1 //===--- CGBlocks.cpp - Emit LLVM Code for declarations ---------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This contains code to emit blocks.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "CGBlocks.h"
14 #include "CGCXXABI.h"
15 #include "CGDebugInfo.h"
16 #include "CGObjCRuntime.h"
17 #include "CGOpenCLRuntime.h"
18 #include "CodeGenFunction.h"
19 #include "CodeGenModule.h"
20 #include "ConstantEmitter.h"
21 #include "TargetInfo.h"
22 #include "clang/AST/Attr.h"
23 #include "clang/AST/DeclObjC.h"
24 #include "clang/CodeGen/ConstantInitBuilder.h"
25 #include "llvm/ADT/SmallSet.h"
26 #include "llvm/IR/DataLayout.h"
27 #include "llvm/IR/Module.h"
28 #include "llvm/Support/ScopedPrinter.h"
29 #include <algorithm>
30 #include <cstdio>
31
32 using namespace clang;
33 using namespace CodeGen;
34
CGBlockInfo(const BlockDecl * block,StringRef name)35 CGBlockInfo::CGBlockInfo(const BlockDecl *block, StringRef name)
36 : Name(name), CXXThisIndex(0), CanBeGlobal(false), NeedsCopyDispose(false),
37 HasCXXObject(false), UsesStret(false), HasCapturedVariableLayout(false),
38 CapturesNonExternalType(false), LocalAddress(Address::invalid()),
39 StructureType(nullptr), Block(block), DominatingIP(nullptr) {
40
41 // Skip asm prefix, if any. 'name' is usually taken directly from
42 // the mangled name of the enclosing function.
43 if (!name.empty() && name[0] == '\01')
44 name = name.substr(1);
45 }
46
47 // Anchor the vtable to this translation unit.
~BlockByrefHelpers()48 BlockByrefHelpers::~BlockByrefHelpers() {}
49
50 /// Build the given block as a global block.
51 static llvm::Constant *buildGlobalBlock(CodeGenModule &CGM,
52 const CGBlockInfo &blockInfo,
53 llvm::Constant *blockFn);
54
55 /// Build the helper function to copy a block.
buildCopyHelper(CodeGenModule & CGM,const CGBlockInfo & blockInfo)56 static llvm::Constant *buildCopyHelper(CodeGenModule &CGM,
57 const CGBlockInfo &blockInfo) {
58 return CodeGenFunction(CGM).GenerateCopyHelperFunction(blockInfo);
59 }
60
61 /// Build the helper function to dispose of a block.
buildDisposeHelper(CodeGenModule & CGM,const CGBlockInfo & blockInfo)62 static llvm::Constant *buildDisposeHelper(CodeGenModule &CGM,
63 const CGBlockInfo &blockInfo) {
64 return CodeGenFunction(CGM).GenerateDestroyHelperFunction(blockInfo);
65 }
66
67 namespace {
68
69 /// Represents a type of copy/destroy operation that should be performed for an
70 /// entity that's captured by a block.
71 enum class BlockCaptureEntityKind {
72 CXXRecord, // Copy or destroy
73 ARCWeak,
74 ARCStrong,
75 NonTrivialCStruct,
76 BlockObject, // Assign or release
77 None
78 };
79
80 /// Represents a captured entity that requires extra operations in order for
81 /// this entity to be copied or destroyed correctly.
82 struct BlockCaptureManagedEntity {
83 BlockCaptureEntityKind CopyKind, DisposeKind;
84 BlockFieldFlags CopyFlags, DisposeFlags;
85 const BlockDecl::Capture *CI;
86 const CGBlockInfo::Capture *Capture;
87
BlockCaptureManagedEntity__anon5c6b972f0111::BlockCaptureManagedEntity88 BlockCaptureManagedEntity(BlockCaptureEntityKind CopyType,
89 BlockCaptureEntityKind DisposeType,
90 BlockFieldFlags CopyFlags,
91 BlockFieldFlags DisposeFlags,
92 const BlockDecl::Capture &CI,
93 const CGBlockInfo::Capture &Capture)
94 : CopyKind(CopyType), DisposeKind(DisposeType), CopyFlags(CopyFlags),
95 DisposeFlags(DisposeFlags), CI(&CI), Capture(&Capture) {}
96
operator <__anon5c6b972f0111::BlockCaptureManagedEntity97 bool operator<(const BlockCaptureManagedEntity &Other) const {
98 return Capture->getOffset() < Other.Capture->getOffset();
99 }
100 };
101
102 enum class CaptureStrKind {
103 // String for the copy helper.
104 CopyHelper,
105 // String for the dispose helper.
106 DisposeHelper,
107 // Merge the strings for the copy helper and dispose helper.
108 Merged
109 };
110
111 } // end anonymous namespace
112
113 static void findBlockCapturedManagedEntities(
114 const CGBlockInfo &BlockInfo, const LangOptions &LangOpts,
115 SmallVectorImpl<BlockCaptureManagedEntity> &ManagedCaptures);
116
117 static std::string getBlockCaptureStr(const BlockCaptureManagedEntity &E,
118 CaptureStrKind StrKind,
119 CharUnits BlockAlignment,
120 CodeGenModule &CGM);
121
getBlockDescriptorName(const CGBlockInfo & BlockInfo,CodeGenModule & CGM)122 static std::string getBlockDescriptorName(const CGBlockInfo &BlockInfo,
123 CodeGenModule &CGM) {
124 std::string Name = "__block_descriptor_";
125 Name += llvm::to_string(BlockInfo.BlockSize.getQuantity()) + "_";
126
127 if (BlockInfo.needsCopyDisposeHelpers()) {
128 if (CGM.getLangOpts().Exceptions)
129 Name += "e";
130 if (CGM.getCodeGenOpts().ObjCAutoRefCountExceptions)
131 Name += "a";
132 Name += llvm::to_string(BlockInfo.BlockAlign.getQuantity()) + "_";
133
134 SmallVector<BlockCaptureManagedEntity, 4> ManagedCaptures;
135 findBlockCapturedManagedEntities(BlockInfo, CGM.getContext().getLangOpts(),
136 ManagedCaptures);
137
138 for (const BlockCaptureManagedEntity &E : ManagedCaptures) {
139 Name += llvm::to_string(E.Capture->getOffset().getQuantity());
140
141 if (E.CopyKind == E.DisposeKind) {
142 // If CopyKind and DisposeKind are the same, merge the capture
143 // information.
144 assert(E.CopyKind != BlockCaptureEntityKind::None &&
145 "shouldn't see BlockCaptureManagedEntity that is None");
146 Name += getBlockCaptureStr(E, CaptureStrKind::Merged,
147 BlockInfo.BlockAlign, CGM);
148 } else {
149 // If CopyKind and DisposeKind are not the same, which can happen when
150 // either Kind is None or the captured object is a __strong block,
151 // concatenate the copy and dispose strings.
152 Name += getBlockCaptureStr(E, CaptureStrKind::CopyHelper,
153 BlockInfo.BlockAlign, CGM);
154 Name += getBlockCaptureStr(E, CaptureStrKind::DisposeHelper,
155 BlockInfo.BlockAlign, CGM);
156 }
157 }
158 Name += "_";
159 }
160
161 std::string TypeAtEncoding =
162 CGM.getContext().getObjCEncodingForBlock(BlockInfo.getBlockExpr());
163 /// Replace occurrences of '@' with '\1'. '@' is reserved on ELF platforms as
164 /// a separator between symbol name and symbol version.
165 std::replace(TypeAtEncoding.begin(), TypeAtEncoding.end(), '@', '\1');
166 Name += "e" + llvm::to_string(TypeAtEncoding.size()) + "_" + TypeAtEncoding;
167 Name += "l" + CGM.getObjCRuntime().getRCBlockLayoutStr(CGM, BlockInfo);
168 return Name;
169 }
170
171 /// buildBlockDescriptor - Build the block descriptor meta-data for a block.
172 /// buildBlockDescriptor is accessed from 5th field of the Block_literal
173 /// meta-data and contains stationary information about the block literal.
174 /// Its definition will have 4 (or optionally 6) words.
175 /// \code
176 /// struct Block_descriptor {
177 /// unsigned long reserved;
178 /// unsigned long size; // size of Block_literal metadata in bytes.
179 /// void *copy_func_helper_decl; // optional copy helper.
180 /// void *destroy_func_decl; // optional destructor helper.
181 /// void *block_method_encoding_address; // @encode for block literal signature.
182 /// void *block_layout_info; // encoding of captured block variables.
183 /// };
184 /// \endcode
buildBlockDescriptor(CodeGenModule & CGM,const CGBlockInfo & blockInfo)185 static llvm::Constant *buildBlockDescriptor(CodeGenModule &CGM,
186 const CGBlockInfo &blockInfo) {
187 ASTContext &C = CGM.getContext();
188
189 llvm::IntegerType *ulong =
190 cast<llvm::IntegerType>(CGM.getTypes().ConvertType(C.UnsignedLongTy));
191 llvm::PointerType *i8p = nullptr;
192 if (CGM.getLangOpts().OpenCL)
193 i8p =
194 llvm::Type::getInt8PtrTy(
195 CGM.getLLVMContext(), C.getTargetAddressSpace(LangAS::opencl_constant));
196 else
197 i8p = CGM.VoidPtrTy;
198
199 std::string descName;
200
201 // If an equivalent block descriptor global variable exists, return it.
202 if (C.getLangOpts().ObjC &&
203 CGM.getLangOpts().getGC() == LangOptions::NonGC) {
204 descName = getBlockDescriptorName(blockInfo, CGM);
205 if (llvm::GlobalValue *desc = CGM.getModule().getNamedValue(descName))
206 return llvm::ConstantExpr::getBitCast(desc,
207 CGM.getBlockDescriptorType());
208 }
209
210 // If there isn't an equivalent block descriptor global variable, create a new
211 // one.
212 ConstantInitBuilder builder(CGM);
213 auto elements = builder.beginStruct();
214
215 // reserved
216 elements.addInt(ulong, 0);
217
218 // Size
219 // FIXME: What is the right way to say this doesn't fit? We should give
220 // a user diagnostic in that case. Better fix would be to change the
221 // API to size_t.
222 elements.addInt(ulong, blockInfo.BlockSize.getQuantity());
223
224 // Optional copy/dispose helpers.
225 bool hasInternalHelper = false;
226 if (blockInfo.needsCopyDisposeHelpers()) {
227 // copy_func_helper_decl
228 llvm::Constant *copyHelper = buildCopyHelper(CGM, blockInfo);
229 elements.add(copyHelper);
230
231 // destroy_func_decl
232 llvm::Constant *disposeHelper = buildDisposeHelper(CGM, blockInfo);
233 elements.add(disposeHelper);
234
235 if (cast<llvm::Function>(copyHelper->getOperand(0))->hasInternalLinkage() ||
236 cast<llvm::Function>(disposeHelper->getOperand(0))
237 ->hasInternalLinkage())
238 hasInternalHelper = true;
239 }
240
241 // Signature. Mandatory ObjC-style method descriptor @encode sequence.
242 std::string typeAtEncoding =
243 CGM.getContext().getObjCEncodingForBlock(blockInfo.getBlockExpr());
244 elements.add(llvm::ConstantExpr::getBitCast(
245 CGM.GetAddrOfConstantCString(typeAtEncoding).getPointer(), i8p));
246
247 // GC layout.
248 if (C.getLangOpts().ObjC) {
249 if (CGM.getLangOpts().getGC() != LangOptions::NonGC)
250 elements.add(CGM.getObjCRuntime().BuildGCBlockLayout(CGM, blockInfo));
251 else
252 elements.add(CGM.getObjCRuntime().BuildRCBlockLayout(CGM, blockInfo));
253 }
254 else
255 elements.addNullPointer(i8p);
256
257 unsigned AddrSpace = 0;
258 if (C.getLangOpts().OpenCL)
259 AddrSpace = C.getTargetAddressSpace(LangAS::opencl_constant);
260
261 llvm::GlobalValue::LinkageTypes linkage;
262 if (descName.empty()) {
263 linkage = llvm::GlobalValue::InternalLinkage;
264 descName = "__block_descriptor_tmp";
265 } else if (hasInternalHelper) {
266 // If either the copy helper or the dispose helper has internal linkage,
267 // the block descriptor must have internal linkage too.
268 linkage = llvm::GlobalValue::InternalLinkage;
269 } else {
270 linkage = llvm::GlobalValue::LinkOnceODRLinkage;
271 }
272
273 llvm::GlobalVariable *global =
274 elements.finishAndCreateGlobal(descName, CGM.getPointerAlign(),
275 /*constant*/ true, linkage, AddrSpace);
276
277 if (linkage == llvm::GlobalValue::LinkOnceODRLinkage) {
278 if (CGM.supportsCOMDAT())
279 global->setComdat(CGM.getModule().getOrInsertComdat(descName));
280 global->setVisibility(llvm::GlobalValue::HiddenVisibility);
281 global->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
282 }
283
284 return llvm::ConstantExpr::getBitCast(global, CGM.getBlockDescriptorType());
285 }
286
287 /*
288 Purely notional variadic template describing the layout of a block.
289
290 template <class _ResultType, class... _ParamTypes, class... _CaptureTypes>
291 struct Block_literal {
292 /// Initialized to one of:
293 /// extern void *_NSConcreteStackBlock[];
294 /// extern void *_NSConcreteGlobalBlock[];
295 ///
296 /// In theory, we could start one off malloc'ed by setting
297 /// BLOCK_NEEDS_FREE, giving it a refcount of 1, and using
298 /// this isa:
299 /// extern void *_NSConcreteMallocBlock[];
300 struct objc_class *isa;
301
302 /// These are the flags (with corresponding bit number) that the
303 /// compiler is actually supposed to know about.
304 /// 23. BLOCK_IS_NOESCAPE - indicates that the block is non-escaping
305 /// 25. BLOCK_HAS_COPY_DISPOSE - indicates that the block
306 /// descriptor provides copy and dispose helper functions
307 /// 26. BLOCK_HAS_CXX_OBJ - indicates that there's a captured
308 /// object with a nontrivial destructor or copy constructor
309 /// 28. BLOCK_IS_GLOBAL - indicates that the block is allocated
310 /// as global memory
311 /// 29. BLOCK_USE_STRET - indicates that the block function
312 /// uses stret, which objc_msgSend needs to know about
313 /// 30. BLOCK_HAS_SIGNATURE - indicates that the block has an
314 /// @encoded signature string
315 /// And we're not supposed to manipulate these:
316 /// 24. BLOCK_NEEDS_FREE - indicates that the block has been moved
317 /// to malloc'ed memory
318 /// 27. BLOCK_IS_GC - indicates that the block has been moved to
319 /// to GC-allocated memory
320 /// Additionally, the bottom 16 bits are a reference count which
321 /// should be zero on the stack.
322 int flags;
323
324 /// Reserved; should be zero-initialized.
325 int reserved;
326
327 /// Function pointer generated from block literal.
328 _ResultType (*invoke)(Block_literal *, _ParamTypes...);
329
330 /// Block description metadata generated from block literal.
331 struct Block_descriptor *block_descriptor;
332
333 /// Captured values follow.
334 _CapturesTypes captures...;
335 };
336 */
337
338 namespace {
339 /// A chunk of data that we actually have to capture in the block.
340 struct BlockLayoutChunk {
341 CharUnits Alignment;
342 CharUnits Size;
343 Qualifiers::ObjCLifetime Lifetime;
344 const BlockDecl::Capture *Capture; // null for 'this'
345 llvm::Type *Type;
346 QualType FieldType;
347
BlockLayoutChunk__anon5c6b972f0211::BlockLayoutChunk348 BlockLayoutChunk(CharUnits align, CharUnits size,
349 Qualifiers::ObjCLifetime lifetime,
350 const BlockDecl::Capture *capture,
351 llvm::Type *type, QualType fieldType)
352 : Alignment(align), Size(size), Lifetime(lifetime),
353 Capture(capture), Type(type), FieldType(fieldType) {}
354
355 /// Tell the block info that this chunk has the given field index.
setIndex__anon5c6b972f0211::BlockLayoutChunk356 void setIndex(CGBlockInfo &info, unsigned index, CharUnits offset) {
357 if (!Capture) {
358 info.CXXThisIndex = index;
359 info.CXXThisOffset = offset;
360 } else {
361 auto C = CGBlockInfo::Capture::makeIndex(index, offset, FieldType);
362 info.Captures.insert({Capture->getVariable(), C});
363 }
364 }
365 };
366
367 /// Order by 1) all __strong together 2) next, all byfref together 3) next,
368 /// all __weak together. Preserve descending alignment in all situations.
operator <(const BlockLayoutChunk & left,const BlockLayoutChunk & right)369 bool operator<(const BlockLayoutChunk &left, const BlockLayoutChunk &right) {
370 if (left.Alignment != right.Alignment)
371 return left.Alignment > right.Alignment;
372
373 auto getPrefOrder = [](const BlockLayoutChunk &chunk) {
374 if (chunk.Capture && chunk.Capture->isByRef())
375 return 1;
376 if (chunk.Lifetime == Qualifiers::OCL_Strong)
377 return 0;
378 if (chunk.Lifetime == Qualifiers::OCL_Weak)
379 return 2;
380 return 3;
381 };
382
383 return getPrefOrder(left) < getPrefOrder(right);
384 }
385 } // end anonymous namespace
386
387 /// Determines if the given type is safe for constant capture in C++.
isSafeForCXXConstantCapture(QualType type)388 static bool isSafeForCXXConstantCapture(QualType type) {
389 const RecordType *recordType =
390 type->getBaseElementTypeUnsafe()->getAs<RecordType>();
391
392 // Only records can be unsafe.
393 if (!recordType) return true;
394
395 const auto *record = cast<CXXRecordDecl>(recordType->getDecl());
396
397 // Maintain semantics for classes with non-trivial dtors or copy ctors.
398 if (!record->hasTrivialDestructor()) return false;
399 if (record->hasNonTrivialCopyConstructor()) return false;
400
401 // Otherwise, we just have to make sure there aren't any mutable
402 // fields that might have changed since initialization.
403 return !record->hasMutableFields();
404 }
405
406 /// It is illegal to modify a const object after initialization.
407 /// Therefore, if a const object has a constant initializer, we don't
408 /// actually need to keep storage for it in the block; we'll just
409 /// rematerialize it at the start of the block function. This is
410 /// acceptable because we make no promises about address stability of
411 /// captured variables.
tryCaptureAsConstant(CodeGenModule & CGM,CodeGenFunction * CGF,const VarDecl * var)412 static llvm::Constant *tryCaptureAsConstant(CodeGenModule &CGM,
413 CodeGenFunction *CGF,
414 const VarDecl *var) {
415 // Return if this is a function parameter. We shouldn't try to
416 // rematerialize default arguments of function parameters.
417 if (isa<ParmVarDecl>(var))
418 return nullptr;
419
420 QualType type = var->getType();
421
422 // We can only do this if the variable is const.
423 if (!type.isConstQualified()) return nullptr;
424
425 // Furthermore, in C++ we have to worry about mutable fields:
426 // C++ [dcl.type.cv]p4:
427 // Except that any class member declared mutable can be
428 // modified, any attempt to modify a const object during its
429 // lifetime results in undefined behavior.
430 if (CGM.getLangOpts().CPlusPlus && !isSafeForCXXConstantCapture(type))
431 return nullptr;
432
433 // If the variable doesn't have any initializer (shouldn't this be
434 // invalid?), it's not clear what we should do. Maybe capture as
435 // zero?
436 const Expr *init = var->getInit();
437 if (!init) return nullptr;
438
439 return ConstantEmitter(CGM, CGF).tryEmitAbstractForInitializer(*var);
440 }
441
442 /// Get the low bit of a nonzero character count. This is the
443 /// alignment of the nth byte if the 0th byte is universally aligned.
getLowBit(CharUnits v)444 static CharUnits getLowBit(CharUnits v) {
445 return CharUnits::fromQuantity(v.getQuantity() & (~v.getQuantity() + 1));
446 }
447
initializeForBlockHeader(CodeGenModule & CGM,CGBlockInfo & info,SmallVectorImpl<llvm::Type * > & elementTypes)448 static void initializeForBlockHeader(CodeGenModule &CGM, CGBlockInfo &info,
449 SmallVectorImpl<llvm::Type*> &elementTypes) {
450
451 assert(elementTypes.empty());
452 if (CGM.getLangOpts().OpenCL) {
453 // The header is basically 'struct { int; int; generic void *;
454 // custom_fields; }'. Assert that struct is packed.
455 auto GenericAS =
456 CGM.getContext().getTargetAddressSpace(LangAS::opencl_generic);
457 auto GenPtrAlign =
458 CharUnits::fromQuantity(CGM.getTarget().getPointerAlign(GenericAS) / 8);
459 auto GenPtrSize =
460 CharUnits::fromQuantity(CGM.getTarget().getPointerWidth(GenericAS) / 8);
461 assert(CGM.getIntSize() <= GenPtrSize);
462 assert(CGM.getIntAlign() <= GenPtrAlign);
463 assert((2 * CGM.getIntSize()).isMultipleOf(GenPtrAlign));
464 elementTypes.push_back(CGM.IntTy); /* total size */
465 elementTypes.push_back(CGM.IntTy); /* align */
466 elementTypes.push_back(
467 CGM.getOpenCLRuntime()
468 .getGenericVoidPointerType()); /* invoke function */
469 unsigned Offset =
470 2 * CGM.getIntSize().getQuantity() + GenPtrSize.getQuantity();
471 unsigned BlockAlign = GenPtrAlign.getQuantity();
472 if (auto *Helper =
473 CGM.getTargetCodeGenInfo().getTargetOpenCLBlockHelper()) {
474 for (auto I : Helper->getCustomFieldTypes()) /* custom fields */ {
475 // TargetOpenCLBlockHelp needs to make sure the struct is packed.
476 // If necessary, add padding fields to the custom fields.
477 unsigned Align = CGM.getDataLayout().getABITypeAlignment(I);
478 if (BlockAlign < Align)
479 BlockAlign = Align;
480 assert(Offset % Align == 0);
481 Offset += CGM.getDataLayout().getTypeAllocSize(I);
482 elementTypes.push_back(I);
483 }
484 }
485 info.BlockAlign = CharUnits::fromQuantity(BlockAlign);
486 info.BlockSize = CharUnits::fromQuantity(Offset);
487 } else {
488 // The header is basically 'struct { void *; int; int; void *; void *; }'.
489 // Assert that the struct is packed.
490 assert(CGM.getIntSize() <= CGM.getPointerSize());
491 assert(CGM.getIntAlign() <= CGM.getPointerAlign());
492 assert((2 * CGM.getIntSize()).isMultipleOf(CGM.getPointerAlign()));
493 info.BlockAlign = CGM.getPointerAlign();
494 info.BlockSize = 3 * CGM.getPointerSize() + 2 * CGM.getIntSize();
495 elementTypes.push_back(CGM.VoidPtrTy);
496 elementTypes.push_back(CGM.IntTy);
497 elementTypes.push_back(CGM.IntTy);
498 elementTypes.push_back(CGM.VoidPtrTy);
499 elementTypes.push_back(CGM.getBlockDescriptorType());
500 }
501 }
502
getCaptureFieldType(const CodeGenFunction & CGF,const BlockDecl::Capture & CI)503 static QualType getCaptureFieldType(const CodeGenFunction &CGF,
504 const BlockDecl::Capture &CI) {
505 const VarDecl *VD = CI.getVariable();
506
507 // If the variable is captured by an enclosing block or lambda expression,
508 // use the type of the capture field.
509 if (CGF.BlockInfo && CI.isNested())
510 return CGF.BlockInfo->getCapture(VD).fieldType();
511 if (auto *FD = CGF.LambdaCaptureFields.lookup(VD))
512 return FD->getType();
513 // If the captured variable is a non-escaping __block variable, the field
514 // type is the reference type. If the variable is a __block variable that
515 // already has a reference type, the field type is the variable's type.
516 return VD->isNonEscapingByref() ?
517 CGF.getContext().getLValueReferenceType(VD->getType()) : VD->getType();
518 }
519
520 /// Compute the layout of the given block. Attempts to lay the block
521 /// out with minimal space requirements.
computeBlockInfo(CodeGenModule & CGM,CodeGenFunction * CGF,CGBlockInfo & info)522 static void computeBlockInfo(CodeGenModule &CGM, CodeGenFunction *CGF,
523 CGBlockInfo &info) {
524 ASTContext &C = CGM.getContext();
525 const BlockDecl *block = info.getBlockDecl();
526
527 SmallVector<llvm::Type*, 8> elementTypes;
528 initializeForBlockHeader(CGM, info, elementTypes);
529 bool hasNonConstantCustomFields = false;
530 if (auto *OpenCLHelper =
531 CGM.getTargetCodeGenInfo().getTargetOpenCLBlockHelper())
532 hasNonConstantCustomFields =
533 !OpenCLHelper->areAllCustomFieldValuesConstant(info);
534 if (!block->hasCaptures() && !hasNonConstantCustomFields) {
535 info.StructureType =
536 llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true);
537 info.CanBeGlobal = true;
538 return;
539 }
540 else if (C.getLangOpts().ObjC &&
541 CGM.getLangOpts().getGC() == LangOptions::NonGC)
542 info.HasCapturedVariableLayout = true;
543
544 // Collect the layout chunks.
545 SmallVector<BlockLayoutChunk, 16> layout;
546 layout.reserve(block->capturesCXXThis() +
547 (block->capture_end() - block->capture_begin()));
548
549 CharUnits maxFieldAlign;
550
551 // First, 'this'.
552 if (block->capturesCXXThis()) {
553 assert(CGF && CGF->CurFuncDecl && isa<CXXMethodDecl>(CGF->CurFuncDecl) &&
554 "Can't capture 'this' outside a method");
555 QualType thisType = cast<CXXMethodDecl>(CGF->CurFuncDecl)->getThisType();
556
557 // Theoretically, this could be in a different address space, so
558 // don't assume standard pointer size/align.
559 llvm::Type *llvmType = CGM.getTypes().ConvertType(thisType);
560 std::pair<CharUnits,CharUnits> tinfo
561 = CGM.getContext().getTypeInfoInChars(thisType);
562 maxFieldAlign = std::max(maxFieldAlign, tinfo.second);
563
564 layout.push_back(BlockLayoutChunk(tinfo.second, tinfo.first,
565 Qualifiers::OCL_None,
566 nullptr, llvmType, thisType));
567 }
568
569 // Next, all the block captures.
570 for (const auto &CI : block->captures()) {
571 const VarDecl *variable = CI.getVariable();
572
573 if (CI.isEscapingByref()) {
574 // We have to copy/dispose of the __block reference.
575 info.NeedsCopyDispose = true;
576
577 // Just use void* instead of a pointer to the byref type.
578 CharUnits align = CGM.getPointerAlign();
579 maxFieldAlign = std::max(maxFieldAlign, align);
580
581 // Since a __block variable cannot be captured by lambdas, its type and
582 // the capture field type should always match.
583 assert(getCaptureFieldType(*CGF, CI) == variable->getType() &&
584 "capture type differs from the variable type");
585 layout.push_back(BlockLayoutChunk(align, CGM.getPointerSize(),
586 Qualifiers::OCL_None, &CI,
587 CGM.VoidPtrTy, variable->getType()));
588 continue;
589 }
590
591 // Otherwise, build a layout chunk with the size and alignment of
592 // the declaration.
593 if (llvm::Constant *constant = tryCaptureAsConstant(CGM, CGF, variable)) {
594 info.Captures[variable] = CGBlockInfo::Capture::makeConstant(constant);
595 continue;
596 }
597
598 QualType VT = getCaptureFieldType(*CGF, CI);
599
600 // If we have a lifetime qualifier, honor it for capture purposes.
601 // That includes *not* copying it if it's __unsafe_unretained.
602 Qualifiers::ObjCLifetime lifetime = VT.getObjCLifetime();
603 if (lifetime) {
604 switch (lifetime) {
605 case Qualifiers::OCL_None: llvm_unreachable("impossible");
606 case Qualifiers::OCL_ExplicitNone:
607 case Qualifiers::OCL_Autoreleasing:
608 break;
609
610 case Qualifiers::OCL_Strong:
611 case Qualifiers::OCL_Weak:
612 info.NeedsCopyDispose = true;
613 }
614
615 // Block pointers require copy/dispose. So do Objective-C pointers.
616 } else if (VT->isObjCRetainableType()) {
617 // But honor the inert __unsafe_unretained qualifier, which doesn't
618 // actually make it into the type system.
619 if (VT->isObjCInertUnsafeUnretainedType()) {
620 lifetime = Qualifiers::OCL_ExplicitNone;
621 } else {
622 info.NeedsCopyDispose = true;
623 // used for mrr below.
624 lifetime = Qualifiers::OCL_Strong;
625 }
626
627 // So do types that require non-trivial copy construction.
628 } else if (CI.hasCopyExpr()) {
629 info.NeedsCopyDispose = true;
630 info.HasCXXObject = true;
631 if (!VT->getAsCXXRecordDecl()->isExternallyVisible())
632 info.CapturesNonExternalType = true;
633
634 // So do C structs that require non-trivial copy construction or
635 // destruction.
636 } else if (VT.isNonTrivialToPrimitiveCopy() == QualType::PCK_Struct ||
637 VT.isDestructedType() == QualType::DK_nontrivial_c_struct) {
638 info.NeedsCopyDispose = true;
639
640 // And so do types with destructors.
641 } else if (CGM.getLangOpts().CPlusPlus) {
642 if (const CXXRecordDecl *record = VT->getAsCXXRecordDecl()) {
643 if (!record->hasTrivialDestructor()) {
644 info.HasCXXObject = true;
645 info.NeedsCopyDispose = true;
646 if (!record->isExternallyVisible())
647 info.CapturesNonExternalType = true;
648 }
649 }
650 }
651
652 CharUnits size = C.getTypeSizeInChars(VT);
653 CharUnits align = C.getDeclAlign(variable);
654
655 maxFieldAlign = std::max(maxFieldAlign, align);
656
657 llvm::Type *llvmType =
658 CGM.getTypes().ConvertTypeForMem(VT);
659
660 layout.push_back(
661 BlockLayoutChunk(align, size, lifetime, &CI, llvmType, VT));
662 }
663
664 // If that was everything, we're done here.
665 if (layout.empty()) {
666 info.StructureType =
667 llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true);
668 info.CanBeGlobal = true;
669 return;
670 }
671
672 // Sort the layout by alignment. We have to use a stable sort here
673 // to get reproducible results. There should probably be an
674 // llvm::array_pod_stable_sort.
675 llvm::stable_sort(layout);
676
677 // Needed for blocks layout info.
678 info.BlockHeaderForcedGapOffset = info.BlockSize;
679 info.BlockHeaderForcedGapSize = CharUnits::Zero();
680
681 CharUnits &blockSize = info.BlockSize;
682 info.BlockAlign = std::max(maxFieldAlign, info.BlockAlign);
683
684 // Assuming that the first byte in the header is maximally aligned,
685 // get the alignment of the first byte following the header.
686 CharUnits endAlign = getLowBit(blockSize);
687
688 // If the end of the header isn't satisfactorily aligned for the
689 // maximum thing, look for things that are okay with the header-end
690 // alignment, and keep appending them until we get something that's
691 // aligned right. This algorithm is only guaranteed optimal if
692 // that condition is satisfied at some point; otherwise we can get
693 // things like:
694 // header // next byte has alignment 4
695 // something_with_size_5; // next byte has alignment 1
696 // something_with_alignment_8;
697 // which has 7 bytes of padding, as opposed to the naive solution
698 // which might have less (?).
699 if (endAlign < maxFieldAlign) {
700 SmallVectorImpl<BlockLayoutChunk>::iterator
701 li = layout.begin() + 1, le = layout.end();
702
703 // Look for something that the header end is already
704 // satisfactorily aligned for.
705 for (; li != le && endAlign < li->Alignment; ++li)
706 ;
707
708 // If we found something that's naturally aligned for the end of
709 // the header, keep adding things...
710 if (li != le) {
711 SmallVectorImpl<BlockLayoutChunk>::iterator first = li;
712 for (; li != le; ++li) {
713 assert(endAlign >= li->Alignment);
714
715 li->setIndex(info, elementTypes.size(), blockSize);
716 elementTypes.push_back(li->Type);
717 blockSize += li->Size;
718 endAlign = getLowBit(blockSize);
719
720 // ...until we get to the alignment of the maximum field.
721 if (endAlign >= maxFieldAlign) {
722 break;
723 }
724 }
725 // Don't re-append everything we just appended.
726 layout.erase(first, li);
727 }
728 }
729
730 assert(endAlign == getLowBit(blockSize));
731
732 // At this point, we just have to add padding if the end align still
733 // isn't aligned right.
734 if (endAlign < maxFieldAlign) {
735 CharUnits newBlockSize = blockSize.alignTo(maxFieldAlign);
736 CharUnits padding = newBlockSize - blockSize;
737
738 // If we haven't yet added any fields, remember that there was an
739 // initial gap; this need to go into the block layout bit map.
740 if (blockSize == info.BlockHeaderForcedGapOffset) {
741 info.BlockHeaderForcedGapSize = padding;
742 }
743
744 elementTypes.push_back(llvm::ArrayType::get(CGM.Int8Ty,
745 padding.getQuantity()));
746 blockSize = newBlockSize;
747 endAlign = getLowBit(blockSize); // might be > maxFieldAlign
748 }
749
750 assert(endAlign >= maxFieldAlign);
751 assert(endAlign == getLowBit(blockSize));
752 // Slam everything else on now. This works because they have
753 // strictly decreasing alignment and we expect that size is always a
754 // multiple of alignment.
755 for (SmallVectorImpl<BlockLayoutChunk>::iterator
756 li = layout.begin(), le = layout.end(); li != le; ++li) {
757 if (endAlign < li->Alignment) {
758 // size may not be multiple of alignment. This can only happen with
759 // an over-aligned variable. We will be adding a padding field to
760 // make the size be multiple of alignment.
761 CharUnits padding = li->Alignment - endAlign;
762 elementTypes.push_back(llvm::ArrayType::get(CGM.Int8Ty,
763 padding.getQuantity()));
764 blockSize += padding;
765 endAlign = getLowBit(blockSize);
766 }
767 assert(endAlign >= li->Alignment);
768 li->setIndex(info, elementTypes.size(), blockSize);
769 elementTypes.push_back(li->Type);
770 blockSize += li->Size;
771 endAlign = getLowBit(blockSize);
772 }
773
774 info.StructureType =
775 llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true);
776 }
777
778 /// Enter the scope of a block. This should be run at the entrance to
779 /// a full-expression so that the block's cleanups are pushed at the
780 /// right place in the stack.
enterBlockScope(CodeGenFunction & CGF,BlockDecl * block)781 static void enterBlockScope(CodeGenFunction &CGF, BlockDecl *block) {
782 assert(CGF.HaveInsertPoint());
783
784 // Allocate the block info and place it at the head of the list.
785 CGBlockInfo &blockInfo =
786 *new CGBlockInfo(block, CGF.CurFn->getName());
787 blockInfo.NextBlockInfo = CGF.FirstBlockInfo;
788 CGF.FirstBlockInfo = &blockInfo;
789
790 // Compute information about the layout, etc., of this block,
791 // pushing cleanups as necessary.
792 computeBlockInfo(CGF.CGM, &CGF, blockInfo);
793
794 // Nothing else to do if it can be global.
795 if (blockInfo.CanBeGlobal) return;
796
797 // Make the allocation for the block.
798 blockInfo.LocalAddress = CGF.CreateTempAlloca(blockInfo.StructureType,
799 blockInfo.BlockAlign, "block");
800
801 // If there are cleanups to emit, enter them (but inactive).
802 if (!blockInfo.NeedsCopyDispose) return;
803
804 // Walk through the captures (in order) and find the ones not
805 // captured by constant.
806 for (const auto &CI : block->captures()) {
807 // Ignore __block captures; there's nothing special in the
808 // on-stack block that we need to do for them.
809 if (CI.isByRef()) continue;
810
811 // Ignore variables that are constant-captured.
812 const VarDecl *variable = CI.getVariable();
813 CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
814 if (capture.isConstant()) continue;
815
816 // Ignore objects that aren't destructed.
817 QualType VT = getCaptureFieldType(CGF, CI);
818 QualType::DestructionKind dtorKind = VT.isDestructedType();
819 if (dtorKind == QualType::DK_none) continue;
820
821 CodeGenFunction::Destroyer *destroyer;
822
823 // Block captures count as local values and have imprecise semantics.
824 // They also can't be arrays, so need to worry about that.
825 //
826 // For const-qualified captures, emit clang.arc.use to ensure the captured
827 // object doesn't get released while we are still depending on its validity
828 // within the block.
829 if (VT.isConstQualified() &&
830 VT.getObjCLifetime() == Qualifiers::OCL_Strong &&
831 CGF.CGM.getCodeGenOpts().OptimizationLevel != 0) {
832 assert(CGF.CGM.getLangOpts().ObjCAutoRefCount &&
833 "expected ObjC ARC to be enabled");
834 destroyer = CodeGenFunction::emitARCIntrinsicUse;
835 } else if (dtorKind == QualType::DK_objc_strong_lifetime) {
836 destroyer = CodeGenFunction::destroyARCStrongImprecise;
837 } else {
838 destroyer = CGF.getDestroyer(dtorKind);
839 }
840
841 // GEP down to the address.
842 Address addr =
843 CGF.Builder.CreateStructGEP(blockInfo.LocalAddress, capture.getIndex());
844
845 // We can use that GEP as the dominating IP.
846 if (!blockInfo.DominatingIP)
847 blockInfo.DominatingIP = cast<llvm::Instruction>(addr.getPointer());
848
849 CleanupKind cleanupKind = InactiveNormalCleanup;
850 bool useArrayEHCleanup = CGF.needsEHCleanup(dtorKind);
851 if (useArrayEHCleanup)
852 cleanupKind = InactiveNormalAndEHCleanup;
853
854 CGF.pushDestroy(cleanupKind, addr, VT,
855 destroyer, useArrayEHCleanup);
856
857 // Remember where that cleanup was.
858 capture.setCleanup(CGF.EHStack.stable_begin());
859 }
860 }
861
862 /// Enter a full-expression with a non-trivial number of objects to
863 /// clean up. This is in this file because, at the moment, the only
864 /// kind of cleanup object is a BlockDecl*.
enterNonTrivialFullExpression(const FullExpr * E)865 void CodeGenFunction::enterNonTrivialFullExpression(const FullExpr *E) {
866 if (const auto EWC = dyn_cast<ExprWithCleanups>(E)) {
867 assert(EWC->getNumObjects() != 0);
868 for (const ExprWithCleanups::CleanupObject &C : EWC->getObjects())
869 enterBlockScope(*this, C);
870 }
871 }
872
873 /// Find the layout for the given block in a linked list and remove it.
findAndRemoveBlockInfo(CGBlockInfo ** head,const BlockDecl * block)874 static CGBlockInfo *findAndRemoveBlockInfo(CGBlockInfo **head,
875 const BlockDecl *block) {
876 while (true) {
877 assert(head && *head);
878 CGBlockInfo *cur = *head;
879
880 // If this is the block we're looking for, splice it out of the list.
881 if (cur->getBlockDecl() == block) {
882 *head = cur->NextBlockInfo;
883 return cur;
884 }
885
886 head = &cur->NextBlockInfo;
887 }
888 }
889
890 /// Destroy a chain of block layouts.
destroyBlockInfos(CGBlockInfo * head)891 void CodeGenFunction::destroyBlockInfos(CGBlockInfo *head) {
892 assert(head && "destroying an empty chain");
893 do {
894 CGBlockInfo *cur = head;
895 head = cur->NextBlockInfo;
896 delete cur;
897 } while (head != nullptr);
898 }
899
900 /// Emit a block literal expression in the current function.
EmitBlockLiteral(const BlockExpr * blockExpr)901 llvm::Value *CodeGenFunction::EmitBlockLiteral(const BlockExpr *blockExpr) {
902 // If the block has no captures, we won't have a pre-computed
903 // layout for it.
904 if (!blockExpr->getBlockDecl()->hasCaptures()) {
905 // The block literal is emitted as a global variable, and the block invoke
906 // function has to be extracted from its initializer.
907 if (llvm::Constant *Block = CGM.getAddrOfGlobalBlockIfEmitted(blockExpr)) {
908 return Block;
909 }
910 CGBlockInfo blockInfo(blockExpr->getBlockDecl(), CurFn->getName());
911 computeBlockInfo(CGM, this, blockInfo);
912 blockInfo.BlockExpression = blockExpr;
913 return EmitBlockLiteral(blockInfo);
914 }
915
916 // Find the block info for this block and take ownership of it.
917 std::unique_ptr<CGBlockInfo> blockInfo;
918 blockInfo.reset(findAndRemoveBlockInfo(&FirstBlockInfo,
919 blockExpr->getBlockDecl()));
920
921 blockInfo->BlockExpression = blockExpr;
922 return EmitBlockLiteral(*blockInfo);
923 }
924
EmitBlockLiteral(const CGBlockInfo & blockInfo)925 llvm::Value *CodeGenFunction::EmitBlockLiteral(const CGBlockInfo &blockInfo) {
926 bool IsOpenCL = CGM.getContext().getLangOpts().OpenCL;
927 auto GenVoidPtrTy =
928 IsOpenCL ? CGM.getOpenCLRuntime().getGenericVoidPointerType() : VoidPtrTy;
929 LangAS GenVoidPtrAddr = IsOpenCL ? LangAS::opencl_generic : LangAS::Default;
930 auto GenVoidPtrSize = CharUnits::fromQuantity(
931 CGM.getTarget().getPointerWidth(
932 CGM.getContext().getTargetAddressSpace(GenVoidPtrAddr)) /
933 8);
934 // Using the computed layout, generate the actual block function.
935 bool isLambdaConv = blockInfo.getBlockDecl()->isConversionFromLambda();
936 CodeGenFunction BlockCGF{CGM, true};
937 BlockCGF.SanOpts = SanOpts;
938 auto *InvokeFn = BlockCGF.GenerateBlockFunction(
939 CurGD, blockInfo, LocalDeclMap, isLambdaConv, blockInfo.CanBeGlobal);
940 auto *blockFn = llvm::ConstantExpr::getPointerCast(InvokeFn, GenVoidPtrTy);
941
942 // If there is nothing to capture, we can emit this as a global block.
943 if (blockInfo.CanBeGlobal)
944 return CGM.getAddrOfGlobalBlockIfEmitted(blockInfo.BlockExpression);
945
946 // Otherwise, we have to emit this as a local block.
947
948 Address blockAddr = blockInfo.LocalAddress;
949 assert(blockAddr.isValid() && "block has no address!");
950
951 llvm::Constant *isa;
952 llvm::Constant *descriptor;
953 BlockFlags flags;
954 if (!IsOpenCL) {
955 // If the block is non-escaping, set field 'isa 'to NSConcreteGlobalBlock
956 // and set the BLOCK_IS_GLOBAL bit of field 'flags'. Copying a non-escaping
957 // block just returns the original block and releasing it is a no-op.
958 llvm::Constant *blockISA = blockInfo.getBlockDecl()->doesNotEscape()
959 ? CGM.getNSConcreteGlobalBlock()
960 : CGM.getNSConcreteStackBlock();
961 isa = llvm::ConstantExpr::getBitCast(blockISA, VoidPtrTy);
962
963 // Build the block descriptor.
964 descriptor = buildBlockDescriptor(CGM, blockInfo);
965
966 // Compute the initial on-stack block flags.
967 flags = BLOCK_HAS_SIGNATURE;
968 if (blockInfo.HasCapturedVariableLayout)
969 flags |= BLOCK_HAS_EXTENDED_LAYOUT;
970 if (blockInfo.needsCopyDisposeHelpers())
971 flags |= BLOCK_HAS_COPY_DISPOSE;
972 if (blockInfo.HasCXXObject)
973 flags |= BLOCK_HAS_CXX_OBJ;
974 if (blockInfo.UsesStret)
975 flags |= BLOCK_USE_STRET;
976 if (blockInfo.getBlockDecl()->doesNotEscape())
977 flags |= BLOCK_IS_NOESCAPE | BLOCK_IS_GLOBAL;
978 }
979
980 auto projectField = [&](unsigned index, const Twine &name) -> Address {
981 return Builder.CreateStructGEP(blockAddr, index, name);
982 };
983 auto storeField = [&](llvm::Value *value, unsigned index, const Twine &name) {
984 Builder.CreateStore(value, projectField(index, name));
985 };
986
987 // Initialize the block header.
988 {
989 // We assume all the header fields are densely packed.
990 unsigned index = 0;
991 CharUnits offset;
992 auto addHeaderField = [&](llvm::Value *value, CharUnits size,
993 const Twine &name) {
994 storeField(value, index, name);
995 offset += size;
996 index++;
997 };
998
999 if (!IsOpenCL) {
1000 addHeaderField(isa, getPointerSize(), "block.isa");
1001 addHeaderField(llvm::ConstantInt::get(IntTy, flags.getBitMask()),
1002 getIntSize(), "block.flags");
1003 addHeaderField(llvm::ConstantInt::get(IntTy, 0), getIntSize(),
1004 "block.reserved");
1005 } else {
1006 addHeaderField(
1007 llvm::ConstantInt::get(IntTy, blockInfo.BlockSize.getQuantity()),
1008 getIntSize(), "block.size");
1009 addHeaderField(
1010 llvm::ConstantInt::get(IntTy, blockInfo.BlockAlign.getQuantity()),
1011 getIntSize(), "block.align");
1012 }
1013 addHeaderField(blockFn, GenVoidPtrSize, "block.invoke");
1014 if (!IsOpenCL)
1015 addHeaderField(descriptor, getPointerSize(), "block.descriptor");
1016 else if (auto *Helper =
1017 CGM.getTargetCodeGenInfo().getTargetOpenCLBlockHelper()) {
1018 for (auto I : Helper->getCustomFieldValues(*this, blockInfo)) {
1019 addHeaderField(
1020 I.first,
1021 CharUnits::fromQuantity(
1022 CGM.getDataLayout().getTypeAllocSize(I.first->getType())),
1023 I.second);
1024 }
1025 }
1026 }
1027
1028 // Finally, capture all the values into the block.
1029 const BlockDecl *blockDecl = blockInfo.getBlockDecl();
1030
1031 // First, 'this'.
1032 if (blockDecl->capturesCXXThis()) {
1033 Address addr =
1034 projectField(blockInfo.CXXThisIndex, "block.captured-this.addr");
1035 Builder.CreateStore(LoadCXXThis(), addr);
1036 }
1037
1038 // Next, captured variables.
1039 for (const auto &CI : blockDecl->captures()) {
1040 const VarDecl *variable = CI.getVariable();
1041 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
1042
1043 // Ignore constant captures.
1044 if (capture.isConstant()) continue;
1045
1046 QualType type = capture.fieldType();
1047
1048 // This will be a [[type]]*, except that a byref entry will just be
1049 // an i8**.
1050 Address blockField = projectField(capture.getIndex(), "block.captured");
1051
1052 // Compute the address of the thing we're going to move into the
1053 // block literal.
1054 Address src = Address::invalid();
1055
1056 if (blockDecl->isConversionFromLambda()) {
1057 // The lambda capture in a lambda's conversion-to-block-pointer is
1058 // special; we'll simply emit it directly.
1059 src = Address::invalid();
1060 } else if (CI.isEscapingByref()) {
1061 if (BlockInfo && CI.isNested()) {
1062 // We need to use the capture from the enclosing block.
1063 const CGBlockInfo::Capture &enclosingCapture =
1064 BlockInfo->getCapture(variable);
1065
1066 // This is a [[type]]*, except that a byref entry will just be an i8**.
1067 src = Builder.CreateStructGEP(LoadBlockStruct(),
1068 enclosingCapture.getIndex(),
1069 "block.capture.addr");
1070 } else {
1071 auto I = LocalDeclMap.find(variable);
1072 assert(I != LocalDeclMap.end());
1073 src = I->second;
1074 }
1075 } else {
1076 DeclRefExpr declRef(getContext(), const_cast<VarDecl *>(variable),
1077 /*RefersToEnclosingVariableOrCapture*/ CI.isNested(),
1078 type.getNonReferenceType(), VK_LValue,
1079 SourceLocation());
1080 src = EmitDeclRefLValue(&declRef).getAddress(*this);
1081 };
1082
1083 // For byrefs, we just write the pointer to the byref struct into
1084 // the block field. There's no need to chase the forwarding
1085 // pointer at this point, since we're building something that will
1086 // live a shorter life than the stack byref anyway.
1087 if (CI.isEscapingByref()) {
1088 // Get a void* that points to the byref struct.
1089 llvm::Value *byrefPointer;
1090 if (CI.isNested())
1091 byrefPointer = Builder.CreateLoad(src, "byref.capture");
1092 else
1093 byrefPointer = Builder.CreateBitCast(src.getPointer(), VoidPtrTy);
1094
1095 // Write that void* into the capture field.
1096 Builder.CreateStore(byrefPointer, blockField);
1097
1098 // If we have a copy constructor, evaluate that into the block field.
1099 } else if (const Expr *copyExpr = CI.getCopyExpr()) {
1100 if (blockDecl->isConversionFromLambda()) {
1101 // If we have a lambda conversion, emit the expression
1102 // directly into the block instead.
1103 AggValueSlot Slot =
1104 AggValueSlot::forAddr(blockField, Qualifiers(),
1105 AggValueSlot::IsDestructed,
1106 AggValueSlot::DoesNotNeedGCBarriers,
1107 AggValueSlot::IsNotAliased,
1108 AggValueSlot::DoesNotOverlap);
1109 EmitAggExpr(copyExpr, Slot);
1110 } else {
1111 EmitSynthesizedCXXCopyCtor(blockField, src, copyExpr);
1112 }
1113
1114 // If it's a reference variable, copy the reference into the block field.
1115 } else if (type->isReferenceType()) {
1116 Builder.CreateStore(src.getPointer(), blockField);
1117
1118 // If type is const-qualified, copy the value into the block field.
1119 } else if (type.isConstQualified() &&
1120 type.getObjCLifetime() == Qualifiers::OCL_Strong &&
1121 CGM.getCodeGenOpts().OptimizationLevel != 0) {
1122 llvm::Value *value = Builder.CreateLoad(src, "captured");
1123 Builder.CreateStore(value, blockField);
1124
1125 // If this is an ARC __strong block-pointer variable, don't do a
1126 // block copy.
1127 //
1128 // TODO: this can be generalized into the normal initialization logic:
1129 // we should never need to do a block-copy when initializing a local
1130 // variable, because the local variable's lifetime should be strictly
1131 // contained within the stack block's.
1132 } else if (type.getObjCLifetime() == Qualifiers::OCL_Strong &&
1133 type->isBlockPointerType()) {
1134 // Load the block and do a simple retain.
1135 llvm::Value *value = Builder.CreateLoad(src, "block.captured_block");
1136 value = EmitARCRetainNonBlock(value);
1137
1138 // Do a primitive store to the block field.
1139 Builder.CreateStore(value, blockField);
1140
1141 // Otherwise, fake up a POD copy into the block field.
1142 } else {
1143 // Fake up a new variable so that EmitScalarInit doesn't think
1144 // we're referring to the variable in its own initializer.
1145 ImplicitParamDecl BlockFieldPseudoVar(getContext(), type,
1146 ImplicitParamDecl::Other);
1147
1148 // We use one of these or the other depending on whether the
1149 // reference is nested.
1150 DeclRefExpr declRef(getContext(), const_cast<VarDecl *>(variable),
1151 /*RefersToEnclosingVariableOrCapture*/ CI.isNested(),
1152 type, VK_LValue, SourceLocation());
1153
1154 ImplicitCastExpr l2r(ImplicitCastExpr::OnStack, type, CK_LValueToRValue,
1155 &declRef, VK_RValue);
1156 // FIXME: Pass a specific location for the expr init so that the store is
1157 // attributed to a reasonable location - otherwise it may be attributed to
1158 // locations of subexpressions in the initialization.
1159 EmitExprAsInit(&l2r, &BlockFieldPseudoVar,
1160 MakeAddrLValue(blockField, type, AlignmentSource::Decl),
1161 /*captured by init*/ false);
1162 }
1163
1164 // Activate the cleanup if layout pushed one.
1165 if (!CI.isByRef()) {
1166 EHScopeStack::stable_iterator cleanup = capture.getCleanup();
1167 if (cleanup.isValid())
1168 ActivateCleanupBlock(cleanup, blockInfo.DominatingIP);
1169 }
1170 }
1171
1172 // Cast to the converted block-pointer type, which happens (somewhat
1173 // unfortunately) to be a pointer to function type.
1174 llvm::Value *result = Builder.CreatePointerCast(
1175 blockAddr.getPointer(), ConvertType(blockInfo.getBlockExpr()->getType()));
1176
1177 if (IsOpenCL) {
1178 CGM.getOpenCLRuntime().recordBlockInfo(blockInfo.BlockExpression, InvokeFn,
1179 result);
1180 }
1181
1182 return result;
1183 }
1184
1185
getBlockDescriptorType()1186 llvm::Type *CodeGenModule::getBlockDescriptorType() {
1187 if (BlockDescriptorType)
1188 return BlockDescriptorType;
1189
1190 llvm::Type *UnsignedLongTy =
1191 getTypes().ConvertType(getContext().UnsignedLongTy);
1192
1193 // struct __block_descriptor {
1194 // unsigned long reserved;
1195 // unsigned long block_size;
1196 //
1197 // // later, the following will be added
1198 //
1199 // struct {
1200 // void (*copyHelper)();
1201 // void (*copyHelper)();
1202 // } helpers; // !!! optional
1203 //
1204 // const char *signature; // the block signature
1205 // const char *layout; // reserved
1206 // };
1207 BlockDescriptorType = llvm::StructType::create(
1208 "struct.__block_descriptor", UnsignedLongTy, UnsignedLongTy);
1209
1210 // Now form a pointer to that.
1211 unsigned AddrSpace = 0;
1212 if (getLangOpts().OpenCL)
1213 AddrSpace = getContext().getTargetAddressSpace(LangAS::opencl_constant);
1214 BlockDescriptorType = llvm::PointerType::get(BlockDescriptorType, AddrSpace);
1215 return BlockDescriptorType;
1216 }
1217
getGenericBlockLiteralType()1218 llvm::Type *CodeGenModule::getGenericBlockLiteralType() {
1219 if (GenericBlockLiteralType)
1220 return GenericBlockLiteralType;
1221
1222 llvm::Type *BlockDescPtrTy = getBlockDescriptorType();
1223
1224 if (getLangOpts().OpenCL) {
1225 // struct __opencl_block_literal_generic {
1226 // int __size;
1227 // int __align;
1228 // __generic void *__invoke;
1229 // /* custom fields */
1230 // };
1231 SmallVector<llvm::Type *, 8> StructFields(
1232 {IntTy, IntTy, getOpenCLRuntime().getGenericVoidPointerType()});
1233 if (auto *Helper = getTargetCodeGenInfo().getTargetOpenCLBlockHelper()) {
1234 for (auto I : Helper->getCustomFieldTypes())
1235 StructFields.push_back(I);
1236 }
1237 GenericBlockLiteralType = llvm::StructType::create(
1238 StructFields, "struct.__opencl_block_literal_generic");
1239 } else {
1240 // struct __block_literal_generic {
1241 // void *__isa;
1242 // int __flags;
1243 // int __reserved;
1244 // void (*__invoke)(void *);
1245 // struct __block_descriptor *__descriptor;
1246 // };
1247 GenericBlockLiteralType =
1248 llvm::StructType::create("struct.__block_literal_generic", VoidPtrTy,
1249 IntTy, IntTy, VoidPtrTy, BlockDescPtrTy);
1250 }
1251
1252 return GenericBlockLiteralType;
1253 }
1254
EmitBlockCallExpr(const CallExpr * E,ReturnValueSlot ReturnValue)1255 RValue CodeGenFunction::EmitBlockCallExpr(const CallExpr *E,
1256 ReturnValueSlot ReturnValue) {
1257 const auto *BPT = E->getCallee()->getType()->castAs<BlockPointerType>();
1258 llvm::Value *BlockPtr = EmitScalarExpr(E->getCallee());
1259 llvm::Type *GenBlockTy = CGM.getGenericBlockLiteralType();
1260 llvm::Value *Func = nullptr;
1261 QualType FnType = BPT->getPointeeType();
1262 ASTContext &Ctx = getContext();
1263 CallArgList Args;
1264
1265 if (getLangOpts().OpenCL) {
1266 // For OpenCL, BlockPtr is already casted to generic block literal.
1267
1268 // First argument of a block call is a generic block literal casted to
1269 // generic void pointer, i.e. i8 addrspace(4)*
1270 llvm::Value *BlockDescriptor = Builder.CreatePointerCast(
1271 BlockPtr, CGM.getOpenCLRuntime().getGenericVoidPointerType());
1272 QualType VoidPtrQualTy = Ctx.getPointerType(
1273 Ctx.getAddrSpaceQualType(Ctx.VoidTy, LangAS::opencl_generic));
1274 Args.add(RValue::get(BlockDescriptor), VoidPtrQualTy);
1275 // And the rest of the arguments.
1276 EmitCallArgs(Args, FnType->getAs<FunctionProtoType>(), E->arguments());
1277
1278 // We *can* call the block directly unless it is a function argument.
1279 if (!isa<ParmVarDecl>(E->getCalleeDecl()))
1280 Func = CGM.getOpenCLRuntime().getInvokeFunction(E->getCallee());
1281 else {
1282 llvm::Value *FuncPtr = Builder.CreateStructGEP(GenBlockTy, BlockPtr, 2);
1283 Func = Builder.CreateAlignedLoad(FuncPtr, getPointerAlign());
1284 }
1285 } else {
1286 // Bitcast the block literal to a generic block literal.
1287 BlockPtr = Builder.CreatePointerCast(
1288 BlockPtr, llvm::PointerType::get(GenBlockTy, 0), "block.literal");
1289 // Get pointer to the block invoke function
1290 llvm::Value *FuncPtr = Builder.CreateStructGEP(GenBlockTy, BlockPtr, 3);
1291
1292 // First argument is a block literal casted to a void pointer
1293 BlockPtr = Builder.CreatePointerCast(BlockPtr, VoidPtrTy);
1294 Args.add(RValue::get(BlockPtr), Ctx.VoidPtrTy);
1295 // And the rest of the arguments.
1296 EmitCallArgs(Args, FnType->getAs<FunctionProtoType>(), E->arguments());
1297
1298 // Load the function.
1299 Func = Builder.CreateAlignedLoad(FuncPtr, getPointerAlign());
1300 }
1301
1302 const FunctionType *FuncTy = FnType->castAs<FunctionType>();
1303 const CGFunctionInfo &FnInfo =
1304 CGM.getTypes().arrangeBlockFunctionCall(Args, FuncTy);
1305
1306 // Cast the function pointer to the right type.
1307 llvm::Type *BlockFTy = CGM.getTypes().GetFunctionType(FnInfo);
1308
1309 llvm::Type *BlockFTyPtr = llvm::PointerType::getUnqual(BlockFTy);
1310 Func = Builder.CreatePointerCast(Func, BlockFTyPtr);
1311
1312 // Prepare the callee.
1313 CGCallee Callee(CGCalleeInfo(), Func);
1314
1315 // And call the block.
1316 return EmitCall(FnInfo, Callee, ReturnValue, Args);
1317 }
1318
GetAddrOfBlockDecl(const VarDecl * variable)1319 Address CodeGenFunction::GetAddrOfBlockDecl(const VarDecl *variable) {
1320 assert(BlockInfo && "evaluating block ref without block information?");
1321 const CGBlockInfo::Capture &capture = BlockInfo->getCapture(variable);
1322
1323 // Handle constant captures.
1324 if (capture.isConstant()) return LocalDeclMap.find(variable)->second;
1325
1326 Address addr = Builder.CreateStructGEP(LoadBlockStruct(), capture.getIndex(),
1327 "block.capture.addr");
1328
1329 if (variable->isEscapingByref()) {
1330 // addr should be a void** right now. Load, then cast the result
1331 // to byref*.
1332
1333 auto &byrefInfo = getBlockByrefInfo(variable);
1334 addr = Address(Builder.CreateLoad(addr), byrefInfo.ByrefAlignment);
1335
1336 auto byrefPointerType = llvm::PointerType::get(byrefInfo.Type, 0);
1337 addr = Builder.CreateBitCast(addr, byrefPointerType, "byref.addr");
1338
1339 addr = emitBlockByrefAddress(addr, byrefInfo, /*follow*/ true,
1340 variable->getName());
1341 }
1342
1343 assert((!variable->isNonEscapingByref() ||
1344 capture.fieldType()->isReferenceType()) &&
1345 "the capture field of a non-escaping variable should have a "
1346 "reference type");
1347 if (capture.fieldType()->isReferenceType())
1348 addr = EmitLoadOfReference(MakeAddrLValue(addr, capture.fieldType()));
1349
1350 return addr;
1351 }
1352
setAddrOfGlobalBlock(const BlockExpr * BE,llvm::Constant * Addr)1353 void CodeGenModule::setAddrOfGlobalBlock(const BlockExpr *BE,
1354 llvm::Constant *Addr) {
1355 bool Ok = EmittedGlobalBlocks.insert(std::make_pair(BE, Addr)).second;
1356 (void)Ok;
1357 assert(Ok && "Trying to replace an already-existing global block!");
1358 }
1359
1360 llvm::Constant *
GetAddrOfGlobalBlock(const BlockExpr * BE,StringRef Name)1361 CodeGenModule::GetAddrOfGlobalBlock(const BlockExpr *BE,
1362 StringRef Name) {
1363 if (llvm::Constant *Block = getAddrOfGlobalBlockIfEmitted(BE))
1364 return Block;
1365
1366 CGBlockInfo blockInfo(BE->getBlockDecl(), Name);
1367 blockInfo.BlockExpression = BE;
1368
1369 // Compute information about the layout, etc., of this block.
1370 computeBlockInfo(*this, nullptr, blockInfo);
1371
1372 // Using that metadata, generate the actual block function.
1373 {
1374 CodeGenFunction::DeclMapTy LocalDeclMap;
1375 CodeGenFunction(*this).GenerateBlockFunction(
1376 GlobalDecl(), blockInfo, LocalDeclMap,
1377 /*IsLambdaConversionToBlock*/ false, /*BuildGlobalBlock*/ true);
1378 }
1379
1380 return getAddrOfGlobalBlockIfEmitted(BE);
1381 }
1382
buildGlobalBlock(CodeGenModule & CGM,const CGBlockInfo & blockInfo,llvm::Constant * blockFn)1383 static llvm::Constant *buildGlobalBlock(CodeGenModule &CGM,
1384 const CGBlockInfo &blockInfo,
1385 llvm::Constant *blockFn) {
1386 assert(blockInfo.CanBeGlobal);
1387 // Callers should detect this case on their own: calling this function
1388 // generally requires computing layout information, which is a waste of time
1389 // if we've already emitted this block.
1390 assert(!CGM.getAddrOfGlobalBlockIfEmitted(blockInfo.BlockExpression) &&
1391 "Refusing to re-emit a global block.");
1392
1393 // Generate the constants for the block literal initializer.
1394 ConstantInitBuilder builder(CGM);
1395 auto fields = builder.beginStruct();
1396
1397 bool IsOpenCL = CGM.getLangOpts().OpenCL;
1398 bool IsWindows = CGM.getTarget().getTriple().isOSWindows();
1399 if (!IsOpenCL) {
1400 // isa
1401 if (IsWindows)
1402 fields.addNullPointer(CGM.Int8PtrPtrTy);
1403 else
1404 fields.add(CGM.getNSConcreteGlobalBlock());
1405
1406 // __flags
1407 BlockFlags flags = BLOCK_IS_GLOBAL | BLOCK_HAS_SIGNATURE;
1408 if (blockInfo.UsesStret)
1409 flags |= BLOCK_USE_STRET;
1410
1411 fields.addInt(CGM.IntTy, flags.getBitMask());
1412
1413 // Reserved
1414 fields.addInt(CGM.IntTy, 0);
1415 } else {
1416 fields.addInt(CGM.IntTy, blockInfo.BlockSize.getQuantity());
1417 fields.addInt(CGM.IntTy, blockInfo.BlockAlign.getQuantity());
1418 }
1419
1420 // Function
1421 fields.add(blockFn);
1422
1423 if (!IsOpenCL) {
1424 // Descriptor
1425 fields.add(buildBlockDescriptor(CGM, blockInfo));
1426 } else if (auto *Helper =
1427 CGM.getTargetCodeGenInfo().getTargetOpenCLBlockHelper()) {
1428 for (auto I : Helper->getCustomFieldValues(CGM, blockInfo)) {
1429 fields.add(I);
1430 }
1431 }
1432
1433 unsigned AddrSpace = 0;
1434 if (CGM.getContext().getLangOpts().OpenCL)
1435 AddrSpace = CGM.getContext().getTargetAddressSpace(LangAS::opencl_global);
1436
1437 llvm::GlobalVariable *literal = fields.finishAndCreateGlobal(
1438 "__block_literal_global", blockInfo.BlockAlign,
1439 /*constant*/ !IsWindows, llvm::GlobalVariable::InternalLinkage, AddrSpace);
1440
1441 literal->addAttribute("objc_arc_inert");
1442
1443 // Windows does not allow globals to be initialised to point to globals in
1444 // different DLLs. Any such variables must run code to initialise them.
1445 if (IsWindows) {
1446 auto *Init = llvm::Function::Create(llvm::FunctionType::get(CGM.VoidTy,
1447 {}), llvm::GlobalValue::InternalLinkage, ".block_isa_init",
1448 &CGM.getModule());
1449 llvm::IRBuilder<> b(llvm::BasicBlock::Create(CGM.getLLVMContext(), "entry",
1450 Init));
1451 b.CreateAlignedStore(CGM.getNSConcreteGlobalBlock(),
1452 b.CreateStructGEP(literal, 0), CGM.getPointerAlign().getQuantity());
1453 b.CreateRetVoid();
1454 // We can't use the normal LLVM global initialisation array, because we
1455 // need to specify that this runs early in library initialisation.
1456 auto *InitVar = new llvm::GlobalVariable(CGM.getModule(), Init->getType(),
1457 /*isConstant*/true, llvm::GlobalValue::InternalLinkage,
1458 Init, ".block_isa_init_ptr");
1459 InitVar->setSection(".CRT$XCLa");
1460 CGM.addUsedGlobal(InitVar);
1461 }
1462
1463 // Return a constant of the appropriately-casted type.
1464 llvm::Type *RequiredType =
1465 CGM.getTypes().ConvertType(blockInfo.getBlockExpr()->getType());
1466 llvm::Constant *Result =
1467 llvm::ConstantExpr::getPointerCast(literal, RequiredType);
1468 CGM.setAddrOfGlobalBlock(blockInfo.BlockExpression, Result);
1469 if (CGM.getContext().getLangOpts().OpenCL)
1470 CGM.getOpenCLRuntime().recordBlockInfo(
1471 blockInfo.BlockExpression,
1472 cast<llvm::Function>(blockFn->stripPointerCasts()), Result);
1473 return Result;
1474 }
1475
setBlockContextParameter(const ImplicitParamDecl * D,unsigned argNum,llvm::Value * arg)1476 void CodeGenFunction::setBlockContextParameter(const ImplicitParamDecl *D,
1477 unsigned argNum,
1478 llvm::Value *arg) {
1479 assert(BlockInfo && "not emitting prologue of block invocation function?!");
1480
1481 // Allocate a stack slot like for any local variable to guarantee optimal
1482 // debug info at -O0. The mem2reg pass will eliminate it when optimizing.
1483 Address alloc = CreateMemTemp(D->getType(), D->getName() + ".addr");
1484 Builder.CreateStore(arg, alloc);
1485 if (CGDebugInfo *DI = getDebugInfo()) {
1486 if (CGM.getCodeGenOpts().hasReducedDebugInfo()) {
1487 DI->setLocation(D->getLocation());
1488 DI->EmitDeclareOfBlockLiteralArgVariable(
1489 *BlockInfo, D->getName(), argNum,
1490 cast<llvm::AllocaInst>(alloc.getPointer()), Builder);
1491 }
1492 }
1493
1494 SourceLocation StartLoc = BlockInfo->getBlockExpr()->getBody()->getBeginLoc();
1495 ApplyDebugLocation Scope(*this, StartLoc);
1496
1497 // Instead of messing around with LocalDeclMap, just set the value
1498 // directly as BlockPointer.
1499 BlockPointer = Builder.CreatePointerCast(
1500 arg,
1501 BlockInfo->StructureType->getPointerTo(
1502 getContext().getLangOpts().OpenCL
1503 ? getContext().getTargetAddressSpace(LangAS::opencl_generic)
1504 : 0),
1505 "block");
1506 }
1507
LoadBlockStruct()1508 Address CodeGenFunction::LoadBlockStruct() {
1509 assert(BlockInfo && "not in a block invocation function!");
1510 assert(BlockPointer && "no block pointer set!");
1511 return Address(BlockPointer, BlockInfo->BlockAlign);
1512 }
1513
1514 llvm::Function *
GenerateBlockFunction(GlobalDecl GD,const CGBlockInfo & blockInfo,const DeclMapTy & ldm,bool IsLambdaConversionToBlock,bool BuildGlobalBlock)1515 CodeGenFunction::GenerateBlockFunction(GlobalDecl GD,
1516 const CGBlockInfo &blockInfo,
1517 const DeclMapTy &ldm,
1518 bool IsLambdaConversionToBlock,
1519 bool BuildGlobalBlock) {
1520 const BlockDecl *blockDecl = blockInfo.getBlockDecl();
1521
1522 CurGD = GD;
1523
1524 CurEHLocation = blockInfo.getBlockExpr()->getEndLoc();
1525
1526 BlockInfo = &blockInfo;
1527
1528 // Arrange for local static and local extern declarations to appear
1529 // to be local to this function as well, in case they're directly
1530 // referenced in a block.
1531 for (DeclMapTy::const_iterator i = ldm.begin(), e = ldm.end(); i != e; ++i) {
1532 const auto *var = dyn_cast<VarDecl>(i->first);
1533 if (var && !var->hasLocalStorage())
1534 setAddrOfLocalVar(var, i->second);
1535 }
1536
1537 // Begin building the function declaration.
1538
1539 // Build the argument list.
1540 FunctionArgList args;
1541
1542 // The first argument is the block pointer. Just take it as a void*
1543 // and cast it later.
1544 QualType selfTy = getContext().VoidPtrTy;
1545
1546 // For OpenCL passed block pointer can be private AS local variable or
1547 // global AS program scope variable (for the case with and without captures).
1548 // Generic AS is used therefore to be able to accommodate both private and
1549 // generic AS in one implementation.
1550 if (getLangOpts().OpenCL)
1551 selfTy = getContext().getPointerType(getContext().getAddrSpaceQualType(
1552 getContext().VoidTy, LangAS::opencl_generic));
1553
1554 IdentifierInfo *II = &CGM.getContext().Idents.get(".block_descriptor");
1555
1556 ImplicitParamDecl SelfDecl(getContext(), const_cast<BlockDecl *>(blockDecl),
1557 SourceLocation(), II, selfTy,
1558 ImplicitParamDecl::ObjCSelf);
1559 args.push_back(&SelfDecl);
1560
1561 // Now add the rest of the parameters.
1562 args.append(blockDecl->param_begin(), blockDecl->param_end());
1563
1564 // Create the function declaration.
1565 const FunctionProtoType *fnType = blockInfo.getBlockExpr()->getFunctionType();
1566 const CGFunctionInfo &fnInfo =
1567 CGM.getTypes().arrangeBlockFunctionDeclaration(fnType, args);
1568 if (CGM.ReturnSlotInterferesWithArgs(fnInfo))
1569 blockInfo.UsesStret = true;
1570
1571 llvm::FunctionType *fnLLVMType = CGM.getTypes().GetFunctionType(fnInfo);
1572
1573 StringRef name = CGM.getBlockMangledName(GD, blockDecl);
1574 llvm::Function *fn = llvm::Function::Create(
1575 fnLLVMType, llvm::GlobalValue::InternalLinkage, name, &CGM.getModule());
1576 CGM.SetInternalFunctionAttributes(blockDecl, fn, fnInfo);
1577
1578 if (BuildGlobalBlock) {
1579 auto GenVoidPtrTy = getContext().getLangOpts().OpenCL
1580 ? CGM.getOpenCLRuntime().getGenericVoidPointerType()
1581 : VoidPtrTy;
1582 buildGlobalBlock(CGM, blockInfo,
1583 llvm::ConstantExpr::getPointerCast(fn, GenVoidPtrTy));
1584 }
1585
1586 // Begin generating the function.
1587 StartFunction(blockDecl, fnType->getReturnType(), fn, fnInfo, args,
1588 blockDecl->getLocation(),
1589 blockInfo.getBlockExpr()->getBody()->getBeginLoc());
1590
1591 // Okay. Undo some of what StartFunction did.
1592
1593 // At -O0 we generate an explicit alloca for the BlockPointer, so the RA
1594 // won't delete the dbg.declare intrinsics for captured variables.
1595 llvm::Value *BlockPointerDbgLoc = BlockPointer;
1596 if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
1597 // Allocate a stack slot for it, so we can point the debugger to it
1598 Address Alloca = CreateTempAlloca(BlockPointer->getType(),
1599 getPointerAlign(),
1600 "block.addr");
1601 // Set the DebugLocation to empty, so the store is recognized as a
1602 // frame setup instruction by llvm::DwarfDebug::beginFunction().
1603 auto NL = ApplyDebugLocation::CreateEmpty(*this);
1604 Builder.CreateStore(BlockPointer, Alloca);
1605 BlockPointerDbgLoc = Alloca.getPointer();
1606 }
1607
1608 // If we have a C++ 'this' reference, go ahead and force it into
1609 // existence now.
1610 if (blockDecl->capturesCXXThis()) {
1611 Address addr = Builder.CreateStructGEP(
1612 LoadBlockStruct(), blockInfo.CXXThisIndex, "block.captured-this");
1613 CXXThisValue = Builder.CreateLoad(addr, "this");
1614 }
1615
1616 // Also force all the constant captures.
1617 for (const auto &CI : blockDecl->captures()) {
1618 const VarDecl *variable = CI.getVariable();
1619 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
1620 if (!capture.isConstant()) continue;
1621
1622 CharUnits align = getContext().getDeclAlign(variable);
1623 Address alloca =
1624 CreateMemTemp(variable->getType(), align, "block.captured-const");
1625
1626 Builder.CreateStore(capture.getConstant(), alloca);
1627
1628 setAddrOfLocalVar(variable, alloca);
1629 }
1630
1631 // Save a spot to insert the debug information for all the DeclRefExprs.
1632 llvm::BasicBlock *entry = Builder.GetInsertBlock();
1633 llvm::BasicBlock::iterator entry_ptr = Builder.GetInsertPoint();
1634 --entry_ptr;
1635
1636 if (IsLambdaConversionToBlock)
1637 EmitLambdaBlockInvokeBody();
1638 else {
1639 PGO.assignRegionCounters(GlobalDecl(blockDecl), fn);
1640 incrementProfileCounter(blockDecl->getBody());
1641 EmitStmt(blockDecl->getBody());
1642 }
1643
1644 // Remember where we were...
1645 llvm::BasicBlock *resume = Builder.GetInsertBlock();
1646
1647 // Go back to the entry.
1648 ++entry_ptr;
1649 Builder.SetInsertPoint(entry, entry_ptr);
1650
1651 // Emit debug information for all the DeclRefExprs.
1652 // FIXME: also for 'this'
1653 if (CGDebugInfo *DI = getDebugInfo()) {
1654 for (const auto &CI : blockDecl->captures()) {
1655 const VarDecl *variable = CI.getVariable();
1656 DI->EmitLocation(Builder, variable->getLocation());
1657
1658 if (CGM.getCodeGenOpts().hasReducedDebugInfo()) {
1659 const CGBlockInfo::Capture &capture = blockInfo.getCapture(variable);
1660 if (capture.isConstant()) {
1661 auto addr = LocalDeclMap.find(variable)->second;
1662 (void)DI->EmitDeclareOfAutoVariable(variable, addr.getPointer(),
1663 Builder);
1664 continue;
1665 }
1666
1667 DI->EmitDeclareOfBlockDeclRefVariable(
1668 variable, BlockPointerDbgLoc, Builder, blockInfo,
1669 entry_ptr == entry->end() ? nullptr : &*entry_ptr);
1670 }
1671 }
1672 // Recover location if it was changed in the above loop.
1673 DI->EmitLocation(Builder,
1674 cast<CompoundStmt>(blockDecl->getBody())->getRBracLoc());
1675 }
1676
1677 // And resume where we left off.
1678 if (resume == nullptr)
1679 Builder.ClearInsertionPoint();
1680 else
1681 Builder.SetInsertPoint(resume);
1682
1683 FinishFunction(cast<CompoundStmt>(blockDecl->getBody())->getRBracLoc());
1684
1685 return fn;
1686 }
1687
1688 static std::pair<BlockCaptureEntityKind, BlockFieldFlags>
computeCopyInfoForBlockCapture(const BlockDecl::Capture & CI,QualType T,const LangOptions & LangOpts)1689 computeCopyInfoForBlockCapture(const BlockDecl::Capture &CI, QualType T,
1690 const LangOptions &LangOpts) {
1691 if (CI.getCopyExpr()) {
1692 assert(!CI.isByRef());
1693 // don't bother computing flags
1694 return std::make_pair(BlockCaptureEntityKind::CXXRecord, BlockFieldFlags());
1695 }
1696 BlockFieldFlags Flags;
1697 if (CI.isEscapingByref()) {
1698 Flags = BLOCK_FIELD_IS_BYREF;
1699 if (T.isObjCGCWeak())
1700 Flags |= BLOCK_FIELD_IS_WEAK;
1701 return std::make_pair(BlockCaptureEntityKind::BlockObject, Flags);
1702 }
1703
1704 Flags = BLOCK_FIELD_IS_OBJECT;
1705 bool isBlockPointer = T->isBlockPointerType();
1706 if (isBlockPointer)
1707 Flags = BLOCK_FIELD_IS_BLOCK;
1708
1709 switch (T.isNonTrivialToPrimitiveCopy()) {
1710 case QualType::PCK_Struct:
1711 return std::make_pair(BlockCaptureEntityKind::NonTrivialCStruct,
1712 BlockFieldFlags());
1713 case QualType::PCK_ARCWeak:
1714 // We need to register __weak direct captures with the runtime.
1715 return std::make_pair(BlockCaptureEntityKind::ARCWeak, Flags);
1716 case QualType::PCK_ARCStrong:
1717 // We need to retain the copied value for __strong direct captures.
1718 // If it's a block pointer, we have to copy the block and assign that to
1719 // the destination pointer, so we might as well use _Block_object_assign.
1720 // Otherwise we can avoid that.
1721 return std::make_pair(!isBlockPointer ? BlockCaptureEntityKind::ARCStrong
1722 : BlockCaptureEntityKind::BlockObject,
1723 Flags);
1724 case QualType::PCK_Trivial:
1725 case QualType::PCK_VolatileTrivial: {
1726 if (!T->isObjCRetainableType())
1727 // For all other types, the memcpy is fine.
1728 return std::make_pair(BlockCaptureEntityKind::None, BlockFieldFlags());
1729
1730 // Special rules for ARC captures:
1731 Qualifiers QS = T.getQualifiers();
1732
1733 // Non-ARC captures of retainable pointers are strong and
1734 // therefore require a call to _Block_object_assign.
1735 if (!QS.getObjCLifetime() && !LangOpts.ObjCAutoRefCount)
1736 return std::make_pair(BlockCaptureEntityKind::BlockObject, Flags);
1737
1738 // Otherwise the memcpy is fine.
1739 return std::make_pair(BlockCaptureEntityKind::None, BlockFieldFlags());
1740 }
1741 }
1742 llvm_unreachable("after exhaustive PrimitiveCopyKind switch");
1743 }
1744
1745 static std::pair<BlockCaptureEntityKind, BlockFieldFlags>
1746 computeDestroyInfoForBlockCapture(const BlockDecl::Capture &CI, QualType T,
1747 const LangOptions &LangOpts);
1748
1749 /// Find the set of block captures that need to be explicitly copied or destroy.
findBlockCapturedManagedEntities(const CGBlockInfo & BlockInfo,const LangOptions & LangOpts,SmallVectorImpl<BlockCaptureManagedEntity> & ManagedCaptures)1750 static void findBlockCapturedManagedEntities(
1751 const CGBlockInfo &BlockInfo, const LangOptions &LangOpts,
1752 SmallVectorImpl<BlockCaptureManagedEntity> &ManagedCaptures) {
1753 for (const auto &CI : BlockInfo.getBlockDecl()->captures()) {
1754 const VarDecl *Variable = CI.getVariable();
1755 const CGBlockInfo::Capture &Capture = BlockInfo.getCapture(Variable);
1756 if (Capture.isConstant())
1757 continue;
1758
1759 QualType VT = Capture.fieldType();
1760 auto CopyInfo = computeCopyInfoForBlockCapture(CI, VT, LangOpts);
1761 auto DisposeInfo = computeDestroyInfoForBlockCapture(CI, VT, LangOpts);
1762 if (CopyInfo.first != BlockCaptureEntityKind::None ||
1763 DisposeInfo.first != BlockCaptureEntityKind::None)
1764 ManagedCaptures.emplace_back(CopyInfo.first, DisposeInfo.first,
1765 CopyInfo.second, DisposeInfo.second, CI,
1766 Capture);
1767 }
1768
1769 // Sort the captures by offset.
1770 llvm::sort(ManagedCaptures);
1771 }
1772
1773 namespace {
1774 /// Release a __block variable.
1775 struct CallBlockRelease final : EHScopeStack::Cleanup {
1776 Address Addr;
1777 BlockFieldFlags FieldFlags;
1778 bool LoadBlockVarAddr, CanThrow;
1779
CallBlockRelease__anon5c6b972f0711::CallBlockRelease1780 CallBlockRelease(Address Addr, BlockFieldFlags Flags, bool LoadValue,
1781 bool CT)
1782 : Addr(Addr), FieldFlags(Flags), LoadBlockVarAddr(LoadValue),
1783 CanThrow(CT) {}
1784
Emit__anon5c6b972f0711::CallBlockRelease1785 void Emit(CodeGenFunction &CGF, Flags flags) override {
1786 llvm::Value *BlockVarAddr;
1787 if (LoadBlockVarAddr) {
1788 BlockVarAddr = CGF.Builder.CreateLoad(Addr);
1789 BlockVarAddr = CGF.Builder.CreateBitCast(BlockVarAddr, CGF.VoidPtrTy);
1790 } else {
1791 BlockVarAddr = Addr.getPointer();
1792 }
1793
1794 CGF.BuildBlockRelease(BlockVarAddr, FieldFlags, CanThrow);
1795 }
1796 };
1797 } // end anonymous namespace
1798
1799 /// Check if \p T is a C++ class that has a destructor that can throw.
cxxDestructorCanThrow(QualType T)1800 bool CodeGenFunction::cxxDestructorCanThrow(QualType T) {
1801 if (const auto *RD = T->getAsCXXRecordDecl())
1802 if (const CXXDestructorDecl *DD = RD->getDestructor())
1803 return DD->getType()->castAs<FunctionProtoType>()->canThrow();
1804 return false;
1805 }
1806
1807 // Return a string that has the information about a capture.
getBlockCaptureStr(const BlockCaptureManagedEntity & E,CaptureStrKind StrKind,CharUnits BlockAlignment,CodeGenModule & CGM)1808 static std::string getBlockCaptureStr(const BlockCaptureManagedEntity &E,
1809 CaptureStrKind StrKind,
1810 CharUnits BlockAlignment,
1811 CodeGenModule &CGM) {
1812 std::string Str;
1813 ASTContext &Ctx = CGM.getContext();
1814 const BlockDecl::Capture &CI = *E.CI;
1815 QualType CaptureTy = CI.getVariable()->getType();
1816
1817 BlockCaptureEntityKind Kind;
1818 BlockFieldFlags Flags;
1819
1820 // CaptureStrKind::Merged should be passed only when the operations and the
1821 // flags are the same for copy and dispose.
1822 assert((StrKind != CaptureStrKind::Merged ||
1823 (E.CopyKind == E.DisposeKind && E.CopyFlags == E.DisposeFlags)) &&
1824 "different operations and flags");
1825
1826 if (StrKind == CaptureStrKind::DisposeHelper) {
1827 Kind = E.DisposeKind;
1828 Flags = E.DisposeFlags;
1829 } else {
1830 Kind = E.CopyKind;
1831 Flags = E.CopyFlags;
1832 }
1833
1834 switch (Kind) {
1835 case BlockCaptureEntityKind::CXXRecord: {
1836 Str += "c";
1837 SmallString<256> TyStr;
1838 llvm::raw_svector_ostream Out(TyStr);
1839 CGM.getCXXABI().getMangleContext().mangleTypeName(CaptureTy, Out);
1840 Str += llvm::to_string(TyStr.size()) + TyStr.c_str();
1841 break;
1842 }
1843 case BlockCaptureEntityKind::ARCWeak:
1844 Str += "w";
1845 break;
1846 case BlockCaptureEntityKind::ARCStrong:
1847 Str += "s";
1848 break;
1849 case BlockCaptureEntityKind::BlockObject: {
1850 const VarDecl *Var = CI.getVariable();
1851 unsigned F = Flags.getBitMask();
1852 if (F & BLOCK_FIELD_IS_BYREF) {
1853 Str += "r";
1854 if (F & BLOCK_FIELD_IS_WEAK)
1855 Str += "w";
1856 else {
1857 // If CaptureStrKind::Merged is passed, check both the copy expression
1858 // and the destructor.
1859 if (StrKind != CaptureStrKind::DisposeHelper) {
1860 if (Ctx.getBlockVarCopyInit(Var).canThrow())
1861 Str += "c";
1862 }
1863 if (StrKind != CaptureStrKind::CopyHelper) {
1864 if (CodeGenFunction::cxxDestructorCanThrow(CaptureTy))
1865 Str += "d";
1866 }
1867 }
1868 } else {
1869 assert((F & BLOCK_FIELD_IS_OBJECT) && "unexpected flag value");
1870 if (F == BLOCK_FIELD_IS_BLOCK)
1871 Str += "b";
1872 else
1873 Str += "o";
1874 }
1875 break;
1876 }
1877 case BlockCaptureEntityKind::NonTrivialCStruct: {
1878 bool IsVolatile = CaptureTy.isVolatileQualified();
1879 CharUnits Alignment =
1880 BlockAlignment.alignmentAtOffset(E.Capture->getOffset());
1881
1882 Str += "n";
1883 std::string FuncStr;
1884 if (StrKind == CaptureStrKind::DisposeHelper)
1885 FuncStr = CodeGenFunction::getNonTrivialDestructorStr(
1886 CaptureTy, Alignment, IsVolatile, Ctx);
1887 else
1888 // If CaptureStrKind::Merged is passed, use the copy constructor string.
1889 // It has all the information that the destructor string has.
1890 FuncStr = CodeGenFunction::getNonTrivialCopyConstructorStr(
1891 CaptureTy, Alignment, IsVolatile, Ctx);
1892 // The underscore is necessary here because non-trivial copy constructor
1893 // and destructor strings can start with a number.
1894 Str += llvm::to_string(FuncStr.size()) + "_" + FuncStr;
1895 break;
1896 }
1897 case BlockCaptureEntityKind::None:
1898 break;
1899 }
1900
1901 return Str;
1902 }
1903
getCopyDestroyHelperFuncName(const SmallVectorImpl<BlockCaptureManagedEntity> & Captures,CharUnits BlockAlignment,CaptureStrKind StrKind,CodeGenModule & CGM)1904 static std::string getCopyDestroyHelperFuncName(
1905 const SmallVectorImpl<BlockCaptureManagedEntity> &Captures,
1906 CharUnits BlockAlignment, CaptureStrKind StrKind, CodeGenModule &CGM) {
1907 assert((StrKind == CaptureStrKind::CopyHelper ||
1908 StrKind == CaptureStrKind::DisposeHelper) &&
1909 "unexpected CaptureStrKind");
1910 std::string Name = StrKind == CaptureStrKind::CopyHelper
1911 ? "__copy_helper_block_"
1912 : "__destroy_helper_block_";
1913 if (CGM.getLangOpts().Exceptions)
1914 Name += "e";
1915 if (CGM.getCodeGenOpts().ObjCAutoRefCountExceptions)
1916 Name += "a";
1917 Name += llvm::to_string(BlockAlignment.getQuantity()) + "_";
1918
1919 for (const BlockCaptureManagedEntity &E : Captures) {
1920 Name += llvm::to_string(E.Capture->getOffset().getQuantity());
1921 Name += getBlockCaptureStr(E, StrKind, BlockAlignment, CGM);
1922 }
1923
1924 return Name;
1925 }
1926
pushCaptureCleanup(BlockCaptureEntityKind CaptureKind,Address Field,QualType CaptureType,BlockFieldFlags Flags,bool ForCopyHelper,VarDecl * Var,CodeGenFunction & CGF)1927 static void pushCaptureCleanup(BlockCaptureEntityKind CaptureKind,
1928 Address Field, QualType CaptureType,
1929 BlockFieldFlags Flags, bool ForCopyHelper,
1930 VarDecl *Var, CodeGenFunction &CGF) {
1931 bool EHOnly = ForCopyHelper;
1932
1933 switch (CaptureKind) {
1934 case BlockCaptureEntityKind::CXXRecord:
1935 case BlockCaptureEntityKind::ARCWeak:
1936 case BlockCaptureEntityKind::NonTrivialCStruct:
1937 case BlockCaptureEntityKind::ARCStrong: {
1938 if (CaptureType.isDestructedType() &&
1939 (!EHOnly || CGF.needsEHCleanup(CaptureType.isDestructedType()))) {
1940 CodeGenFunction::Destroyer *Destroyer =
1941 CaptureKind == BlockCaptureEntityKind::ARCStrong
1942 ? CodeGenFunction::destroyARCStrongImprecise
1943 : CGF.getDestroyer(CaptureType.isDestructedType());
1944 CleanupKind Kind =
1945 EHOnly ? EHCleanup
1946 : CGF.getCleanupKind(CaptureType.isDestructedType());
1947 CGF.pushDestroy(Kind, Field, CaptureType, Destroyer, Kind & EHCleanup);
1948 }
1949 break;
1950 }
1951 case BlockCaptureEntityKind::BlockObject: {
1952 if (!EHOnly || CGF.getLangOpts().Exceptions) {
1953 CleanupKind Kind = EHOnly ? EHCleanup : NormalAndEHCleanup;
1954 // Calls to _Block_object_dispose along the EH path in the copy helper
1955 // function don't throw as newly-copied __block variables always have a
1956 // reference count of 2.
1957 bool CanThrow =
1958 !ForCopyHelper && CGF.cxxDestructorCanThrow(CaptureType);
1959 CGF.enterByrefCleanup(Kind, Field, Flags, /*LoadBlockVarAddr*/ true,
1960 CanThrow);
1961 }
1962 break;
1963 }
1964 case BlockCaptureEntityKind::None:
1965 break;
1966 }
1967 }
1968
setBlockHelperAttributesVisibility(bool CapturesNonExternalType,llvm::Function * Fn,const CGFunctionInfo & FI,CodeGenModule & CGM)1969 static void setBlockHelperAttributesVisibility(bool CapturesNonExternalType,
1970 llvm::Function *Fn,
1971 const CGFunctionInfo &FI,
1972 CodeGenModule &CGM) {
1973 if (CapturesNonExternalType) {
1974 CGM.SetInternalFunctionAttributes(GlobalDecl(), Fn, FI);
1975 } else {
1976 Fn->setVisibility(llvm::GlobalValue::HiddenVisibility);
1977 Fn->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
1978 CGM.SetLLVMFunctionAttributes(GlobalDecl(), FI, Fn);
1979 CGM.SetLLVMFunctionAttributesForDefinition(nullptr, Fn);
1980 }
1981 }
1982 /// Generate the copy-helper function for a block closure object:
1983 /// static void block_copy_helper(block_t *dst, block_t *src);
1984 /// The runtime will have previously initialized 'dst' by doing a
1985 /// bit-copy of 'src'.
1986 ///
1987 /// Note that this copies an entire block closure object to the heap;
1988 /// it should not be confused with a 'byref copy helper', which moves
1989 /// the contents of an individual __block variable to the heap.
1990 llvm::Constant *
GenerateCopyHelperFunction(const CGBlockInfo & blockInfo)1991 CodeGenFunction::GenerateCopyHelperFunction(const CGBlockInfo &blockInfo) {
1992 SmallVector<BlockCaptureManagedEntity, 4> CopiedCaptures;
1993 findBlockCapturedManagedEntities(blockInfo, getLangOpts(), CopiedCaptures);
1994 std::string FuncName =
1995 getCopyDestroyHelperFuncName(CopiedCaptures, blockInfo.BlockAlign,
1996 CaptureStrKind::CopyHelper, CGM);
1997
1998 if (llvm::GlobalValue *Func = CGM.getModule().getNamedValue(FuncName))
1999 return llvm::ConstantExpr::getBitCast(Func, VoidPtrTy);
2000
2001 ASTContext &C = getContext();
2002
2003 QualType ReturnTy = C.VoidTy;
2004
2005 FunctionArgList args;
2006 ImplicitParamDecl DstDecl(C, C.VoidPtrTy, ImplicitParamDecl::Other);
2007 args.push_back(&DstDecl);
2008 ImplicitParamDecl SrcDecl(C, C.VoidPtrTy, ImplicitParamDecl::Other);
2009 args.push_back(&SrcDecl);
2010
2011 const CGFunctionInfo &FI =
2012 CGM.getTypes().arrangeBuiltinFunctionDeclaration(ReturnTy, args);
2013
2014 // FIXME: it would be nice if these were mergeable with things with
2015 // identical semantics.
2016 llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI);
2017
2018 llvm::Function *Fn =
2019 llvm::Function::Create(LTy, llvm::GlobalValue::LinkOnceODRLinkage,
2020 FuncName, &CGM.getModule());
2021 if (CGM.supportsCOMDAT())
2022 Fn->setComdat(CGM.getModule().getOrInsertComdat(FuncName));
2023
2024 IdentifierInfo *II = &C.Idents.get(FuncName);
2025
2026 SmallVector<QualType, 2> ArgTys;
2027 ArgTys.push_back(C.VoidPtrTy);
2028 ArgTys.push_back(C.VoidPtrTy);
2029 QualType FunctionTy = C.getFunctionType(ReturnTy, ArgTys, {});
2030
2031 FunctionDecl *FD = FunctionDecl::Create(
2032 C, C.getTranslationUnitDecl(), SourceLocation(), SourceLocation(), II,
2033 FunctionTy, nullptr, SC_Static, false, false);
2034
2035 setBlockHelperAttributesVisibility(blockInfo.CapturesNonExternalType, Fn, FI,
2036 CGM);
2037 StartFunction(FD, ReturnTy, Fn, FI, args);
2038 ApplyDebugLocation NL{*this, blockInfo.getBlockExpr()->getBeginLoc()};
2039 llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo();
2040
2041 Address src = GetAddrOfLocalVar(&SrcDecl);
2042 src = Address(Builder.CreateLoad(src), blockInfo.BlockAlign);
2043 src = Builder.CreateBitCast(src, structPtrTy, "block.source");
2044
2045 Address dst = GetAddrOfLocalVar(&DstDecl);
2046 dst = Address(Builder.CreateLoad(dst), blockInfo.BlockAlign);
2047 dst = Builder.CreateBitCast(dst, structPtrTy, "block.dest");
2048
2049 for (const auto &CopiedCapture : CopiedCaptures) {
2050 const BlockDecl::Capture &CI = *CopiedCapture.CI;
2051 const CGBlockInfo::Capture &capture = *CopiedCapture.Capture;
2052 QualType captureType = CI.getVariable()->getType();
2053 BlockFieldFlags flags = CopiedCapture.CopyFlags;
2054
2055 unsigned index = capture.getIndex();
2056 Address srcField = Builder.CreateStructGEP(src, index);
2057 Address dstField = Builder.CreateStructGEP(dst, index);
2058
2059 switch (CopiedCapture.CopyKind) {
2060 case BlockCaptureEntityKind::CXXRecord:
2061 // If there's an explicit copy expression, we do that.
2062 assert(CI.getCopyExpr() && "copy expression for variable is missing");
2063 EmitSynthesizedCXXCopyCtor(dstField, srcField, CI.getCopyExpr());
2064 break;
2065 case BlockCaptureEntityKind::ARCWeak:
2066 EmitARCCopyWeak(dstField, srcField);
2067 break;
2068 case BlockCaptureEntityKind::NonTrivialCStruct: {
2069 // If this is a C struct that requires non-trivial copy construction,
2070 // emit a call to its copy constructor.
2071 QualType varType = CI.getVariable()->getType();
2072 callCStructCopyConstructor(MakeAddrLValue(dstField, varType),
2073 MakeAddrLValue(srcField, varType));
2074 break;
2075 }
2076 case BlockCaptureEntityKind::ARCStrong: {
2077 llvm::Value *srcValue = Builder.CreateLoad(srcField, "blockcopy.src");
2078 // At -O0, store null into the destination field (so that the
2079 // storeStrong doesn't over-release) and then call storeStrong.
2080 // This is a workaround to not having an initStrong call.
2081 if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
2082 auto *ty = cast<llvm::PointerType>(srcValue->getType());
2083 llvm::Value *null = llvm::ConstantPointerNull::get(ty);
2084 Builder.CreateStore(null, dstField);
2085 EmitARCStoreStrongCall(dstField, srcValue, true);
2086
2087 // With optimization enabled, take advantage of the fact that
2088 // the blocks runtime guarantees a memcpy of the block data, and
2089 // just emit a retain of the src field.
2090 } else {
2091 EmitARCRetainNonBlock(srcValue);
2092
2093 // Unless EH cleanup is required, we don't need this anymore, so kill
2094 // it. It's not quite worth the annoyance to avoid creating it in the
2095 // first place.
2096 if (!needsEHCleanup(captureType.isDestructedType()))
2097 cast<llvm::Instruction>(dstField.getPointer())->eraseFromParent();
2098 }
2099 break;
2100 }
2101 case BlockCaptureEntityKind::BlockObject: {
2102 llvm::Value *srcValue = Builder.CreateLoad(srcField, "blockcopy.src");
2103 srcValue = Builder.CreateBitCast(srcValue, VoidPtrTy);
2104 llvm::Value *dstAddr =
2105 Builder.CreateBitCast(dstField.getPointer(), VoidPtrTy);
2106 llvm::Value *args[] = {
2107 dstAddr, srcValue, llvm::ConstantInt::get(Int32Ty, flags.getBitMask())
2108 };
2109
2110 if (CI.isByRef() && C.getBlockVarCopyInit(CI.getVariable()).canThrow())
2111 EmitRuntimeCallOrInvoke(CGM.getBlockObjectAssign(), args);
2112 else
2113 EmitNounwindRuntimeCall(CGM.getBlockObjectAssign(), args);
2114 break;
2115 }
2116 case BlockCaptureEntityKind::None:
2117 continue;
2118 }
2119
2120 // Ensure that we destroy the copied object if an exception is thrown later
2121 // in the helper function.
2122 pushCaptureCleanup(CopiedCapture.CopyKind, dstField, captureType, flags,
2123 /*ForCopyHelper*/ true, CI.getVariable(), *this);
2124 }
2125
2126 FinishFunction();
2127
2128 return llvm::ConstantExpr::getBitCast(Fn, VoidPtrTy);
2129 }
2130
2131 static BlockFieldFlags
getBlockFieldFlagsForObjCObjectPointer(const BlockDecl::Capture & CI,QualType T)2132 getBlockFieldFlagsForObjCObjectPointer(const BlockDecl::Capture &CI,
2133 QualType T) {
2134 BlockFieldFlags Flags = BLOCK_FIELD_IS_OBJECT;
2135 if (T->isBlockPointerType())
2136 Flags = BLOCK_FIELD_IS_BLOCK;
2137 return Flags;
2138 }
2139
2140 static std::pair<BlockCaptureEntityKind, BlockFieldFlags>
computeDestroyInfoForBlockCapture(const BlockDecl::Capture & CI,QualType T,const LangOptions & LangOpts)2141 computeDestroyInfoForBlockCapture(const BlockDecl::Capture &CI, QualType T,
2142 const LangOptions &LangOpts) {
2143 if (CI.isEscapingByref()) {
2144 BlockFieldFlags Flags = BLOCK_FIELD_IS_BYREF;
2145 if (T.isObjCGCWeak())
2146 Flags |= BLOCK_FIELD_IS_WEAK;
2147 return std::make_pair(BlockCaptureEntityKind::BlockObject, Flags);
2148 }
2149
2150 switch (T.isDestructedType()) {
2151 case QualType::DK_cxx_destructor:
2152 return std::make_pair(BlockCaptureEntityKind::CXXRecord, BlockFieldFlags());
2153 case QualType::DK_objc_strong_lifetime:
2154 // Use objc_storeStrong for __strong direct captures; the
2155 // dynamic tools really like it when we do this.
2156 return std::make_pair(BlockCaptureEntityKind::ARCStrong,
2157 getBlockFieldFlagsForObjCObjectPointer(CI, T));
2158 case QualType::DK_objc_weak_lifetime:
2159 // Support __weak direct captures.
2160 return std::make_pair(BlockCaptureEntityKind::ARCWeak,
2161 getBlockFieldFlagsForObjCObjectPointer(CI, T));
2162 case QualType::DK_nontrivial_c_struct:
2163 return std::make_pair(BlockCaptureEntityKind::NonTrivialCStruct,
2164 BlockFieldFlags());
2165 case QualType::DK_none: {
2166 // Non-ARC captures are strong, and we need to use _Block_object_dispose.
2167 if (T->isObjCRetainableType() && !T.getQualifiers().hasObjCLifetime() &&
2168 !LangOpts.ObjCAutoRefCount)
2169 return std::make_pair(BlockCaptureEntityKind::BlockObject,
2170 getBlockFieldFlagsForObjCObjectPointer(CI, T));
2171 // Otherwise, we have nothing to do.
2172 return std::make_pair(BlockCaptureEntityKind::None, BlockFieldFlags());
2173 }
2174 }
2175 llvm_unreachable("after exhaustive DestructionKind switch");
2176 }
2177
2178 /// Generate the destroy-helper function for a block closure object:
2179 /// static void block_destroy_helper(block_t *theBlock);
2180 ///
2181 /// Note that this destroys a heap-allocated block closure object;
2182 /// it should not be confused with a 'byref destroy helper', which
2183 /// destroys the heap-allocated contents of an individual __block
2184 /// variable.
2185 llvm::Constant *
GenerateDestroyHelperFunction(const CGBlockInfo & blockInfo)2186 CodeGenFunction::GenerateDestroyHelperFunction(const CGBlockInfo &blockInfo) {
2187 SmallVector<BlockCaptureManagedEntity, 4> DestroyedCaptures;
2188 findBlockCapturedManagedEntities(blockInfo, getLangOpts(), DestroyedCaptures);
2189 std::string FuncName =
2190 getCopyDestroyHelperFuncName(DestroyedCaptures, blockInfo.BlockAlign,
2191 CaptureStrKind::DisposeHelper, CGM);
2192
2193 if (llvm::GlobalValue *Func = CGM.getModule().getNamedValue(FuncName))
2194 return llvm::ConstantExpr::getBitCast(Func, VoidPtrTy);
2195
2196 ASTContext &C = getContext();
2197
2198 QualType ReturnTy = C.VoidTy;
2199
2200 FunctionArgList args;
2201 ImplicitParamDecl SrcDecl(C, C.VoidPtrTy, ImplicitParamDecl::Other);
2202 args.push_back(&SrcDecl);
2203
2204 const CGFunctionInfo &FI =
2205 CGM.getTypes().arrangeBuiltinFunctionDeclaration(ReturnTy, args);
2206
2207 // FIXME: We'd like to put these into a mergable by content, with
2208 // internal linkage.
2209 llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI);
2210
2211 llvm::Function *Fn =
2212 llvm::Function::Create(LTy, llvm::GlobalValue::LinkOnceODRLinkage,
2213 FuncName, &CGM.getModule());
2214 if (CGM.supportsCOMDAT())
2215 Fn->setComdat(CGM.getModule().getOrInsertComdat(FuncName));
2216
2217 IdentifierInfo *II = &C.Idents.get(FuncName);
2218
2219 SmallVector<QualType, 1> ArgTys;
2220 ArgTys.push_back(C.VoidPtrTy);
2221 QualType FunctionTy = C.getFunctionType(ReturnTy, ArgTys, {});
2222
2223 FunctionDecl *FD = FunctionDecl::Create(
2224 C, C.getTranslationUnitDecl(), SourceLocation(), SourceLocation(), II,
2225 FunctionTy, nullptr, SC_Static, false, false);
2226
2227 setBlockHelperAttributesVisibility(blockInfo.CapturesNonExternalType, Fn, FI,
2228 CGM);
2229 StartFunction(FD, ReturnTy, Fn, FI, args);
2230 markAsIgnoreThreadCheckingAtRuntime(Fn);
2231
2232 ApplyDebugLocation NL{*this, blockInfo.getBlockExpr()->getBeginLoc()};
2233
2234 llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo();
2235
2236 Address src = GetAddrOfLocalVar(&SrcDecl);
2237 src = Address(Builder.CreateLoad(src), blockInfo.BlockAlign);
2238 src = Builder.CreateBitCast(src, structPtrTy, "block");
2239
2240 CodeGenFunction::RunCleanupsScope cleanups(*this);
2241
2242 for (const auto &DestroyedCapture : DestroyedCaptures) {
2243 const BlockDecl::Capture &CI = *DestroyedCapture.CI;
2244 const CGBlockInfo::Capture &capture = *DestroyedCapture.Capture;
2245 BlockFieldFlags flags = DestroyedCapture.DisposeFlags;
2246
2247 Address srcField = Builder.CreateStructGEP(src, capture.getIndex());
2248
2249 pushCaptureCleanup(DestroyedCapture.DisposeKind, srcField,
2250 CI.getVariable()->getType(), flags,
2251 /*ForCopyHelper*/ false, CI.getVariable(), *this);
2252 }
2253
2254 cleanups.ForceCleanup();
2255
2256 FinishFunction();
2257
2258 return llvm::ConstantExpr::getBitCast(Fn, VoidPtrTy);
2259 }
2260
2261 namespace {
2262
2263 /// Emits the copy/dispose helper functions for a __block object of id type.
2264 class ObjectByrefHelpers final : public BlockByrefHelpers {
2265 BlockFieldFlags Flags;
2266
2267 public:
ObjectByrefHelpers(CharUnits alignment,BlockFieldFlags flags)2268 ObjectByrefHelpers(CharUnits alignment, BlockFieldFlags flags)
2269 : BlockByrefHelpers(alignment), Flags(flags) {}
2270
emitCopy(CodeGenFunction & CGF,Address destField,Address srcField)2271 void emitCopy(CodeGenFunction &CGF, Address destField,
2272 Address srcField) override {
2273 destField = CGF.Builder.CreateBitCast(destField, CGF.VoidPtrTy);
2274
2275 srcField = CGF.Builder.CreateBitCast(srcField, CGF.VoidPtrPtrTy);
2276 llvm::Value *srcValue = CGF.Builder.CreateLoad(srcField);
2277
2278 unsigned flags = (Flags | BLOCK_BYREF_CALLER).getBitMask();
2279
2280 llvm::Value *flagsVal = llvm::ConstantInt::get(CGF.Int32Ty, flags);
2281 llvm::FunctionCallee fn = CGF.CGM.getBlockObjectAssign();
2282
2283 llvm::Value *args[] = { destField.getPointer(), srcValue, flagsVal };
2284 CGF.EmitNounwindRuntimeCall(fn, args);
2285 }
2286
emitDispose(CodeGenFunction & CGF,Address field)2287 void emitDispose(CodeGenFunction &CGF, Address field) override {
2288 field = CGF.Builder.CreateBitCast(field, CGF.Int8PtrTy->getPointerTo(0));
2289 llvm::Value *value = CGF.Builder.CreateLoad(field);
2290
2291 CGF.BuildBlockRelease(value, Flags | BLOCK_BYREF_CALLER, false);
2292 }
2293
profileImpl(llvm::FoldingSetNodeID & id) const2294 void profileImpl(llvm::FoldingSetNodeID &id) const override {
2295 id.AddInteger(Flags.getBitMask());
2296 }
2297 };
2298
2299 /// Emits the copy/dispose helpers for an ARC __block __weak variable.
2300 class ARCWeakByrefHelpers final : public BlockByrefHelpers {
2301 public:
ARCWeakByrefHelpers(CharUnits alignment)2302 ARCWeakByrefHelpers(CharUnits alignment) : BlockByrefHelpers(alignment) {}
2303
emitCopy(CodeGenFunction & CGF,Address destField,Address srcField)2304 void emitCopy(CodeGenFunction &CGF, Address destField,
2305 Address srcField) override {
2306 CGF.EmitARCMoveWeak(destField, srcField);
2307 }
2308
emitDispose(CodeGenFunction & CGF,Address field)2309 void emitDispose(CodeGenFunction &CGF, Address field) override {
2310 CGF.EmitARCDestroyWeak(field);
2311 }
2312
profileImpl(llvm::FoldingSetNodeID & id) const2313 void profileImpl(llvm::FoldingSetNodeID &id) const override {
2314 // 0 is distinguishable from all pointers and byref flags
2315 id.AddInteger(0);
2316 }
2317 };
2318
2319 /// Emits the copy/dispose helpers for an ARC __block __strong variable
2320 /// that's not of block-pointer type.
2321 class ARCStrongByrefHelpers final : public BlockByrefHelpers {
2322 public:
ARCStrongByrefHelpers(CharUnits alignment)2323 ARCStrongByrefHelpers(CharUnits alignment) : BlockByrefHelpers(alignment) {}
2324
emitCopy(CodeGenFunction & CGF,Address destField,Address srcField)2325 void emitCopy(CodeGenFunction &CGF, Address destField,
2326 Address srcField) override {
2327 // Do a "move" by copying the value and then zeroing out the old
2328 // variable.
2329
2330 llvm::Value *value = CGF.Builder.CreateLoad(srcField);
2331
2332 llvm::Value *null =
2333 llvm::ConstantPointerNull::get(cast<llvm::PointerType>(value->getType()));
2334
2335 if (CGF.CGM.getCodeGenOpts().OptimizationLevel == 0) {
2336 CGF.Builder.CreateStore(null, destField);
2337 CGF.EmitARCStoreStrongCall(destField, value, /*ignored*/ true);
2338 CGF.EmitARCStoreStrongCall(srcField, null, /*ignored*/ true);
2339 return;
2340 }
2341 CGF.Builder.CreateStore(value, destField);
2342 CGF.Builder.CreateStore(null, srcField);
2343 }
2344
emitDispose(CodeGenFunction & CGF,Address field)2345 void emitDispose(CodeGenFunction &CGF, Address field) override {
2346 CGF.EmitARCDestroyStrong(field, ARCImpreciseLifetime);
2347 }
2348
profileImpl(llvm::FoldingSetNodeID & id) const2349 void profileImpl(llvm::FoldingSetNodeID &id) const override {
2350 // 1 is distinguishable from all pointers and byref flags
2351 id.AddInteger(1);
2352 }
2353 };
2354
2355 /// Emits the copy/dispose helpers for an ARC __block __strong
2356 /// variable that's of block-pointer type.
2357 class ARCStrongBlockByrefHelpers final : public BlockByrefHelpers {
2358 public:
ARCStrongBlockByrefHelpers(CharUnits alignment)2359 ARCStrongBlockByrefHelpers(CharUnits alignment)
2360 : BlockByrefHelpers(alignment) {}
2361
emitCopy(CodeGenFunction & CGF,Address destField,Address srcField)2362 void emitCopy(CodeGenFunction &CGF, Address destField,
2363 Address srcField) override {
2364 // Do the copy with objc_retainBlock; that's all that
2365 // _Block_object_assign would do anyway, and we'd have to pass the
2366 // right arguments to make sure it doesn't get no-op'ed.
2367 llvm::Value *oldValue = CGF.Builder.CreateLoad(srcField);
2368 llvm::Value *copy = CGF.EmitARCRetainBlock(oldValue, /*mandatory*/ true);
2369 CGF.Builder.CreateStore(copy, destField);
2370 }
2371
emitDispose(CodeGenFunction & CGF,Address field)2372 void emitDispose(CodeGenFunction &CGF, Address field) override {
2373 CGF.EmitARCDestroyStrong(field, ARCImpreciseLifetime);
2374 }
2375
profileImpl(llvm::FoldingSetNodeID & id) const2376 void profileImpl(llvm::FoldingSetNodeID &id) const override {
2377 // 2 is distinguishable from all pointers and byref flags
2378 id.AddInteger(2);
2379 }
2380 };
2381
2382 /// Emits the copy/dispose helpers for a __block variable with a
2383 /// nontrivial copy constructor or destructor.
2384 class CXXByrefHelpers final : public BlockByrefHelpers {
2385 QualType VarType;
2386 const Expr *CopyExpr;
2387
2388 public:
CXXByrefHelpers(CharUnits alignment,QualType type,const Expr * copyExpr)2389 CXXByrefHelpers(CharUnits alignment, QualType type,
2390 const Expr *copyExpr)
2391 : BlockByrefHelpers(alignment), VarType(type), CopyExpr(copyExpr) {}
2392
needsCopy() const2393 bool needsCopy() const override { return CopyExpr != nullptr; }
emitCopy(CodeGenFunction & CGF,Address destField,Address srcField)2394 void emitCopy(CodeGenFunction &CGF, Address destField,
2395 Address srcField) override {
2396 if (!CopyExpr) return;
2397 CGF.EmitSynthesizedCXXCopyCtor(destField, srcField, CopyExpr);
2398 }
2399
emitDispose(CodeGenFunction & CGF,Address field)2400 void emitDispose(CodeGenFunction &CGF, Address field) override {
2401 EHScopeStack::stable_iterator cleanupDepth = CGF.EHStack.stable_begin();
2402 CGF.PushDestructorCleanup(VarType, field);
2403 CGF.PopCleanupBlocks(cleanupDepth);
2404 }
2405
profileImpl(llvm::FoldingSetNodeID & id) const2406 void profileImpl(llvm::FoldingSetNodeID &id) const override {
2407 id.AddPointer(VarType.getCanonicalType().getAsOpaquePtr());
2408 }
2409 };
2410
2411 /// Emits the copy/dispose helpers for a __block variable that is a non-trivial
2412 /// C struct.
2413 class NonTrivialCStructByrefHelpers final : public BlockByrefHelpers {
2414 QualType VarType;
2415
2416 public:
NonTrivialCStructByrefHelpers(CharUnits alignment,QualType type)2417 NonTrivialCStructByrefHelpers(CharUnits alignment, QualType type)
2418 : BlockByrefHelpers(alignment), VarType(type) {}
2419
emitCopy(CodeGenFunction & CGF,Address destField,Address srcField)2420 void emitCopy(CodeGenFunction &CGF, Address destField,
2421 Address srcField) override {
2422 CGF.callCStructMoveConstructor(CGF.MakeAddrLValue(destField, VarType),
2423 CGF.MakeAddrLValue(srcField, VarType));
2424 }
2425
needsDispose() const2426 bool needsDispose() const override {
2427 return VarType.isDestructedType();
2428 }
2429
emitDispose(CodeGenFunction & CGF,Address field)2430 void emitDispose(CodeGenFunction &CGF, Address field) override {
2431 EHScopeStack::stable_iterator cleanupDepth = CGF.EHStack.stable_begin();
2432 CGF.pushDestroy(VarType.isDestructedType(), field, VarType);
2433 CGF.PopCleanupBlocks(cleanupDepth);
2434 }
2435
profileImpl(llvm::FoldingSetNodeID & id) const2436 void profileImpl(llvm::FoldingSetNodeID &id) const override {
2437 id.AddPointer(VarType.getCanonicalType().getAsOpaquePtr());
2438 }
2439 };
2440 } // end anonymous namespace
2441
2442 static llvm::Constant *
generateByrefCopyHelper(CodeGenFunction & CGF,const BlockByrefInfo & byrefInfo,BlockByrefHelpers & generator)2443 generateByrefCopyHelper(CodeGenFunction &CGF, const BlockByrefInfo &byrefInfo,
2444 BlockByrefHelpers &generator) {
2445 ASTContext &Context = CGF.getContext();
2446
2447 QualType ReturnTy = Context.VoidTy;
2448
2449 FunctionArgList args;
2450 ImplicitParamDecl Dst(Context, Context.VoidPtrTy, ImplicitParamDecl::Other);
2451 args.push_back(&Dst);
2452
2453 ImplicitParamDecl Src(Context, Context.VoidPtrTy, ImplicitParamDecl::Other);
2454 args.push_back(&Src);
2455
2456 const CGFunctionInfo &FI =
2457 CGF.CGM.getTypes().arrangeBuiltinFunctionDeclaration(ReturnTy, args);
2458
2459 llvm::FunctionType *LTy = CGF.CGM.getTypes().GetFunctionType(FI);
2460
2461 // FIXME: We'd like to put these into a mergable by content, with
2462 // internal linkage.
2463 llvm::Function *Fn =
2464 llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
2465 "__Block_byref_object_copy_", &CGF.CGM.getModule());
2466
2467 IdentifierInfo *II
2468 = &Context.Idents.get("__Block_byref_object_copy_");
2469
2470 SmallVector<QualType, 2> ArgTys;
2471 ArgTys.push_back(Context.VoidPtrTy);
2472 ArgTys.push_back(Context.VoidPtrTy);
2473 QualType FunctionTy = Context.getFunctionType(ReturnTy, ArgTys, {});
2474
2475 FunctionDecl *FD = FunctionDecl::Create(
2476 Context, Context.getTranslationUnitDecl(), SourceLocation(),
2477 SourceLocation(), II, FunctionTy, nullptr, SC_Static, false, false);
2478
2479 CGF.CGM.SetInternalFunctionAttributes(GlobalDecl(), Fn, FI);
2480
2481 CGF.StartFunction(FD, ReturnTy, Fn, FI, args);
2482
2483 if (generator.needsCopy()) {
2484 llvm::Type *byrefPtrType = byrefInfo.Type->getPointerTo(0);
2485
2486 // dst->x
2487 Address destField = CGF.GetAddrOfLocalVar(&Dst);
2488 destField = Address(CGF.Builder.CreateLoad(destField),
2489 byrefInfo.ByrefAlignment);
2490 destField = CGF.Builder.CreateBitCast(destField, byrefPtrType);
2491 destField = CGF.emitBlockByrefAddress(destField, byrefInfo, false,
2492 "dest-object");
2493
2494 // src->x
2495 Address srcField = CGF.GetAddrOfLocalVar(&Src);
2496 srcField = Address(CGF.Builder.CreateLoad(srcField),
2497 byrefInfo.ByrefAlignment);
2498 srcField = CGF.Builder.CreateBitCast(srcField, byrefPtrType);
2499 srcField = CGF.emitBlockByrefAddress(srcField, byrefInfo, false,
2500 "src-object");
2501
2502 generator.emitCopy(CGF, destField, srcField);
2503 }
2504
2505 CGF.FinishFunction();
2506
2507 return llvm::ConstantExpr::getBitCast(Fn, CGF.Int8PtrTy);
2508 }
2509
2510 /// Build the copy helper for a __block variable.
buildByrefCopyHelper(CodeGenModule & CGM,const BlockByrefInfo & byrefInfo,BlockByrefHelpers & generator)2511 static llvm::Constant *buildByrefCopyHelper(CodeGenModule &CGM,
2512 const BlockByrefInfo &byrefInfo,
2513 BlockByrefHelpers &generator) {
2514 CodeGenFunction CGF(CGM);
2515 return generateByrefCopyHelper(CGF, byrefInfo, generator);
2516 }
2517
2518 /// Generate code for a __block variable's dispose helper.
2519 static llvm::Constant *
generateByrefDisposeHelper(CodeGenFunction & CGF,const BlockByrefInfo & byrefInfo,BlockByrefHelpers & generator)2520 generateByrefDisposeHelper(CodeGenFunction &CGF,
2521 const BlockByrefInfo &byrefInfo,
2522 BlockByrefHelpers &generator) {
2523 ASTContext &Context = CGF.getContext();
2524 QualType R = Context.VoidTy;
2525
2526 FunctionArgList args;
2527 ImplicitParamDecl Src(CGF.getContext(), Context.VoidPtrTy,
2528 ImplicitParamDecl::Other);
2529 args.push_back(&Src);
2530
2531 const CGFunctionInfo &FI =
2532 CGF.CGM.getTypes().arrangeBuiltinFunctionDeclaration(R, args);
2533
2534 llvm::FunctionType *LTy = CGF.CGM.getTypes().GetFunctionType(FI);
2535
2536 // FIXME: We'd like to put these into a mergable by content, with
2537 // internal linkage.
2538 llvm::Function *Fn =
2539 llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
2540 "__Block_byref_object_dispose_",
2541 &CGF.CGM.getModule());
2542
2543 IdentifierInfo *II
2544 = &Context.Idents.get("__Block_byref_object_dispose_");
2545
2546 SmallVector<QualType, 1> ArgTys;
2547 ArgTys.push_back(Context.VoidPtrTy);
2548 QualType FunctionTy = Context.getFunctionType(R, ArgTys, {});
2549
2550 FunctionDecl *FD = FunctionDecl::Create(
2551 Context, Context.getTranslationUnitDecl(), SourceLocation(),
2552 SourceLocation(), II, FunctionTy, nullptr, SC_Static, false, false);
2553
2554 CGF.CGM.SetInternalFunctionAttributes(GlobalDecl(), Fn, FI);
2555
2556 CGF.StartFunction(FD, R, Fn, FI, args);
2557
2558 if (generator.needsDispose()) {
2559 Address addr = CGF.GetAddrOfLocalVar(&Src);
2560 addr = Address(CGF.Builder.CreateLoad(addr), byrefInfo.ByrefAlignment);
2561 auto byrefPtrType = byrefInfo.Type->getPointerTo(0);
2562 addr = CGF.Builder.CreateBitCast(addr, byrefPtrType);
2563 addr = CGF.emitBlockByrefAddress(addr, byrefInfo, false, "object");
2564
2565 generator.emitDispose(CGF, addr);
2566 }
2567
2568 CGF.FinishFunction();
2569
2570 return llvm::ConstantExpr::getBitCast(Fn, CGF.Int8PtrTy);
2571 }
2572
2573 /// Build the dispose helper for a __block variable.
buildByrefDisposeHelper(CodeGenModule & CGM,const BlockByrefInfo & byrefInfo,BlockByrefHelpers & generator)2574 static llvm::Constant *buildByrefDisposeHelper(CodeGenModule &CGM,
2575 const BlockByrefInfo &byrefInfo,
2576 BlockByrefHelpers &generator) {
2577 CodeGenFunction CGF(CGM);
2578 return generateByrefDisposeHelper(CGF, byrefInfo, generator);
2579 }
2580
2581 /// Lazily build the copy and dispose helpers for a __block variable
2582 /// with the given information.
2583 template <class T>
buildByrefHelpers(CodeGenModule & CGM,const BlockByrefInfo & byrefInfo,T && generator)2584 static T *buildByrefHelpers(CodeGenModule &CGM, const BlockByrefInfo &byrefInfo,
2585 T &&generator) {
2586 llvm::FoldingSetNodeID id;
2587 generator.Profile(id);
2588
2589 void *insertPos;
2590 BlockByrefHelpers *node
2591 = CGM.ByrefHelpersCache.FindNodeOrInsertPos(id, insertPos);
2592 if (node) return static_cast<T*>(node);
2593
2594 generator.CopyHelper = buildByrefCopyHelper(CGM, byrefInfo, generator);
2595 generator.DisposeHelper = buildByrefDisposeHelper(CGM, byrefInfo, generator);
2596
2597 T *copy = new (CGM.getContext()) T(std::forward<T>(generator));
2598 CGM.ByrefHelpersCache.InsertNode(copy, insertPos);
2599 return copy;
2600 }
2601
2602 /// Build the copy and dispose helpers for the given __block variable
2603 /// emission. Places the helpers in the global cache. Returns null
2604 /// if no helpers are required.
2605 BlockByrefHelpers *
buildByrefHelpers(llvm::StructType & byrefType,const AutoVarEmission & emission)2606 CodeGenFunction::buildByrefHelpers(llvm::StructType &byrefType,
2607 const AutoVarEmission &emission) {
2608 const VarDecl &var = *emission.Variable;
2609 assert(var.isEscapingByref() &&
2610 "only escaping __block variables need byref helpers");
2611
2612 QualType type = var.getType();
2613
2614 auto &byrefInfo = getBlockByrefInfo(&var);
2615
2616 // The alignment we care about for the purposes of uniquing byref
2617 // helpers is the alignment of the actual byref value field.
2618 CharUnits valueAlignment =
2619 byrefInfo.ByrefAlignment.alignmentAtOffset(byrefInfo.FieldOffset);
2620
2621 if (const CXXRecordDecl *record = type->getAsCXXRecordDecl()) {
2622 const Expr *copyExpr =
2623 CGM.getContext().getBlockVarCopyInit(&var).getCopyExpr();
2624 if (!copyExpr && record->hasTrivialDestructor()) return nullptr;
2625
2626 return ::buildByrefHelpers(
2627 CGM, byrefInfo, CXXByrefHelpers(valueAlignment, type, copyExpr));
2628 }
2629
2630 // If type is a non-trivial C struct type that is non-trivial to
2631 // destructly move or destroy, build the copy and dispose helpers.
2632 if (type.isNonTrivialToPrimitiveDestructiveMove() == QualType::PCK_Struct ||
2633 type.isDestructedType() == QualType::DK_nontrivial_c_struct)
2634 return ::buildByrefHelpers(
2635 CGM, byrefInfo, NonTrivialCStructByrefHelpers(valueAlignment, type));
2636
2637 // Otherwise, if we don't have a retainable type, there's nothing to do.
2638 // that the runtime does extra copies.
2639 if (!type->isObjCRetainableType()) return nullptr;
2640
2641 Qualifiers qs = type.getQualifiers();
2642
2643 // If we have lifetime, that dominates.
2644 if (Qualifiers::ObjCLifetime lifetime = qs.getObjCLifetime()) {
2645 switch (lifetime) {
2646 case Qualifiers::OCL_None: llvm_unreachable("impossible");
2647
2648 // These are just bits as far as the runtime is concerned.
2649 case Qualifiers::OCL_ExplicitNone:
2650 case Qualifiers::OCL_Autoreleasing:
2651 return nullptr;
2652
2653 // Tell the runtime that this is ARC __weak, called by the
2654 // byref routines.
2655 case Qualifiers::OCL_Weak:
2656 return ::buildByrefHelpers(CGM, byrefInfo,
2657 ARCWeakByrefHelpers(valueAlignment));
2658
2659 // ARC __strong __block variables need to be retained.
2660 case Qualifiers::OCL_Strong:
2661 // Block pointers need to be copied, and there's no direct
2662 // transfer possible.
2663 if (type->isBlockPointerType()) {
2664 return ::buildByrefHelpers(CGM, byrefInfo,
2665 ARCStrongBlockByrefHelpers(valueAlignment));
2666
2667 // Otherwise, we transfer ownership of the retain from the stack
2668 // to the heap.
2669 } else {
2670 return ::buildByrefHelpers(CGM, byrefInfo,
2671 ARCStrongByrefHelpers(valueAlignment));
2672 }
2673 }
2674 llvm_unreachable("fell out of lifetime switch!");
2675 }
2676
2677 BlockFieldFlags flags;
2678 if (type->isBlockPointerType()) {
2679 flags |= BLOCK_FIELD_IS_BLOCK;
2680 } else if (CGM.getContext().isObjCNSObjectType(type) ||
2681 type->isObjCObjectPointerType()) {
2682 flags |= BLOCK_FIELD_IS_OBJECT;
2683 } else {
2684 return nullptr;
2685 }
2686
2687 if (type.isObjCGCWeak())
2688 flags |= BLOCK_FIELD_IS_WEAK;
2689
2690 return ::buildByrefHelpers(CGM, byrefInfo,
2691 ObjectByrefHelpers(valueAlignment, flags));
2692 }
2693
emitBlockByrefAddress(Address baseAddr,const VarDecl * var,bool followForward)2694 Address CodeGenFunction::emitBlockByrefAddress(Address baseAddr,
2695 const VarDecl *var,
2696 bool followForward) {
2697 auto &info = getBlockByrefInfo(var);
2698 return emitBlockByrefAddress(baseAddr, info, followForward, var->getName());
2699 }
2700
emitBlockByrefAddress(Address baseAddr,const BlockByrefInfo & info,bool followForward,const llvm::Twine & name)2701 Address CodeGenFunction::emitBlockByrefAddress(Address baseAddr,
2702 const BlockByrefInfo &info,
2703 bool followForward,
2704 const llvm::Twine &name) {
2705 // Chase the forwarding address if requested.
2706 if (followForward) {
2707 Address forwardingAddr = Builder.CreateStructGEP(baseAddr, 1, "forwarding");
2708 baseAddr = Address(Builder.CreateLoad(forwardingAddr), info.ByrefAlignment);
2709 }
2710
2711 return Builder.CreateStructGEP(baseAddr, info.FieldIndex, name);
2712 }
2713
2714 /// BuildByrefInfo - This routine changes a __block variable declared as T x
2715 /// into:
2716 ///
2717 /// struct {
2718 /// void *__isa;
2719 /// void *__forwarding;
2720 /// int32_t __flags;
2721 /// int32_t __size;
2722 /// void *__copy_helper; // only if needed
2723 /// void *__destroy_helper; // only if needed
2724 /// void *__byref_variable_layout;// only if needed
2725 /// char padding[X]; // only if needed
2726 /// T x;
2727 /// } x
2728 ///
getBlockByrefInfo(const VarDecl * D)2729 const BlockByrefInfo &CodeGenFunction::getBlockByrefInfo(const VarDecl *D) {
2730 auto it = BlockByrefInfos.find(D);
2731 if (it != BlockByrefInfos.end())
2732 return it->second;
2733
2734 llvm::StructType *byrefType =
2735 llvm::StructType::create(getLLVMContext(),
2736 "struct.__block_byref_" + D->getNameAsString());
2737
2738 QualType Ty = D->getType();
2739
2740 CharUnits size;
2741 SmallVector<llvm::Type *, 8> types;
2742
2743 // void *__isa;
2744 types.push_back(Int8PtrTy);
2745 size += getPointerSize();
2746
2747 // void *__forwarding;
2748 types.push_back(llvm::PointerType::getUnqual(byrefType));
2749 size += getPointerSize();
2750
2751 // int32_t __flags;
2752 types.push_back(Int32Ty);
2753 size += CharUnits::fromQuantity(4);
2754
2755 // int32_t __size;
2756 types.push_back(Int32Ty);
2757 size += CharUnits::fromQuantity(4);
2758
2759 // Note that this must match *exactly* the logic in buildByrefHelpers.
2760 bool hasCopyAndDispose = getContext().BlockRequiresCopying(Ty, D);
2761 if (hasCopyAndDispose) {
2762 /// void *__copy_helper;
2763 types.push_back(Int8PtrTy);
2764 size += getPointerSize();
2765
2766 /// void *__destroy_helper;
2767 types.push_back(Int8PtrTy);
2768 size += getPointerSize();
2769 }
2770
2771 bool HasByrefExtendedLayout = false;
2772 Qualifiers::ObjCLifetime Lifetime;
2773 if (getContext().getByrefLifetime(Ty, Lifetime, HasByrefExtendedLayout) &&
2774 HasByrefExtendedLayout) {
2775 /// void *__byref_variable_layout;
2776 types.push_back(Int8PtrTy);
2777 size += CharUnits::fromQuantity(PointerSizeInBytes);
2778 }
2779
2780 // T x;
2781 llvm::Type *varTy = ConvertTypeForMem(Ty);
2782
2783 bool packed = false;
2784 CharUnits varAlign = getContext().getDeclAlign(D);
2785 CharUnits varOffset = size.alignTo(varAlign);
2786
2787 // We may have to insert padding.
2788 if (varOffset != size) {
2789 llvm::Type *paddingTy =
2790 llvm::ArrayType::get(Int8Ty, (varOffset - size).getQuantity());
2791
2792 types.push_back(paddingTy);
2793 size = varOffset;
2794
2795 // Conversely, we might have to prevent LLVM from inserting padding.
2796 } else if (CGM.getDataLayout().getABITypeAlignment(varTy)
2797 > varAlign.getQuantity()) {
2798 packed = true;
2799 }
2800 types.push_back(varTy);
2801
2802 byrefType->setBody(types, packed);
2803
2804 BlockByrefInfo info;
2805 info.Type = byrefType;
2806 info.FieldIndex = types.size() - 1;
2807 info.FieldOffset = varOffset;
2808 info.ByrefAlignment = std::max(varAlign, getPointerAlign());
2809
2810 auto pair = BlockByrefInfos.insert({D, info});
2811 assert(pair.second && "info was inserted recursively?");
2812 return pair.first->second;
2813 }
2814
2815 /// Initialize the structural components of a __block variable, i.e.
2816 /// everything but the actual object.
emitByrefStructureInit(const AutoVarEmission & emission)2817 void CodeGenFunction::emitByrefStructureInit(const AutoVarEmission &emission) {
2818 // Find the address of the local.
2819 Address addr = emission.Addr;
2820
2821 // That's an alloca of the byref structure type.
2822 llvm::StructType *byrefType = cast<llvm::StructType>(
2823 cast<llvm::PointerType>(addr.getPointer()->getType())->getElementType());
2824
2825 unsigned nextHeaderIndex = 0;
2826 CharUnits nextHeaderOffset;
2827 auto storeHeaderField = [&](llvm::Value *value, CharUnits fieldSize,
2828 const Twine &name) {
2829 auto fieldAddr = Builder.CreateStructGEP(addr, nextHeaderIndex, name);
2830 Builder.CreateStore(value, fieldAddr);
2831
2832 nextHeaderIndex++;
2833 nextHeaderOffset += fieldSize;
2834 };
2835
2836 // Build the byref helpers if necessary. This is null if we don't need any.
2837 BlockByrefHelpers *helpers = buildByrefHelpers(*byrefType, emission);
2838
2839 const VarDecl &D = *emission.Variable;
2840 QualType type = D.getType();
2841
2842 bool HasByrefExtendedLayout;
2843 Qualifiers::ObjCLifetime ByrefLifetime;
2844 bool ByRefHasLifetime =
2845 getContext().getByrefLifetime(type, ByrefLifetime, HasByrefExtendedLayout);
2846
2847 llvm::Value *V;
2848
2849 // Initialize the 'isa', which is just 0 or 1.
2850 int isa = 0;
2851 if (type.isObjCGCWeak())
2852 isa = 1;
2853 V = Builder.CreateIntToPtr(Builder.getInt32(isa), Int8PtrTy, "isa");
2854 storeHeaderField(V, getPointerSize(), "byref.isa");
2855
2856 // Store the address of the variable into its own forwarding pointer.
2857 storeHeaderField(addr.getPointer(), getPointerSize(), "byref.forwarding");
2858
2859 // Blocks ABI:
2860 // c) the flags field is set to either 0 if no helper functions are
2861 // needed or BLOCK_BYREF_HAS_COPY_DISPOSE if they are,
2862 BlockFlags flags;
2863 if (helpers) flags |= BLOCK_BYREF_HAS_COPY_DISPOSE;
2864 if (ByRefHasLifetime) {
2865 if (HasByrefExtendedLayout) flags |= BLOCK_BYREF_LAYOUT_EXTENDED;
2866 else switch (ByrefLifetime) {
2867 case Qualifiers::OCL_Strong:
2868 flags |= BLOCK_BYREF_LAYOUT_STRONG;
2869 break;
2870 case Qualifiers::OCL_Weak:
2871 flags |= BLOCK_BYREF_LAYOUT_WEAK;
2872 break;
2873 case Qualifiers::OCL_ExplicitNone:
2874 flags |= BLOCK_BYREF_LAYOUT_UNRETAINED;
2875 break;
2876 case Qualifiers::OCL_None:
2877 if (!type->isObjCObjectPointerType() && !type->isBlockPointerType())
2878 flags |= BLOCK_BYREF_LAYOUT_NON_OBJECT;
2879 break;
2880 default:
2881 break;
2882 }
2883 if (CGM.getLangOpts().ObjCGCBitmapPrint) {
2884 printf("\n Inline flag for BYREF variable layout (%d):", flags.getBitMask());
2885 if (flags & BLOCK_BYREF_HAS_COPY_DISPOSE)
2886 printf(" BLOCK_BYREF_HAS_COPY_DISPOSE");
2887 if (flags & BLOCK_BYREF_LAYOUT_MASK) {
2888 BlockFlags ThisFlag(flags.getBitMask() & BLOCK_BYREF_LAYOUT_MASK);
2889 if (ThisFlag == BLOCK_BYREF_LAYOUT_EXTENDED)
2890 printf(" BLOCK_BYREF_LAYOUT_EXTENDED");
2891 if (ThisFlag == BLOCK_BYREF_LAYOUT_STRONG)
2892 printf(" BLOCK_BYREF_LAYOUT_STRONG");
2893 if (ThisFlag == BLOCK_BYREF_LAYOUT_WEAK)
2894 printf(" BLOCK_BYREF_LAYOUT_WEAK");
2895 if (ThisFlag == BLOCK_BYREF_LAYOUT_UNRETAINED)
2896 printf(" BLOCK_BYREF_LAYOUT_UNRETAINED");
2897 if (ThisFlag == BLOCK_BYREF_LAYOUT_NON_OBJECT)
2898 printf(" BLOCK_BYREF_LAYOUT_NON_OBJECT");
2899 }
2900 printf("\n");
2901 }
2902 }
2903 storeHeaderField(llvm::ConstantInt::get(IntTy, flags.getBitMask()),
2904 getIntSize(), "byref.flags");
2905
2906 CharUnits byrefSize = CGM.GetTargetTypeStoreSize(byrefType);
2907 V = llvm::ConstantInt::get(IntTy, byrefSize.getQuantity());
2908 storeHeaderField(V, getIntSize(), "byref.size");
2909
2910 if (helpers) {
2911 storeHeaderField(helpers->CopyHelper, getPointerSize(),
2912 "byref.copyHelper");
2913 storeHeaderField(helpers->DisposeHelper, getPointerSize(),
2914 "byref.disposeHelper");
2915 }
2916
2917 if (ByRefHasLifetime && HasByrefExtendedLayout) {
2918 auto layoutInfo = CGM.getObjCRuntime().BuildByrefLayout(CGM, type);
2919 storeHeaderField(layoutInfo, getPointerSize(), "byref.layout");
2920 }
2921 }
2922
BuildBlockRelease(llvm::Value * V,BlockFieldFlags flags,bool CanThrow)2923 void CodeGenFunction::BuildBlockRelease(llvm::Value *V, BlockFieldFlags flags,
2924 bool CanThrow) {
2925 llvm::FunctionCallee F = CGM.getBlockObjectDispose();
2926 llvm::Value *args[] = {
2927 Builder.CreateBitCast(V, Int8PtrTy),
2928 llvm::ConstantInt::get(Int32Ty, flags.getBitMask())
2929 };
2930
2931 if (CanThrow)
2932 EmitRuntimeCallOrInvoke(F, args);
2933 else
2934 EmitNounwindRuntimeCall(F, args);
2935 }
2936
enterByrefCleanup(CleanupKind Kind,Address Addr,BlockFieldFlags Flags,bool LoadBlockVarAddr,bool CanThrow)2937 void CodeGenFunction::enterByrefCleanup(CleanupKind Kind, Address Addr,
2938 BlockFieldFlags Flags,
2939 bool LoadBlockVarAddr, bool CanThrow) {
2940 EHStack.pushCleanup<CallBlockRelease>(Kind, Addr, Flags, LoadBlockVarAddr,
2941 CanThrow);
2942 }
2943
2944 /// Adjust the declaration of something from the blocks API.
configureBlocksRuntimeObject(CodeGenModule & CGM,llvm::Constant * C)2945 static void configureBlocksRuntimeObject(CodeGenModule &CGM,
2946 llvm::Constant *C) {
2947 auto *GV = cast<llvm::GlobalValue>(C->stripPointerCasts());
2948
2949 if (CGM.getTarget().getTriple().isOSBinFormatCOFF()) {
2950 IdentifierInfo &II = CGM.getContext().Idents.get(C->getName());
2951 TranslationUnitDecl *TUDecl = CGM.getContext().getTranslationUnitDecl();
2952 DeclContext *DC = TranslationUnitDecl::castToDeclContext(TUDecl);
2953
2954 assert((isa<llvm::Function>(C->stripPointerCasts()) ||
2955 isa<llvm::GlobalVariable>(C->stripPointerCasts())) &&
2956 "expected Function or GlobalVariable");
2957
2958 const NamedDecl *ND = nullptr;
2959 for (const auto &Result : DC->lookup(&II))
2960 if ((ND = dyn_cast<FunctionDecl>(Result)) ||
2961 (ND = dyn_cast<VarDecl>(Result)))
2962 break;
2963
2964 // TODO: support static blocks runtime
2965 if (GV->isDeclaration() && (!ND || !ND->hasAttr<DLLExportAttr>())) {
2966 GV->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass);
2967 GV->setLinkage(llvm::GlobalValue::ExternalLinkage);
2968 } else {
2969 GV->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);
2970 GV->setLinkage(llvm::GlobalValue::ExternalLinkage);
2971 }
2972 }
2973
2974 if (CGM.getLangOpts().BlocksRuntimeOptional && GV->isDeclaration() &&
2975 GV->hasExternalLinkage())
2976 GV->setLinkage(llvm::GlobalValue::ExternalWeakLinkage);
2977
2978 CGM.setDSOLocal(GV);
2979 }
2980
getBlockObjectDispose()2981 llvm::FunctionCallee CodeGenModule::getBlockObjectDispose() {
2982 if (BlockObjectDispose)
2983 return BlockObjectDispose;
2984
2985 llvm::Type *args[] = { Int8PtrTy, Int32Ty };
2986 llvm::FunctionType *fty
2987 = llvm::FunctionType::get(VoidTy, args, false);
2988 BlockObjectDispose = CreateRuntimeFunction(fty, "_Block_object_dispose");
2989 configureBlocksRuntimeObject(
2990 *this, cast<llvm::Constant>(BlockObjectDispose.getCallee()));
2991 return BlockObjectDispose;
2992 }
2993
getBlockObjectAssign()2994 llvm::FunctionCallee CodeGenModule::getBlockObjectAssign() {
2995 if (BlockObjectAssign)
2996 return BlockObjectAssign;
2997
2998 llvm::Type *args[] = { Int8PtrTy, Int8PtrTy, Int32Ty };
2999 llvm::FunctionType *fty
3000 = llvm::FunctionType::get(VoidTy, args, false);
3001 BlockObjectAssign = CreateRuntimeFunction(fty, "_Block_object_assign");
3002 configureBlocksRuntimeObject(
3003 *this, cast<llvm::Constant>(BlockObjectAssign.getCallee()));
3004 return BlockObjectAssign;
3005 }
3006
getNSConcreteGlobalBlock()3007 llvm::Constant *CodeGenModule::getNSConcreteGlobalBlock() {
3008 if (NSConcreteGlobalBlock)
3009 return NSConcreteGlobalBlock;
3010
3011 NSConcreteGlobalBlock = GetOrCreateLLVMGlobal("_NSConcreteGlobalBlock",
3012 Int8PtrTy->getPointerTo(),
3013 nullptr);
3014 configureBlocksRuntimeObject(*this, NSConcreteGlobalBlock);
3015 return NSConcreteGlobalBlock;
3016 }
3017
getNSConcreteStackBlock()3018 llvm::Constant *CodeGenModule::getNSConcreteStackBlock() {
3019 if (NSConcreteStackBlock)
3020 return NSConcreteStackBlock;
3021
3022 NSConcreteStackBlock = GetOrCreateLLVMGlobal("_NSConcreteStackBlock",
3023 Int8PtrTy->getPointerTo(),
3024 nullptr);
3025 configureBlocksRuntimeObject(*this, NSConcreteStackBlock);
3026 return NSConcreteStackBlock;
3027 }
3028