1//===--- CGBlocks.cpp - Emit LLVM Code for declarations -------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This contains code to emit blocks.
11//
12//===----------------------------------------------------------------------===//
13
14#include "CGDebugInfo.h"
15#include "CodeGenFunction.h"
16#include "CGObjCRuntime.h"
17#include "CodeGenModule.h"
18#include "CGBlocks.h"
19#include "clang/AST/DeclObjC.h"
20#include "llvm/Module.h"
21#include "llvm/ADT/SmallSet.h"
22#include "llvm/Target/TargetData.h"
23#include <algorithm>
24
25using namespace clang;
26using namespace CodeGen;
27
28CGBlockInfo::CGBlockInfo(const BlockDecl *block, StringRef name)
29  : Name(name), CXXThisIndex(0), CanBeGlobal(false), NeedsCopyDispose(false),
30    HasCXXObject(false), UsesStret(false), StructureType(0), Block(block),
31    DominatingIP(0) {
32
33  // Skip asm prefix, if any.  'name' is usually taken directly from
34  // the mangled name of the enclosing function.
35  if (!name.empty() && name[0] == '\01')
36    name = name.substr(1);
37}
38
39// Anchor the vtable to this translation unit.
40CodeGenModule::ByrefHelpers::~ByrefHelpers() {}
41
42/// Build the given block as a global block.
43static llvm::Constant *buildGlobalBlock(CodeGenModule &CGM,
44                                        const CGBlockInfo &blockInfo,
45                                        llvm::Constant *blockFn);
46
47/// Build the helper function to copy a block.
48static llvm::Constant *buildCopyHelper(CodeGenModule &CGM,
49                                       const CGBlockInfo &blockInfo) {
50  return CodeGenFunction(CGM).GenerateCopyHelperFunction(blockInfo);
51}
52
53/// Build the helper function to dipose of a block.
54static llvm::Constant *buildDisposeHelper(CodeGenModule &CGM,
55                                          const CGBlockInfo &blockInfo) {
56  return CodeGenFunction(CGM).GenerateDestroyHelperFunction(blockInfo);
57}
58
59/// Build the block descriptor constant for a block.
60static llvm::Constant *buildBlockDescriptor(CodeGenModule &CGM,
61                                            const CGBlockInfo &blockInfo) {
62  ASTContext &C = CGM.getContext();
63
64  llvm::Type *ulong = CGM.getTypes().ConvertType(C.UnsignedLongTy);
65  llvm::Type *i8p = CGM.getTypes().ConvertType(C.VoidPtrTy);
66
67  SmallVector<llvm::Constant*, 6> elements;
68
69  // reserved
70  elements.push_back(llvm::ConstantInt::get(ulong, 0));
71
72  // Size
73  // FIXME: What is the right way to say this doesn't fit?  We should give
74  // a user diagnostic in that case.  Better fix would be to change the
75  // API to size_t.
76  elements.push_back(llvm::ConstantInt::get(ulong,
77                                            blockInfo.BlockSize.getQuantity()));
78
79  // Optional copy/dispose helpers.
80  if (blockInfo.NeedsCopyDispose) {
81    // copy_func_helper_decl
82    elements.push_back(buildCopyHelper(CGM, blockInfo));
83
84    // destroy_func_decl
85    elements.push_back(buildDisposeHelper(CGM, blockInfo));
86  }
87
88  // Signature.  Mandatory ObjC-style method descriptor @encode sequence.
89  std::string typeAtEncoding =
90    CGM.getContext().getObjCEncodingForBlock(blockInfo.getBlockExpr());
91  elements.push_back(llvm::ConstantExpr::getBitCast(
92                          CGM.GetAddrOfConstantCString(typeAtEncoding), i8p));
93
94  // GC layout.
95  if (C.getLangOpts().ObjC1)
96    elements.push_back(CGM.getObjCRuntime().BuildGCBlockLayout(CGM, blockInfo));
97  else
98    elements.push_back(llvm::Constant::getNullValue(i8p));
99
100  llvm::Constant *init = llvm::ConstantStruct::getAnon(elements);
101
102  llvm::GlobalVariable *global =
103    new llvm::GlobalVariable(CGM.getModule(), init->getType(), true,
104                             llvm::GlobalValue::InternalLinkage,
105                             init, "__block_descriptor_tmp");
106
107  return llvm::ConstantExpr::getBitCast(global, CGM.getBlockDescriptorType());
108}
109
110/*
111  Purely notional variadic template describing the layout of a block.
112
113  template <class _ResultType, class... _ParamTypes, class... _CaptureTypes>
114  struct Block_literal {
115    /// Initialized to one of:
116    ///   extern void *_NSConcreteStackBlock[];
117    ///   extern void *_NSConcreteGlobalBlock[];
118    ///
119    /// In theory, we could start one off malloc'ed by setting
120    /// BLOCK_NEEDS_FREE, giving it a refcount of 1, and using
121    /// this isa:
122    ///   extern void *_NSConcreteMallocBlock[];
123    struct objc_class *isa;
124
125    /// These are the flags (with corresponding bit number) that the
126    /// compiler is actually supposed to know about.
127    ///  25. BLOCK_HAS_COPY_DISPOSE - indicates that the block
128    ///   descriptor provides copy and dispose helper functions
129    ///  26. BLOCK_HAS_CXX_OBJ - indicates that there's a captured
130    ///   object with a nontrivial destructor or copy constructor
131    ///  28. BLOCK_IS_GLOBAL - indicates that the block is allocated
132    ///   as global memory
133    ///  29. BLOCK_USE_STRET - indicates that the block function
134    ///   uses stret, which objc_msgSend needs to know about
135    ///  30. BLOCK_HAS_SIGNATURE - indicates that the block has an
136    ///   @encoded signature string
137    /// And we're not supposed to manipulate these:
138    ///  24. BLOCK_NEEDS_FREE - indicates that the block has been moved
139    ///   to malloc'ed memory
140    ///  27. BLOCK_IS_GC - indicates that the block has been moved to
141    ///   to GC-allocated memory
142    /// Additionally, the bottom 16 bits are a reference count which
143    /// should be zero on the stack.
144    int flags;
145
146    /// Reserved;  should be zero-initialized.
147    int reserved;
148
149    /// Function pointer generated from block literal.
150    _ResultType (*invoke)(Block_literal *, _ParamTypes...);
151
152    /// Block description metadata generated from block literal.
153    struct Block_descriptor *block_descriptor;
154
155    /// Captured values follow.
156    _CapturesTypes captures...;
157  };
158 */
159
160/// The number of fields in a block header.
161const unsigned BlockHeaderSize = 5;
162
163namespace {
164  /// A chunk of data that we actually have to capture in the block.
165  struct BlockLayoutChunk {
166    CharUnits Alignment;
167    CharUnits Size;
168    const BlockDecl::Capture *Capture; // null for 'this'
169    llvm::Type *Type;
170
171    BlockLayoutChunk(CharUnits align, CharUnits size,
172                     const BlockDecl::Capture *capture,
173                     llvm::Type *type)
174      : Alignment(align), Size(size), Capture(capture), Type(type) {}
175
176    /// Tell the block info that this chunk has the given field index.
177    void setIndex(CGBlockInfo &info, unsigned index) {
178      if (!Capture)
179        info.CXXThisIndex = index;
180      else
181        info.Captures[Capture->getVariable()]
182          = CGBlockInfo::Capture::makeIndex(index);
183    }
184  };
185
186  /// Order by descending alignment.
187  bool operator<(const BlockLayoutChunk &left, const BlockLayoutChunk &right) {
188    return left.Alignment > right.Alignment;
189  }
190}
191
192/// Determines if the given type is safe for constant capture in C++.
193static bool isSafeForCXXConstantCapture(QualType type) {
194  const RecordType *recordType =
195    type->getBaseElementTypeUnsafe()->getAs<RecordType>();
196
197  // Only records can be unsafe.
198  if (!recordType) return true;
199
200  const CXXRecordDecl *record = cast<CXXRecordDecl>(recordType->getDecl());
201
202  // Maintain semantics for classes with non-trivial dtors or copy ctors.
203  if (!record->hasTrivialDestructor()) return false;
204  if (!record->hasTrivialCopyConstructor()) return false;
205
206  // Otherwise, we just have to make sure there aren't any mutable
207  // fields that might have changed since initialization.
208  return !record->hasMutableFields();
209}
210
211/// It is illegal to modify a const object after initialization.
212/// Therefore, if a const object has a constant initializer, we don't
213/// actually need to keep storage for it in the block; we'll just
214/// rematerialize it at the start of the block function.  This is
215/// acceptable because we make no promises about address stability of
216/// captured variables.
217static llvm::Constant *tryCaptureAsConstant(CodeGenModule &CGM,
218                                            CodeGenFunction *CGF,
219                                            const VarDecl *var) {
220  QualType type = var->getType();
221
222  // We can only do this if the variable is const.
223  if (!type.isConstQualified()) return 0;
224
225  // Furthermore, in C++ we have to worry about mutable fields:
226  // C++ [dcl.type.cv]p4:
227  //   Except that any class member declared mutable can be
228  //   modified, any attempt to modify a const object during its
229  //   lifetime results in undefined behavior.
230  if (CGM.getLangOpts().CPlusPlus && !isSafeForCXXConstantCapture(type))
231    return 0;
232
233  // If the variable doesn't have any initializer (shouldn't this be
234  // invalid?), it's not clear what we should do.  Maybe capture as
235  // zero?
236  const Expr *init = var->getInit();
237  if (!init) return 0;
238
239  return CGM.EmitConstantInit(*var, CGF);
240}
241
242/// Get the low bit of a nonzero character count.  This is the
243/// alignment of the nth byte if the 0th byte is universally aligned.
244static CharUnits getLowBit(CharUnits v) {
245  return CharUnits::fromQuantity(v.getQuantity() & (~v.getQuantity() + 1));
246}
247
248static void initializeForBlockHeader(CodeGenModule &CGM, CGBlockInfo &info,
249                             SmallVectorImpl<llvm::Type*> &elementTypes) {
250  ASTContext &C = CGM.getContext();
251
252  // The header is basically a 'struct { void *; int; int; void *; void *; }'.
253  CharUnits ptrSize, ptrAlign, intSize, intAlign;
254  llvm::tie(ptrSize, ptrAlign) = C.getTypeInfoInChars(C.VoidPtrTy);
255  llvm::tie(intSize, intAlign) = C.getTypeInfoInChars(C.IntTy);
256
257  // Are there crazy embedded platforms where this isn't true?
258  assert(intSize <= ptrSize && "layout assumptions horribly violated");
259
260  CharUnits headerSize = ptrSize;
261  if (2 * intSize < ptrAlign) headerSize += ptrSize;
262  else headerSize += 2 * intSize;
263  headerSize += 2 * ptrSize;
264
265  info.BlockAlign = ptrAlign;
266  info.BlockSize = headerSize;
267
268  assert(elementTypes.empty());
269  llvm::Type *i8p = CGM.getTypes().ConvertType(C.VoidPtrTy);
270  llvm::Type *intTy = CGM.getTypes().ConvertType(C.IntTy);
271  elementTypes.push_back(i8p);
272  elementTypes.push_back(intTy);
273  elementTypes.push_back(intTy);
274  elementTypes.push_back(i8p);
275  elementTypes.push_back(CGM.getBlockDescriptorType());
276
277  assert(elementTypes.size() == BlockHeaderSize);
278}
279
280/// Compute the layout of the given block.  Attempts to lay the block
281/// out with minimal space requirements.
282static void computeBlockInfo(CodeGenModule &CGM, CodeGenFunction *CGF,
283                             CGBlockInfo &info) {
284  ASTContext &C = CGM.getContext();
285  const BlockDecl *block = info.getBlockDecl();
286
287  SmallVector<llvm::Type*, 8> elementTypes;
288  initializeForBlockHeader(CGM, info, elementTypes);
289
290  if (!block->hasCaptures()) {
291    info.StructureType =
292      llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true);
293    info.CanBeGlobal = true;
294    return;
295  }
296
297  // Collect the layout chunks.
298  SmallVector<BlockLayoutChunk, 16> layout;
299  layout.reserve(block->capturesCXXThis() +
300                 (block->capture_end() - block->capture_begin()));
301
302  CharUnits maxFieldAlign;
303
304  // First, 'this'.
305  if (block->capturesCXXThis()) {
306    const DeclContext *DC = block->getDeclContext();
307    for (; isa<BlockDecl>(DC); DC = cast<BlockDecl>(DC)->getDeclContext())
308      ;
309    QualType thisType;
310    if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(DC))
311      thisType = C.getPointerType(C.getRecordType(RD));
312    else
313      thisType = cast<CXXMethodDecl>(DC)->getThisType(C);
314
315    llvm::Type *llvmType = CGM.getTypes().ConvertType(thisType);
316    std::pair<CharUnits,CharUnits> tinfo
317      = CGM.getContext().getTypeInfoInChars(thisType);
318    maxFieldAlign = std::max(maxFieldAlign, tinfo.second);
319
320    layout.push_back(BlockLayoutChunk(tinfo.second, tinfo.first, 0, llvmType));
321  }
322
323  // Next, all the block captures.
324  for (BlockDecl::capture_const_iterator ci = block->capture_begin(),
325         ce = block->capture_end(); ci != ce; ++ci) {
326    const VarDecl *variable = ci->getVariable();
327
328    if (ci->isByRef()) {
329      // We have to copy/dispose of the __block reference.
330      info.NeedsCopyDispose = true;
331
332      // Just use void* instead of a pointer to the byref type.
333      QualType byRefPtrTy = C.VoidPtrTy;
334
335      llvm::Type *llvmType = CGM.getTypes().ConvertType(byRefPtrTy);
336      std::pair<CharUnits,CharUnits> tinfo
337        = CGM.getContext().getTypeInfoInChars(byRefPtrTy);
338      maxFieldAlign = std::max(maxFieldAlign, tinfo.second);
339
340      layout.push_back(BlockLayoutChunk(tinfo.second, tinfo.first,
341                                        &*ci, llvmType));
342      continue;
343    }
344
345    // Otherwise, build a layout chunk with the size and alignment of
346    // the declaration.
347    if (llvm::Constant *constant = tryCaptureAsConstant(CGM, CGF, variable)) {
348      info.Captures[variable] = CGBlockInfo::Capture::makeConstant(constant);
349      continue;
350    }
351
352    // If we have a lifetime qualifier, honor it for capture purposes.
353    // That includes *not* copying it if it's __unsafe_unretained.
354    if (Qualifiers::ObjCLifetime lifetime
355          = variable->getType().getObjCLifetime()) {
356      switch (lifetime) {
357      case Qualifiers::OCL_None: llvm_unreachable("impossible");
358      case Qualifiers::OCL_ExplicitNone:
359      case Qualifiers::OCL_Autoreleasing:
360        break;
361
362      case Qualifiers::OCL_Strong:
363      case Qualifiers::OCL_Weak:
364        info.NeedsCopyDispose = true;
365      }
366
367    // Block pointers require copy/dispose.  So do Objective-C pointers.
368    } else if (variable->getType()->isObjCRetainableType()) {
369      info.NeedsCopyDispose = true;
370
371    // So do types that require non-trivial copy construction.
372    } else if (ci->hasCopyExpr()) {
373      info.NeedsCopyDispose = true;
374      info.HasCXXObject = true;
375
376    // And so do types with destructors.
377    } else if (CGM.getLangOpts().CPlusPlus) {
378      if (const CXXRecordDecl *record =
379            variable->getType()->getAsCXXRecordDecl()) {
380        if (!record->hasTrivialDestructor()) {
381          info.HasCXXObject = true;
382          info.NeedsCopyDispose = true;
383        }
384      }
385    }
386
387    QualType VT = variable->getType();
388    CharUnits size = C.getTypeSizeInChars(VT);
389    CharUnits align = C.getDeclAlign(variable);
390
391    maxFieldAlign = std::max(maxFieldAlign, align);
392
393    llvm::Type *llvmType =
394      CGM.getTypes().ConvertTypeForMem(VT);
395
396    layout.push_back(BlockLayoutChunk(align, size, &*ci, llvmType));
397  }
398
399  // If that was everything, we're done here.
400  if (layout.empty()) {
401    info.StructureType =
402      llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true);
403    info.CanBeGlobal = true;
404    return;
405  }
406
407  // Sort the layout by alignment.  We have to use a stable sort here
408  // to get reproducible results.  There should probably be an
409  // llvm::array_pod_stable_sort.
410  std::stable_sort(layout.begin(), layout.end());
411
412  CharUnits &blockSize = info.BlockSize;
413  info.BlockAlign = std::max(maxFieldAlign, info.BlockAlign);
414
415  // Assuming that the first byte in the header is maximally aligned,
416  // get the alignment of the first byte following the header.
417  CharUnits endAlign = getLowBit(blockSize);
418
419  // If the end of the header isn't satisfactorily aligned for the
420  // maximum thing, look for things that are okay with the header-end
421  // alignment, and keep appending them until we get something that's
422  // aligned right.  This algorithm is only guaranteed optimal if
423  // that condition is satisfied at some point; otherwise we can get
424  // things like:
425  //   header                 // next byte has alignment 4
426  //   something_with_size_5; // next byte has alignment 1
427  //   something_with_alignment_8;
428  // which has 7 bytes of padding, as opposed to the naive solution
429  // which might have less (?).
430  if (endAlign < maxFieldAlign) {
431    SmallVectorImpl<BlockLayoutChunk>::iterator
432      li = layout.begin() + 1, le = layout.end();
433
434    // Look for something that the header end is already
435    // satisfactorily aligned for.
436    for (; li != le && endAlign < li->Alignment; ++li)
437      ;
438
439    // If we found something that's naturally aligned for the end of
440    // the header, keep adding things...
441    if (li != le) {
442      SmallVectorImpl<BlockLayoutChunk>::iterator first = li;
443      for (; li != le; ++li) {
444        assert(endAlign >= li->Alignment);
445
446        li->setIndex(info, elementTypes.size());
447        elementTypes.push_back(li->Type);
448        blockSize += li->Size;
449        endAlign = getLowBit(blockSize);
450
451        // ...until we get to the alignment of the maximum field.
452        if (endAlign >= maxFieldAlign)
453          break;
454      }
455
456      // Don't re-append everything we just appended.
457      layout.erase(first, li);
458    }
459  }
460
461  assert(endAlign == getLowBit(blockSize));
462
463  // At this point, we just have to add padding if the end align still
464  // isn't aligned right.
465  if (endAlign < maxFieldAlign) {
466    CharUnits newBlockSize = blockSize.RoundUpToAlignment(maxFieldAlign);
467    CharUnits padding = newBlockSize - blockSize;
468
469    elementTypes.push_back(llvm::ArrayType::get(CGM.Int8Ty,
470                                                padding.getQuantity()));
471    blockSize = newBlockSize;
472    endAlign = getLowBit(blockSize); // might be > maxFieldAlign
473  }
474
475  assert(endAlign >= maxFieldAlign);
476  assert(endAlign == getLowBit(blockSize));
477
478  // Slam everything else on now.  This works because they have
479  // strictly decreasing alignment and we expect that size is always a
480  // multiple of alignment.
481  for (SmallVectorImpl<BlockLayoutChunk>::iterator
482         li = layout.begin(), le = layout.end(); li != le; ++li) {
483    assert(endAlign >= li->Alignment);
484    li->setIndex(info, elementTypes.size());
485    elementTypes.push_back(li->Type);
486    blockSize += li->Size;
487    endAlign = getLowBit(blockSize);
488  }
489
490  info.StructureType =
491    llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true);
492}
493
494/// Enter the scope of a block.  This should be run at the entrance to
495/// a full-expression so that the block's cleanups are pushed at the
496/// right place in the stack.
497static void enterBlockScope(CodeGenFunction &CGF, BlockDecl *block) {
498  assert(CGF.HaveInsertPoint());
499
500  // Allocate the block info and place it at the head of the list.
501  CGBlockInfo &blockInfo =
502    *new CGBlockInfo(block, CGF.CurFn->getName());
503  blockInfo.NextBlockInfo = CGF.FirstBlockInfo;
504  CGF.FirstBlockInfo = &blockInfo;
505
506  // Compute information about the layout, etc., of this block,
507  // pushing cleanups as necessary.
508  computeBlockInfo(CGF.CGM, &CGF, blockInfo);
509
510  // Nothing else to do if it can be global.
511  if (blockInfo.CanBeGlobal) return;
512
513  // Make the allocation for the block.
514  blockInfo.Address =
515    CGF.CreateTempAlloca(blockInfo.StructureType, "block");
516  blockInfo.Address->setAlignment(blockInfo.BlockAlign.getQuantity());
517
518  // If there are cleanups to emit, enter them (but inactive).
519  if (!blockInfo.NeedsCopyDispose) return;
520
521  // Walk through the captures (in order) and find the ones not
522  // captured by constant.
523  for (BlockDecl::capture_const_iterator ci = block->capture_begin(),
524         ce = block->capture_end(); ci != ce; ++ci) {
525    // Ignore __block captures; there's nothing special in the
526    // on-stack block that we need to do for them.
527    if (ci->isByRef()) continue;
528
529    // Ignore variables that are constant-captured.
530    const VarDecl *variable = ci->getVariable();
531    CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
532    if (capture.isConstant()) continue;
533
534    // Ignore objects that aren't destructed.
535    QualType::DestructionKind dtorKind =
536      variable->getType().isDestructedType();
537    if (dtorKind == QualType::DK_none) continue;
538
539    CodeGenFunction::Destroyer *destroyer;
540
541    // Block captures count as local values and have imprecise semantics.
542    // They also can't be arrays, so need to worry about that.
543    if (dtorKind == QualType::DK_objc_strong_lifetime) {
544      destroyer = CodeGenFunction::destroyARCStrongImprecise;
545    } else {
546      destroyer = CGF.getDestroyer(dtorKind);
547    }
548
549    // GEP down to the address.
550    llvm::Value *addr = CGF.Builder.CreateStructGEP(blockInfo.Address,
551                                                    capture.getIndex());
552
553    // We can use that GEP as the dominating IP.
554    if (!blockInfo.DominatingIP)
555      blockInfo.DominatingIP = cast<llvm::Instruction>(addr);
556
557    CleanupKind cleanupKind = InactiveNormalCleanup;
558    bool useArrayEHCleanup = CGF.needsEHCleanup(dtorKind);
559    if (useArrayEHCleanup)
560      cleanupKind = InactiveNormalAndEHCleanup;
561
562    CGF.pushDestroy(cleanupKind, addr, variable->getType(),
563                    destroyer, useArrayEHCleanup);
564
565    // Remember where that cleanup was.
566    capture.setCleanup(CGF.EHStack.stable_begin());
567  }
568}
569
570/// Enter a full-expression with a non-trivial number of objects to
571/// clean up.  This is in this file because, at the moment, the only
572/// kind of cleanup object is a BlockDecl*.
573void CodeGenFunction::enterNonTrivialFullExpression(const ExprWithCleanups *E) {
574  assert(E->getNumObjects() != 0);
575  ArrayRef<ExprWithCleanups::CleanupObject> cleanups = E->getObjects();
576  for (ArrayRef<ExprWithCleanups::CleanupObject>::iterator
577         i = cleanups.begin(), e = cleanups.end(); i != e; ++i) {
578    enterBlockScope(*this, *i);
579  }
580}
581
582/// Find the layout for the given block in a linked list and remove it.
583static CGBlockInfo *findAndRemoveBlockInfo(CGBlockInfo **head,
584                                           const BlockDecl *block) {
585  while (true) {
586    assert(head && *head);
587    CGBlockInfo *cur = *head;
588
589    // If this is the block we're looking for, splice it out of the list.
590    if (cur->getBlockDecl() == block) {
591      *head = cur->NextBlockInfo;
592      return cur;
593    }
594
595    head = &cur->NextBlockInfo;
596  }
597}
598
599/// Destroy a chain of block layouts.
600void CodeGenFunction::destroyBlockInfos(CGBlockInfo *head) {
601  assert(head && "destroying an empty chain");
602  do {
603    CGBlockInfo *cur = head;
604    head = cur->NextBlockInfo;
605    delete cur;
606  } while (head != 0);
607}
608
609/// Emit a block literal expression in the current function.
610llvm::Value *CodeGenFunction::EmitBlockLiteral(const BlockExpr *blockExpr) {
611  // If the block has no captures, we won't have a pre-computed
612  // layout for it.
613  if (!blockExpr->getBlockDecl()->hasCaptures()) {
614    CGBlockInfo blockInfo(blockExpr->getBlockDecl(), CurFn->getName());
615    computeBlockInfo(CGM, this, blockInfo);
616    blockInfo.BlockExpression = blockExpr;
617    return EmitBlockLiteral(blockInfo);
618  }
619
620  // Find the block info for this block and take ownership of it.
621  OwningPtr<CGBlockInfo> blockInfo;
622  blockInfo.reset(findAndRemoveBlockInfo(&FirstBlockInfo,
623                                         blockExpr->getBlockDecl()));
624
625  blockInfo->BlockExpression = blockExpr;
626  return EmitBlockLiteral(*blockInfo);
627}
628
629llvm::Value *CodeGenFunction::EmitBlockLiteral(const CGBlockInfo &blockInfo) {
630  // Using the computed layout, generate the actual block function.
631  bool isLambdaConv = blockInfo.getBlockDecl()->isConversionFromLambda();
632  llvm::Constant *blockFn
633    = CodeGenFunction(CGM, true).GenerateBlockFunction(CurGD, blockInfo,
634                                                 CurFuncDecl, LocalDeclMap,
635                                                 isLambdaConv);
636  blockFn = llvm::ConstantExpr::getBitCast(blockFn, VoidPtrTy);
637
638  // If there is nothing to capture, we can emit this as a global block.
639  if (blockInfo.CanBeGlobal)
640    return buildGlobalBlock(CGM, blockInfo, blockFn);
641
642  // Otherwise, we have to emit this as a local block.
643
644  llvm::Constant *isa = CGM.getNSConcreteStackBlock();
645  isa = llvm::ConstantExpr::getBitCast(isa, VoidPtrTy);
646
647  // Build the block descriptor.
648  llvm::Constant *descriptor = buildBlockDescriptor(CGM, blockInfo);
649
650  llvm::AllocaInst *blockAddr = blockInfo.Address;
651  assert(blockAddr && "block has no address!");
652
653  // Compute the initial on-stack block flags.
654  BlockFlags flags = BLOCK_HAS_SIGNATURE;
655  if (blockInfo.NeedsCopyDispose) flags |= BLOCK_HAS_COPY_DISPOSE;
656  if (blockInfo.HasCXXObject) flags |= BLOCK_HAS_CXX_OBJ;
657  if (blockInfo.UsesStret) flags |= BLOCK_USE_STRET;
658
659  // Initialize the block literal.
660  Builder.CreateStore(isa, Builder.CreateStructGEP(blockAddr, 0, "block.isa"));
661  Builder.CreateStore(llvm::ConstantInt::get(IntTy, flags.getBitMask()),
662                      Builder.CreateStructGEP(blockAddr, 1, "block.flags"));
663  Builder.CreateStore(llvm::ConstantInt::get(IntTy, 0),
664                      Builder.CreateStructGEP(blockAddr, 2, "block.reserved"));
665  Builder.CreateStore(blockFn, Builder.CreateStructGEP(blockAddr, 3,
666                                                       "block.invoke"));
667  Builder.CreateStore(descriptor, Builder.CreateStructGEP(blockAddr, 4,
668                                                          "block.descriptor"));
669
670  // Finally, capture all the values into the block.
671  const BlockDecl *blockDecl = blockInfo.getBlockDecl();
672
673  // First, 'this'.
674  if (blockDecl->capturesCXXThis()) {
675    llvm::Value *addr = Builder.CreateStructGEP(blockAddr,
676                                                blockInfo.CXXThisIndex,
677                                                "block.captured-this.addr");
678    Builder.CreateStore(LoadCXXThis(), addr);
679  }
680
681  // Next, captured variables.
682  for (BlockDecl::capture_const_iterator ci = blockDecl->capture_begin(),
683         ce = blockDecl->capture_end(); ci != ce; ++ci) {
684    const VarDecl *variable = ci->getVariable();
685    const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
686
687    // Ignore constant captures.
688    if (capture.isConstant()) continue;
689
690    QualType type = variable->getType();
691
692    // This will be a [[type]]*, except that a byref entry will just be
693    // an i8**.
694    llvm::Value *blockField =
695      Builder.CreateStructGEP(blockAddr, capture.getIndex(),
696                              "block.captured");
697
698    // Compute the address of the thing we're going to move into the
699    // block literal.
700    llvm::Value *src;
701    if (BlockInfo && ci->isNested()) {
702      // We need to use the capture from the enclosing block.
703      const CGBlockInfo::Capture &enclosingCapture =
704        BlockInfo->getCapture(variable);
705
706      // This is a [[type]]*, except that a byref entry wil just be an i8**.
707      src = Builder.CreateStructGEP(LoadBlockStruct(),
708                                    enclosingCapture.getIndex(),
709                                    "block.capture.addr");
710    } else if (blockDecl->isConversionFromLambda()) {
711      // The lambda capture in a lambda's conversion-to-block-pointer is
712      // special; we'll simply emit it directly.
713      src = 0;
714    } else {
715      // This is a [[type]]*.
716      src = LocalDeclMap[variable];
717    }
718
719    // For byrefs, we just write the pointer to the byref struct into
720    // the block field.  There's no need to chase the forwarding
721    // pointer at this point, since we're building something that will
722    // live a shorter life than the stack byref anyway.
723    if (ci->isByRef()) {
724      // Get a void* that points to the byref struct.
725      if (ci->isNested())
726        src = Builder.CreateLoad(src, "byref.capture");
727      else
728        src = Builder.CreateBitCast(src, VoidPtrTy);
729
730      // Write that void* into the capture field.
731      Builder.CreateStore(src, blockField);
732
733    // If we have a copy constructor, evaluate that into the block field.
734    } else if (const Expr *copyExpr = ci->getCopyExpr()) {
735      if (blockDecl->isConversionFromLambda()) {
736        // If we have a lambda conversion, emit the expression
737        // directly into the block instead.
738        CharUnits Align = getContext().getTypeAlignInChars(type);
739        AggValueSlot Slot =
740            AggValueSlot::forAddr(blockField, Align, Qualifiers(),
741                                  AggValueSlot::IsDestructed,
742                                  AggValueSlot::DoesNotNeedGCBarriers,
743                                  AggValueSlot::IsNotAliased);
744        EmitAggExpr(copyExpr, Slot);
745      } else {
746        EmitSynthesizedCXXCopyCtor(blockField, src, copyExpr);
747      }
748
749    // If it's a reference variable, copy the reference into the block field.
750    } else if (type->isReferenceType()) {
751      Builder.CreateStore(Builder.CreateLoad(src, "ref.val"), blockField);
752
753    // Otherwise, fake up a POD copy into the block field.
754    } else {
755      // Fake up a new variable so that EmitScalarInit doesn't think
756      // we're referring to the variable in its own initializer.
757      ImplicitParamDecl blockFieldPseudoVar(/*DC*/ 0, SourceLocation(),
758                                            /*name*/ 0, type);
759
760      // We use one of these or the other depending on whether the
761      // reference is nested.
762      DeclRefExpr declRef(const_cast<VarDecl*>(variable),
763                          /*refersToEnclosing*/ ci->isNested(), type,
764                          VK_LValue, SourceLocation());
765
766      ImplicitCastExpr l2r(ImplicitCastExpr::OnStack, type, CK_LValueToRValue,
767                           &declRef, VK_RValue);
768      EmitExprAsInit(&l2r, &blockFieldPseudoVar,
769                     MakeAddrLValue(blockField, type,
770                                    getContext().getDeclAlign(variable)),
771                     /*captured by init*/ false);
772    }
773
774    // Activate the cleanup if layout pushed one.
775    if (!ci->isByRef()) {
776      EHScopeStack::stable_iterator cleanup = capture.getCleanup();
777      if (cleanup.isValid())
778        ActivateCleanupBlock(cleanup, blockInfo.DominatingIP);
779    }
780  }
781
782  // Cast to the converted block-pointer type, which happens (somewhat
783  // unfortunately) to be a pointer to function type.
784  llvm::Value *result =
785    Builder.CreateBitCast(blockAddr,
786                          ConvertType(blockInfo.getBlockExpr()->getType()));
787
788  return result;
789}
790
791
792llvm::Type *CodeGenModule::getBlockDescriptorType() {
793  if (BlockDescriptorType)
794    return BlockDescriptorType;
795
796  llvm::Type *UnsignedLongTy =
797    getTypes().ConvertType(getContext().UnsignedLongTy);
798
799  // struct __block_descriptor {
800  //   unsigned long reserved;
801  //   unsigned long block_size;
802  //
803  //   // later, the following will be added
804  //
805  //   struct {
806  //     void (*copyHelper)();
807  //     void (*copyHelper)();
808  //   } helpers;                // !!! optional
809  //
810  //   const char *signature;   // the block signature
811  //   const char *layout;      // reserved
812  // };
813  BlockDescriptorType =
814    llvm::StructType::create("struct.__block_descriptor",
815                             UnsignedLongTy, UnsignedLongTy, NULL);
816
817  // Now form a pointer to that.
818  BlockDescriptorType = llvm::PointerType::getUnqual(BlockDescriptorType);
819  return BlockDescriptorType;
820}
821
822llvm::Type *CodeGenModule::getGenericBlockLiteralType() {
823  if (GenericBlockLiteralType)
824    return GenericBlockLiteralType;
825
826  llvm::Type *BlockDescPtrTy = getBlockDescriptorType();
827
828  // struct __block_literal_generic {
829  //   void *__isa;
830  //   int __flags;
831  //   int __reserved;
832  //   void (*__invoke)(void *);
833  //   struct __block_descriptor *__descriptor;
834  // };
835  GenericBlockLiteralType =
836    llvm::StructType::create("struct.__block_literal_generic",
837                             VoidPtrTy, IntTy, IntTy, VoidPtrTy,
838                             BlockDescPtrTy, NULL);
839
840  return GenericBlockLiteralType;
841}
842
843
844RValue CodeGenFunction::EmitBlockCallExpr(const CallExpr* E,
845                                          ReturnValueSlot ReturnValue) {
846  const BlockPointerType *BPT =
847    E->getCallee()->getType()->getAs<BlockPointerType>();
848
849  llvm::Value *Callee = EmitScalarExpr(E->getCallee());
850
851  // Get a pointer to the generic block literal.
852  llvm::Type *BlockLiteralTy =
853    llvm::PointerType::getUnqual(CGM.getGenericBlockLiteralType());
854
855  // Bitcast the callee to a block literal.
856  llvm::Value *BlockLiteral =
857    Builder.CreateBitCast(Callee, BlockLiteralTy, "block.literal");
858
859  // Get the function pointer from the literal.
860  llvm::Value *FuncPtr = Builder.CreateStructGEP(BlockLiteral, 3);
861
862  BlockLiteral = Builder.CreateBitCast(BlockLiteral, VoidPtrTy);
863
864  // Add the block literal.
865  CallArgList Args;
866  Args.add(RValue::get(BlockLiteral), getContext().VoidPtrTy);
867
868  QualType FnType = BPT->getPointeeType();
869
870  // And the rest of the arguments.
871  EmitCallArgs(Args, FnType->getAs<FunctionProtoType>(),
872               E->arg_begin(), E->arg_end());
873
874  // Load the function.
875  llvm::Value *Func = Builder.CreateLoad(FuncPtr);
876
877  const FunctionType *FuncTy = FnType->castAs<FunctionType>();
878  const CGFunctionInfo &FnInfo =
879    CGM.getTypes().arrangeFreeFunctionCall(Args, FuncTy);
880
881  // Cast the function pointer to the right type.
882  llvm::Type *BlockFTy = CGM.getTypes().GetFunctionType(FnInfo);
883
884  llvm::Type *BlockFTyPtr = llvm::PointerType::getUnqual(BlockFTy);
885  Func = Builder.CreateBitCast(Func, BlockFTyPtr);
886
887  // And call the block.
888  return EmitCall(FnInfo, Func, ReturnValue, Args);
889}
890
891llvm::Value *CodeGenFunction::GetAddrOfBlockDecl(const VarDecl *variable,
892                                                 bool isByRef) {
893  assert(BlockInfo && "evaluating block ref without block information?");
894  const CGBlockInfo::Capture &capture = BlockInfo->getCapture(variable);
895
896  // Handle constant captures.
897  if (capture.isConstant()) return LocalDeclMap[variable];
898
899  llvm::Value *addr =
900    Builder.CreateStructGEP(LoadBlockStruct(), capture.getIndex(),
901                            "block.capture.addr");
902
903  if (isByRef) {
904    // addr should be a void** right now.  Load, then cast the result
905    // to byref*.
906
907    addr = Builder.CreateLoad(addr);
908    llvm::PointerType *byrefPointerType
909      = llvm::PointerType::get(BuildByRefType(variable), 0);
910    addr = Builder.CreateBitCast(addr, byrefPointerType,
911                                 "byref.addr");
912
913    // Follow the forwarding pointer.
914    addr = Builder.CreateStructGEP(addr, 1, "byref.forwarding");
915    addr = Builder.CreateLoad(addr, "byref.addr.forwarded");
916
917    // Cast back to byref* and GEP over to the actual object.
918    addr = Builder.CreateBitCast(addr, byrefPointerType);
919    addr = Builder.CreateStructGEP(addr, getByRefValueLLVMField(variable),
920                                   variable->getNameAsString());
921  }
922
923  if (variable->getType()->isReferenceType())
924    addr = Builder.CreateLoad(addr, "ref.tmp");
925
926  return addr;
927}
928
929llvm::Constant *
930CodeGenModule::GetAddrOfGlobalBlock(const BlockExpr *blockExpr,
931                                    const char *name) {
932  CGBlockInfo blockInfo(blockExpr->getBlockDecl(), name);
933  blockInfo.BlockExpression = blockExpr;
934
935  // Compute information about the layout, etc., of this block.
936  computeBlockInfo(*this, 0, blockInfo);
937
938  // Using that metadata, generate the actual block function.
939  llvm::Constant *blockFn;
940  {
941    llvm::DenseMap<const Decl*, llvm::Value*> LocalDeclMap;
942    blockFn = CodeGenFunction(*this).GenerateBlockFunction(GlobalDecl(),
943                                                           blockInfo,
944                                                           0, LocalDeclMap,
945                                                           false);
946  }
947  blockFn = llvm::ConstantExpr::getBitCast(blockFn, VoidPtrTy);
948
949  return buildGlobalBlock(*this, blockInfo, blockFn);
950}
951
952static llvm::Constant *buildGlobalBlock(CodeGenModule &CGM,
953                                        const CGBlockInfo &blockInfo,
954                                        llvm::Constant *blockFn) {
955  assert(blockInfo.CanBeGlobal);
956
957  // Generate the constants for the block literal initializer.
958  llvm::Constant *fields[BlockHeaderSize];
959
960  // isa
961  fields[0] = CGM.getNSConcreteGlobalBlock();
962
963  // __flags
964  BlockFlags flags = BLOCK_IS_GLOBAL | BLOCK_HAS_SIGNATURE;
965  if (blockInfo.UsesStret) flags |= BLOCK_USE_STRET;
966
967  fields[1] = llvm::ConstantInt::get(CGM.IntTy, flags.getBitMask());
968
969  // Reserved
970  fields[2] = llvm::Constant::getNullValue(CGM.IntTy);
971
972  // Function
973  fields[3] = blockFn;
974
975  // Descriptor
976  fields[4] = buildBlockDescriptor(CGM, blockInfo);
977
978  llvm::Constant *init = llvm::ConstantStruct::getAnon(fields);
979
980  llvm::GlobalVariable *literal =
981    new llvm::GlobalVariable(CGM.getModule(),
982                             init->getType(),
983                             /*constant*/ true,
984                             llvm::GlobalVariable::InternalLinkage,
985                             init,
986                             "__block_literal_global");
987  literal->setAlignment(blockInfo.BlockAlign.getQuantity());
988
989  // Return a constant of the appropriately-casted type.
990  llvm::Type *requiredType =
991    CGM.getTypes().ConvertType(blockInfo.getBlockExpr()->getType());
992  return llvm::ConstantExpr::getBitCast(literal, requiredType);
993}
994
995llvm::Function *
996CodeGenFunction::GenerateBlockFunction(GlobalDecl GD,
997                                       const CGBlockInfo &blockInfo,
998                                       const Decl *outerFnDecl,
999                                       const DeclMapTy &ldm,
1000                                       bool IsLambdaConversionToBlock) {
1001  const BlockDecl *blockDecl = blockInfo.getBlockDecl();
1002
1003  // Check if we should generate debug info for this block function.
1004  if (CGM.getModuleDebugInfo())
1005    DebugInfo = CGM.getModuleDebugInfo();
1006  CurGD = GD;
1007
1008  BlockInfo = &blockInfo;
1009
1010  // Arrange for local static and local extern declarations to appear
1011  // to be local to this function as well, in case they're directly
1012  // referenced in a block.
1013  for (DeclMapTy::const_iterator i = ldm.begin(), e = ldm.end(); i != e; ++i) {
1014    const VarDecl *var = dyn_cast<VarDecl>(i->first);
1015    if (var && !var->hasLocalStorage())
1016      LocalDeclMap[var] = i->second;
1017  }
1018
1019  // Begin building the function declaration.
1020
1021  // Build the argument list.
1022  FunctionArgList args;
1023
1024  // The first argument is the block pointer.  Just take it as a void*
1025  // and cast it later.
1026  QualType selfTy = getContext().VoidPtrTy;
1027  IdentifierInfo *II = &CGM.getContext().Idents.get(".block_descriptor");
1028
1029  ImplicitParamDecl selfDecl(const_cast<BlockDecl*>(blockDecl),
1030                             SourceLocation(), II, selfTy);
1031  args.push_back(&selfDecl);
1032
1033  // Now add the rest of the parameters.
1034  for (BlockDecl::param_const_iterator i = blockDecl->param_begin(),
1035       e = blockDecl->param_end(); i != e; ++i)
1036    args.push_back(*i);
1037
1038  // Create the function declaration.
1039  const FunctionProtoType *fnType = blockInfo.getBlockExpr()->getFunctionType();
1040  const CGFunctionInfo &fnInfo =
1041    CGM.getTypes().arrangeFunctionDeclaration(fnType->getResultType(), args,
1042                                              fnType->getExtInfo(),
1043                                              fnType->isVariadic());
1044  if (CGM.ReturnTypeUsesSRet(fnInfo))
1045    blockInfo.UsesStret = true;
1046
1047  llvm::FunctionType *fnLLVMType = CGM.getTypes().GetFunctionType(fnInfo);
1048
1049  MangleBuffer name;
1050  CGM.getBlockMangledName(GD, name, blockDecl);
1051  llvm::Function *fn =
1052    llvm::Function::Create(fnLLVMType, llvm::GlobalValue::InternalLinkage,
1053                           name.getString(), &CGM.getModule());
1054  CGM.SetInternalFunctionAttributes(blockDecl, fn, fnInfo);
1055
1056  // Begin generating the function.
1057  StartFunction(blockDecl, fnType->getResultType(), fn, fnInfo, args,
1058                blockInfo.getBlockExpr()->getBody()->getLocStart());
1059  CurFuncDecl = outerFnDecl; // StartFunction sets this to blockDecl
1060
1061  // Okay.  Undo some of what StartFunction did.
1062
1063  // Pull the 'self' reference out of the local decl map.
1064  llvm::Value *blockAddr = LocalDeclMap[&selfDecl];
1065  LocalDeclMap.erase(&selfDecl);
1066  BlockPointer = Builder.CreateBitCast(blockAddr,
1067                                       blockInfo.StructureType->getPointerTo(),
1068                                       "block");
1069
1070  // If we have a C++ 'this' reference, go ahead and force it into
1071  // existence now.
1072  if (blockDecl->capturesCXXThis()) {
1073    llvm::Value *addr = Builder.CreateStructGEP(BlockPointer,
1074                                                blockInfo.CXXThisIndex,
1075                                                "block.captured-this");
1076    CXXThisValue = Builder.CreateLoad(addr, "this");
1077  }
1078
1079  // LoadObjCSelf() expects there to be an entry for 'self' in LocalDeclMap;
1080  // appease it.
1081  if (const ObjCMethodDecl *method
1082        = dyn_cast_or_null<ObjCMethodDecl>(CurFuncDecl)) {
1083    const VarDecl *self = method->getSelfDecl();
1084
1085    // There might not be a capture for 'self', but if there is...
1086    if (blockInfo.Captures.count(self)) {
1087      const CGBlockInfo::Capture &capture = blockInfo.getCapture(self);
1088      llvm::Value *selfAddr = Builder.CreateStructGEP(BlockPointer,
1089                                                      capture.getIndex(),
1090                                                      "block.captured-self");
1091      LocalDeclMap[self] = selfAddr;
1092    }
1093  }
1094
1095  // Also force all the constant captures.
1096  for (BlockDecl::capture_const_iterator ci = blockDecl->capture_begin(),
1097         ce = blockDecl->capture_end(); ci != ce; ++ci) {
1098    const VarDecl *variable = ci->getVariable();
1099    const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
1100    if (!capture.isConstant()) continue;
1101
1102    unsigned align = getContext().getDeclAlign(variable).getQuantity();
1103
1104    llvm::AllocaInst *alloca =
1105      CreateMemTemp(variable->getType(), "block.captured-const");
1106    alloca->setAlignment(align);
1107
1108    Builder.CreateStore(capture.getConstant(), alloca, align);
1109
1110    LocalDeclMap[variable] = alloca;
1111  }
1112
1113  // Save a spot to insert the debug information for all the DeclRefExprs.
1114  llvm::BasicBlock *entry = Builder.GetInsertBlock();
1115  llvm::BasicBlock::iterator entry_ptr = Builder.GetInsertPoint();
1116  --entry_ptr;
1117
1118  if (IsLambdaConversionToBlock)
1119    EmitLambdaBlockInvokeBody();
1120  else
1121    EmitStmt(blockDecl->getBody());
1122
1123  // Remember where we were...
1124  llvm::BasicBlock *resume = Builder.GetInsertBlock();
1125
1126  // Go back to the entry.
1127  ++entry_ptr;
1128  Builder.SetInsertPoint(entry, entry_ptr);
1129
1130  // Emit debug information for all the DeclRefExprs.
1131  // FIXME: also for 'this'
1132  if (CGDebugInfo *DI = getDebugInfo()) {
1133    for (BlockDecl::capture_const_iterator ci = blockDecl->capture_begin(),
1134           ce = blockDecl->capture_end(); ci != ce; ++ci) {
1135      const VarDecl *variable = ci->getVariable();
1136      DI->EmitLocation(Builder, variable->getLocation());
1137
1138      if (CGM.getCodeGenOpts().DebugInfo >= CodeGenOptions::LimitedDebugInfo) {
1139        const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
1140        if (capture.isConstant()) {
1141          DI->EmitDeclareOfAutoVariable(variable, LocalDeclMap[variable],
1142                                        Builder);
1143          continue;
1144        }
1145
1146        DI->EmitDeclareOfBlockDeclRefVariable(variable, BlockPointer,
1147                                              Builder, blockInfo);
1148      }
1149    }
1150  }
1151
1152  // And resume where we left off.
1153  if (resume == 0)
1154    Builder.ClearInsertionPoint();
1155  else
1156    Builder.SetInsertPoint(resume);
1157
1158  FinishFunction(cast<CompoundStmt>(blockDecl->getBody())->getRBracLoc());
1159
1160  return fn;
1161}
1162
1163/*
1164    notes.push_back(HelperInfo());
1165    HelperInfo &note = notes.back();
1166    note.index = capture.getIndex();
1167    note.RequiresCopying = (ci->hasCopyExpr() || BlockRequiresCopying(type));
1168    note.cxxbar_import = ci->getCopyExpr();
1169
1170    if (ci->isByRef()) {
1171      note.flag = BLOCK_FIELD_IS_BYREF;
1172      if (type.isObjCGCWeak())
1173        note.flag |= BLOCK_FIELD_IS_WEAK;
1174    } else if (type->isBlockPointerType()) {
1175      note.flag = BLOCK_FIELD_IS_BLOCK;
1176    } else {
1177      note.flag = BLOCK_FIELD_IS_OBJECT;
1178    }
1179 */
1180
1181
1182
1183llvm::Constant *
1184CodeGenFunction::GenerateCopyHelperFunction(const CGBlockInfo &blockInfo) {
1185  ASTContext &C = getContext();
1186
1187  FunctionArgList args;
1188  ImplicitParamDecl dstDecl(0, SourceLocation(), 0, C.VoidPtrTy);
1189  args.push_back(&dstDecl);
1190  ImplicitParamDecl srcDecl(0, SourceLocation(), 0, C.VoidPtrTy);
1191  args.push_back(&srcDecl);
1192
1193  const CGFunctionInfo &FI =
1194    CGM.getTypes().arrangeFunctionDeclaration(C.VoidTy, args,
1195                                              FunctionType::ExtInfo(),
1196                                              /*variadic*/ false);
1197
1198  // FIXME: it would be nice if these were mergeable with things with
1199  // identical semantics.
1200  llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI);
1201
1202  llvm::Function *Fn =
1203    llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
1204                           "__copy_helper_block_", &CGM.getModule());
1205
1206  IdentifierInfo *II
1207    = &CGM.getContext().Idents.get("__copy_helper_block_");
1208
1209  // Check if we should generate debug info for this block helper function.
1210  if (CGM.getModuleDebugInfo())
1211    DebugInfo = CGM.getModuleDebugInfo();
1212
1213  FunctionDecl *FD = FunctionDecl::Create(C,
1214                                          C.getTranslationUnitDecl(),
1215                                          SourceLocation(),
1216                                          SourceLocation(), II, C.VoidTy, 0,
1217                                          SC_Static,
1218                                          SC_None,
1219                                          false,
1220                                          false);
1221  StartFunction(FD, C.VoidTy, Fn, FI, args, SourceLocation());
1222
1223  llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo();
1224
1225  llvm::Value *src = GetAddrOfLocalVar(&srcDecl);
1226  src = Builder.CreateLoad(src);
1227  src = Builder.CreateBitCast(src, structPtrTy, "block.source");
1228
1229  llvm::Value *dst = GetAddrOfLocalVar(&dstDecl);
1230  dst = Builder.CreateLoad(dst);
1231  dst = Builder.CreateBitCast(dst, structPtrTy, "block.dest");
1232
1233  const BlockDecl *blockDecl = blockInfo.getBlockDecl();
1234
1235  for (BlockDecl::capture_const_iterator ci = blockDecl->capture_begin(),
1236         ce = blockDecl->capture_end(); ci != ce; ++ci) {
1237    const VarDecl *variable = ci->getVariable();
1238    QualType type = variable->getType();
1239
1240    const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
1241    if (capture.isConstant()) continue;
1242
1243    const Expr *copyExpr = ci->getCopyExpr();
1244    BlockFieldFlags flags;
1245
1246    bool isARCWeakCapture = false;
1247
1248    if (copyExpr) {
1249      assert(!ci->isByRef());
1250      // don't bother computing flags
1251
1252    } else if (ci->isByRef()) {
1253      flags = BLOCK_FIELD_IS_BYREF;
1254      if (type.isObjCGCWeak())
1255        flags |= BLOCK_FIELD_IS_WEAK;
1256
1257    } else if (type->isObjCRetainableType()) {
1258      flags = BLOCK_FIELD_IS_OBJECT;
1259      if (type->isBlockPointerType())
1260        flags = BLOCK_FIELD_IS_BLOCK;
1261
1262      // Special rules for ARC captures:
1263      if (getLangOpts().ObjCAutoRefCount) {
1264        Qualifiers qs = type.getQualifiers();
1265
1266        // Don't generate special copy logic for a captured object
1267        // unless it's __strong or __weak.
1268        if (!qs.hasStrongOrWeakObjCLifetime())
1269          continue;
1270
1271        // Support __weak direct captures.
1272        if (qs.getObjCLifetime() == Qualifiers::OCL_Weak)
1273          isARCWeakCapture = true;
1274      }
1275    } else {
1276      continue;
1277    }
1278
1279    unsigned index = capture.getIndex();
1280    llvm::Value *srcField = Builder.CreateStructGEP(src, index);
1281    llvm::Value *dstField = Builder.CreateStructGEP(dst, index);
1282
1283    // If there's an explicit copy expression, we do that.
1284    if (copyExpr) {
1285      EmitSynthesizedCXXCopyCtor(dstField, srcField, copyExpr);
1286    } else if (isARCWeakCapture) {
1287      EmitARCCopyWeak(dstField, srcField);
1288    } else {
1289      llvm::Value *srcValue = Builder.CreateLoad(srcField, "blockcopy.src");
1290      srcValue = Builder.CreateBitCast(srcValue, VoidPtrTy);
1291      llvm::Value *dstAddr = Builder.CreateBitCast(dstField, VoidPtrTy);
1292      Builder.CreateCall3(CGM.getBlockObjectAssign(), dstAddr, srcValue,
1293                          llvm::ConstantInt::get(Int32Ty, flags.getBitMask()));
1294    }
1295  }
1296
1297  FinishFunction();
1298
1299  return llvm::ConstantExpr::getBitCast(Fn, VoidPtrTy);
1300}
1301
1302llvm::Constant *
1303CodeGenFunction::GenerateDestroyHelperFunction(const CGBlockInfo &blockInfo) {
1304  ASTContext &C = getContext();
1305
1306  FunctionArgList args;
1307  ImplicitParamDecl srcDecl(0, SourceLocation(), 0, C.VoidPtrTy);
1308  args.push_back(&srcDecl);
1309
1310  const CGFunctionInfo &FI =
1311    CGM.getTypes().arrangeFunctionDeclaration(C.VoidTy, args,
1312                                              FunctionType::ExtInfo(),
1313                                              /*variadic*/ false);
1314
1315  // FIXME: We'd like to put these into a mergable by content, with
1316  // internal linkage.
1317  llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI);
1318
1319  llvm::Function *Fn =
1320    llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
1321                           "__destroy_helper_block_", &CGM.getModule());
1322
1323  // Check if we should generate debug info for this block destroy function.
1324  if (CGM.getModuleDebugInfo())
1325    DebugInfo = CGM.getModuleDebugInfo();
1326
1327  IdentifierInfo *II
1328    = &CGM.getContext().Idents.get("__destroy_helper_block_");
1329
1330  FunctionDecl *FD = FunctionDecl::Create(C, C.getTranslationUnitDecl(),
1331                                          SourceLocation(),
1332                                          SourceLocation(), II, C.VoidTy, 0,
1333                                          SC_Static,
1334                                          SC_None,
1335                                          false, false);
1336  StartFunction(FD, C.VoidTy, Fn, FI, args, SourceLocation());
1337
1338  llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo();
1339
1340  llvm::Value *src = GetAddrOfLocalVar(&srcDecl);
1341  src = Builder.CreateLoad(src);
1342  src = Builder.CreateBitCast(src, structPtrTy, "block");
1343
1344  const BlockDecl *blockDecl = blockInfo.getBlockDecl();
1345
1346  CodeGenFunction::RunCleanupsScope cleanups(*this);
1347
1348  for (BlockDecl::capture_const_iterator ci = blockDecl->capture_begin(),
1349         ce = blockDecl->capture_end(); ci != ce; ++ci) {
1350    const VarDecl *variable = ci->getVariable();
1351    QualType type = variable->getType();
1352
1353    const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
1354    if (capture.isConstant()) continue;
1355
1356    BlockFieldFlags flags;
1357    const CXXDestructorDecl *dtor = 0;
1358
1359    bool isARCWeakCapture = false;
1360
1361    if (ci->isByRef()) {
1362      flags = BLOCK_FIELD_IS_BYREF;
1363      if (type.isObjCGCWeak())
1364        flags |= BLOCK_FIELD_IS_WEAK;
1365    } else if (const CXXRecordDecl *record = type->getAsCXXRecordDecl()) {
1366      if (record->hasTrivialDestructor())
1367        continue;
1368      dtor = record->getDestructor();
1369    } else if (type->isObjCRetainableType()) {
1370      flags = BLOCK_FIELD_IS_OBJECT;
1371      if (type->isBlockPointerType())
1372        flags = BLOCK_FIELD_IS_BLOCK;
1373
1374      // Special rules for ARC captures.
1375      if (getLangOpts().ObjCAutoRefCount) {
1376        Qualifiers qs = type.getQualifiers();
1377
1378        // Don't generate special dispose logic for a captured object
1379        // unless it's __strong or __weak.
1380        if (!qs.hasStrongOrWeakObjCLifetime())
1381          continue;
1382
1383        // Support __weak direct captures.
1384        if (qs.getObjCLifetime() == Qualifiers::OCL_Weak)
1385          isARCWeakCapture = true;
1386      }
1387    } else {
1388      continue;
1389    }
1390
1391    unsigned index = capture.getIndex();
1392    llvm::Value *srcField = Builder.CreateStructGEP(src, index);
1393
1394    // If there's an explicit copy expression, we do that.
1395    if (dtor) {
1396      PushDestructorCleanup(dtor, srcField);
1397
1398    // If this is a __weak capture, emit the release directly.
1399    } else if (isARCWeakCapture) {
1400      EmitARCDestroyWeak(srcField);
1401
1402    // Otherwise we call _Block_object_dispose.  It wouldn't be too
1403    // hard to just emit this as a cleanup if we wanted to make sure
1404    // that things were done in reverse.
1405    } else {
1406      llvm::Value *value = Builder.CreateLoad(srcField);
1407      value = Builder.CreateBitCast(value, VoidPtrTy);
1408      BuildBlockRelease(value, flags);
1409    }
1410  }
1411
1412  cleanups.ForceCleanup();
1413
1414  FinishFunction();
1415
1416  return llvm::ConstantExpr::getBitCast(Fn, VoidPtrTy);
1417}
1418
1419namespace {
1420
1421/// Emits the copy/dispose helper functions for a __block object of id type.
1422class ObjectByrefHelpers : public CodeGenModule::ByrefHelpers {
1423  BlockFieldFlags Flags;
1424
1425public:
1426  ObjectByrefHelpers(CharUnits alignment, BlockFieldFlags flags)
1427    : ByrefHelpers(alignment), Flags(flags) {}
1428
1429  void emitCopy(CodeGenFunction &CGF, llvm::Value *destField,
1430                llvm::Value *srcField) {
1431    destField = CGF.Builder.CreateBitCast(destField, CGF.VoidPtrTy);
1432
1433    srcField = CGF.Builder.CreateBitCast(srcField, CGF.VoidPtrPtrTy);
1434    llvm::Value *srcValue = CGF.Builder.CreateLoad(srcField);
1435
1436    unsigned flags = (Flags | BLOCK_BYREF_CALLER).getBitMask();
1437
1438    llvm::Value *flagsVal = llvm::ConstantInt::get(CGF.Int32Ty, flags);
1439    llvm::Value *fn = CGF.CGM.getBlockObjectAssign();
1440    CGF.Builder.CreateCall3(fn, destField, srcValue, flagsVal);
1441  }
1442
1443  void emitDispose(CodeGenFunction &CGF, llvm::Value *field) {
1444    field = CGF.Builder.CreateBitCast(field, CGF.Int8PtrTy->getPointerTo(0));
1445    llvm::Value *value = CGF.Builder.CreateLoad(field);
1446
1447    CGF.BuildBlockRelease(value, Flags | BLOCK_BYREF_CALLER);
1448  }
1449
1450  void profileImpl(llvm::FoldingSetNodeID &id) const {
1451    id.AddInteger(Flags.getBitMask());
1452  }
1453};
1454
1455/// Emits the copy/dispose helpers for an ARC __block __weak variable.
1456class ARCWeakByrefHelpers : public CodeGenModule::ByrefHelpers {
1457public:
1458  ARCWeakByrefHelpers(CharUnits alignment) : ByrefHelpers(alignment) {}
1459
1460  void emitCopy(CodeGenFunction &CGF, llvm::Value *destField,
1461                llvm::Value *srcField) {
1462    CGF.EmitARCMoveWeak(destField, srcField);
1463  }
1464
1465  void emitDispose(CodeGenFunction &CGF, llvm::Value *field) {
1466    CGF.EmitARCDestroyWeak(field);
1467  }
1468
1469  void profileImpl(llvm::FoldingSetNodeID &id) const {
1470    // 0 is distinguishable from all pointers and byref flags
1471    id.AddInteger(0);
1472  }
1473};
1474
1475/// Emits the copy/dispose helpers for an ARC __block __strong variable
1476/// that's not of block-pointer type.
1477class ARCStrongByrefHelpers : public CodeGenModule::ByrefHelpers {
1478public:
1479  ARCStrongByrefHelpers(CharUnits alignment) : ByrefHelpers(alignment) {}
1480
1481  void emitCopy(CodeGenFunction &CGF, llvm::Value *destField,
1482                llvm::Value *srcField) {
1483    // Do a "move" by copying the value and then zeroing out the old
1484    // variable.
1485
1486    llvm::LoadInst *value = CGF.Builder.CreateLoad(srcField);
1487    value->setAlignment(Alignment.getQuantity());
1488
1489    llvm::Value *null =
1490      llvm::ConstantPointerNull::get(cast<llvm::PointerType>(value->getType()));
1491
1492    llvm::StoreInst *store = CGF.Builder.CreateStore(value, destField);
1493    store->setAlignment(Alignment.getQuantity());
1494
1495    store = CGF.Builder.CreateStore(null, srcField);
1496    store->setAlignment(Alignment.getQuantity());
1497  }
1498
1499  void emitDispose(CodeGenFunction &CGF, llvm::Value *field) {
1500    llvm::LoadInst *value = CGF.Builder.CreateLoad(field);
1501    value->setAlignment(Alignment.getQuantity());
1502
1503    CGF.EmitARCRelease(value, /*precise*/ false);
1504  }
1505
1506  void profileImpl(llvm::FoldingSetNodeID &id) const {
1507    // 1 is distinguishable from all pointers and byref flags
1508    id.AddInteger(1);
1509  }
1510};
1511
1512/// Emits the copy/dispose helpers for an ARC __block __strong
1513/// variable that's of block-pointer type.
1514class ARCStrongBlockByrefHelpers : public CodeGenModule::ByrefHelpers {
1515public:
1516  ARCStrongBlockByrefHelpers(CharUnits alignment) : ByrefHelpers(alignment) {}
1517
1518  void emitCopy(CodeGenFunction &CGF, llvm::Value *destField,
1519                llvm::Value *srcField) {
1520    // Do the copy with objc_retainBlock; that's all that
1521    // _Block_object_assign would do anyway, and we'd have to pass the
1522    // right arguments to make sure it doesn't get no-op'ed.
1523    llvm::LoadInst *oldValue = CGF.Builder.CreateLoad(srcField);
1524    oldValue->setAlignment(Alignment.getQuantity());
1525
1526    llvm::Value *copy = CGF.EmitARCRetainBlock(oldValue, /*mandatory*/ true);
1527
1528    llvm::StoreInst *store = CGF.Builder.CreateStore(copy, destField);
1529    store->setAlignment(Alignment.getQuantity());
1530  }
1531
1532  void emitDispose(CodeGenFunction &CGF, llvm::Value *field) {
1533    llvm::LoadInst *value = CGF.Builder.CreateLoad(field);
1534    value->setAlignment(Alignment.getQuantity());
1535
1536    CGF.EmitARCRelease(value, /*precise*/ false);
1537  }
1538
1539  void profileImpl(llvm::FoldingSetNodeID &id) const {
1540    // 2 is distinguishable from all pointers and byref flags
1541    id.AddInteger(2);
1542  }
1543};
1544
1545/// Emits the copy/dispose helpers for a __block variable with a
1546/// nontrivial copy constructor or destructor.
1547class CXXByrefHelpers : public CodeGenModule::ByrefHelpers {
1548  QualType VarType;
1549  const Expr *CopyExpr;
1550
1551public:
1552  CXXByrefHelpers(CharUnits alignment, QualType type,
1553                  const Expr *copyExpr)
1554    : ByrefHelpers(alignment), VarType(type), CopyExpr(copyExpr) {}
1555
1556  bool needsCopy() const { return CopyExpr != 0; }
1557  void emitCopy(CodeGenFunction &CGF, llvm::Value *destField,
1558                llvm::Value *srcField) {
1559    if (!CopyExpr) return;
1560    CGF.EmitSynthesizedCXXCopyCtor(destField, srcField, CopyExpr);
1561  }
1562
1563  void emitDispose(CodeGenFunction &CGF, llvm::Value *field) {
1564    EHScopeStack::stable_iterator cleanupDepth = CGF.EHStack.stable_begin();
1565    CGF.PushDestructorCleanup(VarType, field);
1566    CGF.PopCleanupBlocks(cleanupDepth);
1567  }
1568
1569  void profileImpl(llvm::FoldingSetNodeID &id) const {
1570    id.AddPointer(VarType.getCanonicalType().getAsOpaquePtr());
1571  }
1572};
1573} // end anonymous namespace
1574
1575static llvm::Constant *
1576generateByrefCopyHelper(CodeGenFunction &CGF,
1577                        llvm::StructType &byrefType,
1578                        CodeGenModule::ByrefHelpers &byrefInfo) {
1579  ASTContext &Context = CGF.getContext();
1580
1581  QualType R = Context.VoidTy;
1582
1583  FunctionArgList args;
1584  ImplicitParamDecl dst(0, SourceLocation(), 0, Context.VoidPtrTy);
1585  args.push_back(&dst);
1586
1587  ImplicitParamDecl src(0, SourceLocation(), 0, Context.VoidPtrTy);
1588  args.push_back(&src);
1589
1590  const CGFunctionInfo &FI =
1591    CGF.CGM.getTypes().arrangeFunctionDeclaration(R, args,
1592                                                  FunctionType::ExtInfo(),
1593                                                  /*variadic*/ false);
1594
1595  CodeGenTypes &Types = CGF.CGM.getTypes();
1596  llvm::FunctionType *LTy = Types.GetFunctionType(FI);
1597
1598  // FIXME: We'd like to put these into a mergable by content, with
1599  // internal linkage.
1600  llvm::Function *Fn =
1601    llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
1602                           "__Block_byref_object_copy_", &CGF.CGM.getModule());
1603
1604  IdentifierInfo *II
1605    = &Context.Idents.get("__Block_byref_object_copy_");
1606
1607  FunctionDecl *FD = FunctionDecl::Create(Context,
1608                                          Context.getTranslationUnitDecl(),
1609                                          SourceLocation(),
1610                                          SourceLocation(), II, R, 0,
1611                                          SC_Static,
1612                                          SC_None,
1613                                          false, false);
1614
1615  CGF.StartFunction(FD, R, Fn, FI, args, SourceLocation());
1616
1617  if (byrefInfo.needsCopy()) {
1618    llvm::Type *byrefPtrType = byrefType.getPointerTo(0);
1619
1620    // dst->x
1621    llvm::Value *destField = CGF.GetAddrOfLocalVar(&dst);
1622    destField = CGF.Builder.CreateLoad(destField);
1623    destField = CGF.Builder.CreateBitCast(destField, byrefPtrType);
1624    destField = CGF.Builder.CreateStructGEP(destField, 6, "x");
1625
1626    // src->x
1627    llvm::Value *srcField = CGF.GetAddrOfLocalVar(&src);
1628    srcField = CGF.Builder.CreateLoad(srcField);
1629    srcField = CGF.Builder.CreateBitCast(srcField, byrefPtrType);
1630    srcField = CGF.Builder.CreateStructGEP(srcField, 6, "x");
1631
1632    byrefInfo.emitCopy(CGF, destField, srcField);
1633  }
1634
1635  CGF.FinishFunction();
1636
1637  return llvm::ConstantExpr::getBitCast(Fn, CGF.Int8PtrTy);
1638}
1639
1640/// Build the copy helper for a __block variable.
1641static llvm::Constant *buildByrefCopyHelper(CodeGenModule &CGM,
1642                                            llvm::StructType &byrefType,
1643                                            CodeGenModule::ByrefHelpers &info) {
1644  CodeGenFunction CGF(CGM);
1645  return generateByrefCopyHelper(CGF, byrefType, info);
1646}
1647
1648/// Generate code for a __block variable's dispose helper.
1649static llvm::Constant *
1650generateByrefDisposeHelper(CodeGenFunction &CGF,
1651                           llvm::StructType &byrefType,
1652                           CodeGenModule::ByrefHelpers &byrefInfo) {
1653  ASTContext &Context = CGF.getContext();
1654  QualType R = Context.VoidTy;
1655
1656  FunctionArgList args;
1657  ImplicitParamDecl src(0, SourceLocation(), 0, Context.VoidPtrTy);
1658  args.push_back(&src);
1659
1660  const CGFunctionInfo &FI =
1661    CGF.CGM.getTypes().arrangeFunctionDeclaration(R, args,
1662                                                  FunctionType::ExtInfo(),
1663                                                  /*variadic*/ false);
1664
1665  CodeGenTypes &Types = CGF.CGM.getTypes();
1666  llvm::FunctionType *LTy = Types.GetFunctionType(FI);
1667
1668  // FIXME: We'd like to put these into a mergable by content, with
1669  // internal linkage.
1670  llvm::Function *Fn =
1671    llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
1672                           "__Block_byref_object_dispose_",
1673                           &CGF.CGM.getModule());
1674
1675  IdentifierInfo *II
1676    = &Context.Idents.get("__Block_byref_object_dispose_");
1677
1678  FunctionDecl *FD = FunctionDecl::Create(Context,
1679                                          Context.getTranslationUnitDecl(),
1680                                          SourceLocation(),
1681                                          SourceLocation(), II, R, 0,
1682                                          SC_Static,
1683                                          SC_None,
1684                                          false, false);
1685  CGF.StartFunction(FD, R, Fn, FI, args, SourceLocation());
1686
1687  if (byrefInfo.needsDispose()) {
1688    llvm::Value *V = CGF.GetAddrOfLocalVar(&src);
1689    V = CGF.Builder.CreateLoad(V);
1690    V = CGF.Builder.CreateBitCast(V, byrefType.getPointerTo(0));
1691    V = CGF.Builder.CreateStructGEP(V, 6, "x");
1692
1693    byrefInfo.emitDispose(CGF, V);
1694  }
1695
1696  CGF.FinishFunction();
1697
1698  return llvm::ConstantExpr::getBitCast(Fn, CGF.Int8PtrTy);
1699}
1700
1701/// Build the dispose helper for a __block variable.
1702static llvm::Constant *buildByrefDisposeHelper(CodeGenModule &CGM,
1703                                              llvm::StructType &byrefType,
1704                                            CodeGenModule::ByrefHelpers &info) {
1705  CodeGenFunction CGF(CGM);
1706  return generateByrefDisposeHelper(CGF, byrefType, info);
1707}
1708
1709///
1710template <class T> static T *buildByrefHelpers(CodeGenModule &CGM,
1711                                               llvm::StructType &byrefTy,
1712                                               T &byrefInfo) {
1713  // Increase the field's alignment to be at least pointer alignment,
1714  // since the layout of the byref struct will guarantee at least that.
1715  byrefInfo.Alignment = std::max(byrefInfo.Alignment,
1716                              CharUnits::fromQuantity(CGM.PointerAlignInBytes));
1717
1718  llvm::FoldingSetNodeID id;
1719  byrefInfo.Profile(id);
1720
1721  void *insertPos;
1722  CodeGenModule::ByrefHelpers *node
1723    = CGM.ByrefHelpersCache.FindNodeOrInsertPos(id, insertPos);
1724  if (node) return static_cast<T*>(node);
1725
1726  byrefInfo.CopyHelper = buildByrefCopyHelper(CGM, byrefTy, byrefInfo);
1727  byrefInfo.DisposeHelper = buildByrefDisposeHelper(CGM, byrefTy, byrefInfo);
1728
1729  T *copy = new (CGM.getContext()) T(byrefInfo);
1730  CGM.ByrefHelpersCache.InsertNode(copy, insertPos);
1731  return copy;
1732}
1733
1734CodeGenModule::ByrefHelpers *
1735CodeGenFunction::buildByrefHelpers(llvm::StructType &byrefType,
1736                                   const AutoVarEmission &emission) {
1737  const VarDecl &var = *emission.Variable;
1738  QualType type = var.getType();
1739
1740  if (const CXXRecordDecl *record = type->getAsCXXRecordDecl()) {
1741    const Expr *copyExpr = CGM.getContext().getBlockVarCopyInits(&var);
1742    if (!copyExpr && record->hasTrivialDestructor()) return 0;
1743
1744    CXXByrefHelpers byrefInfo(emission.Alignment, type, copyExpr);
1745    return ::buildByrefHelpers(CGM, byrefType, byrefInfo);
1746  }
1747
1748  // Otherwise, if we don't have a retainable type, there's nothing to do.
1749  // that the runtime does extra copies.
1750  if (!type->isObjCRetainableType()) return 0;
1751
1752  Qualifiers qs = type.getQualifiers();
1753
1754  // If we have lifetime, that dominates.
1755  if (Qualifiers::ObjCLifetime lifetime = qs.getObjCLifetime()) {
1756    assert(getLangOpts().ObjCAutoRefCount);
1757
1758    switch (lifetime) {
1759    case Qualifiers::OCL_None: llvm_unreachable("impossible");
1760
1761    // These are just bits as far as the runtime is concerned.
1762    case Qualifiers::OCL_ExplicitNone:
1763    case Qualifiers::OCL_Autoreleasing:
1764      return 0;
1765
1766    // Tell the runtime that this is ARC __weak, called by the
1767    // byref routines.
1768    case Qualifiers::OCL_Weak: {
1769      ARCWeakByrefHelpers byrefInfo(emission.Alignment);
1770      return ::buildByrefHelpers(CGM, byrefType, byrefInfo);
1771    }
1772
1773    // ARC __strong __block variables need to be retained.
1774    case Qualifiers::OCL_Strong:
1775      // Block pointers need to be copied, and there's no direct
1776      // transfer possible.
1777      if (type->isBlockPointerType()) {
1778        ARCStrongBlockByrefHelpers byrefInfo(emission.Alignment);
1779        return ::buildByrefHelpers(CGM, byrefType, byrefInfo);
1780
1781      // Otherwise, we transfer ownership of the retain from the stack
1782      // to the heap.
1783      } else {
1784        ARCStrongByrefHelpers byrefInfo(emission.Alignment);
1785        return ::buildByrefHelpers(CGM, byrefType, byrefInfo);
1786      }
1787    }
1788    llvm_unreachable("fell out of lifetime switch!");
1789  }
1790
1791  BlockFieldFlags flags;
1792  if (type->isBlockPointerType()) {
1793    flags |= BLOCK_FIELD_IS_BLOCK;
1794  } else if (CGM.getContext().isObjCNSObjectType(type) ||
1795             type->isObjCObjectPointerType()) {
1796    flags |= BLOCK_FIELD_IS_OBJECT;
1797  } else {
1798    return 0;
1799  }
1800
1801  if (type.isObjCGCWeak())
1802    flags |= BLOCK_FIELD_IS_WEAK;
1803
1804  ObjectByrefHelpers byrefInfo(emission.Alignment, flags);
1805  return ::buildByrefHelpers(CGM, byrefType, byrefInfo);
1806}
1807
1808unsigned CodeGenFunction::getByRefValueLLVMField(const ValueDecl *VD) const {
1809  assert(ByRefValueInfo.count(VD) && "Did not find value!");
1810
1811  return ByRefValueInfo.find(VD)->second.second;
1812}
1813
1814llvm::Value *CodeGenFunction::BuildBlockByrefAddress(llvm::Value *BaseAddr,
1815                                                     const VarDecl *V) {
1816  llvm::Value *Loc = Builder.CreateStructGEP(BaseAddr, 1, "forwarding");
1817  Loc = Builder.CreateLoad(Loc);
1818  Loc = Builder.CreateStructGEP(Loc, getByRefValueLLVMField(V),
1819                                V->getNameAsString());
1820  return Loc;
1821}
1822
1823/// BuildByRefType - This routine changes a __block variable declared as T x
1824///   into:
1825///
1826///      struct {
1827///        void *__isa;
1828///        void *__forwarding;
1829///        int32_t __flags;
1830///        int32_t __size;
1831///        void *__copy_helper;       // only if needed
1832///        void *__destroy_helper;    // only if needed
1833///        char padding[X];           // only if needed
1834///        T x;
1835///      } x
1836///
1837llvm::Type *CodeGenFunction::BuildByRefType(const VarDecl *D) {
1838  std::pair<llvm::Type *, unsigned> &Info = ByRefValueInfo[D];
1839  if (Info.first)
1840    return Info.first;
1841
1842  QualType Ty = D->getType();
1843
1844  SmallVector<llvm::Type *, 8> types;
1845
1846  llvm::StructType *ByRefType =
1847    llvm::StructType::create(getLLVMContext(),
1848                             "struct.__block_byref_" + D->getNameAsString());
1849
1850  // void *__isa;
1851  types.push_back(Int8PtrTy);
1852
1853  // void *__forwarding;
1854  types.push_back(llvm::PointerType::getUnqual(ByRefType));
1855
1856  // int32_t __flags;
1857  types.push_back(Int32Ty);
1858
1859  // int32_t __size;
1860  types.push_back(Int32Ty);
1861
1862  bool HasCopyAndDispose =
1863       (Ty->isObjCRetainableType()) || getContext().getBlockVarCopyInits(D);
1864  if (HasCopyAndDispose) {
1865    /// void *__copy_helper;
1866    types.push_back(Int8PtrTy);
1867
1868    /// void *__destroy_helper;
1869    types.push_back(Int8PtrTy);
1870  }
1871
1872  bool Packed = false;
1873  CharUnits Align = getContext().getDeclAlign(D);
1874  if (Align > getContext().toCharUnitsFromBits(Target.getPointerAlign(0))) {
1875    // We have to insert padding.
1876
1877    // The struct above has 2 32-bit integers.
1878    unsigned CurrentOffsetInBytes = 4 * 2;
1879
1880    // And either 2 or 4 pointers.
1881    CurrentOffsetInBytes += (HasCopyAndDispose ? 4 : 2) *
1882      CGM.getTargetData().getTypeAllocSize(Int8PtrTy);
1883
1884    // Align the offset.
1885    unsigned AlignedOffsetInBytes =
1886      llvm::RoundUpToAlignment(CurrentOffsetInBytes, Align.getQuantity());
1887
1888    unsigned NumPaddingBytes = AlignedOffsetInBytes - CurrentOffsetInBytes;
1889    if (NumPaddingBytes > 0) {
1890      llvm::Type *Ty = Int8Ty;
1891      // FIXME: We need a sema error for alignment larger than the minimum of
1892      // the maximal stack alignment and the alignment of malloc on the system.
1893      if (NumPaddingBytes > 1)
1894        Ty = llvm::ArrayType::get(Ty, NumPaddingBytes);
1895
1896      types.push_back(Ty);
1897
1898      // We want a packed struct.
1899      Packed = true;
1900    }
1901  }
1902
1903  // T x;
1904  types.push_back(ConvertTypeForMem(Ty));
1905
1906  ByRefType->setBody(types, Packed);
1907
1908  Info.first = ByRefType;
1909
1910  Info.second = types.size() - 1;
1911
1912  return Info.first;
1913}
1914
1915/// Initialize the structural components of a __block variable, i.e.
1916/// everything but the actual object.
1917void CodeGenFunction::emitByrefStructureInit(const AutoVarEmission &emission) {
1918  // Find the address of the local.
1919  llvm::Value *addr = emission.Address;
1920
1921  // That's an alloca of the byref structure type.
1922  llvm::StructType *byrefType = cast<llvm::StructType>(
1923                 cast<llvm::PointerType>(addr->getType())->getElementType());
1924
1925  // Build the byref helpers if necessary.  This is null if we don't need any.
1926  CodeGenModule::ByrefHelpers *helpers =
1927    buildByrefHelpers(*byrefType, emission);
1928
1929  const VarDecl &D = *emission.Variable;
1930  QualType type = D.getType();
1931
1932  llvm::Value *V;
1933
1934  // Initialize the 'isa', which is just 0 or 1.
1935  int isa = 0;
1936  if (type.isObjCGCWeak())
1937    isa = 1;
1938  V = Builder.CreateIntToPtr(Builder.getInt32(isa), Int8PtrTy, "isa");
1939  Builder.CreateStore(V, Builder.CreateStructGEP(addr, 0, "byref.isa"));
1940
1941  // Store the address of the variable into its own forwarding pointer.
1942  Builder.CreateStore(addr,
1943                      Builder.CreateStructGEP(addr, 1, "byref.forwarding"));
1944
1945  // Blocks ABI:
1946  //   c) the flags field is set to either 0 if no helper functions are
1947  //      needed or BLOCK_HAS_COPY_DISPOSE if they are,
1948  BlockFlags flags;
1949  if (helpers) flags |= BLOCK_HAS_COPY_DISPOSE;
1950  Builder.CreateStore(llvm::ConstantInt::get(IntTy, flags.getBitMask()),
1951                      Builder.CreateStructGEP(addr, 2, "byref.flags"));
1952
1953  CharUnits byrefSize = CGM.GetTargetTypeStoreSize(byrefType);
1954  V = llvm::ConstantInt::get(IntTy, byrefSize.getQuantity());
1955  Builder.CreateStore(V, Builder.CreateStructGEP(addr, 3, "byref.size"));
1956
1957  if (helpers) {
1958    llvm::Value *copy_helper = Builder.CreateStructGEP(addr, 4);
1959    Builder.CreateStore(helpers->CopyHelper, copy_helper);
1960
1961    llvm::Value *destroy_helper = Builder.CreateStructGEP(addr, 5);
1962    Builder.CreateStore(helpers->DisposeHelper, destroy_helper);
1963  }
1964}
1965
1966void CodeGenFunction::BuildBlockRelease(llvm::Value *V, BlockFieldFlags flags) {
1967  llvm::Value *F = CGM.getBlockObjectDispose();
1968  llvm::Value *N;
1969  V = Builder.CreateBitCast(V, Int8PtrTy);
1970  N = llvm::ConstantInt::get(Int32Ty, flags.getBitMask());
1971  Builder.CreateCall2(F, V, N);
1972}
1973
1974namespace {
1975  struct CallBlockRelease : EHScopeStack::Cleanup {
1976    llvm::Value *Addr;
1977    CallBlockRelease(llvm::Value *Addr) : Addr(Addr) {}
1978
1979    void Emit(CodeGenFunction &CGF, Flags flags) {
1980      // Should we be passing FIELD_IS_WEAK here?
1981      CGF.BuildBlockRelease(Addr, BLOCK_FIELD_IS_BYREF);
1982    }
1983  };
1984}
1985
1986/// Enter a cleanup to destroy a __block variable.  Note that this
1987/// cleanup should be a no-op if the variable hasn't left the stack
1988/// yet; if a cleanup is required for the variable itself, that needs
1989/// to be done externally.
1990void CodeGenFunction::enterByrefCleanup(const AutoVarEmission &emission) {
1991  // We don't enter this cleanup if we're in pure-GC mode.
1992  if (CGM.getLangOpts().getGC() == LangOptions::GCOnly)
1993    return;
1994
1995  EHStack.pushCleanup<CallBlockRelease>(NormalAndEHCleanup, emission.Address);
1996}
1997
1998/// Adjust the declaration of something from the blocks API.
1999static void configureBlocksRuntimeObject(CodeGenModule &CGM,
2000                                         llvm::Constant *C) {
2001  if (!CGM.getLangOpts().BlocksRuntimeOptional) return;
2002
2003  llvm::GlobalValue *GV = cast<llvm::GlobalValue>(C->stripPointerCasts());
2004  if (GV->isDeclaration() &&
2005      GV->getLinkage() == llvm::GlobalValue::ExternalLinkage)
2006    GV->setLinkage(llvm::GlobalValue::ExternalWeakLinkage);
2007}
2008
2009llvm::Constant *CodeGenModule::getBlockObjectDispose() {
2010  if (BlockObjectDispose)
2011    return BlockObjectDispose;
2012
2013  llvm::Type *args[] = { Int8PtrTy, Int32Ty };
2014  llvm::FunctionType *fty
2015    = llvm::FunctionType::get(VoidTy, args, false);
2016  BlockObjectDispose = CreateRuntimeFunction(fty, "_Block_object_dispose");
2017  configureBlocksRuntimeObject(*this, BlockObjectDispose);
2018  return BlockObjectDispose;
2019}
2020
2021llvm::Constant *CodeGenModule::getBlockObjectAssign() {
2022  if (BlockObjectAssign)
2023    return BlockObjectAssign;
2024
2025  llvm::Type *args[] = { Int8PtrTy, Int8PtrTy, Int32Ty };
2026  llvm::FunctionType *fty
2027    = llvm::FunctionType::get(VoidTy, args, false);
2028  BlockObjectAssign = CreateRuntimeFunction(fty, "_Block_object_assign");
2029  configureBlocksRuntimeObject(*this, BlockObjectAssign);
2030  return BlockObjectAssign;
2031}
2032
2033llvm::Constant *CodeGenModule::getNSConcreteGlobalBlock() {
2034  if (NSConcreteGlobalBlock)
2035    return NSConcreteGlobalBlock;
2036
2037  NSConcreteGlobalBlock = GetOrCreateLLVMGlobal("_NSConcreteGlobalBlock",
2038                                                Int8PtrTy->getPointerTo(), 0);
2039  configureBlocksRuntimeObject(*this, NSConcreteGlobalBlock);
2040  return NSConcreteGlobalBlock;
2041}
2042
2043llvm::Constant *CodeGenModule::getNSConcreteStackBlock() {
2044  if (NSConcreteStackBlock)
2045    return NSConcreteStackBlock;
2046
2047  NSConcreteStackBlock = GetOrCreateLLVMGlobal("_NSConcreteStackBlock",
2048                                               Int8PtrTy->getPointerTo(), 0);
2049  configureBlocksRuntimeObject(*this, NSConcreteStackBlock);
2050  return NSConcreteStackBlock;
2051}
2052