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 "ABIInfo.h"
17 #include "CGCXXABI.h"
18 #include "CGCleanup.h"
19 #include "CGVTables.h"
20 #include "CodeGenModule.h"
21 #include "CodeGenTypes.h"
22 #include "TargetInfo.h"
23 #include "clang/AST/Attr.h"
24 #include "clang/AST/CXXInheritance.h"
25 #include "clang/AST/Decl.h"
26 #include "clang/AST/DeclCXX.h"
27 #include "clang/AST/StmtCXX.h"
28 #include "clang/AST/VTableBuilder.h"
29 #include "clang/CodeGen/ConstantInitBuilder.h"
30 #include "llvm/ADT/StringExtras.h"
31 #include "llvm/ADT/StringSet.h"
32 #include "llvm/IR/Intrinsics.h"
33
34 using namespace clang;
35 using namespace CodeGen;
36
37 namespace {
38
39 /// Holds all the vbtable globals for a given class.
40 struct VBTableGlobals {
41 const VPtrInfoVector *VBTables;
42 SmallVector<llvm::GlobalVariable *, 2> Globals;
43 };
44
45 class MicrosoftCXXABI : public CGCXXABI {
46 public:
MicrosoftCXXABI(CodeGenModule & CGM)47 MicrosoftCXXABI(CodeGenModule &CGM)
48 : CGCXXABI(CGM), BaseClassDescriptorType(nullptr),
49 ClassHierarchyDescriptorType(nullptr),
50 CompleteObjectLocatorType(nullptr), CatchableTypeType(nullptr),
51 ThrowInfoType(nullptr) {
52 assert(!(CGM.getLangOpts().isExplicitDefaultVisibilityExportMapping() ||
53 CGM.getLangOpts().isAllDefaultVisibilityExportMapping()) &&
54 "visibility export mapping option unimplemented in this ABI");
55 }
56
57 bool HasThisReturn(GlobalDecl GD) const override;
58 bool hasMostDerivedReturn(GlobalDecl GD) const override;
59
60 bool classifyReturnType(CGFunctionInfo &FI) const override;
61
62 RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const override;
63
isSRetParameterAfterThis() const64 bool isSRetParameterAfterThis() const override { return true; }
65
isThisCompleteObject(GlobalDecl GD) const66 bool isThisCompleteObject(GlobalDecl GD) const override {
67 // The Microsoft ABI doesn't use separate complete-object vs.
68 // base-object variants of constructors, but it does of destructors.
69 if (isa<CXXDestructorDecl>(GD.getDecl())) {
70 switch (GD.getDtorType()) {
71 case Dtor_Complete:
72 case Dtor_Deleting:
73 return true;
74
75 case Dtor_Base:
76 return false;
77
78 case Dtor_Comdat: llvm_unreachable("emitting dtor comdat as function?");
79 }
80 llvm_unreachable("bad dtor kind");
81 }
82
83 // No other kinds.
84 return false;
85 }
86
getSrcArgforCopyCtor(const CXXConstructorDecl * CD,FunctionArgList & Args) const87 size_t getSrcArgforCopyCtor(const CXXConstructorDecl *CD,
88 FunctionArgList &Args) const override {
89 assert(Args.size() >= 2 &&
90 "expected the arglist to have at least two args!");
91 // The 'most_derived' parameter goes second if the ctor is variadic and
92 // has v-bases.
93 if (CD->getParent()->getNumVBases() > 0 &&
94 CD->getType()->castAs<FunctionProtoType>()->isVariadic())
95 return 2;
96 return 1;
97 }
98
getVBPtrOffsets(const CXXRecordDecl * RD)99 std::vector<CharUnits> getVBPtrOffsets(const CXXRecordDecl *RD) override {
100 std::vector<CharUnits> VBPtrOffsets;
101 const ASTContext &Context = getContext();
102 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
103
104 const VBTableGlobals &VBGlobals = enumerateVBTables(RD);
105 for (const std::unique_ptr<VPtrInfo> &VBT : *VBGlobals.VBTables) {
106 const ASTRecordLayout &SubobjectLayout =
107 Context.getASTRecordLayout(VBT->IntroducingObject);
108 CharUnits Offs = VBT->NonVirtualOffset;
109 Offs += SubobjectLayout.getVBPtrOffset();
110 if (VBT->getVBaseWithVPtr())
111 Offs += Layout.getVBaseClassOffset(VBT->getVBaseWithVPtr());
112 VBPtrOffsets.push_back(Offs);
113 }
114 llvm::array_pod_sort(VBPtrOffsets.begin(), VBPtrOffsets.end());
115 return VBPtrOffsets;
116 }
117
GetPureVirtualCallName()118 StringRef GetPureVirtualCallName() override { return "_purecall"; }
GetDeletedVirtualCallName()119 StringRef GetDeletedVirtualCallName() override { return "_purecall"; }
120
121 void emitVirtualObjectDelete(CodeGenFunction &CGF, const CXXDeleteExpr *DE,
122 Address Ptr, QualType ElementType,
123 const CXXDestructorDecl *Dtor) override;
124
125 void emitRethrow(CodeGenFunction &CGF, bool isNoReturn) override;
126 void emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) override;
127
128 void emitBeginCatch(CodeGenFunction &CGF, const CXXCatchStmt *C) override;
129
130 llvm::GlobalVariable *getMSCompleteObjectLocator(const CXXRecordDecl *RD,
131 const VPtrInfo &Info);
132
133 llvm::Constant *getAddrOfRTTIDescriptor(QualType Ty) override;
134 CatchTypeInfo
135 getAddrOfCXXCatchHandlerType(QualType Ty, QualType CatchHandlerType) override;
136
137 /// MSVC needs an extra flag to indicate a catchall.
getCatchAllTypeInfo()138 CatchTypeInfo getCatchAllTypeInfo() override {
139 // For -EHa catch(...) must handle HW exception
140 // Adjective = HT_IsStdDotDot (0x40), only catch C++ exceptions
141 if (getContext().getLangOpts().EHAsynch)
142 return CatchTypeInfo{nullptr, 0};
143 else
144 return CatchTypeInfo{nullptr, 0x40};
145 }
146
147 bool shouldTypeidBeNullChecked(bool IsDeref, QualType SrcRecordTy) override;
148 void EmitBadTypeidCall(CodeGenFunction &CGF) override;
149 llvm::Value *EmitTypeid(CodeGenFunction &CGF, QualType SrcRecordTy,
150 Address ThisPtr,
151 llvm::Type *StdTypeInfoPtrTy) override;
152
153 bool shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,
154 QualType SrcRecordTy) override;
155
shouldEmitExactDynamicCast(QualType DestRecordTy)156 bool shouldEmitExactDynamicCast(QualType DestRecordTy) override {
157 // TODO: Add support for exact dynamic_casts.
158 return false;
159 }
emitExactDynamicCast(CodeGenFunction & CGF,Address Value,QualType SrcRecordTy,QualType DestTy,QualType DestRecordTy,llvm::BasicBlock * CastSuccess,llvm::BasicBlock * CastFail)160 llvm::Value *emitExactDynamicCast(CodeGenFunction &CGF, Address Value,
161 QualType SrcRecordTy, QualType DestTy,
162 QualType DestRecordTy,
163 llvm::BasicBlock *CastSuccess,
164 llvm::BasicBlock *CastFail) override {
165 llvm_unreachable("unsupported");
166 }
167
168 llvm::Value *emitDynamicCastCall(CodeGenFunction &CGF, Address Value,
169 QualType SrcRecordTy, QualType DestTy,
170 QualType DestRecordTy,
171 llvm::BasicBlock *CastEnd) override;
172
173 llvm::Value *emitDynamicCastToVoid(CodeGenFunction &CGF, Address Value,
174 QualType SrcRecordTy) override;
175
176 bool EmitBadCastCall(CodeGenFunction &CGF) override;
canSpeculativelyEmitVTable(const CXXRecordDecl * RD) const177 bool canSpeculativelyEmitVTable(const CXXRecordDecl *RD) const override {
178 return false;
179 }
180
181 llvm::Value *
182 GetVirtualBaseClassOffset(CodeGenFunction &CGF, Address This,
183 const CXXRecordDecl *ClassDecl,
184 const CXXRecordDecl *BaseClassDecl) override;
185
186 llvm::BasicBlock *
187 EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
188 const CXXRecordDecl *RD) override;
189
190 llvm::BasicBlock *
191 EmitDtorCompleteObjectHandler(CodeGenFunction &CGF);
192
193 void initializeHiddenVirtualInheritanceMembers(CodeGenFunction &CGF,
194 const CXXRecordDecl *RD) override;
195
196 void EmitCXXConstructors(const CXXConstructorDecl *D) override;
197
198 // Background on MSVC destructors
199 // ==============================
200 //
201 // Both Itanium and MSVC ABIs have destructor variants. The variant names
202 // roughly correspond in the following way:
203 // Itanium Microsoft
204 // Base -> no name, just ~Class
205 // Complete -> vbase destructor
206 // Deleting -> scalar deleting destructor
207 // vector deleting destructor
208 //
209 // The base and complete destructors are the same as in Itanium, although the
210 // complete destructor does not accept a VTT parameter when there are virtual
211 // bases. A separate mechanism involving vtordisps is used to ensure that
212 // virtual methods of destroyed subobjects are not called.
213 //
214 // The deleting destructors accept an i32 bitfield as a second parameter. Bit
215 // 1 indicates if the memory should be deleted. Bit 2 indicates if the this
216 // pointer points to an array. The scalar deleting destructor assumes that
217 // bit 2 is zero, and therefore does not contain a loop.
218 //
219 // For virtual destructors, only one entry is reserved in the vftable, and it
220 // always points to the vector deleting destructor. The vector deleting
221 // destructor is the most general, so it can be used to destroy objects in
222 // place, delete single heap objects, or delete arrays.
223 //
224 // A TU defining a non-inline destructor is only guaranteed to emit a base
225 // destructor, and all of the other variants are emitted on an as-needed basis
226 // in COMDATs. Because a non-base destructor can be emitted in a TU that
227 // lacks a definition for the destructor, non-base destructors must always
228 // delegate to or alias the base destructor.
229
230 AddedStructorArgCounts
231 buildStructorSignature(GlobalDecl GD,
232 SmallVectorImpl<CanQualType> &ArgTys) override;
233
234 /// Non-base dtors should be emitted as delegating thunks in this ABI.
useThunkForDtorVariant(const CXXDestructorDecl * Dtor,CXXDtorType DT) const235 bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor,
236 CXXDtorType DT) const override {
237 return DT != Dtor_Base;
238 }
239
240 void setCXXDestructorDLLStorage(llvm::GlobalValue *GV,
241 const CXXDestructorDecl *Dtor,
242 CXXDtorType DT) const override;
243
244 llvm::GlobalValue::LinkageTypes
245 getCXXDestructorLinkage(GVALinkage Linkage, const CXXDestructorDecl *Dtor,
246 CXXDtorType DT) const override;
247
248 void EmitCXXDestructors(const CXXDestructorDecl *D) override;
249
getThisArgumentTypeForMethod(GlobalDecl GD)250 const CXXRecordDecl *getThisArgumentTypeForMethod(GlobalDecl GD) override {
251 auto *MD = cast<CXXMethodDecl>(GD.getDecl());
252
253 if (MD->isVirtual()) {
254 GlobalDecl LookupGD = GD;
255 if (const auto *DD = dyn_cast<CXXDestructorDecl>(MD)) {
256 // Complete dtors take a pointer to the complete object,
257 // thus don't need adjustment.
258 if (GD.getDtorType() == Dtor_Complete)
259 return MD->getParent();
260
261 // There's only Dtor_Deleting in vftable but it shares the this
262 // adjustment with the base one, so look up the deleting one instead.
263 LookupGD = GlobalDecl(DD, Dtor_Deleting);
264 }
265 MethodVFTableLocation ML =
266 CGM.getMicrosoftVTableContext().getMethodVFTableLocation(LookupGD);
267
268 // The vbases might be ordered differently in the final overrider object
269 // and the complete object, so the "this" argument may sometimes point to
270 // memory that has no particular type (e.g. past the complete object).
271 // In this case, we just use a generic pointer type.
272 // FIXME: might want to have a more precise type in the non-virtual
273 // multiple inheritance case.
274 if (ML.VBase || !ML.VFPtrOffset.isZero())
275 return nullptr;
276 }
277 return MD->getParent();
278 }
279
280 Address
281 adjustThisArgumentForVirtualFunctionCall(CodeGenFunction &CGF, GlobalDecl GD,
282 Address This,
283 bool VirtualCall) override;
284
285 void addImplicitStructorParams(CodeGenFunction &CGF, QualType &ResTy,
286 FunctionArgList &Params) override;
287
288 void EmitInstanceFunctionProlog(CodeGenFunction &CGF) override;
289
290 AddedStructorArgs getImplicitConstructorArgs(CodeGenFunction &CGF,
291 const CXXConstructorDecl *D,
292 CXXCtorType Type,
293 bool ForVirtualBase,
294 bool Delegating) override;
295
296 llvm::Value *getCXXDestructorImplicitParam(CodeGenFunction &CGF,
297 const CXXDestructorDecl *DD,
298 CXXDtorType Type,
299 bool ForVirtualBase,
300 bool Delegating) override;
301
302 void EmitDestructorCall(CodeGenFunction &CGF, const CXXDestructorDecl *DD,
303 CXXDtorType Type, bool ForVirtualBase,
304 bool Delegating, Address This,
305 QualType ThisTy) override;
306
307 void emitVTableTypeMetadata(const VPtrInfo &Info, const CXXRecordDecl *RD,
308 llvm::GlobalVariable *VTable);
309
310 void emitVTableDefinitions(CodeGenVTables &CGVT,
311 const CXXRecordDecl *RD) override;
312
313 bool isVirtualOffsetNeededForVTableField(CodeGenFunction &CGF,
314 CodeGenFunction::VPtr Vptr) override;
315
316 /// Don't initialize vptrs if dynamic class
317 /// is marked with the 'novtable' attribute.
doStructorsInitializeVPtrs(const CXXRecordDecl * VTableClass)318 bool doStructorsInitializeVPtrs(const CXXRecordDecl *VTableClass) override {
319 return !VTableClass->hasAttr<MSNoVTableAttr>();
320 }
321
322 llvm::Constant *
323 getVTableAddressPoint(BaseSubobject Base,
324 const CXXRecordDecl *VTableClass) override;
325
326 llvm::Value *getVTableAddressPointInStructor(
327 CodeGenFunction &CGF, const CXXRecordDecl *VTableClass,
328 BaseSubobject Base, const CXXRecordDecl *NearestVBase) override;
329
330 llvm::Constant *
331 getVTableAddressPointForConstExpr(BaseSubobject Base,
332 const CXXRecordDecl *VTableClass) override;
333
334 llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD,
335 CharUnits VPtrOffset) override;
336
337 CGCallee getVirtualFunctionPointer(CodeGenFunction &CGF, GlobalDecl GD,
338 Address This, llvm::Type *Ty,
339 SourceLocation Loc) override;
340
341 llvm::Value *EmitVirtualDestructorCall(CodeGenFunction &CGF,
342 const CXXDestructorDecl *Dtor,
343 CXXDtorType DtorType, Address This,
344 DeleteOrMemberCallExpr E) override;
345
adjustCallArgsForDestructorThunk(CodeGenFunction & CGF,GlobalDecl GD,CallArgList & CallArgs)346 void adjustCallArgsForDestructorThunk(CodeGenFunction &CGF, GlobalDecl GD,
347 CallArgList &CallArgs) override {
348 assert(GD.getDtorType() == Dtor_Deleting &&
349 "Only deleting destructor thunks are available in this ABI");
350 CallArgs.add(RValue::get(getStructorImplicitParamValue(CGF)),
351 getContext().IntTy);
352 }
353
354 void emitVirtualInheritanceTables(const CXXRecordDecl *RD) override;
355
356 llvm::GlobalVariable *
357 getAddrOfVBTable(const VPtrInfo &VBT, const CXXRecordDecl *RD,
358 llvm::GlobalVariable::LinkageTypes Linkage);
359
360 llvm::GlobalVariable *
getAddrOfVirtualDisplacementMap(const CXXRecordDecl * SrcRD,const CXXRecordDecl * DstRD)361 getAddrOfVirtualDisplacementMap(const CXXRecordDecl *SrcRD,
362 const CXXRecordDecl *DstRD) {
363 SmallString<256> OutName;
364 llvm::raw_svector_ostream Out(OutName);
365 getMangleContext().mangleCXXVirtualDisplacementMap(SrcRD, DstRD, Out);
366 StringRef MangledName = OutName.str();
367
368 if (auto *VDispMap = CGM.getModule().getNamedGlobal(MangledName))
369 return VDispMap;
370
371 MicrosoftVTableContext &VTContext = CGM.getMicrosoftVTableContext();
372 unsigned NumEntries = 1 + SrcRD->getNumVBases();
373 SmallVector<llvm::Constant *, 4> Map(NumEntries,
374 llvm::UndefValue::get(CGM.IntTy));
375 Map[0] = llvm::ConstantInt::get(CGM.IntTy, 0);
376 bool AnyDifferent = false;
377 for (const auto &I : SrcRD->vbases()) {
378 const CXXRecordDecl *VBase = I.getType()->getAsCXXRecordDecl();
379 if (!DstRD->isVirtuallyDerivedFrom(VBase))
380 continue;
381
382 unsigned SrcVBIndex = VTContext.getVBTableIndex(SrcRD, VBase);
383 unsigned DstVBIndex = VTContext.getVBTableIndex(DstRD, VBase);
384 Map[SrcVBIndex] = llvm::ConstantInt::get(CGM.IntTy, DstVBIndex * 4);
385 AnyDifferent |= SrcVBIndex != DstVBIndex;
386 }
387 // This map would be useless, don't use it.
388 if (!AnyDifferent)
389 return nullptr;
390
391 llvm::ArrayType *VDispMapTy = llvm::ArrayType::get(CGM.IntTy, Map.size());
392 llvm::Constant *Init = llvm::ConstantArray::get(VDispMapTy, Map);
393 llvm::GlobalValue::LinkageTypes Linkage =
394 SrcRD->isExternallyVisible() && DstRD->isExternallyVisible()
395 ? llvm::GlobalValue::LinkOnceODRLinkage
396 : llvm::GlobalValue::InternalLinkage;
397 auto *VDispMap = new llvm::GlobalVariable(
398 CGM.getModule(), VDispMapTy, /*isConstant=*/true, Linkage,
399 /*Initializer=*/Init, MangledName);
400 return VDispMap;
401 }
402
403 void emitVBTableDefinition(const VPtrInfo &VBT, const CXXRecordDecl *RD,
404 llvm::GlobalVariable *GV) const;
405
setThunkLinkage(llvm::Function * Thunk,bool ForVTable,GlobalDecl GD,bool ReturnAdjustment)406 void setThunkLinkage(llvm::Function *Thunk, bool ForVTable,
407 GlobalDecl GD, bool ReturnAdjustment) override {
408 GVALinkage Linkage =
409 getContext().GetGVALinkageForFunction(cast<FunctionDecl>(GD.getDecl()));
410
411 if (Linkage == GVA_Internal)
412 Thunk->setLinkage(llvm::GlobalValue::InternalLinkage);
413 else if (ReturnAdjustment)
414 Thunk->setLinkage(llvm::GlobalValue::WeakODRLinkage);
415 else
416 Thunk->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage);
417 }
418
exportThunk()419 bool exportThunk() override { return false; }
420
421 llvm::Value *performThisAdjustment(CodeGenFunction &CGF, Address This,
422 const ThisAdjustment &TA) override;
423
424 llvm::Value *performReturnAdjustment(CodeGenFunction &CGF, Address Ret,
425 const ReturnAdjustment &RA) override;
426
427 void EmitThreadLocalInitFuncs(
428 CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals,
429 ArrayRef<llvm::Function *> CXXThreadLocalInits,
430 ArrayRef<const VarDecl *> CXXThreadLocalInitVars) override;
431
usesThreadWrapperFunction(const VarDecl * VD) const432 bool usesThreadWrapperFunction(const VarDecl *VD) const override {
433 return getContext().getLangOpts().isCompatibleWithMSVC(
434 LangOptions::MSVC2019_5) &&
435 (!isEmittedWithConstantInitializer(VD) || mayNeedDestruction(VD));
436 }
437 LValue EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF, const VarDecl *VD,
438 QualType LValType) override;
439
440 void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
441 llvm::GlobalVariable *DeclPtr,
442 bool PerformInit) override;
443 void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,
444 llvm::FunctionCallee Dtor,
445 llvm::Constant *Addr) override;
446
447 // ==== Notes on array cookies =========
448 //
449 // MSVC seems to only use cookies when the class has a destructor; a
450 // two-argument usual array deallocation function isn't sufficient.
451 //
452 // For example, this code prints "100" and "1":
453 // struct A {
454 // char x;
455 // void *operator new[](size_t sz) {
456 // printf("%u\n", sz);
457 // return malloc(sz);
458 // }
459 // void operator delete[](void *p, size_t sz) {
460 // printf("%u\n", sz);
461 // free(p);
462 // }
463 // };
464 // int main() {
465 // A *p = new A[100];
466 // delete[] p;
467 // }
468 // Whereas it prints "104" and "104" if you give A a destructor.
469
470 bool requiresArrayCookie(const CXXDeleteExpr *expr,
471 QualType elementType) override;
472 bool requiresArrayCookie(const CXXNewExpr *expr) override;
473 CharUnits getArrayCookieSizeImpl(QualType type) override;
474 Address InitializeArrayCookie(CodeGenFunction &CGF,
475 Address NewPtr,
476 llvm::Value *NumElements,
477 const CXXNewExpr *expr,
478 QualType ElementType) override;
479 llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF,
480 Address allocPtr,
481 CharUnits cookieSize) override;
482
483 friend struct MSRTTIBuilder;
484
isImageRelative() const485 bool isImageRelative() const {
486 return CGM.getTarget().getPointerWidth(LangAS::Default) == 64;
487 }
488
489 // 5 routines for constructing the llvm types for MS RTTI structs.
getTypeDescriptorType(StringRef TypeInfoString)490 llvm::StructType *getTypeDescriptorType(StringRef TypeInfoString) {
491 llvm::SmallString<32> TDTypeName("rtti.TypeDescriptor");
492 TDTypeName += llvm::utostr(TypeInfoString.size());
493 llvm::StructType *&TypeDescriptorType =
494 TypeDescriptorTypeMap[TypeInfoString.size()];
495 if (TypeDescriptorType)
496 return TypeDescriptorType;
497 llvm::Type *FieldTypes[] = {
498 CGM.Int8PtrPtrTy,
499 CGM.Int8PtrTy,
500 llvm::ArrayType::get(CGM.Int8Ty, TypeInfoString.size() + 1)};
501 TypeDescriptorType =
502 llvm::StructType::create(CGM.getLLVMContext(), FieldTypes, TDTypeName);
503 return TypeDescriptorType;
504 }
505
getImageRelativeType(llvm::Type * PtrType)506 llvm::Type *getImageRelativeType(llvm::Type *PtrType) {
507 if (!isImageRelative())
508 return PtrType;
509 return CGM.IntTy;
510 }
511
getBaseClassDescriptorType()512 llvm::StructType *getBaseClassDescriptorType() {
513 if (BaseClassDescriptorType)
514 return BaseClassDescriptorType;
515 llvm::Type *FieldTypes[] = {
516 getImageRelativeType(CGM.Int8PtrTy),
517 CGM.IntTy,
518 CGM.IntTy,
519 CGM.IntTy,
520 CGM.IntTy,
521 CGM.IntTy,
522 getImageRelativeType(getClassHierarchyDescriptorType()->getPointerTo()),
523 };
524 BaseClassDescriptorType = llvm::StructType::create(
525 CGM.getLLVMContext(), FieldTypes, "rtti.BaseClassDescriptor");
526 return BaseClassDescriptorType;
527 }
528
getClassHierarchyDescriptorType()529 llvm::StructType *getClassHierarchyDescriptorType() {
530 if (ClassHierarchyDescriptorType)
531 return ClassHierarchyDescriptorType;
532 // Forward-declare RTTIClassHierarchyDescriptor to break a cycle.
533 ClassHierarchyDescriptorType = llvm::StructType::create(
534 CGM.getLLVMContext(), "rtti.ClassHierarchyDescriptor");
535 llvm::Type *FieldTypes[] = {
536 CGM.IntTy,
537 CGM.IntTy,
538 CGM.IntTy,
539 getImageRelativeType(
540 getBaseClassDescriptorType()->getPointerTo()->getPointerTo()),
541 };
542 ClassHierarchyDescriptorType->setBody(FieldTypes);
543 return ClassHierarchyDescriptorType;
544 }
545
getCompleteObjectLocatorType()546 llvm::StructType *getCompleteObjectLocatorType() {
547 if (CompleteObjectLocatorType)
548 return CompleteObjectLocatorType;
549 CompleteObjectLocatorType = llvm::StructType::create(
550 CGM.getLLVMContext(), "rtti.CompleteObjectLocator");
551 llvm::Type *FieldTypes[] = {
552 CGM.IntTy,
553 CGM.IntTy,
554 CGM.IntTy,
555 getImageRelativeType(CGM.Int8PtrTy),
556 getImageRelativeType(getClassHierarchyDescriptorType()->getPointerTo()),
557 getImageRelativeType(CompleteObjectLocatorType),
558 };
559 llvm::ArrayRef<llvm::Type *> FieldTypesRef(FieldTypes);
560 if (!isImageRelative())
561 FieldTypesRef = FieldTypesRef.drop_back();
562 CompleteObjectLocatorType->setBody(FieldTypesRef);
563 return CompleteObjectLocatorType;
564 }
565
getImageBase()566 llvm::GlobalVariable *getImageBase() {
567 StringRef Name = "__ImageBase";
568 if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(Name))
569 return GV;
570
571 auto *GV = new llvm::GlobalVariable(CGM.getModule(), CGM.Int8Ty,
572 /*isConstant=*/true,
573 llvm::GlobalValue::ExternalLinkage,
574 /*Initializer=*/nullptr, Name);
575 CGM.setDSOLocal(GV);
576 return GV;
577 }
578
getImageRelativeConstant(llvm::Constant * PtrVal)579 llvm::Constant *getImageRelativeConstant(llvm::Constant *PtrVal) {
580 if (!isImageRelative())
581 return PtrVal;
582
583 if (PtrVal->isNullValue())
584 return llvm::Constant::getNullValue(CGM.IntTy);
585
586 llvm::Constant *ImageBaseAsInt =
587 llvm::ConstantExpr::getPtrToInt(getImageBase(), CGM.IntPtrTy);
588 llvm::Constant *PtrValAsInt =
589 llvm::ConstantExpr::getPtrToInt(PtrVal, CGM.IntPtrTy);
590 llvm::Constant *Diff =
591 llvm::ConstantExpr::getSub(PtrValAsInt, ImageBaseAsInt,
592 /*HasNUW=*/true, /*HasNSW=*/true);
593 return llvm::ConstantExpr::getTrunc(Diff, CGM.IntTy);
594 }
595
596 private:
getMangleContext()597 MicrosoftMangleContext &getMangleContext() {
598 return cast<MicrosoftMangleContext>(CodeGen::CGCXXABI::getMangleContext());
599 }
600
getZeroInt()601 llvm::Constant *getZeroInt() {
602 return llvm::ConstantInt::get(CGM.IntTy, 0);
603 }
604
getAllOnesInt()605 llvm::Constant *getAllOnesInt() {
606 return llvm::Constant::getAllOnesValue(CGM.IntTy);
607 }
608
609 CharUnits getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) override;
610
611 void
612 GetNullMemberPointerFields(const MemberPointerType *MPT,
613 llvm::SmallVectorImpl<llvm::Constant *> &fields);
614
615 /// Shared code for virtual base adjustment. Returns the offset from
616 /// the vbptr to the virtual base. Optionally returns the address of the
617 /// vbptr itself.
618 llvm::Value *GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,
619 Address Base,
620 llvm::Value *VBPtrOffset,
621 llvm::Value *VBTableOffset,
622 llvm::Value **VBPtr = nullptr);
623
GetVBaseOffsetFromVBPtr(CodeGenFunction & CGF,Address Base,int32_t VBPtrOffset,int32_t VBTableOffset,llvm::Value ** VBPtr=nullptr)624 llvm::Value *GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,
625 Address Base,
626 int32_t VBPtrOffset,
627 int32_t VBTableOffset,
628 llvm::Value **VBPtr = nullptr) {
629 assert(VBTableOffset % 4 == 0 && "should be byte offset into table of i32s");
630 llvm::Value *VBPOffset = llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset),
631 *VBTOffset = llvm::ConstantInt::get(CGM.IntTy, VBTableOffset);
632 return GetVBaseOffsetFromVBPtr(CGF, Base, VBPOffset, VBTOffset, VBPtr);
633 }
634
635 std::tuple<Address, llvm::Value *, const CXXRecordDecl *>
636 performBaseAdjustment(CodeGenFunction &CGF, Address Value,
637 QualType SrcRecordTy);
638
639 /// Performs a full virtual base adjustment. Used to dereference
640 /// pointers to members of virtual bases.
641 llvm::Value *AdjustVirtualBase(CodeGenFunction &CGF, const Expr *E,
642 const CXXRecordDecl *RD, Address Base,
643 llvm::Value *VirtualBaseAdjustmentOffset,
644 llvm::Value *VBPtrOffset /* optional */);
645
646 /// Emits a full member pointer with the fields common to data and
647 /// function member pointers.
648 llvm::Constant *EmitFullMemberPointer(llvm::Constant *FirstField,
649 bool IsMemberFunction,
650 const CXXRecordDecl *RD,
651 CharUnits NonVirtualBaseAdjustment,
652 unsigned VBTableIndex);
653
654 bool MemberPointerConstantIsNull(const MemberPointerType *MPT,
655 llvm::Constant *MP);
656
657 /// - Initialize all vbptrs of 'this' with RD as the complete type.
658 void EmitVBPtrStores(CodeGenFunction &CGF, const CXXRecordDecl *RD);
659
660 /// Caching wrapper around VBTableBuilder::enumerateVBTables().
661 const VBTableGlobals &enumerateVBTables(const CXXRecordDecl *RD);
662
663 /// Generate a thunk for calling a virtual member function MD.
664 llvm::Function *EmitVirtualMemPtrThunk(const CXXMethodDecl *MD,
665 const MethodVFTableLocation &ML);
666
667 llvm::Constant *EmitMemberDataPointer(const CXXRecordDecl *RD,
668 CharUnits offset);
669
670 public:
671 llvm::Type *ConvertMemberPointerType(const MemberPointerType *MPT) override;
672
673 bool isZeroInitializable(const MemberPointerType *MPT) override;
674
isMemberPointerConvertible(const MemberPointerType * MPT) const675 bool isMemberPointerConvertible(const MemberPointerType *MPT) const override {
676 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
677 return RD->hasAttr<MSInheritanceAttr>();
678 }
679
680 llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT) override;
681
682 llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,
683 CharUnits offset) override;
684 llvm::Constant *EmitMemberFunctionPointer(const CXXMethodDecl *MD) override;
685 llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT) override;
686
687 llvm::Value *EmitMemberPointerComparison(CodeGenFunction &CGF,
688 llvm::Value *L,
689 llvm::Value *R,
690 const MemberPointerType *MPT,
691 bool Inequality) override;
692
693 llvm::Value *EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
694 llvm::Value *MemPtr,
695 const MemberPointerType *MPT) override;
696
697 llvm::Value *
698 EmitMemberDataPointerAddress(CodeGenFunction &CGF, const Expr *E,
699 Address Base, llvm::Value *MemPtr,
700 const MemberPointerType *MPT) override;
701
702 llvm::Value *EmitNonNullMemberPointerConversion(
703 const MemberPointerType *SrcTy, const MemberPointerType *DstTy,
704 CastKind CK, CastExpr::path_const_iterator PathBegin,
705 CastExpr::path_const_iterator PathEnd, llvm::Value *Src,
706 CGBuilderTy &Builder);
707
708 llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,
709 const CastExpr *E,
710 llvm::Value *Src) override;
711
712 llvm::Constant *EmitMemberPointerConversion(const CastExpr *E,
713 llvm::Constant *Src) override;
714
715 llvm::Constant *EmitMemberPointerConversion(
716 const MemberPointerType *SrcTy, const MemberPointerType *DstTy,
717 CastKind CK, CastExpr::path_const_iterator PathBegin,
718 CastExpr::path_const_iterator PathEnd, llvm::Constant *Src);
719
720 CGCallee
721 EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, const Expr *E,
722 Address This, llvm::Value *&ThisPtrForCall,
723 llvm::Value *MemPtr,
724 const MemberPointerType *MPT) override;
725
726 void emitCXXStructor(GlobalDecl GD) override;
727
getCatchableTypeType()728 llvm::StructType *getCatchableTypeType() {
729 if (CatchableTypeType)
730 return CatchableTypeType;
731 llvm::Type *FieldTypes[] = {
732 CGM.IntTy, // Flags
733 getImageRelativeType(CGM.Int8PtrTy), // TypeDescriptor
734 CGM.IntTy, // NonVirtualAdjustment
735 CGM.IntTy, // OffsetToVBPtr
736 CGM.IntTy, // VBTableIndex
737 CGM.IntTy, // Size
738 getImageRelativeType(CGM.Int8PtrTy) // CopyCtor
739 };
740 CatchableTypeType = llvm::StructType::create(
741 CGM.getLLVMContext(), FieldTypes, "eh.CatchableType");
742 return CatchableTypeType;
743 }
744
getCatchableTypeArrayType(uint32_t NumEntries)745 llvm::StructType *getCatchableTypeArrayType(uint32_t NumEntries) {
746 llvm::StructType *&CatchableTypeArrayType =
747 CatchableTypeArrayTypeMap[NumEntries];
748 if (CatchableTypeArrayType)
749 return CatchableTypeArrayType;
750
751 llvm::SmallString<23> CTATypeName("eh.CatchableTypeArray.");
752 CTATypeName += llvm::utostr(NumEntries);
753 llvm::Type *CTType =
754 getImageRelativeType(getCatchableTypeType()->getPointerTo());
755 llvm::Type *FieldTypes[] = {
756 CGM.IntTy, // NumEntries
757 llvm::ArrayType::get(CTType, NumEntries) // CatchableTypes
758 };
759 CatchableTypeArrayType =
760 llvm::StructType::create(CGM.getLLVMContext(), FieldTypes, CTATypeName);
761 return CatchableTypeArrayType;
762 }
763
getThrowInfoType()764 llvm::StructType *getThrowInfoType() {
765 if (ThrowInfoType)
766 return ThrowInfoType;
767 llvm::Type *FieldTypes[] = {
768 CGM.IntTy, // Flags
769 getImageRelativeType(CGM.Int8PtrTy), // CleanupFn
770 getImageRelativeType(CGM.Int8PtrTy), // ForwardCompat
771 getImageRelativeType(CGM.Int8PtrTy) // CatchableTypeArray
772 };
773 ThrowInfoType = llvm::StructType::create(CGM.getLLVMContext(), FieldTypes,
774 "eh.ThrowInfo");
775 return ThrowInfoType;
776 }
777
getThrowFn()778 llvm::FunctionCallee getThrowFn() {
779 // _CxxThrowException is passed an exception object and a ThrowInfo object
780 // which describes the exception.
781 llvm::Type *Args[] = {CGM.Int8PtrTy, getThrowInfoType()->getPointerTo()};
782 llvm::FunctionType *FTy =
783 llvm::FunctionType::get(CGM.VoidTy, Args, /*isVarArg=*/false);
784 llvm::FunctionCallee Throw =
785 CGM.CreateRuntimeFunction(FTy, "_CxxThrowException");
786 // _CxxThrowException is stdcall on 32-bit x86 platforms.
787 if (CGM.getTarget().getTriple().getArch() == llvm::Triple::x86) {
788 if (auto *Fn = dyn_cast<llvm::Function>(Throw.getCallee()))
789 Fn->setCallingConv(llvm::CallingConv::X86_StdCall);
790 }
791 return Throw;
792 }
793
794 llvm::Function *getAddrOfCXXCtorClosure(const CXXConstructorDecl *CD,
795 CXXCtorType CT);
796
797 llvm::Constant *getCatchableType(QualType T,
798 uint32_t NVOffset = 0,
799 int32_t VBPtrOffset = -1,
800 uint32_t VBIndex = 0);
801
802 llvm::GlobalVariable *getCatchableTypeArray(QualType T);
803
804 llvm::GlobalVariable *getThrowInfo(QualType T) override;
805
806 std::pair<llvm::Value *, const CXXRecordDecl *>
807 LoadVTablePtr(CodeGenFunction &CGF, Address This,
808 const CXXRecordDecl *RD) override;
809
810 bool
811 isPermittedToBeHomogeneousAggregate(const CXXRecordDecl *RD) const override;
812
813 private:
814 typedef std::pair<const CXXRecordDecl *, CharUnits> VFTableIdTy;
815 typedef llvm::DenseMap<VFTableIdTy, llvm::GlobalVariable *> VTablesMapTy;
816 typedef llvm::DenseMap<VFTableIdTy, llvm::GlobalValue *> VFTablesMapTy;
817 /// All the vftables that have been referenced.
818 VFTablesMapTy VFTablesMap;
819 VTablesMapTy VTablesMap;
820
821 /// This set holds the record decls we've deferred vtable emission for.
822 llvm::SmallPtrSet<const CXXRecordDecl *, 4> DeferredVFTables;
823
824
825 /// All the vbtables which have been referenced.
826 llvm::DenseMap<const CXXRecordDecl *, VBTableGlobals> VBTablesMap;
827
828 /// Info on the global variable used to guard initialization of static locals.
829 /// The BitIndex field is only used for externally invisible declarations.
830 struct GuardInfo {
831 GuardInfo() = default;
832 llvm::GlobalVariable *Guard = nullptr;
833 unsigned BitIndex = 0;
834 };
835
836 /// Map from DeclContext to the current guard variable. We assume that the
837 /// AST is visited in source code order.
838 llvm::DenseMap<const DeclContext *, GuardInfo> GuardVariableMap;
839 llvm::DenseMap<const DeclContext *, GuardInfo> ThreadLocalGuardVariableMap;
840 llvm::DenseMap<const DeclContext *, unsigned> ThreadSafeGuardNumMap;
841
842 llvm::DenseMap<size_t, llvm::StructType *> TypeDescriptorTypeMap;
843 llvm::StructType *BaseClassDescriptorType;
844 llvm::StructType *ClassHierarchyDescriptorType;
845 llvm::StructType *CompleteObjectLocatorType;
846
847 llvm::DenseMap<QualType, llvm::GlobalVariable *> CatchableTypeArrays;
848
849 llvm::StructType *CatchableTypeType;
850 llvm::DenseMap<uint32_t, llvm::StructType *> CatchableTypeArrayTypeMap;
851 llvm::StructType *ThrowInfoType;
852 };
853
854 }
855
856 CGCXXABI::RecordArgABI
getRecordArgABI(const CXXRecordDecl * RD) const857 MicrosoftCXXABI::getRecordArgABI(const CXXRecordDecl *RD) const {
858 // Use the default C calling convention rules for things that can be passed in
859 // registers, i.e. non-trivially copyable records or records marked with
860 // [[trivial_abi]].
861 if (RD->canPassInRegisters())
862 return RAA_Default;
863
864 switch (CGM.getTarget().getTriple().getArch()) {
865 default:
866 // FIXME: Implement for other architectures.
867 return RAA_Indirect;
868
869 case llvm::Triple::thumb:
870 // Pass things indirectly for now because it is simple.
871 // FIXME: This is incompatible with MSVC for arguments with a dtor and no
872 // copy ctor.
873 return RAA_Indirect;
874
875 case llvm::Triple::x86: {
876 // If the argument has *required* alignment greater than four bytes, pass
877 // it indirectly. Prior to MSVC version 19.14, passing overaligned
878 // arguments was not supported and resulted in a compiler error. In 19.14
879 // and later versions, such arguments are now passed indirectly.
880 TypeInfo Info = getContext().getTypeInfo(RD->getTypeForDecl());
881 if (Info.isAlignRequired() && Info.Align > 4)
882 return RAA_Indirect;
883
884 // If C++ prohibits us from making a copy, construct the arguments directly
885 // into argument memory.
886 return RAA_DirectInMemory;
887 }
888
889 case llvm::Triple::x86_64:
890 case llvm::Triple::aarch64:
891 return RAA_Indirect;
892 }
893
894 llvm_unreachable("invalid enum");
895 }
896
emitVirtualObjectDelete(CodeGenFunction & CGF,const CXXDeleteExpr * DE,Address Ptr,QualType ElementType,const CXXDestructorDecl * Dtor)897 void MicrosoftCXXABI::emitVirtualObjectDelete(CodeGenFunction &CGF,
898 const CXXDeleteExpr *DE,
899 Address Ptr,
900 QualType ElementType,
901 const CXXDestructorDecl *Dtor) {
902 // FIXME: Provide a source location here even though there's no
903 // CXXMemberCallExpr for dtor call.
904 bool UseGlobalDelete = DE->isGlobalDelete();
905 CXXDtorType DtorType = UseGlobalDelete ? Dtor_Complete : Dtor_Deleting;
906 llvm::Value *MDThis = EmitVirtualDestructorCall(CGF, Dtor, DtorType, Ptr, DE);
907 if (UseGlobalDelete)
908 CGF.EmitDeleteCall(DE->getOperatorDelete(), MDThis, ElementType);
909 }
910
emitRethrow(CodeGenFunction & CGF,bool isNoReturn)911 void MicrosoftCXXABI::emitRethrow(CodeGenFunction &CGF, bool isNoReturn) {
912 llvm::Value *Args[] = {
913 llvm::ConstantPointerNull::get(CGM.Int8PtrTy),
914 llvm::ConstantPointerNull::get(getThrowInfoType()->getPointerTo())};
915 llvm::FunctionCallee Fn = getThrowFn();
916 if (isNoReturn)
917 CGF.EmitNoreturnRuntimeCallOrInvoke(Fn, Args);
918 else
919 CGF.EmitRuntimeCallOrInvoke(Fn, Args);
920 }
921
emitBeginCatch(CodeGenFunction & CGF,const CXXCatchStmt * S)922 void MicrosoftCXXABI::emitBeginCatch(CodeGenFunction &CGF,
923 const CXXCatchStmt *S) {
924 // In the MS ABI, the runtime handles the copy, and the catch handler is
925 // responsible for destruction.
926 VarDecl *CatchParam = S->getExceptionDecl();
927 llvm::BasicBlock *CatchPadBB = CGF.Builder.GetInsertBlock();
928 llvm::CatchPadInst *CPI =
929 cast<llvm::CatchPadInst>(CatchPadBB->getFirstNonPHI());
930 CGF.CurrentFuncletPad = CPI;
931
932 // If this is a catch-all or the catch parameter is unnamed, we don't need to
933 // emit an alloca to the object.
934 if (!CatchParam || !CatchParam->getDeclName()) {
935 CGF.EHStack.pushCleanup<CatchRetScope>(NormalCleanup, CPI);
936 return;
937 }
938
939 CodeGenFunction::AutoVarEmission var = CGF.EmitAutoVarAlloca(*CatchParam);
940 CPI->setArgOperand(2, var.getObjectAddress(CGF).getPointer());
941 CGF.EHStack.pushCleanup<CatchRetScope>(NormalCleanup, CPI);
942 CGF.EmitAutoVarCleanups(var);
943 }
944
945 /// We need to perform a generic polymorphic operation (like a typeid
946 /// or a cast), which requires an object with a vfptr. Adjust the
947 /// address to point to an object with a vfptr.
948 std::tuple<Address, llvm::Value *, const CXXRecordDecl *>
performBaseAdjustment(CodeGenFunction & CGF,Address Value,QualType SrcRecordTy)949 MicrosoftCXXABI::performBaseAdjustment(CodeGenFunction &CGF, Address Value,
950 QualType SrcRecordTy) {
951 Value = Value.withElementType(CGF.Int8Ty);
952 const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();
953 const ASTContext &Context = getContext();
954
955 // If the class itself has a vfptr, great. This check implicitly
956 // covers non-virtual base subobjects: a class with its own virtual
957 // functions would be a candidate to be a primary base.
958 if (Context.getASTRecordLayout(SrcDecl).hasExtendableVFPtr())
959 return std::make_tuple(Value, llvm::ConstantInt::get(CGF.Int32Ty, 0),
960 SrcDecl);
961
962 // Okay, one of the vbases must have a vfptr, or else this isn't
963 // actually a polymorphic class.
964 const CXXRecordDecl *PolymorphicBase = nullptr;
965 for (auto &Base : SrcDecl->vbases()) {
966 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
967 if (Context.getASTRecordLayout(BaseDecl).hasExtendableVFPtr()) {
968 PolymorphicBase = BaseDecl;
969 break;
970 }
971 }
972 assert(PolymorphicBase && "polymorphic class has no apparent vfptr?");
973
974 llvm::Value *Offset =
975 GetVirtualBaseClassOffset(CGF, Value, SrcDecl, PolymorphicBase);
976 llvm::Value *Ptr = CGF.Builder.CreateInBoundsGEP(
977 Value.getElementType(), Value.getPointer(), Offset);
978 CharUnits VBaseAlign =
979 CGF.CGM.getVBaseAlignment(Value.getAlignment(), SrcDecl, PolymorphicBase);
980 return std::make_tuple(Address(Ptr, CGF.Int8Ty, VBaseAlign), Offset,
981 PolymorphicBase);
982 }
983
shouldTypeidBeNullChecked(bool IsDeref,QualType SrcRecordTy)984 bool MicrosoftCXXABI::shouldTypeidBeNullChecked(bool IsDeref,
985 QualType SrcRecordTy) {
986 const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();
987 return IsDeref &&
988 !getContext().getASTRecordLayout(SrcDecl).hasExtendableVFPtr();
989 }
990
emitRTtypeidCall(CodeGenFunction & CGF,llvm::Value * Argument)991 static llvm::CallBase *emitRTtypeidCall(CodeGenFunction &CGF,
992 llvm::Value *Argument) {
993 llvm::Type *ArgTypes[] = {CGF.Int8PtrTy};
994 llvm::FunctionType *FTy =
995 llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false);
996 llvm::Value *Args[] = {Argument};
997 llvm::FunctionCallee Fn = CGF.CGM.CreateRuntimeFunction(FTy, "__RTtypeid");
998 return CGF.EmitRuntimeCallOrInvoke(Fn, Args);
999 }
1000
EmitBadTypeidCall(CodeGenFunction & CGF)1001 void MicrosoftCXXABI::EmitBadTypeidCall(CodeGenFunction &CGF) {
1002 llvm::CallBase *Call =
1003 emitRTtypeidCall(CGF, llvm::Constant::getNullValue(CGM.VoidPtrTy));
1004 Call->setDoesNotReturn();
1005 CGF.Builder.CreateUnreachable();
1006 }
1007
EmitTypeid(CodeGenFunction & CGF,QualType SrcRecordTy,Address ThisPtr,llvm::Type * StdTypeInfoPtrTy)1008 llvm::Value *MicrosoftCXXABI::EmitTypeid(CodeGenFunction &CGF,
1009 QualType SrcRecordTy,
1010 Address ThisPtr,
1011 llvm::Type *StdTypeInfoPtrTy) {
1012 std::tie(ThisPtr, std::ignore, std::ignore) =
1013 performBaseAdjustment(CGF, ThisPtr, SrcRecordTy);
1014 llvm::CallBase *Typeid = emitRTtypeidCall(CGF, ThisPtr.getPointer());
1015 return CGF.Builder.CreateBitCast(Typeid, StdTypeInfoPtrTy);
1016 }
1017
shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,QualType SrcRecordTy)1018 bool MicrosoftCXXABI::shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,
1019 QualType SrcRecordTy) {
1020 const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();
1021 return SrcIsPtr &&
1022 !getContext().getASTRecordLayout(SrcDecl).hasExtendableVFPtr();
1023 }
1024
emitDynamicCastCall(CodeGenFunction & CGF,Address This,QualType SrcRecordTy,QualType DestTy,QualType DestRecordTy,llvm::BasicBlock * CastEnd)1025 llvm::Value *MicrosoftCXXABI::emitDynamicCastCall(
1026 CodeGenFunction &CGF, Address This, QualType SrcRecordTy, QualType DestTy,
1027 QualType DestRecordTy, llvm::BasicBlock *CastEnd) {
1028 llvm::Value *SrcRTTI =
1029 CGF.CGM.GetAddrOfRTTIDescriptor(SrcRecordTy.getUnqualifiedType());
1030 llvm::Value *DestRTTI =
1031 CGF.CGM.GetAddrOfRTTIDescriptor(DestRecordTy.getUnqualifiedType());
1032
1033 llvm::Value *Offset;
1034 std::tie(This, Offset, std::ignore) =
1035 performBaseAdjustment(CGF, This, SrcRecordTy);
1036 llvm::Value *ThisPtr = This.getPointer();
1037 Offset = CGF.Builder.CreateTrunc(Offset, CGF.Int32Ty);
1038
1039 // PVOID __RTDynamicCast(
1040 // PVOID inptr,
1041 // LONG VfDelta,
1042 // PVOID SrcType,
1043 // PVOID TargetType,
1044 // BOOL isReference)
1045 llvm::Type *ArgTypes[] = {CGF.Int8PtrTy, CGF.Int32Ty, CGF.Int8PtrTy,
1046 CGF.Int8PtrTy, CGF.Int32Ty};
1047 llvm::FunctionCallee Function = CGF.CGM.CreateRuntimeFunction(
1048 llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false),
1049 "__RTDynamicCast");
1050 llvm::Value *Args[] = {
1051 ThisPtr, Offset, SrcRTTI, DestRTTI,
1052 llvm::ConstantInt::get(CGF.Int32Ty, DestTy->isReferenceType())};
1053 return CGF.EmitRuntimeCallOrInvoke(Function, Args);
1054 }
1055
emitDynamicCastToVoid(CodeGenFunction & CGF,Address Value,QualType SrcRecordTy)1056 llvm::Value *MicrosoftCXXABI::emitDynamicCastToVoid(CodeGenFunction &CGF,
1057 Address Value,
1058 QualType SrcRecordTy) {
1059 std::tie(Value, std::ignore, std::ignore) =
1060 performBaseAdjustment(CGF, Value, SrcRecordTy);
1061
1062 // PVOID __RTCastToVoid(
1063 // PVOID inptr)
1064 llvm::Type *ArgTypes[] = {CGF.Int8PtrTy};
1065 llvm::FunctionCallee Function = CGF.CGM.CreateRuntimeFunction(
1066 llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false),
1067 "__RTCastToVoid");
1068 llvm::Value *Args[] = {Value.getPointer()};
1069 return CGF.EmitRuntimeCall(Function, Args);
1070 }
1071
EmitBadCastCall(CodeGenFunction & CGF)1072 bool MicrosoftCXXABI::EmitBadCastCall(CodeGenFunction &CGF) {
1073 return false;
1074 }
1075
GetVirtualBaseClassOffset(CodeGenFunction & CGF,Address This,const CXXRecordDecl * ClassDecl,const CXXRecordDecl * BaseClassDecl)1076 llvm::Value *MicrosoftCXXABI::GetVirtualBaseClassOffset(
1077 CodeGenFunction &CGF, Address This, const CXXRecordDecl *ClassDecl,
1078 const CXXRecordDecl *BaseClassDecl) {
1079 const ASTContext &Context = getContext();
1080 int64_t VBPtrChars =
1081 Context.getASTRecordLayout(ClassDecl).getVBPtrOffset().getQuantity();
1082 llvm::Value *VBPtrOffset = llvm::ConstantInt::get(CGM.PtrDiffTy, VBPtrChars);
1083 CharUnits IntSize = Context.getTypeSizeInChars(Context.IntTy);
1084 CharUnits VBTableChars =
1085 IntSize *
1086 CGM.getMicrosoftVTableContext().getVBTableIndex(ClassDecl, BaseClassDecl);
1087 llvm::Value *VBTableOffset =
1088 llvm::ConstantInt::get(CGM.IntTy, VBTableChars.getQuantity());
1089
1090 llvm::Value *VBPtrToNewBase =
1091 GetVBaseOffsetFromVBPtr(CGF, This, VBPtrOffset, VBTableOffset);
1092 VBPtrToNewBase =
1093 CGF.Builder.CreateSExtOrBitCast(VBPtrToNewBase, CGM.PtrDiffTy);
1094 return CGF.Builder.CreateNSWAdd(VBPtrOffset, VBPtrToNewBase);
1095 }
1096
HasThisReturn(GlobalDecl GD) const1097 bool MicrosoftCXXABI::HasThisReturn(GlobalDecl GD) const {
1098 return isa<CXXConstructorDecl>(GD.getDecl());
1099 }
1100
isDeletingDtor(GlobalDecl GD)1101 static bool isDeletingDtor(GlobalDecl GD) {
1102 return isa<CXXDestructorDecl>(GD.getDecl()) &&
1103 GD.getDtorType() == Dtor_Deleting;
1104 }
1105
hasMostDerivedReturn(GlobalDecl GD) const1106 bool MicrosoftCXXABI::hasMostDerivedReturn(GlobalDecl GD) const {
1107 return isDeletingDtor(GD);
1108 }
1109
isTrivialForMSVC(const CXXRecordDecl * RD,QualType Ty,CodeGenModule & CGM)1110 static bool isTrivialForMSVC(const CXXRecordDecl *RD, QualType Ty,
1111 CodeGenModule &CGM) {
1112 // On AArch64, HVAs that can be passed in registers can also be returned
1113 // in registers. (Note this is using the MSVC definition of an HVA; see
1114 // isPermittedToBeHomogeneousAggregate().)
1115 const Type *Base = nullptr;
1116 uint64_t NumElts = 0;
1117 if (CGM.getTarget().getTriple().isAArch64() &&
1118 CGM.getTypes().getABIInfo().isHomogeneousAggregate(Ty, Base, NumElts) &&
1119 isa<VectorType>(Base)) {
1120 return true;
1121 }
1122
1123 // We use the C++14 definition of an aggregate, so we also
1124 // check for:
1125 // No private or protected non static data members.
1126 // No base classes
1127 // No virtual functions
1128 // Additionally, we need to ensure that there is a trivial copy assignment
1129 // operator, a trivial destructor and no user-provided constructors.
1130 if (RD->hasProtectedFields() || RD->hasPrivateFields())
1131 return false;
1132 if (RD->getNumBases() > 0)
1133 return false;
1134 if (RD->isPolymorphic())
1135 return false;
1136 if (RD->hasNonTrivialCopyAssignment())
1137 return false;
1138 for (const Decl *D : RD->decls()) {
1139 if (auto *Ctor = dyn_cast<CXXConstructorDecl>(D)) {
1140 if (Ctor->isUserProvided())
1141 return false;
1142 } else if (auto *Template = dyn_cast<FunctionTemplateDecl>(D)) {
1143 if (isa<CXXConstructorDecl>(Template->getTemplatedDecl()))
1144 return false;
1145 }
1146 }
1147 if (RD->hasNonTrivialDestructor())
1148 return false;
1149 return true;
1150 }
1151
classifyReturnType(CGFunctionInfo & FI) const1152 bool MicrosoftCXXABI::classifyReturnType(CGFunctionInfo &FI) const {
1153 const CXXRecordDecl *RD = FI.getReturnType()->getAsCXXRecordDecl();
1154 if (!RD)
1155 return false;
1156
1157 bool isTrivialForABI = RD->canPassInRegisters() &&
1158 isTrivialForMSVC(RD, FI.getReturnType(), CGM);
1159
1160 // MSVC always returns structs indirectly from C++ instance methods.
1161 bool isIndirectReturn = !isTrivialForABI || FI.isInstanceMethod();
1162
1163 if (isIndirectReturn) {
1164 CharUnits Align = CGM.getContext().getTypeAlignInChars(FI.getReturnType());
1165 FI.getReturnInfo() = ABIArgInfo::getIndirect(Align, /*ByVal=*/false);
1166
1167 // MSVC always passes `this` before the `sret` parameter.
1168 FI.getReturnInfo().setSRetAfterThis(FI.isInstanceMethod());
1169
1170 // On AArch64, use the `inreg` attribute if the object is considered to not
1171 // be trivially copyable, or if this is an instance method struct return.
1172 FI.getReturnInfo().setInReg(CGM.getTarget().getTriple().isAArch64());
1173
1174 return true;
1175 }
1176
1177 // Otherwise, use the C ABI rules.
1178 return false;
1179 }
1180
1181 llvm::BasicBlock *
EmitCtorCompleteObjectHandler(CodeGenFunction & CGF,const CXXRecordDecl * RD)1182 MicrosoftCXXABI::EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
1183 const CXXRecordDecl *RD) {
1184 llvm::Value *IsMostDerivedClass = getStructorImplicitParamValue(CGF);
1185 assert(IsMostDerivedClass &&
1186 "ctor for a class with virtual bases must have an implicit parameter");
1187 llvm::Value *IsCompleteObject =
1188 CGF.Builder.CreateIsNotNull(IsMostDerivedClass, "is_complete_object");
1189
1190 llvm::BasicBlock *CallVbaseCtorsBB = CGF.createBasicBlock("ctor.init_vbases");
1191 llvm::BasicBlock *SkipVbaseCtorsBB = CGF.createBasicBlock("ctor.skip_vbases");
1192 CGF.Builder.CreateCondBr(IsCompleteObject,
1193 CallVbaseCtorsBB, SkipVbaseCtorsBB);
1194
1195 CGF.EmitBlock(CallVbaseCtorsBB);
1196
1197 // Fill in the vbtable pointers here.
1198 EmitVBPtrStores(CGF, RD);
1199
1200 // CGF will put the base ctor calls in this basic block for us later.
1201
1202 return SkipVbaseCtorsBB;
1203 }
1204
1205 llvm::BasicBlock *
EmitDtorCompleteObjectHandler(CodeGenFunction & CGF)1206 MicrosoftCXXABI::EmitDtorCompleteObjectHandler(CodeGenFunction &CGF) {
1207 llvm::Value *IsMostDerivedClass = getStructorImplicitParamValue(CGF);
1208 assert(IsMostDerivedClass &&
1209 "ctor for a class with virtual bases must have an implicit parameter");
1210 llvm::Value *IsCompleteObject =
1211 CGF.Builder.CreateIsNotNull(IsMostDerivedClass, "is_complete_object");
1212
1213 llvm::BasicBlock *CallVbaseDtorsBB = CGF.createBasicBlock("Dtor.dtor_vbases");
1214 llvm::BasicBlock *SkipVbaseDtorsBB = CGF.createBasicBlock("Dtor.skip_vbases");
1215 CGF.Builder.CreateCondBr(IsCompleteObject,
1216 CallVbaseDtorsBB, SkipVbaseDtorsBB);
1217
1218 CGF.EmitBlock(CallVbaseDtorsBB);
1219 // CGF will put the base dtor calls in this basic block for us later.
1220
1221 return SkipVbaseDtorsBB;
1222 }
1223
initializeHiddenVirtualInheritanceMembers(CodeGenFunction & CGF,const CXXRecordDecl * RD)1224 void MicrosoftCXXABI::initializeHiddenVirtualInheritanceMembers(
1225 CodeGenFunction &CGF, const CXXRecordDecl *RD) {
1226 // In most cases, an override for a vbase virtual method can adjust
1227 // the "this" parameter by applying a constant offset.
1228 // However, this is not enough while a constructor or a destructor of some
1229 // class X is being executed if all the following conditions are met:
1230 // - X has virtual bases, (1)
1231 // - X overrides a virtual method M of a vbase Y, (2)
1232 // - X itself is a vbase of the most derived class.
1233 //
1234 // If (1) and (2) are true, the vtorDisp for vbase Y is a hidden member of X
1235 // which holds the extra amount of "this" adjustment we must do when we use
1236 // the X vftables (i.e. during X ctor or dtor).
1237 // Outside the ctors and dtors, the values of vtorDisps are zero.
1238
1239 const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
1240 typedef ASTRecordLayout::VBaseOffsetsMapTy VBOffsets;
1241 const VBOffsets &VBaseMap = Layout.getVBaseOffsetsMap();
1242 CGBuilderTy &Builder = CGF.Builder;
1243
1244 llvm::Value *Int8This = nullptr; // Initialize lazily.
1245
1246 for (const CXXBaseSpecifier &S : RD->vbases()) {
1247 const CXXRecordDecl *VBase = S.getType()->getAsCXXRecordDecl();
1248 auto I = VBaseMap.find(VBase);
1249 assert(I != VBaseMap.end());
1250 if (!I->second.hasVtorDisp())
1251 continue;
1252
1253 llvm::Value *VBaseOffset =
1254 GetVirtualBaseClassOffset(CGF, getThisAddress(CGF), RD, VBase);
1255 uint64_t ConstantVBaseOffset = I->second.VBaseOffset.getQuantity();
1256
1257 // vtorDisp_for_vbase = vbptr[vbase_idx] - offsetof(RD, vbase).
1258 llvm::Value *VtorDispValue = Builder.CreateSub(
1259 VBaseOffset, llvm::ConstantInt::get(CGM.PtrDiffTy, ConstantVBaseOffset),
1260 "vtordisp.value");
1261 VtorDispValue = Builder.CreateTruncOrBitCast(VtorDispValue, CGF.Int32Ty);
1262
1263 if (!Int8This)
1264 Int8This = getThisValue(CGF);
1265
1266 llvm::Value *VtorDispPtr =
1267 Builder.CreateInBoundsGEP(CGF.Int8Ty, Int8This, VBaseOffset);
1268 // vtorDisp is always the 32-bits before the vbase in the class layout.
1269 VtorDispPtr = Builder.CreateConstGEP1_32(CGF.Int8Ty, VtorDispPtr, -4);
1270
1271 Builder.CreateAlignedStore(VtorDispValue, VtorDispPtr,
1272 CharUnits::fromQuantity(4));
1273 }
1274 }
1275
hasDefaultCXXMethodCC(ASTContext & Context,const CXXMethodDecl * MD)1276 static bool hasDefaultCXXMethodCC(ASTContext &Context,
1277 const CXXMethodDecl *MD) {
1278 CallingConv ExpectedCallingConv = Context.getDefaultCallingConvention(
1279 /*IsVariadic=*/false, /*IsCXXMethod=*/true);
1280 CallingConv ActualCallingConv =
1281 MD->getType()->castAs<FunctionProtoType>()->getCallConv();
1282 return ExpectedCallingConv == ActualCallingConv;
1283 }
1284
EmitCXXConstructors(const CXXConstructorDecl * D)1285 void MicrosoftCXXABI::EmitCXXConstructors(const CXXConstructorDecl *D) {
1286 // There's only one constructor type in this ABI.
1287 CGM.EmitGlobal(GlobalDecl(D, Ctor_Complete));
1288
1289 // Exported default constructors either have a simple call-site where they use
1290 // the typical calling convention and have a single 'this' pointer for an
1291 // argument -or- they get a wrapper function which appropriately thunks to the
1292 // real default constructor. This thunk is the default constructor closure.
1293 if (D->hasAttr<DLLExportAttr>() && D->isDefaultConstructor() &&
1294 D->isDefined()) {
1295 if (!hasDefaultCXXMethodCC(getContext(), D) || D->getNumParams() != 0) {
1296 llvm::Function *Fn = getAddrOfCXXCtorClosure(D, Ctor_DefaultClosure);
1297 Fn->setLinkage(llvm::GlobalValue::WeakODRLinkage);
1298 CGM.setGVProperties(Fn, D);
1299 }
1300 }
1301 }
1302
EmitVBPtrStores(CodeGenFunction & CGF,const CXXRecordDecl * RD)1303 void MicrosoftCXXABI::EmitVBPtrStores(CodeGenFunction &CGF,
1304 const CXXRecordDecl *RD) {
1305 Address This = getThisAddress(CGF);
1306 This = This.withElementType(CGM.Int8Ty);
1307 const ASTContext &Context = getContext();
1308 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1309
1310 const VBTableGlobals &VBGlobals = enumerateVBTables(RD);
1311 for (unsigned I = 0, E = VBGlobals.VBTables->size(); I != E; ++I) {
1312 const std::unique_ptr<VPtrInfo> &VBT = (*VBGlobals.VBTables)[I];
1313 llvm::GlobalVariable *GV = VBGlobals.Globals[I];
1314 const ASTRecordLayout &SubobjectLayout =
1315 Context.getASTRecordLayout(VBT->IntroducingObject);
1316 CharUnits Offs = VBT->NonVirtualOffset;
1317 Offs += SubobjectLayout.getVBPtrOffset();
1318 if (VBT->getVBaseWithVPtr())
1319 Offs += Layout.getVBaseClassOffset(VBT->getVBaseWithVPtr());
1320 Address VBPtr = CGF.Builder.CreateConstInBoundsByteGEP(This, Offs);
1321 llvm::Value *GVPtr =
1322 CGF.Builder.CreateConstInBoundsGEP2_32(GV->getValueType(), GV, 0, 0);
1323 VBPtr = VBPtr.withElementType(GVPtr->getType());
1324 CGF.Builder.CreateStore(GVPtr, VBPtr);
1325 }
1326 }
1327
1328 CGCXXABI::AddedStructorArgCounts
buildStructorSignature(GlobalDecl GD,SmallVectorImpl<CanQualType> & ArgTys)1329 MicrosoftCXXABI::buildStructorSignature(GlobalDecl GD,
1330 SmallVectorImpl<CanQualType> &ArgTys) {
1331 AddedStructorArgCounts Added;
1332 // TODO: 'for base' flag
1333 if (isa<CXXDestructorDecl>(GD.getDecl()) &&
1334 GD.getDtorType() == Dtor_Deleting) {
1335 // The scalar deleting destructor takes an implicit int parameter.
1336 ArgTys.push_back(getContext().IntTy);
1337 ++Added.Suffix;
1338 }
1339 auto *CD = dyn_cast<CXXConstructorDecl>(GD.getDecl());
1340 if (!CD)
1341 return Added;
1342
1343 // All parameters are already in place except is_most_derived, which goes
1344 // after 'this' if it's variadic and last if it's not.
1345
1346 const CXXRecordDecl *Class = CD->getParent();
1347 const FunctionProtoType *FPT = CD->getType()->castAs<FunctionProtoType>();
1348 if (Class->getNumVBases()) {
1349 if (FPT->isVariadic()) {
1350 ArgTys.insert(ArgTys.begin() + 1, getContext().IntTy);
1351 ++Added.Prefix;
1352 } else {
1353 ArgTys.push_back(getContext().IntTy);
1354 ++Added.Suffix;
1355 }
1356 }
1357
1358 return Added;
1359 }
1360
setCXXDestructorDLLStorage(llvm::GlobalValue * GV,const CXXDestructorDecl * Dtor,CXXDtorType DT) const1361 void MicrosoftCXXABI::setCXXDestructorDLLStorage(llvm::GlobalValue *GV,
1362 const CXXDestructorDecl *Dtor,
1363 CXXDtorType DT) const {
1364 // Deleting destructor variants are never imported or exported. Give them the
1365 // default storage class.
1366 if (DT == Dtor_Deleting) {
1367 GV->setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass);
1368 } else {
1369 const NamedDecl *ND = Dtor;
1370 CGM.setDLLImportDLLExport(GV, ND);
1371 }
1372 }
1373
getCXXDestructorLinkage(GVALinkage Linkage,const CXXDestructorDecl * Dtor,CXXDtorType DT) const1374 llvm::GlobalValue::LinkageTypes MicrosoftCXXABI::getCXXDestructorLinkage(
1375 GVALinkage Linkage, const CXXDestructorDecl *Dtor, CXXDtorType DT) const {
1376 // Internal things are always internal, regardless of attributes. After this,
1377 // we know the thunk is externally visible.
1378 if (Linkage == GVA_Internal)
1379 return llvm::GlobalValue::InternalLinkage;
1380
1381 switch (DT) {
1382 case Dtor_Base:
1383 // The base destructor most closely tracks the user-declared constructor, so
1384 // we delegate back to the normal declarator case.
1385 return CGM.getLLVMLinkageForDeclarator(Dtor, Linkage);
1386 case Dtor_Complete:
1387 // The complete destructor is like an inline function, but it may be
1388 // imported and therefore must be exported as well. This requires changing
1389 // the linkage if a DLL attribute is present.
1390 if (Dtor->hasAttr<DLLExportAttr>())
1391 return llvm::GlobalValue::WeakODRLinkage;
1392 if (Dtor->hasAttr<DLLImportAttr>())
1393 return llvm::GlobalValue::AvailableExternallyLinkage;
1394 return llvm::GlobalValue::LinkOnceODRLinkage;
1395 case Dtor_Deleting:
1396 // Deleting destructors are like inline functions. They have vague linkage
1397 // and are emitted everywhere they are used. They are internal if the class
1398 // is internal.
1399 return llvm::GlobalValue::LinkOnceODRLinkage;
1400 case Dtor_Comdat:
1401 llvm_unreachable("MS C++ ABI does not support comdat dtors");
1402 }
1403 llvm_unreachable("invalid dtor type");
1404 }
1405
EmitCXXDestructors(const CXXDestructorDecl * D)1406 void MicrosoftCXXABI::EmitCXXDestructors(const CXXDestructorDecl *D) {
1407 // The TU defining a dtor is only guaranteed to emit a base destructor. All
1408 // other destructor variants are delegating thunks.
1409 CGM.EmitGlobal(GlobalDecl(D, Dtor_Base));
1410
1411 // If the class is dllexported, emit the complete (vbase) destructor wherever
1412 // the base dtor is emitted.
1413 // FIXME: To match MSVC, this should only be done when the class is exported
1414 // with -fdllexport-inlines enabled.
1415 if (D->getParent()->getNumVBases() > 0 && D->hasAttr<DLLExportAttr>())
1416 CGM.EmitGlobal(GlobalDecl(D, Dtor_Complete));
1417 }
1418
1419 CharUnits
getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD)1420 MicrosoftCXXABI::getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) {
1421 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
1422
1423 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1424 // Complete destructors take a pointer to the complete object as a
1425 // parameter, thus don't need this adjustment.
1426 if (GD.getDtorType() == Dtor_Complete)
1427 return CharUnits();
1428
1429 // There's no Dtor_Base in vftable but it shares the this adjustment with
1430 // the deleting one, so look it up instead.
1431 GD = GlobalDecl(DD, Dtor_Deleting);
1432 }
1433
1434 MethodVFTableLocation ML =
1435 CGM.getMicrosoftVTableContext().getMethodVFTableLocation(GD);
1436 CharUnits Adjustment = ML.VFPtrOffset;
1437
1438 // Normal virtual instance methods need to adjust from the vfptr that first
1439 // defined the virtual method to the virtual base subobject, but destructors
1440 // do not. The vector deleting destructor thunk applies this adjustment for
1441 // us if necessary.
1442 if (isa<CXXDestructorDecl>(MD))
1443 Adjustment = CharUnits::Zero();
1444
1445 if (ML.VBase) {
1446 const ASTRecordLayout &DerivedLayout =
1447 getContext().getASTRecordLayout(MD->getParent());
1448 Adjustment += DerivedLayout.getVBaseClassOffset(ML.VBase);
1449 }
1450
1451 return Adjustment;
1452 }
1453
adjustThisArgumentForVirtualFunctionCall(CodeGenFunction & CGF,GlobalDecl GD,Address This,bool VirtualCall)1454 Address MicrosoftCXXABI::adjustThisArgumentForVirtualFunctionCall(
1455 CodeGenFunction &CGF, GlobalDecl GD, Address This,
1456 bool VirtualCall) {
1457 if (!VirtualCall) {
1458 // If the call of a virtual function is not virtual, we just have to
1459 // compensate for the adjustment the virtual function does in its prologue.
1460 CharUnits Adjustment = getVirtualFunctionPrologueThisAdjustment(GD);
1461 if (Adjustment.isZero())
1462 return This;
1463
1464 This = This.withElementType(CGF.Int8Ty);
1465 assert(Adjustment.isPositive());
1466 return CGF.Builder.CreateConstByteGEP(This, Adjustment);
1467 }
1468
1469 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
1470
1471 GlobalDecl LookupGD = GD;
1472 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1473 // Complete dtors take a pointer to the complete object,
1474 // thus don't need adjustment.
1475 if (GD.getDtorType() == Dtor_Complete)
1476 return This;
1477
1478 // There's only Dtor_Deleting in vftable but it shares the this adjustment
1479 // with the base one, so look up the deleting one instead.
1480 LookupGD = GlobalDecl(DD, Dtor_Deleting);
1481 }
1482 MethodVFTableLocation ML =
1483 CGM.getMicrosoftVTableContext().getMethodVFTableLocation(LookupGD);
1484
1485 CharUnits StaticOffset = ML.VFPtrOffset;
1486
1487 // Base destructors expect 'this' to point to the beginning of the base
1488 // subobject, not the first vfptr that happens to contain the virtual dtor.
1489 // However, we still need to apply the virtual base adjustment.
1490 if (isa<CXXDestructorDecl>(MD) && GD.getDtorType() == Dtor_Base)
1491 StaticOffset = CharUnits::Zero();
1492
1493 Address Result = This;
1494 if (ML.VBase) {
1495 Result = Result.withElementType(CGF.Int8Ty);
1496
1497 const CXXRecordDecl *Derived = MD->getParent();
1498 const CXXRecordDecl *VBase = ML.VBase;
1499 llvm::Value *VBaseOffset =
1500 GetVirtualBaseClassOffset(CGF, Result, Derived, VBase);
1501 llvm::Value *VBasePtr = CGF.Builder.CreateInBoundsGEP(
1502 Result.getElementType(), Result.getPointer(), VBaseOffset);
1503 CharUnits VBaseAlign =
1504 CGF.CGM.getVBaseAlignment(Result.getAlignment(), Derived, VBase);
1505 Result = Address(VBasePtr, CGF.Int8Ty, VBaseAlign);
1506 }
1507 if (!StaticOffset.isZero()) {
1508 assert(StaticOffset.isPositive());
1509 Result = Result.withElementType(CGF.Int8Ty);
1510 if (ML.VBase) {
1511 // Non-virtual adjustment might result in a pointer outside the allocated
1512 // object, e.g. if the final overrider class is laid out after the virtual
1513 // base that declares a method in the most derived class.
1514 // FIXME: Update the code that emits this adjustment in thunks prologues.
1515 Result = CGF.Builder.CreateConstByteGEP(Result, StaticOffset);
1516 } else {
1517 Result = CGF.Builder.CreateConstInBoundsByteGEP(Result, StaticOffset);
1518 }
1519 }
1520 return Result;
1521 }
1522
addImplicitStructorParams(CodeGenFunction & CGF,QualType & ResTy,FunctionArgList & Params)1523 void MicrosoftCXXABI::addImplicitStructorParams(CodeGenFunction &CGF,
1524 QualType &ResTy,
1525 FunctionArgList &Params) {
1526 ASTContext &Context = getContext();
1527 const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
1528 assert(isa<CXXConstructorDecl>(MD) || isa<CXXDestructorDecl>(MD));
1529 if (isa<CXXConstructorDecl>(MD) && MD->getParent()->getNumVBases()) {
1530 auto *IsMostDerived = ImplicitParamDecl::Create(
1531 Context, /*DC=*/nullptr, CGF.CurGD.getDecl()->getLocation(),
1532 &Context.Idents.get("is_most_derived"), Context.IntTy,
1533 ImplicitParamKind::Other);
1534 // The 'most_derived' parameter goes second if the ctor is variadic and last
1535 // if it's not. Dtors can't be variadic.
1536 const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>();
1537 if (FPT->isVariadic())
1538 Params.insert(Params.begin() + 1, IsMostDerived);
1539 else
1540 Params.push_back(IsMostDerived);
1541 getStructorImplicitParamDecl(CGF) = IsMostDerived;
1542 } else if (isDeletingDtor(CGF.CurGD)) {
1543 auto *ShouldDelete = ImplicitParamDecl::Create(
1544 Context, /*DC=*/nullptr, CGF.CurGD.getDecl()->getLocation(),
1545 &Context.Idents.get("should_call_delete"), Context.IntTy,
1546 ImplicitParamKind::Other);
1547 Params.push_back(ShouldDelete);
1548 getStructorImplicitParamDecl(CGF) = ShouldDelete;
1549 }
1550 }
1551
EmitInstanceFunctionProlog(CodeGenFunction & CGF)1552 void MicrosoftCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) {
1553 // Naked functions have no prolog.
1554 if (CGF.CurFuncDecl && CGF.CurFuncDecl->hasAttr<NakedAttr>())
1555 return;
1556
1557 // Overridden virtual methods of non-primary bases need to adjust the incoming
1558 // 'this' pointer in the prologue. In this hierarchy, C::b will subtract
1559 // sizeof(void*) to adjust from B* to C*:
1560 // struct A { virtual void a(); };
1561 // struct B { virtual void b(); };
1562 // struct C : A, B { virtual void b(); };
1563 //
1564 // Leave the value stored in the 'this' alloca unadjusted, so that the
1565 // debugger sees the unadjusted value. Microsoft debuggers require this, and
1566 // will apply the ThisAdjustment in the method type information.
1567 // FIXME: Do something better for DWARF debuggers, which won't expect this,
1568 // without making our codegen depend on debug info settings.
1569 llvm::Value *This = loadIncomingCXXThis(CGF);
1570 const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
1571 if (!CGF.CurFuncIsThunk && MD->isVirtual()) {
1572 CharUnits Adjustment = getVirtualFunctionPrologueThisAdjustment(CGF.CurGD);
1573 if (!Adjustment.isZero()) {
1574 assert(Adjustment.isPositive());
1575 This = CGF.Builder.CreateConstInBoundsGEP1_32(CGF.Int8Ty, This,
1576 -Adjustment.getQuantity());
1577 }
1578 }
1579 setCXXABIThisValue(CGF, This);
1580
1581 // If this is a function that the ABI specifies returns 'this', initialize
1582 // the return slot to 'this' at the start of the function.
1583 //
1584 // Unlike the setting of return types, this is done within the ABI
1585 // implementation instead of by clients of CGCXXABI because:
1586 // 1) getThisValue is currently protected
1587 // 2) in theory, an ABI could implement 'this' returns some other way;
1588 // HasThisReturn only specifies a contract, not the implementation
1589 if (HasThisReturn(CGF.CurGD) || hasMostDerivedReturn(CGF.CurGD))
1590 CGF.Builder.CreateStore(getThisValue(CGF), CGF.ReturnValue);
1591
1592 if (isa<CXXConstructorDecl>(MD) && MD->getParent()->getNumVBases()) {
1593 assert(getStructorImplicitParamDecl(CGF) &&
1594 "no implicit parameter for a constructor with virtual bases?");
1595 getStructorImplicitParamValue(CGF)
1596 = CGF.Builder.CreateLoad(
1597 CGF.GetAddrOfLocalVar(getStructorImplicitParamDecl(CGF)),
1598 "is_most_derived");
1599 }
1600
1601 if (isDeletingDtor(CGF.CurGD)) {
1602 assert(getStructorImplicitParamDecl(CGF) &&
1603 "no implicit parameter for a deleting destructor?");
1604 getStructorImplicitParamValue(CGF)
1605 = CGF.Builder.CreateLoad(
1606 CGF.GetAddrOfLocalVar(getStructorImplicitParamDecl(CGF)),
1607 "should_call_delete");
1608 }
1609 }
1610
getImplicitConstructorArgs(CodeGenFunction & CGF,const CXXConstructorDecl * D,CXXCtorType Type,bool ForVirtualBase,bool Delegating)1611 CGCXXABI::AddedStructorArgs MicrosoftCXXABI::getImplicitConstructorArgs(
1612 CodeGenFunction &CGF, const CXXConstructorDecl *D, CXXCtorType Type,
1613 bool ForVirtualBase, bool Delegating) {
1614 assert(Type == Ctor_Complete || Type == Ctor_Base);
1615
1616 // Check if we need a 'most_derived' parameter.
1617 if (!D->getParent()->getNumVBases())
1618 return AddedStructorArgs{};
1619
1620 // Add the 'most_derived' argument second if we are variadic or last if not.
1621 const FunctionProtoType *FPT = D->getType()->castAs<FunctionProtoType>();
1622 llvm::Value *MostDerivedArg;
1623 if (Delegating) {
1624 MostDerivedArg = getStructorImplicitParamValue(CGF);
1625 } else {
1626 MostDerivedArg = llvm::ConstantInt::get(CGM.Int32Ty, Type == Ctor_Complete);
1627 }
1628 if (FPT->isVariadic()) {
1629 return AddedStructorArgs::prefix({{MostDerivedArg, getContext().IntTy}});
1630 }
1631 return AddedStructorArgs::suffix({{MostDerivedArg, getContext().IntTy}});
1632 }
1633
getCXXDestructorImplicitParam(CodeGenFunction & CGF,const CXXDestructorDecl * DD,CXXDtorType Type,bool ForVirtualBase,bool Delegating)1634 llvm::Value *MicrosoftCXXABI::getCXXDestructorImplicitParam(
1635 CodeGenFunction &CGF, const CXXDestructorDecl *DD, CXXDtorType Type,
1636 bool ForVirtualBase, bool Delegating) {
1637 return nullptr;
1638 }
1639
EmitDestructorCall(CodeGenFunction & CGF,const CXXDestructorDecl * DD,CXXDtorType Type,bool ForVirtualBase,bool Delegating,Address This,QualType ThisTy)1640 void MicrosoftCXXABI::EmitDestructorCall(CodeGenFunction &CGF,
1641 const CXXDestructorDecl *DD,
1642 CXXDtorType Type, bool ForVirtualBase,
1643 bool Delegating, Address This,
1644 QualType ThisTy) {
1645 // Use the base destructor variant in place of the complete destructor variant
1646 // if the class has no virtual bases. This effectively implements some of the
1647 // -mconstructor-aliases optimization, but as part of the MS C++ ABI.
1648 if (Type == Dtor_Complete && DD->getParent()->getNumVBases() == 0)
1649 Type = Dtor_Base;
1650
1651 GlobalDecl GD(DD, Type);
1652 CGCallee Callee = CGCallee::forDirect(CGM.getAddrOfCXXStructor(GD), GD);
1653
1654 if (DD->isVirtual()) {
1655 assert(Type != CXXDtorType::Dtor_Deleting &&
1656 "The deleting destructor should only be called via a virtual call");
1657 This = adjustThisArgumentForVirtualFunctionCall(CGF, GlobalDecl(DD, Type),
1658 This, false);
1659 }
1660
1661 llvm::BasicBlock *BaseDtorEndBB = nullptr;
1662 if (ForVirtualBase && isa<CXXConstructorDecl>(CGF.CurCodeDecl)) {
1663 BaseDtorEndBB = EmitDtorCompleteObjectHandler(CGF);
1664 }
1665
1666 llvm::Value *Implicit =
1667 getCXXDestructorImplicitParam(CGF, DD, Type, ForVirtualBase,
1668 Delegating); // = nullptr
1669 CGF.EmitCXXDestructorCall(GD, Callee, This.getPointer(), ThisTy,
1670 /*ImplicitParam=*/Implicit,
1671 /*ImplicitParamTy=*/QualType(), nullptr);
1672 if (BaseDtorEndBB) {
1673 // Complete object handler should continue to be the remaining
1674 CGF.Builder.CreateBr(BaseDtorEndBB);
1675 CGF.EmitBlock(BaseDtorEndBB);
1676 }
1677 }
1678
emitVTableTypeMetadata(const VPtrInfo & Info,const CXXRecordDecl * RD,llvm::GlobalVariable * VTable)1679 void MicrosoftCXXABI::emitVTableTypeMetadata(const VPtrInfo &Info,
1680 const CXXRecordDecl *RD,
1681 llvm::GlobalVariable *VTable) {
1682 // Emit type metadata on vtables with LTO or IR instrumentation.
1683 // In IR instrumentation, the type metadata could be used to find out vtable
1684 // definitions (for type profiling) among all global variables.
1685 if (!CGM.getCodeGenOpts().LTOUnit &&
1686 !CGM.getCodeGenOpts().hasProfileIRInstr())
1687 return;
1688
1689 // TODO: Should VirtualFunctionElimination also be supported here?
1690 // See similar handling in CodeGenModule::EmitVTableTypeMetadata.
1691 if (CGM.getCodeGenOpts().WholeProgramVTables) {
1692 llvm::DenseSet<const CXXRecordDecl *> Visited;
1693 llvm::GlobalObject::VCallVisibility TypeVis =
1694 CGM.GetVCallVisibilityLevel(RD, Visited);
1695 if (TypeVis != llvm::GlobalObject::VCallVisibilityPublic)
1696 VTable->setVCallVisibilityMetadata(TypeVis);
1697 }
1698
1699 // The location of the first virtual function pointer in the virtual table,
1700 // aka the "address point" on Itanium. This is at offset 0 if RTTI is
1701 // disabled, or sizeof(void*) if RTTI is enabled.
1702 CharUnits AddressPoint =
1703 getContext().getLangOpts().RTTIData
1704 ? getContext().toCharUnitsFromBits(
1705 getContext().getTargetInfo().getPointerWidth(LangAS::Default))
1706 : CharUnits::Zero();
1707
1708 if (Info.PathToIntroducingObject.empty()) {
1709 CGM.AddVTableTypeMetadata(VTable, AddressPoint, RD);
1710 return;
1711 }
1712
1713 // Add a bitset entry for the least derived base belonging to this vftable.
1714 CGM.AddVTableTypeMetadata(VTable, AddressPoint,
1715 Info.PathToIntroducingObject.back());
1716
1717 // Add a bitset entry for each derived class that is laid out at the same
1718 // offset as the least derived base.
1719 for (unsigned I = Info.PathToIntroducingObject.size() - 1; I != 0; --I) {
1720 const CXXRecordDecl *DerivedRD = Info.PathToIntroducingObject[I - 1];
1721 const CXXRecordDecl *BaseRD = Info.PathToIntroducingObject[I];
1722
1723 const ASTRecordLayout &Layout =
1724 getContext().getASTRecordLayout(DerivedRD);
1725 CharUnits Offset;
1726 auto VBI = Layout.getVBaseOffsetsMap().find(BaseRD);
1727 if (VBI == Layout.getVBaseOffsetsMap().end())
1728 Offset = Layout.getBaseClassOffset(BaseRD);
1729 else
1730 Offset = VBI->second.VBaseOffset;
1731 if (!Offset.isZero())
1732 return;
1733 CGM.AddVTableTypeMetadata(VTable, AddressPoint, DerivedRD);
1734 }
1735
1736 // Finally do the same for the most derived class.
1737 if (Info.FullOffsetInMDC.isZero())
1738 CGM.AddVTableTypeMetadata(VTable, AddressPoint, RD);
1739 }
1740
emitVTableDefinitions(CodeGenVTables & CGVT,const CXXRecordDecl * RD)1741 void MicrosoftCXXABI::emitVTableDefinitions(CodeGenVTables &CGVT,
1742 const CXXRecordDecl *RD) {
1743 MicrosoftVTableContext &VFTContext = CGM.getMicrosoftVTableContext();
1744 const VPtrInfoVector &VFPtrs = VFTContext.getVFPtrOffsets(RD);
1745
1746 for (const std::unique_ptr<VPtrInfo>& Info : VFPtrs) {
1747 llvm::GlobalVariable *VTable = getAddrOfVTable(RD, Info->FullOffsetInMDC);
1748 if (VTable->hasInitializer())
1749 continue;
1750
1751 const VTableLayout &VTLayout =
1752 VFTContext.getVFTableLayout(RD, Info->FullOffsetInMDC);
1753
1754 llvm::Constant *RTTI = nullptr;
1755 if (any_of(VTLayout.vtable_components(),
1756 [](const VTableComponent &VTC) { return VTC.isRTTIKind(); }))
1757 RTTI = getMSCompleteObjectLocator(RD, *Info);
1758
1759 ConstantInitBuilder builder(CGM);
1760 auto components = builder.beginStruct();
1761 CGVT.createVTableInitializer(components, VTLayout, RTTI,
1762 VTable->hasLocalLinkage());
1763 components.finishAndSetAsInitializer(VTable);
1764
1765 emitVTableTypeMetadata(*Info, RD, VTable);
1766 }
1767 }
1768
isVirtualOffsetNeededForVTableField(CodeGenFunction & CGF,CodeGenFunction::VPtr Vptr)1769 bool MicrosoftCXXABI::isVirtualOffsetNeededForVTableField(
1770 CodeGenFunction &CGF, CodeGenFunction::VPtr Vptr) {
1771 return Vptr.NearestVBase != nullptr;
1772 }
1773
getVTableAddressPointInStructor(CodeGenFunction & CGF,const CXXRecordDecl * VTableClass,BaseSubobject Base,const CXXRecordDecl * NearestVBase)1774 llvm::Value *MicrosoftCXXABI::getVTableAddressPointInStructor(
1775 CodeGenFunction &CGF, const CXXRecordDecl *VTableClass, BaseSubobject Base,
1776 const CXXRecordDecl *NearestVBase) {
1777 llvm::Constant *VTableAddressPoint = getVTableAddressPoint(Base, VTableClass);
1778 if (!VTableAddressPoint) {
1779 assert(Base.getBase()->getNumVBases() &&
1780 !getContext().getASTRecordLayout(Base.getBase()).hasOwnVFPtr());
1781 }
1782 return VTableAddressPoint;
1783 }
1784
mangleVFTableName(MicrosoftMangleContext & MangleContext,const CXXRecordDecl * RD,const VPtrInfo & VFPtr,SmallString<256> & Name)1785 static void mangleVFTableName(MicrosoftMangleContext &MangleContext,
1786 const CXXRecordDecl *RD, const VPtrInfo &VFPtr,
1787 SmallString<256> &Name) {
1788 llvm::raw_svector_ostream Out(Name);
1789 MangleContext.mangleCXXVFTable(RD, VFPtr.MangledPath, Out);
1790 }
1791
1792 llvm::Constant *
getVTableAddressPoint(BaseSubobject Base,const CXXRecordDecl * VTableClass)1793 MicrosoftCXXABI::getVTableAddressPoint(BaseSubobject Base,
1794 const CXXRecordDecl *VTableClass) {
1795 (void)getAddrOfVTable(VTableClass, Base.getBaseOffset());
1796 VFTableIdTy ID(VTableClass, Base.getBaseOffset());
1797 return VFTablesMap[ID];
1798 }
1799
getVTableAddressPointForConstExpr(BaseSubobject Base,const CXXRecordDecl * VTableClass)1800 llvm::Constant *MicrosoftCXXABI::getVTableAddressPointForConstExpr(
1801 BaseSubobject Base, const CXXRecordDecl *VTableClass) {
1802 llvm::Constant *VFTable = getVTableAddressPoint(Base, VTableClass);
1803 assert(VFTable && "Couldn't find a vftable for the given base?");
1804 return VFTable;
1805 }
1806
getAddrOfVTable(const CXXRecordDecl * RD,CharUnits VPtrOffset)1807 llvm::GlobalVariable *MicrosoftCXXABI::getAddrOfVTable(const CXXRecordDecl *RD,
1808 CharUnits VPtrOffset) {
1809 // getAddrOfVTable may return 0 if asked to get an address of a vtable which
1810 // shouldn't be used in the given record type. We want to cache this result in
1811 // VFTablesMap, thus a simple zero check is not sufficient.
1812
1813 VFTableIdTy ID(RD, VPtrOffset);
1814 VTablesMapTy::iterator I;
1815 bool Inserted;
1816 std::tie(I, Inserted) = VTablesMap.insert(std::make_pair(ID, nullptr));
1817 if (!Inserted)
1818 return I->second;
1819
1820 llvm::GlobalVariable *&VTable = I->second;
1821
1822 MicrosoftVTableContext &VTContext = CGM.getMicrosoftVTableContext();
1823 const VPtrInfoVector &VFPtrs = VTContext.getVFPtrOffsets(RD);
1824
1825 if (DeferredVFTables.insert(RD).second) {
1826 // We haven't processed this record type before.
1827 // Queue up this vtable for possible deferred emission.
1828 CGM.addDeferredVTable(RD);
1829
1830 #ifndef NDEBUG
1831 // Create all the vftables at once in order to make sure each vftable has
1832 // a unique mangled name.
1833 llvm::StringSet<> ObservedMangledNames;
1834 for (size_t J = 0, F = VFPtrs.size(); J != F; ++J) {
1835 SmallString<256> Name;
1836 mangleVFTableName(getMangleContext(), RD, *VFPtrs[J], Name);
1837 if (!ObservedMangledNames.insert(Name.str()).second)
1838 llvm_unreachable("Already saw this mangling before?");
1839 }
1840 #endif
1841 }
1842
1843 const std::unique_ptr<VPtrInfo> *VFPtrI =
1844 llvm::find_if(VFPtrs, [&](const std::unique_ptr<VPtrInfo> &VPI) {
1845 return VPI->FullOffsetInMDC == VPtrOffset;
1846 });
1847 if (VFPtrI == VFPtrs.end()) {
1848 VFTablesMap[ID] = nullptr;
1849 return nullptr;
1850 }
1851 const std::unique_ptr<VPtrInfo> &VFPtr = *VFPtrI;
1852
1853 SmallString<256> VFTableName;
1854 mangleVFTableName(getMangleContext(), RD, *VFPtr, VFTableName);
1855
1856 // Classes marked __declspec(dllimport) need vftables generated on the
1857 // import-side in order to support features like constexpr. No other
1858 // translation unit relies on the emission of the local vftable, translation
1859 // units are expected to generate them as needed.
1860 //
1861 // Because of this unique behavior, we maintain this logic here instead of
1862 // getVTableLinkage.
1863 llvm::GlobalValue::LinkageTypes VFTableLinkage =
1864 RD->hasAttr<DLLImportAttr>() ? llvm::GlobalValue::LinkOnceODRLinkage
1865 : CGM.getVTableLinkage(RD);
1866 bool VFTableComesFromAnotherTU =
1867 llvm::GlobalValue::isAvailableExternallyLinkage(VFTableLinkage) ||
1868 llvm::GlobalValue::isExternalLinkage(VFTableLinkage);
1869 bool VTableAliasIsRequred =
1870 !VFTableComesFromAnotherTU && getContext().getLangOpts().RTTIData;
1871
1872 if (llvm::GlobalValue *VFTable =
1873 CGM.getModule().getNamedGlobal(VFTableName)) {
1874 VFTablesMap[ID] = VFTable;
1875 VTable = VTableAliasIsRequred
1876 ? cast<llvm::GlobalVariable>(
1877 cast<llvm::GlobalAlias>(VFTable)->getAliaseeObject())
1878 : cast<llvm::GlobalVariable>(VFTable);
1879 return VTable;
1880 }
1881
1882 const VTableLayout &VTLayout =
1883 VTContext.getVFTableLayout(RD, VFPtr->FullOffsetInMDC);
1884 llvm::GlobalValue::LinkageTypes VTableLinkage =
1885 VTableAliasIsRequred ? llvm::GlobalValue::PrivateLinkage : VFTableLinkage;
1886
1887 StringRef VTableName = VTableAliasIsRequred ? StringRef() : VFTableName.str();
1888
1889 llvm::Type *VTableType = CGM.getVTables().getVTableType(VTLayout);
1890
1891 // Create a backing variable for the contents of VTable. The VTable may
1892 // or may not include space for a pointer to RTTI data.
1893 llvm::GlobalValue *VFTable;
1894 VTable = new llvm::GlobalVariable(CGM.getModule(), VTableType,
1895 /*isConstant=*/true, VTableLinkage,
1896 /*Initializer=*/nullptr, VTableName);
1897 VTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
1898
1899 llvm::Comdat *C = nullptr;
1900 if (!VFTableComesFromAnotherTU &&
1901 llvm::GlobalValue::isWeakForLinker(VFTableLinkage))
1902 C = CGM.getModule().getOrInsertComdat(VFTableName.str());
1903
1904 // Only insert a pointer into the VFTable for RTTI data if we are not
1905 // importing it. We never reference the RTTI data directly so there is no
1906 // need to make room for it.
1907 if (VTableAliasIsRequred) {
1908 llvm::Value *GEPIndices[] = {llvm::ConstantInt::get(CGM.Int32Ty, 0),
1909 llvm::ConstantInt::get(CGM.Int32Ty, 0),
1910 llvm::ConstantInt::get(CGM.Int32Ty, 1)};
1911 // Create a GEP which points just after the first entry in the VFTable,
1912 // this should be the location of the first virtual method.
1913 llvm::Constant *VTableGEP = llvm::ConstantExpr::getInBoundsGetElementPtr(
1914 VTable->getValueType(), VTable, GEPIndices);
1915 if (llvm::GlobalValue::isWeakForLinker(VFTableLinkage)) {
1916 VFTableLinkage = llvm::GlobalValue::ExternalLinkage;
1917 if (C)
1918 C->setSelectionKind(llvm::Comdat::Largest);
1919 }
1920 VFTable = llvm::GlobalAlias::create(CGM.Int8PtrTy,
1921 /*AddressSpace=*/0, VFTableLinkage,
1922 VFTableName.str(), VTableGEP,
1923 &CGM.getModule());
1924 VFTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
1925 } else {
1926 // We don't need a GlobalAlias to be a symbol for the VTable if we won't
1927 // be referencing any RTTI data.
1928 // The GlobalVariable will end up being an appropriate definition of the
1929 // VFTable.
1930 VFTable = VTable;
1931 }
1932 if (C)
1933 VTable->setComdat(C);
1934
1935 if (RD->hasAttr<DLLExportAttr>())
1936 VFTable->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);
1937
1938 VFTablesMap[ID] = VFTable;
1939 return VTable;
1940 }
1941
getVirtualFunctionPointer(CodeGenFunction & CGF,GlobalDecl GD,Address This,llvm::Type * Ty,SourceLocation Loc)1942 CGCallee MicrosoftCXXABI::getVirtualFunctionPointer(CodeGenFunction &CGF,
1943 GlobalDecl GD,
1944 Address This,
1945 llvm::Type *Ty,
1946 SourceLocation Loc) {
1947 CGBuilderTy &Builder = CGF.Builder;
1948
1949 Ty = Ty->getPointerTo();
1950 Address VPtr =
1951 adjustThisArgumentForVirtualFunctionCall(CGF, GD, This, true);
1952
1953 auto *MethodDecl = cast<CXXMethodDecl>(GD.getDecl());
1954 llvm::Value *VTable = CGF.GetVTablePtr(VPtr, Ty->getPointerTo(),
1955 MethodDecl->getParent());
1956
1957 MicrosoftVTableContext &VFTContext = CGM.getMicrosoftVTableContext();
1958 MethodVFTableLocation ML = VFTContext.getMethodVFTableLocation(GD);
1959
1960 // Compute the identity of the most derived class whose virtual table is
1961 // located at the MethodVFTableLocation ML.
1962 auto getObjectWithVPtr = [&] {
1963 return llvm::find_if(VFTContext.getVFPtrOffsets(
1964 ML.VBase ? ML.VBase : MethodDecl->getParent()),
1965 [&](const std::unique_ptr<VPtrInfo> &Info) {
1966 return Info->FullOffsetInMDC == ML.VFPtrOffset;
1967 })
1968 ->get()
1969 ->ObjectWithVPtr;
1970 };
1971
1972 llvm::Value *VFunc;
1973 if (CGF.ShouldEmitVTableTypeCheckedLoad(MethodDecl->getParent())) {
1974 VFunc = CGF.EmitVTableTypeCheckedLoad(
1975 getObjectWithVPtr(), VTable, Ty,
1976 ML.Index *
1977 CGM.getContext().getTargetInfo().getPointerWidth(LangAS::Default) /
1978 8);
1979 } else {
1980 if (CGM.getCodeGenOpts().PrepareForLTO)
1981 CGF.EmitTypeMetadataCodeForVCall(getObjectWithVPtr(), VTable, Loc);
1982
1983 llvm::Value *VFuncPtr =
1984 Builder.CreateConstInBoundsGEP1_64(Ty, VTable, ML.Index, "vfn");
1985 VFunc = Builder.CreateAlignedLoad(Ty, VFuncPtr, CGF.getPointerAlign());
1986 }
1987
1988 CGCallee Callee(GD, VFunc);
1989 return Callee;
1990 }
1991
EmitVirtualDestructorCall(CodeGenFunction & CGF,const CXXDestructorDecl * Dtor,CXXDtorType DtorType,Address This,DeleteOrMemberCallExpr E)1992 llvm::Value *MicrosoftCXXABI::EmitVirtualDestructorCall(
1993 CodeGenFunction &CGF, const CXXDestructorDecl *Dtor, CXXDtorType DtorType,
1994 Address This, DeleteOrMemberCallExpr E) {
1995 auto *CE = E.dyn_cast<const CXXMemberCallExpr *>();
1996 auto *D = E.dyn_cast<const CXXDeleteExpr *>();
1997 assert((CE != nullptr) ^ (D != nullptr));
1998 assert(CE == nullptr || CE->arg_begin() == CE->arg_end());
1999 assert(DtorType == Dtor_Deleting || DtorType == Dtor_Complete);
2000
2001 // We have only one destructor in the vftable but can get both behaviors
2002 // by passing an implicit int parameter.
2003 GlobalDecl GD(Dtor, Dtor_Deleting);
2004 const CGFunctionInfo *FInfo =
2005 &CGM.getTypes().arrangeCXXStructorDeclaration(GD);
2006 llvm::FunctionType *Ty = CGF.CGM.getTypes().GetFunctionType(*FInfo);
2007 CGCallee Callee = CGCallee::forVirtual(CE, GD, This, Ty);
2008
2009 ASTContext &Context = getContext();
2010 llvm::Value *ImplicitParam = llvm::ConstantInt::get(
2011 llvm::IntegerType::getInt32Ty(CGF.getLLVMContext()),
2012 DtorType == Dtor_Deleting);
2013
2014 QualType ThisTy;
2015 if (CE) {
2016 ThisTy = CE->getObjectType();
2017 } else {
2018 ThisTy = D->getDestroyedType();
2019 }
2020
2021 This = adjustThisArgumentForVirtualFunctionCall(CGF, GD, This, true);
2022 RValue RV = CGF.EmitCXXDestructorCall(GD, Callee, This.getPointer(), ThisTy,
2023 ImplicitParam, Context.IntTy, CE);
2024 return RV.getScalarVal();
2025 }
2026
2027 const VBTableGlobals &
enumerateVBTables(const CXXRecordDecl * RD)2028 MicrosoftCXXABI::enumerateVBTables(const CXXRecordDecl *RD) {
2029 // At this layer, we can key the cache off of a single class, which is much
2030 // easier than caching each vbtable individually.
2031 llvm::DenseMap<const CXXRecordDecl*, VBTableGlobals>::iterator Entry;
2032 bool Added;
2033 std::tie(Entry, Added) =
2034 VBTablesMap.insert(std::make_pair(RD, VBTableGlobals()));
2035 VBTableGlobals &VBGlobals = Entry->second;
2036 if (!Added)
2037 return VBGlobals;
2038
2039 MicrosoftVTableContext &Context = CGM.getMicrosoftVTableContext();
2040 VBGlobals.VBTables = &Context.enumerateVBTables(RD);
2041
2042 // Cache the globals for all vbtables so we don't have to recompute the
2043 // mangled names.
2044 llvm::GlobalVariable::LinkageTypes Linkage = CGM.getVTableLinkage(RD);
2045 for (VPtrInfoVector::const_iterator I = VBGlobals.VBTables->begin(),
2046 E = VBGlobals.VBTables->end();
2047 I != E; ++I) {
2048 VBGlobals.Globals.push_back(getAddrOfVBTable(**I, RD, Linkage));
2049 }
2050
2051 return VBGlobals;
2052 }
2053
2054 llvm::Function *
EmitVirtualMemPtrThunk(const CXXMethodDecl * MD,const MethodVFTableLocation & ML)2055 MicrosoftCXXABI::EmitVirtualMemPtrThunk(const CXXMethodDecl *MD,
2056 const MethodVFTableLocation &ML) {
2057 assert(!isa<CXXConstructorDecl>(MD) && !isa<CXXDestructorDecl>(MD) &&
2058 "can't form pointers to ctors or virtual dtors");
2059
2060 // Calculate the mangled name.
2061 SmallString<256> ThunkName;
2062 llvm::raw_svector_ostream Out(ThunkName);
2063 getMangleContext().mangleVirtualMemPtrThunk(MD, ML, Out);
2064
2065 // If the thunk has been generated previously, just return it.
2066 if (llvm::GlobalValue *GV = CGM.getModule().getNamedValue(ThunkName))
2067 return cast<llvm::Function>(GV);
2068
2069 // Create the llvm::Function.
2070 const CGFunctionInfo &FnInfo =
2071 CGM.getTypes().arrangeUnprototypedMustTailThunk(MD);
2072 llvm::FunctionType *ThunkTy = CGM.getTypes().GetFunctionType(FnInfo);
2073 llvm::Function *ThunkFn =
2074 llvm::Function::Create(ThunkTy, llvm::Function::ExternalLinkage,
2075 ThunkName.str(), &CGM.getModule());
2076 assert(ThunkFn->getName() == ThunkName && "name was uniqued!");
2077
2078 ThunkFn->setLinkage(MD->isExternallyVisible()
2079 ? llvm::GlobalValue::LinkOnceODRLinkage
2080 : llvm::GlobalValue::InternalLinkage);
2081 if (MD->isExternallyVisible())
2082 ThunkFn->setComdat(CGM.getModule().getOrInsertComdat(ThunkFn->getName()));
2083
2084 CGM.SetLLVMFunctionAttributes(MD, FnInfo, ThunkFn, /*IsThunk=*/false);
2085 CGM.SetLLVMFunctionAttributesForDefinition(MD, ThunkFn);
2086
2087 // Add the "thunk" attribute so that LLVM knows that the return type is
2088 // meaningless. These thunks can be used to call functions with differing
2089 // return types, and the caller is required to cast the prototype
2090 // appropriately to extract the correct value.
2091 ThunkFn->addFnAttr("thunk");
2092
2093 // These thunks can be compared, so they are not unnamed.
2094 ThunkFn->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::None);
2095
2096 // Start codegen.
2097 CodeGenFunction CGF(CGM);
2098 CGF.CurGD = GlobalDecl(MD);
2099 CGF.CurFuncIsThunk = true;
2100
2101 // Build FunctionArgs, but only include the implicit 'this' parameter
2102 // declaration.
2103 FunctionArgList FunctionArgs;
2104 buildThisParam(CGF, FunctionArgs);
2105
2106 // Start defining the function.
2107 CGF.StartFunction(GlobalDecl(), FnInfo.getReturnType(), ThunkFn, FnInfo,
2108 FunctionArgs, MD->getLocation(), SourceLocation());
2109
2110 ApplyDebugLocation AL(CGF, MD->getLocation());
2111 setCXXABIThisValue(CGF, loadIncomingCXXThis(CGF));
2112
2113 // Load the vfptr and then callee from the vftable. The callee should have
2114 // adjusted 'this' so that the vfptr is at offset zero.
2115 llvm::Type *ThunkPtrTy = ThunkTy->getPointerTo();
2116 llvm::Value *VTable = CGF.GetVTablePtr(
2117 getThisAddress(CGF), ThunkPtrTy->getPointerTo(), MD->getParent());
2118
2119 llvm::Value *VFuncPtr = CGF.Builder.CreateConstInBoundsGEP1_64(
2120 ThunkPtrTy, VTable, ML.Index, "vfn");
2121 llvm::Value *Callee =
2122 CGF.Builder.CreateAlignedLoad(ThunkPtrTy, VFuncPtr, CGF.getPointerAlign());
2123
2124 CGF.EmitMustTailThunk(MD, getThisValue(CGF), {ThunkTy, Callee});
2125
2126 return ThunkFn;
2127 }
2128
emitVirtualInheritanceTables(const CXXRecordDecl * RD)2129 void MicrosoftCXXABI::emitVirtualInheritanceTables(const CXXRecordDecl *RD) {
2130 const VBTableGlobals &VBGlobals = enumerateVBTables(RD);
2131 for (unsigned I = 0, E = VBGlobals.VBTables->size(); I != E; ++I) {
2132 const std::unique_ptr<VPtrInfo>& VBT = (*VBGlobals.VBTables)[I];
2133 llvm::GlobalVariable *GV = VBGlobals.Globals[I];
2134 if (GV->isDeclaration())
2135 emitVBTableDefinition(*VBT, RD, GV);
2136 }
2137 }
2138
2139 llvm::GlobalVariable *
getAddrOfVBTable(const VPtrInfo & VBT,const CXXRecordDecl * RD,llvm::GlobalVariable::LinkageTypes Linkage)2140 MicrosoftCXXABI::getAddrOfVBTable(const VPtrInfo &VBT, const CXXRecordDecl *RD,
2141 llvm::GlobalVariable::LinkageTypes Linkage) {
2142 SmallString<256> OutName;
2143 llvm::raw_svector_ostream Out(OutName);
2144 getMangleContext().mangleCXXVBTable(RD, VBT.MangledPath, Out);
2145 StringRef Name = OutName.str();
2146
2147 llvm::ArrayType *VBTableType =
2148 llvm::ArrayType::get(CGM.IntTy, 1 + VBT.ObjectWithVPtr->getNumVBases());
2149
2150 assert(!CGM.getModule().getNamedGlobal(Name) &&
2151 "vbtable with this name already exists: mangling bug?");
2152 CharUnits Alignment =
2153 CGM.getContext().getTypeAlignInChars(CGM.getContext().IntTy);
2154 llvm::GlobalVariable *GV = CGM.CreateOrReplaceCXXRuntimeVariable(
2155 Name, VBTableType, Linkage, Alignment.getAsAlign());
2156 GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
2157
2158 if (RD->hasAttr<DLLImportAttr>())
2159 GV->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass);
2160 else if (RD->hasAttr<DLLExportAttr>())
2161 GV->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);
2162
2163 if (!GV->hasExternalLinkage())
2164 emitVBTableDefinition(VBT, RD, GV);
2165
2166 return GV;
2167 }
2168
emitVBTableDefinition(const VPtrInfo & VBT,const CXXRecordDecl * RD,llvm::GlobalVariable * GV) const2169 void MicrosoftCXXABI::emitVBTableDefinition(const VPtrInfo &VBT,
2170 const CXXRecordDecl *RD,
2171 llvm::GlobalVariable *GV) const {
2172 const CXXRecordDecl *ObjectWithVPtr = VBT.ObjectWithVPtr;
2173
2174 assert(RD->getNumVBases() && ObjectWithVPtr->getNumVBases() &&
2175 "should only emit vbtables for classes with vbtables");
2176
2177 const ASTRecordLayout &BaseLayout =
2178 getContext().getASTRecordLayout(VBT.IntroducingObject);
2179 const ASTRecordLayout &DerivedLayout = getContext().getASTRecordLayout(RD);
2180
2181 SmallVector<llvm::Constant *, 4> Offsets(1 + ObjectWithVPtr->getNumVBases(),
2182 nullptr);
2183
2184 // The offset from ObjectWithVPtr's vbptr to itself always leads.
2185 CharUnits VBPtrOffset = BaseLayout.getVBPtrOffset();
2186 Offsets[0] = llvm::ConstantInt::get(CGM.IntTy, -VBPtrOffset.getQuantity());
2187
2188 MicrosoftVTableContext &Context = CGM.getMicrosoftVTableContext();
2189 for (const auto &I : ObjectWithVPtr->vbases()) {
2190 const CXXRecordDecl *VBase = I.getType()->getAsCXXRecordDecl();
2191 CharUnits Offset = DerivedLayout.getVBaseClassOffset(VBase);
2192 assert(!Offset.isNegative());
2193
2194 // Make it relative to the subobject vbptr.
2195 CharUnits CompleteVBPtrOffset = VBT.NonVirtualOffset + VBPtrOffset;
2196 if (VBT.getVBaseWithVPtr())
2197 CompleteVBPtrOffset +=
2198 DerivedLayout.getVBaseClassOffset(VBT.getVBaseWithVPtr());
2199 Offset -= CompleteVBPtrOffset;
2200
2201 unsigned VBIndex = Context.getVBTableIndex(ObjectWithVPtr, VBase);
2202 assert(Offsets[VBIndex] == nullptr && "The same vbindex seen twice?");
2203 Offsets[VBIndex] = llvm::ConstantInt::get(CGM.IntTy, Offset.getQuantity());
2204 }
2205
2206 assert(Offsets.size() ==
2207 cast<llvm::ArrayType>(GV->getValueType())->getNumElements());
2208 llvm::ArrayType *VBTableType =
2209 llvm::ArrayType::get(CGM.IntTy, Offsets.size());
2210 llvm::Constant *Init = llvm::ConstantArray::get(VBTableType, Offsets);
2211 GV->setInitializer(Init);
2212
2213 if (RD->hasAttr<DLLImportAttr>())
2214 GV->setLinkage(llvm::GlobalVariable::AvailableExternallyLinkage);
2215 }
2216
performThisAdjustment(CodeGenFunction & CGF,Address This,const ThisAdjustment & TA)2217 llvm::Value *MicrosoftCXXABI::performThisAdjustment(CodeGenFunction &CGF,
2218 Address This,
2219 const ThisAdjustment &TA) {
2220 if (TA.isEmpty())
2221 return This.getPointer();
2222
2223 This = This.withElementType(CGF.Int8Ty);
2224
2225 llvm::Value *V;
2226 if (TA.Virtual.isEmpty()) {
2227 V = This.getPointer();
2228 } else {
2229 assert(TA.Virtual.Microsoft.VtordispOffset < 0);
2230 // Adjust the this argument based on the vtordisp value.
2231 Address VtorDispPtr =
2232 CGF.Builder.CreateConstInBoundsByteGEP(This,
2233 CharUnits::fromQuantity(TA.Virtual.Microsoft.VtordispOffset));
2234 VtorDispPtr = VtorDispPtr.withElementType(CGF.Int32Ty);
2235 llvm::Value *VtorDisp = CGF.Builder.CreateLoad(VtorDispPtr, "vtordisp");
2236 V = CGF.Builder.CreateGEP(This.getElementType(), This.getPointer(),
2237 CGF.Builder.CreateNeg(VtorDisp));
2238
2239 // Unfortunately, having applied the vtordisp means that we no
2240 // longer really have a known alignment for the vbptr step.
2241 // We'll assume the vbptr is pointer-aligned.
2242
2243 if (TA.Virtual.Microsoft.VBPtrOffset) {
2244 // If the final overrider is defined in a virtual base other than the one
2245 // that holds the vfptr, we have to use a vtordispex thunk which looks up
2246 // the vbtable of the derived class.
2247 assert(TA.Virtual.Microsoft.VBPtrOffset > 0);
2248 assert(TA.Virtual.Microsoft.VBOffsetOffset >= 0);
2249 llvm::Value *VBPtr;
2250 llvm::Value *VBaseOffset = GetVBaseOffsetFromVBPtr(
2251 CGF, Address(V, CGF.Int8Ty, CGF.getPointerAlign()),
2252 -TA.Virtual.Microsoft.VBPtrOffset,
2253 TA.Virtual.Microsoft.VBOffsetOffset, &VBPtr);
2254 V = CGF.Builder.CreateInBoundsGEP(CGF.Int8Ty, VBPtr, VBaseOffset);
2255 }
2256 }
2257
2258 if (TA.NonVirtual) {
2259 // Non-virtual adjustment might result in a pointer outside the allocated
2260 // object, e.g. if the final overrider class is laid out after the virtual
2261 // base that declares a method in the most derived class.
2262 V = CGF.Builder.CreateConstGEP1_32(CGF.Int8Ty, V, TA.NonVirtual);
2263 }
2264
2265 // Don't need to bitcast back, the call CodeGen will handle this.
2266 return V;
2267 }
2268
2269 llvm::Value *
performReturnAdjustment(CodeGenFunction & CGF,Address Ret,const ReturnAdjustment & RA)2270 MicrosoftCXXABI::performReturnAdjustment(CodeGenFunction &CGF, Address Ret,
2271 const ReturnAdjustment &RA) {
2272 if (RA.isEmpty())
2273 return Ret.getPointer();
2274
2275 Ret = Ret.withElementType(CGF.Int8Ty);
2276
2277 llvm::Value *V = Ret.getPointer();
2278 if (RA.Virtual.Microsoft.VBIndex) {
2279 assert(RA.Virtual.Microsoft.VBIndex > 0);
2280 int32_t IntSize = CGF.getIntSize().getQuantity();
2281 llvm::Value *VBPtr;
2282 llvm::Value *VBaseOffset =
2283 GetVBaseOffsetFromVBPtr(CGF, Ret, RA.Virtual.Microsoft.VBPtrOffset,
2284 IntSize * RA.Virtual.Microsoft.VBIndex, &VBPtr);
2285 V = CGF.Builder.CreateInBoundsGEP(CGF.Int8Ty, VBPtr, VBaseOffset);
2286 }
2287
2288 if (RA.NonVirtual)
2289 V = CGF.Builder.CreateConstInBoundsGEP1_32(CGF.Int8Ty, V, RA.NonVirtual);
2290
2291 return V;
2292 }
2293
requiresArrayCookie(const CXXDeleteExpr * expr,QualType elementType)2294 bool MicrosoftCXXABI::requiresArrayCookie(const CXXDeleteExpr *expr,
2295 QualType elementType) {
2296 // Microsoft seems to completely ignore the possibility of a
2297 // two-argument usual deallocation function.
2298 return elementType.isDestructedType();
2299 }
2300
requiresArrayCookie(const CXXNewExpr * expr)2301 bool MicrosoftCXXABI::requiresArrayCookie(const CXXNewExpr *expr) {
2302 // Microsoft seems to completely ignore the possibility of a
2303 // two-argument usual deallocation function.
2304 return expr->getAllocatedType().isDestructedType();
2305 }
2306
getArrayCookieSizeImpl(QualType type)2307 CharUnits MicrosoftCXXABI::getArrayCookieSizeImpl(QualType type) {
2308 // The array cookie is always a size_t; we then pad that out to the
2309 // alignment of the element type.
2310 ASTContext &Ctx = getContext();
2311 return std::max(Ctx.getTypeSizeInChars(Ctx.getSizeType()),
2312 Ctx.getTypeAlignInChars(type));
2313 }
2314
readArrayCookieImpl(CodeGenFunction & CGF,Address allocPtr,CharUnits cookieSize)2315 llvm::Value *MicrosoftCXXABI::readArrayCookieImpl(CodeGenFunction &CGF,
2316 Address allocPtr,
2317 CharUnits cookieSize) {
2318 Address numElementsPtr = allocPtr.withElementType(CGF.SizeTy);
2319 return CGF.Builder.CreateLoad(numElementsPtr);
2320 }
2321
InitializeArrayCookie(CodeGenFunction & CGF,Address newPtr,llvm::Value * numElements,const CXXNewExpr * expr,QualType elementType)2322 Address MicrosoftCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,
2323 Address newPtr,
2324 llvm::Value *numElements,
2325 const CXXNewExpr *expr,
2326 QualType elementType) {
2327 assert(requiresArrayCookie(expr));
2328
2329 // The size of the cookie.
2330 CharUnits cookieSize = getArrayCookieSizeImpl(elementType);
2331
2332 // Compute an offset to the cookie.
2333 Address cookiePtr = newPtr;
2334
2335 // Write the number of elements into the appropriate slot.
2336 Address numElementsPtr = cookiePtr.withElementType(CGF.SizeTy);
2337 CGF.Builder.CreateStore(numElements, numElementsPtr);
2338
2339 // Finally, compute a pointer to the actual data buffer by skipping
2340 // over the cookie completely.
2341 return CGF.Builder.CreateConstInBoundsByteGEP(newPtr, cookieSize);
2342 }
2343
emitGlobalDtorWithTLRegDtor(CodeGenFunction & CGF,const VarDecl & VD,llvm::FunctionCallee Dtor,llvm::Constant * Addr)2344 static void emitGlobalDtorWithTLRegDtor(CodeGenFunction &CGF, const VarDecl &VD,
2345 llvm::FunctionCallee Dtor,
2346 llvm::Constant *Addr) {
2347 // Create a function which calls the destructor.
2348 llvm::Constant *DtorStub = CGF.createAtExitStub(VD, Dtor, Addr);
2349
2350 // extern "C" int __tlregdtor(void (*f)(void));
2351 llvm::FunctionType *TLRegDtorTy = llvm::FunctionType::get(
2352 CGF.IntTy, DtorStub->getType(), /*isVarArg=*/false);
2353
2354 llvm::FunctionCallee TLRegDtor = CGF.CGM.CreateRuntimeFunction(
2355 TLRegDtorTy, "__tlregdtor", llvm::AttributeList(), /*Local=*/true);
2356 if (llvm::Function *TLRegDtorFn =
2357 dyn_cast<llvm::Function>(TLRegDtor.getCallee()))
2358 TLRegDtorFn->setDoesNotThrow();
2359
2360 CGF.EmitNounwindRuntimeCall(TLRegDtor, DtorStub);
2361 }
2362
registerGlobalDtor(CodeGenFunction & CGF,const VarDecl & D,llvm::FunctionCallee Dtor,llvm::Constant * Addr)2363 void MicrosoftCXXABI::registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,
2364 llvm::FunctionCallee Dtor,
2365 llvm::Constant *Addr) {
2366 if (D.isNoDestroy(CGM.getContext()))
2367 return;
2368
2369 if (D.getTLSKind())
2370 return emitGlobalDtorWithTLRegDtor(CGF, D, Dtor, Addr);
2371
2372 // HLSL doesn't support atexit.
2373 if (CGM.getLangOpts().HLSL)
2374 return CGM.AddCXXDtorEntry(Dtor, Addr);
2375
2376 // The default behavior is to use atexit.
2377 CGF.registerGlobalDtorWithAtExit(D, Dtor, Addr);
2378 }
2379
EmitThreadLocalInitFuncs(CodeGenModule & CGM,ArrayRef<const VarDecl * > CXXThreadLocals,ArrayRef<llvm::Function * > CXXThreadLocalInits,ArrayRef<const VarDecl * > CXXThreadLocalInitVars)2380 void MicrosoftCXXABI::EmitThreadLocalInitFuncs(
2381 CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals,
2382 ArrayRef<llvm::Function *> CXXThreadLocalInits,
2383 ArrayRef<const VarDecl *> CXXThreadLocalInitVars) {
2384 if (CXXThreadLocalInits.empty())
2385 return;
2386
2387 CGM.AppendLinkerOptions(CGM.getTarget().getTriple().getArch() ==
2388 llvm::Triple::x86
2389 ? "/include:___dyn_tls_init@12"
2390 : "/include:__dyn_tls_init");
2391
2392 // This will create a GV in the .CRT$XDU section. It will point to our
2393 // initialization function. The CRT will call all of these function
2394 // pointers at start-up time and, eventually, at thread-creation time.
2395 auto AddToXDU = [&CGM](llvm::Function *InitFunc) {
2396 llvm::GlobalVariable *InitFuncPtr = new llvm::GlobalVariable(
2397 CGM.getModule(), InitFunc->getType(), /*isConstant=*/true,
2398 llvm::GlobalVariable::InternalLinkage, InitFunc,
2399 Twine(InitFunc->getName(), "$initializer$"));
2400 InitFuncPtr->setSection(".CRT$XDU");
2401 // This variable has discardable linkage, we have to add it to @llvm.used to
2402 // ensure it won't get discarded.
2403 CGM.addUsedGlobal(InitFuncPtr);
2404 return InitFuncPtr;
2405 };
2406
2407 std::vector<llvm::Function *> NonComdatInits;
2408 for (size_t I = 0, E = CXXThreadLocalInitVars.size(); I != E; ++I) {
2409 llvm::GlobalVariable *GV = cast<llvm::GlobalVariable>(
2410 CGM.GetGlobalValue(CGM.getMangledName(CXXThreadLocalInitVars[I])));
2411 llvm::Function *F = CXXThreadLocalInits[I];
2412
2413 // If the GV is already in a comdat group, then we have to join it.
2414 if (llvm::Comdat *C = GV->getComdat())
2415 AddToXDU(F)->setComdat(C);
2416 else
2417 NonComdatInits.push_back(F);
2418 }
2419
2420 if (!NonComdatInits.empty()) {
2421 llvm::FunctionType *FTy =
2422 llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false);
2423 llvm::Function *InitFunc = CGM.CreateGlobalInitOrCleanUpFunction(
2424 FTy, "__tls_init", CGM.getTypes().arrangeNullaryFunction(),
2425 SourceLocation(), /*TLS=*/true);
2426 CodeGenFunction(CGM).GenerateCXXGlobalInitFunc(InitFunc, NonComdatInits);
2427
2428 AddToXDU(InitFunc);
2429 }
2430 }
2431
getTlsGuardVar(CodeGenModule & CGM)2432 static llvm::GlobalValue *getTlsGuardVar(CodeGenModule &CGM) {
2433 // __tls_guard comes from the MSVC runtime and reflects
2434 // whether TLS has been initialized for a particular thread.
2435 // It is set from within __dyn_tls_init by the runtime.
2436 // Every library and executable has its own variable.
2437 llvm::Type *VTy = llvm::Type::getInt8Ty(CGM.getLLVMContext());
2438 llvm::Constant *TlsGuardConstant =
2439 CGM.CreateRuntimeVariable(VTy, "__tls_guard");
2440 llvm::GlobalValue *TlsGuard = cast<llvm::GlobalValue>(TlsGuardConstant);
2441
2442 TlsGuard->setThreadLocal(true);
2443
2444 return TlsGuard;
2445 }
2446
getDynTlsOnDemandInitFn(CodeGenModule & CGM)2447 static llvm::FunctionCallee getDynTlsOnDemandInitFn(CodeGenModule &CGM) {
2448 // __dyn_tls_on_demand_init comes from the MSVC runtime and triggers
2449 // dynamic TLS initialization by calling __dyn_tls_init internally.
2450 llvm::FunctionType *FTy =
2451 llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()), {},
2452 /*isVarArg=*/false);
2453 return CGM.CreateRuntimeFunction(
2454 FTy, "__dyn_tls_on_demand_init",
2455 llvm::AttributeList::get(CGM.getLLVMContext(),
2456 llvm::AttributeList::FunctionIndex,
2457 llvm::Attribute::NoUnwind),
2458 /*Local=*/true);
2459 }
2460
emitTlsGuardCheck(CodeGenFunction & CGF,llvm::GlobalValue * TlsGuard,llvm::BasicBlock * DynInitBB,llvm::BasicBlock * ContinueBB)2461 static void emitTlsGuardCheck(CodeGenFunction &CGF, llvm::GlobalValue *TlsGuard,
2462 llvm::BasicBlock *DynInitBB,
2463 llvm::BasicBlock *ContinueBB) {
2464 llvm::LoadInst *TlsGuardValue =
2465 CGF.Builder.CreateLoad(Address(TlsGuard, CGF.Int8Ty, CharUnits::One()));
2466 llvm::Value *CmpResult =
2467 CGF.Builder.CreateICmpEQ(TlsGuardValue, CGF.Builder.getInt8(0));
2468 CGF.Builder.CreateCondBr(CmpResult, DynInitBB, ContinueBB);
2469 }
2470
emitDynamicTlsInitializationCall(CodeGenFunction & CGF,llvm::GlobalValue * TlsGuard,llvm::BasicBlock * ContinueBB)2471 static void emitDynamicTlsInitializationCall(CodeGenFunction &CGF,
2472 llvm::GlobalValue *TlsGuard,
2473 llvm::BasicBlock *ContinueBB) {
2474 llvm::FunctionCallee Initializer = getDynTlsOnDemandInitFn(CGF.CGM);
2475 llvm::Function *InitializerFunction =
2476 cast<llvm::Function>(Initializer.getCallee());
2477 llvm::CallInst *CallVal = CGF.Builder.CreateCall(InitializerFunction);
2478 CallVal->setCallingConv(InitializerFunction->getCallingConv());
2479
2480 CGF.Builder.CreateBr(ContinueBB);
2481 }
2482
emitDynamicTlsInitialization(CodeGenFunction & CGF)2483 static void emitDynamicTlsInitialization(CodeGenFunction &CGF) {
2484 llvm::BasicBlock *DynInitBB =
2485 CGF.createBasicBlock("dyntls.dyn_init", CGF.CurFn);
2486 llvm::BasicBlock *ContinueBB =
2487 CGF.createBasicBlock("dyntls.continue", CGF.CurFn);
2488
2489 llvm::GlobalValue *TlsGuard = getTlsGuardVar(CGF.CGM);
2490
2491 emitTlsGuardCheck(CGF, TlsGuard, DynInitBB, ContinueBB);
2492 CGF.Builder.SetInsertPoint(DynInitBB);
2493 emitDynamicTlsInitializationCall(CGF, TlsGuard, ContinueBB);
2494 CGF.Builder.SetInsertPoint(ContinueBB);
2495 }
2496
EmitThreadLocalVarDeclLValue(CodeGenFunction & CGF,const VarDecl * VD,QualType LValType)2497 LValue MicrosoftCXXABI::EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF,
2498 const VarDecl *VD,
2499 QualType LValType) {
2500 // Dynamic TLS initialization works by checking the state of a
2501 // guard variable (__tls_guard) to see whether TLS initialization
2502 // for a thread has happend yet.
2503 // If not, the initialization is triggered on-demand
2504 // by calling __dyn_tls_on_demand_init.
2505 emitDynamicTlsInitialization(CGF);
2506
2507 // Emit the variable just like any regular global variable.
2508
2509 llvm::Value *V = CGF.CGM.GetAddrOfGlobalVar(VD);
2510 llvm::Type *RealVarTy = CGF.getTypes().ConvertTypeForMem(VD->getType());
2511
2512 CharUnits Alignment = CGF.getContext().getDeclAlign(VD);
2513 Address Addr(V, RealVarTy, Alignment);
2514
2515 LValue LV = VD->getType()->isReferenceType()
2516 ? CGF.EmitLoadOfReferenceLValue(Addr, VD->getType(),
2517 AlignmentSource::Decl)
2518 : CGF.MakeAddrLValue(Addr, LValType, AlignmentSource::Decl);
2519 return LV;
2520 }
2521
getInitThreadEpochPtr(CodeGenModule & CGM)2522 static ConstantAddress getInitThreadEpochPtr(CodeGenModule &CGM) {
2523 StringRef VarName("_Init_thread_epoch");
2524 CharUnits Align = CGM.getIntAlign();
2525 if (auto *GV = CGM.getModule().getNamedGlobal(VarName))
2526 return ConstantAddress(GV, GV->getValueType(), Align);
2527 auto *GV = new llvm::GlobalVariable(
2528 CGM.getModule(), CGM.IntTy,
2529 /*isConstant=*/false, llvm::GlobalVariable::ExternalLinkage,
2530 /*Initializer=*/nullptr, VarName,
2531 /*InsertBefore=*/nullptr, llvm::GlobalVariable::GeneralDynamicTLSModel);
2532 GV->setAlignment(Align.getAsAlign());
2533 return ConstantAddress(GV, GV->getValueType(), Align);
2534 }
2535
getInitThreadHeaderFn(CodeGenModule & CGM)2536 static llvm::FunctionCallee getInitThreadHeaderFn(CodeGenModule &CGM) {
2537 llvm::FunctionType *FTy =
2538 llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()),
2539 CGM.IntTy->getPointerTo(), /*isVarArg=*/false);
2540 return CGM.CreateRuntimeFunction(
2541 FTy, "_Init_thread_header",
2542 llvm::AttributeList::get(CGM.getLLVMContext(),
2543 llvm::AttributeList::FunctionIndex,
2544 llvm::Attribute::NoUnwind),
2545 /*Local=*/true);
2546 }
2547
getInitThreadFooterFn(CodeGenModule & CGM)2548 static llvm::FunctionCallee getInitThreadFooterFn(CodeGenModule &CGM) {
2549 llvm::FunctionType *FTy =
2550 llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()),
2551 CGM.IntTy->getPointerTo(), /*isVarArg=*/false);
2552 return CGM.CreateRuntimeFunction(
2553 FTy, "_Init_thread_footer",
2554 llvm::AttributeList::get(CGM.getLLVMContext(),
2555 llvm::AttributeList::FunctionIndex,
2556 llvm::Attribute::NoUnwind),
2557 /*Local=*/true);
2558 }
2559
getInitThreadAbortFn(CodeGenModule & CGM)2560 static llvm::FunctionCallee getInitThreadAbortFn(CodeGenModule &CGM) {
2561 llvm::FunctionType *FTy =
2562 llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()),
2563 CGM.IntTy->getPointerTo(), /*isVarArg=*/false);
2564 return CGM.CreateRuntimeFunction(
2565 FTy, "_Init_thread_abort",
2566 llvm::AttributeList::get(CGM.getLLVMContext(),
2567 llvm::AttributeList::FunctionIndex,
2568 llvm::Attribute::NoUnwind),
2569 /*Local=*/true);
2570 }
2571
2572 namespace {
2573 struct ResetGuardBit final : EHScopeStack::Cleanup {
2574 Address Guard;
2575 unsigned GuardNum;
ResetGuardBit__anond2fcd7db0711::ResetGuardBit2576 ResetGuardBit(Address Guard, unsigned GuardNum)
2577 : Guard(Guard), GuardNum(GuardNum) {}
2578
Emit__anond2fcd7db0711::ResetGuardBit2579 void Emit(CodeGenFunction &CGF, Flags flags) override {
2580 // Reset the bit in the mask so that the static variable may be
2581 // reinitialized.
2582 CGBuilderTy &Builder = CGF.Builder;
2583 llvm::LoadInst *LI = Builder.CreateLoad(Guard);
2584 llvm::ConstantInt *Mask =
2585 llvm::ConstantInt::get(CGF.IntTy, ~(1ULL << GuardNum));
2586 Builder.CreateStore(Builder.CreateAnd(LI, Mask), Guard);
2587 }
2588 };
2589
2590 struct CallInitThreadAbort final : EHScopeStack::Cleanup {
2591 llvm::Value *Guard;
CallInitThreadAbort__anond2fcd7db0711::CallInitThreadAbort2592 CallInitThreadAbort(Address Guard) : Guard(Guard.getPointer()) {}
2593
Emit__anond2fcd7db0711::CallInitThreadAbort2594 void Emit(CodeGenFunction &CGF, Flags flags) override {
2595 // Calling _Init_thread_abort will reset the guard's state.
2596 CGF.EmitNounwindRuntimeCall(getInitThreadAbortFn(CGF.CGM), Guard);
2597 }
2598 };
2599 }
2600
EmitGuardedInit(CodeGenFunction & CGF,const VarDecl & D,llvm::GlobalVariable * GV,bool PerformInit)2601 void MicrosoftCXXABI::EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
2602 llvm::GlobalVariable *GV,
2603 bool PerformInit) {
2604 // MSVC only uses guards for static locals.
2605 if (!D.isStaticLocal()) {
2606 assert(GV->hasWeakLinkage() || GV->hasLinkOnceLinkage());
2607 // GlobalOpt is allowed to discard the initializer, so use linkonce_odr.
2608 llvm::Function *F = CGF.CurFn;
2609 F->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage);
2610 F->setComdat(CGM.getModule().getOrInsertComdat(F->getName()));
2611 CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit);
2612 return;
2613 }
2614
2615 bool ThreadlocalStatic = D.getTLSKind();
2616 bool ThreadsafeStatic = getContext().getLangOpts().ThreadsafeStatics;
2617
2618 // Thread-safe static variables which aren't thread-specific have a
2619 // per-variable guard.
2620 bool HasPerVariableGuard = ThreadsafeStatic && !ThreadlocalStatic;
2621
2622 CGBuilderTy &Builder = CGF.Builder;
2623 llvm::IntegerType *GuardTy = CGF.Int32Ty;
2624 llvm::ConstantInt *Zero = llvm::ConstantInt::get(GuardTy, 0);
2625 CharUnits GuardAlign = CharUnits::fromQuantity(4);
2626
2627 // Get the guard variable for this function if we have one already.
2628 GuardInfo *GI = nullptr;
2629 if (ThreadlocalStatic)
2630 GI = &ThreadLocalGuardVariableMap[D.getDeclContext()];
2631 else if (!ThreadsafeStatic)
2632 GI = &GuardVariableMap[D.getDeclContext()];
2633
2634 llvm::GlobalVariable *GuardVar = GI ? GI->Guard : nullptr;
2635 unsigned GuardNum;
2636 if (D.isExternallyVisible()) {
2637 // Externally visible variables have to be numbered in Sema to properly
2638 // handle unreachable VarDecls.
2639 GuardNum = getContext().getStaticLocalNumber(&D);
2640 assert(GuardNum > 0);
2641 GuardNum--;
2642 } else if (HasPerVariableGuard) {
2643 GuardNum = ThreadSafeGuardNumMap[D.getDeclContext()]++;
2644 } else {
2645 // Non-externally visible variables are numbered here in CodeGen.
2646 GuardNum = GI->BitIndex++;
2647 }
2648
2649 if (!HasPerVariableGuard && GuardNum >= 32) {
2650 if (D.isExternallyVisible())
2651 ErrorUnsupportedABI(CGF, "more than 32 guarded initializations");
2652 GuardNum %= 32;
2653 GuardVar = nullptr;
2654 }
2655
2656 if (!GuardVar) {
2657 // Mangle the name for the guard.
2658 SmallString<256> GuardName;
2659 {
2660 llvm::raw_svector_ostream Out(GuardName);
2661 if (HasPerVariableGuard)
2662 getMangleContext().mangleThreadSafeStaticGuardVariable(&D, GuardNum,
2663 Out);
2664 else
2665 getMangleContext().mangleStaticGuardVariable(&D, Out);
2666 }
2667
2668 // Create the guard variable with a zero-initializer. Just absorb linkage,
2669 // visibility and dll storage class from the guarded variable.
2670 GuardVar =
2671 new llvm::GlobalVariable(CGM.getModule(), GuardTy, /*isConstant=*/false,
2672 GV->getLinkage(), Zero, GuardName.str());
2673 GuardVar->setVisibility(GV->getVisibility());
2674 GuardVar->setDLLStorageClass(GV->getDLLStorageClass());
2675 GuardVar->setAlignment(GuardAlign.getAsAlign());
2676 if (GuardVar->isWeakForLinker())
2677 GuardVar->setComdat(
2678 CGM.getModule().getOrInsertComdat(GuardVar->getName()));
2679 if (D.getTLSKind())
2680 CGM.setTLSMode(GuardVar, D);
2681 if (GI && !HasPerVariableGuard)
2682 GI->Guard = GuardVar;
2683 }
2684
2685 ConstantAddress GuardAddr(GuardVar, GuardTy, GuardAlign);
2686
2687 assert(GuardVar->getLinkage() == GV->getLinkage() &&
2688 "static local from the same function had different linkage");
2689
2690 if (!HasPerVariableGuard) {
2691 // Pseudo code for the test:
2692 // if (!(GuardVar & MyGuardBit)) {
2693 // GuardVar |= MyGuardBit;
2694 // ... initialize the object ...;
2695 // }
2696
2697 // Test our bit from the guard variable.
2698 llvm::ConstantInt *Bit = llvm::ConstantInt::get(GuardTy, 1ULL << GuardNum);
2699 llvm::LoadInst *LI = Builder.CreateLoad(GuardAddr);
2700 llvm::Value *NeedsInit =
2701 Builder.CreateICmpEQ(Builder.CreateAnd(LI, Bit), Zero);
2702 llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init");
2703 llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end");
2704 CGF.EmitCXXGuardedInitBranch(NeedsInit, InitBlock, EndBlock,
2705 CodeGenFunction::GuardKind::VariableGuard, &D);
2706
2707 // Set our bit in the guard variable and emit the initializer and add a global
2708 // destructor if appropriate.
2709 CGF.EmitBlock(InitBlock);
2710 Builder.CreateStore(Builder.CreateOr(LI, Bit), GuardAddr);
2711 CGF.EHStack.pushCleanup<ResetGuardBit>(EHCleanup, GuardAddr, GuardNum);
2712 CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit);
2713 CGF.PopCleanupBlock();
2714 Builder.CreateBr(EndBlock);
2715
2716 // Continue.
2717 CGF.EmitBlock(EndBlock);
2718 } else {
2719 // Pseudo code for the test:
2720 // if (TSS > _Init_thread_epoch) {
2721 // _Init_thread_header(&TSS);
2722 // if (TSS == -1) {
2723 // ... initialize the object ...;
2724 // _Init_thread_footer(&TSS);
2725 // }
2726 // }
2727 //
2728 // The algorithm is almost identical to what can be found in the appendix
2729 // found in N2325.
2730
2731 // This BasicBLock determines whether or not we have any work to do.
2732 llvm::LoadInst *FirstGuardLoad = Builder.CreateLoad(GuardAddr);
2733 FirstGuardLoad->setOrdering(llvm::AtomicOrdering::Unordered);
2734 llvm::LoadInst *InitThreadEpoch =
2735 Builder.CreateLoad(getInitThreadEpochPtr(CGM));
2736 llvm::Value *IsUninitialized =
2737 Builder.CreateICmpSGT(FirstGuardLoad, InitThreadEpoch);
2738 llvm::BasicBlock *AttemptInitBlock = CGF.createBasicBlock("init.attempt");
2739 llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end");
2740 CGF.EmitCXXGuardedInitBranch(IsUninitialized, AttemptInitBlock, EndBlock,
2741 CodeGenFunction::GuardKind::VariableGuard, &D);
2742
2743 // This BasicBlock attempts to determine whether or not this thread is
2744 // responsible for doing the initialization.
2745 CGF.EmitBlock(AttemptInitBlock);
2746 CGF.EmitNounwindRuntimeCall(getInitThreadHeaderFn(CGM),
2747 GuardAddr.getPointer());
2748 llvm::LoadInst *SecondGuardLoad = Builder.CreateLoad(GuardAddr);
2749 SecondGuardLoad->setOrdering(llvm::AtomicOrdering::Unordered);
2750 llvm::Value *ShouldDoInit =
2751 Builder.CreateICmpEQ(SecondGuardLoad, getAllOnesInt());
2752 llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init");
2753 Builder.CreateCondBr(ShouldDoInit, InitBlock, EndBlock);
2754
2755 // Ok, we ended up getting selected as the initializing thread.
2756 CGF.EmitBlock(InitBlock);
2757 CGF.EHStack.pushCleanup<CallInitThreadAbort>(EHCleanup, GuardAddr);
2758 CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit);
2759 CGF.PopCleanupBlock();
2760 CGF.EmitNounwindRuntimeCall(getInitThreadFooterFn(CGM),
2761 GuardAddr.getPointer());
2762 Builder.CreateBr(EndBlock);
2763
2764 CGF.EmitBlock(EndBlock);
2765 }
2766 }
2767
isZeroInitializable(const MemberPointerType * MPT)2768 bool MicrosoftCXXABI::isZeroInitializable(const MemberPointerType *MPT) {
2769 // Null-ness for function memptrs only depends on the first field, which is
2770 // the function pointer. The rest don't matter, so we can zero initialize.
2771 if (MPT->isMemberFunctionPointer())
2772 return true;
2773
2774 // The virtual base adjustment field is always -1 for null, so if we have one
2775 // we can't zero initialize. The field offset is sometimes also -1 if 0 is a
2776 // valid field offset.
2777 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
2778 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2779 return (!inheritanceModelHasVBTableOffsetField(Inheritance) &&
2780 RD->nullFieldOffsetIsZero());
2781 }
2782
2783 llvm::Type *
ConvertMemberPointerType(const MemberPointerType * MPT)2784 MicrosoftCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) {
2785 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
2786 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2787 llvm::SmallVector<llvm::Type *, 4> fields;
2788 if (MPT->isMemberFunctionPointer())
2789 fields.push_back(CGM.VoidPtrTy); // FunctionPointerOrVirtualThunk
2790 else
2791 fields.push_back(CGM.IntTy); // FieldOffset
2792
2793 if (inheritanceModelHasNVOffsetField(MPT->isMemberFunctionPointer(),
2794 Inheritance))
2795 fields.push_back(CGM.IntTy);
2796 if (inheritanceModelHasVBPtrOffsetField(Inheritance))
2797 fields.push_back(CGM.IntTy);
2798 if (inheritanceModelHasVBTableOffsetField(Inheritance))
2799 fields.push_back(CGM.IntTy); // VirtualBaseAdjustmentOffset
2800
2801 if (fields.size() == 1)
2802 return fields[0];
2803 return llvm::StructType::get(CGM.getLLVMContext(), fields);
2804 }
2805
2806 void MicrosoftCXXABI::
GetNullMemberPointerFields(const MemberPointerType * MPT,llvm::SmallVectorImpl<llvm::Constant * > & fields)2807 GetNullMemberPointerFields(const MemberPointerType *MPT,
2808 llvm::SmallVectorImpl<llvm::Constant *> &fields) {
2809 assert(fields.empty());
2810 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
2811 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2812 if (MPT->isMemberFunctionPointer()) {
2813 // FunctionPointerOrVirtualThunk
2814 fields.push_back(llvm::Constant::getNullValue(CGM.VoidPtrTy));
2815 } else {
2816 if (RD->nullFieldOffsetIsZero())
2817 fields.push_back(getZeroInt()); // FieldOffset
2818 else
2819 fields.push_back(getAllOnesInt()); // FieldOffset
2820 }
2821
2822 if (inheritanceModelHasNVOffsetField(MPT->isMemberFunctionPointer(),
2823 Inheritance))
2824 fields.push_back(getZeroInt());
2825 if (inheritanceModelHasVBPtrOffsetField(Inheritance))
2826 fields.push_back(getZeroInt());
2827 if (inheritanceModelHasVBTableOffsetField(Inheritance))
2828 fields.push_back(getAllOnesInt());
2829 }
2830
2831 llvm::Constant *
EmitNullMemberPointer(const MemberPointerType * MPT)2832 MicrosoftCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) {
2833 llvm::SmallVector<llvm::Constant *, 4> fields;
2834 GetNullMemberPointerFields(MPT, fields);
2835 if (fields.size() == 1)
2836 return fields[0];
2837 llvm::Constant *Res = llvm::ConstantStruct::getAnon(fields);
2838 assert(Res->getType() == ConvertMemberPointerType(MPT));
2839 return Res;
2840 }
2841
2842 llvm::Constant *
EmitFullMemberPointer(llvm::Constant * FirstField,bool IsMemberFunction,const CXXRecordDecl * RD,CharUnits NonVirtualBaseAdjustment,unsigned VBTableIndex)2843 MicrosoftCXXABI::EmitFullMemberPointer(llvm::Constant *FirstField,
2844 bool IsMemberFunction,
2845 const CXXRecordDecl *RD,
2846 CharUnits NonVirtualBaseAdjustment,
2847 unsigned VBTableIndex) {
2848 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2849
2850 // Single inheritance class member pointer are represented as scalars instead
2851 // of aggregates.
2852 if (inheritanceModelHasOnlyOneField(IsMemberFunction, Inheritance))
2853 return FirstField;
2854
2855 llvm::SmallVector<llvm::Constant *, 4> fields;
2856 fields.push_back(FirstField);
2857
2858 if (inheritanceModelHasNVOffsetField(IsMemberFunction, Inheritance))
2859 fields.push_back(llvm::ConstantInt::get(
2860 CGM.IntTy, NonVirtualBaseAdjustment.getQuantity()));
2861
2862 if (inheritanceModelHasVBPtrOffsetField(Inheritance)) {
2863 CharUnits Offs = CharUnits::Zero();
2864 if (VBTableIndex)
2865 Offs = getContext().getASTRecordLayout(RD).getVBPtrOffset();
2866 fields.push_back(llvm::ConstantInt::get(CGM.IntTy, Offs.getQuantity()));
2867 }
2868
2869 // The rest of the fields are adjusted by conversions to a more derived class.
2870 if (inheritanceModelHasVBTableOffsetField(Inheritance))
2871 fields.push_back(llvm::ConstantInt::get(CGM.IntTy, VBTableIndex));
2872
2873 return llvm::ConstantStruct::getAnon(fields);
2874 }
2875
2876 llvm::Constant *
EmitMemberDataPointer(const MemberPointerType * MPT,CharUnits offset)2877 MicrosoftCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT,
2878 CharUnits offset) {
2879 return EmitMemberDataPointer(MPT->getMostRecentCXXRecordDecl(), offset);
2880 }
2881
EmitMemberDataPointer(const CXXRecordDecl * RD,CharUnits offset)2882 llvm::Constant *MicrosoftCXXABI::EmitMemberDataPointer(const CXXRecordDecl *RD,
2883 CharUnits offset) {
2884 if (RD->getMSInheritanceModel() ==
2885 MSInheritanceModel::Virtual)
2886 offset -= getContext().getOffsetOfBaseWithVBPtr(RD);
2887 llvm::Constant *FirstField =
2888 llvm::ConstantInt::get(CGM.IntTy, offset.getQuantity());
2889 return EmitFullMemberPointer(FirstField, /*IsMemberFunction=*/false, RD,
2890 CharUnits::Zero(), /*VBTableIndex=*/0);
2891 }
2892
EmitMemberPointer(const APValue & MP,QualType MPType)2893 llvm::Constant *MicrosoftCXXABI::EmitMemberPointer(const APValue &MP,
2894 QualType MPType) {
2895 const MemberPointerType *DstTy = MPType->castAs<MemberPointerType>();
2896 const ValueDecl *MPD = MP.getMemberPointerDecl();
2897 if (!MPD)
2898 return EmitNullMemberPointer(DstTy);
2899
2900 ASTContext &Ctx = getContext();
2901 ArrayRef<const CXXRecordDecl *> MemberPointerPath = MP.getMemberPointerPath();
2902
2903 llvm::Constant *C;
2904 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MPD)) {
2905 C = EmitMemberFunctionPointer(MD);
2906 } else {
2907 // For a pointer to data member, start off with the offset of the field in
2908 // the class in which it was declared, and convert from there if necessary.
2909 // For indirect field decls, get the outermost anonymous field and use the
2910 // parent class.
2911 CharUnits FieldOffset = Ctx.toCharUnitsFromBits(Ctx.getFieldOffset(MPD));
2912 const FieldDecl *FD = dyn_cast<FieldDecl>(MPD);
2913 if (!FD)
2914 FD = cast<FieldDecl>(*cast<IndirectFieldDecl>(MPD)->chain_begin());
2915 const CXXRecordDecl *RD = cast<CXXRecordDecl>(FD->getParent());
2916 RD = RD->getMostRecentNonInjectedDecl();
2917 C = EmitMemberDataPointer(RD, FieldOffset);
2918 }
2919
2920 if (!MemberPointerPath.empty()) {
2921 const CXXRecordDecl *SrcRD = cast<CXXRecordDecl>(MPD->getDeclContext());
2922 const Type *SrcRecTy = Ctx.getTypeDeclType(SrcRD).getTypePtr();
2923 const MemberPointerType *SrcTy =
2924 Ctx.getMemberPointerType(DstTy->getPointeeType(), SrcRecTy)
2925 ->castAs<MemberPointerType>();
2926
2927 bool DerivedMember = MP.isMemberPointerToDerivedMember();
2928 SmallVector<const CXXBaseSpecifier *, 4> DerivedToBasePath;
2929 const CXXRecordDecl *PrevRD = SrcRD;
2930 for (const CXXRecordDecl *PathElem : MemberPointerPath) {
2931 const CXXRecordDecl *Base = nullptr;
2932 const CXXRecordDecl *Derived = nullptr;
2933 if (DerivedMember) {
2934 Base = PathElem;
2935 Derived = PrevRD;
2936 } else {
2937 Base = PrevRD;
2938 Derived = PathElem;
2939 }
2940 for (const CXXBaseSpecifier &BS : Derived->bases())
2941 if (BS.getType()->getAsCXXRecordDecl()->getCanonicalDecl() ==
2942 Base->getCanonicalDecl())
2943 DerivedToBasePath.push_back(&BS);
2944 PrevRD = PathElem;
2945 }
2946 assert(DerivedToBasePath.size() == MemberPointerPath.size());
2947
2948 CastKind CK = DerivedMember ? CK_DerivedToBaseMemberPointer
2949 : CK_BaseToDerivedMemberPointer;
2950 C = EmitMemberPointerConversion(SrcTy, DstTy, CK, DerivedToBasePath.begin(),
2951 DerivedToBasePath.end(), C);
2952 }
2953 return C;
2954 }
2955
2956 llvm::Constant *
EmitMemberFunctionPointer(const CXXMethodDecl * MD)2957 MicrosoftCXXABI::EmitMemberFunctionPointer(const CXXMethodDecl *MD) {
2958 assert(MD->isInstance() && "Member function must not be static!");
2959
2960 CharUnits NonVirtualBaseAdjustment = CharUnits::Zero();
2961 const CXXRecordDecl *RD = MD->getParent()->getMostRecentNonInjectedDecl();
2962 CodeGenTypes &Types = CGM.getTypes();
2963
2964 unsigned VBTableIndex = 0;
2965 llvm::Constant *FirstField;
2966 const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>();
2967 if (!MD->isVirtual()) {
2968 llvm::Type *Ty;
2969 // Check whether the function has a computable LLVM signature.
2970 if (Types.isFuncTypeConvertible(FPT)) {
2971 // The function has a computable LLVM signature; use the correct type.
2972 Ty = Types.GetFunctionType(Types.arrangeCXXMethodDeclaration(MD));
2973 } else {
2974 // Use an arbitrary non-function type to tell GetAddrOfFunction that the
2975 // function type is incomplete.
2976 Ty = CGM.PtrDiffTy;
2977 }
2978 FirstField = CGM.GetAddrOfFunction(MD, Ty);
2979 } else {
2980 auto &VTableContext = CGM.getMicrosoftVTableContext();
2981 MethodVFTableLocation ML = VTableContext.getMethodVFTableLocation(MD);
2982 FirstField = EmitVirtualMemPtrThunk(MD, ML);
2983 // Include the vfptr adjustment if the method is in a non-primary vftable.
2984 NonVirtualBaseAdjustment += ML.VFPtrOffset;
2985 if (ML.VBase)
2986 VBTableIndex = VTableContext.getVBTableIndex(RD, ML.VBase) * 4;
2987 }
2988
2989 if (VBTableIndex == 0 &&
2990 RD->getMSInheritanceModel() ==
2991 MSInheritanceModel::Virtual)
2992 NonVirtualBaseAdjustment -= getContext().getOffsetOfBaseWithVBPtr(RD);
2993
2994 // The rest of the fields are common with data member pointers.
2995 return EmitFullMemberPointer(FirstField, /*IsMemberFunction=*/true, RD,
2996 NonVirtualBaseAdjustment, VBTableIndex);
2997 }
2998
2999 /// Member pointers are the same if they're either bitwise identical *or* both
3000 /// null. Null-ness for function members is determined by the first field,
3001 /// while for data member pointers we must compare all fields.
3002 llvm::Value *
EmitMemberPointerComparison(CodeGenFunction & CGF,llvm::Value * L,llvm::Value * R,const MemberPointerType * MPT,bool Inequality)3003 MicrosoftCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF,
3004 llvm::Value *L,
3005 llvm::Value *R,
3006 const MemberPointerType *MPT,
3007 bool Inequality) {
3008 CGBuilderTy &Builder = CGF.Builder;
3009
3010 // Handle != comparisons by switching the sense of all boolean operations.
3011 llvm::ICmpInst::Predicate Eq;
3012 llvm::Instruction::BinaryOps And, Or;
3013 if (Inequality) {
3014 Eq = llvm::ICmpInst::ICMP_NE;
3015 And = llvm::Instruction::Or;
3016 Or = llvm::Instruction::And;
3017 } else {
3018 Eq = llvm::ICmpInst::ICMP_EQ;
3019 And = llvm::Instruction::And;
3020 Or = llvm::Instruction::Or;
3021 }
3022
3023 // If this is a single field member pointer (single inheritance), this is a
3024 // single icmp.
3025 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
3026 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
3027 if (inheritanceModelHasOnlyOneField(MPT->isMemberFunctionPointer(),
3028 Inheritance))
3029 return Builder.CreateICmp(Eq, L, R);
3030
3031 // Compare the first field.
3032 llvm::Value *L0 = Builder.CreateExtractValue(L, 0, "lhs.0");
3033 llvm::Value *R0 = Builder.CreateExtractValue(R, 0, "rhs.0");
3034 llvm::Value *Cmp0 = Builder.CreateICmp(Eq, L0, R0, "memptr.cmp.first");
3035
3036 // Compare everything other than the first field.
3037 llvm::Value *Res = nullptr;
3038 llvm::StructType *LType = cast<llvm::StructType>(L->getType());
3039 for (unsigned I = 1, E = LType->getNumElements(); I != E; ++I) {
3040 llvm::Value *LF = Builder.CreateExtractValue(L, I);
3041 llvm::Value *RF = Builder.CreateExtractValue(R, I);
3042 llvm::Value *Cmp = Builder.CreateICmp(Eq, LF, RF, "memptr.cmp.rest");
3043 if (Res)
3044 Res = Builder.CreateBinOp(And, Res, Cmp);
3045 else
3046 Res = Cmp;
3047 }
3048
3049 // Check if the first field is 0 if this is a function pointer.
3050 if (MPT->isMemberFunctionPointer()) {
3051 // (l1 == r1 && ...) || l0 == 0
3052 llvm::Value *Zero = llvm::Constant::getNullValue(L0->getType());
3053 llvm::Value *IsZero = Builder.CreateICmp(Eq, L0, Zero, "memptr.cmp.iszero");
3054 Res = Builder.CreateBinOp(Or, Res, IsZero);
3055 }
3056
3057 // Combine the comparison of the first field, which must always be true for
3058 // this comparison to succeeed.
3059 return Builder.CreateBinOp(And, Res, Cmp0, "memptr.cmp");
3060 }
3061
3062 llvm::Value *
EmitMemberPointerIsNotNull(CodeGenFunction & CGF,llvm::Value * MemPtr,const MemberPointerType * MPT)3063 MicrosoftCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
3064 llvm::Value *MemPtr,
3065 const MemberPointerType *MPT) {
3066 CGBuilderTy &Builder = CGF.Builder;
3067 llvm::SmallVector<llvm::Constant *, 4> fields;
3068 // We only need one field for member functions.
3069 if (MPT->isMemberFunctionPointer())
3070 fields.push_back(llvm::Constant::getNullValue(CGM.VoidPtrTy));
3071 else
3072 GetNullMemberPointerFields(MPT, fields);
3073 assert(!fields.empty());
3074 llvm::Value *FirstField = MemPtr;
3075 if (MemPtr->getType()->isStructTy())
3076 FirstField = Builder.CreateExtractValue(MemPtr, 0);
3077 llvm::Value *Res = Builder.CreateICmpNE(FirstField, fields[0], "memptr.cmp0");
3078
3079 // For function member pointers, we only need to test the function pointer
3080 // field. The other fields if any can be garbage.
3081 if (MPT->isMemberFunctionPointer())
3082 return Res;
3083
3084 // Otherwise, emit a series of compares and combine the results.
3085 for (int I = 1, E = fields.size(); I < E; ++I) {
3086 llvm::Value *Field = Builder.CreateExtractValue(MemPtr, I);
3087 llvm::Value *Next = Builder.CreateICmpNE(Field, fields[I], "memptr.cmp");
3088 Res = Builder.CreateOr(Res, Next, "memptr.tobool");
3089 }
3090 return Res;
3091 }
3092
MemberPointerConstantIsNull(const MemberPointerType * MPT,llvm::Constant * Val)3093 bool MicrosoftCXXABI::MemberPointerConstantIsNull(const MemberPointerType *MPT,
3094 llvm::Constant *Val) {
3095 // Function pointers are null if the pointer in the first field is null.
3096 if (MPT->isMemberFunctionPointer()) {
3097 llvm::Constant *FirstField = Val->getType()->isStructTy() ?
3098 Val->getAggregateElement(0U) : Val;
3099 return FirstField->isNullValue();
3100 }
3101
3102 // If it's not a function pointer and it's zero initializable, we can easily
3103 // check zero.
3104 if (isZeroInitializable(MPT) && Val->isNullValue())
3105 return true;
3106
3107 // Otherwise, break down all the fields for comparison. Hopefully these
3108 // little Constants are reused, while a big null struct might not be.
3109 llvm::SmallVector<llvm::Constant *, 4> Fields;
3110 GetNullMemberPointerFields(MPT, Fields);
3111 if (Fields.size() == 1) {
3112 assert(Val->getType()->isIntegerTy());
3113 return Val == Fields[0];
3114 }
3115
3116 unsigned I, E;
3117 for (I = 0, E = Fields.size(); I != E; ++I) {
3118 if (Val->getAggregateElement(I) != Fields[I])
3119 break;
3120 }
3121 return I == E;
3122 }
3123
3124 llvm::Value *
GetVBaseOffsetFromVBPtr(CodeGenFunction & CGF,Address This,llvm::Value * VBPtrOffset,llvm::Value * VBTableOffset,llvm::Value ** VBPtrOut)3125 MicrosoftCXXABI::GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,
3126 Address This,
3127 llvm::Value *VBPtrOffset,
3128 llvm::Value *VBTableOffset,
3129 llvm::Value **VBPtrOut) {
3130 CGBuilderTy &Builder = CGF.Builder;
3131 // Load the vbtable pointer from the vbptr in the instance.
3132 llvm::Value *VBPtr = Builder.CreateInBoundsGEP(CGM.Int8Ty, This.getPointer(),
3133 VBPtrOffset, "vbptr");
3134 if (VBPtrOut)
3135 *VBPtrOut = VBPtr;
3136
3137 CharUnits VBPtrAlign;
3138 if (auto CI = dyn_cast<llvm::ConstantInt>(VBPtrOffset)) {
3139 VBPtrAlign = This.getAlignment().alignmentAtOffset(
3140 CharUnits::fromQuantity(CI->getSExtValue()));
3141 } else {
3142 VBPtrAlign = CGF.getPointerAlign();
3143 }
3144
3145 llvm::Value *VBTable = Builder.CreateAlignedLoad(
3146 CGM.Int32Ty->getPointerTo(0), VBPtr, VBPtrAlign, "vbtable");
3147
3148 // Translate from byte offset to table index. It improves analyzability.
3149 llvm::Value *VBTableIndex = Builder.CreateAShr(
3150 VBTableOffset, llvm::ConstantInt::get(VBTableOffset->getType(), 2),
3151 "vbtindex", /*isExact=*/true);
3152
3153 // Load an i32 offset from the vb-table.
3154 llvm::Value *VBaseOffs =
3155 Builder.CreateInBoundsGEP(CGM.Int32Ty, VBTable, VBTableIndex);
3156 return Builder.CreateAlignedLoad(CGM.Int32Ty, VBaseOffs,
3157 CharUnits::fromQuantity(4), "vbase_offs");
3158 }
3159
3160 // Returns an adjusted base cast to i8*, since we do more address arithmetic on
3161 // it.
AdjustVirtualBase(CodeGenFunction & CGF,const Expr * E,const CXXRecordDecl * RD,Address Base,llvm::Value * VBTableOffset,llvm::Value * VBPtrOffset)3162 llvm::Value *MicrosoftCXXABI::AdjustVirtualBase(
3163 CodeGenFunction &CGF, const Expr *E, const CXXRecordDecl *RD,
3164 Address Base, llvm::Value *VBTableOffset, llvm::Value *VBPtrOffset) {
3165 CGBuilderTy &Builder = CGF.Builder;
3166 Base = Base.withElementType(CGM.Int8Ty);
3167 llvm::BasicBlock *OriginalBB = nullptr;
3168 llvm::BasicBlock *SkipAdjustBB = nullptr;
3169 llvm::BasicBlock *VBaseAdjustBB = nullptr;
3170
3171 // In the unspecified inheritance model, there might not be a vbtable at all,
3172 // in which case we need to skip the virtual base lookup. If there is a
3173 // vbtable, the first entry is a no-op entry that gives back the original
3174 // base, so look for a virtual base adjustment offset of zero.
3175 if (VBPtrOffset) {
3176 OriginalBB = Builder.GetInsertBlock();
3177 VBaseAdjustBB = CGF.createBasicBlock("memptr.vadjust");
3178 SkipAdjustBB = CGF.createBasicBlock("memptr.skip_vadjust");
3179 llvm::Value *IsVirtual =
3180 Builder.CreateICmpNE(VBTableOffset, getZeroInt(),
3181 "memptr.is_vbase");
3182 Builder.CreateCondBr(IsVirtual, VBaseAdjustBB, SkipAdjustBB);
3183 CGF.EmitBlock(VBaseAdjustBB);
3184 }
3185
3186 // If we weren't given a dynamic vbptr offset, RD should be complete and we'll
3187 // know the vbptr offset.
3188 if (!VBPtrOffset) {
3189 CharUnits offs = CharUnits::Zero();
3190 if (!RD->hasDefinition()) {
3191 DiagnosticsEngine &Diags = CGF.CGM.getDiags();
3192 unsigned DiagID = Diags.getCustomDiagID(
3193 DiagnosticsEngine::Error,
3194 "member pointer representation requires a "
3195 "complete class type for %0 to perform this expression");
3196 Diags.Report(E->getExprLoc(), DiagID) << RD << E->getSourceRange();
3197 } else if (RD->getNumVBases())
3198 offs = getContext().getASTRecordLayout(RD).getVBPtrOffset();
3199 VBPtrOffset = llvm::ConstantInt::get(CGM.IntTy, offs.getQuantity());
3200 }
3201 llvm::Value *VBPtr = nullptr;
3202 llvm::Value *VBaseOffs =
3203 GetVBaseOffsetFromVBPtr(CGF, Base, VBPtrOffset, VBTableOffset, &VBPtr);
3204 llvm::Value *AdjustedBase =
3205 Builder.CreateInBoundsGEP(CGM.Int8Ty, VBPtr, VBaseOffs);
3206
3207 // Merge control flow with the case where we didn't have to adjust.
3208 if (VBaseAdjustBB) {
3209 Builder.CreateBr(SkipAdjustBB);
3210 CGF.EmitBlock(SkipAdjustBB);
3211 llvm::PHINode *Phi = Builder.CreatePHI(CGM.Int8PtrTy, 2, "memptr.base");
3212 Phi->addIncoming(Base.getPointer(), OriginalBB);
3213 Phi->addIncoming(AdjustedBase, VBaseAdjustBB);
3214 return Phi;
3215 }
3216 return AdjustedBase;
3217 }
3218
EmitMemberDataPointerAddress(CodeGenFunction & CGF,const Expr * E,Address Base,llvm::Value * MemPtr,const MemberPointerType * MPT)3219 llvm::Value *MicrosoftCXXABI::EmitMemberDataPointerAddress(
3220 CodeGenFunction &CGF, const Expr *E, Address Base, llvm::Value *MemPtr,
3221 const MemberPointerType *MPT) {
3222 assert(MPT->isMemberDataPointer());
3223 CGBuilderTy &Builder = CGF.Builder;
3224 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
3225 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
3226
3227 // Extract the fields we need, regardless of model. We'll apply them if we
3228 // have them.
3229 llvm::Value *FieldOffset = MemPtr;
3230 llvm::Value *VirtualBaseAdjustmentOffset = nullptr;
3231 llvm::Value *VBPtrOffset = nullptr;
3232 if (MemPtr->getType()->isStructTy()) {
3233 // We need to extract values.
3234 unsigned I = 0;
3235 FieldOffset = Builder.CreateExtractValue(MemPtr, I++);
3236 if (inheritanceModelHasVBPtrOffsetField(Inheritance))
3237 VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++);
3238 if (inheritanceModelHasVBTableOffsetField(Inheritance))
3239 VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++);
3240 }
3241
3242 llvm::Value *Addr;
3243 if (VirtualBaseAdjustmentOffset) {
3244 Addr = AdjustVirtualBase(CGF, E, RD, Base, VirtualBaseAdjustmentOffset,
3245 VBPtrOffset);
3246 } else {
3247 Addr = Base.getPointer();
3248 }
3249
3250 // Apply the offset, which we assume is non-null.
3251 return Builder.CreateInBoundsGEP(CGF.Int8Ty, Addr, FieldOffset,
3252 "memptr.offset");
3253 }
3254
3255 llvm::Value *
EmitMemberPointerConversion(CodeGenFunction & CGF,const CastExpr * E,llvm::Value * Src)3256 MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
3257 const CastExpr *E,
3258 llvm::Value *Src) {
3259 assert(E->getCastKind() == CK_DerivedToBaseMemberPointer ||
3260 E->getCastKind() == CK_BaseToDerivedMemberPointer ||
3261 E->getCastKind() == CK_ReinterpretMemberPointer);
3262
3263 // Use constant emission if we can.
3264 if (isa<llvm::Constant>(Src))
3265 return EmitMemberPointerConversion(E, cast<llvm::Constant>(Src));
3266
3267 // We may be adding or dropping fields from the member pointer, so we need
3268 // both types and the inheritance models of both records.
3269 const MemberPointerType *SrcTy =
3270 E->getSubExpr()->getType()->castAs<MemberPointerType>();
3271 const MemberPointerType *DstTy = E->getType()->castAs<MemberPointerType>();
3272 bool IsFunc = SrcTy->isMemberFunctionPointer();
3273
3274 // If the classes use the same null representation, reinterpret_cast is a nop.
3275 bool IsReinterpret = E->getCastKind() == CK_ReinterpretMemberPointer;
3276 if (IsReinterpret && IsFunc)
3277 return Src;
3278
3279 CXXRecordDecl *SrcRD = SrcTy->getMostRecentCXXRecordDecl();
3280 CXXRecordDecl *DstRD = DstTy->getMostRecentCXXRecordDecl();
3281 if (IsReinterpret &&
3282 SrcRD->nullFieldOffsetIsZero() == DstRD->nullFieldOffsetIsZero())
3283 return Src;
3284
3285 CGBuilderTy &Builder = CGF.Builder;
3286
3287 // Branch past the conversion if Src is null.
3288 llvm::Value *IsNotNull = EmitMemberPointerIsNotNull(CGF, Src, SrcTy);
3289 llvm::Constant *DstNull = EmitNullMemberPointer(DstTy);
3290
3291 // C++ 5.2.10p9: The null member pointer value is converted to the null member
3292 // pointer value of the destination type.
3293 if (IsReinterpret) {
3294 // For reinterpret casts, sema ensures that src and dst are both functions
3295 // or data and have the same size, which means the LLVM types should match.
3296 assert(Src->getType() == DstNull->getType());
3297 return Builder.CreateSelect(IsNotNull, Src, DstNull);
3298 }
3299
3300 llvm::BasicBlock *OriginalBB = Builder.GetInsertBlock();
3301 llvm::BasicBlock *ConvertBB = CGF.createBasicBlock("memptr.convert");
3302 llvm::BasicBlock *ContinueBB = CGF.createBasicBlock("memptr.converted");
3303 Builder.CreateCondBr(IsNotNull, ConvertBB, ContinueBB);
3304 CGF.EmitBlock(ConvertBB);
3305
3306 llvm::Value *Dst = EmitNonNullMemberPointerConversion(
3307 SrcTy, DstTy, E->getCastKind(), E->path_begin(), E->path_end(), Src,
3308 Builder);
3309
3310 Builder.CreateBr(ContinueBB);
3311
3312 // In the continuation, choose between DstNull and Dst.
3313 CGF.EmitBlock(ContinueBB);
3314 llvm::PHINode *Phi = Builder.CreatePHI(DstNull->getType(), 2, "memptr.converted");
3315 Phi->addIncoming(DstNull, OriginalBB);
3316 Phi->addIncoming(Dst, ConvertBB);
3317 return Phi;
3318 }
3319
EmitNonNullMemberPointerConversion(const MemberPointerType * SrcTy,const MemberPointerType * DstTy,CastKind CK,CastExpr::path_const_iterator PathBegin,CastExpr::path_const_iterator PathEnd,llvm::Value * Src,CGBuilderTy & Builder)3320 llvm::Value *MicrosoftCXXABI::EmitNonNullMemberPointerConversion(
3321 const MemberPointerType *SrcTy, const MemberPointerType *DstTy, CastKind CK,
3322 CastExpr::path_const_iterator PathBegin,
3323 CastExpr::path_const_iterator PathEnd, llvm::Value *Src,
3324 CGBuilderTy &Builder) {
3325 const CXXRecordDecl *SrcRD = SrcTy->getMostRecentCXXRecordDecl();
3326 const CXXRecordDecl *DstRD = DstTy->getMostRecentCXXRecordDecl();
3327 MSInheritanceModel SrcInheritance = SrcRD->getMSInheritanceModel();
3328 MSInheritanceModel DstInheritance = DstRD->getMSInheritanceModel();
3329 bool IsFunc = SrcTy->isMemberFunctionPointer();
3330 bool IsConstant = isa<llvm::Constant>(Src);
3331
3332 // Decompose src.
3333 llvm::Value *FirstField = Src;
3334 llvm::Value *NonVirtualBaseAdjustment = getZeroInt();
3335 llvm::Value *VirtualBaseAdjustmentOffset = getZeroInt();
3336 llvm::Value *VBPtrOffset = getZeroInt();
3337 if (!inheritanceModelHasOnlyOneField(IsFunc, SrcInheritance)) {
3338 // We need to extract values.
3339 unsigned I = 0;
3340 FirstField = Builder.CreateExtractValue(Src, I++);
3341 if (inheritanceModelHasNVOffsetField(IsFunc, SrcInheritance))
3342 NonVirtualBaseAdjustment = Builder.CreateExtractValue(Src, I++);
3343 if (inheritanceModelHasVBPtrOffsetField(SrcInheritance))
3344 VBPtrOffset = Builder.CreateExtractValue(Src, I++);
3345 if (inheritanceModelHasVBTableOffsetField(SrcInheritance))
3346 VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(Src, I++);
3347 }
3348
3349 bool IsDerivedToBase = (CK == CK_DerivedToBaseMemberPointer);
3350 const MemberPointerType *DerivedTy = IsDerivedToBase ? SrcTy : DstTy;
3351 const CXXRecordDecl *DerivedClass = DerivedTy->getMostRecentCXXRecordDecl();
3352
3353 // For data pointers, we adjust the field offset directly. For functions, we
3354 // have a separate field.
3355 llvm::Value *&NVAdjustField = IsFunc ? NonVirtualBaseAdjustment : FirstField;
3356
3357 // The virtual inheritance model has a quirk: the virtual base table is always
3358 // referenced when dereferencing a member pointer even if the member pointer
3359 // is non-virtual. This is accounted for by adjusting the non-virtual offset
3360 // to point backwards to the top of the MDC from the first VBase. Undo this
3361 // adjustment to normalize the member pointer.
3362 llvm::Value *SrcVBIndexEqZero =
3363 Builder.CreateICmpEQ(VirtualBaseAdjustmentOffset, getZeroInt());
3364 if (SrcInheritance == MSInheritanceModel::Virtual) {
3365 if (int64_t SrcOffsetToFirstVBase =
3366 getContext().getOffsetOfBaseWithVBPtr(SrcRD).getQuantity()) {
3367 llvm::Value *UndoSrcAdjustment = Builder.CreateSelect(
3368 SrcVBIndexEqZero,
3369 llvm::ConstantInt::get(CGM.IntTy, SrcOffsetToFirstVBase),
3370 getZeroInt());
3371 NVAdjustField = Builder.CreateNSWAdd(NVAdjustField, UndoSrcAdjustment);
3372 }
3373 }
3374
3375 // A non-zero vbindex implies that we are dealing with a source member in a
3376 // floating virtual base in addition to some non-virtual offset. If the
3377 // vbindex is zero, we are dealing with a source that exists in a non-virtual,
3378 // fixed, base. The difference between these two cases is that the vbindex +
3379 // nvoffset *always* point to the member regardless of what context they are
3380 // evaluated in so long as the vbindex is adjusted. A member inside a fixed
3381 // base requires explicit nv adjustment.
3382 llvm::Constant *BaseClassOffset = llvm::ConstantInt::get(
3383 CGM.IntTy,
3384 CGM.computeNonVirtualBaseClassOffset(DerivedClass, PathBegin, PathEnd)
3385 .getQuantity());
3386
3387 llvm::Value *NVDisp;
3388 if (IsDerivedToBase)
3389 NVDisp = Builder.CreateNSWSub(NVAdjustField, BaseClassOffset, "adj");
3390 else
3391 NVDisp = Builder.CreateNSWAdd(NVAdjustField, BaseClassOffset, "adj");
3392
3393 NVAdjustField = Builder.CreateSelect(SrcVBIndexEqZero, NVDisp, getZeroInt());
3394
3395 // Update the vbindex to an appropriate value in the destination because
3396 // SrcRD's vbtable might not be a strict prefix of the one in DstRD.
3397 llvm::Value *DstVBIndexEqZero = SrcVBIndexEqZero;
3398 if (inheritanceModelHasVBTableOffsetField(DstInheritance) &&
3399 inheritanceModelHasVBTableOffsetField(SrcInheritance)) {
3400 if (llvm::GlobalVariable *VDispMap =
3401 getAddrOfVirtualDisplacementMap(SrcRD, DstRD)) {
3402 llvm::Value *VBIndex = Builder.CreateExactUDiv(
3403 VirtualBaseAdjustmentOffset, llvm::ConstantInt::get(CGM.IntTy, 4));
3404 if (IsConstant) {
3405 llvm::Constant *Mapping = VDispMap->getInitializer();
3406 VirtualBaseAdjustmentOffset =
3407 Mapping->getAggregateElement(cast<llvm::Constant>(VBIndex));
3408 } else {
3409 llvm::Value *Idxs[] = {getZeroInt(), VBIndex};
3410 VirtualBaseAdjustmentOffset = Builder.CreateAlignedLoad(
3411 CGM.IntTy, Builder.CreateInBoundsGEP(VDispMap->getValueType(),
3412 VDispMap, Idxs),
3413 CharUnits::fromQuantity(4));
3414 }
3415
3416 DstVBIndexEqZero =
3417 Builder.CreateICmpEQ(VirtualBaseAdjustmentOffset, getZeroInt());
3418 }
3419 }
3420
3421 // Set the VBPtrOffset to zero if the vbindex is zero. Otherwise, initialize
3422 // it to the offset of the vbptr.
3423 if (inheritanceModelHasVBPtrOffsetField(DstInheritance)) {
3424 llvm::Value *DstVBPtrOffset = llvm::ConstantInt::get(
3425 CGM.IntTy,
3426 getContext().getASTRecordLayout(DstRD).getVBPtrOffset().getQuantity());
3427 VBPtrOffset =
3428 Builder.CreateSelect(DstVBIndexEqZero, getZeroInt(), DstVBPtrOffset);
3429 }
3430
3431 // Likewise, apply a similar adjustment so that dereferencing the member
3432 // pointer correctly accounts for the distance between the start of the first
3433 // virtual base and the top of the MDC.
3434 if (DstInheritance == MSInheritanceModel::Virtual) {
3435 if (int64_t DstOffsetToFirstVBase =
3436 getContext().getOffsetOfBaseWithVBPtr(DstRD).getQuantity()) {
3437 llvm::Value *DoDstAdjustment = Builder.CreateSelect(
3438 DstVBIndexEqZero,
3439 llvm::ConstantInt::get(CGM.IntTy, DstOffsetToFirstVBase),
3440 getZeroInt());
3441 NVAdjustField = Builder.CreateNSWSub(NVAdjustField, DoDstAdjustment);
3442 }
3443 }
3444
3445 // Recompose dst from the null struct and the adjusted fields from src.
3446 llvm::Value *Dst;
3447 if (inheritanceModelHasOnlyOneField(IsFunc, DstInheritance)) {
3448 Dst = FirstField;
3449 } else {
3450 Dst = llvm::UndefValue::get(ConvertMemberPointerType(DstTy));
3451 unsigned Idx = 0;
3452 Dst = Builder.CreateInsertValue(Dst, FirstField, Idx++);
3453 if (inheritanceModelHasNVOffsetField(IsFunc, DstInheritance))
3454 Dst = Builder.CreateInsertValue(Dst, NonVirtualBaseAdjustment, Idx++);
3455 if (inheritanceModelHasVBPtrOffsetField(DstInheritance))
3456 Dst = Builder.CreateInsertValue(Dst, VBPtrOffset, Idx++);
3457 if (inheritanceModelHasVBTableOffsetField(DstInheritance))
3458 Dst = Builder.CreateInsertValue(Dst, VirtualBaseAdjustmentOffset, Idx++);
3459 }
3460 return Dst;
3461 }
3462
3463 llvm::Constant *
EmitMemberPointerConversion(const CastExpr * E,llvm::Constant * Src)3464 MicrosoftCXXABI::EmitMemberPointerConversion(const CastExpr *E,
3465 llvm::Constant *Src) {
3466 const MemberPointerType *SrcTy =
3467 E->getSubExpr()->getType()->castAs<MemberPointerType>();
3468 const MemberPointerType *DstTy = E->getType()->castAs<MemberPointerType>();
3469
3470 CastKind CK = E->getCastKind();
3471
3472 return EmitMemberPointerConversion(SrcTy, DstTy, CK, E->path_begin(),
3473 E->path_end(), Src);
3474 }
3475
EmitMemberPointerConversion(const MemberPointerType * SrcTy,const MemberPointerType * DstTy,CastKind CK,CastExpr::path_const_iterator PathBegin,CastExpr::path_const_iterator PathEnd,llvm::Constant * Src)3476 llvm::Constant *MicrosoftCXXABI::EmitMemberPointerConversion(
3477 const MemberPointerType *SrcTy, const MemberPointerType *DstTy, CastKind CK,
3478 CastExpr::path_const_iterator PathBegin,
3479 CastExpr::path_const_iterator PathEnd, llvm::Constant *Src) {
3480 assert(CK == CK_DerivedToBaseMemberPointer ||
3481 CK == CK_BaseToDerivedMemberPointer ||
3482 CK == CK_ReinterpretMemberPointer);
3483 // If src is null, emit a new null for dst. We can't return src because dst
3484 // might have a new representation.
3485 if (MemberPointerConstantIsNull(SrcTy, Src))
3486 return EmitNullMemberPointer(DstTy);
3487
3488 // We don't need to do anything for reinterpret_casts of non-null member
3489 // pointers. We should only get here when the two type representations have
3490 // the same size.
3491 if (CK == CK_ReinterpretMemberPointer)
3492 return Src;
3493
3494 CGBuilderTy Builder(CGM, CGM.getLLVMContext());
3495 auto *Dst = cast<llvm::Constant>(EmitNonNullMemberPointerConversion(
3496 SrcTy, DstTy, CK, PathBegin, PathEnd, Src, Builder));
3497
3498 return Dst;
3499 }
3500
EmitLoadOfMemberFunctionPointer(CodeGenFunction & CGF,const Expr * E,Address This,llvm::Value * & ThisPtrForCall,llvm::Value * MemPtr,const MemberPointerType * MPT)3501 CGCallee MicrosoftCXXABI::EmitLoadOfMemberFunctionPointer(
3502 CodeGenFunction &CGF, const Expr *E, Address This,
3503 llvm::Value *&ThisPtrForCall, llvm::Value *MemPtr,
3504 const MemberPointerType *MPT) {
3505 assert(MPT->isMemberFunctionPointer());
3506 const FunctionProtoType *FPT =
3507 MPT->getPointeeType()->castAs<FunctionProtoType>();
3508 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
3509 CGBuilderTy &Builder = CGF.Builder;
3510
3511 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
3512
3513 // Extract the fields we need, regardless of model. We'll apply them if we
3514 // have them.
3515 llvm::Value *FunctionPointer = MemPtr;
3516 llvm::Value *NonVirtualBaseAdjustment = nullptr;
3517 llvm::Value *VirtualBaseAdjustmentOffset = nullptr;
3518 llvm::Value *VBPtrOffset = nullptr;
3519 if (MemPtr->getType()->isStructTy()) {
3520 // We need to extract values.
3521 unsigned I = 0;
3522 FunctionPointer = Builder.CreateExtractValue(MemPtr, I++);
3523 if (inheritanceModelHasNVOffsetField(MPT, Inheritance))
3524 NonVirtualBaseAdjustment = Builder.CreateExtractValue(MemPtr, I++);
3525 if (inheritanceModelHasVBPtrOffsetField(Inheritance))
3526 VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++);
3527 if (inheritanceModelHasVBTableOffsetField(Inheritance))
3528 VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++);
3529 }
3530
3531 if (VirtualBaseAdjustmentOffset) {
3532 ThisPtrForCall = AdjustVirtualBase(CGF, E, RD, This,
3533 VirtualBaseAdjustmentOffset, VBPtrOffset);
3534 } else {
3535 ThisPtrForCall = This.getPointer();
3536 }
3537
3538 if (NonVirtualBaseAdjustment)
3539 ThisPtrForCall = Builder.CreateInBoundsGEP(CGF.Int8Ty, ThisPtrForCall,
3540 NonVirtualBaseAdjustment);
3541
3542 CGCallee Callee(FPT, FunctionPointer);
3543 return Callee;
3544 }
3545
CreateMicrosoftCXXABI(CodeGenModule & CGM)3546 CGCXXABI *clang::CodeGen::CreateMicrosoftCXXABI(CodeGenModule &CGM) {
3547 return new MicrosoftCXXABI(CGM);
3548 }
3549
3550 // MS RTTI Overview:
3551 // The run time type information emitted by cl.exe contains 5 distinct types of
3552 // structures. Many of them reference each other.
3553 //
3554 // TypeInfo: Static classes that are returned by typeid.
3555 //
3556 // CompleteObjectLocator: Referenced by vftables. They contain information
3557 // required for dynamic casting, including OffsetFromTop. They also contain
3558 // a reference to the TypeInfo for the type and a reference to the
3559 // CompleteHierarchyDescriptor for the type.
3560 //
3561 // ClassHierarchyDescriptor: Contains information about a class hierarchy.
3562 // Used during dynamic_cast to walk a class hierarchy. References a base
3563 // class array and the size of said array.
3564 //
3565 // BaseClassArray: Contains a list of classes in a hierarchy. BaseClassArray is
3566 // somewhat of a misnomer because the most derived class is also in the list
3567 // as well as multiple copies of virtual bases (if they occur multiple times
3568 // in the hierarchy.) The BaseClassArray contains one BaseClassDescriptor for
3569 // every path in the hierarchy, in pre-order depth first order. Note, we do
3570 // not declare a specific llvm type for BaseClassArray, it's merely an array
3571 // of BaseClassDescriptor pointers.
3572 //
3573 // BaseClassDescriptor: Contains information about a class in a class hierarchy.
3574 // BaseClassDescriptor is also somewhat of a misnomer for the same reason that
3575 // BaseClassArray is. It contains information about a class within a
3576 // hierarchy such as: is this base is ambiguous and what is its offset in the
3577 // vbtable. The names of the BaseClassDescriptors have all of their fields
3578 // mangled into them so they can be aggressively deduplicated by the linker.
3579
getTypeInfoVTable(CodeGenModule & CGM)3580 static llvm::GlobalVariable *getTypeInfoVTable(CodeGenModule &CGM) {
3581 StringRef MangledName("??_7type_info@@6B@");
3582 if (auto VTable = CGM.getModule().getNamedGlobal(MangledName))
3583 return VTable;
3584 return new llvm::GlobalVariable(CGM.getModule(), CGM.Int8PtrTy,
3585 /*isConstant=*/true,
3586 llvm::GlobalVariable::ExternalLinkage,
3587 /*Initializer=*/nullptr, MangledName);
3588 }
3589
3590 namespace {
3591
3592 /// A Helper struct that stores information about a class in a class
3593 /// hierarchy. The information stored in these structs struct is used during
3594 /// the generation of ClassHierarchyDescriptors and BaseClassDescriptors.
3595 // During RTTI creation, MSRTTIClasses are stored in a contiguous array with
3596 // implicit depth first pre-order tree connectivity. getFirstChild and
3597 // getNextSibling allow us to walk the tree efficiently.
3598 struct MSRTTIClass {
3599 enum {
3600 IsPrivateOnPath = 1 | 8,
3601 IsAmbiguous = 2,
3602 IsPrivate = 4,
3603 IsVirtual = 16,
3604 HasHierarchyDescriptor = 64
3605 };
MSRTTIClass__anond2fcd7db0811::MSRTTIClass3606 MSRTTIClass(const CXXRecordDecl *RD) : RD(RD) {}
3607 uint32_t initialize(const MSRTTIClass *Parent,
3608 const CXXBaseSpecifier *Specifier);
3609
getFirstChild__anond2fcd7db0811::MSRTTIClass3610 MSRTTIClass *getFirstChild() { return this + 1; }
getNextChild__anond2fcd7db0811::MSRTTIClass3611 static MSRTTIClass *getNextChild(MSRTTIClass *Child) {
3612 return Child + 1 + Child->NumBases;
3613 }
3614
3615 const CXXRecordDecl *RD, *VirtualRoot;
3616 uint32_t Flags, NumBases, OffsetInVBase;
3617 };
3618
3619 /// Recursively initialize the base class array.
initialize(const MSRTTIClass * Parent,const CXXBaseSpecifier * Specifier)3620 uint32_t MSRTTIClass::initialize(const MSRTTIClass *Parent,
3621 const CXXBaseSpecifier *Specifier) {
3622 Flags = HasHierarchyDescriptor;
3623 if (!Parent) {
3624 VirtualRoot = nullptr;
3625 OffsetInVBase = 0;
3626 } else {
3627 if (Specifier->getAccessSpecifier() != AS_public)
3628 Flags |= IsPrivate | IsPrivateOnPath;
3629 if (Specifier->isVirtual()) {
3630 Flags |= IsVirtual;
3631 VirtualRoot = RD;
3632 OffsetInVBase = 0;
3633 } else {
3634 if (Parent->Flags & IsPrivateOnPath)
3635 Flags |= IsPrivateOnPath;
3636 VirtualRoot = Parent->VirtualRoot;
3637 OffsetInVBase = Parent->OffsetInVBase + RD->getASTContext()
3638 .getASTRecordLayout(Parent->RD).getBaseClassOffset(RD).getQuantity();
3639 }
3640 }
3641 NumBases = 0;
3642 MSRTTIClass *Child = getFirstChild();
3643 for (const CXXBaseSpecifier &Base : RD->bases()) {
3644 NumBases += Child->initialize(this, &Base) + 1;
3645 Child = getNextChild(Child);
3646 }
3647 return NumBases;
3648 }
3649
getLinkageForRTTI(QualType Ty)3650 static llvm::GlobalValue::LinkageTypes getLinkageForRTTI(QualType Ty) {
3651 switch (Ty->getLinkage()) {
3652 case Linkage::Invalid:
3653 llvm_unreachable("Linkage hasn't been computed!");
3654
3655 case Linkage::None:
3656 case Linkage::Internal:
3657 case Linkage::UniqueExternal:
3658 return llvm::GlobalValue::InternalLinkage;
3659
3660 case Linkage::VisibleNone:
3661 case Linkage::Module:
3662 case Linkage::External:
3663 return llvm::GlobalValue::LinkOnceODRLinkage;
3664 }
3665 llvm_unreachable("Invalid linkage!");
3666 }
3667
3668 /// An ephemeral helper class for building MS RTTI types. It caches some
3669 /// calls to the module and information about the most derived class in a
3670 /// hierarchy.
3671 struct MSRTTIBuilder {
3672 enum {
3673 HasBranchingHierarchy = 1,
3674 HasVirtualBranchingHierarchy = 2,
3675 HasAmbiguousBases = 4
3676 };
3677
MSRTTIBuilder__anond2fcd7db0811::MSRTTIBuilder3678 MSRTTIBuilder(MicrosoftCXXABI &ABI, const CXXRecordDecl *RD)
3679 : CGM(ABI.CGM), Context(CGM.getContext()),
3680 VMContext(CGM.getLLVMContext()), Module(CGM.getModule()), RD(RD),
3681 Linkage(getLinkageForRTTI(CGM.getContext().getTagDeclType(RD))),
3682 ABI(ABI) {}
3683
3684 llvm::GlobalVariable *getBaseClassDescriptor(const MSRTTIClass &Classes);
3685 llvm::GlobalVariable *
3686 getBaseClassArray(SmallVectorImpl<MSRTTIClass> &Classes);
3687 llvm::GlobalVariable *getClassHierarchyDescriptor();
3688 llvm::GlobalVariable *getCompleteObjectLocator(const VPtrInfo &Info);
3689
3690 CodeGenModule &CGM;
3691 ASTContext &Context;
3692 llvm::LLVMContext &VMContext;
3693 llvm::Module &Module;
3694 const CXXRecordDecl *RD;
3695 llvm::GlobalVariable::LinkageTypes Linkage;
3696 MicrosoftCXXABI &ABI;
3697 };
3698
3699 } // namespace
3700
3701 /// Recursively serializes a class hierarchy in pre-order depth first
3702 /// order.
serializeClassHierarchy(SmallVectorImpl<MSRTTIClass> & Classes,const CXXRecordDecl * RD)3703 static void serializeClassHierarchy(SmallVectorImpl<MSRTTIClass> &Classes,
3704 const CXXRecordDecl *RD) {
3705 Classes.push_back(MSRTTIClass(RD));
3706 for (const CXXBaseSpecifier &Base : RD->bases())
3707 serializeClassHierarchy(Classes, Base.getType()->getAsCXXRecordDecl());
3708 }
3709
3710 /// Find ambiguity among base classes.
3711 static void
detectAmbiguousBases(SmallVectorImpl<MSRTTIClass> & Classes)3712 detectAmbiguousBases(SmallVectorImpl<MSRTTIClass> &Classes) {
3713 llvm::SmallPtrSet<const CXXRecordDecl *, 8> VirtualBases;
3714 llvm::SmallPtrSet<const CXXRecordDecl *, 8> UniqueBases;
3715 llvm::SmallPtrSet<const CXXRecordDecl *, 8> AmbiguousBases;
3716 for (MSRTTIClass *Class = &Classes.front(); Class <= &Classes.back();) {
3717 if ((Class->Flags & MSRTTIClass::IsVirtual) &&
3718 !VirtualBases.insert(Class->RD).second) {
3719 Class = MSRTTIClass::getNextChild(Class);
3720 continue;
3721 }
3722 if (!UniqueBases.insert(Class->RD).second)
3723 AmbiguousBases.insert(Class->RD);
3724 Class++;
3725 }
3726 if (AmbiguousBases.empty())
3727 return;
3728 for (MSRTTIClass &Class : Classes)
3729 if (AmbiguousBases.count(Class.RD))
3730 Class.Flags |= MSRTTIClass::IsAmbiguous;
3731 }
3732
getClassHierarchyDescriptor()3733 llvm::GlobalVariable *MSRTTIBuilder::getClassHierarchyDescriptor() {
3734 SmallString<256> MangledName;
3735 {
3736 llvm::raw_svector_ostream Out(MangledName);
3737 ABI.getMangleContext().mangleCXXRTTIClassHierarchyDescriptor(RD, Out);
3738 }
3739
3740 // Check to see if we've already declared this ClassHierarchyDescriptor.
3741 if (auto CHD = Module.getNamedGlobal(MangledName))
3742 return CHD;
3743
3744 // Serialize the class hierarchy and initialize the CHD Fields.
3745 SmallVector<MSRTTIClass, 8> Classes;
3746 serializeClassHierarchy(Classes, RD);
3747 Classes.front().initialize(/*Parent=*/nullptr, /*Specifier=*/nullptr);
3748 detectAmbiguousBases(Classes);
3749 int Flags = 0;
3750 for (const MSRTTIClass &Class : Classes) {
3751 if (Class.RD->getNumBases() > 1)
3752 Flags |= HasBranchingHierarchy;
3753 // Note: cl.exe does not calculate "HasAmbiguousBases" correctly. We
3754 // believe the field isn't actually used.
3755 if (Class.Flags & MSRTTIClass::IsAmbiguous)
3756 Flags |= HasAmbiguousBases;
3757 }
3758 if ((Flags & HasBranchingHierarchy) && RD->getNumVBases() != 0)
3759 Flags |= HasVirtualBranchingHierarchy;
3760 // These gep indices are used to get the address of the first element of the
3761 // base class array.
3762 llvm::Value *GEPIndices[] = {llvm::ConstantInt::get(CGM.IntTy, 0),
3763 llvm::ConstantInt::get(CGM.IntTy, 0)};
3764
3765 // Forward-declare the class hierarchy descriptor
3766 auto Type = ABI.getClassHierarchyDescriptorType();
3767 auto CHD = new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage,
3768 /*Initializer=*/nullptr,
3769 MangledName);
3770 if (CHD->isWeakForLinker())
3771 CHD->setComdat(CGM.getModule().getOrInsertComdat(CHD->getName()));
3772
3773 auto *Bases = getBaseClassArray(Classes);
3774
3775 // Initialize the base class ClassHierarchyDescriptor.
3776 llvm::Constant *Fields[] = {
3777 llvm::ConstantInt::get(CGM.IntTy, 0), // reserved by the runtime
3778 llvm::ConstantInt::get(CGM.IntTy, Flags),
3779 llvm::ConstantInt::get(CGM.IntTy, Classes.size()),
3780 ABI.getImageRelativeConstant(llvm::ConstantExpr::getInBoundsGetElementPtr(
3781 Bases->getValueType(), Bases,
3782 llvm::ArrayRef<llvm::Value *>(GEPIndices))),
3783 };
3784 CHD->setInitializer(llvm::ConstantStruct::get(Type, Fields));
3785 return CHD;
3786 }
3787
3788 llvm::GlobalVariable *
getBaseClassArray(SmallVectorImpl<MSRTTIClass> & Classes)3789 MSRTTIBuilder::getBaseClassArray(SmallVectorImpl<MSRTTIClass> &Classes) {
3790 SmallString<256> MangledName;
3791 {
3792 llvm::raw_svector_ostream Out(MangledName);
3793 ABI.getMangleContext().mangleCXXRTTIBaseClassArray(RD, Out);
3794 }
3795
3796 // Forward-declare the base class array.
3797 // cl.exe pads the base class array with 1 (in 32 bit mode) or 4 (in 64 bit
3798 // mode) bytes of padding. We provide a pointer sized amount of padding by
3799 // adding +1 to Classes.size(). The sections have pointer alignment and are
3800 // marked pick-any so it shouldn't matter.
3801 llvm::Type *PtrType = ABI.getImageRelativeType(
3802 ABI.getBaseClassDescriptorType()->getPointerTo());
3803 auto *ArrType = llvm::ArrayType::get(PtrType, Classes.size() + 1);
3804 auto *BCA =
3805 new llvm::GlobalVariable(Module, ArrType,
3806 /*isConstant=*/true, Linkage,
3807 /*Initializer=*/nullptr, MangledName);
3808 if (BCA->isWeakForLinker())
3809 BCA->setComdat(CGM.getModule().getOrInsertComdat(BCA->getName()));
3810
3811 // Initialize the BaseClassArray.
3812 SmallVector<llvm::Constant *, 8> BaseClassArrayData;
3813 for (MSRTTIClass &Class : Classes)
3814 BaseClassArrayData.push_back(
3815 ABI.getImageRelativeConstant(getBaseClassDescriptor(Class)));
3816 BaseClassArrayData.push_back(llvm::Constant::getNullValue(PtrType));
3817 BCA->setInitializer(llvm::ConstantArray::get(ArrType, BaseClassArrayData));
3818 return BCA;
3819 }
3820
3821 llvm::GlobalVariable *
getBaseClassDescriptor(const MSRTTIClass & Class)3822 MSRTTIBuilder::getBaseClassDescriptor(const MSRTTIClass &Class) {
3823 // Compute the fields for the BaseClassDescriptor. They are computed up front
3824 // because they are mangled into the name of the object.
3825 uint32_t OffsetInVBTable = 0;
3826 int32_t VBPtrOffset = -1;
3827 if (Class.VirtualRoot) {
3828 auto &VTableContext = CGM.getMicrosoftVTableContext();
3829 OffsetInVBTable = VTableContext.getVBTableIndex(RD, Class.VirtualRoot) * 4;
3830 VBPtrOffset = Context.getASTRecordLayout(RD).getVBPtrOffset().getQuantity();
3831 }
3832
3833 SmallString<256> MangledName;
3834 {
3835 llvm::raw_svector_ostream Out(MangledName);
3836 ABI.getMangleContext().mangleCXXRTTIBaseClassDescriptor(
3837 Class.RD, Class.OffsetInVBase, VBPtrOffset, OffsetInVBTable,
3838 Class.Flags, Out);
3839 }
3840
3841 // Check to see if we've already declared this object.
3842 if (auto BCD = Module.getNamedGlobal(MangledName))
3843 return BCD;
3844
3845 // Forward-declare the base class descriptor.
3846 auto Type = ABI.getBaseClassDescriptorType();
3847 auto BCD =
3848 new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage,
3849 /*Initializer=*/nullptr, MangledName);
3850 if (BCD->isWeakForLinker())
3851 BCD->setComdat(CGM.getModule().getOrInsertComdat(BCD->getName()));
3852
3853 // Initialize the BaseClassDescriptor.
3854 llvm::Constant *Fields[] = {
3855 ABI.getImageRelativeConstant(
3856 ABI.getAddrOfRTTIDescriptor(Context.getTypeDeclType(Class.RD))),
3857 llvm::ConstantInt::get(CGM.IntTy, Class.NumBases),
3858 llvm::ConstantInt::get(CGM.IntTy, Class.OffsetInVBase),
3859 llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset),
3860 llvm::ConstantInt::get(CGM.IntTy, OffsetInVBTable),
3861 llvm::ConstantInt::get(CGM.IntTy, Class.Flags),
3862 ABI.getImageRelativeConstant(
3863 MSRTTIBuilder(ABI, Class.RD).getClassHierarchyDescriptor()),
3864 };
3865 BCD->setInitializer(llvm::ConstantStruct::get(Type, Fields));
3866 return BCD;
3867 }
3868
3869 llvm::GlobalVariable *
getCompleteObjectLocator(const VPtrInfo & Info)3870 MSRTTIBuilder::getCompleteObjectLocator(const VPtrInfo &Info) {
3871 SmallString<256> MangledName;
3872 {
3873 llvm::raw_svector_ostream Out(MangledName);
3874 ABI.getMangleContext().mangleCXXRTTICompleteObjectLocator(RD, Info.MangledPath, Out);
3875 }
3876
3877 // Check to see if we've already computed this complete object locator.
3878 if (auto COL = Module.getNamedGlobal(MangledName))
3879 return COL;
3880
3881 // Compute the fields of the complete object locator.
3882 int OffsetToTop = Info.FullOffsetInMDC.getQuantity();
3883 int VFPtrOffset = 0;
3884 // The offset includes the vtordisp if one exists.
3885 if (const CXXRecordDecl *VBase = Info.getVBaseWithVPtr())
3886 if (Context.getASTRecordLayout(RD)
3887 .getVBaseOffsetsMap()
3888 .find(VBase)
3889 ->second.hasVtorDisp())
3890 VFPtrOffset = Info.NonVirtualOffset.getQuantity() + 4;
3891
3892 // Forward-declare the complete object locator.
3893 llvm::StructType *Type = ABI.getCompleteObjectLocatorType();
3894 auto COL = new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage,
3895 /*Initializer=*/nullptr, MangledName);
3896
3897 // Initialize the CompleteObjectLocator.
3898 llvm::Constant *Fields[] = {
3899 llvm::ConstantInt::get(CGM.IntTy, ABI.isImageRelative()),
3900 llvm::ConstantInt::get(CGM.IntTy, OffsetToTop),
3901 llvm::ConstantInt::get(CGM.IntTy, VFPtrOffset),
3902 ABI.getImageRelativeConstant(
3903 CGM.GetAddrOfRTTIDescriptor(Context.getTypeDeclType(RD))),
3904 ABI.getImageRelativeConstant(getClassHierarchyDescriptor()),
3905 ABI.getImageRelativeConstant(COL),
3906 };
3907 llvm::ArrayRef<llvm::Constant *> FieldsRef(Fields);
3908 if (!ABI.isImageRelative())
3909 FieldsRef = FieldsRef.drop_back();
3910 COL->setInitializer(llvm::ConstantStruct::get(Type, FieldsRef));
3911 if (COL->isWeakForLinker())
3912 COL->setComdat(CGM.getModule().getOrInsertComdat(COL->getName()));
3913 return COL;
3914 }
3915
decomposeTypeForEH(ASTContext & Context,QualType T,bool & IsConst,bool & IsVolatile,bool & IsUnaligned)3916 static QualType decomposeTypeForEH(ASTContext &Context, QualType T,
3917 bool &IsConst, bool &IsVolatile,
3918 bool &IsUnaligned) {
3919 T = Context.getExceptionObjectType(T);
3920
3921 // C++14 [except.handle]p3:
3922 // A handler is a match for an exception object of type E if [...]
3923 // - the handler is of type cv T or const T& where T is a pointer type and
3924 // E is a pointer type that can be converted to T by [...]
3925 // - a qualification conversion
3926 IsConst = false;
3927 IsVolatile = false;
3928 IsUnaligned = false;
3929 QualType PointeeType = T->getPointeeType();
3930 if (!PointeeType.isNull()) {
3931 IsConst = PointeeType.isConstQualified();
3932 IsVolatile = PointeeType.isVolatileQualified();
3933 IsUnaligned = PointeeType.getQualifiers().hasUnaligned();
3934 }
3935
3936 // Member pointer types like "const int A::*" are represented by having RTTI
3937 // for "int A::*" and separately storing the const qualifier.
3938 if (const auto *MPTy = T->getAs<MemberPointerType>())
3939 T = Context.getMemberPointerType(PointeeType.getUnqualifiedType(),
3940 MPTy->getClass());
3941
3942 // Pointer types like "const int * const *" are represented by having RTTI
3943 // for "const int **" and separately storing the const qualifier.
3944 if (T->isPointerType())
3945 T = Context.getPointerType(PointeeType.getUnqualifiedType());
3946
3947 return T;
3948 }
3949
3950 CatchTypeInfo
getAddrOfCXXCatchHandlerType(QualType Type,QualType CatchHandlerType)3951 MicrosoftCXXABI::getAddrOfCXXCatchHandlerType(QualType Type,
3952 QualType CatchHandlerType) {
3953 // TypeDescriptors for exceptions never have qualified pointer types,
3954 // qualifiers are stored separately in order to support qualification
3955 // conversions.
3956 bool IsConst, IsVolatile, IsUnaligned;
3957 Type =
3958 decomposeTypeForEH(getContext(), Type, IsConst, IsVolatile, IsUnaligned);
3959
3960 bool IsReference = CatchHandlerType->isReferenceType();
3961
3962 uint32_t Flags = 0;
3963 if (IsConst)
3964 Flags |= 1;
3965 if (IsVolatile)
3966 Flags |= 2;
3967 if (IsUnaligned)
3968 Flags |= 4;
3969 if (IsReference)
3970 Flags |= 8;
3971
3972 return CatchTypeInfo{getAddrOfRTTIDescriptor(Type)->stripPointerCasts(),
3973 Flags};
3974 }
3975
3976 /// Gets a TypeDescriptor. Returns a llvm::Constant * rather than a
3977 /// llvm::GlobalVariable * because different type descriptors have different
3978 /// types, and need to be abstracted. They are abstracting by casting the
3979 /// address to an Int8PtrTy.
getAddrOfRTTIDescriptor(QualType Type)3980 llvm::Constant *MicrosoftCXXABI::getAddrOfRTTIDescriptor(QualType Type) {
3981 SmallString<256> MangledName;
3982 {
3983 llvm::raw_svector_ostream Out(MangledName);
3984 getMangleContext().mangleCXXRTTI(Type, Out);
3985 }
3986
3987 // Check to see if we've already declared this TypeDescriptor.
3988 if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName))
3989 return GV;
3990
3991 // Note for the future: If we would ever like to do deferred emission of
3992 // RTTI, check if emitting vtables opportunistically need any adjustment.
3993
3994 // Compute the fields for the TypeDescriptor.
3995 SmallString<256> TypeInfoString;
3996 {
3997 llvm::raw_svector_ostream Out(TypeInfoString);
3998 getMangleContext().mangleCXXRTTIName(Type, Out);
3999 }
4000
4001 // Declare and initialize the TypeDescriptor.
4002 llvm::Constant *Fields[] = {
4003 getTypeInfoVTable(CGM), // VFPtr
4004 llvm::ConstantPointerNull::get(CGM.Int8PtrTy), // Runtime data
4005 llvm::ConstantDataArray::getString(CGM.getLLVMContext(), TypeInfoString)};
4006 llvm::StructType *TypeDescriptorType =
4007 getTypeDescriptorType(TypeInfoString);
4008 auto *Var = new llvm::GlobalVariable(
4009 CGM.getModule(), TypeDescriptorType, /*isConstant=*/false,
4010 getLinkageForRTTI(Type),
4011 llvm::ConstantStruct::get(TypeDescriptorType, Fields),
4012 MangledName);
4013 if (Var->isWeakForLinker())
4014 Var->setComdat(CGM.getModule().getOrInsertComdat(Var->getName()));
4015 return Var;
4016 }
4017
4018 /// Gets or a creates a Microsoft CompleteObjectLocator.
4019 llvm::GlobalVariable *
getMSCompleteObjectLocator(const CXXRecordDecl * RD,const VPtrInfo & Info)4020 MicrosoftCXXABI::getMSCompleteObjectLocator(const CXXRecordDecl *RD,
4021 const VPtrInfo &Info) {
4022 return MSRTTIBuilder(*this, RD).getCompleteObjectLocator(Info);
4023 }
4024
emitCXXStructor(GlobalDecl GD)4025 void MicrosoftCXXABI::emitCXXStructor(GlobalDecl GD) {
4026 if (auto *ctor = dyn_cast<CXXConstructorDecl>(GD.getDecl())) {
4027 // There are no constructor variants, always emit the complete destructor.
4028 llvm::Function *Fn =
4029 CGM.codegenCXXStructor(GD.getWithCtorType(Ctor_Complete));
4030 CGM.maybeSetTrivialComdat(*ctor, *Fn);
4031 return;
4032 }
4033
4034 auto *dtor = cast<CXXDestructorDecl>(GD.getDecl());
4035
4036 // Emit the base destructor if the base and complete (vbase) destructors are
4037 // equivalent. This effectively implements -mconstructor-aliases as part of
4038 // the ABI.
4039 if (GD.getDtorType() == Dtor_Complete &&
4040 dtor->getParent()->getNumVBases() == 0)
4041 GD = GD.getWithDtorType(Dtor_Base);
4042
4043 // The base destructor is equivalent to the base destructor of its
4044 // base class if there is exactly one non-virtual base class with a
4045 // non-trivial destructor, there are no fields with a non-trivial
4046 // destructor, and the body of the destructor is trivial.
4047 if (GD.getDtorType() == Dtor_Base && !CGM.TryEmitBaseDestructorAsAlias(dtor))
4048 return;
4049
4050 llvm::Function *Fn = CGM.codegenCXXStructor(GD);
4051 if (Fn->isWeakForLinker())
4052 Fn->setComdat(CGM.getModule().getOrInsertComdat(Fn->getName()));
4053 }
4054
4055 llvm::Function *
getAddrOfCXXCtorClosure(const CXXConstructorDecl * CD,CXXCtorType CT)4056 MicrosoftCXXABI::getAddrOfCXXCtorClosure(const CXXConstructorDecl *CD,
4057 CXXCtorType CT) {
4058 assert(CT == Ctor_CopyingClosure || CT == Ctor_DefaultClosure);
4059
4060 // Calculate the mangled name.
4061 SmallString<256> ThunkName;
4062 llvm::raw_svector_ostream Out(ThunkName);
4063 getMangleContext().mangleName(GlobalDecl(CD, CT), Out);
4064
4065 // If the thunk has been generated previously, just return it.
4066 if (llvm::GlobalValue *GV = CGM.getModule().getNamedValue(ThunkName))
4067 return cast<llvm::Function>(GV);
4068
4069 // Create the llvm::Function.
4070 const CGFunctionInfo &FnInfo = CGM.getTypes().arrangeMSCtorClosure(CD, CT);
4071 llvm::FunctionType *ThunkTy = CGM.getTypes().GetFunctionType(FnInfo);
4072 const CXXRecordDecl *RD = CD->getParent();
4073 QualType RecordTy = getContext().getRecordType(RD);
4074 llvm::Function *ThunkFn = llvm::Function::Create(
4075 ThunkTy, getLinkageForRTTI(RecordTy), ThunkName.str(), &CGM.getModule());
4076 ThunkFn->setCallingConv(static_cast<llvm::CallingConv::ID>(
4077 FnInfo.getEffectiveCallingConvention()));
4078 if (ThunkFn->isWeakForLinker())
4079 ThunkFn->setComdat(CGM.getModule().getOrInsertComdat(ThunkFn->getName()));
4080 bool IsCopy = CT == Ctor_CopyingClosure;
4081
4082 // Start codegen.
4083 CodeGenFunction CGF(CGM);
4084 CGF.CurGD = GlobalDecl(CD, Ctor_Complete);
4085
4086 // Build FunctionArgs.
4087 FunctionArgList FunctionArgs;
4088
4089 // A constructor always starts with a 'this' pointer as its first argument.
4090 buildThisParam(CGF, FunctionArgs);
4091
4092 // Following the 'this' pointer is a reference to the source object that we
4093 // are copying from.
4094 ImplicitParamDecl SrcParam(
4095 getContext(), /*DC=*/nullptr, SourceLocation(),
4096 &getContext().Idents.get("src"),
4097 getContext().getLValueReferenceType(RecordTy,
4098 /*SpelledAsLValue=*/true),
4099 ImplicitParamKind::Other);
4100 if (IsCopy)
4101 FunctionArgs.push_back(&SrcParam);
4102
4103 // Constructors for classes which utilize virtual bases have an additional
4104 // parameter which indicates whether or not it is being delegated to by a more
4105 // derived constructor.
4106 ImplicitParamDecl IsMostDerived(getContext(), /*DC=*/nullptr,
4107 SourceLocation(),
4108 &getContext().Idents.get("is_most_derived"),
4109 getContext().IntTy, ImplicitParamKind::Other);
4110 // Only add the parameter to the list if the class has virtual bases.
4111 if (RD->getNumVBases() > 0)
4112 FunctionArgs.push_back(&IsMostDerived);
4113
4114 // Start defining the function.
4115 auto NL = ApplyDebugLocation::CreateEmpty(CGF);
4116 CGF.StartFunction(GlobalDecl(), FnInfo.getReturnType(), ThunkFn, FnInfo,
4117 FunctionArgs, CD->getLocation(), SourceLocation());
4118 // Create a scope with an artificial location for the body of this function.
4119 auto AL = ApplyDebugLocation::CreateArtificial(CGF);
4120 setCXXABIThisValue(CGF, loadIncomingCXXThis(CGF));
4121 llvm::Value *This = getThisValue(CGF);
4122
4123 llvm::Value *SrcVal =
4124 IsCopy ? CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(&SrcParam), "src")
4125 : nullptr;
4126
4127 CallArgList Args;
4128
4129 // Push the this ptr.
4130 Args.add(RValue::get(This), CD->getThisType());
4131
4132 // Push the src ptr.
4133 if (SrcVal)
4134 Args.add(RValue::get(SrcVal), SrcParam.getType());
4135
4136 // Add the rest of the default arguments.
4137 SmallVector<const Stmt *, 4> ArgVec;
4138 ArrayRef<ParmVarDecl *> params = CD->parameters().drop_front(IsCopy ? 1 : 0);
4139 for (const ParmVarDecl *PD : params) {
4140 assert(PD->hasDefaultArg() && "ctor closure lacks default args");
4141 ArgVec.push_back(PD->getDefaultArg());
4142 }
4143
4144 CodeGenFunction::RunCleanupsScope Cleanups(CGF);
4145
4146 const auto *FPT = CD->getType()->castAs<FunctionProtoType>();
4147 CGF.EmitCallArgs(Args, FPT, llvm::ArrayRef(ArgVec), CD, IsCopy ? 1 : 0);
4148
4149 // Insert any ABI-specific implicit constructor arguments.
4150 AddedStructorArgCounts ExtraArgs =
4151 addImplicitConstructorArgs(CGF, CD, Ctor_Complete,
4152 /*ForVirtualBase=*/false,
4153 /*Delegating=*/false, Args);
4154 // Call the destructor with our arguments.
4155 llvm::Constant *CalleePtr =
4156 CGM.getAddrOfCXXStructor(GlobalDecl(CD, Ctor_Complete));
4157 CGCallee Callee =
4158 CGCallee::forDirect(CalleePtr, GlobalDecl(CD, Ctor_Complete));
4159 const CGFunctionInfo &CalleeInfo = CGM.getTypes().arrangeCXXConstructorCall(
4160 Args, CD, Ctor_Complete, ExtraArgs.Prefix, ExtraArgs.Suffix);
4161 CGF.EmitCall(CalleeInfo, Callee, ReturnValueSlot(), Args);
4162
4163 Cleanups.ForceCleanup();
4164
4165 // Emit the ret instruction, remove any temporary instructions created for the
4166 // aid of CodeGen.
4167 CGF.FinishFunction(SourceLocation());
4168
4169 return ThunkFn;
4170 }
4171
getCatchableType(QualType T,uint32_t NVOffset,int32_t VBPtrOffset,uint32_t VBIndex)4172 llvm::Constant *MicrosoftCXXABI::getCatchableType(QualType T,
4173 uint32_t NVOffset,
4174 int32_t VBPtrOffset,
4175 uint32_t VBIndex) {
4176 assert(!T->isReferenceType());
4177
4178 CXXRecordDecl *RD = T->getAsCXXRecordDecl();
4179 const CXXConstructorDecl *CD =
4180 RD ? CGM.getContext().getCopyConstructorForExceptionObject(RD) : nullptr;
4181 CXXCtorType CT = Ctor_Complete;
4182 if (CD)
4183 if (!hasDefaultCXXMethodCC(getContext(), CD) || CD->getNumParams() != 1)
4184 CT = Ctor_CopyingClosure;
4185
4186 uint32_t Size = getContext().getTypeSizeInChars(T).getQuantity();
4187 SmallString<256> MangledName;
4188 {
4189 llvm::raw_svector_ostream Out(MangledName);
4190 getMangleContext().mangleCXXCatchableType(T, CD, CT, Size, NVOffset,
4191 VBPtrOffset, VBIndex, Out);
4192 }
4193 if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName))
4194 return getImageRelativeConstant(GV);
4195
4196 // The TypeDescriptor is used by the runtime to determine if a catch handler
4197 // is appropriate for the exception object.
4198 llvm::Constant *TD = getImageRelativeConstant(getAddrOfRTTIDescriptor(T));
4199
4200 // The runtime is responsible for calling the copy constructor if the
4201 // exception is caught by value.
4202 llvm::Constant *CopyCtor;
4203 if (CD) {
4204 if (CT == Ctor_CopyingClosure)
4205 CopyCtor = getAddrOfCXXCtorClosure(CD, Ctor_CopyingClosure);
4206 else
4207 CopyCtor = CGM.getAddrOfCXXStructor(GlobalDecl(CD, Ctor_Complete));
4208 } else {
4209 CopyCtor = llvm::Constant::getNullValue(CGM.Int8PtrTy);
4210 }
4211 CopyCtor = getImageRelativeConstant(CopyCtor);
4212
4213 bool IsScalar = !RD;
4214 bool HasVirtualBases = false;
4215 bool IsStdBadAlloc = false; // std::bad_alloc is special for some reason.
4216 QualType PointeeType = T;
4217 if (T->isPointerType())
4218 PointeeType = T->getPointeeType();
4219 if (const CXXRecordDecl *RD = PointeeType->getAsCXXRecordDecl()) {
4220 HasVirtualBases = RD->getNumVBases() > 0;
4221 if (IdentifierInfo *II = RD->getIdentifier())
4222 IsStdBadAlloc = II->isStr("bad_alloc") && RD->isInStdNamespace();
4223 }
4224
4225 // Encode the relevant CatchableType properties into the Flags bitfield.
4226 // FIXME: Figure out how bits 2 or 8 can get set.
4227 uint32_t Flags = 0;
4228 if (IsScalar)
4229 Flags |= 1;
4230 if (HasVirtualBases)
4231 Flags |= 4;
4232 if (IsStdBadAlloc)
4233 Flags |= 16;
4234
4235 llvm::Constant *Fields[] = {
4236 llvm::ConstantInt::get(CGM.IntTy, Flags), // Flags
4237 TD, // TypeDescriptor
4238 llvm::ConstantInt::get(CGM.IntTy, NVOffset), // NonVirtualAdjustment
4239 llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset), // OffsetToVBPtr
4240 llvm::ConstantInt::get(CGM.IntTy, VBIndex), // VBTableIndex
4241 llvm::ConstantInt::get(CGM.IntTy, Size), // Size
4242 CopyCtor // CopyCtor
4243 };
4244 llvm::StructType *CTType = getCatchableTypeType();
4245 auto *GV = new llvm::GlobalVariable(
4246 CGM.getModule(), CTType, /*isConstant=*/true, getLinkageForRTTI(T),
4247 llvm::ConstantStruct::get(CTType, Fields), MangledName);
4248 GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
4249 GV->setSection(".xdata");
4250 if (GV->isWeakForLinker())
4251 GV->setComdat(CGM.getModule().getOrInsertComdat(GV->getName()));
4252 return getImageRelativeConstant(GV);
4253 }
4254
getCatchableTypeArray(QualType T)4255 llvm::GlobalVariable *MicrosoftCXXABI::getCatchableTypeArray(QualType T) {
4256 assert(!T->isReferenceType());
4257
4258 // See if we've already generated a CatchableTypeArray for this type before.
4259 llvm::GlobalVariable *&CTA = CatchableTypeArrays[T];
4260 if (CTA)
4261 return CTA;
4262
4263 // Ensure that we don't have duplicate entries in our CatchableTypeArray by
4264 // using a SmallSetVector. Duplicates may arise due to virtual bases
4265 // occurring more than once in the hierarchy.
4266 llvm::SmallSetVector<llvm::Constant *, 2> CatchableTypes;
4267
4268 // C++14 [except.handle]p3:
4269 // A handler is a match for an exception object of type E if [...]
4270 // - the handler is of type cv T or cv T& and T is an unambiguous public
4271 // base class of E, or
4272 // - the handler is of type cv T or const T& where T is a pointer type and
4273 // E is a pointer type that can be converted to T by [...]
4274 // - a standard pointer conversion (4.10) not involving conversions to
4275 // pointers to private or protected or ambiguous classes
4276 const CXXRecordDecl *MostDerivedClass = nullptr;
4277 bool IsPointer = T->isPointerType();
4278 if (IsPointer)
4279 MostDerivedClass = T->getPointeeType()->getAsCXXRecordDecl();
4280 else
4281 MostDerivedClass = T->getAsCXXRecordDecl();
4282
4283 // Collect all the unambiguous public bases of the MostDerivedClass.
4284 if (MostDerivedClass) {
4285 const ASTContext &Context = getContext();
4286 const ASTRecordLayout &MostDerivedLayout =
4287 Context.getASTRecordLayout(MostDerivedClass);
4288 MicrosoftVTableContext &VTableContext = CGM.getMicrosoftVTableContext();
4289 SmallVector<MSRTTIClass, 8> Classes;
4290 serializeClassHierarchy(Classes, MostDerivedClass);
4291 Classes.front().initialize(/*Parent=*/nullptr, /*Specifier=*/nullptr);
4292 detectAmbiguousBases(Classes);
4293 for (const MSRTTIClass &Class : Classes) {
4294 // Skip any ambiguous or private bases.
4295 if (Class.Flags &
4296 (MSRTTIClass::IsPrivateOnPath | MSRTTIClass::IsAmbiguous))
4297 continue;
4298 // Write down how to convert from a derived pointer to a base pointer.
4299 uint32_t OffsetInVBTable = 0;
4300 int32_t VBPtrOffset = -1;
4301 if (Class.VirtualRoot) {
4302 OffsetInVBTable =
4303 VTableContext.getVBTableIndex(MostDerivedClass, Class.VirtualRoot)*4;
4304 VBPtrOffset = MostDerivedLayout.getVBPtrOffset().getQuantity();
4305 }
4306
4307 // Turn our record back into a pointer if the exception object is a
4308 // pointer.
4309 QualType RTTITy = QualType(Class.RD->getTypeForDecl(), 0);
4310 if (IsPointer)
4311 RTTITy = Context.getPointerType(RTTITy);
4312 CatchableTypes.insert(getCatchableType(RTTITy, Class.OffsetInVBase,
4313 VBPtrOffset, OffsetInVBTable));
4314 }
4315 }
4316
4317 // C++14 [except.handle]p3:
4318 // A handler is a match for an exception object of type E if
4319 // - The handler is of type cv T or cv T& and E and T are the same type
4320 // (ignoring the top-level cv-qualifiers)
4321 CatchableTypes.insert(getCatchableType(T));
4322
4323 // C++14 [except.handle]p3:
4324 // A handler is a match for an exception object of type E if
4325 // - the handler is of type cv T or const T& where T is a pointer type and
4326 // E is a pointer type that can be converted to T by [...]
4327 // - a standard pointer conversion (4.10) not involving conversions to
4328 // pointers to private or protected or ambiguous classes
4329 //
4330 // C++14 [conv.ptr]p2:
4331 // A prvalue of type "pointer to cv T," where T is an object type, can be
4332 // converted to a prvalue of type "pointer to cv void".
4333 if (IsPointer && T->getPointeeType()->isObjectType())
4334 CatchableTypes.insert(getCatchableType(getContext().VoidPtrTy));
4335
4336 // C++14 [except.handle]p3:
4337 // A handler is a match for an exception object of type E if [...]
4338 // - the handler is of type cv T or const T& where T is a pointer or
4339 // pointer to member type and E is std::nullptr_t.
4340 //
4341 // We cannot possibly list all possible pointer types here, making this
4342 // implementation incompatible with the standard. However, MSVC includes an
4343 // entry for pointer-to-void in this case. Let's do the same.
4344 if (T->isNullPtrType())
4345 CatchableTypes.insert(getCatchableType(getContext().VoidPtrTy));
4346
4347 uint32_t NumEntries = CatchableTypes.size();
4348 llvm::Type *CTType =
4349 getImageRelativeType(getCatchableTypeType()->getPointerTo());
4350 llvm::ArrayType *AT = llvm::ArrayType::get(CTType, NumEntries);
4351 llvm::StructType *CTAType = getCatchableTypeArrayType(NumEntries);
4352 llvm::Constant *Fields[] = {
4353 llvm::ConstantInt::get(CGM.IntTy, NumEntries), // NumEntries
4354 llvm::ConstantArray::get(
4355 AT, llvm::ArrayRef(CatchableTypes.begin(),
4356 CatchableTypes.end())) // CatchableTypes
4357 };
4358 SmallString<256> MangledName;
4359 {
4360 llvm::raw_svector_ostream Out(MangledName);
4361 getMangleContext().mangleCXXCatchableTypeArray(T, NumEntries, Out);
4362 }
4363 CTA = new llvm::GlobalVariable(
4364 CGM.getModule(), CTAType, /*isConstant=*/true, getLinkageForRTTI(T),
4365 llvm::ConstantStruct::get(CTAType, Fields), MangledName);
4366 CTA->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
4367 CTA->setSection(".xdata");
4368 if (CTA->isWeakForLinker())
4369 CTA->setComdat(CGM.getModule().getOrInsertComdat(CTA->getName()));
4370 return CTA;
4371 }
4372
getThrowInfo(QualType T)4373 llvm::GlobalVariable *MicrosoftCXXABI::getThrowInfo(QualType T) {
4374 bool IsConst, IsVolatile, IsUnaligned;
4375 T = decomposeTypeForEH(getContext(), T, IsConst, IsVolatile, IsUnaligned);
4376
4377 // The CatchableTypeArray enumerates the various (CV-unqualified) types that
4378 // the exception object may be caught as.
4379 llvm::GlobalVariable *CTA = getCatchableTypeArray(T);
4380 // The first field in a CatchableTypeArray is the number of CatchableTypes.
4381 // This is used as a component of the mangled name which means that we need to
4382 // know what it is in order to see if we have previously generated the
4383 // ThrowInfo.
4384 uint32_t NumEntries =
4385 cast<llvm::ConstantInt>(CTA->getInitializer()->getAggregateElement(0U))
4386 ->getLimitedValue();
4387
4388 SmallString<256> MangledName;
4389 {
4390 llvm::raw_svector_ostream Out(MangledName);
4391 getMangleContext().mangleCXXThrowInfo(T, IsConst, IsVolatile, IsUnaligned,
4392 NumEntries, Out);
4393 }
4394
4395 // Reuse a previously generated ThrowInfo if we have generated an appropriate
4396 // one before.
4397 if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName))
4398 return GV;
4399
4400 // The RTTI TypeDescriptor uses an unqualified type but catch clauses must
4401 // be at least as CV qualified. Encode this requirement into the Flags
4402 // bitfield.
4403 uint32_t Flags = 0;
4404 if (IsConst)
4405 Flags |= 1;
4406 if (IsVolatile)
4407 Flags |= 2;
4408 if (IsUnaligned)
4409 Flags |= 4;
4410
4411 // The cleanup-function (a destructor) must be called when the exception
4412 // object's lifetime ends.
4413 llvm::Constant *CleanupFn = llvm::Constant::getNullValue(CGM.Int8PtrTy);
4414 if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
4415 if (CXXDestructorDecl *DtorD = RD->getDestructor())
4416 if (!DtorD->isTrivial())
4417 CleanupFn = CGM.getAddrOfCXXStructor(GlobalDecl(DtorD, Dtor_Complete));
4418 // This is unused as far as we can tell, initialize it to null.
4419 llvm::Constant *ForwardCompat =
4420 getImageRelativeConstant(llvm::Constant::getNullValue(CGM.Int8PtrTy));
4421 llvm::Constant *PointerToCatchableTypes = getImageRelativeConstant(CTA);
4422 llvm::StructType *TIType = getThrowInfoType();
4423 llvm::Constant *Fields[] = {
4424 llvm::ConstantInt::get(CGM.IntTy, Flags), // Flags
4425 getImageRelativeConstant(CleanupFn), // CleanupFn
4426 ForwardCompat, // ForwardCompat
4427 PointerToCatchableTypes // CatchableTypeArray
4428 };
4429 auto *GV = new llvm::GlobalVariable(
4430 CGM.getModule(), TIType, /*isConstant=*/true, getLinkageForRTTI(T),
4431 llvm::ConstantStruct::get(TIType, Fields), MangledName.str());
4432 GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
4433 GV->setSection(".xdata");
4434 if (GV->isWeakForLinker())
4435 GV->setComdat(CGM.getModule().getOrInsertComdat(GV->getName()));
4436 return GV;
4437 }
4438
emitThrow(CodeGenFunction & CGF,const CXXThrowExpr * E)4439 void MicrosoftCXXABI::emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) {
4440 const Expr *SubExpr = E->getSubExpr();
4441 assert(SubExpr && "SubExpr cannot be null");
4442 QualType ThrowType = SubExpr->getType();
4443 // The exception object lives on the stack and it's address is passed to the
4444 // runtime function.
4445 Address AI = CGF.CreateMemTemp(ThrowType);
4446 CGF.EmitAnyExprToMem(SubExpr, AI, ThrowType.getQualifiers(),
4447 /*IsInit=*/true);
4448
4449 // The so-called ThrowInfo is used to describe how the exception object may be
4450 // caught.
4451 llvm::GlobalVariable *TI = getThrowInfo(ThrowType);
4452
4453 // Call into the runtime to throw the exception.
4454 llvm::Value *Args[] = {
4455 AI.getPointer(),
4456 TI
4457 };
4458 CGF.EmitNoreturnRuntimeCallOrInvoke(getThrowFn(), Args);
4459 }
4460
4461 std::pair<llvm::Value *, const CXXRecordDecl *>
LoadVTablePtr(CodeGenFunction & CGF,Address This,const CXXRecordDecl * RD)4462 MicrosoftCXXABI::LoadVTablePtr(CodeGenFunction &CGF, Address This,
4463 const CXXRecordDecl *RD) {
4464 std::tie(This, std::ignore, RD) =
4465 performBaseAdjustment(CGF, This, QualType(RD->getTypeForDecl(), 0));
4466 return {CGF.GetVTablePtr(This, CGM.Int8PtrTy, RD), RD};
4467 }
4468
isPermittedToBeHomogeneousAggregate(const CXXRecordDecl * RD) const4469 bool MicrosoftCXXABI::isPermittedToBeHomogeneousAggregate(
4470 const CXXRecordDecl *RD) const {
4471 // All aggregates are permitted to be HFA on non-ARM platforms, which mostly
4472 // affects vectorcall on x64/x86.
4473 if (!CGM.getTarget().getTriple().isAArch64())
4474 return true;
4475 // MSVC Windows on Arm64 has its own rules for determining if a type is HFA
4476 // that are inconsistent with the AAPCS64 ABI. The following are our best
4477 // determination of those rules so far, based on observation of MSVC's
4478 // behavior.
4479 if (RD->isEmpty())
4480 return false;
4481 if (RD->isPolymorphic())
4482 return false;
4483 if (RD->hasNonTrivialCopyAssignment())
4484 return false;
4485 if (RD->hasNonTrivialDestructor())
4486 return false;
4487 if (RD->hasNonTrivialDefaultConstructor())
4488 return false;
4489 // These two are somewhat redundant given the caller
4490 // (ABIInfo::isHomogeneousAggregate) checks the bases and fields, but that
4491 // caller doesn't consider empty bases/fields to be non-homogenous, but it
4492 // looks like Microsoft's AArch64 ABI does care about these empty types &
4493 // anything containing/derived from one is non-homogeneous.
4494 // Instead we could add another CXXABI entry point to query this property and
4495 // have ABIInfo::isHomogeneousAggregate use that property.
4496 // I don't think any other of the features listed above could be true of a
4497 // base/field while not true of the outer struct. For example, if you have a
4498 // base/field that has an non-trivial copy assignment/dtor/default ctor, then
4499 // the outer struct's corresponding operation must be non-trivial.
4500 for (const CXXBaseSpecifier &B : RD->bases()) {
4501 if (const CXXRecordDecl *FRD = B.getType()->getAsCXXRecordDecl()) {
4502 if (!isPermittedToBeHomogeneousAggregate(FRD))
4503 return false;
4504 }
4505 }
4506 // empty fields seem to be caught by the ABIInfo::isHomogeneousAggregate
4507 // checking for padding - but maybe there are ways to end up with an empty
4508 // field without padding? Not that I know of, so don't check fields here &
4509 // rely on the padding check.
4510 return true;
4511 }
4512