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Closed by commit rGf26deb4e6ba7: [analyzer][solver][NFC] Introduce
ConstraintAssignor (authored by vsavchenko).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D105692/new/
https://reviews.llvm.org/D105692
Files:
clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
Index: clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
===================================================================
--- clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
+++ clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
@@ -669,6 +669,17 @@
return getConstraint(State, EquivalenceClass::find(State, Sym));
}
+LLVM_NODISCARD ProgramStateRef setConstraint(ProgramStateRef State,
+ EquivalenceClass Class,
+ RangeSet Constraint) {
+ return State->set<ConstraintRange>(Class, Constraint);
+}
+
+LLVM_NODISCARD ProgramStateRef setConstraints(ProgramStateRef State,
+ ConstraintRangeTy Constraints) {
+ return State->set<ConstraintRange>(Constraints);
+}
+
//===----------------------------------------------------------------------===//
// Equality/diseqiality abstraction
//===----------------------------------------------------------------------===//
@@ -1373,6 +1384,182 @@
return {RangeFactory, ValueFactory.getValue(Min), ValueFactory.getValue(Max)};
}
+//===----------------------------------------------------------------------===//
+// Constraint assignment logic
+//===----------------------------------------------------------------------===//
+
+/// ConstraintAssignorBase is a small utility class that unifies visitor
+/// for ranges with a visitor for constraints (rangeset/range/constant).
+///
+/// It is designed to have one derived class, but generally it can have more.
+/// Derived class can control which types we handle by defining methods of the
+/// following form:
+///
+/// bool handle${SYMBOL}To${CONSTRAINT}(const SYMBOL *Sym,
+/// CONSTRAINT Constraint);
+///
+/// where SYMBOL is the type of the symbol (e.g. SymSymExpr, SymbolCast, etc.)
+/// CONSTRAINT is the type of constraint (RangeSet/Range/Const)
+/// return value signifies whether we should try other handle methods
+/// (i.e. false would mean to stop right after calling this method)
+template <class Derived> class ConstraintAssignorBase {
+public:
+ using Const = const llvm::APSInt &;
+
+#define DISPATCH(CLASS) return assign##CLASS##Impl(cast<CLASS>(Sym), Constraint)
+
+#define ASSIGN(CLASS, TO, SYM, CONSTRAINT) \
+ if (!static_cast<Derived *>(this)->assign##CLASS##To##TO(SYM, CONSTRAINT)) \
+ return false
+
+ void assign(SymbolRef Sym, RangeSet Constraint) {
+ assignImpl(Sym, Constraint);
+ }
+
+ bool assignImpl(SymbolRef Sym, RangeSet Constraint) {
+ switch (Sym->getKind()) {
+#define SYMBOL(Id, Parent) \
+ case SymExpr::Id##Kind: \
+ DISPATCH(Id);
+#include "clang/StaticAnalyzer/Core/PathSensitive/Symbols.def"
+ }
+ llvm_unreachable("Unknown SymExpr kind!");
+ }
+
+#define DEFAULT_ASSIGN(Id) \
+ bool assign##Id##To##RangeSet(const Id *Sym, RangeSet Constraint) { \
+ return true; \
+ } \
+ bool assign##Id##To##Range(const Id *Sym, Range Constraint) { return true; } \
+ bool assign##Id##To##Const(const Id *Sym, Const Constraint) { return true; }
+
+ // When we dispatch for constraint types, we first try to check
+ // if the new constraint is the constant and try the corresponding
+ // assignor methods. If it didn't interrupt, we can proceed to the
+ // range, and finally to the range set.
+#define CONSTRAINT_DISPATCH(Id) \
+ if (const llvm::APSInt *Const = Constraint.getConcreteValue()) { \
+ ASSIGN(Id, Const, Sym, *Const); \
+ } \
+ if (Constraint.size() == 1) { \
+ ASSIGN(Id, Range, Sym, *Constraint.begin()); \
+ } \
+ ASSIGN(Id, RangeSet, Sym, Constraint)
+
+ // Our internal assign method first tries to call assignor methods for all
+ // constraint types that apply. And if not interrupted, continues with its
+ // parent class.
+#define SYMBOL(Id, Parent) \
+ bool assign##Id##Impl(const Id *Sym, RangeSet Constraint) { \
+ CONSTRAINT_DISPATCH(Id); \
+ DISPATCH(Parent); \
+ } \
+ DEFAULT_ASSIGN(Id)
+#define ABSTRACT_SYMBOL(Id, Parent) SYMBOL(Id, Parent)
+#include "clang/StaticAnalyzer/Core/PathSensitive/Symbols.def"
+
+ // Default implementations for the top class that doesn't have parents.
+ bool assignSymExprImpl(const SymExpr *Sym, RangeSet Constraint) {
+ CONSTRAINT_DISPATCH(SymExpr);
+ return true;
+ }
+ DEFAULT_ASSIGN(SymExpr);
+
+#undef DISPATCH
+#undef CONSTRAINT_DISPATCH
+#undef DEFAULT_ASSIGN
+#undef ASSIGN
+};
+
+/// A little component aggregating all of the reasoning we have about
+/// assigning new constraints to symbols.
+///
+/// The main purpose of this class is to associate constraints to symbols,
+/// and impose additional constraints on other symbols, when we can imply
+/// them.
+///
+/// It has a nice symmetry with SymbolicRangeInferrer. When the latter
+/// can provide more precise ranges by looking into the operands of the
+/// expression in question, ConstraintAssignor looks into the operands
+/// to see if we can imply more from the new constraint.
+class ConstraintAssignor : public ConstraintAssignorBase<ConstraintAssignor> {
+public:
+ template <class ClassOrSymbol>
+ LLVM_NODISCARD static ProgramStateRef
+ assign(ProgramStateRef State, SValBuilder &Builder, RangeSet::Factory &F,
+ ClassOrSymbol CoS, RangeSet NewConstraint) {
+ if (!State || NewConstraint.isEmpty())
+ return nullptr;
+
+ ConstraintAssignor Assignor{State, Builder, F};
+ return Assignor.assign(CoS, NewConstraint);
+ }
+
+ inline bool assignSymExprToConst(const SymExpr *Sym, Const Constraint);
+
+private:
+ ConstraintAssignor(ProgramStateRef State, SValBuilder &Builder,
+ RangeSet::Factory &F)
+ : State(State), Builder(Builder), RangeFactory(F) {}
+ using Base = ConstraintAssignorBase<ConstraintAssignor>;
+
+ /// Base method for handling new constraints for symbols.
+ LLVM_NODISCARD ProgramStateRef assign(SymbolRef Sym, RangeSet NewConstraint) {
+ // All constraints are actually associated with equivalence classes, and
+ // that's what we are going to do first.
+ State = assign(EquivalenceClass::find(State, Sym), NewConstraint);
+ if (!State)
+ return nullptr;
+
+ // And after that we can check what other things we can get from this
+ // constraint.
+ Base::assign(Sym, NewConstraint);
+ return State;
+ }
+
+ /// Base method for handling new constraints for classes.
+ LLVM_NODISCARD ProgramStateRef assign(EquivalenceClass Class,
+ RangeSet NewConstraint) {
+ // There is a chance that we might need to update constraints for the
+ // classes that are known to be disequal to Class.
+ //
+ // In order for this to be even possible, the new constraint should
+ // be simply a constant because we can't reason about range disequalities.
+ if (const llvm::APSInt *Point = NewConstraint.getConcreteValue()) {
+
+ ConstraintRangeTy Constraints = State->get<ConstraintRange>();
+ ConstraintRangeTy::Factory &CF = State->get_context<ConstraintRange>();
+
+ // Add new constraint.
+ Constraints = CF.add(Constraints, Class, NewConstraint);
+
+ for (EquivalenceClass DisequalClass : Class.getDisequalClasses(State)) {
+ RangeSet UpdatedConstraint = SymbolicRangeInferrer::inferRange(
+ RangeFactory, State, DisequalClass);
+
+ UpdatedConstraint = RangeFactory.deletePoint(UpdatedConstraint, *Point);
+
+ // If we end up with at least one of the disequal classes to be
+ // constrained with an empty range-set, the state is infeasible.
+ if (UpdatedConstraint.isEmpty())
+ return nullptr;
+
+ Constraints = CF.add(Constraints, DisequalClass, UpdatedConstraint);
+ }
+ assert(areFeasible(Constraints) && "Constraint manager shouldn't produce "
+ "a state with infeasible constraints");
+
+ return setConstraints(State, Constraints);
+ }
+
+ return setConstraint(State, Class, NewConstraint);
+ }
+
+ ProgramStateRef State;
+ SValBuilder &Builder;
+ RangeSet::Factory &RangeFactory;
+};
+
//===----------------------------------------------------------------------===//
// Constraint manager implementation details
//===----------------------------------------------------------------------===//
@@ -1449,6 +1636,10 @@
RangeSet getRange(ProgramStateRef State, SymbolRef Sym);
RangeSet getRange(ProgramStateRef State, EquivalenceClass Class);
+ ProgramStateRef setRange(ProgramStateRef State, SymbolRef Sym,
+ RangeSet Range);
+ ProgramStateRef setRange(ProgramStateRef State, EquivalenceClass Class,
+ RangeSet Range);
RangeSet getSymLTRange(ProgramStateRef St, SymbolRef Sym,
const llvm::APSInt &Int,
@@ -1490,7 +1681,7 @@
// This is an infeasible assumption.
return nullptr;
- if (ProgramStateRef NewState = setConstraint(State, Sym, NewConstraint)) {
+ if (ProgramStateRef NewState = setRange(State, Sym, NewConstraint)) {
if (auto Equality = EqualityInfo::extract(Sym, Int, Adjustment)) {
// If the original assumption is not Sym + Adjustment !=/</> Int,
// we should invert IsEquality flag.
@@ -1520,85 +1711,36 @@
SymbolRef RHS) {
return EquivalenceClass::merge(F, State, LHS, RHS);
}
+};
- LLVM_NODISCARD ProgramStateRef setConstraint(ProgramStateRef State,
- EquivalenceClass Class,
- RangeSet Constraint) {
- ConstraintRangeTy Constraints = State->get<ConstraintRange>();
- ConstraintRangeTy::Factory &CF = State->get_context<ConstraintRange>();
-
- assert(!Constraint.isEmpty() && "New constraint should not be empty");
-
- // Add new constraint.
- Constraints = CF.add(Constraints, Class, Constraint);
-
- // There is a chance that we might need to update constraints for the
- // classes that are known to be disequal to Class.
- //
- // In order for this to be even possible, the new constraint should
- // be simply a constant because we can't reason about range disequalities.
- if (const llvm::APSInt *Point = Constraint.getConcreteValue())
- for (EquivalenceClass DisequalClass : Class.getDisequalClasses(State)) {
- RangeSet UpdatedConstraint = getRange(State, DisequalClass);
- UpdatedConstraint = F.deletePoint(UpdatedConstraint, *Point);
-
- // If we end up with at least one of the disequal classes to be
- // constrained with an empty range-set, the state is infeasible.
- if (UpdatedConstraint.isEmpty())
- return nullptr;
-
- Constraints = CF.add(Constraints, DisequalClass, UpdatedConstraint);
- }
-
- assert(areFeasible(Constraints) && "Constraint manager shouldn't produce "
- "a state with infeasible constraints");
-
- return State->set<ConstraintRange>(Constraints);
+bool ConstraintAssignor::assignSymExprToConst(const SymExpr *Sym,
+ const llvm::APSInt &Constraint) {
+ llvm::SmallSet<EquivalenceClass, 4> SimplifiedClasses;
+ // Iterate over all equivalence classes and try to simplify them.
+ ClassMembersTy Members = State->get<ClassMembers>();
+ for (std::pair<EquivalenceClass, SymbolSet> ClassToSymbolSet : Members) {
+ EquivalenceClass Class = ClassToSymbolSet.first;
+ State = Class.simplify(Builder, RangeFactory, State);
+ if (!State)
+ return false;
+ SimplifiedClasses.insert(Class);
}
- // Associate a constraint to a symbolic expression. First, we set the
- // constraint in the State, then we try to simplify existing symbolic
- // expressions based on the newly set constraint.
- LLVM_NODISCARD inline ProgramStateRef
- setConstraint(ProgramStateRef State, SymbolRef Sym, RangeSet Constraint) {
- assert(State);
-
- State = setConstraint(State, EquivalenceClass::find(State, Sym), Constraint);
+ // Trivial equivalence classes (those that have only one symbol member) are
+ // not stored in the State. Thus, we must skim through the constraints as
+ // well. And we try to simplify symbols in the constraints.
+ ConstraintRangeTy Constraints = State->get<ConstraintRange>();
+ for (std::pair<EquivalenceClass, RangeSet> ClassConstraint : Constraints) {
+ EquivalenceClass Class = ClassConstraint.first;
+ if (SimplifiedClasses.count(Class)) // Already simplified.
+ continue;
+ State = Class.simplify(Builder, RangeFactory, State);
if (!State)
- return nullptr;
-
- // We have a chance to simplify existing symbolic values if the new
- // constraint is a constant.
- if (!Constraint.getConcreteValue())
- return State;
-
- llvm::SmallSet<EquivalenceClass, 4> SimplifiedClasses;
- // Iterate over all equivalence classes and try to simplify them.
- ClassMembersTy Members = State->get<ClassMembers>();
- for (std::pair<EquivalenceClass, SymbolSet> ClassToSymbolSet : Members) {
- EquivalenceClass Class = ClassToSymbolSet.first;
- State = Class.simplify(getSValBuilder(), F, State);
- if (!State)
- return nullptr;
- SimplifiedClasses.insert(Class);
- }
-
- // Trivial equivalence classes (those that have only one symbol member) are
- // not stored in the State. Thus, we must skim through the constraints as
- // well. And we try to simplify symbols in the constraints.
- ConstraintRangeTy Constraints = State->get<ConstraintRange>();
- for (std::pair<EquivalenceClass, RangeSet> ClassConstraint : Constraints) {
- EquivalenceClass Class = ClassConstraint.first;
- if (SimplifiedClasses.count(Class)) // Already simplified.
- continue;
- State = Class.simplify(getSValBuilder(), F, State);
- if (!State)
- return nullptr;
- }
-
- return State;
+ return false;
}
-};
+
+ return true;
+}
} // end anonymous namespace
@@ -2244,6 +2386,18 @@
return SymbolicRangeInferrer::inferRange(F, State, Class);
}
+ProgramStateRef RangeConstraintManager::setRange(ProgramStateRef State,
+ SymbolRef Sym,
+ RangeSet Range) {
+ return ConstraintAssignor::assign(State, getSValBuilder(), F, Sym, Range);
+}
+
+ProgramStateRef RangeConstraintManager::setRange(ProgramStateRef State,
+ EquivalenceClass Class,
+ RangeSet Range) {
+ return ConstraintAssignor::assign(State, getSValBuilder(), F, Class, Range);
+}
+
//===------------------------------------------------------------------------===
// assumeSymX methods: protected interface for RangeConstraintManager.
//===------------------------------------------------------------------------===/
@@ -2397,7 +2551,7 @@
const llvm::APSInt &Int,
const llvm::APSInt &Adjustment) {
RangeSet New = getSymGERange(St, Sym, Int, Adjustment);
- return New.isEmpty() ? nullptr : setConstraint(St, Sym, New);
+ return setRange(St, Sym, New);
}
RangeSet
@@ -2441,7 +2595,7 @@
const llvm::APSInt &Int,
const llvm::APSInt &Adjustment) {
RangeSet New = getSymLERange(St, Sym, Int, Adjustment);
- return New.isEmpty() ? nullptr : setConstraint(St, Sym, New);
+ return setRange(St, Sym, New);
}
ProgramStateRef RangeConstraintManager::assumeSymWithinInclusiveRange(
@@ -2451,7 +2605,7 @@
if (New.isEmpty())
return nullptr;
RangeSet Out = getSymLERange([&] { return New; }, To, Adjustment);
- return Out.isEmpty() ? nullptr : setConstraint(State, Sym, Out);
+ return setRange(State, Sym, Out);
}
ProgramStateRef RangeConstraintManager::assumeSymOutsideInclusiveRange(
@@ -2460,7 +2614,7 @@
RangeSet RangeLT = getSymLTRange(State, Sym, From, Adjustment);
RangeSet RangeGT = getSymGTRange(State, Sym, To, Adjustment);
RangeSet New(F.add(RangeLT, RangeGT));
- return New.isEmpty() ? nullptr : setConstraint(State, Sym, New);
+ return setRange(State, Sym, New);
}
//===----------------------------------------------------------------------===//
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