1 //===--- MicrosoftCXXABI.cpp - Emit LLVM Code from ASTs for a Module ------===//
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 provides C++ code generation targeting the Microsoft Visual C++ ABI.
10 // The class in this file generates structures that follow the Microsoft
11 // Visual C++ ABI, which is actually not very well documented at all outside
12 // of Microsoft.
13 //
14 //===----------------------------------------------------------------------===//
15
16 #include "CGCXXABI.h"
17 #include "CGCleanup.h"
18 #include "CGVTables.h"
19 #include "CodeGenModule.h"
20 #include "CodeGenTypes.h"
21 #include "TargetInfo.h"
22 #include "clang/AST/Attr.h"
23 #include "clang/AST/CXXInheritance.h"
24 #include "clang/AST/Decl.h"
25 #include "clang/AST/DeclCXX.h"
26 #include "clang/AST/StmtCXX.h"
27 #include "clang/AST/VTableBuilder.h"
28 #include "clang/CodeGen/ConstantInitBuilder.h"
29 #include "llvm/ADT/StringExtras.h"
30 #include "llvm/ADT/StringSet.h"
31 #include "llvm/IR/Intrinsics.h"
32
33 using namespace clang;
34 using namespace CodeGen;
35
36 namespace {
37
38 /// Holds all the vbtable globals for a given class.
39 struct VBTableGlobals {
40 const VPtrInfoVector *VBTables;
41 SmallVector<llvm::GlobalVariable *, 2> Globals;
42 };
43
44 class MicrosoftCXXABI : public CGCXXABI {
45 public:
MicrosoftCXXABI(CodeGenModule & CGM)46 MicrosoftCXXABI(CodeGenModule &CGM)
47 : CGCXXABI(CGM), BaseClassDescriptorType(nullptr),
48 ClassHierarchyDescriptorType(nullptr),
49 CompleteObjectLocatorType(nullptr), CatchableTypeType(nullptr),
50 ThrowInfoType(nullptr) {}
51
52 bool HasThisReturn(GlobalDecl GD) const override;
53 bool hasMostDerivedReturn(GlobalDecl GD) const override;
54
55 bool classifyReturnType(CGFunctionInfo &FI) const override;
56
57 RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const override;
58
isSRetParameterAfterThis() const59 bool isSRetParameterAfterThis() const override { return true; }
60
isThisCompleteObject(GlobalDecl GD) const61 bool isThisCompleteObject(GlobalDecl GD) const override {
62 // The Microsoft ABI doesn't use separate complete-object vs.
63 // base-object variants of constructors, but it does of destructors.
64 if (isa<CXXDestructorDecl>(GD.getDecl())) {
65 switch (GD.getDtorType()) {
66 case Dtor_Complete:
67 case Dtor_Deleting:
68 return true;
69
70 case Dtor_Base:
71 return false;
72
73 case Dtor_Comdat: llvm_unreachable("emitting dtor comdat as function?");
74 }
75 llvm_unreachable("bad dtor kind");
76 }
77
78 // No other kinds.
79 return false;
80 }
81
getSrcArgforCopyCtor(const CXXConstructorDecl * CD,FunctionArgList & Args) const82 size_t getSrcArgforCopyCtor(const CXXConstructorDecl *CD,
83 FunctionArgList &Args) const override {
84 assert(Args.size() >= 2 &&
85 "expected the arglist to have at least two args!");
86 // The 'most_derived' parameter goes second if the ctor is variadic and
87 // has v-bases.
88 if (CD->getParent()->getNumVBases() > 0 &&
89 CD->getType()->castAs<FunctionProtoType>()->isVariadic())
90 return 2;
91 return 1;
92 }
93
getVBPtrOffsets(const CXXRecordDecl * RD)94 std::vector<CharUnits> getVBPtrOffsets(const CXXRecordDecl *RD) override {
95 std::vector<CharUnits> VBPtrOffsets;
96 const ASTContext &Context = getContext();
97 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
98
99 const VBTableGlobals &VBGlobals = enumerateVBTables(RD);
100 for (const std::unique_ptr<VPtrInfo> &VBT : *VBGlobals.VBTables) {
101 const ASTRecordLayout &SubobjectLayout =
102 Context.getASTRecordLayout(VBT->IntroducingObject);
103 CharUnits Offs = VBT->NonVirtualOffset;
104 Offs += SubobjectLayout.getVBPtrOffset();
105 if (VBT->getVBaseWithVPtr())
106 Offs += Layout.getVBaseClassOffset(VBT->getVBaseWithVPtr());
107 VBPtrOffsets.push_back(Offs);
108 }
109 llvm::array_pod_sort(VBPtrOffsets.begin(), VBPtrOffsets.end());
110 return VBPtrOffsets;
111 }
112
GetPureVirtualCallName()113 StringRef GetPureVirtualCallName() override { return "_purecall"; }
GetDeletedVirtualCallName()114 StringRef GetDeletedVirtualCallName() override { return "_purecall"; }
115
116 void emitVirtualObjectDelete(CodeGenFunction &CGF, const CXXDeleteExpr *DE,
117 Address Ptr, QualType ElementType,
118 const CXXDestructorDecl *Dtor) override;
119
120 void emitRethrow(CodeGenFunction &CGF, bool isNoReturn) override;
121 void emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) override;
122
123 void emitBeginCatch(CodeGenFunction &CGF, const CXXCatchStmt *C) override;
124
125 llvm::GlobalVariable *getMSCompleteObjectLocator(const CXXRecordDecl *RD,
126 const VPtrInfo &Info);
127
128 llvm::Constant *getAddrOfRTTIDescriptor(QualType Ty) override;
129 CatchTypeInfo
130 getAddrOfCXXCatchHandlerType(QualType Ty, QualType CatchHandlerType) override;
131
132 /// MSVC needs an extra flag to indicate a catchall.
getCatchAllTypeInfo()133 CatchTypeInfo getCatchAllTypeInfo() override {
134 return CatchTypeInfo{nullptr, 0x40};
135 }
136
137 bool shouldTypeidBeNullChecked(bool IsDeref, QualType SrcRecordTy) override;
138 void EmitBadTypeidCall(CodeGenFunction &CGF) override;
139 llvm::Value *EmitTypeid(CodeGenFunction &CGF, QualType SrcRecordTy,
140 Address ThisPtr,
141 llvm::Type *StdTypeInfoPtrTy) override;
142
143 bool shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,
144 QualType SrcRecordTy) override;
145
146 llvm::Value *EmitDynamicCastCall(CodeGenFunction &CGF, Address Value,
147 QualType SrcRecordTy, QualType DestTy,
148 QualType DestRecordTy,
149 llvm::BasicBlock *CastEnd) override;
150
151 llvm::Value *EmitDynamicCastToVoid(CodeGenFunction &CGF, Address Value,
152 QualType SrcRecordTy,
153 QualType DestTy) override;
154
155 bool EmitBadCastCall(CodeGenFunction &CGF) override;
canSpeculativelyEmitVTable(const CXXRecordDecl * RD) const156 bool canSpeculativelyEmitVTable(const CXXRecordDecl *RD) const override {
157 return false;
158 }
159
160 llvm::Value *
161 GetVirtualBaseClassOffset(CodeGenFunction &CGF, Address This,
162 const CXXRecordDecl *ClassDecl,
163 const CXXRecordDecl *BaseClassDecl) override;
164
165 llvm::BasicBlock *
166 EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
167 const CXXRecordDecl *RD) override;
168
169 llvm::BasicBlock *
170 EmitDtorCompleteObjectHandler(CodeGenFunction &CGF);
171
172 void initializeHiddenVirtualInheritanceMembers(CodeGenFunction &CGF,
173 const CXXRecordDecl *RD) override;
174
175 void EmitCXXConstructors(const CXXConstructorDecl *D) override;
176
177 // Background on MSVC destructors
178 // ==============================
179 //
180 // Both Itanium and MSVC ABIs have destructor variants. The variant names
181 // roughly correspond in the following way:
182 // Itanium Microsoft
183 // Base -> no name, just ~Class
184 // Complete -> vbase destructor
185 // Deleting -> scalar deleting destructor
186 // vector deleting destructor
187 //
188 // The base and complete destructors are the same as in Itanium, although the
189 // complete destructor does not accept a VTT parameter when there are virtual
190 // bases. A separate mechanism involving vtordisps is used to ensure that
191 // virtual methods of destroyed subobjects are not called.
192 //
193 // The deleting destructors accept an i32 bitfield as a second parameter. Bit
194 // 1 indicates if the memory should be deleted. Bit 2 indicates if the this
195 // pointer points to an array. The scalar deleting destructor assumes that
196 // bit 2 is zero, and therefore does not contain a loop.
197 //
198 // For virtual destructors, only one entry is reserved in the vftable, and it
199 // always points to the vector deleting destructor. The vector deleting
200 // destructor is the most general, so it can be used to destroy objects in
201 // place, delete single heap objects, or delete arrays.
202 //
203 // A TU defining a non-inline destructor is only guaranteed to emit a base
204 // destructor, and all of the other variants are emitted on an as-needed basis
205 // in COMDATs. Because a non-base destructor can be emitted in a TU that
206 // lacks a definition for the destructor, non-base destructors must always
207 // delegate to or alias the base destructor.
208
209 AddedStructorArgCounts
210 buildStructorSignature(GlobalDecl GD,
211 SmallVectorImpl<CanQualType> &ArgTys) override;
212
213 /// Non-base dtors should be emitted as delegating thunks in this ABI.
useThunkForDtorVariant(const CXXDestructorDecl * Dtor,CXXDtorType DT) const214 bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor,
215 CXXDtorType DT) const override {
216 return DT != Dtor_Base;
217 }
218
219 void setCXXDestructorDLLStorage(llvm::GlobalValue *GV,
220 const CXXDestructorDecl *Dtor,
221 CXXDtorType DT) const override;
222
223 llvm::GlobalValue::LinkageTypes
224 getCXXDestructorLinkage(GVALinkage Linkage, const CXXDestructorDecl *Dtor,
225 CXXDtorType DT) const override;
226
227 void EmitCXXDestructors(const CXXDestructorDecl *D) override;
228
229 const CXXRecordDecl *
getThisArgumentTypeForMethod(const CXXMethodDecl * MD)230 getThisArgumentTypeForMethod(const CXXMethodDecl *MD) override {
231 if (MD->isVirtual() && !isa<CXXDestructorDecl>(MD)) {
232 MethodVFTableLocation ML =
233 CGM.getMicrosoftVTableContext().getMethodVFTableLocation(MD);
234 // The vbases might be ordered differently in the final overrider object
235 // and the complete object, so the "this" argument may sometimes point to
236 // memory that has no particular type (e.g. past the complete object).
237 // In this case, we just use a generic pointer type.
238 // FIXME: might want to have a more precise type in the non-virtual
239 // multiple inheritance case.
240 if (ML.VBase || !ML.VFPtrOffset.isZero())
241 return nullptr;
242 }
243 return MD->getParent();
244 }
245
246 Address
247 adjustThisArgumentForVirtualFunctionCall(CodeGenFunction &CGF, GlobalDecl GD,
248 Address This,
249 bool VirtualCall) override;
250
251 void addImplicitStructorParams(CodeGenFunction &CGF, QualType &ResTy,
252 FunctionArgList &Params) override;
253
254 void EmitInstanceFunctionProlog(CodeGenFunction &CGF) override;
255
256 AddedStructorArgs getImplicitConstructorArgs(CodeGenFunction &CGF,
257 const CXXConstructorDecl *D,
258 CXXCtorType Type,
259 bool ForVirtualBase,
260 bool Delegating) override;
261
262 llvm::Value *getCXXDestructorImplicitParam(CodeGenFunction &CGF,
263 const CXXDestructorDecl *DD,
264 CXXDtorType Type,
265 bool ForVirtualBase,
266 bool Delegating) override;
267
268 void EmitDestructorCall(CodeGenFunction &CGF, const CXXDestructorDecl *DD,
269 CXXDtorType Type, bool ForVirtualBase,
270 bool Delegating, Address This,
271 QualType ThisTy) override;
272
273 void emitVTableTypeMetadata(const VPtrInfo &Info, const CXXRecordDecl *RD,
274 llvm::GlobalVariable *VTable);
275
276 void emitVTableDefinitions(CodeGenVTables &CGVT,
277 const CXXRecordDecl *RD) override;
278
279 bool isVirtualOffsetNeededForVTableField(CodeGenFunction &CGF,
280 CodeGenFunction::VPtr Vptr) override;
281
282 /// Don't initialize vptrs if dynamic class
283 /// is marked with with the 'novtable' attribute.
doStructorsInitializeVPtrs(const CXXRecordDecl * VTableClass)284 bool doStructorsInitializeVPtrs(const CXXRecordDecl *VTableClass) override {
285 return !VTableClass->hasAttr<MSNoVTableAttr>();
286 }
287
288 llvm::Constant *
289 getVTableAddressPoint(BaseSubobject Base,
290 const CXXRecordDecl *VTableClass) override;
291
292 llvm::Value *getVTableAddressPointInStructor(
293 CodeGenFunction &CGF, const CXXRecordDecl *VTableClass,
294 BaseSubobject Base, const CXXRecordDecl *NearestVBase) override;
295
296 llvm::Constant *
297 getVTableAddressPointForConstExpr(BaseSubobject Base,
298 const CXXRecordDecl *VTableClass) override;
299
300 llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD,
301 CharUnits VPtrOffset) override;
302
303 CGCallee getVirtualFunctionPointer(CodeGenFunction &CGF, GlobalDecl GD,
304 Address This, llvm::Type *Ty,
305 SourceLocation Loc) override;
306
307 llvm::Value *EmitVirtualDestructorCall(CodeGenFunction &CGF,
308 const CXXDestructorDecl *Dtor,
309 CXXDtorType DtorType, Address This,
310 DeleteOrMemberCallExpr E) override;
311
adjustCallArgsForDestructorThunk(CodeGenFunction & CGF,GlobalDecl GD,CallArgList & CallArgs)312 void adjustCallArgsForDestructorThunk(CodeGenFunction &CGF, GlobalDecl GD,
313 CallArgList &CallArgs) override {
314 assert(GD.getDtorType() == Dtor_Deleting &&
315 "Only deleting destructor thunks are available in this ABI");
316 CallArgs.add(RValue::get(getStructorImplicitParamValue(CGF)),
317 getContext().IntTy);
318 }
319
320 void emitVirtualInheritanceTables(const CXXRecordDecl *RD) override;
321
322 llvm::GlobalVariable *
323 getAddrOfVBTable(const VPtrInfo &VBT, const CXXRecordDecl *RD,
324 llvm::GlobalVariable::LinkageTypes Linkage);
325
326 llvm::GlobalVariable *
getAddrOfVirtualDisplacementMap(const CXXRecordDecl * SrcRD,const CXXRecordDecl * DstRD)327 getAddrOfVirtualDisplacementMap(const CXXRecordDecl *SrcRD,
328 const CXXRecordDecl *DstRD) {
329 SmallString<256> OutName;
330 llvm::raw_svector_ostream Out(OutName);
331 getMangleContext().mangleCXXVirtualDisplacementMap(SrcRD, DstRD, Out);
332 StringRef MangledName = OutName.str();
333
334 if (auto *VDispMap = CGM.getModule().getNamedGlobal(MangledName))
335 return VDispMap;
336
337 MicrosoftVTableContext &VTContext = CGM.getMicrosoftVTableContext();
338 unsigned NumEntries = 1 + SrcRD->getNumVBases();
339 SmallVector<llvm::Constant *, 4> Map(NumEntries,
340 llvm::UndefValue::get(CGM.IntTy));
341 Map[0] = llvm::ConstantInt::get(CGM.IntTy, 0);
342 bool AnyDifferent = false;
343 for (const auto &I : SrcRD->vbases()) {
344 const CXXRecordDecl *VBase = I.getType()->getAsCXXRecordDecl();
345 if (!DstRD->isVirtuallyDerivedFrom(VBase))
346 continue;
347
348 unsigned SrcVBIndex = VTContext.getVBTableIndex(SrcRD, VBase);
349 unsigned DstVBIndex = VTContext.getVBTableIndex(DstRD, VBase);
350 Map[SrcVBIndex] = llvm::ConstantInt::get(CGM.IntTy, DstVBIndex * 4);
351 AnyDifferent |= SrcVBIndex != DstVBIndex;
352 }
353 // This map would be useless, don't use it.
354 if (!AnyDifferent)
355 return nullptr;
356
357 llvm::ArrayType *VDispMapTy = llvm::ArrayType::get(CGM.IntTy, Map.size());
358 llvm::Constant *Init = llvm::ConstantArray::get(VDispMapTy, Map);
359 llvm::GlobalValue::LinkageTypes Linkage =
360 SrcRD->isExternallyVisible() && DstRD->isExternallyVisible()
361 ? llvm::GlobalValue::LinkOnceODRLinkage
362 : llvm::GlobalValue::InternalLinkage;
363 auto *VDispMap = new llvm::GlobalVariable(
364 CGM.getModule(), VDispMapTy, /*isConstant=*/true, Linkage,
365 /*Initializer=*/Init, MangledName);
366 return VDispMap;
367 }
368
369 void emitVBTableDefinition(const VPtrInfo &VBT, const CXXRecordDecl *RD,
370 llvm::GlobalVariable *GV) const;
371
setThunkLinkage(llvm::Function * Thunk,bool ForVTable,GlobalDecl GD,bool ReturnAdjustment)372 void setThunkLinkage(llvm::Function *Thunk, bool ForVTable,
373 GlobalDecl GD, bool ReturnAdjustment) override {
374 GVALinkage Linkage =
375 getContext().GetGVALinkageForFunction(cast<FunctionDecl>(GD.getDecl()));
376
377 if (Linkage == GVA_Internal)
378 Thunk->setLinkage(llvm::GlobalValue::InternalLinkage);
379 else if (ReturnAdjustment)
380 Thunk->setLinkage(llvm::GlobalValue::WeakODRLinkage);
381 else
382 Thunk->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage);
383 }
384
exportThunk()385 bool exportThunk() override { return false; }
386
387 llvm::Value *performThisAdjustment(CodeGenFunction &CGF, Address This,
388 const ThisAdjustment &TA) override;
389
390 llvm::Value *performReturnAdjustment(CodeGenFunction &CGF, Address Ret,
391 const ReturnAdjustment &RA) override;
392
393 void EmitThreadLocalInitFuncs(
394 CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals,
395 ArrayRef<llvm::Function *> CXXThreadLocalInits,
396 ArrayRef<const VarDecl *> CXXThreadLocalInitVars) override;
397
usesThreadWrapperFunction(const VarDecl * VD) const398 bool usesThreadWrapperFunction(const VarDecl *VD) const override {
399 return false;
400 }
401 LValue EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF, const VarDecl *VD,
402 QualType LValType) override;
403
404 void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
405 llvm::GlobalVariable *DeclPtr,
406 bool PerformInit) override;
407 void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,
408 llvm::FunctionCallee Dtor,
409 llvm::Constant *Addr) override;
410
411 // ==== Notes on array cookies =========
412 //
413 // MSVC seems to only use cookies when the class has a destructor; a
414 // two-argument usual array deallocation function isn't sufficient.
415 //
416 // For example, this code prints "100" and "1":
417 // struct A {
418 // char x;
419 // void *operator new[](size_t sz) {
420 // printf("%u\n", sz);
421 // return malloc(sz);
422 // }
423 // void operator delete[](void *p, size_t sz) {
424 // printf("%u\n", sz);
425 // free(p);
426 // }
427 // };
428 // int main() {
429 // A *p = new A[100];
430 // delete[] p;
431 // }
432 // Whereas it prints "104" and "104" if you give A a destructor.
433
434 bool requiresArrayCookie(const CXXDeleteExpr *expr,
435 QualType elementType) override;
436 bool requiresArrayCookie(const CXXNewExpr *expr) override;
437 CharUnits getArrayCookieSizeImpl(QualType type) override;
438 Address InitializeArrayCookie(CodeGenFunction &CGF,
439 Address NewPtr,
440 llvm::Value *NumElements,
441 const CXXNewExpr *expr,
442 QualType ElementType) override;
443 llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF,
444 Address allocPtr,
445 CharUnits cookieSize) override;
446
447 friend struct MSRTTIBuilder;
448
isImageRelative() const449 bool isImageRelative() const {
450 return CGM.getTarget().getPointerWidth(/*AddrSpace=*/0) == 64;
451 }
452
453 // 5 routines for constructing the llvm types for MS RTTI structs.
getTypeDescriptorType(StringRef TypeInfoString)454 llvm::StructType *getTypeDescriptorType(StringRef TypeInfoString) {
455 llvm::SmallString<32> TDTypeName("rtti.TypeDescriptor");
456 TDTypeName += llvm::utostr(TypeInfoString.size());
457 llvm::StructType *&TypeDescriptorType =
458 TypeDescriptorTypeMap[TypeInfoString.size()];
459 if (TypeDescriptorType)
460 return TypeDescriptorType;
461 llvm::Type *FieldTypes[] = {
462 CGM.Int8PtrPtrTy,
463 CGM.Int8PtrTy,
464 llvm::ArrayType::get(CGM.Int8Ty, TypeInfoString.size() + 1)};
465 TypeDescriptorType =
466 llvm::StructType::create(CGM.getLLVMContext(), FieldTypes, TDTypeName);
467 return TypeDescriptorType;
468 }
469
getImageRelativeType(llvm::Type * PtrType)470 llvm::Type *getImageRelativeType(llvm::Type *PtrType) {
471 if (!isImageRelative())
472 return PtrType;
473 return CGM.IntTy;
474 }
475
getBaseClassDescriptorType()476 llvm::StructType *getBaseClassDescriptorType() {
477 if (BaseClassDescriptorType)
478 return BaseClassDescriptorType;
479 llvm::Type *FieldTypes[] = {
480 getImageRelativeType(CGM.Int8PtrTy),
481 CGM.IntTy,
482 CGM.IntTy,
483 CGM.IntTy,
484 CGM.IntTy,
485 CGM.IntTy,
486 getImageRelativeType(getClassHierarchyDescriptorType()->getPointerTo()),
487 };
488 BaseClassDescriptorType = llvm::StructType::create(
489 CGM.getLLVMContext(), FieldTypes, "rtti.BaseClassDescriptor");
490 return BaseClassDescriptorType;
491 }
492
getClassHierarchyDescriptorType()493 llvm::StructType *getClassHierarchyDescriptorType() {
494 if (ClassHierarchyDescriptorType)
495 return ClassHierarchyDescriptorType;
496 // Forward-declare RTTIClassHierarchyDescriptor to break a cycle.
497 ClassHierarchyDescriptorType = llvm::StructType::create(
498 CGM.getLLVMContext(), "rtti.ClassHierarchyDescriptor");
499 llvm::Type *FieldTypes[] = {
500 CGM.IntTy,
501 CGM.IntTy,
502 CGM.IntTy,
503 getImageRelativeType(
504 getBaseClassDescriptorType()->getPointerTo()->getPointerTo()),
505 };
506 ClassHierarchyDescriptorType->setBody(FieldTypes);
507 return ClassHierarchyDescriptorType;
508 }
509
getCompleteObjectLocatorType()510 llvm::StructType *getCompleteObjectLocatorType() {
511 if (CompleteObjectLocatorType)
512 return CompleteObjectLocatorType;
513 CompleteObjectLocatorType = llvm::StructType::create(
514 CGM.getLLVMContext(), "rtti.CompleteObjectLocator");
515 llvm::Type *FieldTypes[] = {
516 CGM.IntTy,
517 CGM.IntTy,
518 CGM.IntTy,
519 getImageRelativeType(CGM.Int8PtrTy),
520 getImageRelativeType(getClassHierarchyDescriptorType()->getPointerTo()),
521 getImageRelativeType(CompleteObjectLocatorType),
522 };
523 llvm::ArrayRef<llvm::Type *> FieldTypesRef(FieldTypes);
524 if (!isImageRelative())
525 FieldTypesRef = FieldTypesRef.drop_back();
526 CompleteObjectLocatorType->setBody(FieldTypesRef);
527 return CompleteObjectLocatorType;
528 }
529
getImageBase()530 llvm::GlobalVariable *getImageBase() {
531 StringRef Name = "__ImageBase";
532 if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(Name))
533 return GV;
534
535 auto *GV = new llvm::GlobalVariable(CGM.getModule(), CGM.Int8Ty,
536 /*isConstant=*/true,
537 llvm::GlobalValue::ExternalLinkage,
538 /*Initializer=*/nullptr, Name);
539 CGM.setDSOLocal(GV);
540 return GV;
541 }
542
getImageRelativeConstant(llvm::Constant * PtrVal)543 llvm::Constant *getImageRelativeConstant(llvm::Constant *PtrVal) {
544 if (!isImageRelative())
545 return PtrVal;
546
547 if (PtrVal->isNullValue())
548 return llvm::Constant::getNullValue(CGM.IntTy);
549
550 llvm::Constant *ImageBaseAsInt =
551 llvm::ConstantExpr::getPtrToInt(getImageBase(), CGM.IntPtrTy);
552 llvm::Constant *PtrValAsInt =
553 llvm::ConstantExpr::getPtrToInt(PtrVal, CGM.IntPtrTy);
554 llvm::Constant *Diff =
555 llvm::ConstantExpr::getSub(PtrValAsInt, ImageBaseAsInt,
556 /*HasNUW=*/true, /*HasNSW=*/true);
557 return llvm::ConstantExpr::getTrunc(Diff, CGM.IntTy);
558 }
559
560 private:
getMangleContext()561 MicrosoftMangleContext &getMangleContext() {
562 return cast<MicrosoftMangleContext>(CodeGen::CGCXXABI::getMangleContext());
563 }
564
getZeroInt()565 llvm::Constant *getZeroInt() {
566 return llvm::ConstantInt::get(CGM.IntTy, 0);
567 }
568
getAllOnesInt()569 llvm::Constant *getAllOnesInt() {
570 return llvm::Constant::getAllOnesValue(CGM.IntTy);
571 }
572
573 CharUnits getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) override;
574
575 void
576 GetNullMemberPointerFields(const MemberPointerType *MPT,
577 llvm::SmallVectorImpl<llvm::Constant *> &fields);
578
579 /// Shared code for virtual base adjustment. Returns the offset from
580 /// the vbptr to the virtual base. Optionally returns the address of the
581 /// vbptr itself.
582 llvm::Value *GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,
583 Address Base,
584 llvm::Value *VBPtrOffset,
585 llvm::Value *VBTableOffset,
586 llvm::Value **VBPtr = nullptr);
587
GetVBaseOffsetFromVBPtr(CodeGenFunction & CGF,Address Base,int32_t VBPtrOffset,int32_t VBTableOffset,llvm::Value ** VBPtr=nullptr)588 llvm::Value *GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,
589 Address Base,
590 int32_t VBPtrOffset,
591 int32_t VBTableOffset,
592 llvm::Value **VBPtr = nullptr) {
593 assert(VBTableOffset % 4 == 0 && "should be byte offset into table of i32s");
594 llvm::Value *VBPOffset = llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset),
595 *VBTOffset = llvm::ConstantInt::get(CGM.IntTy, VBTableOffset);
596 return GetVBaseOffsetFromVBPtr(CGF, Base, VBPOffset, VBTOffset, VBPtr);
597 }
598
599 std::tuple<Address, llvm::Value *, const CXXRecordDecl *>
600 performBaseAdjustment(CodeGenFunction &CGF, Address Value,
601 QualType SrcRecordTy);
602
603 /// Performs a full virtual base adjustment. Used to dereference
604 /// pointers to members of virtual bases.
605 llvm::Value *AdjustVirtualBase(CodeGenFunction &CGF, const Expr *E,
606 const CXXRecordDecl *RD, Address Base,
607 llvm::Value *VirtualBaseAdjustmentOffset,
608 llvm::Value *VBPtrOffset /* optional */);
609
610 /// Emits a full member pointer with the fields common to data and
611 /// function member pointers.
612 llvm::Constant *EmitFullMemberPointer(llvm::Constant *FirstField,
613 bool IsMemberFunction,
614 const CXXRecordDecl *RD,
615 CharUnits NonVirtualBaseAdjustment,
616 unsigned VBTableIndex);
617
618 bool MemberPointerConstantIsNull(const MemberPointerType *MPT,
619 llvm::Constant *MP);
620
621 /// - Initialize all vbptrs of 'this' with RD as the complete type.
622 void EmitVBPtrStores(CodeGenFunction &CGF, const CXXRecordDecl *RD);
623
624 /// Caching wrapper around VBTableBuilder::enumerateVBTables().
625 const VBTableGlobals &enumerateVBTables(const CXXRecordDecl *RD);
626
627 /// Generate a thunk for calling a virtual member function MD.
628 llvm::Function *EmitVirtualMemPtrThunk(const CXXMethodDecl *MD,
629 const MethodVFTableLocation &ML);
630
631 llvm::Constant *EmitMemberDataPointer(const CXXRecordDecl *RD,
632 CharUnits offset);
633
634 public:
635 llvm::Type *ConvertMemberPointerType(const MemberPointerType *MPT) override;
636
637 bool isZeroInitializable(const MemberPointerType *MPT) override;
638
isMemberPointerConvertible(const MemberPointerType * MPT) const639 bool isMemberPointerConvertible(const MemberPointerType *MPT) const override {
640 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
641 return RD->hasAttr<MSInheritanceAttr>();
642 }
643
644 llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT) override;
645
646 llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,
647 CharUnits offset) override;
648 llvm::Constant *EmitMemberFunctionPointer(const CXXMethodDecl *MD) override;
649 llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT) override;
650
651 llvm::Value *EmitMemberPointerComparison(CodeGenFunction &CGF,
652 llvm::Value *L,
653 llvm::Value *R,
654 const MemberPointerType *MPT,
655 bool Inequality) override;
656
657 llvm::Value *EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
658 llvm::Value *MemPtr,
659 const MemberPointerType *MPT) override;
660
661 llvm::Value *
662 EmitMemberDataPointerAddress(CodeGenFunction &CGF, const Expr *E,
663 Address Base, llvm::Value *MemPtr,
664 const MemberPointerType *MPT) override;
665
666 llvm::Value *EmitNonNullMemberPointerConversion(
667 const MemberPointerType *SrcTy, const MemberPointerType *DstTy,
668 CastKind CK, CastExpr::path_const_iterator PathBegin,
669 CastExpr::path_const_iterator PathEnd, llvm::Value *Src,
670 CGBuilderTy &Builder);
671
672 llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,
673 const CastExpr *E,
674 llvm::Value *Src) override;
675
676 llvm::Constant *EmitMemberPointerConversion(const CastExpr *E,
677 llvm::Constant *Src) override;
678
679 llvm::Constant *EmitMemberPointerConversion(
680 const MemberPointerType *SrcTy, const MemberPointerType *DstTy,
681 CastKind CK, CastExpr::path_const_iterator PathBegin,
682 CastExpr::path_const_iterator PathEnd, llvm::Constant *Src);
683
684 CGCallee
685 EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, const Expr *E,
686 Address This, llvm::Value *&ThisPtrForCall,
687 llvm::Value *MemPtr,
688 const MemberPointerType *MPT) override;
689
690 void emitCXXStructor(GlobalDecl GD) override;
691
getCatchableTypeType()692 llvm::StructType *getCatchableTypeType() {
693 if (CatchableTypeType)
694 return CatchableTypeType;
695 llvm::Type *FieldTypes[] = {
696 CGM.IntTy, // Flags
697 getImageRelativeType(CGM.Int8PtrTy), // TypeDescriptor
698 CGM.IntTy, // NonVirtualAdjustment
699 CGM.IntTy, // OffsetToVBPtr
700 CGM.IntTy, // VBTableIndex
701 CGM.IntTy, // Size
702 getImageRelativeType(CGM.Int8PtrTy) // CopyCtor
703 };
704 CatchableTypeType = llvm::StructType::create(
705 CGM.getLLVMContext(), FieldTypes, "eh.CatchableType");
706 return CatchableTypeType;
707 }
708
getCatchableTypeArrayType(uint32_t NumEntries)709 llvm::StructType *getCatchableTypeArrayType(uint32_t NumEntries) {
710 llvm::StructType *&CatchableTypeArrayType =
711 CatchableTypeArrayTypeMap[NumEntries];
712 if (CatchableTypeArrayType)
713 return CatchableTypeArrayType;
714
715 llvm::SmallString<23> CTATypeName("eh.CatchableTypeArray.");
716 CTATypeName += llvm::utostr(NumEntries);
717 llvm::Type *CTType =
718 getImageRelativeType(getCatchableTypeType()->getPointerTo());
719 llvm::Type *FieldTypes[] = {
720 CGM.IntTy, // NumEntries
721 llvm::ArrayType::get(CTType, NumEntries) // CatchableTypes
722 };
723 CatchableTypeArrayType =
724 llvm::StructType::create(CGM.getLLVMContext(), FieldTypes, CTATypeName);
725 return CatchableTypeArrayType;
726 }
727
getThrowInfoType()728 llvm::StructType *getThrowInfoType() {
729 if (ThrowInfoType)
730 return ThrowInfoType;
731 llvm::Type *FieldTypes[] = {
732 CGM.IntTy, // Flags
733 getImageRelativeType(CGM.Int8PtrTy), // CleanupFn
734 getImageRelativeType(CGM.Int8PtrTy), // ForwardCompat
735 getImageRelativeType(CGM.Int8PtrTy) // CatchableTypeArray
736 };
737 ThrowInfoType = llvm::StructType::create(CGM.getLLVMContext(), FieldTypes,
738 "eh.ThrowInfo");
739 return ThrowInfoType;
740 }
741
getThrowFn()742 llvm::FunctionCallee getThrowFn() {
743 // _CxxThrowException is passed an exception object and a ThrowInfo object
744 // which describes the exception.
745 llvm::Type *Args[] = {CGM.Int8PtrTy, getThrowInfoType()->getPointerTo()};
746 llvm::FunctionType *FTy =
747 llvm::FunctionType::get(CGM.VoidTy, Args, /*isVarArg=*/false);
748 llvm::FunctionCallee Throw =
749 CGM.CreateRuntimeFunction(FTy, "_CxxThrowException");
750 // _CxxThrowException is stdcall on 32-bit x86 platforms.
751 if (CGM.getTarget().getTriple().getArch() == llvm::Triple::x86) {
752 if (auto *Fn = dyn_cast<llvm::Function>(Throw.getCallee()))
753 Fn->setCallingConv(llvm::CallingConv::X86_StdCall);
754 }
755 return Throw;
756 }
757
758 llvm::Function *getAddrOfCXXCtorClosure(const CXXConstructorDecl *CD,
759 CXXCtorType CT);
760
761 llvm::Constant *getCatchableType(QualType T,
762 uint32_t NVOffset = 0,
763 int32_t VBPtrOffset = -1,
764 uint32_t VBIndex = 0);
765
766 llvm::GlobalVariable *getCatchableTypeArray(QualType T);
767
768 llvm::GlobalVariable *getThrowInfo(QualType T) override;
769
770 std::pair<llvm::Value *, const CXXRecordDecl *>
771 LoadVTablePtr(CodeGenFunction &CGF, Address This,
772 const CXXRecordDecl *RD) override;
773
774 virtual bool
775 isPermittedToBeHomogeneousAggregate(const CXXRecordDecl *RD) const override;
776
777 private:
778 typedef std::pair<const CXXRecordDecl *, CharUnits> VFTableIdTy;
779 typedef llvm::DenseMap<VFTableIdTy, llvm::GlobalVariable *> VTablesMapTy;
780 typedef llvm::DenseMap<VFTableIdTy, llvm::GlobalValue *> VFTablesMapTy;
781 /// All the vftables that have been referenced.
782 VFTablesMapTy VFTablesMap;
783 VTablesMapTy VTablesMap;
784
785 /// This set holds the record decls we've deferred vtable emission for.
786 llvm::SmallPtrSet<const CXXRecordDecl *, 4> DeferredVFTables;
787
788
789 /// All the vbtables which have been referenced.
790 llvm::DenseMap<const CXXRecordDecl *, VBTableGlobals> VBTablesMap;
791
792 /// Info on the global variable used to guard initialization of static locals.
793 /// The BitIndex field is only used for externally invisible declarations.
794 struct GuardInfo {
GuardInfo__anon400b770b0111::MicrosoftCXXABI::GuardInfo795 GuardInfo() : Guard(nullptr), BitIndex(0) {}
796 llvm::GlobalVariable *Guard;
797 unsigned BitIndex;
798 };
799
800 /// Map from DeclContext to the current guard variable. We assume that the
801 /// AST is visited in source code order.
802 llvm::DenseMap<const DeclContext *, GuardInfo> GuardVariableMap;
803 llvm::DenseMap<const DeclContext *, GuardInfo> ThreadLocalGuardVariableMap;
804 llvm::DenseMap<const DeclContext *, unsigned> ThreadSafeGuardNumMap;
805
806 llvm::DenseMap<size_t, llvm::StructType *> TypeDescriptorTypeMap;
807 llvm::StructType *BaseClassDescriptorType;
808 llvm::StructType *ClassHierarchyDescriptorType;
809 llvm::StructType *CompleteObjectLocatorType;
810
811 llvm::DenseMap<QualType, llvm::GlobalVariable *> CatchableTypeArrays;
812
813 llvm::StructType *CatchableTypeType;
814 llvm::DenseMap<uint32_t, llvm::StructType *> CatchableTypeArrayTypeMap;
815 llvm::StructType *ThrowInfoType;
816 };
817
818 }
819
820 CGCXXABI::RecordArgABI
getRecordArgABI(const CXXRecordDecl * RD) const821 MicrosoftCXXABI::getRecordArgABI(const CXXRecordDecl *RD) const {
822 // Use the default C calling convention rules for things that can be passed in
823 // registers, i.e. non-trivially copyable records or records marked with
824 // [[trivial_abi]].
825 if (RD->canPassInRegisters())
826 return RAA_Default;
827
828 switch (CGM.getTarget().getTriple().getArch()) {
829 default:
830 // FIXME: Implement for other architectures.
831 return RAA_Indirect;
832
833 case llvm::Triple::thumb:
834 // Pass things indirectly for now because it is simple.
835 // FIXME: This is incompatible with MSVC for arguments with a dtor and no
836 // copy ctor.
837 return RAA_Indirect;
838
839 case llvm::Triple::x86: {
840 // If the argument has *required* alignment greater than four bytes, pass
841 // it indirectly. Prior to MSVC version 19.14, passing overaligned
842 // arguments was not supported and resulted in a compiler error. In 19.14
843 // and later versions, such arguments are now passed indirectly.
844 TypeInfo Info = getContext().getTypeInfo(RD->getTypeForDecl());
845 if (Info.AlignIsRequired && Info.Align > 4)
846 return RAA_Indirect;
847
848 // If C++ prohibits us from making a copy, construct the arguments directly
849 // into argument memory.
850 return RAA_DirectInMemory;
851 }
852
853 case llvm::Triple::x86_64:
854 case llvm::Triple::aarch64:
855 return RAA_Indirect;
856 }
857
858 llvm_unreachable("invalid enum");
859 }
860
emitVirtualObjectDelete(CodeGenFunction & CGF,const CXXDeleteExpr * DE,Address Ptr,QualType ElementType,const CXXDestructorDecl * Dtor)861 void MicrosoftCXXABI::emitVirtualObjectDelete(CodeGenFunction &CGF,
862 const CXXDeleteExpr *DE,
863 Address Ptr,
864 QualType ElementType,
865 const CXXDestructorDecl *Dtor) {
866 // FIXME: Provide a source location here even though there's no
867 // CXXMemberCallExpr for dtor call.
868 bool UseGlobalDelete = DE->isGlobalDelete();
869 CXXDtorType DtorType = UseGlobalDelete ? Dtor_Complete : Dtor_Deleting;
870 llvm::Value *MDThis = EmitVirtualDestructorCall(CGF, Dtor, DtorType, Ptr, DE);
871 if (UseGlobalDelete)
872 CGF.EmitDeleteCall(DE->getOperatorDelete(), MDThis, ElementType);
873 }
874
emitRethrow(CodeGenFunction & CGF,bool isNoReturn)875 void MicrosoftCXXABI::emitRethrow(CodeGenFunction &CGF, bool isNoReturn) {
876 llvm::Value *Args[] = {
877 llvm::ConstantPointerNull::get(CGM.Int8PtrTy),
878 llvm::ConstantPointerNull::get(getThrowInfoType()->getPointerTo())};
879 llvm::FunctionCallee Fn = getThrowFn();
880 if (isNoReturn)
881 CGF.EmitNoreturnRuntimeCallOrInvoke(Fn, Args);
882 else
883 CGF.EmitRuntimeCallOrInvoke(Fn, Args);
884 }
885
emitBeginCatch(CodeGenFunction & CGF,const CXXCatchStmt * S)886 void MicrosoftCXXABI::emitBeginCatch(CodeGenFunction &CGF,
887 const CXXCatchStmt *S) {
888 // In the MS ABI, the runtime handles the copy, and the catch handler is
889 // responsible for destruction.
890 VarDecl *CatchParam = S->getExceptionDecl();
891 llvm::BasicBlock *CatchPadBB = CGF.Builder.GetInsertBlock();
892 llvm::CatchPadInst *CPI =
893 cast<llvm::CatchPadInst>(CatchPadBB->getFirstNonPHI());
894 CGF.CurrentFuncletPad = CPI;
895
896 // If this is a catch-all or the catch parameter is unnamed, we don't need to
897 // emit an alloca to the object.
898 if (!CatchParam || !CatchParam->getDeclName()) {
899 CGF.EHStack.pushCleanup<CatchRetScope>(NormalCleanup, CPI);
900 return;
901 }
902
903 CodeGenFunction::AutoVarEmission var = CGF.EmitAutoVarAlloca(*CatchParam);
904 CPI->setArgOperand(2, var.getObjectAddress(CGF).getPointer());
905 CGF.EHStack.pushCleanup<CatchRetScope>(NormalCleanup, CPI);
906 CGF.EmitAutoVarCleanups(var);
907 }
908
909 /// We need to perform a generic polymorphic operation (like a typeid
910 /// or a cast), which requires an object with a vfptr. Adjust the
911 /// address to point to an object with a vfptr.
912 std::tuple<Address, llvm::Value *, const CXXRecordDecl *>
performBaseAdjustment(CodeGenFunction & CGF,Address Value,QualType SrcRecordTy)913 MicrosoftCXXABI::performBaseAdjustment(CodeGenFunction &CGF, Address Value,
914 QualType SrcRecordTy) {
915 Value = CGF.Builder.CreateBitCast(Value, CGF.Int8PtrTy);
916 const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();
917 const ASTContext &Context = getContext();
918
919 // If the class itself has a vfptr, great. This check implicitly
920 // covers non-virtual base subobjects: a class with its own virtual
921 // functions would be a candidate to be a primary base.
922 if (Context.getASTRecordLayout(SrcDecl).hasExtendableVFPtr())
923 return std::make_tuple(Value, llvm::ConstantInt::get(CGF.Int32Ty, 0),
924 SrcDecl);
925
926 // Okay, one of the vbases must have a vfptr, or else this isn't
927 // actually a polymorphic class.
928 const CXXRecordDecl *PolymorphicBase = nullptr;
929 for (auto &Base : SrcDecl->vbases()) {
930 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
931 if (Context.getASTRecordLayout(BaseDecl).hasExtendableVFPtr()) {
932 PolymorphicBase = BaseDecl;
933 break;
934 }
935 }
936 assert(PolymorphicBase && "polymorphic class has no apparent vfptr?");
937
938 llvm::Value *Offset =
939 GetVirtualBaseClassOffset(CGF, Value, SrcDecl, PolymorphicBase);
940 llvm::Value *Ptr = CGF.Builder.CreateInBoundsGEP(Value.getPointer(), Offset);
941 CharUnits VBaseAlign =
942 CGF.CGM.getVBaseAlignment(Value.getAlignment(), SrcDecl, PolymorphicBase);
943 return std::make_tuple(Address(Ptr, VBaseAlign), Offset, PolymorphicBase);
944 }
945
shouldTypeidBeNullChecked(bool IsDeref,QualType SrcRecordTy)946 bool MicrosoftCXXABI::shouldTypeidBeNullChecked(bool IsDeref,
947 QualType SrcRecordTy) {
948 const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();
949 return IsDeref &&
950 !getContext().getASTRecordLayout(SrcDecl).hasExtendableVFPtr();
951 }
952
emitRTtypeidCall(CodeGenFunction & CGF,llvm::Value * Argument)953 static llvm::CallBase *emitRTtypeidCall(CodeGenFunction &CGF,
954 llvm::Value *Argument) {
955 llvm::Type *ArgTypes[] = {CGF.Int8PtrTy};
956 llvm::FunctionType *FTy =
957 llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false);
958 llvm::Value *Args[] = {Argument};
959 llvm::FunctionCallee Fn = CGF.CGM.CreateRuntimeFunction(FTy, "__RTtypeid");
960 return CGF.EmitRuntimeCallOrInvoke(Fn, Args);
961 }
962
EmitBadTypeidCall(CodeGenFunction & CGF)963 void MicrosoftCXXABI::EmitBadTypeidCall(CodeGenFunction &CGF) {
964 llvm::CallBase *Call =
965 emitRTtypeidCall(CGF, llvm::Constant::getNullValue(CGM.VoidPtrTy));
966 Call->setDoesNotReturn();
967 CGF.Builder.CreateUnreachable();
968 }
969
EmitTypeid(CodeGenFunction & CGF,QualType SrcRecordTy,Address ThisPtr,llvm::Type * StdTypeInfoPtrTy)970 llvm::Value *MicrosoftCXXABI::EmitTypeid(CodeGenFunction &CGF,
971 QualType SrcRecordTy,
972 Address ThisPtr,
973 llvm::Type *StdTypeInfoPtrTy) {
974 std::tie(ThisPtr, std::ignore, std::ignore) =
975 performBaseAdjustment(CGF, ThisPtr, SrcRecordTy);
976 llvm::CallBase *Typeid = emitRTtypeidCall(CGF, ThisPtr.getPointer());
977 return CGF.Builder.CreateBitCast(Typeid, StdTypeInfoPtrTy);
978 }
979
shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,QualType SrcRecordTy)980 bool MicrosoftCXXABI::shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,
981 QualType SrcRecordTy) {
982 const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();
983 return SrcIsPtr &&
984 !getContext().getASTRecordLayout(SrcDecl).hasExtendableVFPtr();
985 }
986
EmitDynamicCastCall(CodeGenFunction & CGF,Address This,QualType SrcRecordTy,QualType DestTy,QualType DestRecordTy,llvm::BasicBlock * CastEnd)987 llvm::Value *MicrosoftCXXABI::EmitDynamicCastCall(
988 CodeGenFunction &CGF, Address This, QualType SrcRecordTy,
989 QualType DestTy, QualType DestRecordTy, llvm::BasicBlock *CastEnd) {
990 llvm::Type *DestLTy = CGF.ConvertType(DestTy);
991
992 llvm::Value *SrcRTTI =
993 CGF.CGM.GetAddrOfRTTIDescriptor(SrcRecordTy.getUnqualifiedType());
994 llvm::Value *DestRTTI =
995 CGF.CGM.GetAddrOfRTTIDescriptor(DestRecordTy.getUnqualifiedType());
996
997 llvm::Value *Offset;
998 std::tie(This, Offset, std::ignore) =
999 performBaseAdjustment(CGF, This, SrcRecordTy);
1000 llvm::Value *ThisPtr = This.getPointer();
1001 Offset = CGF.Builder.CreateTrunc(Offset, CGF.Int32Ty);
1002
1003 // PVOID __RTDynamicCast(
1004 // PVOID inptr,
1005 // LONG VfDelta,
1006 // PVOID SrcType,
1007 // PVOID TargetType,
1008 // BOOL isReference)
1009 llvm::Type *ArgTypes[] = {CGF.Int8PtrTy, CGF.Int32Ty, CGF.Int8PtrTy,
1010 CGF.Int8PtrTy, CGF.Int32Ty};
1011 llvm::FunctionCallee Function = CGF.CGM.CreateRuntimeFunction(
1012 llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false),
1013 "__RTDynamicCast");
1014 llvm::Value *Args[] = {
1015 ThisPtr, Offset, SrcRTTI, DestRTTI,
1016 llvm::ConstantInt::get(CGF.Int32Ty, DestTy->isReferenceType())};
1017 ThisPtr = CGF.EmitRuntimeCallOrInvoke(Function, Args);
1018 return CGF.Builder.CreateBitCast(ThisPtr, DestLTy);
1019 }
1020
1021 llvm::Value *
EmitDynamicCastToVoid(CodeGenFunction & CGF,Address Value,QualType SrcRecordTy,QualType DestTy)1022 MicrosoftCXXABI::EmitDynamicCastToVoid(CodeGenFunction &CGF, Address Value,
1023 QualType SrcRecordTy,
1024 QualType DestTy) {
1025 std::tie(Value, std::ignore, std::ignore) =
1026 performBaseAdjustment(CGF, Value, SrcRecordTy);
1027
1028 // PVOID __RTCastToVoid(
1029 // PVOID inptr)
1030 llvm::Type *ArgTypes[] = {CGF.Int8PtrTy};
1031 llvm::FunctionCallee Function = CGF.CGM.CreateRuntimeFunction(
1032 llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false),
1033 "__RTCastToVoid");
1034 llvm::Value *Args[] = {Value.getPointer()};
1035 return CGF.EmitRuntimeCall(Function, Args);
1036 }
1037
EmitBadCastCall(CodeGenFunction & CGF)1038 bool MicrosoftCXXABI::EmitBadCastCall(CodeGenFunction &CGF) {
1039 return false;
1040 }
1041
GetVirtualBaseClassOffset(CodeGenFunction & CGF,Address This,const CXXRecordDecl * ClassDecl,const CXXRecordDecl * BaseClassDecl)1042 llvm::Value *MicrosoftCXXABI::GetVirtualBaseClassOffset(
1043 CodeGenFunction &CGF, Address This, const CXXRecordDecl *ClassDecl,
1044 const CXXRecordDecl *BaseClassDecl) {
1045 const ASTContext &Context = getContext();
1046 int64_t VBPtrChars =
1047 Context.getASTRecordLayout(ClassDecl).getVBPtrOffset().getQuantity();
1048 llvm::Value *VBPtrOffset = llvm::ConstantInt::get(CGM.PtrDiffTy, VBPtrChars);
1049 CharUnits IntSize = Context.getTypeSizeInChars(Context.IntTy);
1050 CharUnits VBTableChars =
1051 IntSize *
1052 CGM.getMicrosoftVTableContext().getVBTableIndex(ClassDecl, BaseClassDecl);
1053 llvm::Value *VBTableOffset =
1054 llvm::ConstantInt::get(CGM.IntTy, VBTableChars.getQuantity());
1055
1056 llvm::Value *VBPtrToNewBase =
1057 GetVBaseOffsetFromVBPtr(CGF, This, VBPtrOffset, VBTableOffset);
1058 VBPtrToNewBase =
1059 CGF.Builder.CreateSExtOrBitCast(VBPtrToNewBase, CGM.PtrDiffTy);
1060 return CGF.Builder.CreateNSWAdd(VBPtrOffset, VBPtrToNewBase);
1061 }
1062
HasThisReturn(GlobalDecl GD) const1063 bool MicrosoftCXXABI::HasThisReturn(GlobalDecl GD) const {
1064 return isa<CXXConstructorDecl>(GD.getDecl());
1065 }
1066
isDeletingDtor(GlobalDecl GD)1067 static bool isDeletingDtor(GlobalDecl GD) {
1068 return isa<CXXDestructorDecl>(GD.getDecl()) &&
1069 GD.getDtorType() == Dtor_Deleting;
1070 }
1071
hasMostDerivedReturn(GlobalDecl GD) const1072 bool MicrosoftCXXABI::hasMostDerivedReturn(GlobalDecl GD) const {
1073 return isDeletingDtor(GD);
1074 }
1075
isTrivialForAArch64MSVC(const CXXRecordDecl * RD)1076 static bool isTrivialForAArch64MSVC(const CXXRecordDecl *RD) {
1077 // For AArch64, we use the C++14 definition of an aggregate, so we also
1078 // check for:
1079 // No private or protected non static data members.
1080 // No base classes
1081 // No virtual functions
1082 // Additionally, we need to ensure that there is a trivial copy assignment
1083 // operator, a trivial destructor and no user-provided constructors.
1084 if (RD->hasProtectedFields() || RD->hasPrivateFields())
1085 return false;
1086 if (RD->getNumBases() > 0)
1087 return false;
1088 if (RD->isPolymorphic())
1089 return false;
1090 if (RD->hasNonTrivialCopyAssignment())
1091 return false;
1092 for (const CXXConstructorDecl *Ctor : RD->ctors())
1093 if (Ctor->isUserProvided())
1094 return false;
1095 if (RD->hasNonTrivialDestructor())
1096 return false;
1097 return true;
1098 }
1099
classifyReturnType(CGFunctionInfo & FI) const1100 bool MicrosoftCXXABI::classifyReturnType(CGFunctionInfo &FI) const {
1101 const CXXRecordDecl *RD = FI.getReturnType()->getAsCXXRecordDecl();
1102 if (!RD)
1103 return false;
1104
1105 // Normally, the C++ concept of "is trivially copyable" is used to determine
1106 // if a struct can be returned directly. However, as MSVC and the language
1107 // have evolved, the definition of "trivially copyable" has changed, while the
1108 // ABI must remain stable. AArch64 uses the C++14 concept of an "aggregate",
1109 // while other ISAs use the older concept of "plain old data".
1110 bool isTrivialForABI = RD->isPOD();
1111 bool isAArch64 = CGM.getTarget().getTriple().isAArch64();
1112 if (isAArch64)
1113 isTrivialForABI = RD->canPassInRegisters() && isTrivialForAArch64MSVC(RD);
1114
1115 // MSVC always returns structs indirectly from C++ instance methods.
1116 bool isIndirectReturn = !isTrivialForABI || FI.isInstanceMethod();
1117
1118 if (isIndirectReturn) {
1119 CharUnits Align = CGM.getContext().getTypeAlignInChars(FI.getReturnType());
1120 FI.getReturnInfo() = ABIArgInfo::getIndirect(Align, /*ByVal=*/false);
1121
1122 // MSVC always passes `this` before the `sret` parameter.
1123 FI.getReturnInfo().setSRetAfterThis(FI.isInstanceMethod());
1124
1125 // On AArch64, use the `inreg` attribute if the object is considered to not
1126 // be trivially copyable, or if this is an instance method struct return.
1127 FI.getReturnInfo().setInReg(isAArch64);
1128
1129 return true;
1130 }
1131
1132 // Otherwise, use the C ABI rules.
1133 return false;
1134 }
1135
1136 llvm::BasicBlock *
EmitCtorCompleteObjectHandler(CodeGenFunction & CGF,const CXXRecordDecl * RD)1137 MicrosoftCXXABI::EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
1138 const CXXRecordDecl *RD) {
1139 llvm::Value *IsMostDerivedClass = getStructorImplicitParamValue(CGF);
1140 assert(IsMostDerivedClass &&
1141 "ctor for a class with virtual bases must have an implicit parameter");
1142 llvm::Value *IsCompleteObject =
1143 CGF.Builder.CreateIsNotNull(IsMostDerivedClass, "is_complete_object");
1144
1145 llvm::BasicBlock *CallVbaseCtorsBB = CGF.createBasicBlock("ctor.init_vbases");
1146 llvm::BasicBlock *SkipVbaseCtorsBB = CGF.createBasicBlock("ctor.skip_vbases");
1147 CGF.Builder.CreateCondBr(IsCompleteObject,
1148 CallVbaseCtorsBB, SkipVbaseCtorsBB);
1149
1150 CGF.EmitBlock(CallVbaseCtorsBB);
1151
1152 // Fill in the vbtable pointers here.
1153 EmitVBPtrStores(CGF, RD);
1154
1155 // CGF will put the base ctor calls in this basic block for us later.
1156
1157 return SkipVbaseCtorsBB;
1158 }
1159
1160 llvm::BasicBlock *
EmitDtorCompleteObjectHandler(CodeGenFunction & CGF)1161 MicrosoftCXXABI::EmitDtorCompleteObjectHandler(CodeGenFunction &CGF) {
1162 llvm::Value *IsMostDerivedClass = getStructorImplicitParamValue(CGF);
1163 assert(IsMostDerivedClass &&
1164 "ctor for a class with virtual bases must have an implicit parameter");
1165 llvm::Value *IsCompleteObject =
1166 CGF.Builder.CreateIsNotNull(IsMostDerivedClass, "is_complete_object");
1167
1168 llvm::BasicBlock *CallVbaseDtorsBB = CGF.createBasicBlock("Dtor.dtor_vbases");
1169 llvm::BasicBlock *SkipVbaseDtorsBB = CGF.createBasicBlock("Dtor.skip_vbases");
1170 CGF.Builder.CreateCondBr(IsCompleteObject,
1171 CallVbaseDtorsBB, SkipVbaseDtorsBB);
1172
1173 CGF.EmitBlock(CallVbaseDtorsBB);
1174 // CGF will put the base dtor calls in this basic block for us later.
1175
1176 return SkipVbaseDtorsBB;
1177 }
1178
initializeHiddenVirtualInheritanceMembers(CodeGenFunction & CGF,const CXXRecordDecl * RD)1179 void MicrosoftCXXABI::initializeHiddenVirtualInheritanceMembers(
1180 CodeGenFunction &CGF, const CXXRecordDecl *RD) {
1181 // In most cases, an override for a vbase virtual method can adjust
1182 // the "this" parameter by applying a constant offset.
1183 // However, this is not enough while a constructor or a destructor of some
1184 // class X is being executed if all the following conditions are met:
1185 // - X has virtual bases, (1)
1186 // - X overrides a virtual method M of a vbase Y, (2)
1187 // - X itself is a vbase of the most derived class.
1188 //
1189 // If (1) and (2) are true, the vtorDisp for vbase Y is a hidden member of X
1190 // which holds the extra amount of "this" adjustment we must do when we use
1191 // the X vftables (i.e. during X ctor or dtor).
1192 // Outside the ctors and dtors, the values of vtorDisps are zero.
1193
1194 const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
1195 typedef ASTRecordLayout::VBaseOffsetsMapTy VBOffsets;
1196 const VBOffsets &VBaseMap = Layout.getVBaseOffsetsMap();
1197 CGBuilderTy &Builder = CGF.Builder;
1198
1199 unsigned AS = getThisAddress(CGF).getAddressSpace();
1200 llvm::Value *Int8This = nullptr; // Initialize lazily.
1201
1202 for (const CXXBaseSpecifier &S : RD->vbases()) {
1203 const CXXRecordDecl *VBase = S.getType()->getAsCXXRecordDecl();
1204 auto I = VBaseMap.find(VBase);
1205 assert(I != VBaseMap.end());
1206 if (!I->second.hasVtorDisp())
1207 continue;
1208
1209 llvm::Value *VBaseOffset =
1210 GetVirtualBaseClassOffset(CGF, getThisAddress(CGF), RD, VBase);
1211 uint64_t ConstantVBaseOffset = I->second.VBaseOffset.getQuantity();
1212
1213 // vtorDisp_for_vbase = vbptr[vbase_idx] - offsetof(RD, vbase).
1214 llvm::Value *VtorDispValue = Builder.CreateSub(
1215 VBaseOffset, llvm::ConstantInt::get(CGM.PtrDiffTy, ConstantVBaseOffset),
1216 "vtordisp.value");
1217 VtorDispValue = Builder.CreateTruncOrBitCast(VtorDispValue, CGF.Int32Ty);
1218
1219 if (!Int8This)
1220 Int8This = Builder.CreateBitCast(getThisValue(CGF),
1221 CGF.Int8Ty->getPointerTo(AS));
1222 llvm::Value *VtorDispPtr = Builder.CreateInBoundsGEP(Int8This, VBaseOffset);
1223 // vtorDisp is always the 32-bits before the vbase in the class layout.
1224 VtorDispPtr = Builder.CreateConstGEP1_32(VtorDispPtr, -4);
1225 VtorDispPtr = Builder.CreateBitCast(
1226 VtorDispPtr, CGF.Int32Ty->getPointerTo(AS), "vtordisp.ptr");
1227
1228 Builder.CreateAlignedStore(VtorDispValue, VtorDispPtr,
1229 CharUnits::fromQuantity(4));
1230 }
1231 }
1232
hasDefaultCXXMethodCC(ASTContext & Context,const CXXMethodDecl * MD)1233 static bool hasDefaultCXXMethodCC(ASTContext &Context,
1234 const CXXMethodDecl *MD) {
1235 CallingConv ExpectedCallingConv = Context.getDefaultCallingConvention(
1236 /*IsVariadic=*/false, /*IsCXXMethod=*/true);
1237 CallingConv ActualCallingConv =
1238 MD->getType()->castAs<FunctionProtoType>()->getCallConv();
1239 return ExpectedCallingConv == ActualCallingConv;
1240 }
1241
EmitCXXConstructors(const CXXConstructorDecl * D)1242 void MicrosoftCXXABI::EmitCXXConstructors(const CXXConstructorDecl *D) {
1243 // There's only one constructor type in this ABI.
1244 CGM.EmitGlobal(GlobalDecl(D, Ctor_Complete));
1245
1246 // Exported default constructors either have a simple call-site where they use
1247 // the typical calling convention and have a single 'this' pointer for an
1248 // argument -or- they get a wrapper function which appropriately thunks to the
1249 // real default constructor. This thunk is the default constructor closure.
1250 if (D->hasAttr<DLLExportAttr>() && D->isDefaultConstructor() &&
1251 D->isDefined()) {
1252 if (!hasDefaultCXXMethodCC(getContext(), D) || D->getNumParams() != 0) {
1253 llvm::Function *Fn = getAddrOfCXXCtorClosure(D, Ctor_DefaultClosure);
1254 Fn->setLinkage(llvm::GlobalValue::WeakODRLinkage);
1255 CGM.setGVProperties(Fn, D);
1256 }
1257 }
1258 }
1259
EmitVBPtrStores(CodeGenFunction & CGF,const CXXRecordDecl * RD)1260 void MicrosoftCXXABI::EmitVBPtrStores(CodeGenFunction &CGF,
1261 const CXXRecordDecl *RD) {
1262 Address This = getThisAddress(CGF);
1263 This = CGF.Builder.CreateElementBitCast(This, CGM.Int8Ty, "this.int8");
1264 const ASTContext &Context = getContext();
1265 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1266
1267 const VBTableGlobals &VBGlobals = enumerateVBTables(RD);
1268 for (unsigned I = 0, E = VBGlobals.VBTables->size(); I != E; ++I) {
1269 const std::unique_ptr<VPtrInfo> &VBT = (*VBGlobals.VBTables)[I];
1270 llvm::GlobalVariable *GV = VBGlobals.Globals[I];
1271 const ASTRecordLayout &SubobjectLayout =
1272 Context.getASTRecordLayout(VBT->IntroducingObject);
1273 CharUnits Offs = VBT->NonVirtualOffset;
1274 Offs += SubobjectLayout.getVBPtrOffset();
1275 if (VBT->getVBaseWithVPtr())
1276 Offs += Layout.getVBaseClassOffset(VBT->getVBaseWithVPtr());
1277 Address VBPtr = CGF.Builder.CreateConstInBoundsByteGEP(This, Offs);
1278 llvm::Value *GVPtr =
1279 CGF.Builder.CreateConstInBoundsGEP2_32(GV->getValueType(), GV, 0, 0);
1280 VBPtr = CGF.Builder.CreateElementBitCast(VBPtr, GVPtr->getType(),
1281 "vbptr." + VBT->ObjectWithVPtr->getName());
1282 CGF.Builder.CreateStore(GVPtr, VBPtr);
1283 }
1284 }
1285
1286 CGCXXABI::AddedStructorArgCounts
buildStructorSignature(GlobalDecl GD,SmallVectorImpl<CanQualType> & ArgTys)1287 MicrosoftCXXABI::buildStructorSignature(GlobalDecl GD,
1288 SmallVectorImpl<CanQualType> &ArgTys) {
1289 AddedStructorArgCounts Added;
1290 // TODO: 'for base' flag
1291 if (isa<CXXDestructorDecl>(GD.getDecl()) &&
1292 GD.getDtorType() == Dtor_Deleting) {
1293 // The scalar deleting destructor takes an implicit int parameter.
1294 ArgTys.push_back(getContext().IntTy);
1295 ++Added.Suffix;
1296 }
1297 auto *CD = dyn_cast<CXXConstructorDecl>(GD.getDecl());
1298 if (!CD)
1299 return Added;
1300
1301 // All parameters are already in place except is_most_derived, which goes
1302 // after 'this' if it's variadic and last if it's not.
1303
1304 const CXXRecordDecl *Class = CD->getParent();
1305 const FunctionProtoType *FPT = CD->getType()->castAs<FunctionProtoType>();
1306 if (Class->getNumVBases()) {
1307 if (FPT->isVariadic()) {
1308 ArgTys.insert(ArgTys.begin() + 1, getContext().IntTy);
1309 ++Added.Prefix;
1310 } else {
1311 ArgTys.push_back(getContext().IntTy);
1312 ++Added.Suffix;
1313 }
1314 }
1315
1316 return Added;
1317 }
1318
setCXXDestructorDLLStorage(llvm::GlobalValue * GV,const CXXDestructorDecl * Dtor,CXXDtorType DT) const1319 void MicrosoftCXXABI::setCXXDestructorDLLStorage(llvm::GlobalValue *GV,
1320 const CXXDestructorDecl *Dtor,
1321 CXXDtorType DT) const {
1322 // Deleting destructor variants are never imported or exported. Give them the
1323 // default storage class.
1324 if (DT == Dtor_Deleting) {
1325 GV->setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass);
1326 } else {
1327 const NamedDecl *ND = Dtor;
1328 CGM.setDLLImportDLLExport(GV, ND);
1329 }
1330 }
1331
getCXXDestructorLinkage(GVALinkage Linkage,const CXXDestructorDecl * Dtor,CXXDtorType DT) const1332 llvm::GlobalValue::LinkageTypes MicrosoftCXXABI::getCXXDestructorLinkage(
1333 GVALinkage Linkage, const CXXDestructorDecl *Dtor, CXXDtorType DT) const {
1334 // Internal things are always internal, regardless of attributes. After this,
1335 // we know the thunk is externally visible.
1336 if (Linkage == GVA_Internal)
1337 return llvm::GlobalValue::InternalLinkage;
1338
1339 switch (DT) {
1340 case Dtor_Base:
1341 // The base destructor most closely tracks the user-declared constructor, so
1342 // we delegate back to the normal declarator case.
1343 return CGM.getLLVMLinkageForDeclarator(Dtor, Linkage,
1344 /*IsConstantVariable=*/false);
1345 case Dtor_Complete:
1346 // The complete destructor is like an inline function, but it may be
1347 // imported and therefore must be exported as well. This requires changing
1348 // the linkage if a DLL attribute is present.
1349 if (Dtor->hasAttr<DLLExportAttr>())
1350 return llvm::GlobalValue::WeakODRLinkage;
1351 if (Dtor->hasAttr<DLLImportAttr>())
1352 return llvm::GlobalValue::AvailableExternallyLinkage;
1353 return llvm::GlobalValue::LinkOnceODRLinkage;
1354 case Dtor_Deleting:
1355 // Deleting destructors are like inline functions. They have vague linkage
1356 // and are emitted everywhere they are used. They are internal if the class
1357 // is internal.
1358 return llvm::GlobalValue::LinkOnceODRLinkage;
1359 case Dtor_Comdat:
1360 llvm_unreachable("MS C++ ABI does not support comdat dtors");
1361 }
1362 llvm_unreachable("invalid dtor type");
1363 }
1364
EmitCXXDestructors(const CXXDestructorDecl * D)1365 void MicrosoftCXXABI::EmitCXXDestructors(const CXXDestructorDecl *D) {
1366 // The TU defining a dtor is only guaranteed to emit a base destructor. All
1367 // other destructor variants are delegating thunks.
1368 CGM.EmitGlobal(GlobalDecl(D, Dtor_Base));
1369
1370 // If the class is dllexported, emit the complete (vbase) destructor wherever
1371 // the base dtor is emitted.
1372 // FIXME: To match MSVC, this should only be done when the class is exported
1373 // with -fdllexport-inlines enabled.
1374 if (D->getParent()->getNumVBases() > 0 && D->hasAttr<DLLExportAttr>())
1375 CGM.EmitGlobal(GlobalDecl(D, Dtor_Complete));
1376 }
1377
1378 CharUnits
getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD)1379 MicrosoftCXXABI::getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) {
1380 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
1381
1382 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1383 // Complete destructors take a pointer to the complete object as a
1384 // parameter, thus don't need this adjustment.
1385 if (GD.getDtorType() == Dtor_Complete)
1386 return CharUnits();
1387
1388 // There's no Dtor_Base in vftable but it shares the this adjustment with
1389 // the deleting one, so look it up instead.
1390 GD = GlobalDecl(DD, Dtor_Deleting);
1391 }
1392
1393 MethodVFTableLocation ML =
1394 CGM.getMicrosoftVTableContext().getMethodVFTableLocation(GD);
1395 CharUnits Adjustment = ML.VFPtrOffset;
1396
1397 // Normal virtual instance methods need to adjust from the vfptr that first
1398 // defined the virtual method to the virtual base subobject, but destructors
1399 // do not. The vector deleting destructor thunk applies this adjustment for
1400 // us if necessary.
1401 if (isa<CXXDestructorDecl>(MD))
1402 Adjustment = CharUnits::Zero();
1403
1404 if (ML.VBase) {
1405 const ASTRecordLayout &DerivedLayout =
1406 getContext().getASTRecordLayout(MD->getParent());
1407 Adjustment += DerivedLayout.getVBaseClassOffset(ML.VBase);
1408 }
1409
1410 return Adjustment;
1411 }
1412
adjustThisArgumentForVirtualFunctionCall(CodeGenFunction & CGF,GlobalDecl GD,Address This,bool VirtualCall)1413 Address MicrosoftCXXABI::adjustThisArgumentForVirtualFunctionCall(
1414 CodeGenFunction &CGF, GlobalDecl GD, Address This,
1415 bool VirtualCall) {
1416 if (!VirtualCall) {
1417 // If the call of a virtual function is not virtual, we just have to
1418 // compensate for the adjustment the virtual function does in its prologue.
1419 CharUnits Adjustment = getVirtualFunctionPrologueThisAdjustment(GD);
1420 if (Adjustment.isZero())
1421 return This;
1422
1423 This = CGF.Builder.CreateElementBitCast(This, CGF.Int8Ty);
1424 assert(Adjustment.isPositive());
1425 return CGF.Builder.CreateConstByteGEP(This, Adjustment);
1426 }
1427
1428 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
1429
1430 GlobalDecl LookupGD = GD;
1431 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1432 // Complete dtors take a pointer to the complete object,
1433 // thus don't need adjustment.
1434 if (GD.getDtorType() == Dtor_Complete)
1435 return This;
1436
1437 // There's only Dtor_Deleting in vftable but it shares the this adjustment
1438 // with the base one, so look up the deleting one instead.
1439 LookupGD = GlobalDecl(DD, Dtor_Deleting);
1440 }
1441 MethodVFTableLocation ML =
1442 CGM.getMicrosoftVTableContext().getMethodVFTableLocation(LookupGD);
1443
1444 CharUnits StaticOffset = ML.VFPtrOffset;
1445
1446 // Base destructors expect 'this' to point to the beginning of the base
1447 // subobject, not the first vfptr that happens to contain the virtual dtor.
1448 // However, we still need to apply the virtual base adjustment.
1449 if (isa<CXXDestructorDecl>(MD) && GD.getDtorType() == Dtor_Base)
1450 StaticOffset = CharUnits::Zero();
1451
1452 Address Result = This;
1453 if (ML.VBase) {
1454 Result = CGF.Builder.CreateElementBitCast(Result, CGF.Int8Ty);
1455
1456 const CXXRecordDecl *Derived = MD->getParent();
1457 const CXXRecordDecl *VBase = ML.VBase;
1458 llvm::Value *VBaseOffset =
1459 GetVirtualBaseClassOffset(CGF, Result, Derived, VBase);
1460 llvm::Value *VBasePtr =
1461 CGF.Builder.CreateInBoundsGEP(Result.getPointer(), VBaseOffset);
1462 CharUnits VBaseAlign =
1463 CGF.CGM.getVBaseAlignment(Result.getAlignment(), Derived, VBase);
1464 Result = Address(VBasePtr, VBaseAlign);
1465 }
1466 if (!StaticOffset.isZero()) {
1467 assert(StaticOffset.isPositive());
1468 Result = CGF.Builder.CreateElementBitCast(Result, CGF.Int8Ty);
1469 if (ML.VBase) {
1470 // Non-virtual adjustment might result in a pointer outside the allocated
1471 // object, e.g. if the final overrider class is laid out after the virtual
1472 // base that declares a method in the most derived class.
1473 // FIXME: Update the code that emits this adjustment in thunks prologues.
1474 Result = CGF.Builder.CreateConstByteGEP(Result, StaticOffset);
1475 } else {
1476 Result = CGF.Builder.CreateConstInBoundsByteGEP(Result, StaticOffset);
1477 }
1478 }
1479 return Result;
1480 }
1481
addImplicitStructorParams(CodeGenFunction & CGF,QualType & ResTy,FunctionArgList & Params)1482 void MicrosoftCXXABI::addImplicitStructorParams(CodeGenFunction &CGF,
1483 QualType &ResTy,
1484 FunctionArgList &Params) {
1485 ASTContext &Context = getContext();
1486 const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
1487 assert(isa<CXXConstructorDecl>(MD) || isa<CXXDestructorDecl>(MD));
1488 if (isa<CXXConstructorDecl>(MD) && MD->getParent()->getNumVBases()) {
1489 auto *IsMostDerived = ImplicitParamDecl::Create(
1490 Context, /*DC=*/nullptr, CGF.CurGD.getDecl()->getLocation(),
1491 &Context.Idents.get("is_most_derived"), Context.IntTy,
1492 ImplicitParamDecl::Other);
1493 // The 'most_derived' parameter goes second if the ctor is variadic and last
1494 // if it's not. Dtors can't be variadic.
1495 const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>();
1496 if (FPT->isVariadic())
1497 Params.insert(Params.begin() + 1, IsMostDerived);
1498 else
1499 Params.push_back(IsMostDerived);
1500 getStructorImplicitParamDecl(CGF) = IsMostDerived;
1501 } else if (isDeletingDtor(CGF.CurGD)) {
1502 auto *ShouldDelete = ImplicitParamDecl::Create(
1503 Context, /*DC=*/nullptr, CGF.CurGD.getDecl()->getLocation(),
1504 &Context.Idents.get("should_call_delete"), Context.IntTy,
1505 ImplicitParamDecl::Other);
1506 Params.push_back(ShouldDelete);
1507 getStructorImplicitParamDecl(CGF) = ShouldDelete;
1508 }
1509 }
1510
EmitInstanceFunctionProlog(CodeGenFunction & CGF)1511 void MicrosoftCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) {
1512 // Naked functions have no prolog.
1513 if (CGF.CurFuncDecl && CGF.CurFuncDecl->hasAttr<NakedAttr>())
1514 return;
1515
1516 // Overridden virtual methods of non-primary bases need to adjust the incoming
1517 // 'this' pointer in the prologue. In this hierarchy, C::b will subtract
1518 // sizeof(void*) to adjust from B* to C*:
1519 // struct A { virtual void a(); };
1520 // struct B { virtual void b(); };
1521 // struct C : A, B { virtual void b(); };
1522 //
1523 // Leave the value stored in the 'this' alloca unadjusted, so that the
1524 // debugger sees the unadjusted value. Microsoft debuggers require this, and
1525 // will apply the ThisAdjustment in the method type information.
1526 // FIXME: Do something better for DWARF debuggers, which won't expect this,
1527 // without making our codegen depend on debug info settings.
1528 llvm::Value *This = loadIncomingCXXThis(CGF);
1529 const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
1530 if (!CGF.CurFuncIsThunk && MD->isVirtual()) {
1531 CharUnits Adjustment = getVirtualFunctionPrologueThisAdjustment(CGF.CurGD);
1532 if (!Adjustment.isZero()) {
1533 unsigned AS = cast<llvm::PointerType>(This->getType())->getAddressSpace();
1534 llvm::Type *charPtrTy = CGF.Int8Ty->getPointerTo(AS),
1535 *thisTy = This->getType();
1536 This = CGF.Builder.CreateBitCast(This, charPtrTy);
1537 assert(Adjustment.isPositive());
1538 This = CGF.Builder.CreateConstInBoundsGEP1_32(CGF.Int8Ty, This,
1539 -Adjustment.getQuantity());
1540 This = CGF.Builder.CreateBitCast(This, thisTy, "this.adjusted");
1541 }
1542 }
1543 setCXXABIThisValue(CGF, This);
1544
1545 // If this is a function that the ABI specifies returns 'this', initialize
1546 // the return slot to 'this' at the start of the function.
1547 //
1548 // Unlike the setting of return types, this is done within the ABI
1549 // implementation instead of by clients of CGCXXABI because:
1550 // 1) getThisValue is currently protected
1551 // 2) in theory, an ABI could implement 'this' returns some other way;
1552 // HasThisReturn only specifies a contract, not the implementation
1553 if (HasThisReturn(CGF.CurGD))
1554 CGF.Builder.CreateStore(getThisValue(CGF), CGF.ReturnValue);
1555 else if (hasMostDerivedReturn(CGF.CurGD))
1556 CGF.Builder.CreateStore(CGF.EmitCastToVoidPtr(getThisValue(CGF)),
1557 CGF.ReturnValue);
1558
1559 if (isa<CXXConstructorDecl>(MD) && MD->getParent()->getNumVBases()) {
1560 assert(getStructorImplicitParamDecl(CGF) &&
1561 "no implicit parameter for a constructor with virtual bases?");
1562 getStructorImplicitParamValue(CGF)
1563 = CGF.Builder.CreateLoad(
1564 CGF.GetAddrOfLocalVar(getStructorImplicitParamDecl(CGF)),
1565 "is_most_derived");
1566 }
1567
1568 if (isDeletingDtor(CGF.CurGD)) {
1569 assert(getStructorImplicitParamDecl(CGF) &&
1570 "no implicit parameter for a deleting destructor?");
1571 getStructorImplicitParamValue(CGF)
1572 = CGF.Builder.CreateLoad(
1573 CGF.GetAddrOfLocalVar(getStructorImplicitParamDecl(CGF)),
1574 "should_call_delete");
1575 }
1576 }
1577
getImplicitConstructorArgs(CodeGenFunction & CGF,const CXXConstructorDecl * D,CXXCtorType Type,bool ForVirtualBase,bool Delegating)1578 CGCXXABI::AddedStructorArgs MicrosoftCXXABI::getImplicitConstructorArgs(
1579 CodeGenFunction &CGF, const CXXConstructorDecl *D, CXXCtorType Type,
1580 bool ForVirtualBase, bool Delegating) {
1581 assert(Type == Ctor_Complete || Type == Ctor_Base);
1582
1583 // Check if we need a 'most_derived' parameter.
1584 if (!D->getParent()->getNumVBases())
1585 return AddedStructorArgs{};
1586
1587 // Add the 'most_derived' argument second if we are variadic or last if not.
1588 const FunctionProtoType *FPT = D->getType()->castAs<FunctionProtoType>();
1589 llvm::Value *MostDerivedArg;
1590 if (Delegating) {
1591 MostDerivedArg = getStructorImplicitParamValue(CGF);
1592 } else {
1593 MostDerivedArg = llvm::ConstantInt::get(CGM.Int32Ty, Type == Ctor_Complete);
1594 }
1595 if (FPT->isVariadic()) {
1596 return AddedStructorArgs::prefix({{MostDerivedArg, getContext().IntTy}});
1597 }
1598 return AddedStructorArgs::suffix({{MostDerivedArg, getContext().IntTy}});
1599 }
1600
getCXXDestructorImplicitParam(CodeGenFunction & CGF,const CXXDestructorDecl * DD,CXXDtorType Type,bool ForVirtualBase,bool Delegating)1601 llvm::Value *MicrosoftCXXABI::getCXXDestructorImplicitParam(
1602 CodeGenFunction &CGF, const CXXDestructorDecl *DD, CXXDtorType Type,
1603 bool ForVirtualBase, bool Delegating) {
1604 return nullptr;
1605 }
1606
EmitDestructorCall(CodeGenFunction & CGF,const CXXDestructorDecl * DD,CXXDtorType Type,bool ForVirtualBase,bool Delegating,Address This,QualType ThisTy)1607 void MicrosoftCXXABI::EmitDestructorCall(CodeGenFunction &CGF,
1608 const CXXDestructorDecl *DD,
1609 CXXDtorType Type, bool ForVirtualBase,
1610 bool Delegating, Address This,
1611 QualType ThisTy) {
1612 // Use the base destructor variant in place of the complete destructor variant
1613 // if the class has no virtual bases. This effectively implements some of the
1614 // -mconstructor-aliases optimization, but as part of the MS C++ ABI.
1615 if (Type == Dtor_Complete && DD->getParent()->getNumVBases() == 0)
1616 Type = Dtor_Base;
1617
1618 GlobalDecl GD(DD, Type);
1619 CGCallee Callee = CGCallee::forDirect(CGM.getAddrOfCXXStructor(GD), GD);
1620
1621 if (DD->isVirtual()) {
1622 assert(Type != CXXDtorType::Dtor_Deleting &&
1623 "The deleting destructor should only be called via a virtual call");
1624 This = adjustThisArgumentForVirtualFunctionCall(CGF, GlobalDecl(DD, Type),
1625 This, false);
1626 }
1627
1628 llvm::BasicBlock *BaseDtorEndBB = nullptr;
1629 if (ForVirtualBase && isa<CXXConstructorDecl>(CGF.CurCodeDecl)) {
1630 BaseDtorEndBB = EmitDtorCompleteObjectHandler(CGF);
1631 }
1632
1633 llvm::Value *Implicit =
1634 getCXXDestructorImplicitParam(CGF, DD, Type, ForVirtualBase,
1635 Delegating); // = nullptr
1636 CGF.EmitCXXDestructorCall(GD, Callee, This.getPointer(), ThisTy,
1637 /*ImplicitParam=*/Implicit,
1638 /*ImplicitParamTy=*/QualType(), nullptr);
1639 if (BaseDtorEndBB) {
1640 // Complete object handler should continue to be the remaining
1641 CGF.Builder.CreateBr(BaseDtorEndBB);
1642 CGF.EmitBlock(BaseDtorEndBB);
1643 }
1644 }
1645
emitVTableTypeMetadata(const VPtrInfo & Info,const CXXRecordDecl * RD,llvm::GlobalVariable * VTable)1646 void MicrosoftCXXABI::emitVTableTypeMetadata(const VPtrInfo &Info,
1647 const CXXRecordDecl *RD,
1648 llvm::GlobalVariable *VTable) {
1649 if (!CGM.getCodeGenOpts().LTOUnit)
1650 return;
1651
1652 // TODO: Should VirtualFunctionElimination also be supported here?
1653 // See similar handling in CodeGenModule::EmitVTableTypeMetadata.
1654 if (CGM.getCodeGenOpts().WholeProgramVTables) {
1655 llvm::DenseSet<const CXXRecordDecl *> Visited;
1656 llvm::GlobalObject::VCallVisibility TypeVis =
1657 CGM.GetVCallVisibilityLevel(RD, Visited);
1658 if (TypeVis != llvm::GlobalObject::VCallVisibilityPublic)
1659 VTable->setVCallVisibilityMetadata(TypeVis);
1660 }
1661
1662 // The location of the first virtual function pointer in the virtual table,
1663 // aka the "address point" on Itanium. This is at offset 0 if RTTI is
1664 // disabled, or sizeof(void*) if RTTI is enabled.
1665 CharUnits AddressPoint =
1666 getContext().getLangOpts().RTTIData
1667 ? getContext().toCharUnitsFromBits(
1668 getContext().getTargetInfo().getPointerWidth(0))
1669 : CharUnits::Zero();
1670
1671 if (Info.PathToIntroducingObject.empty()) {
1672 CGM.AddVTableTypeMetadata(VTable, AddressPoint, RD);
1673 return;
1674 }
1675
1676 // Add a bitset entry for the least derived base belonging to this vftable.
1677 CGM.AddVTableTypeMetadata(VTable, AddressPoint,
1678 Info.PathToIntroducingObject.back());
1679
1680 // Add a bitset entry for each derived class that is laid out at the same
1681 // offset as the least derived base.
1682 for (unsigned I = Info.PathToIntroducingObject.size() - 1; I != 0; --I) {
1683 const CXXRecordDecl *DerivedRD = Info.PathToIntroducingObject[I - 1];
1684 const CXXRecordDecl *BaseRD = Info.PathToIntroducingObject[I];
1685
1686 const ASTRecordLayout &Layout =
1687 getContext().getASTRecordLayout(DerivedRD);
1688 CharUnits Offset;
1689 auto VBI = Layout.getVBaseOffsetsMap().find(BaseRD);
1690 if (VBI == Layout.getVBaseOffsetsMap().end())
1691 Offset = Layout.getBaseClassOffset(BaseRD);
1692 else
1693 Offset = VBI->second.VBaseOffset;
1694 if (!Offset.isZero())
1695 return;
1696 CGM.AddVTableTypeMetadata(VTable, AddressPoint, DerivedRD);
1697 }
1698
1699 // Finally do the same for the most derived class.
1700 if (Info.FullOffsetInMDC.isZero())
1701 CGM.AddVTableTypeMetadata(VTable, AddressPoint, RD);
1702 }
1703
emitVTableDefinitions(CodeGenVTables & CGVT,const CXXRecordDecl * RD)1704 void MicrosoftCXXABI::emitVTableDefinitions(CodeGenVTables &CGVT,
1705 const CXXRecordDecl *RD) {
1706 MicrosoftVTableContext &VFTContext = CGM.getMicrosoftVTableContext();
1707 const VPtrInfoVector &VFPtrs = VFTContext.getVFPtrOffsets(RD);
1708
1709 for (const std::unique_ptr<VPtrInfo>& Info : VFPtrs) {
1710 llvm::GlobalVariable *VTable = getAddrOfVTable(RD, Info->FullOffsetInMDC);
1711 if (VTable->hasInitializer())
1712 continue;
1713
1714 const VTableLayout &VTLayout =
1715 VFTContext.getVFTableLayout(RD, Info->FullOffsetInMDC);
1716
1717 llvm::Constant *RTTI = nullptr;
1718 if (any_of(VTLayout.vtable_components(),
1719 [](const VTableComponent &VTC) { return VTC.isRTTIKind(); }))
1720 RTTI = getMSCompleteObjectLocator(RD, *Info);
1721
1722 ConstantInitBuilder builder(CGM);
1723 auto components = builder.beginStruct();
1724 CGVT.createVTableInitializer(components, VTLayout, RTTI,
1725 VTable->hasLocalLinkage());
1726 components.finishAndSetAsInitializer(VTable);
1727
1728 emitVTableTypeMetadata(*Info, RD, VTable);
1729 }
1730 }
1731
isVirtualOffsetNeededForVTableField(CodeGenFunction & CGF,CodeGenFunction::VPtr Vptr)1732 bool MicrosoftCXXABI::isVirtualOffsetNeededForVTableField(
1733 CodeGenFunction &CGF, CodeGenFunction::VPtr Vptr) {
1734 return Vptr.NearestVBase != nullptr;
1735 }
1736
getVTableAddressPointInStructor(CodeGenFunction & CGF,const CXXRecordDecl * VTableClass,BaseSubobject Base,const CXXRecordDecl * NearestVBase)1737 llvm::Value *MicrosoftCXXABI::getVTableAddressPointInStructor(
1738 CodeGenFunction &CGF, const CXXRecordDecl *VTableClass, BaseSubobject Base,
1739 const CXXRecordDecl *NearestVBase) {
1740 llvm::Constant *VTableAddressPoint = getVTableAddressPoint(Base, VTableClass);
1741 if (!VTableAddressPoint) {
1742 assert(Base.getBase()->getNumVBases() &&
1743 !getContext().getASTRecordLayout(Base.getBase()).hasOwnVFPtr());
1744 }
1745 return VTableAddressPoint;
1746 }
1747
mangleVFTableName(MicrosoftMangleContext & MangleContext,const CXXRecordDecl * RD,const VPtrInfo & VFPtr,SmallString<256> & Name)1748 static void mangleVFTableName(MicrosoftMangleContext &MangleContext,
1749 const CXXRecordDecl *RD, const VPtrInfo &VFPtr,
1750 SmallString<256> &Name) {
1751 llvm::raw_svector_ostream Out(Name);
1752 MangleContext.mangleCXXVFTable(RD, VFPtr.MangledPath, Out);
1753 }
1754
1755 llvm::Constant *
getVTableAddressPoint(BaseSubobject Base,const CXXRecordDecl * VTableClass)1756 MicrosoftCXXABI::getVTableAddressPoint(BaseSubobject Base,
1757 const CXXRecordDecl *VTableClass) {
1758 (void)getAddrOfVTable(VTableClass, Base.getBaseOffset());
1759 VFTableIdTy ID(VTableClass, Base.getBaseOffset());
1760 return VFTablesMap[ID];
1761 }
1762
getVTableAddressPointForConstExpr(BaseSubobject Base,const CXXRecordDecl * VTableClass)1763 llvm::Constant *MicrosoftCXXABI::getVTableAddressPointForConstExpr(
1764 BaseSubobject Base, const CXXRecordDecl *VTableClass) {
1765 llvm::Constant *VFTable = getVTableAddressPoint(Base, VTableClass);
1766 assert(VFTable && "Couldn't find a vftable for the given base?");
1767 return VFTable;
1768 }
1769
getAddrOfVTable(const CXXRecordDecl * RD,CharUnits VPtrOffset)1770 llvm::GlobalVariable *MicrosoftCXXABI::getAddrOfVTable(const CXXRecordDecl *RD,
1771 CharUnits VPtrOffset) {
1772 // getAddrOfVTable may return 0 if asked to get an address of a vtable which
1773 // shouldn't be used in the given record type. We want to cache this result in
1774 // VFTablesMap, thus a simple zero check is not sufficient.
1775
1776 VFTableIdTy ID(RD, VPtrOffset);
1777 VTablesMapTy::iterator I;
1778 bool Inserted;
1779 std::tie(I, Inserted) = VTablesMap.insert(std::make_pair(ID, nullptr));
1780 if (!Inserted)
1781 return I->second;
1782
1783 llvm::GlobalVariable *&VTable = I->second;
1784
1785 MicrosoftVTableContext &VTContext = CGM.getMicrosoftVTableContext();
1786 const VPtrInfoVector &VFPtrs = VTContext.getVFPtrOffsets(RD);
1787
1788 if (DeferredVFTables.insert(RD).second) {
1789 // We haven't processed this record type before.
1790 // Queue up this vtable for possible deferred emission.
1791 CGM.addDeferredVTable(RD);
1792
1793 #ifndef NDEBUG
1794 // Create all the vftables at once in order to make sure each vftable has
1795 // a unique mangled name.
1796 llvm::StringSet<> ObservedMangledNames;
1797 for (size_t J = 0, F = VFPtrs.size(); J != F; ++J) {
1798 SmallString<256> Name;
1799 mangleVFTableName(getMangleContext(), RD, *VFPtrs[J], Name);
1800 if (!ObservedMangledNames.insert(Name.str()).second)
1801 llvm_unreachable("Already saw this mangling before?");
1802 }
1803 #endif
1804 }
1805
1806 const std::unique_ptr<VPtrInfo> *VFPtrI = std::find_if(
1807 VFPtrs.begin(), VFPtrs.end(), [&](const std::unique_ptr<VPtrInfo>& VPI) {
1808 return VPI->FullOffsetInMDC == VPtrOffset;
1809 });
1810 if (VFPtrI == VFPtrs.end()) {
1811 VFTablesMap[ID] = nullptr;
1812 return nullptr;
1813 }
1814 const std::unique_ptr<VPtrInfo> &VFPtr = *VFPtrI;
1815
1816 SmallString<256> VFTableName;
1817 mangleVFTableName(getMangleContext(), RD, *VFPtr, VFTableName);
1818
1819 // Classes marked __declspec(dllimport) need vftables generated on the
1820 // import-side in order to support features like constexpr. No other
1821 // translation unit relies on the emission of the local vftable, translation
1822 // units are expected to generate them as needed.
1823 //
1824 // Because of this unique behavior, we maintain this logic here instead of
1825 // getVTableLinkage.
1826 llvm::GlobalValue::LinkageTypes VFTableLinkage =
1827 RD->hasAttr<DLLImportAttr>() ? llvm::GlobalValue::LinkOnceODRLinkage
1828 : CGM.getVTableLinkage(RD);
1829 bool VFTableComesFromAnotherTU =
1830 llvm::GlobalValue::isAvailableExternallyLinkage(VFTableLinkage) ||
1831 llvm::GlobalValue::isExternalLinkage(VFTableLinkage);
1832 bool VTableAliasIsRequred =
1833 !VFTableComesFromAnotherTU && getContext().getLangOpts().RTTIData;
1834
1835 if (llvm::GlobalValue *VFTable =
1836 CGM.getModule().getNamedGlobal(VFTableName)) {
1837 VFTablesMap[ID] = VFTable;
1838 VTable = VTableAliasIsRequred
1839 ? cast<llvm::GlobalVariable>(
1840 cast<llvm::GlobalAlias>(VFTable)->getBaseObject())
1841 : cast<llvm::GlobalVariable>(VFTable);
1842 return VTable;
1843 }
1844
1845 const VTableLayout &VTLayout =
1846 VTContext.getVFTableLayout(RD, VFPtr->FullOffsetInMDC);
1847 llvm::GlobalValue::LinkageTypes VTableLinkage =
1848 VTableAliasIsRequred ? llvm::GlobalValue::PrivateLinkage : VFTableLinkage;
1849
1850 StringRef VTableName = VTableAliasIsRequred ? StringRef() : VFTableName.str();
1851
1852 llvm::Type *VTableType = CGM.getVTables().getVTableType(VTLayout);
1853
1854 // Create a backing variable for the contents of VTable. The VTable may
1855 // or may not include space for a pointer to RTTI data.
1856 llvm::GlobalValue *VFTable;
1857 VTable = new llvm::GlobalVariable(CGM.getModule(), VTableType,
1858 /*isConstant=*/true, VTableLinkage,
1859 /*Initializer=*/nullptr, VTableName);
1860 VTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
1861
1862 llvm::Comdat *C = nullptr;
1863 if (!VFTableComesFromAnotherTU &&
1864 (llvm::GlobalValue::isWeakForLinker(VFTableLinkage) ||
1865 (llvm::GlobalValue::isLocalLinkage(VFTableLinkage) &&
1866 VTableAliasIsRequred)))
1867 C = CGM.getModule().getOrInsertComdat(VFTableName.str());
1868
1869 // Only insert a pointer into the VFTable for RTTI data if we are not
1870 // importing it. We never reference the RTTI data directly so there is no
1871 // need to make room for it.
1872 if (VTableAliasIsRequred) {
1873 llvm::Value *GEPIndices[] = {llvm::ConstantInt::get(CGM.Int32Ty, 0),
1874 llvm::ConstantInt::get(CGM.Int32Ty, 0),
1875 llvm::ConstantInt::get(CGM.Int32Ty, 1)};
1876 // Create a GEP which points just after the first entry in the VFTable,
1877 // this should be the location of the first virtual method.
1878 llvm::Constant *VTableGEP = llvm::ConstantExpr::getInBoundsGetElementPtr(
1879 VTable->getValueType(), VTable, GEPIndices);
1880 if (llvm::GlobalValue::isWeakForLinker(VFTableLinkage)) {
1881 VFTableLinkage = llvm::GlobalValue::ExternalLinkage;
1882 if (C)
1883 C->setSelectionKind(llvm::Comdat::Largest);
1884 }
1885 VFTable = llvm::GlobalAlias::create(CGM.Int8PtrTy,
1886 /*AddressSpace=*/0, VFTableLinkage,
1887 VFTableName.str(), VTableGEP,
1888 &CGM.getModule());
1889 VFTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
1890 } else {
1891 // We don't need a GlobalAlias to be a symbol for the VTable if we won't
1892 // be referencing any RTTI data.
1893 // The GlobalVariable will end up being an appropriate definition of the
1894 // VFTable.
1895 VFTable = VTable;
1896 }
1897 if (C)
1898 VTable->setComdat(C);
1899
1900 if (RD->hasAttr<DLLExportAttr>())
1901 VFTable->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);
1902
1903 VFTablesMap[ID] = VFTable;
1904 return VTable;
1905 }
1906
getVirtualFunctionPointer(CodeGenFunction & CGF,GlobalDecl GD,Address This,llvm::Type * Ty,SourceLocation Loc)1907 CGCallee MicrosoftCXXABI::getVirtualFunctionPointer(CodeGenFunction &CGF,
1908 GlobalDecl GD,
1909 Address This,
1910 llvm::Type *Ty,
1911 SourceLocation Loc) {
1912 CGBuilderTy &Builder = CGF.Builder;
1913
1914 Ty = Ty->getPointerTo()->getPointerTo();
1915 Address VPtr =
1916 adjustThisArgumentForVirtualFunctionCall(CGF, GD, This, true);
1917
1918 auto *MethodDecl = cast<CXXMethodDecl>(GD.getDecl());
1919 llvm::Value *VTable = CGF.GetVTablePtr(VPtr, Ty, MethodDecl->getParent());
1920
1921 MicrosoftVTableContext &VFTContext = CGM.getMicrosoftVTableContext();
1922 MethodVFTableLocation ML = VFTContext.getMethodVFTableLocation(GD);
1923
1924 // Compute the identity of the most derived class whose virtual table is
1925 // located at the MethodVFTableLocation ML.
1926 auto getObjectWithVPtr = [&] {
1927 return llvm::find_if(VFTContext.getVFPtrOffsets(
1928 ML.VBase ? ML.VBase : MethodDecl->getParent()),
1929 [&](const std::unique_ptr<VPtrInfo> &Info) {
1930 return Info->FullOffsetInMDC == ML.VFPtrOffset;
1931 })
1932 ->get()
1933 ->ObjectWithVPtr;
1934 };
1935
1936 llvm::Value *VFunc;
1937 if (CGF.ShouldEmitVTableTypeCheckedLoad(MethodDecl->getParent())) {
1938 VFunc = CGF.EmitVTableTypeCheckedLoad(
1939 getObjectWithVPtr(), VTable,
1940 ML.Index * CGM.getContext().getTargetInfo().getPointerWidth(0) / 8);
1941 } else {
1942 if (CGM.getCodeGenOpts().PrepareForLTO)
1943 CGF.EmitTypeMetadataCodeForVCall(getObjectWithVPtr(), VTable, Loc);
1944
1945 llvm::Value *VFuncPtr =
1946 Builder.CreateConstInBoundsGEP1_64(VTable, ML.Index, "vfn");
1947 VFunc = Builder.CreateAlignedLoad(VFuncPtr, CGF.getPointerAlign());
1948 }
1949
1950 CGCallee Callee(GD, VFunc);
1951 return Callee;
1952 }
1953
EmitVirtualDestructorCall(CodeGenFunction & CGF,const CXXDestructorDecl * Dtor,CXXDtorType DtorType,Address This,DeleteOrMemberCallExpr E)1954 llvm::Value *MicrosoftCXXABI::EmitVirtualDestructorCall(
1955 CodeGenFunction &CGF, const CXXDestructorDecl *Dtor, CXXDtorType DtorType,
1956 Address This, DeleteOrMemberCallExpr E) {
1957 auto *CE = E.dyn_cast<const CXXMemberCallExpr *>();
1958 auto *D = E.dyn_cast<const CXXDeleteExpr *>();
1959 assert((CE != nullptr) ^ (D != nullptr));
1960 assert(CE == nullptr || CE->arg_begin() == CE->arg_end());
1961 assert(DtorType == Dtor_Deleting || DtorType == Dtor_Complete);
1962
1963 // We have only one destructor in the vftable but can get both behaviors
1964 // by passing an implicit int parameter.
1965 GlobalDecl GD(Dtor, Dtor_Deleting);
1966 const CGFunctionInfo *FInfo =
1967 &CGM.getTypes().arrangeCXXStructorDeclaration(GD);
1968 llvm::FunctionType *Ty = CGF.CGM.getTypes().GetFunctionType(*FInfo);
1969 CGCallee Callee = CGCallee::forVirtual(CE, GD, This, Ty);
1970
1971 ASTContext &Context = getContext();
1972 llvm::Value *ImplicitParam = llvm::ConstantInt::get(
1973 llvm::IntegerType::getInt32Ty(CGF.getLLVMContext()),
1974 DtorType == Dtor_Deleting);
1975
1976 QualType ThisTy;
1977 if (CE) {
1978 ThisTy = CE->getObjectType();
1979 } else {
1980 ThisTy = D->getDestroyedType();
1981 }
1982
1983 This = adjustThisArgumentForVirtualFunctionCall(CGF, GD, This, true);
1984 RValue RV = CGF.EmitCXXDestructorCall(GD, Callee, This.getPointer(), ThisTy,
1985 ImplicitParam, Context.IntTy, CE);
1986 return RV.getScalarVal();
1987 }
1988
1989 const VBTableGlobals &
enumerateVBTables(const CXXRecordDecl * RD)1990 MicrosoftCXXABI::enumerateVBTables(const CXXRecordDecl *RD) {
1991 // At this layer, we can key the cache off of a single class, which is much
1992 // easier than caching each vbtable individually.
1993 llvm::DenseMap<const CXXRecordDecl*, VBTableGlobals>::iterator Entry;
1994 bool Added;
1995 std::tie(Entry, Added) =
1996 VBTablesMap.insert(std::make_pair(RD, VBTableGlobals()));
1997 VBTableGlobals &VBGlobals = Entry->second;
1998 if (!Added)
1999 return VBGlobals;
2000
2001 MicrosoftVTableContext &Context = CGM.getMicrosoftVTableContext();
2002 VBGlobals.VBTables = &Context.enumerateVBTables(RD);
2003
2004 // Cache the globals for all vbtables so we don't have to recompute the
2005 // mangled names.
2006 llvm::GlobalVariable::LinkageTypes Linkage = CGM.getVTableLinkage(RD);
2007 for (VPtrInfoVector::const_iterator I = VBGlobals.VBTables->begin(),
2008 E = VBGlobals.VBTables->end();
2009 I != E; ++I) {
2010 VBGlobals.Globals.push_back(getAddrOfVBTable(**I, RD, Linkage));
2011 }
2012
2013 return VBGlobals;
2014 }
2015
2016 llvm::Function *
EmitVirtualMemPtrThunk(const CXXMethodDecl * MD,const MethodVFTableLocation & ML)2017 MicrosoftCXXABI::EmitVirtualMemPtrThunk(const CXXMethodDecl *MD,
2018 const MethodVFTableLocation &ML) {
2019 assert(!isa<CXXConstructorDecl>(MD) && !isa<CXXDestructorDecl>(MD) &&
2020 "can't form pointers to ctors or virtual dtors");
2021
2022 // Calculate the mangled name.
2023 SmallString<256> ThunkName;
2024 llvm::raw_svector_ostream Out(ThunkName);
2025 getMangleContext().mangleVirtualMemPtrThunk(MD, ML, Out);
2026
2027 // If the thunk has been generated previously, just return it.
2028 if (llvm::GlobalValue *GV = CGM.getModule().getNamedValue(ThunkName))
2029 return cast<llvm::Function>(GV);
2030
2031 // Create the llvm::Function.
2032 const CGFunctionInfo &FnInfo =
2033 CGM.getTypes().arrangeUnprototypedMustTailThunk(MD);
2034 llvm::FunctionType *ThunkTy = CGM.getTypes().GetFunctionType(FnInfo);
2035 llvm::Function *ThunkFn =
2036 llvm::Function::Create(ThunkTy, llvm::Function::ExternalLinkage,
2037 ThunkName.str(), &CGM.getModule());
2038 assert(ThunkFn->getName() == ThunkName && "name was uniqued!");
2039
2040 ThunkFn->setLinkage(MD->isExternallyVisible()
2041 ? llvm::GlobalValue::LinkOnceODRLinkage
2042 : llvm::GlobalValue::InternalLinkage);
2043 if (MD->isExternallyVisible())
2044 ThunkFn->setComdat(CGM.getModule().getOrInsertComdat(ThunkFn->getName()));
2045
2046 CGM.SetLLVMFunctionAttributes(MD, FnInfo, ThunkFn);
2047 CGM.SetLLVMFunctionAttributesForDefinition(MD, ThunkFn);
2048
2049 // Add the "thunk" attribute so that LLVM knows that the return type is
2050 // meaningless. These thunks can be used to call functions with differing
2051 // return types, and the caller is required to cast the prototype
2052 // appropriately to extract the correct value.
2053 ThunkFn->addFnAttr("thunk");
2054
2055 // These thunks can be compared, so they are not unnamed.
2056 ThunkFn->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::None);
2057
2058 // Start codegen.
2059 CodeGenFunction CGF(CGM);
2060 CGF.CurGD = GlobalDecl(MD);
2061 CGF.CurFuncIsThunk = true;
2062
2063 // Build FunctionArgs, but only include the implicit 'this' parameter
2064 // declaration.
2065 FunctionArgList FunctionArgs;
2066 buildThisParam(CGF, FunctionArgs);
2067
2068 // Start defining the function.
2069 CGF.StartFunction(GlobalDecl(), FnInfo.getReturnType(), ThunkFn, FnInfo,
2070 FunctionArgs, MD->getLocation(), SourceLocation());
2071 setCXXABIThisValue(CGF, loadIncomingCXXThis(CGF));
2072
2073 // Load the vfptr and then callee from the vftable. The callee should have
2074 // adjusted 'this' so that the vfptr is at offset zero.
2075 llvm::Value *VTable = CGF.GetVTablePtr(
2076 getThisAddress(CGF), ThunkTy->getPointerTo()->getPointerTo(), MD->getParent());
2077
2078 llvm::Value *VFuncPtr =
2079 CGF.Builder.CreateConstInBoundsGEP1_64(VTable, ML.Index, "vfn");
2080 llvm::Value *Callee =
2081 CGF.Builder.CreateAlignedLoad(VFuncPtr, CGF.getPointerAlign());
2082
2083 CGF.EmitMustTailThunk(MD, getThisValue(CGF), {ThunkTy, Callee});
2084
2085 return ThunkFn;
2086 }
2087
emitVirtualInheritanceTables(const CXXRecordDecl * RD)2088 void MicrosoftCXXABI::emitVirtualInheritanceTables(const CXXRecordDecl *RD) {
2089 const VBTableGlobals &VBGlobals = enumerateVBTables(RD);
2090 for (unsigned I = 0, E = VBGlobals.VBTables->size(); I != E; ++I) {
2091 const std::unique_ptr<VPtrInfo>& VBT = (*VBGlobals.VBTables)[I];
2092 llvm::GlobalVariable *GV = VBGlobals.Globals[I];
2093 if (GV->isDeclaration())
2094 emitVBTableDefinition(*VBT, RD, GV);
2095 }
2096 }
2097
2098 llvm::GlobalVariable *
getAddrOfVBTable(const VPtrInfo & VBT,const CXXRecordDecl * RD,llvm::GlobalVariable::LinkageTypes Linkage)2099 MicrosoftCXXABI::getAddrOfVBTable(const VPtrInfo &VBT, const CXXRecordDecl *RD,
2100 llvm::GlobalVariable::LinkageTypes Linkage) {
2101 SmallString<256> OutName;
2102 llvm::raw_svector_ostream Out(OutName);
2103 getMangleContext().mangleCXXVBTable(RD, VBT.MangledPath, Out);
2104 StringRef Name = OutName.str();
2105
2106 llvm::ArrayType *VBTableType =
2107 llvm::ArrayType::get(CGM.IntTy, 1 + VBT.ObjectWithVPtr->getNumVBases());
2108
2109 assert(!CGM.getModule().getNamedGlobal(Name) &&
2110 "vbtable with this name already exists: mangling bug?");
2111 CharUnits Alignment =
2112 CGM.getContext().getTypeAlignInChars(CGM.getContext().IntTy);
2113 llvm::GlobalVariable *GV = CGM.CreateOrReplaceCXXRuntimeVariable(
2114 Name, VBTableType, Linkage, Alignment.getQuantity());
2115 GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
2116
2117 if (RD->hasAttr<DLLImportAttr>())
2118 GV->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass);
2119 else if (RD->hasAttr<DLLExportAttr>())
2120 GV->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);
2121
2122 if (!GV->hasExternalLinkage())
2123 emitVBTableDefinition(VBT, RD, GV);
2124
2125 return GV;
2126 }
2127
emitVBTableDefinition(const VPtrInfo & VBT,const CXXRecordDecl * RD,llvm::GlobalVariable * GV) const2128 void MicrosoftCXXABI::emitVBTableDefinition(const VPtrInfo &VBT,
2129 const CXXRecordDecl *RD,
2130 llvm::GlobalVariable *GV) const {
2131 const CXXRecordDecl *ObjectWithVPtr = VBT.ObjectWithVPtr;
2132
2133 assert(RD->getNumVBases() && ObjectWithVPtr->getNumVBases() &&
2134 "should only emit vbtables for classes with vbtables");
2135
2136 const ASTRecordLayout &BaseLayout =
2137 getContext().getASTRecordLayout(VBT.IntroducingObject);
2138 const ASTRecordLayout &DerivedLayout = getContext().getASTRecordLayout(RD);
2139
2140 SmallVector<llvm::Constant *, 4> Offsets(1 + ObjectWithVPtr->getNumVBases(),
2141 nullptr);
2142
2143 // The offset from ObjectWithVPtr's vbptr to itself always leads.
2144 CharUnits VBPtrOffset = BaseLayout.getVBPtrOffset();
2145 Offsets[0] = llvm::ConstantInt::get(CGM.IntTy, -VBPtrOffset.getQuantity());
2146
2147 MicrosoftVTableContext &Context = CGM.getMicrosoftVTableContext();
2148 for (const auto &I : ObjectWithVPtr->vbases()) {
2149 const CXXRecordDecl *VBase = I.getType()->getAsCXXRecordDecl();
2150 CharUnits Offset = DerivedLayout.getVBaseClassOffset(VBase);
2151 assert(!Offset.isNegative());
2152
2153 // Make it relative to the subobject vbptr.
2154 CharUnits CompleteVBPtrOffset = VBT.NonVirtualOffset + VBPtrOffset;
2155 if (VBT.getVBaseWithVPtr())
2156 CompleteVBPtrOffset +=
2157 DerivedLayout.getVBaseClassOffset(VBT.getVBaseWithVPtr());
2158 Offset -= CompleteVBPtrOffset;
2159
2160 unsigned VBIndex = Context.getVBTableIndex(ObjectWithVPtr, VBase);
2161 assert(Offsets[VBIndex] == nullptr && "The same vbindex seen twice?");
2162 Offsets[VBIndex] = llvm::ConstantInt::get(CGM.IntTy, Offset.getQuantity());
2163 }
2164
2165 assert(Offsets.size() ==
2166 cast<llvm::ArrayType>(cast<llvm::PointerType>(GV->getType())
2167 ->getElementType())->getNumElements());
2168 llvm::ArrayType *VBTableType =
2169 llvm::ArrayType::get(CGM.IntTy, Offsets.size());
2170 llvm::Constant *Init = llvm::ConstantArray::get(VBTableType, Offsets);
2171 GV->setInitializer(Init);
2172
2173 if (RD->hasAttr<DLLImportAttr>())
2174 GV->setLinkage(llvm::GlobalVariable::AvailableExternallyLinkage);
2175 }
2176
performThisAdjustment(CodeGenFunction & CGF,Address This,const ThisAdjustment & TA)2177 llvm::Value *MicrosoftCXXABI::performThisAdjustment(CodeGenFunction &CGF,
2178 Address This,
2179 const ThisAdjustment &TA) {
2180 if (TA.isEmpty())
2181 return This.getPointer();
2182
2183 This = CGF.Builder.CreateElementBitCast(This, CGF.Int8Ty);
2184
2185 llvm::Value *V;
2186 if (TA.Virtual.isEmpty()) {
2187 V = This.getPointer();
2188 } else {
2189 assert(TA.Virtual.Microsoft.VtordispOffset < 0);
2190 // Adjust the this argument based on the vtordisp value.
2191 Address VtorDispPtr =
2192 CGF.Builder.CreateConstInBoundsByteGEP(This,
2193 CharUnits::fromQuantity(TA.Virtual.Microsoft.VtordispOffset));
2194 VtorDispPtr = CGF.Builder.CreateElementBitCast(VtorDispPtr, CGF.Int32Ty);
2195 llvm::Value *VtorDisp = CGF.Builder.CreateLoad(VtorDispPtr, "vtordisp");
2196 V = CGF.Builder.CreateGEP(This.getPointer(),
2197 CGF.Builder.CreateNeg(VtorDisp));
2198
2199 // Unfortunately, having applied the vtordisp means that we no
2200 // longer really have a known alignment for the vbptr step.
2201 // We'll assume the vbptr is pointer-aligned.
2202
2203 if (TA.Virtual.Microsoft.VBPtrOffset) {
2204 // If the final overrider is defined in a virtual base other than the one
2205 // that holds the vfptr, we have to use a vtordispex thunk which looks up
2206 // the vbtable of the derived class.
2207 assert(TA.Virtual.Microsoft.VBPtrOffset > 0);
2208 assert(TA.Virtual.Microsoft.VBOffsetOffset >= 0);
2209 llvm::Value *VBPtr;
2210 llvm::Value *VBaseOffset =
2211 GetVBaseOffsetFromVBPtr(CGF, Address(V, CGF.getPointerAlign()),
2212 -TA.Virtual.Microsoft.VBPtrOffset,
2213 TA.Virtual.Microsoft.VBOffsetOffset, &VBPtr);
2214 V = CGF.Builder.CreateInBoundsGEP(VBPtr, VBaseOffset);
2215 }
2216 }
2217
2218 if (TA.NonVirtual) {
2219 // Non-virtual adjustment might result in a pointer outside the allocated
2220 // object, e.g. if the final overrider class is laid out after the virtual
2221 // base that declares a method in the most derived class.
2222 V = CGF.Builder.CreateConstGEP1_32(V, TA.NonVirtual);
2223 }
2224
2225 // Don't need to bitcast back, the call CodeGen will handle this.
2226 return V;
2227 }
2228
2229 llvm::Value *
performReturnAdjustment(CodeGenFunction & CGF,Address Ret,const ReturnAdjustment & RA)2230 MicrosoftCXXABI::performReturnAdjustment(CodeGenFunction &CGF, Address Ret,
2231 const ReturnAdjustment &RA) {
2232 if (RA.isEmpty())
2233 return Ret.getPointer();
2234
2235 auto OrigTy = Ret.getType();
2236 Ret = CGF.Builder.CreateElementBitCast(Ret, CGF.Int8Ty);
2237
2238 llvm::Value *V = Ret.getPointer();
2239 if (RA.Virtual.Microsoft.VBIndex) {
2240 assert(RA.Virtual.Microsoft.VBIndex > 0);
2241 int32_t IntSize = CGF.getIntSize().getQuantity();
2242 llvm::Value *VBPtr;
2243 llvm::Value *VBaseOffset =
2244 GetVBaseOffsetFromVBPtr(CGF, Ret, RA.Virtual.Microsoft.VBPtrOffset,
2245 IntSize * RA.Virtual.Microsoft.VBIndex, &VBPtr);
2246 V = CGF.Builder.CreateInBoundsGEP(VBPtr, VBaseOffset);
2247 }
2248
2249 if (RA.NonVirtual)
2250 V = CGF.Builder.CreateConstInBoundsGEP1_32(CGF.Int8Ty, V, RA.NonVirtual);
2251
2252 // Cast back to the original type.
2253 return CGF.Builder.CreateBitCast(V, OrigTy);
2254 }
2255
requiresArrayCookie(const CXXDeleteExpr * expr,QualType elementType)2256 bool MicrosoftCXXABI::requiresArrayCookie(const CXXDeleteExpr *expr,
2257 QualType elementType) {
2258 // Microsoft seems to completely ignore the possibility of a
2259 // two-argument usual deallocation function.
2260 return elementType.isDestructedType();
2261 }
2262
requiresArrayCookie(const CXXNewExpr * expr)2263 bool MicrosoftCXXABI::requiresArrayCookie(const CXXNewExpr *expr) {
2264 // Microsoft seems to completely ignore the possibility of a
2265 // two-argument usual deallocation function.
2266 return expr->getAllocatedType().isDestructedType();
2267 }
2268
getArrayCookieSizeImpl(QualType type)2269 CharUnits MicrosoftCXXABI::getArrayCookieSizeImpl(QualType type) {
2270 // The array cookie is always a size_t; we then pad that out to the
2271 // alignment of the element type.
2272 ASTContext &Ctx = getContext();
2273 return std::max(Ctx.getTypeSizeInChars(Ctx.getSizeType()),
2274 Ctx.getTypeAlignInChars(type));
2275 }
2276
readArrayCookieImpl(CodeGenFunction & CGF,Address allocPtr,CharUnits cookieSize)2277 llvm::Value *MicrosoftCXXABI::readArrayCookieImpl(CodeGenFunction &CGF,
2278 Address allocPtr,
2279 CharUnits cookieSize) {
2280 Address numElementsPtr =
2281 CGF.Builder.CreateElementBitCast(allocPtr, CGF.SizeTy);
2282 return CGF.Builder.CreateLoad(numElementsPtr);
2283 }
2284
InitializeArrayCookie(CodeGenFunction & CGF,Address newPtr,llvm::Value * numElements,const CXXNewExpr * expr,QualType elementType)2285 Address MicrosoftCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,
2286 Address newPtr,
2287 llvm::Value *numElements,
2288 const CXXNewExpr *expr,
2289 QualType elementType) {
2290 assert(requiresArrayCookie(expr));
2291
2292 // The size of the cookie.
2293 CharUnits cookieSize = getArrayCookieSizeImpl(elementType);
2294
2295 // Compute an offset to the cookie.
2296 Address cookiePtr = newPtr;
2297
2298 // Write the number of elements into the appropriate slot.
2299 Address numElementsPtr
2300 = CGF.Builder.CreateElementBitCast(cookiePtr, CGF.SizeTy);
2301 CGF.Builder.CreateStore(numElements, numElementsPtr);
2302
2303 // Finally, compute a pointer to the actual data buffer by skipping
2304 // over the cookie completely.
2305 return CGF.Builder.CreateConstInBoundsByteGEP(newPtr, cookieSize);
2306 }
2307
emitGlobalDtorWithTLRegDtor(CodeGenFunction & CGF,const VarDecl & VD,llvm::FunctionCallee Dtor,llvm::Constant * Addr)2308 static void emitGlobalDtorWithTLRegDtor(CodeGenFunction &CGF, const VarDecl &VD,
2309 llvm::FunctionCallee Dtor,
2310 llvm::Constant *Addr) {
2311 // Create a function which calls the destructor.
2312 llvm::Constant *DtorStub = CGF.createAtExitStub(VD, Dtor, Addr);
2313
2314 // extern "C" int __tlregdtor(void (*f)(void));
2315 llvm::FunctionType *TLRegDtorTy = llvm::FunctionType::get(
2316 CGF.IntTy, DtorStub->getType(), /*isVarArg=*/false);
2317
2318 llvm::FunctionCallee TLRegDtor = CGF.CGM.CreateRuntimeFunction(
2319 TLRegDtorTy, "__tlregdtor", llvm::AttributeList(), /*Local=*/true);
2320 if (llvm::Function *TLRegDtorFn =
2321 dyn_cast<llvm::Function>(TLRegDtor.getCallee()))
2322 TLRegDtorFn->setDoesNotThrow();
2323
2324 CGF.EmitNounwindRuntimeCall(TLRegDtor, DtorStub);
2325 }
2326
registerGlobalDtor(CodeGenFunction & CGF,const VarDecl & D,llvm::FunctionCallee Dtor,llvm::Constant * Addr)2327 void MicrosoftCXXABI::registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,
2328 llvm::FunctionCallee Dtor,
2329 llvm::Constant *Addr) {
2330 if (D.isNoDestroy(CGM.getContext()))
2331 return;
2332
2333 if (D.getTLSKind())
2334 return emitGlobalDtorWithTLRegDtor(CGF, D, Dtor, Addr);
2335
2336 // The default behavior is to use atexit.
2337 CGF.registerGlobalDtorWithAtExit(D, Dtor, Addr);
2338 }
2339
EmitThreadLocalInitFuncs(CodeGenModule & CGM,ArrayRef<const VarDecl * > CXXThreadLocals,ArrayRef<llvm::Function * > CXXThreadLocalInits,ArrayRef<const VarDecl * > CXXThreadLocalInitVars)2340 void MicrosoftCXXABI::EmitThreadLocalInitFuncs(
2341 CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals,
2342 ArrayRef<llvm::Function *> CXXThreadLocalInits,
2343 ArrayRef<const VarDecl *> CXXThreadLocalInitVars) {
2344 if (CXXThreadLocalInits.empty())
2345 return;
2346
2347 CGM.AppendLinkerOptions(CGM.getTarget().getTriple().getArch() ==
2348 llvm::Triple::x86
2349 ? "/include:___dyn_tls_init@12"
2350 : "/include:__dyn_tls_init");
2351
2352 // This will create a GV in the .CRT$XDU section. It will point to our
2353 // initialization function. The CRT will call all of these function
2354 // pointers at start-up time and, eventually, at thread-creation time.
2355 auto AddToXDU = [&CGM](llvm::Function *InitFunc) {
2356 llvm::GlobalVariable *InitFuncPtr = new llvm::GlobalVariable(
2357 CGM.getModule(), InitFunc->getType(), /*isConstant=*/true,
2358 llvm::GlobalVariable::InternalLinkage, InitFunc,
2359 Twine(InitFunc->getName(), "$initializer$"));
2360 InitFuncPtr->setSection(".CRT$XDU");
2361 // This variable has discardable linkage, we have to add it to @llvm.used to
2362 // ensure it won't get discarded.
2363 CGM.addUsedGlobal(InitFuncPtr);
2364 return InitFuncPtr;
2365 };
2366
2367 std::vector<llvm::Function *> NonComdatInits;
2368 for (size_t I = 0, E = CXXThreadLocalInitVars.size(); I != E; ++I) {
2369 llvm::GlobalVariable *GV = cast<llvm::GlobalVariable>(
2370 CGM.GetGlobalValue(CGM.getMangledName(CXXThreadLocalInitVars[I])));
2371 llvm::Function *F = CXXThreadLocalInits[I];
2372
2373 // If the GV is already in a comdat group, then we have to join it.
2374 if (llvm::Comdat *C = GV->getComdat())
2375 AddToXDU(F)->setComdat(C);
2376 else
2377 NonComdatInits.push_back(F);
2378 }
2379
2380 if (!NonComdatInits.empty()) {
2381 llvm::FunctionType *FTy =
2382 llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false);
2383 llvm::Function *InitFunc = CGM.CreateGlobalInitOrCleanUpFunction(
2384 FTy, "__tls_init", CGM.getTypes().arrangeNullaryFunction(),
2385 SourceLocation(), /*TLS=*/true);
2386 CodeGenFunction(CGM).GenerateCXXGlobalInitFunc(InitFunc, NonComdatInits);
2387
2388 AddToXDU(InitFunc);
2389 }
2390 }
2391
EmitThreadLocalVarDeclLValue(CodeGenFunction & CGF,const VarDecl * VD,QualType LValType)2392 LValue MicrosoftCXXABI::EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF,
2393 const VarDecl *VD,
2394 QualType LValType) {
2395 CGF.CGM.ErrorUnsupported(VD, "thread wrappers");
2396 return LValue();
2397 }
2398
getInitThreadEpochPtr(CodeGenModule & CGM)2399 static ConstantAddress getInitThreadEpochPtr(CodeGenModule &CGM) {
2400 StringRef VarName("_Init_thread_epoch");
2401 CharUnits Align = CGM.getIntAlign();
2402 if (auto *GV = CGM.getModule().getNamedGlobal(VarName))
2403 return ConstantAddress(GV, Align);
2404 auto *GV = new llvm::GlobalVariable(
2405 CGM.getModule(), CGM.IntTy,
2406 /*isConstant=*/false, llvm::GlobalVariable::ExternalLinkage,
2407 /*Initializer=*/nullptr, VarName,
2408 /*InsertBefore=*/nullptr, llvm::GlobalVariable::GeneralDynamicTLSModel);
2409 GV->setAlignment(Align.getAsAlign());
2410 return ConstantAddress(GV, Align);
2411 }
2412
getInitThreadHeaderFn(CodeGenModule & CGM)2413 static llvm::FunctionCallee getInitThreadHeaderFn(CodeGenModule &CGM) {
2414 llvm::FunctionType *FTy =
2415 llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()),
2416 CGM.IntTy->getPointerTo(), /*isVarArg=*/false);
2417 return CGM.CreateRuntimeFunction(
2418 FTy, "_Init_thread_header",
2419 llvm::AttributeList::get(CGM.getLLVMContext(),
2420 llvm::AttributeList::FunctionIndex,
2421 llvm::Attribute::NoUnwind),
2422 /*Local=*/true);
2423 }
2424
getInitThreadFooterFn(CodeGenModule & CGM)2425 static llvm::FunctionCallee getInitThreadFooterFn(CodeGenModule &CGM) {
2426 llvm::FunctionType *FTy =
2427 llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()),
2428 CGM.IntTy->getPointerTo(), /*isVarArg=*/false);
2429 return CGM.CreateRuntimeFunction(
2430 FTy, "_Init_thread_footer",
2431 llvm::AttributeList::get(CGM.getLLVMContext(),
2432 llvm::AttributeList::FunctionIndex,
2433 llvm::Attribute::NoUnwind),
2434 /*Local=*/true);
2435 }
2436
getInitThreadAbortFn(CodeGenModule & CGM)2437 static llvm::FunctionCallee getInitThreadAbortFn(CodeGenModule &CGM) {
2438 llvm::FunctionType *FTy =
2439 llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()),
2440 CGM.IntTy->getPointerTo(), /*isVarArg=*/false);
2441 return CGM.CreateRuntimeFunction(
2442 FTy, "_Init_thread_abort",
2443 llvm::AttributeList::get(CGM.getLLVMContext(),
2444 llvm::AttributeList::FunctionIndex,
2445 llvm::Attribute::NoUnwind),
2446 /*Local=*/true);
2447 }
2448
2449 namespace {
2450 struct ResetGuardBit final : EHScopeStack::Cleanup {
2451 Address Guard;
2452 unsigned GuardNum;
ResetGuardBit__anon400b770b0711::ResetGuardBit2453 ResetGuardBit(Address Guard, unsigned GuardNum)
2454 : Guard(Guard), GuardNum(GuardNum) {}
2455
Emit__anon400b770b0711::ResetGuardBit2456 void Emit(CodeGenFunction &CGF, Flags flags) override {
2457 // Reset the bit in the mask so that the static variable may be
2458 // reinitialized.
2459 CGBuilderTy &Builder = CGF.Builder;
2460 llvm::LoadInst *LI = Builder.CreateLoad(Guard);
2461 llvm::ConstantInt *Mask =
2462 llvm::ConstantInt::get(CGF.IntTy, ~(1ULL << GuardNum));
2463 Builder.CreateStore(Builder.CreateAnd(LI, Mask), Guard);
2464 }
2465 };
2466
2467 struct CallInitThreadAbort final : EHScopeStack::Cleanup {
2468 llvm::Value *Guard;
CallInitThreadAbort__anon400b770b0711::CallInitThreadAbort2469 CallInitThreadAbort(Address Guard) : Guard(Guard.getPointer()) {}
2470
Emit__anon400b770b0711::CallInitThreadAbort2471 void Emit(CodeGenFunction &CGF, Flags flags) override {
2472 // Calling _Init_thread_abort will reset the guard's state.
2473 CGF.EmitNounwindRuntimeCall(getInitThreadAbortFn(CGF.CGM), Guard);
2474 }
2475 };
2476 }
2477
EmitGuardedInit(CodeGenFunction & CGF,const VarDecl & D,llvm::GlobalVariable * GV,bool PerformInit)2478 void MicrosoftCXXABI::EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
2479 llvm::GlobalVariable *GV,
2480 bool PerformInit) {
2481 // MSVC only uses guards for static locals.
2482 if (!D.isStaticLocal()) {
2483 assert(GV->hasWeakLinkage() || GV->hasLinkOnceLinkage());
2484 // GlobalOpt is allowed to discard the initializer, so use linkonce_odr.
2485 llvm::Function *F = CGF.CurFn;
2486 F->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage);
2487 F->setComdat(CGM.getModule().getOrInsertComdat(F->getName()));
2488 CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit);
2489 return;
2490 }
2491
2492 bool ThreadlocalStatic = D.getTLSKind();
2493 bool ThreadsafeStatic = getContext().getLangOpts().ThreadsafeStatics;
2494
2495 // Thread-safe static variables which aren't thread-specific have a
2496 // per-variable guard.
2497 bool HasPerVariableGuard = ThreadsafeStatic && !ThreadlocalStatic;
2498
2499 CGBuilderTy &Builder = CGF.Builder;
2500 llvm::IntegerType *GuardTy = CGF.Int32Ty;
2501 llvm::ConstantInt *Zero = llvm::ConstantInt::get(GuardTy, 0);
2502 CharUnits GuardAlign = CharUnits::fromQuantity(4);
2503
2504 // Get the guard variable for this function if we have one already.
2505 GuardInfo *GI = nullptr;
2506 if (ThreadlocalStatic)
2507 GI = &ThreadLocalGuardVariableMap[D.getDeclContext()];
2508 else if (!ThreadsafeStatic)
2509 GI = &GuardVariableMap[D.getDeclContext()];
2510
2511 llvm::GlobalVariable *GuardVar = GI ? GI->Guard : nullptr;
2512 unsigned GuardNum;
2513 if (D.isExternallyVisible()) {
2514 // Externally visible variables have to be numbered in Sema to properly
2515 // handle unreachable VarDecls.
2516 GuardNum = getContext().getStaticLocalNumber(&D);
2517 assert(GuardNum > 0);
2518 GuardNum--;
2519 } else if (HasPerVariableGuard) {
2520 GuardNum = ThreadSafeGuardNumMap[D.getDeclContext()]++;
2521 } else {
2522 // Non-externally visible variables are numbered here in CodeGen.
2523 GuardNum = GI->BitIndex++;
2524 }
2525
2526 if (!HasPerVariableGuard && GuardNum >= 32) {
2527 if (D.isExternallyVisible())
2528 ErrorUnsupportedABI(CGF, "more than 32 guarded initializations");
2529 GuardNum %= 32;
2530 GuardVar = nullptr;
2531 }
2532
2533 if (!GuardVar) {
2534 // Mangle the name for the guard.
2535 SmallString<256> GuardName;
2536 {
2537 llvm::raw_svector_ostream Out(GuardName);
2538 if (HasPerVariableGuard)
2539 getMangleContext().mangleThreadSafeStaticGuardVariable(&D, GuardNum,
2540 Out);
2541 else
2542 getMangleContext().mangleStaticGuardVariable(&D, Out);
2543 }
2544
2545 // Create the guard variable with a zero-initializer. Just absorb linkage,
2546 // visibility and dll storage class from the guarded variable.
2547 GuardVar =
2548 new llvm::GlobalVariable(CGM.getModule(), GuardTy, /*isConstant=*/false,
2549 GV->getLinkage(), Zero, GuardName.str());
2550 GuardVar->setVisibility(GV->getVisibility());
2551 GuardVar->setDLLStorageClass(GV->getDLLStorageClass());
2552 GuardVar->setAlignment(GuardAlign.getAsAlign());
2553 if (GuardVar->isWeakForLinker())
2554 GuardVar->setComdat(
2555 CGM.getModule().getOrInsertComdat(GuardVar->getName()));
2556 if (D.getTLSKind())
2557 CGM.setTLSMode(GuardVar, D);
2558 if (GI && !HasPerVariableGuard)
2559 GI->Guard = GuardVar;
2560 }
2561
2562 ConstantAddress GuardAddr(GuardVar, GuardAlign);
2563
2564 assert(GuardVar->getLinkage() == GV->getLinkage() &&
2565 "static local from the same function had different linkage");
2566
2567 if (!HasPerVariableGuard) {
2568 // Pseudo code for the test:
2569 // if (!(GuardVar & MyGuardBit)) {
2570 // GuardVar |= MyGuardBit;
2571 // ... initialize the object ...;
2572 // }
2573
2574 // Test our bit from the guard variable.
2575 llvm::ConstantInt *Bit = llvm::ConstantInt::get(GuardTy, 1ULL << GuardNum);
2576 llvm::LoadInst *LI = Builder.CreateLoad(GuardAddr);
2577 llvm::Value *NeedsInit =
2578 Builder.CreateICmpEQ(Builder.CreateAnd(LI, Bit), Zero);
2579 llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init");
2580 llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end");
2581 CGF.EmitCXXGuardedInitBranch(NeedsInit, InitBlock, EndBlock,
2582 CodeGenFunction::GuardKind::VariableGuard, &D);
2583
2584 // Set our bit in the guard variable and emit the initializer and add a global
2585 // destructor if appropriate.
2586 CGF.EmitBlock(InitBlock);
2587 Builder.CreateStore(Builder.CreateOr(LI, Bit), GuardAddr);
2588 CGF.EHStack.pushCleanup<ResetGuardBit>(EHCleanup, GuardAddr, GuardNum);
2589 CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit);
2590 CGF.PopCleanupBlock();
2591 Builder.CreateBr(EndBlock);
2592
2593 // Continue.
2594 CGF.EmitBlock(EndBlock);
2595 } else {
2596 // Pseudo code for the test:
2597 // if (TSS > _Init_thread_epoch) {
2598 // _Init_thread_header(&TSS);
2599 // if (TSS == -1) {
2600 // ... initialize the object ...;
2601 // _Init_thread_footer(&TSS);
2602 // }
2603 // }
2604 //
2605 // The algorithm is almost identical to what can be found in the appendix
2606 // found in N2325.
2607
2608 // This BasicBLock determines whether or not we have any work to do.
2609 llvm::LoadInst *FirstGuardLoad = Builder.CreateLoad(GuardAddr);
2610 FirstGuardLoad->setOrdering(llvm::AtomicOrdering::Unordered);
2611 llvm::LoadInst *InitThreadEpoch =
2612 Builder.CreateLoad(getInitThreadEpochPtr(CGM));
2613 llvm::Value *IsUninitialized =
2614 Builder.CreateICmpSGT(FirstGuardLoad, InitThreadEpoch);
2615 llvm::BasicBlock *AttemptInitBlock = CGF.createBasicBlock("init.attempt");
2616 llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end");
2617 CGF.EmitCXXGuardedInitBranch(IsUninitialized, AttemptInitBlock, EndBlock,
2618 CodeGenFunction::GuardKind::VariableGuard, &D);
2619
2620 // This BasicBlock attempts to determine whether or not this thread is
2621 // responsible for doing the initialization.
2622 CGF.EmitBlock(AttemptInitBlock);
2623 CGF.EmitNounwindRuntimeCall(getInitThreadHeaderFn(CGM),
2624 GuardAddr.getPointer());
2625 llvm::LoadInst *SecondGuardLoad = Builder.CreateLoad(GuardAddr);
2626 SecondGuardLoad->setOrdering(llvm::AtomicOrdering::Unordered);
2627 llvm::Value *ShouldDoInit =
2628 Builder.CreateICmpEQ(SecondGuardLoad, getAllOnesInt());
2629 llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init");
2630 Builder.CreateCondBr(ShouldDoInit, InitBlock, EndBlock);
2631
2632 // Ok, we ended up getting selected as the initializing thread.
2633 CGF.EmitBlock(InitBlock);
2634 CGF.EHStack.pushCleanup<CallInitThreadAbort>(EHCleanup, GuardAddr);
2635 CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit);
2636 CGF.PopCleanupBlock();
2637 CGF.EmitNounwindRuntimeCall(getInitThreadFooterFn(CGM),
2638 GuardAddr.getPointer());
2639 Builder.CreateBr(EndBlock);
2640
2641 CGF.EmitBlock(EndBlock);
2642 }
2643 }
2644
isZeroInitializable(const MemberPointerType * MPT)2645 bool MicrosoftCXXABI::isZeroInitializable(const MemberPointerType *MPT) {
2646 // Null-ness for function memptrs only depends on the first field, which is
2647 // the function pointer. The rest don't matter, so we can zero initialize.
2648 if (MPT->isMemberFunctionPointer())
2649 return true;
2650
2651 // The virtual base adjustment field is always -1 for null, so if we have one
2652 // we can't zero initialize. The field offset is sometimes also -1 if 0 is a
2653 // valid field offset.
2654 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
2655 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2656 return (!inheritanceModelHasVBTableOffsetField(Inheritance) &&
2657 RD->nullFieldOffsetIsZero());
2658 }
2659
2660 llvm::Type *
ConvertMemberPointerType(const MemberPointerType * MPT)2661 MicrosoftCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) {
2662 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
2663 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2664 llvm::SmallVector<llvm::Type *, 4> fields;
2665 if (MPT->isMemberFunctionPointer())
2666 fields.push_back(CGM.VoidPtrTy); // FunctionPointerOrVirtualThunk
2667 else
2668 fields.push_back(CGM.IntTy); // FieldOffset
2669
2670 if (inheritanceModelHasNVOffsetField(MPT->isMemberFunctionPointer(),
2671 Inheritance))
2672 fields.push_back(CGM.IntTy);
2673 if (inheritanceModelHasVBPtrOffsetField(Inheritance))
2674 fields.push_back(CGM.IntTy);
2675 if (inheritanceModelHasVBTableOffsetField(Inheritance))
2676 fields.push_back(CGM.IntTy); // VirtualBaseAdjustmentOffset
2677
2678 if (fields.size() == 1)
2679 return fields[0];
2680 return llvm::StructType::get(CGM.getLLVMContext(), fields);
2681 }
2682
2683 void MicrosoftCXXABI::
GetNullMemberPointerFields(const MemberPointerType * MPT,llvm::SmallVectorImpl<llvm::Constant * > & fields)2684 GetNullMemberPointerFields(const MemberPointerType *MPT,
2685 llvm::SmallVectorImpl<llvm::Constant *> &fields) {
2686 assert(fields.empty());
2687 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
2688 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2689 if (MPT->isMemberFunctionPointer()) {
2690 // FunctionPointerOrVirtualThunk
2691 fields.push_back(llvm::Constant::getNullValue(CGM.VoidPtrTy));
2692 } else {
2693 if (RD->nullFieldOffsetIsZero())
2694 fields.push_back(getZeroInt()); // FieldOffset
2695 else
2696 fields.push_back(getAllOnesInt()); // FieldOffset
2697 }
2698
2699 if (inheritanceModelHasNVOffsetField(MPT->isMemberFunctionPointer(),
2700 Inheritance))
2701 fields.push_back(getZeroInt());
2702 if (inheritanceModelHasVBPtrOffsetField(Inheritance))
2703 fields.push_back(getZeroInt());
2704 if (inheritanceModelHasVBTableOffsetField(Inheritance))
2705 fields.push_back(getAllOnesInt());
2706 }
2707
2708 llvm::Constant *
EmitNullMemberPointer(const MemberPointerType * MPT)2709 MicrosoftCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) {
2710 llvm::SmallVector<llvm::Constant *, 4> fields;
2711 GetNullMemberPointerFields(MPT, fields);
2712 if (fields.size() == 1)
2713 return fields[0];
2714 llvm::Constant *Res = llvm::ConstantStruct::getAnon(fields);
2715 assert(Res->getType() == ConvertMemberPointerType(MPT));
2716 return Res;
2717 }
2718
2719 llvm::Constant *
EmitFullMemberPointer(llvm::Constant * FirstField,bool IsMemberFunction,const CXXRecordDecl * RD,CharUnits NonVirtualBaseAdjustment,unsigned VBTableIndex)2720 MicrosoftCXXABI::EmitFullMemberPointer(llvm::Constant *FirstField,
2721 bool IsMemberFunction,
2722 const CXXRecordDecl *RD,
2723 CharUnits NonVirtualBaseAdjustment,
2724 unsigned VBTableIndex) {
2725 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2726
2727 // Single inheritance class member pointer are represented as scalars instead
2728 // of aggregates.
2729 if (inheritanceModelHasOnlyOneField(IsMemberFunction, Inheritance))
2730 return FirstField;
2731
2732 llvm::SmallVector<llvm::Constant *, 4> fields;
2733 fields.push_back(FirstField);
2734
2735 if (inheritanceModelHasNVOffsetField(IsMemberFunction, Inheritance))
2736 fields.push_back(llvm::ConstantInt::get(
2737 CGM.IntTy, NonVirtualBaseAdjustment.getQuantity()));
2738
2739 if (inheritanceModelHasVBPtrOffsetField(Inheritance)) {
2740 CharUnits Offs = CharUnits::Zero();
2741 if (VBTableIndex)
2742 Offs = getContext().getASTRecordLayout(RD).getVBPtrOffset();
2743 fields.push_back(llvm::ConstantInt::get(CGM.IntTy, Offs.getQuantity()));
2744 }
2745
2746 // The rest of the fields are adjusted by conversions to a more derived class.
2747 if (inheritanceModelHasVBTableOffsetField(Inheritance))
2748 fields.push_back(llvm::ConstantInt::get(CGM.IntTy, VBTableIndex));
2749
2750 return llvm::ConstantStruct::getAnon(fields);
2751 }
2752
2753 llvm::Constant *
EmitMemberDataPointer(const MemberPointerType * MPT,CharUnits offset)2754 MicrosoftCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT,
2755 CharUnits offset) {
2756 return EmitMemberDataPointer(MPT->getMostRecentCXXRecordDecl(), offset);
2757 }
2758
EmitMemberDataPointer(const CXXRecordDecl * RD,CharUnits offset)2759 llvm::Constant *MicrosoftCXXABI::EmitMemberDataPointer(const CXXRecordDecl *RD,
2760 CharUnits offset) {
2761 if (RD->getMSInheritanceModel() ==
2762 MSInheritanceModel::Virtual)
2763 offset -= getContext().getOffsetOfBaseWithVBPtr(RD);
2764 llvm::Constant *FirstField =
2765 llvm::ConstantInt::get(CGM.IntTy, offset.getQuantity());
2766 return EmitFullMemberPointer(FirstField, /*IsMemberFunction=*/false, RD,
2767 CharUnits::Zero(), /*VBTableIndex=*/0);
2768 }
2769
EmitMemberPointer(const APValue & MP,QualType MPType)2770 llvm::Constant *MicrosoftCXXABI::EmitMemberPointer(const APValue &MP,
2771 QualType MPType) {
2772 const MemberPointerType *DstTy = MPType->castAs<MemberPointerType>();
2773 const ValueDecl *MPD = MP.getMemberPointerDecl();
2774 if (!MPD)
2775 return EmitNullMemberPointer(DstTy);
2776
2777 ASTContext &Ctx = getContext();
2778 ArrayRef<const CXXRecordDecl *> MemberPointerPath = MP.getMemberPointerPath();
2779
2780 llvm::Constant *C;
2781 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MPD)) {
2782 C = EmitMemberFunctionPointer(MD);
2783 } else {
2784 // For a pointer to data member, start off with the offset of the field in
2785 // the class in which it was declared, and convert from there if necessary.
2786 // For indirect field decls, get the outermost anonymous field and use the
2787 // parent class.
2788 CharUnits FieldOffset = Ctx.toCharUnitsFromBits(Ctx.getFieldOffset(MPD));
2789 const FieldDecl *FD = dyn_cast<FieldDecl>(MPD);
2790 if (!FD)
2791 FD = cast<FieldDecl>(*cast<IndirectFieldDecl>(MPD)->chain_begin());
2792 const CXXRecordDecl *RD = cast<CXXRecordDecl>(FD->getParent());
2793 RD = RD->getMostRecentNonInjectedDecl();
2794 C = EmitMemberDataPointer(RD, FieldOffset);
2795 }
2796
2797 if (!MemberPointerPath.empty()) {
2798 const CXXRecordDecl *SrcRD = cast<CXXRecordDecl>(MPD->getDeclContext());
2799 const Type *SrcRecTy = Ctx.getTypeDeclType(SrcRD).getTypePtr();
2800 const MemberPointerType *SrcTy =
2801 Ctx.getMemberPointerType(DstTy->getPointeeType(), SrcRecTy)
2802 ->castAs<MemberPointerType>();
2803
2804 bool DerivedMember = MP.isMemberPointerToDerivedMember();
2805 SmallVector<const CXXBaseSpecifier *, 4> DerivedToBasePath;
2806 const CXXRecordDecl *PrevRD = SrcRD;
2807 for (const CXXRecordDecl *PathElem : MemberPointerPath) {
2808 const CXXRecordDecl *Base = nullptr;
2809 const CXXRecordDecl *Derived = nullptr;
2810 if (DerivedMember) {
2811 Base = PathElem;
2812 Derived = PrevRD;
2813 } else {
2814 Base = PrevRD;
2815 Derived = PathElem;
2816 }
2817 for (const CXXBaseSpecifier &BS : Derived->bases())
2818 if (BS.getType()->getAsCXXRecordDecl()->getCanonicalDecl() ==
2819 Base->getCanonicalDecl())
2820 DerivedToBasePath.push_back(&BS);
2821 PrevRD = PathElem;
2822 }
2823 assert(DerivedToBasePath.size() == MemberPointerPath.size());
2824
2825 CastKind CK = DerivedMember ? CK_DerivedToBaseMemberPointer
2826 : CK_BaseToDerivedMemberPointer;
2827 C = EmitMemberPointerConversion(SrcTy, DstTy, CK, DerivedToBasePath.begin(),
2828 DerivedToBasePath.end(), C);
2829 }
2830 return C;
2831 }
2832
2833 llvm::Constant *
EmitMemberFunctionPointer(const CXXMethodDecl * MD)2834 MicrosoftCXXABI::EmitMemberFunctionPointer(const CXXMethodDecl *MD) {
2835 assert(MD->isInstance() && "Member function must not be static!");
2836
2837 CharUnits NonVirtualBaseAdjustment = CharUnits::Zero();
2838 const CXXRecordDecl *RD = MD->getParent()->getMostRecentNonInjectedDecl();
2839 CodeGenTypes &Types = CGM.getTypes();
2840
2841 unsigned VBTableIndex = 0;
2842 llvm::Constant *FirstField;
2843 const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>();
2844 if (!MD->isVirtual()) {
2845 llvm::Type *Ty;
2846 // Check whether the function has a computable LLVM signature.
2847 if (Types.isFuncTypeConvertible(FPT)) {
2848 // The function has a computable LLVM signature; use the correct type.
2849 Ty = Types.GetFunctionType(Types.arrangeCXXMethodDeclaration(MD));
2850 } else {
2851 // Use an arbitrary non-function type to tell GetAddrOfFunction that the
2852 // function type is incomplete.
2853 Ty = CGM.PtrDiffTy;
2854 }
2855 FirstField = CGM.GetAddrOfFunction(MD, Ty);
2856 } else {
2857 auto &VTableContext = CGM.getMicrosoftVTableContext();
2858 MethodVFTableLocation ML = VTableContext.getMethodVFTableLocation(MD);
2859 FirstField = EmitVirtualMemPtrThunk(MD, ML);
2860 // Include the vfptr adjustment if the method is in a non-primary vftable.
2861 NonVirtualBaseAdjustment += ML.VFPtrOffset;
2862 if (ML.VBase)
2863 VBTableIndex = VTableContext.getVBTableIndex(RD, ML.VBase) * 4;
2864 }
2865
2866 if (VBTableIndex == 0 &&
2867 RD->getMSInheritanceModel() ==
2868 MSInheritanceModel::Virtual)
2869 NonVirtualBaseAdjustment -= getContext().getOffsetOfBaseWithVBPtr(RD);
2870
2871 // The rest of the fields are common with data member pointers.
2872 FirstField = llvm::ConstantExpr::getBitCast(FirstField, CGM.VoidPtrTy);
2873 return EmitFullMemberPointer(FirstField, /*IsMemberFunction=*/true, RD,
2874 NonVirtualBaseAdjustment, VBTableIndex);
2875 }
2876
2877 /// Member pointers are the same if they're either bitwise identical *or* both
2878 /// null. Null-ness for function members is determined by the first field,
2879 /// while for data member pointers we must compare all fields.
2880 llvm::Value *
EmitMemberPointerComparison(CodeGenFunction & CGF,llvm::Value * L,llvm::Value * R,const MemberPointerType * MPT,bool Inequality)2881 MicrosoftCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF,
2882 llvm::Value *L,
2883 llvm::Value *R,
2884 const MemberPointerType *MPT,
2885 bool Inequality) {
2886 CGBuilderTy &Builder = CGF.Builder;
2887
2888 // Handle != comparisons by switching the sense of all boolean operations.
2889 llvm::ICmpInst::Predicate Eq;
2890 llvm::Instruction::BinaryOps And, Or;
2891 if (Inequality) {
2892 Eq = llvm::ICmpInst::ICMP_NE;
2893 And = llvm::Instruction::Or;
2894 Or = llvm::Instruction::And;
2895 } else {
2896 Eq = llvm::ICmpInst::ICMP_EQ;
2897 And = llvm::Instruction::And;
2898 Or = llvm::Instruction::Or;
2899 }
2900
2901 // If this is a single field member pointer (single inheritance), this is a
2902 // single icmp.
2903 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
2904 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2905 if (inheritanceModelHasOnlyOneField(MPT->isMemberFunctionPointer(),
2906 Inheritance))
2907 return Builder.CreateICmp(Eq, L, R);
2908
2909 // Compare the first field.
2910 llvm::Value *L0 = Builder.CreateExtractValue(L, 0, "lhs.0");
2911 llvm::Value *R0 = Builder.CreateExtractValue(R, 0, "rhs.0");
2912 llvm::Value *Cmp0 = Builder.CreateICmp(Eq, L0, R0, "memptr.cmp.first");
2913
2914 // Compare everything other than the first field.
2915 llvm::Value *Res = nullptr;
2916 llvm::StructType *LType = cast<llvm::StructType>(L->getType());
2917 for (unsigned I = 1, E = LType->getNumElements(); I != E; ++I) {
2918 llvm::Value *LF = Builder.CreateExtractValue(L, I);
2919 llvm::Value *RF = Builder.CreateExtractValue(R, I);
2920 llvm::Value *Cmp = Builder.CreateICmp(Eq, LF, RF, "memptr.cmp.rest");
2921 if (Res)
2922 Res = Builder.CreateBinOp(And, Res, Cmp);
2923 else
2924 Res = Cmp;
2925 }
2926
2927 // Check if the first field is 0 if this is a function pointer.
2928 if (MPT->isMemberFunctionPointer()) {
2929 // (l1 == r1 && ...) || l0 == 0
2930 llvm::Value *Zero = llvm::Constant::getNullValue(L0->getType());
2931 llvm::Value *IsZero = Builder.CreateICmp(Eq, L0, Zero, "memptr.cmp.iszero");
2932 Res = Builder.CreateBinOp(Or, Res, IsZero);
2933 }
2934
2935 // Combine the comparison of the first field, which must always be true for
2936 // this comparison to succeeed.
2937 return Builder.CreateBinOp(And, Res, Cmp0, "memptr.cmp");
2938 }
2939
2940 llvm::Value *
EmitMemberPointerIsNotNull(CodeGenFunction & CGF,llvm::Value * MemPtr,const MemberPointerType * MPT)2941 MicrosoftCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
2942 llvm::Value *MemPtr,
2943 const MemberPointerType *MPT) {
2944 CGBuilderTy &Builder = CGF.Builder;
2945 llvm::SmallVector<llvm::Constant *, 4> fields;
2946 // We only need one field for member functions.
2947 if (MPT->isMemberFunctionPointer())
2948 fields.push_back(llvm::Constant::getNullValue(CGM.VoidPtrTy));
2949 else
2950 GetNullMemberPointerFields(MPT, fields);
2951 assert(!fields.empty());
2952 llvm::Value *FirstField = MemPtr;
2953 if (MemPtr->getType()->isStructTy())
2954 FirstField = Builder.CreateExtractValue(MemPtr, 0);
2955 llvm::Value *Res = Builder.CreateICmpNE(FirstField, fields[0], "memptr.cmp0");
2956
2957 // For function member pointers, we only need to test the function pointer
2958 // field. The other fields if any can be garbage.
2959 if (MPT->isMemberFunctionPointer())
2960 return Res;
2961
2962 // Otherwise, emit a series of compares and combine the results.
2963 for (int I = 1, E = fields.size(); I < E; ++I) {
2964 llvm::Value *Field = Builder.CreateExtractValue(MemPtr, I);
2965 llvm::Value *Next = Builder.CreateICmpNE(Field, fields[I], "memptr.cmp");
2966 Res = Builder.CreateOr(Res, Next, "memptr.tobool");
2967 }
2968 return Res;
2969 }
2970
MemberPointerConstantIsNull(const MemberPointerType * MPT,llvm::Constant * Val)2971 bool MicrosoftCXXABI::MemberPointerConstantIsNull(const MemberPointerType *MPT,
2972 llvm::Constant *Val) {
2973 // Function pointers are null if the pointer in the first field is null.
2974 if (MPT->isMemberFunctionPointer()) {
2975 llvm::Constant *FirstField = Val->getType()->isStructTy() ?
2976 Val->getAggregateElement(0U) : Val;
2977 return FirstField->isNullValue();
2978 }
2979
2980 // If it's not a function pointer and it's zero initializable, we can easily
2981 // check zero.
2982 if (isZeroInitializable(MPT) && Val->isNullValue())
2983 return true;
2984
2985 // Otherwise, break down all the fields for comparison. Hopefully these
2986 // little Constants are reused, while a big null struct might not be.
2987 llvm::SmallVector<llvm::Constant *, 4> Fields;
2988 GetNullMemberPointerFields(MPT, Fields);
2989 if (Fields.size() == 1) {
2990 assert(Val->getType()->isIntegerTy());
2991 return Val == Fields[0];
2992 }
2993
2994 unsigned I, E;
2995 for (I = 0, E = Fields.size(); I != E; ++I) {
2996 if (Val->getAggregateElement(I) != Fields[I])
2997 break;
2998 }
2999 return I == E;
3000 }
3001
3002 llvm::Value *
GetVBaseOffsetFromVBPtr(CodeGenFunction & CGF,Address This,llvm::Value * VBPtrOffset,llvm::Value * VBTableOffset,llvm::Value ** VBPtrOut)3003 MicrosoftCXXABI::GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,
3004 Address This,
3005 llvm::Value *VBPtrOffset,
3006 llvm::Value *VBTableOffset,
3007 llvm::Value **VBPtrOut) {
3008 CGBuilderTy &Builder = CGF.Builder;
3009 // Load the vbtable pointer from the vbptr in the instance.
3010 This = Builder.CreateElementBitCast(This, CGM.Int8Ty);
3011 llvm::Value *VBPtr =
3012 Builder.CreateInBoundsGEP(This.getPointer(), VBPtrOffset, "vbptr");
3013 if (VBPtrOut) *VBPtrOut = VBPtr;
3014 VBPtr = Builder.CreateBitCast(VBPtr,
3015 CGM.Int32Ty->getPointerTo(0)->getPointerTo(This.getAddressSpace()));
3016
3017 CharUnits VBPtrAlign;
3018 if (auto CI = dyn_cast<llvm::ConstantInt>(VBPtrOffset)) {
3019 VBPtrAlign = This.getAlignment().alignmentAtOffset(
3020 CharUnits::fromQuantity(CI->getSExtValue()));
3021 } else {
3022 VBPtrAlign = CGF.getPointerAlign();
3023 }
3024
3025 llvm::Value *VBTable = Builder.CreateAlignedLoad(VBPtr, VBPtrAlign, "vbtable");
3026
3027 // Translate from byte offset to table index. It improves analyzability.
3028 llvm::Value *VBTableIndex = Builder.CreateAShr(
3029 VBTableOffset, llvm::ConstantInt::get(VBTableOffset->getType(), 2),
3030 "vbtindex", /*isExact=*/true);
3031
3032 // Load an i32 offset from the vb-table.
3033 llvm::Value *VBaseOffs = Builder.CreateInBoundsGEP(VBTable, VBTableIndex);
3034 VBaseOffs = Builder.CreateBitCast(VBaseOffs, CGM.Int32Ty->getPointerTo(0));
3035 return Builder.CreateAlignedLoad(VBaseOffs, CharUnits::fromQuantity(4),
3036 "vbase_offs");
3037 }
3038
3039 // Returns an adjusted base cast to i8*, since we do more address arithmetic on
3040 // it.
AdjustVirtualBase(CodeGenFunction & CGF,const Expr * E,const CXXRecordDecl * RD,Address Base,llvm::Value * VBTableOffset,llvm::Value * VBPtrOffset)3041 llvm::Value *MicrosoftCXXABI::AdjustVirtualBase(
3042 CodeGenFunction &CGF, const Expr *E, const CXXRecordDecl *RD,
3043 Address Base, llvm::Value *VBTableOffset, llvm::Value *VBPtrOffset) {
3044 CGBuilderTy &Builder = CGF.Builder;
3045 Base = Builder.CreateElementBitCast(Base, CGM.Int8Ty);
3046 llvm::BasicBlock *OriginalBB = nullptr;
3047 llvm::BasicBlock *SkipAdjustBB = nullptr;
3048 llvm::BasicBlock *VBaseAdjustBB = nullptr;
3049
3050 // In the unspecified inheritance model, there might not be a vbtable at all,
3051 // in which case we need to skip the virtual base lookup. If there is a
3052 // vbtable, the first entry is a no-op entry that gives back the original
3053 // base, so look for a virtual base adjustment offset of zero.
3054 if (VBPtrOffset) {
3055 OriginalBB = Builder.GetInsertBlock();
3056 VBaseAdjustBB = CGF.createBasicBlock("memptr.vadjust");
3057 SkipAdjustBB = CGF.createBasicBlock("memptr.skip_vadjust");
3058 llvm::Value *IsVirtual =
3059 Builder.CreateICmpNE(VBTableOffset, getZeroInt(),
3060 "memptr.is_vbase");
3061 Builder.CreateCondBr(IsVirtual, VBaseAdjustBB, SkipAdjustBB);
3062 CGF.EmitBlock(VBaseAdjustBB);
3063 }
3064
3065 // If we weren't given a dynamic vbptr offset, RD should be complete and we'll
3066 // know the vbptr offset.
3067 if (!VBPtrOffset) {
3068 CharUnits offs = CharUnits::Zero();
3069 if (!RD->hasDefinition()) {
3070 DiagnosticsEngine &Diags = CGF.CGM.getDiags();
3071 unsigned DiagID = Diags.getCustomDiagID(
3072 DiagnosticsEngine::Error,
3073 "member pointer representation requires a "
3074 "complete class type for %0 to perform this expression");
3075 Diags.Report(E->getExprLoc(), DiagID) << RD << E->getSourceRange();
3076 } else if (RD->getNumVBases())
3077 offs = getContext().getASTRecordLayout(RD).getVBPtrOffset();
3078 VBPtrOffset = llvm::ConstantInt::get(CGM.IntTy, offs.getQuantity());
3079 }
3080 llvm::Value *VBPtr = nullptr;
3081 llvm::Value *VBaseOffs =
3082 GetVBaseOffsetFromVBPtr(CGF, Base, VBPtrOffset, VBTableOffset, &VBPtr);
3083 llvm::Value *AdjustedBase = Builder.CreateInBoundsGEP(VBPtr, VBaseOffs);
3084
3085 // Merge control flow with the case where we didn't have to adjust.
3086 if (VBaseAdjustBB) {
3087 Builder.CreateBr(SkipAdjustBB);
3088 CGF.EmitBlock(SkipAdjustBB);
3089 llvm::PHINode *Phi = Builder.CreatePHI(CGM.Int8PtrTy, 2, "memptr.base");
3090 Phi->addIncoming(Base.getPointer(), OriginalBB);
3091 Phi->addIncoming(AdjustedBase, VBaseAdjustBB);
3092 return Phi;
3093 }
3094 return AdjustedBase;
3095 }
3096
EmitMemberDataPointerAddress(CodeGenFunction & CGF,const Expr * E,Address Base,llvm::Value * MemPtr,const MemberPointerType * MPT)3097 llvm::Value *MicrosoftCXXABI::EmitMemberDataPointerAddress(
3098 CodeGenFunction &CGF, const Expr *E, Address Base, llvm::Value *MemPtr,
3099 const MemberPointerType *MPT) {
3100 assert(MPT->isMemberDataPointer());
3101 unsigned AS = Base.getAddressSpace();
3102 llvm::Type *PType =
3103 CGF.ConvertTypeForMem(MPT->getPointeeType())->getPointerTo(AS);
3104 CGBuilderTy &Builder = CGF.Builder;
3105 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
3106 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
3107
3108 // Extract the fields we need, regardless of model. We'll apply them if we
3109 // have them.
3110 llvm::Value *FieldOffset = MemPtr;
3111 llvm::Value *VirtualBaseAdjustmentOffset = nullptr;
3112 llvm::Value *VBPtrOffset = nullptr;
3113 if (MemPtr->getType()->isStructTy()) {
3114 // We need to extract values.
3115 unsigned I = 0;
3116 FieldOffset = Builder.CreateExtractValue(MemPtr, I++);
3117 if (inheritanceModelHasVBPtrOffsetField(Inheritance))
3118 VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++);
3119 if (inheritanceModelHasVBTableOffsetField(Inheritance))
3120 VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++);
3121 }
3122
3123 llvm::Value *Addr;
3124 if (VirtualBaseAdjustmentOffset) {
3125 Addr = AdjustVirtualBase(CGF, E, RD, Base, VirtualBaseAdjustmentOffset,
3126 VBPtrOffset);
3127 } else {
3128 Addr = Base.getPointer();
3129 }
3130
3131 // Cast to char*.
3132 Addr = Builder.CreateBitCast(Addr, CGF.Int8Ty->getPointerTo(AS));
3133
3134 // Apply the offset, which we assume is non-null.
3135 Addr = Builder.CreateInBoundsGEP(Addr, FieldOffset, "memptr.offset");
3136
3137 // Cast the address to the appropriate pointer type, adopting the address
3138 // space of the base pointer.
3139 return Builder.CreateBitCast(Addr, PType);
3140 }
3141
3142 llvm::Value *
EmitMemberPointerConversion(CodeGenFunction & CGF,const CastExpr * E,llvm::Value * Src)3143 MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
3144 const CastExpr *E,
3145 llvm::Value *Src) {
3146 assert(E->getCastKind() == CK_DerivedToBaseMemberPointer ||
3147 E->getCastKind() == CK_BaseToDerivedMemberPointer ||
3148 E->getCastKind() == CK_ReinterpretMemberPointer);
3149
3150 // Use constant emission if we can.
3151 if (isa<llvm::Constant>(Src))
3152 return EmitMemberPointerConversion(E, cast<llvm::Constant>(Src));
3153
3154 // We may be adding or dropping fields from the member pointer, so we need
3155 // both types and the inheritance models of both records.
3156 const MemberPointerType *SrcTy =
3157 E->getSubExpr()->getType()->castAs<MemberPointerType>();
3158 const MemberPointerType *DstTy = E->getType()->castAs<MemberPointerType>();
3159 bool IsFunc = SrcTy->isMemberFunctionPointer();
3160
3161 // If the classes use the same null representation, reinterpret_cast is a nop.
3162 bool IsReinterpret = E->getCastKind() == CK_ReinterpretMemberPointer;
3163 if (IsReinterpret && IsFunc)
3164 return Src;
3165
3166 CXXRecordDecl *SrcRD = SrcTy->getMostRecentCXXRecordDecl();
3167 CXXRecordDecl *DstRD = DstTy->getMostRecentCXXRecordDecl();
3168 if (IsReinterpret &&
3169 SrcRD->nullFieldOffsetIsZero() == DstRD->nullFieldOffsetIsZero())
3170 return Src;
3171
3172 CGBuilderTy &Builder = CGF.Builder;
3173
3174 // Branch past the conversion if Src is null.
3175 llvm::Value *IsNotNull = EmitMemberPointerIsNotNull(CGF, Src, SrcTy);
3176 llvm::Constant *DstNull = EmitNullMemberPointer(DstTy);
3177
3178 // C++ 5.2.10p9: The null member pointer value is converted to the null member
3179 // pointer value of the destination type.
3180 if (IsReinterpret) {
3181 // For reinterpret casts, sema ensures that src and dst are both functions
3182 // or data and have the same size, which means the LLVM types should match.
3183 assert(Src->getType() == DstNull->getType());
3184 return Builder.CreateSelect(IsNotNull, Src, DstNull);
3185 }
3186
3187 llvm::BasicBlock *OriginalBB = Builder.GetInsertBlock();
3188 llvm::BasicBlock *ConvertBB = CGF.createBasicBlock("memptr.convert");
3189 llvm::BasicBlock *ContinueBB = CGF.createBasicBlock("memptr.converted");
3190 Builder.CreateCondBr(IsNotNull, ConvertBB, ContinueBB);
3191 CGF.EmitBlock(ConvertBB);
3192
3193 llvm::Value *Dst = EmitNonNullMemberPointerConversion(
3194 SrcTy, DstTy, E->getCastKind(), E->path_begin(), E->path_end(), Src,
3195 Builder);
3196
3197 Builder.CreateBr(ContinueBB);
3198
3199 // In the continuation, choose between DstNull and Dst.
3200 CGF.EmitBlock(ContinueBB);
3201 llvm::PHINode *Phi = Builder.CreatePHI(DstNull->getType(), 2, "memptr.converted");
3202 Phi->addIncoming(DstNull, OriginalBB);
3203 Phi->addIncoming(Dst, ConvertBB);
3204 return Phi;
3205 }
3206
EmitNonNullMemberPointerConversion(const MemberPointerType * SrcTy,const MemberPointerType * DstTy,CastKind CK,CastExpr::path_const_iterator PathBegin,CastExpr::path_const_iterator PathEnd,llvm::Value * Src,CGBuilderTy & Builder)3207 llvm::Value *MicrosoftCXXABI::EmitNonNullMemberPointerConversion(
3208 const MemberPointerType *SrcTy, const MemberPointerType *DstTy, CastKind CK,
3209 CastExpr::path_const_iterator PathBegin,
3210 CastExpr::path_const_iterator PathEnd, llvm::Value *Src,
3211 CGBuilderTy &Builder) {
3212 const CXXRecordDecl *SrcRD = SrcTy->getMostRecentCXXRecordDecl();
3213 const CXXRecordDecl *DstRD = DstTy->getMostRecentCXXRecordDecl();
3214 MSInheritanceModel SrcInheritance = SrcRD->getMSInheritanceModel();
3215 MSInheritanceModel DstInheritance = DstRD->getMSInheritanceModel();
3216 bool IsFunc = SrcTy->isMemberFunctionPointer();
3217 bool IsConstant = isa<llvm::Constant>(Src);
3218
3219 // Decompose src.
3220 llvm::Value *FirstField = Src;
3221 llvm::Value *NonVirtualBaseAdjustment = getZeroInt();
3222 llvm::Value *VirtualBaseAdjustmentOffset = getZeroInt();
3223 llvm::Value *VBPtrOffset = getZeroInt();
3224 if (!inheritanceModelHasOnlyOneField(IsFunc, SrcInheritance)) {
3225 // We need to extract values.
3226 unsigned I = 0;
3227 FirstField = Builder.CreateExtractValue(Src, I++);
3228 if (inheritanceModelHasNVOffsetField(IsFunc, SrcInheritance))
3229 NonVirtualBaseAdjustment = Builder.CreateExtractValue(Src, I++);
3230 if (inheritanceModelHasVBPtrOffsetField(SrcInheritance))
3231 VBPtrOffset = Builder.CreateExtractValue(Src, I++);
3232 if (inheritanceModelHasVBTableOffsetField(SrcInheritance))
3233 VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(Src, I++);
3234 }
3235
3236 bool IsDerivedToBase = (CK == CK_DerivedToBaseMemberPointer);
3237 const MemberPointerType *DerivedTy = IsDerivedToBase ? SrcTy : DstTy;
3238 const CXXRecordDecl *DerivedClass = DerivedTy->getMostRecentCXXRecordDecl();
3239
3240 // For data pointers, we adjust the field offset directly. For functions, we
3241 // have a separate field.
3242 llvm::Value *&NVAdjustField = IsFunc ? NonVirtualBaseAdjustment : FirstField;
3243
3244 // The virtual inheritance model has a quirk: the virtual base table is always
3245 // referenced when dereferencing a member pointer even if the member pointer
3246 // is non-virtual. This is accounted for by adjusting the non-virtual offset
3247 // to point backwards to the top of the MDC from the first VBase. Undo this
3248 // adjustment to normalize the member pointer.
3249 llvm::Value *SrcVBIndexEqZero =
3250 Builder.CreateICmpEQ(VirtualBaseAdjustmentOffset, getZeroInt());
3251 if (SrcInheritance == MSInheritanceModel::Virtual) {
3252 if (int64_t SrcOffsetToFirstVBase =
3253 getContext().getOffsetOfBaseWithVBPtr(SrcRD).getQuantity()) {
3254 llvm::Value *UndoSrcAdjustment = Builder.CreateSelect(
3255 SrcVBIndexEqZero,
3256 llvm::ConstantInt::get(CGM.IntTy, SrcOffsetToFirstVBase),
3257 getZeroInt());
3258 NVAdjustField = Builder.CreateNSWAdd(NVAdjustField, UndoSrcAdjustment);
3259 }
3260 }
3261
3262 // A non-zero vbindex implies that we are dealing with a source member in a
3263 // floating virtual base in addition to some non-virtual offset. If the
3264 // vbindex is zero, we are dealing with a source that exists in a non-virtual,
3265 // fixed, base. The difference between these two cases is that the vbindex +
3266 // nvoffset *always* point to the member regardless of what context they are
3267 // evaluated in so long as the vbindex is adjusted. A member inside a fixed
3268 // base requires explicit nv adjustment.
3269 llvm::Constant *BaseClassOffset = llvm::ConstantInt::get(
3270 CGM.IntTy,
3271 CGM.computeNonVirtualBaseClassOffset(DerivedClass, PathBegin, PathEnd)
3272 .getQuantity());
3273
3274 llvm::Value *NVDisp;
3275 if (IsDerivedToBase)
3276 NVDisp = Builder.CreateNSWSub(NVAdjustField, BaseClassOffset, "adj");
3277 else
3278 NVDisp = Builder.CreateNSWAdd(NVAdjustField, BaseClassOffset, "adj");
3279
3280 NVAdjustField = Builder.CreateSelect(SrcVBIndexEqZero, NVDisp, getZeroInt());
3281
3282 // Update the vbindex to an appropriate value in the destination because
3283 // SrcRD's vbtable might not be a strict prefix of the one in DstRD.
3284 llvm::Value *DstVBIndexEqZero = SrcVBIndexEqZero;
3285 if (inheritanceModelHasVBTableOffsetField(DstInheritance) &&
3286 inheritanceModelHasVBTableOffsetField(SrcInheritance)) {
3287 if (llvm::GlobalVariable *VDispMap =
3288 getAddrOfVirtualDisplacementMap(SrcRD, DstRD)) {
3289 llvm::Value *VBIndex = Builder.CreateExactUDiv(
3290 VirtualBaseAdjustmentOffset, llvm::ConstantInt::get(CGM.IntTy, 4));
3291 if (IsConstant) {
3292 llvm::Constant *Mapping = VDispMap->getInitializer();
3293 VirtualBaseAdjustmentOffset =
3294 Mapping->getAggregateElement(cast<llvm::Constant>(VBIndex));
3295 } else {
3296 llvm::Value *Idxs[] = {getZeroInt(), VBIndex};
3297 VirtualBaseAdjustmentOffset =
3298 Builder.CreateAlignedLoad(Builder.CreateInBoundsGEP(VDispMap, Idxs),
3299 CharUnits::fromQuantity(4));
3300 }
3301
3302 DstVBIndexEqZero =
3303 Builder.CreateICmpEQ(VirtualBaseAdjustmentOffset, getZeroInt());
3304 }
3305 }
3306
3307 // Set the VBPtrOffset to zero if the vbindex is zero. Otherwise, initialize
3308 // it to the offset of the vbptr.
3309 if (inheritanceModelHasVBPtrOffsetField(DstInheritance)) {
3310 llvm::Value *DstVBPtrOffset = llvm::ConstantInt::get(
3311 CGM.IntTy,
3312 getContext().getASTRecordLayout(DstRD).getVBPtrOffset().getQuantity());
3313 VBPtrOffset =
3314 Builder.CreateSelect(DstVBIndexEqZero, getZeroInt(), DstVBPtrOffset);
3315 }
3316
3317 // Likewise, apply a similar adjustment so that dereferencing the member
3318 // pointer correctly accounts for the distance between the start of the first
3319 // virtual base and the top of the MDC.
3320 if (DstInheritance == MSInheritanceModel::Virtual) {
3321 if (int64_t DstOffsetToFirstVBase =
3322 getContext().getOffsetOfBaseWithVBPtr(DstRD).getQuantity()) {
3323 llvm::Value *DoDstAdjustment = Builder.CreateSelect(
3324 DstVBIndexEqZero,
3325 llvm::ConstantInt::get(CGM.IntTy, DstOffsetToFirstVBase),
3326 getZeroInt());
3327 NVAdjustField = Builder.CreateNSWSub(NVAdjustField, DoDstAdjustment);
3328 }
3329 }
3330
3331 // Recompose dst from the null struct and the adjusted fields from src.
3332 llvm::Value *Dst;
3333 if (inheritanceModelHasOnlyOneField(IsFunc, DstInheritance)) {
3334 Dst = FirstField;
3335 } else {
3336 Dst = llvm::UndefValue::get(ConvertMemberPointerType(DstTy));
3337 unsigned Idx = 0;
3338 Dst = Builder.CreateInsertValue(Dst, FirstField, Idx++);
3339 if (inheritanceModelHasNVOffsetField(IsFunc, DstInheritance))
3340 Dst = Builder.CreateInsertValue(Dst, NonVirtualBaseAdjustment, Idx++);
3341 if (inheritanceModelHasVBPtrOffsetField(DstInheritance))
3342 Dst = Builder.CreateInsertValue(Dst, VBPtrOffset, Idx++);
3343 if (inheritanceModelHasVBTableOffsetField(DstInheritance))
3344 Dst = Builder.CreateInsertValue(Dst, VirtualBaseAdjustmentOffset, Idx++);
3345 }
3346 return Dst;
3347 }
3348
3349 llvm::Constant *
EmitMemberPointerConversion(const CastExpr * E,llvm::Constant * Src)3350 MicrosoftCXXABI::EmitMemberPointerConversion(const CastExpr *E,
3351 llvm::Constant *Src) {
3352 const MemberPointerType *SrcTy =
3353 E->getSubExpr()->getType()->castAs<MemberPointerType>();
3354 const MemberPointerType *DstTy = E->getType()->castAs<MemberPointerType>();
3355
3356 CastKind CK = E->getCastKind();
3357
3358 return EmitMemberPointerConversion(SrcTy, DstTy, CK, E->path_begin(),
3359 E->path_end(), Src);
3360 }
3361
EmitMemberPointerConversion(const MemberPointerType * SrcTy,const MemberPointerType * DstTy,CastKind CK,CastExpr::path_const_iterator PathBegin,CastExpr::path_const_iterator PathEnd,llvm::Constant * Src)3362 llvm::Constant *MicrosoftCXXABI::EmitMemberPointerConversion(
3363 const MemberPointerType *SrcTy, const MemberPointerType *DstTy, CastKind CK,
3364 CastExpr::path_const_iterator PathBegin,
3365 CastExpr::path_const_iterator PathEnd, llvm::Constant *Src) {
3366 assert(CK == CK_DerivedToBaseMemberPointer ||
3367 CK == CK_BaseToDerivedMemberPointer ||
3368 CK == CK_ReinterpretMemberPointer);
3369 // If src is null, emit a new null for dst. We can't return src because dst
3370 // might have a new representation.
3371 if (MemberPointerConstantIsNull(SrcTy, Src))
3372 return EmitNullMemberPointer(DstTy);
3373
3374 // We don't need to do anything for reinterpret_casts of non-null member
3375 // pointers. We should only get here when the two type representations have
3376 // the same size.
3377 if (CK == CK_ReinterpretMemberPointer)
3378 return Src;
3379
3380 CGBuilderTy Builder(CGM, CGM.getLLVMContext());
3381 auto *Dst = cast<llvm::Constant>(EmitNonNullMemberPointerConversion(
3382 SrcTy, DstTy, CK, PathBegin, PathEnd, Src, Builder));
3383
3384 return Dst;
3385 }
3386
EmitLoadOfMemberFunctionPointer(CodeGenFunction & CGF,const Expr * E,Address This,llvm::Value * & ThisPtrForCall,llvm::Value * MemPtr,const MemberPointerType * MPT)3387 CGCallee MicrosoftCXXABI::EmitLoadOfMemberFunctionPointer(
3388 CodeGenFunction &CGF, const Expr *E, Address This,
3389 llvm::Value *&ThisPtrForCall, llvm::Value *MemPtr,
3390 const MemberPointerType *MPT) {
3391 assert(MPT->isMemberFunctionPointer());
3392 const FunctionProtoType *FPT =
3393 MPT->getPointeeType()->castAs<FunctionProtoType>();
3394 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
3395 llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(
3396 CGM.getTypes().arrangeCXXMethodType(RD, FPT, /*FD=*/nullptr));
3397 CGBuilderTy &Builder = CGF.Builder;
3398
3399 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
3400
3401 // Extract the fields we need, regardless of model. We'll apply them if we
3402 // have them.
3403 llvm::Value *FunctionPointer = MemPtr;
3404 llvm::Value *NonVirtualBaseAdjustment = nullptr;
3405 llvm::Value *VirtualBaseAdjustmentOffset = nullptr;
3406 llvm::Value *VBPtrOffset = nullptr;
3407 if (MemPtr->getType()->isStructTy()) {
3408 // We need to extract values.
3409 unsigned I = 0;
3410 FunctionPointer = Builder.CreateExtractValue(MemPtr, I++);
3411 if (inheritanceModelHasNVOffsetField(MPT, Inheritance))
3412 NonVirtualBaseAdjustment = Builder.CreateExtractValue(MemPtr, I++);
3413 if (inheritanceModelHasVBPtrOffsetField(Inheritance))
3414 VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++);
3415 if (inheritanceModelHasVBTableOffsetField(Inheritance))
3416 VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++);
3417 }
3418
3419 if (VirtualBaseAdjustmentOffset) {
3420 ThisPtrForCall = AdjustVirtualBase(CGF, E, RD, This,
3421 VirtualBaseAdjustmentOffset, VBPtrOffset);
3422 } else {
3423 ThisPtrForCall = This.getPointer();
3424 }
3425
3426 if (NonVirtualBaseAdjustment) {
3427 // Apply the adjustment and cast back to the original struct type.
3428 llvm::Value *Ptr = Builder.CreateBitCast(ThisPtrForCall, CGF.Int8PtrTy);
3429 Ptr = Builder.CreateInBoundsGEP(Ptr, NonVirtualBaseAdjustment);
3430 ThisPtrForCall = Builder.CreateBitCast(Ptr, ThisPtrForCall->getType(),
3431 "this.adjusted");
3432 }
3433
3434 FunctionPointer =
3435 Builder.CreateBitCast(FunctionPointer, FTy->getPointerTo());
3436 CGCallee Callee(FPT, FunctionPointer);
3437 return Callee;
3438 }
3439
CreateMicrosoftCXXABI(CodeGenModule & CGM)3440 CGCXXABI *clang::CodeGen::CreateMicrosoftCXXABI(CodeGenModule &CGM) {
3441 return new MicrosoftCXXABI(CGM);
3442 }
3443
3444 // MS RTTI Overview:
3445 // The run time type information emitted by cl.exe contains 5 distinct types of
3446 // structures. Many of them reference each other.
3447 //
3448 // TypeInfo: Static classes that are returned by typeid.
3449 //
3450 // CompleteObjectLocator: Referenced by vftables. They contain information
3451 // required for dynamic casting, including OffsetFromTop. They also contain
3452 // a reference to the TypeInfo for the type and a reference to the
3453 // CompleteHierarchyDescriptor for the type.
3454 //
3455 // ClassHierarchyDescriptor: Contains information about a class hierarchy.
3456 // Used during dynamic_cast to walk a class hierarchy. References a base
3457 // class array and the size of said array.
3458 //
3459 // BaseClassArray: Contains a list of classes in a hierarchy. BaseClassArray is
3460 // somewhat of a misnomer because the most derived class is also in the list
3461 // as well as multiple copies of virtual bases (if they occur multiple times
3462 // in the hierarchy.) The BaseClassArray contains one BaseClassDescriptor for
3463 // every path in the hierarchy, in pre-order depth first order. Note, we do
3464 // not declare a specific llvm type for BaseClassArray, it's merely an array
3465 // of BaseClassDescriptor pointers.
3466 //
3467 // BaseClassDescriptor: Contains information about a class in a class hierarchy.
3468 // BaseClassDescriptor is also somewhat of a misnomer for the same reason that
3469 // BaseClassArray is. It contains information about a class within a
3470 // hierarchy such as: is this base is ambiguous and what is its offset in the
3471 // vbtable. The names of the BaseClassDescriptors have all of their fields
3472 // mangled into them so they can be aggressively deduplicated by the linker.
3473
getTypeInfoVTable(CodeGenModule & CGM)3474 static llvm::GlobalVariable *getTypeInfoVTable(CodeGenModule &CGM) {
3475 StringRef MangledName("??_7type_info@@6B@");
3476 if (auto VTable = CGM.getModule().getNamedGlobal(MangledName))
3477 return VTable;
3478 return new llvm::GlobalVariable(CGM.getModule(), CGM.Int8PtrTy,
3479 /*isConstant=*/true,
3480 llvm::GlobalVariable::ExternalLinkage,
3481 /*Initializer=*/nullptr, MangledName);
3482 }
3483
3484 namespace {
3485
3486 /// A Helper struct that stores information about a class in a class
3487 /// hierarchy. The information stored in these structs struct is used during
3488 /// the generation of ClassHierarchyDescriptors and BaseClassDescriptors.
3489 // During RTTI creation, MSRTTIClasses are stored in a contiguous array with
3490 // implicit depth first pre-order tree connectivity. getFirstChild and
3491 // getNextSibling allow us to walk the tree efficiently.
3492 struct MSRTTIClass {
3493 enum {
3494 IsPrivateOnPath = 1 | 8,
3495 IsAmbiguous = 2,
3496 IsPrivate = 4,
3497 IsVirtual = 16,
3498 HasHierarchyDescriptor = 64
3499 };
MSRTTIClass__anon400b770b0811::MSRTTIClass3500 MSRTTIClass(const CXXRecordDecl *RD) : RD(RD) {}
3501 uint32_t initialize(const MSRTTIClass *Parent,
3502 const CXXBaseSpecifier *Specifier);
3503
getFirstChild__anon400b770b0811::MSRTTIClass3504 MSRTTIClass *getFirstChild() { return this + 1; }
getNextChild__anon400b770b0811::MSRTTIClass3505 static MSRTTIClass *getNextChild(MSRTTIClass *Child) {
3506 return Child + 1 + Child->NumBases;
3507 }
3508
3509 const CXXRecordDecl *RD, *VirtualRoot;
3510 uint32_t Flags, NumBases, OffsetInVBase;
3511 };
3512
3513 /// Recursively initialize the base class array.
initialize(const MSRTTIClass * Parent,const CXXBaseSpecifier * Specifier)3514 uint32_t MSRTTIClass::initialize(const MSRTTIClass *Parent,
3515 const CXXBaseSpecifier *Specifier) {
3516 Flags = HasHierarchyDescriptor;
3517 if (!Parent) {
3518 VirtualRoot = nullptr;
3519 OffsetInVBase = 0;
3520 } else {
3521 if (Specifier->getAccessSpecifier() != AS_public)
3522 Flags |= IsPrivate | IsPrivateOnPath;
3523 if (Specifier->isVirtual()) {
3524 Flags |= IsVirtual;
3525 VirtualRoot = RD;
3526 OffsetInVBase = 0;
3527 } else {
3528 if (Parent->Flags & IsPrivateOnPath)
3529 Flags |= IsPrivateOnPath;
3530 VirtualRoot = Parent->VirtualRoot;
3531 OffsetInVBase = Parent->OffsetInVBase + RD->getASTContext()
3532 .getASTRecordLayout(Parent->RD).getBaseClassOffset(RD).getQuantity();
3533 }
3534 }
3535 NumBases = 0;
3536 MSRTTIClass *Child = getFirstChild();
3537 for (const CXXBaseSpecifier &Base : RD->bases()) {
3538 NumBases += Child->initialize(this, &Base) + 1;
3539 Child = getNextChild(Child);
3540 }
3541 return NumBases;
3542 }
3543
getLinkageForRTTI(QualType Ty)3544 static llvm::GlobalValue::LinkageTypes getLinkageForRTTI(QualType Ty) {
3545 switch (Ty->getLinkage()) {
3546 case NoLinkage:
3547 case InternalLinkage:
3548 case UniqueExternalLinkage:
3549 return llvm::GlobalValue::InternalLinkage;
3550
3551 case VisibleNoLinkage:
3552 case ModuleInternalLinkage:
3553 case ModuleLinkage:
3554 case ExternalLinkage:
3555 return llvm::GlobalValue::LinkOnceODRLinkage;
3556 }
3557 llvm_unreachable("Invalid linkage!");
3558 }
3559
3560 /// An ephemeral helper class for building MS RTTI types. It caches some
3561 /// calls to the module and information about the most derived class in a
3562 /// hierarchy.
3563 struct MSRTTIBuilder {
3564 enum {
3565 HasBranchingHierarchy = 1,
3566 HasVirtualBranchingHierarchy = 2,
3567 HasAmbiguousBases = 4
3568 };
3569
MSRTTIBuilder__anon400b770b0811::MSRTTIBuilder3570 MSRTTIBuilder(MicrosoftCXXABI &ABI, const CXXRecordDecl *RD)
3571 : CGM(ABI.CGM), Context(CGM.getContext()),
3572 VMContext(CGM.getLLVMContext()), Module(CGM.getModule()), RD(RD),
3573 Linkage(getLinkageForRTTI(CGM.getContext().getTagDeclType(RD))),
3574 ABI(ABI) {}
3575
3576 llvm::GlobalVariable *getBaseClassDescriptor(const MSRTTIClass &Classes);
3577 llvm::GlobalVariable *
3578 getBaseClassArray(SmallVectorImpl<MSRTTIClass> &Classes);
3579 llvm::GlobalVariable *getClassHierarchyDescriptor();
3580 llvm::GlobalVariable *getCompleteObjectLocator(const VPtrInfo &Info);
3581
3582 CodeGenModule &CGM;
3583 ASTContext &Context;
3584 llvm::LLVMContext &VMContext;
3585 llvm::Module &Module;
3586 const CXXRecordDecl *RD;
3587 llvm::GlobalVariable::LinkageTypes Linkage;
3588 MicrosoftCXXABI &ABI;
3589 };
3590
3591 } // namespace
3592
3593 /// Recursively serializes a class hierarchy in pre-order depth first
3594 /// order.
serializeClassHierarchy(SmallVectorImpl<MSRTTIClass> & Classes,const CXXRecordDecl * RD)3595 static void serializeClassHierarchy(SmallVectorImpl<MSRTTIClass> &Classes,
3596 const CXXRecordDecl *RD) {
3597 Classes.push_back(MSRTTIClass(RD));
3598 for (const CXXBaseSpecifier &Base : RD->bases())
3599 serializeClassHierarchy(Classes, Base.getType()->getAsCXXRecordDecl());
3600 }
3601
3602 /// Find ambiguity among base classes.
3603 static void
detectAmbiguousBases(SmallVectorImpl<MSRTTIClass> & Classes)3604 detectAmbiguousBases(SmallVectorImpl<MSRTTIClass> &Classes) {
3605 llvm::SmallPtrSet<const CXXRecordDecl *, 8> VirtualBases;
3606 llvm::SmallPtrSet<const CXXRecordDecl *, 8> UniqueBases;
3607 llvm::SmallPtrSet<const CXXRecordDecl *, 8> AmbiguousBases;
3608 for (MSRTTIClass *Class = &Classes.front(); Class <= &Classes.back();) {
3609 if ((Class->Flags & MSRTTIClass::IsVirtual) &&
3610 !VirtualBases.insert(Class->RD).second) {
3611 Class = MSRTTIClass::getNextChild(Class);
3612 continue;
3613 }
3614 if (!UniqueBases.insert(Class->RD).second)
3615 AmbiguousBases.insert(Class->RD);
3616 Class++;
3617 }
3618 if (AmbiguousBases.empty())
3619 return;
3620 for (MSRTTIClass &Class : Classes)
3621 if (AmbiguousBases.count(Class.RD))
3622 Class.Flags |= MSRTTIClass::IsAmbiguous;
3623 }
3624
getClassHierarchyDescriptor()3625 llvm::GlobalVariable *MSRTTIBuilder::getClassHierarchyDescriptor() {
3626 SmallString<256> MangledName;
3627 {
3628 llvm::raw_svector_ostream Out(MangledName);
3629 ABI.getMangleContext().mangleCXXRTTIClassHierarchyDescriptor(RD, Out);
3630 }
3631
3632 // Check to see if we've already declared this ClassHierarchyDescriptor.
3633 if (auto CHD = Module.getNamedGlobal(MangledName))
3634 return CHD;
3635
3636 // Serialize the class hierarchy and initialize the CHD Fields.
3637 SmallVector<MSRTTIClass, 8> Classes;
3638 serializeClassHierarchy(Classes, RD);
3639 Classes.front().initialize(/*Parent=*/nullptr, /*Specifier=*/nullptr);
3640 detectAmbiguousBases(Classes);
3641 int Flags = 0;
3642 for (auto Class : Classes) {
3643 if (Class.RD->getNumBases() > 1)
3644 Flags |= HasBranchingHierarchy;
3645 // Note: cl.exe does not calculate "HasAmbiguousBases" correctly. We
3646 // believe the field isn't actually used.
3647 if (Class.Flags & MSRTTIClass::IsAmbiguous)
3648 Flags |= HasAmbiguousBases;
3649 }
3650 if ((Flags & HasBranchingHierarchy) && RD->getNumVBases() != 0)
3651 Flags |= HasVirtualBranchingHierarchy;
3652 // These gep indices are used to get the address of the first element of the
3653 // base class array.
3654 llvm::Value *GEPIndices[] = {llvm::ConstantInt::get(CGM.IntTy, 0),
3655 llvm::ConstantInt::get(CGM.IntTy, 0)};
3656
3657 // Forward-declare the class hierarchy descriptor
3658 auto Type = ABI.getClassHierarchyDescriptorType();
3659 auto CHD = new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage,
3660 /*Initializer=*/nullptr,
3661 MangledName);
3662 if (CHD->isWeakForLinker())
3663 CHD->setComdat(CGM.getModule().getOrInsertComdat(CHD->getName()));
3664
3665 auto *Bases = getBaseClassArray(Classes);
3666
3667 // Initialize the base class ClassHierarchyDescriptor.
3668 llvm::Constant *Fields[] = {
3669 llvm::ConstantInt::get(CGM.IntTy, 0), // reserved by the runtime
3670 llvm::ConstantInt::get(CGM.IntTy, Flags),
3671 llvm::ConstantInt::get(CGM.IntTy, Classes.size()),
3672 ABI.getImageRelativeConstant(llvm::ConstantExpr::getInBoundsGetElementPtr(
3673 Bases->getValueType(), Bases,
3674 llvm::ArrayRef<llvm::Value *>(GEPIndices))),
3675 };
3676 CHD->setInitializer(llvm::ConstantStruct::get(Type, Fields));
3677 return CHD;
3678 }
3679
3680 llvm::GlobalVariable *
getBaseClassArray(SmallVectorImpl<MSRTTIClass> & Classes)3681 MSRTTIBuilder::getBaseClassArray(SmallVectorImpl<MSRTTIClass> &Classes) {
3682 SmallString<256> MangledName;
3683 {
3684 llvm::raw_svector_ostream Out(MangledName);
3685 ABI.getMangleContext().mangleCXXRTTIBaseClassArray(RD, Out);
3686 }
3687
3688 // Forward-declare the base class array.
3689 // cl.exe pads the base class array with 1 (in 32 bit mode) or 4 (in 64 bit
3690 // mode) bytes of padding. We provide a pointer sized amount of padding by
3691 // adding +1 to Classes.size(). The sections have pointer alignment and are
3692 // marked pick-any so it shouldn't matter.
3693 llvm::Type *PtrType = ABI.getImageRelativeType(
3694 ABI.getBaseClassDescriptorType()->getPointerTo());
3695 auto *ArrType = llvm::ArrayType::get(PtrType, Classes.size() + 1);
3696 auto *BCA =
3697 new llvm::GlobalVariable(Module, ArrType,
3698 /*isConstant=*/true, Linkage,
3699 /*Initializer=*/nullptr, MangledName);
3700 if (BCA->isWeakForLinker())
3701 BCA->setComdat(CGM.getModule().getOrInsertComdat(BCA->getName()));
3702
3703 // Initialize the BaseClassArray.
3704 SmallVector<llvm::Constant *, 8> BaseClassArrayData;
3705 for (MSRTTIClass &Class : Classes)
3706 BaseClassArrayData.push_back(
3707 ABI.getImageRelativeConstant(getBaseClassDescriptor(Class)));
3708 BaseClassArrayData.push_back(llvm::Constant::getNullValue(PtrType));
3709 BCA->setInitializer(llvm::ConstantArray::get(ArrType, BaseClassArrayData));
3710 return BCA;
3711 }
3712
3713 llvm::GlobalVariable *
getBaseClassDescriptor(const MSRTTIClass & Class)3714 MSRTTIBuilder::getBaseClassDescriptor(const MSRTTIClass &Class) {
3715 // Compute the fields for the BaseClassDescriptor. They are computed up front
3716 // because they are mangled into the name of the object.
3717 uint32_t OffsetInVBTable = 0;
3718 int32_t VBPtrOffset = -1;
3719 if (Class.VirtualRoot) {
3720 auto &VTableContext = CGM.getMicrosoftVTableContext();
3721 OffsetInVBTable = VTableContext.getVBTableIndex(RD, Class.VirtualRoot) * 4;
3722 VBPtrOffset = Context.getASTRecordLayout(RD).getVBPtrOffset().getQuantity();
3723 }
3724
3725 SmallString<256> MangledName;
3726 {
3727 llvm::raw_svector_ostream Out(MangledName);
3728 ABI.getMangleContext().mangleCXXRTTIBaseClassDescriptor(
3729 Class.RD, Class.OffsetInVBase, VBPtrOffset, OffsetInVBTable,
3730 Class.Flags, Out);
3731 }
3732
3733 // Check to see if we've already declared this object.
3734 if (auto BCD = Module.getNamedGlobal(MangledName))
3735 return BCD;
3736
3737 // Forward-declare the base class descriptor.
3738 auto Type = ABI.getBaseClassDescriptorType();
3739 auto BCD =
3740 new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage,
3741 /*Initializer=*/nullptr, MangledName);
3742 if (BCD->isWeakForLinker())
3743 BCD->setComdat(CGM.getModule().getOrInsertComdat(BCD->getName()));
3744
3745 // Initialize the BaseClassDescriptor.
3746 llvm::Constant *Fields[] = {
3747 ABI.getImageRelativeConstant(
3748 ABI.getAddrOfRTTIDescriptor(Context.getTypeDeclType(Class.RD))),
3749 llvm::ConstantInt::get(CGM.IntTy, Class.NumBases),
3750 llvm::ConstantInt::get(CGM.IntTy, Class.OffsetInVBase),
3751 llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset),
3752 llvm::ConstantInt::get(CGM.IntTy, OffsetInVBTable),
3753 llvm::ConstantInt::get(CGM.IntTy, Class.Flags),
3754 ABI.getImageRelativeConstant(
3755 MSRTTIBuilder(ABI, Class.RD).getClassHierarchyDescriptor()),
3756 };
3757 BCD->setInitializer(llvm::ConstantStruct::get(Type, Fields));
3758 return BCD;
3759 }
3760
3761 llvm::GlobalVariable *
getCompleteObjectLocator(const VPtrInfo & Info)3762 MSRTTIBuilder::getCompleteObjectLocator(const VPtrInfo &Info) {
3763 SmallString<256> MangledName;
3764 {
3765 llvm::raw_svector_ostream Out(MangledName);
3766 ABI.getMangleContext().mangleCXXRTTICompleteObjectLocator(RD, Info.MangledPath, Out);
3767 }
3768
3769 // Check to see if we've already computed this complete object locator.
3770 if (auto COL = Module.getNamedGlobal(MangledName))
3771 return COL;
3772
3773 // Compute the fields of the complete object locator.
3774 int OffsetToTop = Info.FullOffsetInMDC.getQuantity();
3775 int VFPtrOffset = 0;
3776 // The offset includes the vtordisp if one exists.
3777 if (const CXXRecordDecl *VBase = Info.getVBaseWithVPtr())
3778 if (Context.getASTRecordLayout(RD)
3779 .getVBaseOffsetsMap()
3780 .find(VBase)
3781 ->second.hasVtorDisp())
3782 VFPtrOffset = Info.NonVirtualOffset.getQuantity() + 4;
3783
3784 // Forward-declare the complete object locator.
3785 llvm::StructType *Type = ABI.getCompleteObjectLocatorType();
3786 auto COL = new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage,
3787 /*Initializer=*/nullptr, MangledName);
3788
3789 // Initialize the CompleteObjectLocator.
3790 llvm::Constant *Fields[] = {
3791 llvm::ConstantInt::get(CGM.IntTy, ABI.isImageRelative()),
3792 llvm::ConstantInt::get(CGM.IntTy, OffsetToTop),
3793 llvm::ConstantInt::get(CGM.IntTy, VFPtrOffset),
3794 ABI.getImageRelativeConstant(
3795 CGM.GetAddrOfRTTIDescriptor(Context.getTypeDeclType(RD))),
3796 ABI.getImageRelativeConstant(getClassHierarchyDescriptor()),
3797 ABI.getImageRelativeConstant(COL),
3798 };
3799 llvm::ArrayRef<llvm::Constant *> FieldsRef(Fields);
3800 if (!ABI.isImageRelative())
3801 FieldsRef = FieldsRef.drop_back();
3802 COL->setInitializer(llvm::ConstantStruct::get(Type, FieldsRef));
3803 if (COL->isWeakForLinker())
3804 COL->setComdat(CGM.getModule().getOrInsertComdat(COL->getName()));
3805 return COL;
3806 }
3807
decomposeTypeForEH(ASTContext & Context,QualType T,bool & IsConst,bool & IsVolatile,bool & IsUnaligned)3808 static QualType decomposeTypeForEH(ASTContext &Context, QualType T,
3809 bool &IsConst, bool &IsVolatile,
3810 bool &IsUnaligned) {
3811 T = Context.getExceptionObjectType(T);
3812
3813 // C++14 [except.handle]p3:
3814 // A handler is a match for an exception object of type E if [...]
3815 // - the handler is of type cv T or const T& where T is a pointer type and
3816 // E is a pointer type that can be converted to T by [...]
3817 // - a qualification conversion
3818 IsConst = false;
3819 IsVolatile = false;
3820 IsUnaligned = false;
3821 QualType PointeeType = T->getPointeeType();
3822 if (!PointeeType.isNull()) {
3823 IsConst = PointeeType.isConstQualified();
3824 IsVolatile = PointeeType.isVolatileQualified();
3825 IsUnaligned = PointeeType.getQualifiers().hasUnaligned();
3826 }
3827
3828 // Member pointer types like "const int A::*" are represented by having RTTI
3829 // for "int A::*" and separately storing the const qualifier.
3830 if (const auto *MPTy = T->getAs<MemberPointerType>())
3831 T = Context.getMemberPointerType(PointeeType.getUnqualifiedType(),
3832 MPTy->getClass());
3833
3834 // Pointer types like "const int * const *" are represented by having RTTI
3835 // for "const int **" and separately storing the const qualifier.
3836 if (T->isPointerType())
3837 T = Context.getPointerType(PointeeType.getUnqualifiedType());
3838
3839 return T;
3840 }
3841
3842 CatchTypeInfo
getAddrOfCXXCatchHandlerType(QualType Type,QualType CatchHandlerType)3843 MicrosoftCXXABI::getAddrOfCXXCatchHandlerType(QualType Type,
3844 QualType CatchHandlerType) {
3845 // TypeDescriptors for exceptions never have qualified pointer types,
3846 // qualifiers are stored separately in order to support qualification
3847 // conversions.
3848 bool IsConst, IsVolatile, IsUnaligned;
3849 Type =
3850 decomposeTypeForEH(getContext(), Type, IsConst, IsVolatile, IsUnaligned);
3851
3852 bool IsReference = CatchHandlerType->isReferenceType();
3853
3854 uint32_t Flags = 0;
3855 if (IsConst)
3856 Flags |= 1;
3857 if (IsVolatile)
3858 Flags |= 2;
3859 if (IsUnaligned)
3860 Flags |= 4;
3861 if (IsReference)
3862 Flags |= 8;
3863
3864 return CatchTypeInfo{getAddrOfRTTIDescriptor(Type)->stripPointerCasts(),
3865 Flags};
3866 }
3867
3868 /// Gets a TypeDescriptor. Returns a llvm::Constant * rather than a
3869 /// llvm::GlobalVariable * because different type descriptors have different
3870 /// types, and need to be abstracted. They are abstracting by casting the
3871 /// address to an Int8PtrTy.
getAddrOfRTTIDescriptor(QualType Type)3872 llvm::Constant *MicrosoftCXXABI::getAddrOfRTTIDescriptor(QualType Type) {
3873 SmallString<256> MangledName;
3874 {
3875 llvm::raw_svector_ostream Out(MangledName);
3876 getMangleContext().mangleCXXRTTI(Type, Out);
3877 }
3878
3879 // Check to see if we've already declared this TypeDescriptor.
3880 if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName))
3881 return llvm::ConstantExpr::getBitCast(GV, CGM.Int8PtrTy);
3882
3883 // Note for the future: If we would ever like to do deferred emission of
3884 // RTTI, check if emitting vtables opportunistically need any adjustment.
3885
3886 // Compute the fields for the TypeDescriptor.
3887 SmallString<256> TypeInfoString;
3888 {
3889 llvm::raw_svector_ostream Out(TypeInfoString);
3890 getMangleContext().mangleCXXRTTIName(Type, Out);
3891 }
3892
3893 // Declare and initialize the TypeDescriptor.
3894 llvm::Constant *Fields[] = {
3895 getTypeInfoVTable(CGM), // VFPtr
3896 llvm::ConstantPointerNull::get(CGM.Int8PtrTy), // Runtime data
3897 llvm::ConstantDataArray::getString(CGM.getLLVMContext(), TypeInfoString)};
3898 llvm::StructType *TypeDescriptorType =
3899 getTypeDescriptorType(TypeInfoString);
3900 auto *Var = new llvm::GlobalVariable(
3901 CGM.getModule(), TypeDescriptorType, /*isConstant=*/false,
3902 getLinkageForRTTI(Type),
3903 llvm::ConstantStruct::get(TypeDescriptorType, Fields),
3904 MangledName);
3905 if (Var->isWeakForLinker())
3906 Var->setComdat(CGM.getModule().getOrInsertComdat(Var->getName()));
3907 return llvm::ConstantExpr::getBitCast(Var, CGM.Int8PtrTy);
3908 }
3909
3910 /// Gets or a creates a Microsoft CompleteObjectLocator.
3911 llvm::GlobalVariable *
getMSCompleteObjectLocator(const CXXRecordDecl * RD,const VPtrInfo & Info)3912 MicrosoftCXXABI::getMSCompleteObjectLocator(const CXXRecordDecl *RD,
3913 const VPtrInfo &Info) {
3914 return MSRTTIBuilder(*this, RD).getCompleteObjectLocator(Info);
3915 }
3916
emitCXXStructor(GlobalDecl GD)3917 void MicrosoftCXXABI::emitCXXStructor(GlobalDecl GD) {
3918 if (auto *ctor = dyn_cast<CXXConstructorDecl>(GD.getDecl())) {
3919 // There are no constructor variants, always emit the complete destructor.
3920 llvm::Function *Fn =
3921 CGM.codegenCXXStructor(GD.getWithCtorType(Ctor_Complete));
3922 CGM.maybeSetTrivialComdat(*ctor, *Fn);
3923 return;
3924 }
3925
3926 auto *dtor = cast<CXXDestructorDecl>(GD.getDecl());
3927
3928 // Emit the base destructor if the base and complete (vbase) destructors are
3929 // equivalent. This effectively implements -mconstructor-aliases as part of
3930 // the ABI.
3931 if (GD.getDtorType() == Dtor_Complete &&
3932 dtor->getParent()->getNumVBases() == 0)
3933 GD = GD.getWithDtorType(Dtor_Base);
3934
3935 // The base destructor is equivalent to the base destructor of its
3936 // base class if there is exactly one non-virtual base class with a
3937 // non-trivial destructor, there are no fields with a non-trivial
3938 // destructor, and the body of the destructor is trivial.
3939 if (GD.getDtorType() == Dtor_Base && !CGM.TryEmitBaseDestructorAsAlias(dtor))
3940 return;
3941
3942 llvm::Function *Fn = CGM.codegenCXXStructor(GD);
3943 if (Fn->isWeakForLinker())
3944 Fn->setComdat(CGM.getModule().getOrInsertComdat(Fn->getName()));
3945 }
3946
3947 llvm::Function *
getAddrOfCXXCtorClosure(const CXXConstructorDecl * CD,CXXCtorType CT)3948 MicrosoftCXXABI::getAddrOfCXXCtorClosure(const CXXConstructorDecl *CD,
3949 CXXCtorType CT) {
3950 assert(CT == Ctor_CopyingClosure || CT == Ctor_DefaultClosure);
3951
3952 // Calculate the mangled name.
3953 SmallString<256> ThunkName;
3954 llvm::raw_svector_ostream Out(ThunkName);
3955 getMangleContext().mangleName(GlobalDecl(CD, CT), Out);
3956
3957 // If the thunk has been generated previously, just return it.
3958 if (llvm::GlobalValue *GV = CGM.getModule().getNamedValue(ThunkName))
3959 return cast<llvm::Function>(GV);
3960
3961 // Create the llvm::Function.
3962 const CGFunctionInfo &FnInfo = CGM.getTypes().arrangeMSCtorClosure(CD, CT);
3963 llvm::FunctionType *ThunkTy = CGM.getTypes().GetFunctionType(FnInfo);
3964 const CXXRecordDecl *RD = CD->getParent();
3965 QualType RecordTy = getContext().getRecordType(RD);
3966 llvm::Function *ThunkFn = llvm::Function::Create(
3967 ThunkTy, getLinkageForRTTI(RecordTy), ThunkName.str(), &CGM.getModule());
3968 ThunkFn->setCallingConv(static_cast<llvm::CallingConv::ID>(
3969 FnInfo.getEffectiveCallingConvention()));
3970 if (ThunkFn->isWeakForLinker())
3971 ThunkFn->setComdat(CGM.getModule().getOrInsertComdat(ThunkFn->getName()));
3972 bool IsCopy = CT == Ctor_CopyingClosure;
3973
3974 // Start codegen.
3975 CodeGenFunction CGF(CGM);
3976 CGF.CurGD = GlobalDecl(CD, Ctor_Complete);
3977
3978 // Build FunctionArgs.
3979 FunctionArgList FunctionArgs;
3980
3981 // A constructor always starts with a 'this' pointer as its first argument.
3982 buildThisParam(CGF, FunctionArgs);
3983
3984 // Following the 'this' pointer is a reference to the source object that we
3985 // are copying from.
3986 ImplicitParamDecl SrcParam(
3987 getContext(), /*DC=*/nullptr, SourceLocation(),
3988 &getContext().Idents.get("src"),
3989 getContext().getLValueReferenceType(RecordTy,
3990 /*SpelledAsLValue=*/true),
3991 ImplicitParamDecl::Other);
3992 if (IsCopy)
3993 FunctionArgs.push_back(&SrcParam);
3994
3995 // Constructors for classes which utilize virtual bases have an additional
3996 // parameter which indicates whether or not it is being delegated to by a more
3997 // derived constructor.
3998 ImplicitParamDecl IsMostDerived(getContext(), /*DC=*/nullptr,
3999 SourceLocation(),
4000 &getContext().Idents.get("is_most_derived"),
4001 getContext().IntTy, ImplicitParamDecl::Other);
4002 // Only add the parameter to the list if the class has virtual bases.
4003 if (RD->getNumVBases() > 0)
4004 FunctionArgs.push_back(&IsMostDerived);
4005
4006 // Start defining the function.
4007 auto NL = ApplyDebugLocation::CreateEmpty(CGF);
4008 CGF.StartFunction(GlobalDecl(), FnInfo.getReturnType(), ThunkFn, FnInfo,
4009 FunctionArgs, CD->getLocation(), SourceLocation());
4010 // Create a scope with an artificial location for the body of this function.
4011 auto AL = ApplyDebugLocation::CreateArtificial(CGF);
4012 setCXXABIThisValue(CGF, loadIncomingCXXThis(CGF));
4013 llvm::Value *This = getThisValue(CGF);
4014
4015 llvm::Value *SrcVal =
4016 IsCopy ? CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(&SrcParam), "src")
4017 : nullptr;
4018
4019 CallArgList Args;
4020
4021 // Push the this ptr.
4022 Args.add(RValue::get(This), CD->getThisType());
4023
4024 // Push the src ptr.
4025 if (SrcVal)
4026 Args.add(RValue::get(SrcVal), SrcParam.getType());
4027
4028 // Add the rest of the default arguments.
4029 SmallVector<const Stmt *, 4> ArgVec;
4030 ArrayRef<ParmVarDecl *> params = CD->parameters().drop_front(IsCopy ? 1 : 0);
4031 for (const ParmVarDecl *PD : params) {
4032 assert(PD->hasDefaultArg() && "ctor closure lacks default args");
4033 ArgVec.push_back(PD->getDefaultArg());
4034 }
4035
4036 CodeGenFunction::RunCleanupsScope Cleanups(CGF);
4037
4038 const auto *FPT = CD->getType()->castAs<FunctionProtoType>();
4039 CGF.EmitCallArgs(Args, FPT, llvm::makeArrayRef(ArgVec), CD, IsCopy ? 1 : 0);
4040
4041 // Insert any ABI-specific implicit constructor arguments.
4042 AddedStructorArgCounts ExtraArgs =
4043 addImplicitConstructorArgs(CGF, CD, Ctor_Complete,
4044 /*ForVirtualBase=*/false,
4045 /*Delegating=*/false, Args);
4046 // Call the destructor with our arguments.
4047 llvm::Constant *CalleePtr =
4048 CGM.getAddrOfCXXStructor(GlobalDecl(CD, Ctor_Complete));
4049 CGCallee Callee =
4050 CGCallee::forDirect(CalleePtr, GlobalDecl(CD, Ctor_Complete));
4051 const CGFunctionInfo &CalleeInfo = CGM.getTypes().arrangeCXXConstructorCall(
4052 Args, CD, Ctor_Complete, ExtraArgs.Prefix, ExtraArgs.Suffix);
4053 CGF.EmitCall(CalleeInfo, Callee, ReturnValueSlot(), Args);
4054
4055 Cleanups.ForceCleanup();
4056
4057 // Emit the ret instruction, remove any temporary instructions created for the
4058 // aid of CodeGen.
4059 CGF.FinishFunction(SourceLocation());
4060
4061 return ThunkFn;
4062 }
4063
getCatchableType(QualType T,uint32_t NVOffset,int32_t VBPtrOffset,uint32_t VBIndex)4064 llvm::Constant *MicrosoftCXXABI::getCatchableType(QualType T,
4065 uint32_t NVOffset,
4066 int32_t VBPtrOffset,
4067 uint32_t VBIndex) {
4068 assert(!T->isReferenceType());
4069
4070 CXXRecordDecl *RD = T->getAsCXXRecordDecl();
4071 const CXXConstructorDecl *CD =
4072 RD ? CGM.getContext().getCopyConstructorForExceptionObject(RD) : nullptr;
4073 CXXCtorType CT = Ctor_Complete;
4074 if (CD)
4075 if (!hasDefaultCXXMethodCC(getContext(), CD) || CD->getNumParams() != 1)
4076 CT = Ctor_CopyingClosure;
4077
4078 uint32_t Size = getContext().getTypeSizeInChars(T).getQuantity();
4079 SmallString<256> MangledName;
4080 {
4081 llvm::raw_svector_ostream Out(MangledName);
4082 getMangleContext().mangleCXXCatchableType(T, CD, CT, Size, NVOffset,
4083 VBPtrOffset, VBIndex, Out);
4084 }
4085 if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName))
4086 return getImageRelativeConstant(GV);
4087
4088 // The TypeDescriptor is used by the runtime to determine if a catch handler
4089 // is appropriate for the exception object.
4090 llvm::Constant *TD = getImageRelativeConstant(getAddrOfRTTIDescriptor(T));
4091
4092 // The runtime is responsible for calling the copy constructor if the
4093 // exception is caught by value.
4094 llvm::Constant *CopyCtor;
4095 if (CD) {
4096 if (CT == Ctor_CopyingClosure)
4097 CopyCtor = getAddrOfCXXCtorClosure(CD, Ctor_CopyingClosure);
4098 else
4099 CopyCtor = CGM.getAddrOfCXXStructor(GlobalDecl(CD, Ctor_Complete));
4100
4101 CopyCtor = llvm::ConstantExpr::getBitCast(CopyCtor, CGM.Int8PtrTy);
4102 } else {
4103 CopyCtor = llvm::Constant::getNullValue(CGM.Int8PtrTy);
4104 }
4105 CopyCtor = getImageRelativeConstant(CopyCtor);
4106
4107 bool IsScalar = !RD;
4108 bool HasVirtualBases = false;
4109 bool IsStdBadAlloc = false; // std::bad_alloc is special for some reason.
4110 QualType PointeeType = T;
4111 if (T->isPointerType())
4112 PointeeType = T->getPointeeType();
4113 if (const CXXRecordDecl *RD = PointeeType->getAsCXXRecordDecl()) {
4114 HasVirtualBases = RD->getNumVBases() > 0;
4115 if (IdentifierInfo *II = RD->getIdentifier())
4116 IsStdBadAlloc = II->isStr("bad_alloc") && RD->isInStdNamespace();
4117 }
4118
4119 // Encode the relevant CatchableType properties into the Flags bitfield.
4120 // FIXME: Figure out how bits 2 or 8 can get set.
4121 uint32_t Flags = 0;
4122 if (IsScalar)
4123 Flags |= 1;
4124 if (HasVirtualBases)
4125 Flags |= 4;
4126 if (IsStdBadAlloc)
4127 Flags |= 16;
4128
4129 llvm::Constant *Fields[] = {
4130 llvm::ConstantInt::get(CGM.IntTy, Flags), // Flags
4131 TD, // TypeDescriptor
4132 llvm::ConstantInt::get(CGM.IntTy, NVOffset), // NonVirtualAdjustment
4133 llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset), // OffsetToVBPtr
4134 llvm::ConstantInt::get(CGM.IntTy, VBIndex), // VBTableIndex
4135 llvm::ConstantInt::get(CGM.IntTy, Size), // Size
4136 CopyCtor // CopyCtor
4137 };
4138 llvm::StructType *CTType = getCatchableTypeType();
4139 auto *GV = new llvm::GlobalVariable(
4140 CGM.getModule(), CTType, /*isConstant=*/true, getLinkageForRTTI(T),
4141 llvm::ConstantStruct::get(CTType, Fields), MangledName);
4142 GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
4143 GV->setSection(".xdata");
4144 if (GV->isWeakForLinker())
4145 GV->setComdat(CGM.getModule().getOrInsertComdat(GV->getName()));
4146 return getImageRelativeConstant(GV);
4147 }
4148
getCatchableTypeArray(QualType T)4149 llvm::GlobalVariable *MicrosoftCXXABI::getCatchableTypeArray(QualType T) {
4150 assert(!T->isReferenceType());
4151
4152 // See if we've already generated a CatchableTypeArray for this type before.
4153 llvm::GlobalVariable *&CTA = CatchableTypeArrays[T];
4154 if (CTA)
4155 return CTA;
4156
4157 // Ensure that we don't have duplicate entries in our CatchableTypeArray by
4158 // using a SmallSetVector. Duplicates may arise due to virtual bases
4159 // occurring more than once in the hierarchy.
4160 llvm::SmallSetVector<llvm::Constant *, 2> CatchableTypes;
4161
4162 // C++14 [except.handle]p3:
4163 // A handler is a match for an exception object of type E if [...]
4164 // - the handler is of type cv T or cv T& and T is an unambiguous public
4165 // base class of E, or
4166 // - the handler is of type cv T or const T& where T is a pointer type and
4167 // E is a pointer type that can be converted to T by [...]
4168 // - a standard pointer conversion (4.10) not involving conversions to
4169 // pointers to private or protected or ambiguous classes
4170 const CXXRecordDecl *MostDerivedClass = nullptr;
4171 bool IsPointer = T->isPointerType();
4172 if (IsPointer)
4173 MostDerivedClass = T->getPointeeType()->getAsCXXRecordDecl();
4174 else
4175 MostDerivedClass = T->getAsCXXRecordDecl();
4176
4177 // Collect all the unambiguous public bases of the MostDerivedClass.
4178 if (MostDerivedClass) {
4179 const ASTContext &Context = getContext();
4180 const ASTRecordLayout &MostDerivedLayout =
4181 Context.getASTRecordLayout(MostDerivedClass);
4182 MicrosoftVTableContext &VTableContext = CGM.getMicrosoftVTableContext();
4183 SmallVector<MSRTTIClass, 8> Classes;
4184 serializeClassHierarchy(Classes, MostDerivedClass);
4185 Classes.front().initialize(/*Parent=*/nullptr, /*Specifier=*/nullptr);
4186 detectAmbiguousBases(Classes);
4187 for (const MSRTTIClass &Class : Classes) {
4188 // Skip any ambiguous or private bases.
4189 if (Class.Flags &
4190 (MSRTTIClass::IsPrivateOnPath | MSRTTIClass::IsAmbiguous))
4191 continue;
4192 // Write down how to convert from a derived pointer to a base pointer.
4193 uint32_t OffsetInVBTable = 0;
4194 int32_t VBPtrOffset = -1;
4195 if (Class.VirtualRoot) {
4196 OffsetInVBTable =
4197 VTableContext.getVBTableIndex(MostDerivedClass, Class.VirtualRoot)*4;
4198 VBPtrOffset = MostDerivedLayout.getVBPtrOffset().getQuantity();
4199 }
4200
4201 // Turn our record back into a pointer if the exception object is a
4202 // pointer.
4203 QualType RTTITy = QualType(Class.RD->getTypeForDecl(), 0);
4204 if (IsPointer)
4205 RTTITy = Context.getPointerType(RTTITy);
4206 CatchableTypes.insert(getCatchableType(RTTITy, Class.OffsetInVBase,
4207 VBPtrOffset, OffsetInVBTable));
4208 }
4209 }
4210
4211 // C++14 [except.handle]p3:
4212 // A handler is a match for an exception object of type E if
4213 // - The handler is of type cv T or cv T& and E and T are the same type
4214 // (ignoring the top-level cv-qualifiers)
4215 CatchableTypes.insert(getCatchableType(T));
4216
4217 // C++14 [except.handle]p3:
4218 // A handler is a match for an exception object of type E if
4219 // - the handler is of type cv T or const T& where T is a pointer type and
4220 // E is a pointer type that can be converted to T by [...]
4221 // - a standard pointer conversion (4.10) not involving conversions to
4222 // pointers to private or protected or ambiguous classes
4223 //
4224 // C++14 [conv.ptr]p2:
4225 // A prvalue of type "pointer to cv T," where T is an object type, can be
4226 // converted to a prvalue of type "pointer to cv void".
4227 if (IsPointer && T->getPointeeType()->isObjectType())
4228 CatchableTypes.insert(getCatchableType(getContext().VoidPtrTy));
4229
4230 // C++14 [except.handle]p3:
4231 // A handler is a match for an exception object of type E if [...]
4232 // - the handler is of type cv T or const T& where T is a pointer or
4233 // pointer to member type and E is std::nullptr_t.
4234 //
4235 // We cannot possibly list all possible pointer types here, making this
4236 // implementation incompatible with the standard. However, MSVC includes an
4237 // entry for pointer-to-void in this case. Let's do the same.
4238 if (T->isNullPtrType())
4239 CatchableTypes.insert(getCatchableType(getContext().VoidPtrTy));
4240
4241 uint32_t NumEntries = CatchableTypes.size();
4242 llvm::Type *CTType =
4243 getImageRelativeType(getCatchableTypeType()->getPointerTo());
4244 llvm::ArrayType *AT = llvm::ArrayType::get(CTType, NumEntries);
4245 llvm::StructType *CTAType = getCatchableTypeArrayType(NumEntries);
4246 llvm::Constant *Fields[] = {
4247 llvm::ConstantInt::get(CGM.IntTy, NumEntries), // NumEntries
4248 llvm::ConstantArray::get(
4249 AT, llvm::makeArrayRef(CatchableTypes.begin(),
4250 CatchableTypes.end())) // CatchableTypes
4251 };
4252 SmallString<256> MangledName;
4253 {
4254 llvm::raw_svector_ostream Out(MangledName);
4255 getMangleContext().mangleCXXCatchableTypeArray(T, NumEntries, Out);
4256 }
4257 CTA = new llvm::GlobalVariable(
4258 CGM.getModule(), CTAType, /*isConstant=*/true, getLinkageForRTTI(T),
4259 llvm::ConstantStruct::get(CTAType, Fields), MangledName);
4260 CTA->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
4261 CTA->setSection(".xdata");
4262 if (CTA->isWeakForLinker())
4263 CTA->setComdat(CGM.getModule().getOrInsertComdat(CTA->getName()));
4264 return CTA;
4265 }
4266
getThrowInfo(QualType T)4267 llvm::GlobalVariable *MicrosoftCXXABI::getThrowInfo(QualType T) {
4268 bool IsConst, IsVolatile, IsUnaligned;
4269 T = decomposeTypeForEH(getContext(), T, IsConst, IsVolatile, IsUnaligned);
4270
4271 // The CatchableTypeArray enumerates the various (CV-unqualified) types that
4272 // the exception object may be caught as.
4273 llvm::GlobalVariable *CTA = getCatchableTypeArray(T);
4274 // The first field in a CatchableTypeArray is the number of CatchableTypes.
4275 // This is used as a component of the mangled name which means that we need to
4276 // know what it is in order to see if we have previously generated the
4277 // ThrowInfo.
4278 uint32_t NumEntries =
4279 cast<llvm::ConstantInt>(CTA->getInitializer()->getAggregateElement(0U))
4280 ->getLimitedValue();
4281
4282 SmallString<256> MangledName;
4283 {
4284 llvm::raw_svector_ostream Out(MangledName);
4285 getMangleContext().mangleCXXThrowInfo(T, IsConst, IsVolatile, IsUnaligned,
4286 NumEntries, Out);
4287 }
4288
4289 // Reuse a previously generated ThrowInfo if we have generated an appropriate
4290 // one before.
4291 if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName))
4292 return GV;
4293
4294 // The RTTI TypeDescriptor uses an unqualified type but catch clauses must
4295 // be at least as CV qualified. Encode this requirement into the Flags
4296 // bitfield.
4297 uint32_t Flags = 0;
4298 if (IsConst)
4299 Flags |= 1;
4300 if (IsVolatile)
4301 Flags |= 2;
4302 if (IsUnaligned)
4303 Flags |= 4;
4304
4305 // The cleanup-function (a destructor) must be called when the exception
4306 // object's lifetime ends.
4307 llvm::Constant *CleanupFn = llvm::Constant::getNullValue(CGM.Int8PtrTy);
4308 if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
4309 if (CXXDestructorDecl *DtorD = RD->getDestructor())
4310 if (!DtorD->isTrivial())
4311 CleanupFn = llvm::ConstantExpr::getBitCast(
4312 CGM.getAddrOfCXXStructor(GlobalDecl(DtorD, Dtor_Complete)),
4313 CGM.Int8PtrTy);
4314 // This is unused as far as we can tell, initialize it to null.
4315 llvm::Constant *ForwardCompat =
4316 getImageRelativeConstant(llvm::Constant::getNullValue(CGM.Int8PtrTy));
4317 llvm::Constant *PointerToCatchableTypes = getImageRelativeConstant(
4318 llvm::ConstantExpr::getBitCast(CTA, CGM.Int8PtrTy));
4319 llvm::StructType *TIType = getThrowInfoType();
4320 llvm::Constant *Fields[] = {
4321 llvm::ConstantInt::get(CGM.IntTy, Flags), // Flags
4322 getImageRelativeConstant(CleanupFn), // CleanupFn
4323 ForwardCompat, // ForwardCompat
4324 PointerToCatchableTypes // CatchableTypeArray
4325 };
4326 auto *GV = new llvm::GlobalVariable(
4327 CGM.getModule(), TIType, /*isConstant=*/true, getLinkageForRTTI(T),
4328 llvm::ConstantStruct::get(TIType, Fields), StringRef(MangledName));
4329 GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
4330 GV->setSection(".xdata");
4331 if (GV->isWeakForLinker())
4332 GV->setComdat(CGM.getModule().getOrInsertComdat(GV->getName()));
4333 return GV;
4334 }
4335
emitThrow(CodeGenFunction & CGF,const CXXThrowExpr * E)4336 void MicrosoftCXXABI::emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) {
4337 const Expr *SubExpr = E->getSubExpr();
4338 QualType ThrowType = SubExpr->getType();
4339 // The exception object lives on the stack and it's address is passed to the
4340 // runtime function.
4341 Address AI = CGF.CreateMemTemp(ThrowType);
4342 CGF.EmitAnyExprToMem(SubExpr, AI, ThrowType.getQualifiers(),
4343 /*IsInit=*/true);
4344
4345 // The so-called ThrowInfo is used to describe how the exception object may be
4346 // caught.
4347 llvm::GlobalVariable *TI = getThrowInfo(ThrowType);
4348
4349 // Call into the runtime to throw the exception.
4350 llvm::Value *Args[] = {
4351 CGF.Builder.CreateBitCast(AI.getPointer(), CGM.Int8PtrTy),
4352 TI
4353 };
4354 CGF.EmitNoreturnRuntimeCallOrInvoke(getThrowFn(), Args);
4355 }
4356
4357 std::pair<llvm::Value *, const CXXRecordDecl *>
LoadVTablePtr(CodeGenFunction & CGF,Address This,const CXXRecordDecl * RD)4358 MicrosoftCXXABI::LoadVTablePtr(CodeGenFunction &CGF, Address This,
4359 const CXXRecordDecl *RD) {
4360 std::tie(This, std::ignore, RD) =
4361 performBaseAdjustment(CGF, This, QualType(RD->getTypeForDecl(), 0));
4362 return {CGF.GetVTablePtr(This, CGM.Int8PtrTy, RD), RD};
4363 }
4364
isPermittedToBeHomogeneousAggregate(const CXXRecordDecl * CXXRD) const4365 bool MicrosoftCXXABI::isPermittedToBeHomogeneousAggregate(
4366 const CXXRecordDecl *CXXRD) const {
4367 // MSVC Windows on Arm64 considers a type not HFA if it is not an
4368 // aggregate according to the C++14 spec. This is not consistent with the
4369 // AAPCS64, but is defacto spec on that platform.
4370 return !CGM.getTarget().getTriple().isAArch64() ||
4371 isTrivialForAArch64MSVC(CXXRD);
4372 }
4373