xref: /freebsd/contrib/llvm-project/clang/lib/CodeGen/CGClass.cpp (revision c1d255d3ffdbe447de3ab875bf4e7d7accc5bfc5)
1 //===--- CGClass.cpp - Emit LLVM Code for C++ classes -----------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This contains code dealing with C++ code generation of classes
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "CGBlocks.h"
14 #include "CGCXXABI.h"
15 #include "CGDebugInfo.h"
16 #include "CGRecordLayout.h"
17 #include "CodeGenFunction.h"
18 #include "TargetInfo.h"
19 #include "clang/AST/Attr.h"
20 #include "clang/AST/CXXInheritance.h"
21 #include "clang/AST/CharUnits.h"
22 #include "clang/AST/DeclTemplate.h"
23 #include "clang/AST/EvaluatedExprVisitor.h"
24 #include "clang/AST/RecordLayout.h"
25 #include "clang/AST/StmtCXX.h"
26 #include "clang/Basic/CodeGenOptions.h"
27 #include "clang/Basic/TargetBuiltins.h"
28 #include "clang/CodeGen/CGFunctionInfo.h"
29 #include "llvm/IR/Intrinsics.h"
30 #include "llvm/IR/Metadata.h"
31 #include "llvm/Transforms/Utils/SanitizerStats.h"
32 
33 using namespace clang;
34 using namespace CodeGen;
35 
36 /// Return the best known alignment for an unknown pointer to a
37 /// particular class.
38 CharUnits CodeGenModule::getClassPointerAlignment(const CXXRecordDecl *RD) {
39   if (!RD->hasDefinition())
40     return CharUnits::One(); // Hopefully won't be used anywhere.
41 
42   auto &layout = getContext().getASTRecordLayout(RD);
43 
44   // If the class is final, then we know that the pointer points to an
45   // object of that type and can use the full alignment.
46   if (RD->isEffectivelyFinal())
47     return layout.getAlignment();
48 
49   // Otherwise, we have to assume it could be a subclass.
50   return layout.getNonVirtualAlignment();
51 }
52 
53 /// Return the smallest possible amount of storage that might be allocated
54 /// starting from the beginning of an object of a particular class.
55 ///
56 /// This may be smaller than sizeof(RD) if RD has virtual base classes.
57 CharUnits CodeGenModule::getMinimumClassObjectSize(const CXXRecordDecl *RD) {
58   if (!RD->hasDefinition())
59     return CharUnits::One();
60 
61   auto &layout = getContext().getASTRecordLayout(RD);
62 
63   // If the class is final, then we know that the pointer points to an
64   // object of that type and can use the full alignment.
65   if (RD->isEffectivelyFinal())
66     return layout.getSize();
67 
68   // Otherwise, we have to assume it could be a subclass.
69   return std::max(layout.getNonVirtualSize(), CharUnits::One());
70 }
71 
72 /// Return the best known alignment for a pointer to a virtual base,
73 /// given the alignment of a pointer to the derived class.
74 CharUnits CodeGenModule::getVBaseAlignment(CharUnits actualDerivedAlign,
75                                            const CXXRecordDecl *derivedClass,
76                                            const CXXRecordDecl *vbaseClass) {
77   // The basic idea here is that an underaligned derived pointer might
78   // indicate an underaligned base pointer.
79 
80   assert(vbaseClass->isCompleteDefinition());
81   auto &baseLayout = getContext().getASTRecordLayout(vbaseClass);
82   CharUnits expectedVBaseAlign = baseLayout.getNonVirtualAlignment();
83 
84   return getDynamicOffsetAlignment(actualDerivedAlign, derivedClass,
85                                    expectedVBaseAlign);
86 }
87 
88 CharUnits
89 CodeGenModule::getDynamicOffsetAlignment(CharUnits actualBaseAlign,
90                                          const CXXRecordDecl *baseDecl,
91                                          CharUnits expectedTargetAlign) {
92   // If the base is an incomplete type (which is, alas, possible with
93   // member pointers), be pessimistic.
94   if (!baseDecl->isCompleteDefinition())
95     return std::min(actualBaseAlign, expectedTargetAlign);
96 
97   auto &baseLayout = getContext().getASTRecordLayout(baseDecl);
98   CharUnits expectedBaseAlign = baseLayout.getNonVirtualAlignment();
99 
100   // If the class is properly aligned, assume the target offset is, too.
101   //
102   // This actually isn't necessarily the right thing to do --- if the
103   // class is a complete object, but it's only properly aligned for a
104   // base subobject, then the alignments of things relative to it are
105   // probably off as well.  (Note that this requires the alignment of
106   // the target to be greater than the NV alignment of the derived
107   // class.)
108   //
109   // However, our approach to this kind of under-alignment can only
110   // ever be best effort; after all, we're never going to propagate
111   // alignments through variables or parameters.  Note, in particular,
112   // that constructing a polymorphic type in an address that's less
113   // than pointer-aligned will generally trap in the constructor,
114   // unless we someday add some sort of attribute to change the
115   // assumed alignment of 'this'.  So our goal here is pretty much
116   // just to allow the user to explicitly say that a pointer is
117   // under-aligned and then safely access its fields and vtables.
118   if (actualBaseAlign >= expectedBaseAlign) {
119     return expectedTargetAlign;
120   }
121 
122   // Otherwise, we might be offset by an arbitrary multiple of the
123   // actual alignment.  The correct adjustment is to take the min of
124   // the two alignments.
125   return std::min(actualBaseAlign, expectedTargetAlign);
126 }
127 
128 Address CodeGenFunction::LoadCXXThisAddress() {
129   assert(CurFuncDecl && "loading 'this' without a func declaration?");
130   assert(isa<CXXMethodDecl>(CurFuncDecl));
131 
132   // Lazily compute CXXThisAlignment.
133   if (CXXThisAlignment.isZero()) {
134     // Just use the best known alignment for the parent.
135     // TODO: if we're currently emitting a complete-object ctor/dtor,
136     // we can always use the complete-object alignment.
137     auto RD = cast<CXXMethodDecl>(CurFuncDecl)->getParent();
138     CXXThisAlignment = CGM.getClassPointerAlignment(RD);
139   }
140 
141   return Address(LoadCXXThis(), CXXThisAlignment);
142 }
143 
144 /// Emit the address of a field using a member data pointer.
145 ///
146 /// \param E Only used for emergency diagnostics
147 Address
148 CodeGenFunction::EmitCXXMemberDataPointerAddress(const Expr *E, Address base,
149                                                  llvm::Value *memberPtr,
150                                       const MemberPointerType *memberPtrType,
151                                                  LValueBaseInfo *BaseInfo,
152                                                  TBAAAccessInfo *TBAAInfo) {
153   // Ask the ABI to compute the actual address.
154   llvm::Value *ptr =
155     CGM.getCXXABI().EmitMemberDataPointerAddress(*this, E, base,
156                                                  memberPtr, memberPtrType);
157 
158   QualType memberType = memberPtrType->getPointeeType();
159   CharUnits memberAlign =
160       CGM.getNaturalTypeAlignment(memberType, BaseInfo, TBAAInfo);
161   memberAlign =
162     CGM.getDynamicOffsetAlignment(base.getAlignment(),
163                             memberPtrType->getClass()->getAsCXXRecordDecl(),
164                                   memberAlign);
165   return Address(ptr, memberAlign);
166 }
167 
168 CharUnits CodeGenModule::computeNonVirtualBaseClassOffset(
169     const CXXRecordDecl *DerivedClass, CastExpr::path_const_iterator Start,
170     CastExpr::path_const_iterator End) {
171   CharUnits Offset = CharUnits::Zero();
172 
173   const ASTContext &Context = getContext();
174   const CXXRecordDecl *RD = DerivedClass;
175 
176   for (CastExpr::path_const_iterator I = Start; I != End; ++I) {
177     const CXXBaseSpecifier *Base = *I;
178     assert(!Base->isVirtual() && "Should not see virtual bases here!");
179 
180     // Get the layout.
181     const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
182 
183     const auto *BaseDecl =
184         cast<CXXRecordDecl>(Base->getType()->castAs<RecordType>()->getDecl());
185 
186     // Add the offset.
187     Offset += Layout.getBaseClassOffset(BaseDecl);
188 
189     RD = BaseDecl;
190   }
191 
192   return Offset;
193 }
194 
195 llvm::Constant *
196 CodeGenModule::GetNonVirtualBaseClassOffset(const CXXRecordDecl *ClassDecl,
197                                    CastExpr::path_const_iterator PathBegin,
198                                    CastExpr::path_const_iterator PathEnd) {
199   assert(PathBegin != PathEnd && "Base path should not be empty!");
200 
201   CharUnits Offset =
202       computeNonVirtualBaseClassOffset(ClassDecl, PathBegin, PathEnd);
203   if (Offset.isZero())
204     return nullptr;
205 
206   llvm::Type *PtrDiffTy =
207   Types.ConvertType(getContext().getPointerDiffType());
208 
209   return llvm::ConstantInt::get(PtrDiffTy, Offset.getQuantity());
210 }
211 
212 /// Gets the address of a direct base class within a complete object.
213 /// This should only be used for (1) non-virtual bases or (2) virtual bases
214 /// when the type is known to be complete (e.g. in complete destructors).
215 ///
216 /// The object pointed to by 'This' is assumed to be non-null.
217 Address
218 CodeGenFunction::GetAddressOfDirectBaseInCompleteClass(Address This,
219                                                    const CXXRecordDecl *Derived,
220                                                    const CXXRecordDecl *Base,
221                                                    bool BaseIsVirtual) {
222   // 'this' must be a pointer (in some address space) to Derived.
223   assert(This.getElementType() == ConvertType(Derived));
224 
225   // Compute the offset of the virtual base.
226   CharUnits Offset;
227   const ASTRecordLayout &Layout = getContext().getASTRecordLayout(Derived);
228   if (BaseIsVirtual)
229     Offset = Layout.getVBaseClassOffset(Base);
230   else
231     Offset = Layout.getBaseClassOffset(Base);
232 
233   // Shift and cast down to the base type.
234   // TODO: for complete types, this should be possible with a GEP.
235   Address V = This;
236   if (!Offset.isZero()) {
237     V = Builder.CreateElementBitCast(V, Int8Ty);
238     V = Builder.CreateConstInBoundsByteGEP(V, Offset);
239   }
240   V = Builder.CreateElementBitCast(V, ConvertType(Base));
241 
242   return V;
243 }
244 
245 static Address
246 ApplyNonVirtualAndVirtualOffset(CodeGenFunction &CGF, Address addr,
247                                 CharUnits nonVirtualOffset,
248                                 llvm::Value *virtualOffset,
249                                 const CXXRecordDecl *derivedClass,
250                                 const CXXRecordDecl *nearestVBase) {
251   // Assert that we have something to do.
252   assert(!nonVirtualOffset.isZero() || virtualOffset != nullptr);
253 
254   // Compute the offset from the static and dynamic components.
255   llvm::Value *baseOffset;
256   if (!nonVirtualOffset.isZero()) {
257     llvm::Type *OffsetType =
258         (CGF.CGM.getTarget().getCXXABI().isItaniumFamily() &&
259          CGF.CGM.getItaniumVTableContext().isRelativeLayout())
260             ? CGF.Int32Ty
261             : CGF.PtrDiffTy;
262     baseOffset =
263         llvm::ConstantInt::get(OffsetType, nonVirtualOffset.getQuantity());
264     if (virtualOffset) {
265       baseOffset = CGF.Builder.CreateAdd(virtualOffset, baseOffset);
266     }
267   } else {
268     baseOffset = virtualOffset;
269   }
270 
271   // Apply the base offset.
272   llvm::Value *ptr = addr.getPointer();
273   unsigned AddrSpace = ptr->getType()->getPointerAddressSpace();
274   ptr = CGF.Builder.CreateBitCast(ptr, CGF.Int8Ty->getPointerTo(AddrSpace));
275   ptr = CGF.Builder.CreateInBoundsGEP(ptr, baseOffset, "add.ptr");
276 
277   // If we have a virtual component, the alignment of the result will
278   // be relative only to the known alignment of that vbase.
279   CharUnits alignment;
280   if (virtualOffset) {
281     assert(nearestVBase && "virtual offset without vbase?");
282     alignment = CGF.CGM.getVBaseAlignment(addr.getAlignment(),
283                                           derivedClass, nearestVBase);
284   } else {
285     alignment = addr.getAlignment();
286   }
287   alignment = alignment.alignmentAtOffset(nonVirtualOffset);
288 
289   return Address(ptr, alignment);
290 }
291 
292 Address CodeGenFunction::GetAddressOfBaseClass(
293     Address Value, const CXXRecordDecl *Derived,
294     CastExpr::path_const_iterator PathBegin,
295     CastExpr::path_const_iterator PathEnd, bool NullCheckValue,
296     SourceLocation Loc) {
297   assert(PathBegin != PathEnd && "Base path should not be empty!");
298 
299   CastExpr::path_const_iterator Start = PathBegin;
300   const CXXRecordDecl *VBase = nullptr;
301 
302   // Sema has done some convenient canonicalization here: if the
303   // access path involved any virtual steps, the conversion path will
304   // *start* with a step down to the correct virtual base subobject,
305   // and hence will not require any further steps.
306   if ((*Start)->isVirtual()) {
307     VBase = cast<CXXRecordDecl>(
308         (*Start)->getType()->castAs<RecordType>()->getDecl());
309     ++Start;
310   }
311 
312   // Compute the static offset of the ultimate destination within its
313   // allocating subobject (the virtual base, if there is one, or else
314   // the "complete" object that we see).
315   CharUnits NonVirtualOffset = CGM.computeNonVirtualBaseClassOffset(
316       VBase ? VBase : Derived, Start, PathEnd);
317 
318   // If there's a virtual step, we can sometimes "devirtualize" it.
319   // For now, that's limited to when the derived type is final.
320   // TODO: "devirtualize" this for accesses to known-complete objects.
321   if (VBase && Derived->hasAttr<FinalAttr>()) {
322     const ASTRecordLayout &layout = getContext().getASTRecordLayout(Derived);
323     CharUnits vBaseOffset = layout.getVBaseClassOffset(VBase);
324     NonVirtualOffset += vBaseOffset;
325     VBase = nullptr; // we no longer have a virtual step
326   }
327 
328   // Get the base pointer type.
329   llvm::Type *BasePtrTy =
330       ConvertType((PathEnd[-1])->getType())
331           ->getPointerTo(Value.getType()->getPointerAddressSpace());
332 
333   QualType DerivedTy = getContext().getRecordType(Derived);
334   CharUnits DerivedAlign = CGM.getClassPointerAlignment(Derived);
335 
336   // If the static offset is zero and we don't have a virtual step,
337   // just do a bitcast; null checks are unnecessary.
338   if (NonVirtualOffset.isZero() && !VBase) {
339     if (sanitizePerformTypeCheck()) {
340       SanitizerSet SkippedChecks;
341       SkippedChecks.set(SanitizerKind::Null, !NullCheckValue);
342       EmitTypeCheck(TCK_Upcast, Loc, Value.getPointer(),
343                     DerivedTy, DerivedAlign, SkippedChecks);
344     }
345     return Builder.CreateBitCast(Value, BasePtrTy);
346   }
347 
348   llvm::BasicBlock *origBB = nullptr;
349   llvm::BasicBlock *endBB = nullptr;
350 
351   // Skip over the offset (and the vtable load) if we're supposed to
352   // null-check the pointer.
353   if (NullCheckValue) {
354     origBB = Builder.GetInsertBlock();
355     llvm::BasicBlock *notNullBB = createBasicBlock("cast.notnull");
356     endBB = createBasicBlock("cast.end");
357 
358     llvm::Value *isNull = Builder.CreateIsNull(Value.getPointer());
359     Builder.CreateCondBr(isNull, endBB, notNullBB);
360     EmitBlock(notNullBB);
361   }
362 
363   if (sanitizePerformTypeCheck()) {
364     SanitizerSet SkippedChecks;
365     SkippedChecks.set(SanitizerKind::Null, true);
366     EmitTypeCheck(VBase ? TCK_UpcastToVirtualBase : TCK_Upcast, Loc,
367                   Value.getPointer(), DerivedTy, DerivedAlign, SkippedChecks);
368   }
369 
370   // Compute the virtual offset.
371   llvm::Value *VirtualOffset = nullptr;
372   if (VBase) {
373     VirtualOffset =
374       CGM.getCXXABI().GetVirtualBaseClassOffset(*this, Value, Derived, VBase);
375   }
376 
377   // Apply both offsets.
378   Value = ApplyNonVirtualAndVirtualOffset(*this, Value, NonVirtualOffset,
379                                           VirtualOffset, Derived, VBase);
380 
381   // Cast to the destination type.
382   Value = Builder.CreateBitCast(Value, BasePtrTy);
383 
384   // Build a phi if we needed a null check.
385   if (NullCheckValue) {
386     llvm::BasicBlock *notNullBB = Builder.GetInsertBlock();
387     Builder.CreateBr(endBB);
388     EmitBlock(endBB);
389 
390     llvm::PHINode *PHI = Builder.CreatePHI(BasePtrTy, 2, "cast.result");
391     PHI->addIncoming(Value.getPointer(), notNullBB);
392     PHI->addIncoming(llvm::Constant::getNullValue(BasePtrTy), origBB);
393     Value = Address(PHI, Value.getAlignment());
394   }
395 
396   return Value;
397 }
398 
399 Address
400 CodeGenFunction::GetAddressOfDerivedClass(Address BaseAddr,
401                                           const CXXRecordDecl *Derived,
402                                         CastExpr::path_const_iterator PathBegin,
403                                           CastExpr::path_const_iterator PathEnd,
404                                           bool NullCheckValue) {
405   assert(PathBegin != PathEnd && "Base path should not be empty!");
406 
407   QualType DerivedTy =
408     getContext().getCanonicalType(getContext().getTagDeclType(Derived));
409   unsigned AddrSpace =
410     BaseAddr.getPointer()->getType()->getPointerAddressSpace();
411   llvm::Type *DerivedPtrTy = ConvertType(DerivedTy)->getPointerTo(AddrSpace);
412 
413   llvm::Value *NonVirtualOffset =
414     CGM.GetNonVirtualBaseClassOffset(Derived, PathBegin, PathEnd);
415 
416   if (!NonVirtualOffset) {
417     // No offset, we can just cast back.
418     return Builder.CreateBitCast(BaseAddr, DerivedPtrTy);
419   }
420 
421   llvm::BasicBlock *CastNull = nullptr;
422   llvm::BasicBlock *CastNotNull = nullptr;
423   llvm::BasicBlock *CastEnd = nullptr;
424 
425   if (NullCheckValue) {
426     CastNull = createBasicBlock("cast.null");
427     CastNotNull = createBasicBlock("cast.notnull");
428     CastEnd = createBasicBlock("cast.end");
429 
430     llvm::Value *IsNull = Builder.CreateIsNull(BaseAddr.getPointer());
431     Builder.CreateCondBr(IsNull, CastNull, CastNotNull);
432     EmitBlock(CastNotNull);
433   }
434 
435   // Apply the offset.
436   llvm::Value *Value = Builder.CreateBitCast(BaseAddr.getPointer(), Int8PtrTy);
437   Value = Builder.CreateInBoundsGEP(Value, Builder.CreateNeg(NonVirtualOffset),
438                                     "sub.ptr");
439 
440   // Just cast.
441   Value = Builder.CreateBitCast(Value, DerivedPtrTy);
442 
443   // Produce a PHI if we had a null-check.
444   if (NullCheckValue) {
445     Builder.CreateBr(CastEnd);
446     EmitBlock(CastNull);
447     Builder.CreateBr(CastEnd);
448     EmitBlock(CastEnd);
449 
450     llvm::PHINode *PHI = Builder.CreatePHI(Value->getType(), 2);
451     PHI->addIncoming(Value, CastNotNull);
452     PHI->addIncoming(llvm::Constant::getNullValue(Value->getType()), CastNull);
453     Value = PHI;
454   }
455 
456   return Address(Value, CGM.getClassPointerAlignment(Derived));
457 }
458 
459 llvm::Value *CodeGenFunction::GetVTTParameter(GlobalDecl GD,
460                                               bool ForVirtualBase,
461                                               bool Delegating) {
462   if (!CGM.getCXXABI().NeedsVTTParameter(GD)) {
463     // This constructor/destructor does not need a VTT parameter.
464     return nullptr;
465   }
466 
467   const CXXRecordDecl *RD = cast<CXXMethodDecl>(CurCodeDecl)->getParent();
468   const CXXRecordDecl *Base = cast<CXXMethodDecl>(GD.getDecl())->getParent();
469 
470   llvm::Value *VTT;
471 
472   uint64_t SubVTTIndex;
473 
474   if (Delegating) {
475     // If this is a delegating constructor call, just load the VTT.
476     return LoadCXXVTT();
477   } else if (RD == Base) {
478     // If the record matches the base, this is the complete ctor/dtor
479     // variant calling the base variant in a class with virtual bases.
480     assert(!CGM.getCXXABI().NeedsVTTParameter(CurGD) &&
481            "doing no-op VTT offset in base dtor/ctor?");
482     assert(!ForVirtualBase && "Can't have same class as virtual base!");
483     SubVTTIndex = 0;
484   } else {
485     const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
486     CharUnits BaseOffset = ForVirtualBase ?
487       Layout.getVBaseClassOffset(Base) :
488       Layout.getBaseClassOffset(Base);
489 
490     SubVTTIndex =
491       CGM.getVTables().getSubVTTIndex(RD, BaseSubobject(Base, BaseOffset));
492     assert(SubVTTIndex != 0 && "Sub-VTT index must be greater than zero!");
493   }
494 
495   if (CGM.getCXXABI().NeedsVTTParameter(CurGD)) {
496     // A VTT parameter was passed to the constructor, use it.
497     VTT = LoadCXXVTT();
498     VTT = Builder.CreateConstInBoundsGEP1_64(VTT, SubVTTIndex);
499   } else {
500     // We're the complete constructor, so get the VTT by name.
501     VTT = CGM.getVTables().GetAddrOfVTT(RD);
502     VTT = Builder.CreateConstInBoundsGEP2_64(VTT, 0, SubVTTIndex);
503   }
504 
505   return VTT;
506 }
507 
508 namespace {
509   /// Call the destructor for a direct base class.
510   struct CallBaseDtor final : EHScopeStack::Cleanup {
511     const CXXRecordDecl *BaseClass;
512     bool BaseIsVirtual;
513     CallBaseDtor(const CXXRecordDecl *Base, bool BaseIsVirtual)
514       : BaseClass(Base), BaseIsVirtual(BaseIsVirtual) {}
515 
516     void Emit(CodeGenFunction &CGF, Flags flags) override {
517       const CXXRecordDecl *DerivedClass =
518         cast<CXXMethodDecl>(CGF.CurCodeDecl)->getParent();
519 
520       const CXXDestructorDecl *D = BaseClass->getDestructor();
521       // We are already inside a destructor, so presumably the object being
522       // destroyed should have the expected type.
523       QualType ThisTy = D->getThisObjectType();
524       Address Addr =
525         CGF.GetAddressOfDirectBaseInCompleteClass(CGF.LoadCXXThisAddress(),
526                                                   DerivedClass, BaseClass,
527                                                   BaseIsVirtual);
528       CGF.EmitCXXDestructorCall(D, Dtor_Base, BaseIsVirtual,
529                                 /*Delegating=*/false, Addr, ThisTy);
530     }
531   };
532 
533   /// A visitor which checks whether an initializer uses 'this' in a
534   /// way which requires the vtable to be properly set.
535   struct DynamicThisUseChecker : ConstEvaluatedExprVisitor<DynamicThisUseChecker> {
536     typedef ConstEvaluatedExprVisitor<DynamicThisUseChecker> super;
537 
538     bool UsesThis;
539 
540     DynamicThisUseChecker(const ASTContext &C) : super(C), UsesThis(false) {}
541 
542     // Black-list all explicit and implicit references to 'this'.
543     //
544     // Do we need to worry about external references to 'this' derived
545     // from arbitrary code?  If so, then anything which runs arbitrary
546     // external code might potentially access the vtable.
547     void VisitCXXThisExpr(const CXXThisExpr *E) { UsesThis = true; }
548   };
549 } // end anonymous namespace
550 
551 static bool BaseInitializerUsesThis(ASTContext &C, const Expr *Init) {
552   DynamicThisUseChecker Checker(C);
553   Checker.Visit(Init);
554   return Checker.UsesThis;
555 }
556 
557 static void EmitBaseInitializer(CodeGenFunction &CGF,
558                                 const CXXRecordDecl *ClassDecl,
559                                 CXXCtorInitializer *BaseInit) {
560   assert(BaseInit->isBaseInitializer() &&
561          "Must have base initializer!");
562 
563   Address ThisPtr = CGF.LoadCXXThisAddress();
564 
565   const Type *BaseType = BaseInit->getBaseClass();
566   const auto *BaseClassDecl =
567       cast<CXXRecordDecl>(BaseType->castAs<RecordType>()->getDecl());
568 
569   bool isBaseVirtual = BaseInit->isBaseVirtual();
570 
571   // If the initializer for the base (other than the constructor
572   // itself) accesses 'this' in any way, we need to initialize the
573   // vtables.
574   if (BaseInitializerUsesThis(CGF.getContext(), BaseInit->getInit()))
575     CGF.InitializeVTablePointers(ClassDecl);
576 
577   // We can pretend to be a complete class because it only matters for
578   // virtual bases, and we only do virtual bases for complete ctors.
579   Address V =
580     CGF.GetAddressOfDirectBaseInCompleteClass(ThisPtr, ClassDecl,
581                                               BaseClassDecl,
582                                               isBaseVirtual);
583   AggValueSlot AggSlot =
584       AggValueSlot::forAddr(
585           V, Qualifiers(),
586           AggValueSlot::IsDestructed,
587           AggValueSlot::DoesNotNeedGCBarriers,
588           AggValueSlot::IsNotAliased,
589           CGF.getOverlapForBaseInit(ClassDecl, BaseClassDecl, isBaseVirtual));
590 
591   CGF.EmitAggExpr(BaseInit->getInit(), AggSlot);
592 
593   if (CGF.CGM.getLangOpts().Exceptions &&
594       !BaseClassDecl->hasTrivialDestructor())
595     CGF.EHStack.pushCleanup<CallBaseDtor>(EHCleanup, BaseClassDecl,
596                                           isBaseVirtual);
597 }
598 
599 static bool isMemcpyEquivalentSpecialMember(const CXXMethodDecl *D) {
600   auto *CD = dyn_cast<CXXConstructorDecl>(D);
601   if (!(CD && CD->isCopyOrMoveConstructor()) &&
602       !D->isCopyAssignmentOperator() && !D->isMoveAssignmentOperator())
603     return false;
604 
605   // We can emit a memcpy for a trivial copy or move constructor/assignment.
606   if (D->isTrivial() && !D->getParent()->mayInsertExtraPadding())
607     return true;
608 
609   // We *must* emit a memcpy for a defaulted union copy or move op.
610   if (D->getParent()->isUnion() && D->isDefaulted())
611     return true;
612 
613   return false;
614 }
615 
616 static void EmitLValueForAnyFieldInitialization(CodeGenFunction &CGF,
617                                                 CXXCtorInitializer *MemberInit,
618                                                 LValue &LHS) {
619   FieldDecl *Field = MemberInit->getAnyMember();
620   if (MemberInit->isIndirectMemberInitializer()) {
621     // If we are initializing an anonymous union field, drill down to the field.
622     IndirectFieldDecl *IndirectField = MemberInit->getIndirectMember();
623     for (const auto *I : IndirectField->chain())
624       LHS = CGF.EmitLValueForFieldInitialization(LHS, cast<FieldDecl>(I));
625   } else {
626     LHS = CGF.EmitLValueForFieldInitialization(LHS, Field);
627   }
628 }
629 
630 static void EmitMemberInitializer(CodeGenFunction &CGF,
631                                   const CXXRecordDecl *ClassDecl,
632                                   CXXCtorInitializer *MemberInit,
633                                   const CXXConstructorDecl *Constructor,
634                                   FunctionArgList &Args) {
635   ApplyDebugLocation Loc(CGF, MemberInit->getSourceLocation());
636   assert(MemberInit->isAnyMemberInitializer() &&
637          "Must have member initializer!");
638   assert(MemberInit->getInit() && "Must have initializer!");
639 
640   // non-static data member initializers.
641   FieldDecl *Field = MemberInit->getAnyMember();
642   QualType FieldType = Field->getType();
643 
644   llvm::Value *ThisPtr = CGF.LoadCXXThis();
645   QualType RecordTy = CGF.getContext().getTypeDeclType(ClassDecl);
646   LValue LHS;
647 
648   // If a base constructor is being emitted, create an LValue that has the
649   // non-virtual alignment.
650   if (CGF.CurGD.getCtorType() == Ctor_Base)
651     LHS = CGF.MakeNaturalAlignPointeeAddrLValue(ThisPtr, RecordTy);
652   else
653     LHS = CGF.MakeNaturalAlignAddrLValue(ThisPtr, RecordTy);
654 
655   EmitLValueForAnyFieldInitialization(CGF, MemberInit, LHS);
656 
657   // Special case: if we are in a copy or move constructor, and we are copying
658   // an array of PODs or classes with trivial copy constructors, ignore the
659   // AST and perform the copy we know is equivalent.
660   // FIXME: This is hacky at best... if we had a bit more explicit information
661   // in the AST, we could generalize it more easily.
662   const ConstantArrayType *Array
663     = CGF.getContext().getAsConstantArrayType(FieldType);
664   if (Array && Constructor->isDefaulted() &&
665       Constructor->isCopyOrMoveConstructor()) {
666     QualType BaseElementTy = CGF.getContext().getBaseElementType(Array);
667     CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(MemberInit->getInit());
668     if (BaseElementTy.isPODType(CGF.getContext()) ||
669         (CE && isMemcpyEquivalentSpecialMember(CE->getConstructor()))) {
670       unsigned SrcArgIndex =
671           CGF.CGM.getCXXABI().getSrcArgforCopyCtor(Constructor, Args);
672       llvm::Value *SrcPtr
673         = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(Args[SrcArgIndex]));
674       LValue ThisRHSLV = CGF.MakeNaturalAlignAddrLValue(SrcPtr, RecordTy);
675       LValue Src = CGF.EmitLValueForFieldInitialization(ThisRHSLV, Field);
676 
677       // Copy the aggregate.
678       CGF.EmitAggregateCopy(LHS, Src, FieldType, CGF.getOverlapForFieldInit(Field),
679                             LHS.isVolatileQualified());
680       // Ensure that we destroy the objects if an exception is thrown later in
681       // the constructor.
682       QualType::DestructionKind dtorKind = FieldType.isDestructedType();
683       if (CGF.needsEHCleanup(dtorKind))
684         CGF.pushEHDestroy(dtorKind, LHS.getAddress(CGF), FieldType);
685       return;
686     }
687   }
688 
689   CGF.EmitInitializerForField(Field, LHS, MemberInit->getInit());
690 }
691 
692 void CodeGenFunction::EmitInitializerForField(FieldDecl *Field, LValue LHS,
693                                               Expr *Init) {
694   QualType FieldType = Field->getType();
695   switch (getEvaluationKind(FieldType)) {
696   case TEK_Scalar:
697     if (LHS.isSimple()) {
698       EmitExprAsInit(Init, Field, LHS, false);
699     } else {
700       RValue RHS = RValue::get(EmitScalarExpr(Init));
701       EmitStoreThroughLValue(RHS, LHS);
702     }
703     break;
704   case TEK_Complex:
705     EmitComplexExprIntoLValue(Init, LHS, /*isInit*/ true);
706     break;
707   case TEK_Aggregate: {
708     AggValueSlot Slot = AggValueSlot::forLValue(
709         LHS, *this, AggValueSlot::IsDestructed,
710         AggValueSlot::DoesNotNeedGCBarriers, AggValueSlot::IsNotAliased,
711         getOverlapForFieldInit(Field), AggValueSlot::IsNotZeroed,
712         // Checks are made by the code that calls constructor.
713         AggValueSlot::IsSanitizerChecked);
714     EmitAggExpr(Init, Slot);
715     break;
716   }
717   }
718 
719   // Ensure that we destroy this object if an exception is thrown
720   // later in the constructor.
721   QualType::DestructionKind dtorKind = FieldType.isDestructedType();
722   if (needsEHCleanup(dtorKind))
723     pushEHDestroy(dtorKind, LHS.getAddress(*this), FieldType);
724 }
725 
726 /// Checks whether the given constructor is a valid subject for the
727 /// complete-to-base constructor delegation optimization, i.e.
728 /// emitting the complete constructor as a simple call to the base
729 /// constructor.
730 bool CodeGenFunction::IsConstructorDelegationValid(
731     const CXXConstructorDecl *Ctor) {
732 
733   // Currently we disable the optimization for classes with virtual
734   // bases because (1) the addresses of parameter variables need to be
735   // consistent across all initializers but (2) the delegate function
736   // call necessarily creates a second copy of the parameter variable.
737   //
738   // The limiting example (purely theoretical AFAIK):
739   //   struct A { A(int &c) { c++; } };
740   //   struct B : virtual A {
741   //     B(int count) : A(count) { printf("%d\n", count); }
742   //   };
743   // ...although even this example could in principle be emitted as a
744   // delegation since the address of the parameter doesn't escape.
745   if (Ctor->getParent()->getNumVBases()) {
746     // TODO: white-list trivial vbase initializers.  This case wouldn't
747     // be subject to the restrictions below.
748 
749     // TODO: white-list cases where:
750     //  - there are no non-reference parameters to the constructor
751     //  - the initializers don't access any non-reference parameters
752     //  - the initializers don't take the address of non-reference
753     //    parameters
754     //  - etc.
755     // If we ever add any of the above cases, remember that:
756     //  - function-try-blocks will always exclude this optimization
757     //  - we need to perform the constructor prologue and cleanup in
758     //    EmitConstructorBody.
759 
760     return false;
761   }
762 
763   // We also disable the optimization for variadic functions because
764   // it's impossible to "re-pass" varargs.
765   if (Ctor->getType()->castAs<FunctionProtoType>()->isVariadic())
766     return false;
767 
768   // FIXME: Decide if we can do a delegation of a delegating constructor.
769   if (Ctor->isDelegatingConstructor())
770     return false;
771 
772   return true;
773 }
774 
775 // Emit code in ctor (Prologue==true) or dtor (Prologue==false)
776 // to poison the extra field paddings inserted under
777 // -fsanitize-address-field-padding=1|2.
778 void CodeGenFunction::EmitAsanPrologueOrEpilogue(bool Prologue) {
779   ASTContext &Context = getContext();
780   const CXXRecordDecl *ClassDecl =
781       Prologue ? cast<CXXConstructorDecl>(CurGD.getDecl())->getParent()
782                : cast<CXXDestructorDecl>(CurGD.getDecl())->getParent();
783   if (!ClassDecl->mayInsertExtraPadding()) return;
784 
785   struct SizeAndOffset {
786     uint64_t Size;
787     uint64_t Offset;
788   };
789 
790   unsigned PtrSize = CGM.getDataLayout().getPointerSizeInBits();
791   const ASTRecordLayout &Info = Context.getASTRecordLayout(ClassDecl);
792 
793   // Populate sizes and offsets of fields.
794   SmallVector<SizeAndOffset, 16> SSV(Info.getFieldCount());
795   for (unsigned i = 0, e = Info.getFieldCount(); i != e; ++i)
796     SSV[i].Offset =
797         Context.toCharUnitsFromBits(Info.getFieldOffset(i)).getQuantity();
798 
799   size_t NumFields = 0;
800   for (const auto *Field : ClassDecl->fields()) {
801     const FieldDecl *D = Field;
802     auto FieldInfo = Context.getTypeInfoInChars(D->getType());
803     CharUnits FieldSize = FieldInfo.Width;
804     assert(NumFields < SSV.size());
805     SSV[NumFields].Size = D->isBitField() ? 0 : FieldSize.getQuantity();
806     NumFields++;
807   }
808   assert(NumFields == SSV.size());
809   if (SSV.size() <= 1) return;
810 
811   // We will insert calls to __asan_* run-time functions.
812   // LLVM AddressSanitizer pass may decide to inline them later.
813   llvm::Type *Args[2] = {IntPtrTy, IntPtrTy};
814   llvm::FunctionType *FTy =
815       llvm::FunctionType::get(CGM.VoidTy, Args, false);
816   llvm::FunctionCallee F = CGM.CreateRuntimeFunction(
817       FTy, Prologue ? "__asan_poison_intra_object_redzone"
818                     : "__asan_unpoison_intra_object_redzone");
819 
820   llvm::Value *ThisPtr = LoadCXXThis();
821   ThisPtr = Builder.CreatePtrToInt(ThisPtr, IntPtrTy);
822   uint64_t TypeSize = Info.getNonVirtualSize().getQuantity();
823   // For each field check if it has sufficient padding,
824   // if so (un)poison it with a call.
825   for (size_t i = 0; i < SSV.size(); i++) {
826     uint64_t AsanAlignment = 8;
827     uint64_t NextField = i == SSV.size() - 1 ? TypeSize : SSV[i + 1].Offset;
828     uint64_t PoisonSize = NextField - SSV[i].Offset - SSV[i].Size;
829     uint64_t EndOffset = SSV[i].Offset + SSV[i].Size;
830     if (PoisonSize < AsanAlignment || !SSV[i].Size ||
831         (NextField % AsanAlignment) != 0)
832       continue;
833     Builder.CreateCall(
834         F, {Builder.CreateAdd(ThisPtr, Builder.getIntN(PtrSize, EndOffset)),
835             Builder.getIntN(PtrSize, PoisonSize)});
836   }
837 }
838 
839 /// EmitConstructorBody - Emits the body of the current constructor.
840 void CodeGenFunction::EmitConstructorBody(FunctionArgList &Args) {
841   EmitAsanPrologueOrEpilogue(true);
842   const CXXConstructorDecl *Ctor = cast<CXXConstructorDecl>(CurGD.getDecl());
843   CXXCtorType CtorType = CurGD.getCtorType();
844 
845   assert((CGM.getTarget().getCXXABI().hasConstructorVariants() ||
846           CtorType == Ctor_Complete) &&
847          "can only generate complete ctor for this ABI");
848 
849   // Before we go any further, try the complete->base constructor
850   // delegation optimization.
851   if (CtorType == Ctor_Complete && IsConstructorDelegationValid(Ctor) &&
852       CGM.getTarget().getCXXABI().hasConstructorVariants()) {
853     EmitDelegateCXXConstructorCall(Ctor, Ctor_Base, Args, Ctor->getEndLoc());
854     return;
855   }
856 
857   const FunctionDecl *Definition = nullptr;
858   Stmt *Body = Ctor->getBody(Definition);
859   assert(Definition == Ctor && "emitting wrong constructor body");
860 
861   // Enter the function-try-block before the constructor prologue if
862   // applicable.
863   bool IsTryBody = (Body && isa<CXXTryStmt>(Body));
864   if (IsTryBody)
865     EnterCXXTryStmt(*cast<CXXTryStmt>(Body), true);
866 
867   incrementProfileCounter(Body);
868 
869   RunCleanupsScope RunCleanups(*this);
870 
871   // TODO: in restricted cases, we can emit the vbase initializers of
872   // a complete ctor and then delegate to the base ctor.
873 
874   // Emit the constructor prologue, i.e. the base and member
875   // initializers.
876   EmitCtorPrologue(Ctor, CtorType, Args);
877 
878   // Emit the body of the statement.
879   if (IsTryBody)
880     EmitStmt(cast<CXXTryStmt>(Body)->getTryBlock());
881   else if (Body)
882     EmitStmt(Body);
883 
884   // Emit any cleanup blocks associated with the member or base
885   // initializers, which includes (along the exceptional path) the
886   // destructors for those members and bases that were fully
887   // constructed.
888   RunCleanups.ForceCleanup();
889 
890   if (IsTryBody)
891     ExitCXXTryStmt(*cast<CXXTryStmt>(Body), true);
892 }
893 
894 namespace {
895   /// RAII object to indicate that codegen is copying the value representation
896   /// instead of the object representation. Useful when copying a struct or
897   /// class which has uninitialized members and we're only performing
898   /// lvalue-to-rvalue conversion on the object but not its members.
899   class CopyingValueRepresentation {
900   public:
901     explicit CopyingValueRepresentation(CodeGenFunction &CGF)
902         : CGF(CGF), OldSanOpts(CGF.SanOpts) {
903       CGF.SanOpts.set(SanitizerKind::Bool, false);
904       CGF.SanOpts.set(SanitizerKind::Enum, false);
905     }
906     ~CopyingValueRepresentation() {
907       CGF.SanOpts = OldSanOpts;
908     }
909   private:
910     CodeGenFunction &CGF;
911     SanitizerSet OldSanOpts;
912   };
913 } // end anonymous namespace
914 
915 namespace {
916   class FieldMemcpyizer {
917   public:
918     FieldMemcpyizer(CodeGenFunction &CGF, const CXXRecordDecl *ClassDecl,
919                     const VarDecl *SrcRec)
920       : CGF(CGF), ClassDecl(ClassDecl), SrcRec(SrcRec),
921         RecLayout(CGF.getContext().getASTRecordLayout(ClassDecl)),
922         FirstField(nullptr), LastField(nullptr), FirstFieldOffset(0),
923         LastFieldOffset(0), LastAddedFieldIndex(0) {}
924 
925     bool isMemcpyableField(FieldDecl *F) const {
926       // Never memcpy fields when we are adding poisoned paddings.
927       if (CGF.getContext().getLangOpts().SanitizeAddressFieldPadding)
928         return false;
929       Qualifiers Qual = F->getType().getQualifiers();
930       if (Qual.hasVolatile() || Qual.hasObjCLifetime())
931         return false;
932       return true;
933     }
934 
935     void addMemcpyableField(FieldDecl *F) {
936       if (F->isZeroSize(CGF.getContext()))
937         return;
938       if (!FirstField)
939         addInitialField(F);
940       else
941         addNextField(F);
942     }
943 
944     CharUnits getMemcpySize(uint64_t FirstByteOffset) const {
945       ASTContext &Ctx = CGF.getContext();
946       unsigned LastFieldSize =
947           LastField->isBitField()
948               ? LastField->getBitWidthValue(Ctx)
949               : Ctx.toBits(
950                     Ctx.getTypeInfoDataSizeInChars(LastField->getType()).Width);
951       uint64_t MemcpySizeBits = LastFieldOffset + LastFieldSize -
952                                 FirstByteOffset + Ctx.getCharWidth() - 1;
953       CharUnits MemcpySize = Ctx.toCharUnitsFromBits(MemcpySizeBits);
954       return MemcpySize;
955     }
956 
957     void emitMemcpy() {
958       // Give the subclass a chance to bail out if it feels the memcpy isn't
959       // worth it (e.g. Hasn't aggregated enough data).
960       if (!FirstField) {
961         return;
962       }
963 
964       uint64_t FirstByteOffset;
965       if (FirstField->isBitField()) {
966         const CGRecordLayout &RL =
967           CGF.getTypes().getCGRecordLayout(FirstField->getParent());
968         const CGBitFieldInfo &BFInfo = RL.getBitFieldInfo(FirstField);
969         // FirstFieldOffset is not appropriate for bitfields,
970         // we need to use the storage offset instead.
971         FirstByteOffset = CGF.getContext().toBits(BFInfo.StorageOffset);
972       } else {
973         FirstByteOffset = FirstFieldOffset;
974       }
975 
976       CharUnits MemcpySize = getMemcpySize(FirstByteOffset);
977       QualType RecordTy = CGF.getContext().getTypeDeclType(ClassDecl);
978       Address ThisPtr = CGF.LoadCXXThisAddress();
979       LValue DestLV = CGF.MakeAddrLValue(ThisPtr, RecordTy);
980       LValue Dest = CGF.EmitLValueForFieldInitialization(DestLV, FirstField);
981       llvm::Value *SrcPtr = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(SrcRec));
982       LValue SrcLV = CGF.MakeNaturalAlignAddrLValue(SrcPtr, RecordTy);
983       LValue Src = CGF.EmitLValueForFieldInitialization(SrcLV, FirstField);
984 
985       emitMemcpyIR(
986           Dest.isBitField() ? Dest.getBitFieldAddress() : Dest.getAddress(CGF),
987           Src.isBitField() ? Src.getBitFieldAddress() : Src.getAddress(CGF),
988           MemcpySize);
989       reset();
990     }
991 
992     void reset() {
993       FirstField = nullptr;
994     }
995 
996   protected:
997     CodeGenFunction &CGF;
998     const CXXRecordDecl *ClassDecl;
999 
1000   private:
1001     void emitMemcpyIR(Address DestPtr, Address SrcPtr, CharUnits Size) {
1002       llvm::PointerType *DPT = DestPtr.getType();
1003       llvm::Type *DBP =
1004         llvm::Type::getInt8PtrTy(CGF.getLLVMContext(), DPT->getAddressSpace());
1005       DestPtr = CGF.Builder.CreateBitCast(DestPtr, DBP);
1006 
1007       llvm::PointerType *SPT = SrcPtr.getType();
1008       llvm::Type *SBP =
1009         llvm::Type::getInt8PtrTy(CGF.getLLVMContext(), SPT->getAddressSpace());
1010       SrcPtr = CGF.Builder.CreateBitCast(SrcPtr, SBP);
1011 
1012       CGF.Builder.CreateMemCpy(DestPtr, SrcPtr, Size.getQuantity());
1013     }
1014 
1015     void addInitialField(FieldDecl *F) {
1016       FirstField = F;
1017       LastField = F;
1018       FirstFieldOffset = RecLayout.getFieldOffset(F->getFieldIndex());
1019       LastFieldOffset = FirstFieldOffset;
1020       LastAddedFieldIndex = F->getFieldIndex();
1021     }
1022 
1023     void addNextField(FieldDecl *F) {
1024       // For the most part, the following invariant will hold:
1025       //   F->getFieldIndex() == LastAddedFieldIndex + 1
1026       // The one exception is that Sema won't add a copy-initializer for an
1027       // unnamed bitfield, which will show up here as a gap in the sequence.
1028       assert(F->getFieldIndex() >= LastAddedFieldIndex + 1 &&
1029              "Cannot aggregate fields out of order.");
1030       LastAddedFieldIndex = F->getFieldIndex();
1031 
1032       // The 'first' and 'last' fields are chosen by offset, rather than field
1033       // index. This allows the code to support bitfields, as well as regular
1034       // fields.
1035       uint64_t FOffset = RecLayout.getFieldOffset(F->getFieldIndex());
1036       if (FOffset < FirstFieldOffset) {
1037         FirstField = F;
1038         FirstFieldOffset = FOffset;
1039       } else if (FOffset >= LastFieldOffset) {
1040         LastField = F;
1041         LastFieldOffset = FOffset;
1042       }
1043     }
1044 
1045     const VarDecl *SrcRec;
1046     const ASTRecordLayout &RecLayout;
1047     FieldDecl *FirstField;
1048     FieldDecl *LastField;
1049     uint64_t FirstFieldOffset, LastFieldOffset;
1050     unsigned LastAddedFieldIndex;
1051   };
1052 
1053   class ConstructorMemcpyizer : public FieldMemcpyizer {
1054   private:
1055     /// Get source argument for copy constructor. Returns null if not a copy
1056     /// constructor.
1057     static const VarDecl *getTrivialCopySource(CodeGenFunction &CGF,
1058                                                const CXXConstructorDecl *CD,
1059                                                FunctionArgList &Args) {
1060       if (CD->isCopyOrMoveConstructor() && CD->isDefaulted())
1061         return Args[CGF.CGM.getCXXABI().getSrcArgforCopyCtor(CD, Args)];
1062       return nullptr;
1063     }
1064 
1065     // Returns true if a CXXCtorInitializer represents a member initialization
1066     // that can be rolled into a memcpy.
1067     bool isMemberInitMemcpyable(CXXCtorInitializer *MemberInit) const {
1068       if (!MemcpyableCtor)
1069         return false;
1070       FieldDecl *Field = MemberInit->getMember();
1071       assert(Field && "No field for member init.");
1072       QualType FieldType = Field->getType();
1073       CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(MemberInit->getInit());
1074 
1075       // Bail out on non-memcpyable, not-trivially-copyable members.
1076       if (!(CE && isMemcpyEquivalentSpecialMember(CE->getConstructor())) &&
1077           !(FieldType.isTriviallyCopyableType(CGF.getContext()) ||
1078             FieldType->isReferenceType()))
1079         return false;
1080 
1081       // Bail out on volatile fields.
1082       if (!isMemcpyableField(Field))
1083         return false;
1084 
1085       // Otherwise we're good.
1086       return true;
1087     }
1088 
1089   public:
1090     ConstructorMemcpyizer(CodeGenFunction &CGF, const CXXConstructorDecl *CD,
1091                           FunctionArgList &Args)
1092       : FieldMemcpyizer(CGF, CD->getParent(), getTrivialCopySource(CGF, CD, Args)),
1093         ConstructorDecl(CD),
1094         MemcpyableCtor(CD->isDefaulted() &&
1095                        CD->isCopyOrMoveConstructor() &&
1096                        CGF.getLangOpts().getGC() == LangOptions::NonGC),
1097         Args(Args) { }
1098 
1099     void addMemberInitializer(CXXCtorInitializer *MemberInit) {
1100       if (isMemberInitMemcpyable(MemberInit)) {
1101         AggregatedInits.push_back(MemberInit);
1102         addMemcpyableField(MemberInit->getMember());
1103       } else {
1104         emitAggregatedInits();
1105         EmitMemberInitializer(CGF, ConstructorDecl->getParent(), MemberInit,
1106                               ConstructorDecl, Args);
1107       }
1108     }
1109 
1110     void emitAggregatedInits() {
1111       if (AggregatedInits.size() <= 1) {
1112         // This memcpy is too small to be worthwhile. Fall back on default
1113         // codegen.
1114         if (!AggregatedInits.empty()) {
1115           CopyingValueRepresentation CVR(CGF);
1116           EmitMemberInitializer(CGF, ConstructorDecl->getParent(),
1117                                 AggregatedInits[0], ConstructorDecl, Args);
1118           AggregatedInits.clear();
1119         }
1120         reset();
1121         return;
1122       }
1123 
1124       pushEHDestructors();
1125       emitMemcpy();
1126       AggregatedInits.clear();
1127     }
1128 
1129     void pushEHDestructors() {
1130       Address ThisPtr = CGF.LoadCXXThisAddress();
1131       QualType RecordTy = CGF.getContext().getTypeDeclType(ClassDecl);
1132       LValue LHS = CGF.MakeAddrLValue(ThisPtr, RecordTy);
1133 
1134       for (unsigned i = 0; i < AggregatedInits.size(); ++i) {
1135         CXXCtorInitializer *MemberInit = AggregatedInits[i];
1136         QualType FieldType = MemberInit->getAnyMember()->getType();
1137         QualType::DestructionKind dtorKind = FieldType.isDestructedType();
1138         if (!CGF.needsEHCleanup(dtorKind))
1139           continue;
1140         LValue FieldLHS = LHS;
1141         EmitLValueForAnyFieldInitialization(CGF, MemberInit, FieldLHS);
1142         CGF.pushEHDestroy(dtorKind, FieldLHS.getAddress(CGF), FieldType);
1143       }
1144     }
1145 
1146     void finish() {
1147       emitAggregatedInits();
1148     }
1149 
1150   private:
1151     const CXXConstructorDecl *ConstructorDecl;
1152     bool MemcpyableCtor;
1153     FunctionArgList &Args;
1154     SmallVector<CXXCtorInitializer*, 16> AggregatedInits;
1155   };
1156 
1157   class AssignmentMemcpyizer : public FieldMemcpyizer {
1158   private:
1159     // Returns the memcpyable field copied by the given statement, if one
1160     // exists. Otherwise returns null.
1161     FieldDecl *getMemcpyableField(Stmt *S) {
1162       if (!AssignmentsMemcpyable)
1163         return nullptr;
1164       if (BinaryOperator *BO = dyn_cast<BinaryOperator>(S)) {
1165         // Recognise trivial assignments.
1166         if (BO->getOpcode() != BO_Assign)
1167           return nullptr;
1168         MemberExpr *ME = dyn_cast<MemberExpr>(BO->getLHS());
1169         if (!ME)
1170           return nullptr;
1171         FieldDecl *Field = dyn_cast<FieldDecl>(ME->getMemberDecl());
1172         if (!Field || !isMemcpyableField(Field))
1173           return nullptr;
1174         Stmt *RHS = BO->getRHS();
1175         if (ImplicitCastExpr *EC = dyn_cast<ImplicitCastExpr>(RHS))
1176           RHS = EC->getSubExpr();
1177         if (!RHS)
1178           return nullptr;
1179         if (MemberExpr *ME2 = dyn_cast<MemberExpr>(RHS)) {
1180           if (ME2->getMemberDecl() == Field)
1181             return Field;
1182         }
1183         return nullptr;
1184       } else if (CXXMemberCallExpr *MCE = dyn_cast<CXXMemberCallExpr>(S)) {
1185         CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MCE->getCalleeDecl());
1186         if (!(MD && isMemcpyEquivalentSpecialMember(MD)))
1187           return nullptr;
1188         MemberExpr *IOA = dyn_cast<MemberExpr>(MCE->getImplicitObjectArgument());
1189         if (!IOA)
1190           return nullptr;
1191         FieldDecl *Field = dyn_cast<FieldDecl>(IOA->getMemberDecl());
1192         if (!Field || !isMemcpyableField(Field))
1193           return nullptr;
1194         MemberExpr *Arg0 = dyn_cast<MemberExpr>(MCE->getArg(0));
1195         if (!Arg0 || Field != dyn_cast<FieldDecl>(Arg0->getMemberDecl()))
1196           return nullptr;
1197         return Field;
1198       } else if (CallExpr *CE = dyn_cast<CallExpr>(S)) {
1199         FunctionDecl *FD = dyn_cast<FunctionDecl>(CE->getCalleeDecl());
1200         if (!FD || FD->getBuiltinID() != Builtin::BI__builtin_memcpy)
1201           return nullptr;
1202         Expr *DstPtr = CE->getArg(0);
1203         if (ImplicitCastExpr *DC = dyn_cast<ImplicitCastExpr>(DstPtr))
1204           DstPtr = DC->getSubExpr();
1205         UnaryOperator *DUO = dyn_cast<UnaryOperator>(DstPtr);
1206         if (!DUO || DUO->getOpcode() != UO_AddrOf)
1207           return nullptr;
1208         MemberExpr *ME = dyn_cast<MemberExpr>(DUO->getSubExpr());
1209         if (!ME)
1210           return nullptr;
1211         FieldDecl *Field = dyn_cast<FieldDecl>(ME->getMemberDecl());
1212         if (!Field || !isMemcpyableField(Field))
1213           return nullptr;
1214         Expr *SrcPtr = CE->getArg(1);
1215         if (ImplicitCastExpr *SC = dyn_cast<ImplicitCastExpr>(SrcPtr))
1216           SrcPtr = SC->getSubExpr();
1217         UnaryOperator *SUO = dyn_cast<UnaryOperator>(SrcPtr);
1218         if (!SUO || SUO->getOpcode() != UO_AddrOf)
1219           return nullptr;
1220         MemberExpr *ME2 = dyn_cast<MemberExpr>(SUO->getSubExpr());
1221         if (!ME2 || Field != dyn_cast<FieldDecl>(ME2->getMemberDecl()))
1222           return nullptr;
1223         return Field;
1224       }
1225 
1226       return nullptr;
1227     }
1228 
1229     bool AssignmentsMemcpyable;
1230     SmallVector<Stmt*, 16> AggregatedStmts;
1231 
1232   public:
1233     AssignmentMemcpyizer(CodeGenFunction &CGF, const CXXMethodDecl *AD,
1234                          FunctionArgList &Args)
1235       : FieldMemcpyizer(CGF, AD->getParent(), Args[Args.size() - 1]),
1236         AssignmentsMemcpyable(CGF.getLangOpts().getGC() == LangOptions::NonGC) {
1237       assert(Args.size() == 2);
1238     }
1239 
1240     void emitAssignment(Stmt *S) {
1241       FieldDecl *F = getMemcpyableField(S);
1242       if (F) {
1243         addMemcpyableField(F);
1244         AggregatedStmts.push_back(S);
1245       } else {
1246         emitAggregatedStmts();
1247         CGF.EmitStmt(S);
1248       }
1249     }
1250 
1251     void emitAggregatedStmts() {
1252       if (AggregatedStmts.size() <= 1) {
1253         if (!AggregatedStmts.empty()) {
1254           CopyingValueRepresentation CVR(CGF);
1255           CGF.EmitStmt(AggregatedStmts[0]);
1256         }
1257         reset();
1258       }
1259 
1260       emitMemcpy();
1261       AggregatedStmts.clear();
1262     }
1263 
1264     void finish() {
1265       emitAggregatedStmts();
1266     }
1267   };
1268 } // end anonymous namespace
1269 
1270 static bool isInitializerOfDynamicClass(const CXXCtorInitializer *BaseInit) {
1271   const Type *BaseType = BaseInit->getBaseClass();
1272   const auto *BaseClassDecl =
1273       cast<CXXRecordDecl>(BaseType->castAs<RecordType>()->getDecl());
1274   return BaseClassDecl->isDynamicClass();
1275 }
1276 
1277 /// EmitCtorPrologue - This routine generates necessary code to initialize
1278 /// base classes and non-static data members belonging to this constructor.
1279 void CodeGenFunction::EmitCtorPrologue(const CXXConstructorDecl *CD,
1280                                        CXXCtorType CtorType,
1281                                        FunctionArgList &Args) {
1282   if (CD->isDelegatingConstructor())
1283     return EmitDelegatingCXXConstructorCall(CD, Args);
1284 
1285   const CXXRecordDecl *ClassDecl = CD->getParent();
1286 
1287   CXXConstructorDecl::init_const_iterator B = CD->init_begin(),
1288                                           E = CD->init_end();
1289 
1290   // Virtual base initializers first, if any. They aren't needed if:
1291   // - This is a base ctor variant
1292   // - There are no vbases
1293   // - The class is abstract, so a complete object of it cannot be constructed
1294   //
1295   // The check for an abstract class is necessary because sema may not have
1296   // marked virtual base destructors referenced.
1297   bool ConstructVBases = CtorType != Ctor_Base &&
1298                          ClassDecl->getNumVBases() != 0 &&
1299                          !ClassDecl->isAbstract();
1300 
1301   // In the Microsoft C++ ABI, there are no constructor variants. Instead, the
1302   // constructor of a class with virtual bases takes an additional parameter to
1303   // conditionally construct the virtual bases. Emit that check here.
1304   llvm::BasicBlock *BaseCtorContinueBB = nullptr;
1305   if (ConstructVBases &&
1306       !CGM.getTarget().getCXXABI().hasConstructorVariants()) {
1307     BaseCtorContinueBB =
1308         CGM.getCXXABI().EmitCtorCompleteObjectHandler(*this, ClassDecl);
1309     assert(BaseCtorContinueBB);
1310   }
1311 
1312   llvm::Value *const OldThis = CXXThisValue;
1313   for (; B != E && (*B)->isBaseInitializer() && (*B)->isBaseVirtual(); B++) {
1314     if (!ConstructVBases)
1315       continue;
1316     if (CGM.getCodeGenOpts().StrictVTablePointers &&
1317         CGM.getCodeGenOpts().OptimizationLevel > 0 &&
1318         isInitializerOfDynamicClass(*B))
1319       CXXThisValue = Builder.CreateLaunderInvariantGroup(LoadCXXThis());
1320     EmitBaseInitializer(*this, ClassDecl, *B);
1321   }
1322 
1323   if (BaseCtorContinueBB) {
1324     // Complete object handler should continue to the remaining initializers.
1325     Builder.CreateBr(BaseCtorContinueBB);
1326     EmitBlock(BaseCtorContinueBB);
1327   }
1328 
1329   // Then, non-virtual base initializers.
1330   for (; B != E && (*B)->isBaseInitializer(); B++) {
1331     assert(!(*B)->isBaseVirtual());
1332 
1333     if (CGM.getCodeGenOpts().StrictVTablePointers &&
1334         CGM.getCodeGenOpts().OptimizationLevel > 0 &&
1335         isInitializerOfDynamicClass(*B))
1336       CXXThisValue = Builder.CreateLaunderInvariantGroup(LoadCXXThis());
1337     EmitBaseInitializer(*this, ClassDecl, *B);
1338   }
1339 
1340   CXXThisValue = OldThis;
1341 
1342   InitializeVTablePointers(ClassDecl);
1343 
1344   // And finally, initialize class members.
1345   FieldConstructionScope FCS(*this, LoadCXXThisAddress());
1346   ConstructorMemcpyizer CM(*this, CD, Args);
1347   for (; B != E; B++) {
1348     CXXCtorInitializer *Member = (*B);
1349     assert(!Member->isBaseInitializer());
1350     assert(Member->isAnyMemberInitializer() &&
1351            "Delegating initializer on non-delegating constructor");
1352     CM.addMemberInitializer(Member);
1353   }
1354   CM.finish();
1355 }
1356 
1357 static bool
1358 FieldHasTrivialDestructorBody(ASTContext &Context, const FieldDecl *Field);
1359 
1360 static bool
1361 HasTrivialDestructorBody(ASTContext &Context,
1362                          const CXXRecordDecl *BaseClassDecl,
1363                          const CXXRecordDecl *MostDerivedClassDecl)
1364 {
1365   // If the destructor is trivial we don't have to check anything else.
1366   if (BaseClassDecl->hasTrivialDestructor())
1367     return true;
1368 
1369   if (!BaseClassDecl->getDestructor()->hasTrivialBody())
1370     return false;
1371 
1372   // Check fields.
1373   for (const auto *Field : BaseClassDecl->fields())
1374     if (!FieldHasTrivialDestructorBody(Context, Field))
1375       return false;
1376 
1377   // Check non-virtual bases.
1378   for (const auto &I : BaseClassDecl->bases()) {
1379     if (I.isVirtual())
1380       continue;
1381 
1382     const CXXRecordDecl *NonVirtualBase =
1383       cast<CXXRecordDecl>(I.getType()->castAs<RecordType>()->getDecl());
1384     if (!HasTrivialDestructorBody(Context, NonVirtualBase,
1385                                   MostDerivedClassDecl))
1386       return false;
1387   }
1388 
1389   if (BaseClassDecl == MostDerivedClassDecl) {
1390     // Check virtual bases.
1391     for (const auto &I : BaseClassDecl->vbases()) {
1392       const CXXRecordDecl *VirtualBase =
1393         cast<CXXRecordDecl>(I.getType()->castAs<RecordType>()->getDecl());
1394       if (!HasTrivialDestructorBody(Context, VirtualBase,
1395                                     MostDerivedClassDecl))
1396         return false;
1397     }
1398   }
1399 
1400   return true;
1401 }
1402 
1403 static bool
1404 FieldHasTrivialDestructorBody(ASTContext &Context,
1405                                           const FieldDecl *Field)
1406 {
1407   QualType FieldBaseElementType = Context.getBaseElementType(Field->getType());
1408 
1409   const RecordType *RT = FieldBaseElementType->getAs<RecordType>();
1410   if (!RT)
1411     return true;
1412 
1413   CXXRecordDecl *FieldClassDecl = cast<CXXRecordDecl>(RT->getDecl());
1414 
1415   // The destructor for an implicit anonymous union member is never invoked.
1416   if (FieldClassDecl->isUnion() && FieldClassDecl->isAnonymousStructOrUnion())
1417     return false;
1418 
1419   return HasTrivialDestructorBody(Context, FieldClassDecl, FieldClassDecl);
1420 }
1421 
1422 /// CanSkipVTablePointerInitialization - Check whether we need to initialize
1423 /// any vtable pointers before calling this destructor.
1424 static bool CanSkipVTablePointerInitialization(CodeGenFunction &CGF,
1425                                                const CXXDestructorDecl *Dtor) {
1426   const CXXRecordDecl *ClassDecl = Dtor->getParent();
1427   if (!ClassDecl->isDynamicClass())
1428     return true;
1429 
1430   if (!Dtor->hasTrivialBody())
1431     return false;
1432 
1433   // Check the fields.
1434   for (const auto *Field : ClassDecl->fields())
1435     if (!FieldHasTrivialDestructorBody(CGF.getContext(), Field))
1436       return false;
1437 
1438   return true;
1439 }
1440 
1441 /// EmitDestructorBody - Emits the body of the current destructor.
1442 void CodeGenFunction::EmitDestructorBody(FunctionArgList &Args) {
1443   const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CurGD.getDecl());
1444   CXXDtorType DtorType = CurGD.getDtorType();
1445 
1446   // For an abstract class, non-base destructors are never used (and can't
1447   // be emitted in general, because vbase dtors may not have been validated
1448   // by Sema), but the Itanium ABI doesn't make them optional and Clang may
1449   // in fact emit references to them from other compilations, so emit them
1450   // as functions containing a trap instruction.
1451   if (DtorType != Dtor_Base && Dtor->getParent()->isAbstract()) {
1452     llvm::CallInst *TrapCall = EmitTrapCall(llvm::Intrinsic::trap);
1453     TrapCall->setDoesNotReturn();
1454     TrapCall->setDoesNotThrow();
1455     Builder.CreateUnreachable();
1456     Builder.ClearInsertionPoint();
1457     return;
1458   }
1459 
1460   Stmt *Body = Dtor->getBody();
1461   if (Body)
1462     incrementProfileCounter(Body);
1463 
1464   // The call to operator delete in a deleting destructor happens
1465   // outside of the function-try-block, which means it's always
1466   // possible to delegate the destructor body to the complete
1467   // destructor.  Do so.
1468   if (DtorType == Dtor_Deleting) {
1469     RunCleanupsScope DtorEpilogue(*this);
1470     EnterDtorCleanups(Dtor, Dtor_Deleting);
1471     if (HaveInsertPoint()) {
1472       QualType ThisTy = Dtor->getThisObjectType();
1473       EmitCXXDestructorCall(Dtor, Dtor_Complete, /*ForVirtualBase=*/false,
1474                             /*Delegating=*/false, LoadCXXThisAddress(), ThisTy);
1475     }
1476     return;
1477   }
1478 
1479   // If the body is a function-try-block, enter the try before
1480   // anything else.
1481   bool isTryBody = (Body && isa<CXXTryStmt>(Body));
1482   if (isTryBody)
1483     EnterCXXTryStmt(*cast<CXXTryStmt>(Body), true);
1484   EmitAsanPrologueOrEpilogue(false);
1485 
1486   // Enter the epilogue cleanups.
1487   RunCleanupsScope DtorEpilogue(*this);
1488 
1489   // If this is the complete variant, just invoke the base variant;
1490   // the epilogue will destruct the virtual bases.  But we can't do
1491   // this optimization if the body is a function-try-block, because
1492   // we'd introduce *two* handler blocks.  In the Microsoft ABI, we
1493   // always delegate because we might not have a definition in this TU.
1494   switch (DtorType) {
1495   case Dtor_Comdat: llvm_unreachable("not expecting a COMDAT");
1496   case Dtor_Deleting: llvm_unreachable("already handled deleting case");
1497 
1498   case Dtor_Complete:
1499     assert((Body || getTarget().getCXXABI().isMicrosoft()) &&
1500            "can't emit a dtor without a body for non-Microsoft ABIs");
1501 
1502     // Enter the cleanup scopes for virtual bases.
1503     EnterDtorCleanups(Dtor, Dtor_Complete);
1504 
1505     if (!isTryBody) {
1506       QualType ThisTy = Dtor->getThisObjectType();
1507       EmitCXXDestructorCall(Dtor, Dtor_Base, /*ForVirtualBase=*/false,
1508                             /*Delegating=*/false, LoadCXXThisAddress(), ThisTy);
1509       break;
1510     }
1511 
1512     // Fallthrough: act like we're in the base variant.
1513     LLVM_FALLTHROUGH;
1514 
1515   case Dtor_Base:
1516     assert(Body);
1517 
1518     // Enter the cleanup scopes for fields and non-virtual bases.
1519     EnterDtorCleanups(Dtor, Dtor_Base);
1520 
1521     // Initialize the vtable pointers before entering the body.
1522     if (!CanSkipVTablePointerInitialization(*this, Dtor)) {
1523       // Insert the llvm.launder.invariant.group intrinsic before initializing
1524       // the vptrs to cancel any previous assumptions we might have made.
1525       if (CGM.getCodeGenOpts().StrictVTablePointers &&
1526           CGM.getCodeGenOpts().OptimizationLevel > 0)
1527         CXXThisValue = Builder.CreateLaunderInvariantGroup(LoadCXXThis());
1528       InitializeVTablePointers(Dtor->getParent());
1529     }
1530 
1531     if (isTryBody)
1532       EmitStmt(cast<CXXTryStmt>(Body)->getTryBlock());
1533     else if (Body)
1534       EmitStmt(Body);
1535     else {
1536       assert(Dtor->isImplicit() && "bodyless dtor not implicit");
1537       // nothing to do besides what's in the epilogue
1538     }
1539     // -fapple-kext must inline any call to this dtor into
1540     // the caller's body.
1541     if (getLangOpts().AppleKext)
1542       CurFn->addFnAttr(llvm::Attribute::AlwaysInline);
1543 
1544     break;
1545   }
1546 
1547   // Jump out through the epilogue cleanups.
1548   DtorEpilogue.ForceCleanup();
1549 
1550   // Exit the try if applicable.
1551   if (isTryBody)
1552     ExitCXXTryStmt(*cast<CXXTryStmt>(Body), true);
1553 }
1554 
1555 void CodeGenFunction::emitImplicitAssignmentOperatorBody(FunctionArgList &Args) {
1556   const CXXMethodDecl *AssignOp = cast<CXXMethodDecl>(CurGD.getDecl());
1557   const Stmt *RootS = AssignOp->getBody();
1558   assert(isa<CompoundStmt>(RootS) &&
1559          "Body of an implicit assignment operator should be compound stmt.");
1560   const CompoundStmt *RootCS = cast<CompoundStmt>(RootS);
1561 
1562   LexicalScope Scope(*this, RootCS->getSourceRange());
1563 
1564   incrementProfileCounter(RootCS);
1565   AssignmentMemcpyizer AM(*this, AssignOp, Args);
1566   for (auto *I : RootCS->body())
1567     AM.emitAssignment(I);
1568   AM.finish();
1569 }
1570 
1571 namespace {
1572   llvm::Value *LoadThisForDtorDelete(CodeGenFunction &CGF,
1573                                      const CXXDestructorDecl *DD) {
1574     if (Expr *ThisArg = DD->getOperatorDeleteThisArg())
1575       return CGF.EmitScalarExpr(ThisArg);
1576     return CGF.LoadCXXThis();
1577   }
1578 
1579   /// Call the operator delete associated with the current destructor.
1580   struct CallDtorDelete final : EHScopeStack::Cleanup {
1581     CallDtorDelete() {}
1582 
1583     void Emit(CodeGenFunction &CGF, Flags flags) override {
1584       const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CGF.CurCodeDecl);
1585       const CXXRecordDecl *ClassDecl = Dtor->getParent();
1586       CGF.EmitDeleteCall(Dtor->getOperatorDelete(),
1587                          LoadThisForDtorDelete(CGF, Dtor),
1588                          CGF.getContext().getTagDeclType(ClassDecl));
1589     }
1590   };
1591 
1592   void EmitConditionalDtorDeleteCall(CodeGenFunction &CGF,
1593                                      llvm::Value *ShouldDeleteCondition,
1594                                      bool ReturnAfterDelete) {
1595     llvm::BasicBlock *callDeleteBB = CGF.createBasicBlock("dtor.call_delete");
1596     llvm::BasicBlock *continueBB = CGF.createBasicBlock("dtor.continue");
1597     llvm::Value *ShouldCallDelete
1598       = CGF.Builder.CreateIsNull(ShouldDeleteCondition);
1599     CGF.Builder.CreateCondBr(ShouldCallDelete, continueBB, callDeleteBB);
1600 
1601     CGF.EmitBlock(callDeleteBB);
1602     const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CGF.CurCodeDecl);
1603     const CXXRecordDecl *ClassDecl = Dtor->getParent();
1604     CGF.EmitDeleteCall(Dtor->getOperatorDelete(),
1605                        LoadThisForDtorDelete(CGF, Dtor),
1606                        CGF.getContext().getTagDeclType(ClassDecl));
1607     assert(Dtor->getOperatorDelete()->isDestroyingOperatorDelete() ==
1608                ReturnAfterDelete &&
1609            "unexpected value for ReturnAfterDelete");
1610     if (ReturnAfterDelete)
1611       CGF.EmitBranchThroughCleanup(CGF.ReturnBlock);
1612     else
1613       CGF.Builder.CreateBr(continueBB);
1614 
1615     CGF.EmitBlock(continueBB);
1616   }
1617 
1618   struct CallDtorDeleteConditional final : EHScopeStack::Cleanup {
1619     llvm::Value *ShouldDeleteCondition;
1620 
1621   public:
1622     CallDtorDeleteConditional(llvm::Value *ShouldDeleteCondition)
1623         : ShouldDeleteCondition(ShouldDeleteCondition) {
1624       assert(ShouldDeleteCondition != nullptr);
1625     }
1626 
1627     void Emit(CodeGenFunction &CGF, Flags flags) override {
1628       EmitConditionalDtorDeleteCall(CGF, ShouldDeleteCondition,
1629                                     /*ReturnAfterDelete*/false);
1630     }
1631   };
1632 
1633   class DestroyField  final : public EHScopeStack::Cleanup {
1634     const FieldDecl *field;
1635     CodeGenFunction::Destroyer *destroyer;
1636     bool useEHCleanupForArray;
1637 
1638   public:
1639     DestroyField(const FieldDecl *field, CodeGenFunction::Destroyer *destroyer,
1640                  bool useEHCleanupForArray)
1641         : field(field), destroyer(destroyer),
1642           useEHCleanupForArray(useEHCleanupForArray) {}
1643 
1644     void Emit(CodeGenFunction &CGF, Flags flags) override {
1645       // Find the address of the field.
1646       Address thisValue = CGF.LoadCXXThisAddress();
1647       QualType RecordTy = CGF.getContext().getTagDeclType(field->getParent());
1648       LValue ThisLV = CGF.MakeAddrLValue(thisValue, RecordTy);
1649       LValue LV = CGF.EmitLValueForField(ThisLV, field);
1650       assert(LV.isSimple());
1651 
1652       CGF.emitDestroy(LV.getAddress(CGF), field->getType(), destroyer,
1653                       flags.isForNormalCleanup() && useEHCleanupForArray);
1654     }
1655   };
1656 
1657  static void EmitSanitizerDtorCallback(CodeGenFunction &CGF, llvm::Value *Ptr,
1658              CharUnits::QuantityType PoisonSize) {
1659    CodeGenFunction::SanitizerScope SanScope(&CGF);
1660    // Pass in void pointer and size of region as arguments to runtime
1661    // function
1662    llvm::Value *Args[] = {CGF.Builder.CreateBitCast(Ptr, CGF.VoidPtrTy),
1663                           llvm::ConstantInt::get(CGF.SizeTy, PoisonSize)};
1664 
1665    llvm::Type *ArgTypes[] = {CGF.VoidPtrTy, CGF.SizeTy};
1666 
1667    llvm::FunctionType *FnType =
1668        llvm::FunctionType::get(CGF.VoidTy, ArgTypes, false);
1669    llvm::FunctionCallee Fn =
1670        CGF.CGM.CreateRuntimeFunction(FnType, "__sanitizer_dtor_callback");
1671    CGF.EmitNounwindRuntimeCall(Fn, Args);
1672  }
1673 
1674   class SanitizeDtorMembers final : public EHScopeStack::Cleanup {
1675     const CXXDestructorDecl *Dtor;
1676 
1677   public:
1678     SanitizeDtorMembers(const CXXDestructorDecl *Dtor) : Dtor(Dtor) {}
1679 
1680     // Generate function call for handling object poisoning.
1681     // Disables tail call elimination, to prevent the current stack frame
1682     // from disappearing from the stack trace.
1683     void Emit(CodeGenFunction &CGF, Flags flags) override {
1684       const ASTRecordLayout &Layout =
1685           CGF.getContext().getASTRecordLayout(Dtor->getParent());
1686 
1687       // Nothing to poison.
1688       if (Layout.getFieldCount() == 0)
1689         return;
1690 
1691       // Prevent the current stack frame from disappearing from the stack trace.
1692       CGF.CurFn->addFnAttr("disable-tail-calls", "true");
1693 
1694       // Construct pointer to region to begin poisoning, and calculate poison
1695       // size, so that only members declared in this class are poisoned.
1696       ASTContext &Context = CGF.getContext();
1697 
1698       const RecordDecl *Decl = Dtor->getParent();
1699       auto Fields = Decl->fields();
1700       auto IsTrivial = [&](const FieldDecl *F) {
1701         return FieldHasTrivialDestructorBody(Context, F);
1702       };
1703 
1704       auto IsZeroSize = [&](const FieldDecl *F) {
1705         return F->isZeroSize(Context);
1706       };
1707 
1708       // Poison blocks of fields with trivial destructors making sure that block
1709       // begin and end do not point to zero-sized fields. They don't have
1710       // correct offsets so can't be used to calculate poisoning range.
1711       for (auto It = Fields.begin(); It != Fields.end();) {
1712         It = std::find_if(It, Fields.end(), [&](const FieldDecl *F) {
1713           return IsTrivial(F) && !IsZeroSize(F);
1714         });
1715         if (It == Fields.end())
1716           break;
1717         auto Start = It++;
1718         It = std::find_if(It, Fields.end(), [&](const FieldDecl *F) {
1719           return !IsTrivial(F) && !IsZeroSize(F);
1720         });
1721 
1722         PoisonMembers(CGF, (*Start)->getFieldIndex(),
1723                       It == Fields.end() ? -1 : (*It)->getFieldIndex());
1724       }
1725     }
1726 
1727   private:
1728     /// \param layoutStartOffset index of the ASTRecordLayout field to
1729     ///     start poisoning (inclusive)
1730     /// \param layoutEndOffset index of the ASTRecordLayout field to
1731     ///     end poisoning (exclusive)
1732     void PoisonMembers(CodeGenFunction &CGF, unsigned layoutStartOffset,
1733                        unsigned layoutEndOffset) {
1734       ASTContext &Context = CGF.getContext();
1735       const ASTRecordLayout &Layout =
1736           Context.getASTRecordLayout(Dtor->getParent());
1737 
1738       // It's a first trivia field so it should be at the begining of char,
1739       // still round up start offset just in case.
1740       CharUnits PoisonStart =
1741           Context.toCharUnitsFromBits(Layout.getFieldOffset(layoutStartOffset) +
1742                                       Context.getCharWidth() - 1);
1743       llvm::ConstantInt *OffsetSizePtr =
1744           llvm::ConstantInt::get(CGF.SizeTy, PoisonStart.getQuantity());
1745 
1746       llvm::Value *OffsetPtr = CGF.Builder.CreateGEP(
1747           CGF.Builder.CreateBitCast(CGF.LoadCXXThis(), CGF.Int8PtrTy),
1748           OffsetSizePtr);
1749 
1750       CharUnits PoisonEnd;
1751       if (layoutEndOffset >= Layout.getFieldCount()) {
1752         PoisonEnd = Layout.getNonVirtualSize();
1753       } else {
1754         PoisonEnd =
1755             Context.toCharUnitsFromBits(Layout.getFieldOffset(layoutEndOffset));
1756       }
1757       CharUnits PoisonSize = PoisonEnd - PoisonStart;
1758       if (!PoisonSize.isPositive())
1759         return;
1760 
1761       EmitSanitizerDtorCallback(CGF, OffsetPtr, PoisonSize.getQuantity());
1762     }
1763   };
1764 
1765  class SanitizeDtorVTable final : public EHScopeStack::Cleanup {
1766     const CXXDestructorDecl *Dtor;
1767 
1768   public:
1769     SanitizeDtorVTable(const CXXDestructorDecl *Dtor) : Dtor(Dtor) {}
1770 
1771     // Generate function call for handling vtable pointer poisoning.
1772     void Emit(CodeGenFunction &CGF, Flags flags) override {
1773       assert(Dtor->getParent()->isDynamicClass());
1774       (void)Dtor;
1775       ASTContext &Context = CGF.getContext();
1776       // Poison vtable and vtable ptr if they exist for this class.
1777       llvm::Value *VTablePtr = CGF.LoadCXXThis();
1778 
1779       CharUnits::QuantityType PoisonSize =
1780           Context.toCharUnitsFromBits(CGF.PointerWidthInBits).getQuantity();
1781       // Pass in void pointer and size of region as arguments to runtime
1782       // function
1783       EmitSanitizerDtorCallback(CGF, VTablePtr, PoisonSize);
1784     }
1785  };
1786 } // end anonymous namespace
1787 
1788 /// Emit all code that comes at the end of class's
1789 /// destructor. This is to call destructors on members and base classes
1790 /// in reverse order of their construction.
1791 ///
1792 /// For a deleting destructor, this also handles the case where a destroying
1793 /// operator delete completely overrides the definition.
1794 void CodeGenFunction::EnterDtorCleanups(const CXXDestructorDecl *DD,
1795                                         CXXDtorType DtorType) {
1796   assert((!DD->isTrivial() || DD->hasAttr<DLLExportAttr>()) &&
1797          "Should not emit dtor epilogue for non-exported trivial dtor!");
1798 
1799   // The deleting-destructor phase just needs to call the appropriate
1800   // operator delete that Sema picked up.
1801   if (DtorType == Dtor_Deleting) {
1802     assert(DD->getOperatorDelete() &&
1803            "operator delete missing - EnterDtorCleanups");
1804     if (CXXStructorImplicitParamValue) {
1805       // If there is an implicit param to the deleting dtor, it's a boolean
1806       // telling whether this is a deleting destructor.
1807       if (DD->getOperatorDelete()->isDestroyingOperatorDelete())
1808         EmitConditionalDtorDeleteCall(*this, CXXStructorImplicitParamValue,
1809                                       /*ReturnAfterDelete*/true);
1810       else
1811         EHStack.pushCleanup<CallDtorDeleteConditional>(
1812             NormalAndEHCleanup, CXXStructorImplicitParamValue);
1813     } else {
1814       if (DD->getOperatorDelete()->isDestroyingOperatorDelete()) {
1815         const CXXRecordDecl *ClassDecl = DD->getParent();
1816         EmitDeleteCall(DD->getOperatorDelete(),
1817                        LoadThisForDtorDelete(*this, DD),
1818                        getContext().getTagDeclType(ClassDecl));
1819         EmitBranchThroughCleanup(ReturnBlock);
1820       } else {
1821         EHStack.pushCleanup<CallDtorDelete>(NormalAndEHCleanup);
1822       }
1823     }
1824     return;
1825   }
1826 
1827   const CXXRecordDecl *ClassDecl = DD->getParent();
1828 
1829   // Unions have no bases and do not call field destructors.
1830   if (ClassDecl->isUnion())
1831     return;
1832 
1833   // The complete-destructor phase just destructs all the virtual bases.
1834   if (DtorType == Dtor_Complete) {
1835     // Poison the vtable pointer such that access after the base
1836     // and member destructors are invoked is invalid.
1837     if (CGM.getCodeGenOpts().SanitizeMemoryUseAfterDtor &&
1838         SanOpts.has(SanitizerKind::Memory) && ClassDecl->getNumVBases() &&
1839         ClassDecl->isPolymorphic())
1840       EHStack.pushCleanup<SanitizeDtorVTable>(NormalAndEHCleanup, DD);
1841 
1842     // We push them in the forward order so that they'll be popped in
1843     // the reverse order.
1844     for (const auto &Base : ClassDecl->vbases()) {
1845       auto *BaseClassDecl =
1846           cast<CXXRecordDecl>(Base.getType()->castAs<RecordType>()->getDecl());
1847 
1848       // Ignore trivial destructors.
1849       if (BaseClassDecl->hasTrivialDestructor())
1850         continue;
1851 
1852       EHStack.pushCleanup<CallBaseDtor>(NormalAndEHCleanup,
1853                                         BaseClassDecl,
1854                                         /*BaseIsVirtual*/ true);
1855     }
1856 
1857     return;
1858   }
1859 
1860   assert(DtorType == Dtor_Base);
1861   // Poison the vtable pointer if it has no virtual bases, but inherits
1862   // virtual functions.
1863   if (CGM.getCodeGenOpts().SanitizeMemoryUseAfterDtor &&
1864       SanOpts.has(SanitizerKind::Memory) && !ClassDecl->getNumVBases() &&
1865       ClassDecl->isPolymorphic())
1866     EHStack.pushCleanup<SanitizeDtorVTable>(NormalAndEHCleanup, DD);
1867 
1868   // Destroy non-virtual bases.
1869   for (const auto &Base : ClassDecl->bases()) {
1870     // Ignore virtual bases.
1871     if (Base.isVirtual())
1872       continue;
1873 
1874     CXXRecordDecl *BaseClassDecl = Base.getType()->getAsCXXRecordDecl();
1875 
1876     // Ignore trivial destructors.
1877     if (BaseClassDecl->hasTrivialDestructor())
1878       continue;
1879 
1880     EHStack.pushCleanup<CallBaseDtor>(NormalAndEHCleanup,
1881                                       BaseClassDecl,
1882                                       /*BaseIsVirtual*/ false);
1883   }
1884 
1885   // Poison fields such that access after their destructors are
1886   // invoked, and before the base class destructor runs, is invalid.
1887   if (CGM.getCodeGenOpts().SanitizeMemoryUseAfterDtor &&
1888       SanOpts.has(SanitizerKind::Memory))
1889     EHStack.pushCleanup<SanitizeDtorMembers>(NormalAndEHCleanup, DD);
1890 
1891   // Destroy direct fields.
1892   for (const auto *Field : ClassDecl->fields()) {
1893     QualType type = Field->getType();
1894     QualType::DestructionKind dtorKind = type.isDestructedType();
1895     if (!dtorKind) continue;
1896 
1897     // Anonymous union members do not have their destructors called.
1898     const RecordType *RT = type->getAsUnionType();
1899     if (RT && RT->getDecl()->isAnonymousStructOrUnion()) continue;
1900 
1901     CleanupKind cleanupKind = getCleanupKind(dtorKind);
1902     EHStack.pushCleanup<DestroyField>(cleanupKind, Field,
1903                                       getDestroyer(dtorKind),
1904                                       cleanupKind & EHCleanup);
1905   }
1906 }
1907 
1908 /// EmitCXXAggrConstructorCall - Emit a loop to call a particular
1909 /// constructor for each of several members of an array.
1910 ///
1911 /// \param ctor the constructor to call for each element
1912 /// \param arrayType the type of the array to initialize
1913 /// \param arrayBegin an arrayType*
1914 /// \param zeroInitialize true if each element should be
1915 ///   zero-initialized before it is constructed
1916 void CodeGenFunction::EmitCXXAggrConstructorCall(
1917     const CXXConstructorDecl *ctor, const ArrayType *arrayType,
1918     Address arrayBegin, const CXXConstructExpr *E, bool NewPointerIsChecked,
1919     bool zeroInitialize) {
1920   QualType elementType;
1921   llvm::Value *numElements =
1922     emitArrayLength(arrayType, elementType, arrayBegin);
1923 
1924   EmitCXXAggrConstructorCall(ctor, numElements, arrayBegin, E,
1925                              NewPointerIsChecked, zeroInitialize);
1926 }
1927 
1928 /// EmitCXXAggrConstructorCall - Emit a loop to call a particular
1929 /// constructor for each of several members of an array.
1930 ///
1931 /// \param ctor the constructor to call for each element
1932 /// \param numElements the number of elements in the array;
1933 ///   may be zero
1934 /// \param arrayBase a T*, where T is the type constructed by ctor
1935 /// \param zeroInitialize true if each element should be
1936 ///   zero-initialized before it is constructed
1937 void CodeGenFunction::EmitCXXAggrConstructorCall(const CXXConstructorDecl *ctor,
1938                                                  llvm::Value *numElements,
1939                                                  Address arrayBase,
1940                                                  const CXXConstructExpr *E,
1941                                                  bool NewPointerIsChecked,
1942                                                  bool zeroInitialize) {
1943   // It's legal for numElements to be zero.  This can happen both
1944   // dynamically, because x can be zero in 'new A[x]', and statically,
1945   // because of GCC extensions that permit zero-length arrays.  There
1946   // are probably legitimate places where we could assume that this
1947   // doesn't happen, but it's not clear that it's worth it.
1948   llvm::BranchInst *zeroCheckBranch = nullptr;
1949 
1950   // Optimize for a constant count.
1951   llvm::ConstantInt *constantCount
1952     = dyn_cast<llvm::ConstantInt>(numElements);
1953   if (constantCount) {
1954     // Just skip out if the constant count is zero.
1955     if (constantCount->isZero()) return;
1956 
1957   // Otherwise, emit the check.
1958   } else {
1959     llvm::BasicBlock *loopBB = createBasicBlock("new.ctorloop");
1960     llvm::Value *iszero = Builder.CreateIsNull(numElements, "isempty");
1961     zeroCheckBranch = Builder.CreateCondBr(iszero, loopBB, loopBB);
1962     EmitBlock(loopBB);
1963   }
1964 
1965   // Find the end of the array.
1966   llvm::Value *arrayBegin = arrayBase.getPointer();
1967   llvm::Value *arrayEnd = Builder.CreateInBoundsGEP(arrayBegin, numElements,
1968                                                     "arrayctor.end");
1969 
1970   // Enter the loop, setting up a phi for the current location to initialize.
1971   llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
1972   llvm::BasicBlock *loopBB = createBasicBlock("arrayctor.loop");
1973   EmitBlock(loopBB);
1974   llvm::PHINode *cur = Builder.CreatePHI(arrayBegin->getType(), 2,
1975                                          "arrayctor.cur");
1976   cur->addIncoming(arrayBegin, entryBB);
1977 
1978   // Inside the loop body, emit the constructor call on the array element.
1979 
1980   // The alignment of the base, adjusted by the size of a single element,
1981   // provides a conservative estimate of the alignment of every element.
1982   // (This assumes we never start tracking offsetted alignments.)
1983   //
1984   // Note that these are complete objects and so we don't need to
1985   // use the non-virtual size or alignment.
1986   QualType type = getContext().getTypeDeclType(ctor->getParent());
1987   CharUnits eltAlignment =
1988     arrayBase.getAlignment()
1989              .alignmentOfArrayElement(getContext().getTypeSizeInChars(type));
1990   Address curAddr = Address(cur, eltAlignment);
1991 
1992   // Zero initialize the storage, if requested.
1993   if (zeroInitialize)
1994     EmitNullInitialization(curAddr, type);
1995 
1996   // C++ [class.temporary]p4:
1997   // There are two contexts in which temporaries are destroyed at a different
1998   // point than the end of the full-expression. The first context is when a
1999   // default constructor is called to initialize an element of an array.
2000   // If the constructor has one or more default arguments, the destruction of
2001   // every temporary created in a default argument expression is sequenced
2002   // before the construction of the next array element, if any.
2003 
2004   {
2005     RunCleanupsScope Scope(*this);
2006 
2007     // Evaluate the constructor and its arguments in a regular
2008     // partial-destroy cleanup.
2009     if (getLangOpts().Exceptions &&
2010         !ctor->getParent()->hasTrivialDestructor()) {
2011       Destroyer *destroyer = destroyCXXObject;
2012       pushRegularPartialArrayCleanup(arrayBegin, cur, type, eltAlignment,
2013                                      *destroyer);
2014     }
2015     auto currAVS = AggValueSlot::forAddr(
2016         curAddr, type.getQualifiers(), AggValueSlot::IsDestructed,
2017         AggValueSlot::DoesNotNeedGCBarriers, AggValueSlot::IsNotAliased,
2018         AggValueSlot::DoesNotOverlap, AggValueSlot::IsNotZeroed,
2019         NewPointerIsChecked ? AggValueSlot::IsSanitizerChecked
2020                             : AggValueSlot::IsNotSanitizerChecked);
2021     EmitCXXConstructorCall(ctor, Ctor_Complete, /*ForVirtualBase=*/false,
2022                            /*Delegating=*/false, currAVS, E);
2023   }
2024 
2025   // Go to the next element.
2026   llvm::Value *next =
2027     Builder.CreateInBoundsGEP(cur, llvm::ConstantInt::get(SizeTy, 1),
2028                               "arrayctor.next");
2029   cur->addIncoming(next, Builder.GetInsertBlock());
2030 
2031   // Check whether that's the end of the loop.
2032   llvm::Value *done = Builder.CreateICmpEQ(next, arrayEnd, "arrayctor.done");
2033   llvm::BasicBlock *contBB = createBasicBlock("arrayctor.cont");
2034   Builder.CreateCondBr(done, contBB, loopBB);
2035 
2036   // Patch the earlier check to skip over the loop.
2037   if (zeroCheckBranch) zeroCheckBranch->setSuccessor(0, contBB);
2038 
2039   EmitBlock(contBB);
2040 }
2041 
2042 void CodeGenFunction::destroyCXXObject(CodeGenFunction &CGF,
2043                                        Address addr,
2044                                        QualType type) {
2045   const RecordType *rtype = type->castAs<RecordType>();
2046   const CXXRecordDecl *record = cast<CXXRecordDecl>(rtype->getDecl());
2047   const CXXDestructorDecl *dtor = record->getDestructor();
2048   assert(!dtor->isTrivial());
2049   CGF.EmitCXXDestructorCall(dtor, Dtor_Complete, /*for vbase*/ false,
2050                             /*Delegating=*/false, addr, type);
2051 }
2052 
2053 void CodeGenFunction::EmitCXXConstructorCall(const CXXConstructorDecl *D,
2054                                              CXXCtorType Type,
2055                                              bool ForVirtualBase,
2056                                              bool Delegating,
2057                                              AggValueSlot ThisAVS,
2058                                              const CXXConstructExpr *E) {
2059   CallArgList Args;
2060   Address This = ThisAVS.getAddress();
2061   LangAS SlotAS = ThisAVS.getQualifiers().getAddressSpace();
2062   QualType ThisType = D->getThisType();
2063   LangAS ThisAS = ThisType.getTypePtr()->getPointeeType().getAddressSpace();
2064   llvm::Value *ThisPtr = This.getPointer();
2065 
2066   if (SlotAS != ThisAS) {
2067     unsigned TargetThisAS = getContext().getTargetAddressSpace(ThisAS);
2068     llvm::Type *NewType =
2069         ThisPtr->getType()->getPointerElementType()->getPointerTo(TargetThisAS);
2070     ThisPtr = getTargetHooks().performAddrSpaceCast(*this, This.getPointer(),
2071                                                     ThisAS, SlotAS, NewType);
2072   }
2073 
2074   // Push the this ptr.
2075   Args.add(RValue::get(ThisPtr), D->getThisType());
2076 
2077   // If this is a trivial constructor, emit a memcpy now before we lose
2078   // the alignment information on the argument.
2079   // FIXME: It would be better to preserve alignment information into CallArg.
2080   if (isMemcpyEquivalentSpecialMember(D)) {
2081     assert(E->getNumArgs() == 1 && "unexpected argcount for trivial ctor");
2082 
2083     const Expr *Arg = E->getArg(0);
2084     LValue Src = EmitLValue(Arg);
2085     QualType DestTy = getContext().getTypeDeclType(D->getParent());
2086     LValue Dest = MakeAddrLValue(This, DestTy);
2087     EmitAggregateCopyCtor(Dest, Src, ThisAVS.mayOverlap());
2088     return;
2089   }
2090 
2091   // Add the rest of the user-supplied arguments.
2092   const FunctionProtoType *FPT = D->getType()->castAs<FunctionProtoType>();
2093   EvaluationOrder Order = E->isListInitialization()
2094                               ? EvaluationOrder::ForceLeftToRight
2095                               : EvaluationOrder::Default;
2096   EmitCallArgs(Args, FPT, E->arguments(), E->getConstructor(),
2097                /*ParamsToSkip*/ 0, Order);
2098 
2099   EmitCXXConstructorCall(D, Type, ForVirtualBase, Delegating, This, Args,
2100                          ThisAVS.mayOverlap(), E->getExprLoc(),
2101                          ThisAVS.isSanitizerChecked());
2102 }
2103 
2104 static bool canEmitDelegateCallArgs(CodeGenFunction &CGF,
2105                                     const CXXConstructorDecl *Ctor,
2106                                     CXXCtorType Type, CallArgList &Args) {
2107   // We can't forward a variadic call.
2108   if (Ctor->isVariadic())
2109     return false;
2110 
2111   if (CGF.getTarget().getCXXABI().areArgsDestroyedLeftToRightInCallee()) {
2112     // If the parameters are callee-cleanup, it's not safe to forward.
2113     for (auto *P : Ctor->parameters())
2114       if (P->needsDestruction(CGF.getContext()))
2115         return false;
2116 
2117     // Likewise if they're inalloca.
2118     const CGFunctionInfo &Info =
2119         CGF.CGM.getTypes().arrangeCXXConstructorCall(Args, Ctor, Type, 0, 0);
2120     if (Info.usesInAlloca())
2121       return false;
2122   }
2123 
2124   // Anything else should be OK.
2125   return true;
2126 }
2127 
2128 void CodeGenFunction::EmitCXXConstructorCall(const CXXConstructorDecl *D,
2129                                              CXXCtorType Type,
2130                                              bool ForVirtualBase,
2131                                              bool Delegating,
2132                                              Address This,
2133                                              CallArgList &Args,
2134                                              AggValueSlot::Overlap_t Overlap,
2135                                              SourceLocation Loc,
2136                                              bool NewPointerIsChecked) {
2137   const CXXRecordDecl *ClassDecl = D->getParent();
2138 
2139   if (!NewPointerIsChecked)
2140     EmitTypeCheck(CodeGenFunction::TCK_ConstructorCall, Loc, This.getPointer(),
2141                   getContext().getRecordType(ClassDecl), CharUnits::Zero());
2142 
2143   if (D->isTrivial() && D->isDefaultConstructor()) {
2144     assert(Args.size() == 1 && "trivial default ctor with args");
2145     return;
2146   }
2147 
2148   // If this is a trivial constructor, just emit what's needed. If this is a
2149   // union copy constructor, we must emit a memcpy, because the AST does not
2150   // model that copy.
2151   if (isMemcpyEquivalentSpecialMember(D)) {
2152     assert(Args.size() == 2 && "unexpected argcount for trivial ctor");
2153 
2154     QualType SrcTy = D->getParamDecl(0)->getType().getNonReferenceType();
2155     Address Src(Args[1].getRValue(*this).getScalarVal(),
2156                 CGM.getNaturalTypeAlignment(SrcTy));
2157     LValue SrcLVal = MakeAddrLValue(Src, SrcTy);
2158     QualType DestTy = getContext().getTypeDeclType(ClassDecl);
2159     LValue DestLVal = MakeAddrLValue(This, DestTy);
2160     EmitAggregateCopyCtor(DestLVal, SrcLVal, Overlap);
2161     return;
2162   }
2163 
2164   bool PassPrototypeArgs = true;
2165   // Check whether we can actually emit the constructor before trying to do so.
2166   if (auto Inherited = D->getInheritedConstructor()) {
2167     PassPrototypeArgs = getTypes().inheritingCtorHasParams(Inherited, Type);
2168     if (PassPrototypeArgs && !canEmitDelegateCallArgs(*this, D, Type, Args)) {
2169       EmitInlinedInheritingCXXConstructorCall(D, Type, ForVirtualBase,
2170                                               Delegating, Args);
2171       return;
2172     }
2173   }
2174 
2175   // Insert any ABI-specific implicit constructor arguments.
2176   CGCXXABI::AddedStructorArgCounts ExtraArgs =
2177       CGM.getCXXABI().addImplicitConstructorArgs(*this, D, Type, ForVirtualBase,
2178                                                  Delegating, Args);
2179 
2180   // Emit the call.
2181   llvm::Constant *CalleePtr = CGM.getAddrOfCXXStructor(GlobalDecl(D, Type));
2182   const CGFunctionInfo &Info = CGM.getTypes().arrangeCXXConstructorCall(
2183       Args, D, Type, ExtraArgs.Prefix, ExtraArgs.Suffix, PassPrototypeArgs);
2184   CGCallee Callee = CGCallee::forDirect(CalleePtr, GlobalDecl(D, Type));
2185   EmitCall(Info, Callee, ReturnValueSlot(), Args, nullptr, Loc);
2186 
2187   // Generate vtable assumptions if we're constructing a complete object
2188   // with a vtable.  We don't do this for base subobjects for two reasons:
2189   // first, it's incorrect for classes with virtual bases, and second, we're
2190   // about to overwrite the vptrs anyway.
2191   // We also have to make sure if we can refer to vtable:
2192   // - Otherwise we can refer to vtable if it's safe to speculatively emit.
2193   // FIXME: If vtable is used by ctor/dtor, or if vtable is external and we are
2194   // sure that definition of vtable is not hidden,
2195   // then we are always safe to refer to it.
2196   // FIXME: It looks like InstCombine is very inefficient on dealing with
2197   // assumes. Make assumption loads require -fstrict-vtable-pointers temporarily.
2198   if (CGM.getCodeGenOpts().OptimizationLevel > 0 &&
2199       ClassDecl->isDynamicClass() && Type != Ctor_Base &&
2200       CGM.getCXXABI().canSpeculativelyEmitVTable(ClassDecl) &&
2201       CGM.getCodeGenOpts().StrictVTablePointers)
2202     EmitVTableAssumptionLoads(ClassDecl, This);
2203 }
2204 
2205 void CodeGenFunction::EmitInheritedCXXConstructorCall(
2206     const CXXConstructorDecl *D, bool ForVirtualBase, Address This,
2207     bool InheritedFromVBase, const CXXInheritedCtorInitExpr *E) {
2208   CallArgList Args;
2209   CallArg ThisArg(RValue::get(This.getPointer()), D->getThisType());
2210 
2211   // Forward the parameters.
2212   if (InheritedFromVBase &&
2213       CGM.getTarget().getCXXABI().hasConstructorVariants()) {
2214     // Nothing to do; this construction is not responsible for constructing
2215     // the base class containing the inherited constructor.
2216     // FIXME: Can we just pass undef's for the remaining arguments if we don't
2217     // have constructor variants?
2218     Args.push_back(ThisArg);
2219   } else if (!CXXInheritedCtorInitExprArgs.empty()) {
2220     // The inheriting constructor was inlined; just inject its arguments.
2221     assert(CXXInheritedCtorInitExprArgs.size() >= D->getNumParams() &&
2222            "wrong number of parameters for inherited constructor call");
2223     Args = CXXInheritedCtorInitExprArgs;
2224     Args[0] = ThisArg;
2225   } else {
2226     // The inheriting constructor was not inlined. Emit delegating arguments.
2227     Args.push_back(ThisArg);
2228     const auto *OuterCtor = cast<CXXConstructorDecl>(CurCodeDecl);
2229     assert(OuterCtor->getNumParams() == D->getNumParams());
2230     assert(!OuterCtor->isVariadic() && "should have been inlined");
2231 
2232     for (const auto *Param : OuterCtor->parameters()) {
2233       assert(getContext().hasSameUnqualifiedType(
2234           OuterCtor->getParamDecl(Param->getFunctionScopeIndex())->getType(),
2235           Param->getType()));
2236       EmitDelegateCallArg(Args, Param, E->getLocation());
2237 
2238       // Forward __attribute__(pass_object_size).
2239       if (Param->hasAttr<PassObjectSizeAttr>()) {
2240         auto *POSParam = SizeArguments[Param];
2241         assert(POSParam && "missing pass_object_size value for forwarding");
2242         EmitDelegateCallArg(Args, POSParam, E->getLocation());
2243       }
2244     }
2245   }
2246 
2247   EmitCXXConstructorCall(D, Ctor_Base, ForVirtualBase, /*Delegating*/false,
2248                          This, Args, AggValueSlot::MayOverlap,
2249                          E->getLocation(), /*NewPointerIsChecked*/true);
2250 }
2251 
2252 void CodeGenFunction::EmitInlinedInheritingCXXConstructorCall(
2253     const CXXConstructorDecl *Ctor, CXXCtorType CtorType, bool ForVirtualBase,
2254     bool Delegating, CallArgList &Args) {
2255   GlobalDecl GD(Ctor, CtorType);
2256   InlinedInheritingConstructorScope Scope(*this, GD);
2257   ApplyInlineDebugLocation DebugScope(*this, GD);
2258   RunCleanupsScope RunCleanups(*this);
2259 
2260   // Save the arguments to be passed to the inherited constructor.
2261   CXXInheritedCtorInitExprArgs = Args;
2262 
2263   FunctionArgList Params;
2264   QualType RetType = BuildFunctionArgList(CurGD, Params);
2265   FnRetTy = RetType;
2266 
2267   // Insert any ABI-specific implicit constructor arguments.
2268   CGM.getCXXABI().addImplicitConstructorArgs(*this, Ctor, CtorType,
2269                                              ForVirtualBase, Delegating, Args);
2270 
2271   // Emit a simplified prolog. We only need to emit the implicit params.
2272   assert(Args.size() >= Params.size() && "too few arguments for call");
2273   for (unsigned I = 0, N = Args.size(); I != N; ++I) {
2274     if (I < Params.size() && isa<ImplicitParamDecl>(Params[I])) {
2275       const RValue &RV = Args[I].getRValue(*this);
2276       assert(!RV.isComplex() && "complex indirect params not supported");
2277       ParamValue Val = RV.isScalar()
2278                            ? ParamValue::forDirect(RV.getScalarVal())
2279                            : ParamValue::forIndirect(RV.getAggregateAddress());
2280       EmitParmDecl(*Params[I], Val, I + 1);
2281     }
2282   }
2283 
2284   // Create a return value slot if the ABI implementation wants one.
2285   // FIXME: This is dumb, we should ask the ABI not to try to set the return
2286   // value instead.
2287   if (!RetType->isVoidType())
2288     ReturnValue = CreateIRTemp(RetType, "retval.inhctor");
2289 
2290   CGM.getCXXABI().EmitInstanceFunctionProlog(*this);
2291   CXXThisValue = CXXABIThisValue;
2292 
2293   // Directly emit the constructor initializers.
2294   EmitCtorPrologue(Ctor, CtorType, Params);
2295 }
2296 
2297 void CodeGenFunction::EmitVTableAssumptionLoad(const VPtr &Vptr, Address This) {
2298   llvm::Value *VTableGlobal =
2299       CGM.getCXXABI().getVTableAddressPoint(Vptr.Base, Vptr.VTableClass);
2300   if (!VTableGlobal)
2301     return;
2302 
2303   // We can just use the base offset in the complete class.
2304   CharUnits NonVirtualOffset = Vptr.Base.getBaseOffset();
2305 
2306   if (!NonVirtualOffset.isZero())
2307     This =
2308         ApplyNonVirtualAndVirtualOffset(*this, This, NonVirtualOffset, nullptr,
2309                                         Vptr.VTableClass, Vptr.NearestVBase);
2310 
2311   llvm::Value *VPtrValue =
2312       GetVTablePtr(This, VTableGlobal->getType(), Vptr.VTableClass);
2313   llvm::Value *Cmp =
2314       Builder.CreateICmpEQ(VPtrValue, VTableGlobal, "cmp.vtables");
2315   Builder.CreateAssumption(Cmp);
2316 }
2317 
2318 void CodeGenFunction::EmitVTableAssumptionLoads(const CXXRecordDecl *ClassDecl,
2319                                                 Address This) {
2320   if (CGM.getCXXABI().doStructorsInitializeVPtrs(ClassDecl))
2321     for (const VPtr &Vptr : getVTablePointers(ClassDecl))
2322       EmitVTableAssumptionLoad(Vptr, This);
2323 }
2324 
2325 void
2326 CodeGenFunction::EmitSynthesizedCXXCopyCtorCall(const CXXConstructorDecl *D,
2327                                                 Address This, Address Src,
2328                                                 const CXXConstructExpr *E) {
2329   const FunctionProtoType *FPT = D->getType()->castAs<FunctionProtoType>();
2330 
2331   CallArgList Args;
2332 
2333   // Push the this ptr.
2334   Args.add(RValue::get(This.getPointer()), D->getThisType());
2335 
2336   // Push the src ptr.
2337   QualType QT = *(FPT->param_type_begin());
2338   llvm::Type *t = CGM.getTypes().ConvertType(QT);
2339   Src = Builder.CreateBitCast(Src, t);
2340   Args.add(RValue::get(Src.getPointer()), QT);
2341 
2342   // Skip over first argument (Src).
2343   EmitCallArgs(Args, FPT, drop_begin(E->arguments(), 1), E->getConstructor(),
2344                /*ParamsToSkip*/ 1);
2345 
2346   EmitCXXConstructorCall(D, Ctor_Complete, /*ForVirtualBase*/false,
2347                          /*Delegating*/false, This, Args,
2348                          AggValueSlot::MayOverlap, E->getExprLoc(),
2349                          /*NewPointerIsChecked*/false);
2350 }
2351 
2352 void
2353 CodeGenFunction::EmitDelegateCXXConstructorCall(const CXXConstructorDecl *Ctor,
2354                                                 CXXCtorType CtorType,
2355                                                 const FunctionArgList &Args,
2356                                                 SourceLocation Loc) {
2357   CallArgList DelegateArgs;
2358 
2359   FunctionArgList::const_iterator I = Args.begin(), E = Args.end();
2360   assert(I != E && "no parameters to constructor");
2361 
2362   // this
2363   Address This = LoadCXXThisAddress();
2364   DelegateArgs.add(RValue::get(This.getPointer()), (*I)->getType());
2365   ++I;
2366 
2367   // FIXME: The location of the VTT parameter in the parameter list is
2368   // specific to the Itanium ABI and shouldn't be hardcoded here.
2369   if (CGM.getCXXABI().NeedsVTTParameter(CurGD)) {
2370     assert(I != E && "cannot skip vtt parameter, already done with args");
2371     assert((*I)->getType()->isPointerType() &&
2372            "skipping parameter not of vtt type");
2373     ++I;
2374   }
2375 
2376   // Explicit arguments.
2377   for (; I != E; ++I) {
2378     const VarDecl *param = *I;
2379     // FIXME: per-argument source location
2380     EmitDelegateCallArg(DelegateArgs, param, Loc);
2381   }
2382 
2383   EmitCXXConstructorCall(Ctor, CtorType, /*ForVirtualBase=*/false,
2384                          /*Delegating=*/true, This, DelegateArgs,
2385                          AggValueSlot::MayOverlap, Loc,
2386                          /*NewPointerIsChecked=*/true);
2387 }
2388 
2389 namespace {
2390   struct CallDelegatingCtorDtor final : EHScopeStack::Cleanup {
2391     const CXXDestructorDecl *Dtor;
2392     Address Addr;
2393     CXXDtorType Type;
2394 
2395     CallDelegatingCtorDtor(const CXXDestructorDecl *D, Address Addr,
2396                            CXXDtorType Type)
2397       : Dtor(D), Addr(Addr), Type(Type) {}
2398 
2399     void Emit(CodeGenFunction &CGF, Flags flags) override {
2400       // We are calling the destructor from within the constructor.
2401       // Therefore, "this" should have the expected type.
2402       QualType ThisTy = Dtor->getThisObjectType();
2403       CGF.EmitCXXDestructorCall(Dtor, Type, /*ForVirtualBase=*/false,
2404                                 /*Delegating=*/true, Addr, ThisTy);
2405     }
2406   };
2407 } // end anonymous namespace
2408 
2409 void
2410 CodeGenFunction::EmitDelegatingCXXConstructorCall(const CXXConstructorDecl *Ctor,
2411                                                   const FunctionArgList &Args) {
2412   assert(Ctor->isDelegatingConstructor());
2413 
2414   Address ThisPtr = LoadCXXThisAddress();
2415 
2416   AggValueSlot AggSlot =
2417     AggValueSlot::forAddr(ThisPtr, Qualifiers(),
2418                           AggValueSlot::IsDestructed,
2419                           AggValueSlot::DoesNotNeedGCBarriers,
2420                           AggValueSlot::IsNotAliased,
2421                           AggValueSlot::MayOverlap,
2422                           AggValueSlot::IsNotZeroed,
2423                           // Checks are made by the code that calls constructor.
2424                           AggValueSlot::IsSanitizerChecked);
2425 
2426   EmitAggExpr(Ctor->init_begin()[0]->getInit(), AggSlot);
2427 
2428   const CXXRecordDecl *ClassDecl = Ctor->getParent();
2429   if (CGM.getLangOpts().Exceptions && !ClassDecl->hasTrivialDestructor()) {
2430     CXXDtorType Type =
2431       CurGD.getCtorType() == Ctor_Complete ? Dtor_Complete : Dtor_Base;
2432 
2433     EHStack.pushCleanup<CallDelegatingCtorDtor>(EHCleanup,
2434                                                 ClassDecl->getDestructor(),
2435                                                 ThisPtr, Type);
2436   }
2437 }
2438 
2439 void CodeGenFunction::EmitCXXDestructorCall(const CXXDestructorDecl *DD,
2440                                             CXXDtorType Type,
2441                                             bool ForVirtualBase,
2442                                             bool Delegating, Address This,
2443                                             QualType ThisTy) {
2444   CGM.getCXXABI().EmitDestructorCall(*this, DD, Type, ForVirtualBase,
2445                                      Delegating, This, ThisTy);
2446 }
2447 
2448 namespace {
2449   struct CallLocalDtor final : EHScopeStack::Cleanup {
2450     const CXXDestructorDecl *Dtor;
2451     Address Addr;
2452     QualType Ty;
2453 
2454     CallLocalDtor(const CXXDestructorDecl *D, Address Addr, QualType Ty)
2455         : Dtor(D), Addr(Addr), Ty(Ty) {}
2456 
2457     void Emit(CodeGenFunction &CGF, Flags flags) override {
2458       CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
2459                                 /*ForVirtualBase=*/false,
2460                                 /*Delegating=*/false, Addr, Ty);
2461     }
2462   };
2463 } // end anonymous namespace
2464 
2465 void CodeGenFunction::PushDestructorCleanup(const CXXDestructorDecl *D,
2466                                             QualType T, Address Addr) {
2467   EHStack.pushCleanup<CallLocalDtor>(NormalAndEHCleanup, D, Addr, T);
2468 }
2469 
2470 void CodeGenFunction::PushDestructorCleanup(QualType T, Address Addr) {
2471   CXXRecordDecl *ClassDecl = T->getAsCXXRecordDecl();
2472   if (!ClassDecl) return;
2473   if (ClassDecl->hasTrivialDestructor()) return;
2474 
2475   const CXXDestructorDecl *D = ClassDecl->getDestructor();
2476   assert(D && D->isUsed() && "destructor not marked as used!");
2477   PushDestructorCleanup(D, T, Addr);
2478 }
2479 
2480 void CodeGenFunction::InitializeVTablePointer(const VPtr &Vptr) {
2481   // Compute the address point.
2482   llvm::Value *VTableAddressPoint =
2483       CGM.getCXXABI().getVTableAddressPointInStructor(
2484           *this, Vptr.VTableClass, Vptr.Base, Vptr.NearestVBase);
2485 
2486   if (!VTableAddressPoint)
2487     return;
2488 
2489   // Compute where to store the address point.
2490   llvm::Value *VirtualOffset = nullptr;
2491   CharUnits NonVirtualOffset = CharUnits::Zero();
2492 
2493   if (CGM.getCXXABI().isVirtualOffsetNeededForVTableField(*this, Vptr)) {
2494     // We need to use the virtual base offset offset because the virtual base
2495     // might have a different offset in the most derived class.
2496 
2497     VirtualOffset = CGM.getCXXABI().GetVirtualBaseClassOffset(
2498         *this, LoadCXXThisAddress(), Vptr.VTableClass, Vptr.NearestVBase);
2499     NonVirtualOffset = Vptr.OffsetFromNearestVBase;
2500   } else {
2501     // We can just use the base offset in the complete class.
2502     NonVirtualOffset = Vptr.Base.getBaseOffset();
2503   }
2504 
2505   // Apply the offsets.
2506   Address VTableField = LoadCXXThisAddress();
2507 
2508   if (!NonVirtualOffset.isZero() || VirtualOffset)
2509     VTableField = ApplyNonVirtualAndVirtualOffset(
2510         *this, VTableField, NonVirtualOffset, VirtualOffset, Vptr.VTableClass,
2511         Vptr.NearestVBase);
2512 
2513   // Finally, store the address point. Use the same LLVM types as the field to
2514   // support optimization.
2515   unsigned GlobalsAS = CGM.getDataLayout().getDefaultGlobalsAddressSpace();
2516   unsigned ProgAS = CGM.getDataLayout().getProgramAddressSpace();
2517   llvm::Type *VTablePtrTy =
2518       llvm::FunctionType::get(CGM.Int32Ty, /*isVarArg=*/true)
2519           ->getPointerTo(ProgAS)
2520           ->getPointerTo(GlobalsAS);
2521   VTableField = Builder.CreatePointerBitCastOrAddrSpaceCast(
2522       VTableField, VTablePtrTy->getPointerTo(GlobalsAS));
2523   VTableAddressPoint = Builder.CreatePointerBitCastOrAddrSpaceCast(
2524       VTableAddressPoint, VTablePtrTy);
2525 
2526   llvm::StoreInst *Store = Builder.CreateStore(VTableAddressPoint, VTableField);
2527   TBAAAccessInfo TBAAInfo = CGM.getTBAAVTablePtrAccessInfo(VTablePtrTy);
2528   CGM.DecorateInstructionWithTBAA(Store, TBAAInfo);
2529   if (CGM.getCodeGenOpts().OptimizationLevel > 0 &&
2530       CGM.getCodeGenOpts().StrictVTablePointers)
2531     CGM.DecorateInstructionWithInvariantGroup(Store, Vptr.VTableClass);
2532 }
2533 
2534 CodeGenFunction::VPtrsVector
2535 CodeGenFunction::getVTablePointers(const CXXRecordDecl *VTableClass) {
2536   CodeGenFunction::VPtrsVector VPtrsResult;
2537   VisitedVirtualBasesSetTy VBases;
2538   getVTablePointers(BaseSubobject(VTableClass, CharUnits::Zero()),
2539                     /*NearestVBase=*/nullptr,
2540                     /*OffsetFromNearestVBase=*/CharUnits::Zero(),
2541                     /*BaseIsNonVirtualPrimaryBase=*/false, VTableClass, VBases,
2542                     VPtrsResult);
2543   return VPtrsResult;
2544 }
2545 
2546 void CodeGenFunction::getVTablePointers(BaseSubobject Base,
2547                                         const CXXRecordDecl *NearestVBase,
2548                                         CharUnits OffsetFromNearestVBase,
2549                                         bool BaseIsNonVirtualPrimaryBase,
2550                                         const CXXRecordDecl *VTableClass,
2551                                         VisitedVirtualBasesSetTy &VBases,
2552                                         VPtrsVector &Vptrs) {
2553   // If this base is a non-virtual primary base the address point has already
2554   // been set.
2555   if (!BaseIsNonVirtualPrimaryBase) {
2556     // Initialize the vtable pointer for this base.
2557     VPtr Vptr = {Base, NearestVBase, OffsetFromNearestVBase, VTableClass};
2558     Vptrs.push_back(Vptr);
2559   }
2560 
2561   const CXXRecordDecl *RD = Base.getBase();
2562 
2563   // Traverse bases.
2564   for (const auto &I : RD->bases()) {
2565     auto *BaseDecl =
2566         cast<CXXRecordDecl>(I.getType()->castAs<RecordType>()->getDecl());
2567 
2568     // Ignore classes without a vtable.
2569     if (!BaseDecl->isDynamicClass())
2570       continue;
2571 
2572     CharUnits BaseOffset;
2573     CharUnits BaseOffsetFromNearestVBase;
2574     bool BaseDeclIsNonVirtualPrimaryBase;
2575 
2576     if (I.isVirtual()) {
2577       // Check if we've visited this virtual base before.
2578       if (!VBases.insert(BaseDecl).second)
2579         continue;
2580 
2581       const ASTRecordLayout &Layout =
2582         getContext().getASTRecordLayout(VTableClass);
2583 
2584       BaseOffset = Layout.getVBaseClassOffset(BaseDecl);
2585       BaseOffsetFromNearestVBase = CharUnits::Zero();
2586       BaseDeclIsNonVirtualPrimaryBase = false;
2587     } else {
2588       const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
2589 
2590       BaseOffset = Base.getBaseOffset() + Layout.getBaseClassOffset(BaseDecl);
2591       BaseOffsetFromNearestVBase =
2592         OffsetFromNearestVBase + Layout.getBaseClassOffset(BaseDecl);
2593       BaseDeclIsNonVirtualPrimaryBase = Layout.getPrimaryBase() == BaseDecl;
2594     }
2595 
2596     getVTablePointers(
2597         BaseSubobject(BaseDecl, BaseOffset),
2598         I.isVirtual() ? BaseDecl : NearestVBase, BaseOffsetFromNearestVBase,
2599         BaseDeclIsNonVirtualPrimaryBase, VTableClass, VBases, Vptrs);
2600   }
2601 }
2602 
2603 void CodeGenFunction::InitializeVTablePointers(const CXXRecordDecl *RD) {
2604   // Ignore classes without a vtable.
2605   if (!RD->isDynamicClass())
2606     return;
2607 
2608   // Initialize the vtable pointers for this class and all of its bases.
2609   if (CGM.getCXXABI().doStructorsInitializeVPtrs(RD))
2610     for (const VPtr &Vptr : getVTablePointers(RD))
2611       InitializeVTablePointer(Vptr);
2612 
2613   if (RD->getNumVBases())
2614     CGM.getCXXABI().initializeHiddenVirtualInheritanceMembers(*this, RD);
2615 }
2616 
2617 llvm::Value *CodeGenFunction::GetVTablePtr(Address This,
2618                                            llvm::Type *VTableTy,
2619                                            const CXXRecordDecl *RD) {
2620   Address VTablePtrSrc = Builder.CreateElementBitCast(This, VTableTy);
2621   llvm::Instruction *VTable = Builder.CreateLoad(VTablePtrSrc, "vtable");
2622   TBAAAccessInfo TBAAInfo = CGM.getTBAAVTablePtrAccessInfo(VTableTy);
2623   CGM.DecorateInstructionWithTBAA(VTable, TBAAInfo);
2624 
2625   if (CGM.getCodeGenOpts().OptimizationLevel > 0 &&
2626       CGM.getCodeGenOpts().StrictVTablePointers)
2627     CGM.DecorateInstructionWithInvariantGroup(VTable, RD);
2628 
2629   return VTable;
2630 }
2631 
2632 // If a class has a single non-virtual base and does not introduce or override
2633 // virtual member functions or fields, it will have the same layout as its base.
2634 // This function returns the least derived such class.
2635 //
2636 // Casting an instance of a base class to such a derived class is technically
2637 // undefined behavior, but it is a relatively common hack for introducing member
2638 // functions on class instances with specific properties (e.g. llvm::Operator)
2639 // that works under most compilers and should not have security implications, so
2640 // we allow it by default. It can be disabled with -fsanitize=cfi-cast-strict.
2641 static const CXXRecordDecl *
2642 LeastDerivedClassWithSameLayout(const CXXRecordDecl *RD) {
2643   if (!RD->field_empty())
2644     return RD;
2645 
2646   if (RD->getNumVBases() != 0)
2647     return RD;
2648 
2649   if (RD->getNumBases() != 1)
2650     return RD;
2651 
2652   for (const CXXMethodDecl *MD : RD->methods()) {
2653     if (MD->isVirtual()) {
2654       // Virtual member functions are only ok if they are implicit destructors
2655       // because the implicit destructor will have the same semantics as the
2656       // base class's destructor if no fields are added.
2657       if (isa<CXXDestructorDecl>(MD) && MD->isImplicit())
2658         continue;
2659       return RD;
2660     }
2661   }
2662 
2663   return LeastDerivedClassWithSameLayout(
2664       RD->bases_begin()->getType()->getAsCXXRecordDecl());
2665 }
2666 
2667 void CodeGenFunction::EmitTypeMetadataCodeForVCall(const CXXRecordDecl *RD,
2668                                                    llvm::Value *VTable,
2669                                                    SourceLocation Loc) {
2670   if (SanOpts.has(SanitizerKind::CFIVCall))
2671     EmitVTablePtrCheckForCall(RD, VTable, CodeGenFunction::CFITCK_VCall, Loc);
2672   else if (CGM.getCodeGenOpts().WholeProgramVTables &&
2673            // Don't insert type test assumes if we are forcing public std
2674            // visibility.
2675            !CGM.HasLTOVisibilityPublicStd(RD)) {
2676     llvm::Metadata *MD =
2677         CGM.CreateMetadataIdentifierForType(QualType(RD->getTypeForDecl(), 0));
2678     llvm::Value *TypeId =
2679         llvm::MetadataAsValue::get(CGM.getLLVMContext(), MD);
2680 
2681     llvm::Value *CastedVTable = Builder.CreateBitCast(VTable, Int8PtrTy);
2682     llvm::Value *TypeTest =
2683         Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::type_test),
2684                            {CastedVTable, TypeId});
2685     Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::assume), TypeTest);
2686   }
2687 }
2688 
2689 void CodeGenFunction::EmitVTablePtrCheckForCall(const CXXRecordDecl *RD,
2690                                                 llvm::Value *VTable,
2691                                                 CFITypeCheckKind TCK,
2692                                                 SourceLocation Loc) {
2693   if (!SanOpts.has(SanitizerKind::CFICastStrict))
2694     RD = LeastDerivedClassWithSameLayout(RD);
2695 
2696   EmitVTablePtrCheck(RD, VTable, TCK, Loc);
2697 }
2698 
2699 void CodeGenFunction::EmitVTablePtrCheckForCast(QualType T,
2700                                                 llvm::Value *Derived,
2701                                                 bool MayBeNull,
2702                                                 CFITypeCheckKind TCK,
2703                                                 SourceLocation Loc) {
2704   if (!getLangOpts().CPlusPlus)
2705     return;
2706 
2707   auto *ClassTy = T->getAs<RecordType>();
2708   if (!ClassTy)
2709     return;
2710 
2711   const CXXRecordDecl *ClassDecl = cast<CXXRecordDecl>(ClassTy->getDecl());
2712 
2713   if (!ClassDecl->isCompleteDefinition() || !ClassDecl->isDynamicClass())
2714     return;
2715 
2716   if (!SanOpts.has(SanitizerKind::CFICastStrict))
2717     ClassDecl = LeastDerivedClassWithSameLayout(ClassDecl);
2718 
2719   llvm::BasicBlock *ContBlock = nullptr;
2720 
2721   if (MayBeNull) {
2722     llvm::Value *DerivedNotNull =
2723         Builder.CreateIsNotNull(Derived, "cast.nonnull");
2724 
2725     llvm::BasicBlock *CheckBlock = createBasicBlock("cast.check");
2726     ContBlock = createBasicBlock("cast.cont");
2727 
2728     Builder.CreateCondBr(DerivedNotNull, CheckBlock, ContBlock);
2729 
2730     EmitBlock(CheckBlock);
2731   }
2732 
2733   llvm::Value *VTable;
2734   std::tie(VTable, ClassDecl) = CGM.getCXXABI().LoadVTablePtr(
2735       *this, Address(Derived, getPointerAlign()), ClassDecl);
2736 
2737   EmitVTablePtrCheck(ClassDecl, VTable, TCK, Loc);
2738 
2739   if (MayBeNull) {
2740     Builder.CreateBr(ContBlock);
2741     EmitBlock(ContBlock);
2742   }
2743 }
2744 
2745 void CodeGenFunction::EmitVTablePtrCheck(const CXXRecordDecl *RD,
2746                                          llvm::Value *VTable,
2747                                          CFITypeCheckKind TCK,
2748                                          SourceLocation Loc) {
2749   if (!CGM.getCodeGenOpts().SanitizeCfiCrossDso &&
2750       !CGM.HasHiddenLTOVisibility(RD))
2751     return;
2752 
2753   SanitizerMask M;
2754   llvm::SanitizerStatKind SSK;
2755   switch (TCK) {
2756   case CFITCK_VCall:
2757     M = SanitizerKind::CFIVCall;
2758     SSK = llvm::SanStat_CFI_VCall;
2759     break;
2760   case CFITCK_NVCall:
2761     M = SanitizerKind::CFINVCall;
2762     SSK = llvm::SanStat_CFI_NVCall;
2763     break;
2764   case CFITCK_DerivedCast:
2765     M = SanitizerKind::CFIDerivedCast;
2766     SSK = llvm::SanStat_CFI_DerivedCast;
2767     break;
2768   case CFITCK_UnrelatedCast:
2769     M = SanitizerKind::CFIUnrelatedCast;
2770     SSK = llvm::SanStat_CFI_UnrelatedCast;
2771     break;
2772   case CFITCK_ICall:
2773   case CFITCK_NVMFCall:
2774   case CFITCK_VMFCall:
2775     llvm_unreachable("unexpected sanitizer kind");
2776   }
2777 
2778   std::string TypeName = RD->getQualifiedNameAsString();
2779   if (getContext().getSanitizerBlacklist().isBlacklistedType(M, TypeName))
2780     return;
2781 
2782   SanitizerScope SanScope(this);
2783   EmitSanitizerStatReport(SSK);
2784 
2785   llvm::Metadata *MD =
2786       CGM.CreateMetadataIdentifierForType(QualType(RD->getTypeForDecl(), 0));
2787   llvm::Value *TypeId = llvm::MetadataAsValue::get(getLLVMContext(), MD);
2788 
2789   llvm::Value *CastedVTable = Builder.CreateBitCast(VTable, Int8PtrTy);
2790   llvm::Value *TypeTest = Builder.CreateCall(
2791       CGM.getIntrinsic(llvm::Intrinsic::type_test), {CastedVTable, TypeId});
2792 
2793   llvm::Constant *StaticData[] = {
2794       llvm::ConstantInt::get(Int8Ty, TCK),
2795       EmitCheckSourceLocation(Loc),
2796       EmitCheckTypeDescriptor(QualType(RD->getTypeForDecl(), 0)),
2797   };
2798 
2799   auto CrossDsoTypeId = CGM.CreateCrossDsoCfiTypeId(MD);
2800   if (CGM.getCodeGenOpts().SanitizeCfiCrossDso && CrossDsoTypeId) {
2801     EmitCfiSlowPathCheck(M, TypeTest, CrossDsoTypeId, CastedVTable, StaticData);
2802     return;
2803   }
2804 
2805   if (CGM.getCodeGenOpts().SanitizeTrap.has(M)) {
2806     EmitTrapCheck(TypeTest, SanitizerHandler::CFICheckFail);
2807     return;
2808   }
2809 
2810   llvm::Value *AllVtables = llvm::MetadataAsValue::get(
2811       CGM.getLLVMContext(),
2812       llvm::MDString::get(CGM.getLLVMContext(), "all-vtables"));
2813   llvm::Value *ValidVtable = Builder.CreateCall(
2814       CGM.getIntrinsic(llvm::Intrinsic::type_test), {CastedVTable, AllVtables});
2815   EmitCheck(std::make_pair(TypeTest, M), SanitizerHandler::CFICheckFail,
2816             StaticData, {CastedVTable, ValidVtable});
2817 }
2818 
2819 bool CodeGenFunction::ShouldEmitVTableTypeCheckedLoad(const CXXRecordDecl *RD) {
2820   if (!CGM.getCodeGenOpts().WholeProgramVTables ||
2821       !CGM.HasHiddenLTOVisibility(RD))
2822     return false;
2823 
2824   if (CGM.getCodeGenOpts().VirtualFunctionElimination)
2825     return true;
2826 
2827   if (!SanOpts.has(SanitizerKind::CFIVCall) ||
2828       !CGM.getCodeGenOpts().SanitizeTrap.has(SanitizerKind::CFIVCall))
2829     return false;
2830 
2831   std::string TypeName = RD->getQualifiedNameAsString();
2832   return !getContext().getSanitizerBlacklist().isBlacklistedType(
2833       SanitizerKind::CFIVCall, TypeName);
2834 }
2835 
2836 llvm::Value *CodeGenFunction::EmitVTableTypeCheckedLoad(
2837     const CXXRecordDecl *RD, llvm::Value *VTable, uint64_t VTableByteOffset) {
2838   SanitizerScope SanScope(this);
2839 
2840   EmitSanitizerStatReport(llvm::SanStat_CFI_VCall);
2841 
2842   llvm::Metadata *MD =
2843       CGM.CreateMetadataIdentifierForType(QualType(RD->getTypeForDecl(), 0));
2844   llvm::Value *TypeId = llvm::MetadataAsValue::get(CGM.getLLVMContext(), MD);
2845 
2846   llvm::Value *CastedVTable = Builder.CreateBitCast(VTable, Int8PtrTy);
2847   llvm::Value *CheckedLoad = Builder.CreateCall(
2848       CGM.getIntrinsic(llvm::Intrinsic::type_checked_load),
2849       {CastedVTable, llvm::ConstantInt::get(Int32Ty, VTableByteOffset),
2850        TypeId});
2851   llvm::Value *CheckResult = Builder.CreateExtractValue(CheckedLoad, 1);
2852 
2853   std::string TypeName = RD->getQualifiedNameAsString();
2854   if (SanOpts.has(SanitizerKind::CFIVCall) &&
2855       !getContext().getSanitizerBlacklist().isBlacklistedType(
2856           SanitizerKind::CFIVCall, TypeName)) {
2857     EmitCheck(std::make_pair(CheckResult, SanitizerKind::CFIVCall),
2858               SanitizerHandler::CFICheckFail, {}, {});
2859   }
2860 
2861   return Builder.CreateBitCast(
2862       Builder.CreateExtractValue(CheckedLoad, 0),
2863       cast<llvm::PointerType>(VTable->getType())->getElementType());
2864 }
2865 
2866 void CodeGenFunction::EmitForwardingCallToLambda(
2867                                       const CXXMethodDecl *callOperator,
2868                                       CallArgList &callArgs) {
2869   // Get the address of the call operator.
2870   const CGFunctionInfo &calleeFnInfo =
2871     CGM.getTypes().arrangeCXXMethodDeclaration(callOperator);
2872   llvm::Constant *calleePtr =
2873     CGM.GetAddrOfFunction(GlobalDecl(callOperator),
2874                           CGM.getTypes().GetFunctionType(calleeFnInfo));
2875 
2876   // Prepare the return slot.
2877   const FunctionProtoType *FPT =
2878     callOperator->getType()->castAs<FunctionProtoType>();
2879   QualType resultType = FPT->getReturnType();
2880   ReturnValueSlot returnSlot;
2881   if (!resultType->isVoidType() &&
2882       calleeFnInfo.getReturnInfo().getKind() == ABIArgInfo::Indirect &&
2883       !hasScalarEvaluationKind(calleeFnInfo.getReturnType()))
2884     returnSlot =
2885         ReturnValueSlot(ReturnValue, resultType.isVolatileQualified(),
2886                         /*IsUnused=*/false, /*IsExternallyDestructed=*/true);
2887 
2888   // We don't need to separately arrange the call arguments because
2889   // the call can't be variadic anyway --- it's impossible to forward
2890   // variadic arguments.
2891 
2892   // Now emit our call.
2893   auto callee = CGCallee::forDirect(calleePtr, GlobalDecl(callOperator));
2894   RValue RV = EmitCall(calleeFnInfo, callee, returnSlot, callArgs);
2895 
2896   // If necessary, copy the returned value into the slot.
2897   if (!resultType->isVoidType() && returnSlot.isNull()) {
2898     if (getLangOpts().ObjCAutoRefCount && resultType->isObjCRetainableType()) {
2899       RV = RValue::get(EmitARCRetainAutoreleasedReturnValue(RV.getScalarVal()));
2900     }
2901     EmitReturnOfRValue(RV, resultType);
2902   } else
2903     EmitBranchThroughCleanup(ReturnBlock);
2904 }
2905 
2906 void CodeGenFunction::EmitLambdaBlockInvokeBody() {
2907   const BlockDecl *BD = BlockInfo->getBlockDecl();
2908   const VarDecl *variable = BD->capture_begin()->getVariable();
2909   const CXXRecordDecl *Lambda = variable->getType()->getAsCXXRecordDecl();
2910   const CXXMethodDecl *CallOp = Lambda->getLambdaCallOperator();
2911 
2912   if (CallOp->isVariadic()) {
2913     // FIXME: Making this work correctly is nasty because it requires either
2914     // cloning the body of the call operator or making the call operator
2915     // forward.
2916     CGM.ErrorUnsupported(CurCodeDecl, "lambda conversion to variadic function");
2917     return;
2918   }
2919 
2920   // Start building arguments for forwarding call
2921   CallArgList CallArgs;
2922 
2923   QualType ThisType = getContext().getPointerType(getContext().getRecordType(Lambda));
2924   Address ThisPtr = GetAddrOfBlockDecl(variable);
2925   CallArgs.add(RValue::get(ThisPtr.getPointer()), ThisType);
2926 
2927   // Add the rest of the parameters.
2928   for (auto param : BD->parameters())
2929     EmitDelegateCallArg(CallArgs, param, param->getBeginLoc());
2930 
2931   assert(!Lambda->isGenericLambda() &&
2932             "generic lambda interconversion to block not implemented");
2933   EmitForwardingCallToLambda(CallOp, CallArgs);
2934 }
2935 
2936 void CodeGenFunction::EmitLambdaDelegatingInvokeBody(const CXXMethodDecl *MD) {
2937   const CXXRecordDecl *Lambda = MD->getParent();
2938 
2939   // Start building arguments for forwarding call
2940   CallArgList CallArgs;
2941 
2942   QualType ThisType = getContext().getPointerType(getContext().getRecordType(Lambda));
2943   llvm::Value *ThisPtr = llvm::UndefValue::get(getTypes().ConvertType(ThisType));
2944   CallArgs.add(RValue::get(ThisPtr), ThisType);
2945 
2946   // Add the rest of the parameters.
2947   for (auto Param : MD->parameters())
2948     EmitDelegateCallArg(CallArgs, Param, Param->getBeginLoc());
2949 
2950   const CXXMethodDecl *CallOp = Lambda->getLambdaCallOperator();
2951   // For a generic lambda, find the corresponding call operator specialization
2952   // to which the call to the static-invoker shall be forwarded.
2953   if (Lambda->isGenericLambda()) {
2954     assert(MD->isFunctionTemplateSpecialization());
2955     const TemplateArgumentList *TAL = MD->getTemplateSpecializationArgs();
2956     FunctionTemplateDecl *CallOpTemplate = CallOp->getDescribedFunctionTemplate();
2957     void *InsertPos = nullptr;
2958     FunctionDecl *CorrespondingCallOpSpecialization =
2959         CallOpTemplate->findSpecialization(TAL->asArray(), InsertPos);
2960     assert(CorrespondingCallOpSpecialization);
2961     CallOp = cast<CXXMethodDecl>(CorrespondingCallOpSpecialization);
2962   }
2963   EmitForwardingCallToLambda(CallOp, CallArgs);
2964 }
2965 
2966 void CodeGenFunction::EmitLambdaStaticInvokeBody(const CXXMethodDecl *MD) {
2967   if (MD->isVariadic()) {
2968     // FIXME: Making this work correctly is nasty because it requires either
2969     // cloning the body of the call operator or making the call operator forward.
2970     CGM.ErrorUnsupported(MD, "lambda conversion to variadic function");
2971     return;
2972   }
2973 
2974   EmitLambdaDelegatingInvokeBody(MD);
2975 }
2976