panic", 5)) Builder->BuildSinks = true;
break;
case 6:
if (!memcmp(s, "Assert", 6)) {
Builder->BuildSinks = true;
break;
}
// FIXME: This is just a wrapper around throwing an exception.
// Eventually inter-procedural analysis should handle this easily.
if (!memcmp(s, "ziperr", 6)) Builder->BuildSinks = true;
break;
case 7:
if (!memcmp(s, "assfail", 7)) Builder->BuildSinks = true;
break;
case 8:
if (!memcmp(s ,"db_error", 8)) Builder->BuildSinks = true;
break;
case 12:
if (!memcmp(s, "__assert_rtn", 12)) Builder->BuildSinks = true;
break;
case 13:
if (!memcmp(s, "__assert_fail", 13)) Builder->BuildSinks = true;
break;
case 14:
if (!memcmp(s, "dtrace_assfail", 14)) Builder->BuildSinks = true;
break;
case 26:
if (!memcmp(s, "_XCAssertionFailureHandler", 26) ||
!memcmp(s, "_DTAssertionFailureHandler", 26))
Builder->BuildSinks = true;
break;
}
}
}
// Evaluate the call.
if (isa<lval::FuncVal>(L)) {
IdentifierInfo* Info = cast<lval::FuncVal>(L).getDecl()->getIdentifier();
if (unsigned id = Info->getBuiltinID())
switch (id) {
case Builtin::BI__builtin_expect: {
// For __builtin_expect, just return the value of the subexpression.
assert (CE->arg_begin() != CE->arg_end());
RVal X = GetRVal(St, *(CE->arg_begin()));
MakeNode(Dst, CE, *DI, SetRVal(St, CE, X));
continue;
}
default:
break;
}
}
// Check any arguments passed-by-value against being undefined.
bool badArg = false;
for (CallExpr::arg_iterator I = CE->arg_begin(), E = CE->arg_end();
I != E; ++I) {
if (GetRVal(GetState(*DI), *I).isUndef()) {
NodeTy* N = Builder->generateNode(CE, GetState(*DI), *DI);
if (N) {
N->markAsSink();
UndefArgs[N] = *I;
}
badArg = true;
break;
}
}
if (badArg)
continue;
// Dispatch to the plug-in transfer function.
unsigned size = Dst.size();
SaveOr OldHasGen(Builder->HasGeneratedNode);
EvalCall(Dst, CE, L, *DI);
// Handle the case where no nodes where generated. Auto-generate that
// contains the updated state if we aren't generating sinks.
if (!Builder->BuildSinks && Dst.size() == size &&
!Builder->HasGeneratedNode)
MakeNode(Dst, CE, *DI, St);
}
}
//===----------------------------------------------------------------------===//
// Transfer function: Objective-C message expressions.
//===----------------------------------------------------------------------===//
void GRExprEngine::VisitObjCMessageExpr(ObjCMessageExpr* ME, NodeTy* Pred,
NodeSet& Dst){
VisitObjCMessageExprArgHelper(ME, ME->arg_begin(), ME->arg_end(),
Pred, Dst);
}
void GRExprEngine::VisitObjCMessageExprArgHelper(ObjCMessageExpr* ME,
ObjCMessageExpr::arg_iterator AI,
ObjCMessageExpr::arg_iterator AE,
NodeTy* Pred, NodeSet& Dst) {
if (AI == AE) {
// Process the receiver.
if (Expr* Receiver = ME->getReceiver()) {
NodeSet Tmp;
Visit(Receiver, Pred, Tmp);
for (NodeSet::iterator NI = Tmp.begin(), NE = Tmp.end(); NI != NE; ++NI)
VisitObjCMessageExprDispatchHelper(ME, *NI, Dst);
return;
}
VisitObjCMessageExprDispatchHelper(ME, Pred, Dst);
return;
}
NodeSet Tmp;
Visit(*AI, Pred, Tmp);
++AI;
for (NodeSet::iterator NI = Tmp.begin(), NE = Tmp.end(); NI != NE; ++NI)
VisitObjCMessageExprArgHelper(ME, AI, AE, *NI, Dst);
}
void GRExprEngine::VisitObjCMessageExprDispatchHelper(ObjCMessageExpr* ME,
NodeTy* Pred,
NodeSet& Dst) {
// FIXME: More logic for the processing the method call.
const GRState* St = GetState(Pred);
bool RaisesException = false;
if (Expr* Receiver = ME->getReceiver()) {
RVal L = GetRVal(St, Receiver);
// Check for undefined control-flow or calls to NULL.
if (L.isUndef()) {
NodeTy* N = Builder->generateNode(ME, St, Pred);
if (N) {
N->markAsSink();
UndefReceivers.insert(N);
}
return;
}
// Check if the "raise" message was sent.
if (ME->getSelector() == RaiseSel)
RaisesException = true;
}
else {
IdentifierInfo* ClsName = ME->getClassName();
Selector S = ME->getSelector();
// Check for special instance methods.
if (!NSExceptionII) {
ASTContext& Ctx = getContext();
NSExceptionII = &Ctx.Idents.get("NSException");
}
if (ClsName == NSExceptionII) {
enum { NUM_RAISE_SELECTORS = 2 };
// Lazily create a cache of the selectors.
if (!NSExceptionInstanceRaiseSelectors) {
ASTContext& Ctx = getContext();
NSExceptionInstanceRaiseSelectors = new Selector[NUM_RAISE_SELECTORS];
llvm::SmallVector<IdentifierInfo*, NUM_RAISE_SELECTORS> II;
unsigned idx = 0;
// raise:format:
II.push_back(&Ctx.Idents.get("raise"));
II.push_back(&Ctx.Idents.get("format"));
NSExceptionInstanceRaiseSelectors[idx++] =
Ctx.Selectors.getSelector(II.size(), &II[0]);
// raise:format::arguments:
II.push_back(&Ctx.Idents.get("arguments"));
NSExceptionInstanceRaiseSelectors[idx++] =
Ctx.Selectors.getSelector(II.size(), &II[0]);
}
for (unsigned i = 0; i < NUM_RAISE_SELECTORS; ++i)
if (S == NSExceptionInstanceRaiseSelectors[i]) {
RaisesException = true; break;
}
}
}
// Check for any arguments that are uninitialized/undefined.
for (ObjCMessageExpr::arg_iterator I = ME->arg_begin(), E = ME->arg_end();
I != E; ++I) {
if (GetRVal(St, *I).isUndef()) {
// Generate an error node for passing an uninitialized/undefined value
// as an argument to a message expression. This node is a sink.
NodeTy* N = Builder->generateNode(ME, St, Pred);
if (N) {
N->markAsSink();
MsgExprUndefArgs[N] = *I;
}
return;
}
}
// Check if we raise an exception. For now treat these as sinks. Eventually
// we will want to handle exceptions properly.
SaveAndRestore<bool> OldSink(Builder->BuildSinks);
if (RaisesException)
Builder->BuildSinks = true;
// Dispatch to plug-in transfer function.
unsigned size = Dst.size();
SaveOr OldHasGen(Builder->HasGeneratedNode);
EvalObjCMessageExpr(Dst, ME, Pred);
// Handle the case where no nodes where generated. Auto-generate that
// contains the updated state if we aren't generating sinks.
if (!Builder->BuildSinks && Dst.size() == size && !Builder->HasGeneratedNode)
MakeNode(Dst, ME, Pred, St);
}
//===----------------------------------------------------------------------===//
// Transfer functions: Miscellaneous statements.
//===----------------------------------------------------------------------===//
void GRExprEngine::VisitCast(Expr* CastE, Expr* Ex, NodeTy* Pred, NodeSet& Dst){
NodeSet S1;
QualType T = CastE->getType();
if (T->isReferenceType())
VisitLVal(Ex, Pred, S1);
else
Visit(Ex, Pred, S1);
// Check for casting to "void".
if (T->isVoidType()) {
for (NodeSet::iterator I1 = S1.begin(), E1 = S1.end(); I1 != E1; ++I1)
Dst.Add(*I1);
return;
}
// FIXME: The rest of this should probably just go into EvalCall, and
// let the transfer function object be responsible for constructing
// nodes.
QualType ExTy = Ex->getType();
for (NodeSet::iterator I1 = S1.begin(), E1 = S1.end(); I1 != E1; ++I1) {
NodeTy* N = *I1;
const GRState* St = GetState(N);
RVal V = GetRVal(St, Ex);
// Unknown?
if (V.isUnknown()) {
Dst.Add(N);
continue;
}
// Undefined?
if (V.isUndef()) {
MakeNode(Dst, CastE, N, SetRVal(St, CastE, V));
continue;
}
// For const casts, just propagate the value.
ASTContext& C = getContext();
if (C.getCanonicalType(T).getUnqualifiedType() ==
C.getCanonicalType(ExTy).getUnqualifiedType()) {
MakeNode(Dst, CastE, N, SetRVal(St, CastE, V));
continue;
}
// Check for casts from pointers to integers.
if (T->isIntegerType() && LVal::IsLValType(ExTy)) {
unsigned bits = getContext().getTypeSize(ExTy);
// FIXME: Determine if the number of bits of the target type is
// equal or exceeds the number of bits to store the pointer value.
// If not, flag an error.
V = nonlval::LValAsInteger::Make(getBasicVals(), cast<LVal>(V), bits);
MakeNode(Dst, CastE, N, SetRVal(St, CastE, V));
continue;
}
// Check for casts from integers to pointers.
if (LVal::IsLValType(T) && ExTy->isIntegerType())
if (nonlval::LValAsInteger *LV = dyn_cast<nonlval::LValAsInteger>(&V)) {
// Just unpackage the lval and return it.
V = LV->getLVal();
MakeNode(Dst, CastE, N, SetRVal(St, CastE, V));
continue;
}
// All other cases.
MakeNode(Dst, CastE, N, SetRVal(St, CastE, EvalCast(V, CastE->getType())));
}
}
void GRExprEngine::VisitDeclStmt(DeclStmt* DS, NodeTy* Pred, NodeSet& Dst) {
// The CFG has one DeclStmt per Decl, so we don't need to walk the
// Decl chain.
ScopedDecl* D = DS->getDecl();
if (!D || !isa<VarDecl>(D))
return;
const VarDecl* VD = dyn_cast<VarDecl>(D);
// FIXME: Add support for local arrays.
if (VD->getType()->isArrayType()) {
return;
}
Expr* Ex = const_cast<Expr*>(VD->getInit());
// FIXME: static variables may have an initializer, but the second
// time a function is called those values may not be current.
NodeSet Tmp;
if (Ex)
Visit(Ex, Pred, Tmp);
if (Tmp.empty())
Tmp.Add(Pred);
for (NodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
const GRState* St = GetState(*I);
St = StateMgr.AddDecl(St, VD, Ex, Builder->getCurrentBlockCount());
MakeNode(Dst, DS, *I, St);
}
}
/// VisitSizeOfAlignOfTypeExpr - Transfer function for sizeof(type).
void GRExprEngine::VisitSizeOfAlignOfTypeExpr(SizeOfAlignOfTypeExpr* Ex,
NodeTy* Pred,
NodeSet& Dst) {
QualType T = Ex->getArgumentType();
uint64_t amt;
if (Ex->isSizeOf()) {
// FIXME: Add support for VLAs.
if (!T.getTypePtr()->isConstantSizeType())
return;
// Some code tries to take the sizeof an ObjCInterfaceType, relying that
// the compiler has laid out its representation. Just report Unknown
// for these.
if (T->isObjCInterfaceType())
return;
amt = 1; // Handle sizeof(void)
if (T != getContext().VoidTy)
amt = getContext().getTypeSize(T) / 8;
}
else // Get alignment of the type.
amt = getContext().getTypeAlign(T) / 8;
MakeNode(Dst, Ex, Pred,
SetRVal(GetState(Pred), Ex,
NonLVal::MakeVal(getBasicVals(), amt, Ex->getType())));
}
void GRExprEngine::VisitUnaryOperator(UnaryOperator* U, NodeTy* Pred,
NodeSet& Dst, bool asLVal) {
switch (U->getOpcode()) {
default:
break;
case UnaryOperator::Deref: {
Expr* Ex = U->getSubExpr()->IgnoreParens();
NodeSet Tmp;
Visit(Ex, Pred, Tmp);
for (NodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
const GRState* St = GetState(*I);
RVal location = GetRVal(St, Ex);
if (asLVal)
MakeNode(Dst, U, *I, SetRVal(St, U, location));
else
EvalLoad(Dst, U, *I, St, location);
}
return;
}
case UnaryOperator::Real: {
Expr* Ex = U->getSubExpr()->IgnoreParens();
NodeSet Tmp;
Visit(Ex, Pred, Tmp);
for (NodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
// FIXME: We don't have complex RValues yet.
if (Ex->getType()->isAnyComplexType()) {
// Just report "Unknown."
Dst.Add(*I);
continue;
}
// For all other types, UnaryOperator::Real is an identity operation.
assert (U->getType() == Ex->getType());
const GRState* St = GetState(*I);
MakeNode(Dst, U, *I, SetRVal(St, U, GetRVal(St, Ex)));
}
return;
}
case UnaryOperator::Imag: {
Expr* Ex = U->getSubExpr()->IgnoreParens();
NodeSet Tmp;
Visit(Ex, Pred, Tmp);
for (NodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
// FIXME: We don't have complex RValues yet.
if (Ex->getType()->isAnyComplexType()) {
// Just report "Unknown."
Dst.Add(*I);
continue;
}
// For all other types, UnaryOperator::Float returns 0.
assert (Ex->getType()->isIntegerType());
const GRState* St = GetState(*I);
RVal X = NonLVal::MakeVal(getBasicVals(), 0, Ex->getType());
MakeNode(Dst, U, *I, SetRVal(St, U, X));
}
return;
}
// FIXME: Just report "Unknown" for OffsetOf.
case UnaryOperator::OffsetOf:
Dst.Add(Pred);
return;
case UnaryOperator::Plus: assert (!asLVal); // FALL-THROUGH.
case UnaryOperator::Extension: {
// Unary "+" is a no-op, similar to a parentheses. We still have places
// where it may be a block-level expression, so we need to
// generate an extra node that just propagates the value of the
// subexpression.
Expr* Ex = U->getSubExpr()->IgnoreParens();
NodeSet Tmp;
Visit(Ex, Pred, Tmp);
for (NodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
const GRState* St = GetState(*I);
MakeNode(Dst, U, *I, SetRVal(St, U, GetRVal(St, Ex)));
}
return;
}
case UnaryOperator::AddrOf: {
assert (!asLVal);
Expr* Ex = U->getSubExpr()->IgnoreParens();
NodeSet Tmp;
VisitLVal(Ex, Pred, Tmp);
for (NodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
const GRState* St = GetState(*I);
RVal V = GetRVal(St, Ex);
St = SetRVal(St, U, V);
MakeNode(Dst, U, *I, St);
}
return;
}
case UnaryOperator::LNot:
case UnaryOperator::Minus:
case UnaryOperator::Not: {
assert (!asLVal);
Expr* Ex = U->getSubExpr()->IgnoreParens();
NodeSet Tmp;
Visit(Ex, Pred, Tmp);
for (NodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
const GRState* St = GetState(*I);
RVal V = GetRVal(St, Ex);
if (V.isUnknownOrUndef()) {
MakeNode(Dst, U, *I, SetRVal(St, U, V));
continue;
}
switch (U->getOpcode()) {
default:
assert(false && "Invalid Opcode.");
break;
case UnaryOperator::Not:
St = SetRVal(St, U, EvalComplement(cast<NonLVal>(V)));
break;
case UnaryOperator::Minus:
St = SetRVal(St, U, EvalMinus(U, cast<NonLVal>(V)));
break;
case UnaryOperator::LNot:
// C99 6.5.3.3: "The expression !E is equivalent to (0==E)."
//
// Note: technically we do "E == 0", but this is the same in the
// transfer functions as "0 == E".
if (isa<LVal>(V)) {
lval::ConcreteInt X(getBasicVals().getZeroWithPtrWidth());
RVal Result = EvalBinOp(BinaryOperator::EQ, cast<LVal>(V), X);
St = SetRVal(St, U, Result);
}
else {
nonlval::ConcreteInt X(getBasicVals().getValue(0, Ex->getType()));
#if 0
RVal Result = EvalBinOp(BinaryOperator::EQ, cast<NonLVal>(V), X);
St = SetRVal(St, U, Result);
#else
EvalBinOp(Dst, U, BinaryOperator::EQ, cast<NonLVal>(V), X, *I);
continue;
#endif
}
break;
}
MakeNode(Dst, U, *I, St);
}
return;
}
case UnaryOperator::SizeOf: {
QualType T = U->getSubExpr()->getType();
// FIXME: Add support for VLAs.
if (!T.getTypePtr()->isConstantSizeType())
return;
uint64_t size = getContext().getTypeSize(T) / 8;
const GRState* St = GetState(Pred);
St = SetRVal(St, U, NonLVal::MakeVal(getBasicVals(), size, U->getType()));
MakeNode(Dst, U, Pred, St);
return;
}
}
// Handle ++ and -- (both pre- and post-increment).
assert (U->isIncrementDecrementOp());
NodeSet Tmp;
Expr* Ex = U->getSubExpr()->IgnoreParens();
VisitLVal(Ex, Pred, Tmp);
for (NodeSet::iterator I = Tmp.begin(), E = Tmp.end(); I!=E; ++I) {
const GRState* St = GetState(*I);
RVal V1 = GetRVal(St, Ex);
// Perform a load.
NodeSet Tmp2;
EvalLoad(Tmp2, Ex, *I, St, V1);
for (NodeSet::iterator I2 = Tmp2.begin(), E2 = Tmp2.end(); I2!=E2; ++I2) {
St = GetState(*I2);
RVal V2 = GetRVal(St, Ex);
// Propagate unknown and undefined values.
if (V2.isUnknownOrUndef()) {
MakeNode(Dst, U, *I2, SetRVal(St, U, V2));
continue;
}
// Handle all other values.
BinaryOperator::Opcode Op = U->isIncrementOp() ? BinaryOperator::Add
: BinaryOperator::Sub;
RVal Result = EvalBinOp(Op, V2, MakeConstantVal(1U, U));
St = SetRVal(St, U, U->isPostfix() ? V2 : Result);
// Perform the store.
EvalStore(Dst, U, *I2, St, V1, Result);
}
}
}
void GRExprEngine::VisitAsmStmt(AsmStmt* A, NodeTy* Pred, NodeSet& Dst) {
VisitAsmStmtHelperOutputs(A, A->begin_outputs(), A->end_outputs(), Pred, Dst);
}
void GRExprEngine::VisitAsmStmtHelperOutputs(AsmStmt* A,
AsmStmt::outputs_iterator I,
AsmStmt::outputs_iterator E,
NodeTy* Pred, NodeSet& Dst) {
if (I == E) {
VisitAsmStmtHelperInputs(A, A->begin_inputs(), A->end_inputs(), Pred, Dst);
return;
}
NodeSet Tmp;
VisitLVal(*I, Pred, Tmp);
++I;
for (NodeSet::iterator NI = Tmp.begin(), NE = Tmp.end(); NI != NE; ++NI)
VisitAsmStmtHelperOutputs(A, I, E, *NI, Dst);
}
void GRExprEngine::VisitAsmStmtHelperInputs(AsmStmt* A,
AsmStmt::inputs_iterator I,
AsmStmt::inputs_iterator E,
NodeTy* Pred, NodeSet& Dst) {
if (I == E) {
// We have processed both the inputs and the outputs. All of the outputs
// should evaluate to LVals. 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.
const GRState* St = GetState(Pred);
for (AsmStmt::outputs_iterator OI = A->begin_outputs(),
OE = A->end_outputs(); OI != OE; ++OI) {
RVal X = GetRVal(St, *OI);
assert (!isa<NonLVal>(X)); // Should be an Lval, or unknown, undef.
if (isa<LVal>(X))
St = SetRVal(St, cast<LVal>(X), UnknownVal());
}
MakeNode(Dst, A, Pred, St);
return;
}
NodeSet Tmp;
Visit(*I, Pred, Tmp);
++I;
for (NodeSet::iterator NI = Tmp.begin(), NE = Tmp.end(); NI != NE; ++NI)
VisitAsmStmtHelperInputs(A, I, E, *NI, Dst);
}
void GRExprEngine::EvalReturn(NodeSet& Dst, ReturnStmt* S, NodeTy* Pred) {
assert (Builder && "GRStmtNodeBuilder must be defined.");
unsigned size = Dst.size();
SaveAndRestore<bool> OldSink(Builder->BuildSinks);
SaveOr OldHasGen(Builder->HasGeneratedNode);
getTF().EvalReturn(Dst, *this, *Builder, S, Pred);
// Handle the case where no nodes where generated.
if (!Builder->BuildSinks && Dst.size() == size && !Builder->HasGeneratedNode)
MakeNode(Dst, S, Pred, GetState(Pred));
}
void GRExprEngine::VisitReturnStmt(ReturnStmt* S, NodeTy* Pred, NodeSet& Dst) {
Expr* R = S->getRetValue();
if (!R) {
EvalReturn(Dst, S, Pred);
return;
}
NodeSet DstRet;
QualType T = R->getType();
if (T->isPointerLikeType()) {
// Check if any of the return values return the address of a stack variable.
NodeSet Tmp;
Visit(R, Pred, Tmp);
for (NodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
RVal X = GetRVal((*I)->getState(), R);
if (isa<lval::DeclVal>(X)) {
if (cast<lval::DeclVal>(X).getDecl()->hasLocalStorage()) {
// Create a special node representing the v
NodeTy* RetStackNode = Builder->generateNode(S, GetState(*I), *I);
if (RetStackNode) {
RetStackNode->markAsSink();
RetsStackAddr.insert(RetStackNode);
}
continue;
}
}
DstRet.Add(*I);
}
}
else
Visit(R, Pred, DstRet);
for (NodeSet::iterator I=DstRet.begin(), E=DstRet.end(); I!=E; ++I)
EvalReturn(Dst, S, *I);
}
//===----------------------------------------------------------------------===//
// Transfer functions: Binary operators.
//===----------------------------------------------------------------------===//
bool GRExprEngine::CheckDivideZero(Expr* Ex, const GRState* St,
NodeTy* Pred, RVal Denom) {
// Divide by undefined? (potentially zero)
if (Denom.isUndef()) {
NodeTy* DivUndef = Builder->generateNode(Ex, St, Pred);
if (DivUndef) {
DivUndef->markAsSink();
ExplicitBadDivides.insert(DivUndef);
}
return true;
}
// Check for divide/remainder-by-zero.
// First, "assume" that the denominator is 0 or undefined.
bool isFeasibleZero = false;
const GRState* ZeroSt = Assume(St, Denom, false, isFeasibleZero);
// Second, "assume" that the denominator cannot be 0.
bool isFeasibleNotZero = false;
St = Assume(St, Denom, true, isFeasibleNotZero);
// Create the node for the divide-by-zero (if it occurred).
if (isFeasibleZero)
if (NodeTy* DivZeroNode = Builder->generateNode(Ex, ZeroSt, Pred)) {
DivZeroNode->markAsSink();
if (isFeasibleNotZero)
ImplicitBadDivides.insert(DivZeroNode);
else
ExplicitBadDivides.insert(DivZeroNode);
}
return !isFeasibleNotZero;
}
void GRExprEngine::VisitBinaryOperator(BinaryOperator* B,
GRExprEngine::NodeTy* Pred,
GRExprEngine::NodeSet& Dst) {
NodeSet Tmp1;
Expr* LHS = B->getLHS()->IgnoreParens();
Expr* RHS = B->getRHS()->IgnoreParens();
if (B->isAssignmentOp())
VisitLVal(LHS, Pred, Tmp1);
else
Visit(LHS, Pred, Tmp1);
for (NodeSet::iterator I1=Tmp1.begin(), E1=Tmp1.end(); I1 != E1; ++I1) {
RVal LeftV = GetRVal((*I1)->getState(), LHS);
// Process the RHS.
NodeSet Tmp2;
Visit(RHS, *I1, Tmp2);
// With both the LHS and RHS evaluated, process the operation itself.
for (NodeSet::iterator I2=Tmp2.begin(), E2=Tmp2.end(); I2 != E2; ++I2) {
const GRState* St = GetState(*I2);
RVal RightV = GetRVal(St, RHS);
BinaryOperator::Opcode Op = B->getOpcode();
switch (Op) {
case BinaryOperator::Assign: {
// EXPERIMENTAL: "Conjured" symbols.
if (RightV.isUnknown()) {
unsigned Count = Builder->getCurrentBlockCount();
SymbolID Sym = SymMgr.getConjuredSymbol(B->getRHS(), Count);
RightV = LVal::IsLValType(B->getRHS()->getType())
? cast<RVal>(lval::SymbolVal(Sym))
: cast<RVal>(nonlval::SymbolVal(Sym));
}
// Simulate the effects of a "store": bind the value of the RHS
// to the L-Value represented by the LHS.
EvalStore(Dst, B, LHS, *I2, SetRVal(St, B, RightV), LeftV, RightV);
continue;
}
case BinaryOperator::Div:
case BinaryOperator::Rem:
// Special checking for integer denominators.
if (RHS->getType()->isIntegerType()
&& CheckDivideZero(B, St, *I2, RightV))
continue;
// FALL-THROUGH.
default: {
if (B->isAssignmentOp())
break;
// Process non-assignements except commas or short-circuited
// logical expressions (LAnd and LOr).
RVal Result = EvalBinOp(Op, LeftV, RightV);
if (Result.isUnknown()) {
Dst.Add(*I2);
continue;
}
if (Result.isUndef() && !LeftV.isUndef() && !RightV.isUndef()) {
// The operands were *not* undefined, but the result is undefined.
// This is a special node that should be flagged as an error.
if (NodeTy* UndefNode = Builder->generateNode(B, St, *I2)) {
UndefNode->markAsSink();
UndefResults.insert(UndefNode);
}
continue;
}
// Otherwise, create a new node.
MakeNode(Dst, B, *I2, SetRVal(St, B, Result));
continue;
}
}
assert (B->isCompoundAssignmentOp());
if (Op >= BinaryOperator::AndAssign)
((int&) Op) -= (BinaryOperator::AndAssign - BinaryOperator::And);
else
((int&) Op) -= BinaryOperator::MulAssign;
// Perform a load (the LHS). This performs the checks for
// null dereferences, and so on.
NodeSet Tmp3;
RVal location = GetRVal(St, LHS);
EvalLoad(Tmp3, LHS, *I2, St, location);
for (NodeSet::iterator I3=Tmp3.begin(), E3=Tmp3.end(); I3!=E3; ++I3) {
St = GetState(*I3);
RVal V = GetRVal(St, LHS);
// Propagate undefined values (left-side).
if (V.isUndef()) {
EvalStore(Dst, B, LHS, *I3, SetRVal(St, B, V), location, V);
continue;
}
// Propagate unknown values (left and right-side).
if (RightV.isUnknown() || V.isUnknown()) {
EvalStore(Dst, B, LHS, *I3, SetRVal(St, B, UnknownVal()), location,
UnknownVal());
continue;
}
// At this point:
//
// The LHS is not Undef/Unknown.
// The RHS is not Unknown.
// Get the computation type.
QualType CTy = cast<CompoundAssignOperator>(B)->getComputationType();
// Perform promotions.
V = EvalCast(V, CTy);
RightV = EvalCast(RightV, CTy);
// Evaluate operands and promote to result type.
if ((Op == BinaryOperator::Div || Op == BinaryOperator::Rem)
&& RHS->getType()->isIntegerType()) {
if (CheckDivideZero(B, St, *I3, RightV))
continue;
}
else if (RightV.isUndef()) {
// Propagate undefined values (right-side).
EvalStore(Dst, B, LHS, *I3, SetRVal(St, B, RightV), location, RightV);
continue;
}
// Compute the result of the operation.
RVal Result = EvalCast(EvalBinOp(Op, V, RightV), B->getType());
if (Result.isUndef()) {
// The operands were not undefined, but the result is undefined.
if (NodeTy* UndefNode = Builder->generateNode(B, St, *I3)) {
UndefNode->markAsSink();
UndefResults.insert(UndefNode);
}
continue;
}
EvalStore(Dst, B, LHS, *I3, SetRVal(St, B, Result), location, Result);
}
}
}
}
//===----------------------------------------------------------------------===//
// Transfer-function Helpers.
//===----------------------------------------------------------------------===//
void GRExprEngine::EvalBinOp(ExplodedNodeSet<GRState>& Dst, Expr* Ex,
BinaryOperator::Opcode Op,
NonLVal L, NonLVal R,
ExplodedNode<GRState>* Pred) {
GRStateSet OStates;
EvalBinOp(OStates, GetState(Pred), Ex, Op, L, R);
for (GRStateSet::iterator I=OStates.begin(), E=OStates.end(); I!=E; ++I)
MakeNode(Dst, Ex, Pred, *I);
}
void GRExprEngine::EvalBinOp(GRStateSet& OStates, const GRState* St,
Expr* Ex, BinaryOperator::Opcode Op,
NonLVal L, NonLVal R) {
GRStateSet::AutoPopulate AP(OStates, St);
if (R.isValid()) getTF().EvalBinOpNN(OStates, StateMgr, St, Ex, Op, L, R);
}
//===----------------------------------------------------------------------===//
// Visualization.
//===----------------------------------------------------------------------===//
#ifndef NDEBUG
static GRExprEngine* GraphPrintCheckerState;
static SourceManager* GraphPrintSourceManager;
namespace llvm {
template<>
struct VISIBILITY_HIDDEN DOTGraphTraits<GRExprEngine::NodeTy*> :
public DefaultDOTGraphTraits {
static std::string getNodeAttributes(const GRExprEngine::NodeTy* N, void*) {
if (GraphPrintCheckerState->isImplicitNullDeref(N) ||
GraphPrintCheckerState->isExplicitNullDeref(N) ||
GraphPrintCheckerState->isUndefDeref(N) ||
GraphPrintCheckerState->isUndefStore(N) ||
GraphPrintCheckerState->isUndefControlFlow(N) ||
GraphPrintCheckerState->isExplicitBadDivide(N) ||
GraphPrintCheckerState->isImplicitBadDivide(N) ||
GraphPrintCheckerState->isUndefResult(N) ||
GraphPrintCheckerState->isBadCall(N) ||
GraphPrintCheckerState->isUndefArg(N))
return "color=\"red\",style=\"filled\"";
if (GraphPrintCheckerState->isNoReturnCall(N))
return "color=\"blue\",style=\"filled\"";
return "";
}
static std::string getNodeLabel(const GRExprEngine::NodeTy* N, void*) {
std::ostringstream Out;
// 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::PostLoadKind:
case ProgramPoint::PostPurgeDeadSymbolsKind:
case ProgramPoint::PostStmtKind: {
const PostStmt& L = cast<PostStmt>(Loc);
Stmt* S = L.getStmt();
SourceLocation SLoc = S->getLocStart();
Out << S->getStmtClassName() << ' ' << (void*) S << ' ';
llvm::raw_os_ostream OutS(Out);
S->printPretty(OutS);
OutS.flush();
if (SLoc.isFileID()) {
Out << "\\lline="
<< GraphPrintSourceManager->getLineNumber(SLoc) << " col="
<< GraphPrintSourceManager->getColumnNumber(SLoc) << "\\l";
}
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 LVal.";
else if (GraphPrintCheckerState->isExplicitBadDivide(N))
Out << "\\|Explicit divide-by zero or undefined value.";
else if (GraphPrintCheckerState->isImplicitBadDivide(N))
Out << "\\|Implicit divide-by zero or undefined value.";
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";
break;
}
default: {
const BlockEdge& E = cast<BlockEdge>(Loc);
Out << "Edge: (B" << E.getSrc()->getBlockID() << ", B"
<< E.getDst()->getBlockID() << ')';
if (Stmt* T = E.getSrc()->getTerminator()) {
SourceLocation SLoc = T->getLocStart();
Out << "\\|Terminator: ";
llvm::raw_os_ostream OutS(Out);
E.getSrc()->printTerminator(OutS);
OutS.flush();
if (SLoc.isFileID()) {
Out << "\\lline="
<< GraphPrintSourceManager->getLineNumber(SLoc) << " col="
<< GraphPrintSourceManager->getColumnNumber(SLoc);
}
if (isa<SwitchStmt>(T)) {
Stmt* Label = E.getDst()->getLabel();
if (Label) {
if (CaseStmt* C = dyn_cast<CaseStmt>(Label)) {
Out << "\\lcase ";
llvm::raw_os_ostream OutS(Out);
C->getLHS()->printPretty(OutS);
OutS.flush();
if (Stmt* RHS = C->getRHS()) {
Out << " .. ";
RHS->printPretty(OutS);
OutS.flush();
}
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 (GraphPrintCheckerState->isUndefControlFlow(N)) {
Out << "\\|Control-flow based on\\lUndefined value.\\l";
}
}
}
Out << "\\|StateID: " << (void*) N->getState() << "\\|";
GRStateRef state(N->getState(), GraphPrintCheckerState->getStateManager());
state.printDOT(Out);
Out << "\\l";
return Out.str();
}
};
} // end llvm namespace
#endif
#ifndef NDEBUG
template <typename ITERATOR>
GRExprEngine::NodeTy* GetGraphNode(ITERATOR I) { return *I; }
template <>
GRExprEngine::NodeTy*
GetGraphNode<llvm::DenseMap<GRExprEngine::NodeTy*, Expr*>::iterator>
(llvm::DenseMap<GRExprEngine::NodeTy*, Expr*>::iterator I) {
return I->first;
}
template <typename ITERATOR>
static void AddSources(std::vector<GRExprEngine::NodeTy*>& Sources,
ITERATOR I, ITERATOR E) {
llvm::SmallSet<ProgramPoint,10> CachedSources;
for ( ; I != E; ++I ) {
GRExprEngine::NodeTy* N = GetGraphNode(I);
ProgramPoint P = N->getLocation();
if (CachedSources.count(P))
continue;
CachedSources.insert(P);
Sources.push_back(N);
}
}
#endif
void GRExprEngine::ViewGraph(bool trim) {
#ifndef NDEBUG
if (trim) {
std::vector<NodeTy*> Src;
// Fixme: Migrate over to the new way of adding nodes.
AddSources(Src, null_derefs_begin(), null_derefs_end());
AddSources(Src, undef_derefs_begin(), undef_derefs_end());
AddSources(Src, explicit_bad_divides_begin(), explicit_bad_divides_end());
AddSources(Src, undef_results_begin(), undef_results_end());
AddSources(Src, bad_calls_begin(), bad_calls_end());
AddSources(Src, undef_arg_begin(), undef_arg_end());
AddSources(Src, undef_branches_begin(), undef_branches_end());
// The new way.
for (BugTypeSet::iterator I=BugTypes.begin(), E=BugTypes.end(); I!=E; ++I)
(*I)->GetErrorNodes(Src);
ViewGraph(&Src[0], &Src[0]+Src.size());
}
else {
GraphPrintCheckerState = this;
GraphPrintSourceManager = &getContext().getSourceManager();
llvm::ViewGraph(*G.roots_begin(), "GRExprEngine");
GraphPrintCheckerState = NULL;
GraphPrintSourceManager = NULL;
}
#endif
}
void GRExprEngine::ViewGraph(NodeTy** Beg, NodeTy** End) {
#ifndef NDEBUG
GraphPrintCheckerState = this;
GraphPrintSourceManager = &getContext().getSourceManager();
GRExprEngine::GraphTy* TrimmedG = G.Trim(Beg, End);
if (!TrimmedG)
llvm::cerr << "warning: Trimmed ExplodedGraph is empty.\n";
else {
llvm::ViewGraph(*TrimmedG->roots_begin(), "TrimmedGRExprEngine");
delete TrimmedG;
}
GraphPrintCheckerState = NULL;
GraphPrintSourceManager = NULL;
#endif
}
Reference in New Issue View Git Blame Copy Permalink