1 //===--- CGClass.cpp - Emit LLVM Code for C++ classes -----------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This contains code dealing with C++ code generation of classes
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "CGBlocks.h"
14 #include "CGCXXABI.h"
15 #include "CGDebugInfo.h"
16 #include "CGRecordLayout.h"
17 #include "CodeGenFunction.h"
18 #include "TargetInfo.h"
19 #include "clang/AST/Attr.h"
20 #include "clang/AST/CXXInheritance.h"
21 #include "clang/AST/CharUnits.h"
22 #include "clang/AST/DeclTemplate.h"
23 #include "clang/AST/EvaluatedExprVisitor.h"
24 #include "clang/AST/RecordLayout.h"
25 #include "clang/AST/StmtCXX.h"
26 #include "clang/Basic/CodeGenOptions.h"
27 #include "clang/Basic/TargetBuiltins.h"
28 #include "clang/CodeGen/CGFunctionInfo.h"
29 #include "llvm/IR/Intrinsics.h"
30 #include "llvm/IR/Metadata.h"
31 #include "llvm/Transforms/Utils/SanitizerStats.h"
32
33 using namespace clang;
34 using namespace CodeGen;
35
36 /// Return the best known alignment for an unknown pointer to a
37 /// particular class.
getClassPointerAlignment(const CXXRecordDecl * RD)38 CharUnits CodeGenModule::getClassPointerAlignment(const CXXRecordDecl *RD) {
39 if (!RD->hasDefinition())
40 return CharUnits::One(); // Hopefully won't be used anywhere.
41
42 auto &layout = getContext().getASTRecordLayout(RD);
43
44 // If the class is final, then we know that the pointer points to an
45 // object of that type and can use the full alignment.
46 if (RD->isEffectivelyFinal())
47 return layout.getAlignment();
48
49 // Otherwise, we have to assume it could be a subclass.
50 return layout.getNonVirtualAlignment();
51 }
52
53 /// Return the smallest possible amount of storage that might be allocated
54 /// starting from the beginning of an object of a particular class.
55 ///
56 /// This may be smaller than sizeof(RD) if RD has virtual base classes.
getMinimumClassObjectSize(const CXXRecordDecl * RD)57 CharUnits CodeGenModule::getMinimumClassObjectSize(const CXXRecordDecl *RD) {
58 if (!RD->hasDefinition())
59 return CharUnits::One();
60
61 auto &layout = getContext().getASTRecordLayout(RD);
62
63 // If the class is final, then we know that the pointer points to an
64 // object of that type and can use the full alignment.
65 if (RD->isEffectivelyFinal())
66 return layout.getSize();
67
68 // Otherwise, we have to assume it could be a subclass.
69 return std::max(layout.getNonVirtualSize(), CharUnits::One());
70 }
71
72 /// Return the best known alignment for a pointer to a virtual base,
73 /// given the alignment of a pointer to the derived class.
getVBaseAlignment(CharUnits actualDerivedAlign,const CXXRecordDecl * derivedClass,const CXXRecordDecl * vbaseClass)74 CharUnits CodeGenModule::getVBaseAlignment(CharUnits actualDerivedAlign,
75 const CXXRecordDecl *derivedClass,
76 const CXXRecordDecl *vbaseClass) {
77 // The basic idea here is that an underaligned derived pointer might
78 // indicate an underaligned base pointer.
79
80 assert(vbaseClass->isCompleteDefinition());
81 auto &baseLayout = getContext().getASTRecordLayout(vbaseClass);
82 CharUnits expectedVBaseAlign = baseLayout.getNonVirtualAlignment();
83
84 return getDynamicOffsetAlignment(actualDerivedAlign, derivedClass,
85 expectedVBaseAlign);
86 }
87
88 CharUnits
getDynamicOffsetAlignment(CharUnits actualBaseAlign,const CXXRecordDecl * baseDecl,CharUnits expectedTargetAlign)89 CodeGenModule::getDynamicOffsetAlignment(CharUnits actualBaseAlign,
90 const CXXRecordDecl *baseDecl,
91 CharUnits expectedTargetAlign) {
92 // If the base is an incomplete type (which is, alas, possible with
93 // member pointers), be pessimistic.
94 if (!baseDecl->isCompleteDefinition())
95 return std::min(actualBaseAlign, expectedTargetAlign);
96
97 auto &baseLayout = getContext().getASTRecordLayout(baseDecl);
98 CharUnits expectedBaseAlign = baseLayout.getNonVirtualAlignment();
99
100 // If the class is properly aligned, assume the target offset is, too.
101 //
102 // This actually isn't necessarily the right thing to do --- if the
103 // class is a complete object, but it's only properly aligned for a
104 // base subobject, then the alignments of things relative to it are
105 // probably off as well. (Note that this requires the alignment of
106 // the target to be greater than the NV alignment of the derived
107 // class.)
108 //
109 // However, our approach to this kind of under-alignment can only
110 // ever be best effort; after all, we're never going to propagate
111 // alignments through variables or parameters. Note, in particular,
112 // that constructing a polymorphic type in an address that's less
113 // than pointer-aligned will generally trap in the constructor,
114 // unless we someday add some sort of attribute to change the
115 // assumed alignment of 'this'. So our goal here is pretty much
116 // just to allow the user to explicitly say that a pointer is
117 // under-aligned and then safely access its fields and vtables.
118 if (actualBaseAlign >= expectedBaseAlign) {
119 return expectedTargetAlign;
120 }
121
122 // Otherwise, we might be offset by an arbitrary multiple of the
123 // actual alignment. The correct adjustment is to take the min of
124 // the two alignments.
125 return std::min(actualBaseAlign, expectedTargetAlign);
126 }
127
LoadCXXThisAddress()128 Address CodeGenFunction::LoadCXXThisAddress() {
129 assert(CurFuncDecl && "loading 'this' without a func declaration?");
130 assert(isa<CXXMethodDecl>(CurFuncDecl));
131
132 // Lazily compute CXXThisAlignment.
133 if (CXXThisAlignment.isZero()) {
134 // Just use the best known alignment for the parent.
135 // TODO: if we're currently emitting a complete-object ctor/dtor,
136 // we can always use the complete-object alignment.
137 auto RD = cast<CXXMethodDecl>(CurFuncDecl)->getParent();
138 CXXThisAlignment = CGM.getClassPointerAlignment(RD);
139 }
140
141 return Address(LoadCXXThis(), CXXThisAlignment);
142 }
143
144 /// Emit the address of a field using a member data pointer.
145 ///
146 /// \param E Only used for emergency diagnostics
147 Address
EmitCXXMemberDataPointerAddress(const Expr * E,Address base,llvm::Value * memberPtr,const MemberPointerType * memberPtrType,LValueBaseInfo * BaseInfo,TBAAAccessInfo * TBAAInfo)148 CodeGenFunction::EmitCXXMemberDataPointerAddress(const Expr *E, Address base,
149 llvm::Value *memberPtr,
150 const MemberPointerType *memberPtrType,
151 LValueBaseInfo *BaseInfo,
152 TBAAAccessInfo *TBAAInfo) {
153 // Ask the ABI to compute the actual address.
154 llvm::Value *ptr =
155 CGM.getCXXABI().EmitMemberDataPointerAddress(*this, E, base,
156 memberPtr, memberPtrType);
157
158 QualType memberType = memberPtrType->getPointeeType();
159 CharUnits memberAlign =
160 CGM.getNaturalTypeAlignment(memberType, BaseInfo, TBAAInfo);
161 memberAlign =
162 CGM.getDynamicOffsetAlignment(base.getAlignment(),
163 memberPtrType->getClass()->getAsCXXRecordDecl(),
164 memberAlign);
165 return Address(ptr, memberAlign);
166 }
167
computeNonVirtualBaseClassOffset(const CXXRecordDecl * DerivedClass,CastExpr::path_const_iterator Start,CastExpr::path_const_iterator End)168 CharUnits CodeGenModule::computeNonVirtualBaseClassOffset(
169 const CXXRecordDecl *DerivedClass, CastExpr::path_const_iterator Start,
170 CastExpr::path_const_iterator End) {
171 CharUnits Offset = CharUnits::Zero();
172
173 const ASTContext &Context = getContext();
174 const CXXRecordDecl *RD = DerivedClass;
175
176 for (CastExpr::path_const_iterator I = Start; I != End; ++I) {
177 const CXXBaseSpecifier *Base = *I;
178 assert(!Base->isVirtual() && "Should not see virtual bases here!");
179
180 // Get the layout.
181 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
182
183 const auto *BaseDecl =
184 cast<CXXRecordDecl>(Base->getType()->castAs<RecordType>()->getDecl());
185
186 // Add the offset.
187 Offset += Layout.getBaseClassOffset(BaseDecl);
188
189 RD = BaseDecl;
190 }
191
192 return Offset;
193 }
194
195 llvm::Constant *
GetNonVirtualBaseClassOffset(const CXXRecordDecl * ClassDecl,CastExpr::path_const_iterator PathBegin,CastExpr::path_const_iterator PathEnd)196 CodeGenModule::GetNonVirtualBaseClassOffset(const CXXRecordDecl *ClassDecl,
197 CastExpr::path_const_iterator PathBegin,
198 CastExpr::path_const_iterator PathEnd) {
199 assert(PathBegin != PathEnd && "Base path should not be empty!");
200
201 CharUnits Offset =
202 computeNonVirtualBaseClassOffset(ClassDecl, PathBegin, PathEnd);
203 if (Offset.isZero())
204 return nullptr;
205
206 llvm::Type *PtrDiffTy =
207 Types.ConvertType(getContext().getPointerDiffType());
208
209 return llvm::ConstantInt::get(PtrDiffTy, Offset.getQuantity());
210 }
211
212 /// Gets the address of a direct base class within a complete object.
213 /// This should only be used for (1) non-virtual bases or (2) virtual bases
214 /// when the type is known to be complete (e.g. in complete destructors).
215 ///
216 /// The object pointed to by 'This' is assumed to be non-null.
217 Address
GetAddressOfDirectBaseInCompleteClass(Address This,const CXXRecordDecl * Derived,const CXXRecordDecl * Base,bool BaseIsVirtual)218 CodeGenFunction::GetAddressOfDirectBaseInCompleteClass(Address This,
219 const CXXRecordDecl *Derived,
220 const CXXRecordDecl *Base,
221 bool BaseIsVirtual) {
222 // 'this' must be a pointer (in some address space) to Derived.
223 assert(This.getElementType() == ConvertType(Derived));
224
225 // Compute the offset of the virtual base.
226 CharUnits Offset;
227 const ASTRecordLayout &Layout = getContext().getASTRecordLayout(Derived);
228 if (BaseIsVirtual)
229 Offset = Layout.getVBaseClassOffset(Base);
230 else
231 Offset = Layout.getBaseClassOffset(Base);
232
233 // Shift and cast down to the base type.
234 // TODO: for complete types, this should be possible with a GEP.
235 Address V = This;
236 if (!Offset.isZero()) {
237 V = Builder.CreateElementBitCast(V, Int8Ty);
238 V = Builder.CreateConstInBoundsByteGEP(V, Offset);
239 }
240 V = Builder.CreateElementBitCast(V, ConvertType(Base));
241
242 return V;
243 }
244
245 static Address
ApplyNonVirtualAndVirtualOffset(CodeGenFunction & CGF,Address addr,CharUnits nonVirtualOffset,llvm::Value * virtualOffset,const CXXRecordDecl * derivedClass,const CXXRecordDecl * nearestVBase)246 ApplyNonVirtualAndVirtualOffset(CodeGenFunction &CGF, Address addr,
247 CharUnits nonVirtualOffset,
248 llvm::Value *virtualOffset,
249 const CXXRecordDecl *derivedClass,
250 const CXXRecordDecl *nearestVBase) {
251 // Assert that we have something to do.
252 assert(!nonVirtualOffset.isZero() || virtualOffset != nullptr);
253
254 // Compute the offset from the static and dynamic components.
255 llvm::Value *baseOffset;
256 if (!nonVirtualOffset.isZero()) {
257 llvm::Type *OffsetType =
258 (CGF.CGM.getTarget().getCXXABI().isItaniumFamily() &&
259 CGF.CGM.getItaniumVTableContext().isRelativeLayout())
260 ? CGF.Int32Ty
261 : CGF.PtrDiffTy;
262 baseOffset =
263 llvm::ConstantInt::get(OffsetType, nonVirtualOffset.getQuantity());
264 if (virtualOffset) {
265 baseOffset = CGF.Builder.CreateAdd(virtualOffset, baseOffset);
266 }
267 } else {
268 baseOffset = virtualOffset;
269 }
270
271 // Apply the base offset.
272 llvm::Value *ptr = addr.getPointer();
273 unsigned AddrSpace = ptr->getType()->getPointerAddressSpace();
274 ptr = CGF.Builder.CreateBitCast(ptr, CGF.Int8Ty->getPointerTo(AddrSpace));
275 ptr = CGF.Builder.CreateInBoundsGEP(CGF.Int8Ty, ptr, baseOffset, "add.ptr");
276
277 // If we have a virtual component, the alignment of the result will
278 // be relative only to the known alignment of that vbase.
279 CharUnits alignment;
280 if (virtualOffset) {
281 assert(nearestVBase && "virtual offset without vbase?");
282 alignment = CGF.CGM.getVBaseAlignment(addr.getAlignment(),
283 derivedClass, nearestVBase);
284 } else {
285 alignment = addr.getAlignment();
286 }
287 alignment = alignment.alignmentAtOffset(nonVirtualOffset);
288
289 return Address(ptr, alignment);
290 }
291
GetAddressOfBaseClass(Address Value,const CXXRecordDecl * Derived,CastExpr::path_const_iterator PathBegin,CastExpr::path_const_iterator PathEnd,bool NullCheckValue,SourceLocation Loc)292 Address CodeGenFunction::GetAddressOfBaseClass(
293 Address Value, const CXXRecordDecl *Derived,
294 CastExpr::path_const_iterator PathBegin,
295 CastExpr::path_const_iterator PathEnd, bool NullCheckValue,
296 SourceLocation Loc) {
297 assert(PathBegin != PathEnd && "Base path should not be empty!");
298
299 CastExpr::path_const_iterator Start = PathBegin;
300 const CXXRecordDecl *VBase = nullptr;
301
302 // Sema has done some convenient canonicalization here: if the
303 // access path involved any virtual steps, the conversion path will
304 // *start* with a step down to the correct virtual base subobject,
305 // and hence will not require any further steps.
306 if ((*Start)->isVirtual()) {
307 VBase = cast<CXXRecordDecl>(
308 (*Start)->getType()->castAs<RecordType>()->getDecl());
309 ++Start;
310 }
311
312 // Compute the static offset of the ultimate destination within its
313 // allocating subobject (the virtual base, if there is one, or else
314 // the "complete" object that we see).
315 CharUnits NonVirtualOffset = CGM.computeNonVirtualBaseClassOffset(
316 VBase ? VBase : Derived, Start, PathEnd);
317
318 // If there's a virtual step, we can sometimes "devirtualize" it.
319 // For now, that's limited to when the derived type is final.
320 // TODO: "devirtualize" this for accesses to known-complete objects.
321 if (VBase && Derived->hasAttr<FinalAttr>()) {
322 const ASTRecordLayout &layout = getContext().getASTRecordLayout(Derived);
323 CharUnits vBaseOffset = layout.getVBaseClassOffset(VBase);
324 NonVirtualOffset += vBaseOffset;
325 VBase = nullptr; // we no longer have a virtual step
326 }
327
328 // Get the base pointer type.
329 llvm::Type *BasePtrTy =
330 ConvertType((PathEnd[-1])->getType())
331 ->getPointerTo(Value.getType()->getPointerAddressSpace());
332
333 QualType DerivedTy = getContext().getRecordType(Derived);
334 CharUnits DerivedAlign = CGM.getClassPointerAlignment(Derived);
335
336 // If the static offset is zero and we don't have a virtual step,
337 // just do a bitcast; null checks are unnecessary.
338 if (NonVirtualOffset.isZero() && !VBase) {
339 if (sanitizePerformTypeCheck()) {
340 SanitizerSet SkippedChecks;
341 SkippedChecks.set(SanitizerKind::Null, !NullCheckValue);
342 EmitTypeCheck(TCK_Upcast, Loc, Value.getPointer(),
343 DerivedTy, DerivedAlign, SkippedChecks);
344 }
345 return Builder.CreateBitCast(Value, BasePtrTy);
346 }
347
348 llvm::BasicBlock *origBB = nullptr;
349 llvm::BasicBlock *endBB = nullptr;
350
351 // Skip over the offset (and the vtable load) if we're supposed to
352 // null-check the pointer.
353 if (NullCheckValue) {
354 origBB = Builder.GetInsertBlock();
355 llvm::BasicBlock *notNullBB = createBasicBlock("cast.notnull");
356 endBB = createBasicBlock("cast.end");
357
358 llvm::Value *isNull = Builder.CreateIsNull(Value.getPointer());
359 Builder.CreateCondBr(isNull, endBB, notNullBB);
360 EmitBlock(notNullBB);
361 }
362
363 if (sanitizePerformTypeCheck()) {
364 SanitizerSet SkippedChecks;
365 SkippedChecks.set(SanitizerKind::Null, true);
366 EmitTypeCheck(VBase ? TCK_UpcastToVirtualBase : TCK_Upcast, Loc,
367 Value.getPointer(), DerivedTy, DerivedAlign, SkippedChecks);
368 }
369
370 // Compute the virtual offset.
371 llvm::Value *VirtualOffset = nullptr;
372 if (VBase) {
373 VirtualOffset =
374 CGM.getCXXABI().GetVirtualBaseClassOffset(*this, Value, Derived, VBase);
375 }
376
377 // Apply both offsets.
378 Value = ApplyNonVirtualAndVirtualOffset(*this, Value, NonVirtualOffset,
379 VirtualOffset, Derived, VBase);
380
381 // Cast to the destination type.
382 Value = Builder.CreateBitCast(Value, BasePtrTy);
383
384 // Build a phi if we needed a null check.
385 if (NullCheckValue) {
386 llvm::BasicBlock *notNullBB = Builder.GetInsertBlock();
387 Builder.CreateBr(endBB);
388 EmitBlock(endBB);
389
390 llvm::PHINode *PHI = Builder.CreatePHI(BasePtrTy, 2, "cast.result");
391 PHI->addIncoming(Value.getPointer(), notNullBB);
392 PHI->addIncoming(llvm::Constant::getNullValue(BasePtrTy), origBB);
393 Value = Address(PHI, Value.getAlignment());
394 }
395
396 return Value;
397 }
398
399 Address
GetAddressOfDerivedClass(Address BaseAddr,const CXXRecordDecl * Derived,CastExpr::path_const_iterator PathBegin,CastExpr::path_const_iterator PathEnd,bool NullCheckValue)400 CodeGenFunction::GetAddressOfDerivedClass(Address BaseAddr,
401 const CXXRecordDecl *Derived,
402 CastExpr::path_const_iterator PathBegin,
403 CastExpr::path_const_iterator PathEnd,
404 bool NullCheckValue) {
405 assert(PathBegin != PathEnd && "Base path should not be empty!");
406
407 QualType DerivedTy =
408 getContext().getCanonicalType(getContext().getTagDeclType(Derived));
409 unsigned AddrSpace =
410 BaseAddr.getPointer()->getType()->getPointerAddressSpace();
411 llvm::Type *DerivedPtrTy = ConvertType(DerivedTy)->getPointerTo(AddrSpace);
412
413 llvm::Value *NonVirtualOffset =
414 CGM.GetNonVirtualBaseClassOffset(Derived, PathBegin, PathEnd);
415
416 if (!NonVirtualOffset) {
417 // No offset, we can just cast back.
418 return Builder.CreateBitCast(BaseAddr, DerivedPtrTy);
419 }
420
421 llvm::BasicBlock *CastNull = nullptr;
422 llvm::BasicBlock *CastNotNull = nullptr;
423 llvm::BasicBlock *CastEnd = nullptr;
424
425 if (NullCheckValue) {
426 CastNull = createBasicBlock("cast.null");
427 CastNotNull = createBasicBlock("cast.notnull");
428 CastEnd = createBasicBlock("cast.end");
429
430 llvm::Value *IsNull = Builder.CreateIsNull(BaseAddr.getPointer());
431 Builder.CreateCondBr(IsNull, CastNull, CastNotNull);
432 EmitBlock(CastNotNull);
433 }
434
435 // Apply the offset.
436 llvm::Value *Value = Builder.CreateBitCast(BaseAddr.getPointer(), Int8PtrTy);
437 Value = Builder.CreateInBoundsGEP(
438 Int8Ty, Value, Builder.CreateNeg(NonVirtualOffset), "sub.ptr");
439
440 // Just cast.
441 Value = Builder.CreateBitCast(Value, DerivedPtrTy);
442
443 // Produce a PHI if we had a null-check.
444 if (NullCheckValue) {
445 Builder.CreateBr(CastEnd);
446 EmitBlock(CastNull);
447 Builder.CreateBr(CastEnd);
448 EmitBlock(CastEnd);
449
450 llvm::PHINode *PHI = Builder.CreatePHI(Value->getType(), 2);
451 PHI->addIncoming(Value, CastNotNull);
452 PHI->addIncoming(llvm::Constant::getNullValue(Value->getType()), CastNull);
453 Value = PHI;
454 }
455
456 return Address(Value, CGM.getClassPointerAlignment(Derived));
457 }
458
GetVTTParameter(GlobalDecl GD,bool ForVirtualBase,bool Delegating)459 llvm::Value *CodeGenFunction::GetVTTParameter(GlobalDecl GD,
460 bool ForVirtualBase,
461 bool Delegating) {
462 if (!CGM.getCXXABI().NeedsVTTParameter(GD)) {
463 // This constructor/destructor does not need a VTT parameter.
464 return nullptr;
465 }
466
467 const CXXRecordDecl *RD = cast<CXXMethodDecl>(CurCodeDecl)->getParent();
468 const CXXRecordDecl *Base = cast<CXXMethodDecl>(GD.getDecl())->getParent();
469
470 uint64_t SubVTTIndex;
471
472 if (Delegating) {
473 // If this is a delegating constructor call, just load the VTT.
474 return LoadCXXVTT();
475 } else if (RD == Base) {
476 // If the record matches the base, this is the complete ctor/dtor
477 // variant calling the base variant in a class with virtual bases.
478 assert(!CGM.getCXXABI().NeedsVTTParameter(CurGD) &&
479 "doing no-op VTT offset in base dtor/ctor?");
480 assert(!ForVirtualBase && "Can't have same class as virtual base!");
481 SubVTTIndex = 0;
482 } else {
483 const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
484 CharUnits BaseOffset = ForVirtualBase ?
485 Layout.getVBaseClassOffset(Base) :
486 Layout.getBaseClassOffset(Base);
487
488 SubVTTIndex =
489 CGM.getVTables().getSubVTTIndex(RD, BaseSubobject(Base, BaseOffset));
490 assert(SubVTTIndex != 0 && "Sub-VTT index must be greater than zero!");
491 }
492
493 if (CGM.getCXXABI().NeedsVTTParameter(CurGD)) {
494 // A VTT parameter was passed to the constructor, use it.
495 llvm::Value *VTT = LoadCXXVTT();
496 return Builder.CreateConstInBoundsGEP1_64(VoidPtrTy, VTT, SubVTTIndex);
497 } else {
498 // We're the complete constructor, so get the VTT by name.
499 llvm::GlobalValue *VTT = CGM.getVTables().GetAddrOfVTT(RD);
500 return Builder.CreateConstInBoundsGEP2_64(
501 VTT->getValueType(), VTT, 0, SubVTTIndex);
502 }
503 }
504
505 namespace {
506 /// Call the destructor for a direct base class.
507 struct CallBaseDtor final : EHScopeStack::Cleanup {
508 const CXXRecordDecl *BaseClass;
509 bool BaseIsVirtual;
CallBaseDtor__anondda66ac40111::CallBaseDtor510 CallBaseDtor(const CXXRecordDecl *Base, bool BaseIsVirtual)
511 : BaseClass(Base), BaseIsVirtual(BaseIsVirtual) {}
512
Emit__anondda66ac40111::CallBaseDtor513 void Emit(CodeGenFunction &CGF, Flags flags) override {
514 const CXXRecordDecl *DerivedClass =
515 cast<CXXMethodDecl>(CGF.CurCodeDecl)->getParent();
516
517 const CXXDestructorDecl *D = BaseClass->getDestructor();
518 // We are already inside a destructor, so presumably the object being
519 // destroyed should have the expected type.
520 QualType ThisTy = D->getThisObjectType();
521 Address Addr =
522 CGF.GetAddressOfDirectBaseInCompleteClass(CGF.LoadCXXThisAddress(),
523 DerivedClass, BaseClass,
524 BaseIsVirtual);
525 CGF.EmitCXXDestructorCall(D, Dtor_Base, BaseIsVirtual,
526 /*Delegating=*/false, Addr, ThisTy);
527 }
528 };
529
530 /// A visitor which checks whether an initializer uses 'this' in a
531 /// way which requires the vtable to be properly set.
532 struct DynamicThisUseChecker : ConstEvaluatedExprVisitor<DynamicThisUseChecker> {
533 typedef ConstEvaluatedExprVisitor<DynamicThisUseChecker> super;
534
535 bool UsesThis;
536
DynamicThisUseChecker__anondda66ac40111::DynamicThisUseChecker537 DynamicThisUseChecker(const ASTContext &C) : super(C), UsesThis(false) {}
538
539 // Black-list all explicit and implicit references to 'this'.
540 //
541 // Do we need to worry about external references to 'this' derived
542 // from arbitrary code? If so, then anything which runs arbitrary
543 // external code might potentially access the vtable.
VisitCXXThisExpr__anondda66ac40111::DynamicThisUseChecker544 void VisitCXXThisExpr(const CXXThisExpr *E) { UsesThis = true; }
545 };
546 } // end anonymous namespace
547
BaseInitializerUsesThis(ASTContext & C,const Expr * Init)548 static bool BaseInitializerUsesThis(ASTContext &C, const Expr *Init) {
549 DynamicThisUseChecker Checker(C);
550 Checker.Visit(Init);
551 return Checker.UsesThis;
552 }
553
EmitBaseInitializer(CodeGenFunction & CGF,const CXXRecordDecl * ClassDecl,CXXCtorInitializer * BaseInit)554 static void EmitBaseInitializer(CodeGenFunction &CGF,
555 const CXXRecordDecl *ClassDecl,
556 CXXCtorInitializer *BaseInit) {
557 assert(BaseInit->isBaseInitializer() &&
558 "Must have base initializer!");
559
560 Address ThisPtr = CGF.LoadCXXThisAddress();
561
562 const Type *BaseType = BaseInit->getBaseClass();
563 const auto *BaseClassDecl =
564 cast<CXXRecordDecl>(BaseType->castAs<RecordType>()->getDecl());
565
566 bool isBaseVirtual = BaseInit->isBaseVirtual();
567
568 // If the initializer for the base (other than the constructor
569 // itself) accesses 'this' in any way, we need to initialize the
570 // vtables.
571 if (BaseInitializerUsesThis(CGF.getContext(), BaseInit->getInit()))
572 CGF.InitializeVTablePointers(ClassDecl);
573
574 // We can pretend to be a complete class because it only matters for
575 // virtual bases, and we only do virtual bases for complete ctors.
576 Address V =
577 CGF.GetAddressOfDirectBaseInCompleteClass(ThisPtr, ClassDecl,
578 BaseClassDecl,
579 isBaseVirtual);
580 AggValueSlot AggSlot =
581 AggValueSlot::forAddr(
582 V, Qualifiers(),
583 AggValueSlot::IsDestructed,
584 AggValueSlot::DoesNotNeedGCBarriers,
585 AggValueSlot::IsNotAliased,
586 CGF.getOverlapForBaseInit(ClassDecl, BaseClassDecl, isBaseVirtual));
587
588 CGF.EmitAggExpr(BaseInit->getInit(), AggSlot);
589
590 if (CGF.CGM.getLangOpts().Exceptions &&
591 !BaseClassDecl->hasTrivialDestructor())
592 CGF.EHStack.pushCleanup<CallBaseDtor>(EHCleanup, BaseClassDecl,
593 isBaseVirtual);
594 }
595
isMemcpyEquivalentSpecialMember(const CXXMethodDecl * D)596 static bool isMemcpyEquivalentSpecialMember(const CXXMethodDecl *D) {
597 auto *CD = dyn_cast<CXXConstructorDecl>(D);
598 if (!(CD && CD->isCopyOrMoveConstructor()) &&
599 !D->isCopyAssignmentOperator() && !D->isMoveAssignmentOperator())
600 return false;
601
602 // We can emit a memcpy for a trivial copy or move constructor/assignment.
603 if (D->isTrivial() && !D->getParent()->mayInsertExtraPadding())
604 return true;
605
606 // We *must* emit a memcpy for a defaulted union copy or move op.
607 if (D->getParent()->isUnion() && D->isDefaulted())
608 return true;
609
610 return false;
611 }
612
EmitLValueForAnyFieldInitialization(CodeGenFunction & CGF,CXXCtorInitializer * MemberInit,LValue & LHS)613 static void EmitLValueForAnyFieldInitialization(CodeGenFunction &CGF,
614 CXXCtorInitializer *MemberInit,
615 LValue &LHS) {
616 FieldDecl *Field = MemberInit->getAnyMember();
617 if (MemberInit->isIndirectMemberInitializer()) {
618 // If we are initializing an anonymous union field, drill down to the field.
619 IndirectFieldDecl *IndirectField = MemberInit->getIndirectMember();
620 for (const auto *I : IndirectField->chain())
621 LHS = CGF.EmitLValueForFieldInitialization(LHS, cast<FieldDecl>(I));
622 } else {
623 LHS = CGF.EmitLValueForFieldInitialization(LHS, Field);
624 }
625 }
626
EmitMemberInitializer(CodeGenFunction & CGF,const CXXRecordDecl * ClassDecl,CXXCtorInitializer * MemberInit,const CXXConstructorDecl * Constructor,FunctionArgList & Args)627 static void EmitMemberInitializer(CodeGenFunction &CGF,
628 const CXXRecordDecl *ClassDecl,
629 CXXCtorInitializer *MemberInit,
630 const CXXConstructorDecl *Constructor,
631 FunctionArgList &Args) {
632 ApplyDebugLocation Loc(CGF, MemberInit->getSourceLocation());
633 assert(MemberInit->isAnyMemberInitializer() &&
634 "Must have member initializer!");
635 assert(MemberInit->getInit() && "Must have initializer!");
636
637 // non-static data member initializers.
638 FieldDecl *Field = MemberInit->getAnyMember();
639 QualType FieldType = Field->getType();
640
641 llvm::Value *ThisPtr = CGF.LoadCXXThis();
642 QualType RecordTy = CGF.getContext().getTypeDeclType(ClassDecl);
643 LValue LHS;
644
645 // If a base constructor is being emitted, create an LValue that has the
646 // non-virtual alignment.
647 if (CGF.CurGD.getCtorType() == Ctor_Base)
648 LHS = CGF.MakeNaturalAlignPointeeAddrLValue(ThisPtr, RecordTy);
649 else
650 LHS = CGF.MakeNaturalAlignAddrLValue(ThisPtr, RecordTy);
651
652 EmitLValueForAnyFieldInitialization(CGF, MemberInit, LHS);
653
654 // Special case: if we are in a copy or move constructor, and we are copying
655 // an array of PODs or classes with trivial copy constructors, ignore the
656 // AST and perform the copy we know is equivalent.
657 // FIXME: This is hacky at best... if we had a bit more explicit information
658 // in the AST, we could generalize it more easily.
659 const ConstantArrayType *Array
660 = CGF.getContext().getAsConstantArrayType(FieldType);
661 if (Array && Constructor->isDefaulted() &&
662 Constructor->isCopyOrMoveConstructor()) {
663 QualType BaseElementTy = CGF.getContext().getBaseElementType(Array);
664 CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(MemberInit->getInit());
665 if (BaseElementTy.isPODType(CGF.getContext()) ||
666 (CE && isMemcpyEquivalentSpecialMember(CE->getConstructor()))) {
667 unsigned SrcArgIndex =
668 CGF.CGM.getCXXABI().getSrcArgforCopyCtor(Constructor, Args);
669 llvm::Value *SrcPtr
670 = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(Args[SrcArgIndex]));
671 LValue ThisRHSLV = CGF.MakeNaturalAlignAddrLValue(SrcPtr, RecordTy);
672 LValue Src = CGF.EmitLValueForFieldInitialization(ThisRHSLV, Field);
673
674 // Copy the aggregate.
675 CGF.EmitAggregateCopy(LHS, Src, FieldType, CGF.getOverlapForFieldInit(Field),
676 LHS.isVolatileQualified());
677 // Ensure that we destroy the objects if an exception is thrown later in
678 // the constructor.
679 QualType::DestructionKind dtorKind = FieldType.isDestructedType();
680 if (CGF.needsEHCleanup(dtorKind))
681 CGF.pushEHDestroy(dtorKind, LHS.getAddress(CGF), FieldType);
682 return;
683 }
684 }
685
686 CGF.EmitInitializerForField(Field, LHS, MemberInit->getInit());
687 }
688
EmitInitializerForField(FieldDecl * Field,LValue LHS,Expr * Init)689 void CodeGenFunction::EmitInitializerForField(FieldDecl *Field, LValue LHS,
690 Expr *Init) {
691 QualType FieldType = Field->getType();
692 switch (getEvaluationKind(FieldType)) {
693 case TEK_Scalar:
694 if (LHS.isSimple()) {
695 EmitExprAsInit(Init, Field, LHS, false);
696 } else {
697 RValue RHS = RValue::get(EmitScalarExpr(Init));
698 EmitStoreThroughLValue(RHS, LHS);
699 }
700 break;
701 case TEK_Complex:
702 EmitComplexExprIntoLValue(Init, LHS, /*isInit*/ true);
703 break;
704 case TEK_Aggregate: {
705 AggValueSlot Slot = AggValueSlot::forLValue(
706 LHS, *this, AggValueSlot::IsDestructed,
707 AggValueSlot::DoesNotNeedGCBarriers, AggValueSlot::IsNotAliased,
708 getOverlapForFieldInit(Field), AggValueSlot::IsNotZeroed,
709 // Checks are made by the code that calls constructor.
710 AggValueSlot::IsSanitizerChecked);
711 EmitAggExpr(Init, Slot);
712 break;
713 }
714 }
715
716 // Ensure that we destroy this object if an exception is thrown
717 // later in the constructor.
718 QualType::DestructionKind dtorKind = FieldType.isDestructedType();
719 if (needsEHCleanup(dtorKind))
720 pushEHDestroy(dtorKind, LHS.getAddress(*this), FieldType);
721 }
722
723 /// Checks whether the given constructor is a valid subject for the
724 /// complete-to-base constructor delegation optimization, i.e.
725 /// emitting the complete constructor as a simple call to the base
726 /// constructor.
IsConstructorDelegationValid(const CXXConstructorDecl * Ctor)727 bool CodeGenFunction::IsConstructorDelegationValid(
728 const CXXConstructorDecl *Ctor) {
729
730 // Currently we disable the optimization for classes with virtual
731 // bases because (1) the addresses of parameter variables need to be
732 // consistent across all initializers but (2) the delegate function
733 // call necessarily creates a second copy of the parameter variable.
734 //
735 // The limiting example (purely theoretical AFAIK):
736 // struct A { A(int &c) { c++; } };
737 // struct B : virtual A {
738 // B(int count) : A(count) { printf("%d\n", count); }
739 // };
740 // ...although even this example could in principle be emitted as a
741 // delegation since the address of the parameter doesn't escape.
742 if (Ctor->getParent()->getNumVBases()) {
743 // TODO: white-list trivial vbase initializers. This case wouldn't
744 // be subject to the restrictions below.
745
746 // TODO: white-list cases where:
747 // - there are no non-reference parameters to the constructor
748 // - the initializers don't access any non-reference parameters
749 // - the initializers don't take the address of non-reference
750 // parameters
751 // - etc.
752 // If we ever add any of the above cases, remember that:
753 // - function-try-blocks will always exclude this optimization
754 // - we need to perform the constructor prologue and cleanup in
755 // EmitConstructorBody.
756
757 return false;
758 }
759
760 // We also disable the optimization for variadic functions because
761 // it's impossible to "re-pass" varargs.
762 if (Ctor->getType()->castAs<FunctionProtoType>()->isVariadic())
763 return false;
764
765 // FIXME: Decide if we can do a delegation of a delegating constructor.
766 if (Ctor->isDelegatingConstructor())
767 return false;
768
769 return true;
770 }
771
772 // Emit code in ctor (Prologue==true) or dtor (Prologue==false)
773 // to poison the extra field paddings inserted under
774 // -fsanitize-address-field-padding=1|2.
EmitAsanPrologueOrEpilogue(bool Prologue)775 void CodeGenFunction::EmitAsanPrologueOrEpilogue(bool Prologue) {
776 ASTContext &Context = getContext();
777 const CXXRecordDecl *ClassDecl =
778 Prologue ? cast<CXXConstructorDecl>(CurGD.getDecl())->getParent()
779 : cast<CXXDestructorDecl>(CurGD.getDecl())->getParent();
780 if (!ClassDecl->mayInsertExtraPadding()) return;
781
782 struct SizeAndOffset {
783 uint64_t Size;
784 uint64_t Offset;
785 };
786
787 unsigned PtrSize = CGM.getDataLayout().getPointerSizeInBits();
788 const ASTRecordLayout &Info = Context.getASTRecordLayout(ClassDecl);
789
790 // Populate sizes and offsets of fields.
791 SmallVector<SizeAndOffset, 16> SSV(Info.getFieldCount());
792 for (unsigned i = 0, e = Info.getFieldCount(); i != e; ++i)
793 SSV[i].Offset =
794 Context.toCharUnitsFromBits(Info.getFieldOffset(i)).getQuantity();
795
796 size_t NumFields = 0;
797 for (const auto *Field : ClassDecl->fields()) {
798 const FieldDecl *D = Field;
799 auto FieldInfo = Context.getTypeInfoInChars(D->getType());
800 CharUnits FieldSize = FieldInfo.Width;
801 assert(NumFields < SSV.size());
802 SSV[NumFields].Size = D->isBitField() ? 0 : FieldSize.getQuantity();
803 NumFields++;
804 }
805 assert(NumFields == SSV.size());
806 if (SSV.size() <= 1) return;
807
808 // We will insert calls to __asan_* run-time functions.
809 // LLVM AddressSanitizer pass may decide to inline them later.
810 llvm::Type *Args[2] = {IntPtrTy, IntPtrTy};
811 llvm::FunctionType *FTy =
812 llvm::FunctionType::get(CGM.VoidTy, Args, false);
813 llvm::FunctionCallee F = CGM.CreateRuntimeFunction(
814 FTy, Prologue ? "__asan_poison_intra_object_redzone"
815 : "__asan_unpoison_intra_object_redzone");
816
817 llvm::Value *ThisPtr = LoadCXXThis();
818 ThisPtr = Builder.CreatePtrToInt(ThisPtr, IntPtrTy);
819 uint64_t TypeSize = Info.getNonVirtualSize().getQuantity();
820 // For each field check if it has sufficient padding,
821 // if so (un)poison it with a call.
822 for (size_t i = 0; i < SSV.size(); i++) {
823 uint64_t AsanAlignment = 8;
824 uint64_t NextField = i == SSV.size() - 1 ? TypeSize : SSV[i + 1].Offset;
825 uint64_t PoisonSize = NextField - SSV[i].Offset - SSV[i].Size;
826 uint64_t EndOffset = SSV[i].Offset + SSV[i].Size;
827 if (PoisonSize < AsanAlignment || !SSV[i].Size ||
828 (NextField % AsanAlignment) != 0)
829 continue;
830 Builder.CreateCall(
831 F, {Builder.CreateAdd(ThisPtr, Builder.getIntN(PtrSize, EndOffset)),
832 Builder.getIntN(PtrSize, PoisonSize)});
833 }
834 }
835
836 /// EmitConstructorBody - Emits the body of the current constructor.
EmitConstructorBody(FunctionArgList & Args)837 void CodeGenFunction::EmitConstructorBody(FunctionArgList &Args) {
838 EmitAsanPrologueOrEpilogue(true);
839 const CXXConstructorDecl *Ctor = cast<CXXConstructorDecl>(CurGD.getDecl());
840 CXXCtorType CtorType = CurGD.getCtorType();
841
842 assert((CGM.getTarget().getCXXABI().hasConstructorVariants() ||
843 CtorType == Ctor_Complete) &&
844 "can only generate complete ctor for this ABI");
845
846 // Before we go any further, try the complete->base constructor
847 // delegation optimization.
848 if (CtorType == Ctor_Complete && IsConstructorDelegationValid(Ctor) &&
849 CGM.getTarget().getCXXABI().hasConstructorVariants()) {
850 EmitDelegateCXXConstructorCall(Ctor, Ctor_Base, Args, Ctor->getEndLoc());
851 return;
852 }
853
854 const FunctionDecl *Definition = nullptr;
855 Stmt *Body = Ctor->getBody(Definition);
856 assert(Definition == Ctor && "emitting wrong constructor body");
857
858 // Enter the function-try-block before the constructor prologue if
859 // applicable.
860 bool IsTryBody = (Body && isa<CXXTryStmt>(Body));
861 if (IsTryBody)
862 EnterCXXTryStmt(*cast<CXXTryStmt>(Body), true);
863
864 incrementProfileCounter(Body);
865
866 RunCleanupsScope RunCleanups(*this);
867
868 // TODO: in restricted cases, we can emit the vbase initializers of
869 // a complete ctor and then delegate to the base ctor.
870
871 // Emit the constructor prologue, i.e. the base and member
872 // initializers.
873 EmitCtorPrologue(Ctor, CtorType, Args);
874
875 // Emit the body of the statement.
876 if (IsTryBody)
877 EmitStmt(cast<CXXTryStmt>(Body)->getTryBlock());
878 else if (Body)
879 EmitStmt(Body);
880
881 // Emit any cleanup blocks associated with the member or base
882 // initializers, which includes (along the exceptional path) the
883 // destructors for those members and bases that were fully
884 // constructed.
885 RunCleanups.ForceCleanup();
886
887 if (IsTryBody)
888 ExitCXXTryStmt(*cast<CXXTryStmt>(Body), true);
889 }
890
891 namespace {
892 /// RAII object to indicate that codegen is copying the value representation
893 /// instead of the object representation. Useful when copying a struct or
894 /// class which has uninitialized members and we're only performing
895 /// lvalue-to-rvalue conversion on the object but not its members.
896 class CopyingValueRepresentation {
897 public:
CopyingValueRepresentation(CodeGenFunction & CGF)898 explicit CopyingValueRepresentation(CodeGenFunction &CGF)
899 : CGF(CGF), OldSanOpts(CGF.SanOpts) {
900 CGF.SanOpts.set(SanitizerKind::Bool, false);
901 CGF.SanOpts.set(SanitizerKind::Enum, false);
902 }
~CopyingValueRepresentation()903 ~CopyingValueRepresentation() {
904 CGF.SanOpts = OldSanOpts;
905 }
906 private:
907 CodeGenFunction &CGF;
908 SanitizerSet OldSanOpts;
909 };
910 } // end anonymous namespace
911
912 namespace {
913 class FieldMemcpyizer {
914 public:
FieldMemcpyizer(CodeGenFunction & CGF,const CXXRecordDecl * ClassDecl,const VarDecl * SrcRec)915 FieldMemcpyizer(CodeGenFunction &CGF, const CXXRecordDecl *ClassDecl,
916 const VarDecl *SrcRec)
917 : CGF(CGF), ClassDecl(ClassDecl), SrcRec(SrcRec),
918 RecLayout(CGF.getContext().getASTRecordLayout(ClassDecl)),
919 FirstField(nullptr), LastField(nullptr), FirstFieldOffset(0),
920 LastFieldOffset(0), LastAddedFieldIndex(0) {}
921
isMemcpyableField(FieldDecl * F) const922 bool isMemcpyableField(FieldDecl *F) const {
923 // Never memcpy fields when we are adding poisoned paddings.
924 if (CGF.getContext().getLangOpts().SanitizeAddressFieldPadding)
925 return false;
926 Qualifiers Qual = F->getType().getQualifiers();
927 if (Qual.hasVolatile() || Qual.hasObjCLifetime())
928 return false;
929 return true;
930 }
931
addMemcpyableField(FieldDecl * F)932 void addMemcpyableField(FieldDecl *F) {
933 if (F->isZeroSize(CGF.getContext()))
934 return;
935 if (!FirstField)
936 addInitialField(F);
937 else
938 addNextField(F);
939 }
940
getMemcpySize(uint64_t FirstByteOffset) const941 CharUnits getMemcpySize(uint64_t FirstByteOffset) const {
942 ASTContext &Ctx = CGF.getContext();
943 unsigned LastFieldSize =
944 LastField->isBitField()
945 ? LastField->getBitWidthValue(Ctx)
946 : Ctx.toBits(
947 Ctx.getTypeInfoDataSizeInChars(LastField->getType()).Width);
948 uint64_t MemcpySizeBits = LastFieldOffset + LastFieldSize -
949 FirstByteOffset + Ctx.getCharWidth() - 1;
950 CharUnits MemcpySize = Ctx.toCharUnitsFromBits(MemcpySizeBits);
951 return MemcpySize;
952 }
953
emitMemcpy()954 void emitMemcpy() {
955 // Give the subclass a chance to bail out if it feels the memcpy isn't
956 // worth it (e.g. Hasn't aggregated enough data).
957 if (!FirstField) {
958 return;
959 }
960
961 uint64_t FirstByteOffset;
962 if (FirstField->isBitField()) {
963 const CGRecordLayout &RL =
964 CGF.getTypes().getCGRecordLayout(FirstField->getParent());
965 const CGBitFieldInfo &BFInfo = RL.getBitFieldInfo(FirstField);
966 // FirstFieldOffset is not appropriate for bitfields,
967 // we need to use the storage offset instead.
968 FirstByteOffset = CGF.getContext().toBits(BFInfo.StorageOffset);
969 } else {
970 FirstByteOffset = FirstFieldOffset;
971 }
972
973 CharUnits MemcpySize = getMemcpySize(FirstByteOffset);
974 QualType RecordTy = CGF.getContext().getTypeDeclType(ClassDecl);
975 Address ThisPtr = CGF.LoadCXXThisAddress();
976 LValue DestLV = CGF.MakeAddrLValue(ThisPtr, RecordTy);
977 LValue Dest = CGF.EmitLValueForFieldInitialization(DestLV, FirstField);
978 llvm::Value *SrcPtr = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(SrcRec));
979 LValue SrcLV = CGF.MakeNaturalAlignAddrLValue(SrcPtr, RecordTy);
980 LValue Src = CGF.EmitLValueForFieldInitialization(SrcLV, FirstField);
981
982 emitMemcpyIR(
983 Dest.isBitField() ? Dest.getBitFieldAddress() : Dest.getAddress(CGF),
984 Src.isBitField() ? Src.getBitFieldAddress() : Src.getAddress(CGF),
985 MemcpySize);
986 reset();
987 }
988
reset()989 void reset() {
990 FirstField = nullptr;
991 }
992
993 protected:
994 CodeGenFunction &CGF;
995 const CXXRecordDecl *ClassDecl;
996
997 private:
emitMemcpyIR(Address DestPtr,Address SrcPtr,CharUnits Size)998 void emitMemcpyIR(Address DestPtr, Address SrcPtr, CharUnits Size) {
999 llvm::PointerType *DPT = DestPtr.getType();
1000 llvm::Type *DBP =
1001 llvm::Type::getInt8PtrTy(CGF.getLLVMContext(), DPT->getAddressSpace());
1002 DestPtr = CGF.Builder.CreateBitCast(DestPtr, DBP);
1003
1004 llvm::PointerType *SPT = SrcPtr.getType();
1005 llvm::Type *SBP =
1006 llvm::Type::getInt8PtrTy(CGF.getLLVMContext(), SPT->getAddressSpace());
1007 SrcPtr = CGF.Builder.CreateBitCast(SrcPtr, SBP);
1008
1009 CGF.Builder.CreateMemCpy(DestPtr, SrcPtr, Size.getQuantity());
1010 }
1011
addInitialField(FieldDecl * F)1012 void addInitialField(FieldDecl *F) {
1013 FirstField = F;
1014 LastField = F;
1015 FirstFieldOffset = RecLayout.getFieldOffset(F->getFieldIndex());
1016 LastFieldOffset = FirstFieldOffset;
1017 LastAddedFieldIndex = F->getFieldIndex();
1018 }
1019
addNextField(FieldDecl * F)1020 void addNextField(FieldDecl *F) {
1021 // For the most part, the following invariant will hold:
1022 // F->getFieldIndex() == LastAddedFieldIndex + 1
1023 // The one exception is that Sema won't add a copy-initializer for an
1024 // unnamed bitfield, which will show up here as a gap in the sequence.
1025 assert(F->getFieldIndex() >= LastAddedFieldIndex + 1 &&
1026 "Cannot aggregate fields out of order.");
1027 LastAddedFieldIndex = F->getFieldIndex();
1028
1029 // The 'first' and 'last' fields are chosen by offset, rather than field
1030 // index. This allows the code to support bitfields, as well as regular
1031 // fields.
1032 uint64_t FOffset = RecLayout.getFieldOffset(F->getFieldIndex());
1033 if (FOffset < FirstFieldOffset) {
1034 FirstField = F;
1035 FirstFieldOffset = FOffset;
1036 } else if (FOffset >= LastFieldOffset) {
1037 LastField = F;
1038 LastFieldOffset = FOffset;
1039 }
1040 }
1041
1042 const VarDecl *SrcRec;
1043 const ASTRecordLayout &RecLayout;
1044 FieldDecl *FirstField;
1045 FieldDecl *LastField;
1046 uint64_t FirstFieldOffset, LastFieldOffset;
1047 unsigned LastAddedFieldIndex;
1048 };
1049
1050 class ConstructorMemcpyizer : public FieldMemcpyizer {
1051 private:
1052 /// Get source argument for copy constructor. Returns null if not a copy
1053 /// constructor.
getTrivialCopySource(CodeGenFunction & CGF,const CXXConstructorDecl * CD,FunctionArgList & Args)1054 static const VarDecl *getTrivialCopySource(CodeGenFunction &CGF,
1055 const CXXConstructorDecl *CD,
1056 FunctionArgList &Args) {
1057 if (CD->isCopyOrMoveConstructor() && CD->isDefaulted())
1058 return Args[CGF.CGM.getCXXABI().getSrcArgforCopyCtor(CD, Args)];
1059 return nullptr;
1060 }
1061
1062 // Returns true if a CXXCtorInitializer represents a member initialization
1063 // that can be rolled into a memcpy.
isMemberInitMemcpyable(CXXCtorInitializer * MemberInit) const1064 bool isMemberInitMemcpyable(CXXCtorInitializer *MemberInit) const {
1065 if (!MemcpyableCtor)
1066 return false;
1067 FieldDecl *Field = MemberInit->getMember();
1068 assert(Field && "No field for member init.");
1069 QualType FieldType = Field->getType();
1070 CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(MemberInit->getInit());
1071
1072 // Bail out on non-memcpyable, not-trivially-copyable members.
1073 if (!(CE && isMemcpyEquivalentSpecialMember(CE->getConstructor())) &&
1074 !(FieldType.isTriviallyCopyableType(CGF.getContext()) ||
1075 FieldType->isReferenceType()))
1076 return false;
1077
1078 // Bail out on volatile fields.
1079 if (!isMemcpyableField(Field))
1080 return false;
1081
1082 // Otherwise we're good.
1083 return true;
1084 }
1085
1086 public:
ConstructorMemcpyizer(CodeGenFunction & CGF,const CXXConstructorDecl * CD,FunctionArgList & Args)1087 ConstructorMemcpyizer(CodeGenFunction &CGF, const CXXConstructorDecl *CD,
1088 FunctionArgList &Args)
1089 : FieldMemcpyizer(CGF, CD->getParent(), getTrivialCopySource(CGF, CD, Args)),
1090 ConstructorDecl(CD),
1091 MemcpyableCtor(CD->isDefaulted() &&
1092 CD->isCopyOrMoveConstructor() &&
1093 CGF.getLangOpts().getGC() == LangOptions::NonGC),
1094 Args(Args) { }
1095
addMemberInitializer(CXXCtorInitializer * MemberInit)1096 void addMemberInitializer(CXXCtorInitializer *MemberInit) {
1097 if (isMemberInitMemcpyable(MemberInit)) {
1098 AggregatedInits.push_back(MemberInit);
1099 addMemcpyableField(MemberInit->getMember());
1100 } else {
1101 emitAggregatedInits();
1102 EmitMemberInitializer(CGF, ConstructorDecl->getParent(), MemberInit,
1103 ConstructorDecl, Args);
1104 }
1105 }
1106
emitAggregatedInits()1107 void emitAggregatedInits() {
1108 if (AggregatedInits.size() <= 1) {
1109 // This memcpy is too small to be worthwhile. Fall back on default
1110 // codegen.
1111 if (!AggregatedInits.empty()) {
1112 CopyingValueRepresentation CVR(CGF);
1113 EmitMemberInitializer(CGF, ConstructorDecl->getParent(),
1114 AggregatedInits[0], ConstructorDecl, Args);
1115 AggregatedInits.clear();
1116 }
1117 reset();
1118 return;
1119 }
1120
1121 pushEHDestructors();
1122 emitMemcpy();
1123 AggregatedInits.clear();
1124 }
1125
pushEHDestructors()1126 void pushEHDestructors() {
1127 Address ThisPtr = CGF.LoadCXXThisAddress();
1128 QualType RecordTy = CGF.getContext().getTypeDeclType(ClassDecl);
1129 LValue LHS = CGF.MakeAddrLValue(ThisPtr, RecordTy);
1130
1131 for (unsigned i = 0; i < AggregatedInits.size(); ++i) {
1132 CXXCtorInitializer *MemberInit = AggregatedInits[i];
1133 QualType FieldType = MemberInit->getAnyMember()->getType();
1134 QualType::DestructionKind dtorKind = FieldType.isDestructedType();
1135 if (!CGF.needsEHCleanup(dtorKind))
1136 continue;
1137 LValue FieldLHS = LHS;
1138 EmitLValueForAnyFieldInitialization(CGF, MemberInit, FieldLHS);
1139 CGF.pushEHDestroy(dtorKind, FieldLHS.getAddress(CGF), FieldType);
1140 }
1141 }
1142
finish()1143 void finish() {
1144 emitAggregatedInits();
1145 }
1146
1147 private:
1148 const CXXConstructorDecl *ConstructorDecl;
1149 bool MemcpyableCtor;
1150 FunctionArgList &Args;
1151 SmallVector<CXXCtorInitializer*, 16> AggregatedInits;
1152 };
1153
1154 class AssignmentMemcpyizer : public FieldMemcpyizer {
1155 private:
1156 // Returns the memcpyable field copied by the given statement, if one
1157 // exists. Otherwise returns null.
getMemcpyableField(Stmt * S)1158 FieldDecl *getMemcpyableField(Stmt *S) {
1159 if (!AssignmentsMemcpyable)
1160 return nullptr;
1161 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(S)) {
1162 // Recognise trivial assignments.
1163 if (BO->getOpcode() != BO_Assign)
1164 return nullptr;
1165 MemberExpr *ME = dyn_cast<MemberExpr>(BO->getLHS());
1166 if (!ME)
1167 return nullptr;
1168 FieldDecl *Field = dyn_cast<FieldDecl>(ME->getMemberDecl());
1169 if (!Field || !isMemcpyableField(Field))
1170 return nullptr;
1171 Stmt *RHS = BO->getRHS();
1172 if (ImplicitCastExpr *EC = dyn_cast<ImplicitCastExpr>(RHS))
1173 RHS = EC->getSubExpr();
1174 if (!RHS)
1175 return nullptr;
1176 if (MemberExpr *ME2 = dyn_cast<MemberExpr>(RHS)) {
1177 if (ME2->getMemberDecl() == Field)
1178 return Field;
1179 }
1180 return nullptr;
1181 } else if (CXXMemberCallExpr *MCE = dyn_cast<CXXMemberCallExpr>(S)) {
1182 CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MCE->getCalleeDecl());
1183 if (!(MD && isMemcpyEquivalentSpecialMember(MD)))
1184 return nullptr;
1185 MemberExpr *IOA = dyn_cast<MemberExpr>(MCE->getImplicitObjectArgument());
1186 if (!IOA)
1187 return nullptr;
1188 FieldDecl *Field = dyn_cast<FieldDecl>(IOA->getMemberDecl());
1189 if (!Field || !isMemcpyableField(Field))
1190 return nullptr;
1191 MemberExpr *Arg0 = dyn_cast<MemberExpr>(MCE->getArg(0));
1192 if (!Arg0 || Field != dyn_cast<FieldDecl>(Arg0->getMemberDecl()))
1193 return nullptr;
1194 return Field;
1195 } else if (CallExpr *CE = dyn_cast<CallExpr>(S)) {
1196 FunctionDecl *FD = dyn_cast<FunctionDecl>(CE->getCalleeDecl());
1197 if (!FD || FD->getBuiltinID() != Builtin::BI__builtin_memcpy)
1198 return nullptr;
1199 Expr *DstPtr = CE->getArg(0);
1200 if (ImplicitCastExpr *DC = dyn_cast<ImplicitCastExpr>(DstPtr))
1201 DstPtr = DC->getSubExpr();
1202 UnaryOperator *DUO = dyn_cast<UnaryOperator>(DstPtr);
1203 if (!DUO || DUO->getOpcode() != UO_AddrOf)
1204 return nullptr;
1205 MemberExpr *ME = dyn_cast<MemberExpr>(DUO->getSubExpr());
1206 if (!ME)
1207 return nullptr;
1208 FieldDecl *Field = dyn_cast<FieldDecl>(ME->getMemberDecl());
1209 if (!Field || !isMemcpyableField(Field))
1210 return nullptr;
1211 Expr *SrcPtr = CE->getArg(1);
1212 if (ImplicitCastExpr *SC = dyn_cast<ImplicitCastExpr>(SrcPtr))
1213 SrcPtr = SC->getSubExpr();
1214 UnaryOperator *SUO = dyn_cast<UnaryOperator>(SrcPtr);
1215 if (!SUO || SUO->getOpcode() != UO_AddrOf)
1216 return nullptr;
1217 MemberExpr *ME2 = dyn_cast<MemberExpr>(SUO->getSubExpr());
1218 if (!ME2 || Field != dyn_cast<FieldDecl>(ME2->getMemberDecl()))
1219 return nullptr;
1220 return Field;
1221 }
1222
1223 return nullptr;
1224 }
1225
1226 bool AssignmentsMemcpyable;
1227 SmallVector<Stmt*, 16> AggregatedStmts;
1228
1229 public:
AssignmentMemcpyizer(CodeGenFunction & CGF,const CXXMethodDecl * AD,FunctionArgList & Args)1230 AssignmentMemcpyizer(CodeGenFunction &CGF, const CXXMethodDecl *AD,
1231 FunctionArgList &Args)
1232 : FieldMemcpyizer(CGF, AD->getParent(), Args[Args.size() - 1]),
1233 AssignmentsMemcpyable(CGF.getLangOpts().getGC() == LangOptions::NonGC) {
1234 assert(Args.size() == 2);
1235 }
1236
emitAssignment(Stmt * S)1237 void emitAssignment(Stmt *S) {
1238 FieldDecl *F = getMemcpyableField(S);
1239 if (F) {
1240 addMemcpyableField(F);
1241 AggregatedStmts.push_back(S);
1242 } else {
1243 emitAggregatedStmts();
1244 CGF.EmitStmt(S);
1245 }
1246 }
1247
emitAggregatedStmts()1248 void emitAggregatedStmts() {
1249 if (AggregatedStmts.size() <= 1) {
1250 if (!AggregatedStmts.empty()) {
1251 CopyingValueRepresentation CVR(CGF);
1252 CGF.EmitStmt(AggregatedStmts[0]);
1253 }
1254 reset();
1255 }
1256
1257 emitMemcpy();
1258 AggregatedStmts.clear();
1259 }
1260
finish()1261 void finish() {
1262 emitAggregatedStmts();
1263 }
1264 };
1265 } // end anonymous namespace
1266
isInitializerOfDynamicClass(const CXXCtorInitializer * BaseInit)1267 static bool isInitializerOfDynamicClass(const CXXCtorInitializer *BaseInit) {
1268 const Type *BaseType = BaseInit->getBaseClass();
1269 const auto *BaseClassDecl =
1270 cast<CXXRecordDecl>(BaseType->castAs<RecordType>()->getDecl());
1271 return BaseClassDecl->isDynamicClass();
1272 }
1273
1274 /// EmitCtorPrologue - This routine generates necessary code to initialize
1275 /// base classes and non-static data members belonging to this constructor.
EmitCtorPrologue(const CXXConstructorDecl * CD,CXXCtorType CtorType,FunctionArgList & Args)1276 void CodeGenFunction::EmitCtorPrologue(const CXXConstructorDecl *CD,
1277 CXXCtorType CtorType,
1278 FunctionArgList &Args) {
1279 if (CD->isDelegatingConstructor())
1280 return EmitDelegatingCXXConstructorCall(CD, Args);
1281
1282 const CXXRecordDecl *ClassDecl = CD->getParent();
1283
1284 CXXConstructorDecl::init_const_iterator B = CD->init_begin(),
1285 E = CD->init_end();
1286
1287 // Virtual base initializers first, if any. They aren't needed if:
1288 // - This is a base ctor variant
1289 // - There are no vbases
1290 // - The class is abstract, so a complete object of it cannot be constructed
1291 //
1292 // The check for an abstract class is necessary because sema may not have
1293 // marked virtual base destructors referenced.
1294 bool ConstructVBases = CtorType != Ctor_Base &&
1295 ClassDecl->getNumVBases() != 0 &&
1296 !ClassDecl->isAbstract();
1297
1298 // In the Microsoft C++ ABI, there are no constructor variants. Instead, the
1299 // constructor of a class with virtual bases takes an additional parameter to
1300 // conditionally construct the virtual bases. Emit that check here.
1301 llvm::BasicBlock *BaseCtorContinueBB = nullptr;
1302 if (ConstructVBases &&
1303 !CGM.getTarget().getCXXABI().hasConstructorVariants()) {
1304 BaseCtorContinueBB =
1305 CGM.getCXXABI().EmitCtorCompleteObjectHandler(*this, ClassDecl);
1306 assert(BaseCtorContinueBB);
1307 }
1308
1309 llvm::Value *const OldThis = CXXThisValue;
1310 for (; B != E && (*B)->isBaseInitializer() && (*B)->isBaseVirtual(); B++) {
1311 if (!ConstructVBases)
1312 continue;
1313 if (CGM.getCodeGenOpts().StrictVTablePointers &&
1314 CGM.getCodeGenOpts().OptimizationLevel > 0 &&
1315 isInitializerOfDynamicClass(*B))
1316 CXXThisValue = Builder.CreateLaunderInvariantGroup(LoadCXXThis());
1317 EmitBaseInitializer(*this, ClassDecl, *B);
1318 }
1319
1320 if (BaseCtorContinueBB) {
1321 // Complete object handler should continue to the remaining initializers.
1322 Builder.CreateBr(BaseCtorContinueBB);
1323 EmitBlock(BaseCtorContinueBB);
1324 }
1325
1326 // Then, non-virtual base initializers.
1327 for (; B != E && (*B)->isBaseInitializer(); B++) {
1328 assert(!(*B)->isBaseVirtual());
1329
1330 if (CGM.getCodeGenOpts().StrictVTablePointers &&
1331 CGM.getCodeGenOpts().OptimizationLevel > 0 &&
1332 isInitializerOfDynamicClass(*B))
1333 CXXThisValue = Builder.CreateLaunderInvariantGroup(LoadCXXThis());
1334 EmitBaseInitializer(*this, ClassDecl, *B);
1335 }
1336
1337 CXXThisValue = OldThis;
1338
1339 InitializeVTablePointers(ClassDecl);
1340
1341 // And finally, initialize class members.
1342 FieldConstructionScope FCS(*this, LoadCXXThisAddress());
1343 ConstructorMemcpyizer CM(*this, CD, Args);
1344 for (; B != E; B++) {
1345 CXXCtorInitializer *Member = (*B);
1346 assert(!Member->isBaseInitializer());
1347 assert(Member->isAnyMemberInitializer() &&
1348 "Delegating initializer on non-delegating constructor");
1349 CM.addMemberInitializer(Member);
1350 }
1351 CM.finish();
1352 }
1353
1354 static bool
1355 FieldHasTrivialDestructorBody(ASTContext &Context, const FieldDecl *Field);
1356
1357 static bool
HasTrivialDestructorBody(ASTContext & Context,const CXXRecordDecl * BaseClassDecl,const CXXRecordDecl * MostDerivedClassDecl)1358 HasTrivialDestructorBody(ASTContext &Context,
1359 const CXXRecordDecl *BaseClassDecl,
1360 const CXXRecordDecl *MostDerivedClassDecl)
1361 {
1362 // If the destructor is trivial we don't have to check anything else.
1363 if (BaseClassDecl->hasTrivialDestructor())
1364 return true;
1365
1366 if (!BaseClassDecl->getDestructor()->hasTrivialBody())
1367 return false;
1368
1369 // Check fields.
1370 for (const auto *Field : BaseClassDecl->fields())
1371 if (!FieldHasTrivialDestructorBody(Context, Field))
1372 return false;
1373
1374 // Check non-virtual bases.
1375 for (const auto &I : BaseClassDecl->bases()) {
1376 if (I.isVirtual())
1377 continue;
1378
1379 const CXXRecordDecl *NonVirtualBase =
1380 cast<CXXRecordDecl>(I.getType()->castAs<RecordType>()->getDecl());
1381 if (!HasTrivialDestructorBody(Context, NonVirtualBase,
1382 MostDerivedClassDecl))
1383 return false;
1384 }
1385
1386 if (BaseClassDecl == MostDerivedClassDecl) {
1387 // Check virtual bases.
1388 for (const auto &I : BaseClassDecl->vbases()) {
1389 const CXXRecordDecl *VirtualBase =
1390 cast<CXXRecordDecl>(I.getType()->castAs<RecordType>()->getDecl());
1391 if (!HasTrivialDestructorBody(Context, VirtualBase,
1392 MostDerivedClassDecl))
1393 return false;
1394 }
1395 }
1396
1397 return true;
1398 }
1399
1400 static bool
FieldHasTrivialDestructorBody(ASTContext & Context,const FieldDecl * Field)1401 FieldHasTrivialDestructorBody(ASTContext &Context,
1402 const FieldDecl *Field)
1403 {
1404 QualType FieldBaseElementType = Context.getBaseElementType(Field->getType());
1405
1406 const RecordType *RT = FieldBaseElementType->getAs<RecordType>();
1407 if (!RT)
1408 return true;
1409
1410 CXXRecordDecl *FieldClassDecl = cast<CXXRecordDecl>(RT->getDecl());
1411
1412 // The destructor for an implicit anonymous union member is never invoked.
1413 if (FieldClassDecl->isUnion() && FieldClassDecl->isAnonymousStructOrUnion())
1414 return false;
1415
1416 return HasTrivialDestructorBody(Context, FieldClassDecl, FieldClassDecl);
1417 }
1418
1419 /// CanSkipVTablePointerInitialization - Check whether we need to initialize
1420 /// any vtable pointers before calling this destructor.
CanSkipVTablePointerInitialization(CodeGenFunction & CGF,const CXXDestructorDecl * Dtor)1421 static bool CanSkipVTablePointerInitialization(CodeGenFunction &CGF,
1422 const CXXDestructorDecl *Dtor) {
1423 const CXXRecordDecl *ClassDecl = Dtor->getParent();
1424 if (!ClassDecl->isDynamicClass())
1425 return true;
1426
1427 if (!Dtor->hasTrivialBody())
1428 return false;
1429
1430 // Check the fields.
1431 for (const auto *Field : ClassDecl->fields())
1432 if (!FieldHasTrivialDestructorBody(CGF.getContext(), Field))
1433 return false;
1434
1435 return true;
1436 }
1437
1438 /// EmitDestructorBody - Emits the body of the current destructor.
EmitDestructorBody(FunctionArgList & Args)1439 void CodeGenFunction::EmitDestructorBody(FunctionArgList &Args) {
1440 const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CurGD.getDecl());
1441 CXXDtorType DtorType = CurGD.getDtorType();
1442
1443 // For an abstract class, non-base destructors are never used (and can't
1444 // be emitted in general, because vbase dtors may not have been validated
1445 // by Sema), but the Itanium ABI doesn't make them optional and Clang may
1446 // in fact emit references to them from other compilations, so emit them
1447 // as functions containing a trap instruction.
1448 if (DtorType != Dtor_Base && Dtor->getParent()->isAbstract()) {
1449 llvm::CallInst *TrapCall = EmitTrapCall(llvm::Intrinsic::trap);
1450 TrapCall->setDoesNotReturn();
1451 TrapCall->setDoesNotThrow();
1452 Builder.CreateUnreachable();
1453 Builder.ClearInsertionPoint();
1454 return;
1455 }
1456
1457 Stmt *Body = Dtor->getBody();
1458 if (Body)
1459 incrementProfileCounter(Body);
1460
1461 // The call to operator delete in a deleting destructor happens
1462 // outside of the function-try-block, which means it's always
1463 // possible to delegate the destructor body to the complete
1464 // destructor. Do so.
1465 if (DtorType == Dtor_Deleting) {
1466 RunCleanupsScope DtorEpilogue(*this);
1467 EnterDtorCleanups(Dtor, Dtor_Deleting);
1468 if (HaveInsertPoint()) {
1469 QualType ThisTy = Dtor->getThisObjectType();
1470 EmitCXXDestructorCall(Dtor, Dtor_Complete, /*ForVirtualBase=*/false,
1471 /*Delegating=*/false, LoadCXXThisAddress(), ThisTy);
1472 }
1473 return;
1474 }
1475
1476 // If the body is a function-try-block, enter the try before
1477 // anything else.
1478 bool isTryBody = (Body && isa<CXXTryStmt>(Body));
1479 if (isTryBody)
1480 EnterCXXTryStmt(*cast<CXXTryStmt>(Body), true);
1481 EmitAsanPrologueOrEpilogue(false);
1482
1483 // Enter the epilogue cleanups.
1484 RunCleanupsScope DtorEpilogue(*this);
1485
1486 // If this is the complete variant, just invoke the base variant;
1487 // the epilogue will destruct the virtual bases. But we can't do
1488 // this optimization if the body is a function-try-block, because
1489 // we'd introduce *two* handler blocks. In the Microsoft ABI, we
1490 // always delegate because we might not have a definition in this TU.
1491 switch (DtorType) {
1492 case Dtor_Comdat: llvm_unreachable("not expecting a COMDAT");
1493 case Dtor_Deleting: llvm_unreachable("already handled deleting case");
1494
1495 case Dtor_Complete:
1496 assert((Body || getTarget().getCXXABI().isMicrosoft()) &&
1497 "can't emit a dtor without a body for non-Microsoft ABIs");
1498
1499 // Enter the cleanup scopes for virtual bases.
1500 EnterDtorCleanups(Dtor, Dtor_Complete);
1501
1502 if (!isTryBody) {
1503 QualType ThisTy = Dtor->getThisObjectType();
1504 EmitCXXDestructorCall(Dtor, Dtor_Base, /*ForVirtualBase=*/false,
1505 /*Delegating=*/false, LoadCXXThisAddress(), ThisTy);
1506 break;
1507 }
1508
1509 // Fallthrough: act like we're in the base variant.
1510 LLVM_FALLTHROUGH;
1511
1512 case Dtor_Base:
1513 assert(Body);
1514
1515 // Enter the cleanup scopes for fields and non-virtual bases.
1516 EnterDtorCleanups(Dtor, Dtor_Base);
1517
1518 // Initialize the vtable pointers before entering the body.
1519 if (!CanSkipVTablePointerInitialization(*this, Dtor)) {
1520 // Insert the llvm.launder.invariant.group intrinsic before initializing
1521 // the vptrs to cancel any previous assumptions we might have made.
1522 if (CGM.getCodeGenOpts().StrictVTablePointers &&
1523 CGM.getCodeGenOpts().OptimizationLevel > 0)
1524 CXXThisValue = Builder.CreateLaunderInvariantGroup(LoadCXXThis());
1525 InitializeVTablePointers(Dtor->getParent());
1526 }
1527
1528 if (isTryBody)
1529 EmitStmt(cast<CXXTryStmt>(Body)->getTryBlock());
1530 else if (Body)
1531 EmitStmt(Body);
1532 else {
1533 assert(Dtor->isImplicit() && "bodyless dtor not implicit");
1534 // nothing to do besides what's in the epilogue
1535 }
1536 // -fapple-kext must inline any call to this dtor into
1537 // the caller's body.
1538 if (getLangOpts().AppleKext)
1539 CurFn->addFnAttr(llvm::Attribute::AlwaysInline);
1540
1541 break;
1542 }
1543
1544 // Jump out through the epilogue cleanups.
1545 DtorEpilogue.ForceCleanup();
1546
1547 // Exit the try if applicable.
1548 if (isTryBody)
1549 ExitCXXTryStmt(*cast<CXXTryStmt>(Body), true);
1550 }
1551
emitImplicitAssignmentOperatorBody(FunctionArgList & Args)1552 void CodeGenFunction::emitImplicitAssignmentOperatorBody(FunctionArgList &Args) {
1553 const CXXMethodDecl *AssignOp = cast<CXXMethodDecl>(CurGD.getDecl());
1554 const Stmt *RootS = AssignOp->getBody();
1555 assert(isa<CompoundStmt>(RootS) &&
1556 "Body of an implicit assignment operator should be compound stmt.");
1557 const CompoundStmt *RootCS = cast<CompoundStmt>(RootS);
1558
1559 LexicalScope Scope(*this, RootCS->getSourceRange());
1560
1561 incrementProfileCounter(RootCS);
1562 AssignmentMemcpyizer AM(*this, AssignOp, Args);
1563 for (auto *I : RootCS->body())
1564 AM.emitAssignment(I);
1565 AM.finish();
1566 }
1567
1568 namespace {
LoadThisForDtorDelete(CodeGenFunction & CGF,const CXXDestructorDecl * DD)1569 llvm::Value *LoadThisForDtorDelete(CodeGenFunction &CGF,
1570 const CXXDestructorDecl *DD) {
1571 if (Expr *ThisArg = DD->getOperatorDeleteThisArg())
1572 return CGF.EmitScalarExpr(ThisArg);
1573 return CGF.LoadCXXThis();
1574 }
1575
1576 /// Call the operator delete associated with the current destructor.
1577 struct CallDtorDelete final : EHScopeStack::Cleanup {
CallDtorDelete__anondda66ac40411::CallDtorDelete1578 CallDtorDelete() {}
1579
Emit__anondda66ac40411::CallDtorDelete1580 void Emit(CodeGenFunction &CGF, Flags flags) override {
1581 const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CGF.CurCodeDecl);
1582 const CXXRecordDecl *ClassDecl = Dtor->getParent();
1583 CGF.EmitDeleteCall(Dtor->getOperatorDelete(),
1584 LoadThisForDtorDelete(CGF, Dtor),
1585 CGF.getContext().getTagDeclType(ClassDecl));
1586 }
1587 };
1588
EmitConditionalDtorDeleteCall(CodeGenFunction & CGF,llvm::Value * ShouldDeleteCondition,bool ReturnAfterDelete)1589 void EmitConditionalDtorDeleteCall(CodeGenFunction &CGF,
1590 llvm::Value *ShouldDeleteCondition,
1591 bool ReturnAfterDelete) {
1592 llvm::BasicBlock *callDeleteBB = CGF.createBasicBlock("dtor.call_delete");
1593 llvm::BasicBlock *continueBB = CGF.createBasicBlock("dtor.continue");
1594 llvm::Value *ShouldCallDelete
1595 = CGF.Builder.CreateIsNull(ShouldDeleteCondition);
1596 CGF.Builder.CreateCondBr(ShouldCallDelete, continueBB, callDeleteBB);
1597
1598 CGF.EmitBlock(callDeleteBB);
1599 const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CGF.CurCodeDecl);
1600 const CXXRecordDecl *ClassDecl = Dtor->getParent();
1601 CGF.EmitDeleteCall(Dtor->getOperatorDelete(),
1602 LoadThisForDtorDelete(CGF, Dtor),
1603 CGF.getContext().getTagDeclType(ClassDecl));
1604 assert(Dtor->getOperatorDelete()->isDestroyingOperatorDelete() ==
1605 ReturnAfterDelete &&
1606 "unexpected value for ReturnAfterDelete");
1607 if (ReturnAfterDelete)
1608 CGF.EmitBranchThroughCleanup(CGF.ReturnBlock);
1609 else
1610 CGF.Builder.CreateBr(continueBB);
1611
1612 CGF.EmitBlock(continueBB);
1613 }
1614
1615 struct CallDtorDeleteConditional final : EHScopeStack::Cleanup {
1616 llvm::Value *ShouldDeleteCondition;
1617
1618 public:
CallDtorDeleteConditional__anondda66ac40411::CallDtorDeleteConditional1619 CallDtorDeleteConditional(llvm::Value *ShouldDeleteCondition)
1620 : ShouldDeleteCondition(ShouldDeleteCondition) {
1621 assert(ShouldDeleteCondition != nullptr);
1622 }
1623
Emit__anondda66ac40411::CallDtorDeleteConditional1624 void Emit(CodeGenFunction &CGF, Flags flags) override {
1625 EmitConditionalDtorDeleteCall(CGF, ShouldDeleteCondition,
1626 /*ReturnAfterDelete*/false);
1627 }
1628 };
1629
1630 class DestroyField final : public EHScopeStack::Cleanup {
1631 const FieldDecl *field;
1632 CodeGenFunction::Destroyer *destroyer;
1633 bool useEHCleanupForArray;
1634
1635 public:
DestroyField(const FieldDecl * field,CodeGenFunction::Destroyer * destroyer,bool useEHCleanupForArray)1636 DestroyField(const FieldDecl *field, CodeGenFunction::Destroyer *destroyer,
1637 bool useEHCleanupForArray)
1638 : field(field), destroyer(destroyer),
1639 useEHCleanupForArray(useEHCleanupForArray) {}
1640
Emit(CodeGenFunction & CGF,Flags flags)1641 void Emit(CodeGenFunction &CGF, Flags flags) override {
1642 // Find the address of the field.
1643 Address thisValue = CGF.LoadCXXThisAddress();
1644 QualType RecordTy = CGF.getContext().getTagDeclType(field->getParent());
1645 LValue ThisLV = CGF.MakeAddrLValue(thisValue, RecordTy);
1646 LValue LV = CGF.EmitLValueForField(ThisLV, field);
1647 assert(LV.isSimple());
1648
1649 CGF.emitDestroy(LV.getAddress(CGF), field->getType(), destroyer,
1650 flags.isForNormalCleanup() && useEHCleanupForArray);
1651 }
1652 };
1653
EmitSanitizerDtorCallback(CodeGenFunction & CGF,llvm::Value * Ptr,CharUnits::QuantityType PoisonSize)1654 static void EmitSanitizerDtorCallback(CodeGenFunction &CGF, llvm::Value *Ptr,
1655 CharUnits::QuantityType PoisonSize) {
1656 CodeGenFunction::SanitizerScope SanScope(&CGF);
1657 // Pass in void pointer and size of region as arguments to runtime
1658 // function
1659 llvm::Value *Args[] = {CGF.Builder.CreateBitCast(Ptr, CGF.VoidPtrTy),
1660 llvm::ConstantInt::get(CGF.SizeTy, PoisonSize)};
1661
1662 llvm::Type *ArgTypes[] = {CGF.VoidPtrTy, CGF.SizeTy};
1663
1664 llvm::FunctionType *FnType =
1665 llvm::FunctionType::get(CGF.VoidTy, ArgTypes, false);
1666 llvm::FunctionCallee Fn =
1667 CGF.CGM.CreateRuntimeFunction(FnType, "__sanitizer_dtor_callback");
1668 CGF.EmitNounwindRuntimeCall(Fn, Args);
1669 }
1670
1671 class SanitizeDtorMembers final : public EHScopeStack::Cleanup {
1672 const CXXDestructorDecl *Dtor;
1673
1674 public:
SanitizeDtorMembers(const CXXDestructorDecl * Dtor)1675 SanitizeDtorMembers(const CXXDestructorDecl *Dtor) : Dtor(Dtor) {}
1676
1677 // Generate function call for handling object poisoning.
1678 // Disables tail call elimination, to prevent the current stack frame
1679 // from disappearing from the stack trace.
Emit(CodeGenFunction & CGF,Flags flags)1680 void Emit(CodeGenFunction &CGF, Flags flags) override {
1681 const ASTRecordLayout &Layout =
1682 CGF.getContext().getASTRecordLayout(Dtor->getParent());
1683
1684 // Nothing to poison.
1685 if (Layout.getFieldCount() == 0)
1686 return;
1687
1688 // Prevent the current stack frame from disappearing from the stack trace.
1689 CGF.CurFn->addFnAttr("disable-tail-calls", "true");
1690
1691 // Construct pointer to region to begin poisoning, and calculate poison
1692 // size, so that only members declared in this class are poisoned.
1693 ASTContext &Context = CGF.getContext();
1694
1695 const RecordDecl *Decl = Dtor->getParent();
1696 auto Fields = Decl->fields();
1697 auto IsTrivial = [&](const FieldDecl *F) {
1698 return FieldHasTrivialDestructorBody(Context, F);
1699 };
1700
1701 auto IsZeroSize = [&](const FieldDecl *F) {
1702 return F->isZeroSize(Context);
1703 };
1704
1705 // Poison blocks of fields with trivial destructors making sure that block
1706 // begin and end do not point to zero-sized fields. They don't have
1707 // correct offsets so can't be used to calculate poisoning range.
1708 for (auto It = Fields.begin(); It != Fields.end();) {
1709 It = std::find_if(It, Fields.end(), [&](const FieldDecl *F) {
1710 return IsTrivial(F) && !IsZeroSize(F);
1711 });
1712 if (It == Fields.end())
1713 break;
1714 auto Start = It++;
1715 It = std::find_if(It, Fields.end(), [&](const FieldDecl *F) {
1716 return !IsTrivial(F) && !IsZeroSize(F);
1717 });
1718
1719 PoisonMembers(CGF, (*Start)->getFieldIndex(),
1720 It == Fields.end() ? -1 : (*It)->getFieldIndex());
1721 }
1722 }
1723
1724 private:
1725 /// \param layoutStartOffset index of the ASTRecordLayout field to
1726 /// start poisoning (inclusive)
1727 /// \param layoutEndOffset index of the ASTRecordLayout field to
1728 /// end poisoning (exclusive)
PoisonMembers(CodeGenFunction & CGF,unsigned layoutStartOffset,unsigned layoutEndOffset)1729 void PoisonMembers(CodeGenFunction &CGF, unsigned layoutStartOffset,
1730 unsigned layoutEndOffset) {
1731 ASTContext &Context = CGF.getContext();
1732 const ASTRecordLayout &Layout =
1733 Context.getASTRecordLayout(Dtor->getParent());
1734
1735 // It's a first trivia field so it should be at the begining of char,
1736 // still round up start offset just in case.
1737 CharUnits PoisonStart =
1738 Context.toCharUnitsFromBits(Layout.getFieldOffset(layoutStartOffset) +
1739 Context.getCharWidth() - 1);
1740 llvm::ConstantInt *OffsetSizePtr =
1741 llvm::ConstantInt::get(CGF.SizeTy, PoisonStart.getQuantity());
1742
1743 llvm::Value *OffsetPtr = CGF.Builder.CreateGEP(
1744 CGF.Int8Ty,
1745 CGF.Builder.CreateBitCast(CGF.LoadCXXThis(), CGF.Int8PtrTy),
1746 OffsetSizePtr);
1747
1748 CharUnits PoisonEnd;
1749 if (layoutEndOffset >= Layout.getFieldCount()) {
1750 PoisonEnd = Layout.getNonVirtualSize();
1751 } else {
1752 PoisonEnd =
1753 Context.toCharUnitsFromBits(Layout.getFieldOffset(layoutEndOffset));
1754 }
1755 CharUnits PoisonSize = PoisonEnd - PoisonStart;
1756 if (!PoisonSize.isPositive())
1757 return;
1758
1759 EmitSanitizerDtorCallback(CGF, OffsetPtr, PoisonSize.getQuantity());
1760 }
1761 };
1762
1763 class SanitizeDtorVTable final : public EHScopeStack::Cleanup {
1764 const CXXDestructorDecl *Dtor;
1765
1766 public:
SanitizeDtorVTable(const CXXDestructorDecl * Dtor)1767 SanitizeDtorVTable(const CXXDestructorDecl *Dtor) : Dtor(Dtor) {}
1768
1769 // Generate function call for handling vtable pointer poisoning.
Emit(CodeGenFunction & CGF,Flags flags)1770 void Emit(CodeGenFunction &CGF, Flags flags) override {
1771 assert(Dtor->getParent()->isDynamicClass());
1772 (void)Dtor;
1773 ASTContext &Context = CGF.getContext();
1774 // Poison vtable and vtable ptr if they exist for this class.
1775 llvm::Value *VTablePtr = CGF.LoadCXXThis();
1776
1777 CharUnits::QuantityType PoisonSize =
1778 Context.toCharUnitsFromBits(CGF.PointerWidthInBits).getQuantity();
1779 // Pass in void pointer and size of region as arguments to runtime
1780 // function
1781 EmitSanitizerDtorCallback(CGF, VTablePtr, PoisonSize);
1782 }
1783 };
1784 } // end anonymous namespace
1785
1786 /// Emit all code that comes at the end of class's
1787 /// destructor. This is to call destructors on members and base classes
1788 /// in reverse order of their construction.
1789 ///
1790 /// For a deleting destructor, this also handles the case where a destroying
1791 /// operator delete completely overrides the definition.
EnterDtorCleanups(const CXXDestructorDecl * DD,CXXDtorType DtorType)1792 void CodeGenFunction::EnterDtorCleanups(const CXXDestructorDecl *DD,
1793 CXXDtorType DtorType) {
1794 assert((!DD->isTrivial() || DD->hasAttr<DLLExportAttr>()) &&
1795 "Should not emit dtor epilogue for non-exported trivial dtor!");
1796
1797 // The deleting-destructor phase just needs to call the appropriate
1798 // operator delete that Sema picked up.
1799 if (DtorType == Dtor_Deleting) {
1800 assert(DD->getOperatorDelete() &&
1801 "operator delete missing - EnterDtorCleanups");
1802 if (CXXStructorImplicitParamValue) {
1803 // If there is an implicit param to the deleting dtor, it's a boolean
1804 // telling whether this is a deleting destructor.
1805 if (DD->getOperatorDelete()->isDestroyingOperatorDelete())
1806 EmitConditionalDtorDeleteCall(*this, CXXStructorImplicitParamValue,
1807 /*ReturnAfterDelete*/true);
1808 else
1809 EHStack.pushCleanup<CallDtorDeleteConditional>(
1810 NormalAndEHCleanup, CXXStructorImplicitParamValue);
1811 } else {
1812 if (DD->getOperatorDelete()->isDestroyingOperatorDelete()) {
1813 const CXXRecordDecl *ClassDecl = DD->getParent();
1814 EmitDeleteCall(DD->getOperatorDelete(),
1815 LoadThisForDtorDelete(*this, DD),
1816 getContext().getTagDeclType(ClassDecl));
1817 EmitBranchThroughCleanup(ReturnBlock);
1818 } else {
1819 EHStack.pushCleanup<CallDtorDelete>(NormalAndEHCleanup);
1820 }
1821 }
1822 return;
1823 }
1824
1825 const CXXRecordDecl *ClassDecl = DD->getParent();
1826
1827 // Unions have no bases and do not call field destructors.
1828 if (ClassDecl->isUnion())
1829 return;
1830
1831 // The complete-destructor phase just destructs all the virtual bases.
1832 if (DtorType == Dtor_Complete) {
1833 // Poison the vtable pointer such that access after the base
1834 // and member destructors are invoked is invalid.
1835 if (CGM.getCodeGenOpts().SanitizeMemoryUseAfterDtor &&
1836 SanOpts.has(SanitizerKind::Memory) && ClassDecl->getNumVBases() &&
1837 ClassDecl->isPolymorphic())
1838 EHStack.pushCleanup<SanitizeDtorVTable>(NormalAndEHCleanup, DD);
1839
1840 // We push them in the forward order so that they'll be popped in
1841 // the reverse order.
1842 for (const auto &Base : ClassDecl->vbases()) {
1843 auto *BaseClassDecl =
1844 cast<CXXRecordDecl>(Base.getType()->castAs<RecordType>()->getDecl());
1845
1846 // Ignore trivial destructors.
1847 if (BaseClassDecl->hasTrivialDestructor())
1848 continue;
1849
1850 EHStack.pushCleanup<CallBaseDtor>(NormalAndEHCleanup,
1851 BaseClassDecl,
1852 /*BaseIsVirtual*/ true);
1853 }
1854
1855 return;
1856 }
1857
1858 assert(DtorType == Dtor_Base);
1859 // Poison the vtable pointer if it has no virtual bases, but inherits
1860 // virtual functions.
1861 if (CGM.getCodeGenOpts().SanitizeMemoryUseAfterDtor &&
1862 SanOpts.has(SanitizerKind::Memory) && !ClassDecl->getNumVBases() &&
1863 ClassDecl->isPolymorphic())
1864 EHStack.pushCleanup<SanitizeDtorVTable>(NormalAndEHCleanup, DD);
1865
1866 // Destroy non-virtual bases.
1867 for (const auto &Base : ClassDecl->bases()) {
1868 // Ignore virtual bases.
1869 if (Base.isVirtual())
1870 continue;
1871
1872 CXXRecordDecl *BaseClassDecl = Base.getType()->getAsCXXRecordDecl();
1873
1874 // Ignore trivial destructors.
1875 if (BaseClassDecl->hasTrivialDestructor())
1876 continue;
1877
1878 EHStack.pushCleanup<CallBaseDtor>(NormalAndEHCleanup,
1879 BaseClassDecl,
1880 /*BaseIsVirtual*/ false);
1881 }
1882
1883 // Poison fields such that access after their destructors are
1884 // invoked, and before the base class destructor runs, is invalid.
1885 if (CGM.getCodeGenOpts().SanitizeMemoryUseAfterDtor &&
1886 SanOpts.has(SanitizerKind::Memory))
1887 EHStack.pushCleanup<SanitizeDtorMembers>(NormalAndEHCleanup, DD);
1888
1889 // Destroy direct fields.
1890 for (const auto *Field : ClassDecl->fields()) {
1891 QualType type = Field->getType();
1892 QualType::DestructionKind dtorKind = type.isDestructedType();
1893 if (!dtorKind) continue;
1894
1895 // Anonymous union members do not have their destructors called.
1896 const RecordType *RT = type->getAsUnionType();
1897 if (RT && RT->getDecl()->isAnonymousStructOrUnion()) continue;
1898
1899 CleanupKind cleanupKind = getCleanupKind(dtorKind);
1900 EHStack.pushCleanup<DestroyField>(cleanupKind, Field,
1901 getDestroyer(dtorKind),
1902 cleanupKind & EHCleanup);
1903 }
1904 }
1905
1906 /// EmitCXXAggrConstructorCall - Emit a loop to call a particular
1907 /// constructor for each of several members of an array.
1908 ///
1909 /// \param ctor the constructor to call for each element
1910 /// \param arrayType the type of the array to initialize
1911 /// \param arrayBegin an arrayType*
1912 /// \param zeroInitialize true if each element should be
1913 /// zero-initialized before it is constructed
EmitCXXAggrConstructorCall(const CXXConstructorDecl * ctor,const ArrayType * arrayType,Address arrayBegin,const CXXConstructExpr * E,bool NewPointerIsChecked,bool zeroInitialize)1914 void CodeGenFunction::EmitCXXAggrConstructorCall(
1915 const CXXConstructorDecl *ctor, const ArrayType *arrayType,
1916 Address arrayBegin, const CXXConstructExpr *E, bool NewPointerIsChecked,
1917 bool zeroInitialize) {
1918 QualType elementType;
1919 llvm::Value *numElements =
1920 emitArrayLength(arrayType, elementType, arrayBegin);
1921
1922 EmitCXXAggrConstructorCall(ctor, numElements, arrayBegin, E,
1923 NewPointerIsChecked, zeroInitialize);
1924 }
1925
1926 /// EmitCXXAggrConstructorCall - Emit a loop to call a particular
1927 /// constructor for each of several members of an array.
1928 ///
1929 /// \param ctor the constructor to call for each element
1930 /// \param numElements the number of elements in the array;
1931 /// may be zero
1932 /// \param arrayBase a T*, where T is the type constructed by ctor
1933 /// \param zeroInitialize true if each element should be
1934 /// zero-initialized before it is constructed
EmitCXXAggrConstructorCall(const CXXConstructorDecl * ctor,llvm::Value * numElements,Address arrayBase,const CXXConstructExpr * E,bool NewPointerIsChecked,bool zeroInitialize)1935 void CodeGenFunction::EmitCXXAggrConstructorCall(const CXXConstructorDecl *ctor,
1936 llvm::Value *numElements,
1937 Address arrayBase,
1938 const CXXConstructExpr *E,
1939 bool NewPointerIsChecked,
1940 bool zeroInitialize) {
1941 // It's legal for numElements to be zero. This can happen both
1942 // dynamically, because x can be zero in 'new A[x]', and statically,
1943 // because of GCC extensions that permit zero-length arrays. There
1944 // are probably legitimate places where we could assume that this
1945 // doesn't happen, but it's not clear that it's worth it.
1946 llvm::BranchInst *zeroCheckBranch = nullptr;
1947
1948 // Optimize for a constant count.
1949 llvm::ConstantInt *constantCount
1950 = dyn_cast<llvm::ConstantInt>(numElements);
1951 if (constantCount) {
1952 // Just skip out if the constant count is zero.
1953 if (constantCount->isZero()) return;
1954
1955 // Otherwise, emit the check.
1956 } else {
1957 llvm::BasicBlock *loopBB = createBasicBlock("new.ctorloop");
1958 llvm::Value *iszero = Builder.CreateIsNull(numElements, "isempty");
1959 zeroCheckBranch = Builder.CreateCondBr(iszero, loopBB, loopBB);
1960 EmitBlock(loopBB);
1961 }
1962
1963 // Find the end of the array.
1964 llvm::Type *elementType = arrayBase.getElementType();
1965 llvm::Value *arrayBegin = arrayBase.getPointer();
1966 llvm::Value *arrayEnd = Builder.CreateInBoundsGEP(
1967 elementType, arrayBegin, numElements, "arrayctor.end");
1968
1969 // Enter the loop, setting up a phi for the current location to initialize.
1970 llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
1971 llvm::BasicBlock *loopBB = createBasicBlock("arrayctor.loop");
1972 EmitBlock(loopBB);
1973 llvm::PHINode *cur = Builder.CreatePHI(arrayBegin->getType(), 2,
1974 "arrayctor.cur");
1975 cur->addIncoming(arrayBegin, entryBB);
1976
1977 // Inside the loop body, emit the constructor call on the array element.
1978
1979 // The alignment of the base, adjusted by the size of a single element,
1980 // provides a conservative estimate of the alignment of every element.
1981 // (This assumes we never start tracking offsetted alignments.)
1982 //
1983 // Note that these are complete objects and so we don't need to
1984 // use the non-virtual size or alignment.
1985 QualType type = getContext().getTypeDeclType(ctor->getParent());
1986 CharUnits eltAlignment =
1987 arrayBase.getAlignment()
1988 .alignmentOfArrayElement(getContext().getTypeSizeInChars(type));
1989 Address curAddr = Address(cur, eltAlignment);
1990
1991 // Zero initialize the storage, if requested.
1992 if (zeroInitialize)
1993 EmitNullInitialization(curAddr, type);
1994
1995 // C++ [class.temporary]p4:
1996 // There are two contexts in which temporaries are destroyed at a different
1997 // point than the end of the full-expression. The first context is when a
1998 // default constructor is called to initialize an element of an array.
1999 // If the constructor has one or more default arguments, the destruction of
2000 // every temporary created in a default argument expression is sequenced
2001 // before the construction of the next array element, if any.
2002
2003 {
2004 RunCleanupsScope Scope(*this);
2005
2006 // Evaluate the constructor and its arguments in a regular
2007 // partial-destroy cleanup.
2008 if (getLangOpts().Exceptions &&
2009 !ctor->getParent()->hasTrivialDestructor()) {
2010 Destroyer *destroyer = destroyCXXObject;
2011 pushRegularPartialArrayCleanup(arrayBegin, cur, type, eltAlignment,
2012 *destroyer);
2013 }
2014 auto currAVS = AggValueSlot::forAddr(
2015 curAddr, type.getQualifiers(), AggValueSlot::IsDestructed,
2016 AggValueSlot::DoesNotNeedGCBarriers, AggValueSlot::IsNotAliased,
2017 AggValueSlot::DoesNotOverlap, AggValueSlot::IsNotZeroed,
2018 NewPointerIsChecked ? AggValueSlot::IsSanitizerChecked
2019 : AggValueSlot::IsNotSanitizerChecked);
2020 EmitCXXConstructorCall(ctor, Ctor_Complete, /*ForVirtualBase=*/false,
2021 /*Delegating=*/false, currAVS, E);
2022 }
2023
2024 // Go to the next element.
2025 llvm::Value *next = Builder.CreateInBoundsGEP(
2026 elementType, cur, llvm::ConstantInt::get(SizeTy, 1), "arrayctor.next");
2027 cur->addIncoming(next, Builder.GetInsertBlock());
2028
2029 // Check whether that's the end of the loop.
2030 llvm::Value *done = Builder.CreateICmpEQ(next, arrayEnd, "arrayctor.done");
2031 llvm::BasicBlock *contBB = createBasicBlock("arrayctor.cont");
2032 Builder.CreateCondBr(done, contBB, loopBB);
2033
2034 // Patch the earlier check to skip over the loop.
2035 if (zeroCheckBranch) zeroCheckBranch->setSuccessor(0, contBB);
2036
2037 EmitBlock(contBB);
2038 }
2039
destroyCXXObject(CodeGenFunction & CGF,Address addr,QualType type)2040 void CodeGenFunction::destroyCXXObject(CodeGenFunction &CGF,
2041 Address addr,
2042 QualType type) {
2043 const RecordType *rtype = type->castAs<RecordType>();
2044 const CXXRecordDecl *record = cast<CXXRecordDecl>(rtype->getDecl());
2045 const CXXDestructorDecl *dtor = record->getDestructor();
2046 assert(!dtor->isTrivial());
2047 CGF.EmitCXXDestructorCall(dtor, Dtor_Complete, /*for vbase*/ false,
2048 /*Delegating=*/false, addr, type);
2049 }
2050
EmitCXXConstructorCall(const CXXConstructorDecl * D,CXXCtorType Type,bool ForVirtualBase,bool Delegating,AggValueSlot ThisAVS,const CXXConstructExpr * E)2051 void CodeGenFunction::EmitCXXConstructorCall(const CXXConstructorDecl *D,
2052 CXXCtorType Type,
2053 bool ForVirtualBase,
2054 bool Delegating,
2055 AggValueSlot ThisAVS,
2056 const CXXConstructExpr *E) {
2057 CallArgList Args;
2058 Address This = ThisAVS.getAddress();
2059 LangAS SlotAS = ThisAVS.getQualifiers().getAddressSpace();
2060 QualType ThisType = D->getThisType();
2061 LangAS ThisAS = ThisType.getTypePtr()->getPointeeType().getAddressSpace();
2062 llvm::Value *ThisPtr = This.getPointer();
2063
2064 if (SlotAS != ThisAS) {
2065 unsigned TargetThisAS = getContext().getTargetAddressSpace(ThisAS);
2066 llvm::Type *NewType =
2067 ThisPtr->getType()->getPointerElementType()->getPointerTo(TargetThisAS);
2068 ThisPtr = getTargetHooks().performAddrSpaceCast(*this, This.getPointer(),
2069 ThisAS, SlotAS, NewType);
2070 }
2071
2072 // Push the this ptr.
2073 Args.add(RValue::get(ThisPtr), D->getThisType());
2074
2075 // If this is a trivial constructor, emit a memcpy now before we lose
2076 // the alignment information on the argument.
2077 // FIXME: It would be better to preserve alignment information into CallArg.
2078 if (isMemcpyEquivalentSpecialMember(D)) {
2079 assert(E->getNumArgs() == 1 && "unexpected argcount for trivial ctor");
2080
2081 const Expr *Arg = E->getArg(0);
2082 LValue Src = EmitLValue(Arg);
2083 QualType DestTy = getContext().getTypeDeclType(D->getParent());
2084 LValue Dest = MakeAddrLValue(This, DestTy);
2085 EmitAggregateCopyCtor(Dest, Src, ThisAVS.mayOverlap());
2086 return;
2087 }
2088
2089 // Add the rest of the user-supplied arguments.
2090 const FunctionProtoType *FPT = D->getType()->castAs<FunctionProtoType>();
2091 EvaluationOrder Order = E->isListInitialization()
2092 ? EvaluationOrder::ForceLeftToRight
2093 : EvaluationOrder::Default;
2094 EmitCallArgs(Args, FPT, E->arguments(), E->getConstructor(),
2095 /*ParamsToSkip*/ 0, Order);
2096
2097 EmitCXXConstructorCall(D, Type, ForVirtualBase, Delegating, This, Args,
2098 ThisAVS.mayOverlap(), E->getExprLoc(),
2099 ThisAVS.isSanitizerChecked());
2100 }
2101
canEmitDelegateCallArgs(CodeGenFunction & CGF,const CXXConstructorDecl * Ctor,CXXCtorType Type,CallArgList & Args)2102 static bool canEmitDelegateCallArgs(CodeGenFunction &CGF,
2103 const CXXConstructorDecl *Ctor,
2104 CXXCtorType Type, CallArgList &Args) {
2105 // We can't forward a variadic call.
2106 if (Ctor->isVariadic())
2107 return false;
2108
2109 if (CGF.getTarget().getCXXABI().areArgsDestroyedLeftToRightInCallee()) {
2110 // If the parameters are callee-cleanup, it's not safe to forward.
2111 for (auto *P : Ctor->parameters())
2112 if (P->needsDestruction(CGF.getContext()))
2113 return false;
2114
2115 // Likewise if they're inalloca.
2116 const CGFunctionInfo &Info =
2117 CGF.CGM.getTypes().arrangeCXXConstructorCall(Args, Ctor, Type, 0, 0);
2118 if (Info.usesInAlloca())
2119 return false;
2120 }
2121
2122 // Anything else should be OK.
2123 return true;
2124 }
2125
EmitCXXConstructorCall(const CXXConstructorDecl * D,CXXCtorType Type,bool ForVirtualBase,bool Delegating,Address This,CallArgList & Args,AggValueSlot::Overlap_t Overlap,SourceLocation Loc,bool NewPointerIsChecked)2126 void CodeGenFunction::EmitCXXConstructorCall(const CXXConstructorDecl *D,
2127 CXXCtorType Type,
2128 bool ForVirtualBase,
2129 bool Delegating,
2130 Address This,
2131 CallArgList &Args,
2132 AggValueSlot::Overlap_t Overlap,
2133 SourceLocation Loc,
2134 bool NewPointerIsChecked) {
2135 const CXXRecordDecl *ClassDecl = D->getParent();
2136
2137 if (!NewPointerIsChecked)
2138 EmitTypeCheck(CodeGenFunction::TCK_ConstructorCall, Loc, This.getPointer(),
2139 getContext().getRecordType(ClassDecl), CharUnits::Zero());
2140
2141 if (D->isTrivial() && D->isDefaultConstructor()) {
2142 assert(Args.size() == 1 && "trivial default ctor with args");
2143 return;
2144 }
2145
2146 // If this is a trivial constructor, just emit what's needed. If this is a
2147 // union copy constructor, we must emit a memcpy, because the AST does not
2148 // model that copy.
2149 if (isMemcpyEquivalentSpecialMember(D)) {
2150 assert(Args.size() == 2 && "unexpected argcount for trivial ctor");
2151
2152 QualType SrcTy = D->getParamDecl(0)->getType().getNonReferenceType();
2153 Address Src(Args[1].getRValue(*this).getScalarVal(),
2154 CGM.getNaturalTypeAlignment(SrcTy));
2155 LValue SrcLVal = MakeAddrLValue(Src, SrcTy);
2156 QualType DestTy = getContext().getTypeDeclType(ClassDecl);
2157 LValue DestLVal = MakeAddrLValue(This, DestTy);
2158 EmitAggregateCopyCtor(DestLVal, SrcLVal, Overlap);
2159 return;
2160 }
2161
2162 bool PassPrototypeArgs = true;
2163 // Check whether we can actually emit the constructor before trying to do so.
2164 if (auto Inherited = D->getInheritedConstructor()) {
2165 PassPrototypeArgs = getTypes().inheritingCtorHasParams(Inherited, Type);
2166 if (PassPrototypeArgs && !canEmitDelegateCallArgs(*this, D, Type, Args)) {
2167 EmitInlinedInheritingCXXConstructorCall(D, Type, ForVirtualBase,
2168 Delegating, Args);
2169 return;
2170 }
2171 }
2172
2173 // Insert any ABI-specific implicit constructor arguments.
2174 CGCXXABI::AddedStructorArgCounts ExtraArgs =
2175 CGM.getCXXABI().addImplicitConstructorArgs(*this, D, Type, ForVirtualBase,
2176 Delegating, Args);
2177
2178 // Emit the call.
2179 llvm::Constant *CalleePtr = CGM.getAddrOfCXXStructor(GlobalDecl(D, Type));
2180 const CGFunctionInfo &Info = CGM.getTypes().arrangeCXXConstructorCall(
2181 Args, D, Type, ExtraArgs.Prefix, ExtraArgs.Suffix, PassPrototypeArgs);
2182 CGCallee Callee = CGCallee::forDirect(CalleePtr, GlobalDecl(D, Type));
2183 EmitCall(Info, Callee, ReturnValueSlot(), Args, nullptr, false, Loc);
2184
2185 // Generate vtable assumptions if we're constructing a complete object
2186 // with a vtable. We don't do this for base subobjects for two reasons:
2187 // first, it's incorrect for classes with virtual bases, and second, we're
2188 // about to overwrite the vptrs anyway.
2189 // We also have to make sure if we can refer to vtable:
2190 // - Otherwise we can refer to vtable if it's safe to speculatively emit.
2191 // FIXME: If vtable is used by ctor/dtor, or if vtable is external and we are
2192 // sure that definition of vtable is not hidden,
2193 // then we are always safe to refer to it.
2194 // FIXME: It looks like InstCombine is very inefficient on dealing with
2195 // assumes. Make assumption loads require -fstrict-vtable-pointers temporarily.
2196 if (CGM.getCodeGenOpts().OptimizationLevel > 0 &&
2197 ClassDecl->isDynamicClass() && Type != Ctor_Base &&
2198 CGM.getCXXABI().canSpeculativelyEmitVTable(ClassDecl) &&
2199 CGM.getCodeGenOpts().StrictVTablePointers)
2200 EmitVTableAssumptionLoads(ClassDecl, This);
2201 }
2202
EmitInheritedCXXConstructorCall(const CXXConstructorDecl * D,bool ForVirtualBase,Address This,bool InheritedFromVBase,const CXXInheritedCtorInitExpr * E)2203 void CodeGenFunction::EmitInheritedCXXConstructorCall(
2204 const CXXConstructorDecl *D, bool ForVirtualBase, Address This,
2205 bool InheritedFromVBase, const CXXInheritedCtorInitExpr *E) {
2206 CallArgList Args;
2207 CallArg ThisArg(RValue::get(This.getPointer()), D->getThisType());
2208
2209 // Forward the parameters.
2210 if (InheritedFromVBase &&
2211 CGM.getTarget().getCXXABI().hasConstructorVariants()) {
2212 // Nothing to do; this construction is not responsible for constructing
2213 // the base class containing the inherited constructor.
2214 // FIXME: Can we just pass undef's for the remaining arguments if we don't
2215 // have constructor variants?
2216 Args.push_back(ThisArg);
2217 } else if (!CXXInheritedCtorInitExprArgs.empty()) {
2218 // The inheriting constructor was inlined; just inject its arguments.
2219 assert(CXXInheritedCtorInitExprArgs.size() >= D->getNumParams() &&
2220 "wrong number of parameters for inherited constructor call");
2221 Args = CXXInheritedCtorInitExprArgs;
2222 Args[0] = ThisArg;
2223 } else {
2224 // The inheriting constructor was not inlined. Emit delegating arguments.
2225 Args.push_back(ThisArg);
2226 const auto *OuterCtor = cast<CXXConstructorDecl>(CurCodeDecl);
2227 assert(OuterCtor->getNumParams() == D->getNumParams());
2228 assert(!OuterCtor->isVariadic() && "should have been inlined");
2229
2230 for (const auto *Param : OuterCtor->parameters()) {
2231 assert(getContext().hasSameUnqualifiedType(
2232 OuterCtor->getParamDecl(Param->getFunctionScopeIndex())->getType(),
2233 Param->getType()));
2234 EmitDelegateCallArg(Args, Param, E->getLocation());
2235
2236 // Forward __attribute__(pass_object_size).
2237 if (Param->hasAttr<PassObjectSizeAttr>()) {
2238 auto *POSParam = SizeArguments[Param];
2239 assert(POSParam && "missing pass_object_size value for forwarding");
2240 EmitDelegateCallArg(Args, POSParam, E->getLocation());
2241 }
2242 }
2243 }
2244
2245 EmitCXXConstructorCall(D, Ctor_Base, ForVirtualBase, /*Delegating*/false,
2246 This, Args, AggValueSlot::MayOverlap,
2247 E->getLocation(), /*NewPointerIsChecked*/true);
2248 }
2249
EmitInlinedInheritingCXXConstructorCall(const CXXConstructorDecl * Ctor,CXXCtorType CtorType,bool ForVirtualBase,bool Delegating,CallArgList & Args)2250 void CodeGenFunction::EmitInlinedInheritingCXXConstructorCall(
2251 const CXXConstructorDecl *Ctor, CXXCtorType CtorType, bool ForVirtualBase,
2252 bool Delegating, CallArgList &Args) {
2253 GlobalDecl GD(Ctor, CtorType);
2254 InlinedInheritingConstructorScope Scope(*this, GD);
2255 ApplyInlineDebugLocation DebugScope(*this, GD);
2256 RunCleanupsScope RunCleanups(*this);
2257
2258 // Save the arguments to be passed to the inherited constructor.
2259 CXXInheritedCtorInitExprArgs = Args;
2260
2261 FunctionArgList Params;
2262 QualType RetType = BuildFunctionArgList(CurGD, Params);
2263 FnRetTy = RetType;
2264
2265 // Insert any ABI-specific implicit constructor arguments.
2266 CGM.getCXXABI().addImplicitConstructorArgs(*this, Ctor, CtorType,
2267 ForVirtualBase, Delegating, Args);
2268
2269 // Emit a simplified prolog. We only need to emit the implicit params.
2270 assert(Args.size() >= Params.size() && "too few arguments for call");
2271 for (unsigned I = 0, N = Args.size(); I != N; ++I) {
2272 if (I < Params.size() && isa<ImplicitParamDecl>(Params[I])) {
2273 const RValue &RV = Args[I].getRValue(*this);
2274 assert(!RV.isComplex() && "complex indirect params not supported");
2275 ParamValue Val = RV.isScalar()
2276 ? ParamValue::forDirect(RV.getScalarVal())
2277 : ParamValue::forIndirect(RV.getAggregateAddress());
2278 EmitParmDecl(*Params[I], Val, I + 1);
2279 }
2280 }
2281
2282 // Create a return value slot if the ABI implementation wants one.
2283 // FIXME: This is dumb, we should ask the ABI not to try to set the return
2284 // value instead.
2285 if (!RetType->isVoidType())
2286 ReturnValue = CreateIRTemp(RetType, "retval.inhctor");
2287
2288 CGM.getCXXABI().EmitInstanceFunctionProlog(*this);
2289 CXXThisValue = CXXABIThisValue;
2290
2291 // Directly emit the constructor initializers.
2292 EmitCtorPrologue(Ctor, CtorType, Params);
2293 }
2294
EmitVTableAssumptionLoad(const VPtr & Vptr,Address This)2295 void CodeGenFunction::EmitVTableAssumptionLoad(const VPtr &Vptr, Address This) {
2296 llvm::Value *VTableGlobal =
2297 CGM.getCXXABI().getVTableAddressPoint(Vptr.Base, Vptr.VTableClass);
2298 if (!VTableGlobal)
2299 return;
2300
2301 // We can just use the base offset in the complete class.
2302 CharUnits NonVirtualOffset = Vptr.Base.getBaseOffset();
2303
2304 if (!NonVirtualOffset.isZero())
2305 This =
2306 ApplyNonVirtualAndVirtualOffset(*this, This, NonVirtualOffset, nullptr,
2307 Vptr.VTableClass, Vptr.NearestVBase);
2308
2309 llvm::Value *VPtrValue =
2310 GetVTablePtr(This, VTableGlobal->getType(), Vptr.VTableClass);
2311 llvm::Value *Cmp =
2312 Builder.CreateICmpEQ(VPtrValue, VTableGlobal, "cmp.vtables");
2313 Builder.CreateAssumption(Cmp);
2314 }
2315
EmitVTableAssumptionLoads(const CXXRecordDecl * ClassDecl,Address This)2316 void CodeGenFunction::EmitVTableAssumptionLoads(const CXXRecordDecl *ClassDecl,
2317 Address This) {
2318 if (CGM.getCXXABI().doStructorsInitializeVPtrs(ClassDecl))
2319 for (const VPtr &Vptr : getVTablePointers(ClassDecl))
2320 EmitVTableAssumptionLoad(Vptr, This);
2321 }
2322
2323 void
EmitSynthesizedCXXCopyCtorCall(const CXXConstructorDecl * D,Address This,Address Src,const CXXConstructExpr * E)2324 CodeGenFunction::EmitSynthesizedCXXCopyCtorCall(const CXXConstructorDecl *D,
2325 Address This, Address Src,
2326 const CXXConstructExpr *E) {
2327 const FunctionProtoType *FPT = D->getType()->castAs<FunctionProtoType>();
2328
2329 CallArgList Args;
2330
2331 // Push the this ptr.
2332 Args.add(RValue::get(This.getPointer()), D->getThisType());
2333
2334 // Push the src ptr.
2335 QualType QT = *(FPT->param_type_begin());
2336 llvm::Type *t = CGM.getTypes().ConvertType(QT);
2337 Src = Builder.CreateBitCast(Src, t);
2338 Args.add(RValue::get(Src.getPointer()), QT);
2339
2340 // Skip over first argument (Src).
2341 EmitCallArgs(Args, FPT, drop_begin(E->arguments(), 1), E->getConstructor(),
2342 /*ParamsToSkip*/ 1);
2343
2344 EmitCXXConstructorCall(D, Ctor_Complete, /*ForVirtualBase*/false,
2345 /*Delegating*/false, This, Args,
2346 AggValueSlot::MayOverlap, E->getExprLoc(),
2347 /*NewPointerIsChecked*/false);
2348 }
2349
2350 void
EmitDelegateCXXConstructorCall(const CXXConstructorDecl * Ctor,CXXCtorType CtorType,const FunctionArgList & Args,SourceLocation Loc)2351 CodeGenFunction::EmitDelegateCXXConstructorCall(const CXXConstructorDecl *Ctor,
2352 CXXCtorType CtorType,
2353 const FunctionArgList &Args,
2354 SourceLocation Loc) {
2355 CallArgList DelegateArgs;
2356
2357 FunctionArgList::const_iterator I = Args.begin(), E = Args.end();
2358 assert(I != E && "no parameters to constructor");
2359
2360 // this
2361 Address This = LoadCXXThisAddress();
2362 DelegateArgs.add(RValue::get(This.getPointer()), (*I)->getType());
2363 ++I;
2364
2365 // FIXME: The location of the VTT parameter in the parameter list is
2366 // specific to the Itanium ABI and shouldn't be hardcoded here.
2367 if (CGM.getCXXABI().NeedsVTTParameter(CurGD)) {
2368 assert(I != E && "cannot skip vtt parameter, already done with args");
2369 assert((*I)->getType()->isPointerType() &&
2370 "skipping parameter not of vtt type");
2371 ++I;
2372 }
2373
2374 // Explicit arguments.
2375 for (; I != E; ++I) {
2376 const VarDecl *param = *I;
2377 // FIXME: per-argument source location
2378 EmitDelegateCallArg(DelegateArgs, param, Loc);
2379 }
2380
2381 EmitCXXConstructorCall(Ctor, CtorType, /*ForVirtualBase=*/false,
2382 /*Delegating=*/true, This, DelegateArgs,
2383 AggValueSlot::MayOverlap, Loc,
2384 /*NewPointerIsChecked=*/true);
2385 }
2386
2387 namespace {
2388 struct CallDelegatingCtorDtor final : EHScopeStack::Cleanup {
2389 const CXXDestructorDecl *Dtor;
2390 Address Addr;
2391 CXXDtorType Type;
2392
CallDelegatingCtorDtor__anondda66ac40911::CallDelegatingCtorDtor2393 CallDelegatingCtorDtor(const CXXDestructorDecl *D, Address Addr,
2394 CXXDtorType Type)
2395 : Dtor(D), Addr(Addr), Type(Type) {}
2396
Emit__anondda66ac40911::CallDelegatingCtorDtor2397 void Emit(CodeGenFunction &CGF, Flags flags) override {
2398 // We are calling the destructor from within the constructor.
2399 // Therefore, "this" should have the expected type.
2400 QualType ThisTy = Dtor->getThisObjectType();
2401 CGF.EmitCXXDestructorCall(Dtor, Type, /*ForVirtualBase=*/false,
2402 /*Delegating=*/true, Addr, ThisTy);
2403 }
2404 };
2405 } // end anonymous namespace
2406
2407 void
EmitDelegatingCXXConstructorCall(const CXXConstructorDecl * Ctor,const FunctionArgList & Args)2408 CodeGenFunction::EmitDelegatingCXXConstructorCall(const CXXConstructorDecl *Ctor,
2409 const FunctionArgList &Args) {
2410 assert(Ctor->isDelegatingConstructor());
2411
2412 Address ThisPtr = LoadCXXThisAddress();
2413
2414 AggValueSlot AggSlot =
2415 AggValueSlot::forAddr(ThisPtr, Qualifiers(),
2416 AggValueSlot::IsDestructed,
2417 AggValueSlot::DoesNotNeedGCBarriers,
2418 AggValueSlot::IsNotAliased,
2419 AggValueSlot::MayOverlap,
2420 AggValueSlot::IsNotZeroed,
2421 // Checks are made by the code that calls constructor.
2422 AggValueSlot::IsSanitizerChecked);
2423
2424 EmitAggExpr(Ctor->init_begin()[0]->getInit(), AggSlot);
2425
2426 const CXXRecordDecl *ClassDecl = Ctor->getParent();
2427 if (CGM.getLangOpts().Exceptions && !ClassDecl->hasTrivialDestructor()) {
2428 CXXDtorType Type =
2429 CurGD.getCtorType() == Ctor_Complete ? Dtor_Complete : Dtor_Base;
2430
2431 EHStack.pushCleanup<CallDelegatingCtorDtor>(EHCleanup,
2432 ClassDecl->getDestructor(),
2433 ThisPtr, Type);
2434 }
2435 }
2436
EmitCXXDestructorCall(const CXXDestructorDecl * DD,CXXDtorType Type,bool ForVirtualBase,bool Delegating,Address This,QualType ThisTy)2437 void CodeGenFunction::EmitCXXDestructorCall(const CXXDestructorDecl *DD,
2438 CXXDtorType Type,
2439 bool ForVirtualBase,
2440 bool Delegating, Address This,
2441 QualType ThisTy) {
2442 CGM.getCXXABI().EmitDestructorCall(*this, DD, Type, ForVirtualBase,
2443 Delegating, This, ThisTy);
2444 }
2445
2446 namespace {
2447 struct CallLocalDtor final : EHScopeStack::Cleanup {
2448 const CXXDestructorDecl *Dtor;
2449 Address Addr;
2450 QualType Ty;
2451
CallLocalDtor__anondda66ac40a11::CallLocalDtor2452 CallLocalDtor(const CXXDestructorDecl *D, Address Addr, QualType Ty)
2453 : Dtor(D), Addr(Addr), Ty(Ty) {}
2454
Emit__anondda66ac40a11::CallLocalDtor2455 void Emit(CodeGenFunction &CGF, Flags flags) override {
2456 CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
2457 /*ForVirtualBase=*/false,
2458 /*Delegating=*/false, Addr, Ty);
2459 }
2460 };
2461 } // end anonymous namespace
2462
PushDestructorCleanup(const CXXDestructorDecl * D,QualType T,Address Addr)2463 void CodeGenFunction::PushDestructorCleanup(const CXXDestructorDecl *D,
2464 QualType T, Address Addr) {
2465 EHStack.pushCleanup<CallLocalDtor>(NormalAndEHCleanup, D, Addr, T);
2466 }
2467
PushDestructorCleanup(QualType T,Address Addr)2468 void CodeGenFunction::PushDestructorCleanup(QualType T, Address Addr) {
2469 CXXRecordDecl *ClassDecl = T->getAsCXXRecordDecl();
2470 if (!ClassDecl) return;
2471 if (ClassDecl->hasTrivialDestructor()) return;
2472
2473 const CXXDestructorDecl *D = ClassDecl->getDestructor();
2474 assert(D && D->isUsed() && "destructor not marked as used!");
2475 PushDestructorCleanup(D, T, Addr);
2476 }
2477
InitializeVTablePointer(const VPtr & Vptr)2478 void CodeGenFunction::InitializeVTablePointer(const VPtr &Vptr) {
2479 // Compute the address point.
2480 llvm::Value *VTableAddressPoint =
2481 CGM.getCXXABI().getVTableAddressPointInStructor(
2482 *this, Vptr.VTableClass, Vptr.Base, Vptr.NearestVBase);
2483
2484 if (!VTableAddressPoint)
2485 return;
2486
2487 // Compute where to store the address point.
2488 llvm::Value *VirtualOffset = nullptr;
2489 CharUnits NonVirtualOffset = CharUnits::Zero();
2490
2491 if (CGM.getCXXABI().isVirtualOffsetNeededForVTableField(*this, Vptr)) {
2492 // We need to use the virtual base offset offset because the virtual base
2493 // might have a different offset in the most derived class.
2494
2495 VirtualOffset = CGM.getCXXABI().GetVirtualBaseClassOffset(
2496 *this, LoadCXXThisAddress(), Vptr.VTableClass, Vptr.NearestVBase);
2497 NonVirtualOffset = Vptr.OffsetFromNearestVBase;
2498 } else {
2499 // We can just use the base offset in the complete class.
2500 NonVirtualOffset = Vptr.Base.getBaseOffset();
2501 }
2502
2503 // Apply the offsets.
2504 Address VTableField = LoadCXXThisAddress();
2505
2506 if (!NonVirtualOffset.isZero() || VirtualOffset)
2507 VTableField = ApplyNonVirtualAndVirtualOffset(
2508 *this, VTableField, NonVirtualOffset, VirtualOffset, Vptr.VTableClass,
2509 Vptr.NearestVBase);
2510
2511 // Finally, store the address point. Use the same LLVM types as the field to
2512 // support optimization.
2513 unsigned GlobalsAS = CGM.getDataLayout().getDefaultGlobalsAddressSpace();
2514 unsigned ProgAS = CGM.getDataLayout().getProgramAddressSpace();
2515 llvm::Type *VTablePtrTy =
2516 llvm::FunctionType::get(CGM.Int32Ty, /*isVarArg=*/true)
2517 ->getPointerTo(ProgAS)
2518 ->getPointerTo(GlobalsAS);
2519 // vtable field is is derived from `this` pointer, therefore it should be in
2520 // default address space.
2521 VTableField = Builder.CreatePointerBitCastOrAddrSpaceCast(
2522 VTableField, VTablePtrTy->getPointerTo());
2523 VTableAddressPoint = Builder.CreatePointerBitCastOrAddrSpaceCast(
2524 VTableAddressPoint, VTablePtrTy);
2525
2526 llvm::StoreInst *Store = Builder.CreateStore(VTableAddressPoint, VTableField);
2527 TBAAAccessInfo TBAAInfo = CGM.getTBAAVTablePtrAccessInfo(VTablePtrTy);
2528 CGM.DecorateInstructionWithTBAA(Store, TBAAInfo);
2529 if (CGM.getCodeGenOpts().OptimizationLevel > 0 &&
2530 CGM.getCodeGenOpts().StrictVTablePointers)
2531 CGM.DecorateInstructionWithInvariantGroup(Store, Vptr.VTableClass);
2532 }
2533
2534 CodeGenFunction::VPtrsVector
getVTablePointers(const CXXRecordDecl * VTableClass)2535 CodeGenFunction::getVTablePointers(const CXXRecordDecl *VTableClass) {
2536 CodeGenFunction::VPtrsVector VPtrsResult;
2537 VisitedVirtualBasesSetTy VBases;
2538 getVTablePointers(BaseSubobject(VTableClass, CharUnits::Zero()),
2539 /*NearestVBase=*/nullptr,
2540 /*OffsetFromNearestVBase=*/CharUnits::Zero(),
2541 /*BaseIsNonVirtualPrimaryBase=*/false, VTableClass, VBases,
2542 VPtrsResult);
2543 return VPtrsResult;
2544 }
2545
getVTablePointers(BaseSubobject Base,const CXXRecordDecl * NearestVBase,CharUnits OffsetFromNearestVBase,bool BaseIsNonVirtualPrimaryBase,const CXXRecordDecl * VTableClass,VisitedVirtualBasesSetTy & VBases,VPtrsVector & Vptrs)2546 void CodeGenFunction::getVTablePointers(BaseSubobject Base,
2547 const CXXRecordDecl *NearestVBase,
2548 CharUnits OffsetFromNearestVBase,
2549 bool BaseIsNonVirtualPrimaryBase,
2550 const CXXRecordDecl *VTableClass,
2551 VisitedVirtualBasesSetTy &VBases,
2552 VPtrsVector &Vptrs) {
2553 // If this base is a non-virtual primary base the address point has already
2554 // been set.
2555 if (!BaseIsNonVirtualPrimaryBase) {
2556 // Initialize the vtable pointer for this base.
2557 VPtr Vptr = {Base, NearestVBase, OffsetFromNearestVBase, VTableClass};
2558 Vptrs.push_back(Vptr);
2559 }
2560
2561 const CXXRecordDecl *RD = Base.getBase();
2562
2563 // Traverse bases.
2564 for (const auto &I : RD->bases()) {
2565 auto *BaseDecl =
2566 cast<CXXRecordDecl>(I.getType()->castAs<RecordType>()->getDecl());
2567
2568 // Ignore classes without a vtable.
2569 if (!BaseDecl->isDynamicClass())
2570 continue;
2571
2572 CharUnits BaseOffset;
2573 CharUnits BaseOffsetFromNearestVBase;
2574 bool BaseDeclIsNonVirtualPrimaryBase;
2575
2576 if (I.isVirtual()) {
2577 // Check if we've visited this virtual base before.
2578 if (!VBases.insert(BaseDecl).second)
2579 continue;
2580
2581 const ASTRecordLayout &Layout =
2582 getContext().getASTRecordLayout(VTableClass);
2583
2584 BaseOffset = Layout.getVBaseClassOffset(BaseDecl);
2585 BaseOffsetFromNearestVBase = CharUnits::Zero();
2586 BaseDeclIsNonVirtualPrimaryBase = false;
2587 } else {
2588 const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
2589
2590 BaseOffset = Base.getBaseOffset() + Layout.getBaseClassOffset(BaseDecl);
2591 BaseOffsetFromNearestVBase =
2592 OffsetFromNearestVBase + Layout.getBaseClassOffset(BaseDecl);
2593 BaseDeclIsNonVirtualPrimaryBase = Layout.getPrimaryBase() == BaseDecl;
2594 }
2595
2596 getVTablePointers(
2597 BaseSubobject(BaseDecl, BaseOffset),
2598 I.isVirtual() ? BaseDecl : NearestVBase, BaseOffsetFromNearestVBase,
2599 BaseDeclIsNonVirtualPrimaryBase, VTableClass, VBases, Vptrs);
2600 }
2601 }
2602
InitializeVTablePointers(const CXXRecordDecl * RD)2603 void CodeGenFunction::InitializeVTablePointers(const CXXRecordDecl *RD) {
2604 // Ignore classes without a vtable.
2605 if (!RD->isDynamicClass())
2606 return;
2607
2608 // Initialize the vtable pointers for this class and all of its bases.
2609 if (CGM.getCXXABI().doStructorsInitializeVPtrs(RD))
2610 for (const VPtr &Vptr : getVTablePointers(RD))
2611 InitializeVTablePointer(Vptr);
2612
2613 if (RD->getNumVBases())
2614 CGM.getCXXABI().initializeHiddenVirtualInheritanceMembers(*this, RD);
2615 }
2616
GetVTablePtr(Address This,llvm::Type * VTableTy,const CXXRecordDecl * RD)2617 llvm::Value *CodeGenFunction::GetVTablePtr(Address This,
2618 llvm::Type *VTableTy,
2619 const CXXRecordDecl *RD) {
2620 Address VTablePtrSrc = Builder.CreateElementBitCast(This, VTableTy);
2621 llvm::Instruction *VTable = Builder.CreateLoad(VTablePtrSrc, "vtable");
2622 TBAAAccessInfo TBAAInfo = CGM.getTBAAVTablePtrAccessInfo(VTableTy);
2623 CGM.DecorateInstructionWithTBAA(VTable, TBAAInfo);
2624
2625 if (CGM.getCodeGenOpts().OptimizationLevel > 0 &&
2626 CGM.getCodeGenOpts().StrictVTablePointers)
2627 CGM.DecorateInstructionWithInvariantGroup(VTable, RD);
2628
2629 return VTable;
2630 }
2631
2632 // If a class has a single non-virtual base and does not introduce or override
2633 // virtual member functions or fields, it will have the same layout as its base.
2634 // This function returns the least derived such class.
2635 //
2636 // Casting an instance of a base class to such a derived class is technically
2637 // undefined behavior, but it is a relatively common hack for introducing member
2638 // functions on class instances with specific properties (e.g. llvm::Operator)
2639 // that works under most compilers and should not have security implications, so
2640 // we allow it by default. It can be disabled with -fsanitize=cfi-cast-strict.
2641 static const CXXRecordDecl *
LeastDerivedClassWithSameLayout(const CXXRecordDecl * RD)2642 LeastDerivedClassWithSameLayout(const CXXRecordDecl *RD) {
2643 if (!RD->field_empty())
2644 return RD;
2645
2646 if (RD->getNumVBases() != 0)
2647 return RD;
2648
2649 if (RD->getNumBases() != 1)
2650 return RD;
2651
2652 for (const CXXMethodDecl *MD : RD->methods()) {
2653 if (MD->isVirtual()) {
2654 // Virtual member functions are only ok if they are implicit destructors
2655 // because the implicit destructor will have the same semantics as the
2656 // base class's destructor if no fields are added.
2657 if (isa<CXXDestructorDecl>(MD) && MD->isImplicit())
2658 continue;
2659 return RD;
2660 }
2661 }
2662
2663 return LeastDerivedClassWithSameLayout(
2664 RD->bases_begin()->getType()->getAsCXXRecordDecl());
2665 }
2666
EmitTypeMetadataCodeForVCall(const CXXRecordDecl * RD,llvm::Value * VTable,SourceLocation Loc)2667 void CodeGenFunction::EmitTypeMetadataCodeForVCall(const CXXRecordDecl *RD,
2668 llvm::Value *VTable,
2669 SourceLocation Loc) {
2670 if (SanOpts.has(SanitizerKind::CFIVCall))
2671 EmitVTablePtrCheckForCall(RD, VTable, CodeGenFunction::CFITCK_VCall, Loc);
2672 else if (CGM.getCodeGenOpts().WholeProgramVTables &&
2673 // Don't insert type test assumes if we are forcing public std
2674 // visibility.
2675 !CGM.HasLTOVisibilityPublicStd(RD)) {
2676 llvm::Metadata *MD =
2677 CGM.CreateMetadataIdentifierForType(QualType(RD->getTypeForDecl(), 0));
2678 llvm::Value *TypeId =
2679 llvm::MetadataAsValue::get(CGM.getLLVMContext(), MD);
2680
2681 llvm::Value *CastedVTable = Builder.CreateBitCast(VTable, Int8PtrTy);
2682 llvm::Value *TypeTest =
2683 Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::type_test),
2684 {CastedVTable, TypeId});
2685 Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::assume), TypeTest);
2686 }
2687 }
2688
EmitVTablePtrCheckForCall(const CXXRecordDecl * RD,llvm::Value * VTable,CFITypeCheckKind TCK,SourceLocation Loc)2689 void CodeGenFunction::EmitVTablePtrCheckForCall(const CXXRecordDecl *RD,
2690 llvm::Value *VTable,
2691 CFITypeCheckKind TCK,
2692 SourceLocation Loc) {
2693 if (!SanOpts.has(SanitizerKind::CFICastStrict))
2694 RD = LeastDerivedClassWithSameLayout(RD);
2695
2696 EmitVTablePtrCheck(RD, VTable, TCK, Loc);
2697 }
2698
EmitVTablePtrCheckForCast(QualType T,llvm::Value * Derived,bool MayBeNull,CFITypeCheckKind TCK,SourceLocation Loc)2699 void CodeGenFunction::EmitVTablePtrCheckForCast(QualType T,
2700 llvm::Value *Derived,
2701 bool MayBeNull,
2702 CFITypeCheckKind TCK,
2703 SourceLocation Loc) {
2704 if (!getLangOpts().CPlusPlus)
2705 return;
2706
2707 auto *ClassTy = T->getAs<RecordType>();
2708 if (!ClassTy)
2709 return;
2710
2711 const CXXRecordDecl *ClassDecl = cast<CXXRecordDecl>(ClassTy->getDecl());
2712
2713 if (!ClassDecl->isCompleteDefinition() || !ClassDecl->isDynamicClass())
2714 return;
2715
2716 if (!SanOpts.has(SanitizerKind::CFICastStrict))
2717 ClassDecl = LeastDerivedClassWithSameLayout(ClassDecl);
2718
2719 llvm::BasicBlock *ContBlock = nullptr;
2720
2721 if (MayBeNull) {
2722 llvm::Value *DerivedNotNull =
2723 Builder.CreateIsNotNull(Derived, "cast.nonnull");
2724
2725 llvm::BasicBlock *CheckBlock = createBasicBlock("cast.check");
2726 ContBlock = createBasicBlock("cast.cont");
2727
2728 Builder.CreateCondBr(DerivedNotNull, CheckBlock, ContBlock);
2729
2730 EmitBlock(CheckBlock);
2731 }
2732
2733 llvm::Value *VTable;
2734 std::tie(VTable, ClassDecl) = CGM.getCXXABI().LoadVTablePtr(
2735 *this, Address(Derived, getPointerAlign()), ClassDecl);
2736
2737 EmitVTablePtrCheck(ClassDecl, VTable, TCK, Loc);
2738
2739 if (MayBeNull) {
2740 Builder.CreateBr(ContBlock);
2741 EmitBlock(ContBlock);
2742 }
2743 }
2744
EmitVTablePtrCheck(const CXXRecordDecl * RD,llvm::Value * VTable,CFITypeCheckKind TCK,SourceLocation Loc)2745 void CodeGenFunction::EmitVTablePtrCheck(const CXXRecordDecl *RD,
2746 llvm::Value *VTable,
2747 CFITypeCheckKind TCK,
2748 SourceLocation Loc) {
2749 if (!CGM.getCodeGenOpts().SanitizeCfiCrossDso &&
2750 !CGM.HasHiddenLTOVisibility(RD))
2751 return;
2752
2753 SanitizerMask M;
2754 llvm::SanitizerStatKind SSK;
2755 switch (TCK) {
2756 case CFITCK_VCall:
2757 M = SanitizerKind::CFIVCall;
2758 SSK = llvm::SanStat_CFI_VCall;
2759 break;
2760 case CFITCK_NVCall:
2761 M = SanitizerKind::CFINVCall;
2762 SSK = llvm::SanStat_CFI_NVCall;
2763 break;
2764 case CFITCK_DerivedCast:
2765 M = SanitizerKind::CFIDerivedCast;
2766 SSK = llvm::SanStat_CFI_DerivedCast;
2767 break;
2768 case CFITCK_UnrelatedCast:
2769 M = SanitizerKind::CFIUnrelatedCast;
2770 SSK = llvm::SanStat_CFI_UnrelatedCast;
2771 break;
2772 case CFITCK_ICall:
2773 case CFITCK_NVMFCall:
2774 case CFITCK_VMFCall:
2775 llvm_unreachable("unexpected sanitizer kind");
2776 }
2777
2778 std::string TypeName = RD->getQualifiedNameAsString();
2779 if (getContext().getNoSanitizeList().containsType(M, TypeName))
2780 return;
2781
2782 SanitizerScope SanScope(this);
2783 EmitSanitizerStatReport(SSK);
2784
2785 llvm::Metadata *MD =
2786 CGM.CreateMetadataIdentifierForType(QualType(RD->getTypeForDecl(), 0));
2787 llvm::Value *TypeId = llvm::MetadataAsValue::get(getLLVMContext(), MD);
2788
2789 llvm::Value *CastedVTable = Builder.CreateBitCast(VTable, Int8PtrTy);
2790 llvm::Value *TypeTest = Builder.CreateCall(
2791 CGM.getIntrinsic(llvm::Intrinsic::type_test), {CastedVTable, TypeId});
2792
2793 llvm::Constant *StaticData[] = {
2794 llvm::ConstantInt::get(Int8Ty, TCK),
2795 EmitCheckSourceLocation(Loc),
2796 EmitCheckTypeDescriptor(QualType(RD->getTypeForDecl(), 0)),
2797 };
2798
2799 auto CrossDsoTypeId = CGM.CreateCrossDsoCfiTypeId(MD);
2800 if (CGM.getCodeGenOpts().SanitizeCfiCrossDso && CrossDsoTypeId) {
2801 EmitCfiSlowPathCheck(M, TypeTest, CrossDsoTypeId, CastedVTable, StaticData);
2802 return;
2803 }
2804
2805 if (CGM.getCodeGenOpts().SanitizeTrap.has(M)) {
2806 EmitTrapCheck(TypeTest, SanitizerHandler::CFICheckFail);
2807 return;
2808 }
2809
2810 llvm::Value *AllVtables = llvm::MetadataAsValue::get(
2811 CGM.getLLVMContext(),
2812 llvm::MDString::get(CGM.getLLVMContext(), "all-vtables"));
2813 llvm::Value *ValidVtable = Builder.CreateCall(
2814 CGM.getIntrinsic(llvm::Intrinsic::type_test), {CastedVTable, AllVtables});
2815 EmitCheck(std::make_pair(TypeTest, M), SanitizerHandler::CFICheckFail,
2816 StaticData, {CastedVTable, ValidVtable});
2817 }
2818
ShouldEmitVTableTypeCheckedLoad(const CXXRecordDecl * RD)2819 bool CodeGenFunction::ShouldEmitVTableTypeCheckedLoad(const CXXRecordDecl *RD) {
2820 if (!CGM.getCodeGenOpts().WholeProgramVTables ||
2821 !CGM.HasHiddenLTOVisibility(RD))
2822 return false;
2823
2824 if (CGM.getCodeGenOpts().VirtualFunctionElimination)
2825 return true;
2826
2827 if (!SanOpts.has(SanitizerKind::CFIVCall) ||
2828 !CGM.getCodeGenOpts().SanitizeTrap.has(SanitizerKind::CFIVCall))
2829 return false;
2830
2831 std::string TypeName = RD->getQualifiedNameAsString();
2832 return !getContext().getNoSanitizeList().containsType(SanitizerKind::CFIVCall,
2833 TypeName);
2834 }
2835
EmitVTableTypeCheckedLoad(const CXXRecordDecl * RD,llvm::Value * VTable,uint64_t VTableByteOffset)2836 llvm::Value *CodeGenFunction::EmitVTableTypeCheckedLoad(
2837 const CXXRecordDecl *RD, llvm::Value *VTable, uint64_t VTableByteOffset) {
2838 SanitizerScope SanScope(this);
2839
2840 EmitSanitizerStatReport(llvm::SanStat_CFI_VCall);
2841
2842 llvm::Metadata *MD =
2843 CGM.CreateMetadataIdentifierForType(QualType(RD->getTypeForDecl(), 0));
2844 llvm::Value *TypeId = llvm::MetadataAsValue::get(CGM.getLLVMContext(), MD);
2845
2846 llvm::Value *CastedVTable = Builder.CreateBitCast(VTable, Int8PtrTy);
2847 llvm::Value *CheckedLoad = Builder.CreateCall(
2848 CGM.getIntrinsic(llvm::Intrinsic::type_checked_load),
2849 {CastedVTable, llvm::ConstantInt::get(Int32Ty, VTableByteOffset),
2850 TypeId});
2851 llvm::Value *CheckResult = Builder.CreateExtractValue(CheckedLoad, 1);
2852
2853 std::string TypeName = RD->getQualifiedNameAsString();
2854 if (SanOpts.has(SanitizerKind::CFIVCall) &&
2855 !getContext().getNoSanitizeList().containsType(SanitizerKind::CFIVCall,
2856 TypeName)) {
2857 EmitCheck(std::make_pair(CheckResult, SanitizerKind::CFIVCall),
2858 SanitizerHandler::CFICheckFail, {}, {});
2859 }
2860
2861 return Builder.CreateBitCast(
2862 Builder.CreateExtractValue(CheckedLoad, 0),
2863 cast<llvm::PointerType>(VTable->getType())->getElementType());
2864 }
2865
EmitForwardingCallToLambda(const CXXMethodDecl * callOperator,CallArgList & callArgs)2866 void CodeGenFunction::EmitForwardingCallToLambda(
2867 const CXXMethodDecl *callOperator,
2868 CallArgList &callArgs) {
2869 // Get the address of the call operator.
2870 const CGFunctionInfo &calleeFnInfo =
2871 CGM.getTypes().arrangeCXXMethodDeclaration(callOperator);
2872 llvm::Constant *calleePtr =
2873 CGM.GetAddrOfFunction(GlobalDecl(callOperator),
2874 CGM.getTypes().GetFunctionType(calleeFnInfo));
2875
2876 // Prepare the return slot.
2877 const FunctionProtoType *FPT =
2878 callOperator->getType()->castAs<FunctionProtoType>();
2879 QualType resultType = FPT->getReturnType();
2880 ReturnValueSlot returnSlot;
2881 if (!resultType->isVoidType() &&
2882 calleeFnInfo.getReturnInfo().getKind() == ABIArgInfo::Indirect &&
2883 !hasScalarEvaluationKind(calleeFnInfo.getReturnType()))
2884 returnSlot =
2885 ReturnValueSlot(ReturnValue, resultType.isVolatileQualified(),
2886 /*IsUnused=*/false, /*IsExternallyDestructed=*/true);
2887
2888 // We don't need to separately arrange the call arguments because
2889 // the call can't be variadic anyway --- it's impossible to forward
2890 // variadic arguments.
2891
2892 // Now emit our call.
2893 auto callee = CGCallee::forDirect(calleePtr, GlobalDecl(callOperator));
2894 RValue RV = EmitCall(calleeFnInfo, callee, returnSlot, callArgs);
2895
2896 // If necessary, copy the returned value into the slot.
2897 if (!resultType->isVoidType() && returnSlot.isNull()) {
2898 if (getLangOpts().ObjCAutoRefCount && resultType->isObjCRetainableType()) {
2899 RV = RValue::get(EmitARCRetainAutoreleasedReturnValue(RV.getScalarVal()));
2900 }
2901 EmitReturnOfRValue(RV, resultType);
2902 } else
2903 EmitBranchThroughCleanup(ReturnBlock);
2904 }
2905
EmitLambdaBlockInvokeBody()2906 void CodeGenFunction::EmitLambdaBlockInvokeBody() {
2907 const BlockDecl *BD = BlockInfo->getBlockDecl();
2908 const VarDecl *variable = BD->capture_begin()->getVariable();
2909 const CXXRecordDecl *Lambda = variable->getType()->getAsCXXRecordDecl();
2910 const CXXMethodDecl *CallOp = Lambda->getLambdaCallOperator();
2911
2912 if (CallOp->isVariadic()) {
2913 // FIXME: Making this work correctly is nasty because it requires either
2914 // cloning the body of the call operator or making the call operator
2915 // forward.
2916 CGM.ErrorUnsupported(CurCodeDecl, "lambda conversion to variadic function");
2917 return;
2918 }
2919
2920 // Start building arguments for forwarding call
2921 CallArgList CallArgs;
2922
2923 QualType ThisType = getContext().getPointerType(getContext().getRecordType(Lambda));
2924 Address ThisPtr = GetAddrOfBlockDecl(variable);
2925 CallArgs.add(RValue::get(ThisPtr.getPointer()), ThisType);
2926
2927 // Add the rest of the parameters.
2928 for (auto param : BD->parameters())
2929 EmitDelegateCallArg(CallArgs, param, param->getBeginLoc());
2930
2931 assert(!Lambda->isGenericLambda() &&
2932 "generic lambda interconversion to block not implemented");
2933 EmitForwardingCallToLambda(CallOp, CallArgs);
2934 }
2935
EmitLambdaDelegatingInvokeBody(const CXXMethodDecl * MD)2936 void CodeGenFunction::EmitLambdaDelegatingInvokeBody(const CXXMethodDecl *MD) {
2937 const CXXRecordDecl *Lambda = MD->getParent();
2938
2939 // Start building arguments for forwarding call
2940 CallArgList CallArgs;
2941
2942 QualType ThisType = getContext().getPointerType(getContext().getRecordType(Lambda));
2943 llvm::Value *ThisPtr = llvm::UndefValue::get(getTypes().ConvertType(ThisType));
2944 CallArgs.add(RValue::get(ThisPtr), ThisType);
2945
2946 // Add the rest of the parameters.
2947 for (auto Param : MD->parameters())
2948 EmitDelegateCallArg(CallArgs, Param, Param->getBeginLoc());
2949
2950 const CXXMethodDecl *CallOp = Lambda->getLambdaCallOperator();
2951 // For a generic lambda, find the corresponding call operator specialization
2952 // to which the call to the static-invoker shall be forwarded.
2953 if (Lambda->isGenericLambda()) {
2954 assert(MD->isFunctionTemplateSpecialization());
2955 const TemplateArgumentList *TAL = MD->getTemplateSpecializationArgs();
2956 FunctionTemplateDecl *CallOpTemplate = CallOp->getDescribedFunctionTemplate();
2957 void *InsertPos = nullptr;
2958 FunctionDecl *CorrespondingCallOpSpecialization =
2959 CallOpTemplate->findSpecialization(TAL->asArray(), InsertPos);
2960 assert(CorrespondingCallOpSpecialization);
2961 CallOp = cast<CXXMethodDecl>(CorrespondingCallOpSpecialization);
2962 }
2963 EmitForwardingCallToLambda(CallOp, CallArgs);
2964 }
2965
EmitLambdaStaticInvokeBody(const CXXMethodDecl * MD)2966 void CodeGenFunction::EmitLambdaStaticInvokeBody(const CXXMethodDecl *MD) {
2967 if (MD->isVariadic()) {
2968 // FIXME: Making this work correctly is nasty because it requires either
2969 // cloning the body of the call operator or making the call operator forward.
2970 CGM.ErrorUnsupported(MD, "lambda conversion to variadic function");
2971 return;
2972 }
2973
2974 EmitLambdaDelegatingInvokeBody(MD);
2975 }
2976