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

1 files changed, 5153 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
new file mode 100644
index 0000000..0d15ce2
--- /dev/null
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -0,0 +1,5153 @@
+//===--- SemaChecking.cpp - Extra Semantic Checking -----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file implements extra semantic analysis beyond what is enforced
+//  by the C type system.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Sema/Initialization.h"
+#include "clang/Sema/Sema.h"
+#include "clang/Sema/SemaInternal.h"
+#include "clang/Sema/Initialization.h"
+#include "clang/Sema/ScopeInfo.h"
+#include "clang/Analysis/Analyses/FormatString.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/CharUnits.h"
+#include "clang/AST/DeclCXX.h"
+#include "clang/AST/DeclObjC.h"
+#include "clang/AST/ExprCXX.h"
+#include "clang/AST/ExprObjC.h"
+#include "clang/AST/EvaluatedExprVisitor.h"
+#include "clang/AST/DeclObjC.h"
+#include "clang/AST/StmtCXX.h"
+#include "clang/AST/StmtObjC.h"
+#include "clang/Lex/Preprocessor.h"
+#include "llvm/ADT/BitVector.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Support/raw_ostream.h"
+#include "clang/Basic/TargetBuiltins.h"
+#include "clang/Basic/TargetInfo.h"
+#include "clang/Basic/ConvertUTF.h"
+#include <limits>
+using namespace clang;
+using namespace sema;
+
+SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL,
+                                                    unsigned ByteNo) const {
+  return SL->getLocationOfByte(ByteNo, PP.getSourceManager(),
+                               PP.getLangOpts(), PP.getTargetInfo());
+}
+
+/// Checks that a call expression's argument count is the desired number.
+/// This is useful when doing custom type-checking.  Returns true on error.
+static bool checkArgCount(Sema &S, CallExpr *call, unsigned desiredArgCount) {
+  unsigned argCount = call->getNumArgs();
+  if (argCount == desiredArgCount) return false;
+
+  if (argCount < desiredArgCount)
+    return S.Diag(call->getLocEnd(), diag::err_typecheck_call_too_few_args)
+        << 0 /*function call*/ << desiredArgCount << argCount
+        << call->getSourceRange();
+
+  // Highlight all the excess arguments.
+  SourceRange range(call->getArg(desiredArgCount)->getLocStart(),
+                    call->getArg(argCount - 1)->getLocEnd());
+    
+  return S.Diag(range.getBegin(), diag::err_typecheck_call_too_many_args)
+    << 0 /*function call*/ << desiredArgCount << argCount
+    << call->getArg(1)->getSourceRange();
+}
+
+/// CheckBuiltinAnnotationString - Checks that string argument to the builtin
+/// annotation is a non wide string literal.
+static bool CheckBuiltinAnnotationString(Sema &S, Expr *Arg) {
+  Arg = Arg->IgnoreParenCasts();
+  StringLiteral *Literal = dyn_cast<StringLiteral>(Arg);
+  if (!Literal || !Literal->isAscii()) {
+    S.Diag(Arg->getLocStart(), diag::err_builtin_annotation_not_string_constant)
+      << Arg->getSourceRange();
+    return true;
+  }
+  return false;
+}
+
+ExprResult
+Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
+  ExprResult TheCallResult(Owned(TheCall));
+
+  // Find out if any arguments are required to be integer constant expressions.
+  unsigned ICEArguments = 0;
+  ASTContext::GetBuiltinTypeError Error;
+  Context.GetBuiltinType(BuiltinID, Error, &ICEArguments);
+  if (Error != ASTContext::GE_None)
+    ICEArguments = 0;  // Don't diagnose previously diagnosed errors.
+  
+  // If any arguments are required to be ICE's, check and diagnose.
+  for (unsigned ArgNo = 0; ICEArguments != 0; ++ArgNo) {
+    // Skip arguments not required to be ICE's.
+    if ((ICEArguments & (1 << ArgNo)) == 0) continue;
+    
+    llvm::APSInt Result;
+    if (SemaBuiltinConstantArg(TheCall, ArgNo, Result))
+      return true;
+    ICEArguments &= ~(1 << ArgNo);
+  }
+  
+  switch (BuiltinID) {
+  case Builtin::BI__builtin___CFStringMakeConstantString:
+    assert(TheCall->getNumArgs() == 1 &&
+           "Wrong # arguments to builtin CFStringMakeConstantString");
+    if (CheckObjCString(TheCall->getArg(0)))
+      return ExprError();
+    break;
+  case Builtin::BI__builtin_stdarg_start:
+  case Builtin::BI__builtin_va_start:
+    if (SemaBuiltinVAStart(TheCall))
+      return ExprError();
+    break;
+  case Builtin::BI__builtin_isgreater:
+  case Builtin::BI__builtin_isgreaterequal:
+  case Builtin::BI__builtin_isless:
+  case Builtin::BI__builtin_islessequal:
+  case Builtin::BI__builtin_islessgreater:
+  case Builtin::BI__builtin_isunordered:
+    if (SemaBuiltinUnorderedCompare(TheCall))
+      return ExprError();
+    break;
+  case Builtin::BI__builtin_fpclassify:
+    if (SemaBuiltinFPClassification(TheCall, 6))
+      return ExprError();
+    break;
+  case Builtin::BI__builtin_isfinite:
+  case Builtin::BI__builtin_isinf:
+  case Builtin::BI__builtin_isinf_sign:
+  case Builtin::BI__builtin_isnan:
+  case Builtin::BI__builtin_isnormal:
+    if (SemaBuiltinFPClassification(TheCall, 1))
+      return ExprError();
+    break;
+  case Builtin::BI__builtin_shufflevector:
+    return SemaBuiltinShuffleVector(TheCall);
+    // TheCall will be freed by the smart pointer here, but that's fine, since
+    // SemaBuiltinShuffleVector guts it, but then doesn't release it.
+  case Builtin::BI__builtin_prefetch:
+    if (SemaBuiltinPrefetch(TheCall))
+      return ExprError();
+    break;
+  case Builtin::BI__builtin_object_size:
+    if (SemaBuiltinObjectSize(TheCall))
+      return ExprError();
+    break;
+  case Builtin::BI__builtin_longjmp:
+    if (SemaBuiltinLongjmp(TheCall))
+      return ExprError();
+    break;
+
+  case Builtin::BI__builtin_classify_type:
+    if (checkArgCount(*this, TheCall, 1)) return true;
+    TheCall->setType(Context.IntTy);
+    break;
+  case Builtin::BI__builtin_constant_p:
+    if (checkArgCount(*this, TheCall, 1)) return true;
+    TheCall->setType(Context.IntTy);
+    break;
+  case Builtin::BI__sync_fetch_and_add:
+  case Builtin::BI__sync_fetch_and_add_1:
+  case Builtin::BI__sync_fetch_and_add_2:
+  case Builtin::BI__sync_fetch_and_add_4:
+  case Builtin::BI__sync_fetch_and_add_8:
+  case Builtin::BI__sync_fetch_and_add_16:
+  case Builtin::BI__sync_fetch_and_sub:
+  case Builtin::BI__sync_fetch_and_sub_1:
+  case Builtin::BI__sync_fetch_and_sub_2:
+  case Builtin::BI__sync_fetch_and_sub_4:
+  case Builtin::BI__sync_fetch_and_sub_8:
+  case Builtin::BI__sync_fetch_and_sub_16:
+  case Builtin::BI__sync_fetch_and_or:
+  case Builtin::BI__sync_fetch_and_or_1:
+  case Builtin::BI__sync_fetch_and_or_2:
+  case Builtin::BI__sync_fetch_and_or_4:
+  case Builtin::BI__sync_fetch_and_or_8:
+  case Builtin::BI__sync_fetch_and_or_16:
+  case Builtin::BI__sync_fetch_and_and:
+  case Builtin::BI__sync_fetch_and_and_1:
+  case Builtin::BI__sync_fetch_and_and_2:
+  case Builtin::BI__sync_fetch_and_and_4:
+  case Builtin::BI__sync_fetch_and_and_8:
+  case Builtin::BI__sync_fetch_and_and_16:
+  case Builtin::BI__sync_fetch_and_xor:
+  case Builtin::BI__sync_fetch_and_xor_1:
+  case Builtin::BI__sync_fetch_and_xor_2:
+  case Builtin::BI__sync_fetch_and_xor_4:
+  case Builtin::BI__sync_fetch_and_xor_8:
+  case Builtin::BI__sync_fetch_and_xor_16:
+  case Builtin::BI__sync_add_and_fetch:
+  case Builtin::BI__sync_add_and_fetch_1:
+  case Builtin::BI__sync_add_and_fetch_2:
+  case Builtin::BI__sync_add_and_fetch_4:
+  case Builtin::BI__sync_add_and_fetch_8:
+  case Builtin::BI__sync_add_and_fetch_16:
+  case Builtin::BI__sync_sub_and_fetch:
+  case Builtin::BI__sync_sub_and_fetch_1:
+  case Builtin::BI__sync_sub_and_fetch_2:
+  case Builtin::BI__sync_sub_and_fetch_4:
+  case Builtin::BI__sync_sub_and_fetch_8:
+  case Builtin::BI__sync_sub_and_fetch_16:
+  case Builtin::BI__sync_and_and_fetch:
+  case Builtin::BI__sync_and_and_fetch_1:
+  case Builtin::BI__sync_and_and_fetch_2:
+  case Builtin::BI__sync_and_and_fetch_4:
+  case Builtin::BI__sync_and_and_fetch_8:
+  case Builtin::BI__sync_and_and_fetch_16:
+  case Builtin::BI__sync_or_and_fetch:
+  case Builtin::BI__sync_or_and_fetch_1:
+  case Builtin::BI__sync_or_and_fetch_2:
+  case Builtin::BI__sync_or_and_fetch_4:
+  case Builtin::BI__sync_or_and_fetch_8:
+  case Builtin::BI__sync_or_and_fetch_16:
+  case Builtin::BI__sync_xor_and_fetch:
+  case Builtin::BI__sync_xor_and_fetch_1:
+  case Builtin::BI__sync_xor_and_fetch_2:
+  case Builtin::BI__sync_xor_and_fetch_4:
+  case Builtin::BI__sync_xor_and_fetch_8:
+  case Builtin::BI__sync_xor_and_fetch_16:
+  case Builtin::BI__sync_val_compare_and_swap:
+  case Builtin::BI__sync_val_compare_and_swap_1:
+  case Builtin::BI__sync_val_compare_and_swap_2:
+  case Builtin::BI__sync_val_compare_and_swap_4:
+  case Builtin::BI__sync_val_compare_and_swap_8:
+  case Builtin::BI__sync_val_compare_and_swap_16:
+  case Builtin::BI__sync_bool_compare_and_swap:
+  case Builtin::BI__sync_bool_compare_and_swap_1:
+  case Builtin::BI__sync_bool_compare_and_swap_2:
+  case Builtin::BI__sync_bool_compare_and_swap_4:
+  case Builtin::BI__sync_bool_compare_and_swap_8:
+  case Builtin::BI__sync_bool_compare_and_swap_16:
+  case Builtin::BI__sync_lock_test_and_set:
+  case Builtin::BI__sync_lock_test_and_set_1:
+  case Builtin::BI__sync_lock_test_and_set_2:
+  case Builtin::BI__sync_lock_test_and_set_4:
+  case Builtin::BI__sync_lock_test_and_set_8:
+  case Builtin::BI__sync_lock_test_and_set_16:
+  case Builtin::BI__sync_lock_release:
+  case Builtin::BI__sync_lock_release_1:
+  case Builtin::BI__sync_lock_release_2:
+  case Builtin::BI__sync_lock_release_4:
+  case Builtin::BI__sync_lock_release_8:
+  case Builtin::BI__sync_lock_release_16:
+  case Builtin::BI__sync_swap:
+  case Builtin::BI__sync_swap_1:
+  case Builtin::BI__sync_swap_2:
+  case Builtin::BI__sync_swap_4:
+  case Builtin::BI__sync_swap_8:
+  case Builtin::BI__sync_swap_16:
+    return SemaBuiltinAtomicOverloaded(move(TheCallResult));
+#define BUILTIN(ID, TYPE, ATTRS)
+#define ATOMIC_BUILTIN(ID, TYPE, ATTRS) \
+  case Builtin::BI##ID: \
+    return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::AO##ID);
+#include "clang/Basic/Builtins.def"
+  case Builtin::BI__builtin_annotation:
+    if (CheckBuiltinAnnotationString(*this, TheCall->getArg(1)))
+      return ExprError();
+    break;
+  }
+  
+  // Since the target specific builtins for each arch overlap, only check those
+  // of the arch we are compiling for.
+  if (BuiltinID >= Builtin::FirstTSBuiltin) {
+    switch (Context.getTargetInfo().getTriple().getArch()) {
+      case llvm::Triple::arm:
+      case llvm::Triple::thumb:
+        if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall))
+          return ExprError();
+        break;
+      default:
+        break;
+    }
+  }
+
+  return move(TheCallResult);
+}
+
+// Get the valid immediate range for the specified NEON type code.
+static unsigned RFT(unsigned t, bool shift = false) {
+  NeonTypeFlags Type(t);
+  int IsQuad = Type.isQuad();
+  switch (Type.getEltType()) {
+  case NeonTypeFlags::Int8:
+  case NeonTypeFlags::Poly8:
+    return shift ? 7 : (8 << IsQuad) - 1;
+  case NeonTypeFlags::Int16:
+  case NeonTypeFlags::Poly16:
+    return shift ? 15 : (4 << IsQuad) - 1;
+  case NeonTypeFlags::Int32:
+    return shift ? 31 : (2 << IsQuad) - 1;
+  case NeonTypeFlags::Int64:
+    return shift ? 63 : (1 << IsQuad) - 1;
+  case NeonTypeFlags::Float16:
+    assert(!shift && "cannot shift float types!");
+    return (4 << IsQuad) - 1;
+  case NeonTypeFlags::Float32:
+    assert(!shift && "cannot shift float types!");
+    return (2 << IsQuad) - 1;
+  }
+  llvm_unreachable("Invalid NeonTypeFlag!");
+}
+
+/// getNeonEltType - Return the QualType corresponding to the elements of
+/// the vector type specified by the NeonTypeFlags.  This is used to check
+/// the pointer arguments for Neon load/store intrinsics.
+static QualType getNeonEltType(NeonTypeFlags Flags, ASTContext &Context) {
+  switch (Flags.getEltType()) {
+  case NeonTypeFlags::Int8:
+    return Flags.isUnsigned() ? Context.UnsignedCharTy : Context.SignedCharTy;
+  case NeonTypeFlags::Int16:
+    return Flags.isUnsigned() ? Context.UnsignedShortTy : Context.ShortTy;
+  case NeonTypeFlags::Int32:
+    return Flags.isUnsigned() ? Context.UnsignedIntTy : Context.IntTy;
+  case NeonTypeFlags::Int64:
+    return Flags.isUnsigned() ? Context.UnsignedLongLongTy : Context.LongLongTy;
+  case NeonTypeFlags::Poly8:
+    return Context.SignedCharTy;
+  case NeonTypeFlags::Poly16:
+    return Context.ShortTy;
+  case NeonTypeFlags::Float16:
+    return Context.UnsignedShortTy;
+  case NeonTypeFlags::Float32:
+    return Context.FloatTy;
+  }
+  llvm_unreachable("Invalid NeonTypeFlag!");
+}
+
+bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
+  llvm::APSInt Result;
+
+  unsigned mask = 0;
+  unsigned TV = 0;
+  int PtrArgNum = -1;
+  bool HasConstPtr = false;
+  switch (BuiltinID) {
+#define GET_NEON_OVERLOAD_CHECK
+#include "clang/Basic/arm_neon.inc"
+#undef GET_NEON_OVERLOAD_CHECK
+  }
+  
+  // For NEON intrinsics which are overloaded on vector element type, validate
+  // the immediate which specifies which variant to emit.
+  unsigned ImmArg = TheCall->getNumArgs()-1;
+  if (mask) {
+    if (SemaBuiltinConstantArg(TheCall, ImmArg, Result))
+      return true;
+    
+    TV = Result.getLimitedValue(64);
+    if ((TV > 63) || (mask & (1 << TV)) == 0)
+      return Diag(TheCall->getLocStart(), diag::err_invalid_neon_type_code)
+        << TheCall->getArg(ImmArg)->getSourceRange();
+  }
+
+  if (PtrArgNum >= 0) {
+    // Check that pointer arguments have the specified type.
+    Expr *Arg = TheCall->getArg(PtrArgNum);
+    if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg))
+      Arg = ICE->getSubExpr();
+    ExprResult RHS = DefaultFunctionArrayLvalueConversion(Arg);
+    QualType RHSTy = RHS.get()->getType();
+    QualType EltTy = getNeonEltType(NeonTypeFlags(TV), Context);
+    if (HasConstPtr)
+      EltTy = EltTy.withConst();
+    QualType LHSTy = Context.getPointerType(EltTy);
+    AssignConvertType ConvTy;
+    ConvTy = CheckSingleAssignmentConstraints(LHSTy, RHS);
+    if (RHS.isInvalid())
+      return true;
+    if (DiagnoseAssignmentResult(ConvTy, Arg->getLocStart(), LHSTy, RHSTy,
+                                 RHS.get(), AA_Assigning))
+      return true;
+  }
+  
+  // For NEON intrinsics which take an immediate value as part of the 
+  // instruction, range check them here.
+  unsigned i = 0, l = 0, u = 0;
+  switch (BuiltinID) {
+  default: return false;
+  case ARM::BI__builtin_arm_ssat: i = 1; l = 1; u = 31; break;
+  case ARM::BI__builtin_arm_usat: i = 1; u = 31; break;
+  case ARM::BI__builtin_arm_vcvtr_f:
+  case ARM::BI__builtin_arm_vcvtr_d: i = 1; u = 1; break;
+#define GET_NEON_IMMEDIATE_CHECK
+#include "clang/Basic/arm_neon.inc"
+#undef GET_NEON_IMMEDIATE_CHECK
+  };
+
+  // Check that the immediate argument is actually a constant.
+  if (SemaBuiltinConstantArg(TheCall, i, Result))
+    return true;
+
+  // Range check against the upper/lower values for this isntruction.
+  unsigned Val = Result.getZExtValue();
+  if (Val < l || Val > (u + l))
+    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
+      << l << u+l << TheCall->getArg(i)->getSourceRange();
+
+  // FIXME: VFP Intrinsics should error if VFP not present.
+  return false;
+}
+
+/// CheckFunctionCall - Check a direct function call for various correctness
+/// and safety properties not strictly enforced by the C type system.
+bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) {
+  // Get the IdentifierInfo* for the called function.
+  IdentifierInfo *FnInfo = FDecl->getIdentifier();
+
+  // None of the checks below are needed for functions that don't have
+  // simple names (e.g., C++ conversion functions).
+  if (!FnInfo)
+    return false;
+
+  // FIXME: This mechanism should be abstracted to be less fragile and
+  // more efficient. For example, just map function ids to custom
+  // handlers.
+
+  // Printf and scanf checking.
+  for (specific_attr_iterator<FormatAttr>
+         i = FDecl->specific_attr_begin<FormatAttr>(),
+         e = FDecl->specific_attr_end<FormatAttr>(); i != e ; ++i) {
+    CheckFormatArguments(*i, TheCall);
+  }
+
+  for (specific_attr_iterator<NonNullAttr>
+         i = FDecl->specific_attr_begin<NonNullAttr>(),
+         e = FDecl->specific_attr_end<NonNullAttr>(); i != e; ++i) {
+    CheckNonNullArguments(*i, TheCall->getArgs(),
+                          TheCall->getCallee()->getLocStart());
+  }
+
+  unsigned CMId = FDecl->getMemoryFunctionKind();
+  if (CMId == 0)
+    return false;
+
+  // Handle memory setting and copying functions.
+  if (CMId == Builtin::BIstrlcpy || CMId == Builtin::BIstrlcat)
+    CheckStrlcpycatArguments(TheCall, FnInfo);
+  else if (CMId == Builtin::BIstrncat)
+    CheckStrncatArguments(TheCall, FnInfo);
+  else
+    CheckMemaccessArguments(TheCall, CMId, FnInfo);
+
+  return false;
+}
+
+bool Sema::CheckObjCMethodCall(ObjCMethodDecl *Method, SourceLocation lbrac, 
+                               Expr **Args, unsigned NumArgs) {
+  for (specific_attr_iterator<FormatAttr>
+       i = Method->specific_attr_begin<FormatAttr>(),
+       e = Method->specific_attr_end<FormatAttr>(); i != e ; ++i) {
+
+    CheckFormatArguments(*i, Args, NumArgs, false, lbrac, 
+                         Method->getSourceRange());
+  }
+
+  // diagnose nonnull arguments.
+  for (specific_attr_iterator<NonNullAttr>
+       i = Method->specific_attr_begin<NonNullAttr>(),
+       e = Method->specific_attr_end<NonNullAttr>(); i != e; ++i) {
+    CheckNonNullArguments(*i, Args, lbrac);
+  }
+
+  return false;
+}
+
+bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) {
+  const VarDecl *V = dyn_cast<VarDecl>(NDecl);
+  if (!V)
+    return false;
+
+  QualType Ty = V->getType();
+  if (!Ty->isBlockPointerType())
+    return false;
+
+  // format string checking.
+  for (specific_attr_iterator<FormatAttr>
+       i = NDecl->specific_attr_begin<FormatAttr>(),
+       e = NDecl->specific_attr_end<FormatAttr>(); i != e ; ++i) {
+    CheckFormatArguments(*i, TheCall);
+  }
+
+  return false;
+}
+
+ExprResult Sema::SemaAtomicOpsOverloaded(ExprResult TheCallResult,
+                                         AtomicExpr::AtomicOp Op) {
+  CallExpr *TheCall = cast<CallExpr>(TheCallResult.get());
+  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
+
+  // All these operations take one of the following forms:
+  enum {
+    // C    __c11_atomic_init(A *, C)
+    Init,
+    // C    __c11_atomic_load(A *, int)
+    Load,
+    // void __atomic_load(A *, CP, int)
+    Copy,
+    // C    __c11_atomic_add(A *, M, int)
+    Arithmetic,
+    // C    __atomic_exchange_n(A *, CP, int)
+    Xchg,
+    // void __atomic_exchange(A *, C *, CP, int)
+    GNUXchg,
+    // bool __c11_atomic_compare_exchange_strong(A *, C *, CP, int, int)
+    C11CmpXchg,
+    // bool __atomic_compare_exchange(A *, C *, CP, bool, int, int)
+    GNUCmpXchg
+  } Form = Init;
+  const unsigned NumArgs[] = { 2, 2, 3, 3, 3, 4, 5, 6 };
+  const unsigned NumVals[] = { 1, 0, 1, 1, 1, 2, 2, 3 };
+  // where:
+  //   C is an appropriate type,
+  //   A is volatile _Atomic(C) for __c11 builtins and is C for GNU builtins,
+  //   CP is C for __c11 builtins and GNU _n builtins and is C * otherwise,
+  //   M is C if C is an integer, and ptrdiff_t if C is a pointer, and
+  //   the int parameters are for orderings.
+
+  assert(AtomicExpr::AO__c11_atomic_init == 0 &&
+         AtomicExpr::AO__c11_atomic_fetch_xor + 1 == AtomicExpr::AO__atomic_load
+         && "need to update code for modified C11 atomics");
+  bool IsC11 = Op >= AtomicExpr::AO__c11_atomic_init &&
+               Op <= AtomicExpr::AO__c11_atomic_fetch_xor;
+  bool IsN = Op == AtomicExpr::AO__atomic_load_n ||
+             Op == AtomicExpr::AO__atomic_store_n ||
+             Op == AtomicExpr::AO__atomic_exchange_n ||
+             Op == AtomicExpr::AO__atomic_compare_exchange_n;
+  bool IsAddSub = false;
+
+  switch (Op) {
+  case AtomicExpr::AO__c11_atomic_init:
+    Form = Init;
+    break;
+
+  case AtomicExpr::AO__c11_atomic_load:
+  case AtomicExpr::AO__atomic_load_n:
+    Form = Load;
+    break;
+
+  case AtomicExpr::AO__c11_atomic_store:
+  case AtomicExpr::AO__atomic_load:
+  case AtomicExpr::AO__atomic_store:
+  case AtomicExpr::AO__atomic_store_n:
+    Form = Copy;
+    break;
+
+  case AtomicExpr::AO__c11_atomic_fetch_add:
+  case AtomicExpr::AO__c11_atomic_fetch_sub:
+  case AtomicExpr::AO__atomic_fetch_add:
+  case AtomicExpr::AO__atomic_fetch_sub:
+  case AtomicExpr::AO__atomic_add_fetch:
+  case AtomicExpr::AO__atomic_sub_fetch:
+    IsAddSub = true;
+    // Fall through.
+  case AtomicExpr::AO__c11_atomic_fetch_and:
+  case AtomicExpr::AO__c11_atomic_fetch_or:
+  case AtomicExpr::AO__c11_atomic_fetch_xor:
+  case AtomicExpr::AO__atomic_fetch_and:
+  case AtomicExpr::AO__atomic_fetch_or:
+  case AtomicExpr::AO__atomic_fetch_xor:
+  case AtomicExpr::AO__atomic_fetch_nand:
+  case AtomicExpr::AO__atomic_and_fetch:
+  case AtomicExpr::AO__atomic_or_fetch:
+  case AtomicExpr::AO__atomic_xor_fetch:
+  case AtomicExpr::AO__atomic_nand_fetch:
+    Form = Arithmetic;
+    break;
+
+  case AtomicExpr::AO__c11_atomic_exchange:
+  case AtomicExpr::AO__atomic_exchange_n:
+    Form = Xchg;
+    break;
+
+  case AtomicExpr::AO__atomic_exchange:
+    Form = GNUXchg;
+    break;
+
+  case AtomicExpr::AO__c11_atomic_compare_exchange_strong:
+  case AtomicExpr::AO__c11_atomic_compare_exchange_weak:
+    Form = C11CmpXchg;
+    break;
+
+  case AtomicExpr::AO__atomic_compare_exchange:
+  case AtomicExpr::AO__atomic_compare_exchange_n:
+    Form = GNUCmpXchg;
+    break;
+  }
+
+  // Check we have the right number of arguments.
+  if (TheCall->getNumArgs() < NumArgs[Form]) {
+    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
+      << 0 << NumArgs[Form] << TheCall->getNumArgs()
+      << TheCall->getCallee()->getSourceRange();
+    return ExprError();
+  } else if (TheCall->getNumArgs() > NumArgs[Form]) {
+    Diag(TheCall->getArg(NumArgs[Form])->getLocStart(),
+         diag::err_typecheck_call_too_many_args)
+      << 0 << NumArgs[Form] << TheCall->getNumArgs()
+      << TheCall->getCallee()->getSourceRange();
+    return ExprError();
+  }
+
+  // Inspect the first argument of the atomic operation.
+  Expr *Ptr = TheCall->getArg(0);
+  Ptr = DefaultFunctionArrayLvalueConversion(Ptr).get();
+  const PointerType *pointerType = Ptr->getType()->getAs<PointerType>();
+  if (!pointerType) {
+    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
+      << Ptr->getType() << Ptr->getSourceRange();
+    return ExprError();
+  }
+
+  // For a __c11 builtin, this should be a pointer to an _Atomic type.
+  QualType AtomTy = pointerType->getPointeeType(); // 'A'
+  QualType ValType = AtomTy; // 'C'
+  if (IsC11) {
+    if (!AtomTy->isAtomicType()) {
+      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic)
+        << Ptr->getType() << Ptr->getSourceRange();
+      return ExprError();
+    }
+    ValType = AtomTy->getAs<AtomicType>()->getValueType();
+  }
+
+  // For an arithmetic operation, the implied arithmetic must be well-formed.
+  if (Form == Arithmetic) {
+    // gcc does not enforce these rules for GNU atomics, but we do so for sanity.
+    if (IsAddSub && !ValType->isIntegerType() && !ValType->isPointerType()) {
+      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
+        << IsC11 << Ptr->getType() << Ptr->getSourceRange();
+      return ExprError();
+    }
+    if (!IsAddSub && !ValType->isIntegerType()) {
+      Diag(DRE->getLocStart(), diag::err_atomic_op_bitwise_needs_atomic_int)
+        << IsC11 << Ptr->getType() << Ptr->getSourceRange();
+      return ExprError();
+    }
+  } else if (IsN && !ValType->isIntegerType() && !ValType->isPointerType()) {
+    // For __atomic_*_n operations, the value type must be a scalar integral or
+    // pointer type which is 1, 2, 4, 8 or 16 bytes in length.
+    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
+      << IsC11 << Ptr->getType() << Ptr->getSourceRange();
+    return ExprError();
+  }
+
+  if (!IsC11 && !AtomTy.isTriviallyCopyableType(Context)) {
+    // For GNU atomics, require a trivially-copyable type. This is not part of
+    // the GNU atomics specification, but we enforce it for sanity.
+    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_trivial_copy)
+      << Ptr->getType() << Ptr->getSourceRange();
+    return ExprError();
+  }
+
+  // FIXME: For any builtin other than a load, the ValType must not be
+  // const-qualified.
+
+  switch (ValType.getObjCLifetime()) {
+  case Qualifiers::OCL_None:
+  case Qualifiers::OCL_ExplicitNone:
+    // okay
+    break;
+
+  case Qualifiers::OCL_Weak:
+  case Qualifiers::OCL_Strong:
+  case Qualifiers::OCL_Autoreleasing:
+    // FIXME: Can this happen? By this point, ValType should be known
+    // to be trivially copyable.
+    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
+      << ValType << Ptr->getSourceRange();
+    return ExprError();
+  }
+
+  QualType ResultType = ValType;
+  if (Form == Copy || Form == GNUXchg || Form == Init)
+    ResultType = Context.VoidTy;
+  else if (Form == C11CmpXchg || Form == GNUCmpXchg)
+    ResultType = Context.BoolTy;
+
+  // The type of a parameter passed 'by value'. In the GNU atomics, such
+  // arguments are actually passed as pointers.
+  QualType ByValType = ValType; // 'CP'
+  if (!IsC11 && !IsN)
+    ByValType = Ptr->getType();
+
+  // The first argument --- the pointer --- has a fixed type; we
+  // deduce the types of the rest of the arguments accordingly.  Walk
+  // the remaining arguments, converting them to the deduced value type.
+  for (unsigned i = 1; i != NumArgs[Form]; ++i) {
+    QualType Ty;
+    if (i < NumVals[Form] + 1) {
+      switch (i) {
+      case 1:
+        // The second argument is the non-atomic operand. For arithmetic, this
+        // is always passed by value, and for a compare_exchange it is always
+        // passed by address. For the rest, GNU uses by-address and C11 uses
+        // by-value.
+        assert(Form != Load);
+        if (Form == Init || (Form == Arithmetic && ValType->isIntegerType()))
+          Ty = ValType;
+        else if (Form == Copy || Form == Xchg)
+          Ty = ByValType;
+        else if (Form == Arithmetic)
+          Ty = Context.getPointerDiffType();
+        else
+          Ty = Context.getPointerType(ValType.getUnqualifiedType());
+        break;
+      case 2:
+        // The third argument to compare_exchange / GNU exchange is a
+        // (pointer to a) desired value.
+        Ty = ByValType;
+        break;
+      case 3:
+        // The fourth argument to GNU compare_exchange is a 'weak' flag.
+        Ty = Context.BoolTy;
+        break;
+      }
+    } else {
+      // The order(s) are always converted to int.
+      Ty = Context.IntTy;
+    }
+
+    InitializedEntity Entity =
+        InitializedEntity::InitializeParameter(Context, Ty, false);
+    ExprResult Arg = TheCall->getArg(i);
+    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
+    if (Arg.isInvalid())
+      return true;
+    TheCall->setArg(i, Arg.get());
+  }
+
+  // Permute the arguments into a 'consistent' order.
+  SmallVector<Expr*, 5> SubExprs;
+  SubExprs.push_back(Ptr);
+  switch (Form) {
+  case Init:
+    // Note, AtomicExpr::getVal1() has a special case for this atomic.
+    SubExprs.push_back(TheCall->getArg(1)); // Val1
+    break;
+  case Load:
+    SubExprs.push_back(TheCall->getArg(1)); // Order
+    break;
+  case Copy:
+  case Arithmetic:
+  case Xchg:
+    SubExprs.push_back(TheCall->getArg(2)); // Order
+    SubExprs.push_back(TheCall->getArg(1)); // Val1
+    break;
+  case GNUXchg:
+    // Note, AtomicExpr::getVal2() has a special case for this atomic.
+    SubExprs.push_back(TheCall->getArg(3)); // Order
+    SubExprs.push_back(TheCall->getArg(1)); // Val1
+    SubExprs.push_back(TheCall->getArg(2)); // Val2
+    break;
+  case C11CmpXchg:
+    SubExprs.push_back(TheCall->getArg(3)); // Order
+    SubExprs.push_back(TheCall->getArg(1)); // Val1
+    SubExprs.push_back(TheCall->getArg(4)); // OrderFail
+    SubExprs.push_back(TheCall->getArg(2)); // Val2
+    break;
+  case GNUCmpXchg:
+    SubExprs.push_back(TheCall->getArg(4)); // Order
+    SubExprs.push_back(TheCall->getArg(1)); // Val1
+    SubExprs.push_back(TheCall->getArg(5)); // OrderFail
+    SubExprs.push_back(TheCall->getArg(2)); // Val2
+    SubExprs.push_back(TheCall->getArg(3)); // Weak
+    break;
+  }
+
+  return Owned(new (Context) AtomicExpr(TheCall->getCallee()->getLocStart(),
+                                        SubExprs.data(), SubExprs.size(),
+                                        ResultType, Op,
+                                        TheCall->getRParenLoc()));
+}
+
+
+/// checkBuiltinArgument - Given a call to a builtin function, perform
+/// normal type-checking on the given argument, updating the call in
+/// place.  This is useful when a builtin function requires custom
+/// type-checking for some of its arguments but not necessarily all of
+/// them.
+///
+/// Returns true on error.
+static bool checkBuiltinArgument(Sema &S, CallExpr *E, unsigned ArgIndex) {
+  FunctionDecl *Fn = E->getDirectCallee();
+  assert(Fn && "builtin call without direct callee!");
+
+  ParmVarDecl *Param = Fn->getParamDecl(ArgIndex);
+  InitializedEntity Entity =
+    InitializedEntity::InitializeParameter(S.Context, Param);
+
+  ExprResult Arg = E->getArg(0);
+  Arg = S.PerformCopyInitialization(Entity, SourceLocation(), Arg);
+  if (Arg.isInvalid())
+    return true;
+
+  E->setArg(ArgIndex, Arg.take());
+  return false;
+}
+
+/// SemaBuiltinAtomicOverloaded - We have a call to a function like
+/// __sync_fetch_and_add, which is an overloaded function based on the pointer
+/// type of its first argument.  The main ActOnCallExpr routines have already
+/// promoted the types of arguments because all of these calls are prototyped as
+/// void(...).
+///
+/// This function goes through and does final semantic checking for these
+/// builtins,
+ExprResult
+Sema::SemaBuiltinAtomicOverloaded(ExprResult TheCallResult) {
+  CallExpr *TheCall = (CallExpr *)TheCallResult.get();
+  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
+  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
+
+  // Ensure that we have at least one argument to do type inference from.
+  if (TheCall->getNumArgs() < 1) {
+    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
+      << 0 << 1 << TheCall->getNumArgs()
+      << TheCall->getCallee()->getSourceRange();
+    return ExprError();
+  }
+
+  // Inspect the first argument of the atomic builtin.  This should always be
+  // a pointer type, whose element is an integral scalar or pointer type.
+  // Because it is a pointer type, we don't have to worry about any implicit
+  // casts here.
+  // FIXME: We don't allow floating point scalars as input.
+  Expr *FirstArg = TheCall->getArg(0);
+  ExprResult FirstArgResult = DefaultFunctionArrayLvalueConversion(FirstArg);
+  if (FirstArgResult.isInvalid())
+    return ExprError();
+  FirstArg = FirstArgResult.take();
+  TheCall->setArg(0, FirstArg);
+
+  const PointerType *pointerType = FirstArg->getType()->getAs<PointerType>();
+  if (!pointerType) {
+    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
+      << FirstArg->getType() << FirstArg->getSourceRange();
+    return ExprError();
+  }
+
+  QualType ValType = pointerType->getPointeeType();
+  if (!ValType->isIntegerType() && !ValType->isAnyPointerType() &&
+      !ValType->isBlockPointerType()) {
+    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr)
+      << FirstArg->getType() << FirstArg->getSourceRange();
+    return ExprError();
+  }
+
+  switch (ValType.getObjCLifetime()) {
+  case Qualifiers::OCL_None:
+  case Qualifiers::OCL_ExplicitNone:
+    // okay
+    break;
+
+  case Qualifiers::OCL_Weak:
+  case Qualifiers::OCL_Strong:
+  case Qualifiers::OCL_Autoreleasing:
+    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
+      << ValType << FirstArg->getSourceRange();
+    return ExprError();
+  }
+
+  // Strip any qualifiers off ValType.
+  ValType = ValType.getUnqualifiedType();
+
+  // The majority of builtins return a value, but a few have special return
+  // types, so allow them to override appropriately below.
+  QualType ResultType = ValType;
+
+  // We need to figure out which concrete builtin this maps onto.  For example,
+  // __sync_fetch_and_add with a 2 byte object turns into
+  // __sync_fetch_and_add_2.
+#define BUILTIN_ROW(x) \
+  { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \
+    Builtin::BI##x##_8, Builtin::BI##x##_16 }
+
+  static const unsigned BuiltinIndices[][5] = {
+    BUILTIN_ROW(__sync_fetch_and_add),
+    BUILTIN_ROW(__sync_fetch_and_sub),
+    BUILTIN_ROW(__sync_fetch_and_or),
+    BUILTIN_ROW(__sync_fetch_and_and),
+    BUILTIN_ROW(__sync_fetch_and_xor),
+
+    BUILTIN_ROW(__sync_add_and_fetch),
+    BUILTIN_ROW(__sync_sub_and_fetch),
+    BUILTIN_ROW(__sync_and_and_fetch),
+    BUILTIN_ROW(__sync_or_and_fetch),
+    BUILTIN_ROW(__sync_xor_and_fetch),
+
+    BUILTIN_ROW(__sync_val_compare_and_swap),
+    BUILTIN_ROW(__sync_bool_compare_and_swap),
+    BUILTIN_ROW(__sync_lock_test_and_set),
+    BUILTIN_ROW(__sync_lock_release),
+    BUILTIN_ROW(__sync_swap)
+  };
+#undef BUILTIN_ROW
+
+  // Determine the index of the size.
+  unsigned SizeIndex;
+  switch (Context.getTypeSizeInChars(ValType).getQuantity()) {
+  case 1: SizeIndex = 0; break;
+  case 2: SizeIndex = 1; break;
+  case 4: SizeIndex = 2; break;
+  case 8: SizeIndex = 3; break;
+  case 16: SizeIndex = 4; break;
+  default:
+    Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size)
+      << FirstArg->getType() << FirstArg->getSourceRange();
+    return ExprError();
+  }
+
+  // Each of these builtins has one pointer argument, followed by some number of
+  // values (0, 1 or 2) followed by a potentially empty varags list of stuff
+  // that we ignore.  Find out which row of BuiltinIndices to read from as well
+  // as the number of fixed args.
+  unsigned BuiltinID = FDecl->getBuiltinID();
+  unsigned BuiltinIndex, NumFixed = 1;
+  switch (BuiltinID) {
+  default: llvm_unreachable("Unknown overloaded atomic builtin!");
+  case Builtin::BI__sync_fetch_and_add: 
+  case Builtin::BI__sync_fetch_and_add_1:
+  case Builtin::BI__sync_fetch_and_add_2:
+  case Builtin::BI__sync_fetch_and_add_4:
+  case Builtin::BI__sync_fetch_and_add_8:
+  case Builtin::BI__sync_fetch_and_add_16:
+    BuiltinIndex = 0; 
+    break;
+      
+  case Builtin::BI__sync_fetch_and_sub: 
+  case Builtin::BI__sync_fetch_and_sub_1:
+  case Builtin::BI__sync_fetch_and_sub_2:
+  case Builtin::BI__sync_fetch_and_sub_4:
+  case Builtin::BI__sync_fetch_and_sub_8:
+  case Builtin::BI__sync_fetch_and_sub_16:
+    BuiltinIndex = 1; 
+    break;
+      
+  case Builtin::BI__sync_fetch_and_or:  
+  case Builtin::BI__sync_fetch_and_or_1:
+  case Builtin::BI__sync_fetch_and_or_2:
+  case Builtin::BI__sync_fetch_and_or_4:
+  case Builtin::BI__sync_fetch_and_or_8:
+  case Builtin::BI__sync_fetch_and_or_16:
+    BuiltinIndex = 2; 
+    break;
+      
+  case Builtin::BI__sync_fetch_and_and: 
+  case Builtin::BI__sync_fetch_and_and_1:
+  case Builtin::BI__sync_fetch_and_and_2:
+  case Builtin::BI__sync_fetch_and_and_4:
+  case Builtin::BI__sync_fetch_and_and_8:
+  case Builtin::BI__sync_fetch_and_and_16:
+    BuiltinIndex = 3; 
+    break;
+
+  case Builtin::BI__sync_fetch_and_xor: 
+  case Builtin::BI__sync_fetch_and_xor_1:
+  case Builtin::BI__sync_fetch_and_xor_2:
+  case Builtin::BI__sync_fetch_and_xor_4:
+  case Builtin::BI__sync_fetch_and_xor_8:
+  case Builtin::BI__sync_fetch_and_xor_16:
+    BuiltinIndex = 4; 
+    break;
+
+  case Builtin::BI__sync_add_and_fetch: 
+  case Builtin::BI__sync_add_and_fetch_1:
+  case Builtin::BI__sync_add_and_fetch_2:
+  case Builtin::BI__sync_add_and_fetch_4:
+  case Builtin::BI__sync_add_and_fetch_8:
+  case Builtin::BI__sync_add_and_fetch_16:
+    BuiltinIndex = 5; 
+    break;
+      
+  case Builtin::BI__sync_sub_and_fetch: 
+  case Builtin::BI__sync_sub_and_fetch_1:
+  case Builtin::BI__sync_sub_and_fetch_2:
+  case Builtin::BI__sync_sub_and_fetch_4:
+  case Builtin::BI__sync_sub_and_fetch_8:
+  case Builtin::BI__sync_sub_and_fetch_16:
+    BuiltinIndex = 6; 
+    break;
+      
+  case Builtin::BI__sync_and_and_fetch: 
+  case Builtin::BI__sync_and_and_fetch_1:
+  case Builtin::BI__sync_and_and_fetch_2:
+  case Builtin::BI__sync_and_and_fetch_4:
+  case Builtin::BI__sync_and_and_fetch_8:
+  case Builtin::BI__sync_and_and_fetch_16:
+    BuiltinIndex = 7; 
+    break;
+      
+  case Builtin::BI__sync_or_and_fetch:  
+  case Builtin::BI__sync_or_and_fetch_1:
+  case Builtin::BI__sync_or_and_fetch_2:
+  case Builtin::BI__sync_or_and_fetch_4:
+  case Builtin::BI__sync_or_and_fetch_8:
+  case Builtin::BI__sync_or_and_fetch_16:
+    BuiltinIndex = 8; 
+    break;
+      
+  case Builtin::BI__sync_xor_and_fetch: 
+  case Builtin::BI__sync_xor_and_fetch_1:
+  case Builtin::BI__sync_xor_and_fetch_2:
+  case Builtin::BI__sync_xor_and_fetch_4:
+  case Builtin::BI__sync_xor_and_fetch_8:
+  case Builtin::BI__sync_xor_and_fetch_16:
+    BuiltinIndex = 9; 
+    break;
+
+  case Builtin::BI__sync_val_compare_and_swap:
+  case Builtin::BI__sync_val_compare_and_swap_1:
+  case Builtin::BI__sync_val_compare_and_swap_2:
+  case Builtin::BI__sync_val_compare_and_swap_4:
+  case Builtin::BI__sync_val_compare_and_swap_8:
+  case Builtin::BI__sync_val_compare_and_swap_16:
+    BuiltinIndex = 10;
+    NumFixed = 2;
+    break;
+      
+  case Builtin::BI__sync_bool_compare_and_swap:
+  case Builtin::BI__sync_bool_compare_and_swap_1:
+  case Builtin::BI__sync_bool_compare_and_swap_2:
+  case Builtin::BI__sync_bool_compare_and_swap_4:
+  case Builtin::BI__sync_bool_compare_and_swap_8:
+  case Builtin::BI__sync_bool_compare_and_swap_16:
+    BuiltinIndex = 11;
+    NumFixed = 2;
+    ResultType = Context.BoolTy;
+    break;
+      
+  case Builtin::BI__sync_lock_test_and_set: 
+  case Builtin::BI__sync_lock_test_and_set_1:
+  case Builtin::BI__sync_lock_test_and_set_2:
+  case Builtin::BI__sync_lock_test_and_set_4:
+  case Builtin::BI__sync_lock_test_and_set_8:
+  case Builtin::BI__sync_lock_test_and_set_16:
+    BuiltinIndex = 12; 
+    break;
+      
+  case Builtin::BI__sync_lock_release:
+  case Builtin::BI__sync_lock_release_1:
+  case Builtin::BI__sync_lock_release_2:
+  case Builtin::BI__sync_lock_release_4:
+  case Builtin::BI__sync_lock_release_8:
+  case Builtin::BI__sync_lock_release_16:
+    BuiltinIndex = 13;
+    NumFixed = 0;
+    ResultType = Context.VoidTy;
+    break;
+      
+  case Builtin::BI__sync_swap: 
+  case Builtin::BI__sync_swap_1:
+  case Builtin::BI__sync_swap_2:
+  case Builtin::BI__sync_swap_4:
+  case Builtin::BI__sync_swap_8:
+  case Builtin::BI__sync_swap_16:
+    BuiltinIndex = 14; 
+    break;
+  }
+
+  // Now that we know how many fixed arguments we expect, first check that we
+  // have at least that many.
+  if (TheCall->getNumArgs() < 1+NumFixed) {
+    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
+      << 0 << 1+NumFixed << TheCall->getNumArgs()
+      << TheCall->getCallee()->getSourceRange();
+    return ExprError();
+  }
+
+  // Get the decl for the concrete builtin from this, we can tell what the
+  // concrete integer type we should convert to is.
+  unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex];
+  const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID);
+  IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName);
+  FunctionDecl *NewBuiltinDecl =
+    cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID,
+                                           TUScope, false, DRE->getLocStart()));
+
+  // The first argument --- the pointer --- has a fixed type; we
+  // deduce the types of the rest of the arguments accordingly.  Walk
+  // the remaining arguments, converting them to the deduced value type.
+  for (unsigned i = 0; i != NumFixed; ++i) {
+    ExprResult Arg = TheCall->getArg(i+1);
+
+    // GCC does an implicit conversion to the pointer or integer ValType.  This
+    // can fail in some cases (1i -> int**), check for this error case now.
+    // Initialize the argument.
+    InitializedEntity Entity = InitializedEntity::InitializeParameter(Context,
+                                                   ValType, /*consume*/ false);
+    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
+    if (Arg.isInvalid())
+      return ExprError();
+
+    // Okay, we have something that *can* be converted to the right type.  Check
+    // to see if there is a potentially weird extension going on here.  This can
+    // happen when you do an atomic operation on something like an char* and
+    // pass in 42.  The 42 gets converted to char.  This is even more strange
+    // for things like 45.123 -> char, etc.
+    // FIXME: Do this check.
+    TheCall->setArg(i+1, Arg.take());
+  }
+
+  ASTContext& Context = this->getASTContext();
+
+  // Create a new DeclRefExpr to refer to the new decl.
+  DeclRefExpr* NewDRE = DeclRefExpr::Create(
+      Context,
+      DRE->getQualifierLoc(),
+      SourceLocation(),
+      NewBuiltinDecl,
+      /*enclosing*/ false,
+      DRE->getLocation(),
+      NewBuiltinDecl->getType(),
+      DRE->getValueKind());
+
+  // Set the callee in the CallExpr.
+  // FIXME: This leaks the original parens and implicit casts.
+  ExprResult PromotedCall = UsualUnaryConversions(NewDRE);
+  if (PromotedCall.isInvalid())
+    return ExprError();
+  TheCall->setCallee(PromotedCall.take());
+
+  // Change the result type of the call to match the original value type. This
+  // is arbitrary, but the codegen for these builtins ins design to handle it
+  // gracefully.
+  TheCall->setType(ResultType);
+
+  return move(TheCallResult);
+}
+
+/// CheckObjCString - Checks that the argument to the builtin
+/// CFString constructor is correct
+/// Note: It might also make sense to do the UTF-16 conversion here (would
+/// simplify the backend).
+bool Sema::CheckObjCString(Expr *Arg) {
+  Arg = Arg->IgnoreParenCasts();
+  StringLiteral *Literal = dyn_cast<StringLiteral>(Arg);
+
+  if (!Literal || !Literal->isAscii()) {
+    Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant)
+      << Arg->getSourceRange();
+    return true;
+  }
+
+  if (Literal->containsNonAsciiOrNull()) {
+    StringRef String = Literal->getString();
+    unsigned NumBytes = String.size();
+    SmallVector<UTF16, 128> ToBuf(NumBytes);
+    const UTF8 *FromPtr = (UTF8 *)String.data();
+    UTF16 *ToPtr = &ToBuf[0];
+    
+    ConversionResult Result = ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes,
+                                                 &ToPtr, ToPtr + NumBytes,
+                                                 strictConversion);
+    // Check for conversion failure.
+    if (Result != conversionOK)
+      Diag(Arg->getLocStart(),
+           diag::warn_cfstring_truncated) << Arg->getSourceRange();
+  }
+  return false;
+}
+
+/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity.
+/// Emit an error and return true on failure, return false on success.
+bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) {
+  Expr *Fn = TheCall->getCallee();
+  if (TheCall->getNumArgs() > 2) {
+    Diag(TheCall->getArg(2)->getLocStart(),
+         diag::err_typecheck_call_too_many_args)
+      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
+      << Fn->getSourceRange()
+      << SourceRange(TheCall->getArg(2)->getLocStart(),
+                     (*(TheCall->arg_end()-1))->getLocEnd());
+    return true;
+  }
+
+  if (TheCall->getNumArgs() < 2) {
+    return Diag(TheCall->getLocEnd(),
+      diag::err_typecheck_call_too_few_args_at_least)
+      << 0 /*function call*/ << 2 << TheCall->getNumArgs();
+  }
+
+  // Type-check the first argument normally.
+  if (checkBuiltinArgument(*this, TheCall, 0))
+    return true;
+
+  // Determine whether the current function is variadic or not.
+  BlockScopeInfo *CurBlock = getCurBlock();
+  bool isVariadic;
+  if (CurBlock)
+    isVariadic = CurBlock->TheDecl->isVariadic();
+  else if (FunctionDecl *FD = getCurFunctionDecl())
+    isVariadic = FD->isVariadic();
+  else
+    isVariadic = getCurMethodDecl()->isVariadic();
+
+  if (!isVariadic) {
+    Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function);
+    return true;
+  }
+
+  // Verify that the second argument to the builtin is the last argument of the
+  // current function or method.
+  bool SecondArgIsLastNamedArgument = false;
+  const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts();
+
+  if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) {
+    if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) {
+      // FIXME: This isn't correct for methods (results in bogus warning).
+      // Get the last formal in the current function.
+      const ParmVarDecl *LastArg;
+      if (CurBlock)
+        LastArg = *(CurBlock->TheDecl->param_end()-1);
+      else if (FunctionDecl *FD = getCurFunctionDecl())
+        LastArg = *(FD->param_end()-1);
+      else
+        LastArg = *(getCurMethodDecl()->param_end()-1);
+      SecondArgIsLastNamedArgument = PV == LastArg;
+    }
+  }
+
+  if (!SecondArgIsLastNamedArgument)
+    Diag(TheCall->getArg(1)->getLocStart(),
+         diag::warn_second_parameter_of_va_start_not_last_named_argument);
+  return false;
+}
+
+/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and
+/// friends.  This is declared to take (...), so we have to check everything.
+bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) {
+  if (TheCall->getNumArgs() < 2)
+    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
+      << 0 << 2 << TheCall->getNumArgs()/*function call*/;
+  if (TheCall->getNumArgs() > 2)
+    return Diag(TheCall->getArg(2)->getLocStart(),
+                diag::err_typecheck_call_too_many_args)
+      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
+      << SourceRange(TheCall->getArg(2)->getLocStart(),
+                     (*(TheCall->arg_end()-1))->getLocEnd());
+
+  ExprResult OrigArg0 = TheCall->getArg(0);
+  ExprResult OrigArg1 = TheCall->getArg(1);
+
+  // Do standard promotions between the two arguments, returning their common
+  // type.
+  QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false);
+  if (OrigArg0.isInvalid() || OrigArg1.isInvalid())
+    return true;
+
+  // Make sure any conversions are pushed back into the call; this is
+  // type safe since unordered compare builtins are declared as "_Bool
+  // foo(...)".
+  TheCall->setArg(0, OrigArg0.get());
+  TheCall->setArg(1, OrigArg1.get());
+
+  if (OrigArg0.get()->isTypeDependent() || OrigArg1.get()->isTypeDependent())
+    return false;
+
+  // If the common type isn't a real floating type, then the arguments were
+  // invalid for this operation.
+  if (!Res->isRealFloatingType())
+    return Diag(OrigArg0.get()->getLocStart(),
+                diag::err_typecheck_call_invalid_ordered_compare)
+      << OrigArg0.get()->getType() << OrigArg1.get()->getType()
+      << SourceRange(OrigArg0.get()->getLocStart(), OrigArg1.get()->getLocEnd());
+
+  return false;
+}
+
+/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like
+/// __builtin_isnan and friends.  This is declared to take (...), so we have
+/// to check everything. We expect the last argument to be a floating point
+/// value.
+bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) {
+  if (TheCall->getNumArgs() < NumArgs)
+    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
+      << 0 << NumArgs << TheCall->getNumArgs()/*function call*/;
+  if (TheCall->getNumArgs() > NumArgs)
+    return Diag(TheCall->getArg(NumArgs)->getLocStart(),
+                diag::err_typecheck_call_too_many_args)
+      << 0 /*function call*/ << NumArgs << TheCall->getNumArgs()
+      << SourceRange(TheCall->getArg(NumArgs)->getLocStart(),
+                     (*(TheCall->arg_end()-1))->getLocEnd());
+
+  Expr *OrigArg = TheCall->getArg(NumArgs-1);
+
+  if (OrigArg->isTypeDependent())
+    return false;
+
+  // This operation requires a non-_Complex floating-point number.
+  if (!OrigArg->getType()->isRealFloatingType())
+    return Diag(OrigArg->getLocStart(),
+                diag::err_typecheck_call_invalid_unary_fp)
+      << OrigArg->getType() << OrigArg->getSourceRange();
+
+  // If this is an implicit conversion from float -> double, remove it.
+  if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) {
+    Expr *CastArg = Cast->getSubExpr();
+    if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) {
+      assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) &&
+             "promotion from float to double is the only expected cast here");
+      Cast->setSubExpr(0);
+      TheCall->setArg(NumArgs-1, CastArg);
+    }
+  }
+  
+  return false;
+}
+
+/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector.
+// This is declared to take (...), so we have to check everything.
+ExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) {
+  if (TheCall->getNumArgs() < 2)
+    return ExprError(Diag(TheCall->getLocEnd(),
+                          diag::err_typecheck_call_too_few_args_at_least)
+      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
+      << TheCall->getSourceRange());
+
+  // Determine which of the following types of shufflevector we're checking:
+  // 1) unary, vector mask: (lhs, mask)
+  // 2) binary, vector mask: (lhs, rhs, mask)
+  // 3) binary, scalar mask: (lhs, rhs, index, ..., index)
+  QualType resType = TheCall->getArg(0)->getType();
+  unsigned numElements = 0;
+  
+  if (!TheCall->getArg(0)->isTypeDependent() &&
+      !TheCall->getArg(1)->isTypeDependent()) {
+    QualType LHSType = TheCall->getArg(0)->getType();
+    QualType RHSType = TheCall->getArg(1)->getType();
+    
+    if (!LHSType->isVectorType() || !RHSType->isVectorType()) {
+      Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector)
+        << SourceRange(TheCall->getArg(0)->getLocStart(),
+                       TheCall->getArg(1)->getLocEnd());
+      return ExprError();
+    }
+    
+    numElements = LHSType->getAs<VectorType>()->getNumElements();
+    unsigned numResElements = TheCall->getNumArgs() - 2;
+
+    // Check to see if we have a call with 2 vector arguments, the unary shuffle
+    // with mask.  If so, verify that RHS is an integer vector type with the
+    // same number of elts as lhs.
+    if (TheCall->getNumArgs() == 2) {
+      if (!RHSType->hasIntegerRepresentation() || 
+          RHSType->getAs<VectorType>()->getNumElements() != numElements)
+        Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
+          << SourceRange(TheCall->getArg(1)->getLocStart(),
+                         TheCall->getArg(1)->getLocEnd());
+      numResElements = numElements;
+    }
+    else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) {
+      Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
+        << SourceRange(TheCall->getArg(0)->getLocStart(),
+                       TheCall->getArg(1)->getLocEnd());
+      return ExprError();
+    } else if (numElements != numResElements) {
+      QualType eltType = LHSType->getAs<VectorType>()->getElementType();
+      resType = Context.getVectorType(eltType, numResElements,
+                                      VectorType::GenericVector);
+    }
+  }
+
+  for (unsigned i = 2; i < TheCall->getNumArgs(); i++) {
+    if (TheCall->getArg(i)->isTypeDependent() ||
+        TheCall->getArg(i)->isValueDependent())
+      continue;
+
+    llvm::APSInt Result(32);
+    if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context))
+      return ExprError(Diag(TheCall->getLocStart(),
+                  diag::err_shufflevector_nonconstant_argument)
+                << TheCall->getArg(i)->getSourceRange());
+
+    if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2)
+      return ExprError(Diag(TheCall->getLocStart(),
+                  diag::err_shufflevector_argument_too_large)
+               << TheCall->getArg(i)->getSourceRange());
+  }
+
+  SmallVector<Expr*, 32> exprs;
+
+  for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) {
+    exprs.push_back(TheCall->getArg(i));
+    TheCall->setArg(i, 0);
+  }
+
+  return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(),
+                                            exprs.size(), resType,
+                                            TheCall->getCallee()->getLocStart(),
+                                            TheCall->getRParenLoc()));
+}
+
+/// SemaBuiltinPrefetch - Handle __builtin_prefetch.
+// This is declared to take (const void*, ...) and can take two
+// optional constant int args.
+bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) {
+  unsigned NumArgs = TheCall->getNumArgs();
+
+  if (NumArgs > 3)
+    return Diag(TheCall->getLocEnd(),
+             diag::err_typecheck_call_too_many_args_at_most)
+             << 0 /*function call*/ << 3 << NumArgs
+             << TheCall->getSourceRange();
+
+  // Argument 0 is checked for us and the remaining arguments must be
+  // constant integers.
+  for (unsigned i = 1; i != NumArgs; ++i) {
+    Expr *Arg = TheCall->getArg(i);
+    
+    llvm::APSInt Result;
+    if (SemaBuiltinConstantArg(TheCall, i, Result))
+      return true;
+
+    // FIXME: gcc issues a warning and rewrites these to 0. These
+    // seems especially odd for the third argument since the default
+    // is 3.
+    if (i == 1) {
+      if (Result.getLimitedValue() > 1)
+        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
+             << "0" << "1" << Arg->getSourceRange();
+    } else {
+      if (Result.getLimitedValue() > 3)
+        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
+            << "0" << "3" << Arg->getSourceRange();
+    }
+  }
+
+  return false;
+}
+
+/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr
+/// TheCall is a constant expression.
+bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum,
+                                  llvm::APSInt &Result) {
+  Expr *Arg = TheCall->getArg(ArgNum);
+  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
+  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
+  
+  if (Arg->isTypeDependent() || Arg->isValueDependent()) return false;
+  
+  if (!Arg->isIntegerConstantExpr(Result, Context))
+    return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type)
+                << FDecl->getDeclName() <<  Arg->getSourceRange();
+  
+  return false;
+}
+
+/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr,
+/// int type). This simply type checks that type is one of the defined
+/// constants (0-3).
+// For compatibility check 0-3, llvm only handles 0 and 2.
+bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) {
+  llvm::APSInt Result;
+  
+  // Check constant-ness first.
+  if (SemaBuiltinConstantArg(TheCall, 1, Result))
+    return true;
+
+  Expr *Arg = TheCall->getArg(1);
+  if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) {
+    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
+             << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
+  }
+
+  return false;
+}
+
+/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val).
+/// This checks that val is a constant 1.
+bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) {
+  Expr *Arg = TheCall->getArg(1);
+  llvm::APSInt Result;
+
+  // TODO: This is less than ideal. Overload this to take a value.
+  if (SemaBuiltinConstantArg(TheCall, 1, Result))
+    return true;
+  
+  if (Result != 1)
+    return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val)
+             << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
+
+  return false;
+}
+
+// Handle i > 1 ? "x" : "y", recursively.
+bool Sema::SemaCheckStringLiteral(const Expr *E, Expr **Args,
+                                  unsigned NumArgs, bool HasVAListArg,
+                                  unsigned format_idx, unsigned firstDataArg,
+                                  FormatStringType Type, bool inFunctionCall) {
+ tryAgain:
+  if (E->isTypeDependent() || E->isValueDependent())
+    return false;
+
+  E = E->IgnoreParenCasts();
+
+  if (E->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNotNull))
+    // Technically -Wformat-nonliteral does not warn about this case.
+    // The behavior of printf and friends in this case is implementation
+    // dependent.  Ideally if the format string cannot be null then
+    // it should have a 'nonnull' attribute in the function prototype.
+    return true;
+
+  switch (E->getStmtClass()) {
+  case Stmt::BinaryConditionalOperatorClass:
+  case Stmt::ConditionalOperatorClass: {
+    const AbstractConditionalOperator *C = cast<AbstractConditionalOperator>(E);
+    return SemaCheckStringLiteral(C->getTrueExpr(), Args, NumArgs, HasVAListArg,
+                                  format_idx, firstDataArg, Type,
+                                  inFunctionCall)
+       && SemaCheckStringLiteral(C->getFalseExpr(), Args, NumArgs, HasVAListArg,
+                                 format_idx, firstDataArg, Type,
+                                 inFunctionCall);
+  }
+
+  case Stmt::ImplicitCastExprClass: {
+    E = cast<ImplicitCastExpr>(E)->getSubExpr();
+    goto tryAgain;
+  }
+
+  case Stmt::OpaqueValueExprClass:
+    if (const Expr *src = cast<OpaqueValueExpr>(E)->getSourceExpr()) {
+      E = src;
+      goto tryAgain;
+    }
+    return false;
+
+  case Stmt::PredefinedExprClass:
+    // While __func__, etc., are technically not string literals, they
+    // cannot contain format specifiers and thus are not a security
+    // liability.
+    return true;
+      
+  case Stmt::DeclRefExprClass: {
+    const DeclRefExpr *DR = cast<DeclRefExpr>(E);
+
+    // As an exception, do not flag errors for variables binding to
+    // const string literals.
+    if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
+      bool isConstant = false;
+      QualType T = DR->getType();
+
+      if (const ArrayType *AT = Context.getAsArrayType(T)) {
+        isConstant = AT->getElementType().isConstant(Context);
+      } else if (const PointerType *PT = T->getAs<PointerType>()) {
+        isConstant = T.isConstant(Context) &&
+                     PT->getPointeeType().isConstant(Context);
+      } else if (T->isObjCObjectPointerType()) {
+        // In ObjC, there is usually no "const ObjectPointer" type,
+        // so don't check if the pointee type is constant.
+        isConstant = T.isConstant(Context);
+      }
+
+      if (isConstant) {
+        if (const Expr *Init = VD->getAnyInitializer())
+          return SemaCheckStringLiteral(Init, Args, NumArgs,
+                                        HasVAListArg, format_idx, firstDataArg,
+                                        Type, /*inFunctionCall*/false);
+      }
+
+      // For vprintf* functions (i.e., HasVAListArg==true), we add a
+      // special check to see if the format string is a function parameter
+      // of the function calling the printf function.  If the function
+      // has an attribute indicating it is a printf-like function, then we
+      // should suppress warnings concerning non-literals being used in a call
+      // to a vprintf function.  For example:
+      //
+      // void
+      // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){
+      //      va_list ap;
+      //      va_start(ap, fmt);
+      //      vprintf(fmt, ap);  // Do NOT emit a warning about "fmt".
+      //      ...
+      //
+      if (HasVAListArg) {
+        if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(VD)) {
+          if (const NamedDecl *ND = dyn_cast<NamedDecl>(PV->getDeclContext())) {
+            int PVIndex = PV->getFunctionScopeIndex() + 1;
+            for (specific_attr_iterator<FormatAttr>
+                 i = ND->specific_attr_begin<FormatAttr>(),
+                 e = ND->specific_attr_end<FormatAttr>(); i != e ; ++i) {
+              FormatAttr *PVFormat = *i;
+              // adjust for implicit parameter
+              if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
+                if (MD->isInstance())
+                  ++PVIndex;
+              // We also check if the formats are compatible.
+              // We can't pass a 'scanf' string to a 'printf' function.
+              if (PVIndex == PVFormat->getFormatIdx() &&
+                  Type == GetFormatStringType(PVFormat))
+                return true;
+            }
+          }
+        }
+      }
+    }
+
+    return false;
+  }
+
+  case Stmt::CallExprClass:
+  case Stmt::CXXMemberCallExprClass: {
+    const CallExpr *CE = cast<CallExpr>(E);
+    if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl())) {
+      if (const FormatArgAttr *FA = ND->getAttr<FormatArgAttr>()) {
+        unsigned ArgIndex = FA->getFormatIdx();
+        if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
+          if (MD->isInstance())
+            --ArgIndex;
+        const Expr *Arg = CE->getArg(ArgIndex - 1);
+
+        return SemaCheckStringLiteral(Arg, Args, NumArgs, HasVAListArg,
+                                      format_idx, firstDataArg, Type,
+                                      inFunctionCall);
+      }
+    }
+
+    return false;
+  }
+  case Stmt::ObjCStringLiteralClass:
+  case Stmt::StringLiteralClass: {
+    const StringLiteral *StrE = NULL;
+
+    if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E))
+      StrE = ObjCFExpr->getString();
+    else
+      StrE = cast<StringLiteral>(E);
+
+    if (StrE) {
+      CheckFormatString(StrE, E, Args, NumArgs, HasVAListArg, format_idx,
+                        firstDataArg, Type, inFunctionCall);
+      return true;
+    }
+
+    return false;
+  }
+
+  default:
+    return false;
+  }
+}
+
+void
+Sema::CheckNonNullArguments(const NonNullAttr *NonNull,
+                            const Expr * const *ExprArgs,
+                            SourceLocation CallSiteLoc) {
+  for (NonNullAttr::args_iterator i = NonNull->args_begin(),
+                                  e = NonNull->args_end();
+       i != e; ++i) {
+    const Expr *ArgExpr = ExprArgs[*i];
+    if (ArgExpr->isNullPointerConstant(Context,
+                                       Expr::NPC_ValueDependentIsNotNull))
+      Diag(CallSiteLoc, diag::warn_null_arg) << ArgExpr->getSourceRange();
+  }
+}
+
+Sema::FormatStringType Sema::GetFormatStringType(const FormatAttr *Format) {
+  return llvm::StringSwitch<FormatStringType>(Format->getType())
+  .Case("scanf", FST_Scanf)
+  .Cases("printf", "printf0", FST_Printf)
+  .Cases("NSString", "CFString", FST_NSString)
+  .Case("strftime", FST_Strftime)
+  .Case("strfmon", FST_Strfmon)
+  .Cases("kprintf", "cmn_err", "vcmn_err", "zcmn_err", FST_Kprintf)
+  .Default(FST_Unknown);
+}
+
+/// CheckPrintfScanfArguments - Check calls to printf and scanf (and similar
+/// functions) for correct use of format strings.
+void Sema::CheckFormatArguments(const FormatAttr *Format, CallExpr *TheCall) {
+  bool IsCXXMember = false;
+  // The way the format attribute works in GCC, the implicit this argument
+  // of member functions is counted. However, it doesn't appear in our own
+  // lists, so decrement format_idx in that case.
+  IsCXXMember = isa<CXXMemberCallExpr>(TheCall);
+  CheckFormatArguments(Format, TheCall->getArgs(), TheCall->getNumArgs(),
+                       IsCXXMember, TheCall->getRParenLoc(), 
+                       TheCall->getCallee()->getSourceRange());
+}
+
+void Sema::CheckFormatArguments(const FormatAttr *Format, Expr **Args,
+                                unsigned NumArgs, bool IsCXXMember,
+                                SourceLocation Loc, SourceRange Range) {
+  bool HasVAListArg = Format->getFirstArg() == 0;
+  unsigned format_idx = Format->getFormatIdx() - 1;
+  unsigned firstDataArg = HasVAListArg ? 0 : Format->getFirstArg() - 1;
+  if (IsCXXMember) {
+    if (format_idx == 0)
+      return;
+    --format_idx;
+    if(firstDataArg != 0)
+      --firstDataArg;
+  }
+  CheckFormatArguments(Args, NumArgs, HasVAListArg, format_idx,
+                       firstDataArg, GetFormatStringType(Format), Loc, Range);
+}
+
+void Sema::CheckFormatArguments(Expr **Args, unsigned NumArgs,
+                                bool HasVAListArg, unsigned format_idx,
+                                unsigned firstDataArg, FormatStringType Type,
+                                SourceLocation Loc, SourceRange Range) {
+  // CHECK: printf/scanf-like function is called with no format string.
+  if (format_idx >= NumArgs) {
+    Diag(Loc, diag::warn_missing_format_string) << Range;
+    return;
+  }
+
+  const Expr *OrigFormatExpr = Args[format_idx]->IgnoreParenCasts();
+
+  // CHECK: format string is not a string literal.
+  //
+  // Dynamically generated format strings are difficult to
+  // automatically vet at compile time.  Requiring that format strings
+  // are string literals: (1) permits the checking of format strings by
+  // the compiler and thereby (2) can practically remove the source of
+  // many format string exploits.
+
+  // Format string can be either ObjC string (e.g. @"%d") or
+  // C string (e.g. "%d")
+  // ObjC string uses the same format specifiers as C string, so we can use
+  // the same format string checking logic for both ObjC and C strings.
+  if (SemaCheckStringLiteral(OrigFormatExpr, Args, NumArgs, HasVAListArg,
+                             format_idx, firstDataArg, Type))
+    return;  // Literal format string found, check done!
+
+  // Strftime is particular as it always uses a single 'time' argument,
+  // so it is safe to pass a non-literal string.
+  if (Type == FST_Strftime)
+    return;
+
+  // Do not emit diag when the string param is a macro expansion and the
+  // format is either NSString or CFString. This is a hack to prevent
+  // diag when using the NSLocalizedString and CFCopyLocalizedString macros
+  // which are usually used in place of NS and CF string literals.
+  if (Type == FST_NSString && Args[format_idx]->getLocStart().isMacroID())
+    return;
+
+  // If there are no arguments specified, warn with -Wformat-security, otherwise
+  // warn only with -Wformat-nonliteral.
+  if (NumArgs == format_idx+1)
+    Diag(Args[format_idx]->getLocStart(),
+         diag::warn_format_nonliteral_noargs)
+      << OrigFormatExpr->getSourceRange();
+  else
+    Diag(Args[format_idx]->getLocStart(),
+         diag::warn_format_nonliteral)
+           << OrigFormatExpr->getSourceRange();
+}
+
+namespace {
+class CheckFormatHandler : public analyze_format_string::FormatStringHandler {
+protected:
+  Sema &S;
+  const StringLiteral *FExpr;
+  const Expr *OrigFormatExpr;
+  const unsigned FirstDataArg;
+  const unsigned NumDataArgs;
+  const bool IsObjCLiteral;
+  const char *Beg; // Start of format string.
+  const bool HasVAListArg;
+  const Expr * const *Args;
+  const unsigned NumArgs;
+  unsigned FormatIdx;
+  llvm::BitVector CoveredArgs;
+  bool usesPositionalArgs;
+  bool atFirstArg;
+  bool inFunctionCall;
+public:
+  CheckFormatHandler(Sema &s, const StringLiteral *fexpr,
+                     const Expr *origFormatExpr, unsigned firstDataArg,
+                     unsigned numDataArgs, bool isObjCLiteral,
+                     const char *beg, bool hasVAListArg,
+                     Expr **args, unsigned numArgs,
+                     unsigned formatIdx, bool inFunctionCall)
+    : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr),
+      FirstDataArg(firstDataArg),
+      NumDataArgs(numDataArgs),
+      IsObjCLiteral(isObjCLiteral), Beg(beg),
+      HasVAListArg(hasVAListArg),
+      Args(args), NumArgs(numArgs), FormatIdx(formatIdx),
+      usesPositionalArgs(false), atFirstArg(true),
+      inFunctionCall(inFunctionCall) {
+        CoveredArgs.resize(numDataArgs);
+        CoveredArgs.reset();
+      }
+
+  void DoneProcessing();
+
+  void HandleIncompleteSpecifier(const char *startSpecifier,
+                                 unsigned specifierLen);
+
+  void HandleNonStandardLengthModifier(
+      const analyze_format_string::LengthModifier &LM,
+      const char *startSpecifier, unsigned specifierLen);
+
+  void HandleNonStandardConversionSpecifier(
+      const analyze_format_string::ConversionSpecifier &CS,
+      const char *startSpecifier, unsigned specifierLen);
+
+  void HandleNonStandardConversionSpecification(
+      const analyze_format_string::LengthModifier &LM,
+      const analyze_format_string::ConversionSpecifier &CS,
+      const char *startSpecifier, unsigned specifierLen);
+
+  virtual void HandlePosition(const char *startPos, unsigned posLen);
+
+  virtual void HandleInvalidPosition(const char *startSpecifier,
+                                     unsigned specifierLen,
+                                     analyze_format_string::PositionContext p);
+
+  virtual void HandleZeroPosition(const char *startPos, unsigned posLen);
+
+  void HandleNullChar(const char *nullCharacter);
+
+  template <typename Range>
+  static void EmitFormatDiagnostic(Sema &S, bool inFunctionCall,
+                                   const Expr *ArgumentExpr,
+                                   PartialDiagnostic PDiag,
+                                   SourceLocation StringLoc,
+                                   bool IsStringLocation, Range StringRange,
+                                   FixItHint Fixit = FixItHint());
+
+protected:
+  bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc,
+                                        const char *startSpec,
+                                        unsigned specifierLen,
+                                        const char *csStart, unsigned csLen);
+
+  void HandlePositionalNonpositionalArgs(SourceLocation Loc,
+                                         const char *startSpec,
+                                         unsigned specifierLen);
+  
+  SourceRange getFormatStringRange();
+  CharSourceRange getSpecifierRange(const char *startSpecifier,
+                                    unsigned specifierLen);
+  SourceLocation getLocationOfByte(const char *x);
+
+  const Expr *getDataArg(unsigned i) const;
+  
+  bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS,
+                    const analyze_format_string::ConversionSpecifier &CS,
+                    const char *startSpecifier, unsigned specifierLen,
+                    unsigned argIndex);
+
+  template <typename Range>
+  void EmitFormatDiagnostic(PartialDiagnostic PDiag, SourceLocation StringLoc,
+                            bool IsStringLocation, Range StringRange,
+                            FixItHint Fixit = FixItHint());
+
+  void CheckPositionalAndNonpositionalArgs(
+      const analyze_format_string::FormatSpecifier *FS);
+};
+}
+
+SourceRange CheckFormatHandler::getFormatStringRange() {
+  return OrigFormatExpr->getSourceRange();
+}
+
+CharSourceRange CheckFormatHandler::
+getSpecifierRange(const char *startSpecifier, unsigned specifierLen) {
+  SourceLocation Start = getLocationOfByte(startSpecifier);
+  SourceLocation End   = getLocationOfByte(startSpecifier + specifierLen - 1);
+
+  // Advance the end SourceLocation by one due to half-open ranges.
+  End = End.getLocWithOffset(1);
+
+  return CharSourceRange::getCharRange(Start, End);
+}
+
+SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) {
+  return S.getLocationOfStringLiteralByte(FExpr, x - Beg);
+}
+
+void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier,
+                                                   unsigned specifierLen){
+  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_incomplete_specifier),
+                       getLocationOfByte(startSpecifier),
+                       /*IsStringLocation*/true,
+                       getSpecifierRange(startSpecifier, specifierLen));
+}
+
+void CheckFormatHandler::HandleNonStandardLengthModifier(
+    const analyze_format_string::LengthModifier &LM,
+    const char *startSpecifier, unsigned specifierLen) {
+  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard) << LM.toString()
+                       << 0,
+                       getLocationOfByte(LM.getStart()),
+                       /*IsStringLocation*/true,
+                       getSpecifierRange(startSpecifier, specifierLen));
+}
+
+void CheckFormatHandler::HandleNonStandardConversionSpecifier(
+    const analyze_format_string::ConversionSpecifier &CS,
+    const char *startSpecifier, unsigned specifierLen) {
+  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard) << CS.toString()
+                       << 1,
+                       getLocationOfByte(CS.getStart()),
+                       /*IsStringLocation*/true,
+                       getSpecifierRange(startSpecifier, specifierLen));
+}
+
+void CheckFormatHandler::HandleNonStandardConversionSpecification(
+    const analyze_format_string::LengthModifier &LM,
+    const analyze_format_string::ConversionSpecifier &CS,
+    const char *startSpecifier, unsigned specifierLen) {
+  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard_conversion_spec)
+                       << LM.toString() << CS.toString(),
+                       getLocationOfByte(LM.getStart()),
+                       /*IsStringLocation*/true,
+                       getSpecifierRange(startSpecifier, specifierLen));
+}
+
+void CheckFormatHandler::HandlePosition(const char *startPos,
+                                        unsigned posLen) {
+  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard_positional_arg),
+                               getLocationOfByte(startPos),
+                               /*IsStringLocation*/true,
+                               getSpecifierRange(startPos, posLen));
+}
+
+void
+CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen,
+                                     analyze_format_string::PositionContext p) {
+  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_positional_specifier)
+                         << (unsigned) p,
+                       getLocationOfByte(startPos), /*IsStringLocation*/true,
+                       getSpecifierRange(startPos, posLen));
+}
+
+void CheckFormatHandler::HandleZeroPosition(const char *startPos,
+                                            unsigned posLen) {
+  EmitFormatDiagnostic(S.PDiag(diag::warn_format_zero_positional_specifier),
+                               getLocationOfByte(startPos),
+                               /*IsStringLocation*/true,
+                               getSpecifierRange(startPos, posLen));
+}
+
+void CheckFormatHandler::HandleNullChar(const char *nullCharacter) {
+  if (!IsObjCLiteral) {
+    // The presence of a null character is likely an error.
+    EmitFormatDiagnostic(
+      S.PDiag(diag::warn_printf_format_string_contains_null_char),
+      getLocationOfByte(nullCharacter), /*IsStringLocation*/true,
+      getFormatStringRange());
+  }
+}
+
+const Expr *CheckFormatHandler::getDataArg(unsigned i) const {
+  return Args[FirstDataArg + i];
+}
+
+void CheckFormatHandler::DoneProcessing() {
+    // Does the number of data arguments exceed the number of
+    // format conversions in the format string?
+  if (!HasVAListArg) {
+      // Find any arguments that weren't covered.
+    CoveredArgs.flip();
+    signed notCoveredArg = CoveredArgs.find_first();
+    if (notCoveredArg >= 0) {
+      assert((unsigned)notCoveredArg < NumDataArgs);
+      EmitFormatDiagnostic(S.PDiag(diag::warn_printf_data_arg_not_used),
+                           getDataArg((unsigned) notCoveredArg)->getLocStart(),
+                           /*IsStringLocation*/false, getFormatStringRange());
+    }
+  }
+}
+
+bool
+CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex,
+                                                     SourceLocation Loc,
+                                                     const char *startSpec,
+                                                     unsigned specifierLen,
+                                                     const char *csStart,
+                                                     unsigned csLen) {
+  
+  bool keepGoing = true;
+  if (argIndex < NumDataArgs) {
+    // Consider the argument coverered, even though the specifier doesn't
+    // make sense.
+    CoveredArgs.set(argIndex);
+  }
+  else {
+    // If argIndex exceeds the number of data arguments we
+    // don't issue a warning because that is just a cascade of warnings (and
+    // they may have intended '%%' anyway). We don't want to continue processing
+    // the format string after this point, however, as we will like just get
+    // gibberish when trying to match arguments.
+    keepGoing = false;
+  }
+  
+  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_conversion)
+                         << StringRef(csStart, csLen),
+                       Loc, /*IsStringLocation*/true,
+                       getSpecifierRange(startSpec, specifierLen));
+  
+  return keepGoing;
+}
+
+void
+CheckFormatHandler::HandlePositionalNonpositionalArgs(SourceLocation Loc,
+                                                      const char *startSpec,
+                                                      unsigned specifierLen) {
+  EmitFormatDiagnostic(
+    S.PDiag(diag::warn_format_mix_positional_nonpositional_args),
+    Loc, /*isStringLoc*/true, getSpecifierRange(startSpec, specifierLen));
+}
+
+bool
+CheckFormatHandler::CheckNumArgs(
+  const analyze_format_string::FormatSpecifier &FS,
+  const analyze_format_string::ConversionSpecifier &CS,
+  const char *startSpecifier, unsigned specifierLen, unsigned argIndex) {
+
+  if (argIndex >= NumDataArgs) {
+    PartialDiagnostic PDiag = FS.usesPositionalArg()
+      ? (S.PDiag(diag::warn_printf_positional_arg_exceeds_data_args)
+           << (argIndex+1) << NumDataArgs)
+      : S.PDiag(diag::warn_printf_insufficient_data_args);
+    EmitFormatDiagnostic(
+      PDiag, getLocationOfByte(CS.getStart()), /*IsStringLocation*/true,
+      getSpecifierRange(startSpecifier, specifierLen));
+    return false;
+  }
+  return true;
+}
+
+template<typename Range>
+void CheckFormatHandler::EmitFormatDiagnostic(PartialDiagnostic PDiag,
+                                              SourceLocation Loc,
+                                              bool IsStringLocation,
+                                              Range StringRange,
+                                              FixItHint FixIt) {
+  EmitFormatDiagnostic(S, inFunctionCall, Args[FormatIdx], PDiag,
+                       Loc, IsStringLocation, StringRange, FixIt);
+}
+
+/// \brief If the format string is not within the funcion call, emit a note
+/// so that the function call and string are in diagnostic messages.
+///
+/// \param inFunctionCall if true, the format string is within the function
+/// call and only one diagnostic message will be produced.  Otherwise, an
+/// extra note will be emitted pointing to location of the format string.
+///
+/// \param ArgumentExpr the expression that is passed as the format string
+/// argument in the function call.  Used for getting locations when two
+/// diagnostics are emitted.
+///
+/// \param PDiag the callee should already have provided any strings for the
+/// diagnostic message.  This function only adds locations and fixits
+/// to diagnostics.
+///
+/// \param Loc primary location for diagnostic.  If two diagnostics are
+/// required, one will be at Loc and a new SourceLocation will be created for
+/// the other one.
+///
+/// \param IsStringLocation if true, Loc points to the format string should be
+/// used for the note.  Otherwise, Loc points to the argument list and will
+/// be used with PDiag.
+///
+/// \param StringRange some or all of the string to highlight.  This is
+/// templated so it can accept either a CharSourceRange or a SourceRange.
+///
+/// \param Fixit optional fix it hint for the format string.
+template<typename Range>
+void CheckFormatHandler::EmitFormatDiagnostic(Sema &S, bool InFunctionCall,
+                                              const Expr *ArgumentExpr,
+                                              PartialDiagnostic PDiag,
+                                              SourceLocation Loc,
+                                              bool IsStringLocation,
+                                              Range StringRange,
+                                              FixItHint FixIt) {
+  if (InFunctionCall)
+    S.Diag(Loc, PDiag) << StringRange << FixIt;
+  else {
+    S.Diag(IsStringLocation ? ArgumentExpr->getExprLoc() : Loc, PDiag)
+      << ArgumentExpr->getSourceRange();
+    S.Diag(IsStringLocation ? Loc : StringRange.getBegin(),
+           diag::note_format_string_defined)
+      << StringRange << FixIt;
+  }
+}
+
+//===--- CHECK: Printf format string checking ------------------------------===//
+
+namespace {
+class CheckPrintfHandler : public CheckFormatHandler {
+public:
+  CheckPrintfHandler(Sema &s, const StringLiteral *fexpr,
+                     const Expr *origFormatExpr, unsigned firstDataArg,
+                     unsigned numDataArgs, bool isObjCLiteral,
+                     const char *beg, bool hasVAListArg,
+                     Expr **Args, unsigned NumArgs,
+                     unsigned formatIdx, bool inFunctionCall)
+  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
+                       numDataArgs, isObjCLiteral, beg, hasVAListArg,
+                       Args, NumArgs, formatIdx, inFunctionCall) {}
+  
+  
+  bool HandleInvalidPrintfConversionSpecifier(
+                                      const analyze_printf::PrintfSpecifier &FS,
+                                      const char *startSpecifier,
+                                      unsigned specifierLen);
+  
+  bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS,
+                             const char *startSpecifier,
+                             unsigned specifierLen);
+  
+  bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k,
+                    const char *startSpecifier, unsigned specifierLen);
+  void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS,
+                           const analyze_printf::OptionalAmount &Amt,
+                           unsigned type,
+                           const char *startSpecifier, unsigned specifierLen);
+  void HandleFlag(const analyze_printf::PrintfSpecifier &FS,
+                  const analyze_printf::OptionalFlag &flag,
+                  const char *startSpecifier, unsigned specifierLen);
+  void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS,
+                         const analyze_printf::OptionalFlag &ignoredFlag,
+                         const analyze_printf::OptionalFlag &flag,
+                         const char *startSpecifier, unsigned specifierLen);
+};  
+}
+
+bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier(
+                                      const analyze_printf::PrintfSpecifier &FS,
+                                      const char *startSpecifier,
+                                      unsigned specifierLen) {
+  const analyze_printf::PrintfConversionSpecifier &CS =
+    FS.getConversionSpecifier();
+  
+  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
+                                          getLocationOfByte(CS.getStart()),
+                                          startSpecifier, specifierLen,
+                                          CS.getStart(), CS.getLength());
+}
+
+bool CheckPrintfHandler::HandleAmount(
+                               const analyze_format_string::OptionalAmount &Amt,
+                               unsigned k, const char *startSpecifier,
+                               unsigned specifierLen) {
+
+  if (Amt.hasDataArgument()) {
+    if (!HasVAListArg) {
+      unsigned argIndex = Amt.getArgIndex();
+      if (argIndex >= NumDataArgs) {
+        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_missing_arg)
+                               << k,
+                             getLocationOfByte(Amt.getStart()),
+                             /*IsStringLocation*/true,
+                             getSpecifierRange(startSpecifier, specifierLen));
+        // Don't do any more checking.  We will just emit
+        // spurious errors.
+        return false;
+      }
+
+      // Type check the data argument.  It should be an 'int'.
+      // Although not in conformance with C99, we also allow the argument to be
+      // an 'unsigned int' as that is a reasonably safe case.  GCC also
+      // doesn't emit a warning for that case.
+      CoveredArgs.set(argIndex);
+      const Expr *Arg = getDataArg(argIndex);
+      QualType T = Arg->getType();
+
+      const analyze_printf::ArgTypeResult &ATR = Amt.getArgType(S.Context);
+      assert(ATR.isValid());
+
+      if (!ATR.matchesType(S.Context, T)) {
+        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_wrong_type)
+                               << k << ATR.getRepresentativeTypeName(S.Context)
+                               << T << Arg->getSourceRange(),
+                             getLocationOfByte(Amt.getStart()),
+                             /*IsStringLocation*/true,
+                             getSpecifierRange(startSpecifier, specifierLen));
+        // Don't do any more checking.  We will just emit
+        // spurious errors.
+        return false;
+      }
+    }
+  }
+  return true;
+}
+
+void CheckPrintfHandler::HandleInvalidAmount(
+                                      const analyze_printf::PrintfSpecifier &FS,
+                                      const analyze_printf::OptionalAmount &Amt,
+                                      unsigned type,
+                                      const char *startSpecifier,
+                                      unsigned specifierLen) {
+  const analyze_printf::PrintfConversionSpecifier &CS =
+    FS.getConversionSpecifier();
+
+  FixItHint fixit =
+    Amt.getHowSpecified() == analyze_printf::OptionalAmount::Constant
+      ? FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(),
+                                 Amt.getConstantLength()))
+      : FixItHint();
+
+  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_optional_amount)
+                         << type << CS.toString(),
+                       getLocationOfByte(Amt.getStart()),
+                       /*IsStringLocation*/true,
+                       getSpecifierRange(startSpecifier, specifierLen),
+                       fixit);
+}
+
+void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS,
+                                    const analyze_printf::OptionalFlag &flag,
+                                    const char *startSpecifier,
+                                    unsigned specifierLen) {
+  // Warn about pointless flag with a fixit removal.
+  const analyze_printf::PrintfConversionSpecifier &CS =
+    FS.getConversionSpecifier();
+  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_flag)
+                         << flag.toString() << CS.toString(),
+                       getLocationOfByte(flag.getPosition()),
+                       /*IsStringLocation*/true,
+                       getSpecifierRange(startSpecifier, specifierLen),
+                       FixItHint::CreateRemoval(
+                         getSpecifierRange(flag.getPosition(), 1)));
+}
+
+void CheckPrintfHandler::HandleIgnoredFlag(
+                                const analyze_printf::PrintfSpecifier &FS,
+                                const analyze_printf::OptionalFlag &ignoredFlag,
+                                const analyze_printf::OptionalFlag &flag,
+                                const char *startSpecifier,
+                                unsigned specifierLen) {
+  // Warn about ignored flag with a fixit removal.
+  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_ignored_flag)
+                         << ignoredFlag.toString() << flag.toString(),
+                       getLocationOfByte(ignoredFlag.getPosition()),
+                       /*IsStringLocation*/true,
+                       getSpecifierRange(startSpecifier, specifierLen),
+                       FixItHint::CreateRemoval(
+                         getSpecifierRange(ignoredFlag.getPosition(), 1)));
+}
+
+bool
+CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier
+                                            &FS,
+                                          const char *startSpecifier,
+                                          unsigned specifierLen) {
+
+  using namespace analyze_format_string;
+  using namespace analyze_printf;  
+  const PrintfConversionSpecifier &CS = FS.getConversionSpecifier();
+
+  if (FS.consumesDataArgument()) {
+    if (atFirstArg) {
+        atFirstArg = false;
+        usesPositionalArgs = FS.usesPositionalArg();
+    }
+    else if (usesPositionalArgs != FS.usesPositionalArg()) {
+      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
+                                        startSpecifier, specifierLen);
+      return false;
+    }
+  }
+
+  // First check if the field width, precision, and conversion specifier
+  // have matching data arguments.
+  if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0,
+                    startSpecifier, specifierLen)) {
+    return false;
+  }
+
+  if (!HandleAmount(FS.getPrecision(), /* precision */ 1,
+                    startSpecifier, specifierLen)) {
+    return false;
+  }
+
+  if (!CS.consumesDataArgument()) {
+    // FIXME: Technically specifying a precision or field width here
+    // makes no sense.  Worth issuing a warning at some point.
+    return true;
+  }
+
+  // Consume the argument.
+  unsigned argIndex = FS.getArgIndex();
+  if (argIndex < NumDataArgs) {
+    // The check to see if the argIndex is valid will come later.
+    // We set the bit here because we may exit early from this
+    // function if we encounter some other error.
+    CoveredArgs.set(argIndex);
+  }
+
+  // Check for using an Objective-C specific conversion specifier
+  // in a non-ObjC literal.
+  if (!IsObjCLiteral && CS.isObjCArg()) {
+    return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier,
+                                                  specifierLen);
+  }
+
+  // Check for invalid use of field width
+  if (!FS.hasValidFieldWidth()) {
+    HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0,
+        startSpecifier, specifierLen);
+  }
+
+  // Check for invalid use of precision
+  if (!FS.hasValidPrecision()) {
+    HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1,
+        startSpecifier, specifierLen);
+  }
+
+  // Check each flag does not conflict with any other component.
+  if (!FS.hasValidThousandsGroupingPrefix())
+    HandleFlag(FS, FS.hasThousandsGrouping(), startSpecifier, specifierLen);
+  if (!FS.hasValidLeadingZeros())
+    HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen);
+  if (!FS.hasValidPlusPrefix())
+    HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen);
+  if (!FS.hasValidSpacePrefix())
+    HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen);
+  if (!FS.hasValidAlternativeForm())
+    HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen);
+  if (!FS.hasValidLeftJustified())
+    HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen);
+
+  // Check that flags are not ignored by another flag
+  if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+'
+    HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(),
+        startSpecifier, specifierLen);
+  if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-'
+    HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(),
+            startSpecifier, specifierLen);
+
+  // Check the length modifier is valid with the given conversion specifier.
+  const LengthModifier &LM = FS.getLengthModifier();
+  if (!FS.hasValidLengthModifier())
+    EmitFormatDiagnostic(S.PDiag(diag::warn_format_nonsensical_length)
+                           << LM.toString() << CS.toString(),
+                         getLocationOfByte(LM.getStart()),
+                         /*IsStringLocation*/true,
+                         getSpecifierRange(startSpecifier, specifierLen),
+                         FixItHint::CreateRemoval(
+                           getSpecifierRange(LM.getStart(),
+                                             LM.getLength())));
+  if (!FS.hasStandardLengthModifier())
+    HandleNonStandardLengthModifier(LM, startSpecifier, specifierLen);
+  if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
+    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
+  if (!FS.hasStandardLengthConversionCombination())
+    HandleNonStandardConversionSpecification(LM, CS, startSpecifier,
+                                             specifierLen);
+
+  // Are we using '%n'?
+  if (CS.getKind() == ConversionSpecifier::nArg) {
+    // Issue a warning about this being a possible security issue.
+    EmitFormatDiagnostic(S.PDiag(diag::warn_printf_write_back),
+                         getLocationOfByte(CS.getStart()),
+                         /*IsStringLocation*/true,
+                         getSpecifierRange(startSpecifier, specifierLen));
+    // Continue checking the other format specifiers.
+    return true;
+  }
+
+  // The remaining checks depend on the data arguments.
+  if (HasVAListArg)
+    return true;
+
+  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
+    return false;
+
+  // Now type check the data expression that matches the
+  // format specifier.
+  const Expr *Ex = getDataArg(argIndex);
+  const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context,
+                                                           IsObjCLiteral);
+  if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) {
+    // Check if we didn't match because of an implicit cast from a 'char'
+    // or 'short' to an 'int'.  This is done because printf is a varargs
+    // function.
+    if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex))
+      if (ICE->getType() == S.Context.IntTy) {
+        // All further checking is done on the subexpression.
+        Ex = ICE->getSubExpr();
+        if (ATR.matchesType(S.Context, Ex->getType()))
+          return true;
+      }
+
+    // We may be able to offer a FixItHint if it is a supported type.
+    PrintfSpecifier fixedFS = FS;
+    bool success = fixedFS.fixType(Ex->getType(), S.getLangOpts(),
+                                   S.Context, IsObjCLiteral);
+
+    if (success) {
+      // Get the fix string from the fixed format specifier
+      SmallString<128> buf;
+      llvm::raw_svector_ostream os(buf);
+      fixedFS.toString(os);
+
+      EmitFormatDiagnostic(
+        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
+          << ATR.getRepresentativeTypeName(S.Context) << Ex->getType()
+          << Ex->getSourceRange(),
+        getLocationOfByte(CS.getStart()),
+        /*IsStringLocation*/true,
+        getSpecifierRange(startSpecifier, specifierLen),
+        FixItHint::CreateReplacement(
+          getSpecifierRange(startSpecifier, specifierLen),
+          os.str()));
+    }
+    else {
+      EmitFormatDiagnostic(
+        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
+          << ATR.getRepresentativeTypeName(S.Context) << Ex->getType()
+          << getSpecifierRange(startSpecifier, specifierLen)
+          << Ex->getSourceRange(),
+        getLocationOfByte(CS.getStart()),
+        true,
+        getSpecifierRange(startSpecifier, specifierLen));
+    }
+  }
+
+  return true;
+}
+
+//===--- CHECK: Scanf format string checking ------------------------------===//
+
+namespace {  
+class CheckScanfHandler : public CheckFormatHandler {
+public:
+  CheckScanfHandler(Sema &s, const StringLiteral *fexpr,
+                    const Expr *origFormatExpr, unsigned firstDataArg,
+                    unsigned numDataArgs, bool isObjCLiteral,
+                    const char *beg, bool hasVAListArg,
+                    Expr **Args, unsigned NumArgs,
+                    unsigned formatIdx, bool inFunctionCall)
+  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
+                       numDataArgs, isObjCLiteral, beg, hasVAListArg,
+                       Args, NumArgs, formatIdx, inFunctionCall) {}
+  
+  bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS,
+                            const char *startSpecifier,
+                            unsigned specifierLen);
+  
+  bool HandleInvalidScanfConversionSpecifier(
+          const analyze_scanf::ScanfSpecifier &FS,
+          const char *startSpecifier,
+          unsigned specifierLen);
+
+  void HandleIncompleteScanList(const char *start, const char *end);
+};
+}
+
+void CheckScanfHandler::HandleIncompleteScanList(const char *start,
+                                                 const char *end) {
+  EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_scanlist_incomplete),
+                       getLocationOfByte(end), /*IsStringLocation*/true,
+                       getSpecifierRange(start, end - start));
+}
+
+bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier(
+                                        const analyze_scanf::ScanfSpecifier &FS,
+                                        const char *startSpecifier,
+                                        unsigned specifierLen) {
+
+  const analyze_scanf::ScanfConversionSpecifier &CS =
+    FS.getConversionSpecifier();
+
+  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
+                                          getLocationOfByte(CS.getStart()),
+                                          startSpecifier, specifierLen,
+                                          CS.getStart(), CS.getLength());
+}
+
+bool CheckScanfHandler::HandleScanfSpecifier(
+                                       const analyze_scanf::ScanfSpecifier &FS,
+                                       const char *startSpecifier,
+                                       unsigned specifierLen) {
+  
+  using namespace analyze_scanf;
+  using namespace analyze_format_string;  
+
+  const ScanfConversionSpecifier &CS = FS.getConversionSpecifier();
+
+  // Handle case where '%' and '*' don't consume an argument.  These shouldn't
+  // be used to decide if we are using positional arguments consistently.
+  if (FS.consumesDataArgument()) {
+    if (atFirstArg) {
+      atFirstArg = false;
+      usesPositionalArgs = FS.usesPositionalArg();
+    }
+    else if (usesPositionalArgs != FS.usesPositionalArg()) {
+      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
+                                        startSpecifier, specifierLen);
+      return false;
+    }
+  }
+  
+  // Check if the field with is non-zero.
+  const OptionalAmount &Amt = FS.getFieldWidth();
+  if (Amt.getHowSpecified() == OptionalAmount::Constant) {
+    if (Amt.getConstantAmount() == 0) {
+      const CharSourceRange &R = getSpecifierRange(Amt.getStart(),
+                                                   Amt.getConstantLength());
+      EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_nonzero_width),
+                           getLocationOfByte(Amt.getStart()),
+                           /*IsStringLocation*/true, R,
+                           FixItHint::CreateRemoval(R));
+    }
+  }
+  
+  if (!FS.consumesDataArgument()) {
+    // FIXME: Technically specifying a precision or field width here
+    // makes no sense.  Worth issuing a warning at some point.
+    return true;
+  }
+  
+  // Consume the argument.
+  unsigned argIndex = FS.getArgIndex();
+  if (argIndex < NumDataArgs) {
+      // The check to see if the argIndex is valid will come later.
+      // We set the bit here because we may exit early from this
+      // function if we encounter some other error.
+    CoveredArgs.set(argIndex);
+  }
+  
+  // Check the length modifier is valid with the given conversion specifier.
+  const LengthModifier &LM = FS.getLengthModifier();
+  if (!FS.hasValidLengthModifier()) {
+    const CharSourceRange &R = getSpecifierRange(LM.getStart(), LM.getLength());
+    EmitFormatDiagnostic(S.PDiag(diag::warn_format_nonsensical_length)
+                         << LM.toString() << CS.toString()
+                         << getSpecifierRange(startSpecifier, specifierLen),
+                         getLocationOfByte(LM.getStart()),
+                         /*IsStringLocation*/true, R,
+                         FixItHint::CreateRemoval(R));
+  }
+
+  if (!FS.hasStandardLengthModifier())
+    HandleNonStandardLengthModifier(LM, startSpecifier, specifierLen);
+  if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
+    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
+  if (!FS.hasStandardLengthConversionCombination())
+    HandleNonStandardConversionSpecification(LM, CS, startSpecifier,
+                                             specifierLen);
+
+  // The remaining checks depend on the data arguments.
+  if (HasVAListArg)
+    return true;
+  
+  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
+    return false;
+  
+  // Check that the argument type matches the format specifier.
+  const Expr *Ex = getDataArg(argIndex);
+  const analyze_scanf::ScanfArgTypeResult &ATR = FS.getArgType(S.Context);
+  if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) {
+    ScanfSpecifier fixedFS = FS;
+    bool success = fixedFS.fixType(Ex->getType(), S.getLangOpts(),
+                                   S.Context);
+
+    if (success) {
+      // Get the fix string from the fixed format specifier.
+      SmallString<128> buf;
+      llvm::raw_svector_ostream os(buf);
+      fixedFS.toString(os);
+
+      EmitFormatDiagnostic(
+        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
+          << ATR.getRepresentativeTypeName(S.Context) << Ex->getType()
+          << Ex->getSourceRange(),
+        getLocationOfByte(CS.getStart()),
+        /*IsStringLocation*/true,
+        getSpecifierRange(startSpecifier, specifierLen),
+        FixItHint::CreateReplacement(
+          getSpecifierRange(startSpecifier, specifierLen),
+          os.str()));
+    } else {
+      EmitFormatDiagnostic(
+        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
+          << ATR.getRepresentativeTypeName(S.Context) << Ex->getType()
+          << Ex->getSourceRange(),
+        getLocationOfByte(CS.getStart()),
+        /*IsStringLocation*/true,
+        getSpecifierRange(startSpecifier, specifierLen));
+    }
+  }
+
+  return true;
+}
+
+void Sema::CheckFormatString(const StringLiteral *FExpr,
+                             const Expr *OrigFormatExpr,
+                             Expr **Args, unsigned NumArgs,
+                             bool HasVAListArg, unsigned format_idx,
+                             unsigned firstDataArg, FormatStringType Type,
+                             bool inFunctionCall) {
+  
+  // CHECK: is the format string a wide literal?
+  if (!FExpr->isAscii()) {
+    CheckFormatHandler::EmitFormatDiagnostic(
+      *this, inFunctionCall, Args[format_idx],
+      PDiag(diag::warn_format_string_is_wide_literal), FExpr->getLocStart(),
+      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
+    return;
+  }
+  
+  // Str - The format string.  NOTE: this is NOT null-terminated!
+  StringRef StrRef = FExpr->getString();
+  const char *Str = StrRef.data();
+  unsigned StrLen = StrRef.size();
+  const unsigned numDataArgs = NumArgs - firstDataArg;
+  
+  // CHECK: empty format string?
+  if (StrLen == 0 && numDataArgs > 0) {
+    CheckFormatHandler::EmitFormatDiagnostic(
+      *this, inFunctionCall, Args[format_idx],
+      PDiag(diag::warn_empty_format_string), FExpr->getLocStart(),
+      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
+    return;
+  }
+  
+  if (Type == FST_Printf || Type == FST_NSString) {
+    CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg,
+                         numDataArgs, isa<ObjCStringLiteral>(OrigFormatExpr),
+                         Str, HasVAListArg, Args, NumArgs, format_idx,
+                         inFunctionCall);
+  
+    if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen,
+                                                  getLangOpts()))
+      H.DoneProcessing();
+  } else if (Type == FST_Scanf) {
+    CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg,
+                        numDataArgs, isa<ObjCStringLiteral>(OrigFormatExpr),
+                        Str, HasVAListArg, Args, NumArgs, format_idx,
+                        inFunctionCall);
+    
+    if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen,
+                                                 getLangOpts()))
+      H.DoneProcessing();
+  } // TODO: handle other formats
+}
+
+//===--- CHECK: Standard memory functions ---------------------------------===//
+
+/// \brief Determine whether the given type is a dynamic class type (e.g.,
+/// whether it has a vtable).
+static bool isDynamicClassType(QualType T) {
+  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl())
+    if (CXXRecordDecl *Definition = Record->getDefinition())
+      if (Definition->isDynamicClass())
+        return true;
+  
+  return false;
+}
+
+/// \brief If E is a sizeof expression, returns its argument expression,
+/// otherwise returns NULL.
+static const Expr *getSizeOfExprArg(const Expr* E) {
+  if (const UnaryExprOrTypeTraitExpr *SizeOf =
+      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
+    if (SizeOf->getKind() == clang::UETT_SizeOf && !SizeOf->isArgumentType())
+      return SizeOf->getArgumentExpr()->IgnoreParenImpCasts();
+
+  return 0;
+}
+
+/// \brief If E is a sizeof expression, returns its argument type.
+static QualType getSizeOfArgType(const Expr* E) {
+  if (const UnaryExprOrTypeTraitExpr *SizeOf =
+      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
+    if (SizeOf->getKind() == clang::UETT_SizeOf)
+      return SizeOf->getTypeOfArgument();
+
+  return QualType();
+}
+
+/// \brief Check for dangerous or invalid arguments to memset().
+///
+/// This issues warnings on known problematic, dangerous or unspecified
+/// arguments to the standard 'memset', 'memcpy', 'memmove', and 'memcmp'
+/// function calls.
+///
+/// \param Call The call expression to diagnose.
+void Sema::CheckMemaccessArguments(const CallExpr *Call,
+                                   unsigned BId,
+                                   IdentifierInfo *FnName) {
+  assert(BId != 0);
+
+  // It is possible to have a non-standard definition of memset.  Validate
+  // we have enough arguments, and if not, abort further checking.
+  unsigned ExpectedNumArgs = (BId == Builtin::BIstrndup ? 2 : 3);
+  if (Call->getNumArgs() < ExpectedNumArgs)
+    return;
+
+  unsigned LastArg = (BId == Builtin::BImemset ||
+                      BId == Builtin::BIstrndup ? 1 : 2);
+  unsigned LenArg = (BId == Builtin::BIstrndup ? 1 : 2);
+  const Expr *LenExpr = Call->getArg(LenArg)->IgnoreParenImpCasts();
+
+  // We have special checking when the length is a sizeof expression.
+  QualType SizeOfArgTy = getSizeOfArgType(LenExpr);
+  const Expr *SizeOfArg = getSizeOfExprArg(LenExpr);
+  llvm::FoldingSetNodeID SizeOfArgID;
+
+  for (unsigned ArgIdx = 0; ArgIdx != LastArg; ++ArgIdx) {
+    const Expr *Dest = Call->getArg(ArgIdx)->IgnoreParenImpCasts();
+    SourceRange ArgRange = Call->getArg(ArgIdx)->getSourceRange();
+
+    QualType DestTy = Dest->getType();
+    if (const PointerType *DestPtrTy = DestTy->getAs<PointerType>()) {
+      QualType PointeeTy = DestPtrTy->getPointeeType();
+
+      // Never warn about void type pointers. This can be used to suppress
+      // false positives.
+      if (PointeeTy->isVoidType())
+        continue;
+
+      // Catch "memset(p, 0, sizeof(p))" -- needs to be sizeof(*p). Do this by
+      // actually comparing the expressions for equality. Because computing the
+      // expression IDs can be expensive, we only do this if the diagnostic is
+      // enabled.
+      if (SizeOfArg &&
+          Diags.getDiagnosticLevel(diag::warn_sizeof_pointer_expr_memaccess,
+                                   SizeOfArg->getExprLoc())) {
+        // We only compute IDs for expressions if the warning is enabled, and
+        // cache the sizeof arg's ID.
+        if (SizeOfArgID == llvm::FoldingSetNodeID())
+          SizeOfArg->Profile(SizeOfArgID, Context, true);
+        llvm::FoldingSetNodeID DestID;
+        Dest->Profile(DestID, Context, true);
+        if (DestID == SizeOfArgID) {
+          // TODO: For strncpy() and friends, this could suggest sizeof(dst)
+          //       over sizeof(src) as well.
+          unsigned ActionIdx = 0; // Default is to suggest dereferencing.
+          if (const UnaryOperator *UnaryOp = dyn_cast<UnaryOperator>(Dest))
+            if (UnaryOp->getOpcode() == UO_AddrOf)
+              ActionIdx = 1; // If its an address-of operator, just remove it.
+          if (Context.getTypeSize(PointeeTy) == Context.getCharWidth())
+            ActionIdx = 2; // If the pointee's size is sizeof(char),
+                           // suggest an explicit length.
+          unsigned DestSrcSelect =
+            (BId == Builtin::BIstrndup ? 1 : ArgIdx);
+          DiagRuntimeBehavior(SizeOfArg->getExprLoc(), Dest,
+                              PDiag(diag::warn_sizeof_pointer_expr_memaccess)
+                                << FnName << DestSrcSelect << ActionIdx
+                                << Dest->getSourceRange()
+                                << SizeOfArg->getSourceRange());
+          break;
+        }
+      }
+
+      // Also check for cases where the sizeof argument is the exact same
+      // type as the memory argument, and where it points to a user-defined
+      // record type.
+      if (SizeOfArgTy != QualType()) {
+        if (PointeeTy->isRecordType() &&
+            Context.typesAreCompatible(SizeOfArgTy, DestTy)) {
+          DiagRuntimeBehavior(LenExpr->getExprLoc(), Dest,
+                              PDiag(diag::warn_sizeof_pointer_type_memaccess)
+                                << FnName << SizeOfArgTy << ArgIdx
+                                << PointeeTy << Dest->getSourceRange()
+                                << LenExpr->getSourceRange());
+          break;
+        }
+      }
+
+      // Always complain about dynamic classes.
+      if (isDynamicClassType(PointeeTy)) {
+
+        unsigned OperationType = 0;
+        // "overwritten" if we're warning about the destination for any call
+        // but memcmp; otherwise a verb appropriate to the call.
+        if (ArgIdx != 0 || BId == Builtin::BImemcmp) {
+          if (BId == Builtin::BImemcpy)
+            OperationType = 1;
+          else if(BId == Builtin::BImemmove)
+            OperationType = 2;
+          else if (BId == Builtin::BImemcmp)
+            OperationType = 3;
+        }
+          
+        DiagRuntimeBehavior(
+          Dest->getExprLoc(), Dest,
+          PDiag(diag::warn_dyn_class_memaccess)
+            << (BId == Builtin::BImemcmp ? ArgIdx + 2 : ArgIdx)
+            << FnName << PointeeTy
+            << OperationType
+            << Call->getCallee()->getSourceRange());
+      } else if (PointeeTy.hasNonTrivialObjCLifetime() &&
+               BId != Builtin::BImemset)
+        DiagRuntimeBehavior(
+          Dest->getExprLoc(), Dest,
+          PDiag(diag::warn_arc_object_memaccess)
+            << ArgIdx << FnName << PointeeTy
+            << Call->getCallee()->getSourceRange());
+      else
+        continue;
+
+      DiagRuntimeBehavior(
+        Dest->getExprLoc(), Dest,
+        PDiag(diag::note_bad_memaccess_silence)
+          << FixItHint::CreateInsertion(ArgRange.getBegin(), "(void*)"));
+      break;
+    }
+  }
+}
+
+// A little helper routine: ignore addition and subtraction of integer literals.
+// This intentionally does not ignore all integer constant expressions because
+// we don't want to remove sizeof().
+static const Expr *ignoreLiteralAdditions(const Expr *Ex, ASTContext &Ctx) {
+  Ex = Ex->IgnoreParenCasts();
+
+  for (;;) {
+    const BinaryOperator * BO = dyn_cast<BinaryOperator>(Ex);
+    if (!BO || !BO->isAdditiveOp())
+      break;
+
+    const Expr *RHS = BO->getRHS()->IgnoreParenCasts();
+    const Expr *LHS = BO->getLHS()->IgnoreParenCasts();
+    
+    if (isa<IntegerLiteral>(RHS))
+      Ex = LHS;
+    else if (isa<IntegerLiteral>(LHS))
+      Ex = RHS;
+    else
+      break;
+  }
+
+  return Ex;
+}
+
+// Warn if the user has made the 'size' argument to strlcpy or strlcat
+// be the size of the source, instead of the destination.
+void Sema::CheckStrlcpycatArguments(const CallExpr *Call,
+                                    IdentifierInfo *FnName) {
+
+  // Don't crash if the user has the wrong number of arguments
+  if (Call->getNumArgs() != 3)
+    return;
+
+  const Expr *SrcArg = ignoreLiteralAdditions(Call->getArg(1), Context);
+  const Expr *SizeArg = ignoreLiteralAdditions(Call->getArg(2), Context);
+  const Expr *CompareWithSrc = NULL;
+  
+  // Look for 'strlcpy(dst, x, sizeof(x))'
+  if (const Expr *Ex = getSizeOfExprArg(SizeArg))
+    CompareWithSrc = Ex;
+  else {
+    // Look for 'strlcpy(dst, x, strlen(x))'
+    if (const CallExpr *SizeCall = dyn_cast<CallExpr>(SizeArg)) {
+      if (SizeCall->isBuiltinCall() == Builtin::BIstrlen
+          && SizeCall->getNumArgs() == 1)
+        CompareWithSrc = ignoreLiteralAdditions(SizeCall->getArg(0), Context);
+    }
+  }
+
+  if (!CompareWithSrc)
+    return;
+
+  // Determine if the argument to sizeof/strlen is equal to the source
+  // argument.  In principle there's all kinds of things you could do
+  // here, for instance creating an == expression and evaluating it with
+  // EvaluateAsBooleanCondition, but this uses a more direct technique:
+  const DeclRefExpr *SrcArgDRE = dyn_cast<DeclRefExpr>(SrcArg);
+  if (!SrcArgDRE)
+    return;
+  
+  const DeclRefExpr *CompareWithSrcDRE = dyn_cast<DeclRefExpr>(CompareWithSrc);
+  if (!CompareWithSrcDRE || 
+      SrcArgDRE->getDecl() != CompareWithSrcDRE->getDecl())
+    return;
+  
+  const Expr *OriginalSizeArg = Call->getArg(2);
+  Diag(CompareWithSrcDRE->getLocStart(), diag::warn_strlcpycat_wrong_size)
+    << OriginalSizeArg->getSourceRange() << FnName;
+  
+  // Output a FIXIT hint if the destination is an array (rather than a
+  // pointer to an array).  This could be enhanced to handle some
+  // pointers if we know the actual size, like if DstArg is 'array+2'
+  // we could say 'sizeof(array)-2'.
+  const Expr *DstArg = Call->getArg(0)->IgnoreParenImpCasts();
+  QualType DstArgTy = DstArg->getType();
+  
+  // Only handle constant-sized or VLAs, but not flexible members.
+  if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(DstArgTy)) {
+    // Only issue the FIXIT for arrays of size > 1.
+    if (CAT->getSize().getSExtValue() <= 1)
+      return;
+  } else if (!DstArgTy->isVariableArrayType()) {
+    return;
+  }
+
+  SmallString<128> sizeString;
+  llvm::raw_svector_ostream OS(sizeString);
+  OS << "sizeof(";
+  DstArg->printPretty(OS, Context, 0, getPrintingPolicy());
+  OS << ")";
+  
+  Diag(OriginalSizeArg->getLocStart(), diag::note_strlcpycat_wrong_size)
+    << FixItHint::CreateReplacement(OriginalSizeArg->getSourceRange(),
+                                    OS.str());
+}
+
+/// Check if two expressions refer to the same declaration.
+static bool referToTheSameDecl(const Expr *E1, const Expr *E2) {
+  if (const DeclRefExpr *D1 = dyn_cast_or_null<DeclRefExpr>(E1))
+    if (const DeclRefExpr *D2 = dyn_cast_or_null<DeclRefExpr>(E2))
+      return D1->getDecl() == D2->getDecl();
+  return false;
+}
+
+static const Expr *getStrlenExprArg(const Expr *E) {
+  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
+    const FunctionDecl *FD = CE->getDirectCallee();
+    if (!FD || FD->getMemoryFunctionKind() != Builtin::BIstrlen)
+      return 0;
+    return CE->getArg(0)->IgnoreParenCasts();
+  }
+  return 0;
+}
+
+// Warn on anti-patterns as the 'size' argument to strncat.
+// The correct size argument should look like following:
+//   strncat(dst, src, sizeof(dst) - strlen(dest) - 1);
+void Sema::CheckStrncatArguments(const CallExpr *CE,
+                                 IdentifierInfo *FnName) {
+  // Don't crash if the user has the wrong number of arguments.
+  if (CE->getNumArgs() < 3)
+    return;
+  const Expr *DstArg = CE->getArg(0)->IgnoreParenCasts();
+  const Expr *SrcArg = CE->getArg(1)->IgnoreParenCasts();
+  const Expr *LenArg = CE->getArg(2)->IgnoreParenCasts();
+
+  // Identify common expressions, which are wrongly used as the size argument
+  // to strncat and may lead to buffer overflows.
+  unsigned PatternType = 0;
+  if (const Expr *SizeOfArg = getSizeOfExprArg(LenArg)) {
+    // - sizeof(dst)
+    if (referToTheSameDecl(SizeOfArg, DstArg))
+      PatternType = 1;
+    // - sizeof(src)
+    else if (referToTheSameDecl(SizeOfArg, SrcArg))
+      PatternType = 2;
+  } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(LenArg)) {
+    if (BE->getOpcode() == BO_Sub) {
+      const Expr *L = BE->getLHS()->IgnoreParenCasts();
+      const Expr *R = BE->getRHS()->IgnoreParenCasts();
+      // - sizeof(dst) - strlen(dst)
+      if (referToTheSameDecl(DstArg, getSizeOfExprArg(L)) &&
+          referToTheSameDecl(DstArg, getStrlenExprArg(R)))
+        PatternType = 1;
+      // - sizeof(src) - (anything)
+      else if (referToTheSameDecl(SrcArg, getSizeOfExprArg(L)))
+        PatternType = 2;
+    }
+  }
+
+  if (PatternType == 0)
+    return;
+
+  // Generate the diagnostic.
+  SourceLocation SL = LenArg->getLocStart();
+  SourceRange SR = LenArg->getSourceRange();
+  SourceManager &SM  = PP.getSourceManager();
+
+  // If the function is defined as a builtin macro, do not show macro expansion.
+  if (SM.isMacroArgExpansion(SL)) {
+    SL = SM.getSpellingLoc(SL);
+    SR = SourceRange(SM.getSpellingLoc(SR.getBegin()),
+                     SM.getSpellingLoc(SR.getEnd()));
+  }
+
+  if (PatternType == 1)
+    Diag(SL, diag::warn_strncat_large_size) << SR;
+  else
+    Diag(SL, diag::warn_strncat_src_size) << SR;
+
+  // Output a FIXIT hint if the destination is an array (rather than a
+  // pointer to an array).  This could be enhanced to handle some
+  // pointers if we know the actual size, like if DstArg is 'array+2'
+  // we could say 'sizeof(array)-2'.
+  QualType DstArgTy = DstArg->getType();
+
+  // Only handle constant-sized or VLAs, but not flexible members.
+  if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(DstArgTy)) {
+    // Only issue the FIXIT for arrays of size > 1.
+    if (CAT->getSize().getSExtValue() <= 1)
+      return;
+  } else if (!DstArgTy->isVariableArrayType()) {
+    return;
+  }
+
+  SmallString<128> sizeString;
+  llvm::raw_svector_ostream OS(sizeString);
+  OS << "sizeof(";
+  DstArg->printPretty(OS, Context, 0, getPrintingPolicy());
+  OS << ") - ";
+  OS << "strlen(";
+  DstArg->printPretty(OS, Context, 0, getPrintingPolicy());
+  OS << ") - 1";
+
+  Diag(SL, diag::note_strncat_wrong_size)
+    << FixItHint::CreateReplacement(SR, OS.str());
+}
+
+//===--- CHECK: Return Address of Stack Variable --------------------------===//
+
+static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars);
+static Expr *EvalAddr(Expr* E, SmallVectorImpl<DeclRefExpr *> &refVars);
+
+/// CheckReturnStackAddr - Check if a return statement returns the address
+///   of a stack variable.
+void
+Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType,
+                           SourceLocation ReturnLoc) {
+
+  Expr *stackE = 0;
+  SmallVector<DeclRefExpr *, 8> refVars;
+
+  // Perform checking for returned stack addresses, local blocks,
+  // label addresses or references to temporaries.
+  if (lhsType->isPointerType() ||
+      (!getLangOpts().ObjCAutoRefCount && lhsType->isBlockPointerType())) {
+    stackE = EvalAddr(RetValExp, refVars);
+  } else if (lhsType->isReferenceType()) {
+    stackE = EvalVal(RetValExp, refVars);
+  }
+
+  if (stackE == 0)
+    return; // Nothing suspicious was found.
+
+  SourceLocation diagLoc;
+  SourceRange diagRange;
+  if (refVars.empty()) {
+    diagLoc = stackE->getLocStart();
+    diagRange = stackE->getSourceRange();
+  } else {
+    // We followed through a reference variable. 'stackE' contains the
+    // problematic expression but we will warn at the return statement pointing
+    // at the reference variable. We will later display the "trail" of
+    // reference variables using notes.
+    diagLoc = refVars[0]->getLocStart();
+    diagRange = refVars[0]->getSourceRange();
+  }
+
+  if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(stackE)) { //address of local var.
+    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_stack_ref
+                                             : diag::warn_ret_stack_addr)
+     << DR->getDecl()->getDeclName() << diagRange;
+  } else if (isa<BlockExpr>(stackE)) { // local block.
+    Diag(diagLoc, diag::err_ret_local_block) << diagRange;
+  } else if (isa<AddrLabelExpr>(stackE)) { // address of label.
+    Diag(diagLoc, diag::warn_ret_addr_label) << diagRange;
+  } else { // local temporary.
+    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_local_temp_ref
+                                             : diag::warn_ret_local_temp_addr)
+     << diagRange;
+  }
+
+  // Display the "trail" of reference variables that we followed until we
+  // found the problematic expression using notes.
+  for (unsigned i = 0, e = refVars.size(); i != e; ++i) {
+    VarDecl *VD = cast<VarDecl>(refVars[i]->getDecl());
+    // If this var binds to another reference var, show the range of the next
+    // var, otherwise the var binds to the problematic expression, in which case
+    // show the range of the expression.
+    SourceRange range = (i < e-1) ? refVars[i+1]->getSourceRange()
+                                  : stackE->getSourceRange();
+    Diag(VD->getLocation(), diag::note_ref_var_local_bind)
+      << VD->getDeclName() << range;
+  }
+}
+
+/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that
+///  check if the expression in a return statement evaluates to an address
+///  to a location on the stack, a local block, an address of a label, or a
+///  reference to local temporary. The recursion is used to traverse the
+///  AST of the return expression, with recursion backtracking when we
+///  encounter a subexpression that (1) clearly does not lead to one of the
+///  above problematic expressions (2) is something we cannot determine leads to
+///  a problematic expression based on such local checking.
+///
+///  Both EvalAddr and EvalVal follow through reference variables to evaluate
+///  the expression that they point to. Such variables are added to the
+///  'refVars' vector so that we know what the reference variable "trail" was.
+///
+///  EvalAddr processes expressions that are pointers that are used as
+///  references (and not L-values).  EvalVal handles all other values.
+///  At the base case of the recursion is a check for the above problematic
+///  expressions.
+///
+///  This implementation handles:
+///
+///   * pointer-to-pointer casts
+///   * implicit conversions from array references to pointers
+///   * taking the address of fields
+///   * arbitrary interplay between "&" and "*" operators
+///   * pointer arithmetic from an address of a stack variable
+///   * taking the address of an array element where the array is on the stack
+static Expr *EvalAddr(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars) {
+  if (E->isTypeDependent())
+      return NULL;
+
+  // We should only be called for evaluating pointer expressions.
+  assert((E->getType()->isAnyPointerType() ||
+          E->getType()->isBlockPointerType() ||
+          E->getType()->isObjCQualifiedIdType()) &&
+         "EvalAddr only works on pointers");
+
+  E = E->IgnoreParens();
+
+  // Our "symbolic interpreter" is just a dispatch off the currently
+  // viewed AST node.  We then recursively traverse the AST by calling
+  // EvalAddr and EvalVal appropriately.
+  switch (E->getStmtClass()) {
+  case Stmt::DeclRefExprClass: {
+    DeclRefExpr *DR = cast<DeclRefExpr>(E);
+
+    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl()))
+      // If this is a reference variable, follow through to the expression that
+      // it points to.
+      if (V->hasLocalStorage() &&
+          V->getType()->isReferenceType() && V->hasInit()) {
+        // Add the reference variable to the "trail".
+        refVars.push_back(DR);
+        return EvalAddr(V->getInit(), refVars);
+      }
+
+    return NULL;
+  }
+
+  case Stmt::UnaryOperatorClass: {
+    // The only unary operator that make sense to handle here
+    // is AddrOf.  All others don't make sense as pointers.
+    UnaryOperator *U = cast<UnaryOperator>(E);
+
+    if (U->getOpcode() == UO_AddrOf)
+      return EvalVal(U->getSubExpr(), refVars);
+    else
+      return NULL;
+  }
+
+  case Stmt::BinaryOperatorClass: {
+    // Handle pointer arithmetic.  All other binary operators are not valid
+    // in this context.
+    BinaryOperator *B = cast<BinaryOperator>(E);
+    BinaryOperatorKind op = B->getOpcode();
+
+    if (op != BO_Add && op != BO_Sub)
+      return NULL;
+
+    Expr *Base = B->getLHS();
+
+    // Determine which argument is the real pointer base.  It could be
+    // the RHS argument instead of the LHS.
+    if (!Base->getType()->isPointerType()) Base = B->getRHS();
+
+    assert (Base->getType()->isPointerType());
+    return EvalAddr(Base, refVars);
+  }
+
+  // For conditional operators we need to see if either the LHS or RHS are
+  // valid DeclRefExpr*s.  If one of them is valid, we return it.
+  case Stmt::ConditionalOperatorClass: {
+    ConditionalOperator *C = cast<ConditionalOperator>(E);
+
+    // Handle the GNU extension for missing LHS.
+    if (Expr *lhsExpr = C->getLHS()) {
+    // In C++, we can have a throw-expression, which has 'void' type.
+      if (!lhsExpr->getType()->isVoidType())
+        if (Expr* LHS = EvalAddr(lhsExpr, refVars))
+          return LHS;
+    }
+
+    // In C++, we can have a throw-expression, which has 'void' type.
+    if (C->getRHS()->getType()->isVoidType())
+      return NULL;
+
+    return EvalAddr(C->getRHS(), refVars);
+  }
+  
+  case Stmt::BlockExprClass:
+    if (cast<BlockExpr>(E)->getBlockDecl()->hasCaptures())
+      return E; // local block.
+    return NULL;
+
+  case Stmt::AddrLabelExprClass:
+    return E; // address of label.
+
+  case Stmt::ExprWithCleanupsClass:
+    return EvalAddr(cast<ExprWithCleanups>(E)->getSubExpr(), refVars);
+
+  // For casts, we need to handle conversions from arrays to
+  // pointer values, and pointer-to-pointer conversions.
+  case Stmt::ImplicitCastExprClass:
+  case Stmt::CStyleCastExprClass:
+  case Stmt::CXXFunctionalCastExprClass:
+  case Stmt::ObjCBridgedCastExprClass:
+  case Stmt::CXXStaticCastExprClass:
+  case Stmt::CXXDynamicCastExprClass:
+  case Stmt::CXXConstCastExprClass:
+  case Stmt::CXXReinterpretCastExprClass: {
+    Expr* SubExpr = cast<CastExpr>(E)->getSubExpr();
+    switch (cast<CastExpr>(E)->getCastKind()) {
+    case CK_BitCast:
+    case CK_LValueToRValue:
+    case CK_NoOp:
+    case CK_BaseToDerived:
+    case CK_DerivedToBase:
+    case CK_UncheckedDerivedToBase:
+    case CK_Dynamic:
+    case CK_CPointerToObjCPointerCast:
+    case CK_BlockPointerToObjCPointerCast:
+    case CK_AnyPointerToBlockPointerCast:
+      return EvalAddr(SubExpr, refVars);
+
+    case CK_ArrayToPointerDecay:
+      return EvalVal(SubExpr, refVars);
+
+    default:
+      return 0;
+    }
+  }
+
+  case Stmt::MaterializeTemporaryExprClass:
+    if (Expr *Result = EvalAddr(
+                         cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
+                                refVars))
+      return Result;
+      
+    return E;
+      
+  // Everything else: we simply don't reason about them.
+  default:
+    return NULL;
+  }
+}
+
+
+///  EvalVal - This function is complements EvalAddr in the mutual recursion.
+///   See the comments for EvalAddr for more details.
+static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars) {
+do {
+  // We should only be called for evaluating non-pointer expressions, or
+  // expressions with a pointer type that are not used as references but instead
+  // are l-values (e.g., DeclRefExpr with a pointer type).
+
+  // Our "symbolic interpreter" is just a dispatch off the currently
+  // viewed AST node.  We then recursively traverse the AST by calling
+  // EvalAddr and EvalVal appropriately.
+
+  E = E->IgnoreParens();
+  switch (E->getStmtClass()) {
+  case Stmt::ImplicitCastExprClass: {
+    ImplicitCastExpr *IE = cast<ImplicitCastExpr>(E);
+    if (IE->getValueKind() == VK_LValue) {
+      E = IE->getSubExpr();
+      continue;
+    }
+    return NULL;
+  }
+
+  case Stmt::ExprWithCleanupsClass:
+    return EvalVal(cast<ExprWithCleanups>(E)->getSubExpr(), refVars);
+
+  case Stmt::DeclRefExprClass: {
+    // When we hit a DeclRefExpr we are looking at code that refers to a
+    // variable's name. If it's not a reference variable we check if it has
+    // local storage within the function, and if so, return the expression.
+    DeclRefExpr *DR = cast<DeclRefExpr>(E);
+
+    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl()))
+      if (V->hasLocalStorage()) {
+        if (!V->getType()->isReferenceType())
+          return DR;
+
+        // Reference variable, follow through to the expression that
+        // it points to.
+        if (V->hasInit()) {
+          // Add the reference variable to the "trail".
+          refVars.push_back(DR);
+          return EvalVal(V->getInit(), refVars);
+        }
+      }
+
+    return NULL;
+  }
+
+  case Stmt::UnaryOperatorClass: {
+    // The only unary operator that make sense to handle here
+    // is Deref.  All others don't resolve to a "name."  This includes
+    // handling all sorts of rvalues passed to a unary operator.
+    UnaryOperator *U = cast<UnaryOperator>(E);
+
+    if (U->getOpcode() == UO_Deref)
+      return EvalAddr(U->getSubExpr(), refVars);
+
+    return NULL;
+  }
+
+  case Stmt::ArraySubscriptExprClass: {
+    // Array subscripts are potential references to data on the stack.  We
+    // retrieve the DeclRefExpr* for the array variable if it indeed
+    // has local storage.
+    return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase(), refVars);
+  }
+
+  case Stmt::ConditionalOperatorClass: {
+    // For conditional operators we need to see if either the LHS or RHS are
+    // non-NULL Expr's.  If one is non-NULL, we return it.
+    ConditionalOperator *C = cast<ConditionalOperator>(E);
+
+    // Handle the GNU extension for missing LHS.
+    if (Expr *lhsExpr = C->getLHS())
+      if (Expr *LHS = EvalVal(lhsExpr, refVars))
+        return LHS;
+
+    return EvalVal(C->getRHS(), refVars);
+  }
+
+  // Accesses to members are potential references to data on the stack.
+  case Stmt::MemberExprClass: {
+    MemberExpr *M = cast<MemberExpr>(E);
+
+    // Check for indirect access.  We only want direct field accesses.
+    if (M->isArrow())
+      return NULL;
+
+    // Check whether the member type is itself a reference, in which case
+    // we're not going to refer to the member, but to what the member refers to.
+    if (M->getMemberDecl()->getType()->isReferenceType())
+      return NULL;
+
+    return EvalVal(M->getBase(), refVars);
+  }
+
+  case Stmt::MaterializeTemporaryExprClass:
+    if (Expr *Result = EvalVal(
+                          cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
+                               refVars))
+      return Result;
+      
+    return E;
+
+  default:
+    // Check that we don't return or take the address of a reference to a
+    // temporary. This is only useful in C++.
+    if (!E->isTypeDependent() && E->isRValue())
+      return E;
+
+    // Everything else: we simply don't reason about them.
+    return NULL;
+  }
+} while (true);
+}
+
+//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===//
+
+/// Check for comparisons of floating point operands using != and ==.
+/// Issue a warning if these are no self-comparisons, as they are not likely
+/// to do what the programmer intended.
+void Sema::CheckFloatComparison(SourceLocation Loc, Expr* LHS, Expr *RHS) {
+  bool EmitWarning = true;
+
+  Expr* LeftExprSansParen = LHS->IgnoreParenImpCasts();
+  Expr* RightExprSansParen = RHS->IgnoreParenImpCasts();
+
+  // Special case: check for x == x (which is OK).
+  // Do not emit warnings for such cases.
+  if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen))
+    if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen))
+      if (DRL->getDecl() == DRR->getDecl())
+        EmitWarning = false;
+
+
+  // Special case: check for comparisons against literals that can be exactly
+  //  represented by APFloat.  In such cases, do not emit a warning.  This
+  //  is a heuristic: often comparison against such literals are used to
+  //  detect if a value in a variable has not changed.  This clearly can
+  //  lead to false negatives.
+  if (EmitWarning) {
+    if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) {
+      if (FLL->isExact())
+        EmitWarning = false;
+    } else
+      if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){
+        if (FLR->isExact())
+          EmitWarning = false;
+    }
+  }
+
+  // Check for comparisons with builtin types.
+  if (EmitWarning)
+    if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen))
+      if (CL->isBuiltinCall())
+        EmitWarning = false;
+
+  if (EmitWarning)
+    if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen))
+      if (CR->isBuiltinCall())
+        EmitWarning = false;
+
+  // Emit the diagnostic.
+  if (EmitWarning)
+    Diag(Loc, diag::warn_floatingpoint_eq)
+      << LHS->getSourceRange() << RHS->getSourceRange();
+}
+
+//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===//
+//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===//
+
+namespace {
+
+/// Structure recording the 'active' range of an integer-valued
+/// expression.
+struct IntRange {
+  /// The number of bits active in the int.
+  unsigned Width;
+
+  /// True if the int is known not to have negative values.
+  bool NonNegative;
+
+  IntRange(unsigned Width, bool NonNegative)
+    : Width(Width), NonNegative(NonNegative)
+  {}
+
+  /// Returns the range of the bool type.
+  static IntRange forBoolType() {
+    return IntRange(1, true);
+  }
+
+  /// Returns the range of an opaque value of the given integral type.
+  static IntRange forValueOfType(ASTContext &C, QualType T) {
+    return forValueOfCanonicalType(C,
+                          T->getCanonicalTypeInternal().getTypePtr());
+  }
+
+  /// Returns the range of an opaque value of a canonical integral type.
+  static IntRange forValueOfCanonicalType(ASTContext &C, const Type *T) {
+    assert(T->isCanonicalUnqualified());
+
+    if (const VectorType *VT = dyn_cast<VectorType>(T))
+      T = VT->getElementType().getTypePtr();
+    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
+      T = CT->getElementType().getTypePtr();
+
+    // For enum types, use the known bit width of the enumerators.
+    if (const EnumType *ET = dyn_cast<EnumType>(T)) {
+      EnumDecl *Enum = ET->getDecl();
+      if (!Enum->isCompleteDefinition())
+        return IntRange(C.getIntWidth(QualType(T, 0)), false);
+
+      unsigned NumPositive = Enum->getNumPositiveBits();
+      unsigned NumNegative = Enum->getNumNegativeBits();
+
+      return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0);
+    }
+
+    const BuiltinType *BT = cast<BuiltinType>(T);
+    assert(BT->isInteger());
+
+    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
+  }
+
+  /// Returns the "target" range of a canonical integral type, i.e.
+  /// the range of values expressible in the type.
+  ///
+  /// This matches forValueOfCanonicalType except that enums have the
+  /// full range of their type, not the range of their enumerators.
+  static IntRange forTargetOfCanonicalType(ASTContext &C, const Type *T) {
+    assert(T->isCanonicalUnqualified());
+
+    if (const VectorType *VT = dyn_cast<VectorType>(T))
+      T = VT->getElementType().getTypePtr();
+    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
+      T = CT->getElementType().getTypePtr();
+    if (const EnumType *ET = dyn_cast<EnumType>(T))
+      T = C.getCanonicalType(ET->getDecl()->getIntegerType()).getTypePtr();
+
+    const BuiltinType *BT = cast<BuiltinType>(T);
+    assert(BT->isInteger());
+
+    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
+  }
+
+  /// Returns the supremum of two ranges: i.e. their conservative merge.
+  static IntRange join(IntRange L, IntRange R) {
+    return IntRange(std::max(L.Width, R.Width),
+                    L.NonNegative && R.NonNegative);
+  }
+
+  /// Returns the infinum of two ranges: i.e. their aggressive merge.
+  static IntRange meet(IntRange L, IntRange R) {
+    return IntRange(std::min(L.Width, R.Width),
+                    L.NonNegative || R.NonNegative);
+  }
+};
+
+static IntRange GetValueRange(ASTContext &C, llvm::APSInt &value,
+                              unsigned MaxWidth) {
+  if (value.isSigned() && value.isNegative())
+    return IntRange(value.getMinSignedBits(), false);
+
+  if (value.getBitWidth() > MaxWidth)
+    value = value.trunc(MaxWidth);
+
+  // isNonNegative() just checks the sign bit without considering
+  // signedness.
+  return IntRange(value.getActiveBits(), true);
+}
+
+static IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty,
+                              unsigned MaxWidth) {
+  if (result.isInt())
+    return GetValueRange(C, result.getInt(), MaxWidth);
+
+  if (result.isVector()) {
+    IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth);
+    for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) {
+      IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth);
+      R = IntRange::join(R, El);
+    }
+    return R;
+  }
+
+  if (result.isComplexInt()) {
+    IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth);
+    IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth);
+    return IntRange::join(R, I);
+  }
+
+  // This can happen with lossless casts to intptr_t of "based" lvalues.
+  // Assume it might use arbitrary bits.
+  // FIXME: The only reason we need to pass the type in here is to get
+  // the sign right on this one case.  It would be nice if APValue
+  // preserved this.
+  assert(result.isLValue() || result.isAddrLabelDiff());
+  return IntRange(MaxWidth, Ty->isUnsignedIntegerOrEnumerationType());
+}
+
+/// Pseudo-evaluate the given integer expression, estimating the
+/// range of values it might take.
+///
+/// \param MaxWidth - the width to which the value will be truncated
+static IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) {
+  E = E->IgnoreParens();
+
+  // Try a full evaluation first.
+  Expr::EvalResult result;
+  if (E->EvaluateAsRValue(result, C))
+    return GetValueRange(C, result.Val, E->getType(), MaxWidth);
+
+  // I think we only want to look through implicit casts here; if the
+  // user has an explicit widening cast, we should treat the value as
+  // being of the new, wider type.
+  if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) {
+    if (CE->getCastKind() == CK_NoOp || CE->getCastKind() == CK_LValueToRValue)
+      return GetExprRange(C, CE->getSubExpr(), MaxWidth);
+
+    IntRange OutputTypeRange = IntRange::forValueOfType(C, CE->getType());
+
+    bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast);
+
+    // Assume that non-integer casts can span the full range of the type.
+    if (!isIntegerCast)
+      return OutputTypeRange;
+
+    IntRange SubRange
+      = GetExprRange(C, CE->getSubExpr(),
+                     std::min(MaxWidth, OutputTypeRange.Width));
+
+    // Bail out if the subexpr's range is as wide as the cast type.
+    if (SubRange.Width >= OutputTypeRange.Width)
+      return OutputTypeRange;
+
+    // Otherwise, we take the smaller width, and we're non-negative if
+    // either the output type or the subexpr is.
+    return IntRange(SubRange.Width,
+                    SubRange.NonNegative || OutputTypeRange.NonNegative);
+  }
+
+  if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
+    // If we can fold the condition, just take that operand.
+    bool CondResult;
+    if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C))
+      return GetExprRange(C, CondResult ? CO->getTrueExpr()
+                                        : CO->getFalseExpr(),
+                          MaxWidth);
+
+    // Otherwise, conservatively merge.
+    IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth);
+    IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth);
+    return IntRange::join(L, R);
+  }
+
+  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
+    switch (BO->getOpcode()) {
+
+    // Boolean-valued operations are single-bit and positive.
+    case BO_LAnd:
+    case BO_LOr:
+    case BO_LT:
+    case BO_GT:
+    case BO_LE:
+    case BO_GE:
+    case BO_EQ:
+    case BO_NE:
+      return IntRange::forBoolType();
+
+    // The type of the assignments is the type of the LHS, so the RHS
+    // is not necessarily the same type.
+    case BO_MulAssign:
+    case BO_DivAssign:
+    case BO_RemAssign:
+    case BO_AddAssign:
+    case BO_SubAssign:
+    case BO_XorAssign:
+    case BO_OrAssign:
+      // TODO: bitfields?
+      return IntRange::forValueOfType(C, E->getType());
+
+    // Simple assignments just pass through the RHS, which will have
+    // been coerced to the LHS type.
+    case BO_Assign:
+      // TODO: bitfields?
+      return GetExprRange(C, BO->getRHS(), MaxWidth);
+
+    // Operations with opaque sources are black-listed.
+    case BO_PtrMemD:
+    case BO_PtrMemI:
+      return IntRange::forValueOfType(C, E->getType());
+
+    // Bitwise-and uses the *infinum* of the two source ranges.
+    case BO_And:
+    case BO_AndAssign:
+      return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth),
+                            GetExprRange(C, BO->getRHS(), MaxWidth));
+
+    // Left shift gets black-listed based on a judgement call.
+    case BO_Shl:
+      // ...except that we want to treat '1 << (blah)' as logically
+      // positive.  It's an important idiom.
+      if (IntegerLiteral *I
+            = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) {
+        if (I->getValue() == 1) {
+          IntRange R = IntRange::forValueOfType(C, E->getType());
+          return IntRange(R.Width, /*NonNegative*/ true);
+        }
+      }
+      // fallthrough
+
+    case BO_ShlAssign:
+      return IntRange::forValueOfType(C, E->getType());
+
+    // Right shift by a constant can narrow its left argument.
+    case BO_Shr:
+    case BO_ShrAssign: {
+      IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
+
+      // If the shift amount is a positive constant, drop the width by
+      // that much.
+      llvm::APSInt shift;
+      if (BO->getRHS()->isIntegerConstantExpr(shift, C) &&
+          shift.isNonNegative()) {
+        unsigned zext = shift.getZExtValue();
+        if (zext >= L.Width)
+          L.Width = (L.NonNegative ? 0 : 1);
+        else
+          L.Width -= zext;
+      }
+
+      return L;
+    }
+
+    // Comma acts as its right operand.
+    case BO_Comma:
+      return GetExprRange(C, BO->getRHS(), MaxWidth);
+
+    // Black-list pointer subtractions.
+    case BO_Sub:
+      if (BO->getLHS()->getType()->isPointerType())
+        return IntRange::forValueOfType(C, E->getType());
+      break;
+
+    // The width of a division result is mostly determined by the size
+    // of the LHS.
+    case BO_Div: {
+      // Don't 'pre-truncate' the operands.
+      unsigned opWidth = C.getIntWidth(E->getType());
+      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
+
+      // If the divisor is constant, use that.
+      llvm::APSInt divisor;
+      if (BO->getRHS()->isIntegerConstantExpr(divisor, C)) {
+        unsigned log2 = divisor.logBase2(); // floor(log_2(divisor))
+        if (log2 >= L.Width)
+          L.Width = (L.NonNegative ? 0 : 1);
+        else
+          L.Width = std::min(L.Width - log2, MaxWidth);
+        return L;
+      }
+
+      // Otherwise, just use the LHS's width.
+      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
+      return IntRange(L.Width, L.NonNegative && R.NonNegative);
+    }
+
+    // The result of a remainder can't be larger than the result of
+    // either side.
+    case BO_Rem: {
+      // Don't 'pre-truncate' the operands.
+      unsigned opWidth = C.getIntWidth(E->getType());
+      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
+      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
+
+      IntRange meet = IntRange::meet(L, R);
+      meet.Width = std::min(meet.Width, MaxWidth);
+      return meet;
+    }
+
+    // The default behavior is okay for these.
+    case BO_Mul:
+    case BO_Add:
+    case BO_Xor:
+    case BO_Or:
+      break;
+    }
+
+    // The default case is to treat the operation as if it were closed
+    // on the narrowest type that encompasses both operands.
+    IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
+    IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth);
+    return IntRange::join(L, R);
+  }
+
+  if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
+    switch (UO->getOpcode()) {
+    // Boolean-valued operations are white-listed.
+    case UO_LNot:
+      return IntRange::forBoolType();
+
+    // Operations with opaque sources are black-listed.
+    case UO_Deref:
+    case UO_AddrOf: // should be impossible
+      return IntRange::forValueOfType(C, E->getType());
+
+    default:
+      return GetExprRange(C, UO->getSubExpr(), MaxWidth);
+    }
+  }
+  
+  if (dyn_cast<OffsetOfExpr>(E)) {
+    IntRange::forValueOfType(C, E->getType());
+  }
+
+  if (FieldDecl *BitField = E->getBitField())
+    return IntRange(BitField->getBitWidthValue(C),
+                    BitField->getType()->isUnsignedIntegerOrEnumerationType());
+
+  return IntRange::forValueOfType(C, E->getType());
+}
+
+static IntRange GetExprRange(ASTContext &C, Expr *E) {
+  return GetExprRange(C, E, C.getIntWidth(E->getType()));
+}
+
+/// Checks whether the given value, which currently has the given
+/// source semantics, has the same value when coerced through the
+/// target semantics.
+static bool IsSameFloatAfterCast(const llvm::APFloat &value,
+                                 const llvm::fltSemantics &Src,
+                                 const llvm::fltSemantics &Tgt) {
+  llvm::APFloat truncated = value;
+
+  bool ignored;
+  truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored);
+  truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored);
+
+  return truncated.bitwiseIsEqual(value);
+}
+
+/// Checks whether the given value, which currently has the given
+/// source semantics, has the same value when coerced through the
+/// target semantics.
+///
+/// The value might be a vector of floats (or a complex number).
+static bool IsSameFloatAfterCast(const APValue &value,
+                                 const llvm::fltSemantics &Src,
+                                 const llvm::fltSemantics &Tgt) {
+  if (value.isFloat())
+    return IsSameFloatAfterCast(value.getFloat(), Src, Tgt);
+
+  if (value.isVector()) {
+    for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i)
+      if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt))
+        return false;
+    return true;
+  }
+
+  assert(value.isComplexFloat());
+  return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) &&
+          IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt));
+}
+
+static void AnalyzeImplicitConversions(Sema &S, Expr *E, SourceLocation CC);
+
+static bool IsZero(Sema &S, Expr *E) {
+  // Suppress cases where we are comparing against an enum constant.
+  if (const DeclRefExpr *DR =
+      dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
+    if (isa<EnumConstantDecl>(DR->getDecl()))
+      return false;
+
+  // Suppress cases where the '0' value is expanded from a macro.
+  if (E->getLocStart().isMacroID())
+    return false;
+
+  llvm::APSInt Value;
+  return E->isIntegerConstantExpr(Value, S.Context) && Value == 0;
+}
+
+static bool HasEnumType(Expr *E) {
+  // Strip off implicit integral promotions.
+  while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
+    if (ICE->getCastKind() != CK_IntegralCast &&
+        ICE->getCastKind() != CK_NoOp)
+      break;
+    E = ICE->getSubExpr();
+  }
+
+  return E->getType()->isEnumeralType();
+}
+
+static void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) {
+  BinaryOperatorKind op = E->getOpcode();
+  if (E->isValueDependent())
+    return;
+
+  if (op == BO_LT && IsZero(S, E->getRHS())) {
+    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
+      << "< 0" << "false" << HasEnumType(E->getLHS())
+      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
+  } else if (op == BO_GE && IsZero(S, E->getRHS())) {
+    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
+      << ">= 0" << "true" << HasEnumType(E->getLHS())
+      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
+  } else if (op == BO_GT && IsZero(S, E->getLHS())) {
+    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
+      << "0 >" << "false" << HasEnumType(E->getRHS())
+      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
+  } else if (op == BO_LE && IsZero(S, E->getLHS())) {
+    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
+      << "0 <=" << "true" << HasEnumType(E->getRHS())
+      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
+  }
+}
+
+/// Analyze the operands of the given comparison.  Implements the
+/// fallback case from AnalyzeComparison.
+static void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) {
+  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
+  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
+}
+
+/// \brief Implements -Wsign-compare.
+///
+/// \param E the binary operator to check for warnings
+static void AnalyzeComparison(Sema &S, BinaryOperator *E) {
+  // The type the comparison is being performed in.
+  QualType T = E->getLHS()->getType();
+  assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType())
+         && "comparison with mismatched types");
+
+  // We don't do anything special if this isn't an unsigned integral
+  // comparison:  we're only interested in integral comparisons, and
+  // signed comparisons only happen in cases we don't care to warn about.
+  //
+  // We also don't care about value-dependent expressions or expressions
+  // whose result is a constant.
+  if (!T->hasUnsignedIntegerRepresentation()
+      || E->isValueDependent() || E->isIntegerConstantExpr(S.Context))
+    return AnalyzeImpConvsInComparison(S, E);
+
+  Expr *LHS = E->getLHS()->IgnoreParenImpCasts();
+  Expr *RHS = E->getRHS()->IgnoreParenImpCasts();
+
+  // Check to see if one of the (unmodified) operands is of different
+  // signedness.
+  Expr *signedOperand, *unsignedOperand;
+  if (LHS->getType()->hasSignedIntegerRepresentation()) {
+    assert(!RHS->getType()->hasSignedIntegerRepresentation() &&
+           "unsigned comparison between two signed integer expressions?");
+    signedOperand = LHS;
+    unsignedOperand = RHS;
+  } else if (RHS->getType()->hasSignedIntegerRepresentation()) {
+    signedOperand = RHS;
+    unsignedOperand = LHS;
+  } else {
+    CheckTrivialUnsignedComparison(S, E);
+    return AnalyzeImpConvsInComparison(S, E);
+  }
+
+  // Otherwise, calculate the effective range of the signed operand.
+  IntRange signedRange = GetExprRange(S.Context, signedOperand);
+
+  // Go ahead and analyze implicit conversions in the operands.  Note
+  // that we skip the implicit conversions on both sides.
+  AnalyzeImplicitConversions(S, LHS, E->getOperatorLoc());
+  AnalyzeImplicitConversions(S, RHS, E->getOperatorLoc());
+
+  // If the signed range is non-negative, -Wsign-compare won't fire,
+  // but we should still check for comparisons which are always true
+  // or false.
+  if (signedRange.NonNegative)
+    return CheckTrivialUnsignedComparison(S, E);
+
+  // For (in)equality comparisons, if the unsigned operand is a
+  // constant which cannot collide with a overflowed signed operand,
+  // then reinterpreting the signed operand as unsigned will not
+  // change the result of the comparison.
+  if (E->isEqualityOp()) {
+    unsigned comparisonWidth = S.Context.getIntWidth(T);
+    IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand);
+
+    // We should never be unable to prove that the unsigned operand is
+    // non-negative.
+    assert(unsignedRange.NonNegative && "unsigned range includes negative?");
+
+    if (unsignedRange.Width < comparisonWidth)
+      return;
+  }
+
+  S.Diag(E->getOperatorLoc(), diag::warn_mixed_sign_comparison)
+    << LHS->getType() << RHS->getType()
+    << LHS->getSourceRange() << RHS->getSourceRange();
+}
+
+/// Analyzes an attempt to assign the given value to a bitfield.
+///
+/// Returns true if there was something fishy about the attempt.
+static bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init,
+                                      SourceLocation InitLoc) {
+  assert(Bitfield->isBitField());
+  if (Bitfield->isInvalidDecl())
+    return false;
+
+  // White-list bool bitfields.
+  if (Bitfield->getType()->isBooleanType())
+    return false;
+
+  // Ignore value- or type-dependent expressions.
+  if (Bitfield->getBitWidth()->isValueDependent() ||
+      Bitfield->getBitWidth()->isTypeDependent() ||
+      Init->isValueDependent() ||
+      Init->isTypeDependent())
+    return false;
+
+  Expr *OriginalInit = Init->IgnoreParenImpCasts();
+
+  llvm::APSInt Value;
+  if (!OriginalInit->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects))
+    return false;
+
+  unsigned OriginalWidth = Value.getBitWidth();
+  unsigned FieldWidth = Bitfield->getBitWidthValue(S.Context);
+
+  if (OriginalWidth <= FieldWidth)
+    return false;
+
+  // Compute the value which the bitfield will contain.
+  llvm::APSInt TruncatedValue = Value.trunc(FieldWidth);
+  TruncatedValue.setIsSigned(Bitfield->getType()->isSignedIntegerType());
+
+  // Check whether the stored value is equal to the original value.
+  TruncatedValue = TruncatedValue.extend(OriginalWidth);
+  if (Value == TruncatedValue)
+    return false;
+
+  // Special-case bitfields of width 1: booleans are naturally 0/1, and
+  // therefore don't strictly fit into a signed bitfield of width 1.
+  if (FieldWidth == 1 && Value == 1)
+    return false;
+
+  std::string PrettyValue = Value.toString(10);
+  std::string PrettyTrunc = TruncatedValue.toString(10);
+
+  S.Diag(InitLoc, diag::warn_impcast_bitfield_precision_constant)
+    << PrettyValue << PrettyTrunc << OriginalInit->getType()
+    << Init->getSourceRange();
+
+  return true;
+}
+
+/// Analyze the given simple or compound assignment for warning-worthy
+/// operations.
+static void AnalyzeAssignment(Sema &S, BinaryOperator *E) {
+  // Just recurse on the LHS.
+  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
+
+  // We want to recurse on the RHS as normal unless we're assigning to
+  // a bitfield.
+  if (FieldDecl *Bitfield = E->getLHS()->getBitField()) {
+    if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(),
+                                  E->getOperatorLoc())) {
+      // Recurse, ignoring any implicit conversions on the RHS.
+      return AnalyzeImplicitConversions(S, E->getRHS()->IgnoreParenImpCasts(),
+                                        E->getOperatorLoc());
+    }
+  }
+
+  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
+}
+
+/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
+static void DiagnoseImpCast(Sema &S, Expr *E, QualType SourceType, QualType T, 
+                            SourceLocation CContext, unsigned diag,
+                            bool pruneControlFlow = false) {
+  if (pruneControlFlow) {
+    S.DiagRuntimeBehavior(E->getExprLoc(), E,
+                          S.PDiag(diag)
+                            << SourceType << T << E->getSourceRange()
+                            << SourceRange(CContext));
+    return;
+  }
+  S.Diag(E->getExprLoc(), diag)
+    << SourceType << T << E->getSourceRange() << SourceRange(CContext);
+}
+
+/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
+static void DiagnoseImpCast(Sema &S, Expr *E, QualType T,
+                            SourceLocation CContext, unsigned diag,
+                            bool pruneControlFlow = false) {
+  DiagnoseImpCast(S, E, E->getType(), T, CContext, diag, pruneControlFlow);
+}
+
+/// Diagnose an implicit cast from a literal expression. Does not warn when the
+/// cast wouldn't lose information.
+void DiagnoseFloatingLiteralImpCast(Sema &S, FloatingLiteral *FL, QualType T,
+                                    SourceLocation CContext) {
+  // Try to convert the literal exactly to an integer. If we can, don't warn.
+  bool isExact = false;
+  const llvm::APFloat &Value = FL->getValue();
+  llvm::APSInt IntegerValue(S.Context.getIntWidth(T),
+                            T->hasUnsignedIntegerRepresentation());
+  if (Value.convertToInteger(IntegerValue,
+                             llvm::APFloat::rmTowardZero, &isExact)
+      == llvm::APFloat::opOK && isExact)
+    return;
+
+  S.Diag(FL->getExprLoc(), diag::warn_impcast_literal_float_to_integer)
+    << FL->getType() << T << FL->getSourceRange() << SourceRange(CContext);
+}
+
+std::string PrettyPrintInRange(const llvm::APSInt &Value, IntRange Range) {
+  if (!Range.Width) return "0";
+
+  llvm::APSInt ValueInRange = Value;
+  ValueInRange.setIsSigned(!Range.NonNegative);
+  ValueInRange = ValueInRange.trunc(Range.Width);
+  return ValueInRange.toString(10);
+}
+
+void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
+                             SourceLocation CC, bool *ICContext = 0) {
+  if (E->isTypeDependent() || E->isValueDependent()) return;
+
+  const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr();
+  const Type *Target = S.Context.getCanonicalType(T).getTypePtr();
+  if (Source == Target) return;
+  if (Target->isDependentType()) return;
+
+  // If the conversion context location is invalid don't complain. We also
+  // don't want to emit a warning if the issue occurs from the expansion of
+  // a system macro. The problem is that 'getSpellingLoc()' is slow, so we
+  // delay this check as long as possible. Once we detect we are in that
+  // scenario, we just return.
+  if (CC.isInvalid())
+    return;
+
+  // Diagnose implicit casts to bool.
+  if (Target->isSpecificBuiltinType(BuiltinType::Bool)) {
+    if (isa<StringLiteral>(E))
+      // Warn on string literal to bool.  Checks for string literals in logical
+      // expressions, for instances, assert(0 && "error here"), is prevented
+      // by a check in AnalyzeImplicitConversions().
+      return DiagnoseImpCast(S, E, T, CC,
+                             diag::warn_impcast_string_literal_to_bool);
+    if (Source->isFunctionType()) {
+      // Warn on function to bool. Checks free functions and static member
+      // functions. Weakly imported functions are excluded from the check,
+      // since it's common to test their value to check whether the linker
+      // found a definition for them.
+      ValueDecl *D = 0;
+      if (DeclRefExpr* R = dyn_cast<DeclRefExpr>(E)) {
+        D = R->getDecl();
+      } else if (MemberExpr *M = dyn_cast<MemberExpr>(E)) {
+        D = M->getMemberDecl();
+      }
+
+      if (D && !D->isWeak()) {
+        if (FunctionDecl* F = dyn_cast<FunctionDecl>(D)) {
+          S.Diag(E->getExprLoc(), diag::warn_impcast_function_to_bool)
+            << F << E->getSourceRange() << SourceRange(CC);
+          S.Diag(E->getExprLoc(), diag::note_function_to_bool_silence)
+            << FixItHint::CreateInsertion(E->getExprLoc(), "&");
+          QualType ReturnType;
+          UnresolvedSet<4> NonTemplateOverloads;
+          S.isExprCallable(*E, ReturnType, NonTemplateOverloads);
+          if (!ReturnType.isNull() 
+              && ReturnType->isSpecificBuiltinType(BuiltinType::Bool))
+            S.Diag(E->getExprLoc(), diag::note_function_to_bool_call)
+              << FixItHint::CreateInsertion(
+                 S.getPreprocessor().getLocForEndOfToken(E->getLocEnd()), "()");
+          return;
+        }
+      }
+    }
+    return; // Other casts to bool are not checked.
+  }
+
+  // Strip vector types.
+  if (isa<VectorType>(Source)) {
+    if (!isa<VectorType>(Target)) {
+      if (S.SourceMgr.isInSystemMacro(CC))
+        return;
+      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_vector_scalar);
+    }
+    
+    // If the vector cast is cast between two vectors of the same size, it is
+    // a bitcast, not a conversion.
+    if (S.Context.getTypeSize(Source) == S.Context.getTypeSize(Target))
+      return;
+
+    Source = cast<VectorType>(Source)->getElementType().getTypePtr();
+    Target = cast<VectorType>(Target)->getElementType().getTypePtr();
+  }
+
+  // Strip complex types.
+  if (isa<ComplexType>(Source)) {
+    if (!isa<ComplexType>(Target)) {
+      if (S.SourceMgr.isInSystemMacro(CC))
+        return;
+
+      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_complex_scalar);
+    }
+
+    Source = cast<ComplexType>(Source)->getElementType().getTypePtr();
+    Target = cast<ComplexType>(Target)->getElementType().getTypePtr();
+  }
+
+  const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source);
+  const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target);
+
+  // If the source is floating point...
+  if (SourceBT && SourceBT->isFloatingPoint()) {
+    // ...and the target is floating point...
+    if (TargetBT && TargetBT->isFloatingPoint()) {
+      // ...then warn if we're dropping FP rank.
+
+      // Builtin FP kinds are ordered by increasing FP rank.
+      if (SourceBT->getKind() > TargetBT->getKind()) {
+        // Don't warn about float constants that are precisely
+        // representable in the target type.
+        Expr::EvalResult result;
+        if (E->EvaluateAsRValue(result, S.Context)) {
+          // Value might be a float, a float vector, or a float complex.
+          if (IsSameFloatAfterCast(result.Val,
+                   S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)),
+                   S.Context.getFloatTypeSemantics(QualType(SourceBT, 0))))
+            return;
+        }
+
+        if (S.SourceMgr.isInSystemMacro(CC))
+          return;
+
+        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_precision);
+      }
+      return;
+    }
+
+    // If the target is integral, always warn.    
+    if ((TargetBT && TargetBT->isInteger())) {
+      if (S.SourceMgr.isInSystemMacro(CC))
+        return;
+      
+      Expr *InnerE = E->IgnoreParenImpCasts();
+      // We also want to warn on, e.g., "int i = -1.234"
+      if (UnaryOperator *UOp = dyn_cast<UnaryOperator>(InnerE))
+        if (UOp->getOpcode() == UO_Minus || UOp->getOpcode() == UO_Plus)
+          InnerE = UOp->getSubExpr()->IgnoreParenImpCasts();
+
+      if (FloatingLiteral *FL = dyn_cast<FloatingLiteral>(InnerE)) {
+        DiagnoseFloatingLiteralImpCast(S, FL, T, CC);
+      } else {
+        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_integer);
+      }
+    }
+
+    return;
+  }
+
+  if (!Source->isIntegerType() || !Target->isIntegerType())
+    return;
+
+  if ((E->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull)
+           == Expr::NPCK_GNUNull) && Target->isIntegerType()) {
+    SourceLocation Loc = E->getSourceRange().getBegin();
+    if (Loc.isMacroID())
+      Loc = S.SourceMgr.getImmediateExpansionRange(Loc).first;
+    S.Diag(Loc, diag::warn_impcast_null_pointer_to_integer)
+        << T << Loc << clang::SourceRange(CC);
+    return;
+  }
+
+  IntRange SourceRange = GetExprRange(S.Context, E);
+  IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target);
+
+  if (SourceRange.Width > TargetRange.Width) {
+    // If the source is a constant, use a default-on diagnostic.
+    // TODO: this should happen for bitfield stores, too.
+    llvm::APSInt Value(32);
+    if (E->isIntegerConstantExpr(Value, S.Context)) {
+      if (S.SourceMgr.isInSystemMacro(CC))
+        return;
+
+      std::string PrettySourceValue = Value.toString(10);
+      std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange);
+
+      S.DiagRuntimeBehavior(E->getExprLoc(), E,
+        S.PDiag(diag::warn_impcast_integer_precision_constant)
+            << PrettySourceValue << PrettyTargetValue
+            << E->getType() << T << E->getSourceRange()
+            << clang::SourceRange(CC));
+      return;
+    }
+
+    // People want to build with -Wshorten-64-to-32 and not -Wconversion.
+    if (S.SourceMgr.isInSystemMacro(CC))
+      return;
+    
+    if (TargetRange.Width == 32 && S.Context.getIntWidth(E->getType()) == 64)
+      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_64_32,
+                             /* pruneControlFlow */ true);
+    return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_precision);
+  }
+
+  if ((TargetRange.NonNegative && !SourceRange.NonNegative) ||
+      (!TargetRange.NonNegative && SourceRange.NonNegative &&
+       SourceRange.Width == TargetRange.Width)) {
+        
+    if (S.SourceMgr.isInSystemMacro(CC))
+      return;
+
+    unsigned DiagID = diag::warn_impcast_integer_sign;
+
+    // Traditionally, gcc has warned about this under -Wsign-compare.
+    // We also want to warn about it in -Wconversion.
+    // So if -Wconversion is off, use a completely identical diagnostic
+    // in the sign-compare group.
+    // The conditional-checking code will 
+    if (ICContext) {
+      DiagID = diag::warn_impcast_integer_sign_conditional;
+      *ICContext = true;
+    }
+
+    return DiagnoseImpCast(S, E, T, CC, DiagID);
+  }
+
+  // Diagnose conversions between different enumeration types.
+  // In C, we pretend that the type of an EnumConstantDecl is its enumeration
+  // type, to give us better diagnostics.
+  QualType SourceType = E->getType();
+  if (!S.getLangOpts().CPlusPlus) {
+    if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
+      if (EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(DRE->getDecl())) {
+        EnumDecl *Enum = cast<EnumDecl>(ECD->getDeclContext());
+        SourceType = S.Context.getTypeDeclType(Enum);
+        Source = S.Context.getCanonicalType(SourceType).getTypePtr();
+      }
+  }
+  
+  if (const EnumType *SourceEnum = Source->getAs<EnumType>())
+    if (const EnumType *TargetEnum = Target->getAs<EnumType>())
+      if ((SourceEnum->getDecl()->getIdentifier() || 
+           SourceEnum->getDecl()->getTypedefNameForAnonDecl()) &&
+          (TargetEnum->getDecl()->getIdentifier() ||
+           TargetEnum->getDecl()->getTypedefNameForAnonDecl()) &&
+          SourceEnum != TargetEnum) {
+        if (S.SourceMgr.isInSystemMacro(CC))
+          return;
+
+        return DiagnoseImpCast(S, E, SourceType, T, CC, 
+                               diag::warn_impcast_different_enum_types);
+      }
+  
+  return;
+}
+
+void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T);
+
+void CheckConditionalOperand(Sema &S, Expr *E, QualType T,
+                             SourceLocation CC, bool &ICContext) {
+  E = E->IgnoreParenImpCasts();
+
+  if (isa<ConditionalOperator>(E))
+    return CheckConditionalOperator(S, cast<ConditionalOperator>(E), T);
+
+  AnalyzeImplicitConversions(S, E, CC);
+  if (E->getType() != T)
+    return CheckImplicitConversion(S, E, T, CC, &ICContext);
+  return;
+}
+
+void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T) {
+  SourceLocation CC = E->getQuestionLoc();
+
+  AnalyzeImplicitConversions(S, E->getCond(), CC);
+
+  bool Suspicious = false;
+  CheckConditionalOperand(S, E->getTrueExpr(), T, CC, Suspicious);
+  CheckConditionalOperand(S, E->getFalseExpr(), T, CC, Suspicious);
+
+  // If -Wconversion would have warned about either of the candidates
+  // for a signedness conversion to the context type...
+  if (!Suspicious) return;
+
+  // ...but it's currently ignored...
+  if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional,
+                                 CC))
+    return;
+
+  // ...then check whether it would have warned about either of the
+  // candidates for a signedness conversion to the condition type.
+  if (E->getType() == T) return;
+ 
+  Suspicious = false;
+  CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(),
+                          E->getType(), CC, &Suspicious);
+  if (!Suspicious)
+    CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(),
+                            E->getType(), CC, &Suspicious);
+}
+
+/// AnalyzeImplicitConversions - Find and report any interesting
+/// implicit conversions in the given expression.  There are a couple
+/// of competing diagnostics here, -Wconversion and -Wsign-compare.
+void AnalyzeImplicitConversions(Sema &S, Expr *OrigE, SourceLocation CC) {
+  QualType T = OrigE->getType();
+  Expr *E = OrigE->IgnoreParenImpCasts();
+
+  if (E->isTypeDependent() || E->isValueDependent())
+    return;
+
+  // For conditional operators, we analyze the arguments as if they
+  // were being fed directly into the output.
+  if (isa<ConditionalOperator>(E)) {
+    ConditionalOperator *CO = cast<ConditionalOperator>(E);
+    CheckConditionalOperator(S, CO, T);
+    return;
+  }
+
+  // Go ahead and check any implicit conversions we might have skipped.
+  // The non-canonical typecheck is just an optimization;
+  // CheckImplicitConversion will filter out dead implicit conversions.
+  if (E->getType() != T)
+    CheckImplicitConversion(S, E, T, CC);
+
+  // Now continue drilling into this expression.
+
+  // Skip past explicit casts.
+  if (isa<ExplicitCastExpr>(E)) {
+    E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts();
+    return AnalyzeImplicitConversions(S, E, CC);
+  }
+
+  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
+    // Do a somewhat different check with comparison operators.
+    if (BO->isComparisonOp())
+      return AnalyzeComparison(S, BO);
+
+    // And with simple assignments.
+    if (BO->getOpcode() == BO_Assign)
+      return AnalyzeAssignment(S, BO);
+  }
+
+  // These break the otherwise-useful invariant below.  Fortunately,
+  // we don't really need to recurse into them, because any internal
+  // expressions should have been analyzed already when they were
+  // built into statements.
+  if (isa<StmtExpr>(E)) return;
+
+  // Don't descend into unevaluated contexts.
+  if (isa<UnaryExprOrTypeTraitExpr>(E)) return;
+
+  // Now just recurse over the expression's children.
+  CC = E->getExprLoc();
+  BinaryOperator *BO = dyn_cast<BinaryOperator>(E);
+  bool IsLogicalOperator = BO && BO->isLogicalOp();
+  for (Stmt::child_range I = E->children(); I; ++I) {
+    Expr *ChildExpr = dyn_cast_or_null<Expr>(*I);
+    if (!ChildExpr)
+      continue;
+
+    if (IsLogicalOperator &&
+        isa<StringLiteral>(ChildExpr->IgnoreParenImpCasts()))
+      // Ignore checking string literals that are in logical operators.
+      continue;
+    AnalyzeImplicitConversions(S, ChildExpr, CC);
+  }
+}
+
+} // end anonymous namespace
+
+/// Diagnoses "dangerous" implicit conversions within the given
+/// expression (which is a full expression).  Implements -Wconversion
+/// and -Wsign-compare.
+///
+/// \param CC the "context" location of the implicit conversion, i.e.
+///   the most location of the syntactic entity requiring the implicit
+///   conversion
+void Sema::CheckImplicitConversions(Expr *E, SourceLocation CC) {
+  // Don't diagnose in unevaluated contexts.
+  if (ExprEvalContexts.back().Context == Sema::Unevaluated)
+    return;
+
+  // Don't diagnose for value- or type-dependent expressions.
+  if (E->isTypeDependent() || E->isValueDependent())
+    return;
+
+  // Check for array bounds violations in cases where the check isn't triggered
+  // elsewhere for other Expr types (like BinaryOperators), e.g. when an
+  // ArraySubscriptExpr is on the RHS of a variable initialization.
+  CheckArrayAccess(E);
+
+  // This is not the right CC for (e.g.) a variable initialization.
+  AnalyzeImplicitConversions(*this, E, CC);
+}
+
+void Sema::CheckBitFieldInitialization(SourceLocation InitLoc,
+                                       FieldDecl *BitField,
+                                       Expr *Init) {
+  (void) AnalyzeBitFieldAssignment(*this, BitField, Init, InitLoc);
+}
+
+/// CheckParmsForFunctionDef - Check that the parameters of the given
+/// function are appropriate for the definition of a function. This
+/// takes care of any checks that cannot be performed on the
+/// declaration itself, e.g., that the types of each of the function
+/// parameters are complete.
+bool Sema::CheckParmsForFunctionDef(ParmVarDecl **P, ParmVarDecl **PEnd,
+                                    bool CheckParameterNames) {
+  bool HasInvalidParm = false;
+  for (; P != PEnd; ++P) {
+    ParmVarDecl *Param = *P;
+    
+    // C99 6.7.5.3p4: the parameters in a parameter type list in a
+    // function declarator that is part of a function definition of
+    // that function shall not have incomplete type.
+    //
+    // This is also C++ [dcl.fct]p6.
+    if (!Param->isInvalidDecl() &&
+        RequireCompleteType(Param->getLocation(), Param->getType(),
+                               diag::err_typecheck_decl_incomplete_type)) {
+      Param->setInvalidDecl();
+      HasInvalidParm = true;
+    }
+
+    // C99 6.9.1p5: If the declarator includes a parameter type list, the
+    // declaration of each parameter shall include an identifier.
+    if (CheckParameterNames &&
+        Param->getIdentifier() == 0 &&
+        !Param->isImplicit() &&
+        !getLangOpts().CPlusPlus)
+      Diag(Param->getLocation(), diag::err_parameter_name_omitted);
+
+    // C99 6.7.5.3p12:
+    //   If the function declarator is not part of a definition of that
+    //   function, parameters may have incomplete type and may use the [*]
+    //   notation in their sequences of declarator specifiers to specify
+    //   variable length array types.
+    QualType PType = Param->getOriginalType();
+    if (const ArrayType *AT = Context.getAsArrayType(PType)) {
+      if (AT->getSizeModifier() == ArrayType::Star) {
+        // FIXME: This diagnosic should point the the '[*]' if source-location
+        // information is added for it.
+        Diag(Param->getLocation(), diag::err_array_star_in_function_definition);
+      }
+    }
+  }
+
+  return HasInvalidParm;
+}
+
+/// CheckCastAlign - Implements -Wcast-align, which warns when a
+/// pointer cast increases the alignment requirements.
+void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) {
+  // This is actually a lot of work to potentially be doing on every
+  // cast; don't do it if we're ignoring -Wcast_align (as is the default).
+  if (getDiagnostics().getDiagnosticLevel(diag::warn_cast_align,
+                                          TRange.getBegin())
+        == DiagnosticsEngine::Ignored)
+    return;
+
+  // Ignore dependent types.
+  if (T->isDependentType() || Op->getType()->isDependentType())
+    return;
+
+  // Require that the destination be a pointer type.
+  const PointerType *DestPtr = T->getAs<PointerType>();
+  if (!DestPtr) return;
+
+  // If the destination has alignment 1, we're done.
+  QualType DestPointee = DestPtr->getPointeeType();
+  if (DestPointee->isIncompleteType()) return;
+  CharUnits DestAlign = Context.getTypeAlignInChars(DestPointee);
+  if (DestAlign.isOne()) return;
+
+  // Require that the source be a pointer type.
+  const PointerType *SrcPtr = Op->getType()->getAs<PointerType>();
+  if (!SrcPtr) return;
+  QualType SrcPointee = SrcPtr->getPointeeType();
+
+  // Whitelist casts from cv void*.  We already implicitly
+  // whitelisted casts to cv void*, since they have alignment 1.
+  // Also whitelist casts involving incomplete types, which implicitly
+  // includes 'void'.
+  if (SrcPointee->isIncompleteType()) return;
+
+  CharUnits SrcAlign = Context.getTypeAlignInChars(SrcPointee);
+  if (SrcAlign >= DestAlign) return;
+
+  Diag(TRange.getBegin(), diag::warn_cast_align)
+    << Op->getType() << T
+    << static_cast<unsigned>(SrcAlign.getQuantity())
+    << static_cast<unsigned>(DestAlign.getQuantity())
+    << TRange << Op->getSourceRange();
+}
+
+static const Type* getElementType(const Expr *BaseExpr) {
+  const Type* EltType = BaseExpr->getType().getTypePtr();
+  if (EltType->isAnyPointerType())
+    return EltType->getPointeeType().getTypePtr();
+  else if (EltType->isArrayType())
+    return EltType->getBaseElementTypeUnsafe();
+  return EltType;
+}
+
+/// \brief Check whether this array fits the idiom of a size-one tail padded
+/// array member of a struct.
+///
+/// We avoid emitting out-of-bounds access warnings for such arrays as they are
+/// commonly used to emulate flexible arrays in C89 code.
+static bool IsTailPaddedMemberArray(Sema &S, llvm::APInt Size,
+                                    const NamedDecl *ND) {
+  if (Size != 1 || !ND) return false;
+
+  const FieldDecl *FD = dyn_cast<FieldDecl>(ND);
+  if (!FD) return false;
+
+  // Don't consider sizes resulting from macro expansions or template argument
+  // substitution to form C89 tail-padded arrays.
+  ConstantArrayTypeLoc TL =
+    cast<ConstantArrayTypeLoc>(FD->getTypeSourceInfo()->getTypeLoc());
+  const Expr *SizeExpr = dyn_cast<IntegerLiteral>(TL.getSizeExpr());
+  if (!SizeExpr || SizeExpr->getExprLoc().isMacroID())
+    return false;
+
+  const RecordDecl *RD = dyn_cast<RecordDecl>(FD->getDeclContext());
+  if (!RD) return false;
+  if (RD->isUnion()) return false;
+  if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD)) {
+    if (!CRD->isStandardLayout()) return false;
+  }
+
+  // See if this is the last field decl in the record.
+  const Decl *D = FD;
+  while ((D = D->getNextDeclInContext()))
+    if (isa<FieldDecl>(D))
+      return false;
+  return true;
+}
+
+void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
+                            const ArraySubscriptExpr *ASE,
+                            bool AllowOnePastEnd, bool IndexNegated) {
+  IndexExpr = IndexExpr->IgnoreParenImpCasts();
+  if (IndexExpr->isValueDependent())
+    return;
+
+  const Type *EffectiveType = getElementType(BaseExpr);
+  BaseExpr = BaseExpr->IgnoreParenCasts();
+  const ConstantArrayType *ArrayTy =
+    Context.getAsConstantArrayType(BaseExpr->getType());
+  if (!ArrayTy)
+    return;
+
+  llvm::APSInt index;
+  if (!IndexExpr->EvaluateAsInt(index, Context))
+    return;
+  if (IndexNegated)
+    index = -index;
+
+  const NamedDecl *ND = NULL;
+  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
+    ND = dyn_cast<NamedDecl>(DRE->getDecl());
+  if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
+    ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
+
+  if (index.isUnsigned() || !index.isNegative()) {
+    llvm::APInt size = ArrayTy->getSize();
+    if (!size.isStrictlyPositive())
+      return;
+
+    const Type* BaseType = getElementType(BaseExpr);
+    if (BaseType != EffectiveType) {
+      // Make sure we're comparing apples to apples when comparing index to size
+      uint64_t ptrarith_typesize = Context.getTypeSize(EffectiveType);
+      uint64_t array_typesize = Context.getTypeSize(BaseType);
+      // Handle ptrarith_typesize being zero, such as when casting to void*
+      if (!ptrarith_typesize) ptrarith_typesize = 1;
+      if (ptrarith_typesize != array_typesize) {
+        // There's a cast to a different size type involved
+        uint64_t ratio = array_typesize / ptrarith_typesize;
+        // TODO: Be smarter about handling cases where array_typesize is not a
+        // multiple of ptrarith_typesize
+        if (ptrarith_typesize * ratio == array_typesize)
+          size *= llvm::APInt(size.getBitWidth(), ratio);
+      }
+    }
+
+    if (size.getBitWidth() > index.getBitWidth())
+      index = index.zext(size.getBitWidth());
+    else if (size.getBitWidth() < index.getBitWidth())
+      size = size.zext(index.getBitWidth());
+
+    // For array subscripting the index must be less than size, but for pointer
+    // arithmetic also allow the index (offset) to be equal to size since
+    // computing the next address after the end of the array is legal and
+    // commonly done e.g. in C++ iterators and range-based for loops.
+    if (AllowOnePastEnd ? index.ule(size) : index.ult(size))
+      return;
+
+    // Also don't warn for arrays of size 1 which are members of some
+    // structure. These are often used to approximate flexible arrays in C89
+    // code.
+    if (IsTailPaddedMemberArray(*this, size, ND))
+      return;
+
+    // Suppress the warning if the subscript expression (as identified by the
+    // ']' location) and the index expression are both from macro expansions
+    // within a system header.
+    if (ASE) {
+      SourceLocation RBracketLoc = SourceMgr.getSpellingLoc(
+          ASE->getRBracketLoc());
+      if (SourceMgr.isInSystemHeader(RBracketLoc)) {
+        SourceLocation IndexLoc = SourceMgr.getSpellingLoc(
+            IndexExpr->getLocStart());
+        if (SourceMgr.isFromSameFile(RBracketLoc, IndexLoc))
+          return;
+      }
+    }
+
+    unsigned DiagID = diag::warn_ptr_arith_exceeds_bounds;
+    if (ASE)
+      DiagID = diag::warn_array_index_exceeds_bounds;
+
+    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
+                        PDiag(DiagID) << index.toString(10, true)
+                          << size.toString(10, true)
+                          << (unsigned)size.getLimitedValue(~0U)
+                          << IndexExpr->getSourceRange());
+  } else {
+    unsigned DiagID = diag::warn_array_index_precedes_bounds;
+    if (!ASE) {
+      DiagID = diag::warn_ptr_arith_precedes_bounds;
+      if (index.isNegative()) index = -index;
+    }
+
+    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
+                        PDiag(DiagID) << index.toString(10, true)
+                          << IndexExpr->getSourceRange());
+  }
+
+  if (!ND) {
+    // Try harder to find a NamedDecl to point at in the note.
+    while (const ArraySubscriptExpr *ASE =
+           dyn_cast<ArraySubscriptExpr>(BaseExpr))
+      BaseExpr = ASE->getBase()->IgnoreParenCasts();
+    if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
+      ND = dyn_cast<NamedDecl>(DRE->getDecl());
+    if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
+      ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
+  }
+
+  if (ND)
+    DiagRuntimeBehavior(ND->getLocStart(), BaseExpr,
+                        PDiag(diag::note_array_index_out_of_bounds)
+                          << ND->getDeclName());
+}
+
+void Sema::CheckArrayAccess(const Expr *expr) {
+  int AllowOnePastEnd = 0;
+  while (expr) {
+    expr = expr->IgnoreParenImpCasts();
+    switch (expr->getStmtClass()) {
+      case Stmt::ArraySubscriptExprClass: {
+        const ArraySubscriptExpr *ASE = cast<ArraySubscriptExpr>(expr);
+        CheckArrayAccess(ASE->getBase(), ASE->getIdx(), ASE,
+                         AllowOnePastEnd > 0);
+        return;
+      }
+      case Stmt::UnaryOperatorClass: {
+        // Only unwrap the * and & unary operators
+        const UnaryOperator *UO = cast<UnaryOperator>(expr);
+        expr = UO->getSubExpr();
+        switch (UO->getOpcode()) {
+          case UO_AddrOf:
+            AllowOnePastEnd++;
+            break;
+          case UO_Deref:
+            AllowOnePastEnd--;
+            break;
+          default:
+            return;
+        }
+        break;
+      }
+      case Stmt::ConditionalOperatorClass: {
+        const ConditionalOperator *cond = cast<ConditionalOperator>(expr);
+        if (const Expr *lhs = cond->getLHS())
+          CheckArrayAccess(lhs);
+        if (const Expr *rhs = cond->getRHS())
+          CheckArrayAccess(rhs);
+        return;
+      }
+      default:
+        return;
+    }
+  }
+}
+
+//===--- CHECK: Objective-C retain cycles ----------------------------------//
+
+namespace {
+  struct RetainCycleOwner {
+    RetainCycleOwner() : Variable(0), Indirect(false) {}
+    VarDecl *Variable;
+    SourceRange Range;
+    SourceLocation Loc;
+    bool Indirect;
+
+    void setLocsFrom(Expr *e) {
+      Loc = e->getExprLoc();
+      Range = e->getSourceRange();
+    }
+  };
+}
+
+/// Consider whether capturing the given variable can possibly lead to
+/// a retain cycle.
+static bool considerVariable(VarDecl *var, Expr *ref, RetainCycleOwner &owner) {
+  // In ARC, it's captured strongly iff the variable has __strong
+  // lifetime.  In MRR, it's captured strongly if the variable is
+  // __block and has an appropriate type.
+  if (var->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
+    return false;
+
+  owner.Variable = var;
+  owner.setLocsFrom(ref);
+  return true;
+}
+
+static bool findRetainCycleOwner(Sema &S, Expr *e, RetainCycleOwner &owner) {
+  while (true) {
+    e = e->IgnoreParens();
+    if (CastExpr *cast = dyn_cast<CastExpr>(e)) {
+      switch (cast->getCastKind()) {
+      case CK_BitCast:
+      case CK_LValueBitCast:
+      case CK_LValueToRValue:
+      case CK_ARCReclaimReturnedObject:
+        e = cast->getSubExpr();
+        continue;
+
+      default:
+        return false;
+      }
+    }
+
+    if (ObjCIvarRefExpr *ref = dyn_cast<ObjCIvarRefExpr>(e)) {
+      ObjCIvarDecl *ivar = ref->getDecl();
+      if (ivar->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
+        return false;
+
+      // Try to find a retain cycle in the base.
+      if (!findRetainCycleOwner(S, ref->getBase(), owner))
+        return false;
+
+      if (ref->isFreeIvar()) owner.setLocsFrom(ref);
+      owner.Indirect = true;
+      return true;
+    }
+
+    if (DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) {
+      VarDecl *var = dyn_cast<VarDecl>(ref->getDecl());
+      if (!var) return false;
+      return considerVariable(var, ref, owner);
+    }
+
+    if (MemberExpr *member = dyn_cast<MemberExpr>(e)) {
+      if (member->isArrow()) return false;
+
+      // Don't count this as an indirect ownership.
+      e = member->getBase();
+      continue;
+    }
+
+    if (PseudoObjectExpr *pseudo = dyn_cast<PseudoObjectExpr>(e)) {
+      // Only pay attention to pseudo-objects on property references.
+      ObjCPropertyRefExpr *pre
+        = dyn_cast<ObjCPropertyRefExpr>(pseudo->getSyntacticForm()
+                                              ->IgnoreParens());
+      if (!pre) return false;
+      if (pre->isImplicitProperty()) return false;
+      ObjCPropertyDecl *property = pre->getExplicitProperty();
+      if (!property->isRetaining() &&
+          !(property->getPropertyIvarDecl() &&
+            property->getPropertyIvarDecl()->getType()
+              .getObjCLifetime() == Qualifiers::OCL_Strong))
+          return false;
+
+      owner.Indirect = true;
+      if (pre->isSuperReceiver()) {
+        owner.Variable = S.getCurMethodDecl()->getSelfDecl();
+        if (!owner.Variable)
+          return false;
+        owner.Loc = pre->getLocation();
+        owner.Range = pre->getSourceRange();
+        return true;
+      }
+      e = const_cast<Expr*>(cast<OpaqueValueExpr>(pre->getBase())
+                              ->getSourceExpr());
+      continue;
+    }
+
+    // Array ivars?
+
+    return false;
+  }
+}
+
+namespace {
+  struct FindCaptureVisitor : EvaluatedExprVisitor<FindCaptureVisitor> {
+    FindCaptureVisitor(ASTContext &Context, VarDecl *variable)
+      : EvaluatedExprVisitor<FindCaptureVisitor>(Context),
+        Variable(variable), Capturer(0) {}
+
+    VarDecl *Variable;
+    Expr *Capturer;
+
+    void VisitDeclRefExpr(DeclRefExpr *ref) {
+      if (ref->getDecl() == Variable && !Capturer)
+        Capturer = ref;
+    }
+
+    void VisitObjCIvarRefExpr(ObjCIvarRefExpr *ref) {
+      if (Capturer) return;
+      Visit(ref->getBase());
+      if (Capturer && ref->isFreeIvar())
+        Capturer = ref;
+    }
+
+    void VisitBlockExpr(BlockExpr *block) {
+      // Look inside nested blocks 
+      if (block->getBlockDecl()->capturesVariable(Variable))
+        Visit(block->getBlockDecl()->getBody());
+    }
+  };
+}
+
+/// Check whether the given argument is a block which captures a
+/// variable.
+static Expr *findCapturingExpr(Sema &S, Expr *e, RetainCycleOwner &owner) {
+  assert(owner.Variable && owner.Loc.isValid());
+
+  e = e->IgnoreParenCasts();
+  BlockExpr *block = dyn_cast<BlockExpr>(e);
+  if (!block || !block->getBlockDecl()->capturesVariable(owner.Variable))
+    return 0;
+
+  FindCaptureVisitor visitor(S.Context, owner.Variable);
+  visitor.Visit(block->getBlockDecl()->getBody());
+  return visitor.Capturer;
+}
+
+static void diagnoseRetainCycle(Sema &S, Expr *capturer,
+                                RetainCycleOwner &owner) {
+  assert(capturer);
+  assert(owner.Variable && owner.Loc.isValid());
+
+  S.Diag(capturer->getExprLoc(), diag::warn_arc_retain_cycle)
+    << owner.Variable << capturer->getSourceRange();
+  S.Diag(owner.Loc, diag::note_arc_retain_cycle_owner)
+    << owner.Indirect << owner.Range;
+}
+
+/// Check for a keyword selector that starts with the word 'add' or
+/// 'set'.
+static bool isSetterLikeSelector(Selector sel) {
+  if (sel.isUnarySelector()) return false;
+
+  StringRef str = sel.getNameForSlot(0);
+  while (!str.empty() && str.front() == '_') str = str.substr(1);
+  if (str.startswith("set"))
+    str = str.substr(3);
+  else if (str.startswith("add")) {
+    // Specially whitelist 'addOperationWithBlock:'.
+    if (sel.getNumArgs() == 1 && str.startswith("addOperationWithBlock"))
+      return false;
+    str = str.substr(3);
+  }
+  else
+    return false;
+
+  if (str.empty()) return true;
+  return !islower(str.front());
+}
+
+/// Check a message send to see if it's likely to cause a retain cycle.
+void Sema::checkRetainCycles(ObjCMessageExpr *msg) {
+  // Only check instance methods whose selector looks like a setter.
+  if (!msg->isInstanceMessage() || !isSetterLikeSelector(msg->getSelector()))
+    return;
+
+  // Try to find a variable that the receiver is strongly owned by.
+  RetainCycleOwner owner;
+  if (msg->getReceiverKind() == ObjCMessageExpr::Instance) {
+    if (!findRetainCycleOwner(*this, msg->getInstanceReceiver(), owner))
+      return;
+  } else {
+    assert(msg->getReceiverKind() == ObjCMessageExpr::SuperInstance);
+    owner.Variable = getCurMethodDecl()->getSelfDecl();
+    owner.Loc = msg->getSuperLoc();
+    owner.Range = msg->getSuperLoc();
+  }
+
+  // Check whether the receiver is captured by any of the arguments.
+  for (unsigned i = 0, e = msg->getNumArgs(); i != e; ++i)
+    if (Expr *capturer = findCapturingExpr(*this, msg->getArg(i), owner))
+      return diagnoseRetainCycle(*this, capturer, owner);
+}
+
+/// Check a property assign to see if it's likely to cause a retain cycle.
+void Sema::checkRetainCycles(Expr *receiver, Expr *argument) {
+  RetainCycleOwner owner;
+  if (!findRetainCycleOwner(*this, receiver, owner))
+    return;
+
+  if (Expr *capturer = findCapturingExpr(*this, argument, owner))
+    diagnoseRetainCycle(*this, capturer, owner);
+}
+
+bool Sema::checkUnsafeAssigns(SourceLocation Loc,
+                              QualType LHS, Expr *RHS) {
+  Qualifiers::ObjCLifetime LT = LHS.getObjCLifetime();
+  if (LT != Qualifiers::OCL_Weak && LT != Qualifiers::OCL_ExplicitNone)
+    return false;
+  // strip off any implicit cast added to get to the one arc-specific
+  while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
+    if (cast->getCastKind() == CK_ARCConsumeObject) {
+      Diag(Loc, diag::warn_arc_retained_assign)
+        << (LT == Qualifiers::OCL_ExplicitNone) 
+        << RHS->getSourceRange();
+      return true;
+    }
+    RHS = cast->getSubExpr();
+  }
+  return false;
+}
+
+void Sema::checkUnsafeExprAssigns(SourceLocation Loc,
+                              Expr *LHS, Expr *RHS) {
+  QualType LHSType;
+  // PropertyRef on LHS type need be directly obtained from
+  // its declaration as it has a PsuedoType.
+  ObjCPropertyRefExpr *PRE
+    = dyn_cast<ObjCPropertyRefExpr>(LHS->IgnoreParens());
+  if (PRE && !PRE->isImplicitProperty()) {
+    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
+    if (PD)
+      LHSType = PD->getType();
+  }
+  
+  if (LHSType.isNull())
+    LHSType = LHS->getType();
+  if (checkUnsafeAssigns(Loc, LHSType, RHS))
+    return;
+  Qualifiers::ObjCLifetime LT = LHSType.getObjCLifetime();
+  // FIXME. Check for other life times.
+  if (LT != Qualifiers::OCL_None)
+    return;
+  
+  if (PRE) {
+    if (PRE->isImplicitProperty())
+      return;
+    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
+    if (!PD)
+      return;
+    
+    unsigned Attributes = PD->getPropertyAttributes();
+    if (Attributes & ObjCPropertyDecl::OBJC_PR_assign) {
+      // when 'assign' attribute was not explicitly specified
+      // by user, ignore it and rely on property type itself
+      // for lifetime info.
+      unsigned AsWrittenAttr = PD->getPropertyAttributesAsWritten();
+      if (!(AsWrittenAttr & ObjCPropertyDecl::OBJC_PR_assign) &&
+          LHSType->isObjCRetainableType())
+        return;
+        
+      while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
+        if (cast->getCastKind() == CK_ARCConsumeObject) {
+          Diag(Loc, diag::warn_arc_retained_property_assign)
+          << RHS->getSourceRange();
+          return;
+        }
+        RHS = cast->getSubExpr();
+      }
+    }
+  }
+}
+
+//===--- CHECK: Empty statement body (-Wempty-body) ---------------------===//
+
+namespace {
+bool ShouldDiagnoseEmptyStmtBody(const SourceManager &SourceMgr,
+                                 SourceLocation StmtLoc,
+                                 const NullStmt *Body) {
+  // Do not warn if the body is a macro that expands to nothing, e.g:
+  //
+  // #define CALL(x)
+  // if (condition)
+  //   CALL(0);
+  //
+  if (Body->hasLeadingEmptyMacro())
+    return false;
+
+  // Get line numbers of statement and body.
+  bool StmtLineInvalid;
+  unsigned StmtLine = SourceMgr.getSpellingLineNumber(StmtLoc,
+                                                      &StmtLineInvalid);
+  if (StmtLineInvalid)
+    return false;
+
+  bool BodyLineInvalid;
+  unsigned BodyLine = SourceMgr.getSpellingLineNumber(Body->getSemiLoc(),
+                                                      &BodyLineInvalid);
+  if (BodyLineInvalid)
+    return false;
+
+  // Warn if null statement and body are on the same line.
+  if (StmtLine != BodyLine)
+    return false;
+
+  return true;
+}
+} // Unnamed namespace
+
+void Sema::DiagnoseEmptyStmtBody(SourceLocation StmtLoc,
+                                 const Stmt *Body,
+                                 unsigned DiagID) {
+  // Since this is a syntactic check, don't emit diagnostic for template
+  // instantiations, this just adds noise.
+  if (CurrentInstantiationScope)
+    return;
+
+  // The body should be a null statement.
+  const NullStmt *NBody = dyn_cast<NullStmt>(Body);
+  if (!NBody)
+    return;
+
+  // Do the usual checks.
+  if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
+    return;
+
+  Diag(NBody->getSemiLoc(), DiagID);
+  Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
+}
+
+void Sema::DiagnoseEmptyLoopBody(const Stmt *S,
+                                 const Stmt *PossibleBody) {
+  assert(!CurrentInstantiationScope); // Ensured by caller
+
+  SourceLocation StmtLoc;
+  const Stmt *Body;
+  unsigned DiagID;
+  if (const ForStmt *FS = dyn_cast<ForStmt>(S)) {
+    StmtLoc = FS->getRParenLoc();
+    Body = FS->getBody();
+    DiagID = diag::warn_empty_for_body;
+  } else if (const WhileStmt *WS = dyn_cast<WhileStmt>(S)) {
+    StmtLoc = WS->getCond()->getSourceRange().getEnd();
+    Body = WS->getBody();
+    DiagID = diag::warn_empty_while_body;
+  } else
+    return; // Neither `for' nor `while'.
+
+  // The body should be a null statement.
+  const NullStmt *NBody = dyn_cast<NullStmt>(Body);
+  if (!NBody)
+    return;
+
+  // Skip expensive checks if diagnostic is disabled.
+  if (Diags.getDiagnosticLevel(DiagID, NBody->getSemiLoc()) ==
+          DiagnosticsEngine::Ignored)
+    return;
+
+  // Do the usual checks.
+  if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
+    return;
+
+  // `for(...);' and `while(...);' are popular idioms, so in order to keep
+  // noise level low, emit diagnostics only if for/while is followed by a
+  // CompoundStmt, e.g.:
+  //    for (int i = 0; i < n; i++);
+  //    {
+  //      a(i);
+  //    }
+  // or if for/while is followed by a statement with more indentation
+  // than for/while itself:
+  //    for (int i = 0; i < n; i++);
+  //      a(i);
+  bool ProbableTypo = isa<CompoundStmt>(PossibleBody);
+  if (!ProbableTypo) {
+    bool BodyColInvalid;
+    unsigned BodyCol = SourceMgr.getPresumedColumnNumber(
+                             PossibleBody->getLocStart(),
+                             &BodyColInvalid);
+    if (BodyColInvalid)
+      return;
+
+    bool StmtColInvalid;
+    unsigned StmtCol = SourceMgr.getPresumedColumnNumber(
+                             S->getLocStart(),
+                             &StmtColInvalid);
+    if (StmtColInvalid)
+      return;
+
+    if (BodyCol > StmtCol)
+      ProbableTypo = true;
+  }
+
+  if (ProbableTypo) {
+    Diag(NBody->getSemiLoc(), DiagID);
+    Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
+  }
+}