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| Current File : //compat/linux/proc/68247/root/usr/src/contrib/llvm/tools/clang/lib/CodeGen/CGBlocks.cpp |
//===--- CGBlocks.cpp - Emit LLVM Code for declarations -------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This contains code to emit blocks.
//
//===----------------------------------------------------------------------===//
#include "CGDebugInfo.h"
#include "CodeGenFunction.h"
#include "CGObjCRuntime.h"
#include "CodeGenModule.h"
#include "CGBlocks.h"
#include "clang/AST/DeclObjC.h"
#include "llvm/Module.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/Target/TargetData.h"
#include <algorithm>
using namespace clang;
using namespace CodeGen;
CGBlockInfo::CGBlockInfo(const BlockDecl *block, StringRef name)
: Name(name), CXXThisIndex(0), CanBeGlobal(false), NeedsCopyDispose(false),
HasCXXObject(false), UsesStret(false), StructureType(0), Block(block),
DominatingIP(0) {
// Skip asm prefix, if any. 'name' is usually taken directly from
// the mangled name of the enclosing function.
if (!name.empty() && name[0] == '\01')
name = name.substr(1);
}
// Anchor the vtable to this translation unit.
CodeGenModule::ByrefHelpers::~ByrefHelpers() {}
/// Build the given block as a global block.
static llvm::Constant *buildGlobalBlock(CodeGenModule &CGM,
const CGBlockInfo &blockInfo,
llvm::Constant *blockFn);
/// Build the helper function to copy a block.
static llvm::Constant *buildCopyHelper(CodeGenModule &CGM,
const CGBlockInfo &blockInfo) {
return CodeGenFunction(CGM).GenerateCopyHelperFunction(blockInfo);
}
/// Build the helper function to dipose of a block.
static llvm::Constant *buildDisposeHelper(CodeGenModule &CGM,
const CGBlockInfo &blockInfo) {
return CodeGenFunction(CGM).GenerateDestroyHelperFunction(blockInfo);
}
/// Build the block descriptor constant for a block.
static llvm::Constant *buildBlockDescriptor(CodeGenModule &CGM,
const CGBlockInfo &blockInfo) {
ASTContext &C = CGM.getContext();
llvm::Type *ulong = CGM.getTypes().ConvertType(C.UnsignedLongTy);
llvm::Type *i8p = CGM.getTypes().ConvertType(C.VoidPtrTy);
SmallVector<llvm::Constant*, 6> elements;
// reserved
elements.push_back(llvm::ConstantInt::get(ulong, 0));
// Size
// FIXME: What is the right way to say this doesn't fit? We should give
// a user diagnostic in that case. Better fix would be to change the
// API to size_t.
elements.push_back(llvm::ConstantInt::get(ulong,
blockInfo.BlockSize.getQuantity()));
// Optional copy/dispose helpers.
if (blockInfo.NeedsCopyDispose) {
// copy_func_helper_decl
elements.push_back(buildCopyHelper(CGM, blockInfo));
// destroy_func_decl
elements.push_back(buildDisposeHelper(CGM, blockInfo));
}
// Signature. Mandatory ObjC-style method descriptor @encode sequence.
std::string typeAtEncoding =
CGM.getContext().getObjCEncodingForBlock(blockInfo.getBlockExpr());
elements.push_back(llvm::ConstantExpr::getBitCast(
CGM.GetAddrOfConstantCString(typeAtEncoding), i8p));
// GC layout.
if (C.getLangOpts().ObjC1)
elements.push_back(CGM.getObjCRuntime().BuildGCBlockLayout(CGM, blockInfo));
else
elements.push_back(llvm::Constant::getNullValue(i8p));
llvm::Constant *init = llvm::ConstantStruct::getAnon(elements);
llvm::GlobalVariable *global =
new llvm::GlobalVariable(CGM.getModule(), init->getType(), true,
llvm::GlobalValue::InternalLinkage,
init, "__block_descriptor_tmp");
return llvm::ConstantExpr::getBitCast(global, CGM.getBlockDescriptorType());
}
/*
Purely notional variadic template describing the layout of a block.
template <class _ResultType, class... _ParamTypes, class... _CaptureTypes>
struct Block_literal {
/// Initialized to one of:
/// extern void *_NSConcreteStackBlock[];
/// extern void *_NSConcreteGlobalBlock[];
///
/// In theory, we could start one off malloc'ed by setting
/// BLOCK_NEEDS_FREE, giving it a refcount of 1, and using
/// this isa:
/// extern void *_NSConcreteMallocBlock[];
struct objc_class *isa;
/// These are the flags (with corresponding bit number) that the
/// compiler is actually supposed to know about.
/// 25. BLOCK_HAS_COPY_DISPOSE - indicates that the block
/// descriptor provides copy and dispose helper functions
/// 26. BLOCK_HAS_CXX_OBJ - indicates that there's a captured
/// object with a nontrivial destructor or copy constructor
/// 28. BLOCK_IS_GLOBAL - indicates that the block is allocated
/// as global memory
/// 29. BLOCK_USE_STRET - indicates that the block function
/// uses stret, which objc_msgSend needs to know about
/// 30. BLOCK_HAS_SIGNATURE - indicates that the block has an
/// @encoded signature string
/// And we're not supposed to manipulate these:
/// 24. BLOCK_NEEDS_FREE - indicates that the block has been moved
/// to malloc'ed memory
/// 27. BLOCK_IS_GC - indicates that the block has been moved to
/// to GC-allocated memory
/// Additionally, the bottom 16 bits are a reference count which
/// should be zero on the stack.
int flags;
/// Reserved; should be zero-initialized.
int reserved;
/// Function pointer generated from block literal.
_ResultType (*invoke)(Block_literal *, _ParamTypes...);
/// Block description metadata generated from block literal.
struct Block_descriptor *block_descriptor;
/// Captured values follow.
_CapturesTypes captures...;
};
*/
/// The number of fields in a block header.
const unsigned BlockHeaderSize = 5;
namespace {
/// A chunk of data that we actually have to capture in the block.
struct BlockLayoutChunk {
CharUnits Alignment;
CharUnits Size;
const BlockDecl::Capture *Capture; // null for 'this'
llvm::Type *Type;
BlockLayoutChunk(CharUnits align, CharUnits size,
const BlockDecl::Capture *capture,
llvm::Type *type)
: Alignment(align), Size(size), Capture(capture), Type(type) {}
/// Tell the block info that this chunk has the given field index.
void setIndex(CGBlockInfo &info, unsigned index) {
if (!Capture)
info.CXXThisIndex = index;
else
info.Captures[Capture->getVariable()]
= CGBlockInfo::Capture::makeIndex(index);
}
};
/// Order by descending alignment.
bool operator<(const BlockLayoutChunk &left, const BlockLayoutChunk &right) {
return left.Alignment > right.Alignment;
}
}
/// Determines if the given type is safe for constant capture in C++.
static bool isSafeForCXXConstantCapture(QualType type) {
const RecordType *recordType =
type->getBaseElementTypeUnsafe()->getAs<RecordType>();
// Only records can be unsafe.
if (!recordType) return true;
const CXXRecordDecl *record = cast<CXXRecordDecl>(recordType->getDecl());
// Maintain semantics for classes with non-trivial dtors or copy ctors.
if (!record->hasTrivialDestructor()) return false;
if (!record->hasTrivialCopyConstructor()) return false;
// Otherwise, we just have to make sure there aren't any mutable
// fields that might have changed since initialization.
return !record->hasMutableFields();
}
/// It is illegal to modify a const object after initialization.
/// Therefore, if a const object has a constant initializer, we don't
/// actually need to keep storage for it in the block; we'll just
/// rematerialize it at the start of the block function. This is
/// acceptable because we make no promises about address stability of
/// captured variables.
static llvm::Constant *tryCaptureAsConstant(CodeGenModule &CGM,
CodeGenFunction *CGF,
const VarDecl *var) {
QualType type = var->getType();
// We can only do this if the variable is const.
if (!type.isConstQualified()) return 0;
// Furthermore, in C++ we have to worry about mutable fields:
// C++ [dcl.type.cv]p4:
// Except that any class member declared mutable can be
// modified, any attempt to modify a const object during its
// lifetime results in undefined behavior.
if (CGM.getLangOpts().CPlusPlus && !isSafeForCXXConstantCapture(type))
return 0;
// If the variable doesn't have any initializer (shouldn't this be
// invalid?), it's not clear what we should do. Maybe capture as
// zero?
const Expr *init = var->getInit();
if (!init) return 0;
return CGM.EmitConstantInit(*var, CGF);
}
/// Get the low bit of a nonzero character count. This is the
/// alignment of the nth byte if the 0th byte is universally aligned.
static CharUnits getLowBit(CharUnits v) {
return CharUnits::fromQuantity(v.getQuantity() & (~v.getQuantity() + 1));
}
static void initializeForBlockHeader(CodeGenModule &CGM, CGBlockInfo &info,
SmallVectorImpl<llvm::Type*> &elementTypes) {
ASTContext &C = CGM.getContext();
// The header is basically a 'struct { void *; int; int; void *; void *; }'.
CharUnits ptrSize, ptrAlign, intSize, intAlign;
llvm::tie(ptrSize, ptrAlign) = C.getTypeInfoInChars(C.VoidPtrTy);
llvm::tie(intSize, intAlign) = C.getTypeInfoInChars(C.IntTy);
// Are there crazy embedded platforms where this isn't true?
assert(intSize <= ptrSize && "layout assumptions horribly violated");
CharUnits headerSize = ptrSize;
if (2 * intSize < ptrAlign) headerSize += ptrSize;
else headerSize += 2 * intSize;
headerSize += 2 * ptrSize;
info.BlockAlign = ptrAlign;
info.BlockSize = headerSize;
assert(elementTypes.empty());
llvm::Type *i8p = CGM.getTypes().ConvertType(C.VoidPtrTy);
llvm::Type *intTy = CGM.getTypes().ConvertType(C.IntTy);
elementTypes.push_back(i8p);
elementTypes.push_back(intTy);
elementTypes.push_back(intTy);
elementTypes.push_back(i8p);
elementTypes.push_back(CGM.getBlockDescriptorType());
assert(elementTypes.size() == BlockHeaderSize);
}
/// Compute the layout of the given block. Attempts to lay the block
/// out with minimal space requirements.
static void computeBlockInfo(CodeGenModule &CGM, CodeGenFunction *CGF,
CGBlockInfo &info) {
ASTContext &C = CGM.getContext();
const BlockDecl *block = info.getBlockDecl();
SmallVector<llvm::Type*, 8> elementTypes;
initializeForBlockHeader(CGM, info, elementTypes);
if (!block->hasCaptures()) {
info.StructureType =
llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true);
info.CanBeGlobal = true;
return;
}
// Collect the layout chunks.
SmallVector<BlockLayoutChunk, 16> layout;
layout.reserve(block->capturesCXXThis() +
(block->capture_end() - block->capture_begin()));
CharUnits maxFieldAlign;
// First, 'this'.
if (block->capturesCXXThis()) {
const DeclContext *DC = block->getDeclContext();
for (; isa<BlockDecl>(DC); DC = cast<BlockDecl>(DC)->getDeclContext())
;
QualType thisType;
if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(DC))
thisType = C.getPointerType(C.getRecordType(RD));
else
thisType = cast<CXXMethodDecl>(DC)->getThisType(C);
llvm::Type *llvmType = CGM.getTypes().ConvertType(thisType);
std::pair<CharUnits,CharUnits> tinfo
= CGM.getContext().getTypeInfoInChars(thisType);
maxFieldAlign = std::max(maxFieldAlign, tinfo.second);
layout.push_back(BlockLayoutChunk(tinfo.second, tinfo.first, 0, llvmType));
}
// Next, all the block captures.
for (BlockDecl::capture_const_iterator ci = block->capture_begin(),
ce = block->capture_end(); ci != ce; ++ci) {
const VarDecl *variable = ci->getVariable();
if (ci->isByRef()) {
// We have to copy/dispose of the __block reference.
info.NeedsCopyDispose = true;
// Just use void* instead of a pointer to the byref type.
QualType byRefPtrTy = C.VoidPtrTy;
llvm::Type *llvmType = CGM.getTypes().ConvertType(byRefPtrTy);
std::pair<CharUnits,CharUnits> tinfo
= CGM.getContext().getTypeInfoInChars(byRefPtrTy);
maxFieldAlign = std::max(maxFieldAlign, tinfo.second);
layout.push_back(BlockLayoutChunk(tinfo.second, tinfo.first,
&*ci, llvmType));
continue;
}
// Otherwise, build a layout chunk with the size and alignment of
// the declaration.
if (llvm::Constant *constant = tryCaptureAsConstant(CGM, CGF, variable)) {
info.Captures[variable] = CGBlockInfo::Capture::makeConstant(constant);
continue;
}
// If we have a lifetime qualifier, honor it for capture purposes.
// That includes *not* copying it if it's __unsafe_unretained.
if (Qualifiers::ObjCLifetime lifetime
= variable->getType().getObjCLifetime()) {
switch (lifetime) {
case Qualifiers::OCL_None: llvm_unreachable("impossible");
case Qualifiers::OCL_ExplicitNone:
case Qualifiers::OCL_Autoreleasing:
break;
case Qualifiers::OCL_Strong:
case Qualifiers::OCL_Weak:
info.NeedsCopyDispose = true;
}
// Block pointers require copy/dispose. So do Objective-C pointers.
} else if (variable->getType()->isObjCRetainableType()) {
info.NeedsCopyDispose = true;
// So do types that require non-trivial copy construction.
} else if (ci->hasCopyExpr()) {
info.NeedsCopyDispose = true;
info.HasCXXObject = true;
// And so do types with destructors.
} else if (CGM.getLangOpts().CPlusPlus) {
if (const CXXRecordDecl *record =
variable->getType()->getAsCXXRecordDecl()) {
if (!record->hasTrivialDestructor()) {
info.HasCXXObject = true;
info.NeedsCopyDispose = true;
}
}
}
QualType VT = variable->getType();
CharUnits size = C.getTypeSizeInChars(VT);
CharUnits align = C.getDeclAlign(variable);
maxFieldAlign = std::max(maxFieldAlign, align);
llvm::Type *llvmType =
CGM.getTypes().ConvertTypeForMem(VT);
layout.push_back(BlockLayoutChunk(align, size, &*ci, llvmType));
}
// If that was everything, we're done here.
if (layout.empty()) {
info.StructureType =
llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true);
info.CanBeGlobal = true;
return;
}
// Sort the layout by alignment. We have to use a stable sort here
// to get reproducible results. There should probably be an
// llvm::array_pod_stable_sort.
std::stable_sort(layout.begin(), layout.end());
CharUnits &blockSize = info.BlockSize;
info.BlockAlign = std::max(maxFieldAlign, info.BlockAlign);
// Assuming that the first byte in the header is maximally aligned,
// get the alignment of the first byte following the header.
CharUnits endAlign = getLowBit(blockSize);
// If the end of the header isn't satisfactorily aligned for the
// maximum thing, look for things that are okay with the header-end
// alignment, and keep appending them until we get something that's
// aligned right. This algorithm is only guaranteed optimal if
// that condition is satisfied at some point; otherwise we can get
// things like:
// header // next byte has alignment 4
// something_with_size_5; // next byte has alignment 1
// something_with_alignment_8;
// which has 7 bytes of padding, as opposed to the naive solution
// which might have less (?).
if (endAlign < maxFieldAlign) {
SmallVectorImpl<BlockLayoutChunk>::iterator
li = layout.begin() + 1, le = layout.end();
// Look for something that the header end is already
// satisfactorily aligned for.
for (; li != le && endAlign < li->Alignment; ++li)
;
// If we found something that's naturally aligned for the end of
// the header, keep adding things...
if (li != le) {
SmallVectorImpl<BlockLayoutChunk>::iterator first = li;
for (; li != le; ++li) {
assert(endAlign >= li->Alignment);
li->setIndex(info, elementTypes.size());
elementTypes.push_back(li->Type);
blockSize += li->Size;
endAlign = getLowBit(blockSize);
// ...until we get to the alignment of the maximum field.
if (endAlign >= maxFieldAlign)
break;
}
// Don't re-append everything we just appended.
layout.erase(first, li);
}
}
// At this point, we just have to add padding if the end align still
// isn't aligned right.
if (endAlign < maxFieldAlign) {
CharUnits padding = maxFieldAlign - endAlign;
elementTypes.push_back(llvm::ArrayType::get(CGM.Int8Ty,
padding.getQuantity()));
blockSize += padding;
endAlign = getLowBit(blockSize);
assert(endAlign >= maxFieldAlign);
}
// Slam everything else on now. This works because they have
// strictly decreasing alignment and we expect that size is always a
// multiple of alignment.
for (SmallVectorImpl<BlockLayoutChunk>::iterator
li = layout.begin(), le = layout.end(); li != le; ++li) {
assert(endAlign >= li->Alignment);
li->setIndex(info, elementTypes.size());
elementTypes.push_back(li->Type);
blockSize += li->Size;
endAlign = getLowBit(blockSize);
}
info.StructureType =
llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true);
}
/// Enter the scope of a block. This should be run at the entrance to
/// a full-expression so that the block's cleanups are pushed at the
/// right place in the stack.
static void enterBlockScope(CodeGenFunction &CGF, BlockDecl *block) {
assert(CGF.HaveInsertPoint());
// Allocate the block info and place it at the head of the list.
CGBlockInfo &blockInfo =
*new CGBlockInfo(block, CGF.CurFn->getName());
blockInfo.NextBlockInfo = CGF.FirstBlockInfo;
CGF.FirstBlockInfo = &blockInfo;
// Compute information about the layout, etc., of this block,
// pushing cleanups as necessary.
computeBlockInfo(CGF.CGM, &CGF, blockInfo);
// Nothing else to do if it can be global.
if (blockInfo.CanBeGlobal) return;
// Make the allocation for the block.
blockInfo.Address =
CGF.CreateTempAlloca(blockInfo.StructureType, "block");
blockInfo.Address->setAlignment(blockInfo.BlockAlign.getQuantity());
// If there are cleanups to emit, enter them (but inactive).
if (!blockInfo.NeedsCopyDispose) return;
// Walk through the captures (in order) and find the ones not
// captured by constant.
for (BlockDecl::capture_const_iterator ci = block->capture_begin(),
ce = block->capture_end(); ci != ce; ++ci) {
// Ignore __block captures; there's nothing special in the
// on-stack block that we need to do for them.
if (ci->isByRef()) continue;
// Ignore variables that are constant-captured.
const VarDecl *variable = ci->getVariable();
CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
if (capture.isConstant()) continue;
// Ignore objects that aren't destructed.
QualType::DestructionKind dtorKind =
variable->getType().isDestructedType();
if (dtorKind == QualType::DK_none) continue;
CodeGenFunction::Destroyer *destroyer;
// Block captures count as local values and have imprecise semantics.
// They also can't be arrays, so need to worry about that.
if (dtorKind == QualType::DK_objc_strong_lifetime) {
destroyer = CodeGenFunction::destroyARCStrongImprecise;
} else {
destroyer = CGF.getDestroyer(dtorKind);
}
// GEP down to the address.
llvm::Value *addr = CGF.Builder.CreateStructGEP(blockInfo.Address,
capture.getIndex());
// We can use that GEP as the dominating IP.
if (!blockInfo.DominatingIP)
blockInfo.DominatingIP = cast<llvm::Instruction>(addr);
CleanupKind cleanupKind = InactiveNormalCleanup;
bool useArrayEHCleanup = CGF.needsEHCleanup(dtorKind);
if (useArrayEHCleanup)
cleanupKind = InactiveNormalAndEHCleanup;
CGF.pushDestroy(cleanupKind, addr, variable->getType(),
destroyer, useArrayEHCleanup);
// Remember where that cleanup was.
capture.setCleanup(CGF.EHStack.stable_begin());
}
}
/// Enter a full-expression with a non-trivial number of objects to
/// clean up. This is in this file because, at the moment, the only
/// kind of cleanup object is a BlockDecl*.
void CodeGenFunction::enterNonTrivialFullExpression(const ExprWithCleanups *E) {
assert(E->getNumObjects() != 0);
ArrayRef<ExprWithCleanups::CleanupObject> cleanups = E->getObjects();
for (ArrayRef<ExprWithCleanups::CleanupObject>::iterator
i = cleanups.begin(), e = cleanups.end(); i != e; ++i) {
enterBlockScope(*this, *i);
}
}
/// Find the layout for the given block in a linked list and remove it.
static CGBlockInfo *findAndRemoveBlockInfo(CGBlockInfo **head,
const BlockDecl *block) {
while (true) {
assert(head && *head);
CGBlockInfo *cur = *head;
// If this is the block we're looking for, splice it out of the list.
if (cur->getBlockDecl() == block) {
*head = cur->NextBlockInfo;
return cur;
}
head = &cur->NextBlockInfo;
}
}
/// Destroy a chain of block layouts.
void CodeGenFunction::destroyBlockInfos(CGBlockInfo *head) {
assert(head && "destroying an empty chain");
do {
CGBlockInfo *cur = head;
head = cur->NextBlockInfo;
delete cur;
} while (head != 0);
}
/// Emit a block literal expression in the current function.
llvm::Value *CodeGenFunction::EmitBlockLiteral(const BlockExpr *blockExpr) {
// If the block has no captures, we won't have a pre-computed
// layout for it.
if (!blockExpr->getBlockDecl()->hasCaptures()) {
CGBlockInfo blockInfo(blockExpr->getBlockDecl(), CurFn->getName());
computeBlockInfo(CGM, this, blockInfo);
blockInfo.BlockExpression = blockExpr;
return EmitBlockLiteral(blockInfo);
}
// Find the block info for this block and take ownership of it.
OwningPtr<CGBlockInfo> blockInfo;
blockInfo.reset(findAndRemoveBlockInfo(&FirstBlockInfo,
blockExpr->getBlockDecl()));
blockInfo->BlockExpression = blockExpr;
return EmitBlockLiteral(*blockInfo);
}
llvm::Value *CodeGenFunction::EmitBlockLiteral(const CGBlockInfo &blockInfo) {
// Using the computed layout, generate the actual block function.
bool isLambdaConv = blockInfo.getBlockDecl()->isConversionFromLambda();
llvm::Constant *blockFn
= CodeGenFunction(CGM).GenerateBlockFunction(CurGD, blockInfo,
CurFuncDecl, LocalDeclMap,
isLambdaConv);
blockFn = llvm::ConstantExpr::getBitCast(blockFn, VoidPtrTy);
// If there is nothing to capture, we can emit this as a global block.
if (blockInfo.CanBeGlobal)
return buildGlobalBlock(CGM, blockInfo, blockFn);
// Otherwise, we have to emit this as a local block.
llvm::Constant *isa = CGM.getNSConcreteStackBlock();
isa = llvm::ConstantExpr::getBitCast(isa, VoidPtrTy);
// Build the block descriptor.
llvm::Constant *descriptor = buildBlockDescriptor(CGM, blockInfo);
llvm::AllocaInst *blockAddr = blockInfo.Address;
assert(blockAddr && "block has no address!");
// Compute the initial on-stack block flags.
BlockFlags flags = BLOCK_HAS_SIGNATURE;
if (blockInfo.NeedsCopyDispose) flags |= BLOCK_HAS_COPY_DISPOSE;
if (blockInfo.HasCXXObject) flags |= BLOCK_HAS_CXX_OBJ;
if (blockInfo.UsesStret) flags |= BLOCK_USE_STRET;
// Initialize the block literal.
Builder.CreateStore(isa, Builder.CreateStructGEP(blockAddr, 0, "block.isa"));
Builder.CreateStore(llvm::ConstantInt::get(IntTy, flags.getBitMask()),
Builder.CreateStructGEP(blockAddr, 1, "block.flags"));
Builder.CreateStore(llvm::ConstantInt::get(IntTy, 0),
Builder.CreateStructGEP(blockAddr, 2, "block.reserved"));
Builder.CreateStore(blockFn, Builder.CreateStructGEP(blockAddr, 3,
"block.invoke"));
Builder.CreateStore(descriptor, Builder.CreateStructGEP(blockAddr, 4,
"block.descriptor"));
// Finally, capture all the values into the block.
const BlockDecl *blockDecl = blockInfo.getBlockDecl();
// First, 'this'.
if (blockDecl->capturesCXXThis()) {
llvm::Value *addr = Builder.CreateStructGEP(blockAddr,
blockInfo.CXXThisIndex,
"block.captured-this.addr");
Builder.CreateStore(LoadCXXThis(), addr);
}
// Next, captured variables.
for (BlockDecl::capture_const_iterator ci = blockDecl->capture_begin(),
ce = blockDecl->capture_end(); ci != ce; ++ci) {
const VarDecl *variable = ci->getVariable();
const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
// Ignore constant captures.
if (capture.isConstant()) continue;
QualType type = variable->getType();
// This will be a [[type]]*, except that a byref entry will just be
// an i8**.
llvm::Value *blockField =
Builder.CreateStructGEP(blockAddr, capture.getIndex(),
"block.captured");
// Compute the address of the thing we're going to move into the
// block literal.
llvm::Value *src;
if (ci->isNested()) {
// We need to use the capture from the enclosing block.
const CGBlockInfo::Capture &enclosingCapture =
BlockInfo->getCapture(variable);
// This is a [[type]]*, except that a byref entry wil just be an i8**.
src = Builder.CreateStructGEP(LoadBlockStruct(),
enclosingCapture.getIndex(),
"block.capture.addr");
} else if (blockDecl->isConversionFromLambda()) {
// The lambda capture in a lambda's conversion-to-block-pointer is
// special; we'll simply emit it directly.
src = 0;
} else {
// This is a [[type]]*.
src = LocalDeclMap[variable];
}
// For byrefs, we just write the pointer to the byref struct into
// the block field. There's no need to chase the forwarding
// pointer at this point, since we're building something that will
// live a shorter life than the stack byref anyway.
if (ci->isByRef()) {
// Get a void* that points to the byref struct.
if (ci->isNested())
src = Builder.CreateLoad(src, "byref.capture");
else
src = Builder.CreateBitCast(src, VoidPtrTy);
// Write that void* into the capture field.
Builder.CreateStore(src, blockField);
// If we have a copy constructor, evaluate that into the block field.
} else if (const Expr *copyExpr = ci->getCopyExpr()) {
if (blockDecl->isConversionFromLambda()) {
// If we have a lambda conversion, emit the expression
// directly into the block instead.
CharUnits Align = getContext().getTypeAlignInChars(type);
AggValueSlot Slot =
AggValueSlot::forAddr(blockField, Align, Qualifiers(),
AggValueSlot::IsDestructed,
AggValueSlot::DoesNotNeedGCBarriers,
AggValueSlot::IsNotAliased);
EmitAggExpr(copyExpr, Slot);
} else {
EmitSynthesizedCXXCopyCtor(blockField, src, copyExpr);
}
// If it's a reference variable, copy the reference into the block field.
} else if (type->isReferenceType()) {
Builder.CreateStore(Builder.CreateLoad(src, "ref.val"), blockField);
// Otherwise, fake up a POD copy into the block field.
} else {
// Fake up a new variable so that EmitScalarInit doesn't think
// we're referring to the variable in its own initializer.
ImplicitParamDecl blockFieldPseudoVar(/*DC*/ 0, SourceLocation(),
/*name*/ 0, type);
// We use one of these or the other depending on whether the
// reference is nested.
DeclRefExpr declRef(const_cast<VarDecl*>(variable),
/*refersToEnclosing*/ ci->isNested(), type,
VK_LValue, SourceLocation());
ImplicitCastExpr l2r(ImplicitCastExpr::OnStack, type, CK_LValueToRValue,
&declRef, VK_RValue);
EmitExprAsInit(&l2r, &blockFieldPseudoVar,
MakeAddrLValue(blockField, type,
getContext().getDeclAlign(variable)),
/*captured by init*/ false);
}
// Activate the cleanup if layout pushed one.
if (!ci->isByRef()) {
EHScopeStack::stable_iterator cleanup = capture.getCleanup();
if (cleanup.isValid())
ActivateCleanupBlock(cleanup, blockInfo.DominatingIP);
}
}
// Cast to the converted block-pointer type, which happens (somewhat
// unfortunately) to be a pointer to function type.
llvm::Value *result =
Builder.CreateBitCast(blockAddr,
ConvertType(blockInfo.getBlockExpr()->getType()));
return result;
}
llvm::Type *CodeGenModule::getBlockDescriptorType() {
if (BlockDescriptorType)
return BlockDescriptorType;
llvm::Type *UnsignedLongTy =
getTypes().ConvertType(getContext().UnsignedLongTy);
// struct __block_descriptor {
// unsigned long reserved;
// unsigned long block_size;
//
// // later, the following will be added
//
// struct {
// void (*copyHelper)();
// void (*copyHelper)();
// } helpers; // !!! optional
//
// const char *signature; // the block signature
// const char *layout; // reserved
// };
BlockDescriptorType =
llvm::StructType::create("struct.__block_descriptor",
UnsignedLongTy, UnsignedLongTy, NULL);
// Now form a pointer to that.
BlockDescriptorType = llvm::PointerType::getUnqual(BlockDescriptorType);
return BlockDescriptorType;
}
llvm::Type *CodeGenModule::getGenericBlockLiteralType() {
if (GenericBlockLiteralType)
return GenericBlockLiteralType;
llvm::Type *BlockDescPtrTy = getBlockDescriptorType();
// struct __block_literal_generic {
// void *__isa;
// int __flags;
// int __reserved;
// void (*__invoke)(void *);
// struct __block_descriptor *__descriptor;
// };
GenericBlockLiteralType =
llvm::StructType::create("struct.__block_literal_generic",
VoidPtrTy, IntTy, IntTy, VoidPtrTy,
BlockDescPtrTy, NULL);
return GenericBlockLiteralType;
}
RValue CodeGenFunction::EmitBlockCallExpr(const CallExpr* E,
ReturnValueSlot ReturnValue) {
const BlockPointerType *BPT =
E->getCallee()->getType()->getAs<BlockPointerType>();
llvm::Value *Callee = EmitScalarExpr(E->getCallee());
// Get a pointer to the generic block literal.
llvm::Type *BlockLiteralTy =
llvm::PointerType::getUnqual(CGM.getGenericBlockLiteralType());
// Bitcast the callee to a block literal.
llvm::Value *BlockLiteral =
Builder.CreateBitCast(Callee, BlockLiteralTy, "block.literal");
// Get the function pointer from the literal.
llvm::Value *FuncPtr = Builder.CreateStructGEP(BlockLiteral, 3);
BlockLiteral = Builder.CreateBitCast(BlockLiteral, VoidPtrTy);
// Add the block literal.
CallArgList Args;
Args.add(RValue::get(BlockLiteral), getContext().VoidPtrTy);
QualType FnType = BPT->getPointeeType();
// And the rest of the arguments.
EmitCallArgs(Args, FnType->getAs<FunctionProtoType>(),
E->arg_begin(), E->arg_end());
// Load the function.
llvm::Value *Func = Builder.CreateLoad(FuncPtr);
const FunctionType *FuncTy = FnType->castAs<FunctionType>();
const CGFunctionInfo &FnInfo =
CGM.getTypes().arrangeFunctionCall(Args, FuncTy);
// Cast the function pointer to the right type.
llvm::Type *BlockFTy = CGM.getTypes().GetFunctionType(FnInfo);
llvm::Type *BlockFTyPtr = llvm::PointerType::getUnqual(BlockFTy);
Func = Builder.CreateBitCast(Func, BlockFTyPtr);
// And call the block.
return EmitCall(FnInfo, Func, ReturnValue, Args);
}
llvm::Value *CodeGenFunction::GetAddrOfBlockDecl(const VarDecl *variable,
bool isByRef) {
assert(BlockInfo && "evaluating block ref without block information?");
const CGBlockInfo::Capture &capture = BlockInfo->getCapture(variable);
// Handle constant captures.
if (capture.isConstant()) return LocalDeclMap[variable];
llvm::Value *addr =
Builder.CreateStructGEP(LoadBlockStruct(), capture.getIndex(),
"block.capture.addr");
if (isByRef) {
// addr should be a void** right now. Load, then cast the result
// to byref*.
addr = Builder.CreateLoad(addr);
llvm::PointerType *byrefPointerType
= llvm::PointerType::get(BuildByRefType(variable), 0);
addr = Builder.CreateBitCast(addr, byrefPointerType,
"byref.addr");
// Follow the forwarding pointer.
addr = Builder.CreateStructGEP(addr, 1, "byref.forwarding");
addr = Builder.CreateLoad(addr, "byref.addr.forwarded");
// Cast back to byref* and GEP over to the actual object.
addr = Builder.CreateBitCast(addr, byrefPointerType);
addr = Builder.CreateStructGEP(addr, getByRefValueLLVMField(variable),
variable->getNameAsString());
}
if (variable->getType()->isReferenceType())
addr = Builder.CreateLoad(addr, "ref.tmp");
return addr;
}
llvm::Constant *
CodeGenModule::GetAddrOfGlobalBlock(const BlockExpr *blockExpr,
const char *name) {
CGBlockInfo blockInfo(blockExpr->getBlockDecl(), name);
blockInfo.BlockExpression = blockExpr;
// Compute information about the layout, etc., of this block.
computeBlockInfo(*this, 0, blockInfo);
// Using that metadata, generate the actual block function.
llvm::Constant *blockFn;
{
llvm::DenseMap<const Decl*, llvm::Value*> LocalDeclMap;
blockFn = CodeGenFunction(*this).GenerateBlockFunction(GlobalDecl(),
blockInfo,
0, LocalDeclMap,
false);
}
blockFn = llvm::ConstantExpr::getBitCast(blockFn, VoidPtrTy);
return buildGlobalBlock(*this, blockInfo, blockFn);
}
static llvm::Constant *buildGlobalBlock(CodeGenModule &CGM,
const CGBlockInfo &blockInfo,
llvm::Constant *blockFn) {
assert(blockInfo.CanBeGlobal);
// Generate the constants for the block literal initializer.
llvm::Constant *fields[BlockHeaderSize];
// isa
fields[0] = CGM.getNSConcreteGlobalBlock();
// __flags
BlockFlags flags = BLOCK_IS_GLOBAL | BLOCK_HAS_SIGNATURE;
if (blockInfo.UsesStret) flags |= BLOCK_USE_STRET;
fields[1] = llvm::ConstantInt::get(CGM.IntTy, flags.getBitMask());
// Reserved
fields[2] = llvm::Constant::getNullValue(CGM.IntTy);
// Function
fields[3] = blockFn;
// Descriptor
fields[4] = buildBlockDescriptor(CGM, blockInfo);
llvm::Constant *init = llvm::ConstantStruct::getAnon(fields);
llvm::GlobalVariable *literal =
new llvm::GlobalVariable(CGM.getModule(),
init->getType(),
/*constant*/ true,
llvm::GlobalVariable::InternalLinkage,
init,
"__block_literal_global");
literal->setAlignment(blockInfo.BlockAlign.getQuantity());
// Return a constant of the appropriately-casted type.
llvm::Type *requiredType =
CGM.getTypes().ConvertType(blockInfo.getBlockExpr()->getType());
return llvm::ConstantExpr::getBitCast(literal, requiredType);
}
llvm::Function *
CodeGenFunction::GenerateBlockFunction(GlobalDecl GD,
const CGBlockInfo &blockInfo,
const Decl *outerFnDecl,
const DeclMapTy &ldm,
bool IsLambdaConversionToBlock) {
const BlockDecl *blockDecl = blockInfo.getBlockDecl();
// Check if we should generate debug info for this block function.
if (CGM.getModuleDebugInfo())
DebugInfo = CGM.getModuleDebugInfo();
BlockInfo = &blockInfo;
// Arrange for local static and local extern declarations to appear
// to be local to this function as well, in case they're directly
// referenced in a block.
for (DeclMapTy::const_iterator i = ldm.begin(), e = ldm.end(); i != e; ++i) {
const VarDecl *var = dyn_cast<VarDecl>(i->first);
if (var && !var->hasLocalStorage())
LocalDeclMap[var] = i->second;
}
// Begin building the function declaration.
// Build the argument list.
FunctionArgList args;
// The first argument is the block pointer. Just take it as a void*
// and cast it later.
QualType selfTy = getContext().VoidPtrTy;
IdentifierInfo *II = &CGM.getContext().Idents.get(".block_descriptor");
ImplicitParamDecl selfDecl(const_cast<BlockDecl*>(blockDecl),
SourceLocation(), II, selfTy);
args.push_back(&selfDecl);
// Now add the rest of the parameters.
for (BlockDecl::param_const_iterator i = blockDecl->param_begin(),
e = blockDecl->param_end(); i != e; ++i)
args.push_back(*i);
// Create the function declaration.
const FunctionProtoType *fnType = blockInfo.getBlockExpr()->getFunctionType();
const CGFunctionInfo &fnInfo =
CGM.getTypes().arrangeFunctionDeclaration(fnType->getResultType(), args,
fnType->getExtInfo(),
fnType->isVariadic());
if (CGM.ReturnTypeUsesSRet(fnInfo))
blockInfo.UsesStret = true;
llvm::FunctionType *fnLLVMType = CGM.getTypes().GetFunctionType(fnInfo);
MangleBuffer name;
CGM.getBlockMangledName(GD, name, blockDecl);
llvm::Function *fn =
llvm::Function::Create(fnLLVMType, llvm::GlobalValue::InternalLinkage,
name.getString(), &CGM.getModule());
CGM.SetInternalFunctionAttributes(blockDecl, fn, fnInfo);
// Begin generating the function.
StartFunction(blockDecl, fnType->getResultType(), fn, fnInfo, args,
blockInfo.getBlockExpr()->getBody()->getLocStart());
CurFuncDecl = outerFnDecl; // StartFunction sets this to blockDecl
// Okay. Undo some of what StartFunction did.
// Pull the 'self' reference out of the local decl map.
llvm::Value *blockAddr = LocalDeclMap[&selfDecl];
LocalDeclMap.erase(&selfDecl);
BlockPointer = Builder.CreateBitCast(blockAddr,
blockInfo.StructureType->getPointerTo(),
"block");
// If we have a C++ 'this' reference, go ahead and force it into
// existence now.
if (blockDecl->capturesCXXThis()) {
llvm::Value *addr = Builder.CreateStructGEP(BlockPointer,
blockInfo.CXXThisIndex,
"block.captured-this");
CXXThisValue = Builder.CreateLoad(addr, "this");
}
// LoadObjCSelf() expects there to be an entry for 'self' in LocalDeclMap;
// appease it.
if (const ObjCMethodDecl *method
= dyn_cast_or_null<ObjCMethodDecl>(CurFuncDecl)) {
const VarDecl *self = method->getSelfDecl();
// There might not be a capture for 'self', but if there is...
if (blockInfo.Captures.count(self)) {
const CGBlockInfo::Capture &capture = blockInfo.getCapture(self);
llvm::Value *selfAddr = Builder.CreateStructGEP(BlockPointer,
capture.getIndex(),
"block.captured-self");
LocalDeclMap[self] = selfAddr;
}
}
// Also force all the constant captures.
for (BlockDecl::capture_const_iterator ci = blockDecl->capture_begin(),
ce = blockDecl->capture_end(); ci != ce; ++ci) {
const VarDecl *variable = ci->getVariable();
const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
if (!capture.isConstant()) continue;
unsigned align = getContext().getDeclAlign(variable).getQuantity();
llvm::AllocaInst *alloca =
CreateMemTemp(variable->getType(), "block.captured-const");
alloca->setAlignment(align);
Builder.CreateStore(capture.getConstant(), alloca, align);
LocalDeclMap[variable] = alloca;
}
// Save a spot to insert the debug information for all the DeclRefExprs.
llvm::BasicBlock *entry = Builder.GetInsertBlock();
llvm::BasicBlock::iterator entry_ptr = Builder.GetInsertPoint();
--entry_ptr;
if (IsLambdaConversionToBlock)
EmitLambdaBlockInvokeBody();
else
EmitStmt(blockDecl->getBody());
// Remember where we were...
llvm::BasicBlock *resume = Builder.GetInsertBlock();
// Go back to the entry.
++entry_ptr;
Builder.SetInsertPoint(entry, entry_ptr);
// Emit debug information for all the DeclRefExprs.
// FIXME: also for 'this'
if (CGDebugInfo *DI = getDebugInfo()) {
for (BlockDecl::capture_const_iterator ci = blockDecl->capture_begin(),
ce = blockDecl->capture_end(); ci != ce; ++ci) {
const VarDecl *variable = ci->getVariable();
DI->EmitLocation(Builder, variable->getLocation());
const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
if (capture.isConstant()) {
DI->EmitDeclareOfAutoVariable(variable, LocalDeclMap[variable],
Builder);
continue;
}
DI->EmitDeclareOfBlockDeclRefVariable(variable, BlockPointer,
Builder, blockInfo);
}
}
// And resume where we left off.
if (resume == 0)
Builder.ClearInsertionPoint();
else
Builder.SetInsertPoint(resume);
FinishFunction(cast<CompoundStmt>(blockDecl->getBody())->getRBracLoc());
return fn;
}
/*
notes.push_back(HelperInfo());
HelperInfo ¬e = notes.back();
note.index = capture.getIndex();
note.RequiresCopying = (ci->hasCopyExpr() || BlockRequiresCopying(type));
note.cxxbar_import = ci->getCopyExpr();
if (ci->isByRef()) {
note.flag = BLOCK_FIELD_IS_BYREF;
if (type.isObjCGCWeak())
note.flag |= BLOCK_FIELD_IS_WEAK;
} else if (type->isBlockPointerType()) {
note.flag = BLOCK_FIELD_IS_BLOCK;
} else {
note.flag = BLOCK_FIELD_IS_OBJECT;
}
*/
llvm::Constant *
CodeGenFunction::GenerateCopyHelperFunction(const CGBlockInfo &blockInfo) {
ASTContext &C = getContext();
FunctionArgList args;
ImplicitParamDecl dstDecl(0, SourceLocation(), 0, C.VoidPtrTy);
args.push_back(&dstDecl);
ImplicitParamDecl srcDecl(0, SourceLocation(), 0, C.VoidPtrTy);
args.push_back(&srcDecl);
const CGFunctionInfo &FI =
CGM.getTypes().arrangeFunctionDeclaration(C.VoidTy, args,
FunctionType::ExtInfo(),
/*variadic*/ false);
// FIXME: it would be nice if these were mergeable with things with
// identical semantics.
llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI);
llvm::Function *Fn =
llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
"__copy_helper_block_", &CGM.getModule());
IdentifierInfo *II
= &CGM.getContext().Idents.get("__copy_helper_block_");
// Check if we should generate debug info for this block helper function.
if (CGM.getModuleDebugInfo())
DebugInfo = CGM.getModuleDebugInfo();
FunctionDecl *FD = FunctionDecl::Create(C,
C.getTranslationUnitDecl(),
SourceLocation(),
SourceLocation(), II, C.VoidTy, 0,
SC_Static,
SC_None,
false,
false);
StartFunction(FD, C.VoidTy, Fn, FI, args, SourceLocation());
llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo();
llvm::Value *src = GetAddrOfLocalVar(&srcDecl);
src = Builder.CreateLoad(src);
src = Builder.CreateBitCast(src, structPtrTy, "block.source");
llvm::Value *dst = GetAddrOfLocalVar(&dstDecl);
dst = Builder.CreateLoad(dst);
dst = Builder.CreateBitCast(dst, structPtrTy, "block.dest");
const BlockDecl *blockDecl = blockInfo.getBlockDecl();
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);
if (capture.isConstant()) continue;
const Expr *copyExpr = ci->getCopyExpr();
BlockFieldFlags flags;
bool isARCWeakCapture = false;
if (copyExpr) {
assert(!ci->isByRef());
// don't bother computing flags
} else if (ci->isByRef()) {
flags = BLOCK_FIELD_IS_BYREF;
if (type.isObjCGCWeak())
flags |= BLOCK_FIELD_IS_WEAK;
} else if (type->isObjCRetainableType()) {
flags = BLOCK_FIELD_IS_OBJECT;
if (type->isBlockPointerType())
flags = BLOCK_FIELD_IS_BLOCK;
// Special rules for ARC captures:
if (getLangOpts().ObjCAutoRefCount) {
Qualifiers qs = type.getQualifiers();
// Don't generate special copy logic for a captured object
// unless it's __strong or __weak.
if (!qs.hasStrongOrWeakObjCLifetime())
continue;
// Support __weak direct captures.
if (qs.getObjCLifetime() == Qualifiers::OCL_Weak)
isARCWeakCapture = true;
}
} else {
continue;
}
unsigned index = capture.getIndex();
llvm::Value *srcField = Builder.CreateStructGEP(src, index);
llvm::Value *dstField = Builder.CreateStructGEP(dst, index);
// If there's an explicit copy expression, we do that.
if (copyExpr) {
EmitSynthesizedCXXCopyCtor(dstField, srcField, copyExpr);
} else if (isARCWeakCapture) {
EmitARCCopyWeak(dstField, srcField);
} else {
llvm::Value *srcValue = Builder.CreateLoad(srcField, "blockcopy.src");
srcValue = Builder.CreateBitCast(srcValue, VoidPtrTy);
llvm::Value *dstAddr = Builder.CreateBitCast(dstField, VoidPtrTy);
Builder.CreateCall3(CGM.getBlockObjectAssign(), dstAddr, srcValue,
llvm::ConstantInt::get(Int32Ty, flags.getBitMask()));
}
}
FinishFunction();
return llvm::ConstantExpr::getBitCast(Fn, VoidPtrTy);
}
llvm::Constant *
CodeGenFunction::GenerateDestroyHelperFunction(const CGBlockInfo &blockInfo) {
ASTContext &C = getContext();
FunctionArgList args;
ImplicitParamDecl srcDecl(0, SourceLocation(), 0, C.VoidPtrTy);
args.push_back(&srcDecl);
const CGFunctionInfo &FI =
CGM.getTypes().arrangeFunctionDeclaration(C.VoidTy, args,
FunctionType::ExtInfo(),
/*variadic*/ false);
// FIXME: We'd like to put these into a mergable by content, with
// internal linkage.
llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI);
llvm::Function *Fn =
llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
"__destroy_helper_block_", &CGM.getModule());
// Check if we should generate debug info for this block destroy function.
if (CGM.getModuleDebugInfo())
DebugInfo = CGM.getModuleDebugInfo();
IdentifierInfo *II
= &CGM.getContext().Idents.get("__destroy_helper_block_");
FunctionDecl *FD = FunctionDecl::Create(C, C.getTranslationUnitDecl(),
SourceLocation(),
SourceLocation(), II, C.VoidTy, 0,
SC_Static,
SC_None,
false, false);
StartFunction(FD, C.VoidTy, Fn, FI, args, SourceLocation());
llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo();
llvm::Value *src = GetAddrOfLocalVar(&srcDecl);
src = Builder.CreateLoad(src);
src = Builder.CreateBitCast(src, structPtrTy, "block");
const BlockDecl *blockDecl = blockInfo.getBlockDecl();
CodeGenFunction::RunCleanupsScope cleanups(*this);
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);
if (capture.isConstant()) continue;
BlockFieldFlags flags;
const CXXDestructorDecl *dtor = 0;
bool isARCWeakCapture = false;
if (ci->isByRef()) {
flags = BLOCK_FIELD_IS_BYREF;
if (type.isObjCGCWeak())
flags |= BLOCK_FIELD_IS_WEAK;
} else if (const CXXRecordDecl *record = type->getAsCXXRecordDecl()) {
if (record->hasTrivialDestructor())
continue;
dtor = record->getDestructor();
} else if (type->isObjCRetainableType()) {
flags = BLOCK_FIELD_IS_OBJECT;
if (type->isBlockPointerType())
flags = BLOCK_FIELD_IS_BLOCK;
// Special rules for ARC captures.
if (getLangOpts().ObjCAutoRefCount) {
Qualifiers qs = type.getQualifiers();
// Don't generate special dispose logic for a captured object
// unless it's __strong or __weak.
if (!qs.hasStrongOrWeakObjCLifetime())
continue;
// Support __weak direct captures.
if (qs.getObjCLifetime() == Qualifiers::OCL_Weak)
isARCWeakCapture = true;
}
} else {
continue;
}
unsigned index = capture.getIndex();
llvm::Value *srcField = Builder.CreateStructGEP(src, index);
// If there's an explicit copy expression, we do that.
if (dtor) {
PushDestructorCleanup(dtor, srcField);
// If this is a __weak capture, emit the release directly.
} else if (isARCWeakCapture) {
EmitARCDestroyWeak(srcField);
// Otherwise we call _Block_object_dispose. It wouldn't be too
// hard to just emit this as a cleanup if we wanted to make sure
// that things were done in reverse.
} else {
llvm::Value *value = Builder.CreateLoad(srcField);
value = Builder.CreateBitCast(value, VoidPtrTy);
BuildBlockRelease(value, flags);
}
}
cleanups.ForceCleanup();
FinishFunction();
return llvm::ConstantExpr::getBitCast(Fn, VoidPtrTy);
}
namespace {
/// Emits the copy/dispose helper functions for a __block object of id type.
class ObjectByrefHelpers : public CodeGenModule::ByrefHelpers {
BlockFieldFlags Flags;
public:
ObjectByrefHelpers(CharUnits alignment, BlockFieldFlags flags)
: ByrefHelpers(alignment), Flags(flags) {}
void emitCopy(CodeGenFunction &CGF, llvm::Value *destField,
llvm::Value *srcField) {
destField = CGF.Builder.CreateBitCast(destField, CGF.VoidPtrTy);
srcField = CGF.Builder.CreateBitCast(srcField, CGF.VoidPtrPtrTy);
llvm::Value *srcValue = CGF.Builder.CreateLoad(srcField);
unsigned flags = (Flags | BLOCK_BYREF_CALLER).getBitMask();
llvm::Value *flagsVal = llvm::ConstantInt::get(CGF.Int32Ty, flags);
llvm::Value *fn = CGF.CGM.getBlockObjectAssign();
CGF.Builder.CreateCall3(fn, destField, srcValue, flagsVal);
}
void emitDispose(CodeGenFunction &CGF, llvm::Value *field) {
field = CGF.Builder.CreateBitCast(field, CGF.Int8PtrTy->getPointerTo(0));
llvm::Value *value = CGF.Builder.CreateLoad(field);
CGF.BuildBlockRelease(value, Flags | BLOCK_BYREF_CALLER);
}
void profileImpl(llvm::FoldingSetNodeID &id) const {
id.AddInteger(Flags.getBitMask());
}
};
/// Emits the copy/dispose helpers for an ARC __block __weak variable.
class ARCWeakByrefHelpers : public CodeGenModule::ByrefHelpers {
public:
ARCWeakByrefHelpers(CharUnits alignment) : ByrefHelpers(alignment) {}
void emitCopy(CodeGenFunction &CGF, llvm::Value *destField,
llvm::Value *srcField) {
CGF.EmitARCMoveWeak(destField, srcField);
}
void emitDispose(CodeGenFunction &CGF, llvm::Value *field) {
CGF.EmitARCDestroyWeak(field);
}
void profileImpl(llvm::FoldingSetNodeID &id) const {
// 0 is distinguishable from all pointers and byref flags
id.AddInteger(0);
}
};
/// Emits the copy/dispose helpers for an ARC __block __strong variable
/// that's not of block-pointer type.
class ARCStrongByrefHelpers : public CodeGenModule::ByrefHelpers {
public:
ARCStrongByrefHelpers(CharUnits alignment) : ByrefHelpers(alignment) {}
void emitCopy(CodeGenFunction &CGF, llvm::Value *destField,
llvm::Value *srcField) {
// Do a "move" by copying the value and then zeroing out the old
// variable.
llvm::LoadInst *value = CGF.Builder.CreateLoad(srcField);
value->setAlignment(Alignment.getQuantity());
llvm::Value *null =
llvm::ConstantPointerNull::get(cast<llvm::PointerType>(value->getType()));
llvm::StoreInst *store = CGF.Builder.CreateStore(value, destField);
store->setAlignment(Alignment.getQuantity());
store = CGF.Builder.CreateStore(null, srcField);
store->setAlignment(Alignment.getQuantity());
}
void emitDispose(CodeGenFunction &CGF, llvm::Value *field) {
llvm::LoadInst *value = CGF.Builder.CreateLoad(field);
value->setAlignment(Alignment.getQuantity());
CGF.EmitARCRelease(value, /*precise*/ false);
}
void profileImpl(llvm::FoldingSetNodeID &id) const {
// 1 is distinguishable from all pointers and byref flags
id.AddInteger(1);
}
};
/// Emits the copy/dispose helpers for an ARC __block __strong
/// variable that's of block-pointer type.
class ARCStrongBlockByrefHelpers : public CodeGenModule::ByrefHelpers {
public:
ARCStrongBlockByrefHelpers(CharUnits alignment) : ByrefHelpers(alignment) {}
void emitCopy(CodeGenFunction &CGF, llvm::Value *destField,
llvm::Value *srcField) {
// Do the copy with objc_retainBlock; that's all that
// _Block_object_assign would do anyway, and we'd have to pass the
// right arguments to make sure it doesn't get no-op'ed.
llvm::LoadInst *oldValue = CGF.Builder.CreateLoad(srcField);
oldValue->setAlignment(Alignment.getQuantity());
llvm::Value *copy = CGF.EmitARCRetainBlock(oldValue, /*mandatory*/ true);
llvm::StoreInst *store = CGF.Builder.CreateStore(copy, destField);
store->setAlignment(Alignment.getQuantity());
}
void emitDispose(CodeGenFunction &CGF, llvm::Value *field) {
llvm::LoadInst *value = CGF.Builder.CreateLoad(field);
value->setAlignment(Alignment.getQuantity());
CGF.EmitARCRelease(value, /*precise*/ false);
}
void profileImpl(llvm::FoldingSetNodeID &id) const {
// 2 is distinguishable from all pointers and byref flags
id.AddInteger(2);
}
};
/// Emits the copy/dispose helpers for a __block variable with a
/// nontrivial copy constructor or destructor.
class CXXByrefHelpers : public CodeGenModule::ByrefHelpers {
QualType VarType;
const Expr *CopyExpr;
public:
CXXByrefHelpers(CharUnits alignment, QualType type,
const Expr *copyExpr)
: ByrefHelpers(alignment), VarType(type), CopyExpr(copyExpr) {}
bool needsCopy() const { return CopyExpr != 0; }
void emitCopy(CodeGenFunction &CGF, llvm::Value *destField,
llvm::Value *srcField) {
if (!CopyExpr) return;
CGF.EmitSynthesizedCXXCopyCtor(destField, srcField, CopyExpr);
}
void emitDispose(CodeGenFunction &CGF, llvm::Value *field) {
EHScopeStack::stable_iterator cleanupDepth = CGF.EHStack.stable_begin();
CGF.PushDestructorCleanup(VarType, field);
CGF.PopCleanupBlocks(cleanupDepth);
}
void profileImpl(llvm::FoldingSetNodeID &id) const {
id.AddPointer(VarType.getCanonicalType().getAsOpaquePtr());
}
};
} // end anonymous namespace
static llvm::Constant *
generateByrefCopyHelper(CodeGenFunction &CGF,
llvm::StructType &byrefType,
CodeGenModule::ByrefHelpers &byrefInfo) {
ASTContext &Context = CGF.getContext();
QualType R = Context.VoidTy;
FunctionArgList args;
ImplicitParamDecl dst(0, SourceLocation(), 0, Context.VoidPtrTy);
args.push_back(&dst);
ImplicitParamDecl src(0, SourceLocation(), 0, Context.VoidPtrTy);
args.push_back(&src);
const CGFunctionInfo &FI =
CGF.CGM.getTypes().arrangeFunctionDeclaration(R, args,
FunctionType::ExtInfo(),
/*variadic*/ false);
CodeGenTypes &Types = CGF.CGM.getTypes();
llvm::FunctionType *LTy = Types.GetFunctionType(FI);
// FIXME: We'd like to put these into a mergable by content, with
// internal linkage.
llvm::Function *Fn =
llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
"__Block_byref_object_copy_", &CGF.CGM.getModule());
IdentifierInfo *II
= &Context.Idents.get("__Block_byref_object_copy_");
FunctionDecl *FD = FunctionDecl::Create(Context,
Context.getTranslationUnitDecl(),
SourceLocation(),
SourceLocation(), II, R, 0,
SC_Static,
SC_None,
false, false);
CGF.StartFunction(FD, R, Fn, FI, args, SourceLocation());
if (byrefInfo.needsCopy()) {
llvm::Type *byrefPtrType = byrefType.getPointerTo(0);
// dst->x
llvm::Value *destField = CGF.GetAddrOfLocalVar(&dst);
destField = CGF.Builder.CreateLoad(destField);
destField = CGF.Builder.CreateBitCast(destField, byrefPtrType);
destField = CGF.Builder.CreateStructGEP(destField, 6, "x");
// src->x
llvm::Value *srcField = CGF.GetAddrOfLocalVar(&src);
srcField = CGF.Builder.CreateLoad(srcField);
srcField = CGF.Builder.CreateBitCast(srcField, byrefPtrType);
srcField = CGF.Builder.CreateStructGEP(srcField, 6, "x");
byrefInfo.emitCopy(CGF, destField, srcField);
}
CGF.FinishFunction();
return llvm::ConstantExpr::getBitCast(Fn, CGF.Int8PtrTy);
}
/// Build the copy helper for a __block variable.
static llvm::Constant *buildByrefCopyHelper(CodeGenModule &CGM,
llvm::StructType &byrefType,
CodeGenModule::ByrefHelpers &info) {
CodeGenFunction CGF(CGM);
return generateByrefCopyHelper(CGF, byrefType, info);
}
/// Generate code for a __block variable's dispose helper.
static llvm::Constant *
generateByrefDisposeHelper(CodeGenFunction &CGF,
llvm::StructType &byrefType,
CodeGenModule::ByrefHelpers &byrefInfo) {
ASTContext &Context = CGF.getContext();
QualType R = Context.VoidTy;
FunctionArgList args;
ImplicitParamDecl src(0, SourceLocation(), 0, Context.VoidPtrTy);
args.push_back(&src);
const CGFunctionInfo &FI =
CGF.CGM.getTypes().arrangeFunctionDeclaration(R, args,
FunctionType::ExtInfo(),
/*variadic*/ false);
CodeGenTypes &Types = CGF.CGM.getTypes();
llvm::FunctionType *LTy = Types.GetFunctionType(FI);
// FIXME: We'd like to put these into a mergable by content, with
// internal linkage.
llvm::Function *Fn =
llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
"__Block_byref_object_dispose_",
&CGF.CGM.getModule());
IdentifierInfo *II
= &Context.Idents.get("__Block_byref_object_dispose_");
FunctionDecl *FD = FunctionDecl::Create(Context,
Context.getTranslationUnitDecl(),
SourceLocation(),
SourceLocation(), II, R, 0,
SC_Static,
SC_None,
false, false);
CGF.StartFunction(FD, R, Fn, FI, args, SourceLocation());
if (byrefInfo.needsDispose()) {
llvm::Value *V = CGF.GetAddrOfLocalVar(&src);
V = CGF.Builder.CreateLoad(V);
V = CGF.Builder.CreateBitCast(V, byrefType.getPointerTo(0));
V = CGF.Builder.CreateStructGEP(V, 6, "x");
byrefInfo.emitDispose(CGF, V);
}
CGF.FinishFunction();
return llvm::ConstantExpr::getBitCast(Fn, CGF.Int8PtrTy);
}
/// Build the dispose helper for a __block variable.
static llvm::Constant *buildByrefDisposeHelper(CodeGenModule &CGM,
llvm::StructType &byrefType,
CodeGenModule::ByrefHelpers &info) {
CodeGenFunction CGF(CGM);
return generateByrefDisposeHelper(CGF, byrefType, info);
}
///
template <class T> static T *buildByrefHelpers(CodeGenModule &CGM,
llvm::StructType &byrefTy,
T &byrefInfo) {
// Increase the field's alignment to be at least pointer alignment,
// since the layout of the byref struct will guarantee at least that.
byrefInfo.Alignment = std::max(byrefInfo.Alignment,
CharUnits::fromQuantity(CGM.PointerAlignInBytes));
llvm::FoldingSetNodeID id;
byrefInfo.Profile(id);
void *insertPos;
CodeGenModule::ByrefHelpers *node
= CGM.ByrefHelpersCache.FindNodeOrInsertPos(id, insertPos);
if (node) return static_cast<T*>(node);
byrefInfo.CopyHelper = buildByrefCopyHelper(CGM, byrefTy, byrefInfo);
byrefInfo.DisposeHelper = buildByrefDisposeHelper(CGM, byrefTy, byrefInfo);
T *copy = new (CGM.getContext()) T(byrefInfo);
CGM.ByrefHelpersCache.InsertNode(copy, insertPos);
return copy;
}
CodeGenModule::ByrefHelpers *
CodeGenFunction::buildByrefHelpers(llvm::StructType &byrefType,
const AutoVarEmission &emission) {
const VarDecl &var = *emission.Variable;
QualType type = var.getType();
if (const CXXRecordDecl *record = type->getAsCXXRecordDecl()) {
const Expr *copyExpr = CGM.getContext().getBlockVarCopyInits(&var);
if (!copyExpr && record->hasTrivialDestructor()) return 0;
CXXByrefHelpers byrefInfo(emission.Alignment, type, copyExpr);
return ::buildByrefHelpers(CGM, byrefType, byrefInfo);
}
// Otherwise, if we don't have a retainable type, there's nothing to do.
// that the runtime does extra copies.
if (!type->isObjCRetainableType()) return 0;
Qualifiers qs = type.getQualifiers();
// If we have lifetime, that dominates.
if (Qualifiers::ObjCLifetime lifetime = qs.getObjCLifetime()) {
assert(getLangOpts().ObjCAutoRefCount);
switch (lifetime) {
case Qualifiers::OCL_None: llvm_unreachable("impossible");
// These are just bits as far as the runtime is concerned.
case Qualifiers::OCL_ExplicitNone:
case Qualifiers::OCL_Autoreleasing:
return 0;
// Tell the runtime that this is ARC __weak, called by the
// byref routines.
case Qualifiers::OCL_Weak: {
ARCWeakByrefHelpers byrefInfo(emission.Alignment);
return ::buildByrefHelpers(CGM, byrefType, byrefInfo);
}
// ARC __strong __block variables need to be retained.
case Qualifiers::OCL_Strong:
// Block pointers need to be copied, and there's no direct
// transfer possible.
if (type->isBlockPointerType()) {
ARCStrongBlockByrefHelpers byrefInfo(emission.Alignment);
return ::buildByrefHelpers(CGM, byrefType, byrefInfo);
// Otherwise, we transfer ownership of the retain from the stack
// to the heap.
} else {
ARCStrongByrefHelpers byrefInfo(emission.Alignment);
return ::buildByrefHelpers(CGM, byrefType, byrefInfo);
}
}
llvm_unreachable("fell out of lifetime switch!");
}
BlockFieldFlags flags;
if (type->isBlockPointerType()) {
flags |= BLOCK_FIELD_IS_BLOCK;
} else if (CGM.getContext().isObjCNSObjectType(type) ||
type->isObjCObjectPointerType()) {
flags |= BLOCK_FIELD_IS_OBJECT;
} else {
return 0;
}
if (type.isObjCGCWeak())
flags |= BLOCK_FIELD_IS_WEAK;
ObjectByrefHelpers byrefInfo(emission.Alignment, flags);
return ::buildByrefHelpers(CGM, byrefType, byrefInfo);
}
unsigned CodeGenFunction::getByRefValueLLVMField(const ValueDecl *VD) const {
assert(ByRefValueInfo.count(VD) && "Did not find value!");
return ByRefValueInfo.find(VD)->second.second;
}
llvm::Value *CodeGenFunction::BuildBlockByrefAddress(llvm::Value *BaseAddr,
const VarDecl *V) {
llvm::Value *Loc = Builder.CreateStructGEP(BaseAddr, 1, "forwarding");
Loc = Builder.CreateLoad(Loc);
Loc = Builder.CreateStructGEP(Loc, getByRefValueLLVMField(V),
V->getNameAsString());
return Loc;
}
/// BuildByRefType - This routine changes a __block variable declared as T x
/// into:
///
/// struct {
/// void *__isa;
/// void *__forwarding;
/// int32_t __flags;
/// int32_t __size;
/// void *__copy_helper; // only if needed
/// void *__destroy_helper; // only if needed
/// char padding[X]; // only if needed
/// T x;
/// } x
///
llvm::Type *CodeGenFunction::BuildByRefType(const VarDecl *D) {
std::pair<llvm::Type *, unsigned> &Info = ByRefValueInfo[D];
if (Info.first)
return Info.first;
QualType Ty = D->getType();
SmallVector<llvm::Type *, 8> types;
llvm::StructType *ByRefType =
llvm::StructType::create(getLLVMContext(),
"struct.__block_byref_" + D->getNameAsString());
// void *__isa;
types.push_back(Int8PtrTy);
// void *__forwarding;
types.push_back(llvm::PointerType::getUnqual(ByRefType));
// int32_t __flags;
types.push_back(Int32Ty);
// int32_t __size;
types.push_back(Int32Ty);
bool HasCopyAndDispose =
(Ty->isObjCRetainableType()) || getContext().getBlockVarCopyInits(D);
if (HasCopyAndDispose) {
/// void *__copy_helper;
types.push_back(Int8PtrTy);
/// void *__destroy_helper;
types.push_back(Int8PtrTy);
}
bool Packed = false;
CharUnits Align = getContext().getDeclAlign(D);
if (Align > getContext().toCharUnitsFromBits(Target.getPointerAlign(0))) {
// We have to insert padding.
// The struct above has 2 32-bit integers.
unsigned CurrentOffsetInBytes = 4 * 2;
// And either 2 or 4 pointers.
CurrentOffsetInBytes += (HasCopyAndDispose ? 4 : 2) *
CGM.getTargetData().getTypeAllocSize(Int8PtrTy);
// Align the offset.
unsigned AlignedOffsetInBytes =
llvm::RoundUpToAlignment(CurrentOffsetInBytes, Align.getQuantity());
unsigned NumPaddingBytes = AlignedOffsetInBytes - CurrentOffsetInBytes;
if (NumPaddingBytes > 0) {
llvm::Type *Ty = Int8Ty;
// FIXME: We need a sema error for alignment larger than the minimum of
// the maximal stack alignment and the alignment of malloc on the system.
if (NumPaddingBytes > 1)
Ty = llvm::ArrayType::get(Ty, NumPaddingBytes);
types.push_back(Ty);
// We want a packed struct.
Packed = true;
}
}
// T x;
types.push_back(ConvertTypeForMem(Ty));
ByRefType->setBody(types, Packed);
Info.first = ByRefType;
Info.second = types.size() - 1;
return Info.first;
}
/// Initialize the structural components of a __block variable, i.e.
/// everything but the actual object.
void CodeGenFunction::emitByrefStructureInit(const AutoVarEmission &emission) {
// Find the address of the local.
llvm::Value *addr = emission.Address;
// That's an alloca of the byref structure type.
llvm::StructType *byrefType = cast<llvm::StructType>(
cast<llvm::PointerType>(addr->getType())->getElementType());
// Build the byref helpers if necessary. This is null if we don't need any.
CodeGenModule::ByrefHelpers *helpers =
buildByrefHelpers(*byrefType, emission);
const VarDecl &D = *emission.Variable;
QualType type = D.getType();
llvm::Value *V;
// Initialize the 'isa', which is just 0 or 1.
int isa = 0;
if (type.isObjCGCWeak())
isa = 1;
V = Builder.CreateIntToPtr(Builder.getInt32(isa), Int8PtrTy, "isa");
Builder.CreateStore(V, Builder.CreateStructGEP(addr, 0, "byref.isa"));
// Store the address of the variable into its own forwarding pointer.
Builder.CreateStore(addr,
Builder.CreateStructGEP(addr, 1, "byref.forwarding"));
// 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,
BlockFlags flags;
if (helpers) flags |= BLOCK_HAS_COPY_DISPOSE;
Builder.CreateStore(llvm::ConstantInt::get(IntTy, flags.getBitMask()),
Builder.CreateStructGEP(addr, 2, "byref.flags"));
CharUnits byrefSize = CGM.GetTargetTypeStoreSize(byrefType);
V = llvm::ConstantInt::get(IntTy, byrefSize.getQuantity());
Builder.CreateStore(V, Builder.CreateStructGEP(addr, 3, "byref.size"));
if (helpers) {
llvm::Value *copy_helper = Builder.CreateStructGEP(addr, 4);
Builder.CreateStore(helpers->CopyHelper, copy_helper);
llvm::Value *destroy_helper = Builder.CreateStructGEP(addr, 5);
Builder.CreateStore(helpers->DisposeHelper, destroy_helper);
}
}
void CodeGenFunction::BuildBlockRelease(llvm::Value *V, BlockFieldFlags flags) {
llvm::Value *F = CGM.getBlockObjectDispose();
llvm::Value *N;
V = Builder.CreateBitCast(V, Int8PtrTy);
N = llvm::ConstantInt::get(Int32Ty, flags.getBitMask());
Builder.CreateCall2(F, V, N);
}
namespace {
struct CallBlockRelease : EHScopeStack::Cleanup {
llvm::Value *Addr;
CallBlockRelease(llvm::Value *Addr) : Addr(Addr) {}
void Emit(CodeGenFunction &CGF, Flags flags) {
// Should we be passing FIELD_IS_WEAK here?
CGF.BuildBlockRelease(Addr, BLOCK_FIELD_IS_BYREF);
}
};
}
/// Enter a cleanup to destroy a __block variable. Note that this
/// cleanup should be a no-op if the variable hasn't left the stack
/// yet; if a cleanup is required for the variable itself, that needs
/// to be done externally.
void CodeGenFunction::enterByrefCleanup(const AutoVarEmission &emission) {
// We don't enter this cleanup if we're in pure-GC mode.
if (CGM.getLangOpts().getGC() == LangOptions::GCOnly)
return;
EHStack.pushCleanup<CallBlockRelease>(NormalAndEHCleanup, emission.Address);
}
/// Adjust the declaration of something from the blocks API.
static void configureBlocksRuntimeObject(CodeGenModule &CGM,
llvm::Constant *C) {
if (!CGM.getLangOpts().BlocksRuntimeOptional) return;
llvm::GlobalValue *GV = cast<llvm::GlobalValue>(C->stripPointerCasts());
if (GV->isDeclaration() &&
GV->getLinkage() == llvm::GlobalValue::ExternalLinkage)
GV->setLinkage(llvm::GlobalValue::ExternalWeakLinkage);
}
llvm::Constant *CodeGenModule::getBlockObjectDispose() {
if (BlockObjectDispose)
return BlockObjectDispose;
llvm::Type *args[] = { Int8PtrTy, Int32Ty };
llvm::FunctionType *fty
= llvm::FunctionType::get(VoidTy, args, false);
BlockObjectDispose = CreateRuntimeFunction(fty, "_Block_object_dispose");
configureBlocksRuntimeObject(*this, BlockObjectDispose);
return BlockObjectDispose;
}
llvm::Constant *CodeGenModule::getBlockObjectAssign() {
if (BlockObjectAssign)
return BlockObjectAssign;
llvm::Type *args[] = { Int8PtrTy, Int8PtrTy, Int32Ty };
llvm::FunctionType *fty
= llvm::FunctionType::get(VoidTy, args, false);
BlockObjectAssign = CreateRuntimeFunction(fty, "_Block_object_assign");
configureBlocksRuntimeObject(*this, BlockObjectAssign);
return BlockObjectAssign;
}
llvm::Constant *CodeGenModule::getNSConcreteGlobalBlock() {
if (NSConcreteGlobalBlock)
return NSConcreteGlobalBlock;
NSConcreteGlobalBlock = GetOrCreateLLVMGlobal("_NSConcreteGlobalBlock",
Int8PtrTy->getPointerTo(), 0);
configureBlocksRuntimeObject(*this, NSConcreteGlobalBlock);
return NSConcreteGlobalBlock;
}
llvm::Constant *CodeGenModule::getNSConcreteStackBlock() {
if (NSConcreteStackBlock)
return NSConcreteStackBlock;
NSConcreteStackBlock = GetOrCreateLLVMGlobal("_NSConcreteStackBlock",
Int8PtrTy->getPointerTo(), 0);
configureBlocksRuntimeObject(*this, NSConcreteStackBlock);
return NSConcreteStackBlock;
}