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 //===----------------------------------------------------------------------===//
14 #include "CGDebugInfo.h"
15 #include "CodeGenFunction.h"
16 #include "CGObjCRuntime.h"
17 #include "CodeGenModule.h"
19 #include "clang/AST/DeclObjC.h"
20 #include "llvm/Module.h"
21 #include "llvm/ADT/SmallSet.h"
22 #include "llvm/Target/TargetData.h"
25 using namespace clang;
26 using namespace CodeGen;
28 CGBlockInfo::CGBlockInfo(const BlockExpr *blockExpr, const char *N)
29 : Name(N), CXXThisIndex(0), CanBeGlobal(false), NeedsCopyDispose(false),
30 HasCXXObject(false), UsesStret(false), StructureType(0), Block(blockExpr) {
32 // Skip asm prefix, if any.
33 if (Name && Name[0] == '\01')
37 // Anchor the vtable to this translation unit.
38 CodeGenModule::ByrefHelpers::~ByrefHelpers() {}
40 /// Build the given block as a global block.
41 static llvm::Constant *buildGlobalBlock(CodeGenModule &CGM,
42 const CGBlockInfo &blockInfo,
43 llvm::Constant *blockFn);
45 /// Build the helper function to copy a block.
46 static llvm::Constant *buildCopyHelper(CodeGenModule &CGM,
47 const CGBlockInfo &blockInfo) {
48 return CodeGenFunction(CGM).GenerateCopyHelperFunction(blockInfo);
51 /// Build the helper function to dipose of a block.
52 static llvm::Constant *buildDisposeHelper(CodeGenModule &CGM,
53 const CGBlockInfo &blockInfo) {
54 return CodeGenFunction(CGM).GenerateDestroyHelperFunction(blockInfo);
57 /// Build the block descriptor constant for a block.
58 static llvm::Constant *buildBlockDescriptor(CodeGenModule &CGM,
59 const CGBlockInfo &blockInfo) {
60 ASTContext &C = CGM.getContext();
62 const llvm::Type *ulong = CGM.getTypes().ConvertType(C.UnsignedLongTy);
63 const llvm::Type *i8p = CGM.getTypes().ConvertType(C.VoidPtrTy);
65 llvm::SmallVector<llvm::Constant*, 6> elements;
68 elements.push_back(llvm::ConstantInt::get(ulong, 0));
71 // FIXME: What is the right way to say this doesn't fit? We should give
72 // a user diagnostic in that case. Better fix would be to change the
74 elements.push_back(llvm::ConstantInt::get(ulong,
75 blockInfo.BlockSize.getQuantity()));
77 // Optional copy/dispose helpers.
78 if (blockInfo.NeedsCopyDispose) {
79 // copy_func_helper_decl
80 elements.push_back(buildCopyHelper(CGM, blockInfo));
83 elements.push_back(buildDisposeHelper(CGM, blockInfo));
86 // Signature. Mandatory ObjC-style method descriptor @encode sequence.
87 std::string typeAtEncoding =
88 CGM.getContext().getObjCEncodingForBlock(blockInfo.getBlockExpr());
89 elements.push_back(llvm::ConstantExpr::getBitCast(
90 CGM.GetAddrOfConstantCString(typeAtEncoding), i8p));
93 if (C.getLangOptions().ObjC1)
94 elements.push_back(CGM.getObjCRuntime().BuildGCBlockLayout(CGM, blockInfo));
96 elements.push_back(llvm::Constant::getNullValue(i8p));
98 llvm::Constant *init = llvm::ConstantStruct::getAnon(elements);
100 llvm::GlobalVariable *global =
101 new llvm::GlobalVariable(CGM.getModule(), init->getType(), true,
102 llvm::GlobalValue::InternalLinkage,
103 init, "__block_descriptor_tmp");
105 return llvm::ConstantExpr::getBitCast(global, CGM.getBlockDescriptorType());
109 Purely notional variadic template describing the layout of a block.
111 template <class _ResultType, class... _ParamTypes, class... _CaptureTypes>
112 struct Block_literal {
113 /// Initialized to one of:
114 /// extern void *_NSConcreteStackBlock[];
115 /// extern void *_NSConcreteGlobalBlock[];
117 /// In theory, we could start one off malloc'ed by setting
118 /// BLOCK_NEEDS_FREE, giving it a refcount of 1, and using
120 /// extern void *_NSConcreteMallocBlock[];
121 struct objc_class *isa;
123 /// These are the flags (with corresponding bit number) that the
124 /// compiler is actually supposed to know about.
125 /// 25. BLOCK_HAS_COPY_DISPOSE - indicates that the block
126 /// descriptor provides copy and dispose helper functions
127 /// 26. BLOCK_HAS_CXX_OBJ - indicates that there's a captured
128 /// object with a nontrivial destructor or copy constructor
129 /// 28. BLOCK_IS_GLOBAL - indicates that the block is allocated
131 /// 29. BLOCK_USE_STRET - indicates that the block function
132 /// uses stret, which objc_msgSend needs to know about
133 /// 30. BLOCK_HAS_SIGNATURE - indicates that the block has an
134 /// @encoded signature string
135 /// And we're not supposed to manipulate these:
136 /// 24. BLOCK_NEEDS_FREE - indicates that the block has been moved
137 /// to malloc'ed memory
138 /// 27. BLOCK_IS_GC - indicates that the block has been moved to
139 /// to GC-allocated memory
140 /// Additionally, the bottom 16 bits are a reference count which
141 /// should be zero on the stack.
144 /// Reserved; should be zero-initialized.
147 /// Function pointer generated from block literal.
148 _ResultType (*invoke)(Block_literal *, _ParamTypes...);
150 /// Block description metadata generated from block literal.
151 struct Block_descriptor *block_descriptor;
153 /// Captured values follow.
154 _CapturesTypes captures...;
158 /// The number of fields in a block header.
159 const unsigned BlockHeaderSize = 5;
162 /// A chunk of data that we actually have to capture in the block.
163 struct BlockLayoutChunk {
166 const BlockDecl::Capture *Capture; // null for 'this'
169 BlockLayoutChunk(CharUnits align, CharUnits size,
170 const BlockDecl::Capture *capture,
172 : Alignment(align), Size(size), Capture(capture), Type(type) {}
174 /// Tell the block info that this chunk has the given field index.
175 void setIndex(CGBlockInfo &info, unsigned index) {
177 info.CXXThisIndex = index;
179 info.Captures[Capture->getVariable()]
180 = CGBlockInfo::Capture::makeIndex(index);
184 /// Order by descending alignment.
185 bool operator<(const BlockLayoutChunk &left, const BlockLayoutChunk &right) {
186 return left.Alignment > right.Alignment;
190 /// Determines if the given type is safe for constant capture in C++.
191 static bool isSafeForCXXConstantCapture(QualType type) {
192 const RecordType *recordType =
193 type->getBaseElementTypeUnsafe()->getAs<RecordType>();
195 // Only records can be unsafe.
196 if (!recordType) return true;
198 const CXXRecordDecl *record = cast<CXXRecordDecl>(recordType->getDecl());
200 // Maintain semantics for classes with non-trivial dtors or copy ctors.
201 if (!record->hasTrivialDestructor()) return false;
202 if (!record->hasTrivialCopyConstructor()) return false;
204 // Otherwise, we just have to make sure there aren't any mutable
205 // fields that might have changed since initialization.
206 return !record->hasMutableFields();
209 /// It is illegal to modify a const object after initialization.
210 /// Therefore, if a const object has a constant initializer, we don't
211 /// actually need to keep storage for it in the block; we'll just
212 /// rematerialize it at the start of the block function. This is
213 /// acceptable because we make no promises about address stability of
214 /// captured variables.
215 static llvm::Constant *tryCaptureAsConstant(CodeGenModule &CGM,
216 const VarDecl *var) {
217 QualType type = var->getType();
219 // We can only do this if the variable is const.
220 if (!type.isConstQualified()) return 0;
222 // Furthermore, in C++ we have to worry about mutable fields:
223 // C++ [dcl.type.cv]p4:
224 // Except that any class member declared mutable can be
225 // modified, any attempt to modify a const object during its
226 // lifetime results in undefined behavior.
227 if (CGM.getLangOptions().CPlusPlus && !isSafeForCXXConstantCapture(type))
230 // If the variable doesn't have any initializer (shouldn't this be
231 // invalid?), it's not clear what we should do. Maybe capture as
233 const Expr *init = var->getInit();
236 return CGM.EmitConstantExpr(init, var->getType());
239 /// Get the low bit of a nonzero character count. This is the
240 /// alignment of the nth byte if the 0th byte is universally aligned.
241 static CharUnits getLowBit(CharUnits v) {
242 return CharUnits::fromQuantity(v.getQuantity() & (~v.getQuantity() + 1));
245 static void initializeForBlockHeader(CodeGenModule &CGM, CGBlockInfo &info,
246 llvm::SmallVectorImpl<llvm::Type*> &elementTypes) {
247 ASTContext &C = CGM.getContext();
249 // The header is basically a 'struct { void *; int; int; void *; void *; }'.
250 CharUnits ptrSize, ptrAlign, intSize, intAlign;
251 llvm::tie(ptrSize, ptrAlign) = C.getTypeInfoInChars(C.VoidPtrTy);
252 llvm::tie(intSize, intAlign) = C.getTypeInfoInChars(C.IntTy);
254 // Are there crazy embedded platforms where this isn't true?
255 assert(intSize <= ptrSize && "layout assumptions horribly violated");
257 CharUnits headerSize = ptrSize;
258 if (2 * intSize < ptrAlign) headerSize += ptrSize;
259 else headerSize += 2 * intSize;
260 headerSize += 2 * ptrSize;
262 info.BlockAlign = ptrAlign;
263 info.BlockSize = headerSize;
265 assert(elementTypes.empty());
266 llvm::Type *i8p = CGM.getTypes().ConvertType(C.VoidPtrTy);
267 llvm::Type *intTy = CGM.getTypes().ConvertType(C.IntTy);
268 elementTypes.push_back(i8p);
269 elementTypes.push_back(intTy);
270 elementTypes.push_back(intTy);
271 elementTypes.push_back(i8p);
272 elementTypes.push_back(CGM.getBlockDescriptorType());
274 assert(elementTypes.size() == BlockHeaderSize);
277 /// Compute the layout of the given block. Attempts to lay the block
278 /// out with minimal space requirements.
279 static void computeBlockInfo(CodeGenModule &CGM, CGBlockInfo &info) {
280 ASTContext &C = CGM.getContext();
281 const BlockDecl *block = info.getBlockDecl();
283 llvm::SmallVector<llvm::Type*, 8> elementTypes;
284 initializeForBlockHeader(CGM, info, elementTypes);
286 if (!block->hasCaptures()) {
288 llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true);
289 info.CanBeGlobal = true;
293 // Collect the layout chunks.
294 llvm::SmallVector<BlockLayoutChunk, 16> layout;
295 layout.reserve(block->capturesCXXThis() +
296 (block->capture_end() - block->capture_begin()));
298 CharUnits maxFieldAlign;
301 if (block->capturesCXXThis()) {
302 const DeclContext *DC = block->getDeclContext();
303 for (; isa<BlockDecl>(DC); DC = cast<BlockDecl>(DC)->getDeclContext())
306 if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(DC))
307 thisType = C.getPointerType(C.getRecordType(RD));
309 thisType = cast<CXXMethodDecl>(DC)->getThisType(C);
311 llvm::Type *llvmType = CGM.getTypes().ConvertType(thisType);
312 std::pair<CharUnits,CharUnits> tinfo
313 = CGM.getContext().getTypeInfoInChars(thisType);
314 maxFieldAlign = std::max(maxFieldAlign, tinfo.second);
316 layout.push_back(BlockLayoutChunk(tinfo.second, tinfo.first, 0, llvmType));
319 // Next, all the block captures.
320 for (BlockDecl::capture_const_iterator ci = block->capture_begin(),
321 ce = block->capture_end(); ci != ce; ++ci) {
322 const VarDecl *variable = ci->getVariable();
325 // We have to copy/dispose of the __block reference.
326 info.NeedsCopyDispose = true;
328 // Just use void* instead of a pointer to the byref type.
329 QualType byRefPtrTy = C.VoidPtrTy;
331 llvm::Type *llvmType = CGM.getTypes().ConvertType(byRefPtrTy);
332 std::pair<CharUnits,CharUnits> tinfo
333 = CGM.getContext().getTypeInfoInChars(byRefPtrTy);
334 maxFieldAlign = std::max(maxFieldAlign, tinfo.second);
336 layout.push_back(BlockLayoutChunk(tinfo.second, tinfo.first,
341 // Otherwise, build a layout chunk with the size and alignment of
343 if (llvm::Constant *constant = tryCaptureAsConstant(CGM, variable)) {
344 info.Captures[variable] = CGBlockInfo::Capture::makeConstant(constant);
348 // If we have a lifetime qualifier, honor it for capture purposes.
349 // That includes *not* copying it if it's __unsafe_unretained.
350 if (Qualifiers::ObjCLifetime lifetime
351 = variable->getType().getObjCLifetime()) {
353 case Qualifiers::OCL_None: llvm_unreachable("impossible");
354 case Qualifiers::OCL_ExplicitNone:
355 case Qualifiers::OCL_Autoreleasing:
358 case Qualifiers::OCL_Strong:
359 case Qualifiers::OCL_Weak:
360 info.NeedsCopyDispose = true;
363 // Block pointers require copy/dispose. So do Objective-C pointers.
364 } else if (variable->getType()->isObjCRetainableType()) {
365 info.NeedsCopyDispose = true;
367 // So do types that require non-trivial copy construction.
368 } else if (ci->hasCopyExpr()) {
369 info.NeedsCopyDispose = true;
370 info.HasCXXObject = true;
372 // And so do types with destructors.
373 } else if (CGM.getLangOptions().CPlusPlus) {
374 if (const CXXRecordDecl *record =
375 variable->getType()->getAsCXXRecordDecl()) {
376 if (!record->hasTrivialDestructor()) {
377 info.HasCXXObject = true;
378 info.NeedsCopyDispose = true;
383 CharUnits size = C.getTypeSizeInChars(variable->getType());
384 CharUnits align = C.getDeclAlign(variable);
385 maxFieldAlign = std::max(maxFieldAlign, align);
387 llvm::Type *llvmType =
388 CGM.getTypes().ConvertTypeForMem(variable->getType());
390 layout.push_back(BlockLayoutChunk(align, size, &*ci, llvmType));
393 // If that was everything, we're done here.
394 if (layout.empty()) {
396 llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true);
397 info.CanBeGlobal = true;
401 // Sort the layout by alignment. We have to use a stable sort here
402 // to get reproducible results. There should probably be an
403 // llvm::array_pod_stable_sort.
404 std::stable_sort(layout.begin(), layout.end());
406 CharUnits &blockSize = info.BlockSize;
407 info.BlockAlign = std::max(maxFieldAlign, info.BlockAlign);
409 // Assuming that the first byte in the header is maximally aligned,
410 // get the alignment of the first byte following the header.
411 CharUnits endAlign = getLowBit(blockSize);
413 // If the end of the header isn't satisfactorily aligned for the
414 // maximum thing, look for things that are okay with the header-end
415 // alignment, and keep appending them until we get something that's
416 // aligned right. This algorithm is only guaranteed optimal if
417 // that condition is satisfied at some point; otherwise we can get
419 // header // next byte has alignment 4
420 // something_with_size_5; // next byte has alignment 1
421 // something_with_alignment_8;
422 // which has 7 bytes of padding, as opposed to the naive solution
423 // which might have less (?).
424 if (endAlign < maxFieldAlign) {
425 llvm::SmallVectorImpl<BlockLayoutChunk>::iterator
426 li = layout.begin() + 1, le = layout.end();
428 // Look for something that the header end is already
429 // satisfactorily aligned for.
430 for (; li != le && endAlign < li->Alignment; ++li)
433 // If we found something that's naturally aligned for the end of
434 // the header, keep adding things...
436 llvm::SmallVectorImpl<BlockLayoutChunk>::iterator first = li;
437 for (; li != le; ++li) {
438 assert(endAlign >= li->Alignment);
440 li->setIndex(info, elementTypes.size());
441 elementTypes.push_back(li->Type);
442 blockSize += li->Size;
443 endAlign = getLowBit(blockSize);
445 // ...until we get to the alignment of the maximum field.
446 if (endAlign >= maxFieldAlign)
450 // Don't re-append everything we just appended.
451 layout.erase(first, li);
455 // At this point, we just have to add padding if the end align still
456 // isn't aligned right.
457 if (endAlign < maxFieldAlign) {
458 CharUnits padding = maxFieldAlign - endAlign;
460 elementTypes.push_back(llvm::ArrayType::get(CGM.Int8Ty,
461 padding.getQuantity()));
462 blockSize += padding;
464 endAlign = getLowBit(blockSize);
465 assert(endAlign >= maxFieldAlign);
468 // Slam everything else on now. This works because they have
469 // strictly decreasing alignment and we expect that size is always a
470 // multiple of alignment.
471 for (llvm::SmallVectorImpl<BlockLayoutChunk>::iterator
472 li = layout.begin(), le = layout.end(); li != le; ++li) {
473 assert(endAlign >= li->Alignment);
474 li->setIndex(info, elementTypes.size());
475 elementTypes.push_back(li->Type);
476 blockSize += li->Size;
477 endAlign = getLowBit(blockSize);
481 llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true);
484 /// Emit a block literal expression in the current function.
485 llvm::Value *CodeGenFunction::EmitBlockLiteral(const BlockExpr *blockExpr) {
486 std::string Name = CurFn->getName();
487 CGBlockInfo blockInfo(blockExpr, Name.c_str());
489 // Compute information about the layout, etc., of this block.
490 computeBlockInfo(CGM, blockInfo);
492 // Using that metadata, generate the actual block function.
493 llvm::Constant *blockFn
494 = CodeGenFunction(CGM).GenerateBlockFunction(CurGD, blockInfo,
495 CurFuncDecl, LocalDeclMap);
496 blockFn = llvm::ConstantExpr::getBitCast(blockFn, VoidPtrTy);
498 // If there is nothing to capture, we can emit this as a global block.
499 if (blockInfo.CanBeGlobal)
500 return buildGlobalBlock(CGM, blockInfo, blockFn);
502 // Otherwise, we have to emit this as a local block.
504 llvm::Constant *isa = CGM.getNSConcreteStackBlock();
505 isa = llvm::ConstantExpr::getBitCast(isa, VoidPtrTy);
507 // Build the block descriptor.
508 llvm::Constant *descriptor = buildBlockDescriptor(CGM, blockInfo);
510 const llvm::Type *intTy = ConvertType(getContext().IntTy);
512 llvm::AllocaInst *blockAddr =
513 CreateTempAlloca(blockInfo.StructureType, "block");
514 blockAddr->setAlignment(blockInfo.BlockAlign.getQuantity());
516 // Compute the initial on-stack block flags.
517 BlockFlags flags = BLOCK_HAS_SIGNATURE;
518 if (blockInfo.NeedsCopyDispose) flags |= BLOCK_HAS_COPY_DISPOSE;
519 if (blockInfo.HasCXXObject) flags |= BLOCK_HAS_CXX_OBJ;
520 if (blockInfo.UsesStret) flags |= BLOCK_USE_STRET;
522 // Initialize the block literal.
523 Builder.CreateStore(isa, Builder.CreateStructGEP(blockAddr, 0, "block.isa"));
524 Builder.CreateStore(llvm::ConstantInt::get(intTy, flags.getBitMask()),
525 Builder.CreateStructGEP(blockAddr, 1, "block.flags"));
526 Builder.CreateStore(llvm::ConstantInt::get(intTy, 0),
527 Builder.CreateStructGEP(blockAddr, 2, "block.reserved"));
528 Builder.CreateStore(blockFn, Builder.CreateStructGEP(blockAddr, 3,
530 Builder.CreateStore(descriptor, Builder.CreateStructGEP(blockAddr, 4,
531 "block.descriptor"));
533 // Finally, capture all the values into the block.
534 const BlockDecl *blockDecl = blockInfo.getBlockDecl();
537 if (blockDecl->capturesCXXThis()) {
538 llvm::Value *addr = Builder.CreateStructGEP(blockAddr,
539 blockInfo.CXXThisIndex,
540 "block.captured-this.addr");
541 Builder.CreateStore(LoadCXXThis(), addr);
544 // Next, captured variables.
545 for (BlockDecl::capture_const_iterator ci = blockDecl->capture_begin(),
546 ce = blockDecl->capture_end(); ci != ce; ++ci) {
547 const VarDecl *variable = ci->getVariable();
548 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
550 // Ignore constant captures.
551 if (capture.isConstant()) continue;
553 QualType type = variable->getType();
555 // This will be a [[type]]*, except that a byref entry will just be
557 llvm::Value *blockField =
558 Builder.CreateStructGEP(blockAddr, capture.getIndex(),
561 // Compute the address of the thing we're going to move into the
564 if (ci->isNested()) {
565 // We need to use the capture from the enclosing block.
566 const CGBlockInfo::Capture &enclosingCapture =
567 BlockInfo->getCapture(variable);
569 // This is a [[type]]*, except that a byref entry wil just be an i8**.
570 src = Builder.CreateStructGEP(LoadBlockStruct(),
571 enclosingCapture.getIndex(),
572 "block.capture.addr");
574 // This is a [[type]]*.
575 src = LocalDeclMap[variable];
578 // For byrefs, we just write the pointer to the byref struct into
579 // the block field. There's no need to chase the forwarding
580 // pointer at this point, since we're building something that will
581 // live a shorter life than the stack byref anyway.
583 // Get a void* that points to the byref struct.
585 src = Builder.CreateLoad(src, "byref.capture");
587 src = Builder.CreateBitCast(src, VoidPtrTy);
589 // Write that void* into the capture field.
590 Builder.CreateStore(src, blockField);
592 // If we have a copy constructor, evaluate that into the block field.
593 } else if (const Expr *copyExpr = ci->getCopyExpr()) {
594 EmitSynthesizedCXXCopyCtor(blockField, src, copyExpr);
596 // If it's a reference variable, copy the reference into the block field.
597 } else if (type->isReferenceType()) {
598 Builder.CreateStore(Builder.CreateLoad(src, "ref.val"), blockField);
600 // Otherwise, fake up a POD copy into the block field.
602 // Fake up a new variable so that EmitScalarInit doesn't think
603 // we're referring to the variable in its own initializer.
604 ImplicitParamDecl blockFieldPseudoVar(/*DC*/ 0, SourceLocation(),
607 // We use one of these or the other depending on whether the
608 // reference is nested.
609 DeclRefExpr notNested(const_cast<VarDecl*>(variable), type, VK_LValue,
611 BlockDeclRefExpr nested(const_cast<VarDecl*>(variable), type,
612 VK_LValue, SourceLocation(), /*byref*/ false);
615 (ci->isNested() ? static_cast<Expr*>(&nested) : ¬Nested);
617 ImplicitCastExpr l2r(ImplicitCastExpr::OnStack, type, CK_LValueToRValue,
619 EmitExprAsInit(&l2r, &blockFieldPseudoVar,
620 LValue::MakeAddr(blockField, type,
621 getContext().getDeclAlign(variable)
624 /*captured by init*/ false);
627 // Push a destructor if necessary. The semantics for when this
628 // actually gets run are really obscure.
629 if (!ci->isByRef()) {
630 switch (QualType::DestructionKind dtorKind = type.isDestructedType()) {
631 case QualType::DK_none:
634 // Block captures count as local values and have imprecise semantics.
635 // They also can't be arrays, so need to worry about that.
636 case QualType::DK_objc_strong_lifetime: {
637 // This local is a GCC and MSVC compiler workaround.
638 Destroyer *destroyer = &destroyARCStrongImprecise;
639 pushDestroy(getCleanupKind(dtorKind), blockField, type,
640 *destroyer, /*useEHCleanupForArray*/ false);
644 case QualType::DK_objc_weak_lifetime:
645 case QualType::DK_cxx_destructor:
646 pushDestroy(dtorKind, blockField, type);
652 // Cast to the converted block-pointer type, which happens (somewhat
653 // unfortunately) to be a pointer to function type.
654 llvm::Value *result =
655 Builder.CreateBitCast(blockAddr,
656 ConvertType(blockInfo.getBlockExpr()->getType()));
662 llvm::Type *CodeGenModule::getBlockDescriptorType() {
663 if (BlockDescriptorType)
664 return BlockDescriptorType;
666 llvm::Type *UnsignedLongTy =
667 getTypes().ConvertType(getContext().UnsignedLongTy);
669 // struct __block_descriptor {
670 // unsigned long reserved;
671 // unsigned long block_size;
673 // // later, the following will be added
676 // void (*copyHelper)();
677 // void (*copyHelper)();
678 // } helpers; // !!! optional
680 // const char *signature; // the block signature
681 // const char *layout; // reserved
683 BlockDescriptorType =
684 llvm::StructType::createNamed("struct.__block_descriptor",
685 UnsignedLongTy, UnsignedLongTy, NULL);
687 // Now form a pointer to that.
688 BlockDescriptorType = llvm::PointerType::getUnqual(BlockDescriptorType);
689 return BlockDescriptorType;
692 llvm::Type *CodeGenModule::getGenericBlockLiteralType() {
693 if (GenericBlockLiteralType)
694 return GenericBlockLiteralType;
696 llvm::Type *BlockDescPtrTy = getBlockDescriptorType();
698 // struct __block_literal_generic {
702 // void (*__invoke)(void *);
703 // struct __block_descriptor *__descriptor;
705 GenericBlockLiteralType =
706 llvm::StructType::createNamed("struct.__block_literal_generic",
714 return GenericBlockLiteralType;
718 RValue CodeGenFunction::EmitBlockCallExpr(const CallExpr* E,
719 ReturnValueSlot ReturnValue) {
720 const BlockPointerType *BPT =
721 E->getCallee()->getType()->getAs<BlockPointerType>();
723 llvm::Value *Callee = EmitScalarExpr(E->getCallee());
725 // Get a pointer to the generic block literal.
726 const llvm::Type *BlockLiteralTy =
727 llvm::PointerType::getUnqual(CGM.getGenericBlockLiteralType());
729 // Bitcast the callee to a block literal.
730 llvm::Value *BlockLiteral =
731 Builder.CreateBitCast(Callee, BlockLiteralTy, "block.literal");
733 // Get the function pointer from the literal.
734 llvm::Value *FuncPtr = Builder.CreateStructGEP(BlockLiteral, 3, "tmp");
736 BlockLiteral = Builder.CreateBitCast(BlockLiteral, VoidPtrTy, "tmp");
738 // Add the block literal.
740 Args.add(RValue::get(BlockLiteral), getContext().VoidPtrTy);
742 QualType FnType = BPT->getPointeeType();
744 // And the rest of the arguments.
745 EmitCallArgs(Args, FnType->getAs<FunctionProtoType>(),
746 E->arg_begin(), E->arg_end());
748 // Load the function.
749 llvm::Value *Func = Builder.CreateLoad(FuncPtr, "tmp");
751 const FunctionType *FuncTy = FnType->castAs<FunctionType>();
752 QualType ResultType = FuncTy->getResultType();
754 const CGFunctionInfo &FnInfo =
755 CGM.getTypes().getFunctionInfo(ResultType, Args,
756 FuncTy->getExtInfo());
758 // Cast the function pointer to the right type.
759 const llvm::Type *BlockFTy =
760 CGM.getTypes().GetFunctionType(FnInfo, false);
762 const llvm::Type *BlockFTyPtr = llvm::PointerType::getUnqual(BlockFTy);
763 Func = Builder.CreateBitCast(Func, BlockFTyPtr);
765 // And call the block.
766 return EmitCall(FnInfo, Func, ReturnValue, Args);
769 llvm::Value *CodeGenFunction::GetAddrOfBlockDecl(const VarDecl *variable,
771 assert(BlockInfo && "evaluating block ref without block information?");
772 const CGBlockInfo::Capture &capture = BlockInfo->getCapture(variable);
774 // Handle constant captures.
775 if (capture.isConstant()) return LocalDeclMap[variable];
778 Builder.CreateStructGEP(LoadBlockStruct(), capture.getIndex(),
779 "block.capture.addr");
782 // addr should be a void** right now. Load, then cast the result
785 addr = Builder.CreateLoad(addr);
786 const llvm::PointerType *byrefPointerType
787 = llvm::PointerType::get(BuildByRefType(variable), 0);
788 addr = Builder.CreateBitCast(addr, byrefPointerType,
791 // Follow the forwarding pointer.
792 addr = Builder.CreateStructGEP(addr, 1, "byref.forwarding");
793 addr = Builder.CreateLoad(addr, "byref.addr.forwarded");
795 // Cast back to byref* and GEP over to the actual object.
796 addr = Builder.CreateBitCast(addr, byrefPointerType);
797 addr = Builder.CreateStructGEP(addr, getByRefValueLLVMField(variable),
798 variable->getNameAsString());
801 if (variable->getType()->isReferenceType())
802 addr = Builder.CreateLoad(addr, "ref.tmp");
808 CodeGenModule::GetAddrOfGlobalBlock(const BlockExpr *blockExpr,
810 CGBlockInfo blockInfo(blockExpr, name);
812 // Compute information about the layout, etc., of this block.
813 computeBlockInfo(*this, blockInfo);
815 // Using that metadata, generate the actual block function.
816 llvm::Constant *blockFn;
818 llvm::DenseMap<const Decl*, llvm::Value*> LocalDeclMap;
819 blockFn = CodeGenFunction(*this).GenerateBlockFunction(GlobalDecl(),
823 blockFn = llvm::ConstantExpr::getBitCast(blockFn, VoidPtrTy);
825 return buildGlobalBlock(*this, blockInfo, blockFn);
828 static llvm::Constant *buildGlobalBlock(CodeGenModule &CGM,
829 const CGBlockInfo &blockInfo,
830 llvm::Constant *blockFn) {
831 assert(blockInfo.CanBeGlobal);
833 // Generate the constants for the block literal initializer.
834 llvm::Constant *fields[BlockHeaderSize];
837 fields[0] = CGM.getNSConcreteGlobalBlock();
840 BlockFlags flags = BLOCK_IS_GLOBAL | BLOCK_HAS_SIGNATURE;
841 if (blockInfo.UsesStret) flags |= BLOCK_USE_STRET;
843 fields[1] = llvm::ConstantInt::get(CGM.IntTy, flags.getBitMask());
846 fields[2] = llvm::Constant::getNullValue(CGM.IntTy);
852 fields[4] = buildBlockDescriptor(CGM, blockInfo);
854 llvm::Constant *init = llvm::ConstantStruct::getAnon(fields);
856 llvm::GlobalVariable *literal =
857 new llvm::GlobalVariable(CGM.getModule(),
860 llvm::GlobalVariable::InternalLinkage,
862 "__block_literal_global");
863 literal->setAlignment(blockInfo.BlockAlign.getQuantity());
865 // Return a constant of the appropriately-casted type.
866 const llvm::Type *requiredType =
867 CGM.getTypes().ConvertType(blockInfo.getBlockExpr()->getType());
868 return llvm::ConstantExpr::getBitCast(literal, requiredType);
872 CodeGenFunction::GenerateBlockFunction(GlobalDecl GD,
873 const CGBlockInfo &blockInfo,
874 const Decl *outerFnDecl,
875 const DeclMapTy &ldm) {
876 const BlockDecl *blockDecl = blockInfo.getBlockDecl();
878 // Check if we should generate debug info for this block function.
879 if (CGM.getModuleDebugInfo())
880 DebugInfo = CGM.getModuleDebugInfo();
882 BlockInfo = &blockInfo;
884 // Arrange for local static and local extern declarations to appear
885 // to be local to this function as well, in case they're directly
886 // referenced in a block.
887 for (DeclMapTy::const_iterator i = ldm.begin(), e = ldm.end(); i != e; ++i) {
888 const VarDecl *var = dyn_cast<VarDecl>(i->first);
889 if (var && !var->hasLocalStorage())
890 LocalDeclMap[var] = i->second;
893 // Begin building the function declaration.
895 // Build the argument list.
896 FunctionArgList args;
898 // The first argument is the block pointer. Just take it as a void*
899 // and cast it later.
900 QualType selfTy = getContext().VoidPtrTy;
901 IdentifierInfo *II = &CGM.getContext().Idents.get(".block_descriptor");
903 ImplicitParamDecl selfDecl(const_cast<BlockDecl*>(blockDecl),
904 SourceLocation(), II, selfTy);
905 args.push_back(&selfDecl);
907 // Now add the rest of the parameters.
908 for (BlockDecl::param_const_iterator i = blockDecl->param_begin(),
909 e = blockDecl->param_end(); i != e; ++i)
912 // Create the function declaration.
913 const FunctionProtoType *fnType =
914 cast<FunctionProtoType>(blockInfo.getBlockExpr()->getFunctionType());
915 const CGFunctionInfo &fnInfo =
916 CGM.getTypes().getFunctionInfo(fnType->getResultType(), args,
917 fnType->getExtInfo());
918 if (CGM.ReturnTypeUsesSRet(fnInfo))
919 blockInfo.UsesStret = true;
921 const llvm::FunctionType *fnLLVMType =
922 CGM.getTypes().GetFunctionType(fnInfo, fnType->isVariadic());
925 CGM.getBlockMangledName(GD, name, blockDecl);
927 llvm::Function::Create(fnLLVMType, llvm::GlobalValue::InternalLinkage,
928 name.getString(), &CGM.getModule());
929 CGM.SetInternalFunctionAttributes(blockDecl, fn, fnInfo);
931 // Begin generating the function.
932 StartFunction(blockDecl, fnType->getResultType(), fn, fnInfo, args,
933 blockInfo.getBlockExpr()->getBody()->getLocStart());
934 CurFuncDecl = outerFnDecl; // StartFunction sets this to blockDecl
936 // Okay. Undo some of what StartFunction did.
938 // Pull the 'self' reference out of the local decl map.
939 llvm::Value *blockAddr = LocalDeclMap[&selfDecl];
940 LocalDeclMap.erase(&selfDecl);
941 BlockPointer = Builder.CreateBitCast(blockAddr,
942 blockInfo.StructureType->getPointerTo(),
945 // If we have a C++ 'this' reference, go ahead and force it into
947 if (blockDecl->capturesCXXThis()) {
948 llvm::Value *addr = Builder.CreateStructGEP(BlockPointer,
949 blockInfo.CXXThisIndex,
950 "block.captured-this");
951 CXXThisValue = Builder.CreateLoad(addr, "this");
954 // LoadObjCSelf() expects there to be an entry for 'self' in LocalDeclMap;
956 if (const ObjCMethodDecl *method
957 = dyn_cast_or_null<ObjCMethodDecl>(CurFuncDecl)) {
958 const VarDecl *self = method->getSelfDecl();
960 // There might not be a capture for 'self', but if there is...
961 if (blockInfo.Captures.count(self)) {
962 const CGBlockInfo::Capture &capture = blockInfo.getCapture(self);
963 llvm::Value *selfAddr = Builder.CreateStructGEP(BlockPointer,
965 "block.captured-self");
966 LocalDeclMap[self] = selfAddr;
970 // Also force all the constant captures.
971 for (BlockDecl::capture_const_iterator ci = blockDecl->capture_begin(),
972 ce = blockDecl->capture_end(); ci != ce; ++ci) {
973 const VarDecl *variable = ci->getVariable();
974 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
975 if (!capture.isConstant()) continue;
977 unsigned align = getContext().getDeclAlign(variable).getQuantity();
979 llvm::AllocaInst *alloca =
980 CreateMemTemp(variable->getType(), "block.captured-const");
981 alloca->setAlignment(align);
983 Builder.CreateStore(capture.getConstant(), alloca, align);
985 LocalDeclMap[variable] = alloca;
988 // Save a spot to insert the debug information for all the BlockDeclRefDecls.
989 llvm::BasicBlock *entry = Builder.GetInsertBlock();
990 llvm::BasicBlock::iterator entry_ptr = Builder.GetInsertPoint();
993 EmitStmt(blockDecl->getBody());
995 // Remember where we were...
996 llvm::BasicBlock *resume = Builder.GetInsertBlock();
998 // Go back to the entry.
1000 Builder.SetInsertPoint(entry, entry_ptr);
1002 // Emit debug information for all the BlockDeclRefDecls.
1003 // FIXME: also for 'this'
1004 if (CGDebugInfo *DI = getDebugInfo()) {
1005 for (BlockDecl::capture_const_iterator ci = blockDecl->capture_begin(),
1006 ce = blockDecl->capture_end(); ci != ce; ++ci) {
1007 const VarDecl *variable = ci->getVariable();
1008 DI->setLocation(variable->getLocation());
1010 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
1011 if (capture.isConstant()) {
1012 DI->EmitDeclareOfAutoVariable(variable, LocalDeclMap[variable],
1017 DI->EmitDeclareOfBlockDeclRefVariable(variable, BlockPointer,
1018 Builder, blockInfo);
1022 // And resume where we left off.
1024 Builder.ClearInsertionPoint();
1026 Builder.SetInsertPoint(resume);
1028 FinishFunction(cast<CompoundStmt>(blockDecl->getBody())->getRBracLoc());
1034 notes.push_back(HelperInfo());
1035 HelperInfo ¬e = notes.back();
1036 note.index = capture.getIndex();
1037 note.RequiresCopying = (ci->hasCopyExpr() || BlockRequiresCopying(type));
1038 note.cxxbar_import = ci->getCopyExpr();
1040 if (ci->isByRef()) {
1041 note.flag = BLOCK_FIELD_IS_BYREF;
1042 if (type.isObjCGCWeak())
1043 note.flag |= BLOCK_FIELD_IS_WEAK;
1044 } else if (type->isBlockPointerType()) {
1045 note.flag = BLOCK_FIELD_IS_BLOCK;
1047 note.flag = BLOCK_FIELD_IS_OBJECT;
1054 CodeGenFunction::GenerateCopyHelperFunction(const CGBlockInfo &blockInfo) {
1055 ASTContext &C = getContext();
1057 FunctionArgList args;
1058 ImplicitParamDecl dstDecl(0, SourceLocation(), 0, C.VoidPtrTy);
1059 args.push_back(&dstDecl);
1060 ImplicitParamDecl srcDecl(0, SourceLocation(), 0, C.VoidPtrTy);
1061 args.push_back(&srcDecl);
1063 const CGFunctionInfo &FI =
1064 CGM.getTypes().getFunctionInfo(C.VoidTy, args, FunctionType::ExtInfo());
1066 // FIXME: it would be nice if these were mergeable with things with
1067 // identical semantics.
1068 const llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI, false);
1070 llvm::Function *Fn =
1071 llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
1072 "__copy_helper_block_", &CGM.getModule());
1075 = &CGM.getContext().Idents.get("__copy_helper_block_");
1077 // Check if we should generate debug info for this block helper function.
1078 if (CGM.getModuleDebugInfo())
1079 DebugInfo = CGM.getModuleDebugInfo();
1081 FunctionDecl *FD = FunctionDecl::Create(C,
1082 C.getTranslationUnitDecl(),
1084 SourceLocation(), II, C.VoidTy, 0,
1089 StartFunction(FD, C.VoidTy, Fn, FI, args, SourceLocation());
1091 const llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo();
1093 llvm::Value *src = GetAddrOfLocalVar(&srcDecl);
1094 src = Builder.CreateLoad(src);
1095 src = Builder.CreateBitCast(src, structPtrTy, "block.source");
1097 llvm::Value *dst = GetAddrOfLocalVar(&dstDecl);
1098 dst = Builder.CreateLoad(dst);
1099 dst = Builder.CreateBitCast(dst, structPtrTy, "block.dest");
1101 const BlockDecl *blockDecl = blockInfo.getBlockDecl();
1103 for (BlockDecl::capture_const_iterator ci = blockDecl->capture_begin(),
1104 ce = blockDecl->capture_end(); ci != ce; ++ci) {
1105 const VarDecl *variable = ci->getVariable();
1106 QualType type = variable->getType();
1108 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
1109 if (capture.isConstant()) continue;
1111 const Expr *copyExpr = ci->getCopyExpr();
1112 BlockFieldFlags flags;
1114 bool isARCWeakCapture = false;
1117 assert(!ci->isByRef());
1118 // don't bother computing flags
1120 } else if (ci->isByRef()) {
1121 flags = BLOCK_FIELD_IS_BYREF;
1122 if (type.isObjCGCWeak())
1123 flags |= BLOCK_FIELD_IS_WEAK;
1125 } else if (type->isObjCRetainableType()) {
1126 flags = BLOCK_FIELD_IS_OBJECT;
1127 if (type->isBlockPointerType())
1128 flags = BLOCK_FIELD_IS_BLOCK;
1130 // Special rules for ARC captures:
1131 if (getLangOptions().ObjCAutoRefCount) {
1132 Qualifiers qs = type.getQualifiers();
1134 // Don't generate special copy logic for a captured object
1135 // unless it's __strong or __weak.
1136 if (!qs.hasStrongOrWeakObjCLifetime())
1139 // Support __weak direct captures.
1140 if (qs.getObjCLifetime() == Qualifiers::OCL_Weak)
1141 isARCWeakCapture = true;
1147 unsigned index = capture.getIndex();
1148 llvm::Value *srcField = Builder.CreateStructGEP(src, index);
1149 llvm::Value *dstField = Builder.CreateStructGEP(dst, index);
1151 // If there's an explicit copy expression, we do that.
1153 EmitSynthesizedCXXCopyCtor(dstField, srcField, copyExpr);
1154 } else if (isARCWeakCapture) {
1155 EmitARCCopyWeak(dstField, srcField);
1157 llvm::Value *srcValue = Builder.CreateLoad(srcField, "blockcopy.src");
1158 srcValue = Builder.CreateBitCast(srcValue, VoidPtrTy);
1159 llvm::Value *dstAddr = Builder.CreateBitCast(dstField, VoidPtrTy);
1160 Builder.CreateCall3(CGM.getBlockObjectAssign(), dstAddr, srcValue,
1161 llvm::ConstantInt::get(Int32Ty, flags.getBitMask()));
1167 return llvm::ConstantExpr::getBitCast(Fn, VoidPtrTy);
1171 CodeGenFunction::GenerateDestroyHelperFunction(const CGBlockInfo &blockInfo) {
1172 ASTContext &C = getContext();
1174 FunctionArgList args;
1175 ImplicitParamDecl srcDecl(0, SourceLocation(), 0, C.VoidPtrTy);
1176 args.push_back(&srcDecl);
1178 const CGFunctionInfo &FI =
1179 CGM.getTypes().getFunctionInfo(C.VoidTy, args, FunctionType::ExtInfo());
1181 // FIXME: We'd like to put these into a mergable by content, with
1182 // internal linkage.
1183 const llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI, false);
1185 llvm::Function *Fn =
1186 llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
1187 "__destroy_helper_block_", &CGM.getModule());
1189 // Check if we should generate debug info for this block destroy function.
1190 if (CGM.getModuleDebugInfo())
1191 DebugInfo = CGM.getModuleDebugInfo();
1194 = &CGM.getContext().Idents.get("__destroy_helper_block_");
1196 FunctionDecl *FD = FunctionDecl::Create(C, C.getTranslationUnitDecl(),
1198 SourceLocation(), II, C.VoidTy, 0,
1202 StartFunction(FD, C.VoidTy, Fn, FI, args, SourceLocation());
1204 const llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo();
1206 llvm::Value *src = GetAddrOfLocalVar(&srcDecl);
1207 src = Builder.CreateLoad(src);
1208 src = Builder.CreateBitCast(src, structPtrTy, "block");
1210 const BlockDecl *blockDecl = blockInfo.getBlockDecl();
1212 CodeGenFunction::RunCleanupsScope cleanups(*this);
1214 for (BlockDecl::capture_const_iterator ci = blockDecl->capture_begin(),
1215 ce = blockDecl->capture_end(); ci != ce; ++ci) {
1216 const VarDecl *variable = ci->getVariable();
1217 QualType type = variable->getType();
1219 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
1220 if (capture.isConstant()) continue;
1222 BlockFieldFlags flags;
1223 const CXXDestructorDecl *dtor = 0;
1225 bool isARCWeakCapture = false;
1227 if (ci->isByRef()) {
1228 flags = BLOCK_FIELD_IS_BYREF;
1229 if (type.isObjCGCWeak())
1230 flags |= BLOCK_FIELD_IS_WEAK;
1231 } else if (const CXXRecordDecl *record = type->getAsCXXRecordDecl()) {
1232 if (record->hasTrivialDestructor())
1234 dtor = record->getDestructor();
1235 } else if (type->isObjCRetainableType()) {
1236 flags = BLOCK_FIELD_IS_OBJECT;
1237 if (type->isBlockPointerType())
1238 flags = BLOCK_FIELD_IS_BLOCK;
1240 // Special rules for ARC captures.
1241 if (getLangOptions().ObjCAutoRefCount) {
1242 Qualifiers qs = type.getQualifiers();
1244 // Don't generate special dispose logic for a captured object
1245 // unless it's __strong or __weak.
1246 if (!qs.hasStrongOrWeakObjCLifetime())
1249 // Support __weak direct captures.
1250 if (qs.getObjCLifetime() == Qualifiers::OCL_Weak)
1251 isARCWeakCapture = true;
1257 unsigned index = capture.getIndex();
1258 llvm::Value *srcField = Builder.CreateStructGEP(src, index);
1260 // If there's an explicit copy expression, we do that.
1262 PushDestructorCleanup(dtor, srcField);
1264 // If this is a __weak capture, emit the release directly.
1265 } else if (isARCWeakCapture) {
1266 EmitARCDestroyWeak(srcField);
1268 // Otherwise we call _Block_object_dispose. It wouldn't be too
1269 // hard to just emit this as a cleanup if we wanted to make sure
1270 // that things were done in reverse.
1272 llvm::Value *value = Builder.CreateLoad(srcField);
1273 value = Builder.CreateBitCast(value, VoidPtrTy);
1274 BuildBlockRelease(value, flags);
1278 cleanups.ForceCleanup();
1282 return llvm::ConstantExpr::getBitCast(Fn, VoidPtrTy);
1287 /// Emits the copy/dispose helper functions for a __block object of id type.
1288 class ObjectByrefHelpers : public CodeGenModule::ByrefHelpers {
1289 BlockFieldFlags Flags;
1292 ObjectByrefHelpers(CharUnits alignment, BlockFieldFlags flags)
1293 : ByrefHelpers(alignment), Flags(flags) {}
1295 void emitCopy(CodeGenFunction &CGF, llvm::Value *destField,
1296 llvm::Value *srcField) {
1297 destField = CGF.Builder.CreateBitCast(destField, CGF.VoidPtrTy);
1299 srcField = CGF.Builder.CreateBitCast(srcField, CGF.VoidPtrPtrTy);
1300 llvm::Value *srcValue = CGF.Builder.CreateLoad(srcField);
1302 unsigned flags = (Flags | BLOCK_BYREF_CALLER).getBitMask();
1304 llvm::Value *flagsVal = llvm::ConstantInt::get(CGF.Int32Ty, flags);
1305 llvm::Value *fn = CGF.CGM.getBlockObjectAssign();
1306 CGF.Builder.CreateCall3(fn, destField, srcValue, flagsVal);
1309 void emitDispose(CodeGenFunction &CGF, llvm::Value *field) {
1310 field = CGF.Builder.CreateBitCast(field, CGF.Int8PtrTy->getPointerTo(0));
1311 llvm::Value *value = CGF.Builder.CreateLoad(field);
1313 CGF.BuildBlockRelease(value, Flags | BLOCK_BYREF_CALLER);
1316 void profileImpl(llvm::FoldingSetNodeID &id) const {
1317 id.AddInteger(Flags.getBitMask());
1321 /// Emits the copy/dispose helpers for an ARC __block __weak variable.
1322 class ARCWeakByrefHelpers : public CodeGenModule::ByrefHelpers {
1324 ARCWeakByrefHelpers(CharUnits alignment) : ByrefHelpers(alignment) {}
1326 void emitCopy(CodeGenFunction &CGF, llvm::Value *destField,
1327 llvm::Value *srcField) {
1328 CGF.EmitARCMoveWeak(destField, srcField);
1331 void emitDispose(CodeGenFunction &CGF, llvm::Value *field) {
1332 CGF.EmitARCDestroyWeak(field);
1335 void profileImpl(llvm::FoldingSetNodeID &id) const {
1336 // 0 is distinguishable from all pointers and byref flags
1341 /// Emits the copy/dispose helpers for an ARC __block __strong variable
1342 /// that's not of block-pointer type.
1343 class ARCStrongByrefHelpers : public CodeGenModule::ByrefHelpers {
1345 ARCStrongByrefHelpers(CharUnits alignment) : ByrefHelpers(alignment) {}
1347 void emitCopy(CodeGenFunction &CGF, llvm::Value *destField,
1348 llvm::Value *srcField) {
1349 // Do a "move" by copying the value and then zeroing out the old
1352 llvm::Value *value = CGF.Builder.CreateLoad(srcField);
1354 llvm::ConstantPointerNull::get(cast<llvm::PointerType>(value->getType()));
1355 CGF.Builder.CreateStore(value, destField);
1356 CGF.Builder.CreateStore(null, srcField);
1359 void emitDispose(CodeGenFunction &CGF, llvm::Value *field) {
1360 llvm::Value *value = CGF.Builder.CreateLoad(field);
1361 CGF.EmitARCRelease(value, /*precise*/ false);
1364 void profileImpl(llvm::FoldingSetNodeID &id) const {
1365 // 1 is distinguishable from all pointers and byref flags
1370 /// Emits the copy/dispose helpers for a __block variable with a
1371 /// nontrivial copy constructor or destructor.
1372 class CXXByrefHelpers : public CodeGenModule::ByrefHelpers {
1374 const Expr *CopyExpr;
1377 CXXByrefHelpers(CharUnits alignment, QualType type,
1378 const Expr *copyExpr)
1379 : ByrefHelpers(alignment), VarType(type), CopyExpr(copyExpr) {}
1381 bool needsCopy() const { return CopyExpr != 0; }
1382 void emitCopy(CodeGenFunction &CGF, llvm::Value *destField,
1383 llvm::Value *srcField) {
1384 if (!CopyExpr) return;
1385 CGF.EmitSynthesizedCXXCopyCtor(destField, srcField, CopyExpr);
1388 void emitDispose(CodeGenFunction &CGF, llvm::Value *field) {
1389 EHScopeStack::stable_iterator cleanupDepth = CGF.EHStack.stable_begin();
1390 CGF.PushDestructorCleanup(VarType, field);
1391 CGF.PopCleanupBlocks(cleanupDepth);
1394 void profileImpl(llvm::FoldingSetNodeID &id) const {
1395 id.AddPointer(VarType.getCanonicalType().getAsOpaquePtr());
1398 } // end anonymous namespace
1400 static llvm::Constant *
1401 generateByrefCopyHelper(CodeGenFunction &CGF,
1402 const llvm::StructType &byrefType,
1403 CodeGenModule::ByrefHelpers &byrefInfo) {
1404 ASTContext &Context = CGF.getContext();
1406 QualType R = Context.VoidTy;
1408 FunctionArgList args;
1409 ImplicitParamDecl dst(0, SourceLocation(), 0, Context.VoidPtrTy);
1410 args.push_back(&dst);
1412 ImplicitParamDecl src(0, SourceLocation(), 0, Context.VoidPtrTy);
1413 args.push_back(&src);
1415 const CGFunctionInfo &FI =
1416 CGF.CGM.getTypes().getFunctionInfo(R, args, FunctionType::ExtInfo());
1418 CodeGenTypes &Types = CGF.CGM.getTypes();
1419 const llvm::FunctionType *LTy = Types.GetFunctionType(FI, false);
1421 // FIXME: We'd like to put these into a mergable by content, with
1422 // internal linkage.
1423 llvm::Function *Fn =
1424 llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
1425 "__Block_byref_object_copy_", &CGF.CGM.getModule());
1428 = &Context.Idents.get("__Block_byref_object_copy_");
1430 FunctionDecl *FD = FunctionDecl::Create(Context,
1431 Context.getTranslationUnitDecl(),
1433 SourceLocation(), II, R, 0,
1438 CGF.StartFunction(FD, R, Fn, FI, args, SourceLocation());
1440 if (byrefInfo.needsCopy()) {
1441 const llvm::Type *byrefPtrType = byrefType.getPointerTo(0);
1444 llvm::Value *destField = CGF.GetAddrOfLocalVar(&dst);
1445 destField = CGF.Builder.CreateLoad(destField);
1446 destField = CGF.Builder.CreateBitCast(destField, byrefPtrType);
1447 destField = CGF.Builder.CreateStructGEP(destField, 6, "x");
1450 llvm::Value *srcField = CGF.GetAddrOfLocalVar(&src);
1451 srcField = CGF.Builder.CreateLoad(srcField);
1452 srcField = CGF.Builder.CreateBitCast(srcField, byrefPtrType);
1453 srcField = CGF.Builder.CreateStructGEP(srcField, 6, "x");
1455 byrefInfo.emitCopy(CGF, destField, srcField);
1458 CGF.FinishFunction();
1460 return llvm::ConstantExpr::getBitCast(Fn, CGF.Int8PtrTy);
1463 /// Build the copy helper for a __block variable.
1464 static llvm::Constant *buildByrefCopyHelper(CodeGenModule &CGM,
1465 const llvm::StructType &byrefType,
1466 CodeGenModule::ByrefHelpers &info) {
1467 CodeGenFunction CGF(CGM);
1468 return generateByrefCopyHelper(CGF, byrefType, info);
1471 /// Generate code for a __block variable's dispose helper.
1472 static llvm::Constant *
1473 generateByrefDisposeHelper(CodeGenFunction &CGF,
1474 const llvm::StructType &byrefType,
1475 CodeGenModule::ByrefHelpers &byrefInfo) {
1476 ASTContext &Context = CGF.getContext();
1477 QualType R = Context.VoidTy;
1479 FunctionArgList args;
1480 ImplicitParamDecl src(0, SourceLocation(), 0, Context.VoidPtrTy);
1481 args.push_back(&src);
1483 const CGFunctionInfo &FI =
1484 CGF.CGM.getTypes().getFunctionInfo(R, args, FunctionType::ExtInfo());
1486 CodeGenTypes &Types = CGF.CGM.getTypes();
1487 const llvm::FunctionType *LTy = Types.GetFunctionType(FI, false);
1489 // FIXME: We'd like to put these into a mergable by content, with
1490 // internal linkage.
1491 llvm::Function *Fn =
1492 llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
1493 "__Block_byref_object_dispose_",
1494 &CGF.CGM.getModule());
1497 = &Context.Idents.get("__Block_byref_object_dispose_");
1499 FunctionDecl *FD = FunctionDecl::Create(Context,
1500 Context.getTranslationUnitDecl(),
1502 SourceLocation(), II, R, 0,
1506 CGF.StartFunction(FD, R, Fn, FI, args, SourceLocation());
1508 if (byrefInfo.needsDispose()) {
1509 llvm::Value *V = CGF.GetAddrOfLocalVar(&src);
1510 V = CGF.Builder.CreateLoad(V);
1511 V = CGF.Builder.CreateBitCast(V, byrefType.getPointerTo(0));
1512 V = CGF.Builder.CreateStructGEP(V, 6, "x");
1514 byrefInfo.emitDispose(CGF, V);
1517 CGF.FinishFunction();
1519 return llvm::ConstantExpr::getBitCast(Fn, CGF.Int8PtrTy);
1522 /// Build the dispose helper for a __block variable.
1523 static llvm::Constant *buildByrefDisposeHelper(CodeGenModule &CGM,
1524 const llvm::StructType &byrefType,
1525 CodeGenModule::ByrefHelpers &info) {
1526 CodeGenFunction CGF(CGM);
1527 return generateByrefDisposeHelper(CGF, byrefType, info);
1531 template <class T> static T *buildByrefHelpers(CodeGenModule &CGM,
1532 const llvm::StructType &byrefTy,
1534 // Increase the field's alignment to be at least pointer alignment,
1535 // since the layout of the byref struct will guarantee at least that.
1536 byrefInfo.Alignment = std::max(byrefInfo.Alignment,
1537 CharUnits::fromQuantity(CGM.PointerAlignInBytes));
1539 llvm::FoldingSetNodeID id;
1540 byrefInfo.Profile(id);
1543 CodeGenModule::ByrefHelpers *node
1544 = CGM.ByrefHelpersCache.FindNodeOrInsertPos(id, insertPos);
1545 if (node) return static_cast<T*>(node);
1547 byrefInfo.CopyHelper = buildByrefCopyHelper(CGM, byrefTy, byrefInfo);
1548 byrefInfo.DisposeHelper = buildByrefDisposeHelper(CGM, byrefTy, byrefInfo);
1550 T *copy = new (CGM.getContext()) T(byrefInfo);
1551 CGM.ByrefHelpersCache.InsertNode(copy, insertPos);
1555 CodeGenModule::ByrefHelpers *
1556 CodeGenFunction::buildByrefHelpers(const llvm::StructType &byrefType,
1557 const AutoVarEmission &emission) {
1558 const VarDecl &var = *emission.Variable;
1559 QualType type = var.getType();
1561 if (const CXXRecordDecl *record = type->getAsCXXRecordDecl()) {
1562 const Expr *copyExpr = CGM.getContext().getBlockVarCopyInits(&var);
1563 if (!copyExpr && record->hasTrivialDestructor()) return 0;
1565 CXXByrefHelpers byrefInfo(emission.Alignment, type, copyExpr);
1566 return ::buildByrefHelpers(CGM, byrefType, byrefInfo);
1569 // Otherwise, if we don't have a retainable type, there's nothing to do.
1570 // that the runtime does extra copies.
1571 if (!type->isObjCRetainableType()) return 0;
1573 Qualifiers qs = type.getQualifiers();
1575 // If we have lifetime, that dominates.
1576 if (Qualifiers::ObjCLifetime lifetime = qs.getObjCLifetime()) {
1577 assert(getLangOptions().ObjCAutoRefCount);
1580 case Qualifiers::OCL_None: llvm_unreachable("impossible");
1582 // These are just bits as far as the runtime is concerned.
1583 case Qualifiers::OCL_ExplicitNone:
1584 case Qualifiers::OCL_Autoreleasing:
1587 // Tell the runtime that this is ARC __weak, called by the
1589 case Qualifiers::OCL_Weak: {
1590 ARCWeakByrefHelpers byrefInfo(emission.Alignment);
1591 return ::buildByrefHelpers(CGM, byrefType, byrefInfo);
1594 // ARC __strong __block variables need to be retained.
1595 case Qualifiers::OCL_Strong:
1596 // Block-pointers need to be _Block_copy'ed, so we let the
1597 // runtime be in charge. But we can't use the code below
1598 // because we don't want to set BYREF_CALLER, which will
1599 // just make the runtime ignore us.
1600 if (type->isBlockPointerType()) {
1601 BlockFieldFlags flags = BLOCK_FIELD_IS_BLOCK;
1602 ObjectByrefHelpers byrefInfo(emission.Alignment, flags);
1603 return ::buildByrefHelpers(CGM, byrefType, byrefInfo);
1605 // Otherwise, we transfer ownership of the retain from the stack
1608 ARCStrongByrefHelpers byrefInfo(emission.Alignment);
1609 return ::buildByrefHelpers(CGM, byrefType, byrefInfo);
1612 llvm_unreachable("fell out of lifetime switch!");
1615 BlockFieldFlags flags;
1616 if (type->isBlockPointerType()) {
1617 flags |= BLOCK_FIELD_IS_BLOCK;
1618 } else if (CGM.getContext().isObjCNSObjectType(type) ||
1619 type->isObjCObjectPointerType()) {
1620 flags |= BLOCK_FIELD_IS_OBJECT;
1625 if (type.isObjCGCWeak())
1626 flags |= BLOCK_FIELD_IS_WEAK;
1628 ObjectByrefHelpers byrefInfo(emission.Alignment, flags);
1629 return ::buildByrefHelpers(CGM, byrefType, byrefInfo);
1632 unsigned CodeGenFunction::getByRefValueLLVMField(const ValueDecl *VD) const {
1633 assert(ByRefValueInfo.count(VD) && "Did not find value!");
1635 return ByRefValueInfo.find(VD)->second.second;
1638 llvm::Value *CodeGenFunction::BuildBlockByrefAddress(llvm::Value *BaseAddr,
1640 llvm::Value *Loc = Builder.CreateStructGEP(BaseAddr, 1, "forwarding");
1641 Loc = Builder.CreateLoad(Loc);
1642 Loc = Builder.CreateStructGEP(Loc, getByRefValueLLVMField(V),
1643 V->getNameAsString());
1647 /// BuildByRefType - This routine changes a __block variable declared as T x
1652 /// void *__forwarding;
1653 /// int32_t __flags;
1655 /// void *__copy_helper; // only if needed
1656 /// void *__destroy_helper; // only if needed
1657 /// char padding[X]; // only if needed
1661 const llvm::Type *CodeGenFunction::BuildByRefType(const VarDecl *D) {
1662 std::pair<const llvm::Type *, unsigned> &Info = ByRefValueInfo[D];
1666 QualType Ty = D->getType();
1668 llvm::SmallVector<llvm::Type *, 8> types;
1670 llvm::StructType *ByRefType =
1671 llvm::StructType::createNamed(getLLVMContext(),
1672 "struct.__block_byref_" + D->getNameAsString());
1675 types.push_back(Int8PtrTy);
1677 // void *__forwarding;
1678 types.push_back(llvm::PointerType::getUnqual(ByRefType));
1681 types.push_back(Int32Ty);
1684 types.push_back(Int32Ty);
1686 bool HasCopyAndDispose = getContext().BlockRequiresCopying(Ty);
1687 if (HasCopyAndDispose) {
1688 /// void *__copy_helper;
1689 types.push_back(Int8PtrTy);
1691 /// void *__destroy_helper;
1692 types.push_back(Int8PtrTy);
1695 bool Packed = false;
1696 CharUnits Align = getContext().getDeclAlign(D);
1697 if (Align > getContext().toCharUnitsFromBits(Target.getPointerAlign(0))) {
1698 // We have to insert padding.
1700 // The struct above has 2 32-bit integers.
1701 unsigned CurrentOffsetInBytes = 4 * 2;
1703 // And either 2 or 4 pointers.
1704 CurrentOffsetInBytes += (HasCopyAndDispose ? 4 : 2) *
1705 CGM.getTargetData().getTypeAllocSize(Int8PtrTy);
1707 // Align the offset.
1708 unsigned AlignedOffsetInBytes =
1709 llvm::RoundUpToAlignment(CurrentOffsetInBytes, Align.getQuantity());
1711 unsigned NumPaddingBytes = AlignedOffsetInBytes - CurrentOffsetInBytes;
1712 if (NumPaddingBytes > 0) {
1713 llvm::Type *Ty = llvm::Type::getInt8Ty(getLLVMContext());
1714 // FIXME: We need a sema error for alignment larger than the minimum of
1715 // the maximal stack alignment and the alignment of malloc on the system.
1716 if (NumPaddingBytes > 1)
1717 Ty = llvm::ArrayType::get(Ty, NumPaddingBytes);
1719 types.push_back(Ty);
1721 // We want a packed struct.
1727 types.push_back(ConvertTypeForMem(Ty));
1729 ByRefType->setBody(types, Packed);
1731 Info.first = ByRefType;
1733 Info.second = types.size() - 1;
1738 /// Initialize the structural components of a __block variable, i.e.
1739 /// everything but the actual object.
1740 void CodeGenFunction::emitByrefStructureInit(const AutoVarEmission &emission) {
1741 // Find the address of the local.
1742 llvm::Value *addr = emission.Address;
1744 // That's an alloca of the byref structure type.
1745 const llvm::StructType *byrefType = cast<llvm::StructType>(
1746 cast<llvm::PointerType>(addr->getType())->getElementType());
1748 // Build the byref helpers if necessary. This is null if we don't need any.
1749 CodeGenModule::ByrefHelpers *helpers =
1750 buildByrefHelpers(*byrefType, emission);
1752 const VarDecl &D = *emission.Variable;
1753 QualType type = D.getType();
1757 // Initialize the 'isa', which is just 0 or 1.
1759 if (type.isObjCGCWeak())
1761 V = Builder.CreateIntToPtr(Builder.getInt32(isa), Int8PtrTy, "isa");
1762 Builder.CreateStore(V, Builder.CreateStructGEP(addr, 0, "byref.isa"));
1764 // Store the address of the variable into its own forwarding pointer.
1765 Builder.CreateStore(addr,
1766 Builder.CreateStructGEP(addr, 1, "byref.forwarding"));
1769 // c) the flags field is set to either 0 if no helper functions are
1770 // needed or BLOCK_HAS_COPY_DISPOSE if they are,
1772 if (helpers) flags |= BLOCK_HAS_COPY_DISPOSE;
1773 Builder.CreateStore(llvm::ConstantInt::get(IntTy, flags.getBitMask()),
1774 Builder.CreateStructGEP(addr, 2, "byref.flags"));
1776 CharUnits byrefSize = CGM.GetTargetTypeStoreSize(byrefType);
1777 V = llvm::ConstantInt::get(IntTy, byrefSize.getQuantity());
1778 Builder.CreateStore(V, Builder.CreateStructGEP(addr, 3, "byref.size"));
1781 llvm::Value *copy_helper = Builder.CreateStructGEP(addr, 4);
1782 Builder.CreateStore(helpers->CopyHelper, copy_helper);
1784 llvm::Value *destroy_helper = Builder.CreateStructGEP(addr, 5);
1785 Builder.CreateStore(helpers->DisposeHelper, destroy_helper);
1789 void CodeGenFunction::BuildBlockRelease(llvm::Value *V, BlockFieldFlags flags) {
1790 llvm::Value *F = CGM.getBlockObjectDispose();
1792 V = Builder.CreateBitCast(V, Int8PtrTy);
1793 N = llvm::ConstantInt::get(Int32Ty, flags.getBitMask());
1794 Builder.CreateCall2(F, V, N);
1798 struct CallBlockRelease : EHScopeStack::Cleanup {
1800 CallBlockRelease(llvm::Value *Addr) : Addr(Addr) {}
1802 void Emit(CodeGenFunction &CGF, Flags flags) {
1803 // Should we be passing FIELD_IS_WEAK here?
1804 CGF.BuildBlockRelease(Addr, BLOCK_FIELD_IS_BYREF);
1809 /// Enter a cleanup to destroy a __block variable. Note that this
1810 /// cleanup should be a no-op if the variable hasn't left the stack
1811 /// yet; if a cleanup is required for the variable itself, that needs
1812 /// to be done externally.
1813 void CodeGenFunction::enterByrefCleanup(const AutoVarEmission &emission) {
1814 // We don't enter this cleanup if we're in pure-GC mode.
1815 if (CGM.getLangOptions().getGCMode() == LangOptions::GCOnly)
1818 EHStack.pushCleanup<CallBlockRelease>(NormalAndEHCleanup, emission.Address);