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.CreateInBoundsGEP(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(
560 AggValueSlot::IsDestructed,
561 AggValueSlot::DoesNotNeedGCBarriers,
562 AggValueSlot::IsNotAliased,
563 CGF.overlapForBaseInit(ClassDecl, BaseClassDecl, isBaseVirtual));
565 CGF.EmitAggExpr(BaseInit->getInit(), AggSlot);
567 if (CGF.CGM.getLangOpts().Exceptions &&
568 !BaseClassDecl->hasTrivialDestructor())
569 CGF.EHStack.pushCleanup<CallBaseDtor>(EHCleanup, BaseClassDecl,
573 static bool isMemcpyEquivalentSpecialMember(const CXXMethodDecl *D) {
574 auto *CD = dyn_cast<CXXConstructorDecl>(D);
575 if (!(CD && CD->isCopyOrMoveConstructor()) &&
576 !D->isCopyAssignmentOperator() && !D->isMoveAssignmentOperator())
579 // We can emit a memcpy for a trivial copy or move constructor/assignment.
580 if (D->isTrivial() && !D->getParent()->mayInsertExtraPadding())
583 // We *must* emit a memcpy for a defaulted union copy or move op.
584 if (D->getParent()->isUnion() && D->isDefaulted())
590 static void EmitLValueForAnyFieldInitialization(CodeGenFunction &CGF,
591 CXXCtorInitializer *MemberInit,
593 FieldDecl *Field = MemberInit->getAnyMember();
594 if (MemberInit->isIndirectMemberInitializer()) {
595 // If we are initializing an anonymous union field, drill down to the field.
596 IndirectFieldDecl *IndirectField = MemberInit->getIndirectMember();
597 for (const auto *I : IndirectField->chain())
598 LHS = CGF.EmitLValueForFieldInitialization(LHS, cast<FieldDecl>(I));
600 LHS = CGF.EmitLValueForFieldInitialization(LHS, Field);
604 static void EmitMemberInitializer(CodeGenFunction &CGF,
605 const CXXRecordDecl *ClassDecl,
606 CXXCtorInitializer *MemberInit,
607 const CXXConstructorDecl *Constructor,
608 FunctionArgList &Args) {
609 ApplyDebugLocation Loc(CGF, MemberInit->getSourceLocation());
610 assert(MemberInit->isAnyMemberInitializer() &&
611 "Must have member initializer!");
612 assert(MemberInit->getInit() && "Must have initializer!");
614 // non-static data member initializers.
615 FieldDecl *Field = MemberInit->getAnyMember();
616 QualType FieldType = Field->getType();
618 llvm::Value *ThisPtr = CGF.LoadCXXThis();
619 QualType RecordTy = CGF.getContext().getTypeDeclType(ClassDecl);
622 // If a base constructor is being emitted, create an LValue that has the
623 // non-virtual alignment.
624 if (CGF.CurGD.getCtorType() == Ctor_Base)
625 LHS = CGF.MakeNaturalAlignPointeeAddrLValue(ThisPtr, RecordTy);
627 LHS = CGF.MakeNaturalAlignAddrLValue(ThisPtr, RecordTy);
629 EmitLValueForAnyFieldInitialization(CGF, MemberInit, LHS);
631 // Special case: if we are in a copy or move constructor, and we are copying
632 // an array of PODs or classes with trivial copy constructors, ignore the
633 // AST and perform the copy we know is equivalent.
634 // FIXME: This is hacky at best... if we had a bit more explicit information
635 // in the AST, we could generalize it more easily.
636 const ConstantArrayType *Array
637 = CGF.getContext().getAsConstantArrayType(FieldType);
638 if (Array && Constructor->isDefaulted() &&
639 Constructor->isCopyOrMoveConstructor()) {
640 QualType BaseElementTy = CGF.getContext().getBaseElementType(Array);
641 CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(MemberInit->getInit());
642 if (BaseElementTy.isPODType(CGF.getContext()) ||
643 (CE && isMemcpyEquivalentSpecialMember(CE->getConstructor()))) {
644 unsigned SrcArgIndex =
645 CGF.CGM.getCXXABI().getSrcArgforCopyCtor(Constructor, Args);
647 = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(Args[SrcArgIndex]));
648 LValue ThisRHSLV = CGF.MakeNaturalAlignAddrLValue(SrcPtr, RecordTy);
649 LValue Src = CGF.EmitLValueForFieldInitialization(ThisRHSLV, Field);
651 // Copy the aggregate.
652 CGF.EmitAggregateCopy(LHS, Src, FieldType, CGF.overlapForFieldInit(Field),
653 LHS.isVolatileQualified());
654 // Ensure that we destroy the objects if an exception is thrown later in
656 QualType::DestructionKind dtorKind = FieldType.isDestructedType();
657 if (CGF.needsEHCleanup(dtorKind))
658 CGF.pushEHDestroy(dtorKind, LHS.getAddress(), FieldType);
663 CGF.EmitInitializerForField(Field, LHS, MemberInit->getInit());
666 void CodeGenFunction::EmitInitializerForField(FieldDecl *Field, LValue LHS,
668 QualType FieldType = Field->getType();
669 switch (getEvaluationKind(FieldType)) {
671 if (LHS.isSimple()) {
672 EmitExprAsInit(Init, Field, LHS, false);
674 RValue RHS = RValue::get(EmitScalarExpr(Init));
675 EmitStoreThroughLValue(RHS, LHS);
679 EmitComplexExprIntoLValue(Init, LHS, /*isInit*/ true);
681 case TEK_Aggregate: {
683 AggValueSlot::forLValue(
685 AggValueSlot::IsDestructed,
686 AggValueSlot::DoesNotNeedGCBarriers,
687 AggValueSlot::IsNotAliased,
688 overlapForFieldInit(Field),
689 AggValueSlot::IsNotZeroed,
690 // Checks are made by the code that calls constructor.
691 AggValueSlot::IsSanitizerChecked);
692 EmitAggExpr(Init, Slot);
697 // Ensure that we destroy this object if an exception is thrown
698 // later in the constructor.
699 QualType::DestructionKind dtorKind = FieldType.isDestructedType();
700 if (needsEHCleanup(dtorKind))
701 pushEHDestroy(dtorKind, LHS.getAddress(), FieldType);
704 /// Checks whether the given constructor is a valid subject for the
705 /// complete-to-base constructor delegation optimization, i.e.
706 /// emitting the complete constructor as a simple call to the base
708 bool CodeGenFunction::IsConstructorDelegationValid(
709 const CXXConstructorDecl *Ctor) {
711 // Currently we disable the optimization for classes with virtual
712 // bases because (1) the addresses of parameter variables need to be
713 // consistent across all initializers but (2) the delegate function
714 // call necessarily creates a second copy of the parameter variable.
716 // The limiting example (purely theoretical AFAIK):
717 // struct A { A(int &c) { c++; } };
718 // struct B : virtual A {
719 // B(int count) : A(count) { printf("%d\n", count); }
721 // ...although even this example could in principle be emitted as a
722 // delegation since the address of the parameter doesn't escape.
723 if (Ctor->getParent()->getNumVBases()) {
724 // TODO: white-list trivial vbase initializers. This case wouldn't
725 // be subject to the restrictions below.
727 // TODO: white-list cases where:
728 // - there are no non-reference parameters to the constructor
729 // - the initializers don't access any non-reference parameters
730 // - the initializers don't take the address of non-reference
733 // If we ever add any of the above cases, remember that:
734 // - function-try-blocks will always blacklist this optimization
735 // - we need to perform the constructor prologue and cleanup in
736 // EmitConstructorBody.
741 // We also disable the optimization for variadic functions because
742 // it's impossible to "re-pass" varargs.
743 if (Ctor->getType()->getAs<FunctionProtoType>()->isVariadic())
746 // FIXME: Decide if we can do a delegation of a delegating constructor.
747 if (Ctor->isDelegatingConstructor())
753 // Emit code in ctor (Prologue==true) or dtor (Prologue==false)
754 // to poison the extra field paddings inserted under
755 // -fsanitize-address-field-padding=1|2.
756 void CodeGenFunction::EmitAsanPrologueOrEpilogue(bool Prologue) {
757 ASTContext &Context = getContext();
758 const CXXRecordDecl *ClassDecl =
759 Prologue ? cast<CXXConstructorDecl>(CurGD.getDecl())->getParent()
760 : cast<CXXDestructorDecl>(CurGD.getDecl())->getParent();
761 if (!ClassDecl->mayInsertExtraPadding()) return;
763 struct SizeAndOffset {
768 unsigned PtrSize = CGM.getDataLayout().getPointerSizeInBits();
769 const ASTRecordLayout &Info = Context.getASTRecordLayout(ClassDecl);
771 // Populate sizes and offsets of fields.
772 SmallVector<SizeAndOffset, 16> SSV(Info.getFieldCount());
773 for (unsigned i = 0, e = Info.getFieldCount(); i != e; ++i)
775 Context.toCharUnitsFromBits(Info.getFieldOffset(i)).getQuantity();
777 size_t NumFields = 0;
778 for (const auto *Field : ClassDecl->fields()) {
779 const FieldDecl *D = Field;
780 std::pair<CharUnits, CharUnits> FieldInfo =
781 Context.getTypeInfoInChars(D->getType());
782 CharUnits FieldSize = FieldInfo.first;
783 assert(NumFields < SSV.size());
784 SSV[NumFields].Size = D->isBitField() ? 0 : FieldSize.getQuantity();
787 assert(NumFields == SSV.size());
788 if (SSV.size() <= 1) return;
790 // We will insert calls to __asan_* run-time functions.
791 // LLVM AddressSanitizer pass may decide to inline them later.
792 llvm::Type *Args[2] = {IntPtrTy, IntPtrTy};
793 llvm::FunctionType *FTy =
794 llvm::FunctionType::get(CGM.VoidTy, Args, false);
795 llvm::Constant *F = CGM.CreateRuntimeFunction(
796 FTy, Prologue ? "__asan_poison_intra_object_redzone"
797 : "__asan_unpoison_intra_object_redzone");
799 llvm::Value *ThisPtr = LoadCXXThis();
800 ThisPtr = Builder.CreatePtrToInt(ThisPtr, IntPtrTy);
801 uint64_t TypeSize = Info.getNonVirtualSize().getQuantity();
802 // For each field check if it has sufficient padding,
803 // if so (un)poison it with a call.
804 for (size_t i = 0; i < SSV.size(); i++) {
805 uint64_t AsanAlignment = 8;
806 uint64_t NextField = i == SSV.size() - 1 ? TypeSize : SSV[i + 1].Offset;
807 uint64_t PoisonSize = NextField - SSV[i].Offset - SSV[i].Size;
808 uint64_t EndOffset = SSV[i].Offset + SSV[i].Size;
809 if (PoisonSize < AsanAlignment || !SSV[i].Size ||
810 (NextField % AsanAlignment) != 0)
813 F, {Builder.CreateAdd(ThisPtr, Builder.getIntN(PtrSize, EndOffset)),
814 Builder.getIntN(PtrSize, PoisonSize)});
818 /// EmitConstructorBody - Emits the body of the current constructor.
819 void CodeGenFunction::EmitConstructorBody(FunctionArgList &Args) {
820 EmitAsanPrologueOrEpilogue(true);
821 const CXXConstructorDecl *Ctor = cast<CXXConstructorDecl>(CurGD.getDecl());
822 CXXCtorType CtorType = CurGD.getCtorType();
824 assert((CGM.getTarget().getCXXABI().hasConstructorVariants() ||
825 CtorType == Ctor_Complete) &&
826 "can only generate complete ctor for this ABI");
828 // Before we go any further, try the complete->base constructor
829 // delegation optimization.
830 if (CtorType == Ctor_Complete && IsConstructorDelegationValid(Ctor) &&
831 CGM.getTarget().getCXXABI().hasConstructorVariants()) {
832 EmitDelegateCXXConstructorCall(Ctor, Ctor_Base, Args, Ctor->getLocEnd());
836 const FunctionDecl *Definition = nullptr;
837 Stmt *Body = Ctor->getBody(Definition);
838 assert(Definition == Ctor && "emitting wrong constructor body");
840 // Enter the function-try-block before the constructor prologue if
842 bool IsTryBody = (Body && isa<CXXTryStmt>(Body));
844 EnterCXXTryStmt(*cast<CXXTryStmt>(Body), true);
846 incrementProfileCounter(Body);
848 RunCleanupsScope RunCleanups(*this);
850 // TODO: in restricted cases, we can emit the vbase initializers of
851 // a complete ctor and then delegate to the base ctor.
853 // Emit the constructor prologue, i.e. the base and member
855 EmitCtorPrologue(Ctor, CtorType, Args);
857 // Emit the body of the statement.
859 EmitStmt(cast<CXXTryStmt>(Body)->getTryBlock());
863 // Emit any cleanup blocks associated with the member or base
864 // initializers, which includes (along the exceptional path) the
865 // destructors for those members and bases that were fully
867 RunCleanups.ForceCleanup();
870 ExitCXXTryStmt(*cast<CXXTryStmt>(Body), true);
874 /// RAII object to indicate that codegen is copying the value representation
875 /// instead of the object representation. Useful when copying a struct or
876 /// class which has uninitialized members and we're only performing
877 /// lvalue-to-rvalue conversion on the object but not its members.
878 class CopyingValueRepresentation {
880 explicit CopyingValueRepresentation(CodeGenFunction &CGF)
881 : CGF(CGF), OldSanOpts(CGF.SanOpts) {
882 CGF.SanOpts.set(SanitizerKind::Bool, false);
883 CGF.SanOpts.set(SanitizerKind::Enum, false);
885 ~CopyingValueRepresentation() {
886 CGF.SanOpts = OldSanOpts;
889 CodeGenFunction &CGF;
890 SanitizerSet OldSanOpts;
892 } // end anonymous namespace
895 class FieldMemcpyizer {
897 FieldMemcpyizer(CodeGenFunction &CGF, const CXXRecordDecl *ClassDecl,
898 const VarDecl *SrcRec)
899 : CGF(CGF), ClassDecl(ClassDecl), SrcRec(SrcRec),
900 RecLayout(CGF.getContext().getASTRecordLayout(ClassDecl)),
901 FirstField(nullptr), LastField(nullptr), FirstFieldOffset(0),
902 LastFieldOffset(0), LastAddedFieldIndex(0) {}
904 bool isMemcpyableField(FieldDecl *F) const {
905 // Never memcpy fields when we are adding poisoned paddings.
906 if (CGF.getContext().getLangOpts().SanitizeAddressFieldPadding)
908 Qualifiers Qual = F->getType().getQualifiers();
909 if (Qual.hasVolatile() || Qual.hasObjCLifetime())
914 void addMemcpyableField(FieldDecl *F) {
921 CharUnits getMemcpySize(uint64_t FirstByteOffset) const {
922 ASTContext &Ctx = CGF.getContext();
923 unsigned LastFieldSize =
924 LastField->isBitField()
925 ? LastField->getBitWidthValue(Ctx)
927 Ctx.getTypeInfoDataSizeInChars(LastField->getType()).first);
928 uint64_t MemcpySizeBits = LastFieldOffset + LastFieldSize -
929 FirstByteOffset + Ctx.getCharWidth() - 1;
930 CharUnits MemcpySize = Ctx.toCharUnitsFromBits(MemcpySizeBits);
935 // Give the subclass a chance to bail out if it feels the memcpy isn't
936 // worth it (e.g. Hasn't aggregated enough data).
941 uint64_t FirstByteOffset;
942 if (FirstField->isBitField()) {
943 const CGRecordLayout &RL =
944 CGF.getTypes().getCGRecordLayout(FirstField->getParent());
945 const CGBitFieldInfo &BFInfo = RL.getBitFieldInfo(FirstField);
946 // FirstFieldOffset is not appropriate for bitfields,
947 // we need to use the storage offset instead.
948 FirstByteOffset = CGF.getContext().toBits(BFInfo.StorageOffset);
950 FirstByteOffset = FirstFieldOffset;
953 CharUnits MemcpySize = getMemcpySize(FirstByteOffset);
954 QualType RecordTy = CGF.getContext().getTypeDeclType(ClassDecl);
955 Address ThisPtr = CGF.LoadCXXThisAddress();
956 LValue DestLV = CGF.MakeAddrLValue(ThisPtr, RecordTy);
957 LValue Dest = CGF.EmitLValueForFieldInitialization(DestLV, FirstField);
958 llvm::Value *SrcPtr = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(SrcRec));
959 LValue SrcLV = CGF.MakeNaturalAlignAddrLValue(SrcPtr, RecordTy);
960 LValue Src = CGF.EmitLValueForFieldInitialization(SrcLV, FirstField);
962 emitMemcpyIR(Dest.isBitField() ? Dest.getBitFieldAddress() : Dest.getAddress(),
963 Src.isBitField() ? Src.getBitFieldAddress() : Src.getAddress(),
969 FirstField = nullptr;
973 CodeGenFunction &CGF;
974 const CXXRecordDecl *ClassDecl;
977 void emitMemcpyIR(Address DestPtr, Address SrcPtr, CharUnits Size) {
978 llvm::PointerType *DPT = DestPtr.getType();
980 llvm::Type::getInt8PtrTy(CGF.getLLVMContext(), DPT->getAddressSpace());
981 DestPtr = CGF.Builder.CreateBitCast(DestPtr, DBP);
983 llvm::PointerType *SPT = SrcPtr.getType();
985 llvm::Type::getInt8PtrTy(CGF.getLLVMContext(), SPT->getAddressSpace());
986 SrcPtr = CGF.Builder.CreateBitCast(SrcPtr, SBP);
988 CGF.Builder.CreateMemCpy(DestPtr, SrcPtr, Size.getQuantity());
991 void addInitialField(FieldDecl *F) {
994 FirstFieldOffset = RecLayout.getFieldOffset(F->getFieldIndex());
995 LastFieldOffset = FirstFieldOffset;
996 LastAddedFieldIndex = F->getFieldIndex();
999 void addNextField(FieldDecl *F) {
1000 // For the most part, the following invariant will hold:
1001 // F->getFieldIndex() == LastAddedFieldIndex + 1
1002 // The one exception is that Sema won't add a copy-initializer for an
1003 // unnamed bitfield, which will show up here as a gap in the sequence.
1004 assert(F->getFieldIndex() >= LastAddedFieldIndex + 1 &&
1005 "Cannot aggregate fields out of order.");
1006 LastAddedFieldIndex = F->getFieldIndex();
1008 // The 'first' and 'last' fields are chosen by offset, rather than field
1009 // index. This allows the code to support bitfields, as well as regular
1011 uint64_t FOffset = RecLayout.getFieldOffset(F->getFieldIndex());
1012 if (FOffset < FirstFieldOffset) {
1014 FirstFieldOffset = FOffset;
1015 } else if (FOffset > LastFieldOffset) {
1017 LastFieldOffset = FOffset;
1021 const VarDecl *SrcRec;
1022 const ASTRecordLayout &RecLayout;
1023 FieldDecl *FirstField;
1024 FieldDecl *LastField;
1025 uint64_t FirstFieldOffset, LastFieldOffset;
1026 unsigned LastAddedFieldIndex;
1029 class ConstructorMemcpyizer : public FieldMemcpyizer {
1031 /// Get source argument for copy constructor. Returns null if not a copy
1033 static const VarDecl *getTrivialCopySource(CodeGenFunction &CGF,
1034 const CXXConstructorDecl *CD,
1035 FunctionArgList &Args) {
1036 if (CD->isCopyOrMoveConstructor() && CD->isDefaulted())
1037 return Args[CGF.CGM.getCXXABI().getSrcArgforCopyCtor(CD, Args)];
1041 // Returns true if a CXXCtorInitializer represents a member initialization
1042 // that can be rolled into a memcpy.
1043 bool isMemberInitMemcpyable(CXXCtorInitializer *MemberInit) const {
1044 if (!MemcpyableCtor)
1046 FieldDecl *Field = MemberInit->getMember();
1047 assert(Field && "No field for member init.");
1048 QualType FieldType = Field->getType();
1049 CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(MemberInit->getInit());
1051 // Bail out on non-memcpyable, not-trivially-copyable members.
1052 if (!(CE && isMemcpyEquivalentSpecialMember(CE->getConstructor())) &&
1053 !(FieldType.isTriviallyCopyableType(CGF.getContext()) ||
1054 FieldType->isReferenceType()))
1057 // Bail out on volatile fields.
1058 if (!isMemcpyableField(Field))
1061 // Otherwise we're good.
1066 ConstructorMemcpyizer(CodeGenFunction &CGF, const CXXConstructorDecl *CD,
1067 FunctionArgList &Args)
1068 : FieldMemcpyizer(CGF, CD->getParent(), getTrivialCopySource(CGF, CD, Args)),
1069 ConstructorDecl(CD),
1070 MemcpyableCtor(CD->isDefaulted() &&
1071 CD->isCopyOrMoveConstructor() &&
1072 CGF.getLangOpts().getGC() == LangOptions::NonGC),
1075 void addMemberInitializer(CXXCtorInitializer *MemberInit) {
1076 if (isMemberInitMemcpyable(MemberInit)) {
1077 AggregatedInits.push_back(MemberInit);
1078 addMemcpyableField(MemberInit->getMember());
1080 emitAggregatedInits();
1081 EmitMemberInitializer(CGF, ConstructorDecl->getParent(), MemberInit,
1082 ConstructorDecl, Args);
1086 void emitAggregatedInits() {
1087 if (AggregatedInits.size() <= 1) {
1088 // This memcpy is too small to be worthwhile. Fall back on default
1090 if (!AggregatedInits.empty()) {
1091 CopyingValueRepresentation CVR(CGF);
1092 EmitMemberInitializer(CGF, ConstructorDecl->getParent(),
1093 AggregatedInits[0], ConstructorDecl, Args);
1094 AggregatedInits.clear();
1100 pushEHDestructors();
1102 AggregatedInits.clear();
1105 void pushEHDestructors() {
1106 Address ThisPtr = CGF.LoadCXXThisAddress();
1107 QualType RecordTy = CGF.getContext().getTypeDeclType(ClassDecl);
1108 LValue LHS = CGF.MakeAddrLValue(ThisPtr, RecordTy);
1110 for (unsigned i = 0; i < AggregatedInits.size(); ++i) {
1111 CXXCtorInitializer *MemberInit = AggregatedInits[i];
1112 QualType FieldType = MemberInit->getAnyMember()->getType();
1113 QualType::DestructionKind dtorKind = FieldType.isDestructedType();
1114 if (!CGF.needsEHCleanup(dtorKind))
1116 LValue FieldLHS = LHS;
1117 EmitLValueForAnyFieldInitialization(CGF, MemberInit, FieldLHS);
1118 CGF.pushEHDestroy(dtorKind, FieldLHS.getAddress(), FieldType);
1123 emitAggregatedInits();
1127 const CXXConstructorDecl *ConstructorDecl;
1128 bool MemcpyableCtor;
1129 FunctionArgList &Args;
1130 SmallVector<CXXCtorInitializer*, 16> AggregatedInits;
1133 class AssignmentMemcpyizer : public FieldMemcpyizer {
1135 // Returns the memcpyable field copied by the given statement, if one
1136 // exists. Otherwise returns null.
1137 FieldDecl *getMemcpyableField(Stmt *S) {
1138 if (!AssignmentsMemcpyable)
1140 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(S)) {
1141 // Recognise trivial assignments.
1142 if (BO->getOpcode() != BO_Assign)
1144 MemberExpr *ME = dyn_cast<MemberExpr>(BO->getLHS());
1147 FieldDecl *Field = dyn_cast<FieldDecl>(ME->getMemberDecl());
1148 if (!Field || !isMemcpyableField(Field))
1150 Stmt *RHS = BO->getRHS();
1151 if (ImplicitCastExpr *EC = dyn_cast<ImplicitCastExpr>(RHS))
1152 RHS = EC->getSubExpr();
1155 if (MemberExpr *ME2 = dyn_cast<MemberExpr>(RHS)) {
1156 if (ME2->getMemberDecl() == Field)
1160 } else if (CXXMemberCallExpr *MCE = dyn_cast<CXXMemberCallExpr>(S)) {
1161 CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MCE->getCalleeDecl());
1162 if (!(MD && isMemcpyEquivalentSpecialMember(MD)))
1164 MemberExpr *IOA = dyn_cast<MemberExpr>(MCE->getImplicitObjectArgument());
1167 FieldDecl *Field = dyn_cast<FieldDecl>(IOA->getMemberDecl());
1168 if (!Field || !isMemcpyableField(Field))
1170 MemberExpr *Arg0 = dyn_cast<MemberExpr>(MCE->getArg(0));
1171 if (!Arg0 || Field != dyn_cast<FieldDecl>(Arg0->getMemberDecl()))
1174 } else if (CallExpr *CE = dyn_cast<CallExpr>(S)) {
1175 FunctionDecl *FD = dyn_cast<FunctionDecl>(CE->getCalleeDecl());
1176 if (!FD || FD->getBuiltinID() != Builtin::BI__builtin_memcpy)
1178 Expr *DstPtr = CE->getArg(0);
1179 if (ImplicitCastExpr *DC = dyn_cast<ImplicitCastExpr>(DstPtr))
1180 DstPtr = DC->getSubExpr();
1181 UnaryOperator *DUO = dyn_cast<UnaryOperator>(DstPtr);
1182 if (!DUO || DUO->getOpcode() != UO_AddrOf)
1184 MemberExpr *ME = dyn_cast<MemberExpr>(DUO->getSubExpr());
1187 FieldDecl *Field = dyn_cast<FieldDecl>(ME->getMemberDecl());
1188 if (!Field || !isMemcpyableField(Field))
1190 Expr *SrcPtr = CE->getArg(1);
1191 if (ImplicitCastExpr *SC = dyn_cast<ImplicitCastExpr>(SrcPtr))
1192 SrcPtr = SC->getSubExpr();
1193 UnaryOperator *SUO = dyn_cast<UnaryOperator>(SrcPtr);
1194 if (!SUO || SUO->getOpcode() != UO_AddrOf)
1196 MemberExpr *ME2 = dyn_cast<MemberExpr>(SUO->getSubExpr());
1197 if (!ME2 || Field != dyn_cast<FieldDecl>(ME2->getMemberDecl()))
1205 bool AssignmentsMemcpyable;
1206 SmallVector<Stmt*, 16> AggregatedStmts;
1209 AssignmentMemcpyizer(CodeGenFunction &CGF, const CXXMethodDecl *AD,
1210 FunctionArgList &Args)
1211 : FieldMemcpyizer(CGF, AD->getParent(), Args[Args.size() - 1]),
1212 AssignmentsMemcpyable(CGF.getLangOpts().getGC() == LangOptions::NonGC) {
1213 assert(Args.size() == 2);
1216 void emitAssignment(Stmt *S) {
1217 FieldDecl *F = getMemcpyableField(S);
1219 addMemcpyableField(F);
1220 AggregatedStmts.push_back(S);
1222 emitAggregatedStmts();
1227 void emitAggregatedStmts() {
1228 if (AggregatedStmts.size() <= 1) {
1229 if (!AggregatedStmts.empty()) {
1230 CopyingValueRepresentation CVR(CGF);
1231 CGF.EmitStmt(AggregatedStmts[0]);
1237 AggregatedStmts.clear();
1241 emitAggregatedStmts();
1244 } // end anonymous namespace
1246 static bool isInitializerOfDynamicClass(const CXXCtorInitializer *BaseInit) {
1247 const Type *BaseType = BaseInit->getBaseClass();
1248 const auto *BaseClassDecl =
1249 cast<CXXRecordDecl>(BaseType->getAs<RecordType>()->getDecl());
1250 return BaseClassDecl->isDynamicClass();
1253 /// EmitCtorPrologue - This routine generates necessary code to initialize
1254 /// base classes and non-static data members belonging to this constructor.
1255 void CodeGenFunction::EmitCtorPrologue(const CXXConstructorDecl *CD,
1256 CXXCtorType CtorType,
1257 FunctionArgList &Args) {
1258 if (CD->isDelegatingConstructor())
1259 return EmitDelegatingCXXConstructorCall(CD, Args);
1261 const CXXRecordDecl *ClassDecl = CD->getParent();
1263 CXXConstructorDecl::init_const_iterator B = CD->init_begin(),
1266 llvm::BasicBlock *BaseCtorContinueBB = nullptr;
1267 if (ClassDecl->getNumVBases() &&
1268 !CGM.getTarget().getCXXABI().hasConstructorVariants()) {
1269 // The ABIs that don't have constructor variants need to put a branch
1270 // before the virtual base initialization code.
1271 BaseCtorContinueBB =
1272 CGM.getCXXABI().EmitCtorCompleteObjectHandler(*this, ClassDecl);
1273 assert(BaseCtorContinueBB);
1276 llvm::Value *const OldThis = CXXThisValue;
1277 // Virtual base initializers first.
1278 for (; B != E && (*B)->isBaseInitializer() && (*B)->isBaseVirtual(); B++) {
1279 if (CGM.getCodeGenOpts().StrictVTablePointers &&
1280 CGM.getCodeGenOpts().OptimizationLevel > 0 &&
1281 isInitializerOfDynamicClass(*B))
1282 CXXThisValue = Builder.CreateLaunderInvariantGroup(LoadCXXThis());
1283 EmitBaseInitializer(*this, ClassDecl, *B, CtorType);
1286 if (BaseCtorContinueBB) {
1287 // Complete object handler should continue to the remaining initializers.
1288 Builder.CreateBr(BaseCtorContinueBB);
1289 EmitBlock(BaseCtorContinueBB);
1292 // Then, non-virtual base initializers.
1293 for (; B != E && (*B)->isBaseInitializer(); B++) {
1294 assert(!(*B)->isBaseVirtual());
1296 if (CGM.getCodeGenOpts().StrictVTablePointers &&
1297 CGM.getCodeGenOpts().OptimizationLevel > 0 &&
1298 isInitializerOfDynamicClass(*B))
1299 CXXThisValue = Builder.CreateLaunderInvariantGroup(LoadCXXThis());
1300 EmitBaseInitializer(*this, ClassDecl, *B, CtorType);
1303 CXXThisValue = OldThis;
1305 InitializeVTablePointers(ClassDecl);
1307 // And finally, initialize class members.
1308 FieldConstructionScope FCS(*this, LoadCXXThisAddress());
1309 ConstructorMemcpyizer CM(*this, CD, Args);
1310 for (; B != E; B++) {
1311 CXXCtorInitializer *Member = (*B);
1312 assert(!Member->isBaseInitializer());
1313 assert(Member->isAnyMemberInitializer() &&
1314 "Delegating initializer on non-delegating constructor");
1315 CM.addMemberInitializer(Member);
1321 FieldHasTrivialDestructorBody(ASTContext &Context, const FieldDecl *Field);
1324 HasTrivialDestructorBody(ASTContext &Context,
1325 const CXXRecordDecl *BaseClassDecl,
1326 const CXXRecordDecl *MostDerivedClassDecl)
1328 // If the destructor is trivial we don't have to check anything else.
1329 if (BaseClassDecl->hasTrivialDestructor())
1332 if (!BaseClassDecl->getDestructor()->hasTrivialBody())
1336 for (const auto *Field : BaseClassDecl->fields())
1337 if (!FieldHasTrivialDestructorBody(Context, Field))
1340 // Check non-virtual bases.
1341 for (const auto &I : BaseClassDecl->bases()) {
1345 const CXXRecordDecl *NonVirtualBase =
1346 cast<CXXRecordDecl>(I.getType()->castAs<RecordType>()->getDecl());
1347 if (!HasTrivialDestructorBody(Context, NonVirtualBase,
1348 MostDerivedClassDecl))
1352 if (BaseClassDecl == MostDerivedClassDecl) {
1353 // Check virtual bases.
1354 for (const auto &I : BaseClassDecl->vbases()) {
1355 const CXXRecordDecl *VirtualBase =
1356 cast<CXXRecordDecl>(I.getType()->castAs<RecordType>()->getDecl());
1357 if (!HasTrivialDestructorBody(Context, VirtualBase,
1358 MostDerivedClassDecl))
1367 FieldHasTrivialDestructorBody(ASTContext &Context,
1368 const FieldDecl *Field)
1370 QualType FieldBaseElementType = Context.getBaseElementType(Field->getType());
1372 const RecordType *RT = FieldBaseElementType->getAs<RecordType>();
1376 CXXRecordDecl *FieldClassDecl = cast<CXXRecordDecl>(RT->getDecl());
1378 // The destructor for an implicit anonymous union member is never invoked.
1379 if (FieldClassDecl->isUnion() && FieldClassDecl->isAnonymousStructOrUnion())
1382 return HasTrivialDestructorBody(Context, FieldClassDecl, FieldClassDecl);
1385 /// CanSkipVTablePointerInitialization - Check whether we need to initialize
1386 /// any vtable pointers before calling this destructor.
1387 static bool CanSkipVTablePointerInitialization(CodeGenFunction &CGF,
1388 const CXXDestructorDecl *Dtor) {
1389 const CXXRecordDecl *ClassDecl = Dtor->getParent();
1390 if (!ClassDecl->isDynamicClass())
1393 if (!Dtor->hasTrivialBody())
1396 // Check the fields.
1397 for (const auto *Field : ClassDecl->fields())
1398 if (!FieldHasTrivialDestructorBody(CGF.getContext(), Field))
1404 /// EmitDestructorBody - Emits the body of the current destructor.
1405 void CodeGenFunction::EmitDestructorBody(FunctionArgList &Args) {
1406 const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CurGD.getDecl());
1407 CXXDtorType DtorType = CurGD.getDtorType();
1409 // For an abstract class, non-base destructors are never used (and can't
1410 // be emitted in general, because vbase dtors may not have been validated
1411 // by Sema), but the Itanium ABI doesn't make them optional and Clang may
1412 // in fact emit references to them from other compilations, so emit them
1413 // as functions containing a trap instruction.
1414 if (DtorType != Dtor_Base && Dtor->getParent()->isAbstract()) {
1415 llvm::CallInst *TrapCall = EmitTrapCall(llvm::Intrinsic::trap);
1416 TrapCall->setDoesNotReturn();
1417 TrapCall->setDoesNotThrow();
1418 Builder.CreateUnreachable();
1419 Builder.ClearInsertionPoint();
1423 Stmt *Body = Dtor->getBody();
1425 incrementProfileCounter(Body);
1427 // The call to operator delete in a deleting destructor happens
1428 // outside of the function-try-block, which means it's always
1429 // possible to delegate the destructor body to the complete
1430 // destructor. Do so.
1431 if (DtorType == Dtor_Deleting) {
1432 RunCleanupsScope DtorEpilogue(*this);
1433 EnterDtorCleanups(Dtor, Dtor_Deleting);
1434 if (HaveInsertPoint())
1435 EmitCXXDestructorCall(Dtor, Dtor_Complete, /*ForVirtualBase=*/false,
1436 /*Delegating=*/false, LoadCXXThisAddress());
1440 // If the body is a function-try-block, enter the try before
1442 bool isTryBody = (Body && isa<CXXTryStmt>(Body));
1444 EnterCXXTryStmt(*cast<CXXTryStmt>(Body), true);
1445 EmitAsanPrologueOrEpilogue(false);
1447 // Enter the epilogue cleanups.
1448 RunCleanupsScope DtorEpilogue(*this);
1450 // If this is the complete variant, just invoke the base variant;
1451 // the epilogue will destruct the virtual bases. But we can't do
1452 // this optimization if the body is a function-try-block, because
1453 // we'd introduce *two* handler blocks. In the Microsoft ABI, we
1454 // always delegate because we might not have a definition in this TU.
1456 case Dtor_Comdat: llvm_unreachable("not expecting a COMDAT");
1457 case Dtor_Deleting: llvm_unreachable("already handled deleting case");
1460 assert((Body || getTarget().getCXXABI().isMicrosoft()) &&
1461 "can't emit a dtor without a body for non-Microsoft ABIs");
1463 // Enter the cleanup scopes for virtual bases.
1464 EnterDtorCleanups(Dtor, Dtor_Complete);
1467 EmitCXXDestructorCall(Dtor, Dtor_Base, /*ForVirtualBase=*/false,
1468 /*Delegating=*/false, LoadCXXThisAddress());
1472 // Fallthrough: act like we're in the base variant.
1478 // Enter the cleanup scopes for fields and non-virtual bases.
1479 EnterDtorCleanups(Dtor, Dtor_Base);
1481 // Initialize the vtable pointers before entering the body.
1482 if (!CanSkipVTablePointerInitialization(*this, Dtor)) {
1483 // Insert the llvm.launder.invariant.group intrinsic before initializing
1484 // the vptrs to cancel any previous assumptions we might have made.
1485 if (CGM.getCodeGenOpts().StrictVTablePointers &&
1486 CGM.getCodeGenOpts().OptimizationLevel > 0)
1487 CXXThisValue = Builder.CreateLaunderInvariantGroup(LoadCXXThis());
1488 InitializeVTablePointers(Dtor->getParent());
1492 EmitStmt(cast<CXXTryStmt>(Body)->getTryBlock());
1496 assert(Dtor->isImplicit() && "bodyless dtor not implicit");
1497 // nothing to do besides what's in the epilogue
1499 // -fapple-kext must inline any call to this dtor into
1500 // the caller's body.
1501 if (getLangOpts().AppleKext)
1502 CurFn->addFnAttr(llvm::Attribute::AlwaysInline);
1507 // Jump out through the epilogue cleanups.
1508 DtorEpilogue.ForceCleanup();
1510 // Exit the try if applicable.
1512 ExitCXXTryStmt(*cast<CXXTryStmt>(Body), true);
1515 void CodeGenFunction::emitImplicitAssignmentOperatorBody(FunctionArgList &Args) {
1516 const CXXMethodDecl *AssignOp = cast<CXXMethodDecl>(CurGD.getDecl());
1517 const Stmt *RootS = AssignOp->getBody();
1518 assert(isa<CompoundStmt>(RootS) &&
1519 "Body of an implicit assignment operator should be compound stmt.");
1520 const CompoundStmt *RootCS = cast<CompoundStmt>(RootS);
1522 LexicalScope Scope(*this, RootCS->getSourceRange());
1524 incrementProfileCounter(RootCS);
1525 AssignmentMemcpyizer AM(*this, AssignOp, Args);
1526 for (auto *I : RootCS->body())
1527 AM.emitAssignment(I);
1532 llvm::Value *LoadThisForDtorDelete(CodeGenFunction &CGF,
1533 const CXXDestructorDecl *DD) {
1534 if (Expr *ThisArg = DD->getOperatorDeleteThisArg())
1535 return CGF.EmitScalarExpr(ThisArg);
1536 return CGF.LoadCXXThis();
1539 /// Call the operator delete associated with the current destructor.
1540 struct CallDtorDelete final : EHScopeStack::Cleanup {
1543 void Emit(CodeGenFunction &CGF, Flags flags) override {
1544 const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CGF.CurCodeDecl);
1545 const CXXRecordDecl *ClassDecl = Dtor->getParent();
1546 CGF.EmitDeleteCall(Dtor->getOperatorDelete(),
1547 LoadThisForDtorDelete(CGF, Dtor),
1548 CGF.getContext().getTagDeclType(ClassDecl));
1552 void EmitConditionalDtorDeleteCall(CodeGenFunction &CGF,
1553 llvm::Value *ShouldDeleteCondition,
1554 bool ReturnAfterDelete) {
1555 llvm::BasicBlock *callDeleteBB = CGF.createBasicBlock("dtor.call_delete");
1556 llvm::BasicBlock *continueBB = CGF.createBasicBlock("dtor.continue");
1557 llvm::Value *ShouldCallDelete
1558 = CGF.Builder.CreateIsNull(ShouldDeleteCondition);
1559 CGF.Builder.CreateCondBr(ShouldCallDelete, continueBB, callDeleteBB);
1561 CGF.EmitBlock(callDeleteBB);
1562 const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CGF.CurCodeDecl);
1563 const CXXRecordDecl *ClassDecl = Dtor->getParent();
1564 CGF.EmitDeleteCall(Dtor->getOperatorDelete(),
1565 LoadThisForDtorDelete(CGF, Dtor),
1566 CGF.getContext().getTagDeclType(ClassDecl));
1567 assert(Dtor->getOperatorDelete()->isDestroyingOperatorDelete() ==
1568 ReturnAfterDelete &&
1569 "unexpected value for ReturnAfterDelete");
1570 if (ReturnAfterDelete)
1571 CGF.EmitBranchThroughCleanup(CGF.ReturnBlock);
1573 CGF.Builder.CreateBr(continueBB);
1575 CGF.EmitBlock(continueBB);
1578 struct CallDtorDeleteConditional final : EHScopeStack::Cleanup {
1579 llvm::Value *ShouldDeleteCondition;
1582 CallDtorDeleteConditional(llvm::Value *ShouldDeleteCondition)
1583 : ShouldDeleteCondition(ShouldDeleteCondition) {
1584 assert(ShouldDeleteCondition != nullptr);
1587 void Emit(CodeGenFunction &CGF, Flags flags) override {
1588 EmitConditionalDtorDeleteCall(CGF, ShouldDeleteCondition,
1589 /*ReturnAfterDelete*/false);
1593 class DestroyField final : public EHScopeStack::Cleanup {
1594 const FieldDecl *field;
1595 CodeGenFunction::Destroyer *destroyer;
1596 bool useEHCleanupForArray;
1599 DestroyField(const FieldDecl *field, CodeGenFunction::Destroyer *destroyer,
1600 bool useEHCleanupForArray)
1601 : field(field), destroyer(destroyer),
1602 useEHCleanupForArray(useEHCleanupForArray) {}
1604 void Emit(CodeGenFunction &CGF, Flags flags) override {
1605 // Find the address of the field.
1606 Address thisValue = CGF.LoadCXXThisAddress();
1607 QualType RecordTy = CGF.getContext().getTagDeclType(field->getParent());
1608 LValue ThisLV = CGF.MakeAddrLValue(thisValue, RecordTy);
1609 LValue LV = CGF.EmitLValueForField(ThisLV, field);
1610 assert(LV.isSimple());
1612 CGF.emitDestroy(LV.getAddress(), field->getType(), destroyer,
1613 flags.isForNormalCleanup() && useEHCleanupForArray);
1617 static void EmitSanitizerDtorCallback(CodeGenFunction &CGF, llvm::Value *Ptr,
1618 CharUnits::QuantityType PoisonSize) {
1619 CodeGenFunction::SanitizerScope SanScope(&CGF);
1620 // Pass in void pointer and size of region as arguments to runtime
1622 llvm::Value *Args[] = {CGF.Builder.CreateBitCast(Ptr, CGF.VoidPtrTy),
1623 llvm::ConstantInt::get(CGF.SizeTy, PoisonSize)};
1625 llvm::Type *ArgTypes[] = {CGF.VoidPtrTy, CGF.SizeTy};
1627 llvm::FunctionType *FnType =
1628 llvm::FunctionType::get(CGF.VoidTy, ArgTypes, false);
1630 CGF.CGM.CreateRuntimeFunction(FnType, "__sanitizer_dtor_callback");
1631 CGF.EmitNounwindRuntimeCall(Fn, Args);
1634 class SanitizeDtorMembers final : public EHScopeStack::Cleanup {
1635 const CXXDestructorDecl *Dtor;
1638 SanitizeDtorMembers(const CXXDestructorDecl *Dtor) : Dtor(Dtor) {}
1640 // Generate function call for handling object poisoning.
1641 // Disables tail call elimination, to prevent the current stack frame
1642 // from disappearing from the stack trace.
1643 void Emit(CodeGenFunction &CGF, Flags flags) override {
1644 const ASTRecordLayout &Layout =
1645 CGF.getContext().getASTRecordLayout(Dtor->getParent());
1647 // Nothing to poison.
1648 if (Layout.getFieldCount() == 0)
1651 // Prevent the current stack frame from disappearing from the stack trace.
1652 CGF.CurFn->addFnAttr("disable-tail-calls", "true");
1654 // Construct pointer to region to begin poisoning, and calculate poison
1655 // size, so that only members declared in this class are poisoned.
1656 ASTContext &Context = CGF.getContext();
1657 unsigned fieldIndex = 0;
1658 int startIndex = -1;
1659 // RecordDecl::field_iterator Field;
1660 for (const FieldDecl *Field : Dtor->getParent()->fields()) {
1661 // Poison field if it is trivial
1662 if (FieldHasTrivialDestructorBody(Context, Field)) {
1663 // Start sanitizing at this field
1665 startIndex = fieldIndex;
1667 // Currently on the last field, and it must be poisoned with the
1669 if (fieldIndex == Layout.getFieldCount() - 1) {
1670 PoisonMembers(CGF, startIndex, Layout.getFieldCount());
1672 } else if (startIndex >= 0) {
1673 // No longer within a block of memory to poison, so poison the block
1674 PoisonMembers(CGF, startIndex, fieldIndex);
1675 // Re-set the start index
1683 /// \param layoutStartOffset index of the ASTRecordLayout field to
1684 /// start poisoning (inclusive)
1685 /// \param layoutEndOffset index of the ASTRecordLayout field to
1686 /// end poisoning (exclusive)
1687 void PoisonMembers(CodeGenFunction &CGF, unsigned layoutStartOffset,
1688 unsigned layoutEndOffset) {
1689 ASTContext &Context = CGF.getContext();
1690 const ASTRecordLayout &Layout =
1691 Context.getASTRecordLayout(Dtor->getParent());
1693 llvm::ConstantInt *OffsetSizePtr = llvm::ConstantInt::get(
1695 Context.toCharUnitsFromBits(Layout.getFieldOffset(layoutStartOffset))
1698 llvm::Value *OffsetPtr = CGF.Builder.CreateGEP(
1699 CGF.Builder.CreateBitCast(CGF.LoadCXXThis(), CGF.Int8PtrTy),
1702 CharUnits::QuantityType PoisonSize;
1703 if (layoutEndOffset >= Layout.getFieldCount()) {
1704 PoisonSize = Layout.getNonVirtualSize().getQuantity() -
1705 Context.toCharUnitsFromBits(
1706 Layout.getFieldOffset(layoutStartOffset))
1709 PoisonSize = Context.toCharUnitsFromBits(
1710 Layout.getFieldOffset(layoutEndOffset) -
1711 Layout.getFieldOffset(layoutStartOffset))
1715 if (PoisonSize == 0)
1718 EmitSanitizerDtorCallback(CGF, OffsetPtr, PoisonSize);
1722 class SanitizeDtorVTable final : public EHScopeStack::Cleanup {
1723 const CXXDestructorDecl *Dtor;
1726 SanitizeDtorVTable(const CXXDestructorDecl *Dtor) : Dtor(Dtor) {}
1728 // Generate function call for handling vtable pointer poisoning.
1729 void Emit(CodeGenFunction &CGF, Flags flags) override {
1730 assert(Dtor->getParent()->isDynamicClass());
1732 ASTContext &Context = CGF.getContext();
1733 // Poison vtable and vtable ptr if they exist for this class.
1734 llvm::Value *VTablePtr = CGF.LoadCXXThis();
1736 CharUnits::QuantityType PoisonSize =
1737 Context.toCharUnitsFromBits(CGF.PointerWidthInBits).getQuantity();
1738 // Pass in void pointer and size of region as arguments to runtime
1740 EmitSanitizerDtorCallback(CGF, VTablePtr, PoisonSize);
1743 } // end anonymous namespace
1745 /// Emit all code that comes at the end of class's
1746 /// destructor. This is to call destructors on members and base classes
1747 /// in reverse order of their construction.
1749 /// For a deleting destructor, this also handles the case where a destroying
1750 /// operator delete completely overrides the definition.
1751 void CodeGenFunction::EnterDtorCleanups(const CXXDestructorDecl *DD,
1752 CXXDtorType DtorType) {
1753 assert((!DD->isTrivial() || DD->hasAttr<DLLExportAttr>()) &&
1754 "Should not emit dtor epilogue for non-exported trivial dtor!");
1756 // The deleting-destructor phase just needs to call the appropriate
1757 // operator delete that Sema picked up.
1758 if (DtorType == Dtor_Deleting) {
1759 assert(DD->getOperatorDelete() &&
1760 "operator delete missing - EnterDtorCleanups");
1761 if (CXXStructorImplicitParamValue) {
1762 // If there is an implicit param to the deleting dtor, it's a boolean
1763 // telling whether this is a deleting destructor.
1764 if (DD->getOperatorDelete()->isDestroyingOperatorDelete())
1765 EmitConditionalDtorDeleteCall(*this, CXXStructorImplicitParamValue,
1766 /*ReturnAfterDelete*/true);
1768 EHStack.pushCleanup<CallDtorDeleteConditional>(
1769 NormalAndEHCleanup, CXXStructorImplicitParamValue);
1771 if (DD->getOperatorDelete()->isDestroyingOperatorDelete()) {
1772 const CXXRecordDecl *ClassDecl = DD->getParent();
1773 EmitDeleteCall(DD->getOperatorDelete(),
1774 LoadThisForDtorDelete(*this, DD),
1775 getContext().getTagDeclType(ClassDecl));
1776 EmitBranchThroughCleanup(ReturnBlock);
1778 EHStack.pushCleanup<CallDtorDelete>(NormalAndEHCleanup);
1784 const CXXRecordDecl *ClassDecl = DD->getParent();
1786 // Unions have no bases and do not call field destructors.
1787 if (ClassDecl->isUnion())
1790 // The complete-destructor phase just destructs all the virtual bases.
1791 if (DtorType == Dtor_Complete) {
1792 // Poison the vtable pointer such that access after the base
1793 // and member destructors are invoked is invalid.
1794 if (CGM.getCodeGenOpts().SanitizeMemoryUseAfterDtor &&
1795 SanOpts.has(SanitizerKind::Memory) && ClassDecl->getNumVBases() &&
1796 ClassDecl->isPolymorphic())
1797 EHStack.pushCleanup<SanitizeDtorVTable>(NormalAndEHCleanup, DD);
1799 // We push them in the forward order so that they'll be popped in
1800 // the reverse order.
1801 for (const auto &Base : ClassDecl->vbases()) {
1802 CXXRecordDecl *BaseClassDecl
1803 = cast<CXXRecordDecl>(Base.getType()->getAs<RecordType>()->getDecl());
1805 // Ignore trivial destructors.
1806 if (BaseClassDecl->hasTrivialDestructor())
1809 EHStack.pushCleanup<CallBaseDtor>(NormalAndEHCleanup,
1811 /*BaseIsVirtual*/ true);
1817 assert(DtorType == Dtor_Base);
1818 // Poison the vtable pointer if it has no virtual bases, but inherits
1819 // virtual functions.
1820 if (CGM.getCodeGenOpts().SanitizeMemoryUseAfterDtor &&
1821 SanOpts.has(SanitizerKind::Memory) && !ClassDecl->getNumVBases() &&
1822 ClassDecl->isPolymorphic())
1823 EHStack.pushCleanup<SanitizeDtorVTable>(NormalAndEHCleanup, DD);
1825 // Destroy non-virtual bases.
1826 for (const auto &Base : ClassDecl->bases()) {
1827 // Ignore virtual bases.
1828 if (Base.isVirtual())
1831 CXXRecordDecl *BaseClassDecl = Base.getType()->getAsCXXRecordDecl();
1833 // Ignore trivial destructors.
1834 if (BaseClassDecl->hasTrivialDestructor())
1837 EHStack.pushCleanup<CallBaseDtor>(NormalAndEHCleanup,
1839 /*BaseIsVirtual*/ false);
1842 // Poison fields such that access after their destructors are
1843 // invoked, and before the base class destructor runs, is invalid.
1844 if (CGM.getCodeGenOpts().SanitizeMemoryUseAfterDtor &&
1845 SanOpts.has(SanitizerKind::Memory))
1846 EHStack.pushCleanup<SanitizeDtorMembers>(NormalAndEHCleanup, DD);
1848 // Destroy direct fields.
1849 for (const auto *Field : ClassDecl->fields()) {
1850 QualType type = Field->getType();
1851 QualType::DestructionKind dtorKind = type.isDestructedType();
1852 if (!dtorKind) continue;
1854 // Anonymous union members do not have their destructors called.
1855 const RecordType *RT = type->getAsUnionType();
1856 if (RT && RT->getDecl()->isAnonymousStructOrUnion()) continue;
1858 CleanupKind cleanupKind = getCleanupKind(dtorKind);
1859 EHStack.pushCleanup<DestroyField>(cleanupKind, Field,
1860 getDestroyer(dtorKind),
1861 cleanupKind & EHCleanup);
1865 /// EmitCXXAggrConstructorCall - Emit a loop to call a particular
1866 /// constructor for each of several members of an array.
1868 /// \param ctor the constructor to call for each element
1869 /// \param arrayType the type of the array to initialize
1870 /// \param arrayBegin an arrayType*
1871 /// \param zeroInitialize true if each element should be
1872 /// zero-initialized before it is constructed
1873 void CodeGenFunction::EmitCXXAggrConstructorCall(
1874 const CXXConstructorDecl *ctor, const ArrayType *arrayType,
1875 Address arrayBegin, const CXXConstructExpr *E, bool NewPointerIsChecked,
1876 bool zeroInitialize) {
1877 QualType elementType;
1878 llvm::Value *numElements =
1879 emitArrayLength(arrayType, elementType, arrayBegin);
1881 EmitCXXAggrConstructorCall(ctor, numElements, arrayBegin, E,
1882 NewPointerIsChecked, zeroInitialize);
1885 /// EmitCXXAggrConstructorCall - Emit a loop to call a particular
1886 /// constructor for each of several members of an array.
1888 /// \param ctor the constructor to call for each element
1889 /// \param numElements the number of elements in the array;
1891 /// \param arrayBase a T*, where T is the type constructed by ctor
1892 /// \param zeroInitialize true if each element should be
1893 /// zero-initialized before it is constructed
1894 void CodeGenFunction::EmitCXXAggrConstructorCall(const CXXConstructorDecl *ctor,
1895 llvm::Value *numElements,
1897 const CXXConstructExpr *E,
1898 bool NewPointerIsChecked,
1899 bool zeroInitialize) {
1900 // It's legal for numElements to be zero. This can happen both
1901 // dynamically, because x can be zero in 'new A[x]', and statically,
1902 // because of GCC extensions that permit zero-length arrays. There
1903 // are probably legitimate places where we could assume that this
1904 // doesn't happen, but it's not clear that it's worth it.
1905 llvm::BranchInst *zeroCheckBranch = nullptr;
1907 // Optimize for a constant count.
1908 llvm::ConstantInt *constantCount
1909 = dyn_cast<llvm::ConstantInt>(numElements);
1910 if (constantCount) {
1911 // Just skip out if the constant count is zero.
1912 if (constantCount->isZero()) return;
1914 // Otherwise, emit the check.
1916 llvm::BasicBlock *loopBB = createBasicBlock("new.ctorloop");
1917 llvm::Value *iszero = Builder.CreateIsNull(numElements, "isempty");
1918 zeroCheckBranch = Builder.CreateCondBr(iszero, loopBB, loopBB);
1922 // Find the end of the array.
1923 llvm::Value *arrayBegin = arrayBase.getPointer();
1924 llvm::Value *arrayEnd = Builder.CreateInBoundsGEP(arrayBegin, numElements,
1927 // Enter the loop, setting up a phi for the current location to initialize.
1928 llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
1929 llvm::BasicBlock *loopBB = createBasicBlock("arrayctor.loop");
1931 llvm::PHINode *cur = Builder.CreatePHI(arrayBegin->getType(), 2,
1933 cur->addIncoming(arrayBegin, entryBB);
1935 // Inside the loop body, emit the constructor call on the array element.
1937 // The alignment of the base, adjusted by the size of a single element,
1938 // provides a conservative estimate of the alignment of every element.
1939 // (This assumes we never start tracking offsetted alignments.)
1941 // Note that these are complete objects and so we don't need to
1942 // use the non-virtual size or alignment.
1943 QualType type = getContext().getTypeDeclType(ctor->getParent());
1944 CharUnits eltAlignment =
1945 arrayBase.getAlignment()
1946 .alignmentOfArrayElement(getContext().getTypeSizeInChars(type));
1947 Address curAddr = Address(cur, eltAlignment);
1949 // Zero initialize the storage, if requested.
1951 EmitNullInitialization(curAddr, type);
1953 // C++ [class.temporary]p4:
1954 // There are two contexts in which temporaries are destroyed at a different
1955 // point than the end of the full-expression. The first context is when a
1956 // default constructor is called to initialize an element of an array.
1957 // If the constructor has one or more default arguments, the destruction of
1958 // every temporary created in a default argument expression is sequenced
1959 // before the construction of the next array element, if any.
1962 RunCleanupsScope Scope(*this);
1964 // Evaluate the constructor and its arguments in a regular
1965 // partial-destroy cleanup.
1966 if (getLangOpts().Exceptions &&
1967 !ctor->getParent()->hasTrivialDestructor()) {
1968 Destroyer *destroyer = destroyCXXObject;
1969 pushRegularPartialArrayCleanup(arrayBegin, cur, type, eltAlignment,
1973 EmitCXXConstructorCall(ctor, Ctor_Complete, /*ForVirtualBase=*/false,
1974 /*Delegating=*/false, curAddr, E,
1975 AggValueSlot::DoesNotOverlap, NewPointerIsChecked);
1978 // Go to the next element.
1980 Builder.CreateInBoundsGEP(cur, llvm::ConstantInt::get(SizeTy, 1),
1982 cur->addIncoming(next, Builder.GetInsertBlock());
1984 // Check whether that's the end of the loop.
1985 llvm::Value *done = Builder.CreateICmpEQ(next, arrayEnd, "arrayctor.done");
1986 llvm::BasicBlock *contBB = createBasicBlock("arrayctor.cont");
1987 Builder.CreateCondBr(done, contBB, loopBB);
1989 // Patch the earlier check to skip over the loop.
1990 if (zeroCheckBranch) zeroCheckBranch->setSuccessor(0, contBB);
1995 void CodeGenFunction::destroyCXXObject(CodeGenFunction &CGF,
1998 const RecordType *rtype = type->castAs<RecordType>();
1999 const CXXRecordDecl *record = cast<CXXRecordDecl>(rtype->getDecl());
2000 const CXXDestructorDecl *dtor = record->getDestructor();
2001 assert(!dtor->isTrivial());
2002 CGF.EmitCXXDestructorCall(dtor, Dtor_Complete, /*for vbase*/ false,
2003 /*Delegating=*/false, addr);
2006 void CodeGenFunction::EmitCXXConstructorCall(const CXXConstructorDecl *D,
2008 bool ForVirtualBase,
2009 bool Delegating, Address This,
2010 const CXXConstructExpr *E,
2011 AggValueSlot::Overlap_t Overlap,
2012 bool NewPointerIsChecked) {
2015 // Push the this ptr.
2016 Args.add(RValue::get(This.getPointer()), D->getThisType(getContext()));
2018 // If this is a trivial constructor, emit a memcpy now before we lose
2019 // the alignment information on the argument.
2020 // FIXME: It would be better to preserve alignment information into CallArg.
2021 if (isMemcpyEquivalentSpecialMember(D)) {
2022 assert(E->getNumArgs() == 1 && "unexpected argcount for trivial ctor");
2024 const Expr *Arg = E->getArg(0);
2025 LValue Src = EmitLValue(Arg);
2026 QualType DestTy = getContext().getTypeDeclType(D->getParent());
2027 LValue Dest = MakeAddrLValue(This, DestTy);
2028 EmitAggregateCopyCtor(Dest, Src, Overlap);
2032 // Add the rest of the user-supplied arguments.
2033 const FunctionProtoType *FPT = D->getType()->castAs<FunctionProtoType>();
2034 EvaluationOrder Order = E->isListInitialization()
2035 ? EvaluationOrder::ForceLeftToRight
2036 : EvaluationOrder::Default;
2037 EmitCallArgs(Args, FPT, E->arguments(), E->getConstructor(),
2038 /*ParamsToSkip*/ 0, Order);
2040 EmitCXXConstructorCall(D, Type, ForVirtualBase, Delegating, This, Args,
2041 Overlap, E->getExprLoc(), NewPointerIsChecked);
2044 static bool canEmitDelegateCallArgs(CodeGenFunction &CGF,
2045 const CXXConstructorDecl *Ctor,
2046 CXXCtorType Type, CallArgList &Args) {
2047 // We can't forward a variadic call.
2048 if (Ctor->isVariadic())
2051 if (CGF.getTarget().getCXXABI().areArgsDestroyedLeftToRightInCallee()) {
2052 // If the parameters are callee-cleanup, it's not safe to forward.
2053 for (auto *P : Ctor->parameters())
2054 if (P->getType().isDestructedType())
2057 // Likewise if they're inalloca.
2058 const CGFunctionInfo &Info =
2059 CGF.CGM.getTypes().arrangeCXXConstructorCall(Args, Ctor, Type, 0, 0);
2060 if (Info.usesInAlloca())
2064 // Anything else should be OK.
2068 void CodeGenFunction::EmitCXXConstructorCall(const CXXConstructorDecl *D,
2070 bool ForVirtualBase,
2074 AggValueSlot::Overlap_t Overlap,
2076 bool NewPointerIsChecked) {
2077 const CXXRecordDecl *ClassDecl = D->getParent();
2079 if (!NewPointerIsChecked)
2080 EmitTypeCheck(CodeGenFunction::TCK_ConstructorCall, Loc, This.getPointer(),
2081 getContext().getRecordType(ClassDecl), CharUnits::Zero());
2083 if (D->isTrivial() && D->isDefaultConstructor()) {
2084 assert(Args.size() == 1 && "trivial default ctor with args");
2088 // If this is a trivial constructor, just emit what's needed. If this is a
2089 // union copy constructor, we must emit a memcpy, because the AST does not
2091 if (isMemcpyEquivalentSpecialMember(D)) {
2092 assert(Args.size() == 2 && "unexpected argcount for trivial ctor");
2094 QualType SrcTy = D->getParamDecl(0)->getType().getNonReferenceType();
2095 Address Src(Args[1].getRValue(*this).getScalarVal(),
2096 getNaturalTypeAlignment(SrcTy));
2097 LValue SrcLVal = MakeAddrLValue(Src, SrcTy);
2098 QualType DestTy = getContext().getTypeDeclType(ClassDecl);
2099 LValue DestLVal = MakeAddrLValue(This, DestTy);
2100 EmitAggregateCopyCtor(DestLVal, SrcLVal, Overlap);
2104 bool PassPrototypeArgs = true;
2105 // Check whether we can actually emit the constructor before trying to do so.
2106 if (auto Inherited = D->getInheritedConstructor()) {
2107 PassPrototypeArgs = getTypes().inheritingCtorHasParams(Inherited, Type);
2108 if (PassPrototypeArgs && !canEmitDelegateCallArgs(*this, D, Type, Args)) {
2109 EmitInlinedInheritingCXXConstructorCall(D, Type, ForVirtualBase,
2115 // Insert any ABI-specific implicit constructor arguments.
2116 CGCXXABI::AddedStructorArgs ExtraArgs =
2117 CGM.getCXXABI().addImplicitConstructorArgs(*this, D, Type, ForVirtualBase,
2121 llvm::Constant *CalleePtr =
2122 CGM.getAddrOfCXXStructor(D, getFromCtorType(Type));
2123 const CGFunctionInfo &Info = CGM.getTypes().arrangeCXXConstructorCall(
2124 Args, D, Type, ExtraArgs.Prefix, ExtraArgs.Suffix, PassPrototypeArgs);
2125 CGCallee Callee = CGCallee::forDirect(CalleePtr, D);
2126 EmitCall(Info, Callee, ReturnValueSlot(), Args);
2128 // Generate vtable assumptions if we're constructing a complete object
2129 // with a vtable. We don't do this for base subobjects for two reasons:
2130 // first, it's incorrect for classes with virtual bases, and second, we're
2131 // about to overwrite the vptrs anyway.
2132 // We also have to make sure if we can refer to vtable:
2133 // - Otherwise we can refer to vtable if it's safe to speculatively emit.
2134 // FIXME: If vtable is used by ctor/dtor, or if vtable is external and we are
2135 // sure that definition of vtable is not hidden,
2136 // then we are always safe to refer to it.
2137 // FIXME: It looks like InstCombine is very inefficient on dealing with
2138 // assumes. Make assumption loads require -fstrict-vtable-pointers temporarily.
2139 if (CGM.getCodeGenOpts().OptimizationLevel > 0 &&
2140 ClassDecl->isDynamicClass() && Type != Ctor_Base &&
2141 CGM.getCXXABI().canSpeculativelyEmitVTable(ClassDecl) &&
2142 CGM.getCodeGenOpts().StrictVTablePointers)
2143 EmitVTableAssumptionLoads(ClassDecl, This);
2146 void CodeGenFunction::EmitInheritedCXXConstructorCall(
2147 const CXXConstructorDecl *D, bool ForVirtualBase, Address This,
2148 bool InheritedFromVBase, const CXXInheritedCtorInitExpr *E) {
2150 CallArg ThisArg(RValue::get(This.getPointer()), D->getThisType(getContext()));
2152 // Forward the parameters.
2153 if (InheritedFromVBase &&
2154 CGM.getTarget().getCXXABI().hasConstructorVariants()) {
2155 // Nothing to do; this construction is not responsible for constructing
2156 // the base class containing the inherited constructor.
2157 // FIXME: Can we just pass undef's for the remaining arguments if we don't
2158 // have constructor variants?
2159 Args.push_back(ThisArg);
2160 } else if (!CXXInheritedCtorInitExprArgs.empty()) {
2161 // The inheriting constructor was inlined; just inject its arguments.
2162 assert(CXXInheritedCtorInitExprArgs.size() >= D->getNumParams() &&
2163 "wrong number of parameters for inherited constructor call");
2164 Args = CXXInheritedCtorInitExprArgs;
2167 // The inheriting constructor was not inlined. Emit delegating arguments.
2168 Args.push_back(ThisArg);
2169 const auto *OuterCtor = cast<CXXConstructorDecl>(CurCodeDecl);
2170 assert(OuterCtor->getNumParams() == D->getNumParams());
2171 assert(!OuterCtor->isVariadic() && "should have been inlined");
2173 for (const auto *Param : OuterCtor->parameters()) {
2174 assert(getContext().hasSameUnqualifiedType(
2175 OuterCtor->getParamDecl(Param->getFunctionScopeIndex())->getType(),
2177 EmitDelegateCallArg(Args, Param, E->getLocation());
2179 // Forward __attribute__(pass_object_size).
2180 if (Param->hasAttr<PassObjectSizeAttr>()) {
2181 auto *POSParam = SizeArguments[Param];
2182 assert(POSParam && "missing pass_object_size value for forwarding");
2183 EmitDelegateCallArg(Args, POSParam, E->getLocation());
2188 EmitCXXConstructorCall(D, Ctor_Base, ForVirtualBase, /*Delegating*/false,
2189 This, Args, AggValueSlot::MayOverlap,
2190 E->getLocation(), /*NewPointerIsChecked*/true);
2193 void CodeGenFunction::EmitInlinedInheritingCXXConstructorCall(
2194 const CXXConstructorDecl *Ctor, CXXCtorType CtorType, bool ForVirtualBase,
2195 bool Delegating, CallArgList &Args) {
2196 GlobalDecl GD(Ctor, CtorType);
2197 InlinedInheritingConstructorScope Scope(*this, GD);
2198 ApplyInlineDebugLocation DebugScope(*this, GD);
2200 // Save the arguments to be passed to the inherited constructor.
2201 CXXInheritedCtorInitExprArgs = Args;
2203 FunctionArgList Params;
2204 QualType RetType = BuildFunctionArgList(CurGD, Params);
2207 // Insert any ABI-specific implicit constructor arguments.
2208 CGM.getCXXABI().addImplicitConstructorArgs(*this, Ctor, CtorType,
2209 ForVirtualBase, Delegating, Args);
2211 // Emit a simplified prolog. We only need to emit the implicit params.
2212 assert(Args.size() >= Params.size() && "too few arguments for call");
2213 for (unsigned I = 0, N = Args.size(); I != N; ++I) {
2214 if (I < Params.size() && isa<ImplicitParamDecl>(Params[I])) {
2215 const RValue &RV = Args[I].getRValue(*this);
2216 assert(!RV.isComplex() && "complex indirect params not supported");
2217 ParamValue Val = RV.isScalar()
2218 ? ParamValue::forDirect(RV.getScalarVal())
2219 : ParamValue::forIndirect(RV.getAggregateAddress());
2220 EmitParmDecl(*Params[I], Val, I + 1);
2224 // Create a return value slot if the ABI implementation wants one.
2225 // FIXME: This is dumb, we should ask the ABI not to try to set the return
2227 if (!RetType->isVoidType())
2228 ReturnValue = CreateIRTemp(RetType, "retval.inhctor");
2230 CGM.getCXXABI().EmitInstanceFunctionProlog(*this);
2231 CXXThisValue = CXXABIThisValue;
2233 // Directly emit the constructor initializers.
2234 EmitCtorPrologue(Ctor, CtorType, Params);
2237 void CodeGenFunction::EmitVTableAssumptionLoad(const VPtr &Vptr, Address This) {
2238 llvm::Value *VTableGlobal =
2239 CGM.getCXXABI().getVTableAddressPoint(Vptr.Base, Vptr.VTableClass);
2243 // We can just use the base offset in the complete class.
2244 CharUnits NonVirtualOffset = Vptr.Base.getBaseOffset();
2246 if (!NonVirtualOffset.isZero())
2248 ApplyNonVirtualAndVirtualOffset(*this, This, NonVirtualOffset, nullptr,
2249 Vptr.VTableClass, Vptr.NearestVBase);
2251 llvm::Value *VPtrValue =
2252 GetVTablePtr(This, VTableGlobal->getType(), Vptr.VTableClass);
2254 Builder.CreateICmpEQ(VPtrValue, VTableGlobal, "cmp.vtables");
2255 Builder.CreateAssumption(Cmp);
2258 void CodeGenFunction::EmitVTableAssumptionLoads(const CXXRecordDecl *ClassDecl,
2260 if (CGM.getCXXABI().doStructorsInitializeVPtrs(ClassDecl))
2261 for (const VPtr &Vptr : getVTablePointers(ClassDecl))
2262 EmitVTableAssumptionLoad(Vptr, This);
2266 CodeGenFunction::EmitSynthesizedCXXCopyCtorCall(const CXXConstructorDecl *D,
2267 Address This, Address Src,
2268 const CXXConstructExpr *E) {
2269 const FunctionProtoType *FPT = D->getType()->castAs<FunctionProtoType>();
2273 // Push the this ptr.
2274 Args.add(RValue::get(This.getPointer()), D->getThisType(getContext()));
2276 // Push the src ptr.
2277 QualType QT = *(FPT->param_type_begin());
2278 llvm::Type *t = CGM.getTypes().ConvertType(QT);
2279 Src = Builder.CreateBitCast(Src, t);
2280 Args.add(RValue::get(Src.getPointer()), QT);
2282 // Skip over first argument (Src).
2283 EmitCallArgs(Args, FPT, drop_begin(E->arguments(), 1), E->getConstructor(),
2284 /*ParamsToSkip*/ 1);
2286 EmitCXXConstructorCall(D, Ctor_Complete, /*ForVirtualBase*/false,
2287 /*Delegating*/false, This, Args,
2288 AggValueSlot::MayOverlap, E->getExprLoc(),
2289 /*NewPointerIsChecked*/false);
2293 CodeGenFunction::EmitDelegateCXXConstructorCall(const CXXConstructorDecl *Ctor,
2294 CXXCtorType CtorType,
2295 const FunctionArgList &Args,
2296 SourceLocation Loc) {
2297 CallArgList DelegateArgs;
2299 FunctionArgList::const_iterator I = Args.begin(), E = Args.end();
2300 assert(I != E && "no parameters to constructor");
2303 Address This = LoadCXXThisAddress();
2304 DelegateArgs.add(RValue::get(This.getPointer()), (*I)->getType());
2307 // FIXME: The location of the VTT parameter in the parameter list is
2308 // specific to the Itanium ABI and shouldn't be hardcoded here.
2309 if (CGM.getCXXABI().NeedsVTTParameter(CurGD)) {
2310 assert(I != E && "cannot skip vtt parameter, already done with args");
2311 assert((*I)->getType()->isPointerType() &&
2312 "skipping parameter not of vtt type");
2316 // Explicit arguments.
2317 for (; I != E; ++I) {
2318 const VarDecl *param = *I;
2319 // FIXME: per-argument source location
2320 EmitDelegateCallArg(DelegateArgs, param, Loc);
2323 EmitCXXConstructorCall(Ctor, CtorType, /*ForVirtualBase=*/false,
2324 /*Delegating=*/true, This, DelegateArgs,
2325 AggValueSlot::MayOverlap, Loc,
2326 /*NewPointerIsChecked=*/true);
2330 struct CallDelegatingCtorDtor final : EHScopeStack::Cleanup {
2331 const CXXDestructorDecl *Dtor;
2335 CallDelegatingCtorDtor(const CXXDestructorDecl *D, Address Addr,
2337 : Dtor(D), Addr(Addr), Type(Type) {}
2339 void Emit(CodeGenFunction &CGF, Flags flags) override {
2340 CGF.EmitCXXDestructorCall(Dtor, Type, /*ForVirtualBase=*/false,
2341 /*Delegating=*/true, Addr);
2344 } // end anonymous namespace
2347 CodeGenFunction::EmitDelegatingCXXConstructorCall(const CXXConstructorDecl *Ctor,
2348 const FunctionArgList &Args) {
2349 assert(Ctor->isDelegatingConstructor());
2351 Address ThisPtr = LoadCXXThisAddress();
2353 AggValueSlot AggSlot =
2354 AggValueSlot::forAddr(ThisPtr, Qualifiers(),
2355 AggValueSlot::IsDestructed,
2356 AggValueSlot::DoesNotNeedGCBarriers,
2357 AggValueSlot::IsNotAliased,
2358 AggValueSlot::MayOverlap,
2359 AggValueSlot::IsNotZeroed,
2360 // Checks are made by the code that calls constructor.
2361 AggValueSlot::IsSanitizerChecked);
2363 EmitAggExpr(Ctor->init_begin()[0]->getInit(), AggSlot);
2365 const CXXRecordDecl *ClassDecl = Ctor->getParent();
2366 if (CGM.getLangOpts().Exceptions && !ClassDecl->hasTrivialDestructor()) {
2368 CurGD.getCtorType() == Ctor_Complete ? Dtor_Complete : Dtor_Base;
2370 EHStack.pushCleanup<CallDelegatingCtorDtor>(EHCleanup,
2371 ClassDecl->getDestructor(),
2376 void CodeGenFunction::EmitCXXDestructorCall(const CXXDestructorDecl *DD,
2378 bool ForVirtualBase,
2381 CGM.getCXXABI().EmitDestructorCall(*this, DD, Type, ForVirtualBase,
2386 struct CallLocalDtor final : EHScopeStack::Cleanup {
2387 const CXXDestructorDecl *Dtor;
2390 CallLocalDtor(const CXXDestructorDecl *D, Address Addr)
2391 : Dtor(D), Addr(Addr) {}
2393 void Emit(CodeGenFunction &CGF, Flags flags) override {
2394 CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
2395 /*ForVirtualBase=*/false,
2396 /*Delegating=*/false, Addr);
2399 } // end anonymous namespace
2401 void CodeGenFunction::PushDestructorCleanup(const CXXDestructorDecl *D,
2403 EHStack.pushCleanup<CallLocalDtor>(NormalAndEHCleanup, D, Addr);
2406 void CodeGenFunction::PushDestructorCleanup(QualType T, Address Addr) {
2407 CXXRecordDecl *ClassDecl = T->getAsCXXRecordDecl();
2408 if (!ClassDecl) return;
2409 if (ClassDecl->hasTrivialDestructor()) return;
2411 const CXXDestructorDecl *D = ClassDecl->getDestructor();
2412 assert(D && D->isUsed() && "destructor not marked as used!");
2413 PushDestructorCleanup(D, Addr);
2416 void CodeGenFunction::InitializeVTablePointer(const VPtr &Vptr) {
2417 // Compute the address point.
2418 llvm::Value *VTableAddressPoint =
2419 CGM.getCXXABI().getVTableAddressPointInStructor(
2420 *this, Vptr.VTableClass, Vptr.Base, Vptr.NearestVBase);
2422 if (!VTableAddressPoint)
2425 // Compute where to store the address point.
2426 llvm::Value *VirtualOffset = nullptr;
2427 CharUnits NonVirtualOffset = CharUnits::Zero();
2429 if (CGM.getCXXABI().isVirtualOffsetNeededForVTableField(*this, Vptr)) {
2430 // We need to use the virtual base offset offset because the virtual base
2431 // might have a different offset in the most derived class.
2433 VirtualOffset = CGM.getCXXABI().GetVirtualBaseClassOffset(
2434 *this, LoadCXXThisAddress(), Vptr.VTableClass, Vptr.NearestVBase);
2435 NonVirtualOffset = Vptr.OffsetFromNearestVBase;
2437 // We can just use the base offset in the complete class.
2438 NonVirtualOffset = Vptr.Base.getBaseOffset();
2441 // Apply the offsets.
2442 Address VTableField = LoadCXXThisAddress();
2444 if (!NonVirtualOffset.isZero() || VirtualOffset)
2445 VTableField = ApplyNonVirtualAndVirtualOffset(
2446 *this, VTableField, NonVirtualOffset, VirtualOffset, Vptr.VTableClass,
2449 // Finally, store the address point. Use the same LLVM types as the field to
2450 // support optimization.
2451 llvm::Type *VTablePtrTy =
2452 llvm::FunctionType::get(CGM.Int32Ty, /*isVarArg=*/true)
2455 VTableField = Builder.CreateBitCast(VTableField, VTablePtrTy->getPointerTo());
2456 VTableAddressPoint = Builder.CreateBitCast(VTableAddressPoint, VTablePtrTy);
2458 llvm::StoreInst *Store = Builder.CreateStore(VTableAddressPoint, VTableField);
2459 TBAAAccessInfo TBAAInfo = CGM.getTBAAVTablePtrAccessInfo(VTablePtrTy);
2460 CGM.DecorateInstructionWithTBAA(Store, TBAAInfo);
2461 if (CGM.getCodeGenOpts().OptimizationLevel > 0 &&
2462 CGM.getCodeGenOpts().StrictVTablePointers)
2463 CGM.DecorateInstructionWithInvariantGroup(Store, Vptr.VTableClass);
2466 CodeGenFunction::VPtrsVector
2467 CodeGenFunction::getVTablePointers(const CXXRecordDecl *VTableClass) {
2468 CodeGenFunction::VPtrsVector VPtrsResult;
2469 VisitedVirtualBasesSetTy VBases;
2470 getVTablePointers(BaseSubobject(VTableClass, CharUnits::Zero()),
2471 /*NearestVBase=*/nullptr,
2472 /*OffsetFromNearestVBase=*/CharUnits::Zero(),
2473 /*BaseIsNonVirtualPrimaryBase=*/false, VTableClass, VBases,
2478 void CodeGenFunction::getVTablePointers(BaseSubobject Base,
2479 const CXXRecordDecl *NearestVBase,
2480 CharUnits OffsetFromNearestVBase,
2481 bool BaseIsNonVirtualPrimaryBase,
2482 const CXXRecordDecl *VTableClass,
2483 VisitedVirtualBasesSetTy &VBases,
2484 VPtrsVector &Vptrs) {
2485 // If this base is a non-virtual primary base the address point has already
2487 if (!BaseIsNonVirtualPrimaryBase) {
2488 // Initialize the vtable pointer for this base.
2489 VPtr Vptr = {Base, NearestVBase, OffsetFromNearestVBase, VTableClass};
2490 Vptrs.push_back(Vptr);
2493 const CXXRecordDecl *RD = Base.getBase();
2496 for (const auto &I : RD->bases()) {
2497 CXXRecordDecl *BaseDecl
2498 = cast<CXXRecordDecl>(I.getType()->getAs<RecordType>()->getDecl());
2500 // Ignore classes without a vtable.
2501 if (!BaseDecl->isDynamicClass())
2504 CharUnits BaseOffset;
2505 CharUnits BaseOffsetFromNearestVBase;
2506 bool BaseDeclIsNonVirtualPrimaryBase;
2508 if (I.isVirtual()) {
2509 // Check if we've visited this virtual base before.
2510 if (!VBases.insert(BaseDecl).second)
2513 const ASTRecordLayout &Layout =
2514 getContext().getASTRecordLayout(VTableClass);
2516 BaseOffset = Layout.getVBaseClassOffset(BaseDecl);
2517 BaseOffsetFromNearestVBase = CharUnits::Zero();
2518 BaseDeclIsNonVirtualPrimaryBase = false;
2520 const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
2522 BaseOffset = Base.getBaseOffset() + Layout.getBaseClassOffset(BaseDecl);
2523 BaseOffsetFromNearestVBase =
2524 OffsetFromNearestVBase + Layout.getBaseClassOffset(BaseDecl);
2525 BaseDeclIsNonVirtualPrimaryBase = Layout.getPrimaryBase() == BaseDecl;
2529 BaseSubobject(BaseDecl, BaseOffset),
2530 I.isVirtual() ? BaseDecl : NearestVBase, BaseOffsetFromNearestVBase,
2531 BaseDeclIsNonVirtualPrimaryBase, VTableClass, VBases, Vptrs);
2535 void CodeGenFunction::InitializeVTablePointers(const CXXRecordDecl *RD) {
2536 // Ignore classes without a vtable.
2537 if (!RD->isDynamicClass())
2540 // Initialize the vtable pointers for this class and all of its bases.
2541 if (CGM.getCXXABI().doStructorsInitializeVPtrs(RD))
2542 for (const VPtr &Vptr : getVTablePointers(RD))
2543 InitializeVTablePointer(Vptr);
2545 if (RD->getNumVBases())
2546 CGM.getCXXABI().initializeHiddenVirtualInheritanceMembers(*this, RD);
2549 llvm::Value *CodeGenFunction::GetVTablePtr(Address This,
2550 llvm::Type *VTableTy,
2551 const CXXRecordDecl *RD) {
2552 Address VTablePtrSrc = Builder.CreateElementBitCast(This, VTableTy);
2553 llvm::Instruction *VTable = Builder.CreateLoad(VTablePtrSrc, "vtable");
2554 TBAAAccessInfo TBAAInfo = CGM.getTBAAVTablePtrAccessInfo(VTableTy);
2555 CGM.DecorateInstructionWithTBAA(VTable, TBAAInfo);
2557 if (CGM.getCodeGenOpts().OptimizationLevel > 0 &&
2558 CGM.getCodeGenOpts().StrictVTablePointers)
2559 CGM.DecorateInstructionWithInvariantGroup(VTable, RD);
2564 // If a class has a single non-virtual base and does not introduce or override
2565 // virtual member functions or fields, it will have the same layout as its base.
2566 // This function returns the least derived such class.
2568 // Casting an instance of a base class to such a derived class is technically
2569 // undefined behavior, but it is a relatively common hack for introducing member
2570 // functions on class instances with specific properties (e.g. llvm::Operator)
2571 // that works under most compilers and should not have security implications, so
2572 // we allow it by default. It can be disabled with -fsanitize=cfi-cast-strict.
2573 static const CXXRecordDecl *
2574 LeastDerivedClassWithSameLayout(const CXXRecordDecl *RD) {
2575 if (!RD->field_empty())
2578 if (RD->getNumVBases() != 0)
2581 if (RD->getNumBases() != 1)
2584 for (const CXXMethodDecl *MD : RD->methods()) {
2585 if (MD->isVirtual()) {
2586 // Virtual member functions are only ok if they are implicit destructors
2587 // because the implicit destructor will have the same semantics as the
2588 // base class's destructor if no fields are added.
2589 if (isa<CXXDestructorDecl>(MD) && MD->isImplicit())
2595 return LeastDerivedClassWithSameLayout(
2596 RD->bases_begin()->getType()->getAsCXXRecordDecl());
2599 void CodeGenFunction::EmitTypeMetadataCodeForVCall(const CXXRecordDecl *RD,
2600 llvm::Value *VTable,
2601 SourceLocation Loc) {
2602 if (SanOpts.has(SanitizerKind::CFIVCall))
2603 EmitVTablePtrCheckForCall(RD, VTable, CodeGenFunction::CFITCK_VCall, Loc);
2604 else if (CGM.getCodeGenOpts().WholeProgramVTables &&
2605 CGM.HasHiddenLTOVisibility(RD)) {
2606 llvm::Metadata *MD =
2607 CGM.CreateMetadataIdentifierForType(QualType(RD->getTypeForDecl(), 0));
2608 llvm::Value *TypeId =
2609 llvm::MetadataAsValue::get(CGM.getLLVMContext(), MD);
2611 llvm::Value *CastedVTable = Builder.CreateBitCast(VTable, Int8PtrTy);
2612 llvm::Value *TypeTest =
2613 Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::type_test),
2614 {CastedVTable, TypeId});
2615 Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::assume), TypeTest);
2619 void CodeGenFunction::EmitVTablePtrCheckForCall(const CXXRecordDecl *RD,
2620 llvm::Value *VTable,
2621 CFITypeCheckKind TCK,
2622 SourceLocation Loc) {
2623 if (!SanOpts.has(SanitizerKind::CFICastStrict))
2624 RD = LeastDerivedClassWithSameLayout(RD);
2626 EmitVTablePtrCheck(RD, VTable, TCK, Loc);
2629 void CodeGenFunction::EmitVTablePtrCheckForCast(QualType T,
2630 llvm::Value *Derived,
2632 CFITypeCheckKind TCK,
2633 SourceLocation Loc) {
2634 if (!getLangOpts().CPlusPlus)
2637 auto *ClassTy = T->getAs<RecordType>();
2641 const CXXRecordDecl *ClassDecl = cast<CXXRecordDecl>(ClassTy->getDecl());
2643 if (!ClassDecl->isCompleteDefinition() || !ClassDecl->isDynamicClass())
2646 if (!SanOpts.has(SanitizerKind::CFICastStrict))
2647 ClassDecl = LeastDerivedClassWithSameLayout(ClassDecl);
2649 llvm::BasicBlock *ContBlock = nullptr;
2652 llvm::Value *DerivedNotNull =
2653 Builder.CreateIsNotNull(Derived, "cast.nonnull");
2655 llvm::BasicBlock *CheckBlock = createBasicBlock("cast.check");
2656 ContBlock = createBasicBlock("cast.cont");
2658 Builder.CreateCondBr(DerivedNotNull, CheckBlock, ContBlock);
2660 EmitBlock(CheckBlock);
2663 llvm::Value *VTable;
2664 std::tie(VTable, ClassDecl) = CGM.getCXXABI().LoadVTablePtr(
2665 *this, Address(Derived, getPointerAlign()), ClassDecl);
2667 EmitVTablePtrCheck(ClassDecl, VTable, TCK, Loc);
2670 Builder.CreateBr(ContBlock);
2671 EmitBlock(ContBlock);
2675 void CodeGenFunction::EmitVTablePtrCheck(const CXXRecordDecl *RD,
2676 llvm::Value *VTable,
2677 CFITypeCheckKind TCK,
2678 SourceLocation Loc) {
2679 if (!CGM.getCodeGenOpts().SanitizeCfiCrossDso &&
2680 !CGM.HasHiddenLTOVisibility(RD))
2684 llvm::SanitizerStatKind SSK;
2687 M = SanitizerKind::CFIVCall;
2688 SSK = llvm::SanStat_CFI_VCall;
2691 M = SanitizerKind::CFINVCall;
2692 SSK = llvm::SanStat_CFI_NVCall;
2694 case CFITCK_DerivedCast:
2695 M = SanitizerKind::CFIDerivedCast;
2696 SSK = llvm::SanStat_CFI_DerivedCast;
2698 case CFITCK_UnrelatedCast:
2699 M = SanitizerKind::CFIUnrelatedCast;
2700 SSK = llvm::SanStat_CFI_UnrelatedCast;
2703 case CFITCK_NVMFCall:
2704 case CFITCK_VMFCall:
2705 llvm_unreachable("unexpected sanitizer kind");
2708 std::string TypeName = RD->getQualifiedNameAsString();
2709 if (getContext().getSanitizerBlacklist().isBlacklistedType(M, TypeName))
2712 SanitizerScope SanScope(this);
2713 EmitSanitizerStatReport(SSK);
2715 llvm::Metadata *MD =
2716 CGM.CreateMetadataIdentifierForType(QualType(RD->getTypeForDecl(), 0));
2717 llvm::Value *TypeId = llvm::MetadataAsValue::get(getLLVMContext(), MD);
2719 llvm::Value *CastedVTable = Builder.CreateBitCast(VTable, Int8PtrTy);
2720 llvm::Value *TypeTest = Builder.CreateCall(
2721 CGM.getIntrinsic(llvm::Intrinsic::type_test), {CastedVTable, TypeId});
2723 llvm::Constant *StaticData[] = {
2724 llvm::ConstantInt::get(Int8Ty, TCK),
2725 EmitCheckSourceLocation(Loc),
2726 EmitCheckTypeDescriptor(QualType(RD->getTypeForDecl(), 0)),
2729 auto CrossDsoTypeId = CGM.CreateCrossDsoCfiTypeId(MD);
2730 if (CGM.getCodeGenOpts().SanitizeCfiCrossDso && CrossDsoTypeId) {
2731 EmitCfiSlowPathCheck(M, TypeTest, CrossDsoTypeId, CastedVTable, StaticData);
2735 if (CGM.getCodeGenOpts().SanitizeTrap.has(M)) {
2736 EmitTrapCheck(TypeTest);
2740 llvm::Value *AllVtables = llvm::MetadataAsValue::get(
2741 CGM.getLLVMContext(),
2742 llvm::MDString::get(CGM.getLLVMContext(), "all-vtables"));
2743 llvm::Value *ValidVtable = Builder.CreateCall(
2744 CGM.getIntrinsic(llvm::Intrinsic::type_test), {CastedVTable, AllVtables});
2745 EmitCheck(std::make_pair(TypeTest, M), SanitizerHandler::CFICheckFail,
2746 StaticData, {CastedVTable, ValidVtable});
2749 bool CodeGenFunction::ShouldEmitVTableTypeCheckedLoad(const CXXRecordDecl *RD) {
2750 if (!CGM.getCodeGenOpts().WholeProgramVTables ||
2751 !SanOpts.has(SanitizerKind::CFIVCall) ||
2752 !CGM.getCodeGenOpts().SanitizeTrap.has(SanitizerKind::CFIVCall) ||
2753 !CGM.HasHiddenLTOVisibility(RD))
2756 std::string TypeName = RD->getQualifiedNameAsString();
2757 return !getContext().getSanitizerBlacklist().isBlacklistedType(
2758 SanitizerKind::CFIVCall, TypeName);
2761 llvm::Value *CodeGenFunction::EmitVTableTypeCheckedLoad(
2762 const CXXRecordDecl *RD, llvm::Value *VTable, uint64_t VTableByteOffset) {
2763 SanitizerScope SanScope(this);
2765 EmitSanitizerStatReport(llvm::SanStat_CFI_VCall);
2767 llvm::Metadata *MD =
2768 CGM.CreateMetadataIdentifierForType(QualType(RD->getTypeForDecl(), 0));
2769 llvm::Value *TypeId = llvm::MetadataAsValue::get(CGM.getLLVMContext(), MD);
2771 llvm::Value *CastedVTable = Builder.CreateBitCast(VTable, Int8PtrTy);
2772 llvm::Value *CheckedLoad = Builder.CreateCall(
2773 CGM.getIntrinsic(llvm::Intrinsic::type_checked_load),
2774 {CastedVTable, llvm::ConstantInt::get(Int32Ty, VTableByteOffset),
2776 llvm::Value *CheckResult = Builder.CreateExtractValue(CheckedLoad, 1);
2778 EmitCheck(std::make_pair(CheckResult, SanitizerKind::CFIVCall),
2779 SanitizerHandler::CFICheckFail, nullptr, nullptr);
2781 return Builder.CreateBitCast(
2782 Builder.CreateExtractValue(CheckedLoad, 0),
2783 cast<llvm::PointerType>(VTable->getType())->getElementType());
2786 void CodeGenFunction::EmitForwardingCallToLambda(
2787 const CXXMethodDecl *callOperator,
2788 CallArgList &callArgs) {
2789 // Get the address of the call operator.
2790 const CGFunctionInfo &calleeFnInfo =
2791 CGM.getTypes().arrangeCXXMethodDeclaration(callOperator);
2792 llvm::Constant *calleePtr =
2793 CGM.GetAddrOfFunction(GlobalDecl(callOperator),
2794 CGM.getTypes().GetFunctionType(calleeFnInfo));
2796 // Prepare the return slot.
2797 const FunctionProtoType *FPT =
2798 callOperator->getType()->castAs<FunctionProtoType>();
2799 QualType resultType = FPT->getReturnType();
2800 ReturnValueSlot returnSlot;
2801 if (!resultType->isVoidType() &&
2802 calleeFnInfo.getReturnInfo().getKind() == ABIArgInfo::Indirect &&
2803 !hasScalarEvaluationKind(calleeFnInfo.getReturnType()))
2804 returnSlot = ReturnValueSlot(ReturnValue, resultType.isVolatileQualified());
2806 // We don't need to separately arrange the call arguments because
2807 // the call can't be variadic anyway --- it's impossible to forward
2808 // variadic arguments.
2810 // Now emit our call.
2811 auto callee = CGCallee::forDirect(calleePtr, callOperator);
2812 RValue RV = EmitCall(calleeFnInfo, callee, returnSlot, callArgs);
2814 // If necessary, copy the returned value into the slot.
2815 if (!resultType->isVoidType() && returnSlot.isNull()) {
2816 if (getLangOpts().ObjCAutoRefCount && resultType->isObjCRetainableType()) {
2817 RV = RValue::get(EmitARCRetainAutoreleasedReturnValue(RV.getScalarVal()));
2819 EmitReturnOfRValue(RV, resultType);
2821 EmitBranchThroughCleanup(ReturnBlock);
2824 void CodeGenFunction::EmitLambdaBlockInvokeBody() {
2825 const BlockDecl *BD = BlockInfo->getBlockDecl();
2826 const VarDecl *variable = BD->capture_begin()->getVariable();
2827 const CXXRecordDecl *Lambda = variable->getType()->getAsCXXRecordDecl();
2828 const CXXMethodDecl *CallOp = Lambda->getLambdaCallOperator();
2830 if (CallOp->isVariadic()) {
2831 // FIXME: Making this work correctly is nasty because it requires either
2832 // cloning the body of the call operator or making the call operator
2834 CGM.ErrorUnsupported(CurCodeDecl, "lambda conversion to variadic function");
2838 // Start building arguments for forwarding call
2839 CallArgList CallArgs;
2841 QualType ThisType = getContext().getPointerType(getContext().getRecordType(Lambda));
2842 Address ThisPtr = GetAddrOfBlockDecl(variable, false);
2843 CallArgs.add(RValue::get(ThisPtr.getPointer()), ThisType);
2845 // Add the rest of the parameters.
2846 for (auto param : BD->parameters())
2847 EmitDelegateCallArg(CallArgs, param, param->getLocStart());
2849 assert(!Lambda->isGenericLambda() &&
2850 "generic lambda interconversion to block not implemented");
2851 EmitForwardingCallToLambda(CallOp, CallArgs);
2854 void CodeGenFunction::EmitLambdaDelegatingInvokeBody(const CXXMethodDecl *MD) {
2855 const CXXRecordDecl *Lambda = MD->getParent();
2857 // Start building arguments for forwarding call
2858 CallArgList CallArgs;
2860 QualType ThisType = getContext().getPointerType(getContext().getRecordType(Lambda));
2861 llvm::Value *ThisPtr = llvm::UndefValue::get(getTypes().ConvertType(ThisType));
2862 CallArgs.add(RValue::get(ThisPtr), ThisType);
2864 // Add the rest of the parameters.
2865 for (auto Param : MD->parameters())
2866 EmitDelegateCallArg(CallArgs, Param, Param->getLocStart());
2868 const CXXMethodDecl *CallOp = Lambda->getLambdaCallOperator();
2869 // For a generic lambda, find the corresponding call operator specialization
2870 // to which the call to the static-invoker shall be forwarded.
2871 if (Lambda->isGenericLambda()) {
2872 assert(MD->isFunctionTemplateSpecialization());
2873 const TemplateArgumentList *TAL = MD->getTemplateSpecializationArgs();
2874 FunctionTemplateDecl *CallOpTemplate = CallOp->getDescribedFunctionTemplate();
2875 void *InsertPos = nullptr;
2876 FunctionDecl *CorrespondingCallOpSpecialization =
2877 CallOpTemplate->findSpecialization(TAL->asArray(), InsertPos);
2878 assert(CorrespondingCallOpSpecialization);
2879 CallOp = cast<CXXMethodDecl>(CorrespondingCallOpSpecialization);
2881 EmitForwardingCallToLambda(CallOp, CallArgs);
2884 void CodeGenFunction::EmitLambdaStaticInvokeBody(const CXXMethodDecl *MD) {
2885 if (MD->isVariadic()) {
2886 // FIXME: Making this work correctly is nasty because it requires either
2887 // cloning the body of the call operator or making the call operator forward.
2888 CGM.ErrorUnsupported(MD, "lambda conversion to variadic function");
2892 EmitLambdaDelegatingInvokeBody(MD);