1//===--- CodeGenTypes.cpp - Type translation for LLVM CodeGen -------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This is the code that handles AST -> LLVM type lowering.
11//
12//===----------------------------------------------------------------------===//
13
14#include "CodeGenTypes.h"
15#include "CGCXXABI.h"
16#include "CGCall.h"
17#include "CGOpenCLRuntime.h"
18#include "CGRecordLayout.h"
19#include "TargetInfo.h"
20#include "clang/AST/ASTContext.h"
21#include "clang/AST/DeclCXX.h"
22#include "clang/AST/DeclObjC.h"
23#include "clang/AST/Expr.h"
24#include "clang/AST/RecordLayout.h"
25#include "clang/CodeGen/CGFunctionInfo.h"
26#include "llvm/IR/DataLayout.h"
27#include "llvm/IR/DerivedTypes.h"
28#include "llvm/IR/Module.h"
29using namespace clang;
30using namespace CodeGen;
31
32CodeGenTypes::CodeGenTypes(CodeGenModule &cgm)
33  : CGM(cgm), Context(cgm.getContext()), TheModule(cgm.getModule()),
34    Target(cgm.getTarget()), TheCXXABI(cgm.getCXXABI()),
35    TheABIInfo(cgm.getTargetCodeGenInfo().getABIInfo()) {
36  SkippedLayout = false;
37}
38
39CodeGenTypes::~CodeGenTypes() {
40  llvm::DeleteContainerSeconds(CGRecordLayouts);
41
42  for (llvm::FoldingSet<CGFunctionInfo>::iterator
43       I = FunctionInfos.begin(), E = FunctionInfos.end(); I != E; )
44    delete &*I++;
45}
46
47void CodeGenTypes::addRecordTypeName(const RecordDecl *RD,
48                                     llvm::StructType *Ty,
49                                     StringRef suffix) {
50  SmallString<256> TypeName;
51  llvm::raw_svector_ostream OS(TypeName);
52  OS << RD->getKindName() << '.';
53
54  // Name the codegen type after the typedef name
55  // if there is no tag type name available
56  if (RD->getIdentifier()) {
57    // FIXME: We should not have to check for a null decl context here.
58    // Right now we do it because the implicit Obj-C decls don't have one.
59    if (RD->getDeclContext())
60      RD->printQualifiedName(OS);
61    else
62      RD->printName(OS);
63  } else if (const TypedefNameDecl *TDD = RD->getTypedefNameForAnonDecl()) {
64    // FIXME: We should not have to check for a null decl context here.
65    // Right now we do it because the implicit Obj-C decls don't have one.
66    if (TDD->getDeclContext())
67      TDD->printQualifiedName(OS);
68    else
69      TDD->printName(OS);
70  } else
71    OS << "anon";
72
73  if (!suffix.empty())
74    OS << suffix;
75
76  Ty->setName(OS.str());
77}
78
79/// ConvertTypeForMem - Convert type T into a llvm::Type.  This differs from
80/// ConvertType in that it is used to convert to the memory representation for
81/// a type.  For example, the scalar representation for _Bool is i1, but the
82/// memory representation is usually i8 or i32, depending on the target.
83llvm::Type *CodeGenTypes::ConvertTypeForMem(QualType T) {
84  llvm::Type *R = ConvertType(T);
85
86  // If this is a non-bool type, don't map it.
87  if (!R->isIntegerTy(1))
88    return R;
89
90  // Otherwise, return an integer of the target-specified size.
91  return llvm::IntegerType::get(getLLVMContext(),
92                                (unsigned)Context.getTypeSize(T));
93}
94
95
96/// isRecordLayoutComplete - Return true if the specified type is already
97/// completely laid out.
98bool CodeGenTypes::isRecordLayoutComplete(const Type *Ty) const {
99  llvm::DenseMap<const Type*, llvm::StructType *>::const_iterator I =
100  RecordDeclTypes.find(Ty);
101  return I != RecordDeclTypes.end() && !I->second->isOpaque();
102}
103
104static bool
105isSafeToConvert(QualType T, CodeGenTypes &CGT,
106                llvm::SmallPtrSet<const RecordDecl*, 16> &AlreadyChecked);
107
108
109/// isSafeToConvert - Return true if it is safe to convert the specified record
110/// decl to IR and lay it out, false if doing so would cause us to get into a
111/// recursive compilation mess.
112static bool
113isSafeToConvert(const RecordDecl *RD, CodeGenTypes &CGT,
114                llvm::SmallPtrSet<const RecordDecl*, 16> &AlreadyChecked) {
115  // If we have already checked this type (maybe the same type is used by-value
116  // multiple times in multiple structure fields, don't check again.
117  if (!AlreadyChecked.insert(RD).second)
118    return true;
119
120  const Type *Key = CGT.getContext().getTagDeclType(RD).getTypePtr();
121
122  // If this type is already laid out, converting it is a noop.
123  if (CGT.isRecordLayoutComplete(Key)) return true;
124
125  // If this type is currently being laid out, we can't recursively compile it.
126  if (CGT.isRecordBeingLaidOut(Key))
127    return false;
128
129  // If this type would require laying out bases that are currently being laid
130  // out, don't do it.  This includes virtual base classes which get laid out
131  // when a class is translated, even though they aren't embedded by-value into
132  // the class.
133  if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD)) {
134    for (const auto &I : CRD->bases())
135      if (!isSafeToConvert(I.getType()->getAs<RecordType>()->getDecl(),
136                           CGT, AlreadyChecked))
137        return false;
138  }
139
140  // If this type would require laying out members that are currently being laid
141  // out, don't do it.
142  for (const auto *I : RD->fields())
143    if (!isSafeToConvert(I->getType(), CGT, AlreadyChecked))
144      return false;
145
146  // If there are no problems, lets do it.
147  return true;
148}
149
150/// isSafeToConvert - Return true if it is safe to convert this field type,
151/// which requires the structure elements contained by-value to all be
152/// recursively safe to convert.
153static bool
154isSafeToConvert(QualType T, CodeGenTypes &CGT,
155                llvm::SmallPtrSet<const RecordDecl*, 16> &AlreadyChecked) {
156  // Strip off atomic type sugar.
157  if (const auto *AT = T->getAs<AtomicType>())
158    T = AT->getValueType();
159
160  // If this is a record, check it.
161  if (const auto *RT = T->getAs<RecordType>())
162    return isSafeToConvert(RT->getDecl(), CGT, AlreadyChecked);
163
164  // If this is an array, check the elements, which are embedded inline.
165  if (const auto *AT = CGT.getContext().getAsArrayType(T))
166    return isSafeToConvert(AT->getElementType(), CGT, AlreadyChecked);
167
168  // Otherwise, there is no concern about transforming this.  We only care about
169  // things that are contained by-value in a structure that can have another
170  // structure as a member.
171  return true;
172}
173
174
175/// isSafeToConvert - Return true if it is safe to convert the specified record
176/// decl to IR and lay it out, false if doing so would cause us to get into a
177/// recursive compilation mess.
178static bool isSafeToConvert(const RecordDecl *RD, CodeGenTypes &CGT) {
179  // If no structs are being laid out, we can certainly do this one.
180  if (CGT.noRecordsBeingLaidOut()) return true;
181
182  llvm::SmallPtrSet<const RecordDecl*, 16> AlreadyChecked;
183  return isSafeToConvert(RD, CGT, AlreadyChecked);
184}
185
186/// isFuncParamTypeConvertible - Return true if the specified type in a
187/// function parameter or result position can be converted to an IR type at this
188/// point.  This boils down to being whether it is complete, as well as whether
189/// we've temporarily deferred expanding the type because we're in a recursive
190/// context.
191bool CodeGenTypes::isFuncParamTypeConvertible(QualType Ty) {
192  // Some ABIs cannot have their member pointers represented in IR unless
193  // certain circumstances have been reached.
194  if (const auto *MPT = Ty->getAs<MemberPointerType>())
195    return getCXXABI().isMemberPointerConvertible(MPT);
196
197  // If this isn't a tagged type, we can convert it!
198  const TagType *TT = Ty->getAs<TagType>();
199  if (!TT) return true;
200
201  // Incomplete types cannot be converted.
202  if (TT->isIncompleteType())
203    return false;
204
205  // If this is an enum, then it is always safe to convert.
206  const RecordType *RT = dyn_cast<RecordType>(TT);
207  if (!RT) return true;
208
209  // Otherwise, we have to be careful.  If it is a struct that we're in the
210  // process of expanding, then we can't convert the function type.  That's ok
211  // though because we must be in a pointer context under the struct, so we can
212  // just convert it to a dummy type.
213  //
214  // We decide this by checking whether ConvertRecordDeclType returns us an
215  // opaque type for a struct that we know is defined.
216  return isSafeToConvert(RT->getDecl(), *this);
217}
218
219
220/// Code to verify a given function type is complete, i.e. the return type
221/// and all of the parameter types are complete.  Also check to see if we are in
222/// a RS_StructPointer context, and if so whether any struct types have been
223/// pended.  If so, we don't want to ask the ABI lowering code to handle a type
224/// that cannot be converted to an IR type.
225bool CodeGenTypes::isFuncTypeConvertible(const FunctionType *FT) {
226  if (!isFuncParamTypeConvertible(FT->getReturnType()))
227    return false;
228
229  if (const FunctionProtoType *FPT = dyn_cast<FunctionProtoType>(FT))
230    for (unsigned i = 0, e = FPT->getNumParams(); i != e; i++)
231      if (!isFuncParamTypeConvertible(FPT->getParamType(i)))
232        return false;
233
234  return true;
235}
236
237/// UpdateCompletedType - When we find the full definition for a TagDecl,
238/// replace the 'opaque' type we previously made for it if applicable.
239void CodeGenTypes::UpdateCompletedType(const TagDecl *TD) {
240  // If this is an enum being completed, then we flush all non-struct types from
241  // the cache.  This allows function types and other things that may be derived
242  // from the enum to be recomputed.
243  if (const EnumDecl *ED = dyn_cast<EnumDecl>(TD)) {
244    // Only flush the cache if we've actually already converted this type.
245    if (TypeCache.count(ED->getTypeForDecl())) {
246      // Okay, we formed some types based on this.  We speculated that the enum
247      // would be lowered to i32, so we only need to flush the cache if this
248      // didn't happen.
249      if (!ConvertType(ED->getIntegerType())->isIntegerTy(32))
250        TypeCache.clear();
251    }
252    // If necessary, provide the full definition of a type only used with a
253    // declaration so far.
254    if (CGDebugInfo *DI = CGM.getModuleDebugInfo())
255      DI->completeType(ED);
256    return;
257  }
258
259  // If we completed a RecordDecl that we previously used and converted to an
260  // anonymous type, then go ahead and complete it now.
261  const RecordDecl *RD = cast<RecordDecl>(TD);
262  if (RD->isDependentType()) return;
263
264  // Only complete it if we converted it already.  If we haven't converted it
265  // yet, we'll just do it lazily.
266  if (RecordDeclTypes.count(Context.getTagDeclType(RD).getTypePtr()))
267    ConvertRecordDeclType(RD);
268
269  // If necessary, provide the full definition of a type only used with a
270  // declaration so far.
271  if (CGDebugInfo *DI = CGM.getModuleDebugInfo())
272    DI->completeType(RD);
273}
274
275void CodeGenTypes::RefreshTypeCacheForClass(const CXXRecordDecl *RD) {
276  QualType T = Context.getRecordType(RD);
277  T = Context.getCanonicalType(T);
278
279  const Type *Ty = T.getTypePtr();
280  if (RecordsWithOpaqueMemberPointers.count(Ty)) {
281    TypeCache.clear();
282    RecordsWithOpaqueMemberPointers.clear();
283  }
284}
285
286static llvm::Type *getTypeForFormat(llvm::LLVMContext &VMContext,
287                                    const llvm::fltSemantics &format,
288                                    bool UseNativeHalf = false) {
289  if (&format == &llvm::APFloat::IEEEhalf) {
290    if (UseNativeHalf)
291      return llvm::Type::getHalfTy(VMContext);
292    else
293      return llvm::Type::getInt16Ty(VMContext);
294  }
295  if (&format == &llvm::APFloat::IEEEsingle)
296    return llvm::Type::getFloatTy(VMContext);
297  if (&format == &llvm::APFloat::IEEEdouble)
298    return llvm::Type::getDoubleTy(VMContext);
299  if (&format == &llvm::APFloat::IEEEquad)
300    return llvm::Type::getFP128Ty(VMContext);
301  if (&format == &llvm::APFloat::PPCDoubleDouble)
302    return llvm::Type::getPPC_FP128Ty(VMContext);
303  if (&format == &llvm::APFloat::x87DoubleExtended)
304    return llvm::Type::getX86_FP80Ty(VMContext);
305  llvm_unreachable("Unknown float format!");
306}
307
308llvm::Type *CodeGenTypes::ConvertFunctionType(QualType QFT,
309                                              const FunctionDecl *FD) {
310  assert(QFT.isCanonical());
311  const Type *Ty = QFT.getTypePtr();
312  const FunctionType *FT = cast<FunctionType>(QFT.getTypePtr());
313  // First, check whether we can build the full function type.  If the
314  // function type depends on an incomplete type (e.g. a struct or enum), we
315  // cannot lower the function type.
316  if (!isFuncTypeConvertible(FT)) {
317    // This function's type depends on an incomplete tag type.
318
319    // Force conversion of all the relevant record types, to make sure
320    // we re-convert the FunctionType when appropriate.
321    if (const RecordType *RT = FT->getReturnType()->getAs<RecordType>())
322      ConvertRecordDeclType(RT->getDecl());
323    if (const FunctionProtoType *FPT = dyn_cast<FunctionProtoType>(FT))
324      for (unsigned i = 0, e = FPT->getNumParams(); i != e; i++)
325        if (const RecordType *RT = FPT->getParamType(i)->getAs<RecordType>())
326          ConvertRecordDeclType(RT->getDecl());
327
328    SkippedLayout = true;
329
330    // Return a placeholder type.
331    return llvm::StructType::get(getLLVMContext());
332  }
333
334  // While we're converting the parameter types for a function, we don't want
335  // to recursively convert any pointed-to structs.  Converting directly-used
336  // structs is ok though.
337  if (!RecordsBeingLaidOut.insert(Ty).second) {
338    SkippedLayout = true;
339    return llvm::StructType::get(getLLVMContext());
340  }
341
342  // The function type can be built; call the appropriate routines to
343  // build it.
344  const CGFunctionInfo *FI;
345  if (const FunctionProtoType *FPT = dyn_cast<FunctionProtoType>(FT)) {
346    FI = &arrangeFreeFunctionType(
347        CanQual<FunctionProtoType>::CreateUnsafe(QualType(FPT, 0)), FD);
348  } else {
349    const FunctionNoProtoType *FNPT = cast<FunctionNoProtoType>(FT);
350    FI = &arrangeFreeFunctionType(
351        CanQual<FunctionNoProtoType>::CreateUnsafe(QualType(FNPT, 0)));
352  }
353
354  llvm::Type *ResultType = nullptr;
355  // If there is something higher level prodding our CGFunctionInfo, then
356  // don't recurse into it again.
357  if (FunctionsBeingProcessed.count(FI)) {
358
359    ResultType = llvm::StructType::get(getLLVMContext());
360    SkippedLayout = true;
361  } else {
362
363    // Otherwise, we're good to go, go ahead and convert it.
364    ResultType = GetFunctionType(*FI);
365  }
366
367  RecordsBeingLaidOut.erase(Ty);
368
369  if (SkippedLayout)
370    TypeCache.clear();
371
372  if (RecordsBeingLaidOut.empty())
373    while (!DeferredRecords.empty())
374      ConvertRecordDeclType(DeferredRecords.pop_back_val());
375  return ResultType;
376}
377
378/// ConvertType - Convert the specified type to its LLVM form.
379llvm::Type *CodeGenTypes::ConvertType(QualType T) {
380  T = Context.getCanonicalType(T);
381
382  const Type *Ty = T.getTypePtr();
383
384  // RecordTypes are cached and processed specially.
385  if (const RecordType *RT = dyn_cast<RecordType>(Ty))
386    return ConvertRecordDeclType(RT->getDecl());
387
388  // See if type is already cached.
389  llvm::DenseMap<const Type *, llvm::Type *>::iterator TCI = TypeCache.find(Ty);
390  // If type is found in map then use it. Otherwise, convert type T.
391  if (TCI != TypeCache.end())
392    return TCI->second;
393
394  // If we don't have it in the cache, convert it now.
395  llvm::Type *ResultType = nullptr;
396  switch (Ty->getTypeClass()) {
397  case Type::Record: // Handled above.
398#define TYPE(Class, Base)
399#define ABSTRACT_TYPE(Class, Base)
400#define NON_CANONICAL_TYPE(Class, Base) case Type::Class:
401#define DEPENDENT_TYPE(Class, Base) case Type::Class:
402#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base) case Type::Class:
403#include "clang/AST/TypeNodes.def"
404    llvm_unreachable("Non-canonical or dependent types aren't possible.");
405
406  case Type::Builtin: {
407    switch (cast<BuiltinType>(Ty)->getKind()) {
408    case BuiltinType::Void:
409    case BuiltinType::ObjCId:
410    case BuiltinType::ObjCClass:
411    case BuiltinType::ObjCSel:
412      // LLVM void type can only be used as the result of a function call.  Just
413      // map to the same as char.
414      ResultType = llvm::Type::getInt8Ty(getLLVMContext());
415      break;
416
417    case BuiltinType::Bool:
418      // Note that we always return bool as i1 for use as a scalar type.
419      ResultType = llvm::Type::getInt1Ty(getLLVMContext());
420      break;
421
422    case BuiltinType::Char_S:
423    case BuiltinType::Char_U:
424    case BuiltinType::SChar:
425    case BuiltinType::UChar:
426    case BuiltinType::Short:
427    case BuiltinType::UShort:
428    case BuiltinType::Int:
429    case BuiltinType::UInt:
430    case BuiltinType::Long:
431    case BuiltinType::ULong:
432    case BuiltinType::LongLong:
433    case BuiltinType::ULongLong:
434    case BuiltinType::WChar_S:
435    case BuiltinType::WChar_U:
436    case BuiltinType::Char16:
437    case BuiltinType::Char32:
438      ResultType = llvm::IntegerType::get(getLLVMContext(),
439                                 static_cast<unsigned>(Context.getTypeSize(T)));
440      break;
441
442    case BuiltinType::Half:
443      // Half FP can either be storage-only (lowered to i16) or native.
444      ResultType =
445          getTypeForFormat(getLLVMContext(), Context.getFloatTypeSemantics(T),
446                           Context.getLangOpts().NativeHalfType ||
447                               Context.getLangOpts().HalfArgsAndReturns);
448      break;
449    case BuiltinType::Float:
450    case BuiltinType::Double:
451    case BuiltinType::LongDouble:
452    case BuiltinType::Float128:
453      ResultType = getTypeForFormat(getLLVMContext(),
454                                    Context.getFloatTypeSemantics(T),
455                                    /* UseNativeHalf = */ false);
456      break;
457
458    case BuiltinType::NullPtr:
459      // Model std::nullptr_t as i8*
460      ResultType = llvm::Type::getInt8PtrTy(getLLVMContext());
461      break;
462
463    case BuiltinType::UInt128:
464    case BuiltinType::Int128:
465      ResultType = llvm::IntegerType::get(getLLVMContext(), 128);
466      break;
467
468#define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
469    case BuiltinType::Id:
470#include "clang/Basic/OpenCLImageTypes.def"
471    case BuiltinType::OCLSampler:
472    case BuiltinType::OCLEvent:
473    case BuiltinType::OCLClkEvent:
474    case BuiltinType::OCLQueue:
475    case BuiltinType::OCLNDRange:
476    case BuiltinType::OCLReserveID:
477      ResultType = CGM.getOpenCLRuntime().convertOpenCLSpecificType(Ty);
478      break;
479
480    case BuiltinType::Dependent:
481#define BUILTIN_TYPE(Id, SingletonId)
482#define PLACEHOLDER_TYPE(Id, SingletonId) \
483    case BuiltinType::Id:
484#include "clang/AST/BuiltinTypes.def"
485      llvm_unreachable("Unexpected placeholder builtin type!");
486    }
487    break;
488  }
489  case Type::Auto:
490    llvm_unreachable("Unexpected undeduced auto type!");
491  case Type::Complex: {
492    llvm::Type *EltTy = ConvertType(cast<ComplexType>(Ty)->getElementType());
493    ResultType = llvm::StructType::get(EltTy, EltTy, nullptr);
494    break;
495  }
496  case Type::LValueReference:
497  case Type::RValueReference: {
498    const ReferenceType *RTy = cast<ReferenceType>(Ty);
499    QualType ETy = RTy->getPointeeType();
500    llvm::Type *PointeeType = ConvertTypeForMem(ETy);
501    unsigned AS = Context.getTargetAddressSpace(ETy);
502    ResultType = llvm::PointerType::get(PointeeType, AS);
503    break;
504  }
505  case Type::Pointer: {
506    const PointerType *PTy = cast<PointerType>(Ty);
507    QualType ETy = PTy->getPointeeType();
508    llvm::Type *PointeeType = ConvertTypeForMem(ETy);
509    if (PointeeType->isVoidTy())
510      PointeeType = llvm::Type::getInt8Ty(getLLVMContext());
511    unsigned AS = Context.getTargetAddressSpace(ETy);
512    ResultType = llvm::PointerType::get(PointeeType, AS);
513    break;
514  }
515
516  case Type::VariableArray: {
517    const VariableArrayType *A = cast<VariableArrayType>(Ty);
518    assert(A->getIndexTypeCVRQualifiers() == 0 &&
519           "FIXME: We only handle trivial array types so far!");
520    // VLAs resolve to the innermost element type; this matches
521    // the return of alloca, and there isn't any obviously better choice.
522    ResultType = ConvertTypeForMem(A->getElementType());
523    break;
524  }
525  case Type::IncompleteArray: {
526    const IncompleteArrayType *A = cast<IncompleteArrayType>(Ty);
527    assert(A->getIndexTypeCVRQualifiers() == 0 &&
528           "FIXME: We only handle trivial array types so far!");
529    // int X[] -> [0 x int], unless the element type is not sized.  If it is
530    // unsized (e.g. an incomplete struct) just use [0 x i8].
531    ResultType = ConvertTypeForMem(A->getElementType());
532    if (!ResultType->isSized()) {
533      SkippedLayout = true;
534      ResultType = llvm::Type::getInt8Ty(getLLVMContext());
535    }
536    ResultType = llvm::ArrayType::get(ResultType, 0);
537    break;
538  }
539  case Type::ConstantArray: {
540    const ConstantArrayType *A = cast<ConstantArrayType>(Ty);
541    llvm::Type *EltTy = ConvertTypeForMem(A->getElementType());
542
543    // Lower arrays of undefined struct type to arrays of i8 just to have a
544    // concrete type.
545    if (!EltTy->isSized()) {
546      SkippedLayout = true;
547      EltTy = llvm::Type::getInt8Ty(getLLVMContext());
548    }
549
550    ResultType = llvm::ArrayType::get(EltTy, A->getSize().getZExtValue());
551    break;
552  }
553  case Type::ExtVector:
554  case Type::Vector: {
555    const VectorType *VT = cast<VectorType>(Ty);
556    ResultType = llvm::VectorType::get(ConvertType(VT->getElementType()),
557                                       VT->getNumElements());
558    break;
559  }
560  case Type::FunctionNoProto:
561  case Type::FunctionProto:
562    ResultType = ConvertFunctionType(T);
563    break;
564  case Type::ObjCObject:
565    ResultType = ConvertType(cast<ObjCObjectType>(Ty)->getBaseType());
566    break;
567
568  case Type::ObjCInterface: {
569    // Objective-C interfaces are always opaque (outside of the
570    // runtime, which can do whatever it likes); we never refine
571    // these.
572    llvm::Type *&T = InterfaceTypes[cast<ObjCInterfaceType>(Ty)];
573    if (!T)
574      T = llvm::StructType::create(getLLVMContext());
575    ResultType = T;
576    break;
577  }
578
579  case Type::ObjCObjectPointer: {
580    // Protocol qualifications do not influence the LLVM type, we just return a
581    // pointer to the underlying interface type. We don't need to worry about
582    // recursive conversion.
583    llvm::Type *T =
584      ConvertTypeForMem(cast<ObjCObjectPointerType>(Ty)->getPointeeType());
585    ResultType = T->getPointerTo();
586    break;
587  }
588
589  case Type::Enum: {
590    const EnumDecl *ED = cast<EnumType>(Ty)->getDecl();
591    if (ED->isCompleteDefinition() || ED->isFixed())
592      return ConvertType(ED->getIntegerType());
593    // Return a placeholder 'i32' type.  This can be changed later when the
594    // type is defined (see UpdateCompletedType), but is likely to be the
595    // "right" answer.
596    ResultType = llvm::Type::getInt32Ty(getLLVMContext());
597    break;
598  }
599
600  case Type::BlockPointer: {
601    const QualType FTy = cast<BlockPointerType>(Ty)->getPointeeType();
602    llvm::Type *PointeeType = ConvertTypeForMem(FTy);
603    unsigned AS = Context.getTargetAddressSpace(FTy);
604    ResultType = llvm::PointerType::get(PointeeType, AS);
605    break;
606  }
607
608  case Type::MemberPointer: {
609    auto *MPTy = cast<MemberPointerType>(Ty);
610    if (!getCXXABI().isMemberPointerConvertible(MPTy)) {
611      RecordsWithOpaqueMemberPointers.insert(MPTy->getClass());
612      ResultType = llvm::StructType::create(getLLVMContext());
613    } else {
614      ResultType = getCXXABI().ConvertMemberPointerType(MPTy);
615    }
616    break;
617  }
618
619  case Type::Atomic: {
620    QualType valueType = cast<AtomicType>(Ty)->getValueType();
621    ResultType = ConvertTypeForMem(valueType);
622
623    // Pad out to the inflated size if necessary.
624    uint64_t valueSize = Context.getTypeSize(valueType);
625    uint64_t atomicSize = Context.getTypeSize(Ty);
626    if (valueSize != atomicSize) {
627      assert(valueSize < atomicSize);
628      llvm::Type *elts[] = {
629        ResultType,
630        llvm::ArrayType::get(CGM.Int8Ty, (atomicSize - valueSize) / 8)
631      };
632      ResultType = llvm::StructType::get(getLLVMContext(),
633                                         llvm::makeArrayRef(elts));
634    }
635    break;
636  }
637  case Type::Pipe: {
638    ResultType = CGM.getOpenCLRuntime().getPipeType();
639    break;
640  }
641  }
642
643  assert(ResultType && "Didn't convert a type?");
644
645  TypeCache[Ty] = ResultType;
646  return ResultType;
647}
648
649bool CodeGenModule::isPaddedAtomicType(QualType type) {
650  return isPaddedAtomicType(type->castAs<AtomicType>());
651}
652
653bool CodeGenModule::isPaddedAtomicType(const AtomicType *type) {
654  return Context.getTypeSize(type) != Context.getTypeSize(type->getValueType());
655}
656
657/// ConvertRecordDeclType - Lay out a tagged decl type like struct or union.
658llvm::StructType *CodeGenTypes::ConvertRecordDeclType(const RecordDecl *RD) {
659  // TagDecl's are not necessarily unique, instead use the (clang)
660  // type connected to the decl.
661  const Type *Key = Context.getTagDeclType(RD).getTypePtr();
662
663  llvm::StructType *&Entry = RecordDeclTypes[Key];
664
665  // If we don't have a StructType at all yet, create the forward declaration.
666  if (!Entry) {
667    Entry = llvm::StructType::create(getLLVMContext());
668    addRecordTypeName(RD, Entry, "");
669  }
670  llvm::StructType *Ty = Entry;
671
672  // If this is still a forward declaration, or the LLVM type is already
673  // complete, there's nothing more to do.
674  RD = RD->getDefinition();
675  if (!RD || !RD->isCompleteDefinition() || !Ty->isOpaque())
676    return Ty;
677
678  // If converting this type would cause us to infinitely loop, don't do it!
679  if (!isSafeToConvert(RD, *this)) {
680    DeferredRecords.push_back(RD);
681    return Ty;
682  }
683
684  // Okay, this is a definition of a type.  Compile the implementation now.
685  bool InsertResult = RecordsBeingLaidOut.insert(Key).second;
686  (void)InsertResult;
687  assert(InsertResult && "Recursively compiling a struct?");
688
689  // Force conversion of non-virtual base classes recursively.
690  if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD)) {
691    for (const auto &I : CRD->bases()) {
692      if (I.isVirtual()) continue;
693
694      ConvertRecordDeclType(I.getType()->getAs<RecordType>()->getDecl());
695    }
696  }
697
698  // Layout fields.
699  CGRecordLayout *Layout = ComputeRecordLayout(RD, Ty);
700  CGRecordLayouts[Key] = Layout;
701
702  // We're done laying out this struct.
703  bool EraseResult = RecordsBeingLaidOut.erase(Key); (void)EraseResult;
704  assert(EraseResult && "struct not in RecordsBeingLaidOut set?");
705
706  // If this struct blocked a FunctionType conversion, then recompute whatever
707  // was derived from that.
708  // FIXME: This is hugely overconservative.
709  if (SkippedLayout)
710    TypeCache.clear();
711
712  // If we're done converting the outer-most record, then convert any deferred
713  // structs as well.
714  if (RecordsBeingLaidOut.empty())
715    while (!DeferredRecords.empty())
716      ConvertRecordDeclType(DeferredRecords.pop_back_val());
717
718  return Ty;
719}
720
721/// getCGRecordLayout - Return record layout info for the given record decl.
722const CGRecordLayout &
723CodeGenTypes::getCGRecordLayout(const RecordDecl *RD) {
724  const Type *Key = Context.getTagDeclType(RD).getTypePtr();
725
726  const CGRecordLayout *Layout = CGRecordLayouts.lookup(Key);
727  if (!Layout) {
728    // Compute the type information.
729    ConvertRecordDeclType(RD);
730
731    // Now try again.
732    Layout = CGRecordLayouts.lookup(Key);
733  }
734
735  assert(Layout && "Unable to find record layout information for type");
736  return *Layout;
737}
738
739bool CodeGenTypes::isZeroInitializable(QualType T) {
740  // No need to check for member pointers when not compiling C++.
741  if (!Context.getLangOpts().CPlusPlus)
742    return true;
743
744  if (const auto *AT = Context.getAsArrayType(T)) {
745    if (isa<IncompleteArrayType>(AT))
746      return true;
747    if (const auto *CAT = dyn_cast<ConstantArrayType>(AT))
748      if (Context.getConstantArrayElementCount(CAT) == 0)
749        return true;
750    T = Context.getBaseElementType(T);
751  }
752
753  // Records are non-zero-initializable if they contain any
754  // non-zero-initializable subobjects.
755  if (const RecordType *RT = T->getAs<RecordType>()) {
756    const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
757    return isZeroInitializable(RD);
758  }
759
760  // We have to ask the ABI about member pointers.
761  if (const MemberPointerType *MPT = T->getAs<MemberPointerType>())
762    return getCXXABI().isZeroInitializable(MPT);
763
764  // Everything else is okay.
765  return true;
766}
767
768bool CodeGenTypes::isZeroInitializable(const RecordDecl *RD) {
769  return getCGRecordLayout(RD).isZeroInitializable();
770}
771