[analyzer] a few helper methods for getting and comparing symbolic values

[george.karpenkov]

Summary

API calls should express intent, and that's a motivation behind this patch.

[NoQ]

include/clang/StaticAnalyzer/Core/PathSensitive/ConstraintManager.h

43

llvm::Optional::getValue() already checks for this.
Also you can use *Val.

include/clang/StaticAnalyzer/Core/PathSensitive/ConstraintManager.h

 public:
   /// Construct a ConditionTruthVal indicating the constraint is constrained
   /// to either true or false, depending on the boolean value provided.
   ConditionTruthVal(bool constraint) : Val(constraint) {}
 
   /// Construct a ConstraintVal indicating the constraint is underconstrained.
   ConditionTruthVal() {}
 
+  /// \return Stored value, assuming that the value is known.
+  /// Crashes otherwise.
+  bool getValue() const {
+    assert(Val.hasValue());
+    return Val.getValue();
+  }
+
   /// Return true if the constraint is perfectly constrained to 'true'.
   bool isConstrainedTrue() const {
     return Val.hasValue() && Val.getValue();
   }
 
   /// Return true if the constraint is perfectly constrained to 'false'.
   bool isConstrainedFalse() const {
     return Val.hasValue() && !Val.getValue();

include/clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h

public:
   /// corresponding states (respectively).
   ///
   /// This is more efficient than calling assume() twice. Note that one (but not
   /// both) of the returned states may be NULL.
   std::pair<ProgramStateRef, ProgramStateRef>
   assumeInclusiveRange(DefinedOrUnknownSVal Val, const llvm::APSInt &From,
                        const llvm::APSInt &To) const;
 
+  /// \brief Check if the given SVal is not constrained to zero and is not
+  ///        a zero constant.
+  ConditionTruthVal isNonNull(SVal V) const;
+
   /// \brief Check if the given SVal is constrained to zero or is a zero
   ///        constant.
   ConditionTruthVal isNull(SVal V) const;
 
+  /// \return Whether values \p Lhs and \p Rhs are equal.
+  ConditionTruthVal areEqual(SVal Lhs, SVal Rhs) const;
+
   /// Utility method for getting regions.
   const VarRegion* getRegion(const VarDecl *D, const LocationContext *LC) const;
 
   //==---------------------------------------------------------------------==//
   // Binding and retrieving values to/from the environment and symbolic store.
   //==---------------------------------------------------------------------==//
 
   /// Create a new state by binding the value 'V' to the statement 'S' in the

include/clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h

 #include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
 
 namespace clang {
 
 class CXXBoolLiteralExpr;
 
 namespace ento {
 
+class ConditionTruthVal;
+
 class SValBuilder {
   virtual void anchor();
 protected:
   ASTContext &Context;
   
   /// Manager of APSInt values.
   BasicValueFactory BasicVals;
 
public:
   virtual SVal simplifySVal(ProgramStateRef State, SVal Val) = 0;
   
   /// Constructs a symbolic expression for two non-location values.
   SVal makeSymExprValNN(ProgramStateRef state, BinaryOperator::Opcode op,
                       NonLoc lhs, NonLoc rhs, QualType resultTy);
 
   SVal evalBinOp(ProgramStateRef state, BinaryOperator::Opcode op,
                  SVal lhs, SVal rhs, QualType type);
-  
+  /// \return Whether values in \p lhs and \p rhs are equal at \p state.
+  ConditionTruthVal areEqual(ProgramStateRef state, SVal lhs, SVal rhs);
+
+  SVal evalEQ(ProgramStateRef state, SVal lhs, SVal rhs);
+
   DefinedOrUnknownSVal evalEQ(ProgramStateRef state, DefinedOrUnknownSVal lhs,
                               DefinedOrUnknownSVal rhs);
 
   ASTContext &getContext() { return Context; }
   const ASTContext &getContext() const { return Context; }
 
   ProgramStateManager &getStateManager() { return StateMgr; }
   

lib/StaticAnalyzer/Core/ProgramState.cpp

ProgramStateRef ProgramState::assumeInBound(DefinedOrUnknownSVal Idx,
   if (inBound.isUnknownOrUndef())
     return this;
 
   // Finally, let the constraint manager take care of it.
   ConstraintManager &CM = SM.getConstraintManager();
   return CM.assume(this, inBound.castAs<DefinedSVal>(), Assumption);
 }
 
+ConditionTruthVal ProgramState::isNonNull(SVal V) const {
+  ConditionTruthVal IsNull = isNull(V);
+  if (IsNull.isUnderconstrained())
+    return IsNull;
+  return ConditionTruthVal(!IsNull.getValue());
+}
+
+ConditionTruthVal ProgramState::areEqual(SVal Lhs, SVal Rhs) const {
+  return stateMgr->getSValBuilder().areEqual(this, Lhs, Rhs);
+}
+
 ConditionTruthVal ProgramState::isNull(SVal V) const {
   if (V.isZeroConstant())
     return true;
 
   if (V.isConstant())
     return false;
 
   SymbolRef Sym = V.getAsSymbol(/* IncludeBaseRegion */ true);

lib/StaticAnalyzer/Core/SValBuilder.cpp

if (Optional<Loc> RV = rhs.getAs<Loc>()) {
     // Commute the operands.
     return evalBinOpLN(state, op, *RV, lhs.castAs<NonLoc>(), type);
   }
 
   return evalBinOpNN(state, op, lhs.castAs<NonLoc>(), rhs.castAs<NonLoc>(),
                      type);
 }
 
+ConditionTruthVal SValBuilder::areEqual(ProgramStateRef state, SVal lhs,
+                                        SVal rhs) {
+  return state->isNonNull(evalEQ(state, lhs, rhs));
+}
+
+SVal SValBuilder::evalEQ(ProgramStateRef state, SVal lhs, SVal rhs) {
+  return evalBinOp(state, BO_EQ, lhs, rhs, getConditionType());
+}
+
 DefinedOrUnknownSVal SValBuilder::evalEQ(ProgramStateRef state,
                                          DefinedOrUnknownSVal lhs,
                                          DefinedOrUnknownSVal rhs) {
-  return evalBinOp(state, BO_EQ, lhs, rhs, getConditionType())
+  return evalEQ(state, static_cast<SVal>(lhs), static_cast<SVal>(rhs))
       .castAs<DefinedOrUnknownSVal>();
 }
 
 /// Recursively check if the pointer types are equal modulo const, volatile,
 /// and restrict qualifiers. Also, assume that all types are similar to 'void'.
 /// Assumes the input types are canonical.
 static bool shouldBeModeledWithNoOp(ASTContext &Context, QualType ToTy,
                                                          QualType FromTy) {