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llvm-project/clang/lib/CodeGen/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 "CodeGenModule.h"
#include "CGVTables.h"
#include "MicrosoftVBTables.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/VTableBuilder.h"
using namespace clang;
using namespace CodeGen;
namespace {
class MicrosoftCXXABI : public CGCXXABI {
public:
MicrosoftCXXABI(CodeGenModule &CGM) : CGCXXABI(CGM) {}
bool HasThisReturn(GlobalDecl GD) const;
bool isReturnTypeIndirect(const CXXRecordDecl *RD) const {
// Structures that are not C++03 PODs are always indirect.
return !RD->isPOD();
}
RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const {
if (RD->hasNonTrivialCopyConstructor() || RD->hasNonTrivialDestructor())
return RAA_DirectInMemory;
return RAA_Default;
}
StringRef GetPureVirtualCallName() { return "_purecall"; }
// No known support for deleted functions in MSVC yet, so this choice is
// arbitrary.
StringRef GetDeletedVirtualCallName() { return "_purecall"; }
llvm::Value *adjustToCompleteObject(CodeGenFunction &CGF,
llvm::Value *ptr,
QualType type);
llvm::Value *GetVirtualBaseClassOffset(CodeGenFunction &CGF,
llvm::Value *This,
const CXXRecordDecl *ClassDecl,
const CXXRecordDecl *BaseClassDecl);
void BuildConstructorSignature(const CXXConstructorDecl *Ctor,
CXXCtorType Type,
CanQualType &ResTy,
SmallVectorImpl<CanQualType> &ArgTys);
llvm::BasicBlock *EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
const CXXRecordDecl *RD);
void EmitCXXConstructors(const CXXConstructorDecl *D);
// 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.
void BuildDestructorSignature(const CXXDestructorDecl *Dtor,
CXXDtorType Type,
CanQualType &ResTy,
SmallVectorImpl<CanQualType> &ArgTys);
/// Non-base dtors should be emitted as delegating thunks in this ABI.
bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor,
CXXDtorType DT) const {
return DT != Dtor_Base;
}
void EmitCXXDestructors(const CXXDestructorDecl *D);
void BuildInstanceFunctionParams(CodeGenFunction &CGF,
QualType &ResTy,
FunctionArgList &Params);
void EmitInstanceFunctionProlog(CodeGenFunction &CGF);
void EmitConstructorCall(CodeGenFunction &CGF,
const CXXConstructorDecl *D, CXXCtorType Type,
bool ForVirtualBase, bool Delegating,
llvm::Value *This,
CallExpr::const_arg_iterator ArgBeg,
CallExpr::const_arg_iterator ArgEnd);
void EmitVirtualDestructorCall(CodeGenFunction &CGF,
const CXXDestructorDecl *Dtor,
CXXDtorType DtorType, SourceLocation CallLoc,
llvm::Value *This);
void EmitVirtualInheritanceTables(llvm::GlobalVariable::LinkageTypes Linkage,
const CXXRecordDecl *RD);
void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
llvm::GlobalVariable *DeclPtr,
bool PerformInit);
// ==== 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);
bool requiresArrayCookie(const CXXNewExpr *expr);
CharUnits getArrayCookieSizeImpl(QualType type);
llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF,
llvm::Value *NewPtr,
llvm::Value *NumElements,
const CXXNewExpr *expr,
QualType ElementType);
llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF,
llvm::Value *allocPtr,
CharUnits cookieSize);
private:
llvm::Constant *getZeroInt() {
return llvm::ConstantInt::get(CGM.IntTy, 0);
}
llvm::Constant *getAllOnesInt() {
return llvm::Constant::getAllOnesValue(CGM.IntTy);
}
llvm::Constant *getConstantOrZeroInt(llvm::Constant *C) {
return C ? C : getZeroInt();
}
llvm::Value *getValueOrZeroInt(llvm::Value *C) {
return C ? C : getZeroInt();
}
void
GetNullMemberPointerFields(const MemberPointerType *MPT,
llvm::SmallVectorImpl<llvm::Constant *> &fields);
/// \brief Finds the offset from the base of RD to the vbptr it uses, even if
/// it is reusing a vbptr from a non-virtual base. RD must have morally
/// virtual bases.
CharUnits GetVBPtrOffsetFromBases(const CXXRecordDecl *RD);
/// \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,
llvm::Value *Base,
llvm::Value *VBPtrOffset,
llvm::Value *VBTableOffset,
llvm::Value **VBPtr = 0);
/// \brief Performs a full virtual base adjustment. Used to dereference
/// pointers to members of virtual bases.
llvm::Value *AdjustVirtualBase(CodeGenFunction &CGF, const CXXRecordDecl *RD,
llvm::Value *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);
llvm::Constant *BuildMemberPointer(const CXXRecordDecl *RD,
const CXXMethodDecl *MD,
CharUnits NonVirtualBaseAdjustment);
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 VBTableVector &EnumerateVBTables(const CXXRecordDecl *RD);
public:
virtual llvm::Type *ConvertMemberPointerType(const MemberPointerType *MPT);
virtual bool isZeroInitializable(const MemberPointerType *MPT);
virtual llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT);
virtual llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,
CharUnits offset);
virtual llvm::Constant *EmitMemberPointer(const CXXMethodDecl *MD);
virtual llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT);
virtual llvm::Value *EmitMemberPointerComparison(CodeGenFunction &CGF,
llvm::Value *L,
llvm::Value *R,
const MemberPointerType *MPT,
bool Inequality);
virtual llvm::Value *EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
llvm::Value *MemPtr,
const MemberPointerType *MPT);
virtual llvm::Value *EmitMemberDataPointerAddress(CodeGenFunction &CGF,
llvm::Value *Base,
llvm::Value *MemPtr,
const MemberPointerType *MPT);
virtual llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,
const CastExpr *E,
llvm::Value *Src);
virtual llvm::Constant *EmitMemberPointerConversion(const CastExpr *E,
llvm::Constant *Src);
virtual llvm::Value *
EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF,
llvm::Value *&This,
llvm::Value *MemPtr,
const MemberPointerType *MPT);
private:
/// VBTables - All the vbtables which have been referenced.
llvm::DenseMap<const CXXRecordDecl *, VBTableVector> VBTablesMap;
};
}
llvm::Value *MicrosoftCXXABI::adjustToCompleteObject(CodeGenFunction &CGF,
llvm::Value *ptr,
QualType type) {
// FIXME: implement
return ptr;
}
/// \brief Finds the first non-virtual base of RD that has virtual bases. If RD
/// doesn't have a vbptr, it will reuse the vbptr of the returned class.
static const CXXRecordDecl *FindFirstNVBaseWithVBases(const CXXRecordDecl *RD) {
for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
E = RD->bases_end(); I != E; ++I) {
const CXXRecordDecl *Base = I->getType()->getAsCXXRecordDecl();
if (!I->isVirtual() && Base->getNumVBases() > 0)
return Base;
}
llvm_unreachable("RD must have an nv base with vbases");
}
CharUnits MicrosoftCXXABI::GetVBPtrOffsetFromBases(const CXXRecordDecl *RD) {
assert(RD->getNumVBases());
CharUnits Total = CharUnits::Zero();
while (RD) {
const ASTRecordLayout &RDLayout = getContext().getASTRecordLayout(RD);
CharUnits VBPtrOffset = RDLayout.getVBPtrOffset();
// -1 is the sentinel for no vbptr.
if (VBPtrOffset != CharUnits::fromQuantity(-1)) {
Total += VBPtrOffset;
break;
}
RD = FindFirstNVBaseWithVBases(RD);
Total += RDLayout.getBaseClassOffset(RD);
}
return Total;
}
llvm::Value *
MicrosoftCXXABI::GetVirtualBaseClassOffset(CodeGenFunction &CGF,
llvm::Value *This,
const CXXRecordDecl *ClassDecl,
const CXXRecordDecl *BaseClassDecl) {
int64_t VBPtrChars = GetVBPtrOffsetFromBases(ClassDecl).getQuantity();
llvm::Value *VBPtrOffset = llvm::ConstantInt::get(CGM.PtrDiffTy, VBPtrChars);
CharUnits IntSize = getContext().getTypeSizeInChars(getContext().IntTy);
CharUnits VBTableChars = IntSize * GetVBTableIndex(ClassDecl, BaseClassDecl);
llvm::Value *VBTableOffset =
llvm::ConstantInt::get(CGM.IntTy, VBTableChars.getQuantity());
llvm::Value *VBPtrToNewBase =
GetVBaseOffsetFromVBPtr(CGF, This, VBTableOffset, VBPtrOffset);
VBPtrToNewBase =
CGF.Builder.CreateSExtOrBitCast(VBPtrToNewBase, CGM.PtrDiffTy);
return CGF.Builder.CreateNSWAdd(VBPtrOffset, VBPtrToNewBase);
}
bool MicrosoftCXXABI::HasThisReturn(GlobalDecl GD) const {
return isa<CXXConstructorDecl>(GD.getDecl());
}
void MicrosoftCXXABI::BuildConstructorSignature(const CXXConstructorDecl *Ctor,
CXXCtorType Type,
CanQualType &ResTy,
SmallVectorImpl<CanQualType> &ArgTys) {
// 'this' parameter and 'this' return are already in place
const CXXRecordDecl *Class = Ctor->getParent();
if (Class->getNumVBases()) {
// Constructors of classes with virtual bases take an implicit parameter.
ArgTys.push_back(CGM.getContext().IntTy);
}
}
llvm::BasicBlock *
MicrosoftCXXABI::EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
const CXXRecordDecl *RD) {
llvm::Value *IsMostDerivedClass = getStructorImplicitParamValue(CGF);
assert(IsMostDerivedClass &&
"ctor for a class with virtual bases must have an implicit parameter");
llvm::Value *IsCompleteObject =
CGF.Builder.CreateIsNotNull(IsMostDerivedClass, "is_complete_object");
llvm::BasicBlock *CallVbaseCtorsBB = CGF.createBasicBlock("ctor.init_vbases");
llvm::BasicBlock *SkipVbaseCtorsBB = CGF.createBasicBlock("ctor.skip_vbases");
CGF.Builder.CreateCondBr(IsCompleteObject,
CallVbaseCtorsBB, SkipVbaseCtorsBB);
CGF.EmitBlock(CallVbaseCtorsBB);
// Fill in the vbtable pointers here.
EmitVBPtrStores(CGF, RD);
// CGF will put the base ctor calls in this basic block for us later.
return SkipVbaseCtorsBB;
}
void MicrosoftCXXABI::EmitCXXConstructors(const CXXConstructorDecl *D) {
// There's only one constructor type in this ABI.
CGM.EmitGlobal(GlobalDecl(D, Ctor_Complete));
}
void MicrosoftCXXABI::EmitVBPtrStores(CodeGenFunction &CGF,
const CXXRecordDecl *RD) {
llvm::Value *ThisInt8Ptr =
CGF.Builder.CreateBitCast(getThisValue(CGF), CGM.Int8PtrTy, "this.int8");
const VBTableVector &VBTables = EnumerateVBTables(RD);
for (VBTableVector::const_iterator I = VBTables.begin(), E = VBTables.end();
I != E; ++I) {
const ASTRecordLayout &SubobjectLayout =
CGM.getContext().getASTRecordLayout(I->VBPtrSubobject.getBase());
uint64_t Offs = (I->VBPtrSubobject.getBaseOffset() +
SubobjectLayout.getVBPtrOffset()).getQuantity();
llvm::Value *VBPtr =
CGF.Builder.CreateConstInBoundsGEP1_64(ThisInt8Ptr, Offs);
VBPtr = CGF.Builder.CreateBitCast(VBPtr, I->GV->getType()->getPointerTo(0),
"vbptr." + I->ReusingBase->getName());
CGF.Builder.CreateStore(I->GV, VBPtr);
}
}
void MicrosoftCXXABI::BuildDestructorSignature(const CXXDestructorDecl *Dtor,
CXXDtorType Type,
CanQualType &ResTy,
SmallVectorImpl<CanQualType> &ArgTys) {
// 'this' is already in place
// TODO: 'for base' flag
if (Type == Dtor_Deleting) {
// The scalar deleting destructor takes an implicit bool parameter.
ArgTys.push_back(CGM.getContext().BoolTy);
}
}
void MicrosoftCXXABI::EmitCXXDestructors(const CXXDestructorDecl *D) {
// The TU defining a dtor is only guaranteed to emit a base destructor. All
// other destructor variants are delegating thunks.
CGM.EmitGlobal(GlobalDecl(D, Dtor_Base));
}
static bool IsDeletingDtor(GlobalDecl GD) {
const CXXMethodDecl* MD = cast<CXXMethodDecl>(GD.getDecl());
if (isa<CXXDestructorDecl>(MD)) {
return GD.getDtorType() == Dtor_Deleting;
}
return false;
}
void MicrosoftCXXABI::BuildInstanceFunctionParams(CodeGenFunction &CGF,
QualType &ResTy,
FunctionArgList &Params) {
BuildThisParam(CGF, Params);
ASTContext &Context = getContext();
const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
if (isa<CXXConstructorDecl>(MD) && MD->getParent()->getNumVBases()) {
ImplicitParamDecl *IsMostDerived
= ImplicitParamDecl::Create(Context, 0,
CGF.CurGD.getDecl()->getLocation(),
&Context.Idents.get("is_most_derived"),
Context.IntTy);
Params.push_back(IsMostDerived);
getStructorImplicitParamDecl(CGF) = IsMostDerived;
} else if (IsDeletingDtor(CGF.CurGD)) {
ImplicitParamDecl *ShouldDelete
= ImplicitParamDecl::Create(Context, 0,
CGF.CurGD.getDecl()->getLocation(),
&Context.Idents.get("should_call_delete"),
Context.BoolTy);
Params.push_back(ShouldDelete);
getStructorImplicitParamDecl(CGF) = ShouldDelete;
}
}
void MicrosoftCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) {
EmitThisParam(CGF);
/// If this is a function that the ABI specifies returns 'this', initialize
/// the return slot to 'this' at the start of the function.
///
/// Unlike the setting of return types, this is done within the ABI
/// implementation instead of by clients of CGCXXABI because:
/// 1) getThisValue is currently protected
/// 2) in theory, an ABI could implement 'this' returns some other way;
/// HasThisReturn only specifies a contract, not the implementation
if (HasThisReturn(CGF.CurGD))
CGF.Builder.CreateStore(getThisValue(CGF), CGF.ReturnValue);
const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
if (isa<CXXConstructorDecl>(MD) && MD->getParent()->getNumVBases()) {
assert(getStructorImplicitParamDecl(CGF) &&
"no implicit parameter for a constructor with virtual bases?");
getStructorImplicitParamValue(CGF)
= CGF.Builder.CreateLoad(
CGF.GetAddrOfLocalVar(getStructorImplicitParamDecl(CGF)),
"is_most_derived");
}
if (IsDeletingDtor(CGF.CurGD)) {
assert(getStructorImplicitParamDecl(CGF) &&
"no implicit parameter for a deleting destructor?");
getStructorImplicitParamValue(CGF)
= CGF.Builder.CreateLoad(
CGF.GetAddrOfLocalVar(getStructorImplicitParamDecl(CGF)),
"should_call_delete");
}
}
void MicrosoftCXXABI::EmitConstructorCall(CodeGenFunction &CGF,
const CXXConstructorDecl *D,
CXXCtorType Type,
bool ForVirtualBase,
bool Delegating,
llvm::Value *This,
CallExpr::const_arg_iterator ArgBeg,
CallExpr::const_arg_iterator ArgEnd) {
assert(Type == Ctor_Complete || Type == Ctor_Base);
llvm::Value *Callee = CGM.GetAddrOfCXXConstructor(D, Ctor_Complete);
llvm::Value *ImplicitParam = 0;
QualType ImplicitParamTy;
if (D->getParent()->getNumVBases()) {
ImplicitParam = llvm::ConstantInt::get(CGM.Int32Ty, Type == Ctor_Complete);
ImplicitParamTy = getContext().IntTy;
}
// FIXME: Provide a source location here.
CGF.EmitCXXMemberCall(D, SourceLocation(), Callee, ReturnValueSlot(), This,
ImplicitParam, ImplicitParamTy, ArgBeg, ArgEnd);
}
void MicrosoftCXXABI::EmitVirtualDestructorCall(CodeGenFunction &CGF,
const CXXDestructorDecl *Dtor,
CXXDtorType DtorType,
SourceLocation CallLoc,
llvm::Value *This) {
assert(DtorType == Dtor_Deleting || DtorType == Dtor_Complete);
// We have only one destructor in the vftable but can get both behaviors
// by passing an implicit bool parameter.
const CGFunctionInfo *FInfo
= &CGM.getTypes().arrangeCXXDestructor(Dtor, Dtor_Deleting);
llvm::Type *Ty = CGF.CGM.getTypes().GetFunctionType(*FInfo);
llvm::Value *Callee
= CGF.BuildVirtualCall(GlobalDecl(Dtor, Dtor_Deleting), This, Ty);
ASTContext &Context = CGF.getContext();
llvm::Value *ImplicitParam
= llvm::ConstantInt::get(llvm::IntegerType::getInt1Ty(CGF.getLLVMContext()),
DtorType == Dtor_Deleting);
CGF.EmitCXXMemberCall(Dtor, CallLoc, Callee, ReturnValueSlot(), This,
ImplicitParam, Context.BoolTy, 0, 0);
}
const VBTableVector &
MicrosoftCXXABI::EnumerateVBTables(const CXXRecordDecl *RD) {
// At this layer, we can key the cache off of a single class, which is much
// easier than caching at the GlobalVariable layer.
llvm::DenseMap<const CXXRecordDecl*, VBTableVector>::iterator I;
bool added;
llvm::tie(I, added) = VBTablesMap.insert(std::make_pair(RD, VBTableVector()));
VBTableVector &VBTables = I->second;
if (!added)
return VBTables;
VBTableBuilder(CGM, RD).enumerateVBTables(VBTables);
return VBTables;
}
void MicrosoftCXXABI::EmitVirtualInheritanceTables(
llvm::GlobalVariable::LinkageTypes Linkage, const CXXRecordDecl *RD) {
const VBTableVector &VBTables = EnumerateVBTables(RD);
for (VBTableVector::const_iterator I = VBTables.begin(), E = VBTables.end();
I != E; ++I) {
I->EmitVBTableDefinition(CGM, RD, Linkage);
}
}
bool MicrosoftCXXABI::requiresArrayCookie(const CXXDeleteExpr *expr,
QualType elementType) {
// Microsoft seems to completely ignore the possibility of a
// two-argument usual deallocation function.
return elementType.isDestructedType();
}
bool MicrosoftCXXABI::requiresArrayCookie(const CXXNewExpr *expr) {
// Microsoft seems to completely ignore the possibility of a
// two-argument usual deallocation function.
return expr->getAllocatedType().isDestructedType();
}
CharUnits MicrosoftCXXABI::getArrayCookieSizeImpl(QualType type) {
// The array cookie is always a size_t; we then pad that out to the
// alignment of the element type.
ASTContext &Ctx = getContext();
return std::max(Ctx.getTypeSizeInChars(Ctx.getSizeType()),
Ctx.getTypeAlignInChars(type));
}
llvm::Value *MicrosoftCXXABI::readArrayCookieImpl(CodeGenFunction &CGF,
llvm::Value *allocPtr,
CharUnits cookieSize) {
unsigned AS = allocPtr->getType()->getPointerAddressSpace();
llvm::Value *numElementsPtr =
CGF.Builder.CreateBitCast(allocPtr, CGF.SizeTy->getPointerTo(AS));
return CGF.Builder.CreateLoad(numElementsPtr);
}
llvm::Value* MicrosoftCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,
llvm::Value *newPtr,
llvm::Value *numElements,
const CXXNewExpr *expr,
QualType elementType) {
assert(requiresArrayCookie(expr));
// The size of the cookie.
CharUnits cookieSize = getArrayCookieSizeImpl(elementType);
// Compute an offset to the cookie.
llvm::Value *cookiePtr = newPtr;
// Write the number of elements into the appropriate slot.
unsigned AS = newPtr->getType()->getPointerAddressSpace();
llvm::Value *numElementsPtr
= CGF.Builder.CreateBitCast(cookiePtr, CGF.SizeTy->getPointerTo(AS));
CGF.Builder.CreateStore(numElements, numElementsPtr);
// Finally, compute a pointer to the actual data buffer by skipping
// over the cookie completely.
return CGF.Builder.CreateConstInBoundsGEP1_64(newPtr,
cookieSize.getQuantity());
}
void MicrosoftCXXABI::EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
llvm::GlobalVariable *DeclPtr,
bool PerformInit) {
// FIXME: this code was only tested for global initialization.
// Not sure whether we want thread-safe static local variables as VS
// doesn't make them thread-safe.
if (D.getTLSKind())
CGM.ErrorUnsupported(&D, "dynamic TLS initialization");
// Emit the initializer and add a global destructor if appropriate.
CGF.EmitCXXGlobalVarDeclInit(D, DeclPtr, PerformInit);
}
// Member pointer helpers.
static bool hasVBPtrOffsetField(MSInheritanceModel Inheritance) {
return Inheritance == MSIM_Unspecified;
}
static bool hasOnlyOneField(bool IsMemberFunction,
MSInheritanceModel Inheritance) {
return Inheritance <= MSIM_SinglePolymorphic ||
(!IsMemberFunction && Inheritance <= MSIM_MultiplePolymorphic);
}
// Only member pointers to functions need a this adjustment, since it can be
// combined with the field offset for data pointers.
static bool hasNonVirtualBaseAdjustmentField(bool IsMemberFunction,
MSInheritanceModel Inheritance) {
return (IsMemberFunction && Inheritance >= MSIM_Multiple);
}
static bool hasVirtualBaseAdjustmentField(MSInheritanceModel Inheritance) {
return Inheritance >= MSIM_Virtual;
}
// Use zero for the field offset of a null data member pointer if we can
// guarantee that zero is not a valid field offset, or if the member pointer has
// multiple fields. Polymorphic classes have a vfptr at offset zero, so we can
// use zero for null. If there are multiple fields, we can use zero even if it
// is a valid field offset because null-ness testing will check the other
// fields.
static bool nullFieldOffsetIsZero(MSInheritanceModel Inheritance) {
return Inheritance != MSIM_Multiple && Inheritance != MSIM_Single;
}
bool MicrosoftCXXABI::isZeroInitializable(const MemberPointerType *MPT) {
// Null-ness for function memptrs only depends on the first field, which is
// the function pointer. The rest don't matter, so we can zero initialize.
if (MPT->isMemberFunctionPointer())
return true;
// The virtual base adjustment field is always -1 for null, so if we have one
// we can't zero initialize. The field offset is sometimes also -1 if 0 is a
// valid field offset.
const CXXRecordDecl *RD = MPT->getClass()->getAsCXXRecordDecl();
MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
return (!hasVirtualBaseAdjustmentField(Inheritance) &&
nullFieldOffsetIsZero(Inheritance));
}
llvm::Type *
MicrosoftCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) {
const CXXRecordDecl *RD = MPT->getClass()->getAsCXXRecordDecl();
MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
llvm::SmallVector<llvm::Type *, 4> fields;
if (MPT->isMemberFunctionPointer())
fields.push_back(CGM.VoidPtrTy); // FunctionPointerOrVirtualThunk
else
fields.push_back(CGM.IntTy); // FieldOffset
if (hasNonVirtualBaseAdjustmentField(MPT->isMemberFunctionPointer(),
Inheritance))
fields.push_back(CGM.IntTy);
if (hasVBPtrOffsetField(Inheritance))
fields.push_back(CGM.IntTy);
if (hasVirtualBaseAdjustmentField(Inheritance))
fields.push_back(CGM.IntTy); // VirtualBaseAdjustmentOffset
if (fields.size() == 1)
return fields[0];
return llvm::StructType::get(CGM.getLLVMContext(), fields);
}
void MicrosoftCXXABI::
GetNullMemberPointerFields(const MemberPointerType *MPT,
llvm::SmallVectorImpl<llvm::Constant *> &fields) {
assert(fields.empty());
const CXXRecordDecl *RD = MPT->getClass()->getAsCXXRecordDecl();
MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
if (MPT->isMemberFunctionPointer()) {
// FunctionPointerOrVirtualThunk
fields.push_back(llvm::Constant::getNullValue(CGM.VoidPtrTy));
} else {
if (nullFieldOffsetIsZero(Inheritance))
fields.push_back(getZeroInt()); // FieldOffset
else
fields.push_back(getAllOnesInt()); // FieldOffset
}
if (hasNonVirtualBaseAdjustmentField(MPT->isMemberFunctionPointer(),
Inheritance))
fields.push_back(getZeroInt());
if (hasVBPtrOffsetField(Inheritance))
fields.push_back(getZeroInt());
if (hasVirtualBaseAdjustmentField(Inheritance))
fields.push_back(getAllOnesInt());
}
llvm::Constant *
MicrosoftCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) {
llvm::SmallVector<llvm::Constant *, 4> fields;
GetNullMemberPointerFields(MPT, fields);
if (fields.size() == 1)
return fields[0];
llvm::Constant *Res = llvm::ConstantStruct::getAnon(fields);
assert(Res->getType() == ConvertMemberPointerType(MPT));
return Res;
}
llvm::Constant *
MicrosoftCXXABI::EmitFullMemberPointer(llvm::Constant *FirstField,
bool IsMemberFunction,
const CXXRecordDecl *RD,
CharUnits NonVirtualBaseAdjustment)
{
MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
// Single inheritance class member pointer are represented as scalars instead
// of aggregates.
if (hasOnlyOneField(IsMemberFunction, Inheritance))
return FirstField;
llvm::SmallVector<llvm::Constant *, 4> fields;
fields.push_back(FirstField);
if (hasNonVirtualBaseAdjustmentField(IsMemberFunction, Inheritance))
fields.push_back(llvm::ConstantInt::get(
CGM.IntTy, NonVirtualBaseAdjustment.getQuantity()));
if (hasVBPtrOffsetField(Inheritance)) {
fields.push_back(llvm::ConstantInt::get(
CGM.IntTy, GetVBPtrOffsetFromBases(RD).getQuantity()));
}
// The rest of the fields are adjusted by conversions to a more derived class.
if (hasVirtualBaseAdjustmentField(Inheritance))
fields.push_back(getZeroInt());
return llvm::ConstantStruct::getAnon(fields);
}
llvm::Constant *
MicrosoftCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT,
CharUnits offset) {
const CXXRecordDecl *RD = MPT->getClass()->getAsCXXRecordDecl();
llvm::Constant *FirstField =
llvm::ConstantInt::get(CGM.IntTy, offset.getQuantity());
return EmitFullMemberPointer(FirstField, /*IsMemberFunction=*/false, RD,
CharUnits::Zero());
}
llvm::Constant *MicrosoftCXXABI::EmitMemberPointer(const CXXMethodDecl *MD) {
return BuildMemberPointer(MD->getParent(), MD, CharUnits::Zero());
}
llvm::Constant *MicrosoftCXXABI::EmitMemberPointer(const APValue &MP,
QualType MPType) {
const MemberPointerType *MPT = MPType->castAs<MemberPointerType>();
const ValueDecl *MPD = MP.getMemberPointerDecl();
if (!MPD)
return EmitNullMemberPointer(MPT);
CharUnits ThisAdjustment = getMemberPointerPathAdjustment(MP);
// FIXME PR15713: Support virtual inheritance paths.
if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MPD))
return BuildMemberPointer(MPT->getClass()->getAsCXXRecordDecl(),
MD, ThisAdjustment);
CharUnits FieldOffset =
getContext().toCharUnitsFromBits(getContext().getFieldOffset(MPD));
return EmitMemberDataPointer(MPT, ThisAdjustment + FieldOffset);
}
llvm::Constant *
MicrosoftCXXABI::BuildMemberPointer(const CXXRecordDecl *RD,
const CXXMethodDecl *MD,
CharUnits NonVirtualBaseAdjustment) {
assert(MD->isInstance() && "Member function must not be static!");
MD = MD->getCanonicalDecl();
CodeGenTypes &Types = CGM.getTypes();
llvm::Constant *FirstField;
if (MD->isVirtual()) {
// FIXME: We have to instantiate a thunk that loads the vftable and jumps to
// the right offset.
FirstField = llvm::Constant::getNullValue(CGM.VoidPtrTy);
} else {
const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>();
llvm::Type *Ty;
// Check whether the function has a computable LLVM signature.
if (Types.isFuncTypeConvertible(FPT)) {
// The function has a computable LLVM signature; use the correct type.
Ty = Types.GetFunctionType(Types.arrangeCXXMethodDeclaration(MD));
} else {
// Use an arbitrary non-function type to tell GetAddrOfFunction that the
// function type is incomplete.
Ty = CGM.PtrDiffTy;
}
FirstField = CGM.GetAddrOfFunction(MD, Ty);
FirstField = llvm::ConstantExpr::getBitCast(FirstField, CGM.VoidPtrTy);
}
// The rest of the fields are common with data member pointers.
return EmitFullMemberPointer(FirstField, /*IsMemberFunction=*/true, RD,
NonVirtualBaseAdjustment);
}
/// Member pointers are the same if they're either bitwise identical *or* both
/// null. Null-ness for function members is determined by the first field,
/// while for data member pointers we must compare all fields.
llvm::Value *
MicrosoftCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF,
llvm::Value *L,
llvm::Value *R,
const MemberPointerType *MPT,
bool Inequality) {
CGBuilderTy &Builder = CGF.Builder;
// Handle != comparisons by switching the sense of all boolean operations.
llvm::ICmpInst::Predicate Eq;
llvm::Instruction::BinaryOps And, Or;
if (Inequality) {
Eq = llvm::ICmpInst::ICMP_NE;
And = llvm::Instruction::Or;
Or = llvm::Instruction::And;
} else {
Eq = llvm::ICmpInst::ICMP_EQ;
And = llvm::Instruction::And;
Or = llvm::Instruction::Or;
}
// If this is a single field member pointer (single inheritance), this is a
// single icmp.
const CXXRecordDecl *RD = MPT->getClass()->getAsCXXRecordDecl();
MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
if (hasOnlyOneField(MPT->isMemberFunctionPointer(), Inheritance))
return Builder.CreateICmp(Eq, L, R);
// Compare the first field.
llvm::Value *L0 = Builder.CreateExtractValue(L, 0, "lhs.0");
llvm::Value *R0 = Builder.CreateExtractValue(R, 0, "rhs.0");
llvm::Value *Cmp0 = Builder.CreateICmp(Eq, L0, R0, "memptr.cmp.first");
// Compare everything other than the first field.
llvm::Value *Res = 0;
llvm::StructType *LType = cast<llvm::StructType>(L->getType());
for (unsigned I = 1, E = LType->getNumElements(); I != E; ++I) {
llvm::Value *LF = Builder.CreateExtractValue(L, I);
llvm::Value *RF = Builder.CreateExtractValue(R, I);
llvm::Value *Cmp = Builder.CreateICmp(Eq, LF, RF, "memptr.cmp.rest");
if (Res)
Res = Builder.CreateBinOp(And, Res, Cmp);
else
Res = Cmp;
}
// Check if the first field is 0 if this is a function pointer.
if (MPT->isMemberFunctionPointer()) {
// (l1 == r1 && ...) || l0 == 0
llvm::Value *Zero = llvm::Constant::getNullValue(L0->getType());
llvm::Value *IsZero = Builder.CreateICmp(Eq, L0, Zero, "memptr.cmp.iszero");
Res = Builder.CreateBinOp(Or, Res, IsZero);
}
// Combine the comparison of the first field, which must always be true for
// this comparison to succeeed.
return Builder.CreateBinOp(And, Res, Cmp0, "memptr.cmp");
}
llvm::Value *
MicrosoftCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
llvm::Value *MemPtr,
const MemberPointerType *MPT) {
CGBuilderTy &Builder = CGF.Builder;
llvm::SmallVector<llvm::Constant *, 4> fields;
// We only need one field for member functions.
if (MPT->isMemberFunctionPointer())
fields.push_back(llvm::Constant::getNullValue(CGM.VoidPtrTy));
else
GetNullMemberPointerFields(MPT, fields);
assert(!fields.empty());
llvm::Value *FirstField = MemPtr;
if (MemPtr->getType()->isStructTy())
FirstField = Builder.CreateExtractValue(MemPtr, 0);
llvm::Value *Res = Builder.CreateICmpNE(FirstField, fields[0], "memptr.cmp0");
// For function member pointers, we only need to test the function pointer
// field. The other fields if any can be garbage.
if (MPT->isMemberFunctionPointer())
return Res;
// Otherwise, emit a series of compares and combine the results.
for (int I = 1, E = fields.size(); I < E; ++I) {
llvm::Value *Field = Builder.CreateExtractValue(MemPtr, I);
llvm::Value *Next = Builder.CreateICmpNE(Field, fields[I], "memptr.cmp");
Res = Builder.CreateAnd(Res, Next, "memptr.tobool");
}
return Res;
}
bool MicrosoftCXXABI::MemberPointerConstantIsNull(const MemberPointerType *MPT,
llvm::Constant *Val) {
// Function pointers are null if the pointer in the first field is null.
if (MPT->isMemberFunctionPointer()) {
llvm::Constant *FirstField = Val->getType()->isStructTy() ?
Val->getAggregateElement(0U) : Val;
return FirstField->isNullValue();
}
// If it's not a function pointer and it's zero initializable, we can easily
// check zero.
if (isZeroInitializable(MPT) && Val->isNullValue())
return true;
// Otherwise, break down all the fields for comparison. Hopefully these
// little Constants are reused, while a big null struct might not be.
llvm::SmallVector<llvm::Constant *, 4> Fields;
GetNullMemberPointerFields(MPT, Fields);
if (Fields.size() == 1) {
assert(Val->getType()->isIntegerTy());
return Val == Fields[0];
}
unsigned I, E;
for (I = 0, E = Fields.size(); I != E; ++I) {
if (Val->getAggregateElement(I) != Fields[I])
break;
}
return I == E;
}
llvm::Value *
MicrosoftCXXABI::GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,
llvm::Value *This,
llvm::Value *VBTableOffset,
llvm::Value *VBPtrOffset,
llvm::Value **VBPtrOut) {
CGBuilderTy &Builder = CGF.Builder;
// Load the vbtable pointer from the vbptr in the instance.
This = Builder.CreateBitCast(This, CGM.Int8PtrTy);
llvm::Value *VBPtr =
Builder.CreateInBoundsGEP(This, VBPtrOffset, "vbptr");
if (VBPtrOut) *VBPtrOut = VBPtr;
VBPtr = Builder.CreateBitCast(VBPtr, CGM.Int8PtrTy->getPointerTo(0));
llvm::Value *VBTable = Builder.CreateLoad(VBPtr, "vbtable");
// Load an i32 offset from the vb-table.
llvm::Value *VBaseOffs = Builder.CreateInBoundsGEP(VBTable, VBTableOffset);
VBaseOffs = Builder.CreateBitCast(VBaseOffs, CGM.Int32Ty->getPointerTo(0));
return Builder.CreateLoad(VBaseOffs, "vbase_offs");
}
// Returns an adjusted base cast to i8*, since we do more address arithmetic on
// it.
llvm::Value *
MicrosoftCXXABI::AdjustVirtualBase(CodeGenFunction &CGF,
const CXXRecordDecl *RD, llvm::Value *Base,
llvm::Value *VBTableOffset,
llvm::Value *VBPtrOffset) {
CGBuilderTy &Builder = CGF.Builder;
Base = Builder.CreateBitCast(Base, CGM.Int8PtrTy);
llvm::BasicBlock *OriginalBB = 0;
llvm::BasicBlock *SkipAdjustBB = 0;
llvm::BasicBlock *VBaseAdjustBB = 0;
// In the unspecified inheritance model, there might not be a vbtable at all,
// in which case we need to skip the virtual base lookup. If there is a
// vbtable, the first entry is a no-op entry that gives back the original
// base, so look for a virtual base adjustment offset of zero.
if (VBPtrOffset) {
OriginalBB = Builder.GetInsertBlock();
VBaseAdjustBB = CGF.createBasicBlock("memptr.vadjust");
SkipAdjustBB = CGF.createBasicBlock("memptr.skip_vadjust");
llvm::Value *IsVirtual =
Builder.CreateICmpNE(VBTableOffset, getZeroInt(),
"memptr.is_vbase");
Builder.CreateCondBr(IsVirtual, VBaseAdjustBB, SkipAdjustBB);
CGF.EmitBlock(VBaseAdjustBB);
}
// If we weren't given a dynamic vbptr offset, RD should be complete and we'll
// know the vbptr offset.
if (!VBPtrOffset) {
CharUnits offs = CharUnits::Zero();
if (RD->getNumVBases()) {
offs = GetVBPtrOffsetFromBases(RD);
}
VBPtrOffset = llvm::ConstantInt::get(CGM.IntTy, offs.getQuantity());
}
llvm::Value *VBPtr = 0;
llvm::Value *VBaseOffs =
GetVBaseOffsetFromVBPtr(CGF, Base, VBTableOffset, VBPtrOffset, &VBPtr);
llvm::Value *AdjustedBase = Builder.CreateInBoundsGEP(VBPtr, VBaseOffs);
// Merge control flow with the case where we didn't have to adjust.
if (VBaseAdjustBB) {
Builder.CreateBr(SkipAdjustBB);
CGF.EmitBlock(SkipAdjustBB);
llvm::PHINode *Phi = Builder.CreatePHI(CGM.Int8PtrTy, 2, "memptr.base");
Phi->addIncoming(Base, OriginalBB);
Phi->addIncoming(AdjustedBase, VBaseAdjustBB);
return Phi;
}
return AdjustedBase;
}
llvm::Value *
MicrosoftCXXABI::EmitMemberDataPointerAddress(CodeGenFunction &CGF,
llvm::Value *Base,
llvm::Value *MemPtr,
const MemberPointerType *MPT) {
assert(MPT->isMemberDataPointer());
unsigned AS = Base->getType()->getPointerAddressSpace();
llvm::Type *PType =
CGF.ConvertTypeForMem(MPT->getPointeeType())->getPointerTo(AS);
CGBuilderTy &Builder = CGF.Builder;
const CXXRecordDecl *RD = MPT->getClass()->getAsCXXRecordDecl();
MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
// Extract the fields we need, regardless of model. We'll apply them if we
// have them.
llvm::Value *FieldOffset = MemPtr;
llvm::Value *VirtualBaseAdjustmentOffset = 0;
llvm::Value *VBPtrOffset = 0;
if (MemPtr->getType()->isStructTy()) {
// We need to extract values.
unsigned I = 0;
FieldOffset = Builder.CreateExtractValue(MemPtr, I++);
if (hasVBPtrOffsetField(Inheritance))
VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++);
if (hasVirtualBaseAdjustmentField(Inheritance))
VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++);
}
if (VirtualBaseAdjustmentOffset) {
Base = AdjustVirtualBase(CGF, RD, Base, VirtualBaseAdjustmentOffset,
VBPtrOffset);
}
llvm::Value *Addr =
Builder.CreateInBoundsGEP(Base, FieldOffset, "memptr.offset");
// Cast the address to the appropriate pointer type, adopting the address
// space of the base pointer.
return Builder.CreateBitCast(Addr, PType);
}
static MSInheritanceModel
getInheritanceFromMemptr(const MemberPointerType *MPT) {
return MPT->getClass()->getAsCXXRecordDecl()->getMSInheritanceModel();
}
llvm::Value *
MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
const CastExpr *E,
llvm::Value *Src) {
assert(E->getCastKind() == CK_DerivedToBaseMemberPointer ||
E->getCastKind() == CK_BaseToDerivedMemberPointer ||
E->getCastKind() == CK_ReinterpretMemberPointer);
// Use constant emission if we can.
if (isa<llvm::Constant>(Src))
return EmitMemberPointerConversion(E, cast<llvm::Constant>(Src));
// We may be adding or dropping fields from the member pointer, so we need
// both types and the inheritance models of both records.
const MemberPointerType *SrcTy =
E->getSubExpr()->getType()->castAs<MemberPointerType>();
const MemberPointerType *DstTy = E->getType()->castAs<MemberPointerType>();
MSInheritanceModel SrcInheritance = getInheritanceFromMemptr(SrcTy);
MSInheritanceModel DstInheritance = getInheritanceFromMemptr(DstTy);
bool IsFunc = SrcTy->isMemberFunctionPointer();
// If the classes use the same null representation, reinterpret_cast is a nop.
bool IsReinterpret = E->getCastKind() == CK_ReinterpretMemberPointer;
if (IsReinterpret && (IsFunc ||
nullFieldOffsetIsZero(SrcInheritance) ==
nullFieldOffsetIsZero(DstInheritance)))
return Src;
CGBuilderTy &Builder = CGF.Builder;
// Branch past the conversion if Src is null.
llvm::Value *IsNotNull = EmitMemberPointerIsNotNull(CGF, Src, SrcTy);
llvm::Constant *DstNull = EmitNullMemberPointer(DstTy);
// C++ 5.2.10p9: The null member pointer value is converted to the null member
// pointer value of the destination type.
if (IsReinterpret) {
// For reinterpret casts, sema ensures that src and dst are both functions
// or data and have the same size, which means the LLVM types should match.
assert(Src->getType() == DstNull->getType());
return Builder.CreateSelect(IsNotNull, Src, DstNull);
}
llvm::BasicBlock *OriginalBB = Builder.GetInsertBlock();
llvm::BasicBlock *ConvertBB = CGF.createBasicBlock("memptr.convert");
llvm::BasicBlock *ContinueBB = CGF.createBasicBlock("memptr.converted");
Builder.CreateCondBr(IsNotNull, ConvertBB, ContinueBB);
CGF.EmitBlock(ConvertBB);
// Decompose src.
llvm::Value *FirstField = Src;
llvm::Value *NonVirtualBaseAdjustment = 0;
llvm::Value *VirtualBaseAdjustmentOffset = 0;
llvm::Value *VBPtrOffset = 0;
if (!hasOnlyOneField(IsFunc, SrcInheritance)) {
// We need to extract values.
unsigned I = 0;
FirstField = Builder.CreateExtractValue(Src, I++);
if (hasNonVirtualBaseAdjustmentField(IsFunc, SrcInheritance))
NonVirtualBaseAdjustment = Builder.CreateExtractValue(Src, I++);
if (hasVBPtrOffsetField(SrcInheritance))
VBPtrOffset = Builder.CreateExtractValue(Src, I++);
if (hasVirtualBaseAdjustmentField(SrcInheritance))
VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(Src, I++);
}
// For data pointers, we adjust the field offset directly. For functions, we
// have a separate field.
llvm::Constant *Adj = getMemberPointerAdjustment(E);
if (Adj) {
Adj = llvm::ConstantExpr::getTruncOrBitCast(Adj, CGM.IntTy);
llvm::Value *&NVAdjustField = IsFunc ? NonVirtualBaseAdjustment : FirstField;
bool isDerivedToBase = (E->getCastKind() == CK_DerivedToBaseMemberPointer);
if (!NVAdjustField) // If this field didn't exist in src, it's zero.
NVAdjustField = getZeroInt();
if (isDerivedToBase)
NVAdjustField = Builder.CreateNSWSub(NVAdjustField, Adj, "adj");
else
NVAdjustField = Builder.CreateNSWAdd(NVAdjustField, Adj, "adj");
}
// FIXME PR15713: Support conversions through virtually derived classes.
// Recompose dst from the null struct and the adjusted fields from src.
llvm::Value *Dst;
if (hasOnlyOneField(IsFunc, DstInheritance)) {
Dst = FirstField;
} else {
Dst = llvm::UndefValue::get(DstNull->getType());
unsigned Idx = 0;
Dst = Builder.CreateInsertValue(Dst, FirstField, Idx++);
if (hasNonVirtualBaseAdjustmentField(IsFunc, DstInheritance))
Dst = Builder.CreateInsertValue(
Dst, getValueOrZeroInt(NonVirtualBaseAdjustment), Idx++);
if (hasVBPtrOffsetField(DstInheritance))
Dst = Builder.CreateInsertValue(
Dst, getValueOrZeroInt(VBPtrOffset), Idx++);
if (hasVirtualBaseAdjustmentField(DstInheritance))
Dst = Builder.CreateInsertValue(
Dst, getValueOrZeroInt(VirtualBaseAdjustmentOffset), Idx++);
}
Builder.CreateBr(ContinueBB);
// In the continuation, choose between DstNull and Dst.
CGF.EmitBlock(ContinueBB);
llvm::PHINode *Phi = Builder.CreatePHI(DstNull->getType(), 2, "memptr.converted");
Phi->addIncoming(DstNull, OriginalBB);
Phi->addIncoming(Dst, ConvertBB);
return Phi;
}
llvm::Constant *
MicrosoftCXXABI::EmitMemberPointerConversion(const CastExpr *E,
llvm::Constant *Src) {
const MemberPointerType *SrcTy =
E->getSubExpr()->getType()->castAs<MemberPointerType>();
const MemberPointerType *DstTy = E->getType()->castAs<MemberPointerType>();
// If src is null, emit a new null for dst. We can't return src because dst
// might have a new representation.
if (MemberPointerConstantIsNull(SrcTy, Src))
return EmitNullMemberPointer(DstTy);
// We don't need to do anything for reinterpret_casts of non-null member
// pointers. We should only get here when the two type representations have
// the same size.
if (E->getCastKind() == CK_ReinterpretMemberPointer)
return Src;
MSInheritanceModel SrcInheritance = getInheritanceFromMemptr(SrcTy);
MSInheritanceModel DstInheritance = getInheritanceFromMemptr(DstTy);
// Decompose src.
llvm::Constant *FirstField = Src;
llvm::Constant *NonVirtualBaseAdjustment = 0;
llvm::Constant *VirtualBaseAdjustmentOffset = 0;
llvm::Constant *VBPtrOffset = 0;
bool IsFunc = SrcTy->isMemberFunctionPointer();
if (!hasOnlyOneField(IsFunc, SrcInheritance)) {
// We need to extract values.
unsigned I = 0;
FirstField = Src->getAggregateElement(I++);
if (hasNonVirtualBaseAdjustmentField(IsFunc, SrcInheritance))
NonVirtualBaseAdjustment = Src->getAggregateElement(I++);
if (hasVBPtrOffsetField(SrcInheritance))
VBPtrOffset = Src->getAggregateElement(I++);
if (hasVirtualBaseAdjustmentField(SrcInheritance))
VirtualBaseAdjustmentOffset = Src->getAggregateElement(I++);
}
// For data pointers, we adjust the field offset directly. For functions, we
// have a separate field.
llvm::Constant *Adj = getMemberPointerAdjustment(E);
if (Adj) {
Adj = llvm::ConstantExpr::getTruncOrBitCast(Adj, CGM.IntTy);
llvm::Constant *&NVAdjustField =
IsFunc ? NonVirtualBaseAdjustment : FirstField;
bool IsDerivedToBase = (E->getCastKind() == CK_DerivedToBaseMemberPointer);
if (!NVAdjustField) // If this field didn't exist in src, it's zero.
NVAdjustField = getZeroInt();
if (IsDerivedToBase)
NVAdjustField = llvm::ConstantExpr::getNSWSub(NVAdjustField, Adj);
else
NVAdjustField = llvm::ConstantExpr::getNSWAdd(NVAdjustField, Adj);
}
// FIXME PR15713: Support conversions through virtually derived classes.
// Recompose dst from the null struct and the adjusted fields from src.
if (hasOnlyOneField(IsFunc, DstInheritance))
return FirstField;
llvm::SmallVector<llvm::Constant *, 4> Fields;
Fields.push_back(FirstField);
if (hasNonVirtualBaseAdjustmentField(IsFunc, DstInheritance))
Fields.push_back(getConstantOrZeroInt(NonVirtualBaseAdjustment));
if (hasVBPtrOffsetField(DstInheritance))
Fields.push_back(getConstantOrZeroInt(VBPtrOffset));
if (hasVirtualBaseAdjustmentField(DstInheritance))
Fields.push_back(getConstantOrZeroInt(VirtualBaseAdjustmentOffset));
return llvm::ConstantStruct::getAnon(Fields);
}
llvm::Value *
MicrosoftCXXABI::EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF,
llvm::Value *&This,
llvm::Value *MemPtr,
const MemberPointerType *MPT) {
assert(MPT->isMemberFunctionPointer());
const FunctionProtoType *FPT =
MPT->getPointeeType()->castAs<FunctionProtoType>();
const CXXRecordDecl *RD = MPT->getClass()->getAsCXXRecordDecl();
llvm::FunctionType *FTy =
CGM.getTypes().GetFunctionType(
CGM.getTypes().arrangeCXXMethodType(RD, FPT));
CGBuilderTy &Builder = CGF.Builder;
MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
// Extract the fields we need, regardless of model. We'll apply them if we
// have them.
llvm::Value *FunctionPointer = MemPtr;
llvm::Value *NonVirtualBaseAdjustment = NULL;
llvm::Value *VirtualBaseAdjustmentOffset = NULL;
llvm::Value *VBPtrOffset = NULL;
if (MemPtr->getType()->isStructTy()) {
// We need to extract values.
unsigned I = 0;
FunctionPointer = Builder.CreateExtractValue(MemPtr, I++);
if (hasNonVirtualBaseAdjustmentField(MPT, Inheritance))
NonVirtualBaseAdjustment = Builder.CreateExtractValue(MemPtr, I++);
if (hasVBPtrOffsetField(Inheritance))
VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++);
if (hasVirtualBaseAdjustmentField(Inheritance))
VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++);
}
if (VirtualBaseAdjustmentOffset) {
This = AdjustVirtualBase(CGF, RD, This, VirtualBaseAdjustmentOffset,
VBPtrOffset);
}
if (NonVirtualBaseAdjustment) {
// Apply the adjustment and cast back to the original struct type.
llvm::Value *Ptr = Builder.CreateBitCast(This, Builder.getInt8PtrTy());
Ptr = Builder.CreateInBoundsGEP(Ptr, NonVirtualBaseAdjustment);
This = Builder.CreateBitCast(Ptr, This->getType(), "this.adjusted");
}
return Builder.CreateBitCast(FunctionPointer, FTy->getPointerTo());
}
CGCXXABI *clang::CodeGen::CreateMicrosoftCXXABI(CodeGenModule &CGM) {
return new MicrosoftCXXABI(CGM);
}
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