Import Clang, at r72732.

1 files changed, 1723 insertions, 0 deletions

diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
new file mode 100644
index 0000000..50fdcfd
--- /dev/null
+++ b/lib/AST/ExprConstant.cpp
@@ -0,0 +1,1723 @@
+//===--- ExprConstant.cpp - Expression Constant Evaluator -----------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the Expr constant evaluator.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/APValue.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/RecordLayout.h"
+#include "clang/AST/StmtVisitor.h"
+#include "clang/AST/ASTDiagnostic.h"
+#include "clang/Basic/TargetInfo.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/Support/Compiler.h"
+#include <cstring>
+
+using namespace clang;
+using llvm::APSInt;
+using llvm::APFloat;
+
+/// EvalInfo - This is a private struct used by the evaluator to capture
+/// information about a subexpression as it is folded.  It retains information
+/// about the AST context, but also maintains information about the folded
+/// expression.
+///
+/// If an expression could be evaluated, it is still possible it is not a C
+/// "integer constant expression" or constant expression.  If not, this struct
+/// captures information about how and why not.
+///
+/// One bit of information passed *into* the request for constant folding
+/// indicates whether the subexpression is "evaluated" or not according to C
+/// rules.  For example, the RHS of (0 && foo()) is not evaluated.  We can
+/// evaluate the expression regardless of what the RHS is, but C only allows
+/// certain things in certain situations.
+struct EvalInfo {
+  ASTContext &Ctx;
+  
+  /// EvalResult - Contains information about the evaluation.
+  Expr::EvalResult &EvalResult;
+
+  EvalInfo(ASTContext &ctx, Expr::EvalResult& evalresult) : Ctx(ctx), 
+           EvalResult(evalresult) {}
+};
+
+
+static bool EvaluateLValue(const Expr *E, APValue &Result, EvalInfo &Info);
+static bool EvaluatePointer(const Expr *E, APValue &Result, EvalInfo &Info);
+static bool EvaluateInteger(const Expr *E, APSInt  &Result, EvalInfo &Info);
+static bool EvaluateIntegerOrLValue(const Expr *E, APValue  &Result, EvalInfo &Info);
+static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info);
+static bool EvaluateComplex(const Expr *E, APValue &Result, EvalInfo &Info);
+
+//===----------------------------------------------------------------------===//
+// Misc utilities
+//===----------------------------------------------------------------------===//
+
+static bool HandleConversionToBool(Expr* E, bool& Result, EvalInfo &Info) {
+  if (E->getType()->isIntegralType()) {
+    APSInt IntResult;
+    if (!EvaluateInteger(E, IntResult, Info))
+      return false;
+    Result = IntResult != 0;
+    return true;
+  } else if (E->getType()->isRealFloatingType()) {
+    APFloat FloatResult(0.0);
+    if (!EvaluateFloat(E, FloatResult, Info))
+      return false;
+    Result = !FloatResult.isZero();
+    return true;
+  } else if (E->getType()->hasPointerRepresentation()) {
+    APValue PointerResult;
+    if (!EvaluatePointer(E, PointerResult, Info))
+      return false;
+    // FIXME: Is this accurate for all kinds of bases?  If not, what would
+    // the check look like?
+    Result = PointerResult.getLValueBase() || PointerResult.getLValueOffset();
+    return true;
+  } else if (E->getType()->isAnyComplexType()) {
+    APValue ComplexResult;
+    if (!EvaluateComplex(E, ComplexResult, Info))
+      return false;
+    if (ComplexResult.isComplexFloat()) {
+      Result = !ComplexResult.getComplexFloatReal().isZero() ||
+               !ComplexResult.getComplexFloatImag().isZero();
+    } else {
+      Result = ComplexResult.getComplexIntReal().getBoolValue() ||
+               ComplexResult.getComplexIntImag().getBoolValue();
+    }
+    return true;
+  }
+
+  return false;
+}
+
+static APSInt HandleFloatToIntCast(QualType DestType, QualType SrcType, 
+                                   APFloat &Value, ASTContext &Ctx) {
+  unsigned DestWidth = Ctx.getIntWidth(DestType);
+  // Determine whether we are converting to unsigned or signed.
+  bool DestSigned = DestType->isSignedIntegerType();
+  
+  // FIXME: Warning for overflow.
+  uint64_t Space[4];
+  bool ignored;
+  (void)Value.convertToInteger(Space, DestWidth, DestSigned,
+                               llvm::APFloat::rmTowardZero, &ignored);
+  return APSInt(llvm::APInt(DestWidth, 4, Space), !DestSigned);
+}
+
+static APFloat HandleFloatToFloatCast(QualType DestType, QualType SrcType, 
+                                      APFloat &Value, ASTContext &Ctx) {
+  bool ignored;
+  APFloat Result = Value;
+  Result.convert(Ctx.getFloatTypeSemantics(DestType), 
+                 APFloat::rmNearestTiesToEven, &ignored);
+  return Result;
+}
+
+static APSInt HandleIntToIntCast(QualType DestType, QualType SrcType, 
+                                 APSInt &Value, ASTContext &Ctx) {
+  unsigned DestWidth = Ctx.getIntWidth(DestType);
+  APSInt Result = Value;
+  // Figure out if this is a truncate, extend or noop cast.
+  // If the input is signed, do a sign extend, noop, or truncate.
+  Result.extOrTrunc(DestWidth);
+  Result.setIsUnsigned(DestType->isUnsignedIntegerType());
+  return Result;
+}
+
+static APFloat HandleIntToFloatCast(QualType DestType, QualType SrcType, 
+                                    APSInt &Value, ASTContext &Ctx) {
+
+  APFloat Result(Ctx.getFloatTypeSemantics(DestType), 1);
+  Result.convertFromAPInt(Value, Value.isSigned(),
+                          APFloat::rmNearestTiesToEven);
+  return Result;
+}
+
+//===----------------------------------------------------------------------===//
+// LValue Evaluation
+//===----------------------------------------------------------------------===//
+namespace {
+class VISIBILITY_HIDDEN LValueExprEvaluator
+  : public StmtVisitor<LValueExprEvaluator, APValue> {
+  EvalInfo &Info;
+public:
+    
+  LValueExprEvaluator(EvalInfo &info) : Info(info) {}
+
+  APValue VisitStmt(Stmt *S) {
+    return APValue();
+  }
+
+  APValue VisitParenExpr(ParenExpr *E) { return Visit(E->getSubExpr()); }
+  APValue VisitDeclRefExpr(DeclRefExpr *E);
+  APValue VisitBlockExpr(BlockExpr *E);
+  APValue VisitPredefinedExpr(PredefinedExpr *E) { return APValue(E, 0); }
+  APValue VisitCompoundLiteralExpr(CompoundLiteralExpr *E);
+  APValue VisitMemberExpr(MemberExpr *E);
+  APValue VisitStringLiteral(StringLiteral *E) { return APValue(E, 0); }
+  APValue VisitObjCEncodeExpr(ObjCEncodeExpr *E) { return APValue(E, 0); }
+  APValue VisitArraySubscriptExpr(ArraySubscriptExpr *E);
+  APValue VisitUnaryDeref(UnaryOperator *E);
+  APValue VisitUnaryExtension(const UnaryOperator *E)
+    { return Visit(E->getSubExpr()); }
+  APValue VisitChooseExpr(const ChooseExpr *E)
+    { return Visit(E->getChosenSubExpr(Info.Ctx)); }
+  // FIXME: Missing: __real__, __imag__
+};
+} // end anonymous namespace
+
+static bool EvaluateLValue(const Expr* E, APValue& Result, EvalInfo &Info) {
+  Result = LValueExprEvaluator(Info).Visit(const_cast<Expr*>(E));
+  return Result.isLValue();
+}
+
+APValue LValueExprEvaluator::VisitDeclRefExpr(DeclRefExpr *E)
+{
+  if (!E->hasGlobalStorage())
+    return APValue();
+
+  if (isa<FunctionDecl>(E->getDecl())) {
+    return APValue(E, 0);
+  } else if (VarDecl* VD = dyn_cast<VarDecl>(E->getDecl())) {
+    if (!VD->getType()->isReferenceType())
+      return APValue(E, 0);
+    if (VD->getInit())
+      return Visit(VD->getInit());
+  }
+
+  return APValue();
+}
+
+APValue LValueExprEvaluator::VisitBlockExpr(BlockExpr *E)
+{ 
+  if (E->hasBlockDeclRefExprs())
+    return APValue();
+    
+  return APValue(E, 0);
+}
+
+APValue LValueExprEvaluator::VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
+  if (E->isFileScope())
+    return APValue(E, 0);
+  return APValue();
+}
+
+APValue LValueExprEvaluator::VisitMemberExpr(MemberExpr *E) {
+  APValue result;
+  QualType Ty;
+  if (E->isArrow()) {
+    if (!EvaluatePointer(E->getBase(), result, Info))
+      return APValue();
+    Ty = E->getBase()->getType()->getAsPointerType()->getPointeeType();
+  } else {
+    result = Visit(E->getBase());
+    if (result.isUninit())
+      return APValue();
+    Ty = E->getBase()->getType();
+  }
+
+  RecordDecl *RD = Ty->getAsRecordType()->getDecl();
+  const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD);
+
+  FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl());
+  if (!FD) // FIXME: deal with other kinds of member expressions
+    return APValue();
+
+  if (FD->getType()->isReferenceType())
+    return APValue();
+
+  // FIXME: This is linear time.
+  unsigned i = 0;
+  for (RecordDecl::field_iterator Field = RD->field_begin(Info.Ctx),
+                               FieldEnd = RD->field_end(Info.Ctx);
+       Field != FieldEnd; (void)++Field, ++i) {
+    if (*Field == FD)
+      break;
+  }
+
+  result.setLValue(result.getLValueBase(),
+                   result.getLValueOffset() + RL.getFieldOffset(i) / 8);
+
+  return result;
+}
+
+APValue LValueExprEvaluator::VisitArraySubscriptExpr(ArraySubscriptExpr *E)
+{
+  APValue Result;
+  
+  if (!EvaluatePointer(E->getBase(), Result, Info))
+    return APValue();
+  
+  APSInt Index;
+  if (!EvaluateInteger(E->getIdx(), Index, Info))
+    return APValue();
+
+  uint64_t ElementSize = Info.Ctx.getTypeSize(E->getType()) / 8;
+
+  uint64_t Offset = Index.getSExtValue() * ElementSize;
+  Result.setLValue(Result.getLValueBase(), 
+                   Result.getLValueOffset() + Offset);
+  return Result;
+}
+
+APValue LValueExprEvaluator::VisitUnaryDeref(UnaryOperator *E)
+{
+  APValue Result;
+  if (!EvaluatePointer(E->getSubExpr(), Result, Info))
+    return APValue();
+  return Result;
+}
+
+//===----------------------------------------------------------------------===//
+// Pointer Evaluation
+//===----------------------------------------------------------------------===//
+
+namespace {
+class VISIBILITY_HIDDEN PointerExprEvaluator
+  : public StmtVisitor<PointerExprEvaluator, APValue> {
+  EvalInfo &Info;
+public:
+    
+  PointerExprEvaluator(EvalInfo &info) : Info(info) {}
+
+  APValue VisitStmt(Stmt *S) {
+    return APValue();
+  }
+
+  APValue VisitParenExpr(ParenExpr *E) { return Visit(E->getSubExpr()); }
+
+  APValue VisitBinaryOperator(const BinaryOperator *E);
+  APValue VisitCastExpr(const CastExpr* E);
+  APValue VisitUnaryExtension(const UnaryOperator *E)
+      { return Visit(E->getSubExpr()); }
+  APValue VisitUnaryAddrOf(const UnaryOperator *E);
+  APValue VisitObjCStringLiteral(ObjCStringLiteral *E)
+      { return APValue(E, 0); }
+  APValue VisitAddrLabelExpr(AddrLabelExpr *E)
+      { return APValue(E, 0); }
+  APValue VisitCallExpr(CallExpr *E);
+  APValue VisitBlockExpr(BlockExpr *E) {
+    if (!E->hasBlockDeclRefExprs())
+      return APValue(E, 0);
+    return APValue();
+  }
+  APValue VisitImplicitValueInitExpr(ImplicitValueInitExpr *E)
+      { return APValue((Expr*)0, 0); }
+  APValue VisitConditionalOperator(ConditionalOperator *E);
+  APValue VisitChooseExpr(ChooseExpr *E)
+      { return Visit(E->getChosenSubExpr(Info.Ctx)); }
+  APValue VisitCXXNullPtrLiteralExpr(CXXNullPtrLiteralExpr *E)
+      { return APValue((Expr*)0, 0); }
+  // FIXME: Missing: @protocol, @selector
+};
+} // end anonymous namespace
+
+static bool EvaluatePointer(const Expr* E, APValue& Result, EvalInfo &Info) {
+  if (!E->getType()->hasPointerRepresentation())
+    return false;
+  Result = PointerExprEvaluator(Info).Visit(const_cast<Expr*>(E));
+  return Result.isLValue();
+}
+
+APValue PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
+  if (E->getOpcode() != BinaryOperator::Add &&
+      E->getOpcode() != BinaryOperator::Sub)
+    return APValue();
+  
+  const Expr *PExp = E->getLHS();
+  const Expr *IExp = E->getRHS();
+  if (IExp->getType()->isPointerType())
+    std::swap(PExp, IExp);
+  
+  APValue ResultLValue;
+  if (!EvaluatePointer(PExp, ResultLValue, Info))
+    return APValue();
+  
+  llvm::APSInt AdditionalOffset(32);
+  if (!EvaluateInteger(IExp, AdditionalOffset, Info))
+    return APValue();
+
+  QualType PointeeType = PExp->getType()->getAsPointerType()->getPointeeType();
+  uint64_t SizeOfPointee;
+  
+  // Explicitly handle GNU void* and function pointer arithmetic extensions.
+  if (PointeeType->isVoidType() || PointeeType->isFunctionType())
+    SizeOfPointee = 1;
+  else
+    SizeOfPointee = Info.Ctx.getTypeSize(PointeeType) / 8;
+
+  uint64_t Offset = ResultLValue.getLValueOffset();
+
+  if (E->getOpcode() == BinaryOperator::Add)
+    Offset += AdditionalOffset.getLimitedValue() * SizeOfPointee;
+  else
+    Offset -= AdditionalOffset.getLimitedValue() * SizeOfPointee;
+
+  return APValue(ResultLValue.getLValueBase(), Offset);
+}
+
+APValue PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {
+  APValue result;
+  if (EvaluateLValue(E->getSubExpr(), result, Info))
+    return result;
+  return APValue();
+}
+  
+
+APValue PointerExprEvaluator::VisitCastExpr(const CastExpr* E) {
+  const Expr* SubExpr = E->getSubExpr();
+
+   // Check for pointer->pointer cast
+  if (SubExpr->getType()->isPointerType()) {
+    APValue Result;
+    if (EvaluatePointer(SubExpr, Result, Info))
+      return Result;
+    return APValue();
+  }
+  
+  if (SubExpr->getType()->isIntegralType()) {
+    APValue Result;
+    if (!EvaluateIntegerOrLValue(SubExpr, Result, Info))
+      return APValue();
+
+    if (Result.isInt()) {
+      Result.getInt().extOrTrunc((unsigned)Info.Ctx.getTypeSize(E->getType()));
+      return APValue(0, Result.getInt().getZExtValue());
+    }
+    
+    // Cast is of an lvalue, no need to change value.
+    return Result;
+  }
+
+  if (SubExpr->getType()->isFunctionType() ||
+      SubExpr->getType()->isBlockPointerType() ||
+      SubExpr->getType()->isArrayType()) {
+    APValue Result;
+    if (EvaluateLValue(SubExpr, Result, Info))
+      return Result;
+    return APValue();
+  }
+
+  return APValue();
+}  
+
+APValue PointerExprEvaluator::VisitCallExpr(CallExpr *E) {
+  if (E->isBuiltinCall(Info.Ctx) == 
+        Builtin::BI__builtin___CFStringMakeConstantString)
+    return APValue(E, 0);
+  return APValue();
+}
+
+APValue PointerExprEvaluator::VisitConditionalOperator(ConditionalOperator *E) {
+  bool BoolResult;
+  if (!HandleConversionToBool(E->getCond(), BoolResult, Info))
+    return APValue();
+
+  Expr* EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr();
+
+  APValue Result;
+  if (EvaluatePointer(EvalExpr, Result, Info))
+    return Result;
+  return APValue();
+}
+
+//===----------------------------------------------------------------------===//
+// Vector Evaluation
+//===----------------------------------------------------------------------===//
+
+namespace {
+  class VISIBILITY_HIDDEN VectorExprEvaluator
+  : public StmtVisitor<VectorExprEvaluator, APValue> {
+    EvalInfo &Info;
+    APValue GetZeroVector(QualType VecType);
+  public:
+    
+    VectorExprEvaluator(EvalInfo &info) : Info(info) {}
+    
+    APValue VisitStmt(Stmt *S) {
+      return APValue();
+    }
+    
+    APValue VisitParenExpr(ParenExpr *E)
+        { return Visit(E->getSubExpr()); }
+    APValue VisitUnaryExtension(const UnaryOperator *E)
+      { return Visit(E->getSubExpr()); }
+    APValue VisitUnaryPlus(const UnaryOperator *E)
+      { return Visit(E->getSubExpr()); }
+    APValue VisitUnaryReal(const UnaryOperator *E)
+      { return Visit(E->getSubExpr()); }
+    APValue VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E)
+      { return GetZeroVector(E->getType()); }
+    APValue VisitCastExpr(const CastExpr* E);
+    APValue VisitCompoundLiteralExpr(const CompoundLiteralExpr *E);
+    APValue VisitInitListExpr(const InitListExpr *E);
+    APValue VisitConditionalOperator(const ConditionalOperator *E);
+    APValue VisitChooseExpr(const ChooseExpr *E)
+      { return Visit(E->getChosenSubExpr(Info.Ctx)); }
+    APValue VisitUnaryImag(const UnaryOperator *E);
+    // FIXME: Missing: unary -, unary ~, binary add/sub/mul/div,
+    //                 binary comparisons, binary and/or/xor,
+    //                 shufflevector, ExtVectorElementExpr
+    //        (Note that these require implementing conversions
+    //         between vector types.)
+  };
+} // end anonymous namespace
+
+static bool EvaluateVector(const Expr* E, APValue& Result, EvalInfo &Info) {
+  if (!E->getType()->isVectorType())
+    return false;
+  Result = VectorExprEvaluator(Info).Visit(const_cast<Expr*>(E));
+  return !Result.isUninit();
+}
+
+APValue VectorExprEvaluator::VisitCastExpr(const CastExpr* E) {
+  const Expr* SE = E->getSubExpr();
+
+  // Check for vector->vector bitcast.
+  if (SE->getType()->isVectorType())
+    return this->Visit(const_cast<Expr*>(SE));
+
+  return APValue();
+}
+
+APValue 
+VectorExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
+  return this->Visit(const_cast<Expr*>(E->getInitializer()));
+}
+
+APValue 
+VectorExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
+  const VectorType *VT = E->getType()->getAsVectorType();
+  unsigned NumInits = E->getNumInits();
+  unsigned NumElements = VT->getNumElements();
+  
+  QualType EltTy = VT->getElementType();
+  llvm::SmallVector<APValue, 4> Elements;
+
+  for (unsigned i = 0; i < NumElements; i++) {
+    if (EltTy->isIntegerType()) {
+      llvm::APSInt sInt(32);
+      if (i < NumInits) {
+        if (!EvaluateInteger(E->getInit(i), sInt, Info))
+          return APValue();
+      } else {
+        sInt = Info.Ctx.MakeIntValue(0, EltTy);
+      }
+      Elements.push_back(APValue(sInt));
+    } else {
+      llvm::APFloat f(0.0);
+      if (i < NumInits) {
+        if (!EvaluateFloat(E->getInit(i), f, Info))
+          return APValue();
+      } else {
+        f = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy));
+      }
+      Elements.push_back(APValue(f));
+    }
+  }
+  return APValue(&Elements[0], Elements.size());
+}
+
+APValue 
+VectorExprEvaluator::GetZeroVector(QualType T) {
+  const VectorType *VT = T->getAsVectorType();
+  QualType EltTy = VT->getElementType();
+  APValue ZeroElement;
+  if (EltTy->isIntegerType())
+    ZeroElement = APValue(Info.Ctx.MakeIntValue(0, EltTy));
+  else
+    ZeroElement =
+        APValue(APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy)));
+
+  llvm::SmallVector<APValue, 4> Elements(VT->getNumElements(), ZeroElement);
+  return APValue(&Elements[0], Elements.size());
+}
+
+APValue VectorExprEvaluator::VisitConditionalOperator(const ConditionalOperator *E) {
+  bool BoolResult;
+  if (!HandleConversionToBool(E->getCond(), BoolResult, Info))
+    return APValue();
+
+  Expr* EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr();
+
+  APValue Result;
+  if (EvaluateVector(EvalExpr, Result, Info))
+    return Result;
+  return APValue();
+}
+
+APValue VectorExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
+  if (!E->getSubExpr()->isEvaluatable(Info.Ctx))
+    Info.EvalResult.HasSideEffects = true;
+  return GetZeroVector(E->getType());
+}
+
+//===----------------------------------------------------------------------===//
+// Integer Evaluation
+//===----------------------------------------------------------------------===//
+
+namespace {
+class VISIBILITY_HIDDEN IntExprEvaluator
+  : public StmtVisitor<IntExprEvaluator, bool> {
+  EvalInfo &Info;
+  APValue &Result;
+public:
+  IntExprEvaluator(EvalInfo &info, APValue &result)
+    : Info(info), Result(result) {}
+
+  bool Success(const llvm::APSInt &SI, const Expr *E) {
+    assert(E->getType()->isIntegralType() && "Invalid evaluation result.");
+    assert(SI.isSigned() == E->getType()->isSignedIntegerType() &&
+           "Invalid evaluation result.");
+    assert(SI.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) &&
+           "Invalid evaluation result.");
+    Result = APValue(SI);
+    return true;
+  }
+
+  bool Success(const llvm::APInt &I, const Expr *E) {
+    assert(E->getType()->isIntegralType() && "Invalid evaluation result.");
+    assert(I.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) &&
+           "Invalid evaluation result.");
+    Result = APValue(APSInt(I));
+    Result.getInt().setIsUnsigned(E->getType()->isUnsignedIntegerType());
+    return true;
+  }
+
+  bool Success(uint64_t Value, const Expr *E) {
+    assert(E->getType()->isIntegralType() && "Invalid evaluation result.");
+    Result = APValue(Info.Ctx.MakeIntValue(Value, E->getType()));
+    return true;
+  }
+
+  bool Error(SourceLocation L, diag::kind D, const Expr *E) {
+    // Take the first error.
+    if (Info.EvalResult.Diag == 0) {
+      Info.EvalResult.DiagLoc = L;
+      Info.EvalResult.Diag = D;
+      Info.EvalResult.DiagExpr = E;
+    }
+    return false;
+  }
+    
+  //===--------------------------------------------------------------------===//
+  //                            Visitor Methods
+  //===--------------------------------------------------------------------===//
+  
+  bool VisitStmt(Stmt *) {
+    assert(0 && "This should be called on integers, stmts are not integers");
+    return false;
+  }
+    
+  bool VisitExpr(Expr *E) {
+    return Error(E->getLocStart(), diag::note_invalid_subexpr_in_ice, E);
+  }
+  
+  bool VisitParenExpr(ParenExpr *E) { return Visit(E->getSubExpr()); }
+
+  bool VisitIntegerLiteral(const IntegerLiteral *E) {
+    return Success(E->getValue(), E);
+  }
+  bool VisitCharacterLiteral(const CharacterLiteral *E) {
+    return Success(E->getValue(), E);
+  }
+  bool VisitTypesCompatibleExpr(const TypesCompatibleExpr *E) {
+    // Per gcc docs "this built-in function ignores top level
+    // qualifiers".  We need to use the canonical version to properly
+    // be able to strip CRV qualifiers from the type.
+    QualType T0 = Info.Ctx.getCanonicalType(E->getArgType1());
+    QualType T1 = Info.Ctx.getCanonicalType(E->getArgType2());
+    return Success(Info.Ctx.typesAreCompatible(T0.getUnqualifiedType(), 
+                                               T1.getUnqualifiedType()),
+                   E);
+  }
+  bool VisitDeclRefExpr(const DeclRefExpr *E);
+  bool VisitCallExpr(const CallExpr *E);
+  bool VisitBinaryOperator(const BinaryOperator *E);
+  bool VisitUnaryOperator(const UnaryOperator *E);
+  bool VisitConditionalOperator(const ConditionalOperator *E);
+
+  bool VisitCastExpr(CastExpr* E);
+  bool VisitSizeOfAlignOfExpr(const SizeOfAlignOfExpr *E);
+
+  bool VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *E) {
+    return Success(E->getValue(), E);
+  }
+  
+  bool VisitGNUNullExpr(const GNUNullExpr *E) {
+    return Success(0, E);
+  }
+    
+  bool VisitCXXZeroInitValueExpr(const CXXZeroInitValueExpr *E) {
+    return Success(0, E);
+  }
+
+  bool VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) {
+    return Success(0, E);
+  }
+
+  bool VisitUnaryTypeTraitExpr(const UnaryTypeTraitExpr *E) {
+    return Success(E->EvaluateTrait(), E);
+  }
+
+  bool VisitChooseExpr(const ChooseExpr *E) {
+    return Visit(E->getChosenSubExpr(Info.Ctx));
+  }
+
+  bool VisitUnaryReal(const UnaryOperator *E);
+  bool VisitUnaryImag(const UnaryOperator *E);
+
+private:
+  unsigned GetAlignOfExpr(const Expr *E);
+  unsigned GetAlignOfType(QualType T);
+  // FIXME: Missing: array subscript of vector, member of vector
+};
+} // end anonymous namespace
+
+static bool EvaluateIntegerOrLValue(const Expr* E, APValue &Result, EvalInfo &Info) {
+  if (!E->getType()->isIntegralType())
+    return false;
+  
+  return IntExprEvaluator(Info, Result).Visit(const_cast<Expr*>(E));
+}
+
+static bool EvaluateInteger(const Expr* E, APSInt &Result, EvalInfo &Info) {
+  APValue Val;
+  if (!EvaluateIntegerOrLValue(E, Val, Info) || !Val.isInt())
+    return false;
+  Result = Val.getInt();
+  return true;
+}
+
+bool IntExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) {
+  // Enums are integer constant exprs.
+  if (const EnumConstantDecl *D = dyn_cast<EnumConstantDecl>(E->getDecl())) {
+    // FIXME: This is an ugly hack around the fact that enums don't set their
+    // signedness consistently; see PR3173.
+    APSInt SI = D->getInitVal();
+    SI.setIsUnsigned(!E->getType()->isSignedIntegerType());
+    // FIXME: This is an ugly hack around the fact that enums don't
+    // set their width (!?!) consistently; see PR3173.
+    SI.extOrTrunc(Info.Ctx.getIntWidth(E->getType()));
+    return Success(SI, E);
+  }
+
+  // In C++, const, non-volatile integers initialized with ICEs are ICEs.
+  // In C, they can also be folded, although they are not ICEs.
+  if (E->getType().getCVRQualifiers() == QualType::Const) {
+    if (const VarDecl *D = dyn_cast<VarDecl>(E->getDecl())) {
+      if (APValue *V = D->getEvaluatedValue())
+        return Success(V->getInt(), E);
+      if (const Expr *Init = D->getInit()) {
+        if (Visit(const_cast<Expr*>(Init))) {
+          // Cache the evaluated value in the variable declaration.
+          D->setEvaluatedValue(Info.Ctx, Result);
+          return true;
+        }
+
+        return false;
+      }
+    }
+  }
+
+  // Otherwise, random variable references are not constants.
+  return Error(E->getLocStart(), diag::note_invalid_subexpr_in_ice, E);
+}
+
+/// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way
+/// as GCC.
+static int EvaluateBuiltinClassifyType(const CallExpr *E) {
+  // The following enum mimics the values returned by GCC.
+  // FIXME: Does GCC differ between lvalue and rvalue references here?
+  enum gcc_type_class {
+    no_type_class = -1,
+    void_type_class, integer_type_class, char_type_class,
+    enumeral_type_class, boolean_type_class,
+    pointer_type_class, reference_type_class, offset_type_class,
+    real_type_class, complex_type_class,
+    function_type_class, method_type_class,
+    record_type_class, union_type_class,
+    array_type_class, string_type_class,
+    lang_type_class
+  };
+  
+  // If no argument was supplied, default to "no_type_class". This isn't 
+  // ideal, however it is what gcc does.
+  if (E->getNumArgs() == 0)
+    return no_type_class;
+  
+  QualType ArgTy = E->getArg(0)->getType();
+  if (ArgTy->isVoidType())
+    return void_type_class;
+  else if (ArgTy->isEnumeralType())
+    return enumeral_type_class;
+  else if (ArgTy->isBooleanType())
+    return boolean_type_class;
+  else if (ArgTy->isCharType())
+    return string_type_class; // gcc doesn't appear to use char_type_class
+  else if (ArgTy->isIntegerType())
+    return integer_type_class;
+  else if (ArgTy->isPointerType())
+    return pointer_type_class;
+  else if (ArgTy->isReferenceType())
+    return reference_type_class;
+  else if (ArgTy->isRealType())
+    return real_type_class;
+  else if (ArgTy->isComplexType())
+    return complex_type_class;
+  else if (ArgTy->isFunctionType())
+    return function_type_class;
+  else if (ArgTy->isStructureType())
+    return record_type_class;
+  else if (ArgTy->isUnionType())
+    return union_type_class;
+  else if (ArgTy->isArrayType())
+    return array_type_class;
+  else if (ArgTy->isUnionType())
+    return union_type_class;
+  else  // FIXME: offset_type_class, method_type_class, & lang_type_class?
+    assert(0 && "CallExpr::isBuiltinClassifyType(): unimplemented type");
+  return -1;
+}
+
+bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) {
+  switch (E->isBuiltinCall(Info.Ctx)) {
+  default:
+    return Error(E->getLocStart(), diag::note_invalid_subexpr_in_ice, E);
+  case Builtin::BI__builtin_classify_type:
+    return Success(EvaluateBuiltinClassifyType(E), E);
+    
+  case Builtin::BI__builtin_constant_p:
+    // __builtin_constant_p always has one operand: it returns true if that
+    // operand can be folded, false otherwise.
+    return Success(E->getArg(0)->isEvaluatable(Info.Ctx), E);
+  }
+}
+
+bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
+  if (E->getOpcode() == BinaryOperator::Comma) {
+    if (!Visit(E->getRHS()))
+      return false;
+
+    // If we can't evaluate the LHS, it might have side effects;
+    // conservatively mark it.
+    if (!E->getLHS()->isEvaluatable(Info.Ctx))
+      Info.EvalResult.HasSideEffects = true;
+
+    return true;
+  }
+
+  if (E->isLogicalOp()) {
+    // These need to be handled specially because the operands aren't
+    // necessarily integral
+    bool lhsResult, rhsResult;
+    
+    if (HandleConversionToBool(E->getLHS(), lhsResult, Info)) {
+      // We were able to evaluate the LHS, see if we can get away with not
+      // evaluating the RHS: 0 && X -> 0, 1 || X -> 1
+      if (lhsResult == (E->getOpcode() == BinaryOperator::LOr))
+        return Success(lhsResult, E);
+
+      if (HandleConversionToBool(E->getRHS(), rhsResult, Info)) {
+        if (E->getOpcode() == BinaryOperator::LOr)
+          return Success(lhsResult || rhsResult, E);
+        else
+          return Success(lhsResult && rhsResult, E);
+      }
+    } else {
+      if (HandleConversionToBool(E->getRHS(), rhsResult, Info)) {
+        // We can't evaluate the LHS; however, sometimes the result
+        // is determined by the RHS: X && 0 -> 0, X || 1 -> 1.
+        if (rhsResult == (E->getOpcode() == BinaryOperator::LOr) || 
+            !rhsResult == (E->getOpcode() == BinaryOperator::LAnd)) {
+          // Since we weren't able to evaluate the left hand side, it
+          // must have had side effects.
+          Info.EvalResult.HasSideEffects = true;
+
+          return Success(rhsResult, E);
+        }
+      }
+    }
+
+    return false;
+  }
+
+  QualType LHSTy = E->getLHS()->getType();
+  QualType RHSTy = E->getRHS()->getType();
+
+  if (LHSTy->isAnyComplexType()) {
+    assert(RHSTy->isAnyComplexType() && "Invalid comparison");
+    APValue LHS, RHS;
+
+    if (!EvaluateComplex(E->getLHS(), LHS, Info))
+      return false;
+
+    if (!EvaluateComplex(E->getRHS(), RHS, Info))
+      return false;
+
+    if (LHS.isComplexFloat()) {
+      APFloat::cmpResult CR_r = 
+        LHS.getComplexFloatReal().compare(RHS.getComplexFloatReal());
+      APFloat::cmpResult CR_i = 
+        LHS.getComplexFloatImag().compare(RHS.getComplexFloatImag());
+
+      if (E->getOpcode() == BinaryOperator::EQ)
+        return Success((CR_r == APFloat::cmpEqual &&
+                        CR_i == APFloat::cmpEqual), E);
+      else {
+        assert(E->getOpcode() == BinaryOperator::NE &&
+               "Invalid complex comparison.");
+        return Success(((CR_r == APFloat::cmpGreaterThan || 
+                         CR_r == APFloat::cmpLessThan) &&
+                        (CR_i == APFloat::cmpGreaterThan || 
+                         CR_i == APFloat::cmpLessThan)), E);
+      }
+    } else {
+      if (E->getOpcode() == BinaryOperator::EQ)
+        return Success((LHS.getComplexIntReal() == RHS.getComplexIntReal() &&
+                        LHS.getComplexIntImag() == RHS.getComplexIntImag()), E);
+      else {
+        assert(E->getOpcode() == BinaryOperator::NE &&
+               "Invalid compex comparison.");
+        return Success((LHS.getComplexIntReal() != RHS.getComplexIntReal() ||
+                        LHS.getComplexIntImag() != RHS.getComplexIntImag()), E);
+      }
+    }
+  }
+  
+  if (LHSTy->isRealFloatingType() &&
+      RHSTy->isRealFloatingType()) {
+    APFloat RHS(0.0), LHS(0.0);
+    
+    if (!EvaluateFloat(E->getRHS(), RHS, Info))
+      return false;
+    
+    if (!EvaluateFloat(E->getLHS(), LHS, Info))
+      return false;
+    
+    APFloat::cmpResult CR = LHS.compare(RHS);
+
+    switch (E->getOpcode()) {
+    default:
+      assert(0 && "Invalid binary operator!");
+    case BinaryOperator::LT:
+      return Success(CR == APFloat::cmpLessThan, E);
+    case BinaryOperator::GT:
+      return Success(CR == APFloat::cmpGreaterThan, E);
+    case BinaryOperator::LE:
+      return Success(CR == APFloat::cmpLessThan || CR == APFloat::cmpEqual, E);
+    case BinaryOperator::GE:
+      return Success(CR == APFloat::cmpGreaterThan || CR == APFloat::cmpEqual, 
+                     E);
+    case BinaryOperator::EQ:
+      return Success(CR == APFloat::cmpEqual, E);
+    case BinaryOperator::NE:
+      return Success(CR == APFloat::cmpGreaterThan 
+                     || CR == APFloat::cmpLessThan, E);
+    }
+  }
+  
+  if (LHSTy->isPointerType() && RHSTy->isPointerType()) {
+    if (E->getOpcode() == BinaryOperator::Sub || E->isEqualityOp()) {
+      APValue LHSValue;
+      if (!EvaluatePointer(E->getLHS(), LHSValue, Info))
+        return false;
+
+      APValue RHSValue;
+      if (!EvaluatePointer(E->getRHS(), RHSValue, Info))
+        return false;
+
+      // Reject any bases; this is conservative, but good enough for
+      // common uses
+      if (LHSValue.getLValueBase() || RHSValue.getLValueBase())
+        return false;
+
+      if (E->getOpcode() == BinaryOperator::Sub) {
+        const QualType Type = E->getLHS()->getType();
+        const QualType ElementType = Type->getAsPointerType()->getPointeeType();
+
+        uint64_t D = LHSValue.getLValueOffset() - RHSValue.getLValueOffset();
+        D /= Info.Ctx.getTypeSize(ElementType) / 8;
+
+        return Success(D, E);
+      }
+      bool Result;
+      if (E->getOpcode() == BinaryOperator::EQ) {
+        Result = LHSValue.getLValueOffset() == RHSValue.getLValueOffset();
+      } else {
+        Result = LHSValue.getLValueOffset() != RHSValue.getLValueOffset();
+      }
+      return Success(Result, E);
+    }
+  }
+  if (!LHSTy->isIntegralType() ||
+      !RHSTy->isIntegralType()) {
+    // We can't continue from here for non-integral types, and they
+    // could potentially confuse the following operations.
+    return false;
+  }
+
+  // The LHS of a constant expr is always evaluated and needed.
+  if (!Visit(E->getLHS()))
+    return false; // error in subexpression.
+
+  APValue RHSVal;
+  if (!EvaluateIntegerOrLValue(E->getRHS(), RHSVal, Info))
+    return false;
+
+  // Handle cases like (unsigned long)&a + 4.
+  if (E->isAdditiveOp() && Result.isLValue() && RHSVal.isInt()) {
+    uint64_t offset = Result.getLValueOffset();
+    if (E->getOpcode() == BinaryOperator::Add)
+      offset += RHSVal.getInt().getZExtValue();
+    else
+      offset -= RHSVal.getInt().getZExtValue();
+    Result = APValue(Result.getLValueBase(), offset);
+    return true;
+  }
+
+  // Handle cases like 4 + (unsigned long)&a
+  if (E->getOpcode() == BinaryOperator::Add &&
+        RHSVal.isLValue() && Result.isInt()) {
+    uint64_t offset = RHSVal.getLValueOffset();
+    offset += Result.getInt().getZExtValue();
+    Result = APValue(RHSVal.getLValueBase(), offset);
+    return true;
+  }
+
+  // All the following cases expect both operands to be an integer
+  if (!Result.isInt() || !RHSVal.isInt())
+    return false;
+
+  APSInt& RHS = RHSVal.getInt();
+
+  switch (E->getOpcode()) {
+  default:
+    return Error(E->getOperatorLoc(), diag::note_invalid_subexpr_in_ice, E);
+  case BinaryOperator::Mul: return Success(Result.getInt() * RHS, E);
+  case BinaryOperator::Add: return Success(Result.getInt() + RHS, E);
+  case BinaryOperator::Sub: return Success(Result.getInt() - RHS, E);
+  case BinaryOperator::And: return Success(Result.getInt() & RHS, E);
+  case BinaryOperator::Xor: return Success(Result.getInt() ^ RHS, E);
+  case BinaryOperator::Or:  return Success(Result.getInt() | RHS, E);
+  case BinaryOperator::Div:
+    if (RHS == 0)
+      return Error(E->getOperatorLoc(), diag::note_expr_divide_by_zero, E);
+    return Success(Result.getInt() / RHS, E);
+  case BinaryOperator::Rem:
+    if (RHS == 0)
+      return Error(E->getOperatorLoc(), diag::note_expr_divide_by_zero, E);
+    return Success(Result.getInt() % RHS, E);
+  case BinaryOperator::Shl: {
+    // FIXME: Warn about out of range shift amounts!
+    unsigned SA = 
+      (unsigned) RHS.getLimitedValue(Result.getInt().getBitWidth()-1);
+    return Success(Result.getInt() << SA, E);
+  }
+  case BinaryOperator::Shr: {
+    unsigned SA = 
+      (unsigned) RHS.getLimitedValue(Result.getInt().getBitWidth()-1);
+    return Success(Result.getInt() >> SA, E);
+  }
+      
+  case BinaryOperator::LT: return Success(Result.getInt() < RHS, E);
+  case BinaryOperator::GT: return Success(Result.getInt() > RHS, E);
+  case BinaryOperator::LE: return Success(Result.getInt() <= RHS, E);
+  case BinaryOperator::GE: return Success(Result.getInt() >= RHS, E);
+  case BinaryOperator::EQ: return Success(Result.getInt() == RHS, E);
+  case BinaryOperator::NE: return Success(Result.getInt() != RHS, E);
+  }
+}
+
+bool IntExprEvaluator::VisitConditionalOperator(const ConditionalOperator *E) {
+  bool Cond;
+  if (!HandleConversionToBool(E->getCond(), Cond, Info))
+    return false;
+
+  return Visit(Cond ? E->getTrueExpr() : E->getFalseExpr());
+}
+
+unsigned IntExprEvaluator::GetAlignOfType(QualType T) {
+  // Get information about the alignment.
+  unsigned CharSize = Info.Ctx.Target.getCharWidth();
+
+  // __alignof is defined to return the preferred alignment.
+  return Info.Ctx.getPreferredTypeAlign(T.getTypePtr()) / CharSize;
+}
+
+unsigned IntExprEvaluator::GetAlignOfExpr(const Expr *E) {
+  E = E->IgnoreParens();
+
+  // alignof decl is always accepted, even if it doesn't make sense: we default
+  // to 1 in those cases. 
+  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
+    return Info.Ctx.getDeclAlignInBytes(DRE->getDecl());
+
+  if (const MemberExpr *ME = dyn_cast<MemberExpr>(E))
+    return Info.Ctx.getDeclAlignInBytes(ME->getMemberDecl());
+
+  return GetAlignOfType(E->getType());
+}
+
+
+/// VisitSizeAlignOfExpr - Evaluate a sizeof or alignof with a result as the
+/// expression's type.
+bool IntExprEvaluator::VisitSizeOfAlignOfExpr(const SizeOfAlignOfExpr *E) {
+  QualType DstTy = E->getType();
+
+  // Handle alignof separately.
+  if (!E->isSizeOf()) {
+    if (E->isArgumentType())
+      return Success(GetAlignOfType(E->getArgumentType()), E);
+    else
+      return Success(GetAlignOfExpr(E->getArgumentExpr()), E);
+  }
+
+  QualType SrcTy = E->getTypeOfArgument();
+
+  // sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc
+  // extension.
+  if (SrcTy->isVoidType() || SrcTy->isFunctionType())
+    return Success(1, E);
+
+  // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2.
+  if (!SrcTy->isConstantSizeType())
+    return false;
+
+  // Get information about the size.
+  unsigned BitWidth = Info.Ctx.getTypeSize(SrcTy);
+  return Success(BitWidth / Info.Ctx.Target.getCharWidth(), E);
+}
+
+bool IntExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
+  // Special case unary operators that do not need their subexpression
+  // evaluated.  offsetof/sizeof/alignof are all special.
+  if (E->isOffsetOfOp()) {
+    // The AST for offsetof is defined in such a way that we can just
+    // directly Evaluate it as an l-value.
+    APValue LV;
+    if (!EvaluateLValue(E->getSubExpr(), LV, Info))
+      return false;
+    if (LV.getLValueBase())
+      return false;
+    return Success(LV.getLValueOffset(), E);
+  }
+
+  if (E->getOpcode() == UnaryOperator::LNot) {
+    // LNot's operand isn't necessarily an integer, so we handle it specially.
+    bool bres;
+    if (!HandleConversionToBool(E->getSubExpr(), bres, Info))
+      return false;
+    return Success(!bres, E);
+  }
+
+  // Only handle integral operations...
+  if (!E->getSubExpr()->getType()->isIntegralType())
+    return false;
+
+  // Get the operand value into 'Result'.
+  if (!Visit(E->getSubExpr()))
+    return false;
+
+  switch (E->getOpcode()) {
+  default:
+    // Address, indirect, pre/post inc/dec, etc are not valid constant exprs.
+    // See C99 6.6p3.
+    return Error(E->getOperatorLoc(), diag::note_invalid_subexpr_in_ice, E);
+  case UnaryOperator::Extension:
+    // FIXME: Should extension allow i-c-e extension expressions in its scope?
+    // If so, we could clear the diagnostic ID.
+    return true;
+  case UnaryOperator::Plus:
+    // The result is always just the subexpr. 
+    return true;
+  case UnaryOperator::Minus:
+    if (!Result.isInt()) return false;
+    return Success(-Result.getInt(), E);
+  case UnaryOperator::Not:
+    if (!Result.isInt()) return false;
+    return Success(~Result.getInt(), E);
+  }
+}
+  
+/// HandleCast - This is used to evaluate implicit or explicit casts where the
+/// result type is integer.
+bool IntExprEvaluator::VisitCastExpr(CastExpr *E) {
+  Expr *SubExpr = E->getSubExpr();
+  QualType DestType = E->getType();
+  QualType SrcType = SubExpr->getType();
+
+  if (DestType->isBooleanType()) {
+    bool BoolResult;
+    if (!HandleConversionToBool(SubExpr, BoolResult, Info))
+      return false;
+    return Success(BoolResult, E);
+  }
+
+  // Handle simple integer->integer casts.
+  if (SrcType->isIntegralType()) {
+    if (!Visit(SubExpr))
+      return false;
+
+    if (!Result.isInt()) {
+      // Only allow casts of lvalues if they are lossless.
+      return Info.Ctx.getTypeSize(DestType) == Info.Ctx.getTypeSize(SrcType);
+    }
+
+    return Success(HandleIntToIntCast(DestType, SrcType,
+                                      Result.getInt(), Info.Ctx), E);
+  }
+  
+  // FIXME: Clean this up!
+  if (SrcType->isPointerType()) {
+    APValue LV;
+    if (!EvaluatePointer(SubExpr, LV, Info))
+      return false;
+
+    if (LV.getLValueBase()) {
+      // Only allow based lvalue casts if they are lossless.
+      if (Info.Ctx.getTypeSize(DestType) != Info.Ctx.getTypeSize(SrcType))
+        return false;
+
+      Result = LV;
+      return true;
+    }
+
+    APSInt AsInt = Info.Ctx.MakeIntValue(LV.getLValueOffset(), SrcType);
+    return Success(HandleIntToIntCast(DestType, SrcType, AsInt, Info.Ctx), E);
+  }
+
+  if (SrcType->isArrayType() || SrcType->isFunctionType()) {
+    // This handles double-conversion cases, where there's both
+    // an l-value promotion and an implicit conversion to int.
+    APValue LV;
+    if (!EvaluateLValue(SubExpr, LV, Info))
+      return false;
+
+    if (Info.Ctx.getTypeSize(DestType) != Info.Ctx.getTypeSize(Info.Ctx.VoidPtrTy))
+      return false;
+
+    Result = LV;
+    return true;
+  }
+
+  if (SrcType->isAnyComplexType()) {
+    APValue C;
+    if (!EvaluateComplex(SubExpr, C, Info))
+      return false;
+    if (C.isComplexFloat())
+      return Success(HandleFloatToIntCast(DestType, SrcType,
+                                          C.getComplexFloatReal(), Info.Ctx),
+                     E);
+    else
+      return Success(HandleIntToIntCast(DestType, SrcType,
+                                        C.getComplexIntReal(), Info.Ctx), E);
+  }
+  // FIXME: Handle vectors
+
+  if (!SrcType->isRealFloatingType())
+    return Error(E->getExprLoc(), diag::note_invalid_subexpr_in_ice, E);
+
+  APFloat F(0.0);
+  if (!EvaluateFloat(SubExpr, F, Info))
+    return Error(E->getExprLoc(), diag::note_invalid_subexpr_in_ice, E);
+  
+  return Success(HandleFloatToIntCast(DestType, SrcType, F, Info.Ctx), E);
+}
+
+bool IntExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
+  if (E->getSubExpr()->getType()->isAnyComplexType()) {
+    APValue LV;
+    if (!EvaluateComplex(E->getSubExpr(), LV, Info) || !LV.isComplexInt())
+      return Error(E->getExprLoc(), diag::note_invalid_subexpr_in_ice, E);
+    return Success(LV.getComplexIntReal(), E);
+  }
+
+  return Visit(E->getSubExpr());
+}
+
+bool IntExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
+  if (E->getSubExpr()->getType()->isComplexIntegerType()) {
+    APValue LV;
+    if (!EvaluateComplex(E->getSubExpr(), LV, Info) || !LV.isComplexInt())
+      return Error(E->getExprLoc(), diag::note_invalid_subexpr_in_ice, E);
+    return Success(LV.getComplexIntImag(), E);
+  }
+
+  if (!E->getSubExpr()->isEvaluatable(Info.Ctx))
+    Info.EvalResult.HasSideEffects = true;
+  return Success(0, E);
+}
+
+//===----------------------------------------------------------------------===//
+// Float Evaluation
+//===----------------------------------------------------------------------===//
+
+namespace {
+class VISIBILITY_HIDDEN FloatExprEvaluator
+  : public StmtVisitor<FloatExprEvaluator, bool> {
+  EvalInfo &Info;
+  APFloat &Result;
+public:
+  FloatExprEvaluator(EvalInfo &info, APFloat &result)
+    : Info(info), Result(result) {}
+
+  bool VisitStmt(Stmt *S) {
+    return false;
+  }
+
+  bool VisitParenExpr(ParenExpr *E) { return Visit(E->getSubExpr()); }
+  bool VisitCallExpr(const CallExpr *E);
+
+  bool VisitUnaryOperator(const UnaryOperator *E);
+  bool VisitBinaryOperator(const BinaryOperator *E);
+  bool VisitFloatingLiteral(const FloatingLiteral *E);
+  bool VisitCastExpr(CastExpr *E);
+  bool VisitCXXZeroInitValueExpr(CXXZeroInitValueExpr *E);
+
+  bool VisitChooseExpr(const ChooseExpr *E)
+    { return Visit(E->getChosenSubExpr(Info.Ctx)); }
+  bool VisitUnaryExtension(const UnaryOperator *E)
+    { return Visit(E->getSubExpr()); }
+
+  // FIXME: Missing: __real__/__imag__, array subscript of vector,
+  //                 member of vector, ImplicitValueInitExpr,
+  //                 conditional ?:, comma
+};
+} // end anonymous namespace
+
+static bool EvaluateFloat(const Expr* E, APFloat& Result, EvalInfo &Info) {
+  return FloatExprEvaluator(Info, Result).Visit(const_cast<Expr*>(E));
+}
+
+bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) {
+  switch (E->isBuiltinCall(Info.Ctx)) {
+  default: return false;
+  case Builtin::BI__builtin_huge_val:
+  case Builtin::BI__builtin_huge_valf:
+  case Builtin::BI__builtin_huge_vall:
+  case Builtin::BI__builtin_inf:
+  case Builtin::BI__builtin_inff:
+  case Builtin::BI__builtin_infl: {
+    const llvm::fltSemantics &Sem =
+      Info.Ctx.getFloatTypeSemantics(E->getType());
+    Result = llvm::APFloat::getInf(Sem);
+    return true;
+  }
+      
+  case Builtin::BI__builtin_nan:
+  case Builtin::BI__builtin_nanf:
+  case Builtin::BI__builtin_nanl:
+    // If this is __builtin_nan() turn this into a nan, otherwise we
+    // can't constant fold it.
+    if (const StringLiteral *S = 
+        dyn_cast<StringLiteral>(E->getArg(0)->IgnoreParenCasts())) {
+      if (!S->isWide()) {
+        const llvm::fltSemantics &Sem =
+          Info.Ctx.getFloatTypeSemantics(E->getType());
+        llvm::SmallString<16> s;
+        s.append(S->getStrData(), S->getStrData() + S->getByteLength());
+        s += '\0';
+        long l;
+        char *endp;
+        l = strtol(&s[0], &endp, 0);
+        if (endp != s.end()-1)
+          return false;
+        unsigned type = (unsigned int)l;;
+        Result = llvm::APFloat::getNaN(Sem, false, type);
+        return true;
+      }
+    }
+    return false;
+
+  case Builtin::BI__builtin_fabs:
+  case Builtin::BI__builtin_fabsf:
+  case Builtin::BI__builtin_fabsl:
+    if (!EvaluateFloat(E->getArg(0), Result, Info))
+      return false;
+    
+    if (Result.isNegative())
+      Result.changeSign();
+    return true;
+
+  case Builtin::BI__builtin_copysign: 
+  case Builtin::BI__builtin_copysignf: 
+  case Builtin::BI__builtin_copysignl: {
+    APFloat RHS(0.);
+    if (!EvaluateFloat(E->getArg(0), Result, Info) ||
+        !EvaluateFloat(E->getArg(1), RHS, Info))
+      return false;
+    Result.copySign(RHS);
+    return true;
+  }
+  }
+}
+
+bool FloatExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
+  if (E->getOpcode() == UnaryOperator::Deref)
+    return false;
+
+  if (!EvaluateFloat(E->getSubExpr(), Result, Info))
+    return false;
+
+  switch (E->getOpcode()) {
+  default: return false;
+  case UnaryOperator::Plus: 
+    return true;
+  case UnaryOperator::Minus:
+    Result.changeSign();
+    return true;
+  }
+}
+
+bool FloatExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
+  // FIXME: Diagnostics?  I really don't understand how the warnings
+  // and errors are supposed to work.
+  APFloat RHS(0.0);
+  if (!EvaluateFloat(E->getLHS(), Result, Info))
+    return false;
+  if (!EvaluateFloat(E->getRHS(), RHS, Info))
+    return false;
+
+  switch (E->getOpcode()) {
+  default: return false;
+  case BinaryOperator::Mul:
+    Result.multiply(RHS, APFloat::rmNearestTiesToEven);
+    return true;
+  case BinaryOperator::Add:
+    Result.add(RHS, APFloat::rmNearestTiesToEven);
+    return true;
+  case BinaryOperator::Sub:
+    Result.subtract(RHS, APFloat::rmNearestTiesToEven);
+    return true;
+  case BinaryOperator::Div:
+    Result.divide(RHS, APFloat::rmNearestTiesToEven);
+    return true;
+  }
+}
+
+bool FloatExprEvaluator::VisitFloatingLiteral(const FloatingLiteral *E) {
+  Result = E->getValue();
+  return true;
+}
+
+bool FloatExprEvaluator::VisitCastExpr(CastExpr *E) {
+  Expr* SubExpr = E->getSubExpr();
+  
+  if (SubExpr->getType()->isIntegralType()) {
+    APSInt IntResult;
+    if (!EvaluateInteger(SubExpr, IntResult, Info))
+      return false;
+    Result = HandleIntToFloatCast(E->getType(), SubExpr->getType(), 
+                                  IntResult, Info.Ctx);
+    return true;
+  }
+  if (SubExpr->getType()->isRealFloatingType()) {
+    if (!Visit(SubExpr))
+      return false;
+    Result = HandleFloatToFloatCast(E->getType(), SubExpr->getType(),
+                                    Result, Info.Ctx);
+    return true;
+  }
+  // FIXME: Handle complex types
+
+  return false;
+}
+
+bool FloatExprEvaluator::VisitCXXZeroInitValueExpr(CXXZeroInitValueExpr *E) {
+  Result = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(E->getType()));
+  return true;
+}
+
+//===----------------------------------------------------------------------===//
+// Complex Evaluation (for float and integer)
+//===----------------------------------------------------------------------===//
+
+namespace {
+class VISIBILITY_HIDDEN ComplexExprEvaluator
+  : public StmtVisitor<ComplexExprEvaluator, APValue> {
+  EvalInfo &Info;
+  
+public:
+  ComplexExprEvaluator(EvalInfo &info) : Info(info) {}
+  
+  //===--------------------------------------------------------------------===//
+  //                            Visitor Methods
+  //===--------------------------------------------------------------------===//
+
+  APValue VisitStmt(Stmt *S) {
+    return APValue();
+  }
+    
+  APValue VisitParenExpr(ParenExpr *E) { return Visit(E->getSubExpr()); }
+
+  APValue VisitImaginaryLiteral(ImaginaryLiteral *E) {
+    Expr* SubExpr = E->getSubExpr();
+
+    if (SubExpr->getType()->isRealFloatingType()) {
+      APFloat Result(0.0);
+
+      if (!EvaluateFloat(SubExpr, Result, Info))
+        return APValue();
+    
+      return APValue(APFloat(Result.getSemantics(), APFloat::fcZero, false), 
+                     Result);
+    } else {
+      assert(SubExpr->getType()->isIntegerType() && 
+             "Unexpected imaginary literal.");
+
+      llvm::APSInt Result;
+      if (!EvaluateInteger(SubExpr, Result, Info))
+        return APValue();
+      
+      llvm::APSInt Zero(Result.getBitWidth(), !Result.isSigned());
+      Zero = 0;
+      return APValue(Zero, Result);
+    }
+  }
+
+  APValue VisitCastExpr(CastExpr *E) {
+    Expr* SubExpr = E->getSubExpr();
+    QualType EltType = E->getType()->getAsComplexType()->getElementType();
+    QualType SubType = SubExpr->getType();
+
+    if (SubType->isRealFloatingType()) {
+      APFloat Result(0.0);
+
+      if (!EvaluateFloat(SubExpr, Result, Info))
+        return APValue();
+
+      if (EltType->isRealFloatingType()) {
+        Result = HandleFloatToFloatCast(EltType, SubType, Result, Info.Ctx);
+        return APValue(Result, 
+                       APFloat(Result.getSemantics(), APFloat::fcZero, false));
+      } else {
+        llvm::APSInt IResult;
+        IResult = HandleFloatToIntCast(EltType, SubType, Result, Info.Ctx);
+        llvm::APSInt Zero(IResult.getBitWidth(), !IResult.isSigned());
+        Zero = 0;
+        return APValue(IResult, Zero);
+      }
+    } else if (SubType->isIntegerType()) {
+      APSInt Result;
+
+      if (!EvaluateInteger(SubExpr, Result, Info))
+        return APValue();
+
+      if (EltType->isRealFloatingType()) {
+        APFloat FResult =
+            HandleIntToFloatCast(EltType, SubType, Result, Info.Ctx);
+        return APValue(FResult, 
+                       APFloat(FResult.getSemantics(), APFloat::fcZero, false));
+      } else {
+        Result = HandleIntToIntCast(EltType, SubType, Result, Info.Ctx);
+        llvm::APSInt Zero(Result.getBitWidth(), !Result.isSigned());
+        Zero = 0;
+        return APValue(Result, Zero);
+      }
+    } else if (const ComplexType *CT = SubType->getAsComplexType()) {
+      APValue Src;
+
+      if (!EvaluateComplex(SubExpr, Src, Info))
+        return APValue();
+
+      QualType SrcType = CT->getElementType();
+
+      if (Src.isComplexFloat()) {
+        if (EltType->isRealFloatingType()) {
+          return APValue(HandleFloatToFloatCast(EltType, SrcType, 
+                                                Src.getComplexFloatReal(),
+                                                Info.Ctx),
+                         HandleFloatToFloatCast(EltType, SrcType, 
+                                                Src.getComplexFloatImag(),
+                                                Info.Ctx));
+        } else {
+          return APValue(HandleFloatToIntCast(EltType, SrcType,
+                                              Src.getComplexFloatReal(),
+                                              Info.Ctx),
+                         HandleFloatToIntCast(EltType, SrcType, 
+                                              Src.getComplexFloatImag(),
+                                              Info.Ctx)); 
+        }
+      } else {
+        assert(Src.isComplexInt() && "Invalid evaluate result.");
+        if (EltType->isRealFloatingType()) {
+          return APValue(HandleIntToFloatCast(EltType, SrcType, 
+                                              Src.getComplexIntReal(),
+                                              Info.Ctx),
+                         HandleIntToFloatCast(EltType, SrcType, 
+                                              Src.getComplexIntImag(),
+                                              Info.Ctx));
+        } else {
+          return APValue(HandleIntToIntCast(EltType, SrcType,
+                                            Src.getComplexIntReal(),
+                                            Info.Ctx),
+                         HandleIntToIntCast(EltType, SrcType, 
+                                            Src.getComplexIntImag(),
+                                            Info.Ctx)); 
+        }
+      }
+    }
+
+    // FIXME: Handle more casts.
+    return APValue();
+  }
+  
+  APValue VisitBinaryOperator(const BinaryOperator *E);
+  APValue VisitChooseExpr(const ChooseExpr *E)
+    { return Visit(E->getChosenSubExpr(Info.Ctx)); }
+  APValue VisitUnaryExtension(const UnaryOperator *E)
+    { return Visit(E->getSubExpr()); }
+  // FIXME Missing: unary +/-/~, binary div, ImplicitValueInitExpr,
+  //                conditional ?:, comma
+};
+} // end anonymous namespace
+
+static bool EvaluateComplex(const Expr *E, APValue &Result, EvalInfo &Info)
+{
+  Result = ComplexExprEvaluator(Info).Visit(const_cast<Expr*>(E));
+  assert((!Result.isComplexFloat() ||
+          (&Result.getComplexFloatReal().getSemantics() == 
+           &Result.getComplexFloatImag().getSemantics())) && 
+         "Invalid complex evaluation.");
+  return Result.isComplexFloat() || Result.isComplexInt();
+}
+
+APValue ComplexExprEvaluator::VisitBinaryOperator(const BinaryOperator *E)
+{
+  APValue Result, RHS;
+  
+  if (!EvaluateComplex(E->getLHS(), Result, Info))
+    return APValue();
+  
+  if (!EvaluateComplex(E->getRHS(), RHS, Info))
+    return APValue();
+
+  assert(Result.isComplexFloat() == RHS.isComplexFloat() &&
+         "Invalid operands to binary operator.");
+  switch (E->getOpcode()) {
+  default: return APValue();
+  case BinaryOperator::Add:
+    if (Result.isComplexFloat()) {
+      Result.getComplexFloatReal().add(RHS.getComplexFloatReal(),
+                                       APFloat::rmNearestTiesToEven);
+      Result.getComplexFloatImag().add(RHS.getComplexFloatImag(),
+                                       APFloat::rmNearestTiesToEven);
+    } else {
+      Result.getComplexIntReal() += RHS.getComplexIntReal();
+      Result.getComplexIntImag() += RHS.getComplexIntImag();
+    }
+    break;
+  case BinaryOperator::Sub:
+    if (Result.isComplexFloat()) {
+      Result.getComplexFloatReal().subtract(RHS.getComplexFloatReal(),
+                                            APFloat::rmNearestTiesToEven);
+      Result.getComplexFloatImag().subtract(RHS.getComplexFloatImag(),
+                                            APFloat::rmNearestTiesToEven);
+    } else {
+      Result.getComplexIntReal() -= RHS.getComplexIntReal();
+      Result.getComplexIntImag() -= RHS.getComplexIntImag();
+    }
+    break;
+  case BinaryOperator::Mul:
+    if (Result.isComplexFloat()) {
+      APValue LHS = Result;
+      APFloat &LHS_r = LHS.getComplexFloatReal();
+      APFloat &LHS_i = LHS.getComplexFloatImag();
+      APFloat &RHS_r = RHS.getComplexFloatReal();
+      APFloat &RHS_i = RHS.getComplexFloatImag();
+      
+      APFloat Tmp = LHS_r;
+      Tmp.multiply(RHS_r, APFloat::rmNearestTiesToEven);
+      Result.getComplexFloatReal() = Tmp;
+      Tmp = LHS_i;
+      Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven);
+      Result.getComplexFloatReal().subtract(Tmp, APFloat::rmNearestTiesToEven);
+
+      Tmp = LHS_r;
+      Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven);
+      Result.getComplexFloatImag() = Tmp;
+      Tmp = LHS_i;
+      Tmp.multiply(RHS_r, APFloat::rmNearestTiesToEven);
+      Result.getComplexFloatImag().add(Tmp, APFloat::rmNearestTiesToEven);
+    } else {
+      APValue LHS = Result;
+      Result.getComplexIntReal() = 
+        (LHS.getComplexIntReal() * RHS.getComplexIntReal() -
+         LHS.getComplexIntImag() * RHS.getComplexIntImag());
+      Result.getComplexIntImag() = 
+        (LHS.getComplexIntReal() * RHS.getComplexIntImag() +
+         LHS.getComplexIntImag() * RHS.getComplexIntReal());
+    }
+    break;
+  }
+
+  return Result;
+}
+
+//===----------------------------------------------------------------------===//
+// Top level Expr::Evaluate method.
+//===----------------------------------------------------------------------===//
+
+/// Evaluate - Return true if this is a constant which we can fold using
+/// any crazy technique (that has nothing to do with language standards) that
+/// we want to.  If this function returns true, it returns the folded constant
+/// in Result.
+bool Expr::Evaluate(EvalResult &Result, ASTContext &Ctx) const {
+  EvalInfo Info(Ctx, Result);
+
+  if (getType()->isVectorType()) {
+    if (!EvaluateVector(this, Result.Val, Info))
+      return false;
+  } else if (getType()->isIntegerType()) {
+    if (!IntExprEvaluator(Info, Result.Val).Visit(const_cast<Expr*>(this)))
+      return false;
+  } else if (getType()->hasPointerRepresentation()) {
+    if (!EvaluatePointer(this, Result.Val, Info))
+      return false;
+  } else if (getType()->isRealFloatingType()) {
+    llvm::APFloat f(0.0);
+    if (!EvaluateFloat(this, f, Info))
+      return false;
+    
+    Result.Val = APValue(f);
+  } else if (getType()->isAnyComplexType()) {
+    if (!EvaluateComplex(this, Result.Val, Info))
+      return false;
+  } else
+    return false;
+
+  return true;
+}
+
+bool Expr::EvaluateAsLValue(EvalResult &Result, ASTContext &Ctx) const {
+  EvalInfo Info(Ctx, Result);
+
+  return EvaluateLValue(this, Result.Val, Info) && !Result.HasSideEffects;
+}
+
+/// isEvaluatable - Call Evaluate to see if this expression can be constant
+/// folded, but discard the result.
+bool Expr::isEvaluatable(ASTContext &Ctx) const {
+  EvalResult Result;
+  return Evaluate(Result, Ctx) && !Result.HasSideEffects;
+}
+
+APSInt Expr::EvaluateAsInt(ASTContext &Ctx) const {
+  EvalResult EvalResult;
+  bool Result = Evaluate(EvalResult, Ctx);
+  Result = Result;
+  assert(Result && "Could not evaluate expression");
+  assert(EvalResult.Val.isInt() && "Expression did not evaluate to integer");
+
+  return EvalResult.Val.getInt();
+}