1 //===--- CGBlocks.cpp - Emit LLVM Code for declarations -------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This contains code to emit blocks.
12 //===----------------------------------------------------------------------===//
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"
27 using namespace clang;
28 using namespace CodeGen;
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) {
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);
42 // Anchor the vtable to this translation unit.
43 CodeGenModule::ByrefHelpers::~ByrefHelpers() {}
45 /// Build the given block as a global block.
46 static llvm::Constant *buildGlobalBlock(CodeGenModule &CGM,
47 const CGBlockInfo &blockInfo,
48 llvm::Constant *blockFn);
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);
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);
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.
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.
76 static llvm::Constant *buildBlockDescriptor(CodeGenModule &CGM,
77 const CGBlockInfo &blockInfo) {
78 ASTContext &C = CGM.getContext();
80 llvm::Type *ulong = CGM.getTypes().ConvertType(C.UnsignedLongTy);
81 llvm::Type *i8p = NULL;
82 if (CGM.getLangOpts().OpenCL)
84 llvm::Type::getInt8PtrTy(
85 CGM.getLLVMContext(), C.getTargetAddressSpace(LangAS::opencl_constant));
87 i8p = CGM.getTypes().ConvertType(C.VoidPtrTy);
89 SmallVector<llvm::Constant*, 6> elements;
92 elements.push_back(llvm::ConstantInt::get(ulong, 0));
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
98 elements.push_back(llvm::ConstantInt::get(ulong,
99 blockInfo.BlockSize.getQuantity()));
101 // Optional copy/dispose helpers.
102 if (blockInfo.NeedsCopyDispose) {
103 // copy_func_helper_decl
104 elements.push_back(buildCopyHelper(CGM, blockInfo));
107 elements.push_back(buildDisposeHelper(CGM, blockInfo));
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));
117 if (C.getLangOpts().ObjC1) {
118 if (CGM.getLangOpts().getGC() != LangOptions::NonGC)
119 elements.push_back(CGM.getObjCRuntime().BuildGCBlockLayout(CGM, blockInfo));
121 elements.push_back(CGM.getObjCRuntime().BuildRCBlockLayout(CGM, blockInfo));
124 elements.push_back(llvm::Constant::getNullValue(i8p));
126 llvm::Constant *init = llvm::ConstantStruct::getAnon(elements);
128 llvm::GlobalVariable *global =
129 new llvm::GlobalVariable(CGM.getModule(), init->getType(), true,
130 llvm::GlobalValue::InternalLinkage,
131 init, "__block_descriptor_tmp");
133 return llvm::ConstantExpr::getBitCast(global, CGM.getBlockDescriptorType());
137 Purely notional variadic template describing the layout of a block.
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[];
145 /// In theory, we could start one off malloc'ed by setting
146 /// BLOCK_NEEDS_FREE, giving it a refcount of 1, and using
148 /// extern void *_NSConcreteMallocBlock[];
149 struct objc_class *isa;
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
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.
172 /// Reserved; should be zero-initialized.
175 /// Function pointer generated from block literal.
176 _ResultType (*invoke)(Block_literal *, _ParamTypes...);
178 /// Block description metadata generated from block literal.
179 struct Block_descriptor *block_descriptor;
181 /// Captured values follow.
182 _CapturesTypes captures...;
186 /// The number of fields in a block header.
187 const unsigned BlockHeaderSize = 5;
190 /// A chunk of data that we actually have to capture in the block.
191 struct BlockLayoutChunk {
194 Qualifiers::ObjCLifetime Lifetime;
195 const BlockDecl::Capture *Capture; // null for 'this'
198 BlockLayoutChunk(CharUnits align, CharUnits size,
199 Qualifiers::ObjCLifetime lifetime,
200 const BlockDecl::Capture *capture,
202 : Alignment(align), Size(size), Lifetime(lifetime),
203 Capture(capture), Type(type) {}
205 /// Tell the block info that this chunk has the given field index.
206 void setIndex(CGBlockInfo &info, unsigned index) {
208 info.CXXThisIndex = index;
210 info.Captures[Capture->getVariable()]
211 = CGBlockInfo::Capture::makeIndex(index);
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;
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);
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);
241 RightValue = right.Alignment;
243 return LeftValue > RightValue;
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>();
252 // Only records can be unsafe.
253 if (!recordType) return true;
255 const auto *record = cast<CXXRecordDecl>(recordType->getDecl());
257 // Maintain semantics for classes with non-trivial dtors or copy ctors.
258 if (!record->hasTrivialDestructor()) return false;
259 if (record->hasNonTrivialCopyConstructor()) return false;
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();
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();
277 // We can only do this if the variable is const.
278 if (!type.isConstQualified()) return nullptr;
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))
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
291 const Expr *init = var->getInit();
292 if (!init) return nullptr;
294 return CGM.EmitConstantInit(*var, CGF);
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));
303 static void initializeForBlockHeader(CodeGenModule &CGM, CGBlockInfo &info,
304 SmallVectorImpl<llvm::Type*> &elementTypes) {
305 ASTContext &C = CGM.getContext();
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);
312 // Are there crazy embedded platforms where this isn't true?
313 assert(intSize <= ptrSize && "layout assumptions horribly violated");
315 CharUnits headerSize = ptrSize;
316 if (2 * intSize < ptrAlign) headerSize += ptrSize;
317 else headerSize += 2 * intSize;
318 headerSize += 2 * ptrSize;
320 info.BlockAlign = ptrAlign;
321 info.BlockSize = headerSize;
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());
332 assert(elementTypes.size() == BlockHeaderSize);
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,
339 ASTContext &C = CGM.getContext();
340 const BlockDecl *block = info.getBlockDecl();
342 SmallVector<llvm::Type*, 8> elementTypes;
343 initializeForBlockHeader(CGM, info, elementTypes);
345 if (!block->hasCaptures()) {
347 llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true);
348 info.CanBeGlobal = true;
351 else if (C.getLangOpts().ObjC1 &&
352 CGM.getLangOpts().getGC() == LangOptions::NonGC)
353 info.HasCapturedVariableLayout = true;
355 // Collect the layout chunks.
356 SmallVector<BlockLayoutChunk, 16> layout;
357 layout.reserve(block->capturesCXXThis() +
358 (block->capture_end() - block->capture_begin()));
360 CharUnits maxFieldAlign;
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);
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);
373 layout.push_back(BlockLayoutChunk(tinfo.second, tinfo.first,
374 Qualifiers::OCL_None,
378 // Next, all the block captures.
379 for (const auto &CI : block->captures()) {
380 const VarDecl *variable = CI.getVariable();
383 // We have to copy/dispose of the __block reference.
384 info.NeedsCopyDispose = true;
386 // Just use void* instead of a pointer to the byref type.
387 QualType byRefPtrTy = C.VoidPtrTy;
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);
394 layout.push_back(BlockLayoutChunk(tinfo.second, tinfo.first,
395 Qualifiers::OCL_None, &CI, llvmType));
399 // Otherwise, build a layout chunk with the size and alignment of
401 if (llvm::Constant *constant = tryCaptureAsConstant(CGM, CGF, variable)) {
402 info.Captures[variable] = CGBlockInfo::Capture::makeConstant(constant);
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();
412 case Qualifiers::OCL_None: llvm_unreachable("impossible");
413 case Qualifiers::OCL_ExplicitNone:
414 case Qualifiers::OCL_Autoreleasing:
417 case Qualifiers::OCL_Strong:
418 case Qualifiers::OCL_Weak:
419 info.NeedsCopyDispose = true;
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;
428 // So do types that require non-trivial copy construction.
429 } else if (CI.hasCopyExpr()) {
430 info.NeedsCopyDispose = true;
431 info.HasCXXObject = true;
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;
444 QualType VT = variable->getType();
445 CharUnits size = C.getTypeSizeInChars(VT);
446 CharUnits align = C.getDeclAlign(variable);
448 maxFieldAlign = std::max(maxFieldAlign, align);
450 llvm::Type *llvmType =
451 CGM.getTypes().ConvertTypeForMem(VT);
453 layout.push_back(BlockLayoutChunk(align, size, lifetime, &CI, llvmType));
456 // If that was everything, we're done here.
457 if (layout.empty()) {
459 llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true);
460 info.CanBeGlobal = true;
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());
469 // Needed for blocks layout info.
470 info.BlockHeaderForcedGapOffset = info.BlockSize;
471 info.BlockHeaderForcedGapSize = CharUnits::Zero();
473 CharUnits &blockSize = info.BlockSize;
474 info.BlockAlign = std::max(maxFieldAlign, info.BlockAlign);
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);
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
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();
495 // Look for something that the header end is already
496 // satisfactorily aligned for.
497 for (; li != le && endAlign < li->Alignment; ++li)
500 // If we found something that's naturally aligned for the end of
501 // the header, keep adding things...
503 SmallVectorImpl<BlockLayoutChunk>::iterator first = li;
504 for (; li != le; ++li) {
505 assert(endAlign >= li->Alignment);
507 li->setIndex(info, elementTypes.size());
508 elementTypes.push_back(li->Type);
509 blockSize += li->Size;
510 endAlign = getLowBit(blockSize);
512 // ...until we get to the alignment of the maximum field.
513 if (endAlign >= maxFieldAlign) {
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;
522 // Don't re-append everything we just appended.
523 layout.erase(first, li);
527 assert(endAlign == getLowBit(blockSize));
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;
535 elementTypes.push_back(llvm::ArrayType::get(CGM.Int8Ty,
536 padding.getQuantity()));
537 blockSize = newBlockSize;
538 endAlign = getLowBit(blockSize); // might be > maxFieldAlign
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 assert(endAlign >= li->Alignment);
549 li->setIndex(info, elementTypes.size());
550 elementTypes.push_back(li->Type);
551 blockSize += li->Size;
552 endAlign = getLowBit(blockSize);
556 llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true);
559 /// Enter the scope of a block. This should be run at the entrance to
560 /// a full-expression so that the block's cleanups are pushed at the
561 /// right place in the stack.
562 static void enterBlockScope(CodeGenFunction &CGF, BlockDecl *block) {
563 assert(CGF.HaveInsertPoint());
565 // Allocate the block info and place it at the head of the list.
566 CGBlockInfo &blockInfo =
567 *new CGBlockInfo(block, CGF.CurFn->getName());
568 blockInfo.NextBlockInfo = CGF.FirstBlockInfo;
569 CGF.FirstBlockInfo = &blockInfo;
571 // Compute information about the layout, etc., of this block,
572 // pushing cleanups as necessary.
573 computeBlockInfo(CGF.CGM, &CGF, blockInfo);
575 // Nothing else to do if it can be global.
576 if (blockInfo.CanBeGlobal) return;
578 // Make the allocation for the block.
580 CGF.CreateTempAlloca(blockInfo.StructureType, "block");
581 blockInfo.Address->setAlignment(blockInfo.BlockAlign.getQuantity());
583 // If there are cleanups to emit, enter them (but inactive).
584 if (!blockInfo.NeedsCopyDispose) return;
586 // Walk through the captures (in order) and find the ones not
587 // captured by constant.
588 for (const auto &CI : block->captures()) {
589 // Ignore __block captures; there's nothing special in the
590 // on-stack block that we need to do for them.
591 if (CI.isByRef()) continue;
593 // Ignore variables that are constant-captured.
594 const VarDecl *variable = CI.getVariable();
595 CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
596 if (capture.isConstant()) continue;
598 // Ignore objects that aren't destructed.
599 QualType::DestructionKind dtorKind =
600 variable->getType().isDestructedType();
601 if (dtorKind == QualType::DK_none) continue;
603 CodeGenFunction::Destroyer *destroyer;
605 // Block captures count as local values and have imprecise semantics.
606 // They also can't be arrays, so need to worry about that.
607 if (dtorKind == QualType::DK_objc_strong_lifetime) {
608 destroyer = CodeGenFunction::destroyARCStrongImprecise;
610 destroyer = CGF.getDestroyer(dtorKind);
613 // GEP down to the address.
614 llvm::Value *addr = CGF.Builder.CreateStructGEP(blockInfo.Address,
617 // We can use that GEP as the dominating IP.
618 if (!blockInfo.DominatingIP)
619 blockInfo.DominatingIP = cast<llvm::Instruction>(addr);
621 CleanupKind cleanupKind = InactiveNormalCleanup;
622 bool useArrayEHCleanup = CGF.needsEHCleanup(dtorKind);
623 if (useArrayEHCleanup)
624 cleanupKind = InactiveNormalAndEHCleanup;
626 CGF.pushDestroy(cleanupKind, addr, variable->getType(),
627 destroyer, useArrayEHCleanup);
629 // Remember where that cleanup was.
630 capture.setCleanup(CGF.EHStack.stable_begin());
634 /// Enter a full-expression with a non-trivial number of objects to
635 /// clean up. This is in this file because, at the moment, the only
636 /// kind of cleanup object is a BlockDecl*.
637 void CodeGenFunction::enterNonTrivialFullExpression(const ExprWithCleanups *E) {
638 assert(E->getNumObjects() != 0);
639 ArrayRef<ExprWithCleanups::CleanupObject> cleanups = E->getObjects();
640 for (ArrayRef<ExprWithCleanups::CleanupObject>::iterator
641 i = cleanups.begin(), e = cleanups.end(); i != e; ++i) {
642 enterBlockScope(*this, *i);
646 /// Find the layout for the given block in a linked list and remove it.
647 static CGBlockInfo *findAndRemoveBlockInfo(CGBlockInfo **head,
648 const BlockDecl *block) {
650 assert(head && *head);
651 CGBlockInfo *cur = *head;
653 // If this is the block we're looking for, splice it out of the list.
654 if (cur->getBlockDecl() == block) {
655 *head = cur->NextBlockInfo;
659 head = &cur->NextBlockInfo;
663 /// Destroy a chain of block layouts.
664 void CodeGenFunction::destroyBlockInfos(CGBlockInfo *head) {
665 assert(head && "destroying an empty chain");
667 CGBlockInfo *cur = head;
668 head = cur->NextBlockInfo;
670 } while (head != nullptr);
673 /// Emit a block literal expression in the current function.
674 llvm::Value *CodeGenFunction::EmitBlockLiteral(const BlockExpr *blockExpr) {
675 // If the block has no captures, we won't have a pre-computed
677 if (!blockExpr->getBlockDecl()->hasCaptures()) {
678 CGBlockInfo blockInfo(blockExpr->getBlockDecl(), CurFn->getName());
679 computeBlockInfo(CGM, this, blockInfo);
680 blockInfo.BlockExpression = blockExpr;
681 return EmitBlockLiteral(blockInfo);
684 // Find the block info for this block and take ownership of it.
685 std::unique_ptr<CGBlockInfo> blockInfo;
686 blockInfo.reset(findAndRemoveBlockInfo(&FirstBlockInfo,
687 blockExpr->getBlockDecl()));
689 blockInfo->BlockExpression = blockExpr;
690 return EmitBlockLiteral(*blockInfo);
693 llvm::Value *CodeGenFunction::EmitBlockLiteral(const CGBlockInfo &blockInfo) {
694 // Using the computed layout, generate the actual block function.
695 bool isLambdaConv = blockInfo.getBlockDecl()->isConversionFromLambda();
696 llvm::Constant *blockFn
697 = CodeGenFunction(CGM, true).GenerateBlockFunction(CurGD, blockInfo,
700 blockFn = llvm::ConstantExpr::getBitCast(blockFn, VoidPtrTy);
702 // If there is nothing to capture, we can emit this as a global block.
703 if (blockInfo.CanBeGlobal)
704 return buildGlobalBlock(CGM, blockInfo, blockFn);
706 // Otherwise, we have to emit this as a local block.
708 llvm::Constant *isa = CGM.getNSConcreteStackBlock();
709 isa = llvm::ConstantExpr::getBitCast(isa, VoidPtrTy);
711 // Build the block descriptor.
712 llvm::Constant *descriptor = buildBlockDescriptor(CGM, blockInfo);
714 llvm::AllocaInst *blockAddr = blockInfo.Address;
715 assert(blockAddr && "block has no address!");
717 // Compute the initial on-stack block flags.
718 BlockFlags flags = BLOCK_HAS_SIGNATURE;
719 if (blockInfo.HasCapturedVariableLayout) flags |= BLOCK_HAS_EXTENDED_LAYOUT;
720 if (blockInfo.NeedsCopyDispose) flags |= BLOCK_HAS_COPY_DISPOSE;
721 if (blockInfo.HasCXXObject) flags |= BLOCK_HAS_CXX_OBJ;
722 if (blockInfo.UsesStret) flags |= BLOCK_USE_STRET;
724 // Initialize the block literal.
725 Builder.CreateStore(isa, Builder.CreateStructGEP(blockAddr, 0, "block.isa"));
726 Builder.CreateStore(llvm::ConstantInt::get(IntTy, flags.getBitMask()),
727 Builder.CreateStructGEP(blockAddr, 1, "block.flags"));
728 Builder.CreateStore(llvm::ConstantInt::get(IntTy, 0),
729 Builder.CreateStructGEP(blockAddr, 2, "block.reserved"));
730 Builder.CreateStore(blockFn, Builder.CreateStructGEP(blockAddr, 3,
732 Builder.CreateStore(descriptor, Builder.CreateStructGEP(blockAddr, 4,
733 "block.descriptor"));
735 // Finally, capture all the values into the block.
736 const BlockDecl *blockDecl = blockInfo.getBlockDecl();
739 if (blockDecl->capturesCXXThis()) {
740 llvm::Value *addr = Builder.CreateStructGEP(blockAddr,
741 blockInfo.CXXThisIndex,
742 "block.captured-this.addr");
743 Builder.CreateStore(LoadCXXThis(), addr);
746 // Next, captured variables.
747 for (const auto &CI : blockDecl->captures()) {
748 const VarDecl *variable = CI.getVariable();
749 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
751 // Ignore constant captures.
752 if (capture.isConstant()) continue;
754 QualType type = variable->getType();
755 CharUnits align = getContext().getDeclAlign(variable);
757 // This will be a [[type]]*, except that a byref entry will just be
759 llvm::Value *blockField =
760 Builder.CreateStructGEP(blockAddr, capture.getIndex(),
763 // Compute the address of the thing we're going to move into the
766 if (BlockInfo && CI.isNested()) {
767 // We need to use the capture from the enclosing block.
768 const CGBlockInfo::Capture &enclosingCapture =
769 BlockInfo->getCapture(variable);
771 // This is a [[type]]*, except that a byref entry wil just be an i8**.
772 src = Builder.CreateStructGEP(LoadBlockStruct(),
773 enclosingCapture.getIndex(),
774 "block.capture.addr");
775 } else if (blockDecl->isConversionFromLambda()) {
776 // The lambda capture in a lambda's conversion-to-block-pointer is
777 // special; we'll simply emit it directly.
780 // Just look it up in the locals map, which will give us back a
781 // [[type]]*. If that doesn't work, do the more elaborate DRE
783 src = LocalDeclMap.lookup(variable);
785 DeclRefExpr declRef(const_cast<VarDecl *>(variable),
786 /*refersToEnclosing*/ CI.isNested(), type,
787 VK_LValue, SourceLocation());
788 src = EmitDeclRefLValue(&declRef).getAddress();
792 // For byrefs, we just write the pointer to the byref struct into
793 // the block field. There's no need to chase the forwarding
794 // pointer at this point, since we're building something that will
795 // live a shorter life than the stack byref anyway.
797 // Get a void* that points to the byref struct.
799 src = Builder.CreateAlignedLoad(src, align.getQuantity(),
802 src = Builder.CreateBitCast(src, VoidPtrTy);
804 // Write that void* into the capture field.
805 Builder.CreateAlignedStore(src, blockField, align.getQuantity());
807 // If we have a copy constructor, evaluate that into the block field.
808 } else if (const Expr *copyExpr = CI.getCopyExpr()) {
809 if (blockDecl->isConversionFromLambda()) {
810 // If we have a lambda conversion, emit the expression
811 // directly into the block instead.
813 AggValueSlot::forAddr(blockField, align, Qualifiers(),
814 AggValueSlot::IsDestructed,
815 AggValueSlot::DoesNotNeedGCBarriers,
816 AggValueSlot::IsNotAliased);
817 EmitAggExpr(copyExpr, Slot);
819 EmitSynthesizedCXXCopyCtor(blockField, src, copyExpr);
822 // If it's a reference variable, copy the reference into the block field.
823 } else if (type->isReferenceType()) {
825 Builder.CreateAlignedLoad(src, align.getQuantity(), "ref.val");
826 Builder.CreateAlignedStore(ref, blockField, align.getQuantity());
828 // If this is an ARC __strong block-pointer variable, don't do a
831 // TODO: this can be generalized into the normal initialization logic:
832 // we should never need to do a block-copy when initializing a local
833 // variable, because the local variable's lifetime should be strictly
834 // contained within the stack block's.
835 } else if (type.getObjCLifetime() == Qualifiers::OCL_Strong &&
836 type->isBlockPointerType()) {
837 // Load the block and do a simple retain.
838 LValue srcLV = MakeAddrLValue(src, type, align);
839 llvm::Value *value = EmitLoadOfScalar(srcLV, SourceLocation());
840 value = EmitARCRetainNonBlock(value);
842 // Do a primitive store to the block field.
843 LValue destLV = MakeAddrLValue(blockField, type, align);
844 EmitStoreOfScalar(value, destLV, /*init*/ true);
846 // Otherwise, fake up a POD copy into the block field.
848 // Fake up a new variable so that EmitScalarInit doesn't think
849 // we're referring to the variable in its own initializer.
850 ImplicitParamDecl blockFieldPseudoVar(getContext(), /*DC*/ nullptr,
851 SourceLocation(), /*name*/ nullptr,
854 // We use one of these or the other depending on whether the
855 // reference is nested.
856 DeclRefExpr declRef(const_cast<VarDecl*>(variable),
857 /*refersToEnclosing*/ CI.isNested(), type,
858 VK_LValue, SourceLocation());
860 ImplicitCastExpr l2r(ImplicitCastExpr::OnStack, type, CK_LValueToRValue,
861 &declRef, VK_RValue);
862 EmitExprAsInit(&l2r, &blockFieldPseudoVar,
863 MakeAddrLValue(blockField, type, align),
864 /*captured by init*/ false);
867 // Activate the cleanup if layout pushed one.
869 EHScopeStack::stable_iterator cleanup = capture.getCleanup();
870 if (cleanup.isValid())
871 ActivateCleanupBlock(cleanup, blockInfo.DominatingIP);
875 // Cast to the converted block-pointer type, which happens (somewhat
876 // unfortunately) to be a pointer to function type.
877 llvm::Value *result =
878 Builder.CreateBitCast(blockAddr,
879 ConvertType(blockInfo.getBlockExpr()->getType()));
885 llvm::Type *CodeGenModule::getBlockDescriptorType() {
886 if (BlockDescriptorType)
887 return BlockDescriptorType;
889 llvm::Type *UnsignedLongTy =
890 getTypes().ConvertType(getContext().UnsignedLongTy);
892 // struct __block_descriptor {
893 // unsigned long reserved;
894 // unsigned long block_size;
896 // // later, the following will be added
899 // void (*copyHelper)();
900 // void (*copyHelper)();
901 // } helpers; // !!! optional
903 // const char *signature; // the block signature
904 // const char *layout; // reserved
906 BlockDescriptorType =
907 llvm::StructType::create("struct.__block_descriptor",
908 UnsignedLongTy, UnsignedLongTy, NULL);
910 // Now form a pointer to that.
911 BlockDescriptorType = llvm::PointerType::getUnqual(BlockDescriptorType);
912 return BlockDescriptorType;
915 llvm::Type *CodeGenModule::getGenericBlockLiteralType() {
916 if (GenericBlockLiteralType)
917 return GenericBlockLiteralType;
919 llvm::Type *BlockDescPtrTy = getBlockDescriptorType();
921 // struct __block_literal_generic {
925 // void (*__invoke)(void *);
926 // struct __block_descriptor *__descriptor;
928 GenericBlockLiteralType =
929 llvm::StructType::create("struct.__block_literal_generic",
930 VoidPtrTy, IntTy, IntTy, VoidPtrTy,
931 BlockDescPtrTy, NULL);
933 return GenericBlockLiteralType;
937 RValue CodeGenFunction::EmitBlockCallExpr(const CallExpr *E,
938 ReturnValueSlot ReturnValue) {
939 const BlockPointerType *BPT =
940 E->getCallee()->getType()->getAs<BlockPointerType>();
942 llvm::Value *Callee = EmitScalarExpr(E->getCallee());
944 // Get a pointer to the generic block literal.
945 llvm::Type *BlockLiteralTy =
946 llvm::PointerType::getUnqual(CGM.getGenericBlockLiteralType());
948 // Bitcast the callee to a block literal.
949 llvm::Value *BlockLiteral =
950 Builder.CreateBitCast(Callee, BlockLiteralTy, "block.literal");
952 // Get the function pointer from the literal.
953 llvm::Value *FuncPtr = Builder.CreateStructGEP(BlockLiteral, 3);
955 BlockLiteral = Builder.CreateBitCast(BlockLiteral, VoidPtrTy);
957 // Add the block literal.
959 Args.add(RValue::get(BlockLiteral), getContext().VoidPtrTy);
961 QualType FnType = BPT->getPointeeType();
963 // And the rest of the arguments.
964 EmitCallArgs(Args, FnType->getAs<FunctionProtoType>(),
965 E->arg_begin(), E->arg_end());
967 // Load the function.
968 llvm::Value *Func = Builder.CreateLoad(FuncPtr);
970 const FunctionType *FuncTy = FnType->castAs<FunctionType>();
971 const CGFunctionInfo &FnInfo =
972 CGM.getTypes().arrangeBlockFunctionCall(Args, FuncTy);
974 // Cast the function pointer to the right type.
975 llvm::Type *BlockFTy = CGM.getTypes().GetFunctionType(FnInfo);
977 llvm::Type *BlockFTyPtr = llvm::PointerType::getUnqual(BlockFTy);
978 Func = Builder.CreateBitCast(Func, BlockFTyPtr);
980 // And call the block.
981 return EmitCall(FnInfo, Func, ReturnValue, Args);
984 llvm::Value *CodeGenFunction::GetAddrOfBlockDecl(const VarDecl *variable,
986 assert(BlockInfo && "evaluating block ref without block information?");
987 const CGBlockInfo::Capture &capture = BlockInfo->getCapture(variable);
989 // Handle constant captures.
990 if (capture.isConstant()) return LocalDeclMap[variable];
993 Builder.CreateStructGEP(LoadBlockStruct(), capture.getIndex(),
994 "block.capture.addr");
997 // addr should be a void** right now. Load, then cast the result
1000 addr = Builder.CreateLoad(addr);
1001 llvm::PointerType *byrefPointerType
1002 = llvm::PointerType::get(BuildByRefType(variable), 0);
1003 addr = Builder.CreateBitCast(addr, byrefPointerType,
1006 // Follow the forwarding pointer.
1007 addr = Builder.CreateStructGEP(addr, 1, "byref.forwarding");
1008 addr = Builder.CreateLoad(addr, "byref.addr.forwarded");
1010 // Cast back to byref* and GEP over to the actual object.
1011 addr = Builder.CreateBitCast(addr, byrefPointerType);
1012 addr = Builder.CreateStructGEP(addr, getByRefValueLLVMField(variable),
1013 variable->getNameAsString());
1016 if (variable->getType()->isReferenceType())
1017 addr = Builder.CreateLoad(addr, "ref.tmp");
1023 CodeGenModule::GetAddrOfGlobalBlock(const BlockExpr *blockExpr,
1025 CGBlockInfo blockInfo(blockExpr->getBlockDecl(), name);
1026 blockInfo.BlockExpression = blockExpr;
1028 // Compute information about the layout, etc., of this block.
1029 computeBlockInfo(*this, nullptr, blockInfo);
1031 // Using that metadata, generate the actual block function.
1032 llvm::Constant *blockFn;
1034 llvm::DenseMap<const Decl*, llvm::Value*> LocalDeclMap;
1035 blockFn = CodeGenFunction(*this).GenerateBlockFunction(GlobalDecl(),
1040 blockFn = llvm::ConstantExpr::getBitCast(blockFn, VoidPtrTy);
1042 return buildGlobalBlock(*this, blockInfo, blockFn);
1045 static llvm::Constant *buildGlobalBlock(CodeGenModule &CGM,
1046 const CGBlockInfo &blockInfo,
1047 llvm::Constant *blockFn) {
1048 assert(blockInfo.CanBeGlobal);
1050 // Generate the constants for the block literal initializer.
1051 llvm::Constant *fields[BlockHeaderSize];
1054 fields[0] = CGM.getNSConcreteGlobalBlock();
1057 BlockFlags flags = BLOCK_IS_GLOBAL | BLOCK_HAS_SIGNATURE;
1058 if (blockInfo.UsesStret) flags |= BLOCK_USE_STRET;
1060 fields[1] = llvm::ConstantInt::get(CGM.IntTy, flags.getBitMask());
1063 fields[2] = llvm::Constant::getNullValue(CGM.IntTy);
1066 fields[3] = blockFn;
1069 fields[4] = buildBlockDescriptor(CGM, blockInfo);
1071 llvm::Constant *init = llvm::ConstantStruct::getAnon(fields);
1073 llvm::GlobalVariable *literal =
1074 new llvm::GlobalVariable(CGM.getModule(),
1077 llvm::GlobalVariable::InternalLinkage,
1079 "__block_literal_global");
1080 literal->setAlignment(blockInfo.BlockAlign.getQuantity());
1082 // Return a constant of the appropriately-casted type.
1083 llvm::Type *requiredType =
1084 CGM.getTypes().ConvertType(blockInfo.getBlockExpr()->getType());
1085 return llvm::ConstantExpr::getBitCast(literal, requiredType);
1089 CodeGenFunction::GenerateBlockFunction(GlobalDecl GD,
1090 const CGBlockInfo &blockInfo,
1091 const DeclMapTy &ldm,
1092 bool IsLambdaConversionToBlock) {
1093 const BlockDecl *blockDecl = blockInfo.getBlockDecl();
1097 BlockInfo = &blockInfo;
1099 // Arrange for local static and local extern declarations to appear
1100 // to be local to this function as well, in case they're directly
1101 // referenced in a block.
1102 for (DeclMapTy::const_iterator i = ldm.begin(), e = ldm.end(); i != e; ++i) {
1103 const auto *var = dyn_cast<VarDecl>(i->first);
1104 if (var && !var->hasLocalStorage())
1105 LocalDeclMap[var] = i->second;
1108 // Begin building the function declaration.
1110 // Build the argument list.
1111 FunctionArgList args;
1113 // The first argument is the block pointer. Just take it as a void*
1114 // and cast it later.
1115 QualType selfTy = getContext().VoidPtrTy;
1116 IdentifierInfo *II = &CGM.getContext().Idents.get(".block_descriptor");
1118 ImplicitParamDecl selfDecl(getContext(), const_cast<BlockDecl*>(blockDecl),
1119 SourceLocation(), II, selfTy);
1120 args.push_back(&selfDecl);
1122 // Now add the rest of the parameters.
1123 for (auto i : blockDecl->params())
1126 // Create the function declaration.
1127 const FunctionProtoType *fnType = blockInfo.getBlockExpr()->getFunctionType();
1128 const CGFunctionInfo &fnInfo = CGM.getTypes().arrangeFreeFunctionDeclaration(
1129 fnType->getReturnType(), args, fnType->getExtInfo(),
1130 fnType->isVariadic());
1131 if (CGM.ReturnSlotInterferesWithArgs(fnInfo))
1132 blockInfo.UsesStret = true;
1134 llvm::FunctionType *fnLLVMType = CGM.getTypes().GetFunctionType(fnInfo);
1136 StringRef name = CGM.getBlockMangledName(GD, blockDecl);
1137 llvm::Function *fn = llvm::Function::Create(
1138 fnLLVMType, llvm::GlobalValue::InternalLinkage, name, &CGM.getModule());
1139 CGM.SetInternalFunctionAttributes(blockDecl, fn, fnInfo);
1141 // Begin generating the function.
1142 StartFunction(blockDecl, fnType->getReturnType(), fn, fnInfo, args,
1143 blockDecl->getLocation(),
1144 blockInfo.getBlockExpr()->getBody()->getLocStart());
1146 // Okay. Undo some of what StartFunction did.
1148 // Pull the 'self' reference out of the local decl map.
1149 llvm::Value *blockAddr = LocalDeclMap[&selfDecl];
1150 LocalDeclMap.erase(&selfDecl);
1151 BlockPointer = Builder.CreateBitCast(blockAddr,
1152 blockInfo.StructureType->getPointerTo(),
1154 // At -O0 we generate an explicit alloca for the BlockPointer, so the RA
1155 // won't delete the dbg.declare intrinsics for captured variables.
1156 llvm::Value *BlockPointerDbgLoc = BlockPointer;
1157 if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
1158 // Allocate a stack slot for it, so we can point the debugger to it
1159 llvm::AllocaInst *Alloca = CreateTempAlloca(BlockPointer->getType(),
1161 unsigned Align = getContext().getDeclAlign(&selfDecl).getQuantity();
1162 Alloca->setAlignment(Align);
1163 // Set the DebugLocation to empty, so the store is recognized as a
1164 // frame setup instruction by llvm::DwarfDebug::beginFunction().
1165 NoLocation NL(*this, Builder);
1166 Builder.CreateAlignedStore(BlockPointer, Alloca, Align);
1167 BlockPointerDbgLoc = Alloca;
1170 // If we have a C++ 'this' reference, go ahead and force it into
1172 if (blockDecl->capturesCXXThis()) {
1173 llvm::Value *addr = Builder.CreateStructGEP(BlockPointer,
1174 blockInfo.CXXThisIndex,
1175 "block.captured-this");
1176 CXXThisValue = Builder.CreateLoad(addr, "this");
1179 // Also force all the constant captures.
1180 for (const auto &CI : blockDecl->captures()) {
1181 const VarDecl *variable = CI.getVariable();
1182 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
1183 if (!capture.isConstant()) continue;
1185 unsigned align = getContext().getDeclAlign(variable).getQuantity();
1187 llvm::AllocaInst *alloca =
1188 CreateMemTemp(variable->getType(), "block.captured-const");
1189 alloca->setAlignment(align);
1191 Builder.CreateAlignedStore(capture.getConstant(), alloca, align);
1193 LocalDeclMap[variable] = alloca;
1196 // Save a spot to insert the debug information for all the DeclRefExprs.
1197 llvm::BasicBlock *entry = Builder.GetInsertBlock();
1198 llvm::BasicBlock::iterator entry_ptr = Builder.GetInsertPoint();
1201 if (IsLambdaConversionToBlock)
1202 EmitLambdaBlockInvokeBody();
1204 PGO.assignRegionCounters(blockDecl, fn);
1205 RegionCounter Cnt = getPGORegionCounter(blockDecl->getBody());
1206 Cnt.beginRegion(Builder);
1207 EmitStmt(blockDecl->getBody());
1208 PGO.emitInstrumentationData();
1209 PGO.destroyRegionCounters();
1212 // Remember where we were...
1213 llvm::BasicBlock *resume = Builder.GetInsertBlock();
1215 // Go back to the entry.
1217 Builder.SetInsertPoint(entry, entry_ptr);
1219 // Emit debug information for all the DeclRefExprs.
1220 // FIXME: also for 'this'
1221 if (CGDebugInfo *DI = getDebugInfo()) {
1222 for (const auto &CI : blockDecl->captures()) {
1223 const VarDecl *variable = CI.getVariable();
1224 DI->EmitLocation(Builder, variable->getLocation());
1226 if (CGM.getCodeGenOpts().getDebugInfo()
1227 >= CodeGenOptions::LimitedDebugInfo) {
1228 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
1229 if (capture.isConstant()) {
1230 DI->EmitDeclareOfAutoVariable(variable, LocalDeclMap[variable],
1235 DI->EmitDeclareOfBlockDeclRefVariable(variable, BlockPointerDbgLoc,
1236 Builder, blockInfo);
1239 // Recover location if it was changed in the above loop.
1240 DI->EmitLocation(Builder,
1241 cast<CompoundStmt>(blockDecl->getBody())->getRBracLoc());
1244 // And resume where we left off.
1245 if (resume == nullptr)
1246 Builder.ClearInsertionPoint();
1248 Builder.SetInsertPoint(resume);
1250 FinishFunction(cast<CompoundStmt>(blockDecl->getBody())->getRBracLoc());
1256 notes.push_back(HelperInfo());
1257 HelperInfo ¬e = notes.back();
1258 note.index = capture.getIndex();
1259 note.RequiresCopying = (ci->hasCopyExpr() || BlockRequiresCopying(type));
1260 note.cxxbar_import = ci->getCopyExpr();
1262 if (ci->isByRef()) {
1263 note.flag = BLOCK_FIELD_IS_BYREF;
1264 if (type.isObjCGCWeak())
1265 note.flag |= BLOCK_FIELD_IS_WEAK;
1266 } else if (type->isBlockPointerType()) {
1267 note.flag = BLOCK_FIELD_IS_BLOCK;
1269 note.flag = BLOCK_FIELD_IS_OBJECT;
1274 /// Generate the copy-helper function for a block closure object:
1275 /// static void block_copy_helper(block_t *dst, block_t *src);
1276 /// The runtime will have previously initialized 'dst' by doing a
1277 /// bit-copy of 'src'.
1279 /// Note that this copies an entire block closure object to the heap;
1280 /// it should not be confused with a 'byref copy helper', which moves
1281 /// the contents of an individual __block variable to the heap.
1283 CodeGenFunction::GenerateCopyHelperFunction(const CGBlockInfo &blockInfo) {
1284 ASTContext &C = getContext();
1286 FunctionArgList args;
1287 ImplicitParamDecl dstDecl(getContext(), nullptr, SourceLocation(), nullptr,
1289 args.push_back(&dstDecl);
1290 ImplicitParamDecl srcDecl(getContext(), nullptr, SourceLocation(), nullptr,
1292 args.push_back(&srcDecl);
1294 const CGFunctionInfo &FI = CGM.getTypes().arrangeFreeFunctionDeclaration(
1295 C.VoidTy, args, FunctionType::ExtInfo(), /*variadic=*/false);
1297 // FIXME: it would be nice if these were mergeable with things with
1298 // identical semantics.
1299 llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI);
1301 llvm::Function *Fn =
1302 llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
1303 "__copy_helper_block_", &CGM.getModule());
1306 = &CGM.getContext().Idents.get("__copy_helper_block_");
1308 FunctionDecl *FD = FunctionDecl::Create(C,
1309 C.getTranslationUnitDecl(),
1311 SourceLocation(), II, C.VoidTy,
1315 // Create a scope with an artificial location for the body of this function.
1316 ArtificialLocation AL(*this, Builder);
1317 StartFunction(FD, C.VoidTy, Fn, FI, args);
1320 llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo();
1322 llvm::Value *src = GetAddrOfLocalVar(&srcDecl);
1323 src = Builder.CreateLoad(src);
1324 src = Builder.CreateBitCast(src, structPtrTy, "block.source");
1326 llvm::Value *dst = GetAddrOfLocalVar(&dstDecl);
1327 dst = Builder.CreateLoad(dst);
1328 dst = Builder.CreateBitCast(dst, structPtrTy, "block.dest");
1330 const BlockDecl *blockDecl = blockInfo.getBlockDecl();
1332 for (const auto &CI : blockDecl->captures()) {
1333 const VarDecl *variable = CI.getVariable();
1334 QualType type = variable->getType();
1336 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
1337 if (capture.isConstant()) continue;
1339 const Expr *copyExpr = CI.getCopyExpr();
1340 BlockFieldFlags flags;
1342 bool useARCWeakCopy = false;
1343 bool useARCStrongCopy = false;
1346 assert(!CI.isByRef());
1347 // don't bother computing flags
1349 } else if (CI.isByRef()) {
1350 flags = BLOCK_FIELD_IS_BYREF;
1351 if (type.isObjCGCWeak())
1352 flags |= BLOCK_FIELD_IS_WEAK;
1354 } else if (type->isObjCRetainableType()) {
1355 flags = BLOCK_FIELD_IS_OBJECT;
1356 bool isBlockPointer = type->isBlockPointerType();
1358 flags = BLOCK_FIELD_IS_BLOCK;
1360 // Special rules for ARC captures:
1361 if (getLangOpts().ObjCAutoRefCount) {
1362 Qualifiers qs = type.getQualifiers();
1364 // We need to register __weak direct captures with the runtime.
1365 if (qs.getObjCLifetime() == Qualifiers::OCL_Weak) {
1366 useARCWeakCopy = true;
1368 // We need to retain the copied value for __strong direct captures.
1369 } else if (qs.getObjCLifetime() == Qualifiers::OCL_Strong) {
1370 // If it's a block pointer, we have to copy the block and
1371 // assign that to the destination pointer, so we might as
1372 // well use _Block_object_assign. Otherwise we can avoid that.
1373 if (!isBlockPointer)
1374 useARCStrongCopy = true;
1376 // Otherwise the memcpy is fine.
1381 // Non-ARC captures of retainable pointers are strong and
1382 // therefore require a call to _Block_object_assign.
1390 unsigned index = capture.getIndex();
1391 llvm::Value *srcField = Builder.CreateStructGEP(src, index);
1392 llvm::Value *dstField = Builder.CreateStructGEP(dst, index);
1394 // If there's an explicit copy expression, we do that.
1396 EmitSynthesizedCXXCopyCtor(dstField, srcField, copyExpr);
1397 } else if (useARCWeakCopy) {
1398 EmitARCCopyWeak(dstField, srcField);
1400 llvm::Value *srcValue = Builder.CreateLoad(srcField, "blockcopy.src");
1401 if (useARCStrongCopy) {
1402 // At -O0, store null into the destination field (so that the
1403 // storeStrong doesn't over-release) and then call storeStrong.
1404 // This is a workaround to not having an initStrong call.
1405 if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
1406 auto *ty = cast<llvm::PointerType>(srcValue->getType());
1407 llvm::Value *null = llvm::ConstantPointerNull::get(ty);
1408 Builder.CreateStore(null, dstField);
1409 EmitARCStoreStrongCall(dstField, srcValue, true);
1411 // With optimization enabled, take advantage of the fact that
1412 // the blocks runtime guarantees a memcpy of the block data, and
1413 // just emit a retain of the src field.
1415 EmitARCRetainNonBlock(srcValue);
1417 // We don't need this anymore, so kill it. It's not quite
1418 // worth the annoyance to avoid creating it in the first place.
1419 cast<llvm::Instruction>(dstField)->eraseFromParent();
1422 srcValue = Builder.CreateBitCast(srcValue, VoidPtrTy);
1423 llvm::Value *dstAddr = Builder.CreateBitCast(dstField, VoidPtrTy);
1424 llvm::Value *args[] = {
1425 dstAddr, srcValue, llvm::ConstantInt::get(Int32Ty, flags.getBitMask())
1428 bool copyCanThrow = false;
1429 if (CI.isByRef() && variable->getType()->getAsCXXRecordDecl()) {
1430 const Expr *copyExpr =
1431 CGM.getContext().getBlockVarCopyInits(variable);
1433 copyCanThrow = true; // FIXME: reuse the noexcept logic
1438 EmitRuntimeCallOrInvoke(CGM.getBlockObjectAssign(), args);
1440 EmitNounwindRuntimeCall(CGM.getBlockObjectAssign(), args);
1448 return llvm::ConstantExpr::getBitCast(Fn, VoidPtrTy);
1451 /// Generate the destroy-helper function for a block closure object:
1452 /// static void block_destroy_helper(block_t *theBlock);
1454 /// Note that this destroys a heap-allocated block closure object;
1455 /// it should not be confused with a 'byref destroy helper', which
1456 /// destroys the heap-allocated contents of an individual __block
1459 CodeGenFunction::GenerateDestroyHelperFunction(const CGBlockInfo &blockInfo) {
1460 ASTContext &C = getContext();
1462 FunctionArgList args;
1463 ImplicitParamDecl srcDecl(getContext(), nullptr, SourceLocation(), nullptr,
1465 args.push_back(&srcDecl);
1467 const CGFunctionInfo &FI = CGM.getTypes().arrangeFreeFunctionDeclaration(
1468 C.VoidTy, args, FunctionType::ExtInfo(), /*variadic=*/false);
1470 // FIXME: We'd like to put these into a mergable by content, with
1471 // internal linkage.
1472 llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI);
1474 llvm::Function *Fn =
1475 llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
1476 "__destroy_helper_block_", &CGM.getModule());
1479 = &CGM.getContext().Idents.get("__destroy_helper_block_");
1481 FunctionDecl *FD = FunctionDecl::Create(C, C.getTranslationUnitDecl(),
1483 SourceLocation(), II, C.VoidTy,
1486 // Create a scope with an artificial location for the body of this function.
1487 ArtificialLocation AL(*this, Builder);
1488 StartFunction(FD, C.VoidTy, Fn, FI, args);
1491 llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo();
1493 llvm::Value *src = GetAddrOfLocalVar(&srcDecl);
1494 src = Builder.CreateLoad(src);
1495 src = Builder.CreateBitCast(src, structPtrTy, "block");
1497 const BlockDecl *blockDecl = blockInfo.getBlockDecl();
1499 CodeGenFunction::RunCleanupsScope cleanups(*this);
1501 for (const auto &CI : blockDecl->captures()) {
1502 const VarDecl *variable = CI.getVariable();
1503 QualType type = variable->getType();
1505 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
1506 if (capture.isConstant()) continue;
1508 BlockFieldFlags flags;
1509 const CXXDestructorDecl *dtor = nullptr;
1511 bool useARCWeakDestroy = false;
1512 bool useARCStrongDestroy = false;
1515 flags = BLOCK_FIELD_IS_BYREF;
1516 if (type.isObjCGCWeak())
1517 flags |= BLOCK_FIELD_IS_WEAK;
1518 } else if (const CXXRecordDecl *record = type->getAsCXXRecordDecl()) {
1519 if (record->hasTrivialDestructor())
1521 dtor = record->getDestructor();
1522 } else if (type->isObjCRetainableType()) {
1523 flags = BLOCK_FIELD_IS_OBJECT;
1524 if (type->isBlockPointerType())
1525 flags = BLOCK_FIELD_IS_BLOCK;
1527 // Special rules for ARC captures.
1528 if (getLangOpts().ObjCAutoRefCount) {
1529 Qualifiers qs = type.getQualifiers();
1531 // Don't generate special dispose logic for a captured object
1532 // unless it's __strong or __weak.
1533 if (!qs.hasStrongOrWeakObjCLifetime())
1536 // Support __weak direct captures.
1537 if (qs.getObjCLifetime() == Qualifiers::OCL_Weak)
1538 useARCWeakDestroy = true;
1540 // Tools really want us to use objc_storeStrong here.
1542 useARCStrongDestroy = true;
1548 unsigned index = capture.getIndex();
1549 llvm::Value *srcField = Builder.CreateStructGEP(src, index);
1551 // If there's an explicit copy expression, we do that.
1553 PushDestructorCleanup(dtor, srcField);
1555 // If this is a __weak capture, emit the release directly.
1556 } else if (useARCWeakDestroy) {
1557 EmitARCDestroyWeak(srcField);
1559 // Destroy strong objects with a call if requested.
1560 } else if (useARCStrongDestroy) {
1561 EmitARCDestroyStrong(srcField, ARCImpreciseLifetime);
1563 // Otherwise we call _Block_object_dispose. It wouldn't be too
1564 // hard to just emit this as a cleanup if we wanted to make sure
1565 // that things were done in reverse.
1567 llvm::Value *value = Builder.CreateLoad(srcField);
1568 value = Builder.CreateBitCast(value, VoidPtrTy);
1569 BuildBlockRelease(value, flags);
1573 cleanups.ForceCleanup();
1577 return llvm::ConstantExpr::getBitCast(Fn, VoidPtrTy);
1582 /// Emits the copy/dispose helper functions for a __block object of id type.
1583 class ObjectByrefHelpers : public CodeGenModule::ByrefHelpers {
1584 BlockFieldFlags Flags;
1587 ObjectByrefHelpers(CharUnits alignment, BlockFieldFlags flags)
1588 : ByrefHelpers(alignment), Flags(flags) {}
1590 void emitCopy(CodeGenFunction &CGF, llvm::Value *destField,
1591 llvm::Value *srcField) override {
1592 destField = CGF.Builder.CreateBitCast(destField, CGF.VoidPtrTy);
1594 srcField = CGF.Builder.CreateBitCast(srcField, CGF.VoidPtrPtrTy);
1595 llvm::Value *srcValue = CGF.Builder.CreateLoad(srcField);
1597 unsigned flags = (Flags | BLOCK_BYREF_CALLER).getBitMask();
1599 llvm::Value *flagsVal = llvm::ConstantInt::get(CGF.Int32Ty, flags);
1600 llvm::Value *fn = CGF.CGM.getBlockObjectAssign();
1602 llvm::Value *args[] = { destField, srcValue, flagsVal };
1603 CGF.EmitNounwindRuntimeCall(fn, args);
1606 void emitDispose(CodeGenFunction &CGF, llvm::Value *field) override {
1607 field = CGF.Builder.CreateBitCast(field, CGF.Int8PtrTy->getPointerTo(0));
1608 llvm::Value *value = CGF.Builder.CreateLoad(field);
1610 CGF.BuildBlockRelease(value, Flags | BLOCK_BYREF_CALLER);
1613 void profileImpl(llvm::FoldingSetNodeID &id) const override {
1614 id.AddInteger(Flags.getBitMask());
1618 /// Emits the copy/dispose helpers for an ARC __block __weak variable.
1619 class ARCWeakByrefHelpers : public CodeGenModule::ByrefHelpers {
1621 ARCWeakByrefHelpers(CharUnits alignment) : ByrefHelpers(alignment) {}
1623 void emitCopy(CodeGenFunction &CGF, llvm::Value *destField,
1624 llvm::Value *srcField) override {
1625 CGF.EmitARCMoveWeak(destField, srcField);
1628 void emitDispose(CodeGenFunction &CGF, llvm::Value *field) override {
1629 CGF.EmitARCDestroyWeak(field);
1632 void profileImpl(llvm::FoldingSetNodeID &id) const override {
1633 // 0 is distinguishable from all pointers and byref flags
1638 /// Emits the copy/dispose helpers for an ARC __block __strong variable
1639 /// that's not of block-pointer type.
1640 class ARCStrongByrefHelpers : public CodeGenModule::ByrefHelpers {
1642 ARCStrongByrefHelpers(CharUnits alignment) : ByrefHelpers(alignment) {}
1644 void emitCopy(CodeGenFunction &CGF, llvm::Value *destField,
1645 llvm::Value *srcField) override {
1646 // Do a "move" by copying the value and then zeroing out the old
1649 llvm::LoadInst *value = CGF.Builder.CreateLoad(srcField);
1650 value->setAlignment(Alignment.getQuantity());
1653 llvm::ConstantPointerNull::get(cast<llvm::PointerType>(value->getType()));
1655 if (CGF.CGM.getCodeGenOpts().OptimizationLevel == 0) {
1656 llvm::StoreInst *store = CGF.Builder.CreateStore(null, destField);
1657 store->setAlignment(Alignment.getQuantity());
1658 CGF.EmitARCStoreStrongCall(destField, value, /*ignored*/ true);
1659 CGF.EmitARCStoreStrongCall(srcField, null, /*ignored*/ true);
1662 llvm::StoreInst *store = CGF.Builder.CreateStore(value, destField);
1663 store->setAlignment(Alignment.getQuantity());
1665 store = CGF.Builder.CreateStore(null, srcField);
1666 store->setAlignment(Alignment.getQuantity());
1669 void emitDispose(CodeGenFunction &CGF, llvm::Value *field) override {
1670 CGF.EmitARCDestroyStrong(field, ARCImpreciseLifetime);
1673 void profileImpl(llvm::FoldingSetNodeID &id) const override {
1674 // 1 is distinguishable from all pointers and byref flags
1679 /// Emits the copy/dispose helpers for an ARC __block __strong
1680 /// variable that's of block-pointer type.
1681 class ARCStrongBlockByrefHelpers : public CodeGenModule::ByrefHelpers {
1683 ARCStrongBlockByrefHelpers(CharUnits alignment) : ByrefHelpers(alignment) {}
1685 void emitCopy(CodeGenFunction &CGF, llvm::Value *destField,
1686 llvm::Value *srcField) override {
1687 // Do the copy with objc_retainBlock; that's all that
1688 // _Block_object_assign would do anyway, and we'd have to pass the
1689 // right arguments to make sure it doesn't get no-op'ed.
1690 llvm::LoadInst *oldValue = CGF.Builder.CreateLoad(srcField);
1691 oldValue->setAlignment(Alignment.getQuantity());
1693 llvm::Value *copy = CGF.EmitARCRetainBlock(oldValue, /*mandatory*/ true);
1695 llvm::StoreInst *store = CGF.Builder.CreateStore(copy, destField);
1696 store->setAlignment(Alignment.getQuantity());
1699 void emitDispose(CodeGenFunction &CGF, llvm::Value *field) override {
1700 CGF.EmitARCDestroyStrong(field, ARCImpreciseLifetime);
1703 void profileImpl(llvm::FoldingSetNodeID &id) const override {
1704 // 2 is distinguishable from all pointers and byref flags
1709 /// Emits the copy/dispose helpers for a __block variable with a
1710 /// nontrivial copy constructor or destructor.
1711 class CXXByrefHelpers : public CodeGenModule::ByrefHelpers {
1713 const Expr *CopyExpr;
1716 CXXByrefHelpers(CharUnits alignment, QualType type,
1717 const Expr *copyExpr)
1718 : ByrefHelpers(alignment), VarType(type), CopyExpr(copyExpr) {}
1720 bool needsCopy() const override { return CopyExpr != nullptr; }
1721 void emitCopy(CodeGenFunction &CGF, llvm::Value *destField,
1722 llvm::Value *srcField) override {
1723 if (!CopyExpr) return;
1724 CGF.EmitSynthesizedCXXCopyCtor(destField, srcField, CopyExpr);
1727 void emitDispose(CodeGenFunction &CGF, llvm::Value *field) override {
1728 EHScopeStack::stable_iterator cleanupDepth = CGF.EHStack.stable_begin();
1729 CGF.PushDestructorCleanup(VarType, field);
1730 CGF.PopCleanupBlocks(cleanupDepth);
1733 void profileImpl(llvm::FoldingSetNodeID &id) const override {
1734 id.AddPointer(VarType.getCanonicalType().getAsOpaquePtr());
1737 } // end anonymous namespace
1739 static llvm::Constant *
1740 generateByrefCopyHelper(CodeGenFunction &CGF,
1741 llvm::StructType &byrefType,
1742 unsigned valueFieldIndex,
1743 CodeGenModule::ByrefHelpers &byrefInfo) {
1744 ASTContext &Context = CGF.getContext();
1746 QualType R = Context.VoidTy;
1748 FunctionArgList args;
1749 ImplicitParamDecl dst(CGF.getContext(), nullptr, SourceLocation(), nullptr,
1751 args.push_back(&dst);
1753 ImplicitParamDecl src(CGF.getContext(), nullptr, SourceLocation(), nullptr,
1755 args.push_back(&src);
1757 const CGFunctionInfo &FI = CGF.CGM.getTypes().arrangeFreeFunctionDeclaration(
1758 R, args, FunctionType::ExtInfo(), /*variadic=*/false);
1760 CodeGenTypes &Types = CGF.CGM.getTypes();
1761 llvm::FunctionType *LTy = Types.GetFunctionType(FI);
1763 // FIXME: We'd like to put these into a mergable by content, with
1764 // internal linkage.
1765 llvm::Function *Fn =
1766 llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
1767 "__Block_byref_object_copy_", &CGF.CGM.getModule());
1770 = &Context.Idents.get("__Block_byref_object_copy_");
1772 FunctionDecl *FD = FunctionDecl::Create(Context,
1773 Context.getTranslationUnitDecl(),
1775 SourceLocation(), II, R, nullptr,
1779 CGF.StartFunction(FD, R, Fn, FI, args);
1781 if (byrefInfo.needsCopy()) {
1782 llvm::Type *byrefPtrType = byrefType.getPointerTo(0);
1785 llvm::Value *destField = CGF.GetAddrOfLocalVar(&dst);
1786 destField = CGF.Builder.CreateLoad(destField);
1787 destField = CGF.Builder.CreateBitCast(destField, byrefPtrType);
1788 destField = CGF.Builder.CreateStructGEP(destField, valueFieldIndex, "x");
1791 llvm::Value *srcField = CGF.GetAddrOfLocalVar(&src);
1792 srcField = CGF.Builder.CreateLoad(srcField);
1793 srcField = CGF.Builder.CreateBitCast(srcField, byrefPtrType);
1794 srcField = CGF.Builder.CreateStructGEP(srcField, valueFieldIndex, "x");
1796 byrefInfo.emitCopy(CGF, destField, srcField);
1799 CGF.FinishFunction();
1801 return llvm::ConstantExpr::getBitCast(Fn, CGF.Int8PtrTy);
1804 /// Build the copy helper for a __block variable.
1805 static llvm::Constant *buildByrefCopyHelper(CodeGenModule &CGM,
1806 llvm::StructType &byrefType,
1807 unsigned byrefValueIndex,
1808 CodeGenModule::ByrefHelpers &info) {
1809 CodeGenFunction CGF(CGM);
1810 return generateByrefCopyHelper(CGF, byrefType, byrefValueIndex, info);
1813 /// Generate code for a __block variable's dispose helper.
1814 static llvm::Constant *
1815 generateByrefDisposeHelper(CodeGenFunction &CGF,
1816 llvm::StructType &byrefType,
1817 unsigned byrefValueIndex,
1818 CodeGenModule::ByrefHelpers &byrefInfo) {
1819 ASTContext &Context = CGF.getContext();
1820 QualType R = Context.VoidTy;
1822 FunctionArgList args;
1823 ImplicitParamDecl src(CGF.getContext(), nullptr, SourceLocation(), nullptr,
1825 args.push_back(&src);
1827 const CGFunctionInfo &FI = CGF.CGM.getTypes().arrangeFreeFunctionDeclaration(
1828 R, args, FunctionType::ExtInfo(), /*variadic=*/false);
1830 CodeGenTypes &Types = CGF.CGM.getTypes();
1831 llvm::FunctionType *LTy = Types.GetFunctionType(FI);
1833 // FIXME: We'd like to put these into a mergable by content, with
1834 // internal linkage.
1835 llvm::Function *Fn =
1836 llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
1837 "__Block_byref_object_dispose_",
1838 &CGF.CGM.getModule());
1841 = &Context.Idents.get("__Block_byref_object_dispose_");
1843 FunctionDecl *FD = FunctionDecl::Create(Context,
1844 Context.getTranslationUnitDecl(),
1846 SourceLocation(), II, R, nullptr,
1849 CGF.StartFunction(FD, R, Fn, FI, args);
1851 if (byrefInfo.needsDispose()) {
1852 llvm::Value *V = CGF.GetAddrOfLocalVar(&src);
1853 V = CGF.Builder.CreateLoad(V);
1854 V = CGF.Builder.CreateBitCast(V, byrefType.getPointerTo(0));
1855 V = CGF.Builder.CreateStructGEP(V, byrefValueIndex, "x");
1857 byrefInfo.emitDispose(CGF, V);
1860 CGF.FinishFunction();
1862 return llvm::ConstantExpr::getBitCast(Fn, CGF.Int8PtrTy);
1865 /// Build the dispose helper for a __block variable.
1866 static llvm::Constant *buildByrefDisposeHelper(CodeGenModule &CGM,
1867 llvm::StructType &byrefType,
1868 unsigned byrefValueIndex,
1869 CodeGenModule::ByrefHelpers &info) {
1870 CodeGenFunction CGF(CGM);
1871 return generateByrefDisposeHelper(CGF, byrefType, byrefValueIndex, info);
1874 /// Lazily build the copy and dispose helpers for a __block variable
1875 /// with the given information.
1876 template <class T> static T *buildByrefHelpers(CodeGenModule &CGM,
1877 llvm::StructType &byrefTy,
1878 unsigned byrefValueIndex,
1880 // Increase the field's alignment to be at least pointer alignment,
1881 // since the layout of the byref struct will guarantee at least that.
1882 byrefInfo.Alignment = std::max(byrefInfo.Alignment,
1883 CharUnits::fromQuantity(CGM.PointerAlignInBytes));
1885 llvm::FoldingSetNodeID id;
1886 byrefInfo.Profile(id);
1889 CodeGenModule::ByrefHelpers *node
1890 = CGM.ByrefHelpersCache.FindNodeOrInsertPos(id, insertPos);
1891 if (node) return static_cast<T*>(node);
1893 byrefInfo.CopyHelper =
1894 buildByrefCopyHelper(CGM, byrefTy, byrefValueIndex, byrefInfo);
1895 byrefInfo.DisposeHelper =
1896 buildByrefDisposeHelper(CGM, byrefTy, byrefValueIndex,byrefInfo);
1898 T *copy = new (CGM.getContext()) T(byrefInfo);
1899 CGM.ByrefHelpersCache.InsertNode(copy, insertPos);
1903 /// Build the copy and dispose helpers for the given __block variable
1904 /// emission. Places the helpers in the global cache. Returns null
1905 /// if no helpers are required.
1906 CodeGenModule::ByrefHelpers *
1907 CodeGenFunction::buildByrefHelpers(llvm::StructType &byrefType,
1908 const AutoVarEmission &emission) {
1909 const VarDecl &var = *emission.Variable;
1910 QualType type = var.getType();
1912 unsigned byrefValueIndex = getByRefValueLLVMField(&var);
1914 if (const CXXRecordDecl *record = type->getAsCXXRecordDecl()) {
1915 const Expr *copyExpr = CGM.getContext().getBlockVarCopyInits(&var);
1916 if (!copyExpr && record->hasTrivialDestructor()) return nullptr;
1918 CXXByrefHelpers byrefInfo(emission.Alignment, type, copyExpr);
1919 return ::buildByrefHelpers(CGM, byrefType, byrefValueIndex, byrefInfo);
1922 // Otherwise, if we don't have a retainable type, there's nothing to do.
1923 // that the runtime does extra copies.
1924 if (!type->isObjCRetainableType()) return nullptr;
1926 Qualifiers qs = type.getQualifiers();
1928 // If we have lifetime, that dominates.
1929 if (Qualifiers::ObjCLifetime lifetime = qs.getObjCLifetime()) {
1930 assert(getLangOpts().ObjCAutoRefCount);
1933 case Qualifiers::OCL_None: llvm_unreachable("impossible");
1935 // These are just bits as far as the runtime is concerned.
1936 case Qualifiers::OCL_ExplicitNone:
1937 case Qualifiers::OCL_Autoreleasing:
1940 // Tell the runtime that this is ARC __weak, called by the
1942 case Qualifiers::OCL_Weak: {
1943 ARCWeakByrefHelpers byrefInfo(emission.Alignment);
1944 return ::buildByrefHelpers(CGM, byrefType, byrefValueIndex, byrefInfo);
1947 // ARC __strong __block variables need to be retained.
1948 case Qualifiers::OCL_Strong:
1949 // Block pointers need to be copied, and there's no direct
1950 // transfer possible.
1951 if (type->isBlockPointerType()) {
1952 ARCStrongBlockByrefHelpers byrefInfo(emission.Alignment);
1953 return ::buildByrefHelpers(CGM, byrefType, byrefValueIndex, byrefInfo);
1955 // Otherwise, we transfer ownership of the retain from the stack
1958 ARCStrongByrefHelpers byrefInfo(emission.Alignment);
1959 return ::buildByrefHelpers(CGM, byrefType, byrefValueIndex, byrefInfo);
1962 llvm_unreachable("fell out of lifetime switch!");
1965 BlockFieldFlags flags;
1966 if (type->isBlockPointerType()) {
1967 flags |= BLOCK_FIELD_IS_BLOCK;
1968 } else if (CGM.getContext().isObjCNSObjectType(type) ||
1969 type->isObjCObjectPointerType()) {
1970 flags |= BLOCK_FIELD_IS_OBJECT;
1975 if (type.isObjCGCWeak())
1976 flags |= BLOCK_FIELD_IS_WEAK;
1978 ObjectByrefHelpers byrefInfo(emission.Alignment, flags);
1979 return ::buildByrefHelpers(CGM, byrefType, byrefValueIndex, byrefInfo);
1982 unsigned CodeGenFunction::getByRefValueLLVMField(const ValueDecl *VD) const {
1983 assert(ByRefValueInfo.count(VD) && "Did not find value!");
1985 return ByRefValueInfo.find(VD)->second.second;
1988 llvm::Value *CodeGenFunction::BuildBlockByrefAddress(llvm::Value *BaseAddr,
1990 llvm::Value *Loc = Builder.CreateStructGEP(BaseAddr, 1, "forwarding");
1991 Loc = Builder.CreateLoad(Loc);
1992 Loc = Builder.CreateStructGEP(Loc, getByRefValueLLVMField(V),
1993 V->getNameAsString());
1997 /// BuildByRefType - This routine changes a __block variable declared as T x
2002 /// void *__forwarding;
2003 /// int32_t __flags;
2005 /// void *__copy_helper; // only if needed
2006 /// void *__destroy_helper; // only if needed
2007 /// void *__byref_variable_layout;// only if needed
2008 /// char padding[X]; // only if needed
2012 llvm::Type *CodeGenFunction::BuildByRefType(const VarDecl *D) {
2013 std::pair<llvm::Type *, unsigned> &Info = ByRefValueInfo[D];
2017 QualType Ty = D->getType();
2019 SmallVector<llvm::Type *, 8> types;
2021 llvm::StructType *ByRefType =
2022 llvm::StructType::create(getLLVMContext(),
2023 "struct.__block_byref_" + D->getNameAsString());
2026 types.push_back(Int8PtrTy);
2028 // void *__forwarding;
2029 types.push_back(llvm::PointerType::getUnqual(ByRefType));
2032 types.push_back(Int32Ty);
2035 types.push_back(Int32Ty);
2036 // Note that this must match *exactly* the logic in buildByrefHelpers.
2037 bool HasCopyAndDispose = getContext().BlockRequiresCopying(Ty, D);
2038 if (HasCopyAndDispose) {
2039 /// void *__copy_helper;
2040 types.push_back(Int8PtrTy);
2042 /// void *__destroy_helper;
2043 types.push_back(Int8PtrTy);
2045 bool HasByrefExtendedLayout = false;
2046 Qualifiers::ObjCLifetime Lifetime;
2047 if (getContext().getByrefLifetime(Ty, Lifetime, HasByrefExtendedLayout) &&
2048 HasByrefExtendedLayout)
2049 /// void *__byref_variable_layout;
2050 types.push_back(Int8PtrTy);
2052 bool Packed = false;
2053 CharUnits Align = getContext().getDeclAlign(D);
2055 getContext().toCharUnitsFromBits(getTarget().getPointerAlign(0))) {
2056 // We have to insert padding.
2058 // The struct above has 2 32-bit integers.
2059 unsigned CurrentOffsetInBytes = 4 * 2;
2061 // And either 2, 3, 4 or 5 pointers.
2062 unsigned noPointers = 2;
2063 if (HasCopyAndDispose)
2065 if (HasByrefExtendedLayout)
2068 CurrentOffsetInBytes += noPointers * CGM.getDataLayout().getTypeAllocSize(Int8PtrTy);
2070 // Align the offset.
2071 unsigned AlignedOffsetInBytes =
2072 llvm::RoundUpToAlignment(CurrentOffsetInBytes, Align.getQuantity());
2074 unsigned NumPaddingBytes = AlignedOffsetInBytes - CurrentOffsetInBytes;
2075 if (NumPaddingBytes > 0) {
2076 llvm::Type *Ty = Int8Ty;
2077 // FIXME: We need a sema error for alignment larger than the minimum of
2078 // the maximal stack alignment and the alignment of malloc on the system.
2079 if (NumPaddingBytes > 1)
2080 Ty = llvm::ArrayType::get(Ty, NumPaddingBytes);
2082 types.push_back(Ty);
2084 // We want a packed struct.
2090 types.push_back(ConvertTypeForMem(Ty));
2092 ByRefType->setBody(types, Packed);
2094 Info.first = ByRefType;
2096 Info.second = types.size() - 1;
2101 /// Initialize the structural components of a __block variable, i.e.
2102 /// everything but the actual object.
2103 void CodeGenFunction::emitByrefStructureInit(const AutoVarEmission &emission) {
2104 // Find the address of the local.
2105 llvm::Value *addr = emission.Address;
2107 // That's an alloca of the byref structure type.
2108 llvm::StructType *byrefType = cast<llvm::StructType>(
2109 cast<llvm::PointerType>(addr->getType())->getElementType());
2111 // Build the byref helpers if necessary. This is null if we don't need any.
2112 CodeGenModule::ByrefHelpers *helpers =
2113 buildByrefHelpers(*byrefType, emission);
2115 const VarDecl &D = *emission.Variable;
2116 QualType type = D.getType();
2118 bool HasByrefExtendedLayout;
2119 Qualifiers::ObjCLifetime ByrefLifetime;
2120 bool ByRefHasLifetime =
2121 getContext().getByrefLifetime(type, ByrefLifetime, HasByrefExtendedLayout);
2125 // Initialize the 'isa', which is just 0 or 1.
2127 if (type.isObjCGCWeak())
2129 V = Builder.CreateIntToPtr(Builder.getInt32(isa), Int8PtrTy, "isa");
2130 Builder.CreateStore(V, Builder.CreateStructGEP(addr, 0, "byref.isa"));
2132 // Store the address of the variable into its own forwarding pointer.
2133 Builder.CreateStore(addr,
2134 Builder.CreateStructGEP(addr, 1, "byref.forwarding"));
2137 // c) the flags field is set to either 0 if no helper functions are
2138 // needed or BLOCK_BYREF_HAS_COPY_DISPOSE if they are,
2140 if (helpers) flags |= BLOCK_BYREF_HAS_COPY_DISPOSE;
2141 if (ByRefHasLifetime) {
2142 if (HasByrefExtendedLayout) flags |= BLOCK_BYREF_LAYOUT_EXTENDED;
2143 else switch (ByrefLifetime) {
2144 case Qualifiers::OCL_Strong:
2145 flags |= BLOCK_BYREF_LAYOUT_STRONG;
2147 case Qualifiers::OCL_Weak:
2148 flags |= BLOCK_BYREF_LAYOUT_WEAK;
2150 case Qualifiers::OCL_ExplicitNone:
2151 flags |= BLOCK_BYREF_LAYOUT_UNRETAINED;
2153 case Qualifiers::OCL_None:
2154 if (!type->isObjCObjectPointerType() && !type->isBlockPointerType())
2155 flags |= BLOCK_BYREF_LAYOUT_NON_OBJECT;
2160 if (CGM.getLangOpts().ObjCGCBitmapPrint) {
2161 printf("\n Inline flag for BYREF variable layout (%d):", flags.getBitMask());
2162 if (flags & BLOCK_BYREF_HAS_COPY_DISPOSE)
2163 printf(" BLOCK_BYREF_HAS_COPY_DISPOSE");
2164 if (flags & BLOCK_BYREF_LAYOUT_MASK) {
2165 BlockFlags ThisFlag(flags.getBitMask() & BLOCK_BYREF_LAYOUT_MASK);
2166 if (ThisFlag == BLOCK_BYREF_LAYOUT_EXTENDED)
2167 printf(" BLOCK_BYREF_LAYOUT_EXTENDED");
2168 if (ThisFlag == BLOCK_BYREF_LAYOUT_STRONG)
2169 printf(" BLOCK_BYREF_LAYOUT_STRONG");
2170 if (ThisFlag == BLOCK_BYREF_LAYOUT_WEAK)
2171 printf(" BLOCK_BYREF_LAYOUT_WEAK");
2172 if (ThisFlag == BLOCK_BYREF_LAYOUT_UNRETAINED)
2173 printf(" BLOCK_BYREF_LAYOUT_UNRETAINED");
2174 if (ThisFlag == BLOCK_BYREF_LAYOUT_NON_OBJECT)
2175 printf(" BLOCK_BYREF_LAYOUT_NON_OBJECT");
2181 Builder.CreateStore(llvm::ConstantInt::get(IntTy, flags.getBitMask()),
2182 Builder.CreateStructGEP(addr, 2, "byref.flags"));
2184 CharUnits byrefSize = CGM.GetTargetTypeStoreSize(byrefType);
2185 V = llvm::ConstantInt::get(IntTy, byrefSize.getQuantity());
2186 Builder.CreateStore(V, Builder.CreateStructGEP(addr, 3, "byref.size"));
2189 llvm::Value *copy_helper = Builder.CreateStructGEP(addr, 4);
2190 Builder.CreateStore(helpers->CopyHelper, copy_helper);
2192 llvm::Value *destroy_helper = Builder.CreateStructGEP(addr, 5);
2193 Builder.CreateStore(helpers->DisposeHelper, destroy_helper);
2195 if (ByRefHasLifetime && HasByrefExtendedLayout) {
2196 llvm::Constant* ByrefLayoutInfo = CGM.getObjCRuntime().BuildByrefLayout(CGM, type);
2197 llvm::Value *ByrefInfoAddr = Builder.CreateStructGEP(addr, helpers ? 6 : 4,
2199 // cast destination to pointer to source type.
2200 llvm::Type *DesTy = ByrefLayoutInfo->getType();
2201 DesTy = DesTy->getPointerTo();
2202 llvm::Value *BC = Builder.CreatePointerCast(ByrefInfoAddr, DesTy);
2203 Builder.CreateStore(ByrefLayoutInfo, BC);
2207 void CodeGenFunction::BuildBlockRelease(llvm::Value *V, BlockFieldFlags flags) {
2208 llvm::Value *F = CGM.getBlockObjectDispose();
2209 llvm::Value *args[] = {
2210 Builder.CreateBitCast(V, Int8PtrTy),
2211 llvm::ConstantInt::get(Int32Ty, flags.getBitMask())
2213 EmitNounwindRuntimeCall(F, args); // FIXME: throwing destructors?
2217 struct CallBlockRelease : EHScopeStack::Cleanup {
2219 CallBlockRelease(llvm::Value *Addr) : Addr(Addr) {}
2221 void Emit(CodeGenFunction &CGF, Flags flags) override {
2222 // Should we be passing FIELD_IS_WEAK here?
2223 CGF.BuildBlockRelease(Addr, BLOCK_FIELD_IS_BYREF);
2228 /// Enter a cleanup to destroy a __block variable. Note that this
2229 /// cleanup should be a no-op if the variable hasn't left the stack
2230 /// yet; if a cleanup is required for the variable itself, that needs
2231 /// to be done externally.
2232 void CodeGenFunction::enterByrefCleanup(const AutoVarEmission &emission) {
2233 // We don't enter this cleanup if we're in pure-GC mode.
2234 if (CGM.getLangOpts().getGC() == LangOptions::GCOnly)
2237 EHStack.pushCleanup<CallBlockRelease>(NormalAndEHCleanup, emission.Address);
2240 /// Adjust the declaration of something from the blocks API.
2241 static void configureBlocksRuntimeObject(CodeGenModule &CGM,
2242 llvm::Constant *C) {
2243 if (!CGM.getLangOpts().BlocksRuntimeOptional) return;
2245 auto *GV = cast<llvm::GlobalValue>(C->stripPointerCasts());
2246 if (GV->isDeclaration() && GV->hasExternalLinkage())
2247 GV->setLinkage(llvm::GlobalValue::ExternalWeakLinkage);
2250 llvm::Constant *CodeGenModule::getBlockObjectDispose() {
2251 if (BlockObjectDispose)
2252 return BlockObjectDispose;
2254 llvm::Type *args[] = { Int8PtrTy, Int32Ty };
2255 llvm::FunctionType *fty
2256 = llvm::FunctionType::get(VoidTy, args, false);
2257 BlockObjectDispose = CreateRuntimeFunction(fty, "_Block_object_dispose");
2258 configureBlocksRuntimeObject(*this, BlockObjectDispose);
2259 return BlockObjectDispose;
2262 llvm::Constant *CodeGenModule::getBlockObjectAssign() {
2263 if (BlockObjectAssign)
2264 return BlockObjectAssign;
2266 llvm::Type *args[] = { Int8PtrTy, Int8PtrTy, Int32Ty };
2267 llvm::FunctionType *fty
2268 = llvm::FunctionType::get(VoidTy, args, false);
2269 BlockObjectAssign = CreateRuntimeFunction(fty, "_Block_object_assign");
2270 configureBlocksRuntimeObject(*this, BlockObjectAssign);
2271 return BlockObjectAssign;
2274 llvm::Constant *CodeGenModule::getNSConcreteGlobalBlock() {
2275 if (NSConcreteGlobalBlock)
2276 return NSConcreteGlobalBlock;
2278 NSConcreteGlobalBlock = GetOrCreateLLVMGlobal("_NSConcreteGlobalBlock",
2279 Int8PtrTy->getPointerTo(),
2281 configureBlocksRuntimeObject(*this, NSConcreteGlobalBlock);
2282 return NSConcreteGlobalBlock;
2285 llvm::Constant *CodeGenModule::getNSConcreteStackBlock() {
2286 if (NSConcreteStackBlock)
2287 return NSConcreteStackBlock;
2289 NSConcreteStackBlock = GetOrCreateLLVMGlobal("_NSConcreteStackBlock",
2290 Int8PtrTy->getPointerTo(),
2292 configureBlocksRuntimeObject(*this, NSConcreteStackBlock);
2293 return NSConcreteStackBlock;