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 "CGCUDARuntime.h"
17 #include "CGCXXABI.h"
18 #include "CGObjCRuntime.h"
19 #include "CGDebugInfo.h"
20 #include "llvm/Intrinsics.h"
21 #include "llvm/Support/CallSite.h"
22 
23 using namespace clang;
24 using namespace CodeGen;
25 
26 RValue CodeGenFunction::EmitCXXMemberCall(const CXXMethodDecl *MD,
27                                           llvm::Value *Callee,
28                                           ReturnValueSlot ReturnValue,
29                                           llvm::Value *This,
30                                           llvm::Value *VTT,
31                                           CallExpr::const_arg_iterator ArgBeg,
32                                           CallExpr::const_arg_iterator ArgEnd) {
33   assert(MD->isInstance() &&
34          "Trying to emit a member call expr on a static method!");
35 
36   CallArgList Args;
37 
38   // Push the this ptr.
39   Args.add(RValue::get(This), MD->getThisType(getContext()));
40 
41   // If there is a VTT parameter, emit it.
42   if (VTT) {
43     QualType T = getContext().getPointerType(getContext().VoidPtrTy);
44     Args.add(RValue::get(VTT), T);
45   }
46 
47   const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>();
48   RequiredArgs required = RequiredArgs::forPrototypePlus(FPT, Args.size());
49 
50   // And the rest of the call args.
51   EmitCallArgs(Args, FPT, ArgBeg, ArgEnd);
52 
53   return EmitCall(CGM.getTypes().arrangeFunctionCall(FPT->getResultType(), Args,
54                                                      FPT->getExtInfo(),
55                                                      required),
56                   Callee, ReturnValue, Args, MD);
57 }
58 
59 static const CXXRecordDecl *getMostDerivedClassDecl(const Expr *Base) {
60   const Expr *E = Base;
61 
62   while (true) {
63     E = E->IgnoreParens();
64     if (const CastExpr *CE = dyn_cast<CastExpr>(E)) {
65       if (CE->getCastKind() == CK_DerivedToBase ||
66           CE->getCastKind() == CK_UncheckedDerivedToBase ||
67           CE->getCastKind() == CK_NoOp) {
68         E = CE->getSubExpr();
69         continue;
70       }
71     }
72 
73     break;
74   }
75 
76   QualType DerivedType = E->getType();
77   if (const PointerType *PTy = DerivedType->getAs<PointerType>())
78     DerivedType = PTy->getPointeeType();
79 
80   return cast<CXXRecordDecl>(DerivedType->castAs<RecordType>()->getDecl());
81 }
82 
83 // FIXME: Ideally Expr::IgnoreParenNoopCasts should do this, but it doesn't do
84 // quite what we want.
85 static const Expr *skipNoOpCastsAndParens(const Expr *E) {
86   while (true) {
87     if (const ParenExpr *PE = dyn_cast<ParenExpr>(E)) {
88       E = PE->getSubExpr();
89       continue;
90     }
91 
92     if (const CastExpr *CE = dyn_cast<CastExpr>(E)) {
93       if (CE->getCastKind() == CK_NoOp) {
94         E = CE->getSubExpr();
95         continue;
96       }
97     }
98     if (const UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
99       if (UO->getOpcode() == UO_Extension) {
100         E = UO->getSubExpr();
101         continue;
102       }
103     }
104     return E;
105   }
106 }
107 
108 /// canDevirtualizeMemberFunctionCalls - Checks whether virtual calls on given
109 /// expr can be devirtualized.
110 static bool canDevirtualizeMemberFunctionCalls(ASTContext &Context,
111                                                const Expr *Base,
112                                                const CXXMethodDecl *MD) {
113 
114   // When building with -fapple-kext, all calls must go through the vtable since
115   // the kernel linker can do runtime patching of vtables.
116   if (Context.getLangOpts().AppleKext)
117     return false;
118 
119   // If the most derived class is marked final, we know that no subclass can
120   // override this member function and so we can devirtualize it. For example:
121   //
122   // struct A { virtual void f(); }
123   // struct B final : A { };
124   //
125   // void f(B *b) {
126   //   b->f();
127   // }
128   //
129   const CXXRecordDecl *MostDerivedClassDecl = getMostDerivedClassDecl(Base);
130   if (MostDerivedClassDecl->hasAttr<FinalAttr>())
131     return true;
132 
133   // If the member function is marked 'final', we know that it can't be
134   // overridden and can therefore devirtualize it.
135   if (MD->hasAttr<FinalAttr>())
136     return true;
137 
138   // Similarly, if the class itself is marked 'final' it can't be overridden
139   // and we can therefore devirtualize the member function call.
140   if (MD->getParent()->hasAttr<FinalAttr>())
141     return true;
142 
143   Base = skipNoOpCastsAndParens(Base);
144   if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Base)) {
145     if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl())) {
146       // This is a record decl. We know the type and can devirtualize it.
147       return VD->getType()->isRecordType();
148     }
149 
150     return false;
151   }
152 
153   // We can always devirtualize calls on temporary object expressions.
154   if (isa<CXXConstructExpr>(Base))
155     return true;
156 
157   // And calls on bound temporaries.
158   if (isa<CXXBindTemporaryExpr>(Base))
159     return true;
160 
161   // Check if this is a call expr that returns a record type.
162   if (const CallExpr *CE = dyn_cast<CallExpr>(Base))
163     return CE->getCallReturnType()->isRecordType();
164 
165   // We can't devirtualize the call.
166   return false;
167 }
168 
169 // Note: This function also emit constructor calls to support a MSVC
170 // extensions allowing explicit constructor function call.
171 RValue CodeGenFunction::EmitCXXMemberCallExpr(const CXXMemberCallExpr *CE,
172                                               ReturnValueSlot ReturnValue) {
173   const Expr *callee = CE->getCallee()->IgnoreParens();
174 
175   if (isa<BinaryOperator>(callee))
176     return EmitCXXMemberPointerCallExpr(CE, ReturnValue);
177 
178   const MemberExpr *ME = cast<MemberExpr>(callee);
179   const CXXMethodDecl *MD = cast<CXXMethodDecl>(ME->getMemberDecl());
180 
181   CGDebugInfo *DI = getDebugInfo();
182   if (DI && CGM.getCodeGenOpts().LimitDebugInfo
183       && !isa<CallExpr>(ME->getBase())) {
184     QualType PQTy = ME->getBase()->IgnoreParenImpCasts()->getType();
185     if (const PointerType * PTy = dyn_cast<PointerType>(PQTy)) {
186       DI->getOrCreateRecordType(PTy->getPointeeType(),
187                                 MD->getParent()->getLocation());
188     }
189   }
190 
191   if (MD->isStatic()) {
192     // The method is static, emit it as we would a regular call.
193     llvm::Value *Callee = CGM.GetAddrOfFunction(MD);
194     return EmitCall(getContext().getPointerType(MD->getType()), Callee,
195                     ReturnValue, CE->arg_begin(), CE->arg_end());
196   }
197 
198   // Compute the object pointer.
199   llvm::Value *This;
200   if (ME->isArrow())
201     This = EmitScalarExpr(ME->getBase());
202   else
203     This = EmitLValue(ME->getBase()).getAddress();
204 
205   if (MD->isTrivial()) {
206     if (isa<CXXDestructorDecl>(MD)) return RValue::get(0);
207     if (isa<CXXConstructorDecl>(MD) &&
208         cast<CXXConstructorDecl>(MD)->isDefaultConstructor())
209       return RValue::get(0);
210 
211     if (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator()) {
212       // We don't like to generate the trivial copy/move assignment operator
213       // when it isn't necessary; just produce the proper effect here.
214       llvm::Value *RHS = EmitLValue(*CE->arg_begin()).getAddress();
215       EmitAggregateCopy(This, RHS, CE->getType());
216       return RValue::get(This);
217     }
218 
219     if (isa<CXXConstructorDecl>(MD) &&
220         cast<CXXConstructorDecl>(MD)->isCopyOrMoveConstructor()) {
221       // Trivial move and copy ctor are the same.
222       llvm::Value *RHS = EmitLValue(*CE->arg_begin()).getAddress();
223       EmitSynthesizedCXXCopyCtorCall(cast<CXXConstructorDecl>(MD), This, RHS,
224                                      CE->arg_begin(), CE->arg_end());
225       return RValue::get(This);
226     }
227     llvm_unreachable("unknown trivial member function");
228   }
229 
230   // Compute the function type we're calling.
231   const CGFunctionInfo *FInfo = 0;
232   if (isa<CXXDestructorDecl>(MD))
233     FInfo = &CGM.getTypes().arrangeCXXDestructor(cast<CXXDestructorDecl>(MD),
234                                                  Dtor_Complete);
235   else if (isa<CXXConstructorDecl>(MD))
236     FInfo = &CGM.getTypes().arrangeCXXConstructorDeclaration(
237                                                  cast<CXXConstructorDecl>(MD),
238                                                  Ctor_Complete);
239   else
240     FInfo = &CGM.getTypes().arrangeCXXMethodDeclaration(MD);
241 
242   llvm::Type *Ty = CGM.getTypes().GetFunctionType(*FInfo);
243 
244   // C++ [class.virtual]p12:
245   //   Explicit qualification with the scope operator (5.1) suppresses the
246   //   virtual call mechanism.
247   //
248   // We also don't emit a virtual call if the base expression has a record type
249   // because then we know what the type is.
250   bool UseVirtualCall;
251   UseVirtualCall = MD->isVirtual() && !ME->hasQualifier()
252                    && !canDevirtualizeMemberFunctionCalls(getContext(),
253                                                           ME->getBase(), MD);
254   llvm::Value *Callee;
255   if (const CXXDestructorDecl *Dtor = dyn_cast<CXXDestructorDecl>(MD)) {
256     if (UseVirtualCall) {
257       Callee = BuildVirtualCall(Dtor, Dtor_Complete, This, Ty);
258     } else {
259       if (getContext().getLangOpts().AppleKext &&
260           MD->isVirtual() &&
261           ME->hasQualifier())
262         Callee = BuildAppleKextVirtualCall(MD, ME->getQualifier(), Ty);
263       else
264         Callee = CGM.GetAddrOfFunction(GlobalDecl(Dtor, Dtor_Complete), Ty);
265     }
266   } else if (const CXXConstructorDecl *Ctor =
267                dyn_cast<CXXConstructorDecl>(MD)) {
268     Callee = CGM.GetAddrOfFunction(GlobalDecl(Ctor, Ctor_Complete), Ty);
269   } else if (UseVirtualCall) {
270       Callee = BuildVirtualCall(MD, This, Ty);
271   } else {
272     if (getContext().getLangOpts().AppleKext &&
273         MD->isVirtual() &&
274         ME->hasQualifier())
275       Callee = BuildAppleKextVirtualCall(MD, ME->getQualifier(), Ty);
276     else
277       Callee = CGM.GetAddrOfFunction(MD, Ty);
278   }
279 
280   return EmitCXXMemberCall(MD, Callee, ReturnValue, This, /*VTT=*/0,
281                            CE->arg_begin(), CE->arg_end());
282 }
283 
284 RValue
285 CodeGenFunction::EmitCXXMemberPointerCallExpr(const CXXMemberCallExpr *E,
286                                               ReturnValueSlot ReturnValue) {
287   const BinaryOperator *BO =
288       cast<BinaryOperator>(E->getCallee()->IgnoreParens());
289   const Expr *BaseExpr = BO->getLHS();
290   const Expr *MemFnExpr = BO->getRHS();
291 
292   const MemberPointerType *MPT =
293     MemFnExpr->getType()->castAs<MemberPointerType>();
294 
295   const FunctionProtoType *FPT =
296     MPT->getPointeeType()->castAs<FunctionProtoType>();
297   const CXXRecordDecl *RD =
298     cast<CXXRecordDecl>(MPT->getClass()->getAs<RecordType>()->getDecl());
299 
300   // Get the member function pointer.
301   llvm::Value *MemFnPtr = EmitScalarExpr(MemFnExpr);
302 
303   // Emit the 'this' pointer.
304   llvm::Value *This;
305 
306   if (BO->getOpcode() == BO_PtrMemI)
307     This = EmitScalarExpr(BaseExpr);
308   else
309     This = EmitLValue(BaseExpr).getAddress();
310 
311   // Ask the ABI to load the callee.  Note that This is modified.
312   llvm::Value *Callee =
313     CGM.getCXXABI().EmitLoadOfMemberFunctionPointer(*this, This, MemFnPtr, MPT);
314 
315   CallArgList Args;
316 
317   QualType ThisType =
318     getContext().getPointerType(getContext().getTagDeclType(RD));
319 
320   // Push the this ptr.
321   Args.add(RValue::get(This), ThisType);
322 
323   // And the rest of the call args
324   EmitCallArgs(Args, FPT, E->arg_begin(), E->arg_end());
325   return EmitCall(CGM.getTypes().arrangeFunctionCall(Args, FPT), Callee,
326                   ReturnValue, Args);
327 }
328 
329 RValue
330 CodeGenFunction::EmitCXXOperatorMemberCallExpr(const CXXOperatorCallExpr *E,
331                                                const CXXMethodDecl *MD,
332                                                ReturnValueSlot ReturnValue) {
333   assert(MD->isInstance() &&
334          "Trying to emit a member call expr on a static method!");
335   LValue LV = EmitLValue(E->getArg(0));
336   llvm::Value *This = LV.getAddress();
337 
338   if ((MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator()) &&
339       MD->isTrivial()) {
340     llvm::Value *Src = EmitLValue(E->getArg(1)).getAddress();
341     QualType Ty = E->getType();
342     EmitAggregateCopy(This, Src, Ty);
343     return RValue::get(This);
344   }
345 
346   llvm::Value *Callee = EmitCXXOperatorMemberCallee(E, MD, This);
347   return EmitCXXMemberCall(MD, Callee, ReturnValue, This, /*VTT=*/0,
348                            E->arg_begin() + 1, E->arg_end());
349 }
350 
351 RValue CodeGenFunction::EmitCUDAKernelCallExpr(const CUDAKernelCallExpr *E,
352                                                ReturnValueSlot ReturnValue) {
353   return CGM.getCUDARuntime().EmitCUDAKernelCallExpr(*this, E, ReturnValue);
354 }
355 
356 static void EmitNullBaseClassInitialization(CodeGenFunction &CGF,
357                                             llvm::Value *DestPtr,
358                                             const CXXRecordDecl *Base) {
359   if (Base->isEmpty())
360     return;
361 
362   DestPtr = CGF.EmitCastToVoidPtr(DestPtr);
363 
364   const ASTRecordLayout &Layout = CGF.getContext().getASTRecordLayout(Base);
365   CharUnits Size = Layout.getNonVirtualSize();
366   CharUnits Align = Layout.getNonVirtualAlign();
367 
368   llvm::Value *SizeVal = CGF.CGM.getSize(Size);
369 
370   // If the type contains a pointer to data member we can't memset it to zero.
371   // Instead, create a null constant and copy it to the destination.
372   // TODO: there are other patterns besides zero that we can usefully memset,
373   // like -1, which happens to be the pattern used by member-pointers.
374   // TODO: isZeroInitializable can be over-conservative in the case where a
375   // virtual base contains a member pointer.
376   if (!CGF.CGM.getTypes().isZeroInitializable(Base)) {
377     llvm::Constant *NullConstant = CGF.CGM.EmitNullConstantForBase(Base);
378 
379     llvm::GlobalVariable *NullVariable =
380       new llvm::GlobalVariable(CGF.CGM.getModule(), NullConstant->getType(),
381                                /*isConstant=*/true,
382                                llvm::GlobalVariable::PrivateLinkage,
383                                NullConstant, Twine());
384     NullVariable->setAlignment(Align.getQuantity());
385     llvm::Value *SrcPtr = CGF.EmitCastToVoidPtr(NullVariable);
386 
387     // Get and call the appropriate llvm.memcpy overload.
388     CGF.Builder.CreateMemCpy(DestPtr, SrcPtr, SizeVal, Align.getQuantity());
389     return;
390   }
391 
392   // Otherwise, just memset the whole thing to zero.  This is legal
393   // because in LLVM, all default initializers (other than the ones we just
394   // handled above) are guaranteed to have a bit pattern of all zeros.
395   CGF.Builder.CreateMemSet(DestPtr, CGF.Builder.getInt8(0), SizeVal,
396                            Align.getQuantity());
397 }
398 
399 void
400 CodeGenFunction::EmitCXXConstructExpr(const CXXConstructExpr *E,
401                                       AggValueSlot Dest) {
402   assert(!Dest.isIgnored() && "Must have a destination!");
403   const CXXConstructorDecl *CD = E->getConstructor();
404 
405   // If we require zero initialization before (or instead of) calling the
406   // constructor, as can be the case with a non-user-provided default
407   // constructor, emit the zero initialization now, unless destination is
408   // already zeroed.
409   if (E->requiresZeroInitialization() && !Dest.isZeroed()) {
410     switch (E->getConstructionKind()) {
411     case CXXConstructExpr::CK_Delegating:
412       assert(0 && "Delegating constructor should not need zeroing");
413     case CXXConstructExpr::CK_Complete:
414       EmitNullInitialization(Dest.getAddr(), E->getType());
415       break;
416     case CXXConstructExpr::CK_VirtualBase:
417     case CXXConstructExpr::CK_NonVirtualBase:
418       EmitNullBaseClassInitialization(*this, Dest.getAddr(), CD->getParent());
419       break;
420     }
421   }
422 
423   // If this is a call to a trivial default constructor, do nothing.
424   if (CD->isTrivial() && CD->isDefaultConstructor())
425     return;
426 
427   // Elide the constructor if we're constructing from a temporary.
428   // The temporary check is required because Sema sets this on NRVO
429   // returns.
430   if (getContext().getLangOpts().ElideConstructors && E->isElidable()) {
431     assert(getContext().hasSameUnqualifiedType(E->getType(),
432                                                E->getArg(0)->getType()));
433     if (E->getArg(0)->isTemporaryObject(getContext(), CD->getParent())) {
434       EmitAggExpr(E->getArg(0), Dest);
435       return;
436     }
437   }
438 
439   if (const ConstantArrayType *arrayType
440         = getContext().getAsConstantArrayType(E->getType())) {
441     EmitCXXAggrConstructorCall(CD, arrayType, Dest.getAddr(),
442                                E->arg_begin(), E->arg_end());
443   } else {
444     CXXCtorType Type = Ctor_Complete;
445     bool ForVirtualBase = false;
446 
447     switch (E->getConstructionKind()) {
448      case CXXConstructExpr::CK_Delegating:
449       // We should be emitting a constructor; GlobalDecl will assert this
450       Type = CurGD.getCtorType();
451       break;
452 
453      case CXXConstructExpr::CK_Complete:
454       Type = Ctor_Complete;
455       break;
456 
457      case CXXConstructExpr::CK_VirtualBase:
458       ForVirtualBase = true;
459       // fall-through
460 
461      case CXXConstructExpr::CK_NonVirtualBase:
462       Type = Ctor_Base;
463     }
464 
465     // Call the constructor.
466     EmitCXXConstructorCall(CD, Type, ForVirtualBase, Dest.getAddr(),
467                            E->arg_begin(), E->arg_end());
468   }
469 }
470 
471 void
472 CodeGenFunction::EmitSynthesizedCXXCopyCtor(llvm::Value *Dest,
473                                             llvm::Value *Src,
474                                             const Expr *Exp) {
475   if (const ExprWithCleanups *E = dyn_cast<ExprWithCleanups>(Exp))
476     Exp = E->getSubExpr();
477   assert(isa<CXXConstructExpr>(Exp) &&
478          "EmitSynthesizedCXXCopyCtor - unknown copy ctor expr");
479   const CXXConstructExpr* E = cast<CXXConstructExpr>(Exp);
480   const CXXConstructorDecl *CD = E->getConstructor();
481   RunCleanupsScope Scope(*this);
482 
483   // If we require zero initialization before (or instead of) calling the
484   // constructor, as can be the case with a non-user-provided default
485   // constructor, emit the zero initialization now.
486   // FIXME. Do I still need this for a copy ctor synthesis?
487   if (E->requiresZeroInitialization())
488     EmitNullInitialization(Dest, E->getType());
489 
490   assert(!getContext().getAsConstantArrayType(E->getType())
491          && "EmitSynthesizedCXXCopyCtor - Copied-in Array");
492   EmitSynthesizedCXXCopyCtorCall(CD, Dest, Src,
493                                  E->arg_begin(), E->arg_end());
494 }
495 
496 static CharUnits CalculateCookiePadding(CodeGenFunction &CGF,
497                                         const CXXNewExpr *E) {
498   if (!E->isArray())
499     return CharUnits::Zero();
500 
501   // No cookie is required if the operator new[] being used is the
502   // reserved placement operator new[].
503   if (E->getOperatorNew()->isReservedGlobalPlacementOperator())
504     return CharUnits::Zero();
505 
506   return CGF.CGM.getCXXABI().GetArrayCookieSize(E);
507 }
508 
509 static llvm::Value *EmitCXXNewAllocSize(CodeGenFunction &CGF,
510                                         const CXXNewExpr *e,
511                                         unsigned minElements,
512                                         llvm::Value *&numElements,
513                                         llvm::Value *&sizeWithoutCookie) {
514   QualType type = e->getAllocatedType();
515 
516   if (!e->isArray()) {
517     CharUnits typeSize = CGF.getContext().getTypeSizeInChars(type);
518     sizeWithoutCookie
519       = llvm::ConstantInt::get(CGF.SizeTy, typeSize.getQuantity());
520     return sizeWithoutCookie;
521   }
522 
523   // The width of size_t.
524   unsigned sizeWidth = CGF.SizeTy->getBitWidth();
525 
526   // Figure out the cookie size.
527   llvm::APInt cookieSize(sizeWidth,
528                          CalculateCookiePadding(CGF, e).getQuantity());
529 
530   // Emit the array size expression.
531   // We multiply the size of all dimensions for NumElements.
532   // e.g for 'int[2][3]', ElemType is 'int' and NumElements is 6.
533   numElements = CGF.EmitScalarExpr(e->getArraySize());
534   assert(isa<llvm::IntegerType>(numElements->getType()));
535 
536   // The number of elements can be have an arbitrary integer type;
537   // essentially, we need to multiply it by a constant factor, add a
538   // cookie size, and verify that the result is representable as a
539   // size_t.  That's just a gloss, though, and it's wrong in one
540   // important way: if the count is negative, it's an error even if
541   // the cookie size would bring the total size >= 0.
542   bool isSigned
543     = e->getArraySize()->getType()->isSignedIntegerOrEnumerationType();
544   llvm::IntegerType *numElementsType
545     = cast<llvm::IntegerType>(numElements->getType());
546   unsigned numElementsWidth = numElementsType->getBitWidth();
547 
548   // Compute the constant factor.
549   llvm::APInt arraySizeMultiplier(sizeWidth, 1);
550   while (const ConstantArrayType *CAT
551              = CGF.getContext().getAsConstantArrayType(type)) {
552     type = CAT->getElementType();
553     arraySizeMultiplier *= CAT->getSize();
554   }
555 
556   CharUnits typeSize = CGF.getContext().getTypeSizeInChars(type);
557   llvm::APInt typeSizeMultiplier(sizeWidth, typeSize.getQuantity());
558   typeSizeMultiplier *= arraySizeMultiplier;
559 
560   // This will be a size_t.
561   llvm::Value *size;
562 
563   // If someone is doing 'new int[42]' there is no need to do a dynamic check.
564   // Don't bloat the -O0 code.
565   if (llvm::ConstantInt *numElementsC =
566         dyn_cast<llvm::ConstantInt>(numElements)) {
567     const llvm::APInt &count = numElementsC->getValue();
568 
569     bool hasAnyOverflow = false;
570 
571     // If 'count' was a negative number, it's an overflow.
572     if (isSigned && count.isNegative())
573       hasAnyOverflow = true;
574 
575     // We want to do all this arithmetic in size_t.  If numElements is
576     // wider than that, check whether it's already too big, and if so,
577     // overflow.
578     else if (numElementsWidth > sizeWidth &&
579              numElementsWidth - sizeWidth > count.countLeadingZeros())
580       hasAnyOverflow = true;
581 
582     // Okay, compute a count at the right width.
583     llvm::APInt adjustedCount = count.zextOrTrunc(sizeWidth);
584 
585     // If there is a brace-initializer, we cannot allocate fewer elements than
586     // there are initializers. If we do, that's treated like an overflow.
587     if (adjustedCount.ult(minElements))
588       hasAnyOverflow = true;
589 
590     // Scale numElements by that.  This might overflow, but we don't
591     // care because it only overflows if allocationSize does, too, and
592     // if that overflows then we shouldn't use this.
593     numElements = llvm::ConstantInt::get(CGF.SizeTy,
594                                          adjustedCount * arraySizeMultiplier);
595 
596     // Compute the size before cookie, and track whether it overflowed.
597     bool overflow;
598     llvm::APInt allocationSize
599       = adjustedCount.umul_ov(typeSizeMultiplier, overflow);
600     hasAnyOverflow |= overflow;
601 
602     // Add in the cookie, and check whether it's overflowed.
603     if (cookieSize != 0) {
604       // Save the current size without a cookie.  This shouldn't be
605       // used if there was overflow.
606       sizeWithoutCookie = llvm::ConstantInt::get(CGF.SizeTy, allocationSize);
607 
608       allocationSize = allocationSize.uadd_ov(cookieSize, overflow);
609       hasAnyOverflow |= overflow;
610     }
611 
612     // On overflow, produce a -1 so operator new will fail.
613     if (hasAnyOverflow) {
614       size = llvm::Constant::getAllOnesValue(CGF.SizeTy);
615     } else {
616       size = llvm::ConstantInt::get(CGF.SizeTy, allocationSize);
617     }
618 
619   // Otherwise, we might need to use the overflow intrinsics.
620   } else {
621     // There are up to five conditions we need to test for:
622     // 1) if isSigned, we need to check whether numElements is negative;
623     // 2) if numElementsWidth > sizeWidth, we need to check whether
624     //   numElements is larger than something representable in size_t;
625     // 3) if minElements > 0, we need to check whether numElements is smaller
626     //    than that.
627     // 4) we need to compute
628     //      sizeWithoutCookie := numElements * typeSizeMultiplier
629     //    and check whether it overflows; and
630     // 5) if we need a cookie, we need to compute
631     //      size := sizeWithoutCookie + cookieSize
632     //    and check whether it overflows.
633 
634     llvm::Value *hasOverflow = 0;
635 
636     // If numElementsWidth > sizeWidth, then one way or another, we're
637     // going to have to do a comparison for (2), and this happens to
638     // take care of (1), too.
639     if (numElementsWidth > sizeWidth) {
640       llvm::APInt threshold(numElementsWidth, 1);
641       threshold <<= sizeWidth;
642 
643       llvm::Value *thresholdV
644         = llvm::ConstantInt::get(numElementsType, threshold);
645 
646       hasOverflow = CGF.Builder.CreateICmpUGE(numElements, thresholdV);
647       numElements = CGF.Builder.CreateTrunc(numElements, CGF.SizeTy);
648 
649     // Otherwise, if we're signed, we want to sext up to size_t.
650     } else if (isSigned) {
651       if (numElementsWidth < sizeWidth)
652         numElements = CGF.Builder.CreateSExt(numElements, CGF.SizeTy);
653 
654       // If there's a non-1 type size multiplier, then we can do the
655       // signedness check at the same time as we do the multiply
656       // because a negative number times anything will cause an
657       // unsigned overflow.  Otherwise, we have to do it here. But at least
658       // in this case, we can subsume the >= minElements check.
659       if (typeSizeMultiplier == 1)
660         hasOverflow = CGF.Builder.CreateICmpSLT(numElements,
661                               llvm::ConstantInt::get(CGF.SizeTy, minElements));
662 
663     // Otherwise, zext up to size_t if necessary.
664     } else if (numElementsWidth < sizeWidth) {
665       numElements = CGF.Builder.CreateZExt(numElements, CGF.SizeTy);
666     }
667 
668     assert(numElements->getType() == CGF.SizeTy);
669 
670     if (minElements) {
671       // Don't allow allocation of fewer elements than we have initializers.
672       if (!hasOverflow) {
673         hasOverflow = CGF.Builder.CreateICmpULT(numElements,
674                               llvm::ConstantInt::get(CGF.SizeTy, minElements));
675       } else if (numElementsWidth > sizeWidth) {
676         // The other existing overflow subsumes this check.
677         // We do an unsigned comparison, since any signed value < -1 is
678         // taken care of either above or below.
679         hasOverflow = CGF.Builder.CreateOr(hasOverflow,
680                           CGF.Builder.CreateICmpULT(numElements,
681                               llvm::ConstantInt::get(CGF.SizeTy, minElements)));
682       }
683     }
684 
685     size = numElements;
686 
687     // Multiply by the type size if necessary.  This multiplier
688     // includes all the factors for nested arrays.
689     //
690     // This step also causes numElements to be scaled up by the
691     // nested-array factor if necessary.  Overflow on this computation
692     // can be ignored because the result shouldn't be used if
693     // allocation fails.
694     if (typeSizeMultiplier != 1) {
695       llvm::Value *umul_with_overflow
696         = CGF.CGM.getIntrinsic(llvm::Intrinsic::umul_with_overflow, CGF.SizeTy);
697 
698       llvm::Value *tsmV =
699         llvm::ConstantInt::get(CGF.SizeTy, typeSizeMultiplier);
700       llvm::Value *result =
701         CGF.Builder.CreateCall2(umul_with_overflow, size, tsmV);
702 
703       llvm::Value *overflowed = CGF.Builder.CreateExtractValue(result, 1);
704       if (hasOverflow)
705         hasOverflow = CGF.Builder.CreateOr(hasOverflow, overflowed);
706       else
707         hasOverflow = overflowed;
708 
709       size = CGF.Builder.CreateExtractValue(result, 0);
710 
711       // Also scale up numElements by the array size multiplier.
712       if (arraySizeMultiplier != 1) {
713         // If the base element type size is 1, then we can re-use the
714         // multiply we just did.
715         if (typeSize.isOne()) {
716           assert(arraySizeMultiplier == typeSizeMultiplier);
717           numElements = size;
718 
719         // Otherwise we need a separate multiply.
720         } else {
721           llvm::Value *asmV =
722             llvm::ConstantInt::get(CGF.SizeTy, arraySizeMultiplier);
723           numElements = CGF.Builder.CreateMul(numElements, asmV);
724         }
725       }
726     } else {
727       // numElements doesn't need to be scaled.
728       assert(arraySizeMultiplier == 1);
729     }
730 
731     // Add in the cookie size if necessary.
732     if (cookieSize != 0) {
733       sizeWithoutCookie = size;
734 
735       llvm::Value *uadd_with_overflow
736         = CGF.CGM.getIntrinsic(llvm::Intrinsic::uadd_with_overflow, CGF.SizeTy);
737 
738       llvm::Value *cookieSizeV = llvm::ConstantInt::get(CGF.SizeTy, cookieSize);
739       llvm::Value *result =
740         CGF.Builder.CreateCall2(uadd_with_overflow, size, cookieSizeV);
741 
742       llvm::Value *overflowed = CGF.Builder.CreateExtractValue(result, 1);
743       if (hasOverflow)
744         hasOverflow = CGF.Builder.CreateOr(hasOverflow, overflowed);
745       else
746         hasOverflow = overflowed;
747 
748       size = CGF.Builder.CreateExtractValue(result, 0);
749     }
750 
751     // If we had any possibility of dynamic overflow, make a select to
752     // overwrite 'size' with an all-ones value, which should cause
753     // operator new to throw.
754     if (hasOverflow)
755       size = CGF.Builder.CreateSelect(hasOverflow,
756                                  llvm::Constant::getAllOnesValue(CGF.SizeTy),
757                                       size);
758   }
759 
760   if (cookieSize == 0)
761     sizeWithoutCookie = size;
762   else
763     assert(sizeWithoutCookie && "didn't set sizeWithoutCookie?");
764 
765   return size;
766 }
767 
768 static void StoreAnyExprIntoOneUnit(CodeGenFunction &CGF, const Expr *Init,
769                                     QualType AllocType, llvm::Value *NewPtr) {
770 
771   CharUnits Alignment = CGF.getContext().getTypeAlignInChars(AllocType);
772   if (!CGF.hasAggregateLLVMType(AllocType))
773     CGF.EmitScalarInit(Init, 0, CGF.MakeAddrLValue(NewPtr, AllocType,
774                                                    Alignment),
775                        false);
776   else if (AllocType->isAnyComplexType())
777     CGF.EmitComplexExprIntoAddr(Init, NewPtr,
778                                 AllocType.isVolatileQualified());
779   else {
780     AggValueSlot Slot
781       = AggValueSlot::forAddr(NewPtr, Alignment, AllocType.getQualifiers(),
782                               AggValueSlot::IsDestructed,
783                               AggValueSlot::DoesNotNeedGCBarriers,
784                               AggValueSlot::IsNotAliased,
785                               AggValueSlot::IsCompleteObject);
786     CGF.EmitAggExpr(Init, Slot);
787 
788     CGF.MaybeEmitStdInitializerListCleanup(NewPtr, Init);
789   }
790 }
791 
792 void
793 CodeGenFunction::EmitNewArrayInitializer(const CXXNewExpr *E,
794                                          QualType elementType,
795                                          llvm::Value *beginPtr,
796                                          llvm::Value *numElements) {
797   if (!E->hasInitializer())
798     return; // We have a POD type.
799 
800   llvm::Value *explicitPtr = beginPtr;
801   // Find the end of the array, hoisted out of the loop.
802   llvm::Value *endPtr =
803     Builder.CreateInBoundsGEP(beginPtr, numElements, "array.end");
804 
805   unsigned initializerElements = 0;
806 
807   const Expr *Init = E->getInitializer();
808   llvm::AllocaInst *endOfInit = 0;
809   QualType::DestructionKind dtorKind = elementType.isDestructedType();
810   EHScopeStack::stable_iterator cleanup;
811   llvm::Instruction *cleanupDominator = 0;
812   // If the initializer is an initializer list, first do the explicit elements.
813   if (const InitListExpr *ILE = dyn_cast<InitListExpr>(Init)) {
814     initializerElements = ILE->getNumInits();
815 
816     // Enter a partial-destruction cleanup if necessary.
817     if (needsEHCleanup(dtorKind)) {
818       // In principle we could tell the cleanup where we are more
819       // directly, but the control flow can get so varied here that it
820       // would actually be quite complex.  Therefore we go through an
821       // alloca.
822       endOfInit = CreateTempAlloca(beginPtr->getType(), "array.endOfInit");
823       cleanupDominator = Builder.CreateStore(beginPtr, endOfInit);
824       pushIrregularPartialArrayCleanup(beginPtr, endOfInit, elementType,
825                                        getDestroyer(dtorKind));
826       cleanup = EHStack.stable_begin();
827     }
828 
829     for (unsigned i = 0, e = ILE->getNumInits(); i != e; ++i) {
830       // Tell the cleanup that it needs to destroy up to this
831       // element.  TODO: some of these stores can be trivially
832       // observed to be unnecessary.
833       if (endOfInit) Builder.CreateStore(explicitPtr, endOfInit);
834       StoreAnyExprIntoOneUnit(*this, ILE->getInit(i), elementType, explicitPtr);
835       explicitPtr =Builder.CreateConstGEP1_32(explicitPtr, 1, "array.exp.next");
836     }
837 
838     // The remaining elements are filled with the array filler expression.
839     Init = ILE->getArrayFiller();
840   }
841 
842   // Create the continuation block.
843   llvm::BasicBlock *contBB = createBasicBlock("new.loop.end");
844 
845   // If the number of elements isn't constant, we have to now check if there is
846   // anything left to initialize.
847   if (llvm::ConstantInt *constNum = dyn_cast<llvm::ConstantInt>(numElements)) {
848     // If all elements have already been initialized, skip the whole loop.
849     if (constNum->getZExtValue() <= initializerElements) {
850       // If there was a cleanup, deactivate it.
851       if (cleanupDominator)
852         DeactivateCleanupBlock(cleanup, cleanupDominator);;
853       return;
854     }
855   } else {
856     llvm::BasicBlock *nonEmptyBB = createBasicBlock("new.loop.nonempty");
857     llvm::Value *isEmpty = Builder.CreateICmpEQ(explicitPtr, endPtr,
858                                                 "array.isempty");
859     Builder.CreateCondBr(isEmpty, contBB, nonEmptyBB);
860     EmitBlock(nonEmptyBB);
861   }
862 
863   // Enter the loop.
864   llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
865   llvm::BasicBlock *loopBB = createBasicBlock("new.loop");
866 
867   EmitBlock(loopBB);
868 
869   // Set up the current-element phi.
870   llvm::PHINode *curPtr =
871     Builder.CreatePHI(explicitPtr->getType(), 2, "array.cur");
872   curPtr->addIncoming(explicitPtr, entryBB);
873 
874   // Store the new cleanup position for irregular cleanups.
875   if (endOfInit) Builder.CreateStore(curPtr, endOfInit);
876 
877   // Enter a partial-destruction cleanup if necessary.
878   if (!cleanupDominator && needsEHCleanup(dtorKind)) {
879     pushRegularPartialArrayCleanup(beginPtr, curPtr, elementType,
880                                    getDestroyer(dtorKind));
881     cleanup = EHStack.stable_begin();
882     cleanupDominator = Builder.CreateUnreachable();
883   }
884 
885   // Emit the initializer into this element.
886   StoreAnyExprIntoOneUnit(*this, Init, E->getAllocatedType(), curPtr);
887 
888   // Leave the cleanup if we entered one.
889   if (cleanupDominator) {
890     DeactivateCleanupBlock(cleanup, cleanupDominator);
891     cleanupDominator->eraseFromParent();
892   }
893 
894   // Advance to the next element.
895   llvm::Value *nextPtr = Builder.CreateConstGEP1_32(curPtr, 1, "array.next");
896 
897   // Check whether we've gotten to the end of the array and, if so,
898   // exit the loop.
899   llvm::Value *isEnd = Builder.CreateICmpEQ(nextPtr, endPtr, "array.atend");
900   Builder.CreateCondBr(isEnd, contBB, loopBB);
901   curPtr->addIncoming(nextPtr, Builder.GetInsertBlock());
902 
903   EmitBlock(contBB);
904 }
905 
906 static void EmitZeroMemSet(CodeGenFunction &CGF, QualType T,
907                            llvm::Value *NewPtr, llvm::Value *Size) {
908   CGF.EmitCastToVoidPtr(NewPtr);
909   CharUnits Alignment = CGF.getContext().getTypeAlignInChars(T);
910   CGF.Builder.CreateMemSet(NewPtr, CGF.Builder.getInt8(0), Size,
911                            Alignment.getQuantity(), false);
912 }
913 
914 static void EmitNewInitializer(CodeGenFunction &CGF, const CXXNewExpr *E,
915                                QualType ElementType,
916                                llvm::Value *NewPtr,
917                                llvm::Value *NumElements,
918                                llvm::Value *AllocSizeWithoutCookie) {
919   const Expr *Init = E->getInitializer();
920   if (E->isArray()) {
921     if (const CXXConstructExpr *CCE = dyn_cast_or_null<CXXConstructExpr>(Init)){
922       CXXConstructorDecl *Ctor = CCE->getConstructor();
923       bool RequiresZeroInitialization = false;
924       if (Ctor->isTrivial()) {
925         // If new expression did not specify value-initialization, then there
926         // is no initialization.
927         if (!CCE->requiresZeroInitialization() || Ctor->getParent()->isEmpty())
928           return;
929 
930         if (CGF.CGM.getTypes().isZeroInitializable(ElementType)) {
931           // Optimization: since zero initialization will just set the memory
932           // to all zeroes, generate a single memset to do it in one shot.
933           EmitZeroMemSet(CGF, ElementType, NewPtr, AllocSizeWithoutCookie);
934           return;
935         }
936 
937         RequiresZeroInitialization = true;
938       }
939 
940       CGF.EmitCXXAggrConstructorCall(Ctor, NumElements, NewPtr,
941                                      CCE->arg_begin(),  CCE->arg_end(),
942                                      RequiresZeroInitialization);
943       return;
944     } else if (Init && isa<ImplicitValueInitExpr>(Init) &&
945                CGF.CGM.getTypes().isZeroInitializable(ElementType)) {
946       // Optimization: since zero initialization will just set the memory
947       // to all zeroes, generate a single memset to do it in one shot.
948       EmitZeroMemSet(CGF, ElementType, NewPtr, AllocSizeWithoutCookie);
949       return;
950     }
951     CGF.EmitNewArrayInitializer(E, ElementType, NewPtr, NumElements);
952     return;
953   }
954 
955   if (!Init)
956     return;
957 
958   StoreAnyExprIntoOneUnit(CGF, Init, E->getAllocatedType(), NewPtr);
959 }
960 
961 namespace {
962   /// A cleanup to call the given 'operator delete' function upon
963   /// abnormal exit from a new expression.
964   class CallDeleteDuringNew : public EHScopeStack::Cleanup {
965     size_t NumPlacementArgs;
966     const FunctionDecl *OperatorDelete;
967     llvm::Value *Ptr;
968     llvm::Value *AllocSize;
969 
970     RValue *getPlacementArgs() { return reinterpret_cast<RValue*>(this+1); }
971 
972   public:
973     static size_t getExtraSize(size_t NumPlacementArgs) {
974       return NumPlacementArgs * sizeof(RValue);
975     }
976 
977     CallDeleteDuringNew(size_t NumPlacementArgs,
978                         const FunctionDecl *OperatorDelete,
979                         llvm::Value *Ptr,
980                         llvm::Value *AllocSize)
981       : NumPlacementArgs(NumPlacementArgs), OperatorDelete(OperatorDelete),
982         Ptr(Ptr), AllocSize(AllocSize) {}
983 
984     void setPlacementArg(unsigned I, RValue Arg) {
985       assert(I < NumPlacementArgs && "index out of range");
986       getPlacementArgs()[I] = Arg;
987     }
988 
989     void Emit(CodeGenFunction &CGF, Flags flags) {
990       const FunctionProtoType *FPT
991         = OperatorDelete->getType()->getAs<FunctionProtoType>();
992       assert(FPT->getNumArgs() == NumPlacementArgs + 1 ||
993              (FPT->getNumArgs() == 2 && NumPlacementArgs == 0));
994 
995       CallArgList DeleteArgs;
996 
997       // The first argument is always a void*.
998       FunctionProtoType::arg_type_iterator AI = FPT->arg_type_begin();
999       DeleteArgs.add(RValue::get(Ptr), *AI++);
1000 
1001       // A member 'operator delete' can take an extra 'size_t' argument.
1002       if (FPT->getNumArgs() == NumPlacementArgs + 2)
1003         DeleteArgs.add(RValue::get(AllocSize), *AI++);
1004 
1005       // Pass the rest of the arguments, which must match exactly.
1006       for (unsigned I = 0; I != NumPlacementArgs; ++I)
1007         DeleteArgs.add(getPlacementArgs()[I], *AI++);
1008 
1009       // Call 'operator delete'.
1010       CGF.EmitCall(CGF.CGM.getTypes().arrangeFunctionCall(DeleteArgs, FPT),
1011                    CGF.CGM.GetAddrOfFunction(OperatorDelete),
1012                    ReturnValueSlot(), DeleteArgs, OperatorDelete);
1013     }
1014   };
1015 
1016   /// A cleanup to call the given 'operator delete' function upon
1017   /// abnormal exit from a new expression when the new expression is
1018   /// conditional.
1019   class CallDeleteDuringConditionalNew : public EHScopeStack::Cleanup {
1020     size_t NumPlacementArgs;
1021     const FunctionDecl *OperatorDelete;
1022     DominatingValue<RValue>::saved_type Ptr;
1023     DominatingValue<RValue>::saved_type AllocSize;
1024 
1025     DominatingValue<RValue>::saved_type *getPlacementArgs() {
1026       return reinterpret_cast<DominatingValue<RValue>::saved_type*>(this+1);
1027     }
1028 
1029   public:
1030     static size_t getExtraSize(size_t NumPlacementArgs) {
1031       return NumPlacementArgs * sizeof(DominatingValue<RValue>::saved_type);
1032     }
1033 
1034     CallDeleteDuringConditionalNew(size_t NumPlacementArgs,
1035                                    const FunctionDecl *OperatorDelete,
1036                                    DominatingValue<RValue>::saved_type Ptr,
1037                               DominatingValue<RValue>::saved_type AllocSize)
1038       : NumPlacementArgs(NumPlacementArgs), OperatorDelete(OperatorDelete),
1039         Ptr(Ptr), AllocSize(AllocSize) {}
1040 
1041     void setPlacementArg(unsigned I, DominatingValue<RValue>::saved_type Arg) {
1042       assert(I < NumPlacementArgs && "index out of range");
1043       getPlacementArgs()[I] = Arg;
1044     }
1045 
1046     void Emit(CodeGenFunction &CGF, Flags flags) {
1047       const FunctionProtoType *FPT
1048         = OperatorDelete->getType()->getAs<FunctionProtoType>();
1049       assert(FPT->getNumArgs() == NumPlacementArgs + 1 ||
1050              (FPT->getNumArgs() == 2 && NumPlacementArgs == 0));
1051 
1052       CallArgList DeleteArgs;
1053 
1054       // The first argument is always a void*.
1055       FunctionProtoType::arg_type_iterator AI = FPT->arg_type_begin();
1056       DeleteArgs.add(Ptr.restore(CGF), *AI++);
1057 
1058       // A member 'operator delete' can take an extra 'size_t' argument.
1059       if (FPT->getNumArgs() == NumPlacementArgs + 2) {
1060         RValue RV = AllocSize.restore(CGF);
1061         DeleteArgs.add(RV, *AI++);
1062       }
1063 
1064       // Pass the rest of the arguments, which must match exactly.
1065       for (unsigned I = 0; I != NumPlacementArgs; ++I) {
1066         RValue RV = getPlacementArgs()[I].restore(CGF);
1067         DeleteArgs.add(RV, *AI++);
1068       }
1069 
1070       // Call 'operator delete'.
1071       CGF.EmitCall(CGF.CGM.getTypes().arrangeFunctionCall(DeleteArgs, FPT),
1072                    CGF.CGM.GetAddrOfFunction(OperatorDelete),
1073                    ReturnValueSlot(), DeleteArgs, OperatorDelete);
1074     }
1075   };
1076 }
1077 
1078 /// Enter a cleanup to call 'operator delete' if the initializer in a
1079 /// new-expression throws.
1080 static void EnterNewDeleteCleanup(CodeGenFunction &CGF,
1081                                   const CXXNewExpr *E,
1082                                   llvm::Value *NewPtr,
1083                                   llvm::Value *AllocSize,
1084                                   const CallArgList &NewArgs) {
1085   // If we're not inside a conditional branch, then the cleanup will
1086   // dominate and we can do the easier (and more efficient) thing.
1087   if (!CGF.isInConditionalBranch()) {
1088     CallDeleteDuringNew *Cleanup = CGF.EHStack
1089       .pushCleanupWithExtra<CallDeleteDuringNew>(EHCleanup,
1090                                                  E->getNumPlacementArgs(),
1091                                                  E->getOperatorDelete(),
1092                                                  NewPtr, AllocSize);
1093     for (unsigned I = 0, N = E->getNumPlacementArgs(); I != N; ++I)
1094       Cleanup->setPlacementArg(I, NewArgs[I+1].RV);
1095 
1096     return;
1097   }
1098 
1099   // Otherwise, we need to save all this stuff.
1100   DominatingValue<RValue>::saved_type SavedNewPtr =
1101     DominatingValue<RValue>::save(CGF, RValue::get(NewPtr));
1102   DominatingValue<RValue>::saved_type SavedAllocSize =
1103     DominatingValue<RValue>::save(CGF, RValue::get(AllocSize));
1104 
1105   CallDeleteDuringConditionalNew *Cleanup = CGF.EHStack
1106     .pushCleanupWithExtra<CallDeleteDuringConditionalNew>(EHCleanup,
1107                                                  E->getNumPlacementArgs(),
1108                                                  E->getOperatorDelete(),
1109                                                  SavedNewPtr,
1110                                                  SavedAllocSize);
1111   for (unsigned I = 0, N = E->getNumPlacementArgs(); I != N; ++I)
1112     Cleanup->setPlacementArg(I,
1113                      DominatingValue<RValue>::save(CGF, NewArgs[I+1].RV));
1114 
1115   CGF.initFullExprCleanup();
1116 }
1117 
1118 llvm::Value *CodeGenFunction::EmitCXXNewExpr(const CXXNewExpr *E) {
1119   // The element type being allocated.
1120   QualType allocType = getContext().getBaseElementType(E->getAllocatedType());
1121 
1122   // 1. Build a call to the allocation function.
1123   FunctionDecl *allocator = E->getOperatorNew();
1124   const FunctionProtoType *allocatorType =
1125     allocator->getType()->castAs<FunctionProtoType>();
1126 
1127   CallArgList allocatorArgs;
1128 
1129   // The allocation size is the first argument.
1130   QualType sizeType = getContext().getSizeType();
1131 
1132   // If there is a brace-initializer, cannot allocate fewer elements than inits.
1133   unsigned minElements = 0;
1134   if (E->isArray() && E->hasInitializer()) {
1135     if (const InitListExpr *ILE = dyn_cast<InitListExpr>(E->getInitializer()))
1136       minElements = ILE->getNumInits();
1137   }
1138 
1139   llvm::Value *numElements = 0;
1140   llvm::Value *allocSizeWithoutCookie = 0;
1141   llvm::Value *allocSize =
1142     EmitCXXNewAllocSize(*this, E, minElements, numElements,
1143                         allocSizeWithoutCookie);
1144 
1145   allocatorArgs.add(RValue::get(allocSize), sizeType);
1146 
1147   // Emit the rest of the arguments.
1148   // FIXME: Ideally, this should just use EmitCallArgs.
1149   CXXNewExpr::const_arg_iterator placementArg = E->placement_arg_begin();
1150 
1151   // First, use the types from the function type.
1152   // We start at 1 here because the first argument (the allocation size)
1153   // has already been emitted.
1154   for (unsigned i = 1, e = allocatorType->getNumArgs(); i != e;
1155        ++i, ++placementArg) {
1156     QualType argType = allocatorType->getArgType(i);
1157 
1158     assert(getContext().hasSameUnqualifiedType(argType.getNonReferenceType(),
1159                                                placementArg->getType()) &&
1160            "type mismatch in call argument!");
1161 
1162     EmitCallArg(allocatorArgs, *placementArg, argType);
1163   }
1164 
1165   // Either we've emitted all the call args, or we have a call to a
1166   // variadic function.
1167   assert((placementArg == E->placement_arg_end() ||
1168           allocatorType->isVariadic()) &&
1169          "Extra arguments to non-variadic function!");
1170 
1171   // If we still have any arguments, emit them using the type of the argument.
1172   for (CXXNewExpr::const_arg_iterator placementArgsEnd = E->placement_arg_end();
1173        placementArg != placementArgsEnd; ++placementArg) {
1174     EmitCallArg(allocatorArgs, *placementArg, placementArg->getType());
1175   }
1176 
1177   // Emit the allocation call.  If the allocator is a global placement
1178   // operator, just "inline" it directly.
1179   RValue RV;
1180   if (allocator->isReservedGlobalPlacementOperator()) {
1181     assert(allocatorArgs.size() == 2);
1182     RV = allocatorArgs[1].RV;
1183     // TODO: kill any unnecessary computations done for the size
1184     // argument.
1185   } else {
1186     RV = EmitCall(CGM.getTypes().arrangeFunctionCall(allocatorArgs,
1187                                                      allocatorType),
1188                   CGM.GetAddrOfFunction(allocator), ReturnValueSlot(),
1189                   allocatorArgs, allocator);
1190   }
1191 
1192   // Emit a null check on the allocation result if the allocation
1193   // function is allowed to return null (because it has a non-throwing
1194   // exception spec; for this part, we inline
1195   // CXXNewExpr::shouldNullCheckAllocation()) and we have an
1196   // interesting initializer.
1197   bool nullCheck = allocatorType->isNothrow(getContext()) &&
1198     (!allocType.isPODType(getContext()) || E->hasInitializer());
1199 
1200   llvm::BasicBlock *nullCheckBB = 0;
1201   llvm::BasicBlock *contBB = 0;
1202 
1203   llvm::Value *allocation = RV.getScalarVal();
1204   unsigned AS =
1205     cast<llvm::PointerType>(allocation->getType())->getAddressSpace();
1206 
1207   // The null-check means that the initializer is conditionally
1208   // evaluated.
1209   ConditionalEvaluation conditional(*this);
1210 
1211   if (nullCheck) {
1212     conditional.begin(*this);
1213 
1214     nullCheckBB = Builder.GetInsertBlock();
1215     llvm::BasicBlock *notNullBB = createBasicBlock("new.notnull");
1216     contBB = createBasicBlock("new.cont");
1217 
1218     llvm::Value *isNull = Builder.CreateIsNull(allocation, "new.isnull");
1219     Builder.CreateCondBr(isNull, contBB, notNullBB);
1220     EmitBlock(notNullBB);
1221   }
1222 
1223   // If there's an operator delete, enter a cleanup to call it if an
1224   // exception is thrown.
1225   EHScopeStack::stable_iterator operatorDeleteCleanup;
1226   llvm::Instruction *cleanupDominator = 0;
1227   if (E->getOperatorDelete() &&
1228       !E->getOperatorDelete()->isReservedGlobalPlacementOperator()) {
1229     EnterNewDeleteCleanup(*this, E, allocation, allocSize, allocatorArgs);
1230     operatorDeleteCleanup = EHStack.stable_begin();
1231     cleanupDominator = Builder.CreateUnreachable();
1232   }
1233 
1234   assert((allocSize == allocSizeWithoutCookie) ==
1235          CalculateCookiePadding(*this, E).isZero());
1236   if (allocSize != allocSizeWithoutCookie) {
1237     assert(E->isArray());
1238     allocation = CGM.getCXXABI().InitializeArrayCookie(*this, allocation,
1239                                                        numElements,
1240                                                        E, allocType);
1241   }
1242 
1243   llvm::Type *elementPtrTy
1244     = ConvertTypeForMem(allocType)->getPointerTo(AS);
1245   llvm::Value *result = Builder.CreateBitCast(allocation, elementPtrTy);
1246 
1247   EmitNewInitializer(*this, E, allocType, result, numElements,
1248                      allocSizeWithoutCookie);
1249   if (E->isArray()) {
1250     // NewPtr is a pointer to the base element type.  If we're
1251     // allocating an array of arrays, we'll need to cast back to the
1252     // array pointer type.
1253     llvm::Type *resultType = ConvertTypeForMem(E->getType());
1254     if (result->getType() != resultType)
1255       result = Builder.CreateBitCast(result, resultType);
1256   }
1257 
1258   // Deactivate the 'operator delete' cleanup if we finished
1259   // initialization.
1260   if (operatorDeleteCleanup.isValid()) {
1261     DeactivateCleanupBlock(operatorDeleteCleanup, cleanupDominator);
1262     cleanupDominator->eraseFromParent();
1263   }
1264 
1265   if (nullCheck) {
1266     conditional.end(*this);
1267 
1268     llvm::BasicBlock *notNullBB = Builder.GetInsertBlock();
1269     EmitBlock(contBB);
1270 
1271     llvm::PHINode *PHI = Builder.CreatePHI(result->getType(), 2);
1272     PHI->addIncoming(result, notNullBB);
1273     PHI->addIncoming(llvm::Constant::getNullValue(result->getType()),
1274                      nullCheckBB);
1275 
1276     result = PHI;
1277   }
1278 
1279   return result;
1280 }
1281 
1282 void CodeGenFunction::EmitDeleteCall(const FunctionDecl *DeleteFD,
1283                                      llvm::Value *Ptr,
1284                                      QualType DeleteTy) {
1285   assert(DeleteFD->getOverloadedOperator() == OO_Delete);
1286 
1287   const FunctionProtoType *DeleteFTy =
1288     DeleteFD->getType()->getAs<FunctionProtoType>();
1289 
1290   CallArgList DeleteArgs;
1291 
1292   // Check if we need to pass the size to the delete operator.
1293   llvm::Value *Size = 0;
1294   QualType SizeTy;
1295   if (DeleteFTy->getNumArgs() == 2) {
1296     SizeTy = DeleteFTy->getArgType(1);
1297     CharUnits DeleteTypeSize = getContext().getTypeSizeInChars(DeleteTy);
1298     Size = llvm::ConstantInt::get(ConvertType(SizeTy),
1299                                   DeleteTypeSize.getQuantity());
1300   }
1301 
1302   QualType ArgTy = DeleteFTy->getArgType(0);
1303   llvm::Value *DeletePtr = Builder.CreateBitCast(Ptr, ConvertType(ArgTy));
1304   DeleteArgs.add(RValue::get(DeletePtr), ArgTy);
1305 
1306   if (Size)
1307     DeleteArgs.add(RValue::get(Size), SizeTy);
1308 
1309   // Emit the call to delete.
1310   EmitCall(CGM.getTypes().arrangeFunctionCall(DeleteArgs, DeleteFTy),
1311            CGM.GetAddrOfFunction(DeleteFD), ReturnValueSlot(),
1312            DeleteArgs, DeleteFD);
1313 }
1314 
1315 namespace {
1316   /// Calls the given 'operator delete' on a single object.
1317   struct CallObjectDelete : EHScopeStack::Cleanup {
1318     llvm::Value *Ptr;
1319     const FunctionDecl *OperatorDelete;
1320     QualType ElementType;
1321 
1322     CallObjectDelete(llvm::Value *Ptr,
1323                      const FunctionDecl *OperatorDelete,
1324                      QualType ElementType)
1325       : Ptr(Ptr), OperatorDelete(OperatorDelete), ElementType(ElementType) {}
1326 
1327     void Emit(CodeGenFunction &CGF, Flags flags) {
1328       CGF.EmitDeleteCall(OperatorDelete, Ptr, ElementType);
1329     }
1330   };
1331 }
1332 
1333 /// Emit the code for deleting a single object.
1334 static void EmitObjectDelete(CodeGenFunction &CGF,
1335                              const FunctionDecl *OperatorDelete,
1336                              llvm::Value *Ptr,
1337                              QualType ElementType,
1338                              bool UseGlobalDelete) {
1339   // Find the destructor for the type, if applicable.  If the
1340   // destructor is virtual, we'll just emit the vcall and return.
1341   const CXXDestructorDecl *Dtor = 0;
1342   if (const RecordType *RT = ElementType->getAs<RecordType>()) {
1343     CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
1344     if (RD->hasDefinition() && !RD->hasTrivialDestructor()) {
1345       Dtor = RD->getDestructor();
1346 
1347       if (Dtor->isVirtual()) {
1348         if (UseGlobalDelete) {
1349           // If we're supposed to call the global delete, make sure we do so
1350           // even if the destructor throws.
1351           CGF.EHStack.pushCleanup<CallObjectDelete>(NormalAndEHCleanup,
1352                                                     Ptr, OperatorDelete,
1353                                                     ElementType);
1354         }
1355 
1356         llvm::Type *Ty =
1357           CGF.getTypes().GetFunctionType(
1358                          CGF.getTypes().arrangeCXXDestructor(Dtor, Dtor_Complete));
1359 
1360         llvm::Value *Callee
1361           = CGF.BuildVirtualCall(Dtor,
1362                                  UseGlobalDelete? Dtor_Complete : Dtor_Deleting,
1363                                  Ptr, Ty);
1364         CGF.EmitCXXMemberCall(Dtor, Callee, ReturnValueSlot(), Ptr, /*VTT=*/0,
1365                               0, 0);
1366 
1367         if (UseGlobalDelete) {
1368           CGF.PopCleanupBlock();
1369         }
1370 
1371         return;
1372       }
1373     }
1374   }
1375 
1376   // Make sure that we call delete even if the dtor throws.
1377   // This doesn't have to a conditional cleanup because we're going
1378   // to pop it off in a second.
1379   CGF.EHStack.pushCleanup<CallObjectDelete>(NormalAndEHCleanup,
1380                                             Ptr, OperatorDelete, ElementType);
1381 
1382   if (Dtor)
1383     CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
1384                               /*ForVirtualBase=*/false, Ptr);
1385   else if (CGF.getLangOpts().ObjCAutoRefCount &&
1386            ElementType->isObjCLifetimeType()) {
1387     switch (ElementType.getObjCLifetime()) {
1388     case Qualifiers::OCL_None:
1389     case Qualifiers::OCL_ExplicitNone:
1390     case Qualifiers::OCL_Autoreleasing:
1391       break;
1392 
1393     case Qualifiers::OCL_Strong: {
1394       // Load the pointer value.
1395       llvm::Value *PtrValue = CGF.Builder.CreateLoad(Ptr,
1396                                              ElementType.isVolatileQualified());
1397 
1398       CGF.EmitARCRelease(PtrValue, /*precise*/ true);
1399       break;
1400     }
1401 
1402     case Qualifiers::OCL_Weak:
1403       CGF.EmitARCDestroyWeak(Ptr);
1404       break;
1405     }
1406   }
1407 
1408   CGF.PopCleanupBlock();
1409 }
1410 
1411 namespace {
1412   /// Calls the given 'operator delete' on an array of objects.
1413   struct CallArrayDelete : EHScopeStack::Cleanup {
1414     llvm::Value *Ptr;
1415     const FunctionDecl *OperatorDelete;
1416     llvm::Value *NumElements;
1417     QualType ElementType;
1418     CharUnits CookieSize;
1419 
1420     CallArrayDelete(llvm::Value *Ptr,
1421                     const FunctionDecl *OperatorDelete,
1422                     llvm::Value *NumElements,
1423                     QualType ElementType,
1424                     CharUnits CookieSize)
1425       : Ptr(Ptr), OperatorDelete(OperatorDelete), NumElements(NumElements),
1426         ElementType(ElementType), CookieSize(CookieSize) {}
1427 
1428     void Emit(CodeGenFunction &CGF, Flags flags) {
1429       const FunctionProtoType *DeleteFTy =
1430         OperatorDelete->getType()->getAs<FunctionProtoType>();
1431       assert(DeleteFTy->getNumArgs() == 1 || DeleteFTy->getNumArgs() == 2);
1432 
1433       CallArgList Args;
1434 
1435       // Pass the pointer as the first argument.
1436       QualType VoidPtrTy = DeleteFTy->getArgType(0);
1437       llvm::Value *DeletePtr
1438         = CGF.Builder.CreateBitCast(Ptr, CGF.ConvertType(VoidPtrTy));
1439       Args.add(RValue::get(DeletePtr), VoidPtrTy);
1440 
1441       // Pass the original requested size as the second argument.
1442       if (DeleteFTy->getNumArgs() == 2) {
1443         QualType size_t = DeleteFTy->getArgType(1);
1444         llvm::IntegerType *SizeTy
1445           = cast<llvm::IntegerType>(CGF.ConvertType(size_t));
1446 
1447         CharUnits ElementTypeSize =
1448           CGF.CGM.getContext().getTypeSizeInChars(ElementType);
1449 
1450         // The size of an element, multiplied by the number of elements.
1451         llvm::Value *Size
1452           = llvm::ConstantInt::get(SizeTy, ElementTypeSize.getQuantity());
1453         Size = CGF.Builder.CreateMul(Size, NumElements);
1454 
1455         // Plus the size of the cookie if applicable.
1456         if (!CookieSize.isZero()) {
1457           llvm::Value *CookieSizeV
1458             = llvm::ConstantInt::get(SizeTy, CookieSize.getQuantity());
1459           Size = CGF.Builder.CreateAdd(Size, CookieSizeV);
1460         }
1461 
1462         Args.add(RValue::get(Size), size_t);
1463       }
1464 
1465       // Emit the call to delete.
1466       CGF.EmitCall(CGF.getTypes().arrangeFunctionCall(Args, DeleteFTy),
1467                    CGF.CGM.GetAddrOfFunction(OperatorDelete),
1468                    ReturnValueSlot(), Args, OperatorDelete);
1469     }
1470   };
1471 }
1472 
1473 /// Emit the code for deleting an array of objects.
1474 static void EmitArrayDelete(CodeGenFunction &CGF,
1475                             const CXXDeleteExpr *E,
1476                             llvm::Value *deletedPtr,
1477                             QualType elementType) {
1478   llvm::Value *numElements = 0;
1479   llvm::Value *allocatedPtr = 0;
1480   CharUnits cookieSize;
1481   CGF.CGM.getCXXABI().ReadArrayCookie(CGF, deletedPtr, E, elementType,
1482                                       numElements, allocatedPtr, cookieSize);
1483 
1484   assert(allocatedPtr && "ReadArrayCookie didn't set allocated pointer");
1485 
1486   // Make sure that we call delete even if one of the dtors throws.
1487   const FunctionDecl *operatorDelete = E->getOperatorDelete();
1488   CGF.EHStack.pushCleanup<CallArrayDelete>(NormalAndEHCleanup,
1489                                            allocatedPtr, operatorDelete,
1490                                            numElements, elementType,
1491                                            cookieSize);
1492 
1493   // Destroy the elements.
1494   if (QualType::DestructionKind dtorKind = elementType.isDestructedType()) {
1495     assert(numElements && "no element count for a type with a destructor!");
1496 
1497     llvm::Value *arrayEnd =
1498       CGF.Builder.CreateInBoundsGEP(deletedPtr, numElements, "delete.end");
1499 
1500     // Note that it is legal to allocate a zero-length array, and we
1501     // can never fold the check away because the length should always
1502     // come from a cookie.
1503     CGF.emitArrayDestroy(deletedPtr, arrayEnd, elementType,
1504                          CGF.getDestroyer(dtorKind),
1505                          /*checkZeroLength*/ true,
1506                          CGF.needsEHCleanup(dtorKind));
1507   }
1508 
1509   // Pop the cleanup block.
1510   CGF.PopCleanupBlock();
1511 }
1512 
1513 void CodeGenFunction::EmitCXXDeleteExpr(const CXXDeleteExpr *E) {
1514 
1515   // Get at the argument before we performed the implicit conversion
1516   // to void*.
1517   const Expr *Arg = E->getArgument();
1518   while (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg)) {
1519     if (ICE->getCastKind() != CK_UserDefinedConversion &&
1520         ICE->getType()->isVoidPointerType())
1521       Arg = ICE->getSubExpr();
1522     else
1523       break;
1524   }
1525 
1526   llvm::Value *Ptr = EmitScalarExpr(Arg);
1527 
1528   // Null check the pointer.
1529   llvm::BasicBlock *DeleteNotNull = createBasicBlock("delete.notnull");
1530   llvm::BasicBlock *DeleteEnd = createBasicBlock("delete.end");
1531 
1532   llvm::Value *IsNull = Builder.CreateIsNull(Ptr, "isnull");
1533 
1534   Builder.CreateCondBr(IsNull, DeleteEnd, DeleteNotNull);
1535   EmitBlock(DeleteNotNull);
1536 
1537   // We might be deleting a pointer to array.  If so, GEP down to the
1538   // first non-array element.
1539   // (this assumes that A(*)[3][7] is converted to [3 x [7 x %A]]*)
1540   QualType DeleteTy = Arg->getType()->getAs<PointerType>()->getPointeeType();
1541   if (DeleteTy->isConstantArrayType()) {
1542     llvm::Value *Zero = Builder.getInt32(0);
1543     SmallVector<llvm::Value*,8> GEP;
1544 
1545     GEP.push_back(Zero); // point at the outermost array
1546 
1547     // For each layer of array type we're pointing at:
1548     while (const ConstantArrayType *Arr
1549              = getContext().getAsConstantArrayType(DeleteTy)) {
1550       // 1. Unpeel the array type.
1551       DeleteTy = Arr->getElementType();
1552 
1553       // 2. GEP to the first element of the array.
1554       GEP.push_back(Zero);
1555     }
1556 
1557     Ptr = Builder.CreateInBoundsGEP(Ptr, GEP, "del.first");
1558   }
1559 
1560   assert(ConvertTypeForMem(DeleteTy) ==
1561          cast<llvm::PointerType>(Ptr->getType())->getElementType());
1562 
1563   if (E->isArrayForm()) {
1564     EmitArrayDelete(*this, E, Ptr, DeleteTy);
1565   } else {
1566     EmitObjectDelete(*this, E->getOperatorDelete(), Ptr, DeleteTy,
1567                      E->isGlobalDelete());
1568   }
1569 
1570   EmitBlock(DeleteEnd);
1571 }
1572 
1573 static llvm::Constant *getBadTypeidFn(CodeGenFunction &CGF) {
1574   // void __cxa_bad_typeid();
1575   llvm::FunctionType *FTy = llvm::FunctionType::get(CGF.VoidTy, false);
1576 
1577   return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_bad_typeid");
1578 }
1579 
1580 static void EmitBadTypeidCall(CodeGenFunction &CGF) {
1581   llvm::Value *Fn = getBadTypeidFn(CGF);
1582   CGF.EmitCallOrInvoke(Fn).setDoesNotReturn();
1583   CGF.Builder.CreateUnreachable();
1584 }
1585 
1586 static llvm::Value *EmitTypeidFromVTable(CodeGenFunction &CGF,
1587                                          const Expr *E,
1588                                          llvm::Type *StdTypeInfoPtrTy) {
1589   // Get the vtable pointer.
1590   llvm::Value *ThisPtr = CGF.EmitLValue(E).getAddress();
1591 
1592   // C++ [expr.typeid]p2:
1593   //   If the glvalue expression is obtained by applying the unary * operator to
1594   //   a pointer and the pointer is a null pointer value, the typeid expression
1595   //   throws the std::bad_typeid exception.
1596   if (const UnaryOperator *UO = dyn_cast<UnaryOperator>(E->IgnoreParens())) {
1597     if (UO->getOpcode() == UO_Deref) {
1598       llvm::BasicBlock *BadTypeidBlock =
1599         CGF.createBasicBlock("typeid.bad_typeid");
1600       llvm::BasicBlock *EndBlock =
1601         CGF.createBasicBlock("typeid.end");
1602 
1603       llvm::Value *IsNull = CGF.Builder.CreateIsNull(ThisPtr);
1604       CGF.Builder.CreateCondBr(IsNull, BadTypeidBlock, EndBlock);
1605 
1606       CGF.EmitBlock(BadTypeidBlock);
1607       EmitBadTypeidCall(CGF);
1608       CGF.EmitBlock(EndBlock);
1609     }
1610   }
1611 
1612   llvm::Value *Value = CGF.GetVTablePtr(ThisPtr,
1613                                         StdTypeInfoPtrTy->getPointerTo());
1614 
1615   // Load the type info.
1616   Value = CGF.Builder.CreateConstInBoundsGEP1_64(Value, -1ULL);
1617   return CGF.Builder.CreateLoad(Value);
1618 }
1619 
1620 llvm::Value *CodeGenFunction::EmitCXXTypeidExpr(const CXXTypeidExpr *E) {
1621   llvm::Type *StdTypeInfoPtrTy =
1622     ConvertType(E->getType())->getPointerTo();
1623 
1624   if (E->isTypeOperand()) {
1625     llvm::Constant *TypeInfo =
1626       CGM.GetAddrOfRTTIDescriptor(E->getTypeOperand());
1627     return Builder.CreateBitCast(TypeInfo, StdTypeInfoPtrTy);
1628   }
1629 
1630   // C++ [expr.typeid]p2:
1631   //   When typeid is applied to a glvalue expression whose type is a
1632   //   polymorphic class type, the result refers to a std::type_info object
1633   //   representing the type of the most derived object (that is, the dynamic
1634   //   type) to which the glvalue refers.
1635   if (E->getExprOperand()->isGLValue()) {
1636     if (const RecordType *RT =
1637           E->getExprOperand()->getType()->getAs<RecordType>()) {
1638       const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
1639       if (RD->isPolymorphic())
1640         return EmitTypeidFromVTable(*this, E->getExprOperand(),
1641                                     StdTypeInfoPtrTy);
1642     }
1643   }
1644 
1645   QualType OperandTy = E->getExprOperand()->getType();
1646   return Builder.CreateBitCast(CGM.GetAddrOfRTTIDescriptor(OperandTy),
1647                                StdTypeInfoPtrTy);
1648 }
1649 
1650 static llvm::Constant *getDynamicCastFn(CodeGenFunction &CGF) {
1651   // void *__dynamic_cast(const void *sub,
1652   //                      const abi::__class_type_info *src,
1653   //                      const abi::__class_type_info *dst,
1654   //                      std::ptrdiff_t src2dst_offset);
1655 
1656   llvm::Type *Int8PtrTy = CGF.Int8PtrTy;
1657   llvm::Type *PtrDiffTy =
1658     CGF.ConvertType(CGF.getContext().getPointerDiffType());
1659 
1660   llvm::Type *Args[4] = { Int8PtrTy, Int8PtrTy, Int8PtrTy, PtrDiffTy };
1661 
1662   llvm::FunctionType *FTy =
1663     llvm::FunctionType::get(Int8PtrTy, Args, false);
1664 
1665   return CGF.CGM.CreateRuntimeFunction(FTy, "__dynamic_cast");
1666 }
1667 
1668 static llvm::Constant *getBadCastFn(CodeGenFunction &CGF) {
1669   // void __cxa_bad_cast();
1670   llvm::FunctionType *FTy = llvm::FunctionType::get(CGF.VoidTy, false);
1671   return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_bad_cast");
1672 }
1673 
1674 static void EmitBadCastCall(CodeGenFunction &CGF) {
1675   llvm::Value *Fn = getBadCastFn(CGF);
1676   CGF.EmitCallOrInvoke(Fn).setDoesNotReturn();
1677   CGF.Builder.CreateUnreachable();
1678 }
1679 
1680 static llvm::Value *
1681 EmitDynamicCastCall(CodeGenFunction &CGF, llvm::Value *Value,
1682                     QualType SrcTy, QualType DestTy,
1683                     llvm::BasicBlock *CastEnd) {
1684   llvm::Type *PtrDiffLTy =
1685     CGF.ConvertType(CGF.getContext().getPointerDiffType());
1686   llvm::Type *DestLTy = CGF.ConvertType(DestTy);
1687 
1688   if (const PointerType *PTy = DestTy->getAs<PointerType>()) {
1689     if (PTy->getPointeeType()->isVoidType()) {
1690       // C++ [expr.dynamic.cast]p7:
1691       //   If T is "pointer to cv void," then the result is a pointer to the
1692       //   most derived object pointed to by v.
1693 
1694       // Get the vtable pointer.
1695       llvm::Value *VTable = CGF.GetVTablePtr(Value, PtrDiffLTy->getPointerTo());
1696 
1697       // Get the offset-to-top from the vtable.
1698       llvm::Value *OffsetToTop =
1699         CGF.Builder.CreateConstInBoundsGEP1_64(VTable, -2ULL);
1700       OffsetToTop = CGF.Builder.CreateLoad(OffsetToTop, "offset.to.top");
1701 
1702       // Finally, add the offset to the pointer.
1703       Value = CGF.EmitCastToVoidPtr(Value);
1704       Value = CGF.Builder.CreateInBoundsGEP(Value, OffsetToTop);
1705 
1706       return CGF.Builder.CreateBitCast(Value, DestLTy);
1707     }
1708   }
1709 
1710   QualType SrcRecordTy;
1711   QualType DestRecordTy;
1712 
1713   if (const PointerType *DestPTy = DestTy->getAs<PointerType>()) {
1714     SrcRecordTy = SrcTy->castAs<PointerType>()->getPointeeType();
1715     DestRecordTy = DestPTy->getPointeeType();
1716   } else {
1717     SrcRecordTy = SrcTy;
1718     DestRecordTy = DestTy->castAs<ReferenceType>()->getPointeeType();
1719   }
1720 
1721   assert(SrcRecordTy->isRecordType() && "source type must be a record type!");
1722   assert(DestRecordTy->isRecordType() && "dest type must be a record type!");
1723 
1724   llvm::Value *SrcRTTI =
1725     CGF.CGM.GetAddrOfRTTIDescriptor(SrcRecordTy.getUnqualifiedType());
1726   llvm::Value *DestRTTI =
1727     CGF.CGM.GetAddrOfRTTIDescriptor(DestRecordTy.getUnqualifiedType());
1728 
1729   // FIXME: Actually compute a hint here.
1730   llvm::Value *OffsetHint = llvm::ConstantInt::get(PtrDiffLTy, -1ULL);
1731 
1732   // Emit the call to __dynamic_cast.
1733   Value = CGF.EmitCastToVoidPtr(Value);
1734   Value = CGF.Builder.CreateCall4(getDynamicCastFn(CGF), Value,
1735                                   SrcRTTI, DestRTTI, OffsetHint);
1736   Value = CGF.Builder.CreateBitCast(Value, DestLTy);
1737 
1738   /// C++ [expr.dynamic.cast]p9:
1739   ///   A failed cast to reference type throws std::bad_cast
1740   if (DestTy->isReferenceType()) {
1741     llvm::BasicBlock *BadCastBlock =
1742       CGF.createBasicBlock("dynamic_cast.bad_cast");
1743 
1744     llvm::Value *IsNull = CGF.Builder.CreateIsNull(Value);
1745     CGF.Builder.CreateCondBr(IsNull, BadCastBlock, CastEnd);
1746 
1747     CGF.EmitBlock(BadCastBlock);
1748     EmitBadCastCall(CGF);
1749   }
1750 
1751   return Value;
1752 }
1753 
1754 static llvm::Value *EmitDynamicCastToNull(CodeGenFunction &CGF,
1755                                           QualType DestTy) {
1756   llvm::Type *DestLTy = CGF.ConvertType(DestTy);
1757   if (DestTy->isPointerType())
1758     return llvm::Constant::getNullValue(DestLTy);
1759 
1760   /// C++ [expr.dynamic.cast]p9:
1761   ///   A failed cast to reference type throws std::bad_cast
1762   EmitBadCastCall(CGF);
1763 
1764   CGF.EmitBlock(CGF.createBasicBlock("dynamic_cast.end"));
1765   return llvm::UndefValue::get(DestLTy);
1766 }
1767 
1768 llvm::Value *CodeGenFunction::EmitDynamicCast(llvm::Value *Value,
1769                                               const CXXDynamicCastExpr *DCE) {
1770   QualType DestTy = DCE->getTypeAsWritten();
1771 
1772   if (DCE->isAlwaysNull())
1773     return EmitDynamicCastToNull(*this, DestTy);
1774 
1775   QualType SrcTy = DCE->getSubExpr()->getType();
1776 
1777   // C++ [expr.dynamic.cast]p4:
1778   //   If the value of v is a null pointer value in the pointer case, the result
1779   //   is the null pointer value of type T.
1780   bool ShouldNullCheckSrcValue = SrcTy->isPointerType();
1781 
1782   llvm::BasicBlock *CastNull = 0;
1783   llvm::BasicBlock *CastNotNull = 0;
1784   llvm::BasicBlock *CastEnd = createBasicBlock("dynamic_cast.end");
1785 
1786   if (ShouldNullCheckSrcValue) {
1787     CastNull = createBasicBlock("dynamic_cast.null");
1788     CastNotNull = createBasicBlock("dynamic_cast.notnull");
1789 
1790     llvm::Value *IsNull = Builder.CreateIsNull(Value);
1791     Builder.CreateCondBr(IsNull, CastNull, CastNotNull);
1792     EmitBlock(CastNotNull);
1793   }
1794 
1795   Value = EmitDynamicCastCall(*this, Value, SrcTy, DestTy, CastEnd);
1796 
1797   if (ShouldNullCheckSrcValue) {
1798     EmitBranch(CastEnd);
1799 
1800     EmitBlock(CastNull);
1801     EmitBranch(CastEnd);
1802   }
1803 
1804   EmitBlock(CastEnd);
1805 
1806   if (ShouldNullCheckSrcValue) {
1807     llvm::PHINode *PHI = Builder.CreatePHI(Value->getType(), 2);
1808     PHI->addIncoming(Value, CastNotNull);
1809     PHI->addIncoming(llvm::Constant::getNullValue(Value->getType()), CastNull);
1810 
1811     Value = PHI;
1812   }
1813 
1814   return Value;
1815 }
1816 
1817 void CodeGenFunction::EmitLambdaExpr(const LambdaExpr *E, AggValueSlot Slot) {
1818   RunCleanupsScope Scope(*this);
1819 
1820   CXXRecordDecl::field_iterator CurField = E->getLambdaClass()->field_begin();
1821   for (LambdaExpr::capture_init_iterator i = E->capture_init_begin(),
1822                                          e = E->capture_init_end();
1823        i != e; ++i, ++CurField) {
1824     // Emit initialization
1825     LValue LV = EmitLValueForFieldInitialization(Slot.getAddr(), *CurField, 0);
1826     ArrayRef<VarDecl *> ArrayIndexes;
1827     if (CurField->getType()->isArrayType())
1828       ArrayIndexes = E->getCaptureInitIndexVars(i);
1829     EmitInitializerForField(*CurField, LV, *i, ArrayIndexes);
1830   }
1831 }
1832