1 //===----- CGCXXABI.cpp - Interface to C++ ABIs ---------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This provides an abstract class for C++ code generation. Concrete subclasses
11 // of this implement code generation for specific C++ ABIs.
13 //===----------------------------------------------------------------------===//
16 #include "CGCleanup.h"
18 using namespace clang;
19 using namespace CodeGen;
21 CGCXXABI::~CGCXXABI() { }
23 void CGCXXABI::ErrorUnsupportedABI(CodeGenFunction &CGF, StringRef S) {
24 DiagnosticsEngine &Diags = CGF.CGM.getDiags();
25 unsigned DiagID = Diags.getCustomDiagID(DiagnosticsEngine::Error,
26 "cannot yet compile %0 in this ABI");
27 Diags.Report(CGF.getContext().getFullLoc(CGF.CurCodeDecl->getLocation()),
32 bool CGCXXABI::canCopyArgument(const CXXRecordDecl *RD) const {
33 // If RD has a non-trivial move or copy constructor, we cannot copy the
35 if (RD->hasNonTrivialCopyConstructor() || RD->hasNonTrivialMoveConstructor())
38 // If RD has a non-trivial destructor, we cannot copy the argument.
39 if (RD->hasNonTrivialDestructor())
42 // We can only copy the argument if there exists at least one trivial,
43 // non-deleted copy or move constructor.
44 // FIXME: This assumes that all lazily declared copy and move constructors are
45 // not deleted. This assumption might not be true in some corner cases.
46 bool CopyDeleted = false;
47 bool MoveDeleted = false;
48 for (const CXXConstructorDecl *CD : RD->ctors()) {
49 if (CD->isCopyConstructor() || CD->isMoveConstructor()) {
50 assert(CD->isTrivial());
51 // We had at least one undeleted trivial copy or move ctor. Return
55 if (CD->isCopyConstructor())
62 // If all trivial copy and move constructors are deleted, we cannot copy the
64 return !(CopyDeleted && MoveDeleted);
67 llvm::Constant *CGCXXABI::GetBogusMemberPointer(QualType T) {
68 return llvm::Constant::getNullValue(CGM.getTypes().ConvertType(T));
72 CGCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) {
73 return CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType());
76 CGCallee CGCXXABI::EmitLoadOfMemberFunctionPointer(
77 CodeGenFunction &CGF, const Expr *E, Address This,
78 llvm::Value *&ThisPtrForCall,
79 llvm::Value *MemPtr, const MemberPointerType *MPT) {
80 ErrorUnsupportedABI(CGF, "calls through member pointers");
82 ThisPtrForCall = This.getPointer();
83 const FunctionProtoType *FPT =
84 MPT->getPointeeType()->getAs<FunctionProtoType>();
85 const CXXRecordDecl *RD =
86 cast<CXXRecordDecl>(MPT->getClass()->getAs<RecordType>()->getDecl());
87 llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(
88 CGM.getTypes().arrangeCXXMethodType(RD, FPT, /*FD=*/nullptr));
89 llvm::Constant *FnPtr = llvm::Constant::getNullValue(FTy->getPointerTo());
90 return CGCallee::forDirect(FnPtr, FPT);
94 CGCXXABI::EmitMemberDataPointerAddress(CodeGenFunction &CGF, const Expr *E,
95 Address Base, llvm::Value *MemPtr,
96 const MemberPointerType *MPT) {
97 ErrorUnsupportedABI(CGF, "loads of member pointers");
98 llvm::Type *Ty = CGF.ConvertType(MPT->getPointeeType())
99 ->getPointerTo(Base.getAddressSpace());
100 return llvm::Constant::getNullValue(Ty);
103 llvm::Value *CGCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
106 ErrorUnsupportedABI(CGF, "member function pointer conversions");
107 return GetBogusMemberPointer(E->getType());
110 llvm::Constant *CGCXXABI::EmitMemberPointerConversion(const CastExpr *E,
111 llvm::Constant *Src) {
112 return GetBogusMemberPointer(E->getType());
116 CGCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF,
119 const MemberPointerType *MPT,
121 ErrorUnsupportedABI(CGF, "member function pointer comparison");
122 return CGF.Builder.getFalse();
126 CGCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
128 const MemberPointerType *MPT) {
129 ErrorUnsupportedABI(CGF, "member function pointer null testing");
130 return CGF.Builder.getFalse();
134 CGCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) {
135 return GetBogusMemberPointer(QualType(MPT, 0));
138 llvm::Constant *CGCXXABI::EmitMemberFunctionPointer(const CXXMethodDecl *MD) {
139 return GetBogusMemberPointer(CGM.getContext().getMemberPointerType(
140 MD->getType(), MD->getParent()->getTypeForDecl()));
143 llvm::Constant *CGCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT,
145 return GetBogusMemberPointer(QualType(MPT, 0));
148 llvm::Constant *CGCXXABI::EmitMemberPointer(const APValue &MP, QualType MPT) {
149 return GetBogusMemberPointer(MPT);
152 bool CGCXXABI::isZeroInitializable(const MemberPointerType *MPT) {
157 void CGCXXABI::buildThisParam(CodeGenFunction &CGF, FunctionArgList ¶ms) {
158 const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
160 // FIXME: I'm not entirely sure I like using a fake decl just for code
161 // generation. Maybe we can come up with a better way?
162 ImplicitParamDecl *ThisDecl
163 = ImplicitParamDecl::Create(CGM.getContext(), nullptr, MD->getLocation(),
164 &CGM.getContext().Idents.get("this"),
165 MD->getThisType(CGM.getContext()));
166 params.push_back(ThisDecl);
167 CGF.CXXABIThisDecl = ThisDecl;
169 // Compute the presumed alignment of 'this', which basically comes
170 // down to whether we know it's a complete object or not.
171 auto &Layout = CGF.getContext().getASTRecordLayout(MD->getParent());
172 if (MD->getParent()->getNumVBases() == 0 || // avoid vcall in common case
173 MD->getParent()->hasAttr<FinalAttr>() ||
174 !isThisCompleteObject(CGF.CurGD)) {
175 CGF.CXXABIThisAlignment = Layout.getAlignment();
177 CGF.CXXABIThisAlignment = Layout.getNonVirtualAlignment();
181 void CGCXXABI::EmitThisParam(CodeGenFunction &CGF) {
182 /// Initialize the 'this' slot.
183 assert(getThisDecl(CGF) && "no 'this' variable for function");
185 = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(getThisDecl(CGF)),
189 void CGCXXABI::EmitReturnFromThunk(CodeGenFunction &CGF,
190 RValue RV, QualType ResultType) {
191 CGF.EmitReturnOfRValue(RV, ResultType);
194 CharUnits CGCXXABI::GetArrayCookieSize(const CXXNewExpr *expr) {
195 if (!requiresArrayCookie(expr))
196 return CharUnits::Zero();
197 return getArrayCookieSizeImpl(expr->getAllocatedType());
200 CharUnits CGCXXABI::getArrayCookieSizeImpl(QualType elementType) {
202 return CharUnits::Zero();
205 Address CGCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,
207 llvm::Value *NumElements,
208 const CXXNewExpr *expr,
209 QualType ElementType) {
210 // Should never be called.
211 ErrorUnsupportedABI(CGF, "array cookie initialization");
212 return Address::invalid();
215 bool CGCXXABI::requiresArrayCookie(const CXXDeleteExpr *expr,
216 QualType elementType) {
217 // If the class's usual deallocation function takes two arguments,
218 // it needs a cookie.
219 if (expr->doesUsualArrayDeleteWantSize())
222 return elementType.isDestructedType();
225 bool CGCXXABI::requiresArrayCookie(const CXXNewExpr *expr) {
226 // If the class's usual deallocation function takes two arguments,
227 // it needs a cookie.
228 if (expr->doesUsualArrayDeleteWantSize())
231 return expr->getAllocatedType().isDestructedType();
234 void CGCXXABI::ReadArrayCookie(CodeGenFunction &CGF, Address ptr,
235 const CXXDeleteExpr *expr, QualType eltTy,
236 llvm::Value *&numElements,
237 llvm::Value *&allocPtr, CharUnits &cookieSize) {
238 // Derive a char* in the same address space as the pointer.
239 ptr = CGF.Builder.CreateElementBitCast(ptr, CGF.Int8Ty);
241 // If we don't need an array cookie, bail out early.
242 if (!requiresArrayCookie(expr, eltTy)) {
243 allocPtr = ptr.getPointer();
244 numElements = nullptr;
245 cookieSize = CharUnits::Zero();
249 cookieSize = getArrayCookieSizeImpl(eltTy);
251 CGF.Builder.CreateConstInBoundsByteGEP(ptr, -cookieSize);
252 allocPtr = allocAddr.getPointer();
253 numElements = readArrayCookieImpl(CGF, allocAddr, cookieSize);
256 llvm::Value *CGCXXABI::readArrayCookieImpl(CodeGenFunction &CGF,
258 CharUnits cookieSize) {
259 ErrorUnsupportedABI(CGF, "reading a new[] cookie");
260 return llvm::ConstantInt::get(CGF.SizeTy, 0);
263 /// Returns the adjustment, in bytes, required for the given
264 /// member-pointer operation. Returns null if no adjustment is
266 llvm::Constant *CGCXXABI::getMemberPointerAdjustment(const CastExpr *E) {
267 assert(E->getCastKind() == CK_DerivedToBaseMemberPointer ||
268 E->getCastKind() == CK_BaseToDerivedMemberPointer);
270 QualType derivedType;
271 if (E->getCastKind() == CK_DerivedToBaseMemberPointer)
272 derivedType = E->getSubExpr()->getType();
274 derivedType = E->getType();
276 const CXXRecordDecl *derivedClass =
277 derivedType->castAs<MemberPointerType>()->getClass()->getAsCXXRecordDecl();
279 return CGM.GetNonVirtualBaseClassOffset(derivedClass,
284 CharUnits CGCXXABI::getMemberPointerPathAdjustment(const APValue &MP) {
285 // TODO: Store base specifiers in APValue member pointer paths so we can
286 // easily reuse CGM.GetNonVirtualBaseClassOffset().
287 const ValueDecl *MPD = MP.getMemberPointerDecl();
288 CharUnits ThisAdjustment = CharUnits::Zero();
289 ArrayRef<const CXXRecordDecl*> Path = MP.getMemberPointerPath();
290 bool DerivedMember = MP.isMemberPointerToDerivedMember();
291 const CXXRecordDecl *RD = cast<CXXRecordDecl>(MPD->getDeclContext());
292 for (unsigned I = 0, N = Path.size(); I != N; ++I) {
293 const CXXRecordDecl *Base = RD;
294 const CXXRecordDecl *Derived = Path[I];
296 std::swap(Base, Derived);
298 getContext().getASTRecordLayout(Derived).getBaseClassOffset(Base);
302 ThisAdjustment = -ThisAdjustment;
303 return ThisAdjustment;
307 CGCXXABI::EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
308 const CXXRecordDecl *RD) {
309 if (CGM.getTarget().getCXXABI().hasConstructorVariants())
310 llvm_unreachable("shouldn't be called in this ABI");
312 ErrorUnsupportedABI(CGF, "complete object detection in ctor");
316 bool CGCXXABI::NeedsVTTParameter(GlobalDecl GD) {
321 CGCXXABI::emitTerminateForUnexpectedException(CodeGenFunction &CGF,
323 // Just call std::terminate and ignore the violating exception.
324 return CGF.EmitNounwindRuntimeCall(CGF.CGM.getTerminateFn());
327 CatchTypeInfo CGCXXABI::getCatchAllTypeInfo() {
328 return CatchTypeInfo{nullptr, 0};
331 std::vector<CharUnits> CGCXXABI::getVBPtrOffsets(const CXXRecordDecl *RD) {
332 return std::vector<CharUnits>();