| //== 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/Analysis/PathSensitive/GRState.h" |
| #include "clang/Analysis/PathSensitive/GRStateTrait.h" |
| #include "clang/Analysis/PathSensitive/GRTransferFuncs.h" |
| #include "llvm/Support/raw_ostream.h" |
| |
| using namespace clang; |
| |
| |
| 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 { |
| 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, GRSubEngine &subengine) |
| : SimpleConstraintManager(subengine), |
| ISetFactory(statemgr.getAllocator()) {} |
| |
| const GRState* AssumeSymNE(const GRState* state, SymbolRef sym, |
| const llvm::APSInt& V); |
| |
| const GRState* AssumeSymEQ(const GRState* state, SymbolRef sym, |
| const llvm::APSInt& V); |
| |
| const GRState* AssumeSymLT(const GRState* state, SymbolRef sym, |
| const llvm::APSInt& V); |
| |
| const GRState* AssumeSymGT(const GRState* state, SymbolRef sym, |
| const llvm::APSInt& V); |
| |
| const GRState* AssumeSymGE(const GRState* state, SymbolRef sym, |
| const llvm::APSInt& V); |
| |
| const GRState* AssumeSymLE(const GRState* state, SymbolRef sym, |
| const llvm::APSInt& V); |
| |
| 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, llvm::raw_ostream& Out, |
| const char* nl, const char *sep); |
| }; |
| |
| } // end anonymous namespace |
| |
| ConstraintManager* clang::CreateBasicConstraintManager(GRStateManager& statemgr, |
| GRSubEngine &subengine) { |
| return new BasicConstraintManager(statemgr, subengine); |
| } |
| |
| const GRState* |
| BasicConstraintManager::AssumeSymNE(const GRState *state, SymbolRef sym, |
| const llvm::APSInt& V) { |
| // First, determine if sym == X, where X != V. |
| if (const llvm::APSInt* X = getSymVal(state, sym)) { |
| bool isFeasible = (*X != V); |
| return isFeasible ? state : NULL; |
| } |
| |
| // Second, determine if sym != V. |
| if (isNotEqual(state, sym, V)) |
| 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, V); |
| } |
| |
| const GRState *BasicConstraintManager::AssumeSymEQ(const GRState *state, |
| SymbolRef sym, |
| const llvm::APSInt &V) { |
| // First, determine if sym == X, where X != V. |
| if (const llvm::APSInt* X = getSymVal(state, sym)) { |
| bool isFeasible = *X == V; |
| return isFeasible ? state : NULL; |
| } |
| |
| // Second, determine if sym != V. |
| if (isNotEqual(state, sym, V)) |
| 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, V); |
| } |
| |
| // These logic will be handled in another ConstraintManager. |
| const GRState *BasicConstraintManager::AssumeSymLT(const GRState *state, |
| SymbolRef sym, |
| const llvm::APSInt& V) { |
| // 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); |
| } |
| |
| const GRState *BasicConstraintManager::AssumeSymGT(const GRState *state, |
| SymbolRef sym, |
| const llvm::APSInt& V) { |
| |
| // 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); |
| } |
| |
| const GRState *BasicConstraintManager::AssumeSymGE(const GRState *state, |
| SymbolRef sym, |
| const llvm::APSInt &V) { |
| |
| // Reject a path if the value of sym is a constant X and !(X >= V). |
| if (const llvm::APSInt *X = getSymVal(state, sym)) { |
| bool isFeasible = *X >= V; |
| 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())) { |
| // If we know that sym != V, then this condition is infeasible since |
| // there is no other value greater than V. |
| bool isFeasible = !isNotEqual(state, sym, V); |
| |
| // If the path is still feasible then as a consequence we know that |
| // 'sym == V' because we cannot have 'sym > V' (no larger values). |
| // Add this constraint. |
| return isFeasible ? AddEQ(state, sym, V) : NULL; |
| } |
| |
| return state; |
| } |
| |
| const GRState* |
| BasicConstraintManager::AssumeSymLE(const GRState* state, SymbolRef sym, |
| const llvm::APSInt& V) { |
| |
| // Reject a path if the value of sym is a constant X and !(X <= V). |
| if (const llvm::APSInt* X = getSymVal(state, sym)) { |
| bool isFeasible = *X <= V; |
| 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())) { |
| // If we know that sym != V, then this condition is infeasible since |
| // there is no other value less than V. |
| bool isFeasible = !isNotEqual(state, sym, V); |
| |
| // If the path is still feasible then as a consequence we know that |
| // 'sym == V' because we cannot have 'sym < V' (no smaller values). |
| // Add this constraint. |
| return isFeasible ? AddEQ(state, sym, V) : 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, &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, &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(&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, llvm::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. |
| } |
| } |
| } |
| } |