CGExprCXX.cpp revision 7c2349be2d11143a2e59a167fd43362a3bf4585e 
1//===--- CGExprCXX.cpp - Emit LLVM Code for C++ expressions ---------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This contains code dealing with code generation of C++ expressions
11//
12//===----------------------------------------------------------------------===//
13
14#include "clang/Frontend/CodeGenOptions.h"
15#include "CodeGenFunction.h"
16#include "CGCXXABI.h"
17#include "CGObjCRuntime.h"
18#include "CGDebugInfo.h"
19#include "llvm/Intrinsics.h"
20#include "llvm/Support/CallSite.h"
21
22using namespace clang;
23using namespace CodeGen;
24
25RValue CodeGenFunction::EmitCXXMemberCall(const CXXMethodDecl *MD,
26                                          llvm::Value *Callee,
27                                          ReturnValueSlot ReturnValue,
28                                          llvm::Value *This,
29                                          llvm::Value *VTT,
30                                          CallExpr::const_arg_iterator ArgBeg,
31                                          CallExpr::const_arg_iterator ArgEnd) {
32  assert(MD->isInstance() &&
33         "Trying to emit a member call expr on a static method!");
34
35  const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>();
36
37  CallArgList Args;
38
39  // Push the this ptr.
40  Args.add(RValue::get(This), MD->getThisType(getContext()));
41
42  // If there is a VTT parameter, emit it.
43  if (VTT) {
44    QualType T = getContext().getPointerType(getContext().VoidPtrTy);
45    Args.add(RValue::get(VTT), T);
46  }
47
48  // And the rest of the call args
49  EmitCallArgs(Args, FPT, ArgBeg, ArgEnd);
50
51  QualType ResultType = FPT->getResultType();
52  return EmitCall(CGM.getTypes().getFunctionInfo(ResultType, Args,
53                                                 FPT->getExtInfo()),
54                  Callee, ReturnValue, Args, MD);
55}
56
57static const CXXRecordDecl *getMostDerivedClassDecl(const Expr *Base) {
58  const Expr *E = Base;
59
60  while (true) {
61    E = E->IgnoreParens();
62    if (const CastExpr *CE = dyn_cast<CastExpr>(E)) {
63      if (CE->getCastKind() == CK_DerivedToBase ||
64          CE->getCastKind() == CK_UncheckedDerivedToBase ||
65          CE->getCastKind() == CK_NoOp) {
66        E = CE->getSubExpr();
67        continue;
68      }
69    }
70
71    break;
72  }
73
74  QualType DerivedType = E->getType();
75  if (const PointerType *PTy = DerivedType->getAs<PointerType>())
76    DerivedType = PTy->getPointeeType();
77
78  return cast<CXXRecordDecl>(DerivedType->castAs<RecordType>()->getDecl());
79}
80
81// FIXME: Ideally Expr::IgnoreParenNoopCasts should do this, but it doesn't do
82// quite what we want.
83static const Expr *skipNoOpCastsAndParens(const Expr *E) {
84  while (true) {
85    if (const ParenExpr *PE = dyn_cast<ParenExpr>(E)) {
86      E = PE->getSubExpr();
87      continue;
88    }
89
90    if (const CastExpr *CE = dyn_cast<CastExpr>(E)) {
91      if (CE->getCastKind() == CK_NoOp) {
92        E = CE->getSubExpr();
93        continue;
94      }
95    }
96    if (const UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
97      if (UO->getOpcode() == UO_Extension) {
98        E = UO->getSubExpr();
99        continue;
100      }
101    }
102    return E;
103  }
104}
105
106/// canDevirtualizeMemberFunctionCalls - Checks whether virtual calls on given
107/// expr can be devirtualized.
108static bool canDevirtualizeMemberFunctionCalls(ASTContext &Context,
109                                               const Expr *Base,
110                                               const CXXMethodDecl *MD) {
111
112  // When building with -fapple-kext, all calls must go through the vtable since
113  // the kernel linker can do runtime patching of vtables.
114  if (Context.getLangOptions().AppleKext)
115    return false;
116
117  // If the most derived class is marked final, we know that no subclass can
118  // override this member function and so we can devirtualize it. For example:
119  //
120  // struct A { virtual void f(); }
121  // struct B final : A { };
122  //
123  // void f(B *b) {
124  //   b->f();
125  // }
126  //
127  const CXXRecordDecl *MostDerivedClassDecl = getMostDerivedClassDecl(Base);
128  if (MostDerivedClassDecl->hasAttr<FinalAttr>())
129    return true;
130
131  // If the member function is marked 'final', we know that it can't be
132  // overridden and can therefore devirtualize it.
133  if (MD->hasAttr<FinalAttr>())
134    return true;
135
136  // Similarly, if the class itself is marked 'final' it can't be overridden
137  // and we can therefore devirtualize the member function call.
138  if (MD->getParent()->hasAttr<FinalAttr>())
139    return true;
140
141  Base = skipNoOpCastsAndParens(Base);
142  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Base)) {
143    if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl())) {
144      // This is a record decl. We know the type and can devirtualize it.
145      return VD->getType()->isRecordType();
146    }
147
148    return false;
149  }
150
151  // We can always devirtualize calls on temporary object expressions.
152  if (isa<CXXConstructExpr>(Base))
153    return true;
154
155  // And calls on bound temporaries.
156  if (isa<CXXBindTemporaryExpr>(Base))
157    return true;
158
159  // Check if this is a call expr that returns a record type.
160  if (const CallExpr *CE = dyn_cast<CallExpr>(Base))
161    return CE->getCallReturnType()->isRecordType();
162
163  // We can't devirtualize the call.
164  return false;
165}
166
167// Note: This function also emit constructor calls to support a MSVC
168// extensions allowing explicit constructor function call.
169RValue CodeGenFunction::EmitCXXMemberCallExpr(const CXXMemberCallExpr *CE,
170                                              ReturnValueSlot ReturnValue) {
171  const Expr *callee = CE->getCallee()->IgnoreParens();
172
173  if (isa<BinaryOperator>(callee))
174    return EmitCXXMemberPointerCallExpr(CE, ReturnValue);
175
176  const MemberExpr *ME = cast<MemberExpr>(callee);
177  const CXXMethodDecl *MD = cast<CXXMethodDecl>(ME->getMemberDecl());
178
179  CGDebugInfo *DI = getDebugInfo();
180  if (DI && CGM.getCodeGenOpts().LimitDebugInfo
181      && !isa<CallExpr>(ME->getBase())) {
182    QualType PQTy = ME->getBase()->IgnoreParenImpCasts()->getType();
183    if (const PointerType * PTy = dyn_cast<PointerType>(PQTy)) {
184      DI->getOrCreateRecordType(PTy->getPointeeType(),
185                                MD->getParent()->getLocation());
186    }
187  }
188
189  if (MD->isStatic()) {
190    // The method is static, emit it as we would a regular call.
191    llvm::Value *Callee = CGM.GetAddrOfFunction(MD);
192    return EmitCall(getContext().getPointerType(MD->getType()), Callee,
193                    ReturnValue, CE->arg_begin(), CE->arg_end());
194  }
195
196  // Compute the object pointer.
197  llvm::Value *This;
198  if (ME->isArrow())
199    This = EmitScalarExpr(ME->getBase());
200  else
201    This = EmitLValue(ME->getBase()).getAddress();
202
203  if (MD->isTrivial()) {
204    if (isa<CXXDestructorDecl>(MD)) return RValue::get(0);
205    if (isa<CXXConstructorDecl>(MD) &&
206        cast<CXXConstructorDecl>(MD)->isDefaultConstructor())
207      return RValue::get(0);
208
209    if (MD->isCopyAssignmentOperator()) {
210      // We don't like to generate the trivial copy assignment operator when
211      // it isn't necessary; just produce the proper effect here.
212      llvm::Value *RHS = EmitLValue(*CE->arg_begin()).getAddress();
213      EmitAggregateCopy(This, RHS, CE->getType());
214      return RValue::get(This);
215    }
216
217    if (isa<CXXConstructorDecl>(MD) &&
218        cast<CXXConstructorDecl>(MD)->isCopyConstructor()) {
219      llvm::Value *RHS = EmitLValue(*CE->arg_begin()).getAddress();
220      EmitSynthesizedCXXCopyCtorCall(cast<CXXConstructorDecl>(MD), This, RHS,
221                                     CE->arg_begin(), CE->arg_end());
222      return RValue::get(This);
223    }
224    llvm_unreachable("unknown trivial member function");
225  }
226
227  // Compute the function type we're calling.
228  const CGFunctionInfo *FInfo = 0;
229  if (isa<CXXDestructorDecl>(MD))
230    FInfo = &CGM.getTypes().getFunctionInfo(cast<CXXDestructorDecl>(MD),
231                                           Dtor_Complete);
232  else if (isa<CXXConstructorDecl>(MD))
233    FInfo = &CGM.getTypes().getFunctionInfo(cast<CXXConstructorDecl>(MD),
234                                            Ctor_Complete);
235  else
236    FInfo = &CGM.getTypes().getFunctionInfo(MD);
237
238  const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>();
239  llvm::Type *Ty
240    = CGM.getTypes().GetFunctionType(*FInfo, FPT->isVariadic());
241
242  // C++ [class.virtual]p12:
243  //   Explicit qualification with the scope operator (5.1) suppresses the
244  //   virtual call mechanism.
245  //
246  // We also don't emit a virtual call if the base expression has a record type
247  // because then we know what the type is.
248  bool UseVirtualCall;
249  UseVirtualCall = MD->isVirtual() && !ME->hasQualifier()
250                   && !canDevirtualizeMemberFunctionCalls(getContext(),
251                                                          ME->getBase(), MD);
252  llvm::Value *Callee;
253  if (const CXXDestructorDecl *Dtor = dyn_cast<CXXDestructorDecl>(MD)) {
254    if (UseVirtualCall) {
255      Callee = BuildVirtualCall(Dtor, Dtor_Complete, This, Ty);
256    } else {
257      if (getContext().getLangOptions().AppleKext &&
258          MD->isVirtual() &&
259          ME->hasQualifier())
260        Callee = BuildAppleKextVirtualCall(MD, ME->getQualifier(), Ty);
261      else
262        Callee = CGM.GetAddrOfFunction(GlobalDecl(Dtor, Dtor_Complete), Ty);
263    }
264  } else if (const CXXConstructorDecl *Ctor =
265               dyn_cast<CXXConstructorDecl>(MD)) {
266    Callee = CGM.GetAddrOfFunction(GlobalDecl(Ctor, Ctor_Complete), Ty);
267  } else if (UseVirtualCall) {
268      Callee = BuildVirtualCall(MD, This, Ty);
269  } else {
270    if (getContext().getLangOptions().AppleKext &&
271        MD->isVirtual() &&
272        ME->hasQualifier())
273      Callee = BuildAppleKextVirtualCall(MD, ME->getQualifier(), Ty);
274    else
275      Callee = CGM.GetAddrOfFunction(MD, Ty);
276  }
277
278  return EmitCXXMemberCall(MD, Callee, ReturnValue, This, /*VTT=*/0,
279                           CE->arg_begin(), CE->arg_end());
280}
281
282RValue
283CodeGenFunction::EmitCXXMemberPointerCallExpr(const CXXMemberCallExpr *E,
284                                              ReturnValueSlot ReturnValue) {
285  const BinaryOperator *BO =
286      cast<BinaryOperator>(E->getCallee()->IgnoreParens());
287  const Expr *BaseExpr = BO->getLHS();
288  const Expr *MemFnExpr = BO->getRHS();
289
290  const MemberPointerType *MPT =
291    MemFnExpr->getType()->castAs<MemberPointerType>();
292
293  const FunctionProtoType *FPT =
294    MPT->getPointeeType()->castAs<FunctionProtoType>();
295  const CXXRecordDecl *RD =
296    cast<CXXRecordDecl>(MPT->getClass()->getAs<RecordType>()->getDecl());
297
298  // Get the member function pointer.
299  llvm::Value *MemFnPtr = EmitScalarExpr(MemFnExpr);
300
301  // Emit the 'this' pointer.
302  llvm::Value *This;
303
304  if (BO->getOpcode() == BO_PtrMemI)
305    This = EmitScalarExpr(BaseExpr);
306  else
307    This = EmitLValue(BaseExpr).getAddress();
308
309  // Ask the ABI to load the callee.  Note that This is modified.
310  llvm::Value *Callee =
311    CGM.getCXXABI().EmitLoadOfMemberFunctionPointer(*this, This, MemFnPtr, MPT);
312
313  CallArgList Args;
314
315  QualType ThisType =
316    getContext().getPointerType(getContext().getTagDeclType(RD));
317
318  // Push the this ptr.
319  Args.add(RValue::get(This), ThisType);
320
321  // And the rest of the call args
322  EmitCallArgs(Args, FPT, E->arg_begin(), E->arg_end());
323  return EmitCall(CGM.getTypes().getFunctionInfo(Args, FPT), Callee,
324                  ReturnValue, Args);
325}
326
327RValue
328CodeGenFunction::EmitCXXOperatorMemberCallExpr(const CXXOperatorCallExpr *E,
329                                               const CXXMethodDecl *MD,
330                                               ReturnValueSlot ReturnValue) {
331  assert(MD->isInstance() &&
332         "Trying to emit a member call expr on a static method!");
333  LValue LV = EmitLValue(E->getArg(0));
334  llvm::Value *This = LV.getAddress();
335
336  if (MD->isCopyAssignmentOperator()) {
337    const CXXRecordDecl *ClassDecl = cast<CXXRecordDecl>(MD->getDeclContext());
338    if (ClassDecl->hasTrivialCopyAssignment()) {
339      assert(!ClassDecl->hasUserDeclaredCopyAssignment() &&
340             "EmitCXXOperatorMemberCallExpr - user declared copy assignment");
341      llvm::Value *Src = EmitLValue(E->getArg(1)).getAddress();
342      QualType Ty = E->getType();
343      EmitAggregateCopy(This, Src, Ty);
344      return RValue::get(This);
345    }
346  }
347
348  llvm::Value *Callee = EmitCXXOperatorMemberCallee(E, MD, This);
349  return EmitCXXMemberCall(MD, Callee, ReturnValue, This, /*VTT=*/0,
350                           E->arg_begin() + 1, E->arg_end());
351}
352
353void
354CodeGenFunction::EmitCXXConstructExpr(const CXXConstructExpr *E,
355                                      AggValueSlot Dest) {
356  assert(!Dest.isIgnored() && "Must have a destination!");
357  const CXXConstructorDecl *CD = E->getConstructor();
358
359  // If we require zero initialization before (or instead of) calling the
360  // constructor, as can be the case with a non-user-provided default
361  // constructor, emit the zero initialization now, unless destination is
362  // already zeroed.
363  if (E->requiresZeroInitialization() && !Dest.isZeroed())
364    EmitNullInitialization(Dest.getAddr(), E->getType());
365
366  // If this is a call to a trivial default constructor, do nothing.
367  if (CD->isTrivial() && CD->isDefaultConstructor())
368    return;
369
370  // Elide the constructor if we're constructing from a temporary.
371  // The temporary check is required because Sema sets this on NRVO
372  // returns.
373  if (getContext().getLangOptions().ElideConstructors && E->isElidable()) {
374    assert(getContext().hasSameUnqualifiedType(E->getType(),
375                                               E->getArg(0)->getType()));
376    if (E->getArg(0)->isTemporaryObject(getContext(), CD->getParent())) {
377      EmitAggExpr(E->getArg(0), Dest);
378      return;
379    }
380  }
381
382  if (const ConstantArrayType *arrayType
383        = getContext().getAsConstantArrayType(E->getType())) {
384    EmitCXXAggrConstructorCall(CD, arrayType, Dest.getAddr(),
385                               E->arg_begin(), E->arg_end());
386  } else {
387    CXXCtorType Type = Ctor_Complete;
388    bool ForVirtualBase = false;
389
390    switch (E->getConstructionKind()) {
391     case CXXConstructExpr::CK_Delegating:
392      // We should be emitting a constructor; GlobalDecl will assert this
393      Type = CurGD.getCtorType();
394      break;
395
396     case CXXConstructExpr::CK_Complete:
397      Type = Ctor_Complete;
398      break;
399
400     case CXXConstructExpr::CK_VirtualBase:
401      ForVirtualBase = true;
402      // fall-through
403
404     case CXXConstructExpr::CK_NonVirtualBase:
405      Type = Ctor_Base;
406    }
407
408    // Call the constructor.
409    EmitCXXConstructorCall(CD, Type, ForVirtualBase, Dest.getAddr(),
410                           E->arg_begin(), E->arg_end());
411  }
412}
413
414void
415CodeGenFunction::EmitSynthesizedCXXCopyCtor(llvm::Value *Dest,
416                                            llvm::Value *Src,
417                                            const Expr *Exp) {
418  if (const ExprWithCleanups *E = dyn_cast<ExprWithCleanups>(Exp))
419    Exp = E->getSubExpr();
420  assert(isa<CXXConstructExpr>(Exp) &&
421         "EmitSynthesizedCXXCopyCtor - unknown copy ctor expr");
422  const CXXConstructExpr* E = cast<CXXConstructExpr>(Exp);
423  const CXXConstructorDecl *CD = E->getConstructor();
424  RunCleanupsScope Scope(*this);
425
426  // If we require zero initialization before (or instead of) calling the
427  // constructor, as can be the case with a non-user-provided default
428  // constructor, emit the zero initialization now.
429  // FIXME. Do I still need this for a copy ctor synthesis?
430  if (E->requiresZeroInitialization())
431    EmitNullInitialization(Dest, E->getType());
432
433  assert(!getContext().getAsConstantArrayType(E->getType())
434         && "EmitSynthesizedCXXCopyCtor - Copied-in Array");
435  EmitSynthesizedCXXCopyCtorCall(CD, Dest, Src,
436                                 E->arg_begin(), E->arg_end());
437}
438
439static CharUnits CalculateCookiePadding(CodeGenFunction &CGF,
440                                        const CXXNewExpr *E) {
441  if (!E->isArray())
442    return CharUnits::Zero();
443
444  // No cookie is required if the operator new[] being used is the
445  // reserved placement operator new[].
446  if (E->getOperatorNew()->isReservedGlobalPlacementOperator())
447    return CharUnits::Zero();
448
449  return CGF.CGM.getCXXABI().GetArrayCookieSize(E);
450}
451
452static llvm::Value *EmitCXXNewAllocSize(CodeGenFunction &CGF,
453                                        const CXXNewExpr *e,
454                                        llvm::Value *&numElements,
455                                        llvm::Value *&sizeWithoutCookie) {
456  QualType type = e->getAllocatedType();
457
458  if (!e->isArray()) {
459    CharUnits typeSize = CGF.getContext().getTypeSizeInChars(type);
460    sizeWithoutCookie
461      = llvm::ConstantInt::get(CGF.SizeTy, typeSize.getQuantity());
462    return sizeWithoutCookie;
463  }
464
465  // The width of size_t.
466  unsigned sizeWidth = CGF.SizeTy->getBitWidth();
467
468  // Figure out the cookie size.
469  llvm::APInt cookieSize(sizeWidth,
470                         CalculateCookiePadding(CGF, e).getQuantity());
471
472  // Emit the array size expression.
473  // We multiply the size of all dimensions for NumElements.
474  // e.g for 'int[2][3]', ElemType is 'int' and NumElements is 6.
475  numElements = CGF.EmitScalarExpr(e->getArraySize());
476  assert(isa<llvm::IntegerType>(numElements->getType()));
477
478  // The number of elements can be have an arbitrary integer type;
479  // essentially, we need to multiply it by a constant factor, add a
480  // cookie size, and verify that the result is representable as a
481  // size_t.  That's just a gloss, though, and it's wrong in one
482  // important way: if the count is negative, it's an error even if
483  // the cookie size would bring the total size >= 0.
484  bool isSigned
485    = e->getArraySize()->getType()->isSignedIntegerOrEnumerationType();
486  llvm::IntegerType *numElementsType
487    = cast<llvm::IntegerType>(numElements->getType());
488  unsigned numElementsWidth = numElementsType->getBitWidth();
489
490  // Compute the constant factor.
491  llvm::APInt arraySizeMultiplier(sizeWidth, 1);
492  while (const ConstantArrayType *CAT
493             = CGF.getContext().getAsConstantArrayType(type)) {
494    type = CAT->getElementType();
495    arraySizeMultiplier *= CAT->getSize();
496  }
497
498  CharUnits typeSize = CGF.getContext().getTypeSizeInChars(type);
499  llvm::APInt typeSizeMultiplier(sizeWidth, typeSize.getQuantity());
500  typeSizeMultiplier *= arraySizeMultiplier;
501
502  // This will be a size_t.
503  llvm::Value *size;
504
505  // If someone is doing 'new int[42]' there is no need to do a dynamic check.
506  // Don't bloat the -O0 code.
507  if (llvm::ConstantInt *numElementsC =
508        dyn_cast<llvm::ConstantInt>(numElements)) {
509    const llvm::APInt &count = numElementsC->getValue();
510
511    bool hasAnyOverflow = false;
512
513    // If 'count' was a negative number, it's an overflow.
514    if (isSigned && count.isNegative())
515      hasAnyOverflow = true;
516
517    // We want to do all this arithmetic in size_t.  If numElements is
518    // wider than that, check whether it's already too big, and if so,
519    // overflow.
520    else if (numElementsWidth > sizeWidth &&
521             numElementsWidth - sizeWidth > count.countLeadingZeros())
522      hasAnyOverflow = true;
523
524    // Okay, compute a count at the right width.
525    llvm::APInt adjustedCount = count.zextOrTrunc(sizeWidth);
526
527    // Scale numElements by that.  This might overflow, but we don't
528    // care because it only overflows if allocationSize does, too, and
529    // if that overflows then we shouldn't use this.
530    numElements = llvm::ConstantInt::get(CGF.SizeTy,
531                                         adjustedCount * arraySizeMultiplier);
532
533    // Compute the size before cookie, and track whether it overflowed.
534    bool overflow;
535    llvm::APInt allocationSize
536      = adjustedCount.umul_ov(typeSizeMultiplier, overflow);
537    hasAnyOverflow |= overflow;
538
539    // Add in the cookie, and check whether it's overflowed.
540    if (cookieSize != 0) {
541      // Save the current size without a cookie.  This shouldn't be
542      // used if there was overflow.
543      sizeWithoutCookie = llvm::ConstantInt::get(CGF.SizeTy, allocationSize);
544
545      allocationSize = allocationSize.uadd_ov(cookieSize, overflow);
546      hasAnyOverflow |= overflow;
547    }
548
549    // On overflow, produce a -1 so operator new will fail.
550    if (hasAnyOverflow) {
551      size = llvm::Constant::getAllOnesValue(CGF.SizeTy);
552    } else {
553      size = llvm::ConstantInt::get(CGF.SizeTy, allocationSize);
554    }
555
556  // Otherwise, we might need to use the overflow intrinsics.
557  } else {
558    // There are up to four conditions we need to test for:
559    // 1) if isSigned, we need to check whether numElements is negative;
560    // 2) if numElementsWidth > sizeWidth, we need to check whether
561    //   numElements is larger than something representable in size_t;
562    // 3) we need to compute
563    //      sizeWithoutCookie := numElements * typeSizeMultiplier
564    //    and check whether it overflows; and
565    // 4) if we need a cookie, we need to compute
566    //      size := sizeWithoutCookie + cookieSize
567    //    and check whether it overflows.
568
569    llvm::Value *hasOverflow = 0;
570
571    // If numElementsWidth > sizeWidth, then one way or another, we're
572    // going to have to do a comparison for (2), and this happens to
573    // take care of (1), too.
574    if (numElementsWidth > sizeWidth) {
575      llvm::APInt threshold(numElementsWidth, 1);
576      threshold <<= sizeWidth;
577
578      llvm::Value *thresholdV
579        = llvm::ConstantInt::get(numElementsType, threshold);
580
581      hasOverflow = CGF.Builder.CreateICmpUGE(numElements, thresholdV);
582      numElements = CGF.Builder.CreateTrunc(numElements, CGF.SizeTy);
583
584    // Otherwise, if we're signed, we want to sext up to size_t.
585    } else if (isSigned) {
586      if (numElementsWidth < sizeWidth)
587        numElements = CGF.Builder.CreateSExt(numElements, CGF.SizeTy);
588
589      // If there's a non-1 type size multiplier, then we can do the
590      // signedness check at the same time as we do the multiply
591      // because a negative number times anything will cause an
592      // unsigned overflow.  Otherwise, we have to do it here.
593      if (typeSizeMultiplier == 1)
594        hasOverflow = CGF.Builder.CreateICmpSLT(numElements,
595                                      llvm::ConstantInt::get(CGF.SizeTy, 0));
596
597    // Otherwise, zext up to size_t if necessary.
598    } else if (numElementsWidth < sizeWidth) {
599      numElements = CGF.Builder.CreateZExt(numElements, CGF.SizeTy);
600    }
601
602    assert(numElements->getType() == CGF.SizeTy);
603
604    size = numElements;
605
606    // Multiply by the type size if necessary.  This multiplier
607    // includes all the factors for nested arrays.
608    //
609    // This step also causes numElements to be scaled up by the
610    // nested-array factor if necessary.  Overflow on this computation
611    // can be ignored because the result shouldn't be used if
612    // allocation fails.
613    if (typeSizeMultiplier != 1) {
614      llvm::Value *umul_with_overflow
615        = CGF.CGM.getIntrinsic(llvm::Intrinsic::umul_with_overflow, CGF.SizeTy);
616
617      llvm::Value *tsmV =
618        llvm::ConstantInt::get(CGF.SizeTy, typeSizeMultiplier);
619      llvm::Value *result =
620        CGF.Builder.CreateCall2(umul_with_overflow, size, tsmV);
621
622      llvm::Value *overflowed = CGF.Builder.CreateExtractValue(result, 1);
623      if (hasOverflow)
624        hasOverflow = CGF.Builder.CreateOr(hasOverflow, overflowed);
625      else
626        hasOverflow = overflowed;
627
628      size = CGF.Builder.CreateExtractValue(result, 0);
629
630      // Also scale up numElements by the array size multiplier.
631      if (arraySizeMultiplier != 1) {
632        // If the base element type size is 1, then we can re-use the
633        // multiply we just did.
634        if (typeSize.isOne()) {
635          assert(arraySizeMultiplier == typeSizeMultiplier);
636          numElements = size;
637
638        // Otherwise we need a separate multiply.
639        } else {
640          llvm::Value *asmV =
641            llvm::ConstantInt::get(CGF.SizeTy, arraySizeMultiplier);
642          numElements = CGF.Builder.CreateMul(numElements, asmV);
643        }
644      }
645    } else {
646      // numElements doesn't need to be scaled.
647      assert(arraySizeMultiplier == 1);
648    }
649
650    // Add in the cookie size if necessary.
651    if (cookieSize != 0) {
652      sizeWithoutCookie = size;
653
654      llvm::Value *uadd_with_overflow
655        = CGF.CGM.getIntrinsic(llvm::Intrinsic::uadd_with_overflow, CGF.SizeTy);
656
657      llvm::Value *cookieSizeV = llvm::ConstantInt::get(CGF.SizeTy, cookieSize);
658      llvm::Value *result =
659        CGF.Builder.CreateCall2(uadd_with_overflow, size, cookieSizeV);
660
661      llvm::Value *overflowed = CGF.Builder.CreateExtractValue(result, 1);
662      if (hasOverflow)
663        hasOverflow = CGF.Builder.CreateOr(hasOverflow, overflowed);
664      else
665        hasOverflow = overflowed;
666
667      size = CGF.Builder.CreateExtractValue(result, 0);
668    }
669
670    // If we had any possibility of dynamic overflow, make a select to
671    // overwrite 'size' with an all-ones value, which should cause
672    // operator new to throw.
673    if (hasOverflow)
674      size = CGF.Builder.CreateSelect(hasOverflow,
675                                 llvm::Constant::getAllOnesValue(CGF.SizeTy),
676                                      size);
677  }
678
679  if (cookieSize == 0)
680    sizeWithoutCookie = size;
681  else
682    assert(sizeWithoutCookie && "didn't set sizeWithoutCookie?");
683
684  return size;
685}
686
687static void StoreAnyExprIntoOneUnit(CodeGenFunction &CGF, const CXXNewExpr *E,
688                                    llvm::Value *NewPtr) {
689
690  assert(E->getNumConstructorArgs() == 1 &&
691         "Can only have one argument to initializer of POD type.");
692
693  const Expr *Init = E->getConstructorArg(0);
694  QualType AllocType = E->getAllocatedType();
695
696  unsigned Alignment =
697    CGF.getContext().getTypeAlignInChars(AllocType).getQuantity();
698  if (!CGF.hasAggregateLLVMType(AllocType))
699    CGF.EmitScalarInit(Init, 0, CGF.MakeAddrLValue(NewPtr, AllocType, Alignment),
700                       false);
701  else if (AllocType->isAnyComplexType())
702    CGF.EmitComplexExprIntoAddr(Init, NewPtr,
703                                AllocType.isVolatileQualified());
704  else {
705    AggValueSlot Slot
706      = AggValueSlot::forAddr(NewPtr, AllocType.getQualifiers(),
707                              AggValueSlot::IsDestructed,
708                              AggValueSlot::DoesNotNeedGCBarriers);
709    CGF.EmitAggExpr(Init, Slot);
710  }
711}
712
713void
714CodeGenFunction::EmitNewArrayInitializer(const CXXNewExpr *E,
715                                         llvm::Value *NewPtr,
716                                         llvm::Value *NumElements) {
717  // We have a POD type.
718  if (E->getNumConstructorArgs() == 0)
719    return;
720
721  llvm::Type *SizeTy = ConvertType(getContext().getSizeType());
722
723  // Create a temporary for the loop index and initialize it with 0.
724  llvm::Value *IndexPtr = CreateTempAlloca(SizeTy, "loop.index");
725  llvm::Value *Zero = llvm::Constant::getNullValue(SizeTy);
726  Builder.CreateStore(Zero, IndexPtr);
727
728  // Start the loop with a block that tests the condition.
729  llvm::BasicBlock *CondBlock = createBasicBlock("for.cond");
730  llvm::BasicBlock *AfterFor = createBasicBlock("for.end");
731
732  EmitBlock(CondBlock);
733
734  llvm::BasicBlock *ForBody = createBasicBlock("for.body");
735
736  // Generate: if (loop-index < number-of-elements fall to the loop body,
737  // otherwise, go to the block after the for-loop.
738  llvm::Value *Counter = Builder.CreateLoad(IndexPtr);
739  llvm::Value *IsLess = Builder.CreateICmpULT(Counter, NumElements, "isless");
740  // If the condition is true, execute the body.
741  Builder.CreateCondBr(IsLess, ForBody, AfterFor);
742
743  EmitBlock(ForBody);
744
745  llvm::BasicBlock *ContinueBlock = createBasicBlock("for.inc");
746  // Inside the loop body, emit the constructor call on the array element.
747  Counter = Builder.CreateLoad(IndexPtr);
748  llvm::Value *Address = Builder.CreateInBoundsGEP(NewPtr, Counter,
749                                                   "arrayidx");
750  StoreAnyExprIntoOneUnit(*this, E, Address);
751
752  EmitBlock(ContinueBlock);
753
754  // Emit the increment of the loop counter.
755  llvm::Value *NextVal = llvm::ConstantInt::get(SizeTy, 1);
756  Counter = Builder.CreateLoad(IndexPtr);
757  NextVal = Builder.CreateAdd(Counter, NextVal, "inc");
758  Builder.CreateStore(NextVal, IndexPtr);
759
760  // Finally, branch back up to the condition for the next iteration.
761  EmitBranch(CondBlock);
762
763  // Emit the fall-through block.
764  EmitBlock(AfterFor, true);
765}
766
767static void EmitZeroMemSet(CodeGenFunction &CGF, QualType T,
768                           llvm::Value *NewPtr, llvm::Value *Size) {
769  CGF.EmitCastToVoidPtr(NewPtr);
770  CharUnits Alignment = CGF.getContext().getTypeAlignInChars(T);
771  CGF.Builder.CreateMemSet(NewPtr, CGF.Builder.getInt8(0), Size,
772                           Alignment.getQuantity(), false);
773}
774
775static void EmitNewInitializer(CodeGenFunction &CGF, const CXXNewExpr *E,
776                               llvm::Value *NewPtr,
777                               llvm::Value *NumElements,
778                               llvm::Value *AllocSizeWithoutCookie) {
779  if (E->isArray()) {
780    if (CXXConstructorDecl *Ctor = E->getConstructor()) {
781      bool RequiresZeroInitialization = false;
782      if (Ctor->getParent()->hasTrivialDefaultConstructor()) {
783        // If new expression did not specify value-initialization, then there
784        // is no initialization.
785        if (!E->hasInitializer() || Ctor->getParent()->isEmpty())
786          return;
787
788        if (CGF.CGM.getTypes().isZeroInitializable(E->getAllocatedType())) {
789          // Optimization: since zero initialization will just set the memory
790          // to all zeroes, generate a single memset to do it in one shot.
791          EmitZeroMemSet(CGF, E->getAllocatedType(), NewPtr,
792                         AllocSizeWithoutCookie);
793          return;
794        }
795
796        RequiresZeroInitialization = true;
797      }
798
799      CGF.EmitCXXAggrConstructorCall(Ctor, NumElements, NewPtr,
800                                     E->constructor_arg_begin(),
801                                     E->constructor_arg_end(),
802                                     RequiresZeroInitialization);
803      return;
804    } else if (E->getNumConstructorArgs() == 1 &&
805               isa<ImplicitValueInitExpr>(E->getConstructorArg(0))) {
806      // Optimization: since zero initialization will just set the memory
807      // to all zeroes, generate a single memset to do it in one shot.
808      EmitZeroMemSet(CGF, E->getAllocatedType(), NewPtr,
809                     AllocSizeWithoutCookie);
810      return;
811    } else {
812      CGF.EmitNewArrayInitializer(E, NewPtr, NumElements);
813      return;
814    }
815  }
816
817  if (CXXConstructorDecl *Ctor = E->getConstructor()) {
818    // Per C++ [expr.new]p15, if we have an initializer, then we're performing
819    // direct initialization. C++ [dcl.init]p5 requires that we
820    // zero-initialize storage if there are no user-declared constructors.
821    if (E->hasInitializer() &&
822        !Ctor->getParent()->hasUserDeclaredConstructor() &&
823        !Ctor->getParent()->isEmpty())
824      CGF.EmitNullInitialization(NewPtr, E->getAllocatedType());
825
826    CGF.EmitCXXConstructorCall(Ctor, Ctor_Complete, /*ForVirtualBase=*/false,
827                               NewPtr, E->constructor_arg_begin(),
828                               E->constructor_arg_end());
829
830    return;
831  }
832  // We have a POD type.
833  if (E->getNumConstructorArgs() == 0)
834    return;
835
836  StoreAnyExprIntoOneUnit(CGF, E, NewPtr);
837}
838
839namespace {
840  /// A cleanup to call the given 'operator delete' function upon
841  /// abnormal exit from a new expression.
842  class CallDeleteDuringNew : public EHScopeStack::Cleanup {
843    size_t NumPlacementArgs;
844    const FunctionDecl *OperatorDelete;
845    llvm::Value *Ptr;
846    llvm::Value *AllocSize;
847
848    RValue *getPlacementArgs() { return reinterpret_cast<RValue*>(this+1); }
849
850  public:
851    static size_t getExtraSize(size_t NumPlacementArgs) {
852      return NumPlacementArgs * sizeof(RValue);
853    }
854
855    CallDeleteDuringNew(size_t NumPlacementArgs,
856                        const FunctionDecl *OperatorDelete,
857                        llvm::Value *Ptr,
858                        llvm::Value *AllocSize)
859      : NumPlacementArgs(NumPlacementArgs), OperatorDelete(OperatorDelete),
860        Ptr(Ptr), AllocSize(AllocSize) {}
861
862    void setPlacementArg(unsigned I, RValue Arg) {
863      assert(I < NumPlacementArgs && "index out of range");
864      getPlacementArgs()[I] = Arg;
865    }
866
867    void Emit(CodeGenFunction &CGF, Flags flags) {
868      const FunctionProtoType *FPT
869        = OperatorDelete->getType()->getAs<FunctionProtoType>();
870      assert(FPT->getNumArgs() == NumPlacementArgs + 1 ||
871             (FPT->getNumArgs() == 2 && NumPlacementArgs == 0));
872
873      CallArgList DeleteArgs;
874
875      // The first argument is always a void*.
876      FunctionProtoType::arg_type_iterator AI = FPT->arg_type_begin();
877      DeleteArgs.add(RValue::get(Ptr), *AI++);
878
879      // A member 'operator delete' can take an extra 'size_t' argument.
880      if (FPT->getNumArgs() == NumPlacementArgs + 2)
881        DeleteArgs.add(RValue::get(AllocSize), *AI++);
882
883      // Pass the rest of the arguments, which must match exactly.
884      for (unsigned I = 0; I != NumPlacementArgs; ++I)
885        DeleteArgs.add(getPlacementArgs()[I], *AI++);
886
887      // Call 'operator delete'.
888      CGF.EmitCall(CGF.CGM.getTypes().getFunctionInfo(DeleteArgs, FPT),
889                   CGF.CGM.GetAddrOfFunction(OperatorDelete),
890                   ReturnValueSlot(), DeleteArgs, OperatorDelete);
891    }
892  };
893
894  /// A cleanup to call the given 'operator delete' function upon
895  /// abnormal exit from a new expression when the new expression is
896  /// conditional.
897  class CallDeleteDuringConditionalNew : public EHScopeStack::Cleanup {
898    size_t NumPlacementArgs;
899    const FunctionDecl *OperatorDelete;
900    DominatingValue<RValue>::saved_type Ptr;
901    DominatingValue<RValue>::saved_type AllocSize;
902
903    DominatingValue<RValue>::saved_type *getPlacementArgs() {
904      return reinterpret_cast<DominatingValue<RValue>::saved_type*>(this+1);
905    }
906
907  public:
908    static size_t getExtraSize(size_t NumPlacementArgs) {
909      return NumPlacementArgs * sizeof(DominatingValue<RValue>::saved_type);
910    }
911
912    CallDeleteDuringConditionalNew(size_t NumPlacementArgs,
913                                   const FunctionDecl *OperatorDelete,
914                                   DominatingValue<RValue>::saved_type Ptr,
915                              DominatingValue<RValue>::saved_type AllocSize)
916      : NumPlacementArgs(NumPlacementArgs), OperatorDelete(OperatorDelete),
917        Ptr(Ptr), AllocSize(AllocSize) {}
918
919    void setPlacementArg(unsigned I, DominatingValue<RValue>::saved_type Arg) {
920      assert(I < NumPlacementArgs && "index out of range");
921      getPlacementArgs()[I] = Arg;
922    }
923
924    void Emit(CodeGenFunction &CGF, Flags flags) {
925      const FunctionProtoType *FPT
926        = OperatorDelete->getType()->getAs<FunctionProtoType>();
927      assert(FPT->getNumArgs() == NumPlacementArgs + 1 ||
928             (FPT->getNumArgs() == 2 && NumPlacementArgs == 0));
929
930      CallArgList DeleteArgs;
931
932      // The first argument is always a void*.
933      FunctionProtoType::arg_type_iterator AI = FPT->arg_type_begin();
934      DeleteArgs.add(Ptr.restore(CGF), *AI++);
935
936      // A member 'operator delete' can take an extra 'size_t' argument.
937      if (FPT->getNumArgs() == NumPlacementArgs + 2) {
938        RValue RV = AllocSize.restore(CGF);
939        DeleteArgs.add(RV, *AI++);
940      }
941
942      // Pass the rest of the arguments, which must match exactly.
943      for (unsigned I = 0; I != NumPlacementArgs; ++I) {
944        RValue RV = getPlacementArgs()[I].restore(CGF);
945        DeleteArgs.add(RV, *AI++);
946      }
947
948      // Call 'operator delete'.
949      CGF.EmitCall(CGF.CGM.getTypes().getFunctionInfo(DeleteArgs, FPT),
950                   CGF.CGM.GetAddrOfFunction(OperatorDelete),
951                   ReturnValueSlot(), DeleteArgs, OperatorDelete);
952    }
953  };
954}
955
956/// Enter a cleanup to call 'operator delete' if the initializer in a
957/// new-expression throws.
958static void EnterNewDeleteCleanup(CodeGenFunction &CGF,
959                                  const CXXNewExpr *E,
960                                  llvm::Value *NewPtr,
961                                  llvm::Value *AllocSize,
962                                  const CallArgList &NewArgs) {
963  // If we're not inside a conditional branch, then the cleanup will
964  // dominate and we can do the easier (and more efficient) thing.
965  if (!CGF.isInConditionalBranch()) {
966    CallDeleteDuringNew *Cleanup = CGF.EHStack
967      .pushCleanupWithExtra<CallDeleteDuringNew>(EHCleanup,
968                                                 E->getNumPlacementArgs(),
969                                                 E->getOperatorDelete(),
970                                                 NewPtr, AllocSize);
971    for (unsigned I = 0, N = E->getNumPlacementArgs(); I != N; ++I)
972      Cleanup->setPlacementArg(I, NewArgs[I+1].RV);
973
974    return;
975  }
976
977  // Otherwise, we need to save all this stuff.
978  DominatingValue<RValue>::saved_type SavedNewPtr =
979    DominatingValue<RValue>::save(CGF, RValue::get(NewPtr));
980  DominatingValue<RValue>::saved_type SavedAllocSize =
981    DominatingValue<RValue>::save(CGF, RValue::get(AllocSize));
982
983  CallDeleteDuringConditionalNew *Cleanup = CGF.EHStack
984    .pushCleanupWithExtra<CallDeleteDuringConditionalNew>(InactiveEHCleanup,
985                                                 E->getNumPlacementArgs(),
986                                                 E->getOperatorDelete(),
987                                                 SavedNewPtr,
988                                                 SavedAllocSize);
989  for (unsigned I = 0, N = E->getNumPlacementArgs(); I != N; ++I)
990    Cleanup->setPlacementArg(I,
991                     DominatingValue<RValue>::save(CGF, NewArgs[I+1].RV));
992
993  CGF.ActivateCleanupBlock(CGF.EHStack.stable_begin());
994}
995
996llvm::Value *CodeGenFunction::EmitCXXNewExpr(const CXXNewExpr *E) {
997  // The element type being allocated.
998  QualType allocType = getContext().getBaseElementType(E->getAllocatedType());
999
1000  // 1. Build a call to the allocation function.
1001  FunctionDecl *allocator = E->getOperatorNew();
1002  const FunctionProtoType *allocatorType =
1003    allocator->getType()->castAs<FunctionProtoType>();
1004
1005  CallArgList allocatorArgs;
1006
1007  // The allocation size is the first argument.
1008  QualType sizeType = getContext().getSizeType();
1009
1010  llvm::Value *numElements = 0;
1011  llvm::Value *allocSizeWithoutCookie = 0;
1012  llvm::Value *allocSize =
1013    EmitCXXNewAllocSize(*this, E, numElements, allocSizeWithoutCookie);
1014
1015  allocatorArgs.add(RValue::get(allocSize), sizeType);
1016
1017  // Emit the rest of the arguments.
1018  // FIXME: Ideally, this should just use EmitCallArgs.
1019  CXXNewExpr::const_arg_iterator placementArg = E->placement_arg_begin();
1020
1021  // First, use the types from the function type.
1022  // We start at 1 here because the first argument (the allocation size)
1023  // has already been emitted.
1024  for (unsigned i = 1, e = allocatorType->getNumArgs(); i != e;
1025       ++i, ++placementArg) {
1026    QualType argType = allocatorType->getArgType(i);
1027
1028    assert(getContext().hasSameUnqualifiedType(argType.getNonReferenceType(),
1029                                               placementArg->getType()) &&
1030           "type mismatch in call argument!");
1031
1032    EmitCallArg(allocatorArgs, *placementArg, argType);
1033  }
1034
1035  // Either we've emitted all the call args, or we have a call to a
1036  // variadic function.
1037  assert((placementArg == E->placement_arg_end() ||
1038          allocatorType->isVariadic()) &&
1039         "Extra arguments to non-variadic function!");
1040
1041  // If we still have any arguments, emit them using the type of the argument.
1042  for (CXXNewExpr::const_arg_iterator placementArgsEnd = E->placement_arg_end();
1043       placementArg != placementArgsEnd; ++placementArg) {
1044    EmitCallArg(allocatorArgs, *placementArg, placementArg->getType());
1045  }
1046
1047  // Emit the allocation call.  If the allocator is a global placement
1048  // operator, just "inline" it directly.
1049  RValue RV;
1050  if (allocator->isReservedGlobalPlacementOperator()) {
1051    assert(allocatorArgs.size() == 2);
1052    RV = allocatorArgs[1].RV;
1053    // TODO: kill any unnecessary computations done for the size
1054    // argument.
1055  } else {
1056    RV = EmitCall(CGM.getTypes().getFunctionInfo(allocatorArgs, allocatorType),
1057                  CGM.GetAddrOfFunction(allocator), ReturnValueSlot(),
1058                  allocatorArgs, allocator);
1059  }
1060
1061  // Emit a null check on the allocation result if the allocation
1062  // function is allowed to return null (because it has a non-throwing
1063  // exception spec; for this part, we inline
1064  // CXXNewExpr::shouldNullCheckAllocation()) and we have an
1065  // interesting initializer.
1066  bool nullCheck = allocatorType->isNothrow(getContext()) &&
1067    !(allocType.isPODType(getContext()) && !E->hasInitializer());
1068
1069  llvm::BasicBlock *nullCheckBB = 0;
1070  llvm::BasicBlock *contBB = 0;
1071
1072  llvm::Value *allocation = RV.getScalarVal();
1073  unsigned AS =
1074    cast<llvm::PointerType>(allocation->getType())->getAddressSpace();
1075
1076  // The null-check means that the initializer is conditionally
1077  // evaluated.
1078  ConditionalEvaluation conditional(*this);
1079
1080  if (nullCheck) {
1081    conditional.begin(*this);
1082
1083    nullCheckBB = Builder.GetInsertBlock();
1084    llvm::BasicBlock *notNullBB = createBasicBlock("new.notnull");
1085    contBB = createBasicBlock("new.cont");
1086
1087    llvm::Value *isNull = Builder.CreateIsNull(allocation, "new.isnull");
1088    Builder.CreateCondBr(isNull, contBB, notNullBB);
1089    EmitBlock(notNullBB);
1090  }
1091
1092  assert((allocSize == allocSizeWithoutCookie) ==
1093         CalculateCookiePadding(*this, E).isZero());
1094  if (allocSize != allocSizeWithoutCookie) {
1095    assert(E->isArray());
1096    allocation = CGM.getCXXABI().InitializeArrayCookie(*this, allocation,
1097                                                       numElements,
1098                                                       E, allocType);
1099  }
1100
1101  // If there's an operator delete, enter a cleanup to call it if an
1102  // exception is thrown.
1103  EHScopeStack::stable_iterator operatorDeleteCleanup;
1104  if (E->getOperatorDelete() &&
1105      !E->getOperatorDelete()->isReservedGlobalPlacementOperator()) {
1106    EnterNewDeleteCleanup(*this, E, allocation, allocSize, allocatorArgs);
1107    operatorDeleteCleanup = EHStack.stable_begin();
1108  }
1109
1110  llvm::Type *elementPtrTy
1111    = ConvertTypeForMem(allocType)->getPointerTo(AS);
1112  llvm::Value *result = Builder.CreateBitCast(allocation, elementPtrTy);
1113
1114  if (E->isArray()) {
1115    EmitNewInitializer(*this, E, result, numElements, allocSizeWithoutCookie);
1116
1117    // NewPtr is a pointer to the base element type.  If we're
1118    // allocating an array of arrays, we'll need to cast back to the
1119    // array pointer type.
1120    llvm::Type *resultType = ConvertTypeForMem(E->getType());
1121    if (result->getType() != resultType)
1122      result = Builder.CreateBitCast(result, resultType);
1123  } else {
1124    EmitNewInitializer(*this, E, result, numElements, allocSizeWithoutCookie);
1125  }
1126
1127  // Deactivate the 'operator delete' cleanup if we finished
1128  // initialization.
1129  if (operatorDeleteCleanup.isValid())
1130    DeactivateCleanupBlock(operatorDeleteCleanup);
1131
1132  if (nullCheck) {
1133    conditional.end(*this);
1134
1135    llvm::BasicBlock *notNullBB = Builder.GetInsertBlock();
1136    EmitBlock(contBB);
1137
1138    llvm::PHINode *PHI = Builder.CreatePHI(result->getType(), 2);
1139    PHI->addIncoming(result, notNullBB);
1140    PHI->addIncoming(llvm::Constant::getNullValue(result->getType()),
1141                     nullCheckBB);
1142
1143    result = PHI;
1144  }
1145
1146  return result;
1147}
1148
1149void CodeGenFunction::EmitDeleteCall(const FunctionDecl *DeleteFD,
1150                                     llvm::Value *Ptr,
1151                                     QualType DeleteTy) {
1152  assert(DeleteFD->getOverloadedOperator() == OO_Delete);
1153
1154  const FunctionProtoType *DeleteFTy =
1155    DeleteFD->getType()->getAs<FunctionProtoType>();
1156
1157  CallArgList DeleteArgs;
1158
1159  // Check if we need to pass the size to the delete operator.
1160  llvm::Value *Size = 0;
1161  QualType SizeTy;
1162  if (DeleteFTy->getNumArgs() == 2) {
1163    SizeTy = DeleteFTy->getArgType(1);
1164    CharUnits DeleteTypeSize = getContext().getTypeSizeInChars(DeleteTy);
1165    Size = llvm::ConstantInt::get(ConvertType(SizeTy),
1166                                  DeleteTypeSize.getQuantity());
1167  }
1168
1169  QualType ArgTy = DeleteFTy->getArgType(0);
1170  llvm::Value *DeletePtr = Builder.CreateBitCast(Ptr, ConvertType(ArgTy));
1171  DeleteArgs.add(RValue::get(DeletePtr), ArgTy);
1172
1173  if (Size)
1174    DeleteArgs.add(RValue::get(Size), SizeTy);
1175
1176  // Emit the call to delete.
1177  EmitCall(CGM.getTypes().getFunctionInfo(DeleteArgs, DeleteFTy),
1178           CGM.GetAddrOfFunction(DeleteFD), ReturnValueSlot(),
1179           DeleteArgs, DeleteFD);
1180}
1181
1182namespace {
1183  /// Calls the given 'operator delete' on a single object.
1184  struct CallObjectDelete : EHScopeStack::Cleanup {
1185    llvm::Value *Ptr;
1186    const FunctionDecl *OperatorDelete;
1187    QualType ElementType;
1188
1189    CallObjectDelete(llvm::Value *Ptr,
1190                     const FunctionDecl *OperatorDelete,
1191                     QualType ElementType)
1192      : Ptr(Ptr), OperatorDelete(OperatorDelete), ElementType(ElementType) {}
1193
1194    void Emit(CodeGenFunction &CGF, Flags flags) {
1195      CGF.EmitDeleteCall(OperatorDelete, Ptr, ElementType);
1196    }
1197  };
1198}
1199
1200/// Emit the code for deleting a single object.
1201static void EmitObjectDelete(CodeGenFunction &CGF,
1202                             const FunctionDecl *OperatorDelete,
1203                             llvm::Value *Ptr,
1204                             QualType ElementType,
1205                             bool UseGlobalDelete) {
1206  // Find the destructor for the type, if applicable.  If the
1207  // destructor is virtual, we'll just emit the vcall and return.
1208  const CXXDestructorDecl *Dtor = 0;
1209  if (const RecordType *RT = ElementType->getAs<RecordType>()) {
1210    CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
1211    if (RD->hasDefinition() && !RD->hasTrivialDestructor()) {
1212      Dtor = RD->getDestructor();
1213
1214      if (Dtor->isVirtual()) {
1215        if (UseGlobalDelete) {
1216          // If we're supposed to call the global delete, make sure we do so
1217          // even if the destructor throws.
1218          CGF.EHStack.pushCleanup<CallObjectDelete>(NormalAndEHCleanup,
1219                                                    Ptr, OperatorDelete,
1220                                                    ElementType);
1221        }
1222
1223        llvm::Type *Ty =
1224          CGF.getTypes().GetFunctionType(CGF.getTypes().getFunctionInfo(Dtor,
1225                                                               Dtor_Complete),
1226                                         /*isVariadic=*/false);
1227
1228        llvm::Value *Callee
1229          = CGF.BuildVirtualCall(Dtor,
1230                                 UseGlobalDelete? Dtor_Complete : Dtor_Deleting,
1231                                 Ptr, Ty);
1232        CGF.EmitCXXMemberCall(Dtor, Callee, ReturnValueSlot(), Ptr, /*VTT=*/0,
1233                              0, 0);
1234
1235        if (UseGlobalDelete) {
1236          CGF.PopCleanupBlock();
1237        }
1238
1239        return;
1240      }
1241    }
1242  }
1243
1244  // Make sure that we call delete even if the dtor throws.
1245  // This doesn't have to a conditional cleanup because we're going
1246  // to pop it off in a second.
1247  CGF.EHStack.pushCleanup<CallObjectDelete>(NormalAndEHCleanup,
1248                                            Ptr, OperatorDelete, ElementType);
1249
1250  if (Dtor)
1251    CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
1252                              /*ForVirtualBase=*/false, Ptr);
1253  else if (CGF.getLangOptions().ObjCAutoRefCount &&
1254           ElementType->isObjCLifetimeType()) {
1255    switch (ElementType.getObjCLifetime()) {
1256    case Qualifiers::OCL_None:
1257    case Qualifiers::OCL_ExplicitNone:
1258    case Qualifiers::OCL_Autoreleasing:
1259      break;
1260
1261    case Qualifiers::OCL_Strong: {
1262      // Load the pointer value.
1263      llvm::Value *PtrValue = CGF.Builder.CreateLoad(Ptr,
1264                                             ElementType.isVolatileQualified());
1265
1266      CGF.EmitARCRelease(PtrValue, /*precise*/ true);
1267      break;
1268    }
1269
1270    case Qualifiers::OCL_Weak:
1271      CGF.EmitARCDestroyWeak(Ptr);
1272      break;
1273    }
1274  }
1275
1276  CGF.PopCleanupBlock();
1277}
1278
1279namespace {
1280  /// Calls the given 'operator delete' on an array of objects.
1281  struct CallArrayDelete : EHScopeStack::Cleanup {
1282    llvm::Value *Ptr;
1283    const FunctionDecl *OperatorDelete;
1284    llvm::Value *NumElements;
1285    QualType ElementType;
1286    CharUnits CookieSize;
1287
1288    CallArrayDelete(llvm::Value *Ptr,
1289                    const FunctionDecl *OperatorDelete,
1290                    llvm::Value *NumElements,
1291                    QualType ElementType,
1292                    CharUnits CookieSize)
1293      : Ptr(Ptr), OperatorDelete(OperatorDelete), NumElements(NumElements),
1294        ElementType(ElementType), CookieSize(CookieSize) {}
1295
1296    void Emit(CodeGenFunction &CGF, Flags flags) {
1297      const FunctionProtoType *DeleteFTy =
1298        OperatorDelete->getType()->getAs<FunctionProtoType>();
1299      assert(DeleteFTy->getNumArgs() == 1 || DeleteFTy->getNumArgs() == 2);
1300
1301      CallArgList Args;
1302
1303      // Pass the pointer as the first argument.
1304      QualType VoidPtrTy = DeleteFTy->getArgType(0);
1305      llvm::Value *DeletePtr
1306        = CGF.Builder.CreateBitCast(Ptr, CGF.ConvertType(VoidPtrTy));
1307      Args.add(RValue::get(DeletePtr), VoidPtrTy);
1308
1309      // Pass the original requested size as the second argument.
1310      if (DeleteFTy->getNumArgs() == 2) {
1311        QualType size_t = DeleteFTy->getArgType(1);
1312        llvm::IntegerType *SizeTy
1313          = cast<llvm::IntegerType>(CGF.ConvertType(size_t));
1314
1315        CharUnits ElementTypeSize =
1316          CGF.CGM.getContext().getTypeSizeInChars(ElementType);
1317
1318        // The size of an element, multiplied by the number of elements.
1319        llvm::Value *Size
1320          = llvm::ConstantInt::get(SizeTy, ElementTypeSize.getQuantity());
1321        Size = CGF.Builder.CreateMul(Size, NumElements);
1322
1323        // Plus the size of the cookie if applicable.
1324        if (!CookieSize.isZero()) {
1325          llvm::Value *CookieSizeV
1326            = llvm::ConstantInt::get(SizeTy, CookieSize.getQuantity());
1327          Size = CGF.Builder.CreateAdd(Size, CookieSizeV);
1328        }
1329
1330        Args.add(RValue::get(Size), size_t);
1331      }
1332
1333      // Emit the call to delete.
1334      CGF.EmitCall(CGF.getTypes().getFunctionInfo(Args, DeleteFTy),
1335                   CGF.CGM.GetAddrOfFunction(OperatorDelete),
1336                   ReturnValueSlot(), Args, OperatorDelete);
1337    }
1338  };
1339}
1340
1341/// Emit the code for deleting an array of objects.
1342static void EmitArrayDelete(CodeGenFunction &CGF,
1343                            const CXXDeleteExpr *E,
1344                            llvm::Value *deletedPtr,
1345                            QualType elementType) {
1346  llvm::Value *numElements = 0;
1347  llvm::Value *allocatedPtr = 0;
1348  CharUnits cookieSize;
1349  CGF.CGM.getCXXABI().ReadArrayCookie(CGF, deletedPtr, E, elementType,
1350                                      numElements, allocatedPtr, cookieSize);
1351
1352  assert(allocatedPtr && "ReadArrayCookie didn't set allocated pointer");
1353
1354  // Make sure that we call delete even if one of the dtors throws.
1355  const FunctionDecl *operatorDelete = E->getOperatorDelete();
1356  CGF.EHStack.pushCleanup<CallArrayDelete>(NormalAndEHCleanup,
1357                                           allocatedPtr, operatorDelete,
1358                                           numElements, elementType,
1359                                           cookieSize);
1360
1361  // Destroy the elements.
1362  if (QualType::DestructionKind dtorKind = elementType.isDestructedType()) {
1363    assert(numElements && "no element count for a type with a destructor!");
1364
1365    llvm::Value *arrayEnd =
1366      CGF.Builder.CreateInBoundsGEP(deletedPtr, numElements, "delete.end");
1367
1368    // Note that it is legal to allocate a zero-length array, and we
1369    // can never fold the check away because the length should always
1370    // come from a cookie.
1371    CGF.emitArrayDestroy(deletedPtr, arrayEnd, elementType,
1372                         CGF.getDestroyer(dtorKind),
1373                         /*checkZeroLength*/ true,
1374                         CGF.needsEHCleanup(dtorKind));
1375  }
1376
1377  // Pop the cleanup block.
1378  CGF.PopCleanupBlock();
1379}
1380
1381void CodeGenFunction::EmitCXXDeleteExpr(const CXXDeleteExpr *E) {
1382
1383  // Get at the argument before we performed the implicit conversion
1384  // to void*.
1385  const Expr *Arg = E->getArgument();
1386  while (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg)) {
1387    if (ICE->getCastKind() != CK_UserDefinedConversion &&
1388        ICE->getType()->isVoidPointerType())
1389      Arg = ICE->getSubExpr();
1390    else
1391      break;
1392  }
1393
1394  llvm::Value *Ptr = EmitScalarExpr(Arg);
1395
1396  // Null check the pointer.
1397  llvm::BasicBlock *DeleteNotNull = createBasicBlock("delete.notnull");
1398  llvm::BasicBlock *DeleteEnd = createBasicBlock("delete.end");
1399
1400  llvm::Value *IsNull = Builder.CreateIsNull(Ptr, "isnull");
1401
1402  Builder.CreateCondBr(IsNull, DeleteEnd, DeleteNotNull);
1403  EmitBlock(DeleteNotNull);
1404
1405  // We might be deleting a pointer to array.  If so, GEP down to the
1406  // first non-array element.
1407  // (this assumes that A(*)[3][7] is converted to [3 x [7 x %A]]*)
1408  QualType DeleteTy = Arg->getType()->getAs<PointerType>()->getPointeeType();
1409  if (DeleteTy->isConstantArrayType()) {
1410    llvm::Value *Zero = Builder.getInt32(0);
1411    SmallVector<llvm::Value*,8> GEP;
1412
1413    GEP.push_back(Zero); // point at the outermost array
1414
1415    // For each layer of array type we're pointing at:
1416    while (const ConstantArrayType *Arr
1417             = getContext().getAsConstantArrayType(DeleteTy)) {
1418      // 1. Unpeel the array type.
1419      DeleteTy = Arr->getElementType();
1420
1421      // 2. GEP to the first element of the array.
1422      GEP.push_back(Zero);
1423    }
1424
1425    Ptr = Builder.CreateInBoundsGEP(Ptr, GEP, "del.first");
1426  }
1427
1428  assert(ConvertTypeForMem(DeleteTy) ==
1429         cast<llvm::PointerType>(Ptr->getType())->getElementType());
1430
1431  if (E->isArrayForm()) {
1432    EmitArrayDelete(*this, E, Ptr, DeleteTy);
1433  } else {
1434    EmitObjectDelete(*this, E->getOperatorDelete(), Ptr, DeleteTy,
1435                     E->isGlobalDelete());
1436  }
1437
1438  EmitBlock(DeleteEnd);
1439}
1440
1441static llvm::Constant *getBadTypeidFn(CodeGenFunction &CGF) {
1442  // void __cxa_bad_typeid();
1443
1444  llvm::Type *VoidTy = llvm::Type::getVoidTy(CGF.getLLVMContext());
1445  llvm::FunctionType *FTy =
1446  llvm::FunctionType::get(VoidTy, false);
1447
1448  return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_bad_typeid");
1449}
1450
1451static void EmitBadTypeidCall(CodeGenFunction &CGF) {
1452  llvm::Value *Fn = getBadTypeidFn(CGF);
1453  CGF.EmitCallOrInvoke(Fn).setDoesNotReturn();
1454  CGF.Builder.CreateUnreachable();
1455}
1456
1457static llvm::Value *EmitTypeidFromVTable(CodeGenFunction &CGF,
1458                                         const Expr *E,
1459                                         llvm::Type *StdTypeInfoPtrTy) {
1460  // Get the vtable pointer.
1461  llvm::Value *ThisPtr = CGF.EmitLValue(E).getAddress();
1462
1463  // C++ [expr.typeid]p2:
1464  //   If the glvalue expression is obtained by applying the unary * operator to
1465  //   a pointer and the pointer is a null pointer value, the typeid expression
1466  //   throws the std::bad_typeid exception.
1467  if (const UnaryOperator *UO = dyn_cast<UnaryOperator>(E->IgnoreParens())) {
1468    if (UO->getOpcode() == UO_Deref) {
1469      llvm::BasicBlock *BadTypeidBlock =
1470        CGF.createBasicBlock("typeid.bad_typeid");
1471      llvm::BasicBlock *EndBlock =
1472        CGF.createBasicBlock("typeid.end");
1473
1474      llvm::Value *IsNull = CGF.Builder.CreateIsNull(ThisPtr);
1475      CGF.Builder.CreateCondBr(IsNull, BadTypeidBlock, EndBlock);
1476
1477      CGF.EmitBlock(BadTypeidBlock);
1478      EmitBadTypeidCall(CGF);
1479      CGF.EmitBlock(EndBlock);
1480    }
1481  }
1482
1483  llvm::Value *Value = CGF.GetVTablePtr(ThisPtr,
1484                                        StdTypeInfoPtrTy->getPointerTo());
1485
1486  // Load the type info.
1487  Value = CGF.Builder.CreateConstInBoundsGEP1_64(Value, -1ULL);
1488  return CGF.Builder.CreateLoad(Value);
1489}
1490
1491llvm::Value *CodeGenFunction::EmitCXXTypeidExpr(const CXXTypeidExpr *E) {
1492  llvm::Type *StdTypeInfoPtrTy =
1493    ConvertType(E->getType())->getPointerTo();
1494
1495  if (E->isTypeOperand()) {
1496    llvm::Constant *TypeInfo =
1497      CGM.GetAddrOfRTTIDescriptor(E->getTypeOperand());
1498    return Builder.CreateBitCast(TypeInfo, StdTypeInfoPtrTy);
1499  }
1500
1501  // C++ [expr.typeid]p2:
1502  //   When typeid is applied to a glvalue expression whose type is a
1503  //   polymorphic class type, the result refers to a std::type_info object
1504  //   representing the type of the most derived object (that is, the dynamic
1505  //   type) to which the glvalue refers.
1506  if (E->getExprOperand()->isGLValue()) {
1507    if (const RecordType *RT =
1508          E->getExprOperand()->getType()->getAs<RecordType>()) {
1509      const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
1510      if (RD->isPolymorphic())
1511        return EmitTypeidFromVTable(*this, E->getExprOperand(),
1512                                    StdTypeInfoPtrTy);
1513    }
1514  }
1515
1516  QualType OperandTy = E->getExprOperand()->getType();
1517  return Builder.CreateBitCast(CGM.GetAddrOfRTTIDescriptor(OperandTy),
1518                               StdTypeInfoPtrTy);
1519}
1520
1521static llvm::Constant *getDynamicCastFn(CodeGenFunction &CGF) {
1522  // void *__dynamic_cast(const void *sub,
1523  //                      const abi::__class_type_info *src,
1524  //                      const abi::__class_type_info *dst,
1525  //                      std::ptrdiff_t src2dst_offset);
1526
1527  llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
1528  llvm::Type *PtrDiffTy =
1529    CGF.ConvertType(CGF.getContext().getPointerDiffType());
1530
1531  llvm::Type *Args[4] = { Int8PtrTy, Int8PtrTy, Int8PtrTy, PtrDiffTy };
1532
1533  llvm::FunctionType *FTy =
1534    llvm::FunctionType::get(Int8PtrTy, Args, false);
1535
1536  return CGF.CGM.CreateRuntimeFunction(FTy, "__dynamic_cast");
1537}
1538
1539static llvm::Constant *getBadCastFn(CodeGenFunction &CGF) {
1540  // void __cxa_bad_cast();
1541
1542  llvm::Type *VoidTy = llvm::Type::getVoidTy(CGF.getLLVMContext());
1543  llvm::FunctionType *FTy =
1544    llvm::FunctionType::get(VoidTy, false);
1545
1546  return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_bad_cast");
1547}
1548
1549static void EmitBadCastCall(CodeGenFunction &CGF) {
1550  llvm::Value *Fn = getBadCastFn(CGF);
1551  CGF.EmitCallOrInvoke(Fn).setDoesNotReturn();
1552  CGF.Builder.CreateUnreachable();
1553}
1554
1555static llvm::Value *
1556EmitDynamicCastCall(CodeGenFunction &CGF, llvm::Value *Value,
1557                    QualType SrcTy, QualType DestTy,
1558                    llvm::BasicBlock *CastEnd) {
1559  llvm::Type *PtrDiffLTy =
1560    CGF.ConvertType(CGF.getContext().getPointerDiffType());
1561  llvm::Type *DestLTy = CGF.ConvertType(DestTy);
1562
1563  if (const PointerType *PTy = DestTy->getAs<PointerType>()) {
1564    if (PTy->getPointeeType()->isVoidType()) {
1565      // C++ [expr.dynamic.cast]p7:
1566      //   If T is "pointer to cv void," then the result is a pointer to the
1567      //   most derived object pointed to by v.
1568
1569      // Get the vtable pointer.
1570      llvm::Value *VTable = CGF.GetVTablePtr(Value, PtrDiffLTy->getPointerTo());
1571
1572      // Get the offset-to-top from the vtable.
1573      llvm::Value *OffsetToTop =
1574        CGF.Builder.CreateConstInBoundsGEP1_64(VTable, -2ULL);
1575      OffsetToTop = CGF.Builder.CreateLoad(OffsetToTop, "offset.to.top");
1576
1577      // Finally, add the offset to the pointer.
1578      Value = CGF.EmitCastToVoidPtr(Value);
1579      Value = CGF.Builder.CreateInBoundsGEP(Value, OffsetToTop);
1580
1581      return CGF.Builder.CreateBitCast(Value, DestLTy);
1582    }
1583  }
1584
1585  QualType SrcRecordTy;
1586  QualType DestRecordTy;
1587
1588  if (const PointerType *DestPTy = DestTy->getAs<PointerType>()) {
1589    SrcRecordTy = SrcTy->castAs<PointerType>()->getPointeeType();
1590    DestRecordTy = DestPTy->getPointeeType();
1591  } else {
1592    SrcRecordTy = SrcTy;
1593    DestRecordTy = DestTy->castAs<ReferenceType>()->getPointeeType();
1594  }
1595
1596  assert(SrcRecordTy->isRecordType() && "source type must be a record type!");
1597  assert(DestRecordTy->isRecordType() && "dest type must be a record type!");
1598
1599  llvm::Value *SrcRTTI =
1600    CGF.CGM.GetAddrOfRTTIDescriptor(SrcRecordTy.getUnqualifiedType());
1601  llvm::Value *DestRTTI =
1602    CGF.CGM.GetAddrOfRTTIDescriptor(DestRecordTy.getUnqualifiedType());
1603
1604  // FIXME: Actually compute a hint here.
1605  llvm::Value *OffsetHint = llvm::ConstantInt::get(PtrDiffLTy, -1ULL);
1606
1607  // Emit the call to __dynamic_cast.
1608  Value = CGF.EmitCastToVoidPtr(Value);
1609  Value = CGF.Builder.CreateCall4(getDynamicCastFn(CGF), Value,
1610                                  SrcRTTI, DestRTTI, OffsetHint);
1611  Value = CGF.Builder.CreateBitCast(Value, DestLTy);
1612
1613  /// C++ [expr.dynamic.cast]p9:
1614  ///   A failed cast to reference type throws std::bad_cast
1615  if (DestTy->isReferenceType()) {
1616    llvm::BasicBlock *BadCastBlock =
1617      CGF.createBasicBlock("dynamic_cast.bad_cast");
1618
1619    llvm::Value *IsNull = CGF.Builder.CreateIsNull(Value);
1620    CGF.Builder.CreateCondBr(IsNull, BadCastBlock, CastEnd);
1621
1622    CGF.EmitBlock(BadCastBlock);
1623    EmitBadCastCall(CGF);
1624  }
1625
1626  return Value;
1627}
1628
1629static llvm::Value *EmitDynamicCastToNull(CodeGenFunction &CGF,
1630                                          QualType DestTy) {
1631  llvm::Type *DestLTy = CGF.ConvertType(DestTy);
1632  if (DestTy->isPointerType())
1633    return llvm::Constant::getNullValue(DestLTy);
1634
1635  /// C++ [expr.dynamic.cast]p9:
1636  ///   A failed cast to reference type throws std::bad_cast
1637  EmitBadCastCall(CGF);
1638
1639  CGF.EmitBlock(CGF.createBasicBlock("dynamic_cast.end"));
1640  return llvm::UndefValue::get(DestLTy);
1641}
1642
1643llvm::Value *CodeGenFunction::EmitDynamicCast(llvm::Value *Value,
1644                                              const CXXDynamicCastExpr *DCE) {
1645  QualType DestTy = DCE->getTypeAsWritten();
1646
1647  if (DCE->isAlwaysNull())
1648    return EmitDynamicCastToNull(*this, DestTy);
1649
1650  QualType SrcTy = DCE->getSubExpr()->getType();
1651
1652  // C++ [expr.dynamic.cast]p4:
1653  //   If the value of v is a null pointer value in the pointer case, the result
1654  //   is the null pointer value of type T.
1655  bool ShouldNullCheckSrcValue = SrcTy->isPointerType();
1656
1657  llvm::BasicBlock *CastNull = 0;
1658  llvm::BasicBlock *CastNotNull = 0;
1659  llvm::BasicBlock *CastEnd = createBasicBlock("dynamic_cast.end");
1660
1661  if (ShouldNullCheckSrcValue) {
1662    CastNull = createBasicBlock("dynamic_cast.null");
1663    CastNotNull = createBasicBlock("dynamic_cast.notnull");
1664
1665    llvm::Value *IsNull = Builder.CreateIsNull(Value);
1666    Builder.CreateCondBr(IsNull, CastNull, CastNotNull);
1667    EmitBlock(CastNotNull);
1668  }
1669
1670  Value = EmitDynamicCastCall(*this, Value, SrcTy, DestTy, CastEnd);
1671
1672  if (ShouldNullCheckSrcValue) {
1673    EmitBranch(CastEnd);
1674
1675    EmitBlock(CastNull);
1676    EmitBranch(CastEnd);
1677  }
1678
1679  EmitBlock(CastEnd);
1680
1681  if (ShouldNullCheckSrcValue) {
1682    llvm::PHINode *PHI = Builder.CreatePHI(Value->getType(), 2);
1683    PHI->addIncoming(Value, CastNotNull);
1684    PHI->addIncoming(llvm::Constant::getNullValue(Value->getType()), CastNull);
1685
1686    Value = PHI;
1687  }
1688
1689  return Value;
1690}
1691