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