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llvm-project/clang/lib/CodeGen/CGBlocks.cpp
Akira Hatanaka d542ccfc97 [CodeGen][ObjC] Block captures should inherit the type of the captured 
field in the enclosing lambda or block.

This patch fixes a bug in code-gen where it uses the type of the
declared variable rather than the type of the capture of the enclosing
lambda or block for the block capture. For example, in the following
function, code-gen currently uses i32* for the block capture "a" because
"a" is passed to foo1 as a reference, but it should use i32 since the
enclosing lambda captures "a" by value.

void foo1(int &a) {
  auto lambda = [a]{
    auto block1 = ^{
      i = a;
    };
    block1();
  };
  lambda();
}

rdar://problem/18586386

Differential Revision: https://reviews.llvm.org/D21104

llvm-svn: 281682
2016-09-16 00:02:06 +00:00

2386 lines
86 KiB
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//===--- CGBlocks.cpp - Emit LLVM Code for declarations ---------*- C++ -*-===//
//
// 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 "CGBlocks.h"
#include "CGDebugInfo.h"
#include "CGObjCRuntime.h"
#include "CodeGenFunction.h"
#include "CodeGenModule.h"
#include "clang/AST/DeclObjC.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Module.h"
#include <algorithm>
#include <cstdio>
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), HasCapturedVariableLayout(false),
LocalAddress(Address::invalid()), StructureType(nullptr), Block(block),
DominatingIP(nullptr) {
// 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.
BlockByrefHelpers::~BlockByrefHelpers() {}
/// 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 dispose of a block.
static llvm::Constant *buildDisposeHelper(CodeGenModule &CGM,
const CGBlockInfo &blockInfo) {
return CodeGenFunction(CGM).GenerateDestroyHelperFunction(blockInfo);
}
/// buildBlockDescriptor - Build the block descriptor meta-data for a block.
/// buildBlockDescriptor is accessed from 5th field of the Block_literal
/// meta-data and contains stationary information about the block literal.
/// Its definition will have 4 (or optinally 6) words.
/// \code
/// struct Block_descriptor {
/// unsigned long reserved;
/// unsigned long size; // size of Block_literal metadata in bytes.
/// void *copy_func_helper_decl; // optional copy helper.
/// void *destroy_func_decl; // optioanl destructor helper.
/// void *block_method_encoding_address; // @encode for block literal signature.
/// void *block_layout_info; // encoding of captured block variables.
/// };
/// \endcode
static llvm::Constant *buildBlockDescriptor(CodeGenModule &CGM,
const CGBlockInfo &blockInfo) {
ASTContext &C = CGM.getContext();
llvm::Type *ulong = CGM.getTypes().ConvertType(C.UnsignedLongTy);
llvm::Type *i8p = nullptr;
if (CGM.getLangOpts().OpenCL)
i8p =
llvm::Type::getInt8PtrTy(
CGM.getLLVMContext(), C.getTargetAddressSpace(LangAS::opencl_constant));
else
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).getPointer(), i8p));
// GC layout.
if (C.getLangOpts().ObjC1) {
if (CGM.getLangOpts().getGC() != LangOptions::NonGC)
elements.push_back(CGM.getObjCRuntime().BuildGCBlockLayout(CGM, blockInfo));
else
elements.push_back(CGM.getObjCRuntime().BuildRCBlockLayout(CGM, blockInfo));
}
else
elements.push_back(llvm::Constant::getNullValue(i8p));
llvm::Constant *init = llvm::ConstantStruct::getAnon(elements);
unsigned AddrSpace = 0;
if (C.getLangOpts().OpenCL)
AddrSpace = C.getTargetAddressSpace(LangAS::opencl_constant);
llvm::GlobalVariable *global =
new llvm::GlobalVariable(CGM.getModule(), init->getType(), true,
llvm::GlobalValue::InternalLinkage,
init, "__block_descriptor_tmp", nullptr,
llvm::GlobalValue::NotThreadLocal,
AddrSpace);
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;
Qualifiers::ObjCLifetime Lifetime;
const BlockDecl::Capture *Capture; // null for 'this'
llvm::Type *Type;
QualType FieldType;
BlockLayoutChunk(CharUnits align, CharUnits size,
Qualifiers::ObjCLifetime lifetime,
const BlockDecl::Capture *capture,
llvm::Type *type, QualType fieldType)
: Alignment(align), Size(size), Lifetime(lifetime),
Capture(capture), Type(type), FieldType(fieldType) {}
/// Tell the block info that this chunk has the given field index.
void setIndex(CGBlockInfo &info, unsigned index, CharUnits offset) {
if (!Capture) {
info.CXXThisIndex = index;
info.CXXThisOffset = offset;
} else {
auto C = CGBlockInfo::Capture::makeIndex(index, offset, FieldType);
info.Captures.insert({Capture->getVariable(), C});
}
}
};
/// Order by 1) all __strong together 2) next, all byfref together 3) next,
/// all __weak together. Preserve descending alignment in all situations.
bool operator<(const BlockLayoutChunk &left, const BlockLayoutChunk &right) {
if (left.Alignment != right.Alignment)
return left.Alignment > right.Alignment;
auto getPrefOrder = [](const BlockLayoutChunk &chunk) {
if (chunk.Capture && chunk.Capture->isByRef())
return 1;
if (chunk.Lifetime == Qualifiers::OCL_Strong)
return 0;
if (chunk.Lifetime == Qualifiers::OCL_Weak)
return 2;
return 3;
};
return getPrefOrder(left) < getPrefOrder(right);
}
} // end anonymous namespace
/// 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 auto *record = cast<CXXRecordDecl>(recordType->getDecl());
// Maintain semantics for classes with non-trivial dtors or copy ctors.
if (!record->hasTrivialDestructor()) return false;
if (record->hasNonTrivialCopyConstructor()) 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) {
// Return if this is a function paramter. We shouldn't try to
// rematerialize default arguments of function parameters.
if (isa<ParmVarDecl>(var))
return nullptr;
QualType type = var->getType();
// We can only do this if the variable is const.
if (!type.isConstQualified()) return nullptr;
// 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 nullptr;
// 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 nullptr;
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) {
// The header is basically 'struct { void *; int; int; void *; void *; }'.
// Assert that that struct is packed.
assert(CGM.getIntSize() <= CGM.getPointerSize());
assert(CGM.getIntAlign() <= CGM.getPointerAlign());
assert((2 * CGM.getIntSize()).isMultipleOf(CGM.getPointerAlign()));
info.BlockAlign = CGM.getPointerAlign();
info.BlockSize = 3 * CGM.getPointerSize() + 2 * CGM.getIntSize();
assert(elementTypes.empty());
elementTypes.push_back(CGM.VoidPtrTy);
elementTypes.push_back(CGM.IntTy);
elementTypes.push_back(CGM.IntTy);
elementTypes.push_back(CGM.VoidPtrTy);
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;
}
else if (C.getLangOpts().ObjC1 &&
CGM.getLangOpts().getGC() == LangOptions::NonGC)
info.HasCapturedVariableLayout = true;
// 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()) {
assert(CGF && CGF->CurFuncDecl && isa<CXXMethodDecl>(CGF->CurFuncDecl) &&
"Can't capture 'this' outside a method");
QualType thisType = cast<CXXMethodDecl>(CGF->CurFuncDecl)->getThisType(C);
// Theoretically, this could be in a different address space, so
// don't assume standard pointer size/align.
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,
Qualifiers::OCL_None,
nullptr, llvmType, thisType));
}
// Next, all the block captures.
for (const auto &CI : block->captures()) {
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.
CharUnits align = CGM.getPointerAlign();
maxFieldAlign = std::max(maxFieldAlign, align);
layout.push_back(BlockLayoutChunk(align, CGM.getPointerSize(),
Qualifiers::OCL_None, &CI,
CGM.VoidPtrTy, variable->getType()));
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.
Qualifiers::ObjCLifetime lifetime =
variable->getType().getObjCLifetime();
if (lifetime) {
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()) {
// But honor the inert __unsafe_unretained qualifier, which doesn't
// actually make it into the type system.
if (variable->getType()->isObjCInertUnsafeUnretainedType()) {
lifetime = Qualifiers::OCL_ExplicitNone;
} else {
info.NeedsCopyDispose = true;
// used for mrr below.
lifetime = Qualifiers::OCL_Strong;
}
// 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();
// If the variable is captured by an enclosing block or lambda expression,
// use the type of the capture field.
if (CGF->BlockInfo && CI.isNested())
VT = CGF->BlockInfo->getCapture(variable).fieldType();
else if (auto *FD = CGF->LambdaCaptureFields.lookup(variable))
VT = FD->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, lifetime, &CI, llvmType, VT));
}
// 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());
// Needed for blocks layout info.
info.BlockHeaderForcedGapOffset = info.BlockSize;
info.BlockHeaderForcedGapSize = CharUnits::Zero();
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(), blockSize);
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);
}
}
assert(endAlign == getLowBit(blockSize));
// At this point, we just have to add padding if the end align still
// isn't aligned right.
if (endAlign < maxFieldAlign) {
CharUnits newBlockSize = blockSize.alignTo(maxFieldAlign);
CharUnits padding = newBlockSize - blockSize;
// If we haven't yet added any fields, remember that there was an
// initial gap; this need to go into the block layout bit map.
if (blockSize == info.BlockHeaderForcedGapOffset) {
info.BlockHeaderForcedGapSize = padding;
}
elementTypes.push_back(llvm::ArrayType::get(CGM.Int8Ty,
padding.getQuantity()));
blockSize = newBlockSize;
endAlign = getLowBit(blockSize); // might be > maxFieldAlign
}
assert(endAlign >= maxFieldAlign);
assert(endAlign == getLowBit(blockSize));
// 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) {
if (endAlign < li->Alignment) {
// size may not be multiple of alignment. This can only happen with
// an over-aligned variable. We will be adding a padding field to
// make the size be multiple of alignment.
CharUnits padding = li->Alignment - endAlign;
elementTypes.push_back(llvm::ArrayType::get(CGM.Int8Ty,
padding.getQuantity()));
blockSize += padding;
endAlign = getLowBit(blockSize);
}
assert(endAlign >= li->Alignment);
li->setIndex(info, elementTypes.size(), blockSize);
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.LocalAddress = CGF.CreateTempAlloca(blockInfo.StructureType,
blockInfo.BlockAlign, "block");
// 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 (const auto &CI : block->captures()) {
// 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.
Address addr = CGF.Builder.CreateStructGEP(blockInfo.LocalAddress,
capture.getIndex(),
capture.getOffset());
// We can use that GEP as the dominating IP.
if (!blockInfo.DominatingIP)
blockInfo.DominatingIP = cast<llvm::Instruction>(addr.getPointer());
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 != nullptr);
}
/// 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.
std::unique_ptr<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, true).GenerateBlockFunction(CurGD, blockInfo,
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);
Address blockAddr = blockInfo.LocalAddress;
assert(blockAddr.isValid() && "block has no address!");
// Compute the initial on-stack block flags.
BlockFlags flags = BLOCK_HAS_SIGNATURE;
if (blockInfo.HasCapturedVariableLayout) flags |= BLOCK_HAS_EXTENDED_LAYOUT;
if (blockInfo.NeedsCopyDispose) flags |= BLOCK_HAS_COPY_DISPOSE;
if (blockInfo.HasCXXObject) flags |= BLOCK_HAS_CXX_OBJ;
if (blockInfo.UsesStret) flags |= BLOCK_USE_STRET;
auto projectField =
[&](unsigned index, CharUnits offset, const Twine &name) -> Address {
return Builder.CreateStructGEP(blockAddr, index, offset, name);
};
auto storeField =
[&](llvm::Value *value, unsigned index, CharUnits offset,
const Twine &name) {
Builder.CreateStore(value, projectField(index, offset, name));
};
// Initialize the block header.
{
// We assume all the header fields are densely packed.
unsigned index = 0;
CharUnits offset;
auto addHeaderField =
[&](llvm::Value *value, CharUnits size, const Twine &name) {
storeField(value, index, offset, name);
offset += size;
index++;
};
addHeaderField(isa, getPointerSize(), "block.isa");
addHeaderField(llvm::ConstantInt::get(IntTy, flags.getBitMask()),
getIntSize(), "block.flags");
addHeaderField(llvm::ConstantInt::get(IntTy, 0),
getIntSize(), "block.reserved");
addHeaderField(blockFn, getPointerSize(), "block.invoke");
addHeaderField(descriptor, getPointerSize(), "block.descriptor");
}
// Finally, capture all the values into the block.
const BlockDecl *blockDecl = blockInfo.getBlockDecl();
// First, 'this'.
if (blockDecl->capturesCXXThis()) {
Address addr = projectField(blockInfo.CXXThisIndex, blockInfo.CXXThisOffset,
"block.captured-this.addr");
Builder.CreateStore(LoadCXXThis(), addr);
}
// Next, captured variables.
for (const auto &CI : blockDecl->captures()) {
const VarDecl *variable = CI.getVariable();
const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
// Ignore constant captures.
if (capture.isConstant()) continue;
QualType type = capture.fieldType();
// This will be a [[type]]*, except that a byref entry will just be
// an i8**.
Address blockField =
projectField(capture.getIndex(), capture.getOffset(), "block.captured");
// Compute the address of the thing we're going to move into the
// block literal.
Address src = Address::invalid();
if (blockDecl->isConversionFromLambda()) {
// The lambda capture in a lambda's conversion-to-block-pointer is
// special; we'll simply emit it directly.
src = Address::invalid();
} else if (CI.isByRef()) {
if (BlockInfo && 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(),
enclosingCapture.getOffset(),
"block.capture.addr");
} else {
auto I = LocalDeclMap.find(variable);
assert(I != LocalDeclMap.end());
src = I->second;
}
} else {
DeclRefExpr declRef(const_cast<VarDecl *>(variable),
/*RefersToEnclosingVariableOrCapture*/ CI.isNested(),
type.getNonReferenceType(), VK_LValue,
SourceLocation());
src = EmitDeclRefLValue(&declRef).getAddress();
};
// 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.
llvm::Value *byrefPointer;
if (CI.isNested())
byrefPointer = Builder.CreateLoad(src, "byref.capture");
else
byrefPointer = Builder.CreateBitCast(src.getPointer(), VoidPtrTy);
// Write that void* into the capture field.
Builder.CreateStore(byrefPointer, 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.
AggValueSlot Slot =
AggValueSlot::forAddr(blockField, 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(src.getPointer(), blockField);
// If this is an ARC __strong block-pointer variable, don't do a
// block copy.
//
// TODO: this can be generalized into the normal initialization logic:
// we should never need to do a block-copy when initializing a local
// variable, because the local variable's lifetime should be strictly
// contained within the stack block's.
} else if (type.getObjCLifetime() == Qualifiers::OCL_Strong &&
type->isBlockPointerType()) {
// Load the block and do a simple retain.
llvm::Value *value = Builder.CreateLoad(src, "block.captured_block");
value = EmitARCRetainNonBlock(value);
// Do a primitive store to the block field.
Builder.CreateStore(value, 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(getContext(), /*DC*/ nullptr,
SourceLocation(), /*name*/ nullptr,
type);
// We use one of these or the other depending on whether the
// reference is nested.
DeclRefExpr declRef(const_cast<VarDecl *>(variable),
/*RefersToEnclosingVariableOrCapture*/ CI.isNested(),
type, VK_LValue, SourceLocation());
ImplicitCastExpr l2r(ImplicitCastExpr::OnStack, type, CK_LValueToRValue,
&declRef, VK_RValue);
// FIXME: Pass a specific location for the expr init so that the store is
// attributed to a reasonable location - otherwise it may be attributed to
// locations of subexpressions in the initialization.
EmitExprAsInit(&l2r, &blockFieldPseudoVar,
MakeAddrLValue(blockField, type, AlignmentSource::Decl),
/*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.getPointer(),
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, nullptr);
// Now form a pointer to that.
unsigned AddrSpace = 0;
if (getLangOpts().OpenCL)
AddrSpace = getContext().getTargetAddressSpace(LangAS::opencl_constant);
BlockDescriptorType = llvm::PointerType::get(BlockDescriptorType, AddrSpace);
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, nullptr);
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(CGM.getGenericBlockLiteralType(), 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->arguments());
// Load the function.
llvm::Value *Func = Builder.CreateAlignedLoad(FuncPtr, getPointerAlign());
const FunctionType *FuncTy = FnType->castAs<FunctionType>();
const CGFunctionInfo &FnInfo =
CGM.getTypes().arrangeBlockFunctionCall(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);
}
Address 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.find(variable)->second;
Address addr =
Builder.CreateStructGEP(LoadBlockStruct(), capture.getIndex(),
capture.getOffset(), "block.capture.addr");
if (isByRef) {
// addr should be a void** right now. Load, then cast the result
// to byref*.
auto &byrefInfo = getBlockByrefInfo(variable);
addr = Address(Builder.CreateLoad(addr), byrefInfo.ByrefAlignment);
auto byrefPointerType = llvm::PointerType::get(byrefInfo.Type, 0);
addr = Builder.CreateBitCast(addr, byrefPointerType, "byref.addr");
addr = emitBlockByrefAddress(addr, byrefInfo, /*follow*/ true,
variable->getName());
}
if (auto refType = capture.fieldType()->getAs<ReferenceType>())
addr = EmitLoadOfReference(addr, refType);
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, nullptr, blockInfo);
// Using that metadata, generate the actual block function.
llvm::Constant *blockFn;
{
CodeGenFunction::DeclMapTy LocalDeclMap;
blockFn = CodeGenFunction(*this).GenerateBlockFunction(GlobalDecl(),
blockInfo,
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);
}
void CodeGenFunction::setBlockContextParameter(const ImplicitParamDecl *D,
unsigned argNum,
llvm::Value *arg) {
assert(BlockInfo && "not emitting prologue of block invocation function?!");
llvm::Value *localAddr = nullptr;
if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
// Allocate a stack slot to let the debug info survive the RA.
Address alloc = CreateMemTemp(D->getType(), D->getName() + ".addr");
Builder.CreateStore(arg, alloc);
localAddr = Builder.CreateLoad(alloc);
}
if (CGDebugInfo *DI = getDebugInfo()) {
if (CGM.getCodeGenOpts().getDebugInfo() >=
codegenoptions::LimitedDebugInfo) {
DI->setLocation(D->getLocation());
DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, arg, argNum,
localAddr, Builder);
}
}
SourceLocation StartLoc = BlockInfo->getBlockExpr()->getBody()->getLocStart();
ApplyDebugLocation Scope(*this, StartLoc);
// Instead of messing around with LocalDeclMap, just set the value
// directly as BlockPointer.
BlockPointer = Builder.CreateBitCast(arg,
BlockInfo->StructureType->getPointerTo(),
"block");
}
Address CodeGenFunction::LoadBlockStruct() {
assert(BlockInfo && "not in a block invocation function!");
assert(BlockPointer && "no block pointer set!");
return Address(BlockPointer, BlockInfo->BlockAlign);
}
llvm::Function *
CodeGenFunction::GenerateBlockFunction(GlobalDecl GD,
const CGBlockInfo &blockInfo,
const DeclMapTy &ldm,
bool IsLambdaConversionToBlock) {
const BlockDecl *blockDecl = blockInfo.getBlockDecl();
CurGD = GD;
CurEHLocation = blockInfo.getBlockExpr()->getLocEnd();
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 auto *var = dyn_cast<VarDecl>(i->first);
if (var && !var->hasLocalStorage())
setAddrOfLocalVar(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(getContext(), const_cast<BlockDecl*>(blockDecl),
SourceLocation(), II, selfTy);
args.push_back(&selfDecl);
// Now add the rest of the parameters.
args.append(blockDecl->param_begin(), blockDecl->param_end());
// Create the function declaration.
const FunctionProtoType *fnType = blockInfo.getBlockExpr()->getFunctionType();
const CGFunctionInfo &fnInfo =
CGM.getTypes().arrangeBlockFunctionDeclaration(fnType, args);
if (CGM.ReturnSlotInterferesWithArgs(fnInfo))
blockInfo.UsesStret = true;
llvm::FunctionType *fnLLVMType = CGM.getTypes().GetFunctionType(fnInfo);
StringRef name = CGM.getBlockMangledName(GD, blockDecl);
llvm::Function *fn = llvm::Function::Create(
fnLLVMType, llvm::GlobalValue::InternalLinkage, name, &CGM.getModule());
CGM.SetInternalFunctionAttributes(blockDecl, fn, fnInfo);
// Begin generating the function.
StartFunction(blockDecl, fnType->getReturnType(), fn, fnInfo, args,
blockDecl->getLocation(),
blockInfo.getBlockExpr()->getBody()->getLocStart());
// Okay. Undo some of what StartFunction did.
// At -O0 we generate an explicit alloca for the BlockPointer, so the RA
// won't delete the dbg.declare intrinsics for captured variables.
llvm::Value *BlockPointerDbgLoc = BlockPointer;
if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
// Allocate a stack slot for it, so we can point the debugger to it
Address Alloca = CreateTempAlloca(BlockPointer->getType(),
getPointerAlign(),
"block.addr");
// Set the DebugLocation to empty, so the store is recognized as a
// frame setup instruction by llvm::DwarfDebug::beginFunction().
auto NL = ApplyDebugLocation::CreateEmpty(*this);
Builder.CreateStore(BlockPointer, Alloca);
BlockPointerDbgLoc = Alloca.getPointer();
}
// If we have a C++ 'this' reference, go ahead and force it into
// existence now.
if (blockDecl->capturesCXXThis()) {
Address addr =
Builder.CreateStructGEP(LoadBlockStruct(), blockInfo.CXXThisIndex,
blockInfo.CXXThisOffset, "block.captured-this");
CXXThisValue = Builder.CreateLoad(addr, "this");
}
// Also force all the constant captures.
for (const auto &CI : blockDecl->captures()) {
const VarDecl *variable = CI.getVariable();
const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
if (!capture.isConstant()) continue;
CharUnits align = getContext().getDeclAlign(variable);
Address alloca =
CreateMemTemp(variable->getType(), align, "block.captured-const");
Builder.CreateStore(capture.getConstant(), alloca);
setAddrOfLocalVar(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 {
PGO.assignRegionCounters(GlobalDecl(blockDecl), fn);
incrementProfileCounter(blockDecl->getBody());
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 (const auto &CI : blockDecl->captures()) {
const VarDecl *variable = CI.getVariable();
DI->EmitLocation(Builder, variable->getLocation());
if (CGM.getCodeGenOpts().getDebugInfo() >=
codegenoptions::LimitedDebugInfo) {
const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
if (capture.isConstant()) {
auto addr = LocalDeclMap.find(variable)->second;
DI->EmitDeclareOfAutoVariable(variable, addr.getPointer(),
Builder);
continue;
}
DI->EmitDeclareOfBlockDeclRefVariable(
variable, BlockPointerDbgLoc, Builder, blockInfo,
entry_ptr == entry->end() ? nullptr : &*entry_ptr);
}
}
// Recover location if it was changed in the above loop.
DI->EmitLocation(Builder,
cast<CompoundStmt>(blockDecl->getBody())->getRBracLoc());
}
// And resume where we left off.
if (resume == nullptr)
Builder.ClearInsertionPoint();
else
Builder.SetInsertPoint(resume);
FinishFunction(cast<CompoundStmt>(blockDecl->getBody())->getRBracLoc());
return fn;
}
/*
notes.push_back(HelperInfo());
HelperInfo &note = 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;
}
*/
/// Generate the copy-helper function for a block closure object:
/// static void block_copy_helper(block_t *dst, block_t *src);
/// The runtime will have previously initialized 'dst' by doing a
/// bit-copy of 'src'.
///
/// Note that this copies an entire block closure object to the heap;
/// it should not be confused with a 'byref copy helper', which moves
/// the contents of an individual __block variable to the heap.
llvm::Constant *
CodeGenFunction::GenerateCopyHelperFunction(const CGBlockInfo &blockInfo) {
ASTContext &C = getContext();
FunctionArgList args;
ImplicitParamDecl dstDecl(getContext(), nullptr, SourceLocation(), nullptr,
C.VoidPtrTy);
args.push_back(&dstDecl);
ImplicitParamDecl srcDecl(getContext(), nullptr, SourceLocation(), nullptr,
C.VoidPtrTy);
args.push_back(&srcDecl);
const CGFunctionInfo &FI =
CGM.getTypes().arrangeBuiltinFunctionDeclaration(C.VoidTy, args);
// 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_");
FunctionDecl *FD = FunctionDecl::Create(C,
C.getTranslationUnitDecl(),
SourceLocation(),
SourceLocation(), II, C.VoidTy,
nullptr, SC_Static,
false,
false);
CGM.SetInternalFunctionAttributes(nullptr, Fn, FI);
auto NL = ApplyDebugLocation::CreateEmpty(*this);
StartFunction(FD, C.VoidTy, Fn, FI, args);
// Create a scope with an artificial location for the body of this function.
auto AL = ApplyDebugLocation::CreateArtificial(*this);
llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo();
Address src = GetAddrOfLocalVar(&srcDecl);
src = Address(Builder.CreateLoad(src), blockInfo.BlockAlign);
src = Builder.CreateBitCast(src, structPtrTy, "block.source");
Address dst = GetAddrOfLocalVar(&dstDecl);
dst = Address(Builder.CreateLoad(dst), blockInfo.BlockAlign);
dst = Builder.CreateBitCast(dst, structPtrTy, "block.dest");
const BlockDecl *blockDecl = blockInfo.getBlockDecl();
for (const auto &CI : blockDecl->captures()) {
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 useARCWeakCopy = false;
bool useARCStrongCopy = 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;
bool isBlockPointer = type->isBlockPointerType();
if (isBlockPointer)
flags = BLOCK_FIELD_IS_BLOCK;
// Special rules for ARC captures:
Qualifiers qs = type.getQualifiers();
// We need to register __weak direct captures with the runtime.
if (qs.getObjCLifetime() == Qualifiers::OCL_Weak) {
useARCWeakCopy = true;
// We need to retain the copied value for __strong direct captures.
} else if (qs.getObjCLifetime() == Qualifiers::OCL_Strong) {
// If it's a block pointer, we have to copy the block and
// assign that to the destination pointer, so we might as
// well use _Block_object_assign. Otherwise we can avoid that.
if (!isBlockPointer)
useARCStrongCopy = true;
// Non-ARC captures of retainable pointers are strong and
// therefore require a call to _Block_object_assign.
} else if (!qs.getObjCLifetime() && !getLangOpts().ObjCAutoRefCount) {
// fall through
// Otherwise the memcpy is fine.
} else {
continue;
}
// For all other types, the memcpy is fine.
} else {
continue;
}
unsigned index = capture.getIndex();
Address srcField = Builder.CreateStructGEP(src, index, capture.getOffset());
Address dstField = Builder.CreateStructGEP(dst, index, capture.getOffset());
// If there's an explicit copy expression, we do that.
if (copyExpr) {
EmitSynthesizedCXXCopyCtor(dstField, srcField, copyExpr);
} else if (useARCWeakCopy) {
EmitARCCopyWeak(dstField, srcField);
} else {
llvm::Value *srcValue = Builder.CreateLoad(srcField, "blockcopy.src");
if (useARCStrongCopy) {
// At -O0, store null into the destination field (so that the
// storeStrong doesn't over-release) and then call storeStrong.
// This is a workaround to not having an initStrong call.
if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
auto *ty = cast<llvm::PointerType>(srcValue->getType());
llvm::Value *null = llvm::ConstantPointerNull::get(ty);
Builder.CreateStore(null, dstField);
EmitARCStoreStrongCall(dstField, srcValue, true);
// With optimization enabled, take advantage of the fact that
// the blocks runtime guarantees a memcpy of the block data, and
// just emit a retain of the src field.
} else {
EmitARCRetainNonBlock(srcValue);
// We don't need this anymore, so kill it. It's not quite
// worth the annoyance to avoid creating it in the first place.
cast<llvm::Instruction>(dstField.getPointer())->eraseFromParent();
}
} else {
srcValue = Builder.CreateBitCast(srcValue, VoidPtrTy);
llvm::Value *dstAddr =
Builder.CreateBitCast(dstField.getPointer(), VoidPtrTy);
llvm::Value *args[] = {
dstAddr, srcValue, llvm::ConstantInt::get(Int32Ty, flags.getBitMask())
};
bool copyCanThrow = false;
if (CI.isByRef() && variable->getType()->getAsCXXRecordDecl()) {
const Expr *copyExpr =
CGM.getContext().getBlockVarCopyInits(variable);
if (copyExpr) {
copyCanThrow = true; // FIXME: reuse the noexcept logic
}
}
if (copyCanThrow) {
EmitRuntimeCallOrInvoke(CGM.getBlockObjectAssign(), args);
} else {
EmitNounwindRuntimeCall(CGM.getBlockObjectAssign(), args);
}
}
}
}
FinishFunction();
return llvm::ConstantExpr::getBitCast(Fn, VoidPtrTy);
}
/// Generate the destroy-helper function for a block closure object:
/// static void block_destroy_helper(block_t *theBlock);
///
/// Note that this destroys a heap-allocated block closure object;
/// it should not be confused with a 'byref destroy helper', which
/// destroys the heap-allocated contents of an individual __block
/// variable.
llvm::Constant *
CodeGenFunction::GenerateDestroyHelperFunction(const CGBlockInfo &blockInfo) {
ASTContext &C = getContext();
FunctionArgList args;
ImplicitParamDecl srcDecl(getContext(), nullptr, SourceLocation(), nullptr,
C.VoidPtrTy);
args.push_back(&srcDecl);
const CGFunctionInfo &FI =
CGM.getTypes().arrangeBuiltinFunctionDeclaration(C.VoidTy, args);
// 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());
IdentifierInfo *II
= &CGM.getContext().Idents.get("__destroy_helper_block_");
FunctionDecl *FD = FunctionDecl::Create(C, C.getTranslationUnitDecl(),
SourceLocation(),
SourceLocation(), II, C.VoidTy,
nullptr, SC_Static,
false, false);
CGM.SetInternalFunctionAttributes(nullptr, Fn, FI);
// Create a scope with an artificial location for the body of this function.
auto NL = ApplyDebugLocation::CreateEmpty(*this);
StartFunction(FD, C.VoidTy, Fn, FI, args);
auto AL = ApplyDebugLocation::CreateArtificial(*this);
llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo();
Address src = GetAddrOfLocalVar(&srcDecl);
src = Address(Builder.CreateLoad(src), blockInfo.BlockAlign);
src = Builder.CreateBitCast(src, structPtrTy, "block");
const BlockDecl *blockDecl = blockInfo.getBlockDecl();
CodeGenFunction::RunCleanupsScope cleanups(*this);
for (const auto &CI : blockDecl->captures()) {
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 = nullptr;
bool useARCWeakDestroy = false;
bool useARCStrongDestroy = 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.
Qualifiers qs = type.getQualifiers();
// Use objc_storeStrong for __strong direct captures; the
// dynamic tools really like it when we do this.
if (qs.getObjCLifetime() == Qualifiers::OCL_Strong) {
useARCStrongDestroy = true;
// Support __weak direct captures.
} else if (qs.getObjCLifetime() == Qualifiers::OCL_Weak) {
useARCWeakDestroy = true;
// Non-ARC captures are strong, and we need to use _Block_object_dispose.
} else if (!qs.hasObjCLifetime() && !getLangOpts().ObjCAutoRefCount) {
// fall through
// Otherwise, we have nothing to do.
} else {
continue;
}
} else {
continue;
}
Address srcField =
Builder.CreateStructGEP(src, capture.getIndex(), capture.getOffset());
// 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 (useARCWeakDestroy) {
EmitARCDestroyWeak(srcField);
// Destroy strong objects with a call if requested.
} else if (useARCStrongDestroy) {
EmitARCDestroyStrong(srcField, ARCImpreciseLifetime);
// 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 final : public BlockByrefHelpers {
BlockFieldFlags Flags;
public:
ObjectByrefHelpers(CharUnits alignment, BlockFieldFlags flags)
: BlockByrefHelpers(alignment), Flags(flags) {}
void emitCopy(CodeGenFunction &CGF, Address destField,
Address srcField) override {
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();
llvm::Value *args[] = { destField.getPointer(), srcValue, flagsVal };
CGF.EmitNounwindRuntimeCall(fn, args);
}
void emitDispose(CodeGenFunction &CGF, Address field) override {
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 override {
id.AddInteger(Flags.getBitMask());
}
};
/// Emits the copy/dispose helpers for an ARC __block __weak variable.
class ARCWeakByrefHelpers final : public BlockByrefHelpers {
public:
ARCWeakByrefHelpers(CharUnits alignment) : BlockByrefHelpers(alignment) {}
void emitCopy(CodeGenFunction &CGF, Address destField,
Address srcField) override {
CGF.EmitARCMoveWeak(destField, srcField);
}
void emitDispose(CodeGenFunction &CGF, Address field) override {
CGF.EmitARCDestroyWeak(field);
}
void profileImpl(llvm::FoldingSetNodeID &id) const override {
// 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 final : public BlockByrefHelpers {
public:
ARCStrongByrefHelpers(CharUnits alignment) : BlockByrefHelpers(alignment) {}
void emitCopy(CodeGenFunction &CGF, Address destField,
Address srcField) override {
// Do a "move" by copying the value and then zeroing out the old
// variable.
llvm::Value *value = CGF.Builder.CreateLoad(srcField);
llvm::Value *null =
llvm::ConstantPointerNull::get(cast<llvm::PointerType>(value->getType()));
if (CGF.CGM.getCodeGenOpts().OptimizationLevel == 0) {
CGF.Builder.CreateStore(null, destField);
CGF.EmitARCStoreStrongCall(destField, value, /*ignored*/ true);
CGF.EmitARCStoreStrongCall(srcField, null, /*ignored*/ true);
return;
}
CGF.Builder.CreateStore(value, destField);
CGF.Builder.CreateStore(null, srcField);
}
void emitDispose(CodeGenFunction &CGF, Address field) override {
CGF.EmitARCDestroyStrong(field, ARCImpreciseLifetime);
}
void profileImpl(llvm::FoldingSetNodeID &id) const override {
// 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 final : public BlockByrefHelpers {
public:
ARCStrongBlockByrefHelpers(CharUnits alignment)
: BlockByrefHelpers(alignment) {}
void emitCopy(CodeGenFunction &CGF, Address destField,
Address srcField) override {
// 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::Value *oldValue = CGF.Builder.CreateLoad(srcField);
llvm::Value *copy = CGF.EmitARCRetainBlock(oldValue, /*mandatory*/ true);
CGF.Builder.CreateStore(copy, destField);
}
void emitDispose(CodeGenFunction &CGF, Address field) override {
CGF.EmitARCDestroyStrong(field, ARCImpreciseLifetime);
}
void profileImpl(llvm::FoldingSetNodeID &id) const override {
// 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 final : public BlockByrefHelpers {
QualType VarType;
const Expr *CopyExpr;
public:
CXXByrefHelpers(CharUnits alignment, QualType type,
const Expr *copyExpr)
: BlockByrefHelpers(alignment), VarType(type), CopyExpr(copyExpr) {}
bool needsCopy() const override { return CopyExpr != nullptr; }
void emitCopy(CodeGenFunction &CGF, Address destField,
Address srcField) override {
if (!CopyExpr) return;
CGF.EmitSynthesizedCXXCopyCtor(destField, srcField, CopyExpr);
}
void emitDispose(CodeGenFunction &CGF, Address field) override {
EHScopeStack::stable_iterator cleanupDepth = CGF.EHStack.stable_begin();
CGF.PushDestructorCleanup(VarType, field);
CGF.PopCleanupBlocks(cleanupDepth);
}
void profileImpl(llvm::FoldingSetNodeID &id) const override {
id.AddPointer(VarType.getCanonicalType().getAsOpaquePtr());
}
};
} // end anonymous namespace
static llvm::Constant *
generateByrefCopyHelper(CodeGenFunction &CGF, const BlockByrefInfo &byrefInfo,
BlockByrefHelpers &generator) {
ASTContext &Context = CGF.getContext();
QualType R = Context.VoidTy;
FunctionArgList args;
ImplicitParamDecl dst(CGF.getContext(), nullptr, SourceLocation(), nullptr,
Context.VoidPtrTy);
args.push_back(&dst);
ImplicitParamDecl src(CGF.getContext(), nullptr, SourceLocation(), nullptr,
Context.VoidPtrTy);
args.push_back(&src);
const CGFunctionInfo &FI =
CGF.CGM.getTypes().arrangeBuiltinFunctionDeclaration(R, args);
llvm::FunctionType *LTy = CGF.CGM.getTypes().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, nullptr,
SC_Static,
false, false);
CGF.CGM.SetInternalFunctionAttributes(nullptr, Fn, FI);
CGF.StartFunction(FD, R, Fn, FI, args);
if (generator.needsCopy()) {
llvm::Type *byrefPtrType = byrefInfo.Type->getPointerTo(0);
// dst->x
Address destField = CGF.GetAddrOfLocalVar(&dst);
destField = Address(CGF.Builder.CreateLoad(destField),
byrefInfo.ByrefAlignment);
destField = CGF.Builder.CreateBitCast(destField, byrefPtrType);
destField = CGF.emitBlockByrefAddress(destField, byrefInfo, false,
"dest-object");
// src->x
Address srcField = CGF.GetAddrOfLocalVar(&src);
srcField = Address(CGF.Builder.CreateLoad(srcField),
byrefInfo.ByrefAlignment);
srcField = CGF.Builder.CreateBitCast(srcField, byrefPtrType);
srcField = CGF.emitBlockByrefAddress(srcField, byrefInfo, false,
"src-object");
generator.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,
const BlockByrefInfo &byrefInfo,
BlockByrefHelpers &generator) {
CodeGenFunction CGF(CGM);
return generateByrefCopyHelper(CGF, byrefInfo, generator);
}
/// Generate code for a __block variable's dispose helper.
static llvm::Constant *
generateByrefDisposeHelper(CodeGenFunction &CGF,
const BlockByrefInfo &byrefInfo,
BlockByrefHelpers &generator) {
ASTContext &Context = CGF.getContext();
QualType R = Context.VoidTy;
FunctionArgList args;
ImplicitParamDecl src(CGF.getContext(), nullptr, SourceLocation(), nullptr,
Context.VoidPtrTy);
args.push_back(&src);
const CGFunctionInfo &FI =
CGF.CGM.getTypes().arrangeBuiltinFunctionDeclaration(R, args);
llvm::FunctionType *LTy = CGF.CGM.getTypes().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, nullptr,
SC_Static,
false, false);
CGF.CGM.SetInternalFunctionAttributes(nullptr, Fn, FI);
CGF.StartFunction(FD, R, Fn, FI, args);
if (generator.needsDispose()) {
Address addr = CGF.GetAddrOfLocalVar(&src);
addr = Address(CGF.Builder.CreateLoad(addr), byrefInfo.ByrefAlignment);
auto byrefPtrType = byrefInfo.Type->getPointerTo(0);
addr = CGF.Builder.CreateBitCast(addr, byrefPtrType);
addr = CGF.emitBlockByrefAddress(addr, byrefInfo, false, "object");
generator.emitDispose(CGF, addr);
}
CGF.FinishFunction();
return llvm::ConstantExpr::getBitCast(Fn, CGF.Int8PtrTy);
}
/// Build the dispose helper for a __block variable.
static llvm::Constant *buildByrefDisposeHelper(CodeGenModule &CGM,
const BlockByrefInfo &byrefInfo,
BlockByrefHelpers &generator) {
CodeGenFunction CGF(CGM);
return generateByrefDisposeHelper(CGF, byrefInfo, generator);
}
/// Lazily build the copy and dispose helpers for a __block variable
/// with the given information.
template <class T>
static T *buildByrefHelpers(CodeGenModule &CGM, const BlockByrefInfo &byrefInfo,
T &&generator) {
llvm::FoldingSetNodeID id;
generator.Profile(id);
void *insertPos;
BlockByrefHelpers *node
= CGM.ByrefHelpersCache.FindNodeOrInsertPos(id, insertPos);
if (node) return static_cast<T*>(node);
generator.CopyHelper = buildByrefCopyHelper(CGM, byrefInfo, generator);
generator.DisposeHelper = buildByrefDisposeHelper(CGM, byrefInfo, generator);
T *copy = new (CGM.getContext()) T(std::move(generator));
CGM.ByrefHelpersCache.InsertNode(copy, insertPos);
return copy;
}
/// Build the copy and dispose helpers for the given __block variable
/// emission. Places the helpers in the global cache. Returns null
/// if no helpers are required.
BlockByrefHelpers *
CodeGenFunction::buildByrefHelpers(llvm::StructType &byrefType,
const AutoVarEmission &emission) {
const VarDecl &var = *emission.Variable;
QualType type = var.getType();
auto &byrefInfo = getBlockByrefInfo(&var);
// The alignment we care about for the purposes of uniquing byref
// helpers is the alignment of the actual byref value field.
CharUnits valueAlignment =
byrefInfo.ByrefAlignment.alignmentAtOffset(byrefInfo.FieldOffset);
if (const CXXRecordDecl *record = type->getAsCXXRecordDecl()) {
const Expr *copyExpr = CGM.getContext().getBlockVarCopyInits(&var);
if (!copyExpr && record->hasTrivialDestructor()) return nullptr;
return ::buildByrefHelpers(
CGM, byrefInfo, CXXByrefHelpers(valueAlignment, type, copyExpr));
}
// Otherwise, if we don't have a retainable type, there's nothing to do.
// that the runtime does extra copies.
if (!type->isObjCRetainableType()) return nullptr;
Qualifiers qs = type.getQualifiers();
// If we have lifetime, that dominates.
if (Qualifiers::ObjCLifetime lifetime = qs.getObjCLifetime()) {
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 nullptr;
// Tell the runtime that this is ARC __weak, called by the
// byref routines.
case Qualifiers::OCL_Weak:
return ::buildByrefHelpers(CGM, byrefInfo,
ARCWeakByrefHelpers(valueAlignment));
// 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()) {
return ::buildByrefHelpers(CGM, byrefInfo,
ARCStrongBlockByrefHelpers(valueAlignment));
// Otherwise, we transfer ownership of the retain from the stack
// to the heap.
} else {
return ::buildByrefHelpers(CGM, byrefInfo,
ARCStrongByrefHelpers(valueAlignment));
}
}
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 nullptr;
}
if (type.isObjCGCWeak())
flags |= BLOCK_FIELD_IS_WEAK;
return ::buildByrefHelpers(CGM, byrefInfo,
ObjectByrefHelpers(valueAlignment, flags));
}
Address CodeGenFunction::emitBlockByrefAddress(Address baseAddr,
const VarDecl *var,
bool followForward) {
auto &info = getBlockByrefInfo(var);
return emitBlockByrefAddress(baseAddr, info, followForward, var->getName());
}
Address CodeGenFunction::emitBlockByrefAddress(Address baseAddr,
const BlockByrefInfo &info,
bool followForward,
const llvm::Twine &name) {
// Chase the forwarding address if requested.
if (followForward) {
Address forwardingAddr =
Builder.CreateStructGEP(baseAddr, 1, getPointerSize(), "forwarding");
baseAddr = Address(Builder.CreateLoad(forwardingAddr), info.ByrefAlignment);
}
return Builder.CreateStructGEP(baseAddr, info.FieldIndex,
info.FieldOffset, name);
}
/// BuildByrefInfo - 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
/// void *__byref_variable_layout;// only if needed
/// char padding[X]; // only if needed
/// T x;
/// } x
///
const BlockByrefInfo &CodeGenFunction::getBlockByrefInfo(const VarDecl *D) {
auto it = BlockByrefInfos.find(D);
if (it != BlockByrefInfos.end())
return it->second;
llvm::StructType *byrefType =
llvm::StructType::create(getLLVMContext(),
"struct.__block_byref_" + D->getNameAsString());
QualType Ty = D->getType();
CharUnits size;
SmallVector<llvm::Type *, 8> types;
// void *__isa;
types.push_back(Int8PtrTy);
size += getPointerSize();
// void *__forwarding;
types.push_back(llvm::PointerType::getUnqual(byrefType));
size += getPointerSize();
// int32_t __flags;
types.push_back(Int32Ty);
size += CharUnits::fromQuantity(4);
// int32_t __size;
types.push_back(Int32Ty);
size += CharUnits::fromQuantity(4);
// Note that this must match *exactly* the logic in buildByrefHelpers.
bool hasCopyAndDispose = getContext().BlockRequiresCopying(Ty, D);
if (hasCopyAndDispose) {
/// void *__copy_helper;
types.push_back(Int8PtrTy);
size += getPointerSize();
/// void *__destroy_helper;
types.push_back(Int8PtrTy);
size += getPointerSize();
}
bool HasByrefExtendedLayout = false;
Qualifiers::ObjCLifetime Lifetime;
if (getContext().getByrefLifetime(Ty, Lifetime, HasByrefExtendedLayout) &&
HasByrefExtendedLayout) {
/// void *__byref_variable_layout;
types.push_back(Int8PtrTy);
size += CharUnits::fromQuantity(PointerSizeInBytes);
}
// T x;
llvm::Type *varTy = ConvertTypeForMem(Ty);
bool packed = false;
CharUnits varAlign = getContext().getDeclAlign(D);
CharUnits varOffset = size.alignTo(varAlign);
// We may have to insert padding.
if (varOffset != size) {
llvm::Type *paddingTy =
llvm::ArrayType::get(Int8Ty, (varOffset - size).getQuantity());
types.push_back(paddingTy);
size = varOffset;
// Conversely, we might have to prevent LLVM from inserting padding.
} else if (CGM.getDataLayout().getABITypeAlignment(varTy)
> varAlign.getQuantity()) {
packed = true;
}
types.push_back(varTy);
byrefType->setBody(types, packed);
BlockByrefInfo info;
info.Type = byrefType;
info.FieldIndex = types.size() - 1;
info.FieldOffset = varOffset;
info.ByrefAlignment = std::max(varAlign, getPointerAlign());
auto pair = BlockByrefInfos.insert({D, info});
assert(pair.second && "info was inserted recursively?");
return pair.first->second;
}
/// 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.
Address addr = emission.Addr;
// That's an alloca of the byref structure type.
llvm::StructType *byrefType = cast<llvm::StructType>(
cast<llvm::PointerType>(addr.getPointer()->getType())->getElementType());
unsigned nextHeaderIndex = 0;
CharUnits nextHeaderOffset;
auto storeHeaderField = [&](llvm::Value *value, CharUnits fieldSize,
const Twine &name) {
auto fieldAddr = Builder.CreateStructGEP(addr, nextHeaderIndex,
nextHeaderOffset, name);
Builder.CreateStore(value, fieldAddr);
nextHeaderIndex++;
nextHeaderOffset += fieldSize;
};
// Build the byref helpers if necessary. This is null if we don't need any.
BlockByrefHelpers *helpers = buildByrefHelpers(*byrefType, 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.
int isa = 0;
if (type.isObjCGCWeak())
isa = 1;
V = Builder.CreateIntToPtr(Builder.getInt32(isa), Int8PtrTy, "isa");
storeHeaderField(V, getPointerSize(), "byref.isa");
// Store the address of the variable into its own forwarding pointer.
storeHeaderField(addr.getPointer(), getPointerSize(), "byref.forwarding");
// Blocks ABI:
// c) the flags field is set to either 0 if no helper functions are
// needed or BLOCK_BYREF_HAS_COPY_DISPOSE if they are,
BlockFlags flags;
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");
}
}
storeHeaderField(llvm::ConstantInt::get(IntTy, flags.getBitMask()),
getIntSize(), "byref.flags");
CharUnits byrefSize = CGM.GetTargetTypeStoreSize(byrefType);
V = llvm::ConstantInt::get(IntTy, byrefSize.getQuantity());
storeHeaderField(V, getIntSize(), "byref.size");
if (helpers) {
storeHeaderField(helpers->CopyHelper, getPointerSize(),
"byref.copyHelper");
storeHeaderField(helpers->DisposeHelper, getPointerSize(),
"byref.disposeHelper");
}
if (ByRefHasLifetime && HasByrefExtendedLayout) {
auto layoutInfo = CGM.getObjCRuntime().BuildByrefLayout(CGM, type);
storeHeaderField(layoutInfo, getPointerSize(), "byref.layout");
}
}
void CodeGenFunction::BuildBlockRelease(llvm::Value *V, BlockFieldFlags flags) {
llvm::Value *F = CGM.getBlockObjectDispose();
llvm::Value *args[] = {
Builder.CreateBitCast(V, Int8PtrTy),
llvm::ConstantInt::get(Int32Ty, flags.getBitMask())
};
EmitNounwindRuntimeCall(F, args); // FIXME: throwing destructors?
}
namespace {
/// Release a __block variable.
struct CallBlockRelease final : EHScopeStack::Cleanup {
llvm::Value *Addr;
CallBlockRelease(llvm::Value *Addr) : Addr(Addr) {}
void Emit(CodeGenFunction &CGF, Flags flags) override {
// Should we be passing FIELD_IS_WEAK here?
CGF.BuildBlockRelease(Addr, BLOCK_FIELD_IS_BYREF);
}
};
} // end anonymous namespace
/// 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.Addr.getPointer());
}
/// Adjust the declaration of something from the blocks API.
static void configureBlocksRuntimeObject(CodeGenModule &CGM,
llvm::Constant *C) {
auto *GV = cast<llvm::GlobalValue>(C->stripPointerCasts());
if (CGM.getTarget().getTriple().isOSBinFormatCOFF()) {
IdentifierInfo &II = CGM.getContext().Idents.get(C->getName());
TranslationUnitDecl *TUDecl = CGM.getContext().getTranslationUnitDecl();
DeclContext *DC = TranslationUnitDecl::castToDeclContext(TUDecl);
assert((isa<llvm::Function>(C->stripPointerCasts()) ||
isa<llvm::GlobalVariable>(C->stripPointerCasts())) &&
"expected Function or GlobalVariable");
const NamedDecl *ND = nullptr;
for (const auto &Result : DC->lookup(&II))
if ((ND = dyn_cast<FunctionDecl>(Result)) ||
(ND = dyn_cast<VarDecl>(Result)))
break;
// TODO: support static blocks runtime
if (GV->isDeclaration() && (!ND || !ND->hasAttr<DLLExportAttr>())) {
GV->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass);
GV->setLinkage(llvm::GlobalValue::ExternalLinkage);
} else {
GV->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);
GV->setLinkage(llvm::GlobalValue::ExternalLinkage);
}
}
if (!CGM.getLangOpts().BlocksRuntimeOptional)
return;
if (GV->isDeclaration() && GV->hasExternalLinkage())
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(),
nullptr);
configureBlocksRuntimeObject(*this, NSConcreteGlobalBlock);
return NSConcreteGlobalBlock;
}
llvm::Constant *CodeGenModule::getNSConcreteStackBlock() {
if (NSConcreteStackBlock)
return NSConcreteStackBlock;
NSConcreteStackBlock = GetOrCreateLLVMGlobal("_NSConcreteStackBlock",
Int8PtrTy->getPointerTo(),
nullptr);
configureBlocksRuntimeObject(*this, NSConcreteStackBlock);
return NSConcreteStackBlock;
}
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