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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 "CGVTables.h"
#include "CodeGenModule.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/VTableBuilder.h"
#include "llvm/ADT/StringSet.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) {}
bool HasThisReturn(GlobalDecl GD) const override;
bool classifyReturnType(CGFunctionInfo &FI) const override;
RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const override;
bool isSRetParameterAfterThis() const override { return true; }
StringRef GetPureVirtualCallName() override { return "_purecall"; }
// No known support for deleted functions in MSVC yet, so this choice is
// arbitrary.
StringRef GetDeletedVirtualCallName() override { return "_purecall"; }
bool isInlineInitializedStaticDataMemberLinkOnce() override { return true; }
llvm::Value *adjustToCompleteObject(CodeGenFunction &CGF,
llvm::Value *ptr,
QualType type) override;
llvm::Value *
GetVirtualBaseClassOffset(CodeGenFunction &CGF, llvm::Value *This,
const CXXRecordDecl *ClassDecl,
const CXXRecordDecl *BaseClassDecl) override;
void BuildConstructorSignature(const CXXConstructorDecl *Ctor,
CXXCtorType Type, CanQualType &ResTy,
SmallVectorImpl<CanQualType> &ArgTys) override;
llvm::BasicBlock *
EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
const CXXRecordDecl *RD) override;
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.
void BuildDestructorSignature(const CXXDestructorDecl *Dtor,
CXXDtorType Type,
CanQualType &ResTy,
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();
}
llvm::Value *
adjustThisArgumentForVirtualFunctionCall(CodeGenFunction &CGF, GlobalDecl GD,
llvm::Value *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;
unsigned 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, llvm::Value *This) override;
void emitVTableDefinitions(CodeGenVTables &CGVT,
const CXXRecordDecl *RD) override;
llvm::Value *getVTableAddressPointInStructor(
CodeGenFunction &CGF, const CXXRecordDecl *VTableClass,
BaseSubobject Base, const CXXRecordDecl *NearestVBase,
bool &NeedsVirtualOffset) override;
llvm::Constant *
getVTableAddressPointForConstExpr(BaseSubobject Base,
const CXXRecordDecl *VTableClass) override;
llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD,
CharUnits VPtrOffset) override;
llvm::Value *getVirtualFunctionPointer(CodeGenFunction &CGF, GlobalDecl GD,
llvm::Value *This,
llvm::Type *Ty) override;
void EmitVirtualDestructorCall(CodeGenFunction &CGF,
const CXXDestructorDecl *Dtor,
CXXDtorType DtorType, SourceLocation CallLoc,
llvm::Value *This) 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)),
CGM.getContext().IntTy);
}
void emitVirtualInheritanceTables(const CXXRecordDecl *RD) override;
llvm::GlobalVariable *
getAddrOfVBTable(const VPtrInfo &VBT, const CXXRecordDecl *RD,
llvm::GlobalVariable::LinkageTypes Linkage);
void emitVBTableDefinition(const VPtrInfo &VBT, const CXXRecordDecl *RD,
llvm::GlobalVariable *GV) const;
void setThunkLinkage(llvm::Function *Thunk, bool ForVTable) override {
Thunk->setLinkage(llvm::GlobalValue::WeakAnyLinkage);
// Never dllimport/dllexport thunks.
Thunk->setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass);
}
llvm::Value *performThisAdjustment(CodeGenFunction &CGF, llvm::Value *This,
const ThisAdjustment &TA) override;
llvm::Value *performReturnAdjustment(CodeGenFunction &CGF, llvm::Value *Ret,
const ReturnAdjustment &RA) override;
void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
llvm::GlobalVariable *DeclPtr,
bool PerformInit) 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;
llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF,
llvm::Value *NewPtr,
llvm::Value *NumElements,
const CXXNewExpr *expr,
QualType ElementType) override;
llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF,
llvm::Value *allocPtr,
CharUnits cookieSize) override;
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);
}
llvm::Constant *getConstantOrZeroInt(llvm::Constant *C) {
return C ? C : getZeroInt();
}
llvm::Value *getValueOrZeroInt(llvm::Value *C) {
return C ? C : getZeroInt();
}
CharUnits getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD);
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,
llvm::Value *Base,
llvm::Value *VBPtrOffset,
llvm::Value *VBTableOffset,
llvm::Value **VBPtr = nullptr);
llvm::Value *GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,
llvm::Value *Base,
int32_t VBPtrOffset,
int32_t VBTableOffset,
llvm::Value **VBPtr = nullptr) {
llvm::Value *VBPOffset = llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset),
*VBTOffset = llvm::ConstantInt::get(CGM.IntTy, VBTableOffset);
return GetVBaseOffsetFromVBPtr(CGF, Base, VBPOffset, VBTOffset, VBPtr);
}
/// \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, 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 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;
llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT) override;
llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,
CharUnits offset) override;
llvm::Constant *EmitMemberPointer(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,
llvm::Value *Base, llvm::Value *MemPtr,
const MemberPointerType *MPT) override;
llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,
const CastExpr *E,
llvm::Value *Src) override;
llvm::Constant *EmitMemberPointerConversion(const CastExpr *E,
llvm::Constant *Src) override;
llvm::Value *
EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, const Expr *E,
llvm::Value *&This, llvm::Value *MemPtr,
const MemberPointerType *MPT) override;
private:
typedef std::pair<const CXXRecordDecl *, CharUnits> VFTableIdTy;
typedef llvm::DenseMap<VFTableIdTy, llvm::GlobalVariable *> VFTablesMapTy;
/// \brief All the vftables that have been referenced.
VFTablesMapTy VFTablesMap;
/// \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;
};
}
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::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;
// Win64 passes objects larger than 8 bytes indirectly.
if (getContext().getTypeSize(RD->getTypeForDecl()) > 64)
return RAA_Indirect;
// We have a trivial copy constructor or no copy constructors, but we have
// to make sure it isn't deleted.
bool CopyDeleted = false;
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;
CopyDeleted = true;
}
}
// The trivial copy constructor was deleted. Return indirectly.
if (CopyDeleted)
return RAA_Indirect;
// There were no copy ctors. Return in RAX.
return RAA_Default;
}
llvm_unreachable("invalid enum");
}
llvm::Value *MicrosoftCXXABI::adjustToCompleteObject(CodeGenFunction &CGF,
llvm::Value *ptr,
QualType type) {
// FIXME: implement
return ptr;
}
llvm::Value *
MicrosoftCXXABI::GetVirtualBaseClassOffset(CodeGenFunction &CGF,
llvm::Value *This,
const CXXRecordDecl *ClassDecl,
const CXXRecordDecl *BaseClassDecl) {
int64_t VBPtrChars =
getContext().getASTRecordLayout(ClassDecl).getVBPtrOffset().getQuantity();
llvm::Value *VBPtrOffset = llvm::ConstantInt::get(CGM.PtrDiffTy, VBPtrChars);
CharUnits IntSize = getContext().getTypeSizeInChars(getContext().IntTy);
CharUnits VBTableChars =
IntSize *
CGM.getMicrosoftVTableContext().getVBTableIndex(ClassDecl, BaseClassDecl);
llvm::Value *VBTableOffset =
llvm::ConstantInt::get(CGM.IntTy, VBTableChars.getQuantity());
llvm::Value *VBPtrToNewBase =
GetVBaseOffsetFromVBPtr(CGF, This, VBPtrOffset, VBTableOffset);
VBPtrToNewBase =
CGF.Builder.CreateSExtOrBitCast(VBPtrToNewBase, CGM.PtrDiffTy);
return CGF.Builder.CreateNSWAdd(VBPtrOffset, VBPtrToNewBase);
}
bool MicrosoftCXXABI::HasThisReturn(GlobalDecl GD) const {
return isa<CXXConstructorDecl>(GD.getDecl());
}
bool MicrosoftCXXABI::classifyReturnType(CGFunctionInfo &FI) const {
const CXXRecordDecl *RD = FI.getReturnType()->getAsCXXRecordDecl();
if (!RD)
return false;
if (FI.isInstanceMethod()) {
// If it's an instance method, aggregates are always returned indirectly via
// the second parameter.
FI.getReturnInfo() = ABIArgInfo::getIndirect(0, /*ByVal=*/false);
FI.getReturnInfo().setSRetAfterThis(FI.isInstanceMethod());
return true;
} else if (!RD->isPOD()) {
// If it's a free function, non-POD types are returned indirectly.
FI.getReturnInfo() = ABIArgInfo::getIndirect(0, /*ByVal=*/false);
return true;
}
// Otherwise, use the C ABI rules.
return false;
}
void MicrosoftCXXABI::BuildConstructorSignature(
const CXXConstructorDecl *Ctor, CXXCtorType Type, CanQualType &ResTy,
SmallVectorImpl<CanQualType> &ArgTys) {
// All parameters are already in place except is_most_derived, which goes
// after 'this' if it's variadic and last if it's not.
const CXXRecordDecl *Class = Ctor->getParent();
const FunctionProtoType *FPT = Ctor->getType()->castAs<FunctionProtoType>();
if (Class->getNumVBases()) {
if (FPT->isVariadic())
ArgTys.insert(ArgTys.begin() + 1, CGM.getContext().IntTy);
else
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::initializeHiddenVirtualInheritanceMembers(
CodeGenFunction &CGF, const CXXRecordDecl *RD) {
// In most cases, an override for a vbase virtual method can adjust
// the "this" parameter by applying a constant offset.
// However, this is not enough while a constructor or a destructor of some
// class X is being executed if all the following conditions are met:
// - X has virtual bases, (1)
// - X overrides a virtual method M of a vbase Y, (2)
// - X itself is a vbase of the most derived class.
//
// If (1) and (2) are true, the vtorDisp for vbase Y is a hidden member of X
// which holds the extra amount of "this" adjustment we must do when we use
// the X vftables (i.e. during X ctor or dtor).
// Outside the ctors and dtors, the values of vtorDisps are zero.
const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
typedef ASTRecordLayout::VBaseOffsetsMapTy VBOffsets;
const VBOffsets &VBaseMap = Layout.getVBaseOffsetsMap();
CGBuilderTy &Builder = CGF.Builder;
unsigned AS =
cast<llvm::PointerType>(getThisValue(CGF)->getType())->getAddressSpace();
llvm::Value *Int8This = nullptr; // Initialize lazily.
for (VBOffsets::const_iterator I = VBaseMap.begin(), E = VBaseMap.end();
I != E; ++I) {
if (!I->second.hasVtorDisp())
continue;
llvm::Value *VBaseOffset =
GetVirtualBaseClassOffset(CGF, getThisValue(CGF), RD, I->first);
// FIXME: it doesn't look right that we SExt in GetVirtualBaseClassOffset()
// just to Trunc back immediately.
VBaseOffset = Builder.CreateTruncOrBitCast(VBaseOffset, CGF.Int32Ty);
uint64_t ConstantVBaseOffset =
Layout.getVBaseClassOffset(I->first).getQuantity();
// vtorDisp_for_vbase = vbptr[vbase_idx] - offsetof(RD, vbase).
llvm::Value *VtorDispValue = Builder.CreateSub(
VBaseOffset, llvm::ConstantInt::get(CGM.Int32Ty, ConstantVBaseOffset),
"vtordisp.value");
if (!Int8This)
Int8This = Builder.CreateBitCast(getThisValue(CGF),
CGF.Int8Ty->getPointerTo(AS));
llvm::Value *VtorDispPtr = Builder.CreateInBoundsGEP(Int8This, VBaseOffset);
// vtorDisp is always the 32-bits before the vbase in the class layout.
VtorDispPtr = Builder.CreateConstGEP1_32(VtorDispPtr, -4);
VtorDispPtr = Builder.CreateBitCast(
VtorDispPtr, CGF.Int32Ty->getPointerTo(AS), "vtordisp.ptr");
Builder.CreateStore(VtorDispValue, VtorDispPtr);
}
}
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 ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);
const VBTableGlobals &VBGlobals = enumerateVBTables(RD);
for (unsigned I = 0, E = VBGlobals.VBTables->size(); I != E; ++I) {
const VPtrInfo *VBT = (*VBGlobals.VBTables)[I];
llvm::GlobalVariable *GV = VBGlobals.Globals[I];
const ASTRecordLayout &SubobjectLayout =
CGM.getContext().getASTRecordLayout(VBT->BaseWithVPtr);
CharUnits Offs = VBT->NonVirtualOffset;
Offs += SubobjectLayout.getVBPtrOffset();
if (VBT->getVBaseWithVPtr())
Offs += Layout.getVBaseClassOffset(VBT->getVBaseWithVPtr());
llvm::Value *VBPtr =
CGF.Builder.CreateConstInBoundsGEP1_64(ThisInt8Ptr, Offs.getQuantity());
VBPtr = CGF.Builder.CreateBitCast(VBPtr, GV->getType()->getPointerTo(0),
"vbptr." + VBT->ReusingBase->getName());
CGF.Builder.CreateStore(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 int parameter.
ArgTys.push_back(CGM.getContext().IntTy);
}
}
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));
}
CharUnits
MicrosoftCXXABI::getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) {
GD = GD.getCanonicalDecl();
const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
GlobalDecl LookupGD = GD;
if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
// Complete destructors take a pointer to the complete object as a
// parameter, thus don't need this adjustment.
if (GD.getDtorType() == Dtor_Complete)
return CharUnits();
// There's no Dtor_Base in vftable but it shares the this adjustment with
// the deleting one, so look it up instead.
LookupGD = GlobalDecl(DD, Dtor_Deleting);
}
MicrosoftVTableContext::MethodVFTableLocation ML =
CGM.getMicrosoftVTableContext().getMethodVFTableLocation(LookupGD);
CharUnits Adjustment = ML.VFPtrOffset;
// Normal virtual instance methods need to adjust from the vfptr that first
// defined the virtual method to the virtual base subobject, but destructors
// do not. The vector deleting destructor thunk applies this adjustment for
// us if necessary.
if (isa<CXXDestructorDecl>(MD))
Adjustment = CharUnits::Zero();
if (ML.VBase) {
const ASTRecordLayout &DerivedLayout =
CGM.getContext().getASTRecordLayout(MD->getParent());
Adjustment += DerivedLayout.getVBaseClassOffset(ML.VBase);
}
return Adjustment;
}
llvm::Value *MicrosoftCXXABI::adjustThisArgumentForVirtualFunctionCall(
CodeGenFunction &CGF, GlobalDecl GD, llvm::Value *This, bool VirtualCall) {
if (!VirtualCall) {
// If the call of a virtual function is not virtual, we just have to
// compensate for the adjustment the virtual function does in its prologue.
CharUnits Adjustment = getVirtualFunctionPrologueThisAdjustment(GD);
if (Adjustment.isZero())
return This;
unsigned AS = cast<llvm::PointerType>(This->getType())->getAddressSpace();
llvm::Type *charPtrTy = CGF.Int8Ty->getPointerTo(AS);
This = CGF.Builder.CreateBitCast(This, charPtrTy);
assert(Adjustment.isPositive());
return CGF.Builder.CreateConstGEP1_32(This, Adjustment.getQuantity());
}
GD = GD.getCanonicalDecl();
const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
GlobalDecl LookupGD = GD;
if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
// Complete dtors take a pointer to the complete object,
// thus don't need adjustment.
if (GD.getDtorType() == Dtor_Complete)
return This;
// There's only Dtor_Deleting in vftable but it shares the this adjustment
// with the base one, so look up the deleting one instead.
LookupGD = GlobalDecl(DD, Dtor_Deleting);
}
MicrosoftVTableContext::MethodVFTableLocation ML =
CGM.getMicrosoftVTableContext().getMethodVFTableLocation(LookupGD);
unsigned AS = cast<llvm::PointerType>(This->getType())->getAddressSpace();
llvm::Type *charPtrTy = CGF.Int8Ty->getPointerTo(AS);
CharUnits StaticOffset = ML.VFPtrOffset;
// Base destructors expect 'this' to point to the beginning of the base
// subobject, not the first vfptr that happens to contain the virtual dtor.
// However, we still need to apply the virtual base adjustment.
if (isa<CXXDestructorDecl>(MD) && GD.getDtorType() == Dtor_Base)
StaticOffset = CharUnits::Zero();
if (ML.VBase) {
This = CGF.Builder.CreateBitCast(This, charPtrTy);
llvm::Value *VBaseOffset =
GetVirtualBaseClassOffset(CGF, This, MD->getParent(), ML.VBase);
This = CGF.Builder.CreateInBoundsGEP(This, VBaseOffset);
}
if (!StaticOffset.isZero()) {
assert(StaticOffset.isPositive());
This = CGF.Builder.CreateBitCast(This, charPtrTy);
if (ML.VBase) {
// Non-virtual adjustment might result in a pointer outside the allocated
// object, e.g. if the final overrider class is laid out after the virtual
// base that declares a method in the most derived class.
// FIXME: Update the code that emits this adjustment in thunks prologues.
This = CGF.Builder.CreateConstGEP1_32(This, StaticOffset.getQuantity());
} else {
This = CGF.Builder.CreateConstInBoundsGEP1_32(This,
StaticOffset.getQuantity());
}
}
return This;
}
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::addImplicitStructorParams(CodeGenFunction &CGF,
QualType &ResTy,
FunctionArgList &Params) {
ASTContext &Context = getContext();
const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
assert(isa<CXXConstructorDecl>(MD) || isa<CXXDestructorDecl>(MD));
if (isa<CXXConstructorDecl>(MD) && MD->getParent()->getNumVBases()) {
ImplicitParamDecl *IsMostDerived
= ImplicitParamDecl::Create(Context, nullptr,
CGF.CurGD.getDecl()->getLocation(),
&Context.Idents.get("is_most_derived"),
Context.IntTy);
// The 'most_derived' parameter goes second if the ctor is variadic and last
// if it's not. Dtors can't be variadic.
const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>();
if (FPT->isVariadic())
Params.insert(Params.begin() + 1, IsMostDerived);
else
Params.push_back(IsMostDerived);
getStructorImplicitParamDecl(CGF) = IsMostDerived;
} else if (IsDeletingDtor(CGF.CurGD)) {
ImplicitParamDecl *ShouldDelete
= ImplicitParamDecl::Create(Context, nullptr,
CGF.CurGD.getDecl()->getLocation(),
&Context.Idents.get("should_call_delete"),
Context.IntTy);
Params.push_back(ShouldDelete);
getStructorImplicitParamDecl(CGF) = ShouldDelete;
}
}
llvm::Value *MicrosoftCXXABI::adjustThisParameterInVirtualFunctionPrologue(
CodeGenFunction &CGF, GlobalDecl GD, llvm::Value *This) {
// In this ABI, every virtual function takes a pointer to one of the
// subobjects that first defines it as the 'this' parameter, rather than a
// pointer to the final overrider subobject. Thus, we need to adjust it back
// to the final overrider subobject before use.
// See comments in the MicrosoftVFTableContext implementation for the details.
CharUnits Adjustment = getVirtualFunctionPrologueThisAdjustment(GD);
if (Adjustment.isZero())
return This;
unsigned AS = cast<llvm::PointerType>(This->getType())->getAddressSpace();
llvm::Type *charPtrTy = CGF.Int8Ty->getPointerTo(AS),
*thisTy = This->getType();
This = CGF.Builder.CreateBitCast(This, charPtrTy);
assert(Adjustment.isPositive());
This =
CGF.Builder.CreateConstInBoundsGEP1_32(This, -Adjustment.getQuantity());
return CGF.Builder.CreateBitCast(This, thisTy);
}
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");
}
}
unsigned MicrosoftCXXABI::addImplicitConstructorArgs(
CodeGenFunction &CGF, const CXXConstructorDecl *D, CXXCtorType Type,
bool ForVirtualBase, bool Delegating, CallArgList &Args) {
assert(Type == Ctor_Complete || Type == Ctor_Base);
// Check if we need a 'most_derived' parameter.
if (!D->getParent()->getNumVBases())
return 0;
// Add the 'most_derived' argument second if we are variadic or last if not.
const FunctionProtoType *FPT = D->getType()->castAs<FunctionProtoType>();
llvm::Value *MostDerivedArg =
llvm::ConstantInt::get(CGM.Int32Ty, Type == Ctor_Complete);
RValue RV = RValue::get(MostDerivedArg);
if (MostDerivedArg) {
if (FPT->isVariadic())
Args.insert(Args.begin() + 1,
CallArg(RV, getContext().IntTy, /*needscopy=*/false));
else
Args.add(RV, getContext().IntTy);
}
return 1; // Added one arg.
}
void MicrosoftCXXABI::EmitDestructorCall(CodeGenFunction &CGF,
const CXXDestructorDecl *DD,
CXXDtorType Type, bool ForVirtualBase,
bool Delegating, llvm::Value *This) {
llvm::Value *Callee = CGM.GetAddrOfCXXDestructor(DD, Type);
if (DD->isVirtual()) {
assert(Type != CXXDtorType::Dtor_Deleting &&
"The deleting destructor should only be called via a virtual call");
This = adjustThisArgumentForVirtualFunctionCall(CGF, GlobalDecl(DD, Type),
This, false);
}
// FIXME: Provide a source location here.
CGF.EmitCXXMemberCall(DD, SourceLocation(), Callee, ReturnValueSlot(), This,
/*ImplicitParam=*/nullptr,
/*ImplicitParamTy=*/QualType(), nullptr, nullptr);
}
void MicrosoftCXXABI::emitVTableDefinitions(CodeGenVTables &CGVT,
const CXXRecordDecl *RD) {
MicrosoftVTableContext &VFTContext = CGM.getMicrosoftVTableContext();
VPtrInfoVector VFPtrs = VFTContext.getVFPtrOffsets(RD);
llvm::GlobalVariable::LinkageTypes Linkage = CGM.getVTableLinkage(RD);
for (VPtrInfo *Info : VFPtrs) {
llvm::GlobalVariable *VTable = getAddrOfVTable(RD, Info->FullOffsetInMDC);
if (VTable->hasInitializer())
continue;
if (getContext().getLangOpts().RTTI)
CGM.getMSCompleteObjectLocator(RD, Info);
const VTableLayout &VTLayout =
VFTContext.getVFTableLayout(RD, Info->FullOffsetInMDC);
llvm::Constant *Init = CGVT.CreateVTableInitializer(
RD, VTLayout.vtable_component_begin(),
VTLayout.getNumVTableComponents(), VTLayout.vtable_thunk_begin(),
VTLayout.getNumVTableThunks());
VTable->setInitializer(Init);
VTable->setLinkage(Linkage);
CGM.setGlobalVisibility(VTable, RD);
}
}
llvm::Value *MicrosoftCXXABI::getVTableAddressPointInStructor(
CodeGenFunction &CGF, const CXXRecordDecl *VTableClass, BaseSubobject Base,
const CXXRecordDecl *NearestVBase, bool &NeedsVirtualOffset) {
NeedsVirtualOffset = (NearestVBase != nullptr);
llvm::Value *VTableAddressPoint =
getAddrOfVTable(VTableClass, Base.getBaseOffset());
if (!VTableAddressPoint) {
assert(Base.getBase()->getNumVBases() &&
!CGM.getContext().getASTRecordLayout(Base.getBase()).hasOwnVFPtr());
}
return VTableAddressPoint;
}
static void mangleVFTableName(MicrosoftMangleContext &MangleContext,
const CXXRecordDecl *RD, const VPtrInfo *VFPtr,
SmallString<256> &Name) {
llvm::raw_svector_ostream Out(Name);
MangleContext.mangleCXXVFTable(RD, VFPtr->MangledPath, Out);
}
llvm::Constant *MicrosoftCXXABI::getVTableAddressPointForConstExpr(
BaseSubobject Base, const CXXRecordDecl *VTableClass) {
llvm::Constant *VTable = getAddrOfVTable(VTableClass, Base.getBaseOffset());
assert(VTable && "Couldn't find a vftable for the given base?");
return VTable;
}
llvm::GlobalVariable *MicrosoftCXXABI::getAddrOfVTable(const CXXRecordDecl *RD,
CharUnits VPtrOffset) {
// getAddrOfVTable may return 0 if asked to get an address of a vtable which
// shouldn't be used in the given record type. We want to cache this result in
// VFTablesMap, thus a simple zero check is not sufficient.
VFTableIdTy ID(RD, VPtrOffset);
VFTablesMapTy::iterator I;
bool Inserted;
std::tie(I, Inserted) = VFTablesMap.insert(std::make_pair(ID, nullptr));
if (!Inserted)
return I->second;
llvm::GlobalVariable *&VTable = I->second;
MicrosoftVTableContext &VTContext = CGM.getMicrosoftVTableContext();
const VPtrInfoVector &VFPtrs = VTContext.getVFPtrOffsets(RD);
if (DeferredVFTables.insert(RD)) {
// We haven't processed this record type before.
// Queue up this v-table for possible deferred emission.
CGM.addDeferredVTable(RD);
#ifndef NDEBUG
// Create all the vftables at once in order to make sure each vftable has
// a unique mangled name.
llvm::StringSet<> ObservedMangledNames;
for (size_t J = 0, F = VFPtrs.size(); J != F; ++J) {
SmallString<256> Name;
mangleVFTableName(getMangleContext(), RD, VFPtrs[J], Name);
if (!ObservedMangledNames.insert(Name.str()))
llvm_unreachable("Already saw this mangling before?");
}
#endif
}
for (size_t J = 0, F = VFPtrs.size(); J != F; ++J) {
if (VFPtrs[J]->FullOffsetInMDC != VPtrOffset)
continue;
llvm::ArrayType *ArrayType = llvm::ArrayType::get(
CGM.Int8PtrTy,
VTContext.getVFTableLayout(RD, VFPtrs[J]->FullOffsetInMDC)
.getNumVTableComponents());
SmallString<256> Name;
mangleVFTableName(getMangleContext(), RD, VFPtrs[J], Name);
VTable = CGM.CreateOrReplaceCXXRuntimeVariable(
Name.str(), ArrayType, llvm::GlobalValue::ExternalLinkage);
VTable->setUnnamedAddr(true);
if (RD->hasAttr<DLLImportAttr>())
VTable->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass);
else if (RD->hasAttr<DLLExportAttr>())
VTable->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);
break;
}
return VTable;
}
llvm::Value *MicrosoftCXXABI::getVirtualFunctionPointer(CodeGenFunction &CGF,
GlobalDecl GD,
llvm::Value *This,
llvm::Type *Ty) {
GD = GD.getCanonicalDecl();
CGBuilderTy &Builder = CGF.Builder;
Ty = Ty->getPointerTo()->getPointerTo();
llvm::Value *VPtr =
adjustThisArgumentForVirtualFunctionCall(CGF, GD, This, true);
llvm::Value *VTable = CGF.GetVTablePtr(VPtr, Ty);
MicrosoftVTableContext::MethodVFTableLocation ML =
CGM.getMicrosoftVTableContext().getMethodVFTableLocation(GD);
llvm::Value *VFuncPtr =
Builder.CreateConstInBoundsGEP1_64(VTable, ML.Index, "vfn");
return Builder.CreateLoad(VFuncPtr);
}
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 int parameter.
GlobalDecl GD(Dtor, Dtor_Deleting);
const CGFunctionInfo *FInfo =
&CGM.getTypes().arrangeCXXDestructor(Dtor, Dtor_Deleting);
llvm::Type *Ty = CGF.CGM.getTypes().GetFunctionType(*FInfo);
llvm::Value *Callee = getVirtualFunctionPointer(CGF, GD, This, Ty);
ASTContext &Context = CGF.getContext();
llvm::Value *ImplicitParam =
llvm::ConstantInt::get(llvm::IntegerType::getInt32Ty(CGF.getLLVMContext()),
DtorType == Dtor_Deleting);
This = adjustThisArgumentForVirtualFunctionCall(CGF, GD, This, true);
CGF.EmitCXXMemberCall(Dtor, CallLoc, Callee, ReturnValueSlot(), This,
ImplicitParam, Context.IntTy, nullptr, nullptr);
}
const VBTableGlobals &
MicrosoftCXXABI::enumerateVBTables(const CXXRecordDecl *RD) {
// At this layer, we can key the cache off of a single class, which is much
// easier than caching each vbtable individually.
llvm::DenseMap<const CXXRecordDecl*, VBTableGlobals>::iterator Entry;
bool Added;
std::tie(Entry, Added) =
VBTablesMap.insert(std::make_pair(RD, VBTableGlobals()));
VBTableGlobals &VBGlobals = Entry->second;
if (!Added)
return VBGlobals;
MicrosoftVTableContext &Context = CGM.getMicrosoftVTableContext();
VBGlobals.VBTables = &Context.enumerateVBTables(RD);
// Cache the globals for all vbtables so we don't have to recompute the
// mangled names.
llvm::GlobalVariable::LinkageTypes Linkage = CGM.getVTableLinkage(RD);
for (VPtrInfoVector::const_iterator I = VBGlobals.VBTables->begin(),
E = VBGlobals.VBTables->end();
I != E; ++I) {
VBGlobals.Globals.push_back(getAddrOfVBTable(**I, RD, Linkage));
}
return VBGlobals;
}
llvm::Function *MicrosoftCXXABI::EmitVirtualMemPtrThunk(
const CXXMethodDecl *MD,
const MicrosoftVTableContext::MethodVFTableLocation &ML) {
// Calculate the mangled name.
SmallString<256> ThunkName;
llvm::raw_svector_ostream Out(ThunkName);
getMangleContext().mangleVirtualMemPtrThunk(MD, Out);
Out.flush();
// If the thunk has been generated previously, just return it.
if (llvm::GlobalValue *GV = CGM.getModule().getNamedValue(ThunkName))
return cast<llvm::Function>(GV);
// Create the llvm::Function.
const CGFunctionInfo &FnInfo = CGM.getTypes().arrangeGlobalDeclaration(MD);
llvm::FunctionType *ThunkTy = CGM.getTypes().GetFunctionType(FnInfo);
llvm::Function *ThunkFn =
llvm::Function::Create(ThunkTy, llvm::Function::ExternalLinkage,
ThunkName.str(), &CGM.getModule());
assert(ThunkFn->getName() == ThunkName && "name was uniqued!");
ThunkFn->setLinkage(MD->isExternallyVisible()
? llvm::GlobalValue::LinkOnceODRLinkage
: llvm::GlobalValue::InternalLinkage);
CGM.SetLLVMFunctionAttributes(MD, FnInfo, ThunkFn);
CGM.SetLLVMFunctionAttributesForDefinition(MD, ThunkFn);
// Start codegen.
CodeGenFunction CGF(CGM);
CGF.StartThunk(ThunkFn, MD, FnInfo);
// Load the vfptr and then callee from the vftable. The callee should have
// adjusted 'this' so that the vfptr is at offset zero.
llvm::Value *This = CGF.LoadCXXThis();
llvm::Value *VTable =
CGF.GetVTablePtr(This, ThunkTy->getPointerTo()->getPointerTo());
llvm::Value *VFuncPtr =
CGF.Builder.CreateConstInBoundsGEP1_64(VTable, ML.Index, "vfn");
llvm::Value *Callee = CGF.Builder.CreateLoad(VFuncPtr);
unsigned CallingConv;
CodeGen::AttributeListType AttributeList;
CGM.ConstructAttributeList(FnInfo, MD, AttributeList, CallingConv, true);
llvm::AttributeSet Attrs =
llvm::AttributeSet::get(CGF.getLLVMContext(), AttributeList);
// Do a musttail call with perfect argument forwarding. Any inalloca argument
// will be forwarded in place without any copy.
SmallVector<llvm::Value *, 8> Args;
for (llvm::Argument &A : ThunkFn->args())
Args.push_back(&A);
llvm::CallInst *Call = CGF.Builder.CreateCall(Callee, Args);
Call->setTailCallKind(llvm::CallInst::TCK_MustTail);
Call->setAttributes(Attrs);
Call->setCallingConv(static_cast<llvm::CallingConv::ID>(CallingConv));
if (Call->getType()->isVoidTy())
CGF.Builder.CreateRetVoid();
else
CGF.Builder.CreateRet(Call);
// Finish the function to maintain CodeGenFunction invariants.
// FIXME: Don't emit unreachable code.
CGF.EmitBlock(CGF.createBasicBlock());
CGF.FinishFunction();
return ThunkFn;
}
void MicrosoftCXXABI::emitVirtualInheritanceTables(const CXXRecordDecl *RD) {
const VBTableGlobals &VBGlobals = enumerateVBTables(RD);
for (unsigned I = 0, E = VBGlobals.VBTables->size(); I != E; ++I) {
const VPtrInfo *VBT = (*VBGlobals.VBTables)[I];
llvm::GlobalVariable *GV = VBGlobals.Globals[I];
emitVBTableDefinition(*VBT, RD, GV);
}
}
llvm::GlobalVariable *
MicrosoftCXXABI::getAddrOfVBTable(const VPtrInfo &VBT, const CXXRecordDecl *RD,
llvm::GlobalVariable::LinkageTypes Linkage) {
SmallString<256> OutName;
llvm::raw_svector_ostream Out(OutName);
MicrosoftMangleContext &Mangler =
cast<MicrosoftMangleContext>(CGM.getCXXABI().getMangleContext());
Mangler.mangleCXXVBTable(RD, VBT.MangledPath, Out);
Out.flush();
StringRef Name = OutName.str();
llvm::ArrayType *VBTableType =
llvm::ArrayType::get(CGM.IntTy, 1 + VBT.ReusingBase->getNumVBases());
assert(!CGM.getModule().getNamedGlobal(Name) &&
"vbtable with this name already exists: mangling bug?");
llvm::GlobalVariable *GV =
CGM.CreateOrReplaceCXXRuntimeVariable(Name, VBTableType, Linkage);
GV->setUnnamedAddr(true);
if (RD->hasAttr<DLLImportAttr>())
GV->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass);
else if (RD->hasAttr<DLLExportAttr>())
GV->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);
return GV;
}
void MicrosoftCXXABI::emitVBTableDefinition(const VPtrInfo &VBT,
const CXXRecordDecl *RD,
llvm::GlobalVariable *GV) const {
const CXXRecordDecl *ReusingBase = VBT.ReusingBase;
assert(RD->getNumVBases() && ReusingBase->getNumVBases() &&
"should only emit vbtables for classes with vbtables");
const ASTRecordLayout &BaseLayout =
CGM.getContext().getASTRecordLayout(VBT.BaseWithVPtr);
const ASTRecordLayout &DerivedLayout =
CGM.getContext().getASTRecordLayout(RD);
SmallVector<llvm::Constant *, 4> Offsets(1 + ReusingBase->getNumVBases(),
nullptr);
// The offset from ReusingBase's vbptr to itself always leads.
CharUnits VBPtrOffset = BaseLayout.getVBPtrOffset();
Offsets[0] = llvm::ConstantInt::get(CGM.IntTy, -VBPtrOffset.getQuantity());
MicrosoftVTableContext &Context = CGM.getMicrosoftVTableContext();
for (const auto &I : ReusingBase->vbases()) {
const CXXRecordDecl *VBase = I.getType()->getAsCXXRecordDecl();
CharUnits Offset = DerivedLayout.getVBaseClassOffset(VBase);
assert(!Offset.isNegative());
// Make it relative to the subobject vbptr.
CharUnits CompleteVBPtrOffset = VBT.NonVirtualOffset + VBPtrOffset;
if (VBT.getVBaseWithVPtr())
CompleteVBPtrOffset +=
DerivedLayout.getVBaseClassOffset(VBT.getVBaseWithVPtr());
Offset -= CompleteVBPtrOffset;
unsigned VBIndex = Context.getVBTableIndex(ReusingBase, VBase);
assert(Offsets[VBIndex] == nullptr && "The same vbindex seen twice?");
Offsets[VBIndex] = llvm::ConstantInt::get(CGM.IntTy, Offset.getQuantity());
}
assert(Offsets.size() ==
cast<llvm::ArrayType>(cast<llvm::PointerType>(GV->getType())
->getElementType())->getNumElements());
llvm::ArrayType *VBTableType =
llvm::ArrayType::get(CGM.IntTy, Offsets.size());
llvm::Constant *Init = llvm::ConstantArray::get(VBTableType, Offsets);
GV->setInitializer(Init);
// Set the right visibility.
CGM.setGlobalVisibility(GV, RD);
}
llvm::Value *MicrosoftCXXABI::performThisAdjustment(CodeGenFunction &CGF,
llvm::Value *This,
const ThisAdjustment &TA) {
if (TA.isEmpty())
return This;
llvm::Value *V = CGF.Builder.CreateBitCast(This, CGF.Int8PtrTy);
if (!TA.Virtual.isEmpty()) {
assert(TA.Virtual.Microsoft.VtordispOffset < 0);
// Adjust the this argument based on the vtordisp value.
llvm::Value *VtorDispPtr =
CGF.Builder.CreateConstGEP1_32(V, TA.Virtual.Microsoft.VtordispOffset);
VtorDispPtr =
CGF.Builder.CreateBitCast(VtorDispPtr, CGF.Int32Ty->getPointerTo());
llvm::Value *VtorDisp = CGF.Builder.CreateLoad(VtorDispPtr, "vtordisp");
V = CGF.Builder.CreateGEP(V, CGF.Builder.CreateNeg(VtorDisp));
if (TA.Virtual.Microsoft.VBPtrOffset) {
// If the final overrider is defined in a virtual base other than the one
// that holds the vfptr, we have to use a vtordispex thunk which looks up
// the vbtable of the derived class.
assert(TA.Virtual.Microsoft.VBPtrOffset > 0);
assert(TA.Virtual.Microsoft.VBOffsetOffset >= 0);
llvm::Value *VBPtr;
llvm::Value *VBaseOffset =
GetVBaseOffsetFromVBPtr(CGF, V, -TA.Virtual.Microsoft.VBPtrOffset,
TA.Virtual.Microsoft.VBOffsetOffset, &VBPtr);
V = CGF.Builder.CreateInBoundsGEP(VBPtr, VBaseOffset);
}
}
if (TA.NonVirtual) {
// Non-virtual adjustment might result in a pointer outside the allocated
// object, e.g. if the final overrider class is laid out after the virtual
// base that declares a method in the most derived class.
V = CGF.Builder.CreateConstGEP1_32(V, TA.NonVirtual);
}
// Don't need to bitcast back, the call CodeGen will handle this.
return V;
}
llvm::Value *
MicrosoftCXXABI::performReturnAdjustment(CodeGenFunction &CGF, llvm::Value *Ret,
const ReturnAdjustment &RA) {
if (RA.isEmpty())
return Ret;
llvm::Value *V = CGF.Builder.CreateBitCast(Ret, CGF.Int8PtrTy);
if (RA.Virtual.Microsoft.VBIndex) {
assert(RA.Virtual.Microsoft.VBIndex > 0);
int32_t IntSize =
getContext().getTypeSizeInChars(getContext().IntTy).getQuantity();
llvm::Value *VBPtr;
llvm::Value *VBaseOffset =
GetVBaseOffsetFromVBPtr(CGF, V, RA.Virtual.Microsoft.VBPtrOffset,
IntSize * RA.Virtual.Microsoft.VBIndex, &VBPtr);
V = CGF.Builder.CreateInBoundsGEP(VBPtr, VBaseOffset);
}
if (RA.NonVirtual)
V = CGF.Builder.CreateConstInBoundsGEP1_32(V, RA.NonVirtual);
// Cast back to the original type.
return CGF.Builder.CreateBitCast(V, Ret->getType());
}
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 *GV,
bool PerformInit) {
// MSVC only uses guards for static locals.
if (!D.isStaticLocal()) {
assert(GV->hasWeakLinkage() || GV->hasLinkOnceLinkage());
// GlobalOpt is allowed to discard the initializer, so use linkonce_odr.
CGF.CurFn->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage);
CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit);
return;
}
// MSVC always uses an i32 bitfield to guard initialization, which is *not*
// threadsafe. Since the user may be linking in inline functions compiled by
// cl.exe, there's no reason to provide a false sense of security by using
// critical sections here.
if (D.getTLSKind())
CGM.ErrorUnsupported(&D, "dynamic TLS initialization");
CGBuilderTy &Builder = CGF.Builder;
llvm::IntegerType *GuardTy = CGF.Int32Ty;
llvm::ConstantInt *Zero = llvm::ConstantInt::get(GuardTy, 0);
// Get the guard variable for this function if we have one already.
GuardInfo *GI = &GuardVariableMap[D.getDeclContext()];
unsigned BitIndex;
if (D.isStaticLocal() && D.isExternallyVisible()) {
// Externally visible variables have to be numbered in Sema to properly
// handle unreachable VarDecls.
BitIndex = getContext().getStaticLocalNumber(&D);
assert(BitIndex > 0);
BitIndex--;
} else {
// Non-externally visible variables are numbered here in CodeGen.
BitIndex = GI->BitIndex++;
}
if (BitIndex >= 32) {
if (D.isExternallyVisible())
ErrorUnsupportedABI(CGF, "more than 32 guarded initializations");
BitIndex %= 32;
GI->Guard = nullptr;
}
// Lazily create the i32 bitfield for this function.
if (!GI->Guard) {
// Mangle the name for the guard.
SmallString<256> GuardName;
{
llvm::raw_svector_ostream Out(GuardName);
getMangleContext().mangleStaticGuardVariable(&D, Out);
Out.flush();
}
// Create the guard variable with a zero-initializer. Just absorb linkage
// and visibility from the guarded variable.
GI->Guard =
new llvm::GlobalVariable(CGM.getModule(), GuardTy, false,
GV->getLinkage(), Zero, GuardName.str());
GI->Guard->setVisibility(GV->getVisibility());
} else {
assert(GI->Guard->getLinkage() == GV->getLinkage() &&
"static local from the same function had different linkage");
}
// Pseudo code for the test:
// if (!(GuardVar & MyGuardBit)) {
// GuardVar |= MyGuardBit;
// ... initialize the object ...;
// }
// Test our bit from the guard variable.
llvm::ConstantInt *Bit = llvm::ConstantInt::get(GuardTy, 1U << BitIndex);
llvm::LoadInst *LI = Builder.CreateLoad(GI->Guard);
llvm::Value *IsInitialized =
Builder.CreateICmpNE(Builder.CreateAnd(LI, Bit), Zero);
llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init");
llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end");
Builder.CreateCondBr(IsInitialized, EndBlock, InitBlock);
// Set our bit in the guard variable and emit the initializer and add a global
// destructor if appropriate.
CGF.EmitBlock(InitBlock);
Builder.CreateStore(Builder.CreateOr(LI, Bit), GI->Guard);
CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit);
Builder.CreateBr(EndBlock);
// Continue.
CGF.EmitBlock(EndBlock);
}
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->getMostRecentCXXRecordDecl();
MSInheritanceAttr::Spelling Inheritance = RD->getMSInheritanceModel();
return (!MSInheritanceAttr::hasVBTableOffsetField(Inheritance) &&
RD->nullFieldOffsetIsZero());
}
llvm::Type *
MicrosoftCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) {
const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
MSInheritanceAttr::Spelling 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 (MSInheritanceAttr::hasNVOffsetField(MPT->isMemberFunctionPointer(),
Inheritance))
fields.push_back(CGM.IntTy);
if (MSInheritanceAttr::hasVBPtrOffsetField(Inheritance))
fields.push_back(CGM.IntTy);
if (MSInheritanceAttr::hasVBTableOffsetField(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->getMostRecentCXXRecordDecl();
MSInheritanceAttr::Spelling Inheritance = RD->getMSInheritanceModel();
if (MPT->isMemberFunctionPointer()) {
// FunctionPointerOrVirtualThunk
fields.push_back(llvm::Constant::getNullValue(CGM.VoidPtrTy));
} else {
if (RD->nullFieldOffsetIsZero())
fields.push_back(getZeroInt()); // FieldOffset
else
fields.push_back(getAllOnesInt()); // FieldOffset
}
if (MSInheritanceAttr::hasNVOffsetField(MPT->isMemberFunctionPointer(),
Inheritance))
fields.push_back(getZeroInt());
if (MSInheritanceAttr::hasVBPtrOffsetField(Inheritance))
fields.push_back(getZeroInt());
if (MSInheritanceAttr::hasVBTableOffsetField(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)
{
MSInheritanceAttr::Spelling Inheritance = RD->getMSInheritanceModel();
// Single inheritance class member pointer are represented as scalars instead
// of aggregates.
if (MSInheritanceAttr::hasOnlyOneField(IsMemberFunction, Inheritance))
return FirstField;
llvm::SmallVector<llvm::Constant *, 4> fields;
fields.push_back(FirstField);
if (MSInheritanceAttr::hasNVOffsetField(IsMemberFunction, Inheritance))
fields.push_back(llvm::ConstantInt::get(
CGM.IntTy, NonVirtualBaseAdjustment.getQuantity()));
if (MSInheritanceAttr::hasVBPtrOffsetField(Inheritance)) {
CharUnits Offs = CharUnits::Zero();
if (RD->getNumVBases())
Offs = getContext().getASTRecordLayout(RD).getVBPtrOffset();
fields.push_back(llvm::ConstantInt::get(CGM.IntTy, Offs.getQuantity()));
}
// The rest of the fields are adjusted by conversions to a more derived class.
if (MSInheritanceAttr::hasVBTableOffsetField(Inheritance))
fields.push_back(getZeroInt());
return llvm::ConstantStruct::getAnon(fields);
}
llvm::Constant *
MicrosoftCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT,
CharUnits offset) {
const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
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->getMostRecentCXXRecordDecl(), 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();
RD = RD->getMostRecentDecl();
CodeGenTypes &Types = CGM.getTypes();
llvm::Constant *FirstField;
if (!MD->isVirtual()) {
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);
} else {
MicrosoftVTableContext::MethodVFTableLocation ML =
CGM.getMicrosoftVTableContext().getMethodVFTableLocation(MD);
if (MD->isVariadic()) {
CGM.ErrorUnsupported(MD, "pointer to variadic virtual member function");
FirstField = llvm::Constant::getNullValue(CGM.VoidPtrTy);
} else if (!CGM.getTypes().isFuncTypeConvertible(
MD->getType()->castAs<FunctionType>())) {
CGM.ErrorUnsupported(MD, "pointer to virtual member function with "
"incomplete return or parameter type");
FirstField = llvm::Constant::getNullValue(CGM.VoidPtrTy);
} else if (ML.VBase) {
CGM.ErrorUnsupported(MD, "pointer to virtual member function overriding "
"member function in virtual base class");
FirstField = llvm::Constant::getNullValue(CGM.VoidPtrTy);
} else {
llvm::Function *Thunk = EmitVirtualMemPtrThunk(MD, ML);
FirstField = llvm::ConstantExpr::getBitCast(Thunk, CGM.VoidPtrTy);
// Include the vfptr adjustment if the method is in a non-primary vftable.
NonVirtualBaseAdjustment += ML.VFPtrOffset;
}
}
// 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->getMostRecentCXXRecordDecl();
MSInheritanceAttr::Spelling Inheritance = RD->getMSInheritanceModel();
if (MSInheritanceAttr::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 = nullptr;
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.CreateOr(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 *VBPtrOffset,
llvm::Value *VBTableOffset,
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 Expr *E, 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 = nullptr;
llvm::BasicBlock *SkipAdjustBB = nullptr;
llvm::BasicBlock *VBaseAdjustBB = nullptr;
// 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->hasDefinition()) {
DiagnosticsEngine &Diags = CGF.CGM.getDiags();
unsigned DiagID = Diags.getCustomDiagID(
DiagnosticsEngine::Error,
"member pointer representation requires a "
"complete class type for %0 to perform this expression");
Diags.Report(E->getExprLoc(), DiagID) << RD << E->getSourceRange();
} else if (RD->getNumVBases())
offs = getContext().getASTRecordLayout(RD).getVBPtrOffset();
VBPtrOffset = llvm::ConstantInt::get(CGM.IntTy, offs.getQuantity());
}
llvm::Value *VBPtr = nullptr;
llvm::Value *VBaseOffs =
GetVBaseOffsetFromVBPtr(CGF, Base, VBPtrOffset, VBTableOffset, &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, const Expr *E, 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->getMostRecentCXXRecordDecl();
MSInheritanceAttr::Spelling 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 = nullptr;
llvm::Value *VBPtrOffset = nullptr;
if (MemPtr->getType()->isStructTy()) {
// We need to extract values.
unsigned I = 0;
FieldOffset = Builder.CreateExtractValue(MemPtr, I++);
if (MSInheritanceAttr::hasVBPtrOffsetField(Inheritance))
VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++);
if (MSInheritanceAttr::hasVBTableOffsetField(Inheritance))
VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++);
}
if (VirtualBaseAdjustmentOffset) {
Base = AdjustVirtualBase(CGF, E, RD, Base, VirtualBaseAdjustmentOffset,
VBPtrOffset);
}
// Cast to char*.
Base = Builder.CreateBitCast(Base, Builder.getInt8Ty()->getPointerTo(AS));
// Apply the offset, which we assume is non-null.
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 MSInheritanceAttr::Spelling
getInheritanceFromMemptr(const MemberPointerType *MPT) {
return MPT->getMostRecentCXXRecordDecl()->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>();
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)
return Src;
CXXRecordDecl *SrcRD = SrcTy->getMostRecentCXXRecordDecl();
CXXRecordDecl *DstRD = DstTy->getMostRecentCXXRecordDecl();
if (IsReinterpret &&
SrcRD->nullFieldOffsetIsZero() == DstRD->nullFieldOffsetIsZero())
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 = nullptr;
llvm::Value *VirtualBaseAdjustmentOffset = nullptr;
llvm::Value *VBPtrOffset = nullptr;
MSInheritanceAttr::Spelling SrcInheritance = SrcRD->getMSInheritanceModel();
if (!MSInheritanceAttr::hasOnlyOneField(IsFunc, SrcInheritance)) {
// We need to extract values.
unsigned I = 0;
FirstField = Builder.CreateExtractValue(Src, I++);
if (MSInheritanceAttr::hasNVOffsetField(IsFunc, SrcInheritance))
NonVirtualBaseAdjustment = Builder.CreateExtractValue(Src, I++);
if (MSInheritanceAttr::hasVBPtrOffsetField(SrcInheritance))
VBPtrOffset = Builder.CreateExtractValue(Src, I++);
if (MSInheritanceAttr::hasVBTableOffsetField(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.
MSInheritanceAttr::Spelling DstInheritance = DstRD->getMSInheritanceModel();
llvm::Value *Dst;
if (MSInheritanceAttr::hasOnlyOneField(IsFunc, DstInheritance)) {
Dst = FirstField;
} else {
Dst = llvm::UndefValue::get(DstNull->getType());
unsigned Idx = 0;
Dst = Builder.CreateInsertValue(Dst, FirstField, Idx++);
if (MSInheritanceAttr::hasNVOffsetField(IsFunc, DstInheritance))
Dst = Builder.CreateInsertValue(
Dst, getValueOrZeroInt(NonVirtualBaseAdjustment), Idx++);
if (MSInheritanceAttr::hasVBPtrOffsetField(DstInheritance))
Dst = Builder.CreateInsertValue(
Dst, getValueOrZeroInt(VBPtrOffset), Idx++);
if (MSInheritanceAttr::hasVBTableOffsetField(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;
MSInheritanceAttr::Spelling SrcInheritance = getInheritanceFromMemptr(SrcTy);
MSInheritanceAttr::Spelling DstInheritance = getInheritanceFromMemptr(DstTy);
// Decompose src.
llvm::Constant *FirstField = Src;
llvm::Constant *NonVirtualBaseAdjustment = nullptr;
llvm::Constant *VirtualBaseAdjustmentOffset = nullptr;
llvm::Constant *VBPtrOffset = nullptr;
bool IsFunc = SrcTy->isMemberFunctionPointer();
if (!MSInheritanceAttr::hasOnlyOneField(IsFunc, SrcInheritance)) {
// We need to extract values.
unsigned I = 0;
FirstField = Src->getAggregateElement(I++);
if (MSInheritanceAttr::hasNVOffsetField(IsFunc, SrcInheritance))
NonVirtualBaseAdjustment = Src->getAggregateElement(I++);
if (MSInheritanceAttr::hasVBPtrOffsetField(SrcInheritance))
VBPtrOffset = Src->getAggregateElement(I++);
if (MSInheritanceAttr::hasVBTableOffsetField(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 (MSInheritanceAttr::hasOnlyOneField(IsFunc, DstInheritance))
return FirstField;
llvm::SmallVector<llvm::Constant *, 4> Fields;
Fields.push_back(FirstField);
if (MSInheritanceAttr::hasNVOffsetField(IsFunc, DstInheritance))
Fields.push_back(getConstantOrZeroInt(NonVirtualBaseAdjustment));
if (MSInheritanceAttr::hasVBPtrOffsetField(DstInheritance))
Fields.push_back(getConstantOrZeroInt(VBPtrOffset));
if (MSInheritanceAttr::hasVBTableOffsetField(DstInheritance))
Fields.push_back(getConstantOrZeroInt(VirtualBaseAdjustmentOffset));
return llvm::ConstantStruct::getAnon(Fields);
}
llvm::Value *MicrosoftCXXABI::EmitLoadOfMemberFunctionPointer(
CodeGenFunction &CGF, const Expr *E, llvm::Value *&This,
llvm::Value *MemPtr, const MemberPointerType *MPT) {
assert(MPT->isMemberFunctionPointer());
const FunctionProtoType *FPT =
MPT->getPointeeType()->castAs<FunctionProtoType>();
const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
llvm::FunctionType *FTy =
CGM.getTypes().GetFunctionType(
CGM.getTypes().arrangeCXXMethodType(RD, FPT));
CGBuilderTy &Builder = CGF.Builder;
MSInheritanceAttr::Spelling 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 = nullptr;
llvm::Value *VirtualBaseAdjustmentOffset = nullptr;
llvm::Value *VBPtrOffset = nullptr;
if (MemPtr->getType()->isStructTy()) {
// We need to extract values.
unsigned I = 0;
FunctionPointer = Builder.CreateExtractValue(MemPtr, I++);
if (MSInheritanceAttr::hasNVOffsetField(MPT, Inheritance))
NonVirtualBaseAdjustment = Builder.CreateExtractValue(MemPtr, I++);
if (MSInheritanceAttr::hasVBPtrOffsetField(Inheritance))
VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++);
if (MSInheritanceAttr::hasVBTableOffsetField(Inheritance))
VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++);
}
if (VirtualBaseAdjustmentOffset) {
This = AdjustVirtualBase(CGF, E, 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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