1 //== ConstraintManager.h - Constraints on symbolic values.-------*- C++ -*--==//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defined the interface to manage constraints on symbolic values.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CLANG_GR_CONSTRAINT_MANAGER_H
15 #define LLVM_CLANG_GR_CONSTRAINT_MANAGER_H
17 #include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
18 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
19 #include "llvm/Support/SaveAndRestore.h"
30 class ConditionTruthVal {
31 llvm::Optional<bool> Val;
33 /// Construct a ConditionTruthVal indicating the constraint is constrained
34 /// to either true or false, depending on the boolean value provided.
35 ConditionTruthVal(bool constraint) : Val(constraint) {}
37 /// Construct a ConstraintVal indicating the constraint is underconstrained.
38 ConditionTruthVal() {}
40 /// Return true if the constraint is perfectly constrained to 'true'.
41 bool isConstrainedTrue() const {
42 return Val.hasValue() && Val.getValue();
45 /// Return true if the constraint is perfectly constrained to 'false'.
46 bool isConstrainedFalse() const {
47 return Val.hasValue() && !Val.getValue();
50 /// Return true if the constrained is perfectly constrained.
51 bool isConstrained() const {
52 return Val.hasValue();
55 /// Return true if the constrained is underconstrained and we do not know
56 /// if the constraint is true of value.
57 bool isUnderconstrained() const {
58 return !Val.hasValue();
62 class ConstraintManager {
64 ConstraintManager() : NotifyAssumeClients(true) {}
66 virtual ~ConstraintManager();
67 virtual ProgramStateRef assume(ProgramStateRef state,
71 typedef std::pair<ProgramStateRef, ProgramStateRef> ProgramStatePair;
73 /// Returns a pair of states (StTrue, StFalse) where the given condition is
74 /// assumed to be true or false, respectively.
75 ProgramStatePair assumeDual(ProgramStateRef State, DefinedSVal Cond) {
76 ProgramStateRef StTrue = assume(State, Cond, true);
78 // If StTrue is infeasible, asserting the falseness of Cond is unnecessary
79 // because the existing constraints already establish this.
81 // FIXME: This is fairly expensive and should be disabled even in
82 // Release+Asserts builds.
83 assert(assume(State, Cond, false) && "System is over constrained.");
84 return ProgramStatePair((ProgramStateRef)NULL, State);
87 ProgramStateRef StFalse = assume(State, Cond, false);
89 // We are careful to return the original state, /not/ StTrue,
90 // because we want to avoid having callers generate a new node
91 // in the ExplodedGraph.
92 return ProgramStatePair(State, (ProgramStateRef)NULL);
95 return ProgramStatePair(StTrue, StFalse);
98 /// \brief If a symbol is perfectly constrained to a constant, attempt
99 /// to return the concrete value.
101 /// Note that a ConstraintManager is not obligated to return a concretized
102 /// value for a symbol, even if it is perfectly constrained.
103 virtual const llvm::APSInt* getSymVal(ProgramStateRef state,
104 SymbolRef sym) const {
108 virtual ProgramStateRef removeDeadBindings(ProgramStateRef state,
109 SymbolReaper& SymReaper) = 0;
111 virtual void print(ProgramStateRef state,
114 const char *sep) = 0;
116 virtual void EndPath(ProgramStateRef state) {}
118 /// Convenience method to query the state to see if a symbol is null or
119 /// not null, or if neither assumption can be made.
120 ConditionTruthVal isNull(ProgramStateRef State, SymbolRef Sym) {
121 llvm::SaveAndRestore<bool> DisableNotify(NotifyAssumeClients, false);
123 return checkNull(State, Sym);
127 /// A flag to indicate that clients should be notified of assumptions.
128 /// By default this is the case, but sometimes this needs to be restricted
129 /// to avoid infinite recursions within the ConstraintManager.
131 /// Note that this flag allows the ConstraintManager to be re-entrant,
132 /// but not thread-safe.
133 bool NotifyAssumeClients;
135 /// canReasonAbout - Not all ConstraintManagers can accurately reason about
136 /// all SVal values. This method returns true if the ConstraintManager can
137 /// reasonably handle a given SVal value. This is typically queried by
138 /// ExprEngine to determine if the value should be replaced with a
139 /// conjured symbolic value in order to recover some precision.
140 virtual bool canReasonAbout(SVal X) const = 0;
142 /// Returns whether or not a symbol is known to be null ("true"), known to be
143 /// non-null ("false"), or may be either ("underconstrained").
144 virtual ConditionTruthVal checkNull(ProgramStateRef State, SymbolRef Sym);
147 ConstraintManager* CreateRangeConstraintManager(ProgramStateManager& statemgr,
148 SubEngine *subengine);
150 } // end GR namespace
152 } // end clang namespace