xref: /llvm-project/clang/lib/CodeGen/CodeGenModule.cpp (revision a637fb8ccdecd5b0a1171f262b48d62efe9452bd)
1 //===--- CodeGenModule.cpp - Emit LLVM Code from ASTs for a Module --------===//
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 coordinates the per-module state used while generating code.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "CodeGenModule.h"
15 #include "CGCUDARuntime.h"
16 #include "CGCXXABI.h"
17 #include "CGCall.h"
18 #include "CGDebugInfo.h"
19 #include "CGObjCRuntime.h"
20 #include "CGOpenCLRuntime.h"
21 #include "CodeGenFunction.h"
22 #include "CodeGenTBAA.h"
23 #include "TargetInfo.h"
24 #include "clang/AST/ASTContext.h"
25 #include "clang/AST/CharUnits.h"
26 #include "clang/AST/DeclCXX.h"
27 #include "clang/AST/DeclObjC.h"
28 #include "clang/AST/DeclTemplate.h"
29 #include "clang/AST/Mangle.h"
30 #include "clang/AST/RecordLayout.h"
31 #include "clang/AST/RecursiveASTVisitor.h"
32 #include "clang/Basic/Builtins.h"
33 #include "clang/Basic/CharInfo.h"
34 #include "clang/Basic/Diagnostic.h"
35 #include "clang/Basic/Module.h"
36 #include "clang/Basic/SourceManager.h"
37 #include "clang/Basic/TargetInfo.h"
38 #include "clang/Frontend/CodeGenOptions.h"
39 #include "llvm/ADT/APSInt.h"
40 #include "llvm/ADT/Triple.h"
41 #include "llvm/IR/CallingConv.h"
42 #include "llvm/IR/DataLayout.h"
43 #include "llvm/IR/Intrinsics.h"
44 #include "llvm/IR/LLVMContext.h"
45 #include "llvm/IR/Module.h"
46 #include "llvm/Support/CallSite.h"
47 #include "llvm/Support/ConvertUTF.h"
48 #include "llvm/Support/ErrorHandling.h"
49 #include "llvm/Target/Mangler.h"
50 
51 using namespace clang;
52 using namespace CodeGen;
53 
54 static const char AnnotationSection[] = "llvm.metadata";
55 
56 static CGCXXABI &createCXXABI(CodeGenModule &CGM) {
57   switch (CGM.getTarget().getCXXABI().getKind()) {
58   case TargetCXXABI::GenericAArch64:
59   case TargetCXXABI::GenericARM:
60   case TargetCXXABI::iOS:
61   case TargetCXXABI::GenericItanium:
62     return *CreateItaniumCXXABI(CGM);
63   case TargetCXXABI::Microsoft:
64     return *CreateMicrosoftCXXABI(CGM);
65   }
66 
67   llvm_unreachable("invalid C++ ABI kind");
68 }
69 
70 
71 CodeGenModule::CodeGenModule(ASTContext &C, const CodeGenOptions &CGO,
72                              llvm::Module &M, const llvm::DataLayout &TD,
73                              DiagnosticsEngine &diags)
74   : Context(C), LangOpts(C.getLangOpts()), CodeGenOpts(CGO), TheModule(M),
75     Diags(diags), TheDataLayout(TD), Target(C.getTargetInfo()),
76     ABI(createCXXABI(*this)), VMContext(M.getContext()), TBAA(0),
77     TheTargetCodeGenInfo(0), Types(*this), VTables(*this),
78     ObjCRuntime(0), OpenCLRuntime(0), CUDARuntime(0),
79     DebugInfo(0), ARCData(0), NoObjCARCExceptionsMetadata(0),
80     RRData(0), CFConstantStringClassRef(0),
81     ConstantStringClassRef(0), NSConstantStringType(0),
82     NSConcreteGlobalBlock(0), NSConcreteStackBlock(0),
83     BlockObjectAssign(0), BlockObjectDispose(0),
84     BlockDescriptorType(0), GenericBlockLiteralType(0),
85     LifetimeStartFn(0), LifetimeEndFn(0),
86     SanitizerBlacklist(CGO.SanitizerBlacklistFile),
87     SanOpts(SanitizerBlacklist.isIn(M) ?
88             SanitizerOptions::Disabled : LangOpts.Sanitize) {
89 
90   // Initialize the type cache.
91   llvm::LLVMContext &LLVMContext = M.getContext();
92   VoidTy = llvm::Type::getVoidTy(LLVMContext);
93   Int8Ty = llvm::Type::getInt8Ty(LLVMContext);
94   Int16Ty = llvm::Type::getInt16Ty(LLVMContext);
95   Int32Ty = llvm::Type::getInt32Ty(LLVMContext);
96   Int64Ty = llvm::Type::getInt64Ty(LLVMContext);
97   FloatTy = llvm::Type::getFloatTy(LLVMContext);
98   DoubleTy = llvm::Type::getDoubleTy(LLVMContext);
99   PointerWidthInBits = C.getTargetInfo().getPointerWidth(0);
100   PointerAlignInBytes =
101   C.toCharUnitsFromBits(C.getTargetInfo().getPointerAlign(0)).getQuantity();
102   IntTy = llvm::IntegerType::get(LLVMContext, C.getTargetInfo().getIntWidth());
103   IntPtrTy = llvm::IntegerType::get(LLVMContext, PointerWidthInBits);
104   Int8PtrTy = Int8Ty->getPointerTo(0);
105   Int8PtrPtrTy = Int8PtrTy->getPointerTo(0);
106 
107   RuntimeCC = getTargetCodeGenInfo().getABIInfo().getRuntimeCC();
108 
109   if (LangOpts.ObjC1)
110     createObjCRuntime();
111   if (LangOpts.OpenCL)
112     createOpenCLRuntime();
113   if (LangOpts.CUDA)
114     createCUDARuntime();
115 
116   // Enable TBAA unless it's suppressed. ThreadSanitizer needs TBAA even at O0.
117   if (SanOpts.Thread ||
118       (!CodeGenOpts.RelaxedAliasing && CodeGenOpts.OptimizationLevel > 0))
119     TBAA = new CodeGenTBAA(Context, VMContext, CodeGenOpts, getLangOpts(),
120                            ABI.getMangleContext());
121 
122   // If debug info or coverage generation is enabled, create the CGDebugInfo
123   // object.
124   if (CodeGenOpts.getDebugInfo() != CodeGenOptions::NoDebugInfo ||
125       CodeGenOpts.EmitGcovArcs ||
126       CodeGenOpts.EmitGcovNotes)
127     DebugInfo = new CGDebugInfo(*this);
128 
129   Block.GlobalUniqueCount = 0;
130 
131   if (C.getLangOpts().ObjCAutoRefCount)
132     ARCData = new ARCEntrypoints();
133   RRData = new RREntrypoints();
134 }
135 
136 CodeGenModule::~CodeGenModule() {
137   delete ObjCRuntime;
138   delete OpenCLRuntime;
139   delete CUDARuntime;
140   delete TheTargetCodeGenInfo;
141   delete &ABI;
142   delete TBAA;
143   delete DebugInfo;
144   delete ARCData;
145   delete RRData;
146 }
147 
148 void CodeGenModule::createObjCRuntime() {
149   // This is just isGNUFamily(), but we want to force implementors of
150   // new ABIs to decide how best to do this.
151   switch (LangOpts.ObjCRuntime.getKind()) {
152   case ObjCRuntime::GNUstep:
153   case ObjCRuntime::GCC:
154   case ObjCRuntime::ObjFW:
155     ObjCRuntime = CreateGNUObjCRuntime(*this);
156     return;
157 
158   case ObjCRuntime::FragileMacOSX:
159   case ObjCRuntime::MacOSX:
160   case ObjCRuntime::iOS:
161     ObjCRuntime = CreateMacObjCRuntime(*this);
162     return;
163   }
164   llvm_unreachable("bad runtime kind");
165 }
166 
167 void CodeGenModule::createOpenCLRuntime() {
168   OpenCLRuntime = new CGOpenCLRuntime(*this);
169 }
170 
171 void CodeGenModule::createCUDARuntime() {
172   CUDARuntime = CreateNVCUDARuntime(*this);
173 }
174 
175 void CodeGenModule::Release() {
176   EmitDeferred();
177   EmitCXXGlobalInitFunc();
178   EmitCXXGlobalDtorFunc();
179   EmitCXXThreadLocalInitFunc();
180   if (ObjCRuntime)
181     if (llvm::Function *ObjCInitFunction = ObjCRuntime->ModuleInitFunction())
182       AddGlobalCtor(ObjCInitFunction);
183   EmitCtorList(GlobalCtors, "llvm.global_ctors");
184   EmitCtorList(GlobalDtors, "llvm.global_dtors");
185   EmitGlobalAnnotations();
186   EmitStaticExternCAliases();
187   EmitLLVMUsed();
188 
189   if (CodeGenOpts.Autolink &&
190       (Context.getLangOpts().Modules || !LinkerOptionsMetadata.empty())) {
191     EmitModuleLinkOptions();
192   }
193 
194   SimplifyPersonality();
195 
196   if (getCodeGenOpts().EmitDeclMetadata)
197     EmitDeclMetadata();
198 
199   if (getCodeGenOpts().EmitGcovArcs || getCodeGenOpts().EmitGcovNotes)
200     EmitCoverageFile();
201 
202   if (DebugInfo)
203     DebugInfo->finalize();
204 }
205 
206 void CodeGenModule::UpdateCompletedType(const TagDecl *TD) {
207   // Make sure that this type is translated.
208   Types.UpdateCompletedType(TD);
209 }
210 
211 llvm::MDNode *CodeGenModule::getTBAAInfo(QualType QTy) {
212   if (!TBAA)
213     return 0;
214   return TBAA->getTBAAInfo(QTy);
215 }
216 
217 llvm::MDNode *CodeGenModule::getTBAAInfoForVTablePtr() {
218   if (!TBAA)
219     return 0;
220   return TBAA->getTBAAInfoForVTablePtr();
221 }
222 
223 llvm::MDNode *CodeGenModule::getTBAAStructInfo(QualType QTy) {
224   if (!TBAA)
225     return 0;
226   return TBAA->getTBAAStructInfo(QTy);
227 }
228 
229 llvm::MDNode *CodeGenModule::getTBAAStructTypeInfo(QualType QTy) {
230   if (!TBAA)
231     return 0;
232   return TBAA->getTBAAStructTypeInfo(QTy);
233 }
234 
235 llvm::MDNode *CodeGenModule::getTBAAStructTagInfo(QualType BaseTy,
236                                                   llvm::MDNode *AccessN,
237                                                   uint64_t O) {
238   if (!TBAA)
239     return 0;
240   return TBAA->getTBAAStructTagInfo(BaseTy, AccessN, O);
241 }
242 
243 /// Decorate the instruction with a TBAA tag. For scalar TBAA, the tag
244 /// is the same as the type. For struct-path aware TBAA, the tag
245 /// is different from the type: base type, access type and offset.
246 /// When ConvertTypeToTag is true, we create a tag based on the scalar type.
247 void CodeGenModule::DecorateInstruction(llvm::Instruction *Inst,
248                                         llvm::MDNode *TBAAInfo,
249                                         bool ConvertTypeToTag) {
250   if (ConvertTypeToTag && TBAA && CodeGenOpts.StructPathTBAA)
251     Inst->setMetadata(llvm::LLVMContext::MD_tbaa,
252                       TBAA->getTBAAScalarTagInfo(TBAAInfo));
253   else
254     Inst->setMetadata(llvm::LLVMContext::MD_tbaa, TBAAInfo);
255 }
256 
257 void CodeGenModule::Error(SourceLocation loc, StringRef error) {
258   unsigned diagID = getDiags().getCustomDiagID(DiagnosticsEngine::Error, error);
259   getDiags().Report(Context.getFullLoc(loc), diagID);
260 }
261 
262 /// ErrorUnsupported - Print out an error that codegen doesn't support the
263 /// specified stmt yet.
264 void CodeGenModule::ErrorUnsupported(const Stmt *S, const char *Type,
265                                      bool OmitOnError) {
266   if (OmitOnError && getDiags().hasErrorOccurred())
267     return;
268   unsigned DiagID = getDiags().getCustomDiagID(DiagnosticsEngine::Error,
269                                                "cannot compile this %0 yet");
270   std::string Msg = Type;
271   getDiags().Report(Context.getFullLoc(S->getLocStart()), DiagID)
272     << Msg << S->getSourceRange();
273 }
274 
275 /// ErrorUnsupported - Print out an error that codegen doesn't support the
276 /// specified decl yet.
277 void CodeGenModule::ErrorUnsupported(const Decl *D, const char *Type,
278                                      bool OmitOnError) {
279   if (OmitOnError && getDiags().hasErrorOccurred())
280     return;
281   unsigned DiagID = getDiags().getCustomDiagID(DiagnosticsEngine::Error,
282                                                "cannot compile this %0 yet");
283   std::string Msg = Type;
284   getDiags().Report(Context.getFullLoc(D->getLocation()), DiagID) << Msg;
285 }
286 
287 llvm::ConstantInt *CodeGenModule::getSize(CharUnits size) {
288   return llvm::ConstantInt::get(SizeTy, size.getQuantity());
289 }
290 
291 void CodeGenModule::setGlobalVisibility(llvm::GlobalValue *GV,
292                                         const NamedDecl *D) const {
293   // Internal definitions always have default visibility.
294   if (GV->hasLocalLinkage()) {
295     GV->setVisibility(llvm::GlobalValue::DefaultVisibility);
296     return;
297   }
298 
299   // Set visibility for definitions.
300   LinkageInfo LV = D->getLinkageAndVisibility();
301   if (LV.isVisibilityExplicit() || !GV->hasAvailableExternallyLinkage())
302     GV->setVisibility(GetLLVMVisibility(LV.getVisibility()));
303 }
304 
305 static llvm::GlobalVariable::ThreadLocalMode GetLLVMTLSModel(StringRef S) {
306   return llvm::StringSwitch<llvm::GlobalVariable::ThreadLocalMode>(S)
307       .Case("global-dynamic", llvm::GlobalVariable::GeneralDynamicTLSModel)
308       .Case("local-dynamic", llvm::GlobalVariable::LocalDynamicTLSModel)
309       .Case("initial-exec", llvm::GlobalVariable::InitialExecTLSModel)
310       .Case("local-exec", llvm::GlobalVariable::LocalExecTLSModel);
311 }
312 
313 static llvm::GlobalVariable::ThreadLocalMode GetLLVMTLSModel(
314     CodeGenOptions::TLSModel M) {
315   switch (M) {
316   case CodeGenOptions::GeneralDynamicTLSModel:
317     return llvm::GlobalVariable::GeneralDynamicTLSModel;
318   case CodeGenOptions::LocalDynamicTLSModel:
319     return llvm::GlobalVariable::LocalDynamicTLSModel;
320   case CodeGenOptions::InitialExecTLSModel:
321     return llvm::GlobalVariable::InitialExecTLSModel;
322   case CodeGenOptions::LocalExecTLSModel:
323     return llvm::GlobalVariable::LocalExecTLSModel;
324   }
325   llvm_unreachable("Invalid TLS model!");
326 }
327 
328 void CodeGenModule::setTLSMode(llvm::GlobalVariable *GV,
329                                const VarDecl &D) const {
330   assert(D.getTLSKind() && "setting TLS mode on non-TLS var!");
331 
332   llvm::GlobalVariable::ThreadLocalMode TLM;
333   TLM = GetLLVMTLSModel(CodeGenOpts.getDefaultTLSModel());
334 
335   // Override the TLS model if it is explicitly specified.
336   if (D.hasAttr<TLSModelAttr>()) {
337     const TLSModelAttr *Attr = D.getAttr<TLSModelAttr>();
338     TLM = GetLLVMTLSModel(Attr->getModel());
339   }
340 
341   GV->setThreadLocalMode(TLM);
342 }
343 
344 /// Set the symbol visibility of type information (vtable and RTTI)
345 /// associated with the given type.
346 void CodeGenModule::setTypeVisibility(llvm::GlobalValue *GV,
347                                       const CXXRecordDecl *RD,
348                                       TypeVisibilityKind TVK) const {
349   setGlobalVisibility(GV, RD);
350 
351   if (!CodeGenOpts.HiddenWeakVTables)
352     return;
353 
354   // We never want to drop the visibility for RTTI names.
355   if (TVK == TVK_ForRTTIName)
356     return;
357 
358   // We want to drop the visibility to hidden for weak type symbols.
359   // This isn't possible if there might be unresolved references
360   // elsewhere that rely on this symbol being visible.
361 
362   // This should be kept roughly in sync with setThunkVisibility
363   // in CGVTables.cpp.
364 
365   // Preconditions.
366   if (GV->getLinkage() != llvm::GlobalVariable::LinkOnceODRLinkage ||
367       GV->getVisibility() != llvm::GlobalVariable::DefaultVisibility)
368     return;
369 
370   // Don't override an explicit visibility attribute.
371   if (RD->getExplicitVisibility(NamedDecl::VisibilityForType))
372     return;
373 
374   switch (RD->getTemplateSpecializationKind()) {
375   // We have to disable the optimization if this is an EI definition
376   // because there might be EI declarations in other shared objects.
377   case TSK_ExplicitInstantiationDefinition:
378   case TSK_ExplicitInstantiationDeclaration:
379     return;
380 
381   // Every use of a non-template class's type information has to emit it.
382   case TSK_Undeclared:
383     break;
384 
385   // In theory, implicit instantiations can ignore the possibility of
386   // an explicit instantiation declaration because there necessarily
387   // must be an EI definition somewhere with default visibility.  In
388   // practice, it's possible to have an explicit instantiation for
389   // an arbitrary template class, and linkers aren't necessarily able
390   // to deal with mixed-visibility symbols.
391   case TSK_ExplicitSpecialization:
392   case TSK_ImplicitInstantiation:
393     return;
394   }
395 
396   // If there's a key function, there may be translation units
397   // that don't have the key function's definition.  But ignore
398   // this if we're emitting RTTI under -fno-rtti.
399   if (!(TVK != TVK_ForRTTI) || LangOpts.RTTI) {
400     // FIXME: what should we do if we "lose" the key function during
401     // the emission of the file?
402     if (Context.getCurrentKeyFunction(RD))
403       return;
404   }
405 
406   // Otherwise, drop the visibility to hidden.
407   GV->setVisibility(llvm::GlobalValue::HiddenVisibility);
408   GV->setUnnamedAddr(true);
409 }
410 
411 StringRef CodeGenModule::getMangledName(GlobalDecl GD) {
412   const NamedDecl *ND = cast<NamedDecl>(GD.getDecl());
413 
414   StringRef &Str = MangledDeclNames[GD.getCanonicalDecl()];
415   if (!Str.empty())
416     return Str;
417 
418   if (!getCXXABI().getMangleContext().shouldMangleDeclName(ND)) {
419     IdentifierInfo *II = ND->getIdentifier();
420     assert(II && "Attempt to mangle unnamed decl.");
421 
422     Str = II->getName();
423     return Str;
424   }
425 
426   SmallString<256> Buffer;
427   llvm::raw_svector_ostream Out(Buffer);
428   if (const CXXConstructorDecl *D = dyn_cast<CXXConstructorDecl>(ND))
429     getCXXABI().getMangleContext().mangleCXXCtor(D, GD.getCtorType(), Out);
430   else if (const CXXDestructorDecl *D = dyn_cast<CXXDestructorDecl>(ND))
431     getCXXABI().getMangleContext().mangleCXXDtor(D, GD.getDtorType(), Out);
432   else if (const BlockDecl *BD = dyn_cast<BlockDecl>(ND))
433     getCXXABI().getMangleContext().mangleBlock(BD, Out,
434       dyn_cast_or_null<VarDecl>(initializedGlobalDecl.getDecl()));
435   else
436     getCXXABI().getMangleContext().mangleName(ND, Out);
437 
438   // Allocate space for the mangled name.
439   Out.flush();
440   size_t Length = Buffer.size();
441   char *Name = MangledNamesAllocator.Allocate<char>(Length);
442   std::copy(Buffer.begin(), Buffer.end(), Name);
443 
444   Str = StringRef(Name, Length);
445 
446   return Str;
447 }
448 
449 void CodeGenModule::getBlockMangledName(GlobalDecl GD, MangleBuffer &Buffer,
450                                         const BlockDecl *BD) {
451   MangleContext &MangleCtx = getCXXABI().getMangleContext();
452   const Decl *D = GD.getDecl();
453   llvm::raw_svector_ostream Out(Buffer.getBuffer());
454   if (D == 0)
455     MangleCtx.mangleGlobalBlock(BD,
456       dyn_cast_or_null<VarDecl>(initializedGlobalDecl.getDecl()), Out);
457   else if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(D))
458     MangleCtx.mangleCtorBlock(CD, GD.getCtorType(), BD, Out);
459   else if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(D))
460     MangleCtx.mangleDtorBlock(DD, GD.getDtorType(), BD, Out);
461   else
462     MangleCtx.mangleBlock(cast<DeclContext>(D), BD, Out);
463 }
464 
465 llvm::GlobalValue *CodeGenModule::GetGlobalValue(StringRef Name) {
466   return getModule().getNamedValue(Name);
467 }
468 
469 /// AddGlobalCtor - Add a function to the list that will be called before
470 /// main() runs.
471 void CodeGenModule::AddGlobalCtor(llvm::Function * Ctor, int Priority) {
472   // FIXME: Type coercion of void()* types.
473   GlobalCtors.push_back(std::make_pair(Ctor, Priority));
474 }
475 
476 /// AddGlobalDtor - Add a function to the list that will be called
477 /// when the module is unloaded.
478 void CodeGenModule::AddGlobalDtor(llvm::Function * Dtor, int Priority) {
479   // FIXME: Type coercion of void()* types.
480   GlobalDtors.push_back(std::make_pair(Dtor, Priority));
481 }
482 
483 void CodeGenModule::EmitCtorList(const CtorList &Fns, const char *GlobalName) {
484   // Ctor function type is void()*.
485   llvm::FunctionType* CtorFTy = llvm::FunctionType::get(VoidTy, false);
486   llvm::Type *CtorPFTy = llvm::PointerType::getUnqual(CtorFTy);
487 
488   // Get the type of a ctor entry, { i32, void ()* }.
489   llvm::StructType *CtorStructTy =
490     llvm::StructType::get(Int32Ty, llvm::PointerType::getUnqual(CtorFTy), NULL);
491 
492   // Construct the constructor and destructor arrays.
493   SmallVector<llvm::Constant*, 8> Ctors;
494   for (CtorList::const_iterator I = Fns.begin(), E = Fns.end(); I != E; ++I) {
495     llvm::Constant *S[] = {
496       llvm::ConstantInt::get(Int32Ty, I->second, false),
497       llvm::ConstantExpr::getBitCast(I->first, CtorPFTy)
498     };
499     Ctors.push_back(llvm::ConstantStruct::get(CtorStructTy, S));
500   }
501 
502   if (!Ctors.empty()) {
503     llvm::ArrayType *AT = llvm::ArrayType::get(CtorStructTy, Ctors.size());
504     new llvm::GlobalVariable(TheModule, AT, false,
505                              llvm::GlobalValue::AppendingLinkage,
506                              llvm::ConstantArray::get(AT, Ctors),
507                              GlobalName);
508   }
509 }
510 
511 llvm::GlobalValue::LinkageTypes
512 CodeGenModule::getFunctionLinkage(GlobalDecl GD) {
513   return getFunctionLinkage(cast<FunctionDecl>(GD.getDecl()));
514 }
515 
516 llvm::GlobalValue::LinkageTypes
517 CodeGenModule::getFunctionLinkage(const FunctionDecl *D) {
518   GVALinkage Linkage = getContext().GetGVALinkageForFunction(D);
519 
520   if (Linkage == GVA_Internal)
521     return llvm::Function::InternalLinkage;
522 
523   if (D->hasAttr<DLLExportAttr>())
524     return llvm::Function::DLLExportLinkage;
525 
526   if (D->hasAttr<WeakAttr>())
527     return llvm::Function::WeakAnyLinkage;
528 
529   // In C99 mode, 'inline' functions are guaranteed to have a strong
530   // definition somewhere else, so we can use available_externally linkage.
531   if (Linkage == GVA_C99Inline)
532     return llvm::Function::AvailableExternallyLinkage;
533 
534   // Note that Apple's kernel linker doesn't support symbol
535   // coalescing, so we need to avoid linkonce and weak linkages there.
536   // Normally, this means we just map to internal, but for explicit
537   // instantiations we'll map to external.
538 
539   // In C++, the compiler has to emit a definition in every translation unit
540   // that references the function.  We should use linkonce_odr because
541   // a) if all references in this translation unit are optimized away, we
542   // don't need to codegen it.  b) if the function persists, it needs to be
543   // merged with other definitions. c) C++ has the ODR, so we know the
544   // definition is dependable.
545   if (Linkage == GVA_CXXInline || Linkage == GVA_TemplateInstantiation)
546     return !Context.getLangOpts().AppleKext
547              ? llvm::Function::LinkOnceODRLinkage
548              : llvm::Function::InternalLinkage;
549 
550   // An explicit instantiation of a template has weak linkage, since
551   // explicit instantiations can occur in multiple translation units
552   // and must all be equivalent. However, we are not allowed to
553   // throw away these explicit instantiations.
554   if (Linkage == GVA_ExplicitTemplateInstantiation)
555     return !Context.getLangOpts().AppleKext
556              ? llvm::Function::WeakODRLinkage
557              : llvm::Function::ExternalLinkage;
558 
559   // Otherwise, we have strong external linkage.
560   assert(Linkage == GVA_StrongExternal);
561   return llvm::Function::ExternalLinkage;
562 }
563 
564 
565 /// SetFunctionDefinitionAttributes - Set attributes for a global.
566 ///
567 /// FIXME: This is currently only done for aliases and functions, but not for
568 /// variables (these details are set in EmitGlobalVarDefinition for variables).
569 void CodeGenModule::SetFunctionDefinitionAttributes(const FunctionDecl *D,
570                                                     llvm::GlobalValue *GV) {
571   SetCommonAttributes(D, GV);
572 }
573 
574 void CodeGenModule::SetLLVMFunctionAttributes(const Decl *D,
575                                               const CGFunctionInfo &Info,
576                                               llvm::Function *F) {
577   unsigned CallingConv;
578   AttributeListType AttributeList;
579   ConstructAttributeList(Info, D, AttributeList, CallingConv, false);
580   F->setAttributes(llvm::AttributeSet::get(getLLVMContext(), AttributeList));
581   F->setCallingConv(static_cast<llvm::CallingConv::ID>(CallingConv));
582 }
583 
584 /// Determines whether the language options require us to model
585 /// unwind exceptions.  We treat -fexceptions as mandating this
586 /// except under the fragile ObjC ABI with only ObjC exceptions
587 /// enabled.  This means, for example, that C with -fexceptions
588 /// enables this.
589 static bool hasUnwindExceptions(const LangOptions &LangOpts) {
590   // If exceptions are completely disabled, obviously this is false.
591   if (!LangOpts.Exceptions) return false;
592 
593   // If C++ exceptions are enabled, this is true.
594   if (LangOpts.CXXExceptions) return true;
595 
596   // If ObjC exceptions are enabled, this depends on the ABI.
597   if (LangOpts.ObjCExceptions) {
598     return LangOpts.ObjCRuntime.hasUnwindExceptions();
599   }
600 
601   return true;
602 }
603 
604 void CodeGenModule::SetLLVMFunctionAttributesForDefinition(const Decl *D,
605                                                            llvm::Function *F) {
606   llvm::AttrBuilder B;
607 
608   if (CodeGenOpts.UnwindTables)
609     B.addAttribute(llvm::Attribute::UWTable);
610 
611   if (!hasUnwindExceptions(LangOpts))
612     B.addAttribute(llvm::Attribute::NoUnwind);
613 
614   if (D->hasAttr<NakedAttr>()) {
615     // Naked implies noinline: we should not be inlining such functions.
616     B.addAttribute(llvm::Attribute::Naked);
617     B.addAttribute(llvm::Attribute::NoInline);
618   } else if (D->hasAttr<NoInlineAttr>()) {
619     B.addAttribute(llvm::Attribute::NoInline);
620   } else if ((D->hasAttr<AlwaysInlineAttr>() ||
621               D->hasAttr<ForceInlineAttr>()) &&
622              !F->getAttributes().hasAttribute(llvm::AttributeSet::FunctionIndex,
623                                               llvm::Attribute::NoInline)) {
624     // (noinline wins over always_inline, and we can't specify both in IR)
625     B.addAttribute(llvm::Attribute::AlwaysInline);
626   }
627 
628   if (D->hasAttr<ColdAttr>()) {
629     B.addAttribute(llvm::Attribute::OptimizeForSize);
630     B.addAttribute(llvm::Attribute::Cold);
631   }
632 
633   if (D->hasAttr<MinSizeAttr>())
634     B.addAttribute(llvm::Attribute::MinSize);
635 
636   if (LangOpts.getStackProtector() == LangOptions::SSPOn)
637     B.addAttribute(llvm::Attribute::StackProtect);
638   else if (LangOpts.getStackProtector() == LangOptions::SSPReq)
639     B.addAttribute(llvm::Attribute::StackProtectReq);
640 
641   // Add sanitizer attributes if function is not blacklisted.
642   if (!SanitizerBlacklist.isIn(*F)) {
643     // When AddressSanitizer is enabled, set SanitizeAddress attribute
644     // unless __attribute__((no_sanitize_address)) is used.
645     if (SanOpts.Address && !D->hasAttr<NoSanitizeAddressAttr>())
646       B.addAttribute(llvm::Attribute::SanitizeAddress);
647     // Same for ThreadSanitizer and __attribute__((no_sanitize_thread))
648     if (SanOpts.Thread && !D->hasAttr<NoSanitizeThreadAttr>()) {
649       B.addAttribute(llvm::Attribute::SanitizeThread);
650     }
651     // Same for MemorySanitizer and __attribute__((no_sanitize_memory))
652     if (SanOpts.Memory && !D->hasAttr<NoSanitizeMemoryAttr>())
653       B.addAttribute(llvm::Attribute::SanitizeMemory);
654   }
655 
656   F->addAttributes(llvm::AttributeSet::FunctionIndex,
657                    llvm::AttributeSet::get(
658                        F->getContext(), llvm::AttributeSet::FunctionIndex, B));
659 
660   if (isa<CXXConstructorDecl>(D) || isa<CXXDestructorDecl>(D))
661     F->setUnnamedAddr(true);
662   else if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(D))
663     if (MD->isVirtual())
664       F->setUnnamedAddr(true);
665 
666   unsigned alignment = D->getMaxAlignment() / Context.getCharWidth();
667   if (alignment)
668     F->setAlignment(alignment);
669 
670   // C++ ABI requires 2-byte alignment for member functions.
671   if (F->getAlignment() < 2 && isa<CXXMethodDecl>(D))
672     F->setAlignment(2);
673 }
674 
675 void CodeGenModule::SetCommonAttributes(const Decl *D,
676                                         llvm::GlobalValue *GV) {
677   if (const NamedDecl *ND = dyn_cast<NamedDecl>(D))
678     setGlobalVisibility(GV, ND);
679   else
680     GV->setVisibility(llvm::GlobalValue::DefaultVisibility);
681 
682   if (D->hasAttr<UsedAttr>())
683     AddUsedGlobal(GV);
684 
685   if (const SectionAttr *SA = D->getAttr<SectionAttr>())
686     GV->setSection(SA->getName());
687 
688   // Alias cannot have attributes. Filter them here.
689   if (!isa<llvm::GlobalAlias>(GV))
690     getTargetCodeGenInfo().SetTargetAttributes(D, GV, *this);
691 }
692 
693 void CodeGenModule::SetInternalFunctionAttributes(const Decl *D,
694                                                   llvm::Function *F,
695                                                   const CGFunctionInfo &FI) {
696   SetLLVMFunctionAttributes(D, FI, F);
697   SetLLVMFunctionAttributesForDefinition(D, F);
698 
699   F->setLinkage(llvm::Function::InternalLinkage);
700 
701   SetCommonAttributes(D, F);
702 }
703 
704 void CodeGenModule::SetFunctionAttributes(GlobalDecl GD,
705                                           llvm::Function *F,
706                                           bool IsIncompleteFunction) {
707   if (unsigned IID = F->getIntrinsicID()) {
708     // If this is an intrinsic function, set the function's attributes
709     // to the intrinsic's attributes.
710     F->setAttributes(llvm::Intrinsic::getAttributes(getLLVMContext(),
711                                                     (llvm::Intrinsic::ID)IID));
712     return;
713   }
714 
715   const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
716 
717   if (!IsIncompleteFunction)
718     SetLLVMFunctionAttributes(FD, getTypes().arrangeGlobalDeclaration(GD), F);
719 
720   if (getCXXABI().HasThisReturn(GD)) {
721     llvm::Type *RetTy = F->getReturnType();
722     assert(!F->arg_empty() &&
723            F->arg_begin()->getType()->canLosslesslyBitCastTo(RetTy) &&
724            "unexpected this return");
725     F->addAttribute(1, llvm::Attribute::Returned);
726   }
727 
728   // Only a few attributes are set on declarations; these may later be
729   // overridden by a definition.
730 
731   if (FD->hasAttr<DLLImportAttr>()) {
732     F->setLinkage(llvm::Function::DLLImportLinkage);
733   } else if (FD->hasAttr<WeakAttr>() ||
734              FD->isWeakImported()) {
735     // "extern_weak" is overloaded in LLVM; we probably should have
736     // separate linkage types for this.
737     F->setLinkage(llvm::Function::ExternalWeakLinkage);
738   } else {
739     F->setLinkage(llvm::Function::ExternalLinkage);
740 
741     LinkageInfo LV = FD->getLinkageAndVisibility();
742     if (LV.getLinkage() == ExternalLinkage && LV.isVisibilityExplicit()) {
743       F->setVisibility(GetLLVMVisibility(LV.getVisibility()));
744     }
745   }
746 
747   if (const SectionAttr *SA = FD->getAttr<SectionAttr>())
748     F->setSection(SA->getName());
749 }
750 
751 void CodeGenModule::AddUsedGlobal(llvm::GlobalValue *GV) {
752   assert(!GV->isDeclaration() &&
753          "Only globals with definition can force usage.");
754   LLVMUsed.push_back(GV);
755 }
756 
757 void CodeGenModule::EmitLLVMUsed() {
758   // Don't create llvm.used if there is no need.
759   if (LLVMUsed.empty())
760     return;
761 
762   // Convert LLVMUsed to what ConstantArray needs.
763   SmallVector<llvm::Constant*, 8> UsedArray;
764   UsedArray.resize(LLVMUsed.size());
765   for (unsigned i = 0, e = LLVMUsed.size(); i != e; ++i) {
766     UsedArray[i] =
767      llvm::ConstantExpr::getBitCast(cast<llvm::Constant>(&*LLVMUsed[i]),
768                                     Int8PtrTy);
769   }
770 
771   if (UsedArray.empty())
772     return;
773   llvm::ArrayType *ATy = llvm::ArrayType::get(Int8PtrTy, UsedArray.size());
774 
775   llvm::GlobalVariable *GV =
776     new llvm::GlobalVariable(getModule(), ATy, false,
777                              llvm::GlobalValue::AppendingLinkage,
778                              llvm::ConstantArray::get(ATy, UsedArray),
779                              "llvm.used");
780 
781   GV->setSection("llvm.metadata");
782 }
783 
784 void CodeGenModule::AppendLinkerOptions(StringRef Opts) {
785   llvm::Value *MDOpts = llvm::MDString::get(getLLVMContext(), Opts);
786   LinkerOptionsMetadata.push_back(llvm::MDNode::get(getLLVMContext(), MDOpts));
787 }
788 
789 void CodeGenModule::AddDetectMismatch(StringRef Name, StringRef Value) {
790   llvm::SmallString<32> Opt;
791   getTargetCodeGenInfo().getDetectMismatchOption(Name, Value, Opt);
792   llvm::Value *MDOpts = llvm::MDString::get(getLLVMContext(), Opt);
793   LinkerOptionsMetadata.push_back(llvm::MDNode::get(getLLVMContext(), MDOpts));
794 }
795 
796 void CodeGenModule::AddDependentLib(StringRef Lib) {
797   llvm::SmallString<24> Opt;
798   getTargetCodeGenInfo().getDependentLibraryOption(Lib, Opt);
799   llvm::Value *MDOpts = llvm::MDString::get(getLLVMContext(), Opt);
800   LinkerOptionsMetadata.push_back(llvm::MDNode::get(getLLVMContext(), MDOpts));
801 }
802 
803 /// \brief Add link options implied by the given module, including modules
804 /// it depends on, using a postorder walk.
805 static void addLinkOptionsPostorder(CodeGenModule &CGM,
806                                     Module *Mod,
807                                     SmallVectorImpl<llvm::Value *> &Metadata,
808                                     llvm::SmallPtrSet<Module *, 16> &Visited) {
809   // Import this module's parent.
810   if (Mod->Parent && Visited.insert(Mod->Parent)) {
811     addLinkOptionsPostorder(CGM, Mod->Parent, Metadata, Visited);
812   }
813 
814   // Import this module's dependencies.
815   for (unsigned I = Mod->Imports.size(); I > 0; --I) {
816     if (Visited.insert(Mod->Imports[I-1]))
817       addLinkOptionsPostorder(CGM, Mod->Imports[I-1], Metadata, Visited);
818   }
819 
820   // Add linker options to link against the libraries/frameworks
821   // described by this module.
822   llvm::LLVMContext &Context = CGM.getLLVMContext();
823   for (unsigned I = Mod->LinkLibraries.size(); I > 0; --I) {
824     // Link against a framework.  Frameworks are currently Darwin only, so we
825     // don't to ask TargetCodeGenInfo for the spelling of the linker option.
826     if (Mod->LinkLibraries[I-1].IsFramework) {
827       llvm::Value *Args[2] = {
828         llvm::MDString::get(Context, "-framework"),
829         llvm::MDString::get(Context, Mod->LinkLibraries[I-1].Library)
830       };
831 
832       Metadata.push_back(llvm::MDNode::get(Context, Args));
833       continue;
834     }
835 
836     // Link against a library.
837     llvm::SmallString<24> Opt;
838     CGM.getTargetCodeGenInfo().getDependentLibraryOption(
839       Mod->LinkLibraries[I-1].Library, Opt);
840     llvm::Value *OptString = llvm::MDString::get(Context, Opt);
841     Metadata.push_back(llvm::MDNode::get(Context, OptString));
842   }
843 }
844 
845 void CodeGenModule::EmitModuleLinkOptions() {
846   // Collect the set of all of the modules we want to visit to emit link
847   // options, which is essentially the imported modules and all of their
848   // non-explicit child modules.
849   llvm::SetVector<clang::Module *> LinkModules;
850   llvm::SmallPtrSet<clang::Module *, 16> Visited;
851   SmallVector<clang::Module *, 16> Stack;
852 
853   // Seed the stack with imported modules.
854   for (llvm::SetVector<clang::Module *>::iterator M = ImportedModules.begin(),
855                                                MEnd = ImportedModules.end();
856        M != MEnd; ++M) {
857     if (Visited.insert(*M))
858       Stack.push_back(*M);
859   }
860 
861   // Find all of the modules to import, making a little effort to prune
862   // non-leaf modules.
863   while (!Stack.empty()) {
864     clang::Module *Mod = Stack.back();
865     Stack.pop_back();
866 
867     bool AnyChildren = false;
868 
869     // Visit the submodules of this module.
870     for (clang::Module::submodule_iterator Sub = Mod->submodule_begin(),
871                                         SubEnd = Mod->submodule_end();
872          Sub != SubEnd; ++Sub) {
873       // Skip explicit children; they need to be explicitly imported to be
874       // linked against.
875       if ((*Sub)->IsExplicit)
876         continue;
877 
878       if (Visited.insert(*Sub)) {
879         Stack.push_back(*Sub);
880         AnyChildren = true;
881       }
882     }
883 
884     // We didn't find any children, so add this module to the list of
885     // modules to link against.
886     if (!AnyChildren) {
887       LinkModules.insert(Mod);
888     }
889   }
890 
891   // Add link options for all of the imported modules in reverse topological
892   // order.  We don't do anything to try to order import link flags with respect
893   // to linker options inserted by things like #pragma comment().
894   SmallVector<llvm::Value *, 16> MetadataArgs;
895   Visited.clear();
896   for (llvm::SetVector<clang::Module *>::iterator M = LinkModules.begin(),
897                                                MEnd = LinkModules.end();
898        M != MEnd; ++M) {
899     if (Visited.insert(*M))
900       addLinkOptionsPostorder(*this, *M, MetadataArgs, Visited);
901   }
902   std::reverse(MetadataArgs.begin(), MetadataArgs.end());
903   LinkerOptionsMetadata.append(MetadataArgs.begin(), MetadataArgs.end());
904 
905   // Add the linker options metadata flag.
906   getModule().addModuleFlag(llvm::Module::AppendUnique, "Linker Options",
907                             llvm::MDNode::get(getLLVMContext(),
908                                               LinkerOptionsMetadata));
909 }
910 
911 void CodeGenModule::EmitDeferred() {
912   // Emit code for any potentially referenced deferred decls.  Since a
913   // previously unused static decl may become used during the generation of code
914   // for a static function, iterate until no changes are made.
915 
916   while (true) {
917     if (!DeferredVTables.empty()) {
918       EmitDeferredVTables();
919 
920       // Emitting a v-table doesn't directly cause more v-tables to
921       // become deferred, although it can cause functions to be
922       // emitted that then need those v-tables.
923       assert(DeferredVTables.empty());
924     }
925 
926     // Stop if we're out of both deferred v-tables and deferred declarations.
927     if (DeferredDeclsToEmit.empty()) break;
928 
929     GlobalDecl D = DeferredDeclsToEmit.back();
930     DeferredDeclsToEmit.pop_back();
931 
932     // Check to see if we've already emitted this.  This is necessary
933     // for a couple of reasons: first, decls can end up in the
934     // deferred-decls queue multiple times, and second, decls can end
935     // up with definitions in unusual ways (e.g. by an extern inline
936     // function acquiring a strong function redefinition).  Just
937     // ignore these cases.
938     //
939     // TODO: That said, looking this up multiple times is very wasteful.
940     StringRef Name = getMangledName(D);
941     llvm::GlobalValue *CGRef = GetGlobalValue(Name);
942     assert(CGRef && "Deferred decl wasn't referenced?");
943 
944     if (!CGRef->isDeclaration())
945       continue;
946 
947     // GlobalAlias::isDeclaration() defers to the aliasee, but for our
948     // purposes an alias counts as a definition.
949     if (isa<llvm::GlobalAlias>(CGRef))
950       continue;
951 
952     // Otherwise, emit the definition and move on to the next one.
953     EmitGlobalDefinition(D);
954   }
955 }
956 
957 void CodeGenModule::EmitGlobalAnnotations() {
958   if (Annotations.empty())
959     return;
960 
961   // Create a new global variable for the ConstantStruct in the Module.
962   llvm::Constant *Array = llvm::ConstantArray::get(llvm::ArrayType::get(
963     Annotations[0]->getType(), Annotations.size()), Annotations);
964   llvm::GlobalValue *gv = new llvm::GlobalVariable(getModule(),
965     Array->getType(), false, llvm::GlobalValue::AppendingLinkage, Array,
966     "llvm.global.annotations");
967   gv->setSection(AnnotationSection);
968 }
969 
970 llvm::Constant *CodeGenModule::EmitAnnotationString(StringRef Str) {
971   llvm::StringMap<llvm::Constant*>::iterator i = AnnotationStrings.find(Str);
972   if (i != AnnotationStrings.end())
973     return i->second;
974 
975   // Not found yet, create a new global.
976   llvm::Constant *s = llvm::ConstantDataArray::getString(getLLVMContext(), Str);
977   llvm::GlobalValue *gv = new llvm::GlobalVariable(getModule(), s->getType(),
978     true, llvm::GlobalValue::PrivateLinkage, s, ".str");
979   gv->setSection(AnnotationSection);
980   gv->setUnnamedAddr(true);
981   AnnotationStrings[Str] = gv;
982   return gv;
983 }
984 
985 llvm::Constant *CodeGenModule::EmitAnnotationUnit(SourceLocation Loc) {
986   SourceManager &SM = getContext().getSourceManager();
987   PresumedLoc PLoc = SM.getPresumedLoc(Loc);
988   if (PLoc.isValid())
989     return EmitAnnotationString(PLoc.getFilename());
990   return EmitAnnotationString(SM.getBufferName(Loc));
991 }
992 
993 llvm::Constant *CodeGenModule::EmitAnnotationLineNo(SourceLocation L) {
994   SourceManager &SM = getContext().getSourceManager();
995   PresumedLoc PLoc = SM.getPresumedLoc(L);
996   unsigned LineNo = PLoc.isValid() ? PLoc.getLine() :
997     SM.getExpansionLineNumber(L);
998   return llvm::ConstantInt::get(Int32Ty, LineNo);
999 }
1000 
1001 llvm::Constant *CodeGenModule::EmitAnnotateAttr(llvm::GlobalValue *GV,
1002                                                 const AnnotateAttr *AA,
1003                                                 SourceLocation L) {
1004   // Get the globals for file name, annotation, and the line number.
1005   llvm::Constant *AnnoGV = EmitAnnotationString(AA->getAnnotation()),
1006                  *UnitGV = EmitAnnotationUnit(L),
1007                  *LineNoCst = EmitAnnotationLineNo(L);
1008 
1009   // Create the ConstantStruct for the global annotation.
1010   llvm::Constant *Fields[4] = {
1011     llvm::ConstantExpr::getBitCast(GV, Int8PtrTy),
1012     llvm::ConstantExpr::getBitCast(AnnoGV, Int8PtrTy),
1013     llvm::ConstantExpr::getBitCast(UnitGV, Int8PtrTy),
1014     LineNoCst
1015   };
1016   return llvm::ConstantStruct::getAnon(Fields);
1017 }
1018 
1019 void CodeGenModule::AddGlobalAnnotations(const ValueDecl *D,
1020                                          llvm::GlobalValue *GV) {
1021   assert(D->hasAttr<AnnotateAttr>() && "no annotate attribute");
1022   // Get the struct elements for these annotations.
1023   for (specific_attr_iterator<AnnotateAttr>
1024        ai = D->specific_attr_begin<AnnotateAttr>(),
1025        ae = D->specific_attr_end<AnnotateAttr>(); ai != ae; ++ai)
1026     Annotations.push_back(EmitAnnotateAttr(GV, *ai, D->getLocation()));
1027 }
1028 
1029 bool CodeGenModule::MayDeferGeneration(const ValueDecl *Global) {
1030   // Never defer when EmitAllDecls is specified.
1031   if (LangOpts.EmitAllDecls)
1032     return false;
1033 
1034   return !getContext().DeclMustBeEmitted(Global);
1035 }
1036 
1037 llvm::Constant *CodeGenModule::GetAddrOfUuidDescriptor(
1038     const CXXUuidofExpr* E) {
1039   // Sema has verified that IIDSource has a __declspec(uuid()), and that its
1040   // well-formed.
1041   StringRef Uuid;
1042   if (E->isTypeOperand())
1043     Uuid = CXXUuidofExpr::GetUuidAttrOfType(E->getTypeOperand())->getGuid();
1044   else {
1045     // Special case: __uuidof(0) means an all-zero GUID.
1046     Expr *Op = E->getExprOperand();
1047     if (!Op->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNull))
1048       Uuid = CXXUuidofExpr::GetUuidAttrOfType(Op->getType())->getGuid();
1049     else
1050       Uuid = "00000000-0000-0000-0000-000000000000";
1051   }
1052   std::string Name = "__uuid_" + Uuid.str();
1053 
1054   // Look for an existing global.
1055   if (llvm::GlobalVariable *GV = getModule().getNamedGlobal(Name))
1056     return GV;
1057 
1058   llvm::Constant *Init = EmitUuidofInitializer(Uuid, E->getType());
1059   assert(Init && "failed to initialize as constant");
1060 
1061   // GUIDs are assumed to be 16 bytes, spread over 4-2-2-8 bytes. However, the
1062   // first field is declared as "long", which for many targets is 8 bytes.
1063   // Those architectures are not supported. (With the MS abi, long is always 4
1064   // bytes.)
1065   llvm::Type *GuidType = getTypes().ConvertType(E->getType());
1066   if (Init->getType() != GuidType) {
1067     DiagnosticsEngine &Diags = getDiags();
1068     unsigned DiagID = Diags.getCustomDiagID(DiagnosticsEngine::Error,
1069         "__uuidof codegen is not supported on this architecture");
1070     Diags.Report(E->getExprLoc(), DiagID) << E->getSourceRange();
1071     Init = llvm::UndefValue::get(GuidType);
1072   }
1073 
1074   llvm::GlobalVariable *GV = new llvm::GlobalVariable(getModule(), GuidType,
1075       /*isConstant=*/true, llvm::GlobalValue::PrivateLinkage, Init, Name);
1076   GV->setUnnamedAddr(true);
1077   return GV;
1078 }
1079 
1080 llvm::Constant *CodeGenModule::GetWeakRefReference(const ValueDecl *VD) {
1081   const AliasAttr *AA = VD->getAttr<AliasAttr>();
1082   assert(AA && "No alias?");
1083 
1084   llvm::Type *DeclTy = getTypes().ConvertTypeForMem(VD->getType());
1085 
1086   // See if there is already something with the target's name in the module.
1087   llvm::GlobalValue *Entry = GetGlobalValue(AA->getAliasee());
1088   if (Entry) {
1089     unsigned AS = getContext().getTargetAddressSpace(VD->getType());
1090     return llvm::ConstantExpr::getBitCast(Entry, DeclTy->getPointerTo(AS));
1091   }
1092 
1093   llvm::Constant *Aliasee;
1094   if (isa<llvm::FunctionType>(DeclTy))
1095     Aliasee = GetOrCreateLLVMFunction(AA->getAliasee(), DeclTy,
1096                                       GlobalDecl(cast<FunctionDecl>(VD)),
1097                                       /*ForVTable=*/false);
1098   else
1099     Aliasee = GetOrCreateLLVMGlobal(AA->getAliasee(),
1100                                     llvm::PointerType::getUnqual(DeclTy), 0);
1101 
1102   llvm::GlobalValue* F = cast<llvm::GlobalValue>(Aliasee);
1103   F->setLinkage(llvm::Function::ExternalWeakLinkage);
1104   WeakRefReferences.insert(F);
1105 
1106   return Aliasee;
1107 }
1108 
1109 void CodeGenModule::EmitGlobal(GlobalDecl GD) {
1110   const ValueDecl *Global = cast<ValueDecl>(GD.getDecl());
1111 
1112   // Weak references don't produce any output by themselves.
1113   if (Global->hasAttr<WeakRefAttr>())
1114     return;
1115 
1116   // If this is an alias definition (which otherwise looks like a declaration)
1117   // emit it now.
1118   if (Global->hasAttr<AliasAttr>())
1119     return EmitAliasDefinition(GD);
1120 
1121   // If this is CUDA, be selective about which declarations we emit.
1122   if (LangOpts.CUDA) {
1123     if (CodeGenOpts.CUDAIsDevice) {
1124       if (!Global->hasAttr<CUDADeviceAttr>() &&
1125           !Global->hasAttr<CUDAGlobalAttr>() &&
1126           !Global->hasAttr<CUDAConstantAttr>() &&
1127           !Global->hasAttr<CUDASharedAttr>())
1128         return;
1129     } else {
1130       if (!Global->hasAttr<CUDAHostAttr>() && (
1131             Global->hasAttr<CUDADeviceAttr>() ||
1132             Global->hasAttr<CUDAConstantAttr>() ||
1133             Global->hasAttr<CUDASharedAttr>()))
1134         return;
1135     }
1136   }
1137 
1138   // Ignore declarations, they will be emitted on their first use.
1139   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Global)) {
1140     // Forward declarations are emitted lazily on first use.
1141     if (!FD->doesThisDeclarationHaveABody()) {
1142       if (!FD->doesDeclarationForceExternallyVisibleDefinition())
1143         return;
1144 
1145       const FunctionDecl *InlineDefinition = 0;
1146       FD->getBody(InlineDefinition);
1147 
1148       StringRef MangledName = getMangledName(GD);
1149       DeferredDecls.erase(MangledName);
1150       EmitGlobalDefinition(InlineDefinition);
1151       return;
1152     }
1153   } else {
1154     const VarDecl *VD = cast<VarDecl>(Global);
1155     assert(VD->isFileVarDecl() && "Cannot emit local var decl as global.");
1156 
1157     if (VD->isThisDeclarationADefinition() != VarDecl::Definition)
1158       return;
1159   }
1160 
1161   // Defer code generation when possible if this is a static definition, inline
1162   // function etc.  These we only want to emit if they are used.
1163   if (!MayDeferGeneration(Global)) {
1164     // Emit the definition if it can't be deferred.
1165     EmitGlobalDefinition(GD);
1166     return;
1167   }
1168 
1169   // If we're deferring emission of a C++ variable with an
1170   // initializer, remember the order in which it appeared in the file.
1171   if (getLangOpts().CPlusPlus && isa<VarDecl>(Global) &&
1172       cast<VarDecl>(Global)->hasInit()) {
1173     DelayedCXXInitPosition[Global] = CXXGlobalInits.size();
1174     CXXGlobalInits.push_back(0);
1175   }
1176 
1177   // If the value has already been used, add it directly to the
1178   // DeferredDeclsToEmit list.
1179   StringRef MangledName = getMangledName(GD);
1180   if (GetGlobalValue(MangledName))
1181     DeferredDeclsToEmit.push_back(GD);
1182   else {
1183     // Otherwise, remember that we saw a deferred decl with this name.  The
1184     // first use of the mangled name will cause it to move into
1185     // DeferredDeclsToEmit.
1186     DeferredDecls[MangledName] = GD;
1187   }
1188 }
1189 
1190 namespace {
1191   struct FunctionIsDirectlyRecursive :
1192     public RecursiveASTVisitor<FunctionIsDirectlyRecursive> {
1193     const StringRef Name;
1194     const Builtin::Context &BI;
1195     bool Result;
1196     FunctionIsDirectlyRecursive(StringRef N, const Builtin::Context &C) :
1197       Name(N), BI(C), Result(false) {
1198     }
1199     typedef RecursiveASTVisitor<FunctionIsDirectlyRecursive> Base;
1200 
1201     bool TraverseCallExpr(CallExpr *E) {
1202       const FunctionDecl *FD = E->getDirectCallee();
1203       if (!FD)
1204         return true;
1205       AsmLabelAttr *Attr = FD->getAttr<AsmLabelAttr>();
1206       if (Attr && Name == Attr->getLabel()) {
1207         Result = true;
1208         return false;
1209       }
1210       unsigned BuiltinID = FD->getBuiltinID();
1211       if (!BuiltinID)
1212         return true;
1213       StringRef BuiltinName = BI.GetName(BuiltinID);
1214       if (BuiltinName.startswith("__builtin_") &&
1215           Name == BuiltinName.slice(strlen("__builtin_"), StringRef::npos)) {
1216         Result = true;
1217         return false;
1218       }
1219       return true;
1220     }
1221   };
1222 }
1223 
1224 // isTriviallyRecursive - Check if this function calls another
1225 // decl that, because of the asm attribute or the other decl being a builtin,
1226 // ends up pointing to itself.
1227 bool
1228 CodeGenModule::isTriviallyRecursive(const FunctionDecl *FD) {
1229   StringRef Name;
1230   if (getCXXABI().getMangleContext().shouldMangleDeclName(FD)) {
1231     // asm labels are a special kind of mangling we have to support.
1232     AsmLabelAttr *Attr = FD->getAttr<AsmLabelAttr>();
1233     if (!Attr)
1234       return false;
1235     Name = Attr->getLabel();
1236   } else {
1237     Name = FD->getName();
1238   }
1239 
1240   FunctionIsDirectlyRecursive Walker(Name, Context.BuiltinInfo);
1241   Walker.TraverseFunctionDecl(const_cast<FunctionDecl*>(FD));
1242   return Walker.Result;
1243 }
1244 
1245 bool
1246 CodeGenModule::shouldEmitFunction(GlobalDecl GD) {
1247   if (getFunctionLinkage(GD) != llvm::Function::AvailableExternallyLinkage)
1248     return true;
1249   const FunctionDecl *F = cast<FunctionDecl>(GD.getDecl());
1250   if (CodeGenOpts.OptimizationLevel == 0 &&
1251       !F->hasAttr<AlwaysInlineAttr>() && !F->hasAttr<ForceInlineAttr>())
1252     return false;
1253   // PR9614. Avoid cases where the source code is lying to us. An available
1254   // externally function should have an equivalent function somewhere else,
1255   // but a function that calls itself is clearly not equivalent to the real
1256   // implementation.
1257   // This happens in glibc's btowc and in some configure checks.
1258   return !isTriviallyRecursive(F);
1259 }
1260 
1261 /// If the type for the method's class was generated by
1262 /// CGDebugInfo::createContextChain(), the cache contains only a
1263 /// limited DIType without any declarations. Since EmitFunctionStart()
1264 /// needs to find the canonical declaration for each method, we need
1265 /// to construct the complete type prior to emitting the method.
1266 void CodeGenModule::CompleteDIClassType(const CXXMethodDecl* D) {
1267   if (!D->isInstance())
1268     return;
1269 
1270   if (CGDebugInfo *DI = getModuleDebugInfo())
1271     if (getCodeGenOpts().getDebugInfo() >= CodeGenOptions::LimitedDebugInfo) {
1272       const PointerType *ThisPtr =
1273         cast<PointerType>(D->getThisType(getContext()));
1274       DI->getOrCreateRecordType(ThisPtr->getPointeeType(), D->getLocation());
1275     }
1276 }
1277 
1278 void CodeGenModule::EmitGlobalDefinition(GlobalDecl GD) {
1279   const ValueDecl *D = cast<ValueDecl>(GD.getDecl());
1280 
1281   PrettyStackTraceDecl CrashInfo(const_cast<ValueDecl *>(D), D->getLocation(),
1282                                  Context.getSourceManager(),
1283                                  "Generating code for declaration");
1284 
1285   if (isa<FunctionDecl>(D)) {
1286     // At -O0, don't generate IR for functions with available_externally
1287     // linkage.
1288     if (!shouldEmitFunction(GD))
1289       return;
1290 
1291     if (const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(D)) {
1292       CompleteDIClassType(Method);
1293       // Make sure to emit the definition(s) before we emit the thunks.
1294       // This is necessary for the generation of certain thunks.
1295       if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(Method))
1296         EmitCXXConstructor(CD, GD.getCtorType());
1297       else if (const CXXDestructorDecl *DD =dyn_cast<CXXDestructorDecl>(Method))
1298         EmitCXXDestructor(DD, GD.getDtorType());
1299       else
1300         EmitGlobalFunctionDefinition(GD);
1301 
1302       if (Method->isVirtual())
1303         getVTables().EmitThunks(GD);
1304 
1305       return;
1306     }
1307 
1308     return EmitGlobalFunctionDefinition(GD);
1309   }
1310 
1311   if (const VarDecl *VD = dyn_cast<VarDecl>(D))
1312     return EmitGlobalVarDefinition(VD);
1313 
1314   llvm_unreachable("Invalid argument to EmitGlobalDefinition()");
1315 }
1316 
1317 /// GetOrCreateLLVMFunction - If the specified mangled name is not in the
1318 /// module, create and return an llvm Function with the specified type. If there
1319 /// is something in the module with the specified name, return it potentially
1320 /// bitcasted to the right type.
1321 ///
1322 /// If D is non-null, it specifies a decl that correspond to this.  This is used
1323 /// to set the attributes on the function when it is first created.
1324 llvm::Constant *
1325 CodeGenModule::GetOrCreateLLVMFunction(StringRef MangledName,
1326                                        llvm::Type *Ty,
1327                                        GlobalDecl D, bool ForVTable,
1328                                        llvm::AttributeSet ExtraAttrs) {
1329   // Lookup the entry, lazily creating it if necessary.
1330   llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
1331   if (Entry) {
1332     if (WeakRefReferences.erase(Entry)) {
1333       const FunctionDecl *FD = cast_or_null<FunctionDecl>(D.getDecl());
1334       if (FD && !FD->hasAttr<WeakAttr>())
1335         Entry->setLinkage(llvm::Function::ExternalLinkage);
1336     }
1337 
1338     if (Entry->getType()->getElementType() == Ty)
1339       return Entry;
1340 
1341     // Make sure the result is of the correct type.
1342     return llvm::ConstantExpr::getBitCast(Entry, Ty->getPointerTo());
1343   }
1344 
1345   // This function doesn't have a complete type (for example, the return
1346   // type is an incomplete struct). Use a fake type instead, and make
1347   // sure not to try to set attributes.
1348   bool IsIncompleteFunction = false;
1349 
1350   llvm::FunctionType *FTy;
1351   if (isa<llvm::FunctionType>(Ty)) {
1352     FTy = cast<llvm::FunctionType>(Ty);
1353   } else {
1354     FTy = llvm::FunctionType::get(VoidTy, false);
1355     IsIncompleteFunction = true;
1356   }
1357 
1358   llvm::Function *F = llvm::Function::Create(FTy,
1359                                              llvm::Function::ExternalLinkage,
1360                                              MangledName, &getModule());
1361   assert(F->getName() == MangledName && "name was uniqued!");
1362   if (D.getDecl())
1363     SetFunctionAttributes(D, F, IsIncompleteFunction);
1364   if (ExtraAttrs.hasAttributes(llvm::AttributeSet::FunctionIndex)) {
1365     llvm::AttrBuilder B(ExtraAttrs, llvm::AttributeSet::FunctionIndex);
1366     F->addAttributes(llvm::AttributeSet::FunctionIndex,
1367                      llvm::AttributeSet::get(VMContext,
1368                                              llvm::AttributeSet::FunctionIndex,
1369                                              B));
1370   }
1371 
1372   // This is the first use or definition of a mangled name.  If there is a
1373   // deferred decl with this name, remember that we need to emit it at the end
1374   // of the file.
1375   llvm::StringMap<GlobalDecl>::iterator DDI = DeferredDecls.find(MangledName);
1376   if (DDI != DeferredDecls.end()) {
1377     // Move the potentially referenced deferred decl to the DeferredDeclsToEmit
1378     // list, and remove it from DeferredDecls (since we don't need it anymore).
1379     DeferredDeclsToEmit.push_back(DDI->second);
1380     DeferredDecls.erase(DDI);
1381 
1382   // Otherwise, there are cases we have to worry about where we're
1383   // using a declaration for which we must emit a definition but where
1384   // we might not find a top-level definition:
1385   //   - member functions defined inline in their classes
1386   //   - friend functions defined inline in some class
1387   //   - special member functions with implicit definitions
1388   // If we ever change our AST traversal to walk into class methods,
1389   // this will be unnecessary.
1390   //
1391   // We also don't emit a definition for a function if it's going to be an entry
1392   // in a vtable, unless it's already marked as used.
1393   } else if (getLangOpts().CPlusPlus && D.getDecl()) {
1394     // Look for a declaration that's lexically in a record.
1395     const FunctionDecl *FD = cast<FunctionDecl>(D.getDecl());
1396     FD = FD->getMostRecentDecl();
1397     do {
1398       if (isa<CXXRecordDecl>(FD->getLexicalDeclContext())) {
1399         if (FD->isImplicit() && !ForVTable) {
1400           assert(FD->isUsed() && "Sema didn't mark implicit function as used!");
1401           DeferredDeclsToEmit.push_back(D.getWithDecl(FD));
1402           break;
1403         } else if (FD->doesThisDeclarationHaveABody()) {
1404           DeferredDeclsToEmit.push_back(D.getWithDecl(FD));
1405           break;
1406         }
1407       }
1408       FD = FD->getPreviousDecl();
1409     } while (FD);
1410   }
1411 
1412   // Make sure the result is of the requested type.
1413   if (!IsIncompleteFunction) {
1414     assert(F->getType()->getElementType() == Ty);
1415     return F;
1416   }
1417 
1418   llvm::Type *PTy = llvm::PointerType::getUnqual(Ty);
1419   return llvm::ConstantExpr::getBitCast(F, PTy);
1420 }
1421 
1422 /// GetAddrOfFunction - Return the address of the given function.  If Ty is
1423 /// non-null, then this function will use the specified type if it has to
1424 /// create it (this occurs when we see a definition of the function).
1425 llvm::Constant *CodeGenModule::GetAddrOfFunction(GlobalDecl GD,
1426                                                  llvm::Type *Ty,
1427                                                  bool ForVTable) {
1428   // If there was no specific requested type, just convert it now.
1429   if (!Ty)
1430     Ty = getTypes().ConvertType(cast<ValueDecl>(GD.getDecl())->getType());
1431 
1432   StringRef MangledName = getMangledName(GD);
1433   return GetOrCreateLLVMFunction(MangledName, Ty, GD, ForVTable);
1434 }
1435 
1436 /// CreateRuntimeFunction - Create a new runtime function with the specified
1437 /// type and name.
1438 llvm::Constant *
1439 CodeGenModule::CreateRuntimeFunction(llvm::FunctionType *FTy,
1440                                      StringRef Name,
1441                                      llvm::AttributeSet ExtraAttrs) {
1442   llvm::Constant *C
1443     = GetOrCreateLLVMFunction(Name, FTy, GlobalDecl(), /*ForVTable=*/false,
1444                               ExtraAttrs);
1445   if (llvm::Function *F = dyn_cast<llvm::Function>(C))
1446     if (F->empty())
1447       F->setCallingConv(getRuntimeCC());
1448   return C;
1449 }
1450 
1451 /// isTypeConstant - Determine whether an object of this type can be emitted
1452 /// as a constant.
1453 ///
1454 /// If ExcludeCtor is true, the duration when the object's constructor runs
1455 /// will not be considered. The caller will need to verify that the object is
1456 /// not written to during its construction.
1457 bool CodeGenModule::isTypeConstant(QualType Ty, bool ExcludeCtor) {
1458   if (!Ty.isConstant(Context) && !Ty->isReferenceType())
1459     return false;
1460 
1461   if (Context.getLangOpts().CPlusPlus) {
1462     if (const CXXRecordDecl *Record
1463           = Context.getBaseElementType(Ty)->getAsCXXRecordDecl())
1464       return ExcludeCtor && !Record->hasMutableFields() &&
1465              Record->hasTrivialDestructor();
1466   }
1467 
1468   return true;
1469 }
1470 
1471 /// GetOrCreateLLVMGlobal - If the specified mangled name is not in the module,
1472 /// create and return an llvm GlobalVariable with the specified type.  If there
1473 /// is something in the module with the specified name, return it potentially
1474 /// bitcasted to the right type.
1475 ///
1476 /// If D is non-null, it specifies a decl that correspond to this.  This is used
1477 /// to set the attributes on the global when it is first created.
1478 llvm::Constant *
1479 CodeGenModule::GetOrCreateLLVMGlobal(StringRef MangledName,
1480                                      llvm::PointerType *Ty,
1481                                      const VarDecl *D,
1482                                      bool UnnamedAddr) {
1483   // Lookup the entry, lazily creating it if necessary.
1484   llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
1485   if (Entry) {
1486     if (WeakRefReferences.erase(Entry)) {
1487       if (D && !D->hasAttr<WeakAttr>())
1488         Entry->setLinkage(llvm::Function::ExternalLinkage);
1489     }
1490 
1491     if (UnnamedAddr)
1492       Entry->setUnnamedAddr(true);
1493 
1494     if (Entry->getType() == Ty)
1495       return Entry;
1496 
1497     // Make sure the result is of the correct type.
1498     return llvm::ConstantExpr::getBitCast(Entry, Ty);
1499   }
1500 
1501   // This is the first use or definition of a mangled name.  If there is a
1502   // deferred decl with this name, remember that we need to emit it at the end
1503   // of the file.
1504   llvm::StringMap<GlobalDecl>::iterator DDI = DeferredDecls.find(MangledName);
1505   if (DDI != DeferredDecls.end()) {
1506     // Move the potentially referenced deferred decl to the DeferredDeclsToEmit
1507     // list, and remove it from DeferredDecls (since we don't need it anymore).
1508     DeferredDeclsToEmit.push_back(DDI->second);
1509     DeferredDecls.erase(DDI);
1510   }
1511 
1512   unsigned AddrSpace = GetGlobalVarAddressSpace(D, Ty->getAddressSpace());
1513   llvm::GlobalVariable *GV =
1514     new llvm::GlobalVariable(getModule(), Ty->getElementType(), false,
1515                              llvm::GlobalValue::ExternalLinkage,
1516                              0, MangledName, 0,
1517                              llvm::GlobalVariable::NotThreadLocal, AddrSpace);
1518 
1519   // Handle things which are present even on external declarations.
1520   if (D) {
1521     // FIXME: This code is overly simple and should be merged with other global
1522     // handling.
1523     GV->setConstant(isTypeConstant(D->getType(), false));
1524 
1525     // Set linkage and visibility in case we never see a definition.
1526     LinkageInfo LV = D->getLinkageAndVisibility();
1527     if (LV.getLinkage() != ExternalLinkage) {
1528       // Don't set internal linkage on declarations.
1529     } else {
1530       if (D->hasAttr<DLLImportAttr>())
1531         GV->setLinkage(llvm::GlobalValue::DLLImportLinkage);
1532       else if (D->hasAttr<WeakAttr>() || D->isWeakImported())
1533         GV->setLinkage(llvm::GlobalValue::ExternalWeakLinkage);
1534 
1535       // Set visibility on a declaration only if it's explicit.
1536       if (LV.isVisibilityExplicit())
1537         GV->setVisibility(GetLLVMVisibility(LV.getVisibility()));
1538     }
1539 
1540     if (D->getTLSKind()) {
1541       if (D->getTLSKind() == VarDecl::TLS_Dynamic)
1542         CXXThreadLocals.push_back(std::make_pair(D, GV));
1543       setTLSMode(GV, *D);
1544     }
1545   }
1546 
1547   if (AddrSpace != Ty->getAddressSpace())
1548     return llvm::ConstantExpr::getBitCast(GV, Ty);
1549   else
1550     return GV;
1551 }
1552 
1553 
1554 llvm::GlobalVariable *
1555 CodeGenModule::CreateOrReplaceCXXRuntimeVariable(StringRef Name,
1556                                       llvm::Type *Ty,
1557                                       llvm::GlobalValue::LinkageTypes Linkage) {
1558   llvm::GlobalVariable *GV = getModule().getNamedGlobal(Name);
1559   llvm::GlobalVariable *OldGV = 0;
1560 
1561 
1562   if (GV) {
1563     // Check if the variable has the right type.
1564     if (GV->getType()->getElementType() == Ty)
1565       return GV;
1566 
1567     // Because C++ name mangling, the only way we can end up with an already
1568     // existing global with the same name is if it has been declared extern "C".
1569     assert(GV->isDeclaration() && "Declaration has wrong type!");
1570     OldGV = GV;
1571   }
1572 
1573   // Create a new variable.
1574   GV = new llvm::GlobalVariable(getModule(), Ty, /*isConstant=*/true,
1575                                 Linkage, 0, Name);
1576 
1577   if (OldGV) {
1578     // Replace occurrences of the old variable if needed.
1579     GV->takeName(OldGV);
1580 
1581     if (!OldGV->use_empty()) {
1582       llvm::Constant *NewPtrForOldDecl =
1583       llvm::ConstantExpr::getBitCast(GV, OldGV->getType());
1584       OldGV->replaceAllUsesWith(NewPtrForOldDecl);
1585     }
1586 
1587     OldGV->eraseFromParent();
1588   }
1589 
1590   return GV;
1591 }
1592 
1593 /// GetAddrOfGlobalVar - Return the llvm::Constant for the address of the
1594 /// given global variable.  If Ty is non-null and if the global doesn't exist,
1595 /// then it will be created with the specified type instead of whatever the
1596 /// normal requested type would be.
1597 llvm::Constant *CodeGenModule::GetAddrOfGlobalVar(const VarDecl *D,
1598                                                   llvm::Type *Ty) {
1599   assert(D->hasGlobalStorage() && "Not a global variable");
1600   QualType ASTTy = D->getType();
1601   if (Ty == 0)
1602     Ty = getTypes().ConvertTypeForMem(ASTTy);
1603 
1604   llvm::PointerType *PTy =
1605     llvm::PointerType::get(Ty, getContext().getTargetAddressSpace(ASTTy));
1606 
1607   StringRef MangledName = getMangledName(D);
1608   return GetOrCreateLLVMGlobal(MangledName, PTy, D);
1609 }
1610 
1611 /// CreateRuntimeVariable - Create a new runtime global variable with the
1612 /// specified type and name.
1613 llvm::Constant *
1614 CodeGenModule::CreateRuntimeVariable(llvm::Type *Ty,
1615                                      StringRef Name) {
1616   return GetOrCreateLLVMGlobal(Name, llvm::PointerType::getUnqual(Ty), 0,
1617                                true);
1618 }
1619 
1620 void CodeGenModule::EmitTentativeDefinition(const VarDecl *D) {
1621   assert(!D->getInit() && "Cannot emit definite definitions here!");
1622 
1623   if (MayDeferGeneration(D)) {
1624     // If we have not seen a reference to this variable yet, place it
1625     // into the deferred declarations table to be emitted if needed
1626     // later.
1627     StringRef MangledName = getMangledName(D);
1628     if (!GetGlobalValue(MangledName)) {
1629       DeferredDecls[MangledName] = D;
1630       return;
1631     }
1632   }
1633 
1634   // The tentative definition is the only definition.
1635   EmitGlobalVarDefinition(D);
1636 }
1637 
1638 CharUnits CodeGenModule::GetTargetTypeStoreSize(llvm::Type *Ty) const {
1639     return Context.toCharUnitsFromBits(
1640       TheDataLayout.getTypeStoreSizeInBits(Ty));
1641 }
1642 
1643 unsigned CodeGenModule::GetGlobalVarAddressSpace(const VarDecl *D,
1644                                                  unsigned AddrSpace) {
1645   if (LangOpts.CUDA && CodeGenOpts.CUDAIsDevice) {
1646     if (D->hasAttr<CUDAConstantAttr>())
1647       AddrSpace = getContext().getTargetAddressSpace(LangAS::cuda_constant);
1648     else if (D->hasAttr<CUDASharedAttr>())
1649       AddrSpace = getContext().getTargetAddressSpace(LangAS::cuda_shared);
1650     else
1651       AddrSpace = getContext().getTargetAddressSpace(LangAS::cuda_device);
1652   }
1653 
1654   return AddrSpace;
1655 }
1656 
1657 template<typename SomeDecl>
1658 void CodeGenModule::MaybeHandleStaticInExternC(const SomeDecl *D,
1659                                                llvm::GlobalValue *GV) {
1660   if (!getLangOpts().CPlusPlus)
1661     return;
1662 
1663   // Must have 'used' attribute, or else inline assembly can't rely on
1664   // the name existing.
1665   if (!D->template hasAttr<UsedAttr>())
1666     return;
1667 
1668   // Must have internal linkage and an ordinary name.
1669   if (!D->getIdentifier() || D->getFormalLinkage() != InternalLinkage)
1670     return;
1671 
1672   // Must be in an extern "C" context. Entities declared directly within
1673   // a record are not extern "C" even if the record is in such a context.
1674   const SomeDecl *First = D->getFirstDeclaration();
1675   if (First->getDeclContext()->isRecord() || !First->isInExternCContext())
1676     return;
1677 
1678   // OK, this is an internal linkage entity inside an extern "C" linkage
1679   // specification. Make a note of that so we can give it the "expected"
1680   // mangled name if nothing else is using that name.
1681   std::pair<StaticExternCMap::iterator, bool> R =
1682       StaticExternCValues.insert(std::make_pair(D->getIdentifier(), GV));
1683 
1684   // If we have multiple internal linkage entities with the same name
1685   // in extern "C" regions, none of them gets that name.
1686   if (!R.second)
1687     R.first->second = 0;
1688 }
1689 
1690 void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D) {
1691   llvm::Constant *Init = 0;
1692   QualType ASTTy = D->getType();
1693   CXXRecordDecl *RD = ASTTy->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
1694   bool NeedsGlobalCtor = false;
1695   bool NeedsGlobalDtor = RD && !RD->hasTrivialDestructor();
1696 
1697   const VarDecl *InitDecl;
1698   const Expr *InitExpr = D->getAnyInitializer(InitDecl);
1699 
1700   if (!InitExpr) {
1701     // This is a tentative definition; tentative definitions are
1702     // implicitly initialized with { 0 }.
1703     //
1704     // Note that tentative definitions are only emitted at the end of
1705     // a translation unit, so they should never have incomplete
1706     // type. In addition, EmitTentativeDefinition makes sure that we
1707     // never attempt to emit a tentative definition if a real one
1708     // exists. A use may still exists, however, so we still may need
1709     // to do a RAUW.
1710     assert(!ASTTy->isIncompleteType() && "Unexpected incomplete type");
1711     Init = EmitNullConstant(D->getType());
1712   } else {
1713     initializedGlobalDecl = GlobalDecl(D);
1714     Init = EmitConstantInit(*InitDecl);
1715 
1716     if (!Init) {
1717       QualType T = InitExpr->getType();
1718       if (D->getType()->isReferenceType())
1719         T = D->getType();
1720 
1721       if (getLangOpts().CPlusPlus) {
1722         Init = EmitNullConstant(T);
1723         NeedsGlobalCtor = true;
1724       } else {
1725         ErrorUnsupported(D, "static initializer");
1726         Init = llvm::UndefValue::get(getTypes().ConvertType(T));
1727       }
1728     } else {
1729       // We don't need an initializer, so remove the entry for the delayed
1730       // initializer position (just in case this entry was delayed) if we
1731       // also don't need to register a destructor.
1732       if (getLangOpts().CPlusPlus && !NeedsGlobalDtor)
1733         DelayedCXXInitPosition.erase(D);
1734     }
1735   }
1736 
1737   llvm::Type* InitType = Init->getType();
1738   llvm::Constant *Entry = GetAddrOfGlobalVar(D, InitType);
1739 
1740   // Strip off a bitcast if we got one back.
1741   if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(Entry)) {
1742     assert(CE->getOpcode() == llvm::Instruction::BitCast ||
1743            // all zero index gep.
1744            CE->getOpcode() == llvm::Instruction::GetElementPtr);
1745     Entry = CE->getOperand(0);
1746   }
1747 
1748   // Entry is now either a Function or GlobalVariable.
1749   llvm::GlobalVariable *GV = dyn_cast<llvm::GlobalVariable>(Entry);
1750 
1751   // We have a definition after a declaration with the wrong type.
1752   // We must make a new GlobalVariable* and update everything that used OldGV
1753   // (a declaration or tentative definition) with the new GlobalVariable*
1754   // (which will be a definition).
1755   //
1756   // This happens if there is a prototype for a global (e.g.
1757   // "extern int x[];") and then a definition of a different type (e.g.
1758   // "int x[10];"). This also happens when an initializer has a different type
1759   // from the type of the global (this happens with unions).
1760   if (GV == 0 ||
1761       GV->getType()->getElementType() != InitType ||
1762       GV->getType()->getAddressSpace() !=
1763        GetGlobalVarAddressSpace(D, getContext().getTargetAddressSpace(ASTTy))) {
1764 
1765     // Move the old entry aside so that we'll create a new one.
1766     Entry->setName(StringRef());
1767 
1768     // Make a new global with the correct type, this is now guaranteed to work.
1769     GV = cast<llvm::GlobalVariable>(GetAddrOfGlobalVar(D, InitType));
1770 
1771     // Replace all uses of the old global with the new global
1772     llvm::Constant *NewPtrForOldDecl =
1773         llvm::ConstantExpr::getBitCast(GV, Entry->getType());
1774     Entry->replaceAllUsesWith(NewPtrForOldDecl);
1775 
1776     // Erase the old global, since it is no longer used.
1777     cast<llvm::GlobalValue>(Entry)->eraseFromParent();
1778   }
1779 
1780   MaybeHandleStaticInExternC(D, GV);
1781 
1782   if (D->hasAttr<AnnotateAttr>())
1783     AddGlobalAnnotations(D, GV);
1784 
1785   GV->setInitializer(Init);
1786 
1787   // If it is safe to mark the global 'constant', do so now.
1788   GV->setConstant(!NeedsGlobalCtor && !NeedsGlobalDtor &&
1789                   isTypeConstant(D->getType(), true));
1790 
1791   GV->setAlignment(getContext().getDeclAlign(D).getQuantity());
1792 
1793   // Set the llvm linkage type as appropriate.
1794   llvm::GlobalValue::LinkageTypes Linkage =
1795     GetLLVMLinkageVarDefinition(D, GV);
1796   GV->setLinkage(Linkage);
1797   if (Linkage == llvm::GlobalVariable::CommonLinkage)
1798     // common vars aren't constant even if declared const.
1799     GV->setConstant(false);
1800 
1801   SetCommonAttributes(D, GV);
1802 
1803   // Emit the initializer function if necessary.
1804   if (NeedsGlobalCtor || NeedsGlobalDtor)
1805     EmitCXXGlobalVarDeclInitFunc(D, GV, NeedsGlobalCtor);
1806 
1807   // If we are compiling with ASan, add metadata indicating dynamically
1808   // initialized globals.
1809   if (SanOpts.Address && NeedsGlobalCtor) {
1810     llvm::Module &M = getModule();
1811 
1812     llvm::NamedMDNode *DynamicInitializers =
1813         M.getOrInsertNamedMetadata("llvm.asan.dynamically_initialized_globals");
1814     llvm::Value *GlobalToAdd[] = { GV };
1815     llvm::MDNode *ThisGlobal = llvm::MDNode::get(VMContext, GlobalToAdd);
1816     DynamicInitializers->addOperand(ThisGlobal);
1817   }
1818 
1819   // Emit global variable debug information.
1820   if (CGDebugInfo *DI = getModuleDebugInfo())
1821     if (getCodeGenOpts().getDebugInfo() >= CodeGenOptions::LimitedDebugInfo)
1822       DI->EmitGlobalVariable(GV, D);
1823 }
1824 
1825 llvm::GlobalValue::LinkageTypes
1826 CodeGenModule::GetLLVMLinkageVarDefinition(const VarDecl *D,
1827                                            llvm::GlobalVariable *GV) {
1828   GVALinkage Linkage = getContext().GetGVALinkageForVariable(D);
1829   if (Linkage == GVA_Internal)
1830     return llvm::Function::InternalLinkage;
1831   else if (D->hasAttr<DLLImportAttr>())
1832     return llvm::Function::DLLImportLinkage;
1833   else if (D->hasAttr<DLLExportAttr>())
1834     return llvm::Function::DLLExportLinkage;
1835   else if (D->hasAttr<SelectAnyAttr>()) {
1836     // selectany symbols are externally visible, so use weak instead of
1837     // linkonce.  MSVC optimizes away references to const selectany globals, so
1838     // all definitions should be the same and ODR linkage should be used.
1839     // http://msdn.microsoft.com/en-us/library/5tkz6s71.aspx
1840     return llvm::GlobalVariable::WeakODRLinkage;
1841   } else if (D->hasAttr<WeakAttr>()) {
1842     if (GV->isConstant())
1843       return llvm::GlobalVariable::WeakODRLinkage;
1844     else
1845       return llvm::GlobalVariable::WeakAnyLinkage;
1846   } else if (Linkage == GVA_TemplateInstantiation ||
1847              Linkage == GVA_ExplicitTemplateInstantiation)
1848     return llvm::GlobalVariable::WeakODRLinkage;
1849   else if (!getLangOpts().CPlusPlus &&
1850            ((!CodeGenOpts.NoCommon && !D->getAttr<NoCommonAttr>()) ||
1851              D->getAttr<CommonAttr>()) &&
1852            !D->hasExternalStorage() && !D->getInit() &&
1853            !D->getAttr<SectionAttr>() && !D->getTLSKind() &&
1854            !D->getAttr<WeakImportAttr>()) {
1855     // Thread local vars aren't considered common linkage.
1856     return llvm::GlobalVariable::CommonLinkage;
1857   } else if (D->getTLSKind() == VarDecl::TLS_Dynamic &&
1858              getTarget().getTriple().isMacOSX())
1859     // On Darwin, the backing variable for a C++11 thread_local variable always
1860     // has internal linkage; all accesses should just be calls to the
1861     // Itanium-specified entry point, which has the normal linkage of the
1862     // variable.
1863     return llvm::GlobalValue::InternalLinkage;
1864   return llvm::GlobalVariable::ExternalLinkage;
1865 }
1866 
1867 /// Replace the uses of a function that was declared with a non-proto type.
1868 /// We want to silently drop extra arguments from call sites
1869 static void replaceUsesOfNonProtoConstant(llvm::Constant *old,
1870                                           llvm::Function *newFn) {
1871   // Fast path.
1872   if (old->use_empty()) return;
1873 
1874   llvm::Type *newRetTy = newFn->getReturnType();
1875   SmallVector<llvm::Value*, 4> newArgs;
1876 
1877   for (llvm::Value::use_iterator ui = old->use_begin(), ue = old->use_end();
1878          ui != ue; ) {
1879     llvm::Value::use_iterator use = ui++; // Increment before the use is erased.
1880     llvm::User *user = *use;
1881 
1882     // Recognize and replace uses of bitcasts.  Most calls to
1883     // unprototyped functions will use bitcasts.
1884     if (llvm::ConstantExpr *bitcast = dyn_cast<llvm::ConstantExpr>(user)) {
1885       if (bitcast->getOpcode() == llvm::Instruction::BitCast)
1886         replaceUsesOfNonProtoConstant(bitcast, newFn);
1887       continue;
1888     }
1889 
1890     // Recognize calls to the function.
1891     llvm::CallSite callSite(user);
1892     if (!callSite) continue;
1893     if (!callSite.isCallee(use)) continue;
1894 
1895     // If the return types don't match exactly, then we can't
1896     // transform this call unless it's dead.
1897     if (callSite->getType() != newRetTy && !callSite->use_empty())
1898       continue;
1899 
1900     // Get the call site's attribute list.
1901     SmallVector<llvm::AttributeSet, 8> newAttrs;
1902     llvm::AttributeSet oldAttrs = callSite.getAttributes();
1903 
1904     // Collect any return attributes from the call.
1905     if (oldAttrs.hasAttributes(llvm::AttributeSet::ReturnIndex))
1906       newAttrs.push_back(
1907         llvm::AttributeSet::get(newFn->getContext(),
1908                                 oldAttrs.getRetAttributes()));
1909 
1910     // If the function was passed too few arguments, don't transform.
1911     unsigned newNumArgs = newFn->arg_size();
1912     if (callSite.arg_size() < newNumArgs) continue;
1913 
1914     // If extra arguments were passed, we silently drop them.
1915     // If any of the types mismatch, we don't transform.
1916     unsigned argNo = 0;
1917     bool dontTransform = false;
1918     for (llvm::Function::arg_iterator ai = newFn->arg_begin(),
1919            ae = newFn->arg_end(); ai != ae; ++ai, ++argNo) {
1920       if (callSite.getArgument(argNo)->getType() != ai->getType()) {
1921         dontTransform = true;
1922         break;
1923       }
1924 
1925       // Add any parameter attributes.
1926       if (oldAttrs.hasAttributes(argNo + 1))
1927         newAttrs.
1928           push_back(llvm::
1929                     AttributeSet::get(newFn->getContext(),
1930                                       oldAttrs.getParamAttributes(argNo + 1)));
1931     }
1932     if (dontTransform)
1933       continue;
1934 
1935     if (oldAttrs.hasAttributes(llvm::AttributeSet::FunctionIndex))
1936       newAttrs.push_back(llvm::AttributeSet::get(newFn->getContext(),
1937                                                  oldAttrs.getFnAttributes()));
1938 
1939     // Okay, we can transform this.  Create the new call instruction and copy
1940     // over the required information.
1941     newArgs.append(callSite.arg_begin(), callSite.arg_begin() + argNo);
1942 
1943     llvm::CallSite newCall;
1944     if (callSite.isCall()) {
1945       newCall = llvm::CallInst::Create(newFn, newArgs, "",
1946                                        callSite.getInstruction());
1947     } else {
1948       llvm::InvokeInst *oldInvoke =
1949         cast<llvm::InvokeInst>(callSite.getInstruction());
1950       newCall = llvm::InvokeInst::Create(newFn,
1951                                          oldInvoke->getNormalDest(),
1952                                          oldInvoke->getUnwindDest(),
1953                                          newArgs, "",
1954                                          callSite.getInstruction());
1955     }
1956     newArgs.clear(); // for the next iteration
1957 
1958     if (!newCall->getType()->isVoidTy())
1959       newCall->takeName(callSite.getInstruction());
1960     newCall.setAttributes(
1961                      llvm::AttributeSet::get(newFn->getContext(), newAttrs));
1962     newCall.setCallingConv(callSite.getCallingConv());
1963 
1964     // Finally, remove the old call, replacing any uses with the new one.
1965     if (!callSite->use_empty())
1966       callSite->replaceAllUsesWith(newCall.getInstruction());
1967 
1968     // Copy debug location attached to CI.
1969     if (!callSite->getDebugLoc().isUnknown())
1970       newCall->setDebugLoc(callSite->getDebugLoc());
1971     callSite->eraseFromParent();
1972   }
1973 }
1974 
1975 /// ReplaceUsesOfNonProtoTypeWithRealFunction - This function is called when we
1976 /// implement a function with no prototype, e.g. "int foo() {}".  If there are
1977 /// existing call uses of the old function in the module, this adjusts them to
1978 /// call the new function directly.
1979 ///
1980 /// This is not just a cleanup: the always_inline pass requires direct calls to
1981 /// functions to be able to inline them.  If there is a bitcast in the way, it
1982 /// won't inline them.  Instcombine normally deletes these calls, but it isn't
1983 /// run at -O0.
1984 static void ReplaceUsesOfNonProtoTypeWithRealFunction(llvm::GlobalValue *Old,
1985                                                       llvm::Function *NewFn) {
1986   // If we're redefining a global as a function, don't transform it.
1987   if (!isa<llvm::Function>(Old)) return;
1988 
1989   replaceUsesOfNonProtoConstant(Old, NewFn);
1990 }
1991 
1992 void CodeGenModule::HandleCXXStaticMemberVarInstantiation(VarDecl *VD) {
1993   TemplateSpecializationKind TSK = VD->getTemplateSpecializationKind();
1994   // If we have a definition, this might be a deferred decl. If the
1995   // instantiation is explicit, make sure we emit it at the end.
1996   if (VD->getDefinition() && TSK == TSK_ExplicitInstantiationDefinition)
1997     GetAddrOfGlobalVar(VD);
1998 
1999   EmitTopLevelDecl(VD);
2000 }
2001 
2002 void CodeGenModule::EmitGlobalFunctionDefinition(GlobalDecl GD) {
2003   const FunctionDecl *D = cast<FunctionDecl>(GD.getDecl());
2004 
2005   // Compute the function info and LLVM type.
2006   const CGFunctionInfo &FI = getTypes().arrangeGlobalDeclaration(GD);
2007   llvm::FunctionType *Ty = getTypes().GetFunctionType(FI);
2008 
2009   // Get or create the prototype for the function.
2010   llvm::Constant *Entry = GetAddrOfFunction(GD, Ty);
2011 
2012   // Strip off a bitcast if we got one back.
2013   if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(Entry)) {
2014     assert(CE->getOpcode() == llvm::Instruction::BitCast);
2015     Entry = CE->getOperand(0);
2016   }
2017 
2018 
2019   if (cast<llvm::GlobalValue>(Entry)->getType()->getElementType() != Ty) {
2020     llvm::GlobalValue *OldFn = cast<llvm::GlobalValue>(Entry);
2021 
2022     // If the types mismatch then we have to rewrite the definition.
2023     assert(OldFn->isDeclaration() &&
2024            "Shouldn't replace non-declaration");
2025 
2026     // F is the Function* for the one with the wrong type, we must make a new
2027     // Function* and update everything that used F (a declaration) with the new
2028     // Function* (which will be a definition).
2029     //
2030     // This happens if there is a prototype for a function
2031     // (e.g. "int f()") and then a definition of a different type
2032     // (e.g. "int f(int x)").  Move the old function aside so that it
2033     // doesn't interfere with GetAddrOfFunction.
2034     OldFn->setName(StringRef());
2035     llvm::Function *NewFn = cast<llvm::Function>(GetAddrOfFunction(GD, Ty));
2036 
2037     // This might be an implementation of a function without a
2038     // prototype, in which case, try to do special replacement of
2039     // calls which match the new prototype.  The really key thing here
2040     // is that we also potentially drop arguments from the call site
2041     // so as to make a direct call, which makes the inliner happier
2042     // and suppresses a number of optimizer warnings (!) about
2043     // dropping arguments.
2044     if (!OldFn->use_empty()) {
2045       ReplaceUsesOfNonProtoTypeWithRealFunction(OldFn, NewFn);
2046       OldFn->removeDeadConstantUsers();
2047     }
2048 
2049     // Replace uses of F with the Function we will endow with a body.
2050     if (!Entry->use_empty()) {
2051       llvm::Constant *NewPtrForOldDecl =
2052         llvm::ConstantExpr::getBitCast(NewFn, Entry->getType());
2053       Entry->replaceAllUsesWith(NewPtrForOldDecl);
2054     }
2055 
2056     // Ok, delete the old function now, which is dead.
2057     OldFn->eraseFromParent();
2058 
2059     Entry = NewFn;
2060   }
2061 
2062   // We need to set linkage and visibility on the function before
2063   // generating code for it because various parts of IR generation
2064   // want to propagate this information down (e.g. to local static
2065   // declarations).
2066   llvm::Function *Fn = cast<llvm::Function>(Entry);
2067   setFunctionLinkage(GD, Fn);
2068 
2069   // FIXME: this is redundant with part of SetFunctionDefinitionAttributes
2070   setGlobalVisibility(Fn, D);
2071 
2072   MaybeHandleStaticInExternC(D, Fn);
2073 
2074   CodeGenFunction(*this).GenerateCode(D, Fn, FI);
2075 
2076   SetFunctionDefinitionAttributes(D, Fn);
2077   SetLLVMFunctionAttributesForDefinition(D, Fn);
2078 
2079   if (const ConstructorAttr *CA = D->getAttr<ConstructorAttr>())
2080     AddGlobalCtor(Fn, CA->getPriority());
2081   if (const DestructorAttr *DA = D->getAttr<DestructorAttr>())
2082     AddGlobalDtor(Fn, DA->getPriority());
2083   if (D->hasAttr<AnnotateAttr>())
2084     AddGlobalAnnotations(D, Fn);
2085 }
2086 
2087 void CodeGenModule::EmitAliasDefinition(GlobalDecl GD) {
2088   const ValueDecl *D = cast<ValueDecl>(GD.getDecl());
2089   const AliasAttr *AA = D->getAttr<AliasAttr>();
2090   assert(AA && "Not an alias?");
2091 
2092   StringRef MangledName = getMangledName(GD);
2093 
2094   // If there is a definition in the module, then it wins over the alias.
2095   // This is dubious, but allow it to be safe.  Just ignore the alias.
2096   llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
2097   if (Entry && !Entry->isDeclaration())
2098     return;
2099 
2100   llvm::Type *DeclTy = getTypes().ConvertTypeForMem(D->getType());
2101 
2102   // Create a reference to the named value.  This ensures that it is emitted
2103   // if a deferred decl.
2104   llvm::Constant *Aliasee;
2105   if (isa<llvm::FunctionType>(DeclTy))
2106     Aliasee = GetOrCreateLLVMFunction(AA->getAliasee(), DeclTy, GD,
2107                                       /*ForVTable=*/false);
2108   else
2109     Aliasee = GetOrCreateLLVMGlobal(AA->getAliasee(),
2110                                     llvm::PointerType::getUnqual(DeclTy), 0);
2111 
2112   // Create the new alias itself, but don't set a name yet.
2113   llvm::GlobalValue *GA =
2114     new llvm::GlobalAlias(Aliasee->getType(),
2115                           llvm::Function::ExternalLinkage,
2116                           "", Aliasee, &getModule());
2117 
2118   if (Entry) {
2119     assert(Entry->isDeclaration());
2120 
2121     // If there is a declaration in the module, then we had an extern followed
2122     // by the alias, as in:
2123     //   extern int test6();
2124     //   ...
2125     //   int test6() __attribute__((alias("test7")));
2126     //
2127     // Remove it and replace uses of it with the alias.
2128     GA->takeName(Entry);
2129 
2130     Entry->replaceAllUsesWith(llvm::ConstantExpr::getBitCast(GA,
2131                                                           Entry->getType()));
2132     Entry->eraseFromParent();
2133   } else {
2134     GA->setName(MangledName);
2135   }
2136 
2137   // Set attributes which are particular to an alias; this is a
2138   // specialization of the attributes which may be set on a global
2139   // variable/function.
2140   if (D->hasAttr<DLLExportAttr>()) {
2141     if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
2142       // The dllexport attribute is ignored for undefined symbols.
2143       if (FD->hasBody())
2144         GA->setLinkage(llvm::Function::DLLExportLinkage);
2145     } else {
2146       GA->setLinkage(llvm::Function::DLLExportLinkage);
2147     }
2148   } else if (D->hasAttr<WeakAttr>() ||
2149              D->hasAttr<WeakRefAttr>() ||
2150              D->isWeakImported()) {
2151     GA->setLinkage(llvm::Function::WeakAnyLinkage);
2152   }
2153 
2154   SetCommonAttributes(D, GA);
2155 }
2156 
2157 llvm::Function *CodeGenModule::getIntrinsic(unsigned IID,
2158                                             ArrayRef<llvm::Type*> Tys) {
2159   return llvm::Intrinsic::getDeclaration(&getModule(), (llvm::Intrinsic::ID)IID,
2160                                          Tys);
2161 }
2162 
2163 static llvm::StringMapEntry<llvm::Constant*> &
2164 GetConstantCFStringEntry(llvm::StringMap<llvm::Constant*> &Map,
2165                          const StringLiteral *Literal,
2166                          bool TargetIsLSB,
2167                          bool &IsUTF16,
2168                          unsigned &StringLength) {
2169   StringRef String = Literal->getString();
2170   unsigned NumBytes = String.size();
2171 
2172   // Check for simple case.
2173   if (!Literal->containsNonAsciiOrNull()) {
2174     StringLength = NumBytes;
2175     return Map.GetOrCreateValue(String);
2176   }
2177 
2178   // Otherwise, convert the UTF8 literals into a string of shorts.
2179   IsUTF16 = true;
2180 
2181   SmallVector<UTF16, 128> ToBuf(NumBytes + 1); // +1 for ending nulls.
2182   const UTF8 *FromPtr = (const UTF8 *)String.data();
2183   UTF16 *ToPtr = &ToBuf[0];
2184 
2185   (void)ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes,
2186                            &ToPtr, ToPtr + NumBytes,
2187                            strictConversion);
2188 
2189   // ConvertUTF8toUTF16 returns the length in ToPtr.
2190   StringLength = ToPtr - &ToBuf[0];
2191 
2192   // Add an explicit null.
2193   *ToPtr = 0;
2194   return Map.
2195     GetOrCreateValue(StringRef(reinterpret_cast<const char *>(ToBuf.data()),
2196                                (StringLength + 1) * 2));
2197 }
2198 
2199 static llvm::StringMapEntry<llvm::Constant*> &
2200 GetConstantStringEntry(llvm::StringMap<llvm::Constant*> &Map,
2201                        const StringLiteral *Literal,
2202                        unsigned &StringLength) {
2203   StringRef String = Literal->getString();
2204   StringLength = String.size();
2205   return Map.GetOrCreateValue(String);
2206 }
2207 
2208 llvm::Constant *
2209 CodeGenModule::GetAddrOfConstantCFString(const StringLiteral *Literal) {
2210   unsigned StringLength = 0;
2211   bool isUTF16 = false;
2212   llvm::StringMapEntry<llvm::Constant*> &Entry =
2213     GetConstantCFStringEntry(CFConstantStringMap, Literal,
2214                              getDataLayout().isLittleEndian(),
2215                              isUTF16, StringLength);
2216 
2217   if (llvm::Constant *C = Entry.getValue())
2218     return C;
2219 
2220   llvm::Constant *Zero = llvm::Constant::getNullValue(Int32Ty);
2221   llvm::Constant *Zeros[] = { Zero, Zero };
2222   llvm::Value *V;
2223 
2224   // If we don't already have it, get __CFConstantStringClassReference.
2225   if (!CFConstantStringClassRef) {
2226     llvm::Type *Ty = getTypes().ConvertType(getContext().IntTy);
2227     Ty = llvm::ArrayType::get(Ty, 0);
2228     llvm::Constant *GV = CreateRuntimeVariable(Ty,
2229                                            "__CFConstantStringClassReference");
2230     // Decay array -> ptr
2231     V = llvm::ConstantExpr::getGetElementPtr(GV, Zeros);
2232     CFConstantStringClassRef = V;
2233   }
2234   else
2235     V = CFConstantStringClassRef;
2236 
2237   QualType CFTy = getContext().getCFConstantStringType();
2238 
2239   llvm::StructType *STy =
2240     cast<llvm::StructType>(getTypes().ConvertType(CFTy));
2241 
2242   llvm::Constant *Fields[4];
2243 
2244   // Class pointer.
2245   Fields[0] = cast<llvm::ConstantExpr>(V);
2246 
2247   // Flags.
2248   llvm::Type *Ty = getTypes().ConvertType(getContext().UnsignedIntTy);
2249   Fields[1] = isUTF16 ? llvm::ConstantInt::get(Ty, 0x07d0) :
2250     llvm::ConstantInt::get(Ty, 0x07C8);
2251 
2252   // String pointer.
2253   llvm::Constant *C = 0;
2254   if (isUTF16) {
2255     ArrayRef<uint16_t> Arr =
2256       llvm::makeArrayRef<uint16_t>(reinterpret_cast<uint16_t*>(
2257                                      const_cast<char *>(Entry.getKey().data())),
2258                                    Entry.getKey().size() / 2);
2259     C = llvm::ConstantDataArray::get(VMContext, Arr);
2260   } else {
2261     C = llvm::ConstantDataArray::getString(VMContext, Entry.getKey());
2262   }
2263 
2264   llvm::GlobalValue::LinkageTypes Linkage;
2265   if (isUTF16)
2266     // FIXME: why do utf strings get "_" labels instead of "L" labels?
2267     Linkage = llvm::GlobalValue::InternalLinkage;
2268   else
2269     // FIXME: With OS X ld 123.2 (xcode 4) and LTO we would get a linker error
2270     // when using private linkage. It is not clear if this is a bug in ld
2271     // or a reasonable new restriction.
2272     Linkage = llvm::GlobalValue::LinkerPrivateLinkage;
2273 
2274   // Note: -fwritable-strings doesn't make the backing store strings of
2275   // CFStrings writable. (See <rdar://problem/10657500>)
2276   llvm::GlobalVariable *GV =
2277     new llvm::GlobalVariable(getModule(), C->getType(), /*isConstant=*/true,
2278                              Linkage, C, ".str");
2279   GV->setUnnamedAddr(true);
2280   // Don't enforce the target's minimum global alignment, since the only use
2281   // of the string is via this class initializer.
2282   if (isUTF16) {
2283     CharUnits Align = getContext().getTypeAlignInChars(getContext().ShortTy);
2284     GV->setAlignment(Align.getQuantity());
2285   } else {
2286     CharUnits Align = getContext().getTypeAlignInChars(getContext().CharTy);
2287     GV->setAlignment(Align.getQuantity());
2288   }
2289 
2290   // String.
2291   Fields[2] = llvm::ConstantExpr::getGetElementPtr(GV, Zeros);
2292 
2293   if (isUTF16)
2294     // Cast the UTF16 string to the correct type.
2295     Fields[2] = llvm::ConstantExpr::getBitCast(Fields[2], Int8PtrTy);
2296 
2297   // String length.
2298   Ty = getTypes().ConvertType(getContext().LongTy);
2299   Fields[3] = llvm::ConstantInt::get(Ty, StringLength);
2300 
2301   // The struct.
2302   C = llvm::ConstantStruct::get(STy, Fields);
2303   GV = new llvm::GlobalVariable(getModule(), C->getType(), true,
2304                                 llvm::GlobalVariable::PrivateLinkage, C,
2305                                 "_unnamed_cfstring_");
2306   if (const char *Sect = getTarget().getCFStringSection())
2307     GV->setSection(Sect);
2308   Entry.setValue(GV);
2309 
2310   return GV;
2311 }
2312 
2313 static RecordDecl *
2314 CreateRecordDecl(const ASTContext &Ctx, RecordDecl::TagKind TK,
2315                  DeclContext *DC, IdentifierInfo *Id) {
2316   SourceLocation Loc;
2317   if (Ctx.getLangOpts().CPlusPlus)
2318     return CXXRecordDecl::Create(Ctx, TK, DC, Loc, Loc, Id);
2319   else
2320     return RecordDecl::Create(Ctx, TK, DC, Loc, Loc, Id);
2321 }
2322 
2323 llvm::Constant *
2324 CodeGenModule::GetAddrOfConstantString(const StringLiteral *Literal) {
2325   unsigned StringLength = 0;
2326   llvm::StringMapEntry<llvm::Constant*> &Entry =
2327     GetConstantStringEntry(CFConstantStringMap, Literal, StringLength);
2328 
2329   if (llvm::Constant *C = Entry.getValue())
2330     return C;
2331 
2332   llvm::Constant *Zero = llvm::Constant::getNullValue(Int32Ty);
2333   llvm::Constant *Zeros[] = { Zero, Zero };
2334   llvm::Value *V;
2335   // If we don't already have it, get _NSConstantStringClassReference.
2336   if (!ConstantStringClassRef) {
2337     std::string StringClass(getLangOpts().ObjCConstantStringClass);
2338     llvm::Type *Ty = getTypes().ConvertType(getContext().IntTy);
2339     llvm::Constant *GV;
2340     if (LangOpts.ObjCRuntime.isNonFragile()) {
2341       std::string str =
2342         StringClass.empty() ? "OBJC_CLASS_$_NSConstantString"
2343                             : "OBJC_CLASS_$_" + StringClass;
2344       GV = getObjCRuntime().GetClassGlobal(str);
2345       // Make sure the result is of the correct type.
2346       llvm::Type *PTy = llvm::PointerType::getUnqual(Ty);
2347       V = llvm::ConstantExpr::getBitCast(GV, PTy);
2348       ConstantStringClassRef = V;
2349     } else {
2350       std::string str =
2351         StringClass.empty() ? "_NSConstantStringClassReference"
2352                             : "_" + StringClass + "ClassReference";
2353       llvm::Type *PTy = llvm::ArrayType::get(Ty, 0);
2354       GV = CreateRuntimeVariable(PTy, str);
2355       // Decay array -> ptr
2356       V = llvm::ConstantExpr::getGetElementPtr(GV, Zeros);
2357       ConstantStringClassRef = V;
2358     }
2359   }
2360   else
2361     V = ConstantStringClassRef;
2362 
2363   if (!NSConstantStringType) {
2364     // Construct the type for a constant NSString.
2365     RecordDecl *D = CreateRecordDecl(Context, TTK_Struct,
2366                                      Context.getTranslationUnitDecl(),
2367                                    &Context.Idents.get("__builtin_NSString"));
2368     D->startDefinition();
2369 
2370     QualType FieldTypes[3];
2371 
2372     // const int *isa;
2373     FieldTypes[0] = Context.getPointerType(Context.IntTy.withConst());
2374     // const char *str;
2375     FieldTypes[1] = Context.getPointerType(Context.CharTy.withConst());
2376     // unsigned int length;
2377     FieldTypes[2] = Context.UnsignedIntTy;
2378 
2379     // Create fields
2380     for (unsigned i = 0; i < 3; ++i) {
2381       FieldDecl *Field = FieldDecl::Create(Context, D,
2382                                            SourceLocation(),
2383                                            SourceLocation(), 0,
2384                                            FieldTypes[i], /*TInfo=*/0,
2385                                            /*BitWidth=*/0,
2386                                            /*Mutable=*/false,
2387                                            ICIS_NoInit);
2388       Field->setAccess(AS_public);
2389       D->addDecl(Field);
2390     }
2391 
2392     D->completeDefinition();
2393     QualType NSTy = Context.getTagDeclType(D);
2394     NSConstantStringType = cast<llvm::StructType>(getTypes().ConvertType(NSTy));
2395   }
2396 
2397   llvm::Constant *Fields[3];
2398 
2399   // Class pointer.
2400   Fields[0] = cast<llvm::ConstantExpr>(V);
2401 
2402   // String pointer.
2403   llvm::Constant *C =
2404     llvm::ConstantDataArray::getString(VMContext, Entry.getKey());
2405 
2406   llvm::GlobalValue::LinkageTypes Linkage;
2407   bool isConstant;
2408   Linkage = llvm::GlobalValue::PrivateLinkage;
2409   isConstant = !LangOpts.WritableStrings;
2410 
2411   llvm::GlobalVariable *GV =
2412   new llvm::GlobalVariable(getModule(), C->getType(), isConstant, Linkage, C,
2413                            ".str");
2414   GV->setUnnamedAddr(true);
2415   // Don't enforce the target's minimum global alignment, since the only use
2416   // of the string is via this class initializer.
2417   CharUnits Align = getContext().getTypeAlignInChars(getContext().CharTy);
2418   GV->setAlignment(Align.getQuantity());
2419   Fields[1] = llvm::ConstantExpr::getGetElementPtr(GV, Zeros);
2420 
2421   // String length.
2422   llvm::Type *Ty = getTypes().ConvertType(getContext().UnsignedIntTy);
2423   Fields[2] = llvm::ConstantInt::get(Ty, StringLength);
2424 
2425   // The struct.
2426   C = llvm::ConstantStruct::get(NSConstantStringType, Fields);
2427   GV = new llvm::GlobalVariable(getModule(), C->getType(), true,
2428                                 llvm::GlobalVariable::PrivateLinkage, C,
2429                                 "_unnamed_nsstring_");
2430   // FIXME. Fix section.
2431   if (const char *Sect =
2432         LangOpts.ObjCRuntime.isNonFragile()
2433           ? getTarget().getNSStringNonFragileABISection()
2434           : getTarget().getNSStringSection())
2435     GV->setSection(Sect);
2436   Entry.setValue(GV);
2437 
2438   return GV;
2439 }
2440 
2441 QualType CodeGenModule::getObjCFastEnumerationStateType() {
2442   if (ObjCFastEnumerationStateType.isNull()) {
2443     RecordDecl *D = CreateRecordDecl(Context, TTK_Struct,
2444                                      Context.getTranslationUnitDecl(),
2445                       &Context.Idents.get("__objcFastEnumerationState"));
2446     D->startDefinition();
2447 
2448     QualType FieldTypes[] = {
2449       Context.UnsignedLongTy,
2450       Context.getPointerType(Context.getObjCIdType()),
2451       Context.getPointerType(Context.UnsignedLongTy),
2452       Context.getConstantArrayType(Context.UnsignedLongTy,
2453                            llvm::APInt(32, 5), ArrayType::Normal, 0)
2454     };
2455 
2456     for (size_t i = 0; i < 4; ++i) {
2457       FieldDecl *Field = FieldDecl::Create(Context,
2458                                            D,
2459                                            SourceLocation(),
2460                                            SourceLocation(), 0,
2461                                            FieldTypes[i], /*TInfo=*/0,
2462                                            /*BitWidth=*/0,
2463                                            /*Mutable=*/false,
2464                                            ICIS_NoInit);
2465       Field->setAccess(AS_public);
2466       D->addDecl(Field);
2467     }
2468 
2469     D->completeDefinition();
2470     ObjCFastEnumerationStateType = Context.getTagDeclType(D);
2471   }
2472 
2473   return ObjCFastEnumerationStateType;
2474 }
2475 
2476 llvm::Constant *
2477 CodeGenModule::GetConstantArrayFromStringLiteral(const StringLiteral *E) {
2478   assert(!E->getType()->isPointerType() && "Strings are always arrays");
2479 
2480   // Don't emit it as the address of the string, emit the string data itself
2481   // as an inline array.
2482   if (E->getCharByteWidth() == 1) {
2483     SmallString<64> Str(E->getString());
2484 
2485     // Resize the string to the right size, which is indicated by its type.
2486     const ConstantArrayType *CAT = Context.getAsConstantArrayType(E->getType());
2487     Str.resize(CAT->getSize().getZExtValue());
2488     return llvm::ConstantDataArray::getString(VMContext, Str, false);
2489   }
2490 
2491   llvm::ArrayType *AType =
2492     cast<llvm::ArrayType>(getTypes().ConvertType(E->getType()));
2493   llvm::Type *ElemTy = AType->getElementType();
2494   unsigned NumElements = AType->getNumElements();
2495 
2496   // Wide strings have either 2-byte or 4-byte elements.
2497   if (ElemTy->getPrimitiveSizeInBits() == 16) {
2498     SmallVector<uint16_t, 32> Elements;
2499     Elements.reserve(NumElements);
2500 
2501     for(unsigned i = 0, e = E->getLength(); i != e; ++i)
2502       Elements.push_back(E->getCodeUnit(i));
2503     Elements.resize(NumElements);
2504     return llvm::ConstantDataArray::get(VMContext, Elements);
2505   }
2506 
2507   assert(ElemTy->getPrimitiveSizeInBits() == 32);
2508   SmallVector<uint32_t, 32> Elements;
2509   Elements.reserve(NumElements);
2510 
2511   for(unsigned i = 0, e = E->getLength(); i != e; ++i)
2512     Elements.push_back(E->getCodeUnit(i));
2513   Elements.resize(NumElements);
2514   return llvm::ConstantDataArray::get(VMContext, Elements);
2515 }
2516 
2517 /// GetAddrOfConstantStringFromLiteral - Return a pointer to a
2518 /// constant array for the given string literal.
2519 llvm::Constant *
2520 CodeGenModule::GetAddrOfConstantStringFromLiteral(const StringLiteral *S) {
2521   CharUnits Align = getContext().getAlignOfGlobalVarInChars(S->getType());
2522   if (S->isAscii() || S->isUTF8()) {
2523     SmallString<64> Str(S->getString());
2524 
2525     // Resize the string to the right size, which is indicated by its type.
2526     const ConstantArrayType *CAT = Context.getAsConstantArrayType(S->getType());
2527     Str.resize(CAT->getSize().getZExtValue());
2528     return GetAddrOfConstantString(Str, /*GlobalName*/ 0, Align.getQuantity());
2529   }
2530 
2531   // FIXME: the following does not memoize wide strings.
2532   llvm::Constant *C = GetConstantArrayFromStringLiteral(S);
2533   llvm::GlobalVariable *GV =
2534     new llvm::GlobalVariable(getModule(),C->getType(),
2535                              !LangOpts.WritableStrings,
2536                              llvm::GlobalValue::PrivateLinkage,
2537                              C,".str");
2538 
2539   GV->setAlignment(Align.getQuantity());
2540   GV->setUnnamedAddr(true);
2541   return GV;
2542 }
2543 
2544 /// GetAddrOfConstantStringFromObjCEncode - Return a pointer to a constant
2545 /// array for the given ObjCEncodeExpr node.
2546 llvm::Constant *
2547 CodeGenModule::GetAddrOfConstantStringFromObjCEncode(const ObjCEncodeExpr *E) {
2548   std::string Str;
2549   getContext().getObjCEncodingForType(E->getEncodedType(), Str);
2550 
2551   return GetAddrOfConstantCString(Str);
2552 }
2553 
2554 
2555 /// GenerateWritableString -- Creates storage for a string literal.
2556 static llvm::GlobalVariable *GenerateStringLiteral(StringRef str,
2557                                              bool constant,
2558                                              CodeGenModule &CGM,
2559                                              const char *GlobalName,
2560                                              unsigned Alignment) {
2561   // Create Constant for this string literal. Don't add a '\0'.
2562   llvm::Constant *C =
2563       llvm::ConstantDataArray::getString(CGM.getLLVMContext(), str, false);
2564 
2565   // Create a global variable for this string
2566   llvm::GlobalVariable *GV =
2567     new llvm::GlobalVariable(CGM.getModule(), C->getType(), constant,
2568                              llvm::GlobalValue::PrivateLinkage,
2569                              C, GlobalName);
2570   GV->setAlignment(Alignment);
2571   GV->setUnnamedAddr(true);
2572   return GV;
2573 }
2574 
2575 /// GetAddrOfConstantString - Returns a pointer to a character array
2576 /// containing the literal. This contents are exactly that of the
2577 /// given string, i.e. it will not be null terminated automatically;
2578 /// see GetAddrOfConstantCString. Note that whether the result is
2579 /// actually a pointer to an LLVM constant depends on
2580 /// Feature.WriteableStrings.
2581 ///
2582 /// The result has pointer to array type.
2583 llvm::Constant *CodeGenModule::GetAddrOfConstantString(StringRef Str,
2584                                                        const char *GlobalName,
2585                                                        unsigned Alignment) {
2586   // Get the default prefix if a name wasn't specified.
2587   if (!GlobalName)
2588     GlobalName = ".str";
2589 
2590   if (Alignment == 0)
2591     Alignment = getContext().getAlignOfGlobalVarInChars(getContext().CharTy)
2592       .getQuantity();
2593 
2594   // Don't share any string literals if strings aren't constant.
2595   if (LangOpts.WritableStrings)
2596     return GenerateStringLiteral(Str, false, *this, GlobalName, Alignment);
2597 
2598   llvm::StringMapEntry<llvm::GlobalVariable *> &Entry =
2599     ConstantStringMap.GetOrCreateValue(Str);
2600 
2601   if (llvm::GlobalVariable *GV = Entry.getValue()) {
2602     if (Alignment > GV->getAlignment()) {
2603       GV->setAlignment(Alignment);
2604     }
2605     return GV;
2606   }
2607 
2608   // Create a global variable for this.
2609   llvm::GlobalVariable *GV = GenerateStringLiteral(Str, true, *this, GlobalName,
2610                                                    Alignment);
2611   Entry.setValue(GV);
2612   return GV;
2613 }
2614 
2615 /// GetAddrOfConstantCString - Returns a pointer to a character
2616 /// array containing the literal and a terminating '\0'
2617 /// character. The result has pointer to array type.
2618 llvm::Constant *CodeGenModule::GetAddrOfConstantCString(const std::string &Str,
2619                                                         const char *GlobalName,
2620                                                         unsigned Alignment) {
2621   StringRef StrWithNull(Str.c_str(), Str.size() + 1);
2622   return GetAddrOfConstantString(StrWithNull, GlobalName, Alignment);
2623 }
2624 
2625 llvm::Constant *CodeGenModule::GetAddrOfGlobalTemporary(
2626     const MaterializeTemporaryExpr *E, const Expr *Init) {
2627   assert((E->getStorageDuration() == SD_Static ||
2628           E->getStorageDuration() == SD_Thread) && "not a global temporary");
2629   const VarDecl *VD = cast<VarDecl>(E->getExtendingDecl());
2630 
2631   // If we're not materializing a subobject of the temporary, keep the
2632   // cv-qualifiers from the type of the MaterializeTemporaryExpr.
2633   QualType MaterializedType = Init->getType();
2634   if (Init == E->GetTemporaryExpr())
2635     MaterializedType = E->getType();
2636 
2637   llvm::Constant *&Slot = MaterializedGlobalTemporaryMap[E];
2638   if (Slot)
2639     return Slot;
2640 
2641   // FIXME: If an externally-visible declaration extends multiple temporaries,
2642   // we need to give each temporary the same name in every translation unit (and
2643   // we also need to make the temporaries externally-visible).
2644   SmallString<256> Name;
2645   llvm::raw_svector_ostream Out(Name);
2646   getCXXABI().getMangleContext().mangleReferenceTemporary(VD, Out);
2647   Out.flush();
2648 
2649   APValue *Value = 0;
2650   if (E->getStorageDuration() == SD_Static) {
2651     // We might have a cached constant initializer for this temporary. Note
2652     // that this might have a different value from the value computed by
2653     // evaluating the initializer if the surrounding constant expression
2654     // modifies the temporary.
2655     Value = getContext().getMaterializedTemporaryValue(E, false);
2656     if (Value && Value->isUninit())
2657       Value = 0;
2658   }
2659 
2660   // Try evaluating it now, it might have a constant initializer.
2661   Expr::EvalResult EvalResult;
2662   if (!Value && Init->EvaluateAsRValue(EvalResult, getContext()) &&
2663       !EvalResult.hasSideEffects())
2664     Value = &EvalResult.Val;
2665 
2666   llvm::Constant *InitialValue = 0;
2667   bool Constant = false;
2668   llvm::Type *Type;
2669   if (Value) {
2670     // The temporary has a constant initializer, use it.
2671     InitialValue = EmitConstantValue(*Value, MaterializedType, 0);
2672     Constant = isTypeConstant(MaterializedType, /*ExcludeCtor*/Value);
2673     Type = InitialValue->getType();
2674   } else {
2675     // No initializer, the initialization will be provided when we
2676     // initialize the declaration which performed lifetime extension.
2677     Type = getTypes().ConvertTypeForMem(MaterializedType);
2678   }
2679 
2680   // Create a global variable for this lifetime-extended temporary.
2681   llvm::GlobalVariable *GV =
2682     new llvm::GlobalVariable(getModule(), Type, Constant,
2683                              llvm::GlobalValue::PrivateLinkage,
2684                              InitialValue, Name.c_str());
2685   GV->setAlignment(
2686       getContext().getTypeAlignInChars(MaterializedType).getQuantity());
2687   if (VD->getTLSKind())
2688     setTLSMode(GV, *VD);
2689   Slot = GV;
2690   return GV;
2691 }
2692 
2693 /// EmitObjCPropertyImplementations - Emit information for synthesized
2694 /// properties for an implementation.
2695 void CodeGenModule::EmitObjCPropertyImplementations(const
2696                                                     ObjCImplementationDecl *D) {
2697   for (ObjCImplementationDecl::propimpl_iterator
2698          i = D->propimpl_begin(), e = D->propimpl_end(); i != e; ++i) {
2699     ObjCPropertyImplDecl *PID = *i;
2700 
2701     // Dynamic is just for type-checking.
2702     if (PID->getPropertyImplementation() == ObjCPropertyImplDecl::Synthesize) {
2703       ObjCPropertyDecl *PD = PID->getPropertyDecl();
2704 
2705       // Determine which methods need to be implemented, some may have
2706       // been overridden. Note that ::isPropertyAccessor is not the method
2707       // we want, that just indicates if the decl came from a
2708       // property. What we want to know is if the method is defined in
2709       // this implementation.
2710       if (!D->getInstanceMethod(PD->getGetterName()))
2711         CodeGenFunction(*this).GenerateObjCGetter(
2712                                  const_cast<ObjCImplementationDecl *>(D), PID);
2713       if (!PD->isReadOnly() &&
2714           !D->getInstanceMethod(PD->getSetterName()))
2715         CodeGenFunction(*this).GenerateObjCSetter(
2716                                  const_cast<ObjCImplementationDecl *>(D), PID);
2717     }
2718   }
2719 }
2720 
2721 static bool needsDestructMethod(ObjCImplementationDecl *impl) {
2722   const ObjCInterfaceDecl *iface = impl->getClassInterface();
2723   for (const ObjCIvarDecl *ivar = iface->all_declared_ivar_begin();
2724        ivar; ivar = ivar->getNextIvar())
2725     if (ivar->getType().isDestructedType())
2726       return true;
2727 
2728   return false;
2729 }
2730 
2731 /// EmitObjCIvarInitializations - Emit information for ivar initialization
2732 /// for an implementation.
2733 void CodeGenModule::EmitObjCIvarInitializations(ObjCImplementationDecl *D) {
2734   // We might need a .cxx_destruct even if we don't have any ivar initializers.
2735   if (needsDestructMethod(D)) {
2736     IdentifierInfo *II = &getContext().Idents.get(".cxx_destruct");
2737     Selector cxxSelector = getContext().Selectors.getSelector(0, &II);
2738     ObjCMethodDecl *DTORMethod =
2739       ObjCMethodDecl::Create(getContext(), D->getLocation(), D->getLocation(),
2740                              cxxSelector, getContext().VoidTy, 0, D,
2741                              /*isInstance=*/true, /*isVariadic=*/false,
2742                           /*isPropertyAccessor=*/true, /*isImplicitlyDeclared=*/true,
2743                              /*isDefined=*/false, ObjCMethodDecl::Required);
2744     D->addInstanceMethod(DTORMethod);
2745     CodeGenFunction(*this).GenerateObjCCtorDtorMethod(D, DTORMethod, false);
2746     D->setHasDestructors(true);
2747   }
2748 
2749   // If the implementation doesn't have any ivar initializers, we don't need
2750   // a .cxx_construct.
2751   if (D->getNumIvarInitializers() == 0)
2752     return;
2753 
2754   IdentifierInfo *II = &getContext().Idents.get(".cxx_construct");
2755   Selector cxxSelector = getContext().Selectors.getSelector(0, &II);
2756   // The constructor returns 'self'.
2757   ObjCMethodDecl *CTORMethod = ObjCMethodDecl::Create(getContext(),
2758                                                 D->getLocation(),
2759                                                 D->getLocation(),
2760                                                 cxxSelector,
2761                                                 getContext().getObjCIdType(), 0,
2762                                                 D, /*isInstance=*/true,
2763                                                 /*isVariadic=*/false,
2764                                                 /*isPropertyAccessor=*/true,
2765                                                 /*isImplicitlyDeclared=*/true,
2766                                                 /*isDefined=*/false,
2767                                                 ObjCMethodDecl::Required);
2768   D->addInstanceMethod(CTORMethod);
2769   CodeGenFunction(*this).GenerateObjCCtorDtorMethod(D, CTORMethod, true);
2770   D->setHasNonZeroConstructors(true);
2771 }
2772 
2773 /// EmitNamespace - Emit all declarations in a namespace.
2774 void CodeGenModule::EmitNamespace(const NamespaceDecl *ND) {
2775   for (RecordDecl::decl_iterator I = ND->decls_begin(), E = ND->decls_end();
2776        I != E; ++I)
2777     EmitTopLevelDecl(*I);
2778 }
2779 
2780 // EmitLinkageSpec - Emit all declarations in a linkage spec.
2781 void CodeGenModule::EmitLinkageSpec(const LinkageSpecDecl *LSD) {
2782   if (LSD->getLanguage() != LinkageSpecDecl::lang_c &&
2783       LSD->getLanguage() != LinkageSpecDecl::lang_cxx) {
2784     ErrorUnsupported(LSD, "linkage spec");
2785     return;
2786   }
2787 
2788   for (RecordDecl::decl_iterator I = LSD->decls_begin(), E = LSD->decls_end();
2789        I != E; ++I) {
2790     // Meta-data for ObjC class includes references to implemented methods.
2791     // Generate class's method definitions first.
2792     if (ObjCImplDecl *OID = dyn_cast<ObjCImplDecl>(*I)) {
2793       for (ObjCContainerDecl::method_iterator M = OID->meth_begin(),
2794            MEnd = OID->meth_end();
2795            M != MEnd; ++M)
2796         EmitTopLevelDecl(*M);
2797     }
2798     EmitTopLevelDecl(*I);
2799   }
2800 }
2801 
2802 /// EmitTopLevelDecl - Emit code for a single top level declaration.
2803 void CodeGenModule::EmitTopLevelDecl(Decl *D) {
2804   // If an error has occurred, stop code generation, but continue
2805   // parsing and semantic analysis (to ensure all warnings and errors
2806   // are emitted).
2807   if (Diags.hasErrorOccurred())
2808     return;
2809 
2810   // Ignore dependent declarations.
2811   if (D->getDeclContext() && D->getDeclContext()->isDependentContext())
2812     return;
2813 
2814   switch (D->getKind()) {
2815   case Decl::CXXConversion:
2816   case Decl::CXXMethod:
2817   case Decl::Function:
2818     // Skip function templates
2819     if (cast<FunctionDecl>(D)->getDescribedFunctionTemplate() ||
2820         cast<FunctionDecl>(D)->isLateTemplateParsed())
2821       return;
2822 
2823     EmitGlobal(cast<FunctionDecl>(D));
2824     break;
2825 
2826   case Decl::Var:
2827     EmitGlobal(cast<VarDecl>(D));
2828     break;
2829 
2830   // Indirect fields from global anonymous structs and unions can be
2831   // ignored; only the actual variable requires IR gen support.
2832   case Decl::IndirectField:
2833     break;
2834 
2835   // C++ Decls
2836   case Decl::Namespace:
2837     EmitNamespace(cast<NamespaceDecl>(D));
2838     break;
2839     // No code generation needed.
2840   case Decl::UsingShadow:
2841   case Decl::Using:
2842   case Decl::ClassTemplate:
2843   case Decl::FunctionTemplate:
2844   case Decl::TypeAliasTemplate:
2845   case Decl::Block:
2846   case Decl::Empty:
2847     break;
2848   case Decl::NamespaceAlias:
2849     if (CGDebugInfo *DI = getModuleDebugInfo())
2850         DI->EmitNamespaceAlias(cast<NamespaceAliasDecl>(*D));
2851     return;
2852   case Decl::UsingDirective: // using namespace X; [C++]
2853     if (CGDebugInfo *DI = getModuleDebugInfo())
2854       DI->EmitUsingDirective(cast<UsingDirectiveDecl>(*D));
2855     return;
2856   case Decl::CXXConstructor:
2857     // Skip function templates
2858     if (cast<FunctionDecl>(D)->getDescribedFunctionTemplate() ||
2859         cast<FunctionDecl>(D)->isLateTemplateParsed())
2860       return;
2861 
2862     EmitCXXConstructors(cast<CXXConstructorDecl>(D));
2863     break;
2864   case Decl::CXXDestructor:
2865     if (cast<FunctionDecl>(D)->isLateTemplateParsed())
2866       return;
2867     EmitCXXDestructors(cast<CXXDestructorDecl>(D));
2868     break;
2869 
2870   case Decl::StaticAssert:
2871     // Nothing to do.
2872     break;
2873 
2874   // Objective-C Decls
2875 
2876   // Forward declarations, no (immediate) code generation.
2877   case Decl::ObjCInterface:
2878   case Decl::ObjCCategory:
2879     break;
2880 
2881   case Decl::ObjCProtocol: {
2882     ObjCProtocolDecl *Proto = cast<ObjCProtocolDecl>(D);
2883     if (Proto->isThisDeclarationADefinition())
2884       ObjCRuntime->GenerateProtocol(Proto);
2885     break;
2886   }
2887 
2888   case Decl::ObjCCategoryImpl:
2889     // Categories have properties but don't support synthesize so we
2890     // can ignore them here.
2891     ObjCRuntime->GenerateCategory(cast<ObjCCategoryImplDecl>(D));
2892     break;
2893 
2894   case Decl::ObjCImplementation: {
2895     ObjCImplementationDecl *OMD = cast<ObjCImplementationDecl>(D);
2896     EmitObjCPropertyImplementations(OMD);
2897     EmitObjCIvarInitializations(OMD);
2898     ObjCRuntime->GenerateClass(OMD);
2899     // Emit global variable debug information.
2900     if (CGDebugInfo *DI = getModuleDebugInfo())
2901       if (getCodeGenOpts().getDebugInfo() >= CodeGenOptions::LimitedDebugInfo)
2902         DI->getOrCreateInterfaceType(getContext().getObjCInterfaceType(
2903             OMD->getClassInterface()), OMD->getLocation());
2904     break;
2905   }
2906   case Decl::ObjCMethod: {
2907     ObjCMethodDecl *OMD = cast<ObjCMethodDecl>(D);
2908     // If this is not a prototype, emit the body.
2909     if (OMD->getBody())
2910       CodeGenFunction(*this).GenerateObjCMethod(OMD);
2911     break;
2912   }
2913   case Decl::ObjCCompatibleAlias:
2914     ObjCRuntime->RegisterAlias(cast<ObjCCompatibleAliasDecl>(D));
2915     break;
2916 
2917   case Decl::LinkageSpec:
2918     EmitLinkageSpec(cast<LinkageSpecDecl>(D));
2919     break;
2920 
2921   case Decl::FileScopeAsm: {
2922     FileScopeAsmDecl *AD = cast<FileScopeAsmDecl>(D);
2923     StringRef AsmString = AD->getAsmString()->getString();
2924 
2925     const std::string &S = getModule().getModuleInlineAsm();
2926     if (S.empty())
2927       getModule().setModuleInlineAsm(AsmString);
2928     else if (S.end()[-1] == '\n')
2929       getModule().setModuleInlineAsm(S + AsmString.str());
2930     else
2931       getModule().setModuleInlineAsm(S + '\n' + AsmString.str());
2932     break;
2933   }
2934 
2935   case Decl::Import: {
2936     ImportDecl *Import = cast<ImportDecl>(D);
2937 
2938     // Ignore import declarations that come from imported modules.
2939     if (clang::Module *Owner = Import->getOwningModule()) {
2940       if (getLangOpts().CurrentModule.empty() ||
2941           Owner->getTopLevelModule()->Name == getLangOpts().CurrentModule)
2942         break;
2943     }
2944 
2945     ImportedModules.insert(Import->getImportedModule());
2946     break;
2947  }
2948 
2949   default:
2950     // Make sure we handled everything we should, every other kind is a
2951     // non-top-level decl.  FIXME: Would be nice to have an isTopLevelDeclKind
2952     // function. Need to recode Decl::Kind to do that easily.
2953     assert(isa<TypeDecl>(D) && "Unsupported decl kind");
2954   }
2955 }
2956 
2957 /// Turns the given pointer into a constant.
2958 static llvm::Constant *GetPointerConstant(llvm::LLVMContext &Context,
2959                                           const void *Ptr) {
2960   uintptr_t PtrInt = reinterpret_cast<uintptr_t>(Ptr);
2961   llvm::Type *i64 = llvm::Type::getInt64Ty(Context);
2962   return llvm::ConstantInt::get(i64, PtrInt);
2963 }
2964 
2965 static void EmitGlobalDeclMetadata(CodeGenModule &CGM,
2966                                    llvm::NamedMDNode *&GlobalMetadata,
2967                                    GlobalDecl D,
2968                                    llvm::GlobalValue *Addr) {
2969   if (!GlobalMetadata)
2970     GlobalMetadata =
2971       CGM.getModule().getOrInsertNamedMetadata("clang.global.decl.ptrs");
2972 
2973   // TODO: should we report variant information for ctors/dtors?
2974   llvm::Value *Ops[] = {
2975     Addr,
2976     GetPointerConstant(CGM.getLLVMContext(), D.getDecl())
2977   };
2978   GlobalMetadata->addOperand(llvm::MDNode::get(CGM.getLLVMContext(), Ops));
2979 }
2980 
2981 /// For each function which is declared within an extern "C" region and marked
2982 /// as 'used', but has internal linkage, create an alias from the unmangled
2983 /// name to the mangled name if possible. People expect to be able to refer
2984 /// to such functions with an unmangled name from inline assembly within the
2985 /// same translation unit.
2986 void CodeGenModule::EmitStaticExternCAliases() {
2987   for (StaticExternCMap::iterator I = StaticExternCValues.begin(),
2988                                   E = StaticExternCValues.end();
2989        I != E; ++I) {
2990     IdentifierInfo *Name = I->first;
2991     llvm::GlobalValue *Val = I->second;
2992     if (Val && !getModule().getNamedValue(Name->getName()))
2993       AddUsedGlobal(new llvm::GlobalAlias(Val->getType(), Val->getLinkage(),
2994                                           Name->getName(), Val, &getModule()));
2995   }
2996 }
2997 
2998 /// Emits metadata nodes associating all the global values in the
2999 /// current module with the Decls they came from.  This is useful for
3000 /// projects using IR gen as a subroutine.
3001 ///
3002 /// Since there's currently no way to associate an MDNode directly
3003 /// with an llvm::GlobalValue, we create a global named metadata
3004 /// with the name 'clang.global.decl.ptrs'.
3005 void CodeGenModule::EmitDeclMetadata() {
3006   llvm::NamedMDNode *GlobalMetadata = 0;
3007 
3008   // StaticLocalDeclMap
3009   for (llvm::DenseMap<GlobalDecl,StringRef>::iterator
3010          I = MangledDeclNames.begin(), E = MangledDeclNames.end();
3011        I != E; ++I) {
3012     llvm::GlobalValue *Addr = getModule().getNamedValue(I->second);
3013     EmitGlobalDeclMetadata(*this, GlobalMetadata, I->first, Addr);
3014   }
3015 }
3016 
3017 /// Emits metadata nodes for all the local variables in the current
3018 /// function.
3019 void CodeGenFunction::EmitDeclMetadata() {
3020   if (LocalDeclMap.empty()) return;
3021 
3022   llvm::LLVMContext &Context = getLLVMContext();
3023 
3024   // Find the unique metadata ID for this name.
3025   unsigned DeclPtrKind = Context.getMDKindID("clang.decl.ptr");
3026 
3027   llvm::NamedMDNode *GlobalMetadata = 0;
3028 
3029   for (llvm::DenseMap<const Decl*, llvm::Value*>::iterator
3030          I = LocalDeclMap.begin(), E = LocalDeclMap.end(); I != E; ++I) {
3031     const Decl *D = I->first;
3032     llvm::Value *Addr = I->second;
3033 
3034     if (llvm::AllocaInst *Alloca = dyn_cast<llvm::AllocaInst>(Addr)) {
3035       llvm::Value *DAddr = GetPointerConstant(getLLVMContext(), D);
3036       Alloca->setMetadata(DeclPtrKind, llvm::MDNode::get(Context, DAddr));
3037     } else if (llvm::GlobalValue *GV = dyn_cast<llvm::GlobalValue>(Addr)) {
3038       GlobalDecl GD = GlobalDecl(cast<VarDecl>(D));
3039       EmitGlobalDeclMetadata(CGM, GlobalMetadata, GD, GV);
3040     }
3041   }
3042 }
3043 
3044 void CodeGenModule::EmitCoverageFile() {
3045   if (!getCodeGenOpts().CoverageFile.empty()) {
3046     if (llvm::NamedMDNode *CUNode = TheModule.getNamedMetadata("llvm.dbg.cu")) {
3047       llvm::NamedMDNode *GCov = TheModule.getOrInsertNamedMetadata("llvm.gcov");
3048       llvm::LLVMContext &Ctx = TheModule.getContext();
3049       llvm::MDString *CoverageFile =
3050           llvm::MDString::get(Ctx, getCodeGenOpts().CoverageFile);
3051       for (int i = 0, e = CUNode->getNumOperands(); i != e; ++i) {
3052         llvm::MDNode *CU = CUNode->getOperand(i);
3053         llvm::Value *node[] = { CoverageFile, CU };
3054         llvm::MDNode *N = llvm::MDNode::get(Ctx, node);
3055         GCov->addOperand(N);
3056       }
3057     }
3058   }
3059 }
3060 
3061 llvm::Constant *CodeGenModule::EmitUuidofInitializer(StringRef Uuid,
3062                                                      QualType GuidType) {
3063   // Sema has checked that all uuid strings are of the form
3064   // "12345678-1234-1234-1234-1234567890ab".
3065   assert(Uuid.size() == 36);
3066   const char *Uuidstr = Uuid.data();
3067   for (int i = 0; i < 36; ++i) {
3068     if (i == 8 || i == 13 || i == 18 || i == 23) assert(Uuidstr[i] == '-');
3069     else                                         assert(isHexDigit(Uuidstr[i]));
3070   }
3071 
3072   llvm::APInt Field0(32, StringRef(Uuidstr     , 8), 16);
3073   llvm::APInt Field1(16, StringRef(Uuidstr +  9, 4), 16);
3074   llvm::APInt Field2(16, StringRef(Uuidstr + 14, 4), 16);
3075   static const int Field3ValueOffsets[] = { 19, 21, 24, 26, 28, 30, 32, 34 };
3076 
3077   APValue InitStruct(APValue::UninitStruct(), /*NumBases=*/0, /*NumFields=*/4);
3078   InitStruct.getStructField(0) = APValue(llvm::APSInt(Field0));
3079   InitStruct.getStructField(1) = APValue(llvm::APSInt(Field1));
3080   InitStruct.getStructField(2) = APValue(llvm::APSInt(Field2));
3081   APValue& Arr = InitStruct.getStructField(3);
3082   Arr = APValue(APValue::UninitArray(), 8, 8);
3083   for (int t = 0; t < 8; ++t)
3084     Arr.getArrayInitializedElt(t) = APValue(llvm::APSInt(
3085           llvm::APInt(8, StringRef(Uuidstr + Field3ValueOffsets[t], 2), 16)));
3086 
3087   return EmitConstantValue(InitStruct, GuidType);
3088 }
3089