1 //===--- MicrosoftCXXABI.cpp - Emit LLVM Code from ASTs for a Module ------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This provides C++ code generation targeting the Microsoft Visual C++ ABI.
10 // The class in this file generates structures that follow the Microsoft
11 // Visual C++ ABI, which is actually not very well documented at all outside
12 // of Microsoft.
13 //
14 //===----------------------------------------------------------------------===//
15
16 #include "CGCXXABI.h"
17 #include "CGCleanup.h"
18 #include "CGVTables.h"
19 #include "CodeGenModule.h"
20 #include "CodeGenTypes.h"
21 #include "TargetInfo.h"
22 #include "clang/AST/Attr.h"
23 #include "clang/AST/CXXInheritance.h"
24 #include "clang/AST/Decl.h"
25 #include "clang/AST/DeclCXX.h"
26 #include "clang/AST/StmtCXX.h"
27 #include "clang/AST/VTableBuilder.h"
28 #include "clang/CodeGen/ConstantInitBuilder.h"
29 #include "llvm/ADT/StringExtras.h"
30 #include "llvm/ADT/StringSet.h"
31 #include "llvm/IR/Intrinsics.h"
32
33 using namespace clang;
34 using namespace CodeGen;
35
36 namespace {
37
38 /// Holds all the vbtable globals for a given class.
39 struct VBTableGlobals {
40 const VPtrInfoVector *VBTables;
41 SmallVector<llvm::GlobalVariable *, 2> Globals;
42 };
43
44 class MicrosoftCXXABI : public CGCXXABI {
45 public:
MicrosoftCXXABI(CodeGenModule & CGM)46 MicrosoftCXXABI(CodeGenModule &CGM)
47 : CGCXXABI(CGM), BaseClassDescriptorType(nullptr),
48 ClassHierarchyDescriptorType(nullptr),
49 CompleteObjectLocatorType(nullptr), CatchableTypeType(nullptr),
50 ThrowInfoType(nullptr) {}
51
52 bool HasThisReturn(GlobalDecl GD) const override;
53 bool hasMostDerivedReturn(GlobalDecl GD) const override;
54
55 bool classifyReturnType(CGFunctionInfo &FI) const override;
56
57 RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const override;
58
isSRetParameterAfterThis() const59 bool isSRetParameterAfterThis() const override { return true; }
60
isThisCompleteObject(GlobalDecl GD) const61 bool isThisCompleteObject(GlobalDecl GD) const override {
62 // The Microsoft ABI doesn't use separate complete-object vs.
63 // base-object variants of constructors, but it does of destructors.
64 if (isa<CXXDestructorDecl>(GD.getDecl())) {
65 switch (GD.getDtorType()) {
66 case Dtor_Complete:
67 case Dtor_Deleting:
68 return true;
69
70 case Dtor_Base:
71 return false;
72
73 case Dtor_Comdat: llvm_unreachable("emitting dtor comdat as function?");
74 }
75 llvm_unreachable("bad dtor kind");
76 }
77
78 // No other kinds.
79 return false;
80 }
81
getSrcArgforCopyCtor(const CXXConstructorDecl * CD,FunctionArgList & Args) const82 size_t getSrcArgforCopyCtor(const CXXConstructorDecl *CD,
83 FunctionArgList &Args) const override {
84 assert(Args.size() >= 2 &&
85 "expected the arglist to have at least two args!");
86 // The 'most_derived' parameter goes second if the ctor is variadic and
87 // has v-bases.
88 if (CD->getParent()->getNumVBases() > 0 &&
89 CD->getType()->castAs<FunctionProtoType>()->isVariadic())
90 return 2;
91 return 1;
92 }
93
getVBPtrOffsets(const CXXRecordDecl * RD)94 std::vector<CharUnits> getVBPtrOffsets(const CXXRecordDecl *RD) override {
95 std::vector<CharUnits> VBPtrOffsets;
96 const ASTContext &Context = getContext();
97 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
98
99 const VBTableGlobals &VBGlobals = enumerateVBTables(RD);
100 for (const std::unique_ptr<VPtrInfo> &VBT : *VBGlobals.VBTables) {
101 const ASTRecordLayout &SubobjectLayout =
102 Context.getASTRecordLayout(VBT->IntroducingObject);
103 CharUnits Offs = VBT->NonVirtualOffset;
104 Offs += SubobjectLayout.getVBPtrOffset();
105 if (VBT->getVBaseWithVPtr())
106 Offs += Layout.getVBaseClassOffset(VBT->getVBaseWithVPtr());
107 VBPtrOffsets.push_back(Offs);
108 }
109 llvm::array_pod_sort(VBPtrOffsets.begin(), VBPtrOffsets.end());
110 return VBPtrOffsets;
111 }
112
GetPureVirtualCallName()113 StringRef GetPureVirtualCallName() override { return "_purecall"; }
GetDeletedVirtualCallName()114 StringRef GetDeletedVirtualCallName() override { return "_purecall"; }
115
116 void emitVirtualObjectDelete(CodeGenFunction &CGF, const CXXDeleteExpr *DE,
117 Address Ptr, QualType ElementType,
118 const CXXDestructorDecl *Dtor) override;
119
120 void emitRethrow(CodeGenFunction &CGF, bool isNoReturn) override;
121 void emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) override;
122
123 void emitBeginCatch(CodeGenFunction &CGF, const CXXCatchStmt *C) override;
124
125 llvm::GlobalVariable *getMSCompleteObjectLocator(const CXXRecordDecl *RD,
126 const VPtrInfo &Info);
127
128 llvm::Constant *getAddrOfRTTIDescriptor(QualType Ty) override;
129 CatchTypeInfo
130 getAddrOfCXXCatchHandlerType(QualType Ty, QualType CatchHandlerType) override;
131
132 /// MSVC needs an extra flag to indicate a catchall.
getCatchAllTypeInfo()133 CatchTypeInfo getCatchAllTypeInfo() override {
134 return CatchTypeInfo{nullptr, 0x40};
135 }
136
137 bool shouldTypeidBeNullChecked(bool IsDeref, QualType SrcRecordTy) override;
138 void EmitBadTypeidCall(CodeGenFunction &CGF) override;
139 llvm::Value *EmitTypeid(CodeGenFunction &CGF, QualType SrcRecordTy,
140 Address ThisPtr,
141 llvm::Type *StdTypeInfoPtrTy) override;
142
143 bool shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,
144 QualType SrcRecordTy) override;
145
146 llvm::Value *EmitDynamicCastCall(CodeGenFunction &CGF, Address Value,
147 QualType SrcRecordTy, QualType DestTy,
148 QualType DestRecordTy,
149 llvm::BasicBlock *CastEnd) override;
150
151 llvm::Value *EmitDynamicCastToVoid(CodeGenFunction &CGF, Address Value,
152 QualType SrcRecordTy,
153 QualType DestTy) override;
154
155 bool EmitBadCastCall(CodeGenFunction &CGF) override;
canSpeculativelyEmitVTable(const CXXRecordDecl * RD) const156 bool canSpeculativelyEmitVTable(const CXXRecordDecl *RD) const override {
157 return false;
158 }
159
160 llvm::Value *
161 GetVirtualBaseClassOffset(CodeGenFunction &CGF, Address This,
162 const CXXRecordDecl *ClassDecl,
163 const CXXRecordDecl *BaseClassDecl) override;
164
165 llvm::BasicBlock *
166 EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
167 const CXXRecordDecl *RD) override;
168
169 llvm::BasicBlock *
170 EmitDtorCompleteObjectHandler(CodeGenFunction &CGF);
171
172 void initializeHiddenVirtualInheritanceMembers(CodeGenFunction &CGF,
173 const CXXRecordDecl *RD) override;
174
175 void EmitCXXConstructors(const CXXConstructorDecl *D) override;
176
177 // Background on MSVC destructors
178 // ==============================
179 //
180 // Both Itanium and MSVC ABIs have destructor variants. The variant names
181 // roughly correspond in the following way:
182 // Itanium Microsoft
183 // Base -> no name, just ~Class
184 // Complete -> vbase destructor
185 // Deleting -> scalar deleting destructor
186 // vector deleting destructor
187 //
188 // The base and complete destructors are the same as in Itanium, although the
189 // complete destructor does not accept a VTT parameter when there are virtual
190 // bases. A separate mechanism involving vtordisps is used to ensure that
191 // virtual methods of destroyed subobjects are not called.
192 //
193 // The deleting destructors accept an i32 bitfield as a second parameter. Bit
194 // 1 indicates if the memory should be deleted. Bit 2 indicates if the this
195 // pointer points to an array. The scalar deleting destructor assumes that
196 // bit 2 is zero, and therefore does not contain a loop.
197 //
198 // For virtual destructors, only one entry is reserved in the vftable, and it
199 // always points to the vector deleting destructor. The vector deleting
200 // destructor is the most general, so it can be used to destroy objects in
201 // place, delete single heap objects, or delete arrays.
202 //
203 // A TU defining a non-inline destructor is only guaranteed to emit a base
204 // destructor, and all of the other variants are emitted on an as-needed basis
205 // in COMDATs. Because a non-base destructor can be emitted in a TU that
206 // lacks a definition for the destructor, non-base destructors must always
207 // delegate to or alias the base destructor.
208
209 AddedStructorArgs
210 buildStructorSignature(GlobalDecl GD,
211 SmallVectorImpl<CanQualType> &ArgTys) override;
212
213 /// Non-base dtors should be emitted as delegating thunks in this ABI.
useThunkForDtorVariant(const CXXDestructorDecl * Dtor,CXXDtorType DT) const214 bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor,
215 CXXDtorType DT) const override {
216 return DT != Dtor_Base;
217 }
218
219 void setCXXDestructorDLLStorage(llvm::GlobalValue *GV,
220 const CXXDestructorDecl *Dtor,
221 CXXDtorType DT) const override;
222
223 llvm::GlobalValue::LinkageTypes
224 getCXXDestructorLinkage(GVALinkage Linkage, const CXXDestructorDecl *Dtor,
225 CXXDtorType DT) const override;
226
227 void EmitCXXDestructors(const CXXDestructorDecl *D) override;
228
229 const CXXRecordDecl *
getThisArgumentTypeForMethod(const CXXMethodDecl * MD)230 getThisArgumentTypeForMethod(const CXXMethodDecl *MD) override {
231 if (MD->isVirtual() && !isa<CXXDestructorDecl>(MD)) {
232 MethodVFTableLocation ML =
233 CGM.getMicrosoftVTableContext().getMethodVFTableLocation(MD);
234 // The vbases might be ordered differently in the final overrider object
235 // and the complete object, so the "this" argument may sometimes point to
236 // memory that has no particular type (e.g. past the complete object).
237 // In this case, we just use a generic pointer type.
238 // FIXME: might want to have a more precise type in the non-virtual
239 // multiple inheritance case.
240 if (ML.VBase || !ML.VFPtrOffset.isZero())
241 return nullptr;
242 }
243 return MD->getParent();
244 }
245
246 Address
247 adjustThisArgumentForVirtualFunctionCall(CodeGenFunction &CGF, GlobalDecl GD,
248 Address This,
249 bool VirtualCall) override;
250
251 void addImplicitStructorParams(CodeGenFunction &CGF, QualType &ResTy,
252 FunctionArgList &Params) override;
253
254 void EmitInstanceFunctionProlog(CodeGenFunction &CGF) override;
255
256 AddedStructorArgs
257 addImplicitConstructorArgs(CodeGenFunction &CGF, const CXXConstructorDecl *D,
258 CXXCtorType Type, bool ForVirtualBase,
259 bool Delegating, CallArgList &Args) override;
260
261 void EmitDestructorCall(CodeGenFunction &CGF, const CXXDestructorDecl *DD,
262 CXXDtorType Type, bool ForVirtualBase,
263 bool Delegating, Address This,
264 QualType ThisTy) override;
265
266 void emitVTableTypeMetadata(const VPtrInfo &Info, const CXXRecordDecl *RD,
267 llvm::GlobalVariable *VTable);
268
269 void emitVTableDefinitions(CodeGenVTables &CGVT,
270 const CXXRecordDecl *RD) override;
271
272 bool isVirtualOffsetNeededForVTableField(CodeGenFunction &CGF,
273 CodeGenFunction::VPtr Vptr) override;
274
275 /// Don't initialize vptrs if dynamic class
276 /// is marked with with the 'novtable' attribute.
doStructorsInitializeVPtrs(const CXXRecordDecl * VTableClass)277 bool doStructorsInitializeVPtrs(const CXXRecordDecl *VTableClass) override {
278 return !VTableClass->hasAttr<MSNoVTableAttr>();
279 }
280
281 llvm::Constant *
282 getVTableAddressPoint(BaseSubobject Base,
283 const CXXRecordDecl *VTableClass) override;
284
285 llvm::Value *getVTableAddressPointInStructor(
286 CodeGenFunction &CGF, const CXXRecordDecl *VTableClass,
287 BaseSubobject Base, const CXXRecordDecl *NearestVBase) override;
288
289 llvm::Constant *
290 getVTableAddressPointForConstExpr(BaseSubobject Base,
291 const CXXRecordDecl *VTableClass) override;
292
293 llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD,
294 CharUnits VPtrOffset) override;
295
296 CGCallee getVirtualFunctionPointer(CodeGenFunction &CGF, GlobalDecl GD,
297 Address This, llvm::Type *Ty,
298 SourceLocation Loc) override;
299
300 llvm::Value *EmitVirtualDestructorCall(CodeGenFunction &CGF,
301 const CXXDestructorDecl *Dtor,
302 CXXDtorType DtorType, Address This,
303 DeleteOrMemberCallExpr E) override;
304
adjustCallArgsForDestructorThunk(CodeGenFunction & CGF,GlobalDecl GD,CallArgList & CallArgs)305 void adjustCallArgsForDestructorThunk(CodeGenFunction &CGF, GlobalDecl GD,
306 CallArgList &CallArgs) override {
307 assert(GD.getDtorType() == Dtor_Deleting &&
308 "Only deleting destructor thunks are available in this ABI");
309 CallArgs.add(RValue::get(getStructorImplicitParamValue(CGF)),
310 getContext().IntTy);
311 }
312
313 void emitVirtualInheritanceTables(const CXXRecordDecl *RD) override;
314
315 llvm::GlobalVariable *
316 getAddrOfVBTable(const VPtrInfo &VBT, const CXXRecordDecl *RD,
317 llvm::GlobalVariable::LinkageTypes Linkage);
318
319 llvm::GlobalVariable *
getAddrOfVirtualDisplacementMap(const CXXRecordDecl * SrcRD,const CXXRecordDecl * DstRD)320 getAddrOfVirtualDisplacementMap(const CXXRecordDecl *SrcRD,
321 const CXXRecordDecl *DstRD) {
322 SmallString<256> OutName;
323 llvm::raw_svector_ostream Out(OutName);
324 getMangleContext().mangleCXXVirtualDisplacementMap(SrcRD, DstRD, Out);
325 StringRef MangledName = OutName.str();
326
327 if (auto *VDispMap = CGM.getModule().getNamedGlobal(MangledName))
328 return VDispMap;
329
330 MicrosoftVTableContext &VTContext = CGM.getMicrosoftVTableContext();
331 unsigned NumEntries = 1 + SrcRD->getNumVBases();
332 SmallVector<llvm::Constant *, 4> Map(NumEntries,
333 llvm::UndefValue::get(CGM.IntTy));
334 Map[0] = llvm::ConstantInt::get(CGM.IntTy, 0);
335 bool AnyDifferent = false;
336 for (const auto &I : SrcRD->vbases()) {
337 const CXXRecordDecl *VBase = I.getType()->getAsCXXRecordDecl();
338 if (!DstRD->isVirtuallyDerivedFrom(VBase))
339 continue;
340
341 unsigned SrcVBIndex = VTContext.getVBTableIndex(SrcRD, VBase);
342 unsigned DstVBIndex = VTContext.getVBTableIndex(DstRD, VBase);
343 Map[SrcVBIndex] = llvm::ConstantInt::get(CGM.IntTy, DstVBIndex * 4);
344 AnyDifferent |= SrcVBIndex != DstVBIndex;
345 }
346 // This map would be useless, don't use it.
347 if (!AnyDifferent)
348 return nullptr;
349
350 llvm::ArrayType *VDispMapTy = llvm::ArrayType::get(CGM.IntTy, Map.size());
351 llvm::Constant *Init = llvm::ConstantArray::get(VDispMapTy, Map);
352 llvm::GlobalValue::LinkageTypes Linkage =
353 SrcRD->isExternallyVisible() && DstRD->isExternallyVisible()
354 ? llvm::GlobalValue::LinkOnceODRLinkage
355 : llvm::GlobalValue::InternalLinkage;
356 auto *VDispMap = new llvm::GlobalVariable(
357 CGM.getModule(), VDispMapTy, /*isConstant=*/true, Linkage,
358 /*Initializer=*/Init, MangledName);
359 return VDispMap;
360 }
361
362 void emitVBTableDefinition(const VPtrInfo &VBT, const CXXRecordDecl *RD,
363 llvm::GlobalVariable *GV) const;
364
setThunkLinkage(llvm::Function * Thunk,bool ForVTable,GlobalDecl GD,bool ReturnAdjustment)365 void setThunkLinkage(llvm::Function *Thunk, bool ForVTable,
366 GlobalDecl GD, bool ReturnAdjustment) override {
367 GVALinkage Linkage =
368 getContext().GetGVALinkageForFunction(cast<FunctionDecl>(GD.getDecl()));
369
370 if (Linkage == GVA_Internal)
371 Thunk->setLinkage(llvm::GlobalValue::InternalLinkage);
372 else if (ReturnAdjustment)
373 Thunk->setLinkage(llvm::GlobalValue::WeakODRLinkage);
374 else
375 Thunk->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage);
376 }
377
exportThunk()378 bool exportThunk() override { return false; }
379
380 llvm::Value *performThisAdjustment(CodeGenFunction &CGF, Address This,
381 const ThisAdjustment &TA) override;
382
383 llvm::Value *performReturnAdjustment(CodeGenFunction &CGF, Address Ret,
384 const ReturnAdjustment &RA) override;
385
386 void EmitThreadLocalInitFuncs(
387 CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals,
388 ArrayRef<llvm::Function *> CXXThreadLocalInits,
389 ArrayRef<const VarDecl *> CXXThreadLocalInitVars) override;
390
usesThreadWrapperFunction(const VarDecl * VD) const391 bool usesThreadWrapperFunction(const VarDecl *VD) const override {
392 return false;
393 }
394 LValue EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF, const VarDecl *VD,
395 QualType LValType) override;
396
397 void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
398 llvm::GlobalVariable *DeclPtr,
399 bool PerformInit) override;
400 void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,
401 llvm::FunctionCallee Dtor,
402 llvm::Constant *Addr) override;
403
404 // ==== Notes on array cookies =========
405 //
406 // MSVC seems to only use cookies when the class has a destructor; a
407 // two-argument usual array deallocation function isn't sufficient.
408 //
409 // For example, this code prints "100" and "1":
410 // struct A {
411 // char x;
412 // void *operator new[](size_t sz) {
413 // printf("%u\n", sz);
414 // return malloc(sz);
415 // }
416 // void operator delete[](void *p, size_t sz) {
417 // printf("%u\n", sz);
418 // free(p);
419 // }
420 // };
421 // int main() {
422 // A *p = new A[100];
423 // delete[] p;
424 // }
425 // Whereas it prints "104" and "104" if you give A a destructor.
426
427 bool requiresArrayCookie(const CXXDeleteExpr *expr,
428 QualType elementType) override;
429 bool requiresArrayCookie(const CXXNewExpr *expr) override;
430 CharUnits getArrayCookieSizeImpl(QualType type) override;
431 Address InitializeArrayCookie(CodeGenFunction &CGF,
432 Address NewPtr,
433 llvm::Value *NumElements,
434 const CXXNewExpr *expr,
435 QualType ElementType) override;
436 llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF,
437 Address allocPtr,
438 CharUnits cookieSize) override;
439
440 friend struct MSRTTIBuilder;
441
isImageRelative() const442 bool isImageRelative() const {
443 return CGM.getTarget().getPointerWidth(/*AddrSpace=*/0) == 64;
444 }
445
446 // 5 routines for constructing the llvm types for MS RTTI structs.
getTypeDescriptorType(StringRef TypeInfoString)447 llvm::StructType *getTypeDescriptorType(StringRef TypeInfoString) {
448 llvm::SmallString<32> TDTypeName("rtti.TypeDescriptor");
449 TDTypeName += llvm::utostr(TypeInfoString.size());
450 llvm::StructType *&TypeDescriptorType =
451 TypeDescriptorTypeMap[TypeInfoString.size()];
452 if (TypeDescriptorType)
453 return TypeDescriptorType;
454 llvm::Type *FieldTypes[] = {
455 CGM.Int8PtrPtrTy,
456 CGM.Int8PtrTy,
457 llvm::ArrayType::get(CGM.Int8Ty, TypeInfoString.size() + 1)};
458 TypeDescriptorType =
459 llvm::StructType::create(CGM.getLLVMContext(), FieldTypes, TDTypeName);
460 return TypeDescriptorType;
461 }
462
getImageRelativeType(llvm::Type * PtrType)463 llvm::Type *getImageRelativeType(llvm::Type *PtrType) {
464 if (!isImageRelative())
465 return PtrType;
466 return CGM.IntTy;
467 }
468
getBaseClassDescriptorType()469 llvm::StructType *getBaseClassDescriptorType() {
470 if (BaseClassDescriptorType)
471 return BaseClassDescriptorType;
472 llvm::Type *FieldTypes[] = {
473 getImageRelativeType(CGM.Int8PtrTy),
474 CGM.IntTy,
475 CGM.IntTy,
476 CGM.IntTy,
477 CGM.IntTy,
478 CGM.IntTy,
479 getImageRelativeType(getClassHierarchyDescriptorType()->getPointerTo()),
480 };
481 BaseClassDescriptorType = llvm::StructType::create(
482 CGM.getLLVMContext(), FieldTypes, "rtti.BaseClassDescriptor");
483 return BaseClassDescriptorType;
484 }
485
getClassHierarchyDescriptorType()486 llvm::StructType *getClassHierarchyDescriptorType() {
487 if (ClassHierarchyDescriptorType)
488 return ClassHierarchyDescriptorType;
489 // Forward-declare RTTIClassHierarchyDescriptor to break a cycle.
490 ClassHierarchyDescriptorType = llvm::StructType::create(
491 CGM.getLLVMContext(), "rtti.ClassHierarchyDescriptor");
492 llvm::Type *FieldTypes[] = {
493 CGM.IntTy,
494 CGM.IntTy,
495 CGM.IntTy,
496 getImageRelativeType(
497 getBaseClassDescriptorType()->getPointerTo()->getPointerTo()),
498 };
499 ClassHierarchyDescriptorType->setBody(FieldTypes);
500 return ClassHierarchyDescriptorType;
501 }
502
getCompleteObjectLocatorType()503 llvm::StructType *getCompleteObjectLocatorType() {
504 if (CompleteObjectLocatorType)
505 return CompleteObjectLocatorType;
506 CompleteObjectLocatorType = llvm::StructType::create(
507 CGM.getLLVMContext(), "rtti.CompleteObjectLocator");
508 llvm::Type *FieldTypes[] = {
509 CGM.IntTy,
510 CGM.IntTy,
511 CGM.IntTy,
512 getImageRelativeType(CGM.Int8PtrTy),
513 getImageRelativeType(getClassHierarchyDescriptorType()->getPointerTo()),
514 getImageRelativeType(CompleteObjectLocatorType),
515 };
516 llvm::ArrayRef<llvm::Type *> FieldTypesRef(FieldTypes);
517 if (!isImageRelative())
518 FieldTypesRef = FieldTypesRef.drop_back();
519 CompleteObjectLocatorType->setBody(FieldTypesRef);
520 return CompleteObjectLocatorType;
521 }
522
getImageBase()523 llvm::GlobalVariable *getImageBase() {
524 StringRef Name = "__ImageBase";
525 if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(Name))
526 return GV;
527
528 auto *GV = new llvm::GlobalVariable(CGM.getModule(), CGM.Int8Ty,
529 /*isConstant=*/true,
530 llvm::GlobalValue::ExternalLinkage,
531 /*Initializer=*/nullptr, Name);
532 CGM.setDSOLocal(GV);
533 return GV;
534 }
535
getImageRelativeConstant(llvm::Constant * PtrVal)536 llvm::Constant *getImageRelativeConstant(llvm::Constant *PtrVal) {
537 if (!isImageRelative())
538 return PtrVal;
539
540 if (PtrVal->isNullValue())
541 return llvm::Constant::getNullValue(CGM.IntTy);
542
543 llvm::Constant *ImageBaseAsInt =
544 llvm::ConstantExpr::getPtrToInt(getImageBase(), CGM.IntPtrTy);
545 llvm::Constant *PtrValAsInt =
546 llvm::ConstantExpr::getPtrToInt(PtrVal, CGM.IntPtrTy);
547 llvm::Constant *Diff =
548 llvm::ConstantExpr::getSub(PtrValAsInt, ImageBaseAsInt,
549 /*HasNUW=*/true, /*HasNSW=*/true);
550 return llvm::ConstantExpr::getTrunc(Diff, CGM.IntTy);
551 }
552
553 private:
getMangleContext()554 MicrosoftMangleContext &getMangleContext() {
555 return cast<MicrosoftMangleContext>(CodeGen::CGCXXABI::getMangleContext());
556 }
557
getZeroInt()558 llvm::Constant *getZeroInt() {
559 return llvm::ConstantInt::get(CGM.IntTy, 0);
560 }
561
getAllOnesInt()562 llvm::Constant *getAllOnesInt() {
563 return llvm::Constant::getAllOnesValue(CGM.IntTy);
564 }
565
566 CharUnits getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) override;
567
568 void
569 GetNullMemberPointerFields(const MemberPointerType *MPT,
570 llvm::SmallVectorImpl<llvm::Constant *> &fields);
571
572 /// Shared code for virtual base adjustment. Returns the offset from
573 /// the vbptr to the virtual base. Optionally returns the address of the
574 /// vbptr itself.
575 llvm::Value *GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,
576 Address Base,
577 llvm::Value *VBPtrOffset,
578 llvm::Value *VBTableOffset,
579 llvm::Value **VBPtr = nullptr);
580
GetVBaseOffsetFromVBPtr(CodeGenFunction & CGF,Address Base,int32_t VBPtrOffset,int32_t VBTableOffset,llvm::Value ** VBPtr=nullptr)581 llvm::Value *GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,
582 Address Base,
583 int32_t VBPtrOffset,
584 int32_t VBTableOffset,
585 llvm::Value **VBPtr = nullptr) {
586 assert(VBTableOffset % 4 == 0 && "should be byte offset into table of i32s");
587 llvm::Value *VBPOffset = llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset),
588 *VBTOffset = llvm::ConstantInt::get(CGM.IntTy, VBTableOffset);
589 return GetVBaseOffsetFromVBPtr(CGF, Base, VBPOffset, VBTOffset, VBPtr);
590 }
591
592 std::tuple<Address, llvm::Value *, const CXXRecordDecl *>
593 performBaseAdjustment(CodeGenFunction &CGF, Address Value,
594 QualType SrcRecordTy);
595
596 /// Performs a full virtual base adjustment. Used to dereference
597 /// pointers to members of virtual bases.
598 llvm::Value *AdjustVirtualBase(CodeGenFunction &CGF, const Expr *E,
599 const CXXRecordDecl *RD, Address Base,
600 llvm::Value *VirtualBaseAdjustmentOffset,
601 llvm::Value *VBPtrOffset /* optional */);
602
603 /// Emits a full member pointer with the fields common to data and
604 /// function member pointers.
605 llvm::Constant *EmitFullMemberPointer(llvm::Constant *FirstField,
606 bool IsMemberFunction,
607 const CXXRecordDecl *RD,
608 CharUnits NonVirtualBaseAdjustment,
609 unsigned VBTableIndex);
610
611 bool MemberPointerConstantIsNull(const MemberPointerType *MPT,
612 llvm::Constant *MP);
613
614 /// - Initialize all vbptrs of 'this' with RD as the complete type.
615 void EmitVBPtrStores(CodeGenFunction &CGF, const CXXRecordDecl *RD);
616
617 /// Caching wrapper around VBTableBuilder::enumerateVBTables().
618 const VBTableGlobals &enumerateVBTables(const CXXRecordDecl *RD);
619
620 /// Generate a thunk for calling a virtual member function MD.
621 llvm::Function *EmitVirtualMemPtrThunk(const CXXMethodDecl *MD,
622 const MethodVFTableLocation &ML);
623
624 llvm::Constant *EmitMemberDataPointer(const CXXRecordDecl *RD,
625 CharUnits offset);
626
627 public:
628 llvm::Type *ConvertMemberPointerType(const MemberPointerType *MPT) override;
629
630 bool isZeroInitializable(const MemberPointerType *MPT) override;
631
isMemberPointerConvertible(const MemberPointerType * MPT) const632 bool isMemberPointerConvertible(const MemberPointerType *MPT) const override {
633 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
634 return RD->hasAttr<MSInheritanceAttr>();
635 }
636
637 llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT) override;
638
639 llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,
640 CharUnits offset) override;
641 llvm::Constant *EmitMemberFunctionPointer(const CXXMethodDecl *MD) override;
642 llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT) override;
643
644 llvm::Value *EmitMemberPointerComparison(CodeGenFunction &CGF,
645 llvm::Value *L,
646 llvm::Value *R,
647 const MemberPointerType *MPT,
648 bool Inequality) override;
649
650 llvm::Value *EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
651 llvm::Value *MemPtr,
652 const MemberPointerType *MPT) override;
653
654 llvm::Value *
655 EmitMemberDataPointerAddress(CodeGenFunction &CGF, const Expr *E,
656 Address Base, llvm::Value *MemPtr,
657 const MemberPointerType *MPT) override;
658
659 llvm::Value *EmitNonNullMemberPointerConversion(
660 const MemberPointerType *SrcTy, const MemberPointerType *DstTy,
661 CastKind CK, CastExpr::path_const_iterator PathBegin,
662 CastExpr::path_const_iterator PathEnd, llvm::Value *Src,
663 CGBuilderTy &Builder);
664
665 llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,
666 const CastExpr *E,
667 llvm::Value *Src) override;
668
669 llvm::Constant *EmitMemberPointerConversion(const CastExpr *E,
670 llvm::Constant *Src) override;
671
672 llvm::Constant *EmitMemberPointerConversion(
673 const MemberPointerType *SrcTy, const MemberPointerType *DstTy,
674 CastKind CK, CastExpr::path_const_iterator PathBegin,
675 CastExpr::path_const_iterator PathEnd, llvm::Constant *Src);
676
677 CGCallee
678 EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, const Expr *E,
679 Address This, llvm::Value *&ThisPtrForCall,
680 llvm::Value *MemPtr,
681 const MemberPointerType *MPT) override;
682
683 void emitCXXStructor(GlobalDecl GD) override;
684
getCatchableTypeType()685 llvm::StructType *getCatchableTypeType() {
686 if (CatchableTypeType)
687 return CatchableTypeType;
688 llvm::Type *FieldTypes[] = {
689 CGM.IntTy, // Flags
690 getImageRelativeType(CGM.Int8PtrTy), // TypeDescriptor
691 CGM.IntTy, // NonVirtualAdjustment
692 CGM.IntTy, // OffsetToVBPtr
693 CGM.IntTy, // VBTableIndex
694 CGM.IntTy, // Size
695 getImageRelativeType(CGM.Int8PtrTy) // CopyCtor
696 };
697 CatchableTypeType = llvm::StructType::create(
698 CGM.getLLVMContext(), FieldTypes, "eh.CatchableType");
699 return CatchableTypeType;
700 }
701
getCatchableTypeArrayType(uint32_t NumEntries)702 llvm::StructType *getCatchableTypeArrayType(uint32_t NumEntries) {
703 llvm::StructType *&CatchableTypeArrayType =
704 CatchableTypeArrayTypeMap[NumEntries];
705 if (CatchableTypeArrayType)
706 return CatchableTypeArrayType;
707
708 llvm::SmallString<23> CTATypeName("eh.CatchableTypeArray.");
709 CTATypeName += llvm::utostr(NumEntries);
710 llvm::Type *CTType =
711 getImageRelativeType(getCatchableTypeType()->getPointerTo());
712 llvm::Type *FieldTypes[] = {
713 CGM.IntTy, // NumEntries
714 llvm::ArrayType::get(CTType, NumEntries) // CatchableTypes
715 };
716 CatchableTypeArrayType =
717 llvm::StructType::create(CGM.getLLVMContext(), FieldTypes, CTATypeName);
718 return CatchableTypeArrayType;
719 }
720
getThrowInfoType()721 llvm::StructType *getThrowInfoType() {
722 if (ThrowInfoType)
723 return ThrowInfoType;
724 llvm::Type *FieldTypes[] = {
725 CGM.IntTy, // Flags
726 getImageRelativeType(CGM.Int8PtrTy), // CleanupFn
727 getImageRelativeType(CGM.Int8PtrTy), // ForwardCompat
728 getImageRelativeType(CGM.Int8PtrTy) // CatchableTypeArray
729 };
730 ThrowInfoType = llvm::StructType::create(CGM.getLLVMContext(), FieldTypes,
731 "eh.ThrowInfo");
732 return ThrowInfoType;
733 }
734
getThrowFn()735 llvm::FunctionCallee getThrowFn() {
736 // _CxxThrowException is passed an exception object and a ThrowInfo object
737 // which describes the exception.
738 llvm::Type *Args[] = {CGM.Int8PtrTy, getThrowInfoType()->getPointerTo()};
739 llvm::FunctionType *FTy =
740 llvm::FunctionType::get(CGM.VoidTy, Args, /*isVarArg=*/false);
741 llvm::FunctionCallee Throw =
742 CGM.CreateRuntimeFunction(FTy, "_CxxThrowException");
743 // _CxxThrowException is stdcall on 32-bit x86 platforms.
744 if (CGM.getTarget().getTriple().getArch() == llvm::Triple::x86) {
745 if (auto *Fn = dyn_cast<llvm::Function>(Throw.getCallee()))
746 Fn->setCallingConv(llvm::CallingConv::X86_StdCall);
747 }
748 return Throw;
749 }
750
751 llvm::Function *getAddrOfCXXCtorClosure(const CXXConstructorDecl *CD,
752 CXXCtorType CT);
753
754 llvm::Constant *getCatchableType(QualType T,
755 uint32_t NVOffset = 0,
756 int32_t VBPtrOffset = -1,
757 uint32_t VBIndex = 0);
758
759 llvm::GlobalVariable *getCatchableTypeArray(QualType T);
760
761 llvm::GlobalVariable *getThrowInfo(QualType T) override;
762
763 std::pair<llvm::Value *, const CXXRecordDecl *>
764 LoadVTablePtr(CodeGenFunction &CGF, Address This,
765 const CXXRecordDecl *RD) override;
766
767 private:
768 typedef std::pair<const CXXRecordDecl *, CharUnits> VFTableIdTy;
769 typedef llvm::DenseMap<VFTableIdTy, llvm::GlobalVariable *> VTablesMapTy;
770 typedef llvm::DenseMap<VFTableIdTy, llvm::GlobalValue *> VFTablesMapTy;
771 /// All the vftables that have been referenced.
772 VFTablesMapTy VFTablesMap;
773 VTablesMapTy VTablesMap;
774
775 /// This set holds the record decls we've deferred vtable emission for.
776 llvm::SmallPtrSet<const CXXRecordDecl *, 4> DeferredVFTables;
777
778
779 /// All the vbtables which have been referenced.
780 llvm::DenseMap<const CXXRecordDecl *, VBTableGlobals> VBTablesMap;
781
782 /// Info on the global variable used to guard initialization of static locals.
783 /// The BitIndex field is only used for externally invisible declarations.
784 struct GuardInfo {
GuardInfo__anon4d9609fc0111::MicrosoftCXXABI::GuardInfo785 GuardInfo() : Guard(nullptr), BitIndex(0) {}
786 llvm::GlobalVariable *Guard;
787 unsigned BitIndex;
788 };
789
790 /// Map from DeclContext to the current guard variable. We assume that the
791 /// AST is visited in source code order.
792 llvm::DenseMap<const DeclContext *, GuardInfo> GuardVariableMap;
793 llvm::DenseMap<const DeclContext *, GuardInfo> ThreadLocalGuardVariableMap;
794 llvm::DenseMap<const DeclContext *, unsigned> ThreadSafeGuardNumMap;
795
796 llvm::DenseMap<size_t, llvm::StructType *> TypeDescriptorTypeMap;
797 llvm::StructType *BaseClassDescriptorType;
798 llvm::StructType *ClassHierarchyDescriptorType;
799 llvm::StructType *CompleteObjectLocatorType;
800
801 llvm::DenseMap<QualType, llvm::GlobalVariable *> CatchableTypeArrays;
802
803 llvm::StructType *CatchableTypeType;
804 llvm::DenseMap<uint32_t, llvm::StructType *> CatchableTypeArrayTypeMap;
805 llvm::StructType *ThrowInfoType;
806 };
807
808 }
809
810 CGCXXABI::RecordArgABI
getRecordArgABI(const CXXRecordDecl * RD) const811 MicrosoftCXXABI::getRecordArgABI(const CXXRecordDecl *RD) const {
812 switch (CGM.getTarget().getTriple().getArch()) {
813 default:
814 // FIXME: Implement for other architectures.
815 return RAA_Default;
816
817 case llvm::Triple::thumb:
818 // Use the simple Itanium rules for now.
819 // FIXME: This is incompatible with MSVC for arguments with a dtor and no
820 // copy ctor.
821 return !RD->canPassInRegisters() ? RAA_Indirect : RAA_Default;
822
823 case llvm::Triple::x86:
824 // All record arguments are passed in memory on x86. Decide whether to
825 // construct the object directly in argument memory, or to construct the
826 // argument elsewhere and copy the bytes during the call.
827
828 // If C++ prohibits us from making a copy, construct the arguments directly
829 // into argument memory.
830 if (!RD->canPassInRegisters())
831 return RAA_DirectInMemory;
832
833 // Otherwise, construct the argument into a temporary and copy the bytes
834 // into the outgoing argument memory.
835 return RAA_Default;
836
837 case llvm::Triple::x86_64:
838 case llvm::Triple::aarch64:
839 return !RD->canPassInRegisters() ? RAA_Indirect : RAA_Default;
840 }
841
842 llvm_unreachable("invalid enum");
843 }
844
emitVirtualObjectDelete(CodeGenFunction & CGF,const CXXDeleteExpr * DE,Address Ptr,QualType ElementType,const CXXDestructorDecl * Dtor)845 void MicrosoftCXXABI::emitVirtualObjectDelete(CodeGenFunction &CGF,
846 const CXXDeleteExpr *DE,
847 Address Ptr,
848 QualType ElementType,
849 const CXXDestructorDecl *Dtor) {
850 // FIXME: Provide a source location here even though there's no
851 // CXXMemberCallExpr for dtor call.
852 bool UseGlobalDelete = DE->isGlobalDelete();
853 CXXDtorType DtorType = UseGlobalDelete ? Dtor_Complete : Dtor_Deleting;
854 llvm::Value *MDThis = EmitVirtualDestructorCall(CGF, Dtor, DtorType, Ptr, DE);
855 if (UseGlobalDelete)
856 CGF.EmitDeleteCall(DE->getOperatorDelete(), MDThis, ElementType);
857 }
858
emitRethrow(CodeGenFunction & CGF,bool isNoReturn)859 void MicrosoftCXXABI::emitRethrow(CodeGenFunction &CGF, bool isNoReturn) {
860 llvm::Value *Args[] = {
861 llvm::ConstantPointerNull::get(CGM.Int8PtrTy),
862 llvm::ConstantPointerNull::get(getThrowInfoType()->getPointerTo())};
863 llvm::FunctionCallee Fn = getThrowFn();
864 if (isNoReturn)
865 CGF.EmitNoreturnRuntimeCallOrInvoke(Fn, Args);
866 else
867 CGF.EmitRuntimeCallOrInvoke(Fn, Args);
868 }
869
emitBeginCatch(CodeGenFunction & CGF,const CXXCatchStmt * S)870 void MicrosoftCXXABI::emitBeginCatch(CodeGenFunction &CGF,
871 const CXXCatchStmt *S) {
872 // In the MS ABI, the runtime handles the copy, and the catch handler is
873 // responsible for destruction.
874 VarDecl *CatchParam = S->getExceptionDecl();
875 llvm::BasicBlock *CatchPadBB = CGF.Builder.GetInsertBlock();
876 llvm::CatchPadInst *CPI =
877 cast<llvm::CatchPadInst>(CatchPadBB->getFirstNonPHI());
878 CGF.CurrentFuncletPad = CPI;
879
880 // If this is a catch-all or the catch parameter is unnamed, we don't need to
881 // emit an alloca to the object.
882 if (!CatchParam || !CatchParam->getDeclName()) {
883 CGF.EHStack.pushCleanup<CatchRetScope>(NormalCleanup, CPI);
884 return;
885 }
886
887 CodeGenFunction::AutoVarEmission var = CGF.EmitAutoVarAlloca(*CatchParam);
888 CPI->setArgOperand(2, var.getObjectAddress(CGF).getPointer());
889 CGF.EHStack.pushCleanup<CatchRetScope>(NormalCleanup, CPI);
890 CGF.EmitAutoVarCleanups(var);
891 }
892
893 /// We need to perform a generic polymorphic operation (like a typeid
894 /// or a cast), which requires an object with a vfptr. Adjust the
895 /// address to point to an object with a vfptr.
896 std::tuple<Address, llvm::Value *, const CXXRecordDecl *>
performBaseAdjustment(CodeGenFunction & CGF,Address Value,QualType SrcRecordTy)897 MicrosoftCXXABI::performBaseAdjustment(CodeGenFunction &CGF, Address Value,
898 QualType SrcRecordTy) {
899 Value = CGF.Builder.CreateBitCast(Value, CGF.Int8PtrTy);
900 const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();
901 const ASTContext &Context = getContext();
902
903 // If the class itself has a vfptr, great. This check implicitly
904 // covers non-virtual base subobjects: a class with its own virtual
905 // functions would be a candidate to be a primary base.
906 if (Context.getASTRecordLayout(SrcDecl).hasExtendableVFPtr())
907 return std::make_tuple(Value, llvm::ConstantInt::get(CGF.Int32Ty, 0),
908 SrcDecl);
909
910 // Okay, one of the vbases must have a vfptr, or else this isn't
911 // actually a polymorphic class.
912 const CXXRecordDecl *PolymorphicBase = nullptr;
913 for (auto &Base : SrcDecl->vbases()) {
914 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
915 if (Context.getASTRecordLayout(BaseDecl).hasExtendableVFPtr()) {
916 PolymorphicBase = BaseDecl;
917 break;
918 }
919 }
920 assert(PolymorphicBase && "polymorphic class has no apparent vfptr?");
921
922 llvm::Value *Offset =
923 GetVirtualBaseClassOffset(CGF, Value, SrcDecl, PolymorphicBase);
924 llvm::Value *Ptr = CGF.Builder.CreateInBoundsGEP(Value.getPointer(), Offset);
925 CharUnits VBaseAlign =
926 CGF.CGM.getVBaseAlignment(Value.getAlignment(), SrcDecl, PolymorphicBase);
927 return std::make_tuple(Address(Ptr, VBaseAlign), Offset, PolymorphicBase);
928 }
929
shouldTypeidBeNullChecked(bool IsDeref,QualType SrcRecordTy)930 bool MicrosoftCXXABI::shouldTypeidBeNullChecked(bool IsDeref,
931 QualType SrcRecordTy) {
932 const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();
933 return IsDeref &&
934 !getContext().getASTRecordLayout(SrcDecl).hasExtendableVFPtr();
935 }
936
emitRTtypeidCall(CodeGenFunction & CGF,llvm::Value * Argument)937 static llvm::CallBase *emitRTtypeidCall(CodeGenFunction &CGF,
938 llvm::Value *Argument) {
939 llvm::Type *ArgTypes[] = {CGF.Int8PtrTy};
940 llvm::FunctionType *FTy =
941 llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false);
942 llvm::Value *Args[] = {Argument};
943 llvm::FunctionCallee Fn = CGF.CGM.CreateRuntimeFunction(FTy, "__RTtypeid");
944 return CGF.EmitRuntimeCallOrInvoke(Fn, Args);
945 }
946
EmitBadTypeidCall(CodeGenFunction & CGF)947 void MicrosoftCXXABI::EmitBadTypeidCall(CodeGenFunction &CGF) {
948 llvm::CallBase *Call =
949 emitRTtypeidCall(CGF, llvm::Constant::getNullValue(CGM.VoidPtrTy));
950 Call->setDoesNotReturn();
951 CGF.Builder.CreateUnreachable();
952 }
953
EmitTypeid(CodeGenFunction & CGF,QualType SrcRecordTy,Address ThisPtr,llvm::Type * StdTypeInfoPtrTy)954 llvm::Value *MicrosoftCXXABI::EmitTypeid(CodeGenFunction &CGF,
955 QualType SrcRecordTy,
956 Address ThisPtr,
957 llvm::Type *StdTypeInfoPtrTy) {
958 std::tie(ThisPtr, std::ignore, std::ignore) =
959 performBaseAdjustment(CGF, ThisPtr, SrcRecordTy);
960 llvm::CallBase *Typeid = emitRTtypeidCall(CGF, ThisPtr.getPointer());
961 return CGF.Builder.CreateBitCast(Typeid, StdTypeInfoPtrTy);
962 }
963
shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,QualType SrcRecordTy)964 bool MicrosoftCXXABI::shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,
965 QualType SrcRecordTy) {
966 const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();
967 return SrcIsPtr &&
968 !getContext().getASTRecordLayout(SrcDecl).hasExtendableVFPtr();
969 }
970
EmitDynamicCastCall(CodeGenFunction & CGF,Address This,QualType SrcRecordTy,QualType DestTy,QualType DestRecordTy,llvm::BasicBlock * CastEnd)971 llvm::Value *MicrosoftCXXABI::EmitDynamicCastCall(
972 CodeGenFunction &CGF, Address This, QualType SrcRecordTy,
973 QualType DestTy, QualType DestRecordTy, llvm::BasicBlock *CastEnd) {
974 llvm::Type *DestLTy = CGF.ConvertType(DestTy);
975
976 llvm::Value *SrcRTTI =
977 CGF.CGM.GetAddrOfRTTIDescriptor(SrcRecordTy.getUnqualifiedType());
978 llvm::Value *DestRTTI =
979 CGF.CGM.GetAddrOfRTTIDescriptor(DestRecordTy.getUnqualifiedType());
980
981 llvm::Value *Offset;
982 std::tie(This, Offset, std::ignore) =
983 performBaseAdjustment(CGF, This, SrcRecordTy);
984 llvm::Value *ThisPtr = This.getPointer();
985 Offset = CGF.Builder.CreateTrunc(Offset, CGF.Int32Ty);
986
987 // PVOID __RTDynamicCast(
988 // PVOID inptr,
989 // LONG VfDelta,
990 // PVOID SrcType,
991 // PVOID TargetType,
992 // BOOL isReference)
993 llvm::Type *ArgTypes[] = {CGF.Int8PtrTy, CGF.Int32Ty, CGF.Int8PtrTy,
994 CGF.Int8PtrTy, CGF.Int32Ty};
995 llvm::FunctionCallee Function = CGF.CGM.CreateRuntimeFunction(
996 llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false),
997 "__RTDynamicCast");
998 llvm::Value *Args[] = {
999 ThisPtr, Offset, SrcRTTI, DestRTTI,
1000 llvm::ConstantInt::get(CGF.Int32Ty, DestTy->isReferenceType())};
1001 ThisPtr = CGF.EmitRuntimeCallOrInvoke(Function, Args);
1002 return CGF.Builder.CreateBitCast(ThisPtr, DestLTy);
1003 }
1004
1005 llvm::Value *
EmitDynamicCastToVoid(CodeGenFunction & CGF,Address Value,QualType SrcRecordTy,QualType DestTy)1006 MicrosoftCXXABI::EmitDynamicCastToVoid(CodeGenFunction &CGF, Address Value,
1007 QualType SrcRecordTy,
1008 QualType DestTy) {
1009 std::tie(Value, std::ignore, std::ignore) =
1010 performBaseAdjustment(CGF, Value, SrcRecordTy);
1011
1012 // PVOID __RTCastToVoid(
1013 // PVOID inptr)
1014 llvm::Type *ArgTypes[] = {CGF.Int8PtrTy};
1015 llvm::FunctionCallee Function = CGF.CGM.CreateRuntimeFunction(
1016 llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false),
1017 "__RTCastToVoid");
1018 llvm::Value *Args[] = {Value.getPointer()};
1019 return CGF.EmitRuntimeCall(Function, Args);
1020 }
1021
EmitBadCastCall(CodeGenFunction & CGF)1022 bool MicrosoftCXXABI::EmitBadCastCall(CodeGenFunction &CGF) {
1023 return false;
1024 }
1025
GetVirtualBaseClassOffset(CodeGenFunction & CGF,Address This,const CXXRecordDecl * ClassDecl,const CXXRecordDecl * BaseClassDecl)1026 llvm::Value *MicrosoftCXXABI::GetVirtualBaseClassOffset(
1027 CodeGenFunction &CGF, Address This, const CXXRecordDecl *ClassDecl,
1028 const CXXRecordDecl *BaseClassDecl) {
1029 const ASTContext &Context = getContext();
1030 int64_t VBPtrChars =
1031 Context.getASTRecordLayout(ClassDecl).getVBPtrOffset().getQuantity();
1032 llvm::Value *VBPtrOffset = llvm::ConstantInt::get(CGM.PtrDiffTy, VBPtrChars);
1033 CharUnits IntSize = Context.getTypeSizeInChars(Context.IntTy);
1034 CharUnits VBTableChars =
1035 IntSize *
1036 CGM.getMicrosoftVTableContext().getVBTableIndex(ClassDecl, BaseClassDecl);
1037 llvm::Value *VBTableOffset =
1038 llvm::ConstantInt::get(CGM.IntTy, VBTableChars.getQuantity());
1039
1040 llvm::Value *VBPtrToNewBase =
1041 GetVBaseOffsetFromVBPtr(CGF, This, VBPtrOffset, VBTableOffset);
1042 VBPtrToNewBase =
1043 CGF.Builder.CreateSExtOrBitCast(VBPtrToNewBase, CGM.PtrDiffTy);
1044 return CGF.Builder.CreateNSWAdd(VBPtrOffset, VBPtrToNewBase);
1045 }
1046
HasThisReturn(GlobalDecl GD) const1047 bool MicrosoftCXXABI::HasThisReturn(GlobalDecl GD) const {
1048 return isa<CXXConstructorDecl>(GD.getDecl());
1049 }
1050
isDeletingDtor(GlobalDecl GD)1051 static bool isDeletingDtor(GlobalDecl GD) {
1052 return isa<CXXDestructorDecl>(GD.getDecl()) &&
1053 GD.getDtorType() == Dtor_Deleting;
1054 }
1055
hasMostDerivedReturn(GlobalDecl GD) const1056 bool MicrosoftCXXABI::hasMostDerivedReturn(GlobalDecl GD) const {
1057 return isDeletingDtor(GD);
1058 }
1059
IsSizeGreaterThan128(const CXXRecordDecl * RD)1060 static bool IsSizeGreaterThan128(const CXXRecordDecl *RD) {
1061 return RD->getASTContext().getTypeSize(RD->getTypeForDecl()) > 128;
1062 }
1063
hasMicrosoftABIRestrictions(const CXXRecordDecl * RD)1064 static bool hasMicrosoftABIRestrictions(const CXXRecordDecl *RD) {
1065 // For AArch64, we use the C++14 definition of an aggregate, so we also
1066 // check for:
1067 // No private or protected non static data members.
1068 // No base classes
1069 // No virtual functions
1070 // Additionally, we need to ensure that there is a trivial copy assignment
1071 // operator, a trivial destructor and no user-provided constructors.
1072 if (RD->hasProtectedFields() || RD->hasPrivateFields())
1073 return true;
1074 if (RD->getNumBases() > 0)
1075 return true;
1076 if (RD->isPolymorphic())
1077 return true;
1078 if (RD->hasNonTrivialCopyAssignment())
1079 return true;
1080 for (const CXXConstructorDecl *Ctor : RD->ctors())
1081 if (Ctor->isUserProvided())
1082 return true;
1083 if (RD->hasNonTrivialDestructor())
1084 return true;
1085 return false;
1086 }
1087
classifyReturnType(CGFunctionInfo & FI) const1088 bool MicrosoftCXXABI::classifyReturnType(CGFunctionInfo &FI) const {
1089 const CXXRecordDecl *RD = FI.getReturnType()->getAsCXXRecordDecl();
1090 if (!RD)
1091 return false;
1092
1093 bool isAArch64 = CGM.getTarget().getTriple().isAArch64();
1094 bool isSimple = !isAArch64 || !hasMicrosoftABIRestrictions(RD);
1095 bool isIndirectReturn =
1096 isAArch64 ? (!RD->canPassInRegisters() ||
1097 IsSizeGreaterThan128(RD))
1098 : !RD->isPOD();
1099 bool isInstanceMethod = FI.isInstanceMethod();
1100
1101 if (isIndirectReturn || !isSimple || isInstanceMethod) {
1102 CharUnits Align = CGM.getContext().getTypeAlignInChars(FI.getReturnType());
1103 FI.getReturnInfo() = ABIArgInfo::getIndirect(Align, /*ByVal=*/false);
1104 FI.getReturnInfo().setSRetAfterThis(isInstanceMethod);
1105
1106 FI.getReturnInfo().setInReg(isAArch64 &&
1107 !(isSimple && IsSizeGreaterThan128(RD)));
1108
1109 return true;
1110 }
1111
1112 // Otherwise, use the C ABI rules.
1113 return false;
1114 }
1115
1116 llvm::BasicBlock *
EmitCtorCompleteObjectHandler(CodeGenFunction & CGF,const CXXRecordDecl * RD)1117 MicrosoftCXXABI::EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
1118 const CXXRecordDecl *RD) {
1119 llvm::Value *IsMostDerivedClass = getStructorImplicitParamValue(CGF);
1120 assert(IsMostDerivedClass &&
1121 "ctor for a class with virtual bases must have an implicit parameter");
1122 llvm::Value *IsCompleteObject =
1123 CGF.Builder.CreateIsNotNull(IsMostDerivedClass, "is_complete_object");
1124
1125 llvm::BasicBlock *CallVbaseCtorsBB = CGF.createBasicBlock("ctor.init_vbases");
1126 llvm::BasicBlock *SkipVbaseCtorsBB = CGF.createBasicBlock("ctor.skip_vbases");
1127 CGF.Builder.CreateCondBr(IsCompleteObject,
1128 CallVbaseCtorsBB, SkipVbaseCtorsBB);
1129
1130 CGF.EmitBlock(CallVbaseCtorsBB);
1131
1132 // Fill in the vbtable pointers here.
1133 EmitVBPtrStores(CGF, RD);
1134
1135 // CGF will put the base ctor calls in this basic block for us later.
1136
1137 return SkipVbaseCtorsBB;
1138 }
1139
1140 llvm::BasicBlock *
EmitDtorCompleteObjectHandler(CodeGenFunction & CGF)1141 MicrosoftCXXABI::EmitDtorCompleteObjectHandler(CodeGenFunction &CGF) {
1142 llvm::Value *IsMostDerivedClass = getStructorImplicitParamValue(CGF);
1143 assert(IsMostDerivedClass &&
1144 "ctor for a class with virtual bases must have an implicit parameter");
1145 llvm::Value *IsCompleteObject =
1146 CGF.Builder.CreateIsNotNull(IsMostDerivedClass, "is_complete_object");
1147
1148 llvm::BasicBlock *CallVbaseDtorsBB = CGF.createBasicBlock("Dtor.dtor_vbases");
1149 llvm::BasicBlock *SkipVbaseDtorsBB = CGF.createBasicBlock("Dtor.skip_vbases");
1150 CGF.Builder.CreateCondBr(IsCompleteObject,
1151 CallVbaseDtorsBB, SkipVbaseDtorsBB);
1152
1153 CGF.EmitBlock(CallVbaseDtorsBB);
1154 // CGF will put the base dtor calls in this basic block for us later.
1155
1156 return SkipVbaseDtorsBB;
1157 }
1158
initializeHiddenVirtualInheritanceMembers(CodeGenFunction & CGF,const CXXRecordDecl * RD)1159 void MicrosoftCXXABI::initializeHiddenVirtualInheritanceMembers(
1160 CodeGenFunction &CGF, const CXXRecordDecl *RD) {
1161 // In most cases, an override for a vbase virtual method can adjust
1162 // the "this" parameter by applying a constant offset.
1163 // However, this is not enough while a constructor or a destructor of some
1164 // class X is being executed if all the following conditions are met:
1165 // - X has virtual bases, (1)
1166 // - X overrides a virtual method M of a vbase Y, (2)
1167 // - X itself is a vbase of the most derived class.
1168 //
1169 // If (1) and (2) are true, the vtorDisp for vbase Y is a hidden member of X
1170 // which holds the extra amount of "this" adjustment we must do when we use
1171 // the X vftables (i.e. during X ctor or dtor).
1172 // Outside the ctors and dtors, the values of vtorDisps are zero.
1173
1174 const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
1175 typedef ASTRecordLayout::VBaseOffsetsMapTy VBOffsets;
1176 const VBOffsets &VBaseMap = Layout.getVBaseOffsetsMap();
1177 CGBuilderTy &Builder = CGF.Builder;
1178
1179 unsigned AS = getThisAddress(CGF).getAddressSpace();
1180 llvm::Value *Int8This = nullptr; // Initialize lazily.
1181
1182 for (const CXXBaseSpecifier &S : RD->vbases()) {
1183 const CXXRecordDecl *VBase = S.getType()->getAsCXXRecordDecl();
1184 auto I = VBaseMap.find(VBase);
1185 assert(I != VBaseMap.end());
1186 if (!I->second.hasVtorDisp())
1187 continue;
1188
1189 llvm::Value *VBaseOffset =
1190 GetVirtualBaseClassOffset(CGF, getThisAddress(CGF), RD, VBase);
1191 uint64_t ConstantVBaseOffset = I->second.VBaseOffset.getQuantity();
1192
1193 // vtorDisp_for_vbase = vbptr[vbase_idx] - offsetof(RD, vbase).
1194 llvm::Value *VtorDispValue = Builder.CreateSub(
1195 VBaseOffset, llvm::ConstantInt::get(CGM.PtrDiffTy, ConstantVBaseOffset),
1196 "vtordisp.value");
1197 VtorDispValue = Builder.CreateTruncOrBitCast(VtorDispValue, CGF.Int32Ty);
1198
1199 if (!Int8This)
1200 Int8This = Builder.CreateBitCast(getThisValue(CGF),
1201 CGF.Int8Ty->getPointerTo(AS));
1202 llvm::Value *VtorDispPtr = Builder.CreateInBoundsGEP(Int8This, VBaseOffset);
1203 // vtorDisp is always the 32-bits before the vbase in the class layout.
1204 VtorDispPtr = Builder.CreateConstGEP1_32(VtorDispPtr, -4);
1205 VtorDispPtr = Builder.CreateBitCast(
1206 VtorDispPtr, CGF.Int32Ty->getPointerTo(AS), "vtordisp.ptr");
1207
1208 Builder.CreateAlignedStore(VtorDispValue, VtorDispPtr,
1209 CharUnits::fromQuantity(4));
1210 }
1211 }
1212
hasDefaultCXXMethodCC(ASTContext & Context,const CXXMethodDecl * MD)1213 static bool hasDefaultCXXMethodCC(ASTContext &Context,
1214 const CXXMethodDecl *MD) {
1215 CallingConv ExpectedCallingConv = Context.getDefaultCallingConvention(
1216 /*IsVariadic=*/false, /*IsCXXMethod=*/true);
1217 CallingConv ActualCallingConv =
1218 MD->getType()->castAs<FunctionProtoType>()->getCallConv();
1219 return ExpectedCallingConv == ActualCallingConv;
1220 }
1221
EmitCXXConstructors(const CXXConstructorDecl * D)1222 void MicrosoftCXXABI::EmitCXXConstructors(const CXXConstructorDecl *D) {
1223 // There's only one constructor type in this ABI.
1224 CGM.EmitGlobal(GlobalDecl(D, Ctor_Complete));
1225
1226 // Exported default constructors either have a simple call-site where they use
1227 // the typical calling convention and have a single 'this' pointer for an
1228 // argument -or- they get a wrapper function which appropriately thunks to the
1229 // real default constructor. This thunk is the default constructor closure.
1230 if (D->hasAttr<DLLExportAttr>() && D->isDefaultConstructor())
1231 if (!hasDefaultCXXMethodCC(getContext(), D) || D->getNumParams() != 0) {
1232 llvm::Function *Fn = getAddrOfCXXCtorClosure(D, Ctor_DefaultClosure);
1233 Fn->setLinkage(llvm::GlobalValue::WeakODRLinkage);
1234 CGM.setGVProperties(Fn, D);
1235 }
1236 }
1237
EmitVBPtrStores(CodeGenFunction & CGF,const CXXRecordDecl * RD)1238 void MicrosoftCXXABI::EmitVBPtrStores(CodeGenFunction &CGF,
1239 const CXXRecordDecl *RD) {
1240 Address This = getThisAddress(CGF);
1241 This = CGF.Builder.CreateElementBitCast(This, CGM.Int8Ty, "this.int8");
1242 const ASTContext &Context = getContext();
1243 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1244
1245 const VBTableGlobals &VBGlobals = enumerateVBTables(RD);
1246 for (unsigned I = 0, E = VBGlobals.VBTables->size(); I != E; ++I) {
1247 const std::unique_ptr<VPtrInfo> &VBT = (*VBGlobals.VBTables)[I];
1248 llvm::GlobalVariable *GV = VBGlobals.Globals[I];
1249 const ASTRecordLayout &SubobjectLayout =
1250 Context.getASTRecordLayout(VBT->IntroducingObject);
1251 CharUnits Offs = VBT->NonVirtualOffset;
1252 Offs += SubobjectLayout.getVBPtrOffset();
1253 if (VBT->getVBaseWithVPtr())
1254 Offs += Layout.getVBaseClassOffset(VBT->getVBaseWithVPtr());
1255 Address VBPtr = CGF.Builder.CreateConstInBoundsByteGEP(This, Offs);
1256 llvm::Value *GVPtr =
1257 CGF.Builder.CreateConstInBoundsGEP2_32(GV->getValueType(), GV, 0, 0);
1258 VBPtr = CGF.Builder.CreateElementBitCast(VBPtr, GVPtr->getType(),
1259 "vbptr." + VBT->ObjectWithVPtr->getName());
1260 CGF.Builder.CreateStore(GVPtr, VBPtr);
1261 }
1262 }
1263
1264 CGCXXABI::AddedStructorArgs
buildStructorSignature(GlobalDecl GD,SmallVectorImpl<CanQualType> & ArgTys)1265 MicrosoftCXXABI::buildStructorSignature(GlobalDecl GD,
1266 SmallVectorImpl<CanQualType> &ArgTys) {
1267 AddedStructorArgs Added;
1268 // TODO: 'for base' flag
1269 if (isa<CXXDestructorDecl>(GD.getDecl()) &&
1270 GD.getDtorType() == Dtor_Deleting) {
1271 // The scalar deleting destructor takes an implicit int parameter.
1272 ArgTys.push_back(getContext().IntTy);
1273 ++Added.Suffix;
1274 }
1275 auto *CD = dyn_cast<CXXConstructorDecl>(GD.getDecl());
1276 if (!CD)
1277 return Added;
1278
1279 // All parameters are already in place except is_most_derived, which goes
1280 // after 'this' if it's variadic and last if it's not.
1281
1282 const CXXRecordDecl *Class = CD->getParent();
1283 const FunctionProtoType *FPT = CD->getType()->castAs<FunctionProtoType>();
1284 if (Class->getNumVBases()) {
1285 if (FPT->isVariadic()) {
1286 ArgTys.insert(ArgTys.begin() + 1, getContext().IntTy);
1287 ++Added.Prefix;
1288 } else {
1289 ArgTys.push_back(getContext().IntTy);
1290 ++Added.Suffix;
1291 }
1292 }
1293
1294 return Added;
1295 }
1296
setCXXDestructorDLLStorage(llvm::GlobalValue * GV,const CXXDestructorDecl * Dtor,CXXDtorType DT) const1297 void MicrosoftCXXABI::setCXXDestructorDLLStorage(llvm::GlobalValue *GV,
1298 const CXXDestructorDecl *Dtor,
1299 CXXDtorType DT) const {
1300 // Deleting destructor variants are never imported or exported. Give them the
1301 // default storage class.
1302 if (DT == Dtor_Deleting) {
1303 GV->setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass);
1304 } else {
1305 const NamedDecl *ND = Dtor;
1306 CGM.setDLLImportDLLExport(GV, ND);
1307 }
1308 }
1309
getCXXDestructorLinkage(GVALinkage Linkage,const CXXDestructorDecl * Dtor,CXXDtorType DT) const1310 llvm::GlobalValue::LinkageTypes MicrosoftCXXABI::getCXXDestructorLinkage(
1311 GVALinkage Linkage, const CXXDestructorDecl *Dtor, CXXDtorType DT) const {
1312 // Internal things are always internal, regardless of attributes. After this,
1313 // we know the thunk is externally visible.
1314 if (Linkage == GVA_Internal)
1315 return llvm::GlobalValue::InternalLinkage;
1316
1317 switch (DT) {
1318 case Dtor_Base:
1319 // The base destructor most closely tracks the user-declared constructor, so
1320 // we delegate back to the normal declarator case.
1321 return CGM.getLLVMLinkageForDeclarator(Dtor, Linkage,
1322 /*IsConstantVariable=*/false);
1323 case Dtor_Complete:
1324 // The complete destructor is like an inline function, but it may be
1325 // imported and therefore must be exported as well. This requires changing
1326 // the linkage if a DLL attribute is present.
1327 if (Dtor->hasAttr<DLLExportAttr>())
1328 return llvm::GlobalValue::WeakODRLinkage;
1329 if (Dtor->hasAttr<DLLImportAttr>())
1330 return llvm::GlobalValue::AvailableExternallyLinkage;
1331 return llvm::GlobalValue::LinkOnceODRLinkage;
1332 case Dtor_Deleting:
1333 // Deleting destructors are like inline functions. They have vague linkage
1334 // and are emitted everywhere they are used. They are internal if the class
1335 // is internal.
1336 return llvm::GlobalValue::LinkOnceODRLinkage;
1337 case Dtor_Comdat:
1338 llvm_unreachable("MS C++ ABI does not support comdat dtors");
1339 }
1340 llvm_unreachable("invalid dtor type");
1341 }
1342
EmitCXXDestructors(const CXXDestructorDecl * D)1343 void MicrosoftCXXABI::EmitCXXDestructors(const CXXDestructorDecl *D) {
1344 // The TU defining a dtor is only guaranteed to emit a base destructor. All
1345 // other destructor variants are delegating thunks.
1346 CGM.EmitGlobal(GlobalDecl(D, Dtor_Base));
1347
1348 // If the class is dllexported, emit the complete (vbase) destructor wherever
1349 // the base dtor is emitted.
1350 // FIXME: To match MSVC, this should only be done when the class is exported
1351 // with -fdllexport-inlines enabled.
1352 if (D->getParent()->getNumVBases() > 0 && D->hasAttr<DLLExportAttr>())
1353 CGM.EmitGlobal(GlobalDecl(D, Dtor_Complete));
1354 }
1355
1356 CharUnits
getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD)1357 MicrosoftCXXABI::getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) {
1358 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
1359
1360 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1361 // Complete destructors take a pointer to the complete object as a
1362 // parameter, thus don't need this adjustment.
1363 if (GD.getDtorType() == Dtor_Complete)
1364 return CharUnits();
1365
1366 // There's no Dtor_Base in vftable but it shares the this adjustment with
1367 // the deleting one, so look it up instead.
1368 GD = GlobalDecl(DD, Dtor_Deleting);
1369 }
1370
1371 MethodVFTableLocation ML =
1372 CGM.getMicrosoftVTableContext().getMethodVFTableLocation(GD);
1373 CharUnits Adjustment = ML.VFPtrOffset;
1374
1375 // Normal virtual instance methods need to adjust from the vfptr that first
1376 // defined the virtual method to the virtual base subobject, but destructors
1377 // do not. The vector deleting destructor thunk applies this adjustment for
1378 // us if necessary.
1379 if (isa<CXXDestructorDecl>(MD))
1380 Adjustment = CharUnits::Zero();
1381
1382 if (ML.VBase) {
1383 const ASTRecordLayout &DerivedLayout =
1384 getContext().getASTRecordLayout(MD->getParent());
1385 Adjustment += DerivedLayout.getVBaseClassOffset(ML.VBase);
1386 }
1387
1388 return Adjustment;
1389 }
1390
adjustThisArgumentForVirtualFunctionCall(CodeGenFunction & CGF,GlobalDecl GD,Address This,bool VirtualCall)1391 Address MicrosoftCXXABI::adjustThisArgumentForVirtualFunctionCall(
1392 CodeGenFunction &CGF, GlobalDecl GD, Address This,
1393 bool VirtualCall) {
1394 if (!VirtualCall) {
1395 // If the call of a virtual function is not virtual, we just have to
1396 // compensate for the adjustment the virtual function does in its prologue.
1397 CharUnits Adjustment = getVirtualFunctionPrologueThisAdjustment(GD);
1398 if (Adjustment.isZero())
1399 return This;
1400
1401 This = CGF.Builder.CreateElementBitCast(This, CGF.Int8Ty);
1402 assert(Adjustment.isPositive());
1403 return CGF.Builder.CreateConstByteGEP(This, Adjustment);
1404 }
1405
1406 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
1407
1408 GlobalDecl LookupGD = GD;
1409 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1410 // Complete dtors take a pointer to the complete object,
1411 // thus don't need adjustment.
1412 if (GD.getDtorType() == Dtor_Complete)
1413 return This;
1414
1415 // There's only Dtor_Deleting in vftable but it shares the this adjustment
1416 // with the base one, so look up the deleting one instead.
1417 LookupGD = GlobalDecl(DD, Dtor_Deleting);
1418 }
1419 MethodVFTableLocation ML =
1420 CGM.getMicrosoftVTableContext().getMethodVFTableLocation(LookupGD);
1421
1422 CharUnits StaticOffset = ML.VFPtrOffset;
1423
1424 // Base destructors expect 'this' to point to the beginning of the base
1425 // subobject, not the first vfptr that happens to contain the virtual dtor.
1426 // However, we still need to apply the virtual base adjustment.
1427 if (isa<CXXDestructorDecl>(MD) && GD.getDtorType() == Dtor_Base)
1428 StaticOffset = CharUnits::Zero();
1429
1430 Address Result = This;
1431 if (ML.VBase) {
1432 Result = CGF.Builder.CreateElementBitCast(Result, CGF.Int8Ty);
1433
1434 const CXXRecordDecl *Derived = MD->getParent();
1435 const CXXRecordDecl *VBase = ML.VBase;
1436 llvm::Value *VBaseOffset =
1437 GetVirtualBaseClassOffset(CGF, Result, Derived, VBase);
1438 llvm::Value *VBasePtr =
1439 CGF.Builder.CreateInBoundsGEP(Result.getPointer(), VBaseOffset);
1440 CharUnits VBaseAlign =
1441 CGF.CGM.getVBaseAlignment(Result.getAlignment(), Derived, VBase);
1442 Result = Address(VBasePtr, VBaseAlign);
1443 }
1444 if (!StaticOffset.isZero()) {
1445 assert(StaticOffset.isPositive());
1446 Result = CGF.Builder.CreateElementBitCast(Result, CGF.Int8Ty);
1447 if (ML.VBase) {
1448 // Non-virtual adjustment might result in a pointer outside the allocated
1449 // object, e.g. if the final overrider class is laid out after the virtual
1450 // base that declares a method in the most derived class.
1451 // FIXME: Update the code that emits this adjustment in thunks prologues.
1452 Result = CGF.Builder.CreateConstByteGEP(Result, StaticOffset);
1453 } else {
1454 Result = CGF.Builder.CreateConstInBoundsByteGEP(Result, StaticOffset);
1455 }
1456 }
1457 return Result;
1458 }
1459
addImplicitStructorParams(CodeGenFunction & CGF,QualType & ResTy,FunctionArgList & Params)1460 void MicrosoftCXXABI::addImplicitStructorParams(CodeGenFunction &CGF,
1461 QualType &ResTy,
1462 FunctionArgList &Params) {
1463 ASTContext &Context = getContext();
1464 const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
1465 assert(isa<CXXConstructorDecl>(MD) || isa<CXXDestructorDecl>(MD));
1466 if (isa<CXXConstructorDecl>(MD) && MD->getParent()->getNumVBases()) {
1467 auto *IsMostDerived = ImplicitParamDecl::Create(
1468 Context, /*DC=*/nullptr, CGF.CurGD.getDecl()->getLocation(),
1469 &Context.Idents.get("is_most_derived"), Context.IntTy,
1470 ImplicitParamDecl::Other);
1471 // The 'most_derived' parameter goes second if the ctor is variadic and last
1472 // if it's not. Dtors can't be variadic.
1473 const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>();
1474 if (FPT->isVariadic())
1475 Params.insert(Params.begin() + 1, IsMostDerived);
1476 else
1477 Params.push_back(IsMostDerived);
1478 getStructorImplicitParamDecl(CGF) = IsMostDerived;
1479 } else if (isDeletingDtor(CGF.CurGD)) {
1480 auto *ShouldDelete = ImplicitParamDecl::Create(
1481 Context, /*DC=*/nullptr, CGF.CurGD.getDecl()->getLocation(),
1482 &Context.Idents.get("should_call_delete"), Context.IntTy,
1483 ImplicitParamDecl::Other);
1484 Params.push_back(ShouldDelete);
1485 getStructorImplicitParamDecl(CGF) = ShouldDelete;
1486 }
1487 }
1488
EmitInstanceFunctionProlog(CodeGenFunction & CGF)1489 void MicrosoftCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) {
1490 // Naked functions have no prolog.
1491 if (CGF.CurFuncDecl && CGF.CurFuncDecl->hasAttr<NakedAttr>())
1492 return;
1493
1494 // Overridden virtual methods of non-primary bases need to adjust the incoming
1495 // 'this' pointer in the prologue. In this hierarchy, C::b will subtract
1496 // sizeof(void*) to adjust from B* to C*:
1497 // struct A { virtual void a(); };
1498 // struct B { virtual void b(); };
1499 // struct C : A, B { virtual void b(); };
1500 //
1501 // Leave the value stored in the 'this' alloca unadjusted, so that the
1502 // debugger sees the unadjusted value. Microsoft debuggers require this, and
1503 // will apply the ThisAdjustment in the method type information.
1504 // FIXME: Do something better for DWARF debuggers, which won't expect this,
1505 // without making our codegen depend on debug info settings.
1506 llvm::Value *This = loadIncomingCXXThis(CGF);
1507 const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
1508 if (!CGF.CurFuncIsThunk && MD->isVirtual()) {
1509 CharUnits Adjustment = getVirtualFunctionPrologueThisAdjustment(CGF.CurGD);
1510 if (!Adjustment.isZero()) {
1511 unsigned AS = cast<llvm::PointerType>(This->getType())->getAddressSpace();
1512 llvm::Type *charPtrTy = CGF.Int8Ty->getPointerTo(AS),
1513 *thisTy = This->getType();
1514 This = CGF.Builder.CreateBitCast(This, charPtrTy);
1515 assert(Adjustment.isPositive());
1516 This = CGF.Builder.CreateConstInBoundsGEP1_32(CGF.Int8Ty, This,
1517 -Adjustment.getQuantity());
1518 This = CGF.Builder.CreateBitCast(This, thisTy, "this.adjusted");
1519 }
1520 }
1521 setCXXABIThisValue(CGF, This);
1522
1523 // If this is a function that the ABI specifies returns 'this', initialize
1524 // the return slot to 'this' at the start of the function.
1525 //
1526 // Unlike the setting of return types, this is done within the ABI
1527 // implementation instead of by clients of CGCXXABI because:
1528 // 1) getThisValue is currently protected
1529 // 2) in theory, an ABI could implement 'this' returns some other way;
1530 // HasThisReturn only specifies a contract, not the implementation
1531 if (HasThisReturn(CGF.CurGD))
1532 CGF.Builder.CreateStore(getThisValue(CGF), CGF.ReturnValue);
1533 else if (hasMostDerivedReturn(CGF.CurGD))
1534 CGF.Builder.CreateStore(CGF.EmitCastToVoidPtr(getThisValue(CGF)),
1535 CGF.ReturnValue);
1536
1537 if (isa<CXXConstructorDecl>(MD) && MD->getParent()->getNumVBases()) {
1538 assert(getStructorImplicitParamDecl(CGF) &&
1539 "no implicit parameter for a constructor with virtual bases?");
1540 getStructorImplicitParamValue(CGF)
1541 = CGF.Builder.CreateLoad(
1542 CGF.GetAddrOfLocalVar(getStructorImplicitParamDecl(CGF)),
1543 "is_most_derived");
1544 }
1545
1546 if (isDeletingDtor(CGF.CurGD)) {
1547 assert(getStructorImplicitParamDecl(CGF) &&
1548 "no implicit parameter for a deleting destructor?");
1549 getStructorImplicitParamValue(CGF)
1550 = CGF.Builder.CreateLoad(
1551 CGF.GetAddrOfLocalVar(getStructorImplicitParamDecl(CGF)),
1552 "should_call_delete");
1553 }
1554 }
1555
addImplicitConstructorArgs(CodeGenFunction & CGF,const CXXConstructorDecl * D,CXXCtorType Type,bool ForVirtualBase,bool Delegating,CallArgList & Args)1556 CGCXXABI::AddedStructorArgs MicrosoftCXXABI::addImplicitConstructorArgs(
1557 CodeGenFunction &CGF, const CXXConstructorDecl *D, CXXCtorType Type,
1558 bool ForVirtualBase, bool Delegating, CallArgList &Args) {
1559 assert(Type == Ctor_Complete || Type == Ctor_Base);
1560
1561 // Check if we need a 'most_derived' parameter.
1562 if (!D->getParent()->getNumVBases())
1563 return AddedStructorArgs{};
1564
1565 // Add the 'most_derived' argument second if we are variadic or last if not.
1566 const FunctionProtoType *FPT = D->getType()->castAs<FunctionProtoType>();
1567 llvm::Value *MostDerivedArg;
1568 if (Delegating) {
1569 MostDerivedArg = getStructorImplicitParamValue(CGF);
1570 } else {
1571 MostDerivedArg = llvm::ConstantInt::get(CGM.Int32Ty, Type == Ctor_Complete);
1572 }
1573 RValue RV = RValue::get(MostDerivedArg);
1574 if (FPT->isVariadic()) {
1575 Args.insert(Args.begin() + 1, CallArg(RV, getContext().IntTy));
1576 return AddedStructorArgs::prefix(1);
1577 }
1578 Args.add(RV, getContext().IntTy);
1579 return AddedStructorArgs::suffix(1);
1580 }
1581
EmitDestructorCall(CodeGenFunction & CGF,const CXXDestructorDecl * DD,CXXDtorType Type,bool ForVirtualBase,bool Delegating,Address This,QualType ThisTy)1582 void MicrosoftCXXABI::EmitDestructorCall(CodeGenFunction &CGF,
1583 const CXXDestructorDecl *DD,
1584 CXXDtorType Type, bool ForVirtualBase,
1585 bool Delegating, Address This,
1586 QualType ThisTy) {
1587 // Use the base destructor variant in place of the complete destructor variant
1588 // if the class has no virtual bases. This effectively implements some of the
1589 // -mconstructor-aliases optimization, but as part of the MS C++ ABI.
1590 if (Type == Dtor_Complete && DD->getParent()->getNumVBases() == 0)
1591 Type = Dtor_Base;
1592
1593 GlobalDecl GD(DD, Type);
1594 CGCallee Callee = CGCallee::forDirect(CGM.getAddrOfCXXStructor(GD), GD);
1595
1596 if (DD->isVirtual()) {
1597 assert(Type != CXXDtorType::Dtor_Deleting &&
1598 "The deleting destructor should only be called via a virtual call");
1599 This = adjustThisArgumentForVirtualFunctionCall(CGF, GlobalDecl(DD, Type),
1600 This, false);
1601 }
1602
1603 llvm::BasicBlock *BaseDtorEndBB = nullptr;
1604 if (ForVirtualBase && isa<CXXConstructorDecl>(CGF.CurCodeDecl)) {
1605 BaseDtorEndBB = EmitDtorCompleteObjectHandler(CGF);
1606 }
1607
1608 CGF.EmitCXXDestructorCall(GD, Callee, This.getPointer(), ThisTy,
1609 /*ImplicitParam=*/nullptr,
1610 /*ImplicitParamTy=*/QualType(), nullptr);
1611 if (BaseDtorEndBB) {
1612 // Complete object handler should continue to be the remaining
1613 CGF.Builder.CreateBr(BaseDtorEndBB);
1614 CGF.EmitBlock(BaseDtorEndBB);
1615 }
1616 }
1617
emitVTableTypeMetadata(const VPtrInfo & Info,const CXXRecordDecl * RD,llvm::GlobalVariable * VTable)1618 void MicrosoftCXXABI::emitVTableTypeMetadata(const VPtrInfo &Info,
1619 const CXXRecordDecl *RD,
1620 llvm::GlobalVariable *VTable) {
1621 if (!CGM.getCodeGenOpts().LTOUnit)
1622 return;
1623
1624 // The location of the first virtual function pointer in the virtual table,
1625 // aka the "address point" on Itanium. This is at offset 0 if RTTI is
1626 // disabled, or sizeof(void*) if RTTI is enabled.
1627 CharUnits AddressPoint =
1628 getContext().getLangOpts().RTTIData
1629 ? getContext().toCharUnitsFromBits(
1630 getContext().getTargetInfo().getPointerWidth(0))
1631 : CharUnits::Zero();
1632
1633 if (Info.PathToIntroducingObject.empty()) {
1634 CGM.AddVTableTypeMetadata(VTable, AddressPoint, RD);
1635 return;
1636 }
1637
1638 // Add a bitset entry for the least derived base belonging to this vftable.
1639 CGM.AddVTableTypeMetadata(VTable, AddressPoint,
1640 Info.PathToIntroducingObject.back());
1641
1642 // Add a bitset entry for each derived class that is laid out at the same
1643 // offset as the least derived base.
1644 for (unsigned I = Info.PathToIntroducingObject.size() - 1; I != 0; --I) {
1645 const CXXRecordDecl *DerivedRD = Info.PathToIntroducingObject[I - 1];
1646 const CXXRecordDecl *BaseRD = Info.PathToIntroducingObject[I];
1647
1648 const ASTRecordLayout &Layout =
1649 getContext().getASTRecordLayout(DerivedRD);
1650 CharUnits Offset;
1651 auto VBI = Layout.getVBaseOffsetsMap().find(BaseRD);
1652 if (VBI == Layout.getVBaseOffsetsMap().end())
1653 Offset = Layout.getBaseClassOffset(BaseRD);
1654 else
1655 Offset = VBI->second.VBaseOffset;
1656 if (!Offset.isZero())
1657 return;
1658 CGM.AddVTableTypeMetadata(VTable, AddressPoint, DerivedRD);
1659 }
1660
1661 // Finally do the same for the most derived class.
1662 if (Info.FullOffsetInMDC.isZero())
1663 CGM.AddVTableTypeMetadata(VTable, AddressPoint, RD);
1664 }
1665
emitVTableDefinitions(CodeGenVTables & CGVT,const CXXRecordDecl * RD)1666 void MicrosoftCXXABI::emitVTableDefinitions(CodeGenVTables &CGVT,
1667 const CXXRecordDecl *RD) {
1668 MicrosoftVTableContext &VFTContext = CGM.getMicrosoftVTableContext();
1669 const VPtrInfoVector &VFPtrs = VFTContext.getVFPtrOffsets(RD);
1670
1671 for (const std::unique_ptr<VPtrInfo>& Info : VFPtrs) {
1672 llvm::GlobalVariable *VTable = getAddrOfVTable(RD, Info->FullOffsetInMDC);
1673 if (VTable->hasInitializer())
1674 continue;
1675
1676 const VTableLayout &VTLayout =
1677 VFTContext.getVFTableLayout(RD, Info->FullOffsetInMDC);
1678
1679 llvm::Constant *RTTI = nullptr;
1680 if (any_of(VTLayout.vtable_components(),
1681 [](const VTableComponent &VTC) { return VTC.isRTTIKind(); }))
1682 RTTI = getMSCompleteObjectLocator(RD, *Info);
1683
1684 ConstantInitBuilder Builder(CGM);
1685 auto Components = Builder.beginStruct();
1686 CGVT.createVTableInitializer(Components, VTLayout, RTTI);
1687 Components.finishAndSetAsInitializer(VTable);
1688
1689 emitVTableTypeMetadata(*Info, RD, VTable);
1690 }
1691 }
1692
isVirtualOffsetNeededForVTableField(CodeGenFunction & CGF,CodeGenFunction::VPtr Vptr)1693 bool MicrosoftCXXABI::isVirtualOffsetNeededForVTableField(
1694 CodeGenFunction &CGF, CodeGenFunction::VPtr Vptr) {
1695 return Vptr.NearestVBase != nullptr;
1696 }
1697
getVTableAddressPointInStructor(CodeGenFunction & CGF,const CXXRecordDecl * VTableClass,BaseSubobject Base,const CXXRecordDecl * NearestVBase)1698 llvm::Value *MicrosoftCXXABI::getVTableAddressPointInStructor(
1699 CodeGenFunction &CGF, const CXXRecordDecl *VTableClass, BaseSubobject Base,
1700 const CXXRecordDecl *NearestVBase) {
1701 llvm::Constant *VTableAddressPoint = getVTableAddressPoint(Base, VTableClass);
1702 if (!VTableAddressPoint) {
1703 assert(Base.getBase()->getNumVBases() &&
1704 !getContext().getASTRecordLayout(Base.getBase()).hasOwnVFPtr());
1705 }
1706 return VTableAddressPoint;
1707 }
1708
mangleVFTableName(MicrosoftMangleContext & MangleContext,const CXXRecordDecl * RD,const VPtrInfo & VFPtr,SmallString<256> & Name)1709 static void mangleVFTableName(MicrosoftMangleContext &MangleContext,
1710 const CXXRecordDecl *RD, const VPtrInfo &VFPtr,
1711 SmallString<256> &Name) {
1712 llvm::raw_svector_ostream Out(Name);
1713 MangleContext.mangleCXXVFTable(RD, VFPtr.MangledPath, Out);
1714 }
1715
1716 llvm::Constant *
getVTableAddressPoint(BaseSubobject Base,const CXXRecordDecl * VTableClass)1717 MicrosoftCXXABI::getVTableAddressPoint(BaseSubobject Base,
1718 const CXXRecordDecl *VTableClass) {
1719 (void)getAddrOfVTable(VTableClass, Base.getBaseOffset());
1720 VFTableIdTy ID(VTableClass, Base.getBaseOffset());
1721 return VFTablesMap[ID];
1722 }
1723
getVTableAddressPointForConstExpr(BaseSubobject Base,const CXXRecordDecl * VTableClass)1724 llvm::Constant *MicrosoftCXXABI::getVTableAddressPointForConstExpr(
1725 BaseSubobject Base, const CXXRecordDecl *VTableClass) {
1726 llvm::Constant *VFTable = getVTableAddressPoint(Base, VTableClass);
1727 assert(VFTable && "Couldn't find a vftable for the given base?");
1728 return VFTable;
1729 }
1730
getAddrOfVTable(const CXXRecordDecl * RD,CharUnits VPtrOffset)1731 llvm::GlobalVariable *MicrosoftCXXABI::getAddrOfVTable(const CXXRecordDecl *RD,
1732 CharUnits VPtrOffset) {
1733 // getAddrOfVTable may return 0 if asked to get an address of a vtable which
1734 // shouldn't be used in the given record type. We want to cache this result in
1735 // VFTablesMap, thus a simple zero check is not sufficient.
1736
1737 VFTableIdTy ID(RD, VPtrOffset);
1738 VTablesMapTy::iterator I;
1739 bool Inserted;
1740 std::tie(I, Inserted) = VTablesMap.insert(std::make_pair(ID, nullptr));
1741 if (!Inserted)
1742 return I->second;
1743
1744 llvm::GlobalVariable *&VTable = I->second;
1745
1746 MicrosoftVTableContext &VTContext = CGM.getMicrosoftVTableContext();
1747 const VPtrInfoVector &VFPtrs = VTContext.getVFPtrOffsets(RD);
1748
1749 if (DeferredVFTables.insert(RD).second) {
1750 // We haven't processed this record type before.
1751 // Queue up this vtable for possible deferred emission.
1752 CGM.addDeferredVTable(RD);
1753
1754 #ifndef NDEBUG
1755 // Create all the vftables at once in order to make sure each vftable has
1756 // a unique mangled name.
1757 llvm::StringSet<> ObservedMangledNames;
1758 for (size_t J = 0, F = VFPtrs.size(); J != F; ++J) {
1759 SmallString<256> Name;
1760 mangleVFTableName(getMangleContext(), RD, *VFPtrs[J], Name);
1761 if (!ObservedMangledNames.insert(Name.str()).second)
1762 llvm_unreachable("Already saw this mangling before?");
1763 }
1764 #endif
1765 }
1766
1767 const std::unique_ptr<VPtrInfo> *VFPtrI = std::find_if(
1768 VFPtrs.begin(), VFPtrs.end(), [&](const std::unique_ptr<VPtrInfo>& VPI) {
1769 return VPI->FullOffsetInMDC == VPtrOffset;
1770 });
1771 if (VFPtrI == VFPtrs.end()) {
1772 VFTablesMap[ID] = nullptr;
1773 return nullptr;
1774 }
1775 const std::unique_ptr<VPtrInfo> &VFPtr = *VFPtrI;
1776
1777 SmallString<256> VFTableName;
1778 mangleVFTableName(getMangleContext(), RD, *VFPtr, VFTableName);
1779
1780 // Classes marked __declspec(dllimport) need vftables generated on the
1781 // import-side in order to support features like constexpr. No other
1782 // translation unit relies on the emission of the local vftable, translation
1783 // units are expected to generate them as needed.
1784 //
1785 // Because of this unique behavior, we maintain this logic here instead of
1786 // getVTableLinkage.
1787 llvm::GlobalValue::LinkageTypes VFTableLinkage =
1788 RD->hasAttr<DLLImportAttr>() ? llvm::GlobalValue::LinkOnceODRLinkage
1789 : CGM.getVTableLinkage(RD);
1790 bool VFTableComesFromAnotherTU =
1791 llvm::GlobalValue::isAvailableExternallyLinkage(VFTableLinkage) ||
1792 llvm::GlobalValue::isExternalLinkage(VFTableLinkage);
1793 bool VTableAliasIsRequred =
1794 !VFTableComesFromAnotherTU && getContext().getLangOpts().RTTIData;
1795
1796 if (llvm::GlobalValue *VFTable =
1797 CGM.getModule().getNamedGlobal(VFTableName)) {
1798 VFTablesMap[ID] = VFTable;
1799 VTable = VTableAliasIsRequred
1800 ? cast<llvm::GlobalVariable>(
1801 cast<llvm::GlobalAlias>(VFTable)->getBaseObject())
1802 : cast<llvm::GlobalVariable>(VFTable);
1803 return VTable;
1804 }
1805
1806 const VTableLayout &VTLayout =
1807 VTContext.getVFTableLayout(RD, VFPtr->FullOffsetInMDC);
1808 llvm::GlobalValue::LinkageTypes VTableLinkage =
1809 VTableAliasIsRequred ? llvm::GlobalValue::PrivateLinkage : VFTableLinkage;
1810
1811 StringRef VTableName = VTableAliasIsRequred ? StringRef() : VFTableName.str();
1812
1813 llvm::Type *VTableType = CGM.getVTables().getVTableType(VTLayout);
1814
1815 // Create a backing variable for the contents of VTable. The VTable may
1816 // or may not include space for a pointer to RTTI data.
1817 llvm::GlobalValue *VFTable;
1818 VTable = new llvm::GlobalVariable(CGM.getModule(), VTableType,
1819 /*isConstant=*/true, VTableLinkage,
1820 /*Initializer=*/nullptr, VTableName);
1821 VTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
1822
1823 llvm::Comdat *C = nullptr;
1824 if (!VFTableComesFromAnotherTU &&
1825 (llvm::GlobalValue::isWeakForLinker(VFTableLinkage) ||
1826 (llvm::GlobalValue::isLocalLinkage(VFTableLinkage) &&
1827 VTableAliasIsRequred)))
1828 C = CGM.getModule().getOrInsertComdat(VFTableName.str());
1829
1830 // Only insert a pointer into the VFTable for RTTI data if we are not
1831 // importing it. We never reference the RTTI data directly so there is no
1832 // need to make room for it.
1833 if (VTableAliasIsRequred) {
1834 llvm::Value *GEPIndices[] = {llvm::ConstantInt::get(CGM.Int32Ty, 0),
1835 llvm::ConstantInt::get(CGM.Int32Ty, 0),
1836 llvm::ConstantInt::get(CGM.Int32Ty, 1)};
1837 // Create a GEP which points just after the first entry in the VFTable,
1838 // this should be the location of the first virtual method.
1839 llvm::Constant *VTableGEP = llvm::ConstantExpr::getInBoundsGetElementPtr(
1840 VTable->getValueType(), VTable, GEPIndices);
1841 if (llvm::GlobalValue::isWeakForLinker(VFTableLinkage)) {
1842 VFTableLinkage = llvm::GlobalValue::ExternalLinkage;
1843 if (C)
1844 C->setSelectionKind(llvm::Comdat::Largest);
1845 }
1846 VFTable = llvm::GlobalAlias::create(CGM.Int8PtrTy,
1847 /*AddressSpace=*/0, VFTableLinkage,
1848 VFTableName.str(), VTableGEP,
1849 &CGM.getModule());
1850 VFTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
1851 } else {
1852 // We don't need a GlobalAlias to be a symbol for the VTable if we won't
1853 // be referencing any RTTI data.
1854 // The GlobalVariable will end up being an appropriate definition of the
1855 // VFTable.
1856 VFTable = VTable;
1857 }
1858 if (C)
1859 VTable->setComdat(C);
1860
1861 if (RD->hasAttr<DLLExportAttr>())
1862 VFTable->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);
1863
1864 VFTablesMap[ID] = VFTable;
1865 return VTable;
1866 }
1867
getVirtualFunctionPointer(CodeGenFunction & CGF,GlobalDecl GD,Address This,llvm::Type * Ty,SourceLocation Loc)1868 CGCallee MicrosoftCXXABI::getVirtualFunctionPointer(CodeGenFunction &CGF,
1869 GlobalDecl GD,
1870 Address This,
1871 llvm::Type *Ty,
1872 SourceLocation Loc) {
1873 CGBuilderTy &Builder = CGF.Builder;
1874
1875 Ty = Ty->getPointerTo()->getPointerTo();
1876 Address VPtr =
1877 adjustThisArgumentForVirtualFunctionCall(CGF, GD, This, true);
1878
1879 auto *MethodDecl = cast<CXXMethodDecl>(GD.getDecl());
1880 llvm::Value *VTable = CGF.GetVTablePtr(VPtr, Ty, MethodDecl->getParent());
1881
1882 MicrosoftVTableContext &VFTContext = CGM.getMicrosoftVTableContext();
1883 MethodVFTableLocation ML = VFTContext.getMethodVFTableLocation(GD);
1884
1885 // Compute the identity of the most derived class whose virtual table is
1886 // located at the MethodVFTableLocation ML.
1887 auto getObjectWithVPtr = [&] {
1888 return llvm::find_if(VFTContext.getVFPtrOffsets(
1889 ML.VBase ? ML.VBase : MethodDecl->getParent()),
1890 [&](const std::unique_ptr<VPtrInfo> &Info) {
1891 return Info->FullOffsetInMDC == ML.VFPtrOffset;
1892 })
1893 ->get()
1894 ->ObjectWithVPtr;
1895 };
1896
1897 llvm::Value *VFunc;
1898 if (CGF.ShouldEmitVTableTypeCheckedLoad(MethodDecl->getParent())) {
1899 VFunc = CGF.EmitVTableTypeCheckedLoad(
1900 getObjectWithVPtr(), VTable,
1901 ML.Index * CGM.getContext().getTargetInfo().getPointerWidth(0) / 8);
1902 } else {
1903 if (CGM.getCodeGenOpts().PrepareForLTO)
1904 CGF.EmitTypeMetadataCodeForVCall(getObjectWithVPtr(), VTable, Loc);
1905
1906 llvm::Value *VFuncPtr =
1907 Builder.CreateConstInBoundsGEP1_64(VTable, ML.Index, "vfn");
1908 VFunc = Builder.CreateAlignedLoad(VFuncPtr, CGF.getPointerAlign());
1909 }
1910
1911 CGCallee Callee(GD, VFunc);
1912 return Callee;
1913 }
1914
EmitVirtualDestructorCall(CodeGenFunction & CGF,const CXXDestructorDecl * Dtor,CXXDtorType DtorType,Address This,DeleteOrMemberCallExpr E)1915 llvm::Value *MicrosoftCXXABI::EmitVirtualDestructorCall(
1916 CodeGenFunction &CGF, const CXXDestructorDecl *Dtor, CXXDtorType DtorType,
1917 Address This, DeleteOrMemberCallExpr E) {
1918 auto *CE = E.dyn_cast<const CXXMemberCallExpr *>();
1919 auto *D = E.dyn_cast<const CXXDeleteExpr *>();
1920 assert((CE != nullptr) ^ (D != nullptr));
1921 assert(CE == nullptr || CE->arg_begin() == CE->arg_end());
1922 assert(DtorType == Dtor_Deleting || DtorType == Dtor_Complete);
1923
1924 // We have only one destructor in the vftable but can get both behaviors
1925 // by passing an implicit int parameter.
1926 GlobalDecl GD(Dtor, Dtor_Deleting);
1927 const CGFunctionInfo *FInfo =
1928 &CGM.getTypes().arrangeCXXStructorDeclaration(GD);
1929 llvm::FunctionType *Ty = CGF.CGM.getTypes().GetFunctionType(*FInfo);
1930 CGCallee Callee = CGCallee::forVirtual(CE, GD, This, Ty);
1931
1932 ASTContext &Context = getContext();
1933 llvm::Value *ImplicitParam = llvm::ConstantInt::get(
1934 llvm::IntegerType::getInt32Ty(CGF.getLLVMContext()),
1935 DtorType == Dtor_Deleting);
1936
1937 QualType ThisTy;
1938 if (CE) {
1939 ThisTy = CE->getObjectType();
1940 } else {
1941 ThisTy = D->getDestroyedType();
1942 }
1943
1944 This = adjustThisArgumentForVirtualFunctionCall(CGF, GD, This, true);
1945 RValue RV = CGF.EmitCXXDestructorCall(GD, Callee, This.getPointer(), ThisTy,
1946 ImplicitParam, Context.IntTy, CE);
1947 return RV.getScalarVal();
1948 }
1949
1950 const VBTableGlobals &
enumerateVBTables(const CXXRecordDecl * RD)1951 MicrosoftCXXABI::enumerateVBTables(const CXXRecordDecl *RD) {
1952 // At this layer, we can key the cache off of a single class, which is much
1953 // easier than caching each vbtable individually.
1954 llvm::DenseMap<const CXXRecordDecl*, VBTableGlobals>::iterator Entry;
1955 bool Added;
1956 std::tie(Entry, Added) =
1957 VBTablesMap.insert(std::make_pair(RD, VBTableGlobals()));
1958 VBTableGlobals &VBGlobals = Entry->second;
1959 if (!Added)
1960 return VBGlobals;
1961
1962 MicrosoftVTableContext &Context = CGM.getMicrosoftVTableContext();
1963 VBGlobals.VBTables = &Context.enumerateVBTables(RD);
1964
1965 // Cache the globals for all vbtables so we don't have to recompute the
1966 // mangled names.
1967 llvm::GlobalVariable::LinkageTypes Linkage = CGM.getVTableLinkage(RD);
1968 for (VPtrInfoVector::const_iterator I = VBGlobals.VBTables->begin(),
1969 E = VBGlobals.VBTables->end();
1970 I != E; ++I) {
1971 VBGlobals.Globals.push_back(getAddrOfVBTable(**I, RD, Linkage));
1972 }
1973
1974 return VBGlobals;
1975 }
1976
1977 llvm::Function *
EmitVirtualMemPtrThunk(const CXXMethodDecl * MD,const MethodVFTableLocation & ML)1978 MicrosoftCXXABI::EmitVirtualMemPtrThunk(const CXXMethodDecl *MD,
1979 const MethodVFTableLocation &ML) {
1980 assert(!isa<CXXConstructorDecl>(MD) && !isa<CXXDestructorDecl>(MD) &&
1981 "can't form pointers to ctors or virtual dtors");
1982
1983 // Calculate the mangled name.
1984 SmallString<256> ThunkName;
1985 llvm::raw_svector_ostream Out(ThunkName);
1986 getMangleContext().mangleVirtualMemPtrThunk(MD, ML, Out);
1987
1988 // If the thunk has been generated previously, just return it.
1989 if (llvm::GlobalValue *GV = CGM.getModule().getNamedValue(ThunkName))
1990 return cast<llvm::Function>(GV);
1991
1992 // Create the llvm::Function.
1993 const CGFunctionInfo &FnInfo =
1994 CGM.getTypes().arrangeUnprototypedMustTailThunk(MD);
1995 llvm::FunctionType *ThunkTy = CGM.getTypes().GetFunctionType(FnInfo);
1996 llvm::Function *ThunkFn =
1997 llvm::Function::Create(ThunkTy, llvm::Function::ExternalLinkage,
1998 ThunkName.str(), &CGM.getModule());
1999 assert(ThunkFn->getName() == ThunkName && "name was uniqued!");
2000
2001 ThunkFn->setLinkage(MD->isExternallyVisible()
2002 ? llvm::GlobalValue::LinkOnceODRLinkage
2003 : llvm::GlobalValue::InternalLinkage);
2004 if (MD->isExternallyVisible())
2005 ThunkFn->setComdat(CGM.getModule().getOrInsertComdat(ThunkFn->getName()));
2006
2007 CGM.SetLLVMFunctionAttributes(MD, FnInfo, ThunkFn);
2008 CGM.SetLLVMFunctionAttributesForDefinition(MD, ThunkFn);
2009
2010 // Add the "thunk" attribute so that LLVM knows that the return type is
2011 // meaningless. These thunks can be used to call functions with differing
2012 // return types, and the caller is required to cast the prototype
2013 // appropriately to extract the correct value.
2014 ThunkFn->addFnAttr("thunk");
2015
2016 // These thunks can be compared, so they are not unnamed.
2017 ThunkFn->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::None);
2018
2019 // Start codegen.
2020 CodeGenFunction CGF(CGM);
2021 CGF.CurGD = GlobalDecl(MD);
2022 CGF.CurFuncIsThunk = true;
2023
2024 // Build FunctionArgs, but only include the implicit 'this' parameter
2025 // declaration.
2026 FunctionArgList FunctionArgs;
2027 buildThisParam(CGF, FunctionArgs);
2028
2029 // Start defining the function.
2030 CGF.StartFunction(GlobalDecl(), FnInfo.getReturnType(), ThunkFn, FnInfo,
2031 FunctionArgs, MD->getLocation(), SourceLocation());
2032 setCXXABIThisValue(CGF, loadIncomingCXXThis(CGF));
2033
2034 // Load the vfptr and then callee from the vftable. The callee should have
2035 // adjusted 'this' so that the vfptr is at offset zero.
2036 llvm::Value *VTable = CGF.GetVTablePtr(
2037 getThisAddress(CGF), ThunkTy->getPointerTo()->getPointerTo(), MD->getParent());
2038
2039 llvm::Value *VFuncPtr =
2040 CGF.Builder.CreateConstInBoundsGEP1_64(VTable, ML.Index, "vfn");
2041 llvm::Value *Callee =
2042 CGF.Builder.CreateAlignedLoad(VFuncPtr, CGF.getPointerAlign());
2043
2044 CGF.EmitMustTailThunk(MD, getThisValue(CGF), {ThunkTy, Callee});
2045
2046 return ThunkFn;
2047 }
2048
emitVirtualInheritanceTables(const CXXRecordDecl * RD)2049 void MicrosoftCXXABI::emitVirtualInheritanceTables(const CXXRecordDecl *RD) {
2050 const VBTableGlobals &VBGlobals = enumerateVBTables(RD);
2051 for (unsigned I = 0, E = VBGlobals.VBTables->size(); I != E; ++I) {
2052 const std::unique_ptr<VPtrInfo>& VBT = (*VBGlobals.VBTables)[I];
2053 llvm::GlobalVariable *GV = VBGlobals.Globals[I];
2054 if (GV->isDeclaration())
2055 emitVBTableDefinition(*VBT, RD, GV);
2056 }
2057 }
2058
2059 llvm::GlobalVariable *
getAddrOfVBTable(const VPtrInfo & VBT,const CXXRecordDecl * RD,llvm::GlobalVariable::LinkageTypes Linkage)2060 MicrosoftCXXABI::getAddrOfVBTable(const VPtrInfo &VBT, const CXXRecordDecl *RD,
2061 llvm::GlobalVariable::LinkageTypes Linkage) {
2062 SmallString<256> OutName;
2063 llvm::raw_svector_ostream Out(OutName);
2064 getMangleContext().mangleCXXVBTable(RD, VBT.MangledPath, Out);
2065 StringRef Name = OutName.str();
2066
2067 llvm::ArrayType *VBTableType =
2068 llvm::ArrayType::get(CGM.IntTy, 1 + VBT.ObjectWithVPtr->getNumVBases());
2069
2070 assert(!CGM.getModule().getNamedGlobal(Name) &&
2071 "vbtable with this name already exists: mangling bug?");
2072 CharUnits Alignment =
2073 CGM.getContext().getTypeAlignInChars(CGM.getContext().IntTy);
2074 llvm::GlobalVariable *GV = CGM.CreateOrReplaceCXXRuntimeVariable(
2075 Name, VBTableType, Linkage, Alignment.getQuantity());
2076 GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
2077
2078 if (RD->hasAttr<DLLImportAttr>())
2079 GV->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass);
2080 else if (RD->hasAttr<DLLExportAttr>())
2081 GV->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);
2082
2083 if (!GV->hasExternalLinkage())
2084 emitVBTableDefinition(VBT, RD, GV);
2085
2086 return GV;
2087 }
2088
emitVBTableDefinition(const VPtrInfo & VBT,const CXXRecordDecl * RD,llvm::GlobalVariable * GV) const2089 void MicrosoftCXXABI::emitVBTableDefinition(const VPtrInfo &VBT,
2090 const CXXRecordDecl *RD,
2091 llvm::GlobalVariable *GV) const {
2092 const CXXRecordDecl *ObjectWithVPtr = VBT.ObjectWithVPtr;
2093
2094 assert(RD->getNumVBases() && ObjectWithVPtr->getNumVBases() &&
2095 "should only emit vbtables for classes with vbtables");
2096
2097 const ASTRecordLayout &BaseLayout =
2098 getContext().getASTRecordLayout(VBT.IntroducingObject);
2099 const ASTRecordLayout &DerivedLayout = getContext().getASTRecordLayout(RD);
2100
2101 SmallVector<llvm::Constant *, 4> Offsets(1 + ObjectWithVPtr->getNumVBases(),
2102 nullptr);
2103
2104 // The offset from ObjectWithVPtr's vbptr to itself always leads.
2105 CharUnits VBPtrOffset = BaseLayout.getVBPtrOffset();
2106 Offsets[0] = llvm::ConstantInt::get(CGM.IntTy, -VBPtrOffset.getQuantity());
2107
2108 MicrosoftVTableContext &Context = CGM.getMicrosoftVTableContext();
2109 for (const auto &I : ObjectWithVPtr->vbases()) {
2110 const CXXRecordDecl *VBase = I.getType()->getAsCXXRecordDecl();
2111 CharUnits Offset = DerivedLayout.getVBaseClassOffset(VBase);
2112 assert(!Offset.isNegative());
2113
2114 // Make it relative to the subobject vbptr.
2115 CharUnits CompleteVBPtrOffset = VBT.NonVirtualOffset + VBPtrOffset;
2116 if (VBT.getVBaseWithVPtr())
2117 CompleteVBPtrOffset +=
2118 DerivedLayout.getVBaseClassOffset(VBT.getVBaseWithVPtr());
2119 Offset -= CompleteVBPtrOffset;
2120
2121 unsigned VBIndex = Context.getVBTableIndex(ObjectWithVPtr, VBase);
2122 assert(Offsets[VBIndex] == nullptr && "The same vbindex seen twice?");
2123 Offsets[VBIndex] = llvm::ConstantInt::get(CGM.IntTy, Offset.getQuantity());
2124 }
2125
2126 assert(Offsets.size() ==
2127 cast<llvm::ArrayType>(cast<llvm::PointerType>(GV->getType())
2128 ->getElementType())->getNumElements());
2129 llvm::ArrayType *VBTableType =
2130 llvm::ArrayType::get(CGM.IntTy, Offsets.size());
2131 llvm::Constant *Init = llvm::ConstantArray::get(VBTableType, Offsets);
2132 GV->setInitializer(Init);
2133
2134 if (RD->hasAttr<DLLImportAttr>())
2135 GV->setLinkage(llvm::GlobalVariable::AvailableExternallyLinkage);
2136 }
2137
performThisAdjustment(CodeGenFunction & CGF,Address This,const ThisAdjustment & TA)2138 llvm::Value *MicrosoftCXXABI::performThisAdjustment(CodeGenFunction &CGF,
2139 Address This,
2140 const ThisAdjustment &TA) {
2141 if (TA.isEmpty())
2142 return This.getPointer();
2143
2144 This = CGF.Builder.CreateElementBitCast(This, CGF.Int8Ty);
2145
2146 llvm::Value *V;
2147 if (TA.Virtual.isEmpty()) {
2148 V = This.getPointer();
2149 } else {
2150 assert(TA.Virtual.Microsoft.VtordispOffset < 0);
2151 // Adjust the this argument based on the vtordisp value.
2152 Address VtorDispPtr =
2153 CGF.Builder.CreateConstInBoundsByteGEP(This,
2154 CharUnits::fromQuantity(TA.Virtual.Microsoft.VtordispOffset));
2155 VtorDispPtr = CGF.Builder.CreateElementBitCast(VtorDispPtr, CGF.Int32Ty);
2156 llvm::Value *VtorDisp = CGF.Builder.CreateLoad(VtorDispPtr, "vtordisp");
2157 V = CGF.Builder.CreateGEP(This.getPointer(),
2158 CGF.Builder.CreateNeg(VtorDisp));
2159
2160 // Unfortunately, having applied the vtordisp means that we no
2161 // longer really have a known alignment for the vbptr step.
2162 // We'll assume the vbptr is pointer-aligned.
2163
2164 if (TA.Virtual.Microsoft.VBPtrOffset) {
2165 // If the final overrider is defined in a virtual base other than the one
2166 // that holds the vfptr, we have to use a vtordispex thunk which looks up
2167 // the vbtable of the derived class.
2168 assert(TA.Virtual.Microsoft.VBPtrOffset > 0);
2169 assert(TA.Virtual.Microsoft.VBOffsetOffset >= 0);
2170 llvm::Value *VBPtr;
2171 llvm::Value *VBaseOffset =
2172 GetVBaseOffsetFromVBPtr(CGF, Address(V, CGF.getPointerAlign()),
2173 -TA.Virtual.Microsoft.VBPtrOffset,
2174 TA.Virtual.Microsoft.VBOffsetOffset, &VBPtr);
2175 V = CGF.Builder.CreateInBoundsGEP(VBPtr, VBaseOffset);
2176 }
2177 }
2178
2179 if (TA.NonVirtual) {
2180 // Non-virtual adjustment might result in a pointer outside the allocated
2181 // object, e.g. if the final overrider class is laid out after the virtual
2182 // base that declares a method in the most derived class.
2183 V = CGF.Builder.CreateConstGEP1_32(V, TA.NonVirtual);
2184 }
2185
2186 // Don't need to bitcast back, the call CodeGen will handle this.
2187 return V;
2188 }
2189
2190 llvm::Value *
performReturnAdjustment(CodeGenFunction & CGF,Address Ret,const ReturnAdjustment & RA)2191 MicrosoftCXXABI::performReturnAdjustment(CodeGenFunction &CGF, Address Ret,
2192 const ReturnAdjustment &RA) {
2193 if (RA.isEmpty())
2194 return Ret.getPointer();
2195
2196 auto OrigTy = Ret.getType();
2197 Ret = CGF.Builder.CreateElementBitCast(Ret, CGF.Int8Ty);
2198
2199 llvm::Value *V = Ret.getPointer();
2200 if (RA.Virtual.Microsoft.VBIndex) {
2201 assert(RA.Virtual.Microsoft.VBIndex > 0);
2202 int32_t IntSize = CGF.getIntSize().getQuantity();
2203 llvm::Value *VBPtr;
2204 llvm::Value *VBaseOffset =
2205 GetVBaseOffsetFromVBPtr(CGF, Ret, RA.Virtual.Microsoft.VBPtrOffset,
2206 IntSize * RA.Virtual.Microsoft.VBIndex, &VBPtr);
2207 V = CGF.Builder.CreateInBoundsGEP(VBPtr, VBaseOffset);
2208 }
2209
2210 if (RA.NonVirtual)
2211 V = CGF.Builder.CreateConstInBoundsGEP1_32(CGF.Int8Ty, V, RA.NonVirtual);
2212
2213 // Cast back to the original type.
2214 return CGF.Builder.CreateBitCast(V, OrigTy);
2215 }
2216
requiresArrayCookie(const CXXDeleteExpr * expr,QualType elementType)2217 bool MicrosoftCXXABI::requiresArrayCookie(const CXXDeleteExpr *expr,
2218 QualType elementType) {
2219 // Microsoft seems to completely ignore the possibility of a
2220 // two-argument usual deallocation function.
2221 return elementType.isDestructedType();
2222 }
2223
requiresArrayCookie(const CXXNewExpr * expr)2224 bool MicrosoftCXXABI::requiresArrayCookie(const CXXNewExpr *expr) {
2225 // Microsoft seems to completely ignore the possibility of a
2226 // two-argument usual deallocation function.
2227 return expr->getAllocatedType().isDestructedType();
2228 }
2229
getArrayCookieSizeImpl(QualType type)2230 CharUnits MicrosoftCXXABI::getArrayCookieSizeImpl(QualType type) {
2231 // The array cookie is always a size_t; we then pad that out to the
2232 // alignment of the element type.
2233 ASTContext &Ctx = getContext();
2234 return std::max(Ctx.getTypeSizeInChars(Ctx.getSizeType()),
2235 Ctx.getTypeAlignInChars(type));
2236 }
2237
readArrayCookieImpl(CodeGenFunction & CGF,Address allocPtr,CharUnits cookieSize)2238 llvm::Value *MicrosoftCXXABI::readArrayCookieImpl(CodeGenFunction &CGF,
2239 Address allocPtr,
2240 CharUnits cookieSize) {
2241 Address numElementsPtr =
2242 CGF.Builder.CreateElementBitCast(allocPtr, CGF.SizeTy);
2243 return CGF.Builder.CreateLoad(numElementsPtr);
2244 }
2245
InitializeArrayCookie(CodeGenFunction & CGF,Address newPtr,llvm::Value * numElements,const CXXNewExpr * expr,QualType elementType)2246 Address MicrosoftCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,
2247 Address newPtr,
2248 llvm::Value *numElements,
2249 const CXXNewExpr *expr,
2250 QualType elementType) {
2251 assert(requiresArrayCookie(expr));
2252
2253 // The size of the cookie.
2254 CharUnits cookieSize = getArrayCookieSizeImpl(elementType);
2255
2256 // Compute an offset to the cookie.
2257 Address cookiePtr = newPtr;
2258
2259 // Write the number of elements into the appropriate slot.
2260 Address numElementsPtr
2261 = CGF.Builder.CreateElementBitCast(cookiePtr, CGF.SizeTy);
2262 CGF.Builder.CreateStore(numElements, numElementsPtr);
2263
2264 // Finally, compute a pointer to the actual data buffer by skipping
2265 // over the cookie completely.
2266 return CGF.Builder.CreateConstInBoundsByteGEP(newPtr, cookieSize);
2267 }
2268
emitGlobalDtorWithTLRegDtor(CodeGenFunction & CGF,const VarDecl & VD,llvm::FunctionCallee Dtor,llvm::Constant * Addr)2269 static void emitGlobalDtorWithTLRegDtor(CodeGenFunction &CGF, const VarDecl &VD,
2270 llvm::FunctionCallee Dtor,
2271 llvm::Constant *Addr) {
2272 // Create a function which calls the destructor.
2273 llvm::Constant *DtorStub = CGF.createAtExitStub(VD, Dtor, Addr);
2274
2275 // extern "C" int __tlregdtor(void (*f)(void));
2276 llvm::FunctionType *TLRegDtorTy = llvm::FunctionType::get(
2277 CGF.IntTy, DtorStub->getType(), /*isVarArg=*/false);
2278
2279 llvm::FunctionCallee TLRegDtor = CGF.CGM.CreateRuntimeFunction(
2280 TLRegDtorTy, "__tlregdtor", llvm::AttributeList(), /*Local=*/true);
2281 if (llvm::Function *TLRegDtorFn =
2282 dyn_cast<llvm::Function>(TLRegDtor.getCallee()))
2283 TLRegDtorFn->setDoesNotThrow();
2284
2285 CGF.EmitNounwindRuntimeCall(TLRegDtor, DtorStub);
2286 }
2287
registerGlobalDtor(CodeGenFunction & CGF,const VarDecl & D,llvm::FunctionCallee Dtor,llvm::Constant * Addr)2288 void MicrosoftCXXABI::registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,
2289 llvm::FunctionCallee Dtor,
2290 llvm::Constant *Addr) {
2291 if (D.isNoDestroy(CGM.getContext()))
2292 return;
2293
2294 if (D.getTLSKind())
2295 return emitGlobalDtorWithTLRegDtor(CGF, D, Dtor, Addr);
2296
2297 // The default behavior is to use atexit.
2298 CGF.registerGlobalDtorWithAtExit(D, Dtor, Addr);
2299 }
2300
EmitThreadLocalInitFuncs(CodeGenModule & CGM,ArrayRef<const VarDecl * > CXXThreadLocals,ArrayRef<llvm::Function * > CXXThreadLocalInits,ArrayRef<const VarDecl * > CXXThreadLocalInitVars)2301 void MicrosoftCXXABI::EmitThreadLocalInitFuncs(
2302 CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals,
2303 ArrayRef<llvm::Function *> CXXThreadLocalInits,
2304 ArrayRef<const VarDecl *> CXXThreadLocalInitVars) {
2305 if (CXXThreadLocalInits.empty())
2306 return;
2307
2308 CGM.AppendLinkerOptions(CGM.getTarget().getTriple().getArch() ==
2309 llvm::Triple::x86
2310 ? "/include:___dyn_tls_init@12"
2311 : "/include:__dyn_tls_init");
2312
2313 // This will create a GV in the .CRT$XDU section. It will point to our
2314 // initialization function. The CRT will call all of these function
2315 // pointers at start-up time and, eventually, at thread-creation time.
2316 auto AddToXDU = [&CGM](llvm::Function *InitFunc) {
2317 llvm::GlobalVariable *InitFuncPtr = new llvm::GlobalVariable(
2318 CGM.getModule(), InitFunc->getType(), /*isConstant=*/true,
2319 llvm::GlobalVariable::InternalLinkage, InitFunc,
2320 Twine(InitFunc->getName(), "$initializer$"));
2321 InitFuncPtr->setSection(".CRT$XDU");
2322 // This variable has discardable linkage, we have to add it to @llvm.used to
2323 // ensure it won't get discarded.
2324 CGM.addUsedGlobal(InitFuncPtr);
2325 return InitFuncPtr;
2326 };
2327
2328 std::vector<llvm::Function *> NonComdatInits;
2329 for (size_t I = 0, E = CXXThreadLocalInitVars.size(); I != E; ++I) {
2330 llvm::GlobalVariable *GV = cast<llvm::GlobalVariable>(
2331 CGM.GetGlobalValue(CGM.getMangledName(CXXThreadLocalInitVars[I])));
2332 llvm::Function *F = CXXThreadLocalInits[I];
2333
2334 // If the GV is already in a comdat group, then we have to join it.
2335 if (llvm::Comdat *C = GV->getComdat())
2336 AddToXDU(F)->setComdat(C);
2337 else
2338 NonComdatInits.push_back(F);
2339 }
2340
2341 if (!NonComdatInits.empty()) {
2342 llvm::FunctionType *FTy =
2343 llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false);
2344 llvm::Function *InitFunc = CGM.CreateGlobalInitOrDestructFunction(
2345 FTy, "__tls_init", CGM.getTypes().arrangeNullaryFunction(),
2346 SourceLocation(), /*TLS=*/true);
2347 CodeGenFunction(CGM).GenerateCXXGlobalInitFunc(InitFunc, NonComdatInits);
2348
2349 AddToXDU(InitFunc);
2350 }
2351 }
2352
EmitThreadLocalVarDeclLValue(CodeGenFunction & CGF,const VarDecl * VD,QualType LValType)2353 LValue MicrosoftCXXABI::EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF,
2354 const VarDecl *VD,
2355 QualType LValType) {
2356 CGF.CGM.ErrorUnsupported(VD, "thread wrappers");
2357 return LValue();
2358 }
2359
getInitThreadEpochPtr(CodeGenModule & CGM)2360 static ConstantAddress getInitThreadEpochPtr(CodeGenModule &CGM) {
2361 StringRef VarName("_Init_thread_epoch");
2362 CharUnits Align = CGM.getIntAlign();
2363 if (auto *GV = CGM.getModule().getNamedGlobal(VarName))
2364 return ConstantAddress(GV, Align);
2365 auto *GV = new llvm::GlobalVariable(
2366 CGM.getModule(), CGM.IntTy,
2367 /*isConstant=*/false, llvm::GlobalVariable::ExternalLinkage,
2368 /*Initializer=*/nullptr, VarName,
2369 /*InsertBefore=*/nullptr, llvm::GlobalVariable::GeneralDynamicTLSModel);
2370 GV->setAlignment(Align.getAsAlign());
2371 return ConstantAddress(GV, Align);
2372 }
2373
getInitThreadHeaderFn(CodeGenModule & CGM)2374 static llvm::FunctionCallee getInitThreadHeaderFn(CodeGenModule &CGM) {
2375 llvm::FunctionType *FTy =
2376 llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()),
2377 CGM.IntTy->getPointerTo(), /*isVarArg=*/false);
2378 return CGM.CreateRuntimeFunction(
2379 FTy, "_Init_thread_header",
2380 llvm::AttributeList::get(CGM.getLLVMContext(),
2381 llvm::AttributeList::FunctionIndex,
2382 llvm::Attribute::NoUnwind),
2383 /*Local=*/true);
2384 }
2385
getInitThreadFooterFn(CodeGenModule & CGM)2386 static llvm::FunctionCallee getInitThreadFooterFn(CodeGenModule &CGM) {
2387 llvm::FunctionType *FTy =
2388 llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()),
2389 CGM.IntTy->getPointerTo(), /*isVarArg=*/false);
2390 return CGM.CreateRuntimeFunction(
2391 FTy, "_Init_thread_footer",
2392 llvm::AttributeList::get(CGM.getLLVMContext(),
2393 llvm::AttributeList::FunctionIndex,
2394 llvm::Attribute::NoUnwind),
2395 /*Local=*/true);
2396 }
2397
getInitThreadAbortFn(CodeGenModule & CGM)2398 static llvm::FunctionCallee getInitThreadAbortFn(CodeGenModule &CGM) {
2399 llvm::FunctionType *FTy =
2400 llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()),
2401 CGM.IntTy->getPointerTo(), /*isVarArg=*/false);
2402 return CGM.CreateRuntimeFunction(
2403 FTy, "_Init_thread_abort",
2404 llvm::AttributeList::get(CGM.getLLVMContext(),
2405 llvm::AttributeList::FunctionIndex,
2406 llvm::Attribute::NoUnwind),
2407 /*Local=*/true);
2408 }
2409
2410 namespace {
2411 struct ResetGuardBit final : EHScopeStack::Cleanup {
2412 Address Guard;
2413 unsigned GuardNum;
ResetGuardBit__anon4d9609fc0711::ResetGuardBit2414 ResetGuardBit(Address Guard, unsigned GuardNum)
2415 : Guard(Guard), GuardNum(GuardNum) {}
2416
Emit__anon4d9609fc0711::ResetGuardBit2417 void Emit(CodeGenFunction &CGF, Flags flags) override {
2418 // Reset the bit in the mask so that the static variable may be
2419 // reinitialized.
2420 CGBuilderTy &Builder = CGF.Builder;
2421 llvm::LoadInst *LI = Builder.CreateLoad(Guard);
2422 llvm::ConstantInt *Mask =
2423 llvm::ConstantInt::get(CGF.IntTy, ~(1ULL << GuardNum));
2424 Builder.CreateStore(Builder.CreateAnd(LI, Mask), Guard);
2425 }
2426 };
2427
2428 struct CallInitThreadAbort final : EHScopeStack::Cleanup {
2429 llvm::Value *Guard;
CallInitThreadAbort__anon4d9609fc0711::CallInitThreadAbort2430 CallInitThreadAbort(Address Guard) : Guard(Guard.getPointer()) {}
2431
Emit__anon4d9609fc0711::CallInitThreadAbort2432 void Emit(CodeGenFunction &CGF, Flags flags) override {
2433 // Calling _Init_thread_abort will reset the guard's state.
2434 CGF.EmitNounwindRuntimeCall(getInitThreadAbortFn(CGF.CGM), Guard);
2435 }
2436 };
2437 }
2438
EmitGuardedInit(CodeGenFunction & CGF,const VarDecl & D,llvm::GlobalVariable * GV,bool PerformInit)2439 void MicrosoftCXXABI::EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
2440 llvm::GlobalVariable *GV,
2441 bool PerformInit) {
2442 // MSVC only uses guards for static locals.
2443 if (!D.isStaticLocal()) {
2444 assert(GV->hasWeakLinkage() || GV->hasLinkOnceLinkage());
2445 // GlobalOpt is allowed to discard the initializer, so use linkonce_odr.
2446 llvm::Function *F = CGF.CurFn;
2447 F->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage);
2448 F->setComdat(CGM.getModule().getOrInsertComdat(F->getName()));
2449 CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit);
2450 return;
2451 }
2452
2453 bool ThreadlocalStatic = D.getTLSKind();
2454 bool ThreadsafeStatic = getContext().getLangOpts().ThreadsafeStatics;
2455
2456 // Thread-safe static variables which aren't thread-specific have a
2457 // per-variable guard.
2458 bool HasPerVariableGuard = ThreadsafeStatic && !ThreadlocalStatic;
2459
2460 CGBuilderTy &Builder = CGF.Builder;
2461 llvm::IntegerType *GuardTy = CGF.Int32Ty;
2462 llvm::ConstantInt *Zero = llvm::ConstantInt::get(GuardTy, 0);
2463 CharUnits GuardAlign = CharUnits::fromQuantity(4);
2464
2465 // Get the guard variable for this function if we have one already.
2466 GuardInfo *GI = nullptr;
2467 if (ThreadlocalStatic)
2468 GI = &ThreadLocalGuardVariableMap[D.getDeclContext()];
2469 else if (!ThreadsafeStatic)
2470 GI = &GuardVariableMap[D.getDeclContext()];
2471
2472 llvm::GlobalVariable *GuardVar = GI ? GI->Guard : nullptr;
2473 unsigned GuardNum;
2474 if (D.isExternallyVisible()) {
2475 // Externally visible variables have to be numbered in Sema to properly
2476 // handle unreachable VarDecls.
2477 GuardNum = getContext().getStaticLocalNumber(&D);
2478 assert(GuardNum > 0);
2479 GuardNum--;
2480 } else if (HasPerVariableGuard) {
2481 GuardNum = ThreadSafeGuardNumMap[D.getDeclContext()]++;
2482 } else {
2483 // Non-externally visible variables are numbered here in CodeGen.
2484 GuardNum = GI->BitIndex++;
2485 }
2486
2487 if (!HasPerVariableGuard && GuardNum >= 32) {
2488 if (D.isExternallyVisible())
2489 ErrorUnsupportedABI(CGF, "more than 32 guarded initializations");
2490 GuardNum %= 32;
2491 GuardVar = nullptr;
2492 }
2493
2494 if (!GuardVar) {
2495 // Mangle the name for the guard.
2496 SmallString<256> GuardName;
2497 {
2498 llvm::raw_svector_ostream Out(GuardName);
2499 if (HasPerVariableGuard)
2500 getMangleContext().mangleThreadSafeStaticGuardVariable(&D, GuardNum,
2501 Out);
2502 else
2503 getMangleContext().mangleStaticGuardVariable(&D, Out);
2504 }
2505
2506 // Create the guard variable with a zero-initializer. Just absorb linkage,
2507 // visibility and dll storage class from the guarded variable.
2508 GuardVar =
2509 new llvm::GlobalVariable(CGM.getModule(), GuardTy, /*isConstant=*/false,
2510 GV->getLinkage(), Zero, GuardName.str());
2511 GuardVar->setVisibility(GV->getVisibility());
2512 GuardVar->setDLLStorageClass(GV->getDLLStorageClass());
2513 GuardVar->setAlignment(GuardAlign.getAsAlign());
2514 if (GuardVar->isWeakForLinker())
2515 GuardVar->setComdat(
2516 CGM.getModule().getOrInsertComdat(GuardVar->getName()));
2517 if (D.getTLSKind())
2518 GuardVar->setThreadLocal(true);
2519 if (GI && !HasPerVariableGuard)
2520 GI->Guard = GuardVar;
2521 }
2522
2523 ConstantAddress GuardAddr(GuardVar, GuardAlign);
2524
2525 assert(GuardVar->getLinkage() == GV->getLinkage() &&
2526 "static local from the same function had different linkage");
2527
2528 if (!HasPerVariableGuard) {
2529 // Pseudo code for the test:
2530 // if (!(GuardVar & MyGuardBit)) {
2531 // GuardVar |= MyGuardBit;
2532 // ... initialize the object ...;
2533 // }
2534
2535 // Test our bit from the guard variable.
2536 llvm::ConstantInt *Bit = llvm::ConstantInt::get(GuardTy, 1ULL << GuardNum);
2537 llvm::LoadInst *LI = Builder.CreateLoad(GuardAddr);
2538 llvm::Value *NeedsInit =
2539 Builder.CreateICmpEQ(Builder.CreateAnd(LI, Bit), Zero);
2540 llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init");
2541 llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end");
2542 CGF.EmitCXXGuardedInitBranch(NeedsInit, InitBlock, EndBlock,
2543 CodeGenFunction::GuardKind::VariableGuard, &D);
2544
2545 // Set our bit in the guard variable and emit the initializer and add a global
2546 // destructor if appropriate.
2547 CGF.EmitBlock(InitBlock);
2548 Builder.CreateStore(Builder.CreateOr(LI, Bit), GuardAddr);
2549 CGF.EHStack.pushCleanup<ResetGuardBit>(EHCleanup, GuardAddr, GuardNum);
2550 CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit);
2551 CGF.PopCleanupBlock();
2552 Builder.CreateBr(EndBlock);
2553
2554 // Continue.
2555 CGF.EmitBlock(EndBlock);
2556 } else {
2557 // Pseudo code for the test:
2558 // if (TSS > _Init_thread_epoch) {
2559 // _Init_thread_header(&TSS);
2560 // if (TSS == -1) {
2561 // ... initialize the object ...;
2562 // _Init_thread_footer(&TSS);
2563 // }
2564 // }
2565 //
2566 // The algorithm is almost identical to what can be found in the appendix
2567 // found in N2325.
2568
2569 // This BasicBLock determines whether or not we have any work to do.
2570 llvm::LoadInst *FirstGuardLoad = Builder.CreateLoad(GuardAddr);
2571 FirstGuardLoad->setOrdering(llvm::AtomicOrdering::Unordered);
2572 llvm::LoadInst *InitThreadEpoch =
2573 Builder.CreateLoad(getInitThreadEpochPtr(CGM));
2574 llvm::Value *IsUninitialized =
2575 Builder.CreateICmpSGT(FirstGuardLoad, InitThreadEpoch);
2576 llvm::BasicBlock *AttemptInitBlock = CGF.createBasicBlock("init.attempt");
2577 llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end");
2578 CGF.EmitCXXGuardedInitBranch(IsUninitialized, AttemptInitBlock, EndBlock,
2579 CodeGenFunction::GuardKind::VariableGuard, &D);
2580
2581 // This BasicBlock attempts to determine whether or not this thread is
2582 // responsible for doing the initialization.
2583 CGF.EmitBlock(AttemptInitBlock);
2584 CGF.EmitNounwindRuntimeCall(getInitThreadHeaderFn(CGM),
2585 GuardAddr.getPointer());
2586 llvm::LoadInst *SecondGuardLoad = Builder.CreateLoad(GuardAddr);
2587 SecondGuardLoad->setOrdering(llvm::AtomicOrdering::Unordered);
2588 llvm::Value *ShouldDoInit =
2589 Builder.CreateICmpEQ(SecondGuardLoad, getAllOnesInt());
2590 llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init");
2591 Builder.CreateCondBr(ShouldDoInit, InitBlock, EndBlock);
2592
2593 // Ok, we ended up getting selected as the initializing thread.
2594 CGF.EmitBlock(InitBlock);
2595 CGF.EHStack.pushCleanup<CallInitThreadAbort>(EHCleanup, GuardAddr);
2596 CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit);
2597 CGF.PopCleanupBlock();
2598 CGF.EmitNounwindRuntimeCall(getInitThreadFooterFn(CGM),
2599 GuardAddr.getPointer());
2600 Builder.CreateBr(EndBlock);
2601
2602 CGF.EmitBlock(EndBlock);
2603 }
2604 }
2605
isZeroInitializable(const MemberPointerType * MPT)2606 bool MicrosoftCXXABI::isZeroInitializable(const MemberPointerType *MPT) {
2607 // Null-ness for function memptrs only depends on the first field, which is
2608 // the function pointer. The rest don't matter, so we can zero initialize.
2609 if (MPT->isMemberFunctionPointer())
2610 return true;
2611
2612 // The virtual base adjustment field is always -1 for null, so if we have one
2613 // we can't zero initialize. The field offset is sometimes also -1 if 0 is a
2614 // valid field offset.
2615 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
2616 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2617 return (!inheritanceModelHasVBTableOffsetField(Inheritance) &&
2618 RD->nullFieldOffsetIsZero());
2619 }
2620
2621 llvm::Type *
ConvertMemberPointerType(const MemberPointerType * MPT)2622 MicrosoftCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) {
2623 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
2624 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2625 llvm::SmallVector<llvm::Type *, 4> fields;
2626 if (MPT->isMemberFunctionPointer())
2627 fields.push_back(CGM.VoidPtrTy); // FunctionPointerOrVirtualThunk
2628 else
2629 fields.push_back(CGM.IntTy); // FieldOffset
2630
2631 if (inheritanceModelHasNVOffsetField(MPT->isMemberFunctionPointer(),
2632 Inheritance))
2633 fields.push_back(CGM.IntTy);
2634 if (inheritanceModelHasVBPtrOffsetField(Inheritance))
2635 fields.push_back(CGM.IntTy);
2636 if (inheritanceModelHasVBTableOffsetField(Inheritance))
2637 fields.push_back(CGM.IntTy); // VirtualBaseAdjustmentOffset
2638
2639 if (fields.size() == 1)
2640 return fields[0];
2641 return llvm::StructType::get(CGM.getLLVMContext(), fields);
2642 }
2643
2644 void MicrosoftCXXABI::
GetNullMemberPointerFields(const MemberPointerType * MPT,llvm::SmallVectorImpl<llvm::Constant * > & fields)2645 GetNullMemberPointerFields(const MemberPointerType *MPT,
2646 llvm::SmallVectorImpl<llvm::Constant *> &fields) {
2647 assert(fields.empty());
2648 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
2649 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2650 if (MPT->isMemberFunctionPointer()) {
2651 // FunctionPointerOrVirtualThunk
2652 fields.push_back(llvm::Constant::getNullValue(CGM.VoidPtrTy));
2653 } else {
2654 if (RD->nullFieldOffsetIsZero())
2655 fields.push_back(getZeroInt()); // FieldOffset
2656 else
2657 fields.push_back(getAllOnesInt()); // FieldOffset
2658 }
2659
2660 if (inheritanceModelHasNVOffsetField(MPT->isMemberFunctionPointer(),
2661 Inheritance))
2662 fields.push_back(getZeroInt());
2663 if (inheritanceModelHasVBPtrOffsetField(Inheritance))
2664 fields.push_back(getZeroInt());
2665 if (inheritanceModelHasVBTableOffsetField(Inheritance))
2666 fields.push_back(getAllOnesInt());
2667 }
2668
2669 llvm::Constant *
EmitNullMemberPointer(const MemberPointerType * MPT)2670 MicrosoftCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) {
2671 llvm::SmallVector<llvm::Constant *, 4> fields;
2672 GetNullMemberPointerFields(MPT, fields);
2673 if (fields.size() == 1)
2674 return fields[0];
2675 llvm::Constant *Res = llvm::ConstantStruct::getAnon(fields);
2676 assert(Res->getType() == ConvertMemberPointerType(MPT));
2677 return Res;
2678 }
2679
2680 llvm::Constant *
EmitFullMemberPointer(llvm::Constant * FirstField,bool IsMemberFunction,const CXXRecordDecl * RD,CharUnits NonVirtualBaseAdjustment,unsigned VBTableIndex)2681 MicrosoftCXXABI::EmitFullMemberPointer(llvm::Constant *FirstField,
2682 bool IsMemberFunction,
2683 const CXXRecordDecl *RD,
2684 CharUnits NonVirtualBaseAdjustment,
2685 unsigned VBTableIndex) {
2686 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2687
2688 // Single inheritance class member pointer are represented as scalars instead
2689 // of aggregates.
2690 if (inheritanceModelHasOnlyOneField(IsMemberFunction, Inheritance))
2691 return FirstField;
2692
2693 llvm::SmallVector<llvm::Constant *, 4> fields;
2694 fields.push_back(FirstField);
2695
2696 if (inheritanceModelHasNVOffsetField(IsMemberFunction, Inheritance))
2697 fields.push_back(llvm::ConstantInt::get(
2698 CGM.IntTy, NonVirtualBaseAdjustment.getQuantity()));
2699
2700 if (inheritanceModelHasVBPtrOffsetField(Inheritance)) {
2701 CharUnits Offs = CharUnits::Zero();
2702 if (VBTableIndex)
2703 Offs = getContext().getASTRecordLayout(RD).getVBPtrOffset();
2704 fields.push_back(llvm::ConstantInt::get(CGM.IntTy, Offs.getQuantity()));
2705 }
2706
2707 // The rest of the fields are adjusted by conversions to a more derived class.
2708 if (inheritanceModelHasVBTableOffsetField(Inheritance))
2709 fields.push_back(llvm::ConstantInt::get(CGM.IntTy, VBTableIndex));
2710
2711 return llvm::ConstantStruct::getAnon(fields);
2712 }
2713
2714 llvm::Constant *
EmitMemberDataPointer(const MemberPointerType * MPT,CharUnits offset)2715 MicrosoftCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT,
2716 CharUnits offset) {
2717 return EmitMemberDataPointer(MPT->getMostRecentCXXRecordDecl(), offset);
2718 }
2719
EmitMemberDataPointer(const CXXRecordDecl * RD,CharUnits offset)2720 llvm::Constant *MicrosoftCXXABI::EmitMemberDataPointer(const CXXRecordDecl *RD,
2721 CharUnits offset) {
2722 if (RD->getMSInheritanceModel() ==
2723 MSInheritanceModel::Virtual)
2724 offset -= getContext().getOffsetOfBaseWithVBPtr(RD);
2725 llvm::Constant *FirstField =
2726 llvm::ConstantInt::get(CGM.IntTy, offset.getQuantity());
2727 return EmitFullMemberPointer(FirstField, /*IsMemberFunction=*/false, RD,
2728 CharUnits::Zero(), /*VBTableIndex=*/0);
2729 }
2730
EmitMemberPointer(const APValue & MP,QualType MPType)2731 llvm::Constant *MicrosoftCXXABI::EmitMemberPointer(const APValue &MP,
2732 QualType MPType) {
2733 const MemberPointerType *DstTy = MPType->castAs<MemberPointerType>();
2734 const ValueDecl *MPD = MP.getMemberPointerDecl();
2735 if (!MPD)
2736 return EmitNullMemberPointer(DstTy);
2737
2738 ASTContext &Ctx = getContext();
2739 ArrayRef<const CXXRecordDecl *> MemberPointerPath = MP.getMemberPointerPath();
2740
2741 llvm::Constant *C;
2742 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MPD)) {
2743 C = EmitMemberFunctionPointer(MD);
2744 } else {
2745 // For a pointer to data member, start off with the offset of the field in
2746 // the class in which it was declared, and convert from there if necessary.
2747 // For indirect field decls, get the outermost anonymous field and use the
2748 // parent class.
2749 CharUnits FieldOffset = Ctx.toCharUnitsFromBits(Ctx.getFieldOffset(MPD));
2750 const FieldDecl *FD = dyn_cast<FieldDecl>(MPD);
2751 if (!FD)
2752 FD = cast<FieldDecl>(*cast<IndirectFieldDecl>(MPD)->chain_begin());
2753 const CXXRecordDecl *RD = cast<CXXRecordDecl>(FD->getParent());
2754 RD = RD->getMostRecentNonInjectedDecl();
2755 C = EmitMemberDataPointer(RD, FieldOffset);
2756 }
2757
2758 if (!MemberPointerPath.empty()) {
2759 const CXXRecordDecl *SrcRD = cast<CXXRecordDecl>(MPD->getDeclContext());
2760 const Type *SrcRecTy = Ctx.getTypeDeclType(SrcRD).getTypePtr();
2761 const MemberPointerType *SrcTy =
2762 Ctx.getMemberPointerType(DstTy->getPointeeType(), SrcRecTy)
2763 ->castAs<MemberPointerType>();
2764
2765 bool DerivedMember = MP.isMemberPointerToDerivedMember();
2766 SmallVector<const CXXBaseSpecifier *, 4> DerivedToBasePath;
2767 const CXXRecordDecl *PrevRD = SrcRD;
2768 for (const CXXRecordDecl *PathElem : MemberPointerPath) {
2769 const CXXRecordDecl *Base = nullptr;
2770 const CXXRecordDecl *Derived = nullptr;
2771 if (DerivedMember) {
2772 Base = PathElem;
2773 Derived = PrevRD;
2774 } else {
2775 Base = PrevRD;
2776 Derived = PathElem;
2777 }
2778 for (const CXXBaseSpecifier &BS : Derived->bases())
2779 if (BS.getType()->getAsCXXRecordDecl()->getCanonicalDecl() ==
2780 Base->getCanonicalDecl())
2781 DerivedToBasePath.push_back(&BS);
2782 PrevRD = PathElem;
2783 }
2784 assert(DerivedToBasePath.size() == MemberPointerPath.size());
2785
2786 CastKind CK = DerivedMember ? CK_DerivedToBaseMemberPointer
2787 : CK_BaseToDerivedMemberPointer;
2788 C = EmitMemberPointerConversion(SrcTy, DstTy, CK, DerivedToBasePath.begin(),
2789 DerivedToBasePath.end(), C);
2790 }
2791 return C;
2792 }
2793
2794 llvm::Constant *
EmitMemberFunctionPointer(const CXXMethodDecl * MD)2795 MicrosoftCXXABI::EmitMemberFunctionPointer(const CXXMethodDecl *MD) {
2796 assert(MD->isInstance() && "Member function must not be static!");
2797
2798 CharUnits NonVirtualBaseAdjustment = CharUnits::Zero();
2799 const CXXRecordDecl *RD = MD->getParent()->getMostRecentNonInjectedDecl();
2800 CodeGenTypes &Types = CGM.getTypes();
2801
2802 unsigned VBTableIndex = 0;
2803 llvm::Constant *FirstField;
2804 const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>();
2805 if (!MD->isVirtual()) {
2806 llvm::Type *Ty;
2807 // Check whether the function has a computable LLVM signature.
2808 if (Types.isFuncTypeConvertible(FPT)) {
2809 // The function has a computable LLVM signature; use the correct type.
2810 Ty = Types.GetFunctionType(Types.arrangeCXXMethodDeclaration(MD));
2811 } else {
2812 // Use an arbitrary non-function type to tell GetAddrOfFunction that the
2813 // function type is incomplete.
2814 Ty = CGM.PtrDiffTy;
2815 }
2816 FirstField = CGM.GetAddrOfFunction(MD, Ty);
2817 } else {
2818 auto &VTableContext = CGM.getMicrosoftVTableContext();
2819 MethodVFTableLocation ML = VTableContext.getMethodVFTableLocation(MD);
2820 FirstField = EmitVirtualMemPtrThunk(MD, ML);
2821 // Include the vfptr adjustment if the method is in a non-primary vftable.
2822 NonVirtualBaseAdjustment += ML.VFPtrOffset;
2823 if (ML.VBase)
2824 VBTableIndex = VTableContext.getVBTableIndex(RD, ML.VBase) * 4;
2825 }
2826
2827 if (VBTableIndex == 0 &&
2828 RD->getMSInheritanceModel() ==
2829 MSInheritanceModel::Virtual)
2830 NonVirtualBaseAdjustment -= getContext().getOffsetOfBaseWithVBPtr(RD);
2831
2832 // The rest of the fields are common with data member pointers.
2833 FirstField = llvm::ConstantExpr::getBitCast(FirstField, CGM.VoidPtrTy);
2834 return EmitFullMemberPointer(FirstField, /*IsMemberFunction=*/true, RD,
2835 NonVirtualBaseAdjustment, VBTableIndex);
2836 }
2837
2838 /// Member pointers are the same if they're either bitwise identical *or* both
2839 /// null. Null-ness for function members is determined by the first field,
2840 /// while for data member pointers we must compare all fields.
2841 llvm::Value *
EmitMemberPointerComparison(CodeGenFunction & CGF,llvm::Value * L,llvm::Value * R,const MemberPointerType * MPT,bool Inequality)2842 MicrosoftCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF,
2843 llvm::Value *L,
2844 llvm::Value *R,
2845 const MemberPointerType *MPT,
2846 bool Inequality) {
2847 CGBuilderTy &Builder = CGF.Builder;
2848
2849 // Handle != comparisons by switching the sense of all boolean operations.
2850 llvm::ICmpInst::Predicate Eq;
2851 llvm::Instruction::BinaryOps And, Or;
2852 if (Inequality) {
2853 Eq = llvm::ICmpInst::ICMP_NE;
2854 And = llvm::Instruction::Or;
2855 Or = llvm::Instruction::And;
2856 } else {
2857 Eq = llvm::ICmpInst::ICMP_EQ;
2858 And = llvm::Instruction::And;
2859 Or = llvm::Instruction::Or;
2860 }
2861
2862 // If this is a single field member pointer (single inheritance), this is a
2863 // single icmp.
2864 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
2865 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2866 if (inheritanceModelHasOnlyOneField(MPT->isMemberFunctionPointer(),
2867 Inheritance))
2868 return Builder.CreateICmp(Eq, L, R);
2869
2870 // Compare the first field.
2871 llvm::Value *L0 = Builder.CreateExtractValue(L, 0, "lhs.0");
2872 llvm::Value *R0 = Builder.CreateExtractValue(R, 0, "rhs.0");
2873 llvm::Value *Cmp0 = Builder.CreateICmp(Eq, L0, R0, "memptr.cmp.first");
2874
2875 // Compare everything other than the first field.
2876 llvm::Value *Res = nullptr;
2877 llvm::StructType *LType = cast<llvm::StructType>(L->getType());
2878 for (unsigned I = 1, E = LType->getNumElements(); I != E; ++I) {
2879 llvm::Value *LF = Builder.CreateExtractValue(L, I);
2880 llvm::Value *RF = Builder.CreateExtractValue(R, I);
2881 llvm::Value *Cmp = Builder.CreateICmp(Eq, LF, RF, "memptr.cmp.rest");
2882 if (Res)
2883 Res = Builder.CreateBinOp(And, Res, Cmp);
2884 else
2885 Res = Cmp;
2886 }
2887
2888 // Check if the first field is 0 if this is a function pointer.
2889 if (MPT->isMemberFunctionPointer()) {
2890 // (l1 == r1 && ...) || l0 == 0
2891 llvm::Value *Zero = llvm::Constant::getNullValue(L0->getType());
2892 llvm::Value *IsZero = Builder.CreateICmp(Eq, L0, Zero, "memptr.cmp.iszero");
2893 Res = Builder.CreateBinOp(Or, Res, IsZero);
2894 }
2895
2896 // Combine the comparison of the first field, which must always be true for
2897 // this comparison to succeeed.
2898 return Builder.CreateBinOp(And, Res, Cmp0, "memptr.cmp");
2899 }
2900
2901 llvm::Value *
EmitMemberPointerIsNotNull(CodeGenFunction & CGF,llvm::Value * MemPtr,const MemberPointerType * MPT)2902 MicrosoftCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
2903 llvm::Value *MemPtr,
2904 const MemberPointerType *MPT) {
2905 CGBuilderTy &Builder = CGF.Builder;
2906 llvm::SmallVector<llvm::Constant *, 4> fields;
2907 // We only need one field for member functions.
2908 if (MPT->isMemberFunctionPointer())
2909 fields.push_back(llvm::Constant::getNullValue(CGM.VoidPtrTy));
2910 else
2911 GetNullMemberPointerFields(MPT, fields);
2912 assert(!fields.empty());
2913 llvm::Value *FirstField = MemPtr;
2914 if (MemPtr->getType()->isStructTy())
2915 FirstField = Builder.CreateExtractValue(MemPtr, 0);
2916 llvm::Value *Res = Builder.CreateICmpNE(FirstField, fields[0], "memptr.cmp0");
2917
2918 // For function member pointers, we only need to test the function pointer
2919 // field. The other fields if any can be garbage.
2920 if (MPT->isMemberFunctionPointer())
2921 return Res;
2922
2923 // Otherwise, emit a series of compares and combine the results.
2924 for (int I = 1, E = fields.size(); I < E; ++I) {
2925 llvm::Value *Field = Builder.CreateExtractValue(MemPtr, I);
2926 llvm::Value *Next = Builder.CreateICmpNE(Field, fields[I], "memptr.cmp");
2927 Res = Builder.CreateOr(Res, Next, "memptr.tobool");
2928 }
2929 return Res;
2930 }
2931
MemberPointerConstantIsNull(const MemberPointerType * MPT,llvm::Constant * Val)2932 bool MicrosoftCXXABI::MemberPointerConstantIsNull(const MemberPointerType *MPT,
2933 llvm::Constant *Val) {
2934 // Function pointers are null if the pointer in the first field is null.
2935 if (MPT->isMemberFunctionPointer()) {
2936 llvm::Constant *FirstField = Val->getType()->isStructTy() ?
2937 Val->getAggregateElement(0U) : Val;
2938 return FirstField->isNullValue();
2939 }
2940
2941 // If it's not a function pointer and it's zero initializable, we can easily
2942 // check zero.
2943 if (isZeroInitializable(MPT) && Val->isNullValue())
2944 return true;
2945
2946 // Otherwise, break down all the fields for comparison. Hopefully these
2947 // little Constants are reused, while a big null struct might not be.
2948 llvm::SmallVector<llvm::Constant *, 4> Fields;
2949 GetNullMemberPointerFields(MPT, Fields);
2950 if (Fields.size() == 1) {
2951 assert(Val->getType()->isIntegerTy());
2952 return Val == Fields[0];
2953 }
2954
2955 unsigned I, E;
2956 for (I = 0, E = Fields.size(); I != E; ++I) {
2957 if (Val->getAggregateElement(I) != Fields[I])
2958 break;
2959 }
2960 return I == E;
2961 }
2962
2963 llvm::Value *
GetVBaseOffsetFromVBPtr(CodeGenFunction & CGF,Address This,llvm::Value * VBPtrOffset,llvm::Value * VBTableOffset,llvm::Value ** VBPtrOut)2964 MicrosoftCXXABI::GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,
2965 Address This,
2966 llvm::Value *VBPtrOffset,
2967 llvm::Value *VBTableOffset,
2968 llvm::Value **VBPtrOut) {
2969 CGBuilderTy &Builder = CGF.Builder;
2970 // Load the vbtable pointer from the vbptr in the instance.
2971 This = Builder.CreateElementBitCast(This, CGM.Int8Ty);
2972 llvm::Value *VBPtr =
2973 Builder.CreateInBoundsGEP(This.getPointer(), VBPtrOffset, "vbptr");
2974 if (VBPtrOut) *VBPtrOut = VBPtr;
2975 VBPtr = Builder.CreateBitCast(VBPtr,
2976 CGM.Int32Ty->getPointerTo(0)->getPointerTo(This.getAddressSpace()));
2977
2978 CharUnits VBPtrAlign;
2979 if (auto CI = dyn_cast<llvm::ConstantInt>(VBPtrOffset)) {
2980 VBPtrAlign = This.getAlignment().alignmentAtOffset(
2981 CharUnits::fromQuantity(CI->getSExtValue()));
2982 } else {
2983 VBPtrAlign = CGF.getPointerAlign();
2984 }
2985
2986 llvm::Value *VBTable = Builder.CreateAlignedLoad(VBPtr, VBPtrAlign, "vbtable");
2987
2988 // Translate from byte offset to table index. It improves analyzability.
2989 llvm::Value *VBTableIndex = Builder.CreateAShr(
2990 VBTableOffset, llvm::ConstantInt::get(VBTableOffset->getType(), 2),
2991 "vbtindex", /*isExact=*/true);
2992
2993 // Load an i32 offset from the vb-table.
2994 llvm::Value *VBaseOffs = Builder.CreateInBoundsGEP(VBTable, VBTableIndex);
2995 VBaseOffs = Builder.CreateBitCast(VBaseOffs, CGM.Int32Ty->getPointerTo(0));
2996 return Builder.CreateAlignedLoad(VBaseOffs, CharUnits::fromQuantity(4),
2997 "vbase_offs");
2998 }
2999
3000 // Returns an adjusted base cast to i8*, since we do more address arithmetic on
3001 // it.
AdjustVirtualBase(CodeGenFunction & CGF,const Expr * E,const CXXRecordDecl * RD,Address Base,llvm::Value * VBTableOffset,llvm::Value * VBPtrOffset)3002 llvm::Value *MicrosoftCXXABI::AdjustVirtualBase(
3003 CodeGenFunction &CGF, const Expr *E, const CXXRecordDecl *RD,
3004 Address Base, llvm::Value *VBTableOffset, llvm::Value *VBPtrOffset) {
3005 CGBuilderTy &Builder = CGF.Builder;
3006 Base = Builder.CreateElementBitCast(Base, CGM.Int8Ty);
3007 llvm::BasicBlock *OriginalBB = nullptr;
3008 llvm::BasicBlock *SkipAdjustBB = nullptr;
3009 llvm::BasicBlock *VBaseAdjustBB = nullptr;
3010
3011 // In the unspecified inheritance model, there might not be a vbtable at all,
3012 // in which case we need to skip the virtual base lookup. If there is a
3013 // vbtable, the first entry is a no-op entry that gives back the original
3014 // base, so look for a virtual base adjustment offset of zero.
3015 if (VBPtrOffset) {
3016 OriginalBB = Builder.GetInsertBlock();
3017 VBaseAdjustBB = CGF.createBasicBlock("memptr.vadjust");
3018 SkipAdjustBB = CGF.createBasicBlock("memptr.skip_vadjust");
3019 llvm::Value *IsVirtual =
3020 Builder.CreateICmpNE(VBTableOffset, getZeroInt(),
3021 "memptr.is_vbase");
3022 Builder.CreateCondBr(IsVirtual, VBaseAdjustBB, SkipAdjustBB);
3023 CGF.EmitBlock(VBaseAdjustBB);
3024 }
3025
3026 // If we weren't given a dynamic vbptr offset, RD should be complete and we'll
3027 // know the vbptr offset.
3028 if (!VBPtrOffset) {
3029 CharUnits offs = CharUnits::Zero();
3030 if (!RD->hasDefinition()) {
3031 DiagnosticsEngine &Diags = CGF.CGM.getDiags();
3032 unsigned DiagID = Diags.getCustomDiagID(
3033 DiagnosticsEngine::Error,
3034 "member pointer representation requires a "
3035 "complete class type for %0 to perform this expression");
3036 Diags.Report(E->getExprLoc(), DiagID) << RD << E->getSourceRange();
3037 } else if (RD->getNumVBases())
3038 offs = getContext().getASTRecordLayout(RD).getVBPtrOffset();
3039 VBPtrOffset = llvm::ConstantInt::get(CGM.IntTy, offs.getQuantity());
3040 }
3041 llvm::Value *VBPtr = nullptr;
3042 llvm::Value *VBaseOffs =
3043 GetVBaseOffsetFromVBPtr(CGF, Base, VBPtrOffset, VBTableOffset, &VBPtr);
3044 llvm::Value *AdjustedBase = Builder.CreateInBoundsGEP(VBPtr, VBaseOffs);
3045
3046 // Merge control flow with the case where we didn't have to adjust.
3047 if (VBaseAdjustBB) {
3048 Builder.CreateBr(SkipAdjustBB);
3049 CGF.EmitBlock(SkipAdjustBB);
3050 llvm::PHINode *Phi = Builder.CreatePHI(CGM.Int8PtrTy, 2, "memptr.base");
3051 Phi->addIncoming(Base.getPointer(), OriginalBB);
3052 Phi->addIncoming(AdjustedBase, VBaseAdjustBB);
3053 return Phi;
3054 }
3055 return AdjustedBase;
3056 }
3057
EmitMemberDataPointerAddress(CodeGenFunction & CGF,const Expr * E,Address Base,llvm::Value * MemPtr,const MemberPointerType * MPT)3058 llvm::Value *MicrosoftCXXABI::EmitMemberDataPointerAddress(
3059 CodeGenFunction &CGF, const Expr *E, Address Base, llvm::Value *MemPtr,
3060 const MemberPointerType *MPT) {
3061 assert(MPT->isMemberDataPointer());
3062 unsigned AS = Base.getAddressSpace();
3063 llvm::Type *PType =
3064 CGF.ConvertTypeForMem(MPT->getPointeeType())->getPointerTo(AS);
3065 CGBuilderTy &Builder = CGF.Builder;
3066 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
3067 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
3068
3069 // Extract the fields we need, regardless of model. We'll apply them if we
3070 // have them.
3071 llvm::Value *FieldOffset = MemPtr;
3072 llvm::Value *VirtualBaseAdjustmentOffset = nullptr;
3073 llvm::Value *VBPtrOffset = nullptr;
3074 if (MemPtr->getType()->isStructTy()) {
3075 // We need to extract values.
3076 unsigned I = 0;
3077 FieldOffset = Builder.CreateExtractValue(MemPtr, I++);
3078 if (inheritanceModelHasVBPtrOffsetField(Inheritance))
3079 VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++);
3080 if (inheritanceModelHasVBTableOffsetField(Inheritance))
3081 VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++);
3082 }
3083
3084 llvm::Value *Addr;
3085 if (VirtualBaseAdjustmentOffset) {
3086 Addr = AdjustVirtualBase(CGF, E, RD, Base, VirtualBaseAdjustmentOffset,
3087 VBPtrOffset);
3088 } else {
3089 Addr = Base.getPointer();
3090 }
3091
3092 // Cast to char*.
3093 Addr = Builder.CreateBitCast(Addr, CGF.Int8Ty->getPointerTo(AS));
3094
3095 // Apply the offset, which we assume is non-null.
3096 Addr = Builder.CreateInBoundsGEP(Addr, FieldOffset, "memptr.offset");
3097
3098 // Cast the address to the appropriate pointer type, adopting the address
3099 // space of the base pointer.
3100 return Builder.CreateBitCast(Addr, PType);
3101 }
3102
3103 llvm::Value *
EmitMemberPointerConversion(CodeGenFunction & CGF,const CastExpr * E,llvm::Value * Src)3104 MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
3105 const CastExpr *E,
3106 llvm::Value *Src) {
3107 assert(E->getCastKind() == CK_DerivedToBaseMemberPointer ||
3108 E->getCastKind() == CK_BaseToDerivedMemberPointer ||
3109 E->getCastKind() == CK_ReinterpretMemberPointer);
3110
3111 // Use constant emission if we can.
3112 if (isa<llvm::Constant>(Src))
3113 return EmitMemberPointerConversion(E, cast<llvm::Constant>(Src));
3114
3115 // We may be adding or dropping fields from the member pointer, so we need
3116 // both types and the inheritance models of both records.
3117 const MemberPointerType *SrcTy =
3118 E->getSubExpr()->getType()->castAs<MemberPointerType>();
3119 const MemberPointerType *DstTy = E->getType()->castAs<MemberPointerType>();
3120 bool IsFunc = SrcTy->isMemberFunctionPointer();
3121
3122 // If the classes use the same null representation, reinterpret_cast is a nop.
3123 bool IsReinterpret = E->getCastKind() == CK_ReinterpretMemberPointer;
3124 if (IsReinterpret && IsFunc)
3125 return Src;
3126
3127 CXXRecordDecl *SrcRD = SrcTy->getMostRecentCXXRecordDecl();
3128 CXXRecordDecl *DstRD = DstTy->getMostRecentCXXRecordDecl();
3129 if (IsReinterpret &&
3130 SrcRD->nullFieldOffsetIsZero() == DstRD->nullFieldOffsetIsZero())
3131 return Src;
3132
3133 CGBuilderTy &Builder = CGF.Builder;
3134
3135 // Branch past the conversion if Src is null.
3136 llvm::Value *IsNotNull = EmitMemberPointerIsNotNull(CGF, Src, SrcTy);
3137 llvm::Constant *DstNull = EmitNullMemberPointer(DstTy);
3138
3139 // C++ 5.2.10p9: The null member pointer value is converted to the null member
3140 // pointer value of the destination type.
3141 if (IsReinterpret) {
3142 // For reinterpret casts, sema ensures that src and dst are both functions
3143 // or data and have the same size, which means the LLVM types should match.
3144 assert(Src->getType() == DstNull->getType());
3145 return Builder.CreateSelect(IsNotNull, Src, DstNull);
3146 }
3147
3148 llvm::BasicBlock *OriginalBB = Builder.GetInsertBlock();
3149 llvm::BasicBlock *ConvertBB = CGF.createBasicBlock("memptr.convert");
3150 llvm::BasicBlock *ContinueBB = CGF.createBasicBlock("memptr.converted");
3151 Builder.CreateCondBr(IsNotNull, ConvertBB, ContinueBB);
3152 CGF.EmitBlock(ConvertBB);
3153
3154 llvm::Value *Dst = EmitNonNullMemberPointerConversion(
3155 SrcTy, DstTy, E->getCastKind(), E->path_begin(), E->path_end(), Src,
3156 Builder);
3157
3158 Builder.CreateBr(ContinueBB);
3159
3160 // In the continuation, choose between DstNull and Dst.
3161 CGF.EmitBlock(ContinueBB);
3162 llvm::PHINode *Phi = Builder.CreatePHI(DstNull->getType(), 2, "memptr.converted");
3163 Phi->addIncoming(DstNull, OriginalBB);
3164 Phi->addIncoming(Dst, ConvertBB);
3165 return Phi;
3166 }
3167
EmitNonNullMemberPointerConversion(const MemberPointerType * SrcTy,const MemberPointerType * DstTy,CastKind CK,CastExpr::path_const_iterator PathBegin,CastExpr::path_const_iterator PathEnd,llvm::Value * Src,CGBuilderTy & Builder)3168 llvm::Value *MicrosoftCXXABI::EmitNonNullMemberPointerConversion(
3169 const MemberPointerType *SrcTy, const MemberPointerType *DstTy, CastKind CK,
3170 CastExpr::path_const_iterator PathBegin,
3171 CastExpr::path_const_iterator PathEnd, llvm::Value *Src,
3172 CGBuilderTy &Builder) {
3173 const CXXRecordDecl *SrcRD = SrcTy->getMostRecentCXXRecordDecl();
3174 const CXXRecordDecl *DstRD = DstTy->getMostRecentCXXRecordDecl();
3175 MSInheritanceModel SrcInheritance = SrcRD->getMSInheritanceModel();
3176 MSInheritanceModel DstInheritance = DstRD->getMSInheritanceModel();
3177 bool IsFunc = SrcTy->isMemberFunctionPointer();
3178 bool IsConstant = isa<llvm::Constant>(Src);
3179
3180 // Decompose src.
3181 llvm::Value *FirstField = Src;
3182 llvm::Value *NonVirtualBaseAdjustment = getZeroInt();
3183 llvm::Value *VirtualBaseAdjustmentOffset = getZeroInt();
3184 llvm::Value *VBPtrOffset = getZeroInt();
3185 if (!inheritanceModelHasOnlyOneField(IsFunc, SrcInheritance)) {
3186 // We need to extract values.
3187 unsigned I = 0;
3188 FirstField = Builder.CreateExtractValue(Src, I++);
3189 if (inheritanceModelHasNVOffsetField(IsFunc, SrcInheritance))
3190 NonVirtualBaseAdjustment = Builder.CreateExtractValue(Src, I++);
3191 if (inheritanceModelHasVBPtrOffsetField(SrcInheritance))
3192 VBPtrOffset = Builder.CreateExtractValue(Src, I++);
3193 if (inheritanceModelHasVBTableOffsetField(SrcInheritance))
3194 VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(Src, I++);
3195 }
3196
3197 bool IsDerivedToBase = (CK == CK_DerivedToBaseMemberPointer);
3198 const MemberPointerType *DerivedTy = IsDerivedToBase ? SrcTy : DstTy;
3199 const CXXRecordDecl *DerivedClass = DerivedTy->getMostRecentCXXRecordDecl();
3200
3201 // For data pointers, we adjust the field offset directly. For functions, we
3202 // have a separate field.
3203 llvm::Value *&NVAdjustField = IsFunc ? NonVirtualBaseAdjustment : FirstField;
3204
3205 // The virtual inheritance model has a quirk: the virtual base table is always
3206 // referenced when dereferencing a member pointer even if the member pointer
3207 // is non-virtual. This is accounted for by adjusting the non-virtual offset
3208 // to point backwards to the top of the MDC from the first VBase. Undo this
3209 // adjustment to normalize the member pointer.
3210 llvm::Value *SrcVBIndexEqZero =
3211 Builder.CreateICmpEQ(VirtualBaseAdjustmentOffset, getZeroInt());
3212 if (SrcInheritance == MSInheritanceModel::Virtual) {
3213 if (int64_t SrcOffsetToFirstVBase =
3214 getContext().getOffsetOfBaseWithVBPtr(SrcRD).getQuantity()) {
3215 llvm::Value *UndoSrcAdjustment = Builder.CreateSelect(
3216 SrcVBIndexEqZero,
3217 llvm::ConstantInt::get(CGM.IntTy, SrcOffsetToFirstVBase),
3218 getZeroInt());
3219 NVAdjustField = Builder.CreateNSWAdd(NVAdjustField, UndoSrcAdjustment);
3220 }
3221 }
3222
3223 // A non-zero vbindex implies that we are dealing with a source member in a
3224 // floating virtual base in addition to some non-virtual offset. If the
3225 // vbindex is zero, we are dealing with a source that exists in a non-virtual,
3226 // fixed, base. The difference between these two cases is that the vbindex +
3227 // nvoffset *always* point to the member regardless of what context they are
3228 // evaluated in so long as the vbindex is adjusted. A member inside a fixed
3229 // base requires explicit nv adjustment.
3230 llvm::Constant *BaseClassOffset = llvm::ConstantInt::get(
3231 CGM.IntTy,
3232 CGM.computeNonVirtualBaseClassOffset(DerivedClass, PathBegin, PathEnd)
3233 .getQuantity());
3234
3235 llvm::Value *NVDisp;
3236 if (IsDerivedToBase)
3237 NVDisp = Builder.CreateNSWSub(NVAdjustField, BaseClassOffset, "adj");
3238 else
3239 NVDisp = Builder.CreateNSWAdd(NVAdjustField, BaseClassOffset, "adj");
3240
3241 NVAdjustField = Builder.CreateSelect(SrcVBIndexEqZero, NVDisp, getZeroInt());
3242
3243 // Update the vbindex to an appropriate value in the destination because
3244 // SrcRD's vbtable might not be a strict prefix of the one in DstRD.
3245 llvm::Value *DstVBIndexEqZero = SrcVBIndexEqZero;
3246 if (inheritanceModelHasVBTableOffsetField(DstInheritance) &&
3247 inheritanceModelHasVBTableOffsetField(SrcInheritance)) {
3248 if (llvm::GlobalVariable *VDispMap =
3249 getAddrOfVirtualDisplacementMap(SrcRD, DstRD)) {
3250 llvm::Value *VBIndex = Builder.CreateExactUDiv(
3251 VirtualBaseAdjustmentOffset, llvm::ConstantInt::get(CGM.IntTy, 4));
3252 if (IsConstant) {
3253 llvm::Constant *Mapping = VDispMap->getInitializer();
3254 VirtualBaseAdjustmentOffset =
3255 Mapping->getAggregateElement(cast<llvm::Constant>(VBIndex));
3256 } else {
3257 llvm::Value *Idxs[] = {getZeroInt(), VBIndex};
3258 VirtualBaseAdjustmentOffset =
3259 Builder.CreateAlignedLoad(Builder.CreateInBoundsGEP(VDispMap, Idxs),
3260 CharUnits::fromQuantity(4));
3261 }
3262
3263 DstVBIndexEqZero =
3264 Builder.CreateICmpEQ(VirtualBaseAdjustmentOffset, getZeroInt());
3265 }
3266 }
3267
3268 // Set the VBPtrOffset to zero if the vbindex is zero. Otherwise, initialize
3269 // it to the offset of the vbptr.
3270 if (inheritanceModelHasVBPtrOffsetField(DstInheritance)) {
3271 llvm::Value *DstVBPtrOffset = llvm::ConstantInt::get(
3272 CGM.IntTy,
3273 getContext().getASTRecordLayout(DstRD).getVBPtrOffset().getQuantity());
3274 VBPtrOffset =
3275 Builder.CreateSelect(DstVBIndexEqZero, getZeroInt(), DstVBPtrOffset);
3276 }
3277
3278 // Likewise, apply a similar adjustment so that dereferencing the member
3279 // pointer correctly accounts for the distance between the start of the first
3280 // virtual base and the top of the MDC.
3281 if (DstInheritance == MSInheritanceModel::Virtual) {
3282 if (int64_t DstOffsetToFirstVBase =
3283 getContext().getOffsetOfBaseWithVBPtr(DstRD).getQuantity()) {
3284 llvm::Value *DoDstAdjustment = Builder.CreateSelect(
3285 DstVBIndexEqZero,
3286 llvm::ConstantInt::get(CGM.IntTy, DstOffsetToFirstVBase),
3287 getZeroInt());
3288 NVAdjustField = Builder.CreateNSWSub(NVAdjustField, DoDstAdjustment);
3289 }
3290 }
3291
3292 // Recompose dst from the null struct and the adjusted fields from src.
3293 llvm::Value *Dst;
3294 if (inheritanceModelHasOnlyOneField(IsFunc, DstInheritance)) {
3295 Dst = FirstField;
3296 } else {
3297 Dst = llvm::UndefValue::get(ConvertMemberPointerType(DstTy));
3298 unsigned Idx = 0;
3299 Dst = Builder.CreateInsertValue(Dst, FirstField, Idx++);
3300 if (inheritanceModelHasNVOffsetField(IsFunc, DstInheritance))
3301 Dst = Builder.CreateInsertValue(Dst, NonVirtualBaseAdjustment, Idx++);
3302 if (inheritanceModelHasVBPtrOffsetField(DstInheritance))
3303 Dst = Builder.CreateInsertValue(Dst, VBPtrOffset, Idx++);
3304 if (inheritanceModelHasVBTableOffsetField(DstInheritance))
3305 Dst = Builder.CreateInsertValue(Dst, VirtualBaseAdjustmentOffset, Idx++);
3306 }
3307 return Dst;
3308 }
3309
3310 llvm::Constant *
EmitMemberPointerConversion(const CastExpr * E,llvm::Constant * Src)3311 MicrosoftCXXABI::EmitMemberPointerConversion(const CastExpr *E,
3312 llvm::Constant *Src) {
3313 const MemberPointerType *SrcTy =
3314 E->getSubExpr()->getType()->castAs<MemberPointerType>();
3315 const MemberPointerType *DstTy = E->getType()->castAs<MemberPointerType>();
3316
3317 CastKind CK = E->getCastKind();
3318
3319 return EmitMemberPointerConversion(SrcTy, DstTy, CK, E->path_begin(),
3320 E->path_end(), Src);
3321 }
3322
EmitMemberPointerConversion(const MemberPointerType * SrcTy,const MemberPointerType * DstTy,CastKind CK,CastExpr::path_const_iterator PathBegin,CastExpr::path_const_iterator PathEnd,llvm::Constant * Src)3323 llvm::Constant *MicrosoftCXXABI::EmitMemberPointerConversion(
3324 const MemberPointerType *SrcTy, const MemberPointerType *DstTy, CastKind CK,
3325 CastExpr::path_const_iterator PathBegin,
3326 CastExpr::path_const_iterator PathEnd, llvm::Constant *Src) {
3327 assert(CK == CK_DerivedToBaseMemberPointer ||
3328 CK == CK_BaseToDerivedMemberPointer ||
3329 CK == CK_ReinterpretMemberPointer);
3330 // If src is null, emit a new null for dst. We can't return src because dst
3331 // might have a new representation.
3332 if (MemberPointerConstantIsNull(SrcTy, Src))
3333 return EmitNullMemberPointer(DstTy);
3334
3335 // We don't need to do anything for reinterpret_casts of non-null member
3336 // pointers. We should only get here when the two type representations have
3337 // the same size.
3338 if (CK == CK_ReinterpretMemberPointer)
3339 return Src;
3340
3341 CGBuilderTy Builder(CGM, CGM.getLLVMContext());
3342 auto *Dst = cast<llvm::Constant>(EmitNonNullMemberPointerConversion(
3343 SrcTy, DstTy, CK, PathBegin, PathEnd, Src, Builder));
3344
3345 return Dst;
3346 }
3347
EmitLoadOfMemberFunctionPointer(CodeGenFunction & CGF,const Expr * E,Address This,llvm::Value * & ThisPtrForCall,llvm::Value * MemPtr,const MemberPointerType * MPT)3348 CGCallee MicrosoftCXXABI::EmitLoadOfMemberFunctionPointer(
3349 CodeGenFunction &CGF, const Expr *E, Address This,
3350 llvm::Value *&ThisPtrForCall, llvm::Value *MemPtr,
3351 const MemberPointerType *MPT) {
3352 assert(MPT->isMemberFunctionPointer());
3353 const FunctionProtoType *FPT =
3354 MPT->getPointeeType()->castAs<FunctionProtoType>();
3355 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
3356 llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(
3357 CGM.getTypes().arrangeCXXMethodType(RD, FPT, /*FD=*/nullptr));
3358 CGBuilderTy &Builder = CGF.Builder;
3359
3360 MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
3361
3362 // Extract the fields we need, regardless of model. We'll apply them if we
3363 // have them.
3364 llvm::Value *FunctionPointer = MemPtr;
3365 llvm::Value *NonVirtualBaseAdjustment = nullptr;
3366 llvm::Value *VirtualBaseAdjustmentOffset = nullptr;
3367 llvm::Value *VBPtrOffset = nullptr;
3368 if (MemPtr->getType()->isStructTy()) {
3369 // We need to extract values.
3370 unsigned I = 0;
3371 FunctionPointer = Builder.CreateExtractValue(MemPtr, I++);
3372 if (inheritanceModelHasNVOffsetField(MPT, Inheritance))
3373 NonVirtualBaseAdjustment = Builder.CreateExtractValue(MemPtr, I++);
3374 if (inheritanceModelHasVBPtrOffsetField(Inheritance))
3375 VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++);
3376 if (inheritanceModelHasVBTableOffsetField(Inheritance))
3377 VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++);
3378 }
3379
3380 if (VirtualBaseAdjustmentOffset) {
3381 ThisPtrForCall = AdjustVirtualBase(CGF, E, RD, This,
3382 VirtualBaseAdjustmentOffset, VBPtrOffset);
3383 } else {
3384 ThisPtrForCall = This.getPointer();
3385 }
3386
3387 if (NonVirtualBaseAdjustment) {
3388 // Apply the adjustment and cast back to the original struct type.
3389 llvm::Value *Ptr = Builder.CreateBitCast(ThisPtrForCall, CGF.Int8PtrTy);
3390 Ptr = Builder.CreateInBoundsGEP(Ptr, NonVirtualBaseAdjustment);
3391 ThisPtrForCall = Builder.CreateBitCast(Ptr, ThisPtrForCall->getType(),
3392 "this.adjusted");
3393 }
3394
3395 FunctionPointer =
3396 Builder.CreateBitCast(FunctionPointer, FTy->getPointerTo());
3397 CGCallee Callee(FPT, FunctionPointer);
3398 return Callee;
3399 }
3400
CreateMicrosoftCXXABI(CodeGenModule & CGM)3401 CGCXXABI *clang::CodeGen::CreateMicrosoftCXXABI(CodeGenModule &CGM) {
3402 return new MicrosoftCXXABI(CGM);
3403 }
3404
3405 // MS RTTI Overview:
3406 // The run time type information emitted by cl.exe contains 5 distinct types of
3407 // structures. Many of them reference each other.
3408 //
3409 // TypeInfo: Static classes that are returned by typeid.
3410 //
3411 // CompleteObjectLocator: Referenced by vftables. They contain information
3412 // required for dynamic casting, including OffsetFromTop. They also contain
3413 // a reference to the TypeInfo for the type and a reference to the
3414 // CompleteHierarchyDescriptor for the type.
3415 //
3416 // ClassHierarchyDescriptor: Contains information about a class hierarchy.
3417 // Used during dynamic_cast to walk a class hierarchy. References a base
3418 // class array and the size of said array.
3419 //
3420 // BaseClassArray: Contains a list of classes in a hierarchy. BaseClassArray is
3421 // somewhat of a misnomer because the most derived class is also in the list
3422 // as well as multiple copies of virtual bases (if they occur multiple times
3423 // in the hierarchy.) The BaseClassArray contains one BaseClassDescriptor for
3424 // every path in the hierarchy, in pre-order depth first order. Note, we do
3425 // not declare a specific llvm type for BaseClassArray, it's merely an array
3426 // of BaseClassDescriptor pointers.
3427 //
3428 // BaseClassDescriptor: Contains information about a class in a class hierarchy.
3429 // BaseClassDescriptor is also somewhat of a misnomer for the same reason that
3430 // BaseClassArray is. It contains information about a class within a
3431 // hierarchy such as: is this base is ambiguous and what is its offset in the
3432 // vbtable. The names of the BaseClassDescriptors have all of their fields
3433 // mangled into them so they can be aggressively deduplicated by the linker.
3434
getTypeInfoVTable(CodeGenModule & CGM)3435 static llvm::GlobalVariable *getTypeInfoVTable(CodeGenModule &CGM) {
3436 StringRef MangledName("??_7type_info@@6B@");
3437 if (auto VTable = CGM.getModule().getNamedGlobal(MangledName))
3438 return VTable;
3439 return new llvm::GlobalVariable(CGM.getModule(), CGM.Int8PtrTy,
3440 /*isConstant=*/true,
3441 llvm::GlobalVariable::ExternalLinkage,
3442 /*Initializer=*/nullptr, MangledName);
3443 }
3444
3445 namespace {
3446
3447 /// A Helper struct that stores information about a class in a class
3448 /// hierarchy. The information stored in these structs struct is used during
3449 /// the generation of ClassHierarchyDescriptors and BaseClassDescriptors.
3450 // During RTTI creation, MSRTTIClasses are stored in a contiguous array with
3451 // implicit depth first pre-order tree connectivity. getFirstChild and
3452 // getNextSibling allow us to walk the tree efficiently.
3453 struct MSRTTIClass {
3454 enum {
3455 IsPrivateOnPath = 1 | 8,
3456 IsAmbiguous = 2,
3457 IsPrivate = 4,
3458 IsVirtual = 16,
3459 HasHierarchyDescriptor = 64
3460 };
MSRTTIClass__anon4d9609fc0811::MSRTTIClass3461 MSRTTIClass(const CXXRecordDecl *RD) : RD(RD) {}
3462 uint32_t initialize(const MSRTTIClass *Parent,
3463 const CXXBaseSpecifier *Specifier);
3464
getFirstChild__anon4d9609fc0811::MSRTTIClass3465 MSRTTIClass *getFirstChild() { return this + 1; }
getNextChild__anon4d9609fc0811::MSRTTIClass3466 static MSRTTIClass *getNextChild(MSRTTIClass *Child) {
3467 return Child + 1 + Child->NumBases;
3468 }
3469
3470 const CXXRecordDecl *RD, *VirtualRoot;
3471 uint32_t Flags, NumBases, OffsetInVBase;
3472 };
3473
3474 /// Recursively initialize the base class array.
initialize(const MSRTTIClass * Parent,const CXXBaseSpecifier * Specifier)3475 uint32_t MSRTTIClass::initialize(const MSRTTIClass *Parent,
3476 const CXXBaseSpecifier *Specifier) {
3477 Flags = HasHierarchyDescriptor;
3478 if (!Parent) {
3479 VirtualRoot = nullptr;
3480 OffsetInVBase = 0;
3481 } else {
3482 if (Specifier->getAccessSpecifier() != AS_public)
3483 Flags |= IsPrivate | IsPrivateOnPath;
3484 if (Specifier->isVirtual()) {
3485 Flags |= IsVirtual;
3486 VirtualRoot = RD;
3487 OffsetInVBase = 0;
3488 } else {
3489 if (Parent->Flags & IsPrivateOnPath)
3490 Flags |= IsPrivateOnPath;
3491 VirtualRoot = Parent->VirtualRoot;
3492 OffsetInVBase = Parent->OffsetInVBase + RD->getASTContext()
3493 .getASTRecordLayout(Parent->RD).getBaseClassOffset(RD).getQuantity();
3494 }
3495 }
3496 NumBases = 0;
3497 MSRTTIClass *Child = getFirstChild();
3498 for (const CXXBaseSpecifier &Base : RD->bases()) {
3499 NumBases += Child->initialize(this, &Base) + 1;
3500 Child = getNextChild(Child);
3501 }
3502 return NumBases;
3503 }
3504
getLinkageForRTTI(QualType Ty)3505 static llvm::GlobalValue::LinkageTypes getLinkageForRTTI(QualType Ty) {
3506 switch (Ty->getLinkage()) {
3507 case NoLinkage:
3508 case InternalLinkage:
3509 case UniqueExternalLinkage:
3510 return llvm::GlobalValue::InternalLinkage;
3511
3512 case VisibleNoLinkage:
3513 case ModuleInternalLinkage:
3514 case ModuleLinkage:
3515 case ExternalLinkage:
3516 return llvm::GlobalValue::LinkOnceODRLinkage;
3517 }
3518 llvm_unreachable("Invalid linkage!");
3519 }
3520
3521 /// An ephemeral helper class for building MS RTTI types. It caches some
3522 /// calls to the module and information about the most derived class in a
3523 /// hierarchy.
3524 struct MSRTTIBuilder {
3525 enum {
3526 HasBranchingHierarchy = 1,
3527 HasVirtualBranchingHierarchy = 2,
3528 HasAmbiguousBases = 4
3529 };
3530
MSRTTIBuilder__anon4d9609fc0811::MSRTTIBuilder3531 MSRTTIBuilder(MicrosoftCXXABI &ABI, const CXXRecordDecl *RD)
3532 : CGM(ABI.CGM), Context(CGM.getContext()),
3533 VMContext(CGM.getLLVMContext()), Module(CGM.getModule()), RD(RD),
3534 Linkage(getLinkageForRTTI(CGM.getContext().getTagDeclType(RD))),
3535 ABI(ABI) {}
3536
3537 llvm::GlobalVariable *getBaseClassDescriptor(const MSRTTIClass &Classes);
3538 llvm::GlobalVariable *
3539 getBaseClassArray(SmallVectorImpl<MSRTTIClass> &Classes);
3540 llvm::GlobalVariable *getClassHierarchyDescriptor();
3541 llvm::GlobalVariable *getCompleteObjectLocator(const VPtrInfo &Info);
3542
3543 CodeGenModule &CGM;
3544 ASTContext &Context;
3545 llvm::LLVMContext &VMContext;
3546 llvm::Module &Module;
3547 const CXXRecordDecl *RD;
3548 llvm::GlobalVariable::LinkageTypes Linkage;
3549 MicrosoftCXXABI &ABI;
3550 };
3551
3552 } // namespace
3553
3554 /// Recursively serializes a class hierarchy in pre-order depth first
3555 /// order.
serializeClassHierarchy(SmallVectorImpl<MSRTTIClass> & Classes,const CXXRecordDecl * RD)3556 static void serializeClassHierarchy(SmallVectorImpl<MSRTTIClass> &Classes,
3557 const CXXRecordDecl *RD) {
3558 Classes.push_back(MSRTTIClass(RD));
3559 for (const CXXBaseSpecifier &Base : RD->bases())
3560 serializeClassHierarchy(Classes, Base.getType()->getAsCXXRecordDecl());
3561 }
3562
3563 /// Find ambiguity among base classes.
3564 static void
detectAmbiguousBases(SmallVectorImpl<MSRTTIClass> & Classes)3565 detectAmbiguousBases(SmallVectorImpl<MSRTTIClass> &Classes) {
3566 llvm::SmallPtrSet<const CXXRecordDecl *, 8> VirtualBases;
3567 llvm::SmallPtrSet<const CXXRecordDecl *, 8> UniqueBases;
3568 llvm::SmallPtrSet<const CXXRecordDecl *, 8> AmbiguousBases;
3569 for (MSRTTIClass *Class = &Classes.front(); Class <= &Classes.back();) {
3570 if ((Class->Flags & MSRTTIClass::IsVirtual) &&
3571 !VirtualBases.insert(Class->RD).second) {
3572 Class = MSRTTIClass::getNextChild(Class);
3573 continue;
3574 }
3575 if (!UniqueBases.insert(Class->RD).second)
3576 AmbiguousBases.insert(Class->RD);
3577 Class++;
3578 }
3579 if (AmbiguousBases.empty())
3580 return;
3581 for (MSRTTIClass &Class : Classes)
3582 if (AmbiguousBases.count(Class.RD))
3583 Class.Flags |= MSRTTIClass::IsAmbiguous;
3584 }
3585
getClassHierarchyDescriptor()3586 llvm::GlobalVariable *MSRTTIBuilder::getClassHierarchyDescriptor() {
3587 SmallString<256> MangledName;
3588 {
3589 llvm::raw_svector_ostream Out(MangledName);
3590 ABI.getMangleContext().mangleCXXRTTIClassHierarchyDescriptor(RD, Out);
3591 }
3592
3593 // Check to see if we've already declared this ClassHierarchyDescriptor.
3594 if (auto CHD = Module.getNamedGlobal(MangledName))
3595 return CHD;
3596
3597 // Serialize the class hierarchy and initialize the CHD Fields.
3598 SmallVector<MSRTTIClass, 8> Classes;
3599 serializeClassHierarchy(Classes, RD);
3600 Classes.front().initialize(/*Parent=*/nullptr, /*Specifier=*/nullptr);
3601 detectAmbiguousBases(Classes);
3602 int Flags = 0;
3603 for (auto Class : Classes) {
3604 if (Class.RD->getNumBases() > 1)
3605 Flags |= HasBranchingHierarchy;
3606 // Note: cl.exe does not calculate "HasAmbiguousBases" correctly. We
3607 // believe the field isn't actually used.
3608 if (Class.Flags & MSRTTIClass::IsAmbiguous)
3609 Flags |= HasAmbiguousBases;
3610 }
3611 if ((Flags & HasBranchingHierarchy) && RD->getNumVBases() != 0)
3612 Flags |= HasVirtualBranchingHierarchy;
3613 // These gep indices are used to get the address of the first element of the
3614 // base class array.
3615 llvm::Value *GEPIndices[] = {llvm::ConstantInt::get(CGM.IntTy, 0),
3616 llvm::ConstantInt::get(CGM.IntTy, 0)};
3617
3618 // Forward-declare the class hierarchy descriptor
3619 auto Type = ABI.getClassHierarchyDescriptorType();
3620 auto CHD = new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage,
3621 /*Initializer=*/nullptr,
3622 MangledName);
3623 if (CHD->isWeakForLinker())
3624 CHD->setComdat(CGM.getModule().getOrInsertComdat(CHD->getName()));
3625
3626 auto *Bases = getBaseClassArray(Classes);
3627
3628 // Initialize the base class ClassHierarchyDescriptor.
3629 llvm::Constant *Fields[] = {
3630 llvm::ConstantInt::get(CGM.IntTy, 0), // reserved by the runtime
3631 llvm::ConstantInt::get(CGM.IntTy, Flags),
3632 llvm::ConstantInt::get(CGM.IntTy, Classes.size()),
3633 ABI.getImageRelativeConstant(llvm::ConstantExpr::getInBoundsGetElementPtr(
3634 Bases->getValueType(), Bases,
3635 llvm::ArrayRef<llvm::Value *>(GEPIndices))),
3636 };
3637 CHD->setInitializer(llvm::ConstantStruct::get(Type, Fields));
3638 return CHD;
3639 }
3640
3641 llvm::GlobalVariable *
getBaseClassArray(SmallVectorImpl<MSRTTIClass> & Classes)3642 MSRTTIBuilder::getBaseClassArray(SmallVectorImpl<MSRTTIClass> &Classes) {
3643 SmallString<256> MangledName;
3644 {
3645 llvm::raw_svector_ostream Out(MangledName);
3646 ABI.getMangleContext().mangleCXXRTTIBaseClassArray(RD, Out);
3647 }
3648
3649 // Forward-declare the base class array.
3650 // cl.exe pads the base class array with 1 (in 32 bit mode) or 4 (in 64 bit
3651 // mode) bytes of padding. We provide a pointer sized amount of padding by
3652 // adding +1 to Classes.size(). The sections have pointer alignment and are
3653 // marked pick-any so it shouldn't matter.
3654 llvm::Type *PtrType = ABI.getImageRelativeType(
3655 ABI.getBaseClassDescriptorType()->getPointerTo());
3656 auto *ArrType = llvm::ArrayType::get(PtrType, Classes.size() + 1);
3657 auto *BCA =
3658 new llvm::GlobalVariable(Module, ArrType,
3659 /*isConstant=*/true, Linkage,
3660 /*Initializer=*/nullptr, MangledName);
3661 if (BCA->isWeakForLinker())
3662 BCA->setComdat(CGM.getModule().getOrInsertComdat(BCA->getName()));
3663
3664 // Initialize the BaseClassArray.
3665 SmallVector<llvm::Constant *, 8> BaseClassArrayData;
3666 for (MSRTTIClass &Class : Classes)
3667 BaseClassArrayData.push_back(
3668 ABI.getImageRelativeConstant(getBaseClassDescriptor(Class)));
3669 BaseClassArrayData.push_back(llvm::Constant::getNullValue(PtrType));
3670 BCA->setInitializer(llvm::ConstantArray::get(ArrType, BaseClassArrayData));
3671 return BCA;
3672 }
3673
3674 llvm::GlobalVariable *
getBaseClassDescriptor(const MSRTTIClass & Class)3675 MSRTTIBuilder::getBaseClassDescriptor(const MSRTTIClass &Class) {
3676 // Compute the fields for the BaseClassDescriptor. They are computed up front
3677 // because they are mangled into the name of the object.
3678 uint32_t OffsetInVBTable = 0;
3679 int32_t VBPtrOffset = -1;
3680 if (Class.VirtualRoot) {
3681 auto &VTableContext = CGM.getMicrosoftVTableContext();
3682 OffsetInVBTable = VTableContext.getVBTableIndex(RD, Class.VirtualRoot) * 4;
3683 VBPtrOffset = Context.getASTRecordLayout(RD).getVBPtrOffset().getQuantity();
3684 }
3685
3686 SmallString<256> MangledName;
3687 {
3688 llvm::raw_svector_ostream Out(MangledName);
3689 ABI.getMangleContext().mangleCXXRTTIBaseClassDescriptor(
3690 Class.RD, Class.OffsetInVBase, VBPtrOffset, OffsetInVBTable,
3691 Class.Flags, Out);
3692 }
3693
3694 // Check to see if we've already declared this object.
3695 if (auto BCD = Module.getNamedGlobal(MangledName))
3696 return BCD;
3697
3698 // Forward-declare the base class descriptor.
3699 auto Type = ABI.getBaseClassDescriptorType();
3700 auto BCD =
3701 new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage,
3702 /*Initializer=*/nullptr, MangledName);
3703 if (BCD->isWeakForLinker())
3704 BCD->setComdat(CGM.getModule().getOrInsertComdat(BCD->getName()));
3705
3706 // Initialize the BaseClassDescriptor.
3707 llvm::Constant *Fields[] = {
3708 ABI.getImageRelativeConstant(
3709 ABI.getAddrOfRTTIDescriptor(Context.getTypeDeclType(Class.RD))),
3710 llvm::ConstantInt::get(CGM.IntTy, Class.NumBases),
3711 llvm::ConstantInt::get(CGM.IntTy, Class.OffsetInVBase),
3712 llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset),
3713 llvm::ConstantInt::get(CGM.IntTy, OffsetInVBTable),
3714 llvm::ConstantInt::get(CGM.IntTy, Class.Flags),
3715 ABI.getImageRelativeConstant(
3716 MSRTTIBuilder(ABI, Class.RD).getClassHierarchyDescriptor()),
3717 };
3718 BCD->setInitializer(llvm::ConstantStruct::get(Type, Fields));
3719 return BCD;
3720 }
3721
3722 llvm::GlobalVariable *
getCompleteObjectLocator(const VPtrInfo & Info)3723 MSRTTIBuilder::getCompleteObjectLocator(const VPtrInfo &Info) {
3724 SmallString<256> MangledName;
3725 {
3726 llvm::raw_svector_ostream Out(MangledName);
3727 ABI.getMangleContext().mangleCXXRTTICompleteObjectLocator(RD, Info.MangledPath, Out);
3728 }
3729
3730 // Check to see if we've already computed this complete object locator.
3731 if (auto COL = Module.getNamedGlobal(MangledName))
3732 return COL;
3733
3734 // Compute the fields of the complete object locator.
3735 int OffsetToTop = Info.FullOffsetInMDC.getQuantity();
3736 int VFPtrOffset = 0;
3737 // The offset includes the vtordisp if one exists.
3738 if (const CXXRecordDecl *VBase = Info.getVBaseWithVPtr())
3739 if (Context.getASTRecordLayout(RD)
3740 .getVBaseOffsetsMap()
3741 .find(VBase)
3742 ->second.hasVtorDisp())
3743 VFPtrOffset = Info.NonVirtualOffset.getQuantity() + 4;
3744
3745 // Forward-declare the complete object locator.
3746 llvm::StructType *Type = ABI.getCompleteObjectLocatorType();
3747 auto COL = new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage,
3748 /*Initializer=*/nullptr, MangledName);
3749
3750 // Initialize the CompleteObjectLocator.
3751 llvm::Constant *Fields[] = {
3752 llvm::ConstantInt::get(CGM.IntTy, ABI.isImageRelative()),
3753 llvm::ConstantInt::get(CGM.IntTy, OffsetToTop),
3754 llvm::ConstantInt::get(CGM.IntTy, VFPtrOffset),
3755 ABI.getImageRelativeConstant(
3756 CGM.GetAddrOfRTTIDescriptor(Context.getTypeDeclType(RD))),
3757 ABI.getImageRelativeConstant(getClassHierarchyDescriptor()),
3758 ABI.getImageRelativeConstant(COL),
3759 };
3760 llvm::ArrayRef<llvm::Constant *> FieldsRef(Fields);
3761 if (!ABI.isImageRelative())
3762 FieldsRef = FieldsRef.drop_back();
3763 COL->setInitializer(llvm::ConstantStruct::get(Type, FieldsRef));
3764 if (COL->isWeakForLinker())
3765 COL->setComdat(CGM.getModule().getOrInsertComdat(COL->getName()));
3766 return COL;
3767 }
3768
decomposeTypeForEH(ASTContext & Context,QualType T,bool & IsConst,bool & IsVolatile,bool & IsUnaligned)3769 static QualType decomposeTypeForEH(ASTContext &Context, QualType T,
3770 bool &IsConst, bool &IsVolatile,
3771 bool &IsUnaligned) {
3772 T = Context.getExceptionObjectType(T);
3773
3774 // C++14 [except.handle]p3:
3775 // A handler is a match for an exception object of type E if [...]
3776 // - the handler is of type cv T or const T& where T is a pointer type and
3777 // E is a pointer type that can be converted to T by [...]
3778 // - a qualification conversion
3779 IsConst = false;
3780 IsVolatile = false;
3781 IsUnaligned = false;
3782 QualType PointeeType = T->getPointeeType();
3783 if (!PointeeType.isNull()) {
3784 IsConst = PointeeType.isConstQualified();
3785 IsVolatile = PointeeType.isVolatileQualified();
3786 IsUnaligned = PointeeType.getQualifiers().hasUnaligned();
3787 }
3788
3789 // Member pointer types like "const int A::*" are represented by having RTTI
3790 // for "int A::*" and separately storing the const qualifier.
3791 if (const auto *MPTy = T->getAs<MemberPointerType>())
3792 T = Context.getMemberPointerType(PointeeType.getUnqualifiedType(),
3793 MPTy->getClass());
3794
3795 // Pointer types like "const int * const *" are represented by having RTTI
3796 // for "const int **" and separately storing the const qualifier.
3797 if (T->isPointerType())
3798 T = Context.getPointerType(PointeeType.getUnqualifiedType());
3799
3800 return T;
3801 }
3802
3803 CatchTypeInfo
getAddrOfCXXCatchHandlerType(QualType Type,QualType CatchHandlerType)3804 MicrosoftCXXABI::getAddrOfCXXCatchHandlerType(QualType Type,
3805 QualType CatchHandlerType) {
3806 // TypeDescriptors for exceptions never have qualified pointer types,
3807 // qualifiers are stored separately in order to support qualification
3808 // conversions.
3809 bool IsConst, IsVolatile, IsUnaligned;
3810 Type =
3811 decomposeTypeForEH(getContext(), Type, IsConst, IsVolatile, IsUnaligned);
3812
3813 bool IsReference = CatchHandlerType->isReferenceType();
3814
3815 uint32_t Flags = 0;
3816 if (IsConst)
3817 Flags |= 1;
3818 if (IsVolatile)
3819 Flags |= 2;
3820 if (IsUnaligned)
3821 Flags |= 4;
3822 if (IsReference)
3823 Flags |= 8;
3824
3825 return CatchTypeInfo{getAddrOfRTTIDescriptor(Type)->stripPointerCasts(),
3826 Flags};
3827 }
3828
3829 /// Gets a TypeDescriptor. Returns a llvm::Constant * rather than a
3830 /// llvm::GlobalVariable * because different type descriptors have different
3831 /// types, and need to be abstracted. They are abstracting by casting the
3832 /// address to an Int8PtrTy.
getAddrOfRTTIDescriptor(QualType Type)3833 llvm::Constant *MicrosoftCXXABI::getAddrOfRTTIDescriptor(QualType Type) {
3834 SmallString<256> MangledName;
3835 {
3836 llvm::raw_svector_ostream Out(MangledName);
3837 getMangleContext().mangleCXXRTTI(Type, Out);
3838 }
3839
3840 // Check to see if we've already declared this TypeDescriptor.
3841 if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName))
3842 return llvm::ConstantExpr::getBitCast(GV, CGM.Int8PtrTy);
3843
3844 // Note for the future: If we would ever like to do deferred emission of
3845 // RTTI, check if emitting vtables opportunistically need any adjustment.
3846
3847 // Compute the fields for the TypeDescriptor.
3848 SmallString<256> TypeInfoString;
3849 {
3850 llvm::raw_svector_ostream Out(TypeInfoString);
3851 getMangleContext().mangleCXXRTTIName(Type, Out);
3852 }
3853
3854 // Declare and initialize the TypeDescriptor.
3855 llvm::Constant *Fields[] = {
3856 getTypeInfoVTable(CGM), // VFPtr
3857 llvm::ConstantPointerNull::get(CGM.Int8PtrTy), // Runtime data
3858 llvm::ConstantDataArray::getString(CGM.getLLVMContext(), TypeInfoString)};
3859 llvm::StructType *TypeDescriptorType =
3860 getTypeDescriptorType(TypeInfoString);
3861 auto *Var = new llvm::GlobalVariable(
3862 CGM.getModule(), TypeDescriptorType, /*isConstant=*/false,
3863 getLinkageForRTTI(Type),
3864 llvm::ConstantStruct::get(TypeDescriptorType, Fields),
3865 MangledName);
3866 if (Var->isWeakForLinker())
3867 Var->setComdat(CGM.getModule().getOrInsertComdat(Var->getName()));
3868 return llvm::ConstantExpr::getBitCast(Var, CGM.Int8PtrTy);
3869 }
3870
3871 /// Gets or a creates a Microsoft CompleteObjectLocator.
3872 llvm::GlobalVariable *
getMSCompleteObjectLocator(const CXXRecordDecl * RD,const VPtrInfo & Info)3873 MicrosoftCXXABI::getMSCompleteObjectLocator(const CXXRecordDecl *RD,
3874 const VPtrInfo &Info) {
3875 return MSRTTIBuilder(*this, RD).getCompleteObjectLocator(Info);
3876 }
3877
emitCXXStructor(GlobalDecl GD)3878 void MicrosoftCXXABI::emitCXXStructor(GlobalDecl GD) {
3879 if (auto *ctor = dyn_cast<CXXConstructorDecl>(GD.getDecl())) {
3880 // There are no constructor variants, always emit the complete destructor.
3881 llvm::Function *Fn =
3882 CGM.codegenCXXStructor(GD.getWithCtorType(Ctor_Complete));
3883 CGM.maybeSetTrivialComdat(*ctor, *Fn);
3884 return;
3885 }
3886
3887 auto *dtor = cast<CXXDestructorDecl>(GD.getDecl());
3888
3889 // Emit the base destructor if the base and complete (vbase) destructors are
3890 // equivalent. This effectively implements -mconstructor-aliases as part of
3891 // the ABI.
3892 if (GD.getDtorType() == Dtor_Complete &&
3893 dtor->getParent()->getNumVBases() == 0)
3894 GD = GD.getWithDtorType(Dtor_Base);
3895
3896 // The base destructor is equivalent to the base destructor of its
3897 // base class if there is exactly one non-virtual base class with a
3898 // non-trivial destructor, there are no fields with a non-trivial
3899 // destructor, and the body of the destructor is trivial.
3900 if (GD.getDtorType() == Dtor_Base && !CGM.TryEmitBaseDestructorAsAlias(dtor))
3901 return;
3902
3903 llvm::Function *Fn = CGM.codegenCXXStructor(GD);
3904 if (Fn->isWeakForLinker())
3905 Fn->setComdat(CGM.getModule().getOrInsertComdat(Fn->getName()));
3906 }
3907
3908 llvm::Function *
getAddrOfCXXCtorClosure(const CXXConstructorDecl * CD,CXXCtorType CT)3909 MicrosoftCXXABI::getAddrOfCXXCtorClosure(const CXXConstructorDecl *CD,
3910 CXXCtorType CT) {
3911 assert(CT == Ctor_CopyingClosure || CT == Ctor_DefaultClosure);
3912
3913 // Calculate the mangled name.
3914 SmallString<256> ThunkName;
3915 llvm::raw_svector_ostream Out(ThunkName);
3916 getMangleContext().mangleCXXCtor(CD, CT, Out);
3917
3918 // If the thunk has been generated previously, just return it.
3919 if (llvm::GlobalValue *GV = CGM.getModule().getNamedValue(ThunkName))
3920 return cast<llvm::Function>(GV);
3921
3922 // Create the llvm::Function.
3923 const CGFunctionInfo &FnInfo = CGM.getTypes().arrangeMSCtorClosure(CD, CT);
3924 llvm::FunctionType *ThunkTy = CGM.getTypes().GetFunctionType(FnInfo);
3925 const CXXRecordDecl *RD = CD->getParent();
3926 QualType RecordTy = getContext().getRecordType(RD);
3927 llvm::Function *ThunkFn = llvm::Function::Create(
3928 ThunkTy, getLinkageForRTTI(RecordTy), ThunkName.str(), &CGM.getModule());
3929 ThunkFn->setCallingConv(static_cast<llvm::CallingConv::ID>(
3930 FnInfo.getEffectiveCallingConvention()));
3931 if (ThunkFn->isWeakForLinker())
3932 ThunkFn->setComdat(CGM.getModule().getOrInsertComdat(ThunkFn->getName()));
3933 bool IsCopy = CT == Ctor_CopyingClosure;
3934
3935 // Start codegen.
3936 CodeGenFunction CGF(CGM);
3937 CGF.CurGD = GlobalDecl(CD, Ctor_Complete);
3938
3939 // Build FunctionArgs.
3940 FunctionArgList FunctionArgs;
3941
3942 // A constructor always starts with a 'this' pointer as its first argument.
3943 buildThisParam(CGF, FunctionArgs);
3944
3945 // Following the 'this' pointer is a reference to the source object that we
3946 // are copying from.
3947 ImplicitParamDecl SrcParam(
3948 getContext(), /*DC=*/nullptr, SourceLocation(),
3949 &getContext().Idents.get("src"),
3950 getContext().getLValueReferenceType(RecordTy,
3951 /*SpelledAsLValue=*/true),
3952 ImplicitParamDecl::Other);
3953 if (IsCopy)
3954 FunctionArgs.push_back(&SrcParam);
3955
3956 // Constructors for classes which utilize virtual bases have an additional
3957 // parameter which indicates whether or not it is being delegated to by a more
3958 // derived constructor.
3959 ImplicitParamDecl IsMostDerived(getContext(), /*DC=*/nullptr,
3960 SourceLocation(),
3961 &getContext().Idents.get("is_most_derived"),
3962 getContext().IntTy, ImplicitParamDecl::Other);
3963 // Only add the parameter to the list if the class has virtual bases.
3964 if (RD->getNumVBases() > 0)
3965 FunctionArgs.push_back(&IsMostDerived);
3966
3967 // Start defining the function.
3968 auto NL = ApplyDebugLocation::CreateEmpty(CGF);
3969 CGF.StartFunction(GlobalDecl(), FnInfo.getReturnType(), ThunkFn, FnInfo,
3970 FunctionArgs, CD->getLocation(), SourceLocation());
3971 // Create a scope with an artificial location for the body of this function.
3972 auto AL = ApplyDebugLocation::CreateArtificial(CGF);
3973 setCXXABIThisValue(CGF, loadIncomingCXXThis(CGF));
3974 llvm::Value *This = getThisValue(CGF);
3975
3976 llvm::Value *SrcVal =
3977 IsCopy ? CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(&SrcParam), "src")
3978 : nullptr;
3979
3980 CallArgList Args;
3981
3982 // Push the this ptr.
3983 Args.add(RValue::get(This), CD->getThisType());
3984
3985 // Push the src ptr.
3986 if (SrcVal)
3987 Args.add(RValue::get(SrcVal), SrcParam.getType());
3988
3989 // Add the rest of the default arguments.
3990 SmallVector<const Stmt *, 4> ArgVec;
3991 ArrayRef<ParmVarDecl *> params = CD->parameters().drop_front(IsCopy ? 1 : 0);
3992 for (const ParmVarDecl *PD : params) {
3993 assert(PD->hasDefaultArg() && "ctor closure lacks default args");
3994 ArgVec.push_back(PD->getDefaultArg());
3995 }
3996
3997 CodeGenFunction::RunCleanupsScope Cleanups(CGF);
3998
3999 const auto *FPT = CD->getType()->castAs<FunctionProtoType>();
4000 CGF.EmitCallArgs(Args, FPT, llvm::makeArrayRef(ArgVec), CD, IsCopy ? 1 : 0);
4001
4002 // Insert any ABI-specific implicit constructor arguments.
4003 AddedStructorArgs ExtraArgs =
4004 addImplicitConstructorArgs(CGF, CD, Ctor_Complete,
4005 /*ForVirtualBase=*/false,
4006 /*Delegating=*/false, Args);
4007 // Call the destructor with our arguments.
4008 llvm::Constant *CalleePtr =
4009 CGM.getAddrOfCXXStructor(GlobalDecl(CD, Ctor_Complete));
4010 CGCallee Callee =
4011 CGCallee::forDirect(CalleePtr, GlobalDecl(CD, Ctor_Complete));
4012 const CGFunctionInfo &CalleeInfo = CGM.getTypes().arrangeCXXConstructorCall(
4013 Args, CD, Ctor_Complete, ExtraArgs.Prefix, ExtraArgs.Suffix);
4014 CGF.EmitCall(CalleeInfo, Callee, ReturnValueSlot(), Args);
4015
4016 Cleanups.ForceCleanup();
4017
4018 // Emit the ret instruction, remove any temporary instructions created for the
4019 // aid of CodeGen.
4020 CGF.FinishFunction(SourceLocation());
4021
4022 return ThunkFn;
4023 }
4024
getCatchableType(QualType T,uint32_t NVOffset,int32_t VBPtrOffset,uint32_t VBIndex)4025 llvm::Constant *MicrosoftCXXABI::getCatchableType(QualType T,
4026 uint32_t NVOffset,
4027 int32_t VBPtrOffset,
4028 uint32_t VBIndex) {
4029 assert(!T->isReferenceType());
4030
4031 CXXRecordDecl *RD = T->getAsCXXRecordDecl();
4032 const CXXConstructorDecl *CD =
4033 RD ? CGM.getContext().getCopyConstructorForExceptionObject(RD) : nullptr;
4034 CXXCtorType CT = Ctor_Complete;
4035 if (CD)
4036 if (!hasDefaultCXXMethodCC(getContext(), CD) || CD->getNumParams() != 1)
4037 CT = Ctor_CopyingClosure;
4038
4039 uint32_t Size = getContext().getTypeSizeInChars(T).getQuantity();
4040 SmallString<256> MangledName;
4041 {
4042 llvm::raw_svector_ostream Out(MangledName);
4043 getMangleContext().mangleCXXCatchableType(T, CD, CT, Size, NVOffset,
4044 VBPtrOffset, VBIndex, Out);
4045 }
4046 if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName))
4047 return getImageRelativeConstant(GV);
4048
4049 // The TypeDescriptor is used by the runtime to determine if a catch handler
4050 // is appropriate for the exception object.
4051 llvm::Constant *TD = getImageRelativeConstant(getAddrOfRTTIDescriptor(T));
4052
4053 // The runtime is responsible for calling the copy constructor if the
4054 // exception is caught by value.
4055 llvm::Constant *CopyCtor;
4056 if (CD) {
4057 if (CT == Ctor_CopyingClosure)
4058 CopyCtor = getAddrOfCXXCtorClosure(CD, Ctor_CopyingClosure);
4059 else
4060 CopyCtor = CGM.getAddrOfCXXStructor(GlobalDecl(CD, Ctor_Complete));
4061
4062 CopyCtor = llvm::ConstantExpr::getBitCast(CopyCtor, CGM.Int8PtrTy);
4063 } else {
4064 CopyCtor = llvm::Constant::getNullValue(CGM.Int8PtrTy);
4065 }
4066 CopyCtor = getImageRelativeConstant(CopyCtor);
4067
4068 bool IsScalar = !RD;
4069 bool HasVirtualBases = false;
4070 bool IsStdBadAlloc = false; // std::bad_alloc is special for some reason.
4071 QualType PointeeType = T;
4072 if (T->isPointerType())
4073 PointeeType = T->getPointeeType();
4074 if (const CXXRecordDecl *RD = PointeeType->getAsCXXRecordDecl()) {
4075 HasVirtualBases = RD->getNumVBases() > 0;
4076 if (IdentifierInfo *II = RD->getIdentifier())
4077 IsStdBadAlloc = II->isStr("bad_alloc") && RD->isInStdNamespace();
4078 }
4079
4080 // Encode the relevant CatchableType properties into the Flags bitfield.
4081 // FIXME: Figure out how bits 2 or 8 can get set.
4082 uint32_t Flags = 0;
4083 if (IsScalar)
4084 Flags |= 1;
4085 if (HasVirtualBases)
4086 Flags |= 4;
4087 if (IsStdBadAlloc)
4088 Flags |= 16;
4089
4090 llvm::Constant *Fields[] = {
4091 llvm::ConstantInt::get(CGM.IntTy, Flags), // Flags
4092 TD, // TypeDescriptor
4093 llvm::ConstantInt::get(CGM.IntTy, NVOffset), // NonVirtualAdjustment
4094 llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset), // OffsetToVBPtr
4095 llvm::ConstantInt::get(CGM.IntTy, VBIndex), // VBTableIndex
4096 llvm::ConstantInt::get(CGM.IntTy, Size), // Size
4097 CopyCtor // CopyCtor
4098 };
4099 llvm::StructType *CTType = getCatchableTypeType();
4100 auto *GV = new llvm::GlobalVariable(
4101 CGM.getModule(), CTType, /*isConstant=*/true, getLinkageForRTTI(T),
4102 llvm::ConstantStruct::get(CTType, Fields), MangledName);
4103 GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
4104 GV->setSection(".xdata");
4105 if (GV->isWeakForLinker())
4106 GV->setComdat(CGM.getModule().getOrInsertComdat(GV->getName()));
4107 return getImageRelativeConstant(GV);
4108 }
4109
getCatchableTypeArray(QualType T)4110 llvm::GlobalVariable *MicrosoftCXXABI::getCatchableTypeArray(QualType T) {
4111 assert(!T->isReferenceType());
4112
4113 // See if we've already generated a CatchableTypeArray for this type before.
4114 llvm::GlobalVariable *&CTA = CatchableTypeArrays[T];
4115 if (CTA)
4116 return CTA;
4117
4118 // Ensure that we don't have duplicate entries in our CatchableTypeArray by
4119 // using a SmallSetVector. Duplicates may arise due to virtual bases
4120 // occurring more than once in the hierarchy.
4121 llvm::SmallSetVector<llvm::Constant *, 2> CatchableTypes;
4122
4123 // C++14 [except.handle]p3:
4124 // A handler is a match for an exception object of type E if [...]
4125 // - the handler is of type cv T or cv T& and T is an unambiguous public
4126 // base class of E, or
4127 // - the handler is of type cv T or const T& where T is a pointer type and
4128 // E is a pointer type that can be converted to T by [...]
4129 // - a standard pointer conversion (4.10) not involving conversions to
4130 // pointers to private or protected or ambiguous classes
4131 const CXXRecordDecl *MostDerivedClass = nullptr;
4132 bool IsPointer = T->isPointerType();
4133 if (IsPointer)
4134 MostDerivedClass = T->getPointeeType()->getAsCXXRecordDecl();
4135 else
4136 MostDerivedClass = T->getAsCXXRecordDecl();
4137
4138 // Collect all the unambiguous public bases of the MostDerivedClass.
4139 if (MostDerivedClass) {
4140 const ASTContext &Context = getContext();
4141 const ASTRecordLayout &MostDerivedLayout =
4142 Context.getASTRecordLayout(MostDerivedClass);
4143 MicrosoftVTableContext &VTableContext = CGM.getMicrosoftVTableContext();
4144 SmallVector<MSRTTIClass, 8> Classes;
4145 serializeClassHierarchy(Classes, MostDerivedClass);
4146 Classes.front().initialize(/*Parent=*/nullptr, /*Specifier=*/nullptr);
4147 detectAmbiguousBases(Classes);
4148 for (const MSRTTIClass &Class : Classes) {
4149 // Skip any ambiguous or private bases.
4150 if (Class.Flags &
4151 (MSRTTIClass::IsPrivateOnPath | MSRTTIClass::IsAmbiguous))
4152 continue;
4153 // Write down how to convert from a derived pointer to a base pointer.
4154 uint32_t OffsetInVBTable = 0;
4155 int32_t VBPtrOffset = -1;
4156 if (Class.VirtualRoot) {
4157 OffsetInVBTable =
4158 VTableContext.getVBTableIndex(MostDerivedClass, Class.VirtualRoot)*4;
4159 VBPtrOffset = MostDerivedLayout.getVBPtrOffset().getQuantity();
4160 }
4161
4162 // Turn our record back into a pointer if the exception object is a
4163 // pointer.
4164 QualType RTTITy = QualType(Class.RD->getTypeForDecl(), 0);
4165 if (IsPointer)
4166 RTTITy = Context.getPointerType(RTTITy);
4167 CatchableTypes.insert(getCatchableType(RTTITy, Class.OffsetInVBase,
4168 VBPtrOffset, OffsetInVBTable));
4169 }
4170 }
4171
4172 // C++14 [except.handle]p3:
4173 // A handler is a match for an exception object of type E if
4174 // - The handler is of type cv T or cv T& and E and T are the same type
4175 // (ignoring the top-level cv-qualifiers)
4176 CatchableTypes.insert(getCatchableType(T));
4177
4178 // C++14 [except.handle]p3:
4179 // A handler is a match for an exception object of type E if
4180 // - the handler is of type cv T or const T& where T is a pointer type and
4181 // E is a pointer type that can be converted to T by [...]
4182 // - a standard pointer conversion (4.10) not involving conversions to
4183 // pointers to private or protected or ambiguous classes
4184 //
4185 // C++14 [conv.ptr]p2:
4186 // A prvalue of type "pointer to cv T," where T is an object type, can be
4187 // converted to a prvalue of type "pointer to cv void".
4188 if (IsPointer && T->getPointeeType()->isObjectType())
4189 CatchableTypes.insert(getCatchableType(getContext().VoidPtrTy));
4190
4191 // C++14 [except.handle]p3:
4192 // A handler is a match for an exception object of type E if [...]
4193 // - the handler is of type cv T or const T& where T is a pointer or
4194 // pointer to member type and E is std::nullptr_t.
4195 //
4196 // We cannot possibly list all possible pointer types here, making this
4197 // implementation incompatible with the standard. However, MSVC includes an
4198 // entry for pointer-to-void in this case. Let's do the same.
4199 if (T->isNullPtrType())
4200 CatchableTypes.insert(getCatchableType(getContext().VoidPtrTy));
4201
4202 uint32_t NumEntries = CatchableTypes.size();
4203 llvm::Type *CTType =
4204 getImageRelativeType(getCatchableTypeType()->getPointerTo());
4205 llvm::ArrayType *AT = llvm::ArrayType::get(CTType, NumEntries);
4206 llvm::StructType *CTAType = getCatchableTypeArrayType(NumEntries);
4207 llvm::Constant *Fields[] = {
4208 llvm::ConstantInt::get(CGM.IntTy, NumEntries), // NumEntries
4209 llvm::ConstantArray::get(
4210 AT, llvm::makeArrayRef(CatchableTypes.begin(),
4211 CatchableTypes.end())) // CatchableTypes
4212 };
4213 SmallString<256> MangledName;
4214 {
4215 llvm::raw_svector_ostream Out(MangledName);
4216 getMangleContext().mangleCXXCatchableTypeArray(T, NumEntries, Out);
4217 }
4218 CTA = new llvm::GlobalVariable(
4219 CGM.getModule(), CTAType, /*isConstant=*/true, getLinkageForRTTI(T),
4220 llvm::ConstantStruct::get(CTAType, Fields), MangledName);
4221 CTA->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
4222 CTA->setSection(".xdata");
4223 if (CTA->isWeakForLinker())
4224 CTA->setComdat(CGM.getModule().getOrInsertComdat(CTA->getName()));
4225 return CTA;
4226 }
4227
getThrowInfo(QualType T)4228 llvm::GlobalVariable *MicrosoftCXXABI::getThrowInfo(QualType T) {
4229 bool IsConst, IsVolatile, IsUnaligned;
4230 T = decomposeTypeForEH(getContext(), T, IsConst, IsVolatile, IsUnaligned);
4231
4232 // The CatchableTypeArray enumerates the various (CV-unqualified) types that
4233 // the exception object may be caught as.
4234 llvm::GlobalVariable *CTA = getCatchableTypeArray(T);
4235 // The first field in a CatchableTypeArray is the number of CatchableTypes.
4236 // This is used as a component of the mangled name which means that we need to
4237 // know what it is in order to see if we have previously generated the
4238 // ThrowInfo.
4239 uint32_t NumEntries =
4240 cast<llvm::ConstantInt>(CTA->getInitializer()->getAggregateElement(0U))
4241 ->getLimitedValue();
4242
4243 SmallString<256> MangledName;
4244 {
4245 llvm::raw_svector_ostream Out(MangledName);
4246 getMangleContext().mangleCXXThrowInfo(T, IsConst, IsVolatile, IsUnaligned,
4247 NumEntries, Out);
4248 }
4249
4250 // Reuse a previously generated ThrowInfo if we have generated an appropriate
4251 // one before.
4252 if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName))
4253 return GV;
4254
4255 // The RTTI TypeDescriptor uses an unqualified type but catch clauses must
4256 // be at least as CV qualified. Encode this requirement into the Flags
4257 // bitfield.
4258 uint32_t Flags = 0;
4259 if (IsConst)
4260 Flags |= 1;
4261 if (IsVolatile)
4262 Flags |= 2;
4263 if (IsUnaligned)
4264 Flags |= 4;
4265
4266 // The cleanup-function (a destructor) must be called when the exception
4267 // object's lifetime ends.
4268 llvm::Constant *CleanupFn = llvm::Constant::getNullValue(CGM.Int8PtrTy);
4269 if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
4270 if (CXXDestructorDecl *DtorD = RD->getDestructor())
4271 if (!DtorD->isTrivial())
4272 CleanupFn = llvm::ConstantExpr::getBitCast(
4273 CGM.getAddrOfCXXStructor(GlobalDecl(DtorD, Dtor_Complete)),
4274 CGM.Int8PtrTy);
4275 // This is unused as far as we can tell, initialize it to null.
4276 llvm::Constant *ForwardCompat =
4277 getImageRelativeConstant(llvm::Constant::getNullValue(CGM.Int8PtrTy));
4278 llvm::Constant *PointerToCatchableTypes = getImageRelativeConstant(
4279 llvm::ConstantExpr::getBitCast(CTA, CGM.Int8PtrTy));
4280 llvm::StructType *TIType = getThrowInfoType();
4281 llvm::Constant *Fields[] = {
4282 llvm::ConstantInt::get(CGM.IntTy, Flags), // Flags
4283 getImageRelativeConstant(CleanupFn), // CleanupFn
4284 ForwardCompat, // ForwardCompat
4285 PointerToCatchableTypes // CatchableTypeArray
4286 };
4287 auto *GV = new llvm::GlobalVariable(
4288 CGM.getModule(), TIType, /*isConstant=*/true, getLinkageForRTTI(T),
4289 llvm::ConstantStruct::get(TIType, Fields), StringRef(MangledName));
4290 GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
4291 GV->setSection(".xdata");
4292 if (GV->isWeakForLinker())
4293 GV->setComdat(CGM.getModule().getOrInsertComdat(GV->getName()));
4294 return GV;
4295 }
4296
emitThrow(CodeGenFunction & CGF,const CXXThrowExpr * E)4297 void MicrosoftCXXABI::emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) {
4298 const Expr *SubExpr = E->getSubExpr();
4299 QualType ThrowType = SubExpr->getType();
4300 // The exception object lives on the stack and it's address is passed to the
4301 // runtime function.
4302 Address AI = CGF.CreateMemTemp(ThrowType);
4303 CGF.EmitAnyExprToMem(SubExpr, AI, ThrowType.getQualifiers(),
4304 /*IsInit=*/true);
4305
4306 // The so-called ThrowInfo is used to describe how the exception object may be
4307 // caught.
4308 llvm::GlobalVariable *TI = getThrowInfo(ThrowType);
4309
4310 // Call into the runtime to throw the exception.
4311 llvm::Value *Args[] = {
4312 CGF.Builder.CreateBitCast(AI.getPointer(), CGM.Int8PtrTy),
4313 TI
4314 };
4315 CGF.EmitNoreturnRuntimeCallOrInvoke(getThrowFn(), Args);
4316 }
4317
4318 std::pair<llvm::Value *, const CXXRecordDecl *>
LoadVTablePtr(CodeGenFunction & CGF,Address This,const CXXRecordDecl * RD)4319 MicrosoftCXXABI::LoadVTablePtr(CodeGenFunction &CGF, Address This,
4320 const CXXRecordDecl *RD) {
4321 std::tie(This, std::ignore, RD) =
4322 performBaseAdjustment(CGF, This, QualType(RD->getTypeForDecl(), 0));
4323 return {CGF.GetVTablePtr(This, CGM.Int8PtrTy, RD), RD};
4324 }
4325