| //== BasicConstraintManager.cpp - Manage basic constraints.------*- 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 BasicConstraintManager, a class that tracks simple |
| // equality and inequality constraints on symbolic values of GRState. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "SimpleConstraintManager.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/GRState.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/GRStateTrait.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/TransferFuncs.h" |
| #include "llvm/Support/raw_ostream.h" |
| |
| using namespace clang; |
| using namespace ento; |
| |
| |
| namespace { class ConstNotEq {}; } |
| namespace { class ConstEq {}; } |
| |
| typedef llvm::ImmutableMap<SymbolRef,GRState::IntSetTy> ConstNotEqTy; |
| typedef llvm::ImmutableMap<SymbolRef,const llvm::APSInt*> ConstEqTy; |
| |
| static int ConstEqIndex = 0; |
| static int ConstNotEqIndex = 0; |
| |
| namespace clang { |
| namespace ento { |
| template<> |
| struct GRStateTrait<ConstNotEq> : public GRStatePartialTrait<ConstNotEqTy> { |
| static inline void *GDMIndex() { return &ConstNotEqIndex; } |
| }; |
| |
| template<> |
| struct GRStateTrait<ConstEq> : public GRStatePartialTrait<ConstEqTy> { |
| static inline void *GDMIndex() { return &ConstEqIndex; } |
| }; |
| } |
| } |
| |
| namespace { |
| // BasicConstraintManager only tracks equality and inequality constraints of |
| // constants and integer variables. |
| class BasicConstraintManager |
| : public SimpleConstraintManager { |
| GRState::IntSetTy::Factory ISetFactory; |
| public: |
| BasicConstraintManager(GRStateManager &statemgr, SubEngine &subengine) |
| : SimpleConstraintManager(subengine), |
| ISetFactory(statemgr.getAllocator()) {} |
| |
| const GRState *assumeSymNE(const GRState *state, SymbolRef sym, |
| const llvm::APSInt& V, |
| const llvm::APSInt& Adjustment); |
| |
| const GRState *assumeSymEQ(const GRState *state, SymbolRef sym, |
| const llvm::APSInt& V, |
| const llvm::APSInt& Adjustment); |
| |
| const GRState *assumeSymLT(const GRState *state, SymbolRef sym, |
| const llvm::APSInt& V, |
| const llvm::APSInt& Adjustment); |
| |
| const GRState *assumeSymGT(const GRState *state, SymbolRef sym, |
| const llvm::APSInt& V, |
| const llvm::APSInt& Adjustment); |
| |
| const GRState *assumeSymGE(const GRState *state, SymbolRef sym, |
| const llvm::APSInt& V, |
| const llvm::APSInt& Adjustment); |
| |
| const GRState *assumeSymLE(const GRState *state, SymbolRef sym, |
| const llvm::APSInt& V, |
| const llvm::APSInt& Adjustment); |
| |
| const GRState *AddEQ(const GRState *state, SymbolRef sym, const llvm::APSInt& V); |
| |
| const GRState *AddNE(const GRState *state, SymbolRef sym, const llvm::APSInt& V); |
| |
| const llvm::APSInt* getSymVal(const GRState *state, SymbolRef sym) const; |
| bool isNotEqual(const GRState *state, SymbolRef sym, const llvm::APSInt& V) |
| const; |
| bool isEqual(const GRState *state, SymbolRef sym, const llvm::APSInt& V) |
| const; |
| |
| const GRState *removeDeadBindings(const GRState *state, SymbolReaper& SymReaper); |
| |
| void print(const GRState *state, raw_ostream &Out, |
| const char* nl, const char *sep); |
| }; |
| |
| } // end anonymous namespace |
| |
| ConstraintManager* ento::CreateBasicConstraintManager(GRStateManager& statemgr, |
| SubEngine &subengine) { |
| return new BasicConstraintManager(statemgr, subengine); |
| } |
| |
| |
| const GRState* |
| BasicConstraintManager::assumeSymNE(const GRState *state, SymbolRef sym, |
| const llvm::APSInt &V, |
| const llvm::APSInt &Adjustment) { |
| // First, determine if sym == X, where X+Adjustment != V. |
| llvm::APSInt Adjusted = V-Adjustment; |
| if (const llvm::APSInt* X = getSymVal(state, sym)) { |
| bool isFeasible = (*X != Adjusted); |
| return isFeasible ? state : NULL; |
| } |
| |
| // Second, determine if sym+Adjustment != V. |
| if (isNotEqual(state, sym, Adjusted)) |
| return state; |
| |
| // If we reach here, sym is not a constant and we don't know if it is != V. |
| // Make that assumption. |
| return AddNE(state, sym, Adjusted); |
| } |
| |
| const GRState* |
| BasicConstraintManager::assumeSymEQ(const GRState *state, SymbolRef sym, |
| const llvm::APSInt &V, |
| const llvm::APSInt &Adjustment) { |
| // First, determine if sym == X, where X+Adjustment != V. |
| llvm::APSInt Adjusted = V-Adjustment; |
| if (const llvm::APSInt* X = getSymVal(state, sym)) { |
| bool isFeasible = (*X == Adjusted); |
| return isFeasible ? state : NULL; |
| } |
| |
| // Second, determine if sym+Adjustment != V. |
| if (isNotEqual(state, sym, Adjusted)) |
| return NULL; |
| |
| // If we reach here, sym is not a constant and we don't know if it is == V. |
| // Make that assumption. |
| return AddEQ(state, sym, Adjusted); |
| } |
| |
| // The logic for these will be handled in another ConstraintManager. |
| const GRState* |
| BasicConstraintManager::assumeSymLT(const GRState *state, SymbolRef sym, |
| const llvm::APSInt &V, |
| const llvm::APSInt &Adjustment) { |
| // Is 'V' the smallest possible value? |
| if (V == llvm::APSInt::getMinValue(V.getBitWidth(), V.isUnsigned())) { |
| // sym cannot be any value less than 'V'. This path is infeasible. |
| return NULL; |
| } |
| |
| // FIXME: For now have assuming x < y be the same as assuming sym != V; |
| return assumeSymNE(state, sym, V, Adjustment); |
| } |
| |
| const GRState* |
| BasicConstraintManager::assumeSymGT(const GRState *state, SymbolRef sym, |
| const llvm::APSInt &V, |
| const llvm::APSInt &Adjustment) { |
| // Is 'V' the largest possible value? |
| if (V == llvm::APSInt::getMaxValue(V.getBitWidth(), V.isUnsigned())) { |
| // sym cannot be any value greater than 'V'. This path is infeasible. |
| return NULL; |
| } |
| |
| // FIXME: For now have assuming x > y be the same as assuming sym != V; |
| return assumeSymNE(state, sym, V, Adjustment); |
| } |
| |
| const GRState* |
| BasicConstraintManager::assumeSymGE(const GRState *state, SymbolRef sym, |
| const llvm::APSInt &V, |
| const llvm::APSInt &Adjustment) { |
| // Reject a path if the value of sym is a constant X and !(X+Adj >= V). |
| if (const llvm::APSInt *X = getSymVal(state, sym)) { |
| bool isFeasible = (*X >= V-Adjustment); |
| return isFeasible ? state : NULL; |
| } |
| |
| // Sym is not a constant, but it is worth looking to see if V is the |
| // maximum integer value. |
| if (V == llvm::APSInt::getMaxValue(V.getBitWidth(), V.isUnsigned())) { |
| llvm::APSInt Adjusted = V-Adjustment; |
| |
| // If we know that sym != V (after adjustment), then this condition |
| // is infeasible since there is no other value greater than V. |
| bool isFeasible = !isNotEqual(state, sym, Adjusted); |
| |
| // If the path is still feasible then as a consequence we know that |
| // 'sym+Adjustment == V' because there are no larger values. |
| // Add this constraint. |
| return isFeasible ? AddEQ(state, sym, Adjusted) : NULL; |
| } |
| |
| return state; |
| } |
| |
| const GRState* |
| BasicConstraintManager::assumeSymLE(const GRState *state, SymbolRef sym, |
| const llvm::APSInt &V, |
| const llvm::APSInt &Adjustment) { |
| // Reject a path if the value of sym is a constant X and !(X+Adj <= V). |
| if (const llvm::APSInt* X = getSymVal(state, sym)) { |
| bool isFeasible = (*X <= V-Adjustment); |
| return isFeasible ? state : NULL; |
| } |
| |
| // Sym is not a constant, but it is worth looking to see if V is the |
| // minimum integer value. |
| if (V == llvm::APSInt::getMinValue(V.getBitWidth(), V.isUnsigned())) { |
| llvm::APSInt Adjusted = V-Adjustment; |
| |
| // If we know that sym != V (after adjustment), then this condition |
| // is infeasible since there is no other value less than V. |
| bool isFeasible = !isNotEqual(state, sym, Adjusted); |
| |
| // If the path is still feasible then as a consequence we know that |
| // 'sym+Adjustment == V' because there are no smaller values. |
| // Add this constraint. |
| return isFeasible ? AddEQ(state, sym, Adjusted) : NULL; |
| } |
| |
| return state; |
| } |
| |
| const GRState *BasicConstraintManager::AddEQ(const GRState *state, SymbolRef sym, |
| const llvm::APSInt& V) { |
| // Create a new state with the old binding replaced. |
| return state->set<ConstEq>(sym, &state->getBasicVals().getValue(V)); |
| } |
| |
| const GRState *BasicConstraintManager::AddNE(const GRState *state, SymbolRef sym, |
| const llvm::APSInt& V) { |
| |
| // First, retrieve the NE-set associated with the given symbol. |
| ConstNotEqTy::data_type* T = state->get<ConstNotEq>(sym); |
| GRState::IntSetTy S = T ? *T : ISetFactory.getEmptySet(); |
| |
| // Now add V to the NE set. |
| S = ISetFactory.add(S, &state->getBasicVals().getValue(V)); |
| |
| // Create a new state with the old binding replaced. |
| return state->set<ConstNotEq>(sym, S); |
| } |
| |
| const llvm::APSInt* BasicConstraintManager::getSymVal(const GRState *state, |
| SymbolRef sym) const { |
| const ConstEqTy::data_type* T = state->get<ConstEq>(sym); |
| return T ? *T : NULL; |
| } |
| |
| bool BasicConstraintManager::isNotEqual(const GRState *state, SymbolRef sym, |
| const llvm::APSInt& V) const { |
| |
| // Retrieve the NE-set associated with the given symbol. |
| const ConstNotEqTy::data_type* T = state->get<ConstNotEq>(sym); |
| |
| // See if V is present in the NE-set. |
| return T ? T->contains(&state->getBasicVals().getValue(V)) : false; |
| } |
| |
| bool BasicConstraintManager::isEqual(const GRState *state, SymbolRef sym, |
| const llvm::APSInt& V) const { |
| // Retrieve the EQ-set associated with the given symbol. |
| const ConstEqTy::data_type* T = state->get<ConstEq>(sym); |
| // See if V is present in the EQ-set. |
| return T ? **T == V : false; |
| } |
| |
| /// Scan all symbols referenced by the constraints. If the symbol is not alive |
| /// as marked in LSymbols, mark it as dead in DSymbols. |
| const GRState* |
| BasicConstraintManager::removeDeadBindings(const GRState *state, |
| SymbolReaper& SymReaper) { |
| |
| ConstEqTy CE = state->get<ConstEq>(); |
| ConstEqTy::Factory& CEFactory = state->get_context<ConstEq>(); |
| |
| for (ConstEqTy::iterator I = CE.begin(), E = CE.end(); I!=E; ++I) { |
| SymbolRef sym = I.getKey(); |
| if (SymReaper.maybeDead(sym)) |
| CE = CEFactory.remove(CE, sym); |
| } |
| state = state->set<ConstEq>(CE); |
| |
| ConstNotEqTy CNE = state->get<ConstNotEq>(); |
| ConstNotEqTy::Factory& CNEFactory = state->get_context<ConstNotEq>(); |
| |
| for (ConstNotEqTy::iterator I = CNE.begin(), E = CNE.end(); I != E; ++I) { |
| SymbolRef sym = I.getKey(); |
| if (SymReaper.maybeDead(sym)) |
| CNE = CNEFactory.remove(CNE, sym); |
| } |
| |
| return state->set<ConstNotEq>(CNE); |
| } |
| |
| void BasicConstraintManager::print(const GRState *state, raw_ostream &Out, |
| const char* nl, const char *sep) { |
| // Print equality constraints. |
| |
| ConstEqTy CE = state->get<ConstEq>(); |
| |
| if (!CE.isEmpty()) { |
| Out << nl << sep << "'==' constraints:"; |
| for (ConstEqTy::iterator I = CE.begin(), E = CE.end(); I!=E; ++I) |
| Out << nl << " $" << I.getKey() << " : " << *I.getData(); |
| } |
| |
| // Print != constraints. |
| |
| ConstNotEqTy CNE = state->get<ConstNotEq>(); |
| |
| 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. |
| } |
| } |
| } |
| } |