ItaniumCXXABI.cpp revision 263508
1//===------- ItaniumCXXABI.cpp - Emit LLVM Code from ASTs for a Module ----===// 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 C++ code generation targeting the Itanium C++ ABI. The class 11// in this file generates structures that follow the Itanium C++ ABI, which is 12// documented at: 13// http://www.codesourcery.com/public/cxx-abi/abi.html 14// http://www.codesourcery.com/public/cxx-abi/abi-eh.html 15// 16// It also supports the closely-related ARM ABI, documented at: 17// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0041c/IHI0041C_cppabi.pdf 18// 19//===----------------------------------------------------------------------===// 20 21#include "CGCXXABI.h" 22#include "CGRecordLayout.h" 23#include "CGVTables.h" 24#include "CodeGenFunction.h" 25#include "CodeGenModule.h" 26#include "clang/AST/Mangle.h" 27#include "clang/AST/Type.h" 28#include "llvm/IR/DataLayout.h" 29#include "llvm/IR/Intrinsics.h" 30#include "llvm/IR/Value.h" 31 32using namespace clang; 33using namespace CodeGen; 34 35namespace { 36class ItaniumCXXABI : public CodeGen::CGCXXABI { 37 /// VTables - All the vtables which have been defined. 38 llvm::DenseMap<const CXXRecordDecl *, llvm::GlobalVariable *> VTables; 39 40protected: 41 bool UseARMMethodPtrABI; 42 bool UseARMGuardVarABI; 43 44 ItaniumMangleContext &getMangleContext() { 45 return cast<ItaniumMangleContext>(CodeGen::CGCXXABI::getMangleContext()); 46 } 47 48public: 49 ItaniumCXXABI(CodeGen::CodeGenModule &CGM, 50 bool UseARMMethodPtrABI = false, 51 bool UseARMGuardVarABI = false) : 52 CGCXXABI(CGM), UseARMMethodPtrABI(UseARMMethodPtrABI), 53 UseARMGuardVarABI(UseARMGuardVarABI) { } 54 55 bool isReturnTypeIndirect(const CXXRecordDecl *RD) const { 56 // Structures with either a non-trivial destructor or a non-trivial 57 // copy constructor are always indirect. 58 return !RD->hasTrivialDestructor() || RD->hasNonTrivialCopyConstructor(); 59 } 60 61 RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const { 62 // Structures with either a non-trivial destructor or a non-trivial 63 // copy constructor are always indirect. 64 if (!RD->hasTrivialDestructor() || RD->hasNonTrivialCopyConstructor()) 65 return RAA_Indirect; 66 return RAA_Default; 67 } 68 69 bool isZeroInitializable(const MemberPointerType *MPT); 70 71 llvm::Type *ConvertMemberPointerType(const MemberPointerType *MPT); 72 73 llvm::Value *EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, 74 llvm::Value *&This, 75 llvm::Value *MemFnPtr, 76 const MemberPointerType *MPT); 77 78 llvm::Value *EmitMemberDataPointerAddress(CodeGenFunction &CGF, 79 llvm::Value *Base, 80 llvm::Value *MemPtr, 81 const MemberPointerType *MPT); 82 83 llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF, 84 const CastExpr *E, 85 llvm::Value *Src); 86 llvm::Constant *EmitMemberPointerConversion(const CastExpr *E, 87 llvm::Constant *Src); 88 89 llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT); 90 91 llvm::Constant *EmitMemberPointer(const CXXMethodDecl *MD); 92 llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT, 93 CharUnits offset); 94 llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT); 95 llvm::Constant *BuildMemberPointer(const CXXMethodDecl *MD, 96 CharUnits ThisAdjustment); 97 98 llvm::Value *EmitMemberPointerComparison(CodeGenFunction &CGF, 99 llvm::Value *L, 100 llvm::Value *R, 101 const MemberPointerType *MPT, 102 bool Inequality); 103 104 llvm::Value *EmitMemberPointerIsNotNull(CodeGenFunction &CGF, 105 llvm::Value *Addr, 106 const MemberPointerType *MPT); 107 108 llvm::Value *adjustToCompleteObject(CodeGenFunction &CGF, 109 llvm::Value *ptr, 110 QualType type); 111 112 llvm::Value *GetVirtualBaseClassOffset(CodeGenFunction &CGF, 113 llvm::Value *This, 114 const CXXRecordDecl *ClassDecl, 115 const CXXRecordDecl *BaseClassDecl); 116 117 void BuildConstructorSignature(const CXXConstructorDecl *Ctor, 118 CXXCtorType T, 119 CanQualType &ResTy, 120 SmallVectorImpl<CanQualType> &ArgTys); 121 122 void EmitCXXConstructors(const CXXConstructorDecl *D); 123 124 void BuildDestructorSignature(const CXXDestructorDecl *Dtor, 125 CXXDtorType T, 126 CanQualType &ResTy, 127 SmallVectorImpl<CanQualType> &ArgTys); 128 129 bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor, 130 CXXDtorType DT) const { 131 // Itanium does not emit any destructor variant as an inline thunk. 132 // Delegating may occur as an optimization, but all variants are either 133 // emitted with external linkage or as linkonce if they are inline and used. 134 return false; 135 } 136 137 void EmitCXXDestructors(const CXXDestructorDecl *D); 138 139 void BuildInstanceFunctionParams(CodeGenFunction &CGF, 140 QualType &ResTy, 141 FunctionArgList &Params); 142 143 void EmitInstanceFunctionProlog(CodeGenFunction &CGF); 144 145 void EmitConstructorCall(CodeGenFunction &CGF, 146 const CXXConstructorDecl *D, CXXCtorType Type, 147 bool ForVirtualBase, bool Delegating, 148 llvm::Value *This, 149 CallExpr::const_arg_iterator ArgBeg, 150 CallExpr::const_arg_iterator ArgEnd); 151 152 void emitVTableDefinitions(CodeGenVTables &CGVT, const CXXRecordDecl *RD); 153 154 llvm::Value *getVTableAddressPointInStructor( 155 CodeGenFunction &CGF, const CXXRecordDecl *VTableClass, 156 BaseSubobject Base, const CXXRecordDecl *NearestVBase, 157 bool &NeedsVirtualOffset); 158 159 llvm::Constant * 160 getVTableAddressPointForConstExpr(BaseSubobject Base, 161 const CXXRecordDecl *VTableClass); 162 163 llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD, 164 CharUnits VPtrOffset); 165 166 llvm::Value *getVirtualFunctionPointer(CodeGenFunction &CGF, GlobalDecl GD, 167 llvm::Value *This, llvm::Type *Ty); 168 169 void EmitVirtualDestructorCall(CodeGenFunction &CGF, 170 const CXXDestructorDecl *Dtor, 171 CXXDtorType DtorType, SourceLocation CallLoc, 172 llvm::Value *This); 173 174 void emitVirtualInheritanceTables(const CXXRecordDecl *RD); 175 176 void setThunkLinkage(llvm::Function *Thunk, bool ForVTable) { 177 // Allow inlining of thunks by emitting them with available_externally 178 // linkage together with vtables when needed. 179 if (ForVTable) 180 Thunk->setLinkage(llvm::GlobalValue::AvailableExternallyLinkage); 181 } 182 183 llvm::Value *performThisAdjustment(CodeGenFunction &CGF, llvm::Value *This, 184 const ThisAdjustment &TA); 185 186 llvm::Value *performReturnAdjustment(CodeGenFunction &CGF, llvm::Value *Ret, 187 const ReturnAdjustment &RA); 188 189 StringRef GetPureVirtualCallName() { return "__cxa_pure_virtual"; } 190 StringRef GetDeletedVirtualCallName() { return "__cxa_deleted_virtual"; } 191 192 CharUnits getArrayCookieSizeImpl(QualType elementType); 193 llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF, 194 llvm::Value *NewPtr, 195 llvm::Value *NumElements, 196 const CXXNewExpr *expr, 197 QualType ElementType); 198 llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF, 199 llvm::Value *allocPtr, 200 CharUnits cookieSize); 201 202 void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D, 203 llvm::GlobalVariable *DeclPtr, bool PerformInit); 204 void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D, 205 llvm::Constant *dtor, llvm::Constant *addr); 206 207 llvm::Function *getOrCreateThreadLocalWrapper(const VarDecl *VD, 208 llvm::GlobalVariable *Var); 209 void EmitThreadLocalInitFuncs( 210 llvm::ArrayRef<std::pair<const VarDecl *, llvm::GlobalVariable *> > Decls, 211 llvm::Function *InitFunc); 212 LValue EmitThreadLocalDeclRefExpr(CodeGenFunction &CGF, 213 const DeclRefExpr *DRE); 214 215 bool NeedsVTTParameter(GlobalDecl GD); 216}; 217 218class ARMCXXABI : public ItaniumCXXABI { 219public: 220 ARMCXXABI(CodeGen::CodeGenModule &CGM) : 221 ItaniumCXXABI(CGM, /* UseARMMethodPtrABI = */ true, 222 /* UseARMGuardVarABI = */ true) {} 223 224 bool HasThisReturn(GlobalDecl GD) const { 225 return (isa<CXXConstructorDecl>(GD.getDecl()) || ( 226 isa<CXXDestructorDecl>(GD.getDecl()) && 227 GD.getDtorType() != Dtor_Deleting)); 228 } 229 230 void EmitReturnFromThunk(CodeGenFunction &CGF, RValue RV, QualType ResTy); 231 232 CharUnits getArrayCookieSizeImpl(QualType elementType); 233 llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF, 234 llvm::Value *NewPtr, 235 llvm::Value *NumElements, 236 const CXXNewExpr *expr, 237 QualType ElementType); 238 llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF, llvm::Value *allocPtr, 239 CharUnits cookieSize); 240}; 241} 242 243CodeGen::CGCXXABI *CodeGen::CreateItaniumCXXABI(CodeGenModule &CGM) { 244 switch (CGM.getTarget().getCXXABI().getKind()) { 245 // For IR-generation purposes, there's no significant difference 246 // between the ARM and iOS ABIs. 247 case TargetCXXABI::GenericARM: 248 case TargetCXXABI::iOS: 249 return new ARMCXXABI(CGM); 250 251 // Note that AArch64 uses the generic ItaniumCXXABI class since it doesn't 252 // include the other 32-bit ARM oddities: constructor/destructor return values 253 // and array cookies. 254 case TargetCXXABI::GenericAArch64: 255 return new ItaniumCXXABI(CGM, /* UseARMMethodPtrABI = */ true, 256 /* UseARMGuardVarABI = */ true); 257 258 case TargetCXXABI::GenericItanium: 259 if (CGM.getContext().getTargetInfo().getTriple().getArch() 260 == llvm::Triple::le32) { 261 // For PNaCl, use ARM-style method pointers so that PNaCl code 262 // does not assume anything about the alignment of function 263 // pointers. 264 return new ItaniumCXXABI(CGM, /* UseARMMethodPtrABI = */ true, 265 /* UseARMGuardVarABI = */ false); 266 } 267 return new ItaniumCXXABI(CGM); 268 269 case TargetCXXABI::Microsoft: 270 llvm_unreachable("Microsoft ABI is not Itanium-based"); 271 } 272 llvm_unreachable("bad ABI kind"); 273} 274 275llvm::Type * 276ItaniumCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) { 277 if (MPT->isMemberDataPointer()) 278 return CGM.PtrDiffTy; 279 return llvm::StructType::get(CGM.PtrDiffTy, CGM.PtrDiffTy, NULL); 280} 281 282/// In the Itanium and ARM ABIs, method pointers have the form: 283/// struct { ptrdiff_t ptr; ptrdiff_t adj; } memptr; 284/// 285/// In the Itanium ABI: 286/// - method pointers are virtual if (memptr.ptr & 1) is nonzero 287/// - the this-adjustment is (memptr.adj) 288/// - the virtual offset is (memptr.ptr - 1) 289/// 290/// In the ARM ABI: 291/// - method pointers are virtual if (memptr.adj & 1) is nonzero 292/// - the this-adjustment is (memptr.adj >> 1) 293/// - the virtual offset is (memptr.ptr) 294/// ARM uses 'adj' for the virtual flag because Thumb functions 295/// may be only single-byte aligned. 296/// 297/// If the member is virtual, the adjusted 'this' pointer points 298/// to a vtable pointer from which the virtual offset is applied. 299/// 300/// If the member is non-virtual, memptr.ptr is the address of 301/// the function to call. 302llvm::Value * 303ItaniumCXXABI::EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, 304 llvm::Value *&This, 305 llvm::Value *MemFnPtr, 306 const MemberPointerType *MPT) { 307 CGBuilderTy &Builder = CGF.Builder; 308 309 const FunctionProtoType *FPT = 310 MPT->getPointeeType()->getAs<FunctionProtoType>(); 311 const CXXRecordDecl *RD = 312 cast<CXXRecordDecl>(MPT->getClass()->getAs<RecordType>()->getDecl()); 313 314 llvm::FunctionType *FTy = 315 CGM.getTypes().GetFunctionType( 316 CGM.getTypes().arrangeCXXMethodType(RD, FPT)); 317 318 llvm::Constant *ptrdiff_1 = llvm::ConstantInt::get(CGM.PtrDiffTy, 1); 319 320 llvm::BasicBlock *FnVirtual = CGF.createBasicBlock("memptr.virtual"); 321 llvm::BasicBlock *FnNonVirtual = CGF.createBasicBlock("memptr.nonvirtual"); 322 llvm::BasicBlock *FnEnd = CGF.createBasicBlock("memptr.end"); 323 324 // Extract memptr.adj, which is in the second field. 325 llvm::Value *RawAdj = Builder.CreateExtractValue(MemFnPtr, 1, "memptr.adj"); 326 327 // Compute the true adjustment. 328 llvm::Value *Adj = RawAdj; 329 if (UseARMMethodPtrABI) 330 Adj = Builder.CreateAShr(Adj, ptrdiff_1, "memptr.adj.shifted"); 331 332 // Apply the adjustment and cast back to the original struct type 333 // for consistency. 334 llvm::Value *Ptr = Builder.CreateBitCast(This, Builder.getInt8PtrTy()); 335 Ptr = Builder.CreateInBoundsGEP(Ptr, Adj); 336 This = Builder.CreateBitCast(Ptr, This->getType(), "this.adjusted"); 337 338 // Load the function pointer. 339 llvm::Value *FnAsInt = Builder.CreateExtractValue(MemFnPtr, 0, "memptr.ptr"); 340 341 // If the LSB in the function pointer is 1, the function pointer points to 342 // a virtual function. 343 llvm::Value *IsVirtual; 344 if (UseARMMethodPtrABI) 345 IsVirtual = Builder.CreateAnd(RawAdj, ptrdiff_1); 346 else 347 IsVirtual = Builder.CreateAnd(FnAsInt, ptrdiff_1); 348 IsVirtual = Builder.CreateIsNotNull(IsVirtual, "memptr.isvirtual"); 349 Builder.CreateCondBr(IsVirtual, FnVirtual, FnNonVirtual); 350 351 // In the virtual path, the adjustment left 'This' pointing to the 352 // vtable of the correct base subobject. The "function pointer" is an 353 // offset within the vtable (+1 for the virtual flag on non-ARM). 354 CGF.EmitBlock(FnVirtual); 355 356 // Cast the adjusted this to a pointer to vtable pointer and load. 357 llvm::Type *VTableTy = Builder.getInt8PtrTy(); 358 llvm::Value *VTable = Builder.CreateBitCast(This, VTableTy->getPointerTo()); 359 VTable = Builder.CreateLoad(VTable, "memptr.vtable"); 360 361 // Apply the offset. 362 llvm::Value *VTableOffset = FnAsInt; 363 if (!UseARMMethodPtrABI) 364 VTableOffset = Builder.CreateSub(VTableOffset, ptrdiff_1); 365 VTable = Builder.CreateGEP(VTable, VTableOffset); 366 367 // Load the virtual function to call. 368 VTable = Builder.CreateBitCast(VTable, FTy->getPointerTo()->getPointerTo()); 369 llvm::Value *VirtualFn = Builder.CreateLoad(VTable, "memptr.virtualfn"); 370 CGF.EmitBranch(FnEnd); 371 372 // In the non-virtual path, the function pointer is actually a 373 // function pointer. 374 CGF.EmitBlock(FnNonVirtual); 375 llvm::Value *NonVirtualFn = 376 Builder.CreateIntToPtr(FnAsInt, FTy->getPointerTo(), "memptr.nonvirtualfn"); 377 378 // We're done. 379 CGF.EmitBlock(FnEnd); 380 llvm::PHINode *Callee = Builder.CreatePHI(FTy->getPointerTo(), 2); 381 Callee->addIncoming(VirtualFn, FnVirtual); 382 Callee->addIncoming(NonVirtualFn, FnNonVirtual); 383 return Callee; 384} 385 386/// Compute an l-value by applying the given pointer-to-member to a 387/// base object. 388llvm::Value *ItaniumCXXABI::EmitMemberDataPointerAddress(CodeGenFunction &CGF, 389 llvm::Value *Base, 390 llvm::Value *MemPtr, 391 const MemberPointerType *MPT) { 392 assert(MemPtr->getType() == CGM.PtrDiffTy); 393 394 CGBuilderTy &Builder = CGF.Builder; 395 396 unsigned AS = Base->getType()->getPointerAddressSpace(); 397 398 // Cast to char*. 399 Base = Builder.CreateBitCast(Base, Builder.getInt8Ty()->getPointerTo(AS)); 400 401 // Apply the offset, which we assume is non-null. 402 llvm::Value *Addr = Builder.CreateInBoundsGEP(Base, MemPtr, "memptr.offset"); 403 404 // Cast the address to the appropriate pointer type, adopting the 405 // address space of the base pointer. 406 llvm::Type *PType 407 = CGF.ConvertTypeForMem(MPT->getPointeeType())->getPointerTo(AS); 408 return Builder.CreateBitCast(Addr, PType); 409} 410 411/// Perform a bitcast, derived-to-base, or base-to-derived member pointer 412/// conversion. 413/// 414/// Bitcast conversions are always a no-op under Itanium. 415/// 416/// Obligatory offset/adjustment diagram: 417/// <-- offset --> <-- adjustment --> 418/// |--------------------------|----------------------|--------------------| 419/// ^Derived address point ^Base address point ^Member address point 420/// 421/// So when converting a base member pointer to a derived member pointer, 422/// we add the offset to the adjustment because the address point has 423/// decreased; and conversely, when converting a derived MP to a base MP 424/// we subtract the offset from the adjustment because the address point 425/// has increased. 426/// 427/// The standard forbids (at compile time) conversion to and from 428/// virtual bases, which is why we don't have to consider them here. 429/// 430/// The standard forbids (at run time) casting a derived MP to a base 431/// MP when the derived MP does not point to a member of the base. 432/// This is why -1 is a reasonable choice for null data member 433/// pointers. 434llvm::Value * 435ItaniumCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF, 436 const CastExpr *E, 437 llvm::Value *src) { 438 assert(E->getCastKind() == CK_DerivedToBaseMemberPointer || 439 E->getCastKind() == CK_BaseToDerivedMemberPointer || 440 E->getCastKind() == CK_ReinterpretMemberPointer); 441 442 // Under Itanium, reinterprets don't require any additional processing. 443 if (E->getCastKind() == CK_ReinterpretMemberPointer) return src; 444 445 // Use constant emission if we can. 446 if (isa<llvm::Constant>(src)) 447 return EmitMemberPointerConversion(E, cast<llvm::Constant>(src)); 448 449 llvm::Constant *adj = getMemberPointerAdjustment(E); 450 if (!adj) return src; 451 452 CGBuilderTy &Builder = CGF.Builder; 453 bool isDerivedToBase = (E->getCastKind() == CK_DerivedToBaseMemberPointer); 454 455 const MemberPointerType *destTy = 456 E->getType()->castAs<MemberPointerType>(); 457 458 // For member data pointers, this is just a matter of adding the 459 // offset if the source is non-null. 460 if (destTy->isMemberDataPointer()) { 461 llvm::Value *dst; 462 if (isDerivedToBase) 463 dst = Builder.CreateNSWSub(src, adj, "adj"); 464 else 465 dst = Builder.CreateNSWAdd(src, adj, "adj"); 466 467 // Null check. 468 llvm::Value *null = llvm::Constant::getAllOnesValue(src->getType()); 469 llvm::Value *isNull = Builder.CreateICmpEQ(src, null, "memptr.isnull"); 470 return Builder.CreateSelect(isNull, src, dst); 471 } 472 473 // The this-adjustment is left-shifted by 1 on ARM. 474 if (UseARMMethodPtrABI) { 475 uint64_t offset = cast<llvm::ConstantInt>(adj)->getZExtValue(); 476 offset <<= 1; 477 adj = llvm::ConstantInt::get(adj->getType(), offset); 478 } 479 480 llvm::Value *srcAdj = Builder.CreateExtractValue(src, 1, "src.adj"); 481 llvm::Value *dstAdj; 482 if (isDerivedToBase) 483 dstAdj = Builder.CreateNSWSub(srcAdj, adj, "adj"); 484 else 485 dstAdj = Builder.CreateNSWAdd(srcAdj, adj, "adj"); 486 487 return Builder.CreateInsertValue(src, dstAdj, 1); 488} 489 490llvm::Constant * 491ItaniumCXXABI::EmitMemberPointerConversion(const CastExpr *E, 492 llvm::Constant *src) { 493 assert(E->getCastKind() == CK_DerivedToBaseMemberPointer || 494 E->getCastKind() == CK_BaseToDerivedMemberPointer || 495 E->getCastKind() == CK_ReinterpretMemberPointer); 496 497 // Under Itanium, reinterprets don't require any additional processing. 498 if (E->getCastKind() == CK_ReinterpretMemberPointer) return src; 499 500 // If the adjustment is trivial, we don't need to do anything. 501 llvm::Constant *adj = getMemberPointerAdjustment(E); 502 if (!adj) return src; 503 504 bool isDerivedToBase = (E->getCastKind() == CK_DerivedToBaseMemberPointer); 505 506 const MemberPointerType *destTy = 507 E->getType()->castAs<MemberPointerType>(); 508 509 // For member data pointers, this is just a matter of adding the 510 // offset if the source is non-null. 511 if (destTy->isMemberDataPointer()) { 512 // null maps to null. 513 if (src->isAllOnesValue()) return src; 514 515 if (isDerivedToBase) 516 return llvm::ConstantExpr::getNSWSub(src, adj); 517 else 518 return llvm::ConstantExpr::getNSWAdd(src, adj); 519 } 520 521 // The this-adjustment is left-shifted by 1 on ARM. 522 if (UseARMMethodPtrABI) { 523 uint64_t offset = cast<llvm::ConstantInt>(adj)->getZExtValue(); 524 offset <<= 1; 525 adj = llvm::ConstantInt::get(adj->getType(), offset); 526 } 527 528 llvm::Constant *srcAdj = llvm::ConstantExpr::getExtractValue(src, 1); 529 llvm::Constant *dstAdj; 530 if (isDerivedToBase) 531 dstAdj = llvm::ConstantExpr::getNSWSub(srcAdj, adj); 532 else 533 dstAdj = llvm::ConstantExpr::getNSWAdd(srcAdj, adj); 534 535 return llvm::ConstantExpr::getInsertValue(src, dstAdj, 1); 536} 537 538llvm::Constant * 539ItaniumCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) { 540 // Itanium C++ ABI 2.3: 541 // A NULL pointer is represented as -1. 542 if (MPT->isMemberDataPointer()) 543 return llvm::ConstantInt::get(CGM.PtrDiffTy, -1ULL, /*isSigned=*/true); 544 545 llvm::Constant *Zero = llvm::ConstantInt::get(CGM.PtrDiffTy, 0); 546 llvm::Constant *Values[2] = { Zero, Zero }; 547 return llvm::ConstantStruct::getAnon(Values); 548} 549 550llvm::Constant * 551ItaniumCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT, 552 CharUnits offset) { 553 // Itanium C++ ABI 2.3: 554 // A pointer to data member is an offset from the base address of 555 // the class object containing it, represented as a ptrdiff_t 556 return llvm::ConstantInt::get(CGM.PtrDiffTy, offset.getQuantity()); 557} 558 559llvm::Constant *ItaniumCXXABI::EmitMemberPointer(const CXXMethodDecl *MD) { 560 return BuildMemberPointer(MD, CharUnits::Zero()); 561} 562 563llvm::Constant *ItaniumCXXABI::BuildMemberPointer(const CXXMethodDecl *MD, 564 CharUnits ThisAdjustment) { 565 assert(MD->isInstance() && "Member function must not be static!"); 566 MD = MD->getCanonicalDecl(); 567 568 CodeGenTypes &Types = CGM.getTypes(); 569 570 // Get the function pointer (or index if this is a virtual function). 571 llvm::Constant *MemPtr[2]; 572 if (MD->isVirtual()) { 573 uint64_t Index = CGM.getItaniumVTableContext().getMethodVTableIndex(MD); 574 575 const ASTContext &Context = getContext(); 576 CharUnits PointerWidth = 577 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0)); 578 uint64_t VTableOffset = (Index * PointerWidth.getQuantity()); 579 580 if (UseARMMethodPtrABI) { 581 // ARM C++ ABI 3.2.1: 582 // This ABI specifies that adj contains twice the this 583 // adjustment, plus 1 if the member function is virtual. The 584 // least significant bit of adj then makes exactly the same 585 // discrimination as the least significant bit of ptr does for 586 // Itanium. 587 MemPtr[0] = llvm::ConstantInt::get(CGM.PtrDiffTy, VTableOffset); 588 MemPtr[1] = llvm::ConstantInt::get(CGM.PtrDiffTy, 589 2 * ThisAdjustment.getQuantity() + 1); 590 } else { 591 // Itanium C++ ABI 2.3: 592 // For a virtual function, [the pointer field] is 1 plus the 593 // virtual table offset (in bytes) of the function, 594 // represented as a ptrdiff_t. 595 MemPtr[0] = llvm::ConstantInt::get(CGM.PtrDiffTy, VTableOffset + 1); 596 MemPtr[1] = llvm::ConstantInt::get(CGM.PtrDiffTy, 597 ThisAdjustment.getQuantity()); 598 } 599 } else { 600 const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>(); 601 llvm::Type *Ty; 602 // Check whether the function has a computable LLVM signature. 603 if (Types.isFuncTypeConvertible(FPT)) { 604 // The function has a computable LLVM signature; use the correct type. 605 Ty = Types.GetFunctionType(Types.arrangeCXXMethodDeclaration(MD)); 606 } else { 607 // Use an arbitrary non-function type to tell GetAddrOfFunction that the 608 // function type is incomplete. 609 Ty = CGM.PtrDiffTy; 610 } 611 llvm::Constant *addr = CGM.GetAddrOfFunction(MD, Ty); 612 613 MemPtr[0] = llvm::ConstantExpr::getPtrToInt(addr, CGM.PtrDiffTy); 614 MemPtr[1] = llvm::ConstantInt::get(CGM.PtrDiffTy, 615 (UseARMMethodPtrABI ? 2 : 1) * 616 ThisAdjustment.getQuantity()); 617 } 618 619 return llvm::ConstantStruct::getAnon(MemPtr); 620} 621 622llvm::Constant *ItaniumCXXABI::EmitMemberPointer(const APValue &MP, 623 QualType MPType) { 624 const MemberPointerType *MPT = MPType->castAs<MemberPointerType>(); 625 const ValueDecl *MPD = MP.getMemberPointerDecl(); 626 if (!MPD) 627 return EmitNullMemberPointer(MPT); 628 629 CharUnits ThisAdjustment = getMemberPointerPathAdjustment(MP); 630 631 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MPD)) 632 return BuildMemberPointer(MD, ThisAdjustment); 633 634 CharUnits FieldOffset = 635 getContext().toCharUnitsFromBits(getContext().getFieldOffset(MPD)); 636 return EmitMemberDataPointer(MPT, ThisAdjustment + FieldOffset); 637} 638 639/// The comparison algorithm is pretty easy: the member pointers are 640/// the same if they're either bitwise identical *or* both null. 641/// 642/// ARM is different here only because null-ness is more complicated. 643llvm::Value * 644ItaniumCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF, 645 llvm::Value *L, 646 llvm::Value *R, 647 const MemberPointerType *MPT, 648 bool Inequality) { 649 CGBuilderTy &Builder = CGF.Builder; 650 651 llvm::ICmpInst::Predicate Eq; 652 llvm::Instruction::BinaryOps And, Or; 653 if (Inequality) { 654 Eq = llvm::ICmpInst::ICMP_NE; 655 And = llvm::Instruction::Or; 656 Or = llvm::Instruction::And; 657 } else { 658 Eq = llvm::ICmpInst::ICMP_EQ; 659 And = llvm::Instruction::And; 660 Or = llvm::Instruction::Or; 661 } 662 663 // Member data pointers are easy because there's a unique null 664 // value, so it just comes down to bitwise equality. 665 if (MPT->isMemberDataPointer()) 666 return Builder.CreateICmp(Eq, L, R); 667 668 // For member function pointers, the tautologies are more complex. 669 // The Itanium tautology is: 670 // (L == R) <==> (L.ptr == R.ptr && (L.ptr == 0 || L.adj == R.adj)) 671 // The ARM tautology is: 672 // (L == R) <==> (L.ptr == R.ptr && 673 // (L.adj == R.adj || 674 // (L.ptr == 0 && ((L.adj|R.adj) & 1) == 0))) 675 // The inequality tautologies have exactly the same structure, except 676 // applying De Morgan's laws. 677 678 llvm::Value *LPtr = Builder.CreateExtractValue(L, 0, "lhs.memptr.ptr"); 679 llvm::Value *RPtr = Builder.CreateExtractValue(R, 0, "rhs.memptr.ptr"); 680 681 // This condition tests whether L.ptr == R.ptr. This must always be 682 // true for equality to hold. 683 llvm::Value *PtrEq = Builder.CreateICmp(Eq, LPtr, RPtr, "cmp.ptr"); 684 685 // This condition, together with the assumption that L.ptr == R.ptr, 686 // tests whether the pointers are both null. ARM imposes an extra 687 // condition. 688 llvm::Value *Zero = llvm::Constant::getNullValue(LPtr->getType()); 689 llvm::Value *EqZero = Builder.CreateICmp(Eq, LPtr, Zero, "cmp.ptr.null"); 690 691 // This condition tests whether L.adj == R.adj. If this isn't 692 // true, the pointers are unequal unless they're both null. 693 llvm::Value *LAdj = Builder.CreateExtractValue(L, 1, "lhs.memptr.adj"); 694 llvm::Value *RAdj = Builder.CreateExtractValue(R, 1, "rhs.memptr.adj"); 695 llvm::Value *AdjEq = Builder.CreateICmp(Eq, LAdj, RAdj, "cmp.adj"); 696 697 // Null member function pointers on ARM clear the low bit of Adj, 698 // so the zero condition has to check that neither low bit is set. 699 if (UseARMMethodPtrABI) { 700 llvm::Value *One = llvm::ConstantInt::get(LPtr->getType(), 1); 701 702 // Compute (l.adj | r.adj) & 1 and test it against zero. 703 llvm::Value *OrAdj = Builder.CreateOr(LAdj, RAdj, "or.adj"); 704 llvm::Value *OrAdjAnd1 = Builder.CreateAnd(OrAdj, One); 705 llvm::Value *OrAdjAnd1EqZero = Builder.CreateICmp(Eq, OrAdjAnd1, Zero, 706 "cmp.or.adj"); 707 EqZero = Builder.CreateBinOp(And, EqZero, OrAdjAnd1EqZero); 708 } 709 710 // Tie together all our conditions. 711 llvm::Value *Result = Builder.CreateBinOp(Or, EqZero, AdjEq); 712 Result = Builder.CreateBinOp(And, PtrEq, Result, 713 Inequality ? "memptr.ne" : "memptr.eq"); 714 return Result; 715} 716 717llvm::Value * 718ItaniumCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF, 719 llvm::Value *MemPtr, 720 const MemberPointerType *MPT) { 721 CGBuilderTy &Builder = CGF.Builder; 722 723 /// For member data pointers, this is just a check against -1. 724 if (MPT->isMemberDataPointer()) { 725 assert(MemPtr->getType() == CGM.PtrDiffTy); 726 llvm::Value *NegativeOne = 727 llvm::Constant::getAllOnesValue(MemPtr->getType()); 728 return Builder.CreateICmpNE(MemPtr, NegativeOne, "memptr.tobool"); 729 } 730 731 // In Itanium, a member function pointer is not null if 'ptr' is not null. 732 llvm::Value *Ptr = Builder.CreateExtractValue(MemPtr, 0, "memptr.ptr"); 733 734 llvm::Constant *Zero = llvm::ConstantInt::get(Ptr->getType(), 0); 735 llvm::Value *Result = Builder.CreateICmpNE(Ptr, Zero, "memptr.tobool"); 736 737 // On ARM, a member function pointer is also non-null if the low bit of 'adj' 738 // (the virtual bit) is set. 739 if (UseARMMethodPtrABI) { 740 llvm::Constant *One = llvm::ConstantInt::get(Ptr->getType(), 1); 741 llvm::Value *Adj = Builder.CreateExtractValue(MemPtr, 1, "memptr.adj"); 742 llvm::Value *VirtualBit = Builder.CreateAnd(Adj, One, "memptr.virtualbit"); 743 llvm::Value *IsVirtual = Builder.CreateICmpNE(VirtualBit, Zero, 744 "memptr.isvirtual"); 745 Result = Builder.CreateOr(Result, IsVirtual); 746 } 747 748 return Result; 749} 750 751/// The Itanium ABI requires non-zero initialization only for data 752/// member pointers, for which '0' is a valid offset. 753bool ItaniumCXXABI::isZeroInitializable(const MemberPointerType *MPT) { 754 return MPT->getPointeeType()->isFunctionType(); 755} 756 757/// The Itanium ABI always places an offset to the complete object 758/// at entry -2 in the vtable. 759llvm::Value *ItaniumCXXABI::adjustToCompleteObject(CodeGenFunction &CGF, 760 llvm::Value *ptr, 761 QualType type) { 762 // Grab the vtable pointer as an intptr_t*. 763 llvm::Value *vtable = CGF.GetVTablePtr(ptr, CGF.IntPtrTy->getPointerTo()); 764 765 // Track back to entry -2 and pull out the offset there. 766 llvm::Value *offsetPtr = 767 CGF.Builder.CreateConstInBoundsGEP1_64(vtable, -2, "complete-offset.ptr"); 768 llvm::LoadInst *offset = CGF.Builder.CreateLoad(offsetPtr); 769 offset->setAlignment(CGF.PointerAlignInBytes); 770 771 // Apply the offset. 772 ptr = CGF.Builder.CreateBitCast(ptr, CGF.Int8PtrTy); 773 return CGF.Builder.CreateInBoundsGEP(ptr, offset); 774} 775 776llvm::Value * 777ItaniumCXXABI::GetVirtualBaseClassOffset(CodeGenFunction &CGF, 778 llvm::Value *This, 779 const CXXRecordDecl *ClassDecl, 780 const CXXRecordDecl *BaseClassDecl) { 781 llvm::Value *VTablePtr = CGF.GetVTablePtr(This, CGM.Int8PtrTy); 782 CharUnits VBaseOffsetOffset = 783 CGM.getItaniumVTableContext().getVirtualBaseOffsetOffset(ClassDecl, 784 BaseClassDecl); 785 786 llvm::Value *VBaseOffsetPtr = 787 CGF.Builder.CreateConstGEP1_64(VTablePtr, VBaseOffsetOffset.getQuantity(), 788 "vbase.offset.ptr"); 789 VBaseOffsetPtr = CGF.Builder.CreateBitCast(VBaseOffsetPtr, 790 CGM.PtrDiffTy->getPointerTo()); 791 792 llvm::Value *VBaseOffset = 793 CGF.Builder.CreateLoad(VBaseOffsetPtr, "vbase.offset"); 794 795 return VBaseOffset; 796} 797 798/// The generic ABI passes 'this', plus a VTT if it's initializing a 799/// base subobject. 800void ItaniumCXXABI::BuildConstructorSignature(const CXXConstructorDecl *Ctor, 801 CXXCtorType Type, 802 CanQualType &ResTy, 803 SmallVectorImpl<CanQualType> &ArgTys) { 804 ASTContext &Context = getContext(); 805 806 // 'this' parameter is already there, as well as 'this' return if 807 // HasThisReturn(GlobalDecl(Ctor, Type)) is true 808 809 // Check if we need to add a VTT parameter (which has type void **). 810 if (Type == Ctor_Base && Ctor->getParent()->getNumVBases() != 0) 811 ArgTys.push_back(Context.getPointerType(Context.VoidPtrTy)); 812} 813 814void ItaniumCXXABI::EmitCXXConstructors(const CXXConstructorDecl *D) { 815 // Just make sure we're in sync with TargetCXXABI. 816 assert(CGM.getTarget().getCXXABI().hasConstructorVariants()); 817 818 // The constructor used for constructing this as a complete class; 819 // constucts the virtual bases, then calls the base constructor. 820 if (!D->getParent()->isAbstract()) { 821 // We don't need to emit the complete ctor if the class is abstract. 822 CGM.EmitGlobal(GlobalDecl(D, Ctor_Complete)); 823 } 824 825 // The constructor used for constructing this as a base class; 826 // ignores virtual bases. 827 CGM.EmitGlobal(GlobalDecl(D, Ctor_Base)); 828} 829 830/// The generic ABI passes 'this', plus a VTT if it's destroying a 831/// base subobject. 832void ItaniumCXXABI::BuildDestructorSignature(const CXXDestructorDecl *Dtor, 833 CXXDtorType Type, 834 CanQualType &ResTy, 835 SmallVectorImpl<CanQualType> &ArgTys) { 836 ASTContext &Context = getContext(); 837 838 // 'this' parameter is already there, as well as 'this' return if 839 // HasThisReturn(GlobalDecl(Dtor, Type)) is true 840 841 // Check if we need to add a VTT parameter (which has type void **). 842 if (Type == Dtor_Base && Dtor->getParent()->getNumVBases() != 0) 843 ArgTys.push_back(Context.getPointerType(Context.VoidPtrTy)); 844} 845 846void ItaniumCXXABI::EmitCXXDestructors(const CXXDestructorDecl *D) { 847 // The destructor in a virtual table is always a 'deleting' 848 // destructor, which calls the complete destructor and then uses the 849 // appropriate operator delete. 850 if (D->isVirtual()) 851 CGM.EmitGlobal(GlobalDecl(D, Dtor_Deleting)); 852 853 // The destructor used for destructing this as a most-derived class; 854 // call the base destructor and then destructs any virtual bases. 855 CGM.EmitGlobal(GlobalDecl(D, Dtor_Complete)); 856 857 // The destructor used for destructing this as a base class; ignores 858 // virtual bases. 859 CGM.EmitGlobal(GlobalDecl(D, Dtor_Base)); 860} 861 862void ItaniumCXXABI::BuildInstanceFunctionParams(CodeGenFunction &CGF, 863 QualType &ResTy, 864 FunctionArgList &Params) { 865 /// Create the 'this' variable. 866 BuildThisParam(CGF, Params); 867 868 const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl()); 869 assert(MD->isInstance()); 870 871 // Check if we need a VTT parameter as well. 872 if (NeedsVTTParameter(CGF.CurGD)) { 873 ASTContext &Context = getContext(); 874 875 // FIXME: avoid the fake decl 876 QualType T = Context.getPointerType(Context.VoidPtrTy); 877 ImplicitParamDecl *VTTDecl 878 = ImplicitParamDecl::Create(Context, 0, MD->getLocation(), 879 &Context.Idents.get("vtt"), T); 880 Params.push_back(VTTDecl); 881 getVTTDecl(CGF) = VTTDecl; 882 } 883} 884 885void ItaniumCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) { 886 /// Initialize the 'this' slot. 887 EmitThisParam(CGF); 888 889 /// Initialize the 'vtt' slot if needed. 890 if (getVTTDecl(CGF)) { 891 getVTTValue(CGF) 892 = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(getVTTDecl(CGF)), 893 "vtt"); 894 } 895 896 /// If this is a function that the ABI specifies returns 'this', initialize 897 /// the return slot to 'this' at the start of the function. 898 /// 899 /// Unlike the setting of return types, this is done within the ABI 900 /// implementation instead of by clients of CGCXXABI because: 901 /// 1) getThisValue is currently protected 902 /// 2) in theory, an ABI could implement 'this' returns some other way; 903 /// HasThisReturn only specifies a contract, not the implementation 904 if (HasThisReturn(CGF.CurGD)) 905 CGF.Builder.CreateStore(getThisValue(CGF), CGF.ReturnValue); 906} 907 908void ItaniumCXXABI::EmitConstructorCall(CodeGenFunction &CGF, 909 const CXXConstructorDecl *D, 910 CXXCtorType Type, 911 bool ForVirtualBase, bool Delegating, 912 llvm::Value *This, 913 CallExpr::const_arg_iterator ArgBeg, 914 CallExpr::const_arg_iterator ArgEnd) { 915 llvm::Value *VTT = CGF.GetVTTParameter(GlobalDecl(D, Type), ForVirtualBase, 916 Delegating); 917 QualType VTTTy = getContext().getPointerType(getContext().VoidPtrTy); 918 llvm::Value *Callee = CGM.GetAddrOfCXXConstructor(D, Type); 919 920 // FIXME: Provide a source location here. 921 CGF.EmitCXXMemberCall(D, SourceLocation(), Callee, ReturnValueSlot(), 922 This, VTT, VTTTy, ArgBeg, ArgEnd); 923} 924 925void ItaniumCXXABI::emitVTableDefinitions(CodeGenVTables &CGVT, 926 const CXXRecordDecl *RD) { 927 llvm::GlobalVariable *VTable = getAddrOfVTable(RD, CharUnits()); 928 if (VTable->hasInitializer()) 929 return; 930 931 ItaniumVTableContext &VTContext = CGM.getItaniumVTableContext(); 932 const VTableLayout &VTLayout = VTContext.getVTableLayout(RD); 933 llvm::GlobalVariable::LinkageTypes Linkage = CGM.getVTableLinkage(RD); 934 935 // Create and set the initializer. 936 llvm::Constant *Init = CGVT.CreateVTableInitializer( 937 RD, VTLayout.vtable_component_begin(), VTLayout.getNumVTableComponents(), 938 VTLayout.vtable_thunk_begin(), VTLayout.getNumVTableThunks()); 939 VTable->setInitializer(Init); 940 941 // Set the correct linkage. 942 VTable->setLinkage(Linkage); 943 944 // Set the right visibility. 945 CGM.setTypeVisibility(VTable, RD, CodeGenModule::TVK_ForVTable); 946 947 // If this is the magic class __cxxabiv1::__fundamental_type_info, 948 // we will emit the typeinfo for the fundamental types. This is the 949 // same behaviour as GCC. 950 const DeclContext *DC = RD->getDeclContext(); 951 if (RD->getIdentifier() && 952 RD->getIdentifier()->isStr("__fundamental_type_info") && 953 isa<NamespaceDecl>(DC) && cast<NamespaceDecl>(DC)->getIdentifier() && 954 cast<NamespaceDecl>(DC)->getIdentifier()->isStr("__cxxabiv1") && 955 DC->getParent()->isTranslationUnit()) 956 CGM.EmitFundamentalRTTIDescriptors(); 957} 958 959llvm::Value *ItaniumCXXABI::getVTableAddressPointInStructor( 960 CodeGenFunction &CGF, const CXXRecordDecl *VTableClass, BaseSubobject Base, 961 const CXXRecordDecl *NearestVBase, bool &NeedsVirtualOffset) { 962 bool NeedsVTTParam = CGM.getCXXABI().NeedsVTTParameter(CGF.CurGD); 963 NeedsVirtualOffset = (NeedsVTTParam && NearestVBase); 964 965 llvm::Value *VTableAddressPoint; 966 if (NeedsVTTParam && (Base.getBase()->getNumVBases() || NearestVBase)) { 967 // Get the secondary vpointer index. 968 uint64_t VirtualPointerIndex = 969 CGM.getVTables().getSecondaryVirtualPointerIndex(VTableClass, Base); 970 971 /// Load the VTT. 972 llvm::Value *VTT = CGF.LoadCXXVTT(); 973 if (VirtualPointerIndex) 974 VTT = CGF.Builder.CreateConstInBoundsGEP1_64(VTT, VirtualPointerIndex); 975 976 // And load the address point from the VTT. 977 VTableAddressPoint = CGF.Builder.CreateLoad(VTT); 978 } else { 979 llvm::Constant *VTable = 980 CGM.getCXXABI().getAddrOfVTable(VTableClass, CharUnits()); 981 uint64_t AddressPoint = CGM.getItaniumVTableContext() 982 .getVTableLayout(VTableClass) 983 .getAddressPoint(Base); 984 VTableAddressPoint = 985 CGF.Builder.CreateConstInBoundsGEP2_64(VTable, 0, AddressPoint); 986 } 987 988 return VTableAddressPoint; 989} 990 991llvm::Constant *ItaniumCXXABI::getVTableAddressPointForConstExpr( 992 BaseSubobject Base, const CXXRecordDecl *VTableClass) { 993 llvm::Constant *VTable = getAddrOfVTable(VTableClass, CharUnits()); 994 995 // Find the appropriate vtable within the vtable group. 996 uint64_t AddressPoint = CGM.getItaniumVTableContext() 997 .getVTableLayout(VTableClass) 998 .getAddressPoint(Base); 999 llvm::Value *Indices[] = { 1000 llvm::ConstantInt::get(CGM.Int64Ty, 0), 1001 llvm::ConstantInt::get(CGM.Int64Ty, AddressPoint) 1002 }; 1003 1004 return llvm::ConstantExpr::getInBoundsGetElementPtr(VTable, Indices); 1005} 1006 1007llvm::GlobalVariable *ItaniumCXXABI::getAddrOfVTable(const CXXRecordDecl *RD, 1008 CharUnits VPtrOffset) { 1009 assert(VPtrOffset.isZero() && "Itanium ABI only supports zero vptr offsets"); 1010 1011 llvm::GlobalVariable *&VTable = VTables[RD]; 1012 if (VTable) 1013 return VTable; 1014 1015 // Queue up this v-table for possible deferred emission. 1016 CGM.addDeferredVTable(RD); 1017 1018 SmallString<256> OutName; 1019 llvm::raw_svector_ostream Out(OutName); 1020 getMangleContext().mangleCXXVTable(RD, Out); 1021 Out.flush(); 1022 StringRef Name = OutName.str(); 1023 1024 ItaniumVTableContext &VTContext = CGM.getItaniumVTableContext(); 1025 llvm::ArrayType *ArrayType = llvm::ArrayType::get( 1026 CGM.Int8PtrTy, VTContext.getVTableLayout(RD).getNumVTableComponents()); 1027 1028 VTable = CGM.CreateOrReplaceCXXRuntimeVariable( 1029 Name, ArrayType, llvm::GlobalValue::ExternalLinkage); 1030 VTable->setUnnamedAddr(true); 1031 return VTable; 1032} 1033 1034llvm::Value *ItaniumCXXABI::getVirtualFunctionPointer(CodeGenFunction &CGF, 1035 GlobalDecl GD, 1036 llvm::Value *This, 1037 llvm::Type *Ty) { 1038 GD = GD.getCanonicalDecl(); 1039 Ty = Ty->getPointerTo()->getPointerTo(); 1040 llvm::Value *VTable = CGF.GetVTablePtr(This, Ty); 1041 1042 uint64_t VTableIndex = CGM.getItaniumVTableContext().getMethodVTableIndex(GD); 1043 llvm::Value *VFuncPtr = 1044 CGF.Builder.CreateConstInBoundsGEP1_64(VTable, VTableIndex, "vfn"); 1045 return CGF.Builder.CreateLoad(VFuncPtr); 1046} 1047 1048void ItaniumCXXABI::EmitVirtualDestructorCall(CodeGenFunction &CGF, 1049 const CXXDestructorDecl *Dtor, 1050 CXXDtorType DtorType, 1051 SourceLocation CallLoc, 1052 llvm::Value *This) { 1053 assert(DtorType == Dtor_Deleting || DtorType == Dtor_Complete); 1054 1055 const CGFunctionInfo *FInfo 1056 = &CGM.getTypes().arrangeCXXDestructor(Dtor, DtorType); 1057 llvm::Type *Ty = CGF.CGM.getTypes().GetFunctionType(*FInfo); 1058 llvm::Value *Callee = 1059 getVirtualFunctionPointer(CGF, GlobalDecl(Dtor, DtorType), This, Ty); 1060 1061 CGF.EmitCXXMemberCall(Dtor, CallLoc, Callee, ReturnValueSlot(), This, 1062 /*ImplicitParam=*/0, QualType(), 0, 0); 1063} 1064 1065void ItaniumCXXABI::emitVirtualInheritanceTables(const CXXRecordDecl *RD) { 1066 CodeGenVTables &VTables = CGM.getVTables(); 1067 llvm::GlobalVariable *VTT = VTables.GetAddrOfVTT(RD); 1068 VTables.EmitVTTDefinition(VTT, CGM.getVTableLinkage(RD), RD); 1069} 1070 1071static llvm::Value *performTypeAdjustment(CodeGenFunction &CGF, 1072 llvm::Value *Ptr, 1073 int64_t NonVirtualAdjustment, 1074 int64_t VirtualAdjustment, 1075 bool IsReturnAdjustment) { 1076 if (!NonVirtualAdjustment && !VirtualAdjustment) 1077 return Ptr; 1078 1079 llvm::Type *Int8PtrTy = CGF.Int8PtrTy; 1080 llvm::Value *V = CGF.Builder.CreateBitCast(Ptr, Int8PtrTy); 1081 1082 if (NonVirtualAdjustment && !IsReturnAdjustment) { 1083 // Perform the non-virtual adjustment for a base-to-derived cast. 1084 V = CGF.Builder.CreateConstInBoundsGEP1_64(V, NonVirtualAdjustment); 1085 } 1086 1087 if (VirtualAdjustment) { 1088 llvm::Type *PtrDiffTy = 1089 CGF.ConvertType(CGF.getContext().getPointerDiffType()); 1090 1091 // Perform the virtual adjustment. 1092 llvm::Value *VTablePtrPtr = 1093 CGF.Builder.CreateBitCast(V, Int8PtrTy->getPointerTo()); 1094 1095 llvm::Value *VTablePtr = CGF.Builder.CreateLoad(VTablePtrPtr); 1096 1097 llvm::Value *OffsetPtr = 1098 CGF.Builder.CreateConstInBoundsGEP1_64(VTablePtr, VirtualAdjustment); 1099 1100 OffsetPtr = CGF.Builder.CreateBitCast(OffsetPtr, PtrDiffTy->getPointerTo()); 1101 1102 // Load the adjustment offset from the vtable. 1103 llvm::Value *Offset = CGF.Builder.CreateLoad(OffsetPtr); 1104 1105 // Adjust our pointer. 1106 V = CGF.Builder.CreateInBoundsGEP(V, Offset); 1107 } 1108 1109 if (NonVirtualAdjustment && IsReturnAdjustment) { 1110 // Perform the non-virtual adjustment for a derived-to-base cast. 1111 V = CGF.Builder.CreateConstInBoundsGEP1_64(V, NonVirtualAdjustment); 1112 } 1113 1114 // Cast back to the original type. 1115 return CGF.Builder.CreateBitCast(V, Ptr->getType()); 1116} 1117 1118llvm::Value *ItaniumCXXABI::performThisAdjustment(CodeGenFunction &CGF, 1119 llvm::Value *This, 1120 const ThisAdjustment &TA) { 1121 return performTypeAdjustment(CGF, This, TA.NonVirtual, 1122 TA.Virtual.Itanium.VCallOffsetOffset, 1123 /*IsReturnAdjustment=*/false); 1124} 1125 1126llvm::Value * 1127ItaniumCXXABI::performReturnAdjustment(CodeGenFunction &CGF, llvm::Value *Ret, 1128 const ReturnAdjustment &RA) { 1129 return performTypeAdjustment(CGF, Ret, RA.NonVirtual, 1130 RA.Virtual.Itanium.VBaseOffsetOffset, 1131 /*IsReturnAdjustment=*/true); 1132} 1133 1134void ARMCXXABI::EmitReturnFromThunk(CodeGenFunction &CGF, 1135 RValue RV, QualType ResultType) { 1136 if (!isa<CXXDestructorDecl>(CGF.CurGD.getDecl())) 1137 return ItaniumCXXABI::EmitReturnFromThunk(CGF, RV, ResultType); 1138 1139 // Destructor thunks in the ARM ABI have indeterminate results. 1140 llvm::Type *T = 1141 cast<llvm::PointerType>(CGF.ReturnValue->getType())->getElementType(); 1142 RValue Undef = RValue::get(llvm::UndefValue::get(T)); 1143 return ItaniumCXXABI::EmitReturnFromThunk(CGF, Undef, ResultType); 1144} 1145 1146/************************** Array allocation cookies **************************/ 1147 1148CharUnits ItaniumCXXABI::getArrayCookieSizeImpl(QualType elementType) { 1149 // The array cookie is a size_t; pad that up to the element alignment. 1150 // The cookie is actually right-justified in that space. 1151 return std::max(CharUnits::fromQuantity(CGM.SizeSizeInBytes), 1152 CGM.getContext().getTypeAlignInChars(elementType)); 1153} 1154 1155llvm::Value *ItaniumCXXABI::InitializeArrayCookie(CodeGenFunction &CGF, 1156 llvm::Value *NewPtr, 1157 llvm::Value *NumElements, 1158 const CXXNewExpr *expr, 1159 QualType ElementType) { 1160 assert(requiresArrayCookie(expr)); 1161 1162 unsigned AS = NewPtr->getType()->getPointerAddressSpace(); 1163 1164 ASTContext &Ctx = getContext(); 1165 QualType SizeTy = Ctx.getSizeType(); 1166 CharUnits SizeSize = Ctx.getTypeSizeInChars(SizeTy); 1167 1168 // The size of the cookie. 1169 CharUnits CookieSize = 1170 std::max(SizeSize, Ctx.getTypeAlignInChars(ElementType)); 1171 assert(CookieSize == getArrayCookieSizeImpl(ElementType)); 1172 1173 // Compute an offset to the cookie. 1174 llvm::Value *CookiePtr = NewPtr; 1175 CharUnits CookieOffset = CookieSize - SizeSize; 1176 if (!CookieOffset.isZero()) 1177 CookiePtr = CGF.Builder.CreateConstInBoundsGEP1_64(CookiePtr, 1178 CookieOffset.getQuantity()); 1179 1180 // Write the number of elements into the appropriate slot. 1181 llvm::Value *NumElementsPtr 1182 = CGF.Builder.CreateBitCast(CookiePtr, 1183 CGF.ConvertType(SizeTy)->getPointerTo(AS)); 1184 CGF.Builder.CreateStore(NumElements, NumElementsPtr); 1185 1186 // Finally, compute a pointer to the actual data buffer by skipping 1187 // over the cookie completely. 1188 return CGF.Builder.CreateConstInBoundsGEP1_64(NewPtr, 1189 CookieSize.getQuantity()); 1190} 1191 1192llvm::Value *ItaniumCXXABI::readArrayCookieImpl(CodeGenFunction &CGF, 1193 llvm::Value *allocPtr, 1194 CharUnits cookieSize) { 1195 // The element size is right-justified in the cookie. 1196 llvm::Value *numElementsPtr = allocPtr; 1197 CharUnits numElementsOffset = 1198 cookieSize - CharUnits::fromQuantity(CGF.SizeSizeInBytes); 1199 if (!numElementsOffset.isZero()) 1200 numElementsPtr = 1201 CGF.Builder.CreateConstInBoundsGEP1_64(numElementsPtr, 1202 numElementsOffset.getQuantity()); 1203 1204 unsigned AS = allocPtr->getType()->getPointerAddressSpace(); 1205 numElementsPtr = 1206 CGF.Builder.CreateBitCast(numElementsPtr, CGF.SizeTy->getPointerTo(AS)); 1207 return CGF.Builder.CreateLoad(numElementsPtr); 1208} 1209 1210CharUnits ARMCXXABI::getArrayCookieSizeImpl(QualType elementType) { 1211 // ARM says that the cookie is always: 1212 // struct array_cookie { 1213 // std::size_t element_size; // element_size != 0 1214 // std::size_t element_count; 1215 // }; 1216 // But the base ABI doesn't give anything an alignment greater than 1217 // 8, so we can dismiss this as typical ABI-author blindness to 1218 // actual language complexity and round up to the element alignment. 1219 return std::max(CharUnits::fromQuantity(2 * CGM.SizeSizeInBytes), 1220 CGM.getContext().getTypeAlignInChars(elementType)); 1221} 1222 1223llvm::Value *ARMCXXABI::InitializeArrayCookie(CodeGenFunction &CGF, 1224 llvm::Value *newPtr, 1225 llvm::Value *numElements, 1226 const CXXNewExpr *expr, 1227 QualType elementType) { 1228 assert(requiresArrayCookie(expr)); 1229 1230 // NewPtr is a char*, but we generalize to arbitrary addrspaces. 1231 unsigned AS = newPtr->getType()->getPointerAddressSpace(); 1232 1233 // The cookie is always at the start of the buffer. 1234 llvm::Value *cookie = newPtr; 1235 1236 // The first element is the element size. 1237 cookie = CGF.Builder.CreateBitCast(cookie, CGF.SizeTy->getPointerTo(AS)); 1238 llvm::Value *elementSize = llvm::ConstantInt::get(CGF.SizeTy, 1239 getContext().getTypeSizeInChars(elementType).getQuantity()); 1240 CGF.Builder.CreateStore(elementSize, cookie); 1241 1242 // The second element is the element count. 1243 cookie = CGF.Builder.CreateConstInBoundsGEP1_32(cookie, 1); 1244 CGF.Builder.CreateStore(numElements, cookie); 1245 1246 // Finally, compute a pointer to the actual data buffer by skipping 1247 // over the cookie completely. 1248 CharUnits cookieSize = ARMCXXABI::getArrayCookieSizeImpl(elementType); 1249 return CGF.Builder.CreateConstInBoundsGEP1_64(newPtr, 1250 cookieSize.getQuantity()); 1251} 1252 1253llvm::Value *ARMCXXABI::readArrayCookieImpl(CodeGenFunction &CGF, 1254 llvm::Value *allocPtr, 1255 CharUnits cookieSize) { 1256 // The number of elements is at offset sizeof(size_t) relative to 1257 // the allocated pointer. 1258 llvm::Value *numElementsPtr 1259 = CGF.Builder.CreateConstInBoundsGEP1_64(allocPtr, CGF.SizeSizeInBytes); 1260 1261 unsigned AS = allocPtr->getType()->getPointerAddressSpace(); 1262 numElementsPtr = 1263 CGF.Builder.CreateBitCast(numElementsPtr, CGF.SizeTy->getPointerTo(AS)); 1264 return CGF.Builder.CreateLoad(numElementsPtr); 1265} 1266 1267/*********************** Static local initialization **************************/ 1268 1269static llvm::Constant *getGuardAcquireFn(CodeGenModule &CGM, 1270 llvm::PointerType *GuardPtrTy) { 1271 // int __cxa_guard_acquire(__guard *guard_object); 1272 llvm::FunctionType *FTy = 1273 llvm::FunctionType::get(CGM.getTypes().ConvertType(CGM.getContext().IntTy), 1274 GuardPtrTy, /*isVarArg=*/false); 1275 return CGM.CreateRuntimeFunction(FTy, "__cxa_guard_acquire", 1276 llvm::AttributeSet::get(CGM.getLLVMContext(), 1277 llvm::AttributeSet::FunctionIndex, 1278 llvm::Attribute::NoUnwind)); 1279} 1280 1281static llvm::Constant *getGuardReleaseFn(CodeGenModule &CGM, 1282 llvm::PointerType *GuardPtrTy) { 1283 // void __cxa_guard_release(__guard *guard_object); 1284 llvm::FunctionType *FTy = 1285 llvm::FunctionType::get(CGM.VoidTy, GuardPtrTy, /*isVarArg=*/false); 1286 return CGM.CreateRuntimeFunction(FTy, "__cxa_guard_release", 1287 llvm::AttributeSet::get(CGM.getLLVMContext(), 1288 llvm::AttributeSet::FunctionIndex, 1289 llvm::Attribute::NoUnwind)); 1290} 1291 1292static llvm::Constant *getGuardAbortFn(CodeGenModule &CGM, 1293 llvm::PointerType *GuardPtrTy) { 1294 // void __cxa_guard_abort(__guard *guard_object); 1295 llvm::FunctionType *FTy = 1296 llvm::FunctionType::get(CGM.VoidTy, GuardPtrTy, /*isVarArg=*/false); 1297 return CGM.CreateRuntimeFunction(FTy, "__cxa_guard_abort", 1298 llvm::AttributeSet::get(CGM.getLLVMContext(), 1299 llvm::AttributeSet::FunctionIndex, 1300 llvm::Attribute::NoUnwind)); 1301} 1302 1303namespace { 1304 struct CallGuardAbort : EHScopeStack::Cleanup { 1305 llvm::GlobalVariable *Guard; 1306 CallGuardAbort(llvm::GlobalVariable *Guard) : Guard(Guard) {} 1307 1308 void Emit(CodeGenFunction &CGF, Flags flags) { 1309 CGF.EmitNounwindRuntimeCall(getGuardAbortFn(CGF.CGM, Guard->getType()), 1310 Guard); 1311 } 1312 }; 1313} 1314 1315/// The ARM code here follows the Itanium code closely enough that we 1316/// just special-case it at particular places. 1317void ItaniumCXXABI::EmitGuardedInit(CodeGenFunction &CGF, 1318 const VarDecl &D, 1319 llvm::GlobalVariable *var, 1320 bool shouldPerformInit) { 1321 CGBuilderTy &Builder = CGF.Builder; 1322 1323 // We only need to use thread-safe statics for local non-TLS variables; 1324 // global initialization is always single-threaded. 1325 bool threadsafe = getContext().getLangOpts().ThreadsafeStatics && 1326 D.isLocalVarDecl() && !D.getTLSKind(); 1327 1328 // If we have a global variable with internal linkage and thread-safe statics 1329 // are disabled, we can just let the guard variable be of type i8. 1330 bool useInt8GuardVariable = !threadsafe && var->hasInternalLinkage(); 1331 1332 llvm::IntegerType *guardTy; 1333 if (useInt8GuardVariable) { 1334 guardTy = CGF.Int8Ty; 1335 } else { 1336 // Guard variables are 64 bits in the generic ABI and size width on ARM 1337 // (i.e. 32-bit on AArch32, 64-bit on AArch64). 1338 guardTy = (UseARMGuardVarABI ? CGF.SizeTy : CGF.Int64Ty); 1339 } 1340 llvm::PointerType *guardPtrTy = guardTy->getPointerTo(); 1341 1342 // Create the guard variable if we don't already have it (as we 1343 // might if we're double-emitting this function body). 1344 llvm::GlobalVariable *guard = CGM.getStaticLocalDeclGuardAddress(&D); 1345 if (!guard) { 1346 // Mangle the name for the guard. 1347 SmallString<256> guardName; 1348 { 1349 llvm::raw_svector_ostream out(guardName); 1350 getMangleContext().mangleStaticGuardVariable(&D, out); 1351 out.flush(); 1352 } 1353 1354 // Create the guard variable with a zero-initializer. 1355 // Just absorb linkage and visibility from the guarded variable. 1356 guard = new llvm::GlobalVariable(CGM.getModule(), guardTy, 1357 false, var->getLinkage(), 1358 llvm::ConstantInt::get(guardTy, 0), 1359 guardName.str()); 1360 guard->setVisibility(var->getVisibility()); 1361 // If the variable is thread-local, so is its guard variable. 1362 guard->setThreadLocalMode(var->getThreadLocalMode()); 1363 1364 CGM.setStaticLocalDeclGuardAddress(&D, guard); 1365 } 1366 1367 // Test whether the variable has completed initialization. 1368 llvm::Value *isInitialized; 1369 1370 // ARM C++ ABI 3.2.3.1: 1371 // To support the potential use of initialization guard variables 1372 // as semaphores that are the target of ARM SWP and LDREX/STREX 1373 // synchronizing instructions we define a static initialization 1374 // guard variable to be a 4-byte aligned, 4- byte word with the 1375 // following inline access protocol. 1376 // #define INITIALIZED 1 1377 // if ((obj_guard & INITIALIZED) != INITIALIZED) { 1378 // if (__cxa_guard_acquire(&obj_guard)) 1379 // ... 1380 // } 1381 if (UseARMGuardVarABI && !useInt8GuardVariable) { 1382 llvm::Value *V = Builder.CreateLoad(guard); 1383 llvm::Value *Test1 = llvm::ConstantInt::get(guardTy, 1); 1384 V = Builder.CreateAnd(V, Test1); 1385 isInitialized = Builder.CreateIsNull(V, "guard.uninitialized"); 1386 1387 // Itanium C++ ABI 3.3.2: 1388 // The following is pseudo-code showing how these functions can be used: 1389 // if (obj_guard.first_byte == 0) { 1390 // if ( __cxa_guard_acquire (&obj_guard) ) { 1391 // try { 1392 // ... initialize the object ...; 1393 // } catch (...) { 1394 // __cxa_guard_abort (&obj_guard); 1395 // throw; 1396 // } 1397 // ... queue object destructor with __cxa_atexit() ...; 1398 // __cxa_guard_release (&obj_guard); 1399 // } 1400 // } 1401 } else { 1402 // Load the first byte of the guard variable. 1403 llvm::LoadInst *LI = 1404 Builder.CreateLoad(Builder.CreateBitCast(guard, CGM.Int8PtrTy)); 1405 LI->setAlignment(1); 1406 1407 // Itanium ABI: 1408 // An implementation supporting thread-safety on multiprocessor 1409 // systems must also guarantee that references to the initialized 1410 // object do not occur before the load of the initialization flag. 1411 // 1412 // In LLVM, we do this by marking the load Acquire. 1413 if (threadsafe) 1414 LI->setAtomic(llvm::Acquire); 1415 1416 isInitialized = Builder.CreateIsNull(LI, "guard.uninitialized"); 1417 } 1418 1419 llvm::BasicBlock *InitCheckBlock = CGF.createBasicBlock("init.check"); 1420 llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end"); 1421 1422 // Check if the first byte of the guard variable is zero. 1423 Builder.CreateCondBr(isInitialized, InitCheckBlock, EndBlock); 1424 1425 CGF.EmitBlock(InitCheckBlock); 1426 1427 // Variables used when coping with thread-safe statics and exceptions. 1428 if (threadsafe) { 1429 // Call __cxa_guard_acquire. 1430 llvm::Value *V 1431 = CGF.EmitNounwindRuntimeCall(getGuardAcquireFn(CGM, guardPtrTy), guard); 1432 1433 llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init"); 1434 1435 Builder.CreateCondBr(Builder.CreateIsNotNull(V, "tobool"), 1436 InitBlock, EndBlock); 1437 1438 // Call __cxa_guard_abort along the exceptional edge. 1439 CGF.EHStack.pushCleanup<CallGuardAbort>(EHCleanup, guard); 1440 1441 CGF.EmitBlock(InitBlock); 1442 } 1443 1444 // Emit the initializer and add a global destructor if appropriate. 1445 CGF.EmitCXXGlobalVarDeclInit(D, var, shouldPerformInit); 1446 1447 if (threadsafe) { 1448 // Pop the guard-abort cleanup if we pushed one. 1449 CGF.PopCleanupBlock(); 1450 1451 // Call __cxa_guard_release. This cannot throw. 1452 CGF.EmitNounwindRuntimeCall(getGuardReleaseFn(CGM, guardPtrTy), guard); 1453 } else { 1454 Builder.CreateStore(llvm::ConstantInt::get(guardTy, 1), guard); 1455 } 1456 1457 CGF.EmitBlock(EndBlock); 1458} 1459 1460/// Register a global destructor using __cxa_atexit. 1461static void emitGlobalDtorWithCXAAtExit(CodeGenFunction &CGF, 1462 llvm::Constant *dtor, 1463 llvm::Constant *addr, 1464 bool TLS) { 1465 const char *Name = "__cxa_atexit"; 1466 if (TLS) { 1467 const llvm::Triple &T = CGF.getTarget().getTriple(); 1468 Name = T.isMacOSX() ? "_tlv_atexit" : "__cxa_thread_atexit"; 1469 } 1470 1471 // We're assuming that the destructor function is something we can 1472 // reasonably call with the default CC. Go ahead and cast it to the 1473 // right prototype. 1474 llvm::Type *dtorTy = 1475 llvm::FunctionType::get(CGF.VoidTy, CGF.Int8PtrTy, false)->getPointerTo(); 1476 1477 // extern "C" int __cxa_atexit(void (*f)(void *), void *p, void *d); 1478 llvm::Type *paramTys[] = { dtorTy, CGF.Int8PtrTy, CGF.Int8PtrTy }; 1479 llvm::FunctionType *atexitTy = 1480 llvm::FunctionType::get(CGF.IntTy, paramTys, false); 1481 1482 // Fetch the actual function. 1483 llvm::Constant *atexit = CGF.CGM.CreateRuntimeFunction(atexitTy, Name); 1484 if (llvm::Function *fn = dyn_cast<llvm::Function>(atexit)) 1485 fn->setDoesNotThrow(); 1486 1487 // Create a variable that binds the atexit to this shared object. 1488 llvm::Constant *handle = 1489 CGF.CGM.CreateRuntimeVariable(CGF.Int8Ty, "__dso_handle"); 1490 1491 llvm::Value *args[] = { 1492 llvm::ConstantExpr::getBitCast(dtor, dtorTy), 1493 llvm::ConstantExpr::getBitCast(addr, CGF.Int8PtrTy), 1494 handle 1495 }; 1496 CGF.EmitNounwindRuntimeCall(atexit, args); 1497} 1498 1499/// Register a global destructor as best as we know how. 1500void ItaniumCXXABI::registerGlobalDtor(CodeGenFunction &CGF, 1501 const VarDecl &D, 1502 llvm::Constant *dtor, 1503 llvm::Constant *addr) { 1504 // Use __cxa_atexit if available. 1505 if (CGM.getCodeGenOpts().CXAAtExit) 1506 return emitGlobalDtorWithCXAAtExit(CGF, dtor, addr, D.getTLSKind()); 1507 1508 if (D.getTLSKind()) 1509 CGM.ErrorUnsupported(&D, "non-trivial TLS destruction"); 1510 1511 // In Apple kexts, we want to add a global destructor entry. 1512 // FIXME: shouldn't this be guarded by some variable? 1513 if (CGM.getLangOpts().AppleKext) { 1514 // Generate a global destructor entry. 1515 return CGM.AddCXXDtorEntry(dtor, addr); 1516 } 1517 1518 CGF.registerGlobalDtorWithAtExit(D, dtor, addr); 1519} 1520 1521/// Get the appropriate linkage for the wrapper function. This is essentially 1522/// the weak form of the variable's linkage; every translation unit which wneeds 1523/// the wrapper emits a copy, and we want the linker to merge them. 1524static llvm::GlobalValue::LinkageTypes getThreadLocalWrapperLinkage( 1525 llvm::GlobalValue::LinkageTypes VarLinkage) { 1526 if (llvm::GlobalValue::isLinkerPrivateLinkage(VarLinkage)) 1527 return llvm::GlobalValue::LinkerPrivateWeakLinkage; 1528 // For internal linkage variables, we don't need an external or weak wrapper. 1529 if (llvm::GlobalValue::isLocalLinkage(VarLinkage)) 1530 return VarLinkage; 1531 return llvm::GlobalValue::WeakODRLinkage; 1532} 1533 1534llvm::Function * 1535ItaniumCXXABI::getOrCreateThreadLocalWrapper(const VarDecl *VD, 1536 llvm::GlobalVariable *Var) { 1537 // Mangle the name for the thread_local wrapper function. 1538 SmallString<256> WrapperName; 1539 { 1540 llvm::raw_svector_ostream Out(WrapperName); 1541 getMangleContext().mangleItaniumThreadLocalWrapper(VD, Out); 1542 Out.flush(); 1543 } 1544 1545 if (llvm::Value *V = Var->getParent()->getNamedValue(WrapperName)) 1546 return cast<llvm::Function>(V); 1547 1548 llvm::Type *RetTy = Var->getType(); 1549 if (VD->getType()->isReferenceType()) 1550 RetTy = RetTy->getPointerElementType(); 1551 1552 llvm::FunctionType *FnTy = llvm::FunctionType::get(RetTy, false); 1553 llvm::Function *Wrapper = llvm::Function::Create( 1554 FnTy, getThreadLocalWrapperLinkage(Var->getLinkage()), WrapperName.str(), 1555 &CGM.getModule()); 1556 // Always resolve references to the wrapper at link time. 1557 Wrapper->setVisibility(llvm::GlobalValue::HiddenVisibility); 1558 return Wrapper; 1559} 1560 1561void ItaniumCXXABI::EmitThreadLocalInitFuncs( 1562 llvm::ArrayRef<std::pair<const VarDecl *, llvm::GlobalVariable *> > Decls, 1563 llvm::Function *InitFunc) { 1564 for (unsigned I = 0, N = Decls.size(); I != N; ++I) { 1565 const VarDecl *VD = Decls[I].first; 1566 llvm::GlobalVariable *Var = Decls[I].second; 1567 1568 // Mangle the name for the thread_local initialization function. 1569 SmallString<256> InitFnName; 1570 { 1571 llvm::raw_svector_ostream Out(InitFnName); 1572 getMangleContext().mangleItaniumThreadLocalInit(VD, Out); 1573 Out.flush(); 1574 } 1575 1576 // If we have a definition for the variable, emit the initialization 1577 // function as an alias to the global Init function (if any). Otherwise, 1578 // produce a declaration of the initialization function. 1579 llvm::GlobalValue *Init = 0; 1580 bool InitIsInitFunc = false; 1581 if (VD->hasDefinition()) { 1582 InitIsInitFunc = true; 1583 if (InitFunc) 1584 Init = 1585 new llvm::GlobalAlias(InitFunc->getType(), Var->getLinkage(), 1586 InitFnName.str(), InitFunc, &CGM.getModule()); 1587 } else { 1588 // Emit a weak global function referring to the initialization function. 1589 // This function will not exist if the TU defining the thread_local 1590 // variable in question does not need any dynamic initialization for 1591 // its thread_local variables. 1592 llvm::FunctionType *FnTy = llvm::FunctionType::get(CGM.VoidTy, false); 1593 Init = llvm::Function::Create( 1594 FnTy, llvm::GlobalVariable::ExternalWeakLinkage, InitFnName.str(), 1595 &CGM.getModule()); 1596 } 1597 1598 if (Init) 1599 Init->setVisibility(Var->getVisibility()); 1600 1601 llvm::Function *Wrapper = getOrCreateThreadLocalWrapper(VD, Var); 1602 llvm::LLVMContext &Context = CGM.getModule().getContext(); 1603 llvm::BasicBlock *Entry = llvm::BasicBlock::Create(Context, "", Wrapper); 1604 CGBuilderTy Builder(Entry); 1605 if (InitIsInitFunc) { 1606 if (Init) 1607 Builder.CreateCall(Init); 1608 } else { 1609 // Don't know whether we have an init function. Call it if it exists. 1610 llvm::Value *Have = Builder.CreateIsNotNull(Init); 1611 llvm::BasicBlock *InitBB = llvm::BasicBlock::Create(Context, "", Wrapper); 1612 llvm::BasicBlock *ExitBB = llvm::BasicBlock::Create(Context, "", Wrapper); 1613 Builder.CreateCondBr(Have, InitBB, ExitBB); 1614 1615 Builder.SetInsertPoint(InitBB); 1616 Builder.CreateCall(Init); 1617 Builder.CreateBr(ExitBB); 1618 1619 Builder.SetInsertPoint(ExitBB); 1620 } 1621 1622 // For a reference, the result of the wrapper function is a pointer to 1623 // the referenced object. 1624 llvm::Value *Val = Var; 1625 if (VD->getType()->isReferenceType()) { 1626 llvm::LoadInst *LI = Builder.CreateLoad(Val); 1627 LI->setAlignment(CGM.getContext().getDeclAlign(VD).getQuantity()); 1628 Val = LI; 1629 } 1630 1631 Builder.CreateRet(Val); 1632 } 1633} 1634 1635LValue ItaniumCXXABI::EmitThreadLocalDeclRefExpr(CodeGenFunction &CGF, 1636 const DeclRefExpr *DRE) { 1637 const VarDecl *VD = cast<VarDecl>(DRE->getDecl()); 1638 QualType T = VD->getType(); 1639 llvm::Type *Ty = CGF.getTypes().ConvertTypeForMem(T); 1640 llvm::Value *Val = CGF.CGM.GetAddrOfGlobalVar(VD, Ty); 1641 llvm::Function *Wrapper = 1642 getOrCreateThreadLocalWrapper(VD, cast<llvm::GlobalVariable>(Val)); 1643 1644 Val = CGF.Builder.CreateCall(Wrapper); 1645 1646 LValue LV; 1647 if (VD->getType()->isReferenceType()) 1648 LV = CGF.MakeNaturalAlignAddrLValue(Val, T); 1649 else 1650 LV = CGF.MakeAddrLValue(Val, DRE->getType(), 1651 CGF.getContext().getDeclAlign(VD)); 1652 // FIXME: need setObjCGCLValueClass? 1653 return LV; 1654} 1655 1656/// Return whether the given global decl needs a VTT parameter, which it does 1657/// if it's a base constructor or destructor with virtual bases. 1658bool ItaniumCXXABI::NeedsVTTParameter(GlobalDecl GD) { 1659 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); 1660 1661 // We don't have any virtual bases, just return early. 1662 if (!MD->getParent()->getNumVBases()) 1663 return false; 1664 1665 // Check if we have a base constructor. 1666 if (isa<CXXConstructorDecl>(MD) && GD.getCtorType() == Ctor_Base) 1667 return true; 1668 1669 // Check if we have a base destructor. 1670 if (isa<CXXDestructorDecl>(MD) && GD.getDtorType() == Dtor_Base) 1671 return true; 1672 1673 return false; 1674} 1675