1 //===--- CGClass.cpp - Emit LLVM Code for C++ classes -----------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This contains code dealing with C++ code generation of classes
12 //===----------------------------------------------------------------------===//
16 #include "CGDebugInfo.h"
17 #include "CGRecordLayout.h"
18 #include "CodeGenFunction.h"
19 #include "clang/AST/CXXInheritance.h"
20 #include "clang/AST/DeclTemplate.h"
21 #include "clang/AST/EvaluatedExprVisitor.h"
22 #include "clang/AST/RecordLayout.h"
23 #include "clang/AST/StmtCXX.h"
24 #include "clang/Basic/TargetBuiltins.h"
25 #include "clang/CodeGen/CGFunctionInfo.h"
26 #include "clang/Frontend/CodeGenOptions.h"
27 #include "llvm/IR/Intrinsics.h"
28 #include "llvm/IR/Metadata.h"
29 #include "llvm/Transforms/Utils/SanitizerStats.h"
31 using namespace clang;
32 using namespace CodeGen;
34 /// Return the best known alignment for an unknown pointer to a
36 CharUnits CodeGenModule::getClassPointerAlignment(const CXXRecordDecl *RD) {
37 if (!RD->isCompleteDefinition())
38 return CharUnits::One(); // Hopefully won't be used anywhere.
40 auto &layout = getContext().getASTRecordLayout(RD);
42 // If the class is final, then we know that the pointer points to an
43 // object of that type and can use the full alignment.
44 if (RD->hasAttr<FinalAttr>()) {
45 return layout.getAlignment();
47 // Otherwise, we have to assume it could be a subclass.
49 return layout.getNonVirtualAlignment();
53 /// Return the best known alignment for a pointer to a virtual base,
54 /// given the alignment of a pointer to the derived class.
55 CharUnits CodeGenModule::getVBaseAlignment(CharUnits actualDerivedAlign,
56 const CXXRecordDecl *derivedClass,
57 const CXXRecordDecl *vbaseClass) {
58 // The basic idea here is that an underaligned derived pointer might
59 // indicate an underaligned base pointer.
61 assert(vbaseClass->isCompleteDefinition());
62 auto &baseLayout = getContext().getASTRecordLayout(vbaseClass);
63 CharUnits expectedVBaseAlign = baseLayout.getNonVirtualAlignment();
65 return getDynamicOffsetAlignment(actualDerivedAlign, derivedClass,
70 CodeGenModule::getDynamicOffsetAlignment(CharUnits actualBaseAlign,
71 const CXXRecordDecl *baseDecl,
72 CharUnits expectedTargetAlign) {
73 // If the base is an incomplete type (which is, alas, possible with
74 // member pointers), be pessimistic.
75 if (!baseDecl->isCompleteDefinition())
76 return std::min(actualBaseAlign, expectedTargetAlign);
78 auto &baseLayout = getContext().getASTRecordLayout(baseDecl);
79 CharUnits expectedBaseAlign = baseLayout.getNonVirtualAlignment();
81 // If the class is properly aligned, assume the target offset is, too.
83 // This actually isn't necessarily the right thing to do --- if the
84 // class is a complete object, but it's only properly aligned for a
85 // base subobject, then the alignments of things relative to it are
86 // probably off as well. (Note that this requires the alignment of
87 // the target to be greater than the NV alignment of the derived
90 // However, our approach to this kind of under-alignment can only
91 // ever be best effort; after all, we're never going to propagate
92 // alignments through variables or parameters. Note, in particular,
93 // that constructing a polymorphic type in an address that's less
94 // than pointer-aligned will generally trap in the constructor,
95 // unless we someday add some sort of attribute to change the
96 // assumed alignment of 'this'. So our goal here is pretty much
97 // just to allow the user to explicitly say that a pointer is
98 // under-aligned and then safely access its fields and vtables.
99 if (actualBaseAlign >= expectedBaseAlign) {
100 return expectedTargetAlign;
103 // Otherwise, we might be offset by an arbitrary multiple of the
104 // actual alignment. The correct adjustment is to take the min of
105 // the two alignments.
106 return std::min(actualBaseAlign, expectedTargetAlign);
109 Address CodeGenFunction::LoadCXXThisAddress() {
110 assert(CurFuncDecl && "loading 'this' without a func declaration?");
111 assert(isa<CXXMethodDecl>(CurFuncDecl));
113 // Lazily compute CXXThisAlignment.
114 if (CXXThisAlignment.isZero()) {
115 // Just use the best known alignment for the parent.
116 // TODO: if we're currently emitting a complete-object ctor/dtor,
117 // we can always use the complete-object alignment.
118 auto RD = cast<CXXMethodDecl>(CurFuncDecl)->getParent();
119 CXXThisAlignment = CGM.getClassPointerAlignment(RD);
122 return Address(LoadCXXThis(), CXXThisAlignment);
125 /// Emit the address of a field using a member data pointer.
127 /// \param E Only used for emergency diagnostics
129 CodeGenFunction::EmitCXXMemberDataPointerAddress(const Expr *E, Address base,
130 llvm::Value *memberPtr,
131 const MemberPointerType *memberPtrType,
132 LValueBaseInfo *BaseInfo,
133 TBAAAccessInfo *TBAAInfo) {
134 // Ask the ABI to compute the actual address.
136 CGM.getCXXABI().EmitMemberDataPointerAddress(*this, E, base,
137 memberPtr, memberPtrType);
139 QualType memberType = memberPtrType->getPointeeType();
140 CharUnits memberAlign = getNaturalTypeAlignment(memberType, BaseInfo,
143 CGM.getDynamicOffsetAlignment(base.getAlignment(),
144 memberPtrType->getClass()->getAsCXXRecordDecl(),
146 return Address(ptr, memberAlign);
149 CharUnits CodeGenModule::computeNonVirtualBaseClassOffset(
150 const CXXRecordDecl *DerivedClass, CastExpr::path_const_iterator Start,
151 CastExpr::path_const_iterator End) {
152 CharUnits Offset = CharUnits::Zero();
154 const ASTContext &Context = getContext();
155 const CXXRecordDecl *RD = DerivedClass;
157 for (CastExpr::path_const_iterator I = Start; I != End; ++I) {
158 const CXXBaseSpecifier *Base = *I;
159 assert(!Base->isVirtual() && "Should not see virtual bases here!");
162 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
164 const CXXRecordDecl *BaseDecl =
165 cast<CXXRecordDecl>(Base->getType()->getAs<RecordType>()->getDecl());
168 Offset += Layout.getBaseClassOffset(BaseDecl);
177 CodeGenModule::GetNonVirtualBaseClassOffset(const CXXRecordDecl *ClassDecl,
178 CastExpr::path_const_iterator PathBegin,
179 CastExpr::path_const_iterator PathEnd) {
180 assert(PathBegin != PathEnd && "Base path should not be empty!");
183 computeNonVirtualBaseClassOffset(ClassDecl, PathBegin, PathEnd);
187 llvm::Type *PtrDiffTy =
188 Types.ConvertType(getContext().getPointerDiffType());
190 return llvm::ConstantInt::get(PtrDiffTy, Offset.getQuantity());
193 /// Gets the address of a direct base class within a complete object.
194 /// This should only be used for (1) non-virtual bases or (2) virtual bases
195 /// when the type is known to be complete (e.g. in complete destructors).
197 /// The object pointed to by 'This' is assumed to be non-null.
199 CodeGenFunction::GetAddressOfDirectBaseInCompleteClass(Address This,
200 const CXXRecordDecl *Derived,
201 const CXXRecordDecl *Base,
202 bool BaseIsVirtual) {
203 // 'this' must be a pointer (in some address space) to Derived.
204 assert(This.getElementType() == ConvertType(Derived));
206 // Compute the offset of the virtual base.
208 const ASTRecordLayout &Layout = getContext().getASTRecordLayout(Derived);
210 Offset = Layout.getVBaseClassOffset(Base);
212 Offset = Layout.getBaseClassOffset(Base);
214 // Shift and cast down to the base type.
215 // TODO: for complete types, this should be possible with a GEP.
217 if (!Offset.isZero()) {
218 V = Builder.CreateElementBitCast(V, Int8Ty);
219 V = Builder.CreateConstInBoundsByteGEP(V, Offset);
221 V = Builder.CreateElementBitCast(V, ConvertType(Base));
227 ApplyNonVirtualAndVirtualOffset(CodeGenFunction &CGF, Address addr,
228 CharUnits nonVirtualOffset,
229 llvm::Value *virtualOffset,
230 const CXXRecordDecl *derivedClass,
231 const CXXRecordDecl *nearestVBase) {
232 // Assert that we have something to do.
233 assert(!nonVirtualOffset.isZero() || virtualOffset != nullptr);
235 // Compute the offset from the static and dynamic components.
236 llvm::Value *baseOffset;
237 if (!nonVirtualOffset.isZero()) {
238 baseOffset = llvm::ConstantInt::get(CGF.PtrDiffTy,
239 nonVirtualOffset.getQuantity());
241 baseOffset = CGF.Builder.CreateAdd(virtualOffset, baseOffset);
244 baseOffset = virtualOffset;
247 // Apply the base offset.
248 llvm::Value *ptr = addr.getPointer();
249 ptr = CGF.Builder.CreateBitCast(ptr, CGF.Int8PtrTy);
250 ptr = CGF.Builder.CreateInBoundsGEP(ptr, baseOffset, "add.ptr");
252 // If we have a virtual component, the alignment of the result will
253 // be relative only to the known alignment of that vbase.
256 assert(nearestVBase && "virtual offset without vbase?");
257 alignment = CGF.CGM.getVBaseAlignment(addr.getAlignment(),
258 derivedClass, nearestVBase);
260 alignment = addr.getAlignment();
262 alignment = alignment.alignmentAtOffset(nonVirtualOffset);
264 return Address(ptr, alignment);
267 Address CodeGenFunction::GetAddressOfBaseClass(
268 Address Value, const CXXRecordDecl *Derived,
269 CastExpr::path_const_iterator PathBegin,
270 CastExpr::path_const_iterator PathEnd, bool NullCheckValue,
271 SourceLocation Loc) {
272 assert(PathBegin != PathEnd && "Base path should not be empty!");
274 CastExpr::path_const_iterator Start = PathBegin;
275 const CXXRecordDecl *VBase = nullptr;
277 // Sema has done some convenient canonicalization here: if the
278 // access path involved any virtual steps, the conversion path will
279 // *start* with a step down to the correct virtual base subobject,
280 // and hence will not require any further steps.
281 if ((*Start)->isVirtual()) {
283 cast<CXXRecordDecl>((*Start)->getType()->getAs<RecordType>()->getDecl());
287 // Compute the static offset of the ultimate destination within its
288 // allocating subobject (the virtual base, if there is one, or else
289 // the "complete" object that we see).
290 CharUnits NonVirtualOffset = CGM.computeNonVirtualBaseClassOffset(
291 VBase ? VBase : Derived, Start, PathEnd);
293 // If there's a virtual step, we can sometimes "devirtualize" it.
294 // For now, that's limited to when the derived type is final.
295 // TODO: "devirtualize" this for accesses to known-complete objects.
296 if (VBase && Derived->hasAttr<FinalAttr>()) {
297 const ASTRecordLayout &layout = getContext().getASTRecordLayout(Derived);
298 CharUnits vBaseOffset = layout.getVBaseClassOffset(VBase);
299 NonVirtualOffset += vBaseOffset;
300 VBase = nullptr; // we no longer have a virtual step
303 // Get the base pointer type.
304 llvm::Type *BasePtrTy =
305 ConvertType((PathEnd[-1])->getType())->getPointerTo();
307 QualType DerivedTy = getContext().getRecordType(Derived);
308 CharUnits DerivedAlign = CGM.getClassPointerAlignment(Derived);
310 // If the static offset is zero and we don't have a virtual step,
311 // just do a bitcast; null checks are unnecessary.
312 if (NonVirtualOffset.isZero() && !VBase) {
313 if (sanitizePerformTypeCheck()) {
314 SanitizerSet SkippedChecks;
315 SkippedChecks.set(SanitizerKind::Null, !NullCheckValue);
316 EmitTypeCheck(TCK_Upcast, Loc, Value.getPointer(),
317 DerivedTy, DerivedAlign, SkippedChecks);
319 return Builder.CreateBitCast(Value, BasePtrTy);
322 llvm::BasicBlock *origBB = nullptr;
323 llvm::BasicBlock *endBB = nullptr;
325 // Skip over the offset (and the vtable load) if we're supposed to
326 // null-check the pointer.
327 if (NullCheckValue) {
328 origBB = Builder.GetInsertBlock();
329 llvm::BasicBlock *notNullBB = createBasicBlock("cast.notnull");
330 endBB = createBasicBlock("cast.end");
332 llvm::Value *isNull = Builder.CreateIsNull(Value.getPointer());
333 Builder.CreateCondBr(isNull, endBB, notNullBB);
334 EmitBlock(notNullBB);
337 if (sanitizePerformTypeCheck()) {
338 SanitizerSet SkippedChecks;
339 SkippedChecks.set(SanitizerKind::Null, true);
340 EmitTypeCheck(VBase ? TCK_UpcastToVirtualBase : TCK_Upcast, Loc,
341 Value.getPointer(), DerivedTy, DerivedAlign, SkippedChecks);
344 // Compute the virtual offset.
345 llvm::Value *VirtualOffset = nullptr;
348 CGM.getCXXABI().GetVirtualBaseClassOffset(*this, Value, Derived, VBase);
351 // Apply both offsets.
352 Value = ApplyNonVirtualAndVirtualOffset(*this, Value, NonVirtualOffset,
353 VirtualOffset, Derived, VBase);
355 // Cast to the destination type.
356 Value = Builder.CreateBitCast(Value, BasePtrTy);
358 // Build a phi if we needed a null check.
359 if (NullCheckValue) {
360 llvm::BasicBlock *notNullBB = Builder.GetInsertBlock();
361 Builder.CreateBr(endBB);
364 llvm::PHINode *PHI = Builder.CreatePHI(BasePtrTy, 2, "cast.result");
365 PHI->addIncoming(Value.getPointer(), notNullBB);
366 PHI->addIncoming(llvm::Constant::getNullValue(BasePtrTy), origBB);
367 Value = Address(PHI, Value.getAlignment());
374 CodeGenFunction::GetAddressOfDerivedClass(Address BaseAddr,
375 const CXXRecordDecl *Derived,
376 CastExpr::path_const_iterator PathBegin,
377 CastExpr::path_const_iterator PathEnd,
378 bool NullCheckValue) {
379 assert(PathBegin != PathEnd && "Base path should not be empty!");
382 getContext().getCanonicalType(getContext().getTagDeclType(Derived));
383 llvm::Type *DerivedPtrTy = ConvertType(DerivedTy)->getPointerTo();
385 llvm::Value *NonVirtualOffset =
386 CGM.GetNonVirtualBaseClassOffset(Derived, PathBegin, PathEnd);
388 if (!NonVirtualOffset) {
389 // No offset, we can just cast back.
390 return Builder.CreateBitCast(BaseAddr, DerivedPtrTy);
393 llvm::BasicBlock *CastNull = nullptr;
394 llvm::BasicBlock *CastNotNull = nullptr;
395 llvm::BasicBlock *CastEnd = nullptr;
397 if (NullCheckValue) {
398 CastNull = createBasicBlock("cast.null");
399 CastNotNull = createBasicBlock("cast.notnull");
400 CastEnd = createBasicBlock("cast.end");
402 llvm::Value *IsNull = Builder.CreateIsNull(BaseAddr.getPointer());
403 Builder.CreateCondBr(IsNull, CastNull, CastNotNull);
404 EmitBlock(CastNotNull);
408 llvm::Value *Value = Builder.CreateBitCast(BaseAddr.getPointer(), Int8PtrTy);
409 Value = Builder.CreateGEP(Value, Builder.CreateNeg(NonVirtualOffset),
413 Value = Builder.CreateBitCast(Value, DerivedPtrTy);
415 // Produce a PHI if we had a null-check.
416 if (NullCheckValue) {
417 Builder.CreateBr(CastEnd);
419 Builder.CreateBr(CastEnd);
422 llvm::PHINode *PHI = Builder.CreatePHI(Value->getType(), 2);
423 PHI->addIncoming(Value, CastNotNull);
424 PHI->addIncoming(llvm::Constant::getNullValue(Value->getType()), CastNull);
428 return Address(Value, CGM.getClassPointerAlignment(Derived));
431 llvm::Value *CodeGenFunction::GetVTTParameter(GlobalDecl GD,
434 if (!CGM.getCXXABI().NeedsVTTParameter(GD)) {
435 // This constructor/destructor does not need a VTT parameter.
439 const CXXRecordDecl *RD = cast<CXXMethodDecl>(CurCodeDecl)->getParent();
440 const CXXRecordDecl *Base = cast<CXXMethodDecl>(GD.getDecl())->getParent();
444 uint64_t SubVTTIndex;
447 // If this is a delegating constructor call, just load the VTT.
449 } else if (RD == Base) {
450 // If the record matches the base, this is the complete ctor/dtor
451 // variant calling the base variant in a class with virtual bases.
452 assert(!CGM.getCXXABI().NeedsVTTParameter(CurGD) &&
453 "doing no-op VTT offset in base dtor/ctor?");
454 assert(!ForVirtualBase && "Can't have same class as virtual base!");
457 const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
458 CharUnits BaseOffset = ForVirtualBase ?
459 Layout.getVBaseClassOffset(Base) :
460 Layout.getBaseClassOffset(Base);
463 CGM.getVTables().getSubVTTIndex(RD, BaseSubobject(Base, BaseOffset));
464 assert(SubVTTIndex != 0 && "Sub-VTT index must be greater than zero!");
467 if (CGM.getCXXABI().NeedsVTTParameter(CurGD)) {
468 // A VTT parameter was passed to the constructor, use it.
470 VTT = Builder.CreateConstInBoundsGEP1_64(VTT, SubVTTIndex);
472 // We're the complete constructor, so get the VTT by name.
473 VTT = CGM.getVTables().GetAddrOfVTT(RD);
474 VTT = Builder.CreateConstInBoundsGEP2_64(VTT, 0, SubVTTIndex);
481 /// Call the destructor for a direct base class.
482 struct CallBaseDtor final : EHScopeStack::Cleanup {
483 const CXXRecordDecl *BaseClass;
485 CallBaseDtor(const CXXRecordDecl *Base, bool BaseIsVirtual)
486 : BaseClass(Base), BaseIsVirtual(BaseIsVirtual) {}
488 void Emit(CodeGenFunction &CGF, Flags flags) override {
489 const CXXRecordDecl *DerivedClass =
490 cast<CXXMethodDecl>(CGF.CurCodeDecl)->getParent();
492 const CXXDestructorDecl *D = BaseClass->getDestructor();
494 CGF.GetAddressOfDirectBaseInCompleteClass(CGF.LoadCXXThisAddress(),
495 DerivedClass, BaseClass,
497 CGF.EmitCXXDestructorCall(D, Dtor_Base, BaseIsVirtual,
498 /*Delegating=*/false, Addr);
502 /// A visitor which checks whether an initializer uses 'this' in a
503 /// way which requires the vtable to be properly set.
504 struct DynamicThisUseChecker : ConstEvaluatedExprVisitor<DynamicThisUseChecker> {
505 typedef ConstEvaluatedExprVisitor<DynamicThisUseChecker> super;
509 DynamicThisUseChecker(const ASTContext &C) : super(C), UsesThis(false) {}
511 // Black-list all explicit and implicit references to 'this'.
513 // Do we need to worry about external references to 'this' derived
514 // from arbitrary code? If so, then anything which runs arbitrary
515 // external code might potentially access the vtable.
516 void VisitCXXThisExpr(const CXXThisExpr *E) { UsesThis = true; }
518 } // end anonymous namespace
520 static bool BaseInitializerUsesThis(ASTContext &C, const Expr *Init) {
521 DynamicThisUseChecker Checker(C);
523 return Checker.UsesThis;
526 static void EmitBaseInitializer(CodeGenFunction &CGF,
527 const CXXRecordDecl *ClassDecl,
528 CXXCtorInitializer *BaseInit,
529 CXXCtorType CtorType) {
530 assert(BaseInit->isBaseInitializer() &&
531 "Must have base initializer!");
533 Address ThisPtr = CGF.LoadCXXThisAddress();
535 const Type *BaseType = BaseInit->getBaseClass();
536 CXXRecordDecl *BaseClassDecl =
537 cast<CXXRecordDecl>(BaseType->getAs<RecordType>()->getDecl());
539 bool isBaseVirtual = BaseInit->isBaseVirtual();
541 // The base constructor doesn't construct virtual bases.
542 if (CtorType == Ctor_Base && isBaseVirtual)
545 // If the initializer for the base (other than the constructor
546 // itself) accesses 'this' in any way, we need to initialize the
548 if (BaseInitializerUsesThis(CGF.getContext(), BaseInit->getInit()))
549 CGF.InitializeVTablePointers(ClassDecl);
551 // We can pretend to be a complete class because it only matters for
552 // virtual bases, and we only do virtual bases for complete ctors.
554 CGF.GetAddressOfDirectBaseInCompleteClass(ThisPtr, ClassDecl,
557 AggValueSlot AggSlot =
558 AggValueSlot::forAddr(V, Qualifiers(),
559 AggValueSlot::IsDestructed,
560 AggValueSlot::DoesNotNeedGCBarriers,
561 AggValueSlot::IsNotAliased);
563 CGF.EmitAggExpr(BaseInit->getInit(), AggSlot);
565 if (CGF.CGM.getLangOpts().Exceptions &&
566 !BaseClassDecl->hasTrivialDestructor())
567 CGF.EHStack.pushCleanup<CallBaseDtor>(EHCleanup, BaseClassDecl,
571 static bool isMemcpyEquivalentSpecialMember(const CXXMethodDecl *D) {
572 auto *CD = dyn_cast<CXXConstructorDecl>(D);
573 if (!(CD && CD->isCopyOrMoveConstructor()) &&
574 !D->isCopyAssignmentOperator() && !D->isMoveAssignmentOperator())
577 // We can emit a memcpy for a trivial copy or move constructor/assignment.
578 if (D->isTrivial() && !D->getParent()->mayInsertExtraPadding())
581 // We *must* emit a memcpy for a defaulted union copy or move op.
582 if (D->getParent()->isUnion() && D->isDefaulted())
588 static void EmitLValueForAnyFieldInitialization(CodeGenFunction &CGF,
589 CXXCtorInitializer *MemberInit,
591 FieldDecl *Field = MemberInit->getAnyMember();
592 if (MemberInit->isIndirectMemberInitializer()) {
593 // If we are initializing an anonymous union field, drill down to the field.
594 IndirectFieldDecl *IndirectField = MemberInit->getIndirectMember();
595 for (const auto *I : IndirectField->chain())
596 LHS = CGF.EmitLValueForFieldInitialization(LHS, cast<FieldDecl>(I));
598 LHS = CGF.EmitLValueForFieldInitialization(LHS, Field);
602 static void EmitMemberInitializer(CodeGenFunction &CGF,
603 const CXXRecordDecl *ClassDecl,
604 CXXCtorInitializer *MemberInit,
605 const CXXConstructorDecl *Constructor,
606 FunctionArgList &Args) {
607 ApplyDebugLocation Loc(CGF, MemberInit->getSourceLocation());
608 assert(MemberInit->isAnyMemberInitializer() &&
609 "Must have member initializer!");
610 assert(MemberInit->getInit() && "Must have initializer!");
612 // non-static data member initializers.
613 FieldDecl *Field = MemberInit->getAnyMember();
614 QualType FieldType = Field->getType();
616 llvm::Value *ThisPtr = CGF.LoadCXXThis();
617 QualType RecordTy = CGF.getContext().getTypeDeclType(ClassDecl);
618 LValue LHS = CGF.MakeNaturalAlignAddrLValue(ThisPtr, RecordTy);
620 EmitLValueForAnyFieldInitialization(CGF, MemberInit, LHS);
622 // Special case: if we are in a copy or move constructor, and we are copying
623 // an array of PODs or classes with trivial copy constructors, ignore the
624 // AST and perform the copy we know is equivalent.
625 // FIXME: This is hacky at best... if we had a bit more explicit information
626 // in the AST, we could generalize it more easily.
627 const ConstantArrayType *Array
628 = CGF.getContext().getAsConstantArrayType(FieldType);
629 if (Array && Constructor->isDefaulted() &&
630 Constructor->isCopyOrMoveConstructor()) {
631 QualType BaseElementTy = CGF.getContext().getBaseElementType(Array);
632 CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(MemberInit->getInit());
633 if (BaseElementTy.isPODType(CGF.getContext()) ||
634 (CE && isMemcpyEquivalentSpecialMember(CE->getConstructor()))) {
635 unsigned SrcArgIndex =
636 CGF.CGM.getCXXABI().getSrcArgforCopyCtor(Constructor, Args);
638 = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(Args[SrcArgIndex]));
639 LValue ThisRHSLV = CGF.MakeNaturalAlignAddrLValue(SrcPtr, RecordTy);
640 LValue Src = CGF.EmitLValueForFieldInitialization(ThisRHSLV, Field);
642 // Copy the aggregate.
643 CGF.EmitAggregateCopy(LHS.getAddress(), Src.getAddress(), FieldType,
644 LHS.isVolatileQualified());
645 // Ensure that we destroy the objects if an exception is thrown later in
647 QualType::DestructionKind dtorKind = FieldType.isDestructedType();
648 if (CGF.needsEHCleanup(dtorKind))
649 CGF.pushEHDestroy(dtorKind, LHS.getAddress(), FieldType);
654 CGF.EmitInitializerForField(Field, LHS, MemberInit->getInit());
657 void CodeGenFunction::EmitInitializerForField(FieldDecl *Field, LValue LHS,
659 QualType FieldType = Field->getType();
660 switch (getEvaluationKind(FieldType)) {
662 if (LHS.isSimple()) {
663 EmitExprAsInit(Init, Field, LHS, false);
665 RValue RHS = RValue::get(EmitScalarExpr(Init));
666 EmitStoreThroughLValue(RHS, LHS);
670 EmitComplexExprIntoLValue(Init, LHS, /*isInit*/ true);
672 case TEK_Aggregate: {
674 AggValueSlot::forLValue(LHS,
675 AggValueSlot::IsDestructed,
676 AggValueSlot::DoesNotNeedGCBarriers,
677 AggValueSlot::IsNotAliased);
678 EmitAggExpr(Init, Slot);
683 // Ensure that we destroy this object if an exception is thrown
684 // later in the constructor.
685 QualType::DestructionKind dtorKind = FieldType.isDestructedType();
686 if (needsEHCleanup(dtorKind))
687 pushEHDestroy(dtorKind, LHS.getAddress(), FieldType);
690 /// Checks whether the given constructor is a valid subject for the
691 /// complete-to-base constructor delegation optimization, i.e.
692 /// emitting the complete constructor as a simple call to the base
694 bool CodeGenFunction::IsConstructorDelegationValid(
695 const CXXConstructorDecl *Ctor) {
697 // Currently we disable the optimization for classes with virtual
698 // bases because (1) the addresses of parameter variables need to be
699 // consistent across all initializers but (2) the delegate function
700 // call necessarily creates a second copy of the parameter variable.
702 // The limiting example (purely theoretical AFAIK):
703 // struct A { A(int &c) { c++; } };
704 // struct B : virtual A {
705 // B(int count) : A(count) { printf("%d\n", count); }
707 // ...although even this example could in principle be emitted as a
708 // delegation since the address of the parameter doesn't escape.
709 if (Ctor->getParent()->getNumVBases()) {
710 // TODO: white-list trivial vbase initializers. This case wouldn't
711 // be subject to the restrictions below.
713 // TODO: white-list cases where:
714 // - there are no non-reference parameters to the constructor
715 // - the initializers don't access any non-reference parameters
716 // - the initializers don't take the address of non-reference
719 // If we ever add any of the above cases, remember that:
720 // - function-try-blocks will always blacklist this optimization
721 // - we need to perform the constructor prologue and cleanup in
722 // EmitConstructorBody.
727 // We also disable the optimization for variadic functions because
728 // it's impossible to "re-pass" varargs.
729 if (Ctor->getType()->getAs<FunctionProtoType>()->isVariadic())
732 // FIXME: Decide if we can do a delegation of a delegating constructor.
733 if (Ctor->isDelegatingConstructor())
739 // Emit code in ctor (Prologue==true) or dtor (Prologue==false)
740 // to poison the extra field paddings inserted under
741 // -fsanitize-address-field-padding=1|2.
742 void CodeGenFunction::EmitAsanPrologueOrEpilogue(bool Prologue) {
743 ASTContext &Context = getContext();
744 const CXXRecordDecl *ClassDecl =
745 Prologue ? cast<CXXConstructorDecl>(CurGD.getDecl())->getParent()
746 : cast<CXXDestructorDecl>(CurGD.getDecl())->getParent();
747 if (!ClassDecl->mayInsertExtraPadding()) return;
749 struct SizeAndOffset {
754 unsigned PtrSize = CGM.getDataLayout().getPointerSizeInBits();
755 const ASTRecordLayout &Info = Context.getASTRecordLayout(ClassDecl);
757 // Populate sizes and offsets of fields.
758 SmallVector<SizeAndOffset, 16> SSV(Info.getFieldCount());
759 for (unsigned i = 0, e = Info.getFieldCount(); i != e; ++i)
761 Context.toCharUnitsFromBits(Info.getFieldOffset(i)).getQuantity();
763 size_t NumFields = 0;
764 for (const auto *Field : ClassDecl->fields()) {
765 const FieldDecl *D = Field;
766 std::pair<CharUnits, CharUnits> FieldInfo =
767 Context.getTypeInfoInChars(D->getType());
768 CharUnits FieldSize = FieldInfo.first;
769 assert(NumFields < SSV.size());
770 SSV[NumFields].Size = D->isBitField() ? 0 : FieldSize.getQuantity();
773 assert(NumFields == SSV.size());
774 if (SSV.size() <= 1) return;
776 // We will insert calls to __asan_* run-time functions.
777 // LLVM AddressSanitizer pass may decide to inline them later.
778 llvm::Type *Args[2] = {IntPtrTy, IntPtrTy};
779 llvm::FunctionType *FTy =
780 llvm::FunctionType::get(CGM.VoidTy, Args, false);
781 llvm::Constant *F = CGM.CreateRuntimeFunction(
782 FTy, Prologue ? "__asan_poison_intra_object_redzone"
783 : "__asan_unpoison_intra_object_redzone");
785 llvm::Value *ThisPtr = LoadCXXThis();
786 ThisPtr = Builder.CreatePtrToInt(ThisPtr, IntPtrTy);
787 uint64_t TypeSize = Info.getNonVirtualSize().getQuantity();
788 // For each field check if it has sufficient padding,
789 // if so (un)poison it with a call.
790 for (size_t i = 0; i < SSV.size(); i++) {
791 uint64_t AsanAlignment = 8;
792 uint64_t NextField = i == SSV.size() - 1 ? TypeSize : SSV[i + 1].Offset;
793 uint64_t PoisonSize = NextField - SSV[i].Offset - SSV[i].Size;
794 uint64_t EndOffset = SSV[i].Offset + SSV[i].Size;
795 if (PoisonSize < AsanAlignment || !SSV[i].Size ||
796 (NextField % AsanAlignment) != 0)
799 F, {Builder.CreateAdd(ThisPtr, Builder.getIntN(PtrSize, EndOffset)),
800 Builder.getIntN(PtrSize, PoisonSize)});
804 /// EmitConstructorBody - Emits the body of the current constructor.
805 void CodeGenFunction::EmitConstructorBody(FunctionArgList &Args) {
806 EmitAsanPrologueOrEpilogue(true);
807 const CXXConstructorDecl *Ctor = cast<CXXConstructorDecl>(CurGD.getDecl());
808 CXXCtorType CtorType = CurGD.getCtorType();
810 assert((CGM.getTarget().getCXXABI().hasConstructorVariants() ||
811 CtorType == Ctor_Complete) &&
812 "can only generate complete ctor for this ABI");
814 // Before we go any further, try the complete->base constructor
815 // delegation optimization.
816 if (CtorType == Ctor_Complete && IsConstructorDelegationValid(Ctor) &&
817 CGM.getTarget().getCXXABI().hasConstructorVariants()) {
818 EmitDelegateCXXConstructorCall(Ctor, Ctor_Base, Args, Ctor->getLocEnd());
822 const FunctionDecl *Definition = nullptr;
823 Stmt *Body = Ctor->getBody(Definition);
824 assert(Definition == Ctor && "emitting wrong constructor body");
826 // Enter the function-try-block before the constructor prologue if
828 bool IsTryBody = (Body && isa<CXXTryStmt>(Body));
830 EnterCXXTryStmt(*cast<CXXTryStmt>(Body), true);
832 incrementProfileCounter(Body);
834 RunCleanupsScope RunCleanups(*this);
836 // TODO: in restricted cases, we can emit the vbase initializers of
837 // a complete ctor and then delegate to the base ctor.
839 // Emit the constructor prologue, i.e. the base and member
841 EmitCtorPrologue(Ctor, CtorType, Args);
843 // Emit the body of the statement.
845 EmitStmt(cast<CXXTryStmt>(Body)->getTryBlock());
849 // Emit any cleanup blocks associated with the member or base
850 // initializers, which includes (along the exceptional path) the
851 // destructors for those members and bases that were fully
853 RunCleanups.ForceCleanup();
856 ExitCXXTryStmt(*cast<CXXTryStmt>(Body), true);
860 /// RAII object to indicate that codegen is copying the value representation
861 /// instead of the object representation. Useful when copying a struct or
862 /// class which has uninitialized members and we're only performing
863 /// lvalue-to-rvalue conversion on the object but not its members.
864 class CopyingValueRepresentation {
866 explicit CopyingValueRepresentation(CodeGenFunction &CGF)
867 : CGF(CGF), OldSanOpts(CGF.SanOpts) {
868 CGF.SanOpts.set(SanitizerKind::Bool, false);
869 CGF.SanOpts.set(SanitizerKind::Enum, false);
871 ~CopyingValueRepresentation() {
872 CGF.SanOpts = OldSanOpts;
875 CodeGenFunction &CGF;
876 SanitizerSet OldSanOpts;
878 } // end anonymous namespace
881 class FieldMemcpyizer {
883 FieldMemcpyizer(CodeGenFunction &CGF, const CXXRecordDecl *ClassDecl,
884 const VarDecl *SrcRec)
885 : CGF(CGF), ClassDecl(ClassDecl), SrcRec(SrcRec),
886 RecLayout(CGF.getContext().getASTRecordLayout(ClassDecl)),
887 FirstField(nullptr), LastField(nullptr), FirstFieldOffset(0),
888 LastFieldOffset(0), LastAddedFieldIndex(0) {}
890 bool isMemcpyableField(FieldDecl *F) const {
891 // Never memcpy fields when we are adding poisoned paddings.
892 if (CGF.getContext().getLangOpts().SanitizeAddressFieldPadding)
894 Qualifiers Qual = F->getType().getQualifiers();
895 if (Qual.hasVolatile() || Qual.hasObjCLifetime())
900 void addMemcpyableField(FieldDecl *F) {
907 CharUnits getMemcpySize(uint64_t FirstByteOffset) const {
908 unsigned LastFieldSize =
909 LastField->isBitField() ?
910 LastField->getBitWidthValue(CGF.getContext()) :
911 CGF.getContext().getTypeSize(LastField->getType());
912 uint64_t MemcpySizeBits =
913 LastFieldOffset + LastFieldSize - FirstByteOffset +
914 CGF.getContext().getCharWidth() - 1;
915 CharUnits MemcpySize =
916 CGF.getContext().toCharUnitsFromBits(MemcpySizeBits);
921 // Give the subclass a chance to bail out if it feels the memcpy isn't
922 // worth it (e.g. Hasn't aggregated enough data).
927 uint64_t FirstByteOffset;
928 if (FirstField->isBitField()) {
929 const CGRecordLayout &RL =
930 CGF.getTypes().getCGRecordLayout(FirstField->getParent());
931 const CGBitFieldInfo &BFInfo = RL.getBitFieldInfo(FirstField);
932 // FirstFieldOffset is not appropriate for bitfields,
933 // we need to use the storage offset instead.
934 FirstByteOffset = CGF.getContext().toBits(BFInfo.StorageOffset);
936 FirstByteOffset = FirstFieldOffset;
939 CharUnits MemcpySize = getMemcpySize(FirstByteOffset);
940 QualType RecordTy = CGF.getContext().getTypeDeclType(ClassDecl);
941 Address ThisPtr = CGF.LoadCXXThisAddress();
942 LValue DestLV = CGF.MakeAddrLValue(ThisPtr, RecordTy);
943 LValue Dest = CGF.EmitLValueForFieldInitialization(DestLV, FirstField);
944 llvm::Value *SrcPtr = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(SrcRec));
945 LValue SrcLV = CGF.MakeNaturalAlignAddrLValue(SrcPtr, RecordTy);
946 LValue Src = CGF.EmitLValueForFieldInitialization(SrcLV, FirstField);
948 emitMemcpyIR(Dest.isBitField() ? Dest.getBitFieldAddress() : Dest.getAddress(),
949 Src.isBitField() ? Src.getBitFieldAddress() : Src.getAddress(),
955 FirstField = nullptr;
959 CodeGenFunction &CGF;
960 const CXXRecordDecl *ClassDecl;
963 void emitMemcpyIR(Address DestPtr, Address SrcPtr, CharUnits Size) {
964 llvm::PointerType *DPT = DestPtr.getType();
966 llvm::Type::getInt8PtrTy(CGF.getLLVMContext(), DPT->getAddressSpace());
967 DestPtr = CGF.Builder.CreateBitCast(DestPtr, DBP);
969 llvm::PointerType *SPT = SrcPtr.getType();
971 llvm::Type::getInt8PtrTy(CGF.getLLVMContext(), SPT->getAddressSpace());
972 SrcPtr = CGF.Builder.CreateBitCast(SrcPtr, SBP);
974 CGF.Builder.CreateMemCpy(DestPtr, SrcPtr, Size.getQuantity());
977 void addInitialField(FieldDecl *F) {
980 FirstFieldOffset = RecLayout.getFieldOffset(F->getFieldIndex());
981 LastFieldOffset = FirstFieldOffset;
982 LastAddedFieldIndex = F->getFieldIndex();
985 void addNextField(FieldDecl *F) {
986 // For the most part, the following invariant will hold:
987 // F->getFieldIndex() == LastAddedFieldIndex + 1
988 // The one exception is that Sema won't add a copy-initializer for an
989 // unnamed bitfield, which will show up here as a gap in the sequence.
990 assert(F->getFieldIndex() >= LastAddedFieldIndex + 1 &&
991 "Cannot aggregate fields out of order.");
992 LastAddedFieldIndex = F->getFieldIndex();
994 // The 'first' and 'last' fields are chosen by offset, rather than field
995 // index. This allows the code to support bitfields, as well as regular
997 uint64_t FOffset = RecLayout.getFieldOffset(F->getFieldIndex());
998 if (FOffset < FirstFieldOffset) {
1000 FirstFieldOffset = FOffset;
1001 } else if (FOffset > LastFieldOffset) {
1003 LastFieldOffset = FOffset;
1007 const VarDecl *SrcRec;
1008 const ASTRecordLayout &RecLayout;
1009 FieldDecl *FirstField;
1010 FieldDecl *LastField;
1011 uint64_t FirstFieldOffset, LastFieldOffset;
1012 unsigned LastAddedFieldIndex;
1015 class ConstructorMemcpyizer : public FieldMemcpyizer {
1017 /// Get source argument for copy constructor. Returns null if not a copy
1019 static const VarDecl *getTrivialCopySource(CodeGenFunction &CGF,
1020 const CXXConstructorDecl *CD,
1021 FunctionArgList &Args) {
1022 if (CD->isCopyOrMoveConstructor() && CD->isDefaulted())
1023 return Args[CGF.CGM.getCXXABI().getSrcArgforCopyCtor(CD, Args)];
1027 // Returns true if a CXXCtorInitializer represents a member initialization
1028 // that can be rolled into a memcpy.
1029 bool isMemberInitMemcpyable(CXXCtorInitializer *MemberInit) const {
1030 if (!MemcpyableCtor)
1032 FieldDecl *Field = MemberInit->getMember();
1033 assert(Field && "No field for member init.");
1034 QualType FieldType = Field->getType();
1035 CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(MemberInit->getInit());
1037 // Bail out on non-memcpyable, not-trivially-copyable members.
1038 if (!(CE && isMemcpyEquivalentSpecialMember(CE->getConstructor())) &&
1039 !(FieldType.isTriviallyCopyableType(CGF.getContext()) ||
1040 FieldType->isReferenceType()))
1043 // Bail out on volatile fields.
1044 if (!isMemcpyableField(Field))
1047 // Otherwise we're good.
1052 ConstructorMemcpyizer(CodeGenFunction &CGF, const CXXConstructorDecl *CD,
1053 FunctionArgList &Args)
1054 : FieldMemcpyizer(CGF, CD->getParent(), getTrivialCopySource(CGF, CD, Args)),
1055 ConstructorDecl(CD),
1056 MemcpyableCtor(CD->isDefaulted() &&
1057 CD->isCopyOrMoveConstructor() &&
1058 CGF.getLangOpts().getGC() == LangOptions::NonGC),
1061 void addMemberInitializer(CXXCtorInitializer *MemberInit) {
1062 if (isMemberInitMemcpyable(MemberInit)) {
1063 AggregatedInits.push_back(MemberInit);
1064 addMemcpyableField(MemberInit->getMember());
1066 emitAggregatedInits();
1067 EmitMemberInitializer(CGF, ConstructorDecl->getParent(), MemberInit,
1068 ConstructorDecl, Args);
1072 void emitAggregatedInits() {
1073 if (AggregatedInits.size() <= 1) {
1074 // This memcpy is too small to be worthwhile. Fall back on default
1076 if (!AggregatedInits.empty()) {
1077 CopyingValueRepresentation CVR(CGF);
1078 EmitMemberInitializer(CGF, ConstructorDecl->getParent(),
1079 AggregatedInits[0], ConstructorDecl, Args);
1080 AggregatedInits.clear();
1086 pushEHDestructors();
1088 AggregatedInits.clear();
1091 void pushEHDestructors() {
1092 Address ThisPtr = CGF.LoadCXXThisAddress();
1093 QualType RecordTy = CGF.getContext().getTypeDeclType(ClassDecl);
1094 LValue LHS = CGF.MakeAddrLValue(ThisPtr, RecordTy);
1096 for (unsigned i = 0; i < AggregatedInits.size(); ++i) {
1097 CXXCtorInitializer *MemberInit = AggregatedInits[i];
1098 QualType FieldType = MemberInit->getAnyMember()->getType();
1099 QualType::DestructionKind dtorKind = FieldType.isDestructedType();
1100 if (!CGF.needsEHCleanup(dtorKind))
1102 LValue FieldLHS = LHS;
1103 EmitLValueForAnyFieldInitialization(CGF, MemberInit, FieldLHS);
1104 CGF.pushEHDestroy(dtorKind, FieldLHS.getAddress(), FieldType);
1109 emitAggregatedInits();
1113 const CXXConstructorDecl *ConstructorDecl;
1114 bool MemcpyableCtor;
1115 FunctionArgList &Args;
1116 SmallVector<CXXCtorInitializer*, 16> AggregatedInits;
1119 class AssignmentMemcpyizer : public FieldMemcpyizer {
1121 // Returns the memcpyable field copied by the given statement, if one
1122 // exists. Otherwise returns null.
1123 FieldDecl *getMemcpyableField(Stmt *S) {
1124 if (!AssignmentsMemcpyable)
1126 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(S)) {
1127 // Recognise trivial assignments.
1128 if (BO->getOpcode() != BO_Assign)
1130 MemberExpr *ME = dyn_cast<MemberExpr>(BO->getLHS());
1133 FieldDecl *Field = dyn_cast<FieldDecl>(ME->getMemberDecl());
1134 if (!Field || !isMemcpyableField(Field))
1136 Stmt *RHS = BO->getRHS();
1137 if (ImplicitCastExpr *EC = dyn_cast<ImplicitCastExpr>(RHS))
1138 RHS = EC->getSubExpr();
1141 if (MemberExpr *ME2 = dyn_cast<MemberExpr>(RHS)) {
1142 if (ME2->getMemberDecl() == Field)
1146 } else if (CXXMemberCallExpr *MCE = dyn_cast<CXXMemberCallExpr>(S)) {
1147 CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MCE->getCalleeDecl());
1148 if (!(MD && isMemcpyEquivalentSpecialMember(MD)))
1150 MemberExpr *IOA = dyn_cast<MemberExpr>(MCE->getImplicitObjectArgument());
1153 FieldDecl *Field = dyn_cast<FieldDecl>(IOA->getMemberDecl());
1154 if (!Field || !isMemcpyableField(Field))
1156 MemberExpr *Arg0 = dyn_cast<MemberExpr>(MCE->getArg(0));
1157 if (!Arg0 || Field != dyn_cast<FieldDecl>(Arg0->getMemberDecl()))
1160 } else if (CallExpr *CE = dyn_cast<CallExpr>(S)) {
1161 FunctionDecl *FD = dyn_cast<FunctionDecl>(CE->getCalleeDecl());
1162 if (!FD || FD->getBuiltinID() != Builtin::BI__builtin_memcpy)
1164 Expr *DstPtr = CE->getArg(0);
1165 if (ImplicitCastExpr *DC = dyn_cast<ImplicitCastExpr>(DstPtr))
1166 DstPtr = DC->getSubExpr();
1167 UnaryOperator *DUO = dyn_cast<UnaryOperator>(DstPtr);
1168 if (!DUO || DUO->getOpcode() != UO_AddrOf)
1170 MemberExpr *ME = dyn_cast<MemberExpr>(DUO->getSubExpr());
1173 FieldDecl *Field = dyn_cast<FieldDecl>(ME->getMemberDecl());
1174 if (!Field || !isMemcpyableField(Field))
1176 Expr *SrcPtr = CE->getArg(1);
1177 if (ImplicitCastExpr *SC = dyn_cast<ImplicitCastExpr>(SrcPtr))
1178 SrcPtr = SC->getSubExpr();
1179 UnaryOperator *SUO = dyn_cast<UnaryOperator>(SrcPtr);
1180 if (!SUO || SUO->getOpcode() != UO_AddrOf)
1182 MemberExpr *ME2 = dyn_cast<MemberExpr>(SUO->getSubExpr());
1183 if (!ME2 || Field != dyn_cast<FieldDecl>(ME2->getMemberDecl()))
1191 bool AssignmentsMemcpyable;
1192 SmallVector<Stmt*, 16> AggregatedStmts;
1195 AssignmentMemcpyizer(CodeGenFunction &CGF, const CXXMethodDecl *AD,
1196 FunctionArgList &Args)
1197 : FieldMemcpyizer(CGF, AD->getParent(), Args[Args.size() - 1]),
1198 AssignmentsMemcpyable(CGF.getLangOpts().getGC() == LangOptions::NonGC) {
1199 assert(Args.size() == 2);
1202 void emitAssignment(Stmt *S) {
1203 FieldDecl *F = getMemcpyableField(S);
1205 addMemcpyableField(F);
1206 AggregatedStmts.push_back(S);
1208 emitAggregatedStmts();
1213 void emitAggregatedStmts() {
1214 if (AggregatedStmts.size() <= 1) {
1215 if (!AggregatedStmts.empty()) {
1216 CopyingValueRepresentation CVR(CGF);
1217 CGF.EmitStmt(AggregatedStmts[0]);
1223 AggregatedStmts.clear();
1227 emitAggregatedStmts();
1230 } // end anonymous namespace
1232 static bool isInitializerOfDynamicClass(const CXXCtorInitializer *BaseInit) {
1233 const Type *BaseType = BaseInit->getBaseClass();
1234 const auto *BaseClassDecl =
1235 cast<CXXRecordDecl>(BaseType->getAs<RecordType>()->getDecl());
1236 return BaseClassDecl->isDynamicClass();
1239 /// EmitCtorPrologue - This routine generates necessary code to initialize
1240 /// base classes and non-static data members belonging to this constructor.
1241 void CodeGenFunction::EmitCtorPrologue(const CXXConstructorDecl *CD,
1242 CXXCtorType CtorType,
1243 FunctionArgList &Args) {
1244 if (CD->isDelegatingConstructor())
1245 return EmitDelegatingCXXConstructorCall(CD, Args);
1247 const CXXRecordDecl *ClassDecl = CD->getParent();
1249 CXXConstructorDecl::init_const_iterator B = CD->init_begin(),
1252 llvm::BasicBlock *BaseCtorContinueBB = nullptr;
1253 if (ClassDecl->getNumVBases() &&
1254 !CGM.getTarget().getCXXABI().hasConstructorVariants()) {
1255 // The ABIs that don't have constructor variants need to put a branch
1256 // before the virtual base initialization code.
1257 BaseCtorContinueBB =
1258 CGM.getCXXABI().EmitCtorCompleteObjectHandler(*this, ClassDecl);
1259 assert(BaseCtorContinueBB);
1262 llvm::Value *const OldThis = CXXThisValue;
1263 // Virtual base initializers first.
1264 for (; B != E && (*B)->isBaseInitializer() && (*B)->isBaseVirtual(); B++) {
1265 if (CGM.getCodeGenOpts().StrictVTablePointers &&
1266 CGM.getCodeGenOpts().OptimizationLevel > 0 &&
1267 isInitializerOfDynamicClass(*B))
1268 CXXThisValue = Builder.CreateInvariantGroupBarrier(LoadCXXThis());
1269 EmitBaseInitializer(*this, ClassDecl, *B, CtorType);
1272 if (BaseCtorContinueBB) {
1273 // Complete object handler should continue to the remaining initializers.
1274 Builder.CreateBr(BaseCtorContinueBB);
1275 EmitBlock(BaseCtorContinueBB);
1278 // Then, non-virtual base initializers.
1279 for (; B != E && (*B)->isBaseInitializer(); B++) {
1280 assert(!(*B)->isBaseVirtual());
1282 if (CGM.getCodeGenOpts().StrictVTablePointers &&
1283 CGM.getCodeGenOpts().OptimizationLevel > 0 &&
1284 isInitializerOfDynamicClass(*B))
1285 CXXThisValue = Builder.CreateInvariantGroupBarrier(LoadCXXThis());
1286 EmitBaseInitializer(*this, ClassDecl, *B, CtorType);
1289 CXXThisValue = OldThis;
1291 InitializeVTablePointers(ClassDecl);
1293 // And finally, initialize class members.
1294 FieldConstructionScope FCS(*this, LoadCXXThisAddress());
1295 ConstructorMemcpyizer CM(*this, CD, Args);
1296 for (; B != E; B++) {
1297 CXXCtorInitializer *Member = (*B);
1298 assert(!Member->isBaseInitializer());
1299 assert(Member->isAnyMemberInitializer() &&
1300 "Delegating initializer on non-delegating constructor");
1301 CM.addMemberInitializer(Member);
1307 FieldHasTrivialDestructorBody(ASTContext &Context, const FieldDecl *Field);
1310 HasTrivialDestructorBody(ASTContext &Context,
1311 const CXXRecordDecl *BaseClassDecl,
1312 const CXXRecordDecl *MostDerivedClassDecl)
1314 // If the destructor is trivial we don't have to check anything else.
1315 if (BaseClassDecl->hasTrivialDestructor())
1318 if (!BaseClassDecl->getDestructor()->hasTrivialBody())
1322 for (const auto *Field : BaseClassDecl->fields())
1323 if (!FieldHasTrivialDestructorBody(Context, Field))
1326 // Check non-virtual bases.
1327 for (const auto &I : BaseClassDecl->bases()) {
1331 const CXXRecordDecl *NonVirtualBase =
1332 cast<CXXRecordDecl>(I.getType()->castAs<RecordType>()->getDecl());
1333 if (!HasTrivialDestructorBody(Context, NonVirtualBase,
1334 MostDerivedClassDecl))
1338 if (BaseClassDecl == MostDerivedClassDecl) {
1339 // Check virtual bases.
1340 for (const auto &I : BaseClassDecl->vbases()) {
1341 const CXXRecordDecl *VirtualBase =
1342 cast<CXXRecordDecl>(I.getType()->castAs<RecordType>()->getDecl());
1343 if (!HasTrivialDestructorBody(Context, VirtualBase,
1344 MostDerivedClassDecl))
1353 FieldHasTrivialDestructorBody(ASTContext &Context,
1354 const FieldDecl *Field)
1356 QualType FieldBaseElementType = Context.getBaseElementType(Field->getType());
1358 const RecordType *RT = FieldBaseElementType->getAs<RecordType>();
1362 CXXRecordDecl *FieldClassDecl = cast<CXXRecordDecl>(RT->getDecl());
1364 // The destructor for an implicit anonymous union member is never invoked.
1365 if (FieldClassDecl->isUnion() && FieldClassDecl->isAnonymousStructOrUnion())
1368 return HasTrivialDestructorBody(Context, FieldClassDecl, FieldClassDecl);
1371 /// CanSkipVTablePointerInitialization - Check whether we need to initialize
1372 /// any vtable pointers before calling this destructor.
1373 static bool CanSkipVTablePointerInitialization(CodeGenFunction &CGF,
1374 const CXXDestructorDecl *Dtor) {
1375 const CXXRecordDecl *ClassDecl = Dtor->getParent();
1376 if (!ClassDecl->isDynamicClass())
1379 if (!Dtor->hasTrivialBody())
1382 // Check the fields.
1383 for (const auto *Field : ClassDecl->fields())
1384 if (!FieldHasTrivialDestructorBody(CGF.getContext(), Field))
1390 /// EmitDestructorBody - Emits the body of the current destructor.
1391 void CodeGenFunction::EmitDestructorBody(FunctionArgList &Args) {
1392 const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CurGD.getDecl());
1393 CXXDtorType DtorType = CurGD.getDtorType();
1395 // For an abstract class, non-base destructors are never used (and can't
1396 // be emitted in general, because vbase dtors may not have been validated
1397 // by Sema), but the Itanium ABI doesn't make them optional and Clang may
1398 // in fact emit references to them from other compilations, so emit them
1399 // as functions containing a trap instruction.
1400 if (DtorType != Dtor_Base && Dtor->getParent()->isAbstract()) {
1401 llvm::CallInst *TrapCall = EmitTrapCall(llvm::Intrinsic::trap);
1402 TrapCall->setDoesNotReturn();
1403 TrapCall->setDoesNotThrow();
1404 Builder.CreateUnreachable();
1405 Builder.ClearInsertionPoint();
1409 Stmt *Body = Dtor->getBody();
1411 incrementProfileCounter(Body);
1413 // The call to operator delete in a deleting destructor happens
1414 // outside of the function-try-block, which means it's always
1415 // possible to delegate the destructor body to the complete
1416 // destructor. Do so.
1417 if (DtorType == Dtor_Deleting) {
1418 RunCleanupsScope DtorEpilogue(*this);
1419 EnterDtorCleanups(Dtor, Dtor_Deleting);
1420 if (HaveInsertPoint())
1421 EmitCXXDestructorCall(Dtor, Dtor_Complete, /*ForVirtualBase=*/false,
1422 /*Delegating=*/false, LoadCXXThisAddress());
1426 // If the body is a function-try-block, enter the try before
1428 bool isTryBody = (Body && isa<CXXTryStmt>(Body));
1430 EnterCXXTryStmt(*cast<CXXTryStmt>(Body), true);
1431 EmitAsanPrologueOrEpilogue(false);
1433 // Enter the epilogue cleanups.
1434 RunCleanupsScope DtorEpilogue(*this);
1436 // If this is the complete variant, just invoke the base variant;
1437 // the epilogue will destruct the virtual bases. But we can't do
1438 // this optimization if the body is a function-try-block, because
1439 // we'd introduce *two* handler blocks. In the Microsoft ABI, we
1440 // always delegate because we might not have a definition in this TU.
1442 case Dtor_Comdat: llvm_unreachable("not expecting a COMDAT");
1443 case Dtor_Deleting: llvm_unreachable("already handled deleting case");
1446 assert((Body || getTarget().getCXXABI().isMicrosoft()) &&
1447 "can't emit a dtor without a body for non-Microsoft ABIs");
1449 // Enter the cleanup scopes for virtual bases.
1450 EnterDtorCleanups(Dtor, Dtor_Complete);
1453 EmitCXXDestructorCall(Dtor, Dtor_Base, /*ForVirtualBase=*/false,
1454 /*Delegating=*/false, LoadCXXThisAddress());
1458 // Fallthrough: act like we're in the base variant.
1464 // Enter the cleanup scopes for fields and non-virtual bases.
1465 EnterDtorCleanups(Dtor, Dtor_Base);
1467 // Initialize the vtable pointers before entering the body.
1468 if (!CanSkipVTablePointerInitialization(*this, Dtor)) {
1469 // Insert the llvm.invariant.group.barrier intrinsic before initializing
1470 // the vptrs to cancel any previous assumptions we might have made.
1471 if (CGM.getCodeGenOpts().StrictVTablePointers &&
1472 CGM.getCodeGenOpts().OptimizationLevel > 0)
1473 CXXThisValue = Builder.CreateInvariantGroupBarrier(LoadCXXThis());
1474 InitializeVTablePointers(Dtor->getParent());
1478 EmitStmt(cast<CXXTryStmt>(Body)->getTryBlock());
1482 assert(Dtor->isImplicit() && "bodyless dtor not implicit");
1483 // nothing to do besides what's in the epilogue
1485 // -fapple-kext must inline any call to this dtor into
1486 // the caller's body.
1487 if (getLangOpts().AppleKext)
1488 CurFn->addFnAttr(llvm::Attribute::AlwaysInline);
1493 // Jump out through the epilogue cleanups.
1494 DtorEpilogue.ForceCleanup();
1496 // Exit the try if applicable.
1498 ExitCXXTryStmt(*cast<CXXTryStmt>(Body), true);
1501 void CodeGenFunction::emitImplicitAssignmentOperatorBody(FunctionArgList &Args) {
1502 const CXXMethodDecl *AssignOp = cast<CXXMethodDecl>(CurGD.getDecl());
1503 const Stmt *RootS = AssignOp->getBody();
1504 assert(isa<CompoundStmt>(RootS) &&
1505 "Body of an implicit assignment operator should be compound stmt.");
1506 const CompoundStmt *RootCS = cast<CompoundStmt>(RootS);
1508 LexicalScope Scope(*this, RootCS->getSourceRange());
1510 incrementProfileCounter(RootCS);
1511 AssignmentMemcpyizer AM(*this, AssignOp, Args);
1512 for (auto *I : RootCS->body())
1513 AM.emitAssignment(I);
1518 llvm::Value *LoadThisForDtorDelete(CodeGenFunction &CGF,
1519 const CXXDestructorDecl *DD) {
1520 if (Expr *ThisArg = DD->getOperatorDeleteThisArg())
1521 return CGF.EmitScalarExpr(ThisArg);
1522 return CGF.LoadCXXThis();
1525 /// Call the operator delete associated with the current destructor.
1526 struct CallDtorDelete final : EHScopeStack::Cleanup {
1529 void Emit(CodeGenFunction &CGF, Flags flags) override {
1530 const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CGF.CurCodeDecl);
1531 const CXXRecordDecl *ClassDecl = Dtor->getParent();
1532 CGF.EmitDeleteCall(Dtor->getOperatorDelete(),
1533 LoadThisForDtorDelete(CGF, Dtor),
1534 CGF.getContext().getTagDeclType(ClassDecl));
1538 void EmitConditionalDtorDeleteCall(CodeGenFunction &CGF,
1539 llvm::Value *ShouldDeleteCondition,
1540 bool ReturnAfterDelete) {
1541 llvm::BasicBlock *callDeleteBB = CGF.createBasicBlock("dtor.call_delete");
1542 llvm::BasicBlock *continueBB = CGF.createBasicBlock("dtor.continue");
1543 llvm::Value *ShouldCallDelete
1544 = CGF.Builder.CreateIsNull(ShouldDeleteCondition);
1545 CGF.Builder.CreateCondBr(ShouldCallDelete, continueBB, callDeleteBB);
1547 CGF.EmitBlock(callDeleteBB);
1548 const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CGF.CurCodeDecl);
1549 const CXXRecordDecl *ClassDecl = Dtor->getParent();
1550 CGF.EmitDeleteCall(Dtor->getOperatorDelete(),
1551 LoadThisForDtorDelete(CGF, Dtor),
1552 CGF.getContext().getTagDeclType(ClassDecl));
1553 assert(Dtor->getOperatorDelete()->isDestroyingOperatorDelete() ==
1554 ReturnAfterDelete &&
1555 "unexpected value for ReturnAfterDelete");
1556 if (ReturnAfterDelete)
1557 CGF.EmitBranchThroughCleanup(CGF.ReturnBlock);
1559 CGF.Builder.CreateBr(continueBB);
1561 CGF.EmitBlock(continueBB);
1564 struct CallDtorDeleteConditional final : EHScopeStack::Cleanup {
1565 llvm::Value *ShouldDeleteCondition;
1568 CallDtorDeleteConditional(llvm::Value *ShouldDeleteCondition)
1569 : ShouldDeleteCondition(ShouldDeleteCondition) {
1570 assert(ShouldDeleteCondition != nullptr);
1573 void Emit(CodeGenFunction &CGF, Flags flags) override {
1574 EmitConditionalDtorDeleteCall(CGF, ShouldDeleteCondition,
1575 /*ReturnAfterDelete*/false);
1579 class DestroyField final : public EHScopeStack::Cleanup {
1580 const FieldDecl *field;
1581 CodeGenFunction::Destroyer *destroyer;
1582 bool useEHCleanupForArray;
1585 DestroyField(const FieldDecl *field, CodeGenFunction::Destroyer *destroyer,
1586 bool useEHCleanupForArray)
1587 : field(field), destroyer(destroyer),
1588 useEHCleanupForArray(useEHCleanupForArray) {}
1590 void Emit(CodeGenFunction &CGF, Flags flags) override {
1591 // Find the address of the field.
1592 Address thisValue = CGF.LoadCXXThisAddress();
1593 QualType RecordTy = CGF.getContext().getTagDeclType(field->getParent());
1594 LValue ThisLV = CGF.MakeAddrLValue(thisValue, RecordTy);
1595 LValue LV = CGF.EmitLValueForField(ThisLV, field);
1596 assert(LV.isSimple());
1598 CGF.emitDestroy(LV.getAddress(), field->getType(), destroyer,
1599 flags.isForNormalCleanup() && useEHCleanupForArray);
1603 static void EmitSanitizerDtorCallback(CodeGenFunction &CGF, llvm::Value *Ptr,
1604 CharUnits::QuantityType PoisonSize) {
1605 CodeGenFunction::SanitizerScope SanScope(&CGF);
1606 // Pass in void pointer and size of region as arguments to runtime
1608 llvm::Value *Args[] = {CGF.Builder.CreateBitCast(Ptr, CGF.VoidPtrTy),
1609 llvm::ConstantInt::get(CGF.SizeTy, PoisonSize)};
1611 llvm::Type *ArgTypes[] = {CGF.VoidPtrTy, CGF.SizeTy};
1613 llvm::FunctionType *FnType =
1614 llvm::FunctionType::get(CGF.VoidTy, ArgTypes, false);
1616 CGF.CGM.CreateRuntimeFunction(FnType, "__sanitizer_dtor_callback");
1617 CGF.EmitNounwindRuntimeCall(Fn, Args);
1620 class SanitizeDtorMembers final : public EHScopeStack::Cleanup {
1621 const CXXDestructorDecl *Dtor;
1624 SanitizeDtorMembers(const CXXDestructorDecl *Dtor) : Dtor(Dtor) {}
1626 // Generate function call for handling object poisoning.
1627 // Disables tail call elimination, to prevent the current stack frame
1628 // from disappearing from the stack trace.
1629 void Emit(CodeGenFunction &CGF, Flags flags) override {
1630 const ASTRecordLayout &Layout =
1631 CGF.getContext().getASTRecordLayout(Dtor->getParent());
1633 // Nothing to poison.
1634 if (Layout.getFieldCount() == 0)
1637 // Prevent the current stack frame from disappearing from the stack trace.
1638 CGF.CurFn->addFnAttr("disable-tail-calls", "true");
1640 // Construct pointer to region to begin poisoning, and calculate poison
1641 // size, so that only members declared in this class are poisoned.
1642 ASTContext &Context = CGF.getContext();
1643 unsigned fieldIndex = 0;
1644 int startIndex = -1;
1645 // RecordDecl::field_iterator Field;
1646 for (const FieldDecl *Field : Dtor->getParent()->fields()) {
1647 // Poison field if it is trivial
1648 if (FieldHasTrivialDestructorBody(Context, Field)) {
1649 // Start sanitizing at this field
1651 startIndex = fieldIndex;
1653 // Currently on the last field, and it must be poisoned with the
1655 if (fieldIndex == Layout.getFieldCount() - 1) {
1656 PoisonMembers(CGF, startIndex, Layout.getFieldCount());
1658 } else if (startIndex >= 0) {
1659 // No longer within a block of memory to poison, so poison the block
1660 PoisonMembers(CGF, startIndex, fieldIndex);
1661 // Re-set the start index
1669 /// \param layoutStartOffset index of the ASTRecordLayout field to
1670 /// start poisoning (inclusive)
1671 /// \param layoutEndOffset index of the ASTRecordLayout field to
1672 /// end poisoning (exclusive)
1673 void PoisonMembers(CodeGenFunction &CGF, unsigned layoutStartOffset,
1674 unsigned layoutEndOffset) {
1675 ASTContext &Context = CGF.getContext();
1676 const ASTRecordLayout &Layout =
1677 Context.getASTRecordLayout(Dtor->getParent());
1679 llvm::ConstantInt *OffsetSizePtr = llvm::ConstantInt::get(
1681 Context.toCharUnitsFromBits(Layout.getFieldOffset(layoutStartOffset))
1684 llvm::Value *OffsetPtr = CGF.Builder.CreateGEP(
1685 CGF.Builder.CreateBitCast(CGF.LoadCXXThis(), CGF.Int8PtrTy),
1688 CharUnits::QuantityType PoisonSize;
1689 if (layoutEndOffset >= Layout.getFieldCount()) {
1690 PoisonSize = Layout.getNonVirtualSize().getQuantity() -
1691 Context.toCharUnitsFromBits(
1692 Layout.getFieldOffset(layoutStartOffset))
1695 PoisonSize = Context.toCharUnitsFromBits(
1696 Layout.getFieldOffset(layoutEndOffset) -
1697 Layout.getFieldOffset(layoutStartOffset))
1701 if (PoisonSize == 0)
1704 EmitSanitizerDtorCallback(CGF, OffsetPtr, PoisonSize);
1708 class SanitizeDtorVTable final : public EHScopeStack::Cleanup {
1709 const CXXDestructorDecl *Dtor;
1712 SanitizeDtorVTable(const CXXDestructorDecl *Dtor) : Dtor(Dtor) {}
1714 // Generate function call for handling vtable pointer poisoning.
1715 void Emit(CodeGenFunction &CGF, Flags flags) override {
1716 assert(Dtor->getParent()->isDynamicClass());
1718 ASTContext &Context = CGF.getContext();
1719 // Poison vtable and vtable ptr if they exist for this class.
1720 llvm::Value *VTablePtr = CGF.LoadCXXThis();
1722 CharUnits::QuantityType PoisonSize =
1723 Context.toCharUnitsFromBits(CGF.PointerWidthInBits).getQuantity();
1724 // Pass in void pointer and size of region as arguments to runtime
1726 EmitSanitizerDtorCallback(CGF, VTablePtr, PoisonSize);
1729 } // end anonymous namespace
1731 /// \brief Emit all code that comes at the end of class's
1732 /// destructor. This is to call destructors on members and base classes
1733 /// in reverse order of their construction.
1735 /// For a deleting destructor, this also handles the case where a destroying
1736 /// operator delete completely overrides the definition.
1737 void CodeGenFunction::EnterDtorCleanups(const CXXDestructorDecl *DD,
1738 CXXDtorType DtorType) {
1739 assert((!DD->isTrivial() || DD->hasAttr<DLLExportAttr>()) &&
1740 "Should not emit dtor epilogue for non-exported trivial dtor!");
1742 // The deleting-destructor phase just needs to call the appropriate
1743 // operator delete that Sema picked up.
1744 if (DtorType == Dtor_Deleting) {
1745 assert(DD->getOperatorDelete() &&
1746 "operator delete missing - EnterDtorCleanups");
1747 if (CXXStructorImplicitParamValue) {
1748 // If there is an implicit param to the deleting dtor, it's a boolean
1749 // telling whether this is a deleting destructor.
1750 if (DD->getOperatorDelete()->isDestroyingOperatorDelete())
1751 EmitConditionalDtorDeleteCall(*this, CXXStructorImplicitParamValue,
1752 /*ReturnAfterDelete*/true);
1754 EHStack.pushCleanup<CallDtorDeleteConditional>(
1755 NormalAndEHCleanup, CXXStructorImplicitParamValue);
1757 if (DD->getOperatorDelete()->isDestroyingOperatorDelete()) {
1758 const CXXRecordDecl *ClassDecl = DD->getParent();
1759 EmitDeleteCall(DD->getOperatorDelete(),
1760 LoadThisForDtorDelete(*this, DD),
1761 getContext().getTagDeclType(ClassDecl));
1762 EmitBranchThroughCleanup(ReturnBlock);
1764 EHStack.pushCleanup<CallDtorDelete>(NormalAndEHCleanup);
1770 const CXXRecordDecl *ClassDecl = DD->getParent();
1772 // Unions have no bases and do not call field destructors.
1773 if (ClassDecl->isUnion())
1776 // The complete-destructor phase just destructs all the virtual bases.
1777 if (DtorType == Dtor_Complete) {
1778 // Poison the vtable pointer such that access after the base
1779 // and member destructors are invoked is invalid.
1780 if (CGM.getCodeGenOpts().SanitizeMemoryUseAfterDtor &&
1781 SanOpts.has(SanitizerKind::Memory) && ClassDecl->getNumVBases() &&
1782 ClassDecl->isPolymorphic())
1783 EHStack.pushCleanup<SanitizeDtorVTable>(NormalAndEHCleanup, DD);
1785 // We push them in the forward order so that they'll be popped in
1786 // the reverse order.
1787 for (const auto &Base : ClassDecl->vbases()) {
1788 CXXRecordDecl *BaseClassDecl
1789 = cast<CXXRecordDecl>(Base.getType()->getAs<RecordType>()->getDecl());
1791 // Ignore trivial destructors.
1792 if (BaseClassDecl->hasTrivialDestructor())
1795 EHStack.pushCleanup<CallBaseDtor>(NormalAndEHCleanup,
1797 /*BaseIsVirtual*/ true);
1803 assert(DtorType == Dtor_Base);
1804 // Poison the vtable pointer if it has no virtual bases, but inherits
1805 // virtual functions.
1806 if (CGM.getCodeGenOpts().SanitizeMemoryUseAfterDtor &&
1807 SanOpts.has(SanitizerKind::Memory) && !ClassDecl->getNumVBases() &&
1808 ClassDecl->isPolymorphic())
1809 EHStack.pushCleanup<SanitizeDtorVTable>(NormalAndEHCleanup, DD);
1811 // Destroy non-virtual bases.
1812 for (const auto &Base : ClassDecl->bases()) {
1813 // Ignore virtual bases.
1814 if (Base.isVirtual())
1817 CXXRecordDecl *BaseClassDecl = Base.getType()->getAsCXXRecordDecl();
1819 // Ignore trivial destructors.
1820 if (BaseClassDecl->hasTrivialDestructor())
1823 EHStack.pushCleanup<CallBaseDtor>(NormalAndEHCleanup,
1825 /*BaseIsVirtual*/ false);
1828 // Poison fields such that access after their destructors are
1829 // invoked, and before the base class destructor runs, is invalid.
1830 if (CGM.getCodeGenOpts().SanitizeMemoryUseAfterDtor &&
1831 SanOpts.has(SanitizerKind::Memory))
1832 EHStack.pushCleanup<SanitizeDtorMembers>(NormalAndEHCleanup, DD);
1834 // Destroy direct fields.
1835 for (const auto *Field : ClassDecl->fields()) {
1836 QualType type = Field->getType();
1837 QualType::DestructionKind dtorKind = type.isDestructedType();
1838 if (!dtorKind) continue;
1840 // Anonymous union members do not have their destructors called.
1841 const RecordType *RT = type->getAsUnionType();
1842 if (RT && RT->getDecl()->isAnonymousStructOrUnion()) continue;
1844 CleanupKind cleanupKind = getCleanupKind(dtorKind);
1845 EHStack.pushCleanup<DestroyField>(cleanupKind, Field,
1846 getDestroyer(dtorKind),
1847 cleanupKind & EHCleanup);
1851 /// EmitCXXAggrConstructorCall - Emit a loop to call a particular
1852 /// constructor for each of several members of an array.
1854 /// \param ctor the constructor to call for each element
1855 /// \param arrayType the type of the array to initialize
1856 /// \param arrayBegin an arrayType*
1857 /// \param zeroInitialize true if each element should be
1858 /// zero-initialized before it is constructed
1859 void CodeGenFunction::EmitCXXAggrConstructorCall(
1860 const CXXConstructorDecl *ctor, const ArrayType *arrayType,
1861 Address arrayBegin, const CXXConstructExpr *E, bool zeroInitialize) {
1862 QualType elementType;
1863 llvm::Value *numElements =
1864 emitArrayLength(arrayType, elementType, arrayBegin);
1866 EmitCXXAggrConstructorCall(ctor, numElements, arrayBegin, E, zeroInitialize);
1869 /// EmitCXXAggrConstructorCall - Emit a loop to call a particular
1870 /// constructor for each of several members of an array.
1872 /// \param ctor the constructor to call for each element
1873 /// \param numElements the number of elements in the array;
1875 /// \param arrayBase a T*, where T is the type constructed by ctor
1876 /// \param zeroInitialize true if each element should be
1877 /// zero-initialized before it is constructed
1878 void CodeGenFunction::EmitCXXAggrConstructorCall(const CXXConstructorDecl *ctor,
1879 llvm::Value *numElements,
1881 const CXXConstructExpr *E,
1882 bool zeroInitialize) {
1883 // It's legal for numElements to be zero. This can happen both
1884 // dynamically, because x can be zero in 'new A[x]', and statically,
1885 // because of GCC extensions that permit zero-length arrays. There
1886 // are probably legitimate places where we could assume that this
1887 // doesn't happen, but it's not clear that it's worth it.
1888 llvm::BranchInst *zeroCheckBranch = nullptr;
1890 // Optimize for a constant count.
1891 llvm::ConstantInt *constantCount
1892 = dyn_cast<llvm::ConstantInt>(numElements);
1893 if (constantCount) {
1894 // Just skip out if the constant count is zero.
1895 if (constantCount->isZero()) return;
1897 // Otherwise, emit the check.
1899 llvm::BasicBlock *loopBB = createBasicBlock("new.ctorloop");
1900 llvm::Value *iszero = Builder.CreateIsNull(numElements, "isempty");
1901 zeroCheckBranch = Builder.CreateCondBr(iszero, loopBB, loopBB);
1905 // Find the end of the array.
1906 llvm::Value *arrayBegin = arrayBase.getPointer();
1907 llvm::Value *arrayEnd = Builder.CreateInBoundsGEP(arrayBegin, numElements,
1910 // Enter the loop, setting up a phi for the current location to initialize.
1911 llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
1912 llvm::BasicBlock *loopBB = createBasicBlock("arrayctor.loop");
1914 llvm::PHINode *cur = Builder.CreatePHI(arrayBegin->getType(), 2,
1916 cur->addIncoming(arrayBegin, entryBB);
1918 // Inside the loop body, emit the constructor call on the array element.
1920 // The alignment of the base, adjusted by the size of a single element,
1921 // provides a conservative estimate of the alignment of every element.
1922 // (This assumes we never start tracking offsetted alignments.)
1924 // Note that these are complete objects and so we don't need to
1925 // use the non-virtual size or alignment.
1926 QualType type = getContext().getTypeDeclType(ctor->getParent());
1927 CharUnits eltAlignment =
1928 arrayBase.getAlignment()
1929 .alignmentOfArrayElement(getContext().getTypeSizeInChars(type));
1930 Address curAddr = Address(cur, eltAlignment);
1932 // Zero initialize the storage, if requested.
1934 EmitNullInitialization(curAddr, type);
1936 // C++ [class.temporary]p4:
1937 // There are two contexts in which temporaries are destroyed at a different
1938 // point than the end of the full-expression. The first context is when a
1939 // default constructor is called to initialize an element of an array.
1940 // If the constructor has one or more default arguments, the destruction of
1941 // every temporary created in a default argument expression is sequenced
1942 // before the construction of the next array element, if any.
1945 RunCleanupsScope Scope(*this);
1947 // Evaluate the constructor and its arguments in a regular
1948 // partial-destroy cleanup.
1949 if (getLangOpts().Exceptions &&
1950 !ctor->getParent()->hasTrivialDestructor()) {
1951 Destroyer *destroyer = destroyCXXObject;
1952 pushRegularPartialArrayCleanup(arrayBegin, cur, type, eltAlignment,
1956 EmitCXXConstructorCall(ctor, Ctor_Complete, /*ForVirtualBase=*/false,
1957 /*Delegating=*/false, curAddr, E);
1960 // Go to the next element.
1962 Builder.CreateInBoundsGEP(cur, llvm::ConstantInt::get(SizeTy, 1),
1964 cur->addIncoming(next, Builder.GetInsertBlock());
1966 // Check whether that's the end of the loop.
1967 llvm::Value *done = Builder.CreateICmpEQ(next, arrayEnd, "arrayctor.done");
1968 llvm::BasicBlock *contBB = createBasicBlock("arrayctor.cont");
1969 Builder.CreateCondBr(done, contBB, loopBB);
1971 // Patch the earlier check to skip over the loop.
1972 if (zeroCheckBranch) zeroCheckBranch->setSuccessor(0, contBB);
1977 void CodeGenFunction::destroyCXXObject(CodeGenFunction &CGF,
1980 const RecordType *rtype = type->castAs<RecordType>();
1981 const CXXRecordDecl *record = cast<CXXRecordDecl>(rtype->getDecl());
1982 const CXXDestructorDecl *dtor = record->getDestructor();
1983 assert(!dtor->isTrivial());
1984 CGF.EmitCXXDestructorCall(dtor, Dtor_Complete, /*for vbase*/ false,
1985 /*Delegating=*/false, addr);
1988 void CodeGenFunction::EmitCXXConstructorCall(const CXXConstructorDecl *D,
1990 bool ForVirtualBase,
1991 bool Delegating, Address This,
1992 const CXXConstructExpr *E) {
1995 // Push the this ptr.
1996 Args.add(RValue::get(This.getPointer()), D->getThisType(getContext()));
1998 // If this is a trivial constructor, emit a memcpy now before we lose
1999 // the alignment information on the argument.
2000 // FIXME: It would be better to preserve alignment information into CallArg.
2001 if (isMemcpyEquivalentSpecialMember(D)) {
2002 assert(E->getNumArgs() == 1 && "unexpected argcount for trivial ctor");
2004 const Expr *Arg = E->getArg(0);
2005 QualType SrcTy = Arg->getType();
2006 Address Src = EmitLValue(Arg).getAddress();
2007 QualType DestTy = getContext().getTypeDeclType(D->getParent());
2008 EmitAggregateCopyCtor(This, Src, DestTy, SrcTy);
2012 // Add the rest of the user-supplied arguments.
2013 const FunctionProtoType *FPT = D->getType()->castAs<FunctionProtoType>();
2014 EvaluationOrder Order = E->isListInitialization()
2015 ? EvaluationOrder::ForceLeftToRight
2016 : EvaluationOrder::Default;
2017 EmitCallArgs(Args, FPT, E->arguments(), E->getConstructor(),
2018 /*ParamsToSkip*/ 0, Order);
2020 EmitCXXConstructorCall(D, Type, ForVirtualBase, Delegating, This, Args);
2023 static bool canEmitDelegateCallArgs(CodeGenFunction &CGF,
2024 const CXXConstructorDecl *Ctor,
2025 CXXCtorType Type, CallArgList &Args) {
2026 // We can't forward a variadic call.
2027 if (Ctor->isVariadic())
2030 if (CGF.getTarget().getCXXABI().areArgsDestroyedLeftToRightInCallee()) {
2031 // If the parameters are callee-cleanup, it's not safe to forward.
2032 for (auto *P : Ctor->parameters())
2033 if (P->getType().isDestructedType())
2036 // Likewise if they're inalloca.
2037 const CGFunctionInfo &Info =
2038 CGF.CGM.getTypes().arrangeCXXConstructorCall(Args, Ctor, Type, 0, 0);
2039 if (Info.usesInAlloca())
2043 // Anything else should be OK.
2047 void CodeGenFunction::EmitCXXConstructorCall(const CXXConstructorDecl *D,
2049 bool ForVirtualBase,
2052 CallArgList &Args) {
2053 const CXXRecordDecl *ClassDecl = D->getParent();
2055 // C++11 [class.mfct.non-static]p2:
2056 // If a non-static member function of a class X is called for an object that
2057 // is not of type X, or of a type derived from X, the behavior is undefined.
2058 // FIXME: Provide a source location here.
2059 EmitTypeCheck(CodeGenFunction::TCK_ConstructorCall, SourceLocation(),
2060 This.getPointer(), getContext().getRecordType(ClassDecl));
2062 if (D->isTrivial() && D->isDefaultConstructor()) {
2063 assert(Args.size() == 1 && "trivial default ctor with args");
2067 // If this is a trivial constructor, just emit what's needed. If this is a
2068 // union copy constructor, we must emit a memcpy, because the AST does not
2070 if (isMemcpyEquivalentSpecialMember(D)) {
2071 assert(Args.size() == 2 && "unexpected argcount for trivial ctor");
2073 QualType SrcTy = D->getParamDecl(0)->getType().getNonReferenceType();
2074 Address Src(Args[1].RV.getScalarVal(), getNaturalTypeAlignment(SrcTy));
2075 QualType DestTy = getContext().getTypeDeclType(ClassDecl);
2076 EmitAggregateCopyCtor(This, Src, DestTy, SrcTy);
2080 bool PassPrototypeArgs = true;
2081 // Check whether we can actually emit the constructor before trying to do so.
2082 if (auto Inherited = D->getInheritedConstructor()) {
2083 PassPrototypeArgs = getTypes().inheritingCtorHasParams(Inherited, Type);
2084 if (PassPrototypeArgs && !canEmitDelegateCallArgs(*this, D, Type, Args)) {
2085 EmitInlinedInheritingCXXConstructorCall(D, Type, ForVirtualBase,
2091 // Insert any ABI-specific implicit constructor arguments.
2092 CGCXXABI::AddedStructorArgs ExtraArgs =
2093 CGM.getCXXABI().addImplicitConstructorArgs(*this, D, Type, ForVirtualBase,
2097 llvm::Constant *CalleePtr =
2098 CGM.getAddrOfCXXStructor(D, getFromCtorType(Type));
2099 const CGFunctionInfo &Info = CGM.getTypes().arrangeCXXConstructorCall(
2100 Args, D, Type, ExtraArgs.Prefix, ExtraArgs.Suffix, PassPrototypeArgs);
2101 CGCallee Callee = CGCallee::forDirect(CalleePtr, D);
2102 EmitCall(Info, Callee, ReturnValueSlot(), Args);
2104 // Generate vtable assumptions if we're constructing a complete object
2105 // with a vtable. We don't do this for base subobjects for two reasons:
2106 // first, it's incorrect for classes with virtual bases, and second, we're
2107 // about to overwrite the vptrs anyway.
2108 // We also have to make sure if we can refer to vtable:
2109 // - Otherwise we can refer to vtable if it's safe to speculatively emit.
2110 // FIXME: If vtable is used by ctor/dtor, or if vtable is external and we are
2111 // sure that definition of vtable is not hidden,
2112 // then we are always safe to refer to it.
2113 // FIXME: It looks like InstCombine is very inefficient on dealing with
2114 // assumes. Make assumption loads require -fstrict-vtable-pointers temporarily.
2115 if (CGM.getCodeGenOpts().OptimizationLevel > 0 &&
2116 ClassDecl->isDynamicClass() && Type != Ctor_Base &&
2117 CGM.getCXXABI().canSpeculativelyEmitVTable(ClassDecl) &&
2118 CGM.getCodeGenOpts().StrictVTablePointers)
2119 EmitVTableAssumptionLoads(ClassDecl, This);
2122 void CodeGenFunction::EmitInheritedCXXConstructorCall(
2123 const CXXConstructorDecl *D, bool ForVirtualBase, Address This,
2124 bool InheritedFromVBase, const CXXInheritedCtorInitExpr *E) {
2126 CallArg ThisArg(RValue::get(This.getPointer()), D->getThisType(getContext()),
2127 /*NeedsCopy=*/false);
2129 // Forward the parameters.
2130 if (InheritedFromVBase &&
2131 CGM.getTarget().getCXXABI().hasConstructorVariants()) {
2132 // Nothing to do; this construction is not responsible for constructing
2133 // the base class containing the inherited constructor.
2134 // FIXME: Can we just pass undef's for the remaining arguments if we don't
2135 // have constructor variants?
2136 Args.push_back(ThisArg);
2137 } else if (!CXXInheritedCtorInitExprArgs.empty()) {
2138 // The inheriting constructor was inlined; just inject its arguments.
2139 assert(CXXInheritedCtorInitExprArgs.size() >= D->getNumParams() &&
2140 "wrong number of parameters for inherited constructor call");
2141 Args = CXXInheritedCtorInitExprArgs;
2144 // The inheriting constructor was not inlined. Emit delegating arguments.
2145 Args.push_back(ThisArg);
2146 const auto *OuterCtor = cast<CXXConstructorDecl>(CurCodeDecl);
2147 assert(OuterCtor->getNumParams() == D->getNumParams());
2148 assert(!OuterCtor->isVariadic() && "should have been inlined");
2150 for (const auto *Param : OuterCtor->parameters()) {
2151 assert(getContext().hasSameUnqualifiedType(
2152 OuterCtor->getParamDecl(Param->getFunctionScopeIndex())->getType(),
2154 EmitDelegateCallArg(Args, Param, E->getLocation());
2156 // Forward __attribute__(pass_object_size).
2157 if (Param->hasAttr<PassObjectSizeAttr>()) {
2158 auto *POSParam = SizeArguments[Param];
2159 assert(POSParam && "missing pass_object_size value for forwarding");
2160 EmitDelegateCallArg(Args, POSParam, E->getLocation());
2165 EmitCXXConstructorCall(D, Ctor_Base, ForVirtualBase, /*Delegating*/false,
2169 void CodeGenFunction::EmitInlinedInheritingCXXConstructorCall(
2170 const CXXConstructorDecl *Ctor, CXXCtorType CtorType, bool ForVirtualBase,
2171 bool Delegating, CallArgList &Args) {
2172 GlobalDecl GD(Ctor, CtorType);
2173 InlinedInheritingConstructorScope Scope(*this, GD);
2174 ApplyInlineDebugLocation DebugScope(*this, GD);
2176 // Save the arguments to be passed to the inherited constructor.
2177 CXXInheritedCtorInitExprArgs = Args;
2179 FunctionArgList Params;
2180 QualType RetType = BuildFunctionArgList(CurGD, Params);
2183 // Insert any ABI-specific implicit constructor arguments.
2184 CGM.getCXXABI().addImplicitConstructorArgs(*this, Ctor, CtorType,
2185 ForVirtualBase, Delegating, Args);
2187 // Emit a simplified prolog. We only need to emit the implicit params.
2188 assert(Args.size() >= Params.size() && "too few arguments for call");
2189 for (unsigned I = 0, N = Args.size(); I != N; ++I) {
2190 if (I < Params.size() && isa<ImplicitParamDecl>(Params[I])) {
2191 const RValue &RV = Args[I].RV;
2192 assert(!RV.isComplex() && "complex indirect params not supported");
2193 ParamValue Val = RV.isScalar()
2194 ? ParamValue::forDirect(RV.getScalarVal())
2195 : ParamValue::forIndirect(RV.getAggregateAddress());
2196 EmitParmDecl(*Params[I], Val, I + 1);
2200 // Create a return value slot if the ABI implementation wants one.
2201 // FIXME: This is dumb, we should ask the ABI not to try to set the return
2203 if (!RetType->isVoidType())
2204 ReturnValue = CreateIRTemp(RetType, "retval.inhctor");
2206 CGM.getCXXABI().EmitInstanceFunctionProlog(*this);
2207 CXXThisValue = CXXABIThisValue;
2209 // Directly emit the constructor initializers.
2210 EmitCtorPrologue(Ctor, CtorType, Params);
2213 void CodeGenFunction::EmitVTableAssumptionLoad(const VPtr &Vptr, Address This) {
2214 llvm::Value *VTableGlobal =
2215 CGM.getCXXABI().getVTableAddressPoint(Vptr.Base, Vptr.VTableClass);
2219 // We can just use the base offset in the complete class.
2220 CharUnits NonVirtualOffset = Vptr.Base.getBaseOffset();
2222 if (!NonVirtualOffset.isZero())
2224 ApplyNonVirtualAndVirtualOffset(*this, This, NonVirtualOffset, nullptr,
2225 Vptr.VTableClass, Vptr.NearestVBase);
2227 llvm::Value *VPtrValue =
2228 GetVTablePtr(This, VTableGlobal->getType(), Vptr.VTableClass);
2230 Builder.CreateICmpEQ(VPtrValue, VTableGlobal, "cmp.vtables");
2231 Builder.CreateAssumption(Cmp);
2234 void CodeGenFunction::EmitVTableAssumptionLoads(const CXXRecordDecl *ClassDecl,
2236 if (CGM.getCXXABI().doStructorsInitializeVPtrs(ClassDecl))
2237 for (const VPtr &Vptr : getVTablePointers(ClassDecl))
2238 EmitVTableAssumptionLoad(Vptr, This);
2242 CodeGenFunction::EmitSynthesizedCXXCopyCtorCall(const CXXConstructorDecl *D,
2243 Address This, Address Src,
2244 const CXXConstructExpr *E) {
2245 const FunctionProtoType *FPT = D->getType()->castAs<FunctionProtoType>();
2249 // Push the this ptr.
2250 Args.add(RValue::get(This.getPointer()), D->getThisType(getContext()));
2252 // Push the src ptr.
2253 QualType QT = *(FPT->param_type_begin());
2254 llvm::Type *t = CGM.getTypes().ConvertType(QT);
2255 Src = Builder.CreateBitCast(Src, t);
2256 Args.add(RValue::get(Src.getPointer()), QT);
2258 // Skip over first argument (Src).
2259 EmitCallArgs(Args, FPT, drop_begin(E->arguments(), 1), E->getConstructor(),
2260 /*ParamsToSkip*/ 1);
2262 EmitCXXConstructorCall(D, Ctor_Complete, false, false, This, Args);
2266 CodeGenFunction::EmitDelegateCXXConstructorCall(const CXXConstructorDecl *Ctor,
2267 CXXCtorType CtorType,
2268 const FunctionArgList &Args,
2269 SourceLocation Loc) {
2270 CallArgList DelegateArgs;
2272 FunctionArgList::const_iterator I = Args.begin(), E = Args.end();
2273 assert(I != E && "no parameters to constructor");
2276 Address This = LoadCXXThisAddress();
2277 DelegateArgs.add(RValue::get(This.getPointer()), (*I)->getType());
2280 // FIXME: The location of the VTT parameter in the parameter list is
2281 // specific to the Itanium ABI and shouldn't be hardcoded here.
2282 if (CGM.getCXXABI().NeedsVTTParameter(CurGD)) {
2283 assert(I != E && "cannot skip vtt parameter, already done with args");
2284 assert((*I)->getType()->isPointerType() &&
2285 "skipping parameter not of vtt type");
2289 // Explicit arguments.
2290 for (; I != E; ++I) {
2291 const VarDecl *param = *I;
2292 // FIXME: per-argument source location
2293 EmitDelegateCallArg(DelegateArgs, param, Loc);
2296 EmitCXXConstructorCall(Ctor, CtorType, /*ForVirtualBase=*/false,
2297 /*Delegating=*/true, This, DelegateArgs);
2301 struct CallDelegatingCtorDtor final : EHScopeStack::Cleanup {
2302 const CXXDestructorDecl *Dtor;
2306 CallDelegatingCtorDtor(const CXXDestructorDecl *D, Address Addr,
2308 : Dtor(D), Addr(Addr), Type(Type) {}
2310 void Emit(CodeGenFunction &CGF, Flags flags) override {
2311 CGF.EmitCXXDestructorCall(Dtor, Type, /*ForVirtualBase=*/false,
2312 /*Delegating=*/true, Addr);
2315 } // end anonymous namespace
2318 CodeGenFunction::EmitDelegatingCXXConstructorCall(const CXXConstructorDecl *Ctor,
2319 const FunctionArgList &Args) {
2320 assert(Ctor->isDelegatingConstructor());
2322 Address ThisPtr = LoadCXXThisAddress();
2324 AggValueSlot AggSlot =
2325 AggValueSlot::forAddr(ThisPtr, Qualifiers(),
2326 AggValueSlot::IsDestructed,
2327 AggValueSlot::DoesNotNeedGCBarriers,
2328 AggValueSlot::IsNotAliased);
2330 EmitAggExpr(Ctor->init_begin()[0]->getInit(), AggSlot);
2332 const CXXRecordDecl *ClassDecl = Ctor->getParent();
2333 if (CGM.getLangOpts().Exceptions && !ClassDecl->hasTrivialDestructor()) {
2335 CurGD.getCtorType() == Ctor_Complete ? Dtor_Complete : Dtor_Base;
2337 EHStack.pushCleanup<CallDelegatingCtorDtor>(EHCleanup,
2338 ClassDecl->getDestructor(),
2343 void CodeGenFunction::EmitCXXDestructorCall(const CXXDestructorDecl *DD,
2345 bool ForVirtualBase,
2348 CGM.getCXXABI().EmitDestructorCall(*this, DD, Type, ForVirtualBase,
2353 struct CallLocalDtor final : EHScopeStack::Cleanup {
2354 const CXXDestructorDecl *Dtor;
2357 CallLocalDtor(const CXXDestructorDecl *D, Address Addr)
2358 : Dtor(D), Addr(Addr) {}
2360 void Emit(CodeGenFunction &CGF, Flags flags) override {
2361 CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
2362 /*ForVirtualBase=*/false,
2363 /*Delegating=*/false, Addr);
2366 } // end anonymous namespace
2368 void CodeGenFunction::PushDestructorCleanup(const CXXDestructorDecl *D,
2370 EHStack.pushCleanup<CallLocalDtor>(NormalAndEHCleanup, D, Addr);
2373 void CodeGenFunction::PushDestructorCleanup(QualType T, Address Addr) {
2374 CXXRecordDecl *ClassDecl = T->getAsCXXRecordDecl();
2375 if (!ClassDecl) return;
2376 if (ClassDecl->hasTrivialDestructor()) return;
2378 const CXXDestructorDecl *D = ClassDecl->getDestructor();
2379 assert(D && D->isUsed() && "destructor not marked as used!");
2380 PushDestructorCleanup(D, Addr);
2383 void CodeGenFunction::InitializeVTablePointer(const VPtr &Vptr) {
2384 // Compute the address point.
2385 llvm::Value *VTableAddressPoint =
2386 CGM.getCXXABI().getVTableAddressPointInStructor(
2387 *this, Vptr.VTableClass, Vptr.Base, Vptr.NearestVBase);
2389 if (!VTableAddressPoint)
2392 // Compute where to store the address point.
2393 llvm::Value *VirtualOffset = nullptr;
2394 CharUnits NonVirtualOffset = CharUnits::Zero();
2396 if (CGM.getCXXABI().isVirtualOffsetNeededForVTableField(*this, Vptr)) {
2397 // We need to use the virtual base offset offset because the virtual base
2398 // might have a different offset in the most derived class.
2400 VirtualOffset = CGM.getCXXABI().GetVirtualBaseClassOffset(
2401 *this, LoadCXXThisAddress(), Vptr.VTableClass, Vptr.NearestVBase);
2402 NonVirtualOffset = Vptr.OffsetFromNearestVBase;
2404 // We can just use the base offset in the complete class.
2405 NonVirtualOffset = Vptr.Base.getBaseOffset();
2408 // Apply the offsets.
2409 Address VTableField = LoadCXXThisAddress();
2411 if (!NonVirtualOffset.isZero() || VirtualOffset)
2412 VTableField = ApplyNonVirtualAndVirtualOffset(
2413 *this, VTableField, NonVirtualOffset, VirtualOffset, Vptr.VTableClass,
2416 // Finally, store the address point. Use the same LLVM types as the field to
2417 // support optimization.
2418 llvm::Type *VTablePtrTy =
2419 llvm::FunctionType::get(CGM.Int32Ty, /*isVarArg=*/true)
2422 VTableField = Builder.CreateBitCast(VTableField, VTablePtrTy->getPointerTo());
2423 VTableAddressPoint = Builder.CreateBitCast(VTableAddressPoint, VTablePtrTy);
2425 llvm::StoreInst *Store = Builder.CreateStore(VTableAddressPoint, VTableField);
2426 TBAAAccessInfo TBAAInfo = CGM.getTBAAVTablePtrAccessInfo(VTablePtrTy);
2427 CGM.DecorateInstructionWithTBAA(Store, TBAAInfo);
2428 if (CGM.getCodeGenOpts().OptimizationLevel > 0 &&
2429 CGM.getCodeGenOpts().StrictVTablePointers)
2430 CGM.DecorateInstructionWithInvariantGroup(Store, Vptr.VTableClass);
2433 CodeGenFunction::VPtrsVector
2434 CodeGenFunction::getVTablePointers(const CXXRecordDecl *VTableClass) {
2435 CodeGenFunction::VPtrsVector VPtrsResult;
2436 VisitedVirtualBasesSetTy VBases;
2437 getVTablePointers(BaseSubobject(VTableClass, CharUnits::Zero()),
2438 /*NearestVBase=*/nullptr,
2439 /*OffsetFromNearestVBase=*/CharUnits::Zero(),
2440 /*BaseIsNonVirtualPrimaryBase=*/false, VTableClass, VBases,
2445 void CodeGenFunction::getVTablePointers(BaseSubobject Base,
2446 const CXXRecordDecl *NearestVBase,
2447 CharUnits OffsetFromNearestVBase,
2448 bool BaseIsNonVirtualPrimaryBase,
2449 const CXXRecordDecl *VTableClass,
2450 VisitedVirtualBasesSetTy &VBases,
2451 VPtrsVector &Vptrs) {
2452 // If this base is a non-virtual primary base the address point has already
2454 if (!BaseIsNonVirtualPrimaryBase) {
2455 // Initialize the vtable pointer for this base.
2456 VPtr Vptr = {Base, NearestVBase, OffsetFromNearestVBase, VTableClass};
2457 Vptrs.push_back(Vptr);
2460 const CXXRecordDecl *RD = Base.getBase();
2463 for (const auto &I : RD->bases()) {
2464 CXXRecordDecl *BaseDecl
2465 = cast<CXXRecordDecl>(I.getType()->getAs<RecordType>()->getDecl());
2467 // Ignore classes without a vtable.
2468 if (!BaseDecl->isDynamicClass())
2471 CharUnits BaseOffset;
2472 CharUnits BaseOffsetFromNearestVBase;
2473 bool BaseDeclIsNonVirtualPrimaryBase;
2475 if (I.isVirtual()) {
2476 // Check if we've visited this virtual base before.
2477 if (!VBases.insert(BaseDecl).second)
2480 const ASTRecordLayout &Layout =
2481 getContext().getASTRecordLayout(VTableClass);
2483 BaseOffset = Layout.getVBaseClassOffset(BaseDecl);
2484 BaseOffsetFromNearestVBase = CharUnits::Zero();
2485 BaseDeclIsNonVirtualPrimaryBase = false;
2487 const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
2489 BaseOffset = Base.getBaseOffset() + Layout.getBaseClassOffset(BaseDecl);
2490 BaseOffsetFromNearestVBase =
2491 OffsetFromNearestVBase + Layout.getBaseClassOffset(BaseDecl);
2492 BaseDeclIsNonVirtualPrimaryBase = Layout.getPrimaryBase() == BaseDecl;
2496 BaseSubobject(BaseDecl, BaseOffset),
2497 I.isVirtual() ? BaseDecl : NearestVBase, BaseOffsetFromNearestVBase,
2498 BaseDeclIsNonVirtualPrimaryBase, VTableClass, VBases, Vptrs);
2502 void CodeGenFunction::InitializeVTablePointers(const CXXRecordDecl *RD) {
2503 // Ignore classes without a vtable.
2504 if (!RD->isDynamicClass())
2507 // Initialize the vtable pointers for this class and all of its bases.
2508 if (CGM.getCXXABI().doStructorsInitializeVPtrs(RD))
2509 for (const VPtr &Vptr : getVTablePointers(RD))
2510 InitializeVTablePointer(Vptr);
2512 if (RD->getNumVBases())
2513 CGM.getCXXABI().initializeHiddenVirtualInheritanceMembers(*this, RD);
2516 llvm::Value *CodeGenFunction::GetVTablePtr(Address This,
2517 llvm::Type *VTableTy,
2518 const CXXRecordDecl *RD) {
2519 Address VTablePtrSrc = Builder.CreateElementBitCast(This, VTableTy);
2520 llvm::Instruction *VTable = Builder.CreateLoad(VTablePtrSrc, "vtable");
2521 TBAAAccessInfo TBAAInfo = CGM.getTBAAVTablePtrAccessInfo(VTableTy);
2522 CGM.DecorateInstructionWithTBAA(VTable, TBAAInfo);
2524 if (CGM.getCodeGenOpts().OptimizationLevel > 0 &&
2525 CGM.getCodeGenOpts().StrictVTablePointers)
2526 CGM.DecorateInstructionWithInvariantGroup(VTable, RD);
2531 // If a class has a single non-virtual base and does not introduce or override
2532 // virtual member functions or fields, it will have the same layout as its base.
2533 // This function returns the least derived such class.
2535 // Casting an instance of a base class to such a derived class is technically
2536 // undefined behavior, but it is a relatively common hack for introducing member
2537 // functions on class instances with specific properties (e.g. llvm::Operator)
2538 // that works under most compilers and should not have security implications, so
2539 // we allow it by default. It can be disabled with -fsanitize=cfi-cast-strict.
2540 static const CXXRecordDecl *
2541 LeastDerivedClassWithSameLayout(const CXXRecordDecl *RD) {
2542 if (!RD->field_empty())
2545 if (RD->getNumVBases() != 0)
2548 if (RD->getNumBases() != 1)
2551 for (const CXXMethodDecl *MD : RD->methods()) {
2552 if (MD->isVirtual()) {
2553 // Virtual member functions are only ok if they are implicit destructors
2554 // because the implicit destructor will have the same semantics as the
2555 // base class's destructor if no fields are added.
2556 if (isa<CXXDestructorDecl>(MD) && MD->isImplicit())
2562 return LeastDerivedClassWithSameLayout(
2563 RD->bases_begin()->getType()->getAsCXXRecordDecl());
2566 void CodeGenFunction::EmitTypeMetadataCodeForVCall(const CXXRecordDecl *RD,
2567 llvm::Value *VTable,
2568 SourceLocation Loc) {
2569 if (SanOpts.has(SanitizerKind::CFIVCall))
2570 EmitVTablePtrCheckForCall(RD, VTable, CodeGenFunction::CFITCK_VCall, Loc);
2571 else if (CGM.getCodeGenOpts().WholeProgramVTables &&
2572 CGM.HasHiddenLTOVisibility(RD)) {
2573 llvm::Metadata *MD =
2574 CGM.CreateMetadataIdentifierForType(QualType(RD->getTypeForDecl(), 0));
2575 llvm::Value *TypeId =
2576 llvm::MetadataAsValue::get(CGM.getLLVMContext(), MD);
2578 llvm::Value *CastedVTable = Builder.CreateBitCast(VTable, Int8PtrTy);
2579 llvm::Value *TypeTest =
2580 Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::type_test),
2581 {CastedVTable, TypeId});
2582 Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::assume), TypeTest);
2586 void CodeGenFunction::EmitVTablePtrCheckForCall(const CXXRecordDecl *RD,
2587 llvm::Value *VTable,
2588 CFITypeCheckKind TCK,
2589 SourceLocation Loc) {
2590 if (!SanOpts.has(SanitizerKind::CFICastStrict))
2591 RD = LeastDerivedClassWithSameLayout(RD);
2593 EmitVTablePtrCheck(RD, VTable, TCK, Loc);
2596 void CodeGenFunction::EmitVTablePtrCheckForCast(QualType T,
2597 llvm::Value *Derived,
2599 CFITypeCheckKind TCK,
2600 SourceLocation Loc) {
2601 if (!getLangOpts().CPlusPlus)
2604 auto *ClassTy = T->getAs<RecordType>();
2608 const CXXRecordDecl *ClassDecl = cast<CXXRecordDecl>(ClassTy->getDecl());
2610 if (!ClassDecl->isCompleteDefinition() || !ClassDecl->isDynamicClass())
2613 if (!SanOpts.has(SanitizerKind::CFICastStrict))
2614 ClassDecl = LeastDerivedClassWithSameLayout(ClassDecl);
2616 llvm::BasicBlock *ContBlock = nullptr;
2619 llvm::Value *DerivedNotNull =
2620 Builder.CreateIsNotNull(Derived, "cast.nonnull");
2622 llvm::BasicBlock *CheckBlock = createBasicBlock("cast.check");
2623 ContBlock = createBasicBlock("cast.cont");
2625 Builder.CreateCondBr(DerivedNotNull, CheckBlock, ContBlock);
2627 EmitBlock(CheckBlock);
2630 llvm::Value *VTable;
2631 std::tie(VTable, ClassDecl) = CGM.getCXXABI().LoadVTablePtr(
2632 *this, Address(Derived, getPointerAlign()), ClassDecl);
2634 EmitVTablePtrCheck(ClassDecl, VTable, TCK, Loc);
2637 Builder.CreateBr(ContBlock);
2638 EmitBlock(ContBlock);
2642 void CodeGenFunction::EmitVTablePtrCheck(const CXXRecordDecl *RD,
2643 llvm::Value *VTable,
2644 CFITypeCheckKind TCK,
2645 SourceLocation Loc) {
2646 if (!CGM.getCodeGenOpts().SanitizeCfiCrossDso &&
2647 !CGM.HasHiddenLTOVisibility(RD))
2651 llvm::SanitizerStatKind SSK;
2654 M = SanitizerKind::CFIVCall;
2655 SSK = llvm::SanStat_CFI_VCall;
2658 M = SanitizerKind::CFINVCall;
2659 SSK = llvm::SanStat_CFI_NVCall;
2661 case CFITCK_DerivedCast:
2662 M = SanitizerKind::CFIDerivedCast;
2663 SSK = llvm::SanStat_CFI_DerivedCast;
2665 case CFITCK_UnrelatedCast:
2666 M = SanitizerKind::CFIUnrelatedCast;
2667 SSK = llvm::SanStat_CFI_UnrelatedCast;
2670 llvm_unreachable("not expecting CFITCK_ICall");
2673 std::string TypeName = RD->getQualifiedNameAsString();
2674 if (getContext().getSanitizerBlacklist().isBlacklistedType(M, TypeName))
2677 SanitizerScope SanScope(this);
2678 EmitSanitizerStatReport(SSK);
2680 llvm::Metadata *MD =
2681 CGM.CreateMetadataIdentifierForType(QualType(RD->getTypeForDecl(), 0));
2682 llvm::Value *TypeId = llvm::MetadataAsValue::get(getLLVMContext(), MD);
2684 llvm::Value *CastedVTable = Builder.CreateBitCast(VTable, Int8PtrTy);
2685 llvm::Value *TypeTest = Builder.CreateCall(
2686 CGM.getIntrinsic(llvm::Intrinsic::type_test), {CastedVTable, TypeId});
2688 llvm::Constant *StaticData[] = {
2689 llvm::ConstantInt::get(Int8Ty, TCK),
2690 EmitCheckSourceLocation(Loc),
2691 EmitCheckTypeDescriptor(QualType(RD->getTypeForDecl(), 0)),
2694 auto CrossDsoTypeId = CGM.CreateCrossDsoCfiTypeId(MD);
2695 if (CGM.getCodeGenOpts().SanitizeCfiCrossDso && CrossDsoTypeId) {
2696 EmitCfiSlowPathCheck(M, TypeTest, CrossDsoTypeId, CastedVTable, StaticData);
2700 if (CGM.getCodeGenOpts().SanitizeTrap.has(M)) {
2701 EmitTrapCheck(TypeTest);
2705 llvm::Value *AllVtables = llvm::MetadataAsValue::get(
2706 CGM.getLLVMContext(),
2707 llvm::MDString::get(CGM.getLLVMContext(), "all-vtables"));
2708 llvm::Value *ValidVtable = Builder.CreateCall(
2709 CGM.getIntrinsic(llvm::Intrinsic::type_test), {CastedVTable, AllVtables});
2710 EmitCheck(std::make_pair(TypeTest, M), SanitizerHandler::CFICheckFail,
2711 StaticData, {CastedVTable, ValidVtable});
2714 bool CodeGenFunction::ShouldEmitVTableTypeCheckedLoad(const CXXRecordDecl *RD) {
2715 if (!CGM.getCodeGenOpts().WholeProgramVTables ||
2716 !SanOpts.has(SanitizerKind::CFIVCall) ||
2717 !CGM.getCodeGenOpts().SanitizeTrap.has(SanitizerKind::CFIVCall) ||
2718 !CGM.HasHiddenLTOVisibility(RD))
2721 std::string TypeName = RD->getQualifiedNameAsString();
2722 return !getContext().getSanitizerBlacklist().isBlacklistedType(
2723 SanitizerKind::CFIVCall, TypeName);
2726 llvm::Value *CodeGenFunction::EmitVTableTypeCheckedLoad(
2727 const CXXRecordDecl *RD, llvm::Value *VTable, uint64_t VTableByteOffset) {
2728 SanitizerScope SanScope(this);
2730 EmitSanitizerStatReport(llvm::SanStat_CFI_VCall);
2732 llvm::Metadata *MD =
2733 CGM.CreateMetadataIdentifierForType(QualType(RD->getTypeForDecl(), 0));
2734 llvm::Value *TypeId = llvm::MetadataAsValue::get(CGM.getLLVMContext(), MD);
2736 llvm::Value *CastedVTable = Builder.CreateBitCast(VTable, Int8PtrTy);
2737 llvm::Value *CheckedLoad = Builder.CreateCall(
2738 CGM.getIntrinsic(llvm::Intrinsic::type_checked_load),
2739 {CastedVTable, llvm::ConstantInt::get(Int32Ty, VTableByteOffset),
2741 llvm::Value *CheckResult = Builder.CreateExtractValue(CheckedLoad, 1);
2743 EmitCheck(std::make_pair(CheckResult, SanitizerKind::CFIVCall),
2744 SanitizerHandler::CFICheckFail, nullptr, nullptr);
2746 return Builder.CreateBitCast(
2747 Builder.CreateExtractValue(CheckedLoad, 0),
2748 cast<llvm::PointerType>(VTable->getType())->getElementType());
2751 void CodeGenFunction::EmitForwardingCallToLambda(
2752 const CXXMethodDecl *callOperator,
2753 CallArgList &callArgs) {
2754 // Get the address of the call operator.
2755 const CGFunctionInfo &calleeFnInfo =
2756 CGM.getTypes().arrangeCXXMethodDeclaration(callOperator);
2757 llvm::Constant *calleePtr =
2758 CGM.GetAddrOfFunction(GlobalDecl(callOperator),
2759 CGM.getTypes().GetFunctionType(calleeFnInfo));
2761 // Prepare the return slot.
2762 const FunctionProtoType *FPT =
2763 callOperator->getType()->castAs<FunctionProtoType>();
2764 QualType resultType = FPT->getReturnType();
2765 ReturnValueSlot returnSlot;
2766 if (!resultType->isVoidType() &&
2767 calleeFnInfo.getReturnInfo().getKind() == ABIArgInfo::Indirect &&
2768 !hasScalarEvaluationKind(calleeFnInfo.getReturnType()))
2769 returnSlot = ReturnValueSlot(ReturnValue, resultType.isVolatileQualified());
2771 // We don't need to separately arrange the call arguments because
2772 // the call can't be variadic anyway --- it's impossible to forward
2773 // variadic arguments.
2775 // Now emit our call.
2776 auto callee = CGCallee::forDirect(calleePtr, callOperator);
2777 RValue RV = EmitCall(calleeFnInfo, callee, returnSlot, callArgs);
2779 // If necessary, copy the returned value into the slot.
2780 if (!resultType->isVoidType() && returnSlot.isNull()) {
2781 if (getLangOpts().ObjCAutoRefCount && resultType->isObjCRetainableType()) {
2782 RV = RValue::get(EmitARCRetainAutoreleasedReturnValue(RV.getScalarVal()));
2784 EmitReturnOfRValue(RV, resultType);
2786 EmitBranchThroughCleanup(ReturnBlock);
2789 void CodeGenFunction::EmitLambdaBlockInvokeBody() {
2790 const BlockDecl *BD = BlockInfo->getBlockDecl();
2791 const VarDecl *variable = BD->capture_begin()->getVariable();
2792 const CXXRecordDecl *Lambda = variable->getType()->getAsCXXRecordDecl();
2793 const CXXMethodDecl *CallOp = Lambda->getLambdaCallOperator();
2795 if (CallOp->isVariadic()) {
2796 // FIXME: Making this work correctly is nasty because it requires either
2797 // cloning the body of the call operator or making the call operator
2799 CGM.ErrorUnsupported(CurCodeDecl, "lambda conversion to variadic function");
2803 // Start building arguments for forwarding call
2804 CallArgList CallArgs;
2806 QualType ThisType = getContext().getPointerType(getContext().getRecordType(Lambda));
2807 Address ThisPtr = GetAddrOfBlockDecl(variable, false);
2808 CallArgs.add(RValue::get(ThisPtr.getPointer()), ThisType);
2810 // Add the rest of the parameters.
2811 for (auto param : BD->parameters())
2812 EmitDelegateCallArg(CallArgs, param, param->getLocStart());
2814 assert(!Lambda->isGenericLambda() &&
2815 "generic lambda interconversion to block not implemented");
2816 EmitForwardingCallToLambda(CallOp, CallArgs);
2819 void CodeGenFunction::EmitLambdaDelegatingInvokeBody(const CXXMethodDecl *MD) {
2820 const CXXRecordDecl *Lambda = MD->getParent();
2822 // Start building arguments for forwarding call
2823 CallArgList CallArgs;
2825 QualType ThisType = getContext().getPointerType(getContext().getRecordType(Lambda));
2826 llvm::Value *ThisPtr = llvm::UndefValue::get(getTypes().ConvertType(ThisType));
2827 CallArgs.add(RValue::get(ThisPtr), ThisType);
2829 // Add the rest of the parameters.
2830 for (auto Param : MD->parameters())
2831 EmitDelegateCallArg(CallArgs, Param, Param->getLocStart());
2833 const CXXMethodDecl *CallOp = Lambda->getLambdaCallOperator();
2834 // For a generic lambda, find the corresponding call operator specialization
2835 // to which the call to the static-invoker shall be forwarded.
2836 if (Lambda->isGenericLambda()) {
2837 assert(MD->isFunctionTemplateSpecialization());
2838 const TemplateArgumentList *TAL = MD->getTemplateSpecializationArgs();
2839 FunctionTemplateDecl *CallOpTemplate = CallOp->getDescribedFunctionTemplate();
2840 void *InsertPos = nullptr;
2841 FunctionDecl *CorrespondingCallOpSpecialization =
2842 CallOpTemplate->findSpecialization(TAL->asArray(), InsertPos);
2843 assert(CorrespondingCallOpSpecialization);
2844 CallOp = cast<CXXMethodDecl>(CorrespondingCallOpSpecialization);
2846 EmitForwardingCallToLambda(CallOp, CallArgs);
2849 void CodeGenFunction::EmitLambdaStaticInvokeBody(const CXXMethodDecl *MD) {
2850 if (MD->isVariadic()) {
2851 // FIXME: Making this work correctly is nasty because it requires either
2852 // cloning the body of the call operator or making the call operator forward.
2853 CGM.ErrorUnsupported(MD, "lambda conversion to variadic function");
2857 EmitLambdaDelegatingInvokeBody(MD);