objective-C blocks: Provide layout map for byref

variables captured in a block. // rdar://12184410



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@167931 91177308-0d34-0410-b5e6-96231b3b80d8

7 files changed, 235 insertions, 80 deletions

diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index 80ce66a017..7b61c25b1d 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -4368,6 +4368,29 @@ bool ASTContext::BlockRequiresCopying(QualType Ty) const {
   return false;
 }
 
+bool ASTContext::getByrefLifetime(QualType Ty,
+                              Qualifiers::ObjCLifetime &LifeTime,
+                              bool &HasByrefExtendedLayout) const {
+  
+  if (!getLangOpts().ObjC1 ||
+      getLangOpts().getGC() != LangOptions::NonGC)
+    return false;
+  
+  HasByrefExtendedLayout = false;
+  if (Ty->isAggregateType()) {
+    HasByrefExtendedLayout = true;
+    LifeTime = Qualifiers::OCL_None;
+  }
+  else if (getLangOpts().ObjCAutoRefCount)
+    LifeTime = Ty.getObjCLifetime();
+  // MRR.
+  else if (Ty->isObjCObjectPointerType() || Ty->isBlockPointerType())
+    LifeTime = Qualifiers::OCL_ExplicitNone;
+  else
+    LifeTime = Qualifiers::OCL_None;
+  return true;
+}
+
 QualType
 ASTContext::BuildByRefType(StringRef DeclName, QualType Ty) const {
   //  type = struct __Block_byref_1_X {
@@ -4377,10 +4400,13 @@ ASTContext::BuildByRefType(StringRef DeclName, QualType Ty) const {
   //    unsigned int __size;
   //    void *__copy_helper;            // as needed
   //    void *__destroy_help            // as needed
+  //    void *__byref_variable_layout;    // Extended layout info. for byref variable as needed
   //    int X;
   //  } *
 
   bool HasCopyAndDispose = BlockRequiresCopying(Ty);
+  bool HasByrefExtendedLayout;
+  Qualifiers::ObjCLifetime Lifetime;
 
   // FIXME: Move up
   SmallString<36> Name;
@@ -4398,6 +4424,7 @@ ASTContext::BuildByRefType(StringRef DeclName, QualType Ty) const {
     Int32Ty,
     getPointerType(VoidPtrTy),
     getPointerType(VoidPtrTy),
+    getPointerType(VoidPtrTy),
     Ty
   };
 
@@ -4408,12 +4435,15 @@ ASTContext::BuildByRefType(StringRef DeclName, QualType Ty) const {
     "__size",
     "__copy_helper",
     "__destroy_helper",
+    "__byref_variable_layout",
     DeclName,
   };
-
-  for (size_t i = 0; i < 7; ++i) {
+  bool ByrefKnownLifetime = getByrefLifetime(Ty, Lifetime, HasByrefExtendedLayout);
+  for (size_t i = 0; i < 8; ++i) {
     if (!HasCopyAndDispose && i >=4 && i <= 5)
       continue;
+    if ((!ByrefKnownLifetime || !HasByrefExtendedLayout) && i == 6)
+      continue;
     FieldDecl *Field = FieldDecl::Create(*this, T, SourceLocation(),
                                          SourceLocation(),
                                          &Idents.get(FieldNames[i]),
diff --git a/lib/CodeGen/CGBlocks.cpp b/lib/CodeGen/CGBlocks.cpp
index 6742f36cf8..33f6eebd67 100644
--- a/lib/CodeGen/CGBlocks.cpp
+++ b/lib/CodeGen/CGBlocks.cpp
@@ -1892,6 +1892,7 @@ llvm::Value *CodeGenFunction::BuildBlockByrefAddress(llvm::Value *BaseAddr,
 ///        int32_t __size;
 ///        void *__copy_helper;       // only if needed
 ///        void *__destroy_helper;    // only if needed
+///        void *__byref_variable_layout;// only if needed
 ///        char padding[X];           // only if needed
 ///        T x;
 ///      } x
@@ -1930,6 +1931,12 @@ llvm::Type *CodeGenFunction::BuildByRefType(const VarDecl *D) {
     /// void *__destroy_helper;
     types.push_back(Int8PtrTy);
   }
+  bool HasByrefExtendedLayout = false;
+  Qualifiers::ObjCLifetime Lifetime;
+  if (getContext().getByrefLifetime(Ty, Lifetime, HasByrefExtendedLayout) &&
+      HasByrefExtendedLayout)
+    /// void *__byref_variable_layout;
+    types.push_back(Int8PtrTy);
 
   bool Packed = false;
   CharUnits Align = getContext().getDeclAlign(D);
@@ -1939,9 +1946,14 @@ llvm::Type *CodeGenFunction::BuildByRefType(const VarDecl *D) {
     // The struct above has 2 32-bit integers.
     unsigned CurrentOffsetInBytes = 4 * 2;
     
-    // And either 2 or 4 pointers.
-    CurrentOffsetInBytes += (HasCopyAndDispose ? 4 : 2) *
-      CGM.getDataLayout().getTypeAllocSize(Int8PtrTy);
+    // And either 2, 3, 4 or 5 pointers.
+    unsigned noPointers = 2;
+    if (HasCopyAndDispose)
+      noPointers += 2;
+    if (HasByrefExtendedLayout)
+      noPointers += 1;
+    
+    CurrentOffsetInBytes += noPointers * CGM.getDataLayout().getTypeAllocSize(Int8PtrTy);
     
     // Align the offset.
     unsigned AlignedOffsetInBytes = 
@@ -1991,6 +2003,11 @@ void CodeGenFunction::emitByrefStructureInit(const AutoVarEmission &emission) {
   const VarDecl &D = *emission.Variable;
   QualType type = D.getType();
 
+  bool HasByrefExtendedLayout;
+  Qualifiers::ObjCLifetime ByrefLifetime;
+  bool ByRefHasLifetime =
+    getContext().getByrefLifetime(type, ByrefLifetime, HasByrefExtendedLayout);
+  
   llvm::Value *V;
 
   // Initialize the 'isa', which is just 0 or 1.
@@ -2006,9 +2023,49 @@ void CodeGenFunction::emitByrefStructureInit(const AutoVarEmission &emission) {
 
   // Blocks ABI:
   //   c) the flags field is set to either 0 if no helper functions are
-  //      needed or BLOCK_HAS_COPY_DISPOSE if they are,
+  //      needed or BLOCK_BYREF_HAS_COPY_DISPOSE if they are,
   BlockFlags flags;
-  if (helpers) flags |= BLOCK_HAS_COPY_DISPOSE;
+  if (helpers) flags |= BLOCK_BYREF_HAS_COPY_DISPOSE;
+  if (ByRefHasLifetime) {
+    if (HasByrefExtendedLayout) flags |= BLOCK_BYREF_LAYOUT_EXTENDED;
+      else switch (ByrefLifetime) {
+        case Qualifiers::OCL_Strong:
+          flags |= BLOCK_BYREF_LAYOUT_STRONG;
+          break;
+        case Qualifiers::OCL_Weak:
+          flags |= BLOCK_BYREF_LAYOUT_WEAK;
+          break;
+        case Qualifiers::OCL_ExplicitNone:
+          flags |= BLOCK_BYREF_LAYOUT_UNRETAINED;
+          break;
+        case Qualifiers::OCL_None:
+          if (!type->isObjCObjectPointerType() && !type->isBlockPointerType())
+            flags |= BLOCK_BYREF_LAYOUT_NON_OBJECT;
+          break;
+        default:
+          break;
+      }
+    if (CGM.getLangOpts().ObjCGCBitmapPrint) {
+      printf("\n Inline flag for BYREF variable layout (%d):", flags.getBitMask());
+      if (flags & BLOCK_BYREF_HAS_COPY_DISPOSE)
+        printf(" BLOCK_BYREF_HAS_COPY_DISPOSE");
+      if (flags & BLOCK_BYREF_LAYOUT_MASK) {
+        BlockFlags ThisFlag(flags.getBitMask() & BLOCK_BYREF_LAYOUT_MASK);
+        if (ThisFlag ==  BLOCK_BYREF_LAYOUT_EXTENDED)
+          printf(" BLOCK_BYREF_LAYOUT_EXTENDED");
+        if (ThisFlag ==  BLOCK_BYREF_LAYOUT_STRONG)
+          printf(" BLOCK_BYREF_LAYOUT_STRONG");
+        if (ThisFlag == BLOCK_BYREF_LAYOUT_WEAK)
+          printf(" BLOCK_BYREF_LAYOUT_WEAK");
+        if (ThisFlag == BLOCK_BYREF_LAYOUT_UNRETAINED)
+          printf(" BLOCK_BYREF_LAYOUT_UNRETAINED");
+        if (ThisFlag == BLOCK_BYREF_LAYOUT_NON_OBJECT)
+          printf(" BLOCK_BYREF_LAYOUT_NON_OBJECT");
+      }
+      printf("\n");
+    }
+  }
+  
   Builder.CreateStore(llvm::ConstantInt::get(IntTy, flags.getBitMask()),
                       Builder.CreateStructGEP(addr, 2, "byref.flags"));
 
@@ -2023,6 +2080,16 @@ void CodeGenFunction::emitByrefStructureInit(const AutoVarEmission &emission) {
     llvm::Value *destroy_helper = Builder.CreateStructGEP(addr, 5);
     Builder.CreateStore(helpers->DisposeHelper, destroy_helper);
   }
+  if (ByRefHasLifetime && HasByrefExtendedLayout) {
+    llvm::Constant* ByrefLayoutInfo = CGM.getObjCRuntime().BuildByrefLayout(CGM, type);
+    llvm::Value *ByrefInfoAddr = Builder.CreateStructGEP(addr, helpers ? 6 : 4,
+                                                         "byref.layout");
+    // cast destination to pointer to source type.
+    llvm::Type *DesTy = ByrefLayoutInfo->getType();
+    DesTy = DesTy->getPointerTo();
+    llvm::Value *BC = Builder.CreatePointerCast(ByrefInfoAddr, DesTy);
+    Builder.CreateStore(ByrefLayoutInfo, BC);
+  }
 }
 
 void CodeGenFunction::BuildBlockRelease(llvm::Value *V, BlockFieldFlags flags) {
diff --git a/lib/CodeGen/CGBlocks.h b/lib/CodeGen/CGBlocks.h
index f85701af78..d54ba27692 100644
--- a/lib/CodeGen/CGBlocks.h
+++ b/lib/CodeGen/CGBlocks.h
@@ -69,11 +69,12 @@ enum BlockLiteralFlags {
 class BlockFlags {
   uint32_t flags;
 
-  BlockFlags(uint32_t flags) : flags(flags) {}
 public:
+  BlockFlags(uint32_t flags) : flags(flags) {}
   BlockFlags() : flags(0) {}
   BlockFlags(BlockLiteralFlags flag) : flags(flag) {}
-
+  BlockFlags(BlockByrefFlags flag) : flags(flag) {}
+  
   uint32_t getBitMask() const { return flags; }
   bool empty() const { return flags == 0; }
 
@@ -87,6 +88,9 @@ public:
   friend bool operator&(BlockFlags l, BlockFlags r) {
     return (l.flags & r.flags);
   }
+  bool operator==(BlockFlags r) {
+    return (flags == r.flags);
+  }
 };
 inline BlockFlags operator|(BlockLiteralFlags l, BlockLiteralFlags r) {
   return BlockFlags(l) | BlockFlags(r);
diff --git a/lib/CodeGen/CGDebugInfo.cpp b/lib/CodeGen/CGDebugInfo.cpp
index 80fa09be74..1d9f8ed146 100644
--- a/lib/CodeGen/CGDebugInfo.cpp
+++ b/lib/CodeGen/CGDebugInfo.cpp
@@ -2256,6 +2256,12 @@ llvm::DIType CGDebugInfo::EmitTypeForVarWithBlocksAttr(const ValueDecl *VD,
     EltTys.push_back(CreateMemberType(Unit, FType, "__destroy_helper",
                                       &FieldOffset));
   }
+  bool HasByrefExtendedLayout;
+  Qualifiers::ObjCLifetime Lifetime;
+  if (CGM.getContext().getByrefLifetime(Type, Lifetime, HasByrefExtendedLayout) &&
+      HasByrefExtendedLayout)
+    EltTys.push_back(CreateMemberType(Unit, FType, "__byref_variable_layout",
+                                      &FieldOffset));
   
   CharUnits Align = CGM.getContext().getDeclAlign(VD);
   if (Align > CGM.getContext().toCharUnitsFromBits(
diff --git a/lib/CodeGen/CGObjCGNU.cpp b/lib/CodeGen/CGObjCGNU.cpp
index 68d234dde6..df73abc060 100644
--- a/lib/CodeGen/CGObjCGNU.cpp
+++ b/lib/CodeGen/CGObjCGNU.cpp
@@ -537,6 +537,12 @@ public:
                                              const CGBlockInfo &blockInfo) {
     return NULLPtr;
   }
+  
+  virtual llvm::Constant *BuildByrefLayout(CodeGenModule &CGM,
+                                           QualType T) {
+    return NULLPtr;
+  }
+  
   virtual llvm::GlobalVariable *GetClassGlobal(const std::string &Name) {
     return 0;
   }
diff --git a/lib/CodeGen/CGObjCMac.cpp b/lib/CodeGen/CGObjCMac.cpp
index 2203f01828..611fb384bd 100644
--- a/lib/CodeGen/CGObjCMac.cpp
+++ b/lib/CodeGen/CGObjCMac.cpp
@@ -943,7 +943,7 @@ protected:
                            unsigned int BytePos, bool ForStrongLayout,
                            bool &HasUnion);
   
-  Qualifiers::ObjCLifetime getBlockCaptureLifetime(QualType QT);
+  Qualifiers::ObjCLifetime getBlockCaptureLifetime(QualType QT, bool ByrefLayout);
   
   void UpdateRunSkipBlockVars(bool IsByref,
                               Qualifiers::ObjCLifetime LifeTime,
@@ -951,15 +951,19 @@ protected:
                               CharUnits FieldSize);
   
   void BuildRCBlockVarRecordLayout(const RecordType *RT,
-                                   CharUnits BytePos, bool &HasUnion);
+                                   CharUnits BytePos, bool &HasUnion,
+                                   bool ByrefLayout=false);
   
   void BuildRCRecordLayout(const llvm::StructLayout *RecLayout,
                            const RecordDecl *RD,
                            ArrayRef<const FieldDecl*> RecFields,
-                           CharUnits BytePos, bool &HasUnion);
+                           CharUnits BytePos, bool &HasUnion,
+                           bool ByrefLayout);
   
   uint64_t InlineLayoutInstruction(SmallVectorImpl<unsigned char> &Layout);
   
+  llvm::Constant *getBitmapBlockLayout(bool ComputeByrefLayout);
+  
 
   /// GetIvarLayoutName - Returns a unique constant for the given
   /// ivar layout bitmap.
@@ -1053,6 +1057,8 @@ public:
   virtual llvm::Constant *BuildRCBlockLayout(CodeGen::CodeGenModule &CGM,
                                              const CGBlockInfo &blockInfo);
   
+  virtual llvm::Constant *BuildByrefLayout(CodeGen::CodeGenModule &CGM,
+                                           QualType T);
 };
 
 class CGObjCMac : public CGObjCCommonMac {
@@ -1968,13 +1974,14 @@ llvm::Constant *CGObjCCommonMac::BuildGCBlockLayout(CodeGenModule &CGM,
 /// getBlockCaptureLifetime - This routine returns life time of the captured
 /// block variable for the purpose of block layout meta-data generation. FQT is
 /// the type of the variable captured in the block.
-Qualifiers::ObjCLifetime CGObjCCommonMac::getBlockCaptureLifetime(QualType FQT) {
+Qualifiers::ObjCLifetime CGObjCCommonMac::getBlockCaptureLifetime(QualType FQT,
+                                                                  bool ByrefLayout) {
   if (CGM.getLangOpts().ObjCAutoRefCount)
     return FQT.getObjCLifetime();
   
   // MRR.
   if (FQT->isObjCObjectPointerType() || FQT->isBlockPointerType())
-    return Qualifiers::OCL_ExplicitNone;
+    return ByrefLayout ? Qualifiers::OCL_ExplicitNone : Qualifiers::OCL_Strong;
   
   return Qualifiers::OCL_None;
 }
@@ -2005,7 +2012,8 @@ void CGObjCCommonMac::UpdateRunSkipBlockVars(bool IsByref,
 void CGObjCCommonMac::BuildRCRecordLayout(const llvm::StructLayout *RecLayout,
                                           const RecordDecl *RD,
                                           ArrayRef<const FieldDecl*> RecFields,
-                                          CharUnits BytePos, bool &HasUnion) {
+                                          CharUnits BytePos, bool &HasUnion,
+                                          bool ByrefLayout) {
   bool IsUnion = (RD && RD->isUnion());
   CharUnits MaxUnionSize = CharUnits::Zero();
   const FieldDecl *MaxField = 0;
@@ -2088,7 +2096,7 @@ void CGObjCCommonMac::BuildRCRecordLayout(const llvm::StructLayout *RecLayout,
       }
     } else {
       UpdateRunSkipBlockVars(false,
-                             getBlockCaptureLifetime(FQT),
+                             getBlockCaptureLifetime(FQT, ByrefLayout),
                              BytePos + FieldOffset,
                              FieldSize);
     }
@@ -2104,7 +2112,8 @@ void CGObjCCommonMac::BuildRCRecordLayout(const llvm::StructLayout *RecLayout,
       CharUnits Size = CharUnits::fromQuantity(UnsSize);
       Size += LastBitfieldOrUnnamedOffset;
       UpdateRunSkipBlockVars(false,
-                             getBlockCaptureLifetime(LastFieldBitfieldOrUnnamed->getType()),
+                             getBlockCaptureLifetime(LastFieldBitfieldOrUnnamed->getType(),
+                                                     ByrefLayout),
                              BytePos + LastBitfieldOrUnnamedOffset,
                              Size);
     } else {
@@ -2113,7 +2122,8 @@ void CGObjCCommonMac::BuildRCRecordLayout(const llvm::StructLayout *RecLayout,
       CharUnits FieldSize
         = CGM.getContext().getTypeSizeInChars(LastFieldBitfieldOrUnnamed->getType());
       UpdateRunSkipBlockVars(false,
-                             getBlockCaptureLifetime(LastFieldBitfieldOrUnnamed->getType()),
+                             getBlockCaptureLifetime(LastFieldBitfieldOrUnnamed->getType(),
+                                                     ByrefLayout),
                              BytePos + LastBitfieldOrUnnamedOffset,
                              FieldSize);
     }
@@ -2121,14 +2131,15 @@ void CGObjCCommonMac::BuildRCRecordLayout(const llvm::StructLayout *RecLayout,
   
   if (MaxField)
     UpdateRunSkipBlockVars(false,
-                           getBlockCaptureLifetime(MaxField->getType()),
+                           getBlockCaptureLifetime(MaxField->getType(), ByrefLayout),
                            BytePos + MaxFieldOffset,
                            MaxUnionSize);
 }
 
 void CGObjCCommonMac::BuildRCBlockVarRecordLayout(const RecordType *RT,
                                                   CharUnits BytePos,
-                                                  bool &HasUnion) {
+                                                  bool &HasUnion,
+                                                  bool ByrefLayout) {
   const RecordDecl *RD = RT->getDecl();
   SmallVector<const FieldDecl*, 16> Fields;
   for (RecordDecl::field_iterator i = RD->field_begin(),
@@ -2138,7 +2149,7 @@ void CGObjCCommonMac::BuildRCBlockVarRecordLayout(const RecordType *RT,
   const llvm::StructLayout *RecLayout =
     CGM.getDataLayout().getStructLayout(cast<llvm::StructType>(Ty));
   
-  BuildRCRecordLayout(RecLayout, RD, Fields, BytePos, HasUnion);
+  BuildRCRecordLayout(RecLayout, RD, Fields, BytePos, HasUnion, ByrefLayout);
 }
 
 /// InlineLayoutInstruction - This routine produce an inline instruction for the
@@ -2247,64 +2258,19 @@ uint64_t CGObjCCommonMac::InlineLayoutInstruction(
   return Result;
 }
 
-llvm::Constant *CGObjCCommonMac::BuildRCBlockLayout(CodeGenModule &CGM,
-                                                    const CGBlockInfo &blockInfo) {
-  assert(CGM.getLangOpts().getGC() == LangOptions::NonGC);
-  
+llvm::Constant *CGObjCCommonMac::getBitmapBlockLayout(bool ComputeByrefLayout) {
   llvm::Constant *nullPtr = llvm::Constant::getNullValue(CGM.Int8PtrTy);
-  
-  RunSkipBlockVars.clear();
-  bool hasUnion = false;
-  
+  if (RunSkipBlockVars.empty())
+    return nullPtr;
   unsigned WordSizeInBits = CGM.getContext().getTargetInfo().getPointerWidth(0);
   unsigned ByteSizeInBits = CGM.getContext().getTargetInfo().getCharWidth();
   unsigned WordSizeInBytes = WordSizeInBits/ByteSizeInBits;
   
-  const BlockDecl *blockDecl = blockInfo.getBlockDecl();
-  
-  // Calculate the basic layout of the block structure.
-  const llvm::StructLayout *layout =
-  CGM.getDataLayout().getStructLayout(blockInfo.StructureType);
-  
-  // Ignore the optional 'this' capture: C++ objects are not assumed
-  // to be GC'ed.
-  
-  // Walk the captured variables.
-  for (BlockDecl::capture_const_iterator ci = blockDecl->capture_begin(),
-       ce = blockDecl->capture_end(); ci != ce; ++ci) {
-    const VarDecl *variable = ci->getVariable();
-    QualType type = variable->getType();
-    
-    const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
-    
-    // Ignore constant captures.
-    if (capture.isConstant()) continue;
-    
-    CharUnits fieldOffset =
-       CharUnits::fromQuantity(layout->getElementOffset(capture.getIndex()));
-    
-    assert(!type->isArrayType() && "array variable should not be caught");
-    if (const RecordType *record = type->getAs<RecordType>()) {
-      BuildRCBlockVarRecordLayout(record, fieldOffset, hasUnion);
-      continue;
-    }
-    CharUnits fieldSize;
-    if (ci->isByRef())
-      fieldSize = CharUnits::fromQuantity(WordSizeInBytes);
-    else
-      fieldSize = CGM.getContext().getTypeSizeInChars(type);
-    UpdateRunSkipBlockVars(ci->isByRef(), getBlockCaptureLifetime(type),
-                           fieldOffset, fieldSize);
-  }
-  
-  if (RunSkipBlockVars.empty())
-    return nullPtr;
-  
   // Sort on byte position; captures might not be allocated in order,
   // and unions can do funny things.
   llvm::array_pod_sort(RunSkipBlockVars.begin(), RunSkipBlockVars.end());
   SmallVector<unsigned char, 16> Layout;
-
+  
   unsigned size = RunSkipBlockVars.size();
   for (unsigned i = 0; i < size; i++) {
     enum BLOCK_LAYOUT_OPCODE opcode = RunSkipBlockVars[i].opcode;
@@ -2320,11 +2286,11 @@ llvm::Constant *CGObjCCommonMac::BuildRCBlockLayout(CodeGenModule &CGM,
         break;
     }
     CharUnits size_in_bytes =
-      end_byte_pos - start_byte_pos + RunSkipBlockVars[j-1].block_var_size;
+    end_byte_pos - start_byte_pos + RunSkipBlockVars[j-1].block_var_size;
     if (j < size) {
       CharUnits gap =
-        RunSkipBlockVars[j].block_var_bytepos -
-        RunSkipBlockVars[j-1].block_var_bytepos - RunSkipBlockVars[j-1].block_var_size;
+      RunSkipBlockVars[j].block_var_bytepos -
+      RunSkipBlockVars[j-1].block_var_bytepos - RunSkipBlockVars[j-1].block_var_size;
       size_in_bytes += gap;
     }
     CharUnits residue_in_bytes = CharUnits::Zero();
@@ -2333,7 +2299,7 @@ llvm::Constant *CGObjCCommonMac::BuildRCBlockLayout(CodeGenModule &CGM,
       size_in_bytes -= residue_in_bytes;
       opcode = BLOCK_LAYOUT_NON_OBJECT_WORDS;
     }
-
+    
     unsigned size_in_words = size_in_bytes.getQuantity() / WordSizeInBytes;
     while (size_in_words >= 16) {
       // Note that value in imm. is one less that the actual
@@ -2350,7 +2316,7 @@ llvm::Constant *CGObjCCommonMac::BuildRCBlockLayout(CodeGenModule &CGM,
     }
     if (residue_in_bytes > CharUnits::Zero()) {
       unsigned char inst =
-        (BLOCK_LAYOUT_NON_OBJECT_BYTES << 4) | (residue_in_bytes.getQuantity()-1);
+      (BLOCK_LAYOUT_NON_OBJECT_BYTES << 4) | (residue_in_bytes.getQuantity()-1);
       Layout.push_back(inst);
     }
   }
@@ -2369,7 +2335,10 @@ llvm::Constant *CGObjCCommonMac::BuildRCBlockLayout(CodeGenModule &CGM,
   if (Result != 0) {
     // Block variable layout instruction has been inlined.
     if (CGM.getLangOpts().ObjCGCBitmapPrint) {
-      printf("\n Inline instruction for block variable layout: ");
+      if (ComputeByrefLayout)
+        printf("\n Inline instruction for BYREF variable layout: ");
+      else
+        printf("\n Inline instruction for block variable layout: ");
       printf("0x0%llx\n", (unsigned long long)Result);
     }
     if (WordSizeInBytes == 8) {
@@ -2389,7 +2358,10 @@ llvm::Constant *CGObjCCommonMac::BuildRCBlockLayout(CodeGenModule &CGM,
     BitMap += Layout[i];
   
   if (CGM.getLangOpts().ObjCGCBitmapPrint) {
-    printf("\n block variable layout: ");
+    if (ComputeByrefLayout)
+      printf("\n BYREF variable layout: ");
+    else
+      printf("\n block variable layout: ");
     for (unsigned i = 0, e = BitMap.size(); i != e; i++) {
       unsigned char inst = BitMap[i];
       enum BLOCK_LAYOUT_OPCODE opcode = (enum BLOCK_LAYOUT_OPCODE) (inst >> 4);
@@ -2417,10 +2389,10 @@ llvm::Constant *CGObjCCommonMac::BuildRCBlockLayout(CodeGenModule &CGM,
         case BLOCK_LAYOUT_UNRETAINED:
           printf("BL_UNRETAINED:");
           break;
-      } 
+      }
       // Actual value of word count is one more that what is in the imm.
       // field of the instruction
-      printf("%d", (inst & 0xf) + delta); 
+      printf("%d", (inst & 0xf) + delta);
       if (i < e-1)
         printf(", ");
       else
@@ -2429,12 +2401,80 @@ llvm::Constant *CGObjCCommonMac::BuildRCBlockLayout(CodeGenModule &CGM,
   }
   
   llvm::GlobalVariable * Entry =
-    CreateMetadataVar("\01L_OBJC_CLASS_NAME_",
+  CreateMetadataVar("\01L_OBJC_CLASS_NAME_",
                     llvm::ConstantDataArray::getString(VMContext, BitMap,false),
                     "__TEXT,__objc_classname,cstring_literals", 1, true);
   return getConstantGEP(VMContext, Entry, 0, 0);
 }
 
+llvm::Constant *CGObjCCommonMac::BuildRCBlockLayout(CodeGenModule &CGM,
+                                                    const CGBlockInfo &blockInfo) {
+  assert(CGM.getLangOpts().getGC() == LangOptions::NonGC);
+  
+  RunSkipBlockVars.clear();
+  bool hasUnion = false;
+  
+  unsigned WordSizeInBits = CGM.getContext().getTargetInfo().getPointerWidth(0);
+  unsigned ByteSizeInBits = CGM.getContext().getTargetInfo().getCharWidth();
+  unsigned WordSizeInBytes = WordSizeInBits/ByteSizeInBits;
+  
+  const BlockDecl *blockDecl = blockInfo.getBlockDecl();
+  
+  // Calculate the basic layout of the block structure.
+  const llvm::StructLayout *layout =
+  CGM.getDataLayout().getStructLayout(blockInfo.StructureType);
+  
+  // Ignore the optional 'this' capture: C++ objects are not assumed
+  // to be GC'ed.
+  
+  // Walk the captured variables.
+  for (BlockDecl::capture_const_iterator ci = blockDecl->capture_begin(),
+       ce = blockDecl->capture_end(); ci != ce; ++ci) {
+    const VarDecl *variable = ci->getVariable();
+    QualType type = variable->getType();
+    
+    const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
+    
+    // Ignore constant captures.
+    if (capture.isConstant()) continue;
+    
+    CharUnits fieldOffset =
+       CharUnits::fromQuantity(layout->getElementOffset(capture.getIndex()));
+    
+    assert(!type->isArrayType() && "array variable should not be caught");
+    if (!ci->isByRef())
+      if (const RecordType *record = type->getAs<RecordType>()) {
+        BuildRCBlockVarRecordLayout(record, fieldOffset, hasUnion);
+        continue;
+      }
+    CharUnits fieldSize;
+    if (ci->isByRef())
+      fieldSize = CharUnits::fromQuantity(WordSizeInBytes);
+    else
+      fieldSize = CGM.getContext().getTypeSizeInChars(type);
+    UpdateRunSkipBlockVars(ci->isByRef(), getBlockCaptureLifetime(type, false),
+                           fieldOffset, fieldSize);
+  }
+  return getBitmapBlockLayout(false);
+}
+
+
+llvm::Constant *CGObjCCommonMac::BuildByrefLayout(CodeGen::CodeGenModule &CGM,
+                                                  QualType T) {
+  assert(CGM.getLangOpts().getGC() == LangOptions::NonGC);
+  assert(!T->isArrayType() && "__block array variable should not be caught");
+  CharUnits fieldOffset;
+  RunSkipBlockVars.clear();
+  bool hasUnion = false;
+  if (const RecordType *record = T->getAs<RecordType>()) {
+    BuildRCBlockVarRecordLayout(record, fieldOffset, hasUnion, true /*ByrefLayout */);
+    llvm::Constant *Result = getBitmapBlockLayout(true);
+    return Result;
+  }
+  llvm::Constant *nullPtr = llvm::Constant::getNullValue(CGM.Int8PtrTy);
+  return nullPtr;
+}
+
 llvm::Value *CGObjCMac::GenerateProtocolRef(CGBuilderTy &Builder,
                                             const ObjCProtocolDecl *PD) {
   // FIXME: I don't understand why gcc generates this, or where it is
diff --git a/lib/CodeGen/CGObjCRuntime.h b/lib/CodeGen/CGObjCRuntime.h
index 3e77875e6b..17e7a9d7eb 100644
--- a/lib/CodeGen/CGObjCRuntime.h
+++ b/lib/CodeGen/CGObjCRuntime.h
@@ -263,6 +263,8 @@ public:
                                   const CodeGen::CGBlockInfo &blockInfo) = 0;
   virtual llvm::Constant *BuildRCBlockLayout(CodeGen::CodeGenModule &CGM,
                                   const CodeGen::CGBlockInfo &blockInfo) = 0;
+  virtual llvm::Constant *BuildByrefLayout(CodeGen::CodeGenModule &CGM,
+                                           QualType T) = 0;
   virtual llvm::GlobalVariable *GetClassGlobal(const std::string &Name) = 0;
 
   struct MessageSendInfo {