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_STATICANALYZER_CORE_PATHSENSITIVE_CONSTRAINTMANAGER_H
15 #define LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_CONSTRAINTMANAGER_H
17 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
18 #include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
19 #include "llvm/Support/SaveAndRestore.h"
30 class ConditionTruthVal {
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.
82 // This check is expensive and should be disabled even in Release+Asserts
84 // FIXME: __OPTIMIZE__ is a GNU extension that Clang implements but MSVC
85 // does not. Is there a good equivalent there?
86 assert(assume(State, Cond, false) && "System is over constrained.");
88 return ProgramStatePair((ProgramStateRef)nullptr, State);
91 ProgramStateRef StFalse = assume(State, Cond, false);
93 // We are careful to return the original state, /not/ StTrue,
94 // because we want to avoid having callers generate a new node
95 // in the ExplodedGraph.
96 return ProgramStatePair(State, (ProgramStateRef)nullptr);
99 return ProgramStatePair(StTrue, StFalse);
102 virtual ProgramStateRef assumeInclusiveRange(ProgramStateRef State,
104 const llvm::APSInt &From,
105 const llvm::APSInt &To,
108 virtual ProgramStatePair assumeInclusiveRangeDual(ProgramStateRef State,
110 const llvm::APSInt &From,
111 const llvm::APSInt &To) {
112 ProgramStateRef StInRange =
113 assumeInclusiveRange(State, Value, From, To, true);
115 // If StTrue is infeasible, asserting the falseness of Cond is unnecessary
116 // because the existing constraints already establish this.
118 return ProgramStatePair((ProgramStateRef)nullptr, State);
120 ProgramStateRef StOutOfRange =
121 assumeInclusiveRange(State, Value, From, To, false);
123 // We are careful to return the original state, /not/ StTrue,
124 // because we want to avoid having callers generate a new node
125 // in the ExplodedGraph.
126 return ProgramStatePair(State, (ProgramStateRef)nullptr);
129 return ProgramStatePair(StInRange, StOutOfRange);
132 /// \brief If a symbol is perfectly constrained to a constant, attempt
133 /// to return the concrete value.
135 /// Note that a ConstraintManager is not obligated to return a concretized
136 /// value for a symbol, even if it is perfectly constrained.
137 virtual const llvm::APSInt* getSymVal(ProgramStateRef state,
138 SymbolRef sym) const {
142 virtual ProgramStateRef removeDeadBindings(ProgramStateRef state,
143 SymbolReaper& SymReaper) = 0;
145 virtual void print(ProgramStateRef state,
148 const char *sep) = 0;
150 virtual void EndPath(ProgramStateRef state) {}
152 /// Convenience method to query the state to see if a symbol is null or
153 /// not null, or if neither assumption can be made.
154 ConditionTruthVal isNull(ProgramStateRef State, SymbolRef Sym) {
155 SaveAndRestore<bool> DisableNotify(NotifyAssumeClients, false);
157 return checkNull(State, Sym);
161 /// A flag to indicate that clients should be notified of assumptions.
162 /// By default this is the case, but sometimes this needs to be restricted
163 /// to avoid infinite recursions within the ConstraintManager.
165 /// Note that this flag allows the ConstraintManager to be re-entrant,
166 /// but not thread-safe.
167 bool NotifyAssumeClients;
169 /// canReasonAbout - Not all ConstraintManagers can accurately reason about
170 /// all SVal values. This method returns true if the ConstraintManager can
171 /// reasonably handle a given SVal value. This is typically queried by
172 /// ExprEngine to determine if the value should be replaced with a
173 /// conjured symbolic value in order to recover some precision.
174 virtual bool canReasonAbout(SVal X) const = 0;
176 /// Returns whether or not a symbol is known to be null ("true"), known to be
177 /// non-null ("false"), or may be either ("underconstrained").
178 virtual ConditionTruthVal checkNull(ProgramStateRef State, SymbolRef Sym);
181 std::unique_ptr<ConstraintManager>
182 CreateRangeConstraintManager(ProgramStateManager &statemgr,
183 SubEngine *subengine);
185 } // end GR namespace
187 } // end clang namespace