1 //===--- CGBlocks.cpp - Emit LLVM Code for declarations -------------------===// 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 contains code to emit blocks. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "CGBlocks.h" 15 #include "CGDebugInfo.h" 16 #include "CGObjCRuntime.h" 17 #include "CodeGenFunction.h" 18 #include "CodeGenModule.h" 19 #include "clang/AST/DeclObjC.h" 20 #include "llvm/ADT/SmallSet.h" 21 #include "llvm/IR/CallSite.h" 22 #include "llvm/IR/DataLayout.h" 23 #include "llvm/IR/Module.h" 24 #include <algorithm> 25 #include <cstdio> 26 27 using namespace clang; 28 using namespace CodeGen; 29 30 CGBlockInfo::CGBlockInfo(const BlockDecl *block, StringRef name) 31 : Name(name), CXXThisIndex(0), CanBeGlobal(false), NeedsCopyDispose(false), 32 HasCXXObject(false), UsesStret(false), HasCapturedVariableLayout(false), 33 StructureType(nullptr), Block(block), 34 DominatingIP(nullptr) { 35 36 // Skip asm prefix, if any. 'name' is usually taken directly from 37 // the mangled name of the enclosing function. 38 if (!name.empty() && name[0] == '\01') 39 name = name.substr(1); 40 } 41 42 // Anchor the vtable to this translation unit. 43 CodeGenModule::ByrefHelpers::~ByrefHelpers() {} 44 45 /// Build the given block as a global block. 46 static llvm::Constant *buildGlobalBlock(CodeGenModule &CGM, 47 const CGBlockInfo &blockInfo, 48 llvm::Constant *blockFn); 49 50 /// Build the helper function to copy a block. 51 static llvm::Constant *buildCopyHelper(CodeGenModule &CGM, 52 const CGBlockInfo &blockInfo) { 53 return CodeGenFunction(CGM).GenerateCopyHelperFunction(blockInfo); 54 } 55 56 /// Build the helper function to dispose of a block. 57 static llvm::Constant *buildDisposeHelper(CodeGenModule &CGM, 58 const CGBlockInfo &blockInfo) { 59 return CodeGenFunction(CGM).GenerateDestroyHelperFunction(blockInfo); 60 } 61 62 /// buildBlockDescriptor - Build the block descriptor meta-data for a block. 63 /// buildBlockDescriptor is accessed from 5th field of the Block_literal 64 /// meta-data and contains stationary information about the block literal. 65 /// Its definition will have 4 (or optinally 6) words. 66 /// \code 67 /// struct Block_descriptor { 68 /// unsigned long reserved; 69 /// unsigned long size; // size of Block_literal metadata in bytes. 70 /// void *copy_func_helper_decl; // optional copy helper. 71 /// void *destroy_func_decl; // optioanl destructor helper. 72 /// void *block_method_encoding_address; // @encode for block literal signature. 73 /// void *block_layout_info; // encoding of captured block variables. 74 /// }; 75 /// \endcode 76 static llvm::Constant *buildBlockDescriptor(CodeGenModule &CGM, 77 const CGBlockInfo &blockInfo) { 78 ASTContext &C = CGM.getContext(); 79 80 llvm::Type *ulong = CGM.getTypes().ConvertType(C.UnsignedLongTy); 81 llvm::Type *i8p = NULL; 82 if (CGM.getLangOpts().OpenCL) 83 i8p = 84 llvm::Type::getInt8PtrTy( 85 CGM.getLLVMContext(), C.getTargetAddressSpace(LangAS::opencl_constant)); 86 else 87 i8p = CGM.getTypes().ConvertType(C.VoidPtrTy); 88 89 SmallVector<llvm::Constant*, 6> elements; 90 91 // reserved 92 elements.push_back(llvm::ConstantInt::get(ulong, 0)); 93 94 // Size 95 // FIXME: What is the right way to say this doesn't fit? We should give 96 // a user diagnostic in that case. Better fix would be to change the 97 // API to size_t. 98 elements.push_back(llvm::ConstantInt::get(ulong, 99 blockInfo.BlockSize.getQuantity())); 100 101 // Optional copy/dispose helpers. 102 if (blockInfo.NeedsCopyDispose) { 103 // copy_func_helper_decl 104 elements.push_back(buildCopyHelper(CGM, blockInfo)); 105 106 // destroy_func_decl 107 elements.push_back(buildDisposeHelper(CGM, blockInfo)); 108 } 109 110 // Signature. Mandatory ObjC-style method descriptor @encode sequence. 111 std::string typeAtEncoding = 112 CGM.getContext().getObjCEncodingForBlock(blockInfo.getBlockExpr()); 113 elements.push_back(llvm::ConstantExpr::getBitCast( 114 CGM.GetAddrOfConstantCString(typeAtEncoding), i8p)); 115 116 // GC layout. 117 if (C.getLangOpts().ObjC1) { 118 if (CGM.getLangOpts().getGC() != LangOptions::NonGC) 119 elements.push_back(CGM.getObjCRuntime().BuildGCBlockLayout(CGM, blockInfo)); 120 else 121 elements.push_back(CGM.getObjCRuntime().BuildRCBlockLayout(CGM, blockInfo)); 122 } 123 else 124 elements.push_back(llvm::Constant::getNullValue(i8p)); 125 126 llvm::Constant *init = llvm::ConstantStruct::getAnon(elements); 127 128 llvm::GlobalVariable *global = 129 new llvm::GlobalVariable(CGM.getModule(), init->getType(), true, 130 llvm::GlobalValue::InternalLinkage, 131 init, "__block_descriptor_tmp"); 132 133 return llvm::ConstantExpr::getBitCast(global, CGM.getBlockDescriptorType()); 134 } 135 136 /* 137 Purely notional variadic template describing the layout of a block. 138 139 template <class _ResultType, class... _ParamTypes, class... _CaptureTypes> 140 struct Block_literal { 141 /// Initialized to one of: 142 /// extern void *_NSConcreteStackBlock[]; 143 /// extern void *_NSConcreteGlobalBlock[]; 144 /// 145 /// In theory, we could start one off malloc'ed by setting 146 /// BLOCK_NEEDS_FREE, giving it a refcount of 1, and using 147 /// this isa: 148 /// extern void *_NSConcreteMallocBlock[]; 149 struct objc_class *isa; 150 151 /// These are the flags (with corresponding bit number) that the 152 /// compiler is actually supposed to know about. 153 /// 25. BLOCK_HAS_COPY_DISPOSE - indicates that the block 154 /// descriptor provides copy and dispose helper functions 155 /// 26. BLOCK_HAS_CXX_OBJ - indicates that there's a captured 156 /// object with a nontrivial destructor or copy constructor 157 /// 28. BLOCK_IS_GLOBAL - indicates that the block is allocated 158 /// as global memory 159 /// 29. BLOCK_USE_STRET - indicates that the block function 160 /// uses stret, which objc_msgSend needs to know about 161 /// 30. BLOCK_HAS_SIGNATURE - indicates that the block has an 162 /// @encoded signature string 163 /// And we're not supposed to manipulate these: 164 /// 24. BLOCK_NEEDS_FREE - indicates that the block has been moved 165 /// to malloc'ed memory 166 /// 27. BLOCK_IS_GC - indicates that the block has been moved to 167 /// to GC-allocated memory 168 /// Additionally, the bottom 16 bits are a reference count which 169 /// should be zero on the stack. 170 int flags; 171 172 /// Reserved; should be zero-initialized. 173 int reserved; 174 175 /// Function pointer generated from block literal. 176 _ResultType (*invoke)(Block_literal *, _ParamTypes...); 177 178 /// Block description metadata generated from block literal. 179 struct Block_descriptor *block_descriptor; 180 181 /// Captured values follow. 182 _CapturesTypes captures...; 183 }; 184 */ 185 186 /// The number of fields in a block header. 187 const unsigned BlockHeaderSize = 5; 188 189 namespace { 190 /// A chunk of data that we actually have to capture in the block. 191 struct BlockLayoutChunk { 192 CharUnits Alignment; 193 CharUnits Size; 194 Qualifiers::ObjCLifetime Lifetime; 195 const BlockDecl::Capture *Capture; // null for 'this' 196 llvm::Type *Type; 197 198 BlockLayoutChunk(CharUnits align, CharUnits size, 199 Qualifiers::ObjCLifetime lifetime, 200 const BlockDecl::Capture *capture, 201 llvm::Type *type) 202 : Alignment(align), Size(size), Lifetime(lifetime), 203 Capture(capture), Type(type) {} 204 205 /// Tell the block info that this chunk has the given field index. 206 void setIndex(CGBlockInfo &info, unsigned index) { 207 if (!Capture) 208 info.CXXThisIndex = index; 209 else 210 info.Captures[Capture->getVariable()] 211 = CGBlockInfo::Capture::makeIndex(index); 212 } 213 }; 214 215 /// Order by 1) all __strong together 2) next, all byfref together 3) next, 216 /// all __weak together. Preserve descending alignment in all situations. 217 bool operator<(const BlockLayoutChunk &left, const BlockLayoutChunk &right) { 218 CharUnits LeftValue, RightValue; 219 bool LeftByref = left.Capture ? left.Capture->isByRef() : false; 220 bool RightByref = right.Capture ? right.Capture->isByRef() : false; 221 222 if (left.Lifetime == Qualifiers::OCL_Strong && 223 left.Alignment >= right.Alignment) 224 LeftValue = CharUnits::fromQuantity(64); 225 else if (LeftByref && left.Alignment >= right.Alignment) 226 LeftValue = CharUnits::fromQuantity(32); 227 else if (left.Lifetime == Qualifiers::OCL_Weak && 228 left.Alignment >= right.Alignment) 229 LeftValue = CharUnits::fromQuantity(16); 230 else 231 LeftValue = left.Alignment; 232 if (right.Lifetime == Qualifiers::OCL_Strong && 233 right.Alignment >= left.Alignment) 234 RightValue = CharUnits::fromQuantity(64); 235 else if (RightByref && right.Alignment >= left.Alignment) 236 RightValue = CharUnits::fromQuantity(32); 237 else if (right.Lifetime == Qualifiers::OCL_Weak && 238 right.Alignment >= left.Alignment) 239 RightValue = CharUnits::fromQuantity(16); 240 else 241 RightValue = right.Alignment; 242 243 return LeftValue > RightValue; 244 } 245 } 246 247 /// Determines if the given type is safe for constant capture in C++. 248 static bool isSafeForCXXConstantCapture(QualType type) { 249 const RecordType *recordType = 250 type->getBaseElementTypeUnsafe()->getAs<RecordType>(); 251 252 // Only records can be unsafe. 253 if (!recordType) return true; 254 255 const auto *record = cast<CXXRecordDecl>(recordType->getDecl()); 256 257 // Maintain semantics for classes with non-trivial dtors or copy ctors. 258 if (!record->hasTrivialDestructor()) return false; 259 if (record->hasNonTrivialCopyConstructor()) return false; 260 261 // Otherwise, we just have to make sure there aren't any mutable 262 // fields that might have changed since initialization. 263 return !record->hasMutableFields(); 264 } 265 266 /// It is illegal to modify a const object after initialization. 267 /// Therefore, if a const object has a constant initializer, we don't 268 /// actually need to keep storage for it in the block; we'll just 269 /// rematerialize it at the start of the block function. This is 270 /// acceptable because we make no promises about address stability of 271 /// captured variables. 272 static llvm::Constant *tryCaptureAsConstant(CodeGenModule &CGM, 273 CodeGenFunction *CGF, 274 const VarDecl *var) { 275 QualType type = var->getType(); 276 277 // We can only do this if the variable is const. 278 if (!type.isConstQualified()) return nullptr; 279 280 // Furthermore, in C++ we have to worry about mutable fields: 281 // C++ [dcl.type.cv]p4: 282 // Except that any class member declared mutable can be 283 // modified, any attempt to modify a const object during its 284 // lifetime results in undefined behavior. 285 if (CGM.getLangOpts().CPlusPlus && !isSafeForCXXConstantCapture(type)) 286 return nullptr; 287 288 // If the variable doesn't have any initializer (shouldn't this be 289 // invalid?), it's not clear what we should do. Maybe capture as 290 // zero? 291 const Expr *init = var->getInit(); 292 if (!init) return nullptr; 293 294 return CGM.EmitConstantInit(*var, CGF); 295 } 296 297 /// Get the low bit of a nonzero character count. This is the 298 /// alignment of the nth byte if the 0th byte is universally aligned. 299 static CharUnits getLowBit(CharUnits v) { 300 return CharUnits::fromQuantity(v.getQuantity() & (~v.getQuantity() + 1)); 301 } 302 303 static void initializeForBlockHeader(CodeGenModule &CGM, CGBlockInfo &info, 304 SmallVectorImpl<llvm::Type*> &elementTypes) { 305 ASTContext &C = CGM.getContext(); 306 307 // The header is basically a 'struct { void *; int; int; void *; void *; }'. 308 CharUnits ptrSize, ptrAlign, intSize, intAlign; 309 std::tie(ptrSize, ptrAlign) = C.getTypeInfoInChars(C.VoidPtrTy); 310 std::tie(intSize, intAlign) = C.getTypeInfoInChars(C.IntTy); 311 312 // Are there crazy embedded platforms where this isn't true? 313 assert(intSize <= ptrSize && "layout assumptions horribly violated"); 314 315 CharUnits headerSize = ptrSize; 316 if (2 * intSize < ptrAlign) headerSize += ptrSize; 317 else headerSize += 2 * intSize; 318 headerSize += 2 * ptrSize; 319 320 info.BlockAlign = ptrAlign; 321 info.BlockSize = headerSize; 322 323 assert(elementTypes.empty()); 324 llvm::Type *i8p = CGM.getTypes().ConvertType(C.VoidPtrTy); 325 llvm::Type *intTy = CGM.getTypes().ConvertType(C.IntTy); 326 elementTypes.push_back(i8p); 327 elementTypes.push_back(intTy); 328 elementTypes.push_back(intTy); 329 elementTypes.push_back(i8p); 330 elementTypes.push_back(CGM.getBlockDescriptorType()); 331 332 assert(elementTypes.size() == BlockHeaderSize); 333 } 334 335 /// Compute the layout of the given block. Attempts to lay the block 336 /// out with minimal space requirements. 337 static void computeBlockInfo(CodeGenModule &CGM, CodeGenFunction *CGF, 338 CGBlockInfo &info) { 339 ASTContext &C = CGM.getContext(); 340 const BlockDecl *block = info.getBlockDecl(); 341 342 SmallVector<llvm::Type*, 8> elementTypes; 343 initializeForBlockHeader(CGM, info, elementTypes); 344 345 if (!block->hasCaptures()) { 346 info.StructureType = 347 llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true); 348 info.CanBeGlobal = true; 349 return; 350 } 351 else if (C.getLangOpts().ObjC1 && 352 CGM.getLangOpts().getGC() == LangOptions::NonGC) 353 info.HasCapturedVariableLayout = true; 354 355 // Collect the layout chunks. 356 SmallVector<BlockLayoutChunk, 16> layout; 357 layout.reserve(block->capturesCXXThis() + 358 (block->capture_end() - block->capture_begin())); 359 360 CharUnits maxFieldAlign; 361 362 // First, 'this'. 363 if (block->capturesCXXThis()) { 364 assert(CGF && CGF->CurFuncDecl && isa<CXXMethodDecl>(CGF->CurFuncDecl) && 365 "Can't capture 'this' outside a method"); 366 QualType thisType = cast<CXXMethodDecl>(CGF->CurFuncDecl)->getThisType(C); 367 368 llvm::Type *llvmType = CGM.getTypes().ConvertType(thisType); 369 std::pair<CharUnits,CharUnits> tinfo 370 = CGM.getContext().getTypeInfoInChars(thisType); 371 maxFieldAlign = std::max(maxFieldAlign, tinfo.second); 372 373 layout.push_back(BlockLayoutChunk(tinfo.second, tinfo.first, 374 Qualifiers::OCL_None, 375 nullptr, llvmType)); 376 } 377 378 // Next, all the block captures. 379 for (const auto &CI : block->captures()) { 380 const VarDecl *variable = CI.getVariable(); 381 382 if (CI.isByRef()) { 383 // We have to copy/dispose of the __block reference. 384 info.NeedsCopyDispose = true; 385 386 // Just use void* instead of a pointer to the byref type. 387 QualType byRefPtrTy = C.VoidPtrTy; 388 389 llvm::Type *llvmType = CGM.getTypes().ConvertType(byRefPtrTy); 390 std::pair<CharUnits,CharUnits> tinfo 391 = CGM.getContext().getTypeInfoInChars(byRefPtrTy); 392 maxFieldAlign = std::max(maxFieldAlign, tinfo.second); 393 394 layout.push_back(BlockLayoutChunk(tinfo.second, tinfo.first, 395 Qualifiers::OCL_None, &CI, llvmType)); 396 continue; 397 } 398 399 // Otherwise, build a layout chunk with the size and alignment of 400 // the declaration. 401 if (llvm::Constant *constant = tryCaptureAsConstant(CGM, CGF, variable)) { 402 info.Captures[variable] = CGBlockInfo::Capture::makeConstant(constant); 403 continue; 404 } 405 406 // If we have a lifetime qualifier, honor it for capture purposes. 407 // That includes *not* copying it if it's __unsafe_unretained. 408 Qualifiers::ObjCLifetime lifetime = 409 variable->getType().getObjCLifetime(); 410 if (lifetime) { 411 switch (lifetime) { 412 case Qualifiers::OCL_None: llvm_unreachable("impossible"); 413 case Qualifiers::OCL_ExplicitNone: 414 case Qualifiers::OCL_Autoreleasing: 415 break; 416 417 case Qualifiers::OCL_Strong: 418 case Qualifiers::OCL_Weak: 419 info.NeedsCopyDispose = true; 420 } 421 422 // Block pointers require copy/dispose. So do Objective-C pointers. 423 } else if (variable->getType()->isObjCRetainableType()) { 424 info.NeedsCopyDispose = true; 425 // used for mrr below. 426 lifetime = Qualifiers::OCL_Strong; 427 428 // So do types that require non-trivial copy construction. 429 } else if (CI.hasCopyExpr()) { 430 info.NeedsCopyDispose = true; 431 info.HasCXXObject = true; 432 433 // And so do types with destructors. 434 } else if (CGM.getLangOpts().CPlusPlus) { 435 if (const CXXRecordDecl *record = 436 variable->getType()->getAsCXXRecordDecl()) { 437 if (!record->hasTrivialDestructor()) { 438 info.HasCXXObject = true; 439 info.NeedsCopyDispose = true; 440 } 441 } 442 } 443 444 QualType VT = variable->getType(); 445 CharUnits size = C.getTypeSizeInChars(VT); 446 CharUnits align = C.getDeclAlign(variable); 447 448 maxFieldAlign = std::max(maxFieldAlign, align); 449 450 llvm::Type *llvmType = 451 CGM.getTypes().ConvertTypeForMem(VT); 452 453 layout.push_back(BlockLayoutChunk(align, size, lifetime, &CI, llvmType)); 454 } 455 456 // If that was everything, we're done here. 457 if (layout.empty()) { 458 info.StructureType = 459 llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true); 460 info.CanBeGlobal = true; 461 return; 462 } 463 464 // Sort the layout by alignment. We have to use a stable sort here 465 // to get reproducible results. There should probably be an 466 // llvm::array_pod_stable_sort. 467 std::stable_sort(layout.begin(), layout.end()); 468 469 // Needed for blocks layout info. 470 info.BlockHeaderForcedGapOffset = info.BlockSize; 471 info.BlockHeaderForcedGapSize = CharUnits::Zero(); 472 473 CharUnits &blockSize = info.BlockSize; 474 info.BlockAlign = std::max(maxFieldAlign, info.BlockAlign); 475 476 // Assuming that the first byte in the header is maximally aligned, 477 // get the alignment of the first byte following the header. 478 CharUnits endAlign = getLowBit(blockSize); 479 480 // If the end of the header isn't satisfactorily aligned for the 481 // maximum thing, look for things that are okay with the header-end 482 // alignment, and keep appending them until we get something that's 483 // aligned right. This algorithm is only guaranteed optimal if 484 // that condition is satisfied at some point; otherwise we can get 485 // things like: 486 // header // next byte has alignment 4 487 // something_with_size_5; // next byte has alignment 1 488 // something_with_alignment_8; 489 // which has 7 bytes of padding, as opposed to the naive solution 490 // which might have less (?). 491 if (endAlign < maxFieldAlign) { 492 SmallVectorImpl<BlockLayoutChunk>::iterator 493 li = layout.begin() + 1, le = layout.end(); 494 495 // Look for something that the header end is already 496 // satisfactorily aligned for. 497 for (; li != le && endAlign < li->Alignment; ++li) 498 ; 499 500 // If we found something that's naturally aligned for the end of 501 // the header, keep adding things... 502 if (li != le) { 503 SmallVectorImpl<BlockLayoutChunk>::iterator first = li; 504 for (; li != le; ++li) { 505 assert(endAlign >= li->Alignment); 506 507 li->setIndex(info, elementTypes.size()); 508 elementTypes.push_back(li->Type); 509 blockSize += li->Size; 510 endAlign = getLowBit(blockSize); 511 512 // ...until we get to the alignment of the maximum field. 513 if (endAlign >= maxFieldAlign) { 514 if (li == first) { 515 // No user field was appended. So, a gap was added. 516 // Save total gap size for use in block layout bit map. 517 info.BlockHeaderForcedGapSize = li->Size; 518 } 519 break; 520 } 521 } 522 // Don't re-append everything we just appended. 523 layout.erase(first, li); 524 } 525 } 526 527 assert(endAlign == getLowBit(blockSize)); 528 529 // At this point, we just have to add padding if the end align still 530 // isn't aligned right. 531 if (endAlign < maxFieldAlign) { 532 CharUnits newBlockSize = blockSize.RoundUpToAlignment(maxFieldAlign); 533 CharUnits padding = newBlockSize - blockSize; 534 535 elementTypes.push_back(llvm::ArrayType::get(CGM.Int8Ty, 536 padding.getQuantity())); 537 blockSize = newBlockSize; 538 endAlign = getLowBit(blockSize); // might be > maxFieldAlign 539 } 540 541 assert(endAlign >= maxFieldAlign); 542 assert(endAlign == getLowBit(blockSize)); 543 // Slam everything else on now. This works because they have 544 // strictly decreasing alignment and we expect that size is always a 545 // multiple of alignment. 546 for (SmallVectorImpl<BlockLayoutChunk>::iterator 547 li = layout.begin(), le = layout.end(); li != le; ++li) { 548 if (endAlign < li->Alignment) { 549 // size may not be multiple of alignment. This can only happen with 550 // an over-aligned variable. We will be adding a padding field to 551 // make the size be multiple of alignment. 552 CharUnits padding = li->Alignment - endAlign; 553 elementTypes.push_back(llvm::ArrayType::get(CGM.Int8Ty, 554 padding.getQuantity())); 555 blockSize += padding; 556 endAlign = getLowBit(blockSize); 557 } 558 assert(endAlign >= li->Alignment); 559 li->setIndex(info, elementTypes.size()); 560 elementTypes.push_back(li->Type); 561 blockSize += li->Size; 562 endAlign = getLowBit(blockSize); 563 } 564 565 info.StructureType = 566 llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true); 567 } 568 569 /// Enter the scope of a block. This should be run at the entrance to 570 /// a full-expression so that the block's cleanups are pushed at the 571 /// right place in the stack. 572 static void enterBlockScope(CodeGenFunction &CGF, BlockDecl *block) { 573 assert(CGF.HaveInsertPoint()); 574 575 // Allocate the block info and place it at the head of the list. 576 CGBlockInfo &blockInfo = 577 *new CGBlockInfo(block, CGF.CurFn->getName()); 578 blockInfo.NextBlockInfo = CGF.FirstBlockInfo; 579 CGF.FirstBlockInfo = &blockInfo; 580 581 // Compute information about the layout, etc., of this block, 582 // pushing cleanups as necessary. 583 computeBlockInfo(CGF.CGM, &CGF, blockInfo); 584 585 // Nothing else to do if it can be global. 586 if (blockInfo.CanBeGlobal) return; 587 588 // Make the allocation for the block. 589 blockInfo.Address = 590 CGF.CreateTempAlloca(blockInfo.StructureType, "block"); 591 blockInfo.Address->setAlignment(blockInfo.BlockAlign.getQuantity()); 592 593 // If there are cleanups to emit, enter them (but inactive). 594 if (!blockInfo.NeedsCopyDispose) return; 595 596 // Walk through the captures (in order) and find the ones not 597 // captured by constant. 598 for (const auto &CI : block->captures()) { 599 // Ignore __block captures; there's nothing special in the 600 // on-stack block that we need to do for them. 601 if (CI.isByRef()) continue; 602 603 // Ignore variables that are constant-captured. 604 const VarDecl *variable = CI.getVariable(); 605 CGBlockInfo::Capture &capture = blockInfo.getCapture(variable); 606 if (capture.isConstant()) continue; 607 608 // Ignore objects that aren't destructed. 609 QualType::DestructionKind dtorKind = 610 variable->getType().isDestructedType(); 611 if (dtorKind == QualType::DK_none) continue; 612 613 CodeGenFunction::Destroyer *destroyer; 614 615 // Block captures count as local values and have imprecise semantics. 616 // They also can't be arrays, so need to worry about that. 617 if (dtorKind == QualType::DK_objc_strong_lifetime) { 618 destroyer = CodeGenFunction::destroyARCStrongImprecise; 619 } else { 620 destroyer = CGF.getDestroyer(dtorKind); 621 } 622 623 // GEP down to the address. 624 llvm::Value *addr = CGF.Builder.CreateStructGEP(blockInfo.Address, 625 capture.getIndex()); 626 627 // We can use that GEP as the dominating IP. 628 if (!blockInfo.DominatingIP) 629 blockInfo.DominatingIP = cast<llvm::Instruction>(addr); 630 631 CleanupKind cleanupKind = InactiveNormalCleanup; 632 bool useArrayEHCleanup = CGF.needsEHCleanup(dtorKind); 633 if (useArrayEHCleanup) 634 cleanupKind = InactiveNormalAndEHCleanup; 635 636 CGF.pushDestroy(cleanupKind, addr, variable->getType(), 637 destroyer, useArrayEHCleanup); 638 639 // Remember where that cleanup was. 640 capture.setCleanup(CGF.EHStack.stable_begin()); 641 } 642 } 643 644 /// Enter a full-expression with a non-trivial number of objects to 645 /// clean up. This is in this file because, at the moment, the only 646 /// kind of cleanup object is a BlockDecl*. 647 void CodeGenFunction::enterNonTrivialFullExpression(const ExprWithCleanups *E) { 648 assert(E->getNumObjects() != 0); 649 ArrayRef<ExprWithCleanups::CleanupObject> cleanups = E->getObjects(); 650 for (ArrayRef<ExprWithCleanups::CleanupObject>::iterator 651 i = cleanups.begin(), e = cleanups.end(); i != e; ++i) { 652 enterBlockScope(*this, *i); 653 } 654 } 655 656 /// Find the layout for the given block in a linked list and remove it. 657 static CGBlockInfo *findAndRemoveBlockInfo(CGBlockInfo **head, 658 const BlockDecl *block) { 659 while (true) { 660 assert(head && *head); 661 CGBlockInfo *cur = *head; 662 663 // If this is the block we're looking for, splice it out of the list. 664 if (cur->getBlockDecl() == block) { 665 *head = cur->NextBlockInfo; 666 return cur; 667 } 668 669 head = &cur->NextBlockInfo; 670 } 671 } 672 673 /// Destroy a chain of block layouts. 674 void CodeGenFunction::destroyBlockInfos(CGBlockInfo *head) { 675 assert(head && "destroying an empty chain"); 676 do { 677 CGBlockInfo *cur = head; 678 head = cur->NextBlockInfo; 679 delete cur; 680 } while (head != nullptr); 681 } 682 683 /// Emit a block literal expression in the current function. 684 llvm::Value *CodeGenFunction::EmitBlockLiteral(const BlockExpr *blockExpr) { 685 // If the block has no captures, we won't have a pre-computed 686 // layout for it. 687 if (!blockExpr->getBlockDecl()->hasCaptures()) { 688 CGBlockInfo blockInfo(blockExpr->getBlockDecl(), CurFn->getName()); 689 computeBlockInfo(CGM, this, blockInfo); 690 blockInfo.BlockExpression = blockExpr; 691 return EmitBlockLiteral(blockInfo); 692 } 693 694 // Find the block info for this block and take ownership of it. 695 std::unique_ptr<CGBlockInfo> blockInfo; 696 blockInfo.reset(findAndRemoveBlockInfo(&FirstBlockInfo, 697 blockExpr->getBlockDecl())); 698 699 blockInfo->BlockExpression = blockExpr; 700 return EmitBlockLiteral(*blockInfo); 701 } 702 703 llvm::Value *CodeGenFunction::EmitBlockLiteral(const CGBlockInfo &blockInfo) { 704 // Using the computed layout, generate the actual block function. 705 bool isLambdaConv = blockInfo.getBlockDecl()->isConversionFromLambda(); 706 llvm::Constant *blockFn 707 = CodeGenFunction(CGM, true).GenerateBlockFunction(CurGD, blockInfo, 708 LocalDeclMap, 709 isLambdaConv); 710 blockFn = llvm::ConstantExpr::getBitCast(blockFn, VoidPtrTy); 711 712 // If there is nothing to capture, we can emit this as a global block. 713 if (blockInfo.CanBeGlobal) 714 return buildGlobalBlock(CGM, blockInfo, blockFn); 715 716 // Otherwise, we have to emit this as a local block. 717 718 llvm::Constant *isa = CGM.getNSConcreteStackBlock(); 719 isa = llvm::ConstantExpr::getBitCast(isa, VoidPtrTy); 720 721 // Build the block descriptor. 722 llvm::Constant *descriptor = buildBlockDescriptor(CGM, blockInfo); 723 724 llvm::AllocaInst *blockAddr = blockInfo.Address; 725 assert(blockAddr && "block has no address!"); 726 727 // Compute the initial on-stack block flags. 728 BlockFlags flags = BLOCK_HAS_SIGNATURE; 729 if (blockInfo.HasCapturedVariableLayout) flags |= BLOCK_HAS_EXTENDED_LAYOUT; 730 if (blockInfo.NeedsCopyDispose) flags |= BLOCK_HAS_COPY_DISPOSE; 731 if (blockInfo.HasCXXObject) flags |= BLOCK_HAS_CXX_OBJ; 732 if (blockInfo.UsesStret) flags |= BLOCK_USE_STRET; 733 734 // Initialize the block literal. 735 Builder.CreateStore(isa, Builder.CreateStructGEP(blockAddr, 0, "block.isa")); 736 Builder.CreateStore(llvm::ConstantInt::get(IntTy, flags.getBitMask()), 737 Builder.CreateStructGEP(blockAddr, 1, "block.flags")); 738 Builder.CreateStore(llvm::ConstantInt::get(IntTy, 0), 739 Builder.CreateStructGEP(blockAddr, 2, "block.reserved")); 740 Builder.CreateStore(blockFn, Builder.CreateStructGEP(blockAddr, 3, 741 "block.invoke")); 742 Builder.CreateStore(descriptor, Builder.CreateStructGEP(blockAddr, 4, 743 "block.descriptor")); 744 745 // Finally, capture all the values into the block. 746 const BlockDecl *blockDecl = blockInfo.getBlockDecl(); 747 748 // First, 'this'. 749 if (blockDecl->capturesCXXThis()) { 750 llvm::Value *addr = Builder.CreateStructGEP(blockAddr, 751 blockInfo.CXXThisIndex, 752 "block.captured-this.addr"); 753 Builder.CreateStore(LoadCXXThis(), addr); 754 } 755 756 // Next, captured variables. 757 for (const auto &CI : blockDecl->captures()) { 758 const VarDecl *variable = CI.getVariable(); 759 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable); 760 761 // Ignore constant captures. 762 if (capture.isConstant()) continue; 763 764 QualType type = variable->getType(); 765 CharUnits align = getContext().getDeclAlign(variable); 766 767 // This will be a [[type]]*, except that a byref entry will just be 768 // an i8**. 769 llvm::Value *blockField = 770 Builder.CreateStructGEP(blockAddr, capture.getIndex(), 771 "block.captured"); 772 773 // Compute the address of the thing we're going to move into the 774 // block literal. 775 llvm::Value *src; 776 if (BlockInfo && CI.isNested()) { 777 // We need to use the capture from the enclosing block. 778 const CGBlockInfo::Capture &enclosingCapture = 779 BlockInfo->getCapture(variable); 780 781 // This is a [[type]]*, except that a byref entry wil just be an i8**. 782 src = Builder.CreateStructGEP(LoadBlockStruct(), 783 enclosingCapture.getIndex(), 784 "block.capture.addr"); 785 } else if (blockDecl->isConversionFromLambda()) { 786 // The lambda capture in a lambda's conversion-to-block-pointer is 787 // special; we'll simply emit it directly. 788 src = nullptr; 789 } else { 790 // Just look it up in the locals map, which will give us back a 791 // [[type]]*. If that doesn't work, do the more elaborate DRE 792 // emission. 793 src = LocalDeclMap.lookup(variable); 794 if (!src) { 795 DeclRefExpr declRef( 796 const_cast<VarDecl *>(variable), 797 /*RefersToEnclosingVariableOrCapture*/ CI.isNested(), type, 798 VK_LValue, SourceLocation()); 799 src = EmitDeclRefLValue(&declRef).getAddress(); 800 } 801 } 802 803 // For byrefs, we just write the pointer to the byref struct into 804 // the block field. There's no need to chase the forwarding 805 // pointer at this point, since we're building something that will 806 // live a shorter life than the stack byref anyway. 807 if (CI.isByRef()) { 808 // Get a void* that points to the byref struct. 809 if (CI.isNested()) 810 src = Builder.CreateAlignedLoad(src, align.getQuantity(), 811 "byref.capture"); 812 else 813 src = Builder.CreateBitCast(src, VoidPtrTy); 814 815 // Write that void* into the capture field. 816 Builder.CreateAlignedStore(src, blockField, align.getQuantity()); 817 818 // If we have a copy constructor, evaluate that into the block field. 819 } else if (const Expr *copyExpr = CI.getCopyExpr()) { 820 if (blockDecl->isConversionFromLambda()) { 821 // If we have a lambda conversion, emit the expression 822 // directly into the block instead. 823 AggValueSlot Slot = 824 AggValueSlot::forAddr(blockField, align, Qualifiers(), 825 AggValueSlot::IsDestructed, 826 AggValueSlot::DoesNotNeedGCBarriers, 827 AggValueSlot::IsNotAliased); 828 EmitAggExpr(copyExpr, Slot); 829 } else { 830 EmitSynthesizedCXXCopyCtor(blockField, src, copyExpr); 831 } 832 833 // If it's a reference variable, copy the reference into the block field. 834 } else if (type->isReferenceType()) { 835 llvm::Value *ref = 836 Builder.CreateAlignedLoad(src, align.getQuantity(), "ref.val"); 837 Builder.CreateAlignedStore(ref, blockField, align.getQuantity()); 838 839 // If this is an ARC __strong block-pointer variable, don't do a 840 // block copy. 841 // 842 // TODO: this can be generalized into the normal initialization logic: 843 // we should never need to do a block-copy when initializing a local 844 // variable, because the local variable's lifetime should be strictly 845 // contained within the stack block's. 846 } else if (type.getObjCLifetime() == Qualifiers::OCL_Strong && 847 type->isBlockPointerType()) { 848 // Load the block and do a simple retain. 849 LValue srcLV = MakeAddrLValue(src, type, align); 850 llvm::Value *value = EmitLoadOfScalar(srcLV, SourceLocation()); 851 value = EmitARCRetainNonBlock(value); 852 853 // Do a primitive store to the block field. 854 LValue destLV = MakeAddrLValue(blockField, type, align); 855 EmitStoreOfScalar(value, destLV, /*init*/ true); 856 857 // Otherwise, fake up a POD copy into the block field. 858 } else { 859 // Fake up a new variable so that EmitScalarInit doesn't think 860 // we're referring to the variable in its own initializer. 861 ImplicitParamDecl blockFieldPseudoVar(getContext(), /*DC*/ nullptr, 862 SourceLocation(), /*name*/ nullptr, 863 type); 864 865 // We use one of these or the other depending on whether the 866 // reference is nested. 867 DeclRefExpr declRef(const_cast<VarDecl *>(variable), 868 /*RefersToEnclosingVariableOrCapture*/ CI.isNested(), 869 type, VK_LValue, SourceLocation()); 870 871 ImplicitCastExpr l2r(ImplicitCastExpr::OnStack, type, CK_LValueToRValue, 872 &declRef, VK_RValue); 873 // FIXME: Pass a specific location for the expr init so that the store is 874 // attributed to a reasonable location - otherwise it may be attributed to 875 // locations of subexpressions in the initialization. 876 EmitExprAsInit(&l2r, &blockFieldPseudoVar, 877 MakeAddrLValue(blockField, type, align), 878 /*captured by init*/ false); 879 } 880 881 // Activate the cleanup if layout pushed one. 882 if (!CI.isByRef()) { 883 EHScopeStack::stable_iterator cleanup = capture.getCleanup(); 884 if (cleanup.isValid()) 885 ActivateCleanupBlock(cleanup, blockInfo.DominatingIP); 886 } 887 } 888 889 // Cast to the converted block-pointer type, which happens (somewhat 890 // unfortunately) to be a pointer to function type. 891 llvm::Value *result = 892 Builder.CreateBitCast(blockAddr, 893 ConvertType(blockInfo.getBlockExpr()->getType())); 894 895 return result; 896 } 897 898 899 llvm::Type *CodeGenModule::getBlockDescriptorType() { 900 if (BlockDescriptorType) 901 return BlockDescriptorType; 902 903 llvm::Type *UnsignedLongTy = 904 getTypes().ConvertType(getContext().UnsignedLongTy); 905 906 // struct __block_descriptor { 907 // unsigned long reserved; 908 // unsigned long block_size; 909 // 910 // // later, the following will be added 911 // 912 // struct { 913 // void (*copyHelper)(); 914 // void (*copyHelper)(); 915 // } helpers; // !!! optional 916 // 917 // const char *signature; // the block signature 918 // const char *layout; // reserved 919 // }; 920 BlockDescriptorType = 921 llvm::StructType::create("struct.__block_descriptor", 922 UnsignedLongTy, UnsignedLongTy, nullptr); 923 924 // Now form a pointer to that. 925 BlockDescriptorType = llvm::PointerType::getUnqual(BlockDescriptorType); 926 return BlockDescriptorType; 927 } 928 929 llvm::Type *CodeGenModule::getGenericBlockLiteralType() { 930 if (GenericBlockLiteralType) 931 return GenericBlockLiteralType; 932 933 llvm::Type *BlockDescPtrTy = getBlockDescriptorType(); 934 935 // struct __block_literal_generic { 936 // void *__isa; 937 // int __flags; 938 // int __reserved; 939 // void (*__invoke)(void *); 940 // struct __block_descriptor *__descriptor; 941 // }; 942 GenericBlockLiteralType = 943 llvm::StructType::create("struct.__block_literal_generic", 944 VoidPtrTy, IntTy, IntTy, VoidPtrTy, 945 BlockDescPtrTy, nullptr); 946 947 return GenericBlockLiteralType; 948 } 949 950 951 RValue CodeGenFunction::EmitBlockCallExpr(const CallExpr *E, 952 ReturnValueSlot ReturnValue) { 953 const BlockPointerType *BPT = 954 E->getCallee()->getType()->getAs<BlockPointerType>(); 955 956 llvm::Value *Callee = EmitScalarExpr(E->getCallee()); 957 958 // Get a pointer to the generic block literal. 959 llvm::Type *BlockLiteralTy = 960 llvm::PointerType::getUnqual(CGM.getGenericBlockLiteralType()); 961 962 // Bitcast the callee to a block literal. 963 llvm::Value *BlockLiteral = 964 Builder.CreateBitCast(Callee, BlockLiteralTy, "block.literal"); 965 966 // Get the function pointer from the literal. 967 llvm::Value *FuncPtr = Builder.CreateStructGEP(BlockLiteral, 3); 968 969 BlockLiteral = Builder.CreateBitCast(BlockLiteral, VoidPtrTy); 970 971 // Add the block literal. 972 CallArgList Args; 973 Args.add(RValue::get(BlockLiteral), getContext().VoidPtrTy); 974 975 QualType FnType = BPT->getPointeeType(); 976 977 // And the rest of the arguments. 978 EmitCallArgs(Args, FnType->getAs<FunctionProtoType>(), 979 E->arg_begin(), E->arg_end()); 980 981 // Load the function. 982 llvm::Value *Func = Builder.CreateLoad(FuncPtr); 983 984 const FunctionType *FuncTy = FnType->castAs<FunctionType>(); 985 const CGFunctionInfo &FnInfo = 986 CGM.getTypes().arrangeBlockFunctionCall(Args, FuncTy); 987 988 // Cast the function pointer to the right type. 989 llvm::Type *BlockFTy = CGM.getTypes().GetFunctionType(FnInfo); 990 991 llvm::Type *BlockFTyPtr = llvm::PointerType::getUnqual(BlockFTy); 992 Func = Builder.CreateBitCast(Func, BlockFTyPtr); 993 994 // And call the block. 995 return EmitCall(FnInfo, Func, ReturnValue, Args); 996 } 997 998 llvm::Value *CodeGenFunction::GetAddrOfBlockDecl(const VarDecl *variable, 999 bool isByRef) { 1000 assert(BlockInfo && "evaluating block ref without block information?"); 1001 const CGBlockInfo::Capture &capture = BlockInfo->getCapture(variable); 1002 1003 // Handle constant captures. 1004 if (capture.isConstant()) return LocalDeclMap[variable]; 1005 1006 llvm::Value *addr = 1007 Builder.CreateStructGEP(LoadBlockStruct(), capture.getIndex(), 1008 "block.capture.addr"); 1009 1010 if (isByRef) { 1011 // addr should be a void** right now. Load, then cast the result 1012 // to byref*. 1013 1014 addr = Builder.CreateLoad(addr); 1015 llvm::PointerType *byrefPointerType 1016 = llvm::PointerType::get(BuildByRefType(variable), 0); 1017 addr = Builder.CreateBitCast(addr, byrefPointerType, 1018 "byref.addr"); 1019 1020 // Follow the forwarding pointer. 1021 addr = Builder.CreateStructGEP(addr, 1, "byref.forwarding"); 1022 addr = Builder.CreateLoad(addr, "byref.addr.forwarded"); 1023 1024 // Cast back to byref* and GEP over to the actual object. 1025 addr = Builder.CreateBitCast(addr, byrefPointerType); 1026 addr = Builder.CreateStructGEP(addr, getByRefValueLLVMField(variable), 1027 variable->getNameAsString()); 1028 } 1029 1030 if (variable->getType()->isReferenceType()) 1031 addr = Builder.CreateLoad(addr, "ref.tmp"); 1032 1033 return addr; 1034 } 1035 1036 llvm::Constant * 1037 CodeGenModule::GetAddrOfGlobalBlock(const BlockExpr *blockExpr, 1038 const char *name) { 1039 CGBlockInfo blockInfo(blockExpr->getBlockDecl(), name); 1040 blockInfo.BlockExpression = blockExpr; 1041 1042 // Compute information about the layout, etc., of this block. 1043 computeBlockInfo(*this, nullptr, blockInfo); 1044 1045 // Using that metadata, generate the actual block function. 1046 llvm::Constant *blockFn; 1047 { 1048 llvm::DenseMap<const Decl*, llvm::Value*> LocalDeclMap; 1049 blockFn = CodeGenFunction(*this).GenerateBlockFunction(GlobalDecl(), 1050 blockInfo, 1051 LocalDeclMap, 1052 false); 1053 } 1054 blockFn = llvm::ConstantExpr::getBitCast(blockFn, VoidPtrTy); 1055 1056 return buildGlobalBlock(*this, blockInfo, blockFn); 1057 } 1058 1059 static llvm::Constant *buildGlobalBlock(CodeGenModule &CGM, 1060 const CGBlockInfo &blockInfo, 1061 llvm::Constant *blockFn) { 1062 assert(blockInfo.CanBeGlobal); 1063 1064 // Generate the constants for the block literal initializer. 1065 llvm::Constant *fields[BlockHeaderSize]; 1066 1067 // isa 1068 fields[0] = CGM.getNSConcreteGlobalBlock(); 1069 1070 // __flags 1071 BlockFlags flags = BLOCK_IS_GLOBAL | BLOCK_HAS_SIGNATURE; 1072 if (blockInfo.UsesStret) flags |= BLOCK_USE_STRET; 1073 1074 fields[1] = llvm::ConstantInt::get(CGM.IntTy, flags.getBitMask()); 1075 1076 // Reserved 1077 fields[2] = llvm::Constant::getNullValue(CGM.IntTy); 1078 1079 // Function 1080 fields[3] = blockFn; 1081 1082 // Descriptor 1083 fields[4] = buildBlockDescriptor(CGM, blockInfo); 1084 1085 llvm::Constant *init = llvm::ConstantStruct::getAnon(fields); 1086 1087 llvm::GlobalVariable *literal = 1088 new llvm::GlobalVariable(CGM.getModule(), 1089 init->getType(), 1090 /*constant*/ true, 1091 llvm::GlobalVariable::InternalLinkage, 1092 init, 1093 "__block_literal_global"); 1094 literal->setAlignment(blockInfo.BlockAlign.getQuantity()); 1095 1096 // Return a constant of the appropriately-casted type. 1097 llvm::Type *requiredType = 1098 CGM.getTypes().ConvertType(blockInfo.getBlockExpr()->getType()); 1099 return llvm::ConstantExpr::getBitCast(literal, requiredType); 1100 } 1101 1102 llvm::Function * 1103 CodeGenFunction::GenerateBlockFunction(GlobalDecl GD, 1104 const CGBlockInfo &blockInfo, 1105 const DeclMapTy &ldm, 1106 bool IsLambdaConversionToBlock) { 1107 const BlockDecl *blockDecl = blockInfo.getBlockDecl(); 1108 1109 CurGD = GD; 1110 1111 CurEHLocation = blockInfo.getBlockExpr()->getLocEnd(); 1112 1113 BlockInfo = &blockInfo; 1114 1115 // Arrange for local static and local extern declarations to appear 1116 // to be local to this function as well, in case they're directly 1117 // referenced in a block. 1118 for (DeclMapTy::const_iterator i = ldm.begin(), e = ldm.end(); i != e; ++i) { 1119 const auto *var = dyn_cast<VarDecl>(i->first); 1120 if (var && !var->hasLocalStorage()) 1121 LocalDeclMap[var] = i->second; 1122 } 1123 1124 // Begin building the function declaration. 1125 1126 // Build the argument list. 1127 FunctionArgList args; 1128 1129 // The first argument is the block pointer. Just take it as a void* 1130 // and cast it later. 1131 QualType selfTy = getContext().VoidPtrTy; 1132 IdentifierInfo *II = &CGM.getContext().Idents.get(".block_descriptor"); 1133 1134 ImplicitParamDecl selfDecl(getContext(), const_cast<BlockDecl*>(blockDecl), 1135 SourceLocation(), II, selfTy); 1136 args.push_back(&selfDecl); 1137 1138 // Now add the rest of the parameters. 1139 for (auto i : blockDecl->params()) 1140 args.push_back(i); 1141 1142 // Create the function declaration. 1143 const FunctionProtoType *fnType = blockInfo.getBlockExpr()->getFunctionType(); 1144 const CGFunctionInfo &fnInfo = CGM.getTypes().arrangeFreeFunctionDeclaration( 1145 fnType->getReturnType(), args, fnType->getExtInfo(), 1146 fnType->isVariadic()); 1147 if (CGM.ReturnSlotInterferesWithArgs(fnInfo)) 1148 blockInfo.UsesStret = true; 1149 1150 llvm::FunctionType *fnLLVMType = CGM.getTypes().GetFunctionType(fnInfo); 1151 1152 StringRef name = CGM.getBlockMangledName(GD, blockDecl); 1153 llvm::Function *fn = llvm::Function::Create( 1154 fnLLVMType, llvm::GlobalValue::InternalLinkage, name, &CGM.getModule()); 1155 CGM.SetInternalFunctionAttributes(blockDecl, fn, fnInfo); 1156 1157 // Begin generating the function. 1158 StartFunction(blockDecl, fnType->getReturnType(), fn, fnInfo, args, 1159 blockDecl->getLocation(), 1160 blockInfo.getBlockExpr()->getBody()->getLocStart()); 1161 1162 // Okay. Undo some of what StartFunction did. 1163 1164 // Pull the 'self' reference out of the local decl map. 1165 llvm::Value *blockAddr = LocalDeclMap[&selfDecl]; 1166 LocalDeclMap.erase(&selfDecl); 1167 BlockPointer = Builder.CreateBitCast(blockAddr, 1168 blockInfo.StructureType->getPointerTo(), 1169 "block"); 1170 // At -O0 we generate an explicit alloca for the BlockPointer, so the RA 1171 // won't delete the dbg.declare intrinsics for captured variables. 1172 llvm::Value *BlockPointerDbgLoc = BlockPointer; 1173 if (CGM.getCodeGenOpts().OptimizationLevel == 0) { 1174 // Allocate a stack slot for it, so we can point the debugger to it 1175 llvm::AllocaInst *Alloca = CreateTempAlloca(BlockPointer->getType(), 1176 "block.addr"); 1177 unsigned Align = getContext().getDeclAlign(&selfDecl).getQuantity(); 1178 Alloca->setAlignment(Align); 1179 // Set the DebugLocation to empty, so the store is recognized as a 1180 // frame setup instruction by llvm::DwarfDebug::beginFunction(). 1181 ApplyDebugLocation NL(*this); 1182 Builder.CreateAlignedStore(BlockPointer, Alloca, Align); 1183 BlockPointerDbgLoc = Alloca; 1184 } 1185 1186 // If we have a C++ 'this' reference, go ahead and force it into 1187 // existence now. 1188 if (blockDecl->capturesCXXThis()) { 1189 llvm::Value *addr = Builder.CreateStructGEP(BlockPointer, 1190 blockInfo.CXXThisIndex, 1191 "block.captured-this"); 1192 CXXThisValue = Builder.CreateLoad(addr, "this"); 1193 } 1194 1195 // Also force all the constant captures. 1196 for (const auto &CI : blockDecl->captures()) { 1197 const VarDecl *variable = CI.getVariable(); 1198 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable); 1199 if (!capture.isConstant()) continue; 1200 1201 unsigned align = getContext().getDeclAlign(variable).getQuantity(); 1202 1203 llvm::AllocaInst *alloca = 1204 CreateMemTemp(variable->getType(), "block.captured-const"); 1205 alloca->setAlignment(align); 1206 1207 Builder.CreateAlignedStore(capture.getConstant(), alloca, align); 1208 1209 LocalDeclMap[variable] = alloca; 1210 } 1211 1212 // Save a spot to insert the debug information for all the DeclRefExprs. 1213 llvm::BasicBlock *entry = Builder.GetInsertBlock(); 1214 llvm::BasicBlock::iterator entry_ptr = Builder.GetInsertPoint(); 1215 --entry_ptr; 1216 1217 if (IsLambdaConversionToBlock) 1218 EmitLambdaBlockInvokeBody(); 1219 else { 1220 PGO.assignRegionCounters(blockDecl, fn); 1221 RegionCounter Cnt = getPGORegionCounter(blockDecl->getBody()); 1222 Cnt.beginRegion(Builder); 1223 EmitStmt(blockDecl->getBody()); 1224 } 1225 1226 // Remember where we were... 1227 llvm::BasicBlock *resume = Builder.GetInsertBlock(); 1228 1229 // Go back to the entry. 1230 ++entry_ptr; 1231 Builder.SetInsertPoint(entry, entry_ptr); 1232 1233 // Emit debug information for all the DeclRefExprs. 1234 // FIXME: also for 'this' 1235 if (CGDebugInfo *DI = getDebugInfo()) { 1236 for (const auto &CI : blockDecl->captures()) { 1237 const VarDecl *variable = CI.getVariable(); 1238 DI->EmitLocation(Builder, variable->getLocation()); 1239 1240 if (CGM.getCodeGenOpts().getDebugInfo() 1241 >= CodeGenOptions::LimitedDebugInfo) { 1242 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable); 1243 if (capture.isConstant()) { 1244 DI->EmitDeclareOfAutoVariable(variable, LocalDeclMap[variable], 1245 Builder); 1246 continue; 1247 } 1248 1249 DI->EmitDeclareOfBlockDeclRefVariable(variable, BlockPointerDbgLoc, 1250 Builder, blockInfo, 1251 entry_ptr == entry->end() 1252 ? nullptr : entry_ptr); 1253 } 1254 } 1255 // Recover location if it was changed in the above loop. 1256 DI->EmitLocation(Builder, 1257 cast<CompoundStmt>(blockDecl->getBody())->getRBracLoc()); 1258 } 1259 1260 // And resume where we left off. 1261 if (resume == nullptr) 1262 Builder.ClearInsertionPoint(); 1263 else 1264 Builder.SetInsertPoint(resume); 1265 1266 FinishFunction(cast<CompoundStmt>(blockDecl->getBody())->getRBracLoc()); 1267 1268 return fn; 1269 } 1270 1271 /* 1272 notes.push_back(HelperInfo()); 1273 HelperInfo ¬e = notes.back(); 1274 note.index = capture.getIndex(); 1275 note.RequiresCopying = (ci->hasCopyExpr() || BlockRequiresCopying(type)); 1276 note.cxxbar_import = ci->getCopyExpr(); 1277 1278 if (ci->isByRef()) { 1279 note.flag = BLOCK_FIELD_IS_BYREF; 1280 if (type.isObjCGCWeak()) 1281 note.flag |= BLOCK_FIELD_IS_WEAK; 1282 } else if (type->isBlockPointerType()) { 1283 note.flag = BLOCK_FIELD_IS_BLOCK; 1284 } else { 1285 note.flag = BLOCK_FIELD_IS_OBJECT; 1286 } 1287 */ 1288 1289 1290 /// Generate the copy-helper function for a block closure object: 1291 /// static void block_copy_helper(block_t *dst, block_t *src); 1292 /// The runtime will have previously initialized 'dst' by doing a 1293 /// bit-copy of 'src'. 1294 /// 1295 /// Note that this copies an entire block closure object to the heap; 1296 /// it should not be confused with a 'byref copy helper', which moves 1297 /// the contents of an individual __block variable to the heap. 1298 llvm::Constant * 1299 CodeGenFunction::GenerateCopyHelperFunction(const CGBlockInfo &blockInfo) { 1300 ASTContext &C = getContext(); 1301 1302 FunctionArgList args; 1303 ImplicitParamDecl dstDecl(getContext(), nullptr, SourceLocation(), nullptr, 1304 C.VoidPtrTy); 1305 args.push_back(&dstDecl); 1306 ImplicitParamDecl srcDecl(getContext(), nullptr, SourceLocation(), nullptr, 1307 C.VoidPtrTy); 1308 args.push_back(&srcDecl); 1309 1310 const CGFunctionInfo &FI = CGM.getTypes().arrangeFreeFunctionDeclaration( 1311 C.VoidTy, args, FunctionType::ExtInfo(), /*variadic=*/false); 1312 1313 // FIXME: it would be nice if these were mergeable with things with 1314 // identical semantics. 1315 llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI); 1316 1317 llvm::Function *Fn = 1318 llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage, 1319 "__copy_helper_block_", &CGM.getModule()); 1320 1321 IdentifierInfo *II 1322 = &CGM.getContext().Idents.get("__copy_helper_block_"); 1323 1324 FunctionDecl *FD = FunctionDecl::Create(C, 1325 C.getTranslationUnitDecl(), 1326 SourceLocation(), 1327 SourceLocation(), II, C.VoidTy, 1328 nullptr, SC_Static, 1329 false, 1330 false); 1331 // Create a scope with an artificial location for the body of this function. 1332 ApplyDebugLocation NL(*this); 1333 StartFunction(FD, C.VoidTy, Fn, FI, args); 1334 ArtificialLocation AL(*this); 1335 1336 llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo(); 1337 1338 llvm::Value *src = GetAddrOfLocalVar(&srcDecl); 1339 src = Builder.CreateLoad(src); 1340 src = Builder.CreateBitCast(src, structPtrTy, "block.source"); 1341 1342 llvm::Value *dst = GetAddrOfLocalVar(&dstDecl); 1343 dst = Builder.CreateLoad(dst); 1344 dst = Builder.CreateBitCast(dst, structPtrTy, "block.dest"); 1345 1346 const BlockDecl *blockDecl = blockInfo.getBlockDecl(); 1347 1348 for (const auto &CI : blockDecl->captures()) { 1349 const VarDecl *variable = CI.getVariable(); 1350 QualType type = variable->getType(); 1351 1352 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable); 1353 if (capture.isConstant()) continue; 1354 1355 const Expr *copyExpr = CI.getCopyExpr(); 1356 BlockFieldFlags flags; 1357 1358 bool useARCWeakCopy = false; 1359 bool useARCStrongCopy = false; 1360 1361 if (copyExpr) { 1362 assert(!CI.isByRef()); 1363 // don't bother computing flags 1364 1365 } else if (CI.isByRef()) { 1366 flags = BLOCK_FIELD_IS_BYREF; 1367 if (type.isObjCGCWeak()) 1368 flags |= BLOCK_FIELD_IS_WEAK; 1369 1370 } else if (type->isObjCRetainableType()) { 1371 flags = BLOCK_FIELD_IS_OBJECT; 1372 bool isBlockPointer = type->isBlockPointerType(); 1373 if (isBlockPointer) 1374 flags = BLOCK_FIELD_IS_BLOCK; 1375 1376 // Special rules for ARC captures: 1377 if (getLangOpts().ObjCAutoRefCount) { 1378 Qualifiers qs = type.getQualifiers(); 1379 1380 // We need to register __weak direct captures with the runtime. 1381 if (qs.getObjCLifetime() == Qualifiers::OCL_Weak) { 1382 useARCWeakCopy = true; 1383 1384 // We need to retain the copied value for __strong direct captures. 1385 } else if (qs.getObjCLifetime() == Qualifiers::OCL_Strong) { 1386 // If it's a block pointer, we have to copy the block and 1387 // assign that to the destination pointer, so we might as 1388 // well use _Block_object_assign. Otherwise we can avoid that. 1389 if (!isBlockPointer) 1390 useARCStrongCopy = true; 1391 1392 // Otherwise the memcpy is fine. 1393 } else { 1394 continue; 1395 } 1396 1397 // Non-ARC captures of retainable pointers are strong and 1398 // therefore require a call to _Block_object_assign. 1399 } else { 1400 // fall through 1401 } 1402 } else { 1403 continue; 1404 } 1405 1406 unsigned index = capture.getIndex(); 1407 llvm::Value *srcField = Builder.CreateStructGEP(src, index); 1408 llvm::Value *dstField = Builder.CreateStructGEP(dst, index); 1409 1410 // If there's an explicit copy expression, we do that. 1411 if (copyExpr) { 1412 EmitSynthesizedCXXCopyCtor(dstField, srcField, copyExpr); 1413 } else if (useARCWeakCopy) { 1414 EmitARCCopyWeak(dstField, srcField); 1415 } else { 1416 llvm::Value *srcValue = Builder.CreateLoad(srcField, "blockcopy.src"); 1417 if (useARCStrongCopy) { 1418 // At -O0, store null into the destination field (so that the 1419 // storeStrong doesn't over-release) and then call storeStrong. 1420 // This is a workaround to not having an initStrong call. 1421 if (CGM.getCodeGenOpts().OptimizationLevel == 0) { 1422 auto *ty = cast<llvm::PointerType>(srcValue->getType()); 1423 llvm::Value *null = llvm::ConstantPointerNull::get(ty); 1424 Builder.CreateStore(null, dstField); 1425 EmitARCStoreStrongCall(dstField, srcValue, true); 1426 1427 // With optimization enabled, take advantage of the fact that 1428 // the blocks runtime guarantees a memcpy of the block data, and 1429 // just emit a retain of the src field. 1430 } else { 1431 EmitARCRetainNonBlock(srcValue); 1432 1433 // We don't need this anymore, so kill it. It's not quite 1434 // worth the annoyance to avoid creating it in the first place. 1435 cast<llvm::Instruction>(dstField)->eraseFromParent(); 1436 } 1437 } else { 1438 srcValue = Builder.CreateBitCast(srcValue, VoidPtrTy); 1439 llvm::Value *dstAddr = Builder.CreateBitCast(dstField, VoidPtrTy); 1440 llvm::Value *args[] = { 1441 dstAddr, srcValue, llvm::ConstantInt::get(Int32Ty, flags.getBitMask()) 1442 }; 1443 1444 bool copyCanThrow = false; 1445 if (CI.isByRef() && variable->getType()->getAsCXXRecordDecl()) { 1446 const Expr *copyExpr = 1447 CGM.getContext().getBlockVarCopyInits(variable); 1448 if (copyExpr) { 1449 copyCanThrow = true; // FIXME: reuse the noexcept logic 1450 } 1451 } 1452 1453 if (copyCanThrow) { 1454 EmitRuntimeCallOrInvoke(CGM.getBlockObjectAssign(), args); 1455 } else { 1456 EmitNounwindRuntimeCall(CGM.getBlockObjectAssign(), args); 1457 } 1458 } 1459 } 1460 } 1461 1462 FinishFunction(); 1463 1464 return llvm::ConstantExpr::getBitCast(Fn, VoidPtrTy); 1465 } 1466 1467 /// Generate the destroy-helper function for a block closure object: 1468 /// static void block_destroy_helper(block_t *theBlock); 1469 /// 1470 /// Note that this destroys a heap-allocated block closure object; 1471 /// it should not be confused with a 'byref destroy helper', which 1472 /// destroys the heap-allocated contents of an individual __block 1473 /// variable. 1474 llvm::Constant * 1475 CodeGenFunction::GenerateDestroyHelperFunction(const CGBlockInfo &blockInfo) { 1476 ASTContext &C = getContext(); 1477 1478 FunctionArgList args; 1479 ImplicitParamDecl srcDecl(getContext(), nullptr, SourceLocation(), nullptr, 1480 C.VoidPtrTy); 1481 args.push_back(&srcDecl); 1482 1483 const CGFunctionInfo &FI = CGM.getTypes().arrangeFreeFunctionDeclaration( 1484 C.VoidTy, args, FunctionType::ExtInfo(), /*variadic=*/false); 1485 1486 // FIXME: We'd like to put these into a mergable by content, with 1487 // internal linkage. 1488 llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI); 1489 1490 llvm::Function *Fn = 1491 llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage, 1492 "__destroy_helper_block_", &CGM.getModule()); 1493 1494 IdentifierInfo *II 1495 = &CGM.getContext().Idents.get("__destroy_helper_block_"); 1496 1497 FunctionDecl *FD = FunctionDecl::Create(C, C.getTranslationUnitDecl(), 1498 SourceLocation(), 1499 SourceLocation(), II, C.VoidTy, 1500 nullptr, SC_Static, 1501 false, false); 1502 // Create a scope with an artificial location for the body of this function. 1503 ApplyDebugLocation NL(*this); 1504 StartFunction(FD, C.VoidTy, Fn, FI, args); 1505 ArtificialLocation AL(*this); 1506 1507 llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo(); 1508 1509 llvm::Value *src = GetAddrOfLocalVar(&srcDecl); 1510 src = Builder.CreateLoad(src); 1511 src = Builder.CreateBitCast(src, structPtrTy, "block"); 1512 1513 const BlockDecl *blockDecl = blockInfo.getBlockDecl(); 1514 1515 CodeGenFunction::RunCleanupsScope cleanups(*this); 1516 1517 for (const auto &CI : blockDecl->captures()) { 1518 const VarDecl *variable = CI.getVariable(); 1519 QualType type = variable->getType(); 1520 1521 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable); 1522 if (capture.isConstant()) continue; 1523 1524 BlockFieldFlags flags; 1525 const CXXDestructorDecl *dtor = nullptr; 1526 1527 bool useARCWeakDestroy = false; 1528 bool useARCStrongDestroy = false; 1529 1530 if (CI.isByRef()) { 1531 flags = BLOCK_FIELD_IS_BYREF; 1532 if (type.isObjCGCWeak()) 1533 flags |= BLOCK_FIELD_IS_WEAK; 1534 } else if (const CXXRecordDecl *record = type->getAsCXXRecordDecl()) { 1535 if (record->hasTrivialDestructor()) 1536 continue; 1537 dtor = record->getDestructor(); 1538 } else if (type->isObjCRetainableType()) { 1539 flags = BLOCK_FIELD_IS_OBJECT; 1540 if (type->isBlockPointerType()) 1541 flags = BLOCK_FIELD_IS_BLOCK; 1542 1543 // Special rules for ARC captures. 1544 if (getLangOpts().ObjCAutoRefCount) { 1545 Qualifiers qs = type.getQualifiers(); 1546 1547 // Don't generate special dispose logic for a captured object 1548 // unless it's __strong or __weak. 1549 if (!qs.hasStrongOrWeakObjCLifetime()) 1550 continue; 1551 1552 // Support __weak direct captures. 1553 if (qs.getObjCLifetime() == Qualifiers::OCL_Weak) 1554 useARCWeakDestroy = true; 1555 1556 // Tools really want us to use objc_storeStrong here. 1557 else 1558 useARCStrongDestroy = true; 1559 } 1560 } else { 1561 continue; 1562 } 1563 1564 unsigned index = capture.getIndex(); 1565 llvm::Value *srcField = Builder.CreateStructGEP(src, index); 1566 1567 // If there's an explicit copy expression, we do that. 1568 if (dtor) { 1569 PushDestructorCleanup(dtor, srcField); 1570 1571 // If this is a __weak capture, emit the release directly. 1572 } else if (useARCWeakDestroy) { 1573 EmitARCDestroyWeak(srcField); 1574 1575 // Destroy strong objects with a call if requested. 1576 } else if (useARCStrongDestroy) { 1577 EmitARCDestroyStrong(srcField, ARCImpreciseLifetime); 1578 1579 // Otherwise we call _Block_object_dispose. It wouldn't be too 1580 // hard to just emit this as a cleanup if we wanted to make sure 1581 // that things were done in reverse. 1582 } else { 1583 llvm::Value *value = Builder.CreateLoad(srcField); 1584 value = Builder.CreateBitCast(value, VoidPtrTy); 1585 BuildBlockRelease(value, flags); 1586 } 1587 } 1588 1589 cleanups.ForceCleanup(); 1590 1591 FinishFunction(); 1592 1593 return llvm::ConstantExpr::getBitCast(Fn, VoidPtrTy); 1594 } 1595 1596 namespace { 1597 1598 /// Emits the copy/dispose helper functions for a __block object of id type. 1599 class ObjectByrefHelpers : public CodeGenModule::ByrefHelpers { 1600 BlockFieldFlags Flags; 1601 1602 public: 1603 ObjectByrefHelpers(CharUnits alignment, BlockFieldFlags flags) 1604 : ByrefHelpers(alignment), Flags(flags) {} 1605 1606 void emitCopy(CodeGenFunction &CGF, llvm::Value *destField, 1607 llvm::Value *srcField) override { 1608 destField = CGF.Builder.CreateBitCast(destField, CGF.VoidPtrTy); 1609 1610 srcField = CGF.Builder.CreateBitCast(srcField, CGF.VoidPtrPtrTy); 1611 llvm::Value *srcValue = CGF.Builder.CreateLoad(srcField); 1612 1613 unsigned flags = (Flags | BLOCK_BYREF_CALLER).getBitMask(); 1614 1615 llvm::Value *flagsVal = llvm::ConstantInt::get(CGF.Int32Ty, flags); 1616 llvm::Value *fn = CGF.CGM.getBlockObjectAssign(); 1617 1618 llvm::Value *args[] = { destField, srcValue, flagsVal }; 1619 CGF.EmitNounwindRuntimeCall(fn, args); 1620 } 1621 1622 void emitDispose(CodeGenFunction &CGF, llvm::Value *field) override { 1623 field = CGF.Builder.CreateBitCast(field, CGF.Int8PtrTy->getPointerTo(0)); 1624 llvm::Value *value = CGF.Builder.CreateLoad(field); 1625 1626 CGF.BuildBlockRelease(value, Flags | BLOCK_BYREF_CALLER); 1627 } 1628 1629 void profileImpl(llvm::FoldingSetNodeID &id) const override { 1630 id.AddInteger(Flags.getBitMask()); 1631 } 1632 }; 1633 1634 /// Emits the copy/dispose helpers for an ARC __block __weak variable. 1635 class ARCWeakByrefHelpers : public CodeGenModule::ByrefHelpers { 1636 public: 1637 ARCWeakByrefHelpers(CharUnits alignment) : ByrefHelpers(alignment) {} 1638 1639 void emitCopy(CodeGenFunction &CGF, llvm::Value *destField, 1640 llvm::Value *srcField) override { 1641 CGF.EmitARCMoveWeak(destField, srcField); 1642 } 1643 1644 void emitDispose(CodeGenFunction &CGF, llvm::Value *field) override { 1645 CGF.EmitARCDestroyWeak(field); 1646 } 1647 1648 void profileImpl(llvm::FoldingSetNodeID &id) const override { 1649 // 0 is distinguishable from all pointers and byref flags 1650 id.AddInteger(0); 1651 } 1652 }; 1653 1654 /// Emits the copy/dispose helpers for an ARC __block __strong variable 1655 /// that's not of block-pointer type. 1656 class ARCStrongByrefHelpers : public CodeGenModule::ByrefHelpers { 1657 public: 1658 ARCStrongByrefHelpers(CharUnits alignment) : ByrefHelpers(alignment) {} 1659 1660 void emitCopy(CodeGenFunction &CGF, llvm::Value *destField, 1661 llvm::Value *srcField) override { 1662 // Do a "move" by copying the value and then zeroing out the old 1663 // variable. 1664 1665 llvm::LoadInst *value = CGF.Builder.CreateLoad(srcField); 1666 value->setAlignment(Alignment.getQuantity()); 1667 1668 llvm::Value *null = 1669 llvm::ConstantPointerNull::get(cast<llvm::PointerType>(value->getType())); 1670 1671 if (CGF.CGM.getCodeGenOpts().OptimizationLevel == 0) { 1672 llvm::StoreInst *store = CGF.Builder.CreateStore(null, destField); 1673 store->setAlignment(Alignment.getQuantity()); 1674 CGF.EmitARCStoreStrongCall(destField, value, /*ignored*/ true); 1675 CGF.EmitARCStoreStrongCall(srcField, null, /*ignored*/ true); 1676 return; 1677 } 1678 llvm::StoreInst *store = CGF.Builder.CreateStore(value, destField); 1679 store->setAlignment(Alignment.getQuantity()); 1680 1681 store = CGF.Builder.CreateStore(null, srcField); 1682 store->setAlignment(Alignment.getQuantity()); 1683 } 1684 1685 void emitDispose(CodeGenFunction &CGF, llvm::Value *field) override { 1686 CGF.EmitARCDestroyStrong(field, ARCImpreciseLifetime); 1687 } 1688 1689 void profileImpl(llvm::FoldingSetNodeID &id) const override { 1690 // 1 is distinguishable from all pointers and byref flags 1691 id.AddInteger(1); 1692 } 1693 }; 1694 1695 /// Emits the copy/dispose helpers for an ARC __block __strong 1696 /// variable that's of block-pointer type. 1697 class ARCStrongBlockByrefHelpers : public CodeGenModule::ByrefHelpers { 1698 public: 1699 ARCStrongBlockByrefHelpers(CharUnits alignment) : ByrefHelpers(alignment) {} 1700 1701 void emitCopy(CodeGenFunction &CGF, llvm::Value *destField, 1702 llvm::Value *srcField) override { 1703 // Do the copy with objc_retainBlock; that's all that 1704 // _Block_object_assign would do anyway, and we'd have to pass the 1705 // right arguments to make sure it doesn't get no-op'ed. 1706 llvm::LoadInst *oldValue = CGF.Builder.CreateLoad(srcField); 1707 oldValue->setAlignment(Alignment.getQuantity()); 1708 1709 llvm::Value *copy = CGF.EmitARCRetainBlock(oldValue, /*mandatory*/ true); 1710 1711 llvm::StoreInst *store = CGF.Builder.CreateStore(copy, destField); 1712 store->setAlignment(Alignment.getQuantity()); 1713 } 1714 1715 void emitDispose(CodeGenFunction &CGF, llvm::Value *field) override { 1716 CGF.EmitARCDestroyStrong(field, ARCImpreciseLifetime); 1717 } 1718 1719 void profileImpl(llvm::FoldingSetNodeID &id) const override { 1720 // 2 is distinguishable from all pointers and byref flags 1721 id.AddInteger(2); 1722 } 1723 }; 1724 1725 /// Emits the copy/dispose helpers for a __block variable with a 1726 /// nontrivial copy constructor or destructor. 1727 class CXXByrefHelpers : public CodeGenModule::ByrefHelpers { 1728 QualType VarType; 1729 const Expr *CopyExpr; 1730 1731 public: 1732 CXXByrefHelpers(CharUnits alignment, QualType type, 1733 const Expr *copyExpr) 1734 : ByrefHelpers(alignment), VarType(type), CopyExpr(copyExpr) {} 1735 1736 bool needsCopy() const override { return CopyExpr != nullptr; } 1737 void emitCopy(CodeGenFunction &CGF, llvm::Value *destField, 1738 llvm::Value *srcField) override { 1739 if (!CopyExpr) return; 1740 CGF.EmitSynthesizedCXXCopyCtor(destField, srcField, CopyExpr); 1741 } 1742 1743 void emitDispose(CodeGenFunction &CGF, llvm::Value *field) override { 1744 EHScopeStack::stable_iterator cleanupDepth = CGF.EHStack.stable_begin(); 1745 CGF.PushDestructorCleanup(VarType, field); 1746 CGF.PopCleanupBlocks(cleanupDepth); 1747 } 1748 1749 void profileImpl(llvm::FoldingSetNodeID &id) const override { 1750 id.AddPointer(VarType.getCanonicalType().getAsOpaquePtr()); 1751 } 1752 }; 1753 } // end anonymous namespace 1754 1755 static llvm::Constant * 1756 generateByrefCopyHelper(CodeGenFunction &CGF, 1757 llvm::StructType &byrefType, 1758 unsigned valueFieldIndex, 1759 CodeGenModule::ByrefHelpers &byrefInfo) { 1760 ASTContext &Context = CGF.getContext(); 1761 1762 QualType R = Context.VoidTy; 1763 1764 FunctionArgList args; 1765 ImplicitParamDecl dst(CGF.getContext(), nullptr, SourceLocation(), nullptr, 1766 Context.VoidPtrTy); 1767 args.push_back(&dst); 1768 1769 ImplicitParamDecl src(CGF.getContext(), nullptr, SourceLocation(), nullptr, 1770 Context.VoidPtrTy); 1771 args.push_back(&src); 1772 1773 const CGFunctionInfo &FI = CGF.CGM.getTypes().arrangeFreeFunctionDeclaration( 1774 R, args, FunctionType::ExtInfo(), /*variadic=*/false); 1775 1776 CodeGenTypes &Types = CGF.CGM.getTypes(); 1777 llvm::FunctionType *LTy = Types.GetFunctionType(FI); 1778 1779 // FIXME: We'd like to put these into a mergable by content, with 1780 // internal linkage. 1781 llvm::Function *Fn = 1782 llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage, 1783 "__Block_byref_object_copy_", &CGF.CGM.getModule()); 1784 1785 IdentifierInfo *II 1786 = &Context.Idents.get("__Block_byref_object_copy_"); 1787 1788 FunctionDecl *FD = FunctionDecl::Create(Context, 1789 Context.getTranslationUnitDecl(), 1790 SourceLocation(), 1791 SourceLocation(), II, R, nullptr, 1792 SC_Static, 1793 false, false); 1794 1795 CGF.StartFunction(FD, R, Fn, FI, args); 1796 1797 if (byrefInfo.needsCopy()) { 1798 llvm::Type *byrefPtrType = byrefType.getPointerTo(0); 1799 1800 // dst->x 1801 llvm::Value *destField = CGF.GetAddrOfLocalVar(&dst); 1802 destField = CGF.Builder.CreateLoad(destField); 1803 destField = CGF.Builder.CreateBitCast(destField, byrefPtrType); 1804 destField = CGF.Builder.CreateStructGEP(destField, valueFieldIndex, "x"); 1805 1806 // src->x 1807 llvm::Value *srcField = CGF.GetAddrOfLocalVar(&src); 1808 srcField = CGF.Builder.CreateLoad(srcField); 1809 srcField = CGF.Builder.CreateBitCast(srcField, byrefPtrType); 1810 srcField = CGF.Builder.CreateStructGEP(srcField, valueFieldIndex, "x"); 1811 1812 byrefInfo.emitCopy(CGF, destField, srcField); 1813 } 1814 1815 CGF.FinishFunction(); 1816 1817 return llvm::ConstantExpr::getBitCast(Fn, CGF.Int8PtrTy); 1818 } 1819 1820 /// Build the copy helper for a __block variable. 1821 static llvm::Constant *buildByrefCopyHelper(CodeGenModule &CGM, 1822 llvm::StructType &byrefType, 1823 unsigned byrefValueIndex, 1824 CodeGenModule::ByrefHelpers &info) { 1825 CodeGenFunction CGF(CGM); 1826 return generateByrefCopyHelper(CGF, byrefType, byrefValueIndex, info); 1827 } 1828 1829 /// Generate code for a __block variable's dispose helper. 1830 static llvm::Constant * 1831 generateByrefDisposeHelper(CodeGenFunction &CGF, 1832 llvm::StructType &byrefType, 1833 unsigned byrefValueIndex, 1834 CodeGenModule::ByrefHelpers &byrefInfo) { 1835 ASTContext &Context = CGF.getContext(); 1836 QualType R = Context.VoidTy; 1837 1838 FunctionArgList args; 1839 ImplicitParamDecl src(CGF.getContext(), nullptr, SourceLocation(), nullptr, 1840 Context.VoidPtrTy); 1841 args.push_back(&src); 1842 1843 const CGFunctionInfo &FI = CGF.CGM.getTypes().arrangeFreeFunctionDeclaration( 1844 R, args, FunctionType::ExtInfo(), /*variadic=*/false); 1845 1846 CodeGenTypes &Types = CGF.CGM.getTypes(); 1847 llvm::FunctionType *LTy = Types.GetFunctionType(FI); 1848 1849 // FIXME: We'd like to put these into a mergable by content, with 1850 // internal linkage. 1851 llvm::Function *Fn = 1852 llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage, 1853 "__Block_byref_object_dispose_", 1854 &CGF.CGM.getModule()); 1855 1856 IdentifierInfo *II 1857 = &Context.Idents.get("__Block_byref_object_dispose_"); 1858 1859 FunctionDecl *FD = FunctionDecl::Create(Context, 1860 Context.getTranslationUnitDecl(), 1861 SourceLocation(), 1862 SourceLocation(), II, R, nullptr, 1863 SC_Static, 1864 false, false); 1865 CGF.StartFunction(FD, R, Fn, FI, args); 1866 1867 if (byrefInfo.needsDispose()) { 1868 llvm::Value *V = CGF.GetAddrOfLocalVar(&src); 1869 V = CGF.Builder.CreateLoad(V); 1870 V = CGF.Builder.CreateBitCast(V, byrefType.getPointerTo(0)); 1871 V = CGF.Builder.CreateStructGEP(V, byrefValueIndex, "x"); 1872 1873 byrefInfo.emitDispose(CGF, V); 1874 } 1875 1876 CGF.FinishFunction(); 1877 1878 return llvm::ConstantExpr::getBitCast(Fn, CGF.Int8PtrTy); 1879 } 1880 1881 /// Build the dispose helper for a __block variable. 1882 static llvm::Constant *buildByrefDisposeHelper(CodeGenModule &CGM, 1883 llvm::StructType &byrefType, 1884 unsigned byrefValueIndex, 1885 CodeGenModule::ByrefHelpers &info) { 1886 CodeGenFunction CGF(CGM); 1887 return generateByrefDisposeHelper(CGF, byrefType, byrefValueIndex, info); 1888 } 1889 1890 /// Lazily build the copy and dispose helpers for a __block variable 1891 /// with the given information. 1892 template <class T> static T *buildByrefHelpers(CodeGenModule &CGM, 1893 llvm::StructType &byrefTy, 1894 unsigned byrefValueIndex, 1895 T &byrefInfo) { 1896 // Increase the field's alignment to be at least pointer alignment, 1897 // since the layout of the byref struct will guarantee at least that. 1898 byrefInfo.Alignment = std::max(byrefInfo.Alignment, 1899 CharUnits::fromQuantity(CGM.PointerAlignInBytes)); 1900 1901 llvm::FoldingSetNodeID id; 1902 byrefInfo.Profile(id); 1903 1904 void *insertPos; 1905 CodeGenModule::ByrefHelpers *node 1906 = CGM.ByrefHelpersCache.FindNodeOrInsertPos(id, insertPos); 1907 if (node) return static_cast<T*>(node); 1908 1909 byrefInfo.CopyHelper = 1910 buildByrefCopyHelper(CGM, byrefTy, byrefValueIndex, byrefInfo); 1911 byrefInfo.DisposeHelper = 1912 buildByrefDisposeHelper(CGM, byrefTy, byrefValueIndex,byrefInfo); 1913 1914 T *copy = new (CGM.getContext()) T(byrefInfo); 1915 CGM.ByrefHelpersCache.InsertNode(copy, insertPos); 1916 return copy; 1917 } 1918 1919 /// Build the copy and dispose helpers for the given __block variable 1920 /// emission. Places the helpers in the global cache. Returns null 1921 /// if no helpers are required. 1922 CodeGenModule::ByrefHelpers * 1923 CodeGenFunction::buildByrefHelpers(llvm::StructType &byrefType, 1924 const AutoVarEmission &emission) { 1925 const VarDecl &var = *emission.Variable; 1926 QualType type = var.getType(); 1927 1928 unsigned byrefValueIndex = getByRefValueLLVMField(&var); 1929 1930 if (const CXXRecordDecl *record = type->getAsCXXRecordDecl()) { 1931 const Expr *copyExpr = CGM.getContext().getBlockVarCopyInits(&var); 1932 if (!copyExpr && record->hasTrivialDestructor()) return nullptr; 1933 1934 CXXByrefHelpers byrefInfo(emission.Alignment, type, copyExpr); 1935 return ::buildByrefHelpers(CGM, byrefType, byrefValueIndex, byrefInfo); 1936 } 1937 1938 // Otherwise, if we don't have a retainable type, there's nothing to do. 1939 // that the runtime does extra copies. 1940 if (!type->isObjCRetainableType()) return nullptr; 1941 1942 Qualifiers qs = type.getQualifiers(); 1943 1944 // If we have lifetime, that dominates. 1945 if (Qualifiers::ObjCLifetime lifetime = qs.getObjCLifetime()) { 1946 assert(getLangOpts().ObjCAutoRefCount); 1947 1948 switch (lifetime) { 1949 case Qualifiers::OCL_None: llvm_unreachable("impossible"); 1950 1951 // These are just bits as far as the runtime is concerned. 1952 case Qualifiers::OCL_ExplicitNone: 1953 case Qualifiers::OCL_Autoreleasing: 1954 return nullptr; 1955 1956 // Tell the runtime that this is ARC __weak, called by the 1957 // byref routines. 1958 case Qualifiers::OCL_Weak: { 1959 ARCWeakByrefHelpers byrefInfo(emission.Alignment); 1960 return ::buildByrefHelpers(CGM, byrefType, byrefValueIndex, byrefInfo); 1961 } 1962 1963 // ARC __strong __block variables need to be retained. 1964 case Qualifiers::OCL_Strong: 1965 // Block pointers need to be copied, and there's no direct 1966 // transfer possible. 1967 if (type->isBlockPointerType()) { 1968 ARCStrongBlockByrefHelpers byrefInfo(emission.Alignment); 1969 return ::buildByrefHelpers(CGM, byrefType, byrefValueIndex, byrefInfo); 1970 1971 // Otherwise, we transfer ownership of the retain from the stack 1972 // to the heap. 1973 } else { 1974 ARCStrongByrefHelpers byrefInfo(emission.Alignment); 1975 return ::buildByrefHelpers(CGM, byrefType, byrefValueIndex, byrefInfo); 1976 } 1977 } 1978 llvm_unreachable("fell out of lifetime switch!"); 1979 } 1980 1981 BlockFieldFlags flags; 1982 if (type->isBlockPointerType()) { 1983 flags |= BLOCK_FIELD_IS_BLOCK; 1984 } else if (CGM.getContext().isObjCNSObjectType(type) || 1985 type->isObjCObjectPointerType()) { 1986 flags |= BLOCK_FIELD_IS_OBJECT; 1987 } else { 1988 return nullptr; 1989 } 1990 1991 if (type.isObjCGCWeak()) 1992 flags |= BLOCK_FIELD_IS_WEAK; 1993 1994 ObjectByrefHelpers byrefInfo(emission.Alignment, flags); 1995 return ::buildByrefHelpers(CGM, byrefType, byrefValueIndex, byrefInfo); 1996 } 1997 1998 unsigned CodeGenFunction::getByRefValueLLVMField(const ValueDecl *VD) const { 1999 assert(ByRefValueInfo.count(VD) && "Did not find value!"); 2000 2001 return ByRefValueInfo.find(VD)->second.second; 2002 } 2003 2004 llvm::Value *CodeGenFunction::BuildBlockByrefAddress(llvm::Value *BaseAddr, 2005 const VarDecl *V) { 2006 llvm::Value *Loc = Builder.CreateStructGEP(BaseAddr, 1, "forwarding"); 2007 Loc = Builder.CreateLoad(Loc); 2008 Loc = Builder.CreateStructGEP(Loc, getByRefValueLLVMField(V), 2009 V->getNameAsString()); 2010 return Loc; 2011 } 2012 2013 /// BuildByRefType - This routine changes a __block variable declared as T x 2014 /// into: 2015 /// 2016 /// struct { 2017 /// void *__isa; 2018 /// void *__forwarding; 2019 /// int32_t __flags; 2020 /// int32_t __size; 2021 /// void *__copy_helper; // only if needed 2022 /// void *__destroy_helper; // only if needed 2023 /// void *__byref_variable_layout;// only if needed 2024 /// char padding[X]; // only if needed 2025 /// T x; 2026 /// } x 2027 /// 2028 llvm::Type *CodeGenFunction::BuildByRefType(const VarDecl *D) { 2029 std::pair<llvm::Type *, unsigned> &Info = ByRefValueInfo[D]; 2030 if (Info.first) 2031 return Info.first; 2032 2033 QualType Ty = D->getType(); 2034 2035 SmallVector<llvm::Type *, 8> types; 2036 2037 llvm::StructType *ByRefType = 2038 llvm::StructType::create(getLLVMContext(), 2039 "struct.__block_byref_" + D->getNameAsString()); 2040 2041 // void *__isa; 2042 types.push_back(Int8PtrTy); 2043 2044 // void *__forwarding; 2045 types.push_back(llvm::PointerType::getUnqual(ByRefType)); 2046 2047 // int32_t __flags; 2048 types.push_back(Int32Ty); 2049 2050 // int32_t __size; 2051 types.push_back(Int32Ty); 2052 // Note that this must match *exactly* the logic in buildByrefHelpers. 2053 bool HasCopyAndDispose = getContext().BlockRequiresCopying(Ty, D); 2054 if (HasCopyAndDispose) { 2055 /// void *__copy_helper; 2056 types.push_back(Int8PtrTy); 2057 2058 /// void *__destroy_helper; 2059 types.push_back(Int8PtrTy); 2060 } 2061 bool HasByrefExtendedLayout = false; 2062 Qualifiers::ObjCLifetime Lifetime; 2063 if (getContext().getByrefLifetime(Ty, Lifetime, HasByrefExtendedLayout) && 2064 HasByrefExtendedLayout) 2065 /// void *__byref_variable_layout; 2066 types.push_back(Int8PtrTy); 2067 2068 bool Packed = false; 2069 CharUnits Align = getContext().getDeclAlign(D); 2070 if (Align > 2071 getContext().toCharUnitsFromBits(getTarget().getPointerAlign(0))) { 2072 // We have to insert padding. 2073 2074 // The struct above has 2 32-bit integers. 2075 unsigned CurrentOffsetInBytes = 4 * 2; 2076 2077 // And either 2, 3, 4 or 5 pointers. 2078 unsigned noPointers = 2; 2079 if (HasCopyAndDispose) 2080 noPointers += 2; 2081 if (HasByrefExtendedLayout) 2082 noPointers += 1; 2083 2084 CurrentOffsetInBytes += noPointers * CGM.getDataLayout().getTypeAllocSize(Int8PtrTy); 2085 2086 // Align the offset. 2087 unsigned AlignedOffsetInBytes = 2088 llvm::RoundUpToAlignment(CurrentOffsetInBytes, Align.getQuantity()); 2089 2090 unsigned NumPaddingBytes = AlignedOffsetInBytes - CurrentOffsetInBytes; 2091 if (NumPaddingBytes > 0) { 2092 llvm::Type *Ty = Int8Ty; 2093 // FIXME: We need a sema error for alignment larger than the minimum of 2094 // the maximal stack alignment and the alignment of malloc on the system. 2095 if (NumPaddingBytes > 1) 2096 Ty = llvm::ArrayType::get(Ty, NumPaddingBytes); 2097 2098 types.push_back(Ty); 2099 2100 // We want a packed struct. 2101 Packed = true; 2102 } 2103 } 2104 2105 // T x; 2106 types.push_back(ConvertTypeForMem(Ty)); 2107 2108 ByRefType->setBody(types, Packed); 2109 2110 Info.first = ByRefType; 2111 2112 Info.second = types.size() - 1; 2113 2114 return Info.first; 2115 } 2116 2117 /// Initialize the structural components of a __block variable, i.e. 2118 /// everything but the actual object. 2119 void CodeGenFunction::emitByrefStructureInit(const AutoVarEmission &emission) { 2120 // Find the address of the local. 2121 llvm::Value *addr = emission.Address; 2122 2123 // That's an alloca of the byref structure type. 2124 llvm::StructType *byrefType = cast<llvm::StructType>( 2125 cast<llvm::PointerType>(addr->getType())->getElementType()); 2126 2127 // Build the byref helpers if necessary. This is null if we don't need any. 2128 CodeGenModule::ByrefHelpers *helpers = 2129 buildByrefHelpers(*byrefType, emission); 2130 2131 const VarDecl &D = *emission.Variable; 2132 QualType type = D.getType(); 2133 2134 bool HasByrefExtendedLayout; 2135 Qualifiers::ObjCLifetime ByrefLifetime; 2136 bool ByRefHasLifetime = 2137 getContext().getByrefLifetime(type, ByrefLifetime, HasByrefExtendedLayout); 2138 2139 llvm::Value *V; 2140 2141 // Initialize the 'isa', which is just 0 or 1. 2142 int isa = 0; 2143 if (type.isObjCGCWeak()) 2144 isa = 1; 2145 V = Builder.CreateIntToPtr(Builder.getInt32(isa), Int8PtrTy, "isa"); 2146 Builder.CreateStore(V, Builder.CreateStructGEP(addr, 0, "byref.isa")); 2147 2148 // Store the address of the variable into its own forwarding pointer. 2149 Builder.CreateStore(addr, 2150 Builder.CreateStructGEP(addr, 1, "byref.forwarding")); 2151 2152 // Blocks ABI: 2153 // c) the flags field is set to either 0 if no helper functions are 2154 // needed or BLOCK_BYREF_HAS_COPY_DISPOSE if they are, 2155 BlockFlags flags; 2156 if (helpers) flags |= BLOCK_BYREF_HAS_COPY_DISPOSE; 2157 if (ByRefHasLifetime) { 2158 if (HasByrefExtendedLayout) flags |= BLOCK_BYREF_LAYOUT_EXTENDED; 2159 else switch (ByrefLifetime) { 2160 case Qualifiers::OCL_Strong: 2161 flags |= BLOCK_BYREF_LAYOUT_STRONG; 2162 break; 2163 case Qualifiers::OCL_Weak: 2164 flags |= BLOCK_BYREF_LAYOUT_WEAK; 2165 break; 2166 case Qualifiers::OCL_ExplicitNone: 2167 flags |= BLOCK_BYREF_LAYOUT_UNRETAINED; 2168 break; 2169 case Qualifiers::OCL_None: 2170 if (!type->isObjCObjectPointerType() && !type->isBlockPointerType()) 2171 flags |= BLOCK_BYREF_LAYOUT_NON_OBJECT; 2172 break; 2173 default: 2174 break; 2175 } 2176 if (CGM.getLangOpts().ObjCGCBitmapPrint) { 2177 printf("\n Inline flag for BYREF variable layout (%d):", flags.getBitMask()); 2178 if (flags & BLOCK_BYREF_HAS_COPY_DISPOSE) 2179 printf(" BLOCK_BYREF_HAS_COPY_DISPOSE"); 2180 if (flags & BLOCK_BYREF_LAYOUT_MASK) { 2181 BlockFlags ThisFlag(flags.getBitMask() & BLOCK_BYREF_LAYOUT_MASK); 2182 if (ThisFlag == BLOCK_BYREF_LAYOUT_EXTENDED) 2183 printf(" BLOCK_BYREF_LAYOUT_EXTENDED"); 2184 if (ThisFlag == BLOCK_BYREF_LAYOUT_STRONG) 2185 printf(" BLOCK_BYREF_LAYOUT_STRONG"); 2186 if (ThisFlag == BLOCK_BYREF_LAYOUT_WEAK) 2187 printf(" BLOCK_BYREF_LAYOUT_WEAK"); 2188 if (ThisFlag == BLOCK_BYREF_LAYOUT_UNRETAINED) 2189 printf(" BLOCK_BYREF_LAYOUT_UNRETAINED"); 2190 if (ThisFlag == BLOCK_BYREF_LAYOUT_NON_OBJECT) 2191 printf(" BLOCK_BYREF_LAYOUT_NON_OBJECT"); 2192 } 2193 printf("\n"); 2194 } 2195 } 2196 2197 Builder.CreateStore(llvm::ConstantInt::get(IntTy, flags.getBitMask()), 2198 Builder.CreateStructGEP(addr, 2, "byref.flags")); 2199 2200 CharUnits byrefSize = CGM.GetTargetTypeStoreSize(byrefType); 2201 V = llvm::ConstantInt::get(IntTy, byrefSize.getQuantity()); 2202 Builder.CreateStore(V, Builder.CreateStructGEP(addr, 3, "byref.size")); 2203 2204 if (helpers) { 2205 llvm::Value *copy_helper = Builder.CreateStructGEP(addr, 4); 2206 Builder.CreateStore(helpers->CopyHelper, copy_helper); 2207 2208 llvm::Value *destroy_helper = Builder.CreateStructGEP(addr, 5); 2209 Builder.CreateStore(helpers->DisposeHelper, destroy_helper); 2210 } 2211 if (ByRefHasLifetime && HasByrefExtendedLayout) { 2212 llvm::Constant* ByrefLayoutInfo = CGM.getObjCRuntime().BuildByrefLayout(CGM, type); 2213 llvm::Value *ByrefInfoAddr = Builder.CreateStructGEP(addr, helpers ? 6 : 4, 2214 "byref.layout"); 2215 // cast destination to pointer to source type. 2216 llvm::Type *DesTy = ByrefLayoutInfo->getType(); 2217 DesTy = DesTy->getPointerTo(); 2218 llvm::Value *BC = Builder.CreatePointerCast(ByrefInfoAddr, DesTy); 2219 Builder.CreateStore(ByrefLayoutInfo, BC); 2220 } 2221 } 2222 2223 void CodeGenFunction::BuildBlockRelease(llvm::Value *V, BlockFieldFlags flags) { 2224 llvm::Value *F = CGM.getBlockObjectDispose(); 2225 llvm::Value *args[] = { 2226 Builder.CreateBitCast(V, Int8PtrTy), 2227 llvm::ConstantInt::get(Int32Ty, flags.getBitMask()) 2228 }; 2229 EmitNounwindRuntimeCall(F, args); // FIXME: throwing destructors? 2230 } 2231 2232 namespace { 2233 struct CallBlockRelease : EHScopeStack::Cleanup { 2234 llvm::Value *Addr; 2235 CallBlockRelease(llvm::Value *Addr) : Addr(Addr) {} 2236 2237 void Emit(CodeGenFunction &CGF, Flags flags) override { 2238 // Should we be passing FIELD_IS_WEAK here? 2239 CGF.BuildBlockRelease(Addr, BLOCK_FIELD_IS_BYREF); 2240 } 2241 }; 2242 } 2243 2244 /// Enter a cleanup to destroy a __block variable. Note that this 2245 /// cleanup should be a no-op if the variable hasn't left the stack 2246 /// yet; if a cleanup is required for the variable itself, that needs 2247 /// to be done externally. 2248 void CodeGenFunction::enterByrefCleanup(const AutoVarEmission &emission) { 2249 // We don't enter this cleanup if we're in pure-GC mode. 2250 if (CGM.getLangOpts().getGC() == LangOptions::GCOnly) 2251 return; 2252 2253 EHStack.pushCleanup<CallBlockRelease>(NormalAndEHCleanup, emission.Address); 2254 } 2255 2256 /// Adjust the declaration of something from the blocks API. 2257 static void configureBlocksRuntimeObject(CodeGenModule &CGM, 2258 llvm::Constant *C) { 2259 if (!CGM.getLangOpts().BlocksRuntimeOptional) return; 2260 2261 auto *GV = cast<llvm::GlobalValue>(C->stripPointerCasts()); 2262 if (GV->isDeclaration() && GV->hasExternalLinkage()) 2263 GV->setLinkage(llvm::GlobalValue::ExternalWeakLinkage); 2264 } 2265 2266 llvm::Constant *CodeGenModule::getBlockObjectDispose() { 2267 if (BlockObjectDispose) 2268 return BlockObjectDispose; 2269 2270 llvm::Type *args[] = { Int8PtrTy, Int32Ty }; 2271 llvm::FunctionType *fty 2272 = llvm::FunctionType::get(VoidTy, args, false); 2273 BlockObjectDispose = CreateRuntimeFunction(fty, "_Block_object_dispose"); 2274 configureBlocksRuntimeObject(*this, BlockObjectDispose); 2275 return BlockObjectDispose; 2276 } 2277 2278 llvm::Constant *CodeGenModule::getBlockObjectAssign() { 2279 if (BlockObjectAssign) 2280 return BlockObjectAssign; 2281 2282 llvm::Type *args[] = { Int8PtrTy, Int8PtrTy, Int32Ty }; 2283 llvm::FunctionType *fty 2284 = llvm::FunctionType::get(VoidTy, args, false); 2285 BlockObjectAssign = CreateRuntimeFunction(fty, "_Block_object_assign"); 2286 configureBlocksRuntimeObject(*this, BlockObjectAssign); 2287 return BlockObjectAssign; 2288 } 2289 2290 llvm::Constant *CodeGenModule::getNSConcreteGlobalBlock() { 2291 if (NSConcreteGlobalBlock) 2292 return NSConcreteGlobalBlock; 2293 2294 NSConcreteGlobalBlock = GetOrCreateLLVMGlobal("_NSConcreteGlobalBlock", 2295 Int8PtrTy->getPointerTo(), 2296 nullptr); 2297 configureBlocksRuntimeObject(*this, NSConcreteGlobalBlock); 2298 return NSConcreteGlobalBlock; 2299 } 2300 2301 llvm::Constant *CodeGenModule::getNSConcreteStackBlock() { 2302 if (NSConcreteStackBlock) 2303 return NSConcreteStackBlock; 2304 2305 NSConcreteStackBlock = GetOrCreateLLVMGlobal("_NSConcreteStackBlock", 2306 Int8PtrTy->getPointerTo(), 2307 nullptr); 2308 configureBlocksRuntimeObject(*this, NSConcreteStackBlock); 2309 return NSConcreteStackBlock; 2310 } 2311