1 //===----- CGCXXABI.cpp - Interface to C++ ABIs -----------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This provides an abstract class for C++ code generation. Concrete subclasses 11 // of this implement code generation for specific C++ ABIs. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "CGCXXABI.h" 16 17 using namespace clang; 18 using namespace CodeGen; 19 20 CGCXXABI::~CGCXXABI() { } 21 22 void CGCXXABI::ErrorUnsupportedABI(CodeGenFunction &CGF, StringRef S) { 23 DiagnosticsEngine &Diags = CGF.CGM.getDiags(); 24 unsigned DiagID = Diags.getCustomDiagID(DiagnosticsEngine::Error, 25 "cannot yet compile %0 in this ABI"); 26 Diags.Report(CGF.getContext().getFullLoc(CGF.CurCodeDecl->getLocation()), 27 DiagID) 28 << S; 29 } 30 31 llvm::Constant *CGCXXABI::GetBogusMemberPointer(QualType T) { 32 return llvm::Constant::getNullValue(CGM.getTypes().ConvertType(T)); 33 } 34 35 llvm::Type * 36 CGCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) { 37 return CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType()); 38 } 39 40 llvm::Value *CGCXXABI::EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, 41 llvm::Value *&This, 42 llvm::Value *MemPtr, 43 const MemberPointerType *MPT) { 44 ErrorUnsupportedABI(CGF, "calls through member pointers"); 45 46 const FunctionProtoType *FPT = 47 MPT->getPointeeType()->getAs<FunctionProtoType>(); 48 const CXXRecordDecl *RD = 49 cast<CXXRecordDecl>(MPT->getClass()->getAs<RecordType>()->getDecl()); 50 llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType( 51 CGM.getTypes().arrangeCXXMethodType(RD, FPT)); 52 return llvm::Constant::getNullValue(FTy->getPointerTo()); 53 } 54 55 llvm::Value *CGCXXABI::EmitMemberDataPointerAddress(CodeGenFunction &CGF, 56 llvm::Value *Base, 57 llvm::Value *MemPtr, 58 const MemberPointerType *MPT) { 59 ErrorUnsupportedABI(CGF, "loads of member pointers"); 60 llvm::Type *Ty = CGF.ConvertType(MPT->getPointeeType())->getPointerTo(); 61 return llvm::Constant::getNullValue(Ty); 62 } 63 64 llvm::Value *CGCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF, 65 const CastExpr *E, 66 llvm::Value *Src) { 67 ErrorUnsupportedABI(CGF, "member function pointer conversions"); 68 return GetBogusMemberPointer(E->getType()); 69 } 70 71 llvm::Constant *CGCXXABI::EmitMemberPointerConversion(const CastExpr *E, 72 llvm::Constant *Src) { 73 return GetBogusMemberPointer(E->getType()); 74 } 75 76 llvm::Value * 77 CGCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF, 78 llvm::Value *L, 79 llvm::Value *R, 80 const MemberPointerType *MPT, 81 bool Inequality) { 82 ErrorUnsupportedABI(CGF, "member function pointer comparison"); 83 return CGF.Builder.getFalse(); 84 } 85 86 llvm::Value * 87 CGCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF, 88 llvm::Value *MemPtr, 89 const MemberPointerType *MPT) { 90 ErrorUnsupportedABI(CGF, "member function pointer null testing"); 91 return CGF.Builder.getFalse(); 92 } 93 94 llvm::Constant * 95 CGCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) { 96 return GetBogusMemberPointer(QualType(MPT, 0)); 97 } 98 99 llvm::Constant *CGCXXABI::EmitMemberPointer(const CXXMethodDecl *MD) { 100 return GetBogusMemberPointer( 101 CGM.getContext().getMemberPointerType(MD->getType(), 102 MD->getParent()->getTypeForDecl())); 103 } 104 105 llvm::Constant *CGCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT, 106 CharUnits offset) { 107 return GetBogusMemberPointer(QualType(MPT, 0)); 108 } 109 110 llvm::Constant *CGCXXABI::EmitMemberPointer(const APValue &MP, QualType MPT) { 111 return GetBogusMemberPointer(MPT); 112 } 113 114 bool CGCXXABI::isZeroInitializable(const MemberPointerType *MPT) { 115 // Fake answer. 116 return true; 117 } 118 119 void CGCXXABI::BuildThisParam(CodeGenFunction &CGF, FunctionArgList ¶ms) { 120 const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl()); 121 122 // FIXME: I'm not entirely sure I like using a fake decl just for code 123 // generation. Maybe we can come up with a better way? 124 ImplicitParamDecl *ThisDecl 125 = ImplicitParamDecl::Create(CGM.getContext(), 0, MD->getLocation(), 126 &CGM.getContext().Idents.get("this"), 127 MD->getThisType(CGM.getContext())); 128 params.push_back(ThisDecl); 129 getThisDecl(CGF) = ThisDecl; 130 } 131 132 void CGCXXABI::EmitThisParam(CodeGenFunction &CGF) { 133 /// Initialize the 'this' slot. 134 assert(getThisDecl(CGF) && "no 'this' variable for function"); 135 getThisValue(CGF) 136 = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(getThisDecl(CGF)), 137 "this"); 138 } 139 140 void CGCXXABI::EmitReturnFromThunk(CodeGenFunction &CGF, 141 RValue RV, QualType ResultType) { 142 CGF.EmitReturnOfRValue(RV, ResultType); 143 } 144 145 CharUnits CGCXXABI::GetArrayCookieSize(const CXXNewExpr *expr) { 146 if (!requiresArrayCookie(expr)) 147 return CharUnits::Zero(); 148 return getArrayCookieSizeImpl(expr->getAllocatedType()); 149 } 150 151 CharUnits CGCXXABI::getArrayCookieSizeImpl(QualType elementType) { 152 // BOGUS 153 return CharUnits::Zero(); 154 } 155 156 llvm::Value *CGCXXABI::InitializeArrayCookie(CodeGenFunction &CGF, 157 llvm::Value *NewPtr, 158 llvm::Value *NumElements, 159 const CXXNewExpr *expr, 160 QualType ElementType) { 161 // Should never be called. 162 ErrorUnsupportedABI(CGF, "array cookie initialization"); 163 return 0; 164 } 165 166 bool CGCXXABI::requiresArrayCookie(const CXXDeleteExpr *expr, 167 QualType elementType) { 168 // If the class's usual deallocation function takes two arguments, 169 // it needs a cookie. 170 if (expr->doesUsualArrayDeleteWantSize()) 171 return true; 172 173 return elementType.isDestructedType(); 174 } 175 176 bool CGCXXABI::requiresArrayCookie(const CXXNewExpr *expr) { 177 // If the class's usual deallocation function takes two arguments, 178 // it needs a cookie. 179 if (expr->doesUsualArrayDeleteWantSize()) 180 return true; 181 182 return expr->getAllocatedType().isDestructedType(); 183 } 184 185 void CGCXXABI::ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *ptr, 186 const CXXDeleteExpr *expr, QualType eltTy, 187 llvm::Value *&numElements, 188 llvm::Value *&allocPtr, CharUnits &cookieSize) { 189 // Derive a char* in the same address space as the pointer. 190 unsigned AS = ptr->getType()->getPointerAddressSpace(); 191 llvm::Type *charPtrTy = CGF.Int8Ty->getPointerTo(AS); 192 ptr = CGF.Builder.CreateBitCast(ptr, charPtrTy); 193 194 // If we don't need an array cookie, bail out early. 195 if (!requiresArrayCookie(expr, eltTy)) { 196 allocPtr = ptr; 197 numElements = 0; 198 cookieSize = CharUnits::Zero(); 199 return; 200 } 201 202 cookieSize = getArrayCookieSizeImpl(eltTy); 203 allocPtr = CGF.Builder.CreateConstInBoundsGEP1_64(ptr, 204 -cookieSize.getQuantity()); 205 numElements = readArrayCookieImpl(CGF, allocPtr, cookieSize); 206 } 207 208 llvm::Value *CGCXXABI::readArrayCookieImpl(CodeGenFunction &CGF, 209 llvm::Value *ptr, 210 CharUnits cookieSize) { 211 ErrorUnsupportedABI(CGF, "reading a new[] cookie"); 212 return llvm::ConstantInt::get(CGF.SizeTy, 0); 213 } 214 215 void CGCXXABI::EmitGuardedInit(CodeGenFunction &CGF, 216 const VarDecl &D, 217 llvm::GlobalVariable *GV, 218 bool PerformInit) { 219 ErrorUnsupportedABI(CGF, "static local variable initialization"); 220 } 221 222 void CGCXXABI::registerGlobalDtor(CodeGenFunction &CGF, 223 const VarDecl &D, 224 llvm::Constant *dtor, 225 llvm::Constant *addr) { 226 if (D.getTLSKind()) 227 CGM.ErrorUnsupported(&D, "non-trivial TLS destruction"); 228 229 // The default behavior is to use atexit. 230 CGF.registerGlobalDtorWithAtExit(dtor, addr); 231 } 232 233 /// Returns the adjustment, in bytes, required for the given 234 /// member-pointer operation. Returns null if no adjustment is 235 /// required. 236 llvm::Constant *CGCXXABI::getMemberPointerAdjustment(const CastExpr *E) { 237 assert(E->getCastKind() == CK_DerivedToBaseMemberPointer || 238 E->getCastKind() == CK_BaseToDerivedMemberPointer); 239 240 QualType derivedType; 241 if (E->getCastKind() == CK_DerivedToBaseMemberPointer) 242 derivedType = E->getSubExpr()->getType(); 243 else 244 derivedType = E->getType(); 245 246 const CXXRecordDecl *derivedClass = 247 derivedType->castAs<MemberPointerType>()->getClass()->getAsCXXRecordDecl(); 248 249 return CGM.GetNonVirtualBaseClassOffset(derivedClass, 250 E->path_begin(), 251 E->path_end()); 252 } 253 254 CharUnits CGCXXABI::getMemberPointerPathAdjustment(const APValue &MP) { 255 // TODO: Store base specifiers in APValue member pointer paths so we can 256 // easily reuse CGM.GetNonVirtualBaseClassOffset(). 257 const ValueDecl *MPD = MP.getMemberPointerDecl(); 258 CharUnits ThisAdjustment = CharUnits::Zero(); 259 ArrayRef<const CXXRecordDecl*> Path = MP.getMemberPointerPath(); 260 bool DerivedMember = MP.isMemberPointerToDerivedMember(); 261 const CXXRecordDecl *RD = cast<CXXRecordDecl>(MPD->getDeclContext()); 262 for (unsigned I = 0, N = Path.size(); I != N; ++I) { 263 const CXXRecordDecl *Base = RD; 264 const CXXRecordDecl *Derived = Path[I]; 265 if (DerivedMember) 266 std::swap(Base, Derived); 267 ThisAdjustment += 268 getContext().getASTRecordLayout(Derived).getBaseClassOffset(Base); 269 RD = Path[I]; 270 } 271 if (DerivedMember) 272 ThisAdjustment = -ThisAdjustment; 273 return ThisAdjustment; 274 } 275 276 llvm::BasicBlock * 277 CGCXXABI::EmitCtorCompleteObjectHandler(CodeGenFunction &CGF, 278 const CXXRecordDecl *RD) { 279 if (CGM.getTarget().getCXXABI().hasConstructorVariants()) 280 llvm_unreachable("shouldn't be called in this ABI"); 281 282 ErrorUnsupportedABI(CGF, "complete object detection in ctor"); 283 return 0; 284 } 285 286 void CGCXXABI::EmitThreadLocalInitFuncs( 287 llvm::ArrayRef<std::pair<const VarDecl *, llvm::GlobalVariable *> > Decls, 288 llvm::Function *InitFunc) { 289 } 290 291 LValue CGCXXABI::EmitThreadLocalDeclRefExpr(CodeGenFunction &CGF, 292 const DeclRefExpr *DRE) { 293 ErrorUnsupportedABI(CGF, "odr-use of thread_local global"); 294 return LValue(); 295 } 296 297 bool CGCXXABI::NeedsVTTParameter(GlobalDecl GD) { 298 return false; 299 } 300
