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

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//===- SymbolManager.h - Management of Symbolic Values --------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines SymbolManager, a class that manages symbolic values
// created for use by ExprEngine and related classes.
//
//===----------------------------------------------------------------------===//
#include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Expr.h"
#include "clang/Analysis/Analyses/LiveVariables.h"
#include "clang/Analysis/AnalysisDeclContext.h"
#include "clang/Basic/LLVM.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/Store.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SymExpr.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
using namespace clang;
using namespace ento;
void SymExpr::anchor() {}
LLVM_DUMP_METHOD void SymExpr::dump() const {
dumpToStream(llvm::errs());
}
void SymIntExpr::dumpToStream(raw_ostream &os) const {
os << '(';
getLHS()->dumpToStream(os);
os << ") "
<< BinaryOperator::getOpcodeStr(getOpcode()) << ' ';
if (getRHS().isUnsigned())
os << getRHS().getZExtValue();
else
os << getRHS().getSExtValue();
if (getRHS().isUnsigned())
os << 'U';
}
void IntSymExpr::dumpToStream(raw_ostream &os) const {
if (getLHS().isUnsigned())
os << getLHS().getZExtValue();
else
os << getLHS().getSExtValue();
if (getLHS().isUnsigned())
os << 'U';
os << ' '
<< BinaryOperator::getOpcodeStr(getOpcode())
<< " (";
getRHS()->dumpToStream(os);
os << ')';
}
void SymSymExpr::dumpToStream(raw_ostream &os) const {
os << '(';
getLHS()->dumpToStream(os);
os << ") "
<< BinaryOperator::getOpcodeStr(getOpcode())
<< " (";
getRHS()->dumpToStream(os);
os << ')';
}
void SymbolCast::dumpToStream(raw_ostream &os) const {
os << '(' << ToTy.getAsString() << ") (";
Operand->dumpToStream(os);
os << ')';
}
void SymbolConjured::dumpToStream(raw_ostream &os) const {
os << "conj_$" << getSymbolID() << '{' << T.getAsString() << ", LC"
<< LCtx->getID();
if (S)
os << ", S" << S->getID(LCtx->getDecl()->getASTContext());
else
os << ", no stmt";
os << ", #" << Count << '}';
}
void SymbolDerived::dumpToStream(raw_ostream &os) const {
os << "derived_$" << getSymbolID() << '{'
<< getParentSymbol() << ',' << getRegion() << '}';
}
void SymbolExtent::dumpToStream(raw_ostream &os) const {
os << "extent_$" << getSymbolID() << '{' << getRegion() << '}';
}
void SymbolMetadata::dumpToStream(raw_ostream &os) const {
os << "meta_$" << getSymbolID() << '{'
<< getRegion() << ',' << T.getAsString() << '}';
}
void SymbolData::anchor() {}
void SymbolRegionValue::dumpToStream(raw_ostream &os) const {
os << "reg_$" << getSymbolID()
<< '<' << getType().getAsString() << ' ' << R << '>';
}
bool SymExpr::symbol_iterator::operator==(const symbol_iterator &X) const {
return itr == X.itr;
}
bool SymExpr::symbol_iterator::operator!=(const symbol_iterator &X) const {
return itr != X.itr;
}
SymExpr::symbol_iterator::symbol_iterator(const SymExpr *SE) {
itr.push_back(SE);
}
SymExpr::symbol_iterator &SymExpr::symbol_iterator::operator++() {
assert(!itr.empty() && "attempting to iterate on an 'end' iterator");
expand();
return *this;
}
SymbolRef SymExpr::symbol_iterator::operator*() {
assert(!itr.empty() && "attempting to dereference an 'end' iterator");
return itr.back();
}
void SymExpr::symbol_iterator::expand() {
const SymExpr *SE = itr.pop_back_val();
switch (SE->getKind()) {
case SymExpr::SymbolRegionValueKind:
case SymExpr::SymbolConjuredKind:
case SymExpr::SymbolDerivedKind:
case SymExpr::SymbolExtentKind:
case SymExpr::SymbolMetadataKind:
return;
case SymExpr::SymbolCastKind:
itr.push_back(cast<SymbolCast>(SE)->getOperand());
return;
case SymExpr::SymIntExprKind:
itr.push_back(cast<SymIntExpr>(SE)->getLHS());
return;
case SymExpr::IntSymExprKind:
itr.push_back(cast<IntSymExpr>(SE)->getRHS());
return;
case SymExpr::SymSymExprKind: {
const auto *x = cast<SymSymExpr>(SE);
itr.push_back(x->getLHS());
itr.push_back(x->getRHS());
return;
}
}
llvm_unreachable("unhandled expansion case");
}
const SymbolRegionValue*
SymbolManager::getRegionValueSymbol(const TypedValueRegion* R) {
llvm::FoldingSetNodeID profile;
SymbolRegionValue::Profile(profile, R);
void *InsertPos;
SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
if (!SD) {
SD = (SymExpr*) BPAlloc.Allocate<SymbolRegionValue>();
new (SD) SymbolRegionValue(SymbolCounter, R);
DataSet.InsertNode(SD, InsertPos);
++SymbolCounter;
}
return cast<SymbolRegionValue>(SD);
}
const SymbolConjured* SymbolManager::conjureSymbol(const Stmt *E,
const LocationContext *LCtx,
QualType T,
unsigned Count,
const void *SymbolTag) {
llvm::FoldingSetNodeID profile;
SymbolConjured::Profile(profile, E, T, Count, LCtx, SymbolTag);
void *InsertPos;
SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
if (!SD) {
SD = (SymExpr*) BPAlloc.Allocate<SymbolConjured>();
new (SD) SymbolConjured(SymbolCounter, E, LCtx, T, Count, SymbolTag);
DataSet.InsertNode(SD, InsertPos);
++SymbolCounter;
}
return cast<SymbolConjured>(SD);
}
const SymbolDerived*
SymbolManager::getDerivedSymbol(SymbolRef parentSymbol,
const TypedValueRegion *R) {
llvm::FoldingSetNodeID profile;
SymbolDerived::Profile(profile, parentSymbol, R);
void *InsertPos;
SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
if (!SD) {
SD = (SymExpr*) BPAlloc.Allocate<SymbolDerived>();
new (SD) SymbolDerived(SymbolCounter, parentSymbol, R);
DataSet.InsertNode(SD, InsertPos);
++SymbolCounter;
}
return cast<SymbolDerived>(SD);
}
const SymbolExtent*
SymbolManager::getExtentSymbol(const SubRegion *R) {
llvm::FoldingSetNodeID profile;
SymbolExtent::Profile(profile, R);
void *InsertPos;
SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
if (!SD) {
SD = (SymExpr*) BPAlloc.Allocate<SymbolExtent>();
new (SD) SymbolExtent(SymbolCounter, R);
DataSet.InsertNode(SD, InsertPos);
++SymbolCounter;
}
return cast<SymbolExtent>(SD);
}
const SymbolMetadata *
SymbolManager::getMetadataSymbol(const MemRegion* R, const Stmt *S, QualType T,
const LocationContext *LCtx,
unsigned Count, const void *SymbolTag) {
llvm::FoldingSetNodeID profile;
SymbolMetadata::Profile(profile, R, S, T, LCtx, Count, SymbolTag);
void *InsertPos;
SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
if (!SD) {
SD = (SymExpr*) BPAlloc.Allocate<SymbolMetadata>();
new (SD) SymbolMetadata(SymbolCounter, R, S, T, LCtx, Count, SymbolTag);
DataSet.InsertNode(SD, InsertPos);
++SymbolCounter;
}
return cast<SymbolMetadata>(SD);
}
const SymbolCast*
SymbolManager::getCastSymbol(const SymExpr *Op,
QualType From, QualType To) {
llvm::FoldingSetNodeID ID;
SymbolCast::Profile(ID, Op, From, To);
void *InsertPos;
SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
if (!data) {
data = (SymbolCast*) BPAlloc.Allocate<SymbolCast>();
new (data) SymbolCast(Op, From, To);
DataSet.InsertNode(data, InsertPos);
}
return cast<SymbolCast>(data);
}
const SymIntExpr *SymbolManager::getSymIntExpr(const SymExpr *lhs,
BinaryOperator::Opcode op,
const llvm::APSInt& v,
QualType t) {
llvm::FoldingSetNodeID ID;
SymIntExpr::Profile(ID, lhs, op, v, t);
void *InsertPos;
SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
if (!data) {
data = (SymIntExpr*) BPAlloc.Allocate<SymIntExpr>();
new (data) SymIntExpr(lhs, op, v, t);
DataSet.InsertNode(data, InsertPos);
}
return cast<SymIntExpr>(data);
}
const IntSymExpr *SymbolManager::getIntSymExpr(const llvm::APSInt& lhs,
BinaryOperator::Opcode op,
const SymExpr *rhs,
QualType t) {
llvm::FoldingSetNodeID ID;
IntSymExpr::Profile(ID, lhs, op, rhs, t);
void *InsertPos;
SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
if (!data) {
data = (IntSymExpr*) BPAlloc.Allocate<IntSymExpr>();
new (data) IntSymExpr(lhs, op, rhs, t);
DataSet.InsertNode(data, InsertPos);
}
return cast<IntSymExpr>(data);
}
const SymSymExpr *SymbolManager::getSymSymExpr(const SymExpr *lhs,
BinaryOperator::Opcode op,
const SymExpr *rhs,
QualType t) {
llvm::FoldingSetNodeID ID;
SymSymExpr::Profile(ID, lhs, op, rhs, t);
void *InsertPos;
SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
if (!data) {
data = (SymSymExpr*) BPAlloc.Allocate<SymSymExpr>();
new (data) SymSymExpr(lhs, op, rhs, t);
DataSet.InsertNode(data, InsertPos);
}
return cast<SymSymExpr>(data);
}
QualType SymbolConjured::getType() const {
return T;
}
QualType SymbolDerived::getType() const {
return R->getValueType();
}
QualType SymbolExtent::getType() const {
ASTContext &Ctx = R->getMemRegionManager().getContext();
return Ctx.getSizeType();
}
QualType SymbolMetadata::getType() const {
return T;
}
QualType SymbolRegionValue::getType() const {
return R->getValueType();
}
SymbolManager::~SymbolManager() {
llvm::DeleteContainerSeconds(SymbolDependencies);
}
bool SymbolManager::canSymbolicate(QualType T) {
T = T.getCanonicalType();
if (Loc::isLocType(T))
return true;
if (T->isIntegralOrEnumerationType())
return true;
if (T->isRecordType() && !T->isUnionType())
return true;
return false;
}
void SymbolManager::addSymbolDependency(const SymbolRef Primary,
const SymbolRef Dependent) {
SymbolDependTy::iterator I = SymbolDependencies.find(Primary);
SymbolRefSmallVectorTy *dependencies = nullptr;
if (I == SymbolDependencies.end()) {
dependencies = new SymbolRefSmallVectorTy();
SymbolDependencies[Primary] = dependencies;
} else {
dependencies = I->second;
}
dependencies->push_back(Dependent);
}
const SymbolRefSmallVectorTy *SymbolManager::getDependentSymbols(
const SymbolRef Primary) {
SymbolDependTy::const_iterator I = SymbolDependencies.find(Primary);
if (I == SymbolDependencies.end())
return nullptr;
return I->second;
}
void SymbolReaper::markDependentsLive(SymbolRef sym) {
// Do not mark dependents more then once.
SymbolMapTy::iterator LI = TheLiving.find(sym);
assert(LI != TheLiving.end() && "The primary symbol is not live.");
if (LI->second == HaveMarkedDependents)
return;
LI->second = HaveMarkedDependents;
if (const SymbolRefSmallVectorTy *Deps = SymMgr.getDependentSymbols(sym)) {
for (const auto I : *Deps) {
if (TheLiving.find(I) != TheLiving.end())
continue;
markLive(I);
}
}
}
void SymbolReaper::markLive(SymbolRef sym) {
TheLiving[sym] = NotProcessed;
markDependentsLive(sym);
}
void SymbolReaper::markLive(const MemRegion *region) {
RegionRoots.insert(region->getBaseRegion());
markElementIndicesLive(region);
}
void SymbolReaper::markElementIndicesLive(const MemRegion *region) {
for (auto SR = dyn_cast<SubRegion>(region); SR;
SR = dyn_cast<SubRegion>(SR->getSuperRegion())) {
if (const auto ER = dyn_cast<ElementRegion>(SR)) {
SVal Idx = ER->getIndex();
for (auto SI = Idx.symbol_begin(), SE = Idx.symbol_end(); SI != SE; ++SI)
markLive(*SI);
}
}
}
void SymbolReaper::markInUse(SymbolRef sym) {
if (isa<SymbolMetadata>(sym))
MetadataInUse.insert(sym);
}
bool SymbolReaper::isLiveRegion(const MemRegion *MR) {
// TODO: For now, liveness of a memory region is equivalent to liveness of its
// base region. In fact we can do a bit better: say, if a particular FieldDecl
// is not used later in the path, we can diagnose a leak of a value within
// that field earlier than, say, the variable that contains the field dies.
MR = MR->getBaseRegion();
if (RegionRoots.count(MR))
return true;
if (const auto *SR = dyn_cast<SymbolicRegion>(MR))
return isLive(SR->getSymbol());
if (const auto *VR = dyn_cast<VarRegion>(MR))
return isLive(VR, true);
// FIXME: This is a gross over-approximation. What we really need is a way to
// tell if anything still refers to this region. Unlike SymbolicRegions,
// AllocaRegions don't have associated symbols, though, so we don't actually
// have a way to track their liveness.
if (isa<AllocaRegion>(MR))
return true;
if (isa<CXXThisRegion>(MR))
return true;
if (isa<MemSpaceRegion>(MR))
return true;
if (isa<CodeTextRegion>(MR))
return true;
return false;
}
bool SymbolReaper::isLive(SymbolRef sym) {
if (TheLiving.count(sym)) {
markDependentsLive(sym);
return true;
}
bool KnownLive;
switch (sym->getKind()) {
case SymExpr::SymbolRegionValueKind:
KnownLive = isLiveRegion(cast<SymbolRegionValue>(sym)->getRegion());
break;
case SymExpr::SymbolConjuredKind:
KnownLive = false;
break;
case SymExpr::SymbolDerivedKind:
KnownLive = isLive(cast<SymbolDerived>(sym)->getParentSymbol());
break;
case SymExpr::SymbolExtentKind:
KnownLive = isLiveRegion(cast<SymbolExtent>(sym)->getRegion());
break;
case SymExpr::SymbolMetadataKind:
KnownLive = MetadataInUse.count(sym) &&
isLiveRegion(cast<SymbolMetadata>(sym)->getRegion());
if (KnownLive)
MetadataInUse.erase(sym);
break;
case SymExpr::SymIntExprKind:
KnownLive = isLive(cast<SymIntExpr>(sym)->getLHS());
break;
case SymExpr::IntSymExprKind:
KnownLive = isLive(cast<IntSymExpr>(sym)->getRHS());
break;
case SymExpr::SymSymExprKind:
KnownLive = isLive(cast<SymSymExpr>(sym)->getLHS()) &&
isLive(cast<SymSymExpr>(sym)->getRHS());
break;
case SymExpr::SymbolCastKind:
KnownLive = isLive(cast<SymbolCast>(sym)->getOperand());
break;
}
if (KnownLive)
markLive(sym);
return KnownLive;
}
bool
SymbolReaper::isLive(const Stmt *ExprVal, const LocationContext *ELCtx) const {
if (LCtx == nullptr)
return false;
if (LCtx != ELCtx) {
// If the reaper's location context is a parent of the expression's
// location context, then the expression value is now "out of scope".
if (LCtx->isParentOf(ELCtx))
return false;
return true;
}
// If no statement is provided, everything is this and parent contexts is live.
if (!Loc)
return true;
return LCtx->getAnalysis<RelaxedLiveVariables>()->isLive(Loc, ExprVal);
}
bool SymbolReaper::isLive(const VarRegion *VR, bool includeStoreBindings) const{
const StackFrameContext *VarContext = VR->getStackFrame();
if (!VarContext)
return true;
if (!LCtx)
return false;
const StackFrameContext *CurrentContext = LCtx->getStackFrame();
if (VarContext == CurrentContext) {
// If no statement is provided, everything is live.
if (!Loc)
return true;
// Anonymous parameters of an inheriting constructor are live for the entire
// duration of the constructor.
if (isa<CXXInheritedCtorInitExpr>(Loc))
return true;
if (LCtx->getAnalysis<RelaxedLiveVariables>()->isLive(Loc, VR->getDecl()))
return true;
if (!includeStoreBindings)
return false;
unsigned &cachedQuery =
const_cast<SymbolReaper *>(this)->includedRegionCache[VR];
if (cachedQuery) {
return cachedQuery == 1;
}
// Query the store to see if the region occurs in any live bindings.
if (Store store = reapedStore.getStore()) {
bool hasRegion =
reapedStore.getStoreManager().includedInBindings(store, VR);
cachedQuery = hasRegion ? 1 : 2;
return hasRegion;
}
return false;
}
return VarContext->isParentOf(CurrentContext);
}
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