541 lines
18 KiB
C++
541 lines
18 KiB
C++
//== BasicConstraintManager.cpp - Manage basic constraints.------*- C++ -*--==//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines BasicConstraintManager, a class that tracks simple
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// equality and inequality constraints on symbolic values of GRState.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/Analysis/PathSensitive/ConstraintManager.h"
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#include "clang/Analysis/PathSensitive/GRState.h"
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#include "clang/Analysis/PathSensitive/GRStateTrait.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace clang;
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namespace {
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typedef llvm::ImmutableMap<SymbolID,GRState::IntSetTy> ConstNotEqTy;
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typedef llvm::ImmutableMap<SymbolID,const llvm::APSInt*> ConstEqTy;
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// BasicConstraintManager only tracks equality and inequality constraints of
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// constants and integer variables.
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class VISIBILITY_HIDDEN BasicConstraintManager : public ConstraintManager {
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GRStateManager& StateMgr;
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GRState::IntSetTy::Factory ISetFactory;
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public:
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BasicConstraintManager(GRStateManager& statemgr)
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: StateMgr(statemgr), ISetFactory(statemgr.getAllocator()) {}
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virtual const GRState* Assume(const GRState* St, SVal Cond,
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bool Assumption, bool& isFeasible);
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const GRState* Assume(const GRState* St, Loc Cond, bool Assumption,
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bool& isFeasible);
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const GRState* AssumeAux(const GRState* St, Loc Cond,bool Assumption,
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bool& isFeasible);
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const GRState* Assume(const GRState* St, NonLoc Cond, bool Assumption,
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bool& isFeasible);
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const GRState* AssumeAux(const GRState* St, NonLoc Cond, bool Assumption,
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bool& isFeasible);
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const GRState* AssumeSymInt(const GRState* St, bool Assumption,
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const SymIntConstraint& C, bool& isFeasible);
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const GRState* AssumeSymNE(const GRState* St, SymbolID sym,
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const llvm::APSInt& V, bool& isFeasible);
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const GRState* AssumeSymEQ(const GRState* St, SymbolID sym,
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const llvm::APSInt& V, bool& isFeasible);
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const GRState* AssumeSymLT(const GRState* St, SymbolID sym,
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const llvm::APSInt& V, bool& isFeasible);
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const GRState* AssumeSymGT(const GRState* St, SymbolID sym,
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const llvm::APSInt& V, bool& isFeasible);
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const GRState* AssumeSymGE(const GRState* St, SymbolID sym,
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const llvm::APSInt& V, bool& isFeasible);
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const GRState* AssumeSymLE(const GRState* St, SymbolID sym,
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const llvm::APSInt& V, bool& isFeasible);
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const GRState* AssumeInBound(const GRState* St, SVal Idx, SVal UpperBound,
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bool Assumption, bool& isFeasible);
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const GRState* AddEQ(const GRState* St, SymbolID sym, const llvm::APSInt& V);
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const GRState* AddNE(const GRState* St, SymbolID sym, const llvm::APSInt& V);
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const llvm::APSInt* getSymVal(const GRState* St, SymbolID sym);
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bool isNotEqual(const GRState* St, SymbolID sym, const llvm::APSInt& V) const;
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bool isEqual(const GRState* St, SymbolID sym, const llvm::APSInt& V) const;
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const GRState* RemoveDeadBindings(const GRState* St,
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StoreManager::LiveSymbolsTy& LSymbols,
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StoreManager::DeadSymbolsTy& DSymbols);
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void print(const GRState* St, std::ostream& Out,
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const char* nl, const char *sep);
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private:
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BasicValueFactory& getBasicVals() { return StateMgr.getBasicVals(); }
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};
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} // end anonymous namespace
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ConstraintManager* clang::CreateBasicConstraintManager(GRStateManager& StateMgr)
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{
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return new BasicConstraintManager(StateMgr);
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}
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const GRState* BasicConstraintManager::Assume(const GRState* St, SVal Cond,
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bool Assumption, bool& isFeasible) {
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if (Cond.isUnknown()) {
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isFeasible = true;
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return St;
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}
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if (isa<NonLoc>(Cond))
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return Assume(St, cast<NonLoc>(Cond), Assumption, isFeasible);
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else
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return Assume(St, cast<Loc>(Cond), Assumption, isFeasible);
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}
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const GRState* BasicConstraintManager::Assume(const GRState* St, Loc Cond,
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bool Assumption, bool& isFeasible) {
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St = AssumeAux(St, Cond, Assumption, isFeasible);
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// TF->EvalAssume(*this, St, Cond, Assumption, isFeasible)
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return St;
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}
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const GRState* BasicConstraintManager::AssumeAux(const GRState* St, Loc Cond,
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bool Assumption, bool& isFeasible) {
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BasicValueFactory& BasicVals = StateMgr.getBasicVals();
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switch (Cond.getSubKind()) {
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default:
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assert (false && "'Assume' not implemented for this Loc.");
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return St;
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case loc::SymbolValKind:
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if (Assumption)
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return AssumeSymNE(St, cast<loc::SymbolVal>(Cond).getSymbol(),
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BasicVals.getZeroWithPtrWidth(), isFeasible);
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else
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return AssumeSymEQ(St, cast<loc::SymbolVal>(Cond).getSymbol(),
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BasicVals.getZeroWithPtrWidth(), isFeasible);
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case loc::MemRegionKind: {
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// FIXME: Should this go into the storemanager?
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const MemRegion* R = cast<loc::MemRegionVal>(Cond).getRegion();
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while (R) {
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if (const SubRegion* SubR = dyn_cast<SubRegion>(R)) {
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R = SubR->getSuperRegion();
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continue;
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}
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else if (const SymbolicRegion* SymR = dyn_cast<SymbolicRegion>(R))
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return AssumeAux(St, loc::SymbolVal(SymR->getSymbol()), Assumption,
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isFeasible);
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break;
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}
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// FALL-THROUGH.
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}
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case loc::FuncValKind:
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case loc::GotoLabelKind:
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isFeasible = Assumption;
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return St;
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case loc::ConcreteIntKind: {
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bool b = cast<loc::ConcreteInt>(Cond).getValue() != 0;
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isFeasible = b ? Assumption : !Assumption;
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return St;
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}
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} // end switch
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}
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const GRState*
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BasicConstraintManager::Assume(const GRState* St, NonLoc Cond, bool Assumption,
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bool& isFeasible) {
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St = AssumeAux(St, Cond, Assumption, isFeasible);
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// TF->EvalAssume() does nothing now.
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return St;
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}
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const GRState*
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BasicConstraintManager::AssumeAux(const GRState* St,NonLoc Cond,
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bool Assumption, bool& isFeasible) {
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BasicValueFactory& BasicVals = StateMgr.getBasicVals();
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SymbolManager& SymMgr = StateMgr.getSymbolManager();
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switch (Cond.getSubKind()) {
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default:
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assert(false && "'Assume' not implemented for this NonLoc");
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case nonloc::SymbolValKind: {
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nonloc::SymbolVal& SV = cast<nonloc::SymbolVal>(Cond);
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SymbolID sym = SV.getSymbol();
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if (Assumption)
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return AssumeSymNE(St, sym, BasicVals.getValue(0, SymMgr.getType(sym)),
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isFeasible);
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else
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return AssumeSymEQ(St, sym, BasicVals.getValue(0, SymMgr.getType(sym)),
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isFeasible);
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}
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case nonloc::SymIntConstraintValKind:
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return
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AssumeSymInt(St, Assumption,
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cast<nonloc::SymIntConstraintVal>(Cond).getConstraint(),
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isFeasible);
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case nonloc::ConcreteIntKind: {
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bool b = cast<nonloc::ConcreteInt>(Cond).getValue() != 0;
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isFeasible = b ? Assumption : !Assumption;
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return St;
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}
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case nonloc::LocAsIntegerKind:
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return AssumeAux(St, cast<nonloc::LocAsInteger>(Cond).getLoc(),
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Assumption, isFeasible);
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} // end switch
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}
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const GRState*
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BasicConstraintManager::AssumeSymInt(const GRState* St, bool Assumption,
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const SymIntConstraint& C, bool& isFeasible) {
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switch (C.getOpcode()) {
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default:
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// No logic yet for other operators.
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isFeasible = true;
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return St;
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case BinaryOperator::EQ:
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if (Assumption)
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return AssumeSymEQ(St, C.getSymbol(), C.getInt(), isFeasible);
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else
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return AssumeSymNE(St, C.getSymbol(), C.getInt(), isFeasible);
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case BinaryOperator::NE:
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if (Assumption)
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return AssumeSymNE(St, C.getSymbol(), C.getInt(), isFeasible);
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else
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return AssumeSymEQ(St, C.getSymbol(), C.getInt(), isFeasible);
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case BinaryOperator::GT:
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if (Assumption)
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return AssumeSymGT(St, C.getSymbol(), C.getInt(), isFeasible);
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else
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return AssumeSymLE(St, C.getSymbol(), C.getInt(), isFeasible);
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case BinaryOperator::GE:
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if (Assumption)
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return AssumeSymGE(St, C.getSymbol(), C.getInt(), isFeasible);
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else
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return AssumeSymLT(St, C.getSymbol(), C.getInt(), isFeasible);
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case BinaryOperator::LT:
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if (Assumption)
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return AssumeSymLT(St, C.getSymbol(), C.getInt(), isFeasible);
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else
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return AssumeSymGE(St, C.getSymbol(), C.getInt(), isFeasible);
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case BinaryOperator::LE:
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if (Assumption)
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return AssumeSymLE(St, C.getSymbol(), C.getInt(), isFeasible);
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else
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return AssumeSymGT(St, C.getSymbol(), C.getInt(), isFeasible);
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} // end switch
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}
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const GRState*
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BasicConstraintManager::AssumeSymNE(const GRState* St, SymbolID sym,
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const llvm::APSInt& V, bool& isFeasible) {
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// First, determine if sym == X, where X != V.
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if (const llvm::APSInt* X = getSymVal(St, sym)) {
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isFeasible = (*X != V);
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return St;
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}
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// Second, determine if sym != V.
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if (isNotEqual(St, sym, V)) {
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isFeasible = true;
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return St;
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}
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// If we reach here, sym is not a constant and we don't know if it is != V.
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// Make that assumption.
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isFeasible = true;
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return AddNE(St, sym, V);
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}
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const GRState*
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BasicConstraintManager::AssumeSymEQ(const GRState* St, SymbolID sym,
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const llvm::APSInt& V, bool& isFeasible) {
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// First, determine if sym == X, where X != V.
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if (const llvm::APSInt* X = getSymVal(St, sym)) {
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isFeasible = *X == V;
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return St;
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}
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// Second, determine if sym != V.
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if (isNotEqual(St, sym, V)) {
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isFeasible = false;
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return St;
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}
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// If we reach here, sym is not a constant and we don't know if it is == V.
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// Make that assumption.
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isFeasible = true;
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return AddEQ(St, sym, V);
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}
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// These logic will be handled in another ConstraintManager.
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const GRState*
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BasicConstraintManager::AssumeSymLT(const GRState* St, SymbolID sym,
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const llvm::APSInt& V, bool& isFeasible) {
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// Is 'V' the smallest possible value?
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if (V == llvm::APSInt::getMinValue(V.getBitWidth(), V.isSigned())) {
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// sym cannot be any value less than 'V'. This path is infeasible.
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isFeasible = false;
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return St;
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}
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// FIXME: For now have assuming x < y be the same as assuming sym != V;
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return AssumeSymNE(St, sym, V, isFeasible);
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}
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const GRState*
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BasicConstraintManager::AssumeSymGT(const GRState* St, SymbolID sym,
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const llvm::APSInt& V, bool& isFeasible) {
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// FIXME: For now have assuming x > y be the same as assuming sym != V;
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return AssumeSymNE(St, sym, V, isFeasible);
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}
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const GRState*
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BasicConstraintManager::AssumeSymGE(const GRState* St, SymbolID sym,
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const llvm::APSInt& V, bool& isFeasible) {
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// Reject a path if the value of sym is a constant X and !(X >= V).
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if (const llvm::APSInt* X = getSymVal(St, sym)) {
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isFeasible = *X >= V;
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return St;
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}
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isFeasible = !isNotEqual(St, sym, V) ||
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(V != llvm::APSInt::getMaxValue(V.getBitWidth(), V.isSigned()));
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return St;
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}
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const GRState*
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BasicConstraintManager::AssumeSymLE(const GRState* St, SymbolID sym,
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const llvm::APSInt& V, bool& isFeasible) {
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// Reject a path if the value of sym is a constant X and !(X <= V).
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if (const llvm::APSInt* X = getSymVal(St, sym)) {
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isFeasible = *X <= V;
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return St;
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}
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// Sym is not a constant, but it is worth looking to see if V is the
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// minimum integer value.
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if (V == llvm::APSInt::getMinValue(V.getBitWidth(), V.isSigned())) {
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// If we know that sym != V, then this condition is infeasible since
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// there is no other value less than V.
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isFeasible = !isNotEqual(St, sym, V);
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// If the path is still feasible then as a consequence we know that
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// 'sym == V' because we cannot have 'sym < V' (no smaller values).
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// Add this constraint.
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if (isFeasible)
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return AddEQ(St, sym, V);
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}
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else
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isFeasible = true;
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return St;
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}
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const GRState*
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BasicConstraintManager::AssumeInBound(const GRState* St, SVal Idx,
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SVal UpperBound, bool Assumption,
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bool& isFeasible) {
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// Only support ConcreteInt for now.
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if (!(isa<nonloc::ConcreteInt>(Idx) && isa<nonloc::ConcreteInt>(UpperBound))){
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isFeasible = true;
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return St;
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}
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const llvm::APSInt& Zero = getBasicVals().getZeroWithPtrWidth(false);
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llvm::APSInt IdxV = cast<nonloc::ConcreteInt>(Idx).getValue();
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// IdxV might be too narrow.
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if (IdxV.getBitWidth() < Zero.getBitWidth())
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IdxV.extend(Zero.getBitWidth());
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// UBV might be too narrow, too.
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llvm::APSInt UBV = cast<nonloc::ConcreteInt>(UpperBound).getValue();
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if (UBV.getBitWidth() < Zero.getBitWidth())
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UBV.extend(Zero.getBitWidth());
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bool InBound = (Zero <= IdxV) && (IdxV < UBV);
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isFeasible = Assumption ? InBound : !InBound;
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return St;
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}
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static int ConstEqTyIndex = 0;
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static int ConstNotEqTyIndex = 0;
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namespace clang {
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template<>
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struct GRStateTrait<ConstNotEqTy> : public GRStatePartialTrait<ConstNotEqTy> {
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static inline void* GDMIndex() { return &ConstNotEqTyIndex; }
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};
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template<>
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struct GRStateTrait<ConstEqTy> : public GRStatePartialTrait<ConstEqTy> {
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static inline void* GDMIndex() { return &ConstEqTyIndex; }
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};
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}
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const GRState* BasicConstraintManager::AddEQ(const GRState* St, SymbolID sym,
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const llvm::APSInt& V) {
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// Create a new state with the old binding replaced.
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GRStateRef state(St, StateMgr);
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return state.set<ConstEqTy>(sym, &V);
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}
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const GRState* BasicConstraintManager::AddNE(const GRState* St, SymbolID sym,
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const llvm::APSInt& V) {
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GRStateRef state(St, StateMgr);
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// First, retrieve the NE-set associated with the given symbol.
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ConstNotEqTy::data_type* T = state.get<ConstNotEqTy>(sym);
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GRState::IntSetTy S = T ? *T : ISetFactory.GetEmptySet();
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// Now add V to the NE set.
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S = ISetFactory.Add(S, &V);
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// Create a new state with the old binding replaced.
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return state.set<ConstNotEqTy>(sym, S);
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}
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const llvm::APSInt* BasicConstraintManager::getSymVal(const GRState* St,
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SymbolID sym) {
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const ConstEqTy::data_type* T = St->get<ConstEqTy>(sym);
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return T ? *T : NULL;
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}
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bool BasicConstraintManager::isNotEqual(const GRState* St, SymbolID sym,
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const llvm::APSInt& V) const {
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// Retrieve the NE-set associated with the given symbol.
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const ConstNotEqTy::data_type* T = St->get<ConstNotEqTy>(sym);
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// See if V is present in the NE-set.
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return T ? T->contains(&V) : false;
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}
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bool BasicConstraintManager::isEqual(const GRState* St, SymbolID sym,
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const llvm::APSInt& V) const {
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// Retrieve the EQ-set associated with the given symbol.
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const ConstEqTy::data_type* T = St->get<ConstEqTy>(sym);
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// See if V is present in the EQ-set.
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return T ? **T == V : false;
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}
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/// Scan all symbols referenced by the constraints. If the symbol is not alive
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/// as marked in LSymbols, mark it as dead in DSymbols.
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const GRState* BasicConstraintManager::RemoveDeadBindings(const GRState* St,
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StoreManager::LiveSymbolsTy& LSymbols,
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StoreManager::DeadSymbolsTy& DSymbols) {
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GRStateRef state(St, StateMgr);
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ConstEqTy CE = state.get<ConstEqTy>();
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ConstEqTy::Factory& CEFactory = state.get_context<ConstEqTy>();
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for (ConstEqTy::iterator I = CE.begin(), E = CE.end(); I!=E; ++I) {
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SymbolID sym = I.getKey();
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if (!LSymbols.count(sym)) {
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DSymbols.insert(sym);
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CE = CEFactory.Remove(CE, sym);
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}
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}
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state = state.set<ConstEqTy>(CE);
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ConstNotEqTy CNE = state.get<ConstNotEqTy>();
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ConstNotEqTy::Factory& CNEFactory = state.get_context<ConstNotEqTy>();
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for (ConstNotEqTy::iterator I = CNE.begin(), E = CNE.end(); I != E; ++I) {
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SymbolID sym = I.getKey();
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if (!LSymbols.count(sym)) {
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DSymbols.insert(sym);
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CNE = CNEFactory.Remove(CNE, sym);
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}
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}
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return state.set<ConstNotEqTy>(CNE);
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}
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|
|
|
void BasicConstraintManager::print(const GRState* St, std::ostream& Out,
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|
const char* nl, const char *sep) {
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|
// Print equality constraints.
|
|
|
|
ConstEqTy CE = St->get<ConstEqTy>();
|
|
|
|
if (!CE.isEmpty()) {
|
|
Out << nl << sep << "'==' constraints:";
|
|
|
|
for (ConstEqTy::iterator I = CE.begin(), E = CE.end(); I!=E; ++I) {
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|
Out << nl << " $" << I.getKey();
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|
llvm::raw_os_ostream OS(Out);
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|
OS << " : " << *I.getData();
|
|
}
|
|
}
|
|
|
|
// Print != constraints.
|
|
|
|
ConstNotEqTy CNE = St->get<ConstNotEqTy>();
|
|
|
|
if (!CNE.isEmpty()) {
|
|
Out << nl << sep << "'!=' constraints:";
|
|
|
|
for (ConstNotEqTy::iterator I = CNE.begin(), EI = CNE.end(); I!=EI; ++I) {
|
|
Out << nl << " $" << I.getKey() << " : ";
|
|
bool isFirst = true;
|
|
|
|
GRState::IntSetTy::iterator J = I.getData().begin(),
|
|
EJ = I.getData().end();
|
|
|
|
for ( ; J != EJ; ++J) {
|
|
if (isFirst) isFirst = false;
|
|
else Out << ", ";
|
|
|
|
Out << (*J)->getSExtValue(); // Hack: should print to raw_ostream.
|
|
}
|
|
}
|
|
}
|
|
}
|