[analyzer] Move canReasonAbout from Z3ConstraintManager to SMTConstraintManager

Summary:
This patch moves the last method in `Z3ConstraintManager` to `SMTConstraintManager`: `canReasonAbout()`.

The `canReasonAbout()` method checks if a given `SVal` can be encoded in SMT. I've added a new method to the SMT API to return true if a solver can encode floating-point arithmetics and it was enough to make `canReasonAbout()` solver independent.

As an annoying side-effect, `Z3ConstraintManager` is pretty empty now and only (1) creates the Z3 solver object by calling `CreateZ3Solver()` and (2) instantiates `SMTConstraintManager`. Maybe we can get rid of this class altogether in the future: a `CreateSMTConstraintManager()` method that does (1) and (2) and returns the constraint manager object?

Reviewers: george.karpenkov, NoQ

Reviewed By: george.karpenkov

Subscribers: mehdi_amini, xazax.hun, szepet, a.sidorin, dexonsmith, Szelethus, donat.nagy, dkrupp

Differential Revision: https://reviews.llvm.org/D53694

llvm-svn: 345284

3 files changed, 51 insertions, 43 deletions

diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SMTConstraintManager.h b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SMTConstraintManager.h
index db05bdaa4d6..54cf3c39dd2 100644
--- a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SMTConstraintManager.h
+++ b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SMTConstraintManager.h
@@ -218,6 +218,52 @@ public:
     OS << nl;
   }
 
+  bool canReasonAbout(SVal X) const override {
+    const TargetInfo &TI = getBasicVals().getContext().getTargetInfo();
+
+    Optional<nonloc::SymbolVal> SymVal = X.getAs<nonloc::SymbolVal>();
+    if (!SymVal)
+      return true;
+
+    const SymExpr *Sym = SymVal->getSymbol();
+    QualType Ty = Sym->getType();
+
+    // Complex types are not modeled
+    if (Ty->isComplexType() || Ty->isComplexIntegerType())
+      return false;
+
+    // Non-IEEE 754 floating-point types are not modeled
+    if ((Ty->isSpecificBuiltinType(BuiltinType::LongDouble) &&
+         (&TI.getLongDoubleFormat() == &llvm::APFloat::x87DoubleExtended() ||
+          &TI.getLongDoubleFormat() == &llvm::APFloat::PPCDoubleDouble())))
+      return false;
+
+    if (Ty->isRealFloatingType())
+      return Solver->isFPSupported();
+
+    if (isa<SymbolData>(Sym))
+      return true;
+
+    SValBuilder &SVB = getSValBuilder();
+
+    if (const SymbolCast *SC = dyn_cast<SymbolCast>(Sym))
+      return canReasonAbout(SVB.makeSymbolVal(SC->getOperand()));
+
+    if (const BinarySymExpr *BSE = dyn_cast<BinarySymExpr>(Sym)) {
+      if (const SymIntExpr *SIE = dyn_cast<SymIntExpr>(BSE))
+        return canReasonAbout(SVB.makeSymbolVal(SIE->getLHS()));
+
+      if (const IntSymExpr *ISE = dyn_cast<IntSymExpr>(BSE))
+        return canReasonAbout(SVB.makeSymbolVal(ISE->getRHS()));
+
+      if (const SymSymExpr *SSE = dyn_cast<SymSymExpr>(BSE))
+        return canReasonAbout(SVB.makeSymbolVal(SSE->getLHS())) &&
+               canReasonAbout(SVB.makeSymbolVal(SSE->getRHS()));
+    }
+
+    llvm_unreachable("Unsupported expression to reason about!");
+  }
+
   /// Dumps SMT formula
   LLVM_DUMP_METHOD void dump() const { Solver->dump(); }
 
diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SMTSolver.h b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SMTSolver.h
index 0db1e364b6e..2abe5fc9874 100644
--- a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SMTSolver.h
+++ b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SMTSolver.h
@@ -285,6 +285,9 @@ public:
   /// Reset the solver and remove all constraints.
   virtual void reset() = 0;
 
+  /// Checks if the solver supports floating-points.
+  virtual bool isFPSupported() = 0;
+
   virtual void print(raw_ostream &OS) const = 0;
 };
 
diff --git a/clang/lib/StaticAnalyzer/Core/Z3ConstraintManager.cpp b/clang/lib/StaticAnalyzer/Core/Z3ConstraintManager.cpp
index e6a5f11fa14..028010726a8 100644
--- a/clang/lib/StaticAnalyzer/Core/Z3ConstraintManager.cpp
+++ b/clang/lib/StaticAnalyzer/Core/Z3ConstraintManager.cpp
@@ -860,6 +860,8 @@ public:
     return Z3Model(Context, Z3_solver_get_model(Context.Context, Solver));
   }
 
+  bool isFPSupported() override { return true; }
+
   /// Reset the solver and remove all constraints.
   void reset() override { Z3_solver_reset(Context.Context, Solver); }
 
@@ -874,49 +876,6 @@ class Z3ConstraintManager : public SMTConstraintManager<ConstraintZ3, Z3Expr> {
 public:
   Z3ConstraintManager(SubEngine *SE, SValBuilder &SB)
       : SMTConstraintManager(SE, SB, Solver) {}
-
-  bool canReasonAbout(SVal X) const override {
-    const TargetInfo &TI = getBasicVals().getContext().getTargetInfo();
-
-    Optional<nonloc::SymbolVal> SymVal = X.getAs<nonloc::SymbolVal>();
-    if (!SymVal)
-      return true;
-
-    const SymExpr *Sym = SymVal->getSymbol();
-    QualType Ty = Sym->getType();
-
-    // Complex types are not modeled
-    if (Ty->isComplexType() || Ty->isComplexIntegerType())
-      return false;
-
-    // Non-IEEE 754 floating-point types are not modeled
-    if ((Ty->isSpecificBuiltinType(BuiltinType::LongDouble) &&
-         (&TI.getLongDoubleFormat() == &llvm::APFloat::x87DoubleExtended() ||
-          &TI.getLongDoubleFormat() == &llvm::APFloat::PPCDoubleDouble())))
-      return false;
-
-    if (isa<SymbolData>(Sym))
-      return true;
-
-    SValBuilder &SVB = getSValBuilder();
-
-    if (const SymbolCast *SC = dyn_cast<SymbolCast>(Sym))
-      return canReasonAbout(SVB.makeSymbolVal(SC->getOperand()));
-
-    if (const BinarySymExpr *BSE = dyn_cast<BinarySymExpr>(Sym)) {
-      if (const SymIntExpr *SIE = dyn_cast<SymIntExpr>(BSE))
-        return canReasonAbout(SVB.makeSymbolVal(SIE->getLHS()));
-
-      if (const IntSymExpr *ISE = dyn_cast<IntSymExpr>(BSE))
-        return canReasonAbout(SVB.makeSymbolVal(ISE->getRHS()));
-
-      if (const SymSymExpr *SSE = dyn_cast<SymSymExpr>(BSE))
-        return canReasonAbout(SVB.makeSymbolVal(SSE->getLHS())) &&
-               canReasonAbout(SVB.makeSymbolVal(SSE->getRHS()));
-    }
-
-    llvm_unreachable("Unsupported expression to reason about!");
-  }
 }; // end class Z3ConstraintManager
 
 } // end anonymous namespace