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 "CGDebugInfo.h" 15 #include "CodeGenFunction.h" 16 #include "CGObjCRuntime.h" 17 #include "CodeGenModule.h" 18 #include "CGBlocks.h" 19 #include "clang/AST/DeclObjC.h" 20 #include "llvm/Module.h" 21 #include "llvm/ADT/SmallSet.h" 22 #include "llvm/Target/TargetData.h" 23 #include <algorithm> 24 25 using namespace clang; 26 using namespace CodeGen; 27 28 CGBlockInfo::CGBlockInfo(const BlockDecl *block, StringRef name) 29 : Name(name), CXXThisIndex(0), CanBeGlobal(false), NeedsCopyDispose(false), 30 HasCXXObject(false), UsesStret(false), StructureType(0), Block(block), 31 DominatingIP(0) { 32 33 // Skip asm prefix, if any. 'name' is usually taken directly from 34 // the mangled name of the enclosing function. 35 if (!name.empty() && name[0] == '\01') 36 name = name.substr(1); 37 } 38 39 // Anchor the vtable to this translation unit. 40 CodeGenModule::ByrefHelpers::~ByrefHelpers() {} 41 42 /// Build the given block as a global block. 43 static llvm::Constant *buildGlobalBlock(CodeGenModule &CGM, 44 const CGBlockInfo &blockInfo, 45 llvm::Constant *blockFn); 46 47 /// Build the helper function to copy a block. 48 static llvm::Constant *buildCopyHelper(CodeGenModule &CGM, 49 const CGBlockInfo &blockInfo) { 50 return CodeGenFunction(CGM).GenerateCopyHelperFunction(blockInfo); 51 } 52 53 /// Build the helper function to dipose of a block. 54 static llvm::Constant *buildDisposeHelper(CodeGenModule &CGM, 55 const CGBlockInfo &blockInfo) { 56 return CodeGenFunction(CGM).GenerateDestroyHelperFunction(blockInfo); 57 } 58 59 /// Build the block descriptor constant for a block. 60 static llvm::Constant *buildBlockDescriptor(CodeGenModule &CGM, 61 const CGBlockInfo &blockInfo) { 62 ASTContext &C = CGM.getContext(); 63 64 llvm::Type *ulong = CGM.getTypes().ConvertType(C.UnsignedLongTy); 65 llvm::Type *i8p = CGM.getTypes().ConvertType(C.VoidPtrTy); 66 67 SmallVector<llvm::Constant*, 6> elements; 68 69 // reserved 70 elements.push_back(llvm::ConstantInt::get(ulong, 0)); 71 72 // Size 73 // FIXME: What is the right way to say this doesn't fit? We should give 74 // a user diagnostic in that case. Better fix would be to change the 75 // API to size_t. 76 elements.push_back(llvm::ConstantInt::get(ulong, 77 blockInfo.BlockSize.getQuantity())); 78 79 // Optional copy/dispose helpers. 80 if (blockInfo.NeedsCopyDispose) { 81 // copy_func_helper_decl 82 elements.push_back(buildCopyHelper(CGM, blockInfo)); 83 84 // destroy_func_decl 85 elements.push_back(buildDisposeHelper(CGM, blockInfo)); 86 } 87 88 // Signature. Mandatory ObjC-style method descriptor @encode sequence. 89 std::string typeAtEncoding = 90 CGM.getContext().getObjCEncodingForBlock(blockInfo.getBlockExpr()); 91 elements.push_back(llvm::ConstantExpr::getBitCast( 92 CGM.GetAddrOfConstantCString(typeAtEncoding), i8p)); 93 94 // GC layout. 95 if (C.getLangOpts().ObjC1) 96 elements.push_back(CGM.getObjCRuntime().BuildGCBlockLayout(CGM, blockInfo)); 97 else 98 elements.push_back(llvm::Constant::getNullValue(i8p)); 99 100 llvm::Constant *init = llvm::ConstantStruct::getAnon(elements); 101 102 llvm::GlobalVariable *global = 103 new llvm::GlobalVariable(CGM.getModule(), init->getType(), true, 104 llvm::GlobalValue::InternalLinkage, 105 init, "__block_descriptor_tmp"); 106 107 return llvm::ConstantExpr::getBitCast(global, CGM.getBlockDescriptorType()); 108 } 109 110 /* 111 Purely notional variadic template describing the layout of a block. 112 113 template <class _ResultType, class... _ParamTypes, class... _CaptureTypes> 114 struct Block_literal { 115 /// Initialized to one of: 116 /// extern void *_NSConcreteStackBlock[]; 117 /// extern void *_NSConcreteGlobalBlock[]; 118 /// 119 /// In theory, we could start one off malloc'ed by setting 120 /// BLOCK_NEEDS_FREE, giving it a refcount of 1, and using 121 /// this isa: 122 /// extern void *_NSConcreteMallocBlock[]; 123 struct objc_class *isa; 124 125 /// These are the flags (with corresponding bit number) that the 126 /// compiler is actually supposed to know about. 127 /// 25. BLOCK_HAS_COPY_DISPOSE - indicates that the block 128 /// descriptor provides copy and dispose helper functions 129 /// 26. BLOCK_HAS_CXX_OBJ - indicates that there's a captured 130 /// object with a nontrivial destructor or copy constructor 131 /// 28. BLOCK_IS_GLOBAL - indicates that the block is allocated 132 /// as global memory 133 /// 29. BLOCK_USE_STRET - indicates that the block function 134 /// uses stret, which objc_msgSend needs to know about 135 /// 30. BLOCK_HAS_SIGNATURE - indicates that the block has an 136 /// @encoded signature string 137 /// And we're not supposed to manipulate these: 138 /// 24. BLOCK_NEEDS_FREE - indicates that the block has been moved 139 /// to malloc'ed memory 140 /// 27. BLOCK_IS_GC - indicates that the block has been moved to 141 /// to GC-allocated memory 142 /// Additionally, the bottom 16 bits are a reference count which 143 /// should be zero on the stack. 144 int flags; 145 146 /// Reserved; should be zero-initialized. 147 int reserved; 148 149 /// Function pointer generated from block literal. 150 _ResultType (*invoke)(Block_literal *, _ParamTypes...); 151 152 /// Block description metadata generated from block literal. 153 struct Block_descriptor *block_descriptor; 154 155 /// Captured values follow. 156 _CapturesTypes captures...; 157 }; 158 */ 159 160 /// The number of fields in a block header. 161 const unsigned BlockHeaderSize = 5; 162 163 namespace { 164 /// A chunk of data that we actually have to capture in the block. 165 struct BlockLayoutChunk { 166 CharUnits Alignment; 167 CharUnits Size; 168 const BlockDecl::Capture *Capture; // null for 'this' 169 llvm::Type *Type; 170 171 BlockLayoutChunk(CharUnits align, CharUnits size, 172 const BlockDecl::Capture *capture, 173 llvm::Type *type) 174 : Alignment(align), Size(size), Capture(capture), Type(type) {} 175 176 /// Tell the block info that this chunk has the given field index. 177 void setIndex(CGBlockInfo &info, unsigned index) { 178 if (!Capture) 179 info.CXXThisIndex = index; 180 else 181 info.Captures[Capture->getVariable()] 182 = CGBlockInfo::Capture::makeIndex(index); 183 } 184 }; 185 186 /// Order by descending alignment. 187 bool operator<(const BlockLayoutChunk &left, const BlockLayoutChunk &right) { 188 return left.Alignment > right.Alignment; 189 } 190 } 191 192 /// Determines if the given type is safe for constant capture in C++. 193 static bool isSafeForCXXConstantCapture(QualType type) { 194 const RecordType *recordType = 195 type->getBaseElementTypeUnsafe()->getAs<RecordType>(); 196 197 // Only records can be unsafe. 198 if (!recordType) return true; 199 200 const CXXRecordDecl *record = cast<CXXRecordDecl>(recordType->getDecl()); 201 202 // Maintain semantics for classes with non-trivial dtors or copy ctors. 203 if (!record->hasTrivialDestructor()) return false; 204 if (!record->hasTrivialCopyConstructor()) return false; 205 206 // Otherwise, we just have to make sure there aren't any mutable 207 // fields that might have changed since initialization. 208 return !record->hasMutableFields(); 209 } 210 211 /// It is illegal to modify a const object after initialization. 212 /// Therefore, if a const object has a constant initializer, we don't 213 /// actually need to keep storage for it in the block; we'll just 214 /// rematerialize it at the start of the block function. This is 215 /// acceptable because we make no promises about address stability of 216 /// captured variables. 217 static llvm::Constant *tryCaptureAsConstant(CodeGenModule &CGM, 218 CodeGenFunction *CGF, 219 const VarDecl *var) { 220 QualType type = var->getType(); 221 222 // We can only do this if the variable is const. 223 if (!type.isConstQualified()) return 0; 224 225 // Furthermore, in C++ we have to worry about mutable fields: 226 // C++ [dcl.type.cv]p4: 227 // Except that any class member declared mutable can be 228 // modified, any attempt to modify a const object during its 229 // lifetime results in undefined behavior. 230 if (CGM.getLangOpts().CPlusPlus && !isSafeForCXXConstantCapture(type)) 231 return 0; 232 233 // If the variable doesn't have any initializer (shouldn't this be 234 // invalid?), it's not clear what we should do. Maybe capture as 235 // zero? 236 const Expr *init = var->getInit(); 237 if (!init) return 0; 238 239 return CGM.EmitConstantInit(*var, CGF); 240 } 241 242 /// Get the low bit of a nonzero character count. This is the 243 /// alignment of the nth byte if the 0th byte is universally aligned. 244 static CharUnits getLowBit(CharUnits v) { 245 return CharUnits::fromQuantity(v.getQuantity() & (~v.getQuantity() + 1)); 246 } 247 248 static void initializeForBlockHeader(CodeGenModule &CGM, CGBlockInfo &info, 249 SmallVectorImpl<llvm::Type*> &elementTypes) { 250 ASTContext &C = CGM.getContext(); 251 252 // The header is basically a 'struct { void *; int; int; void *; void *; }'. 253 CharUnits ptrSize, ptrAlign, intSize, intAlign; 254 llvm::tie(ptrSize, ptrAlign) = C.getTypeInfoInChars(C.VoidPtrTy); 255 llvm::tie(intSize, intAlign) = C.getTypeInfoInChars(C.IntTy); 256 257 // Are there crazy embedded platforms where this isn't true? 258 assert(intSize <= ptrSize && "layout assumptions horribly violated"); 259 260 CharUnits headerSize = ptrSize; 261 if (2 * intSize < ptrAlign) headerSize += ptrSize; 262 else headerSize += 2 * intSize; 263 headerSize += 2 * ptrSize; 264 265 info.BlockAlign = ptrAlign; 266 info.BlockSize = headerSize; 267 268 assert(elementTypes.empty()); 269 llvm::Type *i8p = CGM.getTypes().ConvertType(C.VoidPtrTy); 270 llvm::Type *intTy = CGM.getTypes().ConvertType(C.IntTy); 271 elementTypes.push_back(i8p); 272 elementTypes.push_back(intTy); 273 elementTypes.push_back(intTy); 274 elementTypes.push_back(i8p); 275 elementTypes.push_back(CGM.getBlockDescriptorType()); 276 277 assert(elementTypes.size() == BlockHeaderSize); 278 } 279 280 /// Compute the layout of the given block. Attempts to lay the block 281 /// out with minimal space requirements. 282 static void computeBlockInfo(CodeGenModule &CGM, CodeGenFunction *CGF, 283 CGBlockInfo &info) { 284 ASTContext &C = CGM.getContext(); 285 const BlockDecl *block = info.getBlockDecl(); 286 287 SmallVector<llvm::Type*, 8> elementTypes; 288 initializeForBlockHeader(CGM, info, elementTypes); 289 290 if (!block->hasCaptures()) { 291 info.StructureType = 292 llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true); 293 info.CanBeGlobal = true; 294 return; 295 } 296 297 // Collect the layout chunks. 298 SmallVector<BlockLayoutChunk, 16> layout; 299 layout.reserve(block->capturesCXXThis() + 300 (block->capture_end() - block->capture_begin())); 301 302 CharUnits maxFieldAlign; 303 304 // First, 'this'. 305 if (block->capturesCXXThis()) { 306 const DeclContext *DC = block->getDeclContext(); 307 for (; isa<BlockDecl>(DC); DC = cast<BlockDecl>(DC)->getDeclContext()) 308 ; 309 QualType thisType; 310 if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(DC)) 311 thisType = C.getPointerType(C.getRecordType(RD)); 312 else 313 thisType = cast<CXXMethodDecl>(DC)->getThisType(C); 314 315 llvm::Type *llvmType = CGM.getTypes().ConvertType(thisType); 316 std::pair<CharUnits,CharUnits> tinfo 317 = CGM.getContext().getTypeInfoInChars(thisType); 318 maxFieldAlign = std::max(maxFieldAlign, tinfo.second); 319 320 layout.push_back(BlockLayoutChunk(tinfo.second, tinfo.first, 0, llvmType)); 321 } 322 323 // Next, all the block captures. 324 for (BlockDecl::capture_const_iterator ci = block->capture_begin(), 325 ce = block->capture_end(); ci != ce; ++ci) { 326 const VarDecl *variable = ci->getVariable(); 327 328 if (ci->isByRef()) { 329 // We have to copy/dispose of the __block reference. 330 info.NeedsCopyDispose = true; 331 332 // Just use void* instead of a pointer to the byref type. 333 QualType byRefPtrTy = C.VoidPtrTy; 334 335 llvm::Type *llvmType = CGM.getTypes().ConvertType(byRefPtrTy); 336 std::pair<CharUnits,CharUnits> tinfo 337 = CGM.getContext().getTypeInfoInChars(byRefPtrTy); 338 maxFieldAlign = std::max(maxFieldAlign, tinfo.second); 339 340 layout.push_back(BlockLayoutChunk(tinfo.second, tinfo.first, 341 &*ci, llvmType)); 342 continue; 343 } 344 345 // Otherwise, build a layout chunk with the size and alignment of 346 // the declaration. 347 if (llvm::Constant *constant = tryCaptureAsConstant(CGM, CGF, variable)) { 348 info.Captures[variable] = CGBlockInfo::Capture::makeConstant(constant); 349 continue; 350 } 351 352 // If we have a lifetime qualifier, honor it for capture purposes. 353 // That includes *not* copying it if it's __unsafe_unretained. 354 if (Qualifiers::ObjCLifetime lifetime 355 = variable->getType().getObjCLifetime()) { 356 switch (lifetime) { 357 case Qualifiers::OCL_None: llvm_unreachable("impossible"); 358 case Qualifiers::OCL_ExplicitNone: 359 case Qualifiers::OCL_Autoreleasing: 360 break; 361 362 case Qualifiers::OCL_Strong: 363 case Qualifiers::OCL_Weak: 364 info.NeedsCopyDispose = true; 365 } 366 367 // Block pointers require copy/dispose. So do Objective-C pointers. 368 } else if (variable->getType()->isObjCRetainableType()) { 369 info.NeedsCopyDispose = true; 370 371 // So do types that require non-trivial copy construction. 372 } else if (ci->hasCopyExpr()) { 373 info.NeedsCopyDispose = true; 374 info.HasCXXObject = true; 375 376 // And so do types with destructors. 377 } else if (CGM.getLangOpts().CPlusPlus) { 378 if (const CXXRecordDecl *record = 379 variable->getType()->getAsCXXRecordDecl()) { 380 if (!record->hasTrivialDestructor()) { 381 info.HasCXXObject = true; 382 info.NeedsCopyDispose = true; 383 } 384 } 385 } 386 387 QualType VT = variable->getType(); 388 CharUnits size = C.getTypeSizeInChars(VT); 389 CharUnits align = C.getDeclAlign(variable); 390 391 maxFieldAlign = std::max(maxFieldAlign, align); 392 393 llvm::Type *llvmType = 394 CGM.getTypes().ConvertTypeForMem(VT); 395 396 layout.push_back(BlockLayoutChunk(align, size, &*ci, llvmType)); 397 } 398 399 // If that was everything, we're done here. 400 if (layout.empty()) { 401 info.StructureType = 402 llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true); 403 info.CanBeGlobal = true; 404 return; 405 } 406 407 // Sort the layout by alignment. We have to use a stable sort here 408 // to get reproducible results. There should probably be an 409 // llvm::array_pod_stable_sort. 410 std::stable_sort(layout.begin(), layout.end()); 411 412 CharUnits &blockSize = info.BlockSize; 413 info.BlockAlign = std::max(maxFieldAlign, info.BlockAlign); 414 415 // Assuming that the first byte in the header is maximally aligned, 416 // get the alignment of the first byte following the header. 417 CharUnits endAlign = getLowBit(blockSize); 418 419 // If the end of the header isn't satisfactorily aligned for the 420 // maximum thing, look for things that are okay with the header-end 421 // alignment, and keep appending them until we get something that's 422 // aligned right. This algorithm is only guaranteed optimal if 423 // that condition is satisfied at some point; otherwise we can get 424 // things like: 425 // header // next byte has alignment 4 426 // something_with_size_5; // next byte has alignment 1 427 // something_with_alignment_8; 428 // which has 7 bytes of padding, as opposed to the naive solution 429 // which might have less (?). 430 if (endAlign < maxFieldAlign) { 431 SmallVectorImpl<BlockLayoutChunk>::iterator 432 li = layout.begin() + 1, le = layout.end(); 433 434 // Look for something that the header end is already 435 // satisfactorily aligned for. 436 for (; li != le && endAlign < li->Alignment; ++li) 437 ; 438 439 // If we found something that's naturally aligned for the end of 440 // the header, keep adding things... 441 if (li != le) { 442 SmallVectorImpl<BlockLayoutChunk>::iterator first = li; 443 for (; li != le; ++li) { 444 assert(endAlign >= li->Alignment); 445 446 li->setIndex(info, elementTypes.size()); 447 elementTypes.push_back(li->Type); 448 blockSize += li->Size; 449 endAlign = getLowBit(blockSize); 450 451 // ...until we get to the alignment of the maximum field. 452 if (endAlign >= maxFieldAlign) 453 break; 454 } 455 456 // Don't re-append everything we just appended. 457 layout.erase(first, li); 458 } 459 } 460 461 assert(endAlign == getLowBit(blockSize)); 462 463 // At this point, we just have to add padding if the end align still 464 // isn't aligned right. 465 if (endAlign < maxFieldAlign) { 466 CharUnits newBlockSize = blockSize.RoundUpToAlignment(maxFieldAlign); 467 CharUnits padding = newBlockSize - blockSize; 468 469 elementTypes.push_back(llvm::ArrayType::get(CGM.Int8Ty, 470 padding.getQuantity())); 471 blockSize = newBlockSize; 472 endAlign = getLowBit(blockSize); // might be > maxFieldAlign 473 } 474 475 assert(endAlign >= maxFieldAlign); 476 assert(endAlign == getLowBit(blockSize)); 477 478 // Slam everything else on now. This works because they have 479 // strictly decreasing alignment and we expect that size is always a 480 // multiple of alignment. 481 for (SmallVectorImpl<BlockLayoutChunk>::iterator 482 li = layout.begin(), le = layout.end(); li != le; ++li) { 483 assert(endAlign >= li->Alignment); 484 li->setIndex(info, elementTypes.size()); 485 elementTypes.push_back(li->Type); 486 blockSize += li->Size; 487 endAlign = getLowBit(blockSize); 488 } 489 490 info.StructureType = 491 llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true); 492 } 493 494 /// Enter the scope of a block. This should be run at the entrance to 495 /// a full-expression so that the block's cleanups are pushed at the 496 /// right place in the stack. 497 static void enterBlockScope(CodeGenFunction &CGF, BlockDecl *block) { 498 assert(CGF.HaveInsertPoint()); 499 500 // Allocate the block info and place it at the head of the list. 501 CGBlockInfo &blockInfo = 502 *new CGBlockInfo(block, CGF.CurFn->getName()); 503 blockInfo.NextBlockInfo = CGF.FirstBlockInfo; 504 CGF.FirstBlockInfo = &blockInfo; 505 506 // Compute information about the layout, etc., of this block, 507 // pushing cleanups as necessary. 508 computeBlockInfo(CGF.CGM, &CGF, blockInfo); 509 510 // Nothing else to do if it can be global. 511 if (blockInfo.CanBeGlobal) return; 512 513 // Make the allocation for the block. 514 blockInfo.Address = 515 CGF.CreateTempAlloca(blockInfo.StructureType, "block"); 516 blockInfo.Address->setAlignment(blockInfo.BlockAlign.getQuantity()); 517 518 // If there are cleanups to emit, enter them (but inactive). 519 if (!blockInfo.NeedsCopyDispose) return; 520 521 // Walk through the captures (in order) and find the ones not 522 // captured by constant. 523 for (BlockDecl::capture_const_iterator ci = block->capture_begin(), 524 ce = block->capture_end(); ci != ce; ++ci) { 525 // Ignore __block captures; there's nothing special in the 526 // on-stack block that we need to do for them. 527 if (ci->isByRef()) continue; 528 529 // Ignore variables that are constant-captured. 530 const VarDecl *variable = ci->getVariable(); 531 CGBlockInfo::Capture &capture = blockInfo.getCapture(variable); 532 if (capture.isConstant()) continue; 533 534 // Ignore objects that aren't destructed. 535 QualType::DestructionKind dtorKind = 536 variable->getType().isDestructedType(); 537 if (dtorKind == QualType::DK_none) continue; 538 539 CodeGenFunction::Destroyer *destroyer; 540 541 // Block captures count as local values and have imprecise semantics. 542 // They also can't be arrays, so need to worry about that. 543 if (dtorKind == QualType::DK_objc_strong_lifetime) { 544 destroyer = CodeGenFunction::destroyARCStrongImprecise; 545 } else { 546 destroyer = CGF.getDestroyer(dtorKind); 547 } 548 549 // GEP down to the address. 550 llvm::Value *addr = CGF.Builder.CreateStructGEP(blockInfo.Address, 551 capture.getIndex()); 552 553 // We can use that GEP as the dominating IP. 554 if (!blockInfo.DominatingIP) 555 blockInfo.DominatingIP = cast<llvm::Instruction>(addr); 556 557 CleanupKind cleanupKind = InactiveNormalCleanup; 558 bool useArrayEHCleanup = CGF.needsEHCleanup(dtorKind); 559 if (useArrayEHCleanup) 560 cleanupKind = InactiveNormalAndEHCleanup; 561 562 CGF.pushDestroy(cleanupKind, addr, variable->getType(), 563 destroyer, useArrayEHCleanup); 564 565 // Remember where that cleanup was. 566 capture.setCleanup(CGF.EHStack.stable_begin()); 567 } 568 } 569 570 /// Enter a full-expression with a non-trivial number of objects to 571 /// clean up. This is in this file because, at the moment, the only 572 /// kind of cleanup object is a BlockDecl*. 573 void CodeGenFunction::enterNonTrivialFullExpression(const ExprWithCleanups *E) { 574 assert(E->getNumObjects() != 0); 575 ArrayRef<ExprWithCleanups::CleanupObject> cleanups = E->getObjects(); 576 for (ArrayRef<ExprWithCleanups::CleanupObject>::iterator 577 i = cleanups.begin(), e = cleanups.end(); i != e; ++i) { 578 enterBlockScope(*this, *i); 579 } 580 } 581 582 /// Find the layout for the given block in a linked list and remove it. 583 static CGBlockInfo *findAndRemoveBlockInfo(CGBlockInfo **head, 584 const BlockDecl *block) { 585 while (true) { 586 assert(head && *head); 587 CGBlockInfo *cur = *head; 588 589 // If this is the block we're looking for, splice it out of the list. 590 if (cur->getBlockDecl() == block) { 591 *head = cur->NextBlockInfo; 592 return cur; 593 } 594 595 head = &cur->NextBlockInfo; 596 } 597 } 598 599 /// Destroy a chain of block layouts. 600 void CodeGenFunction::destroyBlockInfos(CGBlockInfo *head) { 601 assert(head && "destroying an empty chain"); 602 do { 603 CGBlockInfo *cur = head; 604 head = cur->NextBlockInfo; 605 delete cur; 606 } while (head != 0); 607 } 608 609 /// Emit a block literal expression in the current function. 610 llvm::Value *CodeGenFunction::EmitBlockLiteral(const BlockExpr *blockExpr) { 611 // If the block has no captures, we won't have a pre-computed 612 // layout for it. 613 if (!blockExpr->getBlockDecl()->hasCaptures()) { 614 CGBlockInfo blockInfo(blockExpr->getBlockDecl(), CurFn->getName()); 615 computeBlockInfo(CGM, this, blockInfo); 616 blockInfo.BlockExpression = blockExpr; 617 return EmitBlockLiteral(blockInfo); 618 } 619 620 // Find the block info for this block and take ownership of it. 621 OwningPtr<CGBlockInfo> blockInfo; 622 blockInfo.reset(findAndRemoveBlockInfo(&FirstBlockInfo, 623 blockExpr->getBlockDecl())); 624 625 blockInfo->BlockExpression = blockExpr; 626 return EmitBlockLiteral(*blockInfo); 627 } 628 629 llvm::Value *CodeGenFunction::EmitBlockLiteral(const CGBlockInfo &blockInfo) { 630 // Using the computed layout, generate the actual block function. 631 bool isLambdaConv = blockInfo.getBlockDecl()->isConversionFromLambda(); 632 llvm::Constant *blockFn 633 = CodeGenFunction(CGM, true).GenerateBlockFunction(CurGD, blockInfo, 634 CurFuncDecl, LocalDeclMap, 635 isLambdaConv); 636 blockFn = llvm::ConstantExpr::getBitCast(blockFn, VoidPtrTy); 637 638 // If there is nothing to capture, we can emit this as a global block. 639 if (blockInfo.CanBeGlobal) 640 return buildGlobalBlock(CGM, blockInfo, blockFn); 641 642 // Otherwise, we have to emit this as a local block. 643 644 llvm::Constant *isa = CGM.getNSConcreteStackBlock(); 645 isa = llvm::ConstantExpr::getBitCast(isa, VoidPtrTy); 646 647 // Build the block descriptor. 648 llvm::Constant *descriptor = buildBlockDescriptor(CGM, blockInfo); 649 650 llvm::AllocaInst *blockAddr = blockInfo.Address; 651 assert(blockAddr && "block has no address!"); 652 653 // Compute the initial on-stack block flags. 654 BlockFlags flags = BLOCK_HAS_SIGNATURE; 655 if (blockInfo.NeedsCopyDispose) flags |= BLOCK_HAS_COPY_DISPOSE; 656 if (blockInfo.HasCXXObject) flags |= BLOCK_HAS_CXX_OBJ; 657 if (blockInfo.UsesStret) flags |= BLOCK_USE_STRET; 658 659 // Initialize the block literal. 660 Builder.CreateStore(isa, Builder.CreateStructGEP(blockAddr, 0, "block.isa")); 661 Builder.CreateStore(llvm::ConstantInt::get(IntTy, flags.getBitMask()), 662 Builder.CreateStructGEP(blockAddr, 1, "block.flags")); 663 Builder.CreateStore(llvm::ConstantInt::get(IntTy, 0), 664 Builder.CreateStructGEP(blockAddr, 2, "block.reserved")); 665 Builder.CreateStore(blockFn, Builder.CreateStructGEP(blockAddr, 3, 666 "block.invoke")); 667 Builder.CreateStore(descriptor, Builder.CreateStructGEP(blockAddr, 4, 668 "block.descriptor")); 669 670 // Finally, capture all the values into the block. 671 const BlockDecl *blockDecl = blockInfo.getBlockDecl(); 672 673 // First, 'this'. 674 if (blockDecl->capturesCXXThis()) { 675 llvm::Value *addr = Builder.CreateStructGEP(blockAddr, 676 blockInfo.CXXThisIndex, 677 "block.captured-this.addr"); 678 Builder.CreateStore(LoadCXXThis(), addr); 679 } 680 681 // Next, captured variables. 682 for (BlockDecl::capture_const_iterator ci = blockDecl->capture_begin(), 683 ce = blockDecl->capture_end(); ci != ce; ++ci) { 684 const VarDecl *variable = ci->getVariable(); 685 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable); 686 687 // Ignore constant captures. 688 if (capture.isConstant()) continue; 689 690 QualType type = variable->getType(); 691 692 // This will be a [[type]]*, except that a byref entry will just be 693 // an i8**. 694 llvm::Value *blockField = 695 Builder.CreateStructGEP(blockAddr, capture.getIndex(), 696 "block.captured"); 697 698 // Compute the address of the thing we're going to move into the 699 // block literal. 700 llvm::Value *src; 701 if (BlockInfo && ci->isNested()) { 702 // We need to use the capture from the enclosing block. 703 const CGBlockInfo::Capture &enclosingCapture = 704 BlockInfo->getCapture(variable); 705 706 // This is a [[type]]*, except that a byref entry wil just be an i8**. 707 src = Builder.CreateStructGEP(LoadBlockStruct(), 708 enclosingCapture.getIndex(), 709 "block.capture.addr"); 710 } else if (blockDecl->isConversionFromLambda()) { 711 // The lambda capture in a lambda's conversion-to-block-pointer is 712 // special; we'll simply emit it directly. 713 src = 0; 714 } else { 715 // This is a [[type]]*. 716 src = LocalDeclMap[variable]; 717 } 718 719 // For byrefs, we just write the pointer to the byref struct into 720 // the block field. There's no need to chase the forwarding 721 // pointer at this point, since we're building something that will 722 // live a shorter life than the stack byref anyway. 723 if (ci->isByRef()) { 724 // Get a void* that points to the byref struct. 725 if (ci->isNested()) 726 src = Builder.CreateLoad(src, "byref.capture"); 727 else 728 src = Builder.CreateBitCast(src, VoidPtrTy); 729 730 // Write that void* into the capture field. 731 Builder.CreateStore(src, blockField); 732 733 // If we have a copy constructor, evaluate that into the block field. 734 } else if (const Expr *copyExpr = ci->getCopyExpr()) { 735 if (blockDecl->isConversionFromLambda()) { 736 // If we have a lambda conversion, emit the expression 737 // directly into the block instead. 738 CharUnits Align = getContext().getTypeAlignInChars(type); 739 AggValueSlot Slot = 740 AggValueSlot::forAddr(blockField, Align, Qualifiers(), 741 AggValueSlot::IsDestructed, 742 AggValueSlot::DoesNotNeedGCBarriers, 743 AggValueSlot::IsNotAliased); 744 EmitAggExpr(copyExpr, Slot); 745 } else { 746 EmitSynthesizedCXXCopyCtor(blockField, src, copyExpr); 747 } 748 749 // If it's a reference variable, copy the reference into the block field. 750 } else if (type->isReferenceType()) { 751 Builder.CreateStore(Builder.CreateLoad(src, "ref.val"), blockField); 752 753 // Otherwise, fake up a POD copy into the block field. 754 } else { 755 // Fake up a new variable so that EmitScalarInit doesn't think 756 // we're referring to the variable in its own initializer. 757 ImplicitParamDecl blockFieldPseudoVar(/*DC*/ 0, SourceLocation(), 758 /*name*/ 0, type); 759 760 // We use one of these or the other depending on whether the 761 // reference is nested. 762 DeclRefExpr declRef(const_cast<VarDecl*>(variable), 763 /*refersToEnclosing*/ ci->isNested(), type, 764 VK_LValue, SourceLocation()); 765 766 ImplicitCastExpr l2r(ImplicitCastExpr::OnStack, type, CK_LValueToRValue, 767 &declRef, VK_RValue); 768 EmitExprAsInit(&l2r, &blockFieldPseudoVar, 769 MakeAddrLValue(blockField, type, 770 getContext().getDeclAlign(variable)), 771 /*captured by init*/ false); 772 } 773 774 // Activate the cleanup if layout pushed one. 775 if (!ci->isByRef()) { 776 EHScopeStack::stable_iterator cleanup = capture.getCleanup(); 777 if (cleanup.isValid()) 778 ActivateCleanupBlock(cleanup, blockInfo.DominatingIP); 779 } 780 } 781 782 // Cast to the converted block-pointer type, which happens (somewhat 783 // unfortunately) to be a pointer to function type. 784 llvm::Value *result = 785 Builder.CreateBitCast(blockAddr, 786 ConvertType(blockInfo.getBlockExpr()->getType())); 787 788 return result; 789 } 790 791 792 llvm::Type *CodeGenModule::getBlockDescriptorType() { 793 if (BlockDescriptorType) 794 return BlockDescriptorType; 795 796 llvm::Type *UnsignedLongTy = 797 getTypes().ConvertType(getContext().UnsignedLongTy); 798 799 // struct __block_descriptor { 800 // unsigned long reserved; 801 // unsigned long block_size; 802 // 803 // // later, the following will be added 804 // 805 // struct { 806 // void (*copyHelper)(); 807 // void (*copyHelper)(); 808 // } helpers; // !!! optional 809 // 810 // const char *signature; // the block signature 811 // const char *layout; // reserved 812 // }; 813 BlockDescriptorType = 814 llvm::StructType::create("struct.__block_descriptor", 815 UnsignedLongTy, UnsignedLongTy, NULL); 816 817 // Now form a pointer to that. 818 BlockDescriptorType = llvm::PointerType::getUnqual(BlockDescriptorType); 819 return BlockDescriptorType; 820 } 821 822 llvm::Type *CodeGenModule::getGenericBlockLiteralType() { 823 if (GenericBlockLiteralType) 824 return GenericBlockLiteralType; 825 826 llvm::Type *BlockDescPtrTy = getBlockDescriptorType(); 827 828 // struct __block_literal_generic { 829 // void *__isa; 830 // int __flags; 831 // int __reserved; 832 // void (*__invoke)(void *); 833 // struct __block_descriptor *__descriptor; 834 // }; 835 GenericBlockLiteralType = 836 llvm::StructType::create("struct.__block_literal_generic", 837 VoidPtrTy, IntTy, IntTy, VoidPtrTy, 838 BlockDescPtrTy, NULL); 839 840 return GenericBlockLiteralType; 841 } 842 843 844 RValue CodeGenFunction::EmitBlockCallExpr(const CallExpr* E, 845 ReturnValueSlot ReturnValue) { 846 const BlockPointerType *BPT = 847 E->getCallee()->getType()->getAs<BlockPointerType>(); 848 849 llvm::Value *Callee = EmitScalarExpr(E->getCallee()); 850 851 // Get a pointer to the generic block literal. 852 llvm::Type *BlockLiteralTy = 853 llvm::PointerType::getUnqual(CGM.getGenericBlockLiteralType()); 854 855 // Bitcast the callee to a block literal. 856 llvm::Value *BlockLiteral = 857 Builder.CreateBitCast(Callee, BlockLiteralTy, "block.literal"); 858 859 // Get the function pointer from the literal. 860 llvm::Value *FuncPtr = Builder.CreateStructGEP(BlockLiteral, 3); 861 862 BlockLiteral = Builder.CreateBitCast(BlockLiteral, VoidPtrTy); 863 864 // Add the block literal. 865 CallArgList Args; 866 Args.add(RValue::get(BlockLiteral), getContext().VoidPtrTy); 867 868 QualType FnType = BPT->getPointeeType(); 869 870 // And the rest of the arguments. 871 EmitCallArgs(Args, FnType->getAs<FunctionProtoType>(), 872 E->arg_begin(), E->arg_end()); 873 874 // Load the function. 875 llvm::Value *Func = Builder.CreateLoad(FuncPtr); 876 877 const FunctionType *FuncTy = FnType->castAs<FunctionType>(); 878 const CGFunctionInfo &FnInfo = 879 CGM.getTypes().arrangeFreeFunctionCall(Args, FuncTy); 880 881 // Cast the function pointer to the right type. 882 llvm::Type *BlockFTy = CGM.getTypes().GetFunctionType(FnInfo); 883 884 llvm::Type *BlockFTyPtr = llvm::PointerType::getUnqual(BlockFTy); 885 Func = Builder.CreateBitCast(Func, BlockFTyPtr); 886 887 // And call the block. 888 return EmitCall(FnInfo, Func, ReturnValue, Args); 889 } 890 891 llvm::Value *CodeGenFunction::GetAddrOfBlockDecl(const VarDecl *variable, 892 bool isByRef) { 893 assert(BlockInfo && "evaluating block ref without block information?"); 894 const CGBlockInfo::Capture &capture = BlockInfo->getCapture(variable); 895 896 // Handle constant captures. 897 if (capture.isConstant()) return LocalDeclMap[variable]; 898 899 llvm::Value *addr = 900 Builder.CreateStructGEP(LoadBlockStruct(), capture.getIndex(), 901 "block.capture.addr"); 902 903 if (isByRef) { 904 // addr should be a void** right now. Load, then cast the result 905 // to byref*. 906 907 addr = Builder.CreateLoad(addr); 908 llvm::PointerType *byrefPointerType 909 = llvm::PointerType::get(BuildByRefType(variable), 0); 910 addr = Builder.CreateBitCast(addr, byrefPointerType, 911 "byref.addr"); 912 913 // Follow the forwarding pointer. 914 addr = Builder.CreateStructGEP(addr, 1, "byref.forwarding"); 915 addr = Builder.CreateLoad(addr, "byref.addr.forwarded"); 916 917 // Cast back to byref* and GEP over to the actual object. 918 addr = Builder.CreateBitCast(addr, byrefPointerType); 919 addr = Builder.CreateStructGEP(addr, getByRefValueLLVMField(variable), 920 variable->getNameAsString()); 921 } 922 923 if (variable->getType()->isReferenceType()) 924 addr = Builder.CreateLoad(addr, "ref.tmp"); 925 926 return addr; 927 } 928 929 llvm::Constant * 930 CodeGenModule::GetAddrOfGlobalBlock(const BlockExpr *blockExpr, 931 const char *name) { 932 CGBlockInfo blockInfo(blockExpr->getBlockDecl(), name); 933 blockInfo.BlockExpression = blockExpr; 934 935 // Compute information about the layout, etc., of this block. 936 computeBlockInfo(*this, 0, blockInfo); 937 938 // Using that metadata, generate the actual block function. 939 llvm::Constant *blockFn; 940 { 941 llvm::DenseMap<const Decl*, llvm::Value*> LocalDeclMap; 942 blockFn = CodeGenFunction(*this).GenerateBlockFunction(GlobalDecl(), 943 blockInfo, 944 0, LocalDeclMap, 945 false); 946 } 947 blockFn = llvm::ConstantExpr::getBitCast(blockFn, VoidPtrTy); 948 949 return buildGlobalBlock(*this, blockInfo, blockFn); 950 } 951 952 static llvm::Constant *buildGlobalBlock(CodeGenModule &CGM, 953 const CGBlockInfo &blockInfo, 954 llvm::Constant *blockFn) { 955 assert(blockInfo.CanBeGlobal); 956 957 // Generate the constants for the block literal initializer. 958 llvm::Constant *fields[BlockHeaderSize]; 959 960 // isa 961 fields[0] = CGM.getNSConcreteGlobalBlock(); 962 963 // __flags 964 BlockFlags flags = BLOCK_IS_GLOBAL | BLOCK_HAS_SIGNATURE; 965 if (blockInfo.UsesStret) flags |= BLOCK_USE_STRET; 966 967 fields[1] = llvm::ConstantInt::get(CGM.IntTy, flags.getBitMask()); 968 969 // Reserved 970 fields[2] = llvm::Constant::getNullValue(CGM.IntTy); 971 972 // Function 973 fields[3] = blockFn; 974 975 // Descriptor 976 fields[4] = buildBlockDescriptor(CGM, blockInfo); 977 978 llvm::Constant *init = llvm::ConstantStruct::getAnon(fields); 979 980 llvm::GlobalVariable *literal = 981 new llvm::GlobalVariable(CGM.getModule(), 982 init->getType(), 983 /*constant*/ true, 984 llvm::GlobalVariable::InternalLinkage, 985 init, 986 "__block_literal_global"); 987 literal->setAlignment(blockInfo.BlockAlign.getQuantity()); 988 989 // Return a constant of the appropriately-casted type. 990 llvm::Type *requiredType = 991 CGM.getTypes().ConvertType(blockInfo.getBlockExpr()->getType()); 992 return llvm::ConstantExpr::getBitCast(literal, requiredType); 993 } 994 995 llvm::Function * 996 CodeGenFunction::GenerateBlockFunction(GlobalDecl GD, 997 const CGBlockInfo &blockInfo, 998 const Decl *outerFnDecl, 999 const DeclMapTy &ldm, 1000 bool IsLambdaConversionToBlock) { 1001 const BlockDecl *blockDecl = blockInfo.getBlockDecl(); 1002 1003 // Check if we should generate debug info for this block function. 1004 if (CGM.getModuleDebugInfo()) 1005 DebugInfo = CGM.getModuleDebugInfo(); 1006 CurGD = GD; 1007 1008 BlockInfo = &blockInfo; 1009 1010 // Arrange for local static and local extern declarations to appear 1011 // to be local to this function as well, in case they're directly 1012 // referenced in a block. 1013 for (DeclMapTy::const_iterator i = ldm.begin(), e = ldm.end(); i != e; ++i) { 1014 const VarDecl *var = dyn_cast<VarDecl>(i->first); 1015 if (var && !var->hasLocalStorage()) 1016 LocalDeclMap[var] = i->second; 1017 } 1018 1019 // Begin building the function declaration. 1020 1021 // Build the argument list. 1022 FunctionArgList args; 1023 1024 // The first argument is the block pointer. Just take it as a void* 1025 // and cast it later. 1026 QualType selfTy = getContext().VoidPtrTy; 1027 IdentifierInfo *II = &CGM.getContext().Idents.get(".block_descriptor"); 1028 1029 ImplicitParamDecl selfDecl(const_cast<BlockDecl*>(blockDecl), 1030 SourceLocation(), II, selfTy); 1031 args.push_back(&selfDecl); 1032 1033 // Now add the rest of the parameters. 1034 for (BlockDecl::param_const_iterator i = blockDecl->param_begin(), 1035 e = blockDecl->param_end(); i != e; ++i) 1036 args.push_back(*i); 1037 1038 // Create the function declaration. 1039 const FunctionProtoType *fnType = blockInfo.getBlockExpr()->getFunctionType(); 1040 const CGFunctionInfo &fnInfo = 1041 CGM.getTypes().arrangeFunctionDeclaration(fnType->getResultType(), args, 1042 fnType->getExtInfo(), 1043 fnType->isVariadic()); 1044 if (CGM.ReturnTypeUsesSRet(fnInfo)) 1045 blockInfo.UsesStret = true; 1046 1047 llvm::FunctionType *fnLLVMType = CGM.getTypes().GetFunctionType(fnInfo); 1048 1049 MangleBuffer name; 1050 CGM.getBlockMangledName(GD, name, blockDecl); 1051 llvm::Function *fn = 1052 llvm::Function::Create(fnLLVMType, llvm::GlobalValue::InternalLinkage, 1053 name.getString(), &CGM.getModule()); 1054 CGM.SetInternalFunctionAttributes(blockDecl, fn, fnInfo); 1055 1056 // Begin generating the function. 1057 StartFunction(blockDecl, fnType->getResultType(), fn, fnInfo, args, 1058 blockInfo.getBlockExpr()->getBody()->getLocStart()); 1059 CurFuncDecl = outerFnDecl; // StartFunction sets this to blockDecl 1060 1061 // Okay. Undo some of what StartFunction did. 1062 1063 // Pull the 'self' reference out of the local decl map. 1064 llvm::Value *blockAddr = LocalDeclMap[&selfDecl]; 1065 LocalDeclMap.erase(&selfDecl); 1066 BlockPointer = Builder.CreateBitCast(blockAddr, 1067 blockInfo.StructureType->getPointerTo(), 1068 "block"); 1069 1070 // If we have a C++ 'this' reference, go ahead and force it into 1071 // existence now. 1072 if (blockDecl->capturesCXXThis()) { 1073 llvm::Value *addr = Builder.CreateStructGEP(BlockPointer, 1074 blockInfo.CXXThisIndex, 1075 "block.captured-this"); 1076 CXXThisValue = Builder.CreateLoad(addr, "this"); 1077 } 1078 1079 // LoadObjCSelf() expects there to be an entry for 'self' in LocalDeclMap; 1080 // appease it. 1081 if (const ObjCMethodDecl *method 1082 = dyn_cast_or_null<ObjCMethodDecl>(CurFuncDecl)) { 1083 const VarDecl *self = method->getSelfDecl(); 1084 1085 // There might not be a capture for 'self', but if there is... 1086 if (blockInfo.Captures.count(self)) { 1087 const CGBlockInfo::Capture &capture = blockInfo.getCapture(self); 1088 llvm::Value *selfAddr = Builder.CreateStructGEP(BlockPointer, 1089 capture.getIndex(), 1090 "block.captured-self"); 1091 LocalDeclMap[self] = selfAddr; 1092 } 1093 } 1094 1095 // Also force all the constant captures. 1096 for (BlockDecl::capture_const_iterator ci = blockDecl->capture_begin(), 1097 ce = blockDecl->capture_end(); ci != ce; ++ci) { 1098 const VarDecl *variable = ci->getVariable(); 1099 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable); 1100 if (!capture.isConstant()) continue; 1101 1102 unsigned align = getContext().getDeclAlign(variable).getQuantity(); 1103 1104 llvm::AllocaInst *alloca = 1105 CreateMemTemp(variable->getType(), "block.captured-const"); 1106 alloca->setAlignment(align); 1107 1108 Builder.CreateStore(capture.getConstant(), alloca, align); 1109 1110 LocalDeclMap[variable] = alloca; 1111 } 1112 1113 // Save a spot to insert the debug information for all the DeclRefExprs. 1114 llvm::BasicBlock *entry = Builder.GetInsertBlock(); 1115 llvm::BasicBlock::iterator entry_ptr = Builder.GetInsertPoint(); 1116 --entry_ptr; 1117 1118 if (IsLambdaConversionToBlock) 1119 EmitLambdaBlockInvokeBody(); 1120 else 1121 EmitStmt(blockDecl->getBody()); 1122 1123 // Remember where we were... 1124 llvm::BasicBlock *resume = Builder.GetInsertBlock(); 1125 1126 // Go back to the entry. 1127 ++entry_ptr; 1128 Builder.SetInsertPoint(entry, entry_ptr); 1129 1130 // Emit debug information for all the DeclRefExprs. 1131 // FIXME: also for 'this' 1132 if (CGDebugInfo *DI = getDebugInfo()) { 1133 for (BlockDecl::capture_const_iterator ci = blockDecl->capture_begin(), 1134 ce = blockDecl->capture_end(); ci != ce; ++ci) { 1135 const VarDecl *variable = ci->getVariable(); 1136 DI->EmitLocation(Builder, variable->getLocation()); 1137 1138 if (CGM.getCodeGenOpts().DebugInfo >= CodeGenOptions::LimitedDebugInfo) { 1139 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable); 1140 if (capture.isConstant()) { 1141 DI->EmitDeclareOfAutoVariable(variable, LocalDeclMap[variable], 1142 Builder); 1143 continue; 1144 } 1145 1146 DI->EmitDeclareOfBlockDeclRefVariable(variable, BlockPointer, 1147 Builder, blockInfo); 1148 } 1149 } 1150 } 1151 1152 // And resume where we left off. 1153 if (resume == 0) 1154 Builder.ClearInsertionPoint(); 1155 else 1156 Builder.SetInsertPoint(resume); 1157 1158 FinishFunction(cast<CompoundStmt>(blockDecl->getBody())->getRBracLoc()); 1159 1160 return fn; 1161 } 1162 1163 /* 1164 notes.push_back(HelperInfo()); 1165 HelperInfo ¬e = notes.back(); 1166 note.index = capture.getIndex(); 1167 note.RequiresCopying = (ci->hasCopyExpr() || BlockRequiresCopying(type)); 1168 note.cxxbar_import = ci->getCopyExpr(); 1169 1170 if (ci->isByRef()) { 1171 note.flag = BLOCK_FIELD_IS_BYREF; 1172 if (type.isObjCGCWeak()) 1173 note.flag |= BLOCK_FIELD_IS_WEAK; 1174 } else if (type->isBlockPointerType()) { 1175 note.flag = BLOCK_FIELD_IS_BLOCK; 1176 } else { 1177 note.flag = BLOCK_FIELD_IS_OBJECT; 1178 } 1179 */ 1180 1181 1182 1183 llvm::Constant * 1184 CodeGenFunction::GenerateCopyHelperFunction(const CGBlockInfo &blockInfo) { 1185 ASTContext &C = getContext(); 1186 1187 FunctionArgList args; 1188 ImplicitParamDecl dstDecl(0, SourceLocation(), 0, C.VoidPtrTy); 1189 args.push_back(&dstDecl); 1190 ImplicitParamDecl srcDecl(0, SourceLocation(), 0, C.VoidPtrTy); 1191 args.push_back(&srcDecl); 1192 1193 const CGFunctionInfo &FI = 1194 CGM.getTypes().arrangeFunctionDeclaration(C.VoidTy, args, 1195 FunctionType::ExtInfo(), 1196 /*variadic*/ false); 1197 1198 // FIXME: it would be nice if these were mergeable with things with 1199 // identical semantics. 1200 llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI); 1201 1202 llvm::Function *Fn = 1203 llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage, 1204 "__copy_helper_block_", &CGM.getModule()); 1205 1206 IdentifierInfo *II 1207 = &CGM.getContext().Idents.get("__copy_helper_block_"); 1208 1209 // Check if we should generate debug info for this block helper function. 1210 if (CGM.getModuleDebugInfo()) 1211 DebugInfo = CGM.getModuleDebugInfo(); 1212 1213 FunctionDecl *FD = FunctionDecl::Create(C, 1214 C.getTranslationUnitDecl(), 1215 SourceLocation(), 1216 SourceLocation(), II, C.VoidTy, 0, 1217 SC_Static, 1218 SC_None, 1219 false, 1220 false); 1221 StartFunction(FD, C.VoidTy, Fn, FI, args, SourceLocation()); 1222 1223 llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo(); 1224 1225 llvm::Value *src = GetAddrOfLocalVar(&srcDecl); 1226 src = Builder.CreateLoad(src); 1227 src = Builder.CreateBitCast(src, structPtrTy, "block.source"); 1228 1229 llvm::Value *dst = GetAddrOfLocalVar(&dstDecl); 1230 dst = Builder.CreateLoad(dst); 1231 dst = Builder.CreateBitCast(dst, structPtrTy, "block.dest"); 1232 1233 const BlockDecl *blockDecl = blockInfo.getBlockDecl(); 1234 1235 for (BlockDecl::capture_const_iterator ci = blockDecl->capture_begin(), 1236 ce = blockDecl->capture_end(); ci != ce; ++ci) { 1237 const VarDecl *variable = ci->getVariable(); 1238 QualType type = variable->getType(); 1239 1240 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable); 1241 if (capture.isConstant()) continue; 1242 1243 const Expr *copyExpr = ci->getCopyExpr(); 1244 BlockFieldFlags flags; 1245 1246 bool isARCWeakCapture = false; 1247 1248 if (copyExpr) { 1249 assert(!ci->isByRef()); 1250 // don't bother computing flags 1251 1252 } else if (ci->isByRef()) { 1253 flags = BLOCK_FIELD_IS_BYREF; 1254 if (type.isObjCGCWeak()) 1255 flags |= BLOCK_FIELD_IS_WEAK; 1256 1257 } else if (type->isObjCRetainableType()) { 1258 flags = BLOCK_FIELD_IS_OBJECT; 1259 if (type->isBlockPointerType()) 1260 flags = BLOCK_FIELD_IS_BLOCK; 1261 1262 // Special rules for ARC captures: 1263 if (getLangOpts().ObjCAutoRefCount) { 1264 Qualifiers qs = type.getQualifiers(); 1265 1266 // Don't generate special copy logic for a captured object 1267 // unless it's __strong or __weak. 1268 if (!qs.hasStrongOrWeakObjCLifetime()) 1269 continue; 1270 1271 // Support __weak direct captures. 1272 if (qs.getObjCLifetime() == Qualifiers::OCL_Weak) 1273 isARCWeakCapture = true; 1274 } 1275 } else { 1276 continue; 1277 } 1278 1279 unsigned index = capture.getIndex(); 1280 llvm::Value *srcField = Builder.CreateStructGEP(src, index); 1281 llvm::Value *dstField = Builder.CreateStructGEP(dst, index); 1282 1283 // If there's an explicit copy expression, we do that. 1284 if (copyExpr) { 1285 EmitSynthesizedCXXCopyCtor(dstField, srcField, copyExpr); 1286 } else if (isARCWeakCapture) { 1287 EmitARCCopyWeak(dstField, srcField); 1288 } else { 1289 llvm::Value *srcValue = Builder.CreateLoad(srcField, "blockcopy.src"); 1290 srcValue = Builder.CreateBitCast(srcValue, VoidPtrTy); 1291 llvm::Value *dstAddr = Builder.CreateBitCast(dstField, VoidPtrTy); 1292 Builder.CreateCall3(CGM.getBlockObjectAssign(), dstAddr, srcValue, 1293 llvm::ConstantInt::get(Int32Ty, flags.getBitMask())); 1294 } 1295 } 1296 1297 FinishFunction(); 1298 1299 return llvm::ConstantExpr::getBitCast(Fn, VoidPtrTy); 1300 } 1301 1302 llvm::Constant * 1303 CodeGenFunction::GenerateDestroyHelperFunction(const CGBlockInfo &blockInfo) { 1304 ASTContext &C = getContext(); 1305 1306 FunctionArgList args; 1307 ImplicitParamDecl srcDecl(0, SourceLocation(), 0, C.VoidPtrTy); 1308 args.push_back(&srcDecl); 1309 1310 const CGFunctionInfo &FI = 1311 CGM.getTypes().arrangeFunctionDeclaration(C.VoidTy, args, 1312 FunctionType::ExtInfo(), 1313 /*variadic*/ false); 1314 1315 // FIXME: We'd like to put these into a mergable by content, with 1316 // internal linkage. 1317 llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI); 1318 1319 llvm::Function *Fn = 1320 llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage, 1321 "__destroy_helper_block_", &CGM.getModule()); 1322 1323 // Check if we should generate debug info for this block destroy function. 1324 if (CGM.getModuleDebugInfo()) 1325 DebugInfo = CGM.getModuleDebugInfo(); 1326 1327 IdentifierInfo *II 1328 = &CGM.getContext().Idents.get("__destroy_helper_block_"); 1329 1330 FunctionDecl *FD = FunctionDecl::Create(C, C.getTranslationUnitDecl(), 1331 SourceLocation(), 1332 SourceLocation(), II, C.VoidTy, 0, 1333 SC_Static, 1334 SC_None, 1335 false, false); 1336 StartFunction(FD, C.VoidTy, Fn, FI, args, SourceLocation()); 1337 1338 llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo(); 1339 1340 llvm::Value *src = GetAddrOfLocalVar(&srcDecl); 1341 src = Builder.CreateLoad(src); 1342 src = Builder.CreateBitCast(src, structPtrTy, "block"); 1343 1344 const BlockDecl *blockDecl = blockInfo.getBlockDecl(); 1345 1346 CodeGenFunction::RunCleanupsScope cleanups(*this); 1347 1348 for (BlockDecl::capture_const_iterator ci = blockDecl->capture_begin(), 1349 ce = blockDecl->capture_end(); ci != ce; ++ci) { 1350 const VarDecl *variable = ci->getVariable(); 1351 QualType type = variable->getType(); 1352 1353 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable); 1354 if (capture.isConstant()) continue; 1355 1356 BlockFieldFlags flags; 1357 const CXXDestructorDecl *dtor = 0; 1358 1359 bool isARCWeakCapture = false; 1360 1361 if (ci->isByRef()) { 1362 flags = BLOCK_FIELD_IS_BYREF; 1363 if (type.isObjCGCWeak()) 1364 flags |= BLOCK_FIELD_IS_WEAK; 1365 } else if (const CXXRecordDecl *record = type->getAsCXXRecordDecl()) { 1366 if (record->hasTrivialDestructor()) 1367 continue; 1368 dtor = record->getDestructor(); 1369 } else if (type->isObjCRetainableType()) { 1370 flags = BLOCK_FIELD_IS_OBJECT; 1371 if (type->isBlockPointerType()) 1372 flags = BLOCK_FIELD_IS_BLOCK; 1373 1374 // Special rules for ARC captures. 1375 if (getLangOpts().ObjCAutoRefCount) { 1376 Qualifiers qs = type.getQualifiers(); 1377 1378 // Don't generate special dispose logic for a captured object 1379 // unless it's __strong or __weak. 1380 if (!qs.hasStrongOrWeakObjCLifetime()) 1381 continue; 1382 1383 // Support __weak direct captures. 1384 if (qs.getObjCLifetime() == Qualifiers::OCL_Weak) 1385 isARCWeakCapture = true; 1386 } 1387 } else { 1388 continue; 1389 } 1390 1391 unsigned index = capture.getIndex(); 1392 llvm::Value *srcField = Builder.CreateStructGEP(src, index); 1393 1394 // If there's an explicit copy expression, we do that. 1395 if (dtor) { 1396 PushDestructorCleanup(dtor, srcField); 1397 1398 // If this is a __weak capture, emit the release directly. 1399 } else if (isARCWeakCapture) { 1400 EmitARCDestroyWeak(srcField); 1401 1402 // Otherwise we call _Block_object_dispose. It wouldn't be too 1403 // hard to just emit this as a cleanup if we wanted to make sure 1404 // that things were done in reverse. 1405 } else { 1406 llvm::Value *value = Builder.CreateLoad(srcField); 1407 value = Builder.CreateBitCast(value, VoidPtrTy); 1408 BuildBlockRelease(value, flags); 1409 } 1410 } 1411 1412 cleanups.ForceCleanup(); 1413 1414 FinishFunction(); 1415 1416 return llvm::ConstantExpr::getBitCast(Fn, VoidPtrTy); 1417 } 1418 1419 namespace { 1420 1421 /// Emits the copy/dispose helper functions for a __block object of id type. 1422 class ObjectByrefHelpers : public CodeGenModule::ByrefHelpers { 1423 BlockFieldFlags Flags; 1424 1425 public: 1426 ObjectByrefHelpers(CharUnits alignment, BlockFieldFlags flags) 1427 : ByrefHelpers(alignment), Flags(flags) {} 1428 1429 void emitCopy(CodeGenFunction &CGF, llvm::Value *destField, 1430 llvm::Value *srcField) { 1431 destField = CGF.Builder.CreateBitCast(destField, CGF.VoidPtrTy); 1432 1433 srcField = CGF.Builder.CreateBitCast(srcField, CGF.VoidPtrPtrTy); 1434 llvm::Value *srcValue = CGF.Builder.CreateLoad(srcField); 1435 1436 unsigned flags = (Flags | BLOCK_BYREF_CALLER).getBitMask(); 1437 1438 llvm::Value *flagsVal = llvm::ConstantInt::get(CGF.Int32Ty, flags); 1439 llvm::Value *fn = CGF.CGM.getBlockObjectAssign(); 1440 CGF.Builder.CreateCall3(fn, destField, srcValue, flagsVal); 1441 } 1442 1443 void emitDispose(CodeGenFunction &CGF, llvm::Value *field) { 1444 field = CGF.Builder.CreateBitCast(field, CGF.Int8PtrTy->getPointerTo(0)); 1445 llvm::Value *value = CGF.Builder.CreateLoad(field); 1446 1447 CGF.BuildBlockRelease(value, Flags | BLOCK_BYREF_CALLER); 1448 } 1449 1450 void profileImpl(llvm::FoldingSetNodeID &id) const { 1451 id.AddInteger(Flags.getBitMask()); 1452 } 1453 }; 1454 1455 /// Emits the copy/dispose helpers for an ARC __block __weak variable. 1456 class ARCWeakByrefHelpers : public CodeGenModule::ByrefHelpers { 1457 public: 1458 ARCWeakByrefHelpers(CharUnits alignment) : ByrefHelpers(alignment) {} 1459 1460 void emitCopy(CodeGenFunction &CGF, llvm::Value *destField, 1461 llvm::Value *srcField) { 1462 CGF.EmitARCMoveWeak(destField, srcField); 1463 } 1464 1465 void emitDispose(CodeGenFunction &CGF, llvm::Value *field) { 1466 CGF.EmitARCDestroyWeak(field); 1467 } 1468 1469 void profileImpl(llvm::FoldingSetNodeID &id) const { 1470 // 0 is distinguishable from all pointers and byref flags 1471 id.AddInteger(0); 1472 } 1473 }; 1474 1475 /// Emits the copy/dispose helpers for an ARC __block __strong variable 1476 /// that's not of block-pointer type. 1477 class ARCStrongByrefHelpers : public CodeGenModule::ByrefHelpers { 1478 public: 1479 ARCStrongByrefHelpers(CharUnits alignment) : ByrefHelpers(alignment) {} 1480 1481 void emitCopy(CodeGenFunction &CGF, llvm::Value *destField, 1482 llvm::Value *srcField) { 1483 // Do a "move" by copying the value and then zeroing out the old 1484 // variable. 1485 1486 llvm::LoadInst *value = CGF.Builder.CreateLoad(srcField); 1487 value->setAlignment(Alignment.getQuantity()); 1488 1489 llvm::Value *null = 1490 llvm::ConstantPointerNull::get(cast<llvm::PointerType>(value->getType())); 1491 1492 llvm::StoreInst *store = CGF.Builder.CreateStore(value, destField); 1493 store->setAlignment(Alignment.getQuantity()); 1494 1495 store = CGF.Builder.CreateStore(null, srcField); 1496 store->setAlignment(Alignment.getQuantity()); 1497 } 1498 1499 void emitDispose(CodeGenFunction &CGF, llvm::Value *field) { 1500 llvm::LoadInst *value = CGF.Builder.CreateLoad(field); 1501 value->setAlignment(Alignment.getQuantity()); 1502 1503 CGF.EmitARCRelease(value, /*precise*/ false); 1504 } 1505 1506 void profileImpl(llvm::FoldingSetNodeID &id) const { 1507 // 1 is distinguishable from all pointers and byref flags 1508 id.AddInteger(1); 1509 } 1510 }; 1511 1512 /// Emits the copy/dispose helpers for an ARC __block __strong 1513 /// variable that's of block-pointer type. 1514 class ARCStrongBlockByrefHelpers : public CodeGenModule::ByrefHelpers { 1515 public: 1516 ARCStrongBlockByrefHelpers(CharUnits alignment) : ByrefHelpers(alignment) {} 1517 1518 void emitCopy(CodeGenFunction &CGF, llvm::Value *destField, 1519 llvm::Value *srcField) { 1520 // Do the copy with objc_retainBlock; that's all that 1521 // _Block_object_assign would do anyway, and we'd have to pass the 1522 // right arguments to make sure it doesn't get no-op'ed. 1523 llvm::LoadInst *oldValue = CGF.Builder.CreateLoad(srcField); 1524 oldValue->setAlignment(Alignment.getQuantity()); 1525 1526 llvm::Value *copy = CGF.EmitARCRetainBlock(oldValue, /*mandatory*/ true); 1527 1528 llvm::StoreInst *store = CGF.Builder.CreateStore(copy, destField); 1529 store->setAlignment(Alignment.getQuantity()); 1530 } 1531 1532 void emitDispose(CodeGenFunction &CGF, llvm::Value *field) { 1533 llvm::LoadInst *value = CGF.Builder.CreateLoad(field); 1534 value->setAlignment(Alignment.getQuantity()); 1535 1536 CGF.EmitARCRelease(value, /*precise*/ false); 1537 } 1538 1539 void profileImpl(llvm::FoldingSetNodeID &id) const { 1540 // 2 is distinguishable from all pointers and byref flags 1541 id.AddInteger(2); 1542 } 1543 }; 1544 1545 /// Emits the copy/dispose helpers for a __block variable with a 1546 /// nontrivial copy constructor or destructor. 1547 class CXXByrefHelpers : public CodeGenModule::ByrefHelpers { 1548 QualType VarType; 1549 const Expr *CopyExpr; 1550 1551 public: 1552 CXXByrefHelpers(CharUnits alignment, QualType type, 1553 const Expr *copyExpr) 1554 : ByrefHelpers(alignment), VarType(type), CopyExpr(copyExpr) {} 1555 1556 bool needsCopy() const { return CopyExpr != 0; } 1557 void emitCopy(CodeGenFunction &CGF, llvm::Value *destField, 1558 llvm::Value *srcField) { 1559 if (!CopyExpr) return; 1560 CGF.EmitSynthesizedCXXCopyCtor(destField, srcField, CopyExpr); 1561 } 1562 1563 void emitDispose(CodeGenFunction &CGF, llvm::Value *field) { 1564 EHScopeStack::stable_iterator cleanupDepth = CGF.EHStack.stable_begin(); 1565 CGF.PushDestructorCleanup(VarType, field); 1566 CGF.PopCleanupBlocks(cleanupDepth); 1567 } 1568 1569 void profileImpl(llvm::FoldingSetNodeID &id) const { 1570 id.AddPointer(VarType.getCanonicalType().getAsOpaquePtr()); 1571 } 1572 }; 1573 } // end anonymous namespace 1574 1575 static llvm::Constant * 1576 generateByrefCopyHelper(CodeGenFunction &CGF, 1577 llvm::StructType &byrefType, 1578 CodeGenModule::ByrefHelpers &byrefInfo) { 1579 ASTContext &Context = CGF.getContext(); 1580 1581 QualType R = Context.VoidTy; 1582 1583 FunctionArgList args; 1584 ImplicitParamDecl dst(0, SourceLocation(), 0, Context.VoidPtrTy); 1585 args.push_back(&dst); 1586 1587 ImplicitParamDecl src(0, SourceLocation(), 0, Context.VoidPtrTy); 1588 args.push_back(&src); 1589 1590 const CGFunctionInfo &FI = 1591 CGF.CGM.getTypes().arrangeFunctionDeclaration(R, args, 1592 FunctionType::ExtInfo(), 1593 /*variadic*/ false); 1594 1595 CodeGenTypes &Types = CGF.CGM.getTypes(); 1596 llvm::FunctionType *LTy = Types.GetFunctionType(FI); 1597 1598 // FIXME: We'd like to put these into a mergable by content, with 1599 // internal linkage. 1600 llvm::Function *Fn = 1601 llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage, 1602 "__Block_byref_object_copy_", &CGF.CGM.getModule()); 1603 1604 IdentifierInfo *II 1605 = &Context.Idents.get("__Block_byref_object_copy_"); 1606 1607 FunctionDecl *FD = FunctionDecl::Create(Context, 1608 Context.getTranslationUnitDecl(), 1609 SourceLocation(), 1610 SourceLocation(), II, R, 0, 1611 SC_Static, 1612 SC_None, 1613 false, false); 1614 1615 CGF.StartFunction(FD, R, Fn, FI, args, SourceLocation()); 1616 1617 if (byrefInfo.needsCopy()) { 1618 llvm::Type *byrefPtrType = byrefType.getPointerTo(0); 1619 1620 // dst->x 1621 llvm::Value *destField = CGF.GetAddrOfLocalVar(&dst); 1622 destField = CGF.Builder.CreateLoad(destField); 1623 destField = CGF.Builder.CreateBitCast(destField, byrefPtrType); 1624 destField = CGF.Builder.CreateStructGEP(destField, 6, "x"); 1625 1626 // src->x 1627 llvm::Value *srcField = CGF.GetAddrOfLocalVar(&src); 1628 srcField = CGF.Builder.CreateLoad(srcField); 1629 srcField = CGF.Builder.CreateBitCast(srcField, byrefPtrType); 1630 srcField = CGF.Builder.CreateStructGEP(srcField, 6, "x"); 1631 1632 byrefInfo.emitCopy(CGF, destField, srcField); 1633 } 1634 1635 CGF.FinishFunction(); 1636 1637 return llvm::ConstantExpr::getBitCast(Fn, CGF.Int8PtrTy); 1638 } 1639 1640 /// Build the copy helper for a __block variable. 1641 static llvm::Constant *buildByrefCopyHelper(CodeGenModule &CGM, 1642 llvm::StructType &byrefType, 1643 CodeGenModule::ByrefHelpers &info) { 1644 CodeGenFunction CGF(CGM); 1645 return generateByrefCopyHelper(CGF, byrefType, info); 1646 } 1647 1648 /// Generate code for a __block variable's dispose helper. 1649 static llvm::Constant * 1650 generateByrefDisposeHelper(CodeGenFunction &CGF, 1651 llvm::StructType &byrefType, 1652 CodeGenModule::ByrefHelpers &byrefInfo) { 1653 ASTContext &Context = CGF.getContext(); 1654 QualType R = Context.VoidTy; 1655 1656 FunctionArgList args; 1657 ImplicitParamDecl src(0, SourceLocation(), 0, Context.VoidPtrTy); 1658 args.push_back(&src); 1659 1660 const CGFunctionInfo &FI = 1661 CGF.CGM.getTypes().arrangeFunctionDeclaration(R, args, 1662 FunctionType::ExtInfo(), 1663 /*variadic*/ false); 1664 1665 CodeGenTypes &Types = CGF.CGM.getTypes(); 1666 llvm::FunctionType *LTy = Types.GetFunctionType(FI); 1667 1668 // FIXME: We'd like to put these into a mergable by content, with 1669 // internal linkage. 1670 llvm::Function *Fn = 1671 llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage, 1672 "__Block_byref_object_dispose_", 1673 &CGF.CGM.getModule()); 1674 1675 IdentifierInfo *II 1676 = &Context.Idents.get("__Block_byref_object_dispose_"); 1677 1678 FunctionDecl *FD = FunctionDecl::Create(Context, 1679 Context.getTranslationUnitDecl(), 1680 SourceLocation(), 1681 SourceLocation(), II, R, 0, 1682 SC_Static, 1683 SC_None, 1684 false, false); 1685 CGF.StartFunction(FD, R, Fn, FI, args, SourceLocation()); 1686 1687 if (byrefInfo.needsDispose()) { 1688 llvm::Value *V = CGF.GetAddrOfLocalVar(&src); 1689 V = CGF.Builder.CreateLoad(V); 1690 V = CGF.Builder.CreateBitCast(V, byrefType.getPointerTo(0)); 1691 V = CGF.Builder.CreateStructGEP(V, 6, "x"); 1692 1693 byrefInfo.emitDispose(CGF, V); 1694 } 1695 1696 CGF.FinishFunction(); 1697 1698 return llvm::ConstantExpr::getBitCast(Fn, CGF.Int8PtrTy); 1699 } 1700 1701 /// Build the dispose helper for a __block variable. 1702 static llvm::Constant *buildByrefDisposeHelper(CodeGenModule &CGM, 1703 llvm::StructType &byrefType, 1704 CodeGenModule::ByrefHelpers &info) { 1705 CodeGenFunction CGF(CGM); 1706 return generateByrefDisposeHelper(CGF, byrefType, info); 1707 } 1708 1709 /// 1710 template <class T> static T *buildByrefHelpers(CodeGenModule &CGM, 1711 llvm::StructType &byrefTy, 1712 T &byrefInfo) { 1713 // Increase the field's alignment to be at least pointer alignment, 1714 // since the layout of the byref struct will guarantee at least that. 1715 byrefInfo.Alignment = std::max(byrefInfo.Alignment, 1716 CharUnits::fromQuantity(CGM.PointerAlignInBytes)); 1717 1718 llvm::FoldingSetNodeID id; 1719 byrefInfo.Profile(id); 1720 1721 void *insertPos; 1722 CodeGenModule::ByrefHelpers *node 1723 = CGM.ByrefHelpersCache.FindNodeOrInsertPos(id, insertPos); 1724 if (node) return static_cast<T*>(node); 1725 1726 byrefInfo.CopyHelper = buildByrefCopyHelper(CGM, byrefTy, byrefInfo); 1727 byrefInfo.DisposeHelper = buildByrefDisposeHelper(CGM, byrefTy, byrefInfo); 1728 1729 T *copy = new (CGM.getContext()) T(byrefInfo); 1730 CGM.ByrefHelpersCache.InsertNode(copy, insertPos); 1731 return copy; 1732 } 1733 1734 CodeGenModule::ByrefHelpers * 1735 CodeGenFunction::buildByrefHelpers(llvm::StructType &byrefType, 1736 const AutoVarEmission &emission) { 1737 const VarDecl &var = *emission.Variable; 1738 QualType type = var.getType(); 1739 1740 if (const CXXRecordDecl *record = type->getAsCXXRecordDecl()) { 1741 const Expr *copyExpr = CGM.getContext().getBlockVarCopyInits(&var); 1742 if (!copyExpr && record->hasTrivialDestructor()) return 0; 1743 1744 CXXByrefHelpers byrefInfo(emission.Alignment, type, copyExpr); 1745 return ::buildByrefHelpers(CGM, byrefType, byrefInfo); 1746 } 1747 1748 // Otherwise, if we don't have a retainable type, there's nothing to do. 1749 // that the runtime does extra copies. 1750 if (!type->isObjCRetainableType()) return 0; 1751 1752 Qualifiers qs = type.getQualifiers(); 1753 1754 // If we have lifetime, that dominates. 1755 if (Qualifiers::ObjCLifetime lifetime = qs.getObjCLifetime()) { 1756 assert(getLangOpts().ObjCAutoRefCount); 1757 1758 switch (lifetime) { 1759 case Qualifiers::OCL_None: llvm_unreachable("impossible"); 1760 1761 // These are just bits as far as the runtime is concerned. 1762 case Qualifiers::OCL_ExplicitNone: 1763 case Qualifiers::OCL_Autoreleasing: 1764 return 0; 1765 1766 // Tell the runtime that this is ARC __weak, called by the 1767 // byref routines. 1768 case Qualifiers::OCL_Weak: { 1769 ARCWeakByrefHelpers byrefInfo(emission.Alignment); 1770 return ::buildByrefHelpers(CGM, byrefType, byrefInfo); 1771 } 1772 1773 // ARC __strong __block variables need to be retained. 1774 case Qualifiers::OCL_Strong: 1775 // Block pointers need to be copied, and there's no direct 1776 // transfer possible. 1777 if (type->isBlockPointerType()) { 1778 ARCStrongBlockByrefHelpers byrefInfo(emission.Alignment); 1779 return ::buildByrefHelpers(CGM, byrefType, byrefInfo); 1780 1781 // Otherwise, we transfer ownership of the retain from the stack 1782 // to the heap. 1783 } else { 1784 ARCStrongByrefHelpers byrefInfo(emission.Alignment); 1785 return ::buildByrefHelpers(CGM, byrefType, byrefInfo); 1786 } 1787 } 1788 llvm_unreachable("fell out of lifetime switch!"); 1789 } 1790 1791 BlockFieldFlags flags; 1792 if (type->isBlockPointerType()) { 1793 flags |= BLOCK_FIELD_IS_BLOCK; 1794 } else if (CGM.getContext().isObjCNSObjectType(type) || 1795 type->isObjCObjectPointerType()) { 1796 flags |= BLOCK_FIELD_IS_OBJECT; 1797 } else { 1798 return 0; 1799 } 1800 1801 if (type.isObjCGCWeak()) 1802 flags |= BLOCK_FIELD_IS_WEAK; 1803 1804 ObjectByrefHelpers byrefInfo(emission.Alignment, flags); 1805 return ::buildByrefHelpers(CGM, byrefType, byrefInfo); 1806 } 1807 1808 unsigned CodeGenFunction::getByRefValueLLVMField(const ValueDecl *VD) const { 1809 assert(ByRefValueInfo.count(VD) && "Did not find value!"); 1810 1811 return ByRefValueInfo.find(VD)->second.second; 1812 } 1813 1814 llvm::Value *CodeGenFunction::BuildBlockByrefAddress(llvm::Value *BaseAddr, 1815 const VarDecl *V) { 1816 llvm::Value *Loc = Builder.CreateStructGEP(BaseAddr, 1, "forwarding"); 1817 Loc = Builder.CreateLoad(Loc); 1818 Loc = Builder.CreateStructGEP(Loc, getByRefValueLLVMField(V), 1819 V->getNameAsString()); 1820 return Loc; 1821 } 1822 1823 /// BuildByRefType - This routine changes a __block variable declared as T x 1824 /// into: 1825 /// 1826 /// struct { 1827 /// void *__isa; 1828 /// void *__forwarding; 1829 /// int32_t __flags; 1830 /// int32_t __size; 1831 /// void *__copy_helper; // only if needed 1832 /// void *__destroy_helper; // only if needed 1833 /// char padding[X]; // only if needed 1834 /// T x; 1835 /// } x 1836 /// 1837 llvm::Type *CodeGenFunction::BuildByRefType(const VarDecl *D) { 1838 std::pair<llvm::Type *, unsigned> &Info = ByRefValueInfo[D]; 1839 if (Info.first) 1840 return Info.first; 1841 1842 QualType Ty = D->getType(); 1843 1844 SmallVector<llvm::Type *, 8> types; 1845 1846 llvm::StructType *ByRefType = 1847 llvm::StructType::create(getLLVMContext(), 1848 "struct.__block_byref_" + D->getNameAsString()); 1849 1850 // void *__isa; 1851 types.push_back(Int8PtrTy); 1852 1853 // void *__forwarding; 1854 types.push_back(llvm::PointerType::getUnqual(ByRefType)); 1855 1856 // int32_t __flags; 1857 types.push_back(Int32Ty); 1858 1859 // int32_t __size; 1860 types.push_back(Int32Ty); 1861 1862 bool HasCopyAndDispose = 1863 (Ty->isObjCRetainableType()) || getContext().getBlockVarCopyInits(D); 1864 if (HasCopyAndDispose) { 1865 /// void *__copy_helper; 1866 types.push_back(Int8PtrTy); 1867 1868 /// void *__destroy_helper; 1869 types.push_back(Int8PtrTy); 1870 } 1871 1872 bool Packed = false; 1873 CharUnits Align = getContext().getDeclAlign(D); 1874 if (Align > getContext().toCharUnitsFromBits(Target.getPointerAlign(0))) { 1875 // We have to insert padding. 1876 1877 // The struct above has 2 32-bit integers. 1878 unsigned CurrentOffsetInBytes = 4 * 2; 1879 1880 // And either 2 or 4 pointers. 1881 CurrentOffsetInBytes += (HasCopyAndDispose ? 4 : 2) * 1882 CGM.getTargetData().getTypeAllocSize(Int8PtrTy); 1883 1884 // Align the offset. 1885 unsigned AlignedOffsetInBytes = 1886 llvm::RoundUpToAlignment(CurrentOffsetInBytes, Align.getQuantity()); 1887 1888 unsigned NumPaddingBytes = AlignedOffsetInBytes - CurrentOffsetInBytes; 1889 if (NumPaddingBytes > 0) { 1890 llvm::Type *Ty = Int8Ty; 1891 // FIXME: We need a sema error for alignment larger than the minimum of 1892 // the maximal stack alignment and the alignment of malloc on the system. 1893 if (NumPaddingBytes > 1) 1894 Ty = llvm::ArrayType::get(Ty, NumPaddingBytes); 1895 1896 types.push_back(Ty); 1897 1898 // We want a packed struct. 1899 Packed = true; 1900 } 1901 } 1902 1903 // T x; 1904 types.push_back(ConvertTypeForMem(Ty)); 1905 1906 ByRefType->setBody(types, Packed); 1907 1908 Info.first = ByRefType; 1909 1910 Info.second = types.size() - 1; 1911 1912 return Info.first; 1913 } 1914 1915 /// Initialize the structural components of a __block variable, i.e. 1916 /// everything but the actual object. 1917 void CodeGenFunction::emitByrefStructureInit(const AutoVarEmission &emission) { 1918 // Find the address of the local. 1919 llvm::Value *addr = emission.Address; 1920 1921 // That's an alloca of the byref structure type. 1922 llvm::StructType *byrefType = cast<llvm::StructType>( 1923 cast<llvm::PointerType>(addr->getType())->getElementType()); 1924 1925 // Build the byref helpers if necessary. This is null if we don't need any. 1926 CodeGenModule::ByrefHelpers *helpers = 1927 buildByrefHelpers(*byrefType, emission); 1928 1929 const VarDecl &D = *emission.Variable; 1930 QualType type = D.getType(); 1931 1932 llvm::Value *V; 1933 1934 // Initialize the 'isa', which is just 0 or 1. 1935 int isa = 0; 1936 if (type.isObjCGCWeak()) 1937 isa = 1; 1938 V = Builder.CreateIntToPtr(Builder.getInt32(isa), Int8PtrTy, "isa"); 1939 Builder.CreateStore(V, Builder.CreateStructGEP(addr, 0, "byref.isa")); 1940 1941 // Store the address of the variable into its own forwarding pointer. 1942 Builder.CreateStore(addr, 1943 Builder.CreateStructGEP(addr, 1, "byref.forwarding")); 1944 1945 // Blocks ABI: 1946 // c) the flags field is set to either 0 if no helper functions are 1947 // needed or BLOCK_HAS_COPY_DISPOSE if they are, 1948 BlockFlags flags; 1949 if (helpers) flags |= BLOCK_HAS_COPY_DISPOSE; 1950 Builder.CreateStore(llvm::ConstantInt::get(IntTy, flags.getBitMask()), 1951 Builder.CreateStructGEP(addr, 2, "byref.flags")); 1952 1953 CharUnits byrefSize = CGM.GetTargetTypeStoreSize(byrefType); 1954 V = llvm::ConstantInt::get(IntTy, byrefSize.getQuantity()); 1955 Builder.CreateStore(V, Builder.CreateStructGEP(addr, 3, "byref.size")); 1956 1957 if (helpers) { 1958 llvm::Value *copy_helper = Builder.CreateStructGEP(addr, 4); 1959 Builder.CreateStore(helpers->CopyHelper, copy_helper); 1960 1961 llvm::Value *destroy_helper = Builder.CreateStructGEP(addr, 5); 1962 Builder.CreateStore(helpers->DisposeHelper, destroy_helper); 1963 } 1964 } 1965 1966 void CodeGenFunction::BuildBlockRelease(llvm::Value *V, BlockFieldFlags flags) { 1967 llvm::Value *F = CGM.getBlockObjectDispose(); 1968 llvm::Value *N; 1969 V = Builder.CreateBitCast(V, Int8PtrTy); 1970 N = llvm::ConstantInt::get(Int32Ty, flags.getBitMask()); 1971 Builder.CreateCall2(F, V, N); 1972 } 1973 1974 namespace { 1975 struct CallBlockRelease : EHScopeStack::Cleanup { 1976 llvm::Value *Addr; 1977 CallBlockRelease(llvm::Value *Addr) : Addr(Addr) {} 1978 1979 void Emit(CodeGenFunction &CGF, Flags flags) { 1980 // Should we be passing FIELD_IS_WEAK here? 1981 CGF.BuildBlockRelease(Addr, BLOCK_FIELD_IS_BYREF); 1982 } 1983 }; 1984 } 1985 1986 /// Enter a cleanup to destroy a __block variable. Note that this 1987 /// cleanup should be a no-op if the variable hasn't left the stack 1988 /// yet; if a cleanup is required for the variable itself, that needs 1989 /// to be done externally. 1990 void CodeGenFunction::enterByrefCleanup(const AutoVarEmission &emission) { 1991 // We don't enter this cleanup if we're in pure-GC mode. 1992 if (CGM.getLangOpts().getGC() == LangOptions::GCOnly) 1993 return; 1994 1995 EHStack.pushCleanup<CallBlockRelease>(NormalAndEHCleanup, emission.Address); 1996 } 1997 1998 /// Adjust the declaration of something from the blocks API. 1999 static void configureBlocksRuntimeObject(CodeGenModule &CGM, 2000 llvm::Constant *C) { 2001 if (!CGM.getLangOpts().BlocksRuntimeOptional) return; 2002 2003 llvm::GlobalValue *GV = cast<llvm::GlobalValue>(C->stripPointerCasts()); 2004 if (GV->isDeclaration() && 2005 GV->getLinkage() == llvm::GlobalValue::ExternalLinkage) 2006 GV->setLinkage(llvm::GlobalValue::ExternalWeakLinkage); 2007 } 2008 2009 llvm::Constant *CodeGenModule::getBlockObjectDispose() { 2010 if (BlockObjectDispose) 2011 return BlockObjectDispose; 2012 2013 llvm::Type *args[] = { Int8PtrTy, Int32Ty }; 2014 llvm::FunctionType *fty 2015 = llvm::FunctionType::get(VoidTy, args, false); 2016 BlockObjectDispose = CreateRuntimeFunction(fty, "_Block_object_dispose"); 2017 configureBlocksRuntimeObject(*this, BlockObjectDispose); 2018 return BlockObjectDispose; 2019 } 2020 2021 llvm::Constant *CodeGenModule::getBlockObjectAssign() { 2022 if (BlockObjectAssign) 2023 return BlockObjectAssign; 2024 2025 llvm::Type *args[] = { Int8PtrTy, Int8PtrTy, Int32Ty }; 2026 llvm::FunctionType *fty 2027 = llvm::FunctionType::get(VoidTy, args, false); 2028 BlockObjectAssign = CreateRuntimeFunction(fty, "_Block_object_assign"); 2029 configureBlocksRuntimeObject(*this, BlockObjectAssign); 2030 return BlockObjectAssign; 2031 } 2032 2033 llvm::Constant *CodeGenModule::getNSConcreteGlobalBlock() { 2034 if (NSConcreteGlobalBlock) 2035 return NSConcreteGlobalBlock; 2036 2037 NSConcreteGlobalBlock = GetOrCreateLLVMGlobal("_NSConcreteGlobalBlock", 2038 Int8PtrTy->getPointerTo(), 0); 2039 configureBlocksRuntimeObject(*this, NSConcreteGlobalBlock); 2040 return NSConcreteGlobalBlock; 2041 } 2042 2043 llvm::Constant *CodeGenModule::getNSConcreteStackBlock() { 2044 if (NSConcreteStackBlock) 2045 return NSConcreteStackBlock; 2046 2047 NSConcreteStackBlock = GetOrCreateLLVMGlobal("_NSConcreteStackBlock", 2048 Int8PtrTy->getPointerTo(), 0); 2049 configureBlocksRuntimeObject(*this, NSConcreteStackBlock); 2050 return NSConcreteStackBlock; 2051 } 2052