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//===----- CGCXXABI.cpp - Interface to C++ ABIs ---------------------------===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This provides an abstract class for C++ code generation. Concrete subclasses
// of this implement code generation for specific C++ ABIs.
#include "CGCXXABI.h"
#include "CGCleanup.h"
using namespace clang;
using namespace CodeGen;
void CGCXXABI::ErrorUnsupportedABI(CodeGenFunction &CGF, StringRef S) {
DiagnosticsEngine &Diags = CGF.CGM.getDiags();
unsigned DiagID = Diags.getCustomDiagID(DiagnosticsEngine::Error,
"cannot yet compile %0 in this ABI");
<< S;
bool CGCXXABI::canCopyArgument(const CXXRecordDecl *RD) const {
// If RD has a non-trivial move or copy constructor, we cannot copy the
// argument.
if (RD->hasNonTrivialCopyConstructor() || RD->hasNonTrivialMoveConstructor())
return false;
// If RD has a non-trivial destructor, we cannot copy the argument.
if (RD->hasNonTrivialDestructor())
return false;
// We can only copy the argument if there exists at least one trivial,
// non-deleted copy or move constructor.
// FIXME: This assumes that all lazily declared copy and move constructors are
// not deleted. This assumption might not be true in some corner cases.
bool CopyDeleted = false;
bool MoveDeleted = false;
for (const CXXConstructorDecl *CD : RD->ctors()) {
if (CD->isCopyConstructor() || CD->isMoveConstructor()) {
// We had at least one undeleted trivial copy or move ctor. Return
// directly.
if (!CD->isDeleted())
return true;
if (CD->isCopyConstructor())
CopyDeleted = true;
MoveDeleted = true;
// If all trivial copy and move constructors are deleted, we cannot copy the
// argument.
return !(CopyDeleted && MoveDeleted);
llvm::Constant *CGCXXABI::GetBogusMemberPointer(QualType T) {
return llvm::Constant::getNullValue(CGM.getTypes().ConvertType(T));
llvm::Type *
CGCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) {
return CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType());
llvm::Value *CGCXXABI::EmitLoadOfMemberFunctionPointer(
CodeGenFunction &CGF, const Expr *E, Address This,
llvm::Value *&ThisPtrForCall,
llvm::Value *MemPtr, const MemberPointerType *MPT) {
ErrorUnsupportedABI(CGF, "calls through member pointers");
ThisPtrForCall = This.getPointer();
const FunctionProtoType *FPT =
const CXXRecordDecl *RD =
llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(
CGM.getTypes().arrangeCXXMethodType(RD, FPT, /*FD=*/nullptr));
return llvm::Constant::getNullValue(FTy->getPointerTo());
llvm::Value *
CGCXXABI::EmitMemberDataPointerAddress(CodeGenFunction &CGF, const Expr *E,
Address Base, llvm::Value *MemPtr,
const MemberPointerType *MPT) {
ErrorUnsupportedABI(CGF, "loads of member pointers");
llvm::Type *Ty = CGF.ConvertType(MPT->getPointeeType())
return llvm::Constant::getNullValue(Ty);
llvm::Value *CGCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
const CastExpr *E,
llvm::Value *Src) {
ErrorUnsupportedABI(CGF, "member function pointer conversions");
return GetBogusMemberPointer(E->getType());
llvm::Constant *CGCXXABI::EmitMemberPointerConversion(const CastExpr *E,
llvm::Constant *Src) {
return GetBogusMemberPointer(E->getType());
llvm::Value *
CGCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF,
llvm::Value *L,
llvm::Value *R,
const MemberPointerType *MPT,
bool Inequality) {
ErrorUnsupportedABI(CGF, "member function pointer comparison");
return CGF.Builder.getFalse();
llvm::Value *
CGCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
llvm::Value *MemPtr,
const MemberPointerType *MPT) {
ErrorUnsupportedABI(CGF, "member function pointer null testing");
return CGF.Builder.getFalse();
llvm::Constant *
CGCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) {
return GetBogusMemberPointer(QualType(MPT, 0));
llvm::Constant *CGCXXABI::EmitMemberFunctionPointer(const CXXMethodDecl *MD) {
return GetBogusMemberPointer(CGM.getContext().getMemberPointerType(
MD->getType(), MD->getParent()->getTypeForDecl()));
llvm::Constant *CGCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT,
CharUnits offset) {
return GetBogusMemberPointer(QualType(MPT, 0));
llvm::Constant *CGCXXABI::EmitMemberPointer(const APValue &MP, QualType MPT) {
return GetBogusMemberPointer(MPT);
bool CGCXXABI::isZeroInitializable(const MemberPointerType *MPT) {
// Fake answer.
return true;
void CGCXXABI::buildThisParam(CodeGenFunction &CGF, FunctionArgList &params) {
const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
// FIXME: I'm not entirely sure I like using a fake decl just for code
// generation. Maybe we can come up with a better way?
ImplicitParamDecl *ThisDecl
= ImplicitParamDecl::Create(CGM.getContext(), nullptr, MD->getLocation(),
CGF.CXXABIThisDecl = ThisDecl;
// Compute the presumed alignment of 'this', which basically comes
// down to whether we know it's a complete object or not.
auto &Layout = CGF.getContext().getASTRecordLayout(MD->getParent());
if (MD->getParent()->getNumVBases() == 0 || // avoid vcall in common case
MD->getParent()->hasAttr<FinalAttr>() ||
!isThisCompleteObject(CGF.CurGD)) {
CGF.CXXABIThisAlignment = Layout.getAlignment();
} else {
CGF.CXXABIThisAlignment = Layout.getNonVirtualAlignment();
void CGCXXABI::EmitThisParam(CodeGenFunction &CGF) {
/// Initialize the 'this' slot.
assert(getThisDecl(CGF) && "no 'this' variable for function");
= CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(getThisDecl(CGF)),
void CGCXXABI::EmitReturnFromThunk(CodeGenFunction &CGF,
RValue RV, QualType ResultType) {
CGF.EmitReturnOfRValue(RV, ResultType);
CharUnits CGCXXABI::GetArrayCookieSize(const CXXNewExpr *expr) {
if (!requiresArrayCookie(expr))
return CharUnits::Zero();
return getArrayCookieSizeImpl(expr->getAllocatedType());
CharUnits CGCXXABI::getArrayCookieSizeImpl(QualType elementType) {
return CharUnits::Zero();
Address CGCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,
Address NewPtr,
llvm::Value *NumElements,
const CXXNewExpr *expr,
QualType ElementType) {
// Should never be called.
ErrorUnsupportedABI(CGF, "array cookie initialization");
return Address::invalid();
bool CGCXXABI::requiresArrayCookie(const CXXDeleteExpr *expr,
QualType elementType) {
// If the class's usual deallocation function takes two arguments,
// it needs a cookie.
if (expr->doesUsualArrayDeleteWantSize())
return true;
return elementType.isDestructedType();
bool CGCXXABI::requiresArrayCookie(const CXXNewExpr *expr) {
// If the class's usual deallocation function takes two arguments,
// it needs a cookie.
if (expr->doesUsualArrayDeleteWantSize())
return true;
return expr->getAllocatedType().isDestructedType();
void CGCXXABI::ReadArrayCookie(CodeGenFunction &CGF, Address ptr,
const CXXDeleteExpr *expr, QualType eltTy,
llvm::Value *&numElements,
llvm::Value *&allocPtr, CharUnits &cookieSize) {
// Derive a char* in the same address space as the pointer.
ptr = CGF.Builder.CreateElementBitCast(ptr, CGF.Int8Ty);
// If we don't need an array cookie, bail out early.
if (!requiresArrayCookie(expr, eltTy)) {
allocPtr = ptr.getPointer();
numElements = nullptr;
cookieSize = CharUnits::Zero();
cookieSize = getArrayCookieSizeImpl(eltTy);
Address allocAddr =
CGF.Builder.CreateConstInBoundsByteGEP(ptr, -cookieSize);
allocPtr = allocAddr.getPointer();
numElements = readArrayCookieImpl(CGF, allocAddr, cookieSize);
llvm::Value *CGCXXABI::readArrayCookieImpl(CodeGenFunction &CGF,
Address ptr,
CharUnits cookieSize) {
ErrorUnsupportedABI(CGF, "reading a new[] cookie");
return llvm::ConstantInt::get(CGF.SizeTy, 0);
/// Returns the adjustment, in bytes, required for the given
/// member-pointer operation. Returns null if no adjustment is
/// required.
llvm::Constant *CGCXXABI::getMemberPointerAdjustment(const CastExpr *E) {
assert(E->getCastKind() == CK_DerivedToBaseMemberPointer ||
E->getCastKind() == CK_BaseToDerivedMemberPointer);
QualType derivedType;
if (E->getCastKind() == CK_DerivedToBaseMemberPointer)
derivedType = E->getSubExpr()->getType();
derivedType = E->getType();
const CXXRecordDecl *derivedClass =
return CGM.GetNonVirtualBaseClassOffset(derivedClass,
CharUnits CGCXXABI::getMemberPointerPathAdjustment(const APValue &MP) {
// TODO: Store base specifiers in APValue member pointer paths so we can
// easily reuse CGM.GetNonVirtualBaseClassOffset().
const ValueDecl *MPD = MP.getMemberPointerDecl();
CharUnits ThisAdjustment = CharUnits::Zero();
ArrayRef<const CXXRecordDecl*> Path = MP.getMemberPointerPath();
bool DerivedMember = MP.isMemberPointerToDerivedMember();
const CXXRecordDecl *RD = cast<CXXRecordDecl>(MPD->getDeclContext());
for (unsigned I = 0, N = Path.size(); I != N; ++I) {
const CXXRecordDecl *Base = RD;
const CXXRecordDecl *Derived = Path[I];
if (DerivedMember)
std::swap(Base, Derived);
ThisAdjustment +=
RD = Path[I];
if (DerivedMember)
ThisAdjustment = -ThisAdjustment;
return ThisAdjustment;
llvm::BasicBlock *
CGCXXABI::EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
const CXXRecordDecl *RD) {
if (CGM.getTarget().getCXXABI().hasConstructorVariants())
llvm_unreachable("shouldn't be called in this ABI");
ErrorUnsupportedABI(CGF, "complete object detection in ctor");
return nullptr;
bool CGCXXABI::NeedsVTTParameter(GlobalDecl GD) {
return false;
llvm::CallInst *
CGCXXABI::emitTerminateForUnexpectedException(CodeGenFunction &CGF,
llvm::Value *Exn) {
// Just call std::terminate and ignore the violating exception.
return CGF.EmitNounwindRuntimeCall(CGF.CGM.getTerminateFn());
CatchTypeInfo CGCXXABI::getCatchAllTypeInfo() {
return CatchTypeInfo{nullptr, 0};
std::vector<CharUnits> CGCXXABI::getVBPtrOffsets(const CXXRecordDecl *RD) {
return std::vector<CharUnits>();