Add the clang library to the repo (with some of my changes, too).

1 files changed, 973 insertions, 0 deletions

diff --git a/clang/lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp b/clang/lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp
new file mode 100644
index 0000000..d0558f1
--- /dev/null
+++ b/clang/lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp
@@ -0,0 +1,973 @@
+// SimpleSValBuilder.cpp - A basic SValBuilder -----------------------*- C++ -*-
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines SimpleSValBuilder, a basic implementation of SValBuilder.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
+
+using namespace clang;
+using namespace ento;
+
+namespace {
+class SimpleSValBuilder : public SValBuilder {
+protected:
+  virtual SVal dispatchCast(SVal val, QualType castTy);
+  virtual SVal evalCastFromNonLoc(NonLoc val, QualType castTy);
+  virtual SVal evalCastFromLoc(Loc val, QualType castTy);
+
+public:
+  SimpleSValBuilder(llvm::BumpPtrAllocator &alloc, ASTContext &context,
+                    ProgramStateManager &stateMgr)
+                    : SValBuilder(alloc, context, stateMgr) {}
+  virtual ~SimpleSValBuilder() {}
+
+  virtual SVal evalMinus(NonLoc val);
+  virtual SVal evalComplement(NonLoc val);
+  virtual SVal evalBinOpNN(ProgramStateRef state, BinaryOperator::Opcode op,
+                           NonLoc lhs, NonLoc rhs, QualType resultTy);
+  virtual SVal evalBinOpLL(ProgramStateRef state, BinaryOperator::Opcode op,
+                           Loc lhs, Loc rhs, QualType resultTy);
+  virtual SVal evalBinOpLN(ProgramStateRef state, BinaryOperator::Opcode op,
+                           Loc lhs, NonLoc rhs, QualType resultTy);
+
+  /// getKnownValue - evaluates a given SVal. If the SVal has only one possible
+  ///  (integer) value, that value is returned. Otherwise, returns NULL.
+  virtual const llvm::APSInt *getKnownValue(ProgramStateRef state, SVal V);
+  
+  SVal MakeSymIntVal(const SymExpr *LHS, BinaryOperator::Opcode op,
+                     const llvm::APSInt &RHS, QualType resultTy);
+};
+} // end anonymous namespace
+
+SValBuilder *ento::createSimpleSValBuilder(llvm::BumpPtrAllocator &alloc,
+                                           ASTContext &context,
+                                           ProgramStateManager &stateMgr) {
+  return new SimpleSValBuilder(alloc, context, stateMgr);
+}
+
+//===----------------------------------------------------------------------===//
+// Transfer function for Casts.
+//===----------------------------------------------------------------------===//
+
+SVal SimpleSValBuilder::dispatchCast(SVal Val, QualType CastTy) {
+  assert(isa<Loc>(&Val) || isa<NonLoc>(&Val));
+  return isa<Loc>(Val) ? evalCastFromLoc(cast<Loc>(Val), CastTy)
+                       : evalCastFromNonLoc(cast<NonLoc>(Val), CastTy);
+}
+
+SVal SimpleSValBuilder::evalCastFromNonLoc(NonLoc val, QualType castTy) {
+
+  bool isLocType = Loc::isLocType(castTy);
+
+  if (nonloc::LocAsInteger *LI = dyn_cast<nonloc::LocAsInteger>(&val)) {
+    if (isLocType)
+      return LI->getLoc();
+
+    // FIXME: Correctly support promotions/truncations.
+    unsigned castSize = Context.getTypeSize(castTy);
+    if (castSize == LI->getNumBits())
+      return val;
+    return makeLocAsInteger(LI->getLoc(), castSize);
+  }
+
+  if (const SymExpr *se = val.getAsSymbolicExpression()) {
+    QualType T = Context.getCanonicalType(se->getType(Context));
+    // If types are the same or both are integers, ignore the cast.
+    // FIXME: Remove this hack when we support symbolic truncation/extension.
+    // HACK: If both castTy and T are integers, ignore the cast.  This is
+    // not a permanent solution.  Eventually we want to precisely handle
+    // extension/truncation of symbolic integers.  This prevents us from losing
+    // precision when we assign 'x = y' and 'y' is symbolic and x and y are
+    // different integer types.
+   if (haveSameType(T, castTy))
+      return val;
+
+    if (!isLocType)
+      return makeNonLoc(se, T, castTy);
+    return UnknownVal();
+  }
+
+  // If value is a non integer constant, produce unknown.
+  if (!isa<nonloc::ConcreteInt>(val))
+    return UnknownVal();
+
+  // Only handle casts from integers to integers - if val is an integer constant
+  // being cast to a non integer type, produce unknown.
+  if (!isLocType && !castTy->isIntegerType())
+    return UnknownVal();
+
+  llvm::APSInt i = cast<nonloc::ConcreteInt>(val).getValue();
+  i.setIsUnsigned(castTy->isUnsignedIntegerOrEnumerationType() || 
+                  Loc::isLocType(castTy));
+  i = i.extOrTrunc(Context.getTypeSize(castTy));
+
+  if (isLocType)
+    return makeIntLocVal(i);
+  else
+    return makeIntVal(i);
+}
+
+SVal SimpleSValBuilder::evalCastFromLoc(Loc val, QualType castTy) {
+
+  // Casts from pointers -> pointers, just return the lval.
+  //
+  // Casts from pointers -> references, just return the lval.  These
+  //   can be introduced by the frontend for corner cases, e.g
+  //   casting from va_list* to __builtin_va_list&.
+  //
+  if (Loc::isLocType(castTy) || castTy->isReferenceType())
+    return val;
+
+  // FIXME: Handle transparent unions where a value can be "transparently"
+  //  lifted into a union type.
+  if (castTy->isUnionType())
+    return UnknownVal();
+
+  if (castTy->isIntegerType()) {
+    unsigned BitWidth = Context.getTypeSize(castTy);
+
+    if (!isa<loc::ConcreteInt>(val))
+      return makeLocAsInteger(val, BitWidth);
+
+    llvm::APSInt i = cast<loc::ConcreteInt>(val).getValue();
+    i.setIsUnsigned(castTy->isUnsignedIntegerOrEnumerationType() || 
+                    Loc::isLocType(castTy));
+    i = i.extOrTrunc(BitWidth);
+    return makeIntVal(i);
+  }
+
+  // All other cases: return 'UnknownVal'.  This includes casting pointers
+  // to floats, which is probably badness it itself, but this is a good
+  // intermediate solution until we do something better.
+  return UnknownVal();
+}
+
+//===----------------------------------------------------------------------===//
+// Transfer function for unary operators.
+//===----------------------------------------------------------------------===//
+
+SVal SimpleSValBuilder::evalMinus(NonLoc val) {
+  switch (val.getSubKind()) {
+  case nonloc::ConcreteIntKind:
+    return cast<nonloc::ConcreteInt>(val).evalMinus(*this);
+  default:
+    return UnknownVal();
+  }
+}
+
+SVal SimpleSValBuilder::evalComplement(NonLoc X) {
+  switch (X.getSubKind()) {
+  case nonloc::ConcreteIntKind:
+    return cast<nonloc::ConcreteInt>(X).evalComplement(*this);
+  default:
+    return UnknownVal();
+  }
+}
+
+//===----------------------------------------------------------------------===//
+// Transfer function for binary operators.
+//===----------------------------------------------------------------------===//
+
+static BinaryOperator::Opcode NegateComparison(BinaryOperator::Opcode op) {
+  switch (op) {
+  default:
+    llvm_unreachable("Invalid opcode.");
+  case BO_LT: return BO_GE;
+  case BO_GT: return BO_LE;
+  case BO_LE: return BO_GT;
+  case BO_GE: return BO_LT;
+  case BO_EQ: return BO_NE;
+  case BO_NE: return BO_EQ;
+  }
+}
+
+static BinaryOperator::Opcode ReverseComparison(BinaryOperator::Opcode op) {
+  switch (op) {
+  default:
+    llvm_unreachable("Invalid opcode.");
+  case BO_LT: return BO_GT;
+  case BO_GT: return BO_LT;
+  case BO_LE: return BO_GE;
+  case BO_GE: return BO_LE;
+  case BO_EQ:
+  case BO_NE:
+    return op;
+  }
+}
+
+SVal SimpleSValBuilder::MakeSymIntVal(const SymExpr *LHS,
+                                    BinaryOperator::Opcode op,
+                                    const llvm::APSInt &RHS,
+                                    QualType resultTy) {
+  bool isIdempotent = false;
+
+  // Check for a few special cases with known reductions first.
+  switch (op) {
+  default:
+    // We can't reduce this case; just treat it normally.
+    break;
+  case BO_Mul:
+    // a*0 and a*1
+    if (RHS == 0)
+      return makeIntVal(0, resultTy);
+    else if (RHS == 1)
+      isIdempotent = true;
+    break;
+  case BO_Div:
+    // a/0 and a/1
+    if (RHS == 0)
+      // This is also handled elsewhere.
+      return UndefinedVal();
+    else if (RHS == 1)
+      isIdempotent = true;
+    break;
+  case BO_Rem:
+    // a%0 and a%1
+    if (RHS == 0)
+      // This is also handled elsewhere.
+      return UndefinedVal();
+    else if (RHS == 1)
+      return makeIntVal(0, resultTy);
+    break;
+  case BO_Add:
+  case BO_Sub:
+  case BO_Shl:
+  case BO_Shr:
+  case BO_Xor:
+    // a+0, a-0, a<<0, a>>0, a^0
+    if (RHS == 0)
+      isIdempotent = true;
+    break;
+  case BO_And:
+    // a&0 and a&(~0)
+    if (RHS == 0)
+      return makeIntVal(0, resultTy);
+    else if (RHS.isAllOnesValue())
+      isIdempotent = true;
+    break;
+  case BO_Or:
+    // a|0 and a|(~0)
+    if (RHS == 0)
+      isIdempotent = true;
+    else if (RHS.isAllOnesValue()) {
+      const llvm::APSInt &Result = BasicVals.Convert(resultTy, RHS);
+      return nonloc::ConcreteInt(Result);
+    }
+    break;
+  }
+
+  // Idempotent ops (like a*1) can still change the type of an expression.
+  // Wrap the LHS up in a NonLoc again and let evalCastFromNonLoc do the
+  // dirty work.
+  if (isIdempotent)
+      return evalCastFromNonLoc(nonloc::SymbolVal(LHS), resultTy);
+
+  // If we reach this point, the expression cannot be simplified.
+  // Make a SymbolVal for the entire expression.
+  return makeNonLoc(LHS, op, RHS, resultTy);
+}
+
+SVal SimpleSValBuilder::evalBinOpNN(ProgramStateRef state,
+                                  BinaryOperator::Opcode op,
+                                  NonLoc lhs, NonLoc rhs,
+                                  QualType resultTy)  {
+  // Handle trivial case where left-side and right-side are the same.
+  if (lhs == rhs)
+    switch (op) {
+      default:
+        break;
+      case BO_EQ:
+      case BO_LE:
+      case BO_GE:
+        return makeTruthVal(true, resultTy);
+      case BO_LT:
+      case BO_GT:
+      case BO_NE:
+        return makeTruthVal(false, resultTy);
+      case BO_Xor:
+      case BO_Sub:
+        return makeIntVal(0, resultTy);
+      case BO_Or:
+      case BO_And:
+        return evalCastFromNonLoc(lhs, resultTy);
+    }
+
+  while (1) {
+    switch (lhs.getSubKind()) {
+    default:
+      return makeGenericVal(state, op, lhs, rhs, resultTy);
+    case nonloc::LocAsIntegerKind: {
+      Loc lhsL = cast<nonloc::LocAsInteger>(lhs).getLoc();
+      switch (rhs.getSubKind()) {
+        case nonloc::LocAsIntegerKind:
+          return evalBinOpLL(state, op, lhsL,
+                             cast<nonloc::LocAsInteger>(rhs).getLoc(),
+                             resultTy);
+        case nonloc::ConcreteIntKind: {
+          // Transform the integer into a location and compare.
+          llvm::APSInt i = cast<nonloc::ConcreteInt>(rhs).getValue();
+          i.setIsUnsigned(true);
+          i = i.extOrTrunc(Context.getTypeSize(Context.VoidPtrTy));
+          return evalBinOpLL(state, op, lhsL, makeLoc(i), resultTy);
+        }
+        default:
+          switch (op) {
+            case BO_EQ:
+              return makeTruthVal(false, resultTy);
+            case BO_NE:
+              return makeTruthVal(true, resultTy);
+            default:
+              // This case also handles pointer arithmetic.
+              return makeGenericVal(state, op, lhs, rhs, resultTy);
+          }
+      }
+    }
+    case nonloc::ConcreteIntKind: {
+      const nonloc::ConcreteInt& lhsInt = cast<nonloc::ConcreteInt>(lhs);
+
+      // Is the RHS a symbol we can simplify?
+      // FIXME: This was mostly copy/pasted from the LHS-is-a-symbol case.
+      if (const nonloc::SymbolVal *srhs = dyn_cast<nonloc::SymbolVal>(&rhs)) {
+        SymbolRef RSym = srhs->getSymbol();
+        if (RSym->getType(Context)->isIntegerType()) {
+          if (const llvm::APSInt *Constant = state->getSymVal(RSym)) {
+            // The symbol evaluates to a constant.
+            const llvm::APSInt *rhs_I;
+            if (BinaryOperator::isRelationalOp(op))
+              rhs_I = &BasicVals.Convert(lhsInt.getValue(), *Constant);
+            else
+              rhs_I = &BasicVals.Convert(resultTy, *Constant);
+
+            rhs = nonloc::ConcreteInt(*rhs_I);
+          }
+        }
+      }
+
+      if (isa<nonloc::ConcreteInt>(rhs)) {
+        return lhsInt.evalBinOp(*this, op, cast<nonloc::ConcreteInt>(rhs));
+      } else {
+        const llvm::APSInt& lhsValue = lhsInt.getValue();
+        
+        // Swap the left and right sides and flip the operator if doing so
+        // allows us to better reason about the expression (this is a form
+        // of expression canonicalization).
+        // While we're at it, catch some special cases for non-commutative ops.
+        NonLoc tmp = rhs;
+        rhs = lhs;
+        lhs = tmp;
+
+        switch (op) {
+          case BO_LT:
+          case BO_GT:
+          case BO_LE:
+          case BO_GE:
+            op = ReverseComparison(op);
+            continue;
+          case BO_EQ:
+          case BO_NE:
+          case BO_Add:
+          case BO_Mul:
+          case BO_And:
+          case BO_Xor:
+          case BO_Or:
+            continue;
+          case BO_Shr:
+            if (lhsValue.isAllOnesValue() && lhsValue.isSigned())
+              // At this point lhs and rhs have been swapped.
+              return rhs;
+            // FALL-THROUGH
+          case BO_Shl:
+            if (lhsValue == 0)
+              // At this point lhs and rhs have been swapped.
+              return rhs;
+            return makeGenericVal(state, op, rhs, lhs, resultTy);
+          default:
+            return makeGenericVal(state, op, rhs, lhs, resultTy);
+        }
+      }
+    }
+    case nonloc::SymbolValKind: {
+      nonloc::SymbolVal *selhs = cast<nonloc::SymbolVal>(&lhs);
+
+      // LHS is a symbolic expression.
+      if (selhs->isExpression()) {
+
+        // Only handle LHS of the form "$sym op constant", at least for now.
+        const SymIntExpr *symIntExpr =
+            dyn_cast<SymIntExpr>(selhs->getSymbol());
+
+        if (!symIntExpr)
+          return makeGenericVal(state, op, lhs, rhs, resultTy);
+
+        // Is this a logical not? (!x is represented as x == 0.)
+        if (op == BO_EQ && rhs.isZeroConstant()) {
+          // We know how to negate certain expressions. Simplify them here.
+
+          BinaryOperator::Opcode opc = symIntExpr->getOpcode();
+          switch (opc) {
+          default:
+            // We don't know how to negate this operation.
+            // Just handle it as if it were a normal comparison to 0.
+            break;
+          case BO_LAnd:
+          case BO_LOr:
+            llvm_unreachable("Logical operators handled by branching logic.");
+          case BO_Assign:
+          case BO_MulAssign:
+          case BO_DivAssign:
+          case BO_RemAssign:
+          case BO_AddAssign:
+          case BO_SubAssign:
+          case BO_ShlAssign:
+          case BO_ShrAssign:
+          case BO_AndAssign:
+          case BO_XorAssign:
+          case BO_OrAssign:
+          case BO_Comma:
+            llvm_unreachable("'=' and ',' operators handled by ExprEngine.");
+          case BO_PtrMemD:
+          case BO_PtrMemI:
+            llvm_unreachable("Pointer arithmetic not handled here.");
+          case BO_LT:
+          case BO_GT:
+          case BO_LE:
+          case BO_GE:
+          case BO_EQ:
+          case BO_NE:
+            // Negate the comparison and make a value.
+            opc = NegateComparison(opc);
+            assert(symIntExpr->getType(Context) == resultTy);
+            return makeNonLoc(symIntExpr->getLHS(), opc,
+                symIntExpr->getRHS(), resultTy);
+          }
+        }
+
+        // For now, only handle expressions whose RHS is a constant.
+        const nonloc::ConcreteInt *rhsInt = dyn_cast<nonloc::ConcreteInt>(&rhs);
+        if (!rhsInt)
+          return makeGenericVal(state, op, lhs, rhs, resultTy);
+
+        // If both the LHS and the current expression are additive,
+        // fold their constants.
+        if (BinaryOperator::isAdditiveOp(op)) {
+          BinaryOperator::Opcode lop = symIntExpr->getOpcode();
+          if (BinaryOperator::isAdditiveOp(lop)) {
+            // resultTy may not be the best type to convert to, but it's
+            // probably the best choice in expressions with mixed type
+            // (such as x+1U+2LL). The rules for implicit conversions should
+            // choose a reasonable type to preserve the expression, and will
+            // at least match how the value is going to be used.
+            const llvm::APSInt &first =
+                BasicVals.Convert(resultTy, symIntExpr->getRHS());
+            const llvm::APSInt &second =
+                BasicVals.Convert(resultTy, rhsInt->getValue());
+            const llvm::APSInt *newRHS;
+            if (lop == op)
+              newRHS = BasicVals.evalAPSInt(BO_Add, first, second);
+            else
+              newRHS = BasicVals.evalAPSInt(BO_Sub, first, second);
+            return MakeSymIntVal(symIntExpr->getLHS(), lop, *newRHS, resultTy);
+          }
+        }
+
+        // Otherwise, make a SymbolVal out of the expression.
+        return MakeSymIntVal(symIntExpr, op, rhsInt->getValue(), resultTy);
+
+      // LHS is a simple symbol (not a symbolic expression).
+      } else {
+        nonloc::SymbolVal *slhs = cast<nonloc::SymbolVal>(&lhs);
+        SymbolRef Sym = slhs->getSymbol();
+        QualType lhsType = Sym->getType(Context);
+
+        // The conversion type is usually the result type, but not in the case
+        // of relational expressions.
+        QualType conversionType = resultTy;
+        if (BinaryOperator::isRelationalOp(op))
+          conversionType = lhsType;
+
+        // Does the symbol simplify to a constant?  If so, "fold" the constant
+        // by setting 'lhs' to a ConcreteInt and try again.
+        if (lhsType->isIntegerType())
+          if (const llvm::APSInt *Constant = state->getSymVal(Sym)) {
+            // The symbol evaluates to a constant. If necessary, promote the
+            // folded constant (LHS) to the result type.
+            const llvm::APSInt &lhs_I = BasicVals.Convert(conversionType,
+                *Constant);
+            lhs = nonloc::ConcreteInt(lhs_I);
+
+            // Also promote the RHS (if necessary).
+
+            // For shifts, it is not necessary to promote the RHS.
+            if (BinaryOperator::isShiftOp(op))
+              continue;
+
+            // Other operators: do an implicit conversion.  This shouldn't be
+            // necessary once we support truncation/extension of symbolic values.
+            if (nonloc::ConcreteInt *rhs_I = dyn_cast<nonloc::ConcreteInt>(&rhs)){
+              rhs = nonloc::ConcreteInt(BasicVals.Convert(conversionType,
+                  rhs_I->getValue()));
+            }
+
+            continue;
+          }
+
+        // Is the RHS a symbol we can simplify?
+        if (const nonloc::SymbolVal *srhs = dyn_cast<nonloc::SymbolVal>(&rhs)) {
+          SymbolRef RSym = srhs->getSymbol();
+          if (RSym->getType(Context)->isIntegerType()) {
+            if (const llvm::APSInt *Constant = state->getSymVal(RSym)) {
+              // The symbol evaluates to a constant.
+              const llvm::APSInt &rhs_I = BasicVals.Convert(conversionType,
+                  *Constant);
+              rhs = nonloc::ConcreteInt(rhs_I);
+            }
+          }
+        }
+
+        if (isa<nonloc::ConcreteInt>(rhs)) {
+          return MakeSymIntVal(slhs->getSymbol(), op,
+              cast<nonloc::ConcreteInt>(rhs).getValue(),
+              resultTy);
+        }
+
+        return makeGenericVal(state, op, lhs, rhs, resultTy);
+      }
+    }
+    }
+  }
+}
+
+// FIXME: all this logic will change if/when we have MemRegion::getLocation().
+SVal SimpleSValBuilder::evalBinOpLL(ProgramStateRef state,
+                                  BinaryOperator::Opcode op,
+                                  Loc lhs, Loc rhs,
+                                  QualType resultTy) {
+  // Only comparisons and subtractions are valid operations on two pointers.
+  // See [C99 6.5.5 through 6.5.14] or [C++0x 5.6 through 5.15].
+  // However, if a pointer is casted to an integer, evalBinOpNN may end up
+  // calling this function with another operation (PR7527). We don't attempt to
+  // model this for now, but it could be useful, particularly when the
+  // "location" is actually an integer value that's been passed through a void*.
+  if (!(BinaryOperator::isComparisonOp(op) || op == BO_Sub))
+    return UnknownVal();
+
+  // Special cases for when both sides are identical.
+  if (lhs == rhs) {
+    switch (op) {
+    default:
+      llvm_unreachable("Unimplemented operation for two identical values");
+    case BO_Sub:
+      return makeZeroVal(resultTy);
+    case BO_EQ:
+    case BO_LE:
+    case BO_GE:
+      return makeTruthVal(true, resultTy);
+    case BO_NE:
+    case BO_LT:
+    case BO_GT:
+      return makeTruthVal(false, resultTy);
+    }
+  }
+
+  switch (lhs.getSubKind()) {
+  default:
+    llvm_unreachable("Ordering not implemented for this Loc.");
+
+  case loc::GotoLabelKind:
+    // The only thing we know about labels is that they're non-null.
+    if (rhs.isZeroConstant()) {
+      switch (op) {
+      default:
+        break;
+      case BO_Sub:
+        return evalCastFromLoc(lhs, resultTy);
+      case BO_EQ:
+      case BO_LE:
+      case BO_LT:
+        return makeTruthVal(false, resultTy);
+      case BO_NE:
+      case BO_GT:
+      case BO_GE:
+        return makeTruthVal(true, resultTy);
+      }
+    }
+    // There may be two labels for the same location, and a function region may
+    // have the same address as a label at the start of the function (depending
+    // on the ABI).
+    // FIXME: we can probably do a comparison against other MemRegions, though.
+    // FIXME: is there a way to tell if two labels refer to the same location?
+    return UnknownVal(); 
+
+  case loc::ConcreteIntKind: {
+    // If one of the operands is a symbol and the other is a constant,
+    // build an expression for use by the constraint manager.
+    if (SymbolRef rSym = rhs.getAsLocSymbol()) {
+      // We can only build expressions with symbols on the left,
+      // so we need a reversible operator.
+      if (!BinaryOperator::isComparisonOp(op))
+        return UnknownVal();
+
+      const llvm::APSInt &lVal = cast<loc::ConcreteInt>(lhs).getValue();
+      return makeNonLoc(rSym, ReverseComparison(op), lVal, resultTy);
+    }
+
+    // If both operands are constants, just perform the operation.
+    if (loc::ConcreteInt *rInt = dyn_cast<loc::ConcreteInt>(&rhs)) {
+      SVal ResultVal = cast<loc::ConcreteInt>(lhs).evalBinOp(BasicVals, op,
+                                                             *rInt);
+      if (Loc *Result = dyn_cast<Loc>(&ResultVal))
+        return evalCastFromLoc(*Result, resultTy);
+      else
+        return UnknownVal();
+    }
+
+    // Special case comparisons against NULL.
+    // This must come after the test if the RHS is a symbol, which is used to
+    // build constraints. The address of any non-symbolic region is guaranteed
+    // to be non-NULL, as is any label.
+    assert(isa<loc::MemRegionVal>(rhs) || isa<loc::GotoLabel>(rhs));
+    if (lhs.isZeroConstant()) {
+      switch (op) {
+      default:
+        break;
+      case BO_EQ:
+      case BO_GT:
+      case BO_GE:
+        return makeTruthVal(false, resultTy);
+      case BO_NE:
+      case BO_LT:
+      case BO_LE:
+        return makeTruthVal(true, resultTy);
+      }
+    }
+
+    // Comparing an arbitrary integer to a region or label address is
+    // completely unknowable.
+    return UnknownVal();
+  }
+  case loc::MemRegionKind: {
+    if (loc::ConcreteInt *rInt = dyn_cast<loc::ConcreteInt>(&rhs)) {
+      // If one of the operands is a symbol and the other is a constant,
+      // build an expression for use by the constraint manager.
+      if (SymbolRef lSym = lhs.getAsLocSymbol())
+        return MakeSymIntVal(lSym, op, rInt->getValue(), resultTy);
+
+      // Special case comparisons to NULL.
+      // This must come after the test if the LHS is a symbol, which is used to
+      // build constraints. The address of any non-symbolic region is guaranteed
+      // to be non-NULL.
+      if (rInt->isZeroConstant()) {
+        switch (op) {
+        default:
+          break;
+        case BO_Sub:
+          return evalCastFromLoc(lhs, resultTy);
+        case BO_EQ:
+        case BO_LT:
+        case BO_LE:
+          return makeTruthVal(false, resultTy);
+        case BO_NE:
+        case BO_GT:
+        case BO_GE:
+          return makeTruthVal(true, resultTy);
+        }
+      }
+
+      // Comparing a region to an arbitrary integer is completely unknowable.
+      return UnknownVal();
+    }
+
+    // Get both values as regions, if possible.
+    const MemRegion *LeftMR = lhs.getAsRegion();
+    assert(LeftMR && "MemRegionKind SVal doesn't have a region!");
+
+    const MemRegion *RightMR = rhs.getAsRegion();
+    if (!RightMR)
+      // The RHS is probably a label, which in theory could address a region.
+      // FIXME: we can probably make a more useful statement about non-code
+      // regions, though.
+      return UnknownVal();
+
+    // If both values wrap regions, see if they're from different base regions.
+    const MemRegion *LeftBase = LeftMR->getBaseRegion();
+    const MemRegion *RightBase = RightMR->getBaseRegion();
+    if (LeftBase != RightBase &&
+        !isa<SymbolicRegion>(LeftBase) && !isa<SymbolicRegion>(RightBase)) {
+      switch (op) {
+      default:
+        return UnknownVal();
+      case BO_EQ:
+        return makeTruthVal(false, resultTy);
+      case BO_NE:
+        return makeTruthVal(true, resultTy);
+      }
+    }
+
+    // The two regions are from the same base region. See if they're both a
+    // type of region we know how to compare.
+    const MemSpaceRegion *LeftMS = LeftBase->getMemorySpace();
+    const MemSpaceRegion *RightMS = RightBase->getMemorySpace();
+
+    // Heuristic: assume that no symbolic region (whose memory space is
+    // unknown) is on the stack.
+    // FIXME: we should be able to be more precise once we can do better
+    // aliasing constraints for symbolic regions, but this is a reasonable,
+    // albeit unsound, assumption that holds most of the time.
+    if (isa<StackSpaceRegion>(LeftMS) ^ isa<StackSpaceRegion>(RightMS)) {
+      switch (op) {
+        default:
+          break;
+        case BO_EQ:
+          return makeTruthVal(false, resultTy);
+        case BO_NE:
+          return makeTruthVal(true, resultTy);
+      }
+    }
+
+    // FIXME: If/when there is a getAsRawOffset() for FieldRegions, this
+    // ElementRegion path and the FieldRegion path below should be unified.
+    if (const ElementRegion *LeftER = dyn_cast<ElementRegion>(LeftMR)) {
+      // First see if the right region is also an ElementRegion.
+      const ElementRegion *RightER = dyn_cast<ElementRegion>(RightMR);
+      if (!RightER)
+        return UnknownVal();
+
+      // Next, see if the two ERs have the same super-region and matching types.
+      // FIXME: This should do something useful even if the types don't match,
+      // though if both indexes are constant the RegionRawOffset path will
+      // give the correct answer.
+      if (LeftER->getSuperRegion() == RightER->getSuperRegion() &&
+          LeftER->getElementType() == RightER->getElementType()) {
+        // Get the left index and cast it to the correct type.
+        // If the index is unknown or undefined, bail out here.
+        SVal LeftIndexVal = LeftER->getIndex();
+        NonLoc *LeftIndex = dyn_cast<NonLoc>(&LeftIndexVal);
+        if (!LeftIndex)
+          return UnknownVal();
+        LeftIndexVal = evalCastFromNonLoc(*LeftIndex, resultTy);
+        LeftIndex = dyn_cast<NonLoc>(&LeftIndexVal);
+        if (!LeftIndex)
+          return UnknownVal();
+
+        // Do the same for the right index.
+        SVal RightIndexVal = RightER->getIndex();
+        NonLoc *RightIndex = dyn_cast<NonLoc>(&RightIndexVal);
+        if (!RightIndex)
+          return UnknownVal();
+        RightIndexVal = evalCastFromNonLoc(*RightIndex, resultTy);
+        RightIndex = dyn_cast<NonLoc>(&RightIndexVal);
+        if (!RightIndex)
+          return UnknownVal();
+
+        // Actually perform the operation.
+        // evalBinOpNN expects the two indexes to already be the right type.
+        return evalBinOpNN(state, op, *LeftIndex, *RightIndex, resultTy);
+      }
+
+      // If the element indexes aren't comparable, see if the raw offsets are.
+      RegionRawOffset LeftOffset = LeftER->getAsArrayOffset();
+      RegionRawOffset RightOffset = RightER->getAsArrayOffset();
+
+      if (LeftOffset.getRegion() != NULL &&
+          LeftOffset.getRegion() == RightOffset.getRegion()) {
+        CharUnits left = LeftOffset.getOffset();
+        CharUnits right = RightOffset.getOffset();
+
+        switch (op) {
+        default:
+          return UnknownVal();
+        case BO_LT:
+          return makeTruthVal(left < right, resultTy);
+        case BO_GT:
+          return makeTruthVal(left > right, resultTy);
+        case BO_LE:
+          return makeTruthVal(left <= right, resultTy);
+        case BO_GE:
+          return makeTruthVal(left >= right, resultTy);
+        case BO_EQ:
+          return makeTruthVal(left == right, resultTy);
+        case BO_NE:
+          return makeTruthVal(left != right, resultTy);
+        }
+      }
+
+      // If we get here, we have no way of comparing the ElementRegions.
+      return UnknownVal();
+    }
+
+    // See if both regions are fields of the same structure.
+    // FIXME: This doesn't handle nesting, inheritance, or Objective-C ivars.
+    if (const FieldRegion *LeftFR = dyn_cast<FieldRegion>(LeftMR)) {
+      // Only comparisons are meaningful here!
+      if (!BinaryOperator::isComparisonOp(op))
+        return UnknownVal();
+
+      // First see if the right region is also a FieldRegion.
+      const FieldRegion *RightFR = dyn_cast<FieldRegion>(RightMR);
+      if (!RightFR)
+        return UnknownVal();
+
+      // Next, see if the two FRs have the same super-region.
+      // FIXME: This doesn't handle casts yet, and simply stripping the casts
+      // doesn't help.
+      if (LeftFR->getSuperRegion() != RightFR->getSuperRegion())
+        return UnknownVal();
+
+      const FieldDecl *LeftFD = LeftFR->getDecl();
+      const FieldDecl *RightFD = RightFR->getDecl();
+      const RecordDecl *RD = LeftFD->getParent();
+
+      // Make sure the two FRs are from the same kind of record. Just in case!
+      // FIXME: This is probably where inheritance would be a problem.
+      if (RD != RightFD->getParent())
+        return UnknownVal();
+
+      // We know for sure that the two fields are not the same, since that
+      // would have given us the same SVal.
+      if (op == BO_EQ)
+        return makeTruthVal(false, resultTy);
+      if (op == BO_NE)
+        return makeTruthVal(true, resultTy);
+
+      // Iterate through the fields and see which one comes first.
+      // [C99 6.7.2.1.13] "Within a structure object, the non-bit-field
+      // members and the units in which bit-fields reside have addresses that
+      // increase in the order in which they are declared."
+      bool leftFirst = (op == BO_LT || op == BO_LE);
+      for (RecordDecl::field_iterator I = RD->field_begin(),
+           E = RD->field_end(); I!=E; ++I) {
+        if (*I == LeftFD)
+          return makeTruthVal(leftFirst, resultTy);
+        if (*I == RightFD)
+          return makeTruthVal(!leftFirst, resultTy);
+      }
+
+      llvm_unreachable("Fields not found in parent record's definition");
+    }
+
+    // If we get here, we have no way of comparing the regions.
+    return UnknownVal();
+  }
+  }
+}
+
+SVal SimpleSValBuilder::evalBinOpLN(ProgramStateRef state,
+                                  BinaryOperator::Opcode op,
+                                  Loc lhs, NonLoc rhs, QualType resultTy) {
+  
+  // Special case: rhs is a zero constant.
+  if (rhs.isZeroConstant())
+    return lhs;
+  
+  // Special case: 'rhs' is an integer that has the same width as a pointer and
+  // we are using the integer location in a comparison.  Normally this cannot be
+  // triggered, but transfer functions like those for OSCommpareAndSwapBarrier32
+  // can generate comparisons that trigger this code.
+  // FIXME: Are all locations guaranteed to have pointer width?
+  if (BinaryOperator::isComparisonOp(op)) {
+    if (nonloc::ConcreteInt *rhsInt = dyn_cast<nonloc::ConcreteInt>(&rhs)) {
+      const llvm::APSInt *x = &rhsInt->getValue();
+      ASTContext &ctx = Context;
+      if (ctx.getTypeSize(ctx.VoidPtrTy) == x->getBitWidth()) {
+        // Convert the signedness of the integer (if necessary).
+        if (x->isSigned())
+          x = &getBasicValueFactory().getValue(*x, true);
+
+        return evalBinOpLL(state, op, lhs, loc::ConcreteInt(*x), resultTy);
+      }
+    }
+  }
+  
+  // We are dealing with pointer arithmetic.
+
+  // Handle pointer arithmetic on constant values.
+  if (nonloc::ConcreteInt *rhsInt = dyn_cast<nonloc::ConcreteInt>(&rhs)) {
+    if (loc::ConcreteInt *lhsInt = dyn_cast<loc::ConcreteInt>(&lhs)) {
+      const llvm::APSInt &leftI = lhsInt->getValue();
+      assert(leftI.isUnsigned());
+      llvm::APSInt rightI(rhsInt->getValue(), /* isUnsigned */ true);
+
+      // Convert the bitwidth of rightI.  This should deal with overflow
+      // since we are dealing with concrete values.
+      rightI = rightI.extOrTrunc(leftI.getBitWidth());
+
+      // Offset the increment by the pointer size.
+      llvm::APSInt Multiplicand(rightI.getBitWidth(), /* isUnsigned */ true);
+      rightI *= Multiplicand;
+      
+      // Compute the adjusted pointer.
+      switch (op) {
+        case BO_Add:
+          rightI = leftI + rightI;
+          break;
+        case BO_Sub:
+          rightI = leftI - rightI;
+          break;
+        default:
+          llvm_unreachable("Invalid pointer arithmetic operation");
+      }
+      return loc::ConcreteInt(getBasicValueFactory().getValue(rightI));
+    }
+  }
+
+  // Handle cases where 'lhs' is a region.
+  if (const MemRegion *region = lhs.getAsRegion()) {
+    rhs = cast<NonLoc>(convertToArrayIndex(rhs));
+    SVal index = UnknownVal();
+    const MemRegion *superR = 0;
+    QualType elementType;
+
+    if (const ElementRegion *elemReg = dyn_cast<ElementRegion>(region)) {
+      assert(op == BO_Add || op == BO_Sub);
+      index = evalBinOpNN(state, op, elemReg->getIndex(), rhs,
+                          getArrayIndexType());
+      superR = elemReg->getSuperRegion();
+      elementType = elemReg->getElementType();
+    }
+    else if (isa<SubRegion>(region)) {
+      superR = region;
+      index = rhs;
+      if (const PointerType *PT = resultTy->getAs<PointerType>()) {
+        elementType = PT->getPointeeType();
+      }
+      else {
+        const ObjCObjectPointerType *OT =
+          resultTy->getAs<ObjCObjectPointerType>();
+        elementType = OT->getPointeeType();
+      }
+    }
+
+    if (NonLoc *indexV = dyn_cast<NonLoc>(&index)) {
+      return loc::MemRegionVal(MemMgr.getElementRegion(elementType, *indexV,
+                                                       superR, getContext()));
+    }
+  }
+  return UnknownVal();  
+}
+
+const llvm::APSInt *SimpleSValBuilder::getKnownValue(ProgramStateRef state,
+                                                   SVal V) {
+  if (V.isUnknownOrUndef())
+    return NULL;
+
+  if (loc::ConcreteInt* X = dyn_cast<loc::ConcreteInt>(&V))
+    return &X->getValue();
+
+  if (nonloc::ConcreteInt* X = dyn_cast<nonloc::ConcreteInt>(&V))
+    return &X->getValue();
+
+  if (SymbolRef Sym = V.getAsSymbol())
+    return state->getSymVal(Sym);
+
+  // FIXME: Add support for SymExprs.
+  return NULL;
+}