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MicrosoftCXXABI.cpp
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//===--- MicrosoftCXXABI.cpp - Emit LLVM Code from ASTs for a Module ------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This provides C++ code generation targeting the Microsoft Visual C++ ABI.
// The class in this file generates structures that follow the Microsoft
// Visual C++ ABI, which is actually not very well documented at all outside
// of Microsoft.
//
//===----------------------------------------------------------------------===//
#include "CGCXXABI.h"
#include "CGCleanup.h"
#include "CGVTables.h"
#include "CodeGenModule.h"
#include "CodeGenTypes.h"
#include "TargetInfo.h"
#include "clang/CodeGen/ConstantInitBuilder.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/StmtCXX.h"
#include "clang/AST/VTableBuilder.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringSet.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/Intrinsics.h"
using namespace clang;
using namespace CodeGen;
namespace {
/// Holds all the vbtable globals for a given class.
struct VBTableGlobals {
const VPtrInfoVector *VBTables;
SmallVector<llvm::GlobalVariable *, 2> Globals;
};
class MicrosoftCXXABI : public CGCXXABI {
public:
MicrosoftCXXABI(CodeGenModule &CGM)
: CGCXXABI(CGM), BaseClassDescriptorType(nullptr),
ClassHierarchyDescriptorType(nullptr),
CompleteObjectLocatorType(nullptr), CatchableTypeType(nullptr),
ThrowInfoType(nullptr) {}
bool HasThisReturn(GlobalDecl GD) const override;
bool hasMostDerivedReturn(GlobalDecl GD) const override;
bool classifyReturnType(CGFunctionInfo &FI) const override;
RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const override;
bool isSRetParameterAfterThis() const override { return true; }
bool isThisCompleteObject(GlobalDecl GD) const override {
// The Microsoft ABI doesn't use separate complete-object vs.
// base-object variants of constructors, but it does of destructors.
if (isa<CXXDestructorDecl>(GD.getDecl())) {
switch (GD.getDtorType()) {
case Dtor_Complete:
case Dtor_Deleting:
return true;
case Dtor_Base:
return false;
case Dtor_Comdat: llvm_unreachable("emitting dtor comdat as function?");
}
llvm_unreachable("bad dtor kind");
}
// No other kinds.
return false;
}
size_t getSrcArgforCopyCtor(const CXXConstructorDecl *CD,
FunctionArgList &Args) const override {
assert(Args.size() >= 2 &&
"expected the arglist to have at least two args!");
// The 'most_derived' parameter goes second if the ctor is variadic and
// has v-bases.
if (CD->getParent()->getNumVBases() > 0 &&
CD->getType()->castAs<FunctionProtoType>()->isVariadic())
return 2;
return 1;
}
std::vector<CharUnits> getVBPtrOffsets(const CXXRecordDecl *RD) override {
std::vector<CharUnits> VBPtrOffsets;
const ASTContext &Context = getContext();
const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
const VBTableGlobals &VBGlobals = enumerateVBTables(RD);
for (const std::unique_ptr<VPtrInfo> &VBT : *VBGlobals.VBTables) {
const ASTRecordLayout &SubobjectLayout =
Context.getASTRecordLayout(VBT->IntroducingObject);
CharUnits Offs = VBT->NonVirtualOffset;
Offs += SubobjectLayout.getVBPtrOffset();
if (VBT->getVBaseWithVPtr())
Offs += Layout.getVBaseClassOffset(VBT->getVBaseWithVPtr());
VBPtrOffsets.push_back(Offs);
}
llvm::array_pod_sort(VBPtrOffsets.begin(), VBPtrOffsets.end());
return VBPtrOffsets;
}
StringRef GetPureVirtualCallName() override { return "_purecall"; }
StringRef GetDeletedVirtualCallName() override { return "_purecall"; }
void emitVirtualObjectDelete(CodeGenFunction &CGF, const CXXDeleteExpr *DE,
Address Ptr, QualType ElementType,
const CXXDestructorDecl *Dtor) override;
void emitRethrow(CodeGenFunction &CGF, bool isNoReturn) override;
void emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) override;
void emitBeginCatch(CodeGenFunction &CGF, const CXXCatchStmt *C) override;
llvm::GlobalVariable *getMSCompleteObjectLocator(const CXXRecordDecl *RD,
const VPtrInfo &Info);
llvm::Constant *getAddrOfRTTIDescriptor(QualType Ty) override;
CatchTypeInfo
getAddrOfCXXCatchHandlerType(QualType Ty, QualType CatchHandlerType) override;
/// MSVC needs an extra flag to indicate a catchall.
CatchTypeInfo getCatchAllTypeInfo() override {
return CatchTypeInfo{nullptr, 0x40};
}
bool shouldTypeidBeNullChecked(bool IsDeref, QualType SrcRecordTy) override;
void EmitBadTypeidCall(CodeGenFunction &CGF) override;
llvm::Value *EmitTypeid(CodeGenFunction &CGF, QualType SrcRecordTy,
Address ThisPtr,
llvm::Type *StdTypeInfoPtrTy) override;
bool shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,
QualType SrcRecordTy) override;
llvm::Value *EmitDynamicCastCall(CodeGenFunction &CGF, Address Value,
QualType SrcRecordTy, QualType DestTy,
QualType DestRecordTy,
llvm::BasicBlock *CastEnd) override;
llvm::Value *EmitDynamicCastToVoid(CodeGenFunction &CGF, Address Value,
QualType SrcRecordTy,
QualType DestTy) override;
bool EmitBadCastCall(CodeGenFunction &CGF) override;
bool canSpeculativelyEmitVTable(const CXXRecordDecl *RD) const override {
return false;
}
llvm::Value *
GetVirtualBaseClassOffset(CodeGenFunction &CGF, Address This,
const CXXRecordDecl *ClassDecl,
const CXXRecordDecl *BaseClassDecl) override;
llvm::BasicBlock *
EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
const CXXRecordDecl *RD) override;
llvm::BasicBlock *
EmitDtorCompleteObjectHandler(CodeGenFunction &CGF);
void initializeHiddenVirtualInheritanceMembers(CodeGenFunction &CGF,
const CXXRecordDecl *RD) override;
void EmitCXXConstructors(const CXXConstructorDecl *D) override;
// Background on MSVC destructors
// ==============================
//
// Both Itanium and MSVC ABIs have destructor variants. The variant names
// roughly correspond in the following way:
// Itanium Microsoft
// Base -> no name, just ~Class
// Complete -> vbase destructor
// Deleting -> scalar deleting destructor
// vector deleting destructor
//
// The base and complete destructors are the same as in Itanium, although the
// complete destructor does not accept a VTT parameter when there are virtual
// bases. A separate mechanism involving vtordisps is used to ensure that
// virtual methods of destroyed subobjects are not called.
//
// The deleting destructors accept an i32 bitfield as a second parameter. Bit
// 1 indicates if the memory should be deleted. Bit 2 indicates if the this
// pointer points to an array. The scalar deleting destructor assumes that
// bit 2 is zero, and therefore does not contain a loop.
//
// For virtual destructors, only one entry is reserved in the vftable, and it
// always points to the vector deleting destructor. The vector deleting
// destructor is the most general, so it can be used to destroy objects in
// place, delete single heap objects, or delete arrays.
//
// A TU defining a non-inline destructor is only guaranteed to emit a base
// destructor, and all of the other variants are emitted on an as-needed basis
// in COMDATs. Because a non-base destructor can be emitted in a TU that
// lacks a definition for the destructor, non-base destructors must always
// delegate to or alias the base destructor.
AddedStructorArgs
buildStructorSignature(const CXXMethodDecl *MD, StructorType T,
SmallVectorImpl<CanQualType> &ArgTys) override;
/// Non-base dtors should be emitted as delegating thunks in this ABI.
bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor,
CXXDtorType DT) const override {
return DT != Dtor_Base;
}
void EmitCXXDestructors(const CXXDestructorDecl *D) override;
const CXXRecordDecl *
getThisArgumentTypeForMethod(const CXXMethodDecl *MD) override {
MD = MD->getCanonicalDecl();
if (MD->isVirtual() && !isa<CXXDestructorDecl>(MD)) {
MicrosoftVTableContext::MethodVFTableLocation ML =
CGM.getMicrosoftVTableContext().getMethodVFTableLocation(MD);
// The vbases might be ordered differently in the final overrider object
// and the complete object, so the "this" argument may sometimes point to
// memory that has no particular type (e.g. past the complete object).
// In this case, we just use a generic pointer type.
// FIXME: might want to have a more precise type in the non-virtual
// multiple inheritance case.
if (ML.VBase || !ML.VFPtrOffset.isZero())
return nullptr;
}
return MD->getParent();
}
Address
adjustThisArgumentForVirtualFunctionCall(CodeGenFunction &CGF, GlobalDecl GD,
Address This,
bool VirtualCall) override;
void addImplicitStructorParams(CodeGenFunction &CGF, QualType &ResTy,
FunctionArgList &Params) override;
llvm::Value *adjustThisParameterInVirtualFunctionPrologue(
CodeGenFunction &CGF, GlobalDecl GD, llvm::Value *This) override;
void EmitInstanceFunctionProlog(CodeGenFunction &CGF) override;
AddedStructorArgs
addImplicitConstructorArgs(CodeGenFunction &CGF, const CXXConstructorDecl *D,
CXXCtorType Type, bool ForVirtualBase,
bool Delegating, CallArgList &Args) override;
void EmitDestructorCall(CodeGenFunction &CGF, const CXXDestructorDecl *DD,
CXXDtorType Type, bool ForVirtualBase,
bool Delegating, Address This) override;
void emitVTableTypeMetadata(const VPtrInfo &Info, const CXXRecordDecl *RD,
llvm::GlobalVariable *VTable);
void emitVTableDefinitions(CodeGenVTables &CGVT,
const CXXRecordDecl *RD) override;
bool isVirtualOffsetNeededForVTableField(CodeGenFunction &CGF,
CodeGenFunction::VPtr Vptr) override;
/// Don't initialize vptrs if dynamic class
/// is marked with with the 'novtable' attribute.
bool doStructorsInitializeVPtrs(const CXXRecordDecl *VTableClass) override {
return !VTableClass->hasAttr<MSNoVTableAttr>();
}
llvm::Constant *
getVTableAddressPoint(BaseSubobject Base,
const CXXRecordDecl *VTableClass) override;
llvm::Value *getVTableAddressPointInStructor(
CodeGenFunction &CGF, const CXXRecordDecl *VTableClass,
BaseSubobject Base, const CXXRecordDecl *NearestVBase) override;
llvm::Constant *
getVTableAddressPointForConstExpr(BaseSubobject Base,
const CXXRecordDecl *VTableClass) override;
llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD,
CharUnits VPtrOffset) override;
CGCallee getVirtualFunctionPointer(CodeGenFunction &CGF, GlobalDecl GD,
Address This, llvm::Type *Ty,
SourceLocation Loc) override;
llvm::Value *EmitVirtualDestructorCall(CodeGenFunction &CGF,
const CXXDestructorDecl *Dtor,
CXXDtorType DtorType,
Address This,
const CXXMemberCallExpr *CE) override;
void adjustCallArgsForDestructorThunk(CodeGenFunction &CGF, GlobalDecl GD,
CallArgList &CallArgs) override {
assert(GD.getDtorType() == Dtor_Deleting &&
"Only deleting destructor thunks are available in this ABI");
CallArgs.add(RValue::get(getStructorImplicitParamValue(CGF)),
getContext().IntTy);
}
void emitVirtualInheritanceTables(const CXXRecordDecl *RD) override;
llvm::GlobalVariable *
getAddrOfVBTable(const VPtrInfo &VBT, const CXXRecordDecl *RD,
llvm::GlobalVariable::LinkageTypes Linkage);
llvm::GlobalVariable *
getAddrOfVirtualDisplacementMap(const CXXRecordDecl *SrcRD,
const CXXRecordDecl *DstRD) {
SmallString<256> OutName;
llvm::raw_svector_ostream Out(OutName);
getMangleContext().mangleCXXVirtualDisplacementMap(SrcRD, DstRD, Out);
StringRef MangledName = OutName.str();
if (auto *VDispMap = CGM.getModule().getNamedGlobal(MangledName))
return VDispMap;
MicrosoftVTableContext &VTContext = CGM.getMicrosoftVTableContext();
unsigned NumEntries = 1 + SrcRD->getNumVBases();
SmallVector<llvm::Constant *, 4> Map(NumEntries,
llvm::UndefValue::get(CGM.IntTy));
Map[0] = llvm::ConstantInt::get(CGM.IntTy, 0);
bool AnyDifferent = false;
for (const auto &I : SrcRD->vbases()) {
const CXXRecordDecl *VBase = I.getType()->getAsCXXRecordDecl();
if (!DstRD->isVirtuallyDerivedFrom(VBase))
continue;
unsigned SrcVBIndex = VTContext.getVBTableIndex(SrcRD, VBase);
unsigned DstVBIndex = VTContext.getVBTableIndex(DstRD, VBase);
Map[SrcVBIndex] = llvm::ConstantInt::get(CGM.IntTy, DstVBIndex * 4);
AnyDifferent |= SrcVBIndex != DstVBIndex;
}
// This map would be useless, don't use it.
if (!AnyDifferent)
return nullptr;
llvm::ArrayType *VDispMapTy = llvm::ArrayType::get(CGM.IntTy, Map.size());
llvm::Constant *Init = llvm::ConstantArray::get(VDispMapTy, Map);
llvm::GlobalValue::LinkageTypes Linkage =
SrcRD->isExternallyVisible() && DstRD->isExternallyVisible()
? llvm::GlobalValue::LinkOnceODRLinkage
: llvm::GlobalValue::InternalLinkage;
auto *VDispMap = new llvm::GlobalVariable(
CGM.getModule(), VDispMapTy, /*Constant=*/true, Linkage,
/*Initializer=*/Init, MangledName);
return VDispMap;
}
void emitVBTableDefinition(const VPtrInfo &VBT, const CXXRecordDecl *RD,
llvm::GlobalVariable *GV) const;
void setThunkLinkage(llvm::Function *Thunk, bool ForVTable,
GlobalDecl GD, bool ReturnAdjustment) override {
// Never dllimport/dllexport thunks.
Thunk->setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass);
GVALinkage Linkage =
getContext().GetGVALinkageForFunction(cast<FunctionDecl>(GD.getDecl()));
if (Linkage == GVA_Internal)
Thunk->setLinkage(llvm::GlobalValue::InternalLinkage);
else if (ReturnAdjustment)
Thunk->setLinkage(llvm::GlobalValue::WeakODRLinkage);
else
Thunk->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage);
}
llvm::Value *performThisAdjustment(CodeGenFunction &CGF, Address This,
const ThisAdjustment &TA) override;
llvm::Value *performReturnAdjustment(CodeGenFunction &CGF, Address Ret,
const ReturnAdjustment &RA) override;
void EmitThreadLocalInitFuncs(
CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals,
ArrayRef<llvm::Function *> CXXThreadLocalInits,
ArrayRef<const VarDecl *> CXXThreadLocalInitVars) override;
bool usesThreadWrapperFunction() const override { return false; }
LValue EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF, const VarDecl *VD,
QualType LValType) override;
void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
llvm::GlobalVariable *DeclPtr,
bool PerformInit) override;
void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,
llvm::Constant *Dtor, llvm::Constant *Addr) override;
// ==== Notes on array cookies =========
//
// MSVC seems to only use cookies when the class has a destructor; a
// two-argument usual array deallocation function isn't sufficient.
//
// For example, this code prints "100" and "1":
// struct A {
// char x;
// void *operator new[](size_t sz) {
// printf("%u\n", sz);
// return malloc(sz);
// }
// void operator delete[](void *p, size_t sz) {
// printf("%u\n", sz);
// free(p);
// }
// };
// int main() {
// A *p = new A[100];
// delete[] p;
// }
// Whereas it prints "104" and "104" if you give A a destructor.
bool requiresArrayCookie(const CXXDeleteExpr *expr,
QualType elementType) override;
bool requiresArrayCookie(const CXXNewExpr *expr) override;
CharUnits getArrayCookieSizeImpl(QualType type) override;
Address InitializeArrayCookie(CodeGenFunction &CGF,
Address NewPtr,
llvm::Value *NumElements,
const CXXNewExpr *expr,
QualType ElementType) override;
llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF,
Address allocPtr,
CharUnits cookieSize) override;
friend struct MSRTTIBuilder;
bool isImageRelative() const {
return CGM.getTarget().getPointerWidth(/*AddressSpace=*/0) == 64;
}
// 5 routines for constructing the llvm types for MS RTTI structs.
llvm::StructType *getTypeDescriptorType(StringRef TypeInfoString) {
llvm::SmallString<32> TDTypeName("rtti.TypeDescriptor");
TDTypeName += llvm::utostr(TypeInfoString.size());
llvm::StructType *&TypeDescriptorType =
TypeDescriptorTypeMap[TypeInfoString.size()];
if (TypeDescriptorType)
return TypeDescriptorType;
llvm::Type *FieldTypes[] = {
CGM.Int8PtrPtrTy,
CGM.Int8PtrTy,
llvm::ArrayType::get(CGM.Int8Ty, TypeInfoString.size() + 1)};
TypeDescriptorType =
llvm::StructType::create(CGM.getLLVMContext(), FieldTypes, TDTypeName);
return TypeDescriptorType;
}
llvm::Type *getImageRelativeType(llvm::Type *PtrType) {
if (!isImageRelative())
return PtrType;
return CGM.IntTy;
}
llvm::StructType *getBaseClassDescriptorType() {
if (BaseClassDescriptorType)
return BaseClassDescriptorType;
llvm::Type *FieldTypes[] = {
getImageRelativeType(CGM.Int8PtrTy),
CGM.IntTy,
CGM.IntTy,
CGM.IntTy,
CGM.IntTy,
CGM.IntTy,
getImageRelativeType(getClassHierarchyDescriptorType()->getPointerTo()),
};
BaseClassDescriptorType = llvm::StructType::create(
CGM.getLLVMContext(), FieldTypes, "rtti.BaseClassDescriptor");
return BaseClassDescriptorType;
}
llvm::StructType *getClassHierarchyDescriptorType() {
if (ClassHierarchyDescriptorType)
return ClassHierarchyDescriptorType;
// Forward-declare RTTIClassHierarchyDescriptor to break a cycle.
ClassHierarchyDescriptorType = llvm::StructType::create(
CGM.getLLVMContext(), "rtti.ClassHierarchyDescriptor");
llvm::Type *FieldTypes[] = {
CGM.IntTy,
CGM.IntTy,
CGM.IntTy,
getImageRelativeType(
getBaseClassDescriptorType()->getPointerTo()->getPointerTo()),
};
ClassHierarchyDescriptorType->setBody(FieldTypes);
return ClassHierarchyDescriptorType;
}
llvm::StructType *getCompleteObjectLocatorType() {
if (CompleteObjectLocatorType)
return CompleteObjectLocatorType;
CompleteObjectLocatorType = llvm::StructType::create(
CGM.getLLVMContext(), "rtti.CompleteObjectLocator");
llvm::Type *FieldTypes[] = {
CGM.IntTy,
CGM.IntTy,
CGM.IntTy,
getImageRelativeType(CGM.Int8PtrTy),
getImageRelativeType(getClassHierarchyDescriptorType()->getPointerTo()),
getImageRelativeType(CompleteObjectLocatorType),
};
llvm::ArrayRef<llvm::Type *> FieldTypesRef(FieldTypes);
if (!isImageRelative())
FieldTypesRef = FieldTypesRef.drop_back();
CompleteObjectLocatorType->setBody(FieldTypesRef);
return CompleteObjectLocatorType;
}
llvm::GlobalVariable *getImageBase() {
StringRef Name = "__ImageBase";
if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(Name))
return GV;
return new llvm::GlobalVariable(CGM.getModule(), CGM.Int8Ty,
/*isConstant=*/true,
llvm::GlobalValue::ExternalLinkage,
/*Initializer=*/nullptr, Name);
}
llvm::Constant *getImageRelativeConstant(llvm::Constant *PtrVal) {
if (!isImageRelative())
return PtrVal;
if (PtrVal->isNullValue())
return llvm::Constant::getNullValue(CGM.IntTy);
llvm::Constant *ImageBaseAsInt =
llvm::ConstantExpr::getPtrToInt(getImageBase(), CGM.IntPtrTy);
llvm::Constant *PtrValAsInt =
llvm::ConstantExpr::getPtrToInt(PtrVal, CGM.IntPtrTy);
llvm::Constant *Diff =
llvm::ConstantExpr::getSub(PtrValAsInt, ImageBaseAsInt,
/*HasNUW=*/true, /*HasNSW=*/true);
return llvm::ConstantExpr::getTrunc(Diff, CGM.IntTy);
}
private:
MicrosoftMangleContext &getMangleContext() {
return cast<MicrosoftMangleContext>(CodeGen::CGCXXABI::getMangleContext());
}
llvm::Constant *getZeroInt() {
return llvm::ConstantInt::get(CGM.IntTy, 0);
}
llvm::Constant *getAllOnesInt() {
return llvm::Constant::getAllOnesValue(CGM.IntTy);
}
CharUnits getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) override;
void
GetNullMemberPointerFields(const MemberPointerType *MPT,
llvm::SmallVectorImpl<llvm::Constant *> &fields);
/// \brief Shared code for virtual base adjustment. Returns the offset from
/// the vbptr to the virtual base. Optionally returns the address of the
/// vbptr itself.
llvm::Value *GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,
Address Base,
llvm::Value *VBPtrOffset,
llvm::Value *VBTableOffset,
llvm::Value **VBPtr = nullptr);
llvm::Value *GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,
Address Base,
int32_t VBPtrOffset,
int32_t VBTableOffset,
llvm::Value **VBPtr = nullptr) {
assert(VBTableOffset % 4 == 0 && "should be byte offset into table of i32s");
llvm::Value *VBPOffset = llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset),
*VBTOffset = llvm::ConstantInt::get(CGM.IntTy, VBTableOffset);
return GetVBaseOffsetFromVBPtr(CGF, Base, VBPOffset, VBTOffset, VBPtr);
}
std::pair<Address, llvm::Value *>
performBaseAdjustment(CodeGenFunction &CGF, Address Value,
QualType SrcRecordTy);
/// \brief Performs a full virtual base adjustment. Used to dereference
/// pointers to members of virtual bases.
llvm::Value *AdjustVirtualBase(CodeGenFunction &CGF, const Expr *E,
const CXXRecordDecl *RD, Address Base,
llvm::Value *VirtualBaseAdjustmentOffset,
llvm::Value *VBPtrOffset /* optional */);
/// \brief Emits a full member pointer with the fields common to data and
/// function member pointers.
llvm::Constant *EmitFullMemberPointer(llvm::Constant *FirstField,
bool IsMemberFunction,
const CXXRecordDecl *RD,
CharUnits NonVirtualBaseAdjustment,
unsigned VBTableIndex);
bool MemberPointerConstantIsNull(const MemberPointerType *MPT,
llvm::Constant *MP);
/// \brief - Initialize all vbptrs of 'this' with RD as the complete type.
void EmitVBPtrStores(CodeGenFunction &CGF, const CXXRecordDecl *RD);
/// \brief Caching wrapper around VBTableBuilder::enumerateVBTables().
const VBTableGlobals &enumerateVBTables(const CXXRecordDecl *RD);
/// \brief Generate a thunk for calling a virtual member function MD.
llvm::Function *EmitVirtualMemPtrThunk(
const CXXMethodDecl *MD,
const MicrosoftVTableContext::MethodVFTableLocation &ML);
public:
llvm::Type *ConvertMemberPointerType(const MemberPointerType *MPT) override;
bool isZeroInitializable(const MemberPointerType *MPT) override;
bool isMemberPointerConvertible(const MemberPointerType *MPT) const override {
const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
return RD->hasAttr<MSInheritanceAttr>();
}
llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT) override;
llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,
CharUnits offset) override;
llvm::Constant *EmitMemberFunctionPointer(const CXXMethodDecl *MD) override;
llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT) override;
llvm::Value *EmitMemberPointerComparison(CodeGenFunction &CGF,
llvm::Value *L,
llvm::Value *R,
const MemberPointerType *MPT,
bool Inequality) override;
llvm::Value *EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
llvm::Value *MemPtr,
const MemberPointerType *MPT) override;
llvm::Value *
EmitMemberDataPointerAddress(CodeGenFunction &CGF, const Expr *E,
Address Base, llvm::Value *MemPtr,
const MemberPointerType *MPT) override;
llvm::Value *EmitNonNullMemberPointerConversion(
const MemberPointerType *SrcTy, const MemberPointerType *DstTy,
CastKind CK, CastExpr::path_const_iterator PathBegin,
CastExpr::path_const_iterator PathEnd, llvm::Value *Src,
CGBuilderTy &Builder);
llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,
const CastExpr *E,
llvm::Value *Src) override;
llvm::Constant *EmitMemberPointerConversion(const CastExpr *E,
llvm::Constant *Src) override;
llvm::Constant *EmitMemberPointerConversion(
const MemberPointerType *SrcTy, const MemberPointerType *DstTy,
CastKind CK, CastExpr::path_const_iterator PathBegin,
CastExpr::path_const_iterator PathEnd, llvm::Constant *Src);
CGCallee
EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, const Expr *E,
Address This, llvm::Value *&ThisPtrForCall,
llvm::Value *MemPtr,
const MemberPointerType *MPT) override;
void emitCXXStructor(const CXXMethodDecl *MD, StructorType Type) override;
llvm::StructType *getCatchableTypeType() {
if (CatchableTypeType)
return CatchableTypeType;
llvm::Type *FieldTypes[] = {
CGM.IntTy, // Flags
getImageRelativeType(CGM.Int8PtrTy), // TypeDescriptor
CGM.IntTy, // NonVirtualAdjustment
CGM.IntTy, // OffsetToVBPtr
CGM.IntTy, // VBTableIndex
CGM.IntTy, // Size
getImageRelativeType(CGM.Int8PtrTy) // CopyCtor
};
CatchableTypeType = llvm::StructType::create(
CGM.getLLVMContext(), FieldTypes, "eh.CatchableType");
return CatchableTypeType;
}
llvm::StructType *getCatchableTypeArrayType(uint32_t NumEntries) {
llvm::StructType *&CatchableTypeArrayType =
CatchableTypeArrayTypeMap[NumEntries];
if (CatchableTypeArrayType)
return CatchableTypeArrayType;
llvm::SmallString<23> CTATypeName("eh.CatchableTypeArray.");
CTATypeName += llvm::utostr(NumEntries);
llvm::Type *CTType =
getImageRelativeType(getCatchableTypeType()->getPointerTo());
llvm::Type *FieldTypes[] = {
CGM.IntTy, // NumEntries
llvm::ArrayType::get(CTType, NumEntries) // CatchableTypes
};
CatchableTypeArrayType =
llvm::StructType::create(CGM.getLLVMContext(), FieldTypes, CTATypeName);
return CatchableTypeArrayType;
}
llvm::StructType *getThrowInfoType() {
if (ThrowInfoType)
return ThrowInfoType;
llvm::Type *FieldTypes[] = {
CGM.IntTy, // Flags
getImageRelativeType(CGM.Int8PtrTy), // CleanupFn
getImageRelativeType(CGM.Int8PtrTy), // ForwardCompat
getImageRelativeType(CGM.Int8PtrTy) // CatchableTypeArray
};
ThrowInfoType = llvm::StructType::create(CGM.getLLVMContext(), FieldTypes,
"eh.ThrowInfo");
return ThrowInfoType;
}
llvm::Constant *getThrowFn() {
// _CxxThrowException is passed an exception object and a ThrowInfo object
// which describes the exception.
llvm::Type *Args[] = {CGM.Int8PtrTy, getThrowInfoType()->getPointerTo()};
llvm::FunctionType *FTy =
llvm::FunctionType::get(CGM.VoidTy, Args, /*IsVarArgs=*/false);
auto *Fn = cast<llvm::Function>(
CGM.CreateRuntimeFunction(FTy, "_CxxThrowException"));
// _CxxThrowException is stdcall on 32-bit x86 platforms.
if (CGM.getTarget().getTriple().getArch() == llvm::Triple::x86)
Fn->setCallingConv(llvm::CallingConv::X86_StdCall);
return Fn;
}
llvm::Function *getAddrOfCXXCtorClosure(const CXXConstructorDecl *CD,
CXXCtorType CT);
llvm::Constant *getCatchableType(QualType T,
uint32_t NVOffset = 0,
int32_t VBPtrOffset = -1,
uint32_t VBIndex = 0);
llvm::GlobalVariable *getCatchableTypeArray(QualType T);
llvm::GlobalVariable *getThrowInfo(QualType T) override;
private:
typedef std::pair<const CXXRecordDecl *, CharUnits> VFTableIdTy;
typedef llvm::DenseMap<VFTableIdTy, llvm::GlobalVariable *> VTablesMapTy;
typedef llvm::DenseMap<VFTableIdTy, llvm::GlobalValue *> VFTablesMapTy;
/// \brief All the vftables that have been referenced.
VFTablesMapTy VFTablesMap;
VTablesMapTy VTablesMap;
/// \brief This set holds the record decls we've deferred vtable emission for.
llvm::SmallPtrSet<const CXXRecordDecl *, 4> DeferredVFTables;
/// \brief All the vbtables which have been referenced.
llvm::DenseMap<const CXXRecordDecl *, VBTableGlobals> VBTablesMap;
/// Info on the global variable used to guard initialization of static locals.
/// The BitIndex field is only used for externally invisible declarations.
struct GuardInfo {
GuardInfo() : Guard(nullptr), BitIndex(0) {}
llvm::GlobalVariable *Guard;
unsigned BitIndex;
};
/// Map from DeclContext to the current guard variable. We assume that the
/// AST is visited in source code order.
llvm::DenseMap<const DeclContext *, GuardInfo> GuardVariableMap;
llvm::DenseMap<const DeclContext *, GuardInfo> ThreadLocalGuardVariableMap;
llvm::DenseMap<const DeclContext *, unsigned> ThreadSafeGuardNumMap;
llvm::DenseMap<size_t, llvm::StructType *> TypeDescriptorTypeMap;
llvm::StructType *BaseClassDescriptorType;
llvm::StructType *ClassHierarchyDescriptorType;
llvm::StructType *CompleteObjectLocatorType;
llvm::DenseMap<QualType, llvm::GlobalVariable *> CatchableTypeArrays;
llvm::StructType *CatchableTypeType;
llvm::DenseMap<uint32_t, llvm::StructType *> CatchableTypeArrayTypeMap;
llvm::StructType *ThrowInfoType;
};
}
CGCXXABI::RecordArgABI
MicrosoftCXXABI::getRecordArgABI(const CXXRecordDecl *RD) const {
switch (CGM.getTarget().getTriple().getArch()) {
default:
// FIXME: Implement for other architectures.
return RAA_Default;
case llvm::Triple::thumb:
// Use the simple Itanium rules for now.
// FIXME: This is incompatible with MSVC for arguments with a dtor and no
// copy ctor.
return !canCopyArgument(RD) ? RAA_Indirect : RAA_Default;
case llvm::Triple::x86:
// All record arguments are passed in memory on x86. Decide whether to
// construct the object directly in argument memory, or to construct the
// argument elsewhere and copy the bytes during the call.
// If C++ prohibits us from making a copy, construct the arguments directly
// into argument memory.
if (!canCopyArgument(RD))
return RAA_DirectInMemory;
// Otherwise, construct the argument into a temporary and copy the bytes
// into the outgoing argument memory.
return RAA_Default;
case llvm::Triple::x86_64:
// Win64 passes objects with non-trivial copy ctors indirectly.
if (RD->hasNonTrivialCopyConstructor())
return RAA_Indirect;
// If an object has a destructor, we'd really like to pass it indirectly
// because it allows us to elide copies. Unfortunately, MSVC makes that
// impossible for small types, which it will pass in a single register or
// stack slot. Most objects with dtors are large-ish, so handle that early.
// We can't call out all large objects as being indirect because there are
// multiple x64 calling conventions and the C++ ABI code shouldn't dictate
// how we pass large POD types.
if (RD->hasNonTrivialDestructor() &&
getContext().getTypeSize(RD->getTypeForDecl()) > 64)
return RAA_Indirect;
// If this is true, the implicit copy constructor that Sema would have
// created would not be deleted. FIXME: We should provide a more direct way
// for CodeGen to ask whether the constructor was deleted.
if (!RD->hasUserDeclaredCopyConstructor() &&
!RD->hasUserDeclaredMoveConstructor() &&
!RD->needsOverloadResolutionForMoveConstructor() &&
!RD->hasUserDeclaredMoveAssignment() &&
!RD->needsOverloadResolutionForMoveAssignment())
return RAA_Default;
// Otherwise, Sema should have created an implicit copy constructor if
// needed.
assert(!RD->needsImplicitCopyConstructor());
// We have to make sure the trivial copy constructor isn't deleted.
for (const CXXConstructorDecl *CD : RD->ctors()) {
if (CD->isCopyConstructor()) {
assert(CD->isTrivial());
// We had at least one undeleted trivial copy ctor. Return directly.
if (!CD->isDeleted())
return RAA_Default;
}
}
// The trivial copy constructor was deleted. Return indirectly.
return RAA_Indirect;
}
llvm_unreachable("invalid enum");
}
void MicrosoftCXXABI::emitVirtualObjectDelete(CodeGenFunction &CGF,
const CXXDeleteExpr *DE,
Address Ptr,
QualType ElementType,
const CXXDestructorDecl *Dtor) {
// FIXME: Provide a source location here even though there's no
// CXXMemberCallExpr for dtor call.
bool UseGlobalDelete = DE->isGlobalDelete();
CXXDtorType DtorType = UseGlobalDelete ? Dtor_Complete : Dtor_Deleting;
llvm::Value *MDThis =
EmitVirtualDestructorCall(CGF, Dtor, DtorType, Ptr, /*CE=*/nullptr);
if (UseGlobalDelete)
CGF.EmitDeleteCall(DE->getOperatorDelete(), MDThis, ElementType);
}
void MicrosoftCXXABI::emitRethrow(CodeGenFunction &CGF, bool isNoReturn) {
llvm::Value *Args[] = {
llvm::ConstantPointerNull::get(CGM.Int8PtrTy),
llvm::ConstantPointerNull::get(getThrowInfoType()->getPointerTo())};
auto *Fn = getThrowFn();
if (isNoReturn)
CGF.EmitNoreturnRuntimeCallOrInvoke(Fn, Args);
else
CGF.EmitRuntimeCallOrInvoke(Fn, Args);
}
namespace {
struct CatchRetScope final : EHScopeStack::Cleanup {
llvm::CatchPadInst *CPI;
CatchRetScope(llvm::CatchPadInst *CPI) : CPI(CPI) {}
void Emit(CodeGenFunction &CGF, Flags flags) override {
llvm::BasicBlock *BB = CGF.createBasicBlock("catchret.dest");
CGF.Builder.CreateCatchRet(CPI, BB);
CGF.EmitBlock(BB);
}
};
}
void MicrosoftCXXABI::emitBeginCatch(CodeGenFunction &CGF,
const CXXCatchStmt *S) {
// In the MS ABI, the runtime handles the copy, and the catch handler is
// responsible for destruction.
VarDecl *CatchParam = S->getExceptionDecl();
llvm::BasicBlock *CatchPadBB = CGF.Builder.GetInsertBlock();
llvm::CatchPadInst *CPI =
cast<llvm::CatchPadInst>(CatchPadBB->getFirstNonPHI());
CGF.CurrentFuncletPad = CPI;
// If this is a catch-all or the catch parameter is unnamed, we don't need to
// emit an alloca to the object.
if (!CatchParam || !CatchParam->getDeclName()) {
CGF.EHStack.pushCleanup<CatchRetScope>(NormalCleanup, CPI);
return;
}
CodeGenFunction::AutoVarEmission var = CGF.EmitAutoVarAlloca(*CatchParam);
CPI->setArgOperand(2, var.getObjectAddress(CGF).getPointer());
CGF.EHStack.pushCleanup<CatchRetScope>(NormalCleanup, CPI);
CGF.EmitAutoVarCleanups(var);
}
/// We need to perform a generic polymorphic operation (like a typeid
/// or a cast), which requires an object with a vfptr. Adjust the
/// address to point to an object with a vfptr.
std::pair<Address, llvm::Value *>
MicrosoftCXXABI::performBaseAdjustment(CodeGenFunction &CGF, Address Value,
QualType SrcRecordTy) {
Value = CGF.Builder.CreateBitCast(Value, CGF.Int8PtrTy);
const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();
const ASTContext &Context = getContext();
// If the class itself has a vfptr, great. This check implicitly
// covers non-virtual base subobjects: a class with its own virtual
// functions would be a candidate to be a primary base.
if (Context.getASTRecordLayout(SrcDecl).hasExtendableVFPtr())
return std::make_pair(Value, llvm::ConstantInt::get(CGF.Int32Ty, 0));
// Okay, one of the vbases must have a vfptr, or else this isn't
// actually a polymorphic class.
const CXXRecordDecl *PolymorphicBase = nullptr;
for (auto &Base : SrcDecl->vbases()) {
const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
if (Context.getASTRecordLayout(BaseDecl).hasExtendableVFPtr()) {
PolymorphicBase = BaseDecl;
break;
}
}
assert(PolymorphicBase && "polymorphic class has no apparent vfptr?");
llvm::Value *Offset =
GetVirtualBaseClassOffset(CGF, Value, SrcDecl, PolymorphicBase);
llvm::Value *Ptr = CGF.Builder.CreateInBoundsGEP(Value.getPointer(), Offset);
CharUnits VBaseAlign =
CGF.CGM.getVBaseAlignment(Value.getAlignment(), SrcDecl, PolymorphicBase);
return std::make_pair(Address(Ptr, VBaseAlign), Offset);
}
bool MicrosoftCXXABI::shouldTypeidBeNullChecked(bool IsDeref,
QualType SrcRecordTy) {
const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();
return IsDeref &&
!getContext().getASTRecordLayout(SrcDecl).hasExtendableVFPtr();
}
static llvm::CallSite emitRTtypeidCall(CodeGenFunction &CGF,
llvm::Value *Argument) {
llvm::Type *ArgTypes[] = {CGF.Int8PtrTy};
llvm::FunctionType *FTy =
llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false);
llvm::Value *Args[] = {Argument};
llvm::Constant *Fn = CGF.CGM.CreateRuntimeFunction(FTy, "__RTtypeid");
return CGF.EmitRuntimeCallOrInvoke(Fn, Args);
}
void MicrosoftCXXABI::EmitBadTypeidCall(CodeGenFunction &CGF) {
llvm::CallSite Call =
emitRTtypeidCall(CGF, llvm::Constant::getNullValue(CGM.VoidPtrTy));
Call.setDoesNotReturn();
CGF.Builder.CreateUnreachable();
}
llvm::Value *MicrosoftCXXABI::EmitTypeid(CodeGenFunction &CGF,
QualType SrcRecordTy,
Address ThisPtr,
llvm::Type *StdTypeInfoPtrTy) {
std::tie(ThisPtr, std::ignore) =
performBaseAdjustment(CGF, ThisPtr, SrcRecordTy);
auto Typeid = emitRTtypeidCall(CGF, ThisPtr.getPointer()).getInstruction();
return CGF.Builder.CreateBitCast(Typeid, StdTypeInfoPtrTy);
}