Refactor Assume logic into a separate class ConstraintManager.

llvm-svn: 55412

clang/lib/Analysis/BasicConstraintManager.cpp

@@ -0,0 +1,298 @@
+#include "clang/Analysis/PathSensitive/ConstraintManager.h"
+#include "clang/Analysis/PathSensitive/GRState.h"
+#include "llvm/Support/Compiler.h"
+
+using namespace clang;
+
+namespace {
+
+// BasicConstraintManager only tracks equality and inequality constraints of
+// constants and integer variables.
+class VISIBILITY_HIDDEN BasicConstraintManager : public ConstraintManager {
+  typedef llvm::ImmutableMap<SymbolID, GRState::IntSetTy> ConstNotEqTy;
+  typedef llvm::ImmutableMap<SymbolID, const llvm::APSInt*> ConstEqTy;
+
+  GRStateManager& StateMgr;
+
+public:
+  BasicConstraintManager(GRStateManager& statemgr) : StateMgr(statemgr) {}
+
+  virtual const GRState* Assume(const GRState* St, RVal Cond,
+                                bool Assumption, bool& isFeasible);
+
+  const GRState* Assume(const GRState* St, LVal Cond, bool Assumption,
+                        bool& isFeasible);
+
+  const GRState* AssumeAux(const GRState* St, LVal Cond,bool Assumption,
+                           bool& isFeasible);
+
+  const GRState* Assume(const GRState* St, NonLVal Cond, bool Assumption,
+                        bool& isFeasible);
+
+  const GRState* AssumeAux(const GRState* St, NonLVal Cond, bool Assumption,
+                           bool& isFeasible);
+
+  const GRState* AssumeSymInt(const GRState* St, bool Assumption,
+                              const SymIntConstraint& C, bool& isFeasible);
+
+  const GRState* AssumeSymNE(const GRState* St, SymbolID sym,
+                                const llvm::APSInt& V, bool& isFeasible);
+
+  const GRState* AssumeSymEQ(const GRState* St, SymbolID sym,
+                                const llvm::APSInt& V, bool& isFeasible);
+
+  const GRState* AssumeSymLT(const GRState* St, SymbolID sym,
+                                    const llvm::APSInt& V, bool& isFeasible);
+
+  const GRState* AssumeSymGT(const GRState* St, SymbolID sym,
+                             const llvm::APSInt& V, bool& isFeasible);
+
+  const GRState* AssumeSymGE(const GRState* St, SymbolID sym,
+                             const llvm::APSInt& V, bool& isFeasible);
+
+  const GRState* AssumeSymLE(const GRState* St, SymbolID sym,
+                             const llvm::APSInt& V, bool& isFeasible);
+  };
+
+} // end anonymous namespace
+
+ConstraintManager* clang::CreateBasicConstraintManager(GRStateManager& StateMgr)
+{
+  return new BasicConstraintManager(StateMgr);
+}
+
+const GRState* BasicConstraintManager::Assume(const GRState* St, RVal Cond,
+                                            bool Assumption, bool& isFeasible) {
+  if (Cond.isUnknown()) {
+    isFeasible = true;
+    return St;
+  }
+
+  if (isa<NonLVal>(Cond))
+    return Assume(St, cast<NonLVal>(Cond), Assumption, isFeasible);
+  else
+    return Assume(St, cast<LVal>(Cond), Assumption, isFeasible);
+}
+
+const GRState* BasicConstraintManager::Assume(const GRState* St, LVal Cond,
+                                            bool Assumption, bool& isFeasible) {
+  St = AssumeAux(St, Cond, Assumption, isFeasible);
+  // TF->EvalAssume(*this, St, Cond, Assumption, isFeasible)
+  return St;
+}
+
+const GRState* BasicConstraintManager::AssumeAux(const GRState* St, LVal Cond,
+                                            bool Assumption, bool& isFeasible) {
+  BasicValueFactory& BasicVals = StateMgr.getBasicVals();
+
+  switch (Cond.getSubKind()) {
+  default:
+    assert (false && "'Assume' not implemented for this LVal.");
+    return St;
+
+  case lval::SymbolValKind:
+    if (Assumption)
+      return AssumeSymNE(St, cast<lval::SymbolVal>(Cond).getSymbol(),
+                         BasicVals.getZeroWithPtrWidth(), isFeasible);
+    else
+      return AssumeSymEQ(St, cast<lval::SymbolVal>(Cond).getSymbol(),
+                         BasicVals.getZeroWithPtrWidth(), isFeasible);
+
+  case lval::DeclValKind:
+  case lval::FuncValKind:
+  case lval::GotoLabelKind:
+  case lval::StringLiteralValKind:
+    isFeasible = Assumption;
+    return St;
+
+  case lval::FieldOffsetKind:
+    return AssumeAux(St, cast<lval::FieldOffset>(Cond).getBase(),
+                     Assumption, isFeasible);
+
+  case lval::ArrayOffsetKind:
+    return AssumeAux(St, cast<lval::ArrayOffset>(Cond).getBase(),
+                     Assumption, isFeasible);
+
+  case lval::ConcreteIntKind: {
+    bool b = cast<lval::ConcreteInt>(Cond).getValue() != 0;
+    isFeasible = b ? Assumption : !Assumption;
+    return St;
+  }
+  } // end switch
+}
+
+const GRState*
+BasicConstraintManager::Assume(const GRState* St, NonLVal Cond, bool Assumption,
+                               bool& isFeasible) {
+  St = AssumeAux(St, Cond, Assumption, isFeasible);
+  // TF->EvalAssume() does nothing now.
+  return St;
+}
+
+const GRState*
+BasicConstraintManager::AssumeAux(const GRState* St,NonLVal Cond,
+                                  bool Assumption, bool& isFeasible) {
+  BasicValueFactory& BasicVals = StateMgr.getBasicVals();
+  SymbolManager& SymMgr = StateMgr.getSymbolManager();
+
+  switch (Cond.getSubKind()) {
+  default:
+    assert(false && "'Assume' not implemented for this NonLVal");
+
+  case nonlval::SymbolValKind: {
+    nonlval::SymbolVal& SV = cast<nonlval::SymbolVal>(Cond);
+    SymbolID sym = SV.getSymbol();
+
+    if (Assumption)
+      return AssumeSymNE(St, sym, BasicVals.getValue(0, SymMgr.getType(sym)),
+                         isFeasible);
+    else
+      return AssumeSymEQ(St, sym, BasicVals.getValue(0, SymMgr.getType(sym)),
+                         isFeasible);
+  }
+
+  case nonlval::SymIntConstraintValKind:
+    return
+      AssumeSymInt(St, Assumption,
+                   cast<nonlval::SymIntConstraintVal>(Cond).getConstraint(),
+                   isFeasible);
+
+  case nonlval::ConcreteIntKind: {
+    bool b = cast<nonlval::ConcreteInt>(Cond).getValue() != 0;
+    isFeasible = b ? Assumption : !Assumption;
+    return St;
+  }
+
+  case nonlval::LValAsIntegerKind:
+    return AssumeAux(St, cast<nonlval::LValAsInteger>(Cond).getLVal(),
+                     Assumption, isFeasible);
+  } // end switch
+}
+
+const GRState*
+BasicConstraintManager::AssumeSymInt(const GRState* St, bool Assumption,
+                                  const SymIntConstraint& C, bool& isFeasible) {
+
+  switch (C.getOpcode()) {
+  default:
+    // No logic yet for other operators.
+    isFeasible = true;
+    return St;
+
+  case BinaryOperator::EQ:
+    if (Assumption)
+      return AssumeSymEQ(St, C.getSymbol(), C.getInt(), isFeasible);
+    else
+      return AssumeSymNE(St, C.getSymbol(), C.getInt(), isFeasible);
+
+  case BinaryOperator::NE:
+    if (Assumption)
+      return AssumeSymNE(St, C.getSymbol(), C.getInt(), isFeasible);
+    else
+      return AssumeSymEQ(St, C.getSymbol(), C.getInt(), isFeasible);
+
+  case BinaryOperator::GE:
+    if (Assumption)
+      return AssumeSymGE(St, C.getSymbol(), C.getInt(), isFeasible);
+    else
+      return AssumeSymLT(St, C.getSymbol(), C.getInt(), isFeasible);
+
+  case BinaryOperator::LE:
+    if (Assumption)
+      return AssumeSymLE(St, C.getSymbol(), C.getInt(), isFeasible);
+    else
+      return AssumeSymGT(St, C.getSymbol(), C.getInt(), isFeasible);
+  } // end switch
+}
+
+const GRState*
+BasicConstraintManager::AssumeSymNE(const GRState* St, SymbolID sym,
+                                    const llvm::APSInt& V, bool& isFeasible) {
+  // First, determine if sym == X, where X != V.
+  if (const llvm::APSInt* X = St->getSymVal(sym)) {
+    isFeasible = (*X != V);
+    return St;
+  }
+
+  // Second, determine if sym != V.
+  if (St->isNotEqual(sym, V)) {
+    isFeasible = true;
+    return St;
+  }
+
+  // If we reach here, sym is not a constant and we don't know if it is != V.
+  // Make that assumption.
+  isFeasible = true;
+  return StateMgr.AddNE(St, sym, V);
+}
+
+const GRState*
+BasicConstraintManager::AssumeSymEQ(const GRState* St, SymbolID sym,
+                                    const llvm::APSInt& V, bool& isFeasible) {
+  // First, determine if sym == X, where X != V.
+  if (const llvm::APSInt* X = St->getSymVal(sym)) {
+    isFeasible = *X == V;
+    return St;
+  }
+
+  // Second, determine if sym != V.
+  if (St->isNotEqual(sym, V)) {
+    isFeasible = false;
+    return St;
+  }
+
+  // If we reach here, sym is not a constant and we don't know if it is == V.
+  // Make that assumption.
+
+  isFeasible = true;
+  return StateMgr.AddEQ(St, sym, V);
+}
+
+// These logic will be handled in another ConstraintManager.
+const GRState*
+BasicConstraintManager::AssumeSymLT(const GRState* St, SymbolID sym,
+                                    const llvm::APSInt& V, bool& isFeasible) {
+
+  // FIXME: For now have assuming x < y be the same as assuming sym != V;
+  return AssumeSymNE(St, sym, V, isFeasible);
+}
+
+const GRState*
+BasicConstraintManager::AssumeSymGT(const GRState* St, SymbolID sym,
+                                    const llvm::APSInt& V, bool& isFeasible) {
+
+  // FIXME: For now have assuming x > y be the same as assuming sym != V;
+  return AssumeSymNE(St, sym, V, isFeasible);
+}
+
+const GRState*
+BasicConstraintManager::AssumeSymGE(const GRState* St, SymbolID sym,
+                                    const llvm::APSInt& V, bool& isFeasible) {
+
+  // FIXME: Primitive logic for now.  Only reject a path if the value of
+  //  sym is a constant X and !(X >= V).
+
+  if (const llvm::APSInt* X = St->getSymVal(sym)) {
+    isFeasible = *X >= V;
+    return St;
+  }
+
+  isFeasible = true;
+  return St;
+}
+
+const GRState*
+BasicConstraintManager::AssumeSymLE(const GRState* St, SymbolID sym,
+                                    const llvm::APSInt& V, bool& isFeasible) {
+
+  // FIXME: Primitive logic for now.  Only reject a path if the value of
+  //  sym is a constant X and !(X <= V).
+
+  if (const llvm::APSInt* X = St->getSymVal(sym)) {
+    isFeasible = *X <= V;
+    return St;
+  }
+
+  isFeasible = true;
+  return St;
+}