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/Intrinsics.h> 29#include <llvm/Target/TargetData.h> 30#include <llvm/Value.h> 31 32using namespace clang; 33using namespace CodeGen; 34 35namespace { 36class ItaniumCXXABI : public CodeGen::CGCXXABI { 37private: 38 llvm::IntegerType *PtrDiffTy; 39protected: 40 bool IsARM; 41 42 // It's a little silly for us to cache this. 43 llvm::IntegerType *getPtrDiffTy() { 44 if (!PtrDiffTy) { 45 QualType T = getContext().getPointerDiffType(); 46 llvm::Type *Ty = CGM.getTypes().ConvertType(T); 47 PtrDiffTy = cast<llvm::IntegerType>(Ty); 48 } 49 return PtrDiffTy; 50 } 51 52public: 53 ItaniumCXXABI(CodeGen::CodeGenModule &CGM, bool IsARM = false) : 54 CGCXXABI(CGM), PtrDiffTy(0), IsARM(IsARM) { } 55 56 bool isZeroInitializable(const MemberPointerType *MPT); 57 58 llvm::Type *ConvertMemberPointerType(const MemberPointerType *MPT); 59 60 llvm::Value *EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, 61 llvm::Value *&This, 62 llvm::Value *MemFnPtr, 63 const MemberPointerType *MPT); 64 65 llvm::Value *EmitMemberDataPointerAddress(CodeGenFunction &CGF, 66 llvm::Value *Base, 67 llvm::Value *MemPtr, 68 const MemberPointerType *MPT); 69 70 llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF, 71 const CastExpr *E, 72 llvm::Value *Src); 73 llvm::Constant *EmitMemberPointerConversion(const CastExpr *E, 74 llvm::Constant *Src); 75 76 llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT); 77 78 llvm::Constant *EmitMemberPointer(const CXXMethodDecl *MD); 79 llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT, 80 CharUnits offset); 81 llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT); 82 llvm::Constant *BuildMemberPointer(const CXXMethodDecl *MD, 83 CharUnits ThisAdjustment); 84 85 llvm::Value *EmitMemberPointerComparison(CodeGenFunction &CGF, 86 llvm::Value *L, 87 llvm::Value *R, 88 const MemberPointerType *MPT, 89 bool Inequality); 90 91 llvm::Value *EmitMemberPointerIsNotNull(CodeGenFunction &CGF, 92 llvm::Value *Addr, 93 const MemberPointerType *MPT); 94 95 void BuildConstructorSignature(const CXXConstructorDecl *Ctor, 96 CXXCtorType T, 97 CanQualType &ResTy, 98 SmallVectorImpl<CanQualType> &ArgTys); 99 100 void BuildDestructorSignature(const CXXDestructorDecl *Dtor, 101 CXXDtorType T, 102 CanQualType &ResTy, 103 SmallVectorImpl<CanQualType> &ArgTys); 104 105 void BuildInstanceFunctionParams(CodeGenFunction &CGF, 106 QualType &ResTy, 107 FunctionArgList &Params); 108 109 void EmitInstanceFunctionProlog(CodeGenFunction &CGF); 110 111 StringRef GetPureVirtualCallName() { return "__cxa_pure_virtual"; } 112 113 CharUnits getArrayCookieSizeImpl(QualType elementType); 114 llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF, 115 llvm::Value *NewPtr, 116 llvm::Value *NumElements, 117 const CXXNewExpr *expr, 118 QualType ElementType); 119 llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF, 120 llvm::Value *allocPtr, 121 CharUnits cookieSize); 122 123 void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D, 124 llvm::GlobalVariable *DeclPtr, bool PerformInit); 125 void registerGlobalDtor(CodeGenFunction &CGF, llvm::Constant *dtor, 126 llvm::Constant *addr); 127 128 void EmitVTables(const CXXRecordDecl *Class); 129}; 130 131class ARMCXXABI : public ItaniumCXXABI { 132public: 133 ARMCXXABI(CodeGen::CodeGenModule &CGM) : ItaniumCXXABI(CGM, /*ARM*/ true) {} 134 135 void BuildConstructorSignature(const CXXConstructorDecl *Ctor, 136 CXXCtorType T, 137 CanQualType &ResTy, 138 SmallVectorImpl<CanQualType> &ArgTys); 139 140 void BuildDestructorSignature(const CXXDestructorDecl *Dtor, 141 CXXDtorType T, 142 CanQualType &ResTy, 143 SmallVectorImpl<CanQualType> &ArgTys); 144 145 void BuildInstanceFunctionParams(CodeGenFunction &CGF, 146 QualType &ResTy, 147 FunctionArgList &Params); 148 149 void EmitInstanceFunctionProlog(CodeGenFunction &CGF); 150 151 void EmitReturnFromThunk(CodeGenFunction &CGF, RValue RV, QualType ResTy); 152 153 CharUnits getArrayCookieSizeImpl(QualType elementType); 154 llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF, 155 llvm::Value *NewPtr, 156 llvm::Value *NumElements, 157 const CXXNewExpr *expr, 158 QualType ElementType); 159 llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF, llvm::Value *allocPtr, 160 CharUnits cookieSize); 161 162private: 163 /// \brief Returns true if the given instance method is one of the 164 /// kinds that the ARM ABI says returns 'this'. 165 static bool HasThisReturn(GlobalDecl GD) { 166 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); 167 return ((isa<CXXDestructorDecl>(MD) && GD.getDtorType() != Dtor_Deleting) || 168 (isa<CXXConstructorDecl>(MD))); 169 } 170}; 171} 172 173CodeGen::CGCXXABI *CodeGen::CreateItaniumCXXABI(CodeGenModule &CGM) { 174 return new ItaniumCXXABI(CGM); 175} 176 177CodeGen::CGCXXABI *CodeGen::CreateARMCXXABI(CodeGenModule &CGM) { 178 return new ARMCXXABI(CGM); 179} 180 181llvm::Type * 182ItaniumCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) { 183 if (MPT->isMemberDataPointer()) 184 return getPtrDiffTy(); 185 return llvm::StructType::get(getPtrDiffTy(), getPtrDiffTy(), NULL); 186} 187 188/// In the Itanium and ARM ABIs, method pointers have the form: 189/// struct { ptrdiff_t ptr; ptrdiff_t adj; } memptr; 190/// 191/// In the Itanium ABI: 192/// - method pointers are virtual if (memptr.ptr & 1) is nonzero 193/// - the this-adjustment is (memptr.adj) 194/// - the virtual offset is (memptr.ptr - 1) 195/// 196/// In the ARM ABI: 197/// - method pointers are virtual if (memptr.adj & 1) is nonzero 198/// - the this-adjustment is (memptr.adj >> 1) 199/// - the virtual offset is (memptr.ptr) 200/// ARM uses 'adj' for the virtual flag because Thumb functions 201/// may be only single-byte aligned. 202/// 203/// If the member is virtual, the adjusted 'this' pointer points 204/// to a vtable pointer from which the virtual offset is applied. 205/// 206/// If the member is non-virtual, memptr.ptr is the address of 207/// the function to call. 208llvm::Value * 209ItaniumCXXABI::EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, 210 llvm::Value *&This, 211 llvm::Value *MemFnPtr, 212 const MemberPointerType *MPT) { 213 CGBuilderTy &Builder = CGF.Builder; 214 215 const FunctionProtoType *FPT = 216 MPT->getPointeeType()->getAs<FunctionProtoType>(); 217 const CXXRecordDecl *RD = 218 cast<CXXRecordDecl>(MPT->getClass()->getAs<RecordType>()->getDecl()); 219 220 llvm::FunctionType *FTy = 221 CGM.getTypes().GetFunctionType( 222 CGM.getTypes().arrangeCXXMethodType(RD, FPT)); 223 224 llvm::IntegerType *ptrdiff = getPtrDiffTy(); 225 llvm::Constant *ptrdiff_1 = llvm::ConstantInt::get(ptrdiff, 1); 226 227 llvm::BasicBlock *FnVirtual = CGF.createBasicBlock("memptr.virtual"); 228 llvm::BasicBlock *FnNonVirtual = CGF.createBasicBlock("memptr.nonvirtual"); 229 llvm::BasicBlock *FnEnd = CGF.createBasicBlock("memptr.end"); 230 231 // Extract memptr.adj, which is in the second field. 232 llvm::Value *RawAdj = Builder.CreateExtractValue(MemFnPtr, 1, "memptr.adj"); 233 234 // Compute the true adjustment. 235 llvm::Value *Adj = RawAdj; 236 if (IsARM) 237 Adj = Builder.CreateAShr(Adj, ptrdiff_1, "memptr.adj.shifted"); 238 239 // Apply the adjustment and cast back to the original struct type 240 // for consistency. 241 llvm::Value *Ptr = Builder.CreateBitCast(This, Builder.getInt8PtrTy()); 242 Ptr = Builder.CreateInBoundsGEP(Ptr, Adj); 243 This = Builder.CreateBitCast(Ptr, This->getType(), "this.adjusted"); 244 245 // Load the function pointer. 246 llvm::Value *FnAsInt = Builder.CreateExtractValue(MemFnPtr, 0, "memptr.ptr"); 247 248 // If the LSB in the function pointer is 1, the function pointer points to 249 // a virtual function. 250 llvm::Value *IsVirtual; 251 if (IsARM) 252 IsVirtual = Builder.CreateAnd(RawAdj, ptrdiff_1); 253 else 254 IsVirtual = Builder.CreateAnd(FnAsInt, ptrdiff_1); 255 IsVirtual = Builder.CreateIsNotNull(IsVirtual, "memptr.isvirtual"); 256 Builder.CreateCondBr(IsVirtual, FnVirtual, FnNonVirtual); 257 258 // In the virtual path, the adjustment left 'This' pointing to the 259 // vtable of the correct base subobject. The "function pointer" is an 260 // offset within the vtable (+1 for the virtual flag on non-ARM). 261 CGF.EmitBlock(FnVirtual); 262 263 // Cast the adjusted this to a pointer to vtable pointer and load. 264 llvm::Type *VTableTy = Builder.getInt8PtrTy(); 265 llvm::Value *VTable = Builder.CreateBitCast(This, VTableTy->getPointerTo()); 266 VTable = Builder.CreateLoad(VTable, "memptr.vtable"); 267 268 // Apply the offset. 269 llvm::Value *VTableOffset = FnAsInt; 270 if (!IsARM) VTableOffset = Builder.CreateSub(VTableOffset, ptrdiff_1); 271 VTable = Builder.CreateGEP(VTable, VTableOffset); 272 273 // Load the virtual function to call. 274 VTable = Builder.CreateBitCast(VTable, FTy->getPointerTo()->getPointerTo()); 275 llvm::Value *VirtualFn = Builder.CreateLoad(VTable, "memptr.virtualfn"); 276 CGF.EmitBranch(FnEnd); 277 278 // In the non-virtual path, the function pointer is actually a 279 // function pointer. 280 CGF.EmitBlock(FnNonVirtual); 281 llvm::Value *NonVirtualFn = 282 Builder.CreateIntToPtr(FnAsInt, FTy->getPointerTo(), "memptr.nonvirtualfn"); 283 284 // We're done. 285 CGF.EmitBlock(FnEnd); 286 llvm::PHINode *Callee = Builder.CreatePHI(FTy->getPointerTo(), 2); 287 Callee->addIncoming(VirtualFn, FnVirtual); 288 Callee->addIncoming(NonVirtualFn, FnNonVirtual); 289 return Callee; 290} 291 292/// Compute an l-value by applying the given pointer-to-member to a 293/// base object. 294llvm::Value *ItaniumCXXABI::EmitMemberDataPointerAddress(CodeGenFunction &CGF, 295 llvm::Value *Base, 296 llvm::Value *MemPtr, 297 const MemberPointerType *MPT) { 298 assert(MemPtr->getType() == getPtrDiffTy()); 299 300 CGBuilderTy &Builder = CGF.Builder; 301 302 unsigned AS = cast<llvm::PointerType>(Base->getType())->getAddressSpace(); 303 304 // Cast to char*. 305 Base = Builder.CreateBitCast(Base, Builder.getInt8Ty()->getPointerTo(AS)); 306 307 // Apply the offset, which we assume is non-null. 308 llvm::Value *Addr = Builder.CreateInBoundsGEP(Base, MemPtr, "memptr.offset"); 309 310 // Cast the address to the appropriate pointer type, adopting the 311 // address space of the base pointer. 312 llvm::Type *PType 313 = CGF.ConvertTypeForMem(MPT->getPointeeType())->getPointerTo(AS); 314 return Builder.CreateBitCast(Addr, PType); 315} 316 317/// Perform a bitcast, derived-to-base, or base-to-derived member pointer 318/// conversion. 319/// 320/// Bitcast conversions are always a no-op under Itanium. 321/// 322/// Obligatory offset/adjustment diagram: 323/// <-- offset --> <-- adjustment --> 324/// |--------------------------|----------------------|--------------------| 325/// ^Derived address point ^Base address point ^Member address point 326/// 327/// So when converting a base member pointer to a derived member pointer, 328/// we add the offset to the adjustment because the address point has 329/// decreased; and conversely, when converting a derived MP to a base MP 330/// we subtract the offset from the adjustment because the address point 331/// has increased. 332/// 333/// The standard forbids (at compile time) conversion to and from 334/// virtual bases, which is why we don't have to consider them here. 335/// 336/// The standard forbids (at run time) casting a derived MP to a base 337/// MP when the derived MP does not point to a member of the base. 338/// This is why -1 is a reasonable choice for null data member 339/// pointers. 340llvm::Value * 341ItaniumCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF, 342 const CastExpr *E, 343 llvm::Value *src) { 344 assert(E->getCastKind() == CK_DerivedToBaseMemberPointer || 345 E->getCastKind() == CK_BaseToDerivedMemberPointer || 346 E->getCastKind() == CK_ReinterpretMemberPointer); 347 348 // Under Itanium, reinterprets don't require any additional processing. 349 if (E->getCastKind() == CK_ReinterpretMemberPointer) return src; 350 351 // Use constant emission if we can. 352 if (isa<llvm::Constant>(src)) 353 return EmitMemberPointerConversion(E, cast<llvm::Constant>(src)); 354 355 llvm::Constant *adj = getMemberPointerAdjustment(E); 356 if (!adj) return src; 357 358 CGBuilderTy &Builder = CGF.Builder; 359 bool isDerivedToBase = (E->getCastKind() == CK_DerivedToBaseMemberPointer); 360 361 const MemberPointerType *destTy = 362 E->getType()->castAs<MemberPointerType>(); 363 364 // For member data pointers, this is just a matter of adding the 365 // offset if the source is non-null. 366 if (destTy->isMemberDataPointer()) { 367 llvm::Value *dst; 368 if (isDerivedToBase) 369 dst = Builder.CreateNSWSub(src, adj, "adj"); 370 else 371 dst = Builder.CreateNSWAdd(src, adj, "adj"); 372 373 // Null check. 374 llvm::Value *null = llvm::Constant::getAllOnesValue(src->getType()); 375 llvm::Value *isNull = Builder.CreateICmpEQ(src, null, "memptr.isnull"); 376 return Builder.CreateSelect(isNull, src, dst); 377 } 378 379 // The this-adjustment is left-shifted by 1 on ARM. 380 if (IsARM) { 381 uint64_t offset = cast<llvm::ConstantInt>(adj)->getZExtValue(); 382 offset <<= 1; 383 adj = llvm::ConstantInt::get(adj->getType(), offset); 384 } 385 386 llvm::Value *srcAdj = Builder.CreateExtractValue(src, 1, "src.adj"); 387 llvm::Value *dstAdj; 388 if (isDerivedToBase) 389 dstAdj = Builder.CreateNSWSub(srcAdj, adj, "adj"); 390 else 391 dstAdj = Builder.CreateNSWAdd(srcAdj, adj, "adj"); 392 393 return Builder.CreateInsertValue(src, dstAdj, 1); 394} 395 396llvm::Constant * 397ItaniumCXXABI::EmitMemberPointerConversion(const CastExpr *E, 398 llvm::Constant *src) { 399 assert(E->getCastKind() == CK_DerivedToBaseMemberPointer || 400 E->getCastKind() == CK_BaseToDerivedMemberPointer || 401 E->getCastKind() == CK_ReinterpretMemberPointer); 402 403 // Under Itanium, reinterprets don't require any additional processing. 404 if (E->getCastKind() == CK_ReinterpretMemberPointer) return src; 405 406 // If the adjustment is trivial, we don't need to do anything. 407 llvm::Constant *adj = getMemberPointerAdjustment(E); 408 if (!adj) return src; 409 410 bool isDerivedToBase = (E->getCastKind() == CK_DerivedToBaseMemberPointer); 411 412 const MemberPointerType *destTy = 413 E->getType()->castAs<MemberPointerType>(); 414 415 // For member data pointers, this is just a matter of adding the 416 // offset if the source is non-null. 417 if (destTy->isMemberDataPointer()) { 418 // null maps to null. 419 if (src->isAllOnesValue()) return src; 420 421 if (isDerivedToBase) 422 return llvm::ConstantExpr::getNSWSub(src, adj); 423 else 424 return llvm::ConstantExpr::getNSWAdd(src, adj); 425 } 426 427 // The this-adjustment is left-shifted by 1 on ARM. 428 if (IsARM) { 429 uint64_t offset = cast<llvm::ConstantInt>(adj)->getZExtValue(); 430 offset <<= 1; 431 adj = llvm::ConstantInt::get(adj->getType(), offset); 432 } 433 434 llvm::Constant *srcAdj = llvm::ConstantExpr::getExtractValue(src, 1); 435 llvm::Constant *dstAdj; 436 if (isDerivedToBase) 437 dstAdj = llvm::ConstantExpr::getNSWSub(srcAdj, adj); 438 else 439 dstAdj = llvm::ConstantExpr::getNSWAdd(srcAdj, adj); 440 441 return llvm::ConstantExpr::getInsertValue(src, dstAdj, 1); 442} 443 444llvm::Constant * 445ItaniumCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) { 446 llvm::Type *ptrdiff_t = getPtrDiffTy(); 447 448 // Itanium C++ ABI 2.3: 449 // A NULL pointer is represented as -1. 450 if (MPT->isMemberDataPointer()) 451 return llvm::ConstantInt::get(ptrdiff_t, -1ULL, /*isSigned=*/true); 452 453 llvm::Constant *Zero = llvm::ConstantInt::get(ptrdiff_t, 0); 454 llvm::Constant *Values[2] = { Zero, Zero }; 455 return llvm::ConstantStruct::getAnon(Values); 456} 457 458llvm::Constant * 459ItaniumCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT, 460 CharUnits offset) { 461 // Itanium C++ ABI 2.3: 462 // A pointer to data member is an offset from the base address of 463 // the class object containing it, represented as a ptrdiff_t 464 return llvm::ConstantInt::get(getPtrDiffTy(), offset.getQuantity()); 465} 466 467llvm::Constant *ItaniumCXXABI::EmitMemberPointer(const CXXMethodDecl *MD) { 468 return BuildMemberPointer(MD, CharUnits::Zero()); 469} 470 471llvm::Constant *ItaniumCXXABI::BuildMemberPointer(const CXXMethodDecl *MD, 472 CharUnits ThisAdjustment) { 473 assert(MD->isInstance() && "Member function must not be static!"); 474 MD = MD->getCanonicalDecl(); 475 476 CodeGenTypes &Types = CGM.getTypes(); 477 llvm::Type *ptrdiff_t = getPtrDiffTy(); 478 479 // Get the function pointer (or index if this is a virtual function). 480 llvm::Constant *MemPtr[2]; 481 if (MD->isVirtual()) { 482 uint64_t Index = CGM.getVTableContext().getMethodVTableIndex(MD); 483 484 const ASTContext &Context = getContext(); 485 CharUnits PointerWidth = 486 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0)); 487 uint64_t VTableOffset = (Index * PointerWidth.getQuantity()); 488 489 if (IsARM) { 490 // ARM C++ ABI 3.2.1: 491 // This ABI specifies that adj contains twice the this 492 // adjustment, plus 1 if the member function is virtual. The 493 // least significant bit of adj then makes exactly the same 494 // discrimination as the least significant bit of ptr does for 495 // Itanium. 496 MemPtr[0] = llvm::ConstantInt::get(ptrdiff_t, VTableOffset); 497 MemPtr[1] = llvm::ConstantInt::get(ptrdiff_t, 498 2 * ThisAdjustment.getQuantity() + 1); 499 } else { 500 // Itanium C++ ABI 2.3: 501 // For a virtual function, [the pointer field] is 1 plus the 502 // virtual table offset (in bytes) of the function, 503 // represented as a ptrdiff_t. 504 MemPtr[0] = llvm::ConstantInt::get(ptrdiff_t, VTableOffset + 1); 505 MemPtr[1] = llvm::ConstantInt::get(ptrdiff_t, 506 ThisAdjustment.getQuantity()); 507 } 508 } else { 509 const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>(); 510 llvm::Type *Ty; 511 // Check whether the function has a computable LLVM signature. 512 if (Types.isFuncTypeConvertible(FPT)) { 513 // The function has a computable LLVM signature; use the correct type. 514 Ty = Types.GetFunctionType(Types.arrangeCXXMethodDeclaration(MD)); 515 } else { 516 // Use an arbitrary non-function type to tell GetAddrOfFunction that the 517 // function type is incomplete. 518 Ty = ptrdiff_t; 519 } 520 llvm::Constant *addr = CGM.GetAddrOfFunction(MD, Ty); 521 522 MemPtr[0] = llvm::ConstantExpr::getPtrToInt(addr, ptrdiff_t); 523 MemPtr[1] = llvm::ConstantInt::get(ptrdiff_t, (IsARM ? 2 : 1) * 524 ThisAdjustment.getQuantity()); 525 } 526 527 return llvm::ConstantStruct::getAnon(MemPtr); 528} 529 530llvm::Constant *ItaniumCXXABI::EmitMemberPointer(const APValue &MP, 531 QualType MPType) { 532 const MemberPointerType *MPT = MPType->castAs<MemberPointerType>(); 533 const ValueDecl *MPD = MP.getMemberPointerDecl(); 534 if (!MPD) 535 return EmitNullMemberPointer(MPT); 536 537 // Compute the this-adjustment. 538 CharUnits ThisAdjustment = CharUnits::Zero(); 539 ArrayRef<const CXXRecordDecl*> Path = MP.getMemberPointerPath(); 540 bool DerivedMember = MP.isMemberPointerToDerivedMember(); 541 const CXXRecordDecl *RD = cast<CXXRecordDecl>(MPD->getDeclContext()); 542 for (unsigned I = 0, N = Path.size(); I != N; ++I) { 543 const CXXRecordDecl *Base = RD; 544 const CXXRecordDecl *Derived = Path[I]; 545 if (DerivedMember) 546 std::swap(Base, Derived); 547 ThisAdjustment += 548 getContext().getASTRecordLayout(Derived).getBaseClassOffset(Base); 549 RD = Path[I]; 550 } 551 if (DerivedMember) 552 ThisAdjustment = -ThisAdjustment; 553 554 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MPD)) 555 return BuildMemberPointer(MD, ThisAdjustment); 556 557 CharUnits FieldOffset = 558 getContext().toCharUnitsFromBits(getContext().getFieldOffset(MPD)); 559 return EmitMemberDataPointer(MPT, ThisAdjustment + FieldOffset); 560} 561 562/// The comparison algorithm is pretty easy: the member pointers are 563/// the same if they're either bitwise identical *or* both null. 564/// 565/// ARM is different here only because null-ness is more complicated. 566llvm::Value * 567ItaniumCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF, 568 llvm::Value *L, 569 llvm::Value *R, 570 const MemberPointerType *MPT, 571 bool Inequality) { 572 CGBuilderTy &Builder = CGF.Builder; 573 574 llvm::ICmpInst::Predicate Eq; 575 llvm::Instruction::BinaryOps And, Or; 576 if (Inequality) { 577 Eq = llvm::ICmpInst::ICMP_NE; 578 And = llvm::Instruction::Or; 579 Or = llvm::Instruction::And; 580 } else { 581 Eq = llvm::ICmpInst::ICMP_EQ; 582 And = llvm::Instruction::And; 583 Or = llvm::Instruction::Or; 584 } 585 586 // Member data pointers are easy because there's a unique null 587 // value, so it just comes down to bitwise equality. 588 if (MPT->isMemberDataPointer()) 589 return Builder.CreateICmp(Eq, L, R); 590 591 // For member function pointers, the tautologies are more complex. 592 // The Itanium tautology is: 593 // (L == R) <==> (L.ptr == R.ptr && (L.ptr == 0 || L.adj == R.adj)) 594 // The ARM tautology is: 595 // (L == R) <==> (L.ptr == R.ptr && 596 // (L.adj == R.adj || 597 // (L.ptr == 0 && ((L.adj|R.adj) & 1) == 0))) 598 // The inequality tautologies have exactly the same structure, except 599 // applying De Morgan's laws. 600 601 llvm::Value *LPtr = Builder.CreateExtractValue(L, 0, "lhs.memptr.ptr"); 602 llvm::Value *RPtr = Builder.CreateExtractValue(R, 0, "rhs.memptr.ptr"); 603 604 // This condition tests whether L.ptr == R.ptr. This must always be 605 // true for equality to hold. 606 llvm::Value *PtrEq = Builder.CreateICmp(Eq, LPtr, RPtr, "cmp.ptr"); 607 608 // This condition, together with the assumption that L.ptr == R.ptr, 609 // tests whether the pointers are both null. ARM imposes an extra 610 // condition. 611 llvm::Value *Zero = llvm::Constant::getNullValue(LPtr->getType()); 612 llvm::Value *EqZero = Builder.CreateICmp(Eq, LPtr, Zero, "cmp.ptr.null"); 613 614 // This condition tests whether L.adj == R.adj. If this isn't 615 // true, the pointers are unequal unless they're both null. 616 llvm::Value *LAdj = Builder.CreateExtractValue(L, 1, "lhs.memptr.adj"); 617 llvm::Value *RAdj = Builder.CreateExtractValue(R, 1, "rhs.memptr.adj"); 618 llvm::Value *AdjEq = Builder.CreateICmp(Eq, LAdj, RAdj, "cmp.adj"); 619 620 // Null member function pointers on ARM clear the low bit of Adj, 621 // so the zero condition has to check that neither low bit is set. 622 if (IsARM) { 623 llvm::Value *One = llvm::ConstantInt::get(LPtr->getType(), 1); 624 625 // Compute (l.adj | r.adj) & 1 and test it against zero. 626 llvm::Value *OrAdj = Builder.CreateOr(LAdj, RAdj, "or.adj"); 627 llvm::Value *OrAdjAnd1 = Builder.CreateAnd(OrAdj, One); 628 llvm::Value *OrAdjAnd1EqZero = Builder.CreateICmp(Eq, OrAdjAnd1, Zero, 629 "cmp.or.adj"); 630 EqZero = Builder.CreateBinOp(And, EqZero, OrAdjAnd1EqZero); 631 } 632 633 // Tie together all our conditions. 634 llvm::Value *Result = Builder.CreateBinOp(Or, EqZero, AdjEq); 635 Result = Builder.CreateBinOp(And, PtrEq, Result, 636 Inequality ? "memptr.ne" : "memptr.eq"); 637 return Result; 638} 639 640llvm::Value * 641ItaniumCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF, 642 llvm::Value *MemPtr, 643 const MemberPointerType *MPT) { 644 CGBuilderTy &Builder = CGF.Builder; 645 646 /// For member data pointers, this is just a check against -1. 647 if (MPT->isMemberDataPointer()) { 648 assert(MemPtr->getType() == getPtrDiffTy()); 649 llvm::Value *NegativeOne = 650 llvm::Constant::getAllOnesValue(MemPtr->getType()); 651 return Builder.CreateICmpNE(MemPtr, NegativeOne, "memptr.tobool"); 652 } 653 654 // In Itanium, a member function pointer is not null if 'ptr' is not null. 655 llvm::Value *Ptr = Builder.CreateExtractValue(MemPtr, 0, "memptr.ptr"); 656 657 llvm::Constant *Zero = llvm::ConstantInt::get(Ptr->getType(), 0); 658 llvm::Value *Result = Builder.CreateICmpNE(Ptr, Zero, "memptr.tobool"); 659 660 // On ARM, a member function pointer is also non-null if the low bit of 'adj' 661 // (the virtual bit) is set. 662 if (IsARM) { 663 llvm::Constant *One = llvm::ConstantInt::get(Ptr->getType(), 1); 664 llvm::Value *Adj = Builder.CreateExtractValue(MemPtr, 1, "memptr.adj"); 665 llvm::Value *VirtualBit = Builder.CreateAnd(Adj, One, "memptr.virtualbit"); 666 llvm::Value *IsVirtual = Builder.CreateICmpNE(VirtualBit, Zero, 667 "memptr.isvirtual"); 668 Result = Builder.CreateOr(Result, IsVirtual); 669 } 670 671 return Result; 672} 673 674/// The Itanium ABI requires non-zero initialization only for data 675/// member pointers, for which '0' is a valid offset. 676bool ItaniumCXXABI::isZeroInitializable(const MemberPointerType *MPT) { 677 return MPT->getPointeeType()->isFunctionType(); 678} 679 680/// The generic ABI passes 'this', plus a VTT if it's initializing a 681/// base subobject. 682void ItaniumCXXABI::BuildConstructorSignature(const CXXConstructorDecl *Ctor, 683 CXXCtorType Type, 684 CanQualType &ResTy, 685 SmallVectorImpl<CanQualType> &ArgTys) { 686 ASTContext &Context = getContext(); 687 688 // 'this' is already there. 689 690 // Check if we need to add a VTT parameter (which has type void **). 691 if (Type == Ctor_Base && Ctor->getParent()->getNumVBases() != 0) 692 ArgTys.push_back(Context.getPointerType(Context.VoidPtrTy)); 693} 694 695/// The ARM ABI does the same as the Itanium ABI, but returns 'this'. 696void ARMCXXABI::BuildConstructorSignature(const CXXConstructorDecl *Ctor, 697 CXXCtorType Type, 698 CanQualType &ResTy, 699 SmallVectorImpl<CanQualType> &ArgTys) { 700 ItaniumCXXABI::BuildConstructorSignature(Ctor, Type, ResTy, ArgTys); 701 ResTy = ArgTys[0]; 702} 703 704/// The generic ABI passes 'this', plus a VTT if it's destroying a 705/// base subobject. 706void ItaniumCXXABI::BuildDestructorSignature(const CXXDestructorDecl *Dtor, 707 CXXDtorType Type, 708 CanQualType &ResTy, 709 SmallVectorImpl<CanQualType> &ArgTys) { 710 ASTContext &Context = getContext(); 711 712 // 'this' is already there. 713 714 // Check if we need to add a VTT parameter (which has type void **). 715 if (Type == Dtor_Base && Dtor->getParent()->getNumVBases() != 0) 716 ArgTys.push_back(Context.getPointerType(Context.VoidPtrTy)); 717} 718 719/// The ARM ABI does the same as the Itanium ABI, but returns 'this' 720/// for non-deleting destructors. 721void ARMCXXABI::BuildDestructorSignature(const CXXDestructorDecl *Dtor, 722 CXXDtorType Type, 723 CanQualType &ResTy, 724 SmallVectorImpl<CanQualType> &ArgTys) { 725 ItaniumCXXABI::BuildDestructorSignature(Dtor, Type, ResTy, ArgTys); 726 727 if (Type != Dtor_Deleting) 728 ResTy = ArgTys[0]; 729} 730 731void ItaniumCXXABI::BuildInstanceFunctionParams(CodeGenFunction &CGF, 732 QualType &ResTy, 733 FunctionArgList &Params) { 734 /// Create the 'this' variable. 735 BuildThisParam(CGF, Params); 736 737 const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl()); 738 assert(MD->isInstance()); 739 740 // Check if we need a VTT parameter as well. 741 if (CodeGenVTables::needsVTTParameter(CGF.CurGD)) { 742 ASTContext &Context = getContext(); 743 744 // FIXME: avoid the fake decl 745 QualType T = Context.getPointerType(Context.VoidPtrTy); 746 ImplicitParamDecl *VTTDecl 747 = ImplicitParamDecl::Create(Context, 0, MD->getLocation(), 748 &Context.Idents.get("vtt"), T); 749 Params.push_back(VTTDecl); 750 getVTTDecl(CGF) = VTTDecl; 751 } 752} 753 754void ARMCXXABI::BuildInstanceFunctionParams(CodeGenFunction &CGF, 755 QualType &ResTy, 756 FunctionArgList &Params) { 757 ItaniumCXXABI::BuildInstanceFunctionParams(CGF, ResTy, Params); 758 759 // Return 'this' from certain constructors and destructors. 760 if (HasThisReturn(CGF.CurGD)) 761 ResTy = Params[0]->getType(); 762} 763 764void ItaniumCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) { 765 /// Initialize the 'this' slot. 766 EmitThisParam(CGF); 767 768 /// Initialize the 'vtt' slot if needed. 769 if (getVTTDecl(CGF)) { 770 getVTTValue(CGF) 771 = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(getVTTDecl(CGF)), 772 "vtt"); 773 } 774} 775 776void ARMCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) { 777 ItaniumCXXABI::EmitInstanceFunctionProlog(CGF); 778 779 /// Initialize the return slot to 'this' at the start of the 780 /// function. 781 if (HasThisReturn(CGF.CurGD)) 782 CGF.Builder.CreateStore(getThisValue(CGF), CGF.ReturnValue); 783} 784 785void ARMCXXABI::EmitReturnFromThunk(CodeGenFunction &CGF, 786 RValue RV, QualType ResultType) { 787 if (!isa<CXXDestructorDecl>(CGF.CurGD.getDecl())) 788 return ItaniumCXXABI::EmitReturnFromThunk(CGF, RV, ResultType); 789 790 // Destructor thunks in the ARM ABI have indeterminate results. 791 llvm::Type *T = 792 cast<llvm::PointerType>(CGF.ReturnValue->getType())->getElementType(); 793 RValue Undef = RValue::get(llvm::UndefValue::get(T)); 794 return ItaniumCXXABI::EmitReturnFromThunk(CGF, Undef, ResultType); 795} 796 797/************************** Array allocation cookies **************************/ 798 799CharUnits ItaniumCXXABI::getArrayCookieSizeImpl(QualType elementType) { 800 // The array cookie is a size_t; pad that up to the element alignment. 801 // The cookie is actually right-justified in that space. 802 return std::max(CharUnits::fromQuantity(CGM.SizeSizeInBytes), 803 CGM.getContext().getTypeAlignInChars(elementType)); 804} 805 806llvm::Value *ItaniumCXXABI::InitializeArrayCookie(CodeGenFunction &CGF, 807 llvm::Value *NewPtr, 808 llvm::Value *NumElements, 809 const CXXNewExpr *expr, 810 QualType ElementType) { 811 assert(requiresArrayCookie(expr)); 812 813 unsigned AS = cast<llvm::PointerType>(NewPtr->getType())->getAddressSpace(); 814 815 ASTContext &Ctx = getContext(); 816 QualType SizeTy = Ctx.getSizeType(); 817 CharUnits SizeSize = Ctx.getTypeSizeInChars(SizeTy); 818 819 // The size of the cookie. 820 CharUnits CookieSize = 821 std::max(SizeSize, Ctx.getTypeAlignInChars(ElementType)); 822 assert(CookieSize == getArrayCookieSizeImpl(ElementType)); 823 824 // Compute an offset to the cookie. 825 llvm::Value *CookiePtr = NewPtr; 826 CharUnits CookieOffset = CookieSize - SizeSize; 827 if (!CookieOffset.isZero()) 828 CookiePtr = CGF.Builder.CreateConstInBoundsGEP1_64(CookiePtr, 829 CookieOffset.getQuantity()); 830 831 // Write the number of elements into the appropriate slot. 832 llvm::Value *NumElementsPtr 833 = CGF.Builder.CreateBitCast(CookiePtr, 834 CGF.ConvertType(SizeTy)->getPointerTo(AS)); 835 CGF.Builder.CreateStore(NumElements, NumElementsPtr); 836 837 // Finally, compute a pointer to the actual data buffer by skipping 838 // over the cookie completely. 839 return CGF.Builder.CreateConstInBoundsGEP1_64(NewPtr, 840 CookieSize.getQuantity()); 841} 842 843llvm::Value *ItaniumCXXABI::readArrayCookieImpl(CodeGenFunction &CGF, 844 llvm::Value *allocPtr, 845 CharUnits cookieSize) { 846 // The element size is right-justified in the cookie. 847 llvm::Value *numElementsPtr = allocPtr; 848 CharUnits numElementsOffset = 849 cookieSize - CharUnits::fromQuantity(CGF.SizeSizeInBytes); 850 if (!numElementsOffset.isZero()) 851 numElementsPtr = 852 CGF.Builder.CreateConstInBoundsGEP1_64(numElementsPtr, 853 numElementsOffset.getQuantity()); 854 855 unsigned AS = cast<llvm::PointerType>(allocPtr->getType())->getAddressSpace(); 856 numElementsPtr = 857 CGF.Builder.CreateBitCast(numElementsPtr, CGF.SizeTy->getPointerTo(AS)); 858 return CGF.Builder.CreateLoad(numElementsPtr); 859} 860 861CharUnits ARMCXXABI::getArrayCookieSizeImpl(QualType elementType) { 862 // On ARM, the cookie is always: 863 // struct array_cookie { 864 // std::size_t element_size; // element_size != 0 865 // std::size_t element_count; 866 // }; 867 // TODO: what should we do if the allocated type actually wants 868 // greater alignment? 869 return CharUnits::fromQuantity(2 * CGM.SizeSizeInBytes); 870} 871 872llvm::Value *ARMCXXABI::InitializeArrayCookie(CodeGenFunction &CGF, 873 llvm::Value *NewPtr, 874 llvm::Value *NumElements, 875 const CXXNewExpr *expr, 876 QualType ElementType) { 877 assert(requiresArrayCookie(expr)); 878 879 // NewPtr is a char*. 880 881 unsigned AS = cast<llvm::PointerType>(NewPtr->getType())->getAddressSpace(); 882 883 ASTContext &Ctx = getContext(); 884 CharUnits SizeSize = Ctx.getTypeSizeInChars(Ctx.getSizeType()); 885 llvm::IntegerType *SizeTy = 886 cast<llvm::IntegerType>(CGF.ConvertType(Ctx.getSizeType())); 887 888 // The cookie is always at the start of the buffer. 889 llvm::Value *CookiePtr = NewPtr; 890 891 // The first element is the element size. 892 CookiePtr = CGF.Builder.CreateBitCast(CookiePtr, SizeTy->getPointerTo(AS)); 893 llvm::Value *ElementSize = llvm::ConstantInt::get(SizeTy, 894 Ctx.getTypeSizeInChars(ElementType).getQuantity()); 895 CGF.Builder.CreateStore(ElementSize, CookiePtr); 896 897 // The second element is the element count. 898 CookiePtr = CGF.Builder.CreateConstInBoundsGEP1_32(CookiePtr, 1); 899 CGF.Builder.CreateStore(NumElements, CookiePtr); 900 901 // Finally, compute a pointer to the actual data buffer by skipping 902 // over the cookie completely. 903 CharUnits CookieSize = 2 * SizeSize; 904 return CGF.Builder.CreateConstInBoundsGEP1_64(NewPtr, 905 CookieSize.getQuantity()); 906} 907 908llvm::Value *ARMCXXABI::readArrayCookieImpl(CodeGenFunction &CGF, 909 llvm::Value *allocPtr, 910 CharUnits cookieSize) { 911 // The number of elements is at offset sizeof(size_t) relative to 912 // the allocated pointer. 913 llvm::Value *numElementsPtr 914 = CGF.Builder.CreateConstInBoundsGEP1_64(allocPtr, CGF.SizeSizeInBytes); 915 916 unsigned AS = cast<llvm::PointerType>(allocPtr->getType())->getAddressSpace(); 917 numElementsPtr = 918 CGF.Builder.CreateBitCast(numElementsPtr, CGF.SizeTy->getPointerTo(AS)); 919 return CGF.Builder.CreateLoad(numElementsPtr); 920} 921 922/*********************** Static local initialization **************************/ 923 924static llvm::Constant *getGuardAcquireFn(CodeGenModule &CGM, 925 llvm::PointerType *GuardPtrTy) { 926 // int __cxa_guard_acquire(__guard *guard_object); 927 llvm::FunctionType *FTy = 928 llvm::FunctionType::get(CGM.getTypes().ConvertType(CGM.getContext().IntTy), 929 GuardPtrTy, /*isVarArg=*/false); 930 931 return CGM.CreateRuntimeFunction(FTy, "__cxa_guard_acquire", 932 llvm::Attribute::NoUnwind); 933} 934 935static llvm::Constant *getGuardReleaseFn(CodeGenModule &CGM, 936 llvm::PointerType *GuardPtrTy) { 937 // void __cxa_guard_release(__guard *guard_object); 938 llvm::FunctionType *FTy = 939 llvm::FunctionType::get(CGM.VoidTy, GuardPtrTy, /*isVarArg=*/false); 940 941 return CGM.CreateRuntimeFunction(FTy, "__cxa_guard_release", 942 llvm::Attribute::NoUnwind); 943} 944 945static llvm::Constant *getGuardAbortFn(CodeGenModule &CGM, 946 llvm::PointerType *GuardPtrTy) { 947 // void __cxa_guard_abort(__guard *guard_object); 948 llvm::FunctionType *FTy = 949 llvm::FunctionType::get(CGM.VoidTy, GuardPtrTy, /*isVarArg=*/false); 950 951 return CGM.CreateRuntimeFunction(FTy, "__cxa_guard_abort", 952 llvm::Attribute::NoUnwind); 953} 954 955namespace { 956 struct CallGuardAbort : EHScopeStack::Cleanup { 957 llvm::GlobalVariable *Guard; 958 CallGuardAbort(llvm::GlobalVariable *Guard) : Guard(Guard) {} 959 960 void Emit(CodeGenFunction &CGF, Flags flags) { 961 CGF.Builder.CreateCall(getGuardAbortFn(CGF.CGM, Guard->getType()), Guard) 962 ->setDoesNotThrow(); 963 } 964 }; 965} 966 967/// The ARM code here follows the Itanium code closely enough that we 968/// just special-case it at particular places. 969void ItaniumCXXABI::EmitGuardedInit(CodeGenFunction &CGF, 970 const VarDecl &D, 971 llvm::GlobalVariable *var, 972 bool shouldPerformInit) { 973 CGBuilderTy &Builder = CGF.Builder; 974 975 // We only need to use thread-safe statics for local variables; 976 // global initialization is always single-threaded. 977 bool threadsafe = 978 (getContext().getLangOpts().ThreadsafeStatics && D.isLocalVarDecl()); 979 980 // If we have a global variable with internal linkage and thread-safe statics 981 // are disabled, we can just let the guard variable be of type i8. 982 bool useInt8GuardVariable = !threadsafe && var->hasInternalLinkage(); 983 984 llvm::IntegerType *guardTy; 985 if (useInt8GuardVariable) { 986 guardTy = CGF.Int8Ty; 987 } else { 988 // Guard variables are 64 bits in the generic ABI and 32 bits on ARM. 989 guardTy = (IsARM ? CGF.Int32Ty : CGF.Int64Ty); 990 } 991 llvm::PointerType *guardPtrTy = guardTy->getPointerTo(); 992 993 // Create the guard variable if we don't already have it (as we 994 // might if we're double-emitting this function body). 995 llvm::GlobalVariable *guard = CGM.getStaticLocalDeclGuardAddress(&D); 996 if (!guard) { 997 // Mangle the name for the guard. 998 SmallString<256> guardName; 999 { 1000 llvm::raw_svector_ostream out(guardName); 1001 getMangleContext().mangleItaniumGuardVariable(&D, out); 1002 out.flush(); 1003 } 1004 1005 // Create the guard variable with a zero-initializer. 1006 // Just absorb linkage and visibility from the guarded variable. 1007 guard = new llvm::GlobalVariable(CGM.getModule(), guardTy, 1008 false, var->getLinkage(), 1009 llvm::ConstantInt::get(guardTy, 0), 1010 guardName.str()); 1011 guard->setVisibility(var->getVisibility()); 1012 1013 CGM.setStaticLocalDeclGuardAddress(&D, guard); 1014 } 1015 1016 // Test whether the variable has completed initialization. 1017 llvm::Value *isInitialized; 1018 1019 // ARM C++ ABI 3.2.3.1: 1020 // To support the potential use of initialization guard variables 1021 // as semaphores that are the target of ARM SWP and LDREX/STREX 1022 // synchronizing instructions we define a static initialization 1023 // guard variable to be a 4-byte aligned, 4- byte word with the 1024 // following inline access protocol. 1025 // #define INITIALIZED 1 1026 // if ((obj_guard & INITIALIZED) != INITIALIZED) { 1027 // if (__cxa_guard_acquire(&obj_guard)) 1028 // ... 1029 // } 1030 if (IsARM && !useInt8GuardVariable) { 1031 llvm::Value *V = Builder.CreateLoad(guard); 1032 V = Builder.CreateAnd(V, Builder.getInt32(1)); 1033 isInitialized = Builder.CreateIsNull(V, "guard.uninitialized"); 1034 1035 // Itanium C++ ABI 3.3.2: 1036 // The following is pseudo-code showing how these functions can be used: 1037 // if (obj_guard.first_byte == 0) { 1038 // if ( __cxa_guard_acquire (&obj_guard) ) { 1039 // try { 1040 // ... initialize the object ...; 1041 // } catch (...) { 1042 // __cxa_guard_abort (&obj_guard); 1043 // throw; 1044 // } 1045 // ... queue object destructor with __cxa_atexit() ...; 1046 // __cxa_guard_release (&obj_guard); 1047 // } 1048 // } 1049 } else { 1050 // Load the first byte of the guard variable. 1051 llvm::LoadInst *LI = 1052 Builder.CreateLoad(Builder.CreateBitCast(guard, CGM.Int8PtrTy)); 1053 LI->setAlignment(1); 1054 1055 // Itanium ABI: 1056 // An implementation supporting thread-safety on multiprocessor 1057 // systems must also guarantee that references to the initialized 1058 // object do not occur before the load of the initialization flag. 1059 // 1060 // In LLVM, we do this by marking the load Acquire. 1061 if (threadsafe) 1062 LI->setAtomic(llvm::Acquire); 1063 1064 isInitialized = Builder.CreateIsNull(LI, "guard.uninitialized"); 1065 } 1066 1067 llvm::BasicBlock *InitCheckBlock = CGF.createBasicBlock("init.check"); 1068 llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end"); 1069 1070 // Check if the first byte of the guard variable is zero. 1071 Builder.CreateCondBr(isInitialized, InitCheckBlock, EndBlock); 1072 1073 CGF.EmitBlock(InitCheckBlock); 1074 1075 // Variables used when coping with thread-safe statics and exceptions. 1076 if (threadsafe) { 1077 // Call __cxa_guard_acquire. 1078 llvm::Value *V 1079 = Builder.CreateCall(getGuardAcquireFn(CGM, guardPtrTy), guard); 1080 1081 llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init"); 1082 1083 Builder.CreateCondBr(Builder.CreateIsNotNull(V, "tobool"), 1084 InitBlock, EndBlock); 1085 1086 // Call __cxa_guard_abort along the exceptional edge. 1087 CGF.EHStack.pushCleanup<CallGuardAbort>(EHCleanup, guard); 1088 1089 CGF.EmitBlock(InitBlock); 1090 } 1091 1092 // Emit the initializer and add a global destructor if appropriate. 1093 CGF.EmitCXXGlobalVarDeclInit(D, var, shouldPerformInit); 1094 1095 if (threadsafe) { 1096 // Pop the guard-abort cleanup if we pushed one. 1097 CGF.PopCleanupBlock(); 1098 1099 // Call __cxa_guard_release. This cannot throw. 1100 Builder.CreateCall(getGuardReleaseFn(CGM, guardPtrTy), guard); 1101 } else { 1102 Builder.CreateStore(llvm::ConstantInt::get(guardTy, 1), guard); 1103 } 1104 1105 CGF.EmitBlock(EndBlock); 1106} 1107 1108/// Register a global destructor using __cxa_atexit. 1109static void emitGlobalDtorWithCXAAtExit(CodeGenFunction &CGF, 1110 llvm::Constant *dtor, 1111 llvm::Constant *addr) { 1112 // We're assuming that the destructor function is something we can 1113 // reasonably call with the default CC. Go ahead and cast it to the 1114 // right prototype. 1115 llvm::Type *dtorTy = 1116 llvm::FunctionType::get(CGF.VoidTy, CGF.Int8PtrTy, false)->getPointerTo(); 1117 1118 // extern "C" int __cxa_atexit(void (*f)(void *), void *p, void *d); 1119 llvm::Type *paramTys[] = { dtorTy, CGF.Int8PtrTy, CGF.Int8PtrTy }; 1120 llvm::FunctionType *atexitTy = 1121 llvm::FunctionType::get(CGF.IntTy, paramTys, false); 1122 1123 // Fetch the actual function. 1124 llvm::Constant *atexit = 1125 CGF.CGM.CreateRuntimeFunction(atexitTy, "__cxa_atexit"); 1126 if (llvm::Function *fn = dyn_cast<llvm::Function>(atexit)) 1127 fn->setDoesNotThrow(); 1128 1129 // Create a variable that binds the atexit to this shared object. 1130 llvm::Constant *handle = 1131 CGF.CGM.CreateRuntimeVariable(CGF.Int8Ty, "__dso_handle"); 1132 1133 llvm::Value *args[] = { 1134 llvm::ConstantExpr::getBitCast(dtor, dtorTy), 1135 llvm::ConstantExpr::getBitCast(addr, CGF.Int8PtrTy), 1136 handle 1137 }; 1138 CGF.Builder.CreateCall(atexit, args)->setDoesNotThrow(); 1139} 1140 1141/// Register a global destructor as best as we know how. 1142void ItaniumCXXABI::registerGlobalDtor(CodeGenFunction &CGF, 1143 llvm::Constant *dtor, 1144 llvm::Constant *addr) { 1145 // Use __cxa_atexit if available. 1146 if (CGM.getCodeGenOpts().CXAAtExit) { 1147 return emitGlobalDtorWithCXAAtExit(CGF, dtor, addr); 1148 } 1149 1150 // In Apple kexts, we want to add a global destructor entry. 1151 // FIXME: shouldn't this be guarded by some variable? 1152 if (CGM.getContext().getLangOpts().AppleKext) { 1153 // Generate a global destructor entry. 1154 return CGM.AddCXXDtorEntry(dtor, addr); 1155 } 1156 1157 CGF.registerGlobalDtorWithAtExit(dtor, addr); 1158} 1159 1160/// Generate and emit virtual tables for the given class. 1161void ItaniumCXXABI::EmitVTables(const CXXRecordDecl *Class) { 1162 CGM.getVTables().GenerateClassData(CGM.getVTableLinkage(Class), Class); 1163} 1164